JP5633838B2 - A method for processing a semiconductor substrate and a method for manufacturing a semiconductor device. - Google Patents

Description

The present invention relates to a method for processing a semiconductor substrate and a method for manufacturing a semiconductor device using a cyan (CN) -containing cleaning solution capable of removing contamination due to metal or the like on the surface of the substrate such as a semiconductor.

As cyan (CN) -containing cleaning liquid capable of removing contamination of the substrate surface such as semiconductor by metal, etc., hydrogen cyanide (HCN) is already pure water or ultrapure water, alcohol solvent, ketone solvent, nitrile solvent. , Dissolved in an aromatic hydrocarbon solvent, carbon tetrachloride, ether solvent, aliphatic alkane solvent, or a mixed solvent thereof, and further diluted to a predetermined concentration, and with an aqueous ammonia solution, the hydrogen ion concentration in the solution It is found that the removal effect of contaminant metals such as copper (Cu) on the surface of a substrate such as a semiconductor can be remarkably improved by adjusting the index, so-called pH value, in the range of 5 to 12, preferably 6 to 9. (Patent Document 1).

In addition, in order to reduce the environmental load, the present inventor diluted the hydrogen cyanide (HCN) in the cleaning solution to 0.1 mM (mmol), that is, about 2.7 ppm, and washed it at room temperature of pH 10 and 25 ° C. before cleaning. The surface concentration of Cu after washing is removed from the Cu surface concentration of 10 ¹³ to 10 ¹⁴ atoms / cm ² to below the detection limit of copper (˜3 × 10 ⁹ atoms / cm ² ) using a total reflection X-ray fluorescence spectrometer. It was shown that it can be done (for example, nonpatent literature 1).

Japanese Patent Laid-Open No. 2005-39198

Proceedings of the 69th JSAP Autumn Meeting in 2008, No.2, p.692, 3a-CD-4 Contamination on SiO2 surface by extremely low concentration defect extinction semiconductor cleaning solution Removal of Cu (authors: Yuko Higashi, Masao Takahashi, Yoshio Iwasa, Hikari Kobayashi)

The present invention provides a method for processing a semiconductor substrate and a method for manufacturing a semiconductor device with a very low concentration cyan (CN) -containing solution that conforms to an environmental standard value of cyan (CN) concentration.

The present invention is a semiconductor substrate processing method for heating a cyan-containing solution having a cyan (CN) content of 1 ppm or more and less than 100 ppm and cleaning the semiconductor substrate at a temperature of at least 30 to 40 ° C. It is possible to remove contamination of the substrate surface such as a semiconductor by a metal or the like in a practical short time.

The present invention is a cyan-containing solution in which the solution in the cleaning treatment process is 1 ppm or more and less than 100 ppm , adjusted to a hydrogen ion concentration index (pH) of 9 to 14, and the solution temperature is at least 30 to 40 ° C. It is possible to remove the contamination of the substrate surface such as a semiconductor by a metal or the like by a practical short time treatment of several minutes to 10 minutes.

The present invention further includes a step of cleaning a semiconductor substrate at a temperature of at least 30 to 40 ° C. by heating a cyan-containing solution having a cyan (CN) content of 1 ppm or more and less than 100 ppm and at least 10 ppm to 1 ppm. Thus, it is possible to remove contamination of the substrate surface such as a semiconductor by a metal or the like with a practical short time treatment.

Furthermore, the solution of the cleaning process in the manufacturing method of the semiconductor device, cyan-containing solution cyan (CN) including chromatic weight of less than 100ppm than 1 ppm, is adjusted to a hydrogen ion concentration exponent (pH) 9 to 14, a solution When the temperature is at least 30 to 40 ° C., it is possible to remove contamination of the surface of the substrate such as a semiconductor by a metal or the like with a practical short time treatment of several minutes to 10 minutes.

Note that the cyanide (CN) -containing solution used in the present invention includes hydrogen cyanide (HCN) in pure water or ultrapure water, alcohol solvent and ketone solvent, nitrile solvent, aromatic hydrocarbon solvent, carbon tetrachloride, ether. It is dissolved in at least one solvent selected from a system solvent, an aliphatic alkane solvent, or a mixed solvent thereof, and further diluted to a predetermined concentration. It is suitable to adjust and use in the range of 9-14, preferably pH 6-11.

According to the present invention, in the process of manufacturing a semiconductor device or an electronic device using a semiconductor wafer, metal contamination such as copper of the semiconductor wafer is removed and the surface level of the semiconductor wafer surface caused by dangling bonds or the like. A significant effect can be exhibited in reducing the position.

Further, according to the present invention, a cyan-containing solution having a cyan (CN) content of 1 ppm or more and less than 100 ppm and at least 10 ppm to 1 ppm is heated with a cyan-containing solution having a hydrogen ion concentration index (pH) of 9 to 14 to obtain a solution. By cleaning the semiconductor substrate at a temperature of at least 30 to 40 ° C., for example, a surface copper concentration of 10 ¹² to 10 ¹³ atoms / cm ² is reduced to an order of 10 ⁹ atoms / cm ^2. As a result, it is clear that the solution is removed, and a high cleaning effect can be achieved, and since the cyan (CN) content in the solution after the cleaning treatment is small, the solution is adsorbed on, for example, an ion exchange resin. It is sufficiently possible to perform processing by such means as to meet the environmental standard value of cyan (CN) concentration, and the waste liquid processing burden is reduced.

