JPH06120207A - Method of forming insulating film - Google Patents

Abstract

(57) [Abstract] [Purpose] An interlayer insulating film can be formed by forming the interlayer insulating film in the same device, which can reduce the time required for carrying the device from one device to another and cleaning the processing target. Providing a method. [Structure] The wafer S is placed in a chamber maintained at 850 ° C. to form a SiO ₂ film (step S22). TEOS, B ₂ O ₃ , P ₂ P at the same temperature in the same equipment
₃ is introduced to form a BPSG film (step S2
3). Then, after forming the BPSG film, the introduction of these reaction gases is stopped and the heat treatment of the third step is performed (step S24). After this heat treatment, a SiO ₂ film is formed in the same apparatus at approximately the same temperature (step S25), and the film formation state is inspected (step S26).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for manufacturing a silicon semiconductor device, and more particularly to a method for forming an insulating film.

[0002]

2. Description of the Related Art Borophosphosilicate glass film (hereinafter referred to as B
The PSG film) is used as an insulating film of a silicon semiconductor device because it has a characteristic of softening itself and exhibiting good flatness when heat-treated at a high temperature. BP
In the case of forming the SG film, an insulating film containing no impurities,
For example, SiO ₂ films are formed on the upper and lower layers of the BPSG film. This is to prevent impurities in the BPSG film from diffusing into the base on which the insulating film is formed and the metal wiring formed on the insulating film, for example.

FIG. 3 shows a conventional procedure for forming an insulating film.
It is a flowchart. On the wafer based on Figure 3
The process of forming the border film will be described. First, clean the wafer
(Step S31), this wafer is placed in
The reaction temperature is 350 to 400 ℃, the reaction gas is TEOS (Si (O
C₂H_Five)_Four), O₃And S by the atmospheric pressure CVD method.
iO₂A film is formed (step S32). Of this wafer
SiO₂The state of film formation is inspected and washed (step S
33). Then, the wafer is transferred into the CVD apparatus and the reaction temperature
The temperature is 350-400 ℃, TEOS (Si (OC₂
H_Five)_Four), O ₃, TMP (Tri Metyl Phosphate, P
O (OCH₃)₃) An organic liquid source containing P, such as
And TMB (Tri Metyl Borate, B (OCH₃)₃)of
Atmospheric pressure CVD method using an organic liquid source containing B
To form a BPSG film (step S34),
The state of formation of the BPSG film is inspected and cleaned (step S
35).

This wafer is heat-treated in a heating furnace at 850 to 1000 ° C. to flatten the BPSG film (step S3
6), inspection and cleaning are performed (step S37). And
The wafer is again transported into the CVD apparatus, a SiO ₂ film is formed by the atmospheric pressure CVD method (step S38), and the film formation state is inspected (step S39).

The SiO ₂ film and the BPSG film may be formed by a low pressure CVD method at 700 to 800 ° C. using a vertical furnace.

[0006]

In the steps of forming the insulating film as described above, the respective films are formed by using different apparatuses. This is because the impurities contained in the reaction gas supplied in the step of forming the BPSG film in step S34 are mixed in the steps after step S34 and are deposited on the BPSG film.
The purpose is to prevent the impurities from being mixed into the iO ₂ film. Since each film is formed by using a different apparatus, the wafer is cleaned every time it is transferred from the apparatus to the apparatus, or the transfer and cleaning are performed. Had to spend a lot of time on.

Since the BPSG film itself has hygroscopicity, it is sensitive to humidity, and if it absorbs moisture before the heat treatment, the BPSG film may be decomposed. Therefore, it is necessary to strictly control the conditions related to time and humidity from the film forming process of the BPSG film to the heat treatment process,
There is a problem that each device used in the film forming process must be strictly controlled.

In order to solve this problem, an apparatus for carrying out a BPSG film forming step and a heat treatment step in the same reaction apparatus has been developed and marketed by Lam Research.
This apparatus is a batch type depressurization type thermal CVD apparatus, has a horizontal transfer system, and can process a plurality of wafers at a time. The temperature for forming the conventional BPSG film is atmospheric pressure CVD.
350-400 ℃ in the case of the method, 700-400 in the case of the low pressure CVD
Although the temperature is 800 ℃, in the proposed device, by covering the reaction chamber with a heat shield having heat resistance,
A high temperature of 0 ° C can be maintained. Further, the reaction gas can be efficiently and rapidly exhausted, and due to this high temperature and high-speed exhaustion, the BPSG can be heated at about the same temperature as the heat treatment temperature
Since a film is formed, by stopping the supply of the reaction gas, B
The PSG film can be subjected to heat treatment, and the heat treatment process can be performed in the same apparatus.

The present invention uses such a device to provide a BPS
Focusing on the fact that a G film can be formed in the same device, BPSG
By forming the insulating film in the same device, including the process of forming the insulating film before and after the film is formed, the time required for carrying from device to device and accompanying cleaning of the processing target can be omitted. An object of the present invention is to provide a method for forming an insulating film that can be used.

[0010]

A method of forming an insulating film according to the present invention is a method of forming an insulating film containing a BPSG film on a base by using a CVD method, wherein impurities existing in the BPSG film are removed. A first step of forming a first insulating film on the underlayer to prevent diffusion to the underlayer; a second step of forming the BPSG film on the first insulating film at a predetermined temperature; and a BPSG film A third step of performing a heat treatment at about the same temperature as the second step, and a fourth step of forming a second insulating film on the BPSG film for preventing the impurities from diffusing thereon.
And the first, second, third, and fourth steps are performed in the same apparatus.

