In addition, focus on N-type impurity diffusion region

**16**
*n *in tap cell

**2**C disposed in cell array A

**2**. N-type impurity diffusion region

**16**
*n *functions as a well potential supply region that supplies well potential to N-type well region NW of cell array A

**2**. In addition, dummy gates

**17**
*a *and

**17**
*b *are respectively disposed, as the first and the second adjacent gates, in both sides of N-type impurity diffusion region

**16**
*n *in the horizontal direction as the first well potential supply region. Gate electrode

**17**
*c *is closely disposed as the third adjacent gate in the opposite side to N-type impurity diffusion region

**16**
*n *in the side of dummy gate

**17**
*a*, and gate electrode

**17**
*d *is closely disposed as the fourth adjacent gate in the opposite side to N-type impurity diffusion region

**16**
*n *in the side of dummy gate

**17**
*b*. Furthermore, N-type impurity diffusion region

**18**
*n *is formed between dummy gate

**17**
*b *and dummy gate

**17**
*d *as a second well potential supply region.