JP3076268B2 - Low pressure vapor phase growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing process, and more particularly to a reduced pressure vapor phase growth apparatus for vapor phase growing a film on a semiconductor substrate (wafer) according to a source gas.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of semiconductors, there have been many film forming steps such as electrode formation and film formation using a mask, and a reduced-pressure vapor deposition apparatus has been used. FIG. 2 is a cross-sectional view of a conventional vertical reduced pressure vapor deposition apparatus.

[0003] The vertical type reduced pressure vapor deposition apparatus shown in FIG .
A heater 2 for keeping the inside of the furnace core tube 1 at a desired temperature;
A boat 4 on which the wafer 3 is mounted, a pump 5 for depressurizing the inside of the furnace core tube 1 and exhausting the reaction gas, a hatch 6 for sealing the furnace core tube 1, and a raw material gas inside the furnace core tube 1. And an inner inner tube 9 having a double tube structure in which the introduced raw material gas is divided into two and a part of the gas flows into a reaction section near the exhaust side. . The outer inner tube 9 is formed longer than the inner inner tube 10.

A desired film formation on a wafer in a conventional vertical type reduced pressure vapor phase epitaxy apparatus is performed as follows. First, the boat 4 on which the wafer 3 is mounted is inserted into the furnace core tube 1 kept at a desired temperature by the heater 2, the furnace core tube 1 is sealed by the hatch 6, and the inside of the furnace core tube 1 is After reducing the pressure to a desired pressure, the raw material gas was supplied from the introduction pipe 7, and passed through the gap between the outer inner pipe 9 and the inner inner pipe 10 on the wafer 3 located on the exhaust side where the gas concentration was reduced. A film is formed by introducing a relatively high-concentration source gas. Unreacted raw material gas is exhausted by the pump 5 and discharged to the outside of the furnace core tube 1.

[0005]

[0006]

[0007]

[0008]

However, in the apparatus shown in FIG. 2, the inner pipe is not a double pipe but only the outer inner pipe 9 from the portion where the inner inner pipe 10 is cut off . There is a tendency that the pressure increases and the internal pressure of the furnace core tube 1 decreases. For this reason, there is a problem that the partial pressure of the raw material gas at the portion where the inner inner pipe 10 is cut off decreases, and the film thickness or the impurity concentration decreases.

According to the present invention, the film thickness, impurity concentration, or film quality structure formed on wafers in the same batch is made uniform,
The purpose is to reduce manufacturing variations in products.

[0010]

According to the present invention, a boat on which wafers are mounted is loaded into a furnace core tube, and an inner tube having a double tube structure surrounding the boat is installed between the boat and the furnace core tube. Depressurize the inside of the core tube and transfer the reaction gas to the inner and outer tubes of the double tube.
In a reduced pressure vapor phase epitaxy apparatus for growing a film on a wafer by introducing a film between the inner tube and the inner side of the inner tube, the outer inner tube of the double tube is extended, and the extended portion is narrowed down to a tapered shape. , And the inner tube has a double-tube structure at one end and a single-tube structure at the other end.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a vertical type reduced pressure vapor phase epitaxy apparatus showing an embodiment of the present invention.
The description will be made by taking -situP-doped Si as an example.

A furnace core tube 1 serving as a reaction tube, a heater 2 for maintaining the inside of the furnace core tube 1 at a desired temperature (for example, 500 to 550 ° C.), a boat 4 on which a wafer 3 is mounted, and a furnace core tube 1 A pump 5 for evacuating the gas to a reduced pressure state, for example, 0.5 to 5 Torr, a hatch 6 for sealing the furnace tube 1,
A gas introducing pipe 7 for introducing a raw material gas, for example, SiH4 and PH3, into the furnace core tube 1, and a replenishing gas introducing pipe 8 for supplementing the raw material gas, for example, PH3, which has been reduced by the reaction on the exhaust side.
And a double pipe structure comprising an outer inner pipe 9a and an inner inner pipe 10 for introducing these source gases into the exhaust-side reaction section while suppressing the reaction.

