The solubility of carbon in silicon has been measured over the temperature range 1560 to 2900°C. The enthalpy of solution is 59±3 kcal/mole. A phase diagram for the system Si–C is presented, embodying these solubility data as well as the results of other high-temperature experiments with silicon carbide. It is found that SiC possesses a peritectic point at 2830±40°C. These studies were carried out in argon at pressures as high as 35 atmos. Solubilities of carbon in germanium were measured in the temperature range 2780 to 3170°C, at argon pressures up to 55 atmos, and a tentative phase diagram is given.
We report an international interlaboratory dual experiment to determine the calibration factor used to calculate the interstitial oxygen content of silicon from room‐temperature (300 K) infrared (IR) absorption measurements. We conducted round robins for both the infrared and the absolute measurements on the same or equivalent specimens. The calibration factor for computing the oxygen content of silicon in parts per million atomic (ppma) from a room‐temperature measurement of the absorption coefficient at 1107 cm−1 was determined to be
6.28±0.18 normalppma/cm−1
. The IR round robin showed a reproducibility on the order of 3%.
The methodology and experiment for certification of reference specimens for determining interstitial oxygen concentration in semiconductor silicon are reported. These reference specimens are intended for calibration of infrared spectrophotometers which measure the 1107 cm' oxygen peak in silicon to enable users to improve their measurement agreement. Based on an earlier international Grand Round Robin study, this measurement agreement is at best 5.4% (2cr).Industry requirements for measurement comparison are much more demanding, and a methodology to satisfy those requirements is described. The most important aspect of this methodology is to reduce interlaboratory variation by the use of a single infrared instrument for certification. The certification uncertainty depends primarily on the improved repeatability of this instrument. Other sources of uncertainty were nonuniformity in both oxygen concentration and thickness over the specimen area, and variations in residual oxygen among the float-zone specimens which provided zerooxygen reference for the reference sets. These various sources were combined in quadrature to arrive at 2cr estimates of uncertainty under 0.2% at three oxygen levels.
InfroductionThe methodology and experiment for the development of reference specimens for the measurement of interstitial oxygen concentration in silicon, which has long been of scientific interest and is important to manufacturers of silicon semiconductor devices, is described. The concentration of oxygen in silicon affects the formation of Si-O precipitates which serve as gettering sites for unwanted fastdiffusing impurities. It also affects, by a precipitationhardening mechanism, distortions of silicon wafers due to thermal treatments during integrated circuit manufacture.
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