A composition suitable for the selective removal of silicon germanium from a silicon germanium / silicon stack relative to silicon for microelectronic devices

Abstract

This invention relates to a composition and its application for the selective removal of silicon-germanium from silicon-germanium / silicon stacks in microelectronic devices. The composition comprises the following components in weight fractions: 0.0001-10 wt% polyalkyleneimide; 0.001-10 wt% fluoride; 0.1-70 wt% oxidant; 0.01-50 wt% buffer composition; 0.00001-1 wt% silicon inhibitor; 0.0001-1 wt% silicon-germanium etching stabilizer; 0.0001-20 wt% defoamer; and the balance being water. The composition of this invention can be used to selectively remove silicon-germanium from microelectronic devices having silicon and silicon-germanium stacks thereon during the manufacture of microelectronic devices.

Description

Technical Field

[0001] This invention belongs to the field of electronic chemicals, and specifically relates to a composition suitable for the selective removal of silicon germanium from silicon germanium / silicon stacks relative to silicon in microelectronic devices. Background Technology

[0002] With the rapid development of semiconductor technology, chip manufacturing processes are gradually moving towards the nanoscale, which poses unprecedented challenges to the performance, power consumption, and stability of devices. Against this backdrop, GAA MOSFETs, by surrounding the channel material with the gate, achieve comprehensive control over the channel charge, significantly improving device mobility, reducing power consumption, and minimizing leakage current.

[0003] GAA (Gas-Anatomical Assembly) is an advanced semiconductor manufacturing process, and Si / SiGe heterostructures are a high-performance transistor structure used in this process. To achieve high performance and stability in transistors, precise control of the size and shape of nanowires is required, and SiGe is often used as a sacrificial layer. By precisely controlling the etching process of the SiGe sacrificial layer, precise control over the size and shape of nanowires or nanosheets can be achieved. However, the application of SiGe nanolayers in GAA processes has not been without its challenges, with etching technology becoming a key factor limiting device performance improvement. The core difficulty of SiGe nanolayer etching technology lies in precisely controlling the etching depth, shape, and uniformity to ensure that the channel material performance is not affected. Due to the difference in etching rates between SiGe and Si, and variations in the germanium content in the SiGe alloy, the selectivity of the etching process becomes difficult to control. Simultaneously, etching uniformity is also crucial to ensuring device performance and stability. Therefore, the goal of SiGe nanolayer etching technology is not only to precisely control the shape and size of the channel material, but also to optimize etching process parameters and improve etching selectivity and uniformity to meet the manufacturing requirements of high-performance semiconductor devices.

[0004] Therefore, there is a need in the art for an etching composition that provides better etching process control for etching sacrificial SiGe layers, while improving the selectivity and uniformity of SiGe nanolayer etching. Summary of the Invention

[0005] While existing chemical wet etching techniques can remove silicon and germanium to some extent, they suffer from limitations in precisely controlling the removal rate and exhibit poor selectivity relative to silicon. This is primarily due to the similar chemical properties of silicon and germanium, making it difficult to accurately select between them using traditional chemical reagents. Furthermore, existing techniques face significant challenges when processing complex three-dimensional structures, often resulting in uneven etching that negatively impacts device quality. Therefore, developing a novel, highly selective silicon-germanium etching technique is a pressing issue in the field of semiconductor manufacturing.

[0006] To address the aforementioned problems, this invention provides an etching composition suitable for the selective removal of silicon-germanium from silicon-germanium / silicon stacks in microelectronic devices. Etching is performed using a specific composition comprising: a polyalkyleneimide, a fluoride, an oxidant, a buffer composition, a silicon inhibitor, a SiGe etching stabilizer, and an antifoaming agent. This composition achieves highly selective etching of silicon-germanium, wherein the etching selectivity of silicon-germanium relative to silicon is >50, preferably >100, more preferably >150, and most preferably >200.

[0007] The main objective of the present invention has been found to be achieved by a composition comprising a silicon-germanium sacrificial layer for selective etching from a silicon-germanium / silicon stack structure in a microelectronic device, the composition comprising:

[0008] (A) Polyalkylimide, selected from:

[0009] Linear polyethyleneimine (PEI);

[0010] The preferred molecular weight of PEI is 600-7w, the more preferred molecular weight is 800-6w, and the most preferred molecular weight is 2k-2w.

