JP2005109418A - Method for determining parameter for signal processing, alignment method, and method and system for exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of determining a parameter for signal processing, by determining whether a set signal processing parameter is optimal, to provide an aligning method, and to provide a method and system for exposure. <P>SOLUTION: The method is provided, wherein a parameter is determined which can be set for signal processing for detecting a position of a mark formed in an object. The method comprises steps of generating a first waveform by imaging, on an imaging device, an optical image of the mark, generating a second waveform by shifting the first waveform by a predetermined shifting tolerance in a single pixel in the imaging device, and determining the parameter by performing signal processing by varying the parameter toward the second waveform. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention generally relates to an exposure method and apparatus for exposing an object to be processed such as a single crystal substrate for a semiconductor wafer and a glass substrate for a liquid crystal display (LCD) in photolithography, and in particular, optimizes alignment parameters. On how to do. Here, the “alignment parameter” is a parameter having some relationship with the alignment between the reticle and the object to be processed. The present invention is suitable for performing alignment with high accuracy in a situation where a wafer process error may occur.

  Due to the recent demand for miniaturization and thinning of electronic equipment, a projection exposure apparatus for manufacturing a semiconductor device is drawn on a reticle or mask (in this application, these terms are used interchangeably). It is required to project and expose a circuit pattern on a wafer with high resolution. Since the projection resolution of the circuit pattern depends on the numerical aperture (NA) of the projection optical system and the exposure wavelength, a method of increasing the NA of the projection optical system and a method of shortening the exposure light wavelength are adopted for higher resolution. Has been. In addition, a CMP (Chemical Mechanical Polishing) process or the like has been introduced as a flattening technique for solving the problem of insufficient depth of focus of an exposure apparatus associated with increasing the NA of the projection optical system.

  One of the important parameters for exposure is the overlay accuracy, which is the accuracy when overlaying several patterns on the wafer. In order to obtain the desired overlay accuracy, it is necessary to align the reticle and wafer with high precision (alignment of the relative position of the reticle and wafer), and the alignment accuracy increases as the circuit pattern becomes finer. It is getting strict. The accuracy required for alignment is typically about 1/3 of the circuit line width. For example, the required accuracy in the current 180 nm design is 1/3 of 60 nm.

  The alignment between each shot of the wafer and the reticle is performed by detecting the position of the alignment mark corresponding to each shot exposed and transferred onto the wafer simultaneously with the circuit pattern on the reticle. The alignment mark detects its position by receiving light from the alignment mark with a CCD camera via an optical system and processing the obtained electrical signal using various parameters. Then, the wafer is positioned with respect to the reticle based on the detection result. Specifically, the detection result includes, for example, wafer magnification, wafer rotation, shift amount, and the like.

  In order to detect the alignment mark with high accuracy, it is necessary to optimize signal processing parameters. This is because the shape and state of the alignment mark change depending on the device manufacturing process, and the optimum parameters for signal processing differ accordingly. If the position of the alignment mark is detected using a parameter that has not been optimized, a detection error may occur, leading to a decrease in overlay accuracy.

  The current state of optimization of signal processing parameters is that the AGA using a certain signal processing parameter aligns each shot of the wafer with the reticle, exposes several sender heads, and results from the overlay inspection system. Determined by. If the result of the superposition apparatus is satisfactory, exposure of one to several lots is performed while performing alignment with such signal processing parameters. If the result of the overlay apparatus is bad, alignment is performed by changing the signal processing parameter, and the sender head is exposed to repeat until the result of the overlay inspection apparatus is improved.

  However, as the alignment accuracy required with the rapid miniaturization of circuit patterns increases and detection accuracy higher than the size of one pixel of a CCD camera is required, signal processing using conventional optimal parameters However, the detection accuracy may not be sufficient. In general, when performing alignment between a reticle and a wafer, there is an alignment error factor caused by the wafer called WIS (Wafer Induced Shift) as a major factor that deteriorates the alignment accuracy of the wafer. A pixel is a minimum unit for forming an image, and is a cell (basic unit) of each CCD camera that performs photoelectric conversion.

