EP1493060A2

EP1493060A2 - Method and device for imaging a mask onto a substrate

Info

Publication number: EP1493060A2
Application number: EP03725009A
Authority: EP
Inventors: Roland Kaplan; Jürgen SOLLNER
Original assignee: Heidelberg Instruments Mikrotechnik GmbH
Current assignee: Heidelberg Instruments Mikrotechnik GmbH
Priority date: 2002-04-11
Filing date: 2003-04-11
Publication date: 2005-01-05
Also published as: US20050122495A1; AU2003227607A1; WO2003085456A2; CN1659478A; JP2005527848A; DE10317050A1; CA2482155A1; WO2003085456A3

Abstract

The invention relates to a method for imaging a mask (1) onto a substrate (2) by means of an illuminating unit (8) and an optical unit (9). The invention also relates to a device for carrying out the method. The aim of the invention is to create a method and a device which enable the mask (1) and the smaller structures thereof to be imaged onto the substrate (2) in a precise manner, with high functional reliability, and which enable the distortions of the substrate (2) to be corrected. To this end, the illuminating unit (8) and the optical unit (9) are displaced in relation to the mask (1) and the substrate (2), distortions of the substrate (2) are detected, and the imaging of the mask (1) is distorted according to the detected distortions by means of the optical unit (9) and is adapted to the distortions of the substrate (2).

Description

Method and device for imaging a mask on a substrate

The invention relates to a method for imaging a mask on a substrate according to the features specified in the preamble of claim 1. The invention further relates to an apparatus for performing the method.

Such a method and a device for carrying it out are known from DE 39 10 048 C2. This is an alignment system in photolithography with which a mask, a large-area substrate and a transmission system, which contains an illumination unit and an optical unit, can be aligned relative to one another, structures from the mask being transferable to the substrate in small areas , When transferring or imaging the structure of the mask onto the substrate, a marking is applied to it, and when the structures of the mask are scanned, the mask is continuously aligned with respect to the substrate in relation to the respective region. The mutual alignment of the mask and the substrate requires a certain amount of equipment, and especially due to time delays and inertia of the alignment system, there are limits to the transmission speed and the achievable throughput.

BESTATIGUNGSKOPIE In the following, a template is referred to as a mask, which is used for the production of, for example, printed circuit boards or flat screens and is designed as a film, emulsion mask, chrome mask or the like. Such masks contain small structures, such as, for example, conductor tracks or generally geometric structures, which are to be imaged or copied onto a substrate. The typical size of such structures depends on the respective application and is today, for example, 10 to 50 μm in printed circuit board technology. Structure sizes down to 1 to 2 μm can be expected in the production of flat screens. The tolerance in the placement of the structures and their positional accuracy is significantly smaller than the structure sizes themselves. Flat, plate-shaped production elements or production benefits are referred to as substrates. For example, the production of printed circuit boards requires the multiple copying of various structures onto pre-products, intermediate products and the end product, which forms the carrier board for the electronic components and the required electrical connections. The size of printed circuit boards today is in the order of up to 600 x 800 mm ² , and due to the aforementioned preliminary, intermediate and end products, there is talk of multiple benefits. Very similar process steps also occur in the production of flat screens, whereby significantly smaller dimensions have to be taken into account for the structure sizes and tolerance limits. The following table summarizes typical applications or substrates, which are also called benefits or useful elements below:

1. Printed circuit boards: structuring of the copper surfaces, structuring of flexible printed circuit boards, networking of the solder resist or positive varnish.

2. Screen technology: paint image for structuring metallic or non-conductive layers, networking the color filter, creating structures on flexible substrates, such as B. slide screens.

3. Microstructure technology: creation of working copies, direct exposure of large flat workpieces, such as B. photovoltaic elements.

Flat, flat substrates are usually quite thin and have a thickness of a few μm (micrometers) to many mm (millimeters) and are coated with a light-sensitive layer that has to be structured. Go through the useful elements Different production steps, where high temperature differences and other mechanical stresses can occur. Such stresses can lead to permanent geometric changes. For example, printed circuit boards are composed of several layers of carrier foils, and this process is often referred to as pressing. The intermediate products that are assembled or pressed in this way have dimensional deviations which must be taken into account in the next production step so that, for example, fine conductor tracks can be covered with equally small vias. Accordingly, the individual picture elements are to be contacted in the production of screens.

The distortions of the useful elements occurring in the production process fundamentally limit the structures that can be produced in a minimally sensible manner. So that the desired functions can be realized by means of the structures of different layers or useful elements, a minimal overlap must be guaranteed. For this it is necessary that with a minimum structure size Z and taking into account a manufacturing tolerance dZ the associated counter structure has the size Z + 2 x dZ. This ensures that the structures overlap in the event of a position error dZ. If, on the other hand, the deviation between the structure or the mask and the useful element is too large, the structures assigned to one another no longer overlap. Furthermore, the problems inherent in optical imaging must be taken into account, namely the positional accuracy and the sharpness of the image. This means that the image of the template or mask must be imaged as precisely as possible on the structure or the use and the focal plane of the image must be on the light-sensitive layer of the substrate.

