JPH04142029A - Processing method for fine pattern - Google Patents

Abstract

PURPOSE:To process and form a fine pattern under a condition that the occurrence probability of a pinhole and the like reduced by a method wherein a photoresist layer which is formed on a layer whose etching area is smallest is formed of a negative-type photoresist. CONSTITUTION:At least a photoresist layer 7 which is formed on a layer whose etching area is smallest out of a plurality of photoresist layers 2, 7 formed by repeating a series of processes is formed of a negative-type photoresist. At the photoresist layer 7 formed of the negative-type photoresist, an unexposed part is removed by a developing treatment. As a result, when the area of a part to be removed, i.e., a part to be processed, is very small, it is sufficient that only the part is coated with a printing-ink layer 3 which is provided with a UV shutting-off property. Consequently, a printing area can be reduced. Thereby, the occurrence probability of a defective image is reduced; it is possible to prevent a pinhole and the like from being produced in the very small part and to enhance the alignment accuracy and the dimensional accuracy of a fine pattern.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for processing fine patterns, and more specifically, for example, thin film transistors, thin film diodes, solar cells, thin film sensors, various semiconductor elements, Saw devices, TABs, etc. The present invention relates to a method for processing a fine pattern, which can efficiently form a fine pattern on a functional workpiece with high dimensional accuracy and alignment accuracy, and in mass production. Further, the fine pattern processing method of the present invention can be suitably applied to patterns used in manufacturing thermal heads, color filters, pressure sensors, etc., for example.

[Prior Art] For example, color liquid crystal displays (TPT-LCD) using thin film transistors are used in pocket TVs, portable TVs, and the like.

In recent years, 20 inch, 40 inch, 7 inch
Development of large-sized LCD flat displays such as 0-inch is active.

The second thin film transistor is usually manufactured by repeating the photolithography process about 4 to 6 times, that is, resist coating, exposure, development, and etching.

Further, for forming the fine pattern, it is also possible to use a printing method in which printing and etching of a resist pattern are repeated. When forming printed wiring or circuit patterns or forming resist patterns for etching metal plates, printing methods such as screen printing and offset printing are widely used.

[Problem to be solved by the invention] By the way, by repeating the above photolithography process, large TPT-LCs such as 40 inches and 70 inches can be manufactured.
In order to manufacture D, it is necessary to develop a dedicated device for use in the photolithography process, which requires a huge amount of cost. In particular, the development costs for large-scale exposure devices such as steppers are enormous.

On the other hand, if the above printing method is used to form fine patterns,
By repeating the printing of the resist pattern and the machining/sawching process, it is possible to relatively easily manufacture large TPT-LCDs such as 40 inches and 70 inches.

However, these printing means are suitable for forming patterns with relatively large lines (for example, 200 μm or more), and are not necessarily suitable for forming fine patterns with a line width of less than 200 μm, for example.

For example, in the screen printing method, an ink shielding mask is formed on a mesh-like screen, the non-masked part of the shielding mask is formed into a desired pattern, and the ink is allowed to pass through the non-masked part to adhere to the printing material. This is the way to do it. With this printing method, it is easy to print thick ink (generally a few μm to 20 μm thick), so it is possible to print resist patterns with excellent corrosion resistance, and since ink with low viscosity is used, pinholes are less likely to occur. Not very accurate.

However, since the practical printing width of this printing method is limited to about 200 μm, it is difficult to form fine patterns. In addition, the offset printing method uses a so-called PS plate (p++t+n5iti+e), which is a plate that has been sensitized in advance.
d) A lipophilic part and a hydrophilic part are formed in the pltte, and the hydrophilic part retains water to repel the flexible ink, thereby selectively adhering ink only to the lipophilic part, and covering the ink pattern. This is a method of printing on printed matter. In this method, in order to particularly improve printing suitability, the ink pattern on the plate is once transferred to a rubber blanket and then re-transferred to the printing material.

