Effect of Thermal ramping rate on defect formation in oxygen-implanted silicon-on-insulator material

Abstract

Integrated circuits on SIMOX (Separation by IMplantation of OXygen) have higher speed, radiation hardness, and higher temperature capability. Defects in the top Si layer inhibit bipolar applications and may affect CMOS(Complementary Metal-On-Semiconductor) device yield, operation and reliability. As-implanted SIMOX has many types of defects, including short stacking faults(SFs), multiply faulted defects(MFDs), and {113} defects. In annealed SIMOX, new defects form during the ramping cycle. The effect of thermal ramping rate on the development of new defects has received only limited study. In this work, the effects of rapid thermal annealing(RTA) and thermal ramp rate on defect density and structural change were studied.Two set of samples were prepared with different oxygen doses. First, one set of (100) Si wafers was implanted with a high dose of 1.8×l018cm−2 at 200 KeV at 620°C. A rapid thermal anneal(RTA) wafer was obtained from a lamp anneal for 1 minute at 1320°C using a ramp rate of 50°C/sec. A portion of this sample was then conventionally annealed in a tube furnace for 5 hours at 1320°C. Another set of (100) Si wafers was implanted with a low dose of 3×l015cm−2 at 25°C. Different samples were then annealed at 1250°C for 30 sec using three ramp rates of 50°C/sec, l°C/sec and 0.1°C/sec. Cross-sections of the samples were studied with conventional transmission electron microscopy (CTEM) at 200 KeV.