Paper PS-ThP11
Investigation of the Plasma Parameters and Plasma Process-Induced Damage in Physical Vapor Deposition

Thursday, October 21, 2010, 6:00 pm, Room Southwest Exhibit Hall

The introduce of the high K and metal gate enables significant gate leakage reduction (>100x) with excellent transistor performance. Physical vapor deposition process plays an important role in its manufacturing process because of its film composition tunability, excellent step coverage and thin film uniformity. However there are growing concerns about the potential process damage induced by the physical vapor deposition process since in some cases these films are directly deposited on thin (~20A) high k films. It is well known that PID can be classified into three categories: charging damage by plasma non-uniformity, bombardment damage by high energy ions, neutrals, and electrons, and radiation damage from plasma emission.In this paper, we mainly focus on high energy components in plasma itself and the process induced damage caused by the plasma non-uniformity. Both the discharge plasma properties (such as ne , Te, target voltage , ion energy etc) and their correlations to the potential plasma process induced damage were discussed. Two types of PVD chamber designs were evaluated in this study. One is a short throw rf PVD chamber which has both RF and DC power capability on the sputtering target. Another one is a long throw dc sputtering chamber with a special high ionization magnetron. Ti target material is used in this study. Discharge plasma parameters such as (plasma density ne, electron temperature Te, and plasma potentials Vpl) were monitored by a Langmuir probe inserted into the discharge cavity. The corresponding neutral and ion energy were further derived based on the measured target voltage and wafer self-induced dc bias. The plasma uniformity is characterized by an ion current probe biased at the ion saturation region. Two test vehicles: the 'Spiders ' wafer with different ANT ratios and MOS cap were used to quantify the plasma process induced damage.

Langmuir probe studies show that the rf plasma density increases linearly with the rf power while

the electron temperature remains constant in RF PVD chamber. Very high metal ionization was achieved as a result of the high plasma density by high rf power and high pressure ( >50mT)operation. Interestingly, no plasma process induced damage were observed by RF PVD Chamber under a broad range of process conditions even with different ion energy.On the other hand, with the dc high ionization (magnetron with a UB>3.5) operation,significant plasma damage was observed under most conditions. The damage was later correlated to the plasma non-uniformity.These results clearly demonstrates that plasma non-uniformity needs to be optimized

for any PVD hardware for the damage sensitive applications.