According to this printing method, relatively fine lines can be easily obtained. However, due to the dynamic inking method employed in this method and the two transfer operations normally performed during this method, the printed ink film thickness is only about 1 μm, resulting in a small mark! There is a drawback that pinholes and disconnections are likely to occur in the i[11 drawings. Regarding this printing method, various efforts have been made to increase the ink film thickness to form fine patterns with excellent corrosion resistance.
The limit is printing with a line width on the order of μm.

On the other hand, intaglio printing is known as a printing method that allows relatively thin lines and a large printed film thickness. In this method, for example, an image recess is formed on a copper plate, a glass plate, etc. using an engraving method or an etching method, hard ink is rubbed into the recess, and after wiping off the ink on the non-image area, the image is placed on the copper plate, etc. Print by placing the printing paper against the paper and applying strong pressure. In this intaglio printing method, by using hard ink, it is possible to print fine patterns of, for example, 10 to 90 μm.

In any case, the viscosity of the ink used in conventional printing methods such as the lithographic offset method, direct printing method, intaglio offset method, and screen printing method is very high, at 100 to 900 poise, and in particular, ink of 500 to 900 poise is used. It is said to be suitable for printing or forming fine patterns.

However, in printing using such ink, (1) the printing ink contains many impurities such as Na ions, but its high viscosity makes it impossible to purify it to remove the impurities; ■When printing on a workpiece with unevenness, the line width and film thickness may differ due to the unevenness, and it may not be possible to print on the concave areas. ■The surface condition of the workpiece or the formation on the surface There are various problems such as the transferability of the ink differs greatly depending on the type of thin film used, and (2) direct printing causes contamination of the printing surface.

The present invention has been made based on the above-mentioned circumstances, and it is possible to minimize the possibility of pinholes occurring even when the processing area is small, such as when processing contact holes, and it is possible to An object of the present invention is to provide a method that can form a fine pattern on a workpiece accurately, clearly, efficiently, and inexpensively.

[Means for Solving the Problems] The gist of the present invention for solving the above problems is to apply a photoresist layer to a workpiece in advance, and then apply a printing ink layer that blocks ultraviolet rays to the workpiece. Then, the surface on which the printing ink layer of a predetermined shape is printed is irradiated with ultraviolet rays to develop the photoresist layer, and then the workpiece is subjected to an etching process. A method of forming a fine pattern of multiple layers by repeating a series of steps of peeling off the photoresist layer, the method comprising: This method of processing a fine pattern is characterized in that the photoresist layer provided is formed of a negative type photoresist.

Hereinafter, a method for processing a fine pattern according to the present invention will be explained with reference to the drawings.

FIGS. 1(a) to 1(o) show the processing and formation process of a fine pattern by the fine pattern processing method of the present invention.

As shown in FIG. 1(a), in the fine pattern processing method of the present invention, for example, a p-8
A workpiece 1 having a conductive thin film 1b such as i (polysilicon) can be suitably used.

As shown in FIG. 1(b), in the method of the present invention, a photoresist layer 2 is first formed on the conductive thin film 1b on the workpiece 1, and then, after accurate positioning, A printing ink layer 3 is formed on the photoresist layer 2.

Here, for forming the photoresist layer 2, various positive type photoresists can be suitably used. Specifically, examples include glue casein, gum arabic,
Examples include so-called dichromate-based and carbonic acid resin-based positive photoresists containing PVA, shellac, etc. and ammonium dichromate.

The thickness of the photoresist layer 2 is usually 0.2 to 5 μm1.
Preferably it is 1 to 2 μm.

In the method of the present invention, when forming the printing ink layer 3 on the photoresist layer 2 coated on the workpiece 1,
Accurate positioning of the workpiece 1 and the printing ink layer 3 is performed.

For this positioning, for example, an alignment device shown in FIG. 2 can be suitably used.

Here, the alignment device shown in FIG. 2 is composed of a CCD camera 21, an epi-illumination device 22, a microscope 23, a CCU (electronic line generator) 24, a monitor 25, a workpiece driving jig 26, and a vacuum surface plate 27. .

