Preparation of germanium-silicon etching liquid
The prepared germanium-silicon etching solution solved the problem of uneven germanium-silicon etching in GAA MOSFETs, achieving highly selective and uniform etching, and improving the electrical performance and stability of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-04-10
AI Technical Summary
In the fabrication of gate-all-around transistors (GAA MOSFETs), uneven etching of germanium and silicon leads to inconsistencies in the nanowire structure, affecting the electrical characteristics and long-term stability of the device.
A germanium-silicon etching solution composed of fluoride, oxidant, wetting agent and complexing agent in a specific ratio is used to etch the sacrificial layer in the GAA MOSFET structure after mixing and stirring, so as to achieve high selectivity and uniformity of germanium-silicon/silicon etching.
Highly selective etching of germanium-silicon/silicon stacks was achieved, improving the uniformity of nanowire structures and the stability of device electrical performance, while reducing threshold voltage fluctuations and leakage current.
Smart Images
Figure SMS_1 
Figure SMS_4
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a kind of germanium silicon etching liquid preparation. BACKGROUND
[0002] In the design of GAA MOSFET, Si and SiGe layers are usually grown alternately to construct a multilayer structure, which is called superlattice. These SiGe layers not only adjust the carrier concentration, but also improve the electron mobility by introducing stress. For example, by epitaxial growth technology, Si and low concentration germanium SiGe layers are alternately grown on a silicon substrate to form a multilayer structure.
[0003] In a gate-all-around transistor (GAA MOSFET), the arrangement and uniformity of germanium silicon (SiGe) / silicon (Si) stack etching is a key technology to achieve high-performance devices. In the manufacturing process of GAA MOSFET, the sacrificial layer needs to be accurately removed to form a nanowire structure. If the etching is not uniform, it may cause the size of the nanowire to be inconsistent, which in turn affects the electrical characteristics of the device, such as threshold voltage fluctuation and increased leakage current. In addition, uneven etching can also cause uneven local stress distribution, affecting the long-term stability of the device. SUMMARY
[0004] The purpose of the present application is to overcome the defects of uneven etching in the manufacturing process of gate-all-around transistor, which affects the electrical characteristics and long-term stability of the device, and to provide a preparation of germanium silicon etching liquid. The germanium silicon etching liquid of the present application can achieve high-selective etching of germanium silicon / silicon when etching the sacrificial layer in GAA MOSFET structure, and the etching effect is good and uniform.
[0005] The present application solves the above technical problems by the following technical solutions.
[0006] The present application provides a kind of germanium silicon etching liquid, which is composed of the following mass fraction of components: 0.1%-5% of fluoride, 5%-70% of oxidizing agent, 0.1%-2% of wetting agent, 0.1%-2% of complexing agent and solvent; The sum of the mass fraction of each component is 100%, and the mass fraction of each component is the percentage of the total mass of the germanium silicon etching liquid.
[0007] In some embodiments of the present application, the fluoride in the germanium silicon etching liquid is one or more of the fluorides commonly used in the art, such as hydrofluoric acid, ammonium fluoride, tetramethylammonium fluoride, ammonium hydrogen fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, fluorosulfonic acid, fluoroboric acid, ammonium hydrogen fluoride, hexafluorosilicic acid, hexafluorosilicate, triethylamine trihydrofluoric acid and pyridine hydrogen fluoride salt, more preferably hydrofluoric acid. When the fluoride is hydrofluoric acid, the mass fraction of hydrogen fluoride in the hydrofluoric acid can be conventional in the art, preferably 45%-55%, for example 49%.
[0008] In some embodiments of the present invention, the mass fraction of the fluoride in the germanium-silicon etching solution is 0.5%-2.5%; for example, 0.1%, 1%, 2.5% or 5%.
[0009] In some embodiments of the present invention, the oxidant in the germanium-silicon etching solution is an oxidant conventionally used in the art, preferably one or more of hydrogen peroxide, peracetic acid, perboric acid, ammonium persulfate, nitric acid, and periodic acid, more preferably hydrogen peroxide. When the oxidant is hydrogen peroxide, the mass fraction of hydrogen peroxide in the hydrogen peroxide can be conventional in the art, preferably 25%-35%, for example 30%.
