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Photolithography
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Photolithography provides a useful tool for producing structures consisting of micron-sized features. This can be done on a variety of different substrates with relative ease. |
GCA AutoStep 200
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We are equipped with a GCA Autostep 200 5x
reduction step and repeat photolithography system. This tool
is capable of exposing features down to 400 nm over a 15 mm
square field. Substrates with a diameter of 100 mm can be automatically
loaded and aligned. Substrates of 10 mm, 75 mm, 150 mm and
200 mm can be loaded manually. A precise alignment system is
included to provide overlay of less than 100 nm. |
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| Control Panel | Inside the GCA AutoStep 200 |
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YES Ovens |
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| We are equipped with two Yield Engineering Systems ovens. The vacuum bake/vapor prime oven provides for pre-programmed dehydration and vapor deposition of a priming agent. The image reversal oven enables clean liftoff pattern transfer using virtually any positive tone photoresist. | |
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Vacuum Bake/Vapor Prime and Image Reversal Ovens |
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Karl Suss MA6 Contact Aligner
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The Karl Suss MA6 is a top and bottom side contact lithography printer used for fine line lithography and is capable of sub-micron printing resolution. |
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| Current setup and features include: | |
The ability to handle 100 mm diameter wafers. |
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The mask sizes required are either 6- or 7-inch. Future upgrades
will enable it to handle 5-inch photoplates. |
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Top side wafer alignment (TSA) using a conventional microscope,
wafer and mask stage assemblies. |
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Bottom side alignment (BSA) using bottom viewing optics, CCD
imaging with image frame grabber and TV monitor.
This allows registration of features on the backside of a wafer
to the topside of the same wafer (e.g. through
wafer etching, backside window etching for membrane
formation, back side masks for wafer-wafer bond alignment, etc.). |
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Automatic computer control with LCD status for User prompting
and keypad entry. Up to 100 programs may be
stored with five on line at any one time. Each program may be
edited for key parameters pertinent to the
lithography mode. |
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Fast or slow scanning of mask/substrate with a memory toggle
to quickly view between two locations is also
available. This makes alignment using one objective easier. |
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1000 watt mercury arc lamp with "smart power supply"
capable of operating in constant power mode,
or constant intensity mode. The default is constant intensity
mode. In the constant intensity mode, as the
lamp deteriorates, the power is automatically adjusted to keep
the intensity of the wavelength. Also, the intensity of the lamp
may be read from the power supply during exposure
or during a lamp test. |
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Choose from five different lithography exposure modes. These
include: soft contact, hard contact, vacuum
contact, low vacuum contact, and proximity. Each mode is easily
selected by keypad and may have certain parameters
changed by the user. |
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Reynoldstech Photolithography Hood
| This laminar flow hood features a Reynoldstech spincoater capable of handling substrates up to 6" in diameter. Spin speeds can be programmed in from 200-6000 rpm in recipes containing up to 10 steps. A heated tankof n-methyl pyrrolidone is also provided in this hood for stripping resist from wafers. A basin sink is also included. |
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| Reynoldstech Photolithography Hood |
Dry Etching
 Technics Turbo 810 RIE |
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Technics Turbo 810 RIE |
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Reactive ion etching (RIE) is a powerful tool for fabricating structures on the micro- and nanoscale. It offers unparalleled dimensional control of etched features and can be used to process a variety of materials including insulators, conductors, semiconductors and polymers. Halogen-based gasses are typically used in RIE processes; we operate both F2 and Cl 2-based processes in our lab. A Technics Turbo 810 RIE is used for general purpose F2-based processing. This system uses mixtures of CHF3, CF4, SF6 and O2 to etch, Si, Si3, N4, SiO2, refractory metals and polymers. |
