Showing papers on "Proximity effect (electron beam lithography) published in 2001"

Impact of acid/quencher behavior on lithography performance

Abstract: To describe complex acid/quencher interaction and their mutual diffusion in imaging with chemically amplified resist films, our acid-quencher mutual diffusion/quenching model is implemented to the fast resist image simulator. Accuracy better than 10-nm was obtained over wide varieties of 0.13- node metal-level pattern features. The model also suggested that diffusion of quencher, as well as that of acid, significantly degrades proximity effects and MEF.

Charged particle beam exposure system

Abstract: A charged particle beam exposure system comprising: a charged particle beam emitting device which generates charged particle beams with which a substrate is irradiated, the charged particle beam emitting device generating the charged particle beams at an accelerating voltage which is lower than that at which an influence of a proximity effect occurs; an illumination optical system which adjusts a beam diameter of the charged particle beams so that density of the charged particle beams is uniform; an character aperture in which an aperture hole is formed in a shape corresponding to a desired pattern to be written; a first deflector which deflects the charged particle beams by an electrostatic field that the charged particle beams have a desired sectional shape and travel towards a desired aperture hole and which returns the charged particle beams passing through the aperture hole to an optical axis thereof; a reducing projecting optical system which forms a multi-pole lens field so that the charged particle beams passing through the character aperture substantially reduce at the same demagnification both in X and Y directions when the optical axis extends in Z directions and form an image on the substrate without forming any crossover between the character aperture and the substrate; and a second deflector which deflects the charged particle beams passing through the character aperture by means of an electrostatic field to scan the substrate with the charged particle beams.

Proximity correction simulations in ultra-high resolution x-ray lithography

Abstract: This paper follows previous demonstrations of demagnification by bias in ultra-high resolution proximity x-ray lithography. The demagnification, ×1–×6, is achieved without lenses or mirrors. Two-dimensional proximity corrections, applied to rectangular mask shapes, are simulated. A V-shaped inrigger, cut into the mask, is particularly effective. When a typical range of broadband illumination wavelengths is used, several beneficial effects are observed when the gap is held at the ‘critical condition’. Maintaining fine resolution, oscillations—due to Fresnel diffraction parallel to the longer dimension of a rectangle—are virtually eliminated, and the image intensity is made uniform by the elimination of bright spots near the ends of a rectangle.

Process dependencies of optical proximity corrections

Abstract: Optical Proximity Correction has emerged as an industry standard technique to reproduce the desired shapes on wafers as pattern dimensions are approaching the optical resolution limits. However secondary effects, if not properly controlled, may impede successful application of this technique. In order to better assess these factors we have divided the overall pattern formation process into several obvious components: The illumination system, mask, projection optics, resist system and finally etch processes. Each one of these components influences the optical proximity effects observed in the final pattern. The dependence of optical proximity corrections on the type of illumination is fairly well known and will only be touched on. Variations in the mask manufacturing process such as deviations of the mask critical dimension from its nominal value will be discussed. The type of e-beam exposure tool used to write the mask was found to have profound impact on optical proximity correction and therefore specifying the type of mask writing tool and sometimes even its writing mode to ensure reproducible results is required. Lens aberrations in the optical exposure tool and their impact were studied using aerial image simulations. Examples of optical proximity curves from different first generation tools show significant differences even between tools of the same type. Resist effects and the variations induced by modifying etch processes were investigated emphasizing that a fairly detailed control of the overall pattern formation process is necessary to successfully implement any OPC approach.

Forming method for mask pattern

Abstract: PROBLEM TO BE SOLVED: To provide a forming method for a mask pattern which corrects proximity effect by using simple algorithm reducing a computation load. SOLUTION: The intensity computation is performed on a forward scatter term and a backward scatter term of an exposure intensity distribution function, the proximity effect is corrected by varying the size of a mask pattern so that the width of an exposure intensity distribution of specific energy intensity becomes equal to design size, and an area density method is used for the backward scatter intensity computation.

