JP2013058627A - Epitaxial growth device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of growing an epitaxial layer having a uniform film thickness by heating a silicon single crystal substrate in a uniform manner by the adjustment of a heat ray from a reflector.SOLUTION: An epitaxial growth device includes: a heater having a plurality of rod-shaped single-body heaters, each disposed on the upper and lower sides of a susceptor and radially arranged into a circular shape; and an upper and a lower doughnut-shaped reflector each disposed on the upper side of the upper heater and the lower side of the lower heater. At least one of the upper and lower doughnut-shaped reflectors includes a convergence reflector plate for converging heat radiation of the heater and a dispersion reflector plate for dispersing the heat radiation. The convergence reflector plate includes a cylindrical concave formed along the rod-shaped single-body heater. The cylindrical concave includes a portion having a cross section of a different curvature radius in the radial direction of the doughnut-shaped reflector.

Description

  The present invention relates to an epitaxial growth apparatus for growing an epitaxial layer on a main surface of a silicon single crystal substrate.

A silicon epitaxial wafer in which an epitaxial layer (silicon single crystal thin film) is formed on the surface of a silicon single crystal substrate by a vapor phase growth method is widely used in electronic devices such as bipolar ICs and MOS-ICs.
In recent years, with the miniaturization of electronic devices and the progress of thinning and increasing the diameter of wafers, in-plane uniformity of the thickness of the formed epitaxial layer has become an important issue. For example, in the manufacture of a silicon epitaxial wafer having a diameter of 200 mm, a single-wafer epitaxial growth apparatus that is relatively easy to control the film thickness distribution and the like is becoming the mainstream instead of the batch processing method for a plurality of substrates. This is to grow an epitaxial layer while holding a single silicon single crystal substrate horizontally on a susceptor in a reaction chamber and supplying a source gas horizontally and in one direction from one end to the other end of the reaction chamber. is there.

Since the growth rate of the epitaxial layer is strongly influenced by the temperature, it is important to control the temperature distribution in the plane of the silicon single crystal substrate in order to improve the uniformity of the epitaxial layer thickness.
There are various heating methods for the epitaxial growth apparatus. In the case of a single-wafer epitaxial apparatus in which a single crystal silicon substrate is epitaxially grown one by one, a heating method using a halogen lamp heater from above and below the silicon single crystal substrate is often used. . When a single-end mold lamp is used as the halogen lamp, the lamps are arranged radially in a row, and behind this lamp is a donut-like shape for reflecting the heat rays from the heater and irradiating the substrate. A reflector is disposed (see Patent Documents 1 and 2). In addition, in order to protect the support shaft of the susceptor and to secure an optical path for temperature measurement, cylindrical reflectors passing through the center of the donut-shaped reflector are also arranged above and below the substrate placed on the susceptor.

JP 2010-147350 A JP-A-4-255214

The donut-shaped reflector placed behind the heater is a cylindrical concave reflector behind the inside lamp that strongly illuminates the vicinity of the center of the substrate. A planar reflector is provided behind.
In the cylindrical concave reflector part of the inside lamp, the light from the lamp is converged, so a band-shaped irradiation surface is formed on the substrate, and the plurality of circularly arranged inside lamp irradiation surfaces are added symmetrically. As a result, the irradiation intensity near the center of the substrate becomes stronger than the periphery. On the other hand, in the planar reflecting plate portion, the light from the lamp is dispersed, so that the dispersed light is reflected by a cylindrical reflector provided on the substrate, and the irradiation intensity near the periphery of the substrate is increased. By adjusting the irradiation intensity of the heater's inside / outside lamp, the temperature distribution in the substrate surface is made uniform, but as described above, near the center of the substrate by the heat rays reflected from the cylindrical concave reflector In this case, the illuminance near the center of the substrate tends to increase rapidly, and even if the illuminance of the inside / outside lamp is adjusted, the illuminance distribution that fluctuates rapidly remains. there were.
As a result, the temperature distribution in the plane of the substrate becomes non-uniform, and the epitaxial layer thickness becomes non-uniform in the plane.

  The present invention has been made in view of the above problems, and it is possible to heat a silicon single crystal substrate uniformly in a plane by adjusting heat rays from a reflector to grow an epitaxial layer having a uniform film thickness. An object of the present invention is to provide a device that can be used.

