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
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
  • G03F1/82—Auxiliary processes, e.g. cleaning or inspecting
  • G03F1/84—Inspecting
• • 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
  • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
  • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
  • G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
  • G03F9/7007—Alignment other than original with workpiece
• • 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
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/38—Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
  • G03F1/44—Testing or measuring features, e.g. grid patterns, focus monitors, sawtooth scales or notched scales
• • 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
  • G03F7/70691—Handling of masks or workpieces
  • G03F7/70716—Stages
• • 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
  • G03F7/70691—Handling of masks or workpieces
  • G03F7/70775—Position control, e.g. interferometers or encoders for determining the stage position
• • 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
  • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
  • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
  • G03F9/7073—Alignment marks and their environment
  • G03F9/7084—Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels
• • 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
  • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
  • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
  • G03F9/7088—Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection
• • 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
  • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
  • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
  • G03F9/7092—Signal processing
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/60—Analysis of geometric attributes

Definitions

• the invention relates to a method for measuring the position of structures on a mask surface, in which the mask is stored in an image-evaluating coordinate measuring device on a measuring table that can be measured interferometrically, perpendicular to the optical axis of an imaging measuring system, and a mask coordinate system assigned to the mask is relatively aligned via alignment marks is aligned to a measuring device coordinate system and the target position of the structures in the mask coordinate system is predetermined
• a measuring device for carrying out such a method is described in the lecture manisk ⁇ pt “Pattern Placement Metrology for Mask Making, Dr C Blasmg, Semicon Geneva, Education Program, issued on 31 3 1998, with its basic elements.
• the measuring device is used in particular for quality control of masks for semiconductor production
• the quality of the mask is becoming increasingly critical in chip production.
• the specifications for the position of the structures (patterns) from one mask to another are becoming ever narrower.
• the measuring device described in the lecture manuscript can position the structures relative to defined alignment marks that the mask Define coordinate system, measure with an accuracy of typically better than 10 nm With the help of these alignment marks, the masks in the stepper can be aligned for the projection onto wafer surfaces.
• the steppers only have a certain area around which the mask can be moved and rotated for physical alignment.
• centrality With specifications becoming ever tighter on all components, the position of the structures relative to the outer edge of the mask is becoming an important quality feature of the mask.
• the position of the structures relative to the outer edges is referred to as "centrality” or “pattern centrality”.
• the mask is usually applied at three points in the lithography device (e.g. e-beam or laser lithography) in order to obtain a reproduced position.
• lithography device e.g. e-beam or laser lithography
• Two outer edges are defined with the three points, it being assumed that these are at right angles to one another. These two edges form a reference for the pattern created by the structures.
• the invention was therefore based on the object of specifying a measuring method with which the “pattern centrality” can be determined with greater accuracy, increased speed and with a reduced risk of damage
• This object is achieved according to the invention with a method of the type mentioned at the outset in that, in addition to the actual position of the structures in the mask coordinate system, the position of at least two outer edges of the mask which are perpendicular to one another is also measured in the mask coordinate system Outer edge in one coordinate axis is determined from the value of the edge position measured by image evaluation and in the other coordinate axis is determined by the current measuring table position. If two position values are determined for one outer edge and at least one position value for the other outer edge, two reference angles can be assumed, assuming the outer edges are at right angles to each other for determining the "centrality" can also advantageously be measured the position of the other edges, so that a check of the tolerances in the mask plate dimensions is possible and the alignment of the structures in the mask sheet he can be determined in relation to the true mask center
• an image of the outer edge of the mask can be stored in the measuring device and an edge position to be measured can be set in an automatic search run of the measuring table.
