LITHOGRAPHIC MASK FOR IONS, ELECTRONS OR X-RAYS, AND PROCESS FOR ITS PRODUCTION

摘要

The mask has a semiconductor platelet (1) incorporating a region 2 - 3 mu m thick reduced in thickness to form a membrane (3) and a hole pattern (4) which defines the mask pattern and which is either etched through the membrane (3) or is produced in a layer (5) resting on the membrane (3). The membrane (3) is doped with a material which induces tensile stress in such a way that the doping has a minimum at the edge of the membrane (3) and a maximum at its centre, the doping difference between the edge and the centre being such that the membrane (3) is stress-free when irradiated with a specified radiation current. To produce the mask, the hole pattern is etched in an area of the semiconductor platelet (1) starting from one of its surfaces or is produced in a layer (5) resting on the surface, and the platelet is etched from the other surface until it is so thin that the hole pattern passes through it or until the rest of the membrane (3) is only 2 - 3 mu m thick, and the membrane is doped with material which induces tensile strength by means of ion implantation or ion diffusion which is proportional to the temperature distribution established during irradiation with electron or x-ray radiation of specified intensity.