For the next generation of semiconductor devices, new metal deposition technologies (such as Cu and Ti chemical vapor deposition) are being developed. As very large-scale integrated fabrication becomes more highly integrated, the size of contact/via holes must shrink, producing higher aspect ratios. These geometries create major difficulties in obtaining acceptable step coverage of the barrier/glue layer within the contact/via holes. A new technology has been developed, called long-throw sputter (LTS), for achieving acceptable step coverage particularly for geometries below 0.5 μm without employing collimators in the system. LTS (patent pending) provides more than 40% bottom coverage of barrier metal films in 0.35 μm contact holes with 3.0 aspect ratio while maintaining a high deposition rate and acceptable film uniformity. Additionally, LTS may facilitate Al alloy flow and/or reflow application.

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This paper describes a high-performance and highly reliable GaAs field-effect transistor (FET) with a new gate structure employing the stepped gate recess combined with a multirefractory metal gate. This gate structure allows the simultaneous increase of maximum channel current and gate-drain breakdown voltage (V gdo) of the FET and thus improves significantly its output power (P o) and power-added efficiency (ηadd). The resultant high V gdo with highly stable gate Schottky characteristics and a novel surface stabilization prior to plasma-SiN passivation effectively suppress both catastrophic and gradual failures. The four-chip internally matched device (4×12.6 mm) has delivered P o of 20 W at 1 dB gain compression with 39% ηadd over 3.5 to 4.2 GHz. Sufficient reliability of the 20 W device available for satellite use has been assured by comprehensive reliability tests.

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