CN111522208A - Method for stripping metal film by using positive photoresist as mask - Google Patents
Method for stripping metal film by using positive photoresist as mask Download PDFInfo
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- CN111522208A CN111522208A CN202010372353.XA CN202010372353A CN111522208A CN 111522208 A CN111522208 A CN 111522208A CN 202010372353 A CN202010372353 A CN 202010372353A CN 111522208 A CN111522208 A CN 111522208A
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- photoresist
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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
- G03F7/42—Stripping or agents therefor
- G03F7/422—Stripping or agents therefor using liquids only
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- 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
- H01L21/02104—Forming layers
- H01L21/02697—Forming conducting materials on a substrate
Abstract
The invention discloses a method for stripping a metal film by using positive photoresist as a mask. Coating glue on a substrate, prebaking, exposing, developing, cleaning, flood exposing, plating metal and stripping, wherein the stripping comprises the following steps: and pasting a blue film on the surface of the substrate, tearing off the blue film, and removing the metal with glue at the bottom by using the viscosity of the blue film. And finally, placing the substrate in an organic solvent, and removing the residual photoresist on the surface of the substrate and the residual metal on the photoresist. The invention adopts the traditional positive photoresist, uses the normal exposure energy and the exposure time of the positive photoresist in a photoetching machine to carry out flood exposure on the whole surface, and then carries out film coating. After the positive photoresist is subjected to flood exposure, the cross-linking of the photoresist is changed, the adhesion is reduced, and intermolecular chain scission reaction occurs, so that pinholes appear on the surface of the photoresist, the surface adhesion of the metal film and the positive photoresist is poor, the metal layer with the photoresist at the bottom can be directly torn off by using a blue film, and the defect that the metal with the right angle or the metal close to the right angle is not easy to lift off after the positive photoresist is developed is overcome.
Description
Technical Field
The invention relates to a method for stripping a metal film by using positive photoresist as a mask, belonging to the field of semiconductor chip processing.
Background
The use of lift-off technology to produce fine metal patterns is a very valuable technology in the micron and submicron range. The basic sequence of the stripping technology is that firstly, one or more layers of negative photoresist are coated on the clean surface of a substrate, after different processes such as pre-baking, exposure, post-baking, development and the like are carried out, an inverted trapezoidal photoresist side section geometric figure is obtained on the surface of the substrate, then a metal layer is deposited on the surface of the substrate by an evaporation or sputtering method, finally, the photoresist and metal on the photoresist are stripped off, and the metal layer which is in close contact with the substrate is remained.
The peeling technique is generally classified into negative photoresist peeling and pattern reversal peeling. The thickness of the metal pattern lines is limited by the lithographic resolution, and the size of the mask pattern must be precisely controlled in order to fully exploit the capability of the lift-off process. The positive photoresist has the advantages of high sensitivity, small expansion deformation and good stability of formed patterns. But the positive photoresist is not easy to lift off because the positive photoresist forms a shape similar to a right angle after exposure and development.
Negative photoresist stripping is easier to realize because the realized pattern is generally in an inverted trapezoid shape, and the metal film and the photoresist easily form a cross section required for stripping. However, the negative photoresist itself has significant disadvantages, i.e., high expansion rate, poor stability, low resolution, and very high cost, and further has one more post-exposure baking step before development.
CN 108398860A-a stripping method of semiconductor laser chip metal discloses a stripping method, namely a pattern reversal stripping method, which adopts reversal glue and carries out two times of exposure, wherein the second time of exposure is flood exposure, the photoresist is changed from positive glue to negative glue, the formed pattern is in a reversed trapezoid shape, and a metal film and the photoresist form a section, thereby achieving the purpose of easy stripping. Such pattern reversal glue is more expensive and the process increases. And is not suitable for mass production of chips.
Disclosure of Invention
The invention aims to provide a method for stripping a metal film by using a positive photoresist as a mask layer.
The technical scheme adopted by the invention is as follows:
a method for stripping a metal film by using positive photoresist as a mask is characterized in that: coating a layer of positive glue on a substrate, carrying out pre-baking, exposure, development, cleaning and flood exposure treatment, plating metal on the surface of the positive glue, then stripping, adhering a blue film on the whole surface of the substrate plated with the metal during stripping, tearing off the blue film, removing the metal with glue at the bottom by using the viscosity of the blue film, finally soaking the substrate in an organic solution, and removing the residual photoresist on the surface of the substrate and the residual metal on the photoresist.
Preferably, the organic solvent is normal temperature acetone solution or N-methyl pyrrolidone at 90 ℃, and the soaking time is 15 min.
