JP5077656B2 - Pattern data processing method and system, and exposure method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern data processing method in which production efficiency of a mask pattern is improved, and parameters of a real exposure machine can be taken into consideration as required. <P>SOLUTION: A pattern data processing system is equipped with: a parameter input unit 62 acquiring parameters relating to an optical image and a resist image of a real exposure machine; simulation units 64, 65 obtaining an optical image and a resist image of a test pattern by simulation using the parameters; a data input unit 66 acquiring data of a resist image formed from the test pattern by using the real exposure machine; and a circuit design system 70 designing a reticle pattern by using values of parameters when a shape error between two resist images is within a predetermined allowable range. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a technique for processing a mask pattern transferred onto a substrate in a lithography process. Furthermore, the present invention relates to an exposure technique for transferring a mask pattern created by a predetermined mask pattern processing technique onto a substrate.

  For example, in a lithography process for manufacturing a device (electronic device, microdevice) such as a semiconductor integrated circuit or a liquid crystal display element, a pattern formed on a mask such as a reticle or photomask is used as a substrate via an optical system. In order to transfer to each shot area of a wafer (or glass plate, etc.) coated with a resist, a batch exposure type projection exposure apparatus such as a stepper or a scanning exposure type projection exposure apparatus such as a scanning stepper (scanner), etc. An exposure apparatus is used.

In order to create a mask pattern used in this type of exposure apparatus, conventionally, after designing the initial shape of the mask pattern based on the device pattern, the numerical aperture of the optical system of the exposure apparatus, the exposure wavelength, and the illumination optics A parameter consisting of the coherence factor (σ value) of the system was read, and a projection image when the mask pattern (initial shape) was transferred was calculated using this parameter. And when the shape of the projection image calculated in this way is different from the device pattern, a predetermined correction pattern is added to the initial shape of the mask pattern (see, for example, Patent Document 1).
JP-A-8-82915

  In the conventional mask pattern creation method, the mask pattern is designed so that the projected image when the mask pattern is transferred using the above parameters approaches the device pattern. However, an actual exposure apparatus has many more parameters besides the above parameters. Therefore, when a mask pattern is designed based only on the projection image calculated using the above parameters, and exposure is performed with an actual exposure apparatus using this mask pattern, the resulting device pattern and the target shape An error exceeding the allowable range was likely to occur in the meantime. When such an error occurs, it is necessary to return to the mask pattern design process again, and there is a problem in that the mask pattern creation efficiency is reduced.

  Further, in the conventional mask pattern creation method, the value of the parameter is a constant value that does not change. However, some of these parameters have different values for each type of exposure apparatus or for each number of exposure apparatus. Therefore, it is preferable to optimize the mask pattern creation method for each model or number of exposure apparatus that performs exposure of the mask pattern.

However, there are cases where a mask pattern to be exposed in a certain exposure apparatus does not necessarily have a pattern shape optimized for the exposure apparatus. In such a case, the mask pattern is exposed by exposure. It is preferable to take some measures on the exposure apparatus side so as to obtain a desired device pattern.
SUMMARY OF THE INVENTION In view of such problems, the present invention has an object to provide a mask pattern creation technique that takes into account the parameters of an exposure apparatus that actually performs exposure of a mask pattern as necessary, while increasing the efficiency of mask pattern creation. And

  It is another object of the present invention to provide an exposure technique capable of obtaining a desired device pattern using a mask pattern created using parameters of another exposure apparatus, for example.

The pattern data processing method according to the present invention is a pattern data processing method for processing mask pattern design data, using a first parameter of an actual exposure machine (EX) that uses a mask on which a mask pattern based on the design data is formed. , A first step (step 103) for obtaining light intensity information of the test pattern (45A to 45C) by the actual exposure machine by simulation, a second parameter relating to the photosensitive material on which an image of the mask pattern is formed, and the photosensitive material Using the light intensity information obtained by the actual exposure machine obtained in the first step, the second step (step 104) for obtaining information on the image of the photosensitive material by simulation, and the simulation obtained in the second step The information of the photosensitive material image by the sensor and the test using the actual exposure machine A third step (step 106) for obtaining a shape error between the image of the photosensitive material and the image of the actual photosensitive material by the simulation based on the information of the image of the actual photosensitive material formed on the photosensitive material. ) And a fourth step (steps 108 to 108) for changing at least one of the first parameter and the second parameter in the simulation so that the shape error obtained in the third step falls within a predetermined allowable range. 111), and a fifth process (steps 121 to 127) for designing the mask pattern using the values of the first parameter and the second parameter when the shape error falls within a predetermined allowable range. , Has.

The pattern data processing system according to the present invention uses a first parameter of an actual exposure machine that uses a mask on which a mask pattern based on the design data is formed in the pattern data processing system for processing the design data of the mask pattern. First simulation means (64) for obtaining light intensity information of the test pattern (45A to 45C) by the actual exposure machine by simulation, second parameters relating to the photosensitive material on which the image of the mask pattern is formed, and the first simulation The second simulation means (65) for obtaining information of the image of the photosensitive material by simulation using the light intensity information obtained by the actual exposure machine and the image of the photosensitive material obtained by the second simulation means. Information and its actual dew The shape error between the image of the photosensitive material and the actual image of the photosensitive material by the simulation is based on the information of the image of the actual photosensitive material formed on the photosensitive material. The comparison means (68) to be obtained, the first parameter used by the first simulation means and the second simulation means, and the first parameter so that the shape error obtained by the comparison means falls within a predetermined allowable range. The change means (61) for changing at least one of the two parameters, and the values of the first and second parameters when the shape error obtained by the comparison means falls within a predetermined allowable range, And a mask pattern design means (70B) for designing a mask pattern.

The exposure method according to the present invention is an exposure method for exposing a substrate with exposure light via a pattern and an optical system (PL), and the pattern is a mask pattern created by the pattern data processing method of the present invention. Sometimes, based on the value of the first parameter used in the fifth step, the numerical aperture of the optical system, the wavefront aberration of the optical system, the coherence factor of the illumination optical system that illuminates the pattern, the exposure light A parameter including at least one of the center wavelength and the wavelength width of the exposure light is adjusted, and after adjusting the parameter, the substrate is exposed through the pattern with the exposure light.