Mask drawing data preparing method, preparing device and memory medium

Abstract: PROBLEM TO BE SOLVED: To improve the efficiency of pattern matching, to decrease the number of times of calculation processing of correction shapes by lithography simulation and to improve the processing speed for correction of an optical proximity effect by executing a pattern matching after conversion of a grid of input data to a larger grid. SOLUTION: The points or regions A to C for correction are extracted relating to input data, (a). Firstly, the pattern layout of the pattern matching regions disposed at the circumference of the regions for correction is extracted, (b). In succession, the grid in the pattern matching region is converted to G1 larger than the input data grid G0. After the pattern matching is executed about all the regions for correction, the classified pattern matching regions are corrected. The pattern matching is executed after the conversion to the large grid G1, by which the pattern matching regions having a difference below G1 on the input data are decided to be the same to each other and the matching efficiency can be enhanced.

Pattern transferring method using mask, halftone mask, its manufacturing method and manufacturing method of circuit substrate

Abstract: PROBLEM TO BE SOLVED: To dissolve the problem that optical proximity effect occurs as a layout pattern becomes minute and size difference due to condensation and rarefaction of the pattern occurs in a resist on a wafer without lowering light intensity and prolonging exposure time. SOLUTION: In a halftone mask in which a halftone film 2 for making light intensity distribution of exposed light sharp by shifting a phase of transmitted light is selectively provided on a transparent substrate 1, film thickness D1 of the halftone film 2 in a crowding pattern area where optical proximity effect occurs is set to a value giving phase difference of 180° between itself and light transmitted through an opening 6. On the other hand, film thickness D2 of the halftone film 2 in an isolated pattern area where no optical proximity effect occurs is set to a value which gives phase difference of 180°+α between itself and light transmitted through the opening 6 and which can eliminate size difference on the resist 4 occurred by condensation and rarefaction of the pattern due to optical proximity effect. COPYRIGHT: (C)2003,JPO

Electron-beam lithography simulation for mask making: VI. Comparison of 10- and 50-kV GHOST proximity effect correction

Abstract: GHOST uses two exposures, the primary dose and its complement, in an attempt to equalize the effects of backscattering and reduce proximity effects. Unfortunately, image contrast is reduced compared to exposures done without GHOST. A simplified raster scan theory is developed in order to examine the effects of backscattering and GHOST proximity correction on the quality of the images produced. Electron beam lithography simulation is used to examine the effect of spot size and voltage on the spot image generated in 400 nm of ZEP 7000 resist, and the effects of GHOST on proximity effects and process latitude.

Method for correcting proximity effect, reticle, and method of manufacturing device

Abstract: PROBLEM TO BE SOLVED: To provide a method by which a stored energy profile formed on the surface of a sensitive substrate caused by proximity effect and out-of-focus of an optical system can be corrected. SOLUTION: In this method, a reticle pattern is set by expanding a designed pattern to a multiple of the inverse number of the reduced scale which is used at the time of transferring the designed pattern. The out-of-focusing of the projection optical system is set as the function of a deflecting amount and the position of the pattern in a one-shot exposed area and the energy profiles DR(x) and E(x) formed on the sensitive substrate, when exposure is made by using a primary reticle pattern are calculated. Then the threshold of developing energy is set, so that the edge position of each section of the pattern formed on a wafer correspondingly to the profile E(x) becomes close to a prescribed position. Thereafter, the line width of each section of the pattern at the threshold is calculated, and the primary reticle pattern is corrected so that the calculated line width coincides with the line width of the designed pattern. Successively, pattern data for writing a reticle pattern are prepared by performing shape correction and does correction. After writing the reticle pattern, a reticle is manufactured though development.

Proximity effect correction mask

Abstract: PROBLEM TO BE SOLVED: To provide a proximity effect correction mask which is capable of correcting an optical proximity effect without being affected by the space from a rectangular pattern on an adjacent mating side. SOLUTION: The four sides of the rectangular pattern 4 of the proximity effect correction mask for transferring the mask patterns consisting of the opaque rectangular pattern 2 and the transparent space pattern 3 are enclosed by the translucent phase shift 4. The width (W1

Method for correcting an optical proximity effect

Abstract: PURPOSE: To provide a method of correcting a light proximity effect so that the wiring width in the straight line part between the bending parts of a 'U shaped' pattern has a prescribed wiring width CONSTITUTION: This method for correcting the light proximity effect corrects the mask wiring pattern in order to compensate the light proximity effect when forming an etching mask by transferring the mask wiring pattern by photolithography The method described above includes a first step of extracting the 'U shaped' pattern of the design wiring pattern, a second step of providing the inner edges in the two bending parts of the 'U shaped' pattern of the mask wiring pattern with notch correction patterns according to a light proximity effect correction rule, a third step of calculating the spacing along the straight line part between the opposite ends of the notch correction pattern, a fourth step of comparing the spacing between the ends and a set spacing, and a fifth step of providing the bending parts again with the short notch correction pattern by shortening the length of the pattern portion along the straight line part of the notch correction pattern so that the spacing between the opposite ends of the notch correction pattern is to be a set spacing

