Pit Formation Induced by Copper Contamination on Silicon Surface Immersed in Dilute Hydrofluoric Acid Solution

Abstract

Formation of pitting at copper-contaminated sites on the silicon wafer surface during immersion in dilute hydrofluoric acid solution is elucidated by atomic force microscopy observations and electrochemical methods. It was discovered that the pit formation was promoted by the absence of light and hindered under illumination, irrespective of the conductivity type of silicon. From electrochemical measurement of voltammetry, the system was found to form a corrosion-type redox couple, composed of the anodic dissolution of silicon and the cathodic reduction of hydrogen ions, where the later reaction is enhanced by the presence of copper on the silicon surface. In addition, under illumination, either the cathodic or anodic reaction is enhanced, depending on the conductivity type of silicon due to a large increase in minority carrier concentration due to illumination. For creation of a localized pit, formation of the localized redox couple between copper and the nearby silicon surface is essential. This reaction is allowed under the darkened condition, but is obscured by the overwhelming amount of carriers generated under illumination.

Uniform, Axial‐Orientation Alignment of One‐Dimensional Single‐Crystal Silicon Nanostructure Arrays

“…Therefore, we propose a mechanism that accounts for the formation of 1D silicon nanostructures based on silicon etching and metal deposition electrochemistry in HF-based solution. [20][21][22][23][24][25][26][27][28] The mechanism of electroless silver deposition on silicon and silver-nanoparticle-catalyzed chemical etching process of silicon in HF/Fe(NO 3 ) 3 solution is shown in Figure 4.…”

Fabrication of Single‐Crystalline Silicon Nanowires by Scratching a Silicon Surface with Catalytic Metal Particles

“…Recently, Mitsugi and Nagai reported pit formation induced by Cu contamination in dilute HF solution. [20] They proposed that the local redox couple between Cu and the nearby Si surface is essential to the formation of localized pits, which were formed at the same position as the Cu islands. According to these reports and our experimental results, we believe that the Si/AgNO 3 /HF system is composed of a corrosion-type redox couple: the cathodic reduction of Ag + ions and its counterpart, the anodic oxidation and dissolution of silicon, which occurs locally beneath the Ag deposits.…”

“…The injection of holes from the Fe 3+ /Fe 2+ system into the silicon corresponds to the negative current (cathode process). The cathodic current density on p-type silicon immersed in HF/Fe(NO 3 ) 3 solution can be described by Equation 4 [20] j c = -zek c n S c ox exp(-E a /k B T) (4) where j c is the cathodic current density, z is the number of electrons transferred during the reaction, e is the charge of an …”

Motility of Metal Nanoparticles in Silicon and Induced Anisotropic Silicon Etching

“…[16][17][18] Metallic impurities in silicon (Si) are a major cause of low yields and poor performance of semiconductor devices since metallic impurities in Si have serious detrimental effects on device characteristics. [19][20][21][22] Noble metallic impurities often form mid-gap states, which act as efficient generationrecombination centers, and increase the leakage current of junctions. Fast diffusers such as copper and nickel have a strong tendency to segregate to the interface, which leads to junction shorts and degradation of gate oxide performance.…”