Allen Carroll - Academia.edu (original) (raw)
Papers by Allen Carroll
Journal of Vacuum Science and Technology
ABSTRACT Submicron e‐beam lithography requires that successive levels be accurately registered to... more ABSTRACT Submicron e‐beam lithography requires that successive levels be accurately registered to each previously processed pattern on a wafer. Using a Perkin–Elmer manufacturing electron‐beam exposure system (MEBES)R, we estimate the ability of an automated three‐mark registration system to correct for distortion created by typical silicon processing. The results show that this registration system is capable of tracking process‐induced distortions typically to within 0.15 μm everywhere on 64‐mm‐diam silicon wafers.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures
ABSTRACT A direct write electron beam lithography system has been constructed which is capable of... more ABSTRACT A direct write electron beam lithography system has been constructed which is capable of writing 0.5 μm VHSIC patterns at a rate of 4 to 25 four-inch wafer levels per hour. The several key subsystems which permit this increase in performance over existing systems are (1) A variable shaped beam which exposes rectangular or triangular shapes from 0.5 to 2.0 μm in size at a current density up to 200 A/cm2; (2) an all digital, 100 MHz pattern generator with optical couplers for high speed, low noise data processing; (3) a unique deflection system with specially designed 18 bit digital to analog converters and ultralinear amplifiers; (4) a mechnaical state capable of 10 cm/s speed and 0.8 g acceleration, under microprocessor control, providing write‐while‐moving capability and synchronization with the pattern generator; and (5) a wafer handler system for cassette‐to‐cassette input/output; and (6) a complimentary software package which constructs files with the necessary data compaction for rapid transmission and proximity correction for proper exposure.
Ph D Thesis Cornell Univ Ithaca Ny, 1976
Integration over energy fluctuations of successively smaller size, and the computation of effecti... more Integration over energy fluctuations of successively smaller size, and the computation of effective Hamiltonians which reflect the effects of the fluctuations which have been integrated out are included in a renormalization group method used in qualitative analyses of high-energy small-angle scattering. Model field theories based on scalar cu phi theory and quantum electrodynamics (QED) are described, and details of the integration procedure are discussed in the context of these model systems. Simple recursion relations which sum the logarithms associated with ladder graphs in cu phi theory and with tower graphs in QED are demonstrated. The recursion relations for QED are shown to generate an infinite set of marginal interactions, all of which accumulate logarithms; the existence of these marginal interactions accounts for the complexity of previous analyses of high-energy scattering.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1985
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1985
22nd Annual BACUS Symposium on Photomask Technology, 2002
ABSTRACT The recently installed Sigma7100 laser pattern generator brings a new concept into photo... more ABSTRACT The recently installed Sigma7100 laser pattern generator brings a new concept into photomask manufacturing. The spatial light modulator (SLM) technology enables 2D patterning using commercially available 248 nm lasers. This wavelength shift from the 413 nm wavelength of the Omega6000 scanning laser pattern generators facilitates the high resolution needed for 100 nm mask production. In addition, the partially coherence of the 2D patterning further enhances CD linearity and edge acuity. The rapidly increasing mask costs are partially attributed to increasing photomask writing times. These tend to increase as feature density increases with the roadmap, which is a challenge for any pattern generator with a limited number of writing beams. Instead, the SLM technology relies on the massive parallelism of one million micromirrors in combination with gray-scale control for fine addressing. A real-time FPGA-based data-rendering engine matches the speed. The result is pattern generation with high resolution at manageable mask writing times
Optical Microlithography XV, 2002
ABSTRACT Micronic is developing a massively parallel pattern generation system based on a micro-m... more ABSTRACT Micronic is developing a massively parallel pattern generation system based on a micro-mechanical spatial light modulator (SLM). The electro-mechanical and optical properties of the micromirrors in the SLM can vary from one to another and over time. Therefore the response of each mirror must be calibrated, with accuracy sufficient to maintain CD uniformity requirements. We present a practical method for performing this calibration which greatly improves the micromirror grayscale uniformity and reduces CD error contribution from the SLM to less than 2nm.
