JPH01280309A - Vacuum cvd device - Google Patents

Abstract

PURPOSE:To control natural oxide film growth and to enable pure CVD film growth by providing a vacuum spare room. CONSTITUTION:A vacuum spare room 7 is provided. For instance, a reaction tube vacuum pump 4 and a vacuum spare room pump 13 continuously operate to hold a reaction tube 1 and a vacuum spare room 7 in vacuum condition. After a silicon substrate 6 is incorporated in a silicon substrate spare room 11, the spare room 11 is discharged through a silicon substrate spare room pump 14 to attain vacuum of the approximately same level as the spare room 7. A gate valve 12 is opened and the substrate 6 is automatically carried and mounted to a boat 5. After all the substrates 6 are mounted on the boat 5, the boat 5, the silicon substrate 6 and a boat supporting base 8 are inserted together into the reaction tube 1 until a cap 3 seals the reaction tube 1 completely through the operation of a driving section 9. A CVD film is thereafter grown inside the reaction tube 1.

Description

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

2. Description of the Related Art In recent years, as semiconductor devices have become more diverse, the processes in which low-pressure CVD equipment is applied in their manufacturing processes have also become more diverse.

A conventional low pressure CVD apparatus will be described below.

FIG. 2 is a schematic cross-sectional view of a conventional low-pressure CVD apparatus.
is a reaction tube, 2 is a heater, 3 is a lid for sealing the reaction tube (hereinafter referred to as a cap), 4 is a vacuum pump, 5 is a holding jig (hereinafter referred to as a boat), 6 is silicon forming a semiconductor device It is a board.

The operation of this reduced pressure CVD apparatus will be explained.

First, the boat 5 holding the silicon substrate 6 is placed in the reaction tube 1.
is introduced into the center of the reaction tube 1 from the inlet of the reaction tube 1, and the reaction tube 1 is sealed with the cap 3. Next, after reducing the pressure inside the reaction tube 1 using the vacuum pump 4, a reaction gas is introduced into the reaction tube 1. As a result, a CVD film is grown on the silicon substrate 6.

Problems to be Solved by the Invention However, in the above conventional configuration, the boat 5 is connected to the reaction tube 1.
When introducing into the silicon substrate 6, the inside of the reaction tube 1 and the vicinity of the entrance of the reaction tube 1 are heated to a high temperature, and since the reaction tube 1 is open to the atmosphere, a natural oxide film grows on the silicon substrate 6. It's in easy condition. Therefore, C directly on the silicon substrate 6.
When growing a VD film, there is a problem that a natural oxide film grows under the CVD film, changing the characteristics inherent to the CVD film, such as an apparent increase in the CVD film thickness and fluctuations in the dielectric constant of the CVD film. .

The present invention solves the above-mentioned conventional problems, and suppresses the growth of a natural oxide film, thereby enabling pure CVD film growth.

Means for Solving the Problem In order to solve this problem, the reduced pressure CVD apparatus of the present invention is provided with a vacuum preliminary chamber in front of the reaction tube.

Function: This vacuum preliminary chamber allows the reaction tube and the front thereof to be kept in a vacuum state at all times and prevents air from being drawn in, so that a high quality CVD film can be grown.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic sectional view of a reduced pressure CVD apparatus in an embodiment of the present invention. In Figure 1, 1 is a reaction tube, 2 is a heater, 3 is a cap, 4 is a vacuum pump, and 5 is a
6 is a boat, and 6 is a silicon substrate, which have the same structure as the conventional example. Further, 7 is a vacuum preliminary chamber, 8 is a boat support stand, 9 is a drive unit for the boat support stand (hereinafter referred to as the drive unit),
10 is a connecting rod between the boat support stand and the drive unit, 11 is a silicon substrate preliminary chamber, 12 is a gate valve (hereinafter referred to as gate valve) connecting the vacuum preliminary chamber and the silicon substrate preliminary chamber, 1
3 is a vacuum pump (hereinafter referred to as vacuum pre-chamber pump) for evacuating the vacuum pre-chamber, and 14 is a vacuum pump (silicon substrate pre-chamber pump) for evacuating the silicon substrate pre-chamber.

The operation of the low pressure CVD apparatus of this embodiment, that is, the method of growing a CVD film will be explained.

First, in FIG. 1, the reaction tube vacuum pump 4 and the vacuum preliminary chamber pump 13 are always operating, and the reaction tube 2 and the vacuum preliminary chamber 7 are kept in a vacuum state. After storing the silicon substrate therein, the silicon substrate preliminary chamber 11 is evacuated by the silicon substrate preliminary chamber pump 14, and after reaching the same level of vacuum as the preliminary chamber 7, the gate valve 12 is opened.
The silicon substrate 6 is mounted on the boat 5 by automatic transport. After all the silicon substrates are installed in the boat, the boat 5, silicon substrate 6, and boat support 8 are all inserted into the reaction tube 1 by the action of the drive unit 9 until the cap 3 completely seals the reaction tube 1. Ru. After this, inside the reaction tube 1, CV
DI is grown.

According to this embodiment, the silicon substrate 6 can be mounted on the boat 5 in the vacuum preliminary chamber 7, and the silicon substrate 6 is inserted into the reaction tube 1 in order to enclose the reaction tube 1 and its front part in a vacuum state. By suppressing the growth of natural oxide film during production, high quality and
A CVD apparatus capable of highly accurate film growth can be realized. Although the above embodiments have been described using a vertical CVD apparatus as an example, the shape of the reaction tube does not matter as long as the vacuum preliminary chamber is provided in front of the reaction tube.

Effects of the Invention According to the present invention, by providing a vacuum preliminary chamber in front of the reaction tube, it is possible to grow a film with high precision and quality, and to realize an excellent low pressure CVD apparatus.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a low-pressure CVD apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of a conventional low-pressure CVD apparatus. 1...Reaction tube, 2...Heater, 3.
... Cap, 4 ... Reaction tube vacuum pump, 5 ... Boat, 6 ... Silicon substrate, 7 ... Vacuum preliminary chamber, 8 ... Boat support stand, 9 ... Drive section, 10 ... Connection rod between boat support stand and drive section, 11 ... Silicon substrate preliminary chamber, 12・・・・・・Gate valve, 13...
...Vacuum preliminary chamber, 14...Silicon substrate preliminary chamber pump. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 2

Claims (1)

[Claims] A low-pressure CVD device equipped with a vacuum preliminary chamber.