Proceeding from this, the object of the invention is, on the one hand, to design the method and, on the other hand, the device in such a way that, taking into account the relationships shown above, the templates or masks and their small structures on the substrate or the useful element are achieved with a high degree of functional reliability becomes. The creation of precise copies of small structures on preferably large substrates and / or useful elements should be possible without problems. Structures of the mask that are as small as possible are to be imaged and / or generated on the substrate with high positional accuracy. Furthermore, the The method and the device can be used economically and enable a high throughput.

This object is achieved with regard to the method according to the features specified in claim 1. With regard to the device, the object is achieved according to the features specified in claim 9.

The proposed method and the device proposed for carrying out the same, with high functional reliability and with comparatively little effort, enable the creation of precise copies of small structures on in particular large substrates or the production of small structures on a distorted substrate with high positioning accuracy. According to the invention, the mask, which represents the original in the nominal dimensions, is corrected and / or distorted in the imaging by means of the optical unit or in the copying process, and thus the image of the mask on the substrate or the useful element is adapted to its individual distortions. Thus, even the smallest structures with high positioning accuracy are generated on the distorted substrate, this process being referred to below as distorting the mask image.

According to the invention, the image of the mask can be individually distorted in each direction and thus corrected and in particular scaled such that distortions of the substrate are compensated for. According to the invention, the height and width of the mask image or its dimensions in the X-plane and the Y-plane of the substrate are adapted to any distortions. Furthermore, compensation of higher orders can be carried out in a preferred manner, the width of the image being a function of the height thereof or vice versa. In particular, a rectangular template or mask is transformed into a parallelogram or, more generally, into a trapezoid in accordance with the determined distortions of the substrate. According to the invention, the proposed distortion and / or transformation is determined individually for each benefit element and / or for each partial area of the same or of the substrate. The correction and / or transformation parameters determined in particular according to the distortions of the substrate serve to correct the mask image during the imaging or during the copying process. According to the invention, the mask image is distorted and / or aligned by overlapping and / or continuously joining individual images, each of which is smaller than the total Illustration. The distortions are carried out in the context of the invention in particular by translation and / or rotation and / or shear and / or direction-dependent scaling. The method and / or the device are neither restricted to specific structure sizes, nor are tolerance limits due to the method to be observed. There are also no limits to the size or dimensions of the substrate.

So that the image of the mask or template is mapped as precisely as possible on the substrate or panel and an exact alignment is achieved, both the mask and the substrate preferably have mechanical devices or markings. In the simplest case, reference bores can be provided for this purpose, by means of which the position of the mask and of the useful element are individually fixed by means of pins. In the case of very thin useful elements and the large distortions that occur here, this is not expedient since the substrate could curl. In the case of very thin useful elements, markings are therefore applied, for example fiduchals or alignment marks or Alinement markings, which are evaluated via an associated optics and a camera system. By measuring such markings, information about the position of the mask and / or the position of the useful element is determined. The corresponding measured values are used to calculate the distortion, e.g. the displacement or rotation of the useful element. In the method according to the invention and the device proposed for carrying out the same, simple optical components are used, and according to the invention the mask image is distorted and, taking into account the detected distortions of the useful element, mapped to the required correct position of the useful element. Furthermore, according to the invention, in order to maintain an optimal image, in particular with the correct structure size, edge quality and edge steepness on the useful element, the focal plane of the image is imaged on the light-sensitive surface of the substrate. For this purpose, a focusing device is provided, by means of which the length of the optical path between the mask and the useful element can be changed without the imaging scale being influenced. The focusing device is expediently part of the optical unit.

In a preferred embodiment of the invention, only a small part of the mask is imaged on the useful element at any time and / or in each case by means of the optical unit. The overall picture on the useful element is between by relative movement On the one hand, the mask and substrate are created in relation to the optical unit, which is also referred to as imaging optics. It is particularly important that the position of the mask with respect to the substrate is not changed during the exposure. The mechanical movement between the optical unit, preferably also the illumination unit, on the one hand, and the mask and the substrate, on the other hand, is advantageously carried out as slowly as possible, the quite high speeds and accelerations that are fundamentally possible with the mechanical system not being exhausted in order to to keep the forces on the optical components or the mask and the substrate as low as possible. The mechanical system preferably contains a cage, by means of which the mask and the substrate are fixed to one another and arranged in the required manner. On the one hand, the largest possible image field is aimed at in order to keep the necessary mechanical movements or cage movements for assembling the overall image small. On the other hand, a small image field is sought so that the distortion, in particular scaling, according to the invention can be carried out. The small image field required for the distortion is moved comparatively quickly over the mask and the useful element by means of the optical unit. For this purpose, a light scan perpendicular to the direction of movement of the mechanical system or the cage is advantageously provided. The movement of the illuminated area on the mask, hereinafter referred to as the illumination spot, is composed of two movements. The mechanical system or the cage expediently moves relatively slowly relative to the optical unit, in the order of magnitude of 0.1 to 1 m / sec. The illumination spot, on the other hand, moves comparatively quickly relative to the optical unit or imaging optics, preferably in the order of 1 to 10 m / sec.

