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Showing papers on "Proximity effect (electron beam lithography) published in 2004"


Proceedings ArticleDOI
18 Oct 2004
TL;DR: In this paper, the mechanism of proximity effect is discussed through Monte Carlo simulation of the electron scattering processes and effective approaches for proximity effect correction are proposed, which can effectively reduce the proximity effect through improving mask design, optimizing processes conditions and utilizing proximity effect corrections software.
Abstract: Proximity effect is the most severe factor that influences the exposure resolution of electron beam. In this paper, the mechanism of proximity effect is discussed through Monte Carlo simulation of the electron scattering processes. And effective approaches of proximity effect correction are proposed. The theoretical results of Monte Carlo simulation and experimental results show that proximity effect is determined by many factors, in addition to the shape, size and packing density of patterns, proximity effect is also dependent on processes conditions. Only on the basis of optimizing the processes conditions and mask design, the expectant purpose of proximity effect correction by software can be achieved. Proximity effect is effectively reduced through improving mask design, optimizing processes conditions and utilizing proximity effect correction software.

164 citations


Patent
10 May 2004
TL;DR: In this article, a photomask has a pattern with compensation features that alleviate patterning variations due to the proximity effect and depth of focus concerns during photolithography, and the compensation features are disposed near isolated or outermost lines of a device pattern.
Abstract: A photolithography and etch process sequence includes a photomask having a pattern with compensation features that alleviate patterning variations due to the proximity effect and depth of focus concerns during photolithography. The compensation features may be disposed near isolated or outermost lines of a device pattern. A photoresist pattern is formed to include the compensation features and the pattern etched to form a corresponding etched pattern including the compensation features. After etching, a protection material is formed over the layer and a trim mask is used to form a further photoresist pattern over the protection material. A subsequent etching pattern etches the protection material and removes the compensation features and results in the device lines being formed unaffected by proximity effects. Flare dummies may additionally be added to the mask pattern to increase pattern density and assist in endpoint detection. Flare dummies, like the compensation features, are subsequently removed by a photolithography and etching process sequence.

47 citations


Journal ArticleDOI
TL;DR: In this article, a focused megaelectronvolt (MeV) proton beam writing of poly-(methyl methacrylate) positive resist combined with metal lift-off was used to achieve a few nanometres gap.
Abstract: Metal electrode structures for biosensors with a high spatial density and similar to85 nm gaps have been produced using focused megaelectronvolt (MeV) proton beam writing of poly-(methyl methacrylate) positive resist combined with metal lift-off. The minimal proximity exposure and straight proton trajectories in (similar to100 nm) resist layers for focused MeV proton beam writing are strongly indicative that ultimate electrode gap widths approaching a few nanometres are achievable.

41 citations


Journal ArticleDOI
TL;DR: In this paper, the NERIME (negative resist image by dry etching) process combines these advantages due to the incorporation of focused Ga ion beam (Ga FIB) exposure, near UV exposure, silylation and dry development process steps.

19 citations


Patent
28 Sep 2004
TL;DR: In this paper, the authors proposed a partial collective exposure method to correct the proximity effect in electron beam exposure, where the size of the openings varies at a predetermined rate in the order of arrangement.
Abstract: PROBLEM TO BE SOLVED: To provide an electron beam exposure mask, and electron beam exposure method and device wherein proximity effect in electron beam exposure is corrected by partial collective exposure method. SOLUTION: The electron beam exposure device comprises an electron beam generating section, an electron beam exposure mask having openings for correcting proximity effect arranged such that the size of the openings varies at a predetermined rate in the order of arrangement, a mask deflecting section for deflecting the electron beam on the exposure mask, a substrate deflecting section for projecting the electron beam passed through the exposure mask while deflecting, and a section for controlling the deflection amount at the mask deflecting section and the substrate deflecting section. COPYRIGHT: (C)2006,JPO&NCIPI

