NPGS is the top selling SEM lithography system at research institutions in North America, and its use is becoming widespread around the world. The objective for NPGS is to provide a powerful, versatile, and easy to use system for doing advanced beam or ion beam lithography using a commercial SEM, STEM, FIB, or dual beam (SEM/FIB) microscope. The success of NPGS at meeting this goal is demonstrated by the strong recommendations from current users.

Application
SEM lithography can be used for the fabrication of a wide variety of devices. Research areas include: quantum structures, such as single electron transistors; optical structures, such as binary holograms and linear/circular gratings; electro-mechanical structures, such as Surface Acoustic Wave (SAW) and MEMS devices; as well as the testing of novel resists and ultra-small sensor fabrication.

Pattern sizes may range from the nanometer scale up to the maximum field of view of the microscope, which can be as large as 10 mm. However, as on any SEM lithography system, the writing resolution will decrease as the field size is increased.

Sample Pictures



Low-kV(2kV and 5kV) E-Beam Lithography-for sensitive substrate application.
The samples were fabricated using FEI Inspect F by Bruce Ou in Taiwan.

Low-Vacuum E-Beam Lithography
The patterns were no distortion on LiNbO3 substrate in low-vacuum lithography with charging reduction by gaseous process. Moreover, the dot array of 50nm diameter and 200nm pitch has been fabricated. The nanostructure on non-conducted materials can be realized by low-vacuum lithography.

The samples were fabricated using FEI Nova NanoSEM by Bruce Ou in Taiwan.

Si based Photonic crystals fabricated by ICP RIE Etching in conjunction with EBL.
This work was supported by Dr. Wu’s group in NCUE, Taiwan.


Photonic crystals were made by E-Beam lithography and ICP RIE. This work was done by Dr. Min-Hsiung Shih at the Research Center for Applied Sciences of Academia Sinica in Taiwan
.
This picture shows a double bend in a split-gate field-effect transistor. The substrate consists of MBE grown AlGaAs on undoped GaAs. Even though the width of the gap is only 100 nm, notice how the corners are quite sharp. - Pattern written by Dr. J.C. Wu while at University of Oregon.  He is now at National Chang-Hua University, Taiwan.

• Analog XY Inputs; +/-3v to +/-10v range typical, other ranges can be supported; >5k ohms impedance typical, >2k ohm is supported.
• Picoammeter; A picoammeter that can read the beam current hitting the sample is required for lithography. Typically, an external picoammeter is connected to the specimen current output from the microscope stage, or less often, a picoammeter will be built into the microscope. In either case, the picoammeter is usually not directly connect to NPGS, although it can be through a optional interface.

• Image Signal; within +/-10v; used for NPGS Alignment feature.
• Blanker; within +/-5v, <200 mA; fast blankers, slow shutters, and systems with no blankers are all supported.

Optional Connections (dashed arrows)

• Automated Stage; interface programs for several common automated stages are available at no charge. Any automated stage can be supported, if the serial interface protocol is available.
• Digital Microscope Control; interface programs for several common digital microscopes are available at no charge. Any digital microscope can be supported, if the serial interface protocol is available.
• Faraday Cup & Picoammeter; NPGS can optionally be connected to control a Faraday cup and/or read from a picoammeter, but most systems will have a manually controlled Faraday cup and picoammeter.

Software

• NPGS - Version 9.0
• DesignCAD Express v16.2 or higher

Hardware

• High speed (5 MHz, optional to 6 MHz), 16 Bit, high resolution (0.25%) PCI516 lithography board.
• Cables to connect NPGS to microscope.
• Optional relay or switch to share microscope input with another accessory, typically an EDX system.
• Pentium IV 3.0 GHz computer (or better) with:
• 512 Mb RAM, 80 Gb Hard Disk, CDRW Drive.
• 17" LCD Monitor.
• Wheel Mouse, LAN, USB, Serial, Parallel.

NPGS Training

• Optional on-site user training

The user must supply

• SEM, STEM, FIB, or dual* SEM/FIB with:
• XY External Scan Control Input (within +/- 3 to +/- 10 volts, >2k ohms).
• Image Signal Output (within +/- 10 volts).
• Picoammeter for Measuring Beam Current (0.1 pA resolution or better; typically Keithley 6485).
• *A dual SEM/FIB can have both beams controlled by NPGS, but only one at a time where either a software or hardware switch (depending on microscope model) will select the writing mode.