  Therefore, the present inventor applies the signal processing parameters of the sender head to all the wafers in the lot as in the conventional case, so that the alignment accuracy is lowered. Therefore, the signal processing parameters are set in the lot or in the wafer based on the alignment result. We considered changing it dynamically.

As a technique for dynamically changing and optimizing signal processing parameters, for example, a pseudo waveform in which an imaging state is changed is directly created from an alignment waveform captured by a CCD camera, and a plurality of such pseudo waveforms are generated. A proposal has been made to optimize a signal processing parameter that can detect a changed imaging state by performing signal processing using the signal processing parameter (see, for example, Patent Document 1).
JP 2002-140663 A

  However, the signal processing parameter optimization technique described in Patent Document 1 directly creates a pseudo waveform from the alignment waveform detected by the CCD camera. When an error occurs, the optimum signal processing parameter obtained from such part also includes an error, and may not actually be the optimum signal processing parameter.

  Accordingly, an object of the present invention is to provide a method, an alignment method, an exposure method, and an apparatus for determining whether a set signal processing parameter is optimal and determining a signal processing parameter. .

  In order to achieve the above object, a method for determining a parameter as one aspect of the present invention is a method for determining a parameter that can be set for signal processing for detecting a position of a mark formed on an object, Generating a first waveform obtained by forming an optical image of the mark on an image sensor, and shifting the first waveform by a predetermined shift amount within one pixel of the image sensor; And a step of determining the parameter by performing the signal processing by changing the parameter with respect to the second waveform.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, it is possible to provide a method, an exposure method and an apparatus for determining whether or not a set signal processing parameter is optimal and optimizing the signal processing parameter.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, “apparatus setting JOB parameter” means a parameter value group set in an actual exposure apparatus for wafer exposure, and “apparatus non-setting JOB parameter” means exposure of the wafer. For this reason, it means a set of parameter values that are not set in an actual exposure apparatus but are functionally settable. The “alignment parameter” is a parameter having some relationship with the alignment between the reticle and the object to be processed. The “alignment parameter” includes not only numerical values of parameters that can be set numerically but also conditions such as selection data of setting parameters that do not directly apply to numerical values, such as selection of a signal processing method.

  FIG. 1 is a block diagram of an exposure system 1 for realizing this embodiment. In the exposure system 1, reference numerals 100 and 200 denote semiconductor exposure apparatuses, which expose a circuit pattern on a reticle onto a wafer. Reference numeral 300 denotes a host computer that optimizes the alignment parameters of the semiconductor exposure apparatus 100, and is constituted by a personal computer or a workstation. Reference numeral 400 denotes a storage device such as a hard disk, which is a database of alignment parameters (for example, signal processing parameters (filter order, processing window center distance, etc.) for the alignment waveform, signal processing method, etc.) by the exposure apparatuses 100 and 200. Store.

  The storage device 400 may be built in the exposure apparatus 100 or 200 or the host computer 300. In the present embodiment, the host computer 300 that accesses the exposure apparatuses 100 and 200 and the storage device 400 to optimize the alignment parameters of the present embodiment is a network 500 such as a LAN (Local Area Network). It is connected. In FIG. 1, there are two semiconductor exposure apparatuses. Of course, one or more than two semiconductor exposure apparatuses may be connected to the network 500.

  FIG. 2 is a block diagram showing the overall configuration of the semiconductor exposure apparatus 100 shown in FIG. The semiconductor exposure apparatus 100 exposes the pattern of the reticle 130 onto the wafer 700.

  In FIG. 2, reference numeral 110 denotes a laser light source unit. Laser light as exposure light emitted from the laser light source unit 110 is shaped by the illumination optical system 120 to illuminate the pattern of the reticle 130.

