US3900736A - Method and apparatus for positioning a beam of charged particles - Google Patents

Method and apparatus for positioning a beam of charged particles Download PDF

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Publication number
US3900736A
US3900736A US437585A US43758574A US3900736A US 3900736 A US3900736 A US 3900736A US 437585 A US437585 A US 437585A US 43758574 A US43758574 A US 43758574A US 3900736 A US3900736 A US 3900736A
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area
actual
location
shape
predetermined
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US437585A
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Michel S Michail
Ollie C Woodard
Hannon S Yourke
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International Business Machines Corp
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International Business Machines Corp
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Priority to US437585A priority Critical patent/US3900736A/en
Priority to CA214,984A priority patent/CA1016667A/en
Priority to FR7441667A priority patent/FR2259390B1/fr
Priority to IT30791/74A priority patent/IT1027867B/it
Priority to JP49149133A priority patent/JPS5223221B2/ja
Priority to GB817/75A priority patent/GB1480561A/en
Priority to DE2502431A priority patent/DE2502431C2/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
    • H01J37/147—Arrangements for directing or deflecting the discharge along a desired path
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/304—Controlling tubes by information coming from the objects or from the beam, e.g. correction signals
    • H01J37/3045—Object or beam position registration

Definitions

  • COMPUTER 19 n is w ANALOG mum umr CONTROL PATENTEDAUB'I 4915 3,900,736
  • the size of each chip site must be limited to that of the writing field so that any beam error therein is within a certain range. Accordingly. the size of the writing fields cannot be enlarged to enable a single pattern to be written within a single writing field, which defines the maximum size of a chip site in the aforesaid Kruppa et al patent, when the pattern size exceeds the maximum field size within which the beam can be written and still have the beam error within the desired range.
  • the present invention is an improvement of the method and apparatus of the aforesaid Kruppa et 211 patent in that a single pattern can be written in more than one writing field rather than being limited to one writing field.
  • the method and apparatus of the present invention permit a semiconductor wafer to have continuous patterns larger than the field to which the beam can be applied accurately to be written therein.
  • each field which is not on the periphery of the fields of the wafer, has an overlying relation with four other adjacent fields.
  • a registration mark is disposed in the overlying area of the adjacent fields.
  • each of these registration marks While it is desired for each of these registration marks to be at a design position so that the registration marks would define a four sided rectangular or square shaped field having the registration marks at their corners, there is usually some slight deviation of each of the registration marks from its design position since the registration marks are written on the wafer within a certain tolerance. Therefore, the registration marks are normally not at their design positions but at some deviation therefrom. By ascertaining the deviation of each of thefour registration marks for a particular field from the design locations for the registration marks, the boundaries of the writing field are located.
  • the beam Since the beam is being applied in accordance with a predetermined pattern in which the field was deemed to be a perfect square or rectangle, these deviations of the registration marks for the particular field result in the field not being a perfect square or rectangle. There fore, if the beam were to be applied in accordance with the predetermined pattern, the beam may be applied beyond the boundaries defined by the registration marks and into another field if correction is not made.
  • the registration marks in the upper and lower right hand corners of the first field will be the registration marks in the upper and lower left hand corners for the next field. Therefore, these two registration marks define the common boundary between the two fields and function as reference points to which the beam is applied at the next of the adjacent fields.
  • the other boundaries of the field are similarly defined with respect to the registration marks of the other adjacent fields.
  • various digital constants can be determined and applied throughout writing of the pattern within the particular field.
  • the digital constants are utilized to correct for translation, magnification, rotation, and distortion of the beam in the X and Y directions.
  • correction voltages are applied for both the X and Y directions to a set of electrostatic field plates to shift the beam from the predetermined position to the actual deviated position in accordance with the actual field as defined by the actual location of the registration marks.
  • the beam is written within the boundaries of the field since the beam would either be compressed or extended, for example. in each line to compensate for the difference between the predetermined position and the actual position.
  • the method and apparatus of the present invention is particularly useful when it is desired to write a plurality of patterns at different levels of a chip with each level being written at a different time.
  • the present invention enables overlay accuracy between the written fields at various levels on a chip.
  • the present invention accomplishes this through ascertaining the actual location of each of the four regis tration marks of a field, as previously mentioned, and retaining these actual locationsfor reference throughout the various levels of pattern writing. If it should be necessary to use a new set of registration marks, these would be written with their actual locations determined with respect to the actual locations of the prior registration marks, which define the field.
  • the beam can always be shifted from its predetermined position to its actual deviated position irrespective of the level at which the pattern is being written to insure that the pattern at each level has an accurate overlay with the patterns at other levels of the field.
  • An object of this invention is to dynamically position a beam of charged particles at each of the positions to whichit is moved within a field on a semiconductor wafer in accordance with the boundaries of the field.
  • Another object of this invention is to provide a method and apparatus for writing a continuous pattern with a beam of charged particles in more than one field on a semiconductor'wafer with each field having a separate portion of the pattern written therein at various times.
  • a further object of this invention is to dynamically position a beam of charged particles at each of the positions to which it is moved within an area on a target in accordance with the actual boundaries of the area.
