JP5288118B2 - Photomask blanks, photomask alignment method, and double-sided photomask manufacturing method - Google Patents

Description

  The present invention relates to a photomask blank for forming a light shielding pattern such as Cr (chromium) on both the front surface and the back surface in an effective area for exposure, and the position of the photomask using such a photomask blank. The present invention relates to an alignment method and a method for manufacturing a double-sided photomask.

  A photomask used as a master when projecting and exposing a semiconductor circuit onto a wafer is generally a light shielding pattern made of a metal such as Cr (chromium) or a metal compound such as MoSiN (molybdenum silicide nitride) on a glass substrate. Has a structure formed on one side thereof. However, in recent years, in order to realize finer processing, a photomask in which a light shielding pattern is formed on both the front surface and the back surface has been proposed. By the way, in such a photomask in which a light shielding pattern is formed on both sides, it is a technical problem to eliminate the deviation between the pattern on the front surface and the pattern on the back surface.

In order to cope with such a problem, Patent Document 1 (Japanese Patent Laid-Open No. 9-43860) discloses that a surface of the transparent substrate is patterned by photolithography on both the front and back surfaces of a transparent substrate such as a glass substrate. Double-side patterning characterized in that the alignment marker formed on the side is transferred to the back side, the back side is aligned based on the transferred alignment marker, and then the back side is patterned by photolithography The law is disclosed.
Japanese Patent Laid-Open No. 9-43860

  In the double-sided patterning method described in Patent Document 1, a method of transferring a front surface mark to the back surface is used. However, a transparent substrate generally having a thickness of 6.35 mm is generally used. Considering the distance of 6.35 mm when transferring to the back surface, a focus shift at the time of transfer occurs, a shift due to non-perpendicular transfer light occurs, or a light at the time of transfer In other words, the sharpness of the transfer mark is lowered due to the wraparound of the image, and there is a problem that the accuracy is deteriorated when the front and back patterns are aligned.

The present invention is for solving the above-mentioned problems. The invention according to claim 1 is directed to a transparent substrate, an alignment mark formed as a recess in one of the main surfaces of the transparent substrate, and the transparent substrate. photomask for the possess a light shielding film formed on different other main surface to the main surface, and forming a light shielding pattern on both surfaces of the main surface and the other main surface in the effective area for exposure A blank is characterized in that a light shielding film is not formed on the main surface .

The invention according to claim 2, in the photomask blank according to claim 1, wherein the alignment mark is carried out a pattern to be formed on the other main surface, the alignment of the pattern to be formed on the main surface It is characterized by being an alignment mark for front and back alignment.

According to a third aspect of the present invention, there is provided a transparent substrate, an alignment mark for front and back alignment formed as a recess in one of the principal surfaces of the transparent substrate, and another principal surface different from the principal surface of the transparent substrate. a light shielding film formed on said light shielding, and the resist film formed on the film have a, in an effective area for exposing said main surface for forming the light shielding pattern on both surfaces of the other major surface A step of preparing a photomask blank which is a photomask blank having no light-shielding film formed on the main surface, a step of drawing front and back alignment marks together with a predetermined pattern on the other main surface, The step of measuring the positional deviation between the front and back alignment mark formed on the main surface and the front and back alignment mark drawn on the other main surface, and the measured front and back positions And performing alignment on the basis of the positional deviation of the alignment mark for laminated, a method of aligning a photomask, which comprises a.

According to a fourth aspect of the present invention, there is provided a transparent substrate, an alignment mark for front and back alignment formed as a recess in one of the principal surfaces of the transparent substrate, and another principal surface different from the principal surface of the transparent substrate. a light shielding film formed on said light shielding, and the resist film formed on the film have a, in an effective area for exposing said main surface for forming the light shielding pattern on both surfaces of the other major surface A step of preparing a photomask blank which is a photomask blank having no light-shielding film formed on the main surface, a step of drawing front and back alignment marks together with a predetermined pattern on the other main surface, The step of measuring the positional deviation between the front and back alignment mark formed on the main surface and the front and back alignment mark drawn on the other main surface, and the measured front and back positions And performing alignment on the basis of the positional deviation of the alignment mark for laminated, a method of aligning a photomask, which comprises a.