Journal of Vacuum Science and Technology, 1981
ABSTRACT The most important tool in computing proximity effect compensation for electron‐beam lit... more ABSTRACT The most important tool in computing proximity effect compensation for electron‐beam lithographic patterns is a powerful and general facility for correcting small subpatterns. In this paper, we propose a solution method for the subpattern correction problem which has significant advantages over the techniques currently in use. The problem is shown to be amenable to the techniques of mathematical optimization. This permits proximity effect compensation to be adapted to the needs of a particular resist, device pattern, process step, or lighographic equipment.
Physical Review D, 1979
ABSTRACT A generalization of Hamiltonian perturbation theory is presented. The method solves a lo... more ABSTRACT A generalization of Hamiltonian perturbation theory is presented. The method solves a low-energy sector of the theory exactly while systematically accounting for higher-energy states perturbatively. It produces an expansion for the mass matrix of the low-energy sector. In applications to lattice theories, the mass matrix can be extrapolated to the continuum limit using matrix Padé approximants. The method is illustrated for a lattice potential model and fast convergence to the continuum limit is verified numerically.
Alternative Lithographic Technologies III, 2011
REBL (Reflective Electron Beam Lithography) is a program for the development of a novel approach ... more REBL (Reflective Electron Beam Lithography) is a program for the development of a novel approach for highthroughput maskless lithography. The program at KLA-Tencor is funded under the DARPA Maskless Nanowriter Program. A DPG (digital pattern generator) chip containing over 1 million reflective pixels that can be individually turned on or off is used to project an electron beam pattern onto
Alternative Lithographic Technologies, 2009
REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam ... more REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam direct write maskless lithography. The system is specifically targeting 5 to 7 wafer levels per hour throughput on average at the 45 nm node, with extendibility to the 32 nm node and beyond. REBL incorporates a number of novel technologies to generate and expose lithographic patterns at estimated throughputs considerably higher than electron beam lithography has been able to achieve as yet. A patented reflective electron optic concept enables the unique approach utilized for the Digital Pattern Generator (DPG). The DPG is a CMOS ASIC chip with an array of small, independently controllable cells or pixels, which act as an array of electron mirrors. In this way, the system is capable of generating the pattern to be written using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve the capability of high throughput for sparse pattern wafer levels. The exposure method utilized by the DPG was emulated on a Vistec VB-6 in order to validate the gray level exposure method used in REBL. Results of these exposure tests are discussed.
Alternative Lithographic Technologies VI, 2014
ABSTRACT Reflective electron-beam lithography (REBL) employs a novel device to impress pattern in... more ABSTRACT Reflective electron-beam lithography (REBL) employs a novel device to impress pattern information on an electron beam. This device, the digital pattern generator (DPG), is an array of small electron reflectors, in which the reflectance of each mirror is controlled by underlying CMOS circuitry. When illuminated by a beam of low-energy electrons, the DPG is effectively a programmable electron-luminous image source. By switching the mirror drive circuits appropriately, the DPG can ‘scroll’ the image of an integrated circuit pattern across its surface; and the moving electron image, suitably demagnified, can be used to expose the resist-coated surface of a wafer or mask. This concept was first realized in a device suitable for 45 nm lithography demonstrations. A next-generation device has been designed and is presently nearing completion. The new version includes several advances intended to make it more suitable for application in commercial lithography systems. We will discuss the innovations and compromises in the design of this next-generation device. For application in commercially-practical maskless lithography at upcoming device nodes, still more advances will be needed. Some of the directions in which this technology can be extended will be described.
