2004 Fiscal Year Final Research Report Summary
Electrochemical Maskless Metal Patterning on Silicon Using Photo-excited Carriers
| Project/Area Number |
14350383
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
OGATA Yukio Kyoto University, Inst.Advanced Energy, Professor, エネルギー理工学研究所, 教授 (30152375)
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| Co-Investigator(Kenkyū-buntansha) |
SAKKA Tetsuo Kyoto University, Inst.Advanced Energy, Associate Professor, エネルギー理工学研究所, 助教授 (10196206)
HAMM Didier Kyoto University, Inst.Advanced Energy, Assistant Professor, エネルギー理工学研究所, 助手 (50324702)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Porous silicon / Photo-excitation / Laser / Electrodeposition / Immersion plating / Metal patterning |
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| Research Abstract |
Position-selective metal deposition on p-type silicon was successfully performed by laser illumination in metal-salt solution under cathodic polarization. The scanning of illumination realized metal patterning on silicon without the help of photolithography. The resolution on a porous silicon surface was superior to that on a flat silicon surface. The deposited spot size was 15 μm when using a laser with the beam diameter of 5 μm.
Immersion plating hinders the patterning since the whole surface of silicon receives metal deposition. Less-noble metal systems can prevent this situation, and the metal pattering was demonstrated in nickel, iron, and zinc systems. Copper is a noble metal and unfavorable for the patterning. However, it is possible if the redox potential can be shifted toward the negative direction by complexation. Copper patterning was achieved using a solution consisting of cupric chlorides instead of the use of a copper sulfate solution. In the immersion plating study, we ma
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de two new findings. First, immersion plating of nickel is possible from an alkaline nickel sulfate solution containing ammonium fluorides, and oxidation of the silicon substrate can be prevented in this process. Second, open circuit potential of silicon oscillates spontaneously and persistently during copper immersion plating.
Photo-assisted copper patterning was possible also on n-type silicon by the following method. Porosification of silicon is position-selectively performed by illuminating n-type silicon in a hydrofluoric acid solution under anodic polarization, and then the patterned sample is immersed in a copper sulfate solution. Immersion plating of copper takes place only at the porous surface ; it makes the patterning possible. This patterning utilizes the different reducing abilities between silicon and porous silicon. However, metal deposition on n-type silicon showed some limitations. Only noble metals, which can be immersion-plated, are usable, and careful control of hydrofluoric acid concentration and illumination conditions are crucial. Less
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Research Products
(27 results)