  • Still another object of this invention is to provide a method and apparatus for writing a continuous pattern with a beam of charged particles in more than one area of a target with each'area having a separate portion of the pattern written therein at different times.
  • A'stillfu'rth'er object of this invention is to provide a method and apparatus for automatically overlaying two separate patterns written within an area on a target or within a field on a semiconductor wafer with each pattern written therein at various times.
  • FIG. 1 is a schematic view showing an electron beam and the apparatus for controlling the beam.
  • FIG. 2 is a schematic block diagram of a circuit arrangement for dynamically supplying signals to shift the beam from each of its predetermined positions to the actual deviated position in accordance with the location of the registration marks of the field to which the beam is being applied.
  • FIG. 3 is a schematic diagram showing the relation between an actual field to which the beam is to be applied in conjunction with the learn corrected field to which the beam would be applied without dynamic correction for the location of the registration marks.
  • FIG. 4 is a top plan viewof a portion of a semiconductor wafer having fields to which the beam" is to be
  • FIG. 5 is an enlarged top plan view of a registration mark that identifies one corner of a field within which an electron beam can write.
  • FIG. 6 is a schematic wiring diagram showing the magnetic deflection circuit for controlling the X magnetic deflection coils.
  • FIG. '7 is a schematic wiring diagram showing the electrostatic deflection circuit for controlling the X electrostatic deflection plates.
  • an electron gun 10 for producing a beam 11 of charged particles in the well-known manner.
  • the electron beam 11 is passed through an aperture 12 in a plate 14 to shape the beam 11.
  • the beam 11 is preferably square shaped and has a size equal to the minimum line width of the pattern that is to be formed.
  • the beam 11 passes between a pair of blanking plates 16, which determine when the beam 11 is applied to the material and when the beam 11 is blanked.
  • blanking plates 16 are controlled by circuits of an analog unit 17.
  • the analog unit 17 is controlled by a digital control unit 18 in the manner more particularly shown and described in the copending patent application of Philip M. Ryan for Method And Apparatus For Controlling Movable Means Such As An Electron Beam, Ser. No. 398,734, filed Sept. 19, I973, and assigned to the same assignee as the assignee of this application.
  • the digital control unit 18 is connected to a computer 19, which is preferably an IBM 370 computer.
  • the beam 11 then passes through a circular aperture 21 in a plate 22. This controls the beam 11 so that only the charged particles passing through'the centers of the lenses (not shown) are used so that a square-shaped spot without any distortion is produced.
  • the beam 11 is next directed through magnetic deflection coils 23, 24, 25, and 26.
  • the magnetic deflection coils 23 and 24 control the deflection of the beam 11 in a horizontal or X direction while the magnetic deflection coils 25 and 26 control the deflection of the beam 11 in a vertical or Y direction. Accordingly, the coils 23-26 cooperate to move the beam 11 in a horizontal scan by appropriately deflecting the beam 11.
  • the beam 11 could be moved in a substantially raster fashion as shown and described in the aforesaid Kruppa et al patent, it is preferably moved in a back and forth scan so that the beam 11 moves in opposite directions along adjacent lines as shown and described in the aforesaid Ryan application.
  • the negative bucking sawtooth of the type shown in FIG. 3b of the aforesaid Kruppa et al patent is supplied to the coils 23 and 24 during forward scan while a positive bucking sawtooth, which is of opposite polarity to the sawtooth shown in FIG. 3b of the aforesaid Kruppa et al patent, is supplied to the coils 23 and 24 during the backward scan.
  • the beam 11 then passes between a first set of electrostatic deflection plates 27, 28, 29, and 30.
  • the electrostatic deflection plates 27 and 28 cooperate to deflect the beam in a'horizontal or X direction while the electrostatic deflection plates 29 and 30 cooperate to move the beam 11 in the vertical or Y direction.
  • the plates 27-30 are employed to provide any desired offset of the beam 11 at each of the predetermined positions or spots to which it is moved. In the aforesaid Kruppa et al patent, the plates 27-30 corrected for linearity, but these correction signals are supplied to the coils 23-26 in this application.
  • the beam 11 After passing between the electrostatic deflection plates 27-30, the beam 11 then passes between a second set of electrostatic deflection plates 31, 32,33, and 34.
  • the electrostatic deflection'plates 31 and 32 cooperate to deflect the beam 11 in the horizontal or X direction while the electrostatic deflection plates 33 and 34 cooperate to deflect the beam 11 in the vertical or Y direction.
  • the plates 31 and 32 deflect the beam 1 l in the X direction and the plates 33 and 34 deflect the beam 11 in the Y direction from each of the predetermined positions to which it is moved in accordance with its predetermined pattern so that the beam 11 is applied to its actual position based on the deviation of the area from its designed position, both shape and location, in which the beam 11 is to write.
  • the beam 11 is then applied to a target, which is supported on a table 35.
  • the table 35 is movable in the X and Y directions as more particularly shown and described in the aforesaid Kruppa et al patent.
  • the beam 11 is moved through A, B, and C cycles as shown and described in the aforesaid Kruppa et al patent.
  • the present invention is concerned with supplying signals to shift the beam 11 from each of the predetermined positions to which it is stepped to a deviated actual position, which is determined by the location of an actual field in comparison with the design field, during the B cycle when the pattern is being written.
  • the target may comprise a plurality of fields 39 which overlap each other.
  • a chip 40 may be formed within each of the fields 39 so that there is a plurality of the chips 40 on a semiconductor wafer 41 with each of the chips 40 having resist to be exposed by the beam 11.
  • the chip 40 may comprise a plurality of the fields 39 or one of the fields 39 may have a plurality of the chips 40. The following description will be with one of the chips 40 formed within each ofthe fields 39.
  • registration mark 42 (schematically shown as a cross in FIG. 4 at each of the four corners of each of the fields 39. As shown in FIG. 4, the overlapping of the adjacent fields3 9 results in the same registration mark 42 being utilized for each of four different adjacent fields 39.
  • the registration mark,42 in the lower right corner of the only complete field 39 shown in FIG. 4 also is the registration mark in the lower left corner for the field 39 to the right of the complete field 39, the upper right corner of the field below the complete field 39, and the upper left corner of the field 39 which is diagonally to the right of the completed field 39.
