JP2540776B2 - Method for manufacturing semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming a silicon oxide film by a liquid phase growth method.

[0002]

2. Description of the Related Art A method of forming a silicon oxide (hereinafter referred to as SiO ₂ ) film on a semiconductor substrate (hereinafter referred to as a wafer) using a liquid phase epitaxy method is a method of forming a Si film at a low temperature and with good coverage.
Since it is possible to form an O ₂ film, it has been widely used in recent years. In this method, as shown in the configuration diagram of FIG. 4, a treatment tank 6 is filled with a hydrosilicofluoric acid (H ₂ SiF ₆ ) aqueous solution 2, and the H ₂ SiF ₆ aqueous solution 2 is circulated and filtered by a pump 4 and a filter 5. _{2 Use a} film growth device. When the Al plate 1 is immersed as a reaction initiator, H
_{In the 2} SiF ₆ aqueous solution 2, the chemical reactions of the following formulas (1) and (2) occur.

H ₂ SiF ₆ + 2H ₂ O → SiO ₂ + 6HF (1) 6HF + Al → H ₃ AlF ₆ + 3 / 2H ₂ ↑ (2) As a result, HF in reaction formula (1) Since it is consumed, SiO ₂ is deposited. Here, when the wafer 3 is immersed in the processing bath 6 for a certain period of time, a Si film having a required film thickness is formed on the surface of the wafer 3.
An O _{2 film} is formed. A method of forming such a SiO ₂ film is described in, for example, Japanese Patent Application Laid-Open No. 62-20876.

[0004]

BRIEF Problem to be Solved] In the SiO ₂ film formation method on the conventional wafer, the wafer surface when the SiO ₂ particles resulting in H ₂ SiF ₆ in aqueous solution the wafer is removed from the H ₂ SiF ₆ aqueous solution Adhere in large quantities. There is a problem that the adhered SiO ₂ particles become particles and cause defects of the semiconductor device. In order to reduce the SiO ₂ particles, there is a method of using a ultrafiltration filter or a method of suppressing the turbulent flow of the H ₂ SiF ₆ aqueous solution on the wafer surface to reduce the adhesion of particles to the wafer.
r World) 1992.4.46. However, even with this method, since a large amount of particles are generated, it is difficult to reduce the adhesion of particles when taking out the wafer.

An object of the present invention is to provide a method of manufacturing a semiconductor device which can reduce the number of particles adhering to a wafer when a SiO ₂ film is formed by a liquid phase growth method.

[0006]

According to a first aspect of the present invention, there is provided a semiconductor device manufacturing method, wherein a semiconductor substrate is dipped in a hydrosilicofluoric acid solution in which a reaction initiator is dipped to form a silicon dioxide film on the semiconductor substrate. In the method for manufacturing a semiconductor device, the step of removing the reaction initiator and the step of depositing silicon dioxide on the hydrosilicofluoric acid solution are performed before the semiconductor substrate on which the silicon dioxide film is formed is taken out of the hydrosilicofluoric acid solution. The method is characterized by comprising a step of adding a suppressing amount of hydrofluoric acid and a step of removing the silicon dioxide particles remaining in the hydrosilicofluoric acid solution by circulation filtration.

The method of manufacturing a semiconductor device according to the second invention is a method of manufacturing a semiconductor device in which a semiconductor substrate is dipped in a hydrofluoric acid solution in which a reaction initiator is dipped to form a silicon dioxide film on the semiconductor substrate. A step of removing the reaction initiator after forming a silicon dioxide film thicker than a predetermined thickness and a step of etching the surface of the silicon dioxide film by adding hydrofluoric acid into the hydrosilicofluoric acid solution. It is characterized by that.

[0008]

The present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a SiO ₂ film growth apparatus used in an example of the present invention. In FIG. 1, 1 is an Al plate which is a solid reaction initiator, 2 is a H ₂ SiF ₆ aqueous solution which is a treatment liquid,
3 is a wafer, 4 is a pump that circulates the H ₂ SiF ₆ aqueous solution 2, 5 is a filter that filters the H ₂ SiF ₆ aqueous solution 2 sent by the pump 4, 6 is a processing tank, and 7 is HF added to the processing tank 6. It is an HF supply port.

