Polyimide photoresist composition and application thereof

Abstract

The invention provides a polyimide photoresist composition. The polyimide photoresist composition comprises 1 wt%-70 wt% of a polyimide precursor; 0.1 wt% to 10 wt% of a photoinitiator; from 1 wt% to 10 wt% of an ester monomer; the solvent comprises ethyl lactate and gamma valerolactone, and the weight ratio of the ethyl lactate to the gamma valerolactone is between 1: 9 and 9: 1.

Description

Technical Field

[0001] The present invention relates to a polyimide photoresist composition and its use, and particularly to a polyimide photoresist composition using ethyl lactate and γ-valerolactone as solvents and its use. Background Art

[0002] Currently, common photoresist agents for polyimide photoresists on the market use N-methylpyrrolidone (NMP) and ethyl lactate (EL) as solvents.

[0003] The reason why NMP is used as a solvent for polyimide photoresists is that NMP has high boiling point and flash point, and has good solubility for polyimide precursors. However, NMP is environmentally toxic. Since 2014, the European Union has begun to restrict the use of NMP in chemicals. In May 2020, REACH added regulations that the concentration of NMP in itself or in products shall not be higher than 0.3%. Therefore, major electronics manufacturers have also begun to gradually reduce the use of chemicals containing NMP solvent.

[0004] In view of this, there is an urgent need to develop a novel polyimide photoresist composition that uses bio-based and environmentally friendly solvents to replace NMP solvent to solve the above problems. Summary of the Invention

[0005] In view of this, the present invention provides a polyimide photoresist composition and its use, in order to at least partially solve the above technical problems. Thus, the technical solutions provided by the present invention are as follows.

[0006] The main object of the present invention is to provide a polyimide photoresist composition that uses bio-based and environmentally friendly solvents to replace NMP solvent.

[0007] The polyimide photoresist composition of the present invention includes: 1 wt% to 70 wt% of a polyimide precursor; 0.1 wt% to 10 wt% of a photoinitiator; 1 wt% to 10 wt% of an ester monomer; and the balance of a solvent, wherein the solvent includes ethyl lactate and γ-valerolactone, and the weight ratio of ethyl lactate to γ-valerolactone is between 1:9 and 9:1.

[0008] In the composition of the present invention, the solvents used are ethyl lactate (EL) and γ-valerolactone (GVL), which are bio-based and environmentally friendly solvents. In particular, the composition of the present invention does not include N-methylpyrrolidone. In addition, by using a combination of ethyl lactate and γ-valerolactone as solvents, the polyimide photoresist composition of the present invention has excellent exposure latitude and can improve the cyclization rate of polyimide precursors at low temperatures. Furthermore, the polyimide cured film formed using the polyimide photoresist composition of the present invention has good mechanical properties and can be applied to semiconductor devices in different forms of packaging technologies. For example, it can be applied to the insulating layer required for the redistribution layer (RDL) in fan-in and fan-out packaging, and can also be applied to the surface protection layer and back protection layer of silicon interposers in the through-silicon via technology.

[0009] In the composition of the present invention, the addition amount of the polyimide precursor is 1 wt% to 70 wt%. For example, it can be 1 wt% to 65 wt%, 2 wt% to 65 wt%, 2 wt% to 63 wt%, 3 wt% to 63 wt%, 3 wt% to 60 wt%, 5 wt% to 60 wt%, 5 wt% to 55 wt%, 10 wt% to 55 wt%, 10 wt% to 50 wt%, 15 wt% to 50 wt%, 15 wt% to 45 wt%, 20 wt% to 45 wt%, 20 wt% to 40 wt%, 25 wt% to 40 wt%, 25 wt% to 35 wt%, or 30 wt% to 35 wt%.

[0010] In the composition of the present invention, the polyimide precursor can be represented by the following formula (I):

[0011] (I);

[0012] Wherein, R is , and n is an integer. In addition, the molecular weight (Mw) of the polyimide precursor can be between 10,000 and 30,000, for example, it can be between 14,000 and 20,000. Furthermore, the polydispersity index (PDI, weight-average molecular weight / number-average molecular weight) of the polyimide precursor can be between 1.5 and 2.4.