  • Each of the registration marks. 42 is preferably formed of a plurality of horizontally extending bars 43, preferably three in number as shown in FIG. 5, and a plurality of vertically extending bars 44, preferably equal in number to the number of the bars 43. Any other suitable arrangement of registration marks can-be employed in which there can be scan of vertical edges of the mark in the X direction and of horizontal edges of the mark in the Y direction.
  • the overlapping of the fields 39 enables writing to occur between the adjacent fields.
  • the boundary of each of the chips 40 is within the overlapping area of the field 39 of the chip 40 and is normally defined by the lines extending between the registration marks 42.
  • the design field as defined by the registration marks 42 being located at design positions 1, 2, 3, and 4 in FIG. 3, would exist, and the beam 11 would be applied thereto.
  • the design field 50 would be a perfect square or rectangle and is the learn corrected field.
  • the registration marks 42 are not located at the design positions 1, 2, 3, and 4 as shown in FIG. 3. Instead, because of these various factors, the registration marks 42 are located at positions such as positions 1, 2', 3, and 4, for example, as shown in FIG. 3. As a result, an actual field 51, which is not necessarily a perfect square or rectangle but is four sided, in which the beam 11 can write is produced by the registration marks 42 being at the positions 1, 2, 3, and 4' rather than the design positions 1, 2, 3, and 4.
  • the line between the positions 2' and 3 must be accurately defined so that the beam II will form a continuation of the same lines within the field 51 when writing in the field to the right of the field 51.
  • the line defined between the positions 2 and 3 is the boundary between the chip 40 within the field 51 and the chip 40 within the field to the right of the field 51 so that this is a common boundary between the two chips 40. It should be understood that the area of the chip 40 within which the beam 11 writes need not be the entire field as defined by the positions of the registration marks 42 but can be smaller and use the registration marks 42 as reference points.
  • the difference between the design and actual positions of each of the registration marks 42 can be defined by setting forth the difference between the design and actual positions of the mark 42 in both the X and Y directions.
  • the equations for any specific mark position are:
  • dX A+BX+CY+DXY and
  • X represents the design position of the mark in the X direction and Y represents the design position in the Y direction with dX being the distance between the design position and the actual position in the X direction and dY being the distance between the actual position and the design position in the Y direction.
  • A, B, C, D, E, F, G. and H is a digital constant which can be ascertained for the particular field within which the beam 11 is to be applied.
  • the digital constant A represents the translation of the beam in the X direction while the digital constant E represents the translation of the beam 11 in the Y direction.
  • the digital constant B represents the magnification error in the X direction.
  • the digital constant G represents the magnification error in the Y direction.
  • the digital constant C represents the rotation error of the beam 1] in the X direction
  • the digital constant F represents the rotation error of the beam 11 in the Y direction.
  • the digital constant D represents the distortion of the beam 11 in the X direction
  • the digital constant H represents the distortion of the beam 11 in the Y direction.
  • the design field 50 is shown as being a square.
  • the distance between the marks 42 at positions 1 and 2 in the design field S0 or positions 3 and 4 in the field 50 is the same and may be defined by W.
  • the height of the field 50 between the positions 1 and 4 or positions 2 and 3 is the same and may be defined as 11.
  • equations (11) to (18) are for the special case of symmetry between the four mark positions, similar equations could be generated for the general case of non-symmetry between the four positions 1, 2, 3, and 4 of the design registration marks 42 so that dX,, dX. dX dX,, dY dY dY,,, and dY can be obtained.
  • equations (3) to (6) could be written as all 1'. all ⁇ 1'- all a (1' 4/), II
  • each of the single column matrices in each of equations l9) and (20) is a vector matrix and the four collumn matrix in each of equations l9) and (20) is the system matrix.
  • equation (19) can be written as .1 1 x, 1', x31, .ix, n 1 x 1 x 1, 1,1,. (21 1 .x, 1,, 24,1, 1.x, 1) 1 X, 1', x,1', (IX,
  • the digital constants A, B, C, D, E, F, G, and H are ascertained through using the design locations of the positions 1, 2, 3, and 4 in the X and Y directions, which are known for the design field 50, along with the actual distances, as defined by dX to dX and dY to dY,, between the positions 1, 2, 3, and 4 and the positions 1, 2, 3, and 4, respectively, in the X and Y directions.
  • Each of the positions of the beam 1] in the field 50 also is defined by the magnetic deflection voltage of the beam II at the particular position.
  • the magnetic voltages for X and Y can be substituted in equation l for dX and equation (2) for dY to ascertain the deflection voltage that must be applied to the beam 1 1 when it is at any predetermined position (X, Y) such as position 5, for example, to shift the beam 11 to its corresponding actual position (X, Y) such as position 5, for example.
  • dX is the deflection voltage to be applied for the X direction to shift the beam 11 from its predetermined position X to its actual position X
  • dY is the deflection voltage to be applied to shift the beam 11 in the Y direction from its predetermined position Y to its actual position Y.
  • the substitution of the X and Y magnetic deflection voltages in equations l and (2) enables determination of dX and dY for any position in the writing pattern. This enables the corrections to be correlated to the magnetic deflection voltages.
  • the voltage, which is obtained by solving equation l for dX, is the deflection voltage applied to the elec trostatic deflection plates 31 and 32, and the deflection voltage. which is obtained by solving equation (2) for dY, is supplied to the electrostatic deflection plates 33 and 34.
  • the deflection voltages at each of the predetermined positions causes a shift of the beam 11 to dynamically correct the deflection of the beam 11 at each of the predetermined positions to which it is stepped so that the beam 1 l is moved to the actual deviated position whereby the predetermined pattern is written within the actual field 51 rather than the design field 50 for which the pattern was programmed in the computer 19.
  • the correction voltage (dX) is supplied to the electrostatic deflection plates 31 and 32 for the X direction and the correction voltage dY is supplied to the electrostatic deflection plates 33 and 34 for the Y direction.
  • the circuit of FIG. 2 is employed. This enables dynamic correction of the beam 11 as it is stepped to each of the predetermined positions in accordance with the pattern to be written so that the beam 11 is not applied to the predetermined position to which it is stepped by the magnetic coils 2326 but is shifted to the actual deviated position.
