JP2000091413A - Cassette and substrate drying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the formation of stains on the element-forming surfaces of substrates. SOLUTION: A cassette has a plurality of columns, which are provided in parallel with each other in a direction intersecting substrates along the peripheral edges of the substrates as supporting beams. A cassette 20 also has side plates 26A and 26B which are provided perpendicular to columns 22 at both ends of the columns 22. The columns 22 have grooves formed at alternately repeating first intervals and second intervals, which are closer than the first intervals as substrate holding sections. As a result, when the substrates are dried, the formation of stains on the element-forming surfaces of the substrates is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette and a method for drying a substrate, and more particularly, to a cassette and a method for drying a substrate which prevent formation of a stain on an element formation surface of a substrate.

[0002]

2. Description of the Related Art In the manufacture of a liquid crystal display device, when cleaning a substrate, the substrate is housed in a cassette and sequentially immersed in a chemical solution tank, a pure water tank (hot water), and a pure water tank (normal temperature) in a batch process. After washing, Isopropyl Al
A vapor drying step of placing a cassette in an organic solvent gas atmosphere such as cohol (hereinafter referred to as IPA) and drying the substrate is performed. Hereinafter, a conventional cassette and substrate drying method will be described with reference to the drawings by way of examples.

FIGS. 4 (a) and 4 (b) are side views of a conventional cassette, respectively. FIG. 4 (a) is a side view in a direction parallel to the substrate, and FIG. 4 (b) is orthogonal to the substrate. It is a side view of a direction. The conventional cassette 10 has a plurality of substrate holding portions that hold the substrates S1 to Sn at the periphery, and the support columns 12 as a plurality of parallel support beams provided in a direction crossing the substrate along the periphery of the substrate. Have. Further, the cassette 10 includes side plates 14A and 14B provided at both ends of the column 12 so as to be orthogonal to the column. Side plate 14
Openings are formed in A and 14B (FIG. 4).
(B)).

Hereinafter, a conventional substrate drying method using the cassette 10 will be described. FIG. 5 is a flowchart showing a conventional substrate cleaning process. First, the substrates are arranged in a cassette with their element forming surfaces (hereinafter referred to as surfaces) aligned, and sequentially immersed in a chemical bath, a pure water bath (hot water), and a pure water bath (normal temperature) for cleaning. Further, the cassette 10 is carried into a drying chamber such as an IPA vapor tank in which an IPA gas atmosphere is formed, and a vapor drying step is performed. When the substrate is carried into the IPA vapor tank, the substrate is in a state of being wet with the cleaning water, and the substrate temperature is about room temperature. Since the temperature of the IPA vapor is about 82 degrees, the IPA vapor condenses on the front and back surfaces of the substrate (hereinafter, simply referred to as the substrate surface) to form droplets and fall downward by gravity. At that time, the water adhering to the substrate dissolves in the IPA droplets, and this is repeated to replace the water on the substrate surface with the IPA liquid, and thereafter the IPA liquid on the substrate surface evaporates and the substrate is dried. . The step of drying the substrate in this manner is usually completed when the temperature of the substrate reaches the temperature of the IPA vapor due to the heat of condensation of the IPA.

Here, when the normal temperature cassette enters the bath,
Since the cassette takes away the heat of the IPA vapor, the temperature in the bath temporarily drops, and the vapor line (the boundary between the IPA vapor and air) drops. The IPA solution collected at the bottom of the tank
The vaporized by heating of the heater recovers the lowered vapor line. In this process, the recovery speed of the vapor line is different between the zone inside the cassette in which the substrates are stored (between the substrates) and the zone outside the cassette. Since the zone outside the cassette has a wider zone width than the zone inside the cassette, the recovery of the vapor line is relatively quick.

[0006]

By the way, conventionally, in the vapor drying step, before the water adhering to the substrate is completely removed, the substrate is heated by radiant heat from the wall surface of the IPA vapor tank, and the substrate is heated. The attached water dries. For this reason, there is a problem that a stain (hereinafter referred to as a stain) is formed on the trace of the flow of the IPA droplet on the element formation surface of the substrate. In view of the circumstances as described above, an object of the present invention is to provide a cassette and a method for drying a substrate, which prevent the formation of spots on the element formation surface of the substrate.

[0007]

The inventors of the present invention have observed the substrate on which the stain is formed, and found that the degree of the stain varies depending on the position of the substrate in the cassette.
Table 1 shows the results of examining the relationship between the degree of water stain after the vapor drying step and the substrate position.

[Table 1] The substrates S2 and Sn in FIG. 5 are dried by heat before the water adhering to the surface is completely replaced with IPA, that is, before the water is removed, so that water stains remain.

