Selective etching liquid and selective etching method

Abstract

The invention provides a selective etching solution and a selective etching method, and belongs to the field of semiconductor integrated circuit manufacturing, the selective etching solution comprises an etching agent, an additive and a solvent, the additive comprises a polymer monomer, the polymer monomer comprises a polymerization group and a surface binding group, and the surface binding group comprises a surface binding group and a surface binding group. The polymeric group comprises a conjugated pi bond between a carbon atom and a heteroatom, and the surface binding group is selectively attached to the surface of the non-etching material in the etching material and the non-etching material. The additive introduced into the selective etching liquid can be quickly polymerized on the surface of the non-etching material in situ to form a polymer protection film, so that the surface of the non-etching material is selectively protected in the etching material and the non-etching material, and the non-etching material is prevented from being etched and damaged by an etching agent; and therefore, selective etching of the small-size semiconductor device is realized.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor integrated circuit manufacturing, and particularly relates to a selective etching solution and a selective etching method. Background Art

[0002] With the continuous reduction of dimensions and the increasing requirements for the speed and functionality of ultra-high density integrated circuits, conventional planar metal oxide semiconductor field effect transistors (MOSFETs) are facing more and more challenges, such as the scaling of the gate oxide thickness and the electrostatic control of the gate electrode on the channel region. At present, the proposed 3D-structured semiconductor devices have further reduced the device dimensions on the premise of ensuring stable electronic control.

[0003] 3D semiconductor devices such as Fin FETs, 3D NANDs or GAA FETs, etc., have structural characteristics of multi-layer stacking, high aspect ratio and complex geometry. During their formation, etching and cleaning need to be carried out on the side surfaces of the devices and even deep buried surfaces. For example, in GAA FETs, the channel regions of the upper ring gate structure are basically nanowires formed by side etching. The nanowire channels usually have a thickness (or diameter) of dozens of nanometers (nm) or less, and have an unrestricted length. The nanowire channels are usually horizontally suspended between source regions and drain regions of larger sizes, and are anchored to the substrate.

[0004] At present, 3D semiconductor device structures are usually fabricated on a bulk silicon substrate using compatible CMOS technology. For example, a typical manufacturing method for forming a channel region in a GAAFET involves the stacking (epitaxial-stacking) of sacrificial layers epitaxially grown between channel layers on top of the bulk substrate. The sacrificial layer and the channel layer are composed of two different materials, so that selective etching can remove the sacrificial layer to form a ring gate structure.

[0005] However, as Figure 1 and Figure 2 shown, when wet etching sacrificial layers with smaller and smaller dimensions in 3D structures, it is easy to cause the loss of non-etched materials and result in a higher roughness of the etched surface. Therefore, it is necessary to design a selective etching solution and a selective etching method to improve the above technical problems. Summary of the Invention

[0006] The present invention provides a selective etching solution and a selective etching method, which are applicable to selective etching between conventional semiconductor materials such as silicon, silicon nitride, silicon oxide, and silicon germanium.

[0007] To achieve the above and other related objectives, the present invention provides a selective etching solution, which includes an etchant, an additive, and a solvent. Among them, the additive includes a polymer monomer, and the polymer monomer includes a polymerization group and a surface-binding group. The polymerization group contains a conjugated π bond between a carbon atom and a heteroatom, and the surface-binding group selectively adheres to the surface of the non-etched material among the etched material and the non-etched material.

[0008] In an example of the present invention, the polymerization group is an acrylic acid group, an acrylic acid derivative group, a benzotriazole group, a benzotriazole derivative group, an aniline group, an aniline derivative group, an acrylonitrile group, an acrylonitrile derivative group, a phosphazene group, or a phosphazene derivative group.

[0009] In an example of the present invention, when the non-etched material is silicon nitride or silicon and the etched material is silicon oxide, the surface-binding group is a lipophilic group, and the lipophilic group includes at least one of a hydrocarbon group, an aryl group, an ester group, a polyoxypropylene group, and a long-chain perfluoroalkyl group.

