Use of a composition and a process for selectively etching silicon

Abstract

The present invention relates to the use of of a composition for selectively etching a silicon layer in the presence of a layer comprising a silicon germanium alloy, the composition comprising: (a) 0.1 to 5 % by weight of a pyridine of formula (E1) wherein RE1 is a substituent selected from -(XE3)s-COORE2, -(XE3)s-OH, -(XE3)s-NH2, -(XE3)s-CONH2, and -(XE3)s-CN; m is the number of substituents RE1 and is 1 or 2; XE3 is a C1 to C4 alkanediyl; RE2 is H or a C1 to C4 alkyl; and s is 0 or 1; with the exception that if m is 1 and RE1 is -(XE3)S -NH2 then RE1 must not be in the 2 position; (b) if RE1 is -(XE3)s-COOH, 0.1 to 10 % by weight of an amine of formula (E2) wherein XE1, XE2 are independently selected from a C2-C3 alkanediyl; YE is selected from NH2 and OH; n is 0, 1, 2 or 3; and (c) water.

Description

[0001] Use of a composition and a process for selectively etching silicon

[0002] The present invention relates to a composition, its use and a process for selectively etching silicon at a surface of a microelectronic device substrate, relative to etching a silicon-germanium containing material at the same surface.

[0003] Background of the Invention

[0004] Steps of preparing certain microelectronic devices, e.g., integrated circuits, may include selectively removing silicon (Si) material from a surface that contains the Si in combination with silicon-germanium (SiGe). According to certain example fabrication steps, Si may be used as a sacrificial layer in a structure that also contains SiGe. Based on such fabrication steps, advanced device structures may be prepared, such as silicon nanowires and silicon on nothing (SON) structures. Steps in these processes include epitaxial deposition of a structure of alternating layers of Si and SiGe, followed by patterning and, eventually, selective lateral etching to remove the Si layers and generate a three-dimensional silicon structure.

[0005] In certain specific methods of preparing a field effect transistors (FET) for an integrated circuit, Si and SiGe materials are deposited as layers onto a substrate, i.e. , as an "epitaxial stack" of Si and SiGe. The layers are subsequently patterned using standard techniques, such as by use of a standard lithographically generated mask. Next, a directional isotropic etch may be useful to laterally etch away the sacrificial Si material, leaving behind a SiGe nanowire or sheet structure.

[0006] By way of example, an epi-stack can be formed of alternating Si and SiGe layers, wherein the Si layers are the sacrificial layers and the SiGe layers are the channel layers. The Si layers can then be removed by selective etching, which also inadvertently recesses trenches into the bulk substrate due to the similarity of materials composing the sacrificial layers and the substrate.

[0007] To enable smaller structures within Semiconductor structures electronic industry is searching for solutions to remove selectively amorphous or crystalline silicon against SiGe layers. This is needed to realize well defined nanowire or nanosheet structures.

[0008] Another potential application of Si etching against SiGe is back-side power delivery routing (BS PDN). A backside-PDN configuration contains dense microthrough silicon vias (pTSVs) and power / ground metal stack on the backside of the die. This approach separates the PDN from a conventional signaling network of the back-end-of-the-line (BEOL) and improves power integrity and core utilization. This approach is a complete redesign of existing architectures in that both sides of the silicon have metallization layers. To achieve this, one silicon wafer is extremely thinned via CMP and chemical etching and connected to another wafer.

[0009] A number of alkaline etchants have been reported for wet etching of silicon. TMAH and ammonium hydroxide are the most commonly used silicon etchants due to their known high selectivity between Si and SiO2. However, when employed in a process to selectively etch silicon over SiGe, these etchants suffer from low horizontal etching power in releasing Si from SiGe / Si stacks. Furthermore, selectivity of these etchants for removal of Si over SiGe is usually low, i.e. <100:1.

[0010] EP 3 447 109 A1 discloses an etching composition comprising water; at least one of a quaternary ammonium hydroxide compound and an amine compound; water-miscible solvent; optionally surfactant and optionally corrosion inhibitor; and a method of using the etching composition for the selective silicon removal.

[0011] US 2019 / 0085240 A1 discloses the selective removal of Si over SiGe from a microelectronic device comprising: water; at least one of a quaternary ammonium hydroxide compound and an amine compound; water-miscible solvent; optionally surfactant and optionally corrosion inhibitor; and the method of using the etching composition for the selective silicon removal.

[0012] WO 2023 / 280637 discloses the use of a composition for selectively etching a silicon layer in the presence of a layer comprising a silicon germanium alloy, the composition comprising:

[0013] (a) 4 to 15 % by weight of an amine of formula E1

[0014] (b) water; wherein XE1, XE1, and XE1are independently selected from a chemical bond and Ci-Ce alkanediyl; YEis selected from N, CRE1, and P; and RE1is selected from H and Ci-Ce alkyl.

[0015] However, the state-of-the-art solutions are not able to fulfil all requirements since they still have at least one of the following deficiencies:

[0016] (a) a too low Si / SiGe selectivity, to remove the Si layer(s) without attacking the SiGe layer;

[0017] (b) a too low Si etch rate which leads to a long time to completely remove the Si layer(s);

[0018] (c) a too high SiGe etch rate which makes it difficult to remove the Si layer(s) while not compromising the SiGe layer(s).

[0019] It is therefore an object of the invention to increase the Si / SiGe selectivity without reducing the etch rate with respect to Si too much.

[0020] Summary of the Invention

[0021] It has now been found that the use of specific derivatives of pyridine significantly and selectively improve the Si / SiGe selectivity since the etching rate of silicon layers, particularly the etching of the SiGe layer, is selectively reduced to a larger extent than the etching rate of silicon layers, particularly crystalline, poly-crystalline or amorphous silicon layers. Therefore, one embodiment of the present invention relates to the use of a composition for selectively etching a silicon layer in the presence of a layer comprising a silicon germanium alloy, the composition comprising:

[0022] (a) 0.1 to 5 % by weight of a pyridine of formula E1 wherein

[0023] RE1is a substituent selected from -(XE3)S-COORE2, -(XE3)S-OH, -(XE3)S-NH2, -(XE3)S-CONH2, and -(XE3)S-CN; m is the number of substituents RE1and is 1 or 2;

[0024] XE3is a Ci to C4 alkanediyl;

[0025] RE2is H or a Ci to C4 alkyl; and s is O or l ; with the exception that if m is 1 and RE1is -(XE3)S-NH2 then RE1must not be in the 2 position;

[0026] (b) if RE1is -(XE3)S-COOH, 1 to 20 % by weight of an amine of formula E2 wherein

[0027] XE1, XE2are independently selected from a C2-C3 alkanediyl;

[0028] YEis selected from NH2 and OH; n is 0, 1 , 2 or 3; and

[0029] (c) water.

