Novel postetch process to realize high quality photonic crystals in InP (original) (raw)
Related papers
Very high aspect ratio of photonic crystals holes in InP
2007
We have used a three-level masking technique to achieve high aspect ratio photonic crystal holes in InP-based materials. The masking consists of a ZEP/Cr/SiO x stack where the ZEP layer is used to open the Cr which on its turn is a good mask for opening the 500nm thick SiO x layer. Subsequently InP is etched in an ICP process using Cl 2 :O 2 at a pressure of 1.4 mTorr. High aspect ratio could be achieved in holes ranging from 160 up to 330 nm in diameter with a maximum of 18 obtained with the narrowest holes having a diameter of 210 and 160 nm.
Photonic band gap material for integrated photonic application: technological challenges
Microelectronic Engineering, 2002
We report on the fabrication of two-dimensional photonic crystals (PCs), aimed at operating in compact photonic systems, for optical communications. The targeted device is an optical add drop multiplexer (OADM) whose operation relies on the wavelength-selective and directional coupling of two optical waveguides. The microstructures are fabricated in an InP-based technology by means of a high resolution electron beam patterning generator (HR-EPBG), silicon nitride mask transfer and deep reactive ion etching (DRIE). Successful fabrication of arrays of holes with nano-scale dimensions is demonstrated with aspect ratios of the order of seven for devices operating in the long wavelength windows.
SPIE Proceedings, 2009
Photonic crystal (PC) devices in the InP/InGaAsP/InP planar waveguide system exhibiting narrow bandwidth features were investigated for use as ultrasmall and tunable building blocks for photonic integrated circuits at the telecom wavelength of 1.55 μm. The H1 cavity, consisting of a single PC-hole left unetched, represents the smallest possible cavity in a dielectric material. The tuning of this cavity by temperature was investigated under the conditions as etched and after the holes were infiltrated with liquid crystal (LC), thus separating the contributions of host semiconductor and LC-infill. The shift and tuning by temperature of the MiniStopBand (MSB) in a W3 waveguide, consisting of three rows of holes left unetched, was observed after infiltrating the PC with LC. The samples finally underwent a third processing step of local wet underetching the PC to leave an InGaAsP membrane structure, which was optically assessed through the ridge waveguides that remained after the under etch and by SNOM-probing.
Wavelength-sized, tunable nanocavity in deeply etched InP/InGaAsP/InP photonic crystals
Optics Letters, 2009
Wavelength-sized point defect cavities coupled to access waveguides are reported for deeply etched InP / InGaAsP / InP two-dimensional photonic crystals. The observed quality factor of 60 is comparable to those found for one-row defect Fabry-Perot cavities and for simple point defect cavities in membranes. The quality factor was changed by varying the number of rows of holes. Upon infiltration of the holes with liquid crystal, frequency tuning was demonstrated.
Deep dry etching process development for photonic crystals in InP-based planar waveguides
Photonic Crystal Materials and Nanostructures, 2004
Chlorine-based inductively coupled plasma etching processes are investigated for the purpose of etching twodimensional photonic crystals in InP-based materials. Etch rates up to 3.7 m/min and selectivity's to the SiN mask up to 19 are reported. For the removal of indiumchloride etch products both the application of elevated temperatures and high ion energy's are investigated. The reactor pressure is an important parameter, as it determines the supply of reactive chlorine. It is shown, that N 2 passivates feature sidewalls during etching, improving the anisotropy. Ions that impact onto the sidewalls, either directly or after scattering with the SiN-mask or hole interior, cause sidewall etching. Highly directional ion bombardment and vertical sidewalls in the SiN-mask are therefore crucial for successful etching of fine high aspect ratio structures.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005
We introduce cyclic reactive ion etching processes for SiO 2 and SiN x hard masks where the fluorine-based etch steps are interleaved with N 2 flushing steps in order to improve the selectivity to electron-beam resists. For SiO 2 etching an etch-step duration of 30 s resulted in a doubled selectivity of almost 4:1 between SiO 2 and poly͑methyl methacrylate͒ ͑PMMA͒ due to a reduced thermal load. We established the pattern transfer from a 200 nm thick PMMA resist into a 600 nm thick SiO 2 layer for 200 nm diameter holes. For SiN x etching we demonstrate improved sidewall verticality, an enhanced etch rate, and suppressed redeposition of etch byproducts for a cyclic process. With the use of an additional 30 nm titanium intermediate layer we show an excellent overall selectivity between SiN x and PMMA of almost 5:1. This process is applied to the fabrication of planar photonic-crystal devices with 3.5 m deep holes in an InP based slab waveguide with an initial PMMA layer thickness of 220 nm.
Cl[sub 2]∕O[sub 2]-inductively coupled plasma etching of deep hole-type photonic crystals in InP
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2006
We have developed an inductively coupled plasma etching process for fabrication of high-aspect-ratio hole-type photonic crystals in InP, which are of interest for optical devices involving the telecommunication wavelength of 1550 nm. The etching was performed at 250°C using Cl 2 /O 2 chemistry for sidewall passivation. The process yields nearly cylindrical features with an aspect ratio larger than 10 for hole diameters near 0.25 m. This makes them very suitable for high-quality photonic crystal patterns.
Optical study of two-dimensional InP-based photonic crystals by internal light source technique
IEEE Journal of Quantum Electronics, 2002
We present the first optical study of 2-D photonic crystals (PCs) deeply etched in an InP/GaInAsP step-index waveguide. Following the same internal light source approach proposed by Labilloy and coworkers for the investigation of GaAs-based 2-D PCs, transmission measurements through simple PC slabs and 1-D Fabry-Pérot (FP) cavities between PC mirrors were performed. Details are given on the experimental setup which has been implemented with respect to the original scheme and adapted to InPbased systems working at 1.5-m. 2-D plane-wave expansion and finite difference time-domain (FDTD) methods are used to fit the experimental data. Out-of-plane losses were evaluated according to a recently introduced phenomenological model. In spite of the complex hole morphology in the measured samples, preliminary results are presented which indicate the possibility of separating different loss contributions from finite etch depth and hole shape. As for 1-D cavities, both FDTD and classical theory for planar resonators are applied in order to deduce the optical properties of the PC mirrors. The origin of an anomalously high transmission observed inside the stopgap is discussed and arguments are given to demonstrate the need for further modeling efforts when working in the bandgap regime.