  • the beam 11 can be on or off for the entire time that it is at a position or on for only a portion of the time.
  • the X deflection voltage is supplied from the analog unit 17 through a line 55 while the Y deflection voltage is supplied from the analog unit 17 through a line 56.
  • the X deflection voltage on the line 55 is correlated to the deflection current applied to the magnetic deflection coils 23 and 24 for the X direction at the predetermined position
  • the Y deflection voltage on the line 56 is correlated to the deflection current applied to the magnetic deflection coils v 25 and 26 for the Y direction at the predetermined position.
  • the lines 55 and 56 are connected to an analog multiplier 57, which has the product of the X and Y deflection voltages its output and supplied to each of a pair of multiplying digital to analog converters (MDAC) 58 and 59.
  • MDAC multiplying digital to analog converters
  • the multiplying digital to analog converter 58 also has an input from the digital control unit 18 with this input being the digital constant D as defined by an eight bit word supplied from the digital control unit 18 to the multiplying digital to analog converter 58.
  • the output of the multiplying digital to analog converter 58 is DXY, which corrects for distortion and trapezoidal errors in the X direction and is supplied as one of the inputs to an operational amplifier 60.
  • the operational amplifier is a summing amplifier for all of its four inputs.
  • the multiplying digital to analog converter 59 also has an input from the digital control unit I8. This input is the digital constant H and is defined by an eight bit word from the digital control unit 18.
  • the output of the multiplying digital to analog converter 59 is the product of its inputs of H and XY.
  • the output of HXY which corrects for distortion and trapezoidal error in the Y direction, is supplied as one of the four inputs to an operational amplifier 61 in which all of its four inputs are summed.
  • the other inputs to the amplifier 60 are from a digital to analog converter (DAC) 62, and multiplying digital to analog converters (MDAC) 63 and 64.
  • the other inputs to the amplifier 61 are from a digital to analog converter (DAC) 65 and multiplying digital to analog converters (MDAC) 66 and 67.
  • the input to the digital to analog converter 62 is the digital constant A. This input is a bit word from the digital control unit 18. Thus, the output of the digital to analog converter 62 to the amplifier 60 is A, which corrects for translation in the X direction.
  • the multiplying digital to analog converter63 has a first input of the X deflection voltage from the line 55.
  • a second input to the multiplying digital to analog converter 63 is the digital constant B, which is supplied from the digital control unit 18 as an eight bit word.
  • the output of the multiplying digital to analog converter 63 to the amplifier 60 is the product of the two inputs so that its output is BX. which corrects for magnification in the X directionv
  • the multiplying digital to analog converter 64 has a first input of the Y deflection voltage from the line 56.
  • the multiplying digital to analog converter 64 has the digital constant C as its second input, which is supplied as a ten bit word from the digital control unit 18 to the multiplying digital to analog converter 64. Accordingly, the output of the multiplying digital to analog converter 64 to the amplifier 60 is CY, which corrects for rotation in the X direction.
  • the four inputs which are summed by the amplifier 60 to which they are supplied, comprise A, BX, CY, and DXY. These inputs are what define dX in equation (1.1) so that the output of the amplifier 60 is the deflection voltage required to be supplied to the electrostatic deflection plates 31 and 32 to shift the beam 11 from its predetermined position to the actual deviated position in the X direction.
  • the output of the summing amplifier 60 is amplified by an amplifier 68 prior to being supplied to the electrostatic deflection r I amplifier 61 is E, which corrects for translation in the Y direction.
  • the multiplying digital to analog converter 66 has a first input of the X deflection voltage from the line 55.
  • the other input to the multiplying digital to analog converter 66 is the digital constant F, which is supplied from the digital control unit 18 as a 10 bit word.
  • the output of the multiplying digital to analog converter 66 to the amplifier 61 is the product of its inputs so that its output is FX, which corrects for rotation in the Y direction.
  • the multiplying digital to analog converter 67 has a first input of the Y deflection voltage from the line 56.
  • the multiplying digital to analog converter 67 has the digital constant G as its second input, which is supplied from the digital control unit 18 as an eight bit word.
  • the output of the multiplying digital to analog converter 67 to the amplifier 61 is GY, which is the product of its inputs and corrects for magnification in the Y direction.
  • the inputs to the amplifier 61 are E, FX,
  • the beam 11 is applied to the actual deviated position rather than the predetermined position as it is stepped from one position to another in accordance with its predetermined pattern, which it is writing within the chip 40 located within the boundaries of the actual field 51.
  • the beam 11 determines the location of the registration marks 42 for the initial field, then the patterns can be written continuously throughout the remainder of the wafer 41 without any mechanical corrections with respect to the actual location of each of the fields all corrections will be made through the circuit of FIG. 2.
  • the location of the registration marks 42 for each of the actual fields 51 must be made before any writing of the this field occurs. g I r 7 It should be understood that the beam 11 attempts to' locate the registration marks 42 at the design p'ositions, but these do not occur because of the various factors previously mentioned.
  • the beam 11 requires the use of a focus grid and a calibration grid in the same manner as described in the aforesaid Kruppa et al patent.
  • a focus grid and a calibration grid in the same manner as described in the aforesaid Kruppa et al patent.
  • One suitable example of these grids is the focus and calibration grids of the aforesaid Kruppa et al patent.
  • each of the registration marks 42 has been described as having the bars 43 and 44 formed as depressions, it should be understood that the bars 43 and 44 could be formed otherwiseas long as they produced a signal when the beam 11 passed thereover. For exam-' ple, each of the bars 43 and 44 could be a raised portion.
  • the magnetic deflection coils 2326 cooperate to move the beam in a horizontal or X scan by appropriately deflecting the beam 11.
  • the circuit for controlling the X magnetic deflection coils 23 and 24 is shown in FIG. 6.
  • This circuit includes both positive constant current sources 70, 71, and 72 and negative constant current sources 73, 74, and 75.