An exposure apparatus according to the present invention is an exposure apparatus that exposes a substrate with exposure light via a pattern and an optical system (PL), and illuminates the numerical aperture of the optical system, the wavefront aberration of the optical system, and the pattern. coherence factor, the center wavelength of the exposure light, and at least one comprises a parameter adjusting means for adjusting (31) the parameters, pattern data of the pattern by the present invention a wavelength width of the exposure light of the illumination optical system (20) to When the mask pattern is created by the processing system, the parameter adjusting means adjusts at least one parameter based on the value of the first parameter used by the mask pattern designing means .

  According to the pattern data processing method or system of the present invention, in order to design a mask pattern by comparing a test pattern simulation image with an actual exposure machine image, the simulation pattern image and the exposure apparatus are actually used. It is possible to reduce an error from an image formed by using it. Therefore, it is possible to reduce the number of times the design of the mask pattern is repeated by trial and error, and it is possible to increase the efficiency of mask pattern creation.

  Further, according to the exposure method or the exposure apparatus of the present invention, when using a mask pattern in an actual exposure apparatus, the exposure apparatus is adjusted by adjusting the parameter value of the exposure apparatus to the parameter value acquired at the time of creating the mask pattern. A state optimal for the mask pattern can be obtained, and a desired device pattern corresponding to the mask pattern can be obtained.

Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing a reticle pattern creation system 60 as a pattern data processing system comprising one or a plurality of computers of this example, and the plurality of blocks constituting the reticle pattern creation system 60 are software of a computer. The function to be performed. It should be noted that at least a part of the plurality of blocks may be configured by hardware. In FIG. 1, a reticle pattern creation system 60 includes a model setting system 70A and a circuit design system 70B.

  The model setting system 70A includes a control unit 61 that controls the overall operation of the system and a parameter input unit 62. The parameter input unit 62 includes a tool parameter (TP) that is a parameter that defines the exposure performance of the exposure apparatus (actual exposure machine), an empirical parameter (EP) that is a parameter that defines the photosensitive material on which the reticle pattern is exposed, Information such as the shape of the test pattern for simulation and the like is input via an input device (not shown) or a communication line (e-mail, Internet, etc.). The exposure apparatus is an apparatus that is scheduled to use the reticle pattern created by the reticle pattern creation system 60 of this example. Information such as input parameters is recorded in the parameter file 63. An example of the tool parameter TP in this example is the following TPi (i = 1 to 12).

[Table 1] (Tool parameter TP)
TP1) Numerical aperture (NA) of projection optical system
TP2) Coherence factor of illumination optical system (sigma value or, in the case of annular illumination, includes the annular ratio)
TP3) Exposure wavelength and wavelength width (including full width at half maximum or E95 (spectrum width where 95% of energy in the laser spectrum is concentrated))
TP4) Temperature of the liquid supplied between the projection optical system and the wafer (substrate) during immersion exposure TP5) Wavefront aberration of the projection optical system TP6) Apodization: light intensity distribution of the image of the point light source TP7) Polarization aberration (example) As prescribed by Jones Matrix)
TP8) Polarization state (defined by Stokes parameter as an example)
TP9) Pupilgram of secondary light source: For example, the amount of deviation of the intensity distribution of four decentered secondary light sources during quadrupole illumination from the ideal distribution (rectangular distribution) TP10) Thermal aberration: Projection Aberration caused by irradiation heat of exposure light in optical system TP11) MSD (Moving Standard Deviation): Amount of positional deviation due to relative vibration between reticle stage (mask stage) and wafer stage (substrate stage) TP12) Flare: mainly local Flare

Of these tool parameters TP, those that can be adjusted or corrected to some extent in the exposure apparatus are TP1 to TP5.
Examples of empirical parameters EP include the type of resist (photoresist) as a photosensitive material, the sensitivity to exposure light, the sensitivity when developing in the development process, the use conditions (temperature, etc.) in the case of a chemically amplified resist, PEB (Post Exposure Bake) baking conditions (temperature, time, etc.).

  Further, the model setting system 70A includes an optical image simulation unit 64 that calculates the light intensity distribution of the optical image when the test pattern is exposed using the exposure apparatus defined by the tool parameter TP, and an empirical rule parameter. A resist image simulation unit 65 that calculates the shape of a developed resist image corresponding to the optical image by calculation, an exposure data input unit 66 of an actual exposure machine, a comparison unit 68, and an error factor analysis unit 69; ing. In the exposure data input unit 66, exposure data, which is data such as the shape of a resist image obtained by exposing a test pattern onto a wafer coated with a resist with an actual exposure machine and developing the resist, is not shown. It is input via an input device or a communication line (e-mail, Internet, etc.). The input exposure data is recorded in the exposure data file 67. The comparison unit 68 compares the shape of the resist image supplied from the resist image simulation unit 65 with the actual resist image supplied from the exposure data input unit 66 and supplies the comparison result to the control unit 61. When the difference between the shapes exceeds the allowable range, the error factor analysis unit 69 analyzes which parameter is the tool parameter or the rule of thumb parameter.

  The control unit 61 (feedback means) changes the value of the controllable parameter within the variable range according to the analysis result from the error factor analysis unit 69 when those shape errors exceed the allowable range. Then, the control unit 61 causes the optical image simulation unit 64 or the resist image simulation unit 65 to repeat the simulation. The values of the parameters TP and EP when the difference between the shapes of the two resist images finally falls within the allowable range are recorded in the parameter file 63, and the control unit 71 of the circuit design system 70B that performs circuit design next time. (See FIG. 2).

  FIG. 2 is a block diagram showing a circuit design system 70B for designing a reticle pattern while performing optical proximity correction (OPC: Optical Proximity Correction) using the parameters TP and EP supplied from the control unit 61 of FIG. It is. In FIG. 2, a circuit design system 70B includes a control unit 71 that comprehensively controls the operation of the entire system, a device pattern data input unit 72 that receives shape data of a device pattern to be designed, and the parameter TP , EP, an OPC process is performed on the input device pattern to design a reticle pattern, an exposure result prediction unit 75, an exposure data input unit 76 of an actual exposure machine, and a comparison unit 78. And. The shape data of the device pattern to be designed is recorded in the data file 73. The exposure result prediction unit 75 exposes the designed reticle pattern on the resist by an actual exposure machine by simulation, and develops the resist by simulation. The shape of the resist pattern (substantially equal to the device pattern to be designed) Predict.

