Etching solution for selectively removing silicon-germanium alloy from silicon-germanium / silicon stacks during the manufacture of semiconductor devices

Abstract

The disclosed and claimed subject matter relates to an etching solution comprising (i) water, (ii) at least one oxidizing agent, (iii) at least one fluoride ion source, (iv) at least one multifunctional acid, (v) at least one corrosion-inhibiting surfactant, and (vi) optionally at least one water-miscible organic solvent. The solution is useful for the selective removal of silicon-germanium versus polysilicon from microelectronic devices having these materials thereon during their fabrication.

Description

[Technical field]

[0001] The disclosed and claimed subject matter relates to aqueous etching solutions for use in the manufacture of semiconductor devices. More specifically, the disclosed and claimed subject matter provides aqueous etching solutions that exhibit high etch selectivity of silicon-germanium alloys relative to silicon films with high compatibility with SiO2 in silicon-germanium / silicon composite semiconductor devices. [Background technology]

[0002] Due to the constant miniaturization of ultra-high density integrated circuits and the increasing demand for speed and functionality, conventional planar metal oxide semiconductor field effect transistors (MOSFETs) are facing increasing difficulties such as scaling of gate oxide thickness and electrostatic control of the gate electrode over the channel region. Fin field effect transistors (FinFETs) offer improved control over planar gate MOSFETs by attaching the gate electrode to three sides of a fin-shaped channel.

[0003] GAA MOSFETs are similar to FinFETs, but have the potential for much better electrostatic control over the channel because the gate electrode completely surrounds the channel. In GAA MOSFETs, the channel region is essentially a nanowire. Typically, the nanowire channel has a thickness (or diameter) of a few tens of nanometers (nm) or less and an unconstrained length. The nanowire channel is bridged and anchored in a generally horizontal direction between the much larger source and drain regions of the GAA MOSFET.

[0004] GAA MOSFETs may be fabricated on bulk silicon using fully compatible CMOS technology. A typical fabrication method for forming the channel region in a GAA MOSFET involves epitaxially growing a stack of sacrificial layers (epi-stack) sandwiched between a channel layer on top of a bulk substrate. The sacrificial and channel layers are composed of two different materials so that a selective etch can remove the sacrificial layers.

[0005] As an example, an epi-stack may be formed from alternating layers of silicon (Si) and silicon germanium, with the SiGe layer being the sacrificial layer and the Si layer being the channel layer. The SiGe layer may then be removed by selective etching (e.g., by a wet etching process such as a hydrogen peroxide-containing solution), which may cause unintended trenches in the bulk substrate due to the similarity of the materials that make up the sacrificial layer and the substrate. After the SiGe layer is removed, a Si layer may then be formed into a nanowire channel that is suspended over the trench. A thin gate dielectric is then placed around the Si nanowire channel and over the recessed trench in the substrate. A metal is then placed over the dielectric to form the metal gate electrode of the GAA MOSFET.

[0006] Typically, conventional wet chemical etching solutions for etching SiGe alloys use an oxidizer and an oxide remover. The most common solutions are HF to etch silicon oxide and a solution of hydrogen peroxide (H2O2) and acetic acid (CH3COOH) to oxidize SiGe. The H2O2 / CH3COOH mixture provides a high-quality etching solution for Si with improved smoothness. 1-x Ge x Although highly selective, this chemistry is not effective for removing silicon-germanium on vertical stacks and is not compatible with nitride / oxide masks.

[0007] Applicant's previously filed application (US Patent Application Publication No. 2019 / 0088492) generally discloses etching solutions comprising water, an oxidizer, a water-miscible organic solvent, a fluoride ion source, and an optional surfactant. However, these formulations have not been particularly compatible with SiO2, which is typically present in layers present in silicon and SiGe stacks. These formulations have relatively high SiO2 etch rates, which results in a lower selectivity of SiGe to SiO2. Thus, there is a need to develop formulations with high selectivity of SiGe to Si and high selectivity of SiGe to SiO2, which is addressed by the subject matter disclosed and claimed herein.

[0008] Thus, there is a need in the art for a silicon-germanium etching solution and a method for using the same that provides better control of the etching process during removal of the sacrificial SiGe layer, for example in the formation of Si nanowire channels in GAA MOSFETs, without the above-mentioned drawbacks. Summary of the Invention

[0009] overview This summary section is not intended to identify every embodiment and / or even novel aspect of the disclosed and claimed subject matter. Instead, this summary merely provides a preliminary discussion of various embodiments and corresponding points of novelty over the prior art and known art. For further details and / or possible considerations of the disclosed and claimed subject matter and embodiments, please refer to the detailed description of the present disclosure and corresponding figures, which are discussed further below.

[0010] In one aspect, the disclosed and claimed subject matter provides an etching solution suitable for selective removal of silicon-germanium relative to silicon from microelectronic devices, having good compatibility with SiO2, comprising: (i) Water; (ii) at least one oxidizing agent; (iii) at least one source of fluoride ions; (iv) at least one polyfunctional acid; (v) at least one corrosion-inhibiting surfactant; (vi) at least one silicon oxide etch inhibitor; and (vii) optionally, at least one water-miscible organic solvent; The present invention relates to an etching solution comprising:

[0011] In one other aspect, the disclosed and claimed subject matter provides a method for selectively enhancing the etch rate of silicon-germanium relative to silicon that is compatible with SiO layers on silicon and silicon-germanium containing microelectronic devices, the method comprising: (a) contacting an electronic device containing silicon and silicon-germanium (compound semiconductor) with an etching solution described herein; (b) rinsing the microelectronic (compound semiconductor) device after at least partial removal of the silicon-germanium; and (c) optionally drying the microelectronic device. Comprises, consists essentially of, or consists of.

[0012] Other features and advantages of the disclosed and claimed subject matter will become apparent from the following more detailed description, taken in conjunction with example solutions that illustrate the principles of the disclosed and claimed subject matter.

[0013] The order of discussion of the various steps described herein is provided for clarity. In general, the steps disclosed herein may be performed in any suitable order. In addition, although each of the various features, techniques, configurations, etc. disclosed herein may be discussed in different parts of the disclosure, it is intended that each of these concepts may be performed independently of each other or in any suitable combination with each other. Thus, the subject matter disclosed and claimed may be embodied and considered in many different ways.

[0014] definition To aid in the understanding of the claimed subject matter, reference will now be made to illustrated embodiments and specific language will be used to describe the same. However, no limitation of the claimed subject matter should be understood thereby, and modifications and further variations and further applications of the principles of the invention as illustrated herein will be contemplated as would normally occur to one of ordinary skill in the art to which this disclosure pertains.

[0015] All references cited in this specification, including publications, patent applications, and patents, are herein incorporated by reference to the same extent as if each reference was individually and specifically incorporated by reference and to the same extent as if each reference was set forth in its entirety herein.

[0016] Use of the terms "a" and "an" and "the" and similar referential words in the context of describing the disclosed and claimed subject matter (particularly in the context of the claims below) shall be construed to cover both the singular and the plural, unless otherwise stated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" shall be construed as open-ended terms (i.e., including but not limited to), unless otherwise stated herein. References to ranges herein, unless otherwise stated herein, are intended merely to serve as a shorthand method of referring individually to each separate value in that range, each separate value being incorporated herein as if it were individually set forth herein. All methods described herein may be performed in any suitable order, unless otherwise stated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended merely to better illustrate the disclosed and claimed subject matter and does not limit the scope of the disclosed and claimed subject matter unless and until claimed. No language in the specification should be construed as intending any unclaimed element to be essential to the practice of the disclosed and claimed subject matter.

[0017] Preferred embodiments of the disclosed and claimed subject matter are described herein, including the best mode known to the inventors for carrying out the disclosed and claimed subject matter. Variations of those embodiments will become apparent to those skilled in the art upon reading the following description. The inventors anticipate that such variations will be employed by those skilled in the art as appropriate, and intend that the disclosed and claimed subject matter be practiced otherwise than as specifically described herein. Accordingly, the present disclosure and claimed subject matter as set forth in the appended claims includes all modifications and equivalents of that subject matter. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosed and claimed subject matter, unless otherwise indicated herein or otherwise clearly contrary to context.