  • the constant current sources -75 controlled by logic control signals from the digital control unit 18 and derived from an X counter, which is part of the digital control unit 18, charge a capacitor 77.
  • Each of the positive and negative constant current sources is not the same value so that the charge of the capacitor 77 may be different depending on which of pattern in the current sources 7075 is used.
  • the charge for the capacitor 77 for the different constant current sources 70-75 produces different voltage ramps, which have slopes depending upon the value of the turned on current source. The length of the ramp is dependent upon the time that the current source is activated. It should be understood that more than one of the current sources 70-75 can be turned on simultaneously to produce a variety of slopes.
  • the positive current source 70 is turned on by a signal on a line 78 from the digital control unit 18 in accordance with the X counter only during the B cycle.
  • the positive current source 71 is turned on by a signal on a line 79 from the digital control unit 18 in accordance with the X counter only during the A cycle.
  • the negative constant current source 74 is also turned on only during the A cycle by a signal on a line 80 from the digital control unit 18 in accordance with the X counter.
  • the negative constant current source 73 is turned on by a signal on a line 81 from the digital control unit 18 in accordance with the X counter only during the B cycle.
  • the digital control unit 18, in accordance with the X counter, may turn on the positive current source 72 by a signal on a line 82 or the negative current source 75 by a signal on a line 83. Only one of the current sources 72 and 75 is turned on at one time.
  • the current sources 72 and 75 are used primarily during the C cycle to move the beam left or right as required for focusing. They may be used at other times to probe the beam movement as desired.
  • the positive constant current source 70 is used to move the beam 1 1 in the X scans in one direction.
  • the negative current source 73 is used to move the beam 11 in the X scans in the other direction.
  • the capacitor 77 is connected to the magnetic deflection coils 23 and 24 through an operational amplifier 84, corrector circuitry 85, a summing point 86, and a driver amplifier 87.
  • the driver amplifier 87 and the summing point 86 function as a summing amplifier.
  • the amplifier 84 forms an integrator along with the capacitor 77 and isolates the current sources 70-75 from the driver amplifier 87, which converts the voltage to current, and from the corrector circuitry 85.
  • the corrector circuitry 85 compensates for nonlinearity of the beam 11 to a degree. Thus, the corrector circuitry 85 modifies the voltage ramps so that the beam deflection approaches linearity.
  • DAC digital to analog converter
  • One suitable example of the bit digital to an alog converter 88 is sold as model No. DAC-HI 10B by Datel Systems Inc.
  • the 10 bit digital to analog converter 88 is connected to the digital control unit 18 to receive correction words therefrom, and its output is supplied to the negative input of the amplifier 89 through a resistor 90.
  • a capacitor 91 cooperates with the resistor 90 to integrate the output of the 10 bit digital to analog converter 88.
  • the output of the amplifier 89 is supplied as one of the inputs to the summing point 86 to complete the correction for non-linearity.
  • the digital control unit 18 is connected through a line 92 and a diode 93 to an FET 94.
  • the diode 93 and the FET 94 together form an analog switch.
  • the FET 94 is turned on to cause a reset of the correction for non-linearity from the output of the amplifier 89 sincethe beam 11 moves in the opposite direction after the retrace gate.
  • the voltage developed across a sense resistor 94' by the current returning from the deflection coils 23 and 24 is fed to a comparing amplifier 95 and compared with a reference signal supplied from a 16 bit digital to analog converter (DAC) 96, which is controlled by a 16 bit word from the digital control unit 18, through a line 97.
  • DAC digital to analog converter
  • the comparing amplifier 95 amplifies the difference between the voltage across the sense resistor 94 and the reference voltage and supplies it as an error voltage to an analog switch 98.
  • a signal through a line 99 from the digital control unit 18 in accordance with the X counter closes the analog switch 98 causing the error voltage to supply current to the integrator, which comprises the capacitor 77 and the amplifier 84, through a resistor 100.
  • the integrator which comprises the capacitor 77 and the amplifier 84
  • This charges the capacitor 77 in the proper direction to cause the deflection voltage across the sense resistor 94' to approach the reference voltage.
  • Current is supplied until the error voltage is reduced to zero at which time the deflection voltage is equal to the reference voltage. This insures that the beam 11 is ready for scanning in the opposite X direction. It should be understood that the signal on the line 99 is removed at the end of retrace time.
  • the speed at which the beam 11 scans in each of the X directions during the various cycles is controlled. If the positive constant current source is considered to be +I and the negative constant current source 73 is considered to be I, then the source 71 is l/IO I, the source 72 is -l l/660 I, the source 74 is 1/10 I, and the source is l/660 I.
  • the line 55 which is connected to the analog multiplier 57 in FIG. 2, is connected between the coil 24 and the sense resistor 94. This enables the deflection voltage to be obtained as the beam 11 moves in the X direction.
  • FIG. 7 there is shown an electrostatic deflection circuit for controlling the X electrostatic deflection plates 27 and 28.
  • the Y electrostatic deflection plates 29 and 30 would be controlled by a similar type of circuit.
  • the electrostatic circuit has an input from the digital control unit 18 in accordance with the X counter through a line to a clamping NPN transistor 111, which resets the charge on a capacitor 112.
  • the capacitor 112 is connected to a positive constant current source 113.
  • the capacitor 112 and the constant current source 113 produce a positive bucking sawtooth as an output.
  • the capacitor 112 is connected through a high impedance amplifier 114 to a summing point 115.
  • the summing point 115 is connected to a push-pull amplifier 116, which is connected to the X electrostatic deflection plates 27 and 28.
  • the push-pull amplifier 116 inverts the signal from the amplifier 114 so that the signal, which is produced by the amplifier l 14, is a negative sawtooth at the output of the pushpull amplifier 116.
  • a second circuit produces a positive bucking sawtooth at the output of the push-pull amplifier 116 to cause the beam 1 l to step from right to left in the X direction.
  • This circuit includes an input from the digital control unit 18 in accordance with the X counter through a line 120 to a clamping PNP transistor 121. which resets the charge on a capacitor 122.
  • the capacitor 122 is connected to a negative constant current source 123.
