JPH1012060A - Formation of transparent conductive film - Google Patents

Formation of transparent conductive film

Info

Publication number
JPH1012060A
JPH1012060A JP18422796A JP18422796A JPH1012060A JP H1012060 A JPH1012060 A JP H1012060A JP 18422796 A JP18422796 A JP 18422796A JP 18422796 A JP18422796 A JP 18422796A JP H1012060 A JPH1012060 A JP H1012060A
Authority
JP
Japan
Prior art keywords
ito film
film
transparent conductive
conductive film
resistivity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP18422796A
Other languages
Japanese (ja)
Inventor
Toshio Kudo
Shinichi Shimomaki
伸一 下牧
利雄 工藤
Original Assignee
Casio Comput Co Ltd
カシオ計算機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Casio Comput Co Ltd, カシオ計算機株式会社 filed Critical Casio Comput Co Ltd
Priority to JP18422796A priority Critical patent/JPH1012060A/en
Publication of JPH1012060A publication Critical patent/JPH1012060A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To lower the sheet resistance of an ITO film. SOLUTION: KrF excimer laser made to be thin strip-like beam with 360mm×0.1mm beam size is radiated to an ITO film 12 about 500Å thick and formed on a glass substrate 11 with 320mm×340mm plane size at 60-120mJ/cm<2> of energy deusity by scanning radiation while overlapping in the beam width direction. Consequently, the ITO film 12 is recrystallized and the sheet resistance of the recrystallized ITO film 12 becomes lower than that of the ITO film which is just formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a transparent conductive film.

[0002]

2. Description of the Related Art A transparent conductive film made of, for example, ITO (Indium Tin Oxide) is used as a transparent electrode or the like in a liquid crystal display device. By the way, some active matrix type liquid crystal display devices aim to simplify the entire manufacturing process by forming a thin film transistor as a switching element by two photolithography processes. FIGS. 6A and 6B show a part of such a conventional liquid crystal display device. This liquid crystal display device has a glass substrate 1. At each predetermined location on the upper surface of the glass substrate 1, a drain line (signal line) 2 including a drain electrode made of an ITO film, a source electrode 3, and a pixel electrode connected to the source electrode 3 are formed by a first photolithography process. 4 are formed. Glass substrate 1
A gate line (scan line) including a gate electrode made of aluminum is formed in the upper gate line (5) formation region in order from the top by the second photolithography process.
5, a gate insulating film 6 made of silicon nitride and a semiconductor thin film 7 made of polysilicon are formed.

[0003] In such a liquid crystal display device, an ITO film for forming the drain line 2 including the drain electrode, the source electrode 3 and the pixel electrode 4 is often formed by a sputtering method. The first reason is that the film formation time can be shortened. Second, the etching rate can be increased when etching the formed ITO film. Third, the resistance of the formed ITO film is small, and when the film is formed to a film thickness of about 500 °, the sheet resistance at the time of film formation is about 40Ω / □ (resistivity 2 × 10 −4 Ω · m). This is because it can be made smaller.

However, recently, in view of the increase in the area and the definition of the liquid crystal display device, further reduction in the sheet resistance of the ITO film has been desired. The reason is that when the length of the drain line 2 is increased with the increase in the area, the resistance of the drain line 2 is increased in accordance with the lengthening, and the data supplied to the pixel electrode 4 via the drain line 2 is increased. This is because a delay occurs in the signal. Further, when the width of the drain line 2 is reduced in accordance with the high definition, the resistance of the drain line 2 increases in accordance with the reduction, and the data signal supplied to the pixel electrode 4 via the drain line 2 is also increased. Is delayed. By the way, in the sputtering method, it is possible to further reduce the sheet resistance of the ITO film. As the method, first, there is a method of increasing the thickness of the ITO film, and second, there is a method of decreasing the resistivity of the ITO film by increasing the substrate temperature during film formation.

[0005]

SUMMARY OF THE INVENTION However, ITO
In the method of increasing the thickness of the film, not only the thickness of the drain line 2 is increased, but also the thickness of the pixel electrode 4 is increased, so that the transparency of the pixel electrode 4 is reduced. It takes a long time, and there is a problem that the throughput is reduced. On the other hand, in the method of lowering the resistivity of the ITO film by increasing the substrate temperature during film formation, when forming an ITO film on a glass substrate after forming a color filter in a color liquid crystal display device, a thermal filter is applied to the color filter. Limit temperature is 215 to prevent damage
Since the temperature is about ° C., there is a problem that the substrate temperature cannot be increased so much that the reduction of the resistivity of the ITO film is limited. An object of the present invention is to reduce the sheet resistance of a transparent conductive film without increasing the film thickness or increasing the substrate temperature during film formation.

[0006]

According to the present invention, a transparent conductive film formed on a substrate is irradiated with a laser to form a transparent conductive film having a lower resistivity than that at the time of film formation. is there.

