JP2008205312A - Exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure method at lost cost which is capable of accurately detecting the orthogonality of a stage-moving shaft of an exposure apparatus during exposure processing. <P>SOLUTION: In a semiconductor wafer WF, respective cells CLa, CLc are formed adjacent in the X-axis direction of the stage-moving shaft, a plot pattern forming region 15 and an inspection pattern 16 are formed in the cell CLa, and a plotting pattern forming area 15 and an inspection pattern 17 are formed in the cell CLc. Respective inspection patterns 16, 17 are formed in a scribe region SL formed between respective cells CLa, CLc, the inspection pattern 16 constitutes the main scale of a caliper and the inspecting pattern 17 constitutes the vernier scale of the caliper. Thus, the linear rod-like patterns of respective inspecting patterns 16, 17 are used as scales on the basis of the principle of vernier, positional deviations of respective inspecting patterns 16, 17 can be measured visually, and deviations in the arrays of respective cells CLa, CLc can be detected on the basis of the positional deviations. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exposure method, and more particularly to an exposure method in which the entire surface of a substrate is scanned while repeating shot exposure to transfer a drawing pattern on a photomask onto the substrate.

In the manufacture of a semiconductor device, a photolithography technique for transferring a drawing pattern formed on a photomask onto a semiconductor wafer (semiconductor substrate) is used.
An exposure apparatus (stepper) used in the photolithographic technique has a substrate stage on which a semiconductor wafer coated with a photoresist (photosensitive resin) is placed and moved two-dimensionally, and a photomask is placed on the substrate. A dimensionally moving mask stage, an illumination optical system unit that illuminates the photomask with exposure light, and a projection optical system unit that projects an image of a drawing pattern of the photomask illuminated with the exposure light onto the surface of the semiconductor wafer (For example, refer to Patent Document 1).
JP 2003-347184 A (pages 2 to 18, FIGS. 1 to 24)

In order to create a plurality of identical semiconductor devices from one semiconductor wafer, first, rectangular cells constituting the semiconductor device are arranged in a grid pattern in the vertical and horizontal directions on the plane of the semiconductor wafer, and then formed. A semiconductor chip formed from each cell is obtained by dividing the semiconductor wafer into cells using a scribing method or a dicing method.
In other words, the semiconductor wafer is divided into grids by scribe areas (dicing areas) arranged in a grid pattern in the vertical and horizontal directions orthogonal to each other, and each rectangular grid of the semiconductor wafer becomes a cell and is divided from the semiconductor wafer. Each cell thus formed becomes a semiconductor chip, and each semiconductor chip becomes a semiconductor device.

Here, in order to arrange and form the cells in a grid pattern on the semiconductor wafer, a semiconductor wafer having a photoresist coated on the surface is prepared, and the semiconductor wafer is placed and fixed on the substrate stage of the exposure apparatus. To do.
Also, one photomask on which a drawing pattern is formed is prepared, and the photomask is attached and fixed to the mask stage of the exposure apparatus.
Then, using the exposure apparatus, the entire surface of the semiconductor wafer is scanned while repeating the operation of projecting the drawing pattern of the photomask onto the semiconductor wafer and transferring it to one cell by shot exposure.

That is, after a photomask drawing pattern is projected onto a semiconductor wafer, shot exposed and transferred to one cell, the substrate stage or mask stage is moved to one cell in the first direction (X-axis direction) on the semiconductor wafer. The same photomask is transferred to each column of cells arranged in the first direction by repeating the operation of moving by the same amount and transferring the drawing pattern of the same photomask to the cell adjacent to the cell. Transfer the drawing pattern.
Subsequently, the substrate stage or the mask stage is moved by one cell in the second direction (Y-axis direction) orthogonal to the first direction on the semiconductor wafer, and arranged in the first direction as described above. The operation of transferring the same photomask drawing pattern to each cell of one row is repeated.

Note that the photomask drawing pattern transfer process is repeated several times to create a circuit component of the semiconductor device, and the photomask is replaced each time the transfer process is performed.
At present, the mainstream photomask is an enlarged mask drawn 4 to 5 times larger than the drawing pattern, and this enlarged mask is called a reticle.

  By the way, if there is a deviation in the orthogonality of the movement axis of the mask stage or the substrate stage (hereinafter referred to as “stage movement axis”) due to troubles in parts of the exposure apparatus, the arrangement of the cells formed on the semiconductor wafer. Also, a deviation occurs, and the arrangement accuracy of each cell is lowered.

FIG. 13 shows that when the orthogonality of the stage movement axis is shifted (θx ° with respect to the X axis and θy ° with respect to the Y axis), the alignment of the cells CL formed on the semiconductor wafer WF is also shifted. It is a schematic diagram which shows that occurs.
On the semiconductor wafer WF mounted and fixed on the substrate stage PST, a plurality of rectangular cells CL are arranged in the vertical and horizontal directions. A scribe region (dicing region) SL is provided between the cells CL.

As shown in FIG. 13, when the alignment accuracy of the cells CL is lowered, the scribe areas (scribe lines) SL arranged in a lattice shape in the vertical and horizontal directions on the semiconductor wafer WF are not aligned, and the scribe areas SL are not aligned. They are no longer orthogonal to each other.
For this reason, when the semiconductor wafer WF is divided into the cells CL using the scribing method (dicing method), the cells CL cannot be accurately divided from the semiconductor wafer WF.

