Xinpeng Wang

Etch Arts of Dual Damascus Structure and Their Impacts on WAT/VBD in 65nm Cu Interconnects

In this paper, based on the via-first DD technology, we focus on the profile tuning of via and trench and the liner removal in order to optimize the trench profile. Via profile tuning include how to realize the via with the bowling profile, vertical profile and tapering profile. Trench profile tuning emphasizes the formation mechanism of bowling profile and top rounding profile. Footing profile and under-cutting profile of via bottom in liner open step is also addressed. The effect of different etching profiles on Rc, VBD (Breakdown Voltage) are examined. Results show that different via profiles have no impact on Rc, top-rounding trench-profile results in worse VBD, while under-cut & footing liner would deliver lower and higher Rc, respectively.

Mechanism of via etch striation and its impact on contact resistance & breakdown voltage in 65nm cu low-k interconnects

The mechanism of two kinds of via etch striation (type I and type II) has been investigated to improve contact resistance (Rc) uniformity and solve breakdown voltage (VBD) issue in 65 nm Cu low-k interconnects. Heavy etching polymer deposition on the sidewall of capping layer and rapid photo-resist (PR) consumption on PR shoulder are two main resources to result in via etch striation. The effects of both via etch striations on Rc and VBD can be decoupled. Type I striation related to barc open (BO) step leads to worse Rc uniformity while type II striation formed in main etch (ME) and over-etch (OE) step degrades VBD performance.