Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 1 of 15
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 1 of 15
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`EXHIBIT 13
`EXHIBIT 13
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`case 620-cv-01216-a08 Document MARIFATETATAEMT
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 2 of 15
`US006645702B1
`
`United States Patent
`US 6,645,702 BI
`(10) Patent No.:
`(12)
`Rangarajanet al.
`*Nov. 11, 2003
`(45) Date of Patent:
`
`(54)
`
`(75)
`
`TREAT RESIST SURFACE TO PREVENT
`PATTERN COLLAPSE
`
`Inventors: Bharath Rangarajan, Santa Clara, CA
`(US); Michael K. Templeton, Atherton,
`CA (US); BhanwarSingh, Morgan
`Hill, CA (US)
`
`(73)
`
`Assignee:
`
`Advanced Micro Devices, Inc.,
`Sunnyvale, CA (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`US.C. 154(b) by 99 days.
`
`1/1996 Nakato et al. 0... 428/451
`5,486,424 A
`10/1997 Sugimotoetal. ........... 396/611
`5,678,116 A
`
`...... « 430/313
`1/1998 Stauffer et al.
`5,707,783 A
`
`. 438/597
`3/1999 Daietal.
`.....
`5,877,075 A
`9/2002 Rangarajan .............. 430/313
`6,451,512 Bl *
`OTHER PUBLICATIONS
`
`Cae, Heidi, B., et al. “Comparison of Resist Collapse
`Properties for DUV and 193 nm Resist Platforms,” EIPBN
`2000 #141.
`
`Domke, Wolf. D. “Pattern Collapse in High Aspect Ratio
`DUV—and 193nm Resists.”
`
`* cited by examiner
`
`This patent is subject to a terminal dis-
`claimer.
`
`Primary Examiner—Kathleen Duda
`(74) Attorney, Agent, or Firm—Amin & Turocy, LLP
`
`(21)
`
`(22)
`
`(63)
`
`(61)
`(52)
`(58)
`
`(56)
`
`Appl. No.: 10/050,438
`
`Filed:
`
`Jan. 16, 2002
`
`Related U.S. Application Data
`
`Continuation-in-part of application No. 09/565,691, filed on
`May1, 2000.
`
`Unt, C07 oieeeeccceecscesseseeseeseeseereeseeseeseesees GO03F 7/00
`US. Che oe 430/313; 430/296; 430/328
`Field of Search ............0..cc cece 430/296, 311,
`430/313, 315, 323, 324, 325, 328
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,751,170 A
`5,407,786 A
`5,427,649 A
`
`6/1988 Mimura ......... cece 430/296
`4/1995 Ito et al. wees 430/313
`
`........... 156/661.11
`6/1995 Kim etal.
`
`(57)
`
`ABSTRACT
`
`The present invention relates to systems and methods for
`increasing the hydrophobicity of patterned resists. In one
`embodiment, the present invention relates to a method of
`processing an ultra-thin resist,
`involving depositing the
`ultra-thin photoresist over a semiconductor substrate; irra-
`diating the ultra-thin resist with electromagnetic radiation;
`developing the ultra-thin resist with a developer to form a
`patterned resist, the patterned resist having a surface with a
`first hydrophobicity; contacting the patterned resist with a
`transition solvent to provide the surface of the patterned
`resist with a second hydrophobicity, wherein the second
`hydrophobicity is greater than the first hydrophobicity and
`contact of the patterned resist with the transition is con-
`ducted between developing the ultra-thin resist and rinsing
`patterned resist; and rinsing the patterned resist having the
`second hydrophobicity with an aqueous solution.
