WO2009088357A1 - Procédé pour couches de structuration de surface par procédé lift-off sur un substrat - Google Patents

Procédé pour couches de structuration de surface par procédé lift-off sur un substrat Download PDF

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Publication number
WO2009088357A1
WO2009088357A1 PCT/SG2008/000003 SG2008000003W WO2009088357A1 WO 2009088357 A1 WO2009088357 A1 WO 2009088357A1 SG 2008000003 W SG2008000003 W SG 2008000003W WO 2009088357 A1 WO2009088357 A1 WO 2009088357A1
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WIPO (PCT)
Prior art keywords
layer
resist
film
adhesion
substrate
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Ceased
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PCT/SG2008/000003
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English (en)
Inventor
Nagarajan Ranganathan
Ebin Liao
Wen Sheng Vincent Lee
Rakesh Kumar
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Agency for Science Technology and Research Singapore
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Agency for Science Technology and Research Singapore
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Priority to PCT/SG2008/000003 priority Critical patent/WO2009088357A1/fr
Publication of WO2009088357A1 publication Critical patent/WO2009088357A1/fr
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/26—Processing photosensitive materials; Apparatus therefor
    • G03F7/40—Treatment after imagewise removal, e.g. baking
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P50/00—Etching of wafers, substrates or parts of devices
    • H10P50/20—Dry etching; Plasma etching; Reactive-ion etching
    • H10P50/28—Dry etching; Plasma etching; Reactive-ion etching of insulating materials
    • H10P50/286—Dry etching; Plasma etching; Reactive-ion etching of insulating materials of organic materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
    • H10P76/00—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography
    • H10P76/20—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising organic materials
    • H10P76/202—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising organic materials for lift-off processes

Definitions

  • This invention relates generally to the field of semiconductor manufacturing, and more particularly to a method and apparatus for lift-off patterning films on a semiconductor.
  • a patterned conductor layer may be formed on a substrate by various methods well known in the field of electronic device fabrication.
  • Subtractive etching is one common method.
  • subtractive etching after a blanket film is deposited on the substrate, the film is etched through a photoresist mask in order to remove undesired portions.
  • Such process however suffers from a number of disadvantages that restrict their application, particularly in the patterning of noble metals which are difficult to etch.
  • the deposited metal has to be chemically reactive and volatile.
  • Lift-off techniques or additive metallization is an alternative method used to overcome the above-mentioned issues in patterning of difficult metal films or metal stacks on a processed semiconductor substrate.
  • One approach involves coating a photo resist layer on a substrate, and then patterning the layer through a photo mask. A metal layer is then formed on the patterned photo resist, which is subsequently lifted-off, taking with it the undesired portions of the metal layer.
  • FIGS. 1A-1D is an Illustration of a typical additive metallization or lift-off metallization process
  • a lift-off technique is commonly employed to selectively or additively pattern metals which are normally difficult to etch such as Gold (Au), Platinum (Pt) and metal stacks such as under-bump metallization and solder for packaging applications. While patterning etchable metals or metal stacks by photolithography and etching on planar surfaces is trivial, doing so over topographies tens of microns in height is quite difficult. The patterning of metals along steep sidewalls and drilled holes is extremely difficult with conventional photoresist and lithographic processes. The steep sides make it virtually impossible to get good step coverage with spin coated photoresist.
  • a challenge faced in conventional lift-off methods is that ultrasonic, LN 2 or CO 2 spray cleaning is not sufficient to remove the sidewall metal filaments that may occur as a result of the process, which is shown in FIG. 1C.
  • Metals deposited on sidewalls and the foot of the resist mask causes residues in the edges of the metal patterns which are difficult to remove. Due to metal deposition on resist sidewalls, especially for thick resist/metal films, the metal on the sidewall remains as a filament, which may short the adjacent patterns. Re-deposition of metal contamination into deep grooves during metal strip is another common issue. Metal residues increase when thicker films are deposited. Etching is not preferred due to multiple metallization patterns.
