Silicon nitride etching compositions and methods

Abstract

Compositions and methods for wet etching a surface of a microelectronic device substrate containing a surface comprising silicon nitride, silicon oxide, and polysilicon are provided. The method of the invention involves a passivation step and a silicon nitride etching step, more comprehensively described below. The combination of the two steps has been found to greatly improve the selectivity of silicon nitride etch operations in the presence of polysilicon.

Description

Technical Field

[0001] The present invention relates to compositions and methods for selectively etching silicon nitride in the presence of silicon oxide and polysilicon.

[0002] Priority claim

[0003] This application claims priority to U.S. Provisional Patent No. 63 / 341,801, filed May 13, 2022. The priority file is incorporated herein for all purposes. Background Art

[0004] In the microelectronics industry, there is a continuing need for improved device performance and for reduced device size and reduced device feature size. Reduced feature size offers the dual advantages of increased device feature density and increased device speed.

[0005] Reducing feature and device size requires finding new ways to improve the steps of the multi-step process of manufacturing microelectronic devices. In the methods for preparing various types of microelectronic devices, the step of removing silicon nitride is common. Thin layers of silicon nitride (Si3N4), usually deposited by chemical vapor deposition from silane (SiH4) and ammonia (NH3), can be used in microelectronic devices as a barrier to water and sodium. In addition, patterned silicon nitride layers are used as masks for spatially selective silicon oxide growth. After application, all or part of these silicon nitride materials may need to be removed, which is usually done by etching.

[0006] Removing silicon nitride from the substrate by etching is advantageously performed in a manner that does not damage or destroy other exposed or covered features of the microelectronic device. Typically, a method of removing silicon nitride is performed in a manner that preferentially removes silicon nitride relative to other materials (such as silicon oxide) that are also present at the surface of the microelectronic device substrate. According to various commercial methods, silicon nitride is removed from the surface of the microelectronic device by a wet etching process involving exposing the substrate surface to concentrated phosphoric acid (H3PO4) at high temperatures, such as in a bath having a temperature in the range of 150°C to 180°C. Conventional wet etching techniques for selectively removing silicon nitride relative to silicon oxide have used aqueous phosphoric acid (H3PO4) solutions (typically about 85% by weight phosphoric acid and 15% by weight water). Using fresh hot phosphoric acid, a typical Si3N4:SiO2 selectivity can be about 40:1.

[0007] In other device structures, in addition to silicon oxide, exposed surfaces of polysilicon may be present, further complicating the desired selective silicon nitride etch process.Therefore, there is a need for compositions and methods that can be used to preferentially etch silicon nitride in the presence of silicon oxide and polysilicon surfaces. Summary of the invention

[0008] In general, the present invention relates to compositions and methods for wet etching the surface of a microelectronic device substrate containing a surface comprising silicon nitride, silicon oxide and polysilicon. Optionally, other materials are present on the substrate, such as conductive materials, semiconductor materials, or insulating materials that can be used in microelectronic devices or processing materials that can be used to prepare microelectronic devices. Materials such as metal silicides may also be present, but are generally not exposed except in the case of defects (such as cracks or lithographic misalignment). The method of the present invention involves a passivation step and a silicon nitride etching step, as described more fully below. It was found that the combination of the two steps greatly improves the selectivity of the silicon nitride etching operation in the presence of polysilicon and silicon oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A diagram showing a process flow for a structure having polysilicon at the bottom of a via while also containing silicon oxide and silicon nitride surfaces is presented. The first step of surface oxide removal is typically performed with dilute hydrogen fluoride. Without the passivation step of the present invention, the exposed polysilicon is typically and undesirably etched and roughened during the silicon nitride etch step.

[0010] Figure 2 A graphical representation of the results of the method of the present invention is presented, wherein microelectronic device substrates having polysilicon, silicon oxide, and silicon nitride surfaces are subjected to the process of the present invention with greatly reduced etching and roughening of the exposed polysilicon surface. DETAILED DESCRIPTION

[0011] As used in this specification and the following claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. As used in this specification and the following claims, the term "or" is generally used in its sense including "and / or" unless the context clearly dictates otherwise.

[0012] The term "about" generally refers to a range of values ​​that are considered equivalent to the recited value (eg, having the same function or result). In many cases, the term "about" may include values ​​that are rounded to the nearest significant figure.

[0013] Numerical ranges expressed as endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). In a first aspect, the invention provides a composition comprising the reaction product of:

[0014] a. about 20 to about 80 weight percent sulfuric acid;

[0015] b. about 20 to about 80 wt % water;

[0016] c. about 0.01 to about 0.4 weight percent sulfurous acid;

[0017] d. about 0.1 to about 10 weight percent nitric acid; and optionally

[0018] e. About 0.001 to about 0.1 wt % formic acid.

[0019] In these compositions, the starting material components thus include a. to d., and optionally e., wherein the total weight percent of such components is 100 weight percent. In one embodiment, the composition is the reaction product of:

[0020] a. about 59 to about 65 weight percent sulfuric acid;

[0021] b. about 36 to about 41% by weight water;

[0022] c. about 0.01 to about 0.3 weight percent sulfurous acid;

[0023] d. about 0.1 to about 0.04 weight percent nitric acid; and optionally

[0024] e. About 0.005 to about 0.1 wt % formic acid.

[0025] In another embodiment of this aspect, the nitric acid is used in an amount of about 0.1 to about 0.25 weight % based on the total weight of the composition.

