JPH07122530A - Production of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for producing a semiconductor wafer in which the yield can be increased by protecting the surface of a semiconductor wafer against contamination. CONSTITUTION:Oxides are removed from the surface of a semiconductor wafer 3 by etching with a hydrofluoric acid processing liquid 5 having composition of H2O:HF=50-100:1. The semiconductor wafer 3 is then immersed into a second hydrofluoric acid processing liquid 13 having composition of H2O:HF=400-1000:1 before it is cleaned with pure water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to cleaning of an oxide film on a semiconductor wafer after wet etching.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a structure of a conventional semiconductor wafer, and FIG. 4 is a view showing a manufacturing process of the semiconductor wafer in FIG. In the figure, 1 is a semiconductor substrate made of Si, 2 is an oxide film made of SiO ₂ laminated on the semiconductor substrate 1, 3 is a semiconductor wafer made of the semiconductor substrate 1 and oxide film 4, 4 is an oxide film removal tank, Reference numeral 5 is a hydrofluoric acid treatment liquid containing H ₂ O: HF = 50 to 100: 1 stored in the oxide film removal tank 4, and 6 is a pure water tank in which pure water 7 is stored.

Next, a method of manufacturing a semiconductor device will be described with reference to FIG. First, as shown in FIG. 4A, the semiconductor wafer 3 as shown in FIG. 3 is immersed in the hydrofluoric acid treatment liquid 5 in the oxide film removing tank 4 for a desired time to etch the oxide film 2. At this time, as shown in FIG. 5, the oxide film 2 on the semiconductor substrate 1 has the surface thereof and the hydrofluoric acid treatment liquid 5 and the following formula (1).
The reaction 8 shown in FIG. SiO ₂ + 6HF → H ₂ SiF ₆ + 2H ₂ O ...
(1) Then, in the boundary layer 10 formed on the semiconductor wafer 3, a large amount of reaction 8 occurs when the oxide film 2 is etched, so that a large amount of H ₂ SiF ₆ 9 is generated and the concentration becomes high. ing.

Next, the semiconductor wafer 3 having the oxide film 2 etched by etching is taken out and immersed in pure water 7 in a pure water tank 6 as shown in FIG.
The hydrofluoric acid treatment liquid 5 and foreign substances adhering to the are cleaned. At this time, since a large amount of water is supplied to the boundary layer 10 on the semiconductor wafer 3 as shown in FIG. 6, even though the oxide film 2 is etched, the reaction 1 as shown by the following formula (2)
1 slightly occurs, and a small amount of silica SiO ₂ is generated on the semiconductor wafer 3. H ₂ SiF ₆ + 2H ₂ O → SiO ₂ + 6HF ...
(2) Then, the finally cleaned semiconductor wafer 3 is taken out and dried.

[0005]

In the conventional method of manufacturing a semiconductor device, since the semiconductor wafer 3 from which the oxide film 2 has been removed as described above is immersed in pure water 7 for cleaning, the reaction 11 occurs. Since a small amount of silica SiO ₂ is dried while being chemically attached to the semiconductor wafer 3, there is a problem that the surface of the semiconductor wafer 3 is contaminated and the yield is reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a method of manufacturing a semiconductor device capable of preventing the surface of a semiconductor wafer from being contaminated and improving the yield. And

[0007]

[Means for Solving the Problems] Claim 1 according to the present invention
In the method for manufacturing a semiconductor device, the oxide film on the semiconductor wafer is
₂ O: HF = 50 to 100: 1 Etching is performed with the first hydrofluoric acid-based processing solution to remove H from the semiconductor wafer.
₂ O: HF = 400 to 1000: 1 The second hydrofluoric acid-based treatment liquid is used for cleaning, and this semiconductor wafer is cleaned with pure water.

