Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
  • G01N21/9501—Semiconductor wafers
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/8806—Specially adapted optical and illumination features
• • 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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
  • H01L22/10—Measuring as part of the manufacturing process
  • H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/8806—Specially adapted optical and illumination features
  • G01N2021/8845—Multiple wavelengths of illumination or detection
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
  • G01N21/956—Inspecting patterns on the surface of objects
  • G01N2021/95676—Masks, reticles, shadow masks
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/06—Illumination; Optics
  • G01N2201/061—Sources
  • G01N2201/06113—Coherent sources; lasers
  • G01N2201/0612—Laser diodes

Definitions

• the invention generally relates to the field of wafer and reticle inspection and metrology. More particularly the present invention relates to the light sources of such inspection and metrology tools.
• circuit designers provide circuit pattern data, which describes a particular integrated circuit (IC) design, to a reticle production system, or reticle writer.
• IC integrated circuit
• optical inspection and metrology systems are used within the semiconductor industry to detect defects or characterize structures on a semiconductor reticle or wafer.
• One type of tool is an optical inspection or metrology system.
• one or more incident beams are directed towards the semiconductor wafer or reticle and a reflected and/or scattered beam is then detected.
• the detected beam is used to then generate a detected electrical signal or an image, and such signal or image is then analyzed to determine whether defects are present on the wafer or reticle or characterize features on the sample under test.
• Various light source mechanisms can be used with optical inspection and metrology tools.
• One example is an arc lamp based light source.
• Another example is a laser sustained plasma light source.
• Both an arc lamp and plasma based light source tend to produce a significant amount of out-of-band radiation, which leads to poor power conversion efficiency. Additionally, these light sources require complex thermal heat management mechanisms for the out-of-band radiation.
• the plasma based light source also has limits on power brightness scalability.
• an optical apparatus for performing inspection or metrology of a semiconductor device.
• the apparatus includes a plurality of laser diode arrays that are configurable to provide an incident beam having different wavelength ranges.
• the apparatus also includes optics for directing the incident beam towards the sample, a detector for generating an output signal or image based on an output beam emanating from the sample in response to the incident beam, and optics for directing the output beam towards the detector.
• the apparatus further includes a controller for configuring the laser diode arrays to provide the incident beam at the different wavelength ranges and detecting defects or characterizing a feature of the sample based on the output signal or image.
• the laser diode arrays include deep UV (ultra-violet) and UV continuous wave diode lasers. In one aspect, the laser diode arrays further include VIS (visible) and NIR (near infrared) continuous wave diode lasers. In yet a further aspect, the laser diode arrays include a plurality of two dimensional (2D) stacks of diode bars that can be selectively activated to result in the incident beam having different wavelength ranges that together form a broadband range.
• 2D two dimensional
• the controller is configured to activate one or more laser diode arrays so that the incident beam has a specific wavelength range that is selected from the different wavelength ranges and configured to deactivate other one or more of the laser diode arrays so that the incident beam does not include any wavelengths that are not within the specific wavelength range.
• the apparatus includes beam shaping optics for receiving output light from the activated one or more laser diode arrays and forming different illumination profiles in the incident beam.
• the apparatus includes coupling optics for receiving and combining output light from the activated one or more laser diode arrays.
• the coupling optics comprises a spatial coupler or polarization coupler to combine output light having a same wavelength so as to achieve a higher net power than a power of individual diodes or diode bars of the laser diode arrays and a wavelength coupler for combining output light having different wavelength ranges.
• the laser diode arrays include a plurality of two dimensional (2D) stacks of diode bars, wherein the stacks have different wavelength ranges.
