SEM_specifications_final3.docx

Specifications for a Variable Pressure (VP) Field Emission Scanning Electron Microscope (FESEM)

GENERAL

Below are specifications for a variable pressure (allowing for imaging of low conductivity specimens without coating), high resolution, field emission scanning electron microscope (FESEM). The contractor shall work with the company contracted to supply an x-ray energy dispersive spectroscopy (EDS) and electron back-scatter diffraction (EBSD) through a concurrent procurement.

Item 1. (required) The Contractor shall provide a scanning electron microscope (SEM) which shall have the following features and capabilities:

Item 1A. Vacuum System

1. The vacuum in the specimen chamber, electron source, and microscope column must be maintained by an oil-free pump. Vacuum surfaces and components in the vicinity of the electron beam shall not be subject to degassing or degradation under electron or x-ray radiation.

2. A column vacuum of less than 10-6 Pa and FEG gun vacuum of less than 10-7 Pa must be maintained, with partial pressures of hydrocarbons less than 4 x 10-8 Pa and of water vapor less than 8 x 10-6 Pa.

3. If, in standard operation upon the introduction of a new specimen, it requires more than 4 minutes to pump down the specimen chamber to a high vacuum operating pressure, a specimen exchange air-lock shall be included. If included, the air-lock shall be completely integrated with the automatic safety interlocks. The airlock shall accommodate sample holders/samples up to a minimum of 45 mm in diameter by 20 mm z-axis. Airlock shall be pumped to specified pressure, not for set amount of time, for fast evacuation and fail-safe operation.

4. The vacuum system shall be capable of providing user selectable stable specimen chamber operating pressures ranging from high vacuum (10-3 Pa or lower) up to 500 Pa. Readouts of column and specimen chamber pressure values shall be present.

5. The vacuum system shall be fully automated under computer control and shall be completely fail safe in case of power failure or loss of cooling. There shall be system protection for power, cooling, or vacuum failures.

Item 1B: Specimen Chamber

1. The system shall include a specimen chamber large enough to accommodate specimens of at least 120 mm in diameter and at least 85 mm in height.

2. The chamber shall have a minimum of 12 ports for current devices and/or future needs.

3. Specimen chamber shall have a dedicated port optimized for an x-ray silicon drift detector with a minimum 35 degree take off angle on a zero degree tilted sample.

4. Specimen chamber shall have a port optimized for electron back scattered diffraction (EBSD) allowing simultaneous collection of EBSD and x-ray spectra.

5. The chamber shall be equipped with an infrared camera and light source sufficient for observation of sample movements to help prevent collision with system components.

6. It is highly desirable that the system be equipped with the ability to easily navigate and find desired mount locations. This can be either via a ‘navigation camera’ where an optical image of the holder and mount can be acquired and then used for on-screen navigation to desired mount locations, or through the inherent ability of the system to show magnification views of the stage 1x or less.

7. Specimen chamber design shall include a system to minimize the effect of externally imposed vibrations on the microscope. Active vibration isolation would be highly desirable.

Item 1C. Specimen Positioning Stage

1. The positioning stage shall be controlled via software and/or a dedicated controller (e.g., joystick), shall have 5 independent degrees of freedom (X, Y, Z, rotation, and tilt), allow for compucentric specimen positioning, full 360° of rotation, -15° to +90° tilt range or more, X/Y travel of 100 mm or more, and Z travel of 65 mm or more. Minimum step size in X, Y, Z shall be 0.1 um or less. X, Y, Z repeatability shall be 1.0 um or less. Tilt accuracy and repeatability shall be better than 1 degree.

2. Touch or proximity sensors (with an alarm) and software limits shall be incorporated into the stage design to immediately stop all movement in case the stage, or the specimen, comes in contact with something in the chamber.

3. At a magnification of 100kx (or higher if possible), the specimen stage shall have sufficient stability show no perceptible image wobble.

4. The stage shall accommodate specimens weighing as much as 500 grams or more. It is highly desirable that the stage accommodate specimens weighing as much as 5 kg or more.

5. Stage shall be equipped with an integrated specimen current monitor.

6. The software shall allow for navigation by clicking the mouse cursor on the area of interest. This area shall then automatically be brought to the center of the screen by the instrument, using either beam shift or stage movement, whichever is necessary.

7. The stage Z (vertical) motion shall be continuously adjustable (via software control and preferably a dedicated control) allowing the image to be focused by raising or lowering the sample in the chamber until it coincides with the electron beam crossover.

8. It is highly preferred that the system shall include multiple sample holders compatible with the stage OR a standard multipurpose holder. Examples include but are not limited to:

a. Single stub holder.

b. Carousel 9x sample holder.

c. Eight position quick-fit carousel for 13 mm diameter pin-type stubs.

d. Vise sample holder to clamp irregular samples.

Item 1D. Electron Source

1. The electron column vacuum system shall be computer controlled for fully automated operation and fully integrated with the sample vacuum chamber. The column should be isolated during specimen exchanges.

2. A factory aligned field emission gun (FEG) with high stability, brightness, and temporal coherence must be included. It should have its own vacuum system (typically an ion pump) and shall have an automated column isolation valve. Available probe current at 30kV should be ≥ 200 nA.