[0011] Further, the amount of PEI used is 0.0001-10 wt%, preferably 0.0005-5 wt%, more preferably 0.001-2 wt%, and most preferably 0.01-1 wt%.

[0012] (B) One or more fluoride etchants containing fluorine anions, preferably selected from at least one of hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, fluoroboric acid, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride and fluorosilicates.

[0013] If the etchant is ammonium fluoride, the etchant can be about 0.001-10 wt% based on the total weight of the composition, preferably 0.002-5 wt%, more preferably 0.005-2 wt%, and most preferably 0.01-0.8 wt%.

[0014] (C) One or more oxidizing agents selected from peroxides, persulfates, percarbonates, and mixtures thereof; including but not limited to: potassium permanganate, potassium dichromate, sodium periodate, sodium perbromate, potassium persulfate, hydrogen peroxide, peracetic acid, calcium peroxide, barium peroxide, sodium percarbonate, sodium perborate, ozone, oxygen, potassium bromate, potassium chlorate, calcium hypochlorite, potassium ferrate, permanganic acid, cerium ammonium nitrate, iodine pentoxide, lead tetroxide, selenium dioxide, antimony trioxide, manganese dioxide, chromium trioxide, vanadium pentoxide, silver oxide, and combinations or mixtures thereof. Peroxides, persulfates, percarbonates, and mixtures thereof, wherein the preferred oxidizing agents are hydrogen peroxide and peracetic acid, with hydrogen peroxide being the most preferred.

[0015] Furthermore, the amount of the oxidant is about 0.1-70 wt%, preferably 1-60 wt%, more preferably 5-30 wt%, and most preferably 10-20 wt%.

[0016] (D) One or more buffer compositions suitable for buffering the pH of the composition in the range of 1 to 7, selected from sodium dihydrogen phosphate-disodium hydrogen phosphate, dipotassium hydrogen phosphate-potassium dihydrogen phosphate, acetate-ammonium acetate, citric acid-ammonium citrate, glycine-hydrochloric acid buffer systems, preferably acetate-ammonium acetate, citric acid-ammonium citrate buffer systems, and most preferably citric acid-ammonium citrate buffer systems.

[0017] Furthermore, the pH of the etching composition is preferably in the range of 1 to 7, and most preferably in the range of 3 to 5.

[0018] Further, the amount of the buffer system composition is 0.01-50 wt%, preferably 0.05-30 wt%, more preferably 0.1-20 wt%, and most preferably 0.5-10 wt%.

[0019] (E) One or more silicon inhibitors.

[0020] It was found that by using fatty alcohol polyoxyethylene ether as a silicon inhibitor, the etching selectivity in SiGe etching on Si was significantly improved compared to conventional etching compositions. This invention is derived from fatty alcohol polyoxyethylene ethers having the following formula:

[0021] RO-(CH2CH2O) n -H,

[0022] Where R represents a hydrocarbon group, which can be saturated or unsaturated. n is the addition number of the polyoxyethylene group, representing the length of the polyoxyethylene chain, which can be a different integer depending on the type of compound and the manufacturing process.

[0023] These hydrocarbon groups can be straight-chain hydrocarbon groups or branched hydrocarbon groups.

[0024] Fatty alcohol polyoxyethylene ethers (AEO series) include, but are not limited to:

[0025] -AEO-7, R is C 1 2 -C 1 6 A compound containing coconut oil alcohol with n approximately 7;

[0026] -AEO-9, R is C 1 2 -C 1 4 Compounds of secondary alkyl groups with n approximately 9;

[0027] -AEO-10, R is C 1 2 -C 1 8 Compounds with fatty alcohol groups and n approximately 10;

[0028] -AEO-15 (Pingpingjia 15), a compound in which R is a C12-C18 fatty alcohol and n is approximately 15;

[0029] -AEO-22, a compound in which R is a C12-C18 fatty alcohol and n is approximately 22;

[0030] -C12-14AEO-3, a compound in which R is a C12-C18 fatty alcohol and n is approximately 3;

[0031] -and its mixtures

[0032] Furthermore, the amount of silicon inhibitor used is 0.00001-1 wt%, preferably 0.0001-0.5 wt%, more preferably 0.0005-0.1 wt%, and most preferably 0.001-0.01 wt%.

