不同沉积介质对颗粒粘附和去除的影响

The purpose of this study is to investigate the effect of the different deposition mediums on the adhesion and removal of particles. Polystyrene latex  PSL particles  50  m are deposited on thermal oxide and silicon nitride coated silicon wafers using different suspension mediums: air, isopropyl alcohol  IPA , and deionized water and then removed in a dry environment. The results show that PSL particles deposited on oxide are easier to remove than those on nitride due to a higher van der Waals force in all deposition mediums. In addition, dry particles deposited in air are much easier to remove than those desposited in a liquid medium. When particles are deposited from a liquid suspension, a liquid meniscus is formed between the particle and the substrate, resulting in a capillary force. The capillary force induces a plastic deformation for soft particles such as PSL, which increases the contact area between the particle and the substrate, making them more diffificult to remove. The liquid meniscus evaporates shortly after it is exposed to either a dry air environment or vacuum; however, the plastic deformation of particles would take place mainly due to the initial adhesion force in addition to the short time exposure of the capillary force.

Particle adhesion is one of the main causes of yield loss in the semiconductor industry1 because particles can cause short-circuit or open circuit;2 however, particle adhesion has other useful applications. For example, the adhesion of drug particles to specifific sites is important to the pharmaceutical industry.3 In xerography, the ability to transfer toner particles successfully from the photoconductor to the receiver requires an understanding of the mechanisms of particle adhesion.4,5 In nanomanufacturing,6 researchers have made nanowires out of nanoparticles using directed assembly.

Although there are many published studies on the adhesion and removal of particles, there has been a dearth of studies addressing the effect of the different deposition mediums on particle adhesion and removal. In this paper, three different deposition mediums, air, isopropyl alcohol IPA , and deionized DI  water, were used to deposit polystyrene latex  PSL particles on thermal oxide and silicon nitride wafers. These particles were removed using a spinner in air to observe the effect of deposition mediums on particle removal effificiency  PRE .

Theoretical Background 

Adhesion force and adhesion moment.— The fifirst major adhesion force is the omnipresent van der Waals force. Without any external load applied on the particle, the attractive van der Waals force brings the particle into contact with the surface when a particle is within the force’s range. A liquid meniscus can form between the particle and the substrate when either a liquid fifilm or a high humidity is present. The resulting capillary force makes a large contribution to the total adhesion force. In this paper, we focus on these van der Waals and capillary adhesion forces.