JPH0157778B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel photosensitive material. More specifically, the present invention relates to a photosensitive material used as a photoresist that utilizes the photoreactivity of an aryl cyclic sulfonium zwitterion. Sensitivity and resolution can be cited as the required performances of photoresists, which play an important role in the production of electronic components such as ICs and LSIs. However, conventionally widely used negative photoresists, such as photoresists made of cyclized rubber, have the disadvantage of poor resolution because the image portion remaining on the substrate swells during development. On the other hand, the existence of aryl cyclic sulfonium zwitterions has been known so far, and these water-soluble ions can be used to form water-insoluble polymers through thermal polymerization. Applications to coating materials have been considered.
(For example, Japanese Patent Application Laid-Open No. 48-28531, US Patent No. 3,544,489) As a result of intensive research on various aryl cyclic sulfonium zwitterions, the present inventor found that they are easily polymerized by light and have excellent sensitivity and resolution as photoresists. The present invention was achieved based on the discovery that That is, the present invention provides a photosensitive material comprising an aryl cyclic sulfonium zwitterion having a structure represented by the following general formula (M). In the formula, φ is

[Formula]; R is Cl, Br, or a C ₁ to C ₄ alkyl group; and a indicates the number of φ substituted in R and is 0, 1 or 2; A is -
C ₄ H _8-b R ¹ _b − or −C ₅ H _10-b R ¹ _b − and R ¹ is C ₁
~ _C4 alkyl group or phenyl group; b is 0, 1
or 2; (-) _o is a bond indicating that it may be bonded to another molecule, and n is 0, 1, or 2 indicating the number of bonds. Next, the present invention will be explained in detail. An example of the case where n=2 in the above general formula (M) is an aryl cyclic sulfonium zwitterion having a structure represented by the following general formula (M1). In the formula, (M) represents the general formula (M), and at least one of them exists in the general formula (M1). (N) is

[Formula] is shown, and φ, R and a are the same as in general formula (M). ^R2 and ^R3 are H, Cl, Br, OH or a _C1 - _C4 alkoxy group, and ^R2 and ^R3 may be the same or different. Z and m are in any of the following cases (1) to (4). (1) Z is -O-, -S- or -O(C _l H _2l )O
-: m is 0-1, and l is 1-6. (2) Z is −CR ² ₄ −; m is 0 to 1, and R ⁴ is
It is a _C1 - ^C4 alkyl group. (3) Z is

[Formula] m is 0-1, and k is 0-6. (4) Z is -CH ₂ -: m is 0 to 30. Specifically, for example, in general formula (M1),
φ：

[Formula] a: 0, A: -C ₄ H _8-b R ¹ _b -, b is 0, Z: -O(C _l H _2l ) O-, l
is 3, m is 1, R ² and R ³ :H, the formula () in Example 2 below is obtained, and φ:

[Formula] a: 0, A: -C ₄ H _8-b R ¹ _b -, b is 0,
When Z: -O-, R ² and R ³ :H, the formula () in Example 2 below is obtained. An example of the case where n=1 in the above general formula (M) is an aryl cyclic sulfonium zwitterion having a structure represented by the following general formula (M2) or (M3). In the formula, ^R5 is H or a _C1 - _C4 alkyl group. Specifically, for example, in general formula (M2),
When A: -C ₄ H ₈ -, a: O, R ⁵ : H, the formula () in Example 2 below becomes the formula (), and in the general formula (M3), A: -C ₄ H ₈ -, a: O , R ⁵ : When CH ₃ ,
This is the formula (XI) in Example 2 below. These aryl cyclic sulfonium zwitterions are soluble in water, lower alcohols, etc., and by applying these solutions of aryl cyclic sulfonium zwitterions to a substrate by brushing, spin coating, spray coating, etc. A coating film can be easily formed. In particular, Z and m shown in the above general formula (M1)
The aryl cyclic sulfonium zwitterion when (f) forms a homogeneous and good coating film, in which case m=0
The coating film with a value of ~20 is the best. Furthermore, the aryl cyclic sulfonium zwitterion in which R is C1 in the above general formula (M) is stable against heat and does not polymerize even when heated in the dark at 80° C. for 30 minutes. The position of the sulfonium group in the above general formula (M) is mainly synthesized as ortho or para to the phenoxy group, and both have photosensitivity, but para has higher sensitivity. As the light to be irradiated to polymerize these aryl cyclic sulfonium zwitterions, ultraviolet rays with a short wavelength of 400 nm or less are effective. In the above general formula (M), φ is

