• Jam, Reza Jafari
• Lasonen, Valtteri
• Ilarionova, Yoana
• Karimi, Mohammad
• Vihervaara, Anton
• Popov, Georgi
• Ritala, Mikko
• Tois, Eva
• Sundqvist, Jonas
• Mester, Lars

Abstract

Area-selective etching(ASE) of polymers is a new, inventive, andsimple self-aligned patterning technique which has the potential tobecome an important method for the fabrication of semiconductor devices.A polymer film is etched by using etchant gases, which diffuse throughthe polymer and are activated by catalytic materials underneath thepolymer. The polymer is decomposed locally on top of catalyticallyactive materials, while on top of catalytically inactive materials,the polymer stays intact. This makes the process area-selective andself-aligned, which avoids edge placement errors and other defects.The patterned polymer can be exploited in subsequent area-selectivedeposition or lift-off processes. In this paper, we study ASE of poly(methylmethacrylate) (PMMA) by using Pt, CeO2, Ti, and Cu as catalyticmaterials in an O-2, H-2, or inert atmosphere.Native SiO2 and Al2O3 were used asnon-catalytic surfaces. The catalytic decomposition of PMMA on Ptand CeO2 in the air was clean; i.e., no intermediates inthe middle of the process or any residue after the process were foundon the surface. It was also demonstrated that very small amounts ofPt or CeO2, even down to a fraction of a monolayer, wereenough to show the catalytic effect. Ti showed a clear catalytic effectin the H-2 and inert atmospheres. Copper oxide, rather thanmetallic copper, was found to promote the decomposition of PMMA inthe H-2 and inert atmospheres. Finally, the feasibilityof the overall patterning process was demonstrated on a 100 nanometerscale by ASE of PMMA followed by atomic layer deposition of Ni usingPt as the catalytic surface and native SiO2 as the non-catalyticsurface.

Topics

• impedance spectroscopy
• surface
• polymer
• semiconductor
• copper
• etching
• defect
• decomposition
• aligned
• atomic layer deposition