In a preferred embodiment of the invention, the image is composed of several partial images, the following fact being taken into account for the joints at the edge of the respective partial images. If the drawing files do not fit together exactly, there are gaps in the overall picture, which is therefore unusable. On the other hand, if the partial images overlap, overexposure can occur in such multiple-imaged areas, the structure sizes in multiple-exposed areas of the light-sensitive layer of the substrate being able to deviate from the desired value. Therefore, according to the invention, the exposure intensity is reduced in the edge areas in which partial images overlap. This is achieved in an advantageous manner an illumination unit or a light source is used which has an at least approximately Gaussian beam profile and / or a light intensity distribution at least approximately in accordance with a Gaussian distribution curve.

The method according to the invention and the device proposed for carrying out the same enable the mask to be imaged on the substrate arbitrarily and / or taking account of distortions of the substrate or the useful element, the imaging optics or optical unit together with the illumination unit relative to the mask and the substrate is moved. The image field of the imaging optics is preferably smaller than the entire image and provides a predetermined number of individual images. The entire image of the mask is thus composed of individual images. The respective individual image is moved on the substrate by means of active adjustment elements in the imaging optics or the optical unit in the XY plane. By correspondingly controlling the adjustment elements mentioned, the overall image is composed of the individual images in such a way that the required distortion in the overall image is achieved.

Said distortion is calculated and / or predefined by measuring marks, in particular alignment marks, on the mask and the substrate or by specifying distortion values, it also being possible to advantageously carry out a combination of measured values and predefined values. Based on the measurement mentioned, relative positions of markings of the mask to markings of the substrate are determined. For the correction method according to the invention, the image is distorted such that the markings on the substrate are imaged. The mask and / or the substrate can be corrected here.

Image distortion and / or alignment is preferably carried out by overlapping and / or continuous joining of individual images, each of which is smaller than the overall image of the mask. The distortions are carried out in particular by translation, rotation, shear or direction-dependent scaling. In an advantageous manner, an at least approximately constant intensity over the mask surface is predetermined on average over time by softly fading out the illumination intensity and / or overlapping the individual illumination spots. The illuminated area of the mask is over the optical unit or imaging optics mapped onto the substrate, the imaging representing the structure of the mask with the intensity profile of the illumination on the substrate and / or an at least approximately constant image intensity being achieved on the substrate over time. In a preferred manner, a Gaussian intensity distribution of the illumination spot is predetermined, in particular by using a laser as the light source.

Furthermore, within the scope of the invention, the movement of the illumination spot on the mask is composed of two movements, with a rapid scan movement of the illumination and / or the illumination spot on the one hand and a relatively slower movement of the mechanical unit, in particular a cage, on the other hand, on which the Mask and the substrate are adjusted and fixed. Furthermore, a correction unit and control unit are provided which, depending on the position of the illumination spot on the mask, controls the correction unit, which in particular is integrated in the optical unit. In particular, the composite movement of the illumination spot on the mask is taken into account.

In a special embodiment, the lighting intensity on the mask is controlled by controlling the lighting unit or assigned controllable damping elements. This can be done in particular in the case of pulsed lasers by varying the pulse rate. Furthermore, the lighting intensity can be controlled as a function of the position of the lighting spot on the mask. Additionally or alternatively, the lighting intensity can be controlled as a function of the speed of the mechanical unit or the cage. This advantageously achieves an at least approximately constant intensity distribution on average over the mask, although the speed of the mechanical unit is not constant.

Calibration of the optical path is advantageously carried out, a reference structure, which is referred to as an adjustment camera, being imaged on a camera, which is preferably fixed on the table of the mechanical unit, using a light source provided for this purpose or with the existing light source of the illumination unit. In addition, the light path is expediently readjusted, specifically via the active elements in the optical path and / or the optical unit. There is a calibration the optical measuring devices on the reference mark and the camera of the table.

In a further embodiment of the invention, the optical unit contains two lenses or lens systems in a so-called 4f arrangement, the mask being arranged in the front focal point of the first lens system. The substrate is arranged in the rear focal point of the second lens system. Here, the beam path is mirrored in front of the first lens system or after the second lens system, in particular via a retroreflector. Furthermore, it has proven to be advantageous to combine the imaging optics or optical unit with a correction unit in such a way that the image is shifted perpendicular to the optical axis in the image plane. Depending on the specific requirements, the following measures are provided individually or in combination. By means of a plane-parallel plate, the beam is displaced parallel to the optical axis by tilting perpendicular to the optical axis. Furthermore, a mirror can be provided, which can be tilted perpendicular to the perpendicular of the incident and emerging rays. Furthermore, a retroreflector can be provided, which can be displaced perpendicular to the optical axis. Furthermore, to calibrate the optical path, the light path can be lengthened or shortened by means of the imaging optics, preferably by moving the retroreflector mentioned. As a result, the image plane can be expediently imaged precisely on the substrate surface. The setting of the image plane can either be set statically by specifying the setpoint or dynamically by measuring the position of the substrate surface.