  In order to achieve the above object, the present invention provides an epitaxial growth apparatus for growing an epitaxial layer on a main surface of a silicon single crystal substrate placed horizontally on a susceptor. A heater having a plurality of rod-shaped single heaters arranged in a circle, and upper and lower donut-shaped reflectors respectively disposed on the upper side of the upper heater and the lower side of the lower heater, the upper and lower donut-shaped reflectors At least one has a converging reflecting plate portion for converging the heat radiation of the heater and a distributed reflecting plate portion for dispersing the heat radiation, and the converging reflecting plate portion is formed along the rod-shaped single heater. An epitaxy characterized in that it has a cylindrical concave surface, and the cylindrical concave surface has a cross-sectional portion with a different radius of curvature in the radial direction of the donut-shaped reflector. To provide a Kisharu growth apparatus.

  With such a cylindrical concave surface of the converging reflection plate portion of the reflector, the irradiation intensity to the central region of the substrate can be adjusted efficiently, and heating can be performed uniformly within the substrate surface. Further, since the light is reflected by the cylindrical concave surface, the heat rays can be effectively reflected to the central region of the substrate. Accordingly, by heating the substrate uniformly in the plane, an epitaxial layer having a uniform thickness in the plane can be grown, so that a high-quality epitaxial wafer can be manufactured.

In this case, it is preferable that the cylindrical concave surface of the convergent reflection plate portion has a gradually increasing curvature radius in section from the outer peripheral end to the inner peripheral end of the reflector.
Thus, if the radius of curvature is increased stepwise, the cylindrical concave surface of the present invention can be easily formed, and the apparatus can effectively adjust the irradiation of heat rays to the substrate.

At this time, it is preferable that the cylindrical concave surface of the convergent reflection plate portion has a radius of curvature of a cross section of the outer peripheral end of the reflector of 70 mm or less and a radius of curvature of a cross section of the inner peripheral end of 100 mm or more.
With such a cylindrical concave surface, the temperature difference in the surface of the substrate can be effectively reduced, and an epitaxial layer having a uniform thickness can be grown in the surface of the substrate.

In this case, it is preferable that the cylindrical concave surface of the convergent reflecting plate portion has an infinite radius of curvature of the cross section of the inner peripheral end of the reflector.
Such a cylindrical concave surface having a straight cross section at the inner peripheral end can be easily formed, and the apparatus can effectively adjust the irradiation intensity to the central region of the substrate.

  As described above, according to the present invention, an epitaxial layer with high film thickness uniformity can be grown by heating uniformly in the substrate surface with a heater, and a high quality epitaxial wafer can be manufactured. .

It is the schematic which shows an example of the epitaxial growth apparatus of this invention. It is the schematic of the heater and donut-shaped reflector of the epitaxial growth apparatus of this invention. It is the schematic which shows partially the doughnut-shaped reflector of the epitaxial growth apparatus of this invention.

Hereinafter, the present invention will be described in detail as an example of an embodiment with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 shows a schematic view of an epitaxial growth apparatus of the present invention.

1 is provided with a susceptor 12 for horizontally arranging a silicon single crystal substrate W in a reaction chamber 11, and the susceptor 12 is supported by a support shaft 13, which is supported by the susceptor 13. And a mechanism (not shown) for rotating 12.
Above and below the susceptor 12, heaters 15 a and 15 b in which single heaters for heating the silicon single crystal substrate W are arranged in a circle are arranged. In addition, cylindrical reflectors 14a and 14b are respectively arranged at the centers of the upper and lower heaters 15a and 15b. The cylindrical reflectors 14a and 14b can prevent the support shaft 13 from being heated and ensure an optical path for temperature measurement.

FIG. 2 is a schematic view of the heaters 15a and 15b viewed from the susceptor 12 side and the donut-shaped reflectors 16a and 16b provided behind the heaters 15a and 15b. The heaters 15a and 15b have a plurality of rod-shaped single heaters 17a and 17b arranged radially in a circle. As the single heaters 17a and 17b, for example, halogen lamps can be used. The single heater 17a, which is an inside lamp that mainly radiates heat rays to the center of the substrate, and the out that radiates heat rays mainly to the periphery of the substrate. Heaters 15a and 15b are formed side by side with a single heater 17b that is a side lamp. The substrate is heated in-plane uniformly by adjusting the irradiation intensity of each of the inside / outside single heaters 17a and 17b.
And the upper and lower donut-shaped reflectors 16a and 16b are arrange | positioned at the upper side of the upper heater 15a, and the lower side of the lower heater 15b, respectively. At least one of the upper and lower donut-shaped reflectors 16a and 16b has a converging reflection plate portion 18a for converging the heat radiation of the heaters 15a and 15b and a dispersion reflection plate portion 18b for dispersing the heat radiation. These convergent reflection plate portions 18a and dispersion reflection plate portions 18b may be formed alternately, or may be formed rotationally or line-symmetrically.