The invention according to claim 5, a transparent substrate, have a, a reference alignment mark formed in the recess on one main surface of the transparent substrate, and the main surface in the effective area for exposure A step of preparing a photomask blank for forming a light-shielding pattern on both surfaces of the other main surface, the photomask blank having no light-shielding film formed on the main surface; and a light-shielding film on the main surface. The step of forming, the step of forming a resist film on the light-shielding film formed on the main surface, and the position when drawing on the resist film with reference to the alignment mark for reference formed on the main surface And a step of aligning the photomask.

According to a sixth aspect of the present invention, there is provided a transparent substrate, an alignment mark for front and back alignment formed as a recess in one of the principal surfaces of the transparent substrate, and another principal surface different from the principal surface of the transparent substrate. a light shielding film formed on said light shielding, and the resist film formed on the film have a, in an effective area for exposing said main surface for forming the light shielding pattern on both surfaces of the other major surface A step of preparing a photomask blank which is a photomask blank having no light-shielding film formed on the main surface, a step of drawing front and back alignment marks together with a predetermined pattern on the other main surface, Measuring the positional deviation between the front and back alignment marks formed on the main surface and the front and back alignment marks drawn on the other main surface. A method for producing a double-sided photomask.

The invention according to claim 7, a transparent substrate, have a, a reference alignment mark formed in the recess on one main surface of the transparent substrate, and the main surface in the effective area for exposure A step of preparing a photomask blank for forming a light-shielding pattern on both surfaces of the other main surface, the photomask blank having no light-shielding film formed on the main surface; and a light-shielding film on the main surface. A step of forming, a step of forming a resist film on the light shielding film formed on the main surface, a step of drawing on the resist film with reference to a reference alignment mark formed on the main surface, It is a manufacturing method of the double-sided photomask characterized by including.

According to an eighth aspect of the present invention, there is provided a transparent substrate, an alignment mark formed on one of the main surfaces of the transparent substrate, and a light shielding formed on another main surface of the transparent substrate different from the main surface. possess a membrane, and a photomask blank for forming the light-shielding pattern on both sides of the said principal surface other main surface in the effective region for exposure, the light-shielding film is formed on the main surface It is characterized by not .

The invention according to claim 9 is the photomask blank according to claim 8 , wherein the alignment mark aligns a pattern formed on the other main surface with a pattern formed on the main surface. It is characterized by being an alignment mark for front and back alignment.

The invention according to claim 10 is formed on a transparent substrate, an alignment mark for front and back alignment formed on one of the main surfaces of the transparent substrate, and another main surface different from the main surface of the transparent substrate. a light shielding film which is, the light-shielding film resist film formed on, have a photo mask for forming a light-shielding pattern on both sides of the said principal surface other main surface in the effective area for exposure Blanks, a step of preparing a photomask blank in which a light shielding film is not formed on the main surface, a step of drawing front and back alignment marks together with a predetermined pattern on the other main surface, and the main surface And a step of measuring a positional deviation between the front and back alignment mark formed on the other main surface and the front and back alignment mark drawn on the other main surface. It is a method of manufacturing a double-sided photo mask.

  According to the present invention, an alignment mark is formed in advance on one of the main surfaces with a concave portion, and by performing alignment with this alignment mark and an alignment mark drawn with a predetermined pattern on the other main surface, It becomes possible to align the front and back patterns with high accuracy.

  In addition, according to the present invention, the alignment mark formed in advance on the main surface is used as a reference alignment mark that is referred to by the electron beam drawing apparatus. Therefore, when the photomask blank is placed on the electron beam drawing apparatus, The main surface can be drawn with high accuracy regardless of the position error.

