Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70383—Direct write, i.e. pattern is written directly without the use of a mask by one or multiple beams
  • G03F7/704—Scanned exposure beam, e.g. raster-, rotary- and vector scanning
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/20—Exposure; Apparatus therefor
  • G03F7/2051—Exposure without an original mask, e.g. using a programmed deflection of a point source, by scanning, by drawing with a light beam, using an addressed light or corpuscular source
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70283—Mask effects on the imaging process
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70283—Mask effects on the imaging process
  • G03F7/70291—Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70358—Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
  • G03F7/70466—Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
  • G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
  • G03F7/70558—Dose control, i.e. achievement of a desired dose

Definitions

• the present invention relates to a method according to claim 1 and an apparatus according to claim 7.
• Lithographic techniques in the semiconductor industry can be roughly divided into two major areas, imprint lithography and
• Photolithography In most cases, masks are used in photolithography to reproduce a structure in a photosensitive material. These masks can either be scaled down onto the photosensitive material layer using projection techniques or the mask structure can be transferred into the photosensitive material without optical scaling. The production of the masks is time-consuming, cost-intensive and prone to errors.
• Lithography techniques developed. These techniques are based on the
• Pixels are exposed simultaneously and after exposure there is a relative shift between the photosensitive material and the optical system that is responsible for the pixel exposure.
• these are scanning methods.
• Gray-tone lithography has recently been used to enable a three-dimensional or 2.5-dimensional photolithographic exposure of a photosensitive material and thus a structuring of the
• Exposure step is preceded by a coating process and each
• Exposure step follows a development step. Only after the
• the masks made of the photosensitive material can be used for etching or for the metal coating.
• the maskless exposure technologies were expanded to include black-and-white or gray-tone lithography, with the help of which a photosensitive material could be exposed not only two-dimensionally but three-dimensionally. Experience has shown, however, that the used
• a micromirror device Digital Micromirror Device, hereinafter: DMD
• DMD Digital Micromirror Device
• step processes step-and-repeat
• the image points are continuously moved in relation to the optics, several secondary beams are controlled individually by means of the optics for individual exposures of each image point by the
• Secondary beams are placed in either an ON or an OFF state, with
• a plurality of secondary beams are controlled individually by means of the optics for individual exposures of each pixel, the secondary beams being defined in an ON or an OFF state or in a state between the ON and the OFF state Intermediate state.
• the invention relates to a device for exposing image points of a photosensitive layer consisting of a photosensitive material on a substrate by means of an optical system with the following features: Means for the continuous movement of the pixels
• Individual doses D can be defined.
• the invention particularly describes several methods and one
• the invention is based primarily on several different methods for producing this photolithographic exposure.
• the basic idea is based on (i) multiple exposure of a pixel by, in particular, immediately following mirrors of a DMD s and / or (ii) the use of a mathematical algorithm for setting a pixel pattern and / or (iii) on variation / control of the radiation intensity of the Light source and / or the dose per pixel.
• 2.5 dimensional and three-dimensional photolithographic exposure are subsequently used synonymously for the further dimension of the gray levels or multiple exposure of individual pixels.
• a core of the invention consists in particular of a plurality of methods which are independent of one another but can be used together, by means of which a 2.5-dimensional, photolithographic exposure is made possible.
• the procedures differ technically
• Step process no step-and-repeat, and / or
• each mirror can only be switched between two states (ON-OFF) and / or
• Points in time in particular by oversampling and / or (vi) using mathematical algorithms to generate a pattern and / or
• a main idea of the invention is, above all, that the generation of a gray tone lithography by using at least one of the processes according to the invention, in particular under simultaneous
• the method according to the invention preferably uses a scanning method, i.e. a continuous
• the throughput is significantly increased, since the relative movement between the DMD and the photosensitive material is not stopped or at least slowed down after each step, in order to control the exposure of the DMDs in the photosensitive material by, in particular, individually controlling the mirrors
• High volume manufacturing (HVM) suitable.
• the method consists in particular in that all mirrors of the DMD are switched simultaneously / synchronously, i.e. all mirrors will be
• the DMD s therefore do not have to be set individually at one position, ie the mirrors of the DMD are always switched in synchronism.