[Formula] in which A is unsubstituted or substituted with an alkyl group has a photosensitive wavelength range from about 250 nm to about 300 nm, and is a photosensitive material sensitive to so-called deep ultraviolet rays. On the other hand, in the above general formula (M), when A is substituted with phenyl, the photosensitive region shifts to the longer wavelength side by 10 to 70 nm, and the sensitivity becomes a photosensitive material with even higher sensitivity. These aryl cyclic sulfonium zwitterions polymerize immediately upon irradiation with light and become insoluble in water. When used as a photoresist, development after light irradiation can usually be carried out using water or lower alcohol as a developer, and a negative image can be obtained. Furthermore, if an appropriate organic solvent is used as a developer, it is possible to elute only the light-irradiated areas and obtain a positive image. After development, it is also possible to heat the film at 60 to 200° C. to thermally react the residual film portion, which is an image, to further increase the resistance to subsequent etching steps. The aryl cyclic sulfonium zwitterion in the present invention can be used alone as a photosensitive material, but it can also be used in combination with a sensitizer, a stabilizer, an antihalation agent, etc. It can also be used in combination with other polymers, such as novolak resin, polyvinylphenol, butadiene-acrylic acid copolymer, vinyl acetate polymer partial hydrolyzate, etc., if necessary. The photosensitive material of the present invention does not cause the image to swell during development, and is industrially useful as a high-sensitivity, high-resolution photoresist. The present invention will be explained in more detail below with reference to Examples. Note that, hereinafter, the aryl cyclic sulfonium zwitterion will be simply referred to as a zwitterion. Example 1 51 g of O-cresol was dissolved in 150 ml of methanol, and HCl gas was passed through and absorbed at -5°C. Thereafter, 1 g of aluminum chloride was added, and 48 g of tetrahydrothiophene 1-oxide was slowly added dropwise at 0 to 5°C. After the reaction, methanol was removed under reduced pressure and acetone was added to precipitate a solid (zwitterion HCl salt). Dissolve this in methanol 1 again, add a strong base type anion exchange resin (Amberlite IRA-400) treated to OH type and stir until the pH of the liquid becomes 11.5. After filtering off the ion exchange resin, methanol was removed under reduced pressure and acetone was added. When the mixture was heated, the following zwitterion () was precipitated as a white solid. Concentration of zwitterion () dissolved in methanol
When applied at 10% by weight and brushed onto a polyester film, a good coating film was obtained. A mask pattern was placed on top of this, and the pattern was irradiated with light from a 250W ultra-high pressure mercury lamp for 2 minutes, then immersed in water for 30 seconds and developed, leaving the irradiated areas and dissolving the unirradiated areas to form an image. Separately, a sheet coated with zwitterion () was attached to the bottom of a shear dish floating in ice water, and when light was irradiated for 2 minutes in the same manner as above, an image was also formed by development. In this case, the temperature of the top surface of the zwitterion coating during light irradiation is 10
It was below ℃. This revealed that zwitterions can be polymerized by photoreaction even at low temperatures. Next, this zwitterion () was evaluated as a far-UV resist. Zwitterion (20)
Weight% ethanol solution onto silicon wafer
Spin coating was performed at 1000 rpm to form a coating film with a thickness of 1 μm. Next, this sample was irradiated with deep ultraviolet light (250 to 350 nm) through a mask pattern for evaluation. The exposure machine used was PLA-521F manufactured by Canon Inc., and the light source used was a far ultraviolet ray 500WXe-Hg short arc lamp UXM-500MD manufactured by Ushio Electric Co., Ltd. As a result, a resolution of 3 μm and a sensitivity of 770 joul/m ² were obtained. Example 2 In place of O-cresol in Example 1, phenol, 2,5-dimethylphenol, p-cresol, biscatechol trimethylene ether, 4,
Example 1 was carried out using 4'-dihydroxydiphenyl ether, bisphenol A oxalic acid (4,4'-hydroxyphenyl) ester, novolac resin, polyvinylphenol, and poly(methacrylic acid-2-hydroxyphenyl ester). The following zwitterions () to (XI) were synthesized in the same manner.