[0026] As mentioned above, the first aspect is a composition which is the reaction product of the starting materials. In solution, the primary oxidant is nitric acid. It is believed that sulfurous acid can reduce some nitric acid to provide more active oxidizing species in situ, such as nitrogen dioxide and nitrous acid.

[0027] In certain embodiments, the composition also uses formic acid, which helps extend the bath life. In the composition of the aspect, the formic acid is most likely partially oxidized to performic acid.

[0028] The composition of the first aspect can be used as a passivation composition in the selective etching of silicon nitride on microelectronic substrates. The composition is found to be effective in passivating surfaces other than silicon nitride, particularly polysilicon and silicon oxide surfaces, which are also typically present on microelectronic device substrates when performing the desired silicon nitride etching step.

[0029] In the selective etching of silicon nitride, the first step generally involves removing any residual surface oxide material on the silicon nitride surface, typically using dilute HF, and then treating the microelectronic device substrate with the composition of the first aspect, followed by rinsing and then treating with the silicon nitride etching composition. Thus, in a second aspect, the present invention provides a method of selectively etching silicon nitride on a microelectronic device substrate, the substrate comprising a surface comprising silicon nitride, a surface comprising silicon oxide, and a surface comprising polysilicon, the method comprising:

[0030] a. exposing a microelectronic device substrate comprising a surface of silicon nitride, silicon oxide, and polysilicon to a composition comprising nitrous acid;

[0031] then

[0032] b. rinsing the substrate with a liquid solution comprising water; and

[0033] c. exposing the substrate to a composition effective to etch silicon nitride under conditions effective to etch silicon nitride.

[0034] In one embodiment, the present invention provides a method for selectively etching silicon nitride on a microelectronic device substrate, the substrate comprising a surface comprising silicon nitride, a surface comprising silicon oxide, and a surface comprising polysilicon, the method comprising:

[0035] a. exposing a microelectronic device substrate comprising a surface of silicon nitride, silicon oxide, and polysilicon to a composition comprising the reaction product of:

[0036] i. about 20 to about 80 weight percent sulfuric acid;

[0037] ii. about 20 to about 80 wt % water;

[0038] iii. about 0.01 to about 0.4 weight percent sulfurous acid;

[0039] iv. about 0.1 to about 10 weight percent nitric acid; and optionally

[0040] v. About 0.001 to about 0.1 weight percent formic acid.

[0041] then

[0042] b. rinsing the substrate with a liquid solution comprising water; and

[0043] c. exposing the substrate to a composition effective to etch silicon nitride under conditions effective to etch silicon nitride.

[0044] In the method, the composition effective for etching silicon nitride (i.e., step c.) includes those compositions known in the related art to be effective for etching silicon nitride, such as a phosphoric acid and water mixture. In the method, it is found that the initial passivation step (a) performed prior to silicon nitride etching greatly enhances the selectivity of silicon nitride etching relative to the polysilicon surface present on the microelectronic device substrate.

[0045] In one embodiment, the composition effective for etching silicon nitride comprises at least 60, at least 70, at least 80, or at least 90 weight percent of the phosphoric acid composition, based on the total weight of the composition.

[0046] In another embodiment, the composition effective for etching silicon nitride further comprises various additives as described below.

[0047] In one embodiment, the composition effective for etching silicon nitride further comprises:

[0048] A composition comprising:

[0049] a. Compounds of the following formula

[0050]

[0051] Where A is an aromatic ring or a heteroaromatic ring, and each R 1 are the same or different and are selected from hydrogen, hydroxyl (hydroxy / hydroxyl), C1-C 20 Alkyl, C1-C 20 Alkylamino, phenyl, benzyl, and C1-C 20 alkoxy, phenoxy, and C3-C8 cycloalkyl; x is 0 or 1; each y and y' may be the same or different and is zero or an integer selected from 1 to 5; z is an integer selected from 1, 2 or 3; m is an integer selected from 1, 2 or 3; w is zero or an integer selected from 1, 2, 3 or 4 and m+z=4; and / or

[0052] b. Compounds of the formula:

[0053] (R 1 )3Si—M—Si(R 1 )3,

[0054] Among them, each R 1 are the same or different and are as defined above, and -M- is selected from -NH- or -O-.

[0055] In one embodiment, the composition effective for etching silicon nitride may further comprise a compound described in U.S. Patent Publication No. 2021 / 0054236, which is incorporated herein by reference. Illustrative compounds include those of the formula

[0056]

[0057] Where X is O or N; R 2 to R 7 Each independently selected from hydrogen, C1-C 20 Alkyl, C1-C 20 Alkoxy, C2-C 20 Alkenyl, C3-C 20 Cycloalkyl, C1-C 20 Aminoalkyl, C6-C 20 Aryl, C1-C 20 Alkylcarbonyl, C1-C 20 Alkylcarbonyloxy, C1-C 10 Cyanoalkyl; z is 0 or 1; and when z is 0, R 2 to R 5 At least two of them are C1-C 20 Alkoxy.

[0058] In certain embodiments, the composition of the present invention may further comprise at least one silane selected from (a) alkylaminoalkoxysilane and (b) alkylaminohydroxysilane, wherein the silane has at least one moiety selected from alkoxy and hydroxy. In one embodiment, the alkylaminoalkoxysilane and alkylaminohydroxysilane compounds are selected from

[0059] N-(3-trimethoxysilylpropyl)diethylenetriamine;

[0060] N-(2-aminoethyl)-3-aminopropyltriethoxysilane;

[0061] N-(2-aminoethyl)-3-aminopropylsilanetriol;

[0062] N 1 -(3-trimethoxysilylpropyl)diethylenetriamine;

[0063] N-(6-aminohexyl)aminopropyltrimethoxysilane;

[0064] (3-aminopropyl)triethoxy-silane; and

[0065] (3-Aminopropyl)silanetriol (APST) and its phosphate esters.

