| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS-MoM |
| Session: | Current Challenges of Plasma Etching Technologies |
| Presenter: | Nathan Marchack, IBM T.J. Watson Research Center |
| Authors: | N.P. Marchack, IBM T.J. Watson Research Center S.U. Engelmann, IBM T.J. Watson Research Center E.A. Joseph, IBM T.J. Watson Research Center R.L. Bruce, IBM T.J. Watson Research Center H. Miyazoe, IBM T.J. Watson Research Center E.M. Sikorski, IBM T.J. Watson Research Center T. Suzuki, ZEON Chemicals L.P. M. Nakamura, ZEON Chemicals L.P. A. Itou, Zeon Corporation H. Matsumoto, Zeon Corporation |
| Correspondent: | Click to Email |
As critical dimensions and pitch sizes of integrated circuit technologies continue to decrease, the challenges associated with maintaining pattern transfer fidelity become especially difficult to surmount. LER/LWR, CD variation, iso/dense feature loading and deformation of the organic soft masks are commonly observed phenomena. Other issues include extensive plasma damage or mask retention for post-lithography solutions.1
Our team recently introduced a new etch gas which is able to etch nitride by selective deposition of a fluorocarbon layer2, analogous to the well established oxide etch mechanism commonly used in manufacturing.3 Selective deposition was achieved by redesigning the FC etch gas, where reaction with a nitride substrate layer reduces the FC film thickness compared to silicon or oxide substrates. Owing to the complex, distinct nature of the reaction pathways offered by this new plasma chemistry, optimizing the etch performance involves tuning plasma parameters that have not been traditionally investigated. We have evaluated the influence of substrate and showerhead temperatures, gas admixture chemistry and plasma pulsing on the performance of this etch gas for hard mark patterning applications.
By tuning the chemical admixture of the plasma, 50nm pitch patterning of an 80nm thick nitride hard mask layer using a 65nm carbon mask was achieved with greatly reduced LER/LWR (~2.3/2/7) and minimal iso/dense feature loading compared to a traditional CF4/CHF3 mixture (LER/LWR ~5/8). The use of plasma pulsing, as well as lowering the lid temperature, was found to increase the carbon mask retention while maintaining reduced LER/LWR. The effect of lid temperature was shown to be related to gas dissociation, which was observed through full spectrum OES spectra collected. The improved mask retention under these conditions allowed for LER/LWR to be reduced even further by reducing the aspect ratio of the structures.