Therefore, in the conventional exposure method, an inspection wafer on which a dedicated pattern for inspecting the orthogonality of the stage moving axis is formed, and a dedicated measuring machine for detecting the pattern of the inspection wafer are prepared. .
Then, the inspection wafer is mounted and fixed on the substrate stage of the exposure apparatus, the pattern of the inspection wafer is detected using a measuring machine, and the orthogonality of the stage moving axis is inspected based on the detection result, and the inspection is performed. Based on the results, the exposure apparatus was maintained and inspected to manage the equipment.

However, since such a conventional inspection method cannot be performed online during the exposure process of a semiconductor wafer as a product, it has been necessary to periodically detect the intervals between the manufacturing of the semiconductor wafers and periodically perform it offline.
For this reason, when troubles such as parts of the exposure apparatus occur suddenly and a deviation occurs in the orthogonality of the stage movement axis during the exposure processing of the semiconductor wafer that is the product, the deviation is grasped during the product processing. Therefore, there is a problem that a defective semiconductor wafer in which the alignment accuracy of each cell is lowered is manufactured as a finished product.

  In addition, in the conventional inspection method, it is necessary to prepare an inspection wafer and a dedicated measuring machine as inspection equipment, and then to find out the interval between the production of semiconductor wafers and perform periodic inspections offline. There is also a problem that the manufacturing cost of the semiconductor wafer is increased by the labor required for the inspection equipment and the periodic inspection.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an exposure method capable of accurately detecting the orthogonality of the stage moving axis of the exposure apparatus during the exposure process at low cost. There is to do.

  Reference numerals and the like in parentheses described in [Means for Solving the Problems] and [Effects of the Invention] correspond to reference numerals and the like of constituent members and constituent elements described in [Best Mode for Carrying Out the Invention]. It is a thing.

The invention described in claim 1
In the exposure method of scanning the entire surface of the substrate while repeating shot exposure and transferring the photomask drawing pattern onto the substrate,
In the first cell (CLa) transferred and formed on the substrate (WF) from the first photomask (11a, 21a, 31a, 41a), in addition to the drawing pattern formation region (15) where the drawing pattern is formed, A first inspection pattern (16) is provided;
The second cell (CLb, CLc) and the third cell (CLd, CLe) transferred from the second photomask (11b, 21b, 31b, 41b) onto the substrate are identical to the first cell (CLa). In addition to the drawing pattern formation region (15) where the drawing pattern is formed, a second inspection pattern (17) is provided,
The center of the first cell (CLa) coincides with the center point (0) of the XY axis where the X axis and the Y axis of the stage movement axis of the exposure apparatus are orthogonal,
The second cells (CLb, CLc) are arranged in the X-axis direction with respect to the first cell (CLa),
The third cell (CLd, CLe) is arranged in the Y-axis direction with respect to the first cell (CLa),
Based on the vernier principle in which the first inspection pattern (16) is the main scale and the second inspection pattern (17) is the subscale, the first inspection pattern (16) and the second inspection pattern of the first cell (CLa) Detecting the displacement of the arrangement of the first cell (CLa) and the second cell (CLb, CLc) with respect to the X axis from the displacement of the second inspection pattern (17) of the cells (CLb, CLc);
Based on the Vernier principle, the first test pattern (16) of the first cell (CLa) and the second test pattern (17) of the third cell (CLd, CLe) are displaced from each other with respect to the Y axis. Detecting a shift in the arrangement of one cell (CLa) and the third cell (CLd, CLe)
A technical feature is to detect the orthogonality of the stage movement axis based on the displacement of the arrangement of the first cell (CLa), the second cell (CLb, CLc), and the third cell (CLd, CLe).

Invention of Claim 2 is set in the exposure method of Claim 1,
The second cell (CLb, CLc) includes a cell (CLb) disposed on the negative side in the X-axis direction with respect to the first cell (CLa) and an X-axis direction with respect to the first cell (CLa). Cell (CLc) arranged on the plus side (CLc) of
The third cell (CLd, CLe) includes a cell (CLd) disposed on the negative side in the Y-axis direction with respect to the first cell (CLa) and a Y-axis direction with respect to the first cell (CLa). And a cell (CLc) arranged on the plus side (CLe) of the substrate.

The invention described in claim 3 is the exposure method according to claim 1 or 2,
The first inspection pattern (16) and the second inspection pattern (17) are disposed in a scribe region (SL) provided between the cells (CLa to CLe). To do.

Invention of Claim 4 is set in the exposure method of Claim 3,
The drawing pattern formation region (15) of each of the cells (CLa to CLe) has a rectangular shape,
The first inspection pattern (16) and the second inspection pattern (17) are technically characterized in that they are arranged at both ends of each side of the drawing pattern formation region (15).

Invention of Claim 5 is set in the exposure method of Claim 3,
The drawing pattern formation region (15) of each of the cells (CLa to CLe) has a rectangular shape,
The first inspection pattern (16) and the second inspection pattern (17) are technically characterized in that they are arranged at an appropriate location on each side of the drawing pattern formation region (15).

The invention described in claim 6 is the exposure method according to claim 1 or 2, wherein
The first inspection pattern (16) and the second inspection pattern (17) are technically characterized in that they are arranged in the drawing pattern formation region (15) of each of the cells (CLa to CLe). .

