Controllable Si / SiGe etching solution with low selection ratio and low roughness
By optimizing the etchant composition and process, a precise selectivity ratio of SiGe to Si and low-roughness etching were achieved, overcoming the shortcomings of traditional etchants in terms of selectivity ratio and surface roughness control, and improving the performance and reliability of semiconductor devices.
Patent Information
- Application Number
- CN202511459174.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-13
- Publication Date
- 2026-02-27
AI Technical Summary
Existing wet etching solutions have difficulty in precisely controlling the selectivity ratio when etching SiGe and Si, which can lead to device structure damage or performance degradation. At the same time, the surface roughness is difficult to meet the requirements of advanced processes, affecting device performance and reliability.
By employing a composition of quaternary ammonium hydroxide, fluorinated surfactants, inhibitors, surface smoothers, and polarity enhancers, and by precisely controlling the etching selectivity and surface smoothing, combined with nitrogen treatment, the etching process is optimized to achieve etching effects with low selectivity and low roughness.
It significantly improves etching selectivity and surface smoothness, reduces SiGe surface roughness to below 0.2nm, and enhances the processing yield and performance stability of semiconductor devices.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the field of electronic chemicals, and particularly relates to a low-selectivity low-roughness Si / SiGe etching solution. BACKGROUND
[0002] With the semiconductor nodes entering below 3nm, dry etching (such as plasma etching) has become the core process of advanced devices such as GAA transistors and 3D NAND. However, while dry etching achieves high aspect ratio structures, it inevitably introduces surface / subsurface damage layers. For example, plasma bombardment during etching can cause lattice damage to the material surface, forming irregular rough surfaces; by-products generated by the reaction of etching gas with the material may be left on the sidewall or surface, forming residues that are difficult to remove; in addition, the non-uniformity of etching rate can also cause inconsistent sidewall inclination. These defects, like hidden "reefs" inside the device, can seriously interfere with the electrical performance of the device, increase the leakage current, reduce the carrier mobility, and thus affect the reliability and yield of the device, becoming a key bottleneck restricting the further development of advanced processes.
[0003] In order to overcome the problem of defects after dry etching, chemical wet etching solution modification technology has emerged and quickly become an indispensable key link in advanced processes. Wet etching solution can precisely remove the defect layer generated during dry etching process through specific chemical reactions, and perform smoothing treatment on the material surface, thereby significantly improving the surface quality. However, under the severe requirements of advanced processes, traditional wet etching solution faces many challenges. On the one hand, advanced processes have extremely precise requirements for the etching selectivity between different material layers. In complex semiconductor device structures containing silicon germanium / silicon layers, Si and SiGe layers often interleave with each other, and the wet etching solution needs to have a precisely controllable selectivity to ensure that the defects are removed without causing excessive etching or damage to other key material layers. If the selectivity control is not proper, it may cause device structure damage, performance degradation, and even the entire device failure. On the other hand, advanced processes have reached an unprecedented level of requirements for surface roughness (Ra). With the continuous reduction of device size, the influence of surface roughness on device performance becomes more and more significant. Small surface undulations can cause uneven electric field distribution, increase leakage current and power consumption, and reduce device speed and reliability.
[0004] Therefore, the wet etching solution not only needs to effectively remove defects, but also must be able to reduce the surface roughness to a very low level to meet the needs of advanced processes for high-quality surfaces. At present, although the traditional wet etching technology can remove surface damage through chemical dissolution, it has defects such as difficult to accurately control the selectivity ratio, insufficient difference between the etching rates of SiGe and Si, and poor process repeatability caused by concentration fluctuation. For example, the etching rate of some etching solutions in the prior art is similar to that of Si, which is difficult to achieve selective smoothing processing; while high selectivity etching solution can protect the SiGe layer, but it is easy to cause excessive etching of the Si layer, causing new surface defects.
[0005] Therefore, there is a need in the art for an etching composition aimed at providing an accurately controllable low selectivity ratio through chemical dissolution; while achieving material surface smoothing to meet the needs of advanced processes for high-quality surfaces. SUMMARY
[0006] To solve the above technical contradictions, the present patent proposes a low selectivity and low roughness Si / SiGe etching solution.
[0007] The etching composition of the present application realizes controllable smoothing processing of the defect layer of dry etching through formula innovation and process integration, significantly improves the processing yield and performance stability of semiconductor devices, and provides key technical support for advanced process nodes. The etching solution comprises: (A) a quaternary ammonium hydroxide selected from those satisfying the following formula: R4NOH, wherein R is four identical or different aliphatic 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, and 2-hydroxyethyltrimethylammonium hydroxide.
[0008] Further, the amount of the quaternary ammonium hydroxide is 0.1-20 wt%, preferably 0.5-10 wt%, and most preferably 1-5 wt%.
