The Effects of Carbon on Czochralski Silicon Used for Dynamic Random Access Memory Production

1985 ◽  
Vol 59 ◽  
Author(s):  
R. A. Craven ◽  
W. E. Bailey ◽  
J. W. Moody ◽  
R. J. Falster ◽  
L. W. Shive
Keyword(s):  
Defect Density ◽  
Random Access ◽  
Relative Yield ◽  
Peak Performance ◽  
Interstitial Oxygen ◽  
Active Device ◽  
Recombination Lifetime ◽  
Czochralski Silicon ◽  
Oxygen Precipitation ◽  
Heterogeneous Processes

ABSTRACTCzochralski silicon with constant controlled oxygen level of 15+/-0.5 ppma (ASTM F121–80) and varying carbon content intentionally doped at five different levels from 0.1 ppma to 4.1 ppma (ASTM F123–81) was used to fabricate 16K dynamic random access memories, MOS test capacitors with guard rings, and pn junctions. The results of the experiment have been analyzed for relative yield to functional and refresh characteristics, MOS generation and bulk recombination lifetime, pn junction leakage, and both surface and bulk defect densities. Peak performance of the silicon did not occur at the lowest carbon level, but was dominated by the oxygen precipitate defect density and depth of the denuded zone near the active device regions. The results of the capacitor measurements, the DRAM yield measurements, the junction leakage measurements and the bulk and surface lifetime measurements are self-consistent and emphasize the need for control of the oxygen precipitation whether it is nucleated by carbon or other homogeneous and heterogeneous processes. There is no evidence that carbon has any impact on the device performance other than its impact on the precipitation kinetics of the interstitial oxygen.

Kinetic Model of Thermal Donor Evolution

1997 ◽  
Vol 469 ◽  
Author(s):  
K. F. Kelton ◽  
R. Falster
Keyword(s):  
Interstitial Oxygen ◽  
Oxygen Loss ◽  
Free Oxygen ◽  
Czochralski Silicon ◽  
Thermal Donor ◽  
Cluster Evolution ◽  
Oxygen Precipitation ◽  
High Diffusion Rate ◽  
Normal Diffusion ◽  
Small Clusters

ABSTRACTKinetic aspects of thermal donor (TD) formation in Czochralski silicon are shown to be consistent with the evolution of small oxygen clusters, as described within the classical theory of nucleation. Predictions for TD generation and interstitial oxygen loss are presented. Favorable agreement with experimental data requires that the rate constants describing cluster evolution be increased over those expected for a oliffusion-limited flux based on a normal diffusion coefficient for oxygen in silicon. This may signal an anomalously high diffusion rate for temperatures less than 500°C, as has been suggested by others. However, it may instead signal an enhanced concentration of free oxygen near clusters smaller than the critical size for nucleation. This is expected when the interfacial attachment rates become comparable with the rates at which oxygen atoms arrive in the vicinity of the sub-critical clusters. The link between thermal donor generation and oxygen precipitation processes demonstrated here provides a consistent framework for better understanding and controlling oxygen precipitation in silicon. Further, the kinetic TD generation and oxygen loss data provide a new window into the dynamical processes for small clusters, which underlie all nucleation phenomena.

First Principles Calculation for Point Defect Behavior, Oxygen Precipitation and Cu Gettering in Czochralski Silicon

2005 ◽  
Vol 108-109 ◽  
pp. 365-372 ◽  
Author(s):  
Koji Sueoka ◽  
S. Shiba ◽  
S. Fukutani
Keyword(s):  
Crystal Growth ◽  
Point Defect ◽  
First Principles ◽  
First Principles Calculation ◽  
Interstitial Oxygen ◽  
Defect Engineering ◽  
Czochralski Silicon ◽  
Oxygen Precipitation ◽  
Initial Stage ◽  
P Type

Theoretical consideration for technologically important phenomena in defect engineering of Czochralski silicon was performed with first principles calculation. (i) Point defect behaviour during crystal growth, (ii) enhanced oxygen precipitation in p/p+ epitaxial wafers, and (iii) Cu gettering by impurities are main topics in this work. Following results are obtained. (i) Interstitial Si I is dominant in p type Si while vacancy V is dominant in n type Si during crystal growth when dopant concentration is higher than about 1x1019atoms/cm3. (ii) In initial stage of oxygen precipitation including a few interstitial oxygen (O) atoms, BOn complex is more stable than On complex. The diffusion barrier of O atom in p+ Si is reduced to about 2.2eV compared with the barrier of about 2.5eV in intrinsic Si. (iii) In substitutional B, Sb, As, P and C atoms, only B atom can be an effective gettering center for Cu.

