DD295421A5 - POSITIVE WORKING PHOTO COPIER PAINT WITH CHEMICAL REINFORCEMENT - Google Patents

Abstract

The invention relates to a positive-working Photokopierlack with chemical Staaerkung that can be used for exposures in the wavelength range of 190 nm to 360 nm, is characterized in conjunction with a chemical amplification step by a high sensitivity and high resolution and excludes contamination by the base material. The photocopying varnish consists of one or more triarylsulfonium salts with fluorine-containing sulfonates as anions, a poly (tert-butoxycarbonyloxy-styrene) and a solvent or solvent mixture. Positive resist; chemical strengthening; Deep UV varnish; Laser lithography; triarylsulfonium; Poly (tert-butoxycarbonyl-oxy-styrene); Microelectronics}

Description

CF ₃ - (CXY) _n -CFZ-SO ₃ ⁰ with X = H, F, CF _3,

Y = F,

Z = H ₁ F, η = Obis 6 or for

CF ₃ - (CXY) _n -B- (CFZL-SO ₃ ⁰ with

B = O-CF ₂ ,

X = H, F, CF ₃ ,

Y = F, CF _3, H, Z = F, CF _3,

η = 1 to 8, m = 1.2

stands,

the poly (tert-butoxycarbonyl-oxy-styrene) and the solvent or solvent mixture and the photosensitive component is present in a concentration of 4Gew .-% to 25Gew .-% based on the total solids content.

2. A positive-type photocopying varnish according to claim 1, characterized in that the photocopying varnish as the photosensitive component is preferably diphenyl- (4-thiophenoxyphenyl) -sulfonium-1,1,1,2-tetrafluoroethanesulfonate, diphenyl- (4-thiophenoxy-phenyl) -heptafluoropropanesulfonate , Diphenyl- (4-thiophenoxy-phenyl) -sulfonium-1-pentafluoroethoxycarbonyl-1,2,2,2-tetrafluoroethanesulfonate or diphenyl- (4-thiophenoxyphenyl) -sulfonium-1,1,2,3,3,3-hexafluoro-1 contains - (pentafluoroethoxy) propane-2-sulfonate,

3. Positive-working photocopy lacquer according to claim 1, characterized in that are preferably used as solvent cyclohexanone, methyl glycol acetate, ethyl glycol acetate, butyl acetate, xylene or a mixture of at least two of these solvents.

4. A positive-type photocopying varnish according to claim 1, characterized in that the photosensitive component is preferably added in an amount of 20% by weight, based on the total solids content.

Field of application of the invention

The invention relates to a positive-working photocopying lacquer with chemical amplification, which can be used for exposures in the wavelength range of 190 nm to 360 nm and is suitable for the production of microelectronic components.

Characteristic of the known state of the art

Positive photoclake paints generally consist of a naphthoquinone diazide derivative as a photosensitive component and novolak as a polymeric binder (photoresists of the AZ type, H _.: J.Timpe, H.Baumann, Photopolymers, Deutscher Verlag für Grundstoffindustrie, Leipzig 1988). Upon exposure, photochemical conversion of the naphthoquinone diazide to the corresponding indenecarboxylic acid occurs, thereby dramatically increasing the solubility in the exposed areas. Aqueous alkaline solutions are used as developers (H. Böttcher, J.Bendig, H.-J.Timpe, G. Hopf, M. Fox, Technical Photochemistry, Deutscher Verlag für Grundstoffindustrie, Berlin 1990).

The resolving power of the AZ-type photoresists is limited by the wavelength of the exposure light, the shorter the spectral operating point the higher the potential resolving power (T.Iwayanagi, T. Ueno, S. Nonogaki, H. Ito, CG Willson, ACS-Symp Ser., 218, 1988, 109). Since the AZ-type photoresists in the deep UV range (190 nm to 360 nm) are only partially or not suitable, alternative photoresists have been developed (US Pat. No. 4,491,628, US Pat. No. 4,552,833, EP 0,292,821, DE 2,718. 254, EP 0.266.654)

 There are two types:

1. Two-component resists based on an onium salt as a photosensitive component and a Polyftert.-butoxycarbonyl-oxy-styrene) as a polymeric binder.

2. Three-component resists based on an onium salt as a photosensitive component, an acetal or ketal as a solubility inhibitor and a novolak or polyvinylphenol as a polymeric binder.

Common to these systems that are used as light-sensitive systems onium salts. During photolysis of these compounds, Brönstedt acids are produced (acidgeneration), which destroy the tert-BOC-substituted polymer or the solubility inhibitor in a subsequent chemical-amplification (CD) tempering step. The onium salts used are diaryliodonium or triarylsulfonium salts.

