Lab Layouts
type | ACADEMIC status | COMPLETED year | 2019
Programme & Equipment
IIT Bombay has some of the foremost research facilities in the country, including a state-of-the-art facility for research into nanotechnology. At such a facility, the fabrication, testing and study of silicon wafers would be undertaken. However, research into such fields demands a very particular kind of building to be designed. The equipment is extremely sensitive to movement and light, wherein the readings or processes can be affection by the vibrations of passing vehicle. Certain processes (such as lithography), which rely on photochemical reduction processes would be ineffective with the slight variations in natural light - which has a colour temperature of around 5000K.
In designing the labs, there is a slight variation: there are Class 100 or Class 1000 labs, rated at 1000 suspended particles per cubic meter, and Class 10000 labs, rated at 10000 suspended particles per cubic meter. By contrast, a regular room at sea level has about 1000000-10000000 particles per cubic meter. The labs thus rely on multiple seals, an air-shower and a vestibule area to ensure that no stray particles are accidentally allowed into the clean rooms. This, along with the fact that all labs have between 20 to 50 HEPA and ULPA filters, concentrated around the equipment and work areas, ensure that dust particles do not come in contact with the equipment.
Furthermore, the equipment needs to function at a temperature of about 22-24 degrees Celsius, and the equipment cannot be turned off - this means that mechanical ventilation and air-conditioning will have to be kept running at all times - even a slight rise in temperature could destroy some extremely expensive machinery. All incoming water must be purified and deionised (i.e., all charged particles must be removed) before it is used in any of the machines - and waste water from these processes cannot be re-used for any other function.
Each piece of equipment requires a certain amount of space around it for peak functionality, as well as a certain "back end" area where vacuum pumps or water purifiers that feed into the equipment will be located. Below, I've created a method of arranging the equipment in correlation to other equipment used in the same process, and looked at the area requirements for each as a part of the entire process.
There are broadly 4 types of processes that are conducted in a nanotechnology lab: characterisation, lithography, and etching and deposition. Of these, characterisation is usually the least demanding process in terms of areas and specialised equipment of built conditions required. Lithography, on the other hand, requires vast arrays of back-end services, yellow rooms and ultra-clean environments - and is required to be on the ground floor (or underground). Etching and deposition (done in a Fabrication Lab) are relatively straightforward processes that do not require extensively clean areas; however, they do require more human presence - as do the characterisation labs, where the nanotechnology is studied.
In planning the labs, I created the "blocks" illustrated above to assign an area or dimension to all the devices and set-ups, and placed them in congruence with the equipment they would most likely be used with, so as to streamline fabrication or lithography processes. You can click on the image to zoom in for more details on the equipment used.
Lab Types & Layouts
Once I was able to assign an area value or dimension to each equipment, I started looking at the equipment's primary requirements, i.e., should I be operated from the ground floor, does it need special lighting, etc. In doing this, I have created 4 types of labs and clean rooms (each have varying classes; some may be a Class 100, others may be a Class 10000): the ground floor lab, the yellow room, the fabrication lab, the characterisation lab.
It's important to note that some of the labs may seem almost empty, this is because the equipment required in these labs is upgraded on average every 10 - 15 years, and rather than build a new lab to house the new equipment, enough space is allowed for growth and expansion in the existing labs - ensuring these labs preserve functionality for a far higher time-scale. Moreover, equipment placed in tight clusters increases the chance of contamination; and makes it more difficult to seal off or quarantine contaminated equipment.
The ground floor labs contain highly specialised equipment that has a margin of error of a fraction of a nanometer - slight perturbations from building oscillations due to lateral forces such as wind would throw all readings or processes off. Moreover, the labs would need to be insulted from all electromagnetic interference, which is why they are generally placed underground. Labs are divided into two areas: the equipment bay, and the work area. In this kind of lab, the equipment bay is larger than the work area because of the larger scale of equipment and fewer people who actually work in these labs (about 2 - 4). This is a Class 100 - Class 1000 clean room.
The yellow room also contains specialised equipment (required for lithography) which cannot function in any light with a colour temperature higher than 3000 K. This is because higher spectrums of light will react with the chemicals of the surfaces of the silicon wafers. Along with lithography, associated processes such as spin-coating and etching and deposition would also take place. Like the ground floor labs, these labs have a larger equipment bay as the equipment requires a larger operating area and there are fewer scientists or technicians working in this kind of lab. This is a Class 1000 - 10000 clean room.
The fabrication lab is marginally less specialised as compared to the labs described above. Fabrication labs are ones in which the silicon wafers are created and prepared for lithography or etching, through the process of deposition. A layer of liquid material a few molecules in thickness is deposited on a silicon wafer by evaporation and controlled condensation. This process requires a series of machines, and they have been placed in sequence in the equipment bay, abutting the workspace - allowing the scientists and technicians continuous access to the machines to move the silicon wafers along the "assembly line". Since these labs generally see higher footfall, the workspace has been expanded to accommodate 6-8 scientists and technicians. This is a Class 10000 - 100000 clean room.
