BCB photoresist and preparation method thereof

Abstract

The invention discloses a BCB photoresist and a preparation method thereof, and belongs to the technical field of photoresists. Comprising the following raw materials in parts by weight: 60-70 parts of modified BCB resin, 20-30 parts of a solvent, 1-3 parts of anthraquinone-2-sodium sulfonate and 5-9 parts of triallyl isocyanurate. Wherein the modified BCB resin is prepared from the following raw materials: 4-vinyl benzocyclobutene, p-divinyl benzene, an RAFT (Reversible Addition-Fragmentation Chain Transfer) reagent and an anti-impact modifier, and the anti-impact modifier not only improves the impact resistance of the cured photoresist, but also has photosensitivity and broadens the ultraviolet response range; sodium anthraquinone-2-sulfonate is added into the raw materials of the BCB photoresist as a nano sensitizer, so that the ultraviolet absorption is further enhanced, and the developing contrast is improved; in conclusion, the photoresist prepared by the invention has both impact resistance and photosensitivity, is stable in performance, and has important application value in the technical field of photoresist.

Description

Technical Field

[0001] This invention belongs to the field of photoresist technology, specifically relating to a BCB photoresist and its preparation method. Background Technology

[0002] With the rapid development of the microelectronics industry towards miniaturization, high speed, and high density, increasingly stringent requirements are being placed on the performance of integrated circuit manufacturing materials. Among many key materials, photoresist, as one of the core materials that determines the precision and performance of chip manufacturing, has always been a focus of industry attention in terms of technological innovation and performance improvement.

[0003] Currently, mainstream photoresist systems are mainly based on phenolic resins, polymethyl methacrylate (PMMA), or chemically amplified resists. These materials are prone to thermal decomposition or glass transition at high temperatures, leading to pattern collapse. Especially in back-end processes, when the processing temperature exceeds 250°C, the Young's modulus of traditional photoresists drops sharply, failing to meet the stringent thermal stability requirements of wafer-level packaging or through-silicon via (TSV) processes. Furthermore, the films formed after curing conventional photoresists often exhibit high dielectric constants, causing severe parasitic capacitance effects in high-frequency signal transmission scenarios, thus hindering the development of high-performance devices.

[0004] Benzocyclobutene (BCB) emerged in this context. Due to its highly stable benzene ring structure, BCB resin theoretically possesses excellent thermal stability and low dielectric properties, gradually becoming a key material in semiconductor packaging and microelectronics manufacturing. However, in the early days, the application of non-photosensitive BCB resin in microelectronic packaging required coating its surface with a layer of photoresist to etch complex circuit patterns, followed by a series of cumbersome processes including exposure, etching, and photoresist removal. This processing method was not only complex and prone to introducing defects during operation, leading to reduced yield, but also required numerous pieces of equipment with high maintenance costs, significantly increasing product production costs.

[0005] With continuous technological advancements, photosensitive BCB resins have been developed and applied. Photosensitive BCB resins can be directly exposed, exhibiting significant solubility differences between exposed and unexposed areas. After solvent development, complex circuit patterns can be easily obtained, eliminating the need for additional photoresist coating and related processing steps. This provides a simpler and more efficient process for precise coating fabrication, leading to its increasingly widespread use. However, cured BCB resin films often exhibit high brittleness and weak impact resistance. Under mechanical stress (such as cutting and grinding), they are prone to microcracks, affecting the long-term reliability of the packaging structure. Therefore, it is urgent to solve this problem to meet the higher demands of the photoresist technology field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a BCB photoresist and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A BCB photoresist comprises the following raw materials in parts by weight: 60-70 parts modified BCB resin, 20-30 parts solvent, 1-3 parts sodium anthraquinone-2-sulfonate, and 5-9 parts triallyl isocyanurate.

[0009] As a further technical solution, the modified BCB resin is prepared through the following steps:

[0010] Add 4-vinylbenzocyclobutene, p-divinylbenzene, impact modifier, RAFT reagent, and toluene to a dry three-necked flask equipped with a reflux condenser. Purge the air from the apparatus with nitrogen, heat the oil bath to 60-90°C, and stir the reaction for 8-12 hours. After the reaction is complete, cool the system to room temperature, precipitate the obtained polymer solution in methanol, filter, wash, and vacuum dry to obtain the modified BCB resin.

[0011] As a further technical solution, the ratio of the amounts of 4-vinylbenzocyclobutene, p-divinylbenzene, impact modifier, and RAFT reagent is 100g:4-8g:5-10g:0.2-0.4g.

[0012] As a further technical solution, the RAFT reagent is one of benzoyl peroxide and azobisisobutyronitrile.

