Article comprising a stable, low-resistance ohmic contact

Details Article comprising a stable, low-resistance ohmic contact Article comprising a stable, low-resistance ohmic contact

1998-01-31

2001-04-24

Sanghavi, Hemang (Department: 2874)

Coherent light generators

Particular active media

Semiconductor

C372S044010, C372S050121, C257S741000, C257S745000, C257S747000, C257S750000

Reexamination Certificate

active

06222863

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to semiconductor devices. More particularly, the present invention relates to a stable, reliable contact for use in electronic and opto-electronic devices and circuits.
BACKGROUND OF THE INVENTION
Most semiconductor devices require an electrical contact for receiving electrical charge. Such a contact typically includes an upper “bonding” layer of metal that is in electrical connection with a wire that delivers the electrical charge. The bonding layer is also in electrical connection with a “cap” layer of the semiconductor device. The cap layer is formed from semiconductor material, and is in electrical contact with underlying semiconductor device layers. In that manner, electrical charge is delivered to the semiconductor device.
The electrical contact creates a metal (bonding layer)/semiconductor (cap layer) interface. The contact is identified as “ohmic” when electrical charge (i.e., electrons) is free to move across the metal-semiconductor interface.
Semiconductor device performance and reliability depend, in large part, on the “quality” of the interface or contact. Instability in prior art ohmic contacts (actually, in the metal layers serving as the contact to the semiconductor materials) has been associated with semiconductor device degradation. Such instability is caused, at least in part, by the tendency of the various layers of the ohmic contact to chemically react, over time, with one another.
A need therefore exists for an improved ohmic contact having substantially no tendency for continued reaction after the contact is formed.
SUMMARY OF THE INVENTION
A highly-stable ohmic contact, and improved semiconductor articles and opto-electronic circuits incorporating same, are disclosed. An ohmic contact in accordance with an illustrative embodiment of the invention comprises a plurality of thermodynamically-stable layers and layer interfaces. In an illustrative embodiment of the inventive method, those layers and layer interfaces are formed by providing a structure comprising multiple, appropriately-thick and specifically-organized layers of suitably-selected material, and exposing the structure to heat to cause reactions to take place between the various layers. Due to the thermodynamic stability of the resulting reacted layers and the interfaces between such layers, there is substantially no tendency for further reaction to occur within the ohmic contact.
In some embodiments, opto-electronic devices, such as lasers, advantageously incorporate the present ohmic contact. Moreover, in other embodiments, semiconductor devices requiring precise control of zinc diffusion advantageously incorporate the present ohmic contact. Regarding the latter application, it has been found that diffusion of the ubiquitous p-dopant zinc in, for example, a capped mesa buried heterostructure laser, occurs primarily during growth of the laser's cap layer. Minimizing cap layer thickness, down to about 1000 angstroms, minimizes zinc diffusion. Due to its reaction-limiting stability, the present ohmic contact enables use of such thin cap layers.


REFERENCES:
patent: 4374012 (1983-02-01), Alderstein
patent: 5260603 (1993-11-01), Kamura et al.
patent: 5523623 (1996-06-01), Yanagihara et al.
Okada et al., “Electrical Characteristics and Reliability of Pt / Ti / Pt / Au Ohmic Contacts to p-Type GaAs,” v.30, n.4A Jpn. J. App. Phys., pp. L558-L560 (Apr. 1991).
Sugiyama et al., “Ultra-Low Resistance Base Ohmic Contact with Pt / Ti / Pt / Au for High-ƒmaxAlGaAs / GaAs Heterojunction Bipolar Transistors,” v.33, Part 1, n. 1B, pp. 786-789 (Jan. 1994).

Affiliated with

Also associated with

Rating

Article comprising a stable, low-resistance ohmic contact does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Article comprising a stable, low-resistance ohmic contact, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Article comprising a stable, low-resistance ohmic contact will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2501019