JPH0234164B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a heat treatment target such as a semiconductor substrate (hereinafter referred to as a "wafer") by irradiating it with light.
The present invention relates to a light irradiation type heat treatment apparatus for heat treating wafers.

[Conventional technology]

In general, the heat treatment process for wafers is not limited to heat treatment to activate the ion layer and make it have a uniform composition as a post-treatment of ion implantation or ion vapor deposition, but also heat treatment to stabilize the formation of other films such as silicon films, etc. , is used very widely. In any of these heat treatments, it is necessary to uniformly heat the entire surface of the wafer, and if the wafer is heated unevenly, the required electrical characteristics may not be obtained or the film formation may become unstable. Problems may arise, such as failure to obtain satisfactory ohmic contact.

Therefore, even in conventional light irradiation type heat treatment equipment,
For example, as disclosed in Japanese Unexamined Patent Publication No. 147237/1983, a wafer housed in a heating furnace is moved horizontally. In addition, as shown in the specification of Japanese Patent Application No. 59-30934 filed by the present applicant, by rotating the reflector of the light source that emits infrared rays forward and backward at a predetermined angle, the wafer in the heating furnace can be In order to provide uniform infrared light irradiation, Utility Application No. 1983, also filed by the present applicant,
As shown in the specification of No. 55005, an annular body surrounding the periphery of the wafer is provided on a supporter that holds the wafer in a heating furnace to make the temperature distribution on the wafer as uniform as possible. are doing. Furthermore, Japanese Utility Model Application Publication No. 59-98300 discloses that a filter made of a material such as quartz or wire mesh is interposed between the heater and the wafer to change the thermal energy density received by the center of the wafer. A light irradiation furnace is described in which the surface temperature of the wafer is made substantially uniform, and JP-A-59-101825 discloses a light irradiation furnace in which radiant heat or energy from a light source and energy from a reflector are passed through a diffuser plate to the wafer. A light irradiation type heat treatment apparatus is described that irradiates with light.

FIG. 4 is a sectional view schematically showing the inside structure of a conventional light irradiation type heat treatment apparatus of this kind, in which a wafer 1 is placed on a wafer supporter 2 and carried into a chamber 3 by a driving means 10. This shows the state in which the
This chamber 3 is a box made of quartz and is used to keep the wafer clean in a required gas atmosphere. A light source 4 that emits infrared rays and a light reflecting plate 9 are arranged facing each other on the upper and lower surfaces of this chamber 3 through a predetermined distance, and the wafer 1 is heated from both sides by light irradiation from this heating means. be done. Opening 5 on one side of chamber 3
is sealed by a flange 6, and an inert gas,
For example, _N2 gas is introduced and the gas exhaust pipe 8
is evacuated to the outside of the chamber 3.

[Problem that the invention seeks to solve]

In conventional light irradiation type heat treatment equipment, in order to uniformly heat the entire surface of the wafer including the front and back surfaces and to reduce temperature unevenness, for example, as shown in FIG. The upper light source 4 and the lower light source 4 may be arranged so that their directions are perpendicular to each other, or the transmittance may be changed between the center and the periphery. The wafer is heated through a filter or a diffusion plate. However, in any case, these measures cannot eliminate the temperature difference between the center and the periphery of the upper and lower walls of the chamber, and therefore the radiant heat emitted from the walls of the chamber 3 varies depending on the region. It becomes distinct. As a result, the wafer 1 is directly affected by the radiant heat, or the atmospheric temperature within the chamber 3 becomes uneven, resulting in a problem that the wafer 1 is not heated uniformly. Furthermore, even when the heating by the light source 4 is stopped, the wall of the chamber 3 retains heat for a while, so that the radiant heat from the wall of the chamber is transferred to the wafer.
As a result, it takes time for the temperature of the wafer 1 to drop, and it is difficult to heat treat the wafer 1 with the required temperature rise/fall characteristics. A waiting time was required from one wafer to another wafer 1 to be heat-treated, which caused a problem in productivity.

