Selective electrochemical wafer thinning for silicon characterization
A new technique is reported for rapidly determining interstitial oxygen (O{sub i}) in heavily doped n{sup +} and p{sup +} silicon. This technique includes applying a selective electrochemical (SE) thinning process and infrared transmittance to measure the Si-O band on a limited area of a silicon wafer. Oxygen reference material was used to establish a Fourier Transform Infrared-selective ion mass spectrometry, (FTIR-SIMS) calibration curve for the thinned samples. Internally developed software offers the capability of using different algorithms for calculating O{sub i}. The O{sub i} concentrations in Czochralski (CZ) silicon with resistivities as low as 0.009 {Omega} cm were determined using the SE technique on bulk and thermally processed silicon. In contrast to mechanical thinning, localized SE area thinning maintains wafer integrity for additional material or device processing. Stress generated during the formation of thick PS layers can exceed the elastic limit of silcon and induce interfacial defects. We identified in n{sup +} silicon a stress-induced dislocation network at 45{degree} with a [010] direction for {l_brace}100{r_brace} silicon. Orthogonal dislocation networks observed in the [110] direction are identified in boron-doped silicon with concentrations of greater than 3 {times} l0{sup 17} atoms cm{sup {minus}3}. These dislocation networks show a tendency to agglomerate into bundles as the boron concentration increases. The Interfacial defects observed by optical microscopy did not interfer with O{sub i} detemination.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 10163253
- Report Number(s):
- SAND-91-2764; ON: DE93015083
- Resource Relation:
- Other Information: PBD: Mar 1993
- Country of Publication:
- United States
- Language:
- English
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