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Nitrogen Enhanced Selectivity of Debris (Carbon-Rich Material) Versus Polyimide

IP.com Disclosure Number: IPCOM000040617D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Schwartz, GS: AUTHOR [+2]

Abstract

The introduction of nitrogen to a plasma etching environment increases the selectivity of the etching process. The method is described in the following. An excimer laser is used to etch vias and lands on a metallized ceramic polyimide (MCP) surface. The laser beam is patterned through a mask and ablates the polyimide in the desired areas. The ablated material is removed to the polyimide surface, as shown in the drawing. The debris is a carbon-rich substance. A pure oxygen (O2) plasma removes the debris with high selectivity. Selectivity (S) is defined as S = etch rate of debris/etch rate of polyimide. This implies that the etching mechanism of the debris is more strongly oxygen dependent than the etching of the polyimide. Although the selectivity in a pure oxygen plasma is high, the actual etch rate of the debris is slow.

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Nitrogen Enhanced Selectivity of Debris (Carbon-Rich Material) Versus Polyimide

The introduction of nitrogen to a plasma etching environment increases the selectivity of the etching process. The method is described in the following. An excimer laser is used to etch vias and lands on a metallized ceramic polyimide (MCP) surface. The laser beam is patterned through a mask and ablates the polyimide in the desired areas. The ablated material is removed to the polyimide surface, as shown in the drawing. The debris is a carbon-rich substance. A pure oxygen (O2) plasma removes the debris with high selectivity. Selectivity (S) is defined as S = etch rate of debris/etch rate of polyimide. This implies that the etching mechanism of the debris is more strongly oxygen dependent than the etching of the polyimide. Although the selectivity in a pure oxygen plasma is high, the actual etch rate of the debris is slow. This is due to a lack of atomic oxygen formed in a pure oxygen plasma. The addition of small quantities of carbon tetrafluoride (CF4 to a pure oxygen plasma increases the etch rate of the debris. This is due to the increase of atomic oxygen caused by the CF4 addition. A side effect, however, of the CF4 addition is increased etching of the polyimide. This is caused by the presence of more atomic oxygen and fluorine in the plasma, both of which participate in the polyimide etching. Hence, the etch rate of the debris is increased with the CF4 addition, but the selectivi...