Pacific Nanotechnology Inc. - Printable version

Nano-DST™

Introduction

The Nano-DST™ is an advanced, high performance, Atomic Force Microscope designed for the most demanding research applications. This complete AFM system includes advanced control software, a high performance electronic controller, a versatile stage, and an available vibration solution. The system is constructed from the highest quality components assuring mimimal service repair and a long product lifetime.

Advanced features of the Nano-DST™ are:

Dual Scanner Control (DST): Two scanners can be driven individually or simultaneously in the Nano-DST™, to perform rapid scanning, panning, and achieve the highest resolution possible.

Modular Electronic Controller: Because the Nano- DST™ electronic controller is modular, it can be configured for an endless number of experiments and applications.

Flexure Scanner with 3-D Calibration Sensors: With the proprietary flexure scanner design, the most accurate and precise data is measurable with the Nano- DST™. Optional scan ranges as high as 350 microns are possible.

Advanced Specifications: 24 bit scan control as well as a 400 MHz, low noise, high stability modulation electronics assures the highest performance specifications available in an SPM system.

Designed for modes: With the Nano-DST™ all AFM modes may be implemented including SThM, MFM, EFM, STM, SKPM... Support is provided by Pacific Nanotechnology for customers that want to experiment with new modes.

Motorized Stage Control: The Nano-DST™ stage includes seven stepper motors that control the sample position, optics zoom, and focus. Z axis motion control, with 3 motors, facilitates rapid probe approach as well as enables control of the probe/sample angle. All motors are operated by our new high speed motor controller.

Nano-DST™ Stage

The Nano-DST™ stage is constructed with the highest quality precision granite that includes a base and a gantry. The entire video optical microscope and light lever AFM scanner are supported by the gantry. The stage is designed to maximize stability so that low noise measurements are possible. Additionally, the Nano-DST™ stage is very flexible to allow not only basic scanning but additional types of experiments.

Nano Flex™ Light Lever AFM (LL-AFM):

The LL-AFM scanner incorporates a high performance flexure scanner that gives superior scanning specifications including linearity, crosstalk, and bow. Combined with the XYZ calibration sensors, reliable and accurate measurements are possible. Probes are held in place with the magnetic probe holder for mounted probes. A clip mount is available for unmounted probes. Stray light is minimized with the tightly focused laser, which reduces unwanted artifacts in images. With the high bandwidth, four quadrant photo-detector, it is possible to make high frequency vibrating mode measurements as well as frictional force measurements. The scanner includes connectors for modes that require direct electrical contact to the probe.

High Speed Sample (HSS) Rapid Scanner:

A four-quadrant high-resonance tube scanner is provided for rapid scanning. The HSS rapid scanner is mounted in the Nano-DST™ stage below the LL-AFM scanner in a puck. It may be replaced with the mutilayer sample puck and/or environmental cell, or other sample holding option. The LL-AFM scanner may be used to “pan” over a sample while rapid scanning (see Figure 3).

Probe Exchange Mechanism:

Probe exchange in the Nano-DST™ is facilitated with the flip-up scanner mechanism. The mechanism is locked into place with two easy access locks at the front of the LL-AFM scanner. Combined with the automated stage and software, probe exchange takes only a few minutes. Because the scanner is always firmly attached to the stage, the scanner can not be accidentally damaged (see Figure 4).

Sample Puck:

A removable sample puck supports the sample while scanning with the LL-AFM scanner. The very flexible puck has several removable plates that allow samples of many thicknesses to be scanned. Samples may be held in place magnetically or with an adhesive tape. The puck may be readily replaced with an environmental cell, a rapid scanner, or even a sample heating stage (see Figure 5).

XY Positioning Stage:

Moving a sample relative to the AFM scanner is possible with the motorized XY translation mechanism. The automated stage is designed such that the sample holding puck is in direct mechanical contact with the granite base. High performance microcontroller electronics control the high resolution stepper motors in the stage. The stage motions may be activated by a track ball, mouse, or software algorithm. Under automation, step and repeat scanning is possible (see Figure 6).

Video Optical Microscope (VOM):

The Video Optical Microscope (VOM) in the Nano-DST™ is optimized for finding features for scanning, aligning the LL-AFM sensor, and facilitating probe approach. Both zoom and focus are under stepper motor control and can be adjusted with software controls. The objective of the VOM is a direct on axis view of the probe and sample. VOM images are digitized with a high resolution CCD camera and are displayed on a 19” LCD monitor that comes standard with the Nano-DST™ system (see Figure 7).

Z Motion Control:

Three independently operated motors control the relative motion between the LLAFM scanner and the sample. The motors are driven by microcontroller chips to assure the greatest accuracy when approaching the probe to the sample. Additionally, the angle between the probe and the sample may be adjusted with software to minimize image artifacts associated with non-perpendicular probe angles (see Figure 8).