[0013] As a further technical solution, the impact modifier is prepared through the following steps:

[0014] A1. In a three-necked flask, first add 2,2',4,4'-tetrahydroxybenzophenone, dodecyl chloride and toluene. Stir and mix thoroughly, then purge the air from the apparatus with nitrogen. Subsequently, add sodium hydroxide solution (12% by mass) dropwise to the three-necked flask using a constant pressure dropping funnel. Heat the apparatus until the temperature reaches 65-70℃, maintain this temperature, and stir the reaction for 4-5 hours. After the reaction is complete, perform post-processing to obtain the initial product.

[0015] A2. In a three-necked flask, first add the initial product and toluene, stir and mix, then add allyl chloride under ice bath conditions of 0-5℃, and then add sodium carbonate to adjust the pH of the reaction system to 8-9. Remove the ice bath, and stir the reaction at room temperature for 8-9 hours. After the reaction is complete, the impact modifier is obtained through post-processing.

[0016] As a further technical solution, in step A1, the ratio of the amounts of 2,2',4,4'-tetrahydroxybenzophenone, dodecyl chloride and sodium hydroxide solution is 25.7-26.9 g: 20.4 g: 30 mL.

[0017] As a further technical solution, the ratio of the amount of initial product to allyl chloride in step A2 is 42.2-43.5g:7.6g.

[0018] The reaction formula for preparing the impact modifier of this invention is as follows:

[0019]

[0020] In the preparation of impact modifiers, the following two points need to be noted: First, in step A1, the reaction between 2,2',4,4'-tetrahydroxybenzophenone and chlorododecane requires strict control of their molar ratio to be close to 1:1, with the former in excess, to reduce side reactions. Second, in step A2, temperature and pH need to be strictly controlled so that the phenolic hydroxyl group reacts with the chlorine group first, thereby retaining the epoxy group. Similarly, the molar ratio of the initial product to allyl chloride needs to be strictly controlled to be close to 1:1, with the former in excess, to reduce side reactions.

[0021] As can be seen from the above reaction formula, the prepared impact modifier incorporates aliphatic long chains. In this long-chain structure, the C-C single bonds can rotate freely, thereby reducing the rigidity of the molecular chain, absorbing external force energy, and improving the impact resistance of the photoresist after curing. In addition, a benzophenone structure is also introduced. This structure can act as a photosensitizer, which, compared with traditional photosensitizers, broadens the response range to ultraviolet light and solves the problem of low photosensitivity. Finally, the introduced unsaturated double bonds enable the impact modifier to participate in the polymerization reaction of BCB resin, resulting in better effects and more stable performance compared to directly adding modifiers.

[0022] As a further technical solution, the solvent is a mixture of propylene glycol methyl ether acetate and γ-butyrolactone in a mass ratio of 6:4.

[0023] This invention also provides a method for preparing BCB photoresist, comprising the following steps:

[0024] The modified BCB resin was added to the solvent and stirred at 50-55℃ for 1-2 hours to dissolve the resin. Then, sodium anthraquinone-2-sulfonate and triallyl isocyanurate were added in sequence, and stirring was continued for 1-2 hours. The mixture was then ultrasonically dispersed for 30-60 minutes and filtered to obtain the BCB photoresist.

[0025] As a further technical solution, the stirring speed is 300-500 r / min.

[0026] As a further technical solution, the pore size of the filter membrane used for filtration is 0.3-1μm.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention has a self-made impact modifier and modifies BCB resin, which not only improves the impact resistance of the photoresist after curing, but also has photosensitivity and broadens the ultraviolet response range.

[0029] 2. In this invention, sodium anthraquinone-2-sulfonate is added as a nano-sensitizer to further enhance ultraviolet absorption and improve development contrast;

[0030] In summary, the photoresist prepared by this invention has both impact resistance and photosensitivity, and its performance is stable, making it of significant application value in the field of photoresist technology. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] Preparation of impact modifiers:

[0034] A1. In a three-necked flask, first add 25.7g of 2,2',4,4'-tetrahydroxybenzophenone, 20.4g of chlorododecane and 150mL of toluene. After stirring and mixing evenly, nitrogen gas is introduced to purge the air from the apparatus. Then, using a constant pressure dropping funnel, 30mL of sodium hydroxide solution (mass fraction 12%) is added dropwise to the three-necked flask. The apparatus is heated until the temperature reaches 65℃, and this temperature is maintained. The reaction is stirred for 4 hours. After the reaction is complete, the liquid is separated, washed several times with deionized water, dried with anhydrous sodium sulfate, filtered, and distilled under reduced pressure to obtain the primary product.