[0030] It was particularly surprising that the etching composition according to the invention is suited to allow for a very controlled and selective etching of silicon layers (Si), preferably of amorphous silicon (aSi) or crystalline silicon, while at the same time not or not significantly compromising silicon germanium (SiGe) layers.

[0031] Another embodiment of the present invention is a process of selectively removing a silicon layer from a surface of a microelectronic device relative to a silicon-germanium layer, the process comprising:

[0032] (a) providing a microelectronic device surface that includes the silicon layer and the layer comprising the silicon germanium alloy;

[0033] (b) providing an etching composition comprising a composition as defined above and described herein; and (c) contacting the surface with the composition for a time and at a temperature effective to selectively remove the silicon layer relative to the silicon-germanium layer.

[0034] Detailed Description of the Invention

[0035] The purpose of the etching composition is the etching of silicon (Si) layers in the presence of layers comprising or consisting of a silicon-germanium alloy (SiGe).

[0036] The composition of the subject invention comprises

[0037] (a) 0.1 to 5 % by weight of a pyridine of formula E1 wherein

[0038] RE1is a substituent selected from -(XE3)S-COORE2, -(XE3)S-OH, -(XE3)S-NH2, -(XE3)S- CONH2, and -(XE3)S-CN; m is the number of substituents RE1and is 1 or 2;

[0039] XE3is a Ci to C4 alkanediyl;

[0040] RE2is H or a Ci to C4 alkyl; and s is O or l ; with the exception that if m is 1 and RE1is -(XE3)S-NH2 then RE1must not be in 2 position (to the nitrogen atom);

[0041] (b) if RE1is -(XE3)S-COOH, 1 to 20 % by weight of an amine of formula E2 wherein

[0042] XE1, XE2are independently selected from a C2-C3 alkanediyl;

[0043] YEis selected from NH2 and OH; and n is 0, 1 , 2 or 3; and

[0044] (c) water.

[0045] Definitions

[0046] As used herein, a “silicon layer” or “Si layer" is a layer that essentially consists of elemental silicon, preferably consists of elemental silicon. It particularly includes, but is not limited to, a layer consisting of amorphous, poly-crystalline or (single-)crystalline silicon; p-doped silicon; or n-doped silicon. The etching composition is particularly useful when etching silicon, in particular amorphous silicon (aSi) or crystalline silicon (cSi) in the presence of SiGe. The term “essentially consisting of silicon” means that the silicon content in the layer is more than 90% by weight, preferably more than 95% by weight, even more preferably more than 98% by weight. When undoped silicon is used, it is particularly preferred that the silicon layer does not comprise any other elements than silicon. When n- or p-doped silicon is used, it is particularly preferred that the silicon layer is free of any other elements besides the n- or p-dopants, which may be present in an amount below 10 % by weight, preferably below 2 % by weight. Preferably, the germanium content of the silicon layer is less than 5 % by weight, preferably less than 2 % by weight, more preferably less than 1 % by weight, even more preferably less than 0.1 % by weight. Most preferably the silicon layer comprises no germanium.

[0047] As used herein, a “silicon-germanium layer” or “SiGe layer” corresponds to layers comprising or preferably consisting of silicon-germanium (SiGe) alloys known in the art and represented by the formula: SixGey, wherein x is in a range from about 0.50 to 0.90, particularly 0.60 to 0.85, and y is in a range from about 0.10 to about 0.50, particularly 0.15 to 0.40, with x+y=1.00. SiGe25 here means that y is 0.25.

[0048] As used herein, “selectively etching” (or “selective etch rate”) preferably means that upon applying a composition according to the invention to a layer comprising or consisting of a first material, in this case Si, most particularly aSi, cSi or poly-Si, in the presence of a layer comprising or consisting of a second material, in this case SiGe, the etch rate of said composition for etching the first layer is at least 150 times, preferably at least 200 times, most preferably at least 240 times the etch rate of said composition for the second layer. Depending on the substrate to be etched, other layers like SiOx, SiON or SiN should also not be jeopardized.

[0049] As used herein, “layer” means a part of a substrate that was separately disposed on the surface of a substrate and has a distinguishable composition with respect to adjacent layers.

[0050] The term “Cx” means that the respective group comprises x numbers of C atoms. The term "Cxto Cyalkyl" means alkyl with a number x to y of carbon atoms and, unless explicitly specified, includes unsubstituted linear, branched and cyclic alkyl. As used herein, “alkanediyl” refers to a diradical of linear, branched or cyclic alkanes or a combination thereof.

[0051] As used herein, “-COOH” and “-COOR” means a carboxylic acid or a carboxylic ester with R, respectively; “-OH” means a hydroxy group; “-NH2” means an amine group; “-CONH2”, means a carbamoyl group; and “-CN” means a cyano group; in doubt, it is further referred to the nomenclature in K.-H. Hellwich, R. M. Hartshorn, A. Yerin, T. Damhus, A. T. Hutton “Brief Guide to the Nomenclature of Organic Chemistry”, Version 1 .0, February 2020.

[0052] All percent, ppm or comparable values refer to the weight with respect to the total weight of the respective compound or composition except where otherwise indicated. The terms “wt%” and “% by weight” are used herein synonymously. The term “about” herein includes any values close to the specified number and the specific number itself. If not specifically specified, “close to” means plus or minus 10%, preferably plus or minus 5%, more preferably plus or minus 1 % relative to the specified number. Most preferably “about” means the exact number it refers to.

[0053] All cited documents are incorporated herein by reference.

