JP2001267043A - Ceramic heater for semiconductor manufacture and inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic heater excellent in uniformity of temperature with a ceramic material of high thermal conductivity as a heater substrate. SOLUTION: With the disc-shaped ceramic heater 100, a heating element patterns 2 bent on the surface or inside of a ceramic substrate 1 in a certain arc are arrayed with nearly constant width.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater mainly used in the semiconductor industry, and more particularly, to a ceramic heater for drying provided with a heating element pattern in which a singular point whose temperature is lowered does not occur.

[0002]

2. Description of the Related Art Semiconductor-applied products are extremely important products required in various industries. A typical example of a semiconductor chip is a silicon wafer obtained by slicing a silicon single crystal to a predetermined thickness. Is manufactured by forming various circuits and the like on this silicon wafer.

In order to form these various circuits, a conductive thin film or the like is formed on a silicon wafer, and then an etching resist made of a photosensitive resin or the like is applied through a mask having a circuit pattern, and pattern etching is performed. I do. When applying this etching resist, since the photosensitive resin is a viscous liquid, it is necessary to dry after the application, and it is usual to place a silicon wafer coated with the photosensitive resin on a heater and heat and dry it. Is being done. In addition, it was necessary to heat the wafer during plasma etching, sputtering, and the like.

A heater of this type for mounting and drying a semiconductor wafer such as a silicon wafer on a heater by heating is conventionally provided with a heating element such as an electric resistor on the back side of an aluminum substrate. Although the thing was used a lot, since the substrate made of aluminum requires about 15 mm in thickness,
Not only is it difficult to handle because of the large weight and bulkiness, but also because it is heating by an electric resistor, the temperature controllability from the viewpoint of temperature followability to the current flow is insufficient, and uniform heating is obtained. It was not easy. Therefore, as disclosed in JP-A-11-40330,
There has been proposed a ceramic heater provided with a linear heating element formed by sintering metal particles or the like on the surface of a plate-like body made of a nitride ceramic or the like.

[0005]

However, when a heating element is formed in such a ceramic heater, if the heating element is formed in a pattern having a bent portion, the temperature of the bent portion decreases, and the surface temperature becomes uneven. However, there was still room for improvement. Such uneven surface temperature was more remarkable in ceramics having higher thermal conductivity such as nitride ceramics.

An object of the present invention is to provide a ceramic heater excellent in temperature uniformity by using a ceramic material having a high thermal conductivity as a heater substrate.

[0007]

In order to solve the above problems SUMMARY OF THE INVENTION The ceramic heater according to claim 1 is intended to heating element pattern is formed on the surface of the ceramic substrate of disk shape, wherein Ceramic is nitride ceramic
Alternatively, the heating element pattern is made of a carbide ceramic, and has a gist in which the heating element pattern has a bent portion that bends in a curved manner. The ceramic heater according to claim 2, wherein a heating element pattern is formed inside a disk-shaped ceramic substrate,
Is made of nitride ceramic or carbide ceramic.
The heating element pattern and the ceramic substrate are integrally
The gist of the present invention is such that the heating element pattern has a bent portion that bends in a curved manner. In a third aspect of the present invention, a heating element pattern is formed on a surface of a disk-shaped ceramic substrate, and the heating element pattern has a bent portion that bends in a curved manner. The gist is that the radius of curvature is 0.1 to 20 mm. Further, in the ceramic heater according to the fourth aspect, the heating element pattern is integrated inside the disc-shaped ceramic substrate.
The heating element pattern has a bent portion which bends in a round shape, and has a radius of curvature of 0.1 to 20 mm.

[0008] With this configuration, there is no temperature drop at the bent portion of the heating element arrangement pattern (sometimes called a heating element pattern). If the bent portion does not draw a radius, for example, if it bends at a right angle, the temperature of this right angle portion will drop. In the following description, the heating element pattern is represented by a shape in a top view, but the position in the thickness direction of the ceramic substrate on which the heating element is disposed may not be on the same plane.
It may include a portion that is vertically positioned in the thickness direction.

The present inventors have conducted intensive studies on the causes of the problems according to the prior art, and as a result, have found the following causes. FIG. 5 shows a heating element 32 used in a conventional ceramic heater. As shown in FIG. 5, a part of the heating element is bent at a right angle. Then, the temperature of the right-angled bent portion (arrow 32a) is lower than the temperatures of the other portions. The reason is that the pattern widths h1 and h3 of the substantially straight portion and the pattern width h2 of the right-angled bent portion are different. In the case shown in FIG.
Since the pattern width h2 is larger than the pattern widths h1 and h3, the resistance value of the portion having the pattern width h2 decreases. However, a singular point (spot) whose temperature decreases in the corresponding portion is generated. .

In particular, in the case of a disk-shaped ceramic heater, uniformity of temperature distribution is required unlike a square-shaped ceramic heater. In the case of a square ceramic heater, since the propagation of heat is concentric, the surface temperature at the four corners is reduced, and therefore uniform temperature distribution is not originally required. This is apparent from FIGS.
You. FIG. 7 shows a square ceramic heater, and FIG.
Temperature rises to 400 ° C and the surface of the heated object such as a wafer
It is the figure which observed the surface with the thermoviewer. After all, the four corners
The temperature is low in the minute, and the square ceramic heater
Characteristics that are not originally required such as uniformity of temperature distribution.
It turns out that it is sex. However, in the case of a disc shape, since the temperature distribution can be made uniform, uniformity of the temperature distribution is required, and the semiconductor wafer can be mounted because of the uniformity. For this reason, in such a disk shape, it is necessary to prevent the occurrence of a singular point (spot) whose temperature has decreased.

Therefore, the present inventors have established that the arrangement pattern of the heating element is provided with a bent portion which bends in a round shape as shown in FIG. The inventors have found that the present invention can prevent the reduction of the resistance value and the occurrence of a singular point (spot) having a lowered temperature, thereby completing the present invention.

According to the ceramic heater having the above configuration, since the bent portion of the heating element pattern is bent in a round shape, the width of the pattern becomes substantially constant, and a local decrease in temperature does not occur. Therefore, the temperature of the ceramic heater is made uniform. Incidentally, Japanese Patent Application Laid-Open No. 9-289
No. 075, Utility Model Publication No. 3-19292,
Utility Model Publication No. 54-128945 discloses a square
Roundness is formed in the bending pattern of the ceramic heater
Is disclosed, but this is a square-shaped heater.
And not a disk shape as in the present invention. For this reason
The temperature at the four corners drops, and temperature uniformity cannot be achieved at all
No. Japanese Patent Application Laid-Open No. 9-82786 discloses a heating element battery.
A heater that forms a space between
Although disclosed, this is the same as the present invention, which
The heating element is not integrated. For this reason, the space
Because the heat is not transmitted in minutes,
The degree cannot be equalized. Also, Japanese Unexamined Patent Publication No.
No. 6936 discloses a heating element on one side of a ceramic heating plate.
Discloses an electric heating device provided with the above. However, this
Is used for microwave ovens and electric stoves,
Considering the effect on
Water-resistant, non-toxic ceramics such as Mina and silica,
In other words, oxide ceramic must be used,
Nitride and carbide ceramics as in the present invention can not be used
Absent. In such an oxide ceramic, the temperature tracking property (increased
(The temperature does not rise immediately even when heated.) Also this
In these documents, the radius of curvature of the bending is not described or suggested,
These documents hinder the patentability of the present invention.
Note that there is no By the way, according to the present invention,
Lamic heater is 150 ℃ ～ 800 ℃ depending on the application
Can be used with The term “bending” in the present invention refers to FIG.
Pattern before and after the bent part of the heating element pattern
As shown in FIG. 3, the heating element pattern
Pattern forms right angle, acute angle, obtuse angle before and after bending
But putter around the bent part like the latter.
The temperature tends to drop when the button has an angle,
The arrangement according to the invention is particularly advantageous.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a plan view showing a main part of a ceramic heater 100 according to an embodiment of the present invention, and FIG. 1B is an enlarged view of a dotted line in FIG. Things. FIG. 2 is an enlarged view of a heating element pattern provided on the ceramic heater 100, and FIG. 3 is an enlarged view of a part of the heating element pattern. FIG. 4 shows the ceramic heater 10.
FIG. 2 is a partial cross-sectional view showing the structure of No. 0.

In these figures, the ceramic heater 1
Reference numeral 00 denotes a plate-shaped ceramic substrate 1 made of insulating nitride ceramics or carbide ceramics, and a heating element pattern 2 having a specific width on one main surface of the ceramic substrate 1 and having a flat cross section, for example. It is formed as shown in FIG. 1, and a silicon wafer or the like is placed on another main surface and heated.

The shape of the heating element pattern is a linear shape or a wide, substantially straight line or curve. The shape of the cross section of the heating element is not limited as long as it is flat, and may be square, elliptical, or the like. Further, the linear heating element may have a spiral shape. The aspect ratio (width of the heating element / thickness of the heating element) of the cross section of the heating element pattern 2 is desirably 10 to 5000. By adjusting to this range,
This is because the resistance value of the heating element pattern 2 can be increased, and the uniformity of the temperature of the heating surface can be ensured.

Incidentally, when the thickness of the heating element pattern 2 is constant, if the aspect ratio is smaller than the above range, the amount of heat propagation in the wafer heating direction of the ceramic substrate 1 becomes small, and the heating element pattern 2 Approximate heat distribution occurs on the heating surface. Conversely, if the aspect ratio is too large, the temperature immediately above the center of the heating element pattern 2 will be high, and eventually a heat distribution similar to the heating element pattern 2 will be generated on the heating surface. Therefore, in consideration of the temperature distribution, the aspect ratio of the cross section is preferably 10 to 5000.

When the heating element pattern 2 is formed on the surface of the ceramic substrate 1, the thickness of the heating element pattern 2 is set to 1
-30 μm is preferable, and 1-10 μm is more preferable.
When the heating element pattern 2 is formed inside the ceramic substrate 1, the thickness is preferably 1 to 50 μm. A heating element pattern 2 is provided on the surface of the ceramic substrate 1.
Is formed, the width of the heating element pattern 2 is 0.1
-20 mm is preferable, and 0.1-5 mm is more preferable. Further, a heating element pattern 2 is provided inside the ceramic substrate 1.
Is formed, the width of the heating element pattern 2 is 5
~ 20 µm is preferred.

Although the heating element pattern 2 shown in FIG. 1 is a hybrid of a spiral pattern and a bent pattern, it is desirable to dispose the bent pattern at the outer edge. This is because the bent pattern can increase the wiring density, so that the temperature can be suppressed from decreasing near the outer peripheral edge, where the temperature tends to decrease. Further, the heating element pattern 2 may be constituted by only a bending pattern as shown in FIG.

Heating element pattern 2 shown in FIGS. 1 and 2
FIG. 3 shows an example of the bent portion, which has a predetermined width as shown in FIG. Therefore, the pattern width k1, k2, and k3 of the heating element pattern 2 is k1 = k2.
= K3, and the bent portion has a radius of curvature r. Therefore, the heating element pattern 2 has a configuration in which a reduction in resistance due to a difference in pattern width and a generation of a singular point (spot) whose temperature has decreased due to this are prevented.

Here, the material of the ceramic substrate is preferably an aluminum nitride sintered body, but is not limited thereto. In addition, carbide ceramics, oxide ceramics, and nitrides other than aluminum nitride may be used. Ceramics and the like are preferred.