[0010] In an example of the present invention, when the non-etched material is silicon oxide and the etched material is silicon nitride or silicon, the surface-binding group is a hydrophilic group, and the hydrophilic group includes at least one of a hydroxyl group, an amino group, a carboxyl group, an alcohol group, an amide group, and a sulfonic acid group.

[0011] In an example of the present invention, when the non-etched material is silicon and the etched material is silicon germanium, the selective etching solution further includes a pH regulator, the pH value of the selective etching solution is 2 to 4.5, and the surface-binding group of the additive is a cationic group, and the cationic group includes at least one of an amino group, an amine group, a quaternary ammonium group, and a nitrogen-containing heterocyclic group.

[0012] In an example of the present invention, when the non-etched material is silicon germanium and the etched material is silicon, the selective etching solution further includes a pH regulator, the pH value of the selective etching solution is 2 to 4.5, and the surface-binding group of the additive is an anionic group, and the anionic group includes at least one of a fluoride ion group, a sulfonic acid group, a sulfate ester group, and a phosphate ester group.

[0013] In an example of the present invention, in the selective etching solution, the mass content of the additive is 2% to 10%, the mass content of the etchant is 2% to 70%, and the balance is the solvent.

[0014] In an example of the present invention, the etchant includes at least one of hydrofluoric acid, acetic acid, hydrogen peroxide, nitric acid, phosphoric acid, phosphorous acid, pyrophosphoric acid, sulfurous acid, sulfuric acid, ammonia water (ammonium hydroxide), hydroxylamine, and hydroxylamine derivatives.

[0015] In an example of the present invention, the solvent includes water or a mixture of water and a water-miscible solvent, and the water-miscible solvent is selected from at least one of ethylene glycol, propylene glycol, butyl diglycol, 1,4-butanediol, tripropylene glycol methyl ether, dipropylene glycol monomethyl ether, propylene glycol propyl ether, diethylene glycol n-butyl ether, hexyloxypropylamine, polyoxyethylene diamine, dimethyl sulfoxide, tetrahydrofurfuryl alcohol, glycerol, alcohol, sulfoxide, and sulfolane.

[0016] The present invention also provides a selective etching method, which includes the following steps: Bring a semiconductor device containing an etching material and a non-etching material into contact with the selective etching solution described in any of the above examples, and cause an additive in the selective etching solution to in-situ polymerize on the surface of the non-etching material to form a polymer film; clean the selective etching solution on the surface of the semiconductor device, and remove the polymer film on the surface of the non-etching material; dry the semiconductor device.

[0017] The present invention provides a selective etching solution and a selective etching method. By introducing an additive into the selective etching solution, the polymer monomer in the additive has the characteristics of spontaneously adhering to the surface of the non-etching material and initiating copolymerization, and can quickly in-situ polymerize on the surface of the non-etching material to form a polymer protective film when the selective etching solution contacts the semiconductor device, so as to selectively protect the surface of the non-etching material among the etching material and the non-etching material to avoid the non-etching material being etched and damaged by the etchant, and further realize the selective etching of small-sized semiconductor devices. Description of the Drawings In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments can be obtained based on these drawings.

[0018] Figure 1 It is a cross-sectional electron micrograph of a ring gate structure formed by conventional wet etching; Figure 2 It is a cross-sectional structure schematic diagram of a ring gate structure formed by conventional wet etching; Figure 3 It is a schematic diagram of the working mechanism of the additive of the selective etching solution in an embodiment of the present invention; Figure 4 It is a schematic diagram of the working mechanism of the additive of the selective etching solution in another embodiment of the present invention; Figure 5 It is a schematic diagram of the working mechanism of the additive of the selective etching solution in yet another embodiment of the present invention; Figure 6Schematic diagram of the working mechanism of the additive in the selective etching solution in another embodiment of the present invention; Figure 7 Schematic diagram of the selective etching process of the selective etching solution in an embodiment of the present invention. Detailed implementation manners

[0019] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for the purpose of describing specific specific implementation manners, rather than for limiting the protection scope of the present invention. The test methods without specific conditions noted in the following embodiments are usually carried out according to conventional conditions or according to the conditions recommended by each manufacturer.