This invention was made to solve these problems.

[Means for solving problems]

In this invention, as a technical means to solve the above problems, a flat part larger than the wafer is provided between the wafer (substrate to be processed) carried into the chamber and held therein, and the wall surface of the chamber. An intermediate member made of a plate-like body made of quartz and absorbing infrared rays having a wavelength longer than the required wavelength was disposed close to the wafer so that the intermediate member covered the wafer surface. That is, the light irradiation type heat treatment apparatus according to the present invention includes a chamber for heat-treating a wafer in a required atmosphere, and a chamber that is placed outside the chamber and carried into the chamber by irradiating light through the wall surface of the chamber. A heating light source that heats the wafer, and a heating light source that holds the wafer within the chamber.
and a transport holding means for moving the wafer in and out of the chamber, wherein the wall surface of the chamber is made of a material that emits infrared rays with a wavelength longer than the required wavelength for heating the wafer by light irradiation from the light source. In the light irradiation type heat treatment apparatus, the intermediate member is preferably wired close to the wafer surface so as to cover the wafer housed in the chamber.

Here, it is preferable that a plurality of holes are formed in each intermediate member.

[Effect]

When the wafer housed in the chamber is heated by irradiating light (mainly infrared rays with a wavelength of 1 to 3 μm) using a heating means so that the surface temperature of the wafer reaches approximately 1000°C, the wall surface of the chamber is heated by several hundred wafers. The chamber is heated to a temperature of 0.degree. C., and as a result, radiant heat is emitted from the wall of the chamber. At this time, the surface temperature of the wall surface of the chamber is uneven, and therefore the radiant heat radiated from the wall surface also varies depending on the location. However, as can be seen from Figure 5, most of the radiant heat emitted from objects with surface temperatures of several hundred degrees Celsius is due to infrared rays with a wavelength λ of 4 μm or more.On the other hand, the transmittance of quartz is shown in Figure 6. As shown by the curve, only infrared rays with wavelengths in the range of 1 to 4 μm are transmitted, and infrared rays with wavelengths of 4 μm or more are hardly transmitted but absorbed. The intermediate member is manufactured using a material such as quartz that hardly transmits infrared rays with a wavelength of 4 μm or more, but transmits the light rays from the heating means, and as in the present invention, the wafer and the inner wall surface of the chamber are connected. By placing an intermediate member in between, the
Even if temperature unevenness occurs between the front and rear chamber wall surfaces, most of the radiant heat from the wall surfaces will be absorbed by the intermediate member. The wafer is not immediately affected by the radiant heat. Therefore, the wafer is heated only by the action of infrared rays from the light source without being affected by radiant heat from the chamber walls.

Furthermore, if you continue to irradiate infrared light from a light source,
There may be some doubt that some of the intermediate members will reach a temperature of several 100 degrees Celsius and emit radiant heat, resulting in non-uniform heating of the wafer, but such inconvenience does not occur. Of the infrared rays emitted from the light source, the relatively long infrared rays that heat the intermediate member are already absorbed by the chamber walls made of quartz, so the infrared rays that reach the intermediate member are transmitted through the intermediate member. Depending on the light source, the intermediate member will hardly be heated. In addition, the intensity of the infrared rays from the light source that heats the chamber wall is not as strong as the radiant heat from the chamber wall to the intermediate member, and if a certain distance is maintained between the chamber wall and the intermediate member, the intermediate member will not be as hot. do not become.
Even if the intermediate member were to reach a certain degree of high temperature, it does not have as large a heat capacity as the chamber wall surface and is small in size, so there is almost no temperature unevenness, so the temperature of the wafer will not become uneven.