[0008]

In the method of manufacturing a semiconductor device according to the first aspect of the present invention, a semiconductor wafer having an oxide film etched by the first hydrofluoric acid treatment liquid is treated with HF from the first hydrofluoric acid treatment liquid.
Of the H ₂ SiF ₆ in the boundary layer formed on the semiconductor wafer by decreasing the concentration of H ₂ SiF ₆ in the boundary layer formed on the semiconductor wafer by cleaning the semiconductor wafer with pure water after cleaning with the second hydrofluoric acid treatment solution having a low concentration of This prevents the generation of silica SiO ₂ on the semiconductor wafer in pure water.

[0009]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1A to 1D are views showing manufacturing steps of a semiconductor device according to a first embodiment of the present invention. In the figure, the same parts as those in the conventional case are designated by the same reference numerals, and the description thereof will be omitted. 12 is an intermediate cleaning tank, 13 is H ₂ O, which is stored in the intermediate cleaning tank 12 and has a lower HF concentration than the hydrofluoric acid treatment liquid 5:
It is a second hydrofluoric acid treatment liquid with HF = 400 to 1000: 1.

Next, a method of manufacturing the semiconductor device according to the first embodiment will be described with reference to FIG. First, as in the conventional case, as shown in FIG. 1A, the semiconductor wafer 3 is immersed in the hydrofluoric acid treatment solution 5 in the oxide film removing tank 4 for a desired time to etch the oxide film 2. At this time, as shown in FIG. 5, the oxide film 2 on the semiconductor substrate 1 causes a reaction 8 with the hydrofluoric acid treatment liquid 5 on the surface thereof as shown by the above formula (1). Then, in the boundary layer 10 formed on the semiconductor wafer 3, many reactions 8 occur when the oxide film 2 is etched, so that a large amount of H ₂ SiF ₆ 9 is generated and the concentration is high.

Next, the semiconductor wafer 3 from which the oxide film 2 has been removed by etching is taken out and immersed in the second hydrofluoric acid treatment liquid 13 in the intermediate cleaning tank 12 for intermediate cleaning as shown in FIG. 1B. To do. At this time, since HF is contained in the second hydrofluoric acid treatment liquid 13, the reaction 11 does not occur in the boundary layer 10 on the semiconductor wafer 3 (silica SiO ₂ is not generated), and the second H _{2 in} the hydrofluoric acid treatment solution 13 of
O reduces the concentration of H ₂ SiF ₆ 9 in the boundary layer 10.

Then, the semiconductor wafer 3 is taken out, and as shown in FIG.
As shown in (c), it is immersed in pure water 7 in a pure water tank 6. At this time, since only a trace amount of H ₂ SiF ₆ 9 remains in the boundary layer 10, the reaction 11 does not occur, and the second hydrofluoric acid treatment liquid 13 and foreign matter adhering to the semiconductor wafer 3 are pure water 7 It is washed in. Finally, the cleaned semiconductor wafer 3 is taken out and dried.

In the semiconductor device of Example 1 manufactured by the method as described above, the semiconductor wafer 3 from which the oxide film 2 has been removed is dipped in the second hydrofluoric acid treatment solution 13 for cleaning, and the semiconductor wafer 3 on the semiconductor wafer 3 is cleaned. Since the concentration of H ₂ SiF ₆ 9 in the boundary layer 10 is lowered, the reaction 11 on the semiconductor wafer 3 in pure water 7
Is suppressed and silica SiO ₂ is not generated, so that the surface of the semiconductor wafer 3 is not contaminated.

Example 2. 2A to 2D are views showing a manufacturing process of a semiconductor device according to a second embodiment of the present invention. In the figure, the same parts as those in the first embodiment are designated by the same reference numerals and omitted. Reference numeral 14 is a shower for discharging the second hydrofluoric acid treatment liquid 13 for cleaning the semiconductor wafer 3 from which the oxide film 2 has been removed.

Next, a method of manufacturing the semiconductor device according to the second embodiment will be described with reference to FIG. First, as in the first embodiment, as shown in FIG. 2A, the semiconductor wafer 3 is immersed in the hydrofluoric acid treatment liquid 5 in the oxide film removing tank 2 for a desired time to etch the oxide film 2. At this time, in the boundary layer 10 formed on the semiconductor wafer 3, H ₂ SiF ₆ 9 is used as in the case of the first embodiment.
Has a high concentration.

