Resin for immersed photoresist, preparation method and immersed photoresist

Abstract

The invention is suitable for the technical field of semiconductors, and provides a resin for an immersed photoresist, a preparation method and the immersed photoresist. The preparation method comprises the following steps: adding an initiator, ethylcyclopentanol methacrylate, hydroxyadamantyl methacrylate, butyrolactone methacrylate and a reaction solvent into a reaction container, heating to carry out polymerization reaction, adding a fluorine-containing monomer into the reaction container at the later stage of the reaction, and continuously heating to carry out reaction, so as to obtain the fluorine-containing polymer. According to the present invention, the fluorine-containing resin and the matrix resin are combined so as to generate the immersed photoresist resin with the part of the fluorine-containing resin and the matrix resin, the immersed photoresist resin can be directly used as the resin component in the photoresist without adding other resins, and the fluorine-containing resin can be gathered on the surface of the photoresist so as to provide the topcoat layer effect, such that the photocuring effect can be easily achieved, and the photocuring effect can be easily achieved; and meanwhile, the problem that the hydrophobic high-molecular compound is not matched with the photoresist matrix resin does not exist.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a resin for immersion photoresist, a preparation method and the immersion photoresist. Background Art

[0002] Photoresist (also known as resist composition) is an indispensable raw material for manufacturing semiconductor chips. When preparing chips, photoresist can transfer the fine pattern on the mask to the substrate through processes such as coating, baking, exposure, development, and etching. The shorter the exposure wavelength, the higher the resolution of the photoresist. The exposure wavelength has gone through the development process of G line (436nm), I line (365nm), KrF (248nm), ArF&ArFi (193nm&134nm), and EUV (13.5nm), and the photolithography process has continued to improve. At present, ArF immersion lithography is widely used in the preparation of mid-to-high-end chips.

[0003] The existing formula of ArF immersion photoresist consists of resin, photoacid generator, quencher, etc. The most common photoacid generators are ionic sulfonium salts and iodonium salts. Such photoacid generators have a certain solubility in deionized water. When applied to immersion lithography process technology, the photoacid generator can precipitate from the photoresist and dissolve into the filling medium deionized water, which will contaminate the lens of the lithography machine on the one hand, and affect the formula ratio of the photoresist on the other hand, thereby affecting the exposure reaction and lithography pattern.

[0004] In order to prevent the effective components of the photoresist from dissolving out, the prior art applies a top coating layer (topcoat layer) on the photoresist to prevent the photoacid generator and other water-soluble components from entering the deionized water; or, a hydrophobic polymer compound with alkali solubility is added to the photoresist, and the hydrophobic polymer compound can automatically generate a protective layer on the surface of the photoresist during the photoresist coating process, playing the role of the topcoat layer. However, these two methods have the problems of complex process, high process difficulty, or the hydrophobic polymer compound does not match the main resin of the photoresist, which affects the quality of photolithography exposure. Summary of the invention

[0005] In view of the above problems, the present invention provides an immersion photoresist resin, a preparation method and an immersion photoresist. The preparation method of the immersion photoresist resin can be used to obtain an immersion photoresist resin containing a certain proportion of fluorine-containing resin. When the immersion photoresist resin is used to prepare the photoresist, no other resins need to be added. The fluorine-containing resin can be gathered on the surface of the photoresist to play the role of a topcoat layer. At the same time, there is no problem of mismatch between the hydrophobic polymer compound and the main resin of the photoresist.

[0006] One aspect of the present invention provides a method for preparing a resin for immersion photoresist, the method comprising:

[0007] Add an initiator, ethyl cyclopentanol methacrylate, hydroxyadamantyl methacrylate, butyrolactone methacrylate and a reaction solvent into a reaction container, heat to 60°C to 80°C for reaction, and after reacting for 6h to 8h, add a fluorine-containing monomer into the reaction container, and continue heating to react for 30min to 60min;

[0008] After the reaction is completed, a precipitation treatment is performed using an organic solvent to obtain a resin for immersion photoresist.