[0033] (F) One or more SiGe etch stabilizers

[0034] It was discovered that by using a combination of silicon inhibitors and SiGe etching stabilizers, precise control over the size and shape of the sacrificial layer of SiGe nanowires or nanosheets on Si / SiGe heterostructures can be achieved, ensuring device performance and stability, and guaranteeing etching uniformity.

[0035] - Polyacrylic acid (PAA)

[0036] By using polyacrylic acid (PAA), the uniformity and selectivity of Si / SiGe stack structures are significantly increased in Si / SiGe etching compared to existing etching compositions.

[0037] Furthermore, the molecular weight of the PAA is 5,000-450,000, preferably 10,000-300,000, and most preferably 50,000-150,000.

[0038] - Polyethylene glycol (PEG)

[0039] The etching composition may optionally contain polyethylene glycol (PEG). This can further improve the uniformity and stability of SiGe etching on a-Si.

[0040] Furthermore, the PEG is preferably a non-volatile viscous liquid with a molecular weight of less than 700, and most preferably PEG-400.

[0041] Polyvinylpyrrolidone (PVP)

[0042] The etching composition may optionally contain polyvinylpyrrolidone (PVP). P This can also further improve the uniformity of SiGe etching on Si.

[0043] Furthermore, the viscosity K value of the PVP is 8-100, preferably 10-40, and most preferably 12-20.

[0044] Furthermore, the SiGe etching stabilizer is used in an amount of 0.0001-1 wt%, most preferably 0.001-0.01 wt%.

[0045] (G) One or more defoamers selected from non-silicone defoamers such as fatty alcohols, fatty acids and fatty acid esters, and amides.

[0046] Furthermore, fatty alcohol defoamers include, but are not limited to, heptanol, octanol, nonanol, decol, oleyl alcohol, coconut oil alcohol, castor oil alcohol, and mixtures thereof.

[0047] Furthermore, fatty acid defoamers include, but are not limited to, heptanoic acid, caprylic acid, nonanoic acid, decanoic acid, stearic acid, lauric acid, palmitic acid, oleic acid, myristic acid, arachidic acid, eicosapentaenoic acid, and mixtures thereof.

[0048] Furthermore, fatty acid ester defoamers include, but are not limited to, propylene glycol fatty acid esters, butanol fatty acid esters, hexanol fatty acid esters, fatty alcohol phosphate esters, glyceryl stearate, ethyl oleate, ethyl laurate, polyglycerol fatty acid esters, and mixtures thereof.

[0049] Furthermore, amide defoamers include, but are not limited to, distearyl ethylenediamine, stearic acid fatty alcohol amide, N,N-dimethyldodecylamide, lauramide propyl betaine, cocamidopropyl betaine, polyamide, polyoxyethylene alkylamide, and mixtures thereof.

[0050] Further, the amount of the defoamer is 0.0001-20wt%, preferably 0.001-15wt%.

[0051] (H) Water, in each case, is the balance of 100% by weight of the total composition.

[0052] All figures are based on the total weight of the composition, wherein the pH of the etching composition is preferably in the range of 1 to 7, and most preferably in the range of 3 to 5. And wherein in each case the sum of the wt% of each component is 100 wt%.

[0053] The present invention also provides a method for selectively etching silicon and germanium in a silicon / silicon-germanium stack using the above composition, comprising the following steps:

[0054] The composition is brought into contact with a microelectronic device containing a silicon / silicon-germanium stack at a temperature of 20°C-70°C to complete the etching of the silicon-germanium layer.

[0055] Furthermore, the contact time is <24h, preferably 1-60min.

[0056] Furthermore, the contact temperature is preferably 20-70°C, more preferably 25-60°C.

[0057] Furthermore, the SiGe / Si etching selectivity ratio is >50, preferably >100, more preferably >150, and most preferably >200.

[0058] Furthermore, the etching rate of Si is <10 Å / min, preferably <5 Å / min, and more preferably <1 Å / min.

