JPH01179465A - Formation of thin film - Google Patents

Abstract

PURPOSE:To ensure that there will be no residue remaining in the vicinity of open grooves in a region worked on in a patterning process by a method wherein the open grooves are provided, patterning is accomplishd for the formation of a conductive film or laminate, and then an acid is applied to melt away the patterning-produced residue if any. CONSTITUTION:A layer is built of silicon oxide or the like to serve as a blocking layer between a substrate and a thin film to be worked on. On them, zinc oxide or the like or their laminate is deposited, and then a metal conductive film for example of molybdenum is formed. The conductive film is exposed to a laser beam not more than 400mums in wavelength, when the blocking layer is also affected and removed, which results in opening grooves 6-1-6-n. In this process, for the prevention of impurities from oozing out of the substrate- constituting material, a second blocking layer 8 is formed on the entirety, which is done after the removal of residue 5-1 by using an acid. In this design, alkaline ions are prevented from oozing out because the blocking layer 8 is relatively thick in the open grooves.

Description

[Detailed Description of the Invention] ``Industrial Field of Application'' The present invention is applicable to the patterning process of thin films used in solar cells, liquid crystal display devices, etc. using inexpensive soda glass, without using a photoresist. Direct drawing (pattern formation) is performed to form open grooves using a laser beam. The present invention also relates to a method for selectively processing a thin film in which the build-up of the residue at the open groove portion is removed by dissolving the residue generated due to this direct writing.

``Prior art 1'' A method is known in which a photoresist is used when patterning a thin film. This method has the characteristic that it is possible to pattern a conductive film such as a transparent conductive film on top of the blocking layer without damaging the blocking layer.However, this method coats a photoresist in a predetermined shape, and It involves a complicated process of using a mask, patterning, and then removing the photoresist.Therefore, there is a need for an inexpensive patterning method.

As an inexpensive method, direct drawing (
(pattern formation) is known.

This laser processing method uses a YAG laser (wavelength 1.
06 μm) is generally considered to be effective. In this method using infrared rays, the optical energy of the laser beam is only 1.23 eV (1.06 μm).

On the other hand, a workpiece formed on a glass substrate, such as a transparent conductive film (hereinafter referred to as CTF), has an optical energy band width of 3 to 4 eV. For this reason, tin oxide, indium oxide (including ITO).

CTFs such as zinc oxide (ZnO) do not have sufficient light absorption properties for YAG laser light, and the energy of the laser light is not used effectively. In addition, in the laser processing method using the Q-switch oscillation of the YAG laser, the pulsed light has an average of 0.5 to
mm, pulse frequency 3K if z, pulse width 60n
If the scanning speed is 30 to 6 seconds), the strong light energy is
It must be added and processed at a rate of 0 cm/min.

As a result, the CTF can be processed using this laser beam, but at the same time, it causes microcracks to a depth of 10 to 50 μm and damages the soda glass with the blocking layer provided below. Ta.

In addition, as irradiation light other than the YAG laser, 400n
We irradiate a pulsed laser with a wavelength of ultraviolet light of less than m (energy: 3.1 eV or more) to create a beam spot with a width of 2 to 200 μm (for example, 1 (bz
m), irradiating a linear pattern with a length of 10 to 60 cm, for example 30 cm, with one or several pulses at the same location,
A method of patterning a thin film by forming linear grooves is known. By linearly irradiating this pulsed light with a wavelength of 400 nm or less (pulse width is extremely short, 5 to 30 ns), the absorption efficiency of light energy in transparent materials such as CTF can be evaluated using a YAG laser (1.06 μm). 1 in case
As a result, the processing speed can be increased by more than 10 times.

In this case, an excimer laser beam is used as the initial light source for boat fishing. Therefore, the initial light irradiation surface has a rectangular shape, and the intensity is approximately uniform within the irradiation surface. For this purpose, a so-called beam expander that expands the width of the light is used to enlarge the area into a rectangular shape. Thereafter, the laser beam is focused into a slit shape along one of the X or Y directions using a cylindrical rod lens, that is, a cylindrical lens.