Method of correcting light proximity effect

Abstract: PROBLEM TO BE SOLVED: To provide a method of correcting a light proximity effect so that the wiring width in the straight line part between the bending parts of a 'U shaped' pattern has a prescribed wiring width. SOLUTION: This method for correcting the light proximity effect corrects the mask wiring pattern in order to compensate the light proximity effect when forming an etching mask by transferring the mask wiring pattern by photolithography. The method described above includes a first step of extracting the 'U shaped' pattern of the design wiring pattern, a second step of providing the inner edges in the two bending parts of the 'U shaped' pattern of the mask wiring pattern with notch correction patterns according to a light proximity effect correction rule, a third step of calculating the spacing along the straight line part between the opposite ends of the notch correction pattern, a fourth step of comparing the spacing between the ends and a set spacing, and a fifth step of providing the bending parts again with the short notch correction pattern by shortening the length of the pattern portion along the straight line part of the notch correction pattern so that the spacing between the opposite ends of the notch correction pattern is to be a set spacing.

Trench pattern lithography for 0.13- and 0.10-μm logic devices at 248-nm and 193-nm wavelengths

Abstract: In this paper, logic device patterning of 0.16-micrometer trenches for the 0.13-micrometer node using 248-nm light and 0.13-micrometer trenches for the 0.10-micrometer node using 193-nm light is investigated. Severe proximity effect through all pitches and small depth of focus for isolated trenches bring great challenges. To produce manufacture-worthy process windows, lithographic techniques such as optical proximity correction, annular illumination, sub-resolution assist features, and attenuated phase-shift mask are considered. No prominent performance gain is achieved in the aforementioned combination if full-pitch-range performance is required. However, manufacture-worthy 0.5-micrometer depth of focus can be obtained through all pitches by replacing annular illumination with quadrupole illumination while retaining sub- resolution assist features and optical proximity correction, even without having to resort to attenuated phase-shifting mask. We also observe that attenuated phase-shift mask or dipole illumination improves depth of focus and photoresist profile of dense patterns only in the cases studied.

Electron beam exposure method, and mask and electron beam exposure system used for this

Abstract: PROBLEM TO BE SOLVED: To increase contrast, and resolution, and enlarge the margin of the quantity of exposure, by adjusting the quantity of auxiliary exposure, according to the density of patterns, in a scattering angle limitating system of an electron beam exposure method which performs the proximity effect correction by a ghost method at the same time with pattern exposure. SOLUTION: In a scattering angle limitating system of electron beam exposure method which controls the quantity of passed scattered electrons scattered by mask by means of a limiting aperture, using a mask having a scattering region, and performs the pattern exposure by the scattering contrast by the difference of the scattering angle of the electron beams having passed through the mask, the quantity of scattered electrons passing through the limiting aperture is adjusted by controlling the scattering angle of the scattered electrons, changing the thickness of the scattering region of the mask, according to the density of patterns, and the proximity effect compensation is performed at the same time with the pattern exposure by the auxiliary exposure of the scattered electrons having passed through the limiting aperture.

Investigation of OPC mask distortion effect

Abstract: Distortion effect in optical proximity corrected (OPC) masks on wafer level image has been investigated using combined simulation of photomask patterning process and projection optical lithography. Unlike the previous simulation of optical proximity effect, which were based on ideal mask design, the simulation presented in this paper is based on distorted mask features. The mask feature distortion comes from simulation of electron beam lithography or laser scanning lithography. Proximity effects in e-beam lithography or laser direct write has been taken into account for the generation of mask features. The simulation has demonstrated that the OPC compensation features are significantly distorted at mask level. Such distortions have noticeable impact on the wafer level resist images.

Aggressive optical proximity correction method

Abstract: A method of modifying a photo mask pattern by using computer aided design (CAD) is described. The photo mask pattern is used to manufacture a photo mask for transferal to a photoresist layer formed on a surface of a semiconductor wafer so as to form a predetermined original pattern. A first modification is first performed according to an optic proximity effect, and then a second modification is performed according to a line end shortening effect. The present invention prevents the line end shortening effect from occurring in a subsequent trim down etching process of the original pattern performed for reducing its critical dimension.