  • United States Patent No. 5,554,488 discloses a method of performing lift-off metallization by taking advantage of weak adhesion between SiO 2 and Si 3 N 4 films with arsenic oxide in a GaAs substrate in fabricating high temperature metallization for fabrication of FETs in GaAs substrates. After patterning an inorganic hard mask like SiO 2 and Si 3 N 4 , the required metal is deposited and later the unwanted metal and hard mask is removed by attaching an adhesive tape and delaminating the unwanted metal along with the hard mask. The dielectric mask and unwanted metal is peeled from the weak adhesion region.
  • the process is suitable only for patterning on planar surfaces. Not suitable for implementing on highly uneven topographies as in MEMS and Optical sub-assembly applications. Additionally, the method is suitable only for compound semiconductor substrates like GaAs where the surface oxide has poor adhesion with SiO 2 and Si 3 N 4 films which are used as high-temperature hard mask. The method also needs multilayered hard mask and sidewall undercut.
  • United States Patent No. 5,209,815 discloses another way of performing lift-off process by using a sacrificial release layer made of polyether sulfide polymer followed by multiple layers of organic resist coatings to form a reentrant sidewall profile to facilitate a breakage of deposited metal at the mask sidewall.
  • the unwanted metals and resist mask is removed by using an adhesive tape as in previous prior art.
  • the sacrificial polyether sulfone layer is first chemically etched before using the adhesive to peel-off the metal/resist mask.
  • This approach also has limitations, such as, suitable only for planar surfaces. Not suitable for implementing on highly uneven topographies as in MEMS and Optical sub-assembly applications.
  • the polyether sulfone release layer and photoresist has to be coated on the substrate before the lift-off process and hence is highly unsuitable for MEMS and Optical MEMS application due to uneven topography. Additionally, the metal and the resist layers can be peeled-off only if the release layer is fully removed. Removal of release layer is highly design dependent and hence cannot be implemented for dark field type of masks which have large areas covered with photoresist.
  • An aspect of the invention provides a method of forming a patterned film of a first material on a semiconductor substrate comprising providing a semiconductor substrate having a surface; patterning the surface of the substrate with a resist layer forming a mask on surface of the substrate with a predefined pattern; depositing the first material on the patterned resist layer; applying a removal material on the first material, the first material and the resist layer sharing weakly bonded characteristics with one another, the adhesion between the resist layer to the first material is less than the adhesion of the first material to the removal material; and removing the removal material resulting in removal of the unwanted portions of the first material from the resist material, leaving the patterned film of the first material on the substrate.
  • This is possible due to stronger bond between the first material and the substrate while the bond between the first material and the removal material is relatively weaker in the areas where the removal material makes contact with first material.
  • An embodiment of the invention further comprises removing the resist layer from the surface of the substrate leaving the semiconductor device on the surface of the substrate.
  • the surface of the substrate may be non-planar.
  • the first material may be a conductive material such as a metal or a noble metal.
  • the first material may also be an insulating material or a dielectric material or a combination of conductive and insulating materials.
  • At least one additional layer may be formed over the first material by patterning the surface of the first material with a resist layer forming a mask on surface of the substrate with a predefined pattern; depositing the additional material on the patterned resist layer; the additional material to form a top layer, where the removal material is applied to the top layer, and the top layer and the resist layer share weakly bonded characteristics with one another while the top layer and the first material share a stronger bond. In this way, the adhesion between the resist layer to the top layer is less than the adhesion of the top material to the first material and the adhesion of the top layer to the removal material.
  • the additional layer may be a metal.
  • the additional materials may comprise depositing a plurality of additional layers on the first material layer to form a composite stack of layers, where the upper most layer of the plurality of additional layers forms the top layer, and the adhesion between the resist material and the top layer is less than the adhesion between each adjacent additional layer in the composite stack of layers.
  • the composite stack may comprise different metal layers.
  • the resist layer is an organic layer, a dry resist film and may form a photo resist mask.
  • the patterning of the resist layer may comprise re-entrant and/or straight walled profiles.
  • the patterning and removal lift-off material process of embodiments of the invention may be applied at different layers of the process as well as the surface of the substrate.
  • the removal of the material comprising the first material or the top layer comprises fracturing the first material or the top layer at the edge of the pattern defined by the photo-resist mask. Applying and removing the removal material comprises laminating and delaminating a polymer film.