Next, the operation of the SiO ₂ film growth apparatus and SiO ₂
A first embodiment of film formation will be described with reference to the SiO ₂ film growth processing flowchart of FIG.

With the H ₂ SiF ₆ aqueous solution 2 in the processing tank 6 being circulated and filtered by the pump 4 and the filter 5,
The Al plate 1 is dipped in the H ₂ SiF ₆ aqueous solution 2 to cause a SiO ₂ precipitation reaction. Next, the wafer 3 is immersed in the H ₂ SiF ₆ aqueous solution 2 in the processing bath 6 for a certain period of time to form a SiO ₂ film having a required film thickness on the surface of the wafer 3. Si of required film thickness
After forming the O ₂ film, the Al plate 1 is treated with H ₂ Si in the processing bath 6.
Take out from the F ₆ aqueous solution 2. Simultaneously with this, HF was added to the treatment tank 6 through the HF supply port 7, and the H ₂ SiF ₆ aqueous solution 2 was added.
Make sure that no new SiO ₂ particles are deposited inside.

The amount of HF added here will be specifically described. The total amount of Al dissolved in the H ₂ SiF ₆ aqueous solution 2 from the time when the Al plate 1 was immersed in the H ₂ SiF ₆ aqueous solution 2 to the time when it was taken out was 1000 mol, of which 800 m
ol Al and 4800 mol HF react to react with H ₃ Al
If it becomes F ₆ and H ₂ , it becomes 80 by the reaction formula (1).
This means that 0 mol of SiO ₂ was deposited. Then, SiO ₂ was deposited on the wafer 3 is 1 mol, the inner wall surface and the filter 5 SiO ₂ was inside the precipitation treatment tank 6 7
89 mol, 10 mol of SiO ₂ deposited as particles in the H ₂ SiF ₆ aqueous solution. Here, the Al plate 1 is set to H
After removal from the _{2 S} iF ₆ aqueous solution 2, when it is _left, of the total amount of Al dissolved in _H 2 S iF ₆ aqueous solution 2, Al of 200mol that did not react with HF 12
Since it reacts with 00 mol of HF to deposit 200 mol of SiO ₂ , if 1200 mol of HF is added, the HF consumed by the reaction with Al can be supplemented, and the deposition of new SiO ₂ can be suppressed.

[0012] Since the occurrence of new SiO ₂ particles is suppressed by adding such a HF, SiO ₂ particles precipitated in H ₂ SiF ₆ aqueous solution 2 at SiO ₂ film formation becomes a problem. The SiO ₂ particles are removed by circulating filtration of the H ₂ SiF ₆ aqueous solution 2 with the pump 4 and the filter 5.

Then, the wafer 3 is taken out of the H ₂ SiF ₆ aqueous solution 2.

As described above, according to the first embodiment, SiO
After forming the _two films, the precipitation of SiO ₂ was eliminated and the SiO _{2 in} the solution was removed.
By filtering the ₂ particles from the H ₂ SiF ₆ aqueous solution 2 of SiO ₂ number of particles adhering to when the wafer is removed 3 can be greatly reduced.

Next, a second embodiment of the present invention S shown in FIG.
This will be described with reference to the iO ₂ film growth processing flowchart. The configuration of the device used is the same as in FIG.

First, as in the first embodiment, while the H ₂ SiF ₆ aqueous solution 2 in the processing tank 6 is being circulated and filtered by the pump 4 and the filter 5, the H ₂ SiF ₆ aqueous solution 2 is Al.
The plate 1 is dipped to cause a SiO ₂ precipitation reaction. next,
The wafer 3 is immersed in the H ₂ SiF ₆ aqueous solution 2 in the processing tank 6 for a certain period of time, and the surface thereof is slightly thicker than the required film thickness of SiO 2.
₂ Form a film. For example, if the SiO ₂ film formation rate is 0.1μ
m / min, the required SiO ₂ film thickness is 100 μm, and the extra SiO ₂ film is about 5 μm, the wafer 3 is H ₂ Si.
It may be immersed in the F ₆ aqueous solution 2 for about 105 minutes.

