Selective removal of metal oxide hardmasks

Abstract

Compositions useful for selective etching (i.e., removal of metal oxide hardmasks, such as zirconium oxide and hafnium oxide, which are frequently used as hardmasks in microelectronic devices, in the presence of other materials, such as polysilicon, silicon dioxide, silicon nitride, and tungsten) are provided.

Description

[Technical field]

[0001] The present invention generally relates to the removal or etching of certain high-k (dielectric constant) dielectric materials, including metal oxide hardmasks such as zirconium oxide and hafnium oxide. [Background technology]

[0002] A conventional semiconductor device may include many metal-oxide-semiconductor field effect transistors ("MOSFETs"), each including at least a source, drain, and gate region. Complementary metal-oxide-semiconductor ("CMOS") uses a complementary and symmetric pair of p-type and n-type MOSFETs, allowing for a higher density of logic functions on a chip.

[0003] The gate region of a MOS or CMOS transistor is generally made of a gate material (e.g., polysilicon) that is disposed on or above an oxide insulator / dielectric (e.g., SiO2) that is in turn deposited on top of a semiconductor material, this combination being commonly referred to as a "gate stack." Despite the reference to "metal" in metal gates and metal oxide semiconductors, polysilicon is the most common gate material in conventional gate fabrication. Polysilicon is the preferred material in the fabrication of gate electrodes due to the ease with which it can be deposited, its resistance to very high (>900°C->1000°C) temperatures in subsequent fabrication steps (e.g., annealing), and its ability to form self-aligned gates. Many of the problems that plague gate fabrication using metals are avoided with polysilicon.

[0004] The gate dielectric of choice in the prior art has long been silicon dioxide. As transistors shrink in size, the thickness of the silicon dioxide dielectric has also been scaled down to improve gate capacitance, thereby increasing current and device performance. The reduction in silicon dioxide gate thickness to less than about 2 nm results in dramatically increased leakage current due to tunneling, causing unwieldy power consumption and poor device reliability. The solution has been to replace the silicon dioxide gate dielectric with a high-k dielectric material such as zirconium oxide, which allows increased gate capacitance without leakage effects.

[0005] In addition, the use of high aspect ratio silicon trenches creates the challenge of selective etching of the zirconium oxide layer or "hard mask" in the presence of silicon dioxide and other materials.

[0006] It is known that high-k dielectrics such as zirconium oxide can be removed using acids, oxidizers, and fluorine compounds such as hydrofluoric acid, fluorosulfuric acid, ammonium fluoride, or ammonium bifluoride (e.g., U.S. Pat. No. 6,656,852). However, such compositions tend not only to etch high-k dielectrics such as zirconium oxide, but also to etch or decompose other materials that may be present, such as polysilicon, silicon dioxide, silicon nitride, and tungsten.

[0007] As a result, a need remains for improved methods for etching high-k dielectric materials, such as zirconium oxide, in the presence of other materials, such as polysilicon, silicon dioxide, silicon nitride, and tungsten. Summary of the Invention

[0008] In summary, the present disclosure provides compositions that are expected to be useful for selective etching (i.e., removal of metal oxide hardmasks such as zirconium oxide and hafnium oxide, which are frequently used as hardmasks in microelectronic devices, in the presence of other materials such as polysilicon, silicon dioxide, silicon nitride, and tungsten). In this regard, certain fluorine compounds are described as etchants in compositions within a given pH range for facilitating the selective removal of zirconium oxide in the presence of other materials. The compositions include: A. Water; b. a fluorine compound selected from ammonium fluoride, ammonium hydrogen difluoride, and hexafluorosilicic acid; c. one or more acids; d. One or more corrosion inhibitors; e. a water soluble component selected from alcohols, glycols, glycol ethers, ammonium halides, and amines; and has a pH of about -2 to 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless expressly stated otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense, including "and / or," unless expressly stated otherwise.

[0010] The term "about" generally refers to a range of numbers that are believed to correspond to a stated value (e.g., have the same function or result). In many cases, the term "about" may include numbers that are rounded to the nearest significant figure.

[0011] Numerical ranges expressed using endpoints include all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0012] In a first aspect, the present invention provides a method for producing a composition comprising the steps of: A. Water; b. a fluorine compound selected from ammonium fluoride, ammonium hydrogen difluoride, and hexafluorosilicic acid; c. one or more acids; d. One or more corrosion inhibitors; and e. a water soluble component selected from alcohols, glycols, glycol ethers, ammonium halides, and amines; and having a pH of about -2 to about 6. In certain embodiments, the pH of the composition is about 0 to about 4, and in other embodiments, about 1 to about 2.

