JP3900562B2 - Exposure equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reticle / mask pattern on each shot region on a wafer as a photosensitive substrate by a step-and-repeat method and a scan method in a manufacturing process of a semiconductor device formed on a substrate using a lithography technique. In particular, the present invention relates to an exposure apparatus that achieves high throughput.
[0002]
[Prior art]
Projection exposure apparatuses are widely used in lithography processes for manufacturing semiconductor elements, display panels, and the like. The projection exposure apparatus projects an image of a pattern formed on a reticle onto a photosensitive substrate (wafer) through a projection optical system.
In such a lithography process, it is necessary to accurately match the circuit pattern formed on the wafer with the image of the circuit pattern to be exposed next. Therefore, the projection exposure apparatus has an alignment mark formed on the substrate. An alignment system is provided for optically detecting. Such an alignment system detects the position of the alignment mark on the stationary coordinate system, and the projection exposure apparatus executes alignment based on the detected position information.
[0003]
Conventionally, in the above-mentioned lithography technology, the resolution can be improved by increasing the NA of the projection lens of the reduction projection exposure apparatus, shortening the exposure wavelength, or adopting a super-resolution technology such as a phase shift method or a modified illumination method. Has been made.
On the other hand, in the alignment technique, the alignment accuracy has been improved by improving the apparatus performance such as vibration control and temperature control of the exposure stage or improvement of aberration of the projection optical system. In particular, due to the progress of design rules (minimum processing dimensions) associated with the high degree of integration of elements, a technique that enables high-precision alignment operations has been required in the exposure process.
[0004]
In the exposure process, alignment is performed based on statistical processing of deviation between the coordinates measured by the sampling shot and the reference coordinate system.
For example, a conversion model based on a linear expression is introduced, and an error component described by the sum of squared sums of differences between measured coordinates and reference coordinates for a field to be exposed on the substrate prior to exposure is first-order. From the simultaneous equations obtained by partial differentiation with each conversion parameter of the conversion model, each conversion parameter of the primary conversion model is determined, and then an alignment lattice (predicted lattice) based on the primary conversion model using the determined conversion parameter as a coefficient. ), And after performing alignment based on the coordinates indicated by the alignment grid, exposure is performed.
[0005]
In the alignment as described above, a highly accurate alignment error measurement technique is required. Conventionally, as such an alignment error, an alignment error mainly generated between fields has been targeted. However, in recent years, the wafer size has been increased, and a plurality of chips are exposed in one shot to improve productivity, so that the size of each exposure field has increased. As a result, the corners of the exposure field have increased. The response to the alignment error has become an important issue. This is affected by positional deviation due to thermal distortion of the wafer. In particular, in a mass production line using a plurality of exposure apparatuses, there is a problem that deterioration of accuracy is unavoidable due to the addition of wrinkles for each exposure apparatus.
For this reason, in addition to the field alignment accuracy, a technique related to the field alignment accuracy is required in the exposure process.
[0006]
Conventionally, the measurement of the field alignment accuracy as described above is performed by one-point measurement in the field in which one point is selected in one exposure field and the alignment error is measured. On the other hand, the alignment accuracy measurement of the in-field components is usually performed by in-field multipoint measurement in which a plurality of points are selected and measured in one exposure field.
[0007]
[Problems to be solved by the invention]
By the way, when performing the in-field multipoint measurement for the in-field component alignment using the current exposure apparatus, the multipoint measurement is performed for each of the exposure fields sampled for measuring the inter-field accuracy. It will be.
[0008]
For example, if a multi-point measurement is performed at five measurement points for all nine sampling exposure fields sampled out of 52 in a wafer having a total of 52 exposure fields, the total number of measurement points is as follows. Is 45 points (5 points) x (9 fields) per sheet, so the time required for measurement increases compared to 9 points when only the overlay error between fields is measured in one point measurement, and the wafer unit This causes a problem that the throughput of the system decreases.
[0009]
Furthermore, the multipoint measurement in the field when one lot is composed of, for example, 25 wafers is also 45 points for each wafer, and this is measured for all 25 wafers. As a result, 1125 points were measured, which caused a significant reduction in throughput.
[0010]
As described above, the conventional technique has a drawback in that the throughput of the lithography process is significantly reduced by increasing the sampling points, and as a result, the cost of the semiconductor device is increased.
[0011]
Accordingly, an object of the present invention is to provide an exposure apparatus capable of solving the above-described problems of the conventional technology and improving the throughput while maintaining the processing accuracy.
[0012]
[Means for Solving the Problems]
The exposure apparatus according to the present invention is proposed in order to achieve the above-mentioned object, and the outline of the exposure apparatus is not to perform multipoint measurement for all the sampled exposure fields but to perform multipoint measurement. The number of fields (hereinafter referred to as a multi-point measurement sampling field) is reduced by at least one or more than the total number of sampling exposure fields, and the remaining exposure fields are measured at one point.
[0013]
This is based on the theoretical basis that “in-field alignment error and inter-field alignment error can be handled independently” and the knowledge obtained by the inventor based on actual measurement using a mechanical sample. To do.
[0014]
That is, according to the study by the present inventor, it was confirmed that the variation in the error of the in-field component (field magnification, rotation) in each exposure field on the wafer is small enough to be practically used. Thereby, magnification and rotation can be represented by magnification and rotation in other exposure fields on the same wafer. That is, it is not necessary to perform multipoint measurement in all the sampled exposure fields, and multipoint measurement can be performed only in a part of the exposure fields.
[0015]
In order to realize the above object based on the above theory and knowledge, an exposure apparatus according to the present invention includes a plurality of exposure fields formed on a substrate corresponding to lithography shots repeated on the substrate in a semiconductor device manufacturing process. In the exposure method in which alignment is performed based on the measurement of a predetermined portion, m (m is 1 ≦ m ≦ n−1) in n exposure fields (n is a natural number of 2 or more) sampled from the substrate. In-field multipoint measurement is performed for (natural number to be satisfied), one in-field measurement is performed for the remaining (nm), and based on the in-field multipoint measurement result of at least one of the m exposure fields. In-field component alignment of a plurality of exposure fields is performed.
In particular, the m is set to 1.
[0016]
According to the above-described exposure apparatus of the present invention, the result of multi-field measurement within the same wafer can be applied to in-field component correction of other exposure fields, so that only one shot or several shots can be applied. In-field multipoint measurement may be performed, whereby the number of multipoint measurement exposure fields is reduced on a substrate (wafer) basis, and throughput is improved.
[0017]
Further, according to another empirical knowledge obtained by actual measurement of another mechanical sample by the present inventor, the difference in the linear error in the field between the wafers belonging to the same lot is small enough to be practically acceptable. That is, from the measured values of field magnification and field rotation, which are linear error components in the field, it was confirmed that these fluctuation amounts in the same lot are negligibly small.