Recommended

• Beam Blanker with rise/fall times <1 usec (digital input within +/- 5 v and <200 mA).
• (Slow Beam Shutter or no blanker will also work).
• Fine Z stage control to ~1um.
• Faraday Cup (apertures to make cup are included with NPGS).
• Scan Rotation Option.
• Gold on Carbon SEM standard mounted on sample holder.
• Stray AC less than 3x10-7 Tesla(p-p); Magnetic shielding for chamber or active field cancelling system can reduce interference.
• Vibration less than 2x10-6 meters(p-p) over 5 Hz.

Microscope Models that have been used with NPGS:

Almost any SEM or STEM can be used with NPGS to perform e-beam lithography. The following is an alphabetical list of the microscopes that have been used with NPGS. Note that some models require optional external inputs from the manufacturer. Often, different models of microscopes from the same manufacturer will have the identical XY interface. Consequently, models that are not shown, may actually be the same as a model already in use with NPGS. Please call or send e-mail if you would like to get the complete NPGS User List which includes names, telephone/fax numbers, e-mail addresses, and microscopes being used. (The models shown below are indicated as: SEM=Scanning Electron Microscope, STEM=Scanning Transmission Electron Microscope, FE-SEM=Schottky (thermal) Field Emission SEM, and cFE-SEM=cold cathode FE-SEM.)

• Amray 1200, 1400, 1830 SEMs
• Amray 1845 FE-SEM
• Cambridge Instruments S120, S200, S240, S250, S360 SEMs
• Camscan Series 4 SEM
• Elionix ERA-8800
• FEI XL30 LaB6 SEM
• FEI XL30 FEG, XL30 SFEG FE-SEMs
• FEI XL30 ESEM FEG FE-SEM
• FEI Inspect S & Quanta SEMs
• FEI Inspect F, Quanta FEG, & FEG ESEM FE-SEMs
• FEI Sirion & NanoSEM FE-SEM
• FEI Strata 235/620, Quanta 3D, Nova Nanolab , & Helios Dual FE & Ion Beam Microscope
• Hitachi S510, S570 SEMs
• Hitachi S2460N SEM
• Hitachi S2300, S2500 Delta, S2700 SEMs
• Hitachi S3000H, S3000N, S3400, S3500N SEMs
• Hitachi S4100, S4200, S4700, S4800 cFE-SEMs
• Hitachi S4300SE FE-SEM
• Hitachi SU-70 FE-SEM
• Hitachi FB2000A FIB
• ISI 60 SEM
• JEOL 1200EX STEM
• JEOL 820, 840, 845, 848 SEMs
• JEOL 5400, 5600, 5800, 5900, 5910, 5910LV, 6360, 6460 , 6380, 6480, 6390, 6490 SEMs
• JEOL 6100, 6300, 6400, 6600 SEMs
• JEOL 840F, 6300F, 6340F, 6400F, 7401F cFE-SEMs
• JEOL 6500F, 7000F, 7001F FE-SEMs
• Leica S440 SEM
• LEO S438, S440 SEMs
• LEO 1430, 1430VP SEMs
• LEO 982, 1525, 1530, 1530VP, 1550 FE-SEMs
• Philips 501 SEM
• Philips EM420 STEM
• Philips CM-20 STEM
• Philips XL-20, XL-30 SEMs
• Tescan Vega SEM
• Topcon SM 350 SEM
• Zeiss 940A , 960A SEM
• Zeiss EVO SEM
• Zeiss/LEO Supra, Supra VP, Ultra FE-SEMs
• Zeiss/LEO Crossbeam 1540 Dual FE & Ion Beam Microscope

Notes: Cambridge Instruments became Leica, which merged with Zeiss to become LEO, which has now changed to Carl Zeiss - Nano Technology Systems; Philips became FEI; The FEI "Sirion" is almost identical to the FEI XL30 SFEG model; The FEI NanoSEM & Quanta FEG models uses the same FE column as the Sirion; The Zeiss/LEO "Supra" is almost identical to the LEO 1500 series; The JEOL 7001F/7000F is almost identical to the JEOL 6500F.