Alternative Lithographic Technologies VI, 2014
ABSTRACT KLA-Tencor is currently developing Reflective Electron Beam Lithography (REBL), targeted... more ABSTRACT KLA-Tencor is currently developing Reflective Electron Beam Lithography (REBL), targeted as a production worthy multiple electron beam tool for next generation high volume lithography. The Digital Pattern Generator (DPG) integrated with CMOS and MEMS lenslets is a critical part of REBL. Previously, KLA-Tencor reported on progress towards a REBL tool for maskless lithography below the 10 nm technology node. However, the MEMS lenslet structure suffered from charging up during writing, requiring the usage of a charge drain coating. Since then, the TSMC multiple e-beam team and the KLA-Tencor REBL team have worked together to further develop the DPG for direct write lithography. In this paper, we introduce a hollow-structure MEMS lenslet array that inherently prevents charging during writing, and preliminary verification results are also presented.
Alternative Lithographic Technologies IV, 2012
ABSTRACT REBL (Reflective Electron Beam Lithography) is a novel concept for high speed maskless p... more ABSTRACT REBL (Reflective Electron Beam Lithography) is a novel concept for high speed maskless projection electron beam lithography. Originally targeting 45 nm HP (half pitch) under a DARPA funded contract, we are now working on optimizing the optics and architecture for the commercial silicon integrated circuit fabrication market at the equivalent of 16 nm HP. The shift to smaller features requires innovation in most major subsystems of the tool, including optics, stage, and metrology. We also require better simulation and understanding of the exposure process. In order to meet blur requirements for 16 nm lithography, we are both shrinking the pixel size and reducing the beam current. Throughput will be maintained by increasing the number of columns as well as other design optimizations. In consequence, the maximum stage speed required to meet wafer throughput targets at 16 nm will be much less than originally planned for at 45 nm. As a result, we are changing the stage architecture from a rotary design to a linear design that can still meet the throughput requirements but with more conventional technology that entails less technical risk. The linear concept also allows for simplifications in the datapath, primarily from being able to reuse pattern data across dies and columns. Finally, we are now able to demonstrate working dynamic pattern generator (DPG) chips, CMOS chips with microfabricated lenslets on top to prevent crosstalk between pixels.
Journal of Vacuum Science and Technology
ABSTRACT Submicron e‐beam lithography requires that successive levels be accurately registered to... more ABSTRACT Submicron e‐beam lithography requires that successive levels be accurately registered to each previously processed pattern on a wafer. Using a Perkin–Elmer manufacturing electron‐beam exposure system (MEBES)R, we estimate the ability of an automated three‐mark registration system to correct for distortion created by typical silicon processing. The results show that this registration system is capable of tracking process‐induced distortions typically to within 0.15 μm everywhere on 64‐mm‐diam silicon wafers.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures
ABSTRACT A direct write electron beam lithography system has been constructed which is capable of... more ABSTRACT A direct write electron beam lithography system has been constructed which is capable of writing 0.5 μm VHSIC patterns at a rate of 4 to 25 four-inch wafer levels per hour. The several key subsystems which permit this increase in performance over existing systems are (1) A variable shaped beam which exposes rectangular or triangular shapes from 0.5 to 2.0 μm in size at a current density up to 200 A/cm2; (2) an all digital, 100 MHz pattern generator with optical couplers for high speed, low noise data processing; (3) a unique deflection system with specially designed 18 bit digital to analog converters and ultralinear amplifiers; (4) a mechnaical state capable of 10 cm/s speed and 0.8 g acceleration, under microprocessor control, providing write‐while‐moving capability and synchronization with the pattern generator; and (5) a wafer handler system for cassette‐to‐cassette input/output; and (6) a complimentary software package which constructs files with the necessary data compaction for rapid transmission and proximity correction for proper exposure.