The convergent reflection plate portion 18a has cylindrical concave surfaces 19, 19 'as shown in FIGS. 3 (A) and 3 (B) formed along the rod-shaped single heater 17a, and the cylindrical concave surfaces 19, 19 'Has cross-sectional portions having different radii of curvature in the radial direction of the donut-shaped reflectors 16a and 16b.
Such cylindrical concave surfaces 19 and 19 ′ can effectively converge and reflect the heat radiation from the single heater 17a depending on the shape thereof. In addition, even if the radius of curvature of the cylindrical concave surface is simply increased, the central portion of the substrate is not sufficiently heated, and the temperature of the substrate becomes non-uniform in the plane. If the reflectors 16a and 16b have cross-sectional portions having different radii of curvature in the radial direction, appropriate heating is possible while suppressing the overlap of the strip-shaped irradiation surface near the substrate center due to the reflected heat rays. is there. Therefore, the vicinity of the substrate center is not excessively heated, and the in-plane surface of the substrate can be heated uniformly.

Further, as shown in FIGS. 3A and 3B, the cylindrical concave surfaces 19 and 19 ′ of the converging reflection plate portions 18a and 18′a extend from the outer peripheral end to the inner peripheral end of the donut-shaped reflectors 16a and 16′a. On the other hand, it is preferable that the curvature radius of the cross section is gradually increased.
Thus, by gradually increasing the radius of curvature, the convergent reflecting plate portions 18a and 18'a can be easily formed, and the irradiation of heat rays near the center of the substrate can be effectively adjusted.

The cylindrical concave surface 19 of the convergent reflection plate portion 18a preferably has a radius of curvature of the cross section of the outer peripheral end of the donut-shaped reflectors 16a and 16b of 70 mm or less and a radius of curvature of the cross section of the inner peripheral end of 100 mm or more.
With such a cylindrical concave surface 19, it is possible to effectively converge and reflect the heat radiation from the heaters 15a and 15b, and to suppress excessive irradiation near the center of the substrate.

Further, as shown in FIG. 3B, the cylindrical concave surface 19 ′ of the convergent reflecting plate portion 18′a has an infinite radius of curvature at the cross section of the inner peripheral ends of the donut-shaped reflectors 16′a and 16′b. It is preferable.
When the radius of curvature is infinite, the cross section is a straight line, and a flat surface is formed on the inner peripheral portion of the cylindrical concave surface 19 ′. Thereby, it is difficult to form an overlap of the belt-shaped irradiation surfaces in the vicinity of the center of the substrate, it is possible to sufficiently suppress excessive irradiation, and it is easy to form the cylindrical concave surface 19 ′.

  The convergent reflection plate portion 18a having the cylindrical concave surface 19 may be formed on both the upper and lower donut-shaped reflectors 16a and 16b, or may be formed on only one of them. In the case where it is formed only on one side, the other donut-shaped reflector can be formed, for example, having a flat reflecting plate portion.

Using the above-described epitaxial growth apparatus 10 of the present invention, for example, a silicon single crystal substrate W is placed on a susceptor 12, the substrate W is heated by heaters 15a and 15b, and a source gas such as trichlorosilane is supplied into the reaction chamber 11. The epitaxial layer can be grown while being introduced into the substrate.
With the apparatus of the present invention, the silicon single crystal substrate can be uniformly heated in the plane, so that an epitaxial layer having a uniform in-plane thickness can be grown, and a high-quality epitaxial wafer is manufactured. Can do.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.
Example 1
Using the single wafer epitaxial growth apparatus for a 300 mm diameter wafer shown in FIG. 1, the temperature distribution in the wafer surface when the center temperature of a silicon wafer having a diameter of 300 mm was heated to 1100 ° C. was measured. The measurement was performed by the method described in Japanese Patent Publication No. 07-058730. This is a method for obtaining a wafer temperature by preparing and heating a diffusion wafer having an impurity injection layer formed on the surface by ion implantation and measuring the sheet resistance after thermal diffusion.
The converging reflecting plate portion of the inside lamp of the upper donut-shaped reflector is a reflecting plate portion having a cylindrical concave surface combining two types of curvature radius sections, and the reflecting plate portion of the outside lamp is flat. . In addition, as the lower donut-shaped reflector, a cylindrical concave reflecting plate portion having a uniform curvature radius from the inner peripheral end to the outer peripheral end of the donut-shaped reflector and a flat reflecting plate portion were used. .

