Transparent Quartz Substrate Research Articles

Nucleation effects in visible-laser chemical vapor deposition

A low power, focused, argon ion laser beam ∼514.5 nm has been used to controllably and reproducibly deposit micron-size metallic films on transparent glass and quartz substrates. Film growth proceeds via the pyrolytic decomposition of organometallic molecules on nucleation sites. The nucleation sites can be created over the entire substrate by flood exposure with deep ultraviolet light in the presence of organometallic vapor or in micron size areas by forming an initial deposit and then scanning the substrate across the focused laser beam. The latter nucleation technique has been extended to the deposition of metal on chrome-on-glass photomasks. Here metal deposition proceeds in three distinct time periods: surface modification (fast), nucleation (slow), and film growth (fast). The visible-laser chemical vapor deposition technique has been used to demonstrate the repair of defects in photomasks with a resolution approaching 1 μm.

Display Quality SOI by Recrystallization of Bridged Silicon Islands on Quartz

ABSTRACTArrays of single crystal thin film silicon islands were prepared on fused quartz substrates by a zone melting recrystallization of bridged island patterns of poly-Si. A scanning graphite strip heater technique was used, with the Si islands connected (“bridged”) in the scanning direction by narrow Si strips. These strips generated a self-seeding effect in the crystalline growth, and the recrystallized Si islands were good quality SOI with <100> orientation as shown by x-ray and etch-pit analysis. Protuberances, film cracking and impurity segregation were greatly suppressed in this bridged island SOI as compared to defects normally observed in recrystallized continuous Si films on quartz. MOSFETs were fabricated in the SOI islands, using n-channel enhancement mode devices with a gate length of 5μm and a gate width of 50μm. The average carrier mobility measured on these SOI devices was 470 ± 70 cm2/V.s, which was twice as high as the mobility measured in MOSFETs fabricated concurrently in SOS. Good MOSFETs in the SOI islands showed a switching ratio of about 107 at 6V and a leakage of less than 2pA/μm. These results indicate that high performance drive circuits for liquid crystal displays can be fabricated in SOI recrystallized from bridged island patterns on transparent quartz substrates.