InGaAs 표면상의 미세오염입자 제거 기구에 대한 연구

Abstract

An alternative way to increase the performance of complementary metal-oxide semiconductor (CMOS) devices is the introduction of high electron mobility channel materials, which is targeted to the implementation of 10 nm technology device. For n-MOS devices, the most promising candidates are III-V semiconductor materials (e.g. InGaAs, InAs, InSb), which has higher bulk electron mobility than silicon. In order to implement these III-V materials into logic devices, one or more chemical mechanical polishing (CMP) steps may be needed. After III-V CMP process, heavy slurry particle contamination was usually observed. To solve the particle issue, new cleaning chemistry should be developed because conventional NH4OH and DHF based post CMP cleaning chemistry did not work for these particles on III-V surfaces. So far, the study of cleaning mechanism for particle removal from III-V compound semiconductor is very limited. Generally, the cleaning mechanism basically involves a slight surface etching and lift off the particles from the surface via electrostatic repulsive force between particles and surface. Especially a research on an etching process of III-V semiconductor using SC2 solution (HCl/H2O2) is actively being carried out. In this study, we have optimized the chemistry of the post-CMP cleaning solution that should be able to clean In0.53Ga0.47As substrate with low defectivity and minimal material loss. First the InGaAs etch rate, zeta potential and component changes on the surface were measured after etching using atomic force microscope (AFM), zeta potential analyzer and x-ray photoelectron spectroscopy (XPS). Based on the results, cleaning test was performed. The silica particles (130, 289 nm) were intentionally deposited on the substrate surface. The specific concentration ratio of SC2 solution was used to clean the contaminated InGaAs surface. The effect of ammonium dodecyl sulfate (ADS) with SC2 solution was also evaluated. Additionally, combination of SC2 and ADS with megasonic process was performed to effectively remove the 130 nm silica particles. Particle removal efficiency (PRE) was measured by counting the number of particles on the surface, before and after the cleaning test, using an optical microscope and field emission scanning electron microscope (FE-SEM). The surface roughness was also measured after the cleaning by AFM. PRE above 96 % was achieved on the InGaAs substrate at optimized cleaning chemistry. Combination of SC2 and ADS with megasonic process is proposed as a cleaning solution for InGaAs surface with minimum material loss.