For example, as an example of a carbide ceramic,
Metal carbide ceramics such as silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide can be given, and examples of oxide ceramics include metal oxide ceramics such as alumina, zirconia, cordierite, and mullite. Can be. Furthermore, examples of the nitride ceramic include aluminum nitride as well as metal nitride ceramics such as silicon nitride, boron nitride, and titanium nitride.

Of these ceramic materials, nitride ceramics and carbide ceramics are generally preferable to oxide ceramics in that they exhibit high thermal conductivity. These materials may be used alone or in combination of two or more. An example
For example, oxide ceramics and carbide
Lamic may be added, and oxides may be added to the carbide ceramic.
Ceramic or carbide ceramic may be added. The higher the thermal conductivity of the ceramic, the more the temperature of the bent portion drops significantly, and the greater the effect of the present invention. The ceramic substrate of the present invention
Is desired to have a thickness of 50 mm or less, particularly 18 mm or less.
Good. Especially the thickness of the ceramic substrate exceeds 18mm
And the heat capacity of the ceramic substrate increases,
When heating and cooling are provided with control means, the heat capacity increases.
This is because the temperature followability is reduced. Also,
Non-uniform temperature problem solved by the ceramic substrate of the present invention
Is a thick ceramic substrate whose thickness exceeds 18 mm
This is because it is unlikely to occur. Especially 5mm or less is optimal
It is. The thickness is desirably 1 mm or more. The present invention
The diameter of the ceramic substrate is desirably 200 mm or more.
In particular, it is desirable that it be 12 inches (300 mm) or more.
No. This is because it will become the mainstream of next-generation silicon wafers.
The problem of non-uniform temperature solved by the present invention is that the diameter is 2
It is difficult to occur with a ceramic substrate of 00 mm or less.
is there. In the ceramic substrate of the present invention,
Substrate contains 5-5000 ppm carbon
It is desirable. By incorporating carbon,
Lamic substrate can be blackened, ceramic heat
Radiant heat can be fully utilized when used as
Because it can. Carbon is amorphous
May also be crystalline. Amorphous carbon
If used, prevents a drop in volume resistivity at high temperatures.
Can be stopped, and if a crystalline material is used,
Can the thermal conductivity decrease at high temperatures be prevented?
It is. Therefore, depending on the application, crystalline carbon
And amorphous carbon may be used in combination. Also,
The content of carbon is more preferably 50 to 2000 ppm.
No. When carbon is contained in the ceramic substrate,
The brightness is N based on the value of JIS Z 8721.
It is desirable to contain carbon so as to be 4 or less.
No. The one with this level of lightness is effective for radiant heat and concealment
Because it is excellent. Here, the lightness N is the ideal black
The lightness is set to 0, the ideal white lightness is set to 10,
The perceived brightness of the color is between black and white
Each color is divided into 10 so as to have the same rate, and N0 to N10
This is indicated by a symbol. The actual measurement of lightness is N0
The comparison is made with the color chart corresponding to .about.N10. Small in this case
The first place of several points is 0 or 5. The ceramic of the present invention
Substrate, a silicon wafer is replaced with a ceramic substrate wafer
In addition to placing it in contact with the mounting surface,
C is supported by support pins, etc., and as shown in FIG.
May be held at a certain distance from the substrate.
You. In FIG. 4, the support pin 7 is
It holds a con-wafer 9. Raise and lower the support pin 7
And received the silicon wafer 9 from the transporter
And the silicon wafer 9 was placed on the ceramic substrate.
And the silicon wafer 9 is supported on pins (not shown).
It can also be heated. Also, on the bottom of the ceramic substrate
Is a heating element 2 formed on the surface of the heating element 2
A coating layer is provided. In addition, bottomed holes are provided.
However, a thermocouple is inserted here. In this form, fever
The body is formed on the surface of the ceramic substrate.
It can blow cooling gas when adjusting or cooling.
And rapid cooling is possible. Further, since the entire region in the thickness direction of the ceramic substrate can be used as a heat diffusion plate, the ceramic substrate can be made thinner and the heat capacity can be made smaller than in the case where a heating element is provided inside, so that rapid temperature rise and fall are possible. The silicon wafer 9 is heated on the wafer heating surface side opposite to the heating element formation surface. Next, a method for manufacturing the ceramic heater 100 according to the present invention will be described. In the following description, the process conditions are merely examples, and are not limited to this embodiment. Therefore, the process conditions are set with appropriate changes depending on the size of the sample, the throughput, and the like.

First, 100 parts by weight of aluminum nitride powder (average particle size: 1.1 μm) and yttria (average particle size: 0.1 μm) were used.
4 μm) 4 parts by weight, 12 parts by weight of an acrylic resin binder, and alcohol were mixed and kneaded, and then granulated by a spray dryer method. In addition, silicon carbide
When used, silicon carbide powder (average particle size: 1.0 μm) 1
00 parts by weight, C or B4 0.5 parts by weight, acrylic
Mix 12 parts by weight of resin binder and alcohol
After kneading, it is mixed with granular powder by spray dryer method.
did. It should be noted that alumina was used in test examples and the like described later.
However, in this case, alumina powder (average particle size: 1.0 μm)
, An acrylic resin binder 12 parts by weight, and an alcohol
After mixing and kneading
Granular powder was obtained.

Next, the granular powder was charged into a molding die and molded into a flat plate to obtain a formed product. A through hole for inserting a semiconductor wafer support pin into the formed form;
A recess for embedding a thermocouple was formed by drilling.

The formed body in which the through holes and the recesses were formed was hot-pressed at about 1800 ° C. and a pressure of 200 kg / ccm ² to obtain a 3 mm-thick aluminum nitride or silicon carbide plate-like sintered body. This was cut out into a disk shape having a diameter of 210 mm to obtain a ceramic substrate 1 for the ceramic heater 100. An insulating film such as an oxide film on the surface of this ceramic substrate
It is desirable to print a heating element described later after forming
No. Specifically, a glass paste is applied and 1000 ° C.
Heating and melting method and surface of ceramic substrate
Baking at 500 to 1000 ° C. in an oxidizing atmosphere.
You. Particularly in the case of carbide ceramics, if the purity is low,
Due to the gaseous conductivity, it is desirable to form an insulating film. Insulation
The thickness of the film is preferably 0.1 to 1000 μm.

A conductive paste was printed on the ceramic substrate 1 by a screen printing method so that the heating element patterns 2 were arranged in the pattern shown in FIG. The conductive paste used here was Solvest PS6 manufactured by Tokuriki Chemical Laboratory.
03D (trade name), and the conductive paste is a metal oxide composed of a mixture of lead oxide, zinc oxide, silica, boron oxide, and alumina (the weight ratio is 5/5 in this order).
5/10/25/10) 7.5% by weight based on the amount of silver
It is a so-called lead-containing silver paste. Incidentally, the average particle size of silver was 4.5 μm, and the shape was mainly flake-like.

The ceramic substrate on which the conductive paste was printed was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste, and baked on the ceramic substrate. At this time, the heating element pattern made of the lead-containing silver sintered body had a thickness of about 5 μm, a width of 2.4 mm, and a sheet resistance of 7.7 mΩ / □. The heating element pattern has a pattern that bends while drawing a radius at an edge portion near the outer periphery. The radius of curvature of the radius is desirably 0.1 mm to 20 mm. If it is too small, it becomes a right angle, and if it is too large, the heating element pattern density cannot be increased. The radius of curvature is defined by the center line (L in FIG. 3) of the heating element pattern.

Next, the concentration per liter was 80 g / l of nickel sulfate and 24 g of sodium hypophosphite.
g / l, sodium acetate 12 g / l, boric acid 8 g / l,
The ceramic substrate is immersed in an electroless nickel plating bath containing an aqueous solution having a concentration of 6 g / l ammonium chloride to deposit a nickel metal layer having a thickness of about 1 μm on the surface of the lead-containing silver sintered body. Thus, a heating element pattern was formed.

As shown in FIG. 1 (a), the heating element patterns 2, 31, 31a are formed on the ceramic substrate 1 in a predetermined pattern as shown in FIG. Metal particles and metal oxide particles can be sintered to such an extent that they are fused together. And
The form of the heating element pattern is, as shown in FIG.
What is necessary is just a width substantially straight line or curve. Therefore, it does not need to be a geometrically strict straight line or curve.

Finally, as shown in FIG. 4, silver-containing lead solder paste (Tanaka Kikinzoku Kogyo Co., Ltd.) is applied by screen printing to a portion where terminal pins 3 for securing the connection between the heating element pattern 2 and the power supply are mounted. )) Printed on the solder layer 6
Further, terminal pins 3 made of Kovar were placed on the solder layer and heated and reflowed at 420 ° C. to attach the terminal pins 3 to the surface of the heating element pattern 2.

Further, a thermocouple (not shown) for controlling the temperature was embedded in the ceramic substrate 1 to obtain a ceramic heater 100 according to the present invention. 4, reference numeral 7 denotes a support pin for supporting the semiconductor wafer 9;
Is inserted through the through-hole 8 formed in the ceramic substrate 1. Since the heating element pattern 2 has a predetermined resistance value, the heating element pattern 2 is energized from a position where a terminal pin 3 for energizing the heating element pattern 2 is attached. Generates heat by Joule heat and heats the semiconductor wafer 9.

Next, a method of manufacturing a ceramic heater (FIG. 9) having a heating element formed therein will be described.

(1) First, nitride ceramic or carbonized
Ceramic powder of binder ceramic and binder
To obtain a green sheet. The ceramic mentioned above
As the powder, for example, aluminum nitride is used.
Sintering of yttria etc.
An agent may be added. Sintering aid is 0.1 to 10 weight
Can be adjusted in%. The average particle size of the ceramic powder is
0.1 to 10 μm. In addition, a binder
Kuryl binder, ethyl cellulose, butyl cellosol
And at least one selected from polyvinyl alcohol
Is desirable. Further, as the solvent, α-terpineo
At least one selected from the group consisting of
No. The paste obtained by mixing them is
Green sheet by molding
You. Note that alumina powder can be produced under the same conditions.
Supporting silicon wafers on green sheets as needed
Providing through holes for inserting pins and recesses for embedding thermocouples
I can put it. Through holes and recesses are formed by panning
Can be achieved. The thickness of the green sheet is 0.1
About 5 mm is preferable. Next, resistance to the green sheet
Print conductor paste to be the heating element. Printing is gree
The desired aspect ratio is obtained in consideration of the contraction rate of the sheet.
Do so as to Contained in these conductive pastes
Tungsten or metal is used as the conductive ceramic particles.
Optimum is carbide of molybdenum. Hard to oxidize, heat conduction
This is because the rate is not easily reduced. Also, as metal particles
Is, for example, tungsten, molybdenum, platinum, nickel
Can be used. Conductive ceramic particles
The average particle diameter of the particles and metal particles is preferably 0.1 to 5 μm.
No. These particles are too large or too small for conductors
This is because it is difficult to print the paste. Such a pace
The metal particles or conductive ceramic particles 85
~ 97 parts by weight, acrylic, ethyl cellulose, butyl
Small amounts selected from cellosolve and polyvinyl alcohol
1.5 to 10 parts by weight of at least one binder, α-ter
Pinole, glycol, ethyl alcohol and pig
At least one solvent selected from the group consisting of
A paste for conductor prepared by mixing 0 parts by weight is optimal.
You. In addition, a hole for the conductor
The strike is filled to obtain a through-hole print. Then print
Green sheet with body and grease without printed body
And sheet. Printed material on the resistance heating element formation side
Laminating green sheets that do not
The end face is exposed and oxidized during firing for forming the resistance heating element.
This is to prevent that. If the through hole
Since the baking for forming the resistance heating element is performed with the end face exposed,
If it is difficult to oxidize metals such as nickel,
And more preferably Au-Ni.
It may be covered with gold brazing.

