Photoresist with positive-resist behaviour, method for photochemical structuring thereof, method for the production of silanes and of silicic acid (hetero)poly(co)condensates with positive-resist behaviour and also silicic acid (hetero)poly(co)condensates

Abstract

The present invention relates to a special heteropolymer, namely a silicic acid (hetero)poly(co)condensate with positive-resist behavior which is distinguished by polycondensation or copolycondensation of specially modified silanes. The invention relates likewise to monomeric silanes from which the corresponding heteropolymers, i.e. the silicic acid (hetero)poly(co)condensates, can be produced. The silicic acid (hetero)poly(co)condensates according to the invention can be used for a photoresist which has positive-resist behavior. In addition, the invention relates to corresponding methods both for the production of the silanes, the silicic acid (hetero)poly(co)condensates or a method for photochemical structuring of the photoresist according to the invention which is based on the silicic acid (hetero)poly(co)condensates.

Claims

1. A photoresist with positive-resist behaviour, consisting of a) a silicic acid (hetero)poly(co)condensate with positive-resist behaviour, which is producible from a silane of general formula I
[P(Y.sup.1).sub.cX(Y.sup.2).sub.c].sub.aSi(R.sup.1).sub.b(R.sup.2).sub.4-a-bFormula I P being a group which can be made photolabile and being selected from the group consisting of radicals of general formula IV, ##STR00011## R.sup.3 being selected from the group consisting of linear or branched alkyl radicals with 1 to 18 carbon atoms, trialkylsilyl groups, and ester groups, X representing the grouping: ##STR00012## Z being selected from the group consisting of S, O, NR.sup.4, and C(R.sup.4).sub.2, R.sup.4 being the same or different with each occurrence and being selected from the group consisting of hydrogen and linear or branched alkyl radicals with 1 to 18 carbon atoms, cycloaliphatic groups with 6 to 24 carbon atoms or aromatic groups with 6 to 24 carbon atoms and n being 1, Y.sup.1 and Y.sup.2 being the same or different with each occurrence and being selected from the group consisting of saturated or unsaturated alkylene groups with 1 to 18 carbon atoms, cycloaliphatic groups with 6 to 24 carbon atoms and aromatic groups with 6 to 24 carbon atoms, R.sup.1 being selected from the group consisting of linear or branched alkyl radicals with 1 to 18 carbon atoms, cycloaliphatic groups with 6 to 24 carbon atoms and aromatic groups with 6 to 24 carbon atoms, R.sup.2 representing an OR .sup.3 group, R.sup.3 being selected from the group consisting of linear or branched alkyl radicals with 1 to 18 carbon atoms, cycloaliphatic groups with 6 to 24 carbon atoms and aromatic groups with 6 to 24 carbon atoms, a being 1, 2 or 3, b being 0, 1 or 2, with the condition that a and b are chosen such that there applies: 4-a-b1, c being 0 for the radical Y.sup.1 and 1 for the radical Y.sup.2, in which the silane of general formula I under conditions in which hydrolysis takes place, of the radical R.sup.2, is polycondensed or copolycondensed with at least one further hydrolysable silane compound, b) at least one solvent, and c) a photoactivatable compound which during photoactivation degrades the group P which can be made photolabile.

2. The photoresist according to claim 1, wherein the at least one solvent is selected from the group consisting of propylene glycol monomethylether-1,2-acetate (PGMEA, CAS-no.: 108-65-6), methyl isobutyl ketone, n-propyl acetate, butyl acetate, butyl lactate, ethanol or mixtures thereof.

3. The photoresist according to claim 1, wherein the photoactivatable compound is a photoacid generator which is selected from the group consisting of onium salt photoacid generators, halogen-containing photoacid generators, and sulphonic acid- and sulphonate-containing photoacid generators.

4. A method for photochemical structuring of a photoresist according to claim 1, wherein a substrate is coated with the photoresist by centrifugal coating and the obtained layer made of the photoresist is exposed in regions with radiation, wherein a) the photoactivatable compound being activated and consequently the group P which can be made photolabile being degraded, or b) the photolabile group P being degraded.

5. The method according to claim 4, wherein the photoresist, after exposure, is subjected to a development step, the coating being treated with an aqueous-alkaline solution.

6. The method according to claim 4, wherein the coating is treated thermally after deposition and/or after exposure.

7. The method according to claim 6, wherein the coating is treated thermally at temperatures of 60 to 200 C. over a period of 1 s to 10 min, after deposition and/or after exposure.

