Development of InSb dry etch for mid-IR applications
We present a new chlorine-free dry etching process which was used to successfully etch indium antimonide grown on gallium arsenide substrates while keeping the substrate temperature below 150°C. By use of a reflowed photoresist mask a sidewall with 60degree positive slope was achieved, whereas a nearly vertical one was obtained when hard masks were used. Long etch tests demonstrated the non-selectivity of the process by etching through the entire multi-layer epitaxial structure. Electrical and optical measurements on devices fabricated both by wet and dry etch techniques provided similar results, proving that the dry etch process does not cause damage to the material. This technique has a great potential to replace the standard wet etching techniques used for fabrication of indium antimonide devices with a non-damaging low temperature plasma process. Display Omitted Chlorine-free low-temperature dry etch of MBE grown InSb on GaAs60° positive sloped or nearly vertical etch depending on maskNon-selective process etching through Insb, GaSb and GaAsLow damage process with potential to replace standard InSb wet etch
Chlorine reactive ion beam etching of InSb and InAs0.15Sb0.85/InSb strained‐layer superlattices
We report the first successful application of Cl2 reactive ion beam etching (RIBE) to the dry etching of bulk InSb and InAs0.15Sb0.85/InSb strained‐layer superlattices (SLSs). Etching was performed in a load‐locked ultrahigh vacuum chamber using an electron cyclotron resonance ion source. Etching rates for InSb and InAs0.15Sb0.85/InSb SLS with a 500 eV Cl2 beam at 0.6 mA/cm2 are 280 and 240 nm/min, respectively, compared to 310 nm/min for GaAs. The sputter yield for Cl2 RIBE in this antimonide system is double that obtained by Ar ion milling under identical conditions.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.