[0020] For simplicity, only some numerical ranges are explicitly disclosed herein. Each point or single numerical value between the range endpoints is included in this range. Thus, each point or single numerical value can be used as its own lower or upper limit and combined with any other point or single numerical value or combined with other lower or upper limits to form a range not explicitly recorded.

[0021] In this article, terms such as "multiple", "multiple types", "multiple times", etc., unless otherwise specifically defined, refer to a quantity greater than 2 or equal to 2. For example, "one or more types" means one type or greater than or equal to two types. "Further", "even further", "especially", etc. are used for descriptive purposes and represent differences in content, but should not be construed as limiting the protection scope of the present invention.

[0022] In this article, unless otherwise specified, "%" all represents mass percentage content.

[0023] In this article, a substituent refers to an atom or atomic group substituted on the main chain or ring in an organic compound. They can replace a certain hydrogen atom or other atom in the molecule and affect the chemical and physical properties of the molecule. The type and position of the substituent have an important impact on the reactivity, polarity, solubility and other properties of the molecule.

[0024] Number of heteroatoms: In organic chemistry, non-carbon atoms are collectively referred to as heteroatoms. The most common heteroatoms are nitrogen atoms, sulfur atoms and oxygen atoms.

[0025] On the one hand, the present invention provides a selective etching solution. The additive introduced in the selective etching solution can rapidly undergo in-situ polymerization on the surface of the non-etching material under preset triggering conditions. The polymer film formed by the additive on the surface of the non-etching material can selectively protect the non-etching material among the etching material and the non-etching material, so as to avoid the non-etching material being etched and damaged by the etchant, thereby realizing the selective etching of small-sized semiconductor devices. Based on the characteristics of the etching solution for selective etching of small-sized semiconductor devices in the present invention, the etching solution can be applied to the process of manufacturing a gate all-around structure on an electronic device.

[0026] The above-mentioned selective etching solution includes a solvent, an etchant, and an additive. The solvent is used to dissolve the etchant and the additive. The solvent can serve as a carrier for the etchant and the additive, and in some embodiments, it also provides a surface attachment environment for the additive on the surface of the non-etching material. The additive is used to selectively polymerize on the surface of the non-etching material among the etching material and the non-etching material to form a polymer film, so as to avoid the surface of the non-etching material being etched and damaged by the etchant. The etchant then selectively etches the etching material that is not protected by the polymer film among the etching material and the non-etching material.

[0027] The additive includes a polymer monomer. The polymer monomer can selectively adhere to the surface of the non-etching material among the etching material and the non-etching material and undergo a copolymerization reaction under preset triggering conditions, thereby rapidly forming a polymer film on the surface of the non-etching material to avoid the surface of the non-etching material exposed during the etching process being damaged by the etching solution.

[0028] In the present invention, the polymer monomers in the additive include a surface binding group A and a polymerization group B. The surface binding group A and the polymerization group B can be directly connected by a chemical bond (such as chemical formula A-B), or can be connected by an intermediate group C (such as chemical formula A-C-B). The intermediate group C can be, for example, an ether bond (-O-), a carbon-oxygen bond (-C-O-), a carbon-carbon bond (-C-C-), or a combination of multiple such groups. The surface binding group A and the polymerization group B are located at both ends of the polymer monomer respectively. The surface binding group A at one end of the polymer monomer spontaneously adheres to the surface of the non-etching material; the polymerization group B at the other end of the polymer monomer contains a conjugated π bond between a carbon atom and a heteroatom. The conjugated π bond in the polymerization group B is broken under a preset initiation condition and undergoes a copolymerization reaction with each other, so that the polymer monomers adhering to the surface of the non-etching material copolymerize to form a polymer film, thereby protecting the surface of the non-etching material. Among them, the preset initiation condition can be adaptively adjusted according to the polymerization group. The preset initiation condition can be ultraviolet radiation, ultrasonic radiation, or the use of an initiator. The initiator can be, for example, ammonium sulfate ((NH4)2SO4), hydrazine sulfate (N2H6SO4), etc. The dosage of the initiator in the selective etching solution is 0.5% - 1.5% of the total mass of the selective etching solution. For example, the addition amount of the initiator can be 0.5%, 0.7%, 1%, 1.2%, or 1.5%.