Oxygen Precipitation in Silicon: Numerical Models

1985 ◽  
Vol 59 ◽  
Author(s):  
J. P. Lavine ◽  
G. A. Hawkins ◽  
C. N. Anagnostopoulos ◽  
L. Rivaud
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Numerical Models ◽  
Local Concentration ◽  
Interstitial Oxygen ◽  
Czochralski Silicon ◽  
Oxygen Precipitation ◽  
Precipitate Growth ◽  
Evolution Of Precipitates ◽  
Precipitate Density

ABSTRACTWe present a numerical model that simulates the evolution of precipitates and the diffusion of interstitial oxygen in Czochralski silicon. The growth and/or dissolution of each precipitate and the local concentration of interstitial oxygen with which the precipitates interact are followed as a function of time. We treat realistic densities of discrete, interacting precipitates and determine how the precipitate density influences the extent of the precipitation. The model also treats oxygen outdiffusion and the formation of precipitate-free or denuded zones. We apply the model to previous experimental data on the time dependence of precipitate growth and to the development of denuded zones during intrinsic gettering.

Structure of Thermally-Induced Microdefects in Czochralski Silicon

1983 ◽  
Vol 31 ◽  
Author(s):  
F. A. Ponce ◽  
S. Hahn
Keyword(s):  
Quasi Equilibrium ◽  
Interstitial Oxygen ◽  
Thermally Induced ◽  
Czochralski Silicon ◽  
Oxygen Precipitation ◽  
Transmission Electron ◽  
Long Time ◽  
History Of ◽  
Silicon Materials ◽  
Oxygen Precipitates

ABSTRACTThe process of oxygen precipitation in Czochralski silicon materials has been studied using high resolution transmission electron microscopy. The resulting structure depends strongly on the thermal history of the material. The initial stages of precipitation involve the formation of clusters exhibiting strain fields which are coherent and isotropic at intermediate temperatures (∼7000°C). Incoherent defects are formed when the interstitial oxygen precipitates into substitutional sites in the silicon lattice. For long-time anneals, the quasi-equilibrium defect structure ranges from needle-like coesite (450–600°C), silica platelets (600–1000°C) to polyhedral silica precipitates (900–1200°C).

Rate Equation Modeling, Ab Initio Calculation, and High Sensitive FTIR Investigations of the Early Stages of Oxide Precipitation in Vacancy-Rich CZ Silicon

2009 ◽  
Vol 156-158 ◽  
pp. 211-216 ◽  
Author(s):  
G. Kissinger ◽  
J. Dabrowski ◽  
V.D. Akhmetov ◽  
Andreas Sattler ◽  
D. Kot ◽  
...  
Keyword(s):  
Ab Initio ◽  
Rate Equation ◽  
Ab Initio Calculation ◽  
Equation Modeling ◽  
Interstitial Oxygen ◽  
Czochralski Silicon ◽  
Early Stages ◽  
Highly Sensitive ◽  
Defect Species ◽  
Ftir Investigation

The results of highly sensitive FTIR investigation, ab initio calculations and rate equation modeling of the early stages of oxide precipitation are compared. The attachment of interstitial oxygen to VOn is energetically more favorable than the attachment to On for n  6. For higher n the energy gain is comparable. The point defect species which were detected by highly sensitive FTIR in high oxygen Czochralski silicon wafers are O1, O2, O3, and VO4. Rate equation modeling for I, V, On and VOn with n = (1..4) also yields O1, O2, O3 to appear with decreasing concentration and VO4 as that one of the VOn species which would appear in the highest concentration after RTA.

