Electrochemical Investigation of Copper Contamination on Silicon Wafers from HF Solutions

Abstract

Copper contamination of silicon wafers from 50:1 HF solutions containing 0 to 100 ppb Cu was studied using dc electrochemical techniques. As the level of copper concentration in HF solutions increased, the corrosion current density and corrosion potential of silicon as well as the amount of copper deposition were increased. Upon addition of a nonionic surfactant, the corrosion potential, corrosion current density, and the extent of copper deposition were decreased. However, the levels of deposited copper and surface roughness were dependent on sufactant concentration. When H202 was added to copper-spiked HF solutions, the open-circuit potential of silicon recovered to a value that is characteristic for silicon immersed in a mixture of H,02 and HF indicating the removal of deposited copper on silicon. InfroductionMetallic contamination of silicon wafer surfaces is an important issue because of its harmful impact on the performance of semiconductor devices. The deleterious effects ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.113.111.210 Downloaded on 2015-06-30 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.113.111.210 Downloaded on 2015-06-30 to IP

Large-radius neutral beam enhanced chemical vapor deposition process for non-porous ultra-low-k SiOCH

“…The PECVD SiOCH film was degraded by etching and increased RI after dipping in HF aq. This is because HF molecules easily attack silicon in Si-O, react to form SiF 6 2-ions, and are dissolved into the solution [24]. We consider that in the NP-SiOCH film methyl guards the Si-O-Si bond against attack from HF aq.…”

Photoinduced electrochemical deposition of Cu onp-type Si substrates

“…Background plating on the entire Si area is possible due to the availability of electrons generated by the anodic half reaction between Si and F Ϫ . 11,12,14 Since anodic electrochemical processes are essential for the occurrence of background plating, and these are partly dependent on the solution composition, we studied in more detail the dependence of both the dot morphology and the extent of background plating on the chemical composition of the plating solution.…”

“…Spontaneous precipitation of copper from electrolytes containing Cu ions and F Ϫ was reported to take place on n-type Si (n-Si͒, p-type Si (p-Si͒, and polycrystalline Si ͑poly-Si͒ substrates with or without laser illumination. [11][12][13][14] In microelectronic circuit microfabrication, this process can lead to unwanted contamination and device failure; consequently, modeling 14 and experimental activities were performed with the objective to avoid it. The addition of suitable surfactants 11 or substrate biasing during HF etching 14 was found to reduce Cu contamination.…”

Selective Deposition of Thin Copper Films onto Silicon with Improved Adhesion

“…In addition, many studies have also been carried out on the galvanic deposition of copper from fluoride containing solutions. [4][5][6][7][8][9][10][11] In contrast to electroless deposition, galvanic displacement deposition requires no prior activation of the surface and is truly selective to silicon surfaces. Thus, it provides an attractive deposition method for copper interconnects or seed layers for subsequent metallization.…”

“…Independent of the substrates (i.e., p-or n-type, single-or polycrystalline silicon), the copper films exhibit a very high adhesion to the substrate and resistance to scratching, particularly compared to films obtained according to the published literature. [4][5][6][7][8][9][10][11] The particular structure of the copper film, likely due to the 3D growth, has a strong influence on the electrical resistivity of the films as deposited. Compared to a sputtered copper film on a titanium nitride seed layer, which exhibits resistivity of about 300 mΩ/ᮀ, the displaced copper as deposited is characterized by resistivity values over ten times higher.…”