KR100779956B1 - Photomask blank and manufacturing process of photomask - Google Patents

Abstract

In handling blanks that require large and fine patterning, it is possible to prevent the generation of particles. In the photomask blank in which the light shielding film 2 is formed only on the part except the peripheral edge 1S on the main surface of the light transmissive substrate 1, and the peripheral portion 1S is an unfilmed region of the light shielding film 2, The translucent substrate 1 has a size of at least 300 millimeters on one side, and a width of the region S in which the film is not formed is at least 3 millimeters, and the light shielding film 2 is patterned by laser drawing. A photomask blank is provided.

Photomask Blanks, Photomasks, Patterning, Particles, Shading Films, Peripherals, Laser Drawing

Description

Photomask blank and manufacturing process of photomask

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a photomask used for transferring a pattern in photolithography technology and a photomask blank which is a raw material original thereof.

The photomask first obtains a light-transmissive substrate by precisely polishing quartz glass or the like (polishing step), and then forms a light-shielding film containing, for example, chromium as a main component on the main surface of the obtained light-transmissive substrate (film forming step), It is produced by applying a resist film on the formed light shielding film (coating step), selectively exposing the applied resist film (exposure step), developing the exposed resist film, and etching the patterned light shielding film (etching step). Here, an intermediate product of the photomask obtained through the film forming step, that is, a raw material disc, is called a photomask blank.

By the way, when it is a photomask, a photomask blank, or when carrying it between processes, since the outer periphery part and side surface part of a translucent board | substrate are gripped, it is a problem that the light shielding film formed in the part used as its holding area is easy to peel off. There is. In the case where the light shielding film is peeled off, if its peeling material adheres to the light shielding film pattern as a particle, defects such as light shielding film remain in the pattern, and in order to remove the peeling material, an increase in the number of times of cleaning of the mask or the blank is increased. can not avoid.

Then, the technique which reduces the peeling material (particle) of the light shielding film generate | occur | produced at the time of handling by preventing a light shielding film from forming in the outer peripheral part of a photomask is known (refer patent document 1, 2). These techniques can be applied to photomasks used in lithography techniques that treat silicon wafers and the like.

On the other hand, the above technique is not applied to a blank in which a fine mask pattern is formed using electron beam drawing in the exposure step. In particular, when drawing a fine pattern, an electron beam drawing is performed in the said exposure process, but in drawing a fine pattern using an electron beam, electroconductivity is performed also in the outer peripheral part of a blank in order to prevent the charge up of the board | substrate by the said electron beam. It is because it is necessary to catch (conduct pins) conduction with the light shielding film which has.

For example, in photomasks that can be used for the manufacture of display devices such as liquid crystal displays, pattern miniaturization is required in accordance with high definition of the display device. It is reality that drawing is performed.

Patent Document 1: Japanese Patent Application Laid-Open No. 60-194446 (Second Page, Fig. 1)

Patent Document 2: Japanese Patent Application Laid-Open No. 3-34050 (Section 2-3, Fig. 2)

(Initiation of invention)

However, photomasks used in the manufacture of display devices, such as liquid crystal displays, tend to be enlarged in accordance with the increase in the area of the display screen, while the pattern has become more accurate in recent years, and the larger the mask, the thicker and heavier the mask becomes. Therefore, the problem of peeling off is serious. That is, a large mask may be reliably held by using a jig that fits its outer circumference when handling this, but the heavier the mask, the greater the load on the contact portion, i.e., the outer circumference, of the jig. Of the light shielding film is easily peeled off.

