Composition, its use and a process for selectively etching silicon-germanium layers

Abstract

The invention relates to a composition for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content, wherein the first germanium content is higher than the second germanium content, the composition comprising: (a) 0.1 to 10 % by weight of an oxidizing agent, wherein the oxidizing agent is a peroxide; (b) 1 to 14 % by weight of an etchant comprising a source of fluoride ions; (c) 0.0005 to 4 % by weight of an Si protecting agent (d) 0 % or 0.001 to 3 % by weight of an SiOx protecting agent; and (e) water.

Description

[0001] Composition, its use and a process for selectively etching silicon -germanium layers

[0002] The present invention relates to a composition, its use and a process for selectively etching silicon -germanium layers at a surface of a microelectronic device substrate, relative to etching a silicon material or a silicon-germanium material that has a lower germanium content 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 - germanium (SiGe) material from a surface that contains the SiGe in combination with silicon (Si). According to certain example fabrication steps, SiGe may be used as a sacrificial layer in a structure that also contains silicon. 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 SiGe 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 SiGe material, leaving behind a silicon nanowire or sheet structure.

[0006] In other applications SiGe having a low Ge content may have to be etched against SiGe having a higher Ge content.

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

[0008] US 2009 / 0078982 A1 discloses selectively etching of a sacrificial layer of SiGe using an etchant including hydrofluoric acid (HF), nitric acid (HNO3), and an a-hydroxy carboxylic acid.

[0009] WO 2022 / 043165 discloses a composition for selectively etching a layer comprising a silicon germanium alloy (SiGe) in the presence of a layer comprising silicon, the composition comprising 5 to 15 % by weight of an oxidizing agent, 5 to 20 % by weight of an etchant comprising a source of fluoride ions, 0.001 to 3 % by weight of an acetylenic hydroxy compound, and water. WO 2023 / 161058 discloses the use of 0.001 to 3 % by weight of an additional selectivity enhancer of formula

[0010] However, there is still a need for providing additives that allow a selective etching of SIGe layers.

[0011] It is therefore an object of the invention to keep or even increase the SiGe / Si etching selectivity or the selectivity of etching a SIGe with a higher Ge content against SIGe with a lower Ge content.

[0012] Summary of the Invention

[0013] It has now been found that the use of specific epoxy compounds and their hydrolysis derivatives significantly and selectively improves the SiGe / Si selectivity or SIGe with a higher Ge content against SIGe with a lower Ge content.

[0014] Therefore, one embodiment of the present invention is a composition for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content, wherein the first germanium content is higher than the second germanium content, the composition comprising:

[0015] (a) 0.1 to 10 % by weight of an oxidizing agent, wherein the oxidizing agent is selected from a peroxide;

[0016] (b) 1 to 14 % by weight of an etchant comprising a source of fluoride ions;

[0017] (c) 0.0005 to 4 % by weight of an Si protecting agent of formula P1 or of formula P2 or of formula P3

[0018] (d) 0 % or 0.001 to 3 % by weight of an SIOXprotecting agent of formula S41 or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by cocondensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more

[0019] (e) water; wherein is selected from

[0020] Ci to C10 alkyl, or

[0021] RP2is selected from H, and a Ci to Ce alkyl,

[0022] RP3is selected from

[0023] (a) Ci to C10 alkyl;

[0024] (b) Ce to C12 aryl or alkylaryl; or

[0025] (c) Ce to C12 arylalkyl;

[0026] RP4is selected from RP3or H;

[0027] XP1is a divalent spacer selected from Ci to Ce alkanediyl;

[0028] XP2is a divalent group selected from a Ci to Ce alkanediyl;

[0029] RS41is Ci to Ce alkyl which may be unsubstituted or substituted by -NRS61RS62or -OR561;

[0030] RS42, RS43are independently selected from Ci to Ce alkoxy and Ci to Ce alkyl which both may be unsubstituted or substituted by -NRS61RS62or -OR561; RS51, RS52are independently selected from Ci to Ge alkyl which may be unsubstituted or substituted by -NRS61RS62or -OR561;

[0031] RS61, RS62are independently selected from H and Ci to Ce alkyl;

[0032] Xs1is a Ci to Cs alkanediyl; and m is an integer of from 1 to 30.

[0033] It was particularly surprising that the etching composition according to the invention is suited to allow for a very controlled and selective etching of layers comprising or consisting of SiGe alloys, e.g. SiGe25 or SiGe40 layers, even of thin or ultra-thin layers comprising germanium (“Ge layers”), particularly layers comprising or consisting of SiGe alloys, while at the same time not or not significantly compromising Si layers, particularly amorphous or crystalline silicon layers, most particularly amorphous silicon layers or SiGe layers having a lower Ge content. Particularly the selectivity of SiGe / SiOx, SiGe / SiON and / or SiGe / SiN etching, particularly SiGe / SiOxcan be kept or even improved.

[0034] Another embodiment of the present invention is a concentrate for preparing a composition for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content, wherein the first germanium content is higher than the second germanium content, the composition comprising:

[0035] (b) 1 to 14 % by weight of an etchant comprising a source of fluoride ions;

[0036] (c) 0.0005 to 4 % by weight of an Si protecting agent of formula P1 or of formula P2 or of formula P3

[0037] (d) 0 % or 0.001 to 3 % by weight of an SiOxprotecting agent of formula S41 or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by co- condensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more

[0038] (e) water; wherein is selected from

[0039] Ci to C10 alkyl, or

[0040] RP2is selected from H, and a Ci to Ce alkyl,

[0041] RP3is selected from

[0042] (a) Ci to C10 alkyl;

[0043] (b) Ce to C12 aryl or alkylaryl; or

[0044] (c) Ce to C12 arylalkyl;

[0045] RP4is selected from RP3or H;

[0046] XP1is a divalent spacer selected from Ci to Ce alkanediyl;

[0047] XP2is a divalent group selected from a Ci to Ce alkyl;

[0048] RS41is Ci to Ce alkyl which may be unsubstituted or substituted by -NRS61RS62or -OR561;

[0049] RS42, RS43are independently selected from Ci to Ce alkoxy and Ci to Ce alkyl which both may be unsubstituted or substituted by -NRS61RS62or -OR561;

[0050] RS51, RS52are independently selected from Ci to Ce alkyl which may be unsubstituted or substituted by -NRS61RS62or -OR561;

[0051] RS61, RS62are independently selected from H and Ci to Ce alkyl;

[0052] Xs1is a Ci to Ce alkanediyl; and m is an integer of from 1 to 30. Yet another embodiment of the present invention is the use of a composition as described herein or a mixture of a concentrate as described herein with an oxidizer for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content and optionally a silicon oxide layer, wherein the first germanium content is higher than the second germanium content.

[0053] Yet another embodiment of the present invention is a process of selectively removing a first silicon germanium alloy layer having a first germanium content from a surface of a microelectronic device relative to a silicon layer or a second silicon germanium alloy layer having a second germanium content and and optionally a silicon oxide layer, wherein the first germanium content is higher than the second germanium content, the process comprising:

[0054] (a) providing a microelectronic device surface that includes the layer comprising the silicon germanium alloy and the silicon layer and optionally the silicon oxide layer,

[0055] (b) providing a composition as described herein or by mixing a concentrate as described herein with an oxidizer, and

[0056] (c) contacting the surface with the composition for a time and at a temperature effective to selectively remove the layer comprising silicon-germanium relative to the layer comprising or consisting of Si and optionally the silicon oxide layer.

[0057] Yet another embodiment of the present invention is a process for the manufacture of a semiconductor device, comprising the process of selectively removing the first silicon germanium alloy layer having the first germanium content from the surface relative to the silicon layer or the second silicon germanium alloy layer having a second germanium content and optionally a silicon oxide layer as described herein.

[0058] Detailed Description of the Invention

[0059] The etching composition according to the present invention is useful for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content, wherein the first germanium content is higher than the second ge rmanium content. The composition is particularly useful for etching SiGe against Si if an additional layer comprising or consisting of silicon oxide (SIOX), silicon oxynitride (SION) and / or silicon nitride (SIN) are present.

[0060] The composition comprises:

[0061] (a) 0.1 to 10 % by weight of an oxidizing agent, wherein the oxidizing agent is selected from a peroxide;

[0062] (b) 1 to 14 % by weight of an etchant comprising a source of fluoride ions;

[0063] (c) 0.0005 to 4 % by weight of an Si protecting agent of formula P1 or of formula P2 or of formula P3

[0064] (d) optionally 0.001 to 3 % by weight of an SiOxprotecting agent of formula S41 or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by cocondensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more and

[0065] (e) water; as further described below.

[0066] Definitions

[0067] As used herein, a “silicon layer” or “Si layer” include, but is not limited to, a layer essentially consisting of elemental silicon, particularly amorphous or crystalline silicon (Si); p-doped silicon; and n-doped silicon. The “silicon layer” excludes silicon germanium alloys (SiGe), silicon oxides (SiOx) or SiN / SiON layers. 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.