`
`22 Claims, 4 Drawing Sheets
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`my
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`14
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`12
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`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 3 of 15
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 3 of 15
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`U.S. Patent
`
`Nov.11, 2003
`
`Sheet 1 of 4
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`US 6,645,702 B1
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` FIG. 1
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`FIG. 2
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`FIG. 3
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`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 4 of 15
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 4 of 15
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`U.S. Patent
`
`Nov.11, 2003
`
`Sheet 2 of 4
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`US 6,645,702 B1
`
`my
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`my
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`FIG. 4
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`FIG. 5
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`FIG. 6
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`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 5 of 15
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 5of15
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`U.S. Patent
`
`Nov.11, 2003
`
`Sheet 3 of 4
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`US 6,645,702 B1
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`32
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`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 6 of 15
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 6 of 15
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`U.S. Patent
`
`Nov.11, 2003
`
`Sheet 4 of 4
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`US 6,645,702 B1
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`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 7 of 15
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 7 of 15
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`US 6,645,702 B1
`
`1
`TREAT RESIST SURFACE TO PREVENT
`PATTERN COLLAPSE
`
`RELATED APPLICATIONS
`
`This application is a continuation-in-part of application
`Ser. No. 09/565,691 filed on May 1, 2000, which is hereby
`incorporated by reference.
`
`TECHNICAL FIELD
`
`The present invention generally relates to increasing the
`resistance of a resist to pattern collapse after development.
`In particular, the present invention relates to functionalizing
`a thin resist with a transition solvent to render its surface
`
`hydrophobic, which in turn increasesits resistance to pattern
`collapse during post-development rinse/dry cycles.
`
`BACKGROUND ART
`
`In the semiconductor industry, there is a continuing trend
`toward higher device densities. To achieve these high
`densities, there has been and continues to be efforts toward
`scaling down the device dimensions on semiconductor
`wafers. In order to accomplish such high device packing
`density, smaller and smaller features sizes are required. This
`includes the width and spacing of interconnecting lines and
`the surface geometry such as corners and edges of various
`features. Since numerousinterconnecting lines are typically
`present on a semiconductor wafer, the trend toward higher
`device densities is a notable concern.
`
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`terned photoresists simply do not withstand the physical
`strain imposed bythe post-developmentrinse and dry steps.
`For example, pattern collapse due to water rinse, dry cycles,
`and spinning action associated with such steps, result in poor
`pattern transfer. In many instances the relatively thin pat-
`terned photoresists are destroyed or partially destroyed
`during deionized water rinsing. As a result,
`it
`is often
`necessary to employ the use of hardmasks when using thin
`photoresists in semiconductor processing techniques.
`Improved lithography procedures providing improved reso-
`lution and improvedresistance to pattern collapse are there-
`fore desired.
`
`SUMMARYOF THE INVENTION
`
`The present invention generally provides systems and
`methods that lead to improved pattern collapse resistance,
`improved critical dimension control and/or improved reso-
`lution in patterned thin and ultra-thin resists. Since it is
`possible to enhance the pattern collapse resistance of thin
`and ultra-thin photoresists, the present invention provides
`improved methods for processing layers underneath pat-
`terned ultra-thin photoresists including metal layers, dielec-
`tric layers, and silicon layers. The methods of the present
`invention makeit possible to consistently process underly-
`ing layers through trenches, holes and other openings on the
`order of about 0.18 um or less in size. The methods of the
`present invention also make it possible to avoid the use of
`hardmasks when using ultra-thin photoresists. As a result,
`the present
`invention effectively addresses the concerns
`raised by the trend towards the miniaturization of semicon-
`ductor devices.