  • the substrate may be heated to create a mismatch between the resist layer and the first material or the top layer material. Removal of the resist layer comprises bonding a polymer film with an adhesion strength to the resist layer greater than the adhesion strength of the resist layer to the substrate layer with an adhesive, UV tape, or the like.
  • the organic layer is a dry resist film lithography, a spin-coated photo resist mask, or a low-adhesion photo definable polymer.
  • the organic layer can also be a low-adhesion etchable polymer mask.
  • the removal of the unwanted deposited material comprises removing the material from the top surface and sidewalls of the patterned organic masking layer by laminating an adhesive film and then delaminating selectively the unwanted material.
  • the lamination process comprises bonding an adhesive polymer film with an adhesion strength to the deposited material greater than the adhesion strength of the deposited material with the organic masking layer.
  • the method of removal of unwanted material from the organic masking layer may optionally comprise heating the substrate to create a mismatch between the organic layer and the deposited layer and then delaminate the unwanted material from the organic masking layer easily.
  • the removing of the organic layer from the substrate further comprises laminating and later delaminating a polymer film with an adhesion strength to the organic layer greater than the adhesion strength of the organic layer with the substrate layer.
  • the deposited metal film or film stack have a weak adhesion interface between metal and the masking layer.
  • the weak adhesion layer which promotes the delamination of unwanted metal is on the top of the masking layer. Due to the weak- adhesion interface on the top of the masking layer allows delamination of metal and masking layers separately. As a consequence, the unwanted metal film is effectively stripped or delaminated before the mask removal process, and the final mask removal process therefore may not contribute any metallic contamination or reliability issues.
  • the polymer film is bonded to the entire surface during the lamination process, due to a stronger bond between the deposited material and the substrate compared to bond between the deposited film and the polymer film, the pattern formed by the deposited material remains intact on the substrate. Only the deposited material over the masking material is removed.
  • FIGS. 1A-1C illustrates a conventional additive metallization or lift-off metallization process in accordance with an embodiment of the invention
  • FIG. 2 is a flow chart of a method in accordance with an embodiment of the invention.
  • FIGS. 3A-3G illustrates the method of FIG. 2 in process steps in accordance with an embodiment of the invention
  • FIG. 4 is a flow chart of a method in accordance with an embodiment of the invention.
  • FIGS. 5A-5E illustrates the method of FIG. 4 in process steps in accordance with an embodiment of the invention
  • FIG. 6 is a flow chart of a method in accordance with an embodiment of the invention.
  • FIGS. 7A-7E illustrates the method of FIG.6 in process steps in accordance with an embodiment of the invention
  • FIG. 8 is a flow chart of a method in accordance with an embodiment of the invention.
  • FIGS. 9A-9E illustrates the method of FIG. 8 in process steps in accordance with an embodiment of the invention
  • FIGS. 10A-10B shows pictures comparing the results of a prior art method (FIG. 10A) with a method (FIG. 10B) in accordance with an embodiment of the invention.
  • FIGS. 11A-11B show SEM images of cross-sectional views of dry film structure after lithography and after metal is deposited over resist in accordance with an embodiment of the invention.
  • a method of performing lift-off patterning process involves dry resist film lithography and deposition of metal or insulating film or combination of the both films followed by lamination with UV sensitive or equivalent adhesive film and then delaminating the top layer of thin film due to weak adhesion of deposited metal with the underlying organic layer.
  • the UV tape or UV sensitive adhesive film used refers to a class of organic film which displays strong adhesion when laminated to any surface under normal light but shows very low adhesion when exposed to a broadband UV light.
  • the unwanted dry resist film is stripped or peeled-off by again laminating a fresh layer of UV sensitive film and delaminating the unwanted dry resist film mask.
  • a feature of this technology is that it does not require any strong ultrasonic or mega sonic energy or thermal shock to break the adhesion of the film from the organic mask before stripping the metal or insulating film or combination of the both films and the organic mask.
  • Another feature of an embodiment of the invention is that it does not require a highly reentrant mask profile or multiple layers to create undercut mask profile.
  • the sputtered or evaporated films are usually non-conformal, the thin and weakly adhered sidewall metal films easily gets delaminated by the adhesive polymer film during the delamination process and thus resulting in smooth edges for the lift-off patterns.