In addition, in the light irradiation type heat treatment apparatus according to the present invention, as described above, most of the radiant heat from the chamber wall surface at a temperature of around several hundred degrees Celsius is absorbed by the intermediate member, so after the heating by the light source is stopped, the wafer No radiant heat is supplied to the

Additionally, when multiple holes are formed in each intermediate member, the inert gas supplied into the chamber is rectified as it passes through the many holes, and the gas flow to the wafer surface is uniform. Become.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a sectional view showing the main parts inside a light irradiation type heat treatment apparatus furnace, which is an embodiment of the present invention. The chamber 3 is made of quartz glass and has an opening 5 on one side thereof, and the wafer 1 placed on the wafer supporter 2 is carried into the chamber 3 through the opening 5 by the movement of the transfer device 10. , and is carried out. An inert gas supply pipe 11 is connected to the other side of the chamber 3, and the inert gas that has been precisely filtered is fed into the chamber 3 through the supply hole 12, and is exhausted from the discharge pipe 11'. The pressure inside the furnace is kept higher than the pressure outside the furnace. The position and direction of the supply hole 12 are determined so as to minimize the influence of the gas flow on the surface of the wafer 1 to prevent local cooling of the wafer 1 from occurring. Others, light source 4,
The arrangement of the light reflecting plate 9 and the flange 6 is the same as that described with respect to FIG. 4 above.

In the light irradiation type heat treatment apparatus according to the present invention, a pair of intermediate members 13 and 13' are provided between each inner wall surface of the chamber 3 and the wafer 1, preferably close to each of the front and back surfaces of the wafer 1, and They are attached almost parallel. In the embodiment shown in FIG. 1, the intermediate members 13, 13' are made of quartz supports 2
8 and 28' are connected to and supported on each inner wall surface of the chamber 3. In addition, intermediate members 13, 13'
is made of quartz (or a material that exhibits similar infrared transmission characteristics), and its thickness is equal to that of chamber 3.
The thinner the wall thickness, the smaller the amount of radiant heat from the intermediate member itself, and the more uniform the surface temperature, which is preferable. The shape of the plane portion of the intermediate members 13, 13' may be similar to the wafer 1, for example, a circle, or may be a polygon such as a quadrangle. The area of the flat portion is made large enough to cover the entire surface of the wafer 1.

FIG. 2 is a perspective view showing the main parts (the light source is omitted in the illustration) of a light irradiation type heat treatment apparatus according to another embodiment of the present invention. In this embodiment device, the pair of intermediate members 13 and 13' are connected to the support rod 1 of the supporter 2.
4 through a side plate 15, and the wafer 1 is supported by a support pin 16 protruding from a lower intermediate member 13'. A large number of holes 17 for rectifying the inert gas sent from the supply pipe 11 are bored in the pair of upper and lower intermediate members 13, 13'. Further, the support rod 14 has a gas supply/exhaust hole 18 penetrating through its shaft portion, and a flange 6 that serves as a door for the chamber 3 is fixed to a part of its outer surface.

On the other hand, a U-shaped frame 19 is attached inside the chamber 3, and when the wafer 1 is placed and the pair of intermediate members 13, 13' are inserted into the chamber 3, the frame 19 and the pair of intermediate members 13, 13' are inserted into the chamber 3. Part 1
3 and 13' are engaged, the frame 19 forms a side surface, and the intermediate members 13 and 13' form an upper surface and a lower surface, respectively, forming an internal chamber as a whole. A support rod 20 that holds the frame 19 within the chamber 3 is provided with an air supply hole 21 in its shaft portion.

In the embodiment apparatus shown in FIG. 2, the air is exhausted from the gas supply/exhaust hole 18 and the air supply hole 21 immediately before and during the heat treatment, but the wafer 1 after the heat treatment is carried out of the chamber 3. At this time, if the inert gas is blown out toward the wafer 1 between the pair of intermediate members 13 and 13' from the gas supply/exhaust hole 18 provided in the support rod 14, the intermediate member 1
3, 13' and wafer 1 are quickly cooled,
Further, it is advantageous that dust in the outside air can be prevented from flying and adhering to the surface of the wafer 1.