In addition, by mirror-polishing not only the main surface of the substrate but also the side surfaces of the substrate, it is considered that the adhesive force of the light shielding film formed by returning to the side surface at the time of film formation is increased and the peeling of the light shielding film is reduced. Mirror polishing of the side part of a board | substrate is put to practical use. However, in a large mask such as a display device, there is an example in which the photomask of the exposure apparatus (mask aligner) is detected at the side surface, and there is a problem that the reflected light cannot be detected if the side surface of the substrate is mirror surface, When holding the side surface of the substrate with bare hands when handling the substrate, since the weight of the substrate is heavy (about 1 kg to 15 kg), there is a problem that the risk of slipping and falling if the side surface of the substrate is mirror surface increases, so that the side surface is rough. It is becoming necessary. Therefore, in a large sized photomask, the light shielding film of a side part is more likely to peel off.

As mentioned above, the problem of generation | occurrence | production of a peeling material is especially serious in the large sized blank by which the high precision pattern currently calculated | required is formed.

Therefore, an object of the present invention is to provide a technique capable of preventing generation of particles such as a peeling material in handling a blank in which a large and fine mask pattern is formed or a photomask manufactured using the same.

According to the present invention, a light shielding film is formed only on a portion of the light transmissive substrate except for the peripheral edge, and the peripheral edge portion is formed in a region where the film of the light shielding film is not formed (non-film region). A photomask blank is provided, wherein the size of the light transmissive substrate is 300 [mm] or more on one side and 3 [mm] or more in the width of the unfilmed region.

In the photomask blank of this invention, it is preferable to make the said light shielding film pattern by laser drawing.

Moreover, in the photomask blank of this invention, it is especially effective that the surface roughness Ra of the side part of the said translucent board | substrate is 0.05-0.3 micrometer rough surface.

According to the present invention, there is also provided a photomask manufactured using the photomask blank.

1 is a view schematically showing a photomask blank according to an embodiment, in which FIG. 1A is a plan view and FIG. 1B is a sectional view.

2 is an enlarged view schematically showing the periphery of the photomask blank according to the embodiment.

1: translucent substrate 1S: periphery of the translucent substrate

1T: End face of the light transmissive substrate 1C: Face picker of the light transmissive substrate

2: shading film

1 shows a photomask blank according to an embodiment. In this photomask blank, the light shielding film 2 is formed only in the part except the peripheral edge 1S on the main surface of the light transmissive substrate 1, and the peripheral part 1S becomes the unfilmed area | region of the light shielding film 2. As shown in FIG.

The transparent substrate 1 is a substrate that is substantially transparent to exposure light. The light-transmitting substrate 1 has a square or square shape in plan view, and its size is 300 [mm] or more on one side, that is, at least two opposite sides 300 out of four sides of a square or square shape. [mm] or more. On the other hand, out of four sides of each side of 300 [mm] or more, that is, square or square shape, all four sides are more effective for an even larger photomask of 300 [mm] or more. Such large photomasks are suitable for use in the manufacture of, for example, liquid crystal displays. Specifically, the size of the light transmissive substrate 1 may be 330 x 450 [mm], 390 x 610 [mm], 500 x 750 [mm], 520 x 800 [mm] or more.

Moreover, although the thickness of the translucent board | substrate 1 is not specifically limited, The board | substrate for high precision masks and the board | substrate with large size which require high flatness like the photomask of this invention tend to become thick. In one embodiment, the thickness of the light transmissive substrate 1 is 5 to 15 [mm].

The width A (see FIG. 2) of the unfilmed region 1S on the main surface of the light transmissive substrate 1 is 3 [mm] or more, preferably 5 [mm], but may be more than that. However, it is preferable that the width A of the unfilmed region 1S is a value in which the unfilmed region 1S does not overlap with the so-called drawing guarantee region of the photomask manufactured by using this blank. Specifically, in the case where the drawing assurance region is an area excluding 10 [mm] from the peripheral end surface of the translucent substrate 1, the width A of the unfilmed region 1S is preferably 10 [mm] or less.

On the other hand, in one embodiment, the width A of the unfilmed region 1S is set to 5 ± 1 [mm].

