Atomic force microscope based patterning of carbonaceous masks for selective area growth on semiconductor surfaces

Abstract

Carbonaceous masks for selective growth on GaAs substrates were fabricated with high resolution by anodization with an atomic force microscope (AFM). Mask deposition is made by a 15-kV accelerated electron-beam irradiation in a scanning electron microscope. The local anodization of the carbonaceous film under intense electric field is investigated and the main factors for improving resolution and reproducibility are discussed. The “edge effect” of the anodized region, revealed in the electric-field distribution at the tip–water–film interfaces is identified as the main factor responsible for the resolution degradation during patterning. Short forward bias pulse for anodizing the carbonaceous film and the subsequent reverse bias pulse for neutralizing the space charge, locally accumulated during the forward bias, are shown to be effective for the higher pattern resolution and also for deepening the patterning depth. Based on the analysis, a modulated-amplitude pulsed bias mode is proposed and is demonstrated to bring a significant improvement in the resolution and the aspect ratio of patterns made by the anodization. Carbonaceous masks ready for selective area growth of semiconductors alloys were fabricated with the pattern resolution of ∼26 nm, limited by the curvature of AFM cantilever tips.

Nanoscale oxidation of zirconium surfaces: Kinetics and mechanisms

“…[22][23][24] This type of power-law behavior is due in part to the space charge built up in the early period of local oxidation using dc voltages. [25][26][27][28][29][30][31][32][33] Space charge is a consequence of unbalanced ionic reactants and products, mainly O-and H-containing species, generated during oxidation. This in turn leads to oxides with a lower density than expected.…”

“…This behavior is a general characteristic of the AFM-induced anodization process and a similar voltage dependence has been reported for a variety of materials systems. [12][13][14][15][16][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] In our case there is an apparent minimum threshold voltage of 5 V for the growth to initiate which may reflect the resistive or dielectric aspects of the native oxide present on the Zr and ZrN thin films.…”

Size determination of field-induced water menisci in noncontact atomic force microscopy

“…[1][2][3][4][5][6] A key feature of local oxidation lithography is the formation of a liquid meniscus bridging tip and sample surface. [7][8][9][10] Capillary condensation within nanopores is also relevant for other areas such as tribology, 11 wetting at structured surfaces 12 and other scanning probe microscopy applications. 13 Recently several studies have described different aspects of nanometer-size capillaries 14 -17 and electrowetting phenomena.…”

Linewidth determination in local oxidation nanolithography of silicon surfaces

“…Nano-oxidation or local oxidation of semiconductor and metallic surfaces by atomic force microscopy ͑AFM͒ is emerging as a reliable and versatile lithographic method for fabrication of devices and patterning of structures at nanometer scale. [1][2][3][4] A variety of materials have been locally oxidized such as silicon, 5 silicon nitride, 6 GaAs, 7 titanium, 8 niobium, 9 aluminum, 10 carbonaceous films, 11 and organic monolayers. 12 The strong activity devoted to this lithography has allowed us to identify the relevant factors affecting the oxidation process.…”