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  Apparatus and method for argon plasma induced ultraviolet light curing step for increasing silicon-containing photoresist selectivityUSPTO Application #: 20070072095Title: Apparatus and method for argon plasma induced ultraviolet light curing step for increasing silicon-containing photoresist selectivity Abstract: Provided is a method and apparatus for increasing an etching selectivity of photoresist material. An exemplary method initiates with providing a substrate with a developed photoresist layer. The developed photoresist layer on the substrate includes polymer chains containing silicon. Next, the substrate and developed photoresist layer are exposed to an ultraviolet (UV) light, where the UV light emanates from a UV generating agent. A portion of the developed photoresist layer is then converted to a hardened layer where the hardened layer is created by cross-linking the polymer chains containing silicon and the cross-linking is activated by the UV light. Next an etch may be performed on the substrate using the hardened layer. (end of abstract)
Agent: Martine Penilla & Gencarella, LLP - Sunnyvale, CA, US Inventors: Francis Ko, Richard Chen, Charlie Lee USPTO Applicaton #: 20070072095 - Class: 430005000 (USPTO) Related Patent Categories: Radiation Imagery Chemistry: Process, Composition, Or Product Thereof, Radiation Modifying Product Or Process Of Making, Radiation Mask The Patent Description & Claims data below is from USPTO Patent Application 20070072095. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional to copending prior U.S. patent application Ser. No. 09/894,230, filed Jun. 27, 2001, and entitled "APPARATUS AND METHOD FOR ARGON PLASMA INDUCED ULTRAVIOLET LIGHT CURING STEP OR INCREASING SILICON-CONTAINING PHOTORESIST SELECTIVITY." This application is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates generally to lithography and more particularly to a method and apparatus for increasing the selectivity of a silicon-containing photoresist layer to improve profile control of etched features without decreasing wafer throughput. [0004] 2. Description of the Related Art [0005] The ability to work selectively on small well defined areas of a substrate is paramount in the manufacture of semiconductor devices. In the continuing quest to achieve higher levels of performance and higher functional density of the semiconductor devices, the microelectronics industry is committed to applying new processes to further reduce the minimum feature sizes of the semiconductor devices. [0006] As the feature sizes are reduced, the devices can become smaller or remain the same size but become more densely packed. As such, advances in lithographic technologies used to pattern the semiconductor devices must keep pace with the progress to reduce feature sizes, in order to allow for smaller and more dense. For example, one of the main ways to reduce the device critical dimensions (CD) through lithographic technologies has been to continually reduce the wavelength of the radiation used to expose the photoresist. [0007] Sharp lithographic transmission becomes more of a challenge as wafers progress to higher density chips with shrinking geometries. Furthermore, as metallization transitions to dual damascene processes, lithography techniques to pattern holes or trenches in the dielectric become more critical. In particular, the photoresists employed in the lithographic techniques must provide for proper selectivity so that downstream etching processes yield sharp profiles. Moreover, as device features progressively become smaller, the aspect ratios for those same features become greater, thereby making it more difficult to accurately perform etching operations. [0008] Photoresists are typically polymeric materials consisting of multi-component formulations. Additionally, a photoresist may be applied as a single layer or as multiple layers where one of the layers contains silicon. Multi-layered photoresists tend to offer superior formation of a pattern, therefore, the multi-layered photoresists are desirable as semiconductor devices become smaller. However, resist compositions containing silicon, either in the main resist polymer or by post-exposure surface treatment (e.g., silylation), have either failed to deliver adequate improvement in etch resistance or have had poor processing performance due to the unacceptable selectivity past the silicon containing layer. [0009] As a result, there is a need to solve the problems of the prior art to improve the selectivity past the developed photoresist layer containing silicon, without simultaneously decreasing wafer throughput, so that during etching there is improved ability to distinguish between silicon containing photoresists and non silicon containing photoresists or the dielectric. SUMMARY OF THE INVENTION [0010] Broadly speaking, the present invention fills these needs by providing a photoresist layer that has been hardened to increase the selectivity of the hardened photoresist layer relative to an underlying photoresist or underlying dielectric. In addition, the hardening process