The light shielding film 2 substantially shields exposure light, and can be configured using, for example, a metal such as chromium. On the other hand, the light shielding film may have a multilayer structure or a continuous layer structure including an antireflection layer, a semi-transmissive layer, or the like, in which case the entire layer is referred to as the light shielding film 2. This light shielding film 2 is patterned using the pattern drawing by a laser drawing apparatus. That is, this photomask blank is for laser drawing.

Hereinafter, the manufacturing method of this photomask blank and the manufacturing method of the photomask using this blank are demonstrated.

[Polishing process]

First, after precisely polishing quartz glass or the like, chamfering is performed to obtain a translucent substrate 1 having a square diameter when viewed in a plane of 300 [mm] or more in width and 300 [mm] or more in length. Here, the side surface part (end surface IT and the surface picking part 1C) of the translucent board | substrate 1 does not need to be specifically ground, and may be rough. (Refer FIG. 2). Although the end surface 1T and the surface picking part 1C are rough, since the light shielding film 2 is not formed in these parts, the problem which the said light shielding film 2 peels and adheres to a mask pattern surface does not arise. Furthermore, in consideration of slippage during handling, it is preferable that the side surface, particularly the end face, of the substrate is a rough surface having a surface roughness Ra of 0.05 µm or more, more preferably 0.1 µm or more, most preferably 0.15 µm. That's it. Moreover, when the side part of a board | substrate is too rough, there also exists a problem that the particle potentially embedded in the groove will generate | occur | produce in washing | cleaning etc .. In view of this point, the surface roughness Ra of the side surface portion, particularly the end surface, of the substrate is preferably 0.3 µm or less, more preferably 0.25 µm or less, and most preferably 0.2 µm or less. In order to obtain the side surface part whose surface roughness Ra is 0.05-0.3 micrometer, it can carry out by controlling a grinding | polishing method, for example, in a diatool (a grinding wheel in the form of a wheel in which diamond grain of predetermined roughness was embedded), # It can obtain by grinding | polishing using the diamond tool of the particle size of 700- # 2400.

In addition, the width B (see FIG. 2) of the chamfer 1C can be, for example, 0.3 [mm] to 1.3 [mm].

[Film Forming Process]

Next, the light shielding film 2 is formed only in the area | region except the periphery part 1S on the main surface of the translucent board | substrate 1 obtained. The peripheral part 1S here is the area | region containing the above-mentioned end surface 1T and the surface picking part 1C.

Sputtering can be used for formation of the light shielding film 2. Sputtering may be performed in the state which supported the said translucent board | substrate 1 in the state which masked the unfilmed film | membrane area | region 1S by the frame-shaped support tool which is not shown in figure. Thereby, since the particle | grains of a spatter target do not adhere to the area | region masked by the frame-shaped support tool in the main surface of the translucent board | substrate 1, the area | region can be made into unfilmed area | region 1S. At this time, by supporting the light-transmissive substrate 1 with its film formation surface (main surface) facing downward, the problem of particles adhering to the film formation surface can be reduced.

In addition, by using an electrically conductive material as the frame-shaped supporter, the earth-ground at the time of spatter film formation in the frame-shaped supporter can be caught, and abnormal discharge can be prevented. Since the width A of the unfilmed region 1S is made 3 [mm] or more, the width | variety of the frame-shaped support opening can be made 3 [mm] or more in correspondence with this. Therefore, since sufficient earth can be secured at the time of sputtering, abnormal discharge can be reliably avoided, and as a result, the effect that a yield can be improved is acquired.

Through the above process, the photomask blank which concerns on an Example is completed.

[Application process]

Then, a resist is applied onto the formed light shielding film 2 by spin coating or the like. The resist used here is a resist for laser drawing, and specifically, NPR3510PG by Nagase Sangyo Co., etc. are mentioned.

Exposure process

Next, after apply | coating the resist film apply | coated, it selectively exposes by laser drawing. At this time, the laser drawing does not need to be performed in a vacuum like the electron beam drawing, but can be performed in the air, and thus there is an advantage that the laser drawing is completed without using a large-scale device. Moreover, as a laser drawing apparatus used here, LRS made from MICRONIC Corporation etc. are mentioned specifically ,.