[0029] The polymerization group B of the polymer monomer is selected from at least one of an acrylic group, an acrylic derivative group, a benzotriazole group, a benzotriazole derivative group, an aniline group, an aniline derivative group, an acrylonitrile group, an acrylonitrile derivative group, a phosphazene group, or a phosphazene derivative group.

[0030] The surface binding group A of the polymer monomer can be adaptively selected according to the surface difference characteristics of the non-etching material relative to the etching material, and will be described in detail with the following specific examples.

[0031] As Figure 3 shown, in some embodiments, when the non-etching material in the selective etching interface is silicon nitride or silicon, and the etching material is a silicon oxide compound, that is, when the selective etching solution selects to etch the silicon oxide compound (such as SiO2 or SiO x , 0 < x < 2) between silicon nitride or silicon, the surface binding group in the additive polymer monomer is a lipophilic group. Among them, the surface of the silicon oxide compound is hydrophilic, the surfaces of silicon nitride and silicon are hydrophobic. The surface binding group in the polymer monomer is repelled by the surface of the silicon oxide compound due to its lipophilicity and aggregates and adheres to the hydrophobic surface of silicon nitride or silicon. The polymer monomers adhering to the hydrophobic surface of silicon nitride or silicon copolymerize to form a polymer protective film under subsequent initiation to avoid damage to the surface of silicon nitride or silicon by the etchant, and realize the selective etching of the silicon oxide compound in the silicon oxide compound and silicon nitride or silicon by the selective etching solution.

[0032] It should be noted that in the above embodiments, the surface binding group can be any conventional lipophilic group. For example, the surface binding group can be selected from alkyl groups, aryl groups, ester groups, polyoxypropylene groups or long-chain perfluoroalkyl groups.

[0033] As Figure 4 shown, in some other embodiments, when the non-etching material in the selective etching interface is silicon oxide and the etching material is silicon nitride or silicon, that is, when the selective etching solution selects to etch silicon nitride or silicon in silicon oxide and silicon nitride or silicon, the surface binding group in the additive polymer monomer is a hydrophilic group. Among them, the surfaces of silicon nitride and silicon are hydrophobic, and the surface of silicon oxide is hydrophilic. The surface binding group in the polymer monomer is likely to aggregate and adhere to the hydrophilic surface of silicon oxide due to its hydrophilicity. The polymer monomer adhering to the hydrophilic surface of silicon oxide copolymerizes to form a polymer protective film under subsequent initiation to prevent the surface of silicon oxide from being damaged by the etchant, realizing the selective etching of silicon nitride or silicon in silicon oxide and silicon nitride or silicon by the selective etching solution.

[0034] It should be noted that in the above embodiments, the surface binding group can be any conventional hydrophilic group. For example, the surface binding group can be selected from hydroxyl groups, amine groups, carboxyl groups, alcohol groups, amide groups or sulfonic acid groups.

[0035] In addition, in the above embodiments, a pH regulator can also be added to the selective etching solution. The pH regulator is used to form an acidic environment in the selective etching solution to enhance the surface binding characteristics of the surface of the non-etching material during the selective etching process, so as to better promote the additive to adhere and form a film on the surface of the non-etching material. The pH regulator can be selected from at least one of isopropanolamine, cyclopropylamine, diisopropylamine, isobutylamine, ethanolamine, triethylamine, N-ethylethanolamine, inorganic bases sodium hydroxide, potassium hydroxide, ammonia water and diammonium hydrogen phosphate. The mass content of the pH regulator in the selective etching solution is 1% - 5%, for example, it can be 1%, 2%, 3%, 4% or 5%.

