US20010033634A1 - High contrast ratio membrane mask - Google Patents
High contrast ratio membrane mask Download PDFInfo
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- US20010033634A1 US20010033634A1 US09/837,848 US83784801A US2001033634A1 US 20010033634 A1 US20010033634 A1 US 20010033634A1 US 83784801 A US83784801 A US 83784801A US 2001033634 A1 US2001033634 A1 US 2001033634A1
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- Prior art keywords
- membrane
- mask
- film
- membrane film
- mask body
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- 239000012528 membrane Substances 0.000 title claims abstract description 82
- 238000000034 method Methods 0.000 claims description 29
- 238000005530 etching Methods 0.000 claims description 17
- 238000000059 patterning Methods 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 12
- 229910001385 heavy metal Inorganic materials 0.000 claims description 11
- 230000000737 periodic effect Effects 0.000 claims description 3
- 229910003460 diamond Inorganic materials 0.000 claims description 2
- 239000010432 diamond Substances 0.000 claims description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 18
- 229910052710 silicon Inorganic materials 0.000 abstract description 18
- 239000010703 silicon Substances 0.000 abstract description 18
- 238000010894 electron beam technology Methods 0.000 abstract description 12
- 229910052721 tungsten Inorganic materials 0.000 description 22
- 239000010937 tungsten Substances 0.000 description 21
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 19
- 229910052581 Si3N4 Inorganic materials 0.000 description 16
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 16
- 230000008569 process Effects 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000000609 electron-beam lithography Methods 0.000 description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 4
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 4
- 238000001015 X-ray lithography Methods 0.000 description 3
- -1 chrome ions Chemical class 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 238000001039 wet etching Methods 0.000 description 3
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000001312 dry etching Methods 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000001020 plasma etching Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- 229910052582 BN Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000002513 implantation Methods 0.000 description 1
- 238000002164 ion-beam lithography Methods 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- 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
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/22—Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/04—Coating on selected surface areas, e.g. using masks
- C23C14/042—Coating on selected surface areas, e.g. using masks using masks
-
- 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
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/20—Masks or mask blanks for imaging by charged particle beam [CPB] radiation, e.g. by electron beam; Preparation thereof
-
- 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
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
- G03F1/34—Phase-edge PSM, e.g. chromeless PSM; Preparation thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
- H01L21/033—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers
- H01L21/0334—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane
- H01L21/0337—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
Definitions
- the present invention relates to a high contrast ratio membrane mask and, more particularly, to a membrane mask for use in an electron beam lithography or an X-ray lithography.
- the present invention also relates to a method for forming such a membrane mask.
- a membrane mask is used in an electron beam lithography and an X-ray lithography during a fabrication process for fabricating a semiconductor device.
- the membrane mask generally includes a mask body pattern used as a scattering film for scattering electron beams or an absorbing film for absorbing X-rays, a membrane film for supporting the mask body pattern, and a silicon substrate for supporting the membrane film.
- a conventional technique for forming a membrane mask will be described first with reference to FIGS. 1A to 1 C.
- a boron nitride film 42 having a thickness of 3 ⁇ m is deposited on a silicon wafer 41 by a CVD technique, followed by deposition of a tungsten film 43 thereon by using a high-frequency sputtering technique, as shown in FIG. 1A.
- the tungsten film 43 has a thickness around 1.5 ⁇ m and has a mixed-phase crystal structure including an a phase and a phase.
- a resist film 44 for an electron beam exposure is applied thereon by spin-coating, followed by exposure of an electron beam 45 to write a desired pattern on the resist film 44 .
- the resist film 44 is developed to form an electron beam mask having a desired pattern.
- the tungsten film 43 is subjected to a reactive ion etching (RIE) process using the resist film 44 as a mask to obtain a membrane mask having the desired pattern.
- RIE reactive ion etching
- the mixed-phase crystal structure of the tungsten film 43 including the ⁇ phase and the ⁇ phase affords a smaller internal stress of the tungsten film 43 .
