John C. Sardella

Sub-half-micron i-line photolithography process using AZ BARLi

A process using a bottom-side antireflective coating, AZ BARLi, has been studied for 0.50 micrometers and sub-0.5 micrometers features using I-line photolithography. Significant improvements were demonstrated for such process parameters as CD swing curve ratio, exposure latitude, and reflective notching of the photoresist. Extensive characterization was done on defects observed between the BARLi and photoresist coatings, and a process developed for their elimination. Factors which had significant effects on the observed number of defects, and their distribution, were the type of photoresist coat program used, solvent treatment of the BARLi surface, and a high temperature bake after photoresist coat. Data is presented for a complete process, which includes plasma etching the BARLi antireflective coating.

Effects of absorptive dye loading and substrate reflectivity on a 0.5-micron i-line photoresists process

The effects of an increasing amount of absorptive dye contained in a positive i-line photoresist were studied for a 0.5 micrometers process on two substrates with substantially different reflectivities. Parameters such as dissolution rates, focus latitudes, and resistance to reflective notching were simulated and compared to experimental results. Reductions in resist profile and focus latitude were observed as the photoresist non-bleachable absorbance was increased, and as the substrate reflectivity was decreased. It was also found that a reduction in substrate reflectivity was more effective than increasing the resist dye loading in suppressing reflective notching of the photoresist.

Characterization and performance of advanced i-line photoresists for 0.5-micron CMOS technology

ABSTRACT An evaluation procedure for advanced I-line photoresists is presented. The evaluation is compre-hensive in nature, including manufacturing and quality requirements as well as the usual patterningperformance tests. The evaluation is divided into three general categories: Performance, Manufac- turability, and Materials. These categories include a total of 23 individual performance tests and 15 evaluation criteria. A scoring method is described which assigns a numerical rating to the resistperformance. Weighting constants contained in this procedure can be adjusted to vary the emphasison particular measures of the photoresist performance. 1. INTRODUCTION The use of I-line illumination systems for production of devices with a critical dimension of <0.5zm is assured as the immediate future of the semiconductor industry. However, if one examines thegeneral equation relating the minimum feature size to wavelength and numerical aperture (NA):Minimum Feature = k1 * it is clear that a k1 factor of <0.7 is required for numerical apertures of 0.5 or less. A k1 factor of 0.8is often assumed for production systems. Key to the development of production-worthy systems arematerial and process improvements which make the use of a k1 factor of less than 0.7 more appropriate.Recent papers comparing photoresists typically concentrate on the patterning performance of theindividual resists.13 While this is a primary concern, it does not take into account factors which areimportant in a manufacturing environment. It is clear that if two photoresists have comparable resolu-tion and process latitudes, but one is 30% faster, the faster photoresist is preferred for manufacturing.Thus, a photoresist selection process should include additional criteria.We have developed a photoresist/developer evaluation procedure which combines the usual mea-sures of photoresist performance with two additional evaluation categories: Manufacturability andMaterials. In the following sections we describe the objectives and the structure of each of the cate-gories and discuss the quantitative scoring procedure for the evaluation.