Next, the semiconductor wafer 3 from which the oxide film 2 has been removed is taken out and, as shown in FIG.
Then, the second hydrofluoric acid treatment liquid 13 is sprayed onto the semiconductor wafer 3 to perform intermediate cleaning. At this time, since HF is contained in the second hydrofluoric acid treatment liquid 13, reaction 11 does not occur in the boundary layer 10 on the semiconductor wafer 3 (silica SiO ₂
H in the second hydrofluoric acid treatment solution 13
The concentration of H ₂ SiF ₆ 9 in the boundary layer 10 is diluted by ₂ O.

Then, the semiconductor wafer 3 is immersed in pure water 7 in a pure water tank 6 as shown in FIG. 2 (c). At this time, since only a trace amount of H ₂ SiF ₆ 9 remains in the boundary layer 10, the reaction 11 does not occur, and the second hydrofluoric acid treatment liquid 13 and foreign matters adhering to the semiconductor wafer 3 are cleaned. . Finally, the cleaned semiconductor wafer 3 is taken out and dried.

In the semiconductor device of Example 2 manufactured by the above method, the semiconductor wafer 3 from which the oxide film 2 has been removed is washed by spraying the second hydrofluoric acid treatment liquid 13 from the shower 14 to clean the semiconductor wafer. Since the concentration of H ₂ SiF ₆ 9 in the boundary layer 10 on the upper surface of the semiconductor wafer 3 is reduced, the same effect as that of the above-described first embodiment is obtained, and the semiconductor wafer 3 is always treated with the new second hydrofluoric acid treatment solution 13. Since the surface of the semiconductor wafer 3 is cleaned, the surface of the semiconductor wafer 3 is not further contaminated.

Example 3. In each of the above-described embodiments, an example in which the hydrofluoric acid treatment liquid 5 composed of H ₂ O and HF is used to remove the oxide film 2 of the semiconductor wafer 3 has been described, but the present invention is not limited to this, and H ₂ O Even if a hydrofluoric acid-based treatment liquid composed of HF and NH ₄ F is used, the same effects as those in the above-mentioned respective embodiments can be obtained.

[0020]

As described above, according to claim 1 of the present invention, the oxide film of the semiconductor wafer is formed into H ₂ O: HF = 50 to 10
This semiconductor wafer was etched with a first hydrofluoric acid-based processing solution of 0: 1 to produce H ₂ O: HF = 400 to 100
Since the semiconductor wafer is cleaned with the second hydrofluoric acid-based treatment liquid of 0: 1 and this semiconductor wafer is cleaned with pure water, the surface of the semiconductor wafer can be prevented from being contaminated and the yield can be improved. There is an effect that a semiconductor device manufacturing method that can be performed can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a semiconductor device according to a first embodiment of the invention.

FIG. 2 is a diagram showing a manufacturing process of a semiconductor device according to a second embodiment of the invention.

FIG. 3 is a sectional view showing a structure of a conventional semiconductor wafer.

FIG. 4 is a diagram showing a manufacturing process of the semiconductor wafer in FIG.

FIG. 5 is a diagram showing a reaction on a surface of a semiconductor wafer during etching of an oxide film on the semiconductor wafer.

FIG. 6 is a diagram showing a reaction on the surface of a semiconductor wafer when the semiconductor wafer is washed with pure water.

[Explanation of symbols]

 2 oxide film 3 semiconductor wafer 5 hydrofluoric acid treatment liquid 7 pure water 13 second hydrofluoric acid treatment liquid 14 shower

Claims (1)

[Claims] 1. An oxide film on a semiconductor wafer is formed of H ₂ O: HF =
A step of etching with a first hydrofluoric acid-based treatment liquid of 50 to 100: 1, and a second step of H ₂ O: HF = 400 to 1000: 1 after the above steps.
And a step of washing the semiconductor wafer with pure water, the method of manufacturing a semiconductor device.