<Claim 1>
In claim 1, the first inspection pattern (16) of the first cell (CLa) is based on Vernier's principle in which the first inspection pattern (16) is the main scale and the second inspection pattern (17) is the sub scale. 16) and a displacement of the arrangement of the first cell (CLa) and the second cell (CLb, CLc) with respect to the X axis are detected from the positional deviation of the second inspection pattern (17) of the second cell (CLb, CLc). .
Further, based on the Vernier principle, the Y axis is determined from the positional deviation between the first inspection pattern (16) of the first cell (CLa) and the second inspection pattern (17) of the third cell (CLd, CLe). The displacement of the arrangement of the first cell (CLa) and the third cell (CLd, CLe) is detected.
As a result, the deviation of the arrangement of the first cell (CLa) and the second cell (CLb, CLc) with respect to the X axis, and the deviation of the arrangement of the first cell (CLa) and the third cell (CLd, CLe) with respect to the Y axis. Based on the above, the orthogonality of the stage moving axis can be detected.

When it is detected that the orthogonality of the stage movement axis is shifted, the exposure processing of the substrate (WF) is stopped in a state where the transfer of the first to third cells (CLa to CLe) is completed. Then, the substrate is discarded as a defective product, and inspected and maintained in order to investigate troubles of parts of the exposure apparatus, and after the deviation of the orthogonality of the stage moving axis is eliminated, the exposure processing of a new substrate is resumed.
When it is detected that the orthogonality of the stage movement axis is not shifted, the second photomask (11b, 21b, 31b, 41b), the exposure processing of the substrate (WF) is continued as usual.

  Thus, since the inspection method according to the first aspect can be executed online during the exposure process of the substrate as the product, troubles such as parts of the exposure apparatus suddenly occur, and the stage during the exposure process of the substrate as the product occurs. Even if there is a deviation in the orthogonality of the movement axis, it is possible to grasp the deviation during the product processing. It is never manufactured.

In addition, according to the first aspect of the present invention, it is not necessary to periodically inspect the inspection substrate (inspection wafer) and the dedicated measuring machine as in the conventional inspection method. Compared to the conventional inspection method, the manufacturing cost of the substrate can be reduced by the labor required for the equipment and the periodic inspection.
Therefore, according to the first aspect, an exposure method capable of accurately detecting the orthogonality of the stage moving axis of the exposure apparatus during the exposure process can be provided at low cost.

<Claim 2>
Only one cell on the plus or minus side in the X-axis direction with respect to the first cell (CLa) is provided as the second cell (CLb, CLc), and the misalignment between the cell and the first cell (CLa) is detected. Even in this case, it is possible to detect the deviation of the arrangement of the first cell and the second cell with respect to the X axis of the stage movement axis, but there is a possibility that an error may occur in the detection value of the deviation of the arrangement depending on the transfer accuracy of each cell. is there.
Therefore, as described in claim 2, with respect to the first cell (CLa) arranged at the center of the XY axis, the deviation value of the arrangement of the second cell (CLc) arranged on the plus side in the X axis direction, If the deviation value of the arrangement of the second cells (CLb) arranged on the minus side in the X-axis direction is obtained and the average value of the deviation values is taken, it depends on the transfer accuracy of each cell (CLa to CLc). Since it becomes possible to correct the error, it is possible to accurately obtain the displacement of the arrangement of the first cell and the second cell with respect to the X axis of the stage moving axis.

Similarly, only one cell on the positive side or the negative side in the Y-axis direction with respect to the first cell (CLa) is provided as the third cell (CLd, CLe), and the arrangement of the cell and the first cell (CLa) Even when a shift is detected, it is possible to detect the shift of the arrangement of the first cell and the third cell with respect to the Y axis of the stage movement axis. However, depending on the transfer accuracy of each cell, there is an error in the detection value of the shift of the array. May occur.
Therefore, as described in claim 2, with respect to the first cell (CLa) arranged at the center of the XY axis, the deviation value of the arrangement of the third cell (CLe) arranged on the Y axis direction plus side; If the deviation value of the arrangement of the second cells (CLd) arranged on the minus side in the X-axis direction is obtained and the average value of the deviation values is taken, the transfer of each cell (CLa, CLd, CLe) Since an error due to accuracy can be corrected, the displacement of the arrangement of the first cell and the third cell with respect to the Y axis of the stage moving axis can be accurately obtained.

<Claim 3: Corresponds to the first to third embodiments>
According to a third aspect of the present invention, the first inspection pattern (16) and the second inspection pattern (17) are arranged in a scribe region (SL) provided between the cells (CLa to CLe). Therefore, the drawing pattern formed in the drawing pattern formation region (15) of each cell (CLa to CLe) is not restricted by each inspection pattern (16, 17).

<Claim 4: Corresponds to the first embodiment>
According to a fourth aspect, the drawing pattern formation region (15) of each cell (CLa to CLe) has a rectangular shape, and the first inspection pattern (16) and the second inspection pattern (17) are formed in the drawing pattern formation region ( 15) at both ends of each side.

Here, although the displacement values of the cell arrays detected for both end portions (α, γ) of each side of the drawing pattern formation region (15) should be equal, each of the inspection patterns (16, 17) has the same value. Depending on the transfer accuracy, an error may occur in the deviation value.
Therefore, if an average value of the deviation of the arrangement of the cells detected for both end portions of each side of the drawing pattern formation region (15) is taken, an error due to the transfer accuracy of each inspection pattern can be corrected. Since this becomes possible, the deviation of the arrangement of each cell can be accurately obtained.

<Claim 5: Corresponds to the second embodiment>
According to the fifth aspect, the drawing pattern formation region (15) of each cell (CLa to CLe) has a rectangular shape, and the first inspection pattern (16) and the second inspection pattern (17) are formed in the drawing pattern formation region ( 15) is arranged at one appropriate position on each side.
Therefore, according to the fifth aspect, since the area of the portion where the respective inspection patterns (16, 17) are not provided in the scribe region (SL) is larger than that of the fourth aspect, various test areas are provided in the portion. There is an advantage that a pattern can be formed and used effectively.

