Foturan

Foturan is a photosensitive glass material developed by SCHOTT in 1984 for precision micromachining and glass-ceramic fabrication. Unlike ordinary glass, Foturan can be selectively modified by shortwave ultraviolet exposure and then processed through controlled heat treatment and chemical etching. This combination allows manufacturers and researchers to produce very small channels, cavities, walls, pores, waveguides, and other three-dimensional structures directly in a robust glass substrate, generally without applying a separate photoresist layer. The material is based on a lithium aluminosilicate glass system containing small quantities of silver and cerium oxides. When selected areas are exposed to ultraviolet light, typically around the 312–320 nanometre range and often through a photomask, a photochemical reaction changes the oxidation state of the cerium. Subsequent heat treatment enables silver ions to form nanoscale clusters that act as crystallization nuclei. A further thermal step converts the exposed regions into a lithium-silicate glass-ceramic phase, while unexposed areas remain largely amorphous. The crystallized portions etch substantially faster in hydrofluoric acid than the surrounding glass, creating sharply defined structures with fine dimensions, high aspect ratios, and relatively tight tolerances. Foturan's material characteristics support applications in which dimensional stability, optical performance, chemical resistance, and thermal robustness are important. Structures on the order of approximately 25 micrometres can be produced, while etching ratios above 20:1 can support aspect ratios greater than 10:1 and wall angles of roughly 1–2 degrees. The material can transmit more than 90 percent of light through a one-millimetre substrate across a broad spectral range extending from the near ultraviolet into the infrared. It is also described as pore-free, low in autofluorescence, resistant to hydrolytic attack, and suitable for elevated-temperature processing. The product is used mainly as an engineering substrate rather than as a consumer-facing glass. In microfluidics and biotechnology, Foturan can be used for lab-on-a-chip devices, organ-on-a-chip structures, micromixers, microreactors, printheads, titer plates, and chip-electrophoresis components. Semiconductor and electronics applications include spacers, packaging parts, interposers, and other components for integrated circuits, CMOS devices, memory modules, and flat-panel-related structures. Sensor applications include flow and temperature sensors, gyroscopes, and accelerometers. In RF and MEMS systems, the material may serve as a substrate or packaging element for antennas, capacitors, filters, duplexers, switches, and oscillators. Telecommunications uses include optical alignment components, optical waveguides, and optical interconnects. Multiple Foturan layers can also be joined by thermal diffusion bonding, enabling more complex three-dimensional assemblies. Research communities have investigated the material for micromachining, laser direct writing, optical waveguides, volume gratings, and processing with excimer and femtosecond lasers. SCHOTT introduced Foturan II in 2016, presenting it as a revised material with improved homogeneity of photosensitivity and consequently better potential for finer microstructures. Foturan therefore occupies a specialist position in technical glass, bridging photolithographic processing, glass-ceramic technology, microfabrication, and precision instrumentation.

Foturan was developed by SCHOTT in 1984 as a photosensitive glass intended for controlled microfabrication. Its distinguishing concept was to make selected parts of a glass substrate more susceptible to crystallization and chemical removal through a sequence of ultraviolet exposure, thermal treatment, and etching. This approach gave engineers a way to form small, precise structures in glass without relying on the conventional combination of deposited films, photoresist, and repeated lithographic processing used in semiconductor fabrication. The material belongs to the lithium aluminosilicate glass family and contains silver and cerium compounds that make the photochemical process possible. Ultraviolet illumination changes cerium from a lower to a higher oxidation state and releases electrons. During a nucleation heat treatment at approximately 500 °C, those electrons assist the reduction of silver ions to metallic silver. The silver atoms aggregate into nanoscale clusters, which act as nuclei for subsequent crystallization. During a higher-temperature crystallization treatment, generally in the range of about 560–600 °C, lithium metasilicate forms in the exposed regions. The non-exposed glass remains predominantly amorphous. This difference in structure provides the basis for selective etching. Hydrofluoric acid attacks the crystallized areas much more rapidly than the unexposed glass, allowing channels, cavities, walls, and other patterned geometries to be produced with small feature sizes and high aspect ratios. A later whole-substrate ceramization step can also be performed after a second exposure and thermal cycle. In that stage, a lithium disilicate phase can be formed, changing the final glass-ceramic structure and potentially improving its mechanical or thermal characteristics for a given design. Over time, Foturan became established as a specialist material in microtechnology and materials research. Academic and industrial work has examined conventional micromachining as well as direct laser writing, excimer-laser processing, femtosecond-laser processing, optical waveguides, and volume gratings. Its combination of visible and non-visible optical transmission, low autofluorescence, chemical durability, thermal resistance, and pore-free structure has made it relevant to biotechnology and photonics as well as electronics. Applications developed around five broad areas. In microfluidics and biotechnology, Foturan can provide solid glass bodies containing microscale fluidic networks and analytical features. In semiconductor and electronic packaging, it can be used for spacers, interposers, and packaging structures. In sensing, it supports components for flow, temperature, inertial, and related measurements. In RF and MEMS, it can function as a substrate or package for miniature electrical and electromechanical devices. In telecommunications and photonics, it can be structured into alignment components, optical waveguides, and interconnect-related parts. Thermal diffusion bonding makes it possible to stack several patterned layers and create more elaborate three-dimensional devices. A significant product-development step occurred in February 2016, when SCHOTT announced Foturan II at Photonics West. The newer formulation was presented as having greater homogeneity in its photosensitivity. More uniform response across a substrate is important for maintaining feature quality and dimensional consistency, particularly as microstructures become smaller. Foturan and Foturan II remain niche industrial materials whose importance is primarily measured by their role in specialized fabrication processes, research instruments, microfluidic systems, MEMS, sensors, and photonics rather than by consumer recognition.

• 2016

  Foturan II announced

  [1]Foturanen.wikipedia.org

  SCHOTT announced Foturan II at Photonics West, highlighting improved homogeneity of photosensitivity for finer microstructure production.

• 1984

  Foturan developed by SCHOTT

  [1]Foturanen.wikipedia.org

  SCHOTT developed Foturan as a photosensitive lithium aluminosilicate glass for selective crystallization and precision chemical micromachining.

A specialist technical-glass platform for resist-free or reduced-process-complexity micromachining, emphasizing fine structures, high aspect ratios, optical transmission, chemical resistance, and three-dimensional glass fabrication.

• Photosensitive technical glass · 1984

  Foturan

  The original Foturan material is a lithium aluminosilicate glass doped with silver and cerium oxides. Ultraviolet exposure, nucleation and crystallization heat treatments, and selective hydrofluoric-acid etching allow manufacturers to create fine, high-aspect-ratio structures in a glass substrate. It is used for microfluidic devices, MEMS, sensors, semiconductor packaging, RF components, and optical structures.

• Photosensitive technical glass · 2016

  Foturan II

  Foturan II is a later SCHOTT photosensitive-glass generation announced in 2016. Its stated distinguishing feature is more homogeneous photosensitivity, which can improve process consistency and support the production of finer microstructures than earlier material configurations.

• 2016

  Introduction of Foturan IIProduct launch

  Background

  Demand for smaller and more uniform microstructures increases the importance of consistent photosensitivity across a technical-glass substrate.

  Action taken

  SCHOTT announced Foturan II at Photonics West, presenting improved photosensitivity homogeneity as the main product-generation change.

  Aftermath

  The revised material was positioned for applications requiring finer and more consistent microstructures. The available reference material does not provide sales, adoption, or financial results.

  Source

1. 1Foturanen.wikipedia.org