[0054] Selectivity enhancer

[0055] The composition comprises 0.1 to 5 % by weight of a pyridine of formula E1 (also referred to herein as “selectivity enhancer”)

[0056] In formula E1 the substituent RE1may be selected from -(XE3)S-COOH, -(XE3)S-OH, -(XE3)S-NH2, - (XE3)S-CONH2, and -(XE3)S-CN. Herein XE3, if present (s= 1 ), may be a Ci to C4 alkanediyl. If s=0, which is preferred, XE3is not present and the functional groups -COOH, -OH, -NH2, -CONH2, and -CN are directly bonded to the pyridine ring structure. The one or two substituents may be in ortho, meta and / or para position to the pyridine nitrogen atom with the exception that if m is 1 and RE1is -(XE3)S-NH2 then RE1must not be in the 2 (ortho) position to the nitrogen since it was found that such compounds do not increase the Si / SiGe selectivity.

[0057] The number m of the substituents RE1may be 1 or 2, preferably 1.

[0058] In a preferred embodiment RE1is selected from -COOH.

[0059] In another preferred embodiment RE1is selected from -OH, -NH2 and -CONH2.

[0060] Preferred compounds of formula E1 are pyridine-2-carboxylic acid, pyridine-3-carboxylic acid, pyridine-4-carboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, pyridine-3,4-dicarboxylic acid, pyridine-2,3-dicarboxylic acid, methyl pyridine-2-carboxylate, methyl pyridine-3-carboxylate, methyl pyridine-4-carboxylate, ethyl pyridine-2-carboxylate, ethyl pyridine-3-carboxylate, ethyl pyridine-4-carboxylate, pyridine- 2-carboxamide, pyridine-3-carboxamide, pyridine-4-carboxamide, pyridine-3-amine, pyridine-4- amine,pyridine-2,6-diamine, pyridine-2,5-diamine, pyridine-3,5-diamine, pyridine-2,3-diamine, pyridine-3,4-diamine, pyridine-2-ol (and its tautomeric form: 1 / 7-pyridine-2-one), pyridine-3-ol, pyridine-4-ol (and its tautomeric form: 1 / 7-pyridine-4-one), 2-pyridinemethanamine, 3- pyridinemethanamine, and 4-pyridinemethanamine.

[0061] Particularly preferred examples of compounds with RE1= -COOH are:

[0062] Particularly preferred examples of compounds with RE1= -OH are

[0063] In this case the hydroxy pyridine as well as its tautomeric form may be used.

[0064] Particularly preferred examples of compounds with RE1= -NH2 are

[0065] Particularly preferred examples of compounds with RE1= -CONH2 are

[0066] Particularly preferred examples of compounds with RE1= -CN are

[0067] The selectivity enhancer may be present in an amount of from about 0.1 to about 5 % by weight. If the amount is too low, the enhancing effect is too low. A further increase of the concentration is technically possible but does not make sense for commercial reasons. Preferred concentrations are from about 0.2 to about 4 % by weight, more preferred from about 0.2 to about 3 % by weight, even more preferred from about 0.3 to about 3 % by weight. The optimal concentration window is of from about 0.5 to about 3 % by weight.

[0068] Amine

[0069] Depending on the respective selectivity enhancer used, the composition may comprise 1 to 20 % by weight of an amine of formula E2 (also referred to as “etchant”) which further supports the selective etching of silicon layers, preferably aSi, whereas the etch rate of layers comprising or consisting of SiGe, preferably of SiGe25, are still high.

[0070] The amine is optional in case only -(XE3)S-OH, -(XE3)S-NH2, -(XE3)S-CONH2, and / or -(XE3)S-CN substituents are present in the selectivity enhancer, the selectivity enhancers comprising at least one -(XE3)S-COOH group, due to its acidic character of the carboxy groups, have a zwitterionic structure which makes them insoluble in water without the aid of the amine, and therefore adding the amine is required.

[0071] Generally, the use of the amine is preferable since it enhances etching of Si more than the etching of SiGe.

[0072] In formula E1 spacer groups XE1and XE2are independently selected from a C2-C3 alkanediyl, preferably selected from 1 ,2-ethanediyl and 1-3-propanediyl.

[0073] YEmay be NH2 or OH, preferably OH. n may be 0, 1 , 2 or 3, preferably 0 or 1 , most preferably 0.

[0074] In a first preferred embodiment the amine is an alkanolamine, preferably ethanolamine.

[0075] In a second preferred embodiment the amine is a diamine, triamine, or tetramine, preferably ethylene diamine.

[0076] The amine may be present in an amount of from about 0.1 to about 15 % by weight. If the amount is too low, the enhancing effect is too low. A further increase of the concentration is technically possible but does not make sense for commercial reasons. Preferred concentrations are from about 0.3 to about 10 % by weight, more preferred from about 1 to about 8 % by weight. The optimal concentration window is of from about 2 to about 6 % by weight. Alkanolamines are well-known for reacting with carbon dioxide even from the atmosphere resulting in the formation of carbamic acids, carbamates or ammonium (bi)carbonate adducts. A small quantity of the CO2 reaction products was found to be beneficial for Si etching. To produce the CO2 reaction products, ethanolamine or the etch bath may be exposed to air or treated with pure carbon dioxide. Alternatively, the etch bath may be prepared with addition of a carbonate or hydrogen carbonate. Without limitation, useful carbonates or hydrogen carbonates are those with ammonium, Ci to Ce tetraalkylammonium, Ci to Ce tetraalkylphosphonium, alkaline metals or earth alkaline metals.

[0077] In a preferred embodiment, the carbonate or hydrogen carbonate is added in an amount from about 0.01 to about 5 % by weight, more preferred from about 0.05 to about 2 % by weight, most preferred from about 0.1 to about 1 % by weight.

[0078] The composition according to the invention may comprise one or more of the selectivity enhancers described herein.

[0079] Water

[0080] The etching compositions of the present development are aqueous-based and, thus, comprise water. Water has several functions such as, for example, to dissolve one or more components of the composition, as a carrier of the components, as an aid in the removal of residue, as a viscosity modifier of the composition, and as a diluent. Preferably, the water employed in the composition is de-ionized (DI) water. The ranges of water described in the next paragraph include all of the water in the composition from any source.

[0081] For most applications, the weight percent of water in the composition will be present in a range with start and end points selected from the following group of numbers: 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 92, 94, 96, 98, 99. Examples of the ranges of water that may be used in the composition include, for examples, from about 45 to about 99 % by weight, or about 50 to about 94% by weight of water; or from about 60 to about 99 % by weight, or from about 70 to about 96 % by weight, or from about 80 to about 96 % by weight, or from about 85 to about 99 % by weight, or from about 90 to about 99% by weight. Still other preferred embodiments of the present invention may include water in an amount to achieve the desired weight percent of the other ingredients.