14 citations


Patent
06 Jan 2004
TL;DR: In this article, a circuit pattern lithography system which can reduce the computing time by alleviating the load on the electronic computer which computes for correcting the proximity effect and loading effect and can appropriately correct those effects by adjusting exposure when manufacturing photomask blanks.
Abstract: PROBLEM TO BE SOLVED: To provide a circuit pattern lithography system which can reduce the computing time by alleviating the load on the electronic computer which computes for correcting the proximity effect and loading effect and can appropriately correct those effects by adjusting exposure when manufacturing photomask blanks on which circuit patterns are drawn. SOLUTION: A dividing section 23 divides the circuit pattern, and an effect map creating section 24 creates an effect map. A proximity effect amount calculating section 25 obtains a proximity effect amount, and a loading effect correction amount calculating section 26 computes a loading effect amount correction amount. Further, an exposure amount calculating means calculates the exposure amount for each micro loading effect block. COPYRIGHT: (C)2005,JPO&NCIPI

13 citations


Patent
21 Jul 2004
TL;DR: In this article, the authors propose an exposure method that can be carried out without changing a mask even if the mask is bias-corrected with an improper amount of correction to a proximity effect.
Abstract: PROBLEM TO BE SOLVED: To carry out exposure so that a desired pattern can be obtained without changing a mask even if the mask is bias-corrected with an improper amount of correction to a proximity effect. SOLUTION: The exposure method comprises a first exposure process (S106) wherein a first wafer is exposed to a focused electron beam using a mask wherein a bias is applied to a prescribed region thereof; and an n-th exposure process (S118) wherein, in the case that the pattern width of a pattern transferred from the mask starting from the bias-applied region and formed on a substrate is not consistent with a desired pattern since an amount of the bias is too large, an n-th wafer is exposed to an electron beam which is defocused to obtain a defocusing amount where the pattern width becomes consistent with the desired one. Wafers exposed after obtaining the defocusing amount are exposed to an electron beam defocused by the obtained defocusing amount to adjust the dimension of a pattern formed on the wafer to be exposed after the defocusing amount is obtained. COPYRIGHT: (C)2006,JPO&NCIPI

12 citations


Patent
Byeong-soo Kim1, Han-Ku Cho1
08 Nov 2004
TL;DR: In this paper, the phase edge effect is used to reduce the intensity of light at the boundary of two transmitting regions from through transmitted light, where the phase difference has a phase difference and the diffraction pattern of the isolated pattern is the same as that of the dense pattern.
Abstract: A mask corrects for an optical proximity effect (OPE). A dummy pattern having a phase-edge effect is formed on a mask substrate. The phase-edge effect reduces the intensity of light at the boundary of two transmitting regions from through transmitted light has a phase difference. A pattern can then be formed in a photolithographic process using the phase-edge effect. A difference between “isolated” and “dense” patterns formed on a wafer can be reduced by forming a dummy pattern in an isolated pattern region of the mask and making the diffraction pattern of the isolated pattern the same as that of the dense pattern, thereby improving the total focus margin. Because the intensity of light is reduced at the boundary between a first region in which the phase of the transmitted light is 0° and a second region in which the phase of the transmitted light is 180°, for example, a photoresist layer is not photosensitized.

11 citations


Journal ArticleDOI
TL;DR: In this paper, a 100 keV e-beam lithography system was used for the fabrication of the high resolution x-ray mask, and the experimental results proved the feasibility of reproducing submicron features with an aspect ratio of 12.
Abstract: With a view to meeting the requirements of high resolution microelectromechanical system applications, we studied high resolution (submicron scale) and high aspect ratio pattern fabrication through x-ray lithography As a critical part of the x-ray lithography, an x-ray mask should have the properties of high resolution and being a thick absorber To decrease the scattering effect, a 100 keV e-beam lithography system was used for the fabrication of the high resolution x-ray mask 3 ?m thick PMMA (polymethylmethacrylate) resist was patterned and 2 ?m thick gold was electroplated onto the patterned resist to form the x-ray mask Scanning electron microscopy analysis showed that the sidewall and pattern uniformity were sufficient and that the proximity effect did not play a significant role for the selected test patterns 6 ?m thick PMMA resist was exposed by the x-ray mask; the experimental results proved the feasibility of reproducing submicron features 05 ?m nested patterns with an aspect ratio of 12 were fabricated by this approach

