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Fabrication for Multilayer Semiconductor Devices

IP.com Disclosure Number: IPCOM000077257D
Original Publication Date: 1972-Jul-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Chang, LL: AUTHOR [+4]

Abstract

Fig. 1 shows a molecular beam evaporation arrangement which can be utilized in the fabrication of PN and hetero-multilayer semiconductor devices including superlattices. The molecular beam epitaxy arrangement of Fig. 1 in conjunction with a mass analyzer connected to a process control computer, permits the formation of devices in which the deposition rates, constituents and thicknesses of the deposited layers can be controlled to a high degree.

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Fabrication for Multilayer Semiconductor Devices

Fig. 1 shows a molecular beam evaporation arrangement which can be utilized in the fabrication of PN and hetero-multilayer semiconductor devices including superlattices. The molecular beam epitaxy arrangement of Fig. 1 in conjunction with a mass analyzer connected to a process control computer, permits the formation of devices in which the deposition rates, constituents and thicknesses of the deposited layers can be controlled to a high degree.

In Fig. 1. beam sources 1 contain evaporants such as III-V compounds, their pseudobinary alloys, or other desired material which are heated by sources, not shown, to evaporate material onto substrate 2 either singly or in combination with other sources 1 under control of shutters 3 which, when deflected, permit the deposition of evaporants onto substrate 2. Chopper 4 which is interposed between evaporant beams from sources 1 and a residual gas analyzer (RCA) 5; otherwise known as a quadrupole mass spectrometer; interrupts and passes the evaporant beams in a cyclic manner. Analyzer 5 is utilized to monitor and distinguish between the various species being evaporated.

The output of mass analyzer 5 is connected, as shown in Fig. 2, via an IBM System 7 (or a passive foreign interface FIF), designated as 6, to an IBM Model 1130 computer, designated as 7. Heaters 8 shown surrounding beam sources 1 are controlled by computer 7 to adjust the power applied thereto, which in turn adjusts the evaporation rate of evaporants disposed within sources 1. Thermocouples, not shown, connected to sources 1 monitor the temperatures of sources 1 and feed data relating to temperature into the process control arrangement. The rotation rate of chopper 4 determines the overall timing cycle of the process control arrangement by sending sync pulses to the computer via SET CYCLE CONDUCTOR. The program steps which control the overall operation of the deposition system are controlled by timing pulses obtained from chopper 4. The resulting sync pulses are counted to determine real time for purposes of integrating the output of RGA unit 5. When chopper 4 rotates, the deposition beams are alternately blocked and permitted to pass to RGA 5. In this manner, RGA 5 is enabled to determine...