JP2007530311A - Two-layer transparent conductor scheme with improved etching characteristics for transparent electrodes in electro-optic displays - Google Patents

Abstract

A two-layer transparent conductor scheme suitable for producing transparent electrodes in flat panel displays (LDC, ELD, plasma displays, LEDs, OLEDs), touch panels, optical filters, solar cells and other applications is presented. Top layer typically made of indium tin oxide, thinner lower layer doped zinc oxide _Al 2 _{O 3} (AZO), or doped ZnO with gallium oxide (GZO), or _Al 2 _{O 3} and Ga _It consists of ZnO (AGZO) doped with both ₂ O ₃ . The lower layer has a significantly higher wet chemical etch rate than the upper layer, thereby allowing faster and more uniform etching of the upper ITO layer, thus preventing the formation of ITO “islands”.

Description

  The present invention relates to layered solid systems, in particular transparent conductive films, flat panel displays such as LCDs, PDPs, ELs, LEDs, FEDs and OLEDs, especially in electro-optic displays as these transparent electrode layers. As well as the production and structuring of said system.

The problems to be solved and the prior art layered solid systems, in particular in the form of thin films on substrates, are well known and have been applied for various purposes such as optical coatings, interference filters, surface treatments, especially transparent Conductive films (TCF) are used, for example, as electrodes for electro-optic displays and as materials for touch-sensitive input devices such as touch screens. Obviously, some of these systems must be constructed in a manner that only partially covers their substrates in order to achieve the desired functionality of the devices in which they are used.

  TCF has been heavily studied in industry for many years (eg “Semiconducting Transparent Thin Films”, HL Hartnagel et al., Institute of Physics Publishing, Bristol and Philadelphia, ISBN 0 7503 0322 0, p.1 ff reference). Most TCFs have been coated by some thin film processing on transparent substrates such as glass. These TCF films are etched to form conductive electrodes to produce electronic devices, particularly electro-optic displays. Unlike silicon-based semiconductor integrated circuits, TCF circuits are much more suitable for many electro-optic applications because they allow light transmission.

  Transparent electronic devices are available in current technologies such as liquid crystal display (LCD), plasma display panel (PDP), light emitting diode (LED), organic light emitting diode (OLED), electroluminescence (EL), field emission display (FED). Have already been widely applied to touch panels, solar cells, waveguide switches, optical filters, transparent EMI shields and many other applications. Their basic property requirements include high transmittance, low specific resistance, good environmental stability and etchability. Moreover, the TCF film should also be chemically resistant to several alkaline solutions, high humidity and high temperature to meet the complex processing flow requirements for these electronic devices at each factory. . For example, indium tin oxide (ITO) has excellent light transmission in the visible region of the electromagnetic spectrum, good specific resistance, high hardness, and good environmental stability. This has therefore become the most widely used material for all TCFs.

However, most TCFs are n-type semiconductors (see, for example, “New n-type transparent conducting oxides”, T. Minami, MRS Bulletin, August 2000, p. 38 ff). Therefore, their specific resistance cannot be as low as the corresponding thickness metal film. For example, the resistivity of crystallized indium tin oxide (ITO) film, which is most widely used as the material TCF, typically has a value of approximately 2 · 10 ⁻⁴ Ω · cm. On the other hand, the specific resistance of the aluminum film is typically about 5 · 10 ⁻⁶ Ω · cm. This inherent property of TCF makes it very difficult to actually realize a thin electrode of a thin TCF film with low resistance. On the other hand, to improve the performance of modern displays, very thin conductive electrodes are required to increase the resolution of the display, which means that the lower resistance of the TCF sheet is strongly required. ing.