• the wavelength ranges of the stacks together cover a range between about 190 nm and about 1000 nm.
• the wavelength ranges of the stacks together include wavelengths in the deep UV, UV, VIS, and NIR.
• a first set of one or more stacks is formed from deep UV or UV based laser diodes; a second set of one or more stacks is formed from VIS based laser diodes; and a third set of one or more stacks is formed from deep NIR based laser diodes.
• each stack has a wavelength range width that is between about 15 to 80 nm.
• Each laser diode of each diode bar can provide about 1 watt or more of power. In one example, each stack provides about 200 watts or more of power. In another implementation, the diode bars of each 2D stack have a same wavelength range as its corresponding 2D stack.
• the invention pertains to a method of generating a light source in a semiconductor inspection tool.
• One or more laser diode arrays are selected and activated to generate light at a selected inspection application's specified wavelength range while preventing other one or more laser diode arrays from generating light outside the specified wavelength range.
• Light from the activated one or more laser diode arrays is coupled together to form an incident beam.
• the incident beam is directed to a wafer or reticle, and the selected inspection application is performed based on light detected from the wafer or reticle in response to the incident beam.
• the operations for selecting and activating one or more laser diode arrays, coupling light, directing the incident beam, and performing the selected inspection application are repeated for a plurality of sequentially selected inspection applications having different specified wavelength ranges.
• Figure 1 is a diagrammatic representation of an illumination source arrangement having configurable diode arrays in accordance with one embodiment of the present invention.
• Figure 2A is a diagrammatic representation of forming a 2D stack from individual emitter diodes in accordance with a specific implementation of the present invention.
• Figure 2B is a perspective view of an edge-emitting laser diode bar in accordance with a specific implementation of the present invention.
• Figure 2C is a perspective view of an edge-emitting laser diode stack in accordance with a specific implementation of the present invention.
• Figure 3A is a diagrammatic representation of spatial coupling optics for coupling the outputs of configurable diode arrays in accordance with one embodiment of the present invention.
• Figure 3B is a diagrammatic representation of a polarization coupling optics arrangement for coupling the outputs of configurable diode arrays in accordance with one embodiment of the present invention.
• Figure 3C is a diagrammatic representation of a wavelength coupling optics arrangement for coupling the outputs of configurable diode arrays in accordance with a first implementation.
• Figure 3D is a diagrammatic representation of a wavelength coupling optics arrangement for coupling the outputs of configurable diode arrays in accordance with a second implementation.
• Figure 4 illustrates a homogenizer in the form of an optical fiber having a single flat facet.
• Figure 5 is a flow chart illustrating a procedure for light source generation and inspection/metrology in accordance with one embodiment of the present invention.
• Figures 6A through 6C represent different illumination profiles that can be produced at the pupil plane by embodiments of the present invention.
• Figure 7 is a diagrammatic representation of an inspection system, in which embodiments of illumination source module with configurable diode laser arrays, may be integrated in accordance with a specific implementation of the present invention.
• an illumination source having configurable incoherent laser diode arrays for use in an optical inspection tool.
• the illumination source includes laser diode arrays that are configurable to cover specific ranges of wavelengths as needed in the particular inspection application.
• the laser diode arrays provide wavelength widths that are selectively obtained from the Deep-UV (ultra-violet), UV, VIS (visible), and NIR (near-infrared) range.
• Figure 1 is a diagrammatic representation of an illumination source arrangement 101 having configurable diode arrays in accordance with one embodiment of the present invention. As shown, the illumination source arrangement 101 includes a plurality of illumination sources 102.
• each illumination source 102 is in the form of a plurality of configurable 2D stacks of laser emitter diodes (e.g., Stacks 1-n) although each illumination source could simply be in the form of a ID array of emitter diodes.
• the illumination source arrangement 101 may also include beam shaping optics 104 for manipulating the profile of one or more of the beams output by the active diodes and beam coupling optics 105 for coupling the beams output from the active illumination sources together.
