Beam lead technology
Beam lead technology is a method of fabricating a semiconductor device. Its original application was to high-frequency silicon switching transistors and high-speed integrated circuits. It eliminated the labor-intensive wire-bonding process used for integrated circuits at the time and allowed automated assembly of semiconductor chips onto larger substrates to produce hybrid integrated circuits. [1]
History[]
In the early 1960s, M.P. Lepselter[2][3] developed the techniques for fabricating a structure consisting of electroforming an array of thick, self-supporting gold patterns on a thin film Ti-Pt Au base, hence the name "beams", deposited on the surface of a silicon wafer. The excess semiconductor from under the beams was removed, thereby separating the individual devices and leaving them with self-supporting beam leads or internal chiplets cantilevered beyond the semiconductor. The contacts served as electrical leads in addition to also serving the purpose of structural support for the devices.
Patents[]
Patented inventions included:
- Selective Removal of Material Using Cathodic Sputtering (Plasma Etching/RIE), US Patent #3,271,286; issued 1966
- PtSi Semiconductor Contacts and Schottky Diodes (PtSi Schottky Diodes), US Patent #3,274,670; issued 1966
- Semiconductive Device Including Beam Leads (Beam Leads, Ti-Pt-Au metal system), US Patent #3,426,252; issued 1969
- Method for Making Closely Spaced Conductive Layers (Air-Insulated Crossovers, air bridges, RF-Switch), US Patent #3,461,524; issued 1969
- Vibratory Reed Device (MEMS), US Patent #3,609,593; issued 1971
Legacy[]
This technology, also known as air-bridge technology, has established itself for its unsurpassed reliability in high-frequency silicon switching transistors and ultra-high-speed integrated circuits for telecommunications and missile systems. The beam lead devices, produced by the hundreds of millions, became the first example of a commercial microelectromechanical structure (MEMS).
References[]
- ^ Rao R. Tummala et al, Microelectronics Packaging Handbook: Semiconductor packaging, Springer, 1997 ISBN 0-412-08441-4, page 8-75
- ^ M.P. Lepselter, et al., "Beam-Lead Devices and Integrated Circuits", Proceedings of the IEEE, Vol. 53 No 4 (1965), p.405.
- ^ Presentation at Electron Devices Meeting, October 29, 1964, Washington, D.C.
- Beam Lead Technology, M.P.Lepselter, Bell System Technical Journal 45. (2) (1966), pp. 233–253
- American inventions
- Semiconductor device fabrication