JPH11176559A - Multiple-layered ceramic heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain rise to a high temperature and control properties due to reduction of leakage current between zones, and enable uniform heating of a wafer and quick convergence, by constituting a conductive ceramics or heater pattern covered with a protective layer by bonding two or more zones on an electric insulation ceramics support substance of a resistance between zones of a specific value within a specific temperature range. SOLUTION: On a surface of a support board 4 such as AlN or BN or the like, a heating layer 5 having a heater pattern of inner and outer zones 3 and 2 of carbons or high-melting point metals or the like to be individually temperature-controlled bonded with each other is covered with a protective layer 6. At each zone boundary part, a resistance between zones is 5×10<3> to 1×10<16> ohms at a heater temperature range of 500 to 1500 deg.C by forming of a zone boundary engraved groove 8 or the like in thickness direction of the support substrate 4, and short-circuit due to dielectric breakdown and a temperature fall due to an increased interval are prevented. Further, support points of the support board 4 are set for only a heater outer periphery instead of every outer zones 3, 2, and influence upon temperature distribution such as wafer is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic heater, and more particularly to a multilayer ceramic heater used in a temperature raising / lowering step in a semiconductor process.

[0002]

2. Description of the Related Art Conventionally, heaters used in a semiconductor process include a support substrate made of sintered ceramics such as alumina, aluminum nitride, zirconia, and boron nitride, and a wire made of a high melting point metal such as molybdenum and tungsten as a heating element. A coil or foil is wound or adhered, and an electrically insulating ceramic plate is mounted thereon. As an improvement, a ceramic heater in which a heating layer made of conductive ceramic is provided on an electrically insulating ceramic support substrate, and a coating of electrically insulating ceramic is provided thereon, has been developed. Improves corrosion resistance.

On the other hand, in the manufacture of semiconductor devices, the diameter of wafers has been increasing, and silicon wafers having a diameter of 200 mm have become mainstream at present, and are expected to have a diameter of 300 mm in 2010. In addition, as the diameter increases, it becomes difficult to ensure performance such as process uniformity with conventional batch processing equipment, and as a solution to this, a process that replaces single-wafer processing, which processes wafers one by one, will be implemented in the future. It is expected to increase.

[0004] Ceramic heaters having low power consumption and high stability as a heating source for the single-wafer processing are greatly expected, and their diameters and performance are also being improved. And since the temperature of the wafer has a great influence on the properties of the film formed on the wafer and the film formation rate,
As the diameter of a wafer increases, how to control the heat uniformity is an important point. Therefore, the ceramic heater as a heating source is, for example, divided into a plurality in the radial direction,
It is necessary to quickly control the temperature in each zone so as to maintain the uniform temperature in response to the temperature change that changes due to the gas supply.

[0005]

However, when zone control is performed in a high-temperature process, the resistivity of the ceramic support substrate itself decreases, so that insulation between the zones becomes a problem, and the heater becomes larger in diameter. Then, since the electric power applied thereto also increases in proportion to the area, a high voltage and a high current are required in some cases. Accordingly, if the leakage current between the zones increases, the controllability in each zone decreases, and it takes time to equalize the temperature of the wafer after the temperature rise and fall in the continuous processing of the semiconductor manufacturing process, and in the worst case, However, there is a danger that the heater may be damaged due to short circuit due to dielectric breakdown between zones, and there is a disadvantage that the temperature cannot be raised to a desired temperature.

Therefore, there is a method in which the heater is completely separated and independent for each zone. However, a support point for supporting the support substrate must be provided for each zone, and heat is radiated through this point. As the temperature near the point decreases, the temperature distribution of the wafer to be heated is significantly deteriorated. Therefore, it is preferable that the number of the support points be set to a minimum number on the outer periphery of the heater, and another measure must be taken for insulation between the zones.