[0018] For ease of reference, "microelectronic device" or "semiconductor substrate" refers to semiconductor wafers, flat panel displays, phase change memory devices, solar panels, and other products including solar substrates, photovoltaic cells, and microelectrochemical systems (MEMS) that are manufactured for microelectronic, integrated circuit, or computer chip applications. The term "microelectronic device" is not meant to be limiting in any way and is understood to include any substrate that will ultimately become a microelectronic device or microelectronic assembly. Microelectronic devices or semiconductor substrates include low-k dielectric materials, cell materials, and metals such as Al, Cu, SnAg alloys, W, Ti, TiN, with one or more layers thereon such as polyimide or polybenzoxazole, Si, and other materials.

[0019] "Composite semiconductor device" or "composite microelectronic device" means that the device has one or more materials and / or layers and / or portions of layers present on a non-conductive substrate. The materials include high-k dielectrics and / or low-k dielectrics and / or barrier materials and / or capping materials and / or metal layers and / or others known to one of skill in the art.

[0020] As defined herein, "low-k dielectric material" refers to any material used as a dielectric material in stacked microelectronic devices and having a dielectric constant less than about 3.5. Preferably, the low-k dielectric material includes low polarity materials such as silicon-containing organic polymers, silicon-containing hybrid organic / inorganic materials, organosilicate glass (OSG), TEOS, fluorosilicate glass (FSG), silicon dioxide, and carbon-doped oxide (CDO) glass. It is understood that the low-k dielectric materials may have different densities and different porosities.

[0021] As defined herein, "high-k dielectric material" refers to a material that has a high dielectric constant k (when compared to silicon dioxide). High-k dielectrics can be used to replace silicon dioxide gate dielectrics or other dielectric layers in microelectronic devices. The high-k material can be hafnium dioxide (HfO2), hafnium oxynitride (HfON), zirconium dioxide (ZrO2), zirconium oxynitride (ZrON), aluminum oxide (Al2O3), aluminum oxynitride (AlON), hafnium silicon oxide (HfSiO2), hafnium aluminum oxide (HfAlO), zirconium silicon oxide (ZrSiO2), tantalum dioxide (Ta2O5), aluminum oxide, Y2O3, La2O3, titanium oxide (TiO2), aluminum doped hafnium dioxide, bismuth strontium titanium (BST), or platinum zirconium titanium (PZT).

[0022] As defined herein, the term "barrier material" refers to any material used in the art to seal metal lines, such as copper interconnects, to minimize diffusion of the metal, such as copper, into dielectric materials. Preferred barrier layer materials include tantalum, titanium, titanium tungsten, ruthenium, hafnium and other refractory metals and their nitrides and silicides.

[0023] As used herein, "substantially free" is defined as about 1 wt%, more preferably less than about 0.5 wt%, and most preferably less than about 0.2 wt%. "Substantially free" also includes about 0.0 wt%. The term "free" means 0.0 wt%.

[0024] The term "about" or "approximately" when used in connection with a measurable, numerical variable refers to the value of the indicated variable and all values ​​of the variable that are within experimental error of the indicated value (e.g., a 95% confidence limit for the mean) or within a certain percentage of the indicated value (e.g., ±10%, ±5%), whichever is greater.

[0025] In all solutions where specific components of a solution are discussed with reference to a weight percent range including a lower limit of zero, such components may or may not be present in various specific embodiments of the solution, and in instances where components are present, they may be present in concentrations as low as 0.001 wt% based on the total weight of the solution in which such components are used. Note that unless otherwise stated, all stated weight percentages of components are based on the total weight of the solution. Additionally, unless otherwise stated, all weight percentages are "neat," meaning that they do not include the aqueous solution in which the component is present when added to the solution. Any reference to "at least one" can be substituted with "one or more." "At least one" and / or "one or more" includes "at least two" or "two or more," as well as "at least three" and "three or more," etc.

[0026] The disclosed and claimed etching solution comprises: (i) Water; (ii) at least one oxidizing agent; (iii) at least one source of fluoride ions; (iv) at least one polyfunctional acid; (v) at least one corrosion-inhibiting surfactant; (vi) at least one silane silicon oxide etch inhibitor; and (vii) optionally, at least one water-miscible organic solvent; In a further aspect of this embodiment, the etching solution comprises at least one water-miscible organic solvent.

[0027] In a further embodiment, the etching solution consists essentially of (i) water, (ii) at least one oxidizing agent, (iii) at least one fluoride ion source, (iv) at least one polyfunctional acid, (v) at least one corrosion-inhibiting surfactant, (vi) at least one silane silicon oxide etching inhibitor, and (vii) optionally at least one water-miscible organic solvent. In such an embodiment, the combined amount of (i), (ii), (iii), (iv), (v), (vi) and (if present) (vii) does not equal 100 wt% and may include other components (e.g., additional solvent(s), including water, common additives and / or impurities) that do not significantly change the effectiveness of the cleaning solution. In a further aspect of this embodiment, the etching solution includes at least one water-miscible organic solvent.

[0028] In further embodiments, the etching solution comprises (i) water, (ii) at least one oxidizing agent, (iii) at least one fluoride ion source, (iv) at least one polyfunctional acid, (v) at least one corrosion-inhibiting surfactant, (vi) at least one silane silicon oxide etch inhibitor, and (vii) optionally at least one water-miscible organic solvent. In such embodiments, the combined amount of (i), (ii), (iii), (iv), (v), (vi) and (if present) (vii) is approximately equal to 100 wt%, but includes other minor and / or trace amounts of impurities present in amounts that do not significantly change the effectiveness of the solution. For example, in one such embodiment, the etching solution may contain 2 wt% or less of impurities. In one other embodiment, the etching solution may contain 1 wt% or less of impurities. In a further embodiment, the etching solution may contain 0.05 wt% or less of impurities. In a further aspect of this embodiment, the etching solution comprises at least one water-miscible organic solvent.

[0029] When referring to the etching solutions described herein in terms of wt%, in no case is it understood that the wt% of all components, including non-essential components, such as impurities, total more than 100 wt%. In a solution "consisting essentially" of the components described, such components may be added up to 100 wt% of the solution, or may be added up to less than 100 wt%. When a component is added up to 100 wt%, such a solution may contain some small amount of non-essential contaminants or impurities. For example, in one such embodiment, the solution may contain 2 wt% or less of impurities, and in one other embodiment, the rinse may contain 1 wt% or less of impurities. In a further embodiment, the solution may contain 0.05 wt% or less of impurities. In other such embodiments, the components may form at least 90 wt%, more preferably at least 95 wt%, more preferably at least 99 wt%, more preferably at least 99.5 wt%, and most preferably at least 99.8 wt%, and may include other components that do not affect the performance of the wet etchant. It is understood that in the absence of other significant non-essential impurity components, the solution of all essential components essentially totals 100 wt%.

[0030] Detailed Description Both the foregoing general description and the following detailed description are illustrative and exemplary and are not intended to limit the claimed subject matter. The objects, features, advantages and ideas of the disclosed subject matter will be apparent to those skilled in the art from the description provided herein, and the disclosed subject matter can be readily implemented by those skilled in the art based on the description found herein. Any "preferred embodiments" and / or example descriptions illustrating preferred modes for implementing the disclosed subject matter are included for illustrative purposes and are not intended to limit the scope of the claims.

[0031] It will also be apparent to those skilled in the art that various modifications can be made in how the disclosed subject matter is implemented based on the embodiments described herein without departing from the spirit and scope of the subject matter disclosed herein.

[0032] As stated above, the disclosed and claimed subject matter provides an etching solution suitable for selective removal of silicon-germanium relative to silicon from microelectronic devices, having good compatibility with SiO2, comprising: (i) Water; (ii) at least one oxidizing agent; (iii) at least one source of fluoride ions; (iv) at least one polyfunctional acid; (v) at least one corrosion-inhibiting surfactant; (vi) at least one silane silicon oxide etch inhibitor; and (vii) optionally, at least one water-miscible organic solvent; The present invention relates to an etching solution comprising:

[0033] In some embodiments, the etching solutions disclosed herein are formulated to be substantially free or free of inorganic bases and / or quaternary ammonium compounds, including quaternary ammonium fluorides and / or quaternary ammonium hydroxides, e.g., the solutions may be free of one or more of the following: tetramethylammonium fluoride, tetraethylammonium fluoride, methyltriethylammonium fluoride, and tetrabutylammonium fluoride, tetramethylammonium hydroxide, tetraethylammonium hydroxide, methyltriethylammonium hydroxide, and / or tetrabutylammonium hydroxide.

