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PVD CuMn self-forming barrier (SFB) approach was investigated on 300mm wafers as an alternative to conventional PVD Ta/Cu metallization. Cu fill on very aggressive dual damascene features targeted for beyond 32nm node was evaluated along with integrated electrical and reliability performance on low-k (k=2.6) interlayer dielectric (ILD).

Planar capacitors can quickly test material properties of metals and dielectrics for interconnects. A sidewall capacitor device is used to evaluate metal thin-film barriers. Etch stop planar capacitors in turn can test multi-layer etch stops, exposing differences between leaky and good etch stop films. Fillable planar capacitors are also fabricated and results presented for that class of fill materials.

A monolithic CMOS compatible process has been developed to realize vertically integrated devices in silicon. The method involves the implantation of an oxygen into a patterned silicon substrate to form buried guiding structures. These buried devices are separated from a surface silicon layer by an intervening layer of silicon dioxide formed through the implantation process. Photolithography and etching is used to define devices on the surface silicon layer. The method has been utilized to realize the vertically coupled microdisk resonators and a variety of microresonator-based integrated optical elements. A new method for extraction of the unloaded Q of a cavity from its measured spectrum is also described.

A sidewall planar capacitor (SW CAP) vehicle is developed to closely simulate processing conditions for metal barrier and dielectric in an integrated structure. For a known tantalum barrier for copper on a low-K dielectric, SW CAP TDDB is similar to those measured on an integrated vehicle. SW CAP results are useful for comparing electrical reliability of different dielectric systems, and effective in determining physical continuity of copper metal barriers.

Earlier [1, 2] work highlighted an integrated process for electrically functional 12 nm half-pitch copper interconnects in an ultralow-k interlayer dielectric (ILD). In this paper, we focus on understanding and reducing undesired effects such as pattern asymmetry/distortion, and line undulation/ collapse. Key defect modes and possible solution paths are discussed. Line undulation can occur when the ILD feature changes shape under the stress of the sacrificial hard mask(s) (HM) during patterning, resulting in “wavy” instead of straight features. The amount of undulation is directly related to mechanical properties such as elastic modulus, residual stresses of patterned HMs and the ILD, as well as the dimensions and aspect ratio of the features. Line collapse is observed post wet-clean processing when one or more of the following is true - Insufficient ILD mechanical strength, excessive pattern aspect ratio, or non-uniform drying. Pattern asymmetry , or unequal critical dimensions (CD) of trenches defined by the same backbone, is a typical problem encountered during spacer-based pitch division. In pitch quartering (P/4), three different trench widths result from small variations in backbone lithography, spacer CD and etch bias. Symmetric patterning can be achieved through rigorous control of patterning processes like backbone definition, spacer deposition and downstream etches. Plasma-based ash and energetic metal deposition were also observed to degrade patterning fidelity of ultra low-k film, and also need to be closely managed.

A process to achieve 12 nm half-pitch interconnect structures in ultralow-k interlayer dielectric (ILD) is realized using standard 193 nm lithography. An optimized pattern transfer that minimizes unwanted distortion of ILD features is followed by copper fill. Electrical measurements that validate functionality of the drawn structures are presented.

A modified separation by implantation of oxygen process has been developed to sculpt vertically coupled microdisk resonators in silicon. The approach involves the implantation of oxygen ions into a silicon substrate, patterned with thermal oxide, to define waveguides on the bottom silicon layer, and photolithography and reactive ion etching to define the microdisk resonators on the top silicon layer. The top and the bottom silicon layers are separated by the oxide layer that was formed after the oxygen implantation. Fabricated microdisk resonators show resonances with a Q value of 10 300 and a free spectral range of 5.4nm.

The patterning of a 34 nm metal pitch interconnect was realized using a spacer-based pitch quartering scheme. The pattern is transferred into an ultralow-k ILD using a process that avoids ILD buckling and structure collapse. Resulting features were metallized with copper, and electrically characterized. Measurement results show expected trends with drawn dimensions.