Therefore, according to this result, for a plurality of wafers belonging to the same lot, the error measurement of the in-field component is performed for every other wafer or every several wafers, and this measurement result is applied to each other wafer. Can do.
[0018]
Based on the above knowledge, the exposure apparatus according to the present invention is aligned based on measurement of a predetermined portion of an exposure field formed on the substrate in response to lithography shots repeated on the substrate in the semiconductor device manufacturing process. In the exposure method described above, M (M is 1 ≦ M ≦ N−1) including the first substrate of the lot among all N (N is a natural number of 2 or more) substrates constituting the lot to which the substrate belongs. In-field multipoint measurement is performed on at least one of a plurality of exposure fields sampled on each substrate, and each of the remaining (NM) substrates is subjected to each of the substrates. In-field measurement is performed for a plurality of exposure fields sampled from a plurality of exposure fields, and the exposure field of the substrate is measured based on the multi-point measurement results in the field of the M substrates. In-field component alignment is performed on the field, and the in-field multipoint measurement results made on the M substrates are applied to the other (NM) substrates to align the in-field components in the exposure field. It is characterized by doing.
In particular, the in-field multipoint measurement is performed for all of a plurality of exposure fields sampled for the M substrates.
[0019]
According to the above-described exposure method of the present invention, the number of exposure fields for multipoint measurement is reduced in lot units.
[0020]
Furthermore, the exposure apparatus according to the present invention includes a multipoint measurement wafer setting means for setting at least one multipoint measurement substrate based on a predetermined frequency from all N substrates constituting a lot, and the substrate Sampling field setting means for setting the exposure field to be sampled and setting the number of measurement points for each sampling exposure field, multi-point measurement means for measuring multiple points in the field based on the set number of measurement points, One point measurement means for measuring one point in the field based on the set number of measurement points, In-field component correction amount determination means for determining the in-field component correction amount based on the multipoint measurement result, and other substrates And a correction amount application determining means for determining application of the in-field component correction amount determined to the substrate or field. If so, the in-field component correction amount optimum to be applied to the substrate or field is selected from the already determined correction amounts by the determination of the correction amount application determining means, and thus the accuracy is maintained. At the same time, throughput is improved.
[0021]
Furthermore, the multipoint measurement wafer frequency setting means capable of arbitrarily setting the appearance frequency of the multipoint measurement substrate is provided, and the multipoint measurement wafer frequency setting means is based on the frequency set by the multipoint measurement wafer frequency setting means. In the case where the wafer setting means is configured to set a multipoint measurement substrate, the frequency can be set according to the situation of the lot, thereby realizing high reliability and high throughput.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a functional block diagram of the main part in an embodiment of the exposure apparatus of the present invention. FIG. 2 is a schematic block diagram showing the overall configuration of the exposure apparatus.
First, the overall configuration of the exposure apparatus of the present invention will be described below with reference to FIG. 2, and then the essential parts of the exposure apparatus of the present invention will be described in detail with reference to FIG.
[0023]
As shown in FIG. 2, the exposure apparatus PS of the present invention is roughly divided into an exposure system 80 related to exposure to the wafer 60, a mechanism system 81 for controlling the positions of the wafer 60 and the reticle 59, and alignment of the wafer 60. The system is composed of four systems, that is, an alignment system 82 and a control system 83 that controls the overall operation of the apparatus including these systems. In particular, the present invention is constructed in the control system 83.
[0024]
The exposure system 80 includes an exposure light source 62, a reticle 59 on which an exposure pattern is printed, and a projection optical system 61 including a plurality of combination lenses. A pattern image of the reticle 59 formed in the light beam irradiated by the exposure light beam emitted from the exposure light source 62 is projected and imaged on each shot region on the wafer 60 via the projection optical system 61, and each shot region is formed. Exposure.
[0025]
The mechanism system 81 is a stage drive mechanism 52 that places the wafer 60 and the wafer holder 51 on the wafer stage and moves or rotates them. The mechanism system 81 emits laser light for measurement itself and captures the reflected light from the stage to detect the stage position. The imaging characteristics of the laser interferometer 56, the wafer loader / unloader 55 for loading or unloading the wafer 60 on the stage, the reticle driving mechanism 53 for moving, rotating or tilting the reticle 59, and the projection optical system 61 are controlled. The imaging characteristic control device 54 is configured.
[0026]
If the Z-axis is taken in the optical axis direction of the projection optical system 61 and the orthogonal coordinate system of the two-dimensional plane perpendicular to the Z-axis is taken as the X-axis and Y-axis, the stage drive mechanism 52 is perpendicular to the optical axis of the projection optical system 61. An X stage 52a and a Y stage 52b for positioning the wafer two-dimensionally within a smooth plane, a Z stage 52d for positioning the wafer in the Z direction parallel to the optical axis of the projection optical system 61, and a micro-rotation drive for the wafer It comprises a θ stage 52c.
For example, the X stage 52a is driven in the X direction by the X stage driving device 52e. Similarly, the Y, Z, and θ directions are driven by respective stage driving devices (not shown). Further, as shown in the figure, a tilt motor 52f for tilting the wafer 60 may be provided.
[0027]
A moving mirror composed of a plane mirror having a reflecting surface perpendicular to the X axis is fixed on the upper surface of the wafer stage, and a laser interferometer 56 is disposed so as to face the moving mirror. The laser interferometer 56 includes two X-ray laser interferometers that irradiate the moving mirror with a laser beam along the X-axis, and a Y-axis laser interference that irradiates the moving mirror with a laser beam along the Y-axis. The X coordinate and Y coordinate (stage coordinate system or stationary coordinate system X, Y) of the wafer stage are measured.
[0028]
Further, the rotation angle of the wafer stage is measured based on the difference between the measurement values of the two X-axis laser interferometers. The laser interferometer 56 outputs the measured X coordinate, Y coordinate and rotation angle information as a detection signal 56a. The detection signal 56a is supplied to the control system 83. The control system 83 sends a stage control signal to the X stage driving device 52e and the like to control the positioning operation of the wafer stage.
[0029]
As the wafer weight increases, a machine transfer system such as a robot arm or a conveyor is applied to the wafer loader / unloader 55.
[0030]
The reticle drive mechanism 53 is configured to hold the reticle 59 and move and slightly rotate the reticle 59. Further, the reticle driving mechanism 53 is equipped with a tilt motor 53a for tilting the reticle 59. Although not shown, a three-axis interferometer system similar to that on the wafer side is provided on the reticle side, and a detection signal is supplied to the control system 83, and the control system 83 controls the reticle drive mechanism 53 to drive the reticle. A signal 34b is sent to control the position and angle of the reticle 59.
