Advanced Alkali Cleaning Solution for Simplification of Semiconductor Cleaning Process

Abstract

NH4OH/H2O2/H2O (called APM or SC–1) cleaning combined with megasonic irradiation is found to feature outstanding removal efficiency for various types of particulate contaminant. The conventional APM cleaning, however, allows metallic impurity in solution to adhere onto substrate surface, and it must be followed by acid cleaning such as HCI/IH2O2/H2O (called HPM or SC–2) cleaning to remove metallic impurity from substrate. The advanced APM cleaning using MC–1 which is alkali cleaning agent containing chelating agent has been developed, and this new cleaning is found capable for preventing various metallic impurities including Al in solution from contaminating substrate surface. Besides, with cleaning conditions optimized, the advanced APM cleaning using MC–1 can also remove metallic impurity from substrate surface. In short, this modified APM cleaning is capable for removing particle and metallic impurity at the same time, which is not possible with the conventional cleaning technology. The cleaning process of semiconductor manufacturing process can be simplified if HPM cleaning is eliminated by introducing the advanced APM cleaning using MC–1. This leads to drastic reduction of cleaning cost and improvement of throughput of the cleaning process.

Synchrotron radiation-induced total reflection X-ray fluorescence analysis

“…In lower pH solutions, it is expected that Cu ions are electrochemically reduced and deposited on the surface as metallic particles [65]. Conversely, in higher pH solutions, Cu ions are precipitated and included in the oxide layer as a metal oxide/hydroxide [66]. Since UPW has a neutral pH, both reaction mechanisms are available for Cu deposition, so it is expected that other factors (e.g., amount of dissolved oxygen) play an important role in the deposition of Cu on silicon surfaces from UPW solutions.…”

Reaction of cyanide ions with copper on Si surfaces and its use for Si cleaning

“…Therefore, the elimination of defect states can improve the solar cell performance which strongly depends on the dark current density. When the conversion efficiency of the pn-junction Si solar cells is relatively low (e.g., 14.5%), it is increased by the cyanide treatment ( Table 2). The relatively low efficiency is likely to be caused by defect states.…”

“…These cleaning methods require high temperatures at 50-80°C, and moreover the cleaning accompanies etching of Si in nm order, which makes LSI fabrication processes very complicated. Recently, inclusion of chelating agents such as ethylene-diamine-tetraacetic acid (EDTA) in the cleaning solutions is found to decrease the metal concentration adsorbed on the surfaces [13,14].…”

X-ray Absorption Spectroscopy on Copper Trace Impurities on Silicon Wafers

“…For metal contamination during the wet cleaning process, there are two alternative reaction pathways in accordance with pH value of the solution. In lower pH solutions, it is expected that metal ions are electrochemically reduced and deposited on the surface as metallic particles [2] Conversely, in higher pH solutions, metal ions are precipitated and included into the oxide layer as a metal oxide/hydroxide [3].…”