JP2000315658A - Thermal treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heat a body to be treated in a state where a temperature distribution on the surface of a mounting stand is relieved by installing a soaking plate on the upper face of the mounting stand. SOLUTION: A film forming device 10 has a treatment container 12 formed in a cylindrical form with aluminium, for example. A mounting stand 26 raised from the base part through a pole 24 is installed in the treatment container 12 for placing a semiconductor wafer W as a body to be treated. A thin soaking plate 34 is placed on the mounting stand 26 and the treated semiconductor wafer W is directly placed on the mounting stand 26. The diameter of the soaking plate 34 is set to be almost similar to that of the mounting stand 26 below the plate. Guide rings 36 which are formed of Al2O3 and whose cross sections are L forms are loaded at the peripheral edge parts of both parts, and the soaking plate 34 is fixed to a mounting stand 26-side. The soaking plate 34 is formed of the discoidal quartz or sapphire plate whose thickness is about 0.5 to 1.5 mm. Radiation energy is multiplexed/reflected at the inner part and radiation heat is dispersed to a periphery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for performing a heat treatment such as a film forming process or an annealing process on a semiconductor wafer.

[0002]

2. Description of the Related Art Generally, in order to manufacture a semiconductor integrated circuit, various heat treatments such as film formation, etching, oxidative diffusion and annealing are repeatedly performed on a semiconductor wafer.
For example, CVD for depositing a film on each wafer
(Chemical Vapor Deposition
n) In the apparatus, a semiconductor wafer is mounted on a mounting table such as a susceptor having a built-in heater, and a processing gas for film formation is supplied while heating the semiconductor wafer to a predetermined temperature to deposit a film on the wafer surface. It is made to let. This will be described with reference to FIG. FIG. 9 is a schematic configuration diagram showing a conventional general heat treatment apparatus. This heat treatment apparatus has a substantially cylindrical processing vessel 2 which can be evacuated. A mounting table 4 for mounting the semiconductor wafer W on the upper surface is installed in the processing container 2, and a processing gas such as a film forming gas is supplied into the processing container 2 on a ceiling facing the mounting table 4. A shower head section 6 for supplying is provided.

The mounting table 4 is entirely made of ceramics such as AlN (aluminum nitride), and heaters 8 made of a resistor such as a molybdenum wire are embedded in the inside thereof in a predetermined pattern. I have.
Specifically, when the mounting table 4 is manufactured, a so-called hot press method is used. For example, a heater 8 arranged in the above-mentioned pattern shape is buried in a raw material powder of ceramics. The ceramics are sintered while maintaining the high temperature in the added state. Then, a vacuum is drawn to a predetermined pressure while supplying the processing gas into the processing container 2,
The wafer W is directly placed on the mounting table 4 formed as described above, and a film forming process is performed while the wafer W is heated by the heat from the heater 8.

[0004]

When performing a heat treatment on the wafer W, it is necessary to maintain a high uniformity of the heating temperature of the wafer W in order to secure the uniformity of the heat treatment in the surface. is necessary. However, the performance of the heater 8 embedded in the mounting table 4 varies, or the pressure at the time of hot pressing varies. There is a problem that a portion having a different calorific value is partially generated on the surface of No. 4 and a temperature distribution is generated.
Then, the temperature distribution on the surface of the mounting table 4 is reflected on the wafer W placed directly on the upper surface, and therefore, the in-plane temperature of the wafer W becomes non-uniform, causing variations.
There has been a problem that the in-plane uniformity of the temperature cannot be sufficiently ensured. The temperature variation on the mounting table surface may be caused by a difference in the heat conduction state on the mounting table surface due to uneven in-plane pressure during hot pressing, or the material of the heater 8 during hot pressing. It is presumed that, for example, molybdenum diffuses non-uniformly into aluminum nitride, which is a ceramic material.