• the position of the outer edge is expediently measured uses imaging optics with a low aperture. If the measuring table surface is then designed to be reflective for the imaging rays of the measuring device at least in the area of the outer edges of the mask, the edge is illuminated in the reflected light and a sufficient light intensity reaches the measuring system.
• selected structure elements can be provided on the mask, the position of which is determined in the mask coordinate system and relative to the outer edges of the mask.
• the position of all measured structures can also be relative to the Outer edges are determined without special "centrality marks" being provided.
• the distance to the outer edges of the mask can be determined both for the selected structural elements and for the other measured structures.
• Fig. 2 shows a mask with two centrality marks
• Fig. 3 shows a typical design of the mask edge in cross section
• Fig. 4 shows a typical image of a mask edge.
• FIG. 1 shows an example of a mask layout.
• the mask plate shown contains the mask structures (reticle) generated in a lithography system. Alignment marks are applied in the free area. Two outer edges of the mask plate should be at right angles to each other. These edges are at three points. The dashed lines form the reference for the pattern centrality.
• FIG. 2 shows a mask plate with separately applied centrality marks. The distances to the two outer edges serving as reference are indicated by arrows
• edges 3 shows a cross section of a mask plate in the edge region.
• the edges are typically chamfered, the specified distance A usually being able to vary between 0.2 and 0.6 mm
• the mask is loaded onto the measuring table in the coordinate measuring system.
• An alignment is then first carried out, with which the mask is aligned with the coordinate system of the measuring device and the mask coordinate system is defined.
• the outer edges of the mask are measured
• the measuring table is moved to the position at which the edge is to be measured.
• the background of the mask should reflect well at this point, so that sufficient light from this background reaches the image-evaluating camera of the measuring device via imaging optics with a small aperture
• Such an image is shown
• the area outside the mask can be seen as a bright area
• the edge itself is definitely very dark, because due to the bevel, the incident light rays are reflected out of the aperture area of the imaging lens
• the mask surface then reflects light back into the lens
• the brightness depends on the mask type. Due to the typical brightness distribution on the outer edge of the mask plate, this image can also be saved and used for image recognition in an automatic search for the measuring table. If the table has its predefined or automatically found one
• the exact position of the edge is measured.
• the edge measurement is carried out using an image analysis method within the measurement window shown. The accuracy of the measurement depends on the resolution of the image recording system (CCD camera).
• CCD camera image recording system
• the position of the centrality marks is measured. For example, two opposite edges of the mark are measured and the center line is determined. The intersection of two perpendicular center lines determines the position
• the values determined for the edge positions and the positions of the measured centrality structures are also stored in a measurement data file and are therefore available for further evaluations. However, a separate data file can also be set up for the centrality evaluation
• the further evaluation can be carried out customer-specifically.
• the evaluation can consist, among other things, of calculating the distances between the structures relative to the edges advantageous if the position of all outer edges is known, in particular the outer dimensions of the mask plate can also be checked.
• the described method not only extends the area of application of the measuring device known per se. This also enables a new design of the mask structures, because with higher occupancy of the mask area with structures, centrality marks can be inserted at any point or selected structures from the regular mask structure can also be defined as centrality marks, which are used as such with conventional measurement methods would not be evaluable.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Geometry (AREA)
• Computer Vision & Pattern Recognition (AREA)
• Theoretical Computer Science (AREA)
• Signal Processing (AREA)
• Multimedia (AREA)
• Preparing Plates And Mask In Photomechanical Process (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=7865274

Family Applications (1)

Country Status (7)

Families Citing this family (12)

Family Cites Families (14)

• 1998
  • 1998-04-21 DE DE19817714A patent/DE19817714C5/de not_active Expired - Lifetime
• 1999
  • 1999-02-22 US US09/253,547 patent/US6226087B1/en not_active Expired - Lifetime
  • 1999-03-03 WO PCT/DE1999/000566 patent/WO1999054785A1/de active IP Right Grant
  • 1999-03-03 EP EP99917765A patent/EP1080393A1/de not_active Withdrawn
  • 1999-03-03 KR KR1020007011643A patent/KR20010042869A/ko active IP Right Grant
  • 1999-03-03 JP JP2000545071A patent/JP3488428B2/ja not_active Expired - Fee Related
  • 1999-03-29 TW TW088104917A patent/TW385359B/zh not_active IP Right Cessation

Non-Patent Citations (1)

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