Electrical Characterization of Silicon-on-Insulator Wafers Using Photo-Conductance Decay (PCD) Method

Abstract

In this work the photo-conductance decay (PCD) technique is used to measure the effective carrier lifetime in 160 nm-180 nm thick active layers of silicon-on-insulator (SOI) substrates both SIMOX and bonded. Study was carried out using 405 nm excitation wavelength featuring 200 nm absorption depth in silicon which was selected to coincide with the thickness of the active layers in the SOI wafers studied. The results obtained indicate the effectiveness of PCD methodology adopted for this study in the measurements of the minority carrier lifetime in Si active layers in SOI substrates. They demonstrate differences between PCD characterization of bulk and SOI wafers which are related to the confinement of the depletion region within the Si active layer in the latter case making its electrical properties less sensitive to the variation of the surface chemical condition. On the other hand, the process related physical changes in the SOI surface morphology were readily detectable by PCD measurements. Furthermore, the specific outcome of this investigation is the result indicating higher minority carrier lifetime in the Si active layer of bonded SOI wafers as compared to SIMOX wafers used in this study.

Electrical Characterization of As-Processed Semiconductor Surfaces - Invited Paper

“…However, longer etch time results in significant alteration of the m-c Si surface resulting in the gradual decrease of the minority carrier lifetime. To further investigate performance of the PCD method in the characterization/monitoring of the SOI wafers surface a physical damage to the SOI surfaces was inflicted by Ar + ion etching [8]. As the variations in the PCD decay profiles in Fig.…”

The concept of electrostatic doping and related devices

“…The HP diode serves for evaluating the carrier lifetime, which reflects the material quality and governs the performance of bipolar and power devices. Unfortunately, the well-known optical and capacitance techniques [37]- [40] prove inefficient in ultrathin fully depleted films. We proposed a simple method which consists in measuring the anode voltage corresponding to the transition between the recombination and diffusion regimes [40].…”

“…Unfortunately, the well-known optical and capacitance techniques [37]- [40] prove inefficient in ultrathin fully depleted films. We proposed a simple method which consists in measuring the anode voltage corresponding to the transition between the recombination and diffusion regimes [40]. Simulations of P-N diodes with variable physical doping teach us that the recombination IR and diffusion ID currents are equal for an ideality factor n = 1.3 [41].…”