JP6718225B2 - Photomask and manufacturing method thereof - Google Patents

Description

The present invention relates to a photomask blank mainly used for a flat panel display and the like and a photomask using the same.

In the manufacturing process of electronic devices such as flat panel displays, a multi-tone photomask called a halftone mask (or a graytone mask) is used in order to reduce the number of lithography processes and reduce the manufacturing cost. .. The halftone mask is composed of a transmissive part, a light-shielding part, and a semi-transmissive part having a light transmittance between the transmissive part and the light-shielding part, and the exposure amount of the photoresist to be transferred is different in one exposure. A pattern can be formed.

When manufacturing such a halftone mask, it is necessary to draw a plurality of patterns on one photomask blank in order to pattern the light-shielding film and the semi-transmissive film, respectively. To form a plurality of patterns, it is necessary to overlap the patterns. Therefore, when the first pattern is drawn on the photomask blank by the drawing device, the alignment mark is also drawn at the same time, and when the second pattern is drawn by the drawing device, the alignment mark is aligned and the second pattern is drawn. To draw.

In addition, the manufacturing process of the electronic device that is a product includes a plurality of lithography processes using different photomasks, and the pattern formed in the preceding lithography process is superimposed on the pattern formed in the preceding lithography process. There is a need.

When manufacturing a photomask used in such a lithography process, the pattern shape to be drawn, the manufacturing cost, and the delivery time are taken into consideration, and the photomask is manufactured using an optimum drawing apparatus for manufacturing each photomask. Also, at the photomask manufacturing site of a mask manufacturer, in order to promise delivery time to the device manufacturer who is the customer, throughput is increased, and more importantly, multiple drawing devices are used to cope with unexpected device failures. We secure a table and manufacture photomasks. If a photomask is manufactured using the same drawing apparatus, for example, the photomask must be manufactured only in one drawing apparatus that can draw the finest pattern in the electronic device manufacturing process. This will increase the cost and make it impossible to guarantee the delivery date.

JP, 2014-81409, A JP, 2013-222811, A

Conventionally, in a photomask that needs to draw a plurality of patterns such as a halftone mask, an overlay error (alignment error) occurs when drawing each pattern. Further, for example, when a transfer pattern for manufacturing a product is drawn on a photomask, an error occurs in the transferred pattern itself depending on the drawing device. For example, even if the same pattern is drawn by drawing devices manufactured by different device makers, errors such as size variation and shape distortion occur.

The characteristics of the errors in drawing these patterns (the error of the pattern itself and the overlay error) differ depending on the device that actually draws the pattern. Therefore, it is very difficult to match the characteristics of these errors between different drawing apparatuses, and it is impossible to substantially match the characteristics of these errors especially when the manufacturers of the drawing apparatuses are different.

In order to improve the overlay accuracy of the patterns, Document 1 discloses a method of matching the positional deviation tendency of the patterns and improving the overlay accuracy. However, since the same photomask is used to form different patterns and the applicable patterns are limited, it is impossible to apply it to the process of manufacturing actual products having various patterns. Further, a method of preventing an alignment error in the manufacturing process of a halftone mask is also disclosed, but it requires a combination of a provisional pattern and a secondary drawing pattern, and the pattern formation is very complicated and applicable pattern. However, it is impossible to apply it to the manufacturing process of real products.

Further, Document 2 only discloses a technique of improving the overlay accuracy by improving the alignment mark detection accuracy, and the overlay accuracy of patterns drawn by different drawing devices having different overlay error characteristics. There is no disclosure of a technique for improving the.

None of the documents discloses a technique for reducing an overlay error between different drawing devices having different error characteristics, and does not mention a technique for reducing a pattern error.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a photomask blank that can realize a precise transfer pattern with high alignment accuracy even if a different drawing device is used.

Photomask blanks according to the present invention,
It has at least four alignment patterns located at the vertices of a quadrangle,
Reference data information consisting of coordinate positions of each of the alignment patterns,
It is characterized in that it is associated with the coordinate position recorded in itself or the identification information for identifying itself.

Equipped with each alignment pattern that serves as a reference, and the reference data information of the coordinate position actually measured for each alignment pattern is associated with the photomask blanks, so the characteristics of the error in the transfer pattern during photomask manufacturing are matched. Therefore, a multi-tone photomask such as a halftone mask with a reduced overlay error can be manufactured.