  The exposure data input unit 76 of the actual exposure machine receives exposure data such as the shape of a resist image obtained by exposing a prototype reticle pattern with the actual exposure machine. This reticle pattern is obtained by actually forming the reticle pattern on a blank after the reticle pattern is designed by the circuit pattern design unit 74. The input exposure data is recorded in the exposure data file 77. The comparison unit 78 compares the shape of the resist image supplied from the exposure result prediction unit 75 with the actual resist image supplied from the exposure data input unit 76 and supplies the comparison result to the control unit 71. The control unit 71 causes the circuit pattern design unit 74 to repeatedly perform reticle pattern design when those shape errors exceed the allowable range. The shape data of the reticle pattern when the difference between the shapes of the two resist images finally falls within the allowable range is recorded in the data file 73 and transmitted to the reticle manufacturing unit 80 that performs mass production of the reticle. The

  Next, FIG. 3 shows a schematic configuration of a scanning exposure type exposure apparatus (projection exposure apparatus) EX comprising a scanning stepper for performing exposure of the reticle pattern created by the reticle pattern creation system 60 of FIG. In FIG. 3, an exposure apparatus EX includes an exposure light source 1, an illumination optical system 20 that illuminates a reticle R (mask) on which a transfer pattern is formed using exposure light IL from the exposure light source 1, and a reticle R. A reticle stage RST for driving the wafer, an optical system PL for projecting an image of the pattern of the reticle R onto a wafer W (substrate), a wafer stage WST for driving the wafer W, and a computer that comprehensively controls the operation of the entire apparatus. A main control system 31, an exposure control system 32, a stage control system 33, and other processing systems.

In this example, an ArF excimer laser light source (wavelength 193 nm) is used as the exposure light source 1. The exposure light source is replaced with an ArF excimer laser light source, an ultraviolet pulse laser light source such as a KrF excimer laser light source (wavelength 247 nm), an F ₂ laser light source (wavelength 157 nm), a YAG laser harmonic generation light source, a solid-state laser (semiconductor) A laser or the like harmonic generator or a mercury lamp (i-line or the like) can be used. The exposure amount control system 32 controls the center wavelength, wavelength width (for example, half width), oscillation frequency, average pulse energy, light emission timing, and the like of the exposure light IL of the exposure light source 1. The main control system 31 transmits and receives data such as exposure conditions to and from the host computer 34.

  In the illumination optical system 20, the exposure light IL enters from the exposure light source 1 via the mirror 2, and the cross-sectional shape is shaped into a predetermined shape by the lenses 3A and 3B. The shaped exposure light IL is incident on the diffractive optical element 6A fixed to the revolver 5 through the mirror 4, and has a predetermined light amount distribution (circular distribution, annular distribution, quadrupole) on the pupil plane of the illumination optical system 20. Diffracted in a plurality of directions to obtain a distribution or the like. The revolver 5 is also provided with diffractive optical elements 6B and 6C having other diffraction characteristics. By controlling the rotation angle of the revolver 5 via the drive unit 5a, one of the diffractive optical elements 6A, 6B, etc. is installed on the optical path of the exposure light IL in accordance with the set illumination condition.

  In FIG. 1, the exposure light IL that has passed through the diffractive optical element 6A is condensed by the relay lens 7, passes through a pair of prisms 8 and 9 made of an axicon system, and enters an incident surface of a fly-eye lens 10 as an optical integrator. Focused. The exit surface of the fly-eye lens 10 is the pupil surface of the illumination optical system 20. Further, by controlling the distance between the prisms 8 and 9, the light quantity distribution on the exit surface can be adjusted in the radial direction, and the coherence factor (σ value) can be adjusted. Note that an aperture stop plate 11 on which aperture stops 12A, 12B, 12C, 12D and the like having openings with large light quantity distributions are formed may be disposed in the vicinity of the fly-eye lens 10.

  The exposure light IL that has passed through the fly-eye lens 10 passes through the relay lens 13A, the fixed blind (fixed field stop) 14A that defines the illumination area 21R on the reticle R, and the scanning direction of the illumination area 21R and non-perpendicular to this. It sequentially passes through a movable blind (movable field stop) 14B for controlling the width in the scanning direction. The movable blind 14B is disposed on a surface substantially conjugate with the pattern surface (reticle surface) of the reticle R, and the fixed blind 14A is disposed on a surface slightly defocused from the surface conjugate with the reticle surface. The exposure light IL that has passed through the blinds 14A and 14B illuminates the illumination area 21R of the pattern area of the reticle R with a uniform illuminance distribution through the sub-condenser lens 13B, the optical path bending mirror 15, and the main condenser lens 16. The illumination optical system 20 includes members from the lenses 3A and 3B to the main condenser lens 16.

Under the exposure light IL, the pattern in the illumination area 21R of the reticle R is projected onto the wafer W at a projection magnification β (β is, for example, 1/4, 1/5, etc.) via the both-side telecentric projection optical system PL. Is projected onto a projection area elongated in the non-scanning direction on one shot area.
Projection optical system PL includes a variable aperture stop. Furthermore, in the projection optical system PL, for example, a predetermined lens element in a plurality of lens elements constituting the projection optical system is driven in the optical axis direction or tilted around an axis perpendicular to the optical axis. An imaging characteristic correction mechanism (not shown) that controls or adjusts the wavefront aberration of the projection optical system PL is also provided. The main control system 31 can control or adjust the numerical aperture and / or wavefront aberration of the projection optical system PL via the variable aperture stop and / or the imaging characteristic correction mechanism. In this example, a wafer W as a substrate to be exposed is obtained by applying a resist (photosensitive material) to the surface of a disk-shaped substrate made of a semiconductor such as silicon or SOI (silicon on insulator).

