Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1998-06-15
2001-03-13
Duda, Kathleen (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S950000
Reexamination Certificate
active
06200734
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to semiconductor devices, and in particular to the fabrication of semiconductor devices in integrated circuits using photolithography.
BACKGROUND OF THE INVENTION
The use of photolithography in the fabrication of semiconductor integrated circuits is well-established in the industry. Such techniques involve covering the semiconductor substrate with a photoresist material, exposing the photoresist to light through a mask including a desired pattern, and developing the photoresist so that the pattern is formed in the resist. The semiconductor can then be etched or materials deposited using the photoresist as a mask.
One of the challenges in this technology is to control feature sizes in the photoresist when the semiconductor substrate has a varying topology. For example, photoresist material is often formed over an existing gate oxide pattern on the substrate. Light incident on the photoresist which is reflected by the gate over thicker portions of oxide will travel a shorter distance than light reflected by the thinner oxide portions. These reflected rays, therefore, will form different interference patterns with light reflected by the top of the photoresist layer, thereby causing a variation in the intensity of light exposing the photoresist. The variations in exposure cause variations in the dimensions of the features defined by the photoresist.
One recent proposal for solving these problems involves forming an anti-reflection coating having a variable index of refraction over the semiconductor substrate. In one embodiment, the anti-reflection coating is made of a silicon-containing oxide with the index of refraction varied by varying the amount of silicon relative to the amount of oxide. (See U.S. Patent Application of Cirelli and Weber, Ser. No. 08/611595, filed on Mar. 7, 1996, now abandoned which is incorporated by reference herein.)
Building on this teaching, what is desired are anti-reflection coating stacks which provide optimum reflectivity control for various circuit topologies.
SUMMARY OF THE INVENTION
The invention is a method of fabricating semiconductor devices which includes the step of forming an anti-reflection coating on a substrate having a non-planar surface. The anti-reflection coating includes at least two layers of a silicon-containing oxide having different ratios of silicon-to-oxide, which will produce different indices of refraction, and different extinction coefficients. A layer of energy-sensitive material is formed over the coating and exposed to radiation to introduce a patterned image into the energy-sensitive material. A first oxide layer adjacent to the substrate has an extinction coefficient in the range 0.7 to 1.9 as measured at the exposure wavelength, and a second oxide layer adjacent to the energy-sensitive material has an index of refraction within the range 1.7 to 2.0 as measured at the exp wavelength.
REFERENCES:
patent: 5580701 (1996-12-01), Lur et al.
patent: 5674356 (1997-10-01), Nagayama
patent: 5719072 (1998-02-01), Sugiura et al.
patent: 5733712 (1998-03-01), Tanaka et al.
patent: 5747388 (1998-05-01), Kusters et al.
patent: 5759746 (1998-06-01), Azuma et al.
Blatchford, Jr. James W.
Kane Brittin Charles
Steiner Kurt George
Duda Kathleen
Lucent Technologies - Inc.
LandOfFree
Method for fabricating semiconductor devices does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for fabricating semiconductor devices, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for fabricating semiconductor devices will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2494929