may take place in an etch chamber so that the fabrication, e.g., etching steps, may be combined with treating processes to improve wafer throughput. It should be appreciated that the present invention can be implemented in numerous ways, including as an apparatus, a system, a device, or a method. Several inventive embodiments of the present invention are described below. [0011] In one embodiment, an apparatus for exposing a photoresist-developed substrate is provided. In this embodiment, a chamber is included where the chamber has at least one gas inlet adapted to introduce a gas into the chamber. Also included is a support within the chamber. A substrate on the support where the substrate has at least one developed photoresist layer is included. The substrate is exposed to an ultraviolet (UV) light within the chamber where the UV light is generated from a UV generating agent The exposure of the developed photoresist to the UV light causes at least a portion of the developed photoresist layer to transform to a hardened layer. [0012] In another embodiment of the invention an apparatus for curing a photoresist is provided. In this embodiment, a chamber having at least one gas inlet adapted for introducing an ultraviolet (UV) generating agent into the chamber and a support within the chamber are included. A substrate, on the support, where the substrate has a first photoresist layer and a second photoresist layer is included, where the first photoresist layer is disposed over the second photoresist layer. The first photoresist layer includes silicon containing polymer chains. The silicon containing polymer chains are cross-linked upon exposure to UV light to form a hardened layer at a top region of the first photoresist layer, where the UV light is generated by the UV generating agent. [0013] In yet another embodiment of the invention, a method for increasing a selectivity of a photoresist is provided. The method initiates with providing a substrate with a developed photoresist layer, the developed photoresist layer including polymer chains containing silicon. Next, the substrate is exposed to an ultraviolet (UV) light, where the UV light emanates from a UV generating agent. Finally, a portion of the developed photoresist layer is converted to a hardened layer where the hardened layer is created by cross-linking the polymer chains containing silicon, where the cross-linking is activated by UV light. [0014] In still another embodiment of the invention, a method for curing a photoresist is provided. The method initiates with providing a substrate with a first photoresist layer and a second photoresist layer. The first photoresist layer is developed and disposed over the second photoresist layer and the first photoresist layer is formulated to include polymer chains containing silicon. Next, the first photoresist layer is exposed to ultraviolet (UV) light where the UV light emanates from a UV generating agent. The method terminates after converting a portion of the first photoresist layer to a hardened layer where the hardened layer is configured to increase an etching selectivity ratio. [0015] In still yet another embodiment, a method for curing a photoresist disposed on a wafer in an etch chamber is provided. The method initiates with introducing an ultraviolet (UV) generating agent into an etch chamber through a process gas inlet of the etch chamber. The UV generating agent is induced to emit UV light. Next, the wafer is exposed to the UV light where the wafer has a developed photoresist layer formulated to include polymer chains containing silicon. Then, a portion of the developed photoresist layer is converted to a hardened layer upon exposure to the UV light. [0016] The advantages of the present invention are numerous. Most notably, the formation of the hardened layer increases the selectivity ratio of the underlying photoresist layer or interlayer dielectric relative to the hardened layer of the top photoresist layer. Accordingly, any etch processes performed on the substrate with the hardened layer will etch through the underlying photoresist layer or interlayer dielectric at an increased rate relative to the etch rate of the hardened layer. Furthermore, the etch profile control will be improved as a result of the increased selectivity, thereby allowing for pinpoint accuracy as semiconductor feature size continues to shrink. Additionally, an etch chamber may be utilized for curing the hardened layer. As a result, after the curing process, the substrate may be etched in the same chamber. Hence, throughput is increased and handling of the substrate is minimized. [0017] Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0018] The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, and like reference numerals designate like structural elements. [0019] FIG. 1 illustrates a block diagram displaying a substrate in which the top photoresist layer is being exposed prior to development in accordance with one embodiment of the invention. [0020] FIG. 2 illustrates block diagram depicting a developed substrate. Continue reading... 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