Foturan (notation of the manufacturer: FOTURAN) is a

photosensitive glass Photosensitive glass, also called photostructurable glass (PSG) or photomachinable glass, is a glass in the lithium-silicate family of glasses onto which images can be etched using shortwave radiations, such as ultraviolet. Photosensitive glass ...

by SCHOTT Corporation developed in 1984. It is a technical

glass-ceramic Glass-ceramics are polycrystalline materials produced through controlled crystallization of base glass, producing a fine uniform dispersion of crystals throughout the bulk material. Crystallization is accomplished by subjecting suitable glasses t ...

which can be structured without

photoresist A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronics industry. T ...

when it is exposed to

shortwave radiation Shortwave radiation (SW) is thermal radiation in the optical spectrum, including visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) spectra. There is no standard cut-off for the near-infrared range; therefore, the shortwave radiatio ...

such as

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

and subsequently etched. In February 2016, Schott announced the introduction of Foturan II at Photonics West. Foturan II is characterized by higher homogeneity of the photosensitivity which allows finer microstructures.

Composition and Properties

Foturan is a

lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...

aluminosilicate Aluminosilicate refers to materials containing anionic Si-O-Al linkages. Commonly, the associate cations are sodium (Na+), potassium (K+) and protons (H+). Such materials occur as minerals, coal combustion products and as synthetic materials, of ...

glass system doped with small amounts of

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

oxides and

cerium Cerium is a chemical element; it has Chemical symbol, symbol Ce and atomic number 58. It is a hardness, soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it ...

oxides.

Processing

Foturan can be structured via UV-exposure, tempering and

etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other type ...

: Crystal

nucleation In thermodynamics, nucleation is the first step in the formation of either a new Phase (matter), thermodynamic phase or Crystal structure, structure via self-assembly or self-organization within a substance or mixture. Nucleation is typically def ...

grow in Foturan when exposed to UV and heat treated afterwards. The

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

ized areas react much faster to

hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling p ...

than the surrounding vitreous material, resulting in very fine

microstructures Microstructure is the very small scale structure of a material, defined as the structure of a prepared surface of material as revealed by an optical microscope above 25× magnification. The microstructure of a material (such as Metallography, m ...

, tight tolerance and high

aspect ratio The aspect ratio of a geometry, geometric shape is the ratio of its sizes in different dimensions. For example, the aspect ratio of a rectangle is the ratio of its longer side to its shorter side—the ratio of width to height, when the rectangl ...

Exposure

If Foturan is exposed to

in the

ultra-violet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of the ...

-range with a

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

of 320 nm (eventually via

photomask A photomask (also simply called a mask) is an opaque plate with transparent areas that allow light to shine through in a defined pattern. Photomasks are commonly used in photolithography for the production of integrated circuits (ICs or "chips") ...

contact lithography Contact lithography, also known as contact printing, is a form of photolithography whereby the image to be printed is obtained by illumination of a photomask in direct contact with a substrate coated with an imaging photoresist layer. History The ...

or proximity lithography to expose certain patterns), a chemical reaction is started in the exposed areas: The containing Ce³⁺ transforms into Ce⁴⁺ and frees an electron. :

\mathrm

Tempering

During the

tempering (~ 500 °C), the Silver-ion Ag⁺ will be transferred into Ag⁰ by scavenging the electron released from Ce³⁺. :

\mathrm

This activates the agglomeration of atomic silver to form nanometer-scale silver clusters :

\mathrm

During the subsequent crystallization tempering (~560-600 °C), lithium metasilicates (Li₂SiO₃

) forms on the silver cluster nucleation in the exposed areas. The unexposed glass, otherwise

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is a characteristic of a crystal. The terms "glass" and "glassy solid" are sometimes used synonymousl ...

, remains unchanged.

Etching

After tempering, the crystallized areas can be etched with

20 times faster than the unexposed, still

glass. Thus, structures with an

of ca. 10:1 can be created.

Ceramization (Optional)

After

, a

ceramization Polymer derived ceramics (PDCs) are ceramic materials formed by the pyrolysis of preceramic polymers, usually under inert atmosphere. The compositions of PDCs most commonly include silicon carbide (SiC), silicon oxycarbide (SiOxCy), silicon nitrid ...

of the entire substrate after a 2nd UV-exposure and thermal treatment is possible. The crystalline phase in this stage is lithium disilicate Li₂Si₂O₅.

Product characteristics

* Small structure size: Structure sizes of ~ 25 μm are possible * High aspect ratio:

Etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other type ...

ratios of > 20:1 make

of > 10:1 and a wall angle of ~ 1-2° possible * High optical transmission in visible and non-visible spectrum: More than 90%

transmission Transmission or transmit may refer to: Science and technology * Power transmission ** Electric power transmission ** Transmission (mechanical device), technology that allows controlled application of power *** Automatic transmission *** Manual tra ...

