Yoshihiro Hosoi

Advanced Surface Laminar Circuit using new composite materials

This paper introduces a newly developed Advanced Surface Laminar Circuit (Adv-SLC) packaging technology, which utilizes new composite materials. Adv-SLC is a buildup substrate technology designed to satisfy the requirements of the most advanced semiconductor chips. We have developed a new dielectric material that is a build-up layer composed of two different materials. We also used a new material for the core substrate composed of Liquid Crystalline Polymer (LCP) reinforced with glass cloth. The new build-up layer has the following reliable properties: it can maintain both conductivity and dielectricity under the conditions of both a line/space width of 10/10μm and a via diameter of 30μm. The new core substrate also has excellent reliable properties as follows: it can maintain both conductivity and dielectricity under the condition of both a through hole diameter of 60μm and a through hole pitch of 120μm. We were able to confirm that the formation of the new substrate with the aforementioned new design rules contributes to reduce the silicon chip size. Consequently, due to all of the aforementioned properties, Adv-SLC contributes to reduce thermal stress when we mount a flip chip.

Advanced Surface Laminar Circuits Using Newly Developed Resins

This paper introduces a newly developed advanced surface laminar circuit (Adv-SLC) packaging technology, which utilizes new composite materials. Adv-SLC is a build-up substrate technology designed to fulfill the requirements of the most advanced semiconductor chips. Our new dielectric material is a build-up layer composed of two different materials. We also used a new material for the core substrate, composed of liquid crystalline polymer reinforced with glass cloth. The build-up layer has the following, highly reliable properties: it can maintain both conductivity and dielectricity under the conditions of both a line/space width of 10/10 μm and a via diameter of 30 μm . The core substrate also has excellent, reliable properties: it can maintain both conductivity and dielectricity under the conditions of a through hole diameter of 60 μm and a through hole pitch of 120 μm. We were able to confirm that the formation of the new substrate with the aforementioned new design rules contributes to reduce the size of the silicon chip. Consequently, Adv-SLC contributes to reduce thermal stress when mounting a flip chip.

Interface Formation Between Metal and Polyimide in High Wiring Density Build-up Substrate

A key to a high-wiring-density build-up substrate is fine circuitry formation technology to satisfy the ever-increasing demands for miniaturization of electronics products. The surface roughness of a dielectric layer needs to be in the submicrometer scale for fine circuitry such as a line less than 10 μm wide. However, the Cu to dielectric adhesion strength of such a line would not be sufficient to prevent peeling off during manufacture and after heat treatment. Consequently, it is essential to have good adhesion between Cu and dielectric layer with chemical bonds between the metal and the dielectric layer. A polyimide film was introduced as a dielectric layer in a build-up substrate. Argon plasma-modified polyimide surfaces were sputtered with NiCr and then subjected to Cu electroplating. While unmodified polyimide had a weak adhesion strength of 0.12 kN m-1, Ar plasma-modified polyimide showed good adhesion strength of more than 0.5 kN m-1 even after 10 days of heat treatment at 172°C. X-ray photoelectron spectroscopy studies revealed that the adhesion strength was attributable to chemical bonds between Cr and the polyimide. Ar plasma-treated polyimide produced a large quantity of oxygen functional groups containing C=O bonds on the surface of polyimide, and subsequent NiCr sputtering produced C-O-Cr or C=O⋯Cr bonds to the polyimide. In addition, NiCr sputtering also attacked some of N-C=O and N-C bonds, and modified them to produce C-N-Cr or C-N⋯Cr bonds to the polyimide. These two types of mechanism produced sufficiently high Cu to polyimide adhesion to achieve fine line circuitry.