Application of germanium-silicon etching liquid with high selection ratio

Abstract

The invention discloses an application of a germanium-silicon etching solution with a high selection ratio. Specifically, the invention provides an application of the germanium-silicon etching liquid in selective etching of a sacrificial layer in a GAA MOSFET (Good Acrylic Acid Metal-Oxide-Semiconductor Field Effect Transistor) structure. The germanium-silicon etching liquid is prepared from the following components in percentage by mass: 0.1%-5% of fluoride, 5%-70% of an oxidizing agent, 0.1%-2% of an inhibitor and 1%-5% of a buffer component and a solvent, the sum of the mass percents of all the components is 100%, and the mass percents are the mass percents of all the components in the total mass of the germanium-silicon etching liquid; and the inhibitor is an EO-PO polymer. The germanium-silicon etching liquid can selectively accelerate the etching rate of a silicon-germanium alloy, and has a relatively high selection ratio.

Description

Technical Field

[0001] This invention relates to the application of a high selectivity germanium-silicon etching solution. Background Technology

[0002] With the continuous shrinking of ultra-high-density integrated circuit (UHDIC) dimensions and significant improvements in performance and functionality, the technology node of integrated circuits has dropped below 10nm. Against this backdrop, the difficulty of precisely controlling the electrical characteristics of semiconductor devices has increased dramatically. Compared to the traditional planar gate MOSFET structure, the FinFET significantly enhances the gate's control over the channel region by surrounding the gate on three sides of the fin-shaped channel. The gate-all-around MOSFET (GAAMOSFET) is similar to FinFET, but because its gate electrode completely surrounds the channel, it has greater potential for channel electrostatic control.

[0003] In gate-all-around (GAA) MOSFETs, the typical fabrication method for the channel region involves epitaxially growing a structure consisting of alternating channel and sacrificial layers (i.e., an epitaxial stack) on a substrate. The sacrificial and channel layers are composed of two different materials: alternating silicon (Si) layers and silicon-germanium alloy (SiGe) layers. Subsequently, the sacrificial layers are removed using a selective etching process, forming the nanowire structure of the channel region. During the fabrication of GAA MOSFETs, depending on the specific process requirements, selective etching solutions for Si / SiGe or SiGe / Si are used to achieve precise removal of the different material layers.

[0004] Therefore, high-rate etching of silicon-germanium (SiGe) / silicon (Si) is crucial in the fabrication of gate-all-around transistors. This process directly affects not only the formation efficiency of nanowire or nanosheet structures but also determines the device's performance and yield. High-rate etching can significantly shorten manufacturing time, improve production efficiency, and thus reduce manufacturing costs, which is particularly important for large-scale integrated circuit production. Furthermore, by precisely controlling the etching rate and selectivity, the dimensional uniformity and consistency of nanowires can be ensured, thereby optimizing the device's electrical performance, such as reducing leakage current, improving mobility, and enhancing stability. In modern semiconductor manufacturing, as device dimensions continue to shrink, the requirements for the precision and efficiency of etching processes are becoming increasingly stringent. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of existing germanium-silicon etching solutions, such as low etching rate of germanium-silicon (SiGe) and low etching selectivity of germanium-silicon (SiGe) / silicon. The present invention provides a germanium-silicon etching solution with high selectivity, which has high etching rate and high etching selectivity of germanium-silicon (SiGe) / silicon.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] This invention provides a germanium-silicon etching solution, which is composed of the following components by mass percentage: 0.1%-5% fluoride, 5%-70% oxidant, 0.1%-2% inhibitor, 1%-5% buffer component and solvent; the sum of the mass percentages of each component is 100%, and the mass percentages are the percentages of the mass of each component to the total mass of the germanium-silicon etching solution; the inhibitor is an EO-PO polymer.

[0008] In one embodiment of the present invention, the fluoride in the germanium-silicon etching solution is a fluoride conventionally used in the art, preferably 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 compounds, 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%.

[0009] In one aspect of the present invention, the fluoride in the germanium-silicon etching solution has a mass percentage of 0.5%-2% (e.g., 1%).

[0010] In one embodiment of the present invention, the oxidant in the germanium-silicon etching solution is hydrogen peroxide. The hydrogen peroxide contains a mass fraction of hydrogen peroxide that is conventional in the art, preferably 25%-35%, for example, 30%.

[0011] In one aspect of the present invention, the oxidant in the germanium-silicon etching solution has a mass percentage of 10%-50%, preferably 20%-50% (e.g., 30%).

[0012] In one aspect of the present invention, the EO-PO polymer in the germanium-silicon etching solution may be a polyoxyethylene-polyoxypropylene block polymer, preferably one or more of EO-PO polymer L42, EO-PO polymer L43 and EO-PO polymer L44, and more preferably EO-PO polymer L42.

[0013] In one aspect of the present invention, the mass percentage of the inhibitor in the germanium-silicon etching solution is 0.5%-1% (e.g., 1%).

[0014] In one embodiment of the present invention, the buffer component in the germanium-silicon etching solution is one or more of phosphoric acid, citric acid, carbonic acid, acetic acid, barbituric acid and tris(hydroxymethyl)aminomethane (Tris), preferably citric acid.