[0034] (i) Water As stated above, the etching solution of the disclosed and claimed subject matter includes water. In the disclosed and claimed subject matter, water functions in various ways, such as as a carrier of components, as an aid in the removal of residues, as a viscosity modifier for the solution, and as a diluent to dissolve one or more components of the solution. Preferably, the water used in the cleaning solution is deionized (DI) water. The range of water described in the following paragraphs includes all of the water in the solution, from any source.

[0035] For most applications, the weight percent of water in the solution will be within a range having a beginning and an end point selected from the following number groups: 0.5, 1, 5, 10, 15, 20, 25, 30, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, and 90. Examples of ranges of water that can be used in the solution include, for example, about 0.5 wt% to about 90 wt%, 1 wt% to about 85 wt%, about 5.0 wt% to about 80 wt%, about 10 wt% to about 70 wt%, or about 40 wt% to about 80 wt% water. Still other preferred embodiments of the disclosed and claimed subject matter include water in an amount to achieve the desired weight percentage of the other ingredients.

[0036] In one embodiment, the solution comprises about 40 wt% to about 90 wt% water. In one embodiment, the solution comprises about 40 wt% to about 90 wt% water. In one embodiment, the solution comprises about 50 wt% to about 80 wt% water. In one embodiment, the solution comprises about 60 to 80 wt% water. In one embodiment, the solution comprises about 70 wt% to about 75 wt% water. In one embodiment, the solution comprises about 5 wt% water. In one embodiment, the solution comprises about 10 wt% water. In one embodiment, the solution comprises about 15 wt% water. In one embodiment, the solution comprises about 20 wt% water. In one embodiment, the solution comprises about 25 wt% water. In one embodiment, the solution comprises about 30 wt% water. In one embodiment, the solution comprises about 35 wt% water. In one embodiment, the solution comprises about 40 wt% water. In one embodiment, the solution comprises about 45 wt% water. In one embodiment, the solution comprises about 50 wt% water. In one embodiment, the solution comprises about 55 wt% water. In one embodiment, the solution comprises about 60 wt% water. In one embodiment, the solution comprises about 65 wt% water. In one embodiment, the solution comprises about 70 wt% water. In one embodiment, the solution comprises about 75 wt% water. In one embodiment, the solution comprises about 80 wt% water. In one embodiment, the solution comprises about 85 wt% water. In one embodiment, the solution comprises about 90 wt% water.

[0037] (ii) Oxidizing agent The etching solutions of the disclosed and claimed subject matter include an oxidizing agent (also referred to as an oxidizer). The oxidizing agent functions primarily to etch silicon-germanium alloys by forming the corresponding (i.e., germanium or silicon) oxide. The oxidizing agent may be any suitable oxidizing agent. Suitable oxidizing agents include, but are not limited to, one or more peroxide compounds, i.e., compounds that contain at least one peroxy group (-OO-). Suitable peroxide compounds include, for example, peroxides, persulfates (e.g., monopersulfates and dipersulfates), percarbonates, and acids thereof, and salts thereof, and mixtures thereof. Other suitable oxidizing agents include, for example, oxyhalides (e.g., iodides, periodides, and acids thereof, and mixtures thereof, etc.), perboric acid, perborates, peracids (e.g., peracetic acid, perbenzoic acid, salts thereof, mixtures thereof, etc.), permanganic acid, cerium compounds, ferricyanides (e.g., potassium ferricyanide), mixtures thereof, and the like.

[0038] In some embodiments, the oxidizing agent includes, but is not limited to, hydrogen peroxide, periodic acid, potassium iodate, potassium permanganate, ammonium persulfate, ammonium molybdate, ferric nitrate, nitric acid, potassium nitrate, ammonia, and mixtures thereof. In yet other embodiments, the oxidizing agent includes hydrogen peroxide and urea hydrogen peroxide. In some embodiments, the oxidizing agent includes hydrogen peroxide.

[0039] In some embodiments, the weight percent of the oxidizer in the etching solution (undiluted) is within a range having a beginning and an end point selected from the following number groups: 0.5, 1, 1.5, 2, 2.5, 3, 5, 8, 10, 12, 15, 20, 25, 30, 40, 45, 50, 55, and 60. In some embodiments, the oxidizer is present in the solution in an amount of about 0.5 wt% to about 30 wt%, about 0.5 wt% to about 20 wt%, about 1.5 wt% to about 20 wt%, wt% to about 20 wt%, 3 wt% to about 15 wt%, 6 wt% to about 15 wt%, 6 wt% to about 20 wt%, or 3 wt% to about 20 wt% of the solution. In one alternative embodiment, the oxidizer is present in the solution in an amount of about 3.0 wt% to about 20 wt%. In another embodiment, the oxidizing agent is present in the solution in an amount of about 5.0 wt% to about 30 wt%. In another embodiment, the oxidizing agent is present in the solution in an amount of about 5.0 wt% to about 20 wt%. In another embodiment, the oxidizing agent is present in the solution in an amount of about 10 wt% to about 20 wt%. In another embodiment, the oxidizing agent is present in the solution in an amount of about 10 wt% to about 15 wt%. In another embodiment, the oxidizing agent is present in the solution in an amount of about 10 wt% to about 30 wt%. In another embodiment, the oxidizing agent is present in the solution in an amount of about 20 wt% to about 30 wt%.

[0040] (iii) A source of fluoride ions The etching solution of the present disclosure further comprises one or more fluoride ion sources. The fluoride ions function primarily to aid in the removal of silicon or germanium oxides formed by the action of the oxidizing agent. Exemplary compounds that provide a fluoride ion source according to the disclosed and claimed subject matter include hydrofluoric acid, ammonium fluoride, quaternary ammonium fluorides, fluoroborates, fluoroboric acid, tetrabutylammonium tetrafluoroborate, aluminum hexafluoride, and fluorine-containing fluorides of the formula: R 1 NR 2 R 3 R 4 F (In the formula, R 1 , R 2 , R 3 and R 4Each represents H or a (C1-C4) alkyl group. Typically, R 1 , R 2 , R 3 and R 4 The total number of carbon atoms in the group is not more than 12. Examples of fluoride salts of aliphatic primary, secondary or tertiary amines are, for example, tetramethylammonium fluoride, tetraethylammonium fluoride, methyltriethylammonium fluoride and tetrabutylammonium fluoride.

[0041] In selecting a fluoride ion source, consideration should be given to whether the fluoride ion source releases ions that have a detrimental effect on the surface being cleaned. For example, in cleaning semiconductor components, the presence of sodium or calcium ions in the cleaning solution may have a detrimental effect on the surface of the components. In some embodiments, the fluoride ion source is ammonium fluoride or ammonium bifluoride.

[0042] Without being bound by theory, it is believed that the compound used as the fluoride ion source in the cleaning solution is included in an amount of about 0.01 wt% to about 8 wt% or about 0.01 wt% to about 20 wt% of 40% ammonium fluoride, or in an amount stoichiometrically equivalent thereto, for many applications. Preferably, the compound includes about 0.02 wt% to about 8 wt%, more preferably about 0.02 wt% to about 6 wt%, even more preferably about 1 wt% to about 8 wt%, and most preferably about 0.025 wt% to about 5 wt% of about 40% ammonium fluoride. In some embodiments, the solution includes about 0.01 wt% to about 8 wt% or about 0.01 wt% to about 7 wt% of the fluoride ion source, which may be provided by a 40% ammonium fluoride solution. Preferably, the compound comprises about 0.02 wt% to about 6 wt% of the fluoride ion source, most preferably about 0.025 wt% to about 5 wt% of the fluoride ion source, about 0.04 wt% to about 2.5 wt% of the fluoride ion source or about 0.02 wt% to about 1.5 wt% of the fluoride ion source, or about 0.05 wt% to about 15 wt% of a 40% ammonium fluoride solution, most preferably about 0.0625 wt% to about 12.5 wt% or about 0.1 wt% to about 6.25 wt% of a 40% ammonium fluoride solution. However, it is understood that the amount of fluoride ion used typically depends on the particular substrate to be cleaned. For example, in certain cleaning applications, the amount of fluoride ion may be relatively high when the substrate to be cleaned, including a dielectric material, has a high resistance to fluoride etching. Conversely, in other applications, the amount of fluoride ions should be relatively low, for example when the cleaning substrate, including a dielectric material, has low resistance to fluoride etching.

