Ho Wai Lo

Ultraviolet laser repair of advanced semiconductor memory devices

Summary form only given. Fabrication of semiconductor memory devices, including dynamic random access memory (DRAM) and static random access memory (SRAM), relies upon laser repair. Laser repair of memory involves the single pulse severing of fuses to enable decoders to address redundant memory cells, thereby improving the wafer-level yield of useful die. The development of next generation memory devices, such as 1 gigabyte (GB) DRAM will utilize fuse sizes of less than 500 nm on link pitches of 1500 nm and smaller and utilize Cu and Al fuses. Current laser memory repair systems employ Q-switched diode-pumped Nd:YLF and Nd:YVO/sub 4/ lasers operating at 1.047 /spl mu/m and 1.343 /spl mu/m, respectively. Systems operating in the infrared are expected to encounter difficulty in repairing devices at this scale due to wavelength-induced spot size limitations. To overcome these difficulties, we have recently demonstrated the extension of laser memory repair to the ultraviolet region and at link severing rates as high as 20,000 Hz.