Abstract of the Disclosure

Semiconductor surfaces are doped with an aqueous solution of the doping chemical in a carrier of a water soluble polymer having a molecular weight of over about 1000. This dopant can include a photosensitive compound, such as a water soluble dichromate which produces insolubility upon exposure to light.

• Figure 1 depicts a cross-sectional schematic and exaggerated view of a masked silicon semiconductor wafer mounted on a chuck in a vacuum chamber, with dopant applied.
• Figure 2 illustrates a similar view after spinning whereby a dopant film is spread over the mask.
• Figure 3 presents a similar view (without the chuck) after heating of the masked wafer to affect doping of the exposed wafer surfaces.
• Figure 4 shows a similar view (as in Figure 3) of a silicon wafer coated with a spun film of dopant carrying a photosensitive chemical.
• Figure 5 illustrates the wafer of Figure 4 with a mask applied thereover and the exposed doped wafer portions irradiated with ultra-violet light.
• Figure 6 presents the wafer of Figure 5 after development and washing off of the unexposed dopant.
• Figure 7 depicts the wafer of Figure 6 after heating to permit the dopant to diffuse into the doped areas.

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3,084,079  04/1963  Harrington
3,415,648  12/1968  Certa
3,474,718  10/1969  Guthrie