  There are two different etching techniques that have been developed for industrial applications, the first being wet etching and the second being dry etching. Wet etching processes have been applied to most production lines, which on the one hand have the advantage of requiring only relatively low-cost machines and on the other hand it is an excellent fit for mass production Have sex. However, some experimental parameters, such as etchant composition, etch temperature, etch time, and TCF film surface properties, must be carefully considered in the wet etch process. If the etch rate is too high, side etching and unwanted dendritic pattern formation are easily induced. If the etch rate is too small, the throughput of the etching process is limited. In general, a relatively high etch rate is preferred to save processing costs.

  MC Bartelt et al., Colloids and Surfaces, A, 165 (2000) p. 373 ff, as discussed in general, regardless of whether it is immersion or spraying. At the beginning of the wet etching process, the etchant is adsorbed on the surface of the TCF film. A chemical reaction then occurs at the interface between the etchant and the TCF film. During the course of the etching process, an island structure in the TCF is formed through vacancy nucleation, growing vacancy island adatoms, and fusion of vacancy islands. After the etching process is almost complete, most of the vacancy islands combine and a very small portion of TCF remains unetched away. These remaining portions of the remaining TCF region are commonly referred to as “TCF islands”.

  In practical applications, such as displays, these island structures (TCF islands) induce a short circuit of the respective electrical circuit and consequently destroy the function of the electrodes. Therefore, the appearance of these must be suppressed. A simple way to limit the number of TCF islands and even etch them completely is to increase the etching time. However, manufacturing throughput is reduced by this measure, resulting in increased manufacturing costs.

  Zinc oxide doped with aluminum oxide (AZO) has been described as a possible material for TCF (Y. Igasaki et al., Applied Surface Science, 169-170 (2001) p. 508-511; T. , K. Ellmer et al., Thin Solid Films, 317 (1998) pp. 413-416; T. Minami et al., Thin Solid Films, 366 (2000) pp. 63-68 and M. Miyazaki et al., J of Non-Crystalline Solid, 218 (1997) pp. 323-328). AZO is characterized by good light transmission and is easy to coat by sputtering. However, as a single layer TCF, AZO has worse temperature and chemical stability compared to ITO. However, good temperature and chemical stability are necessary, for example in display applications.

  As mentioned above, TCF must exhibit sufficient stability for chemical products for better reliability in the long term operation of the device. However, TCF also needs to exhibit good etchability to facilitate the manufacture of structured conductive electrodes. Basically, these two requirements are mutually exclusive. Materials with good resistance to chemical products usually have poor etchability and vice versa. Thus, there is a need for an improved TCF that does not show these disadvantages of materials from the prior art, or at least shows them to a lesser extent.

  Liquid crystal displays (LCDs) are widely used to display information. The electro-optic modes used are, for example, the twisted nematic (TN) mode, the super twisted nematic (STN) mode and the electrically controlled birefringence (ECB) mode, various modifications thereof, and other modes. Both of these modes use an electric field substantially perpendicular to the substrate or liquid crystal layer, as well as electro-optic modes such as in-plane switching using an electric field substantially parallel to the substrate or liquid crystal layer. There is also an (IPS) mode (eg compare DE 40 00 451 with EP 0 588 568).

  In addition to a variety of different modes that use the liquid crystal medium itself that is aligned on the surface and typically pre-treated to achieve uniform alignment of the liquid crystal material, a low molecular weight liquid crystal material and a polymer material Complex systems such as polymer dispersed liquid crystal (PDLC) systems, nematic curvilinearily aligned phase (NCAP) systems such as polymer network (PN) systems as disclosed in WO 91/05 029, or Some products use an axially symmetric micro-domain (ASM) system. These composite systems typically use an electric field that is substantially perpendicular to the composite layer.