The optical system PL of this example is, for example, a refractive projection optical system, but a catadioptric projection optical system or the like can also be used. Hereinafter, the optical system PL will be described as the projection optical system PL. In FIG. 3, the Z axis is taken in parallel to the optical axis of the projection optical system PL, and the X axis along the non-scanning direction orthogonal to the scanning direction of the reticle R and the wafer W during scanning exposure in a plane perpendicular to the Z axis. In the following description, the Y axis is taken along the scanning direction.
First, reticle R is sucked and held on reticle stage RST. The reticle stage RST moves at a constant speed in the Y direction on the reticle base 24 and corrects, for example, a synchronization error (or a positional deviation amount between the pattern image of the reticle R and the shot area during exposure on the wafer W). The reticle R is scanned by fine movement in the X direction, the Y direction, and the rotation direction around the Z axis. The laser interferometers 25X and 25Y measure, for example, at least the position of the reticle stage RST in the X direction and the Y direction with a resolution of about 0.1 nm with reference to the projection optical system PL, and measure the rotation angle around the Z axis. These measured values are supplied to the stage control system 33 and the main control system 31. The stage control system 33 controls the position and speed of the reticle stage RST via a drive mechanism (such as a linear motor) (not shown) based on the measured value and the control information from the main control system 31.

  Further, since the exposure apparatus EX of this example performs exposure applying the liquid immersion method, the exposure apparatus EX is locally arranged so as to surround an optical element (not shown) on the most image plane side (wafer W side) constituting the projection optical system PL. A nozzle unit 40 constituting a part of the liquid immersion mechanism is provided. At the time of scanning exposure, the liquid LQ that transmits the exposure light IL such as pure water is supplied from the liquid supply device 41 to the flow path in the nozzle unit 40 through the supply pipe 42. The temperature of the liquid LQ in this example can be controlled within a predetermined variable range. A local space (local immersion space) surrounding the exposure area between the projection optical system PL and the wafer W is filled with the liquid LQ having a predetermined temperature. Further, the liquid LQ supplied in this way is recovered by the liquid recovery device 43 via the flow path in the nozzle unit 40 and the recovery pipe 44. The liquid supply device 41 and the liquid recovery device 43 are controlled by the main control system 31. In addition, as an immersion mechanism of this example, the immersion mechanism currently disclosed by the international publication 99/49504 pamphlet or the international publication 2004/053955 pamphlet etc. can also be used, for example.

  In FIG. 3, wafer W is held on wafer stage WST via a wafer holder (not shown). Wafer stage WST includes an XY stage 27 and a Z tilt stage 28 that move at a constant speed in the Y direction on wafer base 26 and move stepwise in the X and Y directions. The Z tilt stage 28 performs focusing and leveling of the wafer W based on the measurement value of the position of the wafer W in the Z direction by an auto focus sensor (not shown). The position of wafer stage WST in the XY plane and the rotation angles around the X, Y, and Z axes are measured by laser interferometers 29X and 29Y, and the measured values and control information from main control system 31 are used. Based on this, the stage control system 33 controls the operation of the wafer stage WST via a drive mechanism (not shown) such as a linear motor.

Further, an off-axis type alignment sensor ALG for measuring an alignment mark on the wafer W is disposed on the side surface of the projection optical system PL. Based on the detection result, the main control system 31 aligns the wafer W. I do.
At the time of exposure, the reticle stage RST and the wafer stage WST are driven, and the reticle R and one shot area on the wafer W are synchronously scanned in the scanning direction SD (Y direction) while being irradiated with the exposure light IL; The operation of stepwise moving wafer W in the X direction and Y direction by driving wafer stage WST is repeated. Thereby, the pattern image of the reticle R is exposed to each shot area on the wafer W by the step-and-scan method.

  Next, FIG. 4A shows an example of a test pattern used in the model setting system 70A of FIG. 1, and the X axis and Y axis of FIG. 4A are the reticle stage RST of the exposure apparatus EX of FIG. The same direction as the X-axis and Y-axis above. This test pattern includes a line-and-space pattern (hereinafter referred to as an L & S pattern) 45A in which linear transmission patterns are arranged at a relatively coarse pitch in the X direction, and an L & S having a pitch close to the resolution limit of the exposure apparatus EX. A pattern 45B and an isolated line pattern 45C extending in the X direction and the Y direction are included.

  Next, an example of processing for creating a reticle pattern by the reticle pattern creation system 60 of FIG. 1 of this example as a pattern data processing method will be described with reference to the flowcharts of FIGS. In this example, a reticle pattern (circuit pattern) formed on the reticle exposed by the exposure apparatus EX of FIG. 3 is created. The exposure apparatus EX is the latest model. As shown in FIG. 5, the reticle pattern creation process of this example sets the tool parameter TP that defines the exposure apparatus and the value of the empirical rule parameter EP that defines the development process, and sets the optical image model and the resist image model. As shown in FIG. 6, the model setting process is roughly divided into a circuit design process for designing a reticle pattern for a circuit pattern of an actual device based on the set model (values of parameters TP and EP).

  First, when model setting is started, in step 101 of FIG. 5, the parameter input unit 62 of the model setting system 70A of FIG. 1 is set to the same model as the exposure apparatus EX of FIG. Defines the tool parameters (TP) of exposure units (for example, the initial lot) selected in order from the newest manufacturing date (average value if there are multiple exposure units) and the photosensitive material on which the reticle pattern is exposed. The empirical rule parameter (EP) and information such as the shape of the test pattern shown in FIG. The values of the input parameters TP and EP are supplied to the control unit 61, and information such as the shape of the test pattern is supplied to the optical image simulation unit 64. In the next step 102, the control unit 61 sets initial values of parameters TP and EP (input values themselves here) in the optical image simulation unit 64 and the resist image simulation unit 65, respectively.

  In the next step 103, the optical image simulation unit 64 uses the optical image model (a model almost similar to the exposure apparatus EX) defined by the set tool parameter TP by simulation, so that the test pattern 45A in FIG. The light intensity distribution of the optical image when .about.45C is exposed is obtained, and information on this optical image is supplied to the resist image simulation unit 65. In the next step 104, the resist image simulation unit 65 projects the optical image onto a resist image model (resist) defined by the empirical rule parameter EP by simulation, and then develops the resist image obtained by developing. Find the shape. An example of the calculated resist image thus obtained is resist patterns 46A, 46B, and 46C having line widths dc1, dc2, dc3, and dc4 in FIG. 4B, respectively. For convenience of explanation, it is assumed that the projection optical system projects an equal-size erect image.

