The effects of the process parameters on the electrical and microstructure characteristics of the CrSi thin resistor films: part I

Abstract

The effects of process parameters, such as target composition, sputtering pressure, reactive gas partial pressure, deposition rate, and anneal temperature, on the electrical and microstructure characteristics of CrSi thin resistor films in very large scale integrated circuits (VLSI) application were investigated in this paper. It was observed that the higher metallic target composition, lower deposition rate, lower nitrogen partial pressure, and higher anneal temperature shift the temperature coefficient of resistance (TCR) to the positive direction. The relationships between TCR and anneal temperature, TCR and nitrogen partial pressure, and TCR and anneal environment were studied. Transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were conducted to explore the microstructure of the films; and the in situ anneal TEM analysis was performed to study the change of the microstructure of the films during anneal. The TEM images show that CrSi films from sputtering have typical cermet film microstructure which consists of darker ‘island’ regions embedded in lighter ‘boundary medium’ regions. When the anneal temperature is lower than 700°C, the microstructure remains largely unchanged as the temperature increases. At 700°C, the diffraction pattern from the pure Ar sputtered sample indicates that a change is occurring at 700°C. No such change was observed in the reactive sputtered sample at the same temperature.