[0015] In one embodiment of the present invention, the buffer component in the germanium-silicon etching solution has a mass percentage of 1%-2% (e.g., 1%) to maintain the pH stability of the system.

[0016] In one aspect of the present invention, the solvent in the germanium-silicon etching solution is deionized water or an alcohol solvent, preferably deionized water.

[0017] In one embodiment of the present invention, the germanium-silicon etching solution is composed of the following components by mass percentage: 1% hydrofluoric acid, 20%-50% hydrogen peroxide, 1% EO-PO polymer, 1% citric acid, and deionized water; the sum of the mass percentages of each component is 100%, and the mass percentage is the percentage of the mass of each component to the total mass of the germanium-silicon etching solution; in the hydrofluoric acid, the mass fraction of hydrogen fluoride is 49%; in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 30%; and the EO-PO polymer is EO-PO polymer L42 or EO-PO polymer L43.

[0018] In certain preferred embodiments of the present invention, the germanium-silicon etching solution is composed of components in any of the following mass percentages:

[0019] (1) 30% hydrogen peroxide, 1% hydrofluoric acid, 1% EO-PO polymer L42, 1% citric acid and 67% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.

[0020] (2) 30% hydrogen peroxide, 1% hydrofluoric acid, 1% EO-PO polymer L43, 1% citric acid and 67% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; and wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.

[0021] (3) 20% hydrogen peroxide, 1% hydrofluoric acid, 1% EO-PO polymer L42, 1% citric acid and 77% deionized water; wherein the hydrofluoric acid contains 49% hydrogen fluoride by mass; and wherein the hydrogen peroxide contains 30% hydrogen peroxide by mass.

[0022] (4) 50% hydrogen peroxide, 1% hydrofluoric acid, 1% EO-PO polymer L42, 1% citric 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.

[0023] 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, inhibitor, buffer component and solvent as described above to obtain the germanium-silicon etching solution.

[0024] In one aspect of the invention, the mixing is carried out at room temperature.

[0025] In one embodiment of the present invention, the preparation method includes the following steps: adding the fluoride and the oxidant sequentially to a mixed solution of the inhibitor, the buffer component and the solvent, and stirring to obtain the germanium-silicon etching solution.

[0026] In one aspect of the present invention, the stirring in the preparation method is a conventional stirring operation in the art, preferably mechanical stirring.

[0027] The present invention also provides an application of the above-mentioned germanium-silicon etching solution in the sacrificial layer of a selectively etched GAA MOSFET structure.

[0028] In one aspect of the present invention, the germanium-silicon etching solution can selectively accelerate the removal rate of silicon-germanium alloy oxides.

[0029] In one aspect of the present invention, the germanium-silicon etching solution can improve the etching selectivity for silicon-germanium alloy / silicon.

[0030] In this invention, the term "room temperature" refers to 10-50°C, preferably 15-30°C.

[0031] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0032] The reagents and raw materials used in this invention are all commercially available. Among them, the EO-PO polymer L42 was purchased from Nantong Jinlai Chemical Co., Ltd.

[0033] 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 to form the nanowires of the channel region, and can selectively accelerate the oxidation rate and oxide removal rate of silicon-germanium alloys, and etch silicon-germanium alloys at a high rate. Detailed Implementation

[0034] 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.

[0035] Preparation Examples 1-4 and Comparative Examples 1-4

[0036] Preparation of germanium-silicon etching solution

[0037] Raw materials: hydrofluoric acid (hydrogen fluoride mass fraction of hydrofluoric acid is 49%), oxidant (hydrogen peroxide mass fraction of hydrogen peroxide in hydrogen peroxide is 30%), inhibitor (see Table 1 for specific types), buffer component (citric acid), deionized water.

[0038] At room temperature, add the inhibitor, buffer component and deionized water to the container according to the amount of materials in Table 1, and then slowly add hydrofluoric acid and oxidant in sequence. Stir mechanically until homogeneous to obtain germanium-silicon etching solution.

[0039] Table 1 Mass of each raw material component of germanium-silicon etching solution

[0040] .

[0041] Application Examples

[0042] 1. Germanium-silicon etching rate

[0043] Etching rate test sample: Silicon-germanium alloy (25%Ge) epitaxial wafer 4 4cm.

[0044] Etching conditions: 30℃, 200r / min stirring and soaking.

[0045] Etching time: 5 minutes

[0046] Etched container: Quartz tank

[0047] Measurement method: Thickness was measured using an ellipsometer (JAWoollam Theta-SE spectrometer). The thickness of the sample was measured before and after etching. The etching rate was calculated by dividing the difference between the initial thickness and the etched thickness by the etching time (minutes). The selectivity ratio represents the ratio of the germanium-silicon etching rate (SiGe E / R) to the silicon etching rate (Si E / R).

[0048] 2. Si etching rate

[0049] Etching rate test sample: silicon wafer 4 4cm.

[0050] Etching conditions: 30℃, 200r / min stirring and soaking.

