JP2000164588A - Substrate-heating method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a substrate-heating method and device for beating a substrate so that a temperature distribution within the surface of the substrate becomes uniform, even if there is a temperature distribution within the surface in a substrate-support member for placing and supporting the substrate. SOLUTION: In a method for supporting a substrate and directly or indirectly heating it by a heating means, clearances 15a, 15b, 15c, 15d, and 15e are provided between a substrate-supporting member 12 for supporting a substrate W and the substrate W, the clearances 15a, 15b, 15c, 15d, and 15e are made larger at a region, where the surface temperature of the support member 12 is high and are made smaller at a region where the surface temperature of the support member 12 is low, for heating the substrate W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate heating apparatus suitable for use in an apparatus for performing various processes such as chemical vapor deposition (CVD) on a substrate such as a semiconductor wafer.

[0002]

2. Description of the Related Art In recent years, a CVD (chemical vapor deposition) method has been widely used as one of means for forming a thin film on a semiconductor substrate in a process of manufacturing a semiconductor memory or a device. FIG.
1 shows a configuration of a conventional general CVD apparatus, which is provided with a sealable film forming chamber 1, and a substrate heating device 2 is disposed inside the film forming chamber 1. A reaction gas supply pipe 3 for supplying a reaction gas to the inside of the film formation chamber 1 is connected to an upper portion thereof, and an exhaust pipe 4 for exhausting a gas after the reaction is connected to a side portion thereof. A flow control valve 5 as pressure control means for controlling the pressure in the film forming chamber 1 is provided. In this example, the substrate heating device 2 includes a substrate heater 6 and a susceptor (substrate support member) 7 installed on the upper surface of the substrate heater 6.

Accordingly, the susceptor 7 of the substrate heating device 2
The substrate W is placed and supported thereon, and while controlling the temperature of the substrate W to a constant value, while maintaining the pressure in the film formation chamber 1 constant, a predetermined gas is fixed in the film formation chamber 1 at a constant flow rate. By supplying for a time, a thin film having a predetermined thickness and quality is formed on the surface of the substrate W by chemical vapor deposition.

[0004] A substrate heating device is constituted only by a substrate heater, and a heating plate on the surface of the substrate heater is used as a substrate support member.
Mounting and supporting the substrate W on the surface of the heating plate is also widely performed.

[0005]

However, in such a substrate heating apparatus, since the heating wire embedded in the substrate heater and the unevenness of the heat release are not uniform, for example, the substrate heating device is not suitable for the heating.
When heated to about 00 ° C., the surface of the substrate heater, and thus the surface of the
An in-plane temperature distribution of about 0 ° C. may occur. Therefore, the substrate also has a temperature distribution corresponding to this, and as a result, variations in film thickness and film quality appear. Variations in film thickness and film quality result in lower quality and lower yield of the semiconductor device to be manufactured.

Although the susceptor can be expected to reduce the temperature distribution on the surface of the substrate heater by inserting the susceptor between the substrate heater and the substrate, the susceptor is required to perform sufficiently uniform heat transfer in the in-plane direction. Is insufficient in thickness, and as a result, a distribution corresponding to the temperature distribution on the surface of the substrate heater occurs in the substrate mounting surface of the susceptor.

The present invention has been made in view of the above circumstances, and even if a substrate supporting member for mounting and supporting a substrate has an in-plane temperature distribution, the substrate is heated so that the in-plane temperature distribution of the substrate becomes more uniform. It is an object of the present invention to provide a method and apparatus for heating a substrate.

[0008]

A substrate heating method according to the present invention is a substrate heating method for supporting a substrate and heating the substrate directly or indirectly by a heating means. Providing a gap between the substrate and the substrate, heating the substrate by increasing the gap in a region where the surface temperature of the support member is high, and decreasing the gap in a region where the surface temperature of the support member is low. It is characterized by.

A substrate heating apparatus according to the present invention supports a substrate,
And a substrate heating device for directly or indirectly heating the substrate by a heating means, wherein a concave portion is formed on a surface of the substrate supporting member supporting the substrate so as to form a gap between the substrate and the substrate supported by the supporting member. The size of the gap is set to be large in a region where the surface temperature of the substrate support member is high and small in a region where the surface temperature is low.