• the beam shaping optics 104 are arranged adjacent to the illumination sources so as to directly receive and shape one or more of the beams that are output from the illumination sources.
• the beam coupling optics 105 may be arranged adjacent to the illumination sources so as to directly receive and couple the beams output from the illumination sources prior to the coupled beam being received by the beam shaping optics 104.
• the illumination source arrangement 101 may also include a homogenizer 106 for receiving the coupled, shaped resulting beam that is output from the beam coupling optics 105 and the beam shaping optics 104.
• the coupled and/or shaped incident beam passes through a first end of 106a the homogenizer 106 and may be output through a second end 106b of such homogenizer 106 to provide incident light for a particular inspection or metrology system as described further below.
• the illustrated illumination source module 101 is described as comprising shaping optics 104, beam coupling optics 105, and homogenizer 106, it is understood that one or more of these components could be integrated in other modules of an optical inspection or metrology tool.
• the illumination source module 101 may not include a homogenizer so that the output of the beam shaping optics 105 is produced onto the input of an optical tool's homogenizer or another suitable optical component of such optical system.
• one or more illumination sources 102 may be selectively turned on to output one or more beams that can be coupled onto a first fiber end 106a.
• one or more other illumination source 102 may be turned off so as to be prevented from outputting a beam that is coupled and/or shaped onto the first fiber end 106a to produce an incident beam.
• Each illumination source may be selectively activated simultaneously, sequentially, or in any suitable order.
• FIG. 2A is a diagrammatic representation of a 2D diode stack 206 in accordance with a specific implementation of the present invention.
• a ID diode bar 204 is formed from individual emitter diodes (e.g., 202, 202a, 202b), and a plurality of ID diode bars (e.g., 204a, 204b, 204c, and 204d) are used to form 2D diode stack 206.
• continuous wave emitters may be used to form 2D diode stacks.
• Each emitter diode may be in the form of an edge type emitter so that the output is propagated along the wafer surface and out a cleaved side edge of the diode.
• the diode material can be altered so as to generate different wavelength ranges for the diode output.
• Each 2D stack can be formed from diode bars that have the same or different wavelength characteristics.
• the different stacks, and optionally the different diode bars of one or more stacks can cover different wavelength widths or ranges.
• the stacks can then selectively cover a wide range of wavelengths for various applications. For instance, if all of the diode stacks were activated, they would together produce light having a wavelength range of about 190 to 1000 nm, or even as low as 100 nm.
• a first set of bars or stacks may be formed from different DUV-UV based diodes; a second set of bars or stacks can be formed from different VIS based diodes; while a third set of bars or stacks can be formed from different NIR based diodes.
• Deep UV and UV based diodes in wavelength ranges of about 220 nm to about 330 nm have been developed by numerous companies and institutes, such as RIKEN Advanced Science Institute of Japan. These Deep UV and UV based diodes from RIKEN have a maximum output power is 33mW for a 270nm DUV-LED, by way of specific example. For diodes with wavelength shorter than 260nm, the output powers are 15mW and 5mW for 247nm and 237nm DUV-LEDs, respectively.
• VIS and NIR based diodes, bars, and stacks having power in the 10's of mW's are available from Oclaro of San Jose, CA.
• stack 1 has a wavelength range of X+5 nm to X+10 nm
• stack 2 has a wavelength range of X+15 nm to X+20 nm. If X equals 190 nm and portions of the range between 190 nm and 1000 nm are to be selectively covered, the remaining stacks each have different ranges, up to X+810 nm for stack n.
• Each stack of this arrangement can be formed from ID diode bars that each has the same wavelength range as its stack. A stack's individual bars may have the same wavelength range to achieve a particular power requirement.
• a stack's individual bars may have different wavelength widths if the power requirements are met by a single bar.
• a first bar 204a of stack 206 ( Figure 2) has a first width of X+5 nm to X+10 nm
• a second bar 204b of stack 206 has a wavelength range of X+15 nm to X+20 nm
• a third bar 204c of stack 206 has a first width of X+20 nm to X+25 nm, and the remaining bars of this stack 206, as well as other stacks, can have different widths, up to X+810 nm if the same example maximum width of 190 nm to 1000 nm is used.
