layer then the resist layer 20 and the protective layer 24 are patterned and a recess having a first base surface is produced in the substrate 11 by means of an etch fig1 b after the resist layer 20 and the protective layer 24 have been removed the half tone layer 15 is deposited followed by the resist layer 22 and the latter is patterned by means of conventional photolithographic processes fig1 c and 11 d a subsequent etch produces the openings 13 and 14 in the half tone layer 15 the opening 14 being formed in the recess which has previously been structured in the substrate the dimensions and position of the opening 14 relative to the recess are selected in such a way that the side walls 33 of the recess and a part of the base surface 31 of the recess are covered by the half tone layer 15 then the resist layer 22 is removed and the finished mask is obtained a further variant of the method according to the invention is illustrated in fig1 the first two steps fig1 a and 12 b of the method correspond to the steps which have already been described in connection with fig1 a and 11 b then as illustrated in fig1 c first of all a half tone layer then a protective layer 24 and then a resist layer 22 are deposited on the prepatterned quartz substrate 11 the half.