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Method for point-of-use means of supplying wafer fabrication cleanroom air with a low or reduced AMC level to the air in-take of process tools

IP.com Disclosure Number: IPCOM000020324D
Publication Date: 2003-Nov-12
Document File: 3 page(s) / 45K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for point-of-use means of supplying wafer fabrication cleanroom air with a low or reduced airborne molecular contamination (AMC) level to the air in-take of process tools. Benefits include improved functionality, improved performance, and improved yield.

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Method for point-of-use means of supplying wafer fabrication cleanroom air with a low or reduced AMC level to the air in-take of process tools

Disclosed is a method for point-of-use means of supplying wafer fabrication cleanroom air with a low or reduced airborne molecular contamination (AMC) level to the air in-take of process tools. Benefits include improved functionality, improved performance, and improved yield.

Background

         Semiconductor fabrication requires the control of contaminates within a cleanroom to maximize production yield. Common approaches to controlling odor and AMC levels within a cleanroom include the use of chemical filters on the make-up air handlers (MAHs) and/or recirculating air handlers (RAHs). While the use of chemical filters in the MAH enables the removal of AMCs from outside air, this approach does not address AMCs generated within the facility. Potential AMC sources within the facility include construction materials, process equipment (tools), and process chemicals.

Description

         The disclosed method is a means of supplying air with a low or reduced airborne molecular contamination concentration to individual fabrication machines. The potential requirement for a supply of low-AMC air is not limited to any individual functional area and sensitivity of the process to AMCs is expected to increase with each future process generation. The disclosed method includes the placement of chemical filters directly on top of the ultra low penetration air (ULPA) filters located in the ceiling grid immediately above the process machine. The AMC concentration in the supply air can be controlled to specified levels and ensure that the wafers being processed are not exposed to the contaminates in the cleanroom air (see Figure 1).

         The distance between the ceiling grid and the air in-takes for the mini-environment and the process area of the tool will determine if low AMC air can be supplied to the process tool solely by placement of chemical filters on the ceiling grid. For tools that have mini-environment or process area air intakes at greater distances from the ceiling grid, ducting or skirting from the ceiling grid to the vicinity of air in-take on the tool is required to ensure airborne contaminant levels are controlled to the specified limits. In cases where ducting to the air in-takes on the tool is not required, the extent of chemical filter coverage overhead is dependent on the distance between the ceiling grid and the air in-take.

         Application of the disclosed method is not limited to cleanroom designs with a pressure plenum directly above ceiling grid. The method can be applied to cleanroom designs where the space immediately upstream of the ULPA filters includes a fan-filter module-type air supply and a ducted air supply to the ULPA filters.

         Rapid expansion of the low-AMC air system as capacity requirements increase is more readily achievable with a point-of-use (POU) approach rather than a global approach to larger areas of...