Therefore, in order to improve the non-uniformity of the temperature within the wafer surface as described above, a plurality of short pins, for example, about three pins having a height of several mm, are provided upright on the surface of the mounting table 4. By supporting the wafer W on the pins,
Although the temperature distribution on the upper surface of the mounting table 4 is eased by avoiding the direct mounting of the wafer on the mounting surface, in this case, the film forming gas wraps around the back surface of the wafer W. However, an unnecessary film that causes particles to be generated in a subsequent process adheres to the back surface, which is called a back surface deposition, which is not a preferable measure. In particular, as the wafer size is increased from 6 inches or 8 inches to 12 inches, the above-mentioned problem becomes remarkable, and an early solution is desired. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a heat treatment apparatus capable of heating an object to be processed in a state where the temperature distribution on the surface of the mounting table is relaxed.

[0006]

According to the invention defined in claim 1, a mounting table for mounting an object to be processed is provided in a processing container, and a predetermined heat treatment is applied to the object to be processed. In the heat treatment apparatus, a soaking plate is provided on the upper surface of the mounting table. Thereby, the heat energy is dispersed by multiple reflection of the radiant energy in the thin soaking plate, and the heat energy is transmitted to the object to be processed in a state where the in-plane uniformity of the temperature of the mounting table surface is relaxed. It becomes possible.

In this case, for example, the mounting table is formed by embedding a heater in ceramics. Further, as specified in claim 3, at least one of the front surface and the back surface of the soaking plate may be roughened. By performing the surface roughening process in this manner, the reflectance of radiant energy on the rough surface of the temperature equalizing plate increases, the frequency of multiple reflections in the temperature equalizing plate increases, and the temperature unevenness on the surface of the mounting table. It is possible to transmit heat energy to the object to be processed in a state in which is further reduced.

In addition, the heat equalizing plate may have a distribution in the surface roughening treatment according to the temperature distribution on the surface of the mounting table. In this way, by giving the surface roughening treatment a distribution, it is possible to further improve the in-plane non-uniformity of the temperature of the object to be processed. Further, as specified in claim 5, for example, the soaking plate is made of a quartz plate or a sapphire plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat treatment apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a heat treatment apparatus according to the present invention, and FIG. 2 is an exploded perspective view showing a mounting table. Here, a film forming apparatus will be described as an example of the heat treatment apparatus. As shown in the figure, a film forming apparatus 10 as a heat treatment apparatus has a processing container 12 formed into a cylindrical shape by, for example, aluminum.
A large number of gas outlets 14 are provided on the ceiling of the processing vessel 12.
Is provided, so that, for example, a film forming gas can be introduced into the processing container 12 as a processing gas. Note that a diffusion plate may be provided in the shower head 16. On the side wall of the processing container 12, a carry-in / out port 20 is formed, and a gate valve 18 is provided in the carry-in / out port 20 so as to be openable and closable.

An exhaust port 22 connected to a vacuum pump or the like (not shown) is provided at the bottom of the processing container 12 so that the inside of the processing container 12 can be evacuated as necessary. In the processing container 12, a mounting table 26 is provided upright from a bottom portion of the processing container 12 via a support post 24 for mounting a semiconductor wafer W as an object to be processed. The mounting table 26 is entirely made of ceramics such as AlN, for example, and a heater 28 made of a resistor such as a molybdenum wire is embedded in the inside thereof in a predetermined pattern. A heater power supply 32 is connected to the heater 28 via a switch 30.
Electric power is supplied to the heater 28 as needed.

On the mounting table 26, a thin heat equalizing plate 34, which is a feature of the present invention, is installed. On the mounting table 26, a semiconductor wafer W to be processed is directly placed. The diameter of the heat equalizing plate 34 is set to be substantially the same as the diameter of the mounting table 26 below, and a guide ring 3 made of, for example, Al ₂ O ₃ or the like having an L-shaped cross section is provided on the peripheral edge of both.
6 is mounted to fix the heat equalizing plate 34 to the mounting table 26 side. The soaking plate 34 has a thickness of, for example, 0.5.
It is made of a disc-shaped quartz plate or sapphire plate of about 1.5 mm, and radiated heat is scattered to the surroundings by multiple reflection of radiant energy inside. The thickness of the soaking plate 34 is merely an example, and is not limited to the above value. Here, the front surface (upper surface) or the back surface (lower surface) of the heat equalizing plate 34 may be a flat smooth surface, but is preferably on at least one of the front surface or the back surface, and more preferably on both surfaces. Roughening treatment (blast treatment) is performed by a blasting device or the like so that minute irregularities are formed. This makes it possible to increase the reflectance of radiant energy from the inside of the temperature equalizing plate 34 to the upper wafer W and the lower mounting table 28, and to easily cause multiple reflection inside the temperature uniforming plate 34. Thus, it is possible to further improve the heat flicking effect.