[0066] The above compounds tend to form phosphate esters in concentrated phosphoric acid solutions in equilibrium reactions, so that, in practice, at least a portion of such compounds will be present as phosphate esters.

[0067] As used herein, the term "microelectronic device" (or "microelectronic device substrate" or simply "substrate") is used in a manner consistent with the generally understood meaning of such terms in the electronics, microelectronics, and semiconductor manufacturing arts, such as to refer to any of a number of different types: semiconductor substrates; integrated circuits; solid-state memory devices; hard disks; read, write, and read-write heads and their mechanical or electronic components; flat panel displays; phase change memory devices; solar panels and other products that include one or more solar cell devices; photovoltaic devices; and microelectromechanical systems (MEMS) fabricated for use in microelectronic, integrated circuit, energy harvesting, or computer chip applications. It should be understood that the term "microelectronic device" may refer to any in-process microelectronic device or microelectronic device substrate containing or prepared to contain functional electronic (current carrying) structures, functional semiconductor structures, and insulating structures for final electronic applications in microelectronic devices or microelectronic assemblies.

[0068] As used herein, the term "silicon nitride" is given a meaning consistent with that used in the microelectronics and semiconductor manufacturing industries. Consistent therewith, silicon nitride refers to materials including thin films made of amorphous silicon nitride having commercially useful low levels of other materials or impurities and possibly some variation with respect to the nominal stoichiometry of Si3N4. Silicon nitride may be present as part of a microelectronic device substrate as a functional feature of the device, such as as a barrier layer or insulating layer, or may be present as a material used to facilitate a multi-step manufacturing process for making a microelectronic device.

[0069] As used herein, the term "silicon oxide" is given a meaning consistent with that used in the microelectronics and semiconductor manufacturing industries. Consistent therewith, silicon oxide refers to a material composed of silicon oxide (SiO x ) (e.g. SiO2, "thermal oxide" (ThO x ) etc. The silicon oxide can be placed on the substrate by any method, such as by deposition by chemical vapor deposition from TEOS or another source, or by thermal deposition. The silicon oxide can advantageously contain other materials or impurities at low levels that are commercially useful. The silicon oxide can be present as part of a microelectronic device substrate as a feature of the microelectronic device, for example as an insulating layer.

[0070] As used herein, "polycrystalline silicon" or polycrystalline Si or poly-Si is understood by those skilled in the art to be a polycrystalline form of silicon composed of multiple small silicon crystals. It is typically deposited using low pressure chemical vapor deposition (LPCVD) and is typically doped n-type polycrystalline silicon or p-type polycrystalline silicon. The degree of doping can range from lightly doped (e.g., at 10 13 cm -3 to 10 18 cm -3range) to heavily doped (e.g. greater than 10 18 cm -3 ) as will be readily appreciated by those skilled in the art. Examples of p-doped materials include polysilicon doped with a dopant species from Group IIIA of the periodic table (e.g., boron, aluminum, gallium, and / or indium). The n-doped material may, for example, be polysilicon doped with a dopant species from Group IV (silicon, germanium, or tin) or Group V (phosphorus, arsenic, antimony, or bismuth) of the periodic table.

[0071] Certain embodiments of etching compositions include compositions in the form of an aqueous solution comprising, consisting essentially of, or consisting of aqueous phosphoric acid (e.g., concentrated phosphoric acid and optionally an amount of added water) together with one or more of the above compounds in an amount effective to improve the etch rate of silicon nitride or the selectivity of silicon nitride to polysilicon; and optionally a fluoride compound in an amount effective to produce the desired etch (including a useful or advantageous etch rate) of silicon nitride and / or optionally dissolved silicon dioxide.

[0072] These and other example compositions may comprise, consist of, or consist essentially of the listed ingredients and optional ingredients. Throughout the present description, as a general convention, a composition of matter (such as a described etching composition, or an ingredient or component thereof) referred to as "consisting essentially of" a specified group of ingredients or materials refers to a composition containing the specified ingredients or materials and no more than a low or insignificant amount of other ingredients or materials, for example, no more than 5, 2, 1, 0.5, 0.1 or 0.05 parts by weight of the other ingredients or materials.

[0073] The etching composition comprises an amount of aqueous phosphoric acid (e.g., concentrated phosphoric acid) effective to produce the desired etching of silicon nitride. The term "aqueous phosphoric acid" refers to a component of the etching composition that is mixed or combined with other components of the etching composition to form the etching composition. The term "phosphoric acid solids" refers to an aqueous phosphoric acid component or a non-aqueous component of an etching composition prepared from an aqueous phosphoric acid component.

[0074] The amount of phosphoric acid solids contained in the etching composition can be an amount that will provide the desired etching performance (including the desired silicon nitride etching rate and selectivity, which generally requires a relatively high amount (concentration) of phosphoric acid solids) in combination with the other materials of the etching composition. As described above, phosphoric acid will be present in a proportion of at least 60, at least 70, at least 80, or at least 90 weight percent of the total weight of the composition of phosphoric acid. In certain embodiments, the phosphoric acid content will be between about 80 and 90 weight percent.