[0009] (B) a fluorine surfactant selected from one or more of fluorodecyltrimethoxysilane (FC-8), tridecafluorooctyl ethyl trimethoxysilane (F13TEOS), tetraethylammonium perfluorooctane sulfonate (FC248), etc. Further, the amount of the fluorine surfactant is 0.00001-20 wt%, preferably 0.0001-10 wt%, more preferably 0.001-5 wt%, and most preferably 0.002-1 wt%.
[0010] (C) Inhibitors selected from one or more of long chain mercapto compounds, mercapto polyethylene glycol derivatives, mercapto silane coupling agents, including but not limited to long chain mercapto compounds, mercapto polyethylene glycol derivatives, mercapto silane coupling agents.
[0011] Further, the long chain mercapto compounds are selected from one or more of mercaptoethanol, mercapto propanol, ethyl mercapto alcohol, propyl mercapto alcohol, mercapto acetic acid, 11-mercapto undecanoic acid, mercapto benzimidazole, 2- mercaptoethylamine, and the like or mixtures thereof.
[0012] Further, the mercapto polyethylene glycol derivatives are selected from one or more of compounds having the following formula and mixtures thereof: R1-(CH2CH2O) n -R2 wherein: R1, R2: at least one end is mercapto (-SH), the other end can be mercapto, methoxy, carboxyl or other functional groups.
[0013] n: degree of polymerization, determines the molecular weight (common range 100-20000); Preferably, the single end mercapto polyethylene glycol, double end mercapto polyethylene glycol, including but not limited to HS-PEG-NH2, HS-PEG-COOH, HS-PEG-OH, HS-PEG-SH. Further, the mercapto silane coupling agent is selected from one or more of γ-mercaptopropyl trimethoxysilane (KH590), 3-(octanoylthio)propyl triethoxysilane (NXT), bis-(3-triethoxysilylpropyl) tetrasulfide (Si-69), mercaptobenzotriazole silane or mixtures thereof.
[0014] Further, the amount of said inhibitors is 0.00001-20 wt%, preferably 0.0001-10 wt%, more preferably 0.001-5 wt%, most preferably 0.002-1 wt%.
[0015] (D) Surface smoothing agents - polyvinylpyrrolidone (PVP) Further, the viscosity K value of said PVP is 8-100, preferably 10-40, most preferably 12-20; Further, preferably, the amount of PVP is 0.0001-1 wt%, most preferably 0.001-0.01 wt%.
[0016] - polyethylene glycol octylphenyl ether (Triton X-100) Further, preferably, the amount of Triton X-100 is 0.0001-1 wt%, most preferably 0.001-0.01 wt%.
[0017] (E) a polarity enhancer selected from one or more of short chain alcohols (such as propanol), N,N,N-trimethylglycine (betaine), dimethylsulfoxide (DMSO), higher alcohols (such as lauryl alcohol), tetramethylammonium chloride (TMAC), maleic anhydride, or mixtures thereof.
[0018] Further, the polarity enhancer is used in an amount of 0.5-20 wt%, most preferably 1-15 wt%.
[0019] (F) water, in each case the remainder to 100 wt% of the total composition.
[0020] All based on the total weight of the composition, wherein the etching composition pH is preferably in the range of 7 to 12 and wherein the wt% of each component adds up to 100 wt% in each case.
[0021] The present application also provides an etching method using the above composition, which provides a precisely controllable selectivity ratio by chemical dissolution, while achieving material surface smoothing to meet the demand of advanced processes for high quality surfaces. The steps are as follows: The etching liquid needs to be pre-treated with nitrogen (N2) before use. The nitrogen filling time is preferably controlled in the range of 0.5 hours to 6 hours, most preferably 1 hour to 3 hours.
[0022] The etching liquid needs to be continuously and stably supplied with nitrogen (N2) during use to ensure the stability of the etching liquid performance and the consistency of the etching effect.
[0023] The etching liquid is contacted with a microelectronic device containing a silicon / silicon germanium stack at a temperature of 20-70°C to complete the Si / SiGe layer etching.
[0024] Further, the contact time is <24h, preferably 1-60min.
[0025] Further, the contact temperature is 10-100°C, preferably 20-70°C, more preferably 25-60°C.
[0026] Further, the Si / SiGe etching selectivity ratio is preferably 0.5~2, most preferably 1~1.5.
[0027] Further, the etching rate of SiO2 is preferably <0.1 Å / min, more preferably <0.01 Å / min.
[0028] Further, the rate of Si / SiGe removal can be adjusted by increasing or decreasing the etching conditions, such as component content, temperature.