Next, FIG. 3 is a sectional view showing still another embodiment of the present invention. In this embodiment, a square internal chamber 22 is arranged within the chamber 3,
A wafer 1 placed on a supporter 2 and carried into the chamber 3 is surrounded by a wall surface. Both upper and lower walls of the internal chamber 22 are formed by a pair of intermediate members 13, 13', and holes 17 are bored in the intermediate members 13, 13' to serve as passages for inert gas. of the inner chamber 22;
The opening on the insertion port side of the wafer 1 is sealed by a flange 23 fixed to the support rod 14, and a flange 6 that closes the opening 5 of the chamber 3 is fixed to the support rod 14, and the wafer supporter It is connected to the drive means 10. Further, a gas exhaust pipe 24 is provided near the opening 5 of the chamber 3, and a gas supply pipe 25 is communicated with the other side of the chamber 3. The holding rod 26 of the internal chamber 22 is inserted into the gas supply pipe 25 and fixed, and the axial center of the holding rod 26 is provided with the internal chamber 22.
A gas supply/exhaust hole 27 communicating with is bored.
If the gas supply/exhaust hole 27 is used to exhaust air from the internal chamber 22 or supply an inert gas to the internal chamber 22 as necessary, for example, when starting heat treatment, the internal chamber 22
Unnecessary air inside 2 can be removed extremely quickly, improving work efficiency.

Furthermore, when the wafer 1 is carried out from the internal chamber 22 and the chamber 3, if an inert gas is blown into the chamber 3 through the gas supply/exhaust pipe 24 described above, the outside air will be inside the internal chamber 22. Since there is no inflow, contamination of foreign matter can be avoided, and the surface of the wafer 1 is cooled by the blown active gas during unloading, allowing a smooth transition to the next process.

In the embodiment shown in FIG. 3, since the wafer 1 is housed in the internal chamber 22, the inert gas supplied into the chamber 3 through the gas supply pipe 25 is supplied to the intermediate member 13, 13'
After passing through the hole 17 drilled in the hole 17, it touches the surface of the wafer 1, and the atmosphere around the wafer 1 becomes uniform. Incidentally, the above-mentioned effects are similarly achieved in the embodiment device shown in FIG. 2 described above.

Although not particularly illustrated, it goes without saying that the present invention can be applied to a so-called in-line heat treatment furnace, in which wafers are loaded into the chamber from one side and are unloaded from the other side after processing. . In each of the above-mentioned embodiments, the transport and holding means is composed of a support for holding the wafer and a transport device for transporting the support into and out of the processing furnace. The conveying/holding means may be a device that holds and conveys the wafer by blowing out pressurized inert gas to the lower surface and using the blowing pressure, and the present invention is not limited to the conveying/holding means.

Further, as long as the intermediate member 13 is a plate-shaped member, its shape is not limited to a flat plate shape, and may be, for example, a curved shape such as an arch shape or a spherical shape such as a dome shape. The arrangement of the intermediate member 13 is not limited to being parallel to the wafer, but may be arranged at a slight angle. The best shape and arrangement of the intermediate member 13 cannot be determined, but the direction of gas flow determined by the shape of the chamber 3, the arrangement of the inert gas supply pipe 11, etc. should be considered. It is selected by

Further, in each of the above embodiments, the intermediate members 13 and 13' are provided on both the front and back sides of the wafer 1, but for example, the heating means is installed only on one side of the wafer 1, and the heating means is installed on the other side. If the wall surface of the chamber is completely cooled and does not emit radiant heat, it is sufficient to arrange the intermediate member only on the side where the heating means is located.

In each of the above embodiments, the pipes for supplying or exhausting gas are not limited to the positions shown in the figures. In short, before heating the wafer, the air surrounding the wafer is quickly evacuated and replaced with the required gas, so that the required gas can be uniformly supplied to the entire surface of the wafer during heating, and preferably It is only necessary that the gas be cooled by the gas.

〔effect〕

Since the present invention has the above configuration, it has the following effects.