`
`The requirement of small features, such as metal lines,
`with close spacing between adjacent features requires high
`the present invention relates to a
`In one embodiment,
`resolution photolithographic processes. In general, lithogra-
`method of processing an ultra-thin resist, involving the steps
`phyrefers to processes for pattern transfer between various
`media. It is a technique used for integrated circuit fabrication
`of depositing the ultra-thin photoresist over a semiconductor
`
`in whichasiliconslice, the wafer, is coated uniformly with substrate; irradiating the ultra-thin resist; developing the
`
`a radiation-sensitive film, the resist, and an exposing source
`ultra-thin resist with a developer to form a patterned resist,
`(such as optical light, X-rays, or an electron beam) illumi-
`the patterned resist having a surface with a first hydropho-
`nates selected areas of the surface through an intervening
`bicity; contacting the patterned resist with a transition sol-
`master template, the photomask,for a particular pattern. The
`ventin a liquid state within about 5 minutes after developing
`lithographic coating is generally a radiation-sensitized coat-
`to provide the surface of the patterned resist with a second
`ing suitable for receiving a projected image of the subject
`hydrophobicity, wherein the second hydrophobicity is
`pattern. Once the image is projected,it is indelibly formed
`greater than the first hydrophobicity and contact of the
`in the coating. The projected image maybeeither a negative
`patterned resist with the transition is conducted between
`or a positive of the subject pattern. Exposure of the coating
`developing the ultra-thin resist and rinsing patternedresist;
`through the photomask causes a chemical transformation in
`and rinsing the patterned resist having the second hydro-
`the exposed areas of the coating thereby making the image
`phobicity with an aqueoussolution.
`area either more or less soluble (depending on the coating)
`In another embodiment, the present invention relates to a
`in a particular solvent developer. The more soluble areas are
`method of increasing the pattern collapse resistance of an
`removed in the developing process to leave the pattern
`ultra-thin resist, involving the steps of irradiating the ultra-
`image in the coating as less soluble polymer.
`thin resist; developing the ultra-thin resist to form a pat-
`Projection lithography is a powerful and essential tool for
`ternedresist; contacting the patterned resist with a transition
`microelectronics processing. However, lithography is not
`solvent in a liquid state within about 5 minutes after devel-
`without limitations. Patterning features having dimensions
`oping to provide the patterned resist with a hydrophobic
`of about 0.25 um, 0.18 um or less with acceptable resolution
`surface, wherein contact of the patterned resist with the
`is difficult. This is because photoresist layers used in lithog-
`transition is conducted between developing the ultra-thin
`raphy typically have thicknesses on the order of 7,000 Aand
`resist and rinsing patterned resist; and rinsing the patterned
`higher. Such relatively thick photoresist layers are not con-
`resist having the hydrophobic surface with an aqueous
`solution.
`ducive to making small patterned dimensions with good
`resolution.
`In another embodiment, the present invention relates to a
`Usingrelatively thin photoresists (such as less than about
`semiconductor processing system, containing a processing
`5,000 A) enables the patterning of smaller and smaller
`chamber operable to treat a patterned resist havingafirst
`dimensions. However, insufficient resistance to pattern col-
`hydrophobicity; a supply of a transition solvent for contact
`lapse during post-developmentrinse and dry cycles is asso-
`with the patternedresist to provide a second hydrophobicity;
`ciated with using thin photoresists. Insufficient resistance to
`and a measurement system for in situ measuring of hydro-
`pattern collapse is also associated with smaller and smaller
`phobicity of the patterned resist and for providing a mea-
`pitches (of patterned photoresists). The relatively thin pat-
`surementsignal indicative of the measured hydrophobicity.
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`US 6,645,702 B1
`
`3
`BRIEF DESCRIPTION OF DRAWINGS
`
`FIG. 1 illustrates a cross-sectional view of droplets of
`liquid on a surface and angles representing a measurement
`of hydrophobicity.
`FIG. 2 illustrates a cross-sectional view of a method
`
`according to one aspect of the present invention.
`FIG. 3 illustrates a cross-sectional view of a method
`according to another aspect of the present invention.
`FIG. 4 illustrates a cross-sectional view of a method
`
`according to yet another aspect of the present invention.
`FIG. 5 illustrates a cross-sectional view of a method
`accordingtostill yet another aspect of the present invention.
`FIG. 6 illustrates a cross-sectional view of a method
`
`according to another aspect of the present invention.
`FIG. 7 is a diagramatic block representation of a system
`in accordance with one aspect of the present invention.
`FIG. 8 is a functional block diagram of a a system in
`accordance with another aspect of the present invention.