[0031]
The imaging characteristic control device 54 is attached to the projection optical system 61, and for example, adjusts the distance between predetermined lens groups in the lens groups constituting the projection optical system 61 or the lens cells between the predetermined lens groups. The projection magnification of the projection optical system 61 is adjusted by adjusting the internal pressure. The operation of the imaging characteristic control device 54 is controlled by an imaging characteristic control signal 34 a from the control system 83.
The alignment of the in-field components of the wafer is executed by the imaging characteristic control device 54 and the reticle driving mechanism 53.
[0032]
Next, the alignment system 82 is disposed off-axis on the side surface of the exposure system 80. Illumination light from the illumination light source 63 provided in the alignment system 82 is irradiated to the vicinity of the alignment mark on the wafer through the collimating lens 64, the beam splitter 65, the mirror 66, and the objective lens 67.
A field region is regularly formed on the wafer along a coordinate system (x, y) set on the wafer, and each field region is, for example, in contact with an x-direction scribe line and a y-direction scribe line portion. It is assumed that an X-axis alignment mark and a Y-axis alignment mark are formed.
[0033]
Reflected light from these alignment marks passes through an objective lens 67, a mirror 66, two beam splitters 65 and 68, and a reference index (not shown), and is then condensed on the CCD 70 by an X-axis relay lens 69. The
On the other hand, the light reflected at right angles by the beam splitter 68 is condensed on the CCD 72 via the Y-axis relay lens 71.
The images formed on the CCDs 70 and 72 are images in which the reference index and the alignment mark on the wafer are overlapped. By processing this imaging signal, the amount of positional deviation between the alignment marks on the XY axes and the reference index is reduced. Detected.
[0034]
Next, the operation of the step of positioning each field area (shot area) of the wafer to be exposed and exposing the reticle pattern image to each field area will be described.
First, the wafer 60 to be exposed is loaded on the wafer holder 51, and the amount of displacement is detected by the alignment system 82 for each of a plurality of preset sample fields (sample shots) on the wafer 60.
[0035]
Next, statistical processing (for example, EGA calculation) is performed to minimize the error component calculated from the positional deviation amount, a conversion parameter value is determined, and a linear and virtual primary conversion model (coordinate conversion formula) is obtained. Ask. Then, using this primary conversion model, the arrangement coordinates in the stage coordinate system (X, Y) of each field region are obtained, and an alignment grid table (abbreviated as alignment grid) is organized.
[0036]
The stage is driven based on this alignment grid, the reference point of each field area of the wafer is sequentially positioned at the reference point of the exposure area by the exposure system 80, and then the correction amount that can be applied to that field is used. The alignment correction of the in-field component is executed by adjusting the lens image formation characteristic by the image characteristic control device 54 and / or moving / rotating / tilting the reticle 59 by the reticle driving mechanism 53.
[0037]
The pattern of the reticle 59 is projected and exposed to each field thus aligned. When the projection exposure to each field of the wafer is completed in the above process, the wafer loader / unloader 55 unloads the processed wafer and loads the next wafer onto the stage. Through the above-described steps, exposure processing for all wafers in a lot is performed with high throughput.
[0038]
Next, the main part of the exposure apparatus of the present invention will be described in detail with reference to FIG.
The main part of the exposure apparatus PS of the present invention is the control means 30 shown in FIG. The control system 83 is composed of a Neumann type stored program computer and a plurality of software programs (control means 30) executed by the computer, and the plurality of software programs realize various control functions. It can be handled in the same way as a device as a means to do this. As this computer, a microcomputer, a control computer (FA computer), a personal computer or a workstation can be applied.
[0039]
As shown in FIG. 1, in the computer of the exposure apparatus PS, a CPU 21, a first ROM 22, an EEPROM 23, a RAM 24, and a second ROM 26 are connected to a common bus 25 that is a data backbone.
[0040]
Of the above means, 1 is a multipoint measurement wafer setting means, 2 is a sampling field setting means, 3 is a multipoint measurement means, 4 is an in-field component correction amount determination means, and 5 is an in-field component correction amount storage means. , 6 is a correction amount application determination unit, 7 is a single point measurement unit, 8 is a statistical processing unit, 9 is an alignment grid / transformation model organization / storage unit, and 10 is a multipoint measurement wafer frequency setting unit, both of which are CPU 21 It consists of a software program that can be executed by.
[0041]
In the present embodiment, the multipoint measurement wafer setting means 1 to the in-field component correction amount determination means 4, the correction amount application determination means 6 to the statistical processing means 8, and the multipoint measurement wafer frequency setting means 10 are all first. 1 ROM is stored. The in-field component correction amount storage means 5 and the alignment grid / conversion model organization / storage 9 are stored in a rewritable EEPROM 23.
[0042]
Further, the second ROM 26 stores an overall system control routine 31, a wafer loader / unloader control routine 32, a movement control routine 33, and an in-field component alignment control routine 34, all of which are constituted by software programs that can be executed by the CPU 21. Has been.
[0043]
The multi-point measurement wafer setting means 1 includes M sheets including the first substrate of the lot based on a predetermined frequency out of all N sheets (N is a natural number of 2 or more) constituting the lot. A multipoint measurement substrate (M is a natural number satisfying 1 ≦ M ≦ N−1) is set and supplied to the sampling field setting means 2, and the set multipoint measurement substrate information 1a is used as a correction amount application determination means. 6 is supplied.
At this time, it is preferable that the multipoint measurement substrate is set based on the load detection signal 55 a supplied from the wafer loader / unloader 55.
Alternatively, a configuration in which the multipoint measurement substrate is set based on the load detection signal 55a and the frequency r supplied from the multipoint measurement wafer frequency setting means 10 is also possible.
[0044]
The sampling field setting means 2 sets n (n is a natural number of 2 or more) exposure fields from the substrate as sampling fields, and m (m Is a natural number satisfying 1 ≦ m ≦ n−1) and (n−m) sampling fields for performing one-point measurement in the field, and further, the number of measurement points and the measurement points in the field for multipoint measurement. And the setting result is supplied to the multipoint measuring means 3 and the one-point measuring means 7, and the information 2a relating to the sampling field is supplied to the correction amount application determining means 6.
In addition to a configuration in which the setting is executed based on a pre-installed algorithm, for example, each setting may be executed based on an instruction input or a designation input from the outside.
[0045]
The multipoint measuring means 3 drives the alignment system 82 based on the sampling field for measuring multipoints set by the sampling field setting means 2, the number of measurement points, and the in-field measurement points, and performs multipoint measurement in the field, The multipoint measurement data is supplied to the in-field component correction amount determination means 4. Further, the multi-point measurement data may be configured to supply one point of measurement data at a predetermined in-field measurement point to the one-point measurement means 7. In this case, the measurement data for one point is used for later statistical processing.
