Control of grown-in defects and oxygen precipitates in silicon wafers with DZ-IG structure by ultrahigh-temperature rapid thermal oxidation

Abstract

A new control technique for achieving compatibility between crystal quality and gettering ability for heavy metal impurities was demonstrated for a nitrogen-doped Czochralski silicon wafer with a diameter of 300 mm via ultra-high temperature rapid thermal oxidation (UHT-RTO) processing. We have found that the DZ-IG structure with surface denuded zone and the wafer bulk with dense oxygen precipitates were formed by the control of vacancies in UHT-RTO process at temperature exceeding 1300 °C. It was also confirmed that most of the void defects were annihilated from the sub-surface of the wafer due to the interstitial Si atoms that were generated at the SiO2/Si interface. These results indicated that vacancies corresponded to dominant species, despite numerous interstitial silicon injections. We have explained these prominent features by the degree of super-saturation for the interstitial silicon due to oxidation and the precise thermal properties of the vacancy and interstitial silicon.

Point Defect Reaction in Silicon Wafers by Rapid Thermal Processing at More Than 1300°C Using an Oxidation Ambient

“…However, at the maximum temperature of 1350 • C, even in a 100% oxygen ambient, marked oxygen precipitation was observed at a density of order 10 9 cm −3 . This is caused by V remaining dominant in the wafers after RTP, even though I becomes supersaturated, as reported Araki et al 5,8 Next, we determined the degree of I supersaturation for RTP using an oxidation ambient. The values of C I and C V at the end point of the maximum temperature in RTP can be obtained analytically.…”

“…Furthermore, Maeda et al explained this feature as a characteristic state of point defects in the wafers using a numerical simulation. 8 That is, although I becomes supersaturated in wafers subjected to RTP using a pure oxygen ambient, the V concentration is higher than the I concentration when RTP is performed above 1300 • C. However, the residual V concentration in the wafers strongly depends on RTP conditions such as the heating temperature, ambient, and cooling rate. 2,6 Thus, precise models are needed to describe the point defect concentrations induced in the wafers by various RTP conditions.…”

Preferential Growth Mode of Large-Sized Vacancy Clusters in Silicon: A Neural-Network Potential and First-Principles Study

“…The Tersoff and EDIP potentials predict these atoms to move away from the V 5 cluster, as is observed for the monovacancy (Figure (d) and (e)). Accurate prediction of strain distribution around a V cluster, as well as E f , will be important to understand its structure-related properties, e.g., void shrinkage by the interaction with self-interstitials, growth of inner oxide walls, and mode change of void defects by nitrogen and carbon atoms . For such purposes, therefore, the ANN potential has a great advantage over conventional empirical potentials.…”

Trap‐Limited Vacancy Diffusion in Silicon at High Temperatures

“…The actual depleted width is remarkably shorter of about 60 μm, showing that the vacancy diffusivity, in a range from 1250 to 1050 °C, is essentially smaller than that predicted by Equation . The vacancy profiles of this type, with a similar width of vacancy‐depleted zones, are also manifested in the depth profiles of vacancy‐assisted oxygen precipitation in RTA wafers . 3) An enhanced self‐diffusivity induced by a hot proton irradiation in float‐zoned Si is limited by recombination of self‐interstitials (very fast species) with vacancies.…”