Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 1 of 16
`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 1 of 16
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`EXHIBIT 14
`EXHIBIT 14
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`

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`case 620-cv-01216-a08 Document MMIFATEAT
`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 2 of 16
`US006746973B1
`
`a2) United States Patent (10) Patent No.:|US 6,746,973 B1
`
`Labelle et al.
`(45) Date of Patent:
`Jun. 8, 2004
`
`
`(54) EFFECT OF SUBSTRATE SURFACE
`TREATMENT ON 193 NM RESIST
`PROCESSING
`
`3/2003 Olsen et ale veces 438/7
`2003/0045008 Al *
`FOREIGN PATENT DOCUMENTS
`
`(75)
`
`Inventors: Catherine B. Labelle, San Jose, CA
`(US); Ernesto Gallardo, Stockton, CA
`(US); Ramkumar Subramanian,
`Sunnyvale, CA (US); Jacques
`Bertrand, Capitola, CA (US)
`
`(73) Assignee: Advanced Micro Devices, Inc.,
`Sunnyvale, CA (US)
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`US.C. 154(b) by 0 days.
`
`(21) Appl. No.: 10/212,985
`
`(22)
`
`Filed:
`
`Aug. 5, 2002
`
`Int. C1? vee HO1L 21/302; HOIL 21/461
`(51)
`(52) U.S. Cle ceececssssssssessseees 438/948; 438/694; 438/724;
`438/725
`(58) Field of Search oo... eee 438/778, 779,
`438/780, 781, 798, 948, 949, 724, 725,
`744, 894, 723; 430/311, 313, 314, 317
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`JP
`
`10186672
`
`*
`
`7/1998
`
`* cited by examiner
`
`Primary Examiner—Jack Chen
`Assistant Examiner—Thanbhha Pham
`(74) Attorney, Agent, or Firm—Amin & Turocy, LLP
`
`(57)
`
`ABSTRACT
`
`Oneaspect of the present invention relates to a system and
`method for mitigating surface abnormalities on a semicon-
`ductor structure. The method involves exposing the layer to
`a first plasma treatment in order to mitigate surface inter-
`actions between the layer and a subsequently formed pho-
`toresist without substantially etching the layer,
`the first
`plasma comprising oxygen and nitrogen; forming a pat-
`terned photoresist over the treated layer, the patterned pho-
`toresist being formed using 193 nm or lower radiation; and
`etching the treated layer through openings of the patterned
`photoresist. The system and methodalso includes a monitor
`processor for determining whether the plasma treatment has
`been administered and for adjusting the plasma treatment
`components. The monitor processor transmits a pulse,
`receives a reflected pulse response and analyzes the
`response. An optional second plasma treatment comprising
`nitrogen and hydrogen may be administered after the first
`plasma treatment but before forming the photoresist.
`
`8/2000 Gabriel ......0.... eee 430/318
`6,103,457 A
`2001/0045646 Al * 11/2001 Shields et al. 0... 257/734
`
`29 Claims, 6 Drawing Sheets
`
`260
`
` PLASMA
`
`TREATMENT
`
`COMPLEX
`
`
`
`PLASMA
`TREATMENT
`COMPONENTS
`
` MONITOR PROCESSOR
`OUTPUT
`“o>
`
`
`
`4
`
`em 290
`|
`280~,]
`I
`rk
`REFLECTED
`275 TRANSMITTED||
`'
`PULSE
`PULSE
`RESPONSE
`
`
`
`A t
`
`
`
`220
`
`230
`
`y7 210
`
`PLASMA TREATMENT CHAMBER
`
`

`

`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 3 of 16
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`
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`

