KR100950488B1 - Exposure device - Google Patents

Abstract

The exposure apparatus exposes each of the plurality of regions arranged on the substrate. The exposure apparatus measures i) the position of the alignment mark formed in each of at least two regions of the plurality of regions under a plurality of measurement conditions in the measurement unit, and ii) under the plurality of measurement conditions, Calculating a feature value of the signal obtained with respect to each, and iii) a value approximating the feature value corresponding to the design position with the coordinates of the design position of the alignment mark with respect to each of the plurality of measurement conditions. Calculating a coefficient of a conversion equation that is converted into a value, and replacing the measured position with the feature value to convert the coordinate of the design position into a value approximating the coordinate of the measured position corresponding to the design position. And a processing unit configured to formulate the transform equation from the coordinate transform equation.

Exposure apparatus, alignment mark, semiconductor device, projection optical system

Description

Exposure equipment {EXPOSURE APPARATUS}

The present invention relates to an exposure apparatus for exposing a substrate to radiant energy.

In the exposure apparatus for semiconductor device manufacture, it is calculated | required that the circuit pattern from a reticle surface can be projected and exposed to a higher resolution on a board | substrate surface with the refinement | miniaturization and density of a circuit. The projection resolution of the circuit pattern depends on the numerical aperture NA of the projection optical system and the exposure wavelength. For this reason, as a method of high resolution, the method which enlarges NA of a projection optical system and the method which shortens an exposure wavelength is employ | adopted. In the method of shortening the exposure wavelength, the wavelength of the exposure light source shifts from g line to i line and also from i line to oscillation wavelength of the excimer laser. Exposure apparatuses having excimer lasers having oscillation wavelengths of 248 nm and 193 nm have already been put into practical use. At present, an exposure method using EUV (Extreme Ultra Violet) light having a wavelength of 13 nm is considered as a candidate for the next generation exposure method.

At the same time, the manufacturing process of semiconductor devices is also diversified. For example, techniques such as chemical mechanical polishing (CMP) processes have also attracted attention as planarization techniques for solving the lack of depth of the exposure apparatus. Moreover, the structure and material of a semiconductor device are also various. For example, P-high electron mobility transistors, M-high electron mobility transistors formed by combining compounds such as GaAs and InP, and heterojunction bipolar transistors using SiGe, SiGeC and the like have been proposed.

On the other hand, with the miniaturization of circuit patterns, it is also required to accurately align the reticle on which the circuit pattern is formed and the substrate on which it is projected. The required alignment precision is one third of the circuit line width. For example, the required precision in the 90 nm design of development is 1/3, that is, 30 nm.

However, when performing substrate alignment, a wafer induced shift of the substrate due to the manufacturing process occurs, which has been a factor of lowering the performance of semiconductor devices and the yield of semiconductor device manufacturing. In this specification, this wafer induced shift is referred to as "WIS". As an example of WIS, the structure of an alignment mark becomes asymmetrical by the influence of planarization processes, such as CMP, and the shape of the resist apply | coated to the board | substrate may become asymmetrical. In addition, since the semiconductor device is manufactured through a plurality of processes, the optical conditions of the alignment mark change from process to process, and the amount of WIS fluctuates from process to process, too. In order to cope with such a problem, it is necessary to prepare a plurality of measurement conditions for alignment and determine the optimum measurement conditions for each process. In the conventional substrate alignment, the measurement conditions with the best result of the overlay inspection were determined by actually exposing the substrate under some measurement conditions and performing the overlay inspection. However, this method requires a tremendous amount of time to determine the measurement conditions. Japanese Laid-Open Patent Publication No. 4-32219 proposes a method for determining measurement conditions without performing an overlay inspection by using "a value quantifying the asymmetry and contrast of an alignment mark signal" as an index. The characteristic value related to the measurement precision calculated from the signal of the alignment mark, like "the value which quantified the asymmetry and contrast of the alignment mark signal", is called "feature value" in this specification.

