Atomic Layer deposition of copper films
OHSU # 0565
This invention relates to a method of depositing an ultra-thin seed layer of copper film on a silicon substrate using Atomic Layer Deposition (ALD). This method uses a carrier gas to deposit a source metal in the presence of a reducing agent so that the rate, temperature and number of phases can be easily controlled. This process may be used for the deposition of conformal seed layers for subsequent electrodeposition of thicker films for microelectronic interconnect applications in state of the art electronic devices.
This process can also be reversed to remove a film from a surface, one atomic layer at a time, providing a precise way of etching a metallic film. This would include applications requiring etching of copper films deposited on low-k dielectrics, which tend to be very soft materials.
Chemical vapor deposition (CVD) and Physical Vapor Deposition have been used to deposit metallic substances on substrates. Of these, electroplating or electrodeposition has become the method of choice for the microelectronics industry. With the advent of nanotechnology, there is an increasing need to develop methods for depositing nanoscale metallic films on substrates for use in producing items such as circuit boards and architectural coatings in MEMs, NEMs, and medical instruments and implants.
The copper film produced with this ALD method is highly conformal to the architecture of the substrate surface and can be easily controlled at the atomic level, reducing the rough texture large amounts of impurities associated with deposition methods.
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