| 摘要 |
PROBLEM TO BE SOLVED: To reduce the density of crystal defects within a polycrystalline semiconductor film and thereby increase its impurity activating rate by heat-treating the polycrystalline semiconductor film in an oxide atmosphere, after an impurity is introduced into the polycrystalline semiconductor film, so that oxidation and impurity activation are implemented simultaneously. SOLUTION: In a dual gate structure CMOS transistor semiconductor device, the average crystal grain size of a polycrystalline silicon film constituting gate electrodes 306a and 306b is set to 50 nm or higher, more preferably to 100 nm or higher. As a result, the density of crystal defects within the polycrystalline silicon film, which is a component material of the device, can be suppressed to about 1×1018 cm-3 or lower, whereby the amount of an impurity which is not activated while trapped by the crystal defects can be suppressed for the electrodes 306a and 306b to improve the impurity activating rate. This makes the activated impurity concentration at a region adjacent to the gate insulated film 305 to a level of about 1×1019 cm-3 or higher, and the electrodes 306a and 306b will not be depleted.
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