- the smaller internal stress allows the membrane mask to have a lower distortion in the mask pattern if the membrane mask has a larger thickness for achieving a higher contrast ratio.
- the membrane mask have a higher patterning accuracy as well as a higher locational accuracy in view of the rapid development of the finer design rule in a semiconductor device.
- the tungsten film has a large internal stress due to the specific property of the tungsten film known in the heavy metals. The large internal stress causes a film distortion to thereby prevent the patterning accuracy and incurring peeling-off in the membrane mask.
- the patterning accuracy or prevention of the peeling-off may be achieved by a larger thickness of the tungsten film used as the electron beam scattering film or the X-ray absorbing film.
- the larger thickness of the mask body pattern increases the aspect ratio of the mask body pattern, which degrades the patterning accuracy of the mask body film.
- the aspect ratio is generally defined by a ratio of the film thickness to the width of the pattern on the mask film.
- the mixed-phase crystal structure of the tungsten film including the ⁇ phase and the ⁇ phase may reduce the film stress, whereby the thickness of the mask body may be reduced.
- the specified contrast ratio desired for the membrane mask prevents the reduction of the film thickness.
- the patterning accuracy of the mask body is not achieved in the conventional technique.
- the present invention provides a membrane mask including a wafer, a membrane film including a first material and supported by the wafer, and a mask body overlying the membrane film, the mask body having a mask pattern including an opening, the membrane film having a first area underlying the mask body other than the opening, the first area being formed by addition of atoms having an atomic number higher than an atomic number of the first material.
- the present invention also provides a method for forming a membrane mask including the steps of: forming a membrane film supported on a wafer; forming a resist mask on the membrane film; selectively implanting atoms into the membrane film by using the resist mask to form an implanted area, the atoms having an atomic number higher than an atomic number of a material included in the membrane film; forming a mask body film on the membrane film including the implanted area; and patterning the mask body film to have a pattern including an opening exposing the membrane film other than the implanted area.
- the implanted area including the atoms having a higher atomic number has a function of electron beam scattering or X-ray absorbing, thereby assisting the mask body.
- the implanted area thus improves the contrast ratio of the resultant pattern obtained by the mask body pattern without increasing the thickness of the mask body.
- FIGS. 1A to 1 D are sectional views of a conventional membrane mask, consecutively showing the fabrication steps therefor.
- FIG. 2 is a sectional view of a membrane mask according to an embodiment of the present invention.
- FIGS. 3A to 3 F are sectional views of the membrane mask of FIG. 2, consecutively showing the steps of a fabrication process therefor.
- FIGS. 4A to 4 F are sectional views of the membrane mask of FIG. 2, consecutively showing the steps of another fabrication process therefor.
- a membrane mask according to an embodiment of the present invention includes a silicon wafer 11 , a membrane film 12 formed thereon and implemented by a first material having a relatively low atomic number, and a mask body pattern 13 formed thereon and implemented by a second material having a relatively high atomic number.
- the membrane film 12 has an implanted area 14 at the bottom of the mask body pattern 13 except for the opening in the mask body pattern 13 .
- the implanted area 14 is formed by implanting or adding heavy atoms having an atomic number higher than the atomic number of the first material to the membrane film 12 .
- the heavy atoms in the implanted area 14 have a function of scattering electron beams or absorbing X-rays in association with the mask body pattern 13 .
- the area of the membrane film 12 other than the implanted area 14 has an inherent function for suitably passing therethrough electron beams or X-rays due to the absence of the heavy atoms therein.
- Examples of the first material in the membrane film 12 include silicon nitride (SiN), silicon carbide (SiC), boron nitride (BN), diamond (C) etc.
- the heavy atoms in the implanted area 14 of the membrane film 12 may be preferably selected from heavy metals, and more preferably selected from the heavy metals tabulated on he periodic table at the sixth period and the subsequent periods. Examples of the heavy metals include tungsten (W), tantalum (Ta), gold (Au), platinum (Pt), lead (Pb) etc.