The ruthenium (Ru) liner based metallization scheme depends on the ability to electrodeposit Cu onto thin, resistive Ru substrates with substantially high Cu nuclei density. In the present paper, a novel electrochemical bath that utilizes Cu-complexing agents to improve the nucleation of plated Cu films on Ru is presented. Such chemistries can generate Cu nucleation density on Ru greater than 1012 nuclei/cm2, thereby enabling robust gap-fill in aggressive (CD∼30nm) dual damascene structures. Complexed-Cu plating chemistries thus provide great potential for extending Cu metallization to future technology nodes.

A novel approach to three-dimensionally (3-D) integrate nanophotonic and electronic devices in silicon is described. The method is based on the SIMOX (Separation by Implantation of OXygen) process, to realize three-dimensionally (3-D) integrated devices in a monolithic fashion. In this approach, photonic and electronic devices are realized on vertically stacked layers of silicon, separated from each other by a dielectric layer of silicon dioxide formed through the process of oxygen implantation. Opto-electronic integration is demonstrated by realizing photonic circuits in a subterranean silicon layer and Metal-Oxide-Semiconductor (MOS) transistors on a surface layer of silicon. Optical and electronic functionalities are thus separated into two different layers of silicon, paving the way towards dense three-dimensional opto-electronic integration. This has the significant advantage that photonic devices do not consume any of the expensive silicon real estate required for CMOS circuitry. The versatility of the technique of SIMOX 3-D sculpting in obtaining complex optical circuitry is also demonstrated by synthesizing a cascaded microdisk structure that may be utilized to tailor the passband characteristics of optical filters.

The integration of photonics and electronics on a single silicon substrate requires technologies that can add optical functionalities without significantly sacrificing valuable wafer area. To this end, we have developed an innovative fabrication process, called SIMOX 3-D Sculpting, that enables monolithic optoelectronic integration in a manner that does not compromise the economics of CMOS manufacturing. In this technique, photonic devices are realized in subsurface silicon layers that are separated from the surface silicon layer by an intervening SiO2 layer. The surface silicon layer may then be utilized for electronic circuitry. SIMOX 3-D sculpting involves (1) the implantation of oxygen ions into a patterned silicon substrate followed by (2) high temperature anneal to create buried waveguide-based photonic devices. This process has produced subterranean microresonators with unloaded quality factors of 8000 and extinction ratios >20dB. On the surface silicon layers, MOS transistor structures have been fabricated. The small cross-sectional area of the waveguides lends itself to the realization of nonlinear optical devices. We have previously demonstrated spectral broadening and continuum generation in silicon waveguides utilizing Kerr optical nonlinearity. This may be combined with microresonator filters for on-chip supercontiuum generation and spectral carving. The monolithic integration of CMOS circuits and optical modulators with such multi-wavelength sources represent an exciting avenue for silicon photonics.

Three-dimensional optoelectronic integration can be achieved in SOI wafers using the process of SIMOX 3D sculpting. Micro-resonators, with unloaded Q of 8000 and extinction ratio >20 dB, were fabricated in a buried silicon layer and MOS transistor structures were fabricated on the surface silicon layer using a patterned SIMOX process.

Three-dimensionally integrated microdisk resonators have been employed to realize Vernier filters in Silicon. Cascaded configuration of vertically-coupled microdisk resonators with dissimilar radii increases the free spectral range of filters from 5.5 nm to 23 nm.

Monolithic integration of photonics and electronics has been achieved in silicon by vertically integrating metal-oxide-semiconductor field-effect transistors and waveguide-coupled microdisk resonators in a double-layer silicon-on-insulator wafer, thus paving the way towards dense three-dimensional optoelectronic integration.

Although the Raman effect is nearly two orders of magnitude stronger than the electronic Kerr nonlinearity in silicon, under pulsed operation regime where the pulse width is shorter than the phonon response time, Raman effect is suppressed and Kerr nonlinearity dominates. Continuum generation, made possible by the non-resonant Kerr nonlinearity, offers a technologically and economically appealing path to WDM communication at the inter-chip or intra-chip levels. We have studied this phenomenon experimentally and theoretically. Experimentally, a 2 fold spectral broadening is obtained by launching ~4ps optical pulses with 2.2GW/cm2 peak power into a conventional silicon waveguide. Theoretical calculations, that include the effect of two-photon-absorption, free carrier absorption and refractive index change indicate that up to >30 times spectral broadening is achievable in an optimized device. The broadening is due to self phase modulation and saturates due to two photon absorption. Additionally, we find that free carrier dynamics also contributes to the spectral broadening and cause the overall spectrum to be asymmetric with respect to the pump wavelength.

