A research group led by Prof. CHEN Chilai from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences (CAS) has developed Through Glass Via (TGV) process for three dimensional (3D) advanced packaging, enabling low transmission loss and high vacuum wafer-level packaging of high-frequency chips and Microelectro Mechanical Systems (MEMS) sensors.

3D packaging technology has become one of the main driving forces for the development of integrated circuits. TGV is a new vertical interconnection technology applied in wafer-level vacuum packaging. It has good electrical, thermal and mechanical properties, and achieves interconnection with the shortest distance and the minimum spacing between chips. 

"We have overcome technical problems such as the manufacture of high-uniformity glass micropore arrays, glass dense reflow, and high-density filling of glass micropores and metals," said Dr. LI Shan, who conducted the research.

The researchers proposed a new TGV wafer manufacturing scheme. The newly-developed TGV wafers boasted high uniformity, high density and high aspect ratio, which enabled ultra-low leakage rate and ultra-low signal loss. After testing, they found that some parameters were even better than international standards.

"They can be applied to 5G/6G high-frequency chips such as ring resonators, waveguide slot antennas, millimeter-wave antennas, as well as new 3D packaging requirements for MEMS gyroscopes and accelerometers." said Dr. LI Shan, "and we can make different sizes according to requirements."

Related technologies have been supported by projects from the National Natural Science Foundation of China, the Ministry of Science and Technology, CAS, and Anhui Province.

Figure 1. Conductive metal-based TGV wafers. (Image by HFIPS)

Figure 2. Conductive silicon-based TGV wafers. (Image by HFIPS)