[0035] A2. In a three-necked flask, 42.2 g of the initial product and 150 mL of toluene were added and stirred. After mixing, 7.6 g of allyl chloride was added under ice bath conditions at 0 °C. Sodium carbonate was then added to adjust the pH of the reaction system to 8. The ice bath was removed, and the reaction was stirred at room temperature for 8 h until the reaction was complete. Dilute hydrochloric acid (18% by mass) was added dropwise to adjust the solution to neutral. The solution was extracted by separation, and the organic phase was dried with anhydrous sodium sulfate, filtered, rotary evaporated, washed several times with methanol, filtered under vacuum, and dried to obtain the shock modifier.

[0036] Preparation of modified BCB resin:

[0037] 100g of 4-vinylbenzocyclobutene, 4g of p-divinylbenzene, 5g of impact modifier, 0.2g of benzoyl peroxide, and 150mL of toluene were added to a dry three-necked flask equipped with a reflux condenser. Nitrogen gas was introduced to purge air from the apparatus, and the oil bath temperature was raised to 60°C. The mixture was stirred and reacted for 8 hours. After the reaction was completed, the system was cooled to room temperature. The resulting polymer solution was precipitated in methanol, filtered, washed, and dried under vacuum to obtain the modified BCB resin.

[0038] A method for preparing BCB photoresist includes the following steps:

[0039] 60g of modified BCB resin was added to 20g of solvent (12g of propylene glycol methyl ether acetate and 8g of γ-butyrolactone). The mixture was stirred at 300r / min for 1h at 50℃ to dissolve the resin. Then, 1g of sodium anthraquinone-2-sulfonate and 5g of triallyl isocyanurate were added sequentially. The mixture was stirred for another 1h and ultrasonically dispersed for 30min. The mixture was then filtered (the pore size of the filter membrane used was 1μm) to obtain the BCB photoresist.

[0040] Example 2

[0041] Preparation of impact modifiers:

[0042] A1. In a three-necked flask, first add 26.9 g of 2,2',4,4'-tetrahydroxybenzophenone, 20.4 g of chlorododecane, and 150 mL of toluene. After stirring and mixing evenly, purge the air from the apparatus with nitrogen gas. Then, use a constant pressure dropping funnel to add 30 mL of sodium hydroxide solution (mass fraction 12%) dropwise to the three-necked flask. Heat the apparatus until the temperature reaches 70 °C, maintain this temperature, and stir the reaction for 5 hours. After the reaction is complete, separate the liquids, wash several times with deionized water, dry the organic phase with anhydrous sodium sulfate, filter, and distill under reduced pressure to obtain the primary product.

[0043] A2. In a three-necked flask, 43.5 g of the initial product and 150 mL of toluene were added and stirred. After mixing, 7.6 g of allyl chloride was added under ice bath conditions at 5 °C. Sodium carbonate was then added to adjust the pH of the reaction system to 9. The ice bath was removed, and the reaction was stirred at room temperature for 9 h until the reaction was complete. Dilute hydrochloric acid (18% by mass) was added dropwise to adjust the solution to neutral. The solution was extracted by separation, and the organic phase was dried with anhydrous sodium sulfate, filtered, rotary evaporated, washed several times with methanol, filtered under vacuum, and dried to obtain the shock modifier.

[0044] Preparation of modified BCB resin:

[0045] 100g of 4-vinylbenzocyclobutene, 6g of p-divinylbenzene, 7.5g of impact modifier, 0.3g of azobisisobutyronitrile, and 150mL of toluene were added to a dry three-necked flask equipped with a reflux condenser. Nitrogen gas was introduced to purge the air from the apparatus, and the oil bath temperature was raised to 75°C. The mixture was stirred and reacted for 10 hours. After the reaction was completed, the system was cooled to room temperature. The resulting polymer solution was precipitated in methanol, filtered, washed, and dried under vacuum to obtain the modified BCB resin.

[0046] A method for preparing BCB photoresist includes the following steps:

[0047] 70g of modified BCB resin was added to 30g of solvent (18g of propylene glycol methyl ether acetate and 12g of γ-butyrolactone were compounded), and stirred at 500r / min for 2h at 55℃ to dissolve the resin. Then, 2g of sodium anthraquinone-2-sulfonate and 7g of triallyl isocyanurate were added in sequence, and stirring was continued for 2h. The mixture was then ultrasonically dispersed for 45min and filtered (the pore size of the filter membrane used was 1μm) to obtain BCB photoresist.

[0048] Example 3

[0049] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the modified BCB resin is prepared through the following steps:

[0050] 100g of 4-vinylbenzocyclobutene, 8g of p-divinylbenzene, 10g of impact modifier, 0.4g of azobisisobutyronitrile, and 150mL of toluene were added to a dry three-necked flask equipped with a reflux condenser. Nitrogen gas was introduced to purge the air from the apparatus. The oil bath temperature was raised to 90℃, and the reaction was stirred for 12h. After the reaction was completed, the system was cooled to room temperature. The obtained polymer solution was precipitated in methanol, filtered, washed, and vacuum dried to obtain the modified BCB resin.