The present invention has been made in order to solve such a problem, and even when temperature control is performed for each zone in a high-temperature process, the leakage current between the zones is small, and the temperature can be raised to a high temperature. It is possible to quickly converge the soaking of the wafer when raising and lowering the temperature of the wafer without deteriorating the controllability in each zone, and to set the support points only on the outer periphery of the heater that does not affect the temperature distribution of the wafer. It is an object of the present invention to provide a body-shaped multilayer ceramic heater.

[0008]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention provides a heater pattern made of conductive ceramic or metal on a surface of an electrically insulating ceramic supporting substrate. But at least 2
In a multilayer ceramic heater of an integral resistance heating type in which a protection layer is formed so as to cover the heater pattern while being joined in a state divided into zones or more, the heater temperature range of the heater pattern divided and arranged in the two or more zones 500 ~
Resistance between each zone at 1500 ° C. is 5 × 10 ³ -1
It is a multi-layer ceramic heater characterized by × 10 ¹⁶ Ω.

With this configuration, even when the temperature is controlled for each zone in the high-temperature process, the leakage current between the zones is small, and the temperature can be raised to a high temperature. Also,
The controllability in each zone is very good, and the uniformization of the wafer can be rapidly converged when the temperature of the wafer rises and falls. Further, it is not necessary to set the support point of the support substrate for each zone, and it is sufficient to set the support point only on the outer peripheral portion of the heater which does not affect the temperature distribution of the wafer.

According to a second aspect of the present invention, a heater pattern made of conductive ceramics or metal is joined to a surface of an electrically insulating ceramics support substrate in a state where the heater pattern is divided into at least two zones. A multi-layer ceramic heater of an integral resistance heating type in which a protective layer is formed by covering the heater pattern, in the thickness direction of the support substrate, at each zone boundary of the heater pattern divided into two or more zones. And a multi-layer ceramic heater characterized by forming a dug groove or a through groove for electrical insulation between zones. According to the third aspect, the dug groove or the through groove has a heater temperature range of 500 to 1500.
Resistance between each zone at 5 ° C is 5 × 10 ³ to 1 × 10 ¹⁶
Ω was formed.

In this way, a heater which is easy to process and has good insulation between zones can be easily manufactured. Then, similarly to the method of completely separating the heaters for each zone and independently, the leakage current between the zones is extremely reduced, the risk of causing dielectric breakdown is avoided, and long-term stable use at high temperatures can be ensured. it can. In addition, the temperature controllability of each zone is excellent, so that the temperature uniformity of the wafer at the time of temperature rise and fall can be quickly converged, and it is not necessary to set the supporting point of the supporting substrate for each zone, and the temperature distribution of the wafer can be improved. Need only be installed on the outer peripheral portion of the heater which does not affect the temperature.

Further, in the invention described in claim 4 of the present invention, the material of the support substrate and the protective layer is AlN, B
N, a composite of AlN and BN, PBN or SiO ₂ , wherein the material of the heater pattern is carbon, a high melting point metal, a high melting point metal alloy, a noble metal or a noble metal alloy. is there.

When the heater is made of the selected material as described above, the formation of the digging groove and the through groove can be easily performed, and a long-life multilayer ceramic heater excellent in mechanical strength, heat resistance and corrosion resistance can be obtained. be able to.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings, but the present invention is not limited thereto. Here, FIG. 1 shows an example of the multilayer ceramic heater of the present invention, wherein (a) is a plan view thereof, and (b) is a longitudinal sectional view of a digging groove provided at the boundary between the inner and outer zones. . 2A and 2B show a multi-layer ceramic heater according to another embodiment of the present invention, wherein FIG. 2A is a plan view thereof, and FIG. 2B is a longitudinal sectional view of a through groove provided at an inner / outer zone boundary. is there. FIG. 3 is a plan view of a conventional multilayer ceramic heater.