[0068] As used herein, “silicon oxide layers” or “SIOXlayers” correspond to layers that were deposited from a silicon oxide precursor source, e.g., TEOS, thermally deposited silicon oxide, or carbon doped oxides (CDO) deposited using commercially available precursors such as SILK™, AURORA™, CORAL™ or BLACK DIAMOND™. “Silicon oxide” is meant to broadly include SIOX, CDO's, siloxanes and thermal oxides. Silicon oxide or SIOXmaterial corresponds to pure silicon oxide (SIO2) as well as impure silicon oxide including impurities in the structure.

[0069] As used herein, SIN refers to silicon nitride and silicon oxynitride.

[0070] As used herein, the “silicon-germanium layers” or“SIGe layers” correspond to layers essentially consisting of silicongermanium (SIGe) alloys known in the art. The term “essentially consisting of silicon” means that the SIGe content in the layer is more than 90% by weight, preferably more than 95% by weight, even more preferably more than 98% by weight, and most preferably consists of SIGe. Silicon germanium or SIGe is generally represented by the formula SixGey, wherein x is in a range from about 0.50 to about 0.90, particularly about 0.60 to about 0.85 or about 0.70 to about 0.90, and y is in a range from about 0.10 to about 0.50, particularly from about 0.15 to about 0.40 or about 0.10 to about 0.30, with x+y= 1 .00. SIGe25 here means that y is 0.25 while SIGe40 means that y is 0.40, which are particularly preferred.

[0071] As used herein, “SiGehigh means a SIGe with a higher Ge content, “SiGei0W” means a SIGe with a lower Ge content. Preferably, the Ge content of SiGehigh is at least 5% higher than the Ge content of the SIGeiow, more preferably the Ge content of SiGehigh is at least 10% higher than the Ge content of the SIGeiow. Without limitation, the following SIGe layers may advantageously be etched against each other: SIGe40 vs SIG25, SIGe40 vs. SIGe20.

[0072] As used herein, the term “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 a SIGe or SiGehigh layer in the presence of a layer comprising or consisting of a second material, in this case a Si layer or a SIGeiow layer, the etch rate of said composition for etching the first layer is significantly higher compared to the etch rate of said composition for the second layer. Depending on the substrate to be etched, other layers like SIOX, SION or SIN or hard mask materials should also not be jeopardized.

[0073] SIGe40 / SI selectivity may be up to more than 200, preferably more than 250, most preferably more than 400. The SIGe40 / SIGe25 selectivity may be up to more than 3, preferably more than 5, most preferably more than 10.

[0074] As used herein, the term “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. As used herein, the term “alkylaryl” means an aryl that is substituted by an alkyl, such as but not limited to 2, 3, or 4- toluyl. The term “arylalkyl” means an alkyl that is substituted by aryl, such as but not limited to benzyl.

[0075] The term “particularly” or “preferably” shall indicate non-limiting advantageous examples of a generic term and shall have the meaning of “such as but not limited to”. By providing preferred embodiments that are covered by a generic term it is not intended to limit the generic term in any way.

[0076] As used herein, “chemical bond” means that the respective moiety is not present but that the adjacent moieties are bridged so as to form a direct chemical bond between these adjacent moieties. By way of example, if in a molecule A-B-C the moiety B is a chemical bond then the adjacent moieties A and C together form a group A-C.

[0077] 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, “alkyl” refers to linear, branched or cyclic alkyl or a combination thereof. As used herein, “alkanediyl” refers to a diradical of linear, branched or cyclic alkanes or a combination thereof.

[0078] All percent, ppm or comparable values refer to the weight with respect to the total weight of the respective composition except where otherwise indicated. The term “wt%” means % by weight. The term ppm means part per million by mass.

[0079] All cited documents are incorporated herein by reference.

[0080] Oxidizing agent

[0081] The etching composition according to the invention comprises an oxidizing agent. The oxidizing agent, also referred to as “oxidizer”, is one or more compounds that are capable of oxidizing Silicon Germanium alloys.

[0082] Preferably the oxidizing agent is different from the other components of the composition, particularly different from the etching agent. Therefore, the oxidizing agent is preferably free of any source of fluoride ions.

[0083] The oxidizing agent comprises or consists of a peroxide. Useful peroxides may be but are not limited to hydrogen peroxide or peroxymonosulfuric acid or organic acid peroxides like peroxyacetic acid, and their salts.

[0084] The most preferred oxidizing agent is hydrogen peroxide.

[0085] The oxidizing agent may be used in an amount of from about 0.1 to about 10 % by weight, preferably from about 0.5 to 8 % by weight, more preferably from about 1 to 6 % by weight, even more preferably from about 1.5 to about 5% by weight, most preferably of from about 2 to about 4 % by weight. Etchant

[0086] The etching composition according to the invention comprises a source of fluoride ions which may be any compound that is capable of releasing fluoride ions.

[0087] Preferably the etchant is different from the other component in the composition, particularly is different from the oxidizing agent. Therefore, the etchant preferably has no oxidizing capabilities with respect to any of the materials on the surface of the substrate to be treated, particularly Si or SiGe.

[0088] Preferred etchants are selected from but not limited to the group consisting of ammonium fluoride, ammonium bifluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine trihy-drofluoride, hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetra-fluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid, fluorosilicic acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate, and mixtures thereof. Preferably the etchant consists of one or more, most preferably one of the said compounds.

[0089] Most preferably the etchant comprises or consists of ammonium fluoride, ammonium hydrogen fluoride, and hydrogen fluoride. Most preferably the etchant comprises or consists of ammonium fluoride.

[0090] The etching compositions according to the invention comprising ammonium fluoride as the etchant have shown a stable and reproducible controlled selective etch rate for etching a SiGe layer, particularly SIGe25, or a SIGehigh layer, particularly SIGe40, in the presence of a Si layer or a SIGei0Wlayer, particularly SiGe 10, SiGe 15, SIGe20, or SIGe25.

[0091] The etchant may be used in an amount of from about 1 to about 14 % by weight, preferably of from about 2 to about 13 % by weight, more preferably of from about 3 to about 12 % by weight, even more preferably of from about 4 to about 1 1 % by weight, most preferably of from about 6 to about 10 % by weight.

[0092] Compositions according to the invention comprising the etchant in the here defined preferred total amounts have shown a superior etch rate, in particular for etching a layer comprising or consisting of SiGe, preferably of SiGe25, and etch rate selectivity, in the presence of a layer comprising or consisting of Si.

[0093] Si protecting agent

[0094] The composition comprises a (first) Si protecting agent that are epoxy ether compounds of formula P1 or dihydroxyether compounds of formula P2 or alpha hydroxy carboxylic acids of formula P3

[0095] The Si protecting agent may be used to etch a SIGe layer against a Si layer. Alternatively, a SIGehigh layer may be etched against a SIGei0Wlayer. In both cases the etch rate of a SIGe layer, preferably of SIGe25, are still high, which leads to SIGe / SI, particularly SIGe25 / SI selectivity.

[0096] Epoxy compounds

[0097] In the epoxy compounds of formula P1 , the group RP1may be selected from (a) Ci to C10 alkyl, preferably methyl, ethyl, prop-1-yl or prop-2-yl, butyl, pentyl, hexyl, heptyl, 2 -ethyl-hex-1 -yl, or (b) C3 to C10 alkenyl, preferably prop-1 - en-3-yl.

[0098] Alternatively, RP1may be selected from the groups wherein XP2may be a divalent group selected from a Ci to Ge alkyl, preferably ethanediyl, propanediyl, butanediyl, pentanediyl, and hexanediyl, more preferably ethane-1 ,2-diyl, propane-1 , 3-diyl, butane-1 ,4-diyl, and hexane-1 ,6-diyl, most preferably butane-1 , 4-diyl.

[0099] In formula P1 , preferred groups RP1are a Ci to C4 alkyl or the group wherein, XP2may be a divalent group selected from ethanediyl, propanediyl, butanediyl, and hexanediyl, more preferably ethane-1 ,2-diyl, propane-1 , 3-diyl, butane-1 ,4-diyl, and hexane-1 ,6-diyl, most preferably butane-1 ,4-diyl. Longer more hydrophobic alkyl groups may generally be used but may have some solubility limitations.

[0100] XP1may be a divalent group selected from Ci to Ce alkanediyl, preferably Ci to C4 alkanediyl particularly methanediyl and ethanediyl.

[0101] RP2may be selected from H or a Ci to Ce alkyl, preferably H or a Ci to C4 alkyl, more preferably H, methyl or ethyl, most preferably H.