  Furthermore, since the alignment mark formed in advance on one of the main surfaces of the transparent substrate is an alignment mark formed as a recess on the surface of the transparent substrate, the light shielding film formed of a metal or a metal compound is patterned by etching. The alignment film mark can be read with high positional accuracy, and the pattern can be drawn with high positional accuracy.

1 is a perspective view of a photomask blank according to an embodiment of the present invention. It is a figure which shows the alignment mark for front and back position alignment provided in the photomask blank which concerns on embodiment of this invention. It is a figure which shows the cross section of the location in which the alignment mark for front and back position alignment provided in the photomask blank which concerns on embodiment of this invention was formed. It is a figure explaining the outline of the process of manufacturing a double-sided photomask with the photomask blank which concerns on embodiment of this invention. It is a figure which shows perspectively the photomask blank which concerns on other embodiment of this invention. It is a figure which shows the alignment mark for front and back position alignment provided in the photomask blank which concerns on other embodiment of this invention. It is a figure which shows the cross section of the location in which the alignment mark for front-and-back position alignment provided in the photomask blank which concerns on other embodiment of this invention was formed. It is a figure explaining the outline of the process of manufacturing a double-sided photomask with the photomask blank which concerns on other embodiment of this invention. It is a figure which shows an example of the front and back alignment mark position measuring apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a photomask blank according to an embodiment of the present invention, and FIG. 2 is a diagram showing alignment marks for front / back alignment provided on the photomask blank according to the embodiment of the present invention. FIG. 3 is a view showing a cross section of a portion where the alignment mark for front and back alignment provided in the photomask blank according to the embodiment of the present invention is formed. FIG. 2 is an enlarged view of the alignment mark for front / back alignment formed in an ineffective area that is not used for exposure. FIG. 3 shows a cross section of FIG. 2 taken along a plane including the line P-P 'and the line Q-Q'.

  1 to 3, 10 is a photomask blank, 100 is a transparent substrate, 110 is a first main surface 120 of the transparent substrate 100, a second main surface of the transparent substrate 100, 121 is a light shielding film layer, and 122 is a resist. A film layer 130 is a front / back alignment mark formed by a recess.

  The photomask blank 10 is used as an original plate for manufacturing a photomask used in a photolithography process in semiconductor device manufacturing or the like and a double-sided photomask, and shields light from the main surface of the transparent substrate 100 such as synthetic quartz glass. A film layer 121 is formed, and a resist film layer 122 serving as a mask material is spin-coated on the light shielding film layer 121. As the light-shielding film layer 121 formed on the transparent substrate 100, a light semi-transmission functioning as a light-shielding layer having a thickness of about 100 nm such as Cr (chromium) or a light-shielding layer such as MoSiN (molybdenum silicide nitride) having a thickness of about 80 nm. These phase shift layers are used.

  Here, the main surface of the transparent substrate 100 on the side where the light shielding film layer 121 and the resist film layer 122 are formed is defined as a second main surface 120.

  On the main surface of the photomask blank 10 where the light shielding film layer 121 and the resist film layer 122 are not provided (first main surface 110), concave and front alignment marks 130 are provided. Such concave-shaped front and back alignment marks 130 are formed by being carved into the first main surface 110 by a known method such as etching, for example, reactive ion etching. Such front and back alignment marks 130 are pattern marks other than the main pattern used when a photomask is completed as a product, and are arranged in the vicinity of the edge of the main surface of the transparent substrate 100.

  The front / back alignment mark 130 provided on the first main surface 110 is provided at a known position on the surface of the first main surface 110 and has, for example, a cross shape. In the present embodiment, the cross-shaped alignment mark 130 for front and back alignment is used, but the shape is not particularly limited, and any shape can be used as long as it can be easily observed with an optical microscope or the like. Further, there is no particular limitation on the size of the shape of the alignment mark 130 for front and back alignment and the depth when engraved as a recess, and it may be determined by the visibility with an observation device such as an optical microscope. For example, the depth of the recess of the alignment mark can be about 50 nm to 500 nm.

