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Plasma-Induced Hardening of Photoresists - Various Gases

IP.com Disclosure Number: IPCOM000041277D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Johnson, C: AUTHOR [+2]

Abstract

It has previously been reported that treating photoresist in plasma systems using oxygen and CF4, respectively, hardens the resist such that, coupled with a subsequent high temperature bake, the resist is stabilized for ion implantation and for reactive ion etching. It has been found that the following gases are effective agents for performing hardening of photoresists: argon, helium, CHF3, CCl2F2, C2F6, C3F8, neon, SF6 and hydrogen. Various mixtures of these gases should also be effective in producing hardening. For hardening, CF4+H2 and Cl+Ar have been found to be effective. The results achieved were replicated using resists, such as Shipley AZ 1350J resist. The primary difference between these two techniques is the shape of the resist pattern following the post bake.

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Plasma-Induced Hardening of Photoresists - Various Gases

It has previously been reported that treating photoresist in plasma systems using oxygen and CF4, respectively, hardens the resist such that, coupled with a subsequent high temperature bake, the resist is stabilized for ion implantation and for reactive ion etching. It has been found that the following gases are effective agents for performing hardening of photoresists: argon, helium, CHF3, CCl2F2, C2F6, C3F8, neon, SF6 and hydrogen. Various mixtures of these gases should also be effective in producing hardening. For hardening, CF4+H2 and Cl+Ar have been found to be effective. The results achieved were replicated using resists, such as Shipley AZ 1350J resist. The primary difference between these two techniques is the shape of the resist pattern following the post bake. The 02 hardened samples in the plasma system exhibit a "bread loaf" shape, while the CF4 samples appear wrinkled, but in both cases no edge movement of the resist is apparent following the post bake. Experiments directed toward the extendibility of plasma hardening to a diode-configured system were undertaken. The initial system chosen was the Cooke single wafer system due to its availability and flexibility for gas species variation. All gases utilized in the Cooke diode system resulted in resist hardening similar to that reported before. With the exception of C2F6 and LFE DE100, all samples exhibited a wrinkled surface following post bake in an oven. The samples treated with C2F6 and DE100 exhibited wrinkled surfaces on resist patterned to a small dimension. In no case, however, was there flow of the resist edge. Subsequent to the initial oven bake, control samples were baked on a plate in an oven at 210OEC and bread loafing was observed on the same samples on which they had initially been observed with the small geometries. In addition, the samples treated in CCl2F8 and SF6, which had wrinkled during the oven bake, exhibited bread loafing on the larger geometries. The samples treated in CF4, argon, helium, and CHF3 continued to produce wrinkled surfaces irrespective of the bake conditions. It is well known that gases rich in oxygen or chlorine tend to etch photoresist at a higher rate than do gases in which the active species are primarily fluorine radicals. In the light of the above, and based on an intuitive feeling that the hardening phenomena was a surface and not a bulk mechanism, experiments were next conducted in a pure 02 ambient plasma hardening. Oxygen plasma hardening was performed in the system at two different sets of parameters for varying lengths of time. The first set of parameters was for a high etch rate of the resist, 1600 ~/min at 200 watts, 50 m of pressure, with a flow rate of 40 cc/min. The second set of parameters was for a low resist etch rate, 700...