[0082] Organic solvents

[0083] The etching composition may optionally comprise one or more water-miscible organic solvents.

[0084] Examples of water-miscible organic solvents that can be employed are ethylene glycol, propylene glycol, 1,4-butanediol, glycerol, tripropylene glycol methyl ether, propylene glycol propyl ether, diethylene gycol n-butyl ether (BDG), dipropylene glycol methyl ether (DPM), hexyloxypropylamine, poly(oxyethylene)diamine, dimethylsulfoxide (DMSO), tetrahydrofurfuryl alcohol, glycerol, alcohols, sulfolane, sulfoxides, diethanolamine, triethanolamine or mixtures thereof. Preferred solvents are alcohols, diols, or mixtures thereof. Most preferred solvents are C2 to Ce polyols, particularly C2 to C4 polyols, including diols, such as, for example, ethylene glycol or propylene glycol, and triols, such as, for example, glycerol.

[0085] For most applications, the amount of water-miscible organic solvent in the composition may be in a range having start and end points selected from the following list of weight percents: 0.5, 1, 5, 7, 10, 12, 15, 20, 25, 29, 30, 33, 35, 40, 44, 49.5, 50. Examples of such ranges of solvent include from about 0.5 to about 50 % by weight; or from about 1 to about 45 % by weight; or from about 1 to about 40 % by weight; or from about 0.5 % to about 30% by weight; or from about 1 to about 30 % by weight; or from about 5 to about 30 % by weight; or from about 5 to about 20 % by weight; or from about 7 to about 20 %, or from about 10 to about 30 % by weight; or from about 15 to about 25 % by weight of the composition.

[0086] In individual cases, a composition according to the invention as defined herein may further comprise as an optional additional component: One or more water-miscible organic solvents, preferably selected from the group consisting of tetra hydrofuran (THF), N-methylpyrrolidone (NMP), dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), ethanol, isopropanol, butyldiglycol, butylglycol, sulfolane (2,3,4,5-tetrahydrothiophene-1 ,1-dioxide) and mixtures thereof; more preferably selected from the group consisting of THF, NMP, DMF, DMSO, sulfolane and mixtures thereof.

[0087] The term “water-miscible organic solvent” in the context of the present invention preferably means that an organic solvent fulfilling this requirement is miscible with water at least in a 1 :1 (w / w) ratio at 20 °C and ambient pressure. Particularly, preferred are compositions according to the present invention which do not comprise one or more water-miscible organic solvents.

[0088] In a preferred embodiment, a composition according to the invention as defined herein is preferred wherein the total amount of the one or more water-miscible organic solvents is present in an amount of from about 0.1 to about 30 % by weight, preferably of from about 0.5 to about 25 % by weight, more preferably of from about 5 to about 20 % by weight, even more preferably of from about 1 to about 6 % by weight, based on the total weight of the composition.

[0089] In another preferred embodiment, a composition according to the invention as defined herein is preferred wherein the total amount of the one or more water-miscible organic solvents is present in an amount of from about 20 to about 55 % by weight, preferably of from about 25 to about 50 % by weight, more preferably of from about 30 to about 45 % by weight, based on the total weight of the composition.

[0090] In yet another preferred embodiment, a composition according to the invention as defined herein is an aqueous solution that is essentially free of organic solvents (besides the amine). “Essentially free” in this context means that the content of organic solvents is below 1 % by weight, preferably below 0.1 % by weight, even more preferably below 0.01 % by weight, most preferably below the detection limit. Most preferably the composition does not comprise any solvent besides water (and the amine).

[0091] Coordinatingagents

[0092] The etching composition may optionally comprise one or more coordinatingagents.

[0093] Preferred coordinating agents are 1,2-cyclohexylenedinitrilotetraacetic acid, 1,1 , 1 ,5, 5, 5- hexafluoro-2,4-pentane-dione, acetylacetonate, 2,2’-azanediyldiacetic acid, ethylenediamine- tetra-acetic acid, etidronic acid, methanesulfonic acid, acetylacetone, 1 , 1 , 1 -trifluoro-2,4- pentanedione, 1,4-benzoquinone, 8-hydroxyquinoline, salicyli-dene aniline; tetrachloro-1,4- benzoquinone, 2-(2-hydroxyphenyl)-benzoxazol, 2-(2-hydroxyphenyl)-benzothiazole, hydroxyquinoline sulfonic acid, sulfosalicylic acid, salicylic acid, gallic acid, pyridine, 2- ethylpyridine, 2-methoxypyridine, 3-methoxypyridine, 2-picoline, dimethylpyridine, piperidine, piperazine, ethylamine, methylamine, isobutylamine, tert-butylamine, tributylamine, dipropylamine, dimethylamine, diglycol amine, methyldiethanolamine, pyrrole, isoxazole, bipyridine, py-rimidine, pyrazine, pyridazine, quinoline, isoquinoline, indole, 1 -methylimidazole, diisopropylamine, diisobutylamine, aniline, pentamethyldiethylenetriamine, acetoacetamide, ammonium carbamate, ammonium pyrrolidinedithiocarbamate, dimethyl malonate, methyl acetoacetate, N-methyl acetoacetamide, tetramethylammonium thiobenzoate, 2, 2,6,6- tetramethyl-3,5-heptanedione, tetramethylthiuram disulfide, lactic acid, ammonium lactate, formic acid, propionic acid, gamma-butyrolactone, and mixtures thereof;

[0094] The coordinating agent may be 1,2-cyclohexylenedinitrilotetraacetic acid (CDTA) or may comprise CDTA as well as one or more of the other coordinating agents above.

[0095] A composition according to the invention as defined herein is also preferred wherein the amount of the one or more coordinating agents present is of from about 0.01 to about 4 % by weight, preferably of from about 0.02 to about 1 % by weight, more preferably of from about 0.05 to about 0.8 % by weight, based on the total weight of the composition.

[0096] In some embodiments the compositions of this invention will be free of or substantially free of any or all of the above-listed coordinating agents.

[0097] Surfactants

[0098] The composition may also further comprise one or more surfactants.

