| 摘要 |
PROBLEM TO BE SOLVED: To obtain a reference voltage generating circuit which is less dependent on process variation and temperature change. SOLUTION: The channel impurities of channel dope domains 1, 2 are completely the same profiles, and are formed simultaneously. On a floating gate 13 composed of poly silicone, a control gate 5 composed of poly silicone is formed through a poly/poly layer film 6. The width of the floating gate 13 of the MOS transistor Q2 whose threshold voltage Vth is lower is W1, and the width of the floating gate 13 of the MOS transistor Q3 whose threshold voltage Vth is higher is Wh (Wh<W1). The difference of the threshold voltage Vth occurs only by the difference of the coupling coefficient CC, so that the difference of the threshold voltage Vth can be kept constant even the channel dope, the thickness of the oxidized gate films, or the film thickness of the poly/poly layer film 6 fluctuate.
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