The four alignment patterns are a first reference spaced apart by a first distance and a second distance from the intersecting first and second sides of the four sides forming the end surface of the photomask blank. Points and
A second reference point separated from the second side and the first reference point by a third distance and a fourth distance, respectively;
A third reference point separated from the first reference point by a fifth distance in a vertical direction to a reference side connecting the first reference point and the second reference point,
It is characterized in that it is located at a fourth reference point that is separated from the second reference point by a sixth distance in a direction perpendicular to the reference side.

By setting the reference point according to the procedure determined as described above, it is possible to form the reference alignment pattern even when the external dimension accuracy of the substrate of the photomask blank is poor.

Photomask blanks according to the present invention,
The coordinate position of each of the alignment patterns,
The relative coordinate position of each of the alignment patterns, or the relative coordinate position and the absolute coordinate position measured after the formation of the alignment pattern is provided.

Since the coordinate position of each alignment pattern is provided with the relative coordinate position actually measured after the alignment pattern is formed, or the relative coordinate position and the absolute coordinate position, it is possible to compare with the measurement data of the coordinate position measured in the drawing device, Extracts differences in data and enables scaling, distortion correction, or rotation correction.

The photomask manufacturing method according to the present invention is
A first step of preparing a photomask blank having at least four alignment patterns located at the vertices of a quadrangle, and associated with reference data information consisting of coordinate positions of the respective alignment patterns ;
A second step of inputting the reference data information ,
A third step of outputting the coordinate position before the SL each alignment pattern as measured drawing device data information by the pattern writing apparatus,
A fourth step of correcting a pattern to be drawn on the photomask blank based on the reference data information and the drawing device data information,
Characterized in that it comprises a fifth step of drawing a corrected pattern in the fourth step in the photomask blank by the pattern drawing device.

In the above photomask manufacturing method, since the pattern to be transferred to the product is corrected by the reference data information associated with the photomask blanks, it is possible to provide a photomask in which the overlay error and the transfer pattern error are greatly improved. It is possible.

A group of photomasks according to the present invention comprises:
Each has at least four alignment patterns located at the vertices of a quadrangle,
Reference data information of the coordinate position of each alignment pattern is associated,
For multiple photomask blanks,
It is characterized in that it includes a plurality of photomasks on which different patterns are drawn.

The different pattern is a pattern in which a coordinate position of each alignment pattern of the photomask blank is corrected by a coordinate position measurement value measured by a pattern drawing device and the reference data information.

A plurality of photomasks each having a pattern to be transferred to a product drawn on a photomask blank having an alignment pattern and associated with reference data information of its coordinate position are used as a group of photomasks in the manufacturing process of the product. As a result, even if the photomasks are formed by using the drawing apparatuses of different manufacturers, the overlay accuracy in the plurality of lithography steps for manufacturing the product is significantly improved, and the electronic devices mounted on the product can be High integration and high performance can be achieved.

By providing a photomask blank having a reference alignment pattern and further associated with data information of coordinate positions of each alignment pattern, the photomask blank is used as a customer of the photomask manufacturer. When the transfer pattern requested by the device maker is drawn, the drawing pattern can be corrected based on a uniform standard, and alignment errors and pattern errors can be reduced. As a result, a highly accurate multi-tone photomask can be realized. Furthermore, by using a group of masks composed of a plurality of photomasks manufactured by using the photomask blanks of the present invention, it is possible to reduce an overlay error when manufacturing a product and to highly integrate electronic devices mounted on the product. Enable.

FIG. 6 is a plan view illustrating a process of setting the arrangement position of the alignment pattern on the photomask blank of the present invention. The top view which shows the arrangement position of the alignment pattern of this invention. Sectional drawing which shows the process of forming the alignment pattern of this invention. The top view which shows the shape example of the alignment pattern of this invention. Sectional drawing which shows the process of forming the alignment pattern of this invention. FIG. 6 is a plan view showing the effects of scaling and distortion correction according to the present invention. The top view which shows the effect of rotation correction by this invention.

Embodiments of the present invention will be described below with reference to the drawings. However, none of the following embodiments gives a limited interpretation in the recognition of the gist of the present invention. Further, the same or similar members are given the same reference numerals, and the description thereof may be omitted.

(Alignment pattern placement method)
FIG. 1 is a plan view showing a process of setting an arrangement position of an alignment pattern of a photomask blank according to the present invention.