[0013] In one embodiment, the fluorine compound is hexafluorosilicic acid.

[0014] In one embodiment, the acid of component (c) may be selected from hydrochloric acid, nitric acid, propionic acid, citric acid, tartaric acid, and sulfuric acid, and is utilized in such amounts, along with the other components of the composition, to provide the desired pH.

[0015] In one embodiment, the alcohol is methanol, ethanol, isopropanol, butanol, tetrahydrofurfuryl alcohol (THFA), halogenated alcohols (3-chloro-1,2-propanediol, 3-chloro-1- propanethiol, 1-chloro-2-propanol, 2-chloro-1-propanol, 3-chloro-1-propanol, 3-bromo-1,2-propanediol, 1-bromo-2-propanol, 3-bromo-1-propanol, 3-iodo-1-propanol, 4-chloro-1-butanol, and 2-chloroethanol.

[0016] In one embodiment, the alcohol is a C1-C4 alkanol and is selected from methanol, ethanol, propanol, n-butanol, isopropanol, sec-butanol, and t-butyl alcohol ethanol, In one embodiment, the alcohol is ethanol.

[0017] In one embodiment, the glycol is selected from C2-C4 diols and C2-C4 triols, such as ethylene glycol, propylene glycol (PG), 1,3-propanediol, and trimethylolpropane.

[0018] In one embodiment, the glycol ether is diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether (e.g., butyl carbitol), triethylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol phenyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether (DPGME), tripropylene glycol methyl ether (TPGME), dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether (DPGPE), tripropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether It is selected from hexaethylene glycol monophenyl ether, dipropylene glycol methyl ether acetate, and tetraethylene glycol dimethyl ether (TEGDE).

[0019] In one embodiment, the ammonium halide is ammonium chloride or ammonium bromide.

[0020] In one embodiment, the amine is triethylamine. In another embodiment, the amine is a secondary amine. In another embodiment, the amine is selected from diethylamine, diisopropylamine, ethylmethylamine, diethanolamine, N,N-dimethylamine, and N-methyldiethanolamine.