[0059] Furthermore, the rate of silicon-germanium removal can be adjusted by increasing or decreasing etching conditions, such as component content and temperature.

[0060] Furthermore, prior to etching, the entire device structure is cleaned with an aqueous solution containing 0.5 wt% HF at room temperature for approximately 30-240 seconds, preferably 60 seconds, and more preferably 30 seconds. After etching, the etchant can be easily removed from the microelectronic device by rinsing, washing, or other removal steps. For example, the etchant can be removed by rinsing with a rinsing solution such as deionized water or an organic solvent, and / or by drying (e.g., spin drying, N2, steam drying, etc.).

[0061] 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).

[0062] 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.

[0063] The term "silicon-germanium layer" or "SiGe layer" as used in this invention corresponds to a layer comprising 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.

[0064] As defined in this invention, "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).

[0065] As defined in this invention, "low-k dielectric material" (material with a dielectric constant < 3.5) corresponds 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.

[0066] The beneficial effects of this invention are as follows:

[0067] 1. In acidic etching solutions, the addition of fatty alcohol polyoxyethylene ether as a silicon inhibitor allows it to form a passivation film on the silicon surface through chemical action, further enhancing the silicon inhibition effect and ensuring the integrity and performance of the silicon nanolayer after etching. Simultaneously, the polyoxyethylene groups possess excellent hydrophilicity and dispersibility, enabling the dispersion of particles generated during etching within the etching solution, preventing aggregation and deposition. This contributes to obtaining a smoother, flatter etched surface.

[0068] 2. Specific functional groups (such as hydroxyl and carboxyl groups) in SiGe stabilizer molecules can chemically adsorb onto atoms or ions on the surface of SiGe materials. This adsorption reduces the direct contact between active components in the etching solution (such as fluorides and oxidants) and the SiGe surface, thereby lowering the etching rate. This effectively enhances the stability and controllability of SiGe materials during etching, reducing abnormal reactions and losses of SiGe during the etching process. Simultaneously, these stabilizers improve the fluidity of the etching solution, making it easier to penetrate into the minute gaps in the structure. This contributes to achieving a more uniform and deeper etching effect, improving the precision and consistency of etching.

[0069] In summary, this invention provides an efficient, reliable, and controllable solution for silicon-germanium / silicon stack etching processes in microelectronic device manufacturing through the dual guarantee of highly selective etching and SiGe etching stability, effectively improving device yield and performance. Attached Figure Description

[0070] Figure 1 SEM images of the etched structure of the Si / SiGe25 stacked wafer using the formulation of Comparative Example 1;

[0071] Figure 2 SEM images of the etched structure of the Si / SiGe25 stacked wafer using the formulation of Example 2;

[0072] Figure 3 SEM images of the etched structure of the Si / SiGe25 stacked wafer using the formulation of Example 5. Detailed Implementation

[0073] 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.

[0074] (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.

[0075] (2) Etching conditions: 30℃, 300r / min stirring and soaking for 1-30min.

[0076] (3) Etched test pieces: Si(110), SiGe25

[0077] The formulations and test data of each embodiment and comparative example are shown in Tables 1-5.

[0078] Table 1. Etching solution formulation ratios and test data for different silicon inhibitors.

[0079]

[0080] Table 2. Etching solution formulation ratios and test data for different silicon-germanium etching stabilizers.

[0081]

[0082] Table 3. Etching rates and selectivity of SiGe with different contents

[0083]

[0084] Depend on Figure 1 (Comparative Example 1 formulation) and Figure 2(Formulation of Example 2) shows that in an acidic etching solution, the addition of fatty alcohol polyoxyethylene ether can reduce the aSi etching rate, resulting in higher SiGe / aSi selectivity. Simultaneously, the polyoxyethylene groups possess good hydrophilicity and dispersibility, enabling them to disperse particles generated during etching within the etching solution, preventing their aggregation and deposition. This contributes to obtaining a smoother, flatter etched surface. Figure 3 (Formulation of Example 5) It can be seen that adding SiGe stabilizers with specific functional groups helps to achieve a more uniform and in-depth etching effect, and improves the precision and consistency of etching.