[0010] In some embodiments of the present invention, the oxidant in the germanium-silicon etching solution has a mass fraction of 20%-60%; for example, 5%, 20%, 50% or 70%.
[0011] In some embodiments of the present invention, the wetting agent in the germanium-silicon etching solution is a cationic surfactant or anionic surfactant, preferably one or more of quaternary ammonium salts, alkyl ammonium salts, carboxylates, sulfonates, and sulfate esters; for example, octadecyl diester quaternary ammonium salt or fatty alcohol polyoxyethylene ether ammonium sulfate.
[0012] In some embodiments of the present invention, the wetting agent in the germanium-silicon etching solution has a mass fraction of 0.5%-1.5%; for example, 1%.
[0013] In some embodiments of the present invention, the complexing agent in the germanium-silicon etching solution is a chelating agent conventionally used in the art that can form a stable complex with metal ions, preferably one or more of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), triethylaminehexaacetic acid (TTHA), ethylenediamine (EDA), hydroxyethylethylenediaminetriacetic acid (HEDTA), and hydroxyethylidene diphosphonic acid (HEDP), more preferably hydroxyethylethylenediaminetriacetic acid (HEDTA) or hydroxyethylidene diphosphonic acid (HEDP).
[0014] In some embodiments of the present invention, the complexing agent in the germanium-silicon etching solution has a mass fraction of 0.5%-1.5%; for example, 1%.
[0015] In some embodiments of the present invention, the solvent in the germanium-silicon etching solution is deionized water or alcohol, preferably deionized water.
[0016] In some embodiments of the present invention, the germanium-silicon etching solution comprises the following components in the indicated mass fractions: 1% of the fluoride, 50% of the oxidant, 1% of the wetting agent, 1% of the complexing agent, and 47% of the solvent; preferably, the germanium-silicon etching solution comprises the following components in the indicated mass fractions: 1% hydrofluoric acid, 50% hydrogen peroxide, 1% octadecyl diester quaternary ammonium salt or fatty alcohol polyoxyethylene ether ammonium sulfate, 1% hydroxyethyl ethylenediamine triacetic acid or hydroxyethylidene diphosphonic acid, and 47% deionized water.
[0017] In some embodiments of the present invention, the germanium-silicon etching solution is composed of any one of the following groups of components by mass fraction:
[0018] (1) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% octadecyl diester quaternary ammonium salt, 1% hydroxyethyl ethylenediamine triacetic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.
[0019] (2) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% octadecyl diester quaternary ammonium salt, 1% hydroxyethylidene diphosphonic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.
[0020] (3) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% fatty alcohol polyoxyethylene ether ammonium sulfate, 1% hydroxyethyl ethylenediamine triacetic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.
[0021] (4) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% fatty alcohol polyoxyethylene ether ammonium sulfate, 1% hydroxyethylidene diphosphonic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.
[0022] The present invention also provides a method for preparing the above-mentioned germanium-silicon etching solution, which includes the following steps: mixing the fluoride, oxidant, wetting agent, complexing agent and solvent as described above to obtain the germanium-silicon etching solution.
[0023] In some embodiments of the invention, the mixing is carried out at room temperature.
[0024] In some embodiments of the present invention, the preparation method specifically includes the following steps: mixing the wetting agent, the complexing agent and the solvent, adding the fluoride, and then mixing with the oxidant;
[0025] Preferably, the wetting agent, the complexing agent, and the solvent are mixed, the fluoride is slowly added, and then mixed with the oxidant and stirred; the stirring is preferably mechanical stirring.
[0026] The present invention also provides an application of the above-mentioned germanium-silicon etching solution in etching the sacrificial layer in a GAA MOSFET structure.
[0027] In some embodiments of the present invention, the germanium-silicon etching solution selectively etches the sacrificial layer in the GAA MOSFET structure.
