A new packaging concept for high density memory modules

High-density memory modules have been fabricated utilizing a novel LSI interconnection method. A novel LSI chip whose bonding pads are formed on the device active area is created by an on-device multilayer wiring process, consisting of forming a polyimide insulating layer and thin-metal-film conductor layers (Ti/Ni/Au), which have new pads for connection. A feasibility study and defect analysis of the polyimide insulating layer and the conductor layers have been carried out to establish the process for this LSI chip. The influence of four process steps on the device characteristics was evaluated using AC/DC parameters and TEG parameters. Five kinds of reliability tests, a high-temperature storage test, a high-temperature and high-humidity test, a temperature cycle test, a high-temperature-operation test, and a high-temperature-bias test, were carried out. The chip satisfied the specifications and passed the reliability tests