The heat transfer between two parallel surfaces facing each other with a certain gap therebetween can be roughly classified into two types, radiation and conduction. Radiation depends on the emissivity and temperature of the plate, independent of the size of the gap, if the gap is sufficiently small relative to the dimensions of the plate. Conduction has no gap dependence when the pressure is small and the mean free path of the gas is larger than the gap (free molecular heat conduction), but otherwise the amount of heat transfer is inversely proportional to the size of the gap. In other words, at 1 Torr, if the gap is smaller than 3 mm, the influence of heat transfer due to conduction increases, and the amount of heat transfer is inversely proportional to the size of the gap. Also, 1
At 0 Torr, the gap that shifts to free molecular heat conduction is 0.
It is about 05 mm. For example, in a pressure range of about 1 to 10 Torr, by changing the gap between the two parallel surfaces in a range of 0.05 or 0.5 to 3 mm, the amount of heat transfer can be changed by the amount of the gap. Therefore, the amount of heat transfer to the substrate can be corrected by setting the size of the gap between the substrate supporting member and the substrate that supports the substrate to be large in a region where the surface temperature of the substrate supporting member is high and small in a region where the surface temperature of the substrate supporting member is low. And the in-plane temperature distribution of the substrate becomes more uniform.

Further, the size of the gap is 0.2 to 2 m.
m is preferably set in the range of m. As a result, it is possible to prevent the heat transfer amount from being reduced and the thermal efficiency from being greatly reduced, and to prevent the influence of the error of the substrate specifications.

A film forming apparatus according to the present invention is arranged in a vaporizer for generating a raw material gas, a film forming chamber for introducing the raw material gas into the inside to form a film on a substrate, and disposed in the film forming chamber. And a substrate heating device according to item 2.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a substrate heating apparatus according to a first embodiment of the present invention. This substrate heating apparatus 10 includes a substrate heater 11 and a susceptor (substrate support member) 12 made of, for example, SiC. The susceptor 12 is placed on the substrate heater 11, and the substrate W is placed on the susceptor 12, and the substrate W is heated.

On the surface of the susceptor 12, support projections 13 are formed at three locations along the circumferential direction, forming a substrate mounting surface P having a circular shape and one step lower than the shape of the substrate W. Furthermore, in the region of the diameter D ₁ of the the central portion, the first recess 14a is formed, between the recess 14a and the substrate mounting surface P, the size (depth) t ₁ is, For example, 1m
the first gap 15a which is set to m occurs, this in a region extending to the same diameter D ₂ and the diameter of the substrate W around the first recess 14a, second recess 14b is formed, the recess between the parts 14b and the substrate mounting surface P, the size (depth) _{t 2} is the second gap 15b is made to occur, which is set to, for example, 0.7 mm.

In this example, the surface temperature of the substrate heater 11 and, consequently, the surface temperature of the susceptor 12 are high when the surface temperature is high at the center and low at the peripheral portion. In the region (center portion) where the susceptor 12 is high, a large gap 15a is generated between the susceptor 12 and the substrate W. In the region where the surface temperature of the susceptor 12 is low (the peripheral portion), the space between the susceptor 12 and the substrate W is formed. Small gap 15b
Is generated, the amount of heat transfer to the substrate W is corrected, the amount of heat transfer becomes uniform over the entire surface of the substrate W, and the in-plane temperature distribution of the substrate W becomes more uniform.

The size of the gaps 15a and 15b is determined, for example, as follows. That is, FIG. 3 shows a calculation example of the heat transfer amount between the hot plate and the substrate when the gap between the hot plate and the substrate and the pressure are changed. At a pressure of 0.1 Torr, heat transfer between the hot plate and the substrate is mainly radiation, and the amount of heat transfer does not change due to a change in the gap. At a pressure of 1 Torr, when the gap becomes smaller than 3 mm (A in the figure), the influence of heat transfer by conduction increases. As the gap becomes smaller, the amount of heat transfer increases, but from 0.5 mm (B in the figure). When it becomes smaller, the conduction mechanism changes to free molecular heat conduction, and the value becomes constant regardless of the gap. Under a pressure of 10 Torr, the amount of heat transfer changes remarkably in a small gap area, and the gap that shifts to free molecular heat conduction is about 0.05 mm (C in the figure).

For example, C for forming a high dielectric or ferroelectric
The pressure range used for VD is generally 1 to 10 Torr. Therefore, the amount of heat transfer between the hot plate and the substrate can be changed by changing the gap between the hot plate as the support member and the substrate in the range of 0.05 or 0.5 to 3 mm.

In practice, the effective change range of the gap varies depending on the type of the atmospheric gas and the emissivity of the hot plate or the substrate. Also,
To increase the thermal efficiency of the apparatus, it is advantageous to reduce the gap between the hot plate and the substrate and increase the amount of heat transfer as much as possible. Therefore, the upper limit of the change range of the gap between the hot plate and the substrate is 2
mm is practical.

On the other hand, the lower limit of the change range is the substrate (wafer)
It is desirable to select the minimum value that is not affected by the error of the specifications. For example, in SEMI M1.9-91, 20
0 mm wafer has a curvature of 65 μm (maximum) and a warp of 75 μm
(Maximum). Furthermore, the wafer may be warped more than the original wafer due to residual stress due to various wafer processes before the present process. Since there is a possibility that the wafer alone has an in-plane gap distribution of about 0.1 mm, it is preferable to form a gap on the substrate mounting surface of the susceptor such that the gap is not affected by the influence. Therefore, the lower limit of the change range is appropriately about 0.2 mm.

