Spain's Wooptix Deploys Metrology Tool at Korean Chipmaker

A tool that measures how much a wafer warps during processing and how even its surface is has arrived inside a Korean chipmaker's fab. Spanish startup Wooptix, which makes the metrology equipment, has recently installed a research (Lab) system at a Korean chipmaker and begun technology validation and collaboration. The partner company and the scope of the cooperation have not been disclosed. The fact that the company is backed by Samsung, Intel and Tokyo Electron (TEL) has drawn attention.

Wafer metrology is the eyes of semiconductor production. During the process of stacking circuits layer by layer, even a slight warp or uneven stress in the wafer can easily turn the chips on it into defects. Until now, this market has been dominated by US-based KLA with an overwhelming share. KLA's tools are strong in areas such as long-proven stability on high-volume production lines, the ability to measure the front and back sides simultaneously, comprehensive metrology that includes thickness data, and integration with fab process control. For domestic companies, the structure has relied on KLA as the sole source of core metrology. That is why the emergence of another supplier is significant in itself.

Wooptix's technology is based on a method called “wavefront phase imaging (WFPI).” By reading how the wavefront of light changes across a wafer's surface, it measures shape, warp, nanotopography and stress in a single pass. The key point is that it measures the entire wafer in a single shot. The company emphasizes that the method is less sensitive to vibration and can measure wafers in the “mid-process” stage, after patterns or oxide films have already been deposited. Speed and precision are the strengths the company promotes. However, these are characteristics described by the company and in press reports, and no independent results comparing it side by side with KLA in a mass-production environment have been confirmed yet.

For that reason, the technology's most promising application is advanced packaging. In products such as high-bandwidth memory (HBM), which stacks chips vertically, yield is determined by microscopic voids between layers, chip lift-off, chip flatness and the degree of wafer warpage after bonding. Wooptix believes it can precisely detect these problems. The technology is also used for checking layer alignment in advanced logic processes, but the consensus is that its applications in packaging are currently more significant. For this reason, Samsung Electronics, which runs both foundry and HBM businesses, and SK hynix, which leads the HBM market, are seen as priority partners.

Let us examine what this change actually offers, and to whom. The first benefit for domestic chipmakers is the option of having one more metrology supplier. Nothing changes immediately. What has been installed is a research system, and whether it will be adopted in production depends on the validation results. Wooptix installed its first fully automated tool in a cleanroom at the French research institute CEA-Leti in June, and plans to begin joint development with global chipmakers next year to expand supply to production lines. A company representative said, “Korea is a very important market for us because Samsung and SK hynix are there,” adding that “we are keeping open new possibilities for high-volume manufacturing (HVM).” The timing of its entry into production lines has not yet been disclosed.