Middleman Model Spin Coating Laboratory for Chemical Engineering Undergraduates

Technological advancement has generated vast growth within microelectronics, and as a result, offers an increasing market of industry positions for new engineering graduates. To best equip the next generation of engineers, it is integral to offer students relevant learning material pertaining to this expanding field. Spin coating stands out as a promising addition to the engineering curriculum due to its widespread application in industry, particularly microelectronics, and reproducibility in college laboratories. As proof of concept, the College of Engineering at Oregon State University developed a spin coating experiment and embedded it into the existing transport phenomena curriculum. The purpose of the experiment is to evaluate the validity of the Middleman spin coating model by comparing experimental film thicknesses to theoretical film thicknesses. Thin films were experimentally achieved by developing a Newtonian mixture from glycerol, deionized water, and dish soap. Spin recipe was varied through spin speed, ramp time, dwell time, and number of individual spin steps. Composition was similarly varied affecting the solutions density, viscosity and contact angle. The wafer’s mass was measured before spinning and then placed onto the chuck of the spin coater. Fluid was then statically applied onto the wafer’s center. The wafer with the puddle of fluid is spun at low RPM to generate a uniform layer. This initial step is followed by a higher RPM step to thin the layer to its final thickness. The final mass of the coated wafer is then measured, and the film thickness is calculated. The students’ experimental number is compared to the theoretical value output by the Middleman model. The dataset generated by the Oregon State is in high agreement with the Middleman model. The scope of this experiment is to expose students to industry relevant problems and encourage free form critical thinking. The experiment has several variables to control, allowing students to venture down numerous solution pathways. The purpose of the experiment is not to arrive at a high agreeance value with the Middleman model; instead, it is to build the intuition of the students by exposing them to industry-relevant problems which often have open solutions.