Photography – Fluid-treating apparatus – Heating – cooling – or temperature detecting
Reexamination Certificate
1999-10-05
2001-03-06
Rutledge, D. (Department: 2851)
Photography
Fluid-treating apparatus
Heating, cooling, or temperature detecting
C396S578000, C396S611000
Reexamination Certificate
active
06196734
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to semiconductor processing, and in particular to a system for regulating developer temperature.
BACKGROUND OF THE INVENTION
In the semiconductor industry, there is a continuing trend toward higher device densities. To achieve these high densities there has been and continues to be efforts toward scaling down device dimensions (e.g., at submicron levels) on semiconductor wafers. In order to accomplish such high device packing density, smaller and smaller features sizes are required. This may include the width and spacing of interconnecting lines, spacing and diameter of contact holes, and the surface geometry such as corners and edges of various features.
The requirement of small features with close spacing between adjacent features requires high resolution photolithographic processes. In general, lithography refers to processes for pattern transfer between various media. It is a technique used for integrated circuit fabrication in which a silicon slice, the wafer, is coated uniformly with a radiation-sensitive film, the resist, and an exposing source (such as optical light, x-rays, or an electron beam) illuminates selected areas of the surface through an intervening master template, the mask, for a particular pattern. The lithographic coating is generally a radiation-sensitive coating suitable for receiving a projected image of the subject pattern. Once the image is projected, it is indelibly formed in the coating. The projected image may be either a negative or a positive image of the subject pattern. Exposure of the coating through a photomask causes the image area to become either more or less soluble (depending on the coating) in a particular solvent developer. The more soluble areas are removed in the developing process to leave the pattern image in the coating as less soluble polymer.
Due to the extremely fine patterns which are exposed on the photoresist, application and maintaining a desired temperature of the developer are significant factors in achieving desired critical dimensions. The developer should be maintained at a uniform temperature in order to insure uniformity and quality of the underlying photoresist layer to be developed. Small changes in the time/temperature history of the developer can substantially alter image sizes, resulting in lack of image line control—a few degrees in temperature difference may drastically effect critical dimensions. For example, often substantial line size deviations occur when the developer temperature is not maintained within 0.5 degree tolerance across a silicon wafer.
An efficient system/method to maintain developer temperature is therefore desired to increase fidelity in image transfer.
SUMMARY OF THE INVENTION
The present invention provides for a system which facilitates controlling developer temperature. A preferred embodiment of the system employs a plurality of optical fibers arranged to project radiation on respective portions of the developer. The radiation reflected from the developer is indicative of at least one of several parameters of the developer (e.g., thickness, color and absorption) which vary in correlation with developer temperature. A plurality of heaters are arranged to each correspond to a particular developer portion, respectively—each heater is responsible for heating the particular developer portion. The developer temperature is monitored by the system, and the heaters are selectively driven by the system so as to maintain developer temperature at a desired level. As a result, substantial uniformity in developer temperature is achieved, which in turn increases fidelity of image transfer.
One particular aspect of the invention relates to a system for regulating developer temperature. At least one lamp operates to heat a portion of a developer, and a lamp driving system drives the at least one lamp. A system for directing radiation directs radiation to the portion of the developer, and a measuring system measures parameters of the developer based on radiation reflected from the developer. A processor is operatively coupled to the measuring system and a lamp driving system, the processor receives developer parameter data from the measuring system and the processor uses the data to at least partially base control of the at least one lamp so as to regulate temperature of the at least a portion of the developer.
Yet another aspect of the present invention relates to a method for regulating developer temperature, comprising the steps of defining a developer as a plurality of portions; directing radiation onto at least one of the portions; collecting radiation reflected from the at least one portion; analyzing the reflected radiation to determine the temperature of the at least one portion; and controlling a heating device to regulate the temperature of the at least one portion.
Still another aspect of the present invention relates to a method for regulating temperature of a developer, comprising the steps of: partitioning the developer into a plurality of grid blocks; using a plurality of heaters to heat the developer, each heater functionally corresponding to a respective grid block; determining temperatures of portions of the developer, each portion corresponding to a respective grid block; and using a processor to coordinate control of the heaters, respectively, in accordance with determined temperatures of the respective portions of the developer.
Another aspect of the present invention relates to a system for regulating temperature of a developer including: means for sensing temperatures of a plurality of portions of the developer; means for heating the respective developer portions; and means for selectively controlling the means for heating so as to regulate temperature of the respective developer portions.
To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
REFERENCES:
patent: 4518848 (1985-05-01), Weber
patent: 4859572 (1989-08-01), Farid et al.
patent: 5167078 (1992-12-01), Bolde et al.
patent: 5716763 (1998-02-01), Benoit et al.
patent: 2-13958 (1990-01-01), None
patent: 3-259511 (1991-11-01), None
Rangarajan Bharath
Templeton Michael K.
Advanced Micro Devices
Amin, Eschweiler & Turocy, LLP
Rutledge D.
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