JP2006208429A - Method for forming double-side mask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a double-side mask having patterns on both of top and back faces of a transparent substrate, by which layout positions of patterns on the upper face and the lower face can be superposed with high accuracy. <P>SOLUTION: The method for forming a double-side mask comprises at least steps of: forming a main pattern comprising a light shielding layer in a transfer effective region and an alignment mark out of the transfer effective region on the lower face of a transparent substrate; forming a light shielding layer in a transfer effective region on the upper face and then forming a resist layer over the entire surface; visually checking the alignment mark formed on the lower face of the transparent substrate from the upper face through the resist layer and the transparent substrate to measure the coordinates of the alignment mark; and drawing a main pattern in the resist layer on the other face (upper face) while adjusting the alignment of the main pattern using the coordinates of the alignment mark of the lower face as reference coordinates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a photomask having a pattern on both front and back surfaces (a so-called double-sided mask). Specifically, the upper surface pattern is formed by superimposing the upper surface pattern with high precision on the position of the lower surface pattern. The present invention relates to a method for making a double-sided mask that can be made.

  FIG. 4 is a side sectional view for explaining an example of the manufacturing process of the conventional double-sided mask. As shown in FIG. 4, in the process of FIG. 4A, a main pattern 45 of a light shielding metal film is formed on the lower surface of the double-sided mask. Next, in the step of FIG. 4B, the upper surface light shielding layer 43 and the upper surface resist layer 44 of the light shielding metal film layer are laminated on the upper surface. Next, in the step of FIG. 4C, an alignment mark 46 ′ is drawn on the upper resist layer 44. Next, in the step of FIG. 4D, an alignment mark of a light shielding metal film is formed on the upper surface. Next, the positions of the lower surface and upper surface patterns are measured, the accuracy of the overlapping positions of the patterns on both surfaces is calculated from the measurement results, and the amount of misalignment of the overlapping is calculated. Next, in the process of FIG. 4E, the main pattern on the upper surface is exposed and drawn. At the time of exposure drawing, alignment adjustment is performed by correcting overlapping components such as the centrality and rotation of the shift amount with reference to the coordinates of the alignment mark formed on the upper surface.

  More specifically, in order to create a double-sided mask with no overlay deviation between the lower surface and the upper surface, the centrality and rotation of the alignment mark on the upper surface and the main pattern on the lower surface are measured in advance, and the amount of overlay error is calculated from the results. Then, a double-sided mask is created by drawing the main pattern on the upper surface by correcting the misalignment in the result of alignment adjustment with the alignment mark on the upper surface (see Patent Document 1).

  However, because the main pattern on the bottom surface and the alignment mark on the top surface are measured separately and the amount of overlay deviation is calculated from the measured values, the overlay error occurs between the main pattern on the bottom surface and the main pattern on the top surface due to measurement errors. It was not possible to superimpose with high accuracy.

The known literature is described below.
JP 2004-145174 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method for producing a double-sided mask that makes it possible to superimpose an upper surface pattern and a lower surface pattern with high accuracy.

  SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and the invention according to claim 1 of the present invention provides a photomask having a pattern on both the front and back surfaces (so-called double-sided mask). The alignment mark formed on the (lower surface) is visually recognized from the other surface (upper surface) of the transparent substrate, the coordinates of the alignment mark are measured, and the coordinates of the alignment mark are used as the reference coordinates. A method for producing a double-sided mask comprising the step of adjusting the pattern alignment of the surface (upper surface) of the pattern in the step of drawing the pattern on the other surface (upper surface) of the transparent substrate.

The invention according to claim 2 of the present invention is the method for producing a double-sided mask according to claim 1, wherein the manufacturing process includes the following steps. (A) A light-shielding layer is formed on one surface (lower surface) of the transparent substrate, and a main pattern composed of the light-shielding layer within the effective transfer region and an alignment mark composed of the light-shielding layer outside the effective transfer range by lithography. Forming step.
(B) A step of forming a light shielding layer in the transfer effective arrangement region on the other surface (upper surface) of the transparent substrate.
(C) A step of forming a resist layer on the entire other surface (upper surface) of the transparent substrate.
(D) The alignment mark formed on one surface (lower surface) of the transparent substrate is visually recognized through the resist layer and the transparent substrate from the other surface (upper surface) of the transparent substrate, and the coordinates of the alignment mark are measured. A step of drawing the main pattern on the resist layer on the other surface (upper surface) by adjusting the alignment of the main pattern by using the coordinates of the alignment marks on the surface (lower surface) as reference coordinates.
(E) A step of forming a main pattern including a light shielding layer on the upper surface by forming a main pattern on the light shielding layer on the other surface (upper surface) by lithography.

