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AssigneeSiemens Aktiengesellschaft
InventorsHubert Patalong, Eberhard F. Krimmel
Estimating the term…
A region of a semiconductor surface intended for a metal contact is scanned with a closely packed sequence of intense laser light pulses so as to generate a disturbed surface layer and a metal layer is then applied and alloyed into the semiconductor surface. The invention is particularly useful with silicon crystal surfaces orientated in the <100> direction, which for the manufacture of semiconductor components, such as thyristors having controllable short-circuits generated by integrated field effect transistors, are provided on their back side with an aluminum contact or a metal silicide contact.
In a method of producing alloyed metal contact layers on crystal-orientated semiconductor surfaces by means of pulsed energy irradiation, the improvement comprising wherein:
In a method of producing semiconductor components having a crystal-orientated semiconductor material with a front surface and a back surface, with a metal contact layer on such back surface, the improvement comprising wherein:
Dependencies are inferred from the claim text.
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Of electrodes ohmically coupled to a semiconductor: to Group IV semiconductors
Characterised by the materials: being Group IV materials, e.g. B-doped Si or undoped Ge
To Group IV semiconductors: using conductive layers comprising silicides
Electrodes characterised by their materials: electrodes ohmically coupled to a semiconductor
Term ended 4 Aug 2001 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The invention relates to a method of producing alloyed metal contact layers on crystal-orientated semiconductor surfaces by energy pulse irradiation.
2. Prior Art
FIGS. 1-4 are elevated partial cross-sectional views of an exemplary embodiment, illustrating certain sequential steps in accordance with the principles of the invention wherein an aluminum layer is utilized as a contact material.
FIGS. 5 and 6 are somewhat similar view of another embodiment wherein molybdenum silicide layer is utilized as the contact metal; and
FIGS. 7 and 8 are graphical illustrations showing the improvement of electrical parameters achieved by the practice of the invention.
In the drawings, identical reference numerals denote identical elements and the individual method steps of the invention are schematically illustrated and briefly explained on the basis of exemplary embodiments.
In FIG. 1, a silicon crystal wafer 1 having a surface orientated in the <100>-direction is irradiated, in a scanning manner, with sharply focused, intense laser light pulses 2 so as to generate craters or the like in a thin surface layer 3. The surface layer 3 generally consists of an extensive network of disclocation lines and polycrystallines which no longer offer the subsequent alloying any resistance.
As can be seen from FIG. 2, an aluminum layer 4 is applied onto the disturbed surface layer 3, for example, by vapor-deposition, sputtering, electrolytic precipitation or, preferably, by means of pressing an aluminum foil onto such surface. The applied metal layer is then alloyed into the semiconductor body. Initially, during heating, an aluminum-silicon melt 14 is formed (FIG. 3). During cooling, the aluminum-silicon melt 14 is converted into an aluminum-silicon eutectic 24 and a p-conductive silicon layer 5, as shown in FIG. 4.