  LCDs are used not only for direct-view displays but also for projection displays. Besides these applications, LCDs, in particular PDLCs, and in particular LCDs comprising complex systems such as so-called reverse type PDLCs or reverse mode PDLCs known to those skilled in the art are used in practical applications. These reverse type PDLCs provide reverse contrast. That is, they are translucent in the non-powered state and scatter in the applied state, as opposed to normal PDLC. This is generally and preferably achieved by using as the polymeric material a mesogenic polymer that can be oriented before and during the polymerization and is preferably oriented, and thus the orientation is preserved in the liquid crystal system. The

In the composite system, a liquid crystal medium having a relatively high birefringence (Δn) is required in order to achieve an effective scattering state and realize a good contrast. For the reverse type PDLC, Δn must match the Δn of the mesogenic polymer as well as the effective Δn of the mesogenic polymer in the cured liquid crystal system.
Good compatibility with composite polymer precursors and easy phase separation during composite formation are obvious requirements for liquid crystals for such applications.

  In some systems, spontaneous induced phase separation (SIPS) occurs, but in most systems, phase separation does not initiate spontaneously and, more importantly, most That is, it is not completed in this way. Rather, phase separation is initiated by initiating polymerization utilizing an initiator that may be a heat activated initiator or a photoinitiator. For systems in which phase separation is initiated by exposure to heat or radiation, especially for curing by actinic radiation, the liquid-crystalline media must be stable under the exposure conditions. This is especially true for UV cures that otherwise require the use of liquid crystal media that is particularly stable to UV exposure. This is a difficult requirement since the birefringence of the medium should rather increase at the same time.

The most typical undesired compensation is an insufficiently high clearing point, an unfavorably narrow nematic phase range, a rather high temperature at the lower limit of the stability of the nematic phase, a too low dielectric anisotropy and hence a too high operating voltage, Unfavorable elastic constants, too high viscosity values and, last but not least, too low stability or exposure to UV radiation exposure.
Another promising electro-optic mode used in LCDs is the optical compensation bend (OCB) mode. This mode is described, for example, in Yamaguchi et al., “Wide-Viewing-Angle Display Mode for the Active-Matrix LCD Using Bend-Alignment Liquid-Crystal Cell”, SID 93, Digest, p. 277 (1993).

  This mode is very promising. Since this is characterized by advantageous viewing angle dependency, it is particularly suitable for direct-view applications. Also, the response time is extremely short. However, for video rate responses that change the gray scale of the display, the response time needs to be further improved. Compared to conventional TN displays, the amount of deformation of the director is much less in the OCB display. In the TN display, the director is substantially parallel to the substrate in the non-applied state, and when the drive voltage is applied, the direction changes almost perpendicular to the substrate, whereas in the OCB display, the director Although the orientation changes to the same final orientation, it starts from a bent starting state that is already almost homeotropic. Therefore, higher birefringence of the liquid crystal medium used is necessary.

  Therefore, suitable properties for practical applications such as wide nematic phase range, low viscosity, suitable optical anisotropy Δn for the display mode used, especially high Δn suitable for composite systems such as OCB and PDLC, and composite systems For liquid crystal media with a reasonably good compatibility with polymer precursors, especially for composite systems, and with sufficient stability under the curing conditions of the polymer precursors, in particular with actinic radiation There are significant demands.

  Liquid crystal displays (LCDs) are widely used to display information. The electro-optic modes used are, for example, twisted nematic (TN) mode, super twisted nematic (STN) mode, optical compensation bend (OCB) mode and electrically controlled birefringence (ECB) mode, and various modifications thereof. is there. In addition to these modes using an electric field substantially perpendicular to the substrate and the liquid crystal layer, in addition to the modes such as in-plane switching modes (eg those described in DE 40 00 451 and EP 0 588 568) Some electro-optic modes use an electric field substantially parallel to the material and the liquid crystal layer. In particular, this electro-optical mode is used in the latest LCD for desktop monitors.

The liquid-crystalline media according to the invention are preferably used in PDLC displays and in particular in reverse type PDLC displays.
The display according to the invention is preferably addressed by an active matrix (active matrix LCD, AMD for short), preferably by a matrix of thin film transistors (TFTs). However, the liquid crystals of the present invention can also be beneficially used in displays having other known addressing means.