Next, the Al plate 1 is treated with H ₂ SiF ₆ in the processing tank 6.
Remove from aqueous solution 2. At the same time, HF is added to the processing tank 6.
HF is added from the supply port 7 to change the chemical reaction in the H ₂ SiF ₆ aqueous solution 2 into a reaction that reduces SiO ₂ and then the wafer 3
The upper SiO ₂ film is etched by about 5 μm.

Next, a specific example will be described. The size and shape of the wafer 3 is a disk having a diameter of 150 mm, and only the surface (one side) on which the semiconductor device is formed on the surface of the wafer 3 is 105
It is assumed that a uniform SiO ₂ film of μm is formed, and the deposition efficiency on the wafer 3 at the time of this film formation is 0.1%. The weight of the SiO ₂ film having a thickness of 5 μm to be etched is about 2 × 10 ^−4.
g (3 × 10 ⁻⁶ mol).

3 × 10 ⁻⁶ mol of SiO ₂ was added to the wafer 3
To deposit on (100 / 0.1) × 3 × 10 ⁻⁶ =
3 × 10 ⁻³ mol of Al is required, and conversely wafer 3
The HF required to etch 3 × 10 ⁻³ mol of SiO ₂ deposited above is 6 × (3 × 10 ⁻³ ) = 1.8 ×
It is 10 ^-2 mol. Therefore, the amount of HF added is 1.8 × 10 ^-2 mol or more. 1.8 × 10 ^-2 mo
By adding more than 1 HF, S on the wafer 3
After etching the iO ₂ film to about 100 μm,
The wafer 3 is taken out of the H ₂ SiF ₆ aqueous solution 2. In the second embodiment, S formed once on the wafer
Since the SiO ₂ film is subjected to the slight etching, there is an effect that the SiO ₂ film adhering to the surface of the SiO ₂ film in a particulate form can be removed. Further, since the SiO ₂ deposited inside the filter or the SiO ₂ particles captured can be slightly etched, the effect of extending the life of the filter can be obtained. In addition, in the said Example, although the case where an Al board was used as a reaction initiator was demonstrated, it is not limited to this, Ni, Co, Zn, or these compounds may be used.

[0020]

As described above, according to the present invention, when the SiO ₂ film having a required film thickness is formed on the wafer surface, the reaction initiator is taken out from the H ₂ SiF ₆ aqueous solution and at the same time, HF is removed.
Is added to the H ₂ SiF ₆ aqueous solution to obtain new SiO 2.
_After suppressing the precipitation reaction of ₂ and removing SiO ₂ particles remaining in the H ₂ SiF ₆ aqueous solution by circulation filtration,
Since the wafer is taken out from the H ₂ SiF ₆ aqueous solution, there is an effect that the number of SiO ₂ particles attached to the wafer surface can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a SiO ₂ film growth apparatus used in an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the first embodiment of the present invention.

FIG. 3 is a flow chart for explaining a second embodiment of the present invention.

FIG. 4 is a block diagram of a conventional SiO 2 film growth apparatus.

[Explanation of symbols]

 1 Al plate 2 H2 SiF6 aqueous solution 3 Wafer 4 Pump 5 Filter 6 Processing tank 7 HF supply port

Claims (3)

(57) [Claims] 1. A method of manufacturing a semiconductor device, wherein a semiconductor substrate is dipped in a hydrofluoric acid silicic acid solution in which a reaction initiator is dipped to form a silicon dioxide film on the semiconductor substrate. Before the semiconductor substrate is taken out from the hydrofluoric acid solution, the step of taking out the reaction initiator, the step of adding to the hydrofluoric acid solution a hydrofluoric acid in an amount that suppresses the silicon dioxide deposition reaction, And a step of removing silicon dioxide particles remaining in the hydrogen acid solution by circulation filtration. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the amount of hydrofluoric acid added is such that the chemical reaction of the hydrosilicofluoric acid solution becomes a reaction to reduce silicon dioxide. 3. A method of manufacturing a semiconductor device, comprising: forming a silicon dioxide film on a semiconductor substrate by immersing the semiconductor substrate in a hydrofluoric acid solution in which a reaction initiator is dipped; A method of manufacturing a semiconductor device, comprising: a step of taking out the reaction initiator after forming a thick film; and a step of adding hydrofluoric acid to the hydrosilicofluoric acid solution to etch the surface of the silicon dioxide film. .