• An essential aspect is the possibility of the targeted adjustment of a gray tone in a pixel by the repeated exposure of several mirrors, which are located along a line parallel to the relative movement direction.
• Another, additional aspect of the invention is not only the targeted adjustment of the gray tone by oversampling, but also
• the methods disclosed according to the invention enable gray-tone exposure in different and / or combined ways.
• the methods according to the invention can be used in particular to replace gray tone masks and / or multiple exposures.
• the substrate holder is precisely controlled and positioned, in particular during the continuous exposure, the position of the optics (DMD) and the layer to be exposed, preferably continuously, being checked, in contrast to the step process. Exposure, movement and, if appropriate, also the measurement of the areas already exposed are in particular carried out, monitored and simultaneously controlled.
• the control electronics and / or software must be set up for this.
• the behavior of the lacquer over a wide intensity range is, in particular, relevant to the control in order to obtain further optimized results.
• the number of gray tones is therefore limited by the number of
• Mirror exposure lines that sweep over a pixel.
• the mirror exposure lines grouped into blocks.
• the set of all mirror exposure lines that can be used to set a gray tone are referred to as the mirror exposure line block.
• the following example is given as an example. Using a DMD with 900 mirror exposure lines, a pixel with one of 900 shades of gray or 900 different shades of gray can be generated. If you group the 900 mirror exposure lines into three blocks of 300 mirror exposure lines each, a pixel can only take on one of 300 shades of gray, but three pixels can do the same
• the methods according to the invention serve to produce exposed 2.5-dimensional structures in a photosensitive material.
• the invention shows several methods to image pixels in the
• Lateral exposure means the exposure of a pixel in the plane parallel to the surface of the photosensitive material.
• Vertical exposure is an exposure of the photosensitive material at a pixel to a defined depth.
• LCDs liquid crystal displays
• LCoS liquid crystal on silicon
• GLVs grating light valve
• All mentioned methods according to the invention can also be used to ensure the quality of the classic, binary, maskless To improve exposure lithography.
• edge effects can be reduced by the methods mentioned.
• a pixel is understood to be a defined, exposed position in the photosensitive material, which is generated by a single mirror of the DMD.
• the image point is thus a spatially limited area on the photosensitive material to be exposed.
• the photosensitive material can be exposed to a defined depth.
• Each pixel thus has not only a lateral, but also a vertical extension. The pixel is therefore three-dimensional. The vertical extent, i.e. the depth of the
• the depth in which the photosensitive material is exposed is determined in particular by the dose.
• One of the most important methods according to the invention for defining the dose of a pixel is repeated exposure through several DMD mirrors. These DMD mirrors are arranged, in particular in a line parallel to the relative direction of movement of the DMD mirrors, one after the other, in each case being alignable on the same image point.
• the DMD levels can be controlled in such a way that s either projects the same defined dose onto the pixel per unit of time or not (ON-OFF).
• a shade of gray results from the amount of photosensitive material of the pixel that has received a defined dose and has been chemically modified accordingly. The higher the dose received, the more photosensitive material was chemically and / or physically altered in depth.
• a pixel line means a set of pixels that are distributed along a straight line normal to the relative direction of movement on the photosensitive material, in particular equidistantly.
• a pixel column means a set of pixels which are distributed along the straight line parallel to the relative movement direction on the photosensitive material, in particular equidistantly.
• a pixel area is understood in the further course of the text to be a set of, in particular neighboring, pixels.
• Pixels of the pixel area are exposed in particular by a mathematical algorithm in such a way that the resulting one
• Pixel area has an averaged gray tone value. This averaged gray tone value is based in particular on the algorithm used, with which the individual gray tone values of the pixels are controlled. When using mathematical algorithms to determine a
• the pixel area (and not the pixel) represents the actual pixel in gray tones.
• the greatest possible resolution is defined in the pixel areas.
• the magnitude of the pixel area and the dimensions of a DMD mirror, more precisely the projection of the DMD mirror, are approximately the same.
• the area of the pixel region is in particular greater than 0.5 times, preferably greater than 0.75 times, more preferably exactly 1.0. times, most preferably greater than 1.5 times, most preferably greater than 2.0 times the area of the projected DMD area.