  • a method of performing dry resist film lift-off patterning by the process of polymer film lamination and delamination process is disclosed.
  • An embodiment may involve high temperature film deposition by using a high-temperature sacrificial mask layer.
  • An embodiment may involve selective removal of metal or insulating film or combination of the both films and polymer masking layers by the lamination and delamination process.
  • An embodiment may use UV/IR radiation to cause delamination of metal or insulating film or combination of the both films from the polymer mask by local heating to cause CTE (coefficient of thermal expansion) mismatch and delaminate easily.
  • a lift-off mask is formed preferably by dry resist film but not limited only to dry resist film.
  • the material or material stack deposited on the resist film layer material may be any material difficult to etch under conventional processes.
  • the material may be difficult to etch because the material is a noble metal and is inherently difficult to etch due to properties of noble metals.
  • metal stacks comprised of composite layers of metals may be difficult to selectively etch.
  • Also difficult to etch is any material, which may not necessarily be a metal or noble metal, that is deposited or applied on non- planar substrate.
  • the lift-off material may be metallic or insulating type.
  • Metal or metal stack is deposited by e-beam evaporation, sputtering or by any other technique to selectively adhere to the required region where the metal patterns are required.
  • the substrate may be any substrate such as for example silicon substrate, glass substrate, or the like.
  • the whole metallized wafer is then laminated with UV tape or equivalent strong adhesive tape and then the unwanted metal is delaminated selectively from the organic masking layer.
  • the delamination process results in peeling the metals from the unwanted areas due to poor adhesion of metals on the surface of the mask.
  • a normal spin-coated, spray coated, electroplated photo resist or dry resist films can be used as a lift-off mask.
  • a masking process has been described which is suitable for doing higher temperature (300-400 0 C) material patterning by lift-off process.
  • the material that is patterned by lift-off can be any material or material stack that is difficult to etch as described above such as noble metals, gold (Au), copper (Cu), chromium (Cr), platinum (Pt), gold (Au), and metal stacks such as under-bump metallization and solder for packaging applications, and the like.
  • the solder film may be Au/Sn solder film, deposited in the range of sub-micron to 10 ⁇ m.
  • Metallization thickness 162 can vary from sub-micron to several microns.
  • the organic layer or dry resist film mask may have a thickness 160, for example, in the range of 20 ⁇ m, and a metal deposition, for example Ti/Pt/Au, may be in the range of 0.1 ⁇ m, 0.2 ⁇ m and 1.0 ⁇ m, respectively, as shown in FIG. 11B.
  • FIGS. 11A- 11 B shows SEM images of cross-sectional views of dry film structure after lithography and after metal of 1000A Ti/10,000A Au metal stack, as shown in FIG. 11 A, patterned by lift-off is deposited over resist in accordance with an embodiment of the invention.
  • An embodiment of the method of performing lift-off patterning process involves dry resist film or normal lithography and material deposition process followed by lamination with UV sensitive or equivalent adhesive film and then delaminating the top layer of thin film due to weak adhesion of deposited material with the underlying organic layer.
  • the unwanted dry resist film is stripped or peeled-off by again laminating a fresh layer of UV sensitive film and delaminating the unwanted dry resist film mask.
  • the thin and weakly adhered sidewall metal films easily gets delaminated by the polymer film during the delamination process and thus resulting in smooth edges for the metal patterns.
  • Embodiments of the invention disclosure relates to a process for forming a pattern of conductive material on a substrate for forming patterns of metallization for wide range of applications, for example, low to high-temperature metal or metal stack deposition, nano to micro-structures formation, for defining metal patterns on copper low-k wafers and on MEMS and optical sub-assembly wafers with deep cavities and grooves.
  • the method 10 shown in FIG. 2 comprises a dry resist film 32 lithography 12 and film deposition processes 14 for deposition of the lift-off layer 36 are performed followed by lamination 18 with UV sensitive or equivalent adhesive film 38 to bond with the deposited material film/stack layer and delaminating 19 to remove the top layer of unwanted deposited material film due to weak adhesion with the underlying organic layer.
  • the resist material 32 may be any type of lithography, for example dry resist film lithography, organic layer, dry resist layer, positive photoresist lithography, negative photo-resist lithography, electron beam (EB) lithography, and the like.