Preferably, the exposure and flood exposure are performed at 20 milliwatts per centimeter squared and 3.5 seconds each.
The invention realizes the transfer of the pattern by adopting the traditional positive glue and single-layer glue processes and mainly increases the flood exposure process. And then the metal film is deposited by evaporation or sputtering, the metal film with positive photoresist at the bottom can be directly removed by using a blue film, and the residual photoresist is removed by using acetone or N-methylpyrrolidone, so that the stripping efficiency is effectively improved. The invention has the beneficial effects that:
1) the invention adopts the traditional positive photoresist, and the negative photoresist operation is adopted in the common stripping process, because the shape of the positive photoresist after exposure and development is similar to a right angle, the positive photoresist is not easy to lift off after being covered by metal, and the negative photoresist after exposure and development is inverted trapezoid, and the positive photoresist is easy to lift off after being covered by metal. However, the price of the negative glue is 4-5 times that of the positive glue, and the negative glue is subjected to one-step exposure and baking in the operation process compared with the positive glue, so that the cost is saved by about 60% by using the positive glue, and the process time is shortened by about 30 minutes.
2) The glue thickness can be less than 2 microns by adopting a single-layer glue process.
3) After the positive photoresist is exposed and developed, metal is not directly plated, but the substrate is not used for a photoetching plate, the whole surface is subjected to flood exposure by using the energy and the exposure time of the normal exposure of the positive photoresist in a photoetching machine, and then the film is plated. After the positive photoresist is subjected to flood exposure, the cross-linking of the photoresist is changed, the adhesion is reduced, and the intermolecular chain scission reaction occurs, so that pinholes appear on the surface of the photoresist, the surface adhesion of the metal film and the positive photoresist is poor, the metal layer with the photoresist at the bottom can be directly torn off by using the blue film, the defect that the metal with the photoresist at the right angle or close to the right angle is not easy to lift off after the positive photoresist is developed is overcome, the stripping efficiency is improved, and the stripping effect is optimized.
4) After stripping, residual glue and a very small amount of metal films at the edge of the substrate can be removed by using acetone or N-methylpyrrolidone, a special solvent is not needed, and the cost is saved.
5) The verticality of the side wall of the formed metal pattern is high, and the resolution of the pattern is guaranteed.
6) The stripped metal pattern has no residual gold and no residual glue.
Drawings
FIG. 1 is a flow chart of a negative photoresist mask stripping process.
FIG. 2 is a flow chart of a single-layer positive photoresist stripping process of the present invention.
FIG. 3 is a schematic diagram of a negative photoresist mask stripping process.
FIG. 4 is a schematic diagram of a single-layer positive photoresist stripping process according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
The method for stripping the metal film by positive photoresist comprises the following steps:
(1) uniformly coating the positive glue 2 on the surface of the substrate 1 by using a glue coater, pre-drying, and uniformly coating at a glue-homogenizing rotation speed: 5500 revolutions per minute, gum thickness: 1.8 micron, prebaking: 110 ℃ for 180 seconds;
(2) placing a photoetching plate 3 on the positive photoresist 2, and carrying out exposure by using a photoetching machine, wherein the exposure energy is as follows: 20 milliwatts per square centimeter for 3.5 seconds;
(3) developing with a developing solution, wherein the developing time is as follows: 35 seconds;
(4) performing flood exposure by using a photoetching machine, wherein the flood exposure energy is as follows: 20 milliwatts per square centimeter for 3.5 seconds;
(5) carrying out metal coating by using an evaporation table or a sputtering table; three layers of metal of titanium, platinum and gold are evaporated, and the thickness is as follows: 10nm, 50nm and 100 nm.
(6) Tearing off the metal film with glue at the bottom by using a blue film;
(7) and soaking the substrate in normal-temperature acetone or 90 ℃ N-methyl pyrrolidone for 15min to remove the photoresist on the substrate and a very small amount of metal film remained at the edge of the substrate, thereby completing the stripping of the metal film. No residual metal remained after stripping with the blue film.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (3)
1. A method for stripping a metal film by using positive photoresist as a mask is characterized in that: coating a layer of positive glue on a substrate, carrying out pre-baking, exposure, development, cleaning and flood exposure treatment, plating metal on the surface of the positive glue, then stripping, adhering a blue film on the whole surface of the substrate plated with the metal during stripping, tearing off the blue film, removing the metal with glue at the bottom by using the viscosity of the blue film, finally soaking the substrate in an organic solution, and removing the residual photoresist on the surface of the substrate and the residual metal on the photoresist.
