1.1 Integration Technology

The "big bang" of electronics can be traced to the invention of the first point-contact transistor in 1947 by J. Bardeen, W. Brattain, and W. Shockley [8]. The transistor is an active electrical component in an integrated circuit which acts as a switch. The invention of the transistor was considered a revolution and it quickly replaced the vacuum tube, on which much of the electronics at the time were based [117].

The development of several types of semiconductor devices followed in the years after the invention of the first transistor [122]. Electrical engineers realized advanced electrical circuits consisting of discrete components connected together with metal traces [117]. Although these innovative devices could be more reliable compared to the pre-transistor era electronics, problems started to arise as the complexity of the circuits grew. In particular, limitations on performance due to the size of the interconnect wires, as well as the impossibility to assemble the vast number of tiny components required in the circuit, limited the full exploitation of the device capabilities.

A solution to the problem of increasing circuit complexity was found in 1958 by J. S. Kilby [90], whose groundbreaking idea was to make all components of the electrical circuit out of the same block of semiconductor material and add the metal connection as a layer on top of. This resulted in the well-known integrated circuit (IC). The integration of all necessary devices within silicon no longer required individual discrete components and wires which must be assembled manually.

Later improvements in the fabrication process of ICs were achieved at Intel under the supervision of G. Moore and R. Noyce [54]. In order to make the IC more suitable for mass production and answer to the profound need of more general and broader application, they introduced the concept of a microprocessor in 1971 by releasing the Intel 4004, the first central processing unit (CPU) [54].

ICs and microprocessors have significantly improved since Kilby's prototype, demonstrating higher performance and enhanced reliability.


M. Rovitto: Electromigration Reliability Issue in Interconnects for Three-Dimensional Integration Technologies