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Sidewall Angle Reduction of Silicon Oxide Features on Semiconductor Wafers

IP.com Disclosure Number: IPCOM000037568D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gut, GM: AUTHOR [+3]

Abstract

The procedure described herein is performed to reduce the sidewall angle of silicon oxide-covered polysilicon lines on a semiconductor chip. The polysilicon lines are initially formed with a vertical sidewall. The oxide which is deposited on the sidewall is conformal. Therefore, the steep sidewall angle is retained. The sidewall may have other undesirable features in addition to its steepness.

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Sidewall Angle Reduction of Silicon Oxide Features on Semiconductor Wafers

The procedure described herein is performed to reduce the sidewall angle of silicon oxide-covered polysilicon lines on a semiconductor chip. The polysilicon lines are initially formed with a vertical sidewall. The oxide which is deposited on the sidewall is conformal. Therefore, the steep sidewall angle is retained. The sidewall may have other undesirable features in addition to its steepness.

Fig. 1 shows the profile of the polysilicon lines and the profile after coating with the first silicon oxide layer. The first step of the sidewall angle reduction process calls for the reactive ion etching of the oxide to remove about 70% of its initial thickness. The RIE step uses CF4 as the etch gas and relatively high power during the etch. The process attacks corners of features and horizontal features on the wafers preferentially and results in an etched profile approximately as depicted in Fig. 2.

A second layer of silicon oxide is then deposited on the wafers to restore the original oxide thickness. This oxide layer is deposited conformally as well, resulting in the retention of the reduced sidewall angle which was just generated.

At this point, the reduced sidewall angle features are easy to cover with metal conductive lines with little possibility of breakage of these lines over very steep sidewalls.

Disclosed anonymously.

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