  The reticle 130 is held on a reticle stage 140 that can move in the reticle scanning direction in the XY plane in FIG. Reference numeral 150 denotes a projection optical system having a predetermined reduction magnification. The pattern of the reticle 130 illuminated through the illumination optical system 120 is projected onto one shot area of the wafer 700 by the projection optical system 150 to expose the wafer 700. Photoresist (photosensitive material) is applied to the wafer 700, and a latent image is formed by exposure. The wafer 700 is placed on the wafer stage 170 via the wafer chuck 160. Reference numeral 600 denotes an alignment unit (alignment scope) that can detect an alignment mark 710 formed on the wafer 700 as shown in FIG.

  The wafer stage 170 moves the mounted wafer 700 in the plane of the stage (in the x-axis and y-axis directions), up and down (in the z-axis direction), and in the direction of inclination and rotation around each axis, thereby enabling positioning control. is there. The projection optical system 150 is focused on the wafer 700 by positioning control of the wafer stage 170 in the z-axis direction.

  Control of movement and positioning of reticle stage 140 and wafer stage 170 is performed based on the position information obtained by measuring stage position and orientation information using a sensor (not shown).

  Reticle stage 140 and wafer stage 170 are each connected to control unit 180 and can be controlled synchronously by exchanging data in real time. Similarly, the laser light source unit 110 is also connected to the control unit 180, and can be controlled in synchronization with the timing of light emission and the movement of the reticle stage 140 and the wafer stage 170.

  Hereinafter, the principle of position measurement of the alignment mark 710 formed on the wafer 700 will be described with reference to FIG. Here, FIG. 3 is a block diagram showing the main components of the alignment unit 600 shown in FIG. Illumination light from the light source 610 is reflected by the beam splitter 620, passes through the lens 630, is divided by the beam splitter 650, and is received by the CCD sensors 660 and 670, respectively. Here, the alignment mark 710 is enlarged at an image forming magnification of about 100 times and formed on the CCD sensors 660 and 670. The CCD sensors 660 and 670 are used for measuring the position of the alignment mark 710 in the X direction and for measuring the position of the alignment mark 710 in the Y direction, respectively. It is installed with a degree of rotation.

  Since the measurement principle of the alignment mark 710 in the X direction and the Y direction is the same, the position measurement in the X direction will be described below. First, the alignment mark 710 for position measurement will be described. As shown in FIG. 4A, the alignment mark 710 of this embodiment is a strip-shaped position measurement mark (alignment mark of 4 μm in the alignment measurement direction (X direction) and 30 μm in the non-measurement direction (Y direction). A plurality of (four in FIG. 4A) are arranged at a preset interval (L = 20 μm) in the X direction.

  As shown in FIG. 4B, the cross-sectional structure of the position measurement mark 712 has a concave shape by etching, and a resist (not shown) is applied on the position measurement mark 712.

  FIG. 4C shows an alignment waveform DS obtained by photoelectrically converting the reflected light obtained by irradiating the plurality of position measurement marks 712 with illumination light by the CCD sensors 660 and 670. Appropriate signal processing is performed on the alignment waveform DS shown in FIG. 4C to detect each position measurement mark position (M1, M2, M3, M4 in order from the left in FIG. 4C).

  Next, an alignment operation procedure for controlling the alignment between the reticle 130 and the wafer 700 will be described. First, as preparation for JOB (apparatus setting JOB) for projecting the circuit pattern of the reticle 130 on the wafer and exposing it, the wafer 700 to be exposed is loaded into the semiconductor exposure apparatus 100, and the reticle 130 corresponding to the wafer 700 is used as the semiconductor. It is set in the exposure apparatus 100.

  Next, an alignment parameter necessary for aligning the wafer 700 and the reticle 130 with respect to the apparatus setting JOB is set to a specific value (stored in a storage unit (memory) not shown in the semiconductor exposure apparatus 100). The wafer stage 170 holding the alignment unit 600 and the wafer 700 is driven by the value of the apparatus setting JOB parameter to measure information on the position and the like. A laser interferometer (not shown) is provided as a position measurement sensor for the wafer stage 170, and the position (shift amount) of the wafer 700 on the wafer stage 170 based on the positional information of the alignment mark 710 from the alignment unit 600 and the output of the laser interferometer. ), Measurement of wafer rotation amount, wafer magnification, and the like is performed. Such measurement is performed by a global alignment method.

