JPH0543541U - Vertical diffusion device - Google Patents

Abstract

(57) [Summary] [Purpose] To eliminate the deviation of the flow of process gas in the reaction tube of the vertical diffusion device and to eliminate the variation in the film pressure generated on the wafer. A hollow donut-shaped exhaust flange 11 is provided below a reaction tube 2 of a vertical diffusion device, a required number of intake holes 14 are provided on an inner peripheral surface of the exhaust flange, and exhaust is provided at a required position on an outer peripheral surface of the exhaust flange. The pipe 13 is continuously provided, and the process gas supplied from the upper portion of the reaction pipe is exhausted from the exhaust pipe through the exhaust flange, and the process gas is dispersed and taken into the exhaust flange to prevent the process gas from being unbalanced. To do.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vertical diffusion device which is one of semiconductor manufacturing devices, and more particularly to a process gas exhaust device.

[0002]

[Prior Art]

 One of the semiconductor manufacturing processes is a diffusion process for diffusing impurities in a silicon wafer.

A conventional diffusion device will be described with reference to FIG.

In the figure, reference numeral 1 denotes a heater, and a reaction tube 2 is inserted and provided in the heater 1. Reference numeral 3 denotes an elevator arm of the boat lifting device, on which a boat 5 for holding wafers 4 in multiple stages in a horizontal state is placed, and when the elevator arm 3 is raised and lowered, the boat 5 is It is designed to be charged into the reaction tube 2. Further, the furnace lid 7 and the lower surface of the reaction tube 2 which are provided in the elevator arm 3 and close the lower end opening of the reaction tube 2 so that the inside of the reaction tube 2 becomes airtight when the boat 5 is loaded. Are sealed with a seal 6.

A process gas supply pipe 8 is provided at the lower end of the reaction tube 2 and extends to the upper part inside the reaction tube, and an exhaust port 9 is provided at the lower end of the reaction tube 2. .

Then, while the inside of the reaction tube 2 is heated by the heater 1 and the boat 5 is loaded in the reaction tube 2, the process gas is supplied from the process gas supply tube 8 and further. The diffusion process to the wafer 4 is performed by exhausting from the exhaust port 9.

[0007]

[Problems to be solved by the device]

 However, in the above-described conventional process gas exhaust device, the process gas supplied to the reaction tube 2 is exhausted collectively from the exhaust port 9 located on the opposite side to the position where the process gas is introduced. Therefore, in the vicinity of the exhaust port 9, the flow of the process gas was uneven. For this reason, the film pressure of the formed film varies between wafers, or even within the same wafer, the film pressure varies, resulting in a decrease in yield.

In order to improve the variation in the film pressure, the temperature inside the reaction tube 2 is biased by the heater 1 or the exhaust pressure is adjusted, but the adjustment is difficult and the reproducibility is poor, Moreover, it was not possible to improve the complete variation.

In view of the above situation, the present invention intends to eliminate the deviation of the flow of the process gas in the reaction tube and to eliminate the variation in the film pressure generated on the wafer.

[0010]

[Means for Solving the Problems]

 According to the present invention, a hollow donut-shaped exhaust flange is provided at the bottom of a reaction tube of a vertical diffusion device, a required number of intake holes are provided on the inner peripheral surface of the exhaust flange, and an exhaust pipe is provided at a required position on the outer peripheral surface of the exhaust flange. And the process gas supplied from the upper part of the reaction tube is exhausted from the exhaust pipe through the exhaust flange.

[0011]

[Action]

 The process gas introduced into the reaction tube descends along the axis of the reaction tube, is drawn into the exhaust flange from the intake hole of the exhaust flange, and is then exhausted from the exhaust tube. Since the required number of the intake holes are formed on the inner circumference of the exhaust flange, the process gas is dispersed and taken in, and the deviation of the exhaust flow is prevented.

[0012]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the same parts as those shown in FIG. 4 are designated by the same reference numerals.

In the present embodiment, a hollow donut-shaped exhaust flange 11 is provided at the lower end of the reaction tube 2, and the process gas is exhausted from the entire circumference of the exhaust flange 11, so that the lower portion of the reaction tube 2 is exhausted. This prevents uneven distribution of the gas flow.

Hereinafter, the exhaust flange 11 will be described in detail with reference to FIGS. 2 and 3.

The exhaust flange 11 has a substantially donut shape, and its cross-sectional shape is rectangular and hollow, and this hollow portion serves as an exhaust duct 15. An ear plate 12 for attaching to the lower surface of the reaction tube 2 is fixed to a required location on the upper edge of the outer peripheral surface of the exhaust flange 11, and the seal 6 is hermetically adhered to the lower surface of the exhaust flange 11. Further, an exhaust pipe 13 is continuously provided at a required position on the outer peripheral surface of the exhaust flange 11, and a required number of intake holes 14 are formed on the inner peripheral surface of the exhaust flange 11 at a predetermined pitch. The diameter of the intake hole 14 is increased as the distance from the position where the exhaust pipe 13 is connected is increased.

The process gas introduced into the process gas supply pipe 8 and introduced from the upper portion of the reaction pipe 2 descends along the axis of the reaction pipe 2, and the exhaust gas is exhausted from each intake hole 14 of the exhaust flange 11. The air reaches the duct 15 and is further exhausted through the exhaust pipe 13.

In the state where the process gas is sucked from each of the intake holes 14, since the intake hole 14 has a small diameter in the vicinity of the communication position of the exhaust pipe 13 and has a large diameter for a while as it goes away from the communication position, the exhaust gas is exhausted. The flow rate distribution is uniform over the entire circumference, and it is possible to prevent the deviation of the exhaust gas flow.

In the above embodiment, the intake holes 14 are formed at the same pitch and the diameter of the intake holes 14 is changed according to the position. However, the intake holes 14 are formed with the same diameter and the drilling pitch is changed. You may allow it. Alternatively, it is of course possible to change both the diameter of the intake holes 14 and the drilling pitch.

Needless to say, various changes can be made without departing from the scope of the present invention.

[0021]

[Effect of the device]

 As described above, according to the present invention, since the process gas is exhausted from the entire circumference of the lower part of the reaction tube, there is no unevenness in the exhaust flow, and therefore the film pressure between wafers or within the same wafer is reduced. Can be prevented, and the accuracy of film formation and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of an exhaust flange in the embodiment.

FIG. 3 is a view on arrow AA of FIG.

FIG. 4 is a schematic sectional view of a conventional example.

[Explanation of symbols]

 2 Reaction Pipe 11 Exhaust Flange 13 Exhaust Pipe 14 Intake Hole 15 Exhaust Duct

Claims (1)

[Scope of utility model registration request] 1. A hollow donut-shaped exhaust flange is provided below a reaction tube of a vertical diffusion device, a required number of intake holes are provided on an inner peripheral surface of the exhaust flange, and an exhaust tube is provided at a required position on an outer peripheral surface of the exhaust flange. And a process gas supplied from the upper part of the reaction tube is exhausted from the exhaust pipe through the exhaust flange.