`
`DISCLOSURE OF THE INVENTION
`
`The present invention involves etching extremely fine
`patterns using an ultra-thin resist having improved pattern
`collapse resistance. The present invention morespecifically
`involves contacting a freshly developed ultra-thin resist with
`a transition solvent which enableshigh resolution patterning
`of underlying layers having features on the order of about
`0.18 wm or less, and even about 0.13 wm or less. The
`patterned andtreated ultra-thin resist resists pattern degra-
`dation problems and insufficient pattern collapse resistence
`commonly associated with thin resists. Especially as the
`pitch of patterned resists decreases in view of the trend
`toward higher device densities,
`the problem of pattern
`collapse increases;
`thus,
`the present
`invention promotes
`advancementin the trend toward higher device densities.
`As a result of the present
`invention, pattern collapse
`resistance to at least one of water rinse, drying, and torsional
`spinning forces is improved.
`Improved pattern collapse
`resistance permits the ultra-thin resists processed in accor-
`dance with the present
`invention to be used, without
`hardmasks,
`in processing underlying layers with precise-
`ness. Resolution and critical dimension control are also
`improved bythe treated ultra-thin resists.
`An ultra-thin resist is initially provided over a semicon-
`ductor substrate. The semiconductor substrate may include
`any suitable semiconductor material (one or more layers of
`semiconductor materials), for example, a monocrystalline
`silicon substrate. Semiconductor substrates may include of
`one or more layers including substrate layers, diffusion
`regions, dielectric layers such as oxides and nitrides, metal
`layers, devices, polysilicon layers, and the like (all of which
`are collectively termed semiconductor layers). The top layer
`of the semiconductor substrate serves as the underlying layer
`once an ultra-thin photoresist layer is formed thereover.
`An ultra-thin photoresist layer is formed over the semi-
`conductor substrate. The ultra-thin photoresist is deposited
`over the semiconductor substrate using any suitable tech-
`nique. For example, the ultra-thin photoresist is deposited
`using conventional spin-coating or spin casting techniques.
`Ultra-thin photoresists in accordance with the present
`invention have a thickness of about 5,000 A orless. In one
`embodiment, the ultra-thin photoresist layer has a thickness
`from about 200 A to about 5,000 A. In another embodiment,
`the ultra-thin photoresist layer has a thickness from about
`300 A to about 3,000 A (about 3,000 A or less). In yet
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`another embodiment, the ultra-thin photoresist layer has a
`thickness from about 400 A to about 2,500 A (about 2,500
`A orless).
`The ultra-thin photoresist layer has a thickness suitable
`for functioning as a mask for processing an underlying layer
`and for forming patterns or openings in the developed
`ultra-thin photoresist layer that are about 0.18 um orless.
`Processing the underlying layer includes one or more of
`etching, implantation, deposition, or other operations. Since
`the ultra-thin photoresist layer is relatively thin compared
`with I-line photoresists and other photoresists,
`improved
`critical dimension control is realized.
`
`Ultra-thin resists are typically processed using small
`wavelength radiation. As used herein, small wavelength
`radiation means electromagnetic radiation having a wave-
`length of about 250 nm orless, including e-beams and
`X-rays. In one embodiment, small wavelength radiation
`includes electromagnetic radiation having a wavelength of
`about 200 nm orless. In another embodiment, small wave-
`length radiation includes extreme UV electromagnetic radia-
`tion having a wavelength of about 25 nm or less. In yet
`another embodiment, small wavelength radiation includes
`extreme UVelectromagnetic radiation having a wavelength
`of about 15 nm orless, including e-beams and X-rays.
`Small wavelength radiation increases precision and thus
`the ability to improve critical dimension control and/or
`resolution. Specific examples of wavelengths to which the
`ultra-thin photoresists are sensitive (undergo chemicaltrans-
`formation enabling subsequent development) include about
`248 nm, about 193 nm, about 157 nm, about 13 nm, about
`11 nm, about 1 nm, and e-beams. Specific sources of
`radiation include KrF excimerlasers having a wavelength of
`about 248 nm, a XeHg vapor lamp having a wavelength
`from about 200 nm to about 250 nm, mercury-xenon arc
`lampshaving a wavelength of about 248 nm, an ArF excimer
`laser having a wavelength of about 193 nm, an F, excimer
`laser having a wavelength of about 157 nm, extreme UV
`light having wavelengths of about 13.5 nm and/or about 11.4
`nm, and X-rays having a wavelength of about 1 nm.