Ph D Thesis Cornell Univ Ithaca Ny, 1976
Integration over energy fluctuations of successively smaller size, and the computation of effecti... more Integration over energy fluctuations of successively smaller size, and the computation of effective Hamiltonians which reflect the effects of the fluctuations which have been integrated out are included in a renormalization group method used in qualitative analyses of high-energy small-angle scattering. Model field theories based on scalar cu phi theory and quantum electrodynamics (QED) are described, and details of the integration procedure are discussed in the context of these model systems. Simple recursion relations which sum the logarithms associated with ladder graphs in cu phi theory and with tower graphs in QED are demonstrated. The recursion relations for QED are shown to generate an infinite set of marginal interactions, all of which accumulate logarithms; the existence of these marginal interactions accounts for the complexity of previous analyses of high-energy scattering.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1985
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 1985
22nd Annual BACUS Symposium on Photomask Technology, 2002
ABSTRACT The recently installed Sigma7100 laser pattern generator brings a new concept into photo... more ABSTRACT The recently installed Sigma7100 laser pattern generator brings a new concept into photomask manufacturing. The spatial light modulator (SLM) technology enables 2D patterning using commercially available 248 nm lasers. This wavelength shift from the 413 nm wavelength of the Omega6000 scanning laser pattern generators facilitates the high resolution needed for 100 nm mask production. In addition, the partially coherence of the 2D patterning further enhances CD linearity and edge acuity. The rapidly increasing mask costs are partially attributed to increasing photomask writing times. These tend to increase as feature density increases with the roadmap, which is a challenge for any pattern generator with a limited number of writing beams. Instead, the SLM technology relies on the massive parallelism of one million micromirrors in combination with gray-scale control for fine addressing. A real-time FPGA-based data-rendering engine matches the speed. The result is pattern generation with high resolution at manageable mask writing times
Optical Microlithography XV, 2002
ABSTRACT Micronic is developing a massively parallel pattern generation system based on a micro-m... more ABSTRACT Micronic is developing a massively parallel pattern generation system based on a micro-mechanical spatial light modulator (SLM). The electro-mechanical and optical properties of the micromirrors in the SLM can vary from one to another and over time. Therefore the response of each mirror must be calibrated, with accuracy sufficient to maintain CD uniformity requirements. We present a practical method for performing this calibration which greatly improves the micromirror grayscale uniformity and reduces CD error contribution from the SLM to less than 2nm.
Journal of Vacuum Science and Technology, 1981
ABSTRACT The most important tool in computing proximity effect compensation for electron‐beam lit... more ABSTRACT The most important tool in computing proximity effect compensation for electron‐beam lithographic patterns is a powerful and general facility for correcting small subpatterns. In this paper, we propose a solution method for the subpattern correction problem which has significant advantages over the techniques currently in use. The problem is shown to be amenable to the techniques of mathematical optimization. This permits proximity effect compensation to be adapted to the needs of a particular resist, device pattern, process step, or lighographic equipment.
Physical Review D, 1979
ABSTRACT A generalization of Hamiltonian perturbation theory is presented. The method solves a lo... more ABSTRACT A generalization of Hamiltonian perturbation theory is presented. The method solves a low-energy sector of the theory exactly while systematically accounting for higher-energy states perturbatively. It produces an expansion for the mass matrix of the low-energy sector. In applications to lattice theories, the mass matrix can be extrapolated to the continuum limit using matrix Padé approximants. The method is illustrated for a lattice potential model and fast convergence to the continuum limit is verified numerically.
Alternative Lithographic Technologies III, 2011
REBL (Reflective Electron Beam Lithography) is a program for the development of a novel approach ... more REBL (Reflective Electron Beam Lithography) is a program for the development of a novel approach for highthroughput maskless lithography. The program at KLA-Tencor is funded under the DARPA Maskless Nanowriter Program. A DPG (digital pattern generator) chip containing over 1 million reflective pixels that can be individually turned on or off is used to project an electron beam pattern onto
Alternative Lithographic Technologies, 2009
REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam ... more REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam direct write maskless lithography. The system is specifically targeting 5 to 7 wafer levels per hour throughput on average at the 45 nm node, with extendibility to the 32 nm node and beyond. REBL incorporates a number of novel technologies to generate and expose lithographic patterns at estimated throughputs considerably higher than electron beam lithography has been able to achieve as yet. A patented reflective electron optic concept enables the unique approach utilized for the Digital Pattern Generator (DPG). The DPG is a CMOS ASIC chip with an array of small, independently controllable cells or pixels, which act as an array of electron mirrors. In this way, the system is capable of generating the pattern to be written using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve the capability of high throughput for sparse pattern wafer levels. The exposure method utilized by the DPG was emulated on a Vistec VB-6 in order to validate the gray level exposure method used in REBL. Results of these exposure tests are discussed.
