JPH0358412A - Low pressure cvd method - Google Patents

Abstract

PURPOSE:To make it possible to maintain the uniformity of film thickness between the wafer surfaces and on the wafer surface by a method wherein a plurality of gas feeding holes are provided in one side-wall section of a reaction tube, and a plurality of gas discharge holes are provided in the other side-wall section of the reaction tube respectively in the axial direction of the reaction tube. CONSTITUTION:The title CVD device is equipped with a reaction gas feeding tube 2, having a plurality of gas feeding holes 15, provided in the inner wall section of a reaction tube 1, a discharge tube 3 having many discharge holes 14 in the axial direction of the reaction tube in the state wherein the discharge tube 3 is closely fixed to the reaction tube 1, a heat source with which the reaction tube 1 is heated up, a rotary pump 5 with which evacuation and pressure regulation are conducted, a mechanical booster pump 6 and a pressure regulator 7. To be more precise, reaction gas is fed by providing a plurality of reaction gas feeding holes 15 in one side wall section in the reaction tube 1, and besides, the reaction gas is discharged from the discharge holes 14 provided in the other side wall section of the reaction tube. Since the difference in concentration of gas between the front part and the rear part of the reaction tube 1 can be eliminated, uniformity of film thickness can be maintained over the surface of wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low pressure CVD apparatus used in the manufacturing process of semiconductor devices.

[Conventional technology]

Conventionally, low pressure CVD equipment deposits a polycrystalline silicon film or silicon dioxide (
Insulating films such as Si02) film, silicon nitride (SiJ4), and HTO (High
h Temperature Oxide) I15!
It is used in the katakai process such as. This will be further explained using Figure 5 below. First, the wafer 9 is loaded onto the boat 8 and placed in the reaction tube 1.
The heating source 4 is arranged so as to maintain a certain interval and a certain angle.
Heat it by Then, by supplying a reactive gas to the heated wafer surface from the reactive gas supply pipe 2, the above-mentioned thin film is formed by the thermal decomposition reaction of the reactive gas, and the vacuum exhaust system 11
Exhaust more gas.

In addition, in the case of mass production processing, the boat 8 shown in Fig. 6 (
The wafer jig shown in a) and (b) (hereinafter referred to as a basket boat) is used. The purpose of this is to make the film thickness uniform between the eight surfaces of the wafer and within the surface of the wafer.
3.

[Problem to be solved by the invention]

However, with the above-mentioned method of supplying and exhausting reactive gases in the conventional low-pressure CVD equipment, when mass-producing wafers, the concentration of the reactive gas is different between the front and rear wafers, resulting in poor film thickness uniformity between wafers. Lost. In addition, if you use the cage boat shown in Figure 6 to compensate for this,
Although the film thickness uniformity between wafers is improved, the film growth rate is reduced because the gas is supplied through the holes in the cage boat.
It has the disadvantage of reduced processing capacity.

An object of the present invention is to provide a reduced pressure CVD apparatus that eliminates the above-mentioned problems.

[Means to solve the problem]

The low pressure CVD apparatus of the present invention includes a reaction tube in which a semiconductor substrate is placed and processed, a reaction gas supply system that supplies a reaction gas to the reaction tube, a vacuum exhaust system that evacuates the inside of the reaction tube, and a heating system for heating the reaction tube. In a low pressure CVD apparatus having a heating source for transferring the semiconductor substrate and a transfer jig for transferring the semiconductor substrate, a reaction gas supply port is provided on one side wall of the reaction tube, and a gas exhaust port is provided on the other side wall of the reaction tube. A plurality of them are provided in the axial direction of the reaction tube.

〔Example〕

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

FIG. 1 is a schematic sectional view of a first embodiment of the present invention, and FIGS. 2 and 3 are an enlarged front view of the reaction tube and an enlarged top view of the reaction gas supply pipe in FIG. 1.

In FIG. 1, the reduced pressure CVD apparatus has a reaction gas supply tube 2 having a large number of gas supply ports 15 in the axial direction of the reaction tube on the inner wall of the reaction tube 1, and a reaction tube 1 that is in close contact with the reaction tube 1 on the other side wall of the reaction tube. In this state, an exhaust pipe 3 having a large number of exhaust ports 14 in the axial direction of the reaction tube (here, the exhaust pipe and the reaction tube communicate with each other through an exhaust port provided in the reaction tube 1 in the same way as the exhaust pipe 3), tube 1
The vacuum exhaust system includes a heat source 4 that heats the air, a rotary bomb 5 that performs exhaust and pressure adjustment, a mechanical booster pump 6, and a pressure regulator 7. The operating method of the first embodiment will be explained below with reference to FIGS. 1 to 3.

