Germanium-silicon etching solution
By preparing a silicon germanium etching solution containing organic base, nonionic surfactant and organic solvent, the problem of selective etching of silicon-germanium alloy layer in the GAA MOSFET structure is solved, and efficient silicon etching and low damage process effects are achieved.
Patent Information
- Application Number
- CN202311847687.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-07-01
AI Technical Summary
There is a lack of an etching solution that can selectively etch silicon in a fully surround gate transistor (GAA MOSFET) structure, and in particular, the etching selectivity of the silicon-germanium alloy layer is poor.
A silicon germanium etching solution is provided, which contains 1-10% organic alkali, 0.001-0.1% nonionic surfactant, 5-30% organic solvent and water, and the composition ratio is 100%, so as to achieve a high etching rate of silicon and a low etching rate of silicon-germanium alloy, silicon oxide, and silicon nitride, and a high selectivity of silicon/silicon-germanium alloy.
A high etch rate for silicon is achieved, a low etch rate for silicon-germanium alloy, silicon oxide and silicon nitride, and a high selectivity ratio for silicon/silicon-germanium alloy to meet process requirements.
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Abstract
Description
Technical Field
[0001] The present invention relates to a germanium-silicon etching solution. Background Art
[0002] With the reduction in the size, increase in speed and functionality of ultra-high density integrated circuits, the technology node of integrated circuits has shrunk to below 10 nm, and the precise control of various electrical characteristics of semiconductor devices has become more challenging. Compared with the planar gate MOSFET structure, the fin field-effect transistor (FinFET) enhances the gate's control ability over the channel region by wrapping the gate around three sides of the fin-shaped channel. The gate-all-around FET (GAA MOSFET) is similar to the FinFET, but since the gate electrode completely surrounds the channel, it has a higher potential for electrostatic control over the channel.
[0003] In a GAA MOSFET, a typical manufacturing method for the channel region includes epitaxially growing a stack of a channel layer and a sacrificial layer (epi-stack) on top of a bulk substrate. The sacrificial layer and the channel layer are composed of two different materials (alternating silicon (Si) and silicon-germanium alloy (SiGe) layers), and then the sacrificial layer is removed by selective etching to form nanowires in the channel region. According to process requirements, in a GAA MOSFET structure, a selective etching solution that etches silicon well and etches the silicon-germanium alloy layer poorly is required due to the different deposition materials of the sacrificial layer and the channel layer. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the lack of an etching solution that can selectively etch silicon in a GAA MOSFET structure. To this end, the present invention provides a germanium-silicon etching solution. The germanium-silicon etching solution of the present invention has a relatively high etching rate for silicon, a relatively low etching rate for silicon-germanium alloy, silicon oxide, and silicon nitride, and a high silicon / silicon-germanium alloy selectivity.
[0005] In a first aspect of the present invention, an etching solution is provided. The etching solution contains components with the following mass fractions: 1-10% organic base, 0.001-0.1% non-ionic surfactant, 5-30% organic solvent, and water, and the sum of the mass fractions of each component is 100%.
[0006] In one embodiment, the organic base is one or more of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or ammonium hydroxide, preferably tetramethylammonium hydroxide.
[0007] In one embodiment, the mass fraction of the organic base is 1%, 3%, 5%, 7%, or 10%.
[0008] In one embodiment, the non-ionic surfactant is a non-ionic surfactant commonly used in etching solutions in the art, preferably an EO-PO polymer, more preferably one or more of EO-PO polymer L42, EO-PO polymer L43 or EO-PO polymer L44, and most preferably EO-PO polymer L42.
[0009] In one embodiment, the mass fraction of the non-ionic surfactant is 0.005% - 0.05%, for example 0.01%.
[0010] In one embodiment, the organic solvent is an organic solvent commonly used in etching solutions in the art, preferably an alcohol solvent and / or an alcohol ether solvent, more preferably one or more of ethylene glycol, 1,4-butanediol, glycerol, xylitol, sorbitol polyol, diethylene glycol monoether or diether, dipropylene glycol monoether or diether, for example one or more of diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monopropyl ether, dipropylene glycol monomethyl ether or dipropylene glycol diethyl ether, and most preferably diethylene glycol monoethyl ether.
[0011] In one embodiment, the mass fraction of the organic solvent is 10% - 30%, preferably 10%, 15%, 20%, 25% or 30%.
