Two fundamentally different approaches for chemical ArF resist shrinkage are evaluated and integrated into process flows for 90 nm technology node. The chemical shrin k and the corresponding gain in process window is studied in detail for different resist types with respect to CD uniformity through pitch, linearity and resist profiles. For both, SAFIER and RELACS material, the sensitivity of the shrink process with respect to the baking temperature is characterized by a temperature matrix to check process stability, and optimized conditions are found offering an acceptable amount of shrinkage at contact and trench levels. For the SAFIER material, thermal flow contributes to the chemical shrink which is a function of the photoresist chemistry and its hydrodynamic properties depending on the resists' glass transition temperature (Tg) and the baking temperature: at baking temperatures close to Tg, a proximity and pattern dependent shrink is observed. For a given resist, line-space patterns and contact holes shrink differently, and their resist profiles are affected significantly. Additionally, the chemical shrinkage depends on the size of contact holes and resist profile prior to the application of the SAFIER process. At baking temperatures below Tg some resists exhibit no shrink at all. The RELACS technique offers a constant shrink for contacts at various pitches and sizes. This shrink can be moderately adjusted and controlled by varying the mixing bake temperature which is generally and preferably below the glass transistion temperature of the resist, therefore no resist profile degradation is observed. A manufacturable process with a shrink of 20nm using RELACS at the contact layer is demonstrated. Utilizing an increased reticle bias in combination with an increased CD target prior to the chemical shrink, the common lithography process window at contact layer was increased by 0.15um. The results also indicate a possibility for an extension of the shrink to greater than 50nm for more advanced processes.
The gear honing is the most economical way for hard finishing an involute helical gear after hobbing and heat treatment or after shaving and heat treatment. The gear honing can also be applied to the modification of gear tooth surfaces to compensate for the distortions that occur during heat treatment process. Most published papers on the technology of gear honing describes on the principle of generated gear surface. However, the longitudinal tooth flank crowning of a helical gear with honing has not been investigated yet. Therefore, in this paper, we proposed a novel method for longitudinal tooth flank crowning of work gear surfaces by setting a crossed angle between the honing cutter and work gear axes as a linear function of honing cutter's traverse feed in the honing process. A mathematical model for the tooth profile of work gear honed by a standard honing cutter is also established. Three numeral examples are presented to illustrate and verify the merits of the proposed gear honing method in longitudinal crowning.
Planarization of gap-filling materials for low-k dual damascene processes is getting more and more important due to the photoresist process window shrinking as the pitch and critical dimensions shrink. Defects, especially pattern collapses, will become a serious problem if there is no global planarization for low-k dual damascene processes. IC manufacturers and materials vendors have proposed several ways to improve the global planarization of gap filling, such as using materials with different viscosities, fine tuning gap-filling material coating recipes, and even using optical or chemical treatments to obtain global planarization. The effect of the different conformalities of the first and second coating materials on coating performance will be discussed.
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