Oxygen Precipitation in Conventional and Nitrogen Co-Doped Heavily Arsenic-Doped Czochralski Silicon Crystals: Oswald Ripening

2009 ◽  
Vol 156-158 ◽  
pp. 275-278
Author(s):  
Xiang Yang Ma ◽  
Yan Feng ◽  
Yu Heng Zeng ◽  
De Ren Yang
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Czochralski Silicon ◽  
Silicon Crystals ◽  
Oxygen Precipitation ◽  
High Temperature Anneal ◽  
Oxygen Precipitates ◽  
Co Doped ◽  
Oswald Ripening

Oxygen precipitation (OP) behaviors in conventional and nitrogen co-doped heavily arsenic-doped Czocharalski silicon crystals subjected to low-high two-step anneals of 650 oC/8 h + 1000 oC/4-256 h have been comparatively investigated. Due to the nitrogen enhanced nucleation of OP during the low temperature anneal, much higher density of oxygen precipitates generated in the nitrogen co-doped specimens. With the extension of high temperature anneal, Oswald ripening of OP in the nitrogen co-doped specimens preceded that in the conventional ones. Moreover, due to the Oswald ripening effect, the oxygen precipitates in the conventional specimens became larger with a wider range of sizes. While, the sizes of oxygen precipitates in the nitrogen co-doped specimens distributed in a much narrower range with respect to the conventional ones.

Oxygen Precipitation in Heavily Phosphorus-doped Czochralski Silicon

2019 ◽  
Vol 18 (1) ◽  
pp. 1001-1011 ◽  
Author(s):  
Yuheng Zeng ◽  
Deren Yang ◽  
Xiangyang Ma ◽  
Xinpeng Zhang ◽  
Lixia Lin ◽  
...  
Keyword(s):  
Czochralski Silicon ◽  
Oxygen Precipitation ◽  
Phosphorus Doped

Enhancement of oxygen precipitation in quenched Czochralski silicon crystals

1989 ◽  
Vol 66 (8) ◽  
pp. 3958-3960 ◽  
Author(s):  
Akito Hara ◽  
Tetsuo Fukuda ◽  
Toru Miyabo ◽  
Iesada Hirai
Keyword(s):  
Czochralski Silicon ◽  
Silicon Crystals ◽  
Oxygen Precipitation

Gettering Processes for Sub-Micron VLSI

1986 ◽  
Vol 76 ◽  
Author(s):  
John Andrews
Keyword(s):  
Defect Density ◽  
Back Surface ◽  
Dislocation Network ◽  
Published Data ◽  
Interstitial Oxygen ◽  
Supersaturation Ratio ◽  
Zone Formation ◽  
Wide Range ◽  
Dry Oxidation ◽  
P Diffusion

ABSTRACTGettering by the dislocation network caused by P-diffusion into the back surface of Si wafers at 950° C for 1 hr. is often used for VLSI. However, transistors with sub-micron gates are jeopardized at 950°C because of possible source-drain punch through by lateral P-diffusion. The temperature dependence of gettering by P-diffusion has been investigated at 950, 900, and 850°C. Gettering by P-diffusion was found to be marginal at 900°C and totally ineffective at 850°C.Recently published data on the solubility and diffusivity of interstitial oxygen in Czochralski-grown Si has been used to develop a simple out-diffusion model for denuded zone formation during thermal oxidation. Comparison with experimental observations on samples with high interstitial SiO2 concentration [Oi]0, exposed to dry oxidation at 1100° C for various times up to 8 hrs. and followed by 24 hr. anneals in N2 at 700°C and 1050°C, reveal that SiO2 precipitation occurs when the supersaturation ratio exceeds 4.7. The model implies an optimum denuding temperature near 100° C for a dry oxidation time of 4 hrs. The bulk defect density was also observed to decrease more than a factor of 5 as the denuding time was increased from 0 to 8 hrs.Intrinsic gettering by SiO2 precipitates in Czochralski-grown silicon has been evaluated over a wide range of initial interstitial oxygen concentrations 15 < [Oi]0 < 22 ppma with and without a HI-LO-HI pre-process annealing cycle. Among samples of approximately 100 p-n junctions per wafer, reductions of 1–3 orders of magnitude in reverse leakage at 5 volts were achieved in the worst 10% of 500 μm square devices on wafers that were exposed to the HI-LO-HI heat treatment. Intrinsic gettering is most effective when [Oi]0 22 ppma, but leakage reduction among the worst diodes is achieved at the expense of a 2 or 3-fold increase in median leakage.

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