The invention according to claim 3 of the present invention is the method for producing a double-sided mask according to claim 1, wherein the manufacturing process includes the following steps. (A) A light shielding layer is formed on one surface (lower surface) of the transparent substrate, and a main pattern composed of the light shielding layer within the effective transfer region and an alignment mark composed of the light shielding layer outside the effective transfer region by lithography. Forming a light shielding region provided in a region excluding a portion where the alignment mark exists.
(B) On the other surface (upper surface) of the transparent substrate, a light shielding layer is formed on the entire surface excluding a region necessary for recognizing the alignment mark formed on one surface (lower surface) from the other surface (upper surface). Process.
(C) A step of forming a resist layer on the entire other surface (upper surface) of the transparent substrate.
(D) The alignment mark formed on one surface (lower surface) of the transparent substrate is visually recognized through the resist layer and the transparent substrate from the other surface (upper surface) of the transparent substrate, and the coordinates of the alignment mark are measured. Adjusting the alignment of the main pattern by using the coordinates of the alignment marks on the surface (lower surface) as reference coordinates, and drawing the main pattern and the light shielding area on the resist layer on the other surface (upper surface).
(E) A step of forming a main pattern and a light shielding area including a light shielding layer on the upper surface by forming a main pattern and a light shielding area on the light shielding layer on the other surface (upper surface) by lithography.

  That is, according to the method for producing a double-sided mask according to the first to third aspects of the invention, in forming the pattern on the upper surface, a transparent substrate having an alignment mark formed on the lower surface is used, and the transparent substrate is formed from the upper surface. Transmits and reads the alignment mark on the lower surface, aligns it with the reading coordinate position of the alignment mark on the lower surface as a reference point, and draws the upper surface pattern with high accuracy. Can be overlapped.

  According to the method for creating a double-sided mask of the present invention, it is possible to create a double-sided mask in which the patterns of the upper and lower surfaces of the double-sided mask are superimposed on each other with high accuracy.

  FIG. 1 is a diagram showing an example of steps in a method for producing a double-sided mask according to claim 2 of the present invention.

In the step (a), the lower surface main pattern 15 is formed in the transfer effective region and the alignment mark 16 is formed outside the transfer effective region on the lower light shielding layer 12 of the transparent substrate 11. In the step (b), the upper surface light shielding layer 13 of the light shielding metal film layer is laminated and formed on the upper surface. The upper light shielding layer 13 is formed in the transfer effective area 50. By removing the alignment mark arrangement region 60 on the lower surface, the upper surface light shielding layer 13 is not formed on the upper surface of the lower alignment mark arrangement region.

  Next, in step (c), a resist is coated on the upper surface to form an upper resist layer 14.

  Next, in the step (d), the lower surface alignment mark 16 is reflected by a laser beam through a resist and a transparent substrate from a portion without the upper light shielding layer, and the image is visually recognized by a CCD camera to measure coordinates. Next, from the coordinate measurement value of the lower surface alignment mark 16, the coordinate measurement value is used as a reference point, alignment adjustment is performed, the upper surface main pattern is drawn, and the upper surface main pattern 17 'is formed. In the alignment adjustment in this process, since the coordinates of the lower surface alignment mark 16 are measured from the upper surface side, the measurement position becomes the reference point of the upper surface, and the position coordinates of the upper surface main pattern 17 are corrected with the position of the reference point as the origin. , The overlay accuracy is greatly improved.

  Finally, in step (e), development, etching, and resist layer peeling are performed to complete the double-sided mask of the present invention.

  FIG. 2 is a diagram showing an example of steps in a method for producing a double-sided mask according to claim 3 of the present invention.

  In the step (a), the light shielding area 90 is formed on the lower surface light shielding layer 22 of the transparent substrate 21 except for the lower surface main pattern 25 within the effective transfer area and the alignment mark 26 outside the effective transfer area and where the alignment mark exists. Form. In the step (b), an upper surface light shielding layer 23 of a light shielding metal film layer is laminated on the upper surface. The upper surface light shielding layer 23 is formed by masking a range necessary for recognizing the alignment mark on the lower surface from the upper surface, so that the upper surface light shielding layer is not formed on the upper surface of the alignment mark arrangement region on the lower surface.

  Next, in step (c), a resist is coated on the upper surface to form an upper surface resist layer 24.

  Next, in step (d), the alignment mark 26 on the lower surface is reflected by a laser beam through a resist and a transparent substrate from a portion without the light shielding layer on the upper surface, and the coordinates are measured by visually recognizing the image with a CCD camera. Next, from the coordinate measurement value of the lower surface alignment mark 26, the coordinate measurement value is used as a reference point, alignment adjustment is performed, the upper surface main pattern is drawn, and the upper surface main pattern 27 'is formed. In the alignment adjustment in this step, since the coordinates of the lower surface alignment mark 26 are measured from the upper surface side, the measurement position becomes the upper surface reference point, and the position coordinates of the upper surface main pattern 27 are corrected with the position of the reference point as the origin. As a result, the overlay accuracy is greatly improved.

  Finally, in step (e), development, etching, and resist layer peeling are performed to complete the double-sided mask of the present invention.

  Further, a method for visually recognizing the alignment mark formed on the lower surface of the transparent substrate in the manufacturing process according to the method for producing the double-sided mask of the present invention will be described. FIG. 3 is a diagram for explaining a method for performing alignment adjustment using the alignment mark formed on the lower surface in the present invention. That is, it is performed by visually recognizing a reflected image of the laser beam focused on the lower surface with a CCD camera.