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Trion Technologies Oracle
| A Trion Technologies Oracle cluster tool with a F2-based ICP deep RIE chamber and a Cl2 RIE chamber is used to etch a wider range of materials. This system has two separate chambers connected by a common load lock to alleviate cross contamination concerns. The F2 ICP chamber uses the same gas mixtures as the Technics RIE and can achieve very high etch rates of the same materials. The Cl2 chamber runs processes with Cl2, BCl3, SF6 and O 2 gasses and is used primarily for etching Si, GaAs, Al and Cr. |
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| Trion Technologies Oracle |
Plasma Deposition
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Trion Technologies Orion |
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| Deposited dielectric and semiconductor layers play an important role in the fabrication of micro- and nanostructures. We currently operate a Trion Technologies Orion plasma enhanced chemical vapor deposition (PECVD) system. This tool is capable of depositing uniform layers of SiO2, low stress Si3N4 and amorphous Si at deposition temperatures ranging from room ambient to 600° C. | ||
| Trion Technologies Orion | ||
PECVD Carbon Nanofiber Growth Facility
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Our PECVD system for VACNF growth consists of a glass bell-jar pumped by a diffusion and a mechanical pump. A resistive heater equipped with a temperature-control unit is mounted inside the chamber. For VACNF growth the samples are placed directly on to the heater plate and the plasma is created between a stainless steal rod anode and the heater (cathode). A typical DC plasma power of ~ 50-60 W is currently used. However, a much higher power up to 1200W can be obtained with our current power supply. A manifold with three gas lines is located next to the chamber and allows for independent control of the three gas components required for PECVD growth of VACNFs: (i) a carbon source (carbonaceous gas, e.g., acetylene), (ii) an etchant (e.g., ammonia), and (iii) a buffer gas, if needed. |
Thermal Oxidation
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One of the primary reasons why Si has remained the dominant material in semiconductor device fabrication is it's ability to grow a stable oxide that has excellent dielectric properties. We currently operate a Tempress tube furnace that can handle up to 3" wafers. This system can run a variety of thermal oxidation processes for Si that can reproducibly yield layers with thicknesses ranging from 50 A to 2 µm. |
Ion Beam Assisted Deposition (IBAD) Facility
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The IBAD facility is produced commercially by Ion-Tech and can be used either for completely automated film deposition or ion milling after a sample is loaded manually. The 350 liter vacuum chamber houses two Kaufman sources, with provisions for a third, and achieves a base pressure of 10-7 torr by employing a 2200 l/s turbomolecular pump. In normal operation, the 5cm source is used to sputter material from a double-sided paddle onto which 100mm diameter sputtering targets have been affixed. The sputtered material is directed at a 150mm substrate station having two degrees of freedom: Azimuthal rotation, to promote processing uniformity, and angular tilt, to alter the assisting beam's angle of incidence. When circumstances require a textured film or perhaps large area ion milling, the 15cm source is employed. This source faces the substrate and can be used to generate a 15cm Ar ion assisting beam having a few mA/cm2 with an energy of a few hundred eV to 2000eV. |
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 Ion Beam System |
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| Both sources employ beam neutralization schemes to avoid substrate and target charging, and to minimize beam divergence, but they are implemented in different fashions. The smaller source utilizes a simple immersed filament, while the larger uses a plasma bridge neutralizer (PBN). Although the initial cost of the PBN is higher than that of the immersed filament system, this unique system has a longer filament lifetime, it resides outside of the ion beam and thus prevents contamination, and it emits no optical or thermal radiation that may damage a substrate. In either case, the (neutral) ion beams in the IBAD facility can be used for processing most any material, including insulators, semiconductors, and conductors, although great care must be exercised with conductors. | |
| Typical processing pressures in this facility are on the order of 10-4 torr Ar, with partial pressures of oxygen in the vacuum chamber being allowed, but not recommended to exceed mid 10-5 torr. The instrumentation and gas handling facilities on this system do allow for some variation in the plasma constituents, but operation on 100% oxygen is not recommended with any of the sources because of the presence of filaments and other components susceptible to extreme oxidation. | |