[0015] The present inventors have proposed that C
As a result of various studies on insulation breakdown between divided zones in a heater for heating a semiconductor wafer used in a VD apparatus or an etching apparatus, a specific insulation resistance was provided between the zones, and a zone boundary was obtained in order to obtain this resistance value. Thus, the present invention has been completed by conceiving that a digging groove or a through groove should be formed.

1 (a) and 1 (b), a multilayer ceramic heater 1 according to the present invention has a disk-shaped support substrate 4 made of electrically insulating pyrolytic boron nitride on a surface of a conductive pyrolytic graphite. Outer zone 2 and inner zone 3 made
Heater pattern (2 lines in parallel per zone)
Is formed, and a protective layer 6 of the same material as that of the support substrate 4 is formed so as to cover the heat generating layer 5. Terminals 7 are provided at both ends of the heat generating portion. They are connected by bolts and nuts that pass through the terminal holes. In addition, the temperature control when used as a heater can be performed separately for the two areas of the outer zone 2 and the inner zone 3.

FIG. 1B is a longitudinal sectional view at the boundary portion A between the inner and outer zones in FIG. 1A. The heat generating layer 5 on the support substrate 4 is divided into inner and outer zones to form gaps and to be insulated. The divided end surface of the heat generating layer 5 is covered with the protective layer 6. A dug groove 8 described later is formed by cutting the support substrate 4 in the gap formed by the division.

Here, the feature of the present invention is that the electric resistance of the inner / outer zone boundary portion A of the heater pattern is reduced by the heater temperature range 5.
Resistance between each zone at 00 to 1500 ° C is 5 × 10
³ to 1 × 10 ¹⁶ Ω.

In order to prevent a short circuit due to dielectric breakdown between the zones, it is sufficient to increase the interval between the zone boundaries.
The separation lowers the temperature in that space, making uniform heating impossible. In addition, a supporting point must be provided for each of the separated zones, and heat is radiated along the supporting points. Therefore, the temperature in the heat generating layer in the vicinity decreases, and the temperature distribution of the wafer to be heated is significantly deteriorated. Absent.

Therefore, the support point may be provided only on the outer peripheral portion of the heater, which is less affected by the temperature drop due to heat radiation, and as a result of obtaining the resistance for insulating between the zones, the heater temperature range is 500 to 1500. It has been found that the resistance between the zones at ° C. should be in the range of 5 × 10 ³ to 1 × 10 ¹⁶ Ω. If it is less than 5 × 10 ³ Ω, it cannot withstand high voltage and high current at high temperature and there is a danger of dielectric breakdown.
In the case of a high resistance exceeding × 10 ¹⁶ Ω, a certain width (distance) is required even if it depends on an insulating layer or a space in order to have the resistance, and a temperature drop occurs in that part, so that the temperature distribution is not sufficient. Uniformity cannot be avoided.

Next, the heater temperature range of 500 to 150
The resistance between each zone at 0 ° C. is 5 × 10 ³ to 1 × 10
^{According to} the present invention, a digging groove or a through hole for electrical insulation between zones is provided in the thickness direction of the support substrate at each zone boundary of the heater pattern divided into two or more zones. A groove was formed. FIG. 1B shows the state of the digging groove 8 provided at each zone boundary portion A (see FIG. 1A). In this example, the groove depth d of the digging groove 8 is , And the ratio between the groove depth d and the groove width c was set to 1: 1 to cut the groove to obtain a desired resistance value.

FIG. 2 shows an example of a through groove as another embodiment of the present invention. FIG. 2 (b) shows a zone boundary portion B [FIG.
(A)] is a longitudinal sectional view of the through groove 9 provided in this example. In this example, the through groove 9 is penetrated by making the groove depth d equal to the thickness of the support substrate 4 and the groove width c is １ ／. -As d, the groove was cut to obtain a desired resistance value. However, in this example, the length of the through groove is set to about 80% of the entire circumference of the zone boundary portion B, and the remaining about 20% is left without processing to maintain the bonding strength between the terminal portion and the inner and outer zones. .