That is, the CCD camera 21, the epi-illumination device 22, the microscope 23, the CCU (electronic line generator) 24, and the monitor 25 constitute an observation optical system in this alignment device, and the observation optical system has already transferred images onto the workpiece 1. It is possible to optically observe the positional relationship between the pattern of the first layer (for example, a masking layer) and the pattern of the second and subsequent layers (for example, a printing ink layer) to be newly transferred.

In this alignment device, based on the information obtained by the above-mentioned observation optical system, for example, the transfer-side register mark provided on the blanket and the workpiece (workpiece) placed on the vacuum surface plate 27 are After moving the workpiece using the workpiece driving jig 26 to a position where the register marks on the workpiece side are observed to be overlapping, the workpiece is pressed against the blanket on which the patterns of the second and subsequent layers have been transferred, and the predetermined position of the workpiece is The patterns of the second and subsequent layers are transferred to the position. Here, the blanket and the workpiece can be crimped by moving at least one of the vacuum surface plate 27 and the blanket in directions facing each other. At this time, by releasing the reduced pressure space of the vacuum surface plate 27 which is in a vacuum state to atmospheric pressure, it is possible to improve the adhesion between the blanket and the workpiece and eliminate the air remaining in the contact area between the two.

For example, the printing ink layer 3 that is formed after accurate alignment with the photoresist layer 2 on the workpiece 1 using the alignment device shown in FIG. It can be coated using suitably.

Printing ink layer 3 using ink with UV shielding properties
Once formed, a photoresist can be made into a plate by irradiating ultraviolet rays using the printing ink layer 3 as a mask.

Such inks contain, for example, one or more pigments such as finely divided carbon black, chrome yellow, silicon oxide, titanium dioxide, titanium yellow, tungsten black, cadmium red, cadmium yellow cobalt blue, and emerald green. It can be easily prepared by adding it to printing inks that do not have UV blocking properties.

The thickness of the printing ink layer 3 is usually 1 to 5 μm, preferably 1 to 2 μm.

In the method of the present invention, after forming the photoresist layer 2 and the printing ink layer 3 as described above, an exposure treatment is performed, for example by irradiation with ultraviolet rays, and then a development treatment is performed according to a conventional method.

By this development process, if the photoresist layer 2 is coated with a positive type photoresist, the first
As shown in Figure (c), the exposed portion of the photorenost layer 2 is removed, and the conductive thin film 1b provided on the workpiece 1 is partially exposed.

Then, the conductive thin film 1b is partially exposed.
For example, by performing a process such as so-called tri-etching using a mixed gas of carbon dioxide gas and oxygen gas, or a fluorocarbon gas, as shown in Fig. 1(d): The exposed portion of the conductive thin film 1b is etched.

Thereafter, the remaining photoresist layer 2 and printing ink layer 3 on the workpiece 1 are removed to form a conductive thin film 1b having a predetermined shape.

In the method of the present invention, the above steps are repeated to process and form a plurality of fine notations on the workpiece 1.

That is, as shown in FIG. 1(e), a p-3i (polysilicon) film 5 is formed on the workpiece 1 processed as described above. If the above steps are repeated, the result will be as shown in Fig.
) to FIG. 1(g) (as shown in the above gate p-8)
A fine pattern of a predetermined shape is formed by printing on the i (polysilicon) film 5.

For example, by the method of the present invention, a semiconductor substrate, TPT
When manufacturing a substrate, etc., as described above (after forming a fine pattern), perform ion doping and other treatments as shown in FIG. 1 (h). All you have to do is repeat the series of steps (1°) One of the important points in the method of the present invention is that of the plurality of photoresist layers formed by repeating the series of steps described above, at least the etching area or the minimum The purpose is to form a photoresist layer provided on a certain layer using a negative type photoresist.

In other words, when processing a minute area such as a contact hole part of a TPT substrate, for example, if a photoresist layer is formed using a positive photoresist, the area of the printing ink layer formed on this photoresist layer must also be increased. Since the value is 0, the printing area becomes large as a result.

However, when the printing area is increased, pinholes, wire breaks,
The probability of occurrence of short circuit etc. also increases.