[0013] In the composition of the present invention, the addition amount of the photoinitiator is 0.1 wt% to 10 wt%. For example, it can be 0.1 wt% to 9 wt%, 0.1 wt% to 8 wt%, 0.1 wt% to 7 wt%, 0.1 wt% to 6 wt%, 0.1 wt% to 5 wt%, 0.1 wt% to 4 wt%, 0.5 wt% to 4 wt%, 0.5 wt% to 3 wt%, or 1 wt% to 3 wt%.

[0014] In the composition of the present invention, there are no special restrictions on the type of photoinitiator. In one embodiment, the photoinitiator can be as shown in the following formula (II):

[0015] (II).

[0016] In the composition of the present invention, the addition amount of the ester monomer is 1 wt% to 10 wt%. For example, it can be 1 wt% to 9 wt%, 1 wt% to 8 wt%, 1 wt% to 7 wt%, 1 wt% to 6 wt%, 1 wt% to 5 wt%, 1 wt% to 4 wt%, or 2 wt% to 4 wt%.

[0017] In the composition of the present invention, there are no special restrictions on the type of ester monomer. In one embodiment, the ester monomer can be as shown in the following formula (III):

[0018] (III).

[0019] In the composition of the present invention, the solvent includes ethyl lactate and γ-valerolactone, and the weight ratio of ethyl lactate to γ-valerolactone (EL:GVL) is between 1:9 and 9:1. For example, it can be between 1:9 and 8:2, 1:9 and 7:3, 1:9 and 6:4, 1:9 and 5:5, 2:8 and 5:5, or 2:8 and 4:6. In one embodiment, the weight ratio of ethyl lactate to γ-valerolactone is about 3:7.

[0020] In the composition of the present invention, the addition amount of ethyl lactate, for example, can be 5 wt% to 40 wt%, 5 wt% to 35 wt%, 7 wt% to 35 wt%, 7 wt% to 30 wt%, 9 wt% to 30 wt%, 9 wt% to 27 wt%, 11 wt% to 27 wt%, 11 wt% to 23 wt%, 13 wt% to 23 wt%, 13 wt% to 21 wt%, 15 wt% to 21 wt%, or 15 wt% to 20 wt%.

[0021] In the composition of the present invention, the addition amount of γ-valerolactone, for example, can be 10 wt% to 70 wt%, 15 wt% to 70 wt%, 15 wt% to 65 wt%, 20 wt% to 65 wt%, 20 wt% to 63 wt%, 21 wt% to 63 wt%, 21 wt% to 60 wt%, 25 wt% to 60 wt%, 25 wt% to 55 wt%, 30 wt% to 55 wt%, 30 wt% to 50 wt%, 35 wt% to 50 wt%, 35 wt% to 45 wt%, or 40 wt% to 45 wt%.

[0022] The composition of the present invention may optionally further include a cyclization catalyst. Among them, the addition amount of the cyclization catalyst, for example, may be 0.1 wt% to 3 wt%, 0.1 wt% to 2.5 wt%, 0.5 wt% to 2.5 wt%, 0.5 wt% to 2 wt% or 0.5 wt% to 1.5 wt%.

[0023] In the composition of the present invention, the type of the cyclization catalyst is not particularly limited. In one embodiment, the cyclization catalyst is p-hydroxybenzaldehyde.

[0024] The composition of the present invention may optionally further include an adhesion promoter to enhance the effect of the composition. Among them, the addition amount of the adhesion promoter, for example, may be 0.1 wt% to 10 wt%, 0.1 wt% to 8 wt%, 0.1 wt% to 6 wt%, 0.1 wt% to 4 wt%, 0.1 wt% to 2 wt%, 0.5 wt% to 2 wt% or 0.5 wt% to 1.5 wt%.

[0025] In the composition of the present invention, the type of the adhesion promoter is not particularly limited. In one embodiment, the adhesion promoter can be as shown in the following formula (IV):

[0026] (IV).

[0027] The present invention also provides the use of the aforementioned polyimide photoresist composition in a low-temperature baking process, wherein the low temperature refers to below 250°C. In one embodiment, the temperature of the low-temperature baking can be between 150°C and 250°C, for example, it can be between 150°C and 200°C. In one embodiment, the temperature of the low-temperature baking can be about 170°C.

[0028] The present invention also provides a method for forming a patterned hard film using the aforementioned polyimide photoresist composition, including: coating the aforementioned polyimide photoresist composition on a substrate to form a film layer; performing exposure and development to pattern the film layer; and heating the patterned film layer to form a patterned polyimide hard film. Among them, the temperature of the heating treatment can be below 250°C, for example, it can be between 150°C and 250°C or between 150°C and 200°C.