[0102] Particularly preferred epoxy compounds of formula P1 are (2R)-2-(Methoxymethyl)oxirane, 2- (Isopropoxymethyl)oxirane, 2-(Butoxymethyl)oxirane, and 2-[4-(Oxiran-2-ylmethoxy)-butoxymethyl]oxirane.

[0103] Dihydroxy compounds

[0104] In the dihydroxy compounds of formula P2 the group RP1may be selected from (a) Ci to C10 alkyl, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-methyl-hexyl, 2-ethyl-hexyl, most preferably methyl, ethyl, prop-1 -yl or prop-2-yl, or 2-ethyl-hex-1-yl, or but-1 -yl; or (b) C3 to C10 alkenyl, particularly, prop-1 -en-3-yl.

[0105] Alternatively, RP1may be selected from the groups wherein XP2may be a divalent group selected from a Ci to C alkyl, preferably ethanediyl, propanediyl, butanediyl, pentanediyl, and hexanediyl, more preferably ethane-1 , 2-diyl, propane-1 , 3-diyl, butane-1 , 4-diyl, and hexane-1 , 6-diyl, most preferably butane-1 , 4-diyl. Longer more hydrophobic alkyl groups may generally be used but may have some solubility limitations.

[0106] In formula P2 preferred groups RP1are a Ci to C4 alkyl or the group wherein, XP2may be a divalent group selected from ethanediyl, propanediyl, butanediyl, and hexanediyl, more preferably ethane-1 ,2-diyl, propane-1 , 3-diyl, butane-1 ,4-diyl, and hexane-1 ,6-diyl, most preferably butane-1 ,4-diyl.

[0107] XP1may be a divalent group selected from Ci to Ce alkanediyl, preferably Ci to C4 alkanediyl particularly methanediyl and ethanediyl.

[0108] RP2may be selected from H or a Ci to Ce alkyl, preferably H or a Ci to C4 alkyl, more preferably H, methyl or ethyl, most preferably H.

[0109] Particularly preferred dihydroxy compounds of formula P2 are 3-butyloxy-1 ,2-propanediol, 3-isopropoxy-1 ,2- propanediol, 3-(allyloxy)-1 ,2-propanediol, and 3-[(2-ethylhexyl)oxy]-1 ,2-propanediol.

[0110] Hydroxycarboxylic acids

[0111] In a first embodiment of the compounds of formula P3 the group RP3may be selected from a Ci to C10 alkyl, particularly methyl, ethyl, propyl, butyl, pentyl, or hexyl. Longer more hydrophobic alkyl groups may generally be used but may have some solubility limitations.

[0112] In a second embodiment of formula P3 the group RP3may be a Ce to C12 aryl or alkylaryl, particularly phenyl, toluyl, ethylphenyl, dimethylphenyl, diethylphenyl, or napthyl. Particularly preferred are phenyl, toluyl, ethylphenyl.

[0113] In a third embodiment of formula P3 the group RP3may be a Ce to C12 arylalkyl, particularly benzyl, phenylethyl, phenylpropyl, and naphthylmethyl.

[0114] Group RP4may be (independently) selected from one of the groups RP3as defined above or H, particularly H or methyl. In a preferred embodiment, if RP3is methyl, then RP4is selected from one of the groups RP3, preferably a Ci to Ce alkyl.

[0115] Particularly preferred dihydroxy compounds of formula P3 are 2-hydroxy-2-methylpropanoic acid, 2-hydroxy-2- phenylpropanoic acid, 2-hydroxy-2-phenylacetic acid.

[0116] The concentration of the the Si protecting agents of formulae P1 , P2 or P3 may generally be in the range of from about 0.0005 to about 4 % by weight. The Si protecting agents of formulae P1 or P2 are preferably used in an amount of from about 0.001 to about 1.5 % by weight, even more preferably from about 0.003 to about 1 % by weight, most preferably from about 0.005 to about 0.6 % by weight. The Si protecting agent of formula P3 is preferably used in an amount of from about 0.1 to about 4 % by weight, even more preferably from about 0.3 to about 3.7 % by weight, most preferably from about 0.5 to about 3.5 % by weight. There may be one or more Si protecting agents in the composition, however it is preferred to use only one additive of formula P1 , P2 or P3.

[0117] Second Si protecting agent

[0118] The composition may further comprise a second Si protecting agent of formula S1 as described in WO 2022 / 043165

[0119] RS1- =— RS2(SD that further reduces the etching of the Si layer or SiGei0Wlayer, whereas the etch rate of the SiGe or SiGehigh layer, preferably of SiGe25 or SiGe40, are still high, which may lead to further increased SiGe / Si particularly SiGe25 / Si selectivities.

[0120] In formula S1 RS1may be selected from XS-OH and YS-(CO)-OH, wherein Xsmay be a linear or branched Ci to C10 alkanediyl, a linear or branched C2 to C10 alkenediyl, linear or branched C2 to C10 alkynediyl, or a polyoxyalkylene group -Xs1-(O-C2H3R6)m-; YS1may be the same as Xsor may be a chemical bond. If RS1is a polyoxyalkylene group, Xs1may be a Ci to Ca alkanediyl, preferably a Ci to Ce alkanediyl, most preferably ethanediyl, propanediyl or butanediyl; furthermore, m is integer selected from 1 to 30, preferably from 1 to 20, most preferably from 1 to 15. The higher m is, the lower is the effect of the second Si protecting agent for Si over SiGe. If m is too high, the second Si protecting agent does not sufficiently reduce the a-Si, SIOX, SION or SIN etch rates. For etching SiGe against SiGe, a higher m value such as from 5 to 20 or even 20 to 40 is preferred.

[0121] RS2may be selected from RS1, preferably RS2is the same as RS1describe above.

[0122] Alternatively RS2may be (II) H, (ill) a Ci to C10 alkyl, (iv) a Ci to C10 alkenyl, (v) a Ci to C10 alkynyl, and (vi) -XS1-(O- C2H3RS6)m-ORS6, wherein Xs1is a Ci to Ce alkanediyl, preferably ethanediyl, propanediyl or butanediyl; RS6is selected from H and Ci to Ce alkyl, preferably H, methyl or ethyl; and m may be an integer of from 1 to 30.

[0123] Most preferably RS1and RS2are the same.

[0124] In a first preferred embodiment RS1may be XS-OH. Preferably Xsmay be a Ci to Ca alkanediyl, more preferably a Ci to Ce alkane-1 ,1 -diyl.

[0125] Preferably Xsis selected from a C3 to C10 alkanediyl, more preferably from C4 to Ca alkanediyl.

[0126] Particularly preferably Xsis selected from methanediyl, ethane-1 ,1 -diyl, and ethane-1 , 2-diyl. In another preferred embodiment X5is selected from propan-1 ,1 -diyl, butane-1 ,1-diyl, pentane-1 ,1 -diyl, and hexane- 1,1 -diyl. In yet another preferred embodiment Xsis elected from propane-2-2-diyl, butane-2, 2-diyl, pentane-2, 2-diyl, and hexane- 2, 2-diyl. In yet another preferred embodiment Xsis elected from propane-1 -2-diyl, butane-1 , 2-diyl, pentane-1 , 2-diyl, and hexane-1 ,2-diyl. In yet another preferred embodiment Xsis elected from propane-1 -3-diyl, butane-1 ,3-diyl, pentane-1 ,3-diyl, and hexane-1 , 3-diyl. Particular preferred groups Xsare butane-1 , 1 -diyl, pentane-1 ,1 -diyl, and hexane-1 , 1 -diyl, heptane-1 ,1 -diyl and octane-1 , 1 -diyl.

[0127] Preferably the second Si protecting agent is is a compound of formula S2 wherein

[0128] RSH,Rs2iareindenpendetly selected from a Ci to C10 alkyl, preferably from ethyl, propyl, butyl, pentyl and hexyl, most preferably from propyl, butyl, or pentyl.

[0129] RS12, RS22are independetly selected from H and a Ci to C4 alkyl, preferably H, methyl or ethyl.

[0130] For etching SiGe against Si, most preferably the (first) second Si protecting agent may be a compound of formula S4 (2,4,7,9-Tetramethyl-5-decyne-4,7-diol (TMDD))

[0131] For etching SiGe having a higher Ge content against SiGe having a lower Ge content, most preferably the (first) second Si protecting agent may be a compound of formula S5 wherein

[0132] RS11, RS21are indenpendetly selected from a Ci to C10 alkyl, preferably from ethyl, propyl, butyl, pentyl and hexyl, most preferably from propyl, butyl, or pentyl.

[0133] RS12, RS22are independetly selected from H and a Ci to C4 alkyl, preferably H, methyl or ethyl k, I are integers independently selected from 1 to 30, prefarbly from 1 to 20, most preferably from 1 to 15. Advantageously the sum of k and I is about 5 to 20 or about 20 to 40.

