JPH1192940A - Device for forming material, such as semiconductor and superconducting material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form semiconductors, etc., which are uniform over the entire surface of a wafer with lessened generation of dust by supplying gas for film formation in nearly parallel with the wafer and supplying the gas which has high reactivity and does not form the film near the wafer through plural holes approximately from above the wafer. SOLUTION: The wafer 1 is arranged via a wafer supporting bace 2 into a reaction chamber 3. The wafer 1, the gas existing near the wafer and the walls, etc., of the reaction chamber 3 are heated and regulated nearly to an equal prescribed temp. by a heater 5. SiH4 is regulated in its concn. by H2 and is supplied as the gas for film formation into the reaction chamber 3 from its one side and the flow of the gas is formed in nearly parallel with the wafer 1 near the wafer via a vacuum discharge system 4. Further, PH4 having high activity for a dopant is supplied together with H2 from the holes of plural gas supply pipes 6 from above the wafer 1 to effect a uniform reaction. As a result, the polysilicon film or epitaxial silicon film uniformly doped with the P is efficiently formed on the wafer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for manufacturing a semiconductor or other material, in which a metal film, a metal silicide film, an oxide film, a nitride film, a polysilicon film, a high dielectric film or an epitaxial silicon film is formed on a wafer surface. A method of performing uniform processing over the entire surface of a wafer in a single-wafer CVD apparatus for processing wafers one by one or a pseudo-single-wafer CVD apparatus for simultaneously processing a small number of wafers such as two wafers. The present invention relates to a structure of an apparatus for realizing this, a method thereof, a wafer and a semiconductor using the apparatus.

[0002]

2. Description of the Related Art Oxidation and CV by supplying gas to a reaction chamber
Material manufacturing processes such as semiconductors such as D, epitaxial growth, and etching are usually performed on wafers, and it is required that the processes be uniform over the entire surface of the wafer.

[0003] As an example of a method for making the processing performed on a wafer uniform over the entire surface of the wafer, there is a gas supply means called a shower head. This is described in, for example,
As disclosed in Japanese Patent No. 164222, gas is supplied to a substantially entire surface of a wafer through a plurality of holes from a direction substantially perpendicular to the wafer. In this method, gas is supplied to the position of the supply port,
By changing the size, shape, and the like, the growth rate of a film formed by CVD can be made uniform.

[0004] As another example for uniformity over the entire surface of the wafer, there is a means for rotating the wafer. For example, Electronic Materials, March 1995, pp. 67-70.
As described above, the wafer placed on the support table is rotated together with the support table. This means that if the gas is flowed in one direction without rotating the wafer, the degree of processing of the wafer differs between upstream and downstream of the flow, but by rotating the wafer, the uniformity in the circumferential direction is improved. Things.

[0005]

When a gas for depositing a film is supplied to the reaction chamber through the shower head, there is a problem that holes in the shower head are clogged or particles are generated. In particular, this problem was remarkable when the temperature of the shower head was high. Therefore, it has been very difficult to use a shower head in an apparatus in which the entire reaction chamber is maintained at substantially the same temperature as the wafer. For the same reason, the above problem cannot be avoided even when two or more wafers are placed at substantially parallel positions at a time and the wafers are simultaneously processed. Further, the gas supply by the shower head has a disadvantage that the gas supply amount from each hole varies depending on the dimensional accuracy of the holes. This disadvantage was particularly noticeable when the showerhead was made of a brittle material such as quartz.

In addition, a semiconductor and other material processing apparatus that obtains uniformity by rotating a wafer also has a problem that a rotating mechanism of the wafer is indispensable and the structure becomes complicated. In addition, by rotating the wafer, uniformity in the circumferential direction can be improved, but there is a problem that the effect of improving uniformity in the radial direction is small.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus and a method for processing semiconductors and other materials in which the processing performed on the wafer is uniform over the entire surface of the wafer and that generates less dust.

[0008]

An object of the present invention is to provide a gas for depositing a film, for example, silane or disilane, which is supplied so that its flow is substantially parallel to a wafer, and which has high reactivity but has a high reactivity. In this case, a gas that does not form a film, or a gas that forms a film but the growth rate of the film is extremely low, such as diluted phosphine, can be solved by supplying the gas through a plurality of tubes from the vicinity of the wafer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Here, for the sake of explanation, hydrogen (H ₂ ), silane (S
A process of forming a phosphorus-doped polysilicon film or a phosphorus-doped epitaxial silicon film by using a source gas of iH ₄ ) and phosphine (PH ₃ ) is taken as an example. Needless to say, the same effect can be obtained.

