JP2002025965A - Cleaning solution for semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning solution for cleaning a semiconductor substrate with a metal film of tungsten or the like formed on its surface. SOLUTION: A cleaning solution containing hydrogen peroxide and amine having cyclohexane rings that serves as a skeleton is used to clean a semiconductor substrate with a metal film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning solution for a semiconductor substrate having a metal film on the surface.

[0002]

2. Description of the Related Art In recent years, the demand for higher speed and higher performance in semiconductor devices has led to lower resistance of materials, and the use of metal materials has been increasing. Further, with the progress of multi-layer wiring and miniaturization of elements, more precise and precise processing is required, and the margin of processing dimensions is becoming smaller. As the degree of integration of the semiconductor device increases, it becomes essential to improve the yield by improving the cleanliness of the surface of the semiconductor device without organic matter, foreign matter and metal contamination. Therefore, a more precise cleaning method is required.

Conventionally, semiconductor device cleaning includes SPM (sulfuric acid-hydrogen peroxide) cleaning for removing organic substances or resist, APM (SC-1, ammonia-hydrogen peroxide) cleaning for removing foreign substances, and contaminant metal removal. HPM (S
A so-called RCA cleaning method comprising a combination of (C-2, hydrochloric acid-hydrogen peroxide) cleaning is used, and the cleaning effect has been improved by the ultra-purification of a chemical solution and the combined use of physical cleaning power such as megasonic. Also, a cleaning method using ozone water or functional water in place of hydrogen peroxide, and cleaning for the purpose of simultaneously removing foreign substances and contaminated metals by adding a chelating agent to the cleaning liquid during APM cleaning. Cleaning techniques have also been improved, including the development of methods.

However, among these cleaning methods, APM cleaning is effective when the surface of the semiconductor substrate is bare silicon or a silicon oxide film, but is applied to a metal film such as a tungsten film, a WSix (tungsten silicide) film, or a TiW (titan) film. In some cases, there is a problem in that the metal is greatly eroded, so that the processing accuracy is reduced and the resistance value is fluctuated.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art, and to provide a cleaning liquid which does not corrode or erode metals on a semiconductor substrate, and provides a clean and high-precision surface. It is to provide a cleaning method.

[0006]

Means for Solving the Problems The present inventors have conducted extensive studies on cleaning a semiconductor substrate having a metal film, and as a result, have found that using a cleaning solution comprising hydrogen peroxide and an amine having a cyclohexane ring as a skeleton allows the metal film to be cleaned. The present invention has been found that erosion of a semiconductor can be prevented and a clean semiconductor surface can be obtained.

That is, the present invention relates to a cleaning solution for a semiconductor substrate having a metal film containing hydrogen peroxide and an amine having a skeleton of a cyclohexane ring. Further, a complexing agent may be added to the washing liquid.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The metal film of the present invention is tungsten, copper, aluminum, cobalt, titanium or tantalum, or a compound thereof with silicon, nitrogen or oxygen, and may be an alloy containing a plurality of these. Among them, it is particularly effective for corrosion prevention of a tungsten metal film having a corrosion area under an alkaline solution having a high oxidation-reduction potential.

In the cleaning liquid of the present invention, ozone water can be used instead of hydrogen peroxide. In addition, the amine having a cyclohexane ring in the skeleton used in the cleaning solution of the present invention,
N-methylcyclohexylamine, 1,2-cyclohexanediamine, 2-aminocyclohexanol and the like can be mentioned, and a combination of several kinds of these may be used. this house,
In particular, 2-aminocyclohexanol has a large cleaning effect while suppressing metal erosion.

The complexing agent used in the washing solution of the present invention is a phosphoric acid compound or a phosphonic acid chelating agent. Specifically, methyl diphosphonic acid, aminotris (methylene phosphonic acid), ethylidene diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, 1-hydroxypropylidene-1,1-diphosphonic acid, 1- Hydroxybutylidene-1,1-diphosphonic acid, ethylaminobis (methylenephosphonic acid), 1,2-propylenediaminetetra (methylenephosphonic acid) "PDTP", dodecylaminobis (methylenephosphonic acid), nitrilotris (methylenephosphonic acid) Acid), ethylenediaminebis (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), hexenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) "DTPP", cyclohexanediaminetetra (methylenephosphonic acid) Acid), triethylenetetraminehexa (methylenephosphonic acid), tetraethylenepentaminehepta (methylenephosphonic acid), glycol etherdiaminetetra (methylenephosphonic acid), and oxidized forms and salts thereof. Among them, especially PDT
P and DTPP are preferred.