(2) Next, heating and pressing of the laminate are performed.
Sintering green sheet and conductor paste
Let it. Heating temperature is 1000-2000 ° C, pressurization is 1
The heating is preferably between 200 and 200 kg / cm2.
Pressurization is performed under an inert gas atmosphere. Inert gas
As can be used argon, nitrogen, etc.
You.

(3) Next, a blind hole for connecting an external terminal is formed.
Provide. At least a part of the inner wall of the blind hole is conductive
The inner wall that has been made conductive is connected to the resistance heating element 5 and the like.
It is desirable that this be done (FIG. 9B).

(4) Finally, the outside of the blind hole is put through a brazing filler metal.
Provide terminals. Furthermore, if necessary, a bottomed hole is provided,
A thermocouple can be embedded therein. Solder is silver-
Use alloys such as lead, lead-tin and bismuth-tin.
Can be. Note that the thickness of the solder layer is 0.1 to 50 μm.
Is desirable. It is enough range to secure connection by solder
Because. In this way, the ceramic shown in FIG.
Cook heater 200 can be manufactured. This ceramic heater
Reference numeral 200 denotes the resistance heating element 20 inside the ceramic substrate 10.
Since it is formed integrally with the ceramic substrate 10,
The periphery of the heat body 20 is completely in contact with the ceramic substrate 10
I have. Therefore, heat is transmitted uniformly. This ceramic
The wafer 9 is directly placed on the heating surface 10a side of the substrate 10 or
Is a certain distance (5 to 50) via the separation support pin SP.
00 [mu] m) spaced apart and heated. Heating element 20
Is exposed from the ceramic substrate by the opening. Heating element
20 is connected to a through hole S. Also,
The hole S is connected to the inner wall 40 of the hole made conductive,
In addition, the inner wall 40 is connected to the pin 30 through a gold soldering 50.
You. Support pins (lifter pins) 80 on the ceramic substrate
Is formed.

(Evaluation Test) As a product of the present invention, aluminum nitride
Heating element pattern on the surface with titanium and silicon carbide ceramic
Change the curvature of each bending pattern
Were manufactured in four types, and these were respectively manufactured in Examples 1 to 4.
And 8. Aluminum nitride ceramic, silicon carbide
Heating element pattern formed inside elementary ceramic
Manufacture four types of bending patterns with different curvatures
These were designated as Examples 9 to 16, respectively. Also compare
As shown in FIG.
Ceramic heater with heat pattern on the surface and inside
Made of aluminum nitride and silicon carbide, respectively, and compared
Examples 1 to 4 were used. Another comparative product is aluminum nitride.
Radius of curvature of 25mm with a ceramic heater of aluminum and silicon carbide
Test with a pattern with a radius on the surface and inside
Examples 1 to 4 were used. In addition, the heating element pattern
A ceramic heat sink using an alumina substrate formed inside
, And Test Examples 5 to 16 were prepared. In addition, square
Ceramic heater with aluminum nitride ceramic
Manufactured from silicon carbide ceramic (both are patterned on the surface
Formation) Comparative Examples 5 and 6, and heated to 300 ° C.
The temperature difference between the temperature and the center was measured. During the evaluation test,
For each of the example and the comparative example, a voltage of 30 was applied.
Heat to 0 ° C, JIS-C-1602 (1980) K
The temperature in the vicinity of the bent portion of the bent pattern and the temperature in the vicinity of the spiral pattern were measured with a thermocouple, and the difference was examined. Also
The temperature rise time up to 300 ° C. was measured. Table 1 shows the results.
Show. Also, the temperature of the ceramic heater was raised to 200 ° C,
This was dropped into water and it was examined whether or not cracks developed in the bent portion.

[0038]

[Table 1]

As is apparent from the results, according to the ceramic heater according to the present invention, the difference between the temperature near the bent pattern in which the radius is drawn and the temperature near the spiral pattern is 5 ° C.
However, according to the ceramic heater used as the comparative example, the difference between the temperature near the right-angled bent pattern and the temperature near the spiral pattern was 10 ° C to 15 ° C.
Therefore, according to the ceramic heater according to the present invention, it has been found that the temperature of the ceramic substrate can be made uniform.
According to this result, in the case of the ceramic heater having the above configuration, the radius of curvature is optimally about 1 to 15 mm. In addition, cracks did not occur in the thermal shock test in the examples, whereas cracks were observed in the comparative examples.
In addition, the following is considered. The radius of curvature is 20m
If m is exceeded, the temperature difference will increase. This is a puta
The reason for this is that the energy density is reduced. Therefore, the radius of curvature
Indicates that the effect of the present invention is remarkable in the range of 0.1 to 20 mm.
You. This effect is also more pronounced in aluminum nitride than in alumina.
And silicon carbide. This is because aluminum nitride and carbonized
Silicon has better temperature followability (that is, the temperature rise time
This is because they are sensitive to variations in calorific value.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

The ceramic heater according to the present invention has the following features.
If the electrodes are embedded in the ceramic substrate, it can be used as an electrostatic chuck. Further, the ceramic heater according to the present invention, a conductor layer on the surface of the ceramic substrate,
If an electrode is buried inside, it can be used as a wafer prober.

[0042]

The ceramic heater according to the present invention has a bent portion which bends by drawing a radius on the surface or inside of a disk-shaped ceramic substrate mainly made of a nitride ceramic or a carbide ceramic. No temperature-lowering portion is generated in the portion, and the temperature uniformity is excellent. It is particularly suitable for a disk-shaped ceramic heater.

[Brief description of the drawings]

FIG. 1A is a plan view showing a main part of a ceramic heater according to an embodiment of the present invention, and FIG.
It is the elements on larger scale of the dotted line surrounding of (a).

FIG. 2 is a plan view showing an example of a heating element pattern of the ceramic heater according to one embodiment of the present invention.

FIG. 3 is an enlarged partial view showing a part of a heating element pattern of the ceramic heater according to one embodiment of the present invention.

FIG. 4 is a partial sectional view showing a structure of a ceramic heater according to one embodiment of the present invention.

FIG. 5 is a partially enlarged view showing a part of a heating element pattern of a conventional ceramic heater in an enlarged manner.

FIG. 6 is a plan view showing a main part of a ceramic heater used as a comparative example.

FIG. 7 is a drawing substitute photograph of a square ceramic heater.
is there.

FIG. 8 is a drawing substitute photograph of a thermoviewer.

9 (a) and 9 (b) have a heating element integrally formed therein.
FIG. 3 is a diagram showing a configuration in a case where the circumstance has occurred.

[Explanation of symbols]

 Reference Signs List 100 ceramic heater 1 ceramic substrate 2, 31, 31a heating element pattern

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[Procedure amendment]

[Submission date] August 10, 2000 (2008.1.
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Ceramic heater

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater mainly used in the semiconductor industry, and more particularly, to a ceramic heater for drying provided with a heating element pattern in which a singular point whose temperature is lowered does not occur.

[0002]

2. Description of the Related Art Semiconductor-applied products are extremely important products required in various industries. A typical example of a semiconductor chip is a silicon wafer obtained by slicing a silicon single crystal to a predetermined thickness. Is manufactured by forming various circuits and the like on this silicon wafer.

In order to form these various circuits, a conductive thin film or the like is formed on a silicon wafer, and then an etching resist made of a photosensitive resin or the like is applied through a mask having a circuit pattern, and pattern etching is performed. I do. When applying this etching resist, since the photosensitive resin is a viscous liquid, it is necessary to dry after the application, and it is usual to place a silicon wafer coated with the photosensitive resin on a heater and heat and dry it. Is being done. In addition, it was necessary to heat the wafer during plasma etching, sputtering, and the like.

A heater of this type for mounting and drying a semiconductor wafer such as a silicon wafer on a heater by heating is conventionally provided with a heating element such as an electric resistor on the back side of an aluminum substrate. Although the thing was used a lot, since the substrate made of aluminum requires about 15 mm in thickness,
Not only is it difficult to handle because of the large weight and bulkiness, but also because it is heating by an electric resistor, the temperature controllability from the viewpoint of temperature followability to the current flow is insufficient, and uniform heating is obtained. It was not easy. Therefore, as disclosed in JP-A-11-40330,
There has been proposed a ceramic heater provided with a linear heating element formed by sintering metal particles or the like on the surface of a plate-like body made of a nitride ceramic or the like.

[0005]

However, when a heating element is formed in such a ceramic heater, if the heating element is formed in a pattern having a bent portion, the temperature of the bent portion decreases, and the surface temperature becomes uneven. However, there was still room for improvement. Such uneven surface temperature was more remarkable in ceramics having higher thermal conductivity such as nitride ceramics.

An object of the present invention is to provide a ceramic heater excellent in temperature uniformity by using a ceramic material having a high thermal conductivity as a heater substrate.

[0007]

According to a first aspect of the present invention, there is provided a ceramic heater comprising a disk-shaped ceramic substrate having a heating element pattern formed on a surface thereof. The ceramic is made of a nitride ceramic or a carbide ceramic, and the heating element pattern has a bent portion which bends in a round shape. The ceramic heater according to claim 2, wherein a heating element pattern is formed inside a disk-shaped ceramic substrate, wherein the ceramic is made of a nitride ceramic or a carbide ceramic. The gist is that the pattern and the ceramic substrate are integrally formed, and the heating element pattern has a bent portion which is bent in a curved manner. In a third aspect of the present invention, a heating element pattern is formed on a surface of a disk-shaped ceramic substrate, and the heating element pattern has a bent portion that bends in a curved manner. The gist is that the radius of curvature is 0.1 to 20 mm. The ceramic heater according to claim 4, wherein a heating element pattern is integrally formed inside a disk-shaped ceramic substrate, and the heating element pattern is bent in a curved manner. Having a radius of curvature of 0.1 to 20 mm.

[0008] With this configuration, there is no temperature drop at the bent portion of the heating element arrangement pattern (sometimes called a heating element pattern). If the bent portion does not draw a radius, for example, if it bends at a right angle, the temperature of this right angle portion will drop. In the following description, the heating element pattern is represented by a shape in a top view, but the position in the thickness direction of the ceramic substrate on which the heating element is disposed may not be on the same plane.
It may include a portion that is vertically positioned in the thickness direction.

The present inventors have conducted intensive studies on the causes of the problems according to the prior art, and as a result, have found the following causes. FIG. 5 shows a heating element 32 used in a conventional ceramic heater. As shown in FIG. 5, a part of the heating element is bent at a right angle. Then, the temperature of the right-angled bent portion (arrow 32a) is lower than the temperatures of the other portions. The reason is that the pattern widths h1 and h3 of the substantially straight portion and the pattern width h2 of the right-angled bent portion are different. In the case shown in FIG.
Since the pattern width h2 is larger than the pattern widths h1 and h3, the resistance value of the portion having the pattern width h2 decreases. However, a singular point (spot) whose temperature decreases in the corresponding portion is generated. .