A plurality of, preferably parallel, beam paths are preferably used to increase the throughput of the system or the device. In this case, the illumination unit generates a plurality of illumination spots on the mask, which are imaged on the substrate by a plurality of optical units and / or imaging and correction units. Furthermore, a mask can advantageously be reproduced by generating a plurality of parallel beam paths with a plurality of illumination spots on the mask. Within the scope of the invention, a mask can also be reproduced in that a plurality of parallel beam paths are generated on the substrate by means of a beam splitter in the optical unit. Special refinements and developments of the invention are specified in the subclaims and in the following description of the figures.

The invention is explained in more detail below on the basis of the exemplary embodiments illustrated in the drawing, without there being any limitation in this regard. Show it:

1 shows a basic illustration of a correction or image distortion by joining individual images together,

2 shows a schematic illustration of an exemplary embodiment of the device,

3 shows a schematic illustration of a device for distorted imaging of a mask,

4 shows a schematic diagram for the vectorial addition of the lighting position from the position of the mechanical unit and the lighting unit,

5 shows a schematic illustration of overlapping illumination spots of an illumination unit with Gaussian intensity distribution in a spatial direction,

6 shows an exemplary embodiment of an optical unit with two lens systems in a so-called 4f arrangement with a retroreflector that is adjusted,

7 shows a schematic illustration of an illumination unit for generating two illumination spots on the mask,

8, 9 schematically show arrangements for the simultaneous duplication of masks or for multiple imaging. Fig. 1 shows the principle of image distortion by joining individual images together. A partial area of the mask 1 is imaged on the substrate 2, an illumination spot 3 being generated on the mask 1 by means of an illumination unit and depicted as an individual image 5 on the substrate 5. The entire image is composed of overlapping individual images 5, each individual image being an undistorted 1: 1 image of the mask or the associated respective lighting spot. The distortion of the overall image arises from a displacement of the individual images 5 on the substrate 2 by a correction vector 4. The distortion of the substrate 2 is calculated by measuring markings, in particular alignment marks, on the mask 1 and the substrate 2 or by specifying distortion values , whereby a combination of measured values and default values can also be carried out in an expedient manner. On the basis of the measurement, the relative positions of mask marks to substrate marks are determined, the image being distorted in accordance with the correction method in such a way that the mask marks are imaged on the substrate marks mentioned. Here, the mask 1 or the substrate 2 and, if necessary, both can be corrected. The said displacement causes a blurring in the overlap area 6, the maximum offset of two adjacent individual images 5 being predefined in accordance with the tolerable blurring and the size of the overlap area 6.

FIG. 2 shows a schematic representation of an embodiment of the device, the mechanical unit of which contains a cage 7, by means of which the mask 1 and the substrate 2 are spaced apart and firmly fixed to one another. An illumination unit 8, an optical unit 9, a mask camera 10 and a substrate camera 11 are arranged separately from the mechanical unit or the cage 7. On the cage 7, an adjustment camera 12 and a reference mark 13 are also fixed. An X drive 15 and a Y drive 16 are provided for moving the cage 7 in the XY plane. According to the invention, the cage 7 and the components fixed on it can be moved relatively relative to the other components, such as, in particular, lighting unit 8, optical unit 9, which are fixedly mounted to one another and are in a defined geometric association with one another. The mask 1, the substrate 2 and the adjustment camera 12 with the cage 7 are thus arranged so as to be relatively movable relative to all other components of the device. By means of the illumination unit 8, the mask 1 is backlit in a partial area, the aforementioned illumination spot 3. This partial area or illumination spot 5 is imaged on the substrate 2 without distortion and without being enlarged via the optical unit 9. The optical unit 9 contains an imaging and correction unit and is located in the optical path between the mask 1 and the substrate 2. By means of the correction unit mentioned, the respective individual image on the substrate 2 is shifted in the XY plane. To determine the distortion thus achieved, the positions of registration marks 13 are determined on the mask 1 and the substrate 2 by means of the camera and downstream image processing software of an image processing system. The control data for the imaging and correction unit mentioned are recalculated from the positions of the registration marks 14.

To adjust the optical path, the cage 7 is moved into a position in which the reference structure or reference mark 13 is backlit by the lighting unit 8. The reference mark 13 is imaged on the adjustment camera 12 by means of the optical unit 9, which forms the imaging and correction unit. The image of the reference mark 13 is mapped to a standard position on the adjustment camera 12 by appropriate activation of the correction unit of the optical unit. The coordinate system of the mask 1 is thus related to the coordinate system of the substrate 2. The control values determined here are taken into account as offset values in the correction calculation for the subsequent mask mapping. The reference structure or reference mark 13 is then moved under the mask measuring camera 10 and the position of the reference mark 13 is measured. This determines the position of the mask camera 10 in relation to the reference mark 13. The same procedure is followed with the substrate camera 11, the position of the CDC chip in the adjustment camera 12 being used in particular as a reference mark. The position of the mask camera 10 and the substrate camera 11 thus determined are taken into account as offset values when measuring alignment marks on the mask and / or the masks or the substrate and / or the substrates.