- the implanted heavy atoms may include a plurality of heavy metals.
- the material for the mask body pattern 13 may be preferably selected from heavy metals or heavy alloys such as W, Ta, TaGe, TaReGe.
- the mask body pattern 13 may preferably include one or more of the heavy metals tabulated on the periodic table at the sixth period and the subsequent periods.
- FIGS. 3A to 3 F there is shown a fabrication process for fabricating a membrane mask according to an embodiment of the present invention.
- the membrane mask is used for an electron beam lithography, for example.
- a silicon nitride film (SiN) 22 is deposited on the top surface of a silicon wafer 21 having a diameter of 200 mm by using a LPCVD (low pressure chemical vapor deposition) technique to a thickness of 100 nm (nanometers). It is to be noted that the thickness of the silicon nitride film 22 is preferably 150 nm or less.
- the silicon nitride film 22 is spin-coated with resin to form a resin film thereon, followed by patterning thereof using an electron beam lithographic technique to form a resist pattern 23 , as shown in FIG. 3B.
- the resist pattern 23 has openings therein for implanted areas to be formed for scattering the electron beams.
- heavy metal ions such as tungsten or chrome ions are implanted into the silicon nitride film 22 by using a resist pattern 23 as a mask, thereby forming a heavy-metal-implanted area 24 .
- the resist pattern 23 is then removed, as shown in FIG. 3C.
- a tungsten film 25 is deposited on the silicon nitride film 22 including the heavy-metal-implanted area 24 by using a sputtering or LPCVD technique to a thickness of about 10 nm, as shown in FIG. 3D. It is to be noted that the thickness of the tungsten film 25 is preferably 20 nm or less.
- the tungsten film 25 is spin-coated with resist to form a resist film thereon, followed by an electron beam lithography thereof to form a resist pattern.
- the underlying tungsten film 25 is then selectively etched by using a dry-etching technique using the resist pattern, as shown in FIG. 3E.
- a mask pattern is formed on the bottom surface of the silicon wafer 21 , followed by anisotropic back etching of the silicon wafer 21 by a wet etching technique using potassium hydroxide (KOH) as an etchant and the silicon nitride film 22 as an etch stopper
- KOH potassium hydroxide
- the silicon nitride film 22 is formed as a membrane film having an implanted area 24 , as shown in FIG. 3F.
- the wet etching step may be replaced by a dry etching step.
- FIGS. 4A to 4 F there is shown another fabrication process for fabricating the membrane mask of FIG. 2 according to another embodiment.
- the membrane mask is used for an electron beam lithography, for example.
- a silicon nitride film 32 is deposited to a thickness of 130 nm by using a LPCVD technique on the top surface of a silicon wafer 32 having a diameter of 200 mm.
- a mask having a specified opening is then formed on the bottom surface of the silicon wafer 31 , followed by back etching of the silicon wafer 31 by a wet etching technique using KOH as an etchant, to thereby leave a film of the silicon wafer 31 having a thickness of 0.1 to 1 mm and underlying the silicon nitride film 32 , as shown in FIG. 4A.
- the silicon nitride film 32 is then spin-coated with resist to form a resist film thereon, followed by patterning thereof to form a resist pattern 33 , as shown in FIG. 4B.
- tungsten ions are selectively implanted into the silicon nitride film 32 by using the resist pattern 33 as a mask to form a heavy-metal-implanted area 34 .
- the resist pattern 33 is then removed, as shown in FIG. 4C.
- the order of the steps may be reversed so that the back etching step of the silicon wafer 31 is conducted after the implanting of the tungsten ions.
- tungsten is sputtered onto the silicon nitride film 32 including the heavy-metal-implanted area 34 , thereby forming a tungsten film 35 having a thickness of 15 nm, as shown in FIG. 4D.
- the tungsten film 35 is subjected to an electron beam lithographic patterning, whereby a portion of the tungsten film 35 is left on the heavy-metal-implanted area 34 , as shown in FIG. 4E.