• Individual diodes or ID diode bars may have as low as a 5-10 nm wide bandwidth and a power range between about 10's of mW's and 100's of mW's.
• each diode provides 1W (Watt) or more of power so that a 2D stack having up to 200W can be achieved by arranging up to 200 diodes in the bars of each stack.
• Multiple 200W stacks can be coupled together to form a broadband incoherent laser based light source in one inspection application, which can be very attractive for bright field tools as an alternate for laser sustained plasma sources that can only achieve kW's of power. Integrating such emitters into 2-D stacks will make it possible to get this high power output in a small wavelength spread ( ⁇ 3nm FWHM) that can be coupled into a 1 mm diameter delivery fiber with 0.24 NA, by way of example.
• ⁇ 3nm FWHM small wavelength spread
• each selectable subset of diodes can have a 15-80 nm wavelength width, which can be selectively activated and combined into wider widths.
• These arrangements allow particular wavelengths to be turned on or off on demand, depending on the particular layer being inspected and the kind of defect.
• the laser power of the activated light sources can also be directly modulated, depending on the wafer type, resulting in an efficient light source with reduced illuminator thermal management concerns. That is, complex thermal management mechanisms are not needed.
• each laser diode includes a current-carrying p-n or p-i-n semiconductor junction, in which holes recombine to release energy as photons.
• the photons can be emitted perpendicular to the semiconductor surface (surface emitting diode) or emitted from a cleaved edge (edge-emitting diode).
• Figure 2B is a perspective view of a laser diode bar 250 having a plurality of waveguides (e.g., 252a and 252b) for outputting light (e.g., 256) for each diode at a cleaved edge 254 of the diode bar.
• Each stack may then be formed from ID arrays of edge emitter diodes as shown in Figure 2C.
• the stack 270 may be formed from alternating ID diode bars (e.g., 272a and 272b) and heat sink layers (e.g., 274a and 274b).
• Each ID diode bar can be configurable to edge-emit light from waveguides (e.g., 276a and 276b).
• each stack may be fabricated by cleaving ID laser arrays from a wafer. Each ID laser array is attached to a thin heat sink layer. The sets of ID array and heat sink layer are then attached together to form alternating array and heat sink layers. The width and height of each stack can be selected based on the particular aperture, delivery fiber width, and NA of the inspection system.
• the output of two or more of the active ID or 2D diode arrays can be coupled to any suitable type of coupler, such as a spatial coupler, polarization coupler, a wavelength coupler, or any combination thereof.
• the first two coupling types can be used to increase the net output from a laser at a particular wavelength, while the wavelength coupling type may be used to achieve a more broadband source with multiple wavelengths that are simultaneously coupled into the delivery path.
• Figures 3A-3C illustrate these different ways to combine the output of 2D diode stacks.
• Figure 3A is a diagrammatic representation of a spatial coupling optics arrangement 300 for coupling the outputs of configurable diode arrays in accordance with one embodiment of the present invention.
• the output of stackl 302a and stack2 302b are both received by spatial coupling optics 304, which is configured to spatially combine the two beams so that such beams are delivered onto a portion of the delivery path, e.g., fiber 306.
• spatial coupling optics 304 directs the output of stackl 302a to the top half of optical fiber 306 and directs the output of stack2 302b to the lower half of optical fiber 306.
• the fiber mixes the received light together.
• the spatial coupling optics may take the form of individual fibers that are fed into a larger light pipe or fiber. The large fiber mixes the light.
• any set of activated one or more stacks may be spatially coupled onto the delivery path.
• Figure 3B is a diagrammatic representation of a polarization coupling optics arrangement 372 for coupling the outputs of configurable diode arrays in accordance with one embodiment of the present invention.
• an S polarizer 356 is arranged to receive the output from a first stack (not shown) and output S polarization 354a.
• a polarization coupler 352 is then arranged to receive the P polarization output 354b from a second stack (not shown) and couple the S and P polarization outputs together.
• FIG. 3C is a diagrammatic representation of a wavelength coupling optics arrangement 370 for coupling the outputs of configurable diode arrays in accordance with a first implementation.
• the wavelength coupling optics are formed from dichroic mirrors that each transmit a first wavelength and reflect a second wavelength.