[0134] The second Si protecting agent of the first preferred embodiment may be present in an amount of from about 0.0005 to about 0.03 % by weight, preferably of from about 0.001 to about 0.02 % by weight, most preferably of from about 0.005 to about 0.015 % by weight. In a second preferred embodiment, RS1may be YS-(CO)-OH, wherein YS1may be a chemical bond or the same as Xsdescribed above.

[0135] Preferably the second Si protecting agent may be a compound of formula S3

[0136] The second Si protecting agent of the second preferred embodiment may be present in an amount of from about 0.1 to about 3 % by weight, preferably of from about 0.5 to about 2 % by weight.

[0137] The composition according to the invention may comprise one or more of the second Si protecting agents described herein.

[0138] A particularly preferred composition comprises one single second Si protecting agent of the first preferred embodiment, particularly one single second Si protecting agent of formula S2 or formula S4.

[0139] SiOxprotecting agent

[0140] The composition may further comprise a silane as SiOxprotecting agent as described in WO 2023 / 161058. The SiOxprotecting agent further increases the SiGe / SiOx, SiGe / SiON or SiGe / Si N selectivity. It also has the function of a hardmask protecting agent that significantly improves the hardmask compatibility of the SiGe etching composition. The SiOxprotecting agent may be particularly advantageously used in combination with the Si protecting agent.

[0141] In a first embodiment monomeric silanes of formula S41 may be used as SiOxprotecting agent: wherein

[0142] RS41is Ci to Ce alkyl which may be unsubstituted or substituted by by -NRS61RS62or -OR561;

[0143] RS42is independently selected from Ci to Ce alkoxy and Ci to Ce alkyl which may be unsubstituted or substituted by -NRS61RS62or -OR561;

[0144] RS51, RS52are independently selected from Ci to Ce alkyl which may be unsubstituted or substituted by - NRS61RS62or -OR561.

[0145] In a preferred embodiment RS41is Ci to C5 alkyl, preferably Ci to C4 alkyl, even more preferably methyl, ethyl or propyl, most preferably methyl or ethyl. In a first preferred alternative RS42is Ci to C5 alkyl, preferably Ci to C4 alkyl, even more preferably methyl, ethyl or propyl, most preferably methyl or ethyl. In a second preferred alternative RS42is Ci to C5 alkoxy, preferably Ci to C4 alkoxy, even more preferably methoxy, ethoxy, or propoxy, most preferably methoxy or ethoxy.

[0146] In a preferred embodiment RS51and RS52are independently Ci to C5 alkyl, preferably Ci to C4 alkyl, even more preferably methyl, ethyl or propyl, most preferably methyl or ethyl.

[0147] All substituents RS41, RS42, RS51, and RS52may be unsubstituted or substituted by one or more -NRS61RS62or OR561, preferably unsubstituted or substituted by one or more -NH2, -NHR571, and -NHRS71RS72, wherein RS71and RS71are independently methyl, ethyl, propyl or butyl. Most preferably all substituents RS41, RS42, RS51, and RS52are unsubstituted.

[0148] In a preferred embodiment silanes of formula S49 may be used: wherein

[0149] RS51, RS52, RS53are independently selected from methyl, ethyl, propyl and butyl , preferably methyl and ethyl; RS41is selected from methyl, ethyl, propyl and butyl, preferably methyl and ethyl.

[0150] All substituents RS41, RS51, RS52, and RS53may be unsubstituted or substituted by one or more -NRS61RS62or OR561, preferably unsubstituted or substituted by one or more -NH2, -NHR571, and -NHRS71RS72, wherein RS71and RS71are independently methyl, ethyl, propyl or butyl. Most preferably all substituents RS41, RS51, RS52, and RS53are unsubstituted

[0151] Particularly preferred are methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane and ethyltriethoxysilane.

[0152] In a second embodiment the SIOXprotecting agent are derivatives of the monomeric silanes described above that are obtainable by homocondensation of the compounds of formula S41 or by co-condensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more, preferably 0.2 or more, even more preferably 0.3 or more, most preferably 0.5 or more

[0153] Such silane condensation products may also form when using the monomeric silanes of formula 41 described above. Usually, due to the low concentrations used in the composition, low average degrees of polymerization of up to about 10, preferably up to about 5, most preferably up to about 3 are to be expected. To some extend the monomeric silanes may also hydrolyze to some extent when using the aqueous etching compositions.

[0154] One type of homocondensates are the linear silanes of formula S43: wherein e is an integer from 0 to 5, preferably 0, 1 or 2, most preferably 1 ; or co-condensates of formula S44 wherein e is an integer from 0 to 5, preferably 0, 1 or 2, most preferably 1 , and wherein at least one, preferably two of RS43are -O-R551.

[0155] Substituent RS43may be unsubstituted or substituted by one or more -NRS61RS62or OR561, preferably unsubstituted or substituted by one or more -NH2, -NHR561, and most preferably unsubstituted.

[0156] Another type of homocondensates are the branched silanes of formula S45: wherein u, v, w are integers independently selected from 0 to 5, preferably 0, 1 , 2 or 3, most preferably 0 or 1 , y is an integer from 1 to 5, preferably 1 or 2, most preferably 1 ; or co-condensates of formula S46 wherein u, v, w are integers independently selected from 0 to 5, preferably 0, 1 , 2 or 3, most preferably 0 or 1 , y is an integer from 1 to 5, preferably 1 or 2, most preferably 1 ; and at least one, preferably two of RS43are -O-R551.

[0157] Yet another type of homocondensates are cyclic silanes of formula S47: wherein n is 0, 1 or 2, preferably 0 or 1 , most preferably 1 ; or co-condensates of formula S48

[0158] The concentration of the silanes of formulae S41 to S48 may generally be in the range of from about 0.001 to about

[0159] 3 % by weight, preferably of from about 0.005 to about 2 % by weight, even more preferably from about 0.05 to about

[0160] 1 % by weight, most preferably from about 0.1 to about 0.5 % by weight.

[0161] There may be one or more silanes in the composition, however it is preferred to use only one additive of formulae S41 to S48.

[0162] Acid or base

[0163] The etching composition according to the invention may further comprise an acid which is different from the Si protecting agent of formula P3. Such acid may be an inorganic acid, an organic acid, or a combination thereof. Preferably the acid is an organic acid or a combination of an inorganic acid and an organic acid.

[0164] Typical inorganic acids may be selected from but are not limited to sulfuric acid or phosphoric acid. Preferably, the inorganic acid comprises or consists of a strong inorganic acid, particularly sulfuric acid.

[0165] Typical organic acids may be selected from but are not limited to Ci to C10 mono, di or tri carboxylic acids, sulfonic acids, phosphonic acids, and the like. Preferred are Ci to C10 mono, di or tri carboxylic acids.

[0166] In a preferred embodiment the acid comprises or consists of an unsubstituted Ci to C3 carboxylic acid, particularly but not limited to acetic acid. In another preferred embodiment the acid comprises or consists of a hydroxy carboxylic acid, particularly but not limited to citric acid or tartaric acid. In yet another preferred embodiment the Si protecting agent (hydroxycarboxylic acid) or the second Si protecting agent (acetylenic compound), has acidic properties and therefore no further acid is required.

[0167] Particularly preferred are acetic acid, phosphoric acid, tartaric acid or citric acid.

[0168] The etching composition according to the invention may further comprise a base. Such bases may be inorganic or organic bases. Inorganic bases are preferred. Bases that do not comprise any metal counter-ions that may interfere with the etching or overall semiconductor manufacturing process, preferably ammonia water or a tetraalkylammonium hydroxide. The most preferred base is ammonia water, NH4OH.

[0169] The acid or base is used to adjust the pH to the prescribed value. A suitable combination of an acid and a base may also be used to work as a buffer to keep the pH at the prescribed value.

[0170] If present, the acid or base may be used in the etching composition in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0. 1 to about 2 % by weight. The acids may be partly or fully subsituted by the Si protecting agents of formula P3.

[0171] Organic solvents

[0172] Even if not preferred, the etching composition may optionally comprise one or more organic solvents.

[0173] 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 tetrahydrofuran (THF), N-methylpyrrolidone (NMP), di-methyl 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.

[0174] 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. Preferably the or at least one water-miscible organic solvent (H) is sulfolane. Particularly, preferred are compositions according to the present invention which do not comprise one or more water-miscible organic solvents.

[0175] In individual cases, a composition according to the invention as defined herein (or a composition according to the invention as described above or below as being preferred) is preferred wherein the total amount of the one or more water-miscible organic solvents, (i.e. the solvent component) present in an amount of from about 0.1 to about 30 % by weight, preferably of from about 0.5 to about 10 % by weight, more preferably of from about 1 to about 7.5 % by weight, even more preferably of from about 1 to about 6 % by weight, based on the total weight of the composition.

[0176] Most preferably the etching composition is an aqueous solution that is essentially free of organic solvents, particularly those described above. Essentially free herein 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. Surfactants

[0177] The composition may also further comprise one or more surfactants.