Accordingly, the gaps 15a and 15b between the susceptor 12 and the substrate W are in the range of 0.2 mm to 2 mm, and the gaps 15a and 15b are large in a region where the surface temperature of the susceptor 12 is high and large in a region where the temperature is low. By reducing the size, the amount of heat transferred from the susceptor 12 to the upper side can be made uniform, and the temperature distribution in the plane of the substrate W can be made uniform. Therefore, the in-plane uniformity of the film thickness and film quality is improved.

FIGS. 4 and 5 show a substrate heating apparatus according to a second embodiment of the present invention.
The first recess 14 in the region of the diameter D ₃ of the central portion of the second surface
c, and a size (depth) t between the concave portion 14c and the substrate mounting surface P defined by the support convex portion 13, for example.
₃ causes the first gap 15c which is set to 0.5 mm, the second recess 14d is formed in the region extending up to the same diameter D ₄ and the diameter of the substrate W around the first recess 14c Between the recess 14d and the substrate mounting surface P,
For example the size (depth) t ₄ gives rise to a second gap 15d set in 1 mm, to form a third recess 14e further eccentric to the one region, the substrate and the concave portion 14e between the mounting surface P, for example the size (depth) t ₅ is obtained by the so produce a third gap 15e set to 0.7 mm.

In this example, the surface temperature of the substrate heater 11 and, consequently, the surface temperature of the susceptor 12 are low at the center and high at the peripheral edge, but there is a region where the temperature is low at a position partially eccentric. With this configuration, the amount of heat transfer to the substrate W can be uniformly corrected, and the in-plane temperature distribution of the substrate W can be made more uniform.

FIG. 6 is a diagram showing a configuration of a film forming apparatus using the substrate heating apparatus according to the present invention. This film forming apparatus is for forming a high-dielectric or ferroelectric thin film of, for example, barium titanate / strontium. For example, a raw material gas pipe 41 is provided downstream of a vaporizer 40 for vaporizing a raw material. A film-forming chamber (chamber) 42 that can be hermetically sealed is provided, and an exhaust pipe 44 provided with a vacuum pump 43 is connected downstream thereof. This exhaust pipe 44 is connected to the film forming chamber 42.
A flow control valve 45 is provided as pressure control means in the inside. An oxidizing gas pipe 46 for supplying an oxidizing gas such as oxygen is connected to the film forming chamber 42. Further, inside the film forming chamber,
A substrate heating device 10 serving as a substrate heater 11 and a susceptor 12 is disposed, and a gas supply head 48 for injecting a source gas or a reaction gas from a nozzle hole 47 is provided to face the substrate heating device 10.

With the film forming apparatus having such a configuration, the substrate W
Is placed on the susceptor 12, and a mixed gas (reactive gas) of a source gas and an oxidizing gas is injected toward the substrate W from the nozzle hole 47 of the gas supply head 48 while maintaining the substrate W at a predetermined temperature. A thin film is grown on the surface of the substrate W.

At this time, even if a temperature distribution occurs on the surface of the substrate heater 11 and thus the surface of the susceptor 12,
Due to the gaps of different sizes provided between the susceptor 12 and the substrate W, the amount of heat transfer from the susceptor 12 to the substrate W can be made uniform, and the temperature distribution in the surface of the substrate W can be made uniform. Therefore, the in-plane uniformity of the film thickness and film quality can be improved.

In the above-described embodiment, an example is shown in which a susceptor is used as a substrate supporting member and gaps having different sizes are generated between the susceptor and the substrate. The substrate heating device may be configured only by the substrate heater, and the heating plate may be used as a supporting member to generate gaps having different sizes between the heating plate and the substrate.

[0027]

EXAMPLES (Example 1) in the susceptor shown in FIG. 1 and FIG. 2, the diameter _{D 1} on 140 mm, the gap _(t 1)
Is set to 1 mm, the diameter D _{2 is set} to 200 mm, and the gap (t ₂ ) is set to 0.7 mm (Example 1).
In the figure, the substrate mounting surface P is flattened (conventional example)
And created. FIG. 7 shows the result of measuring the temperature distribution in the substrate surface when the wafer with the thermocouple (the substrate for temperature measurement) was placed on these susceptors and the set temperature of the substrate heater was set to 700 ° C. The pressure in the chamber at this time is 1 Torr
r. In the conventional example, as shown in FIG. 7 (b), the distribution was such that the temperature at the center was high and the temperature at the outer periphery was low, and the difference between the maximum and minimum values of the in-plane temperature was about 12 ° C. On the other hand, in the first embodiment, as shown in FIG. 7A, the overall temperature was slightly lower than 10 ° C., but the temperature became relatively flat and the maximum in-plane temperature was increased. The difference between the value and the minimum was about 9 ° C.

