The transfer of photoresist LER through etch

Adam R. Pawloski; Alden Acheta; Scott Bell; Bruno La Fontaine; Tom Wallow; Harry J. Levinson

doi:10.1117/12.652206

29 March 2006 The transfer of photoresist LER through etch

Adam R. Pawloski, Alden Acheta, Scott Bell, Bruno La Fontaine, Tom Wallow, Harry J. Levinson

Proceedings Volume 6153, Advances in Resist Technology and Processing XXIII; 615318 (2006) https://doi.org/10.1117/12.652206
Event: SPIE 31st International Symposium on Advanced Lithography, 2006, San Jose, California, United States

Abstract

A method is presented to determine a transfer function for line edge roughness (LER) from the photoresist pattern through the etch process into the underlying material, such as a polysilicon gate. The image fading technique was employed to determine the dependence of photoresist LER on the image-log-slope (ILS) of the aerial image. From this initial condition in resist, LER after the etch process was measured in polysilicon and related to the ILS used to pattern the resist. From these two relationships, a transfer function could be derived to quantify the magnitude of LER that transfers into the polysilicon under layer from the photoresist. A gate layer type film stack and a 193nm resist system were employed. Results demonstrated that photoresist LER did transfer through the etch process. Increasing the resist LER increased the post-etch LER in polysilicon, and accordingly, minimizing resist LER minimized polysilicon LER. The etch process can reduce the magnitude of roughness in polysilicon over a range of mid and low spatial frequencies, however the extent of the roughness reduction diminishes as the resist LER reaches its minimum at large values of the ILS. In addition, resist trim rates during etch were apparently increased when LER of the resist was large. These results demonstrate that post-etch LER in polysilicon may be limited by the minimum LER achievable in resist, despite the occurrence of apparent smoothing mechanisms through the etch process.

Citation Download Citation

Adam R. Pawloski, Alden Acheta, Scott Bell, Bruno La Fontaine, Tom Wallow, and Harry J. Levinson "The transfer of photoresist LER through etch", Proc. SPIE 6153, Advances in Resist Technology and Processing XXIII, 615318 (29 March 2006); https://doi.org/10.1117/12.652206

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