[0178] Preferred surfactants are selected from the group consisting of

[0179] (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;

[0180] (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)-ammonio}acetate, phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine; and

[0181] (ill) non-ionic surfactants, preferably selected from the group consisting of glucoside alkyl ethers, glycerol alkyl ethers, cocamide ethanolamines and lauryldimethylaminoxide.

[0182] 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.

[0183] Particular preferred surfactants are those of formula F1 wherein

[0184] XF2is a Ci to C4 alkanediyl;

[0185] RF4is a C12 to C30 alkyl or a C12 to C30 alkenyl; and

[0186] RF5is a Ci to C4 alkyl.

[0187] 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. Most preferably the etching composition is essentially free of any surfactants, particularly those described above. Essentially free herein means that the content of surfactants 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.

[0188] Chelating agents

[0189] The etching composition may optionally comprise one or more chelating agents.

[0190] Preferred chelating agents are 1 ,2-cyclohexylenedinitrilotetraacetic acid, 1 ,1 , 1 ,5,5,5-hexafluoro-2,4-pentane-dione, acetylacetonate, 2,2’-azanediyldiacetic acid, ethylenediaminetetra-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, sulfosali-cylic acid, salicylic acid, pyridine, 2-ethylpyridine, 2-methoxypyridine, 3- methoxypyridine, 2-picoline, dimethylpyridine, piperidine, piperazine, tri-ethylamine, triethanolamine, ethylamine, methylamine, isobutylamine, tert-butylamine, tributylamine, dipropylamine, dimethylamine, diglycol amine, monoethanolamine, methyldiethanolamine, pyrrole, isoxazole, bipyridine, py-rimidine, pyrazine, pyridazine, quinoline, isoquinoline, indole, 1 -methylimidazole, diisopropylamine, diisobutylamine, aniline, pentamethyldi-ethylenetriamine, acetoacetamide, ammonium carbamate, ammonium pyr-rolidinedithiocarbamate, 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;

[0191] In a preferred embodiment the chelating agent may be Diethylenetriaminepentaacetic acid (DTPA) or may comprise DTPA as well as one or more of the other chelating agents above. Compositions comprising DTPA as chelating agent have shown particularly low etch rates for silicon oxide.

[0192] A composition according to the invention as defined herein is also preferred wherein the amount of the one or more chelating agents present is of from about 0.005 to about 2 % by weight, preferably of from about 0.01 to about 1 % by weight, more preferably of from about 0.02 to about 0.2 % by weight, based on the total weight of the composition.

[0193] Most preferably the etching composition is essentially free of any chelating agents, particularly those described above. Essentially free herein means that the content of chelating agents 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.

[0194] Composition

[0195] In a preferred embodiment the pH of the etching composition is from 4 to 8, particularly from 5 to 7. If the pH is too low, the silicon oxide etch rate is too high, if the pH is too high, the Si etch rate is too high. The pH of the bath may be adjusted by a pH adjustor, particularly ammonia. A composition according to the invention as defined herein is specifically preferred wherein the composition essentially consists or consists of the oxidizer, particularly hydrogen peroxide, the etchant, particularly ammonium fluoride, a Si protecting agent of formula P1 , P2, or P3, optionally a second Si protecting agent of formula S1 , optionally an SIOXprotecting agent of formula S41, optionally a surfactant, optionally an acid, optionally a base, and water, as defined herein and to be defined based on the examples.

[0196] A composition according to the invention as defined herein is specifically preferred wherein the composition essentially consists or consists of hydrogen peroxide, ammonium fluoride, the Si protecting agent of formula P1 , P2, or P3, optionally a second Si protecting agent of formula S1 , an SIOXprotecting agent of formula S41 , optionally a surfactant of formula S4, optionally an acid, optionally a base, and water, as defined herein and to be defined based on the examples.

[0197] A composition is particularly preferred wherein the composition comprises or essentially consists of or consists of

[0198] (a) one or more oxidizing agents selected from a peroxide, and preferably the one or more oxidizing agent consist of or comprise hydrogen peroxide, in an amount of from about 1 to about 2 % by weight, more preferably from about 2 to about 12 % by weight, even more preferably from about 3 to about 7 % by weight, most preferably of from about 4 to about 6 % by weight;

[0199] (b) one or more etchants comprising a source of fluoride ions, selected from the group consisting of ammonium fluoride, ammonium bifluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine trihydrofluoride, hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoro acetic acid, fluorosilicic acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures thereof, and preferably consists of or comprises ammonium fluoride, hydrogen fluoride or a combination thereof, in an amount of from about 1 to about 14 % by weight, preferably of from about 2 to about 13 % by weight, more preferably of from about 3 to about 12 % by weight, even more preferably of from about 4 to about 11 % by weight, most preferably of from about 6 to about 10 % by weight;

[0200] (c) an Si protecting agent of formula P1 , P2, P3, or combinations thereof, wherein the Si protecting agent of formula P1 , P2 are present in an amount of from about 0.0005 to about 4 %, preferably from about 0.001 to about

[0201] 1 .5 % by weight, even more preferably from about 0.003 to about 1 % by weight, most preferably from about 0.005 to about 0.6 % by weight, and the Si protecting agent of formula P3 is present in an amount of from about 0.0005 to about 4 % by weight, preferably from about 0.1 to about 4 % by weight, even more preferably from about 0.3 to about 3.7 % by weight, most preferably from about 0.5 to about 3.5 % by weight;

[0202] (d) optionally an SIOXprotecting agent of formula S41 in an amount of from about 0.001 to about 3 % by weight, preferably of from about 0.005 to about 2 % by weight, even more preferably from about 0.05 to about 1 % by weight, most preferably from about 0.1 to about 0.5 % by weight, or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by co-condensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more;

[0203] (e) optionally one or more acids selected from an inorganic acid and an organic acid different from the Si protecting agents of formula P3, preferably an organic acid or phosphoric acid, more preferably a Ci to C10 mono, di or tri carboxylic acid, even more preferably an unsubstituted organic acid or a hydroxycarboxylic acid different from the Si protecting agents of formula P3, most preferably acetic acid, citric acid, tartaric acid, or a combination thereof, and preferably consists of or comprises acetic, citric acid, or tartaric acid in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight; The acids may be at least partly exchanged by Si protecting agents of formula P3;

[0204] (f) optionally one or more bases, preferably NH4OH or tetramethylammonium hydroxide, most preferably NH4OH, in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight;

[0205] (g) optionally one or more surfactants selected from the group consisting of (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), perfluorooctanesulfonate, perfluorobutanesulfonate, perfluoro nonanoate and perfluorooctanoate; alkyl-aryl ether phosphates and alkyl ether phosphates, (II) zwitterionic surfac-tants, preferably selected from the group consisting of (3-[(3-cholamidopropyl)dimethylammonio]-1 -propanesulfonate), cocamidopropyl hydroxysultaine, {[3-(dodecanoylamino)propyl](dimethyl)ammonio}acetate, phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine, (ill) non-ionic surfactants, preferably selected from the group consisting of glucoside alkyl ethers, glycerol alkyl ethers, cocamide ethanolamines and lauryldime-thylaminoxide; and preferably the one or more surfactants are or comprise a compound of formula F1 , if present, in an amount 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;

[0206] (h) optionally one or more chelating agents selected from the group consisting of diethylenetriaminepentaacetic acid, 1,2-cyclohexylenedinitrilotetraacetic acid, 1 ,1 , 1 ,5,5,5-hexafluoro-2,4-pentane-dione, acetylacetonate, 2,2’- azanediyldiacetic acid, ethylenediaminetetra-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, pyridine, 2-ethylpyridine, 2-methoxypyridine, 3-methoxypyridine, 2-picol ine, dimethylpyridine, piperidine, piperazine, tri-ethylamine, triethanolamine, ethylamine, methylamine, isobutylamine, tert-butylamine, tributylamine, dipropylamine, dimethylamine, diglycol amine, monoethanolamine, 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 there-of, and preferably is or comprises 1 , 2-cyclo hexylenedi nitrilotetraacetic acid, in an amount of from about 0.005 to about 2 wt%, preferably in a total amount of from about 0.01 to about 1 wt%, more preferably in a total amount of from about 0.02 to about 0.2 wt%, based on the total weight of the composition; (k) optionally one or more water-miscible organic solvents, preferably selected from the group consisting of tetrahydrofuran (THF), N-methylpyrrolidone (NMP), di-methyl formamide (DMF), dimethyl sulfoxide (DMSO) and sulfolane (2,3,4,5-tetrahydrothiophene-1 ,1 -dioxide) and mixtures thereof, in an amount of from about 0.1 to about 30 wt%, preferably of from about 0.5 to about 10 wt%, more preferably of from about 1 to about 7.5 wt%, even more preferably of from about 1 to about 6 wt%; and

[0207] (l) water as balance to a total of 100 wt.% of the composition in each case; all based on the total weight of the composition, wherein the pH of the composition is preferably of from about 4 to about 8, more preferably of from about 5 to about 7, and wherein the % amounts of the components add to 100 % by weight in each case.

