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This paper reports a novel launch scheme for coupling light into the skew rays of a graded index fiber. This is accomplished by utilizing a diffractive optical element in conjunction with a single mode fiber to mode match a graded index fiber. Results are used to confirm the fact that the element does improve the coupling into the skew rays of graded index fiber. This approach offers an alternative to existing methods based on tilting and angular offsets for the conditioned launch problem.

We present a method for optimizing a free-form illuminator implemented using a diffractive optical element (DOE). The method, which co-optimizes the source and mask taking entire images of circuit clips into account, improves the common process-window and 2-D image fidelity. We compare process-windows for optimized standard and free-form DOE illuminations for arrays and random placements of contact holes at the 45 nm and 32 nm nodes. Source-mask cooptimization leads to a better-performing source compared to source-only optimization. We quantify the effect of typical DOE manufacturing defects on lithography performance in terms of NILS and common process-window.

We present advancements in the manufacture of high-performance diffractive optical elements (DOEs) used in stepper/scanner off-axis illumination systems. These advancements have been made by employing high resolution lithographic techniques, in combination with precision glass-etching capabilities. Enhanced performance of DOE designs is demonstrated, including higher efficiency with improved uniformity for multi-pole illumination at the pupil plane, while maintaining low on-axis intensity. Theoretical predictions of the performance for several classes of DOE designs will be presented and compared with experimental results. This new process capability results in improved performance of current DOE designs, and enables greater customization including control of the output spatial intensity distribution for future designs. These advancements will facilitate continuous improvements in off-axis illumination optimization required by the end user to obtain larger effective lithographic process windows.

As CDs continue to shrink, lithographers are moving towards using off-axis illumination while continuing to decrease the operating wavelength to improve their CD budget. Currently DUV lithography at 248nm and 193nm are driving the ability of the foundries and IDM’s to meet or exceed the SIA roadmap for semiconductor chip performance. In time, however, the industry will migrate to the even shorter wavelengths of 157nm and 13nm. To meet today’s needs with 248nm and 193nm requires the use of Resolution Enhancement Techniques such as Optical Proximity Correction, Phase Shift Mask, and Off Axis Illumination. The need for these techniques will be only slightly reduced as the industry migrates to 157nm in several years. Off-axis illumination (the topic of this paper) has been shown to significantly increase the lithographic process window and there have been several papers over the last few years describing various illumination profiles designed for application specific optimization. These include various annular and quadrupole illumination schemes including weak quadrupole, CQUEST, and Quasar Diffractive optics, if incorporated into the design of the illumination system, can be used to create arbitrary illumination profiles without the associated light loss, thus maintaining throughput while optimizing system performance. We report on the design and fabrication of such devices for use with KrF, ArF, and F 2 scanners.

A key barrier to market penetration of optics into the electronic marketplace for a wide range of applications is cost. One of the advantages of computer generated holograms is the low fabrication cost based on VLSI processing technology. In addition, as further investment is made and the technology advances, CGH fabrication technology will follow that investment/learning curve to achieve further cost reduction. In this presentation, the design of a new low cost computer generated hologram for coupling a laser diode to single mode fiber will be presented. >

The Polymer Optical interconnect Technology (POINT) is a collaborative program among GE, Honeywell, AMP, AlliedSignal, Columbia University and University of California at San Diego (UCSD), sponsored by ARPA, in developing affordable optoelectronic packaging and interconnect technologies for board- and backplane-level optical interconnect applications. The POINT program leverages on the existing electronic design, processing, fabrication and MCM packaging technologies to optoelectronic packaging. The POINT program also incorporates several state-of-the-art optoelectronic technologies that include: high speed VCSEL for multi-channel data transmission; flexible optical polymer waveguides and low-loss polymers for board and backplane interconnects; low-cost diffractive optical elements (DOE) for board-to-backplane interconnect; and use of molded MT-type connectors to reduce weight and size. In addition, to further reduce design and fabrication cycle times, CAD tools for multimode optical waveguide modelling, and for mechanical modelling of optoelectronic packaging will be employed to aid the technology development.

We developed a statistical model of the passive alignment process. This model allows us to calculate the distribution of VCSEL to waveguide alignment tolerances for laser micromachining of the waveguide and pedestal alignment features. Using this distribution as input for the optical model, the distribution of optical coupling efficiencies for the packaging tolerances was calculated. The coupling efficiencies for the passively aligned waveguides to the VCSEL array sources were measured and compared to the simulation results.

