KR20100137746A - Manufacturing method of selective etching of the etching solution with (si3n4) and (tin),based on silicon oxide - Google Patents

Abstract

PURPOSE: An etchant solution containing HF, NH4F, deionized water and poly(acrylic acid) additive is provided to increase etching selectivity and to selectively control an etching rate. CONSTITUTION: An etchant solution comprises HF 10 weight% ~25 weight%, NH4F 15 weight% ~30 weight%, and deionized water and additive. The etchant solution has a selective etching rate for a silicon nitride layer and a titanium nitride layer based on a silicon oxide layer. The etchant solution comprises poly(acrylic acid) additives. The additive is in [-(C3H4O2)-]n range and is one molecular weight(MW) of 1800g/mole and 450,000g/mole.

Description

Manufacture method of selective etching of the etching solution with (Si3N4) and (TiN), Based on silicon oxide}

According to the present invention, the wet etching solution to which poly acrylic acid is added is used for silicon oxide film based on about 8000 kPa ~ 10000 kPa / min, the titanium nitride film etching rate is 1 kW / min or less, and the silicon nitride film etching rate is about 40 kPa ~ Controllable to a level of 60 μs / min, selective wet type with an etching selectivity of about 180: 1 to 200: 1 for silicon nitride and about 8000: 1 to 10000: 1 for titanium nitride It relates to an etching solution.

In the process of manufacturing a semiconductor device, a silicon oxide film is used for electrical insulation between conductive layers.

This silicon oxide film is formed by a deposition or growth method and is removed by a dry or wet method.

Dilute hydrofluoric acid (DHF) and buffered etch solution (BOE) are widely used as wet etchants for wet etching silicon oxide films. The BOE solution consists of a mixture of hydrogen fluoride (HF), ammonium fluoride (NH 4 F) and deionized water.

The etching type of the oxide layer may be classified into selective etching, full etching, and undercut. The most important thing in any etching process is the selectivity of the etching solution. Therefore, the etching solution needs to have a high selectivity.

The etching solution not only affects the material to be removed, but can also attack the mask or PR and the substrate. The selectivity of the etch solution is regarded as the ability to keep the mask and substrate material intact while removing only the etch material. The selectivity is measured as the ratio between the different etch rates of the etch solution to the different materials. It is necessary to have a high selectivity relative to both the mask and the substrate, i.e. the etch rate for the film to be etched must be significantly higher than the etch rate for both the mask, substrate and other nearby or adjacent materials. The etching of silicon oxides such as phosphorus-doped silicon glass (PSG), boron and indoping silicon glass (BPSG), boron-doped silicon glass (BSG) and silicon oxynitride has been conventionally etched using HF aqueous solution.

Such formulations effectively etch the silicon oxides, but tend to overetch the surrounding structures formed of materials such as nitrides, metals, silicon and silicides. A long-term problem with the conventional wet oxide etching solution is low selectivity. Such etching solutions may attack the surrounding structure to yield an undesired or unacceptable degree of etching, or may cause adhesion loss and expansion to the substrate to which the photoresist is applied to some photoresist. This decline in selection became more unacceptable as the minimum line width continued to decrease.

In particular, there is a need in the semiconductor industry for the use of such compositions for the removal of silicon nitride and titanium nitride, such as other materials that come into contact with higher selective wet etching compositions during the etching process.

The present invention relates to a wet etching solution manufacturing method capable of increasing the etching selectivity and selectively controlling the etching rate by using a poly acrylic acid (PAA) series as an additive as an additive.

Etching solution according to the present invention is composed of HF, NH4F, deionized water and PAA (Poly Acrylic Acid) series, based on silicon oxide film, about 180: 1 to 200: 1 for silicon nitride film, about 8000: 1 for titanium nitride film Efficient etching is possible by having a selective etching ratio of ˜10000: 1. In addition, the silicon oxide film may be selectively etched in the manufacturing process due to the high integration of the device and the miniaturization of the pattern size during the semiconductor process. Can be used.

In the silicon oxide film, silicon nitride film, and titanium nitride film etching method according to the present invention, a silicon oxide film, a silicon nitride film, and a titanium nitride film formed on a wafer are etched using a wet etching solution containing additives, and a BOE solution is used as a wet etchant. .

In particular, the present invention has a function to selectively control the etching rate of the silicon oxide film reference, silicon nitride film, and titanium nitride film by adjusting the composition and concentration of the poly acrylic acid (PAA) series as an additive.

That is, based on silicon oxide film about 8000Å ~ 10000Å / min, titanium nitride etch rate is less than 1Å / min, silicon nitride etch rate can be controlled up to about 40Å ~ 60Å / min, and about 180: 1 ~ 200: 1 for silicon nitride film , Selective wet etching solution characterized in that it has an etching selectivity of about 8000: 1 to 10000: 1 relative to the titanium nitride film.

In the present invention, after fixing the HF and NH4F to a specific concentration based on the above basic evaluation results, the composition of the additive is changed more finely to control the etching rate.

In the following, specific examples of preparing an etching solution according to the present invention will be described.

It is present in the amount of 10% to 25% by weight of HF and 15% to 25% by weight of NH4F, and consists of an etching solution to check the etching rate and the etching selectivity after mixing deionized water and additives.

