JP3159658B2 - Method for etching a substrate having a transparent conductive layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma display panel (PDP) and a liquid crystal display (LCD).
Etching process used in the manufacturing process of the display device etc., and in particular etching how substrate having a transparent conductive layer.

[0002]

2. Description of the Related Art As is well known, semiconductor integrated circuits and PDPs
In addition, a plurality of etching steps and cleaning steps are required in a manufacturing process of a display device such as an LCD. These engraving processes,
For example, in the process of developing a photosensitive resin or the process of etching various thin film layers at the time of photo-etching, it is common to continuously process chemicals one by one such that a chemical solution is sprayed onto a substrate in a shower or spray. In a cleaning process in a mass production plant, a manufacturing apparatus that continuously processes pure water one by one by spraying pure water onto a substrate in a shower or spray form is often used.

FIG. 3 shows a schematic configuration diagram of such an etching apparatus. In the configuration as an etching apparatus, the reaction chamber 2, the rinsing chamber 4 and the drying chamber 5 are the minimum necessary components. A liquid drainage chamber 3 is provided between the reaction chamber 2 and the water washing chamber 4 to reduce the amount taken out to the water washing chamber 4,
Buffer chamber 1 to prevent chemical mist from scattering outside the device
Is provided on the upstream side of the reaction chamber 2. And in the specific configuration of this type of etching device,
A chemical circulation pump 6, a circulation pipe 9 system including a filter 7 for removing dust or particles in the chemical and a valve 8 for adjusting the flow rate, a nozzle 10 for injecting the chemical in the reaction chamber 2, a bottom of the reaction chamber 2 Chemical recovery pipes provided 11
And a chemical circulation tank 12 to form a closed loop
13 circulating system. Further, a supply pipe 15 system having a valve 14 for adjusting the flow rate is a chemical supply pipe for supplying the etching liquid 13 to the circulation tank 12, and although not shown, for example, a pressurized nitrogen gas is supplied from a separately installed supply tank. A new chemical solution is supplied to the circulation tank 12 by the pressure feeding by the liquid.
Similarly, a waste pipe 17 system having a valve 16 for adjusting the flow rate is a chemical liquid waste pipe for discarding the used etching liquid 13 to the outside, and not shown, but after being transferred to a separately installed waste liquid tank or the like. Procedures such as disposal as industrial waste are performed. Further, a purge gas is supplied to the etching apparatus from a dry gas supply pipe 19 having a flow rate adjusting valve 18.

Next, in the rinsing chamber 4, since pure water of appropriate purity is generally required to wash away the chemical solution adhering to the substrate, a pure water supply pipe 21 having a valve 20 for adjusting the flow rate is required.
Is provided, and a nozzle 22 for injecting pure water is disposed at a tip of the pipe. The treated water obtained by washing the substrate is passed through the drain pipe 23.In the initial stage of the pure water washing, even though the amount is small, the drainage contains a chemical solution. Discarded as factory wastewater. In addition, the washing room has a two-stage structure, and the wastewater in the first washing room is treated as described above, and the wastewater in the second washing room is recovered because of its high purity, and is again used as a pure water source for another purpose. In recent years, efforts to conserve resources, such as using it as raw water for a pure water production apparatus, have also often been adopted recently.