Stage Signal Access Console (SSAC):

The Stage Signal Access Console (SSAC), located directly on the stage, allows access to the phase/amplitude detection, PID feedback, D/A output, and high voltage scanner control electronic signals. These outputs may be used for the rapid scanner or may be used for modes such as SKPM or SHARK (see Figure 9).

Controller

The Nano-DST™ electronic controller is the most advanced electronic controller for the control of an AFM. It includes all of the circuits required for controlling seven stepper motors as well as two piezolelectric scanners. The controller utilizes a Pentium IV microprocessor for computations and the controller software is written in C++ on a LINUX platform. Reliability is assured with the 16 bit and 24 bit DAC input output cards from National Instruments (see Figure 10).

Signals may be monitored with the Signal Access Console that connects to the rear of the electronic controller. All signals associated with the performance of the Nano-DST™ are available.

Control Computer/Software

A state of the art PC, optimized for AFM operation, is included with the Nano-DST™ system. Reliability is assured with computers configured by Dell™. The computer system includes ample disk drive capacity to store AFM images and to transfer them to a CD when desired. A 19” LCD monitor is also included.

The Nano-DST™ command and control software, derived from SPM Cockpit™, is in use in hundreds of laboratories throughout the world. The software operates in two modes:

• EZ Mode™ for beginners and casual users
• X’pert™ Mode for advanced AFM operators

Signals may be monitored with the Signal Access Console that connects to the rear of the electronic controller. All signals associated with the performance of the Nano-DST™ are available.

Environmental

Vibration Solution: The highest performance is assured when the optional acoustic enclosure and vibration table are used with the Nano-DST™.

System Options:

• STM
• Environmental Cell
• SHARK
• MFM
• EFM
• Kelvin Probe

System Options and Specifications

Light Lever AFM / Scanner

Force Sensor Light Lever

Detector 4 Quadrant Photo-detector

Laser 650 nm diode – 25 micron spot size

Laser Adjustment 80 TPI

Probe Holder Universal Adapter

Probe Types Pre-mounted - Magnetic

XYZ Calibration Sensors Inductive – 1 nm resolution

Z Scanner Type Piezoelectric Ceramic – Direct

Z Range 8 Microns

Z Noise <0.06 nm*

Z Linearity < 1 %

Z out of plane motion < +/- 30 nm

XY Scanner Type Flexure

XY Range 90 Microns(180 or 360 microns optional)

XY Linearity < 1 %

XY Noise < 0.01 nm (open loop)

XY, XZ, YZ Crosstalk < 1 %

Probe Electrical Connector Isolated 5 Connector

1624 Electronic Control

Primary Scan DAC 24 Bits

Secondary Scan DAC 16 Bits

XYZ board – Primary and Secondary
• Digital Zoom/Offset
• Analog Zoom
• Z High Voltage
• Z Sample/Hold
• PID Control
• Phase/Amplitude
• XY High Voltage
• XY Sensor Feedback 16 Bits
4 bits on High Voltage
-20 to 140 Volts
20 Bits
Analog
400 Mhz Clock/32 Bit Frequency Control
+X,-X +Y,-Y (-20 to 140 Volts)
Analog PID Control

User Access Connector for Signal Access Console

Internal Digital Control
• CPU
• Operating System
• Communications Protocol
• Memory Pentium
Linux
TCP/IP
RAM/Disk Drive

Motor Driver Board
• Number of Motor Drivers
• Motor Type
• Control
• Additional Function 7
Stepper
Microprocessor
Light Intensity Control

Stage

XY Stage Range
• X
• Y 50 mm
75 mm

XY Stage Step Size 2 um

XY Stage Accuracy < 10 um

Z Motor Range 8 mm

Z Motor Step Size 162 nm

Sample Puck
• Hold Down
• Height
• Maximum Sample Diameter Magnetic
30 mm
100 mm

Optical Microscope
• Resolution
• Zoom Ratio
• Field of View 1.5 u
4:1
140 ? 190 u at Maximum Zoom

Probe Exchange Flip Up

Physical Specifications

Width Depth Height Weight (kg)

• Stage
• Vibration Enclosure
• Electronic Controller
• Work Station

14 19 16 50

31 33 56 275

12 18 22 22

7 16 16 14

Rapid Scanner

Type Four Quadrant Tube

XY Range 2 Microns

XY Noise 0.1 nm

Z Range 500 nm

Z Noise 0.001nm

Scan Rate 250 Hz

Control Station

Computer Monitor 19” LCD

Video Monitor 19” LCD

Accessories Mouse, Keyboard, Trackball

Computer:
• Type
• Operating System
• Memory
• Disk Drive
AFM Software:
• Acquisition
• Display
Video Converter
IBM PC
Microsoft Vista
> 1 Gigabyte
> 200 G Bytes

EZ Mode™, X’ert™ Mode
AFM Analysis, and NanoRule+™
NTSC – SVGA

Vibration Control (Recommended)

Acoustic Shield Herzan AEK-2002 Enclosure

Vibration Table Herzan TS-150 Active Isolation System