  • the capacitor 122 and the constant current source 123 produce a negative sawtooth as an output.
  • the capacitor 122 is connected through a high impedance amplifier 124 to the summing point 115 from which the negative sawtooth is supplied to the pushpull amplifier 116, which inverts the input to produce a positive bucking sawtooth as its output. It should be understood that the amplifiers 114 and 124 isolate the capacitors H2 and 122, respectively, from the pushpull amplifier 116.
  • the electrostatic deflection circuit also is utilized to produce offset of the beam in the X direction in either the direction in which the beam 11 is moving or the opposite direction.
  • the offset signal is supplied to the summing point 115 from a four bit digital to analog converter 125, which receives its input from the digital control unit 18 (see FIG. 1) in the manner more particularly shown and described in the aforesaid Ryan application.
  • the line 110 or the line 120 receives a signal to cause the bucking sawtooth to be applied for a period of four lines to the push-pull amplifier 116.
  • This bucking sawtooth is supplied due to signals from the digital control unit 18 on the line 110 or 120.
  • the line 110 or 120 is activated by the digital control unit 18 in accordance with the X counter such that the negative and positive bucking sawtooths are operative for a period of every other line of scan in accordance with the direction in which the beam 11 is moving.
  • the present invention has been described as exposing a resist, it should be understood that exposure may be made of any other phenomenon. For example, there could be exposure of silicon dioxide that is to have its etch rating enhanced While the present invention has described the apparatus as being employed to expose the resist on the chips of a semi-conductor wafer, it should be understood that the present invention may be employed anywhere it is desired to correct or change the position of a beam, which moves in any deflection-fashion, without affecting the history of the beam in its deflection movement. Thus, for example. the present invention could be readily employed to produce engineer drawings on a cathode-ray tube or to control an electron beam welder or cutter. v
  • the target has been described as being a semiconductor wafer, for example, it should be understood that the target could be other materials.
  • the target could be a material in which a mask could be formed by the beam, for example.
  • the beam has been described as being moved in a line by line scan, it should be understood that such is not a requisite for satisfactory operation.
  • the beam can be moved in any fashion from one position to another within the field in which the pattern is written.
  • the beam could be continuously moved with continous dynamic correction occurring.
  • An advantage of this invention is that a single pattern can be written in more than one field. Another advantage of this invention is that it improves overlay accuracy. A further advantage of this invention is that it eliminates the need for mechanical correction for variations due to placing the wafer under the beam.
  • a method of positioning a beam of charged particles comprising:
  • the beam is moved in the predetermined path by simultaneously deflecting the beam in orthogonal directions through the use of a separate deflection voltage for each of the orthogonal directions; and obtaining the dynamic electronic compensation at each of the predetermined positions for the deviation of the actual position from the predetermined position by modifying the orthogonal deflection voltages for deflecting the beam to the predetermined position in each of the orthogonal directions in accordance with the location and shape of the actual area relative to the location and shape of the design area to obtain the compensating deflection of the beam in each of the orthogonal directions.
  • the location and shape of the area of the target is ascertained by scanning each of the four corners of the area of the target separately with the beam.
  • a method of writing a continuous pattern in more than one contiguous four-sided area of a target with a beam of charged particles including:
  • the method according to claim 13 including applying the beam to each of the first and second actual areas after formation of another level of the wafer to form another continuous pattern at the another level.
  • An apparatus for controlling the movement of a beam of charged particles comprising:
  • said shifting means includes:
  • said producing means includes:
  • first means to produce a first signal in accordance with the deviation of the actual position from the corresponding predetermined position in a first direction
  • said first means of said producing means produces the first signal dependent on the deflection signals supplied to said beam moving means to move the beam in each of the first and second directions to the predetermined position; and said second means of said producing means produces the second signal dependent on the deflection signals supplied to said beam moving means to move the beam in each of the first and second directions to the predetermined position.
  • the apparatus according to claim 15 including:
  • said beam moving means moving the beam to a plu rality of predetermined positions within the design area at each of the different levels of the wafer in accordance with the pattern for the particular level after each level is formed;
  • said storing means supplying the stored information to said beam moving means for the plurality of predetermined positions within the design area to which the beam is to be moved in accordance with the pattern for the particular level;
  • said shifting means shifting the beam to each of the actual positions within the actual area from the corresponding predetermined position within the design area.
  • An apparatus for writing a continuous pattern with a beam of charged particles in more than one contiguous four-sided area of a target including:
  • first means to control said moving means to move the beam to ascertain the actual location and shape of a first four-sided area relative to the location and shape of a first design four-sided area; said first means including means to control said moving means to move the beam over the first design area in accordance with a predetermined pattern;
  • said first means controlling said moving means to move the beam to ascertain the actual location and shape of a second area relative to the location and shape of a second design area with the second actual area having a common boundary with the first actual area;
  • control means of said first means controlling said moving means to move the beam over the second design area in accordance with the predetermined pattern
  • said first means includes means to scan each of the four corners of each of the areas of the'target to be located with the beam so to ascertain the location and shape of each of the areas of the target to be located in accordance with the location of the four corners of the area of the target to be located.
  • a method of positioning a beam of charged particles comprising:

