Silicon-selective etching liquid composition

Abstract

The present invention relates to a composition for selectively etching silicon on a surface exposed with a metal film and silicon. According to the present invention, a selective etching ratio of silicon can be improved on a semiconductor surface exposed with a metal film and silicon.

Description

Technical Field

[0001] The present invention relates to an acidic etching solution composition for selectively etching silicon on a surface exposed with a metal film and silicon (Si). Background Technology

[0002] Tungsten (W) is used as a representative plug metal in the semiconductor field.

[0003] Meanwhile, silica-based etching solutions include etching substances such as hydrofluoric acid and oxidizing substances such as nitric acid and sulfuric acid.

[0004] In semiconductor fabrication, acidic etchants, particularly during bulk silicon etching, suffer from increased defect rates due to silicon's low selectivity for tungsten films. Specifically, the non-selective etching of metals like tungsten can lead to defects in subsequent processes, such as exposed underlying patterns or short circuits. These issues limit the application of acidic etchants in processes like semiconductor packaging and through-silicon vias (TSVs).

[0005] Therefore, there is a need to investigate a composition that has a very low etching rate on metal films and can selectively etch only silicon. Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The present invention aims to provide a composition that improves the silicon etching selectivity of metal films.

[0008] means for solving problems

[0009] To address the aforementioned problems, the present invention provides a silicon-selective etching solution composition comprising fluorine compounds, sulfuric acid, nitrososulfuric acid, nitric acid, and organic amine compounds.

[0010] According to one embodiment, the aforementioned fluorine compound may include one or more of the following: hydrofluoric acid, ammonium bifluoride, sodium fluoride, potassium fluoride, aluminum fluoride, fluoroboric acid, ammonium fluoride, sodium bifluoride, potassium bifluoride, and ammonium tetrafluoroborate.

[0011] According to one embodiment, the above-mentioned organic amine compound may include polyethyleneimine (PEI), octylamine, triazole, poly(propylene imine) (PPI), pentaethylene hexamine, N,N'-bis(2-aminoethyl)-1,3-propanediamine, N-(2-aminoethyl)-1,3-propanediamine, N-(3-aminopropyl)-1,3-propanediamine, spermine, and spermidine. The following are one or more of the following: rmidine, 1,4-bis(3-aminopropyl)piperazine, 1-(2-aminoethyl)piperazine, tris(2-aminoethyl)amine, branched or dendrite polyamidoamine (PAMAM), dendritic polypropylenimine (DAB-am-16), poly(L-lysine) (PLL), and chitosan.

[0012] According to one embodiment, the molecular weight of the above-mentioned organic amine compound can be from Mw300 to 20000.

[0013] According to one embodiment, the etching rate of silicon can be 2000 angstroms / minute or higher, and the silicon etching selectivity for the metal film can be 50 or higher.

[0014] According to another embodiment, the present invention provides a method for preparing a silicon selective etching solution composition, comprising the step of mixing 0.5 to 15 wt% of a fluorine compound, 0.5 to 95 wt% of sulfuric acid, 0.1 to 20 wt% of nitrososulfuric acid, 0.1 to 3 wt% of nitric acid, and 0.001 to 10 wt% of an organic amine compound.

[0015] Specific details of other embodiments of the present invention are included in the following detailed description.

[0016] The effects of the invention

[0017] According to the present invention, the selective etching ratio of silicon can be improved on semiconductor surfaces exposed with metal films and silicon. Detailed Implementation

[0018] This invention can be modified in various ways and has various embodiments, which will be illustrated and described in detail below. However, this is not intended to limit the invention to specific implementations, but should be understood to include all modifications, equivalents, and substitutions contained within the spirit and scope of the invention. In describing the invention, detailed descriptions of related known technologies will be omitted if it is determined that such detailed descriptions may obscure the gist of the invention.

[0019] Unless otherwise stated in this specification, the expression "to" will be used as an expression that includes the corresponding value. Specifically, for example, the expression "1 to 2" means not only including 1 and 2, but also including all values ​​between 1 and 2.