[0029] Further, prior to etching, the entire device structure is cleaned with an aqueous solution containing 0.5 wt% HF at room temperature for about 30 s to 240 s, preferably 60 s, more preferably 30 s. After the etching is complete, the etching solution can be easily removed from the microelectronic device by rinsing, washing or other removal steps. For example, the etching solution can be removed by rinsing with a rinsing solution such as deionized water or an organic solvent, and / or drying (e.g., spin-drying, N2, vapor drying, etc.).
[0030] The etching composition of the present application is suitable for use with microelectronic devices including silicon and silicon germanium, preferably SiGe25, and in particular layers comprising or consisting of SiGe alloys (e.g., high K materials, low K materials).
[0031] It is understood that the term "silicon" as a material deposited on a microelectronic device includes, but is not limited to, comprising amorphous silicon, crystalline silicon, polysilicon, p-type doped silicon, n-type doped silicon, etc.
[0032] As used herein, "silicon germanium containing layer" or "SiGe layer" corresponds to a layer comprising or consisting of a silicon germanium alloy known in the art and represented by the formula Si x Ge y wherein x + y = 1.00. SiGe 25 Herein, y is 0.25.
[0033] As defined herein, "high K material" (material with high dielectric constant) is generally used to replace traditional silicon dioxide (SiO2) as the dielectric layer of a capacitor. 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 pentoxide (Ta2O5), aluminum oxide, titanium oxide (TiO2), aluminum doped hafnium dioxide, bismuth strontium titanium (BST) or platinum zirconium titanium (PZT).
[0034] As defined herein, "low K dielectric material" (material with dielectric constant < 3.5) corresponds to any material used as a dielectric material in layered microelectronic devices. For example, silicon containing organic polymers, silicon containing hybrid organic / inorganic materials, organosilicate glass (OSG), TEOS, fluorinated silicate glass (FSG), silicon dioxide and carbon doped oxide (CDO) glass. It is understood that low K dielectric materials can have different densities and different porosities.
[0035] The present application has the following advantages: Low selectivity etching solution formula design: By optimizing the synergistic effect of quaternary ammonium hydroxide, fluorine surfactant, inhibitor, surface smoothing agent, polarity enhancer and water, the etching rate ratio of Si to SiGe is controlled in the range of 1.2:1 to 1.5:1. The selectivity can effectively remove the defect layer generated by dry etching, avoid excessive etching of SiGe layer, and significantly reduce the corrosion of SiO2 by adding silicon dioxide corrosion inhibitor, ensuring the integrity of the device insulating layer.
[0036] Low roughness etching process optimization: By optimizing the surface smoothing agent composition and adjusting the etching solution temperature, stirring rate and etching time, and combining with the nitrogen-filled etching technology of etching solution, the etching uniformity is improved while removing surface defects. Experiments show that this process can reduce the SiGe surface roughness to below 0.2 nm, meeting the surface flatness requirements of 14 nm and below node devices. DETAILED DESCRIPTION
[0037] The embodiments of the present application will be described in detail below with reference to the examples, which are only used to illustrate the present application and should not be regarded as limiting the scope of the present application.
[0038] (1) Preparation: According to the components and contents in the following table, the corresponding mass of each raw material is calculated by percentage to prepare different selective etching solutions, and water is the balance.
[0039] (2) Etching conditions: N2 pre-treatment for 2h, 30℃, 300r / min stirring immersion for 1-30min.
[0040] (3) Etching test piece: Si (100), Si (111), SiGe25 The formula and test data of each example and comparative example are shown in Tables 1-5. Table 1 Different nonionic surfactant etching solution formula proportion and test data
[0041] Table 2 Different inhibitor etching solution formula proportion and test data
[0042] Table 3 Different surface smoothing agent etching solution formula proportion and test data
[0043] Table 4 Different polarity enhancer etching solution formula proportion and test data
[0044] As shown in Table 1, the etching rate of Si is significantly reduced by adding fluorine ion surfactant. This is because fluorine atoms are adsorbed on the Si / SiGe surface, which promotes the uniform spreading of the etching solution by reducing the solid-liquid interfacial tension, and reduces local over-etching or residue. At the same time, the Si / SiGe selectivity ratio is reduced to 1.27, indicating that the fluorine ion surfactant can effectively inhibit the etching of Si and improve the selectivity. On the basis of the fluorine ion surfactant formula, a mercapto-containing inhibitor (Table 2) is added, which can realize lower etching rate and more stable selectivity by synergistic effect with the fluorine ion surfactant through chemical adsorption. The Ra of Example 4 in Table 3 (0.138 nm) is lower than that of the comparative examples using Triton X-100 (0.195 nm) or PVP (0.189 nm), which confirms the synergistic smoothing effect of multiple components, and the composite formula has better control of anisotropic etching. Finally, the polar enhancer can increase the directional adsorption of the surfactant by electrostatic shielding and polarity regulation, and has a significant synergistic effect on improving the selectivity and surface quality.
