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Browse Prior Art Database

New Way to Improve RIE Uniformity Using a Metal Pin

IP.com Disclosure Number: IPCOM000038749D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Dhong, SH: AUTHOR [+2]

Abstract

A new method of improving RIE uniformity is described herein providing for the installation of a metal pin at the center of a grounded electrode in a reactive ion etch (RIE) system. The etch rate of a typical RIE system shows a radial distribution. This effect is known as the "bull's eye" effect, and the wafers near the edge of the cathode etch faster than those near the center. (See Fig. 1.) The effect is primarily caused by the radial electric field distribution between the cathode and the opposing grounded electrode. Shaping the cathode to make the electric field distribution more radially uniform has been proposed. In this disclosure, a new and simpler way of improving the etch uniformity is described. The new method is shown in Fig. 2. A metal pin is placed at the center of the grounded electrode.

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New Way to Improve RIE Uniformity Using a Metal Pin

A new method of improving RIE uniformity is described herein providing for the installation of a metal pin at the center of a grounded electrode in a reactive ion etch (RIE) system. The etch rate of a typical RIE system shows a radial distribution. This effect is known as the "bull's eye" effect, and the wafers near the edge of the cathode etch faster than those near the center. (See Fig. 1.) The effect is primarily caused by the radial electric field distribution between the cathode and the opposing grounded electrode. Shaping the cathode to make the electric field distribution more radially uniform has been proposed. In this disclosure, a new and simpler way of improving the etch uniformity is described. The new method is shown in Fig. 2. A metal pin is placed at the center of the grounded electrode. The radial electric field distribution is modified such that the center of the wafer has higher electric fields than the edge. This makes the etch rate at the center increase relative to the edge and consequently the etch uniformity is improved. If necessary, a row of shorter metal pins can be placed to further improve the uniformity, as shown in Fig. 3. The new method is simpler than the previous method of shaping the cathode, which has to be machined each time a different configuration is tried. Shaping the cathode not only changes the electric field distribution but also affects the flow pattern of the etching...