- the remaining film 31 a of the silicon wafer 31 is removed by a back etching, whereby the silicon nitride film 32 is disposed as a membrane film, as shown in FIG. 4F.
- the final back etching step may be an isotropic etching step wherein an etching mask is not necessarily used.
- the silicon wafer may be subjected to a deformation due to a tensile stress applied from the membrane film after the back etching of the silicon wafer.
- the tensile stress of the membrane film is removed to some extent before the film for the mask body is formed. In this process, the distortion of the silicon wafer after the back etching of the silicon wafer can be alleviated, whereby the membrane mask has a lower deformation.
- the back etching of the silicon wafer may be conducted before the deposition of the mask body film, such as before or after the implantation of the heavy metal ions.
- the membrane mask of the present invention can be applied to an X-ray lithography and an ion beam lithography as well as an electron beam lithography.
Abstract
Description
- (a) Field of the Invention
- The present invention relates to a high contrast ratio membrane mask and, more particularly, to a membrane mask for use in an electron beam lithography or an X-ray lithography. The present invention also relates to a method for forming such a membrane mask.
- (b) Description of the Related Art
- A membrane mask is used in an electron beam lithography and an X-ray lithography during a fabrication process for fabricating a semiconductor device. The membrane mask generally includes a mask body pattern used as a scattering film for scattering electron beams or an absorbing film for absorbing X-rays, a membrane film for supporting the mask body pattern, and a silicon substrate for supporting the membrane film.
- A conventional technique for forming a membrane mask will be described first with reference to FIGS. 1A to1C. A
boron nitride film 42 having a thickness of 3 μm is deposited on asilicon wafer 41 by a CVD technique, followed by deposition of atungsten film 43 thereon by using a high-frequency sputtering technique, as shown in FIG. 1A. Thetungsten film 43 has a thickness around 1.5 μm and has a mixed-phase crystal structure including an a phase and a phase. - Subsequently, as shown in FIG. 1B, a
resist film 44 for an electron beam exposure is applied thereon by spin-coating, followed by exposure of anelectron beam 45 to write a desired pattern on theresist film 44. - Thereafter, as shown in FIG. 1C, the
resist film 44 is developed to form an electron beam mask having a desired pattern. Then, as shown in FIG. 1D, thetungsten film 43 is subjected to a reactive ion etching (RIE) process using theresist film 44 as a mask to obtain a membrane mask having the desired pattern. - In the conventional process as described above, it is known that the mixed-phase crystal structure of the
tungsten film 43 including the α phase and the β phase affords a smaller internal stress of thetungsten film 43. The smaller internal stress allows the membrane mask to have a lower distortion in the mask pattern if the membrane mask has a larger thickness for achieving a higher contrast ratio. - Recently, it is desired that the membrane mask have a higher patterning accuracy as well as a higher locational accuracy in view of the rapid development of the finer design rule in a semiconductor device. It is known that the tungsten film has a large internal stress due to the specific property of the tungsten film known in the heavy metals. The large internal stress causes a film distortion to thereby prevent the patterning accuracy and incurring peeling-off in the membrane mask. The patterning accuracy or prevention of the peeling-off may be achieved by a larger thickness of the tungsten film used as the electron beam scattering film or the X-ray absorbing film.
- The larger thickness of the mask body pattern, however, increases the aspect ratio of the mask body pattern, which degrades the patterning accuracy of the mask body film. The aspect ratio is generally defined by a ratio of the film thickness to the width of the pattern on the mask film.
- In the conventional technique shown in FIGS. 1A to1D, the mixed-phase crystal structure of the tungsten film including the α phase and the β phase may reduce the film stress, whereby the thickness of the mask body may be reduced. However, the specified contrast ratio desired for the membrane mask prevents the reduction of the film thickness. Thus, the patterning accuracy of the mask body is not achieved in the conventional technique.
- In view of the above, it is an object of the present invention to provide a membrane mask having a smaller thickness without degrading the contrast ratio and thus achieving a higher patterning accuracy.
- It is also an object of the present invention to provide a method for forming such a membrane mask.