It is a relationship characteristic figure of immersion (cleaning) time and surface copper concentration. Example 1

The Si wafer formed with the thermal oxide film is immersed in a cupric chloride (CuCl ₂ ) aqueous solution and intentionally contaminated with copper having a surface copper concentration of 10 ¹² to 10 ¹³ atoms / cm ^2. (CN) Immersion cleaning was performed with an HCN aqueous solution (cleaning solution) having a concentration of 1 ppm and pH 10.

In order to stabilize the pH in the preparation of the cleaning liquid, it is desirable to adjust the pH value of the cleaning liquid itself to a desired value by mixing a solution containing ammonia, choline, TMAH, NaOH, KOH and the like.

FIG. 1 shows the results of immersion (cleaning treatment) times when the above-mentioned copper-contaminated wafer is immersed in an aqueous HCN solution having a pH of 10 and a cyan (CN) concentration of 1 ppm at 25 ° C. and 35 ° C. It is a characteristic view which shows the decreasing degree of surface copper concentration. From these results, it can be seen that there are different phenomena represented by the reaction process (process 1 and process 2) at 25 ° C. and 35 ° C., and in particular, the temperature dependence of the removal rate is almost recognized in the reaction process 1. Although it is not (small), the reaction process 2 is remarkably large, and by raising the solution temperature by only 10 ° C. from room temperature, the reaction process 2 having a large temperature dependence works effectively, and the copper contamination is almost completely eliminated. It turns out that it can be removed.

From this example, the surface copper concentration of the wafer before cleaning is 10 ¹² by heating the solution with a very low concentration HCN aqueous solution (cleaning solution) of 1 ppm and pH 10 to 35 ° C., which is slightly higher than room temperature. What was contaminated by -10 ¹³ atoms / cm ² is removed after the immersion cleaning to below the copper detection limit (-3 × 10 ⁹ atoms / cm ² ) by the total reflection X-ray fluorescence spectrometer. I was able to confirm that.

By using an aqueous HCN solution, cyanide ions (CN ⁻ ) react with copper on the SiO ₂ surface to form [Cu (CN) ₂ ] ⁻ to remove contaminated copper. [Cu (CN) ₂ ] ⁻ reacts with CN ⁻ ions in the aqueous HCN solution, and stably exists as [Cu (CN) ₄ ] ^{3− at} pH 10. The ability to form complex ions of CN ⁻ ions is extremely high, and even in an extremely low concentration HCN aqueous solution, CN ⁻ ions can react effectively to remove contaminating copper.

If the temperature of the cleaning solution is increased excessively from 50 ° C., the vaporization (evaporation) of cyan (CN) in the solution occurs and the cleaning effect is reduced, but according to experience, the extreme of cyan (CN) concentration of 1 ppm order By adjusting the pH to 9 to 12 at a low concentration, the reaction temperature 2 clearly shown in FIG. 1 is maintained by maintaining the solution temperature at an appropriate temperature in the range of 50 ° C. or lower, preferably 30 ° C. to 40 ° C. 2 Thus, it is possible to effectively obtain the cleaning effect of removing contaminating metals with such a solution by suppressing the evaporation of cyan (CN).

The present invention removes metal contamination such as copper of the semiconductor wafer in the process of manufacturing a semiconductor device or an electronic device using the semiconductor wafer, and surface level due to dangling bonds or the like on the surface of the semiconductor wafer. In the process of manufacturing a semiconductor device or an electronic device, it is effective to perform the cleaning treatment according to the present invention before, during, or after the manufacturing process. Directly, after chemical mechanical polishing (CMP) for forming a copper wiring by, for example, a damascene method, it can be used for removal of residual fine grains and shaping of an end such as chamfering.

The present invention is not limited to the cleaning process for semiconductor wafers, but can also be used for the cleaning process for removing the surface contamination of solid materials, or the cleaning process for removing the surface contamination of production equipment and equipment.

1 Reaction process with low temperature dependence 1
2 Temperature-dependent reaction process 2

Claims (5)

A method for treating a semiconductor substrate, comprising: heating a cyan-containing solution having a cyan (CN) content of 1 ppm or more and less than 100 ppm , and washing the semiconductor substrate at a temperature of 30 ° C. to 40 ° C.   2. The method of processing a semiconductor substrate according to claim 1, wherein the cyan-containing solution has a hydrogen ion concentration index (pH) of 9 to 14. The cyan-containing solution is pure hydrogen or ultrapure water, alcohol solvent and ketone solvent, nitrile solvent, aromatic hydrocarbon solvent, carbon tetrachloride, ether solvent, aliphatic alkane solvent, or these. The method for treating a semiconductor substrate according to claim 1, wherein the semiconductor substrate is prepared by dissolving at least one selected from the mixed solvents. A method for manufacturing a semiconductor device, comprising: heating a cyan-containing solution having a CN content of 1 ppm or more and less than 100 ppm , and cleaning the semiconductor substrate at a temperature of 30 ° C. to 40 ° C. 5. The method of manufacturing a semiconductor device according to claim 4, wherein the cyan-containing solution has a hydrogen ion concentration index (pH) of 9 to 14.

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