As described above, by forming a digging groove or a through groove having a desired resistance value along the zone boundary of the support substrate, it is possible to reduce a high voltage and a high current at a high temperature in a minimum gap between the zones. It can be a durable dielectric breakdown prevention barrier. Moreover, the mechanical strength of the supporting substrate is hardly reduced by the groove processing, and the gap is minimized, so that there is almost no adverse effect on uniform heating, and this processing is easy.

As the material of the multilayer ceramic heater to which the present invention is applied, the support substrate and the protective layer are made of a material having a high electrical insulating property, such as AlN, BN, and Al.
A complex of N and BN, PBN or SiO ₂ is suitable. The material of the heater pattern has high heat resistance,
Carbon (graphite) with appropriate resistivity, high melting point metal (iron, copper, nickel, molybdenum, tantalum, tungsten, etc.), high melting point metal alloy (Ni-Cr, Fe-
Cr, Fe-Cr-Al, etc.), noble metals (silver, platinum, rhodium, etc.) or alloys of these noble metals (Pt-Rh, etc.) are preferred.

In the multilayer ceramic heater according to the present invention, except for a part of the metal heat generating layer, all of the supporting substrate, the heat generating layer and the protective layer constituting the heater are manufactured by the chemical vapor deposition method (CVD method). Things. According to the CVD method, a uniform, high-density, high-purity deposited layer can be obtained, the leakage current as a heater is small, the temperature can be raised to a high temperature, the controllability of each zone is good, the uniform heating can be easily performed, and the Stable operation becomes possible.

[0026]

EXAMPLES The present invention will now be described specifically with reference to examples of the present invention, but the present invention is not limited to these examples. (Example 1) By a CVD method, ammonia and boron trichloride were reacted at 1800 ° C. under a pressure of 100 Torr to produce a 2 mm-thick support substrate made of pyrolytic boron nitride, and methane gas was heated at 1650 ° C. Pyrolytic graphite layer having a thickness of 100 μm is formed by thermal decomposition under the conditions of 50 Torr and 50 Torr, and a heater pattern composed of an outer zone 2 (two lines) and an inner zone 3 (two lines) as shown in FIG. 3 is processed. did.
Next, ammonia and boron trichloride were again added to the substrate for 1 hour.
The reaction was performed at 1800 ° C. under a pressure of 00 Torr, and the heating layer was covered with a 100 μm thick protective layer made of pyrolytic boron nitride.
Diameter 250 consisting of two zones, outer zone 2 and inner zone 3
mm multilayer ceramic heater was manufactured.

As shown in FIG. 1, only the zone boundary A of the support base material 4 has a depth (1 mm) of a half of the total thickness of the base material and a width of the same dimension as the depth. (1 mm) digging groove 8 was provided. By this processing, the insulation resistance between the zones at 800 ° C. at the silicon wafer temperature is 6 × 10
It became ³ Ω (about twice as large as that of Comparative Example 1), and it was possible to heat up to 1000 ° C. at the silicon wafer temperature after the temperature rise.

(Comparative Example 1) In the same manner as described above, as shown in FIG. 3, a conventional 250 mm diameter zone consisting of two zones, an outer zone 2 and an inner zone 3, having no groove at the zone boundary. A multilayer ceramic heater was manufactured. Then, while controlling the zone of the multilayer ceramic heater under a vacuum of 10 ^-2 Torr, the silicon wafer was moved 500 times.
Heated to ° C. Then, power was applied to raise the temperature rapidly, and the temperature was raised to 800 ° C. at the silicon wafer temperature. As a result, the leakage current between the inner and outer zones increased, and it was impossible to raise the temperature further. The heater temperature at this time is 12
00 ° C., because the insulation resistance between the zones was reduced, and the resistance between the zones at that time was 3 × 1
0 was ^3.

