High performance selective etching solution for silicon in silicon germanium / silicon stacks

Abstract

The application provides a high-performance selective etching solution for silicon in a silicon germanium / silicon stack, which comprises quaternary ammonium hydroxide, alkanolamine, a SiGe inhibitor and water. The high-performance and high-selectivity etching composition provided by the application can effectively maintain the etching of silicon while preventing the etching of silicon germanium, and the silicon / silicon germanium selectivity is greater than 20; when a furan ring compound and a polyamine compound are used in a certain proportion, the silicon / silicon germanium selectivity is as high as 345.

Description

Technical Field

[0001] This invention belongs to the field of electronic chemicals, and specifically relates to an etching solution suitable for selectively removing silicon from silicon-germanium / silicon stacks in microelectronic devices. Background Technology

[0002] To advance CMOS technology, we are exploring GAA MOSFETs (Gate-All-Around Metal-Oxide-Semiconductor Field-Effect Transistors) as a successor to FINFET (Fin Field-Effect Transistor) technology. The core of this transformation lies in exploring how to cleverly integrate SiGe or Ge materials, coupled with precise material removal techniques, to optimize the overall solution for short-channel effects. Specifically, the construction process of GAA MOSFETs involves the high-selectivity removal of Si or SiGe layers in a multilayer structure to achieve FINFET structure and patterning. These processes include the epitaxial deposition of alternating nanoscale Si sacrificial layers and SiGe channel layers, followed by a high-selectivity etching process to remove the Si sacrificial layers while appropriately controlling the erosion of the bulk substrate, leaving SiGe nanowire channels in the suspended trenches. Finally, a thin gate dielectric layer is deposited around the SiGe nanowires and trenches, and a metal overlay is applied to form the gate electrode of the GAA MOSFET.

[0003] In achieving this complex process, alkaline solution-based wet etching technology is favored due to its low cost, ease of operation, and low corrosiveness to silicon oxide. KOH and TMAH (tetramethylammonium hydroxide) are the two main etchants, each with its own advantages and disadvantages. While KOH is widely used, its reaction process may introduce potassium ions that affect device performance, and it also results in a relatively rough etched surface. In contrast, TMAH exhibits better compatibility with integrated circuit processes, but its etching rate is limited at high concentrations, and its etching selectivity for the Si sacrificial layer in Si / SiGe multilayer structures is not ideal, easily leading to damage to SiGe nanowires.

[0004] In view of this, there is an urgent need in the field for an etching composition designed to improve the etching process accuracy of the sacrificial Si layer while achieving highly selective protection of SiGe nanowires, in order to meet the stringent requirements for material processing accuracy in the advancement of GAA MOSFET technology. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a high-performance selective etching solution for silicon in a silicon-germanium / silicon stack, which etches the silicon-containing layer in the presence of the silicon-germanium layer. The etching solution comprises quaternary ammonium hydroxide, alkanolamine, SiGe inhibitor, and water.

[0006] Further, the quaternary ammonium hydroxide is R4NOH, where R is four identical or different aliphatic hydrocarbon groups or aromatic hydrocarbon groups, preferably one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, ethyltrimethylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, and most preferably tetramethylammonium hydroxide.

[0007] Further, the amount of the quaternary ammonium hydroxide is 0.3 - 50 wt%, preferably 1 - 40 wt%, more preferably 5 - 30 wt%, and most preferably 10 - 20 wt%.

[0008] Further, the alkanolamine is selected from one or more of monoethanolamine, diethanolamine, 2-(ethylamino)ethanol, 2-dibutylaminoethanol, N,N-diethylethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, cyclohexylamine diethanol, and preferably triethanolamine.

[0009] Further, the amount of the alkanolamine is 0.01 - 50 wt%, preferably 0.1 - 40 wt%, more preferably 0.5 - 30 wt%, and most preferably 1 - 20 wt%.

[0010] Further, the SiGe inhibitor is selected from one or more of quinoline compounds, polyamine compounds, furan ring compounds, and aromatic ether compounds.

[0011] Further, the amount of the SiGe inhibitor is 0.001 - 10 wt%, preferably 0.002 - 5 wt%, more preferably 0.005 - 2 wt%, and most preferably 0.01 - 0.5 wt%.

[0012] Further, the quinoline compounds are selected from one or more of 8-hydroxyquinoline, 2-amino-8-hydroxyquinoline, and 4-amino-2-methylquinoline.

