Negative photoresist used for semiconductor encapsulation process

Abstract

Provided is a negative photoresist used for a semiconductor encapsulation process, belonging to the technical field of semiconductor processing. A negative photoresist formulation includes 40-65 wt % of modified epoxy acrylate, 3-6 wt % of photosensitizer, 100-1000 ppm of leveling agent, and the remainder of solvent; the leveling agent is a solution of a 7:3 mass ratio of polydimethylsiloxane copolymer having a molecular weight of 3000-6000 and propylene glycol monomethyl ether acetate. If the negative photoresist is coated at a thickness of about 50 um, the coating uniformity can be controlled to below 5%, ensuring the quality of exposure such that the thickness of electroplated copper meets requirements.

Claims

1. A negative photoresist for a semiconductor encapsulation process, consisting of 40-65 wt % of a compound with a structure of: ##STR00003## 3-6 wt % of photosensitizer, 100-1000 ppm of a leveling agent, and a remainder of solvent; wherein m is an integer; wherein the compound has a molecular weight of 80,000-140,000 and a molecular weight distribution of 2.0- 4.0, wherein R is one of fluorine, hydrogen, hydroxyl, methoxyl, ethoxyl, methyl, ethyl, and propyl, and R.sub.1, R.sub.2, and R.sub.3 are respectively selected from one of hydrogen, methyl, and ethyl; and wherein the leveling agent is a solution of polydimethylsiloxane copolymer having a molecular weight of 3000-6000 and propylene glycol monomethyl ether acetate mixed with a mass ratio of 7:3.

2. The negative photoresist according to claim 1, wherein the photosensitizer is a mixture of (4-hydroxyphenyl)methylbenzyl sulfonium hexafluoroantimonate and 2-diazo-1-naphthol-5-sulfonyl chloride ester compound mixed with a mass ratio of 3:7.

3. The negative photoresist according to claim 1, wherein the solvent is one of a first solvent oil, a second solvent oil, and a third solvent oil, wherein the first solvent oil comprises a mixture of petroleum fractions, wherein the second solvent oil comprises trimethylbenzene and tetramethylbenzene, and also contains at least one of ethylbenzene and a mixture of ethylbenzene, and wherein the third solvent oil comprises a mixture comprising a light aromatic solvent.

4. The negative photoresist according to claim 1, wherein an amount of the leveling agent is 300-500 ppm.

Description

DETAILED DESCRIPTION

(1) A negative photoresist used for a semiconductor encapsulation process is provided. The formulation of the negative photoresist includes 40-65 wt % of modified epoxy acrylate, 3-6 wt % of photosensitizer, 100-1000 ppm of leveling agent, and the remainder of solvent. The leveling agent is a solution of polydimethylsiloxane copolymer having a molecular weight of 3000-6000 and propylene glycol monomethyl ether acetate mixed with a mass ratio of 7:3.

(2) The present disclosure will be further described in detail hereinafter in conjunction with specific examples.

EXAMPLES 1 TO 6

(3) Raw materials are mixed evenly according to the ratios shown in Table 1.

(4) The leveling agent is a solution of polydimethylsiloxane copolymer having a molecular weight of 3000-6000 and propylene glycol monomethyl ether acetate mixed with a mass ratio of 7:3. The leveling agent can affect the viscosity of the product and thus affect the coating uniformity.

(5) Specifically, the modified epoxy acrylate has the following structure, wherein m comprises an integer:

(6) ##STR00002##

(7) The modified epoxy acrylate has a molecular weight of 80,000-140,000 and a molecular weight distribution of 2.0-4.0. In the above structure, R is one of fluorine, hydrogen, hydroxyl, methoxyl, ethoxyl, methyl, ethyl and propyl, and R.sub.1, R.sub.2 and R.sub.3 are respectively selected from one of hydrogen, methyl and ethyl. The modified epoxy acrylate can affect the thickness of the coating film.

(8) The photosensitizer is a mixture of (4-hydroxyphenyl)methylbenzyl sulfonium hexafluoroantimonate and 2-diazo-1-naphthol-5-sulfonyl chloride ester compound mixed with a mass ratio of 3:7, The photosensitizer can affect the exposure performance of the product.

(9) The solvent is one of 200# SOLVENT OIL, 100# SOLVENT OIL and S-100 SOLVENT OIL, or a mixture of two or more thereof. The solvent can affect the coating uniformity. The 200# SOLVENT OIL comprising a mixture of petroleum fractions; the 100# SOLVENT OIL comprising trimethylbenzene and tetramethylbenzene, and at least one of ethylbenzene and a mixture of ethylbenzene; and the S-100 SOLVENT OIL comprising a mixture comprising a light aromatic solvent.

(10) The test manner is as following: under different rotating speeds, a 12-inch silicon wafer was baked at a temperature of 120° C. for 10 minutes and coated with photoresist with a thickness of 110 um, and the coating uniformity of the photoresist was tested by using the F50 film thickness meter from Filmetrics, Inc.

(11) TABLE-US-00001 TABLE 1 Example Example Example Example Example Example 1 2 3 4 5 6 Modified 40 65 50 55 46.5 53 epoxy acrylate/ wt % Photosensitizer/ 3 6 4 5 3.5 4 wt % Leveling agent/ 100 1000 300 400 500 800 ppm 200# 100# 200# S-100 100# S-100 SOLVENT SOLVENT SOLVENT SOLVENT SOLVENT SOLVENT Solvent/wt % OIL OIL OIL OIL OIL OIL 57 29 46 40 50 43

(12) The test manner is as follows.

(13) Film thickness uniformity test: the tested photoresist was coated by using a spin coater, and baked at 110° C. for 5 minutes after coating, and the coating thickness and uniformity were tested by using a film thickness meter.

(14) The results are shown in Table 2.

(15) TABLE-US-00002 TABLE 2 Film thickness/um Center At ½ At ¼ At ⅛ Edges Average u % Example 1 55.2 57.9 59.3 62.8 66.1 60.26 9.0 Example 2 52.3 53.5 54.8 55.7 57.7 54.8 4.9 Example 3 50.3 51.5 51.8 53.2 54.7 52.3 4.2 Example 4 49.4 49.9 50.4 51.2 51.9 50.56 2.5 Example 5 50.6 51.1 51.8 52.5 53.7 51.9 2.9 Example 6 50.5 50.9 51.7 53.5 55.8 52.5 5.0

(16) As can be known in Table 2, when the negative photoresist is coated at a thickness of about 50 um, the coating uniformity can be controlled to below 5%, ensuring the quality of exposure such that the thickness of electroplated copper meets requirements.

(17) The above are only some embodiments of the present disclosure. For those skilled in the art, a number of improvements and modifications can be made without departing from the principle of the present disclosure, and these improvements and modifications are within the scope of the present disclosure.