by josh perry, editor
researchers at the rochester (n.y.) institute of technology (rit) have created a more efficient fabrication process, called inverse metal-assisted chemical etching (i-macetch), to produce semiconductors that are more reliable and powerful nanotechnologies for numerous applications, such as solar cells, smartphones, telecommunication grids, and developing technologies like quantum computing.
semiconductor devices are created on wafers through a multi-step process to coat, remove or pattern conductive materials. (rochester institute of technology)
according to a report from the institute, the research is also moving beyond silicon to explore the use of indium-gallium-phosphide materials in the process.
“the i-macetch process combines the benefits of two traditional methods—wet etching and reactive ion etching, or rei,” the report explained. “indium-gallium-phosphide is one of several materials being tested to complement silicon as a means to improve current capacity of semiconductor processing.”
as the researchers noted, this is not a brand-new technology but rather “new protocols” for the material with the goal of a more cost-effective and sustainable process.
“semiconductor devices are created on wafers through a multi-step process to coat, remove or pattern conductive materials,” the report continued. “traditional processes are wet etch, where a sample with blocked aspects is immersed in an acid bath to remove substances, and reactive ion etching, where ions bombard exposed surfaces on the wafer to change its chemical properties and remove materials in those exposed regions.
“both have been used to develop the intricate electronic patterns on circuits and use silicon as a foundation for this type of patterning. improving patterning methods by i-macetch could mean reducing fabrication complexity of various photonic and electronic devices.”
the research was recently published in applied materials and interfaces. the abstract read:
“metal-assisted chemical etching (macetch) has been established as a low-cost, benchtop, and versatile method for large-scale fabrication of semiconductor nanostructures and has been heralded as an alternative to conventional top-down approaches such as reactive-ion etching. however, extension of this technique to ternary iii–v compound semiconductor alloys and heteroepitaxial systems has remained relatively unexplored.
“here, au-assisted and inverse-progression macetch (i-macetch) of the heteroepitaxial in0.49ga0.51p/gaas material system is demonstrated, along with a method for fabricating suspended ingap nanofoils of tunable thickness in solutions of hydrofluoric acid (hf) and hydrogen peroxide (h2o2). a comparison between au- and cr-patterned samples is used to demonstrate the catalytic role of au in the observed etching behavior.
“vertical etch rates for nominally undoped, p-type, and n-type ingap are determined to be ∼9.7, ∼8.7, and ∼8.8 nm/min, respectively. the evolution of i-macetch in the ingap/gaas system is tracked, leading to the formation of nanocavities located at the center of off-metal windows. upon nanocavity formation, additional localized mass-transport pathways to the underlying gaas substrate permit its rapid dissolution. differential etch rates between the epilayer and substrate are exploited in the fabrication of ingap nanofoils that are suspended over micro-trenches formed in the gaas substrate.
“a model is provided for the observed i-macetch mechanism, based on an overlap of neighboring injected hole distribution profiles.
“the nanofabrication methodology shown here can be applied to various heteroepitaxial iii–v systems and can directly impact the conventional processing of device applications in photonics, optoelectronics, photovoltaics, and nanoelectronics.”