<Claim 6: Corresponds to the fourth embodiment>
According to a sixth aspect of the present invention, the first inspection pattern (16) and the second inspection pattern (17) are arranged in the drawing pattern formation region (15) of each cell (CLa to CLe).
Therefore, in claim 6, in contrast to claim 3 in which each inspection pattern (16, 17) is formed in the scribe area (SL), it can be effectively used by forming various test patterns in the scribe area. There are advantages.

By the way, in the sixth aspect, since each inspection pattern is formed in the drawing pattern forming region and each inspection pattern (16, 17) is separated, each inspection pattern is adjacent. In addition, the positional deviation of each inspection pattern cannot be directly measured visually using a metal microscope.
Accordingly, in claim 6, a scale line (D) is provided in the finder of the metal microscope, and one end of the scale line is made to coincide with the first inspection pattern (16) so as to extend the first inspection pattern. By visually measuring the positional deviation between the other end of the scale line and the second inspection pattern (17), the positional deviation of each inspection pattern (16, 17) is visually measured indirectly via the scale line. do it.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In each embodiment, the same components and components as those in the prior art shown in FIG. Further, in each embodiment, the same constituent members and constituent elements are denoted by the same reference numerals, and duplicate descriptions are omitted for portions having the same contents.

<First Embodiment>
FIG. 1 is a plan view showing the main configuration of photomasks 11a and 11b used in the first embodiment.
In the first embodiment, two photomasks 11a and 11b are used.
On each of the photomasks 11a and 11b, there is provided a rectangular drawing pattern forming region 12 in which the same drawing pattern (not shown) for forming a circuit component of a semiconductor device is formed.

In the photomask 11a, a total of eight identical inspection patterns 13 are formed near the four corners outside the four sides of the drawing pattern formation region 12. That is, the same inspection pattern 13 is formed on the outer sides of both end portions of each side of the drawing pattern forming region 12.
The inspection pattern 13 for inspecting the orthogonality of the stage moving axis is configured by arranging seven straight bar-like patterns having the same thickness at a constant interval (pitch) Ta.

In the photomask 11b, a total of eight identical inspection patterns 14 are formed near the four corners outside the four sides of the drawing pattern formation region 12. That is, the same inspection pattern 14 is formed on the outer sides of both end portions of each side of the drawing pattern forming region 12.
The inspection pattern 14 for inspecting the orthogonality of the stage moving axis is configured by arranging eight linear bar-like patterns having the same thickness with a constant interval Tb.

That is, the difference between the photomasks 11 a and 11 b is only the inspection patterns 13 and 14 provided at the peripheral edge of the drawing pattern formation region 12.
The difference between the inspection patterns 13 and 14 is only the spacing Ta and Tb between the straight bar-like patterns.
Note that the straight bar-like patterns constituting each of the inspection patterns 13 and 14 are arranged perpendicular to the respective sides of the drawing pattern forming region 12.
By the way, each of the photomasks 11a and 11b may be an enlarged mask (reticle) drawn to a size 4 to 5 times larger than the drawing pattern, or may be an equal size mask drawn to the same size as the drawing pattern.

FIG. 2 is a plan view showing the main configuration of the semiconductor wafer (substrate) WF on which the cells CLa to CLe are formed in the first embodiment.
In the exposure method according to the first embodiment, first, a semiconductor wafer WF having a surface coated with a photoresist is prepared, and the semiconductor wafer WF is placed and fixed on a substrate stage (not shown) of an exposure apparatus (not shown). To do.
Further, the photomask 11a is attached and fixed to a mask stage (not shown) of the exposure apparatus.

  Then, by using the exposure apparatus, the drawing pattern and each inspection pattern 13 formed in the drawing pattern forming region 12 of the photomask 11a are projected onto the semiconductor wafer WF and shot exposure is performed, whereby the drawing pattern and each inspection are inspected. The working pattern 13 is transferred to one cell CLa.

As a result, a drawing pattern formation region 15 to which the drawing pattern formation region 12 is transferred is formed in the cell CLa on the semiconductor wafer WF, and each inspection pattern 16 to which each inspection pattern 13 is transferred is formed. At this time, alignment is performed so that the center point (origin) 0 of the XY axis where the X axis and the Y axis of the stage moving axis are orthogonal to the center of the cell CLa.

Next, the photomask 11a is removed from the mask stage of the exposure apparatus, and the photomask 11b is attached and fixed to the mask stage.
Then, by using the exposure apparatus, the drawing pattern and each inspection pattern 14 formed in the drawing pattern forming region 12 of the photomask 11b are projected onto the semiconductor wafer WF and shot exposure is performed, whereby the drawing pattern and each inspection are inspected. The working pattern 14 is transferred to the four cells CLb to CLe.

As a result, in the cells CLb to CLe on the semiconductor wafer WF, a drawing pattern forming region 15 to which the drawing pattern forming region 12 is transferred is formed, and each inspection pattern 17 to which each inspection pattern 14 is transferred is formed. Formed Here, the test patterns 16 and 17 are formed in the scribe region SL provided between the cells CLb to CLe.

