Acrylate negative photoresist film for dry etching and preparation method thereof

Abstract

The present invention relates to the technical field of photoresists, and in particular to an acrylate negative photoresist film for dry etching and a preparation method thereof. The present invention provides an application of an organic metal compound containing unsaturated double bonds as a functional compound in improving the etching ratio of the acrylate negative photoresist film, wherein the unsaturated double bonds in the organic metal compound containing unsaturated double bonds can cross-link with an acrylate resin to generate a cross-linked product insoluble in alkali, and the metal element contained in the organic metal compound containing unsaturated double bonds can shield the plasma in the dry etching process after photolithography, thereby improving the etching ratio of the acrylate negative photoresist film.

Description

Technical Field

[0001] The invention relates to the technical field of photoresists, in particular to an acrylate negative photoresist film for dry etching and a preparation method thereof. Background Art

[0002] Photoresist is the most critical basic material for the development of microelectronics technology. It is also called photoresist. It is an etching-resistant thin film material whose solubility changes when exposed or irradiated by exposure sources such as ultraviolet light, electron beam, ion beam, excimer laser beam, and X-ray. After the photoresist film is exposed and developed to form a photolithography pattern, it will be dry or wet etched. The part of the substrate material not covered by the film is directly etched, while the substrate surface covered by the film is protected by the photoresist film and is not etched. Dry etching resistance is a very important evaluation index of photoresist. Excellent etching resistance can ensure that the photoresist can protect the substrate surface from damage during the etching process, and effectively simplify the etching process, greatly improving the yield of the etched product.

[0003] The existing photoresist used in dry etching process is usually a resin system such as phenolic, acrylate, poly (p-hydroxystyrene), etc. The theory is to improve the dry etching resistance by increasing the percentage of carbon atom content in the film, but the improvement effect is limited. The existing photoresist system has poor dry etching resistance and low etching ratio, which is only about 1:1 at most. In the deep etching demand, a thicker photoresist thickness is often required to achieve the target etching depth, resulting in low process efficiency and high production cost. In the deep etching process, the photoresist film thickness is usually increased and the photoresist hardening temperature before etching is increased in order to improve its etching resistance, but the effect is not ideal. There are also reports that a layer of inorganic or organic layer with high etching resistance is coated between the photoresist pattern and the etched substrate, that is, "resist lower layer" or "hard mask", to achieve the purpose of etching resistance, but the disadvantage of this solution is that the two-layer film or multi-layer film process operation is complicated, the efficiency is low, and the production cost is high. It is basically not used in conventional dry etching processes in China.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a new functional compound, so as to use it for preparing acrylate negative photoresist film, which can improve the etching ratio of acrylate negative photoresist film, thereby solving the technical problem of poor dry etching resistance of photoresist system in the prior art.

[0006] Another object of the present invention is to provide a composition containing the above-mentioned functional compound capable of improving the etching ratio, wherein the composition can be used to prepare an acrylate negative photoresist film, and the prepared acrylate negative photoresist film has a significantly improved etching ratio.

[0007] Another object of the present invention is to provide a method for preparing an acrylate negative photoresist film using the above-mentioned composition. By optimizing the preparation steps and parameters of the preparation method, the etching ratio of the obtained acrylate negative photoresist film can be significantly improved. At the same time, the preparation method can meet the requirements of being simple, easy to operate and suitable for promotion.

[0008] In order to solve the above technical problems and achieve the above objectives, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides the use of an organic metal compound containing an unsaturated double bond in improving the etching ratio of an acrylate negative photoresist film.

[0010] In an optional embodiment, the organometallic compound containing unsaturated double bonds has at least 1 double bond, preferably 1 to 4 double bonds.

[0011] In an optional embodiment, the metal element of the organic metal compound containing unsaturated double bonds is selected from at least one of magnesium, calcium, barium, titanium, zirconium, hafnium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, indium, tin or antimony.

[0012] In an optional embodiment, the organic metal compound containing an unsaturated double bond is zirconium acrylate.

[0013] In a second aspect, the present invention provides a composition for preparing an acrylate negative photoresist film, the composition comprising, by weight, 10 to 50 parts of an acrylate resin, 3 to 30 parts of an organic metal compound containing an unsaturated double bond, 0.5 to 10 parts of a photoinitiator and 10 to 80 parts of an organic solvent.

[0014] In an optional embodiment, the organometallic compound containing unsaturated double bonds has at least 1 double bond, preferably 1 to 4 double bonds.

[0015] In an optional embodiment, the metal element of the organic metal compound containing unsaturated double bonds is selected from at least one of magnesium, calcium, barium, titanium, zirconium, hafnium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, indium, tin or antimony.

[0016] In an optional embodiment, the photoinitiator is selected from 907, 184 or TPO.