[0043] For clarity, based solely on the addition of the fluoride ion source (undiluted), the fluoride ion source in the cleaning solution is included in weight percents within a range having beginning and end points selected from the following list of weight percents: 0.001, 0.0016, 0.002, 0.0025, 0.004, 0.008, 0.01, 0.02, 0.025, 0.04, 0.05, 0.1, 0.4, 0.6, 1, 2, 2.4, 2.5, 2.8, 3.2, 5, 6, 10, 12, 15, and 20. For example, the amount of fluoride ion source in the solution (undiluted) may be from about 0.004 wt% to about 3.2 wt% or from about 0.004 wt% to about 2.8 wt%. The solution comprises about 0.008 wt% to about 3.2 wt%, about 0.008 wt% to about 2.4 wt%, about 0.4 wt% to about 3.2 wt%, about 0.01 wt% to about 2 wt%, 0.01 wt% to about 10 wt%, or 0.01 wt% to about 5 wt% of the fluoride ion source. In some embodiments, the solution comprises about 0.004 wt% to about 3.2 wt% of the fluoride ion source. The solution comprises about 0.001 wt% to about 2 wt%, about 0.0016 wt% to about 1 wt%, about 0.002 wt% to about 6 wt%, about 0.0025 wt% to about 5 wt%, or about 0.04 wt% to about 0.025 wt% of the fluoride ion source. In still other embodiments, the solution comprises from about 0.05 wt % to about 20 wt %, from about 0.1 wt % to about 15 wt %, from about 0.1 wt % to about 20 wt %, from about 0.01 wt % to about 20 wt %, from about 0.1 wt % to about 10 wt %, from about 0.1 wt % to about 5 wt %, from about 0.6 wt % to about 12 wt %, from about 1 wt % to about 20 wt %, from about 1 wt % to about 15 wt %, or from about 1 wt % to about 10 wt % of the fluoride ion source based on the neat fluoride ion source.

[0044] (iv) Polyfunctional acids The etching solution includes one or more multifunctional acids, including both organic and inorganic acids. Multifunctional organic acids refer to acids or multi-acids that have more than one carboxylic acid group, including, but not limited to, (i) dicarboxylic acids (e.g., malonic acid, malic acid, etc.), dicarboxylic acids with aromatic moieties (e.g., phthalic acid, etc.), and combinations thereof; and (ii) tricarboxylic acids (e.g., citric acid, etc.), tricarboxylic acids with aromatic moieties (e.g., trimellitic acid, etc.), and combinations thereof. Multifunctional inorganic acids refer to multiprotic acids (i.e., more than one ionizable H per molecule, such as H2SO4), that have the ability to lose more than one proton per molecule in an acid-base reaction. + An acid having 1 or 2 atoms.

[0045] In one embodiment, the polyfunctional acid comprises only one or more polyfunctional organic acids (i.e., does not comprise polyfunctional inorganic acids). In another embodiment, the polyfunctional acid comprises only one or more polyfunctional inorganic acids (i.e., does not comprise polyfunctional organic acids). In another embodiment, the polyfunctional acid comprises both one or more polyfunctional organic acids and one or more polyfunctional inorganic acids.

[0046] polyfunctional organic acids Useful dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0047] In some embodiments, the polyfunctional organic acid is a multiprotic acid having at least three carboxylic acid groups. Such acids have at least a second and a third dissociation constant, each higher than its respective previous constant. This indicates that the acid is more likely to lose the first proton than the second proton, since the first proton separates from the ion with one negative charge and the second proton separates from the ion with two negative charges. Without being bound by theory, it is believed that the two negative charges strongly attract the proton back to the acid ion. A similar relationship exists between the second and third separated protons. Thus, multifunctional acids, such as those having at least three carboxylic acid groups, are useful for controlling the pH of a solution, particularly at a pH corresponding to their higher pKa values. For example, in addition to having a pKa value of about 5 to about 7, preferred multiprotic acids of the disclosed and claimed subject matter have multiple pKa values, with the highest pKa being about 3 to about 7.

[0048] Multiprotic acids having at least three carboxylic acid groups according to the disclosed and claimed subject matter have high compatibility with polyhydrogen solvents. Examples of preferred multiprotic acids include tricarboxylic acids (e.g., citric acid, 2-methylpropane-1,2,3-triscarboxylic acid, benzene-1,2,3-tricarboxylic acid [hemimellitic acid], propane-1,2,3-tricarboxylic acid [tricarvallic acid], 1,cis-2,3-propenetricarboxylic acid [aconitic acid], etc.), tetracarboxylic acids (e.g., butane-1,2,3,4-tetracarboxylic acid, cyclopentanetetra-1,2,3,4-carboxylic acid, benzene-1,2,4,5-tetracarboxylic acid [pyromellitic acid], etc.), pentacarboxylic acids (e.g., benzenepentacarboxylic acid), and hexacarboxylic acids (e.g., benzenehexacarboxylic acid [mellitic acid]), etc. The pKa values ​​of each of these acids are shown in Table 1. Certain preferred multiprotic acids include tricarboxylic acids, with citric acid being most preferred. Table 1 [Table 1]

[0049] Citric acid, a preferred multiprotic acid, is a tricarboxylic acid having three pKa's: 3.13, 4.76, and 6.40, corresponding to the trihydrogen citrate, dihydrogen citrate, and monohydrogen citrate ions, respectively. In certain preferred embodiments of the disclosed and claimed subject matter, the polyfunctional organic acid comprises a salt of citric acid, with particularly preferred examples including triammonium citrate (TAC) and aqueous solutions of citric acid.

[0050] In alternative embodiments, other polyfunctional organic acids (although citric acid has been described), their respective salts, typically the ammonium salts of the respective polyfunctional acids, such as malonic acid and ammonium malonate; oxalic acid and ammonium oxalate; and succinic acid and ammonium succinate, can be used in the solutions of the disclosed and claimed subject matter.

[0051] polyfunctional inorganic acid Useful polyfunctional inorganic acids (ie, multiprotic acids) include one or more of those set forth in the table below. Table 2 [Table 2]

[0052] In one embodiment, the polyfunctional inorganic acid comprises H3PO4.

[0053] The amount of polyfunctional acid in the solution of the disclosed and claimed subject matter may be any range of weight percent with starting and ending points selected from the following: 0.1, 0.25, 0.4, 0.5, 0.6, 0.8, 0.9, 1, 1.5, 2, 3, 4, and 5, such as about 10 wt% to about 30 wt%, about 20 wt% to about 30 wt%, about 0.5 wt% to about 10 wt%, about 0.5 wt% to about 5 wt%, about 0.5 wt% to about 8 wt%, about 0.5 wt% to about 3 wt%, about 0.1 wt% to 5 wt%, preferably 0.25 wt% to about 3 wt%, and more preferably 0.5 wt% to 2.0 wt% of the solution, based on the total weight of the solution. In one embodiment, the amount of polyfunctional acid in the solution is about 0.5 wt% to about 1.5 wt%.

[0054] For example, the conjugate base may be present in the solution at a weight percentage within any range having a beginning and an end point selected from the following: 0.1, 0.25, 0.4, 0.5, 0.6, 0.8, 0.9, 1, 1.5, 2, 3, 4, and 5, based on the total weight of the solution, such as about 10 wt% to about 30 wt%, about 20 wt% to about 30 wt%, about 0.5 wt% to about 10 wt%, about 0.5 wt% to about 5 wt%, about 0.5 wt% to about 8 wt%, about 0.5 wt% to about 3 wt%, about 0.1 wt% to 5 wt%, preferably 0.25 wt% to 3 wt%, and more preferably 0.5 wt% to 2.0 wt% of the solution. In some embodiments, the conjugate base (e.g., an ammonium salt) for the polyfunctional acid, if present, may be present in a weight ratio of from 10:1 to 1:10, or from 5:1 to 1:5, relative to the amount of polyfunctional acid present in solution.