The inventor of the present invention has intensively studied the cause and found out the following. When the side plate has an opening as described in the conventional example, the substrate S1 is largely influenced by the radiant heat from the wall surface of the IPA vapor tank, but the amount of IPA vapor condensed on the surface of the substrate is large. For this reason, no stain remains (Table 1). The substrate S2 is affected not only by the radiation heat from the wall surface of the IPA vapor tank, but also by the radiation heat from the substrate S1 due to the first drying of the substrate S1. Also, the substrate S
In No. 2, since the amount of condensation on the surface of the substrate is smaller than that of the substrate S1, the water adhering to the substrate surface is dried before the IPA is replaced with water to leave water stains. The substrate S3 and the substrate on the inner side of the cassette are less affected by the radiant heat, and the replacement of IPA from water takes a long time but is sufficiently replaced. For this reason,
No stains remain. The substrate Sn in FIG. 5 has a large amount of vapor condensation on the back surface but a small amount of condensation on the front surface because the back surface of the substrate faces the side plate 14B, and receives radiant heat from the drying chamber wall surface from the back surface side. . For this reason, the water adhering to the surface of the substrate is dried before being replaced by IPA, and water stains remain. Then, as a result of diligent studies, the present inventor has found that the zone width on the element forming surface side of the substrate is made wider than before, and has completed the present invention.

In order to achieve the above object, a cassette according to the present invention has a plurality of substrate holding portions for holding a substrate at a peripheral edge thereof, and is provided in parallel to each other and provided in a direction intersecting the substrate along the peripheral edge of the substrate. In a cassette provided with a plurality of support beams and side plates provided at both ends of the support beams at right angles to the support beams, the support beams are alternately repeated at a first interval and a first interval. It is characterized by having a substrate holding portion at a second interval shorter than the interval.

[0010] The substrate holding portion is formed of, for example, a groove.
Preferably, the first interval is in a range of 12 mm or more and 20 mm or less, and the second interval is in a range of 3 mm or more and 5 mm or less. Also preferably, the side plate is formed of a flat plate without holes, in which the size of the side plate in the direction orthogonal to the support beam is larger than the maximum plane size of the substrate. In this case, it is preferable that the side plate is made of a material having a specific heat higher to some extent, for example, a material having a higher specific heat than glass. In this case, the size and material of the side plate are usually determined so that the heat capacity is larger than a predetermined value.

[0011] A substrate drying method according to the present invention is a substrate drying method using the cassette according to the present invention, wherein the element forming surfaces of the substrate are arranged at a first interval and a surface opposite to the element forming surface is provided. The substrate is held opposite to each other at a second interval and dried. In this case,
When drying the substrate stored in the cassette, the cassette is carried into a drying chamber in an isopropyl alcohol gas atmosphere and dried.

Thus, when drying in an IPA gas atmosphere after cleaning a batch-processed glass substrate, the substrate surface can be efficiently condensed with IPA vapor and water can be removed, so that drying can be performed without causing water spots.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment the present embodiment is an embodiment of a cassette and a substrate drying method according to the present invention. FIG. 1 is a perspective view of the cassette according to the embodiment. FIGS. 2A and 2B are side views of the cassette of the present embodiment, respectively.
2A is a side view in a direction parallel to the substrate, and FIG. 2B is a side view in a direction perpendicular to the substrate. The cassette 20 of this embodiment has a plurality of support columns 22 as a plurality of parallel support beams provided in a direction intersecting the substrate along the peripheral edge of the substrate. The substrate is, for example, a glass substrate having an element formation surface on one surface. In addition, the cassette 20 includes side plates 2 provided at both ends of the column 22 at right angles to the column 22, respectively.
6A and 26B. Note that FIG. 1 illustrates a state in which the substrate is stored, and the support columns 22 are oriented vertically.

FIG. 3 is a partially enlarged side view of the column shown in FIG. The struts 22 are alternately repeated, a first interval,
And, at a second interval shorter than the first interval, a groove 28 is provided as a substrate holding portion. In the groove 28, the distance a between the ends of the groove forming the first space is 12 mm, the distance b between the ends of the groove forming the second space is 3 mm, and the groove width c is 3.5 mm. The length of the strut is 284 mm. Side plates 26A, B
Is composed of a flat plate without holes in which the size of the side plate in the direction perpendicular to the support is larger than the maximum plane size of the substrate. Side plate 26
A and B are made of a substance having a specific heat higher than that of glass, and the dimensions and materials are determined as follows so that the heat capacity is sufficiently large. That is, the side plates 26A, B
All have dimensions of 483 x 414 x 12 mm, are made of PPS (polyselinen sulfide), and have a heat capacity of 1140 kcal / ° C per side plate.