[0099] Preferred surfactants are selected from the group consisting of

[0100] (i) anionic surfactants, preferably selected from the group consisting of ammonium lauryl sulfate, fluorosurfactants, preferably selected from the group consisting of perfluorinated alkylsulfonamide salts (preferably perfluorinated, N-substituted alkylsulfonamide ammonium salts, PNAAS), perfluorooctanesulfonate, perfluorobutanesulfonate, perfluorononanoate and perfluorooctanoate; alkyl-aryl ether phosphates and alkyl ether phosphates;

[0101] (ii) zwitterionic surfactants, preferably selected from the group consisting of (3-[(3- cholamidopropyl)dimethylammonio]-1 -propanesulfonate) (“CHAPS”), cocamidopropyl hydroxysultaine (CAS RN 68139-30-0), {[3-(dodecanoylamino)propyl](dimethyl)- ammoniojacetate, phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine; and

[0102] (iii) non-ionic surfactants, preferably selected from the group consisting of glucoside alkyl ethers, glycerol alkyl ethers, cocamide ethanolamines and lauryldimethylaminoxide.

[0103] More preferred surfactants in compositions according to the invention are or comprise perfluorinated, N-substituted alkylsulfonamide ammonium salts. Preferred surfactants (E) in compositions according to the invention do not comprise metals or metal ions.

[0104] A composition according to the invention as defined herein is also preferred wherein the amount of the one or more surfactants of the surfactant present is of from about 0.0001 to about 1 % by weight, preferably of from about 0.0005 to about 0.5 % by weight, more preferably in an amount of from about 0.001 to about 0.01 % by weight, based on the total weight of the composition.

[0105] Specific surfactants for use in the compositions described herein include, but are not limited to, bis(2-ethylhexyl)phosphate, perfluoroheptanoic acid, prefluorodecanoic acid, trifluoromethanesulfonic acid, phosphonoacetic acid, dodecenylsuccinic acid, dioctadecyl hydrogen phosphate, octadecyl dihydrogen phosphate, dodecylamine, dodecenylsuccinic acid monodiethanol amide, lauric acid, palmitic acid, oleic acid, juniperic acid, 12 hydroxy stearic acid and dodecyl phosphate; polyoxyethylene lauryl ether (Emalmin NL-100 (Sanyo), Brij 30, Brij 98, Brij 35), dodecenylsuccinic acid monodiethanol amide (DSDA, Sanyo), ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol (Tetronic 90R4), polyethylene glycols (e.g., PEG 400), polypropylene glycols, polyethylene or polypropylene glycol ethers, block copolymers based on ethylene oxide and propylene oxide (Newpole PE-68 (Sanyo), Pluronic L31 , Pluronic 31 R1 , Pluronic L61 , Pluronic F-127) (Dynol 607), polyoxypropylene sucrose ether (SN008S, Sanyo), t-octylphenoxypolyethoxyethanol (Triton X100), 10-ethoxy-9,9-dimethyldecan-1 -amine (TRITON® CF-32), Polyoxyethylene (9) nonylphenylether, branched (IGEPAL CO-250), polyoxyethylene (40) nonylphenylether, branched (IGEPAL CO-890), polyoxyethylene sorbitol hexaoleate, polyoxyethylene sorbitol tetraoleate, polyethylene glycol sorbitan monooleate (Tween 80), sorbitan monooleate (Span 80), a combination of Tween 80 and Span 80, alcohol alkoxylates (e.g., Plurafac RA-20), alkyl-polyglucoside, ethyl perfluorobutyrate, 1 , 1 ,3, 3,5,5- hexamethyl-1 ,5-bis[2-(5-norbornen-2-yl)ethyl]trisiloxane, monomeric octadecylsilane derivatives such as SIS6952.0 (Siliclad, Gelest), siloxane modified polysilazane such as PP1-SG10 Siliclad Glide 10 (Gelest), silicone-polyether copolymers such as Silwet L-77 (Setre Chemical Company), Silwet ECO Spreader Momentive), and ethoxylated fluorosurfactants (ZONYL® FSO-100, ZONYL® FSN-100); cetyl trimethylammonium bromide (CTAB), heptadecanefluorooctane sulfonic acid, tetraethylammonium, stearyl trimethylammonium chloride (Econol TMS-28, Sanyo), 4-(4-diethylaminophenylazo)-1-(4-nitrobenzyl)pyridium bromide, cetylpyridinium chloride monohydrate, benzalkonium chloride, benzethonium chloride benzyldimethyldodecylammonium chloride, benzyldimethylhexadecylammonium chloride, hexadecyltrimethylammonium bromide, dimethyldioctadecylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium p-toluenesulfonate, didodecyldimethylammonium bromide, dehydrogenated tallow) dimethylammonium chloride, tetraheptylammonium bromide, tetrakis(decyl)ammonium bromide, Aliquat® 336 and oxyphenonium bromide, guanidine hydrochloride (C(NH2)3CI) or tritiate salts such as tetrabutylammonium trifluoromethanesulfonate, dimethyldioctadecylammonium chloride, dimethyldihexadecylammonium bromide and dehydrogenated tallow)dimethylammonium chloride (e.g., Arquad 2HT-75, Akzo Nobel), bromide-containing surfactants, such as, 1 -hexadecyltrimethylammonium bromide.

[0106] In some embodiments the compositions of this invention will be free of or substantially free of any or all of the above-listed surfactants.

[0107] Corrosion Inhibitors

[0108] The etching composition of the present invention may optionally include one or more corrosion inhibitors. The corrosion inhibitors, if present, may protect the silicon-germanium from etching. Examples of corrosion inhibitors include aliphatic amino carboxylic acids, for example, triethylenetetraminehexaacetic acid (TTHA), 1 ,3-diamino-2-hydroxypropane-N,N,N’,N’- tetraacetic acid (DHPTA), methyliminodiacetic acid, propylenediaminetetraacetic acid, ethylenediaminetetraacetic acid (EDTA), butylenediaminetetraacetic acid, (1 ,2-cyclohexylenediamine)- tetraacetic acid (CyDTA), diethylenetriaminepentaacetic acid (DETPA), ethylenediaminetetrapropionic acid, (hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), and nitrotriacetic acid (NTA), aminophosphonic acids, such as, N, N,N’, N’-ethylenediaminetetra(methylene- phosphonic) acid (EDTMP); carboxylic acids, such as, decanoic acid, citric acid, tartaric acid, gluconic acid, saccharic acid, glyceric acid, oxalic acid, ascorbic acid, phthalic acid, benzoic acid, mercaptobenzoic acid, maleic acid, mandelic acid, malonic acid, lactic acid and salicylic acid. Other possible corrosion inhibitors include propyl gallate, pyrogallol, quinolines, such as, 8-hydroxyquinoline, piperazines, such as, 1-(2-aminoethyl)piperazine, cysteine, and

