JPH11204451A - Reflecting plate and heat treatment device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To artificially increase number of light sources and uniformly heat a treatment object, by providing a plurality of reflection surfaces having a concave cross section and constituting a dome shape. SOLUTION: A reflecting plate 1 is in a dome shape formed by vertically cutting an elliptic body having a long-axis length 'b' and a short-axis length 'a' in order to reflect a light from a light source 2. The reflecting plate 1 and a treatment chamber bottom side 17 are worked in mirror surfaces. A treatment object 3 is set on a suscepter 4 and is further set in a colorless transparent quartz chamber 5 in order to prevent contamination from the periphery. A treatment chamber 7 has a circular bottom side so as to increase the uniformity in heating. The light source is arranged concentrically with the treatment object. Thus, the treatment object 3 is uniformly heated. Although the treatment board is macroscopically circular, the surface of the reflecting plate 1 is constituted by a plurality of reflection surfaces, as viewed microscopically. The individual reflection surfaces have a concave cross section and a circular front side, a convex cross section and a circular front side, or a flat cross section and a polygonal front side or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection plate installed in a light irradiation processing apparatus and a heat treatment apparatus using the same. In particular, the present invention relates to a heat treatment apparatus in which the reflection plate is constituted by a plurality of concave surfaces, a plurality of convex surfaces, or a plurality of polygonal reflection surfaces, so that the number of light sources of the heat treatment apparatus can be made virtually infinite. The target is a semiconductor substrate (semiconductor wafer) or a glass substrate.
The present invention relates to a heat treatment apparatus applied to an oxide film forming step, impurity activation, and the like in semiconductor manufacturing.

[0002]

2. Description of the Related Art In recent years, as semiconductor wafers to be processed have become larger, it has become necessary to process semiconductor substrates one by one in order to improve the uniformity of processing between wafers.
For this purpose, a single-wafer heat treatment apparatus is widely used, and a lamp heating method is employed as a heating source for increasing productivity.

Among such heat treatment apparatuses, there is a heat treatment apparatus having the following structure, which has a structure for improving the temperature uniformity in the wafer surface.

A heat treatment apparatus described in FIG. 1 of Japanese Patent Application Laid-Open No. 62-20307 will be described with reference to FIG.
The processing chamber 1 has a closed curved reflecting surface having a spherical inner surface. A light transmission window 7 is formed in the processing chamber 1,
Light emitted from a light source 8 such as a tungsten lamp provided outside the processing chamber 1 is introduced into the processing chamber 1 via an optical system including a predetermined lens group.

In the center of the processing chamber 1, a wafer 13 to be processed
Are supported by a quartz susceptor 12, the light beam is introduced through a light transmission window, and the light beam reflected by the reflection surface R is repeatedly irradiated from all directions, a part of the light beam is absorbed by the wafer 13, and the wafer 13 is absorbed by the wafer 13. Are uniformly heated.

A heat treatment apparatus described in FIG. 1 of JP-A-62-250633 will be described with reference to FIG. This heat treatment apparatus is composed of a reflecting plate 2 having a concave mirror-polished surface and being disposed around the wafer, and two pieces of frosted glass having a concavo-convex pattern disposed between the lamp and the wafer above and below the wafer. The object to be processed is uniformly heated by scattering light using the scattering plates 62 and 65.

[0007]

However, in the heat treatment apparatus shown in FIG. 8, since the light source is introduced through the transmission window, an optical system is required, and the apparatus is complicated and costly. Further, it is difficult to uniformly irradiate the wafer surface with light due to attenuation of the reflected light.

Further, in the heat treatment apparatus shown in FIG. 9, the number of light sources is limited, and even though the scattering plate is sandwiched between the light source and the object to be processed, direct light is used. Therefore, the temperature distribution in the processing chamber occurs, and there is a problem in further improving the uniformity of the in-plane temperature of the semiconductor substrate.

