Showing papers on "Proximity effect (electron beam lithography) published in 1980"

Proximity effects in electron lithography: magnitude and correction techniques

Abstract: Proximity effects due to electron scattering in the resist and substrate seem to set a fundamental limit to the areal density that can be achieved in electron lithography. This work briefly reviews the form and the magnitude of the proximity function and its extent as evidenced by deviations in designed linewidths. It also discusses methods to decrease the proximity effect as well as the algorithms used for correction of such effects.

Electron beam exposing device

Abstract: PURPOSE:To simplify the correction of proximity effect by a method wherein, pertaining to each exposure pattern grown in rectangularly divided form, the irradiation dose and the amount of measurement correction, with which desired exposure pattern can be obtained, are calculated and a measurement correction is performed in such a manner that the pattern shape after exposure will not be changed CONSTITUTION:At the sample point SO1, the formula Q1F(r1)+Q2F(r2)+Q3F(r3)+ Q4F(r4)=E is formed At this point, Q1-Q4 are the irradiation doses of exposure patterns 1-4, and F(r1) (i=1-4) is the strength of exposure of patterns 1-4 Also, the exposure strength F(r2) of the exposure pattern 2 is indicated by the formula F(r2)= integral integral f(r)dS As the exposure pattern 2 is a submicron pattern and it is substantially effected by an exposure pattern 3, the exposure pattern 2 is eliminated when the measurement correction amount l of the exposure pattern 2 exceeds pattern length H, new splitting lines are provided as shown by the broken line in the diagram for the exposure pattern 1 which comes in contact with the eliminated exposure pattern 2, and an exposure pattern 1A is provided As for the splitted exposure patterns 1 and 1A, they are corrected by having a correction amount for each of them Through these procedures, the correction amount for the measurements and the irradiation dose of the electron beam are determined when the pattern data is prepared

Proximity correction enhancements for 1-µm dense circuits

Abstract: The proximity effect in electron-beam lithography, which is due to electron scattering in the resist and wafer, results in nonuniform exposure and development for patterns in which the incident doses of all the shapes are the same. Correction for this effect has been accomplished in the past primarily by varying the incident doses of all the shapes in order to achieve an equal average resultant dose per unit area for all shapes. We show that in the case of dense circuits with linewidths of about 1 µm or smaller, two enhancements to the proximity correction technique can be easily implemented. One of these is a simple approach to shape breakup (partitioning) to enable dose correction to be applied nonuniformly within the original design shapes. The other technique is a new type of algorithm for forming subsets of the design to perform self-consistent dose correction. These two enhancements are applied to LSI chip data for dense circuits and are shown to permit fabrication of circuits which would be more difficult to process using the proximity correction techniques described previously, due to the particular geometries present in these circuit designs. We also show the application of step and repeat pattern recognition algorithms to compact the resulting data, and consequently to reduce the amount of data by an amount which is greater than the increase in the number of shapes caused by partitioning.

Process for compensating the proximity effect in electron beam projection devices

Abstract: Zur Kompensation der Streuverluste von Elektronen in Photolacken (Proximity Effekt), die sich bei der Elektronenstrahllithographie durch Anderungen der Mustergeometrie auswirken, wird vorgeschlagen, ausgewahlten Teilgebieten (22,23,24) eines Musters eine zusatzliche Bestrahlungsdosis in einem zweiten Belichtungsschritt zuzufuhren. To compensate for the wastage of electrons in photoresists (proximity effect), which have an impact by changes in the pattern geometry in electron beam lithography, it is proposed to selected fields (22,23,24) of a pattern supplying an additional radiation dose in a second exposure step. Dazu kann eine besondere Maske mit entsprechenden Korrekturoffnungen dienen, die mit gleicher oder anderer Elektronenstrahlintensitat beaufschlagt wird. For this purpose, a special mask with corrective openings are to be subjected to the same or different electron beam intensity. In besonders vorteilhafter Weise last sich die Korrektur des Proximity Effekts bei Verwendung von Komplementarmasken erreichen: Dazu werden die Korrekturoffnungen (z. B. 50b, d) fur die Teilgebiete (40b, d) der einen Komplementarmaske (42) in der anderen Komplementarmaske (41) angeordnet. In a particularly advantageous manner, the correction of the proximity effect when using complementary masks can be achieved: given the correction openings (eg 50b, d.) For the sub-regions (40b, d) of a complementary mask (42) in the other complementary mask (41 ) arranged. Die Korrektur des Proximity Effekts erfolgt dann ohne zusatzlichen Belichtungsschritt. The correction of the proximity effect is carried out without additional exposure step. Zur Messung des Proximity Effekts wird ein lichtoptisches Verfahren vorgeschlagen, bei dem Strichmuster mit abnehmender Stegbreite im Photolack durch Elektronenstrahl p rojek- tion definiert werden und der Entwicklungsprozes des Photolacks vorzeitig abgebrochen wird. To measure the proximity effect, a light-optical method is proposed to be defined in the dash pattern with decreasing land width in the photoresist by electron p rojek- tion and the development process of the photoresist is prematurely terminated. Die bei Vorliegen des Proximity Effekts unsymmetrischen Stegkanten lassen sich dann leicht im Mikroskop feststellen. The unbalanced in the presence of the proximity effect web edges can then be easily determined in the microscope.