[0005] Further, not only pure water is simply sprayed, but also ultrasonic energy is superimposed on the pure water to be sprayed,
Alternatively, the use of a high-pressure jet to enhance the ability to remove foreign substances and particles attached to the substrate by physical force has been established in the latest cleaning machines. In the drying chamber 5, a dry gas supply pipe 26 system such as dry air or nitrogen gas having a pressure gauge 24 and a flow rate control valve 25 is provided to dry a wet substrate after washing with water. A nozzle 27 for injecting the drying gas into a sheet on the substrate is disposed. The water condensed by the nozzle 27 in the drying chamber 3 is discarded through the drain pipe 28.
The method of spraying the dried gas onto the substrate to dry it is also called an air knife. The pure water nozzle 22
It is more efficient and general that the drying nozzle 27 sprays not only from above the substrate but also from below the substrate. Reference numeral 29 in FIG. 3 is an imaginary line indicating a substrate transfer line, which is disposed for each of the substrate transfer mechanisms, an interference prevention mechanism such as a gate valve and an air curtain installed between the respective processing chambers, and each of the processing chambers. The exhaust system mechanism is also omitted in the drawing.
In addition, the drying method of the substrate other than the air knife described above,
IPA using a spin-drying method in which the substrate is rotated at a high speed to dry the substrate or a quick-drying IPA (isopropyl alcohol)
There is also a substitution type drying method, but a detailed description is omitted here.

[0006]

In [0005] Incidentally etching how substrate having a transparent conductive layer having a configuration as described above, in particular a display device such as PDP or LCD, for example the thickness 0.1 to 0.3
A transparent electrode of about μm is an essential component. But,
In the case of a transparent substrate such as a glass substrate, it is difficult to monitor or control the etching of the transparent conductive layer visually or by using optical detection means in the case of a transparent substrate such as a glass substrate because the electrode itself is transparent. It is.

Further, as a transparent conductive layer, ITO (Indium-
When Tin-Oxide is selected and hydrogen iodide (HI) water is used as an etching solution, hydrogen iodide is easily oxidized, so that iodine is liberated and dark brown to opaque. In addition, the change in the etching rate is large, and it is not easy to control the dimensional accuracy of the electrode formation of ITO.

This is partly because, in recent large display devices, the substrate size is not rarely more than 50 cm and is large because the substrate is large. From the viewpoint of safety, and as a purge gas for preventing corrosion of the etching device. And a large amount of inexpensive dry air is used as a dry gas for the air knife.
First, in the above-described single-wafer processing, the etching liquid is sprayed in the form of a shower or a spray, so that the contact area of the etching liquid with the purge gas increases by orders of magnitude as compared with a batch-type etching apparatus. In the manufacturing process of the liquid crystal display device, the above tendency was remarkable. Further, when the substrate is immersed in the etching liquid, although the generation of mist of the etching liquid is small, the area where the etching liquid comes into contact with the dry air is also significantly increased as compared with the batch type etching apparatus. Deterioration of the etching solution is inevitable.

[0009] For example, in a certain etching apparatus,
FIG. 4 (a) when the temperature was set to 40 ° C. shows data obtained by plotting the concentration of hydrogen iodide, free iodine and other components in the etching solution on the vertical axis and the number of processed substrates on the horizontal axis. FIG. It can be seen that an increase in free iodine is observed within a very short time of about 1 to 2 days on a mass production basis. As the amount of free iodine increases, the permeability of the etching solution naturally decreases. FIG. 4B shows that the permeability of the new solution (hydrogen iodide solution) is reduced by 10%.
The vertical axis represents the change in the transmittance of the etching liquid assuming 0%, and the horizontal axis represents the number of processed substrates.

[0010] The etching speed was initially 500 、 / min, but gradually increased to nearly 1000Å / min when the number of sheets exceeded 2,500. Therefore, the etching temperature was lowered or the substrate transfer speed was increased. Process conditions had to be changed. Even more inconvenient is that even when the substrate is not processed and the etching apparatus is in a standby state, the generation of free iodine is promoted by the dry air used for the purge gas as described above. In some cases, the etching conditions change regardless of the number of sheets. Thus, there is a problem that it is very difficult to control the etching speed including the fact that the etching speed is influenced by the production history of the etching device.

An object of the present invention is to solve the above-mentioned problems in the prior art, and suppresses the generation of free iodine in a hydrogen iodide solution as an etching solution to stably etch a transparent conductive layer. Of a substrate having a transparent conductive layer that can reliably achieve
An object of the present invention is to provide a time how.