In the method for determining the measurement conditions described in Japanese Patent Laid-Open No. 4-32219, the measurement conditions are determined using the average value in the substrate surface and the variation in the substrate surface as indicators. However, since measurement errors occur due to the shift / magnification / rotation of the substrate at the actual device manufacturing site, it is difficult to correspond to the WIS which is actually a problem with conventional indicators. Therefore, measurement conditions hardly affected by WIS could not be determined.

An object of the present invention is to improve measurement accuracy under measurement conditions determined without performing overlay inspection.

According to a first aspect of the present invention, an exposure apparatus for exposing each of a plurality of regions disposed on a substrate is provided.

A measuring unit configured to acquire an image signal of the alignment mark formed in the area, and measure the position of the alignment mark based on the signal;

i) measuring position of the alignment mark formed in each of at least two areas of the plurality of areas under a plurality of measurement conditions,

ii) under the plurality of measurement conditions, the characteristic value of the signal acquired for each of the at least two regions is calculated;

iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A coefficient of-is formulated based on the calculated feature value, which is formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position,

and iv) a processing unit configured to set measurement conditions for measuring the position of the alignment mark based on the coefficients calculated for each of the plurality of measurement conditions.

According to the second aspect of the present invention, an exposure apparatus for exposing each of a plurality of regions disposed on a substrate is provided.

A measuring unit configured to acquire an image signal of an alignment mark formed in the area, and measure the position of the alignment mark based on the signal;

i) measuring position of the alignment mark formed in each of at least two areas of the plurality of areas under a plurality of measurement conditions,

ii) under the plurality of measurement conditions, calculate characteristic values of the signals acquired for each of the at least two regions,

iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A processing unit configured to calculate a coefficient of-based on the calculated feature value-formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position;

And a console configured to display information of the coefficient calculated for each of the plurality of measurement conditions.

In accordance with a third aspect of the present invention, an exposure apparatus for exposing each of a plurality of regions disposed on a substrate is provided.

A measuring unit configured to acquire an image signal of an alignment mark formed in the area, and measure the position of the alignment mark based on the signal;

i) measuring position of the alignment mark formed in each of at least two areas of the plurality of areas under a plurality of measurement conditions;

ii) under the plurality of measurement conditions, the characteristic value of the signal acquired for each of the at least two regions is calculated;

iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A coefficient of-is formulated based on the calculated feature value, which is formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position,

iv) A processing section configured to set measurement conditions for measuring the position of the alignment mark on the measurement section based on the deviation of the coefficients calculated on the plurality of substrates with respect to each of the plurality of measurement conditions.

In accordance with a fourth aspect of the present invention, an exposure apparatus for exposing each of a plurality of regions disposed on a substrate is provided.

A measuring unit configured to acquire an image signal of an alignment mark formed in the area, and measure the position of the alignment mark based on the signal;

i) measuring position of the alignment mark formed in each of at least two areas of the plurality of areas under a plurality of measurement conditions,

ii) under the plurality of measurement conditions, calculate characteristic values of the signals acquired for each of the at least two regions,

iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A processing unit configured to calculate a coefficient of-based on the calculated feature value-formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position;

And a console configured to display the deviation of the coefficients calculated on the plurality of substrates for each of the plurality of measurement conditions.

According to the present invention, measurement accuracy can be improved under measurement conditions determined without performing overlay inspection, for example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]

1 is a schematic view of an exposure apparatus. The exposure apparatus 1 positions the reduced projection optical system 3 for reducing and projecting the image of the reticle 2, the substrate chuck 5 for holding the substrate 4, and positioning the substrate 4 at a predetermined position. And a substrate stage 6, an alignment detection optical system 7, and the like. A certain circuit pattern is drawn in the reticle 2. The substrate 4 is provided with a base pattern and an alignment mark in the previous step. The alignment detection optical system 7 functions as a measurement unit for measuring the position of the alignment mark 15 on the substrate 4.

11 is a flowchart showing a method of determining measurement conditions according to the present embodiment.

In step S101, the substrate 4 is loaded into the exposure apparatus 1. In step S102, the setting unit 10 in the CPU 9 sets alignment measurement conditions. The measurement condition may be, for example, measurement illumination condition, type of alignment mark, number of sample shots, or arrangement of sample shots. The sample shot is a shot region in which the alignment mark 15 is measured in order to determine the shot arrangement among the plurality of shot regions in which the alignment mark 15 is provided on the substrate 4.