[0036] As Figure 5As shown, in some other embodiments, when the non-etching material in the selective etching interface is silicon and the etching material is silicon-germanium, that is, when the selective etching solution selects to etch silicon-germanium in silicon-germanium and silicon, an acid-base value regulator is further added to the selective etching solution. The acid-base value regulator is used in an appropriate amount to make the pH value of the selective etching solution be any value in the range of 2 to 4.5. The surface-binding group in the additive polymer monomer is a cationic group. Since the surfaces of silicon-germanium and silicon will exhibit different surface potentials in an environment where the pH value is less than 4.5. Among them, when in contact with the selective etching solution with a pH value less than 4.5, the surface of silicon-germanium shows a positive electric potential, and the surface of silicon shows a negative electric potential. The surface-binding group in the polymer monomer is positively charged and adheres to the negative electric surface of silicon through electrostatic force, and copolymerizes on the negative electric surface of silicon under subsequent initiation to form a polymer protective film, thereby avoiding damage to the silicon surface by the etchant in silicon-germanium and silicon, and realizing the selective etching of silicon-germanium in silicon-germanium and silicon.

[0037] It should be noted that in the above embodiments, the surface-binding group can be any conventional cationic group. For example, the surface-binding group can be selected from amino group, amine group, quaternary ammonium group or nitrogen-containing heterocyclic group.

[0038] As Figure 6 shown, in still some other embodiments, when the non-etching material in the selective etching interface is silicon-germanium and the etching material is silicon, that is, when the selective etching solution selects to etch silicon in silicon-germanium and silicon, an acid-base value regulator is further added to the selective etching solution. The acid-base value regulator is used in an appropriate amount to make the pH value of the selective etching solution be any value in the range of 2 to 4.5. The surface-binding group in the additive polymer monomer is an anionic group. Since the surfaces of silicon-germanium and silicon will exhibit different surface potentials in an environment where the pH value is less than 4.5. Among them, when in contact with the selective etching solution with a pH value less than 4.5, the surface of silicon shows a negative electric potential, and the surface of silicon-germanium shows a positive electric potential. The surface-binding group in the polymer monomer is negatively charged and adheres to the positive electric surface of silicon-germanium through electrostatic force, and copolymerizes on the positive electric surface of silicon-germanium under subsequent initiation to form a polymer protective film, thereby avoiding damage to the silicon-germanium surface by the etchant in silicon-germanium and silicon, and realizing the selective etching of silicon in silicon-germanium and silicon.

[0039] It should be noted that in the above embodiments, the surface-binding group can be any conventional anionic group. For example, the surface-binding group can be selected from fluoride ion group, sulfonic acid group, sulfate group or phosphate group.

[0040] In addition, in the above embodiments, the acid-base value regulator can be selected from at least one of isopropanolamine, cyclopropylamine, diisopropylamine, isobutylamine, ethanolamine, triethylamine, N-ethylethanolamine, inorganic bases sodium hydroxide, potassium hydroxide, ammonia water and diammonium hydrogen phosphate.

[0041] The masses of the components in the selective etching solution satisfy the following relationships: the mass content of the additive in the selective etching solution is any value within 2% - 10%, for example, the mass content of the additive can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%; the mass content of the etchant in the selective etching solution is any value within 2% - 70%, for example, the mass content of the etchant can be 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%; the remaining part in the selective etching solution is the solvent.

[0042] In the selective etching solution, the etchant can be adaptively selected from conventional etchants according to the material to be etched. In some embodiments, the etchant is selected from at least one of hydrofluoric acid, acetic acid, hydrogen peroxide, nitric acid, phosphoric acid, phosphorous acid, pyrophosphoric acid, sulfurous acid, sulfuric acid, ammonia water (ammonium hydroxide), hydroxylamine and hydroxylamine derivatives. That is, the etchant can be any one of the above - listed types, for example, it can be hydrofluoric acid, acetic acid, hydrogen peroxide, nitric acid, phosphoric acid, phosphorous acid, pyrophosphoric acid, sulfurous acid, sulfuric acid, ammonia water, hydroxylamine or hydroxylamine derivatives; the etchant can also be a combination of any multiple of the above - listed types, for example, it can be a combination of hydrofluoric acid and nitric acid, or a combination of hydrofluoric acid and sulfuric acid, or a combination of hydrofluoric acid and phosphoric acid, or a combination of nitric acid and phosphoric acid, or a combination of boric acid and phosphoric acid, or a combination of nitric acid, nitric acid and acetic acid, or a combination of hydrofluoric acid, hydrogen peroxide and acetic acid, or a combination of hydrofluoric acid, nitric acid and sulfuric acid, or a combination of hydrofluoric acid, nitric acid, sulfuric acid and acetic acid. It should be noted that when the etchant is a combination, the ratio between the components in the combination is not limited and can be mixed in any ratio.

