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ALD Products - Applications
APPLICATIONS MATERIALS SYSTEMS
Gate Stacks
A gate is an element of a transistor to which voltage may be applied in order to turn a circuit on or off. A gate structure requires the use of insulating materials to allow the buildup of an electrical field.
For gate dielectric applications, traditional insulating materials such as silicon dioxide and silicon nitride can no longer meet the challenge of advanced ULSI device performance. (ULSI, ultra large-scale integration, refers to integrated circuits (ICs) containing greater than 100,000 transistors.) Some promising new gate dielectric materials that can be produced using ALD include, among others, zirconium oxide and hafnium oxide and their silicates.
The key requirement for the gate application is the stability of these materials when they are in contact with single crystal silicon substrates and with poly-silicon gate electrodes. Low leakage current is also required, although this is more critical in logic applications than it is for DRAM. Another critical requirement for building gate stacks is accurate control of the thickness of the gate dielectric films.
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Capacitors
A capacitor is a circuit element formed by placing an insulating layer between two conducting layers; its function is to store a measure of electrical charge until needed.
The industry trend of increasing memory density dictates a trend of increased capacitance density. Memory chip manufacturers continue to strive for reducing the size of capacitors while ensuring that capacitors and nearby transistors are adequately isolated form each other. Substantial increased density can be achieved by increasing both the area of the capacitor and the dielectric constant (high-k), as well as decreasing the thickness of the insulating film in the capacitor.
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C = DRAM
Memory capacitor
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As technology progresses, the area on the chip that is available for each capacitor shrinks. In order to maintain a large capacitor area, 3-D structures are enhanced, resulting in some very high-aspect ratio features. In these aggressive structures, metal and dielectric films must be uniform and pinhole-free. In addition, low leakage of the electrical current is very critical for this application.
Genus' ALD technology provides control of ultra thin films one atomic layer at a time and offers superior leakage current performance. It also provides amazing, 100% step coverage for the high-aspect ratio features.
Interconnects
Interconnects are the "wiring" that connect all of the various functional circuit components within integrated circuits (ICs). Interconnects consist of barrier films, and films such as aluminum or copper deposited on top of the barrier films become the "bulk" interconnect film that carries electrons.
For high density, high performance devices such as state-of-the-art microprocessors, interconnect technology can be a dominant factor in final device performance, and can determine the competitiveness of the device (product) in the market.
It has been widely recognized by the industry that ALD films will play a vital role for interconnect barrier applications. As device geometries scale, barrier films are becoming very thin, but still require perfect uniformity and step coverage. These are the challenges confronting current PVD and CVD deposition technologies, which will be addressed and resolved in the coming years by ALD deposition techniques. ALD interconnect applications are expected to emerge several years later than capacitor and gate applications.
Non-Semiconductor Applications
A large variety of technologies and products in non-semiconductor market segments can benefit from the superior properties of ALD films. One popular and flexible material that can be used for various applications is aluminum oxide, which Genus has developed into mature technology. The immediate application includes the gap dielectrics of magnetic recording heads, MEMS (MicroElectroMechanical Systems) fabrication, organic light emitting displays (OLED) and ink jet applications.
Genus is currently providing ALD technology for advanced sensor element "gap" applications. A gap is a tiny feature of electromagnetic recording heads. Recording heads are miniature (about 1mm2) components that function to read and write information to and from a hard-drive disk or another storage medium.
Building the gap structure requires
extremely dense, pinhole-free and uniform films. The low temperature
deposition technology available from Genus is a direct and qualified
replacement for established sputtering based processes, which are
unable to satisfy future requirements. See our Markets section for further discussion of non-semiconductor applications.
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