1. Field of the Invention
The present invention is related to multiple sources that can be used in, for example, lithographic systems.
2. Related Art
The manufacture of a liquid crystal display, or a flat panel display (FPD) involves a manufacturing process that is similar to that used in the integrated circuit (IC) industry that produces computer chips. An exposure system is used to project an image of a circuit pattern so as to expose a photo resist coated substrate. The actual circuit is created after the exposed substrate is processed using standard microlithographic processes. Depending on the particular FPD design, this exposure process may be repeated many times on one substrate for different layers to implement the circuit design. When all the exposures and microlithographic processing steps have been completed so the desired circuit pattern has been created, the substrate is integrated with other components to create a flat panel display screen.
Although FPDs have been in production since the late 1980s, the current size requirement is for FPDs of up to 42 inches diagonal, with 54 and 60 inches diagonal under development. (Note that in the United States, screen dimensions are usually specified using the English system, while optical design and tool dimensioning is usually done in metric.)
Having sources that output sufficient power for exposure is generally an issue of concern in lithographic systems, and is particularly of concern in lithographic systems that are used for FPD exposure. With modem FPDs having dimensions up to sixty inches diagonal (and even larger in the future), and with exposure areas increasing due to a desire to maximize overall FPD manufacturing throughput, electromagnetic radiation sources that output a very large amount of power are required. For example, FPD exposure systems under current consideration may require as much as 250 watts of power output, to expose relatively large FPDs. Lasers are typically used as sources for this purpose. However, lasers that produce outputs in the hundreds of watts are either unavailable, or extremely expensive. For example, lasers that are relatively easily available commercially typically range in the 10 to 25 watts of output. Furthermore, the cost of a laser system does not scale linearly with an increase in its power output, but tends to increase exponentially.
Accordingly, there is a need in the art for exposure systems that are relatively inexpensive and provide a large power output.