  For these displays, new liquid crystal media with improved properties are needed. In particular, the birefringence (Δn) must be sufficiently high. Furthermore, the dielectric anisotropy (Δε) must be high enough to allow a reasonably low operating voltage. Preferably, Δε should be higher than 6 and very preferably higher than 7 or even higher than 8, but preferably not higher than 15 and in particular not higher than 10. Otherwise, the specific resistance of the mixture tends to be unacceptably low for most AMD. In addition to this parameter, the medium must exhibit a sufficiently wide range of nematic phases, rather low rotational viscosities, and at least a reasonably high resistivity as described above.

  Liquid crystal compositions having a high value of birefringence suitable for LCDs and in particular AMD displays are known, for example, from U.S.P. 5,328,644 and JP 06-264 059 (A). These compositions, however, have significant drawbacks. Most of them, with other disadvantages, have too low a value of birefringence and / or require too high an active voltage. Many of them also have too low resistivity and / or result in an unfavorably long response time and / or poor compatibility with the polymer precursor and / or are sufficiently stable to irradiation is not.

  Therefore, wide nematic phase range, high Δε, suitably high optical anisotropy Δn depending on the display mode used, sufficiently high resistivity, and particularly low viscosity, and excellent stability to irradiation, especially to UV irradiation There is a significant demand for liquid crystal media having properties suitable for practical applications, such as properties.

It has now been surprisingly found that the present invention can provide layered systems, and in particular TCF, that do not exhibit the disadvantages of prior art materials, or at least show them to a lesser extent. These layered systems, in particular TCF, are provided by the realization of innovative multilayer structures and are introduced into various devices, preferably electronic or electro-optical devices. In these layered devices, especially multilayer TCF (MTCF), etchability is conventionally achieved by introducing a buffer layer under the first etchable layer, which itself has better etchability than the first etchable layer. It is significantly higher than the material from the technology.

Thus, one aspect of the present invention is:
-Substrate,
A first solid etchable layer, referred to as a first etchable layer, made of an etchable material, and
-Including a second solid etchable layer, referred to as a buffer layer, which is located between the substrate and the first etchable layer and is made of an etchable material different from the etchable material of the first layer. A layered solid system characterized by
Preferably,
The second etchable layer (buffer layer) has a substantially higher etch rate than the first etchable layer;
More preferably,
A layered solid system is a structured system in which the etchable layer only partially covers the substrate.

Particularly preferred aspects of the present invention are:
-Substrate,
A first solid etchable transparent layer, referred to as a first etchable layer, made of an etchable material, and
A second solid, preferably thin, etch, called a buffer layer, made of an etchable material different from the etchable material of the first layer, located between the substrate and the first etchable layer Possible transparent layer,
A transparent conductive film characterized by being a layered system containing

Another preferred aspect of the present invention is
-Substrate,
A first solid etchable transparent layer, referred to as a first etchable layer, made of an etchable material, and
A second solid, preferably thin, etch, called a buffer layer, made of an etchable material different from the etchable material of the first layer, located between the substrate and the first etchable layer Possible transparent layer,
Structured layered system, including
It is a structured transparent conductive film characterized by containing.

The structured transparent conductive thin film according to the present invention is beneficially used as an electrode in various devices, preferably electric or electro-optical devices, which is also an object of the present invention.
Furthermore, methods for producing layered systems, as well as devices comprising these systems are also objects of the present invention.
In a preferred embodiment of the invention applied to all the above embodiments,
The second etchable layer (buffer layer) has a significantly higher etch rate than the first etchable layer;

  The etch rate is generally defined as the thickness of the layer removed per unit time and is typically given in nm / second. Here, as throughout the application, the etch rate is defined by the average etch rate determined at the time when half the thickness of the etchable material layer is removed, unless otherwise noted. The thickness of each layer can be appropriately measured by using a profiler or an ellipsometer, and it is preferably measured by a profiler.