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`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 4 of 16
`20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 4 of 16
`Case 6
`
`U.S. Patent
`
`US 6,746,973 B1
`
`Sa“”=SLu4#--—-—--ON5i-—_——\——_>Zz>aLu2=|<-----=MNmwEO——>tgft:=2s=7QOvwaLu<«oOFJioe)OoFWo.“nN=n|=_j5YD=2ageNFk
`oO=\eWY)———_»xt
`mD.a»\Lua«+---co
`
`PLASMA
`TREATMENT
`COMPLEX
`
`PLASMA
`TREATMENT
`“=LuzOa=Oo
`oO
`
`% 275
`
`200
`
`270
`
`K_oOE2oO
`
`Oo
`
`REFLECTED
`PULSE
`RESPONSE
`
`240
`
`FIG. 2
`
`
`
`
`

`

`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 5 of 16
`20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 5 of 16
`Case 6
`
`U.S. Patent
`
`Jun.8, 2004
`
`Sheet 3 of 6
`
`US 6,746,973 B1
`
`oOOaoow©EZz©=
`
`Lu
`
`eeOaoe
`
`KNPRCeooiGogre
`
`SORCINIRTI
`
`FIG. 3
`
`

`

`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 6 of 16
`20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 6 of 16
`Case 6
`
`U.S. Patent
`
`Jun.8, 2004
`
`Sheet 4 of 6
`
`US 6,746,973 B1
`
`weeeeeeeeee
`
`500
`
`930
`
`onDOessseseieeeere
`
`FIG. 4
`
`FIG. 5
`
`
`
`
`
`

`

`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 7 of 16
`20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 7 of 16
`Case 6
`
`U.S. Patent
`
`Jun.8, 2004
`
`Sheet 5 of 6
`
`US 6,746,973 B1
`
`600
`
`PaaSShae
`
`RRRRY
`ESTieS
`
`650
`
`6
`
`620
`
`
`BORICOOOO
`BOOOOOOOOOOO
`
`2 2©
`
`rm
`2eSeS
`
`
`oSO
`4
`SMSO
`5dS05)50O
`ORS5
`SSeSC50)
`eset e:
`
`FIG. 6
`
`
`
`
`
`
`
`
`
`

`

`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 8 of 16
`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 8 of 16
`
`U.S. Patent
`
`Jun.8, 2004
`
`Sheet 6 of6
`
`US 6,746,973 B1
`
`START
`
`GENERAL
`INITIALIZATIONS
`
`710
`
`KO 700
`
`PREPARE WAFER
`
`720
`
`FORM LAYER
`
`730
`
`740
`
`795
`
`TREAT LAYER WITH
`FIRST PLASMA
`
`790|MONITOR TREATED
`ETCH LAYER THROUGH
`PHOTORESIST
`
`LAYER
`IS LAYER TREATED?
`
`FORM
`PHOTORESIST
`
`YES
`
`780
`
`770
`
`
`
`NO
`
`ADJUST FIRST PLASMA
`TREATMENT
`
`FIG. 7
`
`