Alternative Lithographic Technologies VI, 2014
ABSTRACT Reflective electron-beam lithography (REBL) employs a novel device to impress pattern in... more ABSTRACT Reflective electron-beam lithography (REBL) employs a novel device to impress pattern information on an electron beam. This device, the digital pattern generator (DPG), is an array of small electron reflectors, in which the reflectance of each mirror is controlled by underlying CMOS circuitry. When illuminated by a beam of low-energy electrons, the DPG is effectively a programmable electron-luminous image source. By switching the mirror drive circuits appropriately, the DPG can ‘scroll’ the image of an integrated circuit pattern across its surface; and the moving electron image, suitably demagnified, can be used to expose the resist-coated surface of a wafer or mask. This concept was first realized in a device suitable for 45 nm lithography demonstrations. A next-generation device has been designed and is presently nearing completion. The new version includes several advances intended to make it more suitable for application in commercial lithography systems. We will discuss the innovations and compromises in the design of this next-generation device. For application in commercially-practical maskless lithography at upcoming device nodes, still more advances will be needed. Some of the directions in which this technology can be extended will be described.
Alternative Lithographic Technologies VI, 2014
ABSTRACT KLA-Tencor is currently developing Reflective Electron Beam Lithography (REBL), targeted... more ABSTRACT KLA-Tencor is currently developing Reflective Electron Beam Lithography (REBL), targeted as a production worthy multiple electron beam tool for next generation high volume lithography. The Digital Pattern Generator (DPG) integrated with CMOS and MEMS lenslets is a critical part of REBL. Previously, KLA-Tencor reported on progress towards a REBL tool for maskless lithography below the 10 nm technology node. However, the MEMS lenslet structure suffered from charging up during writing, requiring the usage of a charge drain coating. Since then, the TSMC multiple e-beam team and the KLA-Tencor REBL team have worked together to further develop the DPG for direct write lithography. In this paper, we introduce a hollow-structure MEMS lenslet array that inherently prevents charging during writing, and preliminary verification results are also presented.
Alternative Lithographic Technologies IV, 2012
ABSTRACT REBL (Reflective Electron Beam Lithography) is a novel concept for high speed maskless p... more ABSTRACT REBL (Reflective Electron Beam Lithography) is a novel concept for high speed maskless projection electron beam lithography. Originally targeting 45 nm HP (half pitch) under a DARPA funded contract, we are now working on optimizing the optics and architecture for the commercial silicon integrated circuit fabrication market at the equivalent of 16 nm HP. The shift to smaller features requires innovation in most major subsystems of the tool, including optics, stage, and metrology. We also require better simulation and understanding of the exposure process. In order to meet blur requirements for 16 nm lithography, we are both shrinking the pixel size and reducing the beam current. Throughput will be maintained by increasing the number of columns as well as other design optimizations. In consequence, the maximum stage speed required to meet wafer throughput targets at 16 nm will be much less than originally planned for at 45 nm. As a result, we are changing the stage architecture from a rotary design to a linear design that can still meet the throughput requirements but with more conventional technology that entails less technical risk. The linear concept also allows for simplifications in the datapath, primarily from being able to reuse pattern data across dies and columns. Finally, we are now able to demonstrate working dynamic pattern generator (DPG) chips, CMOS chips with microfabricated lenslets on top to prevent crosstalk between pixels.