  When one and the same etchant is used at the same etching temperature, preferably the etching rate of the buffer layer is higher than the first etchable layer, preferably in the range of 5% to 1,000%, more preferably It is higher by an amount in the range of 50% to 500% and most preferably by an amount in the range of 100% to 300%. The initial thickness can be measured with an ellipsometer or profiler. The subsequent etching time for removing 50% of the thickness of the layer can be measured by carefully controlling the etching process. The etch rates of the first etchable layer and the buffer layer can each be determined as the thickness of the layer removed per unit time.

からなる材料の群から選択されるフィルムからなる。好ましい態様では、それは導電性の、好ましくはドープされた酸化物か、または特に好ましくはＩＴＯである。 A preferred etchant used for a multilayer system (MTCF) according to the present invention comprising an ITO film, preferably as the first etchable layer, is described in Example 1 below. Unless otherwise stated, the preferred etching temperature is 45 +/− 1 ° C. This etchant and this etch temperature are also preferred as criteria for determining the etch rate.
Preferably, the first etchable layer is

A film selected from the group of materials consisting of In a preferred embodiment, it is a conductive, preferably doped oxide, or particularly preferably ITO.

Preferably, the buffer layer is simultaneously doped with the following groups of materials: zinc oxide doped with aluminum oxide (abbreviation: AZO), zinc oxide doped with gallium oxide (abbreviation: GZO) or aluminum oxide and gallium oxide. It is made of a material selected from zinc oxide (abbreviation: AGZO), Ag, Au, etc., preferably a material selected from AZO and GZO.
In a preferred embodiment of the invention, the first etchable layer is a transparent, preferably conductive layer. Preferably, the resistivity of the material of the first etchable layer is 10 ⁻² Ω · cm or less, more preferably 10 ⁻³ Ω · cm or less, and most preferably 2 · 10 ⁻⁴ Ω · cm or Less than that.

In a further preferred embodiment of the invention, the buffer layer is a transparent, conductive layer. Preferably, the resistivity of the buffer layer material is 10 ⁻² Ω · cm or less, more preferably 10 ⁻³ Ω · cm or less, and most preferably 2 · 10 ⁻⁴ Ω · cm or less. It is.
And in a particularly preferred embodiment of the present invention, both the etchable layer, the first etchable layer and the buffer layer are each independently of each other and satisfy the preferred conditions of the material resistivity specified for each individual layer. It is a transparent, preferably conductive layer, made of a filling material.

Preferably, the first solid etchable layer has a thickness in the range of 50 nm to 700 nm, more preferably 80 nm to 420 nm, and most preferably 100 nm to 300 nm.
Preferably, the buffer layer has a thickness in the range of 0.1 nm to 50 nm, more preferably 0.5 nm to 40 nm, more preferably 1 nm to 30 nm, and most preferably 4 nm to 26 nm. Have.
Preferably, the thickness of the buffer layer is preferably thinner than the first etchable layer, preferably the ratio of the thicknesses is 1/2 or less, preferably 1/5 or less, and most preferably 1/10 or less.

The transmittance of the MTCF, and in particular the transmittance of the first etchable layer of the MTCF according to the present application, depends inter alia on the required sheet resistance. Preferably, the first etchable layer of MTCF, and in particular MTCF according to the present application, has a transmittance of 70% or more at 550 nm, more preferably a transmittance of 75% or more.
Preferably, the transparent buffer layer of MTCF according to the present application has a transmittance of 70% or more at 550 nm, more preferably 75% or more.

Preferably, the multilayer transparent conductive thin film (MTCF) according to the present application has a transmittance of 75% or more at 550 nm, more preferably a transmittance of 75% or more.
In a preferred embodiment of the present invention, the buffer layer is doped with zinc oxide doped with aluminum oxide (abbreviation: AZO), zinc oxide doped with gallium oxide (abbreviation: GZO), or simultaneously doped with aluminum oxide and gallium oxide. It consists of a film selected from the group of materials consisting of zinc oxide (abbreviation: AGZO).

