Research Highlights

Pattern Transfer of Both Sides of a Thin Film for Lithographical Processing

2021-12-20 39

[POSTECH research team led by Professor Seok Kim develops a pattern transfer method that allows the usage of both sides of a thin film for standard lithographical processing, which can significantly improve semiconductor performance.]

Hwang’s Law states that the capacity of semiconductor memory doubles every year and the Moore’s Law states that the performance of semiconductor-integrated circuits doubles every two years. In recent years, however, enhancing the performance of semiconductors has been difficult due to limitations in technology development. To this, a Korean research team has presented a method that can make both sides of a high-purity thin film into semiconductor devices. Using this method can drastically improve their performance.

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A research team led by Professor Seok Kim of the Department of Mechanical Engineering at POSTECH – in joint research with University of Illinois Urbana-Champaign and University of Virginia – has developed a self-delamination-based pattern transfer method that can place a high-purity silicon (Si) thin film*1 onto a substrate.

As the result of combining the thin film and the substrate in a well-controlled liquid environment, the thin film that is strongly attached to the substrate in the dry state can be self-delaminated from the substrate in the liquid solution.

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The researchers transferred the thin film facing up on the target substrate, put it in the liquid media after semiconductor processing, and flipped the self-delaminated thin film over. By taking the flipped thin film out of the solution and transferring it back to the substrate with the back side facing up, the semiconductor processing could be performed on both sides.

Applying the findings from this study allows semiconductor processing to be performed not only on silicon but also on surfaces of other high-purity semiconductor materials such as GaN (gallium nitride) and gallium arsenide (GaAs), so that the devices with more diverse performance can be fabricated.

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In addition, this technology can be used to develop 3D integrated circuits. These are manufactured by converting 2D patterned Si films into a 3D structure and are more applicable in semiconductor devices*2 compared to a 2D integrated circuit on the same silicon wafer*3 area.

3D integrated circuits are attracting attention as a way to improve performance and lower manufacturing costs, but complex processing has hindered their development. This is because high-performance semiconductor devices, accurate and rapid transfer of devices, and standardized processes are all required to develop the 3D integrated circuits. Improving the performance of semiconductor devices with the new method developed in this study brings us a step closer to developing 3D integrated circuits.

“This new technology will be applicable in manufacturing high-performance 3D integrated circuits or micro LED displays in the future,” remarked Professor Seok Kim on the significance of the study.
Supported by the BK21 Project of Korea, the findings from this study were recently published in Nature Communications, a sister journal of Nature.

1. High-purity film
A thin film with a thickness of less than micrometers (μm) with high proportion of pure substances, which are the main components in the substance.

2. Semiconductor device
A material that makes up an electronic circuit made of a semiconductor material. A semiconductor material refers to a material that makes a semiconductor device.

3. Silicon wafer
A thin silicon plate that forms the basis of integrated circuits.