2. The method of claim 1, wherein the metal film is stripped by using a positive photoresist as a mask, the method comprising: the organic solvent is normal temperature acetone solution or N-methyl pyrrolidone at 90 deg.C, and soaking time is 15 min.
3. The method for stripping a metal film by using a positive photoresist as a mask according to claim 1 or 2, characterized in that: both the exposure and flood exposure were performed at 20 mw/cm for 3.5 seconds.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010372353.XA CN111522208A (en) | 2020-05-06 | 2020-05-06 | Method for stripping metal film by using positive photoresist as mask |
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| CN202010372353.XA CN111522208A (en) | 2020-05-06 | 2020-05-06 | Method for stripping metal film by using positive photoresist as mask |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112563129A (en) * | 2020-12-11 | 2021-03-26 | 苏州工业园区纳米产业技术研究院有限公司 | Metal stripping process for silicon wafer with high-step structure |
| CN113867104A (en) * | 2021-09-01 | 2021-12-31 | 安徽光智科技有限公司 | Preparation method of photoresist structure for Lift-off |
| CN114815003A (en) * | 2022-03-17 | 2022-07-29 | 成都国泰真空设备有限公司 | Optical film edge metallization treatment process |
| CN117031889A (en) * | 2023-08-29 | 2023-11-10 | 无锡市华辰芯光半导体科技有限公司 | Single-layer positive photoresist photoetching method |
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|---|---|---|---|---|
| US6372414B1 (en) * | 1999-03-12 | 2002-04-16 | Clariant Finance (Bvi) Limited | Lift-off process for patterning fine metal lines |
| CN103293850A (en) * | 2013-05-08 | 2013-09-11 | 中国电子科技集团公司第五十五研究所 | Single-layered positive photoresist photoetching method applied to metal stripping |
| CN108037637A (en) * | 2017-11-30 | 2018-05-15 | 深圳华远微电科技有限公司 | A kind of double-deck glue stripping technology of SAW filter application pan-exposure |
| CN108398860A (en) * | 2018-03-21 | 2018-08-14 | 福建中科光芯光电科技有限公司 | A kind of stripping means of semiconductor laser chip metal |
| CN108803261A (en) * | 2018-06-08 | 2018-11-13 | 大连芯冠科技有限公司 | The metallic pattern processing method for facilitating single layer positive photoresist to remove |
| CN109461652A (en) * | 2018-10-31 | 2019-03-12 | 无锡中微晶园电子有限公司 | A method of it is abnormal to improve thick metal layers LIFT OFF technique figure |
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2020
- 2020-05-06 CN CN202010372353.XA patent/CN111522208A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6372414B1 (en) * | 1999-03-12 | 2002-04-16 | Clariant Finance (Bvi) Limited | Lift-off process for patterning fine metal lines |
| CN103293850A (en) * | 2013-05-08 | 2013-09-11 | 中国电子科技集团公司第五十五研究所 | Single-layered positive photoresist photoetching method applied to metal stripping |
| CN108037637A (en) * | 2017-11-30 | 2018-05-15 | 深圳华远微电科技有限公司 | A kind of double-deck glue stripping technology of SAW filter application pan-exposure |
| CN108398860A (en) * | 2018-03-21 | 2018-08-14 | 福建中科光芯光电科技有限公司 | A kind of stripping means of semiconductor laser chip metal |
| CN108803261A (en) * | 2018-06-08 | 2018-11-13 | 大连芯冠科技有限公司 | The metallic pattern processing method for facilitating single layer positive photoresist to remove |
| CN109461652A (en) * | 2018-10-31 | 2019-03-12 | 无锡中微晶园电子有限公司 | A method of it is abnormal to improve thick metal layers LIFT OFF technique figure |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112563129A (en) * | 2020-12-11 | 2021-03-26 | 苏州工业园区纳米产业技术研究院有限公司 | Metal stripping process for silicon wafer with high-step structure |
| CN113867104A (en) * | 2021-09-01 | 2021-12-31 | 安徽光智科技有限公司 | Preparation method of photoresist structure for Lift-off |
| CN114815003A (en) * | 2022-03-17 | 2022-07-29 | 成都国泰真空设备有限公司 | Optical film edge metallization treatment process |
| CN117031889A (en) * | 2023-08-29 | 2023-11-10 | 无锡市华辰芯光半导体科技有限公司 | Single-layer positive photoresist photoetching method |
| CN117031889B (en) * | 2023-08-29 | 2024-04-02 | 无锡市华辰芯光半导体科技有限公司 | Single-layer positive photoresist photoetching method |
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