In step S103, the alignment detection optical system 7 detects the position of the alignment mark 15 with respect to one sample shot of a set of sample shots on the substrate 4. 2 is a diagram showing the main components of the alignment detection optical system 7. The illumination light from the light source 71 is reflected by the beam splitter 72, passes through the lens 73, and illuminates the alignment mark 15 on the substrate 4. Light diffracted by the alignment mark 15 passes through beam splitter 72 and lens 74 and is split by beam splitter 75. The divided light beams are received by CCD sensors 76 and 77. The alignment marks 15 are enlarged by the lenses 73 and 74 to the extent that resolution can satisfy the measurement accuracy, and are imaged on the CCD sensors 76 and 77. The CCD sensors 76 and 77 respectively measure the position shift of the alignment mark 15 in the X and Y directions, and have an angular interval of 90 degrees with respect to the optical axis. Since the measurement principle in the X direction and the Y direction is the same, only the measurement of the position in the X direction will be described.

3 shows an example of alignment mark 15 used for measuring the position. In this example, a plurality of stripe alignment marks 16 having predetermined dimensions in the measurement direction (X direction) and the non-measurement direction (Y direction) are disposed at predetermined intervals between stripes continuous in the X direction. At this time, the cross section of the alignment mark 15 is recessed by the etching process, and the resist 17 is apply | coated on the alignment mark 15. FIG.

4 shows an example of the alignment mark signal 18 when the illumination light reflected by the plurality of sprite alignment marks 16 is received by the CCD sensor 76. Each alignment mark position is detected from each signal 18 shown in FIG. Finally, the average value of each alignment mark position is calculated and detected as a final alignment mark position.

In step S104, the first calculation unit 12 of the CPU 9 calculates the feature value W from the signals. The feature value W can be calculated by, for example, the following equation (1).

W = A × S ^a × C ^b × P ^c ···(One)

Where S is the asymmetry of the alignment mark signal, C is the contrast (S / N ratio), P is the shape, and A, a, b, and c are integers obtained from the relationship between the feature values W and WIS.

For the "right processing area Rw" and "left processing area Lw" of the signal shown in FIG. 5, the signal asymmetry S is defined by the following equation (2).

S = ((σ within Rw)-(σ within Lw)) / ((σ inside Rw) + (σ inside Lw)) ... (2)

Where σ is the standard deviation. Hereinafter, "right processing area Rw" and "left processing area Lw" are called "right window" and "left window", respectively.

Regarding the right window Rw and the left window Lw of the signal shown in FIG. 6,

When (contrast in w) = ((max in w)-(minimum in w)) / ((max in w) + (minimum in w)),

The signal contrast C is defined by the following equation (3).

C = ((contrast in Rw) + (contrast in Lw)) / 2 ... (3)

The shape P of the signal is defined by equation (4) for the right window Rw and the left window Lw of the signal shown in FIG.

P = {((Lw right value) + (Rw left value))-((Lw left value) + (Rw right value))} / {((Lw right value) + (Rw left value)) + ((Lw Left end value) + (Rw right end value))} ... (4)

Correlation between the feature values W and WIS has been confirmed by an experiment using a substrate on which WIS is actually generated, for example, as shown in FIG. 8. In other words, by calculating the feature value W, it is possible for the operator to know "how much the signal can generate WIS" (hereinafter referred to as "influence on the WIS"). " In the first embodiment, the feature value W is used as an index when determining measurement conditions.

Next, the first calculation unit 12 detects the position of the alignment mark with respect to each of the plurality of sample shots selected from all the shot regions on the substrate while repeating the processing operations of steps S103 to S104, and their feature values. Calculate W sequentially. After detecting the position of the alignment mark for all the sample shots and calculating the feature value W, the process proceeds to step S106.

In step S106, the global alignment which performs a statistical process of the position of the alignment mark of each sample shot, and computes the 2nd index | index which shows the position shift amount from the target arrangement | sequence of a shot sequence is performed. The second index is not based on the feature value W. The calculation of the second index is performed by the second calculating unit 13 of the CPU 9. About the method of global alignment, it is shown by Unexamined-Japanese-Patent No. 63-232321, for example.