  • the lighography has a re-entrant profile 34.
  • the device wafer is patterned with the dry-resist film.
  • the first material layer 36 or lift-off material in this embodiment is a metal or insulating material or combination of both layers that may be deposited by deposition techniques such as evaporation, sputtering, and the like of desired material, metal film, metal stack or the like as required.
  • the lift-off material film 36 may be metallic as described in this embodiment, or another material such as an insulating material type material.
  • the thickness of first material 36 may range for example from a few nanometers to a few hundreds of nanometers.
  • the substrate may optionally be heated 16 too, for example to any suitable temperature between 100 0 C and the maximum reflow temperature of the masking layer, to create a CTE mismatch between the lift-off material and dry resist masking layer. It may further be noted that the selection of this optional heating step depends on the maximum temperature the lift-off material 36 and the masking layer can withstand.
  • another polymer film 40 with appropriate adhesion strength which may be stronger can be applied 20 and delaminated to strip-off 22 the sacrificial dry resist film mask. In FIG.
  • UV tapes or adhesives 38,40 that may be used include E8320 from Lintec Advanced Technologies, Inc. of Tokyo, Japan; SP-series UV tapes from Furukawa Electric Co. Ltd. of Tokyo, Japan; DT and GT-series UV tapes from Semiconductror Tapes and Materials, Inc.
  • a feature of this technology is that it does not require any chemical etch step to break or fracture the metal continuity 39 in the mask sidewalk It also does not require any organic release polymer like Polyether Sulfone to facilitate delamination of unwanted metals on the photo resist mask.
  • dry resist film being usually greater than 20 ⁇ m and also being a negative resist, it gives a good reentrant mask profile. Hence, it does not require multiple resist layers to make the profile reentrant for lift-off.
  • both the metal and dry resist film can be delaminated effectively by using UV films or equally strong adhesive film.
  • the dry resist film based lift-off process is suitable for patterning metals/metal stacks over large grooves and uneven topographies which is peculiar to MEMS, wafer level packaging and optical sub-assembly application.
  • a wide range of polymer films are available with wide choice of adhesion strength with various films to choose from.
  • Automated systems are also available to attach and detach the polymer tape from the wafer surface, i.e. automatic taping and de-taping tools are available.
  • FIG. 3G the final clean pattern 42 formed after bond and peel process is shown.
  • the lamination and delamination process is alternatively referred to as bond and peel process.
  • FIG. 4 An overview of an embodiment with lift-off process with spin-coated, spray-coated, electroplated, or the like photo resist mask is shown in method 50 of FIG. 4 and FIGS. 5A-5E.
  • this embodiment can be used as a variant of another embodiment.
  • a normal spin-coated or other type of photo resist masks 32 can be used (step 52) before performing the lift-off patterning process 54, applying a UV sensitive adhesive film 64 (step 56) with strong adhesive film with material film 36, that has a stronger adhesion than the adhesion between the material 36 and the resist material 32, and delaminate 57 the unwanted material 36 from the mask surface, for example delaminate weakly bonded metal/metal stack or insulating film/film stack on the resist mask.
  • the layer of unwanted material film 36 easily debonds 57 due to weak adhesion with the underlying organic layer 32.
  • the device wafers are patterned with photo-resist lithography 32 with re-entrant profile 34 for lift-off process as shown in FIG. 5A, where the deposition 54 of lift-off 36 material such as metal by evaporation, sputtering or the like of metal film or metal stack as required as shown in FIG. 5B.
  • Laminate 56 the lift-off with UV sensitive polymer film or equivalent strong adhesive film and delaminate 57 the weakly bonded metal films attached to the resist. Removal 58,60, as shown in FIG.
  • 5C and 5D of unwanted metal by bond and peeling-off with, for example polymer tape 64 may be followed by resist mask removal by stripper.
  • the continuity material 68 is removed as shown in FIG. 5D together with the lift-off material 36 and the delamination tool 64.
  • FIG. 5E the final clean pattern 66 formed after bond and peel process is shown.
  • FIG. 6 and FIGS. 7A-7E Another embodiment concerns selective removal of lift-off material over high temperature mask, as shown in the method 70 of FIG. 6 and FIGS. 7A-7E.