[0017] In an optional embodiment, the organic solvent is selected from at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl acetate or ethyl lactate.

[0018] In a third aspect, the present invention provides a method for preparing an acrylate negative photoresist film, the preparation method comprising weighing an acrylate resin, an organic metal compound containing an unsaturated double bond, a photoinitiator and an organic solvent according to the formula amount described in any one of the aforementioned embodiments, mixing them evenly, and then filtering through a filter membrane, spin coating, mask exposure, immersion development, cleaning and drying in sequence to obtain an acrylate negative photoresist film for dry etching.

[0019] Preferably, the pore size of the filter membrane used in the membrane filtration is 0.01-2 μm, preferably 0.2 μm.

[0020] Preferably, the film thickness of the spin coating is 1-10 μm, preferably 3 μm.

[0021] Preferably, the reported dose of the mask exposure is 10-200 mJ / cm 2 , preferably 100 mJ / cm 2 .

[0022] Preferably, the immersion liquid used in the immersion development is a tetramethylammonium hydroxide aqueous solution.

[0023] Preferably, a hot plate is used for pre-baking during the spin coating process, a hot plate is used for intermediate baking after mask exposure and before immersion development, and a hot plate is used for film hardening after cleaning and drying; the pre-baking temperature is 90~120℃, and the pre-baking time is 30~90s; the intermediate baking temperature is 90~120℃, and the intermediate baking time is 30~90s; the film hardening temperature is 90~120℃, and the film hardening time is 30~90s.

[0024] Preferably, the pre-baking temperature is 110° C., and the pre-baking time is 60 seconds; the intermediate baking temperature is 120° C., and the intermediate baking time is 60 seconds; the film hardening temperature is 110° C., and the film hardening time is 60 seconds.

[0025] The present invention provides an application of an organic metal compound containing unsaturated double bonds as a functional compound in improving the etching ratio of an acrylate negative photoresist film. The unsaturated double bonds in the organic metal compound containing unsaturated double bonds can be cross-linked with an acrylate resin to generate a cross-linked product insoluble in alkali, and the metal element contained in the organic metal compound containing unsaturated double bonds can chemically react with plasma in a dry etching process to generate a metal compound that is difficult to gasify. The compound is gradually deposited on the surface of the photoresist, making it increasingly difficult to etch, thereby improving the etching ratio of the acrylate negative photoresist film.

[0026] The invention provides a composition for preparing an acrylate negative photoresist film, wherein an organic metal compound containing an unsaturated double bond is added to the composition, and after a suitable ratio is adjusted, the added organic metal compound containing an unsaturated double bond can achieve an excellent cross-linking effect with an acrylate resin during the process of preparing the acrylate negative photoresist film, and the metal element contained in the composition can also play a role in shielding plasma etching, thereby improving the etching ratio.

[0027] The present invention also provides a method for preparing an acrylate negative photoresist film using the above composition. The acrylate negative photoresist film for dry etching prepared by the method has a thickness of 1 to 10 μm. It has been verified that the etching ratio for the gallium nitride substrate can reach 0.5 to 0.7:1, which significantly improves the etching ratio compared with the prior art. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0029] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In a specific embodiment, in a first aspect, the present invention provides the use of an organic metal compound containing an unsaturated double bond in improving the etching ratio of an acrylate negative photoresist film.

[0031] In an optional embodiment, the organometallic compound containing unsaturated double bonds has at least 1 double bond, preferably 1 to 4 double bonds.

[0032] In an optional embodiment, the metal element of the organic metal compound containing unsaturated double bonds is selected from at least one of magnesium, calcium, barium, titanium, zirconium, hafnium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, indium, tin or antimony.

[0033] In an optional embodiment, the organic metal compound containing unsaturated double bonds is zirconium acrylate. The metal element in the organic metal compound exhibits a significant shielding plasma etching effect after being used to prepare an acrylic ester negative photoresist film.

[0034] In combination with the first aspect, the second aspect of the present invention provides a composition for preparing an acrylate negative photoresist film, wherein the composition comprises, by weight, 10 to 50 parts of an acrylate resin, 3 to 30 parts of an organic metal compound containing an unsaturated double bond, 0.5 to 10 parts of a photoinitiator and 10 to 80 parts of an organic solvent.

[0035] The main resin is an acrylic resin containing unsaturated double bonds, including one or more of aliphatic acrylates, polyurethane acrylates, epoxy acrylates, etc., such as the Trust series resins of U-SUNNY and the ACA series resins of DAICEL-ALLNEX. The molecular weight of the resin is 1000-30000.

[0036] In an optional embodiment, the organometallic compound containing unsaturated double bonds has at least 1 double bond, preferably 1 to 4 double bonds.

