This paper discusses a novel approach of using a developer-soluble gap fill material, wherein the gap fill material is coated in a layer thick enough to planarize all the topography and is then recessed using a standard 0.26N TMAH developer. The material recess process takes place in the same coater track where it is coated and therefore simplifies the process and increases wafer throughput. Performance and properties of two types of developer-soluble gap fill materials (EXP03049 and NCA2528) based on two different polymer platforms will be discussed in detail.
The need for constant reduction in critical dimensions (CD) of integrated circuits to make them faster has been the driving force for next generation lithography. Currently KrF (248nm) is the shortest wavelength of light being used by IC manufacturers to mass produce devices. If the semiconductor industry continues at the same pace of packing more information on a chip, shorter wavelength (193nm) (ArF Excimer laser) will soon be introduced in production. Shorter wavelengths mean larger swing ratios, CD variations, reflective notching and standing waves due to sharp increase in reflectivity. Therefore some mechanism to reduce reflectivity becomes increasingly important at shorter wavelengths. Bottom antireflective coatings (BARCs) will play an important role in this endeavor. This paper discusses the chemistry and performance of two new spin-on organic 193nm BARCs (ARC 27 and ARC 28) optimized for their use at 1st reflectivity minimum thickness (30-40nm). The optical values of ARC 27 (n= 1.7, k= 0.56) measured by ellipsometer at 193nm give 0% reflectivity at the 1st reflectivity minimum with the optimum thickness of the BARC being 30nm. Lithographic studies with 193nm photoresist show good performance down to 90nm with isolated line (PAR705) and 100nm with dense line photoresist (PAR710,718). The optical properties of ARC 28 are 1.53 and 0.54 and a nominal thickness of 40nm on silicon is recommended to achieve 0% reflectivity. It shows good resolution at 110nm L/S and broad photoresist compatibility.
The list of desired properties for a spin-on 193-nm BARC steadily increases. In response, crosslinkable polymers from different chemical families than the conventional acrylics and vinyls are being studied for applicability in preparing improved thermosetting BARCs. Alternate polymer platforms discussed in this paper include polyethers, polyesters, polyurethanes, and polysaccharides. A BARC that uses a blend or mixture of commercially-available polymers for the binder is highlighted and the product's performance is described. The BARC parameters that are discussed include film properties, flash point, optical data and reflectivity, solution and spin-bowl compatibility, plasma etching rate, resist profile, conformality, and metals content. Based on the test results outlined in this paper, the polymer blend BARC JM2218-56 is expected to advance towards commercialization.
Two organic, spin-on BARCs are in the small scale manufacturing phase -- with the goal being a 193-nm product optimized for commercialization. Chemistries of the BARCs are shown in this paper and performance of the two products relative to industry accepted needs is discussed. The thermoset BARCs, EXP98090B and EXP99001D, are prepared from hydroxy-functional, dye-attached acrylic polymers by adding an aminoplast and sulfonic acid catalyst. With select 193-nm resists, the BARCs give resolution of L/S pairs down to 0.12 micrometer. Plasma etch rates of both BARCs are comparable to those of 193-nm photoresists. Other BARC performance parameters that are discussed for the two products include: film and optical properties, conformality, simulated reflectance curves, spin-bowl compatibility, metals content, and defects.
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