JPH0441174Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reduced pressure vertical CVD apparatus that uniformly forms a CVD film on the surface of a wafer.

[Conventional technology]

Figure 4 is a simplified cross-sectional view showing an example of a conventional reduced pressure vertical CVD device, where 1 is a heating element, and 2 is this heating element 1.
3 is an internal reaction tube vertically installed inside the external reaction tube 2, and 7 is a reaction chamber cap. Reference numeral 9 denotes an elevator that moves the reaction chamber cap section 7 up and down, and by moving the cap section 7 up and down, the boat 10 placed on the cap section 7 can be taken in and out of the internal reaction tube 3. 11 is a large number of wafers held in the boat 10. 12 is a supply pipe for supplying raw material gas from below the internal reaction tube 3, and 5a is a gas control system inserted in the middle of this supply pipe 12. 4 is inner and outer reaction tubes 3 and 2
It is an exhaust pipe that exhausts air from the lower part between them, and 6 is a vacuum pump for exhaust.

In such a conventional apparatus, when the cap part 7 is moved upward by the elevator 9 and the boat 10 placed on the cap part 7 is introduced into the internal reaction tube (hot wall reaction chamber) 3, the inner and outer reaction tubes 3,
The lower part of the cap 2 is sealed with a cap part 7. When the vacuum pump 6 is driven in this state, the gas in the internal reaction tube 3 passes between the inner and outer reaction tubes 3 and 2, and is exhausted via the exhaust pipe 4, so that the inside of the internal reaction tube 3 becomes in a vacuum state.

Then, the raw material gas is controlled by the gas control system 5.
When the raw material gas is supplied from the lower part of the internal reaction tube 3 through the supply pipe 12 and the feed pipe 12, the raw material gas is exhausted by the vacuum pump 6 through the path shown by the arrow. In this process, CVD films are produced on the surfaces of a large number of wafers 11 supported by the boat 10 by chemical reaction in the gas phase.

[Problem that the invention attempts to solve]

However, in the conventional apparatus described above, when trying to process a large number of wafers 11, simply considering the height of the boat 10, the height of the heating element 1,
The height of the inner and outer reaction tubes 3 and 2 must also be increased, and the installation room must be a room with a high ceiling. There is a difference between the thickness of the film formed on the surface of the wafer and the thickness of the film formed on the surface of the wafer located above (the gas outflow side).
Not only will it be impossible to uniformly generate a CVD film on the surface of a large number of wafers, but also a large amount of reactants will adhere to the inner surface of the outer reaction tube 2 because the raw material gas flows along the inner surface of the outer reaction tube 2. However, there were problems in that flakes increased and cleaning frequency increased.

[Means for solving problems]

In order to solve the above-mentioned problems, the device of the present invention has an external reaction tube 2 vertically installed inside a heating element 1 as shown in FIGS. A plurality of internal reaction tubes 3 are arranged vertically around the exhaust pipe 4, and a plurality of internal reaction tubes 3 are placed vertically on the reaction chamber cap part 7 fitted into the exhaust pipe 4. A plurality of boats 10 supporting a large number of wafers 11 to be inserted were placed thereon, and raw material gas was supplied from below each internal reaction tube 3, and exhaust was exhausted from below an exhaust pipe 4 in the center. It is something.

[Effect]

Raw material gas is supplied from below a plurality of internal reaction tubes 3, and a boat 1 inserted into each internal reaction tube 3
0, flows downward from the upper end of the exhaust pipe 4 in the center, and is exhausted from the lower part of the exhaust pipe 4. During this process, CVD chemically reacted in the gas phase on the surfaces of a large number of wafers 11 supported by a plurality of boats 10.
A film is produced.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

Fig. 1 is a simplified cross-sectional view showing one embodiment of the device of the present invention, Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, and Fig. 3 is a diagram showing a plurality of boats mounted on the reaction tube cap of the present invention. It is a simplified perspective view showing a state.

In Figure 1, 1 is a heating element, 2 is this heating element 1
An external reaction tube 4 is vertically installed inside the external reaction tube 2, and 4 is an exhaust pipe installed vertically at the center of the external reaction tube 2. If this exhaust pipe 4 is made of metal, it will cause impurity contamination on the wafer, so to avoid this, it is covered with a cylindrical pipe 8 made of quartz. The exhaust pipe 4 is connected to a vacuum pump (not shown).

