A domestic research team has discovered an error in the international standard used to determine defects in power semiconductors.

A Korean research team has revealed that an international evaluation index used to detect defects in 'SiC (Silicon Carbide)' power semiconductors—core components for electric vehicles and renewable energy facilities—contained errors, correcting the standard for the first time in about 15 years while proposing a new index.

The Korea Electrotechnology Research Institute (KERI) announced on the 25th that Dr. Moon-kyung Na, a principal researcher at the Next-Generation Semiconductor Research Center, along with a joint research team including Prof. Soon-gu Hong's team from Chungnam National University, Horiba STEC Korea, and SK siltron, successfully identified the true emission wavelength (characteristic luminescence wavelength) of internal defects in SiC semiconductors, which had been mistakenly known worldwide for about 15 years. The research results were published in the September 8 issue of the international journal Acta Materialia.

SiC power semiconductors are components that control current direction and power conversion while withstanding harsh environments of high temperatures and high pressures. They are widely used in advanced industries that must endure high voltages and heat, such as electric vehicles and renewable energy facilities.

During the semiconductor manufacturing process, if 'Stacking Faults' occur—where atoms pile up layer by layer but become minutely misaligned—the power semiconductor cannot perform at its full potential, making meticulous quality control essential.

In the industry, 'Photoluminescence (PL) inspection,' which tests semiconductors by shooting light, is utilized to find defects without breaking the semiconductor wafer. This method leverages the fact that the wavelength of light emitted from a defective area differs from that emitted from a defect-free area.

Analyzing over 100,000 defect data points contained in 207 commercial wafers, the research team revealed that 'Frank-type stacking faults' are the primary type of defect. Frank-type stacking faults occur when a single layer of atoms is missing or newly inserted within the crystal structure of the semiconductor—much like a cake layered with sheets and cream, where an extra layer of cream is added instead of the sheet.

Among Frank-type stacking faults, the '(4,1) Frank-type stacking fault' was known to emit 424-nanometer (nm, 1nm = 1 billionth of a meter) light, a standard reflected in the International Electrotechnical Commission (IEC) standards for 15 years. This standard had not been derived by meticulously comparing light signals with actual atomic structures on a 1-to-1 basis.

The research team located the defects using light and then precisely cut those exact locations in units of nanometers to directly verify them using atomic-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF HR-STEM). The results revealed that the actual indicator for the (4,1) Frank-type stacking fault is 459nm, not 424nm.

This achievement has a significant industrial impact as it dramatically improves the accuracy of quality inspection for invisible semiconductor materials. By accurately tracing the causes of defects to improve manufacturing processes, it can ultimately substantially enhance the quality and safety of electric vehicles and power conversion systems.

"This holds great significance in correcting long-standing global evaluation standards by directly connecting light signals with actual atomic structures without a single error," said Principal Researcher Na.

[ⓒ Global Economic Times. 무단전재-재배포 금지]