Hereinafter, a method of drying a substrate using the cassette 20 will be described. First, the substrates are stored in the cassette 20. At this time, the element holding surfaces of the substrates (surfaces) are opposed to each other with a distance of at least a distance therebetween, and the surfaces opposite to the element formation surfaces (back surfaces) are opposed to each other with a distance of at least b distance, and the substrate is held. I do. Next, the substrate is sequentially immersed in a chemical bath, a pure water bath (warm water), and a pure water bath (normal temperature) for cleaning. Furthermore,
The cassette 20 is carried into the IPA vapor tank in which the IPA gas atmosphere is formed, and a vapor drying step is performed.

In the present embodiment, the side plates 26A and 26B provided at both ends of the cassette 20 are formed of flat plates without holes in which the size of the side plate in the direction orthogonal to the support is larger than the maximum plane size of the substrate. The heat capacity of the side plates 26A and 26B is sufficiently large. Therefore, the substrate near the side plates 26A and 26B
It is not affected by radiant heat. Therefore, the amount of IPA vapor condensed on the surface of each substrate can be equalized.
Further, since the heat capacity of the side plates 26A and 26B is larger than that of the glass substrate, the radiant heat from the wall surface of the IPA vapor tank to the substrate (meaning not only the outermost substrate in the cassette but also the substrate inside the cassette). Can be completely absorbed and blocked. Further, the surface of the substrate S1 and the Sn
A large amount of IPA vapor does not condense on the back surface of the substrate. Further, the substrates are alternately arranged on the front and back sides, and the space sandwiched by the back surfaces is made as narrow as possible (3 mm), and the space sandwiched by the front surfaces (film surfaces) is made as wide as possible (12 mm). As a result, the space on the film surface side is four times wider, so that the recovery of the vapor line is faster, and the amount of IPA vapor present on the front surface side can be increased by about four times as compared with the back surface side. Therefore, the amount of condensation on the front surface can be made much larger than the amount of condensation on the back surface, and the water on the substrate surface is almost completely removed, and the formation of water spots on the surface is sufficiently prevented. You. As a result of the experiment, the occurrence rate of water stain was reduced from 15% in the past to almost 0%.

[0017]

According to the cassette according to the present invention, the support beam has the substrate holding portion at the first interval and the second interval shorter than the first interval. Further, according to the substrate drying method of the present invention, the substrate is held with the element formation surfaces of the substrate facing each other at the first interval and the surfaces opposite to the element formation surface at the second interval. And dry. This prevents the formation of stains on the element forming surface of the substrate when the substrate is dried.

[Brief description of the drawings]

FIG. 1 is a perspective view of a cassette according to a first embodiment.

FIGS. 2 (a) and 2 (b) are side views of the cassette of the present embodiment, respectively. FIG. 2 (a) is a side view in a direction parallel to the substrate, and FIG. It is a side view of the direction orthogonal to a board | substrate.

FIG. 3 is a partially enlarged side view of the column shown in FIG. 1;

4 (a) and 4 (b) are side views of a conventional cassette, respectively. FIG. 4 (a) is a side view in a direction parallel to the substrate, and FIG. 4 (b) is orthogonal to the substrate. FIG.

FIG. 5 is a flowchart showing a conventional substrate cleaning process.

[Explanation of symbols]

 Reference Signs List 10 cassette 12 support 14A, B side plate 20 cassette 22 support 26A, B side plate 28 groove

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[Procedure amendment]

[Submission date] August 23, 1999 (1999.8.2
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (8)

[Claims] A plurality of parallel support beams provided in a direction intersecting the substrate along the peripheral edge of the substrate, and a plurality of parallel support beams provided at both ends of the support beam.
A cassette provided with side plates provided orthogonally to the support beams, wherein the support beams are alternately repeated at a first interval and at a second interval shorter than the first interval. A cassette comprising: 2. The cassette according to claim 1, wherein the substrate holding portion is formed of a groove. 3. The cassette according to claim 1, wherein the first interval is in a range from 12 mm to 20 mm, and the second interval is in a range from 3 mm to 5 mm. 4. The side plate according to claim 1, wherein a size of the side plate in a direction orthogonal to the support beam is larger than a maximum plane size of the substrate. The cassette according to 1. 5. The cassette according to claim 4, wherein the side plate is made of a material having a specific heat higher than that of glass. 6. The cassette according to claim 5, wherein the size and material of the side plate are determined so that the heat capacity is larger than a predetermined value. 7. A substrate drying method using the cassette according to claim 1, wherein the element forming surfaces of the substrate are arranged at a first interval and opposite to the element forming surface. A substrate drying method, wherein the substrate is held and dried with the side surfaces facing each other at a second interval. 8. The method according to claim 7, wherein when drying the substrate stored in the cassette, the cassette is carried into a drying chamber in an isopropyl alcohol gas atmosphere and dried.
3. The method for drying a substrate according to item 1.