[0043] In some embodiments, the solvent includes at least water. In the present invention, water acts in various ways. For example, water is used to dissolve one or more components of the etchant and the additive composition. In addition to being a carrier for the components, water can also be an aid for removing etching residues, and can also be a viscosity regulator and a diluent for the composition. Optionally, the water used in the solvent is deionized water (DIW).

[0044] In other embodiments, the solvent includes, in addition to water, a water - miscible solvent, and the water - miscible solvent is selected from at least one of ethylene glycol, propylene glycol, butyl diglycol, 1,4 - butanediol, tripropylene glycol methyl ether, dipropylene glycol monomethyl ether, propylene glycol propyl ether, diethylene glycol n - butyl ether, hexyloxypropylamine, polyoxyethylene diamine, dimethyl sulfoxide, tetrahydrofurfuryl alcohol, glycerol, alcohol, sulfoxide, sulfolane.

[0045] Such as Figure 7As shown, the present invention further provides a selective etching method in another aspect. This selective etching method is used to selectively etch a predetermined etching material in a semiconductor device, and is particularly suitable for etching and manufacturing a gate-all-around structure on a semiconductor device. The selective etching method includes the following steps: S1. Bring a semiconductor device containing an etching material and a non-etching material into liquid-phase contact with the selective etching liquid described in any of the above embodiments, and cause an additive in the selective etching liquid to in-situ polymerize on the surface of the non-etching material to form a polymer film; S2. Clean the selective etching liquid on the surface of the semiconductor device and remove the polymer film on the surface of the non-etching material; S3. Dry the semiconductor device.

[0046] In step S1, any suitable contact method can be adopted, such as dipping or spraying. During the contact between the semiconductor device and the selective etching liquid in step S1, the temperature of the selective etching liquid is 25°C to 100°C, and can be optionally 30°C to 50°C; the contact time can be set to any suitable time according to the etching depth, and the contact time is usually 1 minute to about 60 minutes.

[0047] In step S1, the way to initiate the copolymerization reaction of the additive can be any conventional initiation method, such as ultraviolet radiation, ultrasonic radiation or adding an initiator; among them, the initiator can be, for example, conventional initiators such as ammonium sulfate ((NH4)2SO4), hydrazine sulfate (N2H6SO4), etc. The addition amount of the initiator in the selective etching liquid is 0.5% - 1.5% of the total mass of the selective etching liquid. For example, the addition amount of the initiator can be 0.5%, 0.7%, 1%, 1.2% or 1.5%.

[0048] In step S2, any conventional cleaning method can be used to rinse the surface of the semiconductor device, such as rinsing the substrate carrying the semiconductor device with deionized water through dipping or spraying techniques. In one example, a mixture of deionized water and an organic solvent (such as isopropyl alcohol) can be selected to rinse the semiconductor device.

[0049] In step S2, any conventional method can be used to remove the polymer film formed on the surface of the non-etching material, such as using a mixture of sulfuric acid and hydrogen peroxide for wet de-polymerization to remove the polymer film on the surface of the non-etching material; or using oxygen plasma etching to specifically remove the polymer film on the surface of the non-etching material.

[0050] In step S3, any conventional method can be used to dry the semiconductor device, such as heating and drying, spin drying, nitrogen blowing or isopropyl alcohol vapor drying.

[0051] The technical solutions of the present invention will be described in detail below through several specific examples and comparative examples. Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by conventional methods in the art.

[0052] Example 1 This example provides a selective etching solution, which is used to selectively etch silicon oxide in silicon oxide and silicon nitride or silicon. The selective etching solution includes an etchant, an additive, and a solvent. The solvent is a composition of water and ethylene glycol, and the volume ratio of water to ethylene glycol is 1:1. The etchant includes hydrofluoric acid, nitric acid, and acetic acid, and the volume ratio of hydrofluoric acid, nitric acid, and acetic acid is 2:7:1. The additive is octadecyl acrylate, the polymerization group in octadecyl acrylate is an acrylic group, and the surface binding group in octadecyl acrylate is an octadecyl group. In the selective etching solution, the mass content of the etchant is 30%, the mass content of the additive is 10%, and the balance is the solvent.