  • any standard high temperature inorganic films like silicon oxide or silicon nitride followed is deposited 72, such as by coating or deposition of a suitable organic film such as, for example, a low-k dielectrics which are known to have poor adhesion strength with metals and insulating materials like silicon dioxide and silicon nitride films.
  • the low- adhesion strength polymer and the hard mask are patterned by standard lithography and etch process to create features for lift-off materials.
  • a deposition process 74 is then performed followed by lamination with UV sensitive film or equivalent adhesive film.
  • the film is then delaminated 78 to remove the unwanted material film from the weak adhesion interface with the underlying organic layer.
  • the weakly bonded organic layer can be removed easily by means of lamination and delamination with the UV sensitive adhesive film or any film with equivalent strength.
  • the UV sensitive adhesive film or equivalent film can be used to delaminate or strip-off the sacrificial low- adhesion organic layer on the hard mask.
  • the low-adhesion polymer can be any high temperature lift-off polymer like PiRL-III supplied by Brewer Science Inc.
  • a polymer such as PiRL-III can withstand up to 300 degrees Celsius (300 0 C).
  • This embodiment is similar to a previous embodiment in many ways except for adding a low-adhesion polymer film over the mask to cause the lift-off metal to delaminate easily.
  • the device wafers are patterned 72 with low adhesion strength film 86 over hard mask 94 organic layers to create features for lift-off metallization 74, as shown in FIG. 7A and 7B where the deposit and pattern a stack of high-stress film 86 and hard mask layer, for example, SiO 2 , having a suitable edge profile 84 for deposition of lift-off material 36, such as a metal.
  • the edge profile 84 used for lift-off may be in the range of 80 to 90 degrees depending on the type of masking material used.
  • the low adhesion strength film or high stress film 86 may be for example plasma deposited amorphous silicon and plasma deposited fluorocarbon films. If necessary, the SiO 2 can be recessed or wet etched to assist in the lift-off process.
  • the deposit and pattern of low-adhesion film 72 may be any films which have poor adhesive strength with inorganic hard mask and metal films such as for example TEFLON-like films made of fluoro-carbons like C 4 F 8 , CHF 3 , CF 4 , C 3 F 8 , and the like. Thickness of the films 72 may range for example from 10 nanometers to a few hundred nanometers.
  • TEFLON is a trademark registered by E. I.
  • the substrate may optionally be heated 76 to, for example to any temperature between 100 0 C and the maximum reflow temperature of the organic masking layer, to create a CTE mismatch between the metal and masking layer. It may further be noted that the selection of this optional heating step depends on the maximum temperature the metal and masking layer can withstand.
  • Laminate and delaminate 78 the lift-off metal with suitable UV sensitive polymer film or equivalent to peal the weakly bonded metal on the low- adhesion strength film, as shown in FIG. 7C.
  • the sacrificial low-adhesion strength film is removed by bond and peeling-off with for example with UV sensitive polymer tape or any other adhesive film with suitable adhesive strength.
  • the continuity material 96 is removed as shown in FIG. 7D together with the lift-off material 36 and the delamination tool 88.
  • the hard mask can finally be removed 80 by for example plasma etching or selective chemical strip, as shown in FIG. 7D. It may be noted that metal and high- stress film delaminates due to weak adhesion. Removal 82 of any adhesive on wafer surface may be performed with resist strip to yield the final clean pattern 90 formed after bond and peel process is shown in FIG. 7E.
  • FIG. 8 and FIG. 9A-E An overview of an embodiment with selective removal of lift-off metal over high- temperature mask is shown in the method 100 of FIG. 8 and FIG. 9A-E.
  • This embodiment is a slight variation of another embodiment such that a high temperature organic lift-off mask 120 is used instead of the inorganic hard mask like silicon oxide or silicon nitride.
  • the organic mask can be any of the lift-off polymer which serves the dual pu ⁇ ose of acting as a lift-off mask and also as a low-adhesion polymer layer which facilitates easy removal of unwanted material from the surface of the lift-off mask.
  • the low-adhesion polymer can be photo definable or etchable polymer.
  • the weakly bonded organic layer can be removed easily by means of lamination and delamination with the UV sensitive adhesive film or any film with equivalent strength.