8. The photoresist according to claim 1, wherein R.sup.3 is selected from the group consisting of t-butyl-, 1-ethylnorbornyl-, 1-methylcyclohexyl-,1-ethylcyclopentyl-, 2(2-ethyl)adamantyl-, t-amyl, trimethylsilyl-, triethylsilyl-dimethyl-tert-butylsilyl, and t-butoxycarbonyloxy (t-BOC), and 3-oxocyclohexyl group.

9. The photoresist according to claim 8, wherein the photoactivatable compound is a photoacid generator which is selected from the group consisting of onium salt photoacid generators, halogen-containing photoacid generators, and sulphonic acid- or sulphonate-containing photoacid generators.

10. A method for photochemical structuring of a photoresist according to claim 8, wherein a substrate is coated with the photoresist and the obtained layer made of the photoresist is exposed in regions with radiation, a) the photoactivatable compound being activated and consequently the group P which can be made photolabile being degraded, or b) the photolabile group P being degraded.

11. The method according to claim 10, wherein the photoresist, after exposure, is subjected to a development step, the coating being treated with an aqueous-alkaline solution.

Description

EMBODIMENTS

Example 1

Synthesis of the Monomer

(1) Monomer production of an ORMOCER with photolabile substituents

(2) In a flask rinsed with argon, 55.45 mmol (7.886 g) of t-butyl methacrylate is introduced and diluted with 16.99 g of n-propyl acetate. Subsequently, 55.45 mmol (13.222 g) of 3-mercaptopropyl triethoxysilane is added thereto. A newly produced 88% KOH solution (3.13 g, 0.55 mmol KOH) is added slowly to the mixture in drops.

(3) Conversion of the silane according to the invention is thereby effected by thiol-ene reaction of the thiol group to the unsaturated grouping of the acrylate group.

Example 2

Production of the Polycondensate

(4) After conclusion of the reaction in example 1, there is added to a fifth of the batch, 101 l of a 1.1 M NH.sub.4F solution and also 16.6 mmol (0.299 g) of water and the reaction mixture is agitated for 16 h at 25 C. Subsequently, 22.8 ml of PGMEA is added to the reaction mixture and the synthesis product is obtained by distillative removal of the volatile components released during the hydrolysis and condensation. The solvent PGMEA is thereby left in the reaction mixture so that already a finished photoresist is obtainable.

Example 3

Structuring and Development of the Photoresist

(5) The synthesis product which already comprises the solvent PGMEA is applied on a substrate, after addition of a photoacid generator (PAG, Cyracure 6975), by means of centrifugal coating. With the dilution, the thickness of the photoresist can be adjusted, for example to 500-1,000 nm. After the centrifugal deposition, a pre-bake is implemented for 1 min at 120 C. Subsequently, the layer is exposed in a mask exposer (Hg vapour lamp, I-line) for 30 s. In the next step, a post-exposure bake is effected for a further 1 min at 120 C. The exposed places can be developed subsequently with an aqueous-alkaline solution (TMAH). The non-exposed product can likewise be removed (stripping), in the subsequent process for example by means of methylisobutyl ketone.

Example 4

Etching Stability

(6) The layer obtained after the photostructuring and development was subsequently subjected to an argon plasma (power: 300 W, argon pressure: 1.0*10.3 mbar). The plot of the time-dependent removal shows that the ORMOCER underlying this invention behaves with positive-tone behaviour, relative to a back-sputtering process (argon plasma), in at least as stable a manner as conventionally crosslinked ORMOCERs (FIG. 1).

(7) ORMOCERs already offer, as separate material class, a wide portfolio of application possibilities and adjustable properties which is determined in part by the photostructurability of the ORMOCERs. The method of the negative-resist which is used exclusively at present thereby reaches its limits time after time because of the organic solvents required in the development step. Frequently, photoresists, the solubility of which is provided in aqueous systems, are demanded on the part of the user. The present invention offers a solution to this problem since the exposed regions of the system developed here are soluble in aqueous solutions (e.g. TMAH). In combination with the already very wide application field of the ORMOCERs, new application possibilities arise therefore for the material class described in the present invention.

(8) Furthermore, the resolution in photoresists which are based upon positive-tone behaviour is generally better than in the corresponding negative-tone photoresists. Thus, it can be expected that, in comparison to conventional ORMOCERs, the resolution is improved and can be increased even further in addition by means of the contact exposure which is possible in this case.