JPH06120190A - Semiconductor substrate processing method - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the growth of natural oxide film, the adhesion of fine particles, and the deposition of metal ions when the semiconductor substrate is rinsed with pure water. [Structure] A semiconductor substrate after chemical treatment is treated with pure water containing 10 to 50 ppm of hydrogen fluoride and 10 to 50 ppm of hydrogen peroxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a semiconductor substrate, and more particularly to a method for rinsing a semiconductor substrate treated with a chemical solution with pure water.

[0002]

2. Description of the Related Art In a conventional method of rinsing a semiconductor substrate with pure water, 10 to 50 ppm of hydrogen fluoride (HF) is added to pure water (hereinafter referred to as HF-added pure water). By adding a very small amount of HF in this way, the effects of suppressing the growth of the natural oxide film on the semiconductor substrate, sterilizing, preventing the adhesion of fine particles, and preventing the deposition of metal ions are obtained as compared with pure water without addition. .

Further, in order to obtain a larger effect of preventing the adhesion of fine particles, CO ₂ is added to pure water (hereinafter referred to as CO ₂ -added pure water).

[0004]

Although this conventional method for treating a semiconductor substrate with pure water containing HF is superior to pure water without addition, the effect of preventing metal ion deposition is insufficient.

Further, the conventional CO ₂ -added pure water has no effect of preventing metal ion deposition, and ions of metal impurities accumulated in pure water due to continuous treatment of the semiconductor substrate tend to adhere to the surface of the semiconductor substrate. There was a point.

[0006]

A method for treating a semiconductor substrate according to the present invention is a method for treating a semiconductor substrate, wherein the semiconductor substrate is chemically treated and then rinsed with pure water.
10 to 50 ppm of hydrogen fluoride and 10 to 5 in the pure water
0 ppm of hydrogen peroxide or ozone is added.

[0007]

EXAMPLES Examples of the present invention will be described below.

The semiconductor substrate is immersed in a 1% dilute HF solution,
After removing the silicon oxide film on the surface of the substrate, HF and hydrogen peroxide (H ₂ O ₂ ) are added to pure water (hereinafter referred to as HF / H ₂ O ₂ added pure water) in an amount of 10 to 50 ppm to 5-2.
Rinse for 0 minutes and dry. It is known that generally used cleaning liquids HF, HCl / H ₂ O _{2 and the} like are relatively concentrated acids and alkalis, so that ions derived from the cleaning liquid are adsorbed on the surface of the semiconductor substrate, which deteriorates device characteristics. After the treatment, rinse with pure water is performed. The HF / H ₂ O ₂ added pure water in the first embodiment adds a new added value to this rinse pure water.

FIG. 1 shows a change over time in natural oxide film growth measured by X-ray photoelectron spectroscopy when the semiconductor substrate was left in the atmosphere after the rinsing step of this example. Examples A, B and C in which pure water without addition, pure water with CO _{2 and} pure water with HF were respectively used for the rinse treatment are also shown. HF / H ₂ O
_{In the} example using the pure water with ₂ added, the growth of the natural oxide film was suppressed as compared with the pure water without added and the pure water with CO ₂ added.
It can be seen that it is almost equivalent to the added pure water. Therefore, by using the rinse treatment of this embodiment immediately before the gate thermal oxidation, it is possible to suppress the increase in the effective film thickness and suppress the growth of the natural oxide film that deteriorates the withstand voltage of the gate oxide film. is there. This effect is small when the addition concentration of HF and H ₂ O ₂ in the processing methods C and D is 10 ppm or less.

FIG. 2 shows the MOS after the rinsing process of this embodiment.
The diode was prepared and the dielectric breakdown characteristics of the oxide film were evaluated. Examples A to C in which pure water containing no additive, pure water containing CO _{2 and} pure water containing HF were used for the rinse are also shown. HF / H ₂ O ₂
With the added pure water, good characteristics with minimum dielectric breakdown in a low electric field were obtained. It can be seen that the device characteristics are not deteriorated by the ion adsorption of the additive chemical on the surface of the semiconductor substrate. However, if the addition concentration of HF and H ₂ O ₂ in the C and D treatments exceeds 50 ppm, the dielectric breakdown in a low electric field increases, so 50 ppm or less is desirable.

In this embodiment, the bactericidal effect is the same as that of the HF-added pure water.

FIG. 3 shows the copper concentration on the surface of the semiconductor substrate after adding 1 ppb of copper to each pure water in the rinsing step of this embodiment and performing the rinsing process. It is understood that the HF / H ₂ O ₂ added pure water treatment D has the lowest copper concentration and is excellent in the effect of preventing the deposition of metal ions.

FIG. 4 shows the amount of deposited fine particles of 0.3 μm or more on the surface of the semiconductor substrate after the rinsing step of this embodiment.
It is understood that in the HF / H ₂ O ₂ added pure water treatment D, the amount of adhering fine particles is the smallest.

As described above, HF / H ₂ O ₂ added pure water has a function added to the rinse effect of pure water that has been used in the past, and most of the conventional pure water has been used. It is available for the process.

Next, a second embodiment of the present invention will be described. In the second embodiment, instead of H ₂ O ₂ , 10 to 10
It is used by adding 50 ppm of ozone to pure water. The obtained effect is exactly the same as that of the first embodiment.
Ozone is supplied by ozone water or by bubbling ozone. Since bubbling is performed in the cleaning layer, it is possible to supply ozone more stably by monitoring the concentration.

It should be noted that in the above embodiment, H 2 was added to pure water at room temperature.
Although F, H ₂ O ₂ or ozone was added, the treatment may be performed with the temperature of pure water at 50 to 80 ° C. In this case, HF,
If the concentration of H ₂ O ₂ or ozone is 5 to 50 ppm, the same effect as in the first and second embodiments can be obtained.

[0017]

As described above, the present invention is 10 to 5
By treating the semiconductor substrate after the chemical treatment with pure water to which 0 ppm hydrogen fluoride and 10 to 50 ppm hydrogen peroxide (or ozone) are added, in addition to the rinse effect of pure water, the device characteristics are deteriorated. In this way, it is possible to obtain excellent effects in suppressing oxide film growth, sterilization, preventing adhesion of fine particles, and preventing deposition of metal ions.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a natural oxide film pressure and a standing time for explaining an effect of an embodiment.

FIG. 2 is a diagram showing a relationship between a defective rate and an electric field for explaining the effect of the embodiment.

FIG. 3 is a diagram showing a relationship between a surface copper concentration and a treatment method for explaining the effect of the embodiment.

FIG. 4 is a diagram showing a relationship between the number of adhering trace particles and a treatment method for explaining the effect of the embodiment.

[Explanation of symbols]

A Additive-free pure water treatment B CO ₂ -added pure water treatment C HF-added pure water treatment D HF / H ₂ O ₂ -added pure water treatment

Claims (1)

[Claims] 1. A method of treating a semiconductor substrate, which comprises treating the semiconductor substrate with a chemical solution and then rinsing the semiconductor substrate with pure water.
A method for treating a semiconductor substrate, characterized in that hydrogen peroxide or ozone of ˜50 ppm is added.