Thus 2~200I! For example, create a linear groove with a width of 10 μm.

These methods using laser light do not use any photoresist, so they are characterized in that the manufacturing process is easy. However, the open grooves formed by laser beam machining have the disadvantage that a large amount of machining residues, ie, residues, tend to remain in the grooves.

Due to this laser processing, residues from the processed portion also remain on the conductive film in the non-processed area, forming convex portions. Since the mixture and compound of soda glass and the conductive film remaining in the grooves of the processed part have some conductivity, it is not possible to sufficiently insulate the conductive gaps between adjacent patterned conductors.

In addition, the height of the swelling caused by this mixture is 0.5 to 1
There was also μm.

When solar cells, liquid crystal display devices, and other electronic components are manufactured using a substrate in such a state, short circuits between electrodes, disconnections, uneven coloring, etc. may occur due to the unevenness, resulting in a decrease in the manufacturing yield of electronic components. I was imitating it.

Object of the Invention The present invention provides a thin film on a glass substrate, particularly a glass substrate, on which a buffer layer having flatness, that is, a blocking layer against impurities such as alkali ions, is provided using a laser beam having a wavelength of 400 μm or less. The target material is a laminate, especially a laminate with a conductive film such as a transparent conductive film or a metal film, an insulating film such as a color filter underneath, and a non-single-crystal semiconductor, etc. The purpose of this invention is to realize a good processed surface without any residue near the grooves of the processed part when laser processing and patterning a conductive film or a laminate.

"Structure of the Invention j In order to achieve the above object, a blocking layer (such as silicon oxide) doped with sufficiently low amounts of phosphorus, sodium, and boron is formed between the base substrate such as soda glass and the thin film that is the workpiece. A thin film, particularly ITO, tin oxide, zinc oxide, or a laminate thereof, and a metal conductive film such as chromium or molybdenum are further laminated on this as a first blocking layer. It may also be a laminate with an insulator or semiconductor provided on the top surface.Then, by irradiating this conductive film with a laser beam having a wavelength of 400 μm or less, the blocking layer is simultaneously irradiated and removed in addition to the conductive film. As a result, part of the mixture causes a bulge due to workpiece residue at the end of the machined groove, and
This promotes leaching of impurities such as sodium from the substrate material.

Therefore, these residues are treated with acids (hydrofluoric acid diluted with water,
After selectively eluting the residue with a fluoride mixed solution such as acidic ammonium fluoride (acid capable of eluting the residue), a second blocking layer is formed over the entire structure. This second blocking layer uses a liquid material, which is applied, printed or coated, and the whole is heated and cured. Then, since the groove formed by the laser processing part constitutes a recessed part, this part can be relatively thicker than that on the thin film. and preferably 50 to 300 people thick on the thin film,
For example, when there are 200 people, the thickness is 100 to 600 people (50 people on the thin film corresponds to 100 people, 300 people corresponds to 600 people), for example, 400 people and 30% or more thickness. can be made. This thickness makes it possible to prevent alkaline ions such as sodium in the substrate from seeping out to the outside.

Furthermore, after forming a laminate with other semiconductors, insulators, etc. that have been previously made on or below this conductive film, all of these are patterned with laser light, and the upper surface of the laminate thus formed is It is also possible to fill and form the second blocking layer on the side surfaces and the open groove. At this time, the thickness of the stack becomes thicker, so the open grooves are formed thicker than the second blocking layer on the stack, making the shielding effect of impurity ions such as sodium more significant. can do.

Examples are shown below.