`

`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 9 of 16
`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 9 of 16
`
`US 6,746,973 B1
`
`1
`EFFECT OF SUBSTRATE SURFACE
`TREATMENT ON 193 NM RESIST
`PROCESSING
`
`TECHNICAL FIELD
`
`2
`factors such as LER on chrome patterns residing on the
`reticle, image contrast in a system for generating the pho-
`toresist pattern, a plasma etch process which can be used to
`pattern the photoresist, natural properties of the photoresist
`materials, and the photoresist processing method.
`In addition, LER on a semiconductor feature can result
`from the radiation used to process a photoresist formed over
`an underlying layer. For example, thinner photoresist layers
`are typically utilized when forming smaller features having
`higher resolution. Thus, shorter wavelength radiation from
`193 nm and loweris employedto process these photoresists.
`However, photoresists processed with the shorter wave-
`length radiation experience damaging surface interactions
`with the underlying layer. That is, when irradiated with 193
`nm and lower radiation,
`the surface of the photoresist
`interacts with the surface of the underlying layer causing
`LER to occur on the developed photoresist.
`As the fabrication trend of semiconductors relies heavily
`on producing more miniaturized and more densely packed
`wafers, the use of photoresists using 193 nm and below
`radiation is substantially increasing in order to meet the
`demands of the industry. Undesirable surface interactions
`between the photoresist and the underlying layer appear to
`be more serious for 193 nm photoresists, which have less
`etch resistance than resists used at higher wavelengths such
`as 248 nm, 365 nm,etc. Because the photoresist material is
`relatively soft and thin when irradiated at
`this desired
`wavelength, the radiation used to pattern the photoresist may
`lithography refers to processes for pattern
`In general,
`undesirably affect the underlying layer. The condition may
`30
`transfer between various media. It is a technique used for
`even worsen for wavelengths below 193 nm, such as 157 nm
`integrated circuit fabrication in whichasilicon slice, the
`photoresists. Moreover, LER can interfere with accurate
`wafer, is coated uniformly with a radiation-sensitive film,
`metrology and adversely affect device performance.
`the photoresist, and an exposing source (such as optical
`With respect to FIG. 1, for example, forming 300 nm pitch
`light, X-rays, or an electron beam) illuminates selected areas
`trenches 20 in a photoresist layer 30 overlying a silicon
`of the surface through an intervening master template, the
`oxynitride 40 and a substrate 50 using 193 nm photoresist
`photoresist mask, for a particular pattern. The lithographic
`processing results in substantial LER 60 on the surfaces of
`coating is generally a radiation-sensitized coating suitable
`the trenches. In addition, signs of undesirable surface inter-
`for receiving a projected image of the subject pattern. Once
`action may be observed on the top surface 70 of the layer.
`the image is projected, it is indelibly formed in the coating.
`Conventional resolutions to these problems involve forming
`The projected image may beeither a negative or a positive
`an undoped oxide cap after the layer is formed but before
`of the subject pattern. Exposure of the coating through the
`photoresist deposition and processing begins. However, the
`photoresist mask causes a chemical transformation in the
`occurrences of the surface abnormalities and poor feature
`exposed areas of the coating thereby making the image area
`profiles persist despite the oxide cap.
`either more or less soluble (depending on the coating) in a