[0046]
The in-field component correction amount determination unit 4 determines the correction amount of the in-field component (field magnification, field rotation) of the sampling field based on the multipoint measurement result by the multipoint measurement unit 3. Further, the in-field component correction amount storage means 5 stores and saves the in-field component correction amount determined by the in-field component correction amount determination means 4 for each sampling field, and also stores the stored in-field component correction amount as correction amount information. The correction amount application determination means 6 is supplied as 5a.
[0047]
The correction amount application determination means 6 includes multipoint measurement substrate information 1a supplied from the multipoint measurement wafer setting means 1, sampling exposure field and measurement point number information 2a supplied from the sampling field setting means 2, and a field. Based on the correction amount information 5a of the sampling field supplied from the internal component correction amount storage means 5, the in-field component correction amount to be applied to the field of the wafer is determined, and the correction amount determined to be applied 6a is supplied to the in-field component alignment control routine 34.
[0048]
Therefore, the optimum in-field component correction amount when the in-field component correction amount previously determined in the sampling field field by the correction amount application determining means 6 is applied to another (non-sampling) field of the same wafer. Judgment is made.
Alternatively, regarding the lot, the determination of the optimal in-field component correction amount when applying the in-field component correction amount previously determined using the sampling wafer to other (non-sampling) wafers in the same lot can be performed. Made.
[0049]
On the other hand, the one-point measuring means 7 drives the alignment system 82 for the one-point measurement field set by the sampling field setting means 2 to perform one-point measurement in the field, and the one-point measurement data is statistical processing means. 8 is supplied.
[0050]
The statistical processing means 8 is based on the one-point measurement data supplied from the one-point measurement means 7 or adds the measurement data for the one point supplied from the multi-point measurement means 3 to these one-point measurement data. Statistical processing by dividing the amount of deviation in the absolute coordinate system into components such as shift, rotation, scaling, etc., using a statistical processing method (for example, EGA), calculating parameters for the conversion model, and alignment grid / conversion model organization / storage means 9 is supplied.
[0051]
The alignment grid / transformation model organization / storage unit 9 organizes and stores an alignment grid as a virtual array based on the parameters supplied from the statistical processing unit 8. Alternatively, the primary conversion model is organized and stored.
The stored alignment grid or transformation model is accessed by the movement control routine 33.
[0052]
The multi-point measurement wafer frequency setting means 10 can arbitrarily set the appearance frequency of the multi-point measurement substrate, and the user sets and inputs an arbitrary desired appearance frequency r according to the situation of the lot. Can do. The input of setting the appearance frequency can be realized by an input device such as a keyboard or a mouse (not shown).
The multipoint measurement wafer frequency setting means 10 supplies the set frequency r to the multipoint measurement wafer setting means 1. The multipoint measurement wafer setting means 1 sets the multipoint measurement substrate as described above based on the frequency r.
[0053]
The wafer loader / unloader control routine 32 sends a wafer load control signal 32a to the wafer loader / unloader 55 to control loading / unloading of the wafer. The wafer loader / unloader 55 sends a load detection signal 55a to the multipoint measurement wafer setting means 1 every time a wafer is loaded.
[0054]
The movement control routine 33 accesses the alignment grating or the conversion model stored in the alignment grating / conversion model organization / storage means 9 and further determines the stage movement amount based on the detection signal 56 a supplied from the laser interferometer 56. The stage control signal 33a is sent to the stage drive mechanism 52, thereby controlling the stage movement.
[0055]
The in-field component alignment control routine 34 drives the image formation characteristic control signal 34a to the image formation characteristic control device 54 and / or the reticle drive to the reticle drive mechanism 53 based on the correction amount 6a supplied from the correction amount application determination means 6. A control signal 34b is sent to control the in-field component alignment.
[0056]
The overall system control routine 31 manages various types of control related to the entire system.
[0057]
In addition to the EEPROM 23 as shown in the figure, the data is recorded and stored in a nonvolatile memory such as an SRAM or a flash memory, an HDD, or a removable recording medium (floppy disk, removable hard disk, optical disk or magneto-optical disk). Can be configured to record and save.
[0058]
Next, an example of lithography processing by the exposure apparatus of the present invention will be described below.
FIG. 3 is an explanatory diagram of an operation for reducing the number of multipoint measurement fields in units of substrates as an example of lithography processing by the exposure apparatus of the present invention.
As shown in the figure, this lithography processing uses nine fields F11 to F19 out of 52 fields on the wafer U1 as sampling fields, and among these nine sampling fields F11 to F19, in the center. Only the field F11 is used as a sampling field for multipoint measurement (indicated by M in the figure), and 5 points in the field are measured, and the remaining 8 fields F12 to F19 are designated for single point measurement (indicated by S in the figure). As a result, one point measurement in the field is performed.
[0059]
Then, the in-field component correction amount determined based on the in-field five-point measurement for the central field F11 is applied not only to each sampling field F11 but also to all 52 fields on the wafer U11. Align. For example, this correction amount is also applied to fields F120 and F160 indicated by dotted lines in the drawing. As described above, this is based on the fact that the fluctuation amount of the linear error component in the field (field magnification and field rotation) between different fields on the same wafer is negligibly small according to the actually measured value.
[0060]
As a result, the total number of measurement points made on the wafer U1 is 5 points for the field F11 and 13 points in total, one point for each of the remaining eight fields F12 to F19. With only such a small measurement of 13 points, data for obtaining the alignment grid of the wafer U1 and data for obtaining in-field component correction amounts applicable to all the fields on the wafer U1 can be obtained. .
[0061]
Compared with the conventional case of measuring 45 points, 5 points for each of all 9 sampling fields, a significant reduction of about 71% can be achieved.
Thus, in the present embodiment, the time required for measurement can be greatly shortened by reducing the number of multipoint measurement fields in units of substrates.
[0062]
FIG. 4 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIG.
First, when a wafer is loaded (step S101), the stage is driven to move to the sampling field (step S102).
Next, it is confirmed by the sampling field setting means 2 whether or not the sampling field is a multipoint measurement sampling field (step S103). If it is a multipoint measurement sampling field, the multipoint measurement means 3 performs multipoint measurement. (Step S104).
[0063]
Based on the multipoint measurement result, the in-field component correction amount determining means 4 determines the in-field component correction amount (step S105), and is stored by the in-field component correction amount storage means 5 (step S106). The above operation is repeated until the end of all sampling fields (step S108).
[0064]
On the other hand, when it is confirmed in step S103 that the sampling field is not a multi-point measurement sampling field, one-point measurement is performed by the one-point measuring means 7 as a sampling field for one-point measurement (step S107). The process proceeds to step S108.
[0065]
Next, the statistical processing means 8 performs statistical processing based on one point data measured in each sampling field (this includes one point data extracted from multiple points measured in the multipoint measurement sampling field). The conversion parameters are calculated (step S109), and the alignment grid or conversion model of the wafer is knitted and stored by the alignment grid / conversion model knitting / storing means 9 (step S110).
