Guo Xueping

Fabrication of PN junction capacitor using SiP technology on Si-based interposer wafer

The article relates to the fabrication of embedded P-N junction capacitors, using System-in-Package (SiP) technology, on a silicon interposer wafer with Through-Silicon-Via (TSV). The P-N junction capacitors are fabricated using current micromachining technologies, including etching high aspect-ratio, three-dimensional honeycomb structure and thermal oxidation, thermal dopant diffusion, sputtering, and metallization and so on. The fabricated capacitor displays high capacitance density compared with common two-dimensional (2D) P-N junction capacitors. Tests at high frequency (10 Mhz–40 GHz) were conducted to evaluate the properties of these capacitors. Test results show that the capacitors have a high capacitance density up to 12nF/mm2 of wafer area, with reverse bias voltage of 1V, which is about 10–12 times that of 2D semiconductor capacitors, and is attributed to the increased junction area inherent in the three-dimensional via structure. These capacitors can be used for decoupling under a wide frequency range from 300 MHz to 3.2 GHz. they show a low parasitic inductance by measuring. Capacitor has a characteristic that capacitance value also keeps up constant with the increase of frequency.

Characteristics of high frequency and high density through silicon vias (TSVs)

TSV has now been a hotspot of the industry for years. Comparing with the wire-bonding, the technology populated in the last decade, Through Silicon Via (TSV) has merits of shorter wiring route, better signal integrity, larger bandwidth, lower power consumption and smaller packaging size. Undoubtedly, the TSV is treated by the industry to be the next generation of packaging solution to replace the wire-bonding. However, the TSV engineering has to conquer several difficulties, e.g. drilling technique, via filling technique, via filling material, stacking and bonding technique, and handling after the wafer thinning, etc. Therefore the standardization of the TSV still has a long way to go. This paper illustrates the initial achievement concerning with via filling material and corresponding high frequency and high density advantages that acquired by Institute of Microelectronics, Chinese Academy of Sciences.