  In the photomask manufacturing process, the front and back alignment mark corresponding to the front and back alignment mark 130 engraved on the first main surface 110 is drawn on the second main surface 120 side. Drawing is performed simultaneously (corresponding to 126 in FIG. 4). Then, by observing the front and back alignment mark 130 on the first main surface 110 side and the front and back alignment mark on the second main surface 120 side with an optical microscope or the like, the front and back position misalignment is measured. Then, the pattern on the first main surface 110 side is drawn so as to correct this displacement. Here, the front / back alignment mark 130 is formed in advance, and the front / back alignment mark 130 and the front / back alignment mark drawn on the second main surface 120 together with the main pattern By performing the alignment with, it becomes possible to align the front and back patterns with high accuracy.

  Note that the number of front and back alignment marks 130 engraved on the first main surface 110 may be at least two (corresponding to coordinate rotation and parallel movement), but more than two may be provided. Accuracy can be improved.

  By using the alignment mark 130 of the present invention, the coordinates fixed to the transparent substrate 100 can be measured, and the positions of the drawing patterns on the first main surface and the second main surface are determined using the alignment mark 130 as a reference position. By measuring, it is possible to achieve highly accurate alignment.

  Next, a process for manufacturing a double-sided photomask using the photomask blank 10 configured as described above will be described. FIG. 4 is a diagram for explaining the outline of a process for manufacturing a double-sided photomask using the photomask blanks according to the embodiment of the present invention.

  As shown in FIG. 4A, in the process of manufacturing the double-sided photomask, the transparent substrate 100 and the front and back alignment marks 130 formed as recesses on the first main surface 110 of the transparent substrate 100 A photomask blank having a light shielding film layer 121 formed on a second main surface 120 different from the first main surface 110 of the transparent substrate 100 and a resist film layer 122 formed on the light shielding film layer 121. 10 is the starting material. Here, the resist layer 122 may be applied immediately before drawing (exposure), or may be drawn (exposure) after being stored as blanks in a state where the resist layer 122 has been applied in advance.

  FIG. 4B shows a state in which drawing of the main pattern 125 and the front / back alignment mark 126 is completed on the second main surface 120. Although steps such as exposure, development, and etching are omitted as the steps from FIG. 4A to FIG. 4B, any known steps can be used as these steps.

  Here, this pattern 125 is a pattern used when performing exposure with a double-sided photomask as a final product. Further, the front / back alignment mark 126 is drawn on the front and back of the substrate so as to be substantially coincident with the front / back alignment mark 130.

  The main pattern 125 provided on the second main surface 120 is preferably a finer pattern than the main pattern provided on the first main surface 110. This will be described with reference to FIG. FIG. 4C shows a step of inspecting the main pattern 125 provided on the second main surface 120. In the inspection of the pattern 125, in addition to the inspection from the T side where the pattern can be directly detected, the inspection from the B side through the transparent substrate 100 is also performed to inspect the fine pattern. Such precise inspection from both the T side and the B side cannot be performed in a state where the main pattern is formed on both sides. Therefore, first, the main pattern 125 provided on the second main surface 120 is assumed to be related to the fine pattern, and such an opportunity for inspection from both sides is provided.

  The next step of FIG. 4D includes a front / back alignment mark 130 formed as a recess on the first main surface 110 and a front / back alignment mark drawn and formed on the second main surface 120. 126 shows a process of measuring a positional deviation between them by observing the image 126 with an optical microscope or the like.

  As an example of a method for measuring the positional deviation between the front and back alignment marks, an alignment mark position measuring apparatus 200 having a measurement stage 230 provided with microscopes 210 and 220 for reading the positions of the front and back alignment marks as shown in FIG. Next, a calibration photomask having alignment marks whose position accuracy is known on both sides is placed on the measurement stage 230, and the position of the alignment marks on the front and back sides is read with the microscope described above, and errors associated with reading the positions on the front and back sides are detected. Calibrate. In this state, a photomask, which is an object to be measured, is placed on the measurement stage, the positions of the front and back alignment marks are read, and the positional deviation between the front and back alignment marks is measured.

