Latest advances in high voltage, drift free, 4H-SiC PiN diodes

The multi-zone junction termination extension (MJTE) is a widely used edge termination technique for achieving high voltage SiC devices. It is commonly implemented with multiple lithography and implantation events. In order to reduce process complexity, cycle time, and cost, a single photolithography and single implant MJTE technique has been successfully developed. The method utilizes a pattern of finely graduated oxide windows that filter the implant dose and create a graded MJTE in a single implant and single photolithography step. Based on this technique, 6 kV / 0.09 cm2 PiN diodes were fabricated utilizing a 120-zone single-implant JTE design. This novel single-implant MJTE design captures 93% of the ideal breakdown voltage and has comparable performance and yield to a baseline three implant process.

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A Case for High Temperature, High Voltage SiC Bipolar Devices

Materials Science Forum ◽

10.4028/www.scientific.net/msf.556-557.687 ◽

2007 ◽

Vol 556-557 ◽

pp. 687-692 ◽

Cited By ~ 13

Author(s):

Anant K. Agarwal

Keyword(s):

High Temperature ◽

High Voltage ◽

Low Voltage ◽

Schottky Diodes ◽

Life Time ◽

Extreme Environment ◽

Junction Temperature ◽

Current Gain ◽

Pin Diodes ◽

Bipolar Devices

The last three years have seen a rapid growth of 600 V and 1200 V SiC Schottky diodes primarily in the Power Factor Correction (PFC) circuits. The next logical step is introduction of a SiC MOSFET to not only further improve the power density and efficiency of the PFC circuits but also to enable the entry of all SiC power modules in Pulse Width Modulated (PWM) based power converters such as motor control in 600-1200 V range. The combination of SiC MOSFET and Schottky diodes will offer 60-80% lower losses in most low voltage applications at normal operating temperatures (< 200°C) where no significant improvements in packaging are required. This will cover most commercial applications with the exception of those having to function under extreme environment (>200°C) such as applications in automotive, aerospace and oil/gas exploration. For these high temperature applications, a case can be made for 600 - 2000 V Bipolar Junction Transistors (BJTs) and PiN diodes provided we do our homework on high temperature packaging. A number of interesting device related problems persist in bipolar devices such as forward voltage increase in PiN diodes and current gain degradation in BJTs. For very high voltage (>10 kV) applications such as those found in utilities (Transmission and Distribution), Large Drives and Traction, a case can be made for >10 kV PiN diodes, IGBTs, Thyristors and GTOs. While IGBTs will be restricted to <200°C junction temperature, the PiN diodes, Thyristors and GTOs may be operated at >250°C junction temperature provided that the high temperature, high voltage packaging issues are also addressed. Significant progress has been made in the development of the p-channel IGBTs and GTOs. The main issues seem to be the VF degradation due to stacking fault formation and improvement of minority carrier life-time.

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Study of Forward Voltage Drift in Diffused SiC PiN Diodes Doped by Al or B

Materials Science Forum ◽

10.4028/www.scientific.net/msf.483-485.989 ◽

2005 ◽

Vol 483-485 ◽

pp. 989-992 ◽

Cited By ~ 1

Author(s):

S.I. Maximenko ◽

Stanislav I. Soloviev ◽

A.E. Grekov ◽

A.V. Bolotnikov ◽

Ying Gao ◽

...

Keyword(s):

Current Density ◽

Room Temperature ◽

Stacking Faults ◽

Applied Current ◽

Forward Voltage ◽

Pin Diodes ◽

Applied Current Density ◽

Voltage Drift ◽

Significant Change ◽

Degradation Testing

The degradation of diffused SiC PIN diodes during forward-biased operation was studied by first fabricating PIN diodes by diffusion of aluminum or boron into 4H-SiC substrates with n-type 10-15 µm thick epilayers doped by nitrogen up to 5x1015cm-3. The formed diodes were subjected to degradation testing under an applied current density of 200A/cm2 at room temperature. The majority of the Al diffused diodes demonstrated a voltage drift, ΔVf, of more than 2 V, while B-doped diodes showed no significant change in forward voltage. The EBIC mode of SEM was employed to monitor nucleation and expansion of stacking faults.

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13-kV, 20-A 4H-SiC PiN Diodes for Power System Applications

Materials Science Forum ◽

10.4028/www.scientific.net/msf.778-780.855 ◽

2014 ◽

Vol 778-780 ◽

pp. 855-858 ◽

Cited By ~ 4

Author(s):

Dai Okamoto ◽

Yasunori Tanaka ◽

Tomonori Mizushima ◽

Mitsuru Yoshikawa ◽

Hiroyuki Fujisawa ◽

...

Keyword(s):

Power System ◽

High Voltage ◽

Light Emission ◽

Voltage Drop ◽

High Current ◽

Forward Voltage ◽

Pin Diodes ◽

Current Switching ◽

Forward Voltage Drop

We successfully fabricated 13-kV, 20-A, 8 mm × 8 mm, drift-free 4H-SiC PiN diodes. The fabricated diodes exhibited breakdown voltages that exceeded 13 kV, a forward voltage drop of 4.9–5.3 V, and an on-resistance (RonAactive) of 12 mW·cm2. The blocking yield at 10 kV on a 3-in wafer exceeded 90%. We investigated failed devices using Candela defect maps and light-emission images and found that a few devices failed because of large defects on the chip. We also demonstrated that the fabricated diodes can be used in conducting high-voltage and high-current switching tests.

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