Dependence of pattern dimensions on proximity functions in electron beam lithography

Abstract: The departure from the prescribed dimensions for simple patterns have been calculated as a function of proximity function parameters. Seven sets of proximity function parameters are used in this work. Using these, an attempt is made to delineate the effect of each parameter on variations in pattern dimensions. With parameters appropriate for high incident electron kinetic energies, it is shown that with increasing energy, even though the backward‐scattered distribution increases, the proximity effect seems to decrease. Also, effects due to proximity function parameters appropriate to high‐Z substrates are also investigated.

Quantitative evaluation of proximity effect in raster-scan exposure system for electron-beam lithography

Abstract: The proximity effect in a raster-scan for electron-beam lithography system was evaluated by Monte Carlo calculation and verified by experiments. It was revealed that the reduction in the beam diameter below the scanning pitch, which links into the shortening of drawing time, is more effective in decreasing the proximity effect than the reduction in the resist thickness. From the calculated results, it was found that the error in linewidth definition due to the proximity effect was less than 10 percent at a linewidth of 1.5 µm with scanning pitch of 0.5 µm, beam diameter of 0.2 µm, and PMMA resist of 1.0-µm thickness.

Pattern partitioning for enhanced proximity-effect corrections in electron-beam lithography

Abstract: This paper presents new algorithms for judicious partitioning (or subdivision) of arbitrary lithographic patterns in order to achieve increased quality of proximity-effect correction as well as increased efficiency in the computation of such corrections. Experimental results verifying the correctness of such algorithms are also presented.

Electron beam line drawing device

Abstract: PURPOSE:To get just enough quantity of exposure and to avoid proximity effect, by dividing figure in plurality and changing scanning speed in every each figure, on electron beam equipment which draws minute pattern on electron sensitive resin film with electron beam. CONSTITUTION:Speed signal is inputted into scanning signal generating circuit 14 by signal line 16 which is designated the plural number of scanning speeds from calculating machine 12. Signal from counting machine 12 which designates figure via figure generating circuit 15 and D/A converting circuit 14 and selects scanning speed, is inputted into scanning signal generating circuit 14 and let make scanning of beam by deflecting circuit 5 subject to scanning speed which is responding to its figures. Beam is scanned from electron gun 1 to to-be-processed test material 3, which is set on testing material moving stand 4, via interrupting circuit 8 and deflecting circuit 5 and draws minute pattern.

Pattern exposing method

Abstract: PURPOSE:When light is irradiated on an electron beam resist to form a pattern, to combine electron beam exposure with far ultraviolet ray exposure thereby to remove influences due to proximity effect and to evade the lowering of the pattern precision. CONSTITUTION:The far ultraviolet ray radiation and electron beam radiation in the photosensitive wave length range of an electron beam resist are combined with each other, and the resist film is doubly subjected to exposure treatment. Now, when an electron beam of a specific width a is radiated on the electron beam resisting film 1, the lower part of the film 1 comes to have a width b widened by the back scattering within the film 1. Accordingly, at a place where patterns approach the patterns assume a connected state by the proximity effect. As a result, after parts of patterns 2, 3 and 5 are exposed by electron beams, only the part of the pattern 4 is subjected to far ultraviolet ray exposure by use of a mark exposing only the part of the pattern 4 and exposed doubly to prevent influences due to the proximity effect.

Quantitative Evaluation of Proximity Effect in Raster-Scan Exposure System for Electron-Beam Lithography

Abstract: The proximity effect in a raster-scan for electron-beam lithography system was evaluated by Monte Carlo calculation and verified by experiments. It was revealed that the reduction in the beam diameter below the scanning pitch, which links into the shortening of drawing time, is more effective in decreasing the proximity effect than the reduction in the resist thickness. From the calculated results, it was found that the error in Iinewidth definition due to the proximity effect was less than 10 percent at a linewidth of 1.5/spl mu/ m with scanning pitch of 0.5 /spl mu/m, beam diameter of 0.2 /spl mu/m, and PMMA resist of 1.0-/spl mu/m thickness.

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.

Consideration on fine‐patterning techniques in eb lithography

Abstract: The corrections on the beam distortion and proximity effect in the electron-beam lithography are discussed from the viewpoint of computer processing. The coefficient parameters of the beam-deflection-distortion mapping function are estimated by the least square method from the measurement data of the beam deflection distortion, and the error distribution is clarified. The measurement errors in the movement and rotation of the sample desk are minimized. For the proximity effect correction at the rectangular beam illumination, the illumination intensity distribution function is approximated to the trapezoidal form and the computer simulation is made for the calculation of the exposure dose. Finally, the dependences of the beam scanning direction and the scanning interval on the proximity effect are examined by computer simulation.