As shown in FIG. 1A, a first distance d1 and a second distance (3) from a first side (2) and a second side (3) intersecting each other among the four sides forming the end surface of the photomask blank (1), respectively. A first reference point (4) separated by a second distance d2 is determined.

At this time, the first reference point (4) is an area (hereinafter referred to as a transfer pattern exposure area (5)) in which a pattern (hereinafter referred to as a transfer pattern) to be transferred to a product to be manufactured using a photomask is formed. The distance from the first side (2) and the second side (3) is set so as to be located on the outer peripheral side. Therefore, the alignment pattern formed on the photomask blanks (1) does not affect the pattern formation during device manufacturing.

Next, as shown in FIG. 1B, the second distance (3) is separated from the second side (3) by a third distance d3, and the second distance d4 is separated from the first reference point (4) by a second distance d4. The reference point (6) is set. Here, a straight line connecting the first reference point (4) and the second reference point (6) is defined as a pattern reference side (7). The length of the pattern reference side (7) is equal to the fourth distance d4. The second distance d2 and the third distance d3 are set to the same value, but they may be set to different values in consideration of the distortion of the outer shape of the mask blank.

Next, as shown in FIG. 1C, a third reference point (8) separated from the first reference point (4) by a fifth distance d5 in the direction perpendicular to the pattern reference side (7), and A fourth reference point (9), which is separated from the second reference point (6) by a sixth distance d6 in the direction perpendicular to the pattern reference side (7), is set on the photomask blank (1).

Note that the vertical direction is set by the XY stage of the drawing apparatus, and therefore, actually, within the accuracy (range of error) of the moving mechanism of the drawing apparatus, there is a deviation from a strict 90°. May occur. Further, the fifth distance d5 and the sixth distance d6 are set to the same value, but the fifth distance and the sixth distance d6 are set for calibration of the drawing apparatus for drawing the alignment pattern of the photomask blanks (1). The distance and the distance may be set to different values.

At the reference point set by the above procedure, an alignment pattern is formed by the method described later, and the photomask blanks (1) having the alignment pattern are manufactured. At this time, a mark for identifying the first reference point (4) and the pattern reference side (7) is also created. If this mark has no influence on the transfer pattern and the alignment pattern, the positional accuracy and the like are irrelevant.

Next, the relative coordinate position of each alignment pattern is measured with respect to the photomask blank (1) on which the alignment pattern has been formed, and is managed (stored) as data information associated with the photomask blank (1). Further, the absolute coordinate position of each alignment pattern is calculated from the distance between the end face of the photomask blank (1) and the alignment pattern and the relative coordinate position, and is also managed (stored as data information associated with the photomask blank (1)). ) Do. That is, the data information consisting of relative and absolute coordinate positions of each alignment pattern (hereinafter referred to as reference data information) is not the setting value of the coordinate position forming each alignment pattern, but using the drawing device or the coordinate measuring device, The actually measured values are associated with the photomask blanks (1). Therefore, even when the coordinate position is measured by the drawing device, the coordinate position is measured again after the alignment pattern is formed. Here, as the coordinate measuring device, a defect inspection device can be used, but the coordinate measuring device is not limited to this.

Since the relative coordinates of each alignment pattern are known, for example, the accurate distance between the two alignment patterns is also known, and the accurate angle of each vertex of a quadrangle whose vertex is each alignment pattern is also known. Means

As a method of managing reference data information by associating it with photomask blanks (or associating method), identification information (for example, serial number) for uniquely identifying each individual photomask blank itself and reference data information are associated with each other. Etc. (for example, the serial number is used as the file name for storing the reference data information), or the coordinate position is directly drawn (or described) using the photomask blank itself as the recording medium. The position and the reference data information may be associated (in this case, the same), and the association method is not particularly limited. When the reference data information is directly drawn, characters (numerals) may be drawn, or it may be drawn in a symbolized form such as a one-dimensional or two-dimensional barcode.

Therefore, one piece of identification information is given to one photomask blank, and one piece of reference data information is associated with (corresponding to) this identification information. When a photomask blank is specified, the photomask blank is identified. This means that the reference data information corresponding to the blanks can be uniquely specified and the reference data information can be obtained (read). Further, when the coordinate position (reference data information) is described in the photomask blank, it goes without saying that the reference data information can be uniquely specified by specifying the photomask.

