1. A semiconductor integrated circuit including an impedance element comprising: (a) a semiconductor body having a major planar horizontal surface; (b) an insulating layer located on the major surface; (c) a polycrystalline silicon plug substantially filling an aperture having substantially vertical sidewalls in the insulating layer and thereby directly contacting the major surface of the body at the bottom of the aperture, the plug having a vertical height greater than one-half the maximum width of the aperture, the grain boundaries in the plug running substantially solely horizontally in a region thereof situated at a distance of more than one-half such width from the major surface of the body, said region including a complete horizontal cross section of the aperture.