  Such global alignment measures the position coordinates of a plurality of sample shots in a wafer, statistically processes the measured values, calculates wafer shift, magnification, and rotation errors, and takes this error into account to coordinate the wafer. After the correction, the step movement to each shot is performed. Recently, Advanced Global Alignment (AGA: Advanced Global Alignment), which is a global alignment, has been proposed. AGA is a global alignment that relies on the accuracy of an XY stage equipped with a laser interferometer to measure the position of a wafer. Is subjected to signal processing using various parameters to obtain wafer magnification, wafer rotation, and shift amount, and statistical processing such as abnormal value splashing is performed.

  These measurement results and a signal group (hereinafter referred to as “alignment signal”) calculated in the process of deriving the measurement results are transmitted via a communication unit (ADUL: Alignment Data Up Load) 190 shown in FIG. Transferred to the host computer 300. The host computer 300 stores the alignment result and alignment signal such as the shift amount of the wafer 700, the wafer rotation amount, and the wafer magnification obtained by the AGA measurement in the storage device 400.

  The semiconductor manufacturing apparatus 100 includes a communication unit 190 that manages AGA measurement and alignment signal detection and communicates the data to the host computer 300. By using the communication unit 190, data can be exchanged with the host computer 300, and the control unit 180 controls the semiconductor exposure apparatus 100 by receiving the value of the alignment parameter managed on the host computer 300 side. It is possible.

  Next, an alignment signal processing method and alignment parameters in the present embodiment will be described.

  FIG. 5 is a waveform diagram for explaining an example of an alignment signal processing method. The processing method shown in FIG. 5 sets a section A and a section B with respect to the alignment signal AS, performs a filtering process for removing random noise in the section, and then uses a signal AS ′ obtained by first-order differentiation. This is a method for calculating the detection mark position. In this case, for example, the order of the filter that is the processing parameter can be the alignment parameter.

  Another alignment signal processing method is shown in FIG. In the processing method in FIG. 6, for example, S (x) in the measurement direction x with respect to the alignment signal sequence y can be defined as Equation 1. In addition, Formula 1 is equivalent to the case where a = WC−WW / 2 and b = WC + WW / 2 in Formula 24 of Japanese Patent Laid-Open No. 94315.

  When the extreme value of S (x) is the mark center position, as shown in FIG. 6, the window width WW, the window center distance WC, etc., which are processing parameters, can be the alignment parameters. As a specific example, as shown in FIG. 6, S (x) at a certain point x is obtained from Formula 1, and then S (x) is obtained while changing x. The minimum (minimum) value of the curve S (x) or the maximum (maximum) value of 1 / S (x) shown in FIG. 6 is used as the mark position.

  Further, another alignment signal processing method is shown in FIG. In the processing method in FIG. 7, section A and section B are set for the alignment signal AS, polynomial approximation such as Expression 2 is performed on section A and section B, and a mark position is calculated from the obtained polynomial. Is. In this case, the order of the polynomial that is the processing parameter can be the alignment parameter.

  Next, with reference to FIG. 8, optimization of alignment parameters in the first embodiment of the present invention will be described. In the first embodiment, optimization of the processing parameter of the alignment signal processing is shown as the alignment parameter. Here, FIG. 8 is a flowchart for explaining the optimization of the processing parameters of the alignment signal processing.

  First, in step 1010, an alignment waveform is acquired from the communication unit 190. Next, in step 1020, the first waveform and the second waveform are generated.

  FIG. 9 is a detailed flowchart of the first waveform and second waveform generation processing in step 1020. In step 1022, first, when the required detection resolution of the alignment mark is σ [nm] and the pixel pitch of the CCD sensors 660 and 670 is L [nm], the division number N given by Equation 3 is set.

  Next, a first waveform is generated from the acquired alignment waveform (step 1024). The first waveform is a continuous waveform generated by using various interpolation methods from an alignment waveform which is a set of discrete value information having one value for each pixel of the CCD. The interpolation method may be linear interpolation or spline interpolation.

