DD151231A1 - OPTICAL ARRANGEMENT FOR PROJECTION SLITHOGRAPHIC EQUIPMENT - Google Patents

Abstract

Optical arrangement for projection lithographic devices with only one light source, a selecting optical element, a condenser, a template, optical beam splitters in the vicinity of the template. The optical arrangement is used in the manufacture of semiconductor devices, for transferring stencil structures to substrates. It is designed to help increase the level of automation, accuracy and productivity of projection lithographic equipment. It is the object of the invention to design the optical arrangement to transmit a large amount of light of the adjustment and exposure wavelength while allowing adjustment and exposure of a chip or a group of chips. For this purpose, the selecting optical element is designed as a movable reflector with at least two different regions. The beam splitters are associated with selecting optical means that constantly turn off the actinic light.

Description

Titgl; Optical arrangement for projection lithographic devices

Field of application of the invention

The invention relates to an optical arrangement for projection lithographic devices which contains a light source and in the beam path emanating from the light source at least one selecting optical element, a condenser, a template, a projection objective and a substrate. In the vicinity of the template, optical beam splitters and downstream photoelectric microscopes are provided for parts of the beam path. The selecting optical member can take at least two switching positions and can be in all switch positions anactic light and at least one of the switching positions only actinic light pass. The invention is used in the manufacture of semiconductor devices for transferring template structures to substrates. Devices of the step-wise Pr о jktions1ithogra fie serve this purpose.

Characteristic of the known technical solution:

Devices of the stepwise projection lithcgrai with visual overjet setting are already known, with the same projection system being used for the illumination of the template and the substrate, and a visual examination system for a tsetil of this projection beam path vcr-ѵѵэпсзь. In the case of the overburdening of exposure, the dos о о в тс. г- о '· "JV'""" 1 hl- lsI ^ ^{5v Ύ} o ^A ^ * '"c- ^ uq vinuslj Q Ϊ. · ί1 kroskoo and with in-: r. -!. :: inae :; t a fil the dos projectionobjective: tivs as well

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a filter is removed from the beam path and exchanged against matched to the exposure wavelengths and the exposure beam path similar optical components. The visual coverage is too slow and inaccurate for making very accurate circuits with exceptionally small bar widths.

A semiautomatic overlapping repeater is also known in which two illumination beam paths with fixed filters emanate from a light source. The alignment marks of the template and the substrate, which are imprinted with projection lenses, are automatically aligned with each other after each step. Progressive projection photolithographic devices are increasingly used for integrated circuit fabrication. At the same time, the demands on the adaptability of these devices with regard to the different chip sizes and structural dimensions are increasing. The previously required fixed or only slightly variable device-bound Justiermarkenlage leads to limitations for circuit arrangements and to increase the chips. For the most effective use of the substrates and chips, it is necessary to arrange the alignment mark associated with each chip or each chip group for the location (x-y position) and the angle (f) inside or outside the chip on the chip edge. These higher requirements must be met in particular the coverage system.

Aim of the Invention: c:

The invention is intended to eliminate the disadvantages and to increase the degree of automation, accuracy and labor productivity.

Parleyung of the invention:

The invention has for its object to provide an optical arrangement for a Überdeckungsrepeater that allows to transmit a large amount of light of the adjustment and exposure wavelengths and, on the same side, the adjustment and. Exposure enables a chip or group of chips.

According to the invention, the problem is solved in that the selecting optical element is provided as a movable directional actuator

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at least two different areas is formed, and that the beam lector selection optical means are assigned to turn off the actinic light constantly. It is advantageous for adjustment purposes, the optical radiation. Lenteiler parallel to the template to arrange displaceable. The reflector may be vortsilhafterweise formed as a sector disk.