[0009] Another aspect of the present invention provides an immersion photoresist resin obtained according to the above-mentioned preparation method, wherein the proportion of fluorine-containing monomers in the immersion photoresist resin is 2% to 8%.

[0010] Another aspect of the present invention provides an immersion photoresist, which includes: the aforementioned immersion photoresist resin, a photoacid generator, a quencher, and an organic solvent.

[0011] Compared with the prior art, the present application provides a resin for immersion photoresist, a preparation method and an immersion photoresist in various aspects, and these aspects can achieve at least one of the following beneficial effects: the preparation method prepares the immersion photoresist by polymerization reaction, and adds fluorine-containing monomers in the later stage of the reaction, so that the generated immersion photoresist resin contains a large amount of fluorine-free resin (equivalent to the main resin) and a small amount of fluorine-containing resin, so that it can be directly used for the preparation of immersion photoresist. By controlling the amount of fluorine-containing monomers, the proportion of fluorine-containing resin in the immersion photoresist can be well controlled. Because most of the structures of the fluorine-containing resin and the non-fluorine-containing resin in the immersion photoresist resin obtained are similar, there is no problem of mismatch between the two. The immersion photoresist is prepared by the immersion photoresist resin of the present application, and the fluorine-containing resin is enriched on the surface during the immersion photolithography process to form an isolation layer, which can effectively inhibit the effective water-soluble components such as photoacid generators in the photoresist from entering deionized water, so that the lines of the pattern formed by the photoresist are clear and there is no colloid peeling phenomenon. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Photolithography topography of Example 1;

[0013] Figure 2 Photolithography topography of Example 2;

[0014] Figure 3 Photolithography topography of Example 3;

[0015] Figure 4 Photolithography topography of Example 4;

[0016] Figure 5 Lithography morphology of Comparative Example 1;

[0017] Figure 6 Photolithography morphology image of Comparative Example 2. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In order to prevent the transfer of photoresist components to the aqueous medium during the immersion photolithography process, the prior art often adds a small amount of fluorine-containing resin to conventional photoresist. The fluorine-containing resin polymerizes on the surface of the photoresist to form a water-resistant coating, which plays a role in preventing the transfer of photoresist components to the aqueous medium. For example, CN112898185A discloses a fluorine-containing compound for immersion photoresist. The fluorine-containing compound is added to the conventional photoresist, and the fluorine-containing photoresist is prepared after being fully stirred. The fluorine-containing compound plays a top coating role to prevent the transfer of photoresist components to the aqueous medium. CN117683157A, CN117683157A, etc. disclose similar fluorine-containing resins and immersion photoresists. However, the main component of conventional photoresist is the main resin. Mixing the fluorine-containing resin with the main resin may cause the two resins to not match, which affects the morphology of the photoresist. Mixing the two resins also makes the photoresist formula more complicated, increasing the process difficulty. The present invention provides a resin for immersion photoresist, a preparation method and immersion photoresist from different perspectives.

[0020] An embodiment of the present invention provides a method for preparing a resin for immersion photoresist, the method comprising:

[0021] Add an initiator, ethyl cyclopentanol methacrylate, hydroxyadamantyl methacrylate, butyrolactone methacrylate and a reaction solvent into a reaction container, heat to 60°C to 80°C for reaction, and after reacting for 6h to 8h, add a fluorine-containing monomer into the reaction container, and continue heating to react for 30min to 60min;

[0022] After the reaction is completed, a precipitation treatment is performed using an organic solvent to obtain a resin for immersion photoresist.

[0023] In the preparation method, when preparing the resin for immersion photoresist, ethyl cyclopentanol methacrylate, hydroxyadamantyl methacrylate, methyl butyrolactone methacrylate and other non-fluorine-containing monomers are first polymerized under initiator and heating conditions to generate resin, and then a certain amount of fluorine-containing monomers are added in the later stage of the reaction, and the reaction is continued to obtain a partial fluorine-containing resin. The immersion photoresist resin prepared in this way includes the fluorine-containing resin in the prior art and the main resin. When preparing the immersion photoresist, this immersion photoresist resin can be used. The immersion photoresist resin obtained in this way also does not have the problem of mismatch between the fluorine-containing resin and the main resin in the prior art.