Etchant HF NH4F Poly Acrylic Acid (MW = 450,000) Poly Acrylic Acid (MW = 1,800) Example 1 22 20 0 2.0 Example 2 22 20 0 5.0 Example 3 17 25 0 0.1 Example 4 17 25 0 1.0 Example 5 17 25 0 2.0 Example 6 22 20 0.01 0 Example 7 22 20 0.05 0 8 25 20 0.01 9 25 20 0.05 10 25 17 1.0 11 25 17 2.0 Comparative Example 1 25 20 0 0 Comparative Example 2 22 20 0 0 Comparative Example 3 22 20 0.1 0 Comparative Example 4 22 20 0 0.5 Comparative Example 5 22 20 0 1.0 Comparative Example 6 22 20 0 6.0 Comparative Example 7 25 17 0 0 Comparative Example 8 17 25 0 0 Comparative Example 9 17 25 0 0.01 Comparative Example 10 17 25 0 3.0 10 30 30 15

Etch Rate (Å / min) Etch selectivity PE-TEOS Nitride TiN PE-TEOS: Nitride PE-TEOS: TiN Example 1 10048.9 50.8 One 198: 1 10048.9: 1 Example 2 10093.8 51.2 One 197: 1 10093.8: 1 Example 3 8626.0 47.1 One 183: 1 8626.0: 1 Example 4 8323.4 44.6 One 187: 1 8323.4: 1 Example 5 8343.8 42.5 One 196: 1 8343.8: 1 Example 6 10002.5 55.8 One 179: 1 10002.5: 1 Example 7 10078.9 53.2 One 189: 1 10078.9: 1 8 10132.8 57.4 One 177: 1 10132.8: 1 9 10136.5 56.2 One 180: 1 10136.5: 1 10 9921.19 55.2 One 180: 1 9921.19: 1 11 9776.38 54.3 One 180: 1 9776.38: 1 One Comparative Example 1 11667.40 152.28 5.92 77: 1 1970: 1 Comparative Example 2 9921.19 135.79 7.52 73: 1 1319: 1 Comparative Example 3 Additive precipitation phenomenon Comparative Example 4 9954.68 124.63 0 79: 1 9954: 68 Comparative Example 5 10052.4 120.65 0 83: 1 10052: 1 Comparative Example 6 Additive precipitation phenomenon Comparative Example 7 12492.88 191.35 12.5 65: 1 999: 1 Comparative Example 8 8542.55 113.56 6.92 75: 1 1234: 1 Comparative Example 9 8214.61 112.10 5.96 73: 1 1378: 1 Comparative Example 10 Additive precipitation phenomenon

Conclusion to the Examples

In the Example, the etching solution was added to the PAA series to evaluate the etching rate using the following evaluation method.

Evaluation of etch rate per minute of silicon oxide film: 80 ml of 100 ml beaker was filled with an etching solution, and then the temperature was controlled at 25 ° C., followed by etching of the film of Nitride (Si3N4), PE-TEOS, TiN and drying with nitrogen gas. Å / min) was measured using a Nano Spec facility. The etching rate of silicon oxide film is about 8200Å ~ 10000Å / min, the silicon nitride film is about 40Å ~ 60Å / min and the titanium nitride film is about 1Å / min or less. Selective etching ratios of about 180: 1 to 200: 1 for the nitride film and about 8000: 1 to 10,000 for the titanium nitride film are shown in the examples.

If the HF content is less than 10% by weight, the etching rate (Å / min) of the silicon oxide film is too small. If the HF content is more than 25% by weight, the etching rate (Å / min) of the silicon nitride film is too large compared to that of the silicon oxide film. The selectivity between silicon nitride films becomes too low.

In addition, when the NH4F content is less than 15% by weight, the etching rate of the silicon oxide film and the silicon nitride film is excessively small, and when the NH4F content is more than 25% by weight, the etching rate of the silicon oxide film is excessively higher than that of the silicon nitride film. It is lowered, and the desired selection ratio cannot be obtained.

At 10% to 25% by weight of HF and 15% to 30% by weight of NH4F, the content of PAA (MW = 450,000) additives is at least 0.1% by weight and the content of PAA (MW = 1,800) additives is at least 6.0% by weight in the etching solution. Additive precipitation may occur and may also cause contamination of the wafer surface after etching.

At 10 wt% to 25 wt% of HF and 15 wt% to 30 wt% of NH4F, the content of PAA (MW = 1,800) additives of 6.0 wt% or more may cause additive precipitation in the etching solution, and the wafer surface after etching This can cause contamination problems.

Claims (5)

An etching solution having a selective etching ratio with respect to the silicon nitride film and the titanium nitride film based on the silicon oxide film, which is present in an amount of 10% to 25% by weight of HF and 15% to 30% by weight of NH4F, and mixed with deionized water and additives. The etching solution of claim 1, wherein the etching solution has a selective etching ratio with respect to the silicon nitride film and the titanium nitride film based on a silicon oxide film selected by mixing a poly acrylic acid (PAA) series as an additive. The method of claim 2, wherein the PAA-based additive is in the range of [-(C3H4O2)-] n, and the molecular weight (MW) is selected from 1800 g / mole and 450,000 g / mole to selectively etch the silicon oxide film, the silicon nitride film and the titanium nitride film. Etch solution with ratio [4] The etching solution of claim 3, wherein the PAA (MW = 450,000) additive contains 0.01 wt% to 0.1 wt% of the silicon oxide film and the selective etching ratio of the silicon nitride film and the titanium nitride film. [4] The etching solution of claim 3, wherein the PAA (MW = 1,800) additive contains 0.01 wt% to 6.0 wt% of the silicon oxide film and the selective etching ratio with respect to the silicon nitride film and the titanium nitride film.