• An exposure strip describes a set of pixels along a direction, in particular in the direction of the longest movement distance of the DMD. For example, with a meandering raster path, the DMD is always moved along a longest possible movement path, which extends in particular to the edge of a substrate, and by a short lateral movement from one movement path to the next
• a primary beam is understood to mean that through a
• Radiation source / primary source / light source generated light beam before it strikes the DMD Radiation source / primary source / light source generated light beam before it strikes the DMD.
• the primary beam originates in the light source and in particular passes through several optical elements before it strikes the DMD.
• a secondary beam is understood to mean that part of the primary beam which is reflected, in particular, by a, preferably individual, mirror of the DMD.
• a primary beam is therefore broken down into several secondary beams by the DMD.
• the secondary beam has its origin in a mirror of the DMD and can pass through several optical elements before it strikes the photosensitive material.
• an intensity profile is understood to mean the cross-sectional intensity distribution of a secondary beam which, in particular with its predominant intensity component of the intensity profile, illuminates a pixel.
• the intensity profiles of a plurality of secondary beams lying next to one another preferably overlap, the point of inflection of an intensity profile in each case lying within an intensity profile of an adjacent secondary beam. This results in a particularly high homogeneity of the exposure of the
• the dose of a pixel is understood to mean the amount of electromagnetic radiation with which the photosensitive material in one
• Pixel was applied at any time during the maskless writing process (exposure).
• the optical power of the primary beam is between 0.01 W and 1000W, preferably between 0.1W and 750W, more preferably between 1W and 500W, most preferably between 10W and 250W, most preferably between 20W and 50W.
• the optical power attributed to a secondary beam is then approximately the ratio between the optical power of the primary beam and the number of DMD mirrors irradiated. For example, a DMD has 1000x 1000 pixels. Accordingly, the optical performance of the
• Primary beam of 25W an optical power of 0.000025 watts on a secondary beam. Assuming an irradiation time of 20 p s per pixel, an energy of 5 * 10 10 J or 500 pJ per single secondary beam would be transferred to one pixel.
• Oversampling can increase this energy per pixel accordingly when passing through the DMD.
• the pixel energy is in particular between 10 J and 1 J, preferably between 10 - 1 2 J and 10 -2 J, more preferably between 10 - 12
• the irradiation time is in particular between 10 9 s and 1 s,
• the individual dose D is therefore, in particular, the energy with which a pixel is acted upon in a single exposure.
• the cumulative is taken under the entire dose of a pixel
• each pixel receives part of the dose from secondary rays of neighboring pixels.
• the cumulative dose specifies in particular the gray tone of a pixel.
• a mirror line is a set of mirrors of a DMD
• a mirror column is understood to be a set of mirrors of a DMD that are positioned along a second axis of the DMD reference system.
• the second axis is normal to the first axis of the DMD reference system.
• the mirror lines do not become normal or
• Mirror columns are not arranged parallel to the direction of movement.
• a mirror exposure line is understood to be a set of mirrors of a DMD that lie along a line normal to the direction of movement. If the DMD is not rotated in relation to the direction of movement, The exposure line and mirror line are identical in relation to the lateral arrangement.
• a mirror exposure column is understood to be a set of mirrors of a DMD that lie along a line parallel to the direction of movement. If the DMD is not rotated in relation to the direction of movement, the exposure slits and mirror slits would be identical in relation to the lateral arrangement.
• a mirror exposure line block is a set of mirror exposure lines that are used for the complete exposure of all
• the additional DMD mirrors can perform additional functions. In particular, they can be used as redundancy or additional ones can be used
• Mirror exposure line blocks for be formed.
• the amount of mirror exposure lines per mirror exposure line block is constant, i.e. the number of mirror exposure line blocks is an integral divisor of the number of mirror exposure lines.
• the number of gray tones is then by the number of mirror exposure lines per
• a systematic error is the deviation of the statically from the
• Sample quantity determined expected value of a parameter from true value of the population. The greater the accuracy, the smaller the value of the deviation, the smaller the systematic error.
• Precision is understood to mean the scatter of a measurement variable around the expected value of the sample quantity. The greater the precision, the smaller the spread.
