Thermal Agglomeration of Ultrathin SOI and SSOI Films: A Quantitative Stability Study and Physical Model to Guide Ultrathin SOI Process Design

Abstract

We present the results of a controlled experimental study of the thermal agglomeration of (100)-oriented ultra-thin SOI films along with a surface-energy-driven physical model for SOI agglomeration to guide ultra-thin SOI process design. Through a UHV annealing study, the SOI agglomeration edge initiation time and edge propagation velocity were determined as a function of SOI thickness and annealing temperature for bonded and SiMOX SOI films. SiMOX SOI and strained SOI films were studied and shown to have nearly identical agglomeration behavior to bonded SOI films, clearly indicating that SOI agglomeration is not a stress-driven phenomenon. An ultra-thin SOI defect study was also performed in parallel with this agglomeration study to identify the defect responsible for bulk SOI agglomeration initiation. HF defects, dislocations, and stacking faults were ruled out and initial evidence indicates that defects at the top Si/buried SiO2 interface may be responsible.