• output 374a from a first diode array
• output 374b from a second array
• the two outputs having wavlength_l and wavelength_2 are combined by mirror 372a.
• a second mirror 372b is then arranged to receive and transmit the combined beams and reflect a third output 374c (from a third diode array) having a third wavelength_3 so that the three outputs 374a ⁇ c having three wavelengths_l ⁇ 3 are combined together.
• Any number of mirrors may be successively arranged to combine any number of wavelength outputs from different diode arrays.
• the mirrors are configured to transmit and reflect the corresponding wavelength ranges of the received diode bar or stack outputs.
• Figure 3D is a diagrammatic representation of a wavelength coupling optics arrangement 370 for coupling the outputs of configurable diode arrays in accordance with a second implementation.
• a diffraction grating coupler 394 receives the output from stack 1 302a and stack2 302b via spatial coupler 396 at different angles and combines the received light into one beam, which is then received onto the delivery path, e.g., fiber 306. Finer grained wavelength widths for each diode array can be achieved with diffraction couplers.
• the coupled output may be received by a homogenizer that takes the form of one or more of the following components: an optical fiber having one or more faceted edges, micro-lens or micro-prism arrays that are combined with or without light pipes, etc.
• Figure 4 illustrates a homogenizer 400 in the form of an optical fiber having a single flat facet 402. Alternatively, the optical fiber could have multiple faceted edges.
• Figure 5 is a flow chart illustrating a procedure 500 for light source generation and inspection (or metrology) in accordance with one embodiment of the present invention. Initially, a first inspection application may be selected from a plurality of different inspection applications having different wavelength range specifications in operation 502. For instance, a deep UV inspection may be selected.
• One or more stacks (or bars) of emitter diodes may then be selected to generate light at the selected inspection's specified wavelength range without generating light outside the specified wavelength range in operation 504. For instance, only stacks (or bars) that are configured to emit deep UV are activated, while other stacks having VIS or NIR wavelength ranges are kept off or turned off.
• FIG. 6A through 6C represent different illumination profiles that can be produced at the pupil plane of the optical tool using light source embodiments of the present invention.
• the incident beam cross section at the pupil plane is represented by the dark sections.
• other types of illuminations profiles may be generated with the present invention.
• Figure 6A shows pupil plane 600 with an annular illumination profile for the beam. That is, only an annular portion 602 of the incident beam is generated at the pupil 600, while portions 604 and 606 of the incident beam are not.
• Figure 6B illustrates pupil plane 650 with a quadrapole illumination profile for the incident beam. That is, only quadrapole portions 652a through 652d of the incident beam are generated at the pupil 650, while portion 654 of the incident beam is not.
• Figure 6C illustrates pupil plane 660 with a dipole illumination profile for the incident beam. That is, only dipole portions 662a and 662b of the incident beam are generated at the pupil 650, while portion 664 of the incident beam is not.
• output from different wavelength width stacks (or bars) may be directed to different portions of the pupil area so as to result in different angles of incidence.
• each of the quadrapole portions of Figure 6B or the dipole portions of Figure 6C may be arranged to receive a stack (or bar) output beam having a different wavelength range.
• the light that is output by the active stacks (or bars), and possibly shaped, may then be coupled together in operation 508.
• a spatial, polarization, and/or wavelength coupler is arranged in the path of light output by two or more stacks (or bars). This coupling can also be arranged to work in conjunction with any shaping optics so as to achieve different stack (or bar) outputs being directed to different portions of a particular the illumination profiles.
• the coupled light may then be optionally directed through a fiber, which homogenizes the coupled light, in operation 510.
• the coupled (and possibly homogenized) light may then be directed to the sample under test in the form of a resulting incident beam and the currently selected inspection application is performed based on the resulting incident beam in operation 512. For instance, light emanating from the sample in response to the incident light is detected and analyzed to determine characteristics of the sample, such as a semiconductor wafer or reticle.