FIG. 3 shows a schematic overview of a device for distorted imaging of the mask 1. A laser 17 is provided as the light source of the mentioned illumination unit, which preferably has an average power of 1 to 10 W in a usual wave range for exposing printed circuit boards in the range of 350 to 400 nm. The beam expansion unit 18 is used for the respective application. required lighting diameter set. The expanded laser beam is moved perpendicular to the surface of the mask 1 by means of a scanning device 19. As already explained, the mask 1 and the substrate 2 are held firmly on the cage 7 of the mechanical unit. The optical unit 9 with active elements for position correction and for imaging the illumination spot 3 on the substrate 2 is arranged in the optical path between the mask 1 and the substrate 2. The optical unit 9 contains a plane-parallel plate 20 with a 2-axis tilt drive 21, a lens system or a lens 22, a scanning mirror 23 with an associated 2-axis tilt drive 24, a second lens system 22 and a retroreflector 25 with an associated XYZ drive 26. The image field of the image is so large that the entire illuminated area of the mask 1 is imaged onto the substrate 2 in each position of the illumination scan. The cage 7 can be moved relative to the lighting unit 8 and the optical unit 9 in the required manner by means of the aforementioned XY drives with a position control 27. The position control or regulation of the cage 7, the active elements 20, 23, 25 of the optical unit, the laser 17 and the scanning device or the illumination scanner 19 are connected to a computer system 28 and / or are controlled by means of the computer system 28. To determine the measurement data required for the corrections, an image processing system 29 is assigned to the computer system 28 or integrated therein, the cameras mentioned above being connected to the image processing system 29. The positions of registration marks in the camera images are calculated by means of the image processing system 29, and the absolute position on the mask 1 and / or the substrate is calculated using the detected cage position. A reference mark 13 is arranged on the level of the mask 1 of the cage 7 and the adjustment camera 12 is arranged on the level of the substrate 2. The reference mark 13 is imaged on the adjustment camera 12 by means of the optical unit. In this way, said active elements 20, 23, 25 of the optical unit are readjusted if necessary. The entire computer system 28 is controlled via an operating computer 13, which is assigned a suitable user interface, in particular on a screen or monitor.

The lighting intensity on the mask 1 is advantageously controlled by actuating the lighting source, in particular the laser 17, via the computer system 28. For example, in the case of a pulsed laser 17, the pulse rate is varied, or in the case of a CW laser, by controllable damping intensity affected. The system data, in particular the position of the illumination spot on the mask or the speed of the table or the cage 7, are made available to the computer system 28 at all times. The intensity is thus controlled as a function of the named and / or other parameters. Furthermore, the intensity is adapted to different speeds of the cage 7 in such a way that the predetermined and / or desired intensity distribution is given in total on the mask 1. This ensures that the exposure can be carried out during the acceleration and / or braking phase of the cage 7.

The device according to the invention has the following structure.

1. Illumination path with light source, in particular laser 17, expansion optics or beam expansion 18, illumination scanner or scanning device 19.

2. A mask holder which is adapted to different mask types, such as chrome masks, emulsion masks or films.

3. Optical unit 9 with input optics, XY scanner, output optics and focus device.

4. substrate holder, which is adapted to various useful elements, such as thin films, continuous films, printed circuit boards or glass substrates.

As shown in FIG. 4, the position of the illumination spot 3 on the mask 1 is determined by the XY position of the cage and the position of the illumination scanner 19. The combination of a rapid scan movement 32 with a relatively slow cage movement 31 results in a strip-wise illumination of the mask 1. The optical unit 9 is designed in such a way that it can image the illumination spot 3 in all scan positions on the substrate 2. According to the invention, the movement of the illumination spot 3 is set such that the illuminated areas overlap. Due to the overlap together with the Gaussian intensity distribution, an approximately constant intensity distribution over the surface of the mask to be illuminated is achieved on average. The illumination intensity is gently faded out, the illumination intensity in the edge region of the illumination spot 3 being smaller by a predetermined amount than in the center of the illumination spot 3, preferably according to the Gaussian intensity distribution of the laser. The illuminated area of the mask 1 is over the optical Unit 9 mapped onto the substrate 2, the image being the structure of the mask 2 with the intensity curve of the illumination. An at least approximately constant image intensity on the substrate 2 is thus achieved on average.

The intensity of the lighting is controlled by the computer system. This can be done by controlling the lighting source or controllable damping elements, for example by means of a pulsed laser by varying the pulse rate. Furthermore, the illumination intensity is controlled as a function of the position of the illumination spot 3 on the mask 1. Furthermore, the intensity of the illumination is specified as a function of the speed of the cage within the scope of the invention, so that a constant intensity distribution on the mask 1 over time is reached, although the speed of the cage is not constant. In addition to the variation of the pulse rate in the case of pulsed lasers, in particular in the case of a CW laser, the intensity of the lighting can be predetermined by controllable damping. The system data, such as in particular the position of the illumination spot 3 on the mask 1 or the speed of the cage or its table, are available to the computer system at all times. It is thus possible to control the intensity of the lighting as a function of further parameters. The intensity is expediently adapted to different speeds of the cage in such a way that the desired intensity distribution is given in total on the mask 1. Exposure can thus advantageously be carried out during the acceleration or deceleration phase of the cage.