[0024] In addition, the prior art adds fluorine-containing monomers at the beginning of the polymerization reaction when preparing fluorine-containing resins. These fluorine-containing monomers compete with main monomers such as methyl methacrylate ethyl cyclopentanol during the polymerization process, affecting the reactivity ratio between each other. The fluorine-containing monomers will be randomly distributed in the polymer chain. When added to the photoresist, it is not conducive to the enrichment of the fluorine-containing resin component on the surface of the silicon wafer, and it is difficult to form a uniform water-resistant layer, which is not conducive to the photolithography process and will affect the clarity of the photolithography pattern. The present application can obtain a fluorine-containing resin of a suitable proportion by adding an appropriate amount of fluorine-containing monomers in the later stage of the reaction, and at the same time, the fluorine-containing monomers are distributed on the surface of the fluorine-containing resin. In the photoresist preparation process, the fluorine-containing resin can form a uniform and dense water-resistant layer, which better plays the role of inhibiting the components in the photoresist from entering the water. At the same time, the molecular weight distribution of the immersion photoresist resin of the present application is narrow, and it is easier to spin-coat on the surface of the silicon wafer. After the immersion photoresist resin of the present application is used for the immersion photoresist process, the graphic lines of the obtained photoresist are clearer.

[0025] In some embodiments, the initiator is one or both of azobisisobutyronitrile and azobisisoheptanenitrile.

[0026] In some embodiments, the reaction solvent is one or both of propylene glycol methyl ether acetate and methyl ethyl ketone.

[0027] In some embodiments, the fluorine-containing monomer is one or more of tridecafluorooctyl acrylate, perfluoroacrylate, perfluorooctyl ethyl acrylate, trifluoroethyl acrylate, trifluoroethyl methacrylate, and 2-(perfluorohexyl)ethyl methacrylate.

[0028] In some embodiments, the weight ratio of the initiator, ethyl cyclopentanol methacrylate, hydroxyadamantyl methacrylate, butyrolactone methacrylate and the fluorine-containing monomer added to the reaction container is 0.3-1: 30-50: 20-40: 20-40: 10-30. At this ratio, the reaction can make full use of each reaction reagent to generate an immersion photoresist resin with a narrower molecular weight distribution and a degree of polymerization that meets expectations, and the proportion of the fluorine-containing resin therein is about 2% to 7%. Preferably, the weight ratio of the initiator, ethyl cyclopentanol methacrylate, hydroxyadamantyl methacrylate, butyrolactone methacrylate and the fluorine-containing monomer added to the reaction container is 0.3-1: 30-50: 20-40: 20-40: 10-20, and the proportion of the fluorine-containing resin at this ratio is about 2% to 5%, and the linearity of the final photolithographic pattern is better.

[0029] In some embodiments, the weight of the reaction solvent added to the reaction container accounts for 20% to 40% of the total weight of all materials added.

[0030] In some embodiments, the reaction temperature is controlled to be 60°C to 80°C for reaction. After the reaction has been in progress for 6 to 8 hours, a fluorine-containing monomer is added to the reaction vessel, and the reaction temperature is continued to be controlled to be 60°C to 80°C, and the reaction is continued for 30 to 60 minutes. The reaction at 60°C to 80°C for 6 to 8 hours can basically complete the reaction of the previously added monomer. At this time, the fluorine-containing monomer is added, and the reaction is continued at 60°C to 80°C for 30 minutes to 60 minutes, so that the fluorine-containing monomer can be continuously added to part of the precursor resin to obtain an appropriate amount of fluorine-containing resin.

[0031] The embodiment of the present invention provides an immersion photoresist resin, which is prepared by the above-mentioned immersion photoresist resin preparation method, wherein the proportion of fluorine-containing monomer is 2% to 8%. The immersion photoresist resin has the dual functions of main resin and fluorine-containing resin, making the formulation of the photoresist simpler and having better effect.