[0066]
When the measurement is completed, the exposure process starts. The movement control routine 33 fetches the alignment grid or conversion model of the loaded wafer from the alignment grid / conversion model organization / storage means 9 and refers to these to each field (sampling field, non-sampling field all on this wafer). (Step S111). This is actually a relative movement for driving the stage side on which the wafer is mounted with respect to the optical system.
[0067]
Next, the in-field component alignment control routine 34 applies the determined and stored correction amount to this field to execute in-field component alignment (step S112).
[0068]
As described above, when the alignment of this field is completed, the preparation for exposure is completed and the exposure is executed (step S113).
The above process is repeated for all the fields on the wafer (step S114), and when the exposure is completed for all the fields, the operation ends.
[0069]
FIG. 5 is an explanatory diagram of another operational example in which the number of multi-point measurement fields is reduced in units of substrates by the exposure apparatus of the present invention.
As shown in the figure, this lithography processing uses nine fields F21 to F29 among the 52 fields on the wafer U2 as sampling fields, and among these nine sampling fields F21 to F29, field F21. , F22, F24, F26, and F28 are used as multi-point measurement sampling fields (indicated by M in the figure), and five points in the field are measured, and the remaining four fields F23, F25, F27, and F29 are set to 1 One point measurement in the field is performed as a point measurement sampling field (indicated by S in the figure).
[0070]
Then, five sets of in-field component correction amounts determined based on the five in-field measurements to the five multi-point measurement sampling fields are used as a plurality of not only the multi-point measurement sampling fields but also the surroundings. In-field component alignment of all 52 fields on the wafer U2 is performed by applying to a single field measurement sampling field and a non-sampling field. For example, the in-field component correction amount based on the five-point measurement in the field F22 is applied to the field F220 indicated by a dotted line in the drawing. Similarly, the in-field component correction amount based on the five-point measurement in the field F26 is applied to the field F260.
Further, an in-field component correction amount based on the five-point measurement in the nearest multipoint measurement sampling field F28 is applied to the field F290 adjacent to the one-point measurement sampling field F29.
[0071]
As a result, the total number of measurement points made on the wafer U2 is 29 points, 5 points for each of the 5 multipoint measurement sampling fields and 1 point for each of the remaining 4 fields. Only by measuring these 29 points, data for obtaining the alignment grid of the wafer U2 and data for obtaining in-field component correction amounts applicable to all the fields on the wafer U2 can be obtained.
This embodiment is particularly effective in the case where the influence of positional deviation due to thermal distortion of the wafer is eliminated.
[0072]
FIG. 6 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIG.
First, when a wafer is loaded (step S201), the stage is driven to move to the sampling field (step S202).
Next, it is confirmed by the sampling field setting means 2 whether or not the sampling field is a multipoint measurement sampling field (step S203). If it is a multipoint measurement sampling field, the multipoint measurement means 3 performs multipoint measurement. (Step S204).
[0073]
Based on the multipoint measurement result, the in-field component correction amount determination means 4 determines the in-field component correction amount for each multipoint measurement sampling field (step S205) and stores it in the in-field component correction amount storage means 5 (step S205). Step S206). The above operation is repeated until the end of all sampling fields (step S208).
[0074]
On the other hand, when it is confirmed in step S203 that the sampling field is not a multi-point measurement sampling field, one-point measurement is performed by the one-point measuring means 7 as a sampling field for one-point measurement (step S207). The process proceeds to step S208.
[0075]
Next, the statistical processing means 8 performs statistical processing based on one point data measured in each sampling field (this includes one point data extracted from multiple points measured in the multipoint measurement sampling field). The conversion parameters are calculated (step S209), and the alignment grid or conversion model of this wafer is knitted and stored by the alignment grid / conversion model knitting / storing means 9 (step S210).
[0076]
When the measurement is completed, the exposure process starts. The movement control routine 33 fetches the alignment grid or conversion model of the loaded wafer from the alignment grid / conversion model organization / storage means 9 and refers to these to each field (sampling field, non-sampling field all on this wafer). (Step S211).
[0077]
Next, the correction amount application determination means 6 selects and determines a correction amount to be applied to the field (that is, diverted from another field of the same wafer) from among the in-field component correction amounts for each multipoint measurement sampling field. (Step S212), the in-field component alignment control routine 34 applies the selected correction amount to this field, and executes in-field component alignment (step S213).
[0078]
As described above, when the alignment of this field is completed, preparation for exposure is completed, and exposure to this field is executed (step S214).
The above process is repeated for all the fields on the wafer (step S1215), and when the exposure is completed for all the fields, the operation ends.
[0079]
FIG. 7 is an explanatory diagram of an operation for reducing the number of multipoint measurement fields in units of lots as an example of lithography processing by the exposure apparatus of the present invention.
As shown in the figure, this lithography process is composed of four wafers U11 to U14 in one lot, and only the first wafer U11 is used as a sampling wafer for multipoint measurement, and among the 52 fields on this wafer U11, Of the nine sampled fields F111 to F119, only the central field F111 is measured in the field, and the remaining eight fields F112 to F119 are measured in the field. Thereafter, for the remaining three wafers U12 to U14, for example, in the wafer U12, one point measurement in the field is performed in all nine fields F121 to F129. Wafers U13 and U14 are similarly processed.
[0080]
Then, the in-field component correction amount determined based on the in-field five-point measurement for the central field F111 is applied to the exposure fields F111 to F119 of the first wafer U11 to perform in-field component alignment. The correction amount is applied to all 52 fields on the wafer U11 to perform in-field component alignment. For example, this correction amount is also applied to the fields F1110 and F1120 indicated by dotted lines in the drawing.
[0081]
In addition, the in-field component correction amount determined based on the in-field five-point measurement on the field F111 of the first wafer U11 is applied to all the fields on the subsequent three wafers U12 to U14. In-field component alignment is performed. For example, this correction amount is also applied to the field F1280 of the wafer U12, the field F1360 of the wafer U13, and the field F1490 of the wafer U14 shown by dotted lines in the drawing.
As described above, this is based on the actual measurement result that the difference (variation) in the linear error in the field between the wafers belonging to the same lot is small enough to be ignored.
[0082]
Thus, by reducing the number of multipoint measurement fields in both the lot unit and the substrate unit, the time required for measurement can be greatly shortened compared to the conventional method.
[0083]
FIG. 8 is an explanatory diagram of another operational example in which the number of multipoint measurement fields is reduced in lot units by the exposure apparatus of the present invention.
As shown in the figure, in this lithography process, one lot is composed of six wafers U21 to U26, and sampling wafers for multipoint measurement are set every three sheets including the first wafer U21. Therefore, the sampling wafers for multipoint measurement in this lot are U21 and U24.