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] Note that in () to (XI), not all phenol nuclei have sulfonium groups attached. Furthermore, the averages of j in () to (XI) were 4.5, 40, and 300, respectively. All of the zwitterions () to (XI) were soluble in aqueous alkaline solutions and methanol. When these methanol solutions were applied on a polyester film, a coating film could be formed, and in particular, uniform and smooth coating films were obtained from () to (XI). When a light irradiation test using an ultra-high pressure mercury lamp was carried out in the same manner as in Example 1, all of them showed photosensitivity. Optimum exposure time for zwitterion of Example 1 ()
The results are shown in Table 1. Of these, Zwitterion (), which has a good coating film, was evaluated as a far-UV resist in the same manner as in Example 1, and it was found that the resolution was 1 μm, the sensitivity was 500 joul/
The value of m ² was obtained. Example 3 20 g of 1,5-dibromopentane and 8.4 g of 4-(methylthio)phenol were added to 30 ml of chlorobenzene and reacted at 120° C. for 3 hours. The resulting solid was recrystallized from methanol/ethyl ether to obtain the zwitterion HCl salt. After treating the HCl salt of this zwitterion with the anion exchange resin of Example 1 in methanol, the solvent was removed and acetone was added to obtain the following zwitterion (XII) as a white solid. As in Example 1, a light irradiation test using an ultra-high pressure mercury lamp was carried out, and as a result, the zwitterion (XII) showed photosensitivity. Table 1 shows the optimum exposure time. Example 4 49 g of benzyl mercaptan and 70 g of tetramethylethylenediamine were dissolved in 800 ml of a mixed solution of tetrahydrofuran/n-pentane, and 54 g of n-butyllithium was added at -5°C, followed by stirring for 2 hours. Thereafter, the mixture was cooled to -78°C, and 90 g of 1,3-dibromopentane was added thereto, reacted for 3 hours, and then returned to room temperature. After removing the solvent, washing with water, drying, and distilling, 2-phenylthiophane was obtained as a fraction of 95-98℃/1mmHg.

I got [formula]. 11 g of 35% hydrogen peroxide solution was slowly added dropwise to 18 g of 2-phenylthiophane while stirring vigorously at 5° C., and the mixture was allowed to react for 3 hours. After removing water under reduced pressure, distill it under reduced pressure to obtain a fraction of 150-155℃/2mmHg.
Phenylthiophane-1-oxide

I got [formula]. Next, tetrahydrothiophene-1 of Example 1
The following zwitterion () was obtained in the same manner as in Example 1 except that the above 2-phenylthiophane-1-oxide was used instead of the -oxide. As in Example 1, a light irradiation test using an ultra-high pressure mercury lamp was carried out, and as a result, the zwitterion () exhibited high photosensitivity. Table 1 shows the optimum exposure time. Example 5 30 g of HCl salt of zwitterion () obtained in Example 2
was dissolved in 200 ml of glacial acetic acid, and chlorine gas was passed through the solution while cooling with ice to perform a reaction with chlorine. After the heat generation has disappeared, chlorine gas is passed through for another 30 minutes, the precipitate formed is collected, and the zwitter ions are removed.
HCl salt was obtained. This was treated with the ion exchange resin to obtain the following zwitterion () as a white solid. Zwitterion () was applied to a polyester film, left at 80°C for 30 minutes, and then immersed in water, where it completely dissolved, indicating that no thermal polymerization occurred. Further, the coated sheet heated at 80° C. for 30 minutes was subjected to a light irradiation test using an ultra-high pressure mercury lamp in the same manner as in Example 1, and as a result, it was found to have photosensitivity. Table 1 shows the optimum exposure time.

【table】

Claims (1)

[Scope of Claims] 1. A photosensitive material comprising an aryl cyclic sulfonium zwitterion having a structure represented by the following general formula (M). In the formula, φ is [Formula] R is Cl, Br, or a C ₁ to C ₄ alkyl group; and a represents the number of R substituted with φ, and is 0, 1 or 2; A is -
C ₄ H _8-b R ¹ _b − or −C ₅ H _10-b R ¹ _b −, and R ¹ is
C ₁ - C ₄ alkyl group or phenyl group; b is 0,
1 or 2; (-) _o is a bond indicating that it may be bonded to another molecule, and n is 0, 1, or 2, indicating the number of bonds.