The outer inner tube 9a has an upper part formed on the inner inner tube 10a.
The diameter of the upper portion is made narrower by narrowing the upper portion of the tube in a tapered shape so as to have the same inner diameter as that of the inner inner tube 10. The inner diameter of the narrowed portion is
Equal to the inner diameter of Further, the outer inner tube 9a and the inner inner tube 1
The gap between the inner pipe 9a and the outer pipe 9a may be such that back diffusion does not occur between the outer inner pipe 9a and the inner inner pipe 10, and is, for example, 300 mm.
About 50 mm with respect to the inner diameter of the inner tube. In addition, the length of the inner inner tube 10 is set to the middle of the boat 4, and the length of the outer inner tube 9a is set to be slightly longer than the top of the boat 4.

Next, the operation of the present invention will be described with reference to FIG. The vertical reduced pressure vapor phase epitaxy apparatus of the present invention has a structure in which source gases, for example, SiH4 and PH3 are introduced from the lower end of the furnace core tube 1 and flow to the exhaust side. There is always one direction from the gas introduction side to the exhaust side. Introduced source gases SiH4 and P
H3 is deposited on the wafer 3 and the inner wall of the inner inner tube 10, and the gas concentration decreases as the gas moves toward the exhaust side. in
In the case of -situP-doped Si, the uniformity of the P concentration in the furnace is reduced to 10 to 20%.

In order to suppress the film formation on the wafer 3 in the vicinity of the source gas introduction part, the present invention provides an inner tube having a double tube and a space between the divided outer inner tube 9a and the inner inner tube 10. The source gas, for example, PH3, is supplied to make up for a decrease in the source gas concentration. Therefore, in the present invention, the inner inner tube 1
By reducing the diameter of the outer inner tube 9a in a tapered shape from the portion where the 0 is interrupted, the raw material gas is merged from the narrowed portion, the exhaust conductance in the furnace core tube 1 is kept constant, and the reaction gas in the reactor is Can be kept constant.

As a result, in the embodiment of the present invention, the uniformity of the film quality including the wafer film thickness and the impurity concentration at each position in the furnace core tube has been improved to 5%. As described above, the present invention has been described with reference to the vertical type reduced pressure vapor phase epitaxy apparatus.

[0017]

A first effect of the present invention is that the film quality such as the grown film thickness of the wafer and the impurity concentration can be made uniform between the source gas introduction side and the exhaust side, thereby reducing manufacturing variations. The reason is that variations in the reaction gas concentration and the reaction pressure between the source gas introduction side and the exhaust side can be reduced, and the reaction speed can be made uniform.

A second effect is that it is possible to reduce variations in product reliability. The reason is that, as described in the first effect, it is possible to make the film thickness and film quality uniform.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vertical reduced pressure vapor deposition apparatus showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional vertical reduced pressure vapor deposition apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace tube 2 Heater 3 Wafer 4 Boat 5 Pump 6 Hatch 7 Gas introduction tube 8 Replenishment gas introduction tube 9, 9a Outer inner tube 10 Inner inner tube

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 16/00-16/56 H01L 21/205

Claims (5)

(57) [Claims] 1. A boat on which a wafer is mounted is loaded into a furnace core tube, an inner tube having a double tube structure surrounding the boat is installed between the boat and the furnace core tube, and the inside of the furnace core tube is depressurized and a reaction is performed. The gas is transferred between the outer inner pipe and the inner
In a reduced pressure vapor phase growth apparatus for growing a film on a wafer by being introduced inside , the outer inner tube of the double tube is extended, the extension is narrowed down to a tapered shape, and the tapered portion is tapered. A reduced-pressure vapor deposition apparatus having a double tube structure and a single tube structure at the other end. 2. The double tube according to claim 1, wherein the inside diameter of the outer tube is made equal to the inside diameter of the inner tube, and the distance between the wafer and the inside tube is constant. 2. The reduced pressure vapor phase growth apparatus according to 1. 3. A main reactant gas is introduced into the inner inner tube of the double tube, and a supplementary reactant gas for supplementing gas consumed in the reaction is introduced into a gap between the inner inner tube and the outer inner tube. The reduced-pressure vapor deposition apparatus according to claim 1, wherein 4. The method according to claim 1, wherein the main reactant gas and the supplementary reactant gas are combined at the tapered portion.
3 pressure chemical vapor deposition apparatus as claimed. 5. The boat according to claim 1, wherein the tapered portion is formed at a position facing a substantially central portion of the boat length.
The reduced pressure vapor phase growth apparatus according to the above.