[0051] A method for preparing BCB photoresist includes the following steps:

[0052] 70g of modified BCB resin was added to 30g of solvent (18g of propylene glycol methyl ether acetate and 12g of γ-butyrolactone were compounded), and stirred at 500r / min for 2h at 55℃ to dissolve the resin. Then, 3g of sodium anthraquinone-2-sulfonate and 9g of triallyl isocyanurate were added in sequence, and stirring was continued for 2h. The mixture was then ultrasonically dispersed for 60min and filtered (the pore size of the filter membrane used was 1μm) to obtain BCB photoresist.

[0053] Comparative Example 1

[0054] The only difference between this comparative example and Example 3 is that in this comparative example, an equal amount of benzoin ether is used as a photosensitizer to replace the impact modifier, and BCB photoresist is directly prepared as a raw material (without modifying the BCB resin).

[0055] Comparative Example 2

[0056] The only difference between this comparative example and Example 3 is that in this comparative example, the BCB resin is not modified, and an equal amount of ordinary BCB resin is used to replace the modified BCB resin to prepare BCB photoresist.

[0057] The following performance tests were conducted on Examples 1, 2, and 3, and Comparative Examples 1 and 2:

[0058] The impact resistance of the cured specimens was determined using the GB / T 1732-93 standard (the impact resistance is expressed as the maximum impact height).

[0059] The exposure energy of the sample was determined using an ultraviolet exposure machine;

[0060] The results of the performance tests are shown in Table 1:

[0061] Table 1

[0062]

[0063]

[0064] As can be seen from the table above, the photoresist prepared in the embodiments of the present invention has higher impact resistance and photosensitivity than the comparative example. Therefore, the present invention has important application value in the field of photoresist technology.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A BCB photoresist, characterized in that, The raw materials include the following parts by weight: 60-70 parts modified BCB resin, 20-30 parts solvent, 1-3 parts sodium anthraquinone-2-sulfonate, and 5-9 parts triallyl isocyanurate.

2. The BCB photoresist according to claim 1, characterized in that, The modified BCB resin is prepared by the following steps: Add 4-vinylbenzocyclobutene, p-divinylbenzene, impact modifier, RAFT reagent, and toluene to a dry three-necked flask equipped with a reflux condenser. Purge the air from the apparatus with nitrogen, heat the oil bath to 60-90°C, and stir the reaction for 8-12 hours. After the reaction is complete, cool the system to room temperature, precipitate the obtained polymer solution in methanol, filter, wash, and vacuum dry to obtain the modified BCB resin.

3. The BCB photoresist according to claim 2, characterized in that, The ratio of the amounts of 4-vinylbenzocyclobutene, p-divinylbenzene, impact modifier, and RAFT reagent is 100g:4-8g:5-10g:0.2-0.4g.

4. The BCB photoresist according to claim 2, characterized in that, The impact modifier is prepared by the following steps: A1. In a flask, add 2,2',4,4'-tetrahydroxybenzophenone, dodecyl chloride and toluene, stir, then purge with nitrogen gas, add sodium hydroxide solution, and react at 65-70℃ for 4-5 hours. The reaction is complete, and the initial product is obtained. A2. In a flask, add the initial product and toluene, stir, and then add allyl chloride under ice bath conditions at 0-5℃. Add sodium carbonate to adjust the pH to 8-9, remove the ice bath, and stir the reaction at room temperature for 8-9 hours. The reaction is complete, and the shock modifier is obtained.

5. The BCB photoresist according to claim 4, characterized in that, In step A1, the ratio of 2,2',4,4'-tetrahydroxybenzophenone, dodecyl chloride, and sodium hydroxide solution is 25.7-26.9 g: 20.4 g: 30 mL.

6. The BCB photoresist according to claim 4, characterized in that, In step A2, the ratio of the initial product to allyl chloride is 42.2-43.5 g: 7.6 g.

7. The BCB photoresist according to claim 2, characterized in that, The RAFT reagent is one of benzoyl peroxide and azobisisobutyronitrile.

8. The BCB photoresist according to claim 1, characterized in that, The solvent is a mixture of propylene glycol methyl ether acetate and γ-butyrolactone in a mass ratio of 6:

4.

9. A method for preparing a BCB photoresist, used to prepare the BCB photoresist according to any one of claims 1-8, characterized in that, Includes the following steps: The modified BCB resin was added to the solvent and stirred at 50-55℃ for 1-2 hours to dissolve the resin. Then, sodium anthraquinone-2-sulfonate and triallyl isocyanurate were added in sequence, and stirring was continued for 1-2 hours. The mixture was then ultrasonically dispersed and filtered to obtain the BCB photoresist.

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