JPH0347531A - Fluid dispersing apparatus and treatment apparatus using the same - Google Patents

Abstract

PURPOSE:To make the concentration distribution of a fluid almost uniform and disperse the fluid by installing a porous body midway in a fluid supplying route and passing the fluid through the cross section of the porous body. CONSTITUTION:A porous body 14 is put midway in a fluid supplying route 16 and a fluid is passed through the cross section 14 of the porous body so that the concentration distribution of the fluid is made almost uniform and disperse the fluid. For example, an injector 16 is prepared by unitedly sintering a porous highly pure alumina part 14 and a convertional highly pure alumina part 15. When a reaction gas at high pressure is supplied to the injector 16, the gas is sprayed outside through infinitely thin capillary tubes and thus the internal pressure of each pore of an injector can be set to be extremely close to that at the tip part and the sprayed amount of the reaction gas can be made uniform independently of the location. Moreover, the mechanical strength of the injector is higher as compared with that of injector made of quartz and the injector has excellent temperature characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a fluid diffusion device and a processing apparatus for processing an object to be processed using a reactive gas.

(Prior Art) In the semiconductor industry, it is an important technique to uniformly add impurity atoms to a semiconductor substrate, either directly or indirectly.

In addition, it is a technology in which, for example, a silicon compound such as silicon dioxide, or a polycrystalline or single crystal layer is formed on a semiconductor substrate, and impurity atoms are uniformly added to the silicon or silicon compound, and its reproducibility is important. be. As semiconductor devices become more sophisticated, for example, the higher the degree of integration in semiconductor integrated circuit devices, the more the amount of impurity atoms added to the semiconductor crystal, the various vapor phase growth layers on the semiconductor substrate, and the vapor + U growth layer. It is necessary to precisely control the number of impurity atoms added to the material.

For example, in the case of forming a silicon dioxide layer, a horizontal heat treatment furnace was conventionally used, but a method to make the concentration distribution of the reaction gas more uniform in the reaction region (the region containing the silicon substrate) This was extremely difficult due to structural reasons. In order to overcome this difficulty, in recent years the entire system has been made into a vertical structure.

FIG. 8 shows a conventional vertical furnace, in which the entire system is covered with a heating furnace 1, inside which is an outer tube 2. An inner tube 3 is provided.

A quartz boat 4 can be placed in the soaking area of the inner tube 3, and a large number of silicon substrates 5 are mounted on this boat 4. In order to introduce an inert gas as a carrier gas that regulates the flow rate of the reaction vessel into the inner tube 3, inert gas introduction pipes 6a and 6b are provided so that the inert gas can be introduced from the upper end of the inner tube 3. There is. On the other hand, reaction gas introduction pipes are usually provided corresponding to the type of reaction gas to be introduced, and in the case of vapor phase growth of a silicon dioxide layer, a silicon compound injector 7 and an oxygen gas injector 8 (injector 8 in FIG. 8) are used. is located behind the injector 7) and extends along the longitudinal axis of the inner tube 3. As shown in FIGS. 9(A) and 9(B), this injector 7.8 has a large number of holes 9 bored at predetermined intervals along its longitudinal axis, and these holes 9 are connected to the quartz boat 4. The injector 7.8 is disposed within the inner tube 3 so as to be set at a position facing the plurality of silicon substrates 5 mounted on the inner tube 3. As an exhaust system for the reaction vessel, an exhaust port 10 connected to the lower end side of the inner tube 3 is provided, and a large number of holes or slits 11 are provided on the wall surface of the inner tube 3 facing the injector 7.8.
is arranged so that the gas released to the outer tube 2 side through the slit 11 can be exhausted through the exhaust port 12.

Usually, the vapor phase growth of a silicon dioxide layer is carried out at normal pressure, but in order to further improve the uniformity of the film thickness, in order to increase the mean free path of the reaction gas,
The exhaust ports 10.12 are directly connected to the vacuum system. Furthermore, although the entire system is symmetrical in cylindrical coordinates with the boat 4 as the center, since the flow of the reaction gas is parallel to the surface of the silicon substrate 5, the entire boat 4 can be freely rotated by the rotating shaft 13 in order to ensure more uniformity. The rotational speed allows rotation during vapor phase growth.

(Problem to be solved by the invention) In recent years, the speed of technological innovation in semiconductor devices such as dynamic RAM, LM, 4M, and 16M is accelerating, and design standard values are entering the submicron range. Not only that, but we also adopted multi-layered vapor phase growth layers that included single-crystal silicon, and eventually hit a wall in device mounting technology.
It is believed that technological innovation will progress towards three-dimensional structures.