  Next, the first waveform is shifted by k pixels to generate a second waveform Fk (step 1026). Then, it is determined whether or not the generation of all the second waveforms Fk has been completed (step 1028), the value of k is increased until k = N (that is, k ← k + 1), and the second waveform Fk The generation is repeated (step 1029).

  Here, generation of the second waveform Fk in steps 1026 to 1029 will be described in detail with reference to FIG. FIG. 10 is a diagram for explaining the generation process of the second waveform shown in steps 1026 to 1029.

  As shown in FIG. 10A, the acquired alignment waveform yi (0) is divided into N around the pixel i, and the first waveform is yi (−m),..., Yi (−1). ), Yi (0), yi (1),..., Yi (m). However, N = 2m.

  First, in the pixel i, the second waveform F0 (i) is calculated based on the following Equation 4 without shifting the pixel of the first waveform.

  The point to be noted here is that the alignment waveform yi (0) acquired at the pixel i and the second waveform F0 (i) at the pixel i do not necessarily need to match. Hereinafter, the second waveform F0 (i) may be used as an evaluation criterion for parameter optimization in the present embodiment.

  Next, as shown in FIG. 10B, the first waveform yi (−m),..., Yi (−1), yi (0), yi (1),. ) Is shifted by k pixels in the measurement direction, and the processing as shown in the following Expression 5 is performed on the pixel i to generate the second waveform Fk.

  Note that the calculation method of the second waveform Fk differs depending on whether N is an even number or an odd number, and FIG. 10 shows a case where N = 2m (even number). In the case of N = 2m + 1 (odd number), as shown in FIG. 11A, in the pixel i, the second waveform F0 (i) without pixel shifting of the first waveform is expressed by Equation 6 below. Calculate based on

  Next, as shown in FIG. 11B, the first waveform is shifted by k pixels in the measurement direction, and the second waveform Fk at the pixel i is calculated based on Equation 7.

  Thus, the second waveform Fk is generated for the acquired alignment waveform. Here, FIG. 11 is a diagram for explaining another generation process of the second waveform shown in steps 1026 to 1029.

  Returning to FIG. 8, the generated second waveform F0 is selected (step 1030), and signal processing is performed with predetermined processing parameters (step 1040). Until the change of the processing parameter is completed (step 1050), the processing parameter is changed (step 1060), the signal processing is performed with all the processing parameters, and the processing result is stored in the storage device 400. Note that this processing parameter change is performed within a range including both the value of the device setting JOB parameter and the value of the device non-setting JOB parameter.

  Next, in steps 1040 to 1060, the value of k is increased (step 1080) until all the second waveforms Fk are selected (step 1070), and all the processing parameters in all the second waveforms Fk are used. After performing the signal processing, the processing parameters are optimized (step 1090).

  Hereinafter, details of the optimization of the processing parameter in step 1090 will be described. FIG. 12 is a graph showing an example of processing parameter optimization in the present embodiment. FIG. 12A plots the error (deviation from the ideal value) of the signal processing result with respect to the ideal value of the k pixel shift (shift amount) when the filter order in the processing method shown in FIG. 5 is changed. The vertical axis represents the deviation from the ideal value, and the horizontal axis represents the shift amount of the second waveform. Referring to FIG. 12A, the error of the signal processing result varies depending on the filter order. In other words, the sampling error is different.

  FIG. 12B shows, in each filter order, the signal processing error with respect to the ideal pixel shift value by 3K. For example, the minimum order satisfying the required accuracy (in this case, F = 10) is the optimum processing parameter. It can be. 3K is a value that is three times the value of K expressed by Equation 8 below. Note that 3K can be said to be a standard deviation from the case where there is no signal processing error with respect to the ideal pixel shift value (ie, 0).

  If the alignment waveform to be acquired is changed, a processing result as shown in FIG. 13A is also obtained. In this case, as shown in FIG. 13B, the processing parameter (F = 15) having the smallest variation in deviation from the ideal value of the k pixel shift can be selected as the optimum parameter. Here, FIG. 13 is a graph showing an example of optimization of processing parameters in the present embodiment.