`particular solvent developer. The more soluble areas are
`removed in the developing process to leave the pattern
`image in the coating as less soluble polymer. Theresulting
`pattern image in the coating, or layer, may be at least one
`portion of a semiconductor device that contributes to the
`overall structure and function of the device.
`
`The present invention generally relates to processing a
`semiconductor substrate. In particular, the present invention
`relates to treating a surface of a virgin silicon oxynitride
`layer with an oxygen-nitrogen plasma to facilitate a reduc-
`tion in line edge roughness and surface interaction with
`respect to subsequent 193 nm and below photoresist pro-
`cessing.
`
`BACKGROUND ART
`
`Achieving the objectives of miniaturization and higher
`packing densities continue to drive the semiconductor manu-
`facturing industry toward improving semiconductor pro-
`cessing in every aspect of the fabrication process. Several
`factors and variables are involved in the fabrication process.
`For example, at
`least one and typically more than one
`photolithography process may be employed during the fab-
`rication of a semiconductor device. Each factor and variable
`
`implemented during fabrication must be considered and
`improved in order to achieve the higher packing densities
`and smaller, more precisely formed semiconductor struc-
`tures.
`
`10
`
`15
`
`20
`
`25
`
`35
`
`40
`
`45
`
`50
`
`Because the photoresist is used to form features on the
`semiconductor devices, the integrity of the photoresist must
`be maintained throughout the lithography process. That is,
`any flaw or structural defect which is present on the photo-
`resist may be indelibly transferred to underlying layers
`during a subsequent etch process wherein the photoresistis
`employed. However, protecting the integrity of the photo-
`resist layer may not always prevent the formation of flawed
`or defective semiconductor features on the wafer. Various
`other layers or attributes of the wafer may be the cause of
`undesirable structural defects.
`
`One example of an undesirable structural defect is line-
`edge roughness (LER), as seen on a wafer 10 in Prior Art
`FIG. 1. LERrefers to surface variations and irregularities
`particularly on the sidewalls of a feature, but also on the top
`and bottom perimeters of the feature. LER may originate
`with the photoresist layer which can be caused by various
`
`55
`
`60
`
`65
`
`SUMMARYOF THE INVENTION
`
`The following presents a simplified summary of the
`invention in order to provide a basic understanding of some
`aspects of the invention. This summaryis not an extensive
`overview of the invention. It is intended to neither identify
`key or critical elements of the invention nor delineate the
`scope of the invention. Its sole purpose is to present some
`concepts of the invention in a simplified form as a prelude
`to the more detailed description that is presented later.
`The present
`invention provides a novel system and
`method for mitigating the occurrence of surface abnormali-
`ties on etched semiconductor features caused by undesirable
`surface interaction between a surface of a layer and the
`photoresist formed thereon during a lithography process.
`More specifically, the present invention provides a system
`and method for reducing line edge roughness (LER) as it
`may occur on the surface of about 193 nm or lower photo-
`resists overlying a silicon oxynitride orsilicon nitride layer.
`This aspect of the present invention is accomplished in part
`by applying a plasma treatment onto the surface of the layer
`before a photoresist
`is formed thereon. In addition,
`the
`present invention is accomplished in part by employing a
`
`

