The method supplies self-aligned metal to silicon contacts and sub-micron contact-to-contact and metal-to-metal spacing in the Integrated Injection Logic (I 2 L) or Merged Transistor Logic (MTL) technology. The insulation between the contacts and the metal is a pattern of dielectric material (24, 26, 30) having a thickness dimension in the order of a micron or less.
The method involves providing a silicon body (10, 12) and then forming a first insulating layer (16) on the silicon body. This layer is removed in areas designated to contain integrated injection logic devices. A layer (20) of highly doped polycrystalline silicon is formed thereover. The conductivity of the polycrystalline silicon is opposite to that of the silicon body. Openings are made in the polycrystalline I silicon layer (20) by reactive ion etching which results in the structure having substantially horizontal and vertical surfaces. The openings are formed in areas designated to be the base of the lateral injector transistor of the integrated circuit. A second insulating layer (24, 26, 30) is then formed on both the substantially horizontal surfaces and substantially vertical surfaces. Reactive ion etching of this second insulating layer (24, 26, 30) substantially removes the horizontal layers and provides a narrow dimensioned dielectric pattern of regions on the silicon body. The base of the lateral injector transistor is formed through the openings of the polycrystalline silicon layer (20). The structure is annealed to fully form the base of the transistor and to drive into the silicon body the opposite type impurities from the polycrystalline silicon layer (20) to thereby form the base regions for the vertical transistors of the integrated injection logic circuit. Additional openings and narrow dimensioned dielectric patterns are made in the polycrystalline silicon layer where the collector of the vertical transistor is to be formed. Finally the structure is contacted and planarized.