FORMATION OF CONTACT WINDOW

PURPOSE:To correct the over-exposure of photo-resist film by exposure light beam that scatters on a polycrystalline Si layer by making the width of the pattern section corresponding to the window pierced in the insulation window on a polycrystalline Si layer in the pattern formed on a light exposure mask for opening contact window different from a specified value. CONSTITUTION:After forming a specified active area such as source, drain on an Si substrate 1, a gate oxidation film 2 is covered on its surface, and on this film a polycrystalline Si layer 3 is grown that is to become gate electrodes later on. Next, on the surface oxidation film 7 that has grown by this forming an interlayer insulation film 8 is attached by CVD method, and on this film 8 a photo-resist film 9 is provided. Thereafter, the film 9 is exposed to light by using a light exposure mask 10. At this time, the width 12 of an opening pattern 11 that is provided at the mask 10 is made a little larger than the width 1 of the area to be exposed to light. With this arrangement, light exposure area of a desired width can be obtained even if there is surplus light that is reflected from the polycrystalline Si layer 3.