  FIG. 14 is a graph showing an example of optimization of processing parameters when the center distance WC of the processing window in the processing method shown in FIG. 6 is changed. FIG. 14A shows an error (deviation from the ideal value) of the signal processing result with respect to the ideal value of the k pixel shift (shift amount) when the center distance WC of the processing window in the processing method shown in FIG. 6 is changed. Is plotted with the deviation from the ideal value on the vertical axis and the shift amount of the second waveform on the horizontal axis.

  FIG. 14B shows the signal processing error with respect to the ideal value of pixel shift at 3K at the center distance WC of each processing window. In this case, WC = 7 where the variation in the error from the ideal value is minimum. Can be selected as the optimum processing parameters.

  FIG. 15 is a graph showing an example of optimization of processing parameters when the degree of the polynomial in the processing method shown in FIG. 7 is changed. FIG. 15A plots an error (deviation from the ideal value) of the signal processing result with respect to the ideal value of the k pixel shift (shift amount) when the order of the polynomial in the processing method shown in FIG. 7 is changed. The vertical axis represents the deviation from the ideal value, and the horizontal axis represents the shift amount of the second waveform.

  FIG. 15B shows, in each polynomial order, the error of the processing signal with respect to the ideal value of pixel shift by 3K. In this case, N = 3 in which the variation of the error from the ideal value is the minimum is optimally processed. Can be selected as a parameter.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, optimization of the processing method itself of alignment signal processing is shown as an alignment parameter. In the present embodiment, it is assumed that the processing parameters in each processing method in FIG. 16 are optimized. Here, FIG. 16 is a flowchart for explaining optimization of the processing method of the alignment signal processing.

  First, an alignment waveform is acquired (step 2010), and a second waveform Fk is generated from the first waveform as in step 1020 described above (step 2020). Thereafter, the second waveform F0 is selected (step 2030), and predetermined signal processing is performed (step 2040). The predetermined signal processing in step 2040 is repeated until the value of k is increased (step 2060) until all the second waveforms Fk are selected (step 2050).

  The processing from step 2040 to 2060 is performed while changing the signal processing method (step 2080) until all the signal processing methods are completed (step 2070). After performing all signal processing on all the second waveforms Fk, optimization of the signal processing method is performed (step 2090).

  Hereinafter, details of the optimization of the signal processing method in step 2090 will be described. FIG. 17 is a graph showing an example of optimization of the signal processing method in the present embodiment. FIG. 17A plots the error (deviation from the ideal value) of the signal processing result with respect to the ideal value of the k pixel shift (shift amount) for each signal processing method, and the vertical axis indicates the deviation from the ideal value. The amount of shift of the second waveform is adopted on the horizontal axis. Referring to FIG. 17A, the error of the signal processing result varies depending on the processing method. In other words, the sampling error is different.

  FIG. 17B shows, in each signal processing method, the error of the signal processing result with respect to the ideal value shifted by k pixels in 3K. For example, the signal processing (in this case P4 in which variation in error from the ideal value is minimal) ) Can be an optimal signal processing method. Note that 3K can be said to be a standard deviation from the case where there is no signal processing error with respect to the ideal pixel shift value (that is, 0).

  Next, a third embodiment of the present invention will be described with reference to FIG. In 3rd Embodiment, the case where 1st Embodiment and 2nd Embodiment are combined is shown. Here, FIG. 18 is a flowchart for explaining optimization of the processing parameters and processing method of the alignment signal processing.

  First, an alignment waveform is acquired (step 3010), the second waveform Fk is generated from the first waveform as in step 1020 described above (step 3020), and then the second waveform F0 is selected (step 3030). .

  Next, signal processing is performed on the second waveform F0 with predetermined processing parameters (step 3040). Until the change of the processing parameter is completed (step 3050), the processing parameter is changed (step 3060), and signal processing is performed with all the processing parameters.

  Next, in the processing from step 3040 to step 3060, until all the second waveforms Fk are selected (step 3070), the value of k is increased (step 3080), and all the processing parameters in all the second waveforms Fk are processed. After performing the signal processing in step 3, the processing parameters in the signal processing are optimized (step 3090).