`

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`US 6,746,973 B1
`
`10
`
`15
`
`BRIEF DESCRIPTION OF DRAWINGS
`
`FIG. 1 illustrates a schematic cross-section of a partially
`fabricated semiconductor device in accordance with the
`prior art.
`FIG. 2 illustrates a high-level, schematic block diagram of
`a semiconductorstructure in accordance with another aspect
`of the present invention.
`FIG. 3 illustrates a schematic cross-section of a semicon-
`
`20
`
`ductor structure in accordance with another aspect of the
`present invention.
`FIG. 4 illustrates a schematic cross-section of a semicon-
`
`3
`4
`is selective to the layer and which doesnotactas an etchant;
`monitoring device to oversee the plasma treatment and to
`a plasma chamberfor treating the layer with the plasma
`determine whether the plasma treatment has beeneffective.
`treatment; one or more plasma treatment components opera-
`For example, a virgin silicon oxynitride layer may
`tively coupled to the plasma treatment for administering the
`undergo a plasma treatment before a photoresist is formed
`plasma treatment; and a monitor processor operatively con-
`thereon and patterned. The layer may be exposedtoafirst
`nected to the chamber and the wafer for controlling the
`plasma containing oxygen and nitrogen followed by an
`plasma treatment and for determining whetherthe layer has
`optional second plasma containing nitrogen and hydrogen.
`been protected against surface abnormalities.
`The surface of the silicon oxynitride layer is treated with the
`first plasma in order protect
`it from undesirable effects
`caused by short wavelength photoresist processing.
`Examples of undesirable effects include surface interaction
`between the surface of the silicon oxynitride layer and the
`photoresist layer, resulting in LER on the developed photo-
`resist layer. The LER on the developed photoresist layer may
`be transferred to the underlying silicon oxynitride layer,
`thereby interfering with device formation and performance.
`The first plasma treatment containing oxygen and nitro-
`gen is not employed under conventional etch process con-
`ditions. Therefore, the plasma treatment does not substan-
`tially etch, remove, or damage in any way anyportion of the
`exposed silicon oxynitride layer or any other layer that may
`be exposed to the treatment. The first plasma treatment
`modifies the surface of the silicon oxynitride layer in such a
`mannerto prevent unwanted surface interaction arising from
`subsequent short wavelength photoresist processing. After
`the short wavelength photoresist is patterned, conventional
`etchants employed under etch process conditions may be
`utilized to selectively remove exposed portionsofthe silicon
`oxynitride layer as desired. Furthermore, a monitor proces-
`sor may be employed during the fabrication process to
`determine whether the plasma treatment has been
`administered,
`to adjust plasma treatment components as
`needed and to provide feedback information to a fabrication
`process and/or system as it relates to the status of the
`modified layer.
`Oneaspect of the present invention relates to a method for
`mitigating surface abnormalities on a semiconductor struc-
`ture. The method involves providing a semiconductor sub-
`strate having a layer formed thereon; exposing the layer to
`a plasma treatment in order to mitigate surface interactions
`between the layer and a subsequently formed photoresist
`without substantially etching the layer, the plasma contain-
`ing oxygen and nitrogen; forming a patterned photoresist
`layer over the treated layer; and etching the treated layer
`through one or more openings in the patterned photoresist
`layer.
`invention relates to a
`Another aspect of the present
`method for mitigating surface abnormalities in situ on a
`semiconductor structure. The method involves providing a
`semiconductor substrate having a virgin silicon oxynitride
`layer deposited thereon; exposing the silicon oxynitride
`layer to a plasma treatment in order to mitigate surface
`interactions between the silicon oxynitride layer and a
`subsequently formed photoresist without substantially etch-
`ing the silicon oxynitride layer, the plasma containing oxy-
`gen and nitrogen; determining whetherthe silicon oxynitride
`layer has been treated by employing a monitor processor;
`forming a patterned photoresist layer over the treated silicon
`oxynitride layer; and etching the treated silicon oxynitride
`layer through openingsof the patterned photoresist layer to
`form a semiconductor feature.
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`Yet another aspect of the present invention relates to a
`system for mitigating LER in situ during fabrication of a
`semiconductor structure. The system includes a layer con-
`taining silicon oxynitride, the layer being contained within
`a chamberand being exposedto a plasma treatment, which
`
`65
`
`ductor structure in accordance with an aspect of the present
`invention.
`FIG. 5 illustrates a schematic cross-section of a semicon-
`
`ductor structure in accordance with another aspect of the
`present invention.
`FIG. 6 illustrates a schematic cross-section of a semicon-
`
`ductor structure in accordance with another aspect of the
`present invention.
`FIG. 7 illustrates a schematic flow diagram of a method
`for mitigating the occurrence of LER and surface interaction
`in accordance with one aspect of the present invention.
`DISCLOSURE OF INVENTION
`
`The present invention involves a system and method for
`mitigating surface abnormalities on semiconductor devices,
`and on developed photoresists in particular, by exposing a
`virgin, or unprocessed, surface before a photoresist
`is
`formed thereon with a plasma. More specifically, the present
`invention facilitates reducing the occurrence of line edge
`roughness (LER) caused by damaging surface interactions
`between a surface of a 193 nm or lower photoresist and a
`surface of an underlying layer. Treating the underlying layer
`(or exposed layer of material) before a 193 nm or lower
`photoresist 1s formed over or directly on top of the treated
`layer substantially reduces,if not eliminates, the undesirable
`interactions between the surfaces of the photoresist and the
`layer which causes LER formation on the developed pho-
`toresist. Because this surface interaction is minimized or
`eliminated,
`the photoresist can be irradiated with short
`wavelength radiation from 193 nm and lower and devel-
`oped. As a result, the developed 193 nm or lowerphotoresist
`is substantially free of LER.
`The present invention is particularly applicable to virgin
`silicon oxynitride and silicon nitride layer surfaces where a
`photoresist
`is patterned thereon using short wavelength
`radiation which herein means about 193 nm or lower wave-
`
`length radiation. A virgin surface is a surface which has not
`been processed or exposed to an etchant, any other
`substance, or radiation. It should be understood that other
`types of layer materials are contemplated and are intended to
`fall within the scope of the present invention. Short wave-
`length radiation specifically includes about 193 nm light and
`about 157 nm light.
`Mitigating the occurrence of LER and/or surface interac-
`tions (e.g., between the surface of the layer to be etched and
`
`