• Certain embodiments of the present invention provide customizable light source activation and generation to a beam coupler that outputs a single beam having a broad enough or "just right" wavelength range.
• This customizable light source can meet a diverse number of light source needs for different inspection or metrology applications at relatively high power levels.
• the use of multiple illuminations diode array sources allows efficient delivery of high brightness illumination to the sample. Lasers with different wavelengths can be efficiently combined. This arrangement is especially suited for dark field inspection, where an increase in light efficiency is highly desired to detect increasingly smaller surface anomalies. Additionally, different imaging and inspection modes (such as bright field and dark field inspection modes) may be readily provided simply by selectively lighting different fibers.
• FIG. 7 is a diagrammatic representation of an inspection or metrology system 100, in which embodiments of illumination source module 101 with configurable diode laser arrays, may be integrated in accordance with a specific implementation of the present invention.
• the system 100 includes the illumination source arrangement 101 of Figure 1, which includes 2D diode array stacks 102 that are each configurable to be turned on (active) or off (inactive).
• the system 100 also includes a controller 110 for causing selected ones of the illumination sources 102 to be turned on or off.
• the incident beam may pass from the homogenizer 106 through a number of lenses 108, which serve to relay the beam(s) towards a sample 116. These lenses 108 may provide any suitable beam manipulation function on the incident beam, such as collimating, converging, expanding, reducing, etc.
• the incident beam may then be received by beam splitter 112 which then reflects the incident beam through objective lens 114, which focuses the incident beam onto sample 116 at one or more incident angles. For instance, the second homogenizer end 106b is imaged onto the back focal plane 118 of the objective lens 114.
• the homogenizer 106 may take the form of a fiber 106 and be coupled with a fiber modulator (not shown), which operates to substantially eliminate the speckle noise which may be present in the incident beam to thereby produce a more uniform, incoherent illumination.
• the fiber modulator may be a piezoelectric modulator which operates to stretch the homogenizer fiber so as to change the phase difference between the modes inside the fiber to therefore reduce the spatial coherence to produce a speckle free illumination.
• the system may alternatively or additionally include rotating diffuser to reduce speckle.
• a rotating diffuser also has low light efficiency and may only be used for applications which do not require high light efficiency, such as bright field inspection.
• the inspection system also includes any suitable lens arrangements for directing the output light towards a detector.
• the output light pass through beam splitter 112, Fourier plane relay lens 120, imaging aperture 122, and zoom lens 124.
• the Fourier plane relay lens generally relays the Fourier plane of the sample to the imaging aperture 122.
• the imaging aperture 122 may be configured to block portions of the output beam.
• the aperture 122 may be configured to pass all of output light within the objective numerical aperture in a bright field inspection mode, and configured to pass only the scattered light from the sample during a dark field inspection mode.
• a filter may also be placed at the imaging aperture 122 to block higher orders of the output beam so as to filter periodic structures from the detected signal.
• the output beam may then pass through zoom lens 124, which serves to magnify the image of the sample 116.
• the output beam then impinges upon detector 126.
• Suitable sensors include charged coupled devices (CCD), CCD arrays, time delay integration (TDI) sensors, TDI sensor arrays, photomultiplier tubes (PMT), and other sensors.
• CCD charged coupled devices
• TDI time delay integration
• PMT photomultiplier tubes
• optical elements would illuminate the sample and capture the reflected image.
• the controller 110 may be any suitable combination of software and hardware and is generally configured to control various components of the inspection system 100. For instance, the controller may control selective activation of the illumination sources 102, fiber modulator settings, the imaging aperture 122 settings, etc. The controller 110 may also receive the image or signal generated by the detector 126 and be configured to analyze the resulting image or signal to determine whether defects are present on the sample, characterize defects present on the sample, or otherwise characterize the sample by determining sample parameters.