[0084]
First, of the 52 fields on the wafer U11, 9 fields F211 to F219 are sampled. Then, among these 9 fields F211 to F219, only the central field F211 is measured, and the remaining fields are left. One field measurement is performed in the eight fields F212 to F219. For the subsequent two wafers U22 and U23, for example, in the wafer U22, one point measurement in the field is performed in all nine fields F221 to F229. The same applies to the wafer U23.
[0085]
In addition, the in-field component correction amount determined based on the in-field five-point measurement for the central field F211 is applied to the fields F211 to F219 of the first wafer U21 to perform in-field component alignment. This correction amount is applied to all 52 fields on the wafer U21 to perform in-field component alignment. For example, this correction amount is also applied to the field F2120 indicated by the dotted line in the drawing.
[0086]
In addition, the in-field component correction amount determined based on the in-field five-point measurement on the field F211 of the first wafer U21 is applied to all the fields on the subsequent two wafers U22 and U23. In-field component alignment is performed. For example, this correction amount is also applied to the field F2280 of the wafer U22, the field F2360 of the wafer U23, and the like indicated by dotted lines in the drawing.
[0087]
When the three wafers U21 to U23 are processed in this way, the loaded wafer U24 is a sampling wafer for multipoint measurement, and therefore, out of 52 fields on the wafer U24, nine fields F241 are included. ... F249 are sampled, and among the nine fields F241 to F249, five points in the field are measured for only the central field F241, and one point in the field is measured for the remaining eight fields F242 to F249. For the subsequent two wafers U25 and U26, for example, in the wafer U25, one point measurement in the field is performed in all nine fields F251 to F259. The same applies to the wafer U26.
[0088]
Then, the in-field component correction amount is determined based on the in-field five-point measurement for the center field F241. Here, the previously stored in-field component correction amount is updated.
This updated in-field component correction amount is applied to each field F241 to F249 of the wafer U24 to perform in-field component alignment, and this correction amount is applied to all 52 fields on the wafer U24 (in the figure, (Including field F2420 indicated by a dotted line), in-field component alignment is performed.
In addition, this in-field component correction amount is applied to all the fields on the subsequent two wafers U25 and U26 (including the fields F2580 and F2690 indicated by dotted lines in the figure) to perform the in-field component alignment. To do.
[0089]
Therefore, for a plurality of wafers belonging to the same lot, an in-field component alignment correction amount of the field is determined for every other wafer or every several wafers, and this correction amount is then determined for each of the other wafers belonging to the same lot. By applying to the in-field component alignment of this field, the measurement and calculation can be omitted, and the throughput is improved.
[0090]
FIG. 9 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIGS.
First, when a wafer is loaded (step S301), the multipoint measurement wafer setting means checks whether the wafer is the first wafer of a lot or a wafer for multipoint measurement (step S302). In the case of the above wafer and the wafer for multipoint measurement, the stage is driven and moves to the sampling field (step S303).
[0091]
Next, when the sampling field setting means 2 confirms that the sampling field is a multipoint measurement sampling field (step S304), multipoint measurement is performed by the multipoint measurement means 3 (step S305), and the in-field component correction is performed. The in-field component correction amount is determined by the amount determining means 4 (step S306), the correction amount is stored by the in-field component correction amount storage means 5 (step S307), and the process proceeds to step S309.
[0092]
If it is confirmed in step S304 that the sampling field is a one-point measurement sampling field, one-point measurement is performed by the one-point measurement means 7 (step S308), and the process proceeds to step S309. In step S309, the above is repeated until the end of all sampling fields. When all sampling fields are completed, the process proceeds to step S313.
[0093]
On the other hand, when it is confirmed in step S302 that the wafer is not the first wafer of the lot or the wafer for multipoint measurement, the wafer is moved to the sampling field by driving the stage as being a single-point measurement wafer (step S310). One-point measurement is performed by the one-point measuring means 7 (step S311), and this process is repeated until all sampling fields are completed (step S312). When all sampling fields are completed, the process proceeds to step S313.
[0094]
In step S313, statistical processing is performed for each wafer based on one-point data measured in each sampling field (this includes one-point data extracted from multiple points measured in the multi-point measurement sampling field). The means 8 performs statistical processing to calculate conversion parameters (step S313), and the alignment lattice / conversion model organization / storage means 9 organizes and stores the alignment lattice or conversion model for each wafer (step S314). With the above processing, each time a wafer is loaded, an alignment grid or conversion model corresponding to each wafer is formed.
[0095]
When the measurement is completed, the exposure process starts. The movement control routine 33 fetches the alignment grid or conversion model corresponding to the currently loaded wafer from the alignment grid / conversion model organization / storage means 9, and refers to these fields to determine each field (sampling field, non-display field) on this wafer. Move to all sampling fields) (step S315). This is actually a relative movement for driving the stage side on which the wafer is mounted with respect to the optical system.
[0096]
Next, the correction amount application determining means 6 determines the in-field component correction amount to be applied to the wafer (step S316), and the in-field component alignment control routine 34 applies the determined correction amount to all the fields on the wafer. Then, in-field component alignment is executed (step S317).
[0097]
As described above, when the field alignment on the wafer is completed, the preparation for exposure is completed, and the field is exposed (step S318).
The above process is repeated for all fields on the wafer (step S319). When exposure is completed for all fields, the subsequent lot is loaded and the above operation is repeated to complete exposure of all wafers in the lot (step S319). S320) The operation ends.
[0098]
FIG. 10 is an explanatory diagram of another operation for reducing the number of multipoint measurement fields in units of lots as an example of lithography processing by the exposure apparatus of the present invention.
As shown in the figure, this lithography process is composed of four wafers U31 to U34 in one lot, and only the first wafer U31 is used as a sampling wafer for multipoint measurement. Of the 52 fields on this wafer U31, In-field five-point measurement is performed for all the nine sampled fields F311 to F319.
[0099]
Thereafter, for the remaining three wafers U32 to U34, for example, in the wafer U32, one point measurement in the field is performed in all nine fields F321 to F329. The same applies to the wafers U33 and U34.
[0100]
Then, by applying a total of nine sets of in-field component correction amounts determined based on five in-field measurements on the sampled fields F311 to F319 on the wafer U31 to adjacent fields, the wafer U31. In-field component alignment is performed for all the above 52 fields. As described above, the correction amount determined in the adjacent sampling field is applied to the non-sampling field (for example, the fields F3110 and F3120 indicated by dotted lines in the drawing).