  FIG. 4E shows a state in which the light shielding film layer 111 is formed on the first main surface 110 and the resist film layer 112 is further provided on the light shielding film layer 111, with the first main surface facing upward. It shows. Any known method can be used for providing the light shielding film layer 111 and the resist film layer 112. For example, the light shielding film is usually formed by sputtering, and the resist layer is applied by spin coating.

  Next, FIG. 4F is based on the positional deviation between the front and back alignment mark 130 and the front and rear alignment mark 126 by using the result of the positional deviation measured in the process of FIG. 4D. A state in which the front and back positions are aligned and the main pattern 115 is formed on the first main surface 110 is shown. Although drawing and etching processes up to FIG. 4F are omitted, any known process can be employed. Here, the main pattern 115 is preferably a coarser pattern than the pattern formed in the main pattern 125. The inspection of this pattern 115 is impossible to inspect through the transparent substrate 100 and is less accurate than the case of inspecting from both sides of the transparent substrate 100. This is because such an inspection from one side is sufficient. FIG. 4F shows a completed product of a double-sided photomask.

According to the photomask blank, the photomask alignment method, and the double-sided photomask manufacturing method of the present invention as described above, an alignment mark is formed in advance on one of the main surfaces (first main surface 110) as a recess. By aligning this alignment mark with the alignment mark drawn on the other main surface (second main surface 120) together with a predetermined pattern, the front and back patterns can be aligned with high accuracy. Is possible. Here, the main factors that determine the drawing position accuracy for drawing the main pattern 110 on the first main surface 110 with the alignment mark 130 as a reference position are the alignment mark position reading accuracy and the drawing machine repeatedly drawing the same pattern. In particular, the overlay accuracy when repeatedly drawing is dominant. Therefore, the overlay accuracy when the drawing machine repeatedly draws the same pattern is an important index indicating the limit of the pattern drawing position accuracy, but this accuracy is the maximum in the typical laser drawing machine ALTA-3000. ± 20nm, MEBES45, an electron beam drawing machine
In some models, 3σ (3 sigma) is ± 30 nm at 00, and the latest model achieves a maximum value of ± 10 nm or less, and it can be said that the drawing position accuracy is sufficient.

In the above description, the alignment mark formed in advance on one of the main surfaces of the photomask blank was formed as a recess on the substrate surface. It can be used similarly. For example, in the case of an alignment mark formed of a noble metal film or a silicon oxide film, even after the light shielding film is once formed, it can be read by removing the light shielding film in that portion by etching. Even when the alignment mark is formed using the same material as the light shielding film, a new light shielding film is formed on the surface of the transparent substrate with the alignment mark portion covered with the protective film, and the protective film is formed after the light shielding film is formed. When peeled off, the light shielding film on the protective film is also peeled off, so that the light shielding film is not formed on the alignment mark, and the position of the alignment mark can be read and used as a reference position for pattern drawing.

  Next, another embodiment of the present invention will be described. FIG. 5 is a perspective view showing a photomask blank according to another embodiment of the present invention, and FIG. 6 shows front and back alignment marks provided on the photomask blank according to another embodiment of the present invention. FIG. 7 is a diagram showing a cross section of a portion where an alignment mark for front and back alignment provided in a photomask blank according to another embodiment of the present invention is formed. FIG. 6 is an enlarged view showing front and back alignment marks formed in an ineffective area that is not used for exposure. FIG. 7 shows a cross section of FIG. 6 taken along a plane including the line P-P ′ and the line Q-Q ′.

  5 to 7, the same reference numerals as those in the previous embodiment are the same and the description thereof is omitted. This embodiment is different from the previous embodiment in that a reference alignment mark 140 that is also formed of a concave portion is provided together with an alignment mark 130 for front and back alignment formed of a concave portion on the first main surface 110. Is a point.

