United States Patent 3,532,563
October 6, 1970
Doping Of Semiconductor Surfaces
Filed March 19, 1968
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
|Figure descriptions: cover graphic
- 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.
3,084,079 04/1963 Harrington
3,415,648 12/1968 Certa
3,474,718 10/1969 Guthrie