• Positioning accuracy is the accuracy with which a pixel in the photosensitive material can be driven congruently through the center of a DMD mirror. This positioning accuracy is particularly due to an inclined position of the DMD
• Direction of movement between the DMD and the photosensitive material increased.
• the device according to the invention consists of a substrate holder and an optical system.
• the substrate holder has technical features known in the prior art for fixing and / or aligning and / or moving a substrate.
• the fixations are used to hold the in the device
• fixations can be
• Vacuum fixings in particular with individually controllable or interconnected vacuum paths, and / or
• electrical fixations in particular electrostatic fixations, and / or
• the fixings can be controlled electronically in particular.
• Vacuum fixation is the preferred type of fixation.
• the vacuum fixation consists preferably of several vacuum paths that emerge on the surface of the sub-holder.
• the vacuum tracks can preferably be controlled individually. In a technically preferred realizable application, some vacuum tracks are combined to form vacuum track segments that can be individually controlled, and therefore can be evacuated or flooded.
• Vacuum segment is preferably independent of the others
• Vacuum segments ie preferably from individually controllable
• Vacuum segments are preferably constructed in a ring shape. This enables a specific, radially symmetrical, in particular fixation and / or detachment of a substrate from the substrate holder to be carried out from the inside out.
• the substrate holder can preferably be actively moved relative to a fixed coordinate system.
• the position of the substrate holder is continuously tracked, measured and stored during the movement.
• the precision of the positioning is described by the confidence interval of the variance.
• the precision possesses for a three sigma
• Confidence level of 99.7% a confidence interval between 1 nm and 10 pm, preferably between 1 nm and 10 pm, more preferably between 1 nm and 10 pm, more preferably between 1 nm and 10 nm, most preferably between 1 nm and 1 nm, most most preferred between 1 nm and 5 nm.
• the optical system of the device consists in particular of at least one light source and in particular a DMD.
• Optical elements for homogenizing the primary beam are preferably located in the optical path, in particular at least or only in the path of the
• All optical elements are preferably fixedly mounted in relation to a base, so that a relative movement, at least during the exposure, only by moving the substrate by means of the Substrate holder is done. All optical elements can preferably be calibrated in six spatial directions.
• the foundation or base on which the substrate holder is moved is preferably vibration-damped. The vibration damping can take place actively and / or passively.
• the foundation is preferably a granite block. Even more preferred around an active vibration damping granite block.
• the DMD mirrors are designed as binary switching elements, which corresponds to a preferred embodiment of the invention, with which the invention can be described more easily.
• Each mirror of the DMD can be in a single state of the following two states at a certain point in time: either it reflects its part of the primary beam onto the photosensitive material or it reflects its part of the primary beam so that it does not hit the photo sensitive material ,
• the two states of a mirror are accordingly referred to as "on” (English: ON, the photosensitive material is hit) and “off” (English: OFF, the photosensitive material is not hit).
• the two binary states are accordingly spoken of more precisely. This term simplifies reading the text.
• the mirrors of a DMD can preferably only be switched all at the same time, with the choice between ON and OFF.
• the switching frequency for the simultaneous switching of all mirrors is in particular greater than 1 Hz, preferably greater than 100 Hz, more preferably greater than 1 kHz, most preferably greater than 100 kHz, most preferably greater than 1 MHz.
• an increase in the positioning accuracy is achieved in particular by tilting the DMD in relation to the relative direction of movement.
• Positioning accuracy can be achieved by using optical elements that distort the secondary beams.
• optical elements that distort the secondary beams There are other methods in the prior art for increasing the positioning accuracy, but not all of them are listed individually here. Exemplary, but not restrictive, are the benefits of increasing the
• DMDs For a simple maskless (or correct, dynamically structured) exposure system with a scanning imaging principle, a DMD with a single mirror line would be sufficient according to the invention. DMDs that are common and available on the market usually have a large number
• Mirror rows e.g. 1080 mirror rows with 1920 mirror columns each in a Full HD DMD.
• Such DMDs with more than one mirror line are preferably used according to the invention.
• the additional mirror lines are used in particular to increase the position accuracy by means of oversampling. Oversampling is described, for example, in US4700235A regarding printing technology.
• angle of rotation cc is especially with the formula n
• n is the distance between the pixel rows and m is the distance between the pixel columns between two nearest mirror centers.