`

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`US 6,746,973 B1
`
`5
`the surface of the photoresist used to etch the layer) on
`semiconductor devices may be accomplished in part by
`exposing a virgin silicon oxynitride or siliconnitride layer to
`a first plasma treatment containing oxygen (O.) and nitrogen
`(N,). An optional second plasmatreatment containing nitro-
`gen (N,) and hydrogen (H,) may follow the first plasma
`treatment. The first plasma treatment is administered under
`non-etch process conditions which means that it merely
`modifies the virgin layer at least at its surface in order to
`protect it from undesirable short wavelength photoresist
`processing effects such as LER. In particular, the first plasma
`treatment alters or hardens the surface of the layer without
`substantially etching, removing or damaging any portion of
`the layer or any other layer exposed to the first plasma.
`Furthermore, structural features are not destroyed or dam-
`aged in any waybythefirst plasma treatment.
`Following the first plasma treatment, a short wavelength
`photoresist may be formed over the layer and patterned. In
`particular,
`the short wavelength photoresist is selectively
`irradiated with about 193 nm or lower wavelength radiation
`and either the irradiated or non-irradiated portions are
`removed using a developer, thereby exposing a portion of
`the treated layer. Exposed portions of the treated layer may
`be etched through openings in the short wavelength photo-
`resist using suitable etchants under suitable etch process
`conditions. Because the layer is treated with the oxygen-
`nitrogen plasma, the photoresist layer which is subsequently
`formed thereonis protected from interacting with the surface
`ofthe (treated) layer during the short wavelength processing.
`Consequently, the developed photoresist is substantially free
`of surface abnormalities such as LER. Likewise, the features
`etchedin the treated layer can be substantially free of surface
`abnormalities as well. Moreover, feature profiles are sub-
`stantially improved. Examples of features include vias,
`trenches, dual damascenestructures, and the like.
`Because the plasma treatment reduces the amount or
`degree of surface interaction between the short wavelength
`photoresist and the layer, the top surfaces of the photoresist,
`and thus the treated layer, are also substantially free of
`surface abnormalities such as ridges, roughness, and the
`like.
`
`The first plasma contains a sufficient amount of oxygen
`and nitrogen to mitigate the occurrence of LER and/or
`surface interactions between a photoresist and an underlying
`layer. In one embodiment, the first plasma contains from
`about 94% to about 97% oxygen by volume and from about
`3% to about 6% nitrogen by volume.
`In another
`embodiment, the first plasma contains from about 95% to
`about 96% oxygen by volume and from about 4% to about
`5% nitrogen by volume. In someinstances, thefirst plasma
`may contain additional components, so long as the plasma
`continues to mitigate the occurrence of LER and/or surface
`interactions between the treated layer and an overlying
`photoresist
`layer.
`In yet another embodiment,
`the first
`plasma consists essentially of oxygen and nitrogen.
`Thefirst plasma treatment may be followed by an optional
`second plasma treatment. The second plasma contains a
`sufficient amount of nitrogen and hydrogen to further miti-
`gate the occurrence of LER and/or surface interactions. In
`one embodiment, the second plasma contains from about
`94% to about 98% nitrogen by volume and from about 2%
`to about 6% hydrogen by volume. In another embodiment,
`the second plasma contains from about 95% to about 97%
`nitrogen by volume and from about 3% to about 5% hydro-
`gen by volume. In some instances, the second plasma may
`contain additional components, so long as the plasma con-
`tinues to mitigate the occurrence of LER and/or surface
`
`10