[0053] Example 2 This example provides a selective etching solution with the same system as that in Example 1, which is also used to selectively etch silicon oxide in silicon oxide and silicon nitride or silicon. The difference between the selective etching solution in this example and that in Example 1 is that the additive is N-ethyl perfluorooctane sulfonamide acetic acid, the polymerization group in N-ethyl perfluorooctane sulfonamide acetic acid is an aniline group, and the surface binding group in N-ethyl perfluorooctane sulfonamide acetic acid is a perfluorooctadecyl group.

[0054] Example 3 This example provides a selective etching solution, which is used to selectively etch silicon nitride or silicon in silicon oxide and silicon nitride or silicon. The selective etching solution includes an etchant, an additive, and a solvent. The solvent is a composition of water and ethylene glycol, and the volume ratio of water to ethylene glycol is 1:1. The etchant includes hydrofluoric acid. The additive is 2-hydroxyethyl acrylate, the polymerization group in 2-hydroxyethyl acrylate is an acrylic group, and the surface binding group in 2-hydroxyethyl acrylate is a hydroxyl group.

[0055] Example 4 This example provides a selective etching solution with the same system as that in Example 3, which is also used to selectively etch silicon nitride or silicon in silicon oxide and silicon nitride or silicon. The difference between the selective etching solution in this example and that in Example 3 is that the additive is 4-aminotoluene-2-sulfonic acid, the polymerization group in 4-aminotoluene-2-sulfonic acid is an aniline group, and the surface binding group in 4-aminotoluene-2-sulfonic acid is a sulfonic acid group.

[0056] Example 5 This embodiment provides a selective etching solution, which is used to selectively etch silicon in silicon germanium and silicon. The selective etching solution includes an etchant, an additive, and a solvent. The solvent is a composition of water and ethylene glycol, and the volume ratio of water to ethylene glycol is 1:1; the etchant includes hydrofluoric acid; the additive is sodium dodecyl sulfonate, the polymer group in sodium dodecyl sulfonate is an acrylic group, and the surface binding group in sodium dodecyl sulfonate is a sulfonic acid group. In the selective etching solution, the mass content of the etchant is 30%, the mass content of the additive is 10%, and the balance is the solvent.

[0057] Example 6 This embodiment provides a selective etching solution with the same system as that in Example 5, and this selective etching solution is also used to selectively etch silicon in silicon germanium and silicon. The difference between the selective etching solution in this embodiment and that in Example 5 is that the additive is 4-aminotoluene-2-sulfonic acid, the polymer group in 4-aminotoluene-2-sulfonic acid is an aniline group, and the surface binding group in 4-aminotoluene-2-sulfonic acid is a sulfonic acid group.

[0058] Example 7 This embodiment provides a selective etching solution with the same system as that in Example 5, and this selective etching solution is also used to selectively etch silicon in silicon germanium and silicon. The difference between the selective etching solution in this embodiment and that in Example 5 is that the additive is 4-sulfobenzotriazole, the polymer group in 4-sulfobenzotriazole is a benzotriazole group, and the surface binding group in 4-sulfobenzotriazole is a sulfonic acid group.

[0059] Example 8 This embodiment provides a selective etching solution, which is used to selectively etch silicon germanium in silicon germanium and silicon. The selective etching solution includes an etchant, an additive, and a solvent. The solvent is a composition of water and ethylene glycol, and the volume ratio of water to ethylene glycol is 1:1; the etchant includes hydrofluoric acid; the additive is acrylamide, the polymer group in acrylamide is an acrylic group, and the surface binding group in acrylamide is an amino group. In the selective etching solution, the mass content of the etchant is 30%, the mass content of the additive is 10%, and the balance is the solvent.

[0060] Example 9 This embodiment provides a selective etching solution with the same system as that in Example 8, and this selective etching solution is also used to selectively etch silicon germanium in silicon germanium and silicon. The difference between the selective etching solution in this embodiment and that in Example 8 is that the additive is 3-aminopropionitrile, the polymer group in 3-aminopropionitrile is an acrylonitrile group, and the surface binding group in 3-aminopropionitrile is an amino group.