The method of visually recognizing the image of the lower surface alignment mark 36 by laser light with a CCD camera and measuring the position is as follows:
(A) using a coordinate measuring device, irradiating a laser beam from a portion without the upper light shielding layer 33 and focusing on the lower surface of the transparent substrate 31;
(B) a step of reflecting the lower surface alignment mark 36 with laser light to visually recognize an image;
(C) A method comprising a step of measuring the image position of the lower surface alignment mark 36 using the measurement coordinate system of the apparatus and measuring the coordinates.

  A lower surface alignment mark 36 made of a light shielding layer is previously formed on the lower surface. The position of the edge of the alignment mark is measured from the contrast of the image of the CCD camera, and the deviation is calculated by comparing the design position coordinate in the design data of the lower surface alignment mark 36 with the actual measurement position of the alignment mark 36. After correcting the measurement coordinate system such as the scale, the straightness, the rotation component, and the alignment correction such as the offset to the design position coordinate, the upper surface main pattern is drawn on the upper resist layer 34, An upper surface main pattern is formed.

It is a figure which shows the manufacturing process of the double-sided mask which concerns on Claim 2 of this invention. It is a figure which shows the manufacturing process of the double-sided mask which concerns on Claim 3 of this invention. It is a figure which shows the method of visually recognizing the alignment mark formed in the lower surface of a transparent substrate in the manufacturing process of the double-sided mask of this invention. It is a figure which shows the manufacturing process of the conventional double-sided mask.

Explanation of symbols

11, 21, 31, 41 ... transparent substrates 12, 22, 32, 42 ... lower surface light shielding layers 13, 23, 33, 43 ... upper surface light shielding layers 14, 24, 34, 44 ... upper surface resist layers 15, 25, 35, 45 Lower surface main patterns 16, 26, 36 Lower surface alignment marks 46, 46 '... Upper surface alignment marks 17, 17', 27, 27 ', 47, 47' ... Upper surface main pattern 50 ... Transfer effective region 60 ... Alignment mark placement region 90: Shading area

Claims (3)

  In creating a photomask having a pattern on both front and back surfaces (so-called double-sided mask), the alignment mark formed on one surface (lower surface) of the transparent substrate is visually recognized from the other surface (upper surface) of the transparent substrate, and the alignment mark The process of adjusting the alignment of the pattern on the other surface (upper surface) of the transparent substrate is performed by measuring the coordinates of the alignment mark and using the coordinate of the alignment mark as the reference coordinate. A method for producing a double-sided mask, which is included in a drawing step. The method for producing a double-sided mask according to claim 1, wherein the manufacturing process includes the following steps.
(A) A light-shielding layer is formed on one surface (lower surface) of the transparent substrate, and a main pattern composed of the light-shielding layer within the effective transfer region and an alignment mark composed of the light-shielding layer outside the effective transfer region by lithography. Forming step.
(B) The process of forming a light shielding layer in the transfer effective area | region of the other surface (upper surface) of a transparent substrate.
(C) A step of forming a resist layer on the entire other surface (upper surface) of the transparent substrate.
(D) The alignment mark formed on one surface (lower surface) of the transparent substrate is visually recognized through the resist layer and the transparent substrate from the other surface (upper surface) of the transparent substrate, and the coordinates of the alignment mark are measured. A step of drawing the main pattern on the resist layer on the other surface (upper surface) by adjusting the alignment of the main pattern by using the coordinates of the alignment marks on the surface (lower surface) as reference coordinates.
(E) A step of forming a main pattern including a light shielding layer on the upper surface by forming a main pattern on the light shielding layer on the other surface (upper surface) by lithography. The method for producing a double-sided mask according to claim 1, wherein the manufacturing process includes the following steps.
(A) A light shielding layer is formed on one surface (lower surface) of the transparent substrate, and a main pattern composed of the light shielding layer within the effective transfer region and an alignment mark composed of the light shielding layer outside the effective transfer region by lithography. Forming a light shielding region provided in a region excluding a portion where the alignment mark exists.
(B) On the other surface (upper surface) of the transparent substrate, a light shielding layer is formed on the entire surface excluding a region necessary for recognizing the alignment mark formed on one surface (lower surface) from the other surface (upper surface). Process.
(C) A step of forming a resist layer on the entire other surface (upper surface) of the transparent substrate.
(D) The alignment mark formed on one surface (lower surface) of the transparent substrate is visually recognized through the resist layer and the transparent substrate from the other surface (upper surface) of the transparent substrate, and the coordinates of the alignment mark are measured. Adjusting the alignment of the main pattern by using the coordinates of the alignment marks on the surface (lower surface) as reference coordinates, and drawing the main pattern and the light shielding area on the resist layer on the other surface (upper surface).
(E) A step of forming a main pattern and a light shielding area including a light shielding layer on the upper surface by forming a main pattern and a light shielding area on the light shielding layer on the other surface (upper surface) by lithography.

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