The technical approach and progress achieved under the Polymer Optical Interconnect Technology (POINT) program are described in this paper. The POINT program is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University, and University of California at San Diego (UCSD), sponsored by DARPA/ETO, to develop affordable optoelectronic packaging and interconnect technologies for board and backplane applications. Specifically, progress is reported on (a) development of batch-operated plastic VCSEL array packaging technology using planar fabrication, (b) demonstration of high-density optical interconnects for board and backplane applications using polymer waveguides to a length of 50 cm at an I/O density of 250 channels per inch, (c) development of low-loss optical polymer waveguides with loss less than 0.1 dB/cm at 850 nm, and (d) development of passive alignment processes for efficient coupling between a VCSEL array and polymer waveguides. Significant progress has also been made under the POINT program at Columbia University, in applying CAD tools to simulate multimode-guided wave systems and, at UCSD, to assist mechanical and thermal design in optoelectronic packaging.

Due to the explosive growth in high speed network communication and the rapid advance in the processor speed and processing power, data transfer bandwidths between chips, modules, board, backplane and cabinets have increased drastically. The required interconnect bandwidths for efficient data communication across different platforms have increased accordingly. The optical backplane offers a much higher data bandwidth and interconnect density with minimum cross-talk. However, in order to successfully deploy optical interconnect in complex electronic systems such as board and backplane and offer performance/cost comparable of superior to electronic solutions, the development of optoelectronic interconnect devices, components, packaging and processing technologies must be compatible with the existing electronic interconnect counterparts. In this work, we report the recent development of high density optical interconnect technology using VCSEL and polymer waveguides for board and backplane level applications.

This paper describes the technical approach and progresses of the POINT (Polymer Optical Interconnect Technology) program. This project is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University and University of California at San Diego (UCSD), sponsored by DARPA/ETO to develop affordable optoelectronic packaging and interconnect technologies for board and backplane applications. In this paper, we describe the recent development under this program in the following areas: (a) a high density optical interconnect for board and backplane applications using polymer waveguides (Polyguide) to demonstrate high I/O density (100 /spl mu/m channel spacing) and high speed (/spl sim/1 Gbps) interconnect with an interconnect distance to 280 mm, (b) a high density and high speed VCSEL array packaging technology that employs planar and batch fabrication processes scaleable to large volume, low-cost manufacturing, (c) passive alignment techniques for reducing the recurrent cost in an optoelectronic assembly, (d) low-loss optical polymers for board and backplane level interconnects, and (e) CAD tools for modeling multimode guided wave systems and assisting optoelectronic packaging mechanical design.

As CDs continue to shrink, lithographers are moving more towards using off-axis illumination schemes to increase their CD budget. There have been several papers over the last few years describing various custom illumination profiles designed for application specific optimization. These include various annular and quadrupole illumination schemes including weak quadrupole, CQUEST, and QuasarTM. Diffractive optics, if incorporated into the design of the illumination system, can be used to create arbitrary illumination profiles without the associated light loss, thus maintaining throughput while optimizing system performance. Diffractive optical elements used to generate efficient illumination profiles for 248 nm and 193 nm excimer laser-source scanners, have been reported and realized in fused silica. The fabrication of such elements in calcium fluoride (CaF2), for use in 157 nm wavelength lithographic projection tools has been developed and is presented in this paper. Three different categories of elements are shown: large-diagonal-cluster diffusers, medium- and small-rectangular-cluster diffusers. The diffusers were fabricated as binary phase devices, in order to determine calcium fluoride processing capabilities.

Graded index fiber has a limited bandwidth due to defects introduced in the fiber manufacturing process. In this paper, an alternative launch technique is presented using a diffractive element to excite specific modes in a fiber to maximize the bandwidth of graded index fiber.

An alternative method is presented for launching light into graded index fiber. This approach utilizes a diffractive element to match the phase of the launched light into specific modes of the graded index fiber.

Standard laser welding practices are limited by the intensity profile of the beam and spot size. The introduction of Diffractive Optical Elements (DOE) to the welding process allows for new beam shapes that are better suited to the welding process. A particular problem in laser welding is the joining of dissimilar materials. Because these materials have different material properties including different melting temperatures, it is difficult to synchronize the welding process using a single spot. Additionally, significant thermal stresses are introduced by the welding process because of the keyhole weld shape formed by a gaussian beam. By using a power splitting DOE, two spots of unequal intensity distributions may be projected onto each side of the weld joint. This paper discusses the use of DOEs in laser welding and joining of dissimilar materials. Results are presented from the testing of several candidate aerospace materials.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Silicon v-groove structures have been utilized for passive positioning of optical fiber for fiber optic and opto- electronic applications. In this paper, we will present our results of using micro-machined silicon v-groove arrays to passively align optical fiber arrays to micro rod optics. We will also demonstrate the integration of N fiber arrays bonded into the silicon v-groove with a 1xN micro lens array, which is composed of a 2 inch-phase level diffractive optics. For the assembly of 1x6 fiber array and lens array with 16 phase level diffractive optics, the experimental results indicated that total insertion loss per link is typically 1.5-2.0 dB/channel.