9 citations


Patent
28 Jan 2004
TL;DR: In this article, a method for correcting a proximity effect applied to a dose of an electron beam exposure, including classifying an underlying pattern of a level underlying a thin film layer, was proposed.
Abstract: A method for correcting a proximity effect applied to a dose of an electron beam exposure, includes classifying an underlying pattern of a level underlying a thin film layer; dividing a processing pattern to be transferred on the thin film layer into a first pattern overlapping with the underlying pattern and a second pattern which does not overlap with the underlying pattern according to the classified underlying pattern; calculating a pattern area density for the first and second patterns in a unit region; and calculating a corrected dose for the processing pattern according to the pattern area density.

8 citations


Journal ArticleDOI
TL;DR: In this article, a detailed study of the electron beam lithography process is presented using two simulation methods: one based on Monte Carlo simulation and another based on the Boltzmann transport equation.
Abstract: High temperature superconducting (HTS) devices offer significant performance (higher signal to noise ratio, sensitivity etc) improvement over conventional devices, becoming more prominent when device dimensions are scaled down. A typical technology for the fabrication of devices with very small critical dimensions is electron beam lithography. In the current work, a detailed study of the electron beam lithography process is presented using two simulation methods: one based on Monte Carlo simulation and one based on the Boltzmann transport equation. Simulation energy deposition results are compared with experimental ones in the case of Si and superconducting substrates for the first time, with satisfactory agreement found. The experimental data for statistical distributions of the scattered electrons were calculated in the case of an epoxy based chemically amplified resist film deposited on Si and on Y Ba2Cu3O7−δ/SrTiO3. The substrate strongly influences the distribution of the backscattered electrons due to the different effective atomic number and the mass densities of the substrate and YBCO layer are studied. It is shown that the decrease of the effective atomic numbers of the substrates (MgO and SrTiO3 in comparison with YBCO) leads to an increase in the external proximity effect obtained in regions far from the point of beam incidence on the resist (2 µm for 25 keV and 10–11 µm for 75 keV in the case of MgO). On MgO and SrTiO3 substrates the proximity effect is lower than on YBCO substrate (bulk YBCO) in regions near to the point of beam incidence. Using simulation tools, accurate prediction of final resist profiles (after development) over a wide exposure dose range of dense sub-quarter-micron structures is performed for both Si and superconducting substrates.

Journal ArticleDOI
TL;DR: In this paper, the influence of Coulomb effects on electron projection lithography (EPL) was discussed and the effect of the Coulomb effect on the resolution and dose margin was investigated.
Abstract: Electron projection lithography (EPL) is an attractive candidate for next-generation lithography. In EPL, Coulomb effects consisting of a global space charge and stochastic Coulomb effect are a concern because of the huge beam current exposure required. We discuss the influence of the Coulomb effects in EPL. Proximity and Coulomb effects are known to degrade resolution and dose margin. To discriminate between the influence of Coulomb effects on exposure results from those of the proximity effect, we used complementary exposures. We found that a resolution of 1:1 L&S at a 6.9μA beam current on a wafer was 100nm and at a 1.3μA beam current was 65–70nm. These results roughly met specifications of the EPL system, NSR-EB1A. We found, however, that the beam blur varied within a subfield, and the difference between CD at 0.5 and 6.4μA at 100nm was 12nm due to the different beam blur, even if the space-charge effect was corrected by refocusing. To achieve accurate CD control, the proximity effect must thus be cor...