The method for arranging the alignment pattern is an example, and the method is not limited to this. According to a predetermined procedure determined by the drawing device for forming the alignment pattern, the alignment pattern is arranged at the apex of the quadrangle on the outer peripheral side of the transfer pattern exposure region of the photomask blank, and the accurate coordinate position of each alignment pattern (at least The data information of the relative coordinates) may be managed (stored) in association with the photomask blanks.

Since the fixed procedure is determined as described above and the alignment pattern is arranged in accordance with the fixed procedure, even if the outer shape accuracy of the photomask blank is poor and the outer dimension varies, the relative coordinate position of the quadrangle 4 is set accurately. A photomask blank having an alignment pattern at one vertex can be provided.

As described above, the photomask blank according to the present invention can be regarded as a set of the photomask blank and the reference data information of the alignment pattern. Then, a plurality of such groups are prepared and stored as an inventory or shipped to a photomask maker for use in manufacturing a photomask. The effect of improving the transfer pattern accuracy by using such a set configuration will be described later.

In the above embodiment, the basic alignment pattern (hereinafter referred to as the basic alignment pattern (10)) is arranged at the four reference points of the photomask blank (1), but as shown in FIG. The first auxiliary pattern (11) may be added to the center of the adjacent reference points of the second, third, and fourth reference points, and if the formation of the transfer pattern is not affected, the transfer pattern exposure area You may arrange|position an alignment pattern in it. For example, the second auxiliary pattern (12) may be added to the center of the photomask. When the number of alignment patterns to be arranged is large, the coordinates can be referred to at a short distance, so that the accuracy of the transfer pattern of the photomask is further improved.

(Alignment pattern forming method)
Hereinafter, a method of forming an alignment pattern on a photomask blank will be described by taking a halftone mask as an example.

First, as shown in FIG. 3A, a light shielding film (14) made of a metal film such as chromium is formed on a transparent substrate (13) such as quartz glass having a thickness of 40 nm, for example. A known film forming method such as a sputtering method can be used for forming the film.

Next, as shown in FIG. 3B, a photoresist is applied, exposed by an exposure device, and then developed to form a photoresist pattern (15) having an alignment pattern shape. The photoresist pattern may be formed not only by exposure by an exposure device but also by development after being drawn by a laser drawing device or the like.

Next, as shown in FIG. 3C, the light shielding film (14) is etched using the photoresist pattern (15) as a mask, and then the photoresist pattern (15) is removed by ashing or the like to remove the light shielding film pattern (14a). ) Is formed.

Through the above steps, a photomask blank for a binary mask is completed. Although the above is the film structure of only the light-shielding film, a photomask blank for a binary mask may be manufactured by using only a semi-transmissive film or a phase shift film instead of the light-shielding film. In the case of a photomask blank for a halftone mask, it is necessary to further form a semitransparent film. That is, after the step of FIG. 3C, the alignment pattern portion is shielded, and a semitransparent film of chromium oxide or the like is formed on the upper layer by a sputtering method or the like to have a thickness of 20 nm, for example. As a result, a photomask blank for a halftone mask having a semi-transmissive film on the upper layer of the light shielding film is completed.

FIGS. 4A and 4B are plan views showing an example of the alignment pattern shape in the step of FIG. 3C. As the alignment pattern shape, a cross shape as shown in FIG. 4A, a wedge shape as shown in FIG. 4B, or a combination of these shapes can be used. Since the centers of these patterns can be calculated from the pattern edges on both sides, the coordinate position of the alignment pattern can be specified without being affected by the line width variation.

In the case of a halftone mask having the semi-transmissive film 4 below the light-shielding film, the photomask blanks may be manufactured by the process shown in FIG.

That is, as shown in FIG. 5(a), a semi-transmissive film (16) of chromium oxide or the like is formed on a transparent substrate (13) of quartz glass or the like to have a thickness of 20 nm, for example, and then a metal film of chromium or the like is formed. The light shielding film (14) is formed with a thickness of 40 nm, for example.

Next, as shown in FIG. 5B, a photoresist pattern (17a) is formed, and a pattern of the light shielding film (14a) and the semi-transmissive film (16a) is formed by etching using the photoresist pattern (17a) as a mask. To do.

After that, as shown in FIG. 5C, the photoresist pattern (17a) is removed by ashing or the like, and a photomask blank for a halftone mask having a semi-transmissive film under the light-shielding film is completed.