Hereinafter, the calculation method of a global alignment is demonstrated briefly. The positional shift amount of the shot array is the shift Sx in the X direction, the shift Sy in the Y direction, the rotation angle θx about the X axis, the rotation angle θy about the Y axis, the magnification Bx in the X direction, and the Y direction. It can be described using a parameter indicating a magnification By. The detection value Ai of each sample shot is determined by equation (5) when the detection shot number is i.

···(5)

(5)

Coordinate Di of the design position of the alignment mark of each sample shot is determined by Formula (6).

···(6)

(6)

The primary coordinate change D'i determined by equation (7) is performed using six parameters (Sx, Sy, θx, θy, Bx, By) indicating the positional displacement amount of the shot array shown previously.

···(7)

(7)

Since θx and θy are minute amounts, approximations of cosθ = 1 and Sinθ = θ were used. In addition, since Bx # 1 and By # 1, approximations, such as (theta) xxBx = (theta) x, (theta) y * by = (theta) y, were used.

As shown in FIG. 9, it is considered that the alignment mark on the board | substrate is formed in the position W, and is shifted by Ai from the design position M. As shown in FIG. When the coordinate transformation D'i is performed, the positional deviation (hereinafter, referred to as "correction residual") of the alignment mark on the substrate becomes Ri. 9 is a schematic diagram showing coordinate transformation D'i and correction residual Ri. The correction residual Ri is determined by equation (8).

Ri = (Di + Ai)-D'i (8)

In the global alignment, the least square method is applied to minimize the correction residual Ri in each sample shot. That is, when the mean square sum V of the correction residual Ri is determined by equation (9),

·‥ (9)

‥ (9)

The position shift amounts (Sx, Sy, θx, θy, Bx, By) of the shift, rotation, and magnification which minimize the average square sum V, that is, the position shift amount of the shot array are calculated by the equation (10).

·‥(10)

· (10)

In the formulas (9) and (10), numerical values are substituted into the detection values (xi, yi) and the design positions (Xi, Yi) in each sample shot, and the position shift amounts (Sx, Sy) of the shift, rotation, and magnification. Θx, θy, Bx, By) are calculated. The calculation of the position shift amount of the shot array by the global alignment is completed as above.

In step S107, the second calculation unit 13 of the CPU 9 statistically calculates the feature values W of all the sample shots, and selects the first index indicating the "position shift amount from the target array of the shot array". Calculate. If wx _i and wy _i are the feature values of each sample shot, the positional displacement amount of the shot array is determined by substituting Equation (5) of the global alignment in Step S106 with Equation (11) below. Can be calculated by performing the same calculation.

···(11)

(11)

Hereinafter, the position shift amount of the calculated shot array is described as (WSx, WSy, Wθx, Wθy, WBx, WBy). By calculating the positional displacement amount of the shot array, the amount of WIS in which the mark signal can be generated can be converted into an error component such as that which is a problem in the actual device manufacturing site. This makes it possible to more accurately detect the degree of influence on the WIS.

Next, by repeating the processing operation of steps S102 to S107 while changing the measurement conditions, the first indexes are sequentially calculated under each measurement condition. Here, as measurement conditions, illumination conditions of the alignment detection optical system, types of alignment marks, the number of sample shots, the arrangement of sample shots, and the like can be used. The setting of the measurement conditions is made by the setting unit 10 of the CPU 9. The setting unit 10, the first calculating unit 12, the second calculating unit 13, and the determining unit 14 constitute a processing unit that processes the conditions for measuring the position of the alignment mark.

The control unit 11 of the CPU 9 controls the alignment detection optical system 7, the substrate stage 6, and the like so that the alignment mark is measured under a plurality of set measurement conditions.

Next, the process operation of said step S102-S107 is performed with respect to a some board | substrate, and a 1st index is calculated sequentially about each board | substrate. In step S110, the deviation of the first index between the substrates is calculated.