[0109] N,N,N’,N",N"-pentamethyldiethylenetriamine (Polycat 5). Another corrosion inhibitors may include hexylamine. Some preferred corrosion inhibitors may comprise sulfur-containing groups. Other preferred corrosion inhibitors may comprise aminocarboxylic acids such as EDTA, CyDTA, quinolines, such as, 8-hydroxyquinoline, decanoic acid, 11-mercaptoundecanoic acid, piperazines, such as, 1-(2-aminoethyl)piperazine, benzimidazoles, such as, 2-mercapto-5- methylbenzimidizole, and carboxylic acids, such as, oxalic acid, decanoic acid, and ascorbic acid. More preferred corrosion inhibitors include decanoic acid, ascorbic acid, 11- mercaptoundecanoic acid, 1-(2-aminoethyl)piperazine, and 8-hydroxyquinoline.

[0110] For most applications, the amount of the corrosion inhibitors, such as, amino carboxylic acids, carboxylic acids, quinolines, or piperazines, etc, in the composition may be in a range having start and end points selected from the following list of weight percents: 0.01 , 0.05, 0.07, 0.1 ,

[0111] O.12, 0.15, 0.17, 0.2, 0.5, 1 , 1.2, 1.5, 1.7, 2, 3, 4, 6, 8, 10, 12, 15. By way of example, the corrosion inhibitors may be present in the composition from about 0.05 wt% to about 3 wt%, or from about 0.01 to about 3 wt%, or about 0.1 wt% to about 5 wt%, or from about 0.1 wt% to about 15 wt%; or from about 0.1 wt% to about 10 wt%, or from about 0.5 wt. % to about 5 wt%, or from about 0.05 wt% to about 2 wt%, or about 0.5 wt% to about 5 wt% based on the total weight of the composition.

[0112] In some embodiments the compositions of this invention will be free of or substantially free of any or all of the above-listed corrosion inhibitors, that is, the composition is free of any or all of the above-listed aminocarboxylic acids and / or carboxylic acids and / or quinolines and / or piperazines, etc..

[0113] Composition

[0114] Other commonly known components such as dyes, chemical modifiers, biocides, etc. can be included in the cleaning composition in conventional amounts, for example, amounts up to a total of about 1 or 5 or 10 % by weight of the composition to the extent that they do not adversely affect the performance of the composition.

[0115] Alternatively, the compositions of this invention may be free or substantially free of any or all of dyes, chemical modifiers, or biocides.

[0116] The etching solution composition of the present invention is typically prepared by mixing the components together in a vessel at room temperature until all solids have dissolved in the aqueous-based medium.

[0117] Generally, the pH of the composition may be in the range of from 8 to 14. In a preferred embodiment the pH of the etching composition is from about 8.5 to about 13, more preferably from about 9 to about 12 or from about 9.5 to about 12.5, most preferably from about 9.5 to about 12.

[0118] A composition according to the invention as defined herein is specifically preferred wherein the composition essentially consists of or consists of:

[0119] (a) 0.1 to 5 % by weight of a pyridine of formula E1 ;

[0120] (b) 0.3 to 10 % by weight of an amine of formula E2;

[0121] (c) 0 to 3% by weight of a surfactant;

[0122] (d) 0 to 3% by weight of a coordinating agent;

[0123] (e) rest water.

[0124] A composition according to the invention as defined herein is specifically preferred wherein the composition essentially consists of or consists of:

[0125] (a) 0.5 to 3 % by weight of a pyridine of formula E1 ;

[0126] (b) 1 to 8 % by weight of an amine of formula E2;

[0127] (c) 0 to 3% by weight of a surfactant; (d) 0 to 3% by weight of a coordinating agent;

[0128] (e) rest water.

[0129] In a particularly preferred embodiment the composition essentially consists of the pyridine, optionally the amine and water.

[0130] A composition according to the invention as defined herein is specifically preferred wherein the composition essentially consists of or consists of:

[0131] (a) 0.5 to 3 % by weight of a pyridine of formula E1 , wherein RE1is selected from -(XE3)S- COORE2, -(XE3)S-OH, -(XE3)S-NH2in 3 or 4 position, -(XE3)S-CONH2, and -(XE3)S-CN;

[0132] (b) 1 to 8 % by weight of an amine of formula E2;

[0133] (e) rest water.

[0134] A composition according to the invention as defined herein is specifically preferred wherein the composition essentially consists of or consists of:

[0135] (a) 0.5 to 3 % by weight of a pyridine of formula E1 , wherein RE1is selected from -(XE3)S-OH, - (XE3)S-NH2in 3 or 4 position, -(XE3)S-CONH2, and -(XE3)S-CN;

[0136] (e) rest water.

[0137] “Essentially” in this context means that the content of any other compounds except the specifically mentioned ones are below 1 % by weight, preferably below 0.1 % by weight, even more preferably below 0.01 % by weight, most preferably below the detection limit.

[0138] A composition according to the invention as defined herein is specifically preferred wherein the composition consists of the pyridine of formula E1 , optionally the amine of formula E2, and water as defined herein and to be defined based on the examples.

[0139] Application

[0140] In another aspect there is provided a method of selectively removing a silicon layer from a surface of a microelectronic device relative to a silicon-germanium layer, the process comprising:

[0141] (a) providing a microelectronic device surface that includes the silicon layer and the layer comprising the silicon germanium alloy;

[0142] (b) providing an etching composition comprising

[0143] (i) 0.1 to 5 % by weight of a pyridine of formula E1 wherein RE1is a substituent selected from -(XE3)S-COORE2, -(XE3)S-OH, -(XE3)S-NH2, - (XE3)S-CONH2, and -(XE3)S-CN; m is the number of substituents RE1and is 1 or 2;

[0144] XE3is a Ci to C4 alkanediyl;

[0145] RE2is H or a Ci to C4 alkyl; and s is O or l ;

[0146] (ii) if RE1is -(XE3)S-COOH, 1 to 20 % by weight of an amine of formula E2 wherein

[0147] XE1, XE2are independently selected from a C2-C3 alkanediyl;

[0148] YEis selected from NH2and OH; n is 0, 1 , 2 or 3; and

[0149] (iii) water; and

[0150] (c) contacting the surface with the composition for a time and at a temperature effective to selectively remove the silicon layer relative to the silicon-germanium layer.