In order to solve these problems, if the number of light sources is increased, the uniformity of heat conduction to an object to be processed will be improved. However, there is a limit in increasing the number of light sources, which leads to an increase in the unit cost of the apparatus.

According to the present invention, a reflector having a plurality of curved reflecting surfaces or a plurality of flat reflecting surfaces is arranged on one surface without requiring a complicated optical system. Accordingly, the first object is to increase the number of light sources in a pseudo manner and to uniformly heat the object to be processed. It is a second object of the present invention to provide a light irradiation heat treatment apparatus using indirect light using innumerable reflecting surfaces instead of direct light.

[0011]

The reflecting plate of the present invention is provided with a plurality of reflecting surfaces having a concave cross section and has a dome shape.

Alternatively, a plurality of reflective surfaces having a convex cross-sectional shape are provided, and are configured in a dome shape.

Alternatively, a plurality of reflecting surfaces having a flat cross-sectional shape and a polygonal front shape are provided and configured in a dome shape.

[0014] The heat treatment apparatus of the present invention comprises: a bottom surface of the processing chamber; a susceptor disposed on the bottom surface of the processing chamber such that the center thereof substantially coincides with the center of the bottom surface of the processing chamber; and a concentric circle from the center of the susceptor. , And a reflector.

A plurality of the light sources are arranged concentrically with respect to the susceptor.

Furthermore, a light-shielding portion is provided between the light source and the susceptor, at a position concentric with the center of the susceptor.

Further, the light-shielding portion has a ring shape.

The reflecting surface having a concave or convex cross section is an elliptical concave or convex cross section, respectively.

Further, the reflection surface is disposed on one entire surface of the reflection plate.

Further, a heat equalizing ring is arranged around the susceptor.

[0021]

According to the light irradiation heat treatment apparatus of the present invention described above, since the shape of the reflector is a plurality of polygons, a plurality of concave surfaces, or a plurality of convex surfaces, the light emitted from the light source is Will reach the object to be processed while being irregularly reflected by the dome-shaped reflector. In other words, when viewed from the object to be processed, the operation is the same as when there are countless light sources. Therefore, the object to be processed can be uniformly heated.

Further, since the light source is disposed between the light source and the object through the light-shielding portion disposed concentrically, the light is not directly irradiated to the object, and the light source is not illuminated. Uniform heating becomes possible.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the light irradiation heat treatment apparatus of the present invention and examples of the shape of the reflection surface of the light irradiation heat treatment apparatus will be described below.

(Embodiment) FIGS. 1 and 2 are sectional views of a processing chamber in a light irradiation heat treatment apparatus as viewed from the side and top, respectively. FIG. 2 is a top sectional view showing the processing chamber in a state where the reflection plate 1 shown in FIG. 1 is removed.

In FIGS. 1 and 2, reference numeral 7 denotes a processing chamber;
Is a reflector, 2 and 8 are light sources, 3 and 9 are workpieces (semiconductor wafers), 4 is a susceptor made of quartz or the like for holding the workpiece, and 5 and 10 are installed around the substrate to be processed. Quartz chambers, 6 and 11 are light-shielding portions for preventing direct light from the light source from hitting the substrate to be processed, and 17 is a processing chamber bottom surface supporting the susceptor 4 and the light-shielding portions 6 and 11.

The susceptor 4 is installed at the center of the bottom surface 17 of the processing chamber, and the workpiece 3 (semiconductor wafer, glass substrate, etc.)
As shown in FIG. 2, the center of the susceptor and the processing chamber is installed such that their centers substantially coincide with each other.

The light shielding portions 6 and 11 are arranged in a ring shape concentrically with respect to the center of the bottom of the processing chamber (or the center of the susceptor). Further, the light shielding unit 6 blocks the direct light from the light sources 2 and 8 so that the processing target 3 does not receive the direct light from the light sources 2 and 8.

