Damage formation and annealing studies of low energy ion implants ...
Damage formation and annealing studies of low energy ion implants ... Damage formation and annealing studies of low energy ion implants ...
For the sample annealed at 650 °C, where there is a major change in the MEIS profile the differences between the results from the two techniques are clearly visible. The SIMS profile shows a great deal of extra As from a depth of 4 – 12 nm and this, as argued above, must represent substitutional As. For the 0 – 4 nm depth range the SIMS profile is higher than the MEIS profile. This is most likely due to the comparatively large uncertainty in the calibration of the concentration in SIMS. A similar picture is seen with the sample annealed at 700 °C. The segregated peak has tightened up as seen in both MEIS and SIMS, and again SIMS probably overestimates the segregated peak concentration. However the substitutional fraction from 4 – 12 nm can be clearly seen. As concentration (at/cm 3 ) 4.0x10 21 3.5x10 21 3.0x10 21 2.5x10 21 2.0x10 21 1.5x10 21 1.0x10 21 5.0x10 20 0.0 a) 600°C 10s MEIS 600°C 10s SIMS 0 2 4 6 8 10 12 14 b) 2 4 6 8 10 12 14 Hall effect measurements were carried out on these samples, and the results are given in Figure 6.18. The sheet resistance was as low as 610 Ω/□ for the sample annealed at 650 °C for 10s. The 700 °C had a slightly higher Rs value of 684 Ω/□. It is suggested that this could be due to As clustering at the higher temperature. From these measurements the activated dose can be obtained and this was found to be in the region of 2.2E14 -2.4E14 cm -2 which is in reasonably good agreement with the values that could be obtained from the shoulder height in the SIMS comparison in Figure 6.17, which lends support to the validity of the comparisons. 149 650°C 10s MEIS 650°C 10s SIMS c) Depth (nm) Figure 6.17 MEIS and SIMS combined depth profiles. 700°C 10s MEIS 700°C 10s SIMS 2 4 6 8 10 12 14
R s (Ω/sq) 950 900 850 800 750 700 650 600 10s anneal sheet resistance actived dose 600 650 700 anneal temperature (C) 6.3.3 MEIS and XRD study of SPER on Cz and Epi 3 keV As – Comparison of the two techniques A set of samples using the same implant conditions as discussed with the previous section, i.e. 3 keV As + 2E15 cm -2 , were produced. Implants were carried out into both Cz and Epi Si wafers. Several different anneals were used to capture different stages of the SPER. The samples were studied with X-ray techniques (XRD, SR and GI- DXS), reported in more detail elsewhere (19). A comparison of the results from MEIS and XRD studies are presented in this section. Samples were implanted with 3 keV As ions, to a dose of 2E15 ions/cm 2 , into crystalline Cz and Epi Si wafers. Cz and Epi samples then underwent simultaneous anneals with temperatures and times of 550 °C: 200 s; 600 °C: 20 s; 650 °C: 10 s; and 700 °C: 10 s were chosen based on the requirements of the defect studies. 6.3.3.1 MEIS MEIS was carried out using 100 keV He + ions, with the samples aligned to the beam along the [īīı] channelling direction and the analyser positioned to collect data along the [ııı] blocking direction. The MEIS energy spectra of the as-implanted and 150 2.5x10 21 2.0x10 21 1.5x10 21 Figure 6.18 Sheet resistance and activated dose for 10 s annealing at different anneal temperatures. activated dose (at/cm 3 )
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R s (Ω/sq)<br />
950<br />
900<br />
850<br />
800<br />
750<br />
700<br />
650<br />
600<br />
10s anneal<br />
sheet resistance<br />
actived dose<br />
600 650 700<br />
anneal temperature (C)<br />
6.3.3 MEIS <strong>and</strong> XRD study <strong>of</strong> SPER on Cz <strong>and</strong> Epi 3 keV As – Comparison <strong>of</strong><br />
the two techniques<br />
A set <strong>of</strong> samples using the same implant condit<strong>ion</strong>s as discussed with the<br />
previous sect<strong>ion</strong>, i.e. 3 keV As + 2E15 cm -2 , were produced. Implants were carried out<br />
into both Cz <strong>and</strong> Epi Si wafers. Several different anneals were used to capture different<br />
stages <strong>of</strong> the SPER. The samples were studied with X-ray techniques (XRD, SR <strong>and</strong> GI-<br />
DXS), reported in more detail elsewhere (19). A comparison <strong>of</strong> the results from MEIS<br />
<strong>and</strong> XRD <strong>studies</strong> are presented in this sect<strong>ion</strong>.<br />
Samples were implanted with 3 keV As <strong>ion</strong>s, to a dose <strong>of</strong> 2E15 <strong>ion</strong>s/cm 2 , into<br />
crystalline Cz <strong>and</strong> Epi Si wafers. Cz <strong>and</strong> Epi samples then underwent simultaneous<br />
anneals with temperatures <strong>and</strong> times <strong>of</strong> 550 °C: 200 s; 600 °C: 20 s; 650 °C: 10 s; <strong>and</strong><br />
700 °C: 10 s were chosen based on the requirements <strong>of</strong> the defect <strong>studies</strong>.<br />
6.3.3.1 MEIS<br />
MEIS was carried out using 100 keV He + <strong>ion</strong>s, with the samples aligned to the<br />
beam along the [īīı] channelling direct<strong>ion</strong> <strong>and</strong> the analyser posit<strong>ion</strong>ed to collect data<br />
along the [ııı] blocking direct<strong>ion</strong>. The MEIS <strong>energy</strong> spectra <strong>of</strong> the as-implanted <strong>and</strong><br />
150<br />
2.5x10 21<br />
2.0x10 21<br />
1.5x10 21<br />
Figure 6.18 Sheet resistance <strong>and</strong> activated dose for 10 s <strong>annealing</strong> at different anneal<br />
temperatures.<br />
activated dose (at/cm 3 )
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