  At this time, the cell CLb is disposed adjacent to the minus side in the X-axis direction with respect to the cell CLa, and the cell CLc is adjacent to the plus side (opposite side of the cell CLb) in the X-axis direction (first direction). The cell CLd is disposed adjacent to the negative side in the Y-axis direction (second direction), and the cell CLe is disposed adjacent to the positive side in the Y-axis direction (opposite the cell CLc). As shown, the cells CLa to CLe are aligned.

That is, from the state transferred from the photomask 11a to the cell CLa, the substrate stage or the mask stage is moved to the minus side in the X-axis direction by one cell, and the drawing pattern of the photomask 11b and each inspection pattern 14 are moved. Transferring to the cell CLb on the left side of the cell CLa in the figure.
Next, from the state transferred from the photomask 11a to the cell CLa, the substrate stage or the mask stage is moved by one cell to the plus side in the X-axis direction, and the drawing pattern of the photomask 11b and each inspection pattern 14 are moved. Then, transfer to the cell CLc on the right side of the cell CLa in the figure.

Subsequently, from the state transferred from the photomask 11a to the cell CLa, the substrate stage or mask stage is moved to the minus side of the Y-axis direction by one cell, and the drawing pattern of the photomask 11b and each inspection pattern 14 are moved. Then, transfer to the cell CLd adjacent to the bottom of the cell CLa.
Next, from the state transferred from the photomask 11a to the cell CLa, the substrate stage or the mask stage is moved to the plus side in the Y-axis direction by one cell, and the drawing pattern of the photomask 11b and each inspection pattern 14 are moved. Then, transfer to the cell CLe adjacent to the cell CLa in the figure.

  3A and 4A are plan views showing the vicinity of adjacent portions of the test patterns 16 and 17 on the positive side in the Y-axis direction of the cells CLa and CLc in the first embodiment. It is an enlarged view of the part α shown in FIG.

The inspection pattern 16 for inspecting the orthogonality of the stage moving axis is obtained by transferring the inspection pattern 13 of the photomask 11a. Therefore, the test pattern 16 is configured by arranging seven straight bar-shaped patterns having the same thickness at a constant interval Pa. Of the straight bar-like patterns constituting the inspection pattern 16, only the length of one central pattern 16a is set larger than the other patterns.
Here, the interval Pa between the inspection patterns 16 corresponds to the interval Ta between the inspection patterns 13. For example, when the photomask 11a is a 4 × magnification mask, the interval Pa is 4 times the interval Ta (Pa = 4 × Ta), and when the photomask 11a is an equal size mask, the interval Pa is equal to the interval Ta. (Pa = Ta).

The inspection pattern 17 for inspecting the orthogonality of the stage moving axis is obtained by transferring the inspection pattern 14 of the photomask 11b. Therefore, the inspection pattern 17 is configured by arranging eight linear bar-like patterns having the same thickness at a constant interval Pb.
Here, the interval Pb of the inspection pattern 17 corresponds to the interval Tb of the inspection pattern 14. For example, when the photomask 11b is a 4 × magnification mask, the interval Pb is four times the interval Tb (Pb = 4 × Tb), and when the photomask 11b is an equal magnification mask, the interval Pb is equal to the interval Tb. (Pb = Tb).

The inspection patterns 16 and 17 are arranged and formed at both end portions of each side of the drawing pattern forming area 15, and the straight bar-like patterns constituting the inspection patterns 16 and 17 are respectively provided in the drawing pattern forming area 15. It is arranged perpendicular to the side.
When transferring from the photomask 11b to the cell CLc, the end of the inspection pattern 17 provided on the X axis direction minus side of the cell CLc and the inspection provided on the X axis direction plus side of the cell CLa. The cells CLa and CLc are aligned in the X-axis direction so that the ends of the pattern 16 are adjacent to each other along the straight line w parallel to the Y-axis.

Here, the arrangement and intervals Pa and Pb of the test patterns 16 and 17 are such that the test pattern 16 constitutes a caliper main scale (main scale) and the test pattern 17 is a caliper vernier (vernier). What is necessary is just to set suitably so that it may comprise.
In the example shown in FIG. 3 and FIG. 4, by setting the interval Pa to 10 μm and the interval Pb to 9.9 μm, based on the Vernier principle, the linear bar-like patterns of the inspection patterns 16 and 17 are calibrated, The positional deviation between the inspection patterns 16 and 17 can be visually measured with an accuracy of 0.05 μm.
Then, by visually measuring the positional deviations of the inspection patterns 16 and 17 formed in the adjacent portions of the cells CLa and CLc, the X axis of the stage moving axis is determined from the positional deviation of the inspection patterns 16 and 17. It is possible to detect a shift in the arrangement of the cells CLa and CLc with respect to.

  Therefore, with respect to the portion α shown in FIG. 2, the inspection patterns 16 and 17 on the positive side in the Y-axis direction of the cells CLa and CLc are visually observed using a metal microscope, thereby arranging the cells CLa and CLc. Detecting the deviation.

FIG. 3 shows a case where there is no deviation in the arrangement of the cells CLa and CLc, and FIG. 3B is an enlarged view in the vicinity of the portion β shown in FIG.
As shown in FIG. 3B, when the center line n of the center pattern 16a of the test pattern 16 and the center lines r of the two test patterns 17 opposed to each other match each cell CLa. , It can be seen that there is no deviation in the CLc sequence.
In other words, when the cells CLa and CLc are not misaligned, the arrangement of the patterns 16 and 17 and the intervals Pa and Pb are set so that the center lines n and r match each other. .