Preferably, according to the invention, AZO, GZO or AGZO is applied by sputtering. Preferably, 8 atomic% 0.5 atom% or less, preferably to 4 atomic% or more 1 atomic% or less, and made preferably of doped ZnO and most preferably about 2 atomic% of _Al 2 _{O 3} AZO And used as a buffer layer for improving the etching property of the TCF film. Alternatively, but also preferably, from ZnO doped with 0.5 to 8 atomic percent, preferably 1 to 4 atomic percent, and most preferably about 2 atomic percent Ga ₂ O _3. Preferred GZO is used as a buffer layer to improve the etchability of the TCF film. In another embodiment, 0.2 atomic% to 6 atomic%, preferably 0.5 atomic% to 3 atomic%, and most preferably about 1 atomic% of Al ₂ O ₃ and Ga ₂ O ₃ . AGZO, which is preferably composed of ZnO doped in each case, is used.

  When a suitable buffer layer according to the invention as described above is applied between the surface of the substrate and the first etchable layer, i.e. before the deposition of the first etchable layer on the surface of the substrate. The etchant also removes the first etchable layer starting from the surface. Here again, the first etchable layer is etched into an island structure by vacancy nucleation and growth. At some locations, the first etchable layer is etched faster than at other locations. Thus, again in those places where the first etchable layer is etched faster, it will be removed first there. Here, however, the etchant contacts the buffer layer at those locations where the first etchable layer is first removed, and not the substrate itself, as in the prior art. Here, the etchant comes into contact with the buffer layer and reacts with the material of the buffer layer, which is also etched away. Because the etching rate of the buffer layer is higher than that of the first etchable layer, the buffer layer is etched away faster than the rest of the first etchable layer. Thus, the buffer layer is also etched away from the region between the first etchable layer and the substrate that has not yet been completely etched away, and thus the surface of the remaining portion of the first etchable layer that is accessible to the etchant Effectively increases, allowing the etchant to reach between the surface and the rest of the first etchable layer, thus allowing them to be etched away from their “back side” as well. Therefore, the total time required for etching the MTCF is significantly reduced compared to a TCF consisting only of the first etchable layer.

  However, it should be emphasized here that the basic properties of the first etchable layer are preserved by the method of forming a structured electrode according to the invention, as described above, and therefore the properties of the MTCF. It is to decide. Thus, the remaining MTCF in the structured region that is covered by a protective layer, eg, photoresist, and thus not removed by the etching process, determines the electrical properties of the combined layered structure.

The properties of the combined layered structure with respect to chemical resistance, hardness, reliability and stability are also the same or nearly the same as the first etchable layer itself, only the etchability is improved. Due to the island-etching mechanism, the etchant can directly react with the buffer layer to enhance etchability.
Even if the presence of the buffer layer in the multilayer structure has an effect on the optical properties of the structure, it is only minor. According to the theory of optics of thin transparent layers (eg “Thin-film Optical Filters”, H. Macleod, Institute of Physics Publishing, Bristol and Philadelphia, ISBN 0 7503 0688 2 (2001) p. 86 ff.) The influence on the refractive index of each layer of the optical film is expected. It can be tested by experiment or simulated by software.

  In the case where the refractive index of the buffer layer is lower than the overlaid first etchable layer, the transmission increases compared to that of the same first etchable layer used without the buffer layer. This effect is widely used for typical anti-reflective coatings. However, in general, the light transmittance of the layer system according to the present invention can be controlled by optimizing the refractive index and film thickness of the system layer. If the buffer thickness is small compared to the thickness of the first etchable layer, the transmission spectrum over the wavelength of visible light is very similar. The color interference of the layer system does not change significantly and can be controlled by well-known measures.