[0037] In an optional embodiment, the metal element of the organic metal compound containing unsaturated double bonds is selected from at least one of magnesium, calcium, barium, titanium, zirconium, hafnium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, cadmium, indium, tin or antimony.

[0038] In an optional embodiment, the photoinitiator is selected from 907, 184 or TPO.

[0039] In an optional embodiment, the organic solvent is selected from at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, ethyl acetate or ethyl lactate.

[0040] In combination with the second aspect, the third aspect of the present invention provides a method for preparing an acrylate negative photoresist film, the preparation method comprising weighing an acrylate resin, an organic metal compound containing an unsaturated double bond, a photoinitiator and an organic solvent according to the formula amount described in any one of the aforementioned embodiments, mixing them evenly, and then filtering through a filter membrane, spin coating, mask exposure, immersion development, cleaning and drying in sequence to obtain an acrylate negative photoresist film for dry etching.

[0041] Preferably, the pore size of the filter membrane used in the membrane filtration is 0.01-2 μm, preferably 0.2 μm.

[0042] Preferably, the film thickness of the spin coating is 1-10 μm, preferably 3 μm.

[0043] Preferably, the reported dose of the mask exposure is 10-200 mJ / cm 2 , preferably 100 mJ / cm 2 .

[0044] Preferably, the immersion liquid used in the immersion development is a tetramethylammonium hydroxide aqueous solution.

[0045] Preferably, a hot plate is used for pre-baking during the spin coating process, a hot plate is used for intermediate baking after mask exposure and before immersion development, and a hot plate is used for film hardening after cleaning and drying; the pre-baking temperature is 90~120℃, and the pre-baking time is 30~90s; the intermediate baking temperature is 90~120℃, and the intermediate baking time is 30~90s; the film hardening temperature is 90~120℃, and the film hardening time is 30~90s.

[0046] Preferably, the pre-baking temperature is 110° C., and the pre-baking time is 60 seconds; the intermediate baking temperature is 120° C., and the intermediate baking time is 60 seconds; the film hardening temperature is 110° C., and the film hardening time is 60 seconds.

[0047] Some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0048] Example 1

[0049] This embodiment provides a composition for preparing an acrylate negative photoresist film, the composition comprising 50 g of DAICEL-ALLNEX acrylic resin ACA Z250, 5 g of zirconium acrylate, 0.5 g of photoinitiator 907 and 100 g of propylene glycol methyl ether acetate.

[0050] The solvent in this embodiment can be conventionally replaced with propylene glycol methyl ether, ethyl acetate or ethyl lactate.

[0051] Example 2

[0052] This embodiment provides a composition for preparing an acrylate negative photoresist film, the composition comprising 50 g of DAICEL-ALLNEX acrylic resin ACA Z250, 10 g of zirconium acrylate, 0.5 g of photoinitiator 907 and 100 g of propylene glycol methyl ether acetate.

[0053] Example 3

[0054] This embodiment provides a composition for preparing an acrylate negative photoresist film, the composition comprising 50 g of DAICEL-ALLNEX acrylic resin ACA Z250, 10 g of zirconium acrylate, 0.5 g of photoinitiator 184 and 100 g of propylene glycol methyl ether acetate.

[0055] Example 4

[0056] This embodiment provides a composition for preparing an acrylate negative photoresist film, the composition comprising 50 g of DAICEL-ALLNEX acrylic resin ACA Z250, 10 g of copper acetylacetonate, 0.5 g of photoinitiator 907 and 100 g of propylene glycol methyl ether acetate.

[0057] Example 5

[0058] This embodiment provides a composition for preparing an acrylate negative photoresist film, the composition comprising 50 g of DAICEL-ALLNEX acrylic resin ACA Z250, 10 g of nickel acetylacetonate, 0.5 g of photoinitiator 907 and 100 g of propylene glycol methyl ether acetate.

[0059] Examples 6 and 7

[0060] Example 6 and Example 7 respectively provide a composition for preparing an acrylate negative photoresist film, and the composition composition is shown in the following table:

[0061] Table 1 Examples 6 and 7 provide the composition of the composition

[0062]

[0063] Embodiments 8 to 14

[0064] In Examples 8 to 14, the compositions provided in Examples 1 to 7 were used as raw materials, respectively. The raw materials were weighed and mixed, and after being fully dissolved, they were filtered through a filter membrane with a pore size of 0.2 μm to obtain photoresists 1 to 7.

[0065] Embodiments 15 to 21

[0066] This group of embodiments respectively provide methods for preparing acrylate negative photoresist films by spin coating using photoresists 1 to 7, and the specific steps are as follows:

[0067] Use photoresists 1 to 7 respectively, adopt spin coating method, use hot plate pre-bake (PAB) 110℃ / 60s, adjust the speed so that the film thickness after drying is 3μm, through the mask, through the exposure machine (contact or projection) after i-line exposure, the exposure metering is 100mJ / cm 2 , use hot plate baking (PEB) at 120℃ / 60s, soak and develop with 2.38wt% TMAH for 60s, wash with deionized water and harden with hot plate at 110℃ / 60s to make adhesive films 1~7 for dry etching.

