“…This indicates that a protective copper oxide film forms on the copper surface under an acidic pH because of the local pH increase and the existence of citrate-complex ions when the applied potential is positive. [10][11][12] Thus, the copper-citrate solution used in this study for direct copper ECD on TiN is not appropriate for sample reuse while most noncomplex copper electrolytes work for both deposition and dissolution of copper.…”
Section: Resultsmentioning
confidence: 99%
“…This indicates that a protective copper oxide film forms on the copper surface under an acidic pH because of the local pH increase and the existence of citrate-complex ions when the applied potential is positive. [10][11][12] Thus, the copper-citrate solution used in this study for * Electrochemical Society Fellow.…”
Copper was directly electrodeposited onto TiN diffusion barrier surface without employing a copper seed layer. Depending on the chemical condition of an electrolyte, especially pH, copper deposits on TiN had different nucleation and growth modes. pH of electrolyte was controlled by adding H 2 SO 4 and NH 4 OH to the base solution of pH 3.56, which contained copper-citrate ͑Cu-Cit͒ complexes. Chelating ability of citrate was substantially influenced by pH and it strongly affected the nucleation of copper. Below pH 3.56, progressive nucleation of copper on TiN was mainly found, and irregular growth and low density of 3-5 ϫ 10 7 cm −2 of copper nuclei came out. Above pH 3.56, instantaneous nucleation of copper on TiN, which is desirable for filling of damascene structure, was mainly obtained, and hemispherical copper nuclei were uniformly distributed. Copper nuclei density increased from 5 ϫ 10 8 to 1.5 ϫ 10 10 cm −2 as pH varies from 3.56 to 7.4. It closely approached a value of 2 ϫ 10 10 cm −2 , which is theoretically needed for seedless copper filling in the sub-70 nm damascene structure for ultralarge-scale integration interconnects.
“…This indicates that a protective copper oxide film forms on the copper surface under an acidic pH because of the local pH increase and the existence of citrate-complex ions when the applied potential is positive. [10][11][12] Thus, the copper-citrate solution used in this study for direct copper ECD on TiN is not appropriate for sample reuse while most noncomplex copper electrolytes work for both deposition and dissolution of copper.…”
Section: Resultsmentioning
confidence: 99%
“…This indicates that a protective copper oxide film forms on the copper surface under an acidic pH because of the local pH increase and the existence of citrate-complex ions when the applied potential is positive. [10][11][12] Thus, the copper-citrate solution used in this study for * Electrochemical Society Fellow.…”
Copper was directly electrodeposited onto TiN diffusion barrier surface without employing a copper seed layer. Depending on the chemical condition of an electrolyte, especially pH, copper deposits on TiN had different nucleation and growth modes. pH of electrolyte was controlled by adding H 2 SO 4 and NH 4 OH to the base solution of pH 3.56, which contained copper-citrate ͑Cu-Cit͒ complexes. Chelating ability of citrate was substantially influenced by pH and it strongly affected the nucleation of copper. Below pH 3.56, progressive nucleation of copper on TiN was mainly found, and irregular growth and low density of 3-5 ϫ 10 7 cm −2 of copper nuclei came out. Above pH 3.56, instantaneous nucleation of copper on TiN, which is desirable for filling of damascene structure, was mainly obtained, and hemispherical copper nuclei were uniformly distributed. Copper nuclei density increased from 5 ϫ 10 8 to 1.5 ϫ 10 10 cm −2 as pH varies from 3.56 to 7.4. It closely approached a value of 2 ϫ 10 10 cm −2 , which is theoretically needed for seedless copper filling in the sub-70 nm damascene structure for ultralarge-scale integration interconnects.
“…This effect has been termed cathodic delamination because similar effects can be obtained if the steel is cathodically polarized by means of an external potential [21].…”
The cathodic delamination of a commercial TiO 2 pigmented epoxy coating on abrasive cleaned cold rolled steel has been investigated. The rate of delamination was found to depend on interfacial transport from the artificial defect to the delamination front and thereby the substrate topography, whereas the coating thickness had little influence. The presence of a significant potential gradient between the anode and the cathode and the dependency of the delamination rate on the tortuosity of the steel surface suggests that cathodic delamination is controlled by migration of cations from the defect to the delamination front. This means that abrasive blasting, to some extent, can be applied to control and minimize the observed rate of cathodic delamination. The lifetime of the species causing disbondment suggested that sodium hydroxide or potassium hydroxide and not peroxide species or radicals are the causative agents at free corrosion potential (i.e. without impressed current).
“…The polymer must also adhere well to the surface to prevent undercutting during wet etching [19][20][21] or delamination during metallisation, especially during metal plating where cathodic delamination may occur. 22,23 The reverse coverage is required for the etch-back and lift-off applications depicted in Fig. 2c and d.…”
Section: Overview Of Requirements For Silicon Photovoltaicsmentioning
confidence: 99%
“…The polymer must also adhere well to the surface to prevent undercutting during wet etching 19–21 or delamination during metallisation, especially during metal plating where cathodic delamination may occur. 22,23 Figure 2 Schematics depicting the use of a sacrificial polymer mask for selective: a and c etching; and b and b metallisation. In a and b , the polymer layer covers the majority of the silicon wafer surface, however for the etch-back c and lift-off applications d the polymer is applied (printed) only in localised regions, typically lines, which cover a small fraction of the wafer surface…”
Section: Overview Of Requirements For Silicon Photovoltaicsmentioning
Patterning is fundamental to advancing most technologies. Although the challenge for electronic integrated circuits continues to be reduced feature size other applications have different requirements and challenges. This review contributes insights from silicon photovoltaics where patterning is required for selective doping etching and metallisation. Earlier silicon solar cell devices extensively used optical lithography to fabricate devices in the laboratory with high device efficiencies being achieved. However industrial cell fabrication has largely relied on uniformly doped silicon layers and lower resolution screen-printing for metal electrode formation because optical lithography is considered too expensive and slow. This has resulted in the average energy conversion efficiencies of industrially produced cells remaining on average 5% lower than the value of 25% reported in 1999 for cells patterned with optical lithography. Motivated by the goal of bridging this efficiency gap many new polymer patterning methods which do not require the formation of a qualified mask have been developed for different silicon solar cell designs. These polymer patterning methods fall into two general classes; (i) where the polymer mask is directly printed on the cell surface; and (ii) where a pattern is formed in a polymer layer using printers or lasers to effect the patterning. Many of the methods which are reviewed in this paper although developed with specific photovoltaic requirements in mind may also find applications in other fields of research and technology.
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