[0075] To provide a desired amount of phosphoric acid solids, the composition may contain "concentrated" phosphoric acid as a component, which is mixed or combined with other components (one component is optionally water, in a certain form) to produce an etching composition. "Concentrated" phosphoric acid refers to an aqueous phosphoric acid component, which contains a high amount or maximum amount of phosphoric acid solids and substantially no other components (e.g., any non-aqueous or non-phosphoric acid solid material less than 0.5 or 0.1 weight percent) in the presence of a low amount or minimum amount of water. Concentrated phosphoric acid can generally be considered to have at least about 80 or 85 weight percent phosphoric acid solids contained in about 15 or 20 weight percent water. Alternatively, the etching composition can be considered to include a certain amount of concentrated phosphoric acid diluted with water, meaning, for example, concentrated phosphoric acid that has been diluted with a certain amount of water before or after being combined with other components of the etching composition or equivalents formed in any manner. As another alternative, the component of the etching composition can be concentrated phosphoric acid or dilute phosphoric acid, and the etching composition can contain an additional amount of water, which is provided to the etching composition as a component of a different component or as a separate water component.

[0076] As used herein, the term "fluoride compound" refers to certain etchants that are optionally added to increase the etching rate of silicon nitride. Such compounds include, but are not limited to, HF, ammonium fluoride, tetrafluoroboric acid, hexafluorosilicic acid, other compounds containing B-F or Si-F bonds, tetrabutylammonium tetrafluoroborate (TBA-BF4), tetraalkylammonium fluorides, and combinations thereof. In one embodiment, the fluoride compound is selected from HF, ammonium fluoride, tetrafluoroboric acid, hexafluorosilicic acid, tetrabutylammonium tetrafluoroborate, tetra(C1-C6 alkyl)ammonium fluoride, and combinations thereof.

[0077] The amount of the optional fluoride compound contained in the composition of the present invention can be an amount that will provide the desired etching performance (including the desired silicon nitride etching rate and selectivity) in combination with other materials of the etching composition. For example, the etching composition may contain about 5 to 10,000 or even up to 50,000 parts / million (i.e., 0.0005 to 1 or even 5 weight percent) based on the total weight of the etching composition, such as about 20 to 2,000 parts / million (i.e., 0.002 to 0.2 weight percent) based on the total weight of the etching composition. In certain embodiments, the composition does not contain or is substantially free of such fluoride compounds. "Substantially free" is defined as less than 2 weight percent, less than 1 weight percent, less than 0.5 weight percent or less than 0.1 weight percent as used herein in certain embodiments. "Free" is intended to correspond to less than 0.001 weight percent as used herein in certain embodiments to explain environmental pollution and corresponds to 0.0 weight percent in another embodiment.

[0078] Optionally, the composition of the present invention may further comprise an amount of silicon dioxide dissolved in phosphoric acid ("added silicon dioxide"), for example, by dissolving a solid silicon dioxide material in phosphoric acid or by adding a soluble silicon-containing compound that can form dissolved silicon dioxide by reaction with aqueous phosphoric acid, examples of such compounds include (a) TMAS (tetramethylammonium silicate), (b) tetraacetoxysilane, or (c) tetraalkoxysilanes, such as tetramethoxysilane, tetraethoxysilane, etc. Dissolved silicon dioxide can be effective in improving the selectivity of the etching composition to silicon nitride. The amount can be any useful amount that does not result in supersaturation of the pre-treated silicon dioxide under the conditions of the etching process, such as about 5 to 10,000 parts per million of dissolved silicon dioxide or soluble silicon-containing compound based on the total weight of the etching composition or about 20 to 5,000, 3,000, 1,000 or 500 parts per million based on the total weight of the etching composition. As with the other additives described above, such compounds tend to form phosphate esters in concentrated phosphoric acid solution in an equilibrium reaction and therefore, in practice, at least a portion will be present as the phosphate ester.

[0079] The etching composition may contain water from a source or from multiple sources. For example, water will be present in an aqueous phosphoric acid composition. In addition, water can be used as a carrier for one or more of the other components of the composition, and water can be added separately as its own component. The amount of water should be sufficiently low to allow the composition to exhibit desired or preferred or advantageous performance properties, including useful (sufficiently high) silicon nitride etching rates. The increase in the presence of water tends to increase the etching rate of silicon nitride but can also reduce the boiling point of the composition, which forces the reduction and opposite effects of the operating temperature of the composition. The example of the amount of water from all sources in the etching composition can be less than about 50, 40 or 30 weight percent, such as in the range of about 5 weight percent to about 25 weight percent based on the gross weight of the etching composition, or in the range of about 10 to 20 weight percent water based on the gross weight of the etching composition.

[0080] In certain embodiments, the compositions of the present invention do not require and may exclude other types of ingredients that are not typically included in etching compositions, such as pH adjusters and solid materials (eg, abrasives).

[0081] The compositions of the present invention may be prepared by any method useful for producing etching compositions as described. By one method, the aqueous or solid ingredients may be combined, optionally with the application of heat, and mixed to homogeneity.

[0082] As described above, the composition as described can be used in a method of removing silicon nitride from the surface of a microelectronic device substrate. The substrate can contain other materials that can be used in a microelectronic device, such as an insulator, a barrier layer, a conductive material, a semiconductor material, or one or more of materials that can be used to process the microelectronic device (e.g., photoresist, mask, etc.). Example substrates have surfaces including silicon nitride, thermal oxide (ThOx), and PETEOS (oxide deposited using plasma enhanced tetraethylorthosilicate) and polysilicon.