  In parallel with the operation so far, also in the exposure apparatus EX of FIG. 3, the resist is applied to the test patterns 45A to 45C of FIG. 4A under the same conditions as the empirical rule parameter EP used in Step 104. The wafer is exposed, and the exposed wafer is developed under the same conditions as the rule of thumb parameter EP. As shown in FIG. 4C, resist patterns 47A, 47B, and 47C having actual line widths of de1, de2, de3, and de4 are obtained. When exposure is performed by a plurality of exposure apparatuses EX, the average value of the line widths is changed to line widths de1 to de4.

  In step 105 of FIG. 5, the exposure data input unit 66 of the actual exposure machine of FIG. 1 reads the shape data (line widths de1 to de4) of the resist patterns 47A to 47C formed by the exposure of the exposure apparatus EX. . In the next step 106, the comparison unit 68 performs the line width dci (i = 1 to 4) of the resist patterns 46 </ b> A to 46 </ b> C of FIG. 4B obtained by calculation in step 104 and the actual exposure in step 105. In order to compare the obtained resist patterns 47A to 47C of FIG. 4C with the line width dei, a shape error δ1i which is an absolute value of the deviation between the two is obtained from the following equation and supplied to the control unit 61.

δ1i = | dci-dei | (1)
In the next step 107, when at least one of the shape errors δ1i (i = 1 to 4) is equal to or greater than a predetermined allowable value ε1i, the process proceeds to step 108 and whether the value of the tool parameter TP is changed. Whether it is determined. Specifically, the number of manufactured exposure apparatuses EX in FIG. 3 increases, and the average value of the tool parameter TP of the latest predetermined number of exposure apparatuses EX becomes the value of the tool parameter TP set so far. It may change greatly compared to this. In this case, the process proceeds to step 111, the value of the tool parameter TP is changed to a value measured by the latest exposure apparatus EX, and the operations after the optical image simulation in step 103 are repeated.

  If the value of the tool parameter TP has not been changed in step 108, the process proceeds to step 109, where the error factor analysis unit 69 in FIG. 1 determines the error factor based on the shape error δ1i (i = 1 to 4). Is analyzed. Specifically, among the test patterns 45A to 45C in FIG. 4A, when the shape errors δ12 to δ14 exceed the allowable values in both the L & S pattern 45B (dense line) and the isolated line pattern 45C, the resist image model Is determined to have a factor. In this case, the process proceeds to step 110, where some values of the empirical rule parameter EP are changed within the variable range and set in the resist image simulation unit 65, and then the process proceeds to step 104, where the resist pattern The operations after the shape recalculation are repeated.

  In step 109, when only the shape errors δ13 and δ14 of the isolated line pattern 45C in FIG. 4A are equal to or larger than the allowable values, it is determined that there is a factor in the optical image model. In this case, the process proceeds to step 111, and values of some of the variable parameters in the tool parameter TP are changed within the variable range and set in the optical image simulation unit 64, and then to step 103. The operation after the recalculation of the optical image is repeated. Thereby, the parameters TP and EP are optimized.

  If all the shape errors δ1i (i = 1 to 4) become smaller than the allowable value ε1i in step 107, the control unit 61 proceeds to step 112, and the current tool parameter TP and experience The value of the law parameter EP is stored in the parameter file 63 and transmitted to the control unit 71 of the circuit design system 70B of FIG. Thus, the optical image model and the resist image model are completed, and circuit design is started in step 120 of FIG.

  Next, in the circuit design system 70B of FIG. 2, when circuit design is started in step 120 of FIG. 6, first, in step 121, the device pattern data input unit 72 of FIG. (Hereinafter also referred to as mask design data), and shape data is supplied to the circuit pattern design unit 74. Further, the values of the parameters TP and EP supplied to the control unit 71 from the control unit 61 in FIG. 1 are supplied to the circuit pattern design unit 74 and the exposure result prediction unit 75, and data are transmitted via the device pattern data input unit 72. It is recorded in the file 73.

Note that mask design data, that is, pattern data for reticle pattern drawing, refers to each pattern constituting a circuit pattern to be formed on a reticle (including a photomask) used in a lithography process in manufacturing a semiconductor integrated circuit or the like. This is information including position information, shape information, and transmittance information.
Further, the mask design data is not limited to the pattern data for drawing the reticle pattern, and it is also possible to use pattern data used in a variable mask whose pattern shape is variable. In the variable mask, for example, a large number of fine openable and closable windows are formed on a glass substrate, and a desired circuit pattern is formed on the glass substrate by opening and closing each window with liquid crystal. Contains the configuration to display.

  As the mask design data, as described above, when the pattern is formed on the reticle, binary data in which the value of the portion that becomes the transmissive portion is 1 and the value of the portion that becomes the light shielding portion is 0 is bit. A bitmap data format (also called a raster data format) arranged in a map can be used. As the mask design data, a vector such as a format (for example, GDS2 format) in which the pattern expressed in the bitmap data format is divided into minute rectangles and triangles and the X and Y coordinate values of the vertices are described. It is also possible to use data in data format.

In the next step 122, the circuit pattern design unit 74 in FIG. 2 performs pattern design for obtaining a circuit pattern of an actual device in consideration of OPC based on the parameters TP and EP, and predicts the design data as an exposure result prediction. Supply to part 5.
Specifically, in order to explain an optical proximity effect (OPE) that is an optical proximity effect of a projected image, it is assumed that the test pattern shown in FIG. 7A is projected onto the wafer by the exposure apparatus EX shown in FIG. To do. This test pattern includes, for example, L & S patterns 51, 53, and line patterns 52, 54, and 55 having the same line width D arranged on the test reticle TR in such a state that they can be regarded as different pitches P1, P2 and almost isolated lines in the X direction. It is an isolated line pattern. The test pattern is projected onto the wafer TRW by the exposure apparatus EX, and then the resist on the wafer TRW is developed. As shown in FIG. 7B, the resist pattern 51W and 53W in which line patterns 52W and 54W having different line widths d1 and d2 are arranged in the X direction and an isolated line pattern having a line width d3 are obtained by development processing. 55W is obtained. As described above, the line width of the resist pattern varies depending on the pitch depending on the OPE even if the pattern has the same line width.