Patent
29 Oct 2004
TL;DR: In this article, the authors proposed a method to evaluate a difference between design data and a formed resist pattern in detail by using observation data of the resist pattern formed through a semiconductor lithography process.
Abstract: PROBLEM TO BE SOLVED: To provide an SEM system for length measurement capable of high-accuracy and precise OPC (optical proximity correction) evaluation which is important from now on with advancement in a finer semiconductor design pattern, and to provide an evaluation system for a circuit pattern feature and a method therefor. SOLUTION: In order to evaluate a difference between design data and a formed resist pattern in detail by using observation data of the resist pattern formed through a semiconductor lithography process, the design data and the observation data of the resist pattern are superposed to calculate a one-dimensional or two-dimensional geometric characteristic value expressing the difference between them. However, the design data and the resist pattern sometimes differ much in features due to an OPE (optical proximity effect). Therefore, in order to stably and highly accurately superpose the design data and the observation data of the resist pattern, a transfer pattern to be formed through the photomask data used for the exposure and the exposure conditions is calculated by using an exposure simulator, and the transfer pattern is superposed on the observation data of the actual resist pattern. COPYRIGHT: (C)2006,JPO&NCIPI

Journal ArticleDOI
TL;DR: In this article, the authors describe a method, utilizing the proximity effect in electron beam lithography, suitable for fabricating silicon dots and devices, and demonstrate the electronic characteristics of the Si single-electron transistor.
Abstract: In this letter, we shall describe a method, utilizing the proximity effect in electron beam lithography, suitable for fabricating silicon dots and devices, and demonstrate the electronic characteristics of the Si single-electron transistor. The drain current (Id) of the device oscillates against gate voltage. The electrical characteristics of the single-electron transistor were observed to be consistent with the expected behavior of electron transport through gated quantum dots, at up to 150K. The dependence of the electrical characteristics on the dot size reveals that the Id oscillation follows from the Coulomb blockade by poly-Si grains in the poly-Si dot. The method of fabrication of this device is completely compatible with complementary metal–oxide–semiconductor technology, raising the possibility of manufacturing large-scale integrated nanoelectronic systems.

Proceedings ArticleDOI
26 Apr 2004
TL;DR: A distributed implementation of proximity effect correction, and static and dynamic load balancing schemes which attempt to minimize execution time of distributed proximity effect Correction by considering heterogeneity of a cluster and nonuniformity in a circuit pattern are described.
Abstract: Summary form only given. Electron-beam lithography is one of the techniques used in transferring circuit patterns onto substrates. Proximity effect caused by electron scattering imposes a severe limitation on the ultimate spatial resolution attainable by e-beam lithography. Therefore, proximity effect correction is essential particularly for fine-feature, high-density circuit patterns. Proximity effect correction is very time-consuming due to intensive computation required in the correction procedure and a large size of circuit pattern data to be processed. Therefore, it is an ideal candidate for distributed computing where the otherwise-unused CPU cycles of a number of computers on a network (cluster) can be efficiently utilized. One of the characteristics of such a cluster is its heterogeneity, i.e., the available computing power varies with computer and/or time. This variation may degrade performance of distributed computing significantly. We describe a distributed implementation of proximity effect correction, and static and dynamic load balancing schemes which attempt to minimize execution time of distributed proximity effect correction by considering heterogeneity of a cluster and nonuniformity in a circuit pattern. Also, experimental results obtained on a cluster of Sun workstations shared by multiple users are presented.

Journal ArticleDOI
TL;DR: In this article, the e-beam proximity effect on silicon wafers with thin metallic films of varying thickness has been analyzed using an automated CD-SEM, and the results showed that the CD was found to change at a rate of 0.17nm per degree of break-point angle for the Ni films, and 0.25nm for Ta.
Abstract: We have characterized the e-beam proximity effect as it applies to the write pole break-point angle of magnetic recording heads. These narrow isolated negative resist lines have been measured using an automated CD-SEM. The CD data allows us to quantify the e-beam proximity effect on silicon wafers with thin metallic films of varying thickness. Nickel and tantalum have atomic numbers of 28 and 73, respectively, and this difference is quantified by the increase in the CD of the Ta films compared to Ni. The CD was found to change at a rate of 0.17nm per degree of break-point angle for the Ni films, and 0.25nm per degree for Ta. We have analyzed the experimental data by comparing it to two relevant models. First, we compare the data to the traditional expression used to describe e-beam exposure, a double Gaussian. From both the CD data and the double Gaussian, we calculate a proximity effect term we refer to as the dose fraction. This dose fraction has a linear relationship with the “eta” parameter, which als...