What can be considered here is precise control of the vapor phase growth layer, precise control of the number of impurity atoms not only in silicon but also in each vapor phase growth layer, and control of the chemical and physical properties of each vapor phase growth layer. be. For this purpose, it is necessary to make the reaction gas concentration distribution in the reaction region more uniform. In the above-mentioned apparatus, in the injector 7.8 shown in FIGS. 9(A) and 9(B), a plurality of holes 9 are formed N, N2, . ...N
, , the ejection flow velocity V1゜v2 of the silicon compound gas ejected from the first hole to the Nth hole, respectively.
．． ... It is desirable that all V are equal. For this purpose, the pressure P1 near the first hole to the pressure Pn near the Nth hole must all be equal, assuming a simple model in which the viscosity is very small.

However, it is almost impossible to satisfy the above conditions in a thin tube as long as 1 m and considering the temperature change of the reaction gas at a considerably high temperature.

Furthermore, the size of the hole 9 of the injector 7.8.

Density etc. are generally designed based on empirical rules depending on the type of reaction gas, etc., and there is also the hassle of having to replace the injector every time the type of reaction gas to be introduced changes.

Furthermore, in the thin tube of the injector 7.8 as described above,
When a large number of holes 9 are drilled, especially in the case of a heat treatment furnace, deformation occurs due to high temperature use, and the set values differ from those designed based on empirical rules, resulting in poor process reproducibility. There were also problems.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fluid diffusion device that diffuses a fluid by making the concentration distribution of the fluid substantially uniform, has strong mechanical strength, and has little thermal deformation. An object of the present invention is to provide a processing apparatus that can precisely control vapor phase growth and the like by using a fluid diffusion device as a diffusion supply section for a reaction gas.

[Structure of the Invention] (Means for Solving the Problems) The first invention provides a porous body in the middle of a fluid supply path, and allows the fluid to pass through the porous diffusion plate, thereby reducing the fluid concentration. It is characterized by making the distribution substantially uniform and diffusing the fluid.

A second invention provides a processing apparatus for processing the object to be processed by supplying a reaction gas into the processing container in which the object to be processed is arranged through an injector extending into the processing container, the injector It is characterized in that it is constructed of a hollow cylindrical porous body with one end sealed.

A third aspect of the present invention is a processing apparatus for processing the object by supplying a reactive gas from one end of the processing container into the processing container in which the object to be processed is disposed, wherein the reaction gas is supplied to the object to be processed. The feature is that a porous diffusion plate is disposed on the upstream side before reaching the target.

(for production) The porous body in the present invention refers to a porous body that is artificially processed.

its own nature, not something with formed pores;
This refers to a material that originally has a large number of holes in its internal structure randomly due to the manufacturing process. In this kind of porous material,
The shape and size of the holes may differ, but when comparing them for each unit area, the open area ratio per unit area is almost equal due to the large number of holes and the randomness of the arrangement. It is considered to be a thing. Therefore, by passing the fluid through the folded surface of this porous material, it becomes possible to make the fluid concentration distribution substantially uniform and to diffuse the fluid.

In addition, porous materials have a large number of micropores due to their own characteristics, so compared to conventional materials with artificially formed pores, their mechanical strength is stronger, and the selection of materials is also important. This makes it possible to sufficiently suppress thermal deformation.

By using such a fluid diffusion device as a reaction gas supply and diffusion means in general processing equipment, it becomes possible to make the concentration distribution of the reaction gas uniform within the reaction region, allowing precise control of vapor phase growth, etc. becomes.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

First, regarding an example of a fluid diffusion device, FIG. 1(A),
This will be explained with reference to (B). In FIG. 1(A), an injector 16 is formed by integrally sintering a porous high-purity alumina part 14 and a normal high-purity alumina part 15.

By supplying high-pressure reaction gas to this injector 16, it is ejected to the outside through a very small, nearly infinite capillary, so the internal pressure of the injector hole is
It can be set to very close pressures, including at the tip, and the amount of reaction gas ejected can be made uniform regardless of location. It also has greater mechanical strength and superior temperature characteristics compared to quartz.

In FIG. 1(B), a porous ceramic plate 20 is disposed in the middle of the fluid supply path 17, and in this case as well, uniform diffusion can be achieved by the same effect.