The soft masking out of the illumination intensity and overlapping of the illumination spots is specified in particular by means of a laser, the beam intensity of which has a Gaussian profile perpendicular to the beam direction. The control of the lighting intensity and thus the setting of the light intensity is advantageously carried out by varying the pulse rate of the pulsed laser. The rapid movement of the illumination spot 3 in comparison to the cage movement is preferably generated by deflecting on a scanning mirror of the illumination scanner 19.

For the correction method according to the invention, the image on the substrate is distorted in such a way that the mask marks are imaged on the substrate marks, it being irrelevant whether the mask 1, the substrate 2 or both are corrected. These various arbitrary correction options require that the correction Vector Δx and Δy depend on the position of the illumination spot (xb, yb) on mask 2 according to the following equation:

Δx = f _Λ (x _b , y _b ) Δy = / ₂ (x _b > y _b )

The lighting position is vectorially added from the cage position and the scan position. A correction device and control are used in such a way that, depending on the position of the illumination spot 3 on the mask 1, the correction unit of the optical unit 9 is controlled accordingly, the combined movement explained in particular being taken into account. The correction unit is designed in such a way that both the fast scanning movement and the cage movement 31, which is comparatively slower, can take place. The control of the correction device ensures that the position of the illumination spot is determined from the position of the table or the cage and the scan position. The control signals for the correction unit are preferably calculated and generated from these positions in real time and taking into account the predefined corrections, advantageously in accordance with the following equation:

f _b λ γ XK-a., fig f ^ XscPan

W ysca /

In order to ensure long-term stability of the device, the mechanical unit or the cage 7 contains the reference mark 13 and the adjustment camera 12. The reference mark 13 is arranged on the mask level and the adjustment camera 12 is mounted on the substrate level. By imaging the reference structure or reference mark, in particular with the exposure source contained in the illumination unit 8 or alternatively with a separate exposure source, on the fixed adjustment camera 12, the optical path is preferably calibrated. The readjustment of the optical path between the mask 1 and the substrate 2 is advantageously carried out via one of the active elements of the optical unit 9. The optical measuring devices are advantageously calibrated using the reference mark 13 and the table camera and / or the adjustment camera, which is arranged on the substrate level. The cage position in the XY plane is continuously monitored by a measuring system. Lich measured. The cameras and the measuring system mentioned are connected to the computer system, by means of which the measured values are evaluated and the drives of the cage and the correction devices are controlled in accordance with the correction values and / or correction vectors determined in this way.

Any image distortion and alignment is advantageously carried out by overlapping or continuous joining of individual images that are smaller than the overall image. Special cases for the distortions provided for correction according to the invention are translation, rotation, shear and direction-dependent scaling. By so-called soft fading out of the illumination intensity and overlapping of the illumination spots 3, an approximately constant intensity over the mask area is advantageously achieved on average over time. The illuminated area or illumination spot 3 of the mask is imaged onto the substrate 2 via the imaging optics. The image thus generated is the structure of the mask with the intensity curve of the lighting. An at least approximately constant image intensity on average over the substrate 2 is advantageously achieved. For this purpose, a laser is advantageously used as the light source, the beam intensity of which has a Gaussian profile perpendicular to the beam direction. In addition, the light intensity can be predetermined in a preferred manner, in particular by varying the pulse rate of a pulsed laser. The rapid movement of the illumination spot on the mask 1 is generated in particular by deflecting it by means of a scanning mirror of the illumination scanner 19.

5 shows the overlap, for example, in a spatial direction of lighting spots 3, with lighting using Gaussian profiles or a Gaussian intensity distribution as the basis. As a result of the predetermined overlap of the curves, the sum intensity 34 on the mask is sufficiently constant except for a residual ripple. The lower the desired ripple, the greater the overlap area 6 of the Gaussian profiles. When the individual images 5 are corrected, that is to say shifted in the XY plane, the overlap area changes. The change in the overlap area 6 is specified to be small relative to the absolute size. This results in only a slight change in the ripple, so that the light intensity 35 on the substrate is at least approximately constant. It should be noted that the image on the substrate matches the structure of the mask the intensity curve of the lighting. An approximately constant image intensity on average over the substrate is thus achieved.

