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Investigation on the Mechanisms of Nitrogen Shallow Implantation Influence on Trap Properties of SiO_2/n-Type 4H-SiC Interface

100%

Król K., Sochacki M., Szmidt J.

Acta Physica Polonica A

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2014

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vol. 125

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issue 4

1033-1037

EN

Silicon carbide (SiC) is the only wide-bandgap semiconductor capable of forming native dielectric layer of SiO_2 by thermal oxidation. This unique property of SiC combined with its high thermal conductivity and high critical field makes this semiconductor material suitable for high power electronic devices. Unfortunately, the state-of-the art technology does not use the full benefits of the material, especially in the case of MOSFET transistors. This is caused by insufficient electrical parameters of SiO_2/SiC interface. Two-component structure of the material and its high density result in high level of interface traps reducing the surface mobility and thus increasing series resistance of the device. One of the proposed methods of reducing the trap density in SiC MOS structure is a shallow nitrogen implantation prior to oxidation. This technique is based on the observation that introducing nitrogen into the SiO_2/SiC system results in significant reduction of trap states density and increase of the channel effective mobility. The shallow implantation technique has been reported to be as much effective as nitric oxide annealing which is one of the most effective techniques for oxide quality improvement in case of SiC. Unlike the diffusion based techniques, like postoxidation annealing, implantation of the nitrogen prior oxidation has the possibility of nitrogen concentration control near the oxide interface during oxidation process itself. This property is important since it was shown that the improvement degree is directly proportional to amount of nitrogen built in the vicinity of SiO_2/SiC interface during oxidation. However, previous investigations about this technique were inconclusive about the influence of implantation parameters and process conditions on observed effects. Both improvement and deterioration of interface quality was observed by different researchers. This behavior was never explained clearly. The primary objective of this research is to analyze the impact of implantation conditions on electrical properties of SiO_2/SiC MOS structure. This analysis is used to evaluate a hypothetical description of physical phenomena during oxidation of shallowly implanted substrates.

2

The Effect of Phosphorus Incorporation into SiO_2/4H-SiC (0001) Interface on Electrophysical Properties of MOS Structure

88%

Król K., Konarski P., Miśnik M., Sochacki M., Szmidt J.

Acta Physica Polonica A

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2014

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vol. 126

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issue 5

1100-1103

EN

This paper describes the influence of phosphorus incorporation into SiO_2/4H-SiC system. The main scope is an analysis of the slow responding trap states (near interface traps) since the influence of phosphorus technology on fast traps has already been investigated by numerous research groups. Two different phosphorus incorporation methods were incorporated - the diffusion-based process of POCl_3 annealing and ion implantation. We have shown that regardless of method used a new distinct near interface trap center can be found located approximately at E_{V} + 3.0 eV. This trap can be related to the incorporated phosphorus amount as shown through secondary ion mass spectroscopy measurements.

3

Depth Profile Analysis of Phosphorus Implanted SiC Structures

76%

Konarski P., Król K., Miśnik M., Sochacki M., Szmidt J., Turek M., Żuk J.

Acta Physica Polonica A

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2015

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vol. 128

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issue 5

864-866

EN

Secondary ion mass spectrometry depth profile analyses were performed on two sets of 4H-SiC(0001) substrate samples implanted with phosphorus. Both sets were processed under the same conditions. We implanted the samples with 100 keV (10¹¹-10¹⁴ cm¯²) phosphorus ions through the thin chemical vapor deposition deposited silicon dioxide stopping mask in order to obtain an ultra-shallow implantation profile. After phosphorus implantation, secondary ion mass spectrometry depth profile analysis was performed on the first set of samples and the second set was subjected to thermal oxidation procedure at 1200°C in order to create a dielectric layer. The aim of the oxidation process was formation of the silicon dioxide layer enriched with phosphorus: the element, which is considered to be suitable for trap density reduction. Ion implantation parameters as well as oxidation and chemical etching procedures were examined for the proper incorporation of phosphorus into the subsurface structure of the silicon oxide. Secondary ion mass spectrometry depth profile analysis was performed with Physical Electronics 06-350E sputter ion gun and QMA-410 Balzers quadrupole mass analyser. The analytical parameters such as: 1.7 keV Ar⁺ ion beam digitally scanned over 3×3 mm² area and ion erosion rate of 1.4 nm/min and sampling rate of 0.3 nm, were suitable for samples oxidized after ion implantation.

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3 Acta Physica Polonica A

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3 Szmidt J.

2 Konarski P.

2 Miśnik M.

1 Turek M.

1 Żuk J.

Investigation on the Mechanisms of Nitrogen Shallow Implantation Influence on Trap Properties of SiO_2/n-Type 4H-SiC Interface

The Effect of Phosphorus Incorporation into SiO_2/4H-SiC (0001) Interface on Electrophysical Properties of MOS Structure

Depth Profile Analysis of Phosphorus Implanted SiC Structures