Next, the operation of the embodiment constructed as described above will be described. First, the gate valve 18 provided on the side wall of the processing container 12 is opened, and an unprocessed semiconductor wafer W is loaded into the processing container 12 from the load lock chamber (not shown) via the loading / unloading port 20. It is placed in a state of being directly placed on the temperature equalizing plate 34 fixed integrally with the placing table 26 by the lifting / lowering operation (not shown). Next, the inside of the processing container 12 is closed, the power supplied to the heater 28 is increased, and the temperature of the mounting table 12 that has been preheated is raised to the process temperature and maintained. At the same time, a film forming gas whose flow rate is controlled as a processing gas is supplied from the shower head section 16 into the processing chamber 12, and the processing chamber 12 is evacuated from the exhaust port 22 to evacuate the processing chamber 12 through a predetermined process. While maintaining the pressure, a film forming process is performed.

Here, in the case of forming a SiN film as a film forming process, for example, dichlorosilane or N
H ₃ is used, and the process temperature at that time is, for example, 650 to 7
Within the range of 00 ° C., the process pressure is, for example, 0.2 to 0.3.
Each is set within the range of Torr. In such a film forming process, the heat generated from the heater 28 heats the mounting table 26, and this heat is transmitted to the wafer W through the heat equalizing plate 34 by heat conduction or as radiant energy. The wafer W is heated and maintained at a predetermined temperature.
The transfer of heat energy here is performed mainly by heat radiation rather than heat conduction. Here, as described above, the temperature of the surface of the mounting table 26 depends on the unevenness of pressure distribution and the heating when the mounting table 26 is formed by embedding the heater 28 in the ceramic material and performing hot press sintering. The distribution of the material constituting the heater 28 tends to be non-uniform due to non-uniform diffusion or the like.

As described above, if the wafer W is placed directly on the mounting table 26 in a state where the surface temperature of the mounting table 26 varies and is non-uniform, the non-uniformity of the temperature is directly reflected on the temperature distribution of the wafer W. This is not preferable in the film forming process. Therefore,
In the present invention, as described above, the thin temperature equalizing plate 34 is disposed on the upper surface of the mounting table 26, and the wafer W is placed directly thereon, so that the temperature of the upper surface of the mounting table 26 becomes uneven. The heat is transmitted to the wafer W in a state where the property is relaxed, and the in-plane uniform temperature of the wafer W can be maintained at a high level. Here, the operation of the thin soaking plate 34 will be specifically described.

FIG. 3 is an enlarged schematic view showing the direction of radiant energy at a certain point on the mounting table, and FIG. 4 is an enlarged view showing the state of propagation of radiant energy in a specific direction of the radiant energy in FIG. It is a schematic diagram. As shown in FIG. 3, from a certain point P on the surface of the mounting table 26, the radiant energy is diffused and radiated to the transparent soaking plate 34 in contact therewith so as to be distributed spherically. Focusing on the radiant energy in one direction among the radiant energies diffused in a spherical shape, the radiant energy repeats multiple reflections between the upper surface and the lower surface of the transparent soaking plate 34 as shown in FIG. However, the heat energy at the point P acts to be dispersed and scattered around this point while reducing the heat energy at each reflection.