According to the present invention, a transparent conductive film formed on a substrate is irradiated with a laser, whereby a transparent conductive film having a lower resistivity than that at the time of film formation can be formed.
The sheet resistance of the transparent conductive film can be reduced without increasing the film thickness or increasing the substrate temperature during film formation.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for forming an ITO film (transparent conductive film) according to an embodiment of the present invention will be described with reference to FIG.
Description will be made with reference to (A) and (B). First, FIG.
1A, an ITO film 12 is formed on the upper surface of a glass substrate 11 by a sputtering method. Next, FIG.
As shown in (B), when the ITO film 12 is irradiated with an excimer laser, the ITO film 12 is annealed and recrystallized. That is, although the ITO film 12 is in a polycrystalline state at the time of film formation, the growth of crystal grains is promoted by annealing, and the size of the crystal grains becomes large and uniform. As a result, the resistivity of the ITO film 12 becomes smaller than at the time of film formation. Therefore, the ITO film 12 can be formed without increasing the thickness of the ITO film 12 or increasing the substrate temperature during film formation.
The sheet resistance of the film 12 can be reduced.

Next, a specific example will be described. First, an ITO film having a thickness of 5 was formed on the upper surface of a glass substrate having a plane size of 320 mm × 340 mm by magnetron sputtering.
A film was formed to about 00 °. In this case, the substrate temperature was set at about 215 ° C., which is a limit temperature for preventing thermal damage to the color filters. Next, the irradiation of the excimer laser will be described. First, the beam size of the excimer laser was set to be an elongated strip of 360 mm × 0.1 mm by an optical system. The beam length is set to 360 mm so as to be longer than the length of a predetermined side of the glass substrate (320 mm in this case). As an excimer laser,
The wavelength was shorter than the fundamental absorption edge wavelength (340 nm) of the ITO film. For example, the wavelength of a KrF excimer laser is 248 nm, and the wavelength of a XeCl excimer laser is 308 nm.
In this case, a KrF excimer laser was used. The reason for using an excimer laser having a wavelength shorter than the fundamental absorption edge wavelength of the ITO film is to make the laser absorption of the ITO film as efficient as 100%.

Then, a KrF excimer laser is scanned in the beam width direction with a scanning pitch of 0.05 mm in air.
Scan irradiation was performed at 0.02 mm, 0.01 mm, and 0.005 mm (overlap ratio 50%, 80%, 90%, 95%). In this case, the energy density is 60 m
J / cm 2, 80mJ / cm 2, 100mJ / cm 2, 1
20mJ / cm 2, it was 140mJ / cm 2. However,
As shown in FIG. 2, the energy density of the KrF excimer laser has a gentle peak shape in the beam width direction in the beam width direction.
(1 mm) is defined as the half width of the beam intensity, and the beam width is multiplied by the beam length (in this case, 360 mm as described above) to obtain the beam irradiation area, and the irradiation energy of one pulse is divided by the beam irradiation area. Value.

When the dependence of the resistivity of the ITO film on the energy density was examined, the results shown in FIGS. 3 and 4 were obtained. However, FIG. 4 is an enlarged view of a part of FIG. In these figures, crosses indicate 50% overlap rate during laser scan irradiation, and squares indicate 80%.
%, ○ indicates 90%, Δ indicates 95% ITO
The average value of each resistivity of the film is shown. In FIG. 4, the dotted line indicates the resistivity of the ITO film at the time of film formation. As apparent from FIG. 3, the resistivity is in the order of 1 × 10 −4 Ω · cm in the energy density range of 60 to 100 mJ / cm 2 regardless of the overlap ratio.
When it exceeds 0 mJ / cm 2 , it rapidly increases. FIG.
As can be seen from FIG.
In the range of 100 mJ / cm 2 , the resistivity is lower than the resistivity at the time of film formation indicated by the dotted line regardless of the overlap ratio.

As is apparent from FIG. 3, a preferable energy density E is 60 mJ / cm 2 ≦ E <120 m
It can be seen that it is in the range of J / cm 2 . As described above, since the preferable energy density is relatively low, thermal damage to the color filter and the like can be prevented. Further, as is apparent from FIG. 4, the lowest resistivity is obtained when the energy density is 100 mJ / cm 2 and the overlap ratio is 90% of the mark. The resistivity in this case is 1.43 × 10 −4 Ω ·
cm, and the resistivity at the time of film formation indicated by a dotted line is 2.21 ×
It is improved by about 35% compared to about 10 −4 Ω · cm. In addition, the transparency of the ITO film has an energy density of 60 to
In the range of 140 mJ / cm 2 , it was equivalent to that at the time of film formation. Therefore, the energy density E is 60 mJ / cm 2
In the range of ≦ E <120 mJ / cm 2 , it can be said that there is no problem with the transparency of the ITO film.

Next, in order to examine the uniformity of the crystal quality of the ITO film, a KrF excimer laser was irradiated with an energy density of 10%.
50%, 80% overlap ratio at 0 mJ / cm 2 ,
Scanning irradiation was performed at 90% and 95%, and the standard deviation value (corresponding to uniformity of crystal quality) of the resistivity of the ITO film was examined. The result shown in FIG. 5 was obtained. In this figure,
The marks are 50%, 80%, 90%, and 95% overlap.
Shows the standard deviation of each resistivity of the ITO film in the case of the above, and the dotted line shows the standard deviation of the resistivity of the ITO film at the time of film formation. As is clear from FIG. 5, the standard deviation value of the resistivity is equivalent to that at the time of film formation indicated by the dotted line when the overlap ratio is 50% and 95%, and when the overlap ratio is 90%. Somewhat poor, even worse at 80% overlap. From this, the overlap ratio is 5
In the case of about 0% and about 95%, it can be said that the uniformity of the crystal quality of the ITO film is equivalent to that at the time of film formation.