[0021] In one embodiment, the corrosion inhibitor is 5-amino-1,3,4-thiadiazole-2-thiol (ATDT), benzotriazole (BTA), 1,2,4-triazole (TAZ), tolyltriazole, 5-methyl-benzotriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole, benzotriazole carboxylic acid, 3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole, hydroxybenzotriazole, 2-(5-amino-pentyl)-benzotriazole, 1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole, 5-phenylthiol-benzotriazole, halo-benzotriazole (halo=F, Cl, Br) or I), naphthotriazole, 2-mercaptobenzimidazole (MBI), 2-mercaptobenzothiazole, 4-methyl-2-phenylimidazole, 2-mercaptothiazoline, 5-aminotetrazole, pentylenetetrazole, 5-phenyl-1H-tetrazole, 5-benzyl-1H-tetrazole, 2-benzylpyridine, succinimide, maleimide, phthalimide, glutarimide, 2,4-diamino-6-methyl-1,3,5-triazine, thiazole, The compound is selected from azole, triazine, methyltetrazole, 1,3-dimethyl-2-imidazolidinone, 1,5-pentamethylenetetrazole, 1-phenyl-5-mercaptotetrazole, diaminomethyltriazine, imidazolinethione, 4-methyl-4H-1,2,4-triazole-3-thiol, benzothiazole, imidazole, pyrazole, indiazole, adenosine, carbazole, saccharin, and benzoin oxime.Additional corrosion inhibitors include benzalkonium chloride, benzyldimethyldodecylammonium chloride, myristyltrimethylammonium bromide, dodecyltrimethylammonium bromide, hexadecylpyridinium chloride, Aliquat 336 (Cognis), benzyldimethylphenylammonium chloride, Crodaquat TES (Croda Ltd.), and Rewoquat. CPEM (Witco), hexadecyltrimethylammonium p-toluenesulfonate, hexadecyltrimethylammonium hydroxide, 1-methyl-1'-tetradecyl-4,4'-bipyridium dichloride, alkyltrimethylammonium bromide, amprolium hydrochloride, benzethonium hydroxide, benzethonium chloride, benzyldimethylhexadecylammonium chloride, benzyldimethyltetradecylammonium chloride, benzyldodecyldimethylammonium bromide, benzyldodecyldimethylammonium chloride, cetylpyridinium chloride, choline tosylate, dimethyldioctadecylammonium bromide, dodecylethyldimethylammonium bromide, dodecyltrimethylammonium chloride, ethylhexadecyldimethylammonium bromide, Girard's reagent, hexadecyl(2-hydroxyethyl)dimethylammonium dihydrogen phosphate, dexadecylpyridinium bromide cationic quaternary surfactant salts such as hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, methylbenzethonium chloride, Hyamine® 1622, Luviquat™, N,N',N'-polyoxyethylene(10)-N-tallow-1,3-diaminopropane liquid, oxyphenonium bromide, tetraheptylammonium bromide, tetrakis(decyl)ammonium bromide, thonzonium bromide, tridodecylammonium chloride, trimethyloctadecylammonium bromide, 1-methyl-3-n-octylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium tetrafluoroborate, 1-decyl-3-methylimidazolium chloride, tridodecylmethylammonium bromide, dimethyldistearylammonium chloride, and hexamethonium chloride.Other corrosion inhibitors include nonionic surfactants such as PolyFox PF-159 (OMNOVA Solutions), poly(ethylene glycol) ("PEG"), poly(propylene glycol) ("PPG"), PEG-PPG copolymers such as Pluronic F-127 (BASF), anionic surfactants such as dodecylbenzenesulfonic acid, sodium dodecylbenzenesulfonate, and combinations thereof. Quaternary salts can function as both corrosion inhibitors and wetting agents. Quaternary salts are most frequently commercially available as chlorides or bromides, but it will be appreciated that it is easy to ion-exchange the halide anions with non-halide anions such as sulfate, methanesulfonate, nitrate, hydroxide, and similar salts. Such converted quaternary salts are also contemplated herein. In a particularly preferred embodiment, 5-methyl-1H-benzotriazole is known to inhibit the oxidizing activity of oxidizing agents against copper. Alternatively or in addition to 5-methyl-1H-benzotriazole (mBTA), corrosion inhibitors include pyrazoles, benzotriazoles, cationic quaternary surfactant salts, more preferably myristyltrimethylammonium bromide, benzalkonium chloride, hexadecyltrimethylammonium p-toluenesulfonate and hexadecyltrimethylammonium hydroxide, tetrazoles such as 5-benzyl-1H-tetrazole, and combinations thereof.

[0022] In another embodiment, the corrosion inhibitor is selected from myristyltrimethylammonium bromide, benzalkonium chloride, hexadecyltrimethylammonium p-toluenesulfonate, hexadecyltrimethylammonium hydroxide, 5-benzyl-1H-tetrazole, and combinations thereof.

[0023] In one embodiment, the corrosion inhibitor is selected from the group consisting of benzalkonium chloride; dodecylbenzalkonium chloride; alkylbenzene sulfonates; and diphenylsilanol; triethylsilanol; tri-t-butoxysilanol; amino(dimethyl)silanol; aminopropyl diisopropylsilane; aminopropylsilanetriol; (3-aminopropyl)triethoxy-silane; N-(2-aminoethyl)-3-aminopropylsilanetriol; N 1 3,3'-(dimethoxysilylene)bis-(1-propanamine); 1,3-bis(3-aminopropyl)-1,1,3,3-tetraethoxydisiloxane; and N-(6-aminohexyl)aminopropyltrimethoxysilane, as well as combinations thereof.

[0024] In another embodiment, the corrosion inhibitor is present in an amount from about 0.001% to about 2% by weight.

[0025] In one embodiment, the corrosion inhibitor is a mixture of aminopropyl silanetriol and at least one alkylbenzene sulfonate.

[0026] In the above composition, the relative proportions of the components are as follows: a. about 65 to about 80% by weight water; b. about 4 to about 10% by weight of a fluorine compound selected from ammonium fluoride, ammonium hydrogen difluoride, and hexafluorosilicic acid; c. an acid in an amount sufficient to achieve a specified pH of from about -2 to about 6; d. about 1 to about 5 weight percent of a corrosion inhibitor; and e. a water soluble component selected from alcohols, glycols, glycol ethers, ammonium halides, and amines; It is.

[0027] In one embodiment, the fluorine compound is hexafluorosilicic acid.

[0028] Although hexafluorosilicic acid has been observed to hydrolyze with hydrofluoric acid to various forms of amorphous and hydrated silica (e.g., silicon dioxide), the present invention provides the use of hexafluorosilicic acid in aqueous compositions in the presence of certain water-soluble components at a pH of about 1 to about 2 for selective etching (i.e., removal of zirconium oxide in the presence of other materials such as polysilicon, silicon dioxide, silicon nitride, and tungsten), making the compositions particularly useful in the fabrication of high aspect ratio structures comprising these materials.