• Example sample parameters that can be determined based on one or more detected signals or images include critical dimension (CD) , film thickness, metal gate recess, high k recess, side wall angle, step height, pitch walking, trench and contact profile, overlay, material properties (e.g., material composition, refractive index, stress on critical films, including ultra-thin diffusion layers, ultra-thin gate oxides, advanced photoresists, 193nm ARC layers, ultra-thin multi-layer stacks, CVD layers, and advance high-k metal gate (HKMG), ultra-thin decoupled plasma nitridation (DPN) process layers, stress on noncritical films, including inter-dielectrics, photoresists, bottom anti-reflective coatings, thick oxides and nitrides, and back end of line layers), semiconductor manufacturing process parameters (e.g. focus and dose for scanners, etch rate for etching tools), etc.
• CD critical dimension
• material properties e.g., material composition, refractive index, stress on critical
• the second end of 106b of the homogenizer 106 may be preferably positioned such that the pupil plane of the objective lens is imaged at the second end 106b. That is, the second homogenizer ends 106b is positioned within the illumination pupil, which is the conjugate plane of the objective back focal plane 118.
• the second homogenizer end 106b may be arranged to transmit any particular shape (e.g., produced by the beam shaper optics 105) so as to illuminate a particular one- or two- dimensional area of the sample 116 at one or more incident angles.
• the controller 110 may be configured (e.g., with programming instructions) to provide a user interface (e.g., on a computer screen) for displaying resultant test images and other inspection characteristics.
• the controller 110 may also include one or more input devices (e.g., a keyboard, mouse, joystick) for providing user input, such as selecting wavelength ranges of incident light.
• the controller 110 is configured to carry out light source activation and inspection techniques.
• the controller 110 typically has one or more processors coupled to input/output ports, and one or more memories via appropriate buses or other communication mechanisms.
• Such information and program instructions may be implemented on a specially configured computer system
• such a system includes program instructions / computer code for performing various operations described herein that can be stored on a computer readable media.
• machine-readable media include, but are not limited to, magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROM disks; magneto-optical media such as optical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory devices (ROM) and random access memory (RAM).
• Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter.
• the inspection or measurement tool may be any of a number of suitable and known imaging or metrology tools arranged for resolving the critical aspects of features of a reticle or wafer.
• an inspection or measurement tool may be adapted for bright field imaging microscopy, darkfield imaging microscopy, full sky imaging microscopy, phase contrast microscopy, polarization contrast microscopy, and coherence probe microscopy.
• single and multiple image methods may be used in order to capture images of the target. These methods include, for example, single grab, double grab, single grab coherence probe microscopy (CPM) and double grab CPM methods.
• Non-imaging optical methods such as scatterometry, may be contemplated.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• General Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Pathology (AREA)
• Immunology (AREA)
• Analytical Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
• Preparing Plates And Mask In Photomechanical Process (AREA)
• Testing Or Measuring Of Semiconductors Or The Like (AREA)
• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Priority Applications (5)

Applications Claiming Priority (4)

Publications (1)

Family

ID=49774195

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (22)

Citations (5)

Family Cites Families (36)

• 2013
  • 2013-06-21 US US13/924,216 patent/US8896827B2/en active Active
  • 2013-06-26 JP JP2015520466A patent/JP6282643B2/ja active Active
  • 2013-06-26 KR KR1020197007979A patent/KR102091987B1/ko active Active
  • 2013-06-26 WO PCT/US2013/047901 patent/WO2014004679A1/en not_active Ceased
  • 2013-06-26 KR KR1020157001970A patent/KR101961900B1/ko active Active
• 2014
  • 2014-10-23 US US14/521,977 patent/US9110037B2/en active Active
  • 2014-12-23 IL IL236401A patent/IL236401B/en active IP Right Grant
• 2016
  • 2016-07-17 IL IL246806A patent/IL246806B/en active IP Right Grant
• 2018
  • 2018-01-24 JP JP2018009830A patent/JP2018119963A/ja active Pending
• 2019
  • 2019-11-28 JP JP2019215516A patent/JP6932174B2/ja active Active

Patent Citations (5)

Also Published As

Similar Documents

Legal Events