FIG. 4 shows a case where the arrangement of the cells CLa and CLc is misaligned, and FIG. 4B is an enlarged view in the vicinity of the portion β shown in FIG.
As shown in FIG. 3B, when the center line s of the central pattern 16a of the inspection pattern 16 and the adjacent pattern in the drawing coincide with the center line u of the inspection pattern 17 opposite thereto. It can be seen that the cell CLc is shifted to the positive side in the Y-axis direction by 0.05 μm with respect to the cell CLa.
At this time, since only the length of the central pattern 16a of the test pattern 16 is larger than the other patterns, the positional deviation between the test patterns 16 and 17 can be easily observed visually.

Similarly, with respect to the portion γ shown in FIG. 2, each of the cells CLa, CLc is observed by visual observation using a metal microscope on each of the test patterns 16, 17 on the minus side in the Y-axis direction of each cell CLa, CLc. Detection of deviation of CLc sequence.
Here, the displacement values of the arrays of the cells CLa and CLc detected for the portions α and γ should be equal, but depending on the transfer accuracy of the test patterns 16 and 17, an error occurs in the displacement value. There is a fear.
Therefore, if an average value of the deviations of the arrangements of the cells CLa and CLc detected for the portions α and γ is taken, it is possible to correct an error due to the transfer accuracy of the test patterns 16 and 17. Therefore, it is possible to accurately obtain the deviation of the arrangement of the cells CLa and CLc.

Next, in the same manner as the cells CLa and CLc, a shift in the arrangement of the cells CLa and CLb is detected.
Then, based on the deviation of the arrangement of the cells CLa and CLc and the deviation of the arrangement of the cells CLa and CLb, the angle of the deviation of the arrangement of the cells CLa to CLc with respect to the X axis of the stage movement axis (θx shown in FIG. 13). )) Is detected.

Here, it is possible to detect the angle of the deviation of the arrangement of the cells CLa to CLc with respect to the X axis of the stage moving axis only by one of the deviation of the arrangement of the cells CLa and CLc or the deviation of the arrangement of the cells CLa and CLb. However, depending on the transfer accuracy of each of the cells CLa to CLc, an error may occur in the detected value of the deviation angle.
Therefore, with respect to the cell CLa arranged at the center of the XY axis, the deviation of the arrangement of the cells CLc arranged on the plus side in the X axis and the deviation of the arrangement of the cells CLb arranged on the minus side in the X axis direction. Since the error due to the transfer accuracy of each of the cells CLa to CLc can be corrected, each cell CLa with respect to the X axis of the stage moving axis can be corrected. The angle of deviation of the arrangement of ~ CLc can be accurately obtained.

Subsequently, in the same manner as the cells CLa and CLc, the deviation of the arrangement of the cells CLa and CLd and the deviation of the arrangement of the cells CLa and CLe are detected.
Then, based on the deviation of the arrangement of the cells CLa, CLd and the deviation of the arrangement of the cells CLa, CLe, the angle of the deviation of the arrangement of the cells CLa, CLd, CLe relative to the Y axis of the stage movement axis (see FIG. 13). (See θy ° shown).

Here, only one of the deviation of the arrangement of the cells CLa and CLd or the deviation of the arrangement of the cells CLa and CLe detects the angle of deviation of the arrangement of the cells CLa, CLd and CLe with respect to the Y axis of the stage movement axis. However, depending on the transfer accuracy of each of the cells CLa, CLd, and CLe, an error may occur in the detected value of the deviation angle.
Therefore, with respect to the cell CLa arranged at the center of the XY axis, the deviation of the arrangement of the cells CLe arranged on the Y axis direction plus side and the deviation of the arrangement of the cells CLd arranged on the Y axis direction minus side. If the average value of each deviation is taken and the error due to the transfer accuracy of each cell CLa, CLd, CLe can be corrected, each stage movement axis relative to the Y axis can be corrected. It is possible to accurately determine the angle of deviation of the arrangement of the cells CLa, CLd, and CLe.

  As described in detail above, in the first embodiment, for each cell CLa to CLe transferred and formed on the semiconductor wafer WF, each cell CLa to CLe is determined from each test pattern 16 and 17 provided in each cell CLa to CLe. Is detected, the angle of the shift of the arrangement of the cells CLa to CLe with respect to the XY axis of the stage movement axis is obtained based on the deviation of the arrangement, and the deviation of the orthogonality of the stage movement axis is detected based on the obtained angle. .

When it is detected that the orthogonality of the stage movement axis is shifted, the exposure processing of the semiconductor wafer WF is stopped in a state where the transfer of each of the cells CLa to CLe is finished, and the semiconductor wafer WF is removed. In addition to being discarded as a defective product, inspection and maintenance are performed in order to investigate troubles of parts and the like of the exposure apparatus, and after the deviation of the orthogonality of the stage moving axis is eliminated, the exposure processing of a new semiconductor wafer WF is resumed.
Further, when it is detected that there is no deviation in the orthogonality of the stage movement axis, the exposure processing of the semiconductor wafer WF is performed as usual using the photomask 11b for the cells other than the cells CLa to CLe. Let it continue.

  As described above, since the inspection method of the first embodiment can be executed online during the exposure process of the semiconductor wafer as the product, troubles such as parts of the exposure apparatus suddenly occur, and the exposure process of the semiconductor wafer as the product occurs. Even if a deviation occurs in the orthogonality of the stage movement axis, it is possible to grasp the deviation during product processing, and a defective semiconductor wafer in which the alignment accuracy of each cell is reduced as in the conventional technology Is not manufactured as a finished product.