Further, in FIG. 5, by changing the order of forming the semi-transmissive film (16) and the light-shielding film (14) formed on the transparent substrate (13), a half-tone mask provided with a semi-transmissive film as an upper layer of the light-shielding film. Photomask blanks can be obtained.

Further, in the above embodiment, the method of forming the alignment pattern in the halftone mask having the laminated structure film of the semi-transmissive film and the light-shielding film has been described, but the phase shift mask using the phase shift film instead of the semi-transmissive film is described. Also, the alignment pattern can be formed by the same method. Thereby, a photomask blank for a phase shift mask having an alignment pattern can be provided.

The shape of the alignment pattern may be a pattern shape compatible with both the alignment mark detection method of the drawing apparatus and the mark detection method of the coordinate measurement apparatus, or the pattern shapes suitable for each detection method may be adjacent to each other. good.

(Transfer pattern correction)
Hereinafter, the effect of forming a set of photomask blanks and reference data information of the alignment pattern will be described in detail with reference to the drawings.

In the manufacturing process of the halftone mask, since a plurality of patterns are formed, the above-mentioned alignment pattern is used to perform superposition at the time of forming each pattern, which makes it possible to improve the superposition accuracy. Can be used to further improve the overlay accuracy.

The photomask blank is associated with reference data information actually measured for each alignment pattern formed according to the above-described determined procedure. By referring to this reference data information, various correction processes such as scaling, distortion, and rotation are performed on the drawing data of the transfer pattern for manufacturing the product. By using the corrected transfer pattern generated by the correction process, it is possible to draw a transfer pattern that accurately reproduces the design value even if the drawing device is different and the error characteristics are different.

That is, the drawing device for the pattern to be transferred measures the coordinate position of each alignment pattern, outputs it as drawing device data information, compares the drawing device data information with the reference data information of each alignment pattern, and determines the difference between the coordinate positions. Based on the above, various correction processes such as scaling, distortion and rotation are performed. The correction process will be specifically described below.

The characteristic of the coordinate accuracy of the drawing apparatus is due to the stage shape of the drawing apparatus. If the drawing device manufacturers (makers) are the same, the coordinate accuracy between the drawing devices can be matched to some extent, but it is difficult to match between the different drawing device manufacturers. Therefore, within the same drawing device manufacturer, even if the coordinate error between drawing devices is, for example, about ±0.3 μm, the error between drawing devices increases between different device manufacturers. It may be ±0.5 μm or more. The error in the coordinate accuracy appears as a distance between two points of the transfer pattern to be drawn or orthogonality, that is, an error in scaling or distortion.

For example, the dotted lines in FIGS. 6A and 6B schematically represent transfer patterns (18a, 18b) drawn by different drawing devices on the photomask blank (1) having no alignment pattern, for example, a rectangular pattern. It is a representation. The transfer patterns (18a, 18b) in FIGS. 6A and 6B deviate from a rectangular shape having four vertices at right angles, and each vertex has a distorted shape in which the angle deviates from 90°, It can be understood that the sizes of the opposite sides are different.

On the other hand, in the case of the photomask blank according to the present invention, reference data information including the reference basic alignment patterns (10) and their coordinate positions on the photomask blank (1) is different even for different drawing devices. It is the same (common). Therefore, the reference data information having the coordinate position of each alignment pattern (10) associated with the photomask blank (1) is input (read), and the coordinate position of each alignment pattern (10) is measured by the drawing device. It is possible to generate the coordinate position measurement value as the output as drawing device data information, compare the reference data information and the drawing device data information, and perform scaling correction and distortion correction. For example, for the distance between two points, the distance between two alignment patterns is compared by both data information, the difference is extracted, the scaling correction is performed so that the difference is minimized, and the angle of each vertex of the quadrangle formed by each alignment pattern is calculated using both data. It is also possible to perform distortion correction by comparing information and extracting a difference, and performing coordinate conversion so that the difference is minimized.

Note that the reference data information can be input (read) from the photomask blank by a drawing device or a defect inspection device when the reference data information is directly written on the photomask blank, and the reference data information can be stored in another recording medium or the like. If it is stored, it can be input (read) from the recording medium or the like by the control system of the drawing apparatus, the computer, or the like. The input method may be appropriately selected according to the storage form of the reference data information.