• the desired dose of each pixel over several points in time is determined cumulatively.
• each individual exposure is carried out with the same
• the cumulative exposure of one of the pixels is carried out by
• the first idea according to the invention is therefore based on the idea that during a relative movement between the DMD and the photosensitive layer, a pixel that has a gray tone level n, at least n times of n different mirrors of a DMD that split along the mirror exposure are exposed. For example, if you choose a maximum
• Grayscale depth of 128, and if a pixel should get a gray tone n l 3, then 13 mirrors must be within one
• the gray tone of a single pixel can be set in a targeted manner.
• the number of gray tones that can be generated per pixel is in the first invention
• the DMD generally consists of several mirrors and
• this method can be used to generate entire patterns at the same time.
• the aspect of this method according to the invention can therefore also be summarized in such a way that a temporal averaging of similar exposure steps with different patterns is carried out with each exposure step.
• the desired dose of a pixel is generated by the fact that s a precisely adjustable dose acts on the desired pixel at each exposure time.
• a precisely adjustable dose acts on the desired pixel at each exposure time.
• the intensity of the radiation source of the primary beam is specifically changed while the DMD is over a position to be exposed.
• Pixel is then defined by the dose that arrives at the pixel at the given point in time. Since the intensity of the radiation source can be specifically set and changed, the dose can also be changed in a targeted manner.
• the method according to the invention is suitable for setting the radiation intensity of the source to a defined value at a time and for illuminating several pixels simultaneously with this dose by the resulting dose per DMD mirror in accordance with the switching state of each mirror.
• the frequency of the radiation from the radiation source can be changed or multiple radiation sources are used, each of which can generate radiation with a different frequency.
• the frequency of the radiation from a radiation source should in particular harmonize with the photosensitive material used, ie it should be able to change it chemically and / or physically as efficiently as possible.
• the grayscale can also be varied using radiation with different intensities.
• Pixel equal to 2 k , where k is the number of used
• a pixel of k-mirror exposure lines of one and only one mirror exposure line block is exposed or not exposed.
• Pixel equal to 2 k , where k is the number of used
• the first mirror exposure line can preferably receive the full dose, the two mirror exposure lines the half dose, the next mirror exposure line the fourth dose, and the kth mirror exposure line the (1/2) k dose.
• the frequency at which the intensity of the radiation source can be changed is in particular greater than 10 Hz, preferably greater than 100 Hz, more preferably greater than 1 kHz, most preferably greater than 100 kHz, most preferably greater than 1 MHz.
• a dithering algorithm is used in order to generate an, in particular averaged, dose in a pixel region which is in particular larger than a single pixel .
• the principle of the algorithm is to set the gray tones of pixels lying next to one another in such a way that there is an averaged gray tone value for the pixel area.
• the method mentioned can in particular be based on several, in the state of
• s is a relative local subsampling, the original oversampled pixels, for the purpose of
• the method according to the invention generates a pixel area that is larger than the individual pixels. Accordingly, the advantage of positioning accuracy achieved in the event of an inclination of the DMD is at least partially lost for the gray tone resolution obtained by the mathematical algorithm.
• Another important feature of the method according to the invention is a continuous (that is, at least along an exposure strip uninterrupted) relative movement between the photosensitive material and the DMD during the application of the method according to the invention.
• the methods according to the invention therefore preferably do not represent step process methods, but continuous motion methods.
• All of the methods according to the invention can also be used in classic, binary lithography in order to improve the homogeneity of the illumination and thus to improve the process stability and image quality.
• the intensity distribution of the entire DMD image is first recorded (e.g. with a CCD chip in the exposure plane or test exposures using a gray tone varnish, or several
• Test exposures can be determined in Lorm from data series.
• the methods according to the invention can in particular be used to produce the following products.
• Methods according to the invention can be used to generate a lot of optical elements, in particular lenses, in the photosensitive material.
• Fresnel, convex or concave lenses have pronounced three-dimensional shapes that can be produced with the aid of the method according to the invention.
• these optical elements are produced as part of a monolithic lens substrate (MLS).
• stamps created are in particular directly as
• Methods according to the invention are used to generate lithographic masks or at least to serve as a negative for lithographic masks.