In addition, in the first embodiment, unlike the conventional inspection method, it is not necessary to periodically inspect the inspection wafer and the dedicated measuring machine as the inspection equipment. Compared with the conventional inspection method, the manufacturing cost of the semiconductor wafer can be reduced by the time required for the process.
Therefore, according to the first embodiment, an exposure method that can accurately detect the orthogonality of the stage movement axis of the exposure apparatus during the exposure process can be provided at low cost.

  In the first embodiment, since the inspection patterns 16 and 17 are arranged and formed in the scribe region SL, the drawing pattern formed in the drawing pattern formation region 15 of each cell CLa to CLe is the inspection pattern. No restrictions are imposed by 16,17.

Second Embodiment
FIG. 5 is a plan view showing the main configuration of the photomasks 21a and 21b used in the second embodiment.
Each of the photomasks 21a and 21b differs from the photomasks 11a and 11b of the first embodiment in that each of the inspection patterns 13 and 14 is formed only at one appropriate position on each side of the drawing pattern forming region 12. Just a point.

FIG. 6 is a plan view showing a main configuration of the semiconductor wafer WF on which the cells CLa to CLe are formed in the second embodiment.
In the second embodiment, in each of the cells CLa to CLe, the test patterns 16 and 17 are formed at only one appropriate position on each side of the drawing pattern forming region 15.

Therefore, in the second embodiment, the transfer accuracy of each of the inspection patterns 16 and 17 is higher than that of the first embodiment in which the inspection patterns 16 and 17 are formed at both ends of each side of the drawing pattern forming region 15. Although there is a possibility that the detection accuracy of the misalignment of the cells CLa to CLe may be reduced due to the influence, the same operations and effects as those in the first embodiment are obtained.
According to the second embodiment, the area of the scribe region SL where the test patterns 16 and 17 are not provided is wider than that of the first embodiment, and therefore various test patterns and the like are provided in the portion. There is an advantage that it can be used effectively.

<Third Embodiment>
FIG. 7 is a plan view showing a main configuration of photomasks 31a and 31b used in the third embodiment.
Each photomask 31a, 31b is different from the photomask 11a, 11b of the first embodiment in that each inspection pattern 13, 14 is formed over the entire circumference of each side of the drawing pattern forming region 12. Only.

FIG. 8 is a plan view showing the main configuration of the semiconductor wafer WF on which the cells CLa to CLe are formed in the third embodiment.
In the third embodiment, the test patterns 16 and 17 are formed over the entire circumference of each side of the drawing pattern forming region 15 in each of the cells CLa to CLe.
Therefore, also in 3rd Embodiment, the effect | action and effect similar to 1st Embodiment are acquired.

<Fourth embodiment>
FIG. 9 is a plan view showing a main configuration of photomasks 41a and 41b used in the fourth embodiment.
Each of the photomasks 41a and 41b differs from the photomasks 11a and 11b of the first embodiment only in that the inspection patterns 13 and 14 are formed at appropriate positions in the drawing pattern formation region 12. .

FIG. 10 is a plan view showing the main configuration of the semiconductor wafer WF on which the cells CLa to CLe are formed in the fourth embodiment.
In the fourth embodiment, in each of the cells CLa to CLe, the test patterns 16 and 17 are formed at appropriate locations in the drawing pattern forming region 15.
Therefore, the fourth embodiment has an advantage that various test patterns can be formed in the scribe area SL and used effectively compared to the first embodiment in which the inspection patterns 16 and 17 are formed in the scribe area SL. There is.

FIG. 11 is a plan view showing the vicinity of adjacent portions of the test patterns 16 and 17 on the plus side in the Y-axis direction of the cells CLa and CLc in the fourth embodiment.
In the fourth embodiment, the inspection patterns 16 and 17 are formed in the drawing pattern forming region 15 and the inspection patterns 16 and 17 are separated from each other. Therefore, the inspection patterns 16 and 17 are adjacent to each other. As in the first embodiment, the positional deviation between the inspection patterns 16 and 17 cannot be directly visually measured.

  Therefore, in the fourth embodiment, a scale line D is provided in the finder of the metal microscope, one end of the scale line D is matched with each inspection pattern 16, and the scale is located on the extension of each inspection pattern 16. By visually measuring the positional deviation between the other end of the line D and the inspection pattern 17, the positional deviation of each of the inspection patterns 16 and 17 is visually measured indirectly via the scale line D.

<Another embodiment>
The present invention is not limited to the above-described embodiments, and may be embodied as follows. Even in this case, operations and effects equivalent to or higher than those of the above-described embodiments can be obtained.

[1] In the first embodiment, as shown in FIGS. 3 and 4, the ends of the test patterns 16 and 17 are adjacent to each other on a straight line w parallel to the Y axis.
However, as shown in FIG. 12, the test patterns 16 and 17 may be arranged so that the end portions of the test patterns 16 and 17 are separated with the straight line w interposed therebetween.
In this case, similarly to the fourth embodiment, a scale line D that coincides with the inspection pattern 16 is provided in the finder of the metal microscope, and each inspection pattern 16, 17 is indirectly connected via the scale line D. It is only necessary to visually measure the positional deviation.

[2] In the fourth embodiment, the cell CLa and the cells CLb and CLc are adjacent to each other, and the cell CLa and the cells CLd and CLe are adjacent to each other.
However, the cell CLb may be spaced from the minus side in the X-axis direction and the cell CLc may be spaced from the plus side in the X-axis direction.
In addition, the cell CLd may be arranged to be separated from the minus side in the Y axis direction with respect to the cell CLa, and the cell CLe may be arranged to be separated from the plus side in the Y axis direction.