  A curve C1 in FIG. 8 shows an example of the OPE characteristic calculated by the tool parameter TP of the exposure apparatus EX when images of various L & S patterns having the same line width and different pitches are exposed by the exposure apparatus EX in FIG. . In FIG. 8, the horizontal axis represents the pattern pitch (nm) of the projected image on the wafer, and the vertical axis represents the line width (nm) of the projected image on the wafer. In the curve C1 of FIG. 8, the line width is small when the pattern pitch is around 500 nm.

In the circuit pattern design unit 74 of FIG. 2, for example, after obtaining the OPE characteristic of FIG. 8 by calculation, the line width of the circuit pattern finally obtained becomes the line width input in step 121 of FIG. The line width of the reticle pattern is adjusted so as to cancel out the OPE characteristic. Further, when an unnecessary optical image is generated, an auxiliary pattern is added to cancel the optical image.
Assuming that the circuit patterns necessary for the actual device are the circuit patterns 48 and 49 in FIG. 9A, the circuit pattern design unit 74 projects the circuit pattern 48 as shown in FIG. The line width is slightly smaller than the image pattern 48R obtained by enlarging the reticle pattern 56 and the circuit pattern 49 with the reciprocal of the projection magnification of the projection optical system. A thick reticle pattern 57 is generated. For convenience of explanation, it is assumed that an erect image is projected at the same magnification. Further, when an unnecessary optical image is formed only by the reticle patterns 56 and 57, auxiliary patterns 56A and 57A are added to cancel the unnecessary optical image.

  Next, in step 123 of FIG. 6, the exposure result prediction unit 75 exposes the designed reticle pattern onto the photosensitive material defined by the empirical parameter EP with the exposure apparatus defined by the tool parameter TP. Thereafter, the exposure result predicting unit 75 predicts the shape of the resist pattern obtained by developing the photosensitive material (the line width is Dci (i = 1, 2,...)). The predicted resist pattern shape is almost equal to the circuit pattern shape of the actual device input in step 121.

  Further, the reticle pattern that has been designed in step 122 and then prototyped is exposed on a wafer coated with a resist under the same conditions as the empirical parameter EP used in step 123 using the exposure apparatus EX of FIG. Then, by developing the exposed wafer under the same conditions as the rule-of-thumb parameter EP, as shown in FIG. 9C, resist patterns 56W, 57W, etc. having actual line widths of De1, De2, etc., respectively, can be obtained. . When exposure is performed with a plurality of exposure apparatuses EX, the average value of the line widths is changed to the line widths De1, De2, and the like.

  Then, in step 124 of FIG. 6, the exposure data input unit 76 of the actual exposure machine of FIG. 2 uses the shape data (line widths De1, De2, etc.) of the resist patterns 56W, 57W, etc. formed by the exposure of the exposure apparatus EX. Is read. In the next step 125, the comparison unit 78 of FIG. 2 shows the resist pattern line width Dci (i = 1, 2,...) Obtained by calculation in step 123 and the figure obtained by actual exposure in step 124. In order to compare with the line width Dei of the resist pattern 9 (C), a shape error δ2i which is an absolute value of the deviation between the two is obtained from the following equation and supplied to the controller 71.

δ2i = | Dci−Dei | (2)
In the next step 126, when at least one of the shape errors δ2i is equal to or greater than a predetermined allowable value ε2i, the control unit 71 causes the circuit pattern design unit 74 to perform redesign of the reticle pattern.
If all the shape errors δ2i become smaller than the allowable value ε2i in step 126, the control unit 71 proceeds to step 127 and transfers the data of the current reticle pattern (circuit pattern) to the data file 73. In step 128, the reticle pattern data is transmitted to a reticle manufacturing apparatus (not shown). Thus, the reticle pattern corresponding to the circuit pattern of the actual device is completed, and mass production of the reticle is started.

After that, a case where the reticle pattern created by the creation method of FIGS. 5 and 6 is exposed by the exposure apparatus EX of FIG. 3 will be described. Before exposing the reticle pattern with the exposure apparatus EX, it is checked whether the parameter values of the exposure apparatus EX at the present time are changed with respect to the tool parameter values of the exposure apparatus read at step 101. If the parameter value of the exposure apparatus EX has been changed, as an example, the tool parameter value of the exposure apparatus read in step 101 is adjusted. This is because the shape of the reticle pattern is optimized for this tool parameter. After adjusting the values of tool parameters of the exposure apparatus, on the photosensitive material defined by the specified heuristics parameter EP when creating the reticle pattern, the reticle pattern is exposed using the exposure apparatus EX, a developing I do. By doing so, a circuit pattern of a desired device can be formed with high accuracy.

  As described above, according to the reticle pattern creation method and reticle pattern creation system 60 of this example, the resist pattern creation system compares the resist pattern by simulation of the test patterns 45A to 45C with the resist pattern by the exposure apparatus EX. Since the value of the tool parameter TP to be input is set, an image (resist pattern) predicted from the reticle pattern by simulation and an image (resist pattern) actually formed using the exposure apparatus EX when designing the reticle pattern ) Is smaller. Therefore, for example, as shown in steps 122 to 126 in FIG. 6 by trial and error, the number of times the reticle pattern design is repeated can be reduced, and the reticle pattern creation efficiency is high.

  Further, the tool parameter TP includes parameters (for example, parameters TP6 to TP12 in Table 1) that are different for each type of exposure apparatus or each number. Therefore, for example, with regard to an exposure apparatus that is moving from trial production to mass production, the tool parameters of the exposure apparatus that actually performs exposure of the reticle pattern created by the reticle pattern creation method can be taken into consideration and optimized for the exposure apparatus. Reticle reticle patterns can be designed.