(i) Most of the radiant heat from the walls of the chamber is blocked by the intermediate member, and the wafer is not thermally affected by the radiant heat, making it possible to uniformly heat the entire wafer surface. and improve product quality. Furthermore, if a large number of small holes are formed in the intermediate member, the inert gas supplied into the chamber will come into contact with the wafer surface after passing through the small holes, which will equalize the effect of the gas flow. Therefore, the above effects can be further promoted.

(ii) Since the radiant heat from the wall surface of the heat treatment furnace is absorbed by the intermediate member, when the light irradiation from the light source is stopped, no radiant heat is supplied to the wafer, and the wafer cools down relatively quickly. The machine descends and transitions smoothly to the next process, allowing you to immediately start the next process.
A series of work efficiency will be improved. Further, even if a wafer to be heat-treated next is immediately placed in the heat treatment furnace before it has cooled down, the wafer will not be heated by the radiant heat from the furnace wall before the heating means is driven. Therefore, the processing efficiency of the heat treatment apparatus itself is also improved. Moreover, since the wafer can be rapidly heated and rapidly cooled, heat treatment can be performed without changing the concentration distribution of the substance injected into the wafer in the diffusion layer, and thereby an improvement in yield can be expected.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main parts inside the furnace of a light irradiation type heat treatment apparatus showing one embodiment of the present invention, and FIG. 3
This figure is a cross-sectional view of the inside of a furnace of yet another embodiment of the present invention, and FIG. 4 is a cross-sectional view of the inside of a conventional light irradiation type heat treatment apparatus. Also, Figure 5 shows
FIG. 6, which is a diagram showing the relationship between the wavelength of radiated infrared rays and radiant heat at each surface temperature of an object, is a curve showing the relationship between wavelength and transmittance in quartz. 1... Wafer (substrate to be processed), 2... Supporter,
3... Chamber, 4... Light source, 9... Light reflecting plate, 10... Drive means, 13, 13'... Intermediate member, 17... Hole, 22... Internal chamber, 27
...Gas supply and exhaust hole.

Claims (1)

[Claims] 1. A chamber for heat-treating a substrate to be processed in a required atmosphere, and a chamber disposed outside the chamber to irradiate a substrate to be processed into the chamber by irradiating light through the wall surface of the chamber. A heating light source that heats the substrate, and a conveying and holding means that holds the substrate to be processed in the chamber and takes the substrate into and out of the chamber, and the wall surface of the chamber is heated by the light irradiation from the light source. In a light irradiation type heat treatment apparatus made of a material that emits infrared rays with a wavelength longer than the required wavelength for heating the substrate by light irradiation, the inner wall surface of the chamber and the substrate to be processed are arranged so as to cover the substrate to be processed held in the chamber. A light irradiation type heat treatment apparatus characterized in that an intermediate member, which is made of a plate-like quartz body having a flat surface larger than the substrate to be processed and absorbs infrared rays having a wavelength longer than a required wavelength, is disposed between the parts. 2. The light irradiation type heat treatment apparatus according to claim 1, wherein the intermediate member is provided with a plurality of holes. 3. The light irradiation type heat treatment apparatus according to claim 1 or 2, wherein the intermediate member is disposed on both the front and back surfaces of the substrate to be processed. 4. The light irradiation type heat treatment apparatus according to any one of claims 1 to 3, wherein the intermediate member is connected and fixed to the inner wall of the chamber. 5. The conveying and holding means includes a supporter that holds the substrate to be processed and a conveyance device that takes this supporter into and out of the chamber, and the intermediate member is attached to this supporter. The light irradiation type heat treatment apparatus according to any one of Item 3. 6. The light irradiation type heat treatment apparatus according to any one of claims 1 to 3, wherein an internal chamber is formed that surrounds a substrate to be processed within the chamber so that the intermediate members serve as upper and lower wall surfaces. 7. The light irradiation type heat treatment apparatus according to claim 6, wherein the internal chamber is connected to piping for supplying or exhausting air.