The characterisation lab is where the finished silicon wafers are tested and studied. Some characterisation labs are located on the ground floor (such as the Scanning Electron Microscope lab) because the equipment in those labs is extremely sensitive. However, characterisation can also be done with tabletop microscopes and equipment that can function with a simple anti-vibration table. All labs contain a set of anti-vibration tables that are specially designed to actively counteract vibrations from a moving building. These labs contain few equipment and have a higher footfall, so like the fab-lab, the workspace is larger than the equipment bay. Characterisation labs can range from Class 100 - 1000000 clean rooms, depending on their function and the equipment they house.
Lab Technology
To allow the labs to run at peak efficiency while keeping with the canons of sustainability that were looked at in earlier pages requires several different building technologies layered upon each other. This layering achieves 4 major things. Firstly, a complex slab system helps mitigate the vibrations that would otherwise be found at upper levels of a building; secondly, structural frames in the walls isolate the entire lab from a flexible superstructure; thirdly, multi-layered walls prevent heat gain or energy loss from external walls; and lastly, specialised building materials help keep the interior of the lab hermetically sealed and functioning smoothly.
Below, I've described the technologies that make this possible, along with a short technical explanation of how they work.
The slab of each lab consists of various sections operating in tandem to reduce vibration and create two or three seals between labs and contaminants. The sections are as follows.
A 600MM-deep precast hollow core RCC slab is the base of the entire structure, supporting all the flooring and the labs. This heavy slab acts as a ballast, weighing down the superstructure and making sure it does not oscillate too much. This slab is not attached to the external wall structure.
An airtight seal with a refuse air channel pumping "used" air out of the bottom of the lab. The air outflow is based on the location of HEPA and ULPA filters in the ceiling panels that blow filtered air downwards through the flooring system and into the outflow, creating a series of air curtains that prevents contamination by dust or particulate matter.
Perforated floor tiles sitting on a framework attached to the hollow-core RCC slab. The workspace, which is where most human activity will take place has this kind of perforated steel floor (by Puracore) - the HEPA and ULPA filters blow air directly downwards, ensuring that stray particles are blown through the perforated flooring and are removed through the refuse air channel.
An array of anti-vibration pads and mechanical vibration isolators are fixed to the hollow-core RCC slab, at the same level as the perforated flooring's framework. The entire equipment bay is supported on this array, effectively mitigating all of the vibrations from the surrounding structure.
A secondary 250MM-deep pre-tensioned, high grade precast RCC slab with an anti-static coating is what makes up the equipment bay. This is supported by the array of vibration isolators and is completely separate from the rest of the structure save for a rubber gasket that runs along its periphery. This slab is essentially "floating" independent of the rest of the structures, ensuring all vibrations are completely mitigated. An anti-static coating prevents the build-up of dust particles by countering any static charge in the flooring, allowing the airflow to blow out any contaminants.
A flexible coving, completely flush with the wall panels and flooring that ensure that there are no corners where particles can settle, rendering a clean room permanently contaminated and necessitating drastic cleaning measures. For this reason, the wall panelling, flooring tiles, ceiling tiles, light fixtures, flush finish doors and coving strips are all sourced from a singular manufacturer - Puracore. This ensures that all elements fit together seamlessly and there is no chance of accidental contamination or leaks (in case of pressurised labs).
The next part in this system is the walling, a separate structure, described below.
Isolating the equipment bay and operational area of the lab from the external structure, this walling system is propped up by a vierendeel truss braced with Penguin Vibration Dampers (PVD, developed by Penguin Engineering, used to fortify buildings against seismic vibrations) that rests directly on the superstructure - and is isolated from the slab completely.
A 50MM-thick honeycomb wall panel with a flush joint (by Puracore) is the innermost layer of this wall. The importance of having flush finishes on all internal surfaces is so that there is no edge (even a millimeter wide) onto which dust of particulates can settle, and it is much easier to clean and maintain.
A PVD-braced truss supports this walling system independent of the lab slab, and creates an insulating air gap between the internal walls and the external walls. This helps prevent the internal lab from heating up by direct conduction of heat from the exterior walls to the internal walls, making the lab more energy efficient in terms of artificial cooling.
A Rapicon wall panelling system for the lab's external wall, a sustainable and lightweight alternative to regular brick or fibreboard walls, with special joints that create an airtight seal - ensuring that no particulates leak through the external walls. These walls can easily be dismantled and recycled or re-used without generating excess waste.
A terracotta wall cladding system from Terreal is the external cladding on walls that are exposed directly to the elements. These panels act as a barrier against weathering and damage by rain for the external walls. As these are hollow-core panels, they provide an additional layer of insulation against heat gain from external temperatures. Moreover, these panels can easily be replaced if damaged or broken, and waste materials can be recycled, re-used or crushed to create aggregate.
This 4 layer walling system serves two main purposes: it isolates the lab from vibrations and external contaminants, and ensures that there is minimal heat gain, allowing the air conditioning system to function more efficiently.
The false ceiling systems employ 50MM-thick Honeycomb ceiling panels fixed onto a specialised flush framework from Puracore. The sizes of these ceiling panels are identical to the flush panel lighting and HEPA/ULPA filter airflow units that fit into the same standardised framework.
Thus, these lab modules are able to boast thermal efficiency, sustainable material use (where possible), complete vibration mitigation and multi-layer sealing against contaminants by using several layers of walls, slabs, and ceilings to make a fully closed module.
This page is part of the expanded series about my design dissertation completed in April 2019. On the links below, you can continue to "Design Drawings", the next in this series.