Electron beam lithography method and mask for electron beam lithography

Abstract: PROBLEM TO BE SOLVED: To provide an electron beam lithography method and a mask for electron beam lithography, with which a fine pattern can be written precisely by proximity effect correction and productivity can be improved. SOLUTION: A design pattern to be written is divided, depending on the area density distribution of a design pattern. By using a mask for electron beam lithography patterned for each divided region, each divided region is irradiated with a different irradiation dose of electron beam for correcting proximity effect. The design pattern to be written is divided, depending on the area density distribution of the design pattern, and the mask is patterned for each divided region.

Photomask and method for manufacturing semiconductor device using the same

Abstract: PROBLEM TO BE SOLVED: To provide a photomask suppressing the degradation of pattern fidelity due to the influence of a light proximity effect and to provide a method for manufacturing a semiconductor device using the photomask SOLUTION: In a photomask 100 used in a semiconductor manufacturing process, a first mask pattern 106 transferred to a resist pattern and a second mask pattern 108 of a resolution limit or less for suppressing the light proximity effect are provided The second mask pattern is made linear and a plurality of the first mask patterns are connected By turning the second mask pattern to a linear mask pattern, a parameter to be added to the simulation of the resist pattern can be reduced The photomask for efficiently performing the simulation and forming suitable resist is provided Also, the photomask can be used in the manufacturing process of the semiconductor device COPYRIGHT: (C)2003,JPO

New results in high-energy proximity x-ray lithography

Abstract: We report some new results in the use of high energy radiation in proximity x-ray lithography for the 50 nm node. The higher energy of the incoming radiation, 2.6-2.7 KeV, has two primary benefits: (1) it reduces the diffraction and allows printing of higher resolution features, and (2) it increases the effective depth of exposure allowing larger gap setting; however, the absorption of these photons creates hot electrons, which redistributes the energy in the resist, thus creating a uniform blur that limits the resolution by reducing contrast. The impact of the energy redistribution needs to be investigated when increasing the energy of the radiation, and in considering the materials used in both the optics and the mask and resist combination.

Resolution improvement of chemical-amplification resist using process-induced effect correction

Abstract: Resolution comparison of a CAR (positive resist) and ZEP- 7000 was investigated for 50 kV e-beam machine and dry etching process. The CAR is superior to ZEP-7000 in view of resist profile, while it is inferior in view of CD variation, after Cr dry etching. The etching results were improved using thin resist, optimizing the etching condition and process effect correction. The best performance was obtained form e-beam proximity correction. It is difficult to apply this model to a real device since it has model errors and inconvenience in data handling. Among the activities for the improvements, etch condition optimization is the most effective. A pattern fidelity issue such as edge roughness and line-end shortening remains even with a CD linearity improvement.

Method, device, and mask for correcting proximity effect and manufacture of device

Abstract: PROBLEM TO BE SOLVED: To provide a proximity effect correction method which can be used commonly for a lithography apparatus and a transfer device, able to use a negative resist, and prevent thermal deformation of a mask. SOLUTION: A method for correcting proximity effects is used for correcting proximity effects, which occurs at the formation of a pattern on a wafer 3 by electron beam exposure. In the method, a mask 1 which is divided into a plurality of sections having dimensions smaller than the spread dimension of back-scattered electrons at the making of an exposure pattern forming exposure and different reflectivity is prepared. The mask 1 is irradiated with a correction light, and reflected light from the mask 1 is projected upon the wafer 3. Since the reflection mask 1 is used as a mask for proximity effect correction, high-accuracy correction exposure can be performed reading, because the occurrence of the thermal deformations of the mask and the formation of a doughnut shape pattern in a stencil mask is prevented, as compared with the case where a transmissive mask is used.

Method for forming fine patterns and photomask

Abstract: PROBLEM TO BE SOLVED: To correct the irregular size of completed exposed images caused by the light proximity effect. SOLUTION: The exposure step subjected to a photoresist film is a multiple exposure step. The conditions of exposure of one exposure step comprising the multiple exposure step are set in such a way that the larger the distance between patterns, the more enlarged the exposed image is. The conditions of exposure of the other exposure step are set in such a way that the larger the distance between patterns, the more reduced the exposed image is.

