Patent ID: 11864368
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A static random access memory (SRAM) cell comprising:
a substrate having a first p-well and an n-well bordering the first p-well;
a first semiconductor fin extending within the first p-well;
a first gate structure extending across the first semiconductor fin and forming a first write-port pull-down transistor with the first semiconductor fin;
a second semiconductor fin extending within the n-well;
a second gate structure extending across the second semiconductor fin and forming a first write-port pull up transistor with the second semiconductor fin, wherein a channel region of the first write-port pull-down transistor has a higher p-type doping concentration than a channel region of the first write-port pull up transistor;
a third semiconductor fin extending within a second p-well spaced from the first p-well by the n-well, wherein the second gate structure extends across the third semiconductor fin and forms a second write-port pull-downn type transistor with the third semiconductor fin;
a fourth semiconductor fin extending within the first p-well and forming a read-port pull-down transistor with the first gate structure, wherein a p-type doping concentration of a channel region of the second write-port pull-down transistor is lower than the p-type doping concentration of the channel region of the first write-port pull-down transistor and higher than a p-type doping concentration of a channel region of the read-port pull-down transistor; and
a fourth gate structure extending across the first semiconductor fin and forming a first write-port pass-gate transistor with the first semiconductor fin, wherein a channel region of the first write-port pass-gate transistor has a p-type doping concentration lower than the p-type doping concentration of the channel region of the first write-port pull-down transistor.