- The present invention provides a membrane mask including a wafer, a membrane film including a first material and supported by the wafer, and a mask body overlying the membrane film, the mask body having a mask pattern including an opening, the membrane film having a first area underlying the mask body other than the opening, the first area being formed by addition of atoms having an atomic number higher than an atomic number of the first material.
- The present invention also provides a method for forming a membrane mask including the steps of: forming a membrane film supported on a wafer; forming a resist mask on the membrane film; selectively implanting atoms into the membrane film by using the resist mask to form an implanted area, the atoms having an atomic number higher than an atomic number of a material included in the membrane film; forming a mask body film on the membrane film including the implanted area; and patterning the mask body film to have a pattern including an opening exposing the membrane film other than the implanted area.
- In accordance with the membrane mask of the present invention and the membrane mask formed by the method of the present invention, the implanted area including the atoms having a higher atomic number has a function of electron beam scattering or X-ray absorbing, thereby assisting the mask body. The implanted area thus improves the contrast ratio of the resultant pattern obtained by the mask body pattern without increasing the thickness of the mask body.
- The above and other objects, features and advantages of the present invention will be more apparent from the following description, referring to the accompanying drawings.
- FIGS. 1A to1D are sectional views of a conventional membrane mask, consecutively showing the fabrication steps therefor.
- FIG. 2 is a sectional view of a membrane mask according to an embodiment of the present invention.
- FIGS. 3A to3F are sectional views of the membrane mask of FIG. 2, consecutively showing the steps of a fabrication process therefor.
- FIGS. 4A to4F are sectional views of the membrane mask of FIG. 2, consecutively showing the steps of another fabrication process therefor.
- Referring to FIG. 2, a membrane mask according to an embodiment of the present invention includes a
silicon wafer 11, amembrane film 12 formed thereon and implemented by a first material having a relatively low atomic number, and amask body pattern 13 formed thereon and implemented by a second material having a relatively high atomic number. - The
membrane film 12 has an implantedarea 14 at the bottom of themask body pattern 13 except for the opening in themask body pattern 13. The implantedarea 14 is formed by implanting or adding heavy atoms having an atomic number higher than the atomic number of the first material to themembrane film 12. The heavy atoms in the implantedarea 14 have a function of scattering electron beams or absorbing X-rays in association with themask body pattern 13. The area of themembrane film 12 other than the implantedarea 14 has an inherent function for suitably passing therethrough electron beams or X-rays due to the absence of the heavy atoms therein. - Examples of the first material in the
membrane film 12 include silicon nitride (SiN), silicon carbide (SiC), boron nitride (BN), diamond (C) etc. The heavy atoms in the implantedarea 14 of themembrane film 12 may be preferably selected from heavy metals, and more preferably selected from the heavy metals tabulated on he periodic table at the sixth period and the subsequent periods. Examples of the heavy metals include tungsten (W), tantalum (Ta), gold (Au), platinum (Pt), lead (Pb) etc. The implanted heavy atoms may include a plurality of heavy metals. - The material for the
mask body pattern 13 may be preferably selected from heavy metals or heavy alloys such as W, Ta, TaGe, TaReGe. Themask body pattern 13 may preferably include one or more of the heavy metals tabulated on the periodic table at the sixth period and the subsequent periods. - Referring to FIGS. 3A to3F, there is shown a fabrication process for fabricating a membrane mask according to an embodiment of the present invention. The membrane mask is used for an electron beam lithography, for example. In FIG. 3A, a silicon nitride film (SiN) 22 is deposited on the top surface of a
silicon wafer 21 having a diameter of 200 mm by using a LPCVD (low pressure chemical vapor deposition) technique to a thickness of 100 nm (nanometers). It is to be noted that the thickness of thesilicon nitride film 22 is preferably 150 nm or less. - Subsequently, the