[0013] Further, the polyamine compounds are selected from one or more of NH2(CH2) n NH2, polyvinylpyrrolidone, benzotriazole, hexamethylenetetramine, and preferably 1,6-hexanediamine, polyvinylpyrrolidone, benzotriazole, hexamethylenetetramine.

[0014] Further, in the NH2(CH2) n NH2, the value of n is 3 < n < 10; the viscosity K value of the polyvinylpyrrolidone is 8 - 100, preferably 10 - 40, and most preferably 12 - 20.

[0015] Further, the furan cyclic compound is selected from one or more of furan, dihydrofuran, tetrahydrofuran, 2-methylfuran, 3-methylfuran, 2,5-dimethylfuran, 2-ethylfuran, 2,2-dimethyltetrahydrofuran, 2-phenylfuran, 2-acetylfuran, and 5-methyl-2-acetylfuran; preferably one or more of furan, 2-ethylfuran, 2-phenylfuran, and 2-acetylfuran.

[0016] Further, the aromatic ether compound is selected from one or more of anisole, phenethyl ether, o-methoxyphenol, p-methoxyphenol, 2-methoxynaphthalene, phenoxybenzene, phenyl benzyl ether, 1,2-dimethoxybenzene, and 2,4-dimethoxybenzaldehyde; preferably one or more of anisole, p-methoxyphenol, and 2,4-dimethoxybenzaldehyde.

[0017] Furthermore, the etching solution may also contain one or more water-soluble organic solvents, which are one or more of propanol, isopropanol, propylene glycol, butanol, butyl diethylene glycol, cyclohexane, dimethylformamide, sulfolane, and dimethyl sulfoxide; preferably one or more of isopropanol, dimethylformamide, sulfolane, and dimethyl sulfoxide, more preferably isopropanol.

[0018] Furthermore, the amount of the water-soluble organic solvent used is 0.1-60 wt%, preferably 1-40 wt%, more preferably 2-30 wt%, and most preferably 5-20 wt%.

[0019] The present invention also provides a method for selectively etching silicon in a silicon-germanium / silicon stack using the above-mentioned etching solution, the steps of which are as follows:

[0020] The etching solution comes into contact with the microelectronic device containing the silicon-germanium / silicon stack at a temperature of 10°C-100°C to complete the silicon layer etching.

[0021] Furthermore, the contact time is <24h, preferably 1-60min.

[0022] Furthermore, the contact temperature is preferably 20-80℃, more preferably 25-60℃.

[0023] Furthermore, the Si / SiGe etch selectivity ratio is >20, preferably >50, and more preferably >340.

[0024] Furthermore, the etching rate of SiGe is <10 Å / min, preferably <5 Å / min, and more preferably <2 Å / min.

[0025] Furthermore, the thermal oxide etching rate is <2 Å / min, preferably <0.2 Å / min.

[0026] Furthermore, the rate of silicon removal can be adjusted by increasing or decreasing etching conditions, such as temperature.

[0027] Furthermore, SiGe inhibitors can be used in combination to further improve the Si / SiGe selectivity ratio.

[0028] Furthermore, the water-miscible organic solvent is preferably miscible with water at a ratio of at least 1:1 (wt) at 20°C and ambient pressure.

[0029] Furthermore, the etching solution may also contain one or more surfactants, including but not limited to:

[0030] Anionic surfactants, amphoteric surfactants, and nonionic surfactants.

[0031] The anionic surfactant is preferably ammonium lauryl sulfate, dodecylbenzene sulfonate, fatty alcohol polyoxyethylene ether sulfate, fatty alcohol polyoxyethylene ether carboxylate, alkyl ether phosphate, or a fluorinated surfactant; the fluorinated surfactant is preferably perfluorodecyltrimethoxysilane, tridecafluorooctylethyltrimethoxysilane, perfluoroalkylsulfonamide salt, perfluorooctane sulfonate, perfluorobutane sulfonate, perfluorononanoate, or perfluorooctanoate.

[0032] Amphoteric surfactants, preferably dodecyl dimethyl betaine, cocamidopropyl hydroxysulfonate betaine, cocamidopropyl-2-hydroxy-3-sulfopropyl betaine, lauramidopropyl betaine, lauramidopropyl hydroxysulfonate betaine, palmitamidopropyl betaine, stearamidopropyl betaine, stearamidopropyl hydroxysulfonate betaine, phosphatidylserine, phosphatidylethanolamine, and phosphatidylcholine.

