Cleanroom
(Room 1.06 - First Floor)
Overview:
The Cleanroom is a specialist environment for the engineers of tomorrow. It has its own air conditioning plant, which allows temperature, humidity and air cleanliness to be tightly controlled. Users must wear special protective clothing and observe stringent operating protocols. The facility is over one hundred times cleaner than a normal laboratory, allowing the definition of features as small as one micron (0.001mm).
The Cleanroom allows students to get real experience of the micron-scale devices that underpin much of modern life, including:
- Microelectronics (resistors; capacitors; diodes; transistors)
- Optoelectronics: Light emitting diodes (LEDs); solar cells; waveguides
- Radio frequency (surface acoustic wave filters; antennae)
- Microsensors (chemical; biochemical; microfluidic)
- Micromechanics (cantilevers; oscillators)
Prior to entry to the cleanroom, the physical layout of micro-devices are designed using industry-standard software tools (ECAD). These tools can also be used to simulate the performance of the device, thus maximising the chance of success.
Device manufacture falls into three main process areas: wet chemistry; photolithography and vacuum processing. The wet chemical processes take place in seven laminar flow cabinets, which enable noxious fumes to be removed. The photochemical processes are conducted in the Yellow Room, where the air is even cleaner (one thousand times cleaner than outside) and the lights are filtered to remove the blue end of the visible spectrum. The vacuum processes take place in chambers that can be evacuated to a pressure of 10-9 atmospheres. By carefully following a predefined sequence of wet chemistry; photolithography and vacuum processing, it is possible to manufacture a near-infinite range of devices.
The starting materials are small pieces of semiconductor, ceramic or glass that have been cleaved from a wafer. These pieces must be carefully cleaned before any fabrication is attempted.
The layouts for the required structure are defined on the surface of the substrate by using a printing technique called photolithography. In this technique a thin layer of photosensitive polymer is spin-coated onto the substrate; the polymer is then exposed to UV light through a laser-written shadow mask; finally, the exposed areas of the polymer are removed. This process results in a substrate that is coated with a polymer copy of the design on the shadow mask.
The patterned substrate can be selectively modified: Either in a vacuum chamber, by the selective deposition or removal of metals, insulators and semiconductors; or by further wet chemical processing, such as acid etching and electroplating. It is also possible to perform heat treatments of the substrates.
Following device fabrication, performance can be assessed using a range of electrical and optical test equipment. The results can be compared with the theoretical insights gained in lectures.
- Students will learn:
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- How to work safely and efficiently in the specialist environment of the cleanroom.
- How to design micron-scale devices using industry-standard software.
- How to manufacture micron-scale devices using standard fabrication tools.
- How to perform electrical and optical tests on micron-scale devices.
- What equipment is in this lab?
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- Plasma etching (oxygen and argon)
- Thermal evaporators
- Inert atmosphere tube furnace
- Desktop rapid thermal annealer (RTA)
- Optical microscopes with digital cameras
- Probe stations
- Source-measurement units (Keysight B2900)
- LCR meters (Keysight)
- Solar simulator (Newport multi-LED 0-1 sun)
- Spinner
- Mask aligners (LED and mercury arc technology)
- Mask writer (Heidelberg µPG101) Min. feature size = 1µm
- Diamond stylus surface profilometer (Dektak)
- Wire bonder
- Sputter coater (DC and RF)
- Links to other Departments:
- Which staff are in this lab?
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- Dr Gavin Williams, Senior University Teacher
- Dr Sheida Faraji, University Teaching Associate
- Peter Trend, Teaching Technician
- Abigail Eades, Assistant Technician
- Request Use of Equipment:
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Please email mee-cleanroom@sheffield.ac.uk with:
- Your name
- Your degree & year of study
- What equipment you want to use and why
Please allow 3-5 working days for a response.