Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2000-02-28
2002-07-16
Ghyka, Alexander G. (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S685000, C438S688000, C204S192150, C204S192170, C204S298120
Reexamination Certificate
active
06420263
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates generally to the field of semiconductor processing. More particularly, the present invention provides a method of producing aluminum lines on a substrate which prevents lateral extrusions between the lines, and the device so formed.
2. Related Art
When forming metal lines, a general three step process is often used. First, metal layers are formed on a substrate by sputtering a specific sequence of metals, including aluminum. Second, the desired metal lines are formed by photolithographically etching the metal layers. Third, the substrate is annealed to set the lines. Conventional sputtering techniques, however, tend to produce lateral extrusions during the photolithographic and annealing steps of the aluminum line formation process. These lateral extrusions may produce metal shorts between the aluminum lines. This becomes increasingly problematic as the devices become smaller, which forces the metal lines closer together. In addition, lateral extrusions pose reliability concerns-due to the metal “opens” or voids which may be produced within the metal lines due to volume changes.
Therefore, there exists a need in the industry for a method of forming aluminum metal lines on a substrate which prevents lateral extrusions between the aluminum metal lines.
SUMMARY OF THE INVENTION
The present invention provides a method of forming a semiconductor device that solves the above stated problems, and the device so formed.
The present invention provides a method for controlled deposition of aluminum onto a substrate, comprising the steps of: providing a substrate; heating the substrate to a temperature less than about 200° C.; providing a target from which aluminum is released; and sputtering aluminum onto the substrate, wherein the sputtering step includes controlling a power density to the target to be less than about 11 W/cm
2
. This aspect allows for the reduced production of lateral extrusions during the formation of the aluminum lines of a semiconductor device. This aspect further provides for reduced occurrences of shorts within the device. This aspect also provides a clampless deposition procedure without the need for temperature control, and wherein the power density to the target is controlled to be less than 11 W/cm
2
.
The second general aspect provides a method of forming aluminum lines, comprising the steps of: providing a substrate; heating the substrate to a temperature less than about 200° C.; and sputtering aluminum from a target onto the substrate, wherein the sputtering comprises control of a power density to the target to be less than about 11 W/cm
2
. This aspect allows for advantages similar to those associated with the first aspect.
The third general aspect provides a method of reducing lateral extrusion in aluminum lines on a substrate, comprising the steps of: providing a substrate; heating the substrate to a temperature less than about 200° C.; and sputtering aluminum from a target onto the substrate, wherein the sputtering comprises control of a power density to the target to be less than about 11 W/cm
2
. This aspect allows for advantages similar to those associated with the first aspect.
The fourth general aspect provides a semiconductor device having reduced lateral extrusions produced therein during the formation of aluminum lines. This aspect provides a semiconductor device produced using the method of, and possessing advantages similar to, the first aspect.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention.
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patent: 5358615 (1994-10-01), Grant et al.
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patent: 5700718 (1997-12-01), McTeer
patent: 5705429 (1998-01-01), Yamaha et al.
Cheek Roger W.
Dunbar, III George A.
Geffken Robert M.
Murphy William J.
Tiwari Prabhat
Ghyka Alexander G.
Schmeiser Olsen & Watts
Walsh Robert A.
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