`In embodiments where the patterns or openings formed in
`the subsequently developed ultra-thin photoresist layer are
`from about 0.1 um to about 0.15 wm, a 157 nm sensitive
`photoresist or a 193 nm sensitive photoresist is preferably
`employed. In embodiments where the patterns or openings
`formed in the subsequently developed ultra-thin photoresist
`layer are about 0.1 um orless, a 13 nm sensitive photoresist
`or an 11 nm sensitive photoresist (extreme UV photoresist)
`is preferably employed.
`Positive or negative ultra-thin photoresists may be
`employed in the methods of the present invention. General
`examples of ultra-thin photoresists include those containing
`a partially t-butoxycarbonyloxy substituted poly-p-
`hydroxystyrene, melamine-formaldehyde polymers,
`polyvinylpyrrolidone, polymethylisoprenylketone,
`a
`novolak, a polyvinylphenol, polymers of hydroxystyrene
`and acrylate, methacrylate polymers or a mixture of acrylate
`polymers and methacrylate polymers. Further specific
`examples include poly(p-tert-butoxycarbonyloxy-a-
`methylstyrene), poly(ptert-butoxycarbonyloxystyrene), poly
`(tert-butyl p-vinylbenzoate), poly(tert-butyl
`pisopropenylphenyloxyacetate), and poly(tert-butyl
`methacrylate). Photoresists are commercially available from
`a numberof sources, including Shipley Company, Kodak,
`Hunt, Arch Chemical, Aquamer, JSR Microelectronics,
`Hoechst Celanese Corporation, and Brewer.
`After the ultra-thin resist is deposited over a semiconduc-
`tor substrate,
`the structure including the semiconductor
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`US 6,645,702 B1
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`5
`substrate and ultra-thin resist is optionally heated. Heating
`serves to promote removal of excess solvent employed to
`deposit the ultra-thin resist over the semiconductor sub-
`strate.
`
`The ultra-thin resist layer is then selectively exposed to
`actinic radiation. In particular, the ultra-thin resist layer is
`exposed to a pattern of radiation having a relatively small
`wavelength (for example,less than 250 nm); thatis, selected
`portions of the ultra-thin resist layer are exposed to actinic
`radiation through a mask, leaving the ultra-thin resist layer
`with exposed and unexposed portions. Actinic radiation
`includesrelatively small wavelength less than 250 nm and
`e-beams. A numberof exemplary wavelengths are described
`above in connection with the ultra-thin resists.
`
`Following an image-wise exposure to actinic radiation,
`the ultra-thin photoresist layer is developed to provide a
`patterned ultra-thin photoresist. The selectively exposed
`ultra-thin photoresist layer is developed by contact with a
`suitable developer that removes either the exposed or unex-
`posed portions of the ultra-thin photoresist layer. The iden-
`tity of the developer depends upon the specific chemical
`constitution of the ultra-thin photoresist layer. Typically, for
`example, an aqueous alkaline solution may be employed to
`remove unexposed portions of the ultra-thin photoresist
`layer. Alternatively, one or more of dilute aqueous acid
`solutions, hydroxide solutions, water, organic solvent solu-
`tions may be employed to remove selected portions of the
`ultra-thin photoresist layer.
`Following pattern formation or development, and prefer-
`ably immediately following pattern formation (within about
`5 minutes or within about 1 minute), and before water rinse
`and drying, the ultra-thin resist layer is contacted with a
`transition solvent. Contacting the ultra-thin resist with a
`transition solvent renders the surface of the patterned ultra-
`thin resist hydrophobic,or at least increasingly hydrophobic.
