The improvement of MOSFET performance by the optimization of STI HDP-CVD integration process

• Plasma charging damage on gate oxide is a key factor to degrade Vt performance.
• H2 plasma produces low sputtering rate to reduce plasma charging damage.
• The Vt performance has an inversely proportional relationship to sputtering rate.
• Both NMOSFET and PMOSFET are improved by optimized HDP-CVD process.

The integration process of shallow trench isolation (STI) deposition was systematically investigated by using high-density plasma chemical vapor deposition (HDP-CVD). Two sputtering agents, Ar and H2, were utilized with various plasma RF power conditions. The STI HDP-CVD process consisted of two steps, including liner oxide and main gap-fill depositions. For the liner oxide deposition, the usage of Ar plasma was more favorable than H2 plasma because the drift of hydrogen-ions was detrimental for the electrical property of gate oxide. In the gap-fill process, H2 plasma with high bias RF power efficiently reduced plasma charging damage (PCD) on gate oxide due to its low sputtering rate and densely filled STI. The gap-fill capability and PCD were improved by the optimized condition of STI HDP-CVD process.

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