  Such a recessed reference alignment mark 140 can be formed by engraving the first main surface 110 by a known etching method such as reactive ion etching. Such a reference alignment mark 140 is a pattern mark other than the main pattern used when a photomask is produced as a product. Like the front and back alignment mark 130, the reference alignment mark 140 is arranged near the edge of the main surface of the transparent substrate 100. It is what is done.

  The reference alignment mark 140 provided on the first main surface 110 is provided at a known position on the surface of the first main surface 110 and has, for example, a cross beam shape. In the present embodiment, the cross-shaped reference alignment mark 140 is used, but the shape is not particularly limited, and may be a cross shape. Further, there is no particular limitation on the size of the reference alignment mark 140 and the depth when the reference alignment mark 140 is engraved as a recess. For example, the depth of the recess of the alignment mark can be about 50 nm to 500 nm.

  In the photomask manufacturing process, the front / back alignment mark (corresponding to 126 in FIG. 8) corresponding to the front / back alignment mark 130 engraved on the first main surface 110 is the second main surface 120. It is drawn on the side at the same time as this pattern is drawn. Then, by observing the front and back alignment mark 130 on the first main surface 110 side and the front and back alignment mark on the second main surface 120 side with an optical microscope or the like as described above, The displacement is measured, and the drawing on the first main surface 110 side is performed so as to correct the displacement. Here, the front / back position alignment mark 130 is formed in advance, and the front / back position alignment mark 130 and the front / back position alignment mark drawn together with the main pattern on the second main surface 120 By measuring the amount of positional deviation on the front and back and performing the alignment, the alignment of the drawing patterns on the front and back can be performed with high accuracy.

Furthermore, in the photomask manufacturing process according to the present embodiment, the reference alignment mark 140 engraved on the first main surface 110 is used to draw an electron beam when forming this pattern on the first main surface 110. An apparatus (not shown) is referred to, and the electron beam drawing apparatus performs alignment with the transparent substrate 100 with reference to the reference alignment marks 140, and patterns according to the amount of positional deviation between the front and back sides. A predetermined pattern is drawn on the resist film by correcting the drawing position. With respect to such a reference alignment mark 140, a function for performing drawing by performing alignment and position correction can be the one normally mounted in an electron beam drawing apparatus.

  As described above, since the reference alignment mark 140 formed in advance on the first main surface 110 is referred to by the electron beam drawing apparatus and the first main surface 110 is drawn, the first main surface 110 110 can be drawn with high positional accuracy.

  It is appropriate that the number of reference alignment marks 140 engraved on the first main surface 110 is the number required by the electron beam drawing apparatus.

  Next, a process for manufacturing a double-sided photomask using the photomask blank 10 configured as described above will be described. FIG. 8 is a diagram for explaining the outline of a process for manufacturing a double-sided photomask using photomask blanks according to another embodiment of the present invention.

  As shown in FIG. 8 (A), in the process of manufacturing the double-sided photomask, the alignment mark 130 for front and back alignment formed by a concave portion on the first main surface 110 of the transparent substrate 100 and the transparent substrate 110, A reference alignment mark 140, a light shielding film layer 111 formed on a second main surface 120 different from the first main surface 110 of the transparent substrate 100, and a resist film layer 112 formed on the light shielding film layer 111. The starting material is a photomask blank 10 having.

  FIG. 8B shows a state in which drawing of the main pattern 125 and the front / back alignment mark 126 is completed on the second main surface 120. Although steps such as exposure, development, and etching are omitted as the steps from FIG. 8A to FIG. 8B, well-known steps can be used as these steps.

  Here, this pattern 125 is a pattern used when performing exposure with a double-sided photomask as a final product. Further, the front / back alignment mark 126 is drawn on the front and back of the substrate so as to be substantially coincident with the front / back alignment mark 130.

  The main pattern 125 provided on the second main surface 120 is preferably a finer pattern than the main pattern provided on the first main surface 110. As shown in FIG. 8C, in the inspection of the main pattern 125 provided on the second main surface 120, in addition to the inspection from the T side, the inspection from the B side through the transparent substrate 100 is also performed. This is because a fine pattern can be inspected.

