Method for selective etching Si in the presence of silicon nitride, its composition and application thereof

Abstract

A method for selective etching Si in the presence of silicon nitride and an etching composition with high Si/Si3N4 etching selectivity are disclosed. Particularly, the method for selective etching Si in the presence of silicon nitride is to apply the etching composition with high Si/Si3N4 etching selectivity in the etching process, and the etching composition with high Si/Si3N4 etching selectivity comprises about 0.5 wt. % to about 10 wt. % of at least one quaternary ammonium compound, about 5 wt. % to about 55 wt. % of at least one primary amine, about 15 wt. % to about 80 wt. % of at least one polyol, and about 10 wt. % to about 35 wt. % water based on total weight of the etching composition.

Claims

1. A method for selective etching Si in the presence of silicon nitride, comprising: applying an etching composition in an etching process, wherein the etching composition comprises about 0.5 wt. % to about 10 wt. % of at least one quaternary ammonium compound, about 5 wt. % to about 55 wt. % of at least one primary amine, about 15 wt. % to about 80 wt. % of at least one polyol, and about 10 wt. % to about 35 wt. % water based on total weight of the etching composition.

2. The method of claim 1, wherein the etching composition has a Si/Si3N4 etching selectivity more than 5000/1.

3. The method of claim 1, wherein the quaternary ammonium compound has a structure of R.sub.1R.sub.2R.sub.3R.sub.4N.sup.+OH.sup.−, where R1, R2, R3 and R4 are C1-C4 linear chain alkyl groups, C1-C4 branched chain alkyl groups, C1-C4 linear alcohol or C1-C4 branched alcohol, respectively.

4. The method of claim 1, wherein the quaternary ammonium compound comprises tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide (ETMAH), tetraethylammonium hydroxide (TEAH), 2-hydroxyethyl trimethylammonium hydroxide or their mixture.

5. The method of claim 1, wherein the primary amine comprises 2-aminoethanol, 3-Aminopropan-1-ol, 4-Amino-1-butanol or their mixture.

6. The method of claim 1, wherein the polyol comprises ethane-1,2-diol, 1,2-propanediol, 1,3-propanediol or their mixture.

7. The method of claim 1, being applying in a nanoscale Si pattern etching process for fabricating semiconductors.

8. A nanoscale Si pattern etching process for fabricating semiconductors, comprising: applying an etching composition on a substrate to form a Si pattern having a gate width of 1-28 nm, wherein the etching composition comprises about 0.5 wt. % to about 10 wt. % of at least one quaternary ammonium compound, about 5 wt. % to about 55 wt. % of at least one primary amine, about 15 wt. % to about 80 wt. % of at least one polyol, and about 10 wt. % to about 35 wt. % water based on total weight of the etching composition.

9. The nanoscale Si pattern etching process of claim 8, wherein the substrate comprises a silicon nitride structure.

10. The nanoscale Si pattern etching process of claim 8, wherein the etching composition has a Si/Si3N4 etching selectivity more than 5000/1.

11. The nanoscale Si pattern etching process of claim 8, wherein the quaternary ammonium compound has a structure as shown in R.sub.1R.sub.2R.sub.3R.sub.4N.sup.+OH.sup.−, where R1, R2, R3 and R4 are C1-C4 linear chain alkyl groups, C1-C4 branched chain alkyl groups, C1-C4 linear alcohol or C1-C4 branched alcohol, respectively.

12. The nanoscale Si pattern etching process of claim 8, wherein the quaternary ammonium compound comprises tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide (ETMAH), tetraethylammonium hydroxide (TEAH), 2-hydroxyethyl trimethylammonium hydroxide or their mixture.

13. The nanoscale Si pattern etching process of claim 8, wherein the primary amine comprises 2-aminoethanol, 3-Aminopropan-1-ol, 4-Amino-1-butanol or their mixture.

14. The nanoscale Si pattern etching process of claim 8, wherein the polyol comprises ethane-1,2-diol, 1,2-propanediol, 1,3-propanediol or their mixture.

Description

EMBODIMENTS

[0015] In a first embodiment, the invention discloses a method for selective etching Si in the presence of silicon nitride, comprising applying an etching composition in an etching process, wherein the etching composition comprises about 0.5 wt. % to about 10 wt. % of at least one quaternary ammonium compound, about 5 wt. % to about 55 wt. % of at least one primary amine, about 15 wt. % to about 80 wt. % of at least one polyol, and about 10 wt. % to about 35 wt. % water based on total weight of the etching composition.

