Decoupling capacitor cell, cell-based ic, and portable device

Abstract

A decoupling capacitor cell includes: a first decoupling capacitor formed by only a pMOS transistor; and a second decoupling capacitor formed by two metal layers. The decoupling capacitor cell is arranged in an unused region not occupied by basic cells in a cell-based IC and is connected to a power wiring and a ground wiring.

1 .- 13 . (canceled) 
     
     
         14 . A decoupling capacitor cell comprising:
 a first decoupling capacitor formed by a pMOS transistor; and   a second decoupling capacitor formed by two metal layers, wherein the decoupling capacitor cell is connected to a power wiring and a ground wiring.   
     
     
         15 . A cell-based IC comprising:
 a semiconductor substrate;   a plurality of basic cells which is formed on the semiconductor substrate to have a plurality of semiconductor devices and internal wirings, and has a predetermined function provided by connecting the semiconductor devices using the internal wirings;   a wiring region which is formed on the semiconductor substrate and has an external wiring to connect the basic cells; a ground wiring and a power wiring configured to supply power to the semiconductor devices;   a first decoupling capacitor which is formed by a pMOS transistor on the semiconductor substrate; and   a second decoupling capacitor which is constituted by two metal layers formed on the semiconductor substrate,   wherein a decoupling capacitor cell which is formed by the first and second decoupling capacitors is connected to the power wiring and the ground wiring.   
     
     
         16 . The cell-based IC of  claim 15 , wherein the second decoupling capacitor includes:
 decoupling capacitor members which are constituted by a first layer of metal formed on the semiconductor substrate and extends in a plane direction parallel to the semiconductor substrate; and   a power rail including the power wiring and the ground wiring, wherein the power rail is constituted by a second layer of metal formed on the semiconductor substrate to face a portion of the decoupling capacitor member.   
     
     
         17 . The cell-based IC of  claim 16 , wherein the power wiring and the ground wiring of the power rail for the decoupling capacitor cell are disposed in parallel to each other. 
     
     
         18 . The cell-based IC of  claim 16 , wherein the decoupling capacitor members have a form of a comb tooth having a plurality of unevenness formed in the plane direction. 
     
     
         19 . The cell-based IC of  claim 16 , wherein the decoupling capacitor members have a form of a strip. 
     
     
         20 . The cell-based IC of  claim 16 , wherein the decoupling capacitor members are constituted by a combination of a form of a comb tooth having a plurality of unevenness formed in the plane direction and a form of a strip. 
     
     
         21 . The cell-based IC of  claim 16 , wherein the decoupling capacitor members have a form of a fishbone having a plurality of unevenness formed in the plane direction. 
     
     
         22 . The cell-based IC of  claim 15 , wherein the first decoupling capacitor and the second decoupling capacitor are connected in parallel between the power wiring and the ground wiring. 
     
     
         23 . A portable device comprising the cell-based IC of  claim 15 .