[0101]
In addition, a total of nine sets of in-field component correction amounts determined on the basis of five in-field measurements on the sampling fields F311 to F319 of the first wafer U31 are obtained on the subsequent three wafers U32 to U34. By applying this method to each corresponding field and adjacent fields, in-field component alignment of all fields is performed. For example, the in-field component correction amount determined in the sampling field F318 of the wafer U31 is applied to the exposure field F3280 of the wafer U32 indicated by a dotted line in the drawing. The in-field component correction amount determined in the sampling field F316 of the wafer U31 is applied to the exposure field F3360 of the wafer U33. Further, the in-field component correction amount determined in the sampling field F319 of the wafer U31 is applied to the exposure field F3490 of the wafer U34.
[0102]
According to the above, by using a plurality of five-point measurement fields, sufficient alignment accuracy is ensured even when there is a large variation in the field component error in fields at different positions on the wafer, and the number of multi-point measurements can be increased. By reducing the number of multipoint measurement fields in both the lot unit and the substrate unit, the time required for measurement can be greatly shortened as compared with the conventional method.
[0103]
FIG. 11 is an explanatory diagram of still another operation example in which the number of multi-point measurement fields is reduced in lot units by the exposure apparatus of the present invention.
As shown in the figure, in this lithography process, one lot is composed of six wafers U41 to U46, and sampling wafers for multipoint measurement are set every three sheets including the first wafer U41. Therefore, the sampling wafers for multipoint measurement in this lot are U41 and U44.
[0104]
First, of the 52 fields on the wafer U41, nine fields F411 to F419 are sampled, and then five points in the field are measured for all the nine fields F411 to F419. Thereafter, with respect to the remaining two wafers U42 to U43, for example, in the wafer U42, one-point measurement is performed in all nine fields F421 to F429. The same applies to the wafer U43.
The operations below this are in accordance with the operation performed in FIG.
[0105]
When the three wafers U41 to U43 are processed in this way, the wafer U44 loaded subsequently is a sampling wafer for multipoint measurement as described above, and therefore, multipoint measurement is performed here. The in-field component correction amount by the wafer U44 is determined. Accordingly, at this stage, the in-field component correction amount by the wafer U41 is updated.
The operations below this are in accordance with the above operation.
[0106]
FIG. 12 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIGS.
First, when a wafer is loaded (step S401), it is confirmed by the multipoint measurement wafer setting means whether it is the first wafer of a lot or a wafer for multipoint measurement (step S402). If the wafer is a wafer for multipoint measurement or a wafer for multipoint measurement, the stage is driven to move to the sampling field (step S403).
[0107]
In the present embodiment, since multipoint measurement is performed for all sampling fields of a wafer for multipoint measurement, multipoint measurement is immediately performed by the multipoint measurement means 3 (step S404), and intra-field component correction is performed. The amount determination means 4 determines the in-field component correction amount for each sampling field (step S405), and the correction amount for each sampling field is stored in the in-field component correction amount storage means 5 (step S406). The above is repeated until the end of all sampling fields (step S407).
[0108]
On the other hand, if it is confirmed in step S402 that the current wafer is not the first wafer in the lot or the wafer for multipoint measurement, it is determined that it is a single point measurement wafer and the stage is driven to the sampling field. It moves (step S408), one point measurement is performed by the one point measuring means 7 (step S409), and this process is repeated until the end of all sampling fields of this wafer (step S410).
[0109]
Then, for each wafer, based on one point data measured in each sampling field (this includes one point data extracted from multiple points measured in the multipoint measurement sampling field), the statistical processing means 8 Performs statistical processing to calculate conversion parameters (step S411), and the alignment grid or conversion model for each wafer is organized and stored by the alignment grid / conversion model organization / storage means 9 (step S412). With the above processing, each time a wafer is loaded, an alignment grid or conversion model corresponding to each wafer is formed.
[0110]
When the measurement is completed, the exposure process starts.
The movement control routine 33 fetches the alignment grid or conversion model corresponding to the currently loaded wafer from the alignment grid / conversion model organization / storage means 9, and refers to these fields to determine each field (sampling field, non-display field) on this wafer. Move to all sampling fields) (step S413). This is actually a relative movement for driving the stage side on which the wafer is mounted with respect to the optical system.
[0111]
Next, the correction amount application determining means 6 applies the field on the wafer (that is, diverts another field of the same wafer, diverts the same position field of another wafer or the field of a different position of another wafer). The in-field component correction amount is selected and determined (step S414), and the in-field component alignment control routine 34 applies the selected and determined correction amount to the field on the wafer to execute in-field component alignment. (Step S415).
[0112]
As described above, when the field alignment on the wafer is completed, preparation for exposure is completed, and thus exposure to the field is executed (step S416).
The above process is repeated for all fields on the wafer (step S417). When exposure is completed for all fields, the subsequent lot is loaded and the above operation is repeated to complete exposure of all wafers in the lot (step S417). S418) The operation ends.
[0113]
FIG. 13 is an operation flowchart of an embodiment of the correction amount application determination means 6 incorporated in the exposure apparatus of the present invention.
When the correction amount application determination means 6 starts operating, it is first confirmed based on the information 1a whether this wafer is a multipoint measurement wafer set by the multipoint measurement wafer setting means 1 (step S4141). If this wafer is a multipoint measurement wafer, it is determined that the correction amount measured and determined for this wafer is to be applied (step S4143), and the process returns.
On the other hand, if this wafer is not a multipoint measurement wafer, it is determined that the correction amount measured and determined by the multipoint measurement wafer processed before this wafer is applied to this wafer (step S4142). Return.
[0114]
As described above, the exposure apparatus according to the present invention applies the correction amount of the in-field component already determined in another exposure field on the same substrate when aligning the in-field component with respect to the exposure field on the same substrate. Or, when performing in-field component alignment for each substrate belonging to the same lot, the correction amount of the in-field component already determined by any other substrate including the first substrate is applied as it is. Thus, it is possible to reduce the number of multi-point measurement exposure fields at least in units of substrates (wafers) or lots.
[0115]
In the present invention, it is possible to select the multipoint measurement field from any position on the substrate. However, it is desirable to select the field with symmetry in order to suppress the influence of variation for each exposure field. In particular, when the number of sampling fields for performing multipoint measurement is one, it is preferable to select this sampling field from the center of the substrate, thereby minimizing the influence of thermal deformation of the wafer. .
[0116]
The alignment optical system for mark detection is not limited to the off-axis type as described above. For example, the alignment optical system is a TTL (through-the-lens) on-axis system that shares the projection optical system. There is no problem. This is advantageous because the baseline error management can be omitted.
[0117]
Further, the present invention is not limited to the above-described embodiments. For example, the layout and total number of exposure fields on the wafer, the field size, the layout and total number of sampling fields, the number and layout of measurement points in the field, and the like. Implementation is possible regardless of the case.