  • the UV sensitive adhesive film or equivalent film can be used to delaminate or strip-off the sacrificial low-adhesion organic layer on the hard mask.
  • the low-adhesion polymer can be any high temperature lift-off polymer such as PiRL-III supplied by Brewer Science Inc., and the like.
  • Some polymers that bond well with metals and inorganic dielectric materials like silicon dioxide and silicon nitride include, for example, polyimide from E. I. du Pont de Nemours and Company or BCB from The Dow Chemical Company.
  • a polymer such as PiRL-III can withstand up to 300 degrees Celsius (300 0 C).
  • the polymer film in the range of 5 ⁇ m may be deposited.
  • the high temperature polymer film may be deposited and pattern formed 102 to create the features of the liftoff patterns of high-temperature metal/insulating film or stack as required over the wafer may be evaporated or sputtered 104, as shown in FIG. 9A and 9B.
  • the high- temperature film may be PiRL polymer from Brewer Science which is specially designed for high temperature applications, and has poor adhesion to metals and insulators like silicon dioxide and silicon nitride.
  • the lift-off material 36 may be a metal film or metal stack as described in this embodiment and may be any metal such as Au, Cr, Ti, Pt and the like. In another embodiment the lift-off material may not be a metal, and may be a dielectric material or an insulator material, for example SiO 2 , Si x N y , and the like.
  • the liftoff material may be composite film stacks, for example Ti/Pt/Au which is used for under- bump metallization before solder bumping. The thickness of the film or film stack may vary for example from a few nanometers to a few hundreds of nanometers depending on the application.
  • a polymer film is laminated 106 and delaminated to peel the weakly bonded metal 116, and removal 108 of unwanted metal by bond and peeling-off with, for example, polymer tape 112,114, as shown in FIG. 9C and 9D.
  • the continuity material 122 is removed as shown in FIG. 9D together with the lift-off material 116 and the delamination tool 114.
  • the metal 116 breaks in the sidewall due to poor step coverage.
  • the polymer mask can be removed 108 by the lamination and delamination process with UV sensitive polymer tape or any other adhesive film with suitable adhesive strength or by plasma etching or selective chemical strip.
  • any adhesive residue on the wafer surface may be removed 110, for example by resist strip process, to yield the final clean pattern 118 formed after the bond and peel process, as shown in FIG. 9E.
  • FIG. 10A-B shows Ti/Au metal stack patterned by conventional lift-off 5 by using ultrasonic metal/resist removal showing unclean edges 7 as shown in FIG.
  • the deposited material film or film stack have a weak adhesion interface between the deposited material film/film stack and the masking layer.
  • the same method of lamination and delamination is used to strip or remove the sacrificial weak-adhesion material.
  • a weak-adhesion layer which promotes the delamination of unwanted metal is on the top of the masking layer unlike in previous attempts made in the prior art wherein the weak-adhesion layers are below the masking layers.
  • Embodiments of the invention make use of weak bonding of dry-film resist to the substrate. Mechanical peeling or delamination may be employed which causes the poorly adhered sidewall metals to break from the edges easily resulting in good patterns.
  • a dry-film, low-adhesion strength lift-off polymer, or the like may be used which shows poor adhesion with metal layers which does not require an additional weakening process, for example by chemical treatment or the like, to weaken the interface between the metal and the mask materials.
  • a UV release film, adhesive film or the like may be used to peel-off the metal and the dry-film resist without weakening the interface, such as be chemical treatment or the like.
  • Embodiments of the invention are suited for both planar and highly uneven topographies as in MEMS, optical sub-assembly applications, and the like.
  • Embodiments may be used for depositing at many different temperatures, such as for example ambient temperature, room temperature, and high temperatures such as high temperature metals, for example 300-400 0 C, and the like. It will be appreciated that the lift-off of embodiments of the invention is applicable for both inorganic and organic dry resist film mask. Embodiments of the invention reduce the risk of pattern damage due to re-deposition of metal and resist residues during the photoresist strip and clean processes, minimizing overhanging films in the edge of the transferred patterns by lift-off, or the use of aggressive cleaning methods like ultrasonic, LN 2 or CO 2 spray cleaning. Additionally, since these aggressive cleaning methods are not required in an embodiment of the invention, the method reduces the costs of post- deposition clean.