[0011]

In the method of forming an insulating film of the present invention, since the BPSG film is formed at substantially the same temperature as the heat treatment step performed at a high temperature, the impurities contained in the reaction gas for forming the BPSG film are sufficient. The oxidation reaction is performed, and byproducts due to impurities contained in the unreacted gas and the reaction gas are not generated. Thus, even if the step of forming the second insulating film, which is a post-step of forming the BPSG film, is performed in the same apparatus as the BPSG film forming step, impurities are not mixed. Further, since no impurities remain in the apparatus after the insulating film is formed, impurities will not be mixed in even if the step of forming the first insulating film for the next processing target is performed in the same apparatus. Thereby, the first, second, third, and fourth steps can be performed in the same apparatus.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic sectional view of a CVD apparatus used for carrying out the method of the present invention. In the figure, 1 is a cylindrical chamber, in which an exhaust tube 1h is formed in the center, and a disk-shaped mounting table 2 for mounting a plurality of wafers S, S ... A heater 3 is disposed below the mounting table 2, and disc-shaped heat shields 4 and 4 having heat resistance are fitted to the upper side of the mounting table 2 and the lower side of the heater 3. A reaction gas inlet 1g is formed on the side wall of the chamber 1 so that the reaction gas can flow into a region surrounded by the mounting table 2 and the heat shield 4, that is, the reaction chamber. This reaction chamber has a smaller reaction chamber volume than the conventional CVD apparatus, and the introduced reaction gas and the gas after the reaction flow out to the exhaust stack 1h at a high speed. A transfer chamber (not shown) is connected to the side surface of the chamber 1. Inside the transfer chamber, a wafer cassette arranged outside the chamber 1 and a transfer robot for transferring the wafer S between the chambers 1 are arranged. There is. The wafer is transferred onto the mounting table 2 by this horizontal transfer system.

When an insulating film is formed on the wafer S with such an apparatus, the wafer S to be processed is placed on the placing table 2 by the above-mentioned transfer robot, and the chamber 1 is evacuated and evacuated. The inside of the chamber 1 is maintained at a predetermined vacuum degree, and the inside of the chamber 1 is maintained at a predetermined temperature by heating the heater 3. Then, the reaction gas is introduced into the reaction chamber through the reaction gas inlet 1g, the wafer S on the mounting table 2 is subjected to a film forming process, and the gas after the reaction is exhausted from the exhaust tube 1h. The flow path of the reaction gas is as shown by the white arrow in the figure.

FIG. 2 is a flow chart showing the procedure for forming an insulating film by the method of the present invention. The process of forming the BPSG film and the SiO ₂ film on the wafer will be described based on this flowchart. First, the wafer S is cleaned (step S21), the wafer S is placed on the mounting table 2 in the CVD apparatus shown in FIG. 1, the chamber 1 is depressurized, and the reaction chamber is maintained at 850 ° C. Then, a SiO ₂ film which is an insulating film in the first step is formed (step S22). TEOS, O ₂ or SiH ₄ , N ₂ O is used as the reaction gas. At this time, the heat shields 4, 4 arranged in the chamber 1
Heat is confined in chamber 1 by
Can be maintained at

Then, in the second step, TEOS and TEB (Tri Ethyl Bor
ate, B (OC ₂ H ₅ ) ₃ ), PH ₃ , and O ₂ are introduced to form a BPSG film (step S23). At this time, as described above, the introduced reaction gas and the gas after the reaction flow out to the exhaust stack 1h at a high speed, so that by-products due to impurities in the reaction gas are not formed and the unreacted gas is not formed. Is rapidly exhausted, so that no impurities remain in the reaction chamber.

After forming the BPSG film, the introduction of these reaction gases is stopped and the heat treatment of the third step is performed (step S24). After this heat treatment, as the fourth step, TEOS, O ₂ or Si is produced in the same apparatus at approximately the same temperature.
A reaction gas of H ₄ and N ₂ O is introduced to form a SiO ₂ film (step S25), and the film formation state is inspected (step S).
26).

The insulating film composed of different kinds of insulating films formed in the same apparatus as described above is formed to have the same film quality and flatness as compared with the conventional insulating film.

[0018]

As described above, according to the method for forming an insulating film of the present invention, since the BPSG film and the insulating film containing no impurities are formed in the same apparatus, the apparatus is carried from one apparatus to another and the processing associated therewith. The present invention has excellent effects such that the time for cleaning the target can be omitted.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a CVD apparatus used for carrying out the method of the present invention.

FIG. 2 is a flowchart showing a procedure for forming an insulating film by the method of the present invention.

FIG. 3 is a flowchart showing a procedure for forming a conventional insulating film.

[Explanation of symbols]

 1 chamber 1h exhaust stack 1g reaction gas inlet 2 mounting table 3 heater 4 heat shield

Claims (1)

[Claims] 1. A method of forming an insulating film including a BPSG film on a base by using a CVD method, wherein a first insulating film for preventing impurities existing in the BPSG film from diffusing to the base is formed on the lower surface. First to form on the ground
A step, a second step of forming the BPSG film on the first insulating film at a predetermined temperature, a third step of heat-treating the BPSG film at approximately the same temperature as the second step, and the impurities above the first step. A second insulating film for preventing diffusion into the BPSG.
And a fourth step of forming on the film, the first, second, third,
A method for forming an insulating film, which comprises performing four steps in the same apparatus.