"Example 1" FIG. 2 shows a system diagram of laser processing of the present invention using an excimer laser. The excimer laser (
14) (wavelength 248 nm, Eg = 5.0 eV) was used. This laser, as shown in FIG. 3(8), has an initial light beam (21) of 16 mm x 20 mm and an efficiency of 3z, thus having 350 mJ (millijoules). Furthermore, this beam is connected to a beam expander (15)
The long area ratio or area was increased. That is, 16mm
It was enlarged to 300 mm (Fig. 3 (22)), and an energy density of 5.6 x 10-2 mJ/mm was obtained at this time.

Next, slits with a spacing of 2mm x 300mm (
16) Pass the laser beam through the 2 mm x 30
Obtain a laser beam (23) of 0 mm. (Figure 3 (C)
) Furthermore, a synthetic quartz cylindrical lens (17) is used to condense the light (24
) did. (Fig. 3 (D)) Although the width of the slit used at this time is not particularly determined, it is necessary to narrow down the laser beam to such an extent that the spherical aberration of the cylindrical lens does not affect it. Further, the time during groove opening of the workpiece can be arbitrarily selected depending on the performance of the cylindrical lens.

In FIG. 1, a plurality of open grooves (6-1, 6-2, 6-3, . . . n) are formed by irradiating a slit-shaped pulsed light onto a substrate. That is, as shown in FIG. 1(A),
A substrate is used which has a blocking layer (2) (100 to 1500 nm thick), for example silicon oxide, 200 nm thick on soda glass (also called soda lime glass). Furthermore, a conductive film (4) such as indium tin oxide or chromium is formed thereon to a thickness of 1000 to 3000 nm.

As shown in FIG. 1(B), laser beams are applied to these as shown in FIG.
Irradiation was performed using the optical system shown in Figure 3.

The pulsed light was 248 nm light from a KrF excimer laser. This is because the optical energy band width of that light is 5. This is because since the voltage is OeV, the workpiece absorbs enough light and only the conductive film can be selectively processed.

Pulse width 2 On seconds, repetition frequency 1-100Hz.

For example, light irradiation was performed at 10 Hz.

Then, open grooves (6-1), (6-2), (6-3
) to obtain...

At this time, there is a residue (5-1) inside the open groove and a convex portion (5-2) on the patterned conductive film (4).

These are eluted with diluted hydrofluoric acid (1/10 diluted with water), and then sufficiently ultrasonic cleaning is performed with acetone and pure water.

Then, as shown in Figure 1 (C), the lecture (6-1), (6
-2) and (6-3) had only grooves and were able to remove all the residue.

However, in this groove, the blocking layer (2) is also removed at the same time, and the upper part of the soda glass substrate is also partially removed (
It has been gouged out (to a depth of 0.3 to 1 μm) and exposed. Therefore, if a liquid crystal display device or the like is made using only the structure shown in Figure 1 (C), this substrate material will come into direct contact with the liquid crystal that requires ultra-high purity, and sodium will be present in the liquid crystal during long-term use. There is a risk that it may ooze out.

Also, if used as is for image sensors, solar cells, etc.
Sodium oozes into the amorphous semiconductor from this portion, causing photodegradation effects and promoting N-type conversion of the semiconductor.

For this reason, in the present invention, the upper surfaces of these are shown in FIG.
A second blocking layer was formed as shown in D).

This blocking layer is preferably made of an organic resin that blocks sodium such as polyimide, or an inorganic material such as silicon oxide. These materials have a liquid state (in a non-polymerized state or a liquid state of an organic silicide such as silazane) in their raw material state, and the raw materials are spread over the conductive film to a thickness of 50 to 2,500 layers, for example, 300 layers on a conductive film. Coat the groove to a thickness of about 500 coats. This application coating may be performed using a spinner, or may be performed using a printing method, a coater method, or a spray method.

Then, since these have surfaces coated with liquid, they form the recesses (6-1), (6-2)...
-Can be applied in larger amounts and formed thicker.

Furthermore, these liquid raw materials were thermally cured.

For example, a polyimide solution is heated and baked at 230° C. for 12 hours. Even in the method using a liquid organosilicon compound, it was oxidized by heating in air or oxygen to transform it into a blocking layer of solid silicon oxide.