Note that FIG. 6 shows an example in which only the basic alignment pattern (10) is provided as an alignment pattern as described above for simplification, but other auxiliary patterns (11, 12) may be provided. Similarly, other auxiliary patterns (11, 12) may be provided in FIG. 7 described later.

By correcting the transfer pattern in this way, as shown in FIG. 6C, the desired transfer pattern (18c), in this case a rectangular pattern, is formed on the photomask blanks (1) even if a different drawing device is used. Can be drawn. As a result, it is possible to reduce the error to, for example, ±0.3 μm or less regardless of whether it is within the same device manufacturer or between different device manufacturers.

In addition, in order to improve the distortion shape of the transfer pattern exposed on the device by the exposure machine of the device manufacturer that is the destination of the manufactured photomask, the transfer pattern on the photomask is inversely corrected by scaling and distortion correction. It is also possible to do so. Also in this case, the drawing coordinates whose distortion is desired to be corrected may be calculated with reference to the alignment pattern of the photomask blank.

Further, the conventional drawing apparatus has a device configuration that detects four substrate end surfaces of the photomask blank and determines drawing position coordinates. However, the coordinate position includes an error of, for example, about ±0.5 mm depending on the detection accuracy of the substrate end surface. Therefore, the XY coordinate system itself of the drawing apparatus may cause an error (shift (parallel movement) or rotation) for each drawing apparatus with respect to the photomask blank. FIGS. 7A and 7B are plan views showing transfer patterns (19a, 19b) drawn by different drawing devices, for example, a rectangular pattern, on the photomask (1). The transfer patterns (19a, 19b) do not match with each other due to the deviation and the rotation error.

In the photomask blank (1) according to the present invention, the reference data information of the coordinate positions associated with the four basic alignment patterns (10) is the reference data information of the relative coordinate positions between the basic alignment patterns (10). , Reference data information of the absolute coordinate position from the substrate end surface of the photomask blank (1). Therefore, the coordinate position measurement value (drawing device data information) generated by the drawing device and the reference data information read as the information associated with the photomask blanks are used without changing the substrate end face detection mechanism of the conventional drawing device. Are compared, the difference between them is extracted, and the coordinate position data for drawing with the drawing device is corrected. For example, the difference between the coordinate positions of the reference data information and the drawing device data information can be corrected by minimizing the parallel movement and the coordinate rotation matrix.

By drawing the corrected transfer pattern (19c) on the photomask blank (1), it is possible to significantly reduce the coordinate position to 0.1 mm or less, and correct the coordinate position deviation and rotation.

These corrections are possible because the measured values are actually used as the reference data information of the coordinate position of the alignment pattern and the coordinate position data of the drawing device. The correction process may be executed by an arithmetic unit incorporated in the drawing apparatus, or may be executed by an external computer or the like by performing data communication between an external computer or the like and the drawing apparatus.

(Application to products)
Hereinafter, a method of applying a photomask manufactured using the photomask blank according to the present invention to a lithography process of a product will be described.

In actual product manufacturing, different patterns such as wirings and electrodes are transferred onto the product, and thus different photomasks are used in different lithography processes. Therefore, in the manufacture of one product, as many photomasks having different patterns as necessary to complete the electronic device are used. Since the patterns of each wiring and electrode must be electrically connected to each other, the overlay accuracy of the patterns transferred by the photomask corresponding to each pattern determines the degree of integration of electronic devices mounted on the product. It becomes one of the factors to do.

However, in each photomask, a pattern is formed by an appropriate different drawing device (or a drawing device of a different manufacturer) in consideration of the minimum size of each transfer pattern, the manufacturing cost, and the delivery time. Therefore, the characteristics of the error (scale, distortion, rotation) of the transfer pattern differ depending on the photomask, and become a factor that deteriorates the overlay error of each transfer pattern.

As described above, since the photomask blank according to the present invention has the alignment pattern and the reference data information thereof, it is possible to use a plurality of photomasks with different transfer patterns by using different drawing devices (even drawing devices of different manufacturers). Even when the mask is manufactured, the overlay accuracy of the transfer patterns is greatly improved, and the integration degree of electronic devices mounted on the product can be greatly improved.

