METHOD FOR PRODUCING PHOTOMASK BLANKS Russian patent published in 2005 - IPC

FIELD: electronic industry.

SUBSTANCE: proposed method for producing photomask blanks includes mechanical treatment of glass wafers using cerium dioxide based polishing powders and nonwoven material based polishing cloth, their treatment in aqueous solutions of organic acids, treatment in neutral water medium followed by dehydration, drying, and check-up. Mechanical treatment is conducted at proportion of polishing power effective diameter, diameter of synthetic fibers of nonwoven cloth and its volume density being 1 : 2-4 : 0.2-0.3 with cerium dioxide content in polishing powder being minimum 80 mass percent. Cerium dioxide to ferric oxide ratio and sum of neodymium and praseodymium oxides can be chosen between 1 : 0.05 and 0.08 : 0.1-0.2.

EFFECT: reduced cost of photomask blank due to reducing number of mechanical treatment stages and optimal choice of proportions in parameters of materials used for mechanical treatment.

2 cl, 1 tbl