JP2000021809A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent etching remainder which still occurs, even if depositions have been removed by means of cleaning after an ITO(indium/tin oxide) thin film has been formed. SOLUTION: An ITO thin film 2 is formed on a quartz substrate 1 having six inch diameter, by sputtering. Depositions 3 of the ITO thin film 2 are cleaned/removed and dried at a temperature, which does not cause changes in the film quality of the ITO thin film 2. Then, resist patterns 4 are formed, the ITO thin film 2 is etched, resist is removed, and transparent conduction electrodes 21 which are pixel units are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pattern forming method.

[0002]

2. Description of the Related Art A transparent conductive substrate used for a two-dimensional matrix display such as a liquid crystal panel usually uses a transparent conductive electrode obtained by dividing a transparent conductive film into pixels. A method of forming a transparent conductive electrode is to form an indium tin oxide (hereinafter, referred to as ITO) thin film as a transparent conductive film on a transparent substrate, and then pattern the transparent conductive film by etching using a resist pattern as a mask. Has been adopted.

[0003]

However, in a liquid crystal panel or the like, as the miniaturization of a pixel unit progresses, a minute I / O generated when a transparent conductive electrode is formed is formed.
The etching residue of the TO thin film is becoming a major cause of defects such as short circuit between pixels. Usually, the ITO thin film is formed by a vacuum apparatus such as vacuum evaporation, sputtering, or chemical vapor deposition. After the film is formed, the adhered substance such as the ITO thin film adhered to the inner wall of the vacuum device is peeled off due to the contact between the substrate and the inner wall of the vacuum device accompanying the transfer of the substrate. The detached adhered substance floats when the vacuum device is opened to the atmosphere, and adheres again to the thin film-formed substrate as the adhered substance. If a resist pattern is formed in a state where the deposits are adhered, there is a problem that the resist pattern collapses, and the subsequent etching of the ITO thin film becomes an etching residue to cause a defect such as a short circuit between pixels.

[0004] The present invention provides a pattern forming method capable of preventing an etching residue.

[0005]

As a result of a detailed study of the etching residue, the inventors have found that the thin film is washed and dried after the formation of the ITO thin film, thereby removing the deposits and eliminating the collapse of the resist pattern due to the deposits. It has been found that etching residues can be reduced.

The present invention has been made based on such findings, and has the following means. The pattern forming method of the present invention includes a film forming step of forming an amorphous or polycrystalline thin film on a substrate, a cleaning step of cleaning and drying the thin film formed in the film forming step, and selecting the thin film. Patterning step of etching.

[0007] According to this configuration, it is possible to reliably remove the deposits attached to the substrate during the formation of the thin film, and to keep the film quality of the thin film formed on the substrate uniform.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking as an example the formation of a transparent conductive electrode used for a liquid crystal panel or the like.

Referring to FIG. 1, an ITO thin film 2 is formed on a 6-inch diameter quartz substrate 1 by sputtering (FIG. 1).
(A)). At this time, the deposit 3 adheres on the ITO thin film 2. Next, a stream of water is sprayed on the surface of the ITO thin film 2 to remove and remove the attached matter 3 by a scrubber washing machine to be described later to dry the moisture (hereinafter referred to as scrubber washing) (FIG. 1 (b)). Subsequently, a resist pattern 4 is formed (FIG. 1C), and the ITO thin film 2 is etched using a weakly acidic etchant containing oxalic acid as a main component (FIG. 1).
(D)), the resist is removed to form a transparent conductive electrode 21 serving as a pixel unit (FIG. 1 (e)).

FIG. 2 shows the structure of the scrubber washer. In FIG. 2, a cassette 41 a containing, for example, 25 substrates on which an ITO thin film is formed (hereinafter, referred to as an ITO substrate) 40 is installed in the loading unit 41. ITO substrate 4
The sheets 0 are sequentially transported one by one from the cassette 41a to the scrubber cleaning section 42, washed by spraying water, and dried in the drying section 43 by heating in the range of 160 ° C to 180 ° C. Continue with ITO substrate 40
Are sent to the unloading section 44 and stored in the cassette 44a, and the cleaning process by the scrubber cleaning machine is completed. In FIG. 2, the transport mechanism and the cleaning mechanism of the ITO substrate are not particularly described.

In order to examine the effect of reducing the number of deposits by cleaning, an ITO thin film was formed on the entire surface of a 6-inch diameter quartz substrate,
The number of deposits was measured before and after the scrubber washing step. The number of deposits was determined by irradiating the ITO thin film with laser light and measuring diffuse reflection. Although the number of deposits was 1109 before the scrubber cleaning, the number of deposits after the scrubber cleaning was sharply reduced to two. As a result, the pattern of the transparent conductive electrode caused by the resist pattern collapse caused by the deposits Defects and short defects could be resolved.

However, when the ITO thin film is etched on a large number of ITO substrates, the generation of etching residues other than the adhesions on some of the ITO substrates was observed, although the adhesions were reduced by scrubber cleaning. Was done. In order to investigate the cause of the etching residue due to non-adhered matter, an ITO thin film was formed on the entire surface of a quartz substrate having a diameter of 6 inches, and a scrubber cleaning was performed at a drying temperature changed from room temperature to 300 ° C. Was etched to observe the state of the etching residue. Table 1 shows the results.

