MBE
| File:Tool MBE.jpg | |
| Essentials | |
|---|---|
| Full name | Varian GEN II |
| Manufacturer | Custom |
| Description | Molecular beam epitaxy system |
| Location | MBE lab (03.2.213A, 03.2.217, 03.2.217A) |
| Responsibility | |
| Primary | Claus |
General information
The MBE system is a materials research and development facility located at HCØ, owned by NBI/KU.
Our MBE lab is located on the 2nd floor in rooms 3-2-213A, 3-2-217 and 3-2-217A.
The system is a Varian GEN II with a 3" substrate capability. The III-V growth chamber has eight sources with the following materials.
| Group V | Group III | Dopants | Other |
|---|---|---|---|
|
As and Sb |
Ga, Al and In |
Si and Be |
Au |
The system also has a UHV metallization chamber attached equipped with a 6-pocket e-gun and a RF sputter source.
The principal investigator (PI) in charge of the NBI facility is Prof. Jesper Nygård.
Claus B. Sørensen is technical head of the lab.
MBE activities meetings
MBE activities and changes of procedures are discussed at open group meetings (typically the weekly MBE/Materials subgroup meeting at QDev) where the technical head is often present.
Access to the system
New users should be approved by the local management and must receive basic training by the technical head or a person appointed by the technical head before working on the system. Further, new users must have completed the cleanroom safety course before signing up for MBE training and gaining access to the MBE lab. The number of persons trained and allowed to use the MBE is limited in nature due to the complexity of operation.
Requests for cleanroom training must be mailed to cleanroom@nbi.ku.dk
Training
Requests for MBE training must be addressed to:
Jesper Nygård: nygard@nbi.ku.dk
Martin Saurbrey Bjergfelt: martin.bjergfelt@nbi.ku.dk
Access to room
Following completion of cleanroom and MBE training, access to the lab is granted by mailing your KU access card number and your contact details (mobile phone number and email) to:
Jesper Nygård: nygard@nbi.ku.dk
Martin Saurbrey Bjergfelt: martin.bjergfelt@nbi.ku.dk
Scheduling-Booking the system
All use of the system must be booked using the cleanroom tool booking page.
A system for handling project (alias) and planned growths (materials) may become effective in 2018 to facilitate planning and invoicing.
Cleanroom attire
Entering the MBE lab.
Please make sure that only one door in the airlock is open at a time to keep the room clean. The MBE room is an ISO 6/7 room and the prep-room is ISO 5/6.
- Before entering the gowning area: wear clogs
- Inside the gowning area you must put on the following:
- A cleanroom lab gown or a full cleanroom suit
- Hairnet
- Beard cover (if applicable)
Entering the preparation room
Before entering the preparation room, you must additionally: put on nitrile gloves
Safety
Oxygen depletion hazard
The MBE system is cooled by a closed loop liquid nitrogen system with a direct connection to the storage tank on the street. As nitrogen act as an asphyxiant, the oxygen level in the room is monitored to ensure that no risk of oxygen depletion can occur.
Should the oxygen level drop below the alarm value, the alarm will sound and flash.
You must evacuate the room immediately and notify Science Campus Service and one of the named staff members below.
Ensure that no one enters the room, block access!
If the alarm is active when you arrive, do not enter.
If needed, an emergency self-contained breathing apparatus is available on the 2nd floor on the wall across from room 03-2-214
Fire alarm
The MBE lab also has an early fire warning system if smoke is detected in the corridor on the second floor.
Should smoke be detected in the corridor, the alarm will sound and flash.
You must evacuate the room immediately and notify Science Campus Service and one of the named staff members below.
| Claus B. Sørensen | Nader Payami | Science Campus Service helpdesk |
|---|---|---|
|
Phone: 2875 0449 Mail: cbs@nbi.ku.dk |
Phone: 23 81 08 93 |
Phone: 3533 1333 |
Chemical and materials safety
All safety procedures in the cleanroom also applies in the MBE-lab. It is mandatory for users to familiarize themselves with the Materials Safety Data Sheets (MSDS) and observe good laboratory praxis.
Double gloving
Before starting to handle wafers, substrate holders or chemicals a second pair of nitrile gloves must be put on.
Wafers
Arsenic containing substrates must be handled using clean tweezers and kept in suitable wafer trays or boxes when taken out of the MBE lab. Wafer and sample storage outside of the cleanroom or MBE must be kept locked.
Full wafers and ready cut pieces are generally safe to handle when As containing dust particles are not generated.
When mounting and handling substrate holders the local point exhaust must be turned on and placed as close to the workplace as possible.
Fumehood
The fumehood must be used at all times when processing substrates (solvent cleaning, etching etch)
Contaminated and solid waste
All gloves, wipes, substrate pieces etc that are suspected to be contaminated or known to contain hazardous materials must be disposed of in the special risk waste bins.
Chemicals
Waste chemicals must be handled in a similar way as in the cleanroom using designated waste cans.
Logbook and system-traceability
As meticulous traceability is vital, all users must complete the MBE logs and store growth recipes on the dedicated data storage units. Further, a system for storing post-growth characterization data is under development (2018).
- Growth recipes should be stored in the MBE Molly control system
- Each growth is entered in the dedicated excel sheet on the MBE PC and the sheet is stored in a designated Dropbox
Materials
As MBE growth of semiconductors depends heavily on the cleanliness of the system, extreme caution must be paid to keeping the system clean.
Only materials and cleaning procedures approved must be used on substrates that are intended for use in the MBE system.
Prior to using any new materials or cleaning procedures on substrates these must be approved by the technical head.
The following substrates are approved in an Epi ready state:
GaAs, InAs, GaSb, InSb, InP and Si.
All substrates much be acquired from an approved, well-known source in high quality.
Processed substrates must be free of any organic contaminants and thoroughly cleaned by oxygen plasma ashing and HF dipping prior to loading. During degassing of processed substrates the massspectrum of the residual gasses must be observed both in the load lock and subsequent in the buffer chamber. If any sign of organic or other unwanted contaminants show up, degassing must be stopped immediately and the substrate unloaded.
Substrates have a long lead-time so please pay attention to the stock and give a heads up in good time before stock becomes low.
Operating the system
Cleanliness and vacuum integrity are key parameters for growing clean epi layers and attention must be paid to this at all times. Do not rush a sample through but wait for the chambers to reach the threshold vacuum values before transfer between chambers.
Service and maintenance
The users are no allowed to perform any maintenance or service on the system unless approved by the technical head.
The only chamber that users are allowed to vent is the Load lock chamber.
Problems and incidents
We encourage users to report all problems or incidents. Using a complex system like the MBE, will from time to time result in mistakes and unintentional incidents. We all learn from this and the best way to keep the system in a good operational state is to ask for help when needed!
Thus, should you experience any problems with the system, these must be reported to the technical head immediately.
In case of incidents including dropped or "hanging" sample holders please do not attempt to fix this but try to leave the system in a best possible safe state and report to the technical head.
Last revision: July 2018.