Dielectric layers, on which the light is reflected, are used to select the required longitudinal areas. This results in comparison to the use of absorption filters a much higher light output and a shortening of the times for exposing and adjusting and for short-term adjustments a fast Meßsignalgewinnung. By means of the invention it is possible to use one and the same illumination system for the exposure, the coverage and the adjustment. This is also achieved that with optimal adjustment of the lighting system to the imaging system for Strukturübeztragung automatically the lighting system is optimally adapted to the imaging system of the automatic adjustment. The sector mirror only ensured the coverage mask and substrate and won. then the transmission of the structure (exposure). In this case, the light of the calibration wavelengths is reflected in all positions and the light of the exposure wavelengths in one position. Thus, it is also possible to keep the Jberdeckungszustand regulated during the exposure and thus exclude a displacement of the template and the chip on each other during the exposure. This is particularly important in the transmission of fine structure, and keeping the xoherence parameters constant is particularly ensured if, by varying the size of the aperture of a projection objective and replacing parts of the condenser system, the resolution can be varied as a function of field size With a higher aperture, in addition to the higher element resolution, a higher resolution of the alignment mark images is automatically realized, so that a better coverage accuracy is achieved during the transmission of fine structures, which is obtained during exposure The ceiling of the structures lies in the eldmixte and is usually rectangular

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optical arrangement of circular fields are illuminated and displayed, stands for the Justiermarken in the peripheral circle segments still a relatively large field for .Verfügung. In order to keep the unused area of the chip as small as possible, the alignment marks and their surroundings must also remain as small as possible; The position of the alignment marks can be varied over a relatively large field. For this reason, the beam path of a first AbbiIdungsstufe the automatic adjustment by moving optical elements, equipped with selecting optical means in the x and y direction within the unused for structure transfer left or right segment of the field to be imaged changed so that the alignment marks on Places of neighboring structure fields come to lie, which are unused, z, B. am.Chipfeldrand or in Rit2Tgraben. These optical elements are beam splitters for illuminating and imaging the alignment marks and compensation means such as double mirrors or rhomboid prisms to compensate for the chromatic longitudinal deviation of the reflection objective for adjustment to exposure wavelengths. Beam splitters and compensation means can be advantageously combined in an optical component.

At the time of writing:

The invention will be explained in more detail below with reference to the schematic drawing. Ss show:

Fig. 1 shows an optical arrangement according to the invention and

1 shows a lighting system 1 to 5 for exposure and adjustment, an imaging system 6, 9, 10 for the exposure and an imaging system 6 to 11 for the adjustment.

The illumination system consists of the image 1 (secondary light source) generated by a light source, not shown, preferably a high-pressure mercury lamp, an intermediate imaging optics 2 with lenses 2.1, 2.2, 2.3 »2.4, a selective mirror p, a reflector disc 4.1 offset by a motor in rotations Condenser system 5 with lenses 5.1., 5.2, a V / Abankondensor 5.3 and a Y / echselcptik 5 «4 with a lens 5 · 4 · 1 and a Ield.linse 5 · 4«. 2 To-.L. Educational System:.! ....:

for the exposure, the structures 6.3 include a template 6, a projection objective 9 and the photoresist-coated surface of a substrate 10. The imaging system for the adjustment, in place and inverse is formed by alignment marks 6.1 and 6.2, beam splitter mirrors 7.1 and 7.2, selective mirrors 8.1 and 8.2, a projection lens 9 and. Alignment marks 10.1. and 10.2 on the substrate 10. The mirrors 7.1 and 7 · 2 are covered with dielectric layers which allow a 1: 1 beam splitting of the anactic light and greatly reduce the reflection of the electric light. The selective mirrors 8.1 and 8.2 carry dielectric coatings which to a large extent reflect the anactinic light and prevent the reflection of the actinic light.

Fig. 2 shows the reflector disk 4 x 1 of the selective "closure" consisting of four sectors, 4 x 1.1 to 4.1.4, of which two are always diametrically opposite, the two sectors 4 "1 x 1 · And 4.1 · 2 are covered with dielectric layers that reflect only anactic light, and the two sectors 4.1.3 and 4.1.4 carry dielectric coatings that reflect both actinic and anactinic light.

The image of Lichtquellenbilde3 1 on the reflector disc is marked with 4 * 1.0.