  The process parameter optimization process from steps 3010 to 3080 is performed while changing the signal processing system (step 3110) until all signal processing systems are completed (step 3100). After the optimization, the signal processing method is optimized (step 3120).

  Next, the application timing of alignment parameter optimization in the first to third embodiments will be described. The optimization of the alignment parameter may be performed on the first wafer of the lot, or may be performed on the wafer extracted in the lot. Further, it may be performed for a plurality of wafers in a plurality of lots, or may be performed for each wafer shot.

  In other words, the communication unit 190 in the semiconductor exposure apparatus 100 confirms whether the wafer 700 is to be optimized by an identifier or an external input formed on the wafer 700 after confirming the loading of the wafer 700 with a sensor (not shown) or the like. to decide. In the case of an optimization target, that is, a wafer whose alignment waveform is to be acquired, the host computer 300 acquires an alignment waveform via the communication unit 190. The above-described optimization processing by shifting the k pixels is performed on the acquired alignment waveform. If the optimal alignment parameter value is not the apparatus setting JOB parameter value, the host computer 300 transmits the optimized alignment parameter to the control unit 180. In response to this, the semiconductor exposure apparatus 100 can change the apparatus setting JOB parameter to the optimum parameter and reflect it in the next JOB.

  In FIG. 1, a certain range including the optimization region of the alignment parameter obtained by a certain semiconductor exposure apparatus 100 is managed by the host computer 300 and used when optimizing the alignment parameter of another semiconductor exposure apparatus 200. This makes it possible to quickly find the optimized region of the semiconductor exposure apparatus 200 without processing the entire area by the semiconductor exposure apparatus 200.

  According to the above embodiments, according to the present invention, a method, an alignment method, an exposure method, and a method for optimizing a signal processing parameter by determining whether or not an alignment parameter set in an exposure apparatus is optimal. An apparatus can be provided. In particular, an optimum alignment signal processing method and processing parameters can be provided even in a situation where WIS, which is a wafer process error, can occur.

  In the present embodiment, when using the exposure apparatus, the alignment parameters can be optimized without consuming a great deal of time and cost when determining the alignment parameters, thereby improving productivity and increasing the cost of ownership (CoO (Cost Of Ownership)). A good exposure system can be achieved.

  Furthermore, in order to determine the optimum alignment parameter in the present embodiment, it is not necessary to perform exposure, and determination may be possible even in an environment without an overlay inspection apparatus, leading to further cost reduction.

  Next, an embodiment of a device manufacturing method using the semiconductor exposure apparatus 100 (exposure system 1) described above will be described with reference to FIGS. FIG. 19 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), a device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique of the present invention using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 4. The assembly process (dicing, bonding), packaging process (chip encapsulation), and the like are performed. Including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

  FIG. 20 is a detailed flowchart of the wafer process in Step 4. In step 1 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus 100 (exposure system 1) to expose a circuit pattern on the mask onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to the device manufacturing method of the present embodiment, it is possible to manufacture a higher quality device than before. Thus, the device manufacturing method using the exposure apparatus 100 (exposure system 1) and the resulting device also constitute one aspect of the present invention.

  As mentioned above, although the preferable Example of this invention was described, it cannot be overemphasized that this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

