Performance limiting micropipe defects in silicon carbide wafers

Neudeck, Philip G.; Powell, J. A.

doi:10.1109/55.285372

Cited by 286 publications

(119 citation statements)

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“…The micropipe is well-documented as the most harmful defect to 4H-and 6H-SiC power device performance [6]. As discussed in References [7][8][9][10], micropipes are hollow-core screw dislocations with Burgers vectors ≥ 2c formed during the SiC sublimation wafer growth process.…”

Section: Introductionmentioning

confidence: 99%

“…Because of the non-terminating behavior of screw dislocations, both hollowcore and non-hollow-core screw dislocations and associated crystal lattice stresses are replicated in subsequently grown SiC epilayers [11,12]. Micropipe defects cause premature breakdown pointfailures in SiC high-field devices fabricated in 4H-and 6H-SiC c-axis crystals with and without epilayers [6]. To date the high density of micropipe defects has prevented the simultaneous realization of high-voltage SiC devices with sufficient areas to carry high on-state currents.…”

Section: Introductionmentioning

confidence: 99%

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Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P⁺N Junction Rectifiers

1997

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It is well-known that SiC wafer quality deficiencies are delaying the realization of outstandingly superior 4H-SiC power electronics. While efforts to date have centered on eradicating micropipes (i.e., hollow core super-screw dislocations with Burgers vector > 2c), 4H-SiC wafers and epilayers also contain elementary screw dislocations (i.e., Burgers vector = 1c with no hollow core) in densities on the order of thousands per cm 2 , nearly 100-fold micropipe densities. This paper describes an initial study into the impact of elementary screw dislocations on the reverse-bias current-voltage (I-V) characteristics of 4H-SiC p + n diodes. First, Synchrotron White Beam X-ray Topography (SWBXT) was employed to map the exact locations of elementary screw dislocations within small-area 4H-SiC p + n mesa diodes. Then the high-field reverse leakage and breakdown properties of these diodes were subsequently characterized on a probing station outfitted with a dark box and video camera. Most devices without screw dislocations exhibited excellent characteristics, with no detectable leakage current prior to breakdown, a sharp breakdown I-V knee, and no visible concentration of breakdown current. In contrast devices that contained at least one elementary screw dislocation exhibited a 5% to 35% reduction in breakdown voltage, a softer breakdown I-V knee, and visible microplasmas in which highly localized breakdown current was concentrated. The locations of observed breakdown microplasmas corresponded exactly to the locations of elementary screw dislocations identified by SWBXT mapping. While not as detrimental to SiC device performance as micropipes, the undesirable breakdown characteristics of elementary screw dislocations could nevertheless adversely affect the performance and reliability of 4H-SiC power devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P⁺N Junction Rectifiers

1997

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“…which lies somewhat below the theoretical calculation (2). Silicon experimental studies also indicate that pulse shape does not significantly change experimental device failure power densities, so that average power density may be used as a good approximation when diode voltage and/or current waveforrns are non-constant over the pulse duration [14].…”

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confidence: 96%

Non-Micropipe Dislocations in 4H-SiC Devices: Electrical Properties and Device Technology Implications

et al. 1998

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It is well-known that SiC wafer quality deficiencies are delaying the realization of outstandingly superior 4H-SiC power electronics. While efforts to date have centered on eradicating micropipes (i.e., hollow core super-screw dislocations with Burgers vectors > 2c), 4H-SiC wafers and epilayers also contain elementary screw dislocations (i.e., Burgers vector = lc with no hollow core) in densities on the order of thousands per cm 2, nearly 100-fold micropipe densities. While not nearly as detrimental to SiC device performance as micropipes, it has been previously shown that diodes containing elementary screw dislocations exhibit a 5% to 35% reduction in breakdown voltage, higher pre-breakdown reverse leakage current, softer reverse breakdown I-V knee, and concentrated microplasmic breakdown current filaments when measured under DC testing conditions. This paper details the impact of elementary screw dislocations on the experimentally observed reverse-breakdown pulse-failure characteristics of low-voltage (< 250 V) small-area (< 5 × 10-4 cm2) 4H-SiC p+n diodes. The presence of elementary screw dislocations did not significantly affect the failure properties of these diodes when subjected to non-adiabatic breakdown-bias pulsewidths ranging from 0.1 μs to 20 μs in duration. Diodes with and without elementary screw dislocations exhibited positive temperature coefficient of breakdown voltage and high junction failure power densities well above the failure power densities exhibited by highly reliable silicon power rectifiers. This preliminary result, based on measurements from one wafer of SiC diodes, suggests that highly reliable low-voltage SiC rectifiers may be attainable despite the presence of elementary screw dislocations.

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“…For example, the micropipes increase leakage current and reduce the breakdown voltage of SiC devices (Neudeck & Powell, 1994;Wahab et al, 2000). All the samples used in this section were 6H-SiC wafers grown by sublimation method.…”

Section: Characterizationsmentioning

confidence: 99%

Bulk Growth and Characterization of SiC Single Crystal

Ning¹

2011

Silicon Carbide - Materials, Processing and Applications in Electronic Devices

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Performance limiting micropipe defects in silicon carbide wafers

Cited by 286 publications

References 13 publications

Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P⁺N Junction Rectifiers

Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P⁺N Junction Rectifiers

Non-Micropipe Dislocations in 4H-SiC Devices: Electrical Properties and Device Technology Implications

Bulk Growth and Characterization of SiC Single Crystal

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Performance limiting micropipe defects in silicon carbide wafers

Cited by 286 publications

References 13 publications

Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P+N Junction Rectifiers

Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P+N Junction Rectifiers

Non-Micropipe Dislocations in 4H-SiC Devices: Electrical Properties and Device Technology Implications

Bulk Growth and Characterization of SiC Single Crystal

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Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P⁺N Junction Rectifiers

Breakdown Degradation Associated With Elementary Screw Dislocations In 4H-SiC P⁺N Junction Rectifiers