Zhong Xiang

Organic ArF bottom anti-reflective coatings for immersion lithography

Substrate reflectivity control plays an important role in immersion lithography. Multilayer bottom anti-reflective coatings (B.A.R.C.s) become necessary. This paper will focus on the recent development in organic ArF B.A.R.C. for immersion lithography. Single layer low k ArF B.A.R.C.s in conjunction with multilayer CVD hard mask and dual layer organic ArF B.A.R.C. application will be discussed. High NA dry and wet lithography data will be presented. We will also present the etch rate data, defect data and out-gassing property of these new B.A.R.C. materials.

High-etch-rate low-bias bow outgassing BARC via-filling materials for 193-nm ArF lithographic process

As critical dimensions in integrated circuit (IC) device fabrication continue to shrink to less than 90 nm, designing multi-functional organic bottom anti-reflective coating (BARC) materials has become a challenge. In this paper, we report novel high performance BARC materials which are simultaneously capable of controlling reflectivity, planarizing on substrate surface, low bias filling without forming voids, low outgassing, high etch selectivity with resists and broad compatibility with resists. The new materials comprise of a chromophore that absorbs at 193 nm to give anti-reflective properties. By intriguing design of the crosslinking system to minimize the amount of low molecular weight additives and the by-product formation in the curing process, low-bias and low sublimation filling without formation of voids are achieved. In addition, the performance of the high etch rate BARC material can be further enhanced by blending with a low k high etch rate (~2.4X) material to achieve ultra high etch rate for ArF lithographic process. The filling properties, etch selectivity, lithographic and outgassing data of the new BARC materials will be presented.

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

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.