The effects of etch chemistry on the etch rates of ArF BARC products

Abstract

As the feature sizes of integrated circuits shrink, highly anisotropic etching process (i.e., ion-assisted plasma etch, or reactive ion etch (RIE)), becomes even more essential for successful pattern transfer in the fabrication of semiconductor devices. The stringent 193 nm lithography process necessitates the use of bottom anti-reflective coating (BARC) for controlling reflections and improving swing ratios. Prior to RIE of a patterned wafer, the BARC layer must first be opened to allow pattern transfer from the resist mask to the underlying films. As we enter the era of sub-90nm imaging, minimum loss of the photoresist during the BARC open step is becoming more critical, since the demand for higher optical resolution dictates the use of ever thinner resist films. This in turn requires higher etch rate of BARC materials.In this paper we report on the impact of etching gas chemistries on the etch rates of BARC materials. The correlation between the etch chemistry and BARC products will be discussed. Reactive ion etch rates for blanket BARC coatings and BARCs under resist patterns were measured. Etch rates of BARC products of various material compositions were measured with a typical ArF resist as reference. It is well known that the chemical composition and structure of organic materials essentially determine the etch rates under certain etch process conditions. The correlations between etch rates and BARC polymer chemistry are reported. Etch chemistries, (i.e. the chemical interaction of plasma reactive ions with BARC materials), may also have profound effects on etch rates. Here we report on results obtained using four etching gas chemistries to study how oxygen contents, polymerizing gases, and inert gas effect the etch rates of different ArF BARC products.

Etching spin-on trilayer masks

“…High etch rate organic BARCs were determined to etch 51% to 74% slower in patterned wafers using CF4/O2 gas mixtures. 8 On the other hand, under O2 etch conditions carbon underlayers beneath patterned Si-BARCs are found to etch significantly faster on patterned wafers than on blanket coatings of underlayers. The availability of oxygen radicals is presumably higher since only a portion of the underlayer is exposed to the oxygen radicals and the Si-BARC surface becomes inert once oxide formation is established.…”

Assessment Of Cl 2 /CHF 3 Mixture For Plasma Etching Process On Barc And Tin Layer For 0.21 µm Metal Line: Silterra Case Study

“…The very fundamental requirement in plasma etching method adopted in fabricating of an IC pattern is the photoresist remaining margin. The pre-defined photoresist pattern on the metal substrate during photolithography process comes together with the organic backside antirefractive coating film to improve reflection control and light absorption during photolithography (Boumerzoug, 2014;Huang & Weigand, 2008;Zhuang et al, 2006). BARC layer minimizes thin film interference effects by reducing reflected light.…”