Praburam Gopalraja

Nonlinear wave interaction in a magnetron plasma

Oscillations in the frequency range 10<f<300 MHz were measured using a Langmuir probe in a magnetron plasma. Dual probes were used to obtain wave number information. Three distinct peaks were observed that obeyed the nonlinear selection rule ω=ω0−ω1, where ω0 is the pump frequency, and ω and ω1 are the decay frequencies. The phase velocity of the highest frequency wave (f=262 MHz) was consistent with beam plasma oscillations driven by secondary electrons from the target. The nonlinearly driven lower frequency wave had a phase velocity enabling efficient Landau damping. The resulting transfer of energy from the secondary electrons to the waves to the bulk electrons may explain the enhanced ionization of sputtered material observed in some high power density magnetron discharges.

Sub-quarter micron metallization using ionized metal plasma (IMP) technology

Abstract Ionized metal plasma (IMP) technology has been developed for liners and wetting layer deposition of sub-quarter-micron devices. Numerical modeling showed the unique advantages of IMP source over ECR source and long throw sputtering in enhancing bottom coverage. TiN bottom coverage up to 70% were demonstrated. The deposition rate, uniformity, bottom coverage and film stress were optimized by tuning rf and dc powers, process pressure and bias power. The TiN film microstructure such as crystal orientation and grain size was controlled by process parameters. An IMP TiN x ( x x wetting layer. The via resistance was improved by IMP Ti deposition.

Advanced Cu barrier/seed development for 65nm technology and beyond

A novel PVD sputtering source has been developed based on a high power-density concept. The new sputtering source dramatically increases the metal ion traction which improves TaN/Ta barrier and Cu seed step coverage and gap fill capability in Cu metallization. Successful ECP gap fill has been achieved on the most aggressive features currently available - 0.08/spl mu/m 6:1 aspect ratio vias - when a 300/spl Aring/ Cu seed layer is deposited with this new source. Electrical test results based on the testing structure of 90nm technology node including parametric and stress migration, are equivalent or better than current processes. The new source will further extend the lifetime of PVD in the IC industry.