[0151] In yet another aspect there is provided a method for the manufacture of a semiconductor device, comprising the step of selectively removing a silicon layer from a surface of a microelectronic device relative to a silicon-germanium layer.

[0152] In yet another aspect there is provided a method of for selectively enhancing the etch rate of silicon relative to silicon-germanium in a microelectronic device e.g. composite semiconductor device comprising silicon and silicon-germanium by etching the microelectronic device (composite semiconductor device) by using a composition as described herein.

[0153] The composition is particularly useful for selectively etching a silicon layer (Si), in the presence of a layer comprising a silicon-germanium alloy (SiGe). Such layers may be present when preparing field effect transistors (FET) for an integrated circuit. Si and SiGe materials are deposited as layers onto a substrate, i.e. , as an "epitaxial stack" of Si and SiGe. The Si layers can then be removed by selective etching, which also inadvertently recesses trenches into the bulk substrate due to the similarity of materials composing the sacrificial layers and the substrate.

[0154] Another potential application of Si etching against SiGe is back-side power delivery routing (BS PDN) as described in IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 67, 11-17. A backside-PDN configuration contains dense microthrough silicon vias (pTSVs) and power / ground metal stack on the backside of the die. This approach separates the PDN from a conventional signaling network of the back-end-of-the-line (BEOL) and improves power integrity and core utilization. This approach is a complete redesign of existing architectures in that both sides of the silicon have metallization layers. To achieve this, one silicon wafer is extremely thinned via CMP and chemical etching and connected to another wafer. The current invention describes a method for the part of the chemical etching.

[0155] It will be appreciated that it is common practice to make concentrated forms of the compositions to be diluted prior to use. For example, the compositions may be manufactured in a more concentrated form and thereafter diluted with water, at least one oxidizing agent, or other components at the manufacturer, before use, and / or during use. Dilution ratios may be in a range from about 0.1 parts diluent to 1 parts composition concentrate to about 100 parts diluent to 1 part composition concentrate.

[0156] In the use of the compositions described herein, the composition typically is contacted with the device structure for a sufficient time of from about 1 minute to about 200 minutes, preferably about 5 minutes to about 60 minutes, at temperature in a range of from about 50 °C to about 90 °C, preferably about 60 °C to about 80 °C. Such contacting times and temperatures are illustrative, and any other suitable time and temperature conditions may be employed that are efficacious to achieve the required removal selectivity. One advantage of the composition according to the present invention is its low temperature dependence of the Si / SiGe etch ratio. It was found that the Si / SiGe etch ratio is particularly advantageous at temperatures above room temperature but should be well below the boiling point of water.

[0157] Following the achievement of the desired etching action, the composition can be readily removed from the microelectronic device to which it has previously been applied, e.g., by rinse, wash, or other removal step(s), as may be desired and efficacious in a given end use application of the compositions of the present invention. For example, the device may be rinsed with a rinse solution including deionized water, an organic solvent, and / or dried (e.g., spin-dry, N2, vapor-dry etc.).

[0158] It may be useful to clean the blanket wafer surfaces (removal of oxide) for about 10 s to about 120 s with an aqueous solution containing about 0.1% to 5% by weight HF at room temperature.

[0159] Preferably the Si, etch rates of the compositions according to the invention are 2000 A / min or more, more preferably 3000 A / min or more. Preferably the SiGe, particularly SiGe25 etch rates of the compositions according to the invention are 30 A / min or below, more preferably 25 A / min or below. Preferably the etch rate of the silicon layer is at least 100, preferably 120, even more preferably 150, even more preferably preferably 200, most preferably more than 240 times faster than the etch rate of the layer comprising silicon-germanium (Si / SiGe selectivity).

[0160] After the contacting step is an optional rinsing step. The rinsing step may be carried out by any suitable means, for example, rinsing the substrate with de-ionized water by immersion or spray techniques. In preferred embodiments, the rinsing step may be carried out employing a mixture of de-ionized water and an organic solvent such as, for example, isopropanol. After the contacting step and the optional rinsing step is an optional drying step that is carried out by any suitable means, for example, isopropanol (I PA) vapor drying, heat, or by centripetal force.

[0161] The following examples shall further illustrate the present invention without restricting the scope of this invention.

[0162] Examples

[0163] General Procedures and Substrates

[0164] The following substrates were used as coupons of about 2.5 x 2.5 cm: SALSA III available from IMEC and described e.g. in Solid State Phenomena, Vol. 314, pp 71-76. The substrate comprised several stacked SiGe and aSi layers. SALSA 3 layer build up from top to bottom: SiO2 (50nm) - SiN (50nm) - SiO2 (5nm) - Si (25nm) - SiGe (25nm) - Si (20nm) - SiGe (20nm) - Si (15nm) - SiGe (15nm) - Si (10nm) - SiGe (10nm) - Si (5nm) - SiGe (5nm) - Si<100> Wafer (ca. 0.70mm). All SiGe layer contained 25% by weight of Germanium.

[0165] Blanket wafer coupons comprised of crystalline Si (500 nm) on a SiGe layer. Blanket Wafer Coupons comprised of SiGe25 (50 nm) on Si.

[0166] Etch bath preparation:

[0167] The etchant was prepared by adding the respective pyridine and, if applicable, the amine in the specified amounts into DI water. The etchant was transferred into a plastic beaker equipped with a thermostat.

[0168] Pre-conditioning of ethanolamine:

[0169] For the examples comprising ethanolamine provided in the following paragraphs, 0.1 -0.5 wt% of NH4HCO3 were added to the etchant at least 30 min before the tests were perforemed.

[0170] Pre-etching:

[0171] UPW and 1 wt% hydrogen fluoride were filled into two plastic beakers. Each coupon (SiGe25, poly-Si) was pre-etched in 1 wt% hydrogen fluoride for 60 s, then dipped into UPW for 2-3 s and dried with compressed air.

[0172] The etchant was set to 40 °C + / - 0.5 °C. Once the temperature was reached, the poly-Si or SiGe25 wafer coupons were submerged into the etchant. Each coupon was etched separately for 0.25 to 20 minutes, depending on substrate thickness, under stirring, subsequently rinsed with DI water and dried.