[0208] Another composition is particularly preferred wherein the composition comprises or essentially consists of or consists of

[0209] (a) one or more oxidizing agents selected from a peroxide, and preferably the one or more oxidizing agent consist of or comprise hydrogen peroxide, in an amount of from about 1 to about 2 % by weight, more preferably from about 2 to about 12 % by weight, even more preferably from about 3 to about 7 % by weight, most preferably of from about 4 to about 6 % by weight;

[0210] (b) one or more etchants comprising a source of fluoride ions, selected from the group consisting of ammonium fluoride, ammonium bifluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine trihydrofluoride, hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoro acetic acid, fluorosilicic acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures thereof, and preferably consists of or comprises ammonium fluoride, hydrogen fluoride or a combination thereof, in an amount of from about 1 to about 14 % by weight, preferably of from about 2 to about 13 % by weight, more preferably of from about 3 to about 12 % by weight, even more preferably of from about 4 to about 11 % by weight, most preferably of from about 6 to about 10 % by weight;

[0211] (c) an Si protecting agent of formula P1 , P2, P3, or combinations thereof, wherein the Si protecting agent of formula P1 , P2 are present in an amount of from about 0.0005 to about 4 %, preferably from about 0.001 to about

[0212] 1 .5 % by weight, even more preferably from about 0.003 to about 1 % by weight, most preferably from about 0.005 to about 0.6 % by weight, and the Si protecting agent of formula P3 is present in an amount of from about 0.0005 to about 4 % by weight, preferably from about 0.1 to about 4 % by weight, even more preferably from about 0.3 to about 3.7 % by weight, most preferably from about 0.5 to about 3.5 % by weight;

[0213] (d) optionally an SiOxprotecting agent of formula S41 in an amount of from about 0.001 to about 3 % by weight, preferably of from about 0.005 to about 2 % by weight, even more preferably from about 0.05 to about 1 % by weight, most preferably from about 0.1 to about 0.5 % by weight, or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by co-condensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more;

[0214] (e) optionally one or more acids selected from an inorganic acid and an organic acid different from the Si protecting agents of formula P3, preferably an organic acid or phosphoric acid, more preferably a Ci to C10 mono, di or tri carboxylic acid, even more preferably an unsubstituted organic acid or a hydroxycarboxylic acid different from the Si protecting agents of formula P3, most preferably acetic acid, citric acid, tartaric acid, or a combination thereof, and preferably consists of or comprises acetic, citric acid, or tartaric acid in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight; The acids may be at least partly exchanged by Si protecting agents of formula P3;

[0215] (f) optionally one or more bases, preferably NH4OH or tetramethylammonium hydroxide, most preferably NH4OH, in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight;

[0216] (I) water as balance to a total of 100 wt.% of the composition in each case; all based on the total weight of the composition, wherein the pH of the composition is preferably of from about 4 to about 8, more preferably of from about 5 to about 7, and wherein the % amounts of the components add to 100 % by weight in each case.

[0217] Another composition is particularly preferred wherein the composition comprises or essentially consists of or consists of

[0218] (a) one or more oxidizing agents selected from a peroxide, and preferably the one or more oxidizing agent consist of or comprise hydrogen peroxide, in an amount of from about 1 to about 2 % by weight, more preferably from about 2 to about 12 % by weight, even more preferably from about 3 to about 7 % by weight, most preferably of from about 4 to about 6 % by weight;

[0219] (b) one or more etchants comprising a source of fluoride ions, selected from the group consisting of ammonium fluoride, ammonium bifluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine trihydrofluoride, hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoro acetic acid, fluorosilicic acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures thereof, and preferably consists of or comprises ammonium fluoride, hydrogen fluoride or a combination thereof, in an amount of from about 1 to about 14 % by weight, preferably of from about 2 to about 13 % by weight, more preferably of from about 3 to about 12 % by weight, even more preferably of from about 4 to about 11 % by weight, most preferably of from about 6 to about 10 % by weight;

[0220] (c) an Si protecting agent of formula P1 , P2, P3, or combinations thereof, wherein the Si protecting agent of formula P1 , P2 are present in an amount of from about 0.0005 to about 4 %, preferably from about 0.001 to about

[0221] 1 .5 % by weight, even more preferably from about 0.003 to about 1 % by weight, most preferably from about 0.005 to about 0.6 % by weight, and the Si protecting agent of formula P3 is present in an amount of from about 0.0005 to about 4 % by weight, preferably from about 0.1 to about 4 % by weight, even more preferably from about 0.3 to about 3.7 % by weight, most preferably from about 0.5 to about 3.5 % by weight;

[0222] (d) optionally an SIOXprotecting agent of formula S41 in an amount of from about 0.001 to about 3 % by weight, preferably of from about 0.005 to about 2 % by weight, even more preferably from about 0.05 to about 1 % by weight, most preferably from about 0.1 to about 0.5 % by weight, or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by co-condensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more;

[0223] (e) optionally one or more acids selected from an inorganic acid and an organic acid different from the Si protecting agents of formula P3, preferably an organic acid or phosphoric acid, more preferably a Ci to C10 mono, di or tri carboxylic acid, even more preferably an unsubstituted organic acid or a hydroxycarboxylic acid different from the Si protecting agents of formula P3, most preferably acetic acid, citric acid, tartaric acid, or a combination thereof, and preferably consists of or comprises acetic, citric acid, or tartaric acid in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight; The acids may be at least partly exchanged by Si protecting agents of formula P3;

[0224] (f) optionally one or more bases, preferably NH4OH or tetramethylammonium hydroxide, most preferably NH4OH, in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight;

[0225] (I) water as balance to a total of 100 wt.% of the composition in each case; all based on the total weight of the composition, wherein the pH of the composition is from about 4 to about 8, more preferably of from about 5 to about 7, and wherein the % amounts of the components add to 100 % by weight in each case.

[0226] Another composition is particularly preferred wherein the composition comprises or essentially consists of or consists of

[0227] (a) one or more oxidizing agents selected from a peroxide, and preferably the one or more oxidizing agent consist of or comprise hydrogen peroxide, in an amount of from about 1 to about 2 % by weight, more preferably from about 2 to about 12 % by weight, even more preferably from about 3 to about 7 % by weight, most preferably of from about 4 to about 6 % by weight;

[0228] (b) one or more etchants comprising a source of fluoride ions, selected from the group consisting of ammonium fluoride, ammonium bifluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine trihydrofluoride, hydrogen fluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoro acetic acid, fluorosilicic acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate and mixtures thereof, and preferably consists of or comprises ammonium fluoride, hydrogen fluoride or a combination thereof, in an amount of from about 1 to about 14 % by weight, preferably of from about 2 to about 13 % by weight, more preferably of from about 3 to about 12 % by weight, even more preferably of from about 4 to about 11 % by weight, most preferably of from about 6 to about 10 % by weight;

[0229] (c) either (d ) an Si protecting agent of formula P1 or P2 in an amount of from about 0.0005 to about 4 %, preferably from about 0.001 to about 1.5 % by weight, even more preferably from about 0.003 to about 1 % by weight, most preferably from about 0.005 to about 0.6 % by weight, or (c2) an Si protecting agent of formula P3 in an amount of from about 0.0005 to about 4 % by weight, preferably from about 0.1 to about 4 % by weight, even more preferably from about 0.3 to about 3.7 % by weight, most preferably from about 0.5 to about 3.5 % by weight;

[0230] (e) optionally one or more acids selected from an inorganic acid and an organic acid different from the Si protecting agents of formula P3, preferably an organic acid or phosphoric acid, more preferably a Ci to C10 mono, di or tri carboxylic acid, even more preferably an unsubstituted organic acid or a hydroxycarboxylic acid different from the Si protecting agents of formula P3, most preferably acetic acid, citric acid, tartaric acid, or a combination thereof, and preferably consists of or comprises acetic, citric acid, or tartaric acid in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight; The acids may be at least partly exchanged by Si protecting agents of formula P3;

[0231] (f) optionally one or more bases, preferably NH4OH or tetramethylammonium hydroxide, most preferably NH4OH, in an amount of from about 0.001 % to about 5 % by weight, more preferably of from about 0.01 % to about 4 % by weight, even more preferably of from about 0.05 % to about 3 % by weight most prefereably of from about 0.1 to about 2 % by weight;

[0232] (I) water as balance to a total of 100 wt.% of the composition in each case; all based on the total weight of the composition, wherein the pH of the composition is preferably of from about 4 to about 8, more preferably of from about 5 to about 7, and wherein the % amounts of the components add to 100 % by weight in each case.