[0085] The experimental data above show that adding compounds such as silicon inhibitors and SiGe etching stabilizers can improve etching selectivity and etching uniformity. Examples 5, 6, and 7 demonstrate that the combined use of silicon inhibitors and SiGe etching stabilizers achieves a SiGe25 / Si etching selectivity ratio as high as 230.

[0086] 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 composition suitable for the selective removal of silicon-germanium relative to silicon from a silicon-germanium / silicon stack in microelectronic devices, characterized in that, The composition comprises the following components in mass fractions: Polyalkylimide 0.0001-10 wt%; Fluorides 0.001-10 wt%; Oxidizing agent 0.1-70 wt% Buffer composition 0.01-50 wt%; Silicon inhibitor 0.00001-1 wt%; Silicon-germanium etching stabilizer 0.0001-1 wt%; Defoamer 0.0001-20wt%; The remainder is water; Polyalkyleneimide is polyethyleneimine; The fluoride is selected from at least one of hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, fluoroboric acid, tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, and fluorosilicates; the oxidant is hydrogen peroxide; The buffer composition comprises an amine-containing compound and a polyfunctional organic acid; The pH value of the composition is between 1 and 7; Silicon inhibitors are selected from fatty alcohol polyoxyethylene ethers having the following formula: RO(CH2CH2O)nH. Where R represents a hydrocarbon group, which is a saturated or unsaturated C12~C18 hydrocarbon group; the hydrocarbon group is a straight-chain hydrocarbon group or a branched hydrocarbon group; n is the addition number of ethylene oxide; The silicon-germanium etching stabilizer is polyacrylic acid, polyethylene glycol, polyvinylpyrrolidone, or combinations thereof; The defoamer is selected from one or more non-silicone defoamers among fatty alcohols, fatty acids and fatty acid esters, and amides.

2. The composition according to claim 1 for selectively removing silicon germanium from a silicon-germanium / silicon stack in a microelectronic device, characterized in that, The composition comprises the following components in mass fractions: Polyalkylene imide 0.0005-5 wt%; Fluorides 0.002-5 wt%; Oxidizing agent 1-60 wt%; Buffer composition 0.05-30 wt%; Silicon inhibitor 0.0001-0.5 wt%; Silicon-germanium etching stabilizer 0.001-0.01 wt%; Defoamer 0.001-15wt%; The remainder is water.

3. The composition according to claim 1 for selectively removing silicon-germanium from a silicon-germanium / silicon stack in microelectronic devices, characterized in that, The molecular weight of the polyethyleneimine is 600-7w.

4. The composition according to claim 1 for selectively removing silicon-germanium relative to silicon from a silicon-germanium / silicon stack in microelectronic devices, characterized in that, The molecular weight of the polyethyleneimine is 800-6w.

5. The composition according to claim 1 for selectively removing silicon-germanium relative to silicon from a silicon-germanium / silicon stack in microelectronic devices, characterized in that, The molecular weight of the polyethyleneimine is 2k-2w.

6. The composition according to claim 1 for selectively removing silicon-germanium relative to silicon from a silicon-germanium / silicon stack in microelectronic devices, characterized in that, The buffer composition is an acetate-ammonium acetate buffer system or a citric acid-ammonium citrate buffer system.

7. The composition according to claim 1 for selectively removing silicon-germanium relative to silicon from a silicon-germanium / silicon stack in microelectronic devices, characterized in that, The composition has a pH value of 3-5.

8. The use of the composition according to claims 1-7 for the selective removal of silicon-germanium from a silicon-germanium / silicon stack in microelectronic devices, characterized in that, The composition is used in processes containing Si / SiGe heterostructures, and the composition is used in a method for increasing the etching rate of silicon-germanium relative to silicon in a composite semiconductor device comprising silicon and silicon-germanium, the method comprising the following steps: A composite semiconductor device comprising a silicon-germanium / silicon stack is contacted with the composition according to any one of claims 1-7; and the semiconductor device is rinsed after the silicon-germanium has been at least partially removed, wherein the etch selectivity of silicon-germanium relative to silicon is >200.

9. The use according to claim 8, characterized in that, The method further includes the step of drying the microelectronic device; the contact step is performed at a temperature of 25°C to 70°C.

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