FIG. 1 is a side view of an embodiment of the present invention. The wafer 1 is supported by a wafer support 2 and is placed in a reaction chamber 3. The pressure in the reaction chamber 3 is kept constant by a vacuum evacuation system 4 composed of a vacuum gauge, a valve, a vacuum pump and the like. The wafer 1 is heated by the heating device 5 in the reaction chamber 3 and is maintained at a predetermined temperature after a certain period of time. When the temperature of the wafer is maintained at a predetermined temperature, silane and hydrogen are supplied from the left of the reaction chamber 3 in FIG. 1, and phosphine is supplied from above the wafer through the gas supply pipe 6. Here, for convenience, the x-axis is defined from left to right in FIG. 1, the y-axis is defined in the depth direction of the drawing, and the z-axis is defined in a direction perpendicular to the surface of the wafer 1 in FIG. The supplied silane forms a silicon film on the wafer 1. Phosphorus in the phosphine is taken into the silicon film formed on the wafer 1 at the same time.

The reason that phosphine is supplied from the vicinity of the wafer separately from silane is that the supplied phosphine is more attenuated than silane and is consumed in a large amount before reaching the wafer. . Unconsumed phosphine is also heavily consumed upstream of the wafer,
The amount of phosphorus contained in the silicon film grown upstream of the wafer is large and small downstream. To solve this, phosphine must be supplied from the vicinity of the wafer separately from silane. In addition, since the phosphine is greatly attenuated, the phosphine must be uniformly supplied from a plurality of locations.

One example of means for realizing this is shown in FIG.
Is to supply phosphine and hydrogen from the gas supply pipe 6 provided above the wafer. One specific example of the gas supply pipe 6 is the gas supply pipe 6 in FIG. FIG.
In the examples of (a), (b), and (c), a plurality of gas supply pipes 6 having substantially the same inner diameter, substantially the same length, and having the same cross-sectional area at the end of the pipe are prepared. The positions of the tips are substantially the same in x and are arranged at substantially equal intervals in the y direction, and the plurality of gas supply pipes 6 are set at a temperature higher than the temperature of the ejection holes located at the approximate ends of the respective gas supply pipes 6b. It is shown connected to a gas reservoir 7 having a conductance sufficiently higher than the conductance of the gas supply pipe 6 at a sufficiently low position.

Further, by using a plurality of such sets, the ejection holes located at the substantially end of the gas supply pipe 6 are arranged at substantially equal intervals in the x direction. These gas reservoirs 7 may be installed inside or outside the reaction chamber 2. When phosphine and its diluent gas, hydrogen, are supplied to the reaction chamber 3 using such a gas supply system, the wafer 1
It is possible to make the concentration of phosphorus uniform over the entire surface of the substrate.

When the gas supply pipe 6 is configured as described above,
The amount of gas supplied from each hole is determined by each gas supply pipe 6.
Therefore, even if the cross-sectional area of each hole is slightly shifted, the conductance of the entire supply pipe is hardly affected if the conductance of the pipe is small. Therefore, high precision is not required for processing the supply holes. as a result,
Even if a brittle material such as quartz is used for the gas supply pipe 6, uniform gas supply can be realized. Here, if a metal is used for the gas supply pipe 6, the metal may be mixed into the wafer or the film to be grown. Since metal contamination can significantly reduce the yield of devices such as semiconductors, quartz or ceramic is preferable as the material of the gas supply pipe 6.

Phosphine is added to reduce the resistance of silicon by adding phosphorus to silicon, and the amount of phosphorus contained in the formed film is much smaller than that of silicon. Therefore, the amount of phosphine supplied as a gas is also significantly smaller than that of silane, and phosphine is usually diluted with hydrogen or the like and supplied to the reaction chamber. Therefore, even if the reactivity is high, the gas supply holes are not blocked by the phosphorus formed by the phosphine. However, if silane is to be supplied from the gas supply pipe 6, silane is originally added to deposit a silicon film,
There is a possibility that the hole of the gas supply pipe 6 may be closed, the cross-sectional area of the hole may not be completely closed, but the cross-sectional area of the hole may be reduced, or the silicon film that has been deposited may be peeled off, causing particles to be generated. . Therefore, in the present invention, silane is not supplied from the gas supply pipe 6.

As an example of a device for making the thickness of silicon grown on a wafer uniform, a plurality of gas supply pipes 6 are connected by welding or the like, and a substantially flat plate is formed on the wafer. There is a method of making the surface area per space constant as if it were placed. In this method, the gas supply pipe 6 needs to be welded in all regions at least in a region located immediately above the wafer. However, this welding is sufficient if the ceiling is present at a certain height when viewed from the wafer, so that it is not always necessary to perform dense welding to the inside. Further, this welding is unnecessary in a region that is separated from the wafer to some extent in the x direction and the y direction.

On the other hand, the wafer support 2 is configured as follows. In the space near the wafer, a wafer support 2 is provided around the wafer 1 so that the ratio of the surface area to the space does not change so much.
Are made substantially the same. Wafer 1
The hollowed portion of the wafer support 2 has a shape close to the wafer 1 so that only a part of the wafer support 2 is not particularly separated when viewed from above. The outer shape of the wafer support 2 is substantially rectangular.

