Stacked polycrystalline silicon film of high and low conductivity layers
AssigneeHitachi, Ltd.
InventorsYasuo Wada, Hiroo Usui, Makoto Ohkura, Masanobu Miyao, Masao Tamura, Takashi Tokuyama
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Abstract
A polycrystalline silicon film is implanted with an impurity in large amounts and is heated to be annealed, whereupon it is irradiated with a laser beam to be annealed. Thus, a polycrystalline silicon film of very low resistivity consisting of a second layer whose activated impurity concentration is equal to or below a solid solubility and a first layer whose activated impurity concentration is above the solid solubility is formed.
Claims10
A polycrystalline silicon film comprising a second layer and a first layer formed on the second layer, the second layer being formed by impurity doping and thermal annealing prior to forming the first layer, said second layer having an activated impurity concentration that is not higher than a solid solubility, and the first layer being formed on said second layer and having an activated impurity concentration that is higher than the solid solubility, whereby a polycrystalline film having a low resistivity is formed.
A polycrystalline silicon film comprising a second layer whose activated impurity concentration is not higher than a solid solubility but whose activated impurity concentration is formed by impurity doping and thermally annealing the second layer to form an activated impurity concentration nearly equal said solid solubility, and a first layer which is formed on said second layer and whose activated impurity concentration is higher than the solid solubility, whereby a polycrystalline film having a low resistivity is formed.
Dependencies are inferred from the claim text.