(Embodiment 2) In the susceptor shown in FIGS. 4 and 5, the gap of the first area 14c is set to 0.5 mm, the gap of the second area 14d is set to 1 mm, and the gap of the third area 14e is set to 1 mm. One having a thickness of 0.7 mm (Example 2) and one having a flat substrate mounting surface P in FIG. FIG. 8 shows a result of measuring a temperature distribution in a substrate surface when a wafer with a thermocouple (a substrate for temperature measurement) was placed on these susceptors and the set temperature of the substrate heater was set to 700 ° C. The pressure in the chamber at this time is 1 Torr. Note that, in the same figure, the concave portion 1 shown in FIGS.
Areas corresponding to 4c and 14e are indicated by oblique lines.
In the conventional example, as shown in FIG. 8 (b), the center and the orientation flat are placed in the 6 o'clock direction of the watch, and there is a relatively low temperature region near the outer periphery in the 12:00 to 3 o'clock direction. The difference between the maximum value and the minimum value of the in-plane temperature was about 10 ° C. On the other hand, in the second embodiment, FIG.
As shown in (a), although the temperature as a whole was slightly lower than 10 ° C., the temperature distribution was relatively flat, and the difference between the maximum value and the minimum value of the in-plane temperature was about 2 ° C.

[0029]

As described above, according to the present invention,
By setting the size of the gap between the substrate supporting member for mounting and supporting the substrate and the substrate to be large in the region where the surface temperature of the substrate supporting member is high and small in the region where the surface temperature of the substrate supporting member is low, the amount of heat transfer to the substrate is corrected and uniform. Therefore, the in-plane temperature distribution of the substrate can be made more uniform. Therefore, the in-plane uniformity of the film thickness and the film quality can be remarkably improved by using, for example, a film forming apparatus.

[Brief description of the drawings]

FIG. 1 is a sectional view of a substrate heating apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view of a susceptor used in the substrate heating device of FIG.

FIG. 3 is a graph showing a calculation example of a heat transfer amount between the hot plate and the substrate when the gap between the hot plate and the substrate and the pressure are changed.

FIG. 4 is a cross-sectional view (a cross-sectional view along line AA in FIG. 5) of the substrate heating apparatus according to the second embodiment of the present invention.

FIG. 5 is a plan view of a susceptor used in the substrate heating device of FIG.

6 is an overall configuration diagram showing an outline of a film forming apparatus using the substrate heating apparatus shown in FIG.

FIG. 7A is a diagram illustrating a temperature distribution in the first embodiment, and FIG. 7B is a diagram illustrating a temperature distribution in a conventional example.

FIG. 8 (a) is a diagram showing a temperature distribution in Example 2, and FIG. 8 (b) is a diagram showing a temperature distribution in a conventional example.

FIG. 9 is a sectional view showing a conventional CVD apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate heating apparatus 11 Substrate heater 12 Susceptor (substrate support member) 14a, 14b, 14c, 14d, 14e Depressed part 15a, 15b, 15c, 15d, 15e Gap 40 Vaporizer 42 Film formation chamber 48 Gas supply head

Continued on front page F term (reference) 4K030 AA14 BA42 EA01 FA10 GA02 JA03 KA23 KA46 LA01 5F045 AB40 AC11 AD11 AE21 AE23 BB02 DP03 EM02 EM08 EM09

Claims (4)

[Claims] 1. A substrate heating method for supporting a substrate and directly or indirectly heating the substrate by a heating means, wherein a gap is provided between the substrate supporting member for supporting the substrate and the substrate. A substrate heating method comprising: heating the substrate by increasing the gap in a region where the surface temperature of the support member is high, and decreasing the gap in a region where the surface temperature of the support member is low. 2. A substrate heating apparatus which supports a substrate and directly or indirectly heats the substrate by a heating means, comprising: a substrate supporting member for supporting the substrate; A substrate heating apparatus, wherein a concave portion is formed so as to form a gap, and the size of the gap is set large in a region where the surface temperature of the substrate supporting member is high and small in a region where the surface temperature of the substrate supporting member is low. 3. The substrate heating method according to claim 1, wherein the size of the gap is set in a range of 0.2 to 2 mm. 4. The substrate heating device according to claim 2, wherein a vaporizer for generating a raw material gas, a film forming chamber for introducing the raw material gas into the inside to form a film on a substrate, and the substrate heating device arranged in the film forming chamber. And a film forming apparatus.