[Etching process]

Next, the exposed resist film is developed to form a resist pattern, and the light shielding film 2 is etched using the resist pattern as a mask to form a light shielding film pattern. Then, the resist pattern is removed, and then a predetermined cleaning is performed to complete the photomask according to the embodiment.

According to this embodiment, the following effects can be obtained.

(1) Since the photomask blank according to the embodiment can avoid the problem of the chargeup in the conventional electron beam drawing by using it for laser drawing, the size is a large one whose one side is 300 [mm] or more. Even if the width A of the unfilmed region 1S is 3 [mm] or more, there is no problem.

(2) Since a large photomask blank or photomask (hereinafter referred to as a photomask) becomes large in weight, it must be reliably supported at the time of conveyance, so that the width of the unfilmed region 1S of the light shielding film 2 is reduced. When A is 3 [mm] or more, even if the photomask etc. are conveyed in the state which hold | maintained the end surface 1T and the surface picking parts 1C and 1C with bare hands etc., the said bare hands etc. light-shielding film 2 ) Can be reliably avoided. Therefore, the problem of peeling of the light shielding film 2 can be prevented reliably.

(3) Moreover, when conveying the said photomask etc. using the support tool which not only the end surface 1T and the surface picking parts 1C and 1C of the translucent board | substrate 1, but also the peripheral part 1S as a support area | region In addition, since the support area can be sufficiently secured to 3 [mm] or more, it is possible to stably and reliably support a large and heavy photomask while reliably preventing the problem of peeling off the light shielding film 2.

(4) As described above, by preventing peeling of the outer circumferential portion of the light shielding film 2 and removing the source of the micro foreign matters (particles), foreign matters can be prevented from adhering to the mask pattern surface such as a photomask. A defect free photomask can be produced in good yield. Therefore, the photomask and the like of the present invention have a particularly fine and strict defect inspection of the mask pattern, and a tendency of the occurrence of defects to be high due to the large mask size, for example, for TFT (thin film transistor) manufacturing. It is suitable to use as a mask of.                 

(5) In addition, since the number of times of washing such as a photomask for removing foreign matters, which has been essential in the past, can be reduced, the throughput of manufacturing such photomasks and the like can be improved.

Moreover, in the present embodiment, a rectangular one is illustrated as the light transmissive substrate 1, but the light transmissive substrate may be square.

According to the present invention, generation of particles can be prevented in handling a blank in which a large and fine pattern is required.

Claims (12)

delete delete delete delete In the manufacturing method of the photomask for manufacturing a liquid crystal display device, A light-transmissive substrate having a side of 300 mm or more, the main surface of which is precisely polished, and a light-transmissive substrate whose surface roughness is polished to a rough surface having a surface roughness of 0.05 to 0.3 µm is prepared. A photomask blank in which a light shielding film is formed is formed only in a portion except the peripheral edge on the polished translucent substrate, Applying a resist on the formed light shielding film, And selectively exposing the photomask blank to which the resist is applied by laser drawing. delete The method of claim 5, In the formation of the light shielding film, the light-transmissive substrate is supported by a conductive support, and is performed by a sputtering film. The method of claim 7, wherein A method of manufacturing a photomask, wherein the width of the non-filmed region is 3 mm or more. delete The method of claim 8, And a step of polishing the side surface of the light-transmissive substrate by means of a diaphragm, and having a roughness of 0.05 to 0.3 mu m in surface roughness. The method of claim 10, The said translucent board | substrate has the surface picking part of the width | variety of 0.3-1.3 mm, The manufacturing method of the photomask characterized by the above-mentioned. A method for manufacturing a thin film transistor, comprising using a photomask and an exposure apparatus according to any one of claims 5, 7, 8, 10, and 11.

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