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Beam Exposure (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
US437585A 1974-01-28 1974-01-28 Method and apparatus for positioning a beam of charged particles Expired - Lifetime US3900736A (en)

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US437585A US3900736A (en) 1974-01-28 1974-01-28 Method and apparatus for positioning a beam of charged particles
CA214,984A CA1016667A (en) 1974-01-28 1974-11-29 Method and apparatus for positioning a beam of charged particles
FR7441667A FR2259390B1 (ja) 1974-01-28 1974-12-05
IT30791/74A IT1027867B (it) 1974-01-28 1974-12-20 Sistema ed apparecchiatura per posizionare un fascio di particel le caricate
JP49149133A JPS5223221B2 (ja) 1974-01-28 1974-12-27
GB817/75A GB1480561A (en) 1974-01-28 1975-01-08 Controlling the movement of a beam of charged particles
DE2502431A DE2502431C2 (de) 1974-01-28 1975-01-22 Verfahren für die dynamische Korrektur der Ablenkung eines Elektronenstrahls

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JP (1) JPS5223221B2 (ja)
CA (1) CA1016667A (ja)
DE (1) DE2502431C2 (ja)
FR (1) FR2259390B1 (ja)
GB (1) GB1480561A (ja)
IT (1) IT1027867B (ja)

Cited By (16)

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US4105890A (en) * 1976-05-03 1978-08-08 Movchan Boris Alexeevich Device for electron-beam heating of materials
US4137459A (en) * 1978-02-13 1979-01-30 International Business Machines Corporation Method and apparatus for applying focus correction in E-beam system
US4181860A (en) * 1977-01-31 1980-01-01 Vlsi Technology Research Association Radiant beam exposure method
EP0049872A2 (en) * 1980-10-15 1982-04-21 Kabushiki Kaisha Toshiba Electron beam exposure system
WO1982003126A1 (en) * 1981-03-03 1982-09-16 Veeco Instr Inc Reregistration system for a charged particle beam exposure system
US4390788A (en) * 1980-03-05 1983-06-28 Hitachi, Ltd. Electron beam patterning method and apparatus with correction of deflection distortion
US4528452A (en) * 1982-12-09 1985-07-09 Electron Beam Corporation Alignment and detection system for electron image projectors
US4818885A (en) * 1987-06-30 1989-04-04 International Business Machines Corporation Electron beam writing method and system using large range deflection in combination with a continuously moving table
US5126530A (en) * 1989-11-29 1992-06-30 Mercedes-Benz Ag Method for producing hollow gas exchange valves for reciprocating engines
US5194349A (en) * 1992-02-07 1993-03-16 Midwest Research Institute Erasable, multiple level logic optical memory disk
US5301124A (en) * 1991-08-09 1994-04-05 International Business Machines Corporation Registration of patterns formed of multiple fields
US5304441A (en) * 1992-12-31 1994-04-19 International Business Machines Corporation Method of optimizing exposure of photoresist by patterning as a function of thermal modeling
US5428552A (en) * 1991-10-08 1995-06-27 International Business Machines Corporation Data compaction techniques for generation of a complex image
US5838013A (en) * 1996-11-13 1998-11-17 International Business Machines Corporation Method for monitoring resist charging in a charged particle system
WO2002045124A2 (en) * 2000-11-30 2002-06-06 Applied Materials, Inc. Measurement device with remote adjustment of electron beam stigmation by using mosfet ohmic properties and isolation devices
WO2004051696A2 (en) * 2002-11-29 2004-06-17 Oregon Health & Science University One dimensional beam blanker array