Therefore, in the method of the present invention, the photoresist layer provided on at least the layer having the minimum etching area is formed of a negative type photoresist.

In a photoresist layer made of a negative photoresist, the unexposed portion is removed by development processing, so if the area to be removed, that is, the area to be processed, is small, only this portion has ultraviolet blocking properties. What is necessary is to apply a printing ink layer having the following properties.

The intaglio printing method can be suitably employed for transferring the printing ink layer formed on the photoresist layer using this negative type photoresist.

The shape of the printing plate used in this intaglio printing method is not particularly limited as long as it is an intaglio plate; for example, it may not only be cylindrical by wrapping the plate around a rubber roller, but also have a flat plate configuration. Also good.

There are no particular restrictions on whether pattern recesses are formed in this intaglio plate or the method of forming the pattern recesses. It may be formed by processing or etching using a mechanical application technique.

For example, the nog turn recess formed in this way,
The line width is about 3 to 70 μm, and the depth is 1 to 10 μm.
It is about m.

This printing intaglio plate is usually coated with curable ink.

Examples of the curable ink that can be used include ultraviolet curable ink, thermosetting ink, infrared curable ink,
Examples include electron beam curing ink.

In the above-mentioned intaglio printing method, a curing treatment is performed so that at least a part of the surface layer of the curable ink patterned in the notch recesses on the printing plate is in an incompletely cured state.

This curing treatment can be carried out, for example, by heating, irradiating with radiation, etc., depending on the properties of the curable ink used.

The curable ink that has been subjected to the curing treatment becomes a cured ink that has an incompletely cured surface layer portion and a completely cured portion.

That is, the ink is reactively activated by the curing process, and a thickening or curing reaction occurs within the pattern recesses, causing the ink to lose its fluidity. Note that some physical properties such as stickiness remain in the incompletely cured surface layer.

In the above-mentioned intaglio printing method, after the ink is cured irregularly as described above, a fine pattern can be printed by transferring the cured ink in the pattern recesses to a predetermined part of the workpiece. .

Here, in order to transfer the cured ink in the pattern recesses to a predetermined portion of the workpiece, the above-mentioned alignment device can be suitably used.

In addition, since the surface of the workpiece is uneven by repeating the series of steps described above, in the method of the present invention, a photoresist layer is applied in advance in order to smooth the surface of the workpiece. , transferring the cured ink onto the photoresist layer.

Therefore, the surface of the workpiece is smooth, and since the cured ink is transferred onto the photoresist layer made of organic matter, the adhesion of the cured ink is good, and impurities that may be contained in the ink are removed. It is possible to eliminate the influence.

Specifically, as shown in FIG. 1 (1), a glabellar insulating film 6 is provided on a workpiece 1 that has been subjected to ion doping treatment as necessary, and then, as shown in FIG. A negative photoresist layer 7 is formed by applying a negative photoresist onto the interlayer insulation @ 6 as shown in FIG. and then transcribe it.

In this state, if the printing ink layer 3 side is irradiated with ultraviolet rays to perform exposure and ink layer peeling development treatment, as shown in Fig. 1(k).
As shown in FIG. 3, the unexposed portions of the negative photoresist layer 7 are removed.

Next, the interlayer insulating film 6 is etched to expose a predetermined portion of the gate insulating film 4 as shown in FIG. 1(1), and then a conductive film such as an aluminum thin film is etched as shown in FIG. Then, as shown in FIG. 1(n), a positive photoresist layer 2 and a printing ink layer 3 are formed on the conductive film 8. Thereafter, if the conductive film 8 is etched using a conventional method and the photoresist layer 2 and printing ink layer 3 are peeled off, microscopic contact holes, etc., can be formed as shown in FIG. 1(o). A conductive film 8 is formed only on that portion.

As described above, the fine pattern processed and formed on the workpiece by the method of the present invention does not generate pinholes even in minute parts with a line width of about 10 μm or less, has a suitable film thickness, and has a suitable size. Accuracy and alignment accuracy are also extremely high precision.

1 Effect] In the fine pattern processing method of the present invention, the photoresist layer provided on at least the layer with the smallest etching area among the plurality of photoresist layers is formed of a negative photoresist.