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`15
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`20
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`25
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`35
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`60
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`65
`
`6
`interactions between the treated layer and an overlying
`photoresist layer. In yet another embodiment, the second
`plasmaconsists essentially of nitrogen and hydrogen.
`The first and second plasma treatments may be adminis-
`tered at a flow rate suitable to mitigate the occurrence of
`LER and/or surface interactions. In one embodiment, the
`first plasma treatment includes an oxygen flow rate from
`about 1500 sccm to about 2500 sccm and nitrogen flow rate
`from about 50 sccm to about 150 sccm.
`In another
`embodiment, the oxygen flow rate is from about 1750 sccm
`to about 2250 sccm and the nitrogen flow rate is from 75
`scem to about 125 sccm. In yet another embodiment, the
`oxygenflow rate is from about 1900 to about 2100 sccm and
`the nitrogen flow rate is from about 95 sccm to about 105
`sccm.
`
`The optional second plasma treatment containing nitrogen
`and hydrogen hasa flow rate from about 1800 sccm to about
`3000 sccm. In another embodiment,
`the optional second
`plasma flow rate is from about 2100 sccm to about 2700
`sccm.
`In yet another embodiment,
`the optional second
`plasma flow rates is from about 2300 sccm to about 2550
`sccm.
`
`In addition,the first and second plasmatreatments may be
`administered under a pressure to mitigate the occurrence of
`LER and/or surface interactions between the treated layer
`and an overlying photoresist layer undergoing processing
`and development. In one embodiment,the first and optional
`second plasma pressures are independently selected from
`about 600 mTorr
`to about 1800 mTorr.
`In another
`embodiment, the first and optional second plasmapressures
`are independently selected from about 950 mTorr to about
`1550 mTorr.
`In yet another embodiment,
`the first and
`optional second plasmapressures are independently selected
`from about 1050 mTorr to about 1350 mTorr.
`
`The temperature employed during the first and second
`plasma treatments may be any suitable temperature to miti-
`gate the occurrence of LER and/or surface interactions. In
`particular, during the first and optional second plasma
`treatments, the temperature in the treatment chamber can be
`set and/or regulated such that the wafer or substrate tem-
`perature is maintained from about 100° C. to about 300° C.
`The first and second plasma treatments may be adminis-
`tered for a time sufficient to mitigate the occurrence of LER
`and/or surface interactions. In one embodiment, the duration
`of the first plasma treatment is from about 100 to about 200
`seconds; and the duration of the optional second plasma
`treatment is from about 10 seconds to about 35 seconds. In
`
`another embodiment, the duration of the first plasmatreat-
`ment is from about 125 seconds to about 225 seconds; and
`the duration of the optional second plasmatreatmentis from
`about 15 seconds to about 30 seconds.
`In yet another
`embodiment, the duration of the first plasma treatment is
`from about 145 seconds to about 175 seconds; and the
`duration of the optional second plasma treatment is from
`about 18 seconds to about 25 seconds.
`
`Other process conditions may also be employed and are
`contemplated to fall within the scope of the present inven-
`tion.
`
`According to another aspect of the present invention, a
`monitor processor can be utilized to control thefirst plasma
`treatment and to determine whether a layer of material has
`been treated with the oxygen-nitrogen plasmabefore a short
`wavelength photoresist
`layer is formed and developed
`thereon. In particular, the monitor processor may be opera-
`tively connected to a plasma treatment chamber, a plasma
`treatment complex, plasma treatment components and to an
`
`

