Boron Enhanced Diffusion Due to High Energy Ion-Implantation and Its Suppression by Using RTA Process
- PDF / 338,796 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 93 Downloads / 213 Views
Abstract SIMS measurements revealed that high energy boron-implantation causes transient enhanced diffusion (TED) of a shallow dopant profile due to Si interstitials even for a relatively low dose of -2E13cm" 2. By systematic analysis, it is found that this anomalous diffusion is most significant in 700-800'C annealing, and it takes place in the initial stage (less than 30sec for 800*C) of annealing. Moreover, this anomalous diffusion is more considerable than the enhanced diffusion during oxidation (OED) in practical device fabrication processes. It is found that rapid thermal annealing (RTA) at 1000-1 100'C is effective for suppressing the transient enhanced diffusion and realizing a shallow channel profile for deep sub-micron devices. Introduction The high energy ion-implantation (HEI) process is a promising technology for well formation of deep sub-micron CMOS [1,2]. As compared with a diffused well, the process flexibility is increased because profiled wells can be easily fabricated for the optimization of many device characteristics independently, by employing multiple ion implantation. On the other hand, from the viewpoint of the device fabrication process, the process temperature tends to be decreased. As a result of this decrease of process temperature, the anomalous
diffusion caused by the ion-implantation damage becomes more pronounced. Regarding the anomalous diffusion phenomenon related with the point defects, oxidation enhanced diffusion (OED) and transient enhanced diffusion (TED) are well-known. It has been known that these anomalous diffusion phenomena are caused by the dopants which are paired with excess Si interstitial atoms [3,4]. These pairs can diffuse even in a low temperature annealing process. As a result, it can be observed as anomalous diffusion. This diffusion continues as long as the Si interstitial concentration exceeds the thermal equilibrium concentration. In order to realize high performance LSIs highly-controlled doping profiles are indispensable. Therefore, it is necessary to precisely control anomalous diffusion. In the device fabrication process, one of the most effective processes for generating Si interstitials is the ion-implantation process. So far, TED due to ion-implantation of relatively high dose range has been studied [3,4,5], however, there have been few reports in the case of relatively low dose, the order of -10 3cm"2 which is a practical dose range for well formation. In this work, we systematically studied the TED of boron caused by HEI with relatively low dose and investigated the effect of rapid thermal annealing (RTA) on the TED phenomenon.
319 Mat. Res. Soc. Symp. Proc. Vol. 354 01995 Materials Research Society
Experimental The substrates used in this experiment were 1E15cm"3 boron-doped, (100) silicon CZ wafers. After the wafers were oxidized in 750°C in steam ambient to obtain a 10nm-thick oxide film, 300keV or 1MeV boron ions (HEI) were implanted with a dose of 2E13cm 2 . Next, some of the wafers were rapidly annealed at various temperatures in N2 ambie
Data Loading...