[0029] The present invention also provides a semiconductor device, which includes: a polyimide hard film formed using the aforementioned polyimide photoresist composition. Detailed implementation mode

[0030] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific examples, and various details in this specification can also be modified and changed according to different viewpoints and applications without departing from the spirit of the present invention.

[0031] Unless otherwise specified in the text, the singular forms "a" and "the" used in the specification and the appended claims include one or a plurality of individuals.

[0032] Unless otherwise specified in the text, the term "or" used in the specification and the appended claims generally includes the meaning of "and / or".

[0033] In addition, in this text, the term "about" generally means within 20%, or 10%, or 5%, or 3%, or 2%, or 1%, or 0.5% of a given value or range. The given quantity is an approximate quantity, that is, the meaning of "about" can still be implied without specifically stating "about". In addition, the expression "the range is from the first value to the second value" or "the range is between the first value and the second value" means that the range includes the first value, the second value, and other values therebetween.

[0034] The present invention will be described more specifically through examples, but these examples are not used to limit the protection scope of the present invention. Unless otherwise specified, in the following preparation examples, examples and comparative examples, the temperature is in degrees Celsius, and the parts and percentages are by weight. The relationship between parts by weight and parts by volume is the same as the relationship between kilograms and liters.

[0035] Preparation of Polyimide Precursor

[0036] Add 151 g of ODPA (4,4'-Oxydiphthalic anhydride) to a 2 L separable round-bottom reaction flask, then add 427 g of NMP (1-Methyl-2-pyrrolidinone) and stir evenly. After adding 131 g of HEMA (2-Hydroxyethylmethacrylate) and 0.8 g of MEHQ (4-Methoxyphenol), add 98 g of pyridine, heat up to 60 °C, and stir and react for 18 hours.

[0037] Cool the reaction solution in an ice bath. After dissolving 165 g of DCC (N,N'-dicyclohexylcarbodiimide) in 237 g of NMP, add 80 g of ODA (4,4-oxydianiline). After adding ODA, react at room temperature for 2 hours.

[0038] Add 30 g of ethanol and react for 1 hour, then add 400 g of NMP and filter. Let the filtrate precipitate in ethanol to obtain a precipitate, filter to get the precipitate, then wash the precipitate with a large amount of deionized water, and dry the precipitate in a vacuum oven. The dried precipitate is the polyimide precursor.

[0039] Here, the obtained polyimide precursor is as shown in formula (I), with a molecular weight (Mw) of about 14,000 to 20,000 and a polydispersity index (PDI) of about 1.5 to 2.4.

[0040] Polyimide photoresist composition

[0041] Prepare the polyimide photoresist compositions of Examples 1 to 3 and Comparative Examples 1 to 4 according to the composition formula shown in Table 1 below. The preparation method is roughly as described below.

[0042] Prepare the polyimide photoresist compositions of Examples 1 to 3 and Comparative Examples 1 to 4 by mixing the polyimide precursor, photoinitiator, cyclization catalyst, adhesion promoter, ester monomer, and solvent according to the composition formula shown in Table 1 below. Among them, the polyimide precursor used is the polyimide precursor prepared above; the photoinitiator used is as shown in formula (II) (CAS No: 2097490-25-8); the ester monomer is as shown in formula (III) (CAS No: 109-17-1); the cyclization catalyst is p-hydroxybenzaldehyde (PHBAD) (CAS No: 123-08-0); the adhesion promoter used is as shown in formula (IV) (CAS No: 38280-61-4).

[0043] Cyclization rate test

[0044] First, prepare a 6-inch silicon wafer substrate. Next, spin coat the polyimide photoresist compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 4 onto the substrate evenly, respectively. Then, soft bake at 100 °C for 4 minutes, and then expose the polyimide photoresist composition coated on the surface of the substrate with an exposure machine. Then, develop by spraying cyclopentanone at 23 °C for 30 seconds. Then, perform a hard bake at 170 °C for 2 hours to form a hardened film of the polyimide photoresist composition. Finally, cool the substrate and the hardened film to room temperature to obtain the required samples, and the sample thickness is 8 μm.