[0055] Preferably, the disclosed etching solution is acetic acid, in some embodiments, the pH is from about 2 to about 7 or from about 4 to about 6.5.

[0056] (v) Corrosion-inhibiting surfactants The etching solution of the disclosed and claimed subject matter comprises at least one corrosion-inhibiting surfactant. The corrosion-inhibiting surfactant functions to protect silicon from etching. Surfactants for use in the solutions described herein include, but are not limited to, amphoteric salts, cationic surfactants, anionic surfactants, zwitterionic surfactants, nonionic surfactants, and combinations thereof, including, but not limited to, bis(2-ethylhexyl)phosphate, perfluoroheptanoic acid, perfluorodecanoic acid, trifluoromethanesulfonic acid, phosphonoacetic acid, dodecenyl succinic acid, dioctadecyl hydrogen phosphate, octadecyl hydrogen phosphate, dodecylamine, dodecenyl succinic acid, monodiethanolamide, lauric acid, palmitic acid, oleic acid, juniperic acid, 12 hydroxystearic acid, dodecyl phosphate.

[0057] Contemplated non-ionic surfactants include, but are not limited to, polyoxyethylene lauryl ethers (Emalmin NL-100 (Sanyo), Brij 30, Brij 98, Brij 35), dodecenyl succinic acid monodiethanolamide (DSDA, Sanyo), ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol (Tetronic 90R4), polyethylene glycols (e.g. PEG 400), polypropylene glycols, polyethylene or polypropylene glycol ethers, ethylene oxide and propylene oxide based block copolymers (Newpole PE-68 (Sanyo), Pluronic® L31, Pluronic® 31R1, Pluronic® L61, Pluronic® F-127), polyoxypropylene sucrose ethers (SN008S, Sanyo), t-octylphenoxy polyethoxyethanol (Triton®), X100), 10-ethoxy-9,9-dimethyldecan-1-amine (TRITON® CF-32), polyoxyethylene (9) nonylphenyl ether, branched (IGEPAL CO-250), polyoxyethylene (40) nonylphenyl ether, branched (IGEPAL CO-890), polyoxyethylene sorbitol hexaoleate, polyoxyethylene sorbitol tetraoleate, polyethylene glycol sorbitan monooleate (Tween® 80), sorbitan monooleate (Span 80), combinations of Tween® 80 and Span 80, alcohol alkoxylates (e.g., Plurafac RA-20), alkyl-polyglucosides, ethyl perfluorobutyrate, 1,1,3,3,5,5-hexamethyl-1,5-bis[2-(5-norbornen-2-yl)ethyl]trisiloxane, SIS6952.0 (Siliclad, Gelest), siloxane modified polysilazanes such as PP1-SG10 Siliclac Glide 10 (Gelest), silicone-polyether copolymers such as Silwet L-77 (Setre Chemical Company), Silwet ECO Spreader (Momentive), as well as ethoxylated fluorosurfactants (ZONYL® FSO-100, ZONYL® FSN-100), nonionic polyoxyethylene substituted acetylenic glycol surfactants commercially available under the general trade name SURFYNOL® (e.g., SURFYNOL® 104, 82, 465 and 485). One preferred surfactant is SURFYNOL® 485.

[0058] Contemplated cationic surfactants include, but are not limited to, cetyltrimethylammonium bromide (CTAB), heptadecanefluorooctanesulfonic acid, tetraethylammonium, stearyltrimethylammonium chloride (Econol TMS-28, Sanyo), 4-(4-diethylaminophenylazo)-1-(4-nitrobenzyl)pyridium bromide, cetylpyridium chloride monohydrate, benzalkonium chloride, benzethonium chloride, benzyl dimethyl dodecyl ammonium chloride, benzyl dimethyl hexadecyl ammonium chloride, hexadecyl trimethyl ammonium bromide, dimethyl dioctadecyl ammonium chloride, dodecyl trimethyl ammonium chloride, hexadecyl trimethyl ammonium p-toluenesulfonate, didodecyl dimethyl ammonium bromide, di(hydrogenated tallow) dimethyl ammonium chloride, tetraheptyl ammonium bromide, tetrakis(decyl) ammonium bromide, Aliquat® 336 and oxyphenonium bromide, guanidine hydrochloride. (C(NH2)3Cl) or triflate salts such as tetrabutylammonium trifluoromethanesulfonate, dimethyldioctadecylammonium chloride, dimethylzoihexadecylammonium bromide, and di(hydrogenated tallow)dimethylammonium chloride (e.g. Arquad 2HT-75, Akzo Nobel).

[0059] In some embodiments, the cationic surfactant, when used, comprises a polyalkyleneimine. Preferably, the polyalkyleneimine is polyethyleneimine (PEI). Any PEI can be used, but it is preferred that homopolymeric polyethyleneimine is used. The PEI can be branched or linear, but is preferably branched.

[0060] The PEI used may have any formula weight (FW) for efficacy, but preferably the PEI has a smaller formula weight (FW). In one embodiment, the PEI has a FW of 100-50,000, 400-25,000, 800-10,000, or 1,000-3,000.

[0061] In one embodiment, the polyalkyleneimine comprises polyethyleneimine (PEI), preferably the PEI comprises less than 1 wt% of the solution, preferably less than 0.5 wt%, less than 0.25 wt%, or from about 0.1 wt% to about 1 wt% of the solution. Preferably, the PEI has a molecular weight of 100-2500, preferably 200-1500, and most preferably 400-1200.

[0062] In preferred embodiments, the polyalkyleneimine has a molecular weight of 100 to 2500, 200 to 1500, 400 to 1200 or 700 to 900. Particularly suitable is a molecular weight of 800. The molecular weight is suitably determined by light scattering techniques known in the art.

[0063] Polyethylenimines are commercially available, for example Lupasol® 800 supplied by BASF.

[0064] Contemplated anionic surfactants include, but are not limited to, ammonium polyacrylates (e.g., DARVAN 821A), modified polyacrylic acids in water (e.g., SOKALAN CP10S), phosphate polyetheresters (e.g., TRITON® H-55), decylphosphonic acid, dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, dodecylbenzenesulfonic acid, poly(acrylic acid sodium salt), sodium polyoxyethylene lauryl ether, sodium dihexyl sulfosuccinate, dicyclohexyl sulfosuccinic acid sodium salt, sodium 7-ethyl-2-methyl-4-undecyl sulfate (Tergitol 4), SODOSIL RM02, and phosphate fluorosurfactants such as Zonyl® FSJ and ZONYL® UR.

[0065] Zwitterionic surfactants include, but are not limited to, acetylenic diols or modified acetylenic diols (e.g., SURFONYL 504), cocamidopropyl betaine, ethylene oxide alkylamines (AOA-8, Sanyo), N,N-dimethyldodecylamine N-oxide, sodium cocamine propionate (LebonApl-D, Sanyo), 3-(N,N-dimethylmyristylammonio)propanesulfonate, and (3-(4-heptyl)phenyl-3-hydroxypropyl)dimethylammoniopropanesulfonate. Preferably, the at least one surfactant includes dodecylbenzenesulfonic acid, dodecylphosphonic acid, dodecylphosphate, TRITON® X-100, SOKALAN CP10S, PEG 400, and PLURONIC® F-127. In one embodiment, a preferred surfactant is an ethoxylated acetylenic diol, such as SURFONYL® 485.

[0066] In some embodiments, a mixture of surfactants may be used in the solution of the disclosed and claimed subject matter.For example, in some of the solutions of the disclosed and claimed subject matter, the surfactant comprises a mixture of acetylenic diol or modified acetylenic diol and polyalkyleneimine.In one embodiment, the solution comprises two or more of PEG-400, Lupasol® 800 and Surfynol® 485.

[0067] When present, the surfactant is present in a total amount ranging from about 0.001 wt% to about 1 wt%, preferably from about 0.1 wt% to about 1 wt%, based on the total weight of the solution. Alternatively, without being bound by theory, for some applications, when present, the one or more surfactants comprise about 0.1 wt% to about 15 wt%, about 0.1 wt% to about 10 wt%, about 0.5 wt% to about 5 wt%, about 0.1 wt% to about 1 wt%, or about 0.5 wt% to about 1 wt% of the solution. In alternative embodiments, the weight percentage of the surfactant in the solution may be within any range with a starting point and an end point selected from the following, based on the total weight of the solution: 0.1, 0.2, 0.5, 0.9, 1, 1.5, 2, 4, 5, 8, 10, 12, and 15.