  [3] Each of the above embodiments is applied to a technique for transferring and forming each cell on the semiconductor wafer WF. However, the present invention is not limited to a semiconductor wafer and may be applied to a substrate of any material as long as it is a technique for transferring and forming a plurality of identical drawing patterns on a substrate, and is not limited to a cell of a semiconductor device. Any drawing pattern may be applied.

The top view which shows the principal part structure of the photomasks 11a and 11b used by 1st Embodiment which actualized this invention. The top view which shows the principal part structure of the semiconductor wafer WF in which each cell CLa-CLe was formed in 1st Embodiment. FIG. 3A is a plan view showing the vicinity of adjacent portions of the test patterns 16 and 17 on the plus side in the Y-axis direction of the cells CLa and CLc in the first embodiment, and is an enlargement of the portion α shown in FIG. Figure. FIG. 3B is an enlarged view of the vicinity of the portion β shown in FIG. FIG. 4A is a plan view showing the vicinity of adjacent portions of the test patterns 16 and 17 on the positive side in the Y-axis direction of the cells CLa and CLc in the first embodiment, and is an enlargement of the portion α shown in FIG. Figure. FIG. 4B is an enlarged view of the vicinity of the portion β shown in FIG. The top view which shows the principal part structure of the photomasks 21a and 21b used by 2nd Embodiment which actualized this invention. The top view which shows the principal part structure of the semiconductor wafer WF in which each cell CLa-CLe was formed in 2nd Embodiment. The top view which shows the principal part structure of the photomasks 31a and 31b used by 3rd Embodiment which actualized this invention. The top view which shows the principal part structure of the semiconductor wafer WF in which each cell CLa-CLe was formed in 3rd Embodiment. The top view which shows the principal part structure of the photomasks 41a and 41b used by 4th Embodiment which actualized this invention. The top view which shows the principal part structure of the semiconductor wafer WF in which each cell CLa-CLe was formed in 4th Embodiment. The top view which shows the adjacent part vicinity of each test pattern 16 and 17 in the Y-axis direction plus side of each cell CLa and CLc in 4th Embodiment. The top view which shows the adjacent part vicinity of each test pattern 16 and 17 in the Y-axis direction plus side of each cell CLa and CLc in the other example of 1st Embodiment. When a deviation occurs in the orthogonality of the stage movement axis (θx ° with respect to the X axis and θy ° with respect to the Y axis), a deviation also occurs in the arrangement of the cells CL formed on the semiconductor wafer WF. FIG.

Explanation of symbols

11a, 21a, 31a, 41a ... first photomask 11b, 21b, 31b, 41b ... second photomask 12, 15c ... drawing pattern formation region 13, 16 ... first inspection pattern 14, 17 ... second inspection pattern
CLa ... 1st cell
CLb, CLc ... 2nd cell
CLd, CLe ... third cell Ta, Tb, Pa, Pb ... spacing
WF ... Semiconductor wafer (substrate)
SL ... Scribe area D ... Scale line

Claims (6)

In the exposure method of scanning the entire surface of the substrate while repeating shot exposure and transferring the photomask drawing pattern onto the substrate,
The first cell transferred from the first photomask onto the substrate is provided with a first inspection pattern in addition to the drawing pattern forming area where the drawing pattern is formed,
The second cell and the third cell, which are transferred from the second photomask onto the substrate, are provided with a second inspection pattern in addition to the drawing pattern formation region in which the same drawing pattern as the first cell is formed. ,
The center of the first cell coincides with the center point of the XY axis where the X axis and the Y axis of the stage movement axis of the exposure apparatus are orthogonal,
The second cell is arranged in the X-axis direction with respect to the first cell,
The third cell is arranged in the Y-axis direction with respect to the first cell,
Based on Vernier's principle in which the first inspection pattern is the main scale and the second inspection pattern is the sub scale, from the positional deviation between the first inspection pattern of the first cell and the second inspection pattern of the second cell, Detecting the displacement of the arrangement of the first cell and the second cell with respect to the X axis;
Based on the vernier principle, the displacement of the arrangement of the first cell and the third cell with respect to the Y axis is detected from the positional deviation of the first inspection pattern of the first cell and the second inspection pattern of the third cell;
An exposure method, comprising: detecting an orthogonality of a stage moving axis based on a displacement of an arrangement of a first cell, a second cell, and a third cell. The exposure method according to claim 1, wherein
The second cell is composed of a cell disposed on the negative side in the X-axis direction with respect to the first cell, and a cell disposed on the positive side in the X-axis direction with respect to the first cell,
The third cell includes a cell disposed on the negative side in the Y-axis direction with respect to the first cell and a cell disposed on the positive side in the Y-axis direction with respect to the first cell. An exposure method characterized by the above. In the exposure method according to claim 1 or 2,
The exposure method, wherein the first inspection pattern and the second inspection pattern are arranged in a scribe region provided between the cells. The exposure method according to claim 3, wherein
The drawing pattern formation region of each cell has a rectangular shape,
The exposure method, wherein the first inspection pattern and the second inspection pattern are arranged at both end portions of each side of the drawing pattern formation region. The exposure method according to claim 3, wherein
The drawing pattern formation region of each cell has a rectangular shape,
The exposure method according to claim 1, wherein the first inspection pattern and the second inspection pattern are arranged at an appropriate position on each side of the drawing pattern formation region. In the exposure method according to claim 1 or 2,
The exposure method, wherein the first inspection pattern and the second inspection pattern are arranged in the drawing pattern formation region of each cell.

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