When AZO is used as a buffer layer and ITO is used as the first etchable layer, the refractive index of the buffer layer of AZO is slightly smaller than that of ITO layered glass, so that the transmittance of the layer system (ITO / AZO) It is relatively easy to control. In particular, the introduction of a buffer layer, for example made of AZO, can even improve the transmission of a system with a first etchable layer of ITO, for example with a thickness of 100 nm or 125 nm.
Preferably, according to the present invention, the composite film including the first etchable layer and the buffer layer is etched in one step.
Unless stated otherwise, the transmission of a layered system (MTCF) is defined as the transmission of visible light, typically given as a percentage at 550 nm. It can be determined as appropriate using a spectrophotometer.

  Unless otherwise stated, the average sheet resistance of MTCF is defined as the conductivity of the conductive layer and is typically given in Ω / □. The well-known four-point probe (Valdes, LG Proc. IRE, 42 (1954) pp. 420-427; Smits, FM, “Measurement of Sheet Resistivity with the Four-Point Probe”, BSTJ, 37 (1958) pp. 711-718 and American Soc. For Testing and Materials, ASTM F 84, Part 43). The electrode of the 4-point probe is copper and the sheet resistance is preferably measured at room temperature. Use a separate 4-point measuring instrument Resisttest RT-80, Napson, Japan.

  The four-point measuring device is assembled from a voltmeter and a measuring circuit. The principle of operation is described, for example, in the referenced references and is only briefly described here. Four probes (sequentially labeled A, B, C, D) contact the surface of the glass plate. These are arranged in a straight line. The distance between any two adjacent probes in succession is 5 mm. A small current, typically 4.53 mA, is generated between the two outermost probes (A and D) and then the voltage between the two central probes (B and C) is measured. The absolute value of the voltage measured between the two central probes (B and C) is proportional to the glass sheet resistance.

The average sheet resistance of the first etchable layer of the MTCF according to the present application, preferably the average sheet resistance of all MTCFs according to the present application is preferably 0.1Ω / □ or more to 60Ω / □ or less, more preferably 1Ω / □ or more to 30Ω / □ or less, particularly preferably 3Ω / □ or more to 20Ω / □ or less, and most preferably 5Ω / □ or more to 15Ω / □ or less, preferably 10Ω / □ or less.
The average time to clear of MTCF according to the present application at 45 ° C. and the conditions given in Example 1 below is preferably 1 second to 800 seconds, more preferably 5 seconds to 300 seconds, more Preferably, it is in the range of 10 seconds to 300 seconds and most preferably 20 seconds to 150 seconds.

The etching rate of the first etchable layer used according to the present application is preferably 0.1 nm / second to 10 nm / second, more preferably 0.2 nm / second to 3 nm / second, and most preferably 0. It is in the range of 3 nm / second or more and 1 nm / second or less.
The etching rate of the buffer layer used according to the present application is preferably 0.15 nm / second to 15 nm / second, more preferably 0.25 nm / second to 8 nm / second, and most preferably 0.35 nm / second. It is in the range of ˜2 nm / second or less.
Unless otherwise stated, all parameter ranges given in this application include extreme values.

Throughout this application, unless otherwise stated, all concentrations are given in weight percent and relate to each complete mixture, all temperatures are in percent (Celsius), and all temperature differences are in percent. Given in. Unless otherwise noted, all physical properties were determined by and determined for "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany. . Optical anisotropy (Δn) is determined at a wavelength of 589.3 nm. The dielectric anisotropy (Δε) is determined at a frequency of 1 kHz. A commercially available Zeiss, Germany spectrophotometer MMS-2 380 nm to 780 nm Messstelle 2 is used for transmission determination. The threshold voltage, as well as all other electro-optical properties, were determined in a test cell prepared by Merck KGaA, Germany. The test cell for the determination of Δε had a cell gap of 22 μm. The electrode was a circular ITO electrode with an area of 1.13 cm ² and a guard ring. The orientation layer was lecithin for homeotropic orientation (ε‖) and polyimide Al-1054 from Japan Synthetic Rubber for homogeneous orientation (ε⊥). Capacities were determined with a frequency response analyzer Solatron 1260 using a sine wave having a voltage of 0.3 V _rms . The light used in the electro-optic measurement was white light. The equipment used was commercially available equipment from Otsuka, Japan. The characteristic voltage was determined under vertical observation. The threshold voltage (V ₁₀ ), mid-grey voltage (V ₅₀ ) and saturation voltage (V ₉₀ ) were determined for relative contrast values of 10%, 50% and 90%, respectively.