FIG. 6 shows an exemplary embodiment of the optical unit, comprising two lens systems 22, which can each also be designed as individual lenses. The two lens systems 22 form a so-called 4-fold arrangement with a retroreflector 25 arranged downstream in the light path. With such an arrangement, an approximately 1: 1 individual image 5 is generated on the substrate 2 from the object or the illumination spot 3 of the substrate 1. Such an image is undistorted and not mirrored. By moving the retroreflector 25 in the Y direction, the image plane is set on the substrate 2. In combination with the measuring system with which the position of the substrate surface in the Z direction is detected, the image plane can be set once or continuously adjusted within the scope of the invention. Three active elements are provided in the optical path, which, depending on the application, are contained individually or in different combinations, in particular in the optical unit. With at least one, advantageously with all active elements, the image field and / or the image is shifted in the XY plane. The image field is shifted perpendicular to the optical axis by tilting the axially parallel plate 20. The image field is also shifted by tilting the scanning mirror 23 by means of the 2-axis tilting drive 21 perpendicular to the perpendicular from the incident and reflected beam. Furthermore, the image field is shifted by moving the retroreflector 25 in the XZ plane.

Furthermore, an increase in the exposure speed and thus in the throughput of the device is advantageously achieved by providing a plurality of imaging and correction units in parallel. Several illumination spots are generated on the mask, which are imaged on the substrate by several imaging and correction units. For this purpose, as shown in FIG. 7, the illumination unit is designed such that at least two illumination spots 3 are generated on the mask. The correction values or vectors 4 are preferably predetermined independently of one another by means of the two separate optical units 9.

8 and 9 show arrangements for the simultaneous duplication of the masks. At least two, and possibly more, imaging and correction units arranged in such a way that a mask 1 is reproduced simultaneously on one or more substrates 2. 8 shows the double image by way of example, two illumination spots 3 being present due to two parallel beam paths. According to FIG. 9, a single illumination spot 3 is generated on the mask 1 and the optical unit contains a beam splitter 37, by means of which two parallel beam paths are generated by means of the optical unit 9 in order to generate two individual images 5. It goes without saying that, in the context of the invention, instead of two individual images, a larger number of individual images can be generated analogously.

reference numeral

Mask substrate / useful element illumination spot correction vector single image overlap area mechanical unit / cage illumination unit optical unit / imaging and correction unit mask camera substrate camera alignment camera reference mark registration mark X-drive Y-drive laser beam expansion unit lighting scanner adjustment element / plane-parallel plate 2-axis tilt drive of 20 lens system / lens adjustment element / scan element 2-axis tilt drive of 23 adjusting element / retroreflector XYZ drive of 25 position control for cage drive Computer system Image processing system Operating computer with user interface Cage movement Scanning movement Sum intensity on the mask Sum intensity on the substrate Mirror Beam splitter

Claims

claims

1. A method for imaging a mask (1) on a substrate (2), the mask (1) being imaged on the substrate (2) by means of an illumination unit (8) and an optical unit (9), characterized in that the Illumination unit (8) and the optical unit (9) are moved relative to the mask (1) and the substrate (2), that distortions of the substrate (2) are detected, and that, depending on the detected distortions, by means of the optical unit (9) the

Illustration of the mask (1) distorted and the distortions of the substrate (2) is adjusted.

2. The method as claimed in claim 1, characterized in that the entire image of the mask (1) is composed of, in particular, overlapping individual images (5), the image field of the optical unit (9) being specified to be smaller than the overall image that the individual images ( 5) are moved on the substrate (2) by means of active adjusting elements (20, 23, 25), in particular the optical unit, and / or by controlling the adjusting elements (20, 23, 25) the individual images (5) are assembled in such a way, that the required distortion of the overall image is achieved, each individual image being an undistorted 1: 1 image of the mask (1).

3. The method according to claim 1 or 2, characterized in that the distortion of the substrate (2) by measuring marks (14) of the mask (1) and the substrate (2) or by specifying distortion values is calculated and / or that a A combination of measured values and default values is carried out and / or that relative positions of marks (14) of the mask (1) to marks (14) of the substrate (2) are determined and / or that the image is distorted for correction such that the marks ( 14) of the mask (1) are imaged on the marks (14) of the substrate (2), the mask (1) and / or the substrate (2) being corrected.

4. The method, in particular according to one of claims 1 to 3, characterized in that the required distortion of the image of the mask (1) and / or an alignment is carried out by overlapping or continuous joining of individual images, which are each smaller than the entire image the mask (1), the distortions being carried out in particular by translation, rotation, shearing or direction-dependent scaling.

5. The method according to any one of claims 1 to 4, characterized in that the illumination spots (3) are provided overlapping on the substrate (2) and / or that the illumination intensity of the illumination spots (3) is faded out and / or in their edge zone compared to their Center is reduced and / or that the illumination spot (3) has a Gaussian distribution of the illumination intensity and / or that a laser is used as the light source.

6. The method according to any one of claims 1 to 5, characterized in that the movement of the illumination spot (3) on the mask (1) is composed of two movements, preferably from a rapid scanning movement of the illumination and a slower movement of the mask ( 1) and the substrate (2) receiving mechanical unit (7) and / or that the correction of the individual image (5) on the substrate (2) is controlled according to the position of the illumination spot (3) on the mask (1) and / or that to correct and / or control the lighting spot (3), the composite movement is taken into account.