Of all the photomasks used for manufacturing the product, at least a pattern (for example, element isolation, gate electrode, contact hole, first layer wiring, etc.) that influences the degree of integration of electronic devices mounted on the product is transferred. A plurality of photomasks for use as a group of photomasks, and by manufacturing these photomasks using the photomask blanks according to the present invention, the degree of integration of electronic devices is greatly improved, which contributes to improved product performance. can do. Of course, all photomasks may be manufactured using the photomask blanks according to the present invention.

That is, a plurality of photomask blanks having an alignment pattern and associated with the reference data information are prepared (or secured as an inventory), and the group of photomasks described above is used with these photomask blanks. By manufacturing, the characteristics of pattern error and overlay error can be matched even between different photomasks, and the high integration and miniaturization of electronic devices mounted on products can be improved, resulting in improved performance. Can be made.

The most preferable form of manufacturing a group of photomasks for manufacturing one product is to make a plurality of photomask blanks having a light-shielding film on at least a transparent substrate and to perform the same process according to a certain procedure as shown in FIG. With the drawing device, the alignment pattern is formed on each vertex of at least a quadrangle, the coordinate position of the alignment pattern is measured by the same coordinate measuring device, and the reference data information is associated with each photomask blank as the measurement output. The transfer pattern of each photomask of the photomask is drawn by an optimum drawing device, and at this time, each alignment pattern is measured by the optimum drawing device for each transfer pattern, and a drawing device that outputs the measurement output It is to correct each transfer pattern by comparing the data information with the reference data information. By using the same drawing device and the same coordinate measuring device, it is possible to draw the alignment pattern and measure the coordinate position with uniform accuracy and standard.

The alignment pattern drawing device and the transfer pattern drawing device do not have to be the same, and the transfer pattern drawing devices do not have to be the same. The optimum drawing apparatus may be selected in consideration of the manufacturing cost and the delivery date according to each transfer pattern.

1 Photomask Blanks 2 First Side 3 Second Side 4 First Reference Point 5 Transfer Pattern Exposure Area 6 Second Reference Point 7 Reference Side 8 Third Reference Point 9 Fourth Reference Point 10 Basic Alignment Pattern 11 First Auxiliary Pattern 12 Second Auxiliary Pattern 13 Transparent Substrates 14, 14a Light-shielding Film 15 Photoresist Patterns 16, 16a Semi-Transmissive Film 17a Photoresist Patterns 18a, 18b, 18c Transfer Patterns 19a, 19b, 19c Transfer Patterns

Claims (4)

A method of manufacturing a multi-tone photomask having a plurality of patterns, comprising:
A first step of preparing a photomask blank having at least four alignment patterns located at the vertices of a quadrangle, and associated with reference data information consisting of coordinate positions of the respective alignment patterns;
A second step of inputting the reference data information,
A third step of measuring the coordinate position of each of the alignment patterns by a first pattern drawing device and outputting it as first drawing device data information;
A fourth step of correcting the first pattern drawn on the photomask blank by comparing the reference data information with the first drawing apparatus data information;
A first pattern forming step including a fifth step of drawing the first pattern corrected in the fourth step on the photomask blank by the first pattern drawing device;
A sixth step of measuring the coordinate position of each alignment pattern by a second pattern drawing device and outputting it as second drawing device data information;
A seventh step of correcting the second pattern drawn on the photomask blank by comparing the reference data information and the second drawing device data information;
A second pattern forming step having an eighth step of drawing the second pattern corrected in the seventh step on the photomask blanks by the second pattern drawing device;
A method of manufacturing a multi-tone photomask, comprising: The four alignment patterns are a first reference spaced apart by a first distance and a second distance from the intersecting first and second sides of the four sides forming the end surface of the photomask blank. Points and
A second reference point separated from the second side and the first reference point by a third distance and a fourth distance, respectively;
A third reference point, which is separated from the first reference point by a fifth distance in a vertical direction to a reference side connecting the first reference point and the second reference point,
The method of manufacturing a photomask according to claim 1, wherein the photomask is located at a fourth reference point that is separated from the second reference point by a sixth distance in a direction perpendicular to the reference side. The coordinate position of each of the alignment patterns,
3. The photomask manufacturing method according to claim 1, further comprising a relative coordinate position, or a relative coordinate position and an absolute coordinate position, of each of the alignment patterns measured after forming the alignment pattern. 4. The method of manufacturing a photomask according to claim 1, wherein the pattern to be drawn on the photomask blank in the fourth step is subjected to scaling, distortion correction, and/or rotation correction.

Images