  By adding suitable additives, the layered solid system according to the invention, and especially MTCF, can be used in all known types of applications, in particular flat panel display devices with or without such TCF, eg LCD, PDP, Modifications to be usable in OLEDs, ELs, LEDs, FEDs, etc. and in particular in electro-optic systems or for example in solar cells, touch panels, waveguide switches, optical filters and transparent EMI (EMP) shields Can do.

Examples The following examples illustrate this without limiting the invention in any way.
However, these exemplify typical preferred embodiments. These illustrate the use of typical and preferred embodiments and exemplify their structure. In addition, they show possible variations in the electrical, optical properties and stability of the layered system and explain to the person skilled in the art what properties can be achieved and to what extent they can be modified. To do. In particular, the various combinations of properties that can be preferably achieved are thus well defined for the person skilled in the art.

Example 1
A multilayer system was prepared by sequentially depositing a SiO ₂ film, an AZO film and a conventional ITO film on a 1.1 mm thick soda lime glass substrate by sputtering. The layer thicknesses of the three types of films are 25 nm, 6 nm and 120 nm, respectively. These parameters of the layered structure are summarized in Table 1.

注記：*：ＡＺＯ：２原子％のＡｌ_２Ｏ_３を有するＺｎＯ、
ＮＡ：適用せず

Note: *: AZO: ZnO with 2 atomic% Al ₂ O ₃ ,
NA: Not applicable

  The dimensions of the glass substrate are 14 inches × 16 inches and the thickness is 1.1 mm. The sheet resistance of the conductive layer was measured at 9 positions on each sheet with a 4-point probe. These nine positions are located at the center of each of the nine portions of the surface of the substrate, obtained by equally dividing both the length and width of the substrate into three portions as shown in the schematic diagram below.

例１の典型的なシートの９つの領域の中心で得られたシート抵抗の結果を、表２に示す。

注記：シート抵抗：Ω／□

Table 2 shows the sheet resistance results obtained at the center of the nine regions of the typical sheet of Example 1.

Note: Sheet resistance: Ω / □

Next, the optical behavior of the sheet was investigated. The transmittance of the sheet was determined as the transmittance compared to air at 550 nm. The results of these tests are included in Table 1.
Next, the etching behavior of the sheet was determined. The etchant used consisted of 48.4% by volume HCl aqueous solution (> 32%), 3.8% by volume HNO ₃ (65%) and 48.1% by volume deionized water. The observed etch rates are also included in Table 1.
The “removal time”, defined as the etching time to completely remove the layer, is determined as 90 seconds at a temperature of (45 +/− 1) ° C. and 240 seconds at a temperature of (30 +/− 1) ° C. It was. The results of these tests are also included in Table 1. Here, when the obtained sheet resistance is larger than 1 · 10 ⁵ Ω / □, it is defined that the layer is completely removed.

The sheet was then examined for the formation of microstructures during etching. The same etching solution was used for determining the etching rate and for determining the removal time. Conventional photolithography techniques were applied to the etching pattern. Photoresist material (Clariant, AZ AFP-750ε750 from Switzerland) was applied to one surface of the sheet with a spin coater from Kondo-Seimitsu, Japan. Heat (pre-bake) for 90 seconds at 100 ° C, then expose with MA-5601-ML exposure machine, DNK, Japan with a radiation flux of 70 mJ at a radiation power of 35 mW / cm ² and 2.38% tetramethyl hydroxide After development by immersion in ammonium at 23 ° C. for 60 seconds, the sheet was again heated this time at 220 