In the above embodiment, the case where the ITO film is formed by the sputtering method has been described. However, the present invention is not limited to this, and the ITO film may be formed by a vapor deposition method or a coating method. When the formed ITO film is in an amorphous state, the ITO film can be polycrystallized by irradiation with an excimer laser, and the resistivity can be reduced.

[0015]

As described above, according to the present invention, a transparent conductive film formed on a substrate is irradiated with a laser to form a transparent conductive film having a lower resistivity than that at the time of film formation. Therefore, the sheet resistance of the transparent conductive film can be reduced without increasing the film thickness or increasing the substrate temperature during film formation.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views showing respective steps of forming an ITO film according to an embodiment of the present invention.

FIG. 2 is a diagram showing a beam intensity distribution in a beam width direction of an excimer laser.

FIG. 3 is a graph showing the energy density dependence of the resistivity of an ITO film.

FIG. 4 is a diagram showing details of a part of FIG. 3;

FIG. 5 is a graph showing the dependence of the standard deviation of the resistivity of the ITO film on the overlap ratio.

FIG. 6A is a plan view of a part of a conventional liquid crystal display device,
(B) is a sectional view along the line BB.

[Explanation of symbols]

 11 Glass substrate 12 ITO film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 6 Identification code Agency reference number FI Technical display location H01B 5/14 H01B 5/14 A

Claims (5)

[Claims]
1. A method for forming a transparent conductive film, wherein a transparent conductive film formed on a substrate is irradiated with a laser to form a transparent conductive film having a lower resistivity than that at the time of film formation.
2. The method according to claim 1, wherein a wavelength of the laser is shorter than a fundamental absorption edge wavelength of the transparent conductive film.
3. The method according to claim 1, wherein
The method for forming a transparent conductive film, wherein the transparent conductive film is an ITO film.
4. The method according to claim 3, wherein the IT
A method for forming a transparent conductive film, wherein the O film is formed by a sputtering method.
5. The laser according to claim 4, wherein said laser is a laser having a long and narrow beam size, and said laser has an energy density of 60 to 120 mJ / c.
A method of forming a transparent conductive film, wherein scanning irradiation is performed while overlapping in the beam width direction at about m 2 .
JP18422796A 1996-06-26 1996-06-26 Formation of transparent conductive film Pending JPH1012060A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP18422796A JPH1012060A (en) 1996-06-26 1996-06-26 Formation of transparent conductive film

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP18422796A JPH1012060A (en) 1996-06-26 1996-06-26 Formation of transparent conductive film

Publications (1)

Publication Number Publication Date
JPH1012060A true JPH1012060A (en) 1998-01-16

Family

ID=16149605

Family Applications (1)

Application Number Title Priority Date Filing Date
JP18422796A Pending JPH1012060A (en) 1996-06-26 1996-06-26 Formation of transparent conductive film

Country Status (1)

Country Link
JP (1) JPH1012060A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001056088A1 (en) * 2000-01-28 2001-08-02 Japan Science And Technology Corporation Light emitting diode and semiconductor laser
WO2007125860A1 (en) * 2006-04-24 2007-11-08 Showa Denko K.K. Method for manufacturing gallium nitride compound semiconductor light emitting element, gallium nitride compound semiconductor light emitting element and lamp
US7342637B2 (en) 2002-03-29 2008-03-11 Lg.Philips Lcd Co., Ltd. Liquid crystal display device and method for manufacturing the same
JP2009277640A (en) * 2007-10-10 2009-11-26 Asahi Kasei Corp Forming method for transparent conductive film

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001056088A1 (en) * 2000-01-28 2001-08-02 Japan Science And Technology Corporation Light emitting diode and semiconductor laser
US7342637B2 (en) 2002-03-29 2008-03-11 Lg.Philips Lcd Co., Ltd. Liquid crystal display device and method for manufacturing the same
WO2007125860A1 (en) * 2006-04-24 2007-11-08 Showa Denko K.K. Method for manufacturing gallium nitride compound semiconductor light emitting element, gallium nitride compound semiconductor light emitting element and lamp
JP2007294578A (en) * 2006-04-24 2007-11-08 Showa Denko Kk Gallium nitride compound semiconductor light emitting device, method for manufacturing the same, and lamp
US8207003B2 (en) 2006-04-24 2012-06-26 Showa Denko K.K. Method of manufacturing gallium nitride-based compound semiconductor light-emitting device, gallium nitride-based compound semiconductor light-emitting device, and lamp
JP2009277640A (en) * 2007-10-10 2009-11-26 Asahi Kasei Corp Forming method for transparent conductive film

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