Here, a Si wafer is used as the semiconductor wafer W, a quartz glass plate is used as the soaking plate 34, and the mounting table 2
When AlN is used as 6, when the radiant energy propagating in the heat equalizing plate 34 is reflected at the boundary surface with the semiconductor wafer W, the reflectance becomes approximately 0.35, and the absorption toward the wafer W is performed. The rate is approximately 0.65. When the radiant energy propagating in the soaking plate 34 is reflected at the interface with the mounting table 26, the reflectance is approximately 0.2, and the absorptivity to the mounting table 26 is approximately 0.8. Become. The radiant energy is propagated in a direction away from the point P in the horizontal direction while being reflected in such an attenuated state. As described above, radiant energy is diffused in the plane direction from each point on the surface of the mounting table 26 as described above, and as a result,
Even if a temperature distribution is generated on the surface of the wafer W, this thermal energy is
For example, when the temperature is propagated to a portion where the temperature tends to be high, the temperature is scattered around and the temperature distribution is smoothed. As a result, the in-plane uniformity of the temperature of the wafer W can be kept high, and the heat treatment, for example, the in-plane uniformity of the film thickness can be increased.

In the above embodiment, both upper and lower surfaces of the heat equalizing plate 34 are made smooth, but the surfaces or both surfaces may be roughened by applying fine unevenness by sandblasting or the like. According to this, the reflectance of the upper and lower surfaces of the soaking plate 34 can be similarly increased. FIG. 5 shows the state at this time. Here, both the upper surface 34A and the lower surface 34B of the soaking plate 34 are subjected to a roughening process to form fine irregularities. By performing the surface roughening treatment on the surface of the soaking plate 34, the pseudo reflectance of the radiant energy propagating in the soaking plate 34 depends on the degree of the surface roughening. At the boundary of the lower surface of the mounting table 26, it rises to about 0.7 (the transmittance is about 0.3), and at the boundary of the upper surface of the mounting table 26, it rises to about 0.7 (the transmittance is about 0.3). ing. For this reason, the thermal energy can be scattered to a position farther in the horizontal direction than the point P on the upper surface of the mounting table 26 which is the source point of the radiant energy. It is possible to further improve the uniformity. The surface roughening process may be performed on only one of the upper and lower surfaces of the heat equalizing plate 34 instead of the upper and lower surfaces.

Further, in the above embodiment, when the surface of the soaking plate 34 is roughened, the surface is roughened in a uniform state. However, the present invention is not limited to this. The degree of surface roughening may have a distribution according to the temperature distribution on the surface of the mounting table 26. For example, the surface of the heat equalizing plate corresponding to the region where the temperature of the mounting table surface becomes high increases the degree of surface roughening to increase the reflectance of the radiant energy in that portion (the absorption rate is low), and The surface of the soaking plate corresponding to the region where the temperature of the mounting table surface becomes low has a small degree of surface roughening or is not subjected to surface roughening to reduce the reflectance of radiant energy at that portion ( (Absorption rate is large). 6 and 7 show such a state. FIG. 6 shows a temperature distribution when the mounting table 26 is heated to a predetermined process temperature, and FIG.
3 shows a soaking plate corresponding to the mounting table of FIG. FIG. 7 (A)
Shows a plan view of the soaking plate, and FIG. 7 (B) shows a cross-sectional view corresponding thereto. As shown in FIG.
When the temperature is raised to the process temperature, a temperature distribution occurs on this upper surface.

Here, it is assumed that the temperature of the area A surrounded by the dotted line at the center of the mounting table 26 tends to be slightly higher than the surrounding area. In this case, as shown in the temperature equalizing plate 34 in FIG. 7, the roughening treatment of the portion of the region B corresponding to the region A is made fine, and the pseudo reflectance with respect to the radiant energy in this portion is increased. I do. And
The extent of the surface roughening process in the region outside the region B is suppressed, and the pseudo reflectance for radiant energy in this region is made lower than the above. Thereby, the thermal energy in the region A where the temperature of the mounting table 26 tends to be higher can be more efficiently scattered and diffused to the outer periphery thereof, and the thermal energy in the region outside the region A can be diffused more efficiently. Since the degree of diffusion is suppressed, as a result, the in-plane uniformity of the temperature of the wafer W can be further improved due to the synergistic effect of the two.