The positional shift component which affects the deviation of WIS under each measurement condition by the deviation of the 1st index | symbol which shows shift position shift, rotation position shift, and magnification position shift between board | substrates, and the extent of the influence on the deviation Can be predicted. In other words, the first index can be used as the final index when determining the measurement conditions.

In step S111, the measurement conditions with the smallest deviation of the first indexes between the substrates are determined as measurement conditions that are hardly affected by the WIS, and the process of determining a series of measurement conditions is completed. The determination of the optimal measurement condition is made by the determination unit 14 of the CPU 9.

By using the process of determining the measurement conditions according to the first embodiment, it is possible to easily determine the optimum measurement conditions that minimize the process error that is actually a problem at the device manufacturing site without performing overlay inspection. Become.

The shape of the alignment mark according to the third embodiment is not limited to that shown in FIG. 3. The calculation method of the mark feature value W is not specifically limited to obtaining the calculation result of said Formula (1), You may use any value as long as it is a value which has a correlation with WIS. In addition, the selected measurement condition is not specifically limited to the above-mentioned example. The deviation of the first index used in determining the measurement conditions can be determined using only the position shift component that is a problem at the actual device manufacturing site, for example, only the rotation position shift component. Moreover, you may use the value of Formula (12) and Formula (13) obtained by combining at least two of the group which consists of a shift position shift component, a rotation position shift component, and a magnification position shift component.

···(12)

(12)

···(13)

(13)

Second Embodiment

The second embodiment according to the present invention employs a step of determining measurement conditions based on the value of the first index for one substrate. The configuration and operation of the exposure apparatus other than the process of determining the measurement conditions are the same as in the first embodiment. A process of determining measurement conditions according to the second embodiment will be described with reference to the flowchart of FIG. 12. The processing contents of steps S201 to S208 from the substrate loading until the first index is calculated are the same as the processing contents of steps S101 to S108.

In the second embodiment, the first index is calculated for one substrate in step S209.

In step S210, the measurement conditions with the smallest first index are determined as measurement conditions that are less likely to be affected by WIS, and the process of determining a series of measurement conditions is terminated.

By using the process of determining the measurement conditions according to the second embodiment, the number of substrates to be measured can be reduced to one sheet in order to determine the measurement conditions, and the time for determining the measurement conditions can be shortened.

The 1st index used when determining a measurement condition can be provided using only the error component which is a problem in an actual device manufacturing site, for example, only a rotation position shift component. Moreover, it is also possible to use the value of Formula (14) and Formula (15) obtained by combining at least two of the group which consists of a shift position shift component, a rotation position shift component, and a magnification position shift component.

‥·(14)

‥ · (14)

···(15)

(15)

[Third Embodiment]

In the third embodiment, the first index for each of the plurality of sample shot batches is calculated, and the measurement conditions are determined based on the average value. The configuration and operation of the exposure apparatus other than the process of determining the measurement conditions are the same as in the first embodiment. The process of determining the measurement conditions according to the third embodiment will be described using the flowchart of FIG.

The processing contents of steps S301 to S304 until the feature value W is calculated from the substrate loading are the same as the processing contents of steps S101 to S104. In the third embodiment, the processing operations of steps S301 to S304 are repeated for all possible sample shot positions for the plurality of sample shot arrangements.

In step S306, one sample shot arrangement 1 is selected from the plurality of sample shot arrangements as shown in FIG. Based on the global alignment in step S307 and the feature value calculated in step S308, the positional shift amount from the target array of the shot array is calculated. The processing contents of steps S307 to S308 are the same as the processing contents of steps S106 to S107. The processing operations of steps S307 to S308 are repeated until the calculation for the n sample shot batches is completed. In step S310, the average value of the position shift amount from the target array of shot arrays is calculated based on the feature values of the n sample shot arrays. The processing operation of steps S301 to S310 is repeated while changing the measurement conditions and the substrate. In step S313, the deviation of the average value of the position shift amounts from the target array of shot arrays between the substrates is calculated. The operation of determining the measurement condition from the index calculated in step S314 is the same as that of S111. According to the third embodiment, it is possible to improve the reproducibility of the positional shift amount of the shot array and the precision when determining the measurement conditions. In addition, as in the second embodiment, the measurement conditions may be determined based on the position shift amount rather than the deviation in the position shift amount of the shot array.