silicon nitride film 22 is spin-coated with resin to form a resin film thereon, followed by patterning thereof using an electron beam lithographic technique to form a resist pattern 23, as shown in FIG. 3B. The resist pattern 23 has openings therein for implanted areas to be formed for scattering the electron beams. - Thereafter, heavy metal ions such as tungsten or chrome ions are implanted into the
silicon nitride film 22 by using a resist pattern 23 as a mask, thereby forming a heavy-metal-implantedarea 24. The resist pattern 23 is then removed, as shown in FIG. 3C. - A
tungsten film 25 is deposited on thesilicon nitride film 22 including the heavy-metal-implantedarea 24 by using a sputtering or LPCVD technique to a thickness of about 10 nm, as shown in FIG. 3D. It is to be noted that the thickness of thetungsten film 25 is preferably 20 nm or less. - Subsequently, the
tungsten film 25 is spin-coated with resist to form a resist film thereon, followed by an electron beam lithography thereof to form a resist pattern. Theunderlying tungsten film 25 is then selectively etched by using a dry-etching technique using the resist pattern, as shown in FIG. 3E. - Thereafter, a mask pattern is formed on the bottom surface of the
silicon wafer 21, followed by anisotropic back etching of thesilicon wafer 21 by a wet etching technique using potassium hydroxide (KOH) as an etchant and thesilicon nitride film 22 as an etch stopper Thus, thesilicon nitride film 22 is formed as a membrane film having an implantedarea 24, as shown in FIG. 3F. The wet etching step may be replaced by a dry etching step. - Referring to FIGS. 4A to4F, there is shown another fabrication process for fabricating the membrane mask of FIG. 2 according to another embodiment. The membrane mask is used for an electron beam lithography, for example. A
silicon nitride film 32 is deposited to a thickness of 130 nm by using a LPCVD technique on the top surface of asilicon wafer 32 having a diameter of 200 mm. A mask having a specified opening is then formed on the bottom surface of thesilicon wafer 31, followed by back etching of thesilicon wafer 31 by a wet etching technique using KOH as an etchant, to thereby leave a film of thesilicon wafer 31 having a thickness of 0.1 to 1 mm and underlying thesilicon nitride film 32, as shown in FIG. 4A. - The
silicon nitride film 32 is then spin-coated with resist to form a resist film thereon, followed by patterning thereof to form a resistpattern 33, as shown in FIG. 4B. Subsequently, tungsten ions are selectively implanted into thesilicon nitride film 32 by using the resistpattern 33 as a mask to form a heavy-metal-implantedarea 34. The resistpattern 33 is then removed, as shown in FIG. 4C. The order of the steps may be reversed so that the back etching step of thesilicon wafer 31 is conducted after the implanting of the tungsten ions. - Thereafter, tungsten is sputtered onto the
silicon nitride film 32 including the heavy-metal-implantedarea 34, thereby forming atungsten film 35 having a thickness of 15 nm, as shown in FIG. 4D. Thetungsten film 35 is subjected to an electron beam lithographic patterning, whereby a portion of thetungsten film 35 is left on the heavy-metal-implantedarea 34, as shown in FIG. 4E. - Subsequently, the remaining
film 31 a of thesilicon wafer 31 is removed by a back etching, whereby thesilicon nitride film 32 is disposed as a membrane film, as shown in FIG. 4F. The final back etching step may be an isotropic etching step wherein an etching mask is not necessarily used. - In the first fabrication process, there is a possibility that the silicon wafer may be subjected to a deformation due to a tensile stress applied from the membrane film after the back etching of the silicon wafer. On the other hand, in the second fabrication process, the tensile stress of the membrane film is removed to some extent before the film for the mask body is formed. In this process, the distortion of the silicon wafer after the back etching of the silicon wafer can be alleviated, whereby the membrane mask has a lower deformation.
- Since the above embodiments are described only for examples, the present invention is not limited to the above embodiments and various modifications or alterations can be easily made therefrom by those skilled in the art without departing from the scope of the present invention.
- For example, the back etching of the silicon wafer may be conducted before the deposition of the mask body film, such as before or after the implantation of the heavy metal ions. In addition, the membrane mask of the present invention can be applied to an X-ray lithography and an ion beam lithography as well as an electron beam lithography.
