Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Removal of imaged layers
Reexamination Certificate
2000-11-13
2003-04-15
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Removal of imaged layers
C430S328000, C430S311000, C430S322000, C430S318000, C134S001100, C134S001200
Reexamination Certificate
active
06548231
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to methods used to fabricate semiconductor devices, and more specifically to a method used to remove masking photoresist shapes, and polymer layers formed during dry etch definition of metal structures.
(2) Description of Prior Art
Micro-miniaturization, or the ability to fabricate semiconductor structures comprised with sub-micron features, have resulted in performance enhancements for semiconductor devices. The attainment of devices with sub-micron features has been realized via advancements in several semiconductor fabrication disciplines, such as photolithography and dry etching. The development of more sophisticated exposure cameras, and of more advanced photosensitive materials have allowed sub-micron features to be routinely formed in masking photoresist layers. In addition the continuing evolvement of dry etching tools and processes, have allowed the sub-micron images in photoresist layers to be easily transferred to underlying materials, such as metal or insulator layers, used to build the desired semiconductor device. However to successfully define sub-micron features in a material such as a metal layer, the dry etching reactants have to possess high selectivity between the masking photoresist shape and the metal layer, as well as high selectivity between the metal being defined, and the underlying material, allowing controllable dry etch end point to be achieved, The desired selectivity is usually obtained via use of a dry etch ambient which forms a non-etchable polymer type layer at the dry etching end point, allowing protection of materials underlying the now defined metal shape to be achieved. The polymer layer also forms on the exposed sides of the defined metal shape, protecting the metal shape from any isotropic component of the dry etch procedure. The polymer layer, comprised of halogens from the dry etching reactants, such as chlorine, is removed during the process used to remove the masking photoresist shapes. However if the photoresist removal process is not optimized, chlorine emanating from the polymer layer can attack, and corrode the exposed surfaces of the defined metal shape, resulting in yield and reliability loss.
This invention will teach a two step procedure for successfully removing the masking photoresist shape, as well as the chlorine containing polymer layer, in which process conditions of a first step of the two step procedure, such as RF power, substrate temperature, and reactant ratio, are optimized to allow removal of the corrosion causing chlorine feature from the polymer layer to be achieved. Prior art, such as Ramachandran et al, in U.S. Pat. No. 5,980,770, as well as Lee et al, in U.S. Pat. No. 6,080,680, describe methods for removing photoresist shapes as well as polymer layers, however those prior-arts do not employ the unique two step removal procedure, featuring the unique set of process conditions of the first step of the procedure, that are described in this present invention.
SUMMARY OF THE INVENTION
It is an object of this invention to use a two step passivation, and strip procedure to remove masking photoresist shapes and polymer layers, formed on defined metal structures at the conclusion of a metal defining, dry etch procedure.
It is another object of this invention to employ a first step, of the two step passivation strip procedure that features a lower substrate temperature, a lower RF power, and an increased ratio of oxygen to water, when compared to the second step of the two step passivation procedure, to optimize the removal of the corrosive chlorine from the polymer layer, located at the wafer edge, during this initial stage of the removal of masking photoresist shapes and polymer layers.
It is yet another object of this invention to employ a higher substrate temperature, and a higher RF power, when compared to the first step of the two step passivation procedure, to remove chlorine from the polymer layer, located at the center of the wafer, using only water as a reactants.
It is still yet another object of this invention, after the two step passivation procedure, removing chlorine from the edges, and center, of a wafer, to strip the masking photoresist shape, followed by a clean procedure used to remove the polymer from the sides of the defined metal structure.
In accordance with the present invention a two step passivation procedure, used to remove chlorine from a polymer layer formed on the sides of a dry etched, metal structure, prior to removal of the masking photoresist shape and polymer layer, is described. A dry etching procedure, featuring a chlorine containing etchant, is used to define a metal shape, using an overlying photoresist shape as an etch mask. A first step of the two step passivation procedure is next employed, at specific conditions, to remove chlorine from the polymer layer, formed on the sides of the defined metal shape, in regions near the edge of the wafer of semiconductor substrate. The removal of corrosive chlorine, at the wafer edge, which can attack the defined metal structure, is removed using an increased oxygen—water ratio, and a lower substrate temperature, and a lower RF power, when compared to conditions used in the second step. The second step of the two step procedure is next performed in water only, at a higher substrate temperature, and at a higher RF power to remove corrosive chlorine from polymer residing on the sides of the defined metal shapes, located at the center of the wafer. A strip procedure is then employed to remove the masking photoresist shape, followed by a cleaning step used to remove polymer layer from the sides of the defined metal shape.
REFERENCES:
patent: 5545289 (1996-08-01), Chen et al.
patent: 5814155 (1998-09-01), Solis et al.
patent: 5925501 (1999-07-01), Zhang et al.
patent: 5980770 (1999-11-01), Ramachandran et al.
patent: 6080680 (2000-06-01), Lee et al.
patent: 6271115 (2001-08-01), Liu et al.
Goh Aik Hon
Goh Carol
Zhang Xin
Chacko-Davis Daborah
Chartered Semiconductor Manufacturing Ltd.
Huff Mark F.
Pike Rosemary L. S.
Saile George O.
LandOfFree
Enhanced passivation scheme for post metal etch clean process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Enhanced passivation scheme for post metal etch clean process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Enhanced passivation scheme for post metal etch clean process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3001731