[0083] In use, the compositions of the present invention can provide useful etching properties in accordance with commercial performance requirements and desires, and can provide improved performance with respect to etch rate and selectivity of silicon nitride relative to polysilicon as compared to comparative etching compositions.

[0084] The silicon nitride etching operation is effective to at least partially remove silicon nitride on the surface of the microelectronic device substrate. The phrase "at least partially remove" corresponds to removal of at least about 85%, at least 90%, at least 95%, or at least about 99% of the silicon nitride present on the device prior to particle removal.

[0085] The method can be performed on known and commercially available equipment. Generally, to etch a substrate to selectively remove material from the surface of the substrate, an etching composition can be applied to the surface and allowed to contact surface structures to chemically selectively remove certain structures.

[0086] Silicon nitride films occasionally have a thin oxide surface that can inhibit the etching process because the composition is designed to etch oxide very slowly. In such cases, a very brief treatment with dilute HF can be an advantageous first process step.

[0087] In an etching step, the composition can be applied to the surface in any suitable manner, such as by spraying the composition onto the surface; by dipping the substrate (in a static or dynamic volume of the composition) into the etching composition; by contacting the surface with another material having the etching composition absorbed thereon (e.g., a pad or fibrous sorbent applicator assembly); by contacting the substrate with a volume of the etching composition in a circulating bath; or by any other suitable means, manner, or technique for bringing the etching composition into removal contact with the surface of a microelectronic substrate containing silicon-germanium and silicon. The application can be in batch or single wafer equipment for dynamic or static cleaning.

[0088] The conditions (e.g., time and temperature) of a useful etching process may be any conditions found to be effective or advantageous. In general, the etching composition is contacted with the surface, such as by immersing in an etching composition bath for a period of time sufficient to selectively remove silicon nitride. The time of exposure to the etching composition and the temperature of the etching composition can effectively remove the desired amount of silicon nitride from the surface of the substrate. The time of the etching step should not be too short, because this means that the etching rate of silicon nitride may be too high, which may lead to difficult process control and reduced quality of the microelectronic device at the end of the etching step. Of course, the time required for the etching step is preferably not too long to allow good efficiency and throughput of the etching process and semiconductor manufacturing line. At a temperature in the range of about 100° C. to about 180° C., an example of a useful time for the etching step may be in the range of about 5 minutes to about 300 minutes or about 10 minutes to about 60 minutes. This contact time and temperature are exemplary, and any other suitable time and temperature conditions effective in achieving the desired removal selectivity may be adopted.

[0089] The etching step of the present invention can be used to etch silicon nitride material from the surface of any type of substrate. According to a specific embodiment, the substrate may include alternating thin film layers of silicon nitride as structural features of the substrate, which include alternating thin film layers of silicon nitride layers with silicon oxide and polysilicon, conductive metal silicide and dielectric (such as zirconium oxide or aluminum oxide). The substrate before the etching step includes alternating layers of silicon nitride located in the openings between high aspect ratio silicon oxide structures. The example etching process can exhibit good silicon nitride etching rate, good selectivity relative to silicon oxide of greater than about 150 and at least about 2000 or at least about 4000 in some embodiments.

[0090] After the selective etching of the desired amount of silicon nitride is completed, the etching composition remaining on the surface of the etched microelectronic device can be removed from the surface by any desired and useful method, such as by rinsing, washing or other removal steps, using water (or optionally phosphoric acid followed by water). For example, after etching, the microelectronic device substrate can be rinsed using a rinse of deionized water (e.g., at a temperature in the range of about 20° C. to about 90° C.), followed by drying, such as spin drying, N2, steam drying, etc. After rinsing, the substrate surface can be assayed for the presence and amount of particles at the surface.

[0091] The compositions described herein can be easily formulated by simply adding the individual components and mixing to a uniform condition. In addition, the compositions can be easily formulated as single-package formulations or multi-part formulations that are mixed when or before use, preferably multi-part formulations. The individual parts of the multi-part formulation can be mixed at the tool or in a mixing area (region / area) (such as an in-line mixer) or in a storage tank upstream of the tool. It is contemplated that the individual parts of the multi-part formulation may contain any combination of components / ingredients that form the desired composition when mixed together. The concentration of the individual components can vary widely with a specific multiple of the semi-aqueous composition (i.e., more diluted or more concentrated), and it should be understood that the semi-aqueous composition may variously and alternatively contain, consist of, or consist essentially of any combination of components consistent with the disclosure herein. Therefore, in a third aspect, the present invention provides a kit comprising two or more of the following in two or more containers

[0092] i. a passivation composition as in the first aspect,

[0093] ii. Phosphoric acid,

[0094] iii. water; and

[0095] iv. One or more compounds selected from the following

[0096] Tetramethylammonium silicate (TMAS)

[0097] N-(3-trimethoxysilylpropyl)diethylenetriamine;

[0098] N-(2-aminoethyl)-3-aminopropyltriethoxysilane;

[0099] N-(2-aminoethyl)-3-aminopropylsilanetriol;

[0100] N 1 -(3-trimethoxysilylpropyl)diethylenetriamine;

[0101] N-(6-aminohexyl)aminopropyltrimethoxysilane;

[0102] (3-aminopropyl)triethoxy-silane; and

[0103] (3-Aminopropyl)silanetriol (APST) and its phosphate esters.