3. The emitter shall have an average stable lifetime 1700 hours or more.

4. The electron source/column shall provide a beam current stability better than 0.2% / hour.

Item 1E: Electron column

1. The electron source/column shall provide a secondary electron image resolution measured as gold particle separation on a carbon substrate of 1.0 nm (or smaller) at 15 kV and at 1.0 nm (or smaller) at 1 kV. The guaranteed resolution specifications quoted, shall be demonstrable throughout its lifetime, especially after replacement and conditioning of the emitter source.

2. The scanning system in the column shall provide for user selectable magnifications from 30x to 500,000x (a larger range is acceptable).

3. Range of accelerating voltages shall be to a maximum of 30kV and a minimum of 200V or lower with continuous control in selectable step sizes. There shall be no restriction in sequence of any parameter change, i.e., no accelerating voltage change, regardless of the breath or direction of the change, shall endanger the system's stability or increase the possibility of a failure. No more than one minute shall elapse to stable operation upon changing the accelerating voltage.

4. The electron column shall have focus wobbler with variable amplitude.

5. The system shall have scan rotation, dynamic focus, and tilt correction.

6. The system shall allow for user positioned adjustable reduced scan and spot mode.

7. The system shall be capable of imaging and analyzing magnetic samples with minimal degradation in resolution.

8. The electron beam shall be automatically diverted from the specimen whenever a live image is not being displayed for inherently low dose conditions and beam sensitive sample protection.

Item 1F: Imaging modes (electron detectors)

1. The system shall include an Everhart-Thornley secondary electron detector.

2. The system shall include an in-lens secondary electron detector.

3. The system shall include a dedicated, retractable, backscattered electron (BSE) detector that inserted and retracted either manually or via a computer controlled actuator. It shall be possible to introduce, at a user-selectable level, a high-resolution backscattered electron image signal to enhance the secondary electron imaging with compositional information and contrast. A simple GUI control shall allow for either real-time adjustment of the ratio of BSE:SE signal. The system shall include a dedicated solid-state backscatter electron detector configured for maximum sensitivity to low energy electrons. Operation of the backscattered electron signal shall be integrated and controlled within the system’s software, allowing the user to define the compositional and topographical response of the detector. The backscattered electron detector shall not interfere with collection of x-ray spectra with an x-ray detector positioned in the standard location or EBSD patterns when inserted or retracted. The BSE detector shall allow imaging at accelerating voltages of 1 to 30 kV.

4. In-column BSE detectors may be included. In-column BSE detectors shall be optimized for small working distance imaging (providing compositional, topographical, and surface elemental contrast).

5. The system shall have a configuration optimized for high resolution imaging for beam sensitive materials. This can be achieved through a beam deceleration mode, low voltage/current fast scanning with frame averaging, charge filtering, or low-vacuum imaging, etc.

6. The system shall be capable of acquiring up to 4096 by 4096 pixel resolution (or more), 16 bit grayscale images with, user selectable resolutions lower than this to allow trading off speed of acquisition for image size (resolution).

Item 1G. Computer and Software

1. Microscope control (stage position and column settings) and all image acquisition shall be performed by an integrated software system.

2. The control computer and monitor (monitor shall have at least 24” diagonal measurement) shall be provided.

3. The control computer shall be equipped with a minimum of 8 GB of RAM and a minimum 500GB hard drive.

4. The microscope software platform shall be based on the 64-bit Microsoft Windows 7 (or later version) operating system. It shall be user friendly and capable of fast acquisition and analysis of the acquired images and data.

5. The software shall allow for the automation of the acquisition and the analysis of SEM data. It shall also allow for the storage and recall of column settings and stage positions.

6. The software shall allow for image montages through the use of automatic stage positioning in user defined patterns. The software shall include the ability to seamlessly assemble the images into a coherent whole.

7. The software shall allow for the creation of anaglyphs (pseudo 3D images generated by specimen tilt and/or beam tilt). It is highly desirable that live 3D scanning and stereo imaging is available.

8. The software shall provide a facility to accurately measure and annotate distances and angles for all acquired images.

9. The system software shall include a facility to log system events (start-up, shut-down, errors, warnings, user login/out, etc.) that can be monitored by users with administrative privileges.

10. It is highly desirable that the communication with the microscope electronics be via an Ethernet connection to protect against expensive future upgrades (proprietary communication interfaces are highly undesirable).

11. It is highly desirable that all future software updates and upgrades be included for the life of the system.

Item 1H. Installation and Training

1. The contractor shall furnish all labor, material, tools, transportation, and lodging for installation and will provide a list of installation site requirements.

2. If necessary, the contractor shall supply an air compressor to meet the SEM's requirements.

3. If necessary, the contractor shall provide a water cooled water chiller.

4. The contractor shall provide a warranty of a minimum of twelve months.

5. The contractor shall provide operation and software manuals including electrical and mechanical drawings.

6. The contractor shall demonstrate system performance meets all specifications.

7. The contractor shall provide training (a minimum of sixteen (16) hours of on-site training) and demonstrate required performance.

8. It is highly desirable that the contractor directly provide service for all system components: SEM, all detectors, associated electronics and software, pumps, and chiller. This would preclude the need for multiple service contracts/contacts for subsequent system maintenance.

9. Contractor shall include a quotation of the service contract cost for the first 5 years of ownership.