[0045] The foregoing description is mainly for the purpose of illustration. Although the present application has been shown and described with respect to exemplary embodiments thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions in the form and detail thereof can be made therein without departing from the spirit and scope of the application.
Claims
1. A low selectivity, low roughness Si / SiGe etching solution, characterized in that, The etching solution comprises the following components by mass fraction: Quaternary ammonium hydroxide 0.1-20 wt% Fluorinated surfactants 0.00001-10 wt%; Inhibitor 0.00001-20 wt%; Surface smoothing agent 0.0001-1wt%; Polarity enhancer 0.5-20wt%; The remainder is water.
2. The low selectivity, low roughness Si / SiGe etching solution according to claim 1, characterized in that, The quaternary ammonium hydroxide is R4NOH, wherein R is four identical or different aliphatic or aromatic groups, selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, ethyltrimethylammonium hydroxide, benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, and 2-hydroxyethyltrimethylammonium hydroxide; the amount of the quaternary ammonium hydroxide is 0.5-10 wt%, most preferably 1-5 wt%.
3. The low selectivity, low roughness Si / SiGe etching solution according to claim 1, characterized in that, The fluorosurfactant is selected from one or more of fluorodecyltrimethoxysilane, tridecafluorooctylethyltrimethoxysilane, and tetraethylammonium perfluorooctylsulfonate; the amount of the fluorosurfactant is 0.001-2 wt%, most preferably 0.002-1 wt%.
4. The low selectivity, low roughness Si / SiGe etching solution according to claim 1, characterized in that, The inhibitor is selected from one or more of long-chain thiol compounds, thiol polyethylene glycol derivatives, and thiol silane coupling agents, and the amount of the inhibitor is 0.0001-10 wt%, more preferably 0.001-5 wt%, and most preferably 0.002-1 wt%.
5. The low selectivity, low roughness Si / SiGe etching solution according to claim 4, characterized in that, The long-chain thiol compounds are selected from one or more of mercaptoethanol, mercaptopropanol, ethyl mercaptool, propyl mercaptool, mercaptoacetic acid, 11-mercaptoundecanoic acid, mercaptobenzimidazole, and 2-mercaptoethylamine.
6. A low selectivity, low roughness Si / SiGe etching solution according to claim 4, characterized in that, The mercaptopolyethylene glycol derivative is selected from compounds having the following formula and mixtures thereof: R1- (CH2CH2O) n -R2 in: R1, R2: At least one end is a thiol group (-SH), and the other end is any one of a thiol group, methoxy group, or carboxyl group; n: Degree of polymerization, resulting in a molecular weight of 1000-20000.
7. The low selectivity, low roughness Si / SiGe etching solution according to claim 4, characterized in that, The mercaptosilane coupling agent is selected from one or more of γ-mercaptopropyltrimethoxysilane, 3-(octanoylthio)propyltriethoxysilane, bis-(3-triethoxysilylpropyl)tetrasulfide, and mercaptobenzotriazole silane.
8. The low selectivity, low roughness Si / SiGe etching solution according to claim 1, characterized in that, The surface smoothing agent is polyvinylpyrrolidone (PVP) or polyethylene glycol octylphenyl ether; the amount of surface smoothing agent used is 0.001-0.01 wt%. The polarity enhancer is selected from one or more of C1-C4 alcohols, N,N,N-trimethylglycine, dimethyl sulfoxide, higher alcohols, tetramethylammonium chloride, maleic anhydride, or mixtures thereof, and the amount of the polarity enhancer is 1-15 wt%.
9. The use of a low selectivity, low roughness Si / SiGe etching solution according to any one of claims 1-8, characterized in that, The etching solution is used to modify the defect layer generated during the dry etching process of microelectronic devices containing silicon-germanium / silicon stacks, and to smooth the material surface with a low selectivity.
10. The use of the low selectivity, low roughness Si / SiGe etching solution according to claim 9, characterized in that, The method of using the etching solution in a composite semiconductor device comprising silicon and silicon-germanium includes the following steps: A composite semiconductor device comprising a silicon-germanium / silicon stack is contacted with an etchant according to any one of claims 1-8; and the semiconductor device is rinsed after the silicon and silicon-germanium have been at least partially removed, wherein the etch selectivity of silicon relative to silicon-germanium is preferably 0.5 to 2, and most preferably 1 to 1.5; The method further includes the step of drying the microelectronic device; the contact step is carried out at a temperature of 10°C-100°C while continuously charging with N2, and the contact temperature is preferably 20-70°C, more preferably 25-60°C.