Title :
Monitoring of low-dose ion implantation in silicon
Author :
Hara, Tohru ; Hagiwara, Hiroyuki ; Ichikawa, Ryuji ; Nakashima, Shinichi ; Mizoguchi, Koji ; Smith, W. Lee ; Welles, C. ; Hahn, S.K. ; Larson, L.
Author_Institution :
Dept. of Electr. Eng., Hosei Univ., Tokyo, Japan
Abstract :
Monitoring of low-dose arsenic or boron ion implantation (doses: 5*10/sup 10/ to 1*10/sup 13/ cm/sup -2/) in silicon, which is required for threshold voltage control of MOS transistors, is studied. The thermal-wave (TW) signal intensity decreases monotonically with decreasing dose. The lowest detection limit for As/sup +/ and B/sup +/ implantations is 5*10/sup 10/ and 1*10/sup 11/ cm/sup -2/, respectively. Correlation of the TW signal intensity versus damage density, TW intensity versus dose, and laser Raman intensity versus dose is obtained. The TW intensity is also correlated with the sheet conductance, and the threshold voltage of the transistor. Therefore, this technique is useful as a nondestructive, highly sensitive dose monitor for low-dose implantation to achieve tight threshold voltage control in MOS transistors.<>
Keywords :
Raman spectra of inorganic solids; arsenic; boron; elemental semiconductors; insulated gate field effect transistors; ion implantation; semiconductor doping; silicon; thermoreflectance; voltage control; MOS transistors; Si:As/sup +/; Si:B/sup +/; damage density; highly sensitive dose monitor; ion implantation detection; laser Raman intensity; low-dose ion implantation; lowest detection limit; nondestructive monitoring; optical reflectance; sheet conductance; thermal-wave signal intensity; threshold voltage control; Crystals; Ion implantation; MOSFETs; Monitoring; Optical modulation; Raman scattering; Silicon; Spectroscopy; Threshold voltage; Voltage control;
Journal_Title :
Electron Device Letters, IEEE
