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It is evident from Tables 3 and 4 that the resist compo- sitions of Examples have a high sensitivity and reduced LWR. The resist compositions of Comparative Examples have sensitivity and LWR values which are inferior to those of Examples. 

It is demonstrated that the resist composition comprising a polymer comprising acid labile group-substituted recur› ring units and preferably acid generator-bearing recurring units, to which a specific metal-acid complex is added, exhibits a high resolution, a high sensitivity, and a minimal LWR. The resist composition is best suited as the resist material for VLSis and patterning material for masks. 

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 

Japanese Patent Application Nos. 2015-023149 and 2015- 15 9402 are incorporated herein by reference. 

Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims. 

The invention claimed is: 

1. A resist composition comprising a polymer comprising recurring units of acid labile group-substituted (meth)acrylic acid, styrenecarboxylic acid or vinylnaphthalenecarboxylic 60 acid and/or recurring units having an acid labile group› substituted phenolic hydroxyl group, and an acid generator, or a copolymer comprising recurring units of acid labile group-substituted (meth)acrylic acid, styrenecarboxylic acid or vinylnaphthalenecarboxylic acid and/or recurring units 65 having an acid labile group-substituted phenolic hydroxyl group and recurring units having an acid generator, 

said resist composition further comprising a complex of a metal with an acid, the metal being selected from the group consisting of cerium, copper, zinc, iron, indium, yttrium, ytterbium, tin, thulium, scandium, nickel, neo› dymium, hafnium, zirconium, titanium, lanthanum, sil› ver, barium, holmium, terbium, lutetium, europium, dysprosium, gadolinium, rubidium, strontium, and cesium, and the acid being selected from the group consisting of a C$_{1 }$-C$_{4 }$ fluoroalkylsulfonic acid, CcC$_{12 }$ arylsulfonic acid having at least one fluorine atom which may be substituted with hydroxy group, C$_{1 }$-C$_{12 }$ alkoxy group or acyloxy group, or sulfonyl group, tetraphenylboric acid having at least one fluorine atom, C$_{1 }$-C$_{4 }$ fluoroalkylsulfonimidic acid, and C$_{1 }$-C$_{4 }$ fluoro› alkylsulfonemethide acid. 

2. The resist composition of claim 1 wherein the polymer comprising recurring units of acid labile group-substituted (meth)acrylic acid, styrenecarboxylic acid or vinylnaphtha› lenecarboxylic acid and/or recurring units having an acid labile group-substituted phenolic hydroxyl group has recur› ring units (al) and/or (a2), as represented by the general formula (1 ): 

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wherein R 1 and R 3 are each independently hydrogen or methyl, R 2 and R 4 each are an acid labile group, X$_{1 }$ is a single bond, a C$_{1 }$-C$_{12 }$ linking group having at least one of ester moiety, lactone ring, phenylene moiety and naphthylene moiety, a phenylene group, or a naphth- ylene group, X$_{2 }$ is a single bond or an ester or amide group, al and a2 are numbers in the range: 0sals0.9, 0sa2s0.9, and 0<al+a2<1. 

3. The resist composition of claim 1 which is a chemically amplified positive resist composition. 

4. The resist composition of claim 1, further comprising at least one component selected from among an organic solvent, a dissolution inhibitor, an acid generator, a basic compound, and a surfactant. 

5. A pattern forming process comprising the steps of coating the resist composition of claim 1 onto a substrate, baking, exposing the resulting resist film to high-energy radiation, and developing with a developer. 

6. The process of claim 5 wherein the high-energy radia› tion is EUV radiation having a wavelength of 3 to 15 nm. 

7. The process of claim 5 wherein the high-energy radia› tion is an electron beam at an accelerating voltage of 1 to 150 keV. 

8. A resist composition comprising a polymer comprising recurring units of acid labile group-substituted (meth)acrylic acid, styrenecarboxylic acid or vinylnaphthalenecarboxylic acid and/or recurring units having an acid labile group› substituted phenolic hydroxyl group, and an acid generator, or a copolymer comprising recurring units of acid labile group-substituted (meth)acrylic acid, styrenecarboxylic acid or vinylnaphthalenecarboxylic acid and/or recurring units 