The reflecting plate 1 has a dome shape in which an ellipsoid having a major axis length b and a minor axis length a is cut vertically to reflect light from the light sources 2 and 8. It is assumed that the reflection plate 1 and the processing chamber bottom surface 17 are mirror-finished.

The object 3 is placed on the susceptor 4 and
In order to further prevent contamination from the surroundings, it is placed in a chamber 5 made of colorless and transparent quartz.

The processing chamber 7 has a circular bottom in order to increase the uniformity of heating.

The light source 8 is arranged on a concentric circle of the object 9 (or the center of the susceptor 4 and the center of the processing chamber bottom surface 17). As a result, the workpieces 3 and 9 are uniformly heated.

Here, as shown in FIG. 2, the light source 8 is arranged concentrically from the center of the bottom surface of the processing chamber.
Heating can be adjusted by controlling the output of each unit. As a light source, an infrared lamp or the like can be used. In the present embodiment, the light-shielding portion 6 is installed at a position that is concentric with the center of the processing chamber bottom surface 17, but the light sources 2 and 8 are located between the processing chamber center and the light source due to the distance between the processing chamber center and the light-shielding portion 6. It is installed so that the distance between them is long.

The light source viewed from the upper surface of the processing chamber is not limited to a plurality of light sources arranged in a ring shape as in the present embodiment, but may be a ring-shaped light source like a light shielding portion, or a hemisphere on a concentric circle. A plurality of upper light sources may be provided.

When the object to be processed is a semiconductor wafer, in order to improve both the uniformity of the in-plane temperature of the semiconductor wafer and the easiness of replacing the light source, the light source is located at a distance from the center of the bottom of the processing chamber. 8-32 on 20-30cm concentric circles
Are preferably arranged, and the distance between the light sources is
It is preferably about 1 to 3 cm.

The light-shielding portion 6 may be provided so that the direct light from the light sources 2 and 8 is not directly irradiated on the workpiece 3.
In this embodiment, the height is set to 1 to 2 cm from the bottom of the processing chamber, and set to a position of 18 to 28 cm from the center of the bottom of the processing chamber.

(Alternatively, the light-shielding portion 6 is preferably made of a material of the same quality as the processing chamber. The stainless steel is used in this embodiment.) .

FIG. 3 shows the shape of one light source among the plurality of light sources 8 shown in FIG. 2, and shows an example of installation on the bottom of the processing chamber. As shown in FIG. 3, the light source has a U shape. The socket 13 serves as a power transfer unit, and power can be supplied by being inserted into the bottom surface 17 of the processing chamber. In order to prevent the loss of light, all the light emitting portions 12 of the light source 8 are exposed to the processing chamber. With such a U-shape, replacement of the light source becomes easy.

FIGS. 4A and 4B are diagrams showing the fine shape of the reflector 1 of FIG. FIG. 4A shows the reflection plate 14 viewed from the lower surface of the processing chamber.
Although 6 is circular when viewed macroscopically, the surfaces of the reflectors 14 and 16 are composed of a plurality of reflective surfaces 15 when viewed microscopically. Each reflecting surface 15 has a concave cross section as shown in FIG.
As shown in (1), the front is circular, the cross section is convex and the front is circular, or the cross section is flat and the front is composed of a polygon or the like. The shape of the reflection surface will be described later in detail.

In this embodiment, the reflection surface 15 is provided on one surface of the reflection plate 14 without any gap, as shown in FIG.
As described above, by disposing the reflecting surface 15 on the reflecting plate 14 without any gap, light emitted from a limited number of light sources is irregularly reflected, and the number of light sources irradiating the workpiece is simulated. Can be increased. Then, as the number of pseudo light sources increases, the energy of each light beam emitted from each reflecting surface to the object to be processed decreases. That is, the light energy of the plurality of light sources is dispersed,
The object to be processed is evenly irradiated, so that the in-plane temperature uniformity of the object to be processed is ensured.