In this way, as shown in FIG. 1(D), the solvent evaporated and the volume contracted and became dense due to the heating reaction, making it possible to completely prevent alkali ions and the like from seeping out to the outside. The seepage of organic matter into the conductive film from below was blocked by the blocking layer (2) (first blocking layer). And the conductive film or laminate from the side periphery and top surface (
7) Impurities seep into the second blocking layer (
8) blocked the intrusion.

Furthermore, in a liquid crystal display device, it is effective for the second blocking layer to function as an alignment film by rubbing the surface thereof as necessary.

Ideally, this second blocking layer should fill all of the recesses so that its top surface roughly coincides with the top surface of the conductive film, and prevent local electric field concentration at the ends of the conductive film. It will be done. For this reason, it is more preferable to apply and form a liquid raw material and then harden it.

In particular, the width of the groove is 20μm, 10μm, 5μm than 50μm.
In order to not only make it as small as 3 μm but also to make the inside of the groove thicker, it is preferable to apply a liquid raw material that can use surface tension and to harden it.

Thus, for example, the substrates shown in the vertical cross-sectional view shown in FIG. I was able to make a display device.

In this case, the second blocking layer was made of silicon oxide on one substrate side, and the second blocking layer was made of polyimide organic resin on the other substrate side. Then, the organic resin side was subjected to rubbing treatment. As a result, even when this alignment film was subjected to high-temperature treatment at 50° C. for 1000 hours, the contrast of the display area was 20, and no deterioration was observed in this value.

In FIG. 1(D), the IT separated by this groove
When a 50V DC voltage was applied between O(4-1) and (4-2) and the current flowing between ITO was measured at 100 locations, all of them were 1 to 2 Xl0-9A (length 30cm, width 10μm opening) Since the second blocking layer also prevents surface leakage, the obtained values were constant values and did not cause any practical problems.

? Effect J According to the present invention, since the conductive film and the entire outer periphery of the laminate are covered with a blocking layer during laser processing, leakage between adjacent conductors can be further reduced.

According to the present invention, a good machined surface was obtained without generating residues remaining around the machined grooves that existed in the conventional method.

As a result, there is no short circuit or disconnection between electrodes, and ITO
We were able to provide sufficient insulation between the two.

In the present invention, the conductive film is ITO, SiO□+ZnO
Alternatively, a multilayer film of these and metals such as chromium and molybdenum may be used.

It is also effective to stack an insulating film having a color filter function above or below these conductive films so that the conductive films have the same shape.

Furthermore, it is effective to stack a non-single crystal semiconductor on top of this conductive film, and then configure another conductive film thereon for use in an image sensor.

The present invention aims at high reliability by providing a second blocking layer covering all of these laminates, and was able to obtain high reliability even using an inexpensive soda glass substrate. .

In the present invention, the case where the width between the open grooves (the area left unprocessed) is large is described. However, by connecting the light irradiations next to each other, for example, the remaining area can be reduced to 20 μm,
It is also possible to set the removed portion to 400 μm.

[Brief explanation of the drawing]

FIG. 1 shows a method for manufacturing a substrate having a conductive film according to the present invention. FIG. 2 shows an outline of the laser processing system used in the present invention. FIG. 3 shows the beam shape of laser light.

Claims (1)

[Claims] 1. A glass substrate comprising a glass substrate, a blocking layer, and a conductive film or a laminate, the conductive film or laminate and the blocking layer being removed by irradiating a laser beam to form an open groove. A method for forming a thin film, comprising the steps of patterning the conductive film or the laminate, and, after the step, dissolving the residue produced by the laser beam irradiation with acid. 2. A thin film forming method according to claim 1, wherein the acid is a fluoride solution, and the residue is silicon oxide, or a mixture or compound of silicon oxide and a conductive film. 3. The thin film forming method according to claim 1, wherein the conductive film is made of a light-transmitting conductive film or a metal film.