Abstract: A synchronous circuit, such as an SRAM, a DRAM or a programmable logic device, has internal circuitry, a master input latch clocked by a master clock generator, and a slave output latch clocked by a slave clock generator. The master input latch is rendered transparent prior to the start of system setup time so that information input signals can pass through the master input latch and undergo processing in the circuitry prior to the start of a system cycle. After correct and stable information output signals are generated by the internal circuitry, these signals are latched into the slave output latch as correct and stable output information. The master latch may be clocked from the latched to the transparent state before the slave latch is clocked from the transparent to the latched state, provided that the time period between these two transitions is less than the minimum processing time of the internal circuitry.

Abstract: An MOS transistor for use in an integrated circuit is fabricated with a self-aligning contact and interconnect structure which allows for higher packing density. Self-aligning source and drain contacts overlap the gate but are prevented from a short circuiting to the gate by oxide insulation between the source/drain contacts and the gate, and a layer of silicon nitride above the gate. Contacts to the gate are made on top of the gate over the active region of the transistor because the source and drain regions are protected by a hardened layer of photoresist during etching of insulation to expose the gate contact. Source, drain and gate contacts are protected by a layer of titanium silicide so that interconnects are not required to completely cover these areas. Low resistance interconnects are formed of doped polysilicon covered by titanium silicide encapsulated by a thin film of titanium nitride.