• Methods according to the invention are used to structure a, in particular wavy and non-planar and / or homogeneous, layer of the photosensitive material using the methods according to the invention.
• the gray tones are generated in relation to the ripple so that s the ripple of the photosensitive material has no influence on the topography that develops after development. This makes it possible to expose a photosensitive material without having to remove the waviness beforehand using complicated processes and methods
• Methods of the invention are used to create a flat surface.
• each substrate has a certain ripple and / or roughness.
• a layer that is applied to such a substrate partially takes on the waviness and / or the roughness of the underlying substrate.
• a lithography according to the invention could be carried out in such a way that the wave crests of the layer were treated lithographically in such a way that after the exposure and development process, the wave crests were removed or planarized Layer takes place.
• a method according to the invention for planarization of the layer is thus available, which is not based on mechanical, but purely photolithographic methods.
• Methods according to the invention can be used to generate MEMS structures.
• FIG. 1 shows a schematic representation of an embodiment of a device according to the invention with optics and a photosensitive layer to be exposed arranged on a substrate,
• FIG. 2 shows a schematic illustration of an embodiment of a method according to the invention with several
• Figure 3 a is a schematic representation of an embodiment of the
• Apparatus according to the invention in one method step in an exposure through a radiation source with a first intensity spectrum
• Figure 3b is a schematic representation of an embodiment of the
• Apparatus according to the invention in one method step in an exposure through a radiation source with a second intensity spectrum
• FIG. 4 shows a schematic illustration of a photosensitive layer exposed with an embodiment of the invention
• Figure 5 is a schematic cross-sectional view of a section of the substrate with the photosensitive layer to be exposed.
• FIG. 1 shows a simplified schematic illustration of a set of pixels 1.
• the pixels 1 are with the following
• Simplification of the display does not show the DMD 3 itself, but its projection onto the photosensitive layer 19. For the sake of simplicity, a distinction is no longer made between the actual DMD 3 and its actual elements and their projections.
• Mirror 4
• 4 ‘, 4 ′′ of the DMD 3 are in mirror rows 9z and mirror columns 9s
• the mirror lines 9z are arranged rotated by the angle cc with respect to the direction of movement v.
• the relative direction of movement v takes place along the y axis.
• the substrate 6 on which the photosensitive material 18 is located is fixed on a substrate holder 14 and moved with it in the negative y-direction, the DMD 3 preferably being fixed statically at least during the exposure.
• the DMD 3 can be designed to be movable, this being a less preferred embodiment. Accordingly, with v the relative direction of movement between the DMD 3 and the photosensitive material 18 or
• the pixels 1 represent the positions which can be illuminated by secondary beams 16 deflected by the mirrors 4, 4 ', 4 ".
• the width of the secondary beams 16 is preferably at least as large as the mirrors 4, 4 ', 4 ".
• the secondary rays 16 have a characteristic, in particular Gaussian, intensity profile 5, 5 '.
• the characteristic intensity profile 5, 5 ' defines the intensity distribution in the photosensitive material 18 or in the respective pixel 1.
• each mirror center 4c of a mirror 4 of the DMD 3 is congruent with one of the image points 1, which - as described below - are exposed in a targeted manner with regard to their exposure profile.
• the relative movement is understood to mean that the DMD 3 and the photosensitive layer 19 to be exposed are moved relative to one another, preferably either the DMD 3 or the photosensitive layer 19 being moved while the non-moving part is statically fixed.
• the photosensitive layer 19, which is located on the substrate 6, is preferably moved actively in relation to a spatially fixed coordinate system, while the DMD 3 and all other optical elements (not shown) are moved relative to the spatially fixed
• the image point 1 is first under the mirror 4, then under the mirror 4 ′′ and finally under the mirror 4 ′′.
• one of the mirrors 4, 4 ′′, 4 “could be switched in such a way that it directs a secondary beam onto the photosensitive
• Material 18 reflects, so that the photo sensitive material 18 with a (Further) Do sis is applied to generate a gray tone G. Each exposure leads to an increase in gray tone G.
• a mirror exposure column l Os represents a column of pixels 1 running in the direction of movement v
• Mirror exposure column l Os arranged mirrors 4 can be exposed.
