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The second issue New Specialty Chemical Products Development Department Initiatives for semiconductor process materials Wish to support initiatives for semiconductor process materials with an eye to the development of semiconductor LSI for which miniaturization and performance improvement continue. Tsutomu Watahiki Assistant Manager, New Specialty Chemical Products Development Department, Research & Development Operations ll, Laboratory and Specialty Products Development Department

To keep the surface of the circuit dust-free

The manufacturing of semiconductor LSI currently involves about 1,000 processes. What poses a challenge here is the various foreign matters that are left on the surface of the silicon wafers, such as shavings when the circuits are etched and chemical remnants from each process. Trouble may arise in circuits if such foreign matters remain on the surface, the key to raising yield in LSI manufacturing depends on how neatly the foreign matters can be removed. We, the semiconductor process material team, develop “detergents” which are chemicals for removing such foreign matters.

Inspection of the surface of silicon wafers with a microscope. Even a tiny dust particle cannot remain on the surface.
Inspection of the surface of silicon wafers with a microscope. Even a tiny dust particle cannot remain on the surface.

Basic research and market research cultivated over the years are our strength

Detergents are usually developed upon requests from customers regarding their specific requirements. Since the foreign matter which adheres to the surface varies depending on the manufacturing process, it is necessary to make detergents that remove specific foreign matters. It is essential to know what kind of foreign matter adheres and how it becomes adhered. However, such information is usually not disclosed because the LSI manufacturing process includes the manufacturer’s intellectual property. As such, we gather information by building connections with semiconductor equipment manufacturers and components and materials manufacturers and examine industry trends in conjunction with the in-house marketing division in making a hypothesis of the manufacturing process. Our task is to estimate the foreign matter that would adhere to the semiconductor wafer and clarify the foreign matter to be removed based on that hypothesis and to develop effective chemicals that remove such foreign matter.
In addition, since semiconductors are destined to improve performance, the materials and processes used undergo frequent change. Along with such change, detergents too are required to have new functions. We therefore are constantly required to come up with ideas to cope with the speed of change. The development of detergents that meet requirements in a short period calls for the daily accumulation of experimental data. Development team members were able to develop advanced skills through trial and error of methods to evaluate the performance of the detergents developed. As a result, we have become an elite team that supports leading-edge semiconductor companies.

“We would like to contribute to the improvement of performance of LSI through the development of detergents.”
“We would like to contribute to the improvement of performance of LSI through the development of detergents.”

Develop a detergent that is gentler than washing away with water

In 2014, we launched a neutral detergent as a product based on a new concept. While the acidic and alkaline chemicals, which had been the mainstream, have outstanding washing performance, they were highly corrosive. In leading-edge LSIs where the wiring pattern has become miniaturized to less than several tens of nanometers, the problem is with wire corrosion. To deal with this problem, the development team started the development of neutral detergents with low corrosiveness. Through the development of detergents with outstanding cleaning power and lower corrosiveness than water, we play a role in the miniaturization of LSI.
Although it has been said that the miniaturization of LSI is close to reaching its limit, new technologies have emerged every time, leading to progress. Various attempts are currently being made and we believe that our mission is to quickly identify the trends of such attempts and to develop detergents that can proactively solve problems, we are engaged in this research every day.

Example of washing using neutral detergent (left). Compared with conventional detergent (right), it can effectively remove particles on the surface.

Example of washing using neutral detergent (left). Compared with conventional detergent (right), it can effectively remove particles on the surface.