7. The method according to any one of claims 1 to 6, characterized in that the illumination intensity on the mask (1) is controlled by controlling the illumination source or a controllable damping element and / or that the illumination intensity is controlled using a pulsed laser by varying the pulse rate and / or that the illumination intensity is controlled as a function of the position of the illumination spot (3) on the mask (1) and / or that the illumination intensity is controlled as a function of the speed of the mechanical unit receiving the mask (1) and the substrate (2) becomes.

8. The method according to any one of claims 1 to 7, characterized in that a calibration of the optical path by imaging a reference mark (13) or reference structure by means of an exposure source, in particular the exposure source contained in the lighting unit (8) on an adjustment camera (12) - which, like the mask (1) and the substrate (2) and together with them, is arranged on the movable mechanical unit and / or that a readjustment of the optical path by means of at least one active element (20, 23, 25), in particular the optical unit (9) is carried out and / or that the optical measuring devices are calibrated, in particular by means of an adjustment camera (12) and a reference mark (13) which are arranged on the movable mechanical unit (7).

9. Device for imaging a mask (1) on a substrate (2), comprising a mechanical unit (7) on which the mask (1) and the substrate (2) are arranged at a distance from one another, an illumination unit (8) for generating a Illumination spot (3) on the mask (1) and also containing an optical unit (9) in the optical path between the mask (1) and the substrate (2), by means of which the illumination spot (3) can be imaged on the substrate (2) , wherein the mechanical unit (7) contains at least one drive (15, 16), characterized in that the mechanical unit (7) is designed to hold the mask (1) and the substrate (2) in a manner that cannot be changed during the image Mechanical unit (7) for the lighting unit (8) and the optical unit (9), which are fixedly coupled to one another, is movably arranged and that the optical unit (9) contains at least one active adjusting element (20, 23, 25) for adjusting the Lighting spots (5 ) on the substrate (2), the adjusting element (20, 23, 25) being controllable as a function of distortions of the substrate (2).

10. The device according to claim 9, characterized in that the image field of the optical unit (9) and / or the individual image (5) generated by means of this is smaller than the entire image of the mask (1), the entire image of the mask (1 ) can be put together from a predetermined number of said individual images (5), and that a computer system (28) for controlling the active adjusting element (20, 23, 25) is designed in such a way that, depending on the detected distortions and / or corresponding distortions the entire image of the mask (1) can be carried out by assembling the correspondingly deflected individual images (5).

11. The device according to claim 9 or 10, characterized in that the adjusting device has a cage (7) which is designed for mutually fixed and spaced arrangement of the mask (1) and the substrate (2) that the optical unit (9) is arranged in the cage (7) between the mask (1) and the substrate (2) and / or that the optical unit (9) and the lighting unit (8), which are mechanically coupled to one another, relative to the cage (7) are arranged to be movable and / or the cage (7) is arranged to be movable with respect to the optical unit (9) and the lighting unit (8) by means of drives (15, 16).

12. Device according to one of claims 9 to 11, characterized in that the optical unit (9) contains an imaging optics with two lenses or lens systems (22) in a 4f arrangement in particular, that the mask (1) in the front focal point of the first Lens or the first lens system (22) is arranged and the substrate (2) of the second lens or the second lens system (22) is arranged, the beam path in front of the first lens or the first lens system (22) or after the second lens or the second lens system (22) is point mirrored via a retroreflector (25).

13. Device according to one of claims 9 to 12, characterized in that the optical unit (9) contains a correction unit and / or an adjusting element (20, 23, 25), in particular for shifting the image perpendicular to the optical axis in the image plane and / or that a plane-parallel plate (20) is provided, by means of which the beam can be displaced parallel to the optical axis by tilting perpendicular to the optical axis and / or that a mirror (23) is provided which can be tilted perpendicular to the perpendicular of the incoming and outgoing beam is arranged and / or that a retroreflector (25) is provided which is displaceable perpendicular to the optical axis.

14. Device according to one of claims 9 to 13, characterized in that the retroreflector (25) is movably arranged such that the light path in the imaging optics can be extended or shortened and thus the image plane can be reproduced exactly on the surface of the substrate (2) , the setting of the image plane statically by setting the target value or dynamically by measuring the position of the surface of the substrate

(2) is adjustable.

15. Device according to one of claims 9 to 14, characterized in that the lighting unit for generating at least two lighting spots

(3) is formed on the mask (1), which a corresponding number of optical Units (9) with imaging and correction units are arranged downstream to generate at least two or more individual images (5) on the substrate (2).

16. The device according to one of claims 9 to 15, characterized in that for in particular simultaneous reproduction of the mask (1) on one or more substrates (2), the lighting unit (8) for generating a plurality of lighting spots (3) on the mask (1) and / or that a beam splitter (37) is arranged in the optical path between the mask (1) and the substrate (s) (2) in such a way that several individual images () through several, preferably parallel beam paths on the substrate (s) (2) 5) can be generated.

17. The device according to one of claims 9 to 16, characterized by the training for performing the method according to one of claims 1 to 8.