In particular, in the case of a disk-shaped ceramic heater, uniformity of temperature distribution is required unlike a square-shaped ceramic heater. In the case of a square ceramic heater, since the propagation of heat is concentric, the surface temperature at the four corners is reduced, and therefore uniform temperature distribution is not originally required. This is apparent from FIGS. FIG. 7 shows a square ceramic heater.
FIG. 4 is a diagram in which the temperature is raised to 400 ° C. and the surface of a heated surface of an object to be heated such as a wafer is observed with a thermoviewer. As a result, the temperature of the four corners is low, and it can be seen that the rectangular ceramic heater has characteristics not originally required, such as uniformity of temperature distribution. However, in the case of a disc shape, since the temperature distribution can be made uniform, uniformity of the temperature distribution is required, and the semiconductor wafer can be mounted because of the uniformity. For this reason, in such a disk shape, it is necessary to prevent the occurrence of a singular point (spot) whose temperature has decreased.

Therefore, the present inventors have established that the arrangement pattern of the heating element is provided with a bent portion which bends in a round shape as shown in FIG. The inventors have found that the present invention can prevent the reduction of the resistance value and the occurrence of a singular point (spot) having a lowered temperature, thereby completing the present invention.

According to the ceramic heater having the above configuration, since the bent portion of the heating element pattern is bent in a round shape, the width of the pattern becomes substantially constant, and a local decrease in temperature does not occur. Therefore, the temperature of the ceramic heater is made uniform. Incidentally, Japanese Patent Application Laid-Open No. 9-289
No. 075, Utility Model Publication No. 3-19292,
Japanese Utility Model Publication No. 54-128945 discloses a square ceramic heater in which a bent portion is formed in a curved pattern portion. This is a square heater, which is a circular heater as in the present invention. It is not a plate shape. As a result, the temperatures at the four corners decrease, and temperature uniformity cannot be achieved at all. Japanese Patent Application Laid-Open No. Hei 9-82786 discloses a heater in which a space is formed between a bulk of a heating element and a ceramic substrate. This is a device in which a ceramic substrate and a heating element are integrated as in the present invention. is not. For this reason, since heat is not transmitted in the space, the temperature of the heating surface cannot be made uniform as in the present invention. Also, Japanese Unexamined Patent Publication No.
Japanese Patent No. 6936 discloses an electric heating appliance in which a heating element is arranged on one side of a ceramic heating plate. However, this is used for microwave ovens and electric stoves, and considering the effects on the human body and the reactivity of ceramics, there are water-resistant and non-toxic ceramics such as alumina and silica,
In other words, oxide ceramic must be used,
A nitride or carbide ceramic as in the present invention cannot be used. Such an oxide ceramic has poor temperature followability (the temperature does not immediately rise even when the temperature rises). In these documents, the radius of curvature of the bending is not described or suggested,
It should be noted that these documents do not prevent the patentability of the present invention. Incidentally, the ceramic heater according to the present invention has a temperature of 150 ° C. to 800 ° C. depending on the application.
Can be used with The term “bending” in the present invention refers to FIG.
As shown in FIG. 3, the pattern is substantially parallel before and after the bent portion of the heating element pattern, or as shown in FIG. 3, the pattern forms a right angle, an acute angle, and an obtuse angle before and after the bent portion of the heating element pattern. However, when the pattern has an angle before and after the bent part like the latter, the temperature tends to drop,
The arrangement according to the invention is particularly advantageous.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a plan view showing a main part of a ceramic heater 100 according to an embodiment of the present invention, and FIG. 1B is an enlarged view of a dotted line in FIG. Things. FIG. 2 is an enlarged view of a heating element pattern provided on the ceramic heater 100, and FIG. 3 is an enlarged view of a part of the heating element pattern. FIG. 4 shows the ceramic heater 10.
FIG. 2 is a partial cross-sectional view showing the structure of No. 0.

In these figures, the ceramic heater 1
Reference numeral 00 denotes a plate-shaped ceramic substrate 1 made of insulating nitride ceramics or carbide ceramics, and a heating element pattern 2 having a specific width on one main surface of the ceramic substrate 1 and having a flat cross section, for example. It is formed as shown in FIG. 1, and a silicon wafer or the like is placed on another main surface and heated.

The shape of the heating element pattern is a linear shape or a wide, substantially straight line or curve. The shape of the cross section of the heating element is not limited as long as it is flat, and may be square, elliptical, or the like. Further, the linear heating element may have a spiral shape. The aspect ratio (width of the heating element / thickness of the heating element) of the cross section of the heating element pattern 2 is desirably 10 to 5000. By adjusting to this range,
This is because the resistance value of the heating element pattern 2 can be increased, and the uniformity of the temperature of the heating surface can be ensured.

Incidentally, when the thickness of the heating element pattern 2 is constant, if the aspect ratio is smaller than the above range, the amount of heat propagation in the wafer heating direction of the ceramic substrate 1 becomes small, and the heating element pattern 2 Approximate heat distribution occurs on the heating surface. Conversely, if the aspect ratio is too large, the temperature immediately above the center of the heating element pattern 2 will be high, and eventually a heat distribution similar to the heating element pattern 2 will be generated on the heating surface. Therefore, in consideration of the temperature distribution, the aspect ratio of the cross section is preferably 10 to 5000.

When the heating element pattern 2 is formed on the surface of the ceramic substrate 1, the thickness of the heating element pattern 2 is set to 1
-30 μm is preferable, and 1-10 μm is more preferable.
When the heating element pattern 2 is formed inside the ceramic substrate 1, the thickness is preferably 1 to 50 μm. A heating element pattern 2 is provided on the surface of the ceramic substrate 1.
Is formed, the width of the heating element pattern 2 is 0.1
-20 mm is preferable, and 0.1-5 mm is more preferable. Further, a heating element pattern 2 is provided inside the ceramic substrate 1.
Is formed, the width of the heating element pattern 2 is 5
~ 20 µm is preferred.

Although the heating element pattern 2 shown in FIG. 1 is a hybrid of a spiral pattern and a bent pattern, it is desirable to dispose the bent pattern at the outer edge. This is because the bent pattern can increase the wiring density, so that the temperature can be suppressed from decreasing near the outer peripheral edge, where the temperature tends to decrease. Further, the heating element pattern 2 may be constituted by only a bending pattern as shown in FIG.

Heating element pattern 2 shown in FIGS. 1 and 2
FIG. 3 shows an example of the bent portion, which has a predetermined width as shown in FIG. Therefore, the pattern width k1, k2, and k3 of the heating element pattern 2 is k1 = k2.
= K3, and the bent portion has a radius of curvature r. Therefore, the heating element pattern 2 has a configuration in which a reduction in resistance due to a difference in pattern width and a generation of a singular point (spot) whose temperature has decreased due to this are prevented.

Here, the material of the ceramic substrate is preferably an aluminum nitride sintered body, but is not limited thereto. In addition, carbide ceramics, oxide ceramics, and nitrides other than aluminum nitride may be used. Ceramics and the like are preferred.

For example, as an example of a carbide ceramic,
Metal carbide ceramics such as silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide can be given, and examples of oxide ceramics include metal oxide ceramics such as alumina, zirconia, cordierite, and mullite. Can be. Furthermore, examples of the nitride ceramic include aluminum nitride as well as metal nitride ceramics such as silicon nitride, boron nitride, and titanium nitride.

Of these ceramic materials, nitride ceramics and carbide ceramics are generally preferable to oxide ceramics in that they exhibit high thermal conductivity. These materials may be used alone or in combination of two or more. For example, an oxide ceramic or a carbide ceramic may be added to the nitride ceramic, or an oxide ceramic or a carbide ceramic may be added to the carbide ceramic. The higher the thermal conductivity of the ceramic, the more the temperature of the bent portion drops significantly, and the greater the effect of the present invention. The thickness of the ceramic substrate of the present invention is desirably 50 mm or less, particularly preferably 18 mm or less. In particular, when the thickness of the ceramic substrate exceeds 18 mm, the heat capacity of the ceramic substrate increases, and particularly when heating and cooling with the provision of a temperature control means, the temperature followability is reduced due to the large heat capacity. is there. Also,
The problem of non-uniform temperature solved by the ceramic substrate of the present invention is because it does not easily occur with a ceramic substrate having a thickness exceeding 18 mm. Particularly, 5 mm or less is optimal. The thickness is desirably 1 mm or more. The diameter of the ceramic substrate of the present invention is desirably 200 mm or more.
In particular, it is desirable to be 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation silicon wafers.
Further, the problem of non-uniform temperature solved by the present invention is that the diameter is 2 mm.
This is because it hardly occurs on a ceramic substrate of 00 mm or less. In the ceramic substrate of the present invention, the ceramic substrate desirably contains 5 to 5000 ppm of carbon. By containing carbon, the ceramic substrate can be blackened, and radiant heat can be sufficiently utilized when used as a ceramic heater. The carbon may be amorphous or crystalline. When amorphous carbon is used, a decrease in volume resistivity at high temperatures can be prevented, and when crystalline one is used,
This is because a decrease in thermal conductivity at a high temperature can be prevented. Therefore, depending on the application, both crystalline carbon and amorphous carbon may be used in combination. Further, the content of carbon is more preferably 50 to 2000 ppm. When carbon is contained in the ceramic substrate,
The brightness is N based on the value of JIS Z 8721.
It is desirable that carbon be contained so as to be 4 or less. This is because a material having such a lightness is excellent in radiant heat and concealing property. Here, the lightness N is 0 for an ideal black lightness, 10 for an ideal white lightness, and a perception of the brightness of the color between these black lightness and white lightness. Each color is divided into 10 so as to have a uniform rate, and is displayed with symbols N0 to N10. The actual measurement of lightness is N0
The comparison is made with the color chart corresponding to .about.N10. In this case, the first decimal place is 0 or 5. In the ceramic substrate of the present invention, in addition to placing the silicon wafer in contact with the wafer mounting surface of the ceramic substrate, the silicon wafer is supported by support pins or the like, and the silicon wafer is connected to the ceramic substrate as shown in FIG. In some cases, a certain interval is maintained. In FIG. 4, the support pins 7 are inserted through the through holes 8 to hold the silicon wafer 9. By moving the support pins 7 up and down, it is possible to receive the silicon wafer 9 from the transfer machine, place the silicon wafer 9 on a ceramic substrate, and heat the silicon wafer 9 while supporting the silicon wafer 9 on pins (not shown). A heating element 2 is formed on the bottom surface of the ceramic substrate, and a metal coating layer is provided on the surface of the heating element 2. A bottomed hole is provided, into which a thermocouple is inserted. In this embodiment, the heating element is formed on the surface of the ceramic substrate, and can adjust the resistance value or blow a cooling gas at the time of cooling, thereby enabling rapid cooling. Further, since the entire region in the thickness direction of the ceramic substrate can be used as a heat diffusion plate, the ceramic substrate can be made thinner and the heat capacity can be made smaller than in the case where a heating element is provided inside, so that rapid temperature rise and fall are possible. The silicon wafer 9 is heated on the wafer heating surface side opposite to the heating element formation surface. Next, a method for manufacturing the ceramic heater 100 according to the present invention will be described. In the following description, the process conditions are merely examples, and are not limited to this embodiment. Therefore, the process conditions are set with appropriate changes depending on the size of the sample, the throughput, and the like.

