摘要 |
A method of forming buried regions in a printed circuit substrate in which; a first layer of doped silicon oxide is deposited on the substrate, a pattern of apertures is produced in this layer and a second layer of differently doped silicon oxide is deposited to fill in apertures. The first layer silicon dioxide acts as a mask to the doping material so that when the two layers are subjected to a common diffusion step both doping materials are driven into the substrate, with the second layer doping material restricted to the regions of the apertures. |