Journal Article
TL;DR: In this paper, a computer aided proximity effect correction system is proposed to verify the pattern layout and eliminate the proximity effect, based on the evaluated results, the effectiveness of the system is confirmed experimentally.
Abstract: Reflected light from step coverage causes fatal pattern defects in photolithography. The resist pattern defects are caused by the extra exposure from the highly reflective stepped substrate, such as breaks in the pattern of the aluminum layer. The problem is significant when the patterns in the different layers are near each other. We named this problem the proximity effect. The specific design rules such as the space between the resist pattern and the steps on the substrate are evaluated by simulation and experiment. Based on the evaluated results, we propose a computer aided proximity effect correction system to verify the pattern layout and eliminate the proximity effect. The effectiveness of the system is confirmed experimentally.


Patent
08 Apr 2004
TL;DR: In this paper, an electron beam drawing method was proposed to stabilize a blaze shape by carrying out drawing with a dosage according to the pitch width of blazes while taking into consideration influence of proximity effect by back scattering.
Abstract: PROBLEM TO BE SOLVED: To provide an electron beam drawing method, a manufacturing method for a metal mold for an optical element, a manufacturing method for the optical element, and an electron beam drawing device that can stabilize a blaze shape by carrying out drawing with a dosage according to the pitch width of blazes while taking into consideration influence of proximity effect by back scattering SOLUTION: A base material is irradiated with an electron beam and the electron beam is scanned with a specified dosage to form a plurality of blazes including different pitches on at least one surface of the base material and when a side wall part which rises from a section position of the blazes and an oblique part connecting the peak of the side wall part and the bottom of the side wall part of another adjacent blaze are formed in at least one pitch of the blazes, the dosage is found based upon a 1st dose function F(X) when the blaze pitch COPYRIGHT: (C)2004,JPO

Patent
12 Aug 2004
TL;DR: In this article, a reticle 11 made of a glass substrate as a photomask is provided with a light shielding film pattern relating to formation of elements and integrated circuits on a semiconductor wafer as well as an auxiliary pattern 13 which corrects degeneracy of lines due to influences of the optical proximity effect during exposure in an isolated pattern P1 in at least a sparse pattern region.
Abstract: PROBLEM TO BE SOLVED: To provide a method for manufacturing a photomask and a pattern by which degeneracy of lines in an isolated fine exposure pattern can be easily improved and reliability is improved, and to provide a semiconductor device. SOLUTION: A reticle 11 made of a glass substrate as a photomask is provided with a light shielding film pattern 12 relating to formation of elements and integrated circuits on a semiconductor wafer as well as with an auxiliary pattern 13 which corrects degeneracy of lines due to influences of the optical proximity effect during exposure in an isolated pattern P1 in at least a sparse pattern region, as shown in Figures (a) and (b). The auxiliary pattern 13 comprises a pattern for correcting the optical proximity effect by engraving a specified region of the reticle 11 in such a manner that the pattern is parallel to at least a specified line part. The auxiliary pattern 13 forms an etching region where the profile of light to compensate the diffracted part of light on the line edge is controlled as shown in Fig. (c). COPYRIGHT: (C)2004,JPO&NCIPI

Patent
28 Jul 2004
TL;DR: In this article, the correction portion data are created to specify a correction portion in a layout pattern where a figure is to be modified to correct an optical proximity effect based on design pattern data.
Abstract: PROBLEM TO BE SOLVED: To accurately and rapidly correct an optical proximity effect. SOLUTION: Correction portion data are created (S4, S6) to specify a correction portion in a layout pattern where a figure is to be modified to correct an optical proximity effect based on design pattern data. Along with the above steps, width-corrected pattern data as the data after correcting the optical proximity effect relating to width are created (S8, S10) by sliding the outline of the layout pattern shown by the design pattern data. Then correction figure data to modify the figure of a correction portion to correct the optical proximity effect are created based on the design pattern data, and the obtained correction figure data are compounded in the width-corrected pattern data by using the correction portion data (S12, S14). Thus, entirely corrected pattern data showing a layout pattern after correcting the optical proximity effect can be created. COPYRIGHT: (C)2006,JPO&NCIPI