[0020] In the semiconductor field, silicon is oxidized into a silicon oxide film by oxidants and oxidizing agents. The oxidized silicon oxide film has a mechanism for contact with etchants and being etched. During silicon etching, to minimize underlying patterning and wiring short-circuit defects, the selective etching amount of silicon onto the metal film needs to be considered.

[0021] The present invention aims to improve the selective etching effect of silicon on metal films by providing a specific combination of additive structures.

[0022] The silicon selective etching solution composition according to embodiments of the present invention will be described in more detail below.

[0023] Specifically, the present invention provides a silicon selective etching solution composition comprising fluorine compounds, sulfuric acid, nitrososulfuric acid, nitric acid, and organic amine compounds.

[0024] Fluorine compounds are compounds that dissociate to form F, which has a strong affinity for silicon. - or HF 2-The fluorine compound serves to etch the silicon oxide film. The types of fluorine compounds can include one or more of the following: hydrofluoric acid (HF), ammonium bifluoride (ABF, NH4HF2), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF3), fluoroboric acid (HBF4), ammonium fluoride (NH4F), sodium bifluoride (NaHF2), potassium bifluoride (KHF2), and ammonium tetrafluoroborate (NH4BF4). Specifically, for example, it can include one or more of hydrofluoric acid, ammonium fluoride, and ammonium bifluoride.

[0025] The content of fluorine compounds can be from 0.5% to 15% by weight, for example, more than 1% by weight, more than 2% by weight, more than 3% by weight, and can be less than 10% by weight or less than 5% by weight. And within this content range, it is suitable for etching silicon films relative to metal films.

[0026] Sulfuric acid can act as a silicon dioxide. The sulfuric acid content can be from 0.5% to 95% by weight, for example, more than 50% by weight, more than 60% by weight, more than 70% by weight, more than 80% by weight, and for example, less than 95% or less than 90%.

[0027] Nitrosylsulfuric acid acts as a catalyst for silicon oxidation. The content of nitrosylsulfuric acid can be from 0.1% to 20% by weight, for example, more than 0.5% by weight, more than 1% by weight, more than 2% by weight, and for example, less than 15% by weight, less than 10% by weight, less than 5% by weight.

[0028] This invention effectively oxidizes silicon by comprising sulfuric acid and nitrosylsulfuric acid, respectively. In particular, the inclusion of nitrosylsulfuric acid allows for the maintenance of a high concentration of oxidizing agents in the etching solution, thereby facilitating silicon oxidation.

[0029] Nitric acid acts as a catalyst for silicon oxidation and produces oxidized substances. The content of nitric acid can be from 0.1% to 3% by weight, for example, more than 0.3% by weight, or for example, less than 2% by weight or less than 1% by weight.

[0030] Organic amine compounds can control the silicon etching selectivity for metals. These compounds can include cationic additives, such as polyethyleneimine (PEI), octylamine, triazole, poly(propylene imine) (PPI), pentaethylenehexamine, N,N'-bis(2-aminoethyl)-1,3-propanediamine, N-(2-aminoethyl)-1,3-propanediamine, N-(3-aminopropyl)-1,3-propanediamine, and spermine (sp...). The following are included: ermine, spermidine, 1,4-bis(3-aminopropyl)piperazine, 1-(2-aminoethyl)piperazine, tris(2-aminoethyl)amine, branched or dendrite polyamidoamine (PAMAM), dendritic polypropylenimine (DAB-am-16), poly(L-lysine) (PLL), and chitosan. Specifically, for example, it may include one or more of polyethyleneimine, poly(propylene amine), octylamine, 1,2,4-triazole, and 1,2,3-triazole.

[0031] According to one embodiment, when the above-mentioned organic amine compound is polyethyleneimine, the molecular weight can be from Mw300 to 20000, for example, it can be Mw400 or more, Mw500 or more, Mw600 or more, and for example, it can be Mw15000 or less, Mw12000 or less, Mw10000 or less.