Although the above embodiment has been described with reference to the SiN film forming process as an example, the present invention can be applied to film forming processes of other film types, and is not limited to the film forming process. Needless to say, the present invention can be applied to other heat treatments such as oxidation diffusion treatment and annealing treatment. For example, FIG. 8 shows an annealing reforming apparatus 4 using an ultraviolet lamp as a heat treatment apparatus according to the present invention.
0 shows a cross-sectional view when applied to FIG. This device 40
Is used to anneal and modify a film deposited on the surface of the wafer W, such as a TaOx film. A large opening 42 is provided in the ceiling portion of the processing container 12 and an O
A transmission window 44 made of, for example, quartz and sealed by a seal member 45 such as a ring is provided. An ultraviolet lamp 48 covered by a casing 46 is disposed above the wafer, and the ultraviolet light UV is applied to the wafer W on the soaking plate 34 fixed on the mounting table 26. In this case, the shower head section 16 does not impede the transmission of ultraviolet rays.
For example, to use a quartz annular shower head 16, for example, O ₃ as this from a process gas
(Ozone).

Also in this case, the soaking plate 3 is placed on the mounting table 26.
4, the in-plane uniformity of the temperature of the wafer W is maintained at a high level, and the in-plane uniformity of the annealing reforming process as the heat treatment can be improved. Since the wafer W is placed directly on the soaking plate 34, ozone does not enter the back surface of the wafer W, and the back surface of the wafer W is not oxidized. Further, in the present embodiment, a semiconductor wafer has been described as an example of an object to be processed, but the present invention is not limited to this.
Of course, the present invention can be applied to the case of processing a CD substrate, a glass substrate, and the like.

[0022]

As described above, according to the heat treatment apparatus of the present invention, the following excellent functions and effects can be exhibited. Since a radiant energy plate is provided on the upper surface of the mounting table and the radiant energy is reflected multiple times in this temperature equalizing plate, the object to be processed is heated in a state where the temperature distribution on the surface of the mounting table is relaxed. And the in-plane uniformity of the temperature can be improved. In addition, since the diffusion of thermal energy can be promoted by roughening the surface of the soaking plate, the in-plane uniformity of the temperature of the object to be processed can be further improved. Furthermore, by providing the surface roughening treatment of the soaking plate with a distribution corresponding to the surface temperature distribution of the mounting table, the in-plane uniformity of the temperature of the object to be processed can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a heat treatment apparatus according to the present invention.

FIG. 2 is an exploded perspective view showing a mounting table.

FIG. 3 is an enlarged schematic view showing a direction of radiant energy at a certain point on a mounting table.

FIG. 4 is an enlarged schematic diagram showing a state of propagation of radiant energy in a specific direction among radiant energies in FIG. 3;

FIG. 5 is an explanatory diagram for explaining a propagation state of radiant energy when both surfaces of a temperature equalizing plate are subjected to a roughening process.

FIG. 6 is a diagram showing a temperature distribution when the mounting table is heated to a predetermined process temperature.

FIG. 7 is a view showing a soaking plate corresponding to the mounting table of FIG. 6;

FIG. 8 is a sectional view when the present invention is applied to an annealing reforming apparatus using an ultraviolet lamp as a heat treatment apparatus.

FIG. 9 is a schematic configuration diagram showing a conventional general heat treatment apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Film-forming apparatus (heat processing apparatus) 12 Processing container 16 Shower head part 26 Mounting table 28 Heater 34 Temperature uniforming plate 36 Guide ring W Semiconductor wafer (workpiece)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K030 AA03 AA06 AA13 BA40 CA04 CA12 DA09 FA10 GA02 KA23 KA46 LA12 LA15 5F045 AA03 AB33 AD10 AE19 BB02 DP03 EB02 EF05 EK07 EK12 EM02 EM08 EM09

Claims (5)

[Claims] In a heat treatment apparatus, a mounting table for mounting an object to be processed is provided in a processing container, and a predetermined heat treatment is performed on the object to be processed. A heat treatment apparatus characterized in that a plate is installed. 2. The heat treatment apparatus according to claim 1, wherein the mounting table is formed by embedding a heater in ceramics. 3. The heat treatment apparatus according to claim 1, wherein at least one of the front surface and the back surface of the soaking plate is subjected to a surface roughening treatment. 4. The heat treatment apparatus according to claim 3, wherein the soaking plate has a distribution in the surface roughening treatment according to a temperature distribution on the surface of the mounting table. 5. The heat treatment apparatus according to claim 1, wherein the soaking plate is made of a quartz plate or a sapphire plate.