Photoresist and Residue Removal Using Gas-Expanded Liquids

Abstract

Rapid technology development and demands for state-of-the-art generations of integrated circuits bring new challenges to microelectronic device manufacture. Specifically, decreasing dimension sizes may limit the effectiveness of liquid-based removal of photoresist and plasma etch residues. In addition, the hazardous solvents currently in use pose environmental concerns. Gasexpanded liquids ͑GXLs͒ and supercritical fluids may offer cleaning or residue removal approaches that overcome some of the drawbacks of current surface preparation methods. Removal of PHOST ͑polyhydroxystyrene͒ photoresist films has been demonstrated with CO 2 -expanded ethanol ͑up to 75 mol % CO 2 ͒, indicating that the inclusion of CO 2 does not inhibit photoresist removal. In situ interferometry measurements of the PHOST layers allowed insight into the removal mechanism. The GXL mixtures were also invoked to remove post-plasma etch residues using CO 2 -expanded TMAHCO 3 /CH 3 OH. At a temperature of 90°C and pressures above 1000 psig the GXL mixture removed the photoresist and etch residue. Cleaning efficiency depended on CO 2 pressure; at lower pressures the CO 2 reduced the mole fraction of the TMAHCO 3 /CH 3 OH while at higher pressures the CO 2 assisted removal.

Solvation and Solvatochromism in CO2-Expanded Liquids. 1. Simulations of the Solvent Systems CO2 + Cyclohexane, Acetonitrile, and Methanol

“…Pressures in the 0−10 MPa range can be used to tune the properties of GXLs, for example their solvent strength, quickly and easily. For this reason, the use of supercritical gases as “antisolvents” for inducing precipitation in micro- and nanoparticle fabrication has proven to be of considerable practical value. − The enhanced fluidity of GXLs compared to conventional organic solvents also renders them advantageous in separation processes and analytical high-performance liquid chromatography, , in various cleaning applications, and as reaction media. ,− Finally, replacement of pure organic solvents with CO 2 -expanded liquids is envisioned as a means to decrease the environmental impact and economic cost of common industrial processes. , …”

Supercritical CO2–EtOH expanded liquid processing to produce tailored PEEK-WC membranes

“…From a technical point of view, these mixtures are expanded liquids: they maintain part of the characteristics of the original liquid solvent, but are characterized also by a reduced surface tension and higher diffusivity. 25,26 In a previous work, poly(etheretherketone) with cardo group-based (PEEK-WC) membranes were produced by SC-CO 2 assisted phase inversion, 27 but, at all process conditions tested, non-porous surfaces were obtained. This characteristic hinders some applications of these membranes; therefore, in this work we explored an advanced alternative processing of PEEK-WC, using an expanded liquid mixture formed by SC-CO 2 and ethanol to assess the possibility of modulating not only the internal structure of the formed membranes, but also, specically, their surface porosity.…”

Crystalline polymer decoration on multiwalled carbon nanotubes: MWCNT-induced P4VP periodic crystallization in CO2-expanded liquids

“…As such, they reflect a compromise between the use of conventional solvents, which are a major source of industrial pollution, and completely benign solvents like neat CO 2 , whose poor solvent qualities and high pressure requirements have limited its application. In addition to the environmental benefits of GXLs, the ability to readily pressure tune the mole fraction of the gaseous component and thereby alter the solvating power, fluidity, and many other properties of these solvents proves advantageous in a variety of applications, such as materials processing [13,14], analytical separations [15] and cleaning [16], and as media for organic reactions [11,17,18]. CO 2 -expanded liquids (CXLs) are the most commonly used class of GXLs because of the safety and economic advantages of CO 2 .…”