[0032] An embodiment of the present invention provides an immersion photoresist, which includes: the aforementioned immersion photoresist resin, a photoacid generator, a quencher, and an organic solvent.

[0033] In some embodiments, the photoacid generator is one or more of diazonium salts, sulfonium salts, iodonium salts, sulfonyldiazomethane, imide sulfonate, nitrobenzylbenzenesulfonate, and sulfonic acid oxime esters.

[0034] In some embodiments, the photoacid generator is one of triphenylsulfonium trifluoromethanesulfonate, N-hydroxysuccinimide methanesulfonate, and triphenylsulfonium p-toluenesulfonate.

[0035] In some embodiments, the quencher is one or more of an amine compound, a sulfonate or a carboxylate, preferably at least one of the following compounds: Quencher 1 、 Quencher 2.

[0036] In some embodiments, the organic solvent is at least one of propylene glycol methyl ether acetate and propylene glycol methyl ether.

[0037] The immersion photoresist of the invention is suitable for immersion photolithography technology, and the image lines after exposure and development are clear and the resolution is high.

[0038] Example 1

[0039] This embodiment provides a preparation method of an immersion photoresist resin and an immersion photoresist resin. The proportion of the fluorine-containing resin in the immersion photoresist resin is 2%.

[0040] In a 500mL three-necked flask, add 0.3g of azobisisobutyronitrile, 30g of ethyl cyclopentanol methacrylate, 20g of hydroxyadamantane methacrylate, 20g of methyl butyrolactone methacrylate and 14g of propylene glycol methyl ether acetate and mix thoroughly. After nitrogen is introduced into the mixed liquid for deoxygenation for 30 minutes, place it in a constant temperature water bath at 70°C for heating and reflux reaction for 6 hours. Add 10g of 13-fluorooctyl acrylate and continue to react at 70°C for 30 minutes. After the reaction is completed, the reaction solution is added dropwise to methanol for precipitation, and the precipitate is the resin for immersion photoresist.

[0041] Example 2

[0042] This embodiment provides a method for preparing an immersion photoresist resin and the immersion photoresist resin. The proportion of the fluorine-containing resin in the immersion photoresist resin is 4%.

[0043] In a 500mL three-necked flask, add 0.6g of azobisisoheptanenitrile, 40g of ethyl cyclopentanol methacrylate, 30g of hydroxyadamantane methacrylate, 30g of butyrolactone methacrylate and 20g of propylene glycol methyl ether acetate and mix thoroughly. After nitrogen is introduced into the mixed liquid for deoxygenation for 30 minutes, place it in a constant temperature water bath at 60°C for heating and reflux reaction for 7 hours. Add 15g of perfluoroacrylate and continue to react at 60°C for 45 minutes. After the reaction is completed, the reaction solution is added dropwise to methanol for precipitation, and the precipitate is the resin for immersion photoresist.

[0044] Example 3

[0045] This embodiment provides a method for preparing an immersion photoresist resin and the immersion photoresist resin. The proportion of the fluorine-containing resin in the immersion photoresist resin is 5%.

[0046] In a 500mL three-necked flask, add 1g of azobisisoheptanenitrile, 50g of ethyl cyclopentanol methacrylate, 40g of hydroxyadamantane methacrylate, 40g of methyl butyrolactone methacrylate and 28g of propylene glycol methyl ether acetate and mix thoroughly. After nitrogen is introduced into the mixed liquid for deoxygenation for 30 minutes, place it in a constant temperature water bath at 80°C for heating and reflux reaction for 8 hours. Add 20g of trifluoroethyl methacrylate and continue to react at 80°C for 60 minutes. After the reaction is completed, the reaction solution is added dropwise to methanol for precipitation, and the precipitate is the resin for immersion photoresist.

[0047] Example 4

[0048] This embodiment provides a preparation method of an immersion photoresist resin and an immersion photoresist resin. The proportion of the fluorine-containing resin in the immersion photoresist resin is 7%.