First, 100 parts by weight of aluminum nitride powder (average particle size: 1.1 μm) and yttria (average particle size: 0.1 μm) were used.
4 μm) 4 parts by weight, 12 parts by weight of an acrylic resin binder, and alcohol were mixed and kneaded, and then granulated by a spray dryer method. Also, when using silicon carbide, silicon carbide powder (average particle size: 1.0 μm)
After mixing and kneading 00 parts by weight, 0.5 parts by weight of C or B4C, 12 parts by weight of an acrylic resin binder, and alcohol, a granular powder was obtained by a spray dryer method. In addition, although alumina is used in a test example and the like described below, in this case, alumina powder (average particle size: 1.0 μm)
And 12 parts by weight of an acrylic resin binder and alcohol were mixed and kneaded, and then a granular powder was formed by a spray dryer method.

Next, the granular powder was charged into a molding die and molded into a flat plate to obtain a formed product. A through hole for inserting a semiconductor wafer support pin into the formed form;
A recess for embedding a thermocouple was formed by drilling.

The formed body in which the through holes and the recesses were formed was hot-pressed at about 1800 ° C. and a pressure of 200 kg / ccm ² to obtain a 3 mm-thick aluminum nitride or silicon carbide plate-like sintered body. This was cut out into a disk shape having a diameter of 210 mm to obtain a ceramic substrate 1 for the ceramic heater 100. After forming an insulating film such as an oxide film on the surface of the ceramic substrate, it is desirable to print a heating element described later. Specifically, a glass paste is applied and 1000 ° C.
There is a method of melting by heating and a method of baking the surface of the ceramic substrate at 500 to 1000 ° C. in an oxidizing atmosphere as described above. In particular, in the case of carbide ceramics, if the purity is low, there is electrical conductivity, so it is desirable to form an insulating film. The thickness of the insulating film is preferably 0.1 to 1000 μm.

A conductive paste was printed on the ceramic substrate 1 by a screen printing method so that the heating element patterns 2 were arranged in the pattern shown in FIG. The conductive paste used here was Solvest PS6 manufactured by Tokuriki Chemical Laboratory.
03D (trade name), and the conductive paste is a metal oxide composed of a mixture of lead oxide, zinc oxide, silica, boron oxide, and alumina (the weight ratio is 5/5 in this order).
5/10/25/10) 7.5% by weight based on the amount of silver
It is a so-called lead-containing silver paste. Incidentally, the average particle size of silver was 4.5 μm, and the shape was mainly flake-like.

The ceramic substrate on which the conductive paste was printed was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste, and baked on the ceramic substrate. At this time, the heating element pattern made of the lead-containing silver sintered body had a thickness of about 5 μm, a width of 2.4 mm, and a sheet resistance of 7.7 mΩ / □. The heating element pattern has a pattern that bends while drawing a radius at an edge portion near the outer periphery. The radius of curvature of the radius is desirably 0.1 mm to 20 mm. If it is too small, it becomes a right angle, and if it is too large, the heating element pattern density cannot be increased. The radius of curvature is defined by the center line (L in FIG. 3) of the heating element pattern.

Next, the concentration per liter was 80 g / l of nickel sulfate and 24 g of sodium hypophosphite.
g / l, sodium acetate 12 g / l, boric acid 8 g / l,
The ceramic substrate is immersed in an electroless nickel plating bath containing an aqueous solution having a concentration of 6 g / l ammonium chloride to deposit a nickel metal layer having a thickness of about 1 μm on the surface of the lead-containing silver sintered body. Thus, a heating element pattern was formed.

As shown in FIG. 1 (a), the heating element patterns 2, 31, 31a are formed on the ceramic substrate 1 in a predetermined pattern as shown in FIG. Metal particles and metal oxide particles can be sintered to such an extent that they are fused together. And
The form of the heating element pattern is, as shown in FIG.
What is necessary is just a width substantially straight line or curve. Therefore, it does not need to be a geometrically strict straight line or curve.

Finally, as shown in FIG. 4, silver-containing lead solder paste (Tanaka Kikinzoku Kogyo Co., Ltd.) is applied by screen printing to a portion where terminal pins 3 for securing the connection between the heating element pattern 2 and the power supply are mounted. )) Printed on the solder layer 6
Further, terminal pins 3 made of Kovar were placed on the solder layer and heated and reflowed at 420 ° C. to attach the terminal pins 3 to the surface of the heating element pattern 2.

Further, a thermocouple (not shown) for controlling the temperature was embedded in the ceramic substrate 1 to obtain a ceramic heater 100 according to the present invention. 4, reference numeral 7 denotes a support pin for supporting the semiconductor wafer 9;
Is inserted through the through-hole 8 formed in the ceramic substrate 1. Since the heating element pattern 2 has a predetermined resistance value, the heating element pattern 2 is energized from a position where a terminal pin 3 for energizing the heating element pattern 2 is attached. Generates heat by Joule heat and heats the semiconductor wafer 9.

Next, a method of manufacturing a ceramic heater (FIG. 9) having a heating element formed therein will be described.

(1) First, a ceramic powder of a nitride ceramic or a carbide ceramic is mixed with a binder and a solvent to obtain a green sheet. As the above-mentioned ceramic powder, for example, aluminum nitride or the like can be used, and a sintering aid such as yttria may be added as necessary. The sintering aid can be adjusted at 0.1 to 10% by weight. The average particle size of the ceramic powder is
0.1 to 10 μm. The binder is preferably at least one selected from an acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol. Further, as the solvent, at least one selected from α-terpineol and glycol is desirable. A paste obtained by mixing these is shaped into a sheet by a doctor blade method to produce a green sheet. Note that alumina powder can be produced under the same conditions.
The green sheet may be provided with a through hole for inserting a support pin of the silicon wafer and a concave portion for burying a thermocouple as needed. The through holes and the concave portions can be formed by panning or the like. The thickness of the green sheet is 0.1
About 5 mm is preferable. Next, a conductor paste to be a resistance heating element is printed on the green sheet. Printing is performed so as to obtain a desired aspect ratio in consideration of the shrinkage ratio of the green sheet. As the conductive ceramic particles contained in these conductive pastes, carbides of tungsten or molybdenum are most suitable. This is because it is hard to be oxidized and the thermal conductivity is hard to decrease. Further, as the metal particles, for example, tungsten, molybdenum, platinum, nickel and the like can be used. The average particle diameter of the conductive ceramic particles and the metal particles is preferably 0.1 to 5 μm. This is because it is difficult to print the conductor paste when these particles are too large or too small. As such a paste, metal particles or conductive ceramic particles 85 may be used.
To 97 parts by weight, 1.5 to 10 parts by weight of at least one kind of binder selected from acrylic, ethyl cellulose, butyl cellosolve and polyvinyl alcohol, and at least one kind of solvent selected from α-terpineol, glycol, ethyl alcohol and butanol. 0.5-1
The paste for conductor prepared by mixing 0 parts by weight is most suitable. Further, a conductor paste is filled into the holes formed by punching or the like to obtain a through-hole print. Next, a green sheet having a printed body and a green sheet having no printed body are laminated. The reason why the green sheet having no printed body is laminated on the side where the resistance heating element is formed is to prevent the end face of the through hole from being exposed and being oxidized during firing for forming the resistance heating element. If baking for forming the resistance heating element is performed while the end face of the through hole is exposed, it is necessary to sputter a metal that is difficult to oxidize, such as nickel, and more preferably to coat it with Au-Ni gold solder. Is also good.

(2) Next, the laminate is heated and pressurized to integrally sinter the green sheet and the conductive paste. Heating temperature is 1000-2000 ° C, pressurization is 1
The heating and pressurizing are preferably performed in an inert gas atmosphere. As the inert gas, argon, nitrogen, or the like can be used.

(3) Next, a blind hole for connecting an external terminal is provided. At least a part of the inner wall of the blind hole is preferably made conductive, and the conductive inner wall is preferably connected to the resistance heating element 5 or the like (FIG. 9B).

(4) Finally, an external terminal is provided in the blind hole via a brazing filler metal. Furthermore, if necessary, a bottomed hole is provided,
A thermocouple can be embedded therein. Solder is silver-
Alloys such as lead, lead-tin and bismuth-tin can be used. Note that the thickness of the solder layer is 0.1 to 50 μm.
Is desirable. This is because the range is sufficient to secure the connection by soldering. With such a method, the ceramic heater 200 shown in FIG. 9A can be manufactured. In the ceramic heater 200, the resistance heating element 20 is formed integrally with the ceramic substrate 10 inside the ceramic substrate 10, and the periphery of the resistance heating element 20 is completely in contact with the ceramic substrate 10. Therefore, heat is transmitted uniformly. The wafer 9 is directly placed on the heating surface 10a side of the ceramic substrate 10 or is separated by a predetermined distance (5 to 50) via the separation support pin SP.
00 [mu] m) spaced apart and heated. Heating element 20
Is exposed from the ceramic substrate by the opening. The heating element 20 is connected to a through hole S. The through hole S is connected to the inner wall 40 of the hole that has been made conductive, and the inner wall 40 is connected to the pin 30 via the gold solder 50. Support pins (lifter pins) 80 on the ceramic substrate
Is formed.

(Evaluation Test) As the product of the present invention, four types of aluminum nitride and silicon carbide ceramics each having a heating element pattern formed on the surface and each having a different curvature of the bending pattern were manufactured. Example 1
And 8. Four types of aluminum nitride ceramics and silicon carbide ceramics, each having a heating element pattern formed therein and having different curvatures of the bending pattern, were manufactured, and these were named Examples 9 to 16, respectively. As comparative products, ceramic heaters having a heating element pattern having a substantially right-angled bent pattern as shown in FIG. 6 on the surface and inside were manufactured using aluminum nitride and silicon carbide, respectively, to thereby obtain Comparative Examples 1 to 4. Another comparative product is a ceramic heater of aluminum nitride and silicon carbide having a radius of curvature of 25 mm.
Were formed on the surface and inside, and these were designated as Test Examples 1 to 4. Further, ceramic heaters using an alumina substrate having a heating element pattern formed on the surface and inside were manufactured, and Test Examples 5 to 16 were produced. Furthermore, square ceramic heaters were manufactured from aluminum nitride ceramic and silicon carbide ceramic (both having a pattern formed on the surface). Comparative Examples 5 and 6 were used, and the temperature was raised to 300 ° C. to measure the temperature difference between the four corners and the center. did. During the evaluation test,
For each of the example and the comparative example, a voltage of 30
Heat to 0 ° C, JIS-C-1602 (1980) K
The temperature in the vicinity of the bent portion of the bent pattern and the temperature in the vicinity of the spiral pattern were measured with a thermocouple, and the difference was examined. In addition, the temperature rise time up to 300 ° C. was measured. Table 1 shows the results. Also, the temperature of the ceramic heater was raised to 200 ° C,
This was dropped into water and it was examined whether or not cracks developed in the bent portion.