The light emitted by the light source image 1 and freed from its red and infrared components is guided in the illumination system via the fixed selective mirror 3. The mirror layers only reflect light of the exposure time length (actinic light) and light of the adjustment wavelength (anactic light), so that after intermediate imaging with the aid of the lens system 2 on the reflector disk 4.1, the light source image 4.1.0 arises in the selected V / all-length ranges. If the sector 4.1.1 of the reflector disk 4.1 is in the beam path, then only the anactic light is reflected and guided via the condenser system 5 to the template 6 for uniform illumination of the alignment marks 6.1 and 6.2, but also of the structures 6.3. In the imaging beam path for Justieruiig now takes place the exact mapping der'Justiermarken 6.1 and 6.2 using the otrahlentsilGrspiegel 7.1 and 7 · 2, the Seiektivspiegel 8.1 and 8.2 and the Pi ojektionsobj ektivs 9 on the Just-τ

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mark 10.1 and 10.2 of the substrate 10, the common demotion of the Justiermarkeri 10.1 and 10.2 and the images of the alignment marks 6.1 and 6.2 via projection lens 9, selective mirror 8.1 and 8.2, through the beam splitter mirror 7.1 and 7.2 into a conjugate plane and the other Figure -in unspecified photoelectric LIi-. Kroskopen Tl .1 and 11.2.

The structures 6.3 of the template 6 are imaged very blurred with the projection lens 9 on the surface of the substrate 10. This process with anactinic light does not result in the exposure of the photoresist.

Is the overlap of Justierinarken 6.1 and 6.2 to the Justiermarken 10.1 and 10.2 by displacement of template 6 and substrate 10 to each other in place (translation χ and y) and angle (rotation φ) by means of controlled adjusting systems 13 · 1 and 13.2 through the photoelectric microscopes 11.1 and 11.2 is reached, for the purpose of exposure, the reflector disk 4 · 1 by the motor 4, for example stepper motor, rotated by 90 °, so that now the sector is 4 · 1 · 2 in the beam path and actinic and anactinic light is reflected. In this case, it is advantageous that the reflector disk 4 * 1 is in a plane conjugate to the aperture 9.1 of the projection lens, so that no high demands are made on the uniformity of the reflection over the surface 4 * 1.0 and on the uniformity of the rotation of the reflection disk 4.1 open and close the selective closure 4 werd.en need. The actinic light is passed over and anactinic d _a s condenser 5 for the uniform illumination of the structures 6,3 'but also the alignment marks 6.1 and 6.2 on the template. 6 With the actinic light, the structures 6,3 are projected by the projection lens 9 sharply on the photoresist coated surface of the substrate and so de exposure carried out, while the very blurred image with anactinic light without influence on the exposure remains. On the same side takes place in the imaging beam path for the adjustment, the sharp image of Justiermarken 6.1 and 6.2 of the template 6 on Justierraarken 10.1 and 10.2 on the substrate 10 with anaktinischem light and as described above, the Rüclcabbiidung in a conjugate plane and the further figure in cU.u iotoelektririschen Li-microscope 11.1 and 11.2. The actinic light is in the imaging beam path

for the adjustment by suppression of Refelxion at the dielectric layers of the beam splitter mirror 7.1 and and. the selective mirrors 8.1 and 8.2 are eliminated in order to eliminate such effects as the additional, very blurred image of the alignment marks with actinic light or the exposure of the alignment marks 10.1 and 10.2 on the substrate 10. The exposure process is completed in accordance with an automatic exposure 12, by the reflector disc is rotated ura 90 more, so that the sector is 4 · 1.3 in the beam path and only anactic light is used for illumination.

Instead of being a rotatable disk, the reflector 4.1 can also be designed as a rectangular plate which can be transversely displaced relative to the beam path and has actinic and anactinic regions.

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Claims (3)

cn stir u с h: An optical arrangement for projection lithographic apparatus comprising a light source and in the beam path emanating from the light source at least one selecting optical element, a condenser, a template, a projection lens and a substrate, in which the optical beam splitter and downstream photoelectric Microscopes for T _e ils the Strohlengange * are provided and where the selecting optical tO member occupies two switching positions, which in both switching positions and Ьеіщ switching let anactic light and in one of the two switching positions alrtinisches light, characterized in that the selecting optical member is designed as a movable reflector with at least two different areas and that the beam splitter selecting optical Means are assigned to turn off the actinischa light constantly . 2> Optical arrangement according to item 1, characterized in that the reflector is designed as a rotatable sector yoke. 3. Optical arrangement according to item 1, characterized in that the optical beam splitters are arranged to be displaceable substantially parallel to the template. For this 1 page drawings