Proximity effect (electron beam lithography)

About: Proximity effect (electron beam lithography) is a research topic. Over the lifetime, 940 publications have been published within this topic receiving 8508 citations.

Mask, and electron beam exposure method using the mask

Abstract: PROBLEM TO BE SOLVED: To enable application to the graphic batch plotting system of plotting a pattern for one chip with one shot, as well and to correct the influence of a proximity effect by providing a means for changing the number of electron beams passing through a mask substrate in accordance with the density of an opening pattern. SOLUTION: On a second mask 46, the opening pattern for one chip consisting of a large number of basic openings 40 is formed. At this time, the substrate of the second mask 46 is formed so that the thickness of the substrate is changed according to the density of the opening pattern to be largest in the central part of a mask and smaller as it goes to the end parts of the mask. Thus, the thickness of the mask substrate is changed according to the density of the opening pattern, to control the number of the electron beams passing through a nonopening part. The number of transmitted electron beams can be decreased in a mask part corresponding to the central part of an array where the opening pattern is dense and increased in the mask parts corresponding to the end parts of the array where the opening patterns are rough.

Resist Pattern Analysis For Submicron Feature Size Using 3-D Photolithography Simulator

Abstract: Photolithography has been used for manufacturing LSIs for a long time and it also becomes a key technology for submicrometer VLSIs. Three dimensional photolithography simulator, RESPROT, has been developed, and reported its concept and application data at the last SPIE's symposium, Vol : 922-02. In this paper RESPROT was improved to simulate optical aberrations, proximity effects and repeatable reticle defects which are remarkably important process factors on submicrometer pattern transfer. And resist pattern printability or fidelity were studied. At first three dimensional simulator, RESPROT, was improved for the quantitative calculation of higher order reduction lens aberrations and contrast enhance layer, CEL, for resist images. It was confirmed by the calculations that there is existent sixth order aberration and critical dimension loss was decreased by using of CEL. For proximity effect it is slightly improved by higher numerical aperture, NA, but resist images are deformed on defocusing. Printability of submicron reticle defects are depend on the defect type ; clear or dark defects. Both defects decrease imaged resist sizes on defocusing, but these are transferred more clearly on higher NA imaging. Also reticle defects are printed with more faithful by optical aberrations.

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.

Beam profile measurement method and exposing method

Abstract: PROBLEM TO BE SOLVED: To provide a method for measuring a beam profile for analyzing acid diffusion within a resist, flare, and aberration in an optical system, and to provide an exposing method for accurately correcting proximity effect SOLUTION: The beam measurement method comprises a process for exposing a plurality patterns onto an exposure surface with a specific interval for measuring the line width of a specific pattern, a process for performing exposure and measuring the line width by changing the pattern interval, a process for calculating the forward scattering and backward scattering in the exposure surface by simulation, a process for obtaining the aberration of an optical system by fitting a simulation result to a measurement result with the aberration of the optical system as a variable, a process for obtaining flares from the deviation between the measurement result and the simulation result, and a process for obtaining acid diffusion by changing process temperature The exposure method is used to correct the proximity effect, based on the beam provide measurement method

High-dose exposure of silicon in electron beam lithography

Abstract: Nowadays, features with sizes smaller than 10 nm can be obtained with electron beam lithography. For such small structures, high exposure doses are required to stay away from the shot noise limit. We investigated the effect of high-dose electron exposure of silicon substrates and subsequent dry development by reactive ion etching. We found that silicon can be directly patterned at electron doses ranging from 0.05 to 3.06 C/cm2. The effect of backscattered electrons is seen as a halo around the patterns. In the given dose range, a gradual transition from positive tone low-dose to negative tone high-dose behavior is observed. It is demonstrated that the patterning is likely to be caused by structural changes of the silicon substrate, resulting in different etch rates in exposed and unexposed areas. X-ray photoelectron spectroscopy analysis has been applied to determine if the thickness of the native oxide in the irradiated areas is different from the thickness at a reference position not irradiated. Small but significant differences have been observed, the largest increase being 0.3 nm.