Further, as shown in FIG. 4, a reflective surface having a circular front surface and a concave or convex cross section is laid so as to fill a gap in the reflective plate 14, and a pattern having a polygonal front surface is a honeycomb-like reflective plate. It is preferable to lay the entire surface without gaps. However, as long as the predetermined in-plane temperature uniformity can be ensured, the reflecting surface may be provided at intervals instead of being provided on the entire reflecting plate.

In the case of an 8-inch semiconductor wafer, it is preferable to set 30 to 800 reflecting surfaces, and in the case of a 12-inch wafer, it is preferable to set 45 to 1200 reflecting surfaces.

Next, with reference to FIGS. 5 to 7, the shape of the reflecting surface 15 constituting the reflecting plate of FIG. 4 will be described in detail. 5, 6 and 7 each have a concave cross section,
The figure shows a convex reflecting surface and a flat reflecting surface.

The reflection surface in FIG. 5 has a circular shape when viewed from the lower surface of the processing chamber with respect to the dome-shaped reflection plate in a direction perpendicular to the dome-shaped reflection plate, and an elliptical concave shape when viewed from the side surface of the processing chamber. You are. FIG. 5A shows the shape as viewed from the front, and FIG.
(B) shows the shape viewed from the cross section. The diameter l of the circle as viewed from the front is 0.5 to 3 cm, and the depth h of the ellipse as viewed from the cross section is 0.2 to 1 cm. When the reflecting surfaces are concave, the individual reflecting surfaces converge and emit the incident light.

The cross-sectional shape may be a perfect hemispherical shape, but an elliptical shape can converge a wide range of light energy to irradiate light. Therefore, from the viewpoint of the uniformity of the in-plane temperature of the object to be processed, the cross-sectional shape is preferably an elliptical shape.

The reflection surface shown in FIG. 6 has a circular (front) shape when viewed from the lower surface of the processing chamber with respect to the dome-shaped reflector, and an elliptical convex shape when viewed from the side surface of the processing chamber. You are. FIG. 6A shows the shape as viewed from the front, and FIG.
(B) shows the shape viewed from the cross section. The diameter l of the circle as viewed from the front is 0.5 to 3 cm, and the depth h of the ellipse as viewed from the cross section is 0.2 to 1 cm. When the reflecting surfaces are convex, the individual reflecting surfaces diverge and emit the incident light.

The side surface shape may be a perfect spherical shape, but an elliptical shape can reduce energy loss between adjacent reflecting surfaces, disperse energy over a wide range of the object to be processed, and emit light. Can be irradiated. Therefore, from the viewpoint of uniformity of the in-plane temperature of the object to be processed and energy efficiency, it is preferable that the cross-sectional shape is an elliptical shape.

The reflection surface in FIG. 7 has a polygonal shape as viewed from the lower surface of the processing chamber with respect to the dome-shaped reflection plate in a direction perpendicular to the dome-shaped reflection plate, and a flat shape as viewed from the side surface of the processing chamber.
FIG. 7A shows a shape viewed from the front, and FIG. 7B shows a shape viewed from the cross section. The polygon forming the reflection surface is triangle to 8
A rectangular area is good. In the case of this embodiment, the reflecting surface has a hexagonal shape, and the incident light is emitted to the object to be processed while acting between the concave surface and the convex surface.

Next, an embodiment in which a heat equalizing ring is provided around the susceptor 4 in FIG. 1 will be described.

The susceptor edge ring has a ring diameter of
It is installed so as to be larger than the diameter of the substrate to be processed. As in the above-described embodiment of the present application, the light source is provided concentrically from the center of the processing chamber bottom surface, a reflecting surface is provided on one surface of the reflecting plate, and the indirect light of the light source is irradiated on the processing object, thereby forming the processing object. Although the uniformity of the in-plane temperature distribution can be improved, the provision of this heat equalizing ring reduces the direct heat transfer from the light source at the edge of the wafer, and further uniformizes the object to be processed. Heat treatment can be performed.

