The LSA101LP laser spike anneal system from Ultratech, Inc. features a second low-power (LP) laser beam to enable low-temperature processing required for middle-of-line (MOL) applications.
The second dual-beam system, the LSA101HP, features a second high-power (HP) laser which enables longer dwell times required for some advanced front-end-of-line (FEOL) applications. Both dual-beam systems are field upgradable on the LSA101 platform.
In the LSA101 system, a single CO2 laser beam is used to heat the wafer surface from a substrate temperature of approximately 400C to the peak annealing temperature in the range 1100-1350C. In the LSA101LP system, a second low-power laser beam is incorporated to preheat the wafer, which enables the lower substrate temperatures required for MOL processes, such as nickel silicide formation. In addition, a new temperature measurement and control system has been developed to enable the lower peak temperatures required for these processes. For leading-edge logic nodes, the short time scale of millisecond annealing has been shown to minimize nickel silicide diffusion and leakage-related yield loss. For MOL applications, the maximum throughput of the system is an industry-leading 70wph.
For the LSA101 system, the primary CO2 beam is relatively narrow so that it generates dwell times on the order of 100s of microseconds. In Ultratech’s LSA101HP system, the second high-power laser creates a longer dwell time anneal on the order of 10msec. The combination of these two lasers leads to a unique temperature profile, which is comprised of a long dwell and short dwell anneal in a single process. There are numerous applications that can benefit from this kind of temperature profile, such as annealing end-of-range implant damage with minimal dopant diffusion. This application has the potential of replacing conventional rapid thermal processing (RTP) for junction activation in advanced logic nodes, where small devices cannot tolerate the dopant diffusion caused by the longer annealing times of RTP.
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