United States Patent 3,532,563
October 6, 1970

Doping Of Semiconductor Surfaces
Milton Genser

Filed March 19, 1968
Image of US PATENT 3,532,563

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 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.

 Citations [54]:
3,084,079 04/1963 Harrington 3,415,648 12/1968 Certa 3,474,718 10/1969 Guthrie
National Museum of American History
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