AVS 52nd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM1-TuM

Paper EM1-TuM3
Interstitial Oxygen Related Defects and Current Leakage in UMOSFET on Epi/As++ Structure

Tuesday, November 1, 2005, 9:00 am, Room 310

Session: Defects, Interfaces, and Surface Passivation in Electronic Materials
Presenter: Q. Wang, Fairchild Semiconductor
Authors: Q. Wang, Fairchild Semiconductor
M. Daggubati, Fairchild Semiconductor
H. Paravi, Fairchild Semiconductor
R. Yu, Lawrence Berkeley National Laboratory
X. Zhang, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
Interstitial oxygen (O@sub i@) related defects and current leakage in UMOSFET on Epi/As++ structure has been investigated. The devices fabricated on heavily arsenic doped wafer with poly-silicon backside exhibited an increased yield loss in reverse current leakage with increasing O@sub i@ concentration in the wafer. For the wafers with the same O@sub i@ content, the leakage yield loss increases with decreasing device geometry. This leakage yield loss was attributed to the O@sub i@ related defects in active region (well junction). Transmission electron microscopy (TEM) study revealed, in the well junction region, the existence of extrinsic stacking faults and half-hexagonal dislocation punch-through defects, characteristic of oxygen precipitation. Defects created by the heavy body boron implantation seem to enhance O@sub i@ precipitation in the active region. In addition, the O@sub i@ is also found to diffuse to the interface of the poly-silicon layer and bulk silicon and precipitate out. This precipitation may consume the poly layer and reduce the gettering effect of poly silicon, which also leads to an O@sub i@ dependent current leakage. Similar experiments carried out with damaged backside wafers showed that current leakage yield loss was independent of O@sub i@ in the wafer and was low in general. The detailed TEM work indicated that the O@sub i@ did precipitate out in the bulk close to the back surface. The O@sub i@ precipitates may result in an intrinsic gettering and thus improve the current leakage yield. This comparative study between poly-silicon and damaged back-surfaces indicates that for heavily arsenic doped silicon wafers, intrinsic gettering is much better than extrinsic gettering due to the facts discussed above.