[0013]

[Table 1]

As is clear from Table 1, when the drying temperature is 18
Above 0 ° C., generation of etching residues was clearly confirmed. For this reason, when the ITO thin film was etched on a large number of ITO substrates, the generation of etching residues on several ITO substrates was observed at 180 ° C. as shown in Table 1.
It is concluded that the drying process was performed at a temperature near this.

In order to investigate the cause of the generation of the etching residue, the crystallinity of indium oxide in the ITO thin film subjected to heat treatment at various temperatures after the formation of the ITO thin film was measured by X-ray diffraction. FIG. 3 shows the relationship between the result of measuring the peak height of the diffraction intensity received on the crystal lattice plane of indium oxide by irradiating the ITO thin film with characteristic X-rays and the heat treatment temperature. The ITO thin film heat-treated at 100 ° C. without heat treatment was amorphous, so that no remarkable diffraction intensity peak was observed. 20
A remarkable diffraction peak of indium oxide crystals was observed from the ITO thin film subjected to the heat treatment at 0 ° C. or higher. From the results of FIG. 3, it can be estimated that the temperature at which indium oxide in the ITO thin film changes from amorphous to crystalline is around 170 ° C. to 180 ° C. In general, indium oxide is crystallized at 130 ° C.
The temperature is said to start at a temperature exceeding 170 ° C., which confirms the change from amorphous to crystalline around 170 ° C. to 180 ° C. determined by X-ray diffraction.

From the above, the reason for the generation of etching residues other than the deposits is that if the temperature during drying of the scrubber cleaning in the cleaning step is high, a part of the amorphous ITO thin film becomes crystalline. To form an ITO thin film in which amorphous and crystalline materials are mixed, and then, when etching the ITO thin film in which amorphous and crystalline materials are mixed, the etching rate of the crystalline portion is lower than that of the amorphous portion. It is considered that the crystalline portion in the ITO thin film in which the amorphous and the crystalline are mixed remains as an etching residue.

A drying temperature of 160 ° C. is applied to many ITO substrates.
A scrubber cleaning process set as follows was performed, and the etched portion of the ITO thin film was observed. As a result, there was no etching residue and a transparent conductive electrode free from short-circuiting was formed. The sheet resistance of the ITO thin film after the formation of the transparent conductive electrode and the sheet resistance in the transparent conductive electrode substrate were the same as the values measured immediately after the formation of the ITO thin film. No washing step was found.

In this embodiment, the method of forming a pattern of an ITO thin film has been described. However, the method of forming a pattern of the present invention can be widely applied to a metal film, an insulating film, a semiconductor film, or the like without being limited by a film type. It is possible to In particular, indium oxide and tin oxide are effective as in the present embodiment, including the use as a transparent conductive electrode. In this embodiment, a quartz substrate is used as the substrate, but the present invention is not limited to this. Further, in this embodiment, the ITO thin film is formed by the sputtering method, but the present invention is not limited to this. Further, scrubber cleaning is used for cleaning, but the present invention is not limited to this, and it is sufficient that cleaning and drying are performed at a temperature that does not change the film quality of the thin film. In this embodiment, an amorphous thin film has been described. However, the present invention can also be applied to a polycrystalline thin film whose film quality changes by heating, similarly to an amorphous thin film.

[0019]

As described above, according to the pattern forming method of the present invention, a film forming step of forming an amorphous or polycrystalline thin film on a substrate, and the thin film formed in the film forming step Cleaning and drying, and a patterning step of selectively etching the thin film, it is possible to reliably remove the deposits attached to the substrate during the formation of the thin film, so that the pattern failure and short circuit failure of the thin film Can be solved. Further, according to the pattern forming method of the present invention, by setting the drying temperature of the thin film in the cleaning step to a temperature that does not change the film quality of the thin film, it is possible to prevent etching residues and the like during patterning. Quality and reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a process sectional view of a pattern forming method according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a scrubber cleaning machine in a pattern forming method according to an embodiment of the present invention.

FIG. 3 is a diagram showing the temperature dependence of the heat treatment temperature of the X-ray diffraction intensity of indium oxide in the ITO thin film used in the pattern forming method according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz substrate 2 ITO thin film 3 Deposit 4 Resist pattern 21 Transparent conductive electrode

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihide Shinsada 1-1, Komachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. F-term (reference) 4K057 WA11 WB11 WC10 WN01 4M104 AA10 BB36 DD37 DD64 DD77 GG20 HH20 5F043 AA21 BB14 DD01 GG04

Claims (6)

[Claims] A film forming step of forming an amorphous or polycrystalline thin film on a substrate; a cleaning step of cleaning and drying the thin film formed in the film forming step; and a patterning of selectively etching the thin film. And a pattern forming method. 2. The pattern forming method according to claim 1, wherein the drying temperature of the thin film in the cleaning step is set to a temperature that does not change the film quality of the thin film. 3. The pattern forming method according to claim 1, wherein a drying temperature of the thin film in the cleaning step is set in a range from room temperature to 160 ° C. 4. The pattern forming method according to claim 1, wherein the thin film is a conductive thin film. 5. The pattern forming method according to claim 4, wherein the conductive thin film is a metal oxide. 6. The pattern forming method according to claim 5, wherein the metal oxide is indium tin oxide, indium oxide or tin oxide.