Identification of Yield-Limiting Defects in a 0.5 Micron, Shallow Trench211 Isolation Technology

摘要

During the development and qualification of a radiation-hardened, 0.5 (micro)m211u001eshallow trench isolation technology, several yield-limiting defects were 211u001eobserved. The 256K (32K x 8) static-random access memories (SRAMs) used as a 211u001etechnology characterization vehicle had elevated power supply current during 211u001ewafer probe testing. Many of the die sites were functional, but exhibited 211u001equiescent power supply current (I(sub DDQ)) in excess of 100 (micro)A, the 211u001epresent limit for this particular SRAM. Initial electrical analysis indicated 211u001ethat many of the die sites exhibited unstable I(sub DDQ) that fluctuated rapidly. 211u001eWe refer to this condition as 'jitter'. The I(sub DDQ) jitter appeared to be 211u001eindependent of temperature and predominantly associated with the larger 256K 211u001eSRAMs and not as prevalent in the 16K SRAMs (on the same reticle set). The root 211u001ecause of failure was found to be two major processing problems: salicide bridging 211u001eand stress-induced dislocations in the silicon islands.