[0104] The container of the kit must be suitable for storing and transporting the semi-aqueous composition components, e.g. Containers (Entegris, Inc.). The one or more containers containing the components of the composition preferably include means for placing the components in fluid communication in the one or more containers for admixture and dispensing. For example, reference The system can be configured to provide a container, gas pressure can be applied to the exterior of the liner in the one or more containers to cause at least a portion of the contents of the liner to be expelled and thereby initiate fluid communication for blending and dispensing. Alternatively, gas pressure can be applied to the head space of a conventional pressurizable container or a pump can be used to initiate fluid communication. In addition, the system preferably includes a dispensing port for dispensing the blended composition to a processing tool.

[0105] The liner of the one or more containers can be made using a substantially chemically inert, impurity-free, flexible and elastic polymer film material (such as high density polyethylene). It is expected that the liner material is generally processed without the need for coextrusion or barrier layers and without any pigment, UV inhibitor or processing agent that can adversely affect the purity requirements of the components to be configured in the liner. The list of expected liner materials includes films comprising pure (additive-free) polyethylene, pure polytetrafluoroethylene (PTFE), polypropylene, polyurethane, polyvinylidene chloride, polyvinyl chloride, polyacetal, polystyrene, polyacrylonitrile, polybutylene, etc. The preferred thickness of such liner materials is in the range of about 5 mils (0.005 inches) to about 30 mils (0.030 inches), such as, for example, a thickness of 20 mils (0.020 inches).

[0106] With respect to containers for use in the kits, the disclosures of the following patents and patent applications are incorporated herein by reference in their respective entireties: U.S. Patent No. 7,188,644, entitled "APPARATUS AND METHOD FOR MINIMIZING THE GENERATION OF PARTICLES IN ULTRAPURE LIQUIDS"; and U.S. Patent No. 6,698,619, entitled "RETURNABLE AND REUSABLE, BAG-IN-DRUM FLUIDSTORAGE AND DISPENSING CONTAINER SYSTEM."

[0107] In the following examples, blanket film samples of polysilicon have had their native oxide removed by exposure to 0.5 wt % HF in water at room temperature for 60 seconds. After the HF exposure, the film was rinsed in deionized water and exposed to a passivation treatment. After the passivation treatment, the sample was then rinsed in deionized water and dried with nitrogen. The polysilicon thickness was then measured using spectroscopic ellipsometry. The sample was then exposed to a selective nitride etch formulation at 160C for 2 hours, rinsed, dried and the polysilicon thickness was re-measured again. The etch rates in the table were calculated from the polysilicon thickness change and the selective nitride formulation exposure time.

[0108] Examples –

[0109]

[0110]

[0111] Composition B (silicon nitride etching composition) is phosphoric acid, water, APST and TMAS as follows:

[0112] Components Concentration (weight percent) Phosphoric acid 81.70 water 14.05 APST 4.19 TMAS 0.06 <![CDATA[HNO3]]> 0.25

[0113] Composition A is as follows:

[0114] Components Concentration (weight percent) <![CDATA[H2SO4]]> 61.39 59 to 65 Deionized water 38.14 36 to 41 <![CDATA[H2SO3]]> 0.2 0.01 to 0.3 Formic acid 0.02 0.005 to 0.04 <![CDATA[HNO3]]> 0.25 0.1 to 0.4

[0115] The data show that while several oxidation formulations effectively passivate the annealed n + polysilicon, but only composition A was effective in substantially reducing the annealed n + Etching of polysilicon.

[0116] aspect

[0117] In a first aspect, the present invention provides a composition comprising the reaction product of:

[0118] a. about 20 to about 80 weight percent sulfuric acid;

[0119] b. about 20 to about 80 wt % water;

[0120] c. about 0.01 to about 0.4 weight percent sulfurous acid;

[0121] d. about 0.1 to about 10 weight percent nitric acid; and optionally

[0122] e. About 0.001 to about 0.1 wt % formic acid.

[0123] In a second aspect, the present invention provides a composition which is the reaction product of:

[0124] a. about 59 to about 65 weight percent sulfuric acid;

[0125] b. about 36 to about 41% by weight water;

[0126] c. about 0.01 to about 0.3 weight percent sulfurous acid;

[0127] d. about 0.1 to about 0.04 weight percent nitric acid; and optionally

[0128] e. About 0.005 to about 0.1 wt % formic acid.

[0129] In a third aspect, the present invention provides the composition of the first aspect, wherein the nitric acid is used in an amount of about 0.1 to about 0.25 weight % based on the total weight of the composition.

[0130] In a fourth aspect, the present invention provides a method of selectively etching silicon nitride on a microelectronic device substrate, the substrate comprising a surface comprising silicon nitride, a surface comprising silicon oxide, and a surface comprising polysilicon, the method comprising:

[0131] a. exposing a microelectronic device substrate comprising a surface of silicon nitride, silicon oxide, and polysilicon to a composition comprising nitrous acid;

[0132] then

[0133] b. rinsing the substrate with a liquid solution comprising water; and

[0134] c. exposing the substrate to a composition effective to etch silicon nitride under conditions effective to etch silicon nitride.