Note that the shape of the porous body may be any shape, and not only can it be a large spherical shape, but it is also possible to locally sinter porous ceramics, and it is possible to use any reaction gas or impurity-added gas in a wide range. , on the contrary, it is very suitable for local supply.

Next, an example applied to a processing device will be described.

FIG. 2 is an explanatory diagram of a phosphorus pre-diffusion furnace. This diffusion furnace was equipped with a heating furnace 18 covering the entire system, a quartz container 19 serving as a reaction container, and a porous ceramic flat plate 20 above the container. This porous ceramic flat plate 20 is made by sintering high purity quartz powder with a particle size distribution of 5 to 10 μm into a flat plate with a thickness of 5 mm, and is integrally processed with the quartz container 19.

In the center of this quartz container 19, a quartz boat 22 was placed on a rotating shaft 21, and a plurality of silicon substrates 23 were mounted. Nitrogen, oxygen, and phosphorous oxychloride are introduced into the pressurized vessel 25 through the gas inlets 24, 24' and enter the reaction vessel 19 as a constant velocity fluid through the porous ceramic plate 20.

First, the heating furnace 18 is set to a temperature of 700°C, and the reaction vessel 19
After replacing the interior with nitrogen gas and mounting 100 silicon substrates 23 on the quartz boat 22, the boat is inserted into the container. Subsequently, the temperature is reset to 900° C., and when the set temperature is reached, oxygen gas is flowed at 0.511 t/+in for 5 minutes. Next, further po
c! , at 120 mg/ln, and perform pre-diffusion for 20 minutes. After completion of diffusion, the introduction of oxygen gas and POCI into the reaction vessel is stopped, and the heating furnace is cooled at a rate of 5°C/*in. When the temperature reaches 500°C, the boat is removed from the reaction vessel and the inert gas is removed. Natural cooling is performed in the preliminary container until the temperature reaches 100° C. or lower, and then the silicon substrate is taken out from the boat, and the preliminary diffusion of phosphorus atoms is completed. Figure 3 shows the results of repeating the diffusion 10 times under the same conditions. On the X axis, the topmost silicon substrate on the boat was designated as No. 1, and the measurement values for every 10th substrate were shown, and the bottom silicon substrate, that is, the 100th sheet was designated as No. 100. The y-axis is layer resistance. As for how to display resistance values in the diagram, the 0 mark is the average value within one silicon substrate, and the spread of layer resistance values shown by bars above and below the 0 mark is the maximum and minimum values within one silicon substrate.

Further, the upper part of the figure shows the average value of the layer resistance values of each silicon substrate normalized by 1, and the vertical spread in the figure shows the distribution of layer resistance values within one silicon substrate in %.

FIG. 4 shows the reproducibility of individual diffusion, and shows the average value of each silicon substrate for 100 sheets in the lot. Another diffusion parameter, the P-n junction depth, has an absolute value of 0.
．． Since it is close to 1 am, it is omitted for reasons such as JPJ constant accuracy.

From this result, compared to the conventional vertical heating device, the layer resistance distribution within a single silicon substrate is ±4%, which is not a significant improvement, but the layer resistance distribution within the loft is ±2%, and the reproducibility is ±2. %, a remarkable improvement.

FIG. 5 is an explanatory diagram of a furnace for low-pressure vapor phase growth of a silicon dioxide layer. The differences from the conventional example shown in FIG. 8 are as follows. First, a plurality of gas inlets 26 using porous high-purity alumina tubes are provided.

The silicon dioxide layer is formed using 5iH2C12, and if the impurity atoms are simultaneously added to the silicon dioxide layer, for example, when considering the addition of phosphorus, The gas inlet 26 is 5i
Two pieces of H2Cr2 and poc B are required.

The reaction vessel 27 has a gas inlet 28 made of a porous ceramic flat plate.
and an exhaust port 29 having a plurality of holes or slits.

First, when forming an additive-free silicon dioxide layer, first, the inside of the reaction vessel 27 is replaced with an inert gas through the gas inlet 28 of the porous ceramic flat plate, and a plurality of silicon substrates 31 mounted on a quartz boat 30 are placed in the reaction vessel. Insert into 27. The temperature of the reaction vessel 27 is set in advance to 500°C. quartz boat 3
0 at the center of the reaction vessel 27, open the gas exhaust port 29.29
' is connected to the vacuum system through
．． Exhaust to 0.003 Torr. At this time, reaction vessel 27
311 t/ml of nitrogen gas is introduced from the gas inlet 28, 28', and the inside of the container 27 is heated to
Make it r. Subsequently, the temperature of the reaction vessel 27 was raised to 600°C at a rate of 10°C per minute, and 1.51 it/w of oxygen gas was added.
In from the gas inlet 28, 5iH2C12 gas 0.0
811 t/m1n was introduced from the inlet 26, and vapor phase growth was performed for 30 minutes. Approximately 300 vapor phase growth layers are formed on the silicon substrate 31.

