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Flow through furnace to eliminate batching,shorten cycle time, and provide better factory integration Disclosure Number: IPCOM000004616D
Original Publication Date: 2001-Feb-28
Included in the Prior Art Database: 2001-Feb-28
Document File: 3 page(s) / 29K

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Tim Stanley: AUTHOR [+3]


Flow through furnace to eliminate batching,shorten cycle time, and provide better factory integration

This text was extracted from a Microsoft Word 97 document.
This is the abbreviated version, containing approximately 95% of the total text.

Problem Summary

Batch furnace steps drive the extended cycle time of semiconductor factories. The time to build and disassemble production batches more than double overall processing times. They are also a major source of variability in the production process, reducing the predictability of output and causing cycle times to increase and output capacity to be reduced. Because of the furnace production batch requirements, furnaces can not be integrated directly with lot based or single wafer process tools.

Solution Summary

A flow through furnace would allow wafers to start processing as soon as they arrive at the tool. This would reduce problems with maintaining optimal surface state on the wafers just before processing due to wait time. It would allow for direct integration with other lot and single wafer based tools. Cycle time and factory integration with this type of system would result in improved cost structure.

Wafers flow one at a time into the controlled environment of the furnace and exiting at another location one wafer at a time, with the total time between entrance and exit being dictated by the physical requirements of the process.

Many wafers may be simultaneously in the furnace to provide cost effective throughput.

These concepts are envisioned for both atmospheric and low-pressure furnace systems.

Prior Art:

Watkins Johnson has built metal belt furnaces for relatively low temperature atmospheric deposition. Bakeries often use a flow through furnace but without the cleanliness required for a microelectronics application. Bolgett also builds a similar type of ovens for Pizza Hut.

Past art has focused on large batch furnaces or single wafer reactors. These have been driven by cost of ownership concerns. For example, Watkins-Johnson flow through furnaces are limited to low temperature (600 C), atmospheric reactors with limited cleanliness and metal contaminates because a metal belt carries the wafers.

Ideas for flow through Furnaces:

As illustrated in FIG. 1 a flow through furnace provides a solution to a problem that plagues the microelectronic industry, namely, the efficient integration of processes that take an extended period of time. One embodiment of this idea illustrated at the left consists of a large quartz tube with a quartz "Pater Noster" device that carries the wafers slowly up one side of the tube and down on the opposite side. The wafers would enter through a narrow door slit on one side and be retrieved on the opposite side.

In an alternate embodiment illustrated in FIG. 2, wafers would travel in quartz chambers inside of a heated tunnel. The wafers would enter the tunnel on one end and travel to an exit port. Choice of exit port determines processing time. The chemical species for processing could come from individually supplied (refreshed) solid sources or in gaseous form through ports in the tunnel. Gas only flows when chamber is in use. The tunnel could be very long utilizing for example space around the fab building. The boats ...