Fourth Embodiment

The fourth embodiment increases the precision when determining the measurement conditions in the process where the correction residual component is a problem by the WIS. The configuration and operation of the exposure apparatus other than the process of determining the measurement conditions are the same as in the first embodiment. Only the process of determining the measurement conditions according to the fourth embodiment will be described using the flowchart of FIG.

The processing contents of steps S401 to S406 from the substrate loading to the global alignment are the same as the processing contents of steps S101 to S106. In the fourth embodiment, a residual position shift component other than the shift position shift component, the magnification position shift component, and the rotation position shift component of the shot array is calculated in step S407, and its 3? Is obtained, where? Is the residual. Standard deviation of the misalignment component. The residual position shift component of the shot array is Ri obtained when the equation (5) is replaced with the equation (11) and the equations (6) to (10) are calculated. In step S409, the measurement condition is determined using the residual position shift component 3σ of the shot array as the first index, and the process of determining the series of measurement conditions is completed. Thereby, even if the error of the residual position shift component by WIS becomes a problem, measurement conditions can be determined. In addition, as in the third embodiment, an average value of a plurality of sample shot arrangements may be used.

[Fifth Embodiment]

In the fifth embodiment, the measurement conditions having a low contrast (S / N ratio) C of the mark signal defined by the equation (3) are first removed from the candidate, thereby reducing the time for determining the measurement conditions and improving the accuracy of the decision. To realize. The configuration and operation of the exposure apparatus other than the process of determining the measurement conditions are the same as in the first embodiment. The process of determining the measurement conditions according to the fifth embodiment will be described using the flowchart of FIG. 15. The processing contents of steps S501 to S503 from the substrate loading until the position of the alignment mark is detected are the same as the processing contents of steps S101 to S103. In the fifth embodiment, when it is determined in step S504 that the signal contrast (S / N ratio) is smaller than the set threshold value, the measurement condition at that time is removed from the determination candidate. The reason is that when the contrast of the mark signal falls below a certain threshold, the S / N ratio of the signal decreases drastically. As a result, a significant decrease in alignment accuracy due to noise occurs. In addition, since the correlation between the feature value W and the WIS shown in FIG. 8 is weakened, there is a possibility that the index cannot be accurately calculated under measurement conditions in which the contrast is equal to or less than a certain threshold. In steps S505 to S512, subsequent processing operations for the measurement conditions remaining as candidates are the same as the processing operations of steps S104 to S111. According to the fifth embodiment, when there is a measurement condition whose contrast is equal to or less than the set threshold value, the time for determining the measurement condition and the accuracy of the decision can be improved. The processing operation of step S504 according to the fifth embodiment may be applied to the second to fourth embodiments.

[Sixth Embodiment]

The sixth embodiment according to the present invention employs a step of increasing the reliability at the time of determining the measurement conditions by determining the final measurement conditions using a plurality of different indices. The configuration and operation of the exposure apparatus other than the process of determining the measurement conditions are the same as in the first embodiment. The process of determining the measurement conditions according to the sixth embodiment will be described using the flowchart shown in FIG. 16. The processing contents of steps S601 to S610 (from the substrate loading to the calculation of the deviation between the substrates of the positional shift amount from the target arrangement of the shot array based on the feature value) are the same as the processing contents of the steps S101 to S110. same. In the sixth embodiment, in step S611, the deviation between the substrates of the magnification position shift component of the shot array not based on the feature value calculated in step S606 is used as one index for determining the measurement conditions. do. In step S612, the standard deviation Ri (3σ) of the correction residual Ri defined by the formula (8) calculated in step S606 is calculated, and the average value Ri (3σ) _{( ave )} is obtained. The calculated average value Ri (3σ) _{( ave )} is used as one index for determining measurement conditions. In step S613, the final measurement conditions are determined using the weighted average value of each index calculated in steps S610 to S612, and the process of determining the series of measurement conditions is completed. According to the sixth embodiment, it is possible to increase the reliability of determining the measurement conditions rather than the case of determining the measurement conditions based only on one type of indicator. The type and combination of the indicators are not particularly limited to those used in steps S610 to S612, and the positional shift amount of the shot array as in the second embodiment can also be used. In addition, the deviation in the board | substrate of the position shift of the shot array which is not based on the feature value used at step S611 is not limited to the magnification position shift component. In addition, the method of determining final measurement conditions in step S613 is not limited to the weighted average of each index | index.

