Rapid Diffusion of Molybdenum Trace Contamination in Silicon

1984 ◽  
Vol 36 ◽  
Author(s):  
S. P. Tobin ◽  
A. C. Greenwald ◽  
R. G. Wolfson ◽  
D. L. Meier ◽  
P. J. Drevinsky
Keyword(s):  
Diffusion Coefficient ◽  
Transition Metals ◽  
Lower Limit ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Deep Level ◽  
Depth Profiling ◽  
Epitaxial Layers ◽  
Epitaxial Silicon ◽  
Rapid Diffusion

ABSTRACTMolybdenum contamination has been detected in silicon epitaxial layers and substrate wafers after processing in any one of several epitaxial silicon reactors. Greatly reduced minority carrier diffusion lengths and lifetimes are consistent with Mo concentrations measured by DLTS in the 1012 and 1013 cm−3 ranges. Depth profiling of diffusion length and the Mo deep level show much greater penetration than expected from previous reports of Mo as a slow diffuser. The data indicate a lower limit of 10−8 cm2/sec for the diffusion coefficient of Mo in silicon at 1200°C, consistent with high diffusivities measured for other transition metals.

Evaluation of On-State Resistance and Boron-Related Levels in n-Type 4H-SiC

2005 ◽  
Vol 483-485 ◽  
pp. 425-428 ◽  
Author(s):  
R.R Ciechonski ◽  
Samuele Porro ◽  
Mikael Syväjärvi ◽  
Rositza Yakimova
Keyword(s):  
Minority Carrier ◽  
Deep Level ◽  
Schottky Diodes ◽  
Depth Profiling ◽  
Thermionic Emission ◽  
Barrier Heights ◽  
Transient Spectroscopy ◽  
State Resistance ◽  
Thick Layers

Specific on-resistance Ron estimated from current density-voltage characteristics of Schottky diodes on thick layers exhibits variations from tens of mW.cm2 to tens of W.cm2 for different doping levels. In order to understand the occurrence of high on-state resistance, Schottky barrier heights were first estimated for both forward and reverse bias with the application of thermionic emission theory and were in agreement with a literature reported values. Decrease in mobility with the temperature was observed and its dependencies of T–1.3 and T–2.0 for moderately doped and low doped samples respectively were estimated. From deep level measurements by Minority Carrier Transient Spectroscopy, an influence of shallow boron related levels and D-center on dependence of on-state resistance was observed, being more pronounced in low doped samples. Similar tendency was observed in depth profiling of Ron. This suggests a major role of boron in a compensation mechanism thus resulting in high Ron.

Measuring Diffusion Lengths in Epitaxial Silicon by Surface Photovoltage

1995 ◽  
Vol 386 ◽  
Author(s):  
John Lowell ◽  
Valerie Wenner ◽  
Damon Debusk
Keyword(s):  
Transition Metals ◽  
Optical Filters ◽  
Surface Photovoltage ◽  
Epitaxial Layers ◽  
Device Performance ◽  
Optical Surface ◽  
Epitaxial Silicon ◽  
Type Silicon ◽  
P Type ◽  
And Diffusion

ABSTRACTIn CMOS, the use of epitaxial layers for prevention of latch-up in logic technologies is well-known and pervasive. One of the crucial parameters is the amount of metallic contamination due to transition metals such as Fe in the epi since this phenomena effects both device performance and quality. However, the ability to measure this parameter on product material is not generally available due to inherent problems with most known methods. The limitation of traditional surface photovoltage is that the deep optical penetration of over a hundred microns is well-beyond the depth of most epitaxial layers and does not accurately profile the epitaxial region [1]. In this paper we report on the application of optical surface photovoltage (SPV) using a set of ultra-shallow optical filters to both quantify and qualify as-grown epitaxial layers on CZ P-type silicon. We believe that a non-contact, SPV measurement of Fe concentration and diffusion lengths within an epitaxial region has not been previously reported.

Understanding The Role Of Defects In Limiting The Minority Carrier Lifetime In Sic

1997 ◽  
Vol 483 ◽  
Author(s):  
W. A. Doolittle ◽  
A. Rohatgi ◽  
R. Ahrenkiel ◽  
D. Levi ◽  
G. Augustine ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electrical Activity ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Deep Level ◽  
Minority Carrier Lifetime ◽  
Injection Level ◽  
Growth Step ◽  
Sem Image

AbstractDeep level Transient Spectroscopy (DLTS), Electron Beam Induced Current (EBIC), EBIC Diffusion Length Mapping (EBIC-DLM) and contactless Photoconductive Decay (PCD) were used to characterize both bulk substrates and epitaxially grown Silicon Carbide films. Traps as deep as 0.93 eV were observed via DLTS. These traps may play a role in the persistent photoconductivity effect. EBIC reveals the electrical activity of the well known triangular defects. However, only some of these defects display electrical activity consistent with that of 3C-SiC inclusions, others do not. Additionally, not all defects identified in the EBIC images are observable in the topographic SEM image, possibly indicating a new, yet unidentified defect. EBIC revealed the electrical activity of defects including micro-pipes, dislocations (or possibly growth step edge decoration), surface polish damage, and bulk defects. Diffusion length maps of SiC indicate wide variations in diffusion length on both microscopic and macroscopic scales. EBIC-DLMindicatedepitaxial 4H SiC resulted in diffusion lengths from 0.1 to 3 μm, while bulk values were less than 0.07 μm. PCD measurements indicate tens of nanosecond to microsecond variations in lifetime. Lifetime verses injection level variations are observed and explained on the basis of trap energy. The injection level dependence of lifetime was observed at various nitrogen doping concentrations. Finally, electron beam annealing is found to dramatically improve the minority carrier lifetime in epitaxial SiC.

Gettering of FE By Aluminum In P-Type Cz Silicon

1996 ◽  
Vol 442 ◽  
Author(s):  
S. H. Ahn ◽  
S. Zhao ◽  
A. L. Smith ◽  
L. L. Chalfoun ◽  
M. Platero ◽  
...  
Keyword(s):  
Minority Carrier ◽  
Diffusion Length ◽  
Deep Level ◽  
Early Stage ◽  
Iron Silicide ◽  
Solubility Limit ◽  
Solar Cell Performance ◽  
Minority Carrier Diffusion Length ◽  
Carrier Diffusion ◽  
P Type

AbstractIn this study, we investigate the gettering process of Fe in p-type Cz silicon after iron has been introduced at the solubility limit at 1000°C. Deep Level Transient Spectroscopy (DLTS) was used to measure [FeB], a fingerprint of [Fei], at the center of samples. The minority carrier diffusion length and lifetime were calculated from Electron Beam Induced Current (EBIC) measurements. The fact that [FeB] is proportional to the negative second power of the minority carrier diffusion length at the high [FeB] regime confirms that FeB donors are the dominant recombination centers limiting solar cell performance with high Fe contamination. By quenching after heat treatment, we can maintain and measure the kinetics and thermodynamics of gettering exclusively. The getter/silicon interface was studied by comparison of the gettering rates of molten Al at 620°C, 700°C, and 800°C, and iron silicide at 700°C. We model Fe gettering with respect to temperature, time, solubility and precipitate nuclei density. In the early stage of Fe gettering, the process is dominated by precipitate formation around oxygen precipitate nuclei. The precipitate density is estimated to be on the order of 5×108cm−3. In later stages, Fe outdiffusion contributes to the [Fei] reduction. The early stage precipitation limits [Fei] reduction after short time to the solubility at the gettering temperature.

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