[0032] Furthermore, the content of organic amine compounds can be from 0.001 to 10% by weight, for example, it can be more than 0.005% by weight, more than 0.01% by weight, more than 0.03% by weight, and for example, it can be less than 5% by weight, less than 3% by weight, or less than 1% by weight.

[0033] This invention improves the selective etching rate of silicon onto metal films by incorporating organic amine compounds. Specifically, because organic amine compounds can be physically adsorbed onto the metal surface, they reduce the oxidation rate of the metal. Therefore, the silicon selective etching ratio of the metal film can be effectively improved by reducing the etching rate of the metal film.

[0034] According to one embodiment, when processing a substrate whose surface is simultaneously exposed to a metal film and silicon according to the present invention, the etching rate of silicon can be 2000 angstroms / minute or more, for example, 2500 angstroms / minute or more, 3000 angstroms / minute or more, and for example, 10000 angstroms / minute or less, 5000 angstroms / minute or less.

[0035] Furthermore, the silicon (Si) etching selectivity ratio for the metal film (e.g., tungsten (W) film) can be above 50, above 100, or for example, below 1000, below 600, or below 500.

[0036] According to one embodiment, in this invention, the metal film may include one or more of tungsten (W), titanium nitride (TiN), titanium (Ti), gold (Au), molybdenum (Mo), nickel (Ni), palladium (Pd), and platinum (Pt), specifically, for example, it may include tungsten.

[0037] According to one embodiment, the remaining amount may include water to make the total weight of the composition 100% by weight. The water used is not particularly limited; deionized water may be used, preferably deionized water with a resistivity of 18 MΩ / cm or higher, indicating the degree of ion removal from the water.

[0038] According to one embodiment, the composition of the present invention may further include any additives used in conventional etching solution compositions to improve etching performance. For example, it may also include one or more selected from the group consisting of stabilizers, surfactants, chelating agents, antioxidants, corrosion inhibitors, and mixtures thereof.

[0039] Stabilizers can be etching stabilizers, including those used to suppress side reactions or byproducts that may occur in the etching composition or the object being etched due to unwanted reactions.

[0040] Surfactants can be added to improve the wettability of the etching solution composition, enhance the foaming properties of the additives, and increase the solubility of other organic additives. The surfactant can be one or more selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. The amount of surfactant added can be from 0.0005% to 5% by weight relative to the total weight of the etching solution composition; preferably, it can be from 0.001% to 2% by weight relative to the total weight of the composition. When the content of the surfactant is less than 0.0005% by weight relative to the total weight of the etching solution composition, no effect can be expected. When the content of the surfactant is 5% by weight or more, solubility problems or process problems due to excessive foaming may occur.

[0041] Chelating agents can be added to improve the solubility of the etching solution composition for metallic impurities or to form a uniform etched surface. 0.1 to 5% by weight of the chelating agent can be added relative to the total weight of the composition; preferably, it can be an organic acid having both carboxyl and hydroxyl groups.

[0042] Antioxidants and corrosion inhibitors may be included to protect metals or metal compounds used as materials for semiconductor devices, etc. As described above, any antioxidants and corrosion inhibitors commonly used in the art may be used without limitation; for example, pyrrole (azole) compounds may be included, but are not limited thereto, and may be added at a rate of 0.01 to 10% by weight relative to the total weight of the composition.

[0043] The etching method using the composition of the present invention can be implemented by commonly used methods and is not particularly limited thereto.

[0044] Embodiments of the present invention will be described in detail below to enable those skilled in the art to readily implement them. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein.

[0045] Examples and Comparative Examples

[0046] Silicon-selective etching solution compositions were prepared according to the compositions in Table 1. Each composition included water to bring the total weight of the composition to 100% by weight.

