Semiconductor device and design method thereof

1. A semiconductor device, comprising:

a plurality of first cells having a first cell height, and a plurality of second cells having a second cell height, wherein

the first cells and the second cells are formed on the same semiconductor substrate,

each of the first cells has

a first element isolation region formed so as to define a first element formation region in the semiconductor substrate,

a first MIS transistor of a first conductivity type including, over the semiconductor substrate, a first gate electrode that is formed so as to extend across the first element formation region in a direction of the first cell height, and a first source region and a first drain region of the first conductivity type that are formed in regions extending laterally below the first gate electrode in the first element formation region, and

a substrate contact region of a second conductivity type formed in the direction of the first cell height so as to face the first element formation region with the first element isolation region interposed therebetween,

the second conductivity type is opposite in polarity to the first conductivity type,

each of the second cells has

a second element isolation region formed so as to define a second element formation region in the semiconductor substrate,

a second MIS transistor of the first conductivity type including, over the semiconductor substrate, a second gate electrode that is formed so as to extend across the second element formation region in a direction of the second cell height, and a second source region and a second drain region of the first conductivity type that are formed in regions extending laterally below the second gate electrode in the second element formation region,

a power supply region of the first conductivity type formed in the direction of the second cell height so as to face the second element formation region with the second element isolation region interposed therebetween, and

a first extended region of the first conductivity type silicidated at a surface thereof, and provided between the power supply region of the first conductivity type and the second source region and interposed between portions of the second element isolation region, so as to connect the power supply region of the first conductivity type to the second source region, and

the first cell height is greater than the second cell height.

2. The semiconductor device of claim 1 , wherein

a contact plug is formed over the first source region, but is not formed over the second source region.

3. The semiconductor device of claim 1 , wherein

a length of a protruding portion of the second gate electrode in a gate width direction of the second gate electrode is greater than that of a protruding portion of the first gate electrode in a gate width direction of the first gate electrode, and

the protruding portion of the second gate electrode is a portion that protrudes beyond the second element formation region to a position on the second element isolation region, and the protruding portion of the first gate electrode is a portion that protrudes beyond the first element formation region to a position on the first element isolation region.

4. The semiconductor device of claim 1 , wherein

each of the first cells further has

a third element isolation region formed so as to define a third element formation region in the semiconductor substrate,

a third MIS transistor of the second conductivity type including, over the semiconductor substrate, a third gate electrode that is continuous with the first gate electrode and is formed so as to extend across the third element formation region in the direction of the first cell height, and a third source region and a third drain region of the second conductivity type that are formed in regions extending laterally below the third gate electrode in the third element formation region, and

a substrate contact region of the first conductivity type formed in the direction of the first cell height so as to face the third element formation region with the third element isolation region interposed therebetween, and

each of the second cells further has

a fourth element isolation region formed so as to define a fourth element formation region in the semiconductor substrate,

a fourth MIS transistor of the second conductivity type including, over the semiconductor substrate, a fourth gate electrode that is continuous with the second gate electrode and is formed so as to extend across the fourth element formation region in the direction of the second cell height, and a fourth source region and a fourth drain region of the second conductivity type that are formed in regions extending laterally below the fourth gate electrode in the fourth element formation region,

a power supply region of the second conductivity type formed in the direction of the second cell height so as to face the fourth element formation region with the fourth element isolation region interposed therebetween, and

a second extended region of the second conductivity type silicidated at a surface thereof, and provided between the power supply region of the second conductivity type and the fourth source region and interposed between portions of the fourth element isolation region, so as to connect the power supply region of the second conductivity type to the fourth source region.

5. The semiconductor device of claim 4 , wherein

a contact plug is formed over the third source region, but is not formed over the fourth source region.

6. The semiconductor device of claim 4 , wherein

a length of a protruding portion of the fourth gate electrode in a gate width direction of the fourth gate electrode is greater than that of a protruding portion of the third gate electrode in a gate width direction of the third gate electrode, and

the protruding portion of the fourth gate electrode is a portion that protrudes beyond the fourth element formation region to a position on the fourth element isolation region, and the protruding portion of the third gate electrode is a portion that protrudes beyond the third element formation region to a position on the third element isolation region.

7. The semiconductor device of claim 4 , wherein

a first gate contact formation region is formed in a region where the first gate electrode is continuous with the third gate electrode,

a second gate contact formation region is formed in a region where the second gate electrode is continuous with the fourth gate electrode, and

a length of the first gate contact formation region in the direction of the first cell height is greater than that of the second gate contact formation region in the direction of the second cell height.

8. A method for designing the semiconductor device of claim 1 , comprising the step of:

designing the semiconductor device by using the first cells when a ratio of a cell height to an interconnect pitch is higher than 8, and designing the semiconductor device by using the second cells when the ratio is 8 or less.