`While not wishing to be bound by any theory, in some
`instances it is believed that the increasingly hydrophobic
`surface of the patterned resist permits aqueousfluids to pass
`thereover with little resistance, thereby leading to decreased
`physical damage.
`The transition solvent is any chemical compound nor-
`mally in the liquid state at room temperature that can render
`the surface of a patterned ultra-thin resist hydrophobic or
`increasingly hydrophobic. For example, the transition sol-
`vent maya silicon containing compound containing a mol-
`ecule of silicon that can be incorporated into the surface of
`a patterned ultra-thin resist thereby rendering it hydropho-
`bic. The transition solvent may alternatively be an organic
`solvent that leaves a microscopic hydrophobic film on the
`patterned ultra-thin resist.
`The transition solvent is a silicon containing compound
`and/or an organic solvent. Silicon containing compounds
`include silane and organosilicon compounds. Organosilicon
`compounds include monofunctional organosilicon
`compounds, difunctional organosilicon compounds, and
`polyhinctional organosilicon compounds. The silicon con-
`taining compound(s) employed are in the form of a liquid.
`Specific examples of silicon containing compounds
`include silane, hexamethyldisilazane (HMDS), trimethylsi-
`lyldiethylamine (TMSDEA),
`trimethylsilyldimethylamine
`(TMSDMA), dimethylsilyldiethylamine (DMADEA), dim-
`ethylsilyldimethylamine (DMSDMA),
`tetramethyldisila-
`zane (TMDS),trimethylmethoxysilane (TMMS), trimethyl-
`ethoxysilane (TMES),
`trimethylpropoxysilane (TMPS),
`trimethyl acetoxysi
`lane (TMAS), bis(dimethylamino)
`dimethylsilane (BDMADMS), bis(dimethylamino)
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`methylsilane (BAMS), methyldimethylaminoethoxysilane
`(MDAES), methyldimethoxysilane (MDMS), methyldiethy-
`oxysilane (MDES), dimethyldimethoxysilane (DMDS),
`dimethyldiethoxysilane (DMES), and methyltrimethoxysi-
`lane (MTMS), and the like. In one embodiment, one silicon
`containing compound is employed in or as the transition
`solvent. In another embodiment, two or more silicon con-
`taining compounds are employed in or as the transition
`solvent. In yet another embodiment, three or more silicon
`containing compoundsare employed in oras the transition
`solvent.
`
`The monofunctional organosilicon compound has one or
`moresilicon atoms and a single hydrolyzable moiety bonded
`to a silicon atom. The compound may thus contain a single
`silicon atom bonded to a single hydrolyzable moiety. In
`cases involving a hydrolyzable moiety that has a valence of
`twoorgreater, the organosilicon compound maycontain two
`or more silicon atoms bonded to a common hydrolyzable
`moiety that is the only hydrolyzable moiety in the com-
`pound. The term “monofunctional”is used to denote that the
`reaction between the organosilane and the polymerresults in
`silicon atoms each bearing only a single linkage to the
`polymerat the location of a reactable group on the polymer,
`even if the organosilicon compound reactant contains more
`than onesilicon atom. Thus, the monofunctional organosili-
`con compound doesnot crosslink the resist polymer chains.
`The di- or polyfunctional organosilicon compound has
`one or more silicon atoms and at least two hydrolyzable
`moieties. Upon reaction with the reactable groups on the
`resist polymer,
`the organosilicon compound joins two or
`moreof the reactable groups, thereby crosslinking the poly-
`mer and making it hydrophobic. The organosilicon com-
`pound maythus contain a single silicon atom bondedto two
`or more hydrolyzable moieties, or two silicon atoms joined
`by a non-hydrolyzable linkage but each bonded individually
`to a separate hydrolyzable moiety, or other variations. The
`term “di- or polyfunctional” is used to denote that
`the
`reaction between the organosilicon compound andtheresist
`polymerresults in a silicon atom crosslinking the polymer
`chains by simultaneously bondingto the locations of two or
`more reactable groups on different chains to make the
`surface hydrophobic.