(substrate thickness 1 mm) between 350 nm and 2.700 nm * High temperature resistance: Tg > 450°Celsius * Pore-free: Suitable for

biotech Biotechnology is a multidisciplinary field that involves the integration of natural sciences and engineering sciences in order to achieve the application of organisms and parts thereof for products and services. Specialists in the field are kn ...

microfluidics Microfluidics refers to a system that manipulates a small amount of fluids (10−9 to 10−18 liters) using small channels with sizes of ten to hundreds of micrometres. It is a multidisciplinary field that involves molecular analysis, molecular bi ...

application * Low self fluorescence * Hydrolytic resistance (acc. to DIN ISO 719): HGB 4 * Acid resistance (acc. to DIN 12116): S 1 * Alkali resistance (acc. to DIN ISO 695): A 2

Foturan in the scientific community

Foturan is a widely known material in the

material science A material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geol ...

community. As of October 30, 2015,

Google Scholar Google Scholar is a freely accessible web search engine that indexes the full text or metadata of Academic publishing, scholarly literature across an array of publishing formats and disciplines. Released in Beta release, beta in November 2004, th ...

showed more than 1.000 results of Foturan in scholarly literatures across an array of publishing formats and disciplines. Many of those deal with topics such as * Micromachining Foturan * 3D / laser direct writing in Foturan * Using Foturan for

optical waveguides An optical waveguide is a physical structure that guides electromagnetic waves in the optical spectrum. Common types of optical waveguides include optical fiber waveguides, transparent dielectric waveguides made of plastic and glass, liquid ligh ...

* Using Foturan for volume gratings * Processing Foturan via

excimer An excimer (originally short for excited dimer) is a short-lived polyatomic molecule formed from two species that do not form a stable molecule in the ground state. In this case, formation of molecules is possible only if such atom is in an elec ...

femtosecond laser Mode locking is a technique in optics by which a laser can be made to produce pulses of light of extremely short duration, on the order of picoseconds (10−12 s) or femtoseconds (10−15 s). A laser operated in this way is sometimes r ...

Applications

Foturan is mainly used for

microstructure Microstructure is the very small scale structure of a material, defined as the structure of a prepared surface of material as revealed by an optical microscope above 25× magnification. The microstructure of a material (such as metals, polymer ...

applications, where small and complex structures have to be created out of a solid and robust base material. Overall there are five main areas for which Foturan is used: *

Microfluidics Microfluidics refers to a system that manipulates a small amount of fluids (10−9 to 10−18 liters) using small channels with sizes of ten to hundreds of micrometres. It is a multidisciplinary field that involves molecular analysis, molecular bi ...

Biotech Biotechnology is a multidisciplinary field that involves the integration of natural sciences and engineering sciences in order to achieve the application of organisms and parts thereof for products and services. Specialists in the field are kn ...

(such as

lab-on-a-chip A lab-on-a-chip (LOC) is a device that integrates one or several laboratory functions on a single integrated circuit (commonly called a "chip") of only millimeters to a few square centimeters to achieve automation and high-throughput screening. ...

organ-on-a-chip An organ-on-a-chip (OOC) is a multi-channel 3D microfluidic cell culture, integrated circuit (chip) that simulates the activities, mechanics and physiological response of an entire organ or an organ system. It constitutes the subject matter of si ...

components,

micro mixer Micro may refer to: Measurement * micro- (μ), a metric prefix denoting a factor of 10−6 Places * Micro, North Carolina, town in U.S. People * DJ Micro, (born Michael Marsicano) an American trance DJ and producer * Chii Tomiya (都宮ち� ...

, micro reactor, printheads, titer plates, chip electrophoresis) *

Semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

(such FED spacer, packaging elements or interposer for IC components,

CMOS Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss ", , ) is a type of MOSFET, metal–oxide–semiconductor field-effect transistor (MOSFET) semiconductor device fabrication, fabrication process that uses complementary an ...

memory module In computing, a memory module or RAM stick is a printed circuit board on which Computer memory, memory integrated circuits are mounted. Memory modules permit easy installation and replacement in electronic systems, especially computers such as ...

s) *

Sensors A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

(such as

flow Flow may refer to: Science and technology * Fluid flow, the motion of a gas or liquid * Flow (geomorphology), a type of mass wasting or slope movement in geomorphology * Flow (mathematics), a group action of the real numbers on a set * Flow (psyc ...

- or

temperature sensors Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making up a substanc ...

gyroscope A gyroscope (from Ancient Greek γῦρος ''gŷros'', "round" and σκοπέω ''skopéō'', "to look") is a device used for measuring or maintaining Orientation (geometry), orientation and angular velocity. It is a spinning wheel or disc in ...

s or

accelerometer An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change (mathematics), rate of change of velocity) of the object relative to an observer who is in free fall (tha ...

s) * RF /

MEMS MEMS (micro-electromechanical systems) is the technology of microscopic devices incorporating both electronic and moving parts. MEMS are made up of components between 1 and 100 micrometres in size (i.e., 0.001 to 0.1 mm), and MEMS devices ...

(such as substrates or packaging elements for antennas,

capacitor In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term st ...

filter Filtration is a physical process that separates solid matter and fluid from a mixture. Filter, filtering, filters or filtration may also refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Fil ...

duplexer A duplexer is an electronic device that allows bi-directional ( duplex) communication over a single path. In radar and radio communications systems, it isolates the receiver from the transmitter while permitting them to share a common antenna. ...

switches In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type o ...

oscillators Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

) * Telecom (such as optical alignment chips,

or optical interconnects) By thermal

diffusion bonding Diffusion bonding or diffusion welding is a solid-state welding technique used in metalworking, capable of joining similar and dissimilar metals. It operates on the principle of solid-state diffusion, wherein the atoms of two solid, metallic surfa ...

it is possible to bond multiple Foturan layers on top of each other to create complex 3-dimensional

References

External links

{{Glass makers and brands Glass types Glass-ceramics Glass trademarks and brands Transparent materials German brands