The technical approach and progress achieved under the Polymer Optical Interconnect Technology (POINT) program are described in this paper. The POINT program is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University, and University of California at San Diego (UCSD), sponsored by DARPA/ETO, to develop affordable optoelectronic packaging and interconnect technologies for board and backplane applications. Specifically, progress is reported on (a) development of a plastic VCSEL array packaging technology using batch and planar fabrication, (b) demonstration of high-density optical interconnects for board and backplane applications using polymer waveguides to a length of 50 cm at an I/O density of 250 channels per inch, (c) development of low-loss optical polymer waveguides with loss less than 0.1 dB/cm at 850 nm, and (d) development of passively alignment processes for efficient coupling between a VCSEL array and polymer waveguides. Significant progress has also been made under the POINT program at Columbia University, in applying CAD tools to simulate multi-mode-guided wave systems and, at UCSD, to assist mechanical and thermal design in optoelectronic packaging. Because of space limitations, these results will be described elsewhere in future publications.

Optical connectors utilize microlens elements for coupling light into and out of fibers. Typically, these lenses are based on sapphire ball lenses or Gradient Index lens elements.However, lenses that are on the same scale as the single-mode fiber itself have not been previously realized. This paper introduces an optical lens element that fits into the single-mode optical ferrule, without any modifications to the connector package. This approach offers substantial performance and cost benefits over other methods.Both theoretical and experimental results are presented.

This paper describes the technical approach and progresses of the POINT program. This project is a collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University and University of California at San Diego, sponsored by DARPA/ETO to develop affordable optoelectronic packaging and interconnect technologies for board and backplane applications. In this paper, we report the development of a backplane interconnect structure using polymer waveguides to an interconnect length of 280 mm to demonstrate high density and high speed interconnect, and the related technical development efforts on: (a) a high density and high speed VCSEL array packaging technology that employs planar fabrication and batch processing for low-cost manufacturing, (b) passive alignment techniques for reducing recurrent cost in optoelectronic assembly, (c) low-cost optical polymers for board and backplane level interconnects, and (d) CAD tools for modeling multimode guided wave systems and assisting optoelectronic packaging mechanical design.

The coupling of a vertical cavity surface emitting laser (VCSEL) array into an array of multimode polymer waveguides through a 45 degree endface mirror is investigated. A coupling model for the VCSEL and waveguide interface is developed and compared with our experimental results.

The Polymer Optical Interconnect Technology (POINT) represents a major collaborative effort among GE, Honeywell, AMP, AlliedSignal, Columbia University and the University of California at San Diego (UCSD), sponsored by ARPA, in developing affordable optoelectronic module packaging and interconnect technologies for board- and backplane- level optical interconnect applications for a wide range of military and commercial applications. The POINT program takes a novel development approach by fully leveraging the existing electronic design, processing, fabrication and module packaging technologies to optoelectronic module packaging. The POINT program further incorporates several state-of-the-art optoelectronic technologies that include high-speed VCSEL for multichannel array data TM transmission; flexible optical polymers such as Polyguide or coupling of device-to-fiber using a passively alignment process; a low-loss polymer for backplane interconnect to provide a high I/O density; low-cost diffractive optical elements (DOE) for board-to-backplane interconnect; and use of molded MT array ferrule to reduce overall system size, weight, and cost. In addition to further reducing design and fabrication cycle times, computer simulation tools for optical waveguide and mechanical modeling will be advanced under the POINT program.

The iterative discrete on-axis (IDO) method1 is a computer generated hologram (CGH) encoding algorithm that employs iterative optimization routines such as simulated annealing. The IDO method has been used for the optimization of large 2-D even numbered, spot arrays for optical interconnect applications. Even numbered spot arrays have several performance advantages including low sensitivity to fabrication errors, and reduced computational complexity. Binary and multiple phase level CGHs have been designed and fabricated. Intensity and/or phase of the individual output pixels can be controlled. Methods to decrease the computation time, similar to the recursive mean squares error function described in Ref. 2, have been developed for this use. Diffraction efficiencies of up to 84% have been achieved for generating spot arrays with 100–1024 points.

A hybrid-algorithm has been developed that uses the concept of a rapid recursive mean-squared-error (RMSE) function combined with the annealed, multiphase, on-axis capabilities of iterative discrete on-axis (IDO) encoding. High diffraction efficiency and computational speed are obtained through the use of the RMSE algorithm with a constant weighting coefficient in the error function and an iterative initial process for determining phase codes in the output plane. Results for large even spot arrays are presented, and comparisons are made for diffraction efficiency, spot uniformity, and computation speed between the original IDO and the RMSE-based IDO encoding.