  • temperatures such as for example ambient temperature, room temperature, and high temperatures such as high temperature metals, for example 300-400 0 C, and the like.
  • the lift-off of embodiments of the invention is applicable for both inorganic and organic dry resist film mask.
  • Embodiments of the invention

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
  • Drying Of Semiconductors (AREA)

Abstract

La présente information concerne un procédé permettant de réaliser un traitement de structuration de surface par procédé lift-off, mettant en œuvre une couche de résiste sec ou une lithographie et un traitement de dépôt de matière suivi du laminage d'une couche adhésive sensible aux UV ou équivalent, puis du délaminage de l'épaisseur supérieure de la couche mince en profitant de la faible adhésion de la matière déposé par rapport à la couche organique sous-jacente. Dans un mode de réalisation, la couche de résiste sec à ne pas conserver est décollée par un nouveau laminage d'une épaisseur fraîche de couche sensible aux UV puis du délaminage du masque de la couche de résiste sec à ne pas conserver. Étant donné que les couches de pulvérisation ou d'évaporation ne sont généralement pas capables de conformation, les couches de métal des parois latérales faiblement collées sont facilement délaminées par la couche polymère pendant le traitement de délaminage, d'où des bords lisses pour les structurations métalliques.
PCT/SG2008/000003 2008-01-07 2008-01-07 Procédé pour couches de structuration de surface par procédé lift-off sur un substrat Ceased WO2009088357A1 (fr)

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ITMI20101890A1 (it) * 2010-10-15 2012-04-16 Microcontrol Electronic Srl Procedimento ed apparecchiatura per la rimozione di metallizzazioni su un substrato quale un wafer.
CN104217927A (zh) * 2014-09-29 2014-12-17 圆融光电科技有限公司 多层绝缘薄膜的图形化方法及芯片的多层绝缘薄膜
CN109781617A (zh) * 2019-01-17 2019-05-21 威士达半导体科技(张家港)有限公司 一种uv划片膜与底膜易撕效果的评估方法
CN110891895A (zh) * 2017-05-03 2020-03-17 纳米技术安全集团 通过选择性模板移除来进行微米和纳米制造的方法
CN113050391A (zh) * 2021-03-18 2021-06-29 歌尔股份有限公司 涂覆有uv胶的元器件的回收方法
US11261085B2 (en) 2017-05-03 2022-03-01 Nanotech Security Corp. Methods for micro and nano fabrication by selective template removal
TWI844798B (zh) * 2021-09-24 2024-06-11 頎邦科技股份有限公司 光阻剝離方法
US20250022820A1 (en) * 2023-07-10 2025-01-16 Stmicroelectronics International N.V. Under-bump metallization structures and associated methods of formation

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITMI20101890A1 (it) * 2010-10-15 2012-04-16 Microcontrol Electronic Srl Procedimento ed apparecchiatura per la rimozione di metallizzazioni su un substrato quale un wafer.
CN104217927A (zh) * 2014-09-29 2014-12-17 圆融光电科技有限公司 多层绝缘薄膜的图形化方法及芯片的多层绝缘薄膜
CN110891895A (zh) * 2017-05-03 2020-03-17 纳米技术安全集团 通过选择性模板移除来进行微米和纳米制造的方法
EP3619160A4 (fr) * 2017-05-03 2021-01-20 Nanotech Security Corp. Procédés de micro et nano-fabrication par élimination sélective de gabarit
US11261085B2 (en) 2017-05-03 2022-03-01 Nanotech Security Corp. Methods for micro and nano fabrication by selective template removal
CN109781617A (zh) * 2019-01-17 2019-05-21 威士达半导体科技(张家港)有限公司 一种uv划片膜与底膜易撕效果的评估方法
CN113050391A (zh) * 2021-03-18 2021-06-29 歌尔股份有限公司 涂覆有uv胶的元器件的回收方法
TWI844798B (zh) * 2021-09-24 2024-06-11 頎邦科技股份有限公司 光阻剝離方法
US20250022820A1 (en) * 2023-07-10 2025-01-16 Stmicroelectronics International N.V. Under-bump metallization structures and associated methods of formation

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