Claims (12)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP12-118908 | 2000-04-20 | ||
JP2000118908A JP2001307979A (en) | 2000-04-20 | 2000-04-20 | Membrane mask and its manufacturing method |
JP2000-118908 | 2000-04-20 |
Publications (2)
Publication Number | Publication Date |
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US20010033634A1 true US20010033634A1 (en) | 2001-10-25 |
US6351515B2 US6351515B2 (en) | 2002-02-26 |
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Application Number | Title | Priority Date | Filing Date |
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US09/837,848 Expired - Fee Related US6351515B2 (en) | 2000-04-20 | 2001-04-18 | High contrast ratio membrane mask |
Country Status (5)
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US (1) | US6351515B2 (en) |
JP (1) | JP2001307979A (en) |
KR (1) | KR20010098723A (en) |
CN (1) | CN1381871A (en) |
TW (1) | TW511145B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10561816B2 (en) * | 2006-09-21 | 2020-02-18 | Mercator Medsystems, Inc. | Dual modulus balloon for interventional procedures |
Families Citing this family (1)
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JP5233157B2 (en) * | 2007-04-24 | 2013-07-10 | パナソニック株式会社 | Piezoelectric device |
Family Cites Families (11)
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---|---|---|---|---|
DE3529966C1 (en) * | 1985-08-22 | 1987-01-15 | Kernforschungsz Karlsruhe | Process for the production of masks for X-ray depth lithography |
JPH02264420A (en) * | 1989-04-04 | 1990-10-29 | Fujitsu Ltd | X-ray exposing mask |
JPH05106046A (en) * | 1991-10-15 | 1993-04-27 | Fujitsu Ltd | Chemical vapor deposition apparatus and production of x-ray mask |
JPH0744148B2 (en) * | 1992-03-05 | 1995-05-15 | 株式会社ソルテック | Method for manufacturing double-sided absorber X-ray mask |
JPH0782989B2 (en) * | 1992-03-18 | 1995-09-06 | 株式会社ソルテック | Method for manufacturing double-sided absorber X-ray mask |
KR100209655B1 (en) * | 1996-11-30 | 1999-07-15 | 구자홍 | Method of manufacturing x-ray lithographic mask |
KR100218677B1 (en) * | 1996-12-26 | 1999-09-01 | 정선종 | X-ray mask and its manufacture |
US5942760A (en) * | 1997-11-03 | 1999-08-24 | Motorola Inc. | Method of forming a semiconductor device utilizing scalpel mask, and mask therefor |
JPH11162823A (en) * | 1997-12-01 | 1999-06-18 | Nikon Corp | Mask manufacturing member, mask and method for manufacturing same |
JPH11288863A (en) * | 1998-04-01 | 1999-10-19 | Mitsubishi Electric Corp | X-ray mask and manufacture thereof |
JPH11340127A (en) * | 1998-05-28 | 1999-12-10 | Nikon Corp | Etching method |
-
2000
- 2000-04-20 JP JP2000118908A patent/JP2001307979A/en active Pending
-
2001
- 2001-04-18 US US09/837,848 patent/US6351515B2/en not_active Expired - Fee Related
- 2001-04-19 KR KR1020010021001A patent/KR20010098723A/en not_active Application Discontinuation
- 2001-04-19 TW TW090109380A patent/TW511145B/en not_active IP Right Cessation
- 2001-04-20 CN CN01110777A patent/CN1381871A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10561816B2 (en) * | 2006-09-21 | 2020-02-18 | Mercator Medsystems, Inc. | Dual modulus balloon for interventional procedures |
Also Published As
Publication number | Publication date |
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KR20010098723A (en) | 2001-11-08 |
TW511145B (en) | 2002-11-21 |
CN1381871A (en) | 2002-11-27 |
US6351515B2 (en) | 2002-02-26 |
JP2001307979A (en) | 2001-11-02 |
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