The reason that the growth rate of silicon on a wafer becomes uniform due to the presence of a surface at a certain height when viewed from the wafer is as follows. That is, monosilane (SiH ₄ ) as a raw material is converted into silylene (Si
H ₂ ). The generated silylene very easily adheres to the surface, and when it is generated, it is consumed on a surface (such as a wafer or an inner wall of a reaction chamber) near the position. The consumed silylene forms a silicon film. Therefore, the growth rate of silicon depends on how much surface area of silylene produced per unit time is consumed. Therefore, in the space near the wafer, the growth rate of silicon grown on the wafer can be kept almost constant by making the ratio of the surface area included per space considered substantially constant.

For the same reason, the following device is also effective. For example, as shown in FIG. 3, a plurality of substantially parallel slits are provided in the plate 9 and the gas supply pipes 6 are mounted on the slits so that the position of the gas supply pipes 6 is hardly shifted.
In this method, it is also possible to mount two gas supply pipes 6 from both sides of one slit. At this time, the two gas supply pipes 6 placed in one slit are connected to another gas reservoir.

According to the present invention, the distance from the wafer to the nearest plate 9 or gas supply pipe 6 becomes substantially uniform over the entire surface of the wafer, so that the growth rate of silicon on the wafer becomes uniform. At this time, the gas ejection holes are provided near the tip of the gas supply pipe 6, and the gas ejection direction is set to be approximately perpendicular to the wafer. According to the present invention, there is an advantage that welding or the like is unnecessary and the structure can be easily formed, and two gas supply pipes 6 can be mounted on one slit. At this time, each gas supply pipe 6 is connected to another gas reservoir. Here, for example, quartz is suitable as the material of the plate 9. This is because it has sufficient strength at a process temperature of about 500 ° C. to 1100 ° C., has few impurities, and is hardly corroded by etching with hydrogen chloride or the like.

3A, 3B and 3C,
There is also a method in which a hole is provided in the plate 9 by aligning the position of the gas ejection hole of the gas supply tube 6 with the hole provided in the plate 9 without providing a slit in the length direction of the gas supply tube 6. At this time, if the plate 9 is processed into a corrugated shape and the gas supply pipe 6 is placed in the concave portion of the wave, the position of the plate 9 and the gas supply pipe 6 are less likely to shift. Furthermore, the direction of the gas ejected from the gas ejection holes provided near the tip of the gas supply pipe 6b should be substantially perpendicular to the wafer, and its position should match the position of the holes provided in the plate 9. For example, the same effect as the invention of FIG. 3 can be expected without adding a special device. According to the present invention as well, welding or the like is not required, and the structure can be easily achieved.

FIG. 4 shows an approximately rectangular flow path formed by cutting the inside of the plate 9 into a substantially rectangular shape or forming a flow path by laminating the plates, etc., directly to the gas reservoir 7. The gas ejection holes are provided on the surface facing the wafer among the surfaces. Here also, the height of the flow channel may be reduced so that the conductance of the substantially rectangular flow channel is smaller than the conductance of the hole so that the amount of phosphine jetted from each jet port is constant. Further, in FIG. 4, by providing a partition 10 near the center of the plate 9, it is possible to provide gas ejection holes in at least two places in the main flow direction without complicating the apparatus. By adjusting the length of the phosphine flow path supplied to the gas reservoir 7 in the reaction chamber 2 where the temperature is high, the amount of phosphine spouted from the gas spouting hole can be adjusted. In FIG. 4, two phosphine flow control devices 8 are provided, but it is also possible to substitute one phosphine flow control device 8 for supplying phosphine to two flow paths by the above concentration control. .

FIG. 5 shows a configuration in which the phosphine supply device shown in FIG. 4 is a part of the reaction chamber 3 into which the wafer 1 is inserted. This has the advantage that the size of the device can be reduced. In this figure, it can be seen that the automatic transfer of the wafer by the wafer transfer robot can be easily realized by opening and closing the gate valve. At this time, the silane supply port is located below the reaction chamber 2 so as not to hinder automatic transfer by the wafer transfer robot.

Further, as a modification of the invention shown in FIG.
May have a double structure. That is, the flow path for supplying phosphine is provided outside the region where the wafer 1 is inserted and the silane is supplied. The outer space and the inner space are connected by a gas ejection hole provided in the vicinity of the wafer 1, and the phosphine supplied to the outer space is finally placed on the wafer 1 by the small hole. It will also be supplied to the inner space.