  The next step of FIG. 8D includes a front / back alignment mark 130 formed as a recess on the first main surface 110 and a front / back alignment mark drawn and formed on the second main surface 120. 126 shows a process of measuring a positional deviation between them by observing the image 126 with an optical microscope or the like. The details of this step are as already described with reference to FIG.

  Next, FIG. 8E shows a state in which a light shielding film layer 111 is formed on the first main surface 110 and a resist film layer 112 is further provided on the light shielding film layer 111. Any known method can be used for providing the light shielding film layer 111 and the resist film layer 112. Note that FIG. 8E is shown upside down with respect to FIG. 8D, with the first main surface 110 facing upward.

  In the step of FIG. 8E, based on the positional deviation between the front and back alignment mark 130 and the front and rear alignment mark 126 by using the result of the positional deviation measured in the step of FIG. 8D. Position correction is performed on the drawing pattern data to align the front and back. Such front and back alignment marks can increase the accuracy of matching the front and back patterns.

Further, in the process of FIG. 8E, the reference alignment mark 140 engraved on the first main surface 110 is referred to by an electron beam drawing apparatus (not shown), and drawing on the transparent substrate 100 is performed based on this. Position alignment is performed, and this pattern is drawn on the resist film layer 112 by an electron beam. By using the reference alignment mark 140, the accuracy of two-dimensional alignment on the first main surface 110 can be increased. As a specific example, even if position fluctuation occurs when the photomask blank is set on the drawing stage of the drawing apparatus, the position of the photomask blank is read by referring to the reference alignment mark, and pattern drawing alignment is performed. By using this, the drawing position on the photomask blank is maintained with high accuracy.

  According to the present embodiment, since the reference alignment mark 140 formed in advance on the first main surface 110 in this way is referred to by the electron beam drawing apparatus, the first main surface 110 is drawn. The first main surface 110 can be drawn with high accuracy.

  FIG. 8F shows a completed double-sided photomask in which the main pattern 110 is formed on the first main surface 110. Although drawing and etching steps up to FIG. 8F are omitted, any known steps can be adopted. Here, the main pattern 115 is preferably a coarser pattern than the pattern formed in the main pattern 125.

  According to the photomask blank, the photomask alignment method, and the double-sided photomask manufacturing method of the present invention as described above, an alignment mark is formed in advance on one of the main surfaces (first main surface 110) as a recess. By aligning the front and back alignment mark and the alignment mark drawn on the other main surface (second main surface 120) together with a predetermined pattern, the front and back alignment can be performed with high accuracy. Can be done.

  Further, according to the photomask blanks, photomask alignment method, and double-sided photomask manufacturing method of the present invention as described above, the alignment mark formed in advance on the main surface (first main surface 110) is an electron. Since it is used as the reference alignment mark 140 referred to by the line drawing apparatus, it is possible to draw the main surface (first main surface 110) with high accuracy.

  In the above description, the front and back alignment mark and the reference alignment mark are described as separate marks, but the functions may be shared by one type of mark.

DESCRIPTION OF SYMBOLS 10 ... Photomask blank 100 ... Transparent substrate 110 ... 1st main surface 111 ... Light-shielding film layer 112 ... Resist film layer 115 ... This pattern (rough pattern)
120 ... second main surface 121 ... light shielding film layer 122 ... light shielding film layer 125 ... this pattern (fine pattern)
126 ... Alignment mark 130 for front / back alignment Alignment mark 140 for front / back alignment Alignment mark 200 for reference 200 ... Front / back alignment mark position measurement device 210 ... Microscope with imaging device for alignment mark measurement (Upper side)
210 ... Microscope with imaging device for alignment mark measurement (lower side)
230 ... Measurement stage 240 ... Fixing member for microscope

Claims (10)