01 Jan 2004
TL;DR: In this paper, a new resist model calibration procedure and its implementation in LithoCruiser is described, which is used to perform simultaneous optimization for numerical aperture (NA), mask OPC, and illumination profile with built-in manufacturing constraints for ASML illumination diffractive optical elements (DOE).
Abstract: We describe a new resist model calibration procedure and its implementation in LithoCruiser . In addition to the resist calibration, LithoCruiser is used to perform simultaneous optimization for numerical aperture (NA), mask OPC, and illumination profile with built-in manufacturing constraints for ASML illumination diffractive optical elements (DOE). This calibration procedure uses a global optimization algorithm for resist parameter tuning, matching the simulated and measured 2D resist contours at a user-defined multiple CD sampling across the selected developed 2D resist patterns. Using lumped parameter type resist models and vector high-NA simulation engine, this resist calibration procedure showed an excellent calibration capability of max CD error range < ±4nm for the CPL 70nm DRAM patterns. Calibration results for CPL 130nm contact hole patterns are also included in this manuscript. Dependency of the calibrated model parameters on lithography process (i.e., Quasar, C-Quad illumination and at different defocus) and further improvements to a more predictable resist model are discussed.

Patent
31 Mar 2004
TL;DR: In this article, a method of testing a mask pattern is proposed, which includes applying optical proximity-effect compensation to a first pattern to be tested and to be formed onto a mask layer, to thereby form a mask mask pattern of the mask layer.
Abstract: A method of testing a mask pattern, includes applying optical proximity-effect compensation to a first pattern to be tested and to be formed onto a mask layer, to thereby form a mask pattern of the mask layer, dividing the first pattern into a plurality of areas in accordance with a second pattern to be formed onto another mask layer, determining sampling points on an edge of the first pattern, determining a test standard for each of the areas, simulating a resist pattern formed on a resist by exposing the resist to a light through the mask pattern, and checking whether a dimensional gap between the first pattern and the resist pattern at each of the sampling points is within a test standard associated with an area to which each of the sampling points belongs, wherein test standards for first and second areas among the areas are different from each other.

Journal ArticleDOI
01 Jan 2004
TL;DR: In this paper, a Si stencil mask for corrected data was fabricated and then exposed using an electron-beam stepper, which resulted in high linewidth controllability and uniformity of critical dimension.
Abstract: We experimentally evaluated the overall performance of our proximity effect correction method in electron projection lithography. A Si stencil mask for corrected data was fabricated and then exposed using an electron-beam stepper. Shape modification resulted in high linewidth controllability and uniformity of critical dimension (CD) even when the pattern density changed. The deviation in linewidth was 6.6 nm in linearity, and 4.7 nm in the pattern density dependence of a 100 nm line. As well as shape modification, we reduced the pattern density of large patterns by replacing the interior area with mesh patterns in order to produce isolated space patterns. The meshes were well fabricated on the mask. Isolated spaces were successfully formed without resolving the mesh patterns on a resist.

Patent
Byeong-soo Kim1, Han-Ku Cho1
08 Nov 2004
TL;DR: In this paper, the phase edge effect is used to reduce the intensity of light at the boundary of two transmitting regions from through transmitted light, where the phase difference has a phase difference and the diffraction pattern of the isolated pattern is the same as that of the dense pattern.
Abstract: A mask corrects for an optical proximity effect (OPE). A dummy pattern having a phase-edge effect is formed on a mask substrate. The phase-edge effect reduces the intensity of light at the boundary of two transmitting regions from through transmitted light has a phase difference. A pattern can then be formed in a photolithographic process using the phase-edge effect. A difference between “isolated” and “dense” patterns formed on a wafer can be reduced by forming a dummy pattern in an isolated pattern region of the mask and making the diffraction pattern of the isolated pattern the same as that of the dense pattern, thereby improving the total focus margin. Because the intensity of light is reduced at the boundary between a first region in which the phase of the transmitted light is 0° and a second region in which the phase of the transmitted light is 180°, for example, a photoresist layer is not photosensitized.