[0033] Nonionic surfactants are preferably fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, fatty acid methyl ester ethoxylates, fatty acid glycerides, polyoxyethylene fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, and polyether surfactants.

[0034] Furthermore, the surfactant is more preferably a perfluorinated N-substituted alkyl sulfonamide ammonium salt or contains a perfluorinated N-substituted alkyl sulfonamide ammonium salt.

[0035] Furthermore, the preferred surfactant does not contain metals or metal ions.

[0036] Further, the total amount of surfactant is 0.0001-10 wt%, preferably 0.0005-5 wt%, more preferably 0.001-1 wt%, and most preferably 0.002-0.2 wt%.

[0037] Furthermore, the etching solution is preferably an aqueous solution that does not contain surfactants.

[0038] Furthermore, the etching solution may also contain one or more chelating agents, including but not limited to ethylenediaminetetraacetic acid, butanediaminetetraacetic acid, propylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, diethylenetriaminepentaacetic acid, cystine, and gallic acid.

[0039] Further, the total amount of the chelating agent is 0.0001-10 wt%, preferably 0.0005-5 wt%, more preferably 0.001-1 wt%, and most preferably 0.002-0.2 wt%.

[0040] Furthermore, the etching solution is preferably an aqueous solution without chelating agents.

[0041] Furthermore, after etching is complete, the etchant can be easily removed from the microelectronic device by rinsing, washing, or other removal steps. For example, it can be rinsed with a rinsing solution such as deionized water or an organic solvent, and / or dried (e.g., spin-drying, N2, steam drying, etc.); or the entire device structure can be cleaned with an aqueous solution containing 0.5 wt% HF at room temperature for approximately 30-240 seconds, preferably 60 seconds, more preferably 30 seconds to remove the etchant.

[0042] The beneficial effects of this application are as follows:

[0043] The high-performance, high-selectivity etching composition provided in this application can effectively maintain the etching of silicon while providing anti-corrosion effect on silicon and germanium, with a silicon / silicon-germanium selectivity ratio > 20; when furan ring compounds and polyamine compounds are used in combination in a certain proportion, the silicon / silicon-germanium selectivity ratio is as high as 345. Detailed Implementation

[0044] The embodiments of the present invention will be described in detail below with reference to the examples. The following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0045] The etching compositions of the present invention are suitable for microelectronic devices including silicon and silicon germanium, preferably SiGe25, and in particular, layers comprising SiGe alloys or layers thereof (such as high-K materials, low-K materials).

[0046] It should be understood that the term "silicon" as a material deposition on microelectronic devices includes, but is not limited to, amorphous silicon, crystalline silicon, polycrystalline silicon, p-type doped silicon, n-type doped silicon, etc.

[0047] As used herein, "silicon-germanium layer" or "SiGe layer" refers to a layer containing or composed of a silicon-germanium alloy known in the art and represented by the formula SixGey, where x+y=1.00. SiGe25 here refers to y being 0.25.

[0048] As defined in this article, "high-K materials" (materials with high dielectric constants) are typically used to replace traditional silicon dioxide (SiO2) as the dielectric layer of capacitors. High-K materials can be hafnium dioxide (HfO2), hafnium oxynitride (HfON), zirconium dioxide (ZrO2), zirconium oxynitride (ZrON), aluminum oxide (Al2O3), aluminum oxynitride (AlON), hafnium silicon oxide (HfSiO2), hafnium aluminum oxide (HfAlO), zirconium silicon oxide (ZrSiO2), tantalum dioxide (Ta2O5), aluminum oxide, titanium oxide (TiO2), aluminum-doped hafnium dioxide, bismuth strontium titanium (BST), or platinum zirconium titanium (PZT).

[0049] As defined herein, “low-k dielectric material” (material with a dielectric constant < 3.5) refers to any material used as a dielectric material in layered microelectronic devices. Examples include silicon-containing organic polymers, silicon-containing hybrid organic / inorganic materials, organosilicon glasses (OSG), TEOS, fluorinated silicate glasses (FSG), silicon dioxide, and carbon-doped oxide (CDO) glasses. It should be understood that low-k dielectric materials can have different densities and different porosities.

[0050] The abbreviations used in the embodiments and comparative examples of this application are as follows:

[0051] TMAH (tetramethylammonium hydroxide), DIW, TEA (triethanolamine), IPA (isopropanol), PVP (polyvinylpyrrolidone), BTA (benzotriazole), HMTA (hexamethylenetetramine), HDM (1,6-hexanediamine).