λ F

Favorable lithographic results are achieved when the onium salts are used with the anions (Α ^θ ) hexafluorophosphate (PF ₆ ⁸ ) or hexafluoroarsenate (AsFg ⁶ ). However, as these anions segregate as potential dopants and because of the consequent risk of contamination by the base material for use in device fabrication, appropriately modified onium salts, especially derivatives of trifluoromethanesulfonic acid, were tested. In the context of studies on photopolymerization shows that these onium trifluoromethanesulfonates far from reach the known Hexafluorophosphate and Hexafluoroarsenate in terms of sensitivity (H. -J.Timpe, H. Baumann, Photopolymers, German Verlag für Grundstoffindustrie, Leipzig 1988). The found gradation is

SbF ₆ ⁰ > AsFe®

PF _e

BF ₄ ® »CF ₃ SO ₃ ⁰ ~ FSO ₃ ^e.

Object of the invention

The aim of the invention is to develop a positive-working photocopying lacquer with chemical amplification, which operates in the wavelength range 190 nm to 360 nm, a high sensitivity and a high? Has dissolving power and because of its composition excludes contamination of potential dopants by the base material.

Explanation of the essence of the invention

The invention has for its object to develop a positive-working photocopying with chemical amplification, which operates in the wavelength range 190nm to 360nm, has high sensitivity and high resolution and excludes contamination of potential dopants.

According to the invention the object is achieved in that a positive-working photocopying with chemical amplification, consisting of one or more photosensitive components, a poly (tert-butoxycarbonyl-oxy-styrene) and a solvent or a solvent mixture is used, wherein the photocopy of a Sulfonium salt of the general formula I,

in which R ¹ , R ² and R ^{3 are} hydrogen, alkyl, unsubstituted or substituted aryl or heteroaryl and A ^{0 is}

CF ₃ - (CXY) _n -CFZ-SO ₃ ⁰ with

X = H ₁ F ₁ CF ₃ ,

Y = F,

Z = H, F,

η = 0 to 6

or for

CF ₃ - (CXY) _n -B- (CFZ) _n T-SO ₃ ⁰ with

B = O-CF ₂ , OC X = H, F. CF ₃ ,

F, CF ₃ , H,

F ₁ CF ₃ ,

1 to 8,

Y = Z = η =

m = 1.2

stands,

the poly (tert-butoxycarbonyl-oxy-styrene) and dom solvent or solvent mixture consists.

For the preparation of the photoresist usually in 10 to 40Gew .-% solids are dissolved in the solvent or in the solvent mixture. The proportion of the photosensitive component is 4 to 25% by weight, preferably 20% by weight. Suitable solvents are ketones, esters, ethers, aromatics, alcohols or mixtures thereof. Favorable properties include ethyl glycol acetate, methyl glycol acetate, butyl acetate, cyclohexanone and xylene.

The photoresist layers are produced by spin-on or similar conventional techniques. For lithographic application, layer thicknesses of 0.2 μm to 6 μm are suitable. The layer thickness can be adjusted in a targeted manner by varying the solids content and the resulting resist viscosity.

For the exposure of the resist layers mercury vapor lamps, high pressure mercury lamps and low pressure lamps or Excimeriaser (ArF: 193nm, KrF: 248nm, XeCI: 308nm) are suitable.

After Resistexposition the chemical amplification is carried out by heat treatment at 6O ⁰ C to 120 ⁰ C. The necessary annealing time is depending on the selected temperature 10s to 10 minutes.

For the development of the enhanced latent image aqueous alkaline developers are suitable, preferably sodium and potassium hydroxide, silicate and phosphate solutions or metal ion-free bases (tetramethylammonium hydroxide, choline).

The material according to the invention is characterized by a high sensitivity. It was surprising that the photocopying of the previously unknown triarylsulfonium sulfonates of general formula I with the meanings given for R ¹ , R ² , R ³ and Α ^eine have a higher sensitivity than those of the known hexafluorophosphates, arsenates and also the trifluoromethanesulfonates. Table 1 shows that after photolysis and thermolysis under comparable conditions, the resist layers with the triarylsulfonium sulfonates of the general formula I unpredictably require significantly shorter development times. The found grading contradicts the current state of knowledge, according to which only the Hexaf luoroantimonate, phosphates and arsenates are sufficiently reactive, while the sulfonates effect analogous to other anions such as the halides only a small effect.

Table 1

Necessary development time for selected resists under comparable conditions Polymer: Poly (tert-butoxycarbonyl-oxy-styrene)

diphenyl - (4-thiophenoxy-biphenyl) -sulfonium- BF ₄ ⁹ CF ₃ SO ₃ ⁰ PF ₆ ⁰ AsF ₆ ⁰ CH ₃ CFHSO ₃ ⁰ > 5min 150s Development time ¹¹ 110s 80s 35 s

1 developer E 270 (Photochemical Works Berlin).

The triarylsulfonium sulfonates of the general formula I used in the material according to the invention are novel, they are salts of cations known per se with new anions. Their synthesis is carried out by reacting the known triarylsulfonium chlorides (J.V. Crivello, J.L. Lee, Polym J. 17,1985.73) with the corresponding Alkalisulfonatlösungen.