Large-area electron beam radiation exposure dose determination for microelectronics layout, involves dividing the total surface area into several disjunctive part-areas with different structural widths

Abstract: A method ascertaining the radiation dose for a layout during surface/large-area electron beam exposure processing moves on from the short-comings of the so-called CFA (conditional figure assignment) method where the surroundings around the exposed figures are not included in the 'proximity' correction and only the separate free-standing exposure figures of the layout receive a sufficiently accurate correction of the proximity effect. The procedure now requires the total surface layout (S1) having several exposure figures with different structural widths and structure spacings to be divided into several disjunctive part-surfaces or areas Fx (x equals 1...n) which differ with regard to their structural widths and structure spacing and evaluation criteria Kx to be determined for the radiation dose on each of the separate part-surfaces or areas.

Method and system for drawing with electron beam

Abstract: PROBLEM TO BE SOLVED: To provide a method and a system arranging a thin-film electron source in a plural pieces in a matrix form, making an electron beam, having an arbitrary configuration irradiate by controlling the electron irradiation of the each electron emission parts, keeping minute workability, which the electron beam drawing has in an electron beam drawing system which projects image on a sample with a projection optical system, and trying to shorten the drawing time to improve the throughput. SOLUTION: The method and the system include reducing drawing time for satisfying the required drawing accuracy, by adjusting a drive voltage and drive time which spreading of a thin-film electronic source 1 depending on the required drawing accuracy revising the proximity effect by adjusting a drive time spreading, so that the energy piled in a pattern drawn becomes uniform simultaneously. The drawing time was reduced while keeping the required drawing accuracy. The proximity effect can be corrected efficiently.

Method for forming exposure mask of semiconductor device

Abstract: PURPOSE: A proximity effect can be reduced by weakening the intensity of light causing the lowering of the transmission rate and a high integration semiconductor device can be implemented CONSTITUTION: A step is to form a chromium pattern(15) on the upper portion of the quartz substrate(13) Thereafter, a step is to deposit a photoresist film on the whole surface upper including the chromium pattern(15) Then, a step is to form a photoresist pattern in order to make the quartz substrate(13) expose at the dense portion of the chromium pattern by exposure and develop it Next, a step is to form a process treatment portion(17) deteriorated the transmission rate by processing the quartz substrate by using a mask, the photoresist film layer Thereafter, a step is to remove the photoresist pattern The chromium is a pattern of shielding The process treatment process etches the quartz substrate to a depth from 5 to 100 angstrom

Proximity effect correction method, reticle, and method of manufacturing device

Abstract: PROBLEM TO BE SOLVED: To provide a proximity effect correction method which is capable of realizing a pattern of high dimensional accuracy. SOLUTION: Design patterns to be formed on a sensitive substrate are set. A pattern smaller than four times as large as the amount of fading of a charged particle beam used in a primary exposure process is extracted from the design patterns, and a pattern shape correction for correcting a proximity effect is calculated. Primary exposure reticle pattern data are formed in reference to the calculation result of the pattern shape correction. A primary exposure reticle for actual use is formed on the basis of the above pattern data. In this case, by the use of a variable forming beam-type electron beam drawing device, a dose adjustment or a shape correction or the like is carried out. Using this reticle, the sensitive substrate is subjected to a primary light exposure process by the use of a self-projection or split transfer-type electron beam projection exposure system.

A study of line edge roughness in chemically amplified resist for low energy electron-beam lithography

Abstract: We investigated the line edge roughness (LER) of the resist pattern in a high sensitivity resist process using low energy e-beam lithography (LEEBL). In order to explain the experimental results, we have proposed a model considering the secondary electron (SE) yield and the diffusion of SE. The results of simulation based on the proposed model indicated the following: (1) in the case of 2 keV, acceptable acid distribution is generated due to the high SE yield and the SE diffusion. As a result, a high quality resist pattern could be obtained, even if the exposure dose is below 0.5 /spl mu/C/cm/sup 2/, and (2) in the case of 50 keV, the acid generated at the unexposed area due to the proximity effect make the LER larger. Our simulation indicated that the LER of the 2 keV exposure with 0.4 /spl mu/C/cm/sup 2/ is smaller than that of the 50 keV exposure with 2 /spl mu/C/cm/sup 2/ 2. From these results, we think that high sensitivity resist process at the exposure dose below 0.5 /spl mu/C/cm/sup 2/ can be achieved in LEEBL.