In the present invention, when a cleaning solution comprising hydrogen peroxide and an amine having a cyclohexane ring as a skeleton is used, hydrogen peroxide is used in an amount of 0.01 to 10% by weight, preferably 0.1 to 10% by weight.
1 to 5% by weight, 0.01 to 3% by weight, preferably 0.1 to 2% by weight, amine having a skeleton of a cyclohexane ring, and the balance being water. When the content of hydrogen peroxide is 0.01% by weight or less, the effect of removing foreign substances is reduced, and when the content is 10% by weight or more, metal erosion increases. The pH of the washing solution is 8-12, preferably 9-1.
0. When the pH is 8 or less, the effect of removing foreign substances decreases,
If it is more than 12, the amount of the chemical used increases and it is not economical. Also,
By adding 1 ppb to 1% by weight, preferably 10 to 1000 ppm of a complexing agent to the cleaning liquid, the corrosion prevention effect of the metal film is further increased. If the complexing agent is 1 ppb or less, there is no effect, and even if 1% or more is added, a significant improvement in the effect cannot be expected. The washing temperature is 20 to 90 ° C, preferably 40 to 90 ° C.
60 ° C. If it is lower than 20 ° C., the effect of removing foreign substances is reduced, and if it is higher than 90 ° C., erosion of the metal film is increased. Further, a physical force such as megasonic may be added for more effective cleaning.

[0012]

EXAMPLES Examples 1 to 6 and Comparative Examples 1 to 4 Tungsten pieces were immersed in various chemicals, and the etching rate was determined from the amount of tungsten test pieces eluted.
In Examples 1 to 3, an amine having a cyclohexane ring in the skeleton was mixed with 500 ml of 5% by weight of hydrogen peroxide to obtain 5% by weight.
Washing was performed at 0 ° C. In Examples 4 to 6, washing was performed similarly by adding 1000 ppm of PDTP as a complexing agent. In Comparative Examples 1 to 4, 5% by weight of hydrogen peroxide 500
Ammonia water or an amine having no cyclohexane ring was mixed with the resulting solution, and washing was performed in the same manner. Table 1 shows the etching rates of tungsten in the above cleaning.

[0013]

[Table 1]

Example 7 10 ⁶ particles / mm ² of silica particles having an average particle diameter of 0.2 μm were adhered to a tungsten piece, and were subjected to megasonic cleaning with the chemicals used in Examples 1 to 6. After washing, as observed by a scanning electron microscope and a particle counter, no silica particles were detected. At this time, the etching rates of tungsten were respectively equal to the values of Examples 1 to 6 shown in Table 1.

[0015]

According to the present invention, when cleaning a semiconductor substrate having a metal film, the metal film can be precisely cleaned without greatly eroding the metal film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23G 5/024 C23G 5/024 5/036 5/036 H01L 21/306 H01L 21 / 306F (72) Invention Person Tomoyuki Higashi 2-5-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4H003 BA12 DA15 DB01 EA20 EB13 EB24 EE04 FA07 FA15 FA21 4K053 PA06 PA09 PA10 QA04 RA13 RA40 RA52 RA59 RA62 5F043 AA40 BB30 GG10

Claims (5)

[Claims] 1. A cleaning solution for a semiconductor substrate having a metal film containing a hydrogen peroxide and an amine having a cyclohexane ring as a skeleton. 2. The cleaning solution for a semiconductor substrate according to claim 1, further comprising a complexing agent. 3. The cleaning solution according to claim 1, wherein the amine having a skeleton of a cyclohexane ring is N-methylcyclohexylamine, 1,2-cyclohexanediamine, or 2-aminocyclohexanol. 4. The cleaning solution according to claim 1, wherein the metal film is tungsten, copper, aluminum, cobalt, titanium, or tantalum, or a compound thereof with silicon, nitrogen, or oxygen. 5. A method for cleaning a semiconductor substrate having a metal film, wherein the substrate surface is cleaned while preventing erosion of the metal film by using a cleaning solution containing hydrogen peroxide and an amine having a cyclohexane ring as a skeleton.