Specific Process Knowledge/Characterization/SEM Gemini 1

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The SEM Gemini 1 being installed in the cleanroom. Photo: DTU Nanolab internal

DTU Nanolab introduces next-generation SEM in the cleanroom

Right now, we are installing a new field emission scanning electron microscope (FE-SEM) in the B-section of the cleanroom. It is a state-of-the-art GeminiSEM 560 with the new Gemini 3 column from Carl Zeiss. The tool is next-generation compared to our present three about 10 years old Supra-40/60 SEM’s (also from Carl Zeiss). We are looking forward to offer our users access to all the new features provided by this tool, a.o.:

Detectors:

• SE2: Chamber mounted secondary electron (SE) detector
• In-lens SE: In-column high resolution SE detector
• In-lens EsB: In-column highly sensitive backscatter electron (BSE) detector for obtaining good material contrast
• aBSD: Retractable column mounted solid state BSE detector with six sectors for detection of energy and angle selective backscattered electrons, i.e. for obtaining both material and topographical contrast
• VPSE: Variable pressure (VP) light detector for SE signal detecting
• aSTEM: Retractable solid state STEM detector with five sectors enabling bright field and both annular and oriented dark-field transmission electron imaging

Dramatically improved performance on insulating samples achieved via two pathways:

• Latest generation column design that takes low kV imaging to the next level
• Sophisticated low vacuum modes for charge compensation:
• Standard variable pressure (VP)
• NanoVP: A retractable differential pumping aperture mounted on the column makes it possible to use the In-lens SE and ESB detectors in VP mode

Other features:

• Installed on an actively damped anti-vibration platform and with magnetic field cancellation system to protect it from external sources of noise
• Sample bias option and dedicated sample holders
• Plasma cleaner for in-situ sample and chamber cleaning
• Sample loading trough a load lock or the chamber door
• Load lock mounted camera for easy sample navigation
• Several new automated features

We will spend the coming weeks on the installation and acceptance tests of the tool and prepare the training protocol. We hope that you will receive the tool well when we release it, which we expect to do in September.

SEM Gemini 1

The SEM Gemini 1 is a scanning electron microscope (SEM). It is a Zeiss GeminiSEM 560 .

The SEM produces enlarged images of a variety of specimens, achieving magnifications of over 500.000x providing ultra high resolution imaging. This important and widely used analytical tool provides exceptional resolution and depth of field and requires minimal specimen preparation.

The SEM is equipped with six different detectors:

• SE2: Chamber mounted secondary electron (SE) detector
• Inlens SE: In-column high resolution SE detector
• In-lens EsB: In-column highly sensitive backscatter electron (BSE) detector for obtaining good material contrast
• aBSD: Retractable column mounted solid state BSE detector with six sectors for detection of energy and angle selective backscattered electrons, i.e. for obtaining both material and topographical contrast
• VPSE: Variable pressure (VP) light detector for SE signal detecting
• aSTEM: Retractable solid state STEM detector with five sectors enabling bright field and both annular and oriented dark-field transmission electron imaging

The SEM is a VP (variable pressure) instrument, indicating that it is capable of operating at variable pressure. By increasing the pressure in the chamber it is possible to image isolating samples. The higher density of gas molecules will eliminate the charges at the cost of slightly reduced resolution. It has two different VP modes: A standard VP mode like the SEM Supra 1, 2 and 3 and a NanoVP mode. In the standard VP mode, the pressure in the chamber is increased as described above, and the dedicated VPSE detectors or the aBSED detector is used to image charging samples. In Nano VP mode, an retractable beam sleeve aperture is mounted on the column, which makes is possible to use the Inlens SE and the Inlens BSE detectors to obtains high resolution images of non-conducting samples. The SE2 and sSTEM detectors will not work in VP mode.

The SEM Gemini 1 is located in the cleanroom. It is being installed and tested in August-September 2023.

The user manual, control instruction, the user APV and contact information can be found in LabManager:

SEM Supra 3 info page in LabManager,

Performance information

• SEM comparison page

Equipment performance

Equipment		SEM Supra 3 (Supra 40VP SEM)
Purpose	Imaging and measurement of	Conducting samples Semi-conducting samples Thin (~ 5 µm <) layers of non-conducting materials such as polymers Thick polymers, glass or quartz samples
Location		Cleanroom of DTU Nanolab
Performance	Resolution	1-2 nm (limited by vibrations) The resolution is strongly dependent on the type of sample and the skills of the operator.
Instrument specifics	Detectors	Secondary electron (Se2) Inlens secondary electron (Inlens) High Definition four quadrant Angular Selective Backscattered electron detector (HDAsB) Variable pressure secondary electron (VPSE)
	Stage	X, Y: 130 × 130 mm T: -4 to 70o R: 360o Z: 50 mm
	Electron source	FEG (Field Emission Gun) source
	Operating pressures	Fixed at High vacuum (2 × 10-4mbar - 10-6mbar) Variable at Low vacuum (0.1 mbar - 2 mbar)
	Options	High Definition four quadrant Angular Selective Backscattered electron detector (HDAsB)
Substrates	Batch size	Up to 6" wafer with full view
	Allowed materials	Any standard cleanroom material

Quality control of length measurement

Quality Control (QC) for SEM Supra 3

QC procedure for SEM Supra 3 Newest QC data for SEM Supra 3 QC limits: Detector Settings Magnification Measured dimensions Calibration limit Action limit SE2 EHT 10 kV, WD 10 mm 2.440 k (mag range 1) 70x70 μm ± 2 % ± 3 % SE2 EHT 10 kV, WD 10 mm 17.000 k (mag range 2) 10x10 μm ± 2 % ± 3 % SE2 EHT 5 kV, WD 5 mm 17.000 k 10x10 μm ± 2 % ± 3 % InLens EHT 2 kV, WD minimum 17.000 k 10x10 μm ± 2 % ± 3 % HDAsB (Compo) EHT 10 kV, WD 5 mm 17.000 k 10x10 μm ± 2 % ± 3 % VPSE EHT 10 kV, WD 10 mm, 17 Pa 17.000 k 10x10 μm ± 2 % ± 3 % InLens EHT 5 kV, WD 5 mm 200.000 k (mag range 3) 1x1 μm ± 2 % ± 3 % InLens EHT 10 kV, WD 3 mm 1.000.000 k (imaging only) NA NA