[0068] (vi) Silane silicon oxide etch inhibitors The etching solutions of the disclosed and claimed subject matter include at least one silane silicon oxide etch inhibitor. Examples of suitable and / or preferred silane silicon oxide etch inhibitors include methyltrimethoxysilane, ethyltrimethoxysilane, triethoxy(ethyl)silane, vinyltrimethoxysilane, trimethoxyphenylsilane, triethoxymethylsilane, trimethoxy(octyl)silane, propyltrimethoxysilane, isobutyl(trimethoxy)silane, trimethoxysilane, n-propyltriethoxysilane, trimethoxy(octadecyl)silane, hexadecyltrimethoxysilane, methyl(tripropyl)silane, ethyl(tripropyl)silane, and propyl(tripropyl)silane.

[0069] In one embodiment, the at least one silane silicon oxide etch inhibitor comprises silicic acid.

[0070] In one embodiment, the at least one silane silicon oxide etch inhibitor has Formula I: [ka] Formula I (In the formula, (i)R a and R b each of R is -C3H6-; 1 , R 2 , R 4 and R 5 is —H, and (iii) m=0 to 20. In one aspect of this embodiment, the silicon-containing compound of formula I has the formula: (hereinafter “Si compound”): [ka] Si compound 1

[0071] In one embodiment, the at least one silane silicon oxide etch inhibitor comprises methyltrimethoxysilane.

[0072] The amount of at least one silane silicon oxide etch inhibitor in the solution of the disclosed and claimed subject matter can be within any range having a beginning and an end point selected from the following: 0.1, 0.25, 0.4, 0.5, 0.6, 0.8, 0.9, 1, 1.5, 2, 3, 4, and 5, based on the total weight of the solution, such as about 10 wt% to about 30 wt%, about 20 wt% to about 30 wt%, about 0.5 wt% to about 10 wt%, about 0.5 wt% to about 5 wt%, about 0.5 wt% to about 8 wt%, about 0.5 wt% to about 3 wt%, about 0.1 wt% to 5 wt%, preferably 0.25 wt% to 3 wt%, and more preferably 0.5 wt% to 2.0 wt%. In one embodiment, the amount of polyfunctional acid in the solution is about 0.5 wt% to about 1.5 wt%. In one embodiment, the amount of the at least one silane silicon oxide etch inhibitor in the solution is from about 0.01 wt % to about 1.0 wt %.

[0073] (vii) an optional water-miscible organic solvent The etching solution of the disclosed and claimed subject matter may optionally include at least one water-miscible organic solvent. Examples of water-miscible organic solvents that may be used are ethylene glycol, propylene glycol, butyl diglycol, 1,4-butanediol, tripropylene glycol methyl ether, propylene glycol propyl ether, diethylene glycol n-butyl ether (e.g., commercially available under the trade name Dowanol DB), hexyloxypropylamine, poly(oxyethylene)diamine, dimethylsulfoxide, tetrahydrofurfuryl alcohol, glycerol, alcohols, sulfoxides, sulfolane, or mixtures thereof. The preferred solvent may be an alcohol, a diol, or a mixture thereof. In some embodiments, the preferred solvent may be sulfolane or a sulfoxide, such as dimethylsulfoxide. In some embodiments, the preferred solvent is a diol, such as propylene glycol. In other embodiments, the preferred solvent is a glycol ether.

[0074] In some embodiments of the disclosed and claimed subject matter, the water-miscible organic solvent comprises a glycol ether. Examples of glycol ethers include butyl diglycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monobenzyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, polyethylene glycol monomethyl ether, diethylene glycol methyl ethyl ether, The at least one water-miscible solvent includes propylene glycol (PG), triethylene glycol ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol monobutyl ether, propylene glycol, monopropyl ether, dipropylene glycol monomethyl ether (DPM), dipropylene glycol monopropyl ether, dipropylene glycol monoisopropyl ether, dipropylene monobutyl ether, dipropylene glycol diisopropyl ether, tripropylene glycol monomethyl ether, 1-methoxy-2-butanol, 2-methoxy-1-butanol, 2-methoxy-2-methylbutanol, 1,1-dimethoxyethane, and 2-(2-butoxyethoxy)ethanol. In one embodiment, the at least one water-miscible solvent includes propylene glycol (PG). In one embodiment, the at least one water-miscible solvent includes ethylene glycol (EG). In one embodiment, the at least one water-miscible solvent comprises dipropylene glycol monomethyl ether (DPM).

[0075] In some embodiments, the water-miscible organic solvent in the solution of the disclosed and claimed subject matter comprises a glycol ether, such as butyl diglycol or dipropylene glycol monomethyl ether. In some embodiments, the preferred solvent may be an alcohol, a diol, or a mixture thereof. In some embodiments, the preferred solvent is a diol, such as propylene glycol. In other embodiments, the preferred solvent is a glycol ether, such as dibutyl glycol. In some embodiments, the preferred solvent may be sulfolane or a sulfoxide, such as dimethyl sulfoxide. Mixtures of these and other solvents may be used.

[0076] For many applications, the amount of water-miscible organic solvent in the solution can be within a range having a beginning and ending point selected from the following list of weight percent: 0.5, 1, 5, 7, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50, 55, 59.5, 60, 65, 70, 75 and 80. Examples of ranges of such solvents include about 0.5 wt% to about 59.5 wt%, about 1 wt% to about 50 wt%, about 1 wt% to about 40 wt%, about 0.5 wt% to about 30 wt%, about 1 wt% to about 30 wt%, about 5 wt% to about 30 wt%, about 5 wt% to about 15 wt%, about 7 wt% to about 12 wt%, about 7 wt% to about 80 wt%, about 20 wt% to about 60 wt%, about 10 wt% to about 50 wt%, about 10 wt% to about 45 wt%, about 10 wt% to about 35 wt%, about 15 wt% to about 50 wt%, or about 15 wt% to about 35 wt% of the solution. In one embodiment, the water-miscible organic solvent in the solution is about 3 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 3 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 5 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 10 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 15 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 20 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 25 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 30 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 35 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 40 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 45 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 50 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 55 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 60 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 65 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 70 wt%. In one embodiment, the water-miscible organic solvent in the solution is about 75 wt%.

[0077] Other Optional Ingredients The etching solutions of the disclosed and claimed subject matter may further include one or more of the following additives: chelating agents, chemical modifiers, dyes, biocides, and other additives. The one or more additives may be added to the extent that they do not adversely affect the performance of the solution.

[0078] Another optional component that can be used in the etching solution is a metal chelating agent, which can function to increase the capacity of the solution, retain metals in the solution, and enhance dissolution of metal residues. Typical examples of chelating agents useful for this purpose are the following organic acids and their isomers and salts: ethylenediaminetetraacetic acid (EDTA), butylenediaminetetraacetic acid, (1,2-cyclohexylenediamine)tetraacetic acid (CyDTA), diethylenetriaminepentaacetic acid (DETPA), ethylenediaminetetrapropionic acid, (hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), N,N,N',N'-ethylenediaminetetra(methylenephosphonic acid). Acid (EDTMP), triethylenetetraaminehexaacetic acid (TTHA), 1,3-diamino-2-hydroxypropane-N,N,N'N'-tetraacetic acid (DHPTA), methyliminodiacetic acid, propylenediaminetetraacetic acid, nitrotriacetic acid (NTA), citric acid, tartaric acid, gluconic acid, saccharic acid, glyceric acid, oxalic acid, phthalic acid, maleic acid, mandelic acid, malonic acid, lactic acid, salicylic acid, propyl gallate, pyrogallol, 8-hydroxyquinoline and cysteine. Preferred chelating agents are aminocarboxylic acids such as EDTA, CyDTA, and aminophosphonic acids such as EDTMP.

[0079] Without being bound by theory, it is believed that the chelating agent, if present, is present in solution in an amount of from about 0.1 wt % to about 10 wt %, preferably from about 0.5 wt % to about 5 wt % of the solution.