A transparent substrate, and an alignment mark formed in the recess on one main surface of the transparent substrate, have a, a light shielding film formed on the main surface is different from other main surface of the transparent substrate, the exposure A photomask blank for forming a light-shielding pattern on both the main surface and the other main surface in an effective region for the photomask, wherein a light-shielding film is not formed on the main surface Blanks. The alignment marks, a pattern to be formed on the other main surface, according to claim 1, wherein an alignment mark for the front and back alignment for aligning the pattern formed on the main surface Photomask blanks. The photomask blank according to claim 1 , wherein the alignment mark is a reference alignment mark that is referred to by a drawing apparatus when a pattern is drawn on the main surface. A transparent substrate, an alignment mark for front and back alignment formed as a recess in one of the main surfaces of the transparent substrate, a light shielding film formed on another main surface different from the main surface of the transparent substrate, and the light shielding have a, a resist film formed on the film, a photomask blank for forming the light-shielding pattern on both sides of the said principal surface other main surface in the effective area for exposing said main surface A step of preparing a photomask blank in which a light shielding film is not formed ,
Drawing an alignment mark for front and back alignment together with a predetermined pattern on the other main surface;
Measuring the positional deviation between the front and back alignment mark formed on the main surface and the front and back alignment mark drawn on the other main surface;
A step of performing alignment based on the measured displacement of the alignment mark for front and back alignment;
A method for aligning a photomask, comprising: A transparent substrate, have a, a reference alignment mark formed in the recess on one main surface of the transparent substrate, the light shielding on both sides of the main surface and the other main surface in the effective area for the exposure pattern A step of preparing a photomask blank in which a light shielding film is not formed on the main surface ;
Forming a light shielding film on the main surface;
Forming a resist film on the light shielding film formed on the main surface;
A method of aligning a photomask, comprising: referring to a reference alignment mark formed on the main surface and performing alignment when performing drawing on the resist film. A transparent substrate, an alignment mark for front and back alignment formed as a recess in one of the main surfaces of the transparent substrate, a light shielding film formed on another main surface different from the main surface of the transparent substrate, and the light shielding have a, a resist film formed on the film, a photomask blank for forming the light-shielding pattern on both sides of the said principal surface other main surface in the effective area for exposing said main surface A step of preparing a photomask blank in which a light shielding film is not formed ,
Drawing an alignment mark for front and back alignment together with a predetermined pattern on the other main surface;
A double-sided photomask comprising a step of measuring a misalignment between the front and back alignment mark formed on the main surface and the front and back alignment mark drawn on the other main surface. Manufacturing method. A transparent substrate, have a, a reference alignment mark formed in the recess on one main surface of the transparent substrate, the light shielding on both sides of the main surface and the other main surface in the effective area for the exposure pattern A step of preparing a photomask blank in which a light shielding film is not formed on the main surface ;
Forming a light shielding film on the main surface;
Forming a resist film on the light shielding film formed on the main surface;
And a step of drawing on the resist film with reference to a reference alignment mark formed on the main surface. A transparent substrate, and the alignment marks one on the formed main surface of the transparent substrate, the transparent substrate, have a, a light shielding film formed on the main surface is different from other major surface, for exposure A photomask blank for forming a light-shielding pattern on both the main surface and the other main surface in an effective area of the photomask blank, wherein a light-shielding film is not formed on the main surface. . The said alignment mark is an alignment mark for front-and-back positioning for aligning the pattern formed in the said other main surface, and the pattern formed in the said main surface, The alignment mark of Claim 8 characterized by the above-mentioned. Photomask blanks. A transparent substrate, an alignment mark for front and back alignment formed on one of the principal surfaces of the transparent substrate, a light shielding film formed on another principal surface different from the principal surface of the transparent substrate, and the light shielding film have a, a resist film formed, a photomask blank for forming the light-shielding pattern on both surfaces of the other major surface and the main surface in the effective area for exposure to said main surface Preparing a photomask blank in which a light-shielding film is not formed ;
Drawing an alignment mark for front and back alignment together with a predetermined pattern on the other main surface;
A double-sided photomask comprising a step of measuring a misalignment between the front and back alignment mark formed on the main surface and the front and back alignment mark drawn on the other main surface. Manufacturing method.

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