Sram cell with t-shaped contact

Abstract

An integrated circuit containing an array of SRAM cells with T-shaped contacts in the inverters, in which drain connecting segments may extend beyond gate connecting segments by a distance greater than 10 percent of a separation distance between ends of opposite drain connecting segments. The drain connecting segments may also extend beyond gate connecting segments by a distance greater than one-third of the width of the gate connecting segments. A process of forming an integrated circuit containing an array of SRAM cells with T-shaped contacts in which drain connecting segments may extend beyond gate connecting segments by a distance greater than 10 percent of a separation distance between ends of opposite drain connecting segments. A process may also form the drain connecting segments to extend beyond gate connecting segments by greater than one-third of the width of the gate connecting segments.

1 . A process of forming an integrated circuit containing an array of SRAM cells, comprising the steps:
 providing an integrated circuit containing a first driver/passgate active strip having a first conductivity type, a second driver/passgate active strip having said first conductivity type, a first load active strip having a second conductivity type opposite from said first conductivity type, a second load active strip having said second conductivity type, a first inverter gate that crosses said first driver/passgate active strip over a channel region of a first driver transistor and crosses said first load active strip over a channel region of a first load transistor, and a second inverter gate that crosses said second driver/passgate active strip over a channel region of a second driver transistor and crosses said second load active strip over a channel region of a second load transistor;   performing a first photolithographic exposure step to form a first drain connecting segment patterned area of a first T-shaped contact and to form a second drain connecting segment patterned area of a second T-shaped contact, such that said first drain connecting segment patterned area overlaps said first driver/passgate active strip over a drain node of said first driver transistor and also overlaps said first load active strip over a drain node of said first load transistor, and said second drain connecting segment patterned area overlaps said second driver/passgate active strip over a drain node of said second driver transistor and overlaps said second load active strip over a drain node of said second load transistor;   performing a second photolithographic exposure step to form a first gate connecting segment patterned area of said first T-shaped contact and to form a second gate connecting segment patterned area of said second T-shaped contact, such that said first gate connecting segment patterned area intersects said first drain connecting segment patterned area, and said second gate connecting segment patterned area intersects said second drain connecting segment patterned area;   forming said first T-shaped contact in an area defined by said first drain connecting segment patterned area and said first gate connecting segment patterned area, such that said first T-shaped contact includes a first drain connecting segment in an area defined by said first drain connecting segment patterned area, said first T-shaped contact includes a first gate connecting segment in an area defined by said first gate connecting segment patterned area, and said first T-shaped contact provides an electrical connection between said drain node of said first driver transistor, said drain node of said first load transistor, and said second inverter gate; and   forming said second T-shaped contact concurrently with said first T-shaped contact in an area defined by said second drain connecting segment patterned area and said second gate connecting segment patterned area, such that said second T-shaped contact includes a second drain connecting segment in an area defined by said second drain connecting segment patterned area, said second T-shaped contact includes a second gate connecting segment in an area defined by said second gate connecting segment patterned area, and said first T-shaped contact provides an electrical connection between said drain node of said second driver transistor, said drain node of said second load transistor, and said first inverter gate;   wherein an end of said first drain connecting segment over said drain node of said first load transistor extends beyond said first gate connecting segment by a distance greater than 10 percent of an end separation distance between ends of said first drain connecting segment and said second drain connecting segment, and an end of said second drain connecting segment over said drain node of said second load transistor extends beyond said second gate connecting segment by a distance greater than 10 percent of said end separation distance between ends of said first drain connecting segment and said second drain connecting segment.   
     
     
         2 . The process of  claim 1 , in which intersecting edges of said first drain connecting segment and said first gate connecting segment are substantially perpendicular, and intersecting edges of said second drain connecting segment and said second gate connecting segment are substantially perpendicular. 
     
     
         3 . The process of  claim 2 , further comprising:
 forming a first passgate gate over said first driver/passgate active strip, an area of said first driver/passgate active strip overlapped by said first passgate gate forming a channel region of a first passgate transistor of said SRAM cell; and   forming a second passgate gate over said second driver/passgate active strip, an area of said second driver/passgate active strip overlapped by said second passgate gate forming a channel region of a second passgate transistor of said SRAM cell, such that;   an outer edge of said channel region of said first passgate transistor extends beyond an outer edge of said channel region of said first driver transistor by a distance greater than half said distance by which said end of said first drain connecting segment extends beyond said first gate connecting segment; and   an outer edge of said channel region of said second passgate transistor extends beyond an outer edge of said channel region of said second driver transistor by a distance greater than half said distance by which said end of said second drain connecting segment extends beyond said second gate connecting segment.