[0038]

[Table 1]

As is apparent from the results, according to the ceramic heater according to the present invention, the difference between the temperature near the bent pattern in which the radius is drawn and the temperature near the spiral pattern is 5 ° C.
However, according to the ceramic heater used as the comparative example, the difference between the temperature near the right-angled bent pattern and the temperature near the spiral pattern was 10 ° C to 15 ° C.
Therefore, according to the ceramic heater according to the present invention, it has been found that the temperature of the ceramic substrate can be made uniform.
According to this result, in the case of the ceramic heater having the above configuration, the radius of curvature is optimally about 1 to 15 mm. In addition, cracks did not occur in the thermal shock test in the examples, whereas cracks were observed in the comparative examples.
In addition, the following is considered. The radius of curvature is 20m
If m is exceeded, the temperature difference will increase. This is because the pattern formation density decreases. Therefore, the effect of the present invention is remarkable when the radius of curvature is in the range of 0.1 to 20 mm. This effect is more remarkable in aluminum nitride and silicon carbide than in alumina. This is because aluminum nitride and silicon carbide are more excellent in temperature follow-up (that is, shorter in temperature rise time) and are more sensitive to variations in the amount of generated heat.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

The ceramic heater according to the present invention has the following features.
If the electrodes are embedded in the ceramic substrate, it can be used as an electrostatic chuck. Further, the ceramic heater according to the present invention, a conductor layer on the surface of the ceramic substrate,
If an electrode is buried inside, it can be used as a wafer prober.

[0042]

The ceramic heater according to the present invention has a bent portion which bends in a curved shape on the surface or inside of a disk-shaped ceramic substrate mainly made of nitride ceramic or carbide ceramic. No temperature-lowering portion is generated in the portion, and the temperature uniformity is excellent. It is particularly suitable for a disk-shaped ceramic heater.

[Brief description of the drawings]

FIG. 1A is a plan view showing a main part of a ceramic heater according to an embodiment of the present invention, and FIG.
It is the elements on larger scale of the dotted line surrounding of (a).

FIG. 2 is a plan view showing an example of a heating element pattern of the ceramic heater according to one embodiment of the present invention.

FIG. 3 is an enlarged partial view showing a part of a heating element pattern of the ceramic heater according to one embodiment of the present invention.

FIG. 4 is a partial sectional view showing a structure of a ceramic heater according to one embodiment of the present invention.

FIG. 5 is a partially enlarged view showing a part of a heating element pattern of a conventional ceramic heater in an enlarged manner.

FIG. 6 is a plan view showing a main part of a ceramic heater used as a comparative example.

FIG. 7 is a drawing substitute photograph of a square ceramic heater.

FIG. 8 is a drawing substitute photograph of a thermoviewer.

FIGS. 9A and 9B are diagrams showing a configuration in a case where a heating element is integrally formed therein.

[Description of Signs] 100 Ceramic heater 1 Ceramic substrate 2, 31, 31a Heating element pattern ─────────────────────────────── ──────────────────────

[Procedure amendment]

[Submission date] June 4, 2001 (2001.6.4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

Patent application title: Ceramic heater for semiconductor manufacturing and inspection equipment

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater for a semiconductor manufacturing / inspection apparatus mainly used in the semiconductor industry, and more particularly, to a ceramic heater provided with a heating element pattern in which a singular point whose temperature is lowered does not occur. The present invention relates to a ceramic heater for drying.

[0002]

2. Description of the Related Art Semiconductor-applied products are extremely important products required in various industries. A typical example of a semiconductor chip is a silicon wafer obtained by slicing a silicon single crystal to a predetermined thickness. Is manufactured by forming various circuits and the like on this silicon wafer.

In order to form these various circuits, a conductive thin film or the like is formed on a silicon wafer, and then an etching resist made of a photosensitive resin or the like is applied through a mask having a circuit pattern, and pattern etching is performed. I do. When applying this etching resist, since the photosensitive resin is a viscous liquid, it is necessary to dry after the application, and it is usual to place a silicon wafer coated with the photosensitive resin on a heater and heat and dry it. Is being done. In addition, it was necessary to heat the wafer during plasma etching, sputtering, and the like.

A heater of this type for mounting and drying a semiconductor wafer such as a silicon wafer on a heater by heating is conventionally provided with a heating element such as an electric resistor on the back side of an aluminum substrate. Although the thing was used a lot, since the substrate made of aluminum requires about 15 mm in thickness,
Not only is it difficult to handle because of the large weight and bulkiness, but also because it is heating by an electric resistor, the temperature controllability from the viewpoint of temperature followability to the current flow is insufficient, and uniform heating is obtained. It was not easy. Therefore, as disclosed in JP-A-11-40330,
There has been proposed a ceramic heater provided with a linear heating element formed by sintering metal particles or the like on the surface of a plate-like body made of a nitride ceramic or the like.

[0005]

However, when a heating element is formed in such a ceramic heater, if the heating element is formed in a pattern having a bent portion, the temperature of the bent portion decreases, and the surface temperature becomes uneven. However, there was still room for improvement. Such uneven surface temperature was more remarkable in ceramics having higher thermal conductivity such as nitride ceramics.

The present invention uses a ceramic material having a high thermal conductivity as a heater substrate to provide a semiconductor having excellent temperature uniformity.
An object of the present invention is to provide a ceramic heater for a body manufacturing / inspection apparatus .

[0007]

According to another aspect of the present invention, there is provided a ceramic heater for a semiconductor manufacturing / inspection apparatus , wherein a heating element is provided on a surface of a disk-shaped ceramic substrate.
A pattern is formed, and the heating element pattern forming surface
Semiconductor wafer heating on the wafer heating surface opposite to
A ceramic heater for a body manufacturing / inspection apparatus, wherein
The diameter of the lamic substrate is 200 mm or more,
Mick is a nitride ceramic, carbide ceramic alone
Or two or more types, and bend to the outer edge.
A curved pattern is arranged, and the curved pattern has a curvature.
Bending to bend with a radius of 0.1 to 20 mm
It is intended to have a part .

[0008] With this configuration, there is no temperature drop at the bent portion of the heating element arrangement pattern (sometimes called a heating element pattern). If the bent portion does not draw a radius, for example, if it bends at a right angle, the temperature of this right angle portion will drop. In the following description, the heating element pattern is represented by a shape in a top view, but the position in the thickness direction of the ceramic substrate on which the heating element is disposed may not be on the same plane.
It may include a portion that is vertically positioned in the thickness direction.

The present inventors have conducted intensive studies on the causes of the problems according to the prior art, and as a result, have found the following causes. FIG. 5 shows a heating element 32 used in a conventional ceramic heater. As shown in FIG. 5, a part of the heating element is bent at a right angle. Then, the temperature of the right-angled bent portion (arrow 32a) is lower than the temperatures of the other portions. The reason is that the pattern widths h1 and h3 of the substantially straight portion and the pattern width h2 of the right-angled bent portion are different. In the case shown in FIG.
Since the pattern width h2 is larger than the pattern widths h1 and h3, the resistance value of the portion having the pattern width h2 decreases. However, a singular point (spot) whose temperature decreases in the corresponding portion is generated. .

In particular, in the case of a disk-shaped ceramic heater, uniformity of temperature distribution is required unlike a square-shaped ceramic heater. In the case of a square ceramic heater, since the propagation of heat is concentric, the surface temperature at the four corners is reduced, and therefore uniform temperature distribution is not originally required. This is apparent from FIGS. FIG. 7 shows a square ceramic heater.
FIG. 4 is a diagram in which the temperature is raised to 400 ° C. and the surface of a heated surface of an object to be heated such as a wafer is observed with a thermoviewer. As a result, the temperature of the four corners is low, and it can be seen that the rectangular ceramic heater has characteristics not originally required, such as uniformity of temperature distribution. However, in the case of a disc shape, since the temperature distribution can be made uniform, uniformity of the temperature distribution is required, and the semiconductor wafer can be mounted because of the uniformity. For this reason, in such a disk shape, it is necessary to prevent the occurrence of a singular point (spot) whose temperature has decreased.

Therefore, the present inventors have established that the arrangement pattern of the heating element is provided with a bent portion which bends in a round shape as shown in FIG. The inventors have found that the present invention can prevent the reduction of the resistance value and the occurrence of a singular point (spot) having a lowered temperature, thereby completing the present invention.

According to the ceramic heater for a semiconductor manufacturing / inspection apparatus having the above-described configuration, since the bent portion of the heating element pattern is bent in a round shape, the width of the pattern becomes substantially constant. No local temperature drop occurs. Therefore, the temperature of the ceramic heater is made uniform. Incidentally, Japanese Patent Application Laid-Open No. 9-289075, Utility Model Publication No. 3-19292, Utility Model Publication No. 54-12
No. 8945 discloses a rectangular ceramic heater in which a bent pattern portion is formed with a round shape, but this is a square heater and not a disk shape as in the present invention. As a result, the temperatures at the four corners decrease, and temperature uniformity cannot be achieved at all. Also, JP-A-9-827
No. 86 discloses a heater in which a space is formed between a bulk of a heating element and a ceramic substrate, but this does not integrate the ceramic substrate and the heating element as in the present invention. For this reason, since heat is not transmitted in the space, the temperature of the heating surface cannot be made uniform as in the present invention. JP-A-53-6936 discloses an electric heating appliance in which a heating element is arranged on one side of a ceramic heating plate. However, this is used for microwave ovens and electric stoves.In consideration of the effects on the human body and the reactivity of ceramics, water-resistant and non-toxic ceramics such as alumina and silica, that is, oxide ceramics, are used. Therefore, a nitride or carbide ceramic as in the present invention cannot be used. Such an oxide ceramic has poor temperature followability (the temperature does not immediately rise even when the temperature rises). In these documents, the radius of curvature of bending is not described or suggested, and it is added that these documents do not hinder the patentability of the present invention.
Incidentally, the ceramic heater according to the present invention can be used at 150 ° C. to 800 ° C. according to the application. In the present invention, the term “bend” refers to a case where the pattern is substantially parallel before and after the bent portion of the heating element pattern as shown in FIG. 1B, or as shown in FIG. When the pattern forms a right angle, an acute angle, or an obtuse angle, the configuration of the present invention is particularly advantageous because the case where the pattern has an angle before and after the bent portion as in the latter is more likely to cause a temperature drop. .

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a plan view showing a main part of a ceramic heater 100 according to an embodiment of the present invention, and FIG. 1B is an enlarged view of a dotted line in FIG. Things. FIG. 2 is an enlarged view of a heating element pattern provided on the ceramic heater 100, and FIG. 3 is an enlarged view of a part of the heating element pattern. FIG. 4 shows the ceramic heater 10.
FIG. 2 is a partial cross-sectional view showing the structure of No. 0.

In these figures, the ceramic heater 1
Reference numeral 00 denotes a plate-shaped ceramic substrate 1 made of insulating nitride ceramics or carbide ceramics, and a heating element pattern 2 having a specific width on one main surface of the ceramic substrate 1 and having a flat cross section, for example. It is formed as shown in FIG. 1, and a silicon wafer or the like is placed on another main surface and heated.

The shape of the heating element pattern is a linear shape or a wide, substantially straight line or curve. The shape of the cross section of the heating element is not limited as long as it is flat, and may be square, elliptical, or the like. Further, the linear heating element may have a spiral shape. The aspect ratio (width of the heating element / thickness of the heating element) of the cross section of the heating element pattern 2 is desirably 10 to 5000. By adjusting to this range,
This is because the resistance value of the heating element pattern 2 can be increased, and the uniformity of the temperature of the heating surface can be ensured.

