Anisotropic Etching of Pyramidal Silica Reliefs with Metal Masks and Hydrofluoric Acid

Abstract

This work describes the fabrication of anisotropically etched, faceted pyramidal structures in amorphous layers of silicon dioxide or glass. Anisotropic and crystal‐oriented etching of silicon is well known. Anisotropic etching behavior in completely amorphous layers of silicon dioxide in combination with purely isotropic hydrofluoric acid as etchant is an unexpected phenomenon. The work presents practical exploitations of this new process for self‐perfecting pyramidal structures. It can be used for textured silica or glass surfaces. The reason for the observed anisotropy, leading to enhanced lateral etch rates, is the presence of thin metal layers. The lateral etch rate under the metal significantly exceeds the vertical etch rate of the non‐metallized area by a factor of about 6–43 for liquid and 59 for vapor‐based processes. The ratio between lateral and vertical etch rate, thus the sidewall inclination, can be controlled by etchant concentration and selected metal. The described process allows for direct fabrication of shallow angle pyramids, which for example can enhance the coupling efficiency of light emitting diodes or solar cells, can be exploited for producing dedicated silicon dioxide atomic force microscopy tips with a radius in the 50 nm range, or can potentially be used for surface plasmonics.

Recent advances in techniques for fabrication and characterization of nanogap biosensors: A review

“…The wet etching process is used to strip a blanket film on the wafer surface because of its high selectivity. A schematic illustration of wet etching coupled with the dry etching process is shown in Figure 13 138 …”

“…A schematic illustration of wet etching coupled with the dry etching process is shown in Figure 13. 138…”

Beyond Lambertian light trapping for large-area silicon solar cells: fabrication methods

“…The diameter of the ablated hole is defined by the pulse energy density (fluence), which for the Gaussian beam follows the dependence plotted in Fig. 2(a), here is the radial coordinate of Gaussian fluence (intensity) distribution, is the waist of the beam and is the amplitude of fluence 20 . The linearised equation for the used focusing is plotted by a solid line; see the ∼ 0.1…”

Self‐Replication of Deeply Buried Doped Silicon Structures, which Remotely Control the Etching Process: A New Method for Forming a Silicon Pattern from the Bottom Up

“…However, high doping concentrations cause a transition of silicon from a semiconductor to a conductor, [1,9] which disables its use for complementary-metal-oxidesemiconductor technology. [10] Other attempts use varying mask materials and etchants, [11][12][13][14] electrochemical etching, [15,16] dry etching, and self-assembly of strained substrates [17] or microcontact printing techniques. [18] Methods described in the patent literature use differences in photo-electrochemical properties of silicon doped in different ways.…”