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.

Electron-beam exposure method

Abstract: PURPOSE:To reduce a proximity effect through simple operation, and to obtain a pattern of a fine shape with high accuracy by drawing electron beams in the quantity of a dose lower than the aimed quantity of a dose on a resist film in a repeated manner when electron beams are drawn on the resist film and the film is exposed CONSTITUTION:Polymethyl methacrylate is rotary-applied onto a blank mask or a wafer, and baked to form the positive type resist film Electron beams are irradiated to the film and drawn, but they are drawn first in the half quantity of a dose of the aimed quantity of a dose at that time Electron beams are irradiated to the same section in the half quantity of a dose again, and the section is developed and treated to form the resist pattern Accordingly, a section subject to the proximity effect is difficult to be developed, and the pattern is fined Electron beams may be drawn twice while halving irradiation time in place of twice irradiation while halving the quantity of a dose

Analysis of pattern accuracy in submicrometer electron-beam direct writing

Abstract: To create submicrometer patterns with high accuracy on thick single-layer negative resist, error factors that degrade pattern accuracy have been investigated. Pattern accuracy was analyzed using a new evaluation method based on the difference between the resist development energy and the exposure energy at points on the edge of each shape. By introducing a new evaluation parameter, we were able to clarify error factors from the exposure conditions, the proximity effect correction method, and the machine exposure fluctuation. The evaluation parameter K is Q/Q_{0} where Q is the exposure dose appropriate for the desired resist thickness and Q 0 is the interface gel dose. It was found that the resist resolution and the rounding error of the exposure dose were serious error factors, especially in delineation on submicrometer patterns. To achieve 0.5-µm patterns with ±0.1-µm accuracy on 1-µm-thick negative resist, the resist evaluation parameter K must be less than 2, the rounding error of the exposure dose must be less than 2.5 percent of the dose, and the beam addressing unit (LSB) must be less than 0.025 µm.

Method and program for correcting and testing mask pattern for optical proximity effect

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.

Projection aligning method

Abstract: PROBLEM TO BE SOLVED: To provide a projection aligning method which can perform, transfer and expose with higher resolution than normal resolution and can reduce the thinning of line widths even when no special reticle is used SOLUTION: In a projection aligning method, a mask pattern 3 is formed by an electron beam lithography method The mask pattern is transfer-exposed onto a wafer 6 in a state where such a phase shifter 7 that causes a phase difference of light between an optical axis-side central part and its peripheral section is interposed near a pupil 5 of a projection optical system The thickening of the mask pattern caused by the proximity effect of an electron beam when the mask pattern is drawn with the electron beam is compensated by the thinning of the pattern transferred onto a sample caused by the proximity effect of the light projected upon the sample for forming an image on the sample through the phase shifter 7

Fine and coarse patterns mfr. on substrates - by computer controlled electron gun using beam with constant raster frequency, esp. during mfr. of microelectronic devices

Abstract: The fine and coarse patterns are adjacent to each other, and are made by an electron gun producing a beam with constant raster frequency, which is pref. within the range 200 kHz. to 40 MHz. The voltage on the Wehnelt cylinder in the gun is varied according to the size and density of the different patterns, the variation pref. being ca. plus-or-minus 10% from the operating Wehnelt voltage. The substrate is pref. a semiconductor wafer made of Si, Ge, Se-Te-B crystals, or a 3-5 cpd.; a ferrite wafer; a garnet wafer; or a glass plate coated with Cr, chromium oxide, iron oxide or >=2 of these substances. The invention avoids the proximity effect when making patterns of ca. 1 mu m next to structures of 20 x 100 mu m. A semiconductor substrate, or a coated glass plate required as a mask, is coated with a PMMA lacquer, which is exposed to the electron beam to break down some lacquer mols. removed by a developer to leave exposed patterns on the substrate.