Abstract: A method of fabricating a semiconductor device comprising the steps of disposing a layer of dopant material over exposed portions of a surface of a semiconductor body and over portions of a masking layer adjacent the exposed portions, the dopant material having a diffusion coefficient through the masking layer at least about as large as its diffusion coefficient into the body. The dopant material is selectively etched to remove portions overlying the masking layer and thereafter remaining portions of the masking layer are etched to remove any dopant material which might still remain thereover.

Abstract: A diffusion apparatus, particularly useful for diffusing aluminum into semiconductor wafers, comprises a quartz evaporation tube in combination with a restrictor plate which is inserted in an open end thereof. The restrictor plate preferably has substantially the same shape as, but a slightly smaller cross-section than, the evaporation tube. In practice, the relatively small gap between the restrictor plate and the evaporation tube results in a substantially negligible leak in the diffusion apparatus. As a result the apparatus effectively operates as if it were a sealed ampule while in fact it is open, i.e. not sealed.

Abstract: Uniform aluminum diffusion into monocrystalline silicon is obtained by forming a polycrystalline silicon underlayer on the surface of a monocrystalline silicon body, depositing a layer of aluminum on the polycrystalline silicon underlayer by evaporation at a temperature of less than about 250.degree. C., depositing a silicon overlayer over said aluminum layer at a temperature less than about 250.degree. C. and raising the temperature of said structure to between 900.degree. C. and 1300.degree. C. to cause the aluminum to diffuse into said monocrystalline silicon.

Abstract: A method of fabricating a semiconductor device having a one type conductivity portion substantially surrounded by a second type conductivity portion is disclosed. The method involves selectively diffusing different impurities having the same conductivity inducing effect. The disclosed method is particularly adaptable to forming a plurality of devices in a relatively thick semiconductor wafer.

Abstract: A method of fabricating a semiconductor device comprises steps for forming recesses which can be used in the subsequent visual alignment of photomasks. The novel recess forming steps are so linked with a conventional processing step that the total number of steps required for the formation of the recesses is reduced. The present method is particularly adaptable to the fabrication of unisurface silicon controlled rectifiers wherein a doped isolation-type grid is formed to define each device.

Abstract: A silicon substrate is coated with a mask comprised of the combination of a silicon dioxide layer and a layer of undoped polycrystalline silicon. Aluminum is then diffused through windows formed in the mask. The mask has proven effective for relatively deep aluminum diffusion.

Abstract: A method of selectively doping a semiconductor body with aluminum impurities comprises the step of forming a layer of silicon dioxide which is thick enough so that during the diffusion a masking portion of aluminum oxide is formed therein. The aluminum oxide formed serves as a mask against the penetration of aluminum impurities through the remaining silicon dioxide therebelow.

Abstract: A method of diffusing conductivity modifiers into a semiconductor body is disclosed. The method employs an open system operated under a relatively high vacuum. A silicon alloy serves as the source of conductivity modifiers. Control of the dopant vapor pressure during diffusion is provided by controlling the composition of the silicon alloy. Additional control of the diffusion is provided by controlling the temperature of the system during diffusion and by regulating the vacuum drawn during diffusion.