[0012] In one embodiment, the water is water commonly used in etching solutions in the art, preferably one or more of deionized water, distilled water or ultrapure water.
[0013] In one embodiment, the etching solution comprises the following components in mass fractions: 1% - 10% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% - 30% diethylene glycol monoethyl ether and the balance deionized water.
[0014] In one embodiment, the raw materials of the etching solution include any combination of the following components in mass fractions:
[0015] Combination 1: 1% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether and deionized water, with deionized water making up the balance;
[0016] Combination 2: 3% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether and deionized water, with deionized water making up the balance;
[0017] Combination 3: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether and deionized water, with deionized water making up the balance;
[0018] Composition 4: 7% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether, and deionized water, with the balance made up by deionized water;
[0019] Composition 5: 10% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether, and deionized water, with the balance made up by deionized water;
[0020] Composition 6: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 15% diethylene glycol monoethyl ether, and deionized water, with the balance made up by deionized water;
[0021] Composition 7: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 20% diethylene glycol monoethyl ether, and deionized water, with the balance made up by deionized water;
[0022] Composition 8: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 25% diethylene glycol monoethyl ether, and deionized water, with the balance made up by deionized water;
[0023] Composition 9: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 30% diethylene glycol monoethyl ether, and deionized water, with the balance made up by deionized water.
[0024] In one embodiment, the etching solution consists of components with the following mass fractions: the above-mentioned organic base (including the type and mass fraction of the above-mentioned organic base), the above-mentioned non-ionic surfactant (including the type and mass fraction of the above-mentioned non-ionic surfactant), the above-mentioned organic solvent (including the type and mass fraction of the above-mentioned organic solvent), and the above-mentioned water (including the above-mentioned water).
[0025] The second aspect of the present invention provides a preparation method of the etching solution as described in the first aspect, which includes the following steps: Mix each component in the etching solution (for example, mix at room temperature) to obtain the etching solution.
[0026] The third aspect of the present invention provides an application of the above-mentioned etching solution in selectively etching silicon in a GAA MOSFET structure.
[0027] "Room temperature" in the present invention refers to 10 - 30 °C.
[0028] On the basis of conforming to common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.
[0029] The reagents and raw materials used in the present invention are all commercially available.
[0030] The positive and progressive effects of the present invention are as follows: The germanium-silicon etching solution of the present invention has a relatively high etching rate for silicon, a relatively low etching rate for silicon-germanium alloy, silicon oxide and silicon nitride, and a good selectivity ratio of silicon / silicon-germanium alloy, and its selectivity ratio is greater than 10, which can meet the requirements of the process. Detailed implementation manners
[0031] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. For the experimental methods without specific conditions in the following examples, they are carried out according to conventional methods and conditions, or selected according to the product specifications.
[0032] 1. Preparation method
[0033] At room temperature, the components in Examples and Comparative Examples in Tables 1 and 2 are mixed evenly.
[0034] 2. Etching specimens: silicon-germanium alloy film (SiGe, 30% Ge), silicon oxide film (SiO), and silicon nitride film (SiN). Among them, the silicon oxide film and the silicon nitride film are respectively a silicon oxide film with a deposited thickness of 500 Å formed on a patterned silicon semiconductor wafer and a silicon nitride film with a deposited thickness of 500 Å formed on a patterned silicon semiconductor wafer.
[0035] 3. Etching conditions: Room temperature, stirring and soaking at 200 r / min.
[0036] 4. Etching container: Quartz cell.
[0037] Velocity measurement method: The etching specimens are respectively contacted and etched with the etching solutions prepared in the preparation examples and comparative examples. The etching temperature is room temperature and the time is 150 s. After the etching is completed, it is washed with deionized water and dried with nitrogen. Using a thin film thickness measuring device (NANO VIEW, SEMG-1000), the thickness is measured before and after etching. The etching rate is 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 silicon etching rate (Si E / R) to the silicon-germanium etching rate (SiGe E / R).
[0038] Table 1: Contents of each raw material component in the etching solution of the examples
[0039]
[0040]
[0041] In Table 1, "the balance" in each example is 100% minus the mass percentage of other components.
