Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-11-05
2001-02-20
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S624000, C438S634000, C438S637000, C438S671000, C438S952000
Reexamination Certificate
active
06191030
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and a method for patterning a semiconductor device. In particular, the present invention relates to an apparatus and a method for patterning a semiconductor device using an anti-reflective coating layer.
2. Description of the Related Art
As semiconductor device sizes shrink, the formation of accurately-sized contact regions using lithographic images becomes more important. Conventional lithographic techniques involve depositing an underlayer, such as a metal film layer
20
, onto a semiconductor substrate
10
. A metal film layer
20
is shown in FIG.
1
. Then, a photo-resist (or resist) layer
30
is spin-coated onto the underlayer
20
. The photo-resist layer
30
is then patterned using a conventional patterning. For example, as shown in
FIG. 1
, light is shined down onto the semiconductor substrate
10
from above, using a photo-lithographic mask (or reticle)
40
, in order to pattern the photo-resist layer
30
to a desired pattern. The photo-lithographic mask
40
is constructed, for example, with a glass plate and with a chromium metal layer disposed onto portions of the glass plate where a photo-resist layer, which is situated between the mask
40
and a substrate, is not to be exposed to light from the light source.
As shown in
FIG. 1
, the reticle
40
has a width of W
1
, which is the desired size of a gap to be placed in the photo-resist layer
30
, so as to provide a contact region or the like to the underlayer
20
. However, due to reflections of light from the top surface of the underlayer
20
, some of the light reflects upwards and in a skewed direction, thereby exposing more of the photo-resist layer
30
to the light than is desired. This problem has been found by the inventors, and results in an “exposed” photo-resist width of W
2
, which is greater than the desired width of W
1
.
FIG. 2
shows the result of the problems caused by the reflected light during the photo-lithographic step, in which a gap of W
2
is formed in the photo-resist layer
30
after developing of the photoresist due to the light being exposed onto it, with the actually-obtained gap having a width of W
2
that is larger than the desired gap of W
1
.
Thus, in the conventional photo-lithographic process, contact points made for an underlayer can sometimes be larger than desired, due to unwanted reflections of light during the patterning of the photo-resist. This is undesirable, and can result in defective operation of semiconductor devices.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method of creating a contact region to an underlayer of a semiconductor device, where the contact region is substantially uniform in size.
Another object of the present invention is to provide an apparatus for causing less light to reflect during a photo-lithographic step, to thereby obtain a contact region of a desired width.
To achieve these and other objects, the present invention is directed to a first method for creating a contact points to a lower layer of a semiconductor device. The method includes a step of applying an anti-reflective coating onto the lower layer. The method also includes a step of applying a resist onto the anti-reflective coating layer. The method further includes a step of patterning the resist to a particular pattern, with the patterning being performed by a photo-lithographic process using a mask. The method also includes a step of etching the anti-reflective coating layer in accordance with the particular pattern of the resist. The method further includes a step of etching the underlayer in accordance with the etched anti-reflective coating layer and the particular pattern formed on the resist layer. The method still further includes a step of removing the anti-reflective coating layer and the resist using a same etch-removal chemistry.
The present invention is also directed to a second method for creating a contact point to an underlayer of a semiconductor device. The method includes a step of applying an anti-reflective coating onto the lower layer. The method further includes a step of applying a silicon-based dielectric layer onto of the anti-reflective coating layer. The method also includes a step of applying a resist onto the silicon-based dielectric layer. The method further includes a step of patterning the resist to a particular pattern, with the patterning being performed by a photo-lithographic process using a mask. The method also includes a step of etching the silicon-based dielectric layer. The method also includes a step of etching the anti-reflective coating layer in accordance with the particular pattern of the resist. The method further includes a step of removing the resist layer. In an optional step, the silicon-based dielectric layer is removed. In the second method, unlike the first method, the anti-reflective coating layer remains on the semiconductor device after the manufacturing of the device, and serves and an interlayer dielectric during operation of the device, as well as serving as an anti-reflective layer during manufacturing of the device.
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Gallardo Ernesto A.
Pangrle Suzette K.
Pellerin John G.
Subramanian Ramkumar
Advanced Micro Devices , Inc.
Foley & Lardner
Niebling John F.
Zarneke David A.
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