[0135] In a fifth aspect, the present invention provides a method of selectively etching silicon nitride on a microelectronic device substrate, the substrate comprising a surface comprising silicon nitride, a surface comprising silicon oxide, and a surface comprising polysilicon, the method comprising:

[0136] a. exposing a microelectronic device substrate comprising a surface of silicon nitride, silicon oxide, and polysilicon to a composition comprising the reaction product of:

[0137] i. about 20 to about 80 weight percent sulfuric acid;

[0138] ii. about 20 to about 80 wt % water;

[0139] iii. about 0.01 to about 0.4 weight percent sulfurous acid;

[0140] iv. about 0.1 to about 10 weight percent nitric acid; and optionally

[0141] v. about 0.001 to about 0.1 weight percent formic acid;

[0142] then

[0143] b. rinsing the substrate with a liquid solution comprising water; and

[0144] c. exposing the substrate to a composition effective to etch silicon nitride under conditions effective to etch silicon nitride.

[0145] In a sixth aspect, the present invention provides the method of the fourth or fifth aspect, wherein the composition effective for etching silicon nitride comprises:

[0146] a. phosphoric acid; and

[0147] b. Liquids containing water.

[0148] In a seventh aspect, the present invention provides the method of the sixth aspect, wherein the phosphoric acid is present in an amount of about 80 to about 90 weight percent based on the total weight of the composition.

[0149] In an eighth aspect, the present invention provides the method of the sixth aspect, wherein the composition effective for etching silicon nitride further comprises:

[0150] A composition comprising:

[0151] a. Compounds of the following formula

[0152]

[0153] Where A is an aromatic ring or a heteroaromatic ring, and each R 1 are the same or different and are selected from hydrogen, hydroxyl (hydroxy / hydroxyl), C1-C 20 Alkyl, C1-C 20 Alkylamino, phenyl, benzyl, and C1-C 20 alkoxy, phenoxy, and C3-C8 cycloalkyl; x is 0 or 1; each y and y' may be the same or different and is zero or an integer selected from 1 to 5; z is an integer selected from 1, 2 or 3; m is an integer selected from 1, 2 or 3; w is zero or an integer selected from 1, 2, 3 or 4 and m+z=4; and / or

[0154] b. Compounds of the formula:

[0155] (R 1 )3Si—M—Si(R 1 )3,

[0156] Among them, each R 1 are the same or different and are as defined above, and -M- is selected from -NH- or -O-.

[0157] In a ninth aspect, the present invention provides the method of the sixth aspect, wherein the composition effective for etching silicon nitride further comprises:

[0158] The following compound

[0159]

[0160] Where X is O or N; R 2 to R 7 Each independently selected from hydrogen, C1-C 20 Alkyl, C1-C 20 Alkoxy, C2-C 20 Alkenyl, C3-C 20 Cycloalkyl, C1-C 20 Aminoalkyl, C6-C 20 Aryl, C1-C 20 Alkylcarbonyl, C1-C 20 Alkylcarbonyloxy, C1-C 10 Cyanoalkyl; z is 0 or 1; and when z is 0, R 2 to R 5 At least two of them are C1-C 20 Alkoxy.

[0161] In a tenth aspect, the present invention provides the method of the fourth or fifth aspect, wherein the composition effective for etching silicon nitride further comprises one or more compounds selected from the group consisting of

[0162] Tetramethylammonium silicate;

[0163] N-(3-trimethoxysilylpropyl)diethylenetriamine;

[0164] N-(2-aminoethyl)-3-aminopropyltriethoxysilane;

[0165] N-(2-aminoethyl)-3-aminopropylsilanetriol;

[0166] N 1 -(3-trimethoxysilylpropyl)diethylenetriamine;

[0167] N-(6-aminohexyl)aminopropyltrimethoxysilane;

[0168] (3-aminopropyl)triethoxy-silane; and

[0169] (3-Aminopropyl)silanetriol, and its phosphate esters.

[0170] In an eleventh aspect, the present invention provides the method of the fourth or fifth aspect, wherein the composition effective for etching silicon nitride comprises about 80 to about 90 weight percent phosphoric acid, water, tetramethylammonium silicate and (3-aminopropyl)silanetriol, the total weight percent being equal to 100%.

[0171] In a twelfth aspect, the present invention provides the method of the eleventh aspect, wherein the composition effective for etching silicon nitride further comprises a fluoride compound.

[0172] In a thirteenth aspect, the present invention provides a kit comprising two or more of the following in two or more containers:

[0173] i. The composition of technical solution 1,

[0174] ii. Phosphoric acid,

[0175] iii. water; and

[0176] iv. One or more compounds selected from the following

[0177] Tetramethylammonium silicate;

[0178] N-(3-trimethoxysilylpropyl)diethylenetriamine;

[0179] N-(2-aminoethyl)-3-aminopropyltriethoxysilane;

[0180] N-(2-aminoethyl)-3-aminopropylsilanetriol;

[0181] N 1 -(3-trimethoxysilylpropyl)diethylenetriamine;

[0182] N-(6-aminohexyl)aminopropyltrimethoxysilane;

[0183] (3-aminopropyl)triethoxy-silane; and

[0184] (3-Aminopropyl)silanetriol, and its phosphate esters.

[0185] Having thus described several exemplary embodiments of the disclosure, it will be readily apparent to those skilled in the art that still other embodiments may be made and used within the scope of the claims appended hereto. The many advantages of the disclosure encompassed by this dossier have been set forth in the foregoing description. However, it should be understood that the disclosure is in many respects merely exemplary. The scope of the invention is of course defined by the language in which the appended claims are expressed.