  Note that when the reticle pattern created by the creation method of FIGS. 5 and 6 is exposed by the exposure apparatus EX of FIG. 3, the value of the tool parameter TP of the exposure apparatus EX of FIG. 3 is stored in step 101 of FIG. If the value TPD is different from the measured value TPD (that is, the value TPD of the tool parameter TP used at the time of circuit design in step 121 in FIG. 6), the variable parameter (for example, the parameter in Table 1) of the tool parameter TP of the exposure apparatus EP The value of TP1 to TP5) may be matched with the value TPD of the tool parameter TP used when designing the circuit.

  In addition to the case of directly controlling the value of the variable parameter as described above, as shown in FIG. 10, a curve predicted from the value TPD of the tool parameter TP used at the time of circuit design in steps 122 and 123 of FIG. When the OPE characteristic indicated by the curve C2 predicted from the tool parameter TP of the exposure apparatus EP in FIG. 3 deviates from the OPE characteristic indicated by C1, the value of the tool parameter TP of the exposure apparatus EX is changed to another result. The curve C2 may be adjusted to the curve C1 by adjusting within a range that does not substantially affect the image characteristics. Specifically, in the exposure apparatus EX, for example, by finely adjusting the coherence factor (σ value), the point C2D on the curve C2 is brought close to the curve C1, and by finely adjusting the numerical aperture NA, the point on the curve C2 is adjusted. By bringing C2B closer to the curve C1, the OPE characteristics can be matched. As a result, a desired device pattern can be obtained by exposing the reticle pattern with the exposure apparatus EX.

If the person who creates the reticle pattern using the reticle pattern creation system 60 of FIG. 1 in the above embodiment is a device manufacturer, the parameters of the exposure apparatus acquired by the parameter input unit 62 and the exposure data input unit Information of the actual photosensitive material image acquired in 66 may be acquired from the exposure apparatus manufacturer via a recording medium or a communication line (e-mail, Internet).
In the above embodiment, the comparison unit 68 compares the photosensitive material image (resist pattern) formed after the photosensitive material is actually developed with the simulated photosensitive material image. However, instead, the latent image on the photosensitive material formed by actually projecting the test pattern may be compared with the image (latent image) on the photosensitive material by simulation. In this way, when a latent image is targeted, a simulation may be performed in consideration of resist sensitivity and sensitivity to exposure light as an empirical rule parameter EP (second parameter).

The “information of the photosensitive material image by simulation” of the present invention includes a light intensity distribution, and the “information of the actual photosensitive material image” includes a measurement value measured by a scanning electron microscope (SEM). Also, image data captured by an image sensor is included.
In addition, the reticle pattern OPC process in the above embodiment includes a process of making both end portions of the line pattern relatively thicker than the central portion.
Further, as a pattern subjected to OPC processing, for example, a correction pattern based on a mask pattern obtained by adding a correction pattern to a corner portion of a mask pattern or a portion that is separated from an adjacent pattern by a predetermined distance or more, a lithography simulator, or experimental data. Generated mask patterns, patterns such as “sheriff pattern” or “hammer head pattern” that prevent pattern corners from being rounded, or mask patterns that include “bias” that corrects line width variation of the pattern, etc. There is also.

The present invention can be similarly applied not only to exposure with a scanning exposure type projection exposure apparatus but also with a batch exposure type projection exposure apparatus. The present invention also relates to a dry type exposure apparatus that does not supply a liquid between the projection optical system and the substrate, or an exposure apparatus that uses extreme ultraviolet light (EUV (Extreme Ultravolet) light) such as soft X-rays as exposure light. It can also be applied to the case where exposure is performed.
Further, when a semiconductor device is manufactured using the exposure apparatus of the above-described embodiment, the semiconductor device includes a step of designing a function and performance of the device, a step of manufacturing a reticle based on this step, and a wafer from a silicon material. A substrate processing step including a step of forming, a step of exposing a reticle pattern to the substrate (wafer) by the exposure apparatus of the above-described embodiment, a step of developing the exposed substrate, a heating (curing) of the developed substrate, and an etching step The device is manufactured through a device assembly step (including a dicing process, a bonding process, and a packaging process) and an inspection step.

  Further, the present invention is not limited to application to a semiconductor device manufacturing process, for example, a manufacturing process of a display device such as a liquid crystal display element formed on a square glass plate or the like, or a plasma display, or imaging. The present invention can be widely applied to manufacturing processes of various devices such as devices (CCD, etc.), micromachines, MEMS (Microelectromechanical Systems), thin film magnetic heads using ceramic wafers as substrates, and DNA chips. Furthermore, the present invention can also be applied to a manufacturing process when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithography process.

  In addition, this invention is not limited to the above-mentioned embodiment, Of course, a various structure can be taken in the range which does not deviate from the summary of this invention.

It is a block diagram which shows the reticle pattern production system used in an example of embodiment. It is a block diagram which shows the structure of the circuit design system in FIG. It is a perspective view which shows the exposure apparatus used in an example of embodiment. (A) is an enlarged view showing an example of a test pattern, (B) is an enlarged view showing a resist pattern obtained by simulation from the test pattern, and (C) is a resist pattern obtained by exposure of an actual exposure machine from the test pattern. It is an enlarged view. It is a flowchart which shows the model setting process among the reticle pattern creation methods of an example of embodiment. It is a flowchart which shows the circuit design process among the reticle pattern creation methods of an example of embodiment. It is explanatory drawing of an optical proximity effect (OPE), (A) is an enlarged view which shows an example of a reticle pattern, (B) is an enlarged view which shows the resist pattern corresponding to the reticle pattern of FIG. 7 (A). It is a figure which shows an example of an OPE characteristic. (A) is an enlarged view showing an example of a circuit pattern of an actual device, (B) is an enlarged view showing an example of a reticle pattern created by the method of the embodiment, and (C) is an exposure of the reticle pattern with an actual exposure machine. It is an enlarged view which shows an example of the resist pattern obtained by doing. It is a figure which shows the case where two OPE characteristics differ.