In this example, a plurality of internal reaction tubes, three in number (see FIG. 2), are installed vertically around the exhaust pipe 4.
As shown in the third diagram, three boats 10 supporting a large number of wafers 11 to be inserted into each internal reaction tube 3 are placed on the reaction chamber cap part 7 fitted into the exhaust pipe 4. . The reaction chamber cap 7 is moved up and down by an elevator 9.

The lower part of each internal reaction tube 3 is connected to a supply pipe 12, and the raw material gas is uniformly supplied into each internal reaction tube 3 by a gas control system 5.

In the above configuration, when the reaction chamber cap part 7 is moved upward by the elevator 9 and the three boats 10 placed on the cap part 7 are introduced into each internal reaction tube 3, each of the inner and outer reaction tubes 3, 2 It is sealed with a cap part 7 below. When the vacuum pump (not shown) is operated in this state, the inner and outer reaction tubes 3,
The gas between the reaction tubes 2 and 2 is exhausted from the upper side of the exhaust pipe 4 to the lower side, and the insides of the inner and outer reaction tubes 3 and 2 are brought into a vacuum state.

When the raw material gas is introduced into the main pipe 13, the raw material gas is uniformly supplied into each internal reaction tube 3 through the supply pipe 12 by the gas control system 5, and this supplied raw material gas is supplied to a large number of wafers as shown by the arrows. 11 and the inner periphery of each internal reaction tube 3.
Air is exhausted from above to below.

During this evacuation process, CVD films are produced on the surfaces of a large number of wafers 11 supported by three boats 10 by chemical reaction in the gas phase. The uniformity of the thickness of this CVD film, particularly of SiO ₂ , PSG, and doped polysilicon films, depends on the gap between the internal reaction tube 3 and the wafer 11, but by making the gap appropriate, SiO ₂ , PSG, doped polysilicon, etc. can also be produced with uniform thickness.

In addition, in this invention, although it becomes larger in the horizontal direction, it does not become larger (does not become taller) in the vertical direction.
Therefore, there is no need for the installation room to be a room with a high ceiling, and it is located below each boat 10 (gas inflow side).
There is no difference in the thickness of the film formed on the surface of the wafer located at the upper position (gas outflow side) and the thickness of the film formed on the surface of the wafer located at the upper position (gas outlet side), and there is no uniformity on the surface of a large number of wafers. Can produce CVD films well.

Furthermore, since the raw material gas flows along the inner surface of each internal reaction tube 3 and is exhausted from the central exhaust pipe 4, the amount of reactants adhering to the inner surface of the outer reaction tube 2 is reduced, flakes are reduced, and cleaning frequency is reduced. can be reduced.

[Effect of idea]

That is, according to the present invention, not only can a CVD film be formed with good uniformity on the surface of a large number of wafers 11, but also the amount of reactants adhering to the inner surface of the external reaction tube can be reduced, flakes can be reduced, and cleaning frequency can be reduced. can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a simplified cross-sectional view showing one embodiment of the device of the present invention, Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, and Fig. 3 is a diagram showing a plurality of boats mounted on the reaction tube cap of the present invention. FIG. 4 is a simplified perspective view showing the state, and FIG. 4 is a simplified sectional view showing an example of a conventional reduced pressure vertical CVD apparatus. DESCRIPTION OF SYMBOLS 1... Heating element, 2... External reaction tube, 3... Internal reaction tube, 4... Exhaust pipe, 7... Reaction chamber cap part, 10... Boat, 11... Wafer.

Claims (1)

[Scope of utility model registration request] An external reaction tube 2 is installed vertically inside the heating element 1, an exhaust pipe 4 is installed vertically in the center of the external reaction tube 2, and a plurality of internal reaction tubes 3 are arranged around the exhaust pipe 4. A plurality of boats 10 supporting a large number of wafers 11 to be inserted into each internal reaction tube 3 are placed on the reaction chamber cap part 7 which is vertically installed and fitted into the exhaust pipe 4. A reduced-pressure vertical CVD device configured to supply raw material gas from below 3 and exhaust from below an exhaust pipe 4 in the center.