A micromachined specimen with a test section only 150-μm thick was developed for investigating subcritical crack growth in silicon. Crack growth rates in the range 10−4–10−10 m/s were measured as a function of applied stress intensity (v–K curves) during tests in humid air and dry nitrogen lasting up to 24 h. The fracture toughness, KIc of {110} silicon was also measured at 1.15 ± 0.08 MPa m1/2. While some evidence MPa-m1/2 of subcritical crack growth appeared to occur in the region 0.9 KIc < K > 0.98 KIc, the extremely high crack growth exponent (n 100) and the high ratio of the apparent stress corrosion threshold, KIscc, to the fracture toughness, KIscc/KIc > 0.9, suggests that no clear evidence exists for a stress corrosion process in silicon exposed to humid air.

Sub-90 nm device design presents challenges for lowering thermal budget as well as depositing uniform and conformal thin films for front-end-of-line silicon nitride applications. Among other low-temperature precursors for silicon nitride film deposition, bis͑tertiary-butylamino͒silane ͑BTBAS͒ has gained acceptance for critical applications such as spacer. This paper describes BTBAS based silicon nitride film deposition process optimization for spacer and etch stop applications. The single-wafer chamber design can control and tune the film with respect to deposition rate, film composition, wet etch rate, and film mechanical stress by adjustment of process conditions such as temperature, pressure, and gas flow rates. Computational flow and thermal simulations are employed to optimize chamber design to achieve uniform thin films.

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