-4- 205 421

The preparation of the Alkallsulfonattösungen, dio an anion of the general formula CFj- (CXY) _n -CFZ-SO ₃ ⁰ having the meaning indicated for X, Y, Z and η, is carried out by hydrolysis of bekannton (DC England, J. Amer. Chem. Soc., 82, 19660, 6181) 3-substituted 3,4,4-trifluoro, 2-oxa-thiethane-S, S-dioxides. Alkalleulfonates containing anionone of the general formula CF ₃ - (CXY) _n -B- (CFZJm-SO ₃ ⁰ with B = O-CO and the structure given for X, Y, Z, η and m are obtained by reacting 3 Substituted 3,4,4-trifluoro-1,2-oxa-thiethan-S, S-dloxiden with the corresponding alcohols and see eßendo Hydrolyso obtained (JMShreeve, Inorg Chem 27, 988, 13736.) Is the Hydrolye first after an electuctive fluorination of the carbonyl group with SF ₄ , one arrives at the compounds of the general formula CF ₃ - (CXY) _n -B- (CFZIm-SO ₃ ⁰ with B = O-CF ₂ and for X, Y, Z When the aqueous solutions of triarylsulfonium chloride and corresponding alkali metal sulfate are combined, the triarylsulfonium sulfonates of the formula I are precipitated, and the application of the anions according to the invention in the photoresist material avoids, during use, the base material to be processed comes into contact with potential Dotandon It has been shown by optical investigations that the content of moollionone or the content of potential dopants in the material according to the invention is significantly less than 1 ppm. For this reason contaminations should be excluded in the case of application.

Ausführungsbelsplele

Example KTab.1)

10 g of poly (tert-butoxycarbonyl-oxy-styrene) and 2, 50 g of diphenyl- (4-thiophenoxyphenyl) -sulfonium-1,1,1,2-tetrafluoroethanesulfonate are dissolved in 2.4 g of cyclohexanone.

The lacquer solution is finely filtered (0.2 μπι) and spun at 4000min * 'on silicon wafers. The layers were dried at 90 ⁰ C for 15 minutes. The resulting layer thickness was 0.6 μm.

The photoresist layer was exposed through a quartz mask with light oinor HBO 500 (contact method). Then took place 5min annealing at 90 ⁰ C. For the development of the structures, the developer E 270 was used (development time

Example 2

Preparation of the resist solution, exposure and processing was carried out analogously to Example 1, for the Resistexposition but a XeCI laser (308nm) was used.

Example 3

Preparation of the resist solution, exposure and processing was carried out analogously to Example 1, but for the exposure of the resist a KrF laser (248 nm) was used.

Example 4

Preparation of the resist solution, exposure and processing took place analogously to Example 1, but the actinic component was diphenyl (4-thiophenoxy-phenyl) sulfonium heptafluoropropansulfonat used.

Example 5

Preparation of the resist solution, exposure and processing took place analogously to Example 1, but the actinic component was diphenyl- (4-thiophenoxy-phenyl) -sulfonium-1,1,2,3,3,3-hexafluoro-1- (pentafluoroethoxy) -propane -2-sulfonate used.

Example 6

Preparation of the resist solution, exposure and processing took place analogously to Example 1, but the actinic component used was diphenyl- (4-thiophenoxyphenyl) sulfonium 1-pentafluoroethoxycarbonyl-1,2,2,2-tetrafluoroethanesulfonate.

Example 7

Preparation of the resist solution, exposure and processing took place analogously Buispis! 6 and 1, however, as the solvent, a mixture of ethyl glycol acetate, butyl acetate and p-xylene (80 wt%: 10 wt%: 10 wt%) was used.

Example 8 (Comparative Example, Tab. 1)

Preparation of the resist solution, exposure and processing took place analogously to Example 1, but the actinic component was diphenyl (4-thiophenoxy-phenyl) -sulfonium hexafluoroarsenat used.

Example 9 (Comparative Example, Tab. 1)

Preparation of the resist solution, exposure and processing were carried out analogously to Example 1, but the actinic component used was diphenyl (4-thiophenoxy-phenyl) -sulfop; um-hexafluorophosphate.

Example 10 (Comparative Example, Tab. 1)

Preparation of the resist solution, exposure and processing took place analogously to Example 1, but the actinic component was diphenyl (4-thiophenoxy-phenyl) sulfonium tetrafluoroborate.

Example 11 (Comparative Example, Tab. 1)

Preparation of the resist solution, exposure and processing took place analogously to Example 1, but the actinic component was diphenyl (4-thiophenoxy-phenyl) sulfonium trifluoromethanesulfonat used.

Claims (1)

1. A positive-working photocopying varnish with chemical reinforcement, consisting of one or more photosensitive components, a poly (tert-butoxycarbonyl-oxy-styrene) and a solvent or solvent mixture, characterized in that the photocopying varnish of a sulfonium salt of the general formula I, in which R ¹ , R ² and R ³ denote hydrogen, alkyl, unsubstituted or substituted aryl or heteroaryl and Α ^θ for