[0042] Table 2: Types of each raw material component in the etching solution of the examples
[0043] Example Organic base Non-ionic surfactant Organic solvent Water 1 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 2 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 3 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 4 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 5 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 6 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 7 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 8 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water 9 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water Comparative Example 1 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water Comparative Example 2 TMAH EO-PO polymer L42 Diethylene glycol monoethyl ether Deionized water
[0044] Monitor the etching rates of the etching solution on Si, SiGe, SiO, and SiN, and calculate the selectivity based on the results. The results are shown in Table 3:
[0045] Table 3:
[0046]
[0047] The experimental results show that the etching solution of the present invention has a relatively high etching rate on silicon, a relatively low etching rate on silicon-germanium alloy, silicon oxide, and silicon nitride, and the silicon / silicon-germanium alloy selectivity is greater than 10, meeting the process requirements. However, although the silicon / silicon-germanium alloy selectivity in Comparative Example 2 is also above 10, the etching rate of SiGe is relatively fast and difficult to control, and the etching rates of SiO and SiN are also too fast, easily causing defects.
Claims
1. An etching solution, characterized in that, The etching solution contains components with the following mass fractions: 1-10% organic base, 0.001-0.1% non-ionic surfactant, 5-30% organic solvent, and water, and the sum of the mass fractions of each component is 100%.
2. The etching solution according to claim 1, wherein It satisfies one or more of the following conditions: (1) The organic base is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or ammonium hydroxide; (2) The non-ionic surfactant is an EO-PO polymer; (3) The organic solvent is an alcohol solvent and / or an alcohol ether solvent; (4) The water is one or more of deionized water, distilled water, or ultrapure water.
3. The etching solution according to claim 2, wherein It satisfies one or more of the following conditions: (1) The organic base is tetramethylammonium hydroxide; (2) The non-ionic surfactant is one or more of EO-PO polymer L42, EO-PO polymer L43, or EO-PO polymer L44; (3) The organic solvent is one or more of ethylene glycol, 1,4-butanediol, glycerol, xylitol, sorbitol polyol, diethylene glycol monoether or diether, dipropylene glycol monoether or diether.
4. The etching solution according to claim 3, wherein, It satisfies (1) and / or (2): (1) The non-ionic surfactant is EO-PO polymer L42; (2) The organic solvent is one or more of diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monopropyl ether, dipropylene glycol monomethyl ether, or dipropylene glycol diethyl ether.
5. The etching solution according to claim 4, wherein, The organic solvent is diethylene glycol monoethyl ether.
6. The etching solution according to claim 1, wherein It satisfies one or more of the following conditions: (1) The mass fraction of the organic base is 1%, 3%, 5%, 7%, or 10%; (2) The mass fraction of the non-ionic surfactant is 0.005%-0.05%; (3) The mass fraction of the organic solvent is 10%-30%.
7. The etching solution according to claim 6, characterized in that It satisfies (1) and / or (2): (1) The mass fraction of the non-ionic surfactant is 0.01%; (2) The mass fraction of the organic solvent is 10%, 15%, 20%, 25%, or 30%.
8. The etching solution according to claim 1, wherein, The etching solution contains components with the following mass fractions: 1%-10% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10%-30% diethylene glycol monoethyl ether, and the balance of deionized water.
9. The etching solution according to claim 1, wherein The components of the etching solution include any combination of the following components with the following mass fractions: Combination 1: 1% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether, and deionized water, with deionized water making up the balance; Combination 2: 3% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether, and deionized water, with deionized water making up the balance; Combination 3: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether, and deionized water, with deionized water making up the balance; Combination 4: 7% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether, and deionized water, with deionized water making up the balance; Composition 5: 10% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 10% diethylene glycol monoethyl ether, and deionized water to make up the balance; Composition 6: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 15% diethylene glycol monoethyl ether, and deionized water to make up the balance; Composition 7: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 20% diethylene glycol monoethyl ether, and deionized water to make up the balance; Composition 8: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 25% diethylene glycol monoethyl ether, and deionized water to make up the balance; Composition 9: 5% tetramethylammonium hydroxide, 0.01% EO-PO polymer L42, 30% diethylene glycol monoethyl ether, and deionized water to make up the balance.
10. The etching solution according to claims 1-9, characterized in that, The etching solution consists of components with the following mass fractions and is composed of: an organic base as described in any one of claims 1-9, a non-ionic surfactant as described in any one of claims 1-9, an organic solvent as described in any one of claims 1-9, and water as described in any one of claims 1-9.