[0061] In summary, the present invention provides a selective etching solution and a selective etching method. The additive introduced into the selective etching solution can rapidly in-situ polymerize on the surface of the non-etching material to form a polymer protective film, thereby selectively protecting the surface of the non-etching material between the etching material and the non-etching material to avoid the non-etching material being etched and damaged by the etchant, and further realizing the selective etching of small-sized semiconductor devices.

[0062] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A selective etching solution, characterized in that, Comprising: A solvent, said solvent comprising water or a mixture of water and a water-miscible solvent; An etchant; An additive, including a polymer monomer, said polymer monomer including a polymerization group and a surface-binding group, the polymerization group containing a conjugated π bond between a carbon atom and a heteroatom, and the surface-binding group being selected to adhere to the surface of the non-etching material among the etching material and the non-etching material.

2. The selective etching solution according to claim 1, characterized in that, The polymerization group is an acrylic group, an acrylic derivative group, a benzotriazole group, a benzotriazole derivative group, an aniline group, an aniline derivative group, an acrylonitrile group, an acrylonitrile derivative group, a phosphazene group or a phosphazene derivative group.

3. The selective etching solution according to claim 1, characterized in that, When the non-etching material is silicon nitride or silicon and the etching material is a silicon oxide compound, the surface-binding group is a lipophilic group, and the lipophilic group includes at least one of a hydrocarbon group, an aryl group, an ester group, a polyoxypropylene group and a long-chain perfluoroalkyl group.

4. The selective etching solution according to claim 1, characterized in that, When the non-etching material is a silicon oxide compound and the etching material is silicon nitride or silicon, the surface-binding group is a hydrophilic group, and the hydrophilic group includes at least one of a hydroxyl group, an amine group, a carboxyl group, an alcohol group, an amide group and a sulfonic acid group.

5. The selective etching solution according to claim 1, characterized in that, When the non-etching material is silicon and the etching material is silicon-germanium, the selective etchant further includes a pH regulator, the pH value of the selective etchant is 2 to 4.5, and the surface-binding group of the additive is a cationic group, and the cationic group includes at least one of an amino group, an amine group, a quaternary ammonium group and a nitrogen-containing heterocyclic group.

6. The selective etching solution according to claim 1, characterized in that, When the non-etching material is silicon-germanium and the etching material is silicon, the selective etchant further includes a pH regulator, the pH value of the selective etchant is 2 to 4.5, and the surface-binding group of the additive is an anionic group, and the anionic group includes at least one of a fluoride ion group, a sulfonic acid group, a sulfate group and a phosphate group.

7. The selective etching solution according to claim 1, characterized in that, In the selective etchant, the mass content of the additive is 2% to 10%, the mass content of the etchant is 2% to 70%, and the balance is the solvent.

8. The selective etching solution according to claim 1, characterized in that, The etchant includes at least one of hydrofluoric acid, acetic acid, hydrogen peroxide, nitric acid, phosphoric acid, phosphorous acid, pyrophosphoric acid, sulfurous acid, sulfuric acid, ammonia water, hydroxylamine and hydroxylamine derivatives.

9. The selective etching solution according to claim 1, characterized in that, The water-miscible solvent is selected from at least one of ethylene glycol, propylene glycol, butyl diglycol, 1,4-butanediol, tripropylene glycol methyl ether, dipropylene glycol monomethyl ether, propylene glycol propyl ether, diethylene glycol n-butyl ether, hexyloxypropylamine, polyoxyethylene diamine, dimethyl sulfoxide, tetrahydrofurfuryl alcohol, glycerol, alcohol, sulfoxide, sulfolane.

10. A selective etching method, characterized in that, Comprising: Bringing a semiconductor device comprising an etching material and a non-etching material into contact with the selective etchant according to any one of claims 1 to 9, and causing the additive in the selective etchant to in-situ polymerize on the surface of the non-etching material to form a polymer film; Washing the selective etchant on the surface of the semiconductor device and removing the polymer film on the surface of the non-etching material; Drying the semiconductor device.

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