Incidentally, when the thickness of the heating element pattern 2 is constant, if the aspect ratio is smaller than the above range, the amount of heat propagation in the wafer heating direction of the ceramic substrate 1 becomes small, and the heating element pattern 2 Approximate heat distribution occurs on the heating surface. Conversely, if the aspect ratio is too large, the temperature immediately above the center of the heating element pattern 2 will be high, and eventually a heat distribution similar to the heating element pattern 2 will be generated on the heating surface. Therefore, in consideration of the temperature distribution, the aspect ratio of the cross section is preferably 10 to 5000.

When the heating element pattern 2 is formed on the surface of the ceramic substrate 1, the thickness of the heating element pattern 2 is set to 1
-30 μm is preferable, and 1-10 μm is more preferable.
When the heating element pattern 2 is formed inside the ceramic substrate 1, the thickness is preferably 1 to 50 μm. A heating element pattern 2 is provided on the surface of the ceramic substrate 1.
Is formed, the width of the heating element pattern 2 is 0.1
-20 mm is preferable, and 0.1-5 mm is more preferable. Further, a heating element pattern 2 is provided inside the ceramic substrate 1.
Is formed, the width of the heating element pattern 2 is 5
~ 20 µm is preferred.

Although the heating element pattern 2 shown in FIG. 1 is a hybrid of a spiral pattern and a bent pattern, it is desirable to dispose the bent pattern at the outer edge. This is because the bent pattern can increase the wiring density, so that the temperature can be suppressed from decreasing near the outer peripheral edge, where the temperature tends to decrease. Further, the heating element pattern 2 may be constituted by only a bending pattern as shown in FIG.

Heating element pattern 2 shown in FIGS. 1 and 2
FIG. 3 shows an example of the bent portion, which has a predetermined width as shown in FIG. Therefore, the pattern width k1, k2, and k3 of the heating element pattern 2 is k1 = k2.
= K3, and the bent portion has a radius of curvature r. Therefore, the heating element pattern 2 has a configuration in which a reduction in resistance due to a difference in pattern width and a generation of a singular point (spot) whose temperature has decreased due to this are prevented.

Here, the material of the ceramic substrate is preferably an aluminum nitride sintered body, but is not limited thereto. In addition, carbide ceramics, oxide ceramics, and nitrides other than aluminum nitride may be used. Ceramics and the like are preferred.

For example, as an example of a carbide ceramic,
Metal carbide ceramics such as silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide can be given, and examples of oxide ceramics include metal oxide ceramics such as alumina, zirconia, cordierite, and mullite. Can be. Furthermore, examples of the nitride ceramic include aluminum nitride as well as metal nitride ceramics such as silicon nitride, boron nitride, and titanium nitride.

Of these ceramic materials, nitride ceramics and carbide ceramics are generally preferable to oxide ceramics in that they exhibit high thermal conductivity. These materials may be used alone or in combination of two or more. For example, an oxide ceramic or a carbide ceramic may be added to the nitride ceramic, or an oxide ceramic or a carbide ceramic may be added to the carbide ceramic. The higher the thermal conductivity of the ceramic, the more the temperature of the bent portion drops significantly, and the greater the effect of the present invention. The thickness of the ceramic substrate of the present invention is desirably 50 mm or less, particularly preferably 18 mm or less. In particular, when the thickness of the ceramic substrate exceeds 18 mm, the heat capacity of the ceramic substrate increases, and particularly when heating and cooling with the provision of a temperature control means, the temperature followability is reduced due to the large heat capacity. is there. Also,
The problem of non-uniform temperature solved by the ceramic substrate of the present invention is because it does not easily occur with a ceramic substrate having a thickness exceeding 18 mm. Particularly, 5 mm or less is optimal. The thickness is desirably 1 mm or more. The diameter of the ceramic substrate of the present invention is desirably 200 mm or more.
In particular, it is desirable to be 12 inches (300 mm) or more. This is because it will become the mainstream of next-generation silicon wafers.
Further, the problem of non-uniform temperature solved by the present invention is that the diameter is 2 mm.
This is because it hardly occurs on a ceramic substrate of 00 mm or less. In the ceramic substrate of the present invention, the ceramic substrate desirably contains 5 to 5000 ppm of carbon. By containing carbon, the ceramic substrate can be blackened, and radiant heat can be sufficiently utilized when used as a ceramic heater. The carbon may be amorphous or crystalline. When amorphous carbon is used, a decrease in volume resistivity at high temperatures can be prevented, and when crystalline one is used,
This is because a decrease in thermal conductivity at a high temperature can be prevented. Therefore, depending on the application, both crystalline carbon and amorphous carbon may be used in combination. Further, the content of carbon is more preferably 50 to 2000 ppm. When carbon is contained in the ceramic substrate,
The brightness is N based on the value of JIS Z 8721.
It is desirable that carbon be contained so as to be 4 or less. This is because a material having such a lightness is excellent in radiant heat and concealing property. Here, the lightness N is 0 for an ideal black lightness, 10 for an ideal white lightness, and a perception of the brightness of the color between these black lightness and white lightness. Each color is divided into 10 so as to have a uniform rate, and is displayed with symbols N0 to N10. The actual measurement of lightness is N0
The comparison is made with the color chart corresponding to .about.N10. In this case, the first decimal place is 0 or 5. In the ceramic substrate of the present invention, in addition to placing the silicon wafer in contact with the wafer mounting surface of the ceramic substrate, the silicon wafer is supported by support pins or the like, and the silicon wafer is connected to the ceramic substrate as shown in FIG. In some cases, a certain interval is maintained. In FIG. 4, the support pins 7 are inserted through the through holes 8 to hold the silicon wafer 9. By moving the support pins 7 up and down, it is possible to receive the silicon wafer 9 from the transfer machine, place the silicon wafer 9 on a ceramic substrate, and heat the silicon wafer 9 while supporting the silicon wafer 9 on pins (not shown). A heating element 2 is formed on the bottom surface of the ceramic substrate, and a metal coating layer is provided on the surface of the heating element 2. A bottomed hole is provided, into which a thermocouple is inserted. In this embodiment, the heating element is formed on the surface of the ceramic substrate, and can adjust the resistance value or blow a cooling gas at the time of cooling, thereby enabling rapid cooling. Further, since the entire region in the thickness direction of the ceramic substrate can be used as a heat diffusion plate, the ceramic substrate can be made thinner and the heat capacity can be made smaller than in the case where a heating element is provided inside, so that rapid temperature rise and fall are possible. The silicon wafer 9 is heated on the wafer heating surface side opposite to the heating element formation surface. Next, a method for manufacturing the ceramic heater 100 according to the present invention will be described. In the following description, the process conditions are merely examples, and are not limited to this embodiment. Therefore, the process conditions are set with appropriate changes depending on the size of the sample, the throughput, and the like.

First, 100 parts by weight of aluminum nitride powder (average particle size: 1.1 μm) and yttria (average particle size: 0.1 μm) were used.
4 μm) 4 parts by weight, 12 parts by weight of an acrylic resin binder, and alcohol were mixed and kneaded, and then granulated by a spray dryer method. Also, when using silicon carbide, silicon carbide powder (average particle size: 1.0 μm)
After mixing and kneading 00 parts by weight, 0.5 parts by weight of C or B ₄ C, 12 parts by weight of an acrylic resin binder, and alcohol, a granular powder was obtained by a spray dryer method. In addition, although alumina is used in a test example and the like described below, in this case, alumina powder (average particle size: 1.0 μm)
And 12 parts by weight of an acrylic resin binder and alcohol were mixed and kneaded, and then a granular powder was formed by a spray dryer method.

Next, the granular powder was charged into a molding die and molded into a flat plate to obtain a formed product. A through hole for inserting a semiconductor wafer support pin into the formed form;
A recess for embedding a thermocouple was formed by drilling.

The formed body in which the through holes and the recesses were formed was hot-pressed at about 1800 ° C. and a pressure of 200 kg / ccm ² to obtain a 3 mm-thick aluminum nitride or silicon carbide plate-like sintered body. This was cut out into a disk shape having a diameter of 210 mm to obtain a ceramic substrate 1 for the ceramic heater 100. After forming an insulating film such as an oxide film on the surface of the ceramic substrate, it is desirable to print a heating element described later. Specifically, a glass paste is applied and 1000 ° C.
There is a method of melting by heating and a method of baking the surface of the ceramic substrate at 500 to 1000 ° C. in an oxidizing atmosphere as described above. In particular, in the case of carbide ceramics, if the purity is low, there is electrical conductivity, so it is desirable to form an insulating film. The thickness of the insulating film is preferably 0.1 to 1000 μm.

A conductive paste was printed on the ceramic substrate 1 by a screen printing method so that the heating element patterns 2 were arranged in the pattern shown in FIG. The conductive paste used here was Solvest PS6 manufactured by Tokuriki Chemical Laboratory.
03D (trade name), and the conductive paste is a metal oxide composed of a mixture of lead oxide, zinc oxide, silica, boron oxide, and alumina (the weight ratio is 5/5 in this order).
5/10/25/10) 7.5% by weight based on the amount of silver
It is a so-called lead-containing silver paste. Incidentally, the average particle size of silver was 4.5 μm, and the shape was mainly flake-like.

The ceramic substrate on which the conductive paste was printed was heated and fired at 780 ° C. to sinter silver and lead in the conductive paste, and baked on the ceramic substrate. At this time, the heating element pattern made of the lead-containing silver sintered body had a thickness of about 5 μm, a width of 2.4 mm, and a sheet resistance of 7.7 mΩ / □. The heating element pattern has a pattern that bends while drawing a radius at an edge portion near the outer periphery. The radius of curvature of the radius is desirably 0.1 mm to 20 mm. If it is too small, it becomes a right angle, and if it is too large, the heating element pattern density cannot be increased. The radius of curvature is defined by the center line (L in FIG. 3) of the heating element pattern.

Next, the concentration per liter was 80 g / l of nickel sulfate and 24 g of sodium hypophosphite.
g / l, sodium acetate 12 g / l, boric acid 8 g / l,
The ceramic substrate is immersed in an electroless nickel plating bath containing an aqueous solution having a concentration of 6 g / l ammonium chloride to deposit a nickel metal layer having a thickness of about 1 μm on the surface of the lead-containing silver sintered body. Thus, a heating element pattern was formed.

As shown in FIG. 1 (a), the heating element patterns 2, 31, 31a are formed on the ceramic substrate 1 in a predetermined pattern as shown in FIG. Metal particles and metal oxide particles can be sintered to such an extent that they are fused together. And
The form of the heating element pattern is, as shown in FIG.
What is necessary is just a width substantially straight line or curve. Therefore, it does not need to be a geometrically strict straight line or curve.

Finally, as shown in FIG. 4, silver-containing lead solder paste (Tanaka Kikinzoku Kogyo Co., Ltd.) is applied by screen printing to a portion where terminal pins 3 for securing the connection between the heating element pattern 2 and the power supply are mounted. )) Printed on the solder layer 6
Further, terminal pins 3 made of Kovar were placed on the solder layer and heated and reflowed at 420 ° C. to attach the terminal pins 3 to the surface of the heating element pattern 2.