[0012]

Means for Solving the Problems shower To this end, etching how substrate having a transparent conductive layer according to the present invention, the substrate while circulating hydrogen iodide solution is etching solution A reaction chamber for spraying or spraying the substrate or immersing the substrate, a cleaning chamber for cleaning the etching liquid attached to the substrate, a drying chamber for drying the substrate after cleaning, and a drying chamber for the etching liquid. An etching method in an etching apparatus provided with a means for measuring optical transmittance and a means for adding a hypophosphorous acid solution to an etching solution.

According to the present invention, an etching apparatus having the above-described structure is used, and by using such an apparatus, a hydrogen iodide solution as an etching liquid is circulated in a reaction chamber and sprayed onto a substrate in a shower or spray form. Alternatively, a step of immersing the substrate and processing, a step of cleaning the etching liquid attached to the substrate in the cleaning chamber, a step of drying the substrate in the drying chamber, and a means for measuring the optical transmittance The process of detecting the transparency of the circulating etching liquid and the etching with the transmittance of the new etching liquid as 100%.
To keep the transparency of the liquid to 80% or more, by carrying out the etching method including the step of maintaining the transparency of the etchant by means of adding appropriate hypophosphorous acid solution, free iodine in the etching solution The concentration of is measured by measuring the optical transmittance of the etching solution in the visible region, and the generation of free iodine is suppressed by appropriately replenishing a hypophosphorous acid solution (H3PO2) for preventing the oxidation of hydrogen iodide. It is possible to control the speed within an allowable range.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an apparatus for etching a transparent conductive layer according to an embodiment of the present invention. Here, components having substantially the same functions and corresponding to the components described in FIG. 3 showing the conventional example are denoted by the same reference numerals. The main difference from the conventional example of FIG. 3 is that a pressurized tank 31 for supplying the hypophosphorous acid 30 to the circulation tank 12 of the etching liquid 13, and a supply pipe 32 and a valve 33 for adjusting the flow rate, and A point where a pressurized nitrogen gas pipe 34 and a valve 35 for flow rate adjustment are added, and a part of the chemical liquid circulation pipe 9 are made of, for example, transparent vinyl chloride, PFA.
(Teflon hexafluoride resin) or a transparent member such as quartz is used to make it transparent, and the transparent part is used as a circulation tube 9 ', and a light source 36 such as a halogen lamp and a photodiode are sandwiched therebetween. The difference is that a transmittance measurement system 38 for the etching liquid 13 in which the transmitted light measuring device 37 is arranged opposite to the above is added. Needless to say, the transmittance measurement system 38 is arranged so as to cover the transparent portion of the circulation pipe 9 'or to shield the surroundings from light in order to avoid the influence of surrounding stray light.

The operation method of the present apparatus will be described below. The 60% by volume hydrogen iodide water, which is the etching liquid 13 initially supplied as a new liquid, is a highly transparent brown color. As the processing of the substrate on which the transparent conductive layer has been formed proceeds, in other words, as time progresses, it is introduced into the reaction chamber 2 for use as a purge gas, and is used in the drain chamber 3 as an air knife. Is due to the dry air flowing from the adjacent buffer chamber 1,
The hydrogen iodide solution reacts and is oxidized, and free iodine increases to darken opaquely.

In order to maintain the free iodine at a concentration that can maintain the etching rate set in advance, the optical transmittance of the etching liquid 13 is measured at an appropriate timing, and the free iodine concentration increases. If available, place hypophosphorous acid solution 30 in circulation tank 12
To convert the free iodine to hydrogen iodide again. Fig. 2 (a) shows a graph of this situation.
FIG. 2 (a) shows each component in the etching solution, and FIG. 2 (b)
Indicates the data obtained by measuring the transmittance of the etching solution. When the transmittance of the etching solution 13 (hydrogen iodide) is 100% and the transmittance of the etching solution 13 is less than 80%, an appropriate amount is shown. The hypophosphorous acid solution 30 is additionally supplied. It can be seen that the free iodine (see FIG. 2A) decreases and the transmittance (see FIG. 2B) increases each time.

