The Effect of Polymer Molecular Weight and Solvent Type on the Planarization of Spin‐Coated Films

Abstract

Experiments were performed to determine how the physical properties of coating solutions affect the planarization of spin‐coated films. The planarization of lines 25 μm wide and 0.67 μm high by 1 μm thick spin‐coated films were measured for solutions composed of different solvent‐polymer molecular weight pairs. Three solvents (toluene, methyl ethyl ketone, and chloroform), which have different evaporation rates, were selected as a means of controlling the solvent concentration in the film. Four polystyrenes ranging from 3.10 × 10 5 to 8.30 × 10 3 weight average molecular weights ( M w ) were used. Because the film thickness in these experiments was kept constant, the differences in planarization were due solely to the differences in coating materials. For a given solvent, step heights were significantly reduced by lowering M w from 310,000 to 44,100 but remained unchanged for reduction below the critical molecular weight M c . The step heights were essentially equal (0.40 μm) for all three solvents for M w < M c . Estimates of the solvent concentration in the film indicated that the solvent probably evaporated within the first few seconds of spin. As a result, the film viscosity increased rapidly so there was insufficient time for leveling before the film became glassy.

Spin coating of conjugated polymers for electronic and optoelectronic applications

“…It has been well documented that the film thickness plays a critical role in the morphology and properties of conjugated polymers and the performance of devices based on polymer semiconductors [1][2][3][4][5][6][7][8][9][10]. Although there have been many studies of the spin coating process for many other materials , including photoresists [12,16,22,23], polyimides [13,24,30], sol-gel materials [25] and polyimide-silica hybrid materials [31], neither experimental nor theoretical analysis of the spin coating of conjugated polymer solutions has been reported.…”

Modulable Nanometer-Scale Surface Architecture Using Spin-Coating on an Adsorbed Collagen Layer

“…The geometry and the location of the surface asperities to be planarized are determinant as well. [26][27][28][29][30][31][32] In this paper, we present an original strategy to create a modulable polymer surface architecture at the nanometer scale. The method involves adsorption of macromolecules on a polymer surface followed by spin-coating of an appropriate solution.…”

A Parametric Study of Spin Coating over Topography

“…1998, 37, 2223-2227 purposes of comparison, some flat substrates were also used. Bullwinkel et al (1995) have also conducted a similar study, but they held the film thickness constant at 1 µm. Consequently, our results cannot be compared directly with theirs.…”