In these inventions, the respective gases are supplied together with the flow rate control device in FIG. 4 by controlling the pressure so that the pressure difference between the inner and outer spaces or the upper and lower spaces does not become too large. There is a need to. The reason for not increasing the pressure difference is to prevent the structure from being destroyed by the pressure difference. Further, in order for phosphine to reliably reach the vicinity of the wafer 1, the pressure at the gas ejection hole position on the phosphine supply side needs to be higher than the pressure at the gas ejection hole position on the silane supply side. Must be controlled.

The plate 9 as shown in FIG. 4, FIG. 5, FIG.
Can be placed on a support protrusion provided on the side wall of the reaction chamber 3 or its position can be set by a plurality of columns installed on the bottom surface of the reaction chamber 3, so that the structure of the apparatus is not largely changed.

FIG. 6 shows an embodiment in which two wafers are processed simultaneously. The basic configuration is shown in Figs.
As shown in (1), two of them can be processed simultaneously by combining them. In FIG. 6, a gate valve is provided on the upstream side (left side in the figure) of the reaction chamber 3 so that automatic opening and closing of the wafer 1 by the wafer transfer robot existing in the adjacent wafer transfer robot chamber is facilitated by opening and closing the gate valve. It is devised. Further, at this time, the supply of silane is supplied from the upper side so as not to hinder the transfer of the wafer 1, and the supply of phosphine is supplied in a direction perpendicular to the sheet of the drawing. In addition, a configuration in which three or more wafers are simultaneously processed with substantially the same contrivance is also possible.

Although the gas reservoir 7 is placed inside the reaction chamber 3 in the present invention, it may be placed outside the reaction chamber 3.

As a material of the gas supply pipe 6, the plate 9, or the wafer support, for example, quartz is suitable. The reason is that it has sufficient strength at a process temperature of about 500 ° C. to 1100 ° C., has few impurities, and is hardly corroded by etching by hydrogen chloride or the like.

In the present invention, for the sake of simplicity, a diagram is shown in which phosphine is supplied only from a position different from silane, but SiH ₄ + H ₂ in the figure is SiH ₄ + PH ₃ + H _2.
May be replaced by That is, the phosphine may be supplied from the same position as the silane, and may be supplied according to the above invention. Further, in the present invention, hydrogen is used to adjust the raw material concentration of silane and the raw material concentration of phosphine,
From the viewpoint of homogenizing phosphorus taken into the silicon film, an equivalent effect can be expected even if a low-activity gas such as nitrogen or helium is used instead of hydrogen.

Further, it goes without saying that the above invention is also effective when phosphorus trichloride (PCl ₃ ) or diborane (B ₂ H ₆ ) is used instead of phosphine (PH ₃ ) as a doping gas.

[0032]

According to the present invention, the concentration of phosphorus contained in a silicon film or the like can be made uniform. Therefore, the number of semiconductor chips that can be obtained from one wafer is increased, and the yield is reduced. Further, the present invention is effective for a larger wafer in the future. Further, according to the present invention, a plurality of wafers can be simultaneously and uniformly processed,
There is also an effect of reducing the time for processing one wafer.

[Brief description of the drawings]

FIG. 1 is a diagram showing a material forming apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram showing a material forming apparatus using a plurality of gas supply pipes according to one embodiment of the present invention.

FIG. 3 is a view showing a plurality of gas supply pipes on a slit plate according to an embodiment of the present invention.

FIG. 4 is a view showing a flow path obtained by hollowing out a plate according to one embodiment of the present invention.

FIG. 5 is a diagram showing a reaction chamber according to one embodiment of the present invention.

FIG. 6 is a view showing a pattern in which two wafers of one embodiment of the present invention are inserted into one reaction chamber.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer, 2 ... Wafer support, 3 ... Reaction chamber, 4 ... Vacuum exhaust system, 5 ... Heating device, 6 ... Gas supply pipe, 7 ... Gas reservoir, 8 ... Flow control device, 9 ... Plate, 10 ... Partition .

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // H01L 21/31 H01L 21/31 B (72) Inventor Yoshihiko Sakurai 5-2-1, Josuihoncho, Kodaira-shi, Tokyo Hitachi, Ltd.Semiconductor Division (72) Inventor Hironori Inoue 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. No. 1 in the Hitachi Research Laboratory, Hitachi, Ltd.

Claims (1)

[Claims] An apparatus for forming a semiconductor or other material for processing a wafer by supplying a gas to a reaction chamber, wherein a gas is supplied to the reaction chamber, and the temperature of the wafer is in the vicinity of the wafer and the gas is present in the vicinity thereof. An apparatus having a function capable of controlling the temperature so that the temperature of the gas and the wall of the reaction chamber are approximately equal. In the vicinity of the wafer, the main flow of the gas A is substantially parallel to the wafer, and is inert. An apparatus for forming a material such as a semiconductor or a superconducting material, wherein a gas B containing a non-component is supplied through a plurality of holes from above a wafer.