It is a figure which shows the structure of the exposure system which optimizes the alignment parameter of the semiconductor exposure apparatus in this embodiment. It is a block diagram which shows the whole structure of the semiconductor exposure apparatus shown in FIG. It is a block diagram which shows the main components of the alignment unit shown in FIG. It is a figure which shows the alignment mark and alignment waveform which are shown in FIG. It is a wave form diagram for demonstrating an example of the processing system of an alignment signal. It is a wave form diagram for demonstrating another example of the processing system of an alignment signal. It is a wave form diagram for demonstrating another example of the processing system of an alignment signal. It is a flowchart for demonstrating optimization of the processing parameter of alignment signal processing. FIG. 9 is a detailed flowchart of processing for generating a first waveform and a second waveform in step 1020 shown in FIG. 8. It is a figure for demonstrating the production | generation process of the 2nd waveform shown to step 1026 thru | or 1029 shown in FIG. It is a figure for demonstrating another production | generation process of the 2nd waveform shown to step 1026 thru | or 1029 shown in FIG. 6 is a graph showing an example of optimization of processing parameters when the filter order in the processing method shown in FIG. 5 is changed. 6 is a graph showing an example of optimization of processing parameters when the filter order in the processing method shown in FIG. 5 is changed. It is a graph which shows an example of the optimization of the processing parameter at the time of changing the center distance of the processing window in the processing system shown in FIG. It is a graph which shows an example of the optimization of the processing parameter at the time of changing the order of the polynomial in the processing system shown in FIG. It is a flowchart for demonstrating optimization of the processing system of alignment signal processing. It is a graph which shows an example of the optimization of the signal processing system of step 2090 shown in FIG. It is a flowchart for demonstrating the optimization of the processing parameter and processing system of alignment signal processing. It is a flowchart for demonstrating manufacture of devices (semiconductor chips, such as IC and LSI, LCD, CCD, etc.). FIG. 20 is a detailed flowchart of the wafer process in Step 4 shown in FIG. 19. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure system 100 and 200 Semiconductor exposure apparatus 130 Reticle 150 Projection optical system 160 Wafer chuck 170 Wafer stage 300 Host computer 400 Semiconductor exposure apparatus 500 LAN
600 Alignment unit 610 Light source 620 and 650 Beam splitter 630 Lens 660 and 670 CCD sensor 700 Wafer 710 Alignment mark 720 Position measurement mark

Claims (14)

A method for determining parameters that can be set for signal processing for detecting a position of a mark formed on an object,
Generating a first waveform obtained by forming an optical image of the mark on an image sensor;
Shifting the first waveform by a predetermined shift amount within one pixel of the image sensor to generate a second waveform;
And determining the parameter by performing the signal processing while changing the parameter with respect to the second waveform. The method according to claim 1, wherein the parameter is a processing parameter of the signal processing. The method according to claim 1, wherein the parameter is a processing method of the signal processing. Generating the second waveform comprises:
Dividing an area within one pixel of the image sensor by a division number of 3 or more;
The method according to claim 1, further comprising: shifting the first waveform for each division number divided in the division step. The division number N is σ when the required detection resolution of the mark is L, and the pixel pitch of the image sensor is L,
N> L / σ
5. The method of claim 4, wherein: 6. The method according to claim 5, wherein a required detection resolution of the mark is 50 nm or less. Determining the parameter comprises:
Calculating an error from the ideal value after the signal processing corresponding to the shift amount;
The method according to claim 1, further comprising a step of selecting the parameter having the smallest variation in error from the ideal value calculated in the calculating step. Determining the parameter comprises:
Calculating an error from the ideal value after the signal processing corresponding to the shift amount;
The method according to claim 1, further comprising: selecting the parameter in which a variation in error from the ideal value calculated in the calculating step is equal to or less than a predetermined value. An exposure method for exposing a pattern on the original plate to the target object after aligning the original plate and the target object, wherein the parameter determined by the method according to claim 1 is used for the target object. An exposure method comprising: aligning the original plate and the object to be processed by detecting the position of the formed mark, and then exposing the pattern of the original plate to the object to be processed. 10. The exposure method according to claim 9, wherein the step of determining the parameter is performed with respect to a first object to be processed or extracted from within a lot of the object to be processed. The exposure method according to claim 9, wherein the step of determining the parameter is performed for a plurality of objects to be processed in a plurality of lots of the objects to be processed. The exposure method according to claim 9, wherein the step of determining the parameter is performed for each of a plurality of shots of the object to be processed. An exposure apparatus that exposes a pattern of an original to an object to be processed,
2. An exposure apparatus comprising means for aligning the original plate and the object to be processed by the parameter determining method according to claim 1. Exposing a workpiece using the exposure apparatus according to claim 13;
And performing a predetermined process on the exposed object to be processed.