[0028] In some embodiments of the present invention, the germanium-silicon etching solution makes the etching of the silicon-germanium / silicon stack more uniform.
[0029] In this invention, the term "room temperature" refers to 10-50°C, preferably 15-30°C.
[0030] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.
[0031] The reagents and raw materials used in this invention are all commercially available.
[0032] The positive and progressive effects of this invention are as follows: the germanium-silicon etching solution of this invention can be used in GAA MOSFETs to selectively etch and remove the sacrificial layer forming the nanowires in the channel region, and can highly selectively remove silicon-germanium alloys; at the same time, by adjusting the additives, namely wetting agents and complexing agents, the uniformity of deep hole etching can be significantly improved. Detailed Implementation
[0033] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.
[0034] Preparation Examples 1-4 and Comparative Examples 1-3
[0035] Preparation of germanium-silicon etching solution
[0036] Raw materials for preparation: hydrofluoric acid (hydrogen fluoride mass fraction of hydrofluoric acid is 49%), hydrogen peroxide (hydrogen peroxide mass fraction of hydrogen peroxide is 30%), wetting agent (octadecyl diester quaternary ammonium salt or fatty alcohol polyoxyethylene ether ammonium sulfate), complexing agent (HEDTA (hydroxyethyl ethylenediamine triacetic acid) or HEDP (hydroxyethylidene diphosphonic acid)), deionized water.
[0037] At room temperature, add the wetting agent, complexing agent and deionized water to the container according to the amount of materials in Table 1, and then slowly add hydrofluoric acid. Before use, mix the solution with hydrogen peroxide and stir mechanically until uniform to obtain the germanium-silicon etching solution.
[0038] Table 1. Feed amounts of each raw material component in germanium-silicon etching solution
[0039]
[0040] Application Examples
[0041] 1. Etching Applications
[0042] Etching target: Silicon-germanium alloy (25%Ge) epitaxial wafer 4 A 4cm silicon wafer with a cross-layered structure, formed by cross-layering of germanium-silicon layers and silicon layers. The number of layers in the stacked structure are 32 and 64, respectively.
[0043] Etching conditions: 30℃, 200r / min stirring and soaking.
[0044] Etching time: 10 minutes
[0045] Etching container: Quartz tank.
[0046] 2. Etching tests of stacked structures with different numbers of layers
[0047] Detection method: After etching the wafer for 10 minutes, the wafer was removed, cleaned, dried, and the etching of the stacked structure in the wafer was observed using TEM.
[0048] Evaluation criteria: Grade A is SiGe stack uniformity U% < 5% after germanium-silicon layer etching; Grade B is SiGe stack uniformity U% < 10% after germanium-silicon layer etching; Grade C is SiGe stack uniformity U% > 10% after germanium-silicon layer etching.
[0049] Calculation method: U% = (SiGe etching maximum value - minimum value) / (maximum value + minimum value) 100%
[0050] Measurement method: Thickness was measured using an ellipsometer (JAWoollam Theta-SE spectroscopic ellipsometer), both before and after etching.
[0051] The test results of the etching solutions prepared in Examples 1-4 and Comparative Examples 1-3 are shown below.
[0052]
[0053] The results show that Examples 1-4 can achieve high-selectivity etching of germanium-silicon / silicon, and the etching effect is good and uniform. Comparative Examples 1-3, which do not contain wetting agents and complexing agents, are less selective and have poor etching effect, and the etching rate is significantly limited.
Claims
1. A method for preparing a germanium-silicon etching solution, characterized in that, It includes the following steps: The germanium-silicon etching solution is obtained by mixing fluoride, oxidant, wetting agent, complexing agent and solvent; wherein the mass fraction of fluoride is 0.1%-5%, the mass fraction of oxidant is 5%-70%, the mass fraction of wetting agent is 0.1%-2%, and the mass fraction of complexing agent is 0.1%-2%; the mass fraction is the percentage of the mass of each component to the total mass of the components; the sum of the mass fractions of the components is 100%.
