Design of line seeds for glancing angle deposition

Abstract

This paper presents an enhanced seeding rule for the design and fabrication of line seeds for glancing angle deposition (GLAD). GLAD is capable of creating nanometer-level three-dimensional (3D) features by ballistic shadowing from natural/artificial nuclei at oblique incident angles in physical vapor deposition processes. The GLAD features, including columns, springs, zigzags, and ribbons, are building blocks of a wide range of optical, mechanical, and sensing applications. Nanoribbons can be obtained from sub-100 nm-wide line seeds from GLAD; however, volume production of the ultralong fine lines is difficult by conventional fabrication techniques. Additionally, a general process for designing line seeds for creating nanoribbons, especially line seeds with two-dimensional cross sections, is lacking. This paper fills the gaps by integrating the design, fabrication, and optimization of line seeds for obtaining nanoribbons by GLAD. In this paper, a new seeding theory for line seeds for GLAD is proposed by first introducing an empirical model for accurately determining the percent coverage of the deposition for an incident angle over 70°. We discuss the optimum shape and size of the lines for obtaining continuous solid ribbons by matching the percent coverage under predetermined incident angles in a GLAD process. The thickness of the GLAD ribbons is controllable by the geometric parameters of the seeds; ∼100 nm-thick ribbons are obtained from micrometer-width lines created using conventional photolithography. The design process of parabolic cross-sectional line seeds is demonstrated as an example of applying the upgraded seeding rule. Finally, the fabrication of centimeter-long nanoribbons and the use of the ribbons as templates for nanochannels are demonstrated.