This sequence control has appropriate timing,
For example, based on the output signal from the transmittance measurement system 38 every 24 hours, the valves 33 and 35 for adjusting the flow rate are opened for an appropriate time and the predetermined hypophosphorous acid solution 30 can be easily replenished to the circulation tank 12. Will be automated. In one etching apparatus, good results were obtained by setting the replenishing amount to 3 liters with respect to 100 liters of the etching liquid in the circulation tank 12.
Although it is possible to measure the transmission finer in a shorter time, if the etching rate falls within a limited range, excessive measurement such as every one hour is useless, It is more appropriate to do it at a timing of about several hours.

The volume ratio of the hypophosphorous acid solution 30 should preferably be optimized by taking into account the amount of evaporation of water in the etching solution. Even if is used, evaporation of water tends to be compensated, so that it does not become a great obstacle.

[0019]

As is apparent from the above description, according to the present invention, the method for etching a substrate having a transparent conductive layer is used while suppressing the generation of free iodine so that the etching rate is constant. You. As a result, the life of the chemical is 5 times longer than in the conventional case where the etching speed is too high and the etching liquid is replaced.
It is about twice as long, improving the operating rate as an etching device, and not only saving material, but also avoiding the situation where a large amount of free iodine is generated and adheres to the substrate and cannot be completely removed by washing. Is done. Furthermore, since the etching speed is maintained in a stable range irrespective of the number of processed substrates, the control of the etching accuracy becomes easy, and the quality assurance during continuous production becomes easy.
This provides an excellent effect that stable etching of the transparent conductive layer can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an apparatus for etching a transparent conductive layer according to an embodiment of the present invention.

FIG. 2A is a diagram showing each component in an etching solution of the etching apparatus according to the present embodiment, and FIG. 2B is a diagram showing data obtained by measuring the transmittance of the etching solution.

FIG. 3 is a schematic configuration diagram showing a conventional etching apparatus.

FIG. 4 (a) shows each component in an etching solution of a conventional etching apparatus,
(b) is a diagram showing data obtained by measuring the transmittance of the etching liquid.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Buffer room, 2 ... Reaction room, 3 ... Drain room, 4 ... Rinse room, 5 ... Drying room, 6 ... Circulation pump, 7 ... Filter, 8, 14, 16, 18, 20, 25, 33, 35 …valve,
9, 9 ': circulation piping, 10, 22: nozzle, 11: recovery piping, 12: circulation tank, 13: etching liquid (hydrogen iodide),
15, 32 ... supply pipe, 17 ... waste pipe, 19, 26 ... dry gas supply pipe, 21 ... pure water supply pipe, 23, 28 ... drain pipe,
24… Pressure gauge, 27… Drying nozzle, 29… Transport line,
30 ... hypophosphorous acid solution, 31 ... pressurized tank, 34 ... pressurized nitrogen gas piping, 36 ... light source, 37 ... transmitted light measuring instrument, 38 ... transmittance measurement system.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21 / 304,21 / 306,21 / 308 C23F 1/08

Claims (1)

(57) [Claims] 1. A process also <br/> properly morphism injection like a shower or spray-like substrate while circulating the hydrogen iodide solution is etching solution to be processed by immersing the substrate in a reaction chamber, washed Cleaning the etching solution adhering to the substrate in a chamber , and drying
Etching side of a substrate comprising the step of drying the substrate at燥室
In law, the means for measuring the light histological transmittance of fresh solution
Permeation of the etching liquid assuming that the transmittance of the etching liquid is 100%
To keep the degree over 80%, added pressure to the appropriate hypophosphite solution
It has a transparent conductive layer, wherein a step is added
Substrate etching method .