[0047] Table 1

[0048]

[0049] Experimental Example 1: Evaluation of Etching Rate

[0050] To confirm the etching rate of each composition, evaluation substrates with tungsten (W) and silicon exposed on their surfaces were cut into 20×20 mm pieces, and the thickness and weight of each substrate were measured. The evaluation substrates were immersed in the etching solution compositions according to the various embodiments and comparative examples for 15 minutes in a thermostatic bath maintained at 25°C for etching. After etching, the substrates were washed with ultrapure water and completely dried using a drying device to remove any remaining etching solution composition and moisture. The weight of the dried substrates was then measured, the weight change before and after evaluation was calculated, and the etching rate was measured using the following mathematical formula 1.

[0051] [Mathematical Expression 1]

[0052] (Initial substrate thickness × weight reduction rate) / processing time = etching rate

[0053] The results are shown in Table 2.

[0054] Table 2

[0055]

[0056] As shown in Table 2, in the comparative examples, it was confirmed that the silicon etching selectivity for tungsten was lower than that for Si / W, below 20. In particular, in comparative examples 3 and 4, silicon was hardly etched.

[0057] Conversely, in all embodiments, excellent silicon etch speed and selectivity were confirmed, with silicon etch speeds exceeding 3500 angstroms / min and Si / W ratios exceeding 100.

[0058] Therefore, the etching solution composition according to the present invention improves the silicon etching selectivity of the metal film by reducing the etching rate of the metal film.

[0059] The foregoing has described specific aspects of the present invention in detail. It will be apparent to those skilled in the art that these specific techniques are merely preferred embodiments, and the scope of the present invention is not limited thereto. Those skilled in the art can make various modifications and variations within the scope of the present invention based on the above description. Therefore, the essential scope of the present invention will be defined by the appended claims and their equivalents.

Claims

1. A silicon selective etching solution composition for selectively etching silicon on a semiconductor surface exposed with a metal film and silicon, wherein, include: Relative to the total weight of the composition, 0.5 to 5% by weight of fluorine compounds; 80 to 95% sulfuric acid; 1 to 5% by weight of nitrososulfuric acid; 0.1 to 2% by weight of nitric acid; and 0.01 to 3% by weight of organic amine compounds, The aforementioned fluorine compounds include one or more of hydrofluoric acid, ammonium hydrogen fluoride, sodium fluoride, potassium fluoride, aluminum fluoride, fluoroboric acid, ammonium fluoride, sodium hydrogen fluoride, potassium hydrogen fluoride, and ammonium tetrafluoroborate. The organic amine compound includes one or more of polyethyleneimine, octylamine, triazole, polypropyleneimine, and dendritic polypropyleneimine-hexadecylamine. The etching rate of silicon is above 2000 angstroms / min, and the etching selectivity of silicon relative to the metal film is above 50.

2. The silicon selective etching solution composition according to claim 1, wherein, The weight-average molecular weight (Mw) of the organic amine compound is between 300 and 20,000.

3. A method for preparing a silicon selective etching solution composition, wherein the silicon selective etching solution composition is used to selectively etch silicon on a semiconductor surface exposed with a metal film and silicon, wherein, The method includes the step of mixing 0.5 to 5% by weight of a fluorine compound, 80 to 95% by weight of sulfuric acid, 1 to 5% by weight of nitrososulfuric acid, 0.1 to 2% by weight of nitric acid, and 0.01 to 3% by weight of an organic amine compound. The aforementioned fluorine compounds include one or more of hydrofluoric acid, ammonium hydrogen fluoride, sodium fluoride, potassium fluoride, aluminum fluoride, fluoroboric acid, ammonium fluoride, sodium hydrogen fluoride, potassium hydrogen fluoride, and ammonium tetrafluoroborate. The organic amine compound includes one or more of polyethyleneimine, octylamine, triazole, polypropyleneimine, and dendritic polypropyleneimine-hexadecylamine. The silicon selective etchant composition is used to selectively etch silicon on a semiconductor surface exposed with a metal film and silicon, with an etch rate of 2000 angstroms / min or higher for silicon and an etch selectivity of 50 or higher for silicon relative to the metal film.

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