Abstract:
A dispersion mitigating interleaver assembly has a first unbalanced Mach-Zehnder interferometer (MZI) assembly which includes first and second output ports and which has first transmission vs. wavelength curve and a first dispersion vs. wavelength curve. The dispersion mitigating interleaver assembly also includes a second unbalanced MZI assembly which has a second transmission vs. wavelength curve and a second dispersion vs. wavelength curve. The second unbalanced MZI assembly receives an output from one of the first and second output ports of the first unbalanced MZI assembly. The second transmission vs. wavelength curve is substantially the same as the first transmission vs. wavelength curve and the second dispersion vs. wavelength curve is substantially opposite with respect to the first dispersion vs. wavelength curve, such that dispersion is substantially cancelled by the cooperation of the first and second unbalanced MZI assemblies.
Abstract:
Fabrication of improved low-k dielectric structures is disclosed. Low-k dielectric structures are fabricated while overcoming the otherwise existing problems associated with the use of low-k dielectric materials. In one embodiment, the physical properties of a low-k dielectric material is modified by exposing the low-k dielectric material to electron beams. The exposed portion of the low-k dielectric material becomes easier to etch and clean and exhibits greater mechanical strength and a reduction in absorption of moisture. In another embodiment, a number of incremental exposure and etch steps are performed to fabricate a desired structure. In yet another embodiment, the steps of exposure of a low-k dielectric material are combined with the etch steps. The exposure and the etching of the low-k dielectric material are performed concurrently in the same system. In still another embodiment, a single exposure and a single etch step are utilized to fabricate a desired structure. All the disclosed embodiments can be practiced by exposing the low-k dielectric material to ion beams instead of electron beams.
Abstract:
A via is first etched in a dielectric. Then a conformal layer is deposited over the dielectric and the via to reduce an initial width of the via to a target width. A trench is then etched in the dielectric and the conformal layer. Since the width of the via is reduced from the initial width to the target width, the resulting final via has a high aspect ratio. The via and the trench are then filled with metal which contacts an interconnect metal situated below the via. In one embodiment, copper is used to fill the via and the trench and also as the interconnect metal below the via. In one embodiment, the dielectric is silicon dioxide or fluorinated silicon dioxide and the conformal layer is silicon dioxide. In another embodiment, the dielectric is silicon dioxide or fluorinated silicon dioxide while the conformal layer is silicon nitride. To etch the trench in the dielectric and the conformal layer, a timed exposure to a carbon fluoride based plasma is employed. Alternatively, instead of timing the exposure to plasma, a suitable etch stop layer is used. In the embodiment where a conformal layer of high dielectric constant is used, the conformal layer remaining on the dielectric surface is removed using either chemical mechanical polishing or by plasma etching. The final structure is a via and a trench where the via's side walls are covered by the conformal layer while the trench's side walls are not covered by the conformal layer.
Abstract:
A technique for fabricating a dual damascene interconnect structure using a low dielectric constant material as a dielectric layer or layers. A low dielectric constant (low-.di-elect cons.) dielectric material is used to form an inter-level dielectric (ILD) layer between metallization layers and in which via and trench openings are formed in the low-.di-elect cons. ILD. The dual damascene technique allows for both the via and trench openings to be filled at the same time.
Abstract:
A method or utilizing electroless copper deposition to selectively form encapsulated copper plugs to connect conductive regions on a semiconductor. A via opening in an inter-level dielectric (ILD) provides a path for connecting two conductive regions separated by the ILD. Once the underlying metal layer is exposed by the via opening, a SiN or SiON dielectric encapsulation layer is formed along the sidewalls of the via. Then, a contact displacement technique is used to form a thin activation layer of copper on a barrier metal, such as TiN, which is present as a covering layer on the underlying metal layer. After the contact displacement of copper on the barrier layer at the bottom of the via, an electroless copper deposition technique is then used to auto-catalytically deposit copper in the via. The electroless copper deposition continues until the via is almost filled, but leaving sufficient room at the top in order to form an upper encapsulation layer. The SiN or SiON sidewalls, the bottom barrier layer and the cap barrier layer function to fully encapsulate the copper plug in the via. The plug is then annealed.
Abstract:
A technique for utilizing an electric field to initiate electroless deposition of a material to form layers and/or structures on a semiconductor wafer. The wafer is disposed between a positive electrode and a negative electrode and disposed so that its deposition surface faces the positive electrode. A conductive surface on the wafer is then subjected to an electroless copper deposition solution. When copper is the conductive material being deposited, positive copper ions in the solution are repelled by the positive electrode and attracted by the negatively charged wafer surface. Once physical contact is made, the copper ions dissipate their charges by accepting electrons from the conductive surface, thereby forming copper atoms on the surface. The deposited copper have the catalytic properties so that when a reductant in the solution is absorbed at the copper sites and then oxidized, additional electrons are released into the conductive surface. The formation of the initial layer of copper functions as a seed layer for further electroless growth of copper. The same electroless deposition solution can be used for both the initial activation layer and the additional autocatalytic growth on to the seed layer.