On the other hand, when adding phosphorus atoms uniformly to this silicon dioxide layer, poc! , gas 120 m
By introducing phosphorus atoms into the reaction vessel 27 at a ratio of g/win, phosphorus atoms can be uniformly added to the silicon dioxide layer grown in a vapor phase.

As a result, measured values of the thickness of the vapor-phase grown layer and its distribution values are shown in FIG. Since there is no simple and accurate method for measuring the concentration of phosphorus atoms in silicon dioxide, the layer resistance of the diffusion layer is An indirect evaluation was conducted by The results are shown in Figure 7.

From this result, compared to the case of introducing various substrates through the conventional gas inlet and performing vapor phase growth, there is no significant improvement in the value within the silicon substrate, but the thickness distribution within the lot and the process There is a significant improvement in reproducibility. Furthermore, although it is an indirect method, significant improvements have been observed in the uniformity and reproducibility of the amount of phosphorus added.

Regarding the vapor phase growth of boron, phosphorus, and glass, for example, B
By adding an inlet for a boron compound gas such as Cl3, the process can be carried out using exactly the same apparatus as in the above embodiment, and a highly precise vapor phase growth layer can be obtained.

Furthermore, regarding the formation of polycrystalline silicon layers, single crystal silicon layers, TEOS, and HTO oxide film layers, which are widely applied in the semiconductor industry, the addition of impurity atoms thereto, and the vapor phase growth of silicon nitride layers, etc., depending on the gas used. By adding a corresponding gas inlet, a precisely controlled vapor phase growth layer can be easily obtained.

[Effects of the Invention] As explained above, according to the fluid diffusion device of the present invention,
By passing the fluid to be supplied through the cross section of the porous body, the fluid concentration distribution can be made almost uniform and the fluid can be diffused and supplied. Moreover, compared to the conventional hole-drilled one,
The mechanical strength is extremely high, and by selecting the material, it is possible to provide a material with little thermal deformation.

According to the processing apparatus of the present invention that uses this fluid diffusion device as a diffusion supply section of the reaction gas, the concentration distribution of the reaction gas can be made almost uniform and the concentration distribution can be diffused and supplied, making it possible to precisely control vapor phase growth, etc. Become.

[Brief explanation of drawings]

Figures 1 (A) and (B) are schematic explanatory diagrams showing an embodiment in which the fluid diffusion device of the present invention is applied to an injector and a diffusion plate. 3 is a characteristic diagram showing the layer resistance value and the distribution rate of the layer resistance value within the silicon substrate of the silicon substrate processed by the pre-diffusion furnace of FIG. 2, and FIG. is a characteristic diagram showing the reproducibility in the preliminary diffusion furnace shown in FIG. 2, FIG. The figure shows the fifth
Figure 7 is a characteristic diagram showing the measured values and distribution values of the thickness of the vapor-phase growth layer obtained in the reduced-pressure vapor-phase growth reactor shown in Fig. 5. Figure 8 is a schematic cross-sectional view of a conventional vertical heat treatment furnace, and Figure 9 (
A) and (B) are schematic explanatory diagrams for explaining a conventional injector used in the heat treatment furnace of FIG. 8. 14... Porous high purity alumina part, 16... Injector 20... Porous ceramic plate, 26... Porous high purity alumina tube, 28... Porous ceramic flat plate.

Claims (3)

[Claims] (1) A fluid characterized in that a porous body is disposed in the middle of the fluid supply path, and the fluid is passed through the cross section of the porous body, thereby making the fluid concentration distribution almost uniform and diffusing the fluid. Diffusion device. (2) In a processing apparatus that processes the object to be processed by supplying a reaction gas into the processing container in which the object to be processed is arranged via an injector extending into the processing container, the injector is connected to one end of the processing device. 1. A processing device comprising a hollow cylindrical porous body that is sealed. (3) In a processing apparatus that processes the object by supplying a reaction gas from one end of the processing container into the processing container in which the object to be processed is disposed, the reaction gas is supplied to the object in the processing container. A processing device characterized in that a porous diffusion plate is disposed on an upstream side before reaching a processing body.