[0118]
【The invention's effect】
In the exposure apparatus according to claim 1 of the present invention, m (m is a natural number satisfying 1 ≦ m ≦ n−1) in n exposure fields (n is a natural number of 2 or more) sampled from the substrate. In-field multipoint measurement is performed, the remaining (nm) points are measured in one field, and a plurality of exposures are performed based on the in-field multipoint measurement results of at least one of the m exposure fields. Since the configuration is such that the in-field component alignment of the field is performed, the number of exposure fields for multipoint measurement can be reduced in units of wafers, and throughput can be improved and productivity can be improved.
[0119]
The exposure apparatus according to claim 2 of the present invention performs in-field multipoint measurement only for one exposure field per wafer processing, and based on the measurement result, in-field components of all exposure fields on the wafer. Since the alignment is performed, it is possible to further improve the throughput of the lithography process and shorten the processing time.
[0120]
Of the present invention other The exposure apparatus has M (M satisfies 1 ≦ M ≦ N−1) including the first substrate of the lot among all N (N is a natural number of 2 or more) substrates constituting the lot to which the substrate belongs. In-field multipoint measurement is performed on at least one of a plurality of exposure fields sampled on each of the (natural number) substrates, and the remaining (NM) substrates are sampled from each of the substrates. In-field measurement is performed for a plurality of exposure fields, and in-field component alignment is performed on the exposure field of the substrates based on the multi-point measurement results in the fields of the M substrates. Since the in-field multipoint measurement result made on one substrate is applied to the other (NM) substrates, the in-field component alignment of the exposure field is performed. The number of exposure field for measuring multiple points can be reduced in batches, thus it is possible to greatly improve the productivity by improving the throughput of the lithographic process.
[0121]
Of the present invention Yet another Since the exposure apparatus is configured to perform in-field multipoint measurement for all of a plurality of exposure fields sampled on M substrates, even if there is a large variation in in-field component errors in exposure fields at different positions on the wafer. In addition, sufficient alignment accuracy can be ensured, and the number of multipoint measurements can be reduced in lot units to improve the lithography process throughput.
[0122]
Of the present invention Yet another An exposure apparatus includes: a multipoint measurement wafer setting means for setting at least one multipoint measurement substrate based on a predetermined frequency out of all N substrates constituting a lot; and an exposure field to be sampled on the substrate And a sampling field setting means for setting the number of measurement points for each sampling exposure field, a multi-point measurement means and a single-point measurement means for performing multipoint measurement in the field or one point based on the number of measurement points set in this way And an intra-field component correction amount determining means for determining an intra-field component correction amount based on the multipoint measurement result, and the intra-field component correction amount previously determined using another substrate to the substrate or the field. Correction amount application determining means for determining application, and so on by the determination of the correction amount application determining means. The optimum field component correction amount to apply the substrate or and the field, already can be selected from the determined correction amount, thus can maintain the accuracy to achieve an improvement in throughput.
[0123]
Of the present invention Yet another The exposure apparatus includes a multi-point measurement wafer frequency setting unit capable of arbitrarily setting the appearance frequency of the multi-point measurement substrate, and the multi-point measurement wafer setting unit is configured by the multi-point measurement wafer frequency setting unit. Since the multipoint measurement substrate is set based on the set frequency, it becomes possible for the user to arbitrarily set the desired frequency according to the situation of the lot. High throughput can be realized.
[0124]
As described above, the exposure apparatus of the present invention realizes alignment correction with practically sufficient accuracy while reducing the number of multipoint measurements in wafer units or lot units. In this way, by reducing the number of samplings without losing the alignment accuracy (correction accuracy), the total time required for the lithography process is shortened along with TAT improvement, thereby improving reliability, cost reduction, and throughput improvement in semiconductor device manufacturing. It contributes greatly.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of essential parts in an embodiment of an exposure apparatus of the present invention.
FIG. 2 is a schematic block diagram showing the overall configuration of an embodiment of the exposure apparatus of the present invention.
FIG. 3 is an explanatory diagram of an operation for reducing the number of multi-point measurement fields in units of substrates as an example of lithography processing by the exposure apparatus of the present invention.
4 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIG.
FIG. 5 is an explanatory diagram of another operational example for reducing the number of multi-point measurement fields in units of substrates by the exposure apparatus of the present invention.
6 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIG.
FIG. 7 is an explanatory diagram of an operation for reducing the number of multi-point measurement fields in units of lots as an example of lithography processing by the exposure apparatus of the present invention.
FIG. 8 is an explanatory diagram of another operational example for reducing the number of multi-point measurement fields in units of lots by the exposure apparatus of the present invention.
9 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIGS. 7 and 8. FIG.
FIG. 10 is an explanatory diagram of another operation example in which the number of multi-point measurement fields is reduced in lot units as an example of lithography processing by the exposure apparatus of the present invention.
FIG. 11 is an explanatory diagram of still another operation example in which the number of multi-point measurement fields is reduced in lot units by the exposure apparatus of the present invention.
12 is an operation flowchart of the exposure apparatus of the present invention in the operation example of FIGS. 10 and 11. FIG.
FIG. 13 is an operation flowchart of an embodiment of a correction amount application determination unit incorporated in the exposure apparatus of the present invention.
[Explanation of symbols]
1 ... Multipoint measurement wafer setting means, 1a ... Multipoint measurement wafer information, 2 ... Sampling field setting means, 2a ... Sampling field information, 3 ... Multipoint measurement means, 4 ... In-field components Correction amount determination means, 5... In-field component correction amount storage means, 5a... Correction amount, 6... Correction amount application determination means, 6a. ... Statistical processing means 9... Alignment grid / transformation model organization / storage means 10... Multi-point measurement wafer frequency setting means 21... CPU 22... First ROM 23. 25 ...... Common bus 26 ... Second ROM 30 ... Control means 31 ... Whole system control routine 32 ... Wafer loader / unloader control routine 32a ... Wafer load control 33... Movement control routine, 33 a... Stage control signal, 34. In-field component alignment control routine, 34 a... Imaging characteristic control signal, 34 b .. Reticle drive control signal, 52. 53: Reticle drive mechanism, 54: Lens imaging characteristic control device, 55: Wafer loader / unloader, 55a: Load detection signal, 56: Laser interferometer, 56a: Detection signal, PS: Exposure Device, r ... frequency.

Claims (2)

An exposure apparatus in which alignment is performed based on measurement of a predetermined portion of an exposure field formed on the substrate corresponding to a lithography shot repeated on the substrate in a semiconductor device manufacturing process,
Among n exposure fields sampled from the substrate (n is a natural number of 2 or more), m (m is a natural number satisfying 1 ≦ m ≦ n−1) are measured in the field and remain (n -M) perform one-point measurement in the field, and perform in-field component alignment of the plurality of exposure fields based on the multi-point measurement result in the field of at least one of the m exposure fields, and at least An exposure apparatus characterized by performing inter-field alignment of the plurality of exposure fields based on a result of one point measurement in the field.   2. The exposure apparatus according to claim 1, wherein m is 1.

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