`The term “hydrolyzable group” denotes any group that
`when bonded to a silicon atom can be cleaved from the
`
`silicon atom upon reaction of the organosilicon compound
`with the reactable group on the resist polymer. Examples of
`such hydrolyzable groups are amino (—NH,), alkylamino
`(—NHR, where R is alkyl), dialkylamino (—NR,, Ro,
`where R, and R, are independently alkyl), alkanoylamino
`(—NHC(O)R,whereR is alkyl), alkoxy (—OR,where R is
`alkyl), and alkanoyloxy (—OC(O)R, where R is alkyl).
`Specific examples are dimethylamino, diethylamino,
`methoxy, ethoxy, propoxy, acetoxy, propionyloxy (—OC(O)
`C.H;), and butyryloxy (—OC(O)C3H,).
`Suitable transition solvents that are organic solvents
`include ketones such as acetone, methyl ethyl ketone,
`methyl isobutyl ketone, mesityl oxide, methyl amyl ketone,
`cyclohexanone and other aliphatic ketones; esters such as
`methyl acetate, ethyl acetate, iso-amyl acetate, alkyl car-
`boxylic esters; ethers such as methyl t-butyl ether, dibutyl
`ether, methyl phenyl ether and other aliphatic or alkyl
`aromatic ethers; glycol ethers such as ethoxy ethanol,
`butoxy ethanol, ethoxy-2-propanol, propoxy ethanol, butoxy
`propanol and other glycol ethers; glycol ether esters such as
`butoxy ethoxy acetate, ethyl 3-ethoxy propionate and other
`glycol ether esters; alcohols such as methanol, ethanol,
`propanol, iso-propanol, butanol, iso-butanol, amyl alcohol
`
`

`

`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 10 of 15
`Case 6:20-cv-01216-ADA Document 41-13 Filed 10/06/21 Page 10 of 15
`
`US 6,645,702 B1
`
`7
`and other aliphatic alcohols; aromatic hydrocarbons such as
`benzene, toluene, xylene, and other aromatics or mixtures of
`aromatic solvents, naphthalene and mineral spirits, and nitro
`alkanes such as 2-nitropropane. Mixtures of two or more
`transition solvents may be employed.
`The timethat the transition solvent is contacted with the
`patterned ultra-thin resist layer is sufficient to render the
`surface of the ultra-thin resist hydrophobic or increase the
`hydrophobicity of the surface to improve the pattern col-
`lapse resistance thereof. In one embodiment, the transition
`solvent is contacted with the ultra-thin resist layer for a time
`from at least about 1 second, or from about 1 second to about
`1 hour. In another embodiment, the silicon containing com-
`pound is contacted with the ultra-thin resist layer for a time
`from at least about 5 seconds, or from about 5 seconds to
`about 5 minutes. In yet another embodiment,
`the silicon
`containing compound is contacted with the ultra-thin resist
`layer for a time from at least about 10 seconds,or from about
`10 seconds to about 2 minutes.
`
`The temperature at which the transition solvent is con-
`tacted with the patterned ultra-thin resist layer is sufficient to
`render the surface of the ultra-thin resist hydrophobic or
`increase the hydrophobicity of the surface to improve the
`pattern collapse resistance thereof. In one embodiment, the
`transition solvent is contacted with the ultra-thin resist layer
`at a temperature from about 10° C.
`to about 125° C. In
`another embodiment, the transition solvent is contacted with
`the ultra-thin resist layer at a temperature from about 20° C.
`to about 100° C. In yet another embodiment, the transition
`solvent is contacted with the ultra-thin resist layer at a
`temperature from about 25° C. to about 75° C.
`Optionally in one embodiment, the transition solvent is
`contacted with the patterned ultra-thin resist layer in an UV
`or ozone environment. In one embodiment, the transition
`solvent is contacted with the patterned ultra-thin resist layer
`under UV light.
