Trion Technology is represented by
Crystec Technology Trading GmbH
Company Overview Plasma Plasma Etcher Asher Failure Analysis PECVD Si3N4 Si02 Endpoint
| Failure analysis of integrated circuits by dry or plasma etching (RIE reactive ion etching), delayering. | ||
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Trion Technology is represented by
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English
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francais Company Overview Plasma Plasma Etcher Asher Failure Analysis PECVD Si3N4 Si02 Endpoint |
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For failure analysis of intergrated circuits (ICs) it is necessary to open and delayer a
chip layer by layer in order to find a hidden defect or defects. It is necessary to determine the cause of failure
to prevent future occurrence, and/or to improve the performance of the device. Increased circuit densities, smaller
feature sizes and ever increasing multilayer technologies have created many challenges for failure analysis
engineers. Today Trion Phantom plasma etchers are used for this job.
Trion engineers have a lot of experience with failure analysis and all equipment necessary to develop and
demonstrate those tools (e.g. a raster electron microscope).
Depending on the desired information, delayering of the integrated circuit IC is usually performed by either of
two strategies, anisotropic removal of all dielectric layers, or sequential removal of all layers including
conductors.
In this procedure, all dielectric layers are removed anisotropically down to the silicon surface. Metal conductors will be left sitting on top of pedestals of dielectric material. An anisotropic etch must be used to prevent undercut of the metal lines, or else the stress in the metal will usually cause delamination. When the silicon dioxide etch approaches the polysilicon gate material, a CF4 + CHF3 gas mix is used to improve selectivity to silicon and decrease erosion of the polysilicon lines.
Anisotropic dielectric removal is useful, but in many situations defects or other
features of interest may lie underneath conductors. In this case, it is necessary to remove metal and dielectric layers
sequentially. Proper etch recipe selection is crucial to prevent inadvertent removal of layers not intended to
be etched. It is important that lower level metals layers are not exposed when the top level metal is etched,
or the lower level metals will be removed prematurely.
In order to maintain planarity during sequential delayering of an IC, it is desirable to stop each dielectric
etch when a level is reached that is even with the next metal layer to be etched.
Thus when the passivation is etched, it should be etched level with the base of the metal line.
Since there is no etch stop between the dielectric layers, this process requires a timed etch.
Inductively coupled plasma systems offer many advantages of straight RIE systems such as faster etch rates, cleaner and more selective etches, but also produce much lower plasma damage due to the lower operating voltages or DC bias on the sample surface. These benefits are also important to the failure analysis engineer. The higher etch rate allows the FA engineer to run a lower RIE power, which is still needed to form a plasma potential at the sample and obtain an anisotropic etch. This way, low device damage is created. RIE etching alone only accomplishes good etching down to three-level metal while with the ICP 4-6 level metal devices can be etched (see picture).
A more detailed description of the usage of plasma etchers for failure analysis is available at the Trion paper A. Crockett, M. Almoustafa, W. Vanderlinde "Plasma Delayering of Integrated Circuits".
Crystec Technology Trading GmbH, Germany, www.crystec.com, +49 8671 882173, FAX 882177
A standard version (very left) and a ICP-version (left) are
available. Also available is the standard version with a vacuum
loadlock (right) and the ICP-version with a vacuum loadlock (very right)
The Phantom III RIE is designed for etching nitrides, oxides and any
films or substrates requiring fluorine-based chemistries. It’s modular
design, mounted on a space-saving platform, is the system of choice for
many users throughout the world.
For IC failure analysis, usually the Phantom plasma etcher with ICP is used in order to achieve high etch rates and low damage. Load lock is normally not used in failure analysis in order to keep the loading and unloading time of samples as short as possible. Just in some cases, when special gases are used, it is necessary to use a load lock for safety reasons.
Reactor - The cathode and anode are both machined out of single blocks of aluminum. After critical inspection they are hard anodized for protection from process chemistries. The bottom electrode is available in either 200mm or 300mm sizes and can process parts and wafers up to 200mm or 300mm in diameter. Process gases are introduced into the chamber either by an annular ring or showerhead manifold.
Automatic Matching Network - The uniquely designed network is built in as an integral part of the bottom electrode assembly to ensure accurate tuning, low transmission loss and virtually no RF radiation outside the network itself. The network uses a phase magnitude sensor and amplifiers to provide instantaneous feedback for quick precise tuning.
RF Generator - The Phantom III comes with a 600 watt, 13.56 MHz, solid state RF generator. (The Phantom LT comes with a 300 watt RFgenerator).
Touch Screen Operator Interface - A color flat panel display with touch screen interface provides the operator with full process information at all times. The software interface guides the operator through each sequence in a logical fashion and gives fingertip control of all process parameters.
PC Process Controller - The PC process controller provides simple and reliable system control. The graphical software package creates programs in block diagram form. Process recipes are stored on the hard drive or can be stored on USB flash drives allowing each operator to maintain individual recipes.
AC Distribution Module - The AC distribution module automatically distributes predefined power quantities to the various internal components. When the Emergency Power Off button is tripped, the RF power is shut off and all valves involved with gas delivery are automatically closed and the machine automatically powers down to a safe standby mode. This system includes separate power controls for the main AC and peripherals.
Automatic Pressure Control - Every Trion system includes a butterfly pressure control valve operated directly by the process controller. This provides independent pressure control separate from all other processing parameters.
Gas Delivery System - State-of-the-art technology is utilized to ensure the utmost integrity and purity. Each Phantom III reaction chamber accommodates up to eight mass flow controllers and all plumbing utilizes surface mount, C-seal technology or orbital welded VCR fittings. (The Phantom LT comes with two mass flow controllers).
Safety - The system meets all SEMI S2-93 safety requirements. A third party safety review is available upon request.
Facilities - Facility schematics can be provided upon request.
Pumping Systems - Each reaction chamber requires it’s own pump. Trion can supply these as needed according to your requirements. There are mechanical, dry and turbo pump options available. You may choose to provide your own pump(s) or they can be purchased directly from Trion. All pump options provided by Trion are proven systems chosen to best meet your specific process needs.
Temperature Control - An external chiller or heater/chiller recirculator may be recommended. By controlling the reactor temperature (bottom electrode), process reproducibility is greatly enhanced and the etch byproducts are more readily volatilized.
Endpoint Detection Systems - Trion offers both optical and laser endpoint detection options which allows the user to measure film thickness changes in-situ during the etch process. These systems are integrated into and controlled by Trion software.
Inductively Coupled Plasma - Trion’s carefully engineered ICP is a proven option for failure analysis. It dramatically reduces radiation damage and contamination from RIE sputtering and greatly increases selectivity to other films. It allows for higher plasma densities as power is transferred into the bulk plasma via the magnetic field resultant from inductive coupling. This enables processing at lower pressure, which has a number of significant benefits. It allows for tight anisotropy in high aspect ratio structures and reduces microloading effect. Trion’s ICP source will result in improved etch rates, profile control, uniformity and selectivity with a dramatic reduction in RIE radiation damage. The Phantom III ICP comes with a 600 or 1250 watt, 13.56 MHz power supply and a built-in automatic matching network. (The Phantom LT ICP comes with a 600 watt power supply.)
Electrostatic Chuck - Maintaining cooler substrate temperatures during etching is often critical. Trion’s electrostatic chuck holds the wafer securely to the chuck by electrostatic forces while flowing a small quantity of helium onto the backside of the wafer, providing significant cooling.
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