[0051] Etching time: 1 hour

[0052] Etched container: Quartz tank

[0053] Measurement method: Thickness was measured using an ellipsometer (JAWoollam Theta-SE spectrometer). The thickness of the sample was measured before and after etching. The etching rate was calculated by dividing the difference between the initial thickness and the etched thickness by the etching time (minutes). The selectivity ratio represents the ratio of the germanium-silicon etching rate (SiGe E / R) to the silicon etching rate (Si E / R).

[0054] The etching rates of the germanium-silicon etching solutions of Examples 1-4 and Comparative Examples 1-4 are shown in Table 2.

[0055] Table 2

[0056] .

Claims

1. Use of a germanium silicon etching liquid in the selective etching of a sacrificial layer in a GAA MOSFET structure, characterized in that, The germanium-silicon etching liquid is composed of the following components with mass percentage: 0.1%-5% of fluoride, 5%-70% of oxidant, 0.1%-2% of inhibitor, 1%-5% of buffer component and solvent; the sum of the mass percentage of each component is 100%, the mass percentage is the percentage of the mass of each component in the total mass of the germanium-silicon etching liquid; the inhibitor is EO-PO polymer.

2. Use according to claim 1, wherein The germanium-silicon etching liquid can selectively accelerate the removal rate of silicon-germanium alloy oxide.

3. Use according to claim 2, wherein the compound is ###0002### The mass percentage of the inhibitor is 0.5%-1%.

4. The use according to claim 3, wherein the compound is ###0002### The germanium-silicon etching liquid meets one or both of the following conditions: (1) the EO-PO polymer is one or more of EO-PO polymer L42, EO-PO polymer L43 and EO-PO polymer L44; (2) the mass percentage of the inhibitor is 1%.

5. The use according to claim 4, wherein the compound is ###0002### The EO-PO polymer is EO-PO polymer L42.

6. Use according to any one of claims 1 to 5, wherein The germanium-silicon etching liquid meets one or more of the following conditions: (1) the fluoride is one or more of hydrofluoric acid, ammonium fluoride, tetramethylammonium fluoride, ammonium bifluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, fluorosulfonic acid, fluoroboric acid, ammonium bifluoride, hexafluorosilicic acid, hexafluorosilicate, triethylamine trihydrofluoric acid and pyridine hydrofluoric acid salt compound; (2) the oxidant is hydrogen peroxide; (3) the buffer component is one or more of phosphoric acid, citric acid, carbonic acid, acetic acid, barbituric acid and tris-hydroxymethyl aminomethane; (4) the solvent is deionized water or alcohol solvent; (5) the mass percentage of the fluoride is 0.5%-2%; (6) the mass percentage of the oxidant is 10%-50%; (7) the mass percentage of the buffer component is 1%-2%.

7. Use according to claim 6, wherein The germanium-silicon etching liquid meets one or more of the following conditions: (1) the fluoride is hydrofluoric acid; (2) in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 25%-35%; (3) the buffer component is citric acid; (4) the solvent is ionized water; (5) the mass percentage of the fluoride is 1%; (6) the mass percentage of the oxidant is 20%-50%; (7) the mass percentage of the buffer component is 1%.

8. Use according to claim 7, wherein the compound is ###0002### The germanium-silicon etching liquid meets one or more of the following conditions: (1) when the fluoride is hydrofluoric acid, in the hydrofluoric acid, the mass fraction of hydrogen fluoride is 45%-55%; (2) in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 30%; (3) the mass percentage of the oxidant is 30%.

9. The use according to claim 1, wherein The germanium-silicon etching solution is composed of the following components with mass percentage: 1% of hydrofluoric acid, 20%-50% of hydrogen peroxide, 1% of EO-PO polymer, 1% of citric acid and deionized water; the sum of the mass percentages of the components is 100%, the mass percentage is the percentage of the mass of each component in the total mass of the germanium-silicon etching solution; in the hydrofluoric acid, the mass fraction of hydrogen fluoride is 49%; in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 30%; the EO-PO polymer is EO-PO polymer L42 or EO-PO polymer L43.

10. The use according to claim 1, wherein The germanium-silicon etching solution is composed of the following components with mass percentage: (1) 30% of hydrogen peroxide, 1% of hydrofluoric acid, 1% of EO-PO polymer L42, 1% of citric acid and 67% of deionized water; in the hydrofluoric acid, the mass fraction of hydrogen fluoride is 49%; in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 30%; (2) 30% of hydrogen peroxide, 1% of hydrofluoric acid, 1% of EO-PO polymer L43, 1% of citric acid and 67% of deionized water; in the hydrofluoric acid, the mass fraction of hydrogen fluoride is 49%; in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 30%; (3) 20% of hydrogen peroxide, 1% of hydrofluoric acid, 1% of EO-PO polymer L42, 1% of citric acid and 77% of deionized water; in the hydrofluoric acid, the mass fraction of hydrogen fluoride is 49%; in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 30%; (4) 50% of hydrogen peroxide, 1% of hydrofluoric acid, 1% of EO-PO polymer L42, 1% of citric acid and 47% of deionized water; in the hydrofluoric acid, the mass fraction of hydrogen fluoride is 49%; in the hydrogen peroxide, the mass fraction of hydrogen peroxide is 30%.