2. The preparation method according to claim 1, characterized in that, The mixing is carried out at room temperature.
3. The preparation method according to claim 1, characterized in that, The preparation method specifically includes the following steps: mixing the wetting agent, the complexing agent, and the solvent, adding the fluoride, and then adding the oxidizing agent.
4. The preparation method according to claim 3, characterized in that, The preparation method specifically includes the following steps: mixing the wetting agent, the complexing agent and the solvent, slowly adding the fluoride, and then mixing it with the oxidant and stirring.
5. The preparation method according to claim 4, characterized in that, The stirring described is mechanical stirring.
6. The preparation method according to claim 1, characterized in that, The germanium-silicon etching solution meets one or more of the following conditions: (1) The fluoride is one or more of hydrofluoric acid, ammonium fluoride, tetramethylammonium fluoride, ammonium hydrogen fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, fluorosulfonic acid, fluoroboric acid, ammonium hydrogen fluoride, hexafluorosilicic acid, hexafluorosilicate, triethylamine trihydrofluoric acid and pyridine hydrofluoric acid. (2) The oxidizing agent is one or more of hydrogen peroxide, peracetic acid, perboric acid, ammonium persulfate, nitric acid and periodic acid; (3) The wetting agent is a cationic surfactant or anionic surfactant; (4) The complexing agent is one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylaminehexaacetic acid, ethylenediamine, hydroxyethylethylenediaminetriacetic acid, and hydroxyethylidene diphosphonic acid; (5) The solvent is deionized water or alcohol; (6) The mass fraction of the fluoride is 0.5%-2.5%; (7) The mass fraction of the oxidant is 20%-60%; (8) The mass fraction of the wetting agent is 0.5%-1.5%; (9) The mass fraction of the complexing agent is 0.5%-1.5%.
7. The preparation method according to claim 6, characterized in that, The germanium-silicon etching solution meets one or more of the following conditions: (1) The fluoride is hydrofluoric acid; (2) The oxidant is hydrogen peroxide; (3) The wetting agent is one or more of the following: quaternary ammonium salt, alkyl ammonium salt, carboxylate, sulfonate and sulfate ester salt; (4) The complexing agent is hydroxyethyl ethylenediamine triacetic acid or hydroxyethylidene diphosphonic acid; (5) The solvent is deionized water; (6) The mass fraction of the fluoride is 1%; (7) The mass fraction of the oxidant is 50%; (8) The mass fraction of the wetting agent is 1%; (9) The mass fraction of the complexing agent is 1%.
8. The preparation method according to claim 7, characterized in that, The germanium-silicon etching solution meets one or more of the following conditions: (1) When the fluoride is hydrofluoric acid, the mass fraction of hydrogen fluoride in the hydrofluoric acid is 45%-55%; (2) When the oxidant is hydrogen peroxide, the mass fraction of hydrogen peroxide in the hydrogen peroxide is 25%-35%; (3) The wetting agent is octadecyl diester quaternary ammonium salt or fatty alcohol polyoxyethylene ether ammonium sulfate.
9. The preparation method according to claim 8, characterized in that, The germanium-silicon etching solution meets one or more of the following conditions: (1) When the fluoride is hydrofluoric acid, the mass fraction of hydrogen fluoride in the hydrofluoric acid is 49%; (2) When the oxidant is hydrogen peroxide, the mass fraction of hydrogen peroxide in the hydrogen peroxide is 30%.
10. The preparation method according to claim 1, characterized in that, The raw materials for the preparation method consist of components in any of the following schemes by mass percentage: (1) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% octadecyl diester quaternary ammonium salt, 1% hydroxyethyl ethylenediamine triacetic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass. (2) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% octadecyl diester quaternary ammonium salt, 1% hydroxyethylidene diphosphonic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass. (3) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% fatty alcohol polyoxyethylene ether ammonium sulfate, 1% hydroxyethyl ethylenediamine triacetic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass. (4) 1% hydrofluoric acid, 50% hydrogen peroxide, 1% fatty alcohol polyoxyethylene ether ammonium sulfate, 1% hydroxyethylidene diphosphonic acid and 47% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.