[Modification example]

In the above embodiment, based on the first index which is a coefficient of the formula (7) of the coordinate transformation calculated by substituting the formula (5) by the formula (11), or the standard of the first index of the plurality of substrates The CPU 9 automatically sets the measurement conditions based on the deviation such as the deviation. However, the CPU 9 can display the deviation of the first index calculated under the plurality of measurement conditions or the first index of the plurality of substrates on the display unit, and based on the displayed information, the exposure apparatus ( The user of 1) can set preferable measurement conditions. Here, the display unit may be included in, for example, a console connected to the CPU 9 of the exposure apparatus 1.

[Device manufacturing]

Next, an embodiment of a device manufacturing method using the above exposure apparatus will be described with reference to FIGS. 17 and 18. 17 is a flowchart for explaining the manufacture of devices (semiconductor chips such as IC and LSI, LCDs, CCDs, etc.). Here, the manufacturing method of a semiconductor chip is demonstrated as an example.

In step S1 (circuit design), the circuit of the semiconductor device is designed. In step S2 (mask preparation), a mask (also called a master or a reticle) is produced based on the designed circuit pattern. In step S3 (wafer manufacture), a wafer (also called a substrate) is manufactured using a material such as silicon. Step S4 (wafer process) is called a pre-process, and uses a mask and a substrate to form an actual circuit on the substrate by the lithographic technique by the above exposure apparatus. Step S5 (assembly) is called a post-process and is a process of forming a semiconductor chip using the substrate produced in step S4. This process includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step S6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device produced in step S5 are performed. After this step, the semiconductor device is completed and shipped (step S7).

18 is a detailed flowchart of the wafer process of step S4. In step S11 (oxidation), the surface of the substrate is oxidized. In step S12 (CVD), an insulating film is formed on the surface of the substrate. In step S13 (electrode formation), an electrode is formed on the substrate by vapor deposition. In step S14 (ion implantation), ions are implanted into the substrate. In step S15 (resist process), a photosensitive agent is applied to the substrate. In step S16 (exposure), the substrate is exposed through the circuit pattern of the mask using the exposure apparatus described above. In step S17 (development), the exposed substrate is developed. In step S18 (etching), portions other than the developed resist image are etched. In step S19 (resist stripping), the resist which is not finished after etching is removed. By repeating these steps, a circuit pattern is formed multiplely on a board | substrate.

Although the present invention has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions.

1 is a schematic view of an exposure apparatus.

FIG. 2 is a diagram showing the alignment detection optical system 7 in FIG. 1.

3 is a diagram illustrating an example of an alignment mark.

4 is a diagram illustrating an example of an alignment mark signal.

5 is an explanatory diagram showing a feature value.

6 is an explanatory diagram showing another feature value.

7 is an explanatory diagram showing still another feature value.

8 is a diagram illustrating a correlation between feature values and WIS.

9 is an explanatory diagram showing a relationship between the coordinate change D'i and the correction residual Ri.

10 is a diagram illustrating an example of arranging a plurality of sample shots.

11 is a flowchart showing determination of measurement conditions according to the first embodiment.

12 is a flowchart showing determination of measurement conditions according to the second embodiment.

13 is a flowchart showing determination of measurement conditions according to the third embodiment.

14 is a flowchart showing determination of measurement conditions according to the fourth embodiment.

15 is a flowchart showing determination of measurement conditions according to the fifth embodiment.

16 is a flowchart showing determination of measurement conditions according to the sixth embodiment.

17 is a flowchart for explaining the manufacture of a device using the exposure apparatus.

FIG. 18 is a flowchart showing details of the wafer process of step S4 of the flowchart shown in FIG. 17.