[0029] As used herein, a "microelectronic device" is a device that includes electronic circuitry and associated structures of very small (e.g., microscale or smaller) dimensions formed thereon. Exemplary microelectronic devices include flat panel displays, integrated circuits, memory devices, solar panels, photovoltaic power generation devices, and microelectromechanical systems (MEMS). A microelectronic device substrate is a structure, such as a wafer (e.g., a semiconductor wafer), that includes one or more microelectronic devices or precursors thereof in a state that is ready to form the final microelectronic device.

[0030] In a second aspect, the present invention provides a method for removing a zirconium oxide or hafnium oxide hard mask from a microelectronic device, comprising the steps of: A. Water; b. a fluorine compound selected from ammonium fluoride, ammonium hydrogen difluoride, and hexafluorosilicic acid; c. one or more acids; d. One or more corrosion inhibitors; and e. a water soluble component selected from alcohols, glycols, glycol ethers, ammonium halides, and amines; and contacting the microelectronic device with a composition having a pH of about -2 to 6 for a time and at a temperature necessary to achieve at least partial removal of the hard mask.

[0031] In other embodiments, the composition is as defined above in the various embodiments.

[0032] It will be appreciated that it is conventional to make concentrated forms of the compositions that are diluted prior to use. For example, the compositions may be manufactured in a more concentrated form and then diluted with at least one solvent prior to use at the manufacturer and / or during use at the fab. The dilution ratio may range from about 0.1 parts diluent:1 part composition concentrate to about 100 parts diluent:1 part composition concentrate. The compositions described herein may be readily formulated by simply adding each ingredient and mixing to homogeneity. Additionally, the compositions may be readily formulated as single package formulations or multi-part formulations, preferably multi-part formulations, that are mixed at or prior to the point of use. The individual parts of the multi-part formulation may be mixed at the tool or in a mixing area / zone such as an in-line mixer or in a storage tank upstream of the tool. It is contemplated that the various parts of the multi-part formulation may include any combination of ingredients / ingredients that when mixed form the desired composition. It is understood that the concentration of each ingredient may vary widely in certain quasi-aqueous compositions, i.e., may be more dilute or more concentrated, and that the quasi-aqueous compositions may variously and alternatively comprise, consist of, or consist essentially of any combination of components consistent with the disclosure herein.

[0033] Thus, in a third aspect, the present invention provides a kit comprising two or more components adapted to form a composition as described herein in one or more containers. The containers of the kit should be suitable for storage and transportation of the composition components (e.g., NOWPaK® containers (Advanced Technology Materials, Inc., Danbury, Connecticut, USA)). The two or more containers comprising the composition components preferably comprise a means for fluidly connecting the components in the one or more containers for blending and dispensing. For example, referring to NOWPaK® containers, the fluidic connection for blending and dispensing may be enabled by applying gas pressure to the outside of the liner in the one or more containers to expel at least a portion of the contents of the liner. Alternatively, gas pressure may be applied to the headspace of a conventional pressurizable container, or a pump may be used to enable the fluidic connection. In addition, the system preferably comprises a dispensing port for dispensing the blended composition to a process tool.

[0034] A substantially chemically inert, impurity-free, flexible, and resilient polymeric film material, such as high density polyethylene, may be used to manufacture a liner for the one or more containers. Desirable liner materials are generally processed without the need for coextrusion or barrier layers and without any pigments, UV inhibitors, or processing materials that may adversely affect the purity requirements for the components placed in the liner. A list of desirable liner materials includes virgin (additive-free) polyethylene, virgin polytetrafluoroethylene (PTFE), polypropylene, polyurethane, polyvinylidene chloride, polyvinyl chloride, polyacetal, polystyrene, polyacrylonitrile, polybutylene, and similar liner materials. Exemplary thicknesses of such liner materials range from about 5 mils (0.005 inches) to about 30 mils (0.030 inches), with a thickness of 20 mils (0.020 inches) being an example.

[0035] With respect to containers for kits, the disclosures of the following patents and patent applications are hereby incorporated by reference in their entirety: U.S. Pat. No. 7,188,644, entitled "APPARATUS AND METHOD FOR MINIMIZING THE GENERATION OF PARTICLES IN ULTRAPURE LIQUIDS"; and U.S. Pat. No. 6,698,619, entitled "RETURNABLE AND REUSABLE, BAG-IN-DRUM FLUID STORAGE AND DISPENSING CONTAINER SYSTEM."

