Among the laboratory premises, three areas can be distinguished: (1) the laboratory's technical support rooms (the so-called machine room) and the changing room, (2) the main part of the laboratory separated from the changing room by an airlock, (3) separate rooms for carrying out the photolithography process (purity class ~100) and performing wet chemical operations (the so-called wet chemistry).
In the main part of the Laboratory (Cleanroom), a constant overpressure is maintained (in relation to the surrounding rooms), which constitutes an effective barrier to all types of dust and contamination, and a constant temperature (approx. 22°C) and air humidity (approx. 40%) are maintained by the air conditioning system. In the main room of the laboratory, a purity class of 1000 is guaranteed. The equipment in the technological laboratory, supported by the skills acquired over many years of research, allows for the implementation of a very wide range of technological processes and research in the field of electronics and photonics (production of semiconductor structures and devices), MEMS/MOEMS microsystems, but also (as has already been proven in practice in recent years) in the field of chemistry (e.g. lab-on-chip, sensors), bio-engineering (e.g. DNA sensors) or materials engineering (research on new materials for use in next-generation integrated circuits, or unusual materials compatible with broadband semiconductors).
3D Tour of the Technology Laboratory:
Technological processes implemented in the Laboratory
- Surface preparation processes of substrates or products
Processes performed in a chemical fume hood under constant negative pressure, which prevents vapors of volatile reagents from escaping into laboratory rooms. The processes implemented are aimed at cleaning, preparing and modifying substrates in liquid solutions before commencing to subsequent technological processes. Substrates used in technological processes are primarily semiconductor wafers (silicon, silicon carbide, gallium nitride, gallium arsenide) and glass wafers (sapphire, quartz). Some research works use metal substrates or finished metal products (steel, titanium), glass optical fibers and ceramic materials (Al2O3, AlN, BN). Various types of chemical reagents and their solutions are used in surface preparation processes.
- Thermal oxidation processes
Processes carried out in a reactor specially prepared for this purpose - a high-temperature furnace. Typical process temperatures range from 700°C to 1200°C. Working gases (oxygen, N2O, NO, nitrogen, argon) are introduced into the quartz tubes of the high-temperature furnace. In the case of wet oxidation process, the steam atmosphere is created using a deionized water saturator, through which nitrogen is fed into the high-temperature furnace tubes. Substrates (tiles) are fed into the furnace on a quartz boat using a quartz manipulator. The most common materials oxidized in this way are silicon and silicon carbide.
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Doping by means of high-temperature diffusion
The doping process by diffusion is carried out in a high-temperature furnace with a quartz tube. The typical process takes place at the temperature of 850°C – 950°C. The carrier gas is nitrogen, the working gas is oxygen and nitrogen. In the case of boron diffusion (B), the source of the dopant are ceramic disks made of boron nitride (BN). In the case of phosphorus diffusion, the source takes a gaseous form. Nitrogen is fed to the saturator filled with POCl3, acting as a carrier gas. The furnace is equipped with an exhaust hood at the pipe outlet, which removes reaction products and unreacted chemical compounds in the gaseous phase during the process, preventing them from entering the laboratory room. A typical material doped under the described conditions are silicon substrates.
- Plasma enhanced chemical vapor deposition (PECVD)
The process of deposition of thin dielectric (oxides and nitrides of silicon) and semiconductor (amorphous silicon) layers in a vacuum reactor equipped with a plasma generator with a frequency of 13.56 MHz and a power of up to 300 W. Typical gases feeding the PECVD reactor are: silane (SiH4 diluted in nitrogen or helium), nitrogen, oxygen and argon. The negative pressure created by vacuum systems prevents gases and chemical products in the volatile phase from escaping from the device into the laboratory room. Additionally, before opening the reactor, it is filled with nitrogen twice and pumped out, which prevents post-reaction gases and reaction products from escaping into the environment after opening the vacuum chamber. Deposition processes are carried out on semiconductor, glass, ceramic and metal substrates described in point 1.