Claims (13)

An exposure apparatus for exposing each of a plurality of regions disposed on a substrate, A measuring unit configured to acquire an image signal of an alignment mark formed in the area, and measure the position of the alignment mark based on the signal; i) measuring position of the said alignment mark formed in each of at least 2 area | regions of the said some area | region under a some measurement condition, ii) under the plurality of measurement conditions, the characteristic value of the signal acquired for each of the at least two regions is calculated; iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A coefficient of-is formulated based on the calculated feature value, which is formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position, and iv) a processing unit configured to set measurement conditions for measuring the position of the alignment mark on the measurement unit based on the coefficients calculated for each of the plurality of measurement conditions. An exposure apparatus for exposing each of a plurality of regions disposed on a substrate, A measuring unit configured to acquire an image signal of an alignment mark formed in the area, and measure the position of the alignment mark based on the signal; i) measuring position of the alignment mark formed in each of at least two areas of the plurality of areas under a plurality of measurement conditions, ii) under the plurality of measurement conditions, the characteristic value of the signal acquired for each of the at least two regions is calculated; iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A processing unit configured to calculate a coefficient of-based on the calculated feature value-formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position; And a console configured to display information of the coefficient calculated for each of the plurality of measurement conditions. An exposure apparatus for exposing each of a plurality of regions disposed on a substrate, A measuring unit configured to acquire an image signal of an alignment mark formed in the area, and measure the position of the alignment mark based on the signal; i) measuring position of the alignment mark formed in each of at least two areas of the plurality of areas under a plurality of measurement conditions; ii) under the plurality of measurement conditions, the characteristic value of the signal acquired for each of the at least two regions is calculated; iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A coefficient of-is formulated based on the calculated feature value, which is formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position, iv) a processing unit configured to set measurement conditions for measuring the position of the alignment mark on the measurement unit based on the deviation of the coefficients calculated on the plurality of substrates with respect to each of the plurality of measurement conditions. Exposure apparatus. An exposure apparatus for exposing each of a plurality of regions disposed on a substrate, A measuring unit configured to acquire an image signal of an alignment mark formed in the area, and measure the position of the alignment mark based on the signal; i) measuring position of the said alignment mark formed in each of at least 2 area | regions of the said some area | region under a some measurement condition, ii) under the plurality of measurement conditions, the characteristic value of the signal acquired for each of the at least two regions is calculated; iii) a conversion equation for transforming the design position of the alignment mark into an approximation of the feature value corresponding to the design position with respect to each of the plurality of measurement conditions, by replacing the measured position with the feature value; A processing unit configured to calculate a coefficient of-based on the calculated feature value-formulated from a coordinate transformation formula for converting a coordinate of a design position into a value approximating the coordinate of the measured position corresponding to the design position; And a console configured to display the deviation of the coefficients calculated on the plurality of substrates with respect to each of the plurality of measurement conditions. The method of claim 1, And the feature value includes at least one of a group element consisting of a value representing the asymmetry of the signal, a value representing the contrast of the signal, and a value representing the shape of the signal. The method of claim 1, And the processing unit is configured to set measurement conditions for minimizing the coefficients among the plurality of measurement conditions. The method of claim 3, wherein And the processing unit is configured to set measurement conditions for minimizing the deviation of the coefficients among the plurality of measurement conditions. Exposing the substrate to radiant energy using the exposure apparatus of claim 1; Developing the exposed substrate; Processing the developed substrate to produce a device. Exposing the substrate to radiant energy using the exposure apparatus of claim 2, Developing the exposed substrate; Processing the developed substrate to produce a device. Exposing the substrate to radiant energy using the exposure apparatus of claim 3; Developing the exposed substrate; Processing the developed substrate to produce a device. Exposing the substrate to radiant energy using the exposure apparatus of claim 4; Developing the exposed substrate; Processing the developed substrate to produce a device. The method according to any one of claims 1 to 4, And the processing unit calculates the coefficient by statistically processing the calculated feature value. The method according to any one of claims 1 to 4, And the processing unit calculates the coefficient by applying a least squares method to minimize a correction residual between the calculated feature value and an approximation of the feature value.

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