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.
We report about the development of novel nanocomposite resists that incorporate colloidal silica nanoparticles into
conventional resist materials to yield thick coatings with both excellent lithographic properties and significantly
increased plasma etch resistance. 10-50 wt% silica nanoparticles of 10-15 nm in size were dispersed homogeneously in a
variety of standard resist resins by a simple process. The nanocomposite resists have similar lithographic performances
to conventional resists without silica nanoparticles. The nanocomposite resists also show excellent process window
capability and stability. Oxygen plasma etch and deep reactive ion etching (DRIE) processes were used to evaluate the
etch resistance of the nanocomposite resists. Compared with standard photoresists, the oxygen plasma etch rate is
reduced by 38-80% when the silica content increases from 20 to 50 wt%. The etch selectivity of nanocomposite resists
with 40 wt% silica is increased by 70% in DRIE test.
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.
As information densities increase with each generation of microchips, there is a concurrent reduction in feature sizes and even chip dimensions. With reduced chip sizes, the horizontal space for connectors on the back side of the chips is also limited. Most resists are not thick enough to accommodate the height of the connector posts needed. As a consequence, the plated posts or “bumps” overfill the imaged via holes thereby providing a mushroom effect that reduces usable horizontal space for other connectors. We have formulated a high solids photoresist (AZ 50 XT) capable of depositing 60-90μm single coat resist films. By optimizing processing conditions, reasonably straight side-wall geometries are possible. The importance of processing parameters (baking, exposure and development) are heightened by the inherent difficulty in balancing residual solvent against reasonable processing times needed for commercial use. This paper summarizes a joint program between Clariant and SUSS Microtec in optimizing the use of AZ 50 XT resist for bumping layer applications.