[0045] Use an ATR-FTIR measurement device (manufactured by Bucker) to perform IR measurement on the above samples. Divide the peak intensity at 1380 cm -1 by the peak intensity at 1500 cm -1 The obtained value is set as the cyclization index. Divide the cyclization index of the hardened film in each example and comparative example by the cyclization index of the film obtained by hardening the corresponding polyimide photoresist composition at 350 °C for 2 hours, and calculate the obtained value as the cyclization rate. In Table 1, "◎" indicates a cyclization rate of 60% or more, and "○" indicates a cyclization rate of less than 60%.

[0046] Exposure latitude test

[0047] First, prepare a 6-inch silicon wafer substrate. Next, spin coat the polyimide photoresist compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 4 onto the substrate evenly, respectively. Then, soft bake at 100 °C for 4 minutes, and then expose the polyimide photoresist composition coated on the surface of the substrate with an Ultratech 1500 exposure machine (Boardband; NA = 0.24), and the exposure energy range is 100 - 3500 mJ. Then, develop by spraying cyclopentanone at 23 °C for 30 seconds to obtain a specified pattern. Finally, observe the patterns of each polyimide photoresist composition at different exposure energies after development with an optical microscope. Use the exposure energy range that can form a pattern with a resolution of L / S = 8 μm (±10%) in each example and comparative example as the exposure latitude and evaluate it. In Table 1, "◎" indicates an exposure latitude of 700 mJ or more; "○" indicates an exposure latitude of 400 to 700 mJ, and "X" indicates an exposure latitude of less than 400 mJ.

[0048] Table 1

[0049]

[0050] MEDG: Diethylene gylcol methyl ethyl ether

[0051] BMEM: Bis(2-methoxyethoxy)methane

[0052] NBP: N-butyl pyrrolidone

[0053] As shown in Table 1 above, compared with Comparative Examples 1 to 4 using ethyl lactate and other solvents (MEDG, BMEM, NMP, NBP), the polyimide photoresist compositions of Examples 1 to 3 using γ-valerolactone (GVL) and ethyl lactate (EL) as mixed solvents can simultaneously exhibit excellent cyclization rates of polyimide precursors and exposure latitudes. In particular, when the polyimide photoresist compositions of Examples 1 to 3 of the present invention are hard baked at a low temperature (170 °C), a good cyclization rate of the polyimide precursor can be obtained. On the other hand, in Comparative Example 3 using NMP and EL as solvents, both the cyclization rate of the polyimide precursor and the exposure latitude are worse than those of the polyimide photoresist compositions of Examples 1 to 3 of the present invention.

[0054] In summary, by using an environmentally friendly solvent combination other than NMP, a mixed solvent of γ-valerolactone (GVL) and ethyl lactate (EL), the present invention can promote the cyclization rate of polyimide precursors. In addition, by using the mixed solvent of the present invention, the photosensitive characteristics of the polyimide precursor can be effectively changed to have excellent exposure latitude. Furthermore, since these two solvents, γ-valerolactone and ethyl lactate, are both biomass-based environmentally friendly solvents, they can meet the characteristics of biomass, green chemistry, sustainability, biodegradability, and bioregeneration.

[0055] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polyimide photoresist composition, comprising: 1 wt% to 70 wt% of a polyimide precursor; 0.1 wt% to 10 wt% of a photoinitiator; 1 wt% to 10 wt% of an ester monomer; and the balance of a solvent, wherein the solvent comprises ethyl lactate and γ-valerolactone, and the weight ratio of ethyl lactate to γ-valerolactone is between 1:9 and 9:

1.

2. The polyimide photoresist composition according to claim 1, wherein The polyimide precursor is represented by the following formula (I): （I） wherein, R is , and n is an integer.

3. The polyimide photoresist composition according to claim 1, wherein, The molecular weight of the polyimide precursor is between 10,000 and 30,000.

4. The polyimide photoresist composition according to claim 1, wherein The photoinitiator is represented by the following formula (II): (II).

5. The polyimide photoresist composition according to claim 1, wherein, The ester monomer is represented by the following formula (III): (III).

6. The polyimide photoresist composition according to claim 1 further comprises: 0.1 wt% to 3 wt% of a cyclization catalyst.

7. The polyimide photoresist composition according to claim 6, wherein, The cyclization catalyst is p-hydroxybenzaldehyde.

8. The polyimide photoresist composition according to claim 1 further comprises: 0.1 wt% to 10 wt% of an adhesion promoter.

9. The polyimide photoresist composition according to claim 1, wherein, The polyimide photoresist composition does not include N-methylpyrrolidone.

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