First, the wafer 9 is inserted into the reaction tube 1 using the boat 8 and wafer transfer jig 10 shown in FIG. Here reaction tube 1
The tube is open only on the front side, not the rear side like conventional reaction tubes. After inserting the wafer, the front opening is closed with a hatch. Next, the inside of the reaction tube 1 is reduced to a predetermined pressure by a vacuum evacuation system controlled by a rotary pump 5, a mechanical booster pump 6, and a pressure regulator 7, while a reaction gas is supplied to the inner wall of the reaction tube 1. A reaction gas is introduced into the reaction tube 1 through the tube 2, and a film is formed on the surface of the wafer 9. The supplied gas flows over the surface of the wafer 9 and is then exhausted through the exhaust pipe 3 provided on the side wall of the other reaction tube 1. Therefore, the reaction gas is in reaction tube 1
The flow will be perpendicular to the axial direction.

In conventional low-pressure CVD equipment, the gas flow was in the axial direction of the reaction tube, so the gas flow inside the reaction tube 1 became complicated.
Also, since the gas concentration differs between the front and rear parts,
Non-uniformity in film thickness between wafers and within the wafer surface is unavoidable. For example, in conventional low-pressure CVD equipment, if a cage boat is not used, the film thickness uniformity between the wafer surfaces deteriorates.
Although there is a limit of 50 wafers per process, according to the first embodiment, it is possible to process more than 100 wafers at a time. In addition, in order to maintain uniformity of film thickness, the cutting speed when using a force go boat is approximately 20 people/+++in.
In contrast, according to the first embodiment, 40 people/wi
It can be seen that it is possible to process at a certain length speed of n or more (twice), making it extremely difficult for mass production processing.

FIG. 4 is a schematic sectional view of a second embodiment of the present invention, in which the present invention is applied to a vertical reduced pressure CVD apparatus.

In this second embodiment as well, by providing the gas supply port 15 and the exhaust port 14 on the side wall of the reaction tube 1, the flow of the reaction gas is perpendicular to the axis of the reaction tube. Therefore, as in the first embodiment, there is an advantage that the film thickness uniformity between and within the wafer surfaces is maintained.

〔Effect of the invention〕

As explained above, the present invention provides a plurality of reaction gas supply ports on one side wall of a reaction tube to supply the reaction gas, and further exhausts the reaction gas through an exhaust port provided on the other reaction tube side wall. By configuring to do this, it is possible to eliminate the difference in gas concentration between the front and rear portions of the reaction tube, thereby maintaining the uniformity of the film thickness depending on the wafer position. This makes it possible to process a large number of wafers at once, and since the gas flow path is short, there is little gas turbulence and the reproducibility of certain film processes is excellent, making it very suitable for mass production processing.

[Brief explanation of drawings]

1 is a schematic sectional view of the first embodiment of the present invention, FIGS. 2 and 3 are an enlarged front view of the reaction tube and an enlarged top view of the reaction gas supply pipe in FIG. 1, and FIG. 4 is an enlarged top view of the reaction tube shown in FIG. FIG. 5 is a schematic cross-sectional view of a conventional low-pressure CVD apparatus, and FIG. 6 is a front view of a wafer jig used to improve film thickness uniformity in a conventional low-pressure CVD apparatus. and a side view. DESCRIPTION OF SYMBOLS 1... Reaction tube, 2... Reaction gas supply pipe, 3... Gas exhaust pipe, 4... Heat source, 5... Rotary bomb, 6... Mechanical booster pump, 7... Pressure regulator, 8...Boat, 9...Wafer, 10...
Wafer transfer jig, 11... Vacuum exhaust system, 12... Cylindrical boat, 13... Hole, 14... Exhaust port, 15.
...Gas supply port.

Claims (1)

[Claims] a reaction tube in which a semiconductor substrate is placed and processed; a reaction gas supply system that supplies a reaction gas to the reaction tube; a vacuum exhaust system that evacuates the inside of the reaction tube; and a heat source that heats the reaction tube;
and a transfer jig for transferring the semiconductor substrate.
A reduced pressure CVD apparatus in apparatus D, characterized in that a plurality of reaction gas supply ports are provided in one side wall of the reaction tube, and a plurality of gas exhaust ports are provided in the other side wall of the reaction tube in the axial direction of the reaction tube. .