Defect Formation Behaviors in Heavily Doped Czochralski Silicon

Abstract

To reveal a difference of defect formation behaviors, i.e. grown-in void formation during crystal growth and oxide precipitation in nand p-type silicon, we have investigated by using heavily boronand arsenic-doped silicon crystals. The density of void defects in heavily boron doped silicon was decreased with a shrinking OSFring, but in arsenic doped silicon were increased with resistivities below 3.3mΩcm. On the other hand, for oxygen precipitation, the nucleation rate in boron doped silicon was enhanced with increasing resistivities, while decreased by one tenth in reference to lightly doped silicon for resistivities up to 4.4mΩcm in arsenic doped silicon. These contrastive phenomena between n-and p-type cannot be explained with a growth model of precipitates by an accelerated diffusion of oxygen in silicon. We believed that the nucleation rate of oxide precipitates related to a dependence of point defects on fermi level closely.

Review—Properties of Intrinsic Point Defects in Si and Ge Assessed by Density Functional Theory

“…On the basis of the results calculated with DFT, an appropriate model of intrinsic point defect behavior in heavily doped Si is proposed in Effect of dopants in heavily doped Si crystals section. 22,68,71 The Voronkov model, while taking into account the present improvements, clearly explains all reported experimental results [120][121][122][123][124][125][126][127] on grown-in defects in heavily doped Si.…”

“…Figure 30 plots the calculated dependence of C V eq,tot (T m ) -C I eq,tot (T m ) on dopant type and concentration using the present model. It has been reported [121][122][123][124][125] that the OSF ring radius in p-type CZ-Si shrinks when the B concentration is higher than ∼1 × 10 18 B cm −3 and that the crystals becomes I-rich (the OSF ring disappearing in the crystal center) for B concentrations higher than ∼1 × 10 19 B cm −3 . The results in the present paper reveal that the value of C V eq,tot (T m ) -C I eq,tot (T m ) starts 22 to decrease at ∼1 × 10 18 B cm −3 and becomes negative at ∼2 × 10 19 B cm −3 in excellent quantitative agreement with the experiment.…”

Oxygen Precipitation in Highly Doped Silicon Substrates

“…Interestingly, the oxygen diffusivity was also studied by SIMS oxygen depth profiling after an out-diffusion treatment in the temperature range of 700 • C-1050 • C without finding any impact of the arsenic concentration on the oxygen diffusion constant. 26 This result would rule out a reduction in oxygen diffusivity as a reason for the reduced oxygen precipitation in heavily arsenic-doped silicon.…”

“…Before the ramped anneal, the samples were pre-annealed at 1150 • C for 2h and then kept at 650 • C for 1 h. The effectiveness of the permanence at 650 • C in promoting oxygen precipitation in arsenic doped samples is in agreement with other published results. 11,26 A very systematic investigation was published by Sugimura et al, 26 where the impact of three different arsenic concentrations: 1.7 × 10 15 at/cm 3 (lightly doped, 3 • cm), 1.7 × 10 18 at/cm 3 (18 m • cm) and 1.6 × 10 19 at/cm 3 (3.9 m • cm), on oxygen precipitation was studied. In their work, an increased arsenic concentration was found to cause a retardation in oxygen precipitation and a reduced precipitate density after a nucleation anneal (temperature: 600 • C -750 • C, Time: 1 -96 hours) applied after an epi dissolution treatment and followed by a growth anneal of 16 hours at 1000 • C. In this work, the oxygen concentration of the arsenic-doped samples was not reported, therefore it remains uncertain whether the observed differences in oxygen precipitation behavior are solely due the different arsenic concentration or partially also to a different oxygen concentration between the samples.…”

Computer Simulation of Concentration Distribution of Intrinsic Point Defect Valid for All Pulling Conditions in Large-Diameter Czochralski Si Crystal Growth

“…(ii) The ultra-heavy (> 5 × 10 19 cm −3 ) doping of B suppresses the interstitial cluster formation, and that of P or As suppresses the void formation. 3,29,30 However, the mechanism behind this suppression is still not clear. 4,30 Because the ultra-heavily doped Si is necessary, especially for power device applications, the mechanism should be clarified.…”