In the reflecting plate portion of the inside lamp of the upper donut-shaped reflector, the radius of curvature of the outer peripheral portion of the cylindrical concave surface is 40 mm, and the radius of curvature of the inner peripheral portion of the cylindrical concave surface is 70, 100, 200 mm (FIG. 3 ( A)) and infinity (plane) (FIG. 3B).
The measured results are shown in Table 1. As can be seen from Table 1, the in-plane maximum temperature differences are 10.4, 9.1, 7.4, and 5.3 ° C., respectively, and the curvature radius of the cross section of the inner periphery of the cylindrical concave surface is 100 mm or more and 10 ° C. or less. Thus, the smallest temperature difference was obtained when the inner peripheral portion of the cylindrical concave surface was flat.

(Example 2)
Heating was performed in the same manner as in Example 1, and the in-plane maximum temperature difference of the substrate at that time was measured. However, the inner peripheral portion of the cylindrical concave surface of the reflecting plate portion of the inside lamp of the upper donut-shaped reflector was a flat surface, and the radius of curvature of the cross section of the outer peripheral portion was 55, 70, 100 mm.
The measurement results are shown in Table 1. The in-plane maximum temperature differences of the substrate were 8.7, 9.8 and 11.5 ° C., respectively, and the radius of curvature of the outer periphery of the cylindrical concave surface was 70 mm or less and 10 ° C. or less.

(Example 3)
Heating was performed in the same manner as in Example 1, and the in-plane maximum temperature difference of the substrate at that time was measured. However, the curvature radius of the cross section of the inner peripheral part of the cylindrical concave surface of the reflecting plate part of the inside lamp of the upper donut-shaped reflector was 40 mm, and the outer peripheral part was a plane.
The measurement results are shown in Table 1. In Example 3, the in-plane maximum temperature difference of the substrate was 8.6 ° C., which was 10 ° C. or less.

Example 4
Heating was performed in the same manner as in Example 1, and the in-plane maximum temperature difference of the substrate at that time was measured. However, for the upper donut-shaped reflector, the reflecting plate portion of the inside lamp having a cylindrical concave surface combining three types of curvature radius sections is used, and the inner peripheral portion of the cylindrical concave surface of the reflecting plate portion is flat and the central portion is The radius of curvature of the cross section was 40 mm, and the outer periphery was a flat surface.
The measurement results are shown in Table 1. In Example 4, the in-plane maximum temperature difference of the substrate was 7.2 ° C.

(Comparative example)
Heating was performed in the same manner as in Example 1, and the in-plane maximum temperature difference of the substrate at that time was measured. However, the cylindrical concave surface of the reflecting plate portion of the inside lamp of the upper donut-shaped reflector was used with a uniform curvature radius of 40 mm in cross section.
The measurement results are shown in Table 1. The in-plane maximum temperature difference of the substrate was 12.7 ° C., which was uneven heating.

  The present invention is not limited to the above embodiment. The above-described 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 any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

10 ... epitaxial growth apparatus, 11 ... reaction chamber, 12 ... susceptor,
13 ... Support shaft, 14a, 14b ... Cylindrical reflector, 15a, 15b ... Heater,
16a, 16b, 16'a, 16'b ... donut-shaped reflectors,
17a, 17b: single heater, 18a, 18'a: converging reflector,
18b ... dispersion reflector part 19, 19, '... cylindrical concave surface, W ... silicon single crystal substrate.

Claims (4)

  An epitaxial growth apparatus for growing an epitaxial layer on a main surface of a silicon single crystal substrate placed horizontally on a susceptor, comprising a plurality of rod-shaped single heaters arranged above and below the susceptor and arranged radially in a circle. And upper and lower donut-shaped reflectors respectively disposed on the upper side of the upper heater and the lower side of the lower heater, and at least one of the upper and lower donut-shaped reflectors A converging reflecting plate portion for converging and a dispersive reflecting plate portion for dispersing heat radiation; the converging reflecting plate portion having a cylindrical concave surface formed along the rod-shaped single heater; and the cylindrical concave surface is An epitaxial growth apparatus characterized by having a cross-sectional portion with a different radius of curvature in the radial direction of a donut-shaped reflector.   2. The epitaxial growth according to claim 1, wherein the cylindrical concave surface of the dispersion reflecting plate portion has a radius of curvature of a section that increases stepwise from an outer peripheral end to an inner peripheral end of the reflector. apparatus.   The cylindrical concave surface of the dispersion reflecting plate part has a radius of curvature of a cross section of an outer peripheral end of the reflector of 70 mm or less and a radius of curvature of a cross section of the inner peripheral end of 100 mm or more. 2. The epitaxial growth apparatus according to 2.   4. The epitaxial growth apparatus according to claim 1, wherein the cylindrical concave surface of the dispersion reflecting plate portion has an infinite radius of curvature of a cross section of an inner peripheral end of the reflector. 5.

Images