[0016] In one example of the first embodiment, the method is highly specific to attack Si and has a Si/Si3N4 etching selectivity more than 5000/1.

[0017] In one example of the first embodiment, the quaternary ammonium compound has a structure as shown in R.sub.1R.sub.2R.sub.3R.sub.4N.sup.+OH.sup.−, where R1, R2, R3 and R4 are C1-C4 linear chain alkyl groups, C1-C4 branched chain alkyl groups, C1-C4 linear alcohol or C1-C4 branched alcohol, respectively.

[0018] In one example of the first embodiment, the quaternary ammonium compound comprises tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide (ETMAH), tetraethylammonium hydroxide (TEAH), 2-hydroxyethyl trimethylammonium hydroxide or their mixture.

[0019] In one example of the first embodiment, the primary amine comprises 2-aminoethanol, 3-Aminopropan-1-ol, 4-Amino-1-butanol or their mixture.

[0020] In one example of the first embodiment, the polyol comprises ethane-1,2-diol, 1,2-propanediol, 1,3-propanediol or their mixture.

[0021] In one example of the first embodiment, the method is to apply in a nanoscale Si pattern etching process for fabricating semiconductors. Preferably, the nanoscale Si pattern has a gate width of 1-28 nm. More preferably, the nanoscale Si pattern has a gate width of 1-10 nm.

[0022] In a second embodiment, the invention provides an etching composition with Si/Si3N4 etching selectivity more than 5000/1. The etching composition with Si/Si3N4 etching selectivity more than 5000/1 comprises about 0.5 wt. % to about 10 wt. % of at least one quaternary ammonium compound, about 5 wt. % to about 55 wt. % of at least one primary amine, about 15 wt. % to about 80 wt. % of at least one polyol, and about 10 wt. % to about 35 wt. % water based on total weight of the etching composition.

[0023] In one example of the second embodiment, the quaternary ammonium compound has a structure as shown in R.sub.1R.sub.2R.sub.3R.sub.4N.sup.+OH.sup.−, where R1, R2, R3 and R4 are C1-C4 linear chain alkyl groups, C1-C4 branched chain alkyl groups, C1-C4 linear alcohol or C1-C4 branched alcohol, respectively.

[0024] In one example of the second embodiment, the quaternary ammonium compound comprises tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide (ETMAH), tetraethylammonium hydroxide (TEAH), 2-hydroxyethyl trimethylammonium hydroxide or their mixture.

[0025] In one example of the second embodiment, the primary amine comprises 2-aminoethanol, 3-Aminopropan-1-ol, 4-Amino-1-butanol or their mixture.

[0026] In one example of the second embodiment, the polyol comprises ethane-1,2-diol, 1,2-propanediol, 1,3-propanediol or their mixture.

[0027] In one example of the second embodiment, the etching composition with Si/Si3N4 etching selectivity more than 5000/1 is to apply in a nanoscale Si pattern etching process for fabricating semiconductors. Preferably, the nanoscale Si pattern has a gate width of 1-28 nm. More preferably, the nanoscale Si pattern has a gate width of 1-10 nm.

[0028] In a third embodiment, the invention discloses a nanoscale Si pattern etching process for fabricating semiconductors. The process comprises a step of applying an etching composition on a substrate to form a Si pattern having a gate width of 1-28 nm, wherein the etching composition comprises about 0.5 wt. % to about 10 wt. % of at least one quaternary ammonium compound, about 5 wt. % to about 55 wt. % of at least one primary amine, about 15 wt. % to about 80 wt. % of at least one polyol, and about 10 wt. % to about 35 wt. % water based on total weight of the etching composition.

[0029] Preferably, the nanoscale Si pattern has a gate width of 1-28 nm. More preferably, the nanoscale Si pattern has a gate width of 1-10 nm.

[0030] In one example of the third embodiment, the substrate comprises a silicon nitride structure, for example, the substrate comprises a silicon nitride film or a silicon nitride layer on its surfaces.

[0031] In one example of the third embodiment, the etching composition has a Si/Si3N4 etching selectivity more than 5000/1.

[0032] In one example of the third embodiment, the quaternary ammonium compound has a structure as shown in R.sub.1R.sub.2R.sub.3R.sub.4N.sup.+OH.sup.−, where R1, R2, R3 and R4 are C1-C4 linear chain alkyl groups, C1-C4 branched chain alkyl groups, C1-C4 linear alcohol or C1-C4 branched alcohol, respectively.

