JPH0943860A - Both-side patterning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to pattern both front and rear surfaces of a transparent substrate with good accuracy. SOLUTION: A conductive film 12 is formed on the rear surface side of the transparent substrate 1 formed with a conductive film 2 and alignment markers M on the front surface side. A positive type photoresist 13 is then applied on the rear surface side of this transparent substrate 1 and is subjected to prebaking. The photoresist is thereafter subjected to exposure from the front surface side of the transparent substrate 1 and the solubilized part are washed away by development to form the alignment markers (m) on the rear surface side parts corresponding to the alignment markers M on the front surface side. Alignment is then executed on the basis of the alignment markers (m) and a mask 14 is superposed on the photoresist 13 and is developed after exposure from the rear surface side. The rear surface side is then subjected to etching and, further, the photoresist 13 is removed by ashing.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for patterning both front and back surfaces of a transparent substrate such as a glass substrate.

[0002]

2. Description of the Related Art A conventional method for patterning the surface of a transparent substrate by photolithography will be described with reference to FIG. First, as shown in FIG. 1A, a conductive film 2 to be patterned is formed on the surface of the transparent substrate 1, and a positive photoresist film 3 is formed on the surface of the conductive film 2. In addition, in the corner of the transparent substrate 1, the alignment marker M
Is formed.

Next, as shown in FIG. 1B, after the transparent substrate 1 is aligned with the alignment marker M as a reference by a microscope provided in the exposure machine, a mask 4 is overlaid on the photoresist film 3 in this state. As shown in FIG.
Exposure is performed to solubilize the part exposed to light (ultraviolet rays).

Thereafter, as shown in FIG. 3D, the exposed portion (solubilized portion) is washed away by development, etching is performed as shown in FIG. As shown in, patterning is performed by removing the photoresist film 3 by ashing.

To pattern the back surface of the transparent substrate 1, the conductive film 2 and the photoresist film 3 are formed on the back surface of the transparent substrate 1 as shown in FIG. The alignment marker M provided on the side is observed by a microscope from the back side to perform alignment, the mask 4 is overlaid on the photoresist film 3, and thereafter, the back side is also patterned by the same procedure as described above. .

[0006]

In the conventional method described above, the alignment of the back surface when patterning both surfaces of the transparent substrate is performed with reference to the alignment marker provided on the front surface. The alignment accuracy greatly depends on the perpendicularity between the optical axis of the microscope used for and the transparent substrate, and the microscope used for alignment has a shallow depth of focus, so when you look at the alignment marker on the front side from the back side, The image is blurred and accurate alignment cannot be performed.

[0007]

In order to solve the above problems, in the double-sided patterning method according to the present invention, an alignment marker formed on the front surface side of a transparent substrate such as a glass substrate is transferred to the back surface side, and this transfer is performed. The back surface is aligned using the alignment marker as a reference, and then the back surface is patterned by the photolithography method.

Here, as a specific method of transferring the alignment marker formed on the front surface side to the back surface side, for example, a positive photoresist film is formed on the back surface side, and exposure is performed from the front surface side to develop. By doing so, an alignment marker made of a positive photoresist film is formed on the back surface side.

When patterning the front surface side of the transparent substrate, alignment is performed with reference to the alignment marker on the front surface side, and when patterning the back surface side, alignment is performed with reference to the alignment marker on the back surface side. Accurate alignment is possible without being affected by the depth of focus of the alignment microscope.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
It will be described based on. In the illustrated example, the transparent substrate is already patterned on the surface side, and the positive resist is used as an example. First, FIG.
As shown in (a), the conductive film 2 and the alignment marker M are formed on the front surface side of the transparent substrate 1, and the conductive film 12 is formed on the back surface side of the transparent substrate 1.

Next, as shown in FIG. 1B, a positive photoresist 13 is applied to the back surface of the transparent substrate 1 and prebaked.

Thereafter, as shown in FIG. 1C, exposure is performed from the front side of the transparent substrate 1. Then, the exposed portion becomes solubilized, and the non-exposed portion such as the portion corresponding to the alignment marker M becomes the insolubilized portion.

Then, as shown in FIG. 3D, the portion solubilized by the development is washed away. As a result, the alignment marker m is formed on the back surface side portion corresponding to the front surface side alignment marker M.

Next, as shown in FIG. 1E, the transparent substrate 1 is turned upside down, alignment is performed with the alignment marker m as a reference, and a mask 14 is overlaid on the positive type photoresist 13 on the back surface side. After exposure from the back side as shown in FIG. 6F, development is performed as shown in FIG.

After that, as shown in FIG. 3H, the back surface side is etched with the protective film 15 formed on the front surface side in order to prevent corrosion or damage by the etching solution. The photoresist 13 is removed by ashing to obtain a device having both surfaces patterned as shown in FIG. Note that the patterning formed on both sides is symmetrical in consideration of ease of use, but the patterning is not limited to this.

[0016]

As described above, in the double-sided patterning method according to the present invention, the alignment marker formed on the front surface side of the transparent substrate such as a glass substrate is transferred to the back surface side by photolithography, Since the rear surface is aligned with the transferred alignment marker as a reference to pattern the rear surface, accurate alignment can be performed without being affected by the depth of focus of the alignment microscope. Therefore, for example, the light emitting / receiving elements can be accurately formed on both front and back surfaces of the transparent substrate, the wiring required for optical computing can be easily formed, and one-to-one imaging (not inverted) is possible. Therefore, a stereoscopic image such as an integrated photo can be easily created.

[Brief description of drawings]

1A to 1F are process diagrams of a conventional method in which patterning is performed on the front surface side of a substrate.

FIG. 2 is a diagram illustrating a conventional method for performing rear surface side alignment.

3A to 3I are process diagrams illustrating a double-sided patterning method according to the present invention.

[Explanation of symbols]

1 ... Transparent substrate, 2, 12 ... Conductive film, 3, 13 ... Photoresist, 4, 14 ... Mask, M ... Front surface side alignment marker, m ... Back surface side alignment marker.

Claims (2)

[Claims] 1. A method of patterning both front and back surfaces of a transparent substrate such as a glass substrate by photolithography, wherein an alignment marker formed on the front surface side of the transparent substrate is transferred to the back surface side, and the transferred alignment marker is transferred. The double-sided patterning method is characterized in that the rear surface is aligned on the basis of, and then the rear surface is patterned by the photolithography method. 2. The double-sided patterning method according to claim 1, wherein the alignment marker formed on the front surface side is transferred to the rear surface side by forming a positive photoresist film on the rear surface side and exposing from the front surface side. A double-sided patterning method characterized in that an alignment marker made of a positive photoresist is formed on the back surface side by performing and developing.