Claims

1. A composition comprising the reaction product of: a. about 20 to about 80 weight percent sulfuric acid; b. about 20 to about 80 wt % water; c. about 0.01 to about 0.4 weight percent sulfurous acid; d. about 0.1 to about 10 weight percent nitric acid; and optionally e. About 0.001 to about 0.1 wt % formic acid.

2. The composition according to claim 1, which is the reaction product of: a. about 59 to about 65 weight percent sulfuric acid; b. about 36 to about 41% by weight water; c. about 0.01 to about 0.3 weight percent sulfurous acid; d. about 0.1 to about 0.04 weight percent nitric acid; and optionally e. About 0.005 to about 0.1 wt % formic acid.

3. The composition of claim 1, wherein the nitric acid is used in an amount of about 0.1 to about 0.25 weight % based on the total weight of the composition.

4. A method for selectively etching silicon nitride on a microelectronic device substrate, the substrate comprising a surface comprising silicon nitride, a surface comprising silicon oxide, and a surface comprising polysilicon, the method comprising: a. exposing a microelectronic device substrate comprising a surface of silicon nitride, silicon oxide, and polysilicon to a composition comprising nitrous acid; then b. rinsing the substrate with a liquid solution comprising water; and c. exposing the substrate to a composition effective to etch silicon nitride under conditions effective to etch silicon nitride.

5. A method for selectively etching silicon nitride on a microelectronic device substrate, the substrate comprising a surface comprising silicon nitride, a surface comprising silicon oxide, and a surface comprising polysilicon, the method comprising: a. exposing a microelectronic device substrate comprising a surface of silicon nitride, silicon oxide, and polysilicon to a composition comprising the reaction product of: vi. about 20 to about 80 weight percent sulfuric acid; vii. about 20 to about 80 wt % water; viii. about 0.01 to about 0.4 weight percent sulfurous acid; ix. about 0.1 to about 10 weight percent nitric acid; and optionally x. about 0.001 to about 0.1 weight percent formic acid; then b. rinsing the substrate with a liquid solution comprising water; and c. exposing the substrate to a composition effective to etch silicon nitride under conditions effective to etch silicon nitride.

6. The method of claim 5, wherein the composition effective for etching silicon nitride comprises: a. phosphoric acid; and b. Liquids containing water.

7. The method of claim 6, wherein the phosphoric acid is present in an amount of about 80 to about 90 weight percent based on the total weight of the composition.

8. The method of claim 6, wherein the composition effective for etching silicon nitride further comprises: A composition comprising: b. Compounds of the following formula Where A is an aromatic ring or a heteroaromatic ring, and each R 1 are the same or different and are selected from hydrogen, hydroxyl (hydroxy / hydroxyl), C1-C 20 Alkyl, C1-C 20 Alkylamino, phenyl, benzyl, and C1-C 20 alkoxy, phenoxy, and C3-C8 cycloalkyl; x is 0 or 1; each y and y' may be the same or different and is zero or an integer selected from 1 to 5; z is an integer selected from 1, 2 or 3; m is an integer selected from 1, 2 or 3; w is zero or an integer selected from 1, 2, 3 or 4 and m+z=4; and / or c. Compounds of the formula: (R 1 )3Si—M—Si(R 1 )3, Among them, each R 1 are the same or different and are as defined above, and -M- is selected from -NH- or -O-.

9. The method of claim 6, wherein the composition effective for etching silicon nitride further comprises: The following compound Where X is O or N; R 2 to R 7 Each independently selected from hydrogen, C1-C 20 Alkyl, C1-C 20 Alkoxy, C2-C 20 Alkenyl, C3-C 20 Cycloalkyl, C1-C 20 Aminoalkyl, C6-C 20 Aryl, C1-C 20 Alkylcarbonyl, C1-C 20 Alkylcarbonyloxy, C1-C 10 Cyanoalkyl; z is 0 or 1; and when z is 0, R 2 to R 5 At least two of them are C1-C 20 Alkoxy.

10. The method of claim 6, wherein the composition effective for etching silicon nitride further comprises one or more compounds selected from the group consisting of Tetramethylammonium silicate; N-(3-trimethoxysilylpropyl)diethylenetriamine; N-(2-aminoethyl)-3-aminopropyltriethoxysilane; N-(2-aminoethyl)-3-aminopropylsilanetriol; N 1 -(3-trimethoxysilylpropyl)diethylenetriamine; N-(6-aminohexyl)aminopropyltrimethoxysilane; (3-aminopropyl)triethoxy-silane; and (3-Aminopropyl)silanetriol, and its phosphate esters.

11. The method of claim 4, wherein the composition effective for etching silicon nitride comprises about 80 to about 90 weight percent phosphoric acid, water, tetramethylammonium silicate, and (3-aminopropyl)silanetriol, the total weight percent equaling 100 percent.

12. The method of claim 11, wherein the composition effective for etching silicon nitride further comprises a fluoride compound.

13. A kit comprising two or more of the following in two or more containers i. The composition according to claim 1, ii. Phosphoric acid, iii. water; and Iv. One or more compounds selected from the following Tetramethylammonium silicate; N-(3-trimethoxysilylpropyl)diethylenetriamine; N-(2-aminoethyl)-3-aminopropyltriethoxysilane; N-(2-aminoethyl)-3-aminopropylsilanetriol; N 1 -(3-trimethoxysilylpropyl)diethylenetriamine; N-(6-aminohexyl)aminopropyltrimethoxysilane; (3-aminopropyl)triethoxy-silane; and (3-Aminopropyl)silanetriol, and its phosphate esters.

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