Physical Vapor Deposition (evaporation)
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The deposition of thin films can be performed in a variety of ways. Physical vapor deposition (PVD), also known as evaporation is one of the most commonly used techniques due to its simplicity. Electron beam evaporation offers great flexibility as it allows the deposition of any metal and some alloys and insulating compounds. We currently have two electron beam evaporation systems both equipped with rotary sources that allow for the deposition of up to four materials in a single run. These systems constitute our primary means of depositing metallic thin films but can also be used to put down layers of SiOx and metal-based oxides. |
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| Electron Gun PVD |
Metrology Equipment
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In order to monitor the progress of samples during fabrication it is necessary to use various types of metrology tools. Our primary means of inspection during the microfabrication process is optical microscopy. |
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| Our clean room is equipped with a Leitz Ergolux microscope that is capable of imaging at magnifications up to 2500x. This microscope is also capable of dark field imaging up to 1000x and has an Electro Image Tri-Pix color CCD digital camera for image capture. | |
| Leitz Ergolux Optical Microscope |
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Thickness and optical constants (n and k) are measured with
a Filmeterics F20 Advanced Thin-Film Measurement System. Spectral
analysis of reflectance from the top and bottom of the thin
film quickly provides thickness, refractive index, and extinction
coefficient. Virtually any smooth, translucent, or lightly
absorbing film can be measured, including most dielectrics
and semiconductors. For measurements on patterned or non-uniform surfaces and other applications that require a spot size as small as 10 microns, we use a Filmetrics F40 Thin-Film Thickness Measuring Tool. The F40 is attached to our microscope and combines spectral reflectance, advanced analysis software, and a c-mount for a CCD camera. |
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| Filmetrics F20
and F40 attached to a Leitz Ergolux Optical Microscope |
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Single layer transparent film stacks can be measured using our Rudolph FTM. This instrument is a noncontact, interferometry based-measurement tool that provides a quick assessment of layer thickness; it is particularly useful for characterizing photoresist. |
KLA Tencor Alpha-Step 500 Surface Profiler
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Profilometry is another very useful metrology tool commonly used in micro-and nanofabrication labs. We use a Dektak IIa profilometer in our lab to provide accurate information on the topology of large sample features (>100 nm). Also utilized is the KLA Tencor Alpha-Step 500 Surface Profiler. |
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| KLA Tencor Alpha-Step 500 Surface Profiler | ||
Thin Film Miscellaneous Processing
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| Chemical mechanical polishing (CMP) is a technique used to planarize surface topography. Our facility includes a Strasbaugh 6EC CMP tool capable of handling whole 3”, 4”, and 6” diameter substrates. This system can be used to planarize silicon and silicon dioxide thin films as well as polymers and other dielectrics and conductors. Surface roughnesses less than 1 nm can be achieved. | ||
| Strasbaugh 6EC CMP |
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| The dicing saw is used to cut finished substrates into individual die. It can be used with substrates as small as 1 cm2 up to 6" in diameter. Substrates must also be less than 1 mm thick. This tool can function in either an automatic or manual mode where single pass cuts can be achieved. All alignment to the substrate is performed by a split field video stereo microscope. | ||
| Disco Dad/2H6T Dicing Saw |
Electrical Testing
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Signatone Probe Station |
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| Two manual probe stations are currently available to assist in the electrical testing of samples. Both systems are contained in enclosures that can be optically sealed for photo sensitive measurements. One system features a temperature controlled chuck that can be heated to 300° C without interfering with sensitive electrical measurements. The other is equipped with a high powered optical microscope with a working distance greater than 1 cm. This facilitates probing of submicron structures. | ||
| Signatone Probe Station | ||
Sample Packaging
K&S Wire Bonders
| Aluminum (Al) wedge and Gold (Au) ball bonders are available to assist in sample packaging. |
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| K&S Wire Bonders |
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