[0036] Compositions as described may be useful in methods for removing high-k hardmask materials such as zirconium oxide and hafnium oxide in the presence of materials such as polysilicon, silicon dioxide, silicon nitride, and tungsten.

[0037] In use, the compositions of the present invention can provide useful etching (i.e., removal) performance based on commercial performance requirements and expectations, and can provide improved performance in terms of etch rate and selectivity of high-k materials, such as zirconium oxide and hafnium oxide, relative to materials such as polysilicon, silicon dioxide, silicon nitride, and tungsten, as compared to comparative etching compositions.

[0038] Methods of etching microelectronic device substrates are known in the semiconductor manufacturing art and can be performed on known and commercially available equipment. Generally, to etch a substrate and selectively remove material at the substrate surface, an etching composition can be applied to the surface and contacted with the surface structures to chemically selectively remove the particular structures.

[0039] In the etching process, the composition can be applied to the surface in any suitable manner, such as by spraying the etching composition onto the surface; by immersing the substrate in the etching composition (in a static or dynamic volume of the composition); by contacting the surface with another material (e.g., a pad, or fibrous adsorbent applicator element) that has absorbed the etching composition; by contacting the substrate with a volume of the etching composition in a circulator pool; or by any other suitable means, method, or technique, whereby the etching composition is brought into removal contact with the surface of the microelectronic device substrate, including high-k hardmask materials such as zirconium oxide or hafnium oxide. Application can be performed in a batch or single wafer apparatus for dynamic or static cleaning.

[0040] Useful etching process conditions (e.g., time and temperature) can be any that are deemed effective or advantageous. In general, the etching composition is contacted with the surface, for example, by immersion in a bath of the etching composition, for a time sufficient to selectively remove the desired hard mask material(s). The time of exposure to the etching composition and the temperature of the etching composition can be effective to remove the desired amount of hard mask from the surface of the substrate. The time for the etching step should not be too short, because this may mean that the etching rate of the hard mask is too fast, which may cause process control difficulties and quality degradation of the microelectronic device at the end of the etching step. Of course, it is advantageous that the time required for the etching step is not too long to allow good efficiency and throughput of the etching method and semiconductor manufacturing line. Examples of useful times for the etching step can be in the range of about 0.5 minutes to about 3 minutes, or about 1 minute to about 2 minutes, at a temperature in the range of about 30° C. to about 60° C. Such contact times and temperatures are exemplary, and any other suitable time and temperature conditions that are effective to achieve the desired removal selectivity may be employed.

[0041] Although several exemplary embodiments of the present disclosure have been described above, those skilled in the art will readily appreciate that other embodiments may be made and used within the scope of the claims set forth herein. Numerous advantages of the present disclosure, which are covered by this document, have been set forth in the foregoing description. However, it will be understood that in many respects, the present disclosure is only exemplary. The scope of the present disclosure is, of course, defined by the language in which the claims are expressed.

Claims

1. a. water; b. a fluorine compound selected from ammonium fluoride, ammonium hydrogen difluoride, and hexafluorosilicic acid; c. one or more acids; d. dodecylbenzenesulfonic acid and aminopropylsilanetriol; e. a water soluble component selected from alcohols, glycols, glycol ethers, ammonium halides, and amines; and having a pH of about -2 to 6.

2. The composition according to claim 1 , wherein the fluorine compound is hexafluorosilicic acid.

3. The composition described in claim 1, wherein the water content is about 65 to about 80% by weight of the composition, the fluorine compound content is about 4 to about 10% by weight of the composition, and the dodecylbenzenesulfonic acid and aminopropylsilanetriol content is about 1 to about 5% by weight of the composition.

4. The composition of claim 1, wherein the water-soluble component comprises n-butanol.

5. 1. A method for removing a zirconium oxide or hafnium oxide hard mask from a microelectronic device, comprising: a. water; b. a fluorine compound selected from ammonium fluoride, ammonium hydrogen difluoride, and hexafluorosilicic acid; c. one or more acids; d. dodecylbenzenesulfonic acid and aminopropylsilanetriol; and e. a water soluble component selected from alcohols, glycols, glycol ethers, ammonium halides, and amines; contacting the microelectronic device with a composition having a pH of about -2 to 6 for a time and at a temperature necessary to effect at least partial removal of said hard mask.