`In another embodiment,
`the transition
`solvent is contacted with the patterned ultra-thin resist layer
`under an ozone containing atmosphere.
`In yet another
`embodiment,
`the transition solvent is contacted with the
`patterned ultra-thin resist layer under UV light and an ozone
`containing atmosphere.
`the transition solvent is
`Generally speaking, however,
`contacted with the patterned ultra-thin resist layer under an
`atmosphere containing one or more of air, an inert gas,
`ozone, and oxygen. Inert gases include the noble gases, such
`as helium, neon, argon, krypton and xenon, and nitrogen.
`An ozone containing atmosphere contains at least about
`5% by weight ozone (O3). In another embodiment, the ozone
`containing atmosphere contains at
`least about 10% by
`weight ozone. In yet another embodiment, the ozone con-
`taining atmosphere contains at least about 20% by weight
`ozone. The ozone containing atmosphere may additionally
`contain inert gases and/or other gases that do not effect the
`formation of a hydrophobic surface on the patterned ultra-
`thin resist. The ozone gas may be derived from any suitable
`ozone source. For example, ozone may be derived from
`oxygen using an ozone generator. Methods of making ozone
`are knownin theart.
`
`While not wishing to be bound by any theory, in some
`instances it is believed that the UV or ozone environment
`
`accelerates rendering the surface of the patterned ultra-thin
`resist hydrophobic or increase the hydrophobicity of the
`surface the ultra-thin resist, which in turn, increases the
`pattern collapse resistance of the patterned ultra-thin resist.
`Hydrophobicity refers to the physical property of a sur-
`face to dislike or
`repel water. Hydrophobicity can be
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`described in more quantitative terms by using contact angle
`measurements. Referring to FIG. 1, the contact angle @ is
`defined by the equilibrium forces that occur when a liquid
`sessile drop 3, 4 is placed on a smooth surface 2. The tangent
`5, 6 to the surface 2 of the convex liquid drop 3, 4 at the point
`of contact among the three phases(solid, liquid, and vapor)
`is the contact angle 0,, 6, as illustrated in FIG. 1. Young’s
`equation, F=yp cos @ where F is wetting force, y is liquid
`surface tension, and p is wetting perimeter, defines the
`relationship between the surface tension of the solid-vapor
`(vector along surface 2 away from center of drop 3, 4),
`solid-liquid (vector along surface 2 toward center of drop 3,
`4), and liquid-vapor (tangent 5, 6).
`For purposesof this invention, hydrophobic surfaces have
`contact angles of about 90° or greater.
`In another
`embodiment, hydrophobic surfaces have contact angles of
`about 100° or greater. Increasing the hydrophobicity means
`increasing the contact angle, even if the increased contact
`angle is less than about 90°, for example, increasing contact
`angle from 35° to 75°. Referring again, to FIG. 1, drop 3 is
`positioned on a hydrophobic surface as 8, is greater than
`about 90°; while drop 4 is not positioned on a hydrophobic
`surface as @, is less than 90° (although the hydrophobicity
`of the surface may have been increased).
`Somesurfaces change their surface energy upon contact
`with water. Dynamic contact angle measurements provide
`both an advancing and receding contact angle. The advanc-
`ing contact angle is a measurement of the surface hydro-
`phobicity upon initial contact with a liquid, while the
`receding contact angle measures the hydrophobicity after the
`surface is wetted with a liquid. Thus, for the purposesofthis
`invention, a hydrophobic surface has an advancing and/or
`receding contact angle of about 90° or greater.
`The dynamic contact angles referred to herein are based
`on a gravimetric principle of the Wulhelmyplate technique
`and are determined by measurement on the Dynamic Con-
`tact Angle Instrument which can measure both advancing
`and receding contact angles. Adynamic contact angle analy-
`sis system (model DCA 315) from ATI Cahn Instruments
`Inc. can be used for contact angle measurements referred to
`herein. The data analysis can be made with a WinDCA
`software for W