Further, a thermocouple (not shown) for controlling the temperature was embedded in the ceramic substrate 1 to obtain a ceramic heater 100 according to the present invention. 4, reference numeral 7 denotes a support pin for supporting the semiconductor wafer 9;
Is inserted through the through-hole 8 formed in the ceramic substrate 1. Since the heating element pattern 2 has a predetermined resistance value, the heating element pattern 2 is energized from a position where a terminal pin 3 for energizing the heating element pattern 2 is attached. Generates heat by Joule heat and heats the semiconductor wafer 9.

Next, a method of manufacturing a ceramic heater (FIG. 9) having a heating element formed therein will be described.

(1) First, a ceramic powder of a nitride ceramic or a carbide ceramic is mixed with a binder and a solvent to obtain a green sheet. As the above-mentioned ceramic powder, for example, aluminum nitride or the like can be used, and a sintering aid such as yttria may be added as necessary. The sintering aid can be adjusted at 0.1 to 10% by weight. The average particle size of the ceramic powder is
0.1 to 10 μm. The binder is preferably at least one selected from an acrylic binder, ethyl cellulose, butyl cellosolve, and polyvinyl alcohol. Further, as the solvent, at least one selected from α-terpineol and glycol is desirable. A paste obtained by mixing these is shaped into a sheet by a doctor blade method to produce a green sheet. Note that alumina powder can be produced under the same conditions.
The green sheet may be provided with a through hole for inserting a support pin of the silicon wafer and a concave portion for burying a thermocouple as needed. The through holes and the concave portions can be formed by panning or the like. The thickness of the green sheet is 0.1
About 5 mm is preferable. Next, a conductor paste to be a resistance heating element is printed on the green sheet. Printing is performed so as to obtain a desired aspect ratio in consideration of the shrinkage ratio of the green sheet. As the conductive ceramic particles contained in these conductive pastes, carbides of tungsten or molybdenum are most suitable. This is because it is hard to be oxidized and the thermal conductivity is hard to decrease. Further, as the metal particles, for example, tungsten, molybdenum, platinum, nickel and the like can be used. The average particle diameter of the conductive ceramic particles and the metal particles is preferably 0.1 to 5 μm. This is because it is difficult to print the conductor paste when these particles are too large or too small. As such a paste, metal particles or conductive ceramic particles 85 may be used.
To 97 parts by weight, 1.5 to 10 parts by weight of at least one kind of binder selected from acrylic, ethyl cellulose, butyl cellosolve and polyvinyl alcohol, and at least one kind of solvent selected from α-terpineol, glycol, ethyl alcohol and butanol. 0.5-1
The paste for conductor prepared by mixing 0 parts by weight is most suitable. Further, a conductor paste is filled into the holes formed by punching or the like to obtain a through-hole print. Next, a green sheet having a printed body and a green sheet having no printed body are laminated. The reason why the green sheet having no printed body is laminated on the side where the resistance heating element is formed is to prevent the end face of the through hole from being exposed and being oxidized during firing for forming the resistance heating element. If baking for forming the resistance heating element is performed while the end face of the through hole is exposed, it is necessary to sputter a metal that is difficult to oxidize, such as nickel, and more preferably to coat it with Au-Ni gold solder. Is also good.

(2) Next, the laminate is heated and pressurized to integrally sinter the green sheet and the conductive paste. Heating temperature is 1000-2000 ° C, pressurization is 1
Preferably 00~200kg / cm ^2, these heat and pressure are carried out in an inert gas atmosphere. As the inert gas, argon, nitrogen, or the like can be used.

(3) Next, a blind hole for connecting an external terminal is provided. At least a part of the inner wall of the blind hole is preferably made conductive, and the conductive inner wall is preferably connected to the resistance heating element 5 or the like (FIG. 9B).

(4) Finally, an external terminal is provided in the blind hole via a brazing filler metal. Furthermore, if necessary, a bottomed hole is provided,
A thermocouple can be embedded therein. Solder is silver-
Alloys such as lead, lead-tin and bismuth-tin can be used. Note that the thickness of the solder layer is 0.1 to 50 μm.
Is desirable. This is because the range is sufficient to secure the connection by soldering. With such a method, the ceramic heater 200 shown in FIG. 9A can be manufactured. In the ceramic heater 200, the resistance heating element 20 is formed integrally with the ceramic substrate 10 inside the ceramic substrate 10, and the periphery of the resistance heating element 20 is completely in contact with the ceramic substrate 10. Therefore, heat is transmitted uniformly. The wafer 9 is directly placed on the heating surface 10a side of the ceramic substrate 10 or is separated by a predetermined distance (5 to 50) via the separation support pin SP.
00 [mu] m) spaced apart and heated. Heating element 20
Is exposed from the ceramic substrate by the opening. The heating element 20 is connected to a through hole S. The through hole S is connected to the inner wall 40 of the hole that has been made conductive, and the inner wall 40 is connected to the pin 30 via the gold solder 50. Support pins (lifter pins) 80 on the ceramic substrate
Is formed.

(Evaluation Test) As the product of the present invention, four types of aluminum nitride and silicon carbide ceramics each having a heating element pattern formed on the surface and each having a different curvature of the bending pattern were manufactured. Example 1
And 8. Four types of aluminum nitride ceramics and silicon carbide ceramics, each having a heating element pattern formed therein and having different curvatures of the bending pattern, were manufactured, and these were named Examples 9 to 16, respectively. As comparative products, ceramic heaters having a heating element pattern having a substantially right-angled bent pattern as shown in FIG. 6 on the surface and inside were manufactured using aluminum nitride and silicon carbide, respectively, to thereby obtain Comparative Examples 1 to 4. Another comparative product is a ceramic heater of aluminum nitride and silicon carbide having a radius of curvature of 25 mm.
Were formed on the surface and inside, and these were designated as Test Examples 1 to 4. Further, ceramic heaters using an alumina substrate having a heating element pattern formed on the surface and inside were manufactured, and Test Examples 5 to 16 were produced. Furthermore, square ceramic heaters were manufactured from aluminum nitride ceramic and silicon carbide ceramic (both having a pattern formed on the surface). Comparative Examples 5 and 6 were used, and the temperature was raised to 300 ° C. to measure the temperature difference between the four corners and the center. did. During the evaluation test,
For each of the example and the comparative example, a voltage of 30
Heat to 0 ° C, JIS-C-1602 (1980) K
The temperature in the vicinity of the bent portion of the bent pattern and the temperature in the vicinity of the spiral pattern were measured with a thermocouple, and the difference was examined. In addition, the temperature rise time up to 300 ° C. was measured. Table 1 shows the results. Also, the temperature of the ceramic heater was raised to 200 ° C,
This was dropped into water and it was examined whether or not cracks developed in the bent portion.

[0038]

[Table 1]

As is apparent from the results, according to the ceramic heater according to the present invention, the difference between the temperature near the bent pattern in which the radius is drawn and the temperature near the spiral pattern is 5 ° C.
However, according to the ceramic heater used as the comparative example, the difference between the temperature near the right-angled bent pattern and the temperature near the spiral pattern was 10 ° C to 15 ° C.
Therefore, according to the ceramic heater according to the present invention, it has been found that the temperature of the ceramic substrate can be made uniform.
According to this result, in the case of the ceramic heater having the above configuration, the radius of curvature is optimally about 1 to 15 mm. In addition, cracks did not occur in the thermal shock test in the examples, whereas cracks were observed in the comparative examples.
In addition, the following is considered. The radius of curvature is 20m
If m is exceeded, the temperature difference will increase. This is because the pattern formation density decreases. Therefore, the effect of the present invention is remarkable when the radius of curvature is in the range of 0.1 to 20 mm. This effect is more remarkable in aluminum nitride and silicon carbide than in alumina. This is because aluminum nitride and silicon carbide are more excellent in temperature follow-up (that is, shorter in temperature rise time) and are more sensitive to variations in the amount of generated heat.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

The semiconductor manufacturing / inspection apparatus according to the present invention
The ceramic heater for use can be used as an electrostatic chuck if electrodes are embedded in the ceramic substrate. Further, the ceramic heater for a semiconductor manufacturing / inspection apparatus according to the present invention can be used as a wafer prober by embedding a conductor layer on the surface of the ceramic substrate and burying electrodes inside.

[0042]

According to the present invention, a ceramic heater for a semiconductor manufacturing / inspection apparatus is provided on a surface of a disk-shaped ceramic substrate.
A heating element pattern is formed, and the heating element pattern
Heat the semiconductor wafer on the wafer heating surface opposite to the forming surface
A ceramic heater, wherein
The diameter is 200 mm or more, and the ceramic is a nitride
Ceramic or carbide ceramic alone or two or more
And a bending pattern on the outer edge
The bending pattern has a radius of curvature of 0.1 to 2
With a bend that bends by drawing a 0mm radius
Good pattern formation density can be obtained
In addition, the temperature followability is excellent, and the temperature lowering portion does not occur in the bent portion, and the temperature uniformity is excellent.

[Brief description of the drawings]

FIG. 1A is a plan view showing a main part of a ceramic heater according to an embodiment of the present invention, and FIG.
It is the elements on larger scale of the dotted line surrounding of (a).

FIG. 2 is a plan view showing an example of a heating element pattern of the ceramic heater according to one embodiment of the present invention.

FIG. 3 is an enlarged partial view showing a part of a heating element pattern of the ceramic heater according to one embodiment of the present invention.

FIG. 4 is a partial sectional view showing a structure of a ceramic heater according to one embodiment of the present invention.

FIG. 5 is a partially enlarged view showing a part of a heating element pattern of a conventional ceramic heater in an enlarged manner.

FIG. 6 is a plan view showing a main part of a ceramic heater used as a comparative example.

FIG. 7 is a drawing substitute photograph of a square ceramic heater.

FIG. 8 is a drawing substitute photograph of a thermoviewer.

FIGS. 9A and 9B are diagrams showing a configuration in a case where a heating element is integrally formed therein.

[Description of Signs] 100 Ceramic heater 1 Ceramic substrate 2, 31, 31a Heating element pattern

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/18 H05B 3/20 393 3/20 393 H01L 21/30 567 F term (Reference) 3K034 AA03 AA04 AA10 AA16 AA21 AA22 AA34 BA06 BB06 BC12 BC16 BC17 JA10 3K092 PP20 QA05 QB04 QB44 QB45 QB76 RF03 RF11 RF17 RF26 RF27 TT30 VV22 5E033 BB02 BB06 BD02 5F046 KA04

Claims (4)

[Claims] 1. A ceramic heater in which a heating element pattern is formed on a surface of a disk-shaped ceramic substrate, wherein the ceramic is a nitride ceramic or a carbide ceramic.
A ceramic heater , wherein the heating element pattern comprises a single or two or more types, and the heating element pattern has a bent portion that bends in a curved manner. 2. A ceramic heater in which a heating element pattern is formed inside a disk-shaped ceramic substrate, wherein the ceramic is a nitride ceramic or a carbide ceramic.
The heating element pattern and the ceramic substrate are integrally formed.
The ceramic heater is characterized in that the heating element pattern has a bent portion that bends in a curved manner. 3. A ceramic heater in which a heating element pattern is formed on a surface of a disk-shaped ceramic substrate, wherein the heating element pattern has a bent portion which bends in a radius, and has a radius of curvature. , 0.1-20 mm. 4. A ceramic heater in which a heating element pattern is integrally formed inside a disk-shaped ceramic substrate, wherein the heating element pattern has a bent portion which bends in a curved manner. A ceramic heater having a radius of curvature of 0.1 to 20 mm.