Explanation of symbols

  EX ... exposure apparatus, 60 ... reticle pattern generation system, 61 ... control unit, 62 ... parameter input unit, 64 ... optical image simulation unit, 65 ... resist image simulation unit, 66 ... exposure data input unit of actual exposure machine, 68 ... Comparison unit 69 ... Error factor analysis unit 70A ... Model setting system 70B ... Circuit design system

Claims (17)

In a pattern data processing method for processing mask pattern design data,
A first step of obtaining light intensity information by the actual exposure machine of a test pattern by simulation using a first parameter of an actual exposure machine using a mask on which a mask pattern based on the design data is formed;
Information on the image of the photosensitive material by simulation using the second parameter relating to the photosensitive material on which the image of the mask pattern is formed and the light intensity information obtained by the actual exposure machine obtained in the first step for the photosensitive material. A second step of acquiring
Based on the information of the image of the photosensitive material obtained by the simulation obtained in the second step and the information of the image of the actual photosensitive material formed on the photosensitive material by using the actual exposure machine. A third step of obtaining a shape error between the image of the photosensitive material by the simulation and the image of the actual photosensitive material;
A fourth step of changing at least one of the first parameter and the second parameter in the simulation so that the shape error obtained in the third step falls within a predetermined allowable range;
And a fifth step of designing the mask pattern using the values of the first parameter and the second parameter when the shape error falls within a predetermined allowable range. Processing method. At least one of the first parameter and the second parameter includes a variable parameter and a non-variable parameter ,
In the fourth step, when the shape error exceeds the allowable range, the value of the variable parameter in the simulation is changed, and the operations from the first step or the second step to the third step are performed. The pattern data processing method according to claim 1, wherein the pattern data processing method is repeated. The first parameter includes an average value related to light intensity information of a plurality of actual exposure machines,
3. The pattern according to claim 1, wherein the information of the actual photosensitive material image includes an average value of values relating to the photosensitive material image formed by using the plurality of actual exposure machines. Data processing method.   The pattern data processing method according to claim 3, wherein the plurality of actual exposure machines are selected in an order related to a manufacturing date.   5. The method according to claim 1, wherein the fifth step includes a step of designing the mask pattern so as to correct an optical proximity effect of the actual exposure machine. 6. Pattern data processing method.   The first parameter is a variable parameter such as the numerical aperture of the optical system of the actual exposure machine, the wavefront aberration of the optical system, the coherence factor of the illumination optical system of the actual exposure machine, and the exposure used in the actual exposure machine. The pattern data processing method according to claim 1, comprising a center wavelength of light and a wavelength width of the exposure light. The actual exposure machine is an immersion exposure apparatus that supplies a liquid between an optical system and a substrate to be exposed, and exposes the substrate with exposure light through the optical system and the liquid.
The pattern data processing method according to claim 1, wherein the first parameter includes a temperature of the liquid of the immersion exposure apparatus as a variable parameter.   The first parameter is a non-variable parameter such as apodization of the optical system of the actual exposure machine, polarization aberration, flare, aberration caused by heat, and light quantity distribution of the secondary light source in the illumination optical system of the actual exposure machine. The pattern data processing method according to claim 1, wherein the pattern data processing method is included.   The pattern data processing method according to claim 1, further comprising a step of acquiring the first parameter of the actual exposure machine.   10. The method according to claim 1, further comprising a step of acquiring information on an image of the actual photosensitive material obtained by forming an image of the test pattern on the photosensitive material using the actual exposure machine. The pattern data processing method according to any one of the above. In a pattern data processing system for processing mask pattern design data,
First simulation means for obtaining light intensity information by the actual exposure machine of the test pattern by simulation using a first parameter of an actual exposure machine using a mask on which a mask pattern based on the design data is formed;
A second parameter for obtaining the image information of the photosensitive material by simulation is obtained by using the second parameter relating to the photosensitive material on which the image of the mask pattern is formed and the light intensity information by the actual exposure machine obtained by the first simulation means. 2 simulation means;
Based on the information of the image of the photosensitive material obtained by the second simulation means and the information of the image of the actual photosensitive material formed on the photosensitive material by using the actual exposure machine. Comparing means for obtaining a shape error between the image of the photosensitive material by the simulation and the image of the actual photosensitive material;
At least one of the first parameter and the second parameter used in the first simulation unit and the second simulation unit is changed so that the shape error obtained by the comparison unit falls within a predetermined allowable range. Change means,
Mask pattern design means for designing the mask pattern using the values of the first and second parameters when the shape error obtained by the comparison means falls within a predetermined allowable range. Characteristic pattern data processing system. At least one of the first parameter and the second parameter includes a variable parameter and a non-variable parameter ,
The changing unit changes the value of the variable parameter when the shape error obtained by the comparing unit exceeds the allowable range, and supplies the first parameter to the first simulation or the first parameter. The pattern data processing system according to claim 11, wherein the second parameter is supplied to two simulation means.   The pattern data processing system according to claim 11, wherein the mask pattern design unit designs the mask pattern so as to correct an optical proximity effect of the actual exposure machine.   The pattern data processing system according to claim 11, further comprising a parameter acquisition unit that acquires the first parameter of the actual exposure machine.   12. An image information acquisition unit that acquires information of an image of the actual photosensitive material obtained by forming an image of the test pattern on the photosensitive material using the actual exposure machine. The pattern data processing system according to claim 14. An exposure method for exposing a substrate with exposure light through a pattern and an optical system,
When the pattern is a mask pattern created by the pattern data processing method according to any one of claims 1 to 10,
Based on the value of the first parameter used in the fifth step, the numerical aperture of the optical system, the wavefront aberration of the optical system, the coherence factor of the illumination optical system that illuminates the pattern, and the center wavelength of the exposure light And adjusting a parameter including at least one of the wavelength widths of the exposure light,
An exposure method comprising: exposing the substrate through the pattern with the exposure light after adjusting the parameters. An exposure apparatus that exposes a substrate with exposure light via a pattern and an optical system,
Parameter adjustment for adjusting at least one parameter of the numerical aperture of the optical system, the wavefront aberration of the optical system, the coherence factor of the illumination optical system that illuminates the pattern, the center wavelength of the exposure light, and the wavelength width of the exposure light With means ,
When the pattern is a mask pattern created by the pattern data processing system according to any one of claims 11 to 15, the parameter adjusting means is the first used by the mask pattern designing means . An exposure apparatus that adjusts the at least one parameter based on a value of one parameter .

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