The heat equalizing ring is preferably made of the same material as the object to be processed. When the object to be processed is a semiconductor wafer, it is made of silicon carbonite.
When the soaking ring is installed in a ring shape, it is preferable that the distance between the object to be treated and the soaking ring is not more than 5 mm.

Although not shown in the heat treatment apparatus of FIGS. 1 and 2, the heat treatment apparatus of the present invention is provided with a gas inlet and an exhaust port as appropriate. When the heat treatment apparatus of the present invention is used in an oxide film forming step, a gas inlet is provided at a predetermined position in the chambers 5 and 10, and O ₂ gas is introduced.

Further, when used for annealing for activating impurities or recovering crystal defects, a gas inlet is provided at a predetermined position in the chamber, and nitrogen gas is introduced as a carrier gas.

[0053]

According to the light irradiation heat treatment apparatus, the number of light sources can be increased in a pseudo manner by forming the shape of the reflection plate from a plurality of reflection surfaces, and the uniformity of heating of the object to be processed is markedly improved. Can be improved.

Further, by providing a light shielding portion between the light source and the object to be processed, it is possible to further heat the object to be processed uniformly.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a processing chamber showing one embodiment of a light irradiation heat treatment apparatus of the present invention.

FIG. 2 is a cross-sectional view of a processing chamber showing one embodiment of a light irradiation heat treatment apparatus of the present invention.

FIG. 3 is a diagram showing one embodiment of a light source of the light irradiation heat treatment apparatus of the present invention.

FIG. 4 is a horizontal and vertical sectional view showing one embodiment of a reflector of the light irradiation heat treatment apparatus of the present invention.

FIG. 5 is a view showing one embodiment of a reflecting surface shape of a reflecting plate of the light irradiation heat treatment apparatus of the present invention.

FIG. 6 is a view showing one embodiment of a reflection surface shape of a reflection plate of the light irradiation heat treatment apparatus of the present invention.

FIG. 7 is a view showing one embodiment of a reflection surface shape of a reflection plate of the light irradiation heat treatment apparatus of the present invention.

FIG. 8 shows an example of a conventional light irradiation heat treatment apparatus.

FIG. 9 shows an example of a conventional light irradiation heat treatment apparatus.

[Explanation of symbols]

 1, 14, 16 Reflecting plate 2, 8 Light source 3, 9 Workpiece 4 Susceptor 5, 10 Chamber 6, 11 Light shielding unit 7 Processing room 12 Light emitting unit 13 Socket 15 Reflection surface 17 Processing room bottom surface

Claims (10)

[Claims] 1. A reflector having a plurality of reflecting surfaces having concave cross sections and having a dome shape. 2. A reflector having a plurality of reflective surfaces having a convex cross section and having a dome shape. 3. A reflector having a flat cross section, a plurality of reflection surfaces having a polygonal front shape, and a dome shape. 4. A bottom surface of the processing chamber, a susceptor disposed on the bottom surface of the processing chamber such that the center thereof substantially coincides with the center of the bottom surface of the processing chamber, and a light source disposed concentrically with the center of the susceptor. A heat treatment apparatus comprising: a reflection plate according to any one of claims 1, 2, and 3. 5. The heat treatment apparatus according to claim 4, wherein a light-shielding portion is provided between the light source and the susceptor and concentric with the center of the susceptor. 6. The heat treatment apparatus according to claim 5, wherein said light shielding portion has a ring shape. 7. The heat treatment apparatus according to claim 4, wherein a plurality of said light sources are arranged concentrically with respect to said susceptor. 8. The reflecting surface having a concave or convex cross section,
5. The heat treatment apparatus according to claim 4, wherein each of the cross sections is an elliptical concave or convex surface. 9. The heat treatment apparatus according to claim 4, wherein the reflection surface is disposed on one entire surface of the reflection plate. 10. The heat treatment apparatus according to claim 4, wherein a heat equalizing ring is disposed around said susceptor.