Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
2000-05-09
2001-09-18
Utech, Benjamin L. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S723000, C438S734000, C438S743000
Reexamination Certificate
active
06291359
ABSTRACT:
TECHNICAL FIELD
This invention relates to methods of forming contact openings and to methods of controlling the degree of taper of contact openings.
BACKGROUND OF THE INVENTION
When integrated circuitry is formed, contact openings are often formed through insulative material for establishing electrical communication with the integrated circuitry. Such contact openings are typically subsequently filled with conductive material, such as a metal or polysilicon, whereby electrical communication is established with the integrated circuitry.
Contact openings are often formed to be fairly narrow; and, it is desirable from a design standpoint to form the contact openings to have sidewalls which are as near vertical as possible. This helps to ensure that the contact area at the bottom of the contact opening is sufficiently large to desirably cover and/or expose conductive material with which electrical communication is desired. As aspect ratios, i.e. the height-to-width ratio, of contact openings increase, it becomes increasingly important to ensure that the dimension of the bottom of the contact opening is sufficiently large to provide adequate coverage for conductive material which is subsequently formed therein. For narrow contact openings, such is accomplished by maintaining the sidewalls of the contact opening as near vertical as possible.
Referring to
FIGS. 1 and 2
, two exemplary contact opening etch profiles are indicated generally at
100
,
100
a
respectively.
FIG. 1
shows a substrate
102
with a layer of insulative material
104
formed thereover. A masking layer
106
such as photoresist is formed over insulative material
104
and is subsequently patterned to define a contact opening pattern. Contact opening
108
is etched using an etch which is highly selective relative to masking layer
106
. Hence, while a desirably high level of selectivity ensures that masking layer
106
remains over the substrate, the subsequent etch profile is unsatisfactorily tapered.
FIG. 2
shows a substrate
100
a
in which like numbers from
FIG. 1
have been utilized with the suffix “a”. There, a contact opening
108
a
is etched through layer
104
a
using an etch with a comparatively lower degree of selectivity relative to an overlying masking layer (not shown). The lower degree of selectivity results in a contact opening profile with a more desirable degree of taper. Yet, the overlying masking layer can be completely removed, thereby undesirably opening up other substrate features to etching.
This invention arose out of concerns associated with providing methods of forming contact openings having sidewalls which are generally vertical within desired tolerances. This invention also arose out of concerns associated with providing methods for controlling the degree of taper of contact openings.
SUMMARY OF THE INVENTION
Methods of forming contact openings and methods of controlling the degree of taper of contact openings are described. In one implementation, a layer is first etched through a contact mask opening using a first set of etching conditions. The etching conditions provide a first degree of sidewall taper from vertical, if etching completely through the layer. After the first etching, the layer is second etched through the contact mask opening using a second set of etching conditions. The second set of etching conditions provide a second degree of sidewall taper from vertical, if etching completely through the layer. The second degree of sidewall taper is different from the first degree of taper. In another embodiment, a material through which a contact opening is to be etched to a selected depth is formed over a substrate. A masking layer having an opening therein is formed over the material. The material is first etched through the opening with the first etch having a first selectivity relative to the masking layer. After the first etch, and at a depth which is less than about 50% of the selected depth, the material is second etched, with the second etch having a second selectivity relative to the masking layer which is greater than the first selectivity. In a preferred implementation, the second degree of selectivity is achieved by modifying an etch parameter during the etching of the contact opening.
REFERENCES:
patent: 4162185 (1979-07-01), Coburn et al.
patent: 4671849 (1987-06-01), Chen et al.
patent: 4807016 (1989-02-01), Douglas
patent: 4814041 (1989-03-01), Auda
patent: 5021121 (1991-06-01), Groechel et al.
patent: 5310454 (1994-05-01), Ohiwa et al.
patent: 5420077 (1995-05-01), Saito et al.
patent: 5746884 (1998-05-01), Gupta et al.
patent: 5750441 (1998-05-01), Figura et al.
patent: 6074957 (2000-06-01), Dorhoe et al.
Donohoe Kevin G.
Stocks Richard L.
Deo Duy-Vu
Micro)n Technology, Inc.
Utech Benjamin L.
Wells, St. John, Roberts Gregory & Matkin P.S.
LandOfFree
Methods of forming openings and methods of controlling the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods of forming openings and methods of controlling the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods of forming openings and methods of controlling the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2526504