[0052] Preparation and etching methods:

[0053] (1) Preparation: According to the components and contents in the table below, weigh the corresponding raw materials by percentage calculation to prepare different selective etching solutions, with water as the balance.

[0054] (2) Etching conditions: 50℃, 300r / min stirring and soaking for 1-10min.

[0055] (3) Etched test piece: Si / SiGe stack, wherein Si (110) and SiGe25.

[0056] The formulations and test data of each embodiment and comparative example are shown in Tables 1-5.

[0057] Table 1. Etching solution formulation ratios and test data for different quinoline compounds.

[0058]

[0059] Table 2. Etching solution formulation ratios and test data for different polyamine compounds.

[0060]

[0061] Table 3. Etching solution formulation ratios and test data for different furan ring compounds.

[0062]

[0063] Table 4. Etching solution formulation ratios and test data for different aromatic ether compounds

[0064]

[0065] Table 5. Preferred embodiment formulation and test data

[0066]

[0067] The experimental data above show that adding compounds such as quinolines, polyamines, furan ring compounds, and aromatic ethers can promote silicon etching and inhibit silicon-germanium etching. Examples 4, 9, and 15 demonstrate that the combined use of the polyamine compound 1,6-hexanediamine and the furan ring compound 2-ethylfuran achieves an etching selectivity as high as 345.

[0068] The foregoing description is primarily for illustrative purposes. Although the invention has been shown and described with respect to exemplary embodiments thereof, those skilled in the art will understand that various other changes, omissions, and additions in form and detail may be made without departing from the spirit and scope of the invention.

Claims

1. A high-performance selective etching solution for silicon in a silicon-germanium / silicon stack, characterized in that, It contains quaternary ammonium hydroxide, alkanolamine, SiGe inhibitor, and water; The SiGe inhibitor is a combination of the polyamine compound 1,6-hexanediamine and the furan ring compound 2-ethylfuran; The quaternary ammonium hydroxide is R4NOH, where R represents four identical or different aliphatic or aromatic groups; the amount of the quaternary ammonium hydroxide used is 0.3-50 wt%. The etching solution includes a water-soluble organic solvent, which is one or more of propanol, isopropanol, propylene glycol, butanol, butyl diethylene glycol, cyclohexane, dimethylformamide, sulfolane, and dimethyl sulfoxide; the amount of the water-soluble organic solvent used is 0.1-60 wt%. The alkanolamine is selected from one or more of monoethanolamine, diethanolamine, 2-(ethylamino)ethanol, 2-dibutylaminoethanol, N,N-diethylethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, and cyclohexylamine diethanolamine; the amount of the alkanolamine used is 0.01-50 wt%. The SiGe inhibitor was used in an amount of 0.001-10 wt%.

2. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of quaternary ammonium hydroxide used is 1-40 wt%.

3. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of quaternary ammonium hydroxide used is 5-30 wt%.

4. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of quaternary ammonium hydroxide used is 10-20 wt%.

5. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of the water-soluble organic solvent used is 1-40 wt%.

6. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of the water-soluble organic solvent used is 2-30 wt%.

7. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of the water-soluble organic solvent used is 5-20 wt%.

8. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of the alkanolamine used is 0.1-40 wt%.

9. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of the alkanolamine used is 0.5-30 wt%.

10. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The amount of the alkanolamine used is 1-20 wt%.

11. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The SiGe inhibitor was used in an amount of 0.002-5 wt%.

12. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The SiGe inhibitor was used in an amount of 0.005-2 wt%.

13. The high-performance selective etching solution for silicon in a silicon-germanium / silicon stack according to claim 1, characterized in that, The SiGe inhibitor was used in an amount of 0.01-0.5 wt%.

14. The use of the etching solution according to any one of claims 1-13 for high-performance selective etching of silicon in silicon-germanium / silicon stacks, characterized in that, The steps are as follows: The etching solution is brought into contact with the microelectronic device containing the silicon-germanium / silicon stack at a temperature of 10℃-100℃ to complete the silicon layer etching; the Si / SiGe etching selectivity ratio is >340; the thermal oxide etching rate is <2 Å / min.

15. The use of the etching solution according to claim 14, characterized in that, Thermal oxide etching <0.2 Å / min.

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