- Reactive ion etching (RIE)
A process used for sputtering and chemical dry plasma etching of dielectric (silicon oxides and nitrides) and semiconductor materials (silicon, silicon carbide, gallium nitride, gallium arsenide) in fluorine and chlorine plasma in a vacuum reactor equipped with a plasma generator with a frequency of 13.56 MHz and power up to 300 W. Argon and nitrogen mixtures are used for ion sputtering. For chemical plasma etching, working gases SF6, CF4, CHF3 are used, often dosed in the form of a mixture with oxygen. The negative pressure created by vacuum systems prevents gases and chemical products in the volatile phase from escaping from the device into the laboratory room. Additionally, before opening the reactor, it is filled with nitrogen twice and pumped out, which prevents post-reaction gases and reaction products from escaping into the environment after opening the chamber.
- Wet chemical etching
Processes performed in a chemical fume hood under constant negative pressure, which prevents vapors of volatile reagents from escaping into laboratory rooms. The processes carried out are aimed at chemical etching of the surface of materials in appropriately prepared chemical solutions. A typical example of such a process is the etching of silicon or silicon carbide in aqueous solutions of potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH). Processes can be modified by adding surfactants to the solution. Isopropyl alcohol is commonly used for this purpose.
- Photolitography
A process used to reproduce shapes in a photosensitive polymer emulsion hardened by ultraviolet radiation. Acetone-based solutions are most often used to process photosensitive emulsions. Photosensitive emulsions are spin-applied onto semiconductor, glass or ceramic substrates.
- Vacuum vapor deposition
A process used for the vapor deposition of thin metallic layers carried out in a vacuum reactor under high or very high vacuum conditions. The basic sources of metals vaporized by heating caused by the flow of electric current are aluminum, chromium and gold. A modified vacuum deposition process using a high-energy electron beam is used to deposit thin layers of refractory metals (titanium, nickel, platinum, tungsten).
- Ion sputtering, reactive magnetron sputtering in RF plasma
A vacuum process used for vapor deposition of thin metallic (titanium, gadolinium, aluminum, hafnium, zinc), dielectric (TiO2, Al2O3, AlN, HfO2) and semiconductor (ZnO) layers. The sputtering process of metallic materials is typically carried out in an argon atmosphere. Reactive magnetron sputtering process, aimed at obtaining materials with dielectric or semiconductor properties, is typically carried out in mixtures of oxygen or nitrogen with argon, sometimes nitrogen with oxygen. The metal sources are high-purity metal targets sputtered ionically or reactively, depending on the working gases used.
Catalog of typical products obtained in the Laboratory:
- ultra-thin (single nm) and ultra-pure dielectric layers with high breakdown resilience,
- thin dielectric layers acting as gate oxides in semiconductor technology, including dielectric layers with high electrical permittivity,
- thin dielectric layers with a modified refractive index for optical applications (anti-reflective layers, protective layers and layers modifying the properties of optical elements),
- thin dielectric and semiconductor layers used as coatings with specific mechanical properties (anti-slip layers, layers with a low coefficient of friction, hydrophilic and hydrophobic layers, etc.),
- thick dielectric layers acting as passivation of high-voltage semiconductor devices,
- structuring of substrates subjected to wet or dry etching processes (anisotropic etching of semiconductor and dielectric materials, anisotropic etching of silicon, production of trench and mesa structures,
- producing mirror-like surfaces for various types of electromagnetic radiation,
- production of periodic structures shaped by photolithography for photonic applications,
- processes of transferring graphene from copper and polymer foils to other types of glass, dielectric and semiconductor substrates,
- semiconductor junctions and diode structures obtained by changing the level of silicon doping as a result of high-temperature diffusion,
- MOSFET/MISFET field effect transistors,
- ion-sensitive ISFET field-effect transistors,
- diodes and power transistors in silicon carbide technology,
- optical radiation detectors, including UV radiation detectors with limited sensitivity to visible radiation,
- X-ray detectors.