A new process has been developed to create vertically-integrated photonic and optoelectronic circuits in silicon. The approach is the 3-D extension of the SIMOX process where buried SiO2 sections can be selectively created by using oxygen implantation, through a mask, followed by annealing. By controlling the implant energy, dose, mask area and thickness, arbitrary 3-D arrangements of Silicon/SiO2 can be created. The process has been used to create vertically coupled microdisk resonators and add-drop wavelength multiplexers on a silicon wafer.

This paper presents the design and operation of Si and GeSi Raman lasers and amplifiers. Different laser applications in various practical fields are also discussed.

Nonlinear optical devices, with silicon-on-insulator material system as platform for their fabrication are discussed. Third order nonlinearity in silicon offers active functionalities in silicon by taking advantage of the high index contrast and tight beam confinement. Among the third order effects; Raman, Kerr nonlinearity, two-photon absorption are particularly strong

This paper reports the fabrication and characterization of add-drop filters based on vertically coupled microdisk resonators in silicon. SIMOX 3-D sculpting is the technique used to fabricate monolithically integrated filters based on microdisk resonator structures that show adjacent channel cross talk suppression as high as 15 dB for channels that are separated by 1.5 nm.

In this paper we report the demonstration of vertically coupled microdisk resonator structures on SOI substrates, using the technique of SIMOX 3-D sculpting.

In this paper, fabrication of three dimensionally integrated nano-optical structures in silicon-on-insulator (SOI) substrates using the process of separation by implantation of oxygen (SIMOX) is reported. Buried rib waveguides with lowest ever loss with the SIMOX process, reported with the fabrication of vertically integrated structures using conventional lithography and etching process, demonstrate the capability to sculpt 3-D integrated optical devices.

Vertically coupled microdisk resonator structures have been synthesized on Silicon utilizing a modified Separation by Implantation of Oxygen (SIMOX) technique. Resonances are observed with Q values of 6300 and free spectral range of 5.4 nm.

Monolithic integration of photonics and electronics has been achieved in silicon by three-dimensionally integrating metal-oxide-semiconductor field-effect transistors and waveguide-coupled microdisk resonators. Implantation of oxygen ions into a silicon-on-insulator substrate with a patterned thermal oxide mask followed by a high temperature anneal was utilized to realize the buried photonic structures. This results in the formation of vertically stacked silicon layers separated from each other by an intervening oxide layer. Transistors are fabricated on the surface silicon by conventional processing techniques. Optical and electronic functionalities are thus separated into two different layers of silicon, paving the way toward dense three-dimensional optoelectronic integration.

Laterally-coupled silicon microresonators are fabricated beneath the surface of a silicon-on-insulator substrate using a modified separation by implantation of an oxygen technique. Implantation of oxygen ions into a substrate with patterned thermal oxide mask was utilized to realize buried waveguiding structures. Microdisk resonators in the buried silicon layer show loaded quality factors of 2000, with extinction ratios in excess of 20dB. The process also results in the formation of a silicon layer on the surface of the wafer that is suitable for the fabrication of electronic devices, thereby paving the way for three-dimensional monolithic integration of electronics and photonics in silicon.

Add-drop filters, based on vertically coupled microdisk resonators, have been realized in silicon, using a modified separation by implantation of oxygen process. Buried rib waveguides in the bottom-layer silicon, of a two-layer structure, are coupled to microdisk resonators in the top-layer silicon through a silicon dioxide layer formed by oxygen implantation. The radii of the microdisk structures were varied suitably to obtain resonators with slightly shifted resonance wavelengths. The average adjacent channel crosstalk suppression of these filters exhibits an upper limit of 12.11dB and a lower limit of 6.2dB over the wavelength band under consideration.

The prospect for generating supercontinuum pulses on a silicon chip is studied. Using ~4ps optical pulses with 2.2GW/cm(2) peak power, a 2 fold spectral broadening is obtained. Theoretical calculations, that include the effect of two-photon-absorption, indicate up to 5 times spectral broadening is achievable at 10x higher peak powers. Representing a nonlinear loss mechanism at high intensities, TPA limits the maximum optical bandwidth that can be generated.