Eleazar Gonzalez

Method to measure ethylene oxide/propylene oxide surfactants in resist developers

Controlling the exact level of surfactants in resist developers is critical. Surfactant concentrations can influence parameters such as photospeed, resolution, and linearity. Too much or too little surfactant can have a significant impact on the performance of the developer. In our laboratory an analytical procedure was developed to quantitate an Ethylene Oxide/Propylene Oxide (EO/PO) surfactant in an aqueous Tetra Alkyl Ammonium Hydroxide developer. The procedure takes advantage of the chemical property of the EO/PO surfactant to complex with aqueous cobalt thiocyanate solution to form a blue cobalt containing dye. The coupled dye is soluble in methylene chloride and visible at lambda 620 nm. The amount of dye formation is directly proportional to the amount of EO/PO surfactant present in the sample, over an established range. The analytical method provides precise and accurate quantitation of the EO/PO surfactant in the resist developers. It is relatively easy to perform and enables the user to qualify a resist developer with respect to its surfactant content. Also, the method developed is sufficiently general and can be applied to other types of nonionic surfactants presented in resist developers.

Design and development of high-etch-rate organic bottom antireflective coating for sub-100-nm node and beyond

As the semiconductor industry sails into the 100nm node and beyond, enabled by the integration of ArF lithography, new Bottom Antireflective Coatings (B.A.R.C.s) are required to address challenges associated with this new technology. Of these challenges, higher etch rates and better compatibility with the over coated resist are of central importance. New polymer platforms and additives in B.A.R.C. formulations will be required to overcome these challenges. The intent of this publication is to introduce our newly developed B.A.R.C.s designed to addresses the challenges of ArF lithography. All are currently available for integration into mass production of sub 100nm integrated circuit devices.

Development of 193-nm B.A.R.C.s for dual damascene applications

Full and/or partial filling of 193 nm antireflective materials in contact holes is required for dual damascene applications. One of the major challenges for via filling is to minimize various fill bias associated with via size, via pitches and wafer size to an acceptable level. Toward this aim, various formulations were prepared and tested on different types of wafers using different processing conditions. It has been found that both the properties of the filling materials (e.g., molecular weights, glass transition temperatures, etc.) and processing conditions (e.g., spinning speed, dispense modes, baking temperatures, etc.) affect the filling behaviors. This paper presents our recent progress in the development of 193 nm B.A.R.C. materials designed for the dual damascene process. Through screening of the B.A.R.C. materials and optimization of the processing parameters, we have successfully developed two types of B.A.R.C. materials, namely, AZ EXP ArF-2P1 and AZ EXP ArF-2P5A, both of which show good filling performance.

Performance impact of novel polymeric dyes in photoresist applications

Dye compounds are commonly used in photoresists as a low cost and effective way to control swing and/or standing wave effect caused by thin film interference as well as reflective notching by reflective light from highly reflective substrate and topography. Convention dyes are typically a monomeric compound with high absorptivity at the wavelength of exposure light and compatible with the resist system selected. Because of the monomeric nature, conventional dyes are relatively low in molecular weight hence their thermal stability and sublimination propensity has always been an issue of concern. We recently synthesize several highly thermal stable diazotized polymeric dyes. Their thermal properties as well as compatibility with resist system were investigated. The impact of polymeric dyes on the resists lithographic performance, swing reduction and reflective notching control are discussed.

Process and performance optimization of bottom antireflective coatings: II

The newly developed AZ BARLi II coating material is a photoresist solvent-based bottom antireflective coating (BARC) for i-line lithographic application. The coating material has good compatibility with common edge bead removal solvents such as ethyl lactate, PGME, or PGMEA mixed with ethyl lactate or PGME. To evaluate the BARC material, its chemical compatibility with common EBR solvents has been tested by several analytical techniques including liquid particle counts and surface defect studies. Both top and bottom EBR dispense processes have been investigated and optimized. Improvements on edge roughness, visual cleanliness, and the BARC coating buildup at the edge will be discussed in this paper.

Synthesis of diazonaphthoquinone (DNQ) photoactive compounds (PACs) using ion exchange resins

There is a continuing need to prepare PACs with less ionic impurities. In a typical synthesis, a Diazonaphthoquinone (DNQ) sulfonyl chloride is added to a phenolic compound with an amine catalyst. The photoactive compound (PAC) and an amine salt are formed. After the synthesis, the PAC is washed well with water or mixture of solvents to remove the ionic impurities (the amine salts). However, resist specifications are now at the ppb levels. Residual ionic impurities influence photospeed, particle formation, corrosion, dark film loss, etc. The process to remove the unwanted ionic impurities is costly and time consuming. A new method has been developed in our laboratory to prepare DNQ PACs using ion exchange resins. About a 20 fold decrease in ionic contamination has been observed with this method. The procedure is cost effective and can be applied to PACs with different backbones.