[0049] In a 500mL three-necked flask, add 1g of azobisisoheptanenitrile, 50g of ethyl cyclopentanol methacrylate, 40g of hydroxyadamantane methacrylate, 40g of butyrolactone methacrylate and 28g of propylene glycol methyl ether acetate and mix them thoroughly. After nitrogen is introduced into the mixed liquid for deoxygenation for 30 minutes, place it in a constant temperature water bath at 80°C for heating and reflux reaction for 8 hours. Add 30g of trifluoroethyl methacrylate and continue to react at 80°C for 60 minutes. After the reaction is completed, the reaction solution is added dropwise to methanol for precipitation, and the precipitate is the resin for immersion photoresist.

[0050] Comparative Example 1

[0051] In this comparative example, no fluorine-containing monomer was added to prepare the obtained resin.

[0052] 0.3 g of azobisisobutyronitrile, 30 g of ethyl cyclopentanol methacrylate, 20 g of hydroxyadamantyl methacrylate, 20 g of butyrolactone methacrylate and 14 g of propylene glycol methyl ether acetate were added to a 500 mL three-necked flask and mixed thoroughly. Nitrogen was introduced into the mixed liquid for deoxygenation for 30 min, and then placed in a constant temperature water bath at 70° C. for heating and reflux reaction for 7 h. After the reaction was completed, the reaction solution was added dropwise to methanol for precipitation, and the precipitate was taken to obtain the resin.

[0053] Comparative Example 2

[0054] In this comparative example, no fluorine-containing monomer was added to prepare a resin, and a fluorine-containing resin was added to the resin to obtain a mixed resin.

[0055] 0.3 g of azobisisobutyronitrile, 30 g of ethyl cyclopentanol methacrylate, 20 g of hydroxyadamantyl methacrylate, 20 g of butyrolactone methacrylate and 14 g of propylene glycol methyl ether acetate were added to a 500 mL three-necked flask and mixed thoroughly. Nitrogen was introduced into the mixed liquid for deoxygenation for 30 min, and then placed in a constant temperature water bath at 70° C. for heating and reflux reaction for 7 h. After the reaction was completed, the reaction solution was added dropwise to methanol for precipitation, and the precipitate was taken to obtain the resin.

[0056] Another fluorine-containing resin is added to the obtained resin. The fluorine-containing resin is obtained according to the preparation method in CN 112898185A. The proportion of the added fluorine-containing resin is 2%.

[0057] The ratio of fluorine-containing resin in the above embodiment was detected by 400MHZ nuclear magnetic resonance instrument. 13 The weight average molecular weight and molecular weight distribution of the resins synthesized in Examples 1 to 4, Comparative Examples 1 and 2 were measured by gel chromatography, and the results are shown in Table 1 below.

[0058] Resins of Examples 1 to 4, Comparative Examples 1 and 2 were taken respectively and subjected to immersion photolithography. The photoresist formulation was: 1.5 g of resin (resin in each example or comparative example), 0.1 g of triphenylsulfonium trifluoromethanesulfonate, 0.06 g of quencher 1, 30 g of propylene glycol methyl ether acetate, and 10 g of propylene glycol methyl ether. The static contact angle of each formulation was tested, and the results are shown in Table 1 below.

[0059] Contact angle test method: The polymer solution was coated on an 8-inch silicon wafer, and PAB was applied at 100°C for 60 seconds to form a 100nm thick coating. The dynamic contact angle was tested using an SDC-100 contact angle meter. The coating was developed in a TMAH aqueous solution for 60 seconds, rinsed with deionized water for 30 seconds, and the static contact angle after development was tested.

[0060] Photolithography process conditions: 110℃ baking for 2min, exposure energy: 45mj / cm 2 , development time 60s. The morphological effects of each photoresist are as follows Figure 1-Figure 6 shown.

