Oxygen and Carbon Defect Characterization In Silicon by Sims
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OXYGEN AND CARBON DEFECT CHARACTERIZATION IN SILICON BY SIMS
R. S. HOCKETT, P. B. FRAUNDORF, D. A. REED, D. H. WAYNE, and G. K. FRAUNDORF* *Monsanto Electronic Materials Company, 800 North Lindbergh Blvd., St. Louis, MO 63167 **Charles Evans & Associates, 1670 South Amphlett Blvd., Suite 120, San Mateo, CA 94402 ABSTRACT Oxygen and carbon aggregation in silicon after thermal processing can be characterized using SIMS profiles and SIMS imaging. Fluctuations in the oxygen SIMS signal during the profile have been correlated with the change in interstitial oxygen after thermal processing as measured by FTIR and the precipitate size as measured by TEM. In cases where precipitation is known to be the cause of impurity clustering, a computer program for simulating the profiling process allows semi-quantitative characterization of precipitates as a function of depth. The use of a Resistive Anode Encoder on a CAMECA IMS-3f coupled with image enhancement can be used to image oxygen and carbon related defects. Examples of this technique are given by imaging oxygen aggregation and the co-aggregation of oxygen and carbon in thermally-processed Czochralski-silicon.
INTRODUCTION The diffusion and precipitation of oxygen in Czochralski(CZ)-silicon during integrated circuit processing can dramatically affect both the electrical and mechanical properties of these substrates and of the devices fabricated on them [1]. Secondary ion mass spectrometry (SIMS) has recently been used to characterize the diffusion and precipitation of oxygen in CZ-silicon after thermal processing [2-3]. Local fluctuations in the SIMS oxygen signal have been correlated with defects delineated by Wright etching [3], and Shimura, et al [3] reference unpublished TEM and SIMS work by P.B. Fraundorf and R.S. Hockett as showing a correlation between these SIMS oxygen fluctuations and oxygen precipitates. In order to better understand the relationship between these SIMS oxygen fluctuations and oxygen precipitates, a study was begun to correlate the SIMS data with FTIR data on precipitation and with TEM data on oxygen precipitates. SIMS imaging was included to determine whether the fluctuations were due to oxygen variations only between successive analyte volumes during the SIMS profile. The intention of this study is to evaluate the usefulness of SIMS for characterizing local oxygen precipitation. The power of this technique is then illustrated by characterizing carbon and oxygen co-aggregation in carbon-doped, thermally processed CZ-silicon. ANALYTICAL EQUIPMENT SIMS profiles were measured using a CAMECA IMS-3f Ion Microanalyzer, a cesium primary ion beam with an impact energy of 14.5 keV, and the detection of secondary negative ions of oxygen and carbon.
Mat. Res. Soc. Symp. Proc. Vol. 59. 91986 Materials Research Society
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The primary beam current, raster area, and analysis area were varied depending upon the analysis purpose, as will be evident in the discussion. Secondary ion image acquisition is accomplished using a Resistive Anode Encoder [4] on a CA
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