[0233] Application

[0234] In a first embodiment the composition is particularly useful for selectively etching a layer comprising a silicon germanium alloy (SIGe) in the presence of a silicon layer, in particular crystalline Si and preferably in the presence of silicon oxide.

[0235] In a second embodiment the composition is particularly useful for selectively etching a silicon germanium alloy having a first germanium content (SIGehigh) in the presence of silicon germanium alloy having a second germanium content (SIGeiow), wherein the first germanium content is higher than the second germanium content, preferably in the presence of a silicon oxide.

[0236] In the second embodiment, the first germanium content is at least 5% by weight, preferably 10% by weight, more preferably 15% by weight, most preferably 20% by weight higher than the second germanium content. It is particularly preferred to etch SIGe40 against SIGe20.

[0237] 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.

[0238] Accordingly, one embodiment relates to a concentrate or kit including, in one or more containers, one or more components adapted to form the compositions described herein. Preferably, one container comprises the at least one oxidizing agent and a second container comprises the remaining components, e.g., at least one oxidizer, at least one etchant, at least one Si protecting agent, water, and optionally other components described herein, for combining at the fab or the point of use.

[0239] In the use of the compositions described herein, the composition typically is contacted with the device structure for a sufficient time of from about 3 minutes to about 60 minutes, preferably about 5 minutes to about 20 minutes in a batch process and about 20 seconds to about 5 minutes, preferably about 30 seconds to about 3 minutes in a single wafer process.

[0240] In the use of the compositions described herein, the composition typically is contacted with the device structure at temperature in a range of from about 10 °C to about 80 °C, preferably about 20 °C to about 60 °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 SiGe / Si etch ratio. Particularly the SiGe etch rate and the SiGe / Si etch ratio is still very high at temperatures below 30 °C so that the substrates may be processed at room temperature.

[0241] 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., spindry, N2, vapor-dry etc.).

[0242] It may be useful to clean the blanket wafer surfaces for approx 30 s with an aqueous solution containing 0. 1 % to 1 % by weight HF at room temperature, then dipped into UPW for 2-3 s and dried with compressed air. However, by using the composition according to the present invention, it is possible to omit such pretrament with HF.

[0243] The etching composition described herein may be advantagoulsy used for selectively etching a layer comprising SiGe in the presence of a layer comprising or consisting of Si and in the presence of a layer comprising or consisting of silicon oxide. The etching composition described herein may be advantagoulsy used in a process of selectively removing a layer comprising or consisting of a silicon germanium alloy from a surface of a microelectronic device relative to a layer comprising or consisting of Si and a layer comprising or consisting of silicon oxide, the process comprising:

[0244] (a) providing a microelectronic device surface that includes the layer comprising the silicon germanium alloy and the layer comprising or consisting of Si and a layer comprising or consisting of silicon oxide,

[0245] (b) providing a composition as described above or by mixing a concentrate as described above with an oxidizer, and

[0246] (c) contacting the surface with the composition for a time and at a temperature effective to selectively remove the layer comprising silicon-germanium relative to the layer comprising or consisting of Si and the layer comprising or consisting of silicon oxide.

[0247] Preferably the SiGe40 etch rates of the compositions according to the invention are 200 A / min or more, more preferably 300 A / min or more, most preferably 400A / min or more at a temperature of 24 °C. Preferably the SiGe25 etch rates of the compositions according to the invention are 20 A / min or more, more preferably 30 A / min or more, most preferably 50 A / min or more. Preferably the aS! etch rates of the compositions according to the invention are 5 A / min or below, more preferably 3 A / min or below, most preferably 2 A / min. Preferably the etch rates of SIOX, SIN and SION with the compositions according to the invention are 20 A / min or below, more preferably 10 A / min or below. Preferably the SiGe40 / Si selectivity is 200 or more, more preferably 250 or more, most preferably 400 or more. Preferably the SIGe40 / SIGe25 selectivity is 3 or more, more preferably 5 or more, most preferably 10 or more. All numbers and ranges are given for at a temperature of 20 to 30 °C, preferably 24 °C.

[0248] The etching composition described herein may be advantagoulsy used in a process for the manufacture of a semiconductor device, comprising the step of selectively removing silicon-germanium from a surface of a microelectronic device relative to a material comprising or consisting of Si and a material comprising or consisting of silicon oxide.

[0249] The following examples shall further illustrate the present invention without restricting the scope of this invention.

[0250] Examples

[0251] The following substrates prepared by IMEC were used for all experiments unless stated otherwise: aS! (200 A), plasma-treated SIO2 (4500-5000 A), SiGe25 (500 or 1000 A) SiGe40 (1000 A). Plasma treatment is a well known step in the manufacturing of semiconductor substrates and described, e.g., in Solid State Phenomena Vol. 134 (2008) pp 125-128.

[0252] The following Si protecting agents (SiPA) were used:

[0253] 1 Glycidol (comparative)

[0254] 2 Glycerol (comparative) 3 1 ,2-Butanediol (comparative)

[0255] 4 1 ,2-Pentanediol (comparative)

[0256] 5 Lactic acid (comparative)

[0257] 6 (2R)-2-(Methoxymethyl)oxirane

[0258] 7 2-(lsopropoxymethyl)oxirane

[0259] 8 2-(Butoxymethyl)oxirane

[0260] 9 2-[4-(Oxiran-2-ylmethoxy)-butoxymethyl]oxirane

[0261] 10 3-lsopropoxy-1,2-propanediol

[0262] 11 3-(Allyloxy)-1 ,2-propaned iol

[0263] 12 3-[(2-Ethy I hexy l)oxy]- 1 ,2-propanediol

[0264] 13 2-hydroxy-2-methylpropanoic acid

[0265] 14 2-Hydroxy-2-phenylpropanoic acid

[0266] 15 2-Hydroxy-2-phenylacetic acid

[0267] The following further materials were used in electronic grade purity:

[0268] • H2O2(31 %)

[0269] • NH4F (40%)

[0270] • Aqueous NH3(NH4OH 28%)

[0271] • acetic acid

[0272] • trimethoxymethylsilane (TMMS)

[0273] • 2,4,7,9-Tetramethyl-5-decyne-4,7-diol (TMDD)

[0274] All amounts given for the compounds in the compositions are absolute amounts, i.e. excluding water, in the overall mixture.

[0275] Etch bath preparation:

[0276] For etch baths containing a Si protecting agent and acetic acid (Table 1), the following procedure was utilized: The etch bath was prepared by dissolving 8.5 wt% NH4F, 1 .2 wt% acetic acid, 0.16 wt% NH4OH, as well as the Si protecting agent (SiPA), TMMS, and TMDD as indicated in Table 1 in DI water. 2.4 wt% H2O2 was added and the etching bath vessel was set to a temperature of 24 °C + / - 0.5 °C. The pH was adjusted to 6 to 7 with NH4OH if needed. All amounts relate to the pure compounds in the final etch bath even if they are used in dissolved or diluted form.

[0277] For etch baths containing higher concentrations of SiPA (Table 2) the following procedure was employed: The etch bath was prepared by dissolving 8.5 wt% NH4F, 0.16 wt% NH4OH as well as the Si protecting agent (SiPA), TMMS, and TMDD as indicated in Table 1 in DI water. 2.4 wt% H2O2 was added, and the etching bath vessel was set to a temperature of 24 °C + / - 0.5 °C. The pH was adjusted to 6 to 7 with NH4OH if needed. All amounts relate to the pure compounds in the final etch bath even if they are used in dissolved or diluted form.

[0278] Pre-etching:

[0279] Before etching some of the coupons were treated for 60s with 0.5 % HF. The pre-etching was necessary to achieve production-like surface conditions by removing any oxide from the surface. It needs to be emphasized that this step can be omitted in mass production.

[0280] Etching:

[0281] After rinsing with ultra pure water (UPW, electronic grade), the coupons were insert into the etch bath for the material specific times (SiC>2: 300, 600 s; aSi: 300, 600 s; SiGe25: 60 s; SiGe40: 30, 60 s). After etching, the coupons were rinsed with UPW and dried with compressed air.

[0282] The etching rates in A / min were determined by spectroscopic ellipsometry by comparing the initial thickness and the resulting thickness after etching. Average etch rates are presented in case multiple etching times were evaluated for a single material.

[0283] Table 1 displays etching results on blanket wafer coupons with etch baths containing SiPA 1 -12 in combination with acetic acid. Comparative example C1 displays the insufficient protection of SiO 2 and aSi in the absence of any SiPa or TMDD.

[0284] Table 1 n.d. : not determined. Negative values are due to measuring inaccuracies.