[0061] Table 1

[0062]

[0063] It can be seen from the results in the table that the immersion photoresist resin containing a certain proportion of fluorine-containing resin can be obtained through the preparation method of the immersion photoresist resin of the present application. The molecular weight distribution of the immersion photoresist resin is narrow. When used for photoresist preparation, the photoresist contact angle is large, indicating that it has good hydrophobic properties and can effectively prevent the effective components in the photoresist from entering the water. By comparing Example 1 and Example 4, it can be seen that when preparing the immersion photoresist resin, as the proportion of the fluorine-containing resin part in the obtained immersion photoresist resin increases, the photoresist contact angle tends to increase. Figure 1-Figure 4 It can be seen that by using the immersion photoresist resin of the present application to prepare the photoresist, clearer photoresist lines are obtained after the photolithography process, which is significantly better than that of Comparative Example 1; the corresponding lines of Examples 1 to 3 are significantly better than those of Example 4 and Comparative Examples 1 and 2, indicating that the effects of Examples 1 to 3 are better.

[0064] In summary, the immersion photoresist resin containing 2% to 7% fluorine-containing resin can be obtained by the preparation method of the immersion photoresist resin of the present application, and the immersion photoresist resin can be directly used to prepare the immersion photoresist, wherein the fluorine-containing resin part can play a good role as a water-resistant coating, so there is no need to add other water-resistant coating components. The use of the immersion photoresist resin to prepare a photoresist can obtain a photolithography pattern with clearer and smoother lines.

[0065] It is understandable that those skilled in the art can, under the guidance of the above embodiments, combine various implementation methods in the above embodiments to obtain technical solutions of multiple implementation methods.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a resin for immersion photoresist, characterized in that: The method comprises: Add an initiator, ethyl cyclopentanol methacrylate, hydroxyadamantyl methacrylate, butyrolactone methacrylate and a reaction solvent into a reaction container, heat to 60°C to 80°C for reaction, and after reacting for 6h to 8h, add a fluorine-containing monomer into the reaction container, and continue heating to react for 30min to 60min; After the reaction is completed, a precipitation treatment is performed using an organic solvent to obtain a resin for immersion photoresist.

2. The preparation method according to claim 1, characterized in that The initiator is one or both of azobisisobutyronitrile and azobisisoheptanenitrile.

3. The preparation method according to claim 1, characterized in that: The reaction solvent is one or both of propylene glycol methyl ether acetate and methyl ethyl ketone.

4. The preparation method according to claim 1, characterized in that: The fluorine-containing monomer is one or more of tridecafluorooctyl acrylate, perfluoroacrylate, perfluorooctyl ethyl acrylate, trifluoroethyl acrylate, trifluoroethyl methacrylate, and 2-(perfluorohexyl)ethyl methacrylate.

5. The preparation method according to claim 1, characterized in that: The weight ratio of the initiator, ethylcyclopentanol methacrylate, hydroxyadamantyl methacrylate, butyrolactone methacrylate and fluorine-containing monomer added into the reaction container is 0.3-1:30-50:20-40:20-40:10-30.

6. The preparation method according to claim 1, characterized in that: The weight of the reaction solvent added to the reaction container accounts for 20% to 40% of the total weight of all materials added.

7. A resin for immersion photoresist obtained by the preparation method according to any one of claims 1 to 6, characterized in that: The proportion of the fluorine-containing monomer in the immersion photoresist resin is 2% to 8%.

8. An immersion photoresist, characterized in that: The immersion photoresist comprises: the immersion photoresist resin according to claim 7, a photoacid generator, a quencher, and an organic solvent.

9. The immersion photoresist according to claim 8, characterized in that The photoacid generator is one or more of diazonium salts, sulfonium salts, iodonium salts, sulfonyldiazomethane, imidesulfonate, nitrobenzylbenzenesulfonate, and sulfonic acid oxime esters.

10. The immersion photoresist according to claim 8, characterized in that The quencher is one or more of an amine compound, a sulfonate or a carboxylate, and the organic solvent is at least one of propylene glycol methyl ether acetate and propylene glycol methyl ether.

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