Example 2 In the same manner as described above, a multilayer ceramic heater having a diameter of 250 mm and having two zones as shown in FIG. 3 was produced. As shown in FIG. 2, a through groove was provided in 80% of the entire circumferential area of the zone boundary B. The remaining 20% has terminals 7 so that the inner and outer zones can be integrally supported.
Left without making a groove near. By this processing, the insulation resistance between the zones at 800 ° C. at the silicon wafer temperature is 15 × 10 ^3, which is about five times that of Comparative Example 1, and it is possible to heat up to 1100 ° C. at the silicon wafer temperature after the temperature rise. .

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same effect. Within the technical scope of

For example, although two examples have been shown above as embodiments of the present invention, the present invention is not limited to such examples, and the shape of the object to be heated and the temperature distribution given to the object to be heated are described. Depending on the shape, the number of divisions of the heater zone, the shape, the heater pattern, etc. are changed, but the insulation groove at the boundary of each zone is a groove if the insulation resistance value is appropriately set within a desired range. The shape and position of are not limited.

In the application of the present invention, it is suitable as a heater for a semiconductor wafer in a CVD apparatus. However, the present invention is not limited to such an example. Used effectively as a heater for semiconductor devices such as dry etching.

[0033]

According to the present invention, when performing temperature control for each zone under a high-temperature process, it is possible to suppress the leakage current between the zones and raise the temperature to a high temperature, and the controllability in each zone is improved. It is good and can quickly converge the temperature uniformity of the wafer, and it is not necessary to set the support point of the support substrate for each zone, and it is installed only on the outer periphery of the heater that does not affect the temperature distribution of the wafer. Thus, a multilayer ceramic heater having excellent long-term stability can be provided.

[Brief description of the drawings]

FIG. 1 is a drawing showing an example of a multilayer ceramic heater of the present invention. (A) Plan view, (b) A section longitudinal section.

FIG. 2 is a drawing showing another example of the multilayer ceramic heater of the present invention. (A) Plan view, (b) B section longitudinal sectional view.

FIG. 3 is a plan view showing an example of a conventional multilayer ceramic heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic heater, 2 ... Outer zone, 3 ... Inner zone, 4 ... Support substrate, 5 ... Heat generation layer, 6 ... Protective layer, 7 ... Terminal, 8 ... Zone boundary digging groove, 9 ... Zone boundary penetration groove. c: zone boundary groove width, d: zone boundary groove depth.

Claims (4)

[Claims] A heater pattern made of conductive ceramics or metal is joined to a surface of an electrically insulating ceramic support substrate in a state divided into at least two zones, and a protective layer is formed to cover the heater pattern. In an integrated resistance heating type multilayer ceramic heater, the resistance between the zones in a heater temperature range of 500 to 1500 ° C. of the heater pattern divided into two or more zones is 5 × 10 ³ to 1 × 10 ¹⁶ Ω. A multilayer ceramic heater characterized by the following. 2. A heater pattern made of conductive ceramics or metal is joined to a surface of an electrically insulating ceramic supporting substrate in a state divided into at least two zones, and a protective layer is formed to cover the heater pattern. In an integrated resistance heating type multi-layer ceramic heater, a digging groove or a through hole for electrical insulation between zones is formed in the thickness direction of the support substrate at each zone boundary of the heater pattern divided into two or more zones. A multilayer ceramic heater characterized by forming grooves. 3. The digging groove or the through groove has a resistance between each zone in a heater temperature range of 500 to 1500 ° C.
^{3. The} multilayer ceramic heater according to claim 2, wherein the multilayer ceramic heater is formed so as to have a resistance of 10 < ³ > to 1 * 10 < ¹⁶ > [Omega]. 4. The material of the support substrate and the protective layer is A
1N, BN, complex of AlN and BN, PBN or S
iO ₂ , wherein the heater pattern is made of carbon,
The multilayer ceramic heater according to any one of claims 1 to 3, wherein the multilayer ceramic heater is a refractory metal, a refractory metal alloy, a noble metal, or a noble metal alloy.