Semiconductor Wafer Defect Inspection Without Cutting

KAIST Professor Lee Jeongcheol's Team Develops Non-Destructive Structural Analysis Equipment
Expecting Revolutionary Improvements in Wafer Defect Inspection Cost and Speed

Samsung Electronics' Advanced Institute of Technology has developed a new transistor structure using graphene, the "dream material." The photo shows a semiconductor wafer made using graphene transistors.

[Asia Economy Reporter Kim Bong-su] Domestic researchers have developed an analytical device that can measure the thickness of semiconductor wafers without cutting them.

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 19th that Professor Jeongcheol Lee's research team from the Department of Mechanical Engineering developed a wafer non-destructive analysis device that can inspect silicon thin film-cavity structures using the interference effect of near-infrared light.

Thin film-cavity structures with thicknesses on the order of 1 micrometer (μm) are used in various microelectromechanical systems (MEMS) devices such as pressure sensors, micromirrors, and transceivers. In these MEMS devices, the thickness of the thin film and the height of the cavity are key design parameters for device performance, so measuring the thickness of the fabricated structure is essential for analyzing device behavior. However, until recently, despite the disadvantage that the wafer cannot be used in subsequent processes, cross-sectional imaging techniques that cut the wafer and measure thickness with high-resolution microscopes such as scanning electron microscopes have been used.

Conceptual diagram of near-infrared based wafer nondestructive analysis equipment and inspection results of single-layer thin film-cavity structure. Image provided by KAIST

To non-destructively measure the thickness of silicon thin film-cavity structures on the order of 1 μm, the research team developed a near-infrared interference microscope. Considering the optical properties of silicon and the interference length of light, the team designed and built near-infrared measurement equipment. The developed near-infrared interference microscope measured single-layer thin film-cavity structures of 1 μm and sub-1 μm thickness with deviations less than 100 nanometers (nm). They also proposed a method to identify virtual interfaces caused by multiple reflections and successfully demonstrated thickness measurement of hidden silicon thin films in multilayer silicon thin film-cavity structures.

This research was published online on July 14 in the international journal Advanced Engineering Materials and was selected as the back cover paper for the October issue.

The research team confirmed that the method can be applied not only to silicon thin film-cavity structures but also to functional wafers such as Silicon-on-Insulator (SOI) wafers by successfully measuring the thickness of silicon and the hidden oxide layer inside. They also stated that by selecting appropriate wavelengths, the technique can be applied to non-destructive inspection of other semiconductor materials such as germanium. This study proposing a non-destructive inspection method for semiconductor substrates is expected to be applied to real-time non-destructive inspection for identifying device defects during semiconductor processing.

Professor Jeongcheol Lee, who led the research, said, "The developed technology differs from existing methods in that it measures the internal structure of semiconductor materials non-destructively using widely used infrared light sources," adding, "Due to its safety and precision advantages, it will improve the inspection speed of semiconductor materials and devices, contributing to the semiconductor-related industry and the advancement of our lives."

This content was produced with the assistance of AI translation services.