Coating apparatus – Projection or spray type – Plural projectors
Reexamination Certificate
2002-10-03
2004-02-10
Lorengo, J. A. (Department: 1734)
Coating apparatus
Projection or spray type
Plural projectors
C118S315000, C118S321000, C234S027000, C234S027000, C234S027000, C438S758000, C438S780000
Reexamination Certificate
active
06689215
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to the field of microelectronic fabrication. More particularly, the invention relates to methods and apparatus for improving the yield and line width performance of liquid polymers.
2. Discussion of the Related Art
Lithography process is one of the major drivers of semiconductor industry in its relentless progress in achieving smaller feature sizes with improved yields. More specifically, improved critical dimension (CD) control and reduced process-induced defect and particle counts need to be satisfied simultaneously.
The develop fluid module process plays a significant role in the patterning of increasingly smaller line widths. Regions of high and low dissolution rates are created on the resist film as a result of the sequence of photolithography process steps preceding the develop process. During a develop process, images transferred to the resists film are developed into three dimensional structures by a wet process. The subsequent etch process (mostly dry) transfers this image onto the substrate which may formed of Si, SiO
2
, poly Si, etc.
There are many variations of a good develop process which generally consists of two main parts. In the first part, a developer fluid is dispensed over a wafer spinning at a low rpm followed by a static puddle formation and a long static or oscillating step at which regions of high dissolution rate are etched away to create three-dimensional images on the film. The quality of patterned images, the value of side wall angles, and the CD control, are all strongly affected by this first part of the develop process. In the second part of the develop process, a chemical wet etch step is immediately followed by a deionized (DI) water rinse step that is mainly intended to wash away dissolved resist and developer fluid mixture with minimum particle and defect count on the patterned wafer. The rinse step is thus an extremely crucial process in improving the resulting yield of a lithography process.
Heretofore, the requirements of improved critical dimension control, reduced process-induced defect counts and reduced process-induced particle counts referred to above have not been fully met. What is needed is a solution that simultaneously addresses all of these and other related requirements.
SUMMARY OF THE INVENTION
The invention provides methods and apparatus for the reduction of cross-contamination of dispensed liquids during the develop process in lithography systems. A primary goal of the invention is to improve yield resulting from lithography processes. Another primary goal of the invention is to offer improved critical dimension (CD) control capability. Solutions are thus provided for these and other related problems encountered in conventional developer fluid modules of a wafer track tool system. It shall be understood that the particular features of the described embodiments in the following specification may be considered individually or in combination with other variations and aspects of the invention.
A first aspect of the invention is implemented in an embodiment that is based on a method for minimizing precipitation of developing reactant by lowering a sudden change in pH, said method comprising: developing at least a portion of a polymer layer on a substrate with a charge of developer fluid; then permitting at least a portion of said charge of developer fluid to dwell on said polymer so as to controllably minimize a subsequent sudden change in pH; and then rinsing said polymer with a charge of another fluid.
A second aspect of the invention is implemented in an embodiment that is based on a method for minimizing precipitation of developing reactant by lowering a sudden change in pH, said method comprising: developing at least a portion of a polymer layer on a substrate with an initial charge of a developer fluid; then rinsing said polymer with an additional charge of said developer fluid so as to controllably minimize a subsequent sudden change in pH; and then rinsing said polymer with a charge of another fluid.
A third aspect of the invention is implemented in an embodiment that is based on a method for minimizing precipitation of developing reactant by lowering a sudden change in pH, said method comprising: developing at least a portion of a polymer layer on a substrate with a charge of developer fluid; then contacting said substrate with a charge of buffer, thereby mixing at least a portion of said developer fluid with at least a portion of said charge of buffer, so as to controllably minimize a subsequent sudden change in pH; and then rinsing said polymer with a charge of another fluid.
A fourth aspect of the invention is implemented in an embodiment that is based on an apparatus for minimizing fluid impingement force on a polymer layer to be developed on a substrate, thereby improving yield and line width control performance, said apparatus comprising: a nozzle including: a manifold adapted to supply a fluid; a plurality of fluid conduits coupled to said manifold; and a plurality of tubular inserts located within said plurality of fluid conduits.
A fifth aspect of the invention is implemented in an embodiment that is based on an apparatus for minimizing fluid impingement force on a polymer layer to be developed on a substrate, thereby improving yield and line width control performance, said apparatus comprising: a nozzle including: a developer manifold adapted to supply a developer fluid; a plurality of developer fluid orifices coupled to said developer manifold; a rinse manifold adapted to supply a rinse fluid; and a plurality of rinse fluid orifices coupled to said developer manifold, wherein said developer manifold and said rinse manifold are staggered to reduce an exterior width of said nozzle.
A sixth aspect of the invention is implemented in an embodiment that is based on an apparatus for minimizing fluid impingement force on a polymer layer to be developed on a substrate, thereby improving yield and line width control performance, said apparatus comprising: a nozzle including: a developer manifold adapted to supply a developer fluid; a plurality of developer fluid orifices coupled to said developer manifold; a rinse manifold adapted to supply a rinse fluid; a plurality of rinse fluid orifices coupled to said rinse manifold, and said plurality of rinse fluid orifices arranged to define at least one rinse fluid axis, wherein said nozzle is connected to a bracket adapted to raise and lower said nozzle with regard to said substrate and reposition said at least one rinse axis so as to be substantially coplanar with a normal to a center of said substrate.
Additional aspects of the invention include methods and apparatus for mitigating cross-contamination between liquid dispensing jets in close proximity to a surface.
Some of the benefits provided by the invention includes the reduction of defect density during the develop process of a liquid polymer used in a photolithography step by employing new multi-port delivery apparatus with multi-dispense nozzles. An important aspect of the multi-port delivery apparatus herein is their ability to reduce droplet impact. This apparatus allows for the significant reduction of the defect density due to its superior rinsing action. In addition, this multi-port nozzle system allows two or more different developer fluid chemistries (in addition to a rinse chemistry) to be supported without any or reduced cross-contamination. These systems for delivering both developer fluid and deionized water or other material can reduce the impact force of dispensed liquid(s) thus preventing pattern collapse which may otherwise cause significant yield management problems for applications calling for small feature sizes. Furthermore, the delivery systems herein may be incorporated into or reside in the developer fluid module of a wafer track system in which uniform laminar air flow field exists as a prerequisite. In this application, the invention can be classified as involving several concepts including: (1) a multi-port
ASML Holdings N.V.
Lorengo J. A.
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