[0068] Comparative Example 1

[0069] This comparative example provides a composition for preparing an acrylate negative photoresist film, the composition comprising 50 g of DAICEL-ALLNEX acrylic resin ACA Z250, 10 g of dipentaerythritol hexaacrylate, 0.5 g of photoinitiator 907 and 100 g of propylene glycol methyl ether acetate.

[0070] After the above composition is fully dissolved, it is filtered with a filter membrane with a pore size of 0.2μm to obtain a comparative photoresist 1, and then the spin coating method is used, and the hot plate pre-bake (PAB) is used for 110℃ / 60s. The rotation speed is adjusted so that the film thickness after drying is 3μm. After passing through the mask, the exposure machine (contact or projection) is exposed to i-line, and the exposure metering is 100mJ / cm 2 , hot plate baking (PEB) 120℃ / 60s, immersion development with 2.38wt% TMAH for 60s, deionized water washing and hot plate hardening at 110℃ / 60s, thus making comparative film 1.

[0071] Experimental Example 1

[0072] The etching ratios of the films 1 to 7 obtained in the above examples 15 to 21 and the comparative film 1 were tested using the following testing method:

[0073] Inductively coupled plasma was used to etch the gallium nitride substrate. The etching gases were chlorine and boron trichloride with flow rates of 30 ml / min and 10 ml / min respectively. The ICP power was 280 W, the RF power was 50 W, the etching pressure was 0.4 Pa, and the etching time was 400 s. A step profiler was used to measure the film thickness loss of the photoresist and the etching depth of the substrate. The etching ratio was calculated by the photoresist thickness loss / substrate etching depth. The results are shown in the following table.

[0074] Table 2 Etching ratio results of six films in Experimental Example 1

[0075] Photoresist film thickness loss nm Substrate etching depth nm Etching ratio Film 1 1580 2320 0.681:1 Film 2 1223 2289 0.534:1 Film 3 1251 2334 0.536:1 Film 4 1240 2296 0.540:1 Film 5 1253 2301 0.545:1 Comparison film 1 2874 2312 1.243:1

[0076] It can be seen from the above test results that the negative photoresist of the present invention can significantly improve the dry etching resistance of the photoresist.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composition for preparing an acrylate negative photoresist film, characterized in that: The composition comprises: Acrylate resin 50g, zirconium acrylate 5g, photoinitiator 907 0.5g and propylene glycol methyl ether acetate 100g.

2. An acrylic ester negative photoresist film, characterized in that: The acrylate negative photoresist film is prepared from the composition for preparing acrylate negative photoresist film according to claim 1.

3. A method for preparing an acrylic ester negative photoresist film according to claim 2, characterized in that: The preparation method comprises: Acrylate resin, zirconium acrylate, photoinitiator and propylene glycol methyl ether acetate are weighed, mixed, filtered through a filter membrane, spin-coated, exposed through a mask, developed through immersion, cleaned and dried to obtain an acrylate negative photoresist film for dry etching.

4. The method for preparing an acrylic ester negative photoresist film according to claim 3, characterized in that: The pore size of the filter membrane used in the membrane filtration is 0.01-2 μm.

5. The method for preparing an acrylic acid ester negative photoresist film according to claim 3, characterized in that: The film thickness of the spin coating is 1-10 μm.

6. The method for preparing an acrylate negative photoresist film according to claim 3, characterized in that: The reported dose for the mask exposure is 10-200 mJ / cm 2 .

7. The method for preparing an acrylic acid ester negative photoresist film according to claim 3, characterized in that: The immersion solution used in the immersion development includes one or more of a tetramethylammonium hydroxide aqueous solution, a sodium hydroxide solution or a potassium hydroxide solution.

8. The method for preparing an acrylic ester negative photoresist film according to claim 3, characterized in that: In the process of spin coating, a hot plate is used for pre-baking. After the mask is exposed and before immersion development, a hot plate is used for intermediate baking. After cleaning and drying, a hot plate is used for hardening the film. The pre-baking temperature is 90-120°C, and the pre-baking time is 30-90s; The intermediate baking temperature is 90-120°C and the intermediate baking time is 30-90s; The film hardening temperature is 90-120° C., and the film hardening time is 30-90 seconds.

9. The method for preparing an acrylic ester negative photoresist film according to claim 8, characterized in that: The pre-baking temperature is 110°C and the pre-baking time is 60s; The intermediate baking temperature is 120°C and the intermediate baking time is 60s; The film hardening temperature is 110° C. and the film hardening time is 60 seconds.

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