• FIG. 1 It can be seen in FIG. 1 that there are a total of four mirrors 4, 4 ′′, 4 ′′ on the mirror exposure column l Os, whose
• Mirror centers 4c are congruent to the mirror exposure column l Os. In this specific case, only the three mirrors 4, 4 ′′, 4 “can thus be used
• Exposure of the pixel 1 can be used during a
• the six hundred mirror exposure lines l oz can, for example and advantageously, be combined to form two hundred mirror exposure line blocks 17.
• Mirror exposure line blocks 17 are used to expose a pixel 1 with one of four gray tones G (no exposure at all, exposure with one dose, with two doses or with three doses).
• the frame in the lower right part of the exposure strip 2 symbolizes a pixel area 8, consisting of a total of nine pixels 1.
• the pixel area 8 is preferably approximately the same size as the mirror 4 of the DMD 3. By using an unrest algorithm, an averaged gray tone is set in this image area 8.
• a further, essential aspect according to the invention consists in the fact that an inclination of the optics, in particular the DMD 3, relative to the direction of movement v and / or the pixel lines 11z increases the positioning accuracy, but this in favor of producing an averaged gray tone in the Image area 8 is again at least partially abandoned.
• the resolution of the structures in the photosensitive material 1 8 cannot be greater than the resolution of the mirrors in the DMD 3.
• gray tones G are summarized as averaged gray tones of a pixel area, a very efficient gray tone lithography can be carried out.
• FIG. 2 shows a series of exposure steps of part of an exposure strip 2 with several pixels 1. The illustrated
• the first image in the series consists of part of an exposure strip 2, in which some pixels 1 of the bottom five lines have already been exposed. Each exposed pixel 1 was exposed only once, so that a gray tone value of 1 can be assigned to each exposed pixel 1.
• the gray tone values are described according to their strength by a natural number including the zero.
• Photosensitive layer 19 can expose subsequent mirrors 4 of the DMD 3 pixels 1 that have already been exposed, provided that the algorithm provides for the exposure of the respective pixel.
• the algorithm has been set so that a dithering pattern results in the pixel area 8.
• the picture series shows on the one hand the use of a dithering algorithm, on the other hand the setting of a gray tone G by multiple exposure of mirror elements connected in series.
• FIGS. 3 a and 3b show schematic representations of a
• Embodiment of the method according to the invention in which the dose which is used for the exposure of the pixels 1 is varied by changing the radiation intensity of a radiation source 12.
• a state is shown in which in turn only a mirror 4 of a DMD 3 is switched so that it exposes a pixel 1 on a photosensitive material 18.
• the radiation source 12 generates a primary beam 15, which can be influenced by optical elements 13 before it strikes the DMD 3. There, the individual mirrors 4 of the DMD 3 generate a corresponding number of individual secondary beams 16 for generating individual pixels 1.
• the intensity of the radiation source 12 influences and defines the strength of the dose, the shape of the intensity profiles 5, 5 'and thus the gray tone G. The definition can be determined empirically or by physico-chemical processes.
• the optics is the sum of the optical elements 13 and the DMD 3.
• FIG. 4 shows a gray tone gradient created from the averaged gray tones by the method according to the invention, the gradient of which decreases from left to right.
• Each pixel area comprises 8, 8 ', 8 ", 8'" nine pixels (not
• the pixel area 8 has the strongest, averaged gray tone (from the nine gray tones G of the individual pixels, not shown).
• the averaged gray tones of the pixel areas 8 ′′, 8 ′′ and 8 ′′ “decrease continuously from left to right.
• Each averaged gray tone of a pixel area 8, 8 ′′, 8 ′′, 8 ′′ ” was created using mathematical algorithms in connection with the gray tone adjustment of individual pixels 1 (not shown for the sake of clarity) according to the inventive method described above.
• FIG. 5 shows part of a cross section of a substrate 6 on which a photosensitive layer 19 consisting of a photosensitive material 18 has been deposited.
• An image point 1 is also shown, with an exposure profile depth t. It can be seen that the exposure profile depth t makes up approximately one third of the total thickness of the photosensitive layer 19.
• DMD 3 micromirror device

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• 2018
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  • 2018-06-19 EP EP18734150.8A patent/EP3811153A1/de active Pending
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• 2019
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