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JPS5360162A (en) * 1976-11-10 1978-05-30 Toshiba Corp Electron beam irradiation device
JPS5367365A (en) * 1976-11-29 1978-06-15 Nippon Telegr & Teleph Corp <Ntt> Correcting method for beam position
JPS54108581A (en) * 1978-02-13 1979-08-25 Jeol Ltd Electron-beam exposure device
JPS5552223A (en) * 1978-10-13 1980-04-16 Nippon Telegr & Teleph Corp <Ntt> Exposure method in electronic beam exposure device
DE2937136A1 (de) * 1979-09-13 1981-04-02 Siemens AG, 1000 Berlin und 8000 München Verfahren und vorrichtung zur schnellen ablenkung eines korpuskularstrahls
JPS5740927A (en) * 1980-08-26 1982-03-06 Fujitsu Ltd Exposing method of electron beam
GB2238630B (en) * 1989-11-29 1993-12-22 Sundstrand Corp Control systems

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US3644700A (en) * 1969-12-15 1972-02-22 Ibm Method and apparatus for controlling an electron beam
US3651303A (en) * 1968-10-18 1972-03-21 Siemens Ag Method and apparatus for treating objects in a corpuscular ray device

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US3651303A (en) * 1968-10-18 1972-03-21 Siemens Ag Method and apparatus for treating objects in a corpuscular ray device
US3644700A (en) * 1969-12-15 1972-02-22 Ibm Method and apparatus for controlling an electron beam

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4105890A (en) * 1976-05-03 1978-08-08 Movchan Boris Alexeevich Device for electron-beam heating of materials
US4181860A (en) * 1977-01-31 1980-01-01 Vlsi Technology Research Association Radiant beam exposure method
US4137459A (en) * 1978-02-13 1979-01-30 International Business Machines Corporation Method and apparatus for applying focus correction in E-beam system
US4390788A (en) * 1980-03-05 1983-06-28 Hitachi, Ltd. Electron beam patterning method and apparatus with correction of deflection distortion
EP0049872A2 (en) * 1980-10-15 1982-04-21 Kabushiki Kaisha Toshiba Electron beam exposure system
EP0049872A3 (en) * 1980-10-15 1982-04-28 Tokyo Shibaura Denki Kabushiki Kaisha Electron beam exposure system
US4543512A (en) * 1980-10-15 1985-09-24 Tokyo Shibaura Denki Kabushiki Kaisha Electron beam exposure system
WO1982003126A1 (en) * 1981-03-03 1982-09-16 Veeco Instr Inc Reregistration system for a charged particle beam exposure system
US4385238A (en) * 1981-03-03 1983-05-24 Veeco Instruments Incorporated Reregistration system for a charged particle beam exposure system
US4528452A (en) * 1982-12-09 1985-07-09 Electron Beam Corporation Alignment and detection system for electron image projectors
US4818885A (en) * 1987-06-30 1989-04-04 International Business Machines Corporation Electron beam writing method and system using large range deflection in combination with a continuously moving table
US5126530A (en) * 1989-11-29 1992-06-30 Mercedes-Benz Ag Method for producing hollow gas exchange valves for reciprocating engines
US5301124A (en) * 1991-08-09 1994-04-05 International Business Machines Corporation Registration of patterns formed of multiple fields
US5428552A (en) * 1991-10-08 1995-06-27 International Business Machines Corporation Data compaction techniques for generation of a complex image
US5194349A (en) * 1992-02-07 1993-03-16 Midwest Research Institute Erasable, multiple level logic optical memory disk
US5304441A (en) * 1992-12-31 1994-04-19 International Business Machines Corporation Method of optimizing exposure of photoresist by patterning as a function of thermal modeling
US5838013A (en) * 1996-11-13 1998-11-17 International Business Machines Corporation Method for monitoring resist charging in a charged particle system
WO2002045124A2 (en) * 2000-11-30 2002-06-06 Applied Materials, Inc. Measurement device with remote adjustment of electron beam stigmation by using mosfet ohmic properties and isolation devices
WO2002045124A3 (en) * 2000-11-30 2003-02-13 Applied Materials Inc Measurement device with remote adjustment of electron beam stigmation by using mosfet ohmic properties and isolation devices
WO2004051696A2 (en) * 2002-11-29 2004-06-17 Oregon Health & Science University One dimensional beam blanker array
WO2004051696A3 (en) * 2002-11-29 2004-10-14 Univ Oregon Health & Science One dimensional beam blanker array

Also Published As

Publication number Publication date
FR2259390A1 (ja) 1975-08-22
DE2502431A1 (de) 1975-07-31
JPS5223221B2 (ja) 1977-06-22
GB1480561A (en) 1977-07-20
CA1016667A (en) 1977-08-30
IT1027867B (it) 1978-12-20
JPS50105381A (ja) 1975-08-20
FR2259390B1 (ja) 1976-10-22
DE2502431C2 (de) 1984-08-30

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