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Method for batch-cure temperature variation reduction by redirecting the convection airflow

IP.com Disclosure Number: IPCOM000016805D
Publication Date: 2003-Jul-16

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for batch-cure temperature variation reduction by redirecting the convection airflow. Benefits include improved reliability, improved functionality, and improved throughput.

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Method for batch-cure temperature variation reduction by redirecting the convection airflow

Disclosed is a method for batch-cure temperature variation reduction by redirecting the convection airflow. Benefits include improved reliability, improved functionality, and improved throughput.

Background

              The conventional supply and return walls on the wafer-processing oven are fabricated from a single sheet of 3/16” stainless steel (see Figure 1). The walls are placed in a punch press and holes fabricated across the entire surface. The wall designs do not take into consideration the effects they have on airflow concentrations as they relate to the high temperature cart and its position in the chamber. The punched-wall design enables the airflow to circulate through the chamber across the material handling system (MHS) cart. Because the entire wall has holes, the air not only passes through the cart where the product resides, the air passes around all sides of the cart, causing uneven heating. Additionally, the cart stop is positioned too far back in the chamber, enabling the thermal load to be off center in relationship to the airflow.

              The convection causes issues with respect to the thermal characteristics (such as ramp rate, peak, and dwell) across the product load (see Figure 2). Quadrant 3 does not receive the same amount of convection rate as the other locations in the magazine. As a result, the peak temperature, ramp rate, and dwell to be much lower than the target. The overall sigma is 1.17253, which is higher than the target.

General description

      The disclosed method is batch-cure temperature variation reduction by redirecting the convection airflow. The method improves the wafer-processing oven’s airflow supply/return system and load centering to better control the uniformity across the high-temperature MHS cart assembly.

              The key elements of the method include:

•             Redesign of the supply and return walls to concentrate the airflow across the MHS cart for better uniformity

•             Redesign of the oven cart stop by adding an additional plate on the bumper

•             Replacing the front door insert which protrudes outward ~2.5-inch to ~3/4-inch recessed insert

Advantages

              The disclosed method provides advantages, including:

•             Improved reliabi...