[0080] In some embodiments, the solutions of the disclosed and claimed subject matter are free or substantially free of any or all of the above chelating agents added to the compositions.

[0081] Other commonly known components, such as dyes, biocides, and the like, may be included in conventional amounts, for example up to a total amount of about 5% by weight of the solution.

[0082] In some embodiments, the solution may be substantially free or free of one or more of the following: hydroxides, metal hydroxides, such as KOH, LiOH, or NaOH, quaternary ammonium hydroxides, alkanolamines, nitrogen- or sulfur-containing inhibitors, heterocyclic molecules, such as thiazoles, abrasives. In other embodiments, the solution may be substantially free or free of halide-containing compounds other than one or more fluorine-containing compounds, for example, substantially free or free of one or more of the following: bromine, chlorine, or iodine-containing compounds. In other embodiments, the solution may be substantially free or free of sulfonic acid and / or sulfuric acid and / or nitric acid and / or hydrochloric acid. In other embodiments, the solution may be substantially free or free of sulfates and / or nitrates and / or sulfites and / or nitrites. In other embodiments, the solution may be substantially free or free of ammonium hydroxide and / or ethyldiamine. In other embodiments, the solution may be substantially free or free of sodium-containing compounds and / or calcium-containing compounds and / or manganese-containing compounds or magnesium-containing compounds and / or chromium-containing compounds and / or sulfur-containing compounds.

[0083] Other commonly known components, such as dyes, biocides, and the like, may be included in conventional amounts, for example up to a total of about 5% by weight of the solution.

[0084] Typically, the etching solutions of the disclosed and claimed subject matter are prepared by mixing the components together in a container at room temperature until all solids are dissolved in the water-based medium.

[0085] performance As noted above, the etching solutions of the disclosed and claimed subject matter exhibit (i) high etch selectivity for silicon-germanium relative to silicon, and (ii) high etch selectivity for silicon-germanium relative to silicon oxide.

[0086] The etching solutions of the disclosed and claimed subject matter exhibit high etch selectivity for silicon-germanium relative to silicon. In one embodiment, the selectivity is greater than about 50. In one embodiment, the selectivity is greater than about 65. In one embodiment, the selectivity is greater than about 80. In one embodiment, the selectivity is greater than about 100. In one embodiment, the selectivity is greater than about 150. In one embodiment, the selectivity is greater than about 200. In one embodiment, the selectivity is greater than about 250. In one embodiment, the selectivity is greater than about 300. In one embodiment, the selectivity is greater than about 350. In one embodiment, the selectivity is greater than about 400. In one embodiment, the selectivity is greater than about 450. In one embodiment, the selectivity is greater than about 500.

[0087] Additionally, the etching solutions of the disclosed and claimed subject matter exhibit high etch selectivities for silicon-germanium versus silicon oxide. In one embodiment, the selectivity is greater than about 50. In one embodiment, the selectivity is greater than about 65. In one embodiment, the selectivity is greater than about 80. In one embodiment, the selectivity is greater than about 100. In one embodiment, the selectivity is greater than about 150. In one embodiment, the selectivity is greater than about 200. In one embodiment, the selectivity is greater than about 250. In one embodiment, the selectivity is greater than about 300. In one embodiment, the selectivity is greater than about 350. In one embodiment, the selectivity is greater than about 400. In one embodiment, the selectivity is greater than about 450. In one embodiment, the selectivity is greater than about 500.

[0088] method In one other aspect, the disclosed and claimed subject matter provides a method for selectively enhancing the etch rate of silicon-germanium relative to silicon in a microelectronic device that includes silicon and silicon-germanium (a compound semiconductor). The method comprises: (a) contacting a silicon and silicon-germanium containing microelectronic (compound semiconductor) device with an etching solution described herein; (b) rinsing the microelectronic (compound semiconductor) device after at least partial removal of the silicon-germanium; and (c) optionally drying the microelectronic device. Comprises, consists essentially of, or consists of. In a further embodiment, the method includes a drying step (c). By "at least partially removed" is meant at least 50% removal of the material, preferably at least 80% removal. More preferably, 100% removal of silicon-germanium is achieved using the solutions of the disclosed and claimed subject matter.

[0089] The contacting step (a) can be carried out by any suitable technique, such as by immersion, spraying, or single wafer process. The temperature of the solution during the contacting step (a) is preferably about 25° C. to about 100° C., more preferably about 30° C. to about 50° C. The contacting time can be any suitable time, but is generally about 1 minute to about 60 minutes.

[0090] The rinsing step (b) can be carried out in any suitable manner, for example the substrate can be immersed or sprayed with deionized water, in a preferred embodiment the rinsing step can be carried out with a mixture of deionized water and an organic solvent, such as isopropyl alcohol.

[0091] The drying step (c) may be carried out by any suitable technique, such as isopropyl alcohol (IPA) vapor drying, heat or centripetal force.

[0092] When used in the methods, the solutions of the disclosed and claimed subject matter exhibit the above-mentioned etch selectivities.

[0093] The features and advantages are more fully illustrated by the illustrative examples discussed below. EXAMPLES

[0094] example Reference is now made to more specific embodiments of the present disclosure and experimental results which provide support for such embodiments. The examples are provided below to more fully illustrate the disclosed subject matter and are not to be construed as limiting the disclosed subject matter in any way.

[0095] It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed subject matter and specific examples provided herein without departing from the spirit or scope of the disclosed subject matter. Thus, the disclosed subject matter, including the details provided by the following examples, is intended to cover modifications and variations of the disclosed subject matter that are within the scope of any claims and their equivalents.

[0096] Materials and Methods All materials used in this patent application were purchased and / or available from Sigma Aldrich and were used in the formulations as received.

[0097] Etching tests were conducted in 250 mL beakers with a ½ inch circumference Teflon® stirring bar set at 400 rpm. The etching composition was heated on a hot plate to a temperature of about 45° C. The test coupons were immersed in the composition with stirring for about 20 minutes.

[0098] The segments were then rinsed in a DI water bath or spray for 3 minutes, followed by drying using filtered nitrogen. The etch rates (Å / min) of silicon, silicon oxide, and silicon-germanium before and after etching were estimated from the change in thickness and measured by spectroscopic ellipsometry (SCI FilmTek SE2000). Typical starting layer thicknesses were 1000 Å for Si and silicon oxide, and 1000 Å for SiGe.

[0099] General Procedure for Preparing Cleaning Solutions All solutions of interest in this example were prepared by mixing the components in a 250 mL beaker with a 1 inch Teflon® coated stir bar. Typically, the first material added to the beaker was deionized (DI) water, followed by the other components in no particular order. Typically, the oxidizing agent (e.g., hydrogen peroxide) is added immediately prior to use.

[0100] solution Table 3 shows the effect of various Si-containing molecules on the etch rates of SiGe and SiO. In Table 3, Example 1 had high selectivity of SiGe over Si. However, Example 1 had a high etch rate of SiO2, resulting in low selectivity of SiGe over SiO2. The addition of Si-containing molecules such as silicic acid and Si compound 1 significantly decreased the etch rate of SiO2. However, the SiGe etch rate also significantly decreased. The addition of methyltrimethoxysilane especially decreased the etch rate of SiO2, while only slightly decreased the etch rate of SiGe. Table 3 [Table 3]

[0101] When citric acid was used as the multifunctional acid, the addition of methyltrimethoxysilane also decreased the etch rate of SiO2 with little apparent change in the etch rate of SiGe. The etch rate of Si also did not change appreciably and was very low. Table 4 illustrates the use of citric acid as a multifunctional acid for the selectivity of SiGe to SiO2. Table 4 [Table 4]

[0102] Table 5 shows one alternative embodiment of an etching solution in accordance with the disclosed and claimed subject matter. Table 5 [Table 5]

[0103] Table 6 shows the effect of temperature on the use of the formulation of Example 8. As shown, the process temperature had no significant effect on the etch rate of silicon oxide and silicon, while the etch rate of SiGe increased with increasing process temperature, thus increasing the selectivity of SiGe over silicon and silicon oxide. Table 6 [Table 6]