[0033] In one example of the third embodiment, the quaternary ammonium compound comprises tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide (ETMAH), tetraethylammonium hydroxide (TEAH), 2-hydroxyethyl trimethylammonium hydroxide or their mixture.

[0034] In one example of the third embodiment, the primary amine comprises 2-aminoethanol, 3-Aminopropan-1-ol, 4-Amino-1-butanol or their mixture.

[0035] In one example of the third embodiment, the polyol comprises ethane-1,2-diol, 1,2-propanediol, 1,3-propanediol or their mixture.

[0036] Following working examples are provided to prove the technical effects of the invention.

[0037] Measurement of Etching Rate of the Etching Composition and Si/Si.sub.3N.sub.4 Etching Selectivity

[0038] The measurement of etching rate of the etching composition is performed at 60° C. Testing specimen is a wafer surface coating an amorphous silicon film and a wafer surface coating a Si.sub.3N.sub.4 film, respectively. The amorphous silicon film has a thickness of 2000 Å (Angstrom), and the Si.sub.3N.sub.4 film has a thickness of 600 Å (Angstrom). Measure the thickness of the amorphous silicon film and Si.sub.3N.sub.4 film before etching process by Ellipsometer and obtain initial thickness value X Å, respectively. Then, completely immerse the testing specimen into the silicone etchant at 60° C. After T (1˜60) minutes, remove the testing specimen from the silicone etchant and wash the testing specimen with pure water until no residual silicone etchant on the surface. Measure the thickness of the amorphous silicon film and Si.sub.3N.sub.4 film again and obtain a thickness value Y Å. The etching rate of the silicone etchant is calculated by the following equation.

The etching rate(Å/min)=(XÅ−YÅ)/T(Time(min))

[0039] According to the aforementioned measurement and equation, the etching rate of amorphous silicon (Si) and Si.sub.3N.sub.4 are obtained. Si/Si.sub.3N.sub.4 etching selectivity of the silicon etchant is calculated by the etching rate of amorphous silicon (Si) divided by the etching rate of Si.sub.3N.sub.4.

[0040] Eleven etching compositions are evaluated their performance. The etching compositions, the etching rate of amorphous silicon (Si), the etching rate of Si.sub.3N.sub.4 and Si/Si.sub.3N.sub.4 etching selectivity are list in TABLE 1. The etching compositions used in examples 1-6 are formulated according to the present invention. The etching compositions used in examples 7-11 are formulated according to traditional technology.

TABLE-US-00001 TABLE 1 Quaternary Etching rate Etching rate Si/Si.sub.3N.sub.4 ammonium of Si of Si.sub.3N.sub.4 etching Example hydroxide Amine Polyol (Å/min) (Å/min) selectivity 1 TMAH.sup.1 1.5% MEA.sup.4 10% EG.sup.5 70% 305 0.02 15250 2 TMAH 1.5%  MEA 40% EG 30% 326 0.04 8150 3 ETMAH.sup.2 2.0%  MEA 10% EG 70% 359 0.03 11967 4 ETMAH 3.0%  MEA 40% EG 30% 422 0.06 7033 5 Choline OH.sup.3 5%  MEA 10% EG 70% 435 0.07 6214 6 Choline OH 8%  MEA 40% EG 30% 558 0.1 5580 7 TMAH 1.5% 1022 1.9 538 8 TMAH 1.5%  MEA 50% 381 0.19 2005 9 TMAH 1.5% EG 50% 376 0.17 2212 10 ETMAH 1.8% 1164 2.1 554 11 Choline OH 5%  MEA 20% EG 30% 527 0.24 2196 1. TMAH: Tetramethylammonium hydroxide 2. ETMAH: Ethyltrimethylammonium hydroxide 3. Choline OH: 2-Hydroxyethyltrimethylammonium hydroxide 4. MEA: Monoehtanolamine 5. EG: Ethylene glycol

[0041] According to TABLE 1, obviously, the etching compositions prepared according to the present invention have Si/Si.sub.3N.sub.4 etching selectivity more than 5000/1, and are suitable for applying in a nanoscale Si pattern etching process for fabricating semiconductors. Preferably, the invented method for selective etching Si in the presence silicon nitride is used in fabrication of nanoscale Si patterns having a gate width of 1-28 nm. Therefore, the present invention has an unexpectable effect when compared to the traditional or known etching compositions.

[0042] Obviously, many modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the present invention can be practiced otherwise than as specifically described herein. Although specific embodiments have been illustrated and described herein, it is obvious to those skilled in the art that many modifications of the present invention may be made without departing from what is intended to be limited solely by the appended claims.