| 摘要 |
<P>PROBLEM TO BE SOLVED: To increase memory capacity of an SRAM without increasing the number of MISFETs. <P>SOLUTION: In a first n-channel-MISFET forming region nMIS1, for example, an impurity that gives p-type conductivity is introduced to form a p<SP>-</SP>-channel region 6, and the impurity that gives p-type conductivity is again introduced to form a p<SP>+</SP>-channel region 8. Then, by forming a gate electrode 11 and n-type semiconductor regions 14, an n-channel MISFET is formed, wherein the MISFET has a channel region where different impurity concentrations coexist underneath the gate electrode 11. As a consequence, the MISFET has two threshold voltages consisting of a relatively high threshold voltage and a relatively low threshold voltage. <P>COPYRIGHT: (C)2004,JPO |