[0104] Table 7 shows the effect of H2O2 concentration for the use of the formulation of Example 8 at 50° C. As shown, H2O2 peroxide concentration had no significant effect on the etch rate of silicon oxide and silicon, while the etch rate of SiGe increased with increasing H2O2 concentration, thus increasing the selectivity of SiGe over silicon and silicon oxide. Table 7 [Table 7]

[0105] Table 8 shows the effect of Ge concentration in the SiGe alloy for the use of the formulation of Example 8. The results show that with increasing Ge concentration in the SiGe alloy, the SiGe etch rate increases obviously, and therefore the selectivity of SiGe to silicon or silicon oxide increases. Table 8 [Table 8]

[0106] Table 9 shows one other embodiment of an etching solution in accordance with the disclosed and claimed subject matter. Table 9 [Table 9]

[0107] conclusion The disclosed and claimed etching solutions use an effective silicon oxide corrosion inhibitor, and therefore can increase the etch rate of SiGe at higher HF concentrations, while the etch rates of silicon and silicon oxide are unaffected. 0.75 Ge 0.25 The compounded formulation was used to demonstrate nanosheet separation using SiGe / Si multilayer stacks with widths over 160 nm with minimal Si loss. Within reasonable processing times, the sacrificial layer (5 nm to 25 nm SiGe) was completely removed with no obvious damage to Si, silicon oxide, and silicon nitride. The compound shows strong selectivity for SiGe over SiO2 due to the very low SiO2 etch rate.

[0108] Although the disclosed and claimed subject matter has been described with a certain degree of specificity, it is understood that the disclosure is for illustrative purposes only, and that many variations in the conditions and sequence of steps may occur to those skilled in the art without departing from the spirit and scope of the disclosed and claimed subject matter. Accordingly, various modifications can be made and equivalents can be substituted for elements thereof without departing from the scope of the disclosed and claimed subject matter. In addition, many modifications can be made to adapt the teachings of the disclosed and claimed subject matter to a particular condition or material without departing from the essential scope of the disclosed and claimed subject matter. In addition, all numerical values ​​specified in the detailed description should be interpreted as if both the exact value and the approximate value were explicitly specified.

Claims

1. 1. An etching solution suitable for selectively removing silicon-germanium relative to silicon from a microelectronic device, comprising: (i) water; (ii) at least one oxidizing agent; (iii) at least one source of fluoride ions; (iv) at least one multifunctional acid; (v) at least one corrosion-inhibiting surfactant; and (vi) 0.1 wt % to 3 wt % of silicic acid or a compound of formula I: 【Chemistry 1】 Formula 1 at least one silane silicon oxide etch inhibitor comprising a silicon-containing compound of the formula: (i) each of R a and R b is —C 3 H 6 —; (ii) each of R 1 , R 2 , R 4 and R 5 is —H; and (iii) m=0-20.

1. An etching solution comprising:

2. The etching solution of claim 1 comprising at least one water-miscible organic solvent.

3. The etching solution of claim 1, comprising 50 wt % to 90 wt % water.

4. 2. The etching solution of claim 1, wherein the oxidizer comprises 1.5 wt % to 20 wt % of one or more of hydrogen peroxide, periodic acid, potassium iodate, potassium permanganate, ammonium persulfate, ammonium molybdate, ferric nitrate, nitric acid, potassium nitrate, ammonia, and mixtures thereof.

5. 10wt% to 20wt% undiluted H 2 O 2 2. The etching solution of claim 1 , comprising:

6. The fluoride ion source is selected from the group consisting of hydrofluoric acid, ammonium fluoride, ammonium difluoride, quaternary ammonium fluorides, fluoroborates, fluoroboric acid, tetrabutylammonium tetrafluoroborate, aluminum hexafluoride, and fluoride salts of the formula: R 1 NR 2 R 3 R 4 F (In the formula, R 1 , R 2 , R 3 and R 4 are H or (C 1 ~C 4 2. The etching solution of claim 1, comprising one or more of the following: a fluoride salt of an aliphatic primary, secondary or tertiary amine having a carbon atom, ...

7. 2. The etching solution of claim 1, wherein the fluoride ion source comprises 0.01 wt % to 8 wt % of one or more of ammonium fluoride, ammonium difluoride, tetramethylammonium fluoride, tetraethylammonium fluoride, methyltriethylammonium fluoride, tetrabutylammonium fluoride, and combinations thereof.

8. 10. The etching solution of claim 1, wherein the source of fluoride ions comprises one or more of ammonium fluoride and ammonium difluoride.

9. 0.04 wt% to 2.5 wt% undiluted NH 4 The etching solution of claim 1 comprising F.

10. 2. The etching solution of claim 1, wherein the at least one multifunctional acid comprises 0.1 wt % to 5 wt % of one or more multifunctional organic acids selected from the group of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, 2-methylpropane-1,2,3-triscarboxylic acid, benzene-1,2,3-tricarboxylic acid, propane-1,2,3-tricarboxylic acid, 1,cis-2,3-propenetricarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentanetetra-1,2,3,4-carboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, benzenepentacarboxylic acid, and benzenehexacarboxylic acid.

11. The etching solution of claim 1, comprising 0.1 wt % to 5 wt % citric acid.

12. 2. The etching solution of claim 1, wherein the at least one multifunctional acid comprises 0.1 wt % to 5 wt % of one or more multifunctional inorganic acids selected from the group of boric acid, carbonic acid, phosphorous acid, phosphorous acid, silicic acid, sulfurous acid, sulfuric acid, phosphoric acid, pyrophosphoric acid, and orthosilicic acid.

13. 0.1 wt% to 5 wt% H 3 P.O. 4 2. The etching solution of claim 1 , comprising:

14. 2. The etching solution of claim 1, wherein the at least one corrosion-inhibiting surfactant comprises 0.01 wt % to 3 wt % of one or more of a polyalkyleneimine, an acetylenic diol, a modified acetylenic diol, a polypropylene glycol, a polyethylene or polypropylene glycol ether, or mixtures thereof.

15. 2. The etching solution of claim 1, wherein the at least one corrosion-inhibiting surfactant comprises one or more of PEG-400, Lupasol® 800, and Surfynol® 485.

16. 2. The etching solution of claim 1, wherein the at least one silane silicon oxide etch inhibitor further comprises one or more of methyltrimethoxysilane, ethyltrimethoxysilane, triethoxy(ethyl)silane, vinyltrimethoxysilane, trimethoxyphenylsilane, triethoxymethylsilane, trimethoxy(octyl)silane, propyltrimethoxysilane, isobutyl(trimethoxy)silane, trimethoxysilane, n-propyltriethoxysilane, trimethoxy(octadecyl)silane, hexadecyltrimethoxysilane, methyl(tripropyl)silane, ethyl(tripropyl)silane, and propyl(tripropyl)silane.

17. 0.1 wt % to 3 wt % of the following formula: 【Chemistry 2】 10. The etching solution of claim 1 comprising a silicon-containing compound having the formula:

18. The etching solution of claim 2, comprising 1 wt % to 50 wt % of the at least one water-miscible solvent selected from the group consisting of ethylene glycol, propylene glycol, butyl diglycol, 1,4-butanediol, tripropylene glycol methyl ether, dipropylene glycol monomethyl ether, propylene glycol propyl ether, diethylene glycol n-butyl ether, hexyloxypropylamine, poly(oxyethylene)diamine, dimethylsulfoxide, tetrahydrofurfuryl alcohol, glycerol, alcohols, sulfoxides, sulfolane, and mixtures thereof.

19. The etching solution of claim 1, comprising 5 wt % to 50 wt % propylene glycol.

20. The etching solution of claim 1, comprising 5 wt % to 50 wt % dipropylene glycol monomethyl ether (DPM).

21. 1. A method for selectively enhancing the etch rate of silicon-germanium relative to silicon in a microelectronic device comprising silicon and silicon-germanium, comprising: (a) contacting a microelectronic (compound semiconductor) device containing silicon and silicon-germanium with one or more etching solutions according to any one of claims 1 to 20; and (b) rinsing said microelectronic (compound semiconductor) device after at least partial removal of the silicon-germanium. wherein the etch selectivity for silicon-germanium relative to silicon is greater than 50.

22. The method of claim 21, further comprising drying the microelectronic device.

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