[0173] The resulting thickness was determined by spectroscopic ellipsometry. Example 1

[0174] Compositions comprising the specified amount of the pyridine in water were prepared as described above. The etching rates were determined by ellipsometry by comparing the layer thickness before and after etching. The results are also depicted in table 1.

[0175] Table 1

[0176] The results depicted in Table 1 show that the amine substitutent increases the Si / SiGe selectivity to more than 350 and by more than a factor of 10 compared to unsubstituted pyridine.

[0177] Example 2

[0178] Compositions comprising 2 wt% ethanolamine, 1 wt% of the selectivity enhancer, 0.3 wt% of NH4HCO3, and rest water were prepared as described above. The etching rates were determined by ellipsometry by comparing the layer thickness before and after etching. The results are depicted in table 2.

[0179] Table 2

[0180] The results depicted in Table 2 show that the combination of an alkanolamine in combination with substituted pyridines increase the Si / SiGe selectivity to more than 240. Meta and para monosubstituted pyridine amines, ortho, meta and para monosubstituted pyridine carboxylic acids, and para monosubstituted hydroxy pyridines show the best results.

[0181] The comparison of example 2.10 with example 1.4 also shows that the addition of ethanolamine further increases the Si / SiGe selectivity. Example s

[0182] Compositions comprising the specified amount of several amines, 1 wt% of the selectivity enhancer, 0.3 wt% of NH4HCO3 for examples comprising ethanolamine, and rest water was prepared. The etching rates were determined by ellipsometry by comparing the layer thickness before and after etching. The results are depicted in table 3.

[0183] Table 3

[0184] The results depicted in Table 3 show that ethylene diamine, dielethylene triamine and particularly ethanolamine show a high Si / SiGe selectivity. Even low amounts of pyridine derivatives of 1 wt% are sufficient for the selectivity enhancing effect.

Claims

Claims1 . The use of a composition for selectively etching a silicon layer in the presence of a layer comprising a silicon germanium alloy, the composition comprising:(a) 0.1 to 5 % by weight of a pyridine of formula E1whereinRE1is a substituent selected from -(XE3)S-COORE2, -(XE3)S-OH, -(XE3)S-NH2, -(XE3)S- CONH2, and -(XE3)S-CN; m is the number of substituents RE1and is 1 or 2;XE3is a Ci to C4 alkanediyl;RE2is H or a Ci to C4 alkyl; and s is O or l ; with the exception that if m is 1 and RE1is -(XE3)S-NH2 then RE1must not be in the 2 position;(b) if RE1is -(XE3)S-COOH, 0.1 to 15 % by weight of an amine of formula E2whereinXE1, XE2are independently selected from a C2-C3 alkanediyl;YEis selected from NH2 and OH; n is 0, 1 , 2 or 3; and(c) water.

2. The use according to anyone of the preceding claims, wherein m is 1 .

3. The use according to anyone of claims 1 or 2, wherein RE1is selected from -COOH.

4. The use according to anyone of claims 1 or 2, wherein RE1is selected from -OH, -NH2 and-CONH2.

5. The use according to claim 4, further comprising 0.01 to 10 % by weight of an amine of formula E1whereinXE1, XE2are independently selected from a C2-C3 alkanediyl;YEis selected from NH2 and OH; and n is 0, 1 , 2 or 3.

6. The use according to anyone of the preceding claims, wherein XE1is selected from ethane-1,2-diyl, propane-1, 3-diyl, and propane-1 ,2-diyl.

7. The use according to anyone of the preceding claims, wherein the amine is selected from ethanolamine, ethylene diamine, and diethylene triamine.

8. The use according to anyone of the preceding claims, wherein the amine is present in the composition in an amount of from 1 to 8 % by weight, preferably from 2 to 6 % by weight.

9. The use according to anyone of the preceding claims, wherein the pyridine is present in the composition in an amount of from 0.2 to 3 % by weight, preferably from 0.5 to 2 % by weight.

10. The use according to anyone of the preceding claims, wherein the composition further comprises a carbonate or a hydrogencarbonate.

11. The use according to anyone of the preceding claims, wherein the composition essentially consists of:(a) 0.1 to 5 % by weight of a pyridine of formula E1 ;(b) 0 to 15 % by weight of an amine of formula E2;(c) 0 to 3% by weight of a surfactant;(d) 0 to 3% by weight of a coordinating agent;(e) 0 to 5% by weight of CO2, a carbonate or a hydrogencarbonate;(f) rest water.

12. The use according to anyone of the preceding claims, wherein the composition essentially consists of:(a) 0.1 to 5 % by weight of a pyridine of formula E1 ;(b) 0.1 to 15 % by weight of an amine of formula E2;(c) 0 to 3% by weight of a surfactant;(d) 0 to 3% by weight of a coordinating agent;(e) 0 to 5% by weight of CO2, a carbonate or a hydrogencarbonate;(f) rest water.

13. The use according to anyone of the preceding claims, wherein the composition has a pH of 9 to 13, particularly from 9.5 to 12.5.

14. A process of selectively removing a silicon layer from a surface of a microelectronic device relative to a silicon-germanium layer, the process comprising:(a) providing a microelectronic device surface that includes the silicon layer and the layer comprising the silicon germanium alloy;(b) providing an etching composition comprising(i) 0.1 to 5 % by weight of a pyridine of formula E1whereinRE1is a substituent selected from -(XE3)S-COORE2, -(XE3)S-OH, -(XE3)S- NH2, -(XE3)S-CONH2, and -(XE3)S-CN; m is the number of substituents RE1and is 1 or 2;XE3is a Ci to C4 alkanediyl;RE2is H or a Ci to C4 alkyl; and s is O or l ; with the exception that if m is 1 and RE1is -(XE3)S-NH2then RE1must not be in the 2 position;(ii) if RE1is -(XE3)S-COOH, 0.01 to 10 % by weight of an amine of formula E2whereinXE1, XE2are independently selected from a C2-Ca alkanediyl;YEis selected from NH2and OH; n is 0, 1 , 2 or 3; and(iii) water; and(c) contacting the surface with the composition for a time and at a temperature effective to selectively remove the silicon layer relative to the silicon-germanium layer.

15. A process for the manufacture of a semiconductor device, comprising the step of selectively removing a silicon layer from a surface of a microelectronic device relative to a silicon-germanium layer according to claim 14.

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