`

`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 12 of 16
`Case 6:20-cv-01216-ADA Document 41-14 Filed 10/06/21 Page 12 of 16
`
`US 6,746,973 B1
`
`7
`output device. The monitor processor is located such that it
`may transmit pulses (e.g., at least one pulse) to and receive
`reflected pulse responses (e.g., at least one reflected pulse)
`from the layer of material. The transmitted and reflected
`pulses may bein the form of light at a suitable wavelength
`and/or sound at a suitable frequency to carry out the present
`invention. The transmitted pulse and reflected pulse activity
`may be recorded by the monitor processor or some other
`data recorder internal or external to the monitor processor.
`Because the plasma treatment transformsat least the surface
`of the layer of material in some manner, a reflected pulse
`response from a treated layer exhibits a different appearance
`than a reflected pulse response from a non-treated layer.
`Thus, a user or programmed machine can differentiate
`between an oxygen-nitrogen treated layer and a non-treated
`layer by observing and analyzing the reflected pulse
`responses.
`In addition, the monitor processor operates to signal the
`plasma treatment to apply another treatment to the layer
`either under the same treatment parameters as the prior
`treatment or under amended parameters (e.g., flow rate of
`plasma, pressure,
`temperature, duration), adjustments to
`which can be controlled and implemented by the monitor
`processor. Likewise, the monitor processor can also termi-
`nate subsequent plasma treatments when it determines that
`the layer has been treated and therefore be moved on to the
`next stage in the fabrication process. Furthermore,
`the
`monitor processor provides feedback information to a fab-
`rication process and/or system as it relates to the current
`status (e.g., layer: not treated, treated; first plasma treatment:
`completed, not completed; and the like) of the layer. This
`allows the fabrication process or system to prepare for
`upcoming processing steps and to make process or system
`adjustments based on the current status of the layer.
`The plasma treatment complex may also instruct and/or
`control the plasma treatment components in order to activate
`or terminate the components depending on instructions
`and/or information provided by the monitor processor.
`Oncethe layer has beentreated, it can proceed to the next
`phase of fabrication where it may receive a short wavelength
`photoresist
`layer. The short wavelength photoresist may
`have a thickness from about 3000 angstroms to about 4500
`angstroms. The photoresist is subsequently irradiated using
`193 nm or lower radiation and developed accordingly to
`provide a patterned photoresist where portions of the plasma
`treated layer are exposed through the openings. Because the
`underlying layer was treated with the first and optional
`second plasma treatments, substantially no interaction
`occurred between the treated layer and the photoresist layer.
`Therefore, the features formed on the developed photoresist
`are substantially free of LER.
`During a subsequent etch process of the treated layer,
`selected portions of the treated layer may be exposed to an
`etchant through openings of the developed photoresist layer
`in order to transfer the semiconductor feature(s) onto the
`layer. Because the developed photoresist is substantially free
`of LER, the features transferred to the layer can also be
`substantially free of LER. Hence, the plasma treatment of
`the layer does not preclude the effectiveness and efficiency
`of conventional etchants.
`
`invention may be further described with
`The present
`respect to a silicon oxynitride layer undergoing a semicon-
`ductor process to form trenches having, for example, a 300
`nm pitch using a short wavelength photoresist layer formed
`over the silicon oxynitride layer, wherein the photoresist
`layer is patterned by 193 nm or lowerradiation for enhanced
`resolution of the feature, as illustrated in FIGS. 2—7 below.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`8
`FIG. 2 illustrates a high-level, schematic block diagram of
`a system 200 for mitigating the occurrence of LER during
`fabrication of a semiconductor device. The system 200
`includes a semiconductorstructure 210. The semiconductor
`structure 210 contains a silicon oxynitride layer 220. The
`layer 220, which also has an exposed top surface 230, may
`be described as a virgin layer 220 since it has not been
`subjected to any form of processing. Alternatively,
`the
`structure 210 may contain a silicon nitride layer.
`The semiconductor structure 210 may be housed within a
`plasma treatment chamber 240 in preparation of exposure to
`a first plasma treatment 275. The first plasma treatment
`contains about 95% oxygen by volume and about 5%
`nitrogen by volume. The first plasma treatment 275 is
`administered at an oxygen flow rate of about 2000 sccm, a
`nitrogen flow rate of about 100 sccm and undera pressure
`of about 1200 mTorr for about 150 seconds. Any suitable
`temperature may be employed to mitigate the occurrence of
`LER and/or surface abnormalities, such that the temperature
`of the structure 210 is maintained from about 100° C.
`to
`about 300° C.
`
`An optional second plasma treatment (not shown) con-
`taining about 96% nitrogen by volume and about 4% hydro-
`gen by volume may be administered after the first plasma
`treatment and before forming a patterned photoresist thereon
`at process conditions similar to the first plasma treatment.
`For example, the optional second plasma may be adminis-
`tered at a combinedflow rate of about 2500 sccm and under
`
`a pressure of about 1200 mTorr. The second plasmatreat-
`ment may be about a 20 second process and at any tem-
`perature suitable to mitigate the occurrence of LER and/or
`surface abnormalities.
`
`The plasma treatment chamber 240 maybe an integral
`part of a main processing chamber used during semicon-
`ductor processin