Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1998-02-25
2001-08-14
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
06274292
ABSTRACT:
TECHNICAL FIELD
The invention pertains to semiconductor processing methods, such as, for example, methods of patterning photoresist in which an antireflective material is utilized to attenuate (for example, absorb) radiation.
BACKGROUND OF THE INVENTION
Semiconductor processing frequently involves providing a photoresist layer over a substrate. Portions of the photoresist layer are subsequently exposed to light through a masked light source. The mask contains clear and opaque features defining a pattern to be created in the photoresist layer. Regions of the photoresist layer which are exposed to light are made either soluble or insoluble in a solvent. If the exposed regions are soluble, a positive image of the mask is produced in the photoresist. The photoresist is therefore termed a positive photoresist. On the other hand, if the non-irradiated regions are dissolved by the solvent, a negative image results. Hence, the photoresist is referred to as a negative photoresist.
A difficulty that can occur when exposing photoresist to radiation is that waves of radiation can propagate through the photoresist to a layer beneath the photoresist and then be reflected back up through the photoresist to interact with other waves propagating through the photoresist. The reflected waves can constructively and/or destructively interfere with other waves propagating through the photoresist to create periodic variations of light intensity within the photoresist. Such variations of light intensity can cause the photoresist to receive non-uniform doses of energy throughout its thickness. The non-uniform dose can decrease the accuracy and precision with which a masked pattern is transferred to the photoresist. Also, the radiated waves reflected back from a non-flat surface underlying photoresist can enter portions of the photoresist that are not supposed to be exposed. Accordingly, it is desired to develop methods which suppress radiation waves from being reflected by layers beneath a photoresist layer.
A method which has been used with some success to suppress reflected waves is to form an antireflective material beneath a photoresist layer. Antireflective materials can, for example, comprise materials which absorb radiation, and which therefore quench reflection of the radiation.
Antireflective materials absorb various wavelengths of radiation with varying effectiveness. The wavelengths absorbed, and the effectiveness with which they are absorbed, vary depending on the materials utilized. The number of materials available for use as antireflective materials is limited. Accordingly, it is desired to develop alternative methods of varying the wavelengths absorbed, and effectiveness with which the wavelengths are absorbed, for antireflective materials.
SUMMARY OF THE INVENTION
In one aspect, the invention includes a semiconductor processing method wherein an antireflective material layer is formed over a substrate. At least a portion of the antireflective material layer is annealed at a temperature of greater than about 400° C. A layer of photoresist is formed over the annealed antireflective material layer. The layer of photoresist is patterned. A portion of the antireflective material layer unmasked by the patterned layer of photoresist is removed.
In another aspect, the invention includes a semiconductor processing method wherein an antireflective material layer is formed over a substrate. The antireflective material layer is annealed at a temperature of greater than about 400° C. A layer of photoresist is formed over the annealed antireflective material layer. Portions of the layer of photoresist are exposed to radiation waves, some of the radiation waves are attenuated by the antireflective material as the portions are exposed.
In yet another aspect, the invention includes a semiconductor processing method wherein a solid antireflective material layer is formed over a substrate. Optical properties of the antireflective material layer are altered. After altering the optical properties, a layer of photoresist is formed over the antireflective material layer. Portions of the layer of photoresist are exposed to radiation waves. Some of the radiation waves are absorbed by the antireflective material.
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Glass Tom
Holscher Richard
Yin Zhiping
Duda Kathleen
Micro)n Technology, Inc.
Wells, St. John, Roberts Gregory & Matkin P.S.
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