[0285] For SiPa 5 and 13-15, addition of another acid, such as acetic acid, can be omitted if the concentration is increased to maintain a pH of 6-7. Examples showcasing the protection of Si in the absence of acetic acid are presented in Table 2. Comparative example C11 underscores the necessity of a sufficiently hydrophobic substitution pattern on the a-hydroxycarboxylic acid, as lactic acid (SiPa 5) does not provide sufficient protection of Si.

[0286] Table 2 In all examples according to the invention the loss of aS! was below 5 A / min. Some embodiments even show a loss of aS! below 3 A / min or even below 2 A / min.

Claims

1. Claims1 . A composition for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content, wherein the first germanium content is higher than the second germanium content, the composition comprising:(a) 0.1 to 10 % by weight of an oxidizing agent, wherein the oxidizing agent is a peroxide;(b) 1 to 14 % by weight of an etchant comprising a source of fluoride ions;(c) 0.0005 to 4 % by weight of an Si protecting agent of formula P1or of formula P2 or of formula P3or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by cocondensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or moreand water;whereinRP1is selected from(a) Ci to C10 alkyl, or(b) C3 to C10 alkenyl; or(c) groupsRP2is selected from H, and a Ci to Ce alkyl,RP3is selected from(a) Ci to C10 alkyl;(b) Ce to C12 aryl or alkylaryl; or(c) Ce to C12 arylalkyl;RP4is selected from RP3or H;XP1is a divalent group selected from a Ci to Ce alkanediyl;XP2is a divalent group selected from a Ci to Ce alkanediyl;RS41is Ci to Ce alkyl which may be unsubstituted or substituted by -NRS61RS62or -OR561;RS42, RS43are independently selected from Ci to Ce alkoxy and Ci to Ce alkyl which both may be unsubstituted or substituted by -NRS61RS62or -OR561;RS51, RS52are independently selected from Ci to Ce alkyl which may be unsubstituted or substituted by - NRS61RS62or -OR561;RS61, RS62are independently selected from H and Ci to Ce alkyl;Xs1is a Ci to Ce alkanediyl; and m is an integer of from 1 to 30.

2. The composition according to claim 1 , wherein the oxidizing agent is hydrogen peroxide.

3. The composition according to anyone of the preceding claims, wherein the etchant is selected from hydrogen fluoride, ammonium fluoride, ammonium bifluoride, triethanolammonium fluoride, diglycolammonium fluoride, methyldiethanolammonium fluoride, tetramethylammonium fluoride, triethylamine tri-hydrofluoride, fluoroboric acid, tetrafluoroboric acid, ammonium tetrafluoroborate, fluoroacetic acid, ammonium fluoroacetate, trifluoroacetic acid, fluorosilicic acid, ammonium fluorosilicate, tetrabutylammonium tetrafluoroborate, or mixtures thereof, preferably hydrogen fluoride or ammonium fluoride.

4. The composition according to anyone of the preceding claims, wherein the Si protecting agent is a compound of formula P1 , wherein RP1is selected from(a) methyl, ethyl, prop-1 -yl or prop-2-yl, or 2 -ethyl-hex-1 -yl, or but-1-yl, or(b) prop-1 -en-3-yl; or(c) a groupRP2is selected from H and a Ci to C4 alkyl,XP1is selected from methanediyl, ethanediyl or propanediyl;XP2is selected from propanediyl, particularly propane-1 ,3-diyl, butanediyl, particularly butane-1 ,4-diyl or hexanediyl, particularly hexane-1 -6-diyl.

5. The composition according to anyone of the preceding claims, wherein the Si protecting agent is a compound of formula P2, wherein RP1is selected from(a) methyl, ethyl, prop-1 -yl or prop-2-yl, or 2 -ethyl-hex-1 -yl, or but-1-yl, or(b) prop-1 -en-3-yl, or(c) a groupRP2is selected from H and a Ci to C4 alkyl;XP1is selected from methanediyl, ethanediyl or propanediyl;XP2is selected from propanediyl, particularly propane-1 ,3-diyl, butanediyl, particularly butane-1, 4-diyl or hexanediyl, particularly hexane-1 -6-diyl.

6. The composition according to anyone of the preceding claims, wherein the Si protecting agent is a compound of formula P3, whereinRP3is selected from(a) methyl, ethyl or propyl,(b) phenyl, toluyl, ethylphenyl, dimethylphenyl or napthyl, or(c) benzyl or phenylethyl;RP4is selected from H, methyl, ethyl or propyl;7. The composition according to anyone of the preceding claims, the composition comprising(i) from 0.001 to 1.5 % by weight, preferably from 0.003 to 1 % by weight of the Si protecting agent of formulaP1 or P2; or(ii) from about 0.1 to about 4 % by weight, even more preferably from about 0.5 to about 3.7 % by weight of the Si protecting agent of formula P3.

8. The composition according to anyone of the preceding claims, comprising from 0.005 to 2 % by weight, preferably from 0.05 to 1 % by weight of the SIOXprotecting agent.

9. The composition according to claim 8, wherein in the the SIOXprotecting agent RS51, RS52, RS53are independently selected from methyl, ethyl, propyl or butyl; RS41is selected from (a) methyl, ethyl, propyl or butyl.

10. The composition according to anyone of the preceding claims, further comprising 0.001 to 3 % by weight of a second Si protecting agent of formula S1(S1), whereinRS1is selected from XS-OH and YS-(CO)-OH;RS2is selected from (I) RS1, (II) H, (ill) Ci to C10 alkyl, (iv) Ci to C10 alkenyl, (v) Ci to C10 alkynyl, and (vi) - Xs1-(O-C2H3RS6)m-ORS6;RS6is selected from H and Ci to Ce alkyl;Xsis selected from a linear or branched Ci to C10 alkanediyl, a linear or branched C2to C10 alkenediyl, a linear or branched C2to C10 alkynediyl, and -Xs1-(O-C2H3RS6)m-;Ysis selected from a chemical bond and Xs.1 1 . The composition according to claim 10, wherein the second Si protecting agent is is a compound of formulaS2whereinRSU, RS21areindenpendetly selected from a Ci to Ce alkyl, preferably from ethyl, propyl, butyl, pentyl and hexylRS12, RS22are independetly selected from H and a Ci to C10 alkyl, preferably H, methyl or ethyl.

12. A concentrate for preparing a composition for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a secondgermanium content, wherein the first germanium content is higher than the second germanium content, the composition comprising:(b) 1 to 14 % by weight of an etchant comprising a source of fluoride ions;(c) 0.0005 to 4 % by weight of an Si protecting agent of formula P1or of formula P2or of formula P3(d) 0 % or 0.001 to 3 % by weight of an SIOXprotecting agent of formula S41or derivatives thereof obtainable by homocondensation of the compounds of formula S41 or by cocondensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or moreand(e) water; whereinRP1is selected from(a) Ci to C10 alkyl, or(b) C3 to C10 alkenyl;(c) and groupsRP2is selected from H, and a Ci to Ce alkyl,RP3is selected from(a) Ci to C10 alkyl;(b) Ce to C12 aryl or alkylaryl; or(c) Ce to C12 arylalkyl;RP4is selected from RP3or H;XP1is a divalent spacer selected from Ci to Ce alkanediyl;XP2is a divalent group selected from a Ci to Ce alkyl;RS41is Ci to Ce alkyl which may be unsubstituted or substituted by -NRS61RS62or -OR561;RS42, RS43are independently selected from Ci to Ce alkoxy and Ci to Ce alkyl which both may be unsubstituted or substituted by -NRS61RS62or -OR561;RS51, RS52are independently selected from Ci to Ce alkyl which may be unsubstituted or substituted by - NRS61RS62or -OR561;RS61, RS62are independently selected from H and Ci to Ce alkyl;Xs1is a Ci to Ce alkanediyl; and m is an integer of from 1 to 30.

13. Use of a composition according to any of claims 1 to 1 1 or a mixture of the concentrate according to claim 12 with a peroxide for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content and optionally a silicon oxide layer, wherein the first germanium content is higher than the second germanium content.

14. A process of selectively removing a first silicon germanium alloy layer having a first germanium content from a surface of a microelectronic device relative to a silicon layer or a second silicon germanium layer having a second germanium content, and optionally a silicon oxide layer, wherein the first germanium content is higher than the second germanium content, the process comprising:(a) providing a microelectronic device surface that includes the layer comprising the silicon germanium alloy and the silicon layer and optionally the silicon oxide layer,(b) providing a composition according to anyone of claims 1 to 1 1 or by mixing a concentrate according to claim 12 with a peroxide, and(c) contacting the surface with the composition for a time and at a temperature effective to selectively remove the layer comprising silicon-germanium relative to the layer comprising or consisting of Si and optionally the silicon oxide layer.

15. A process for the manufacture of a semiconductor device, comprising the process of selectively removing the first silicon germanium alloy layer having the first germanium content from the surface relative to the silicon layer or the second silicon germanium alloy layer having a second germanium content and and optionally a silicon oxide layer according to claim 14.

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