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Laser RIE Process for Etching of Organic Materials

IP.com Disclosure Number: IPCOM000042954D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Marks, RF: AUTHOR [+2]

Abstract

Reactive ion etching (RIE) can be used to remove organic materials, such as polyimide and photoresist. In this process, a plasma discharge is induced in a low pressure gas to produce highly reactive species, which then etch the organic material. An example is a mixture of CF4 and oxygen, which is used to etch polyimide. In order to replace the expensive plasma etching systems used for RIE processing, a CO2 laser is used to induce a plasma discharge in a mixture of oxygen and a fluorine- or chlorine-containing gas. Gases, such as SF6, CF2Cl2, C2F6 and CF4, have vibrational modes that can be exited by 10 mm radiation. For moderate energy densities, on the order of 4 J/cm2, multiphoton dissociation leads to the production of reactive species. For instance, SF6 + nhn T SF5* + F, C2F6 + nhn T CF3* + CF3*.

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Laser RIE Process for Etching of Organic Materials

Reactive ion etching (RIE) can be used to remove organic materials, such as polyimide and photoresist. In this process, a plasma discharge is induced in a low pressure gas to produce highly reactive species, which then etch the organic material. An example is a mixture of CF4 and oxygen, which is used to etch polyimide. In order to replace the expensive plasma etching systems used for RIE processing, a CO2 laser is used to induce a plasma discharge in a mixture of oxygen and a fluorine- or chlorine-containing gas. Gases, such as SF6, CF2Cl2, C2F6 and CF4, have vibrational modes that can be exited by 10 mm radiation. For moderate energy densities, on the order of 4 J/cm2, multiphoton dissociation leads to the production of reactive species. For instance, SF6 + nhn T SF5* + F, C2F6 + nhn T CF3* + CF3*. The excited molecular radicals and ions resulting from the dissociation have been shown to have rotational and vibrational energy distributions on the order of 1000 K. The oxygen molecules, while not direct absorbers of the IR radiation, will be excited by collisional energy transfer with excited radicals; i.e., X* + 02 T X + 02*. The excited oxygen is a strong oxidizing agent. It combines readily with carbon atoms to maintain a high ratio of fluorine- containing active species. The resulting mix of hot reactive species is then capable of etching organics in the same fashion as conventional RIE processing does. The c...