Therefore, it is possible to reduce the printing area,
It is possible to reduce the probability of defective images and prevent pinholes from occurring even in minute areas.

In addition, in the method of processing a fine pattern of the present invention, a printing ink having ultraviolet blocking properties is used and the printing ink layer transferred onto the photoresist is irradiated with ultraviolet rays to expose the photoresist layer. For example, a large exposure device such as a stepper becomes unnecessary.

In addition, by aligning the workpiece with the photoresist layer and the printing ink layer on the printing plate, the alignment accuracy and dimensional accuracy of the minute turns formed on the workpiece can be dramatically improved. has improved significantly.

[Example] Next, the present invention will be described in more detail by showing examples of the present invention.

(Example 1) 1.1 mm thick AN glass [manufactured by Asahi Glass ■] substrate 1a
A p-8i (polysilicon) film was formed to a thickness of 0.1 μm to prepare a workpiece 1 having a conductive thin film 1b [first
See figure (a)].

Next, a photoresist film 2 with a thickness of 1 μm is formed on the conductive film 1111b using a bong-type photoresist [manufactured by Tokyo Ohka Co., Ltd., [0FPR-800J, viscosity 20 centipoise].
After coating, a printing ink layer 3 having a predetermined shape having ultraviolet blocking properties is coated with a film thickness of 1.5μ by the above-mentioned intaglio printing method.
The image was transferred using M [see FIG. 1(b)].

Thereafter, ultraviolet rays were irradiated from the printing ink layer 3 side using an ultra-high pressure mercury lamp, and exposure and development were performed [see FIG. 1(c)].

In this example, the ink layer was transferred using an intaglio offset method.

That is, as shown in FIG. 3(a), after applying the ink 32 to the intaglio plate 31 with a doctor 30 using a doctor blade method, the blanket 33 is applied as shown in FIG. 3(b).
The ink layer is transferred by using an intaglio offset method in which the ink from the intaglio plate 31 is transferred to the workpiece 1, and then the ink 32 transferred to the plunket 32 is transferred to the workpiece 1 as shown in FIG. I did this. In addition, in FIG. 3(b) and FIG. 3(C), 40 is a work surface plate.

In addition, a printing ink having ultraviolet blocking properties obtained by mixing carphone black into a novolak-melamine thermosetting resin was used.

Note that for the second and subsequent layers, it is necessary to accurately align the pattern with respect to the pattern shape of the first layer to print a pattern of a predetermined shape.For this purpose, for example, the alignment device shown in FIG. 2 is suitable. It can be used for.

In this example, after performing the exposure and development processing as described above, a tri-etching method using a mixed gas of carbon tetrafluoride gas and oxygen gas (CF4 gas 97%, oxygen gas 3%) was adopted. Then, the conductive thin film 1b was removed [see FIG. 1(d)].

After that, the photoresist layer 2 and the printing ink layer 3 are peeled off, and SiO2 is deposited to a thickness of 0.1 μm as the gate insulating film 4.
A gate p-8i film 5 was further formed thereon to a thickness of 0.1 μm [see FIG. 1(e)].

Next, a positive photoresist [manufactured by Tokyo Ohka Co., Ltd., rOFPR-8001, viscosity 2
0 centivoise] to a thickness of 1 μm, a photoresist layer 2 was applied, and a pattern of a predetermined shape was accurately aligned using an intaglio offset printing machine having an alignment mechanism shown in Fig. 2. A printing ink layer 3 was formed, and exposure and development were performed from the printing ink layer 3 side (see FIG. 1(f)).

Thereafter, the gate p-8i film 5 is removed by dry etching using chlorofluorocarbon gas (see FIG. 1(g)), and then the printing ink layer 3 and photoresist layer 2 are removed before ion implantation [See Figure 1 (h)]
.

Thereafter, S i 02 is formed as an interlayer insulating film 6 to a thickness of 0.
The film was formed to a thickness of 3 μm [see FIG. 1(i)].

On this interlayer insulating film 6, a negative photoresist layer 7 having a thickness of 1.5 μm was coated using a negative photoresist [manufactured by Tokyo Ohka Co., Ltd., [OMR 85, viscosity 35 centipoise].

Next, a pattern of a predetermined shape is accurately aligned using an intaglio offset printing machine having an alignment mechanism as shown in FIG. 3 was formed and printing was performed on the contact hole portion (see FIG. 1)]. At this time, since the printing area on the negative photoresist layer 7 is very small, the probability that pinholes etc. that occur during printing will appear is drastically reduced.

Thereafter, exposure and development were performed by irradiating ultraviolet rays from the printing ink layer 3 side (see FIG. 1(k)).

Next, the interlayer insulating film 6 is removed by a tri-etching method using carbon tetrafluoride gas [see W4 in FIG. 1 (1)].
], after removing the negative photoresist layer 7, a conductive film 8 made of aluminum (A1) was formed to a thickness of 0.1 μm [see FIG. 1(m)].

Thereafter, a positive photoresist layer 2 was applied to a predetermined position on the conductive film 8, and a printing ink layer 3 having a thickness of 1.5 μm was further formed on the photoresist layer 2. Next, after performing exposure and development treatment by irradiating ultraviolet rays from the printing ink layer 3 side [see FIG. 1(n)], the Bc
13+CCI By employing a dry etching method using a mixed gas to remove the conductive film 8 [Fig.
0) For reference, a thin film transistor (TPT) was fabricated.

The fine pattern processed and formed in this manner had excellent dimensional accuracy and alignment accuracy, and no pinholes, short circuits, or disconnections were observed, even in contact hole areas.

Furthermore, when the properties of the obtained TPT were measured, they were found to be equivalent to those of a TPT produced using a processing method using a normal photolithography process in which alignment exposure was performed using a stepper.

[Effects of the Invention (1) According to the present invention, a series of coating of a photoresist layer, transfer of a printing ink layer, exposure/development treatment, etching treatment, and peeling of the photoresist layer and printing ink layer are performed in this order. Among the plurality of photoresist layers formed by repeating the above process, the photoresist layer provided on at least the layer with the smallest etching area is formed using a negative photoresist, so it is possible to avoid microscopic etching, such as contact holes of TPT, etc. It is possible to provide a processing method that can process and form a fine pattern under conditions where a portion can be processed with a small printing area and the probability of occurrence of pinholes etc. is reduced.

(2) Furthermore, according to the present invention, after aligning and printing a printing ink layer that blocks ultraviolet rays in a predetermined shape on the workpiece, the surface on which the printing ink layer is printed is irradiated with ultraviolet rays to develop the phorcyst layer. Therefore, it is possible to process fine patterns efficiently and inexpensively without the need for a large exposure device such as a stepper, and it is also possible to form accurate and clear fine patterns on the workpiece using conventional printing methods. We can provide processing methods.

[Brief explanation of drawings]

1(a) to 1(0) are explanatory diagrams schematically showing the state of a workpiece when a fine pattern is processed by the method of processing a fine pattern of the present invention, and FIG. FIGS. 3(a) to 3(c) are explanatory diagrams showing an example of the configuration of an alignment device that can be suitably used in the method of the present invention. FIG. 3 is an explanatory diagram schematically showing the transfer process of FIG. 1... Workpiece, 2... Photoresist layer, 3...
・Printing ink layer, 7...Negative photoresist layer Applicant Yasuo Ishikawa)b Figure Figure

Claims (1)

[Claims] A photoresist layer is applied to the workpiece in advance, and then
A printing ink layer that blocks ultraviolet rays is aligned with the workpiece and printed on the photoresist layer, and then the surface on which the printing ink layer of a predetermined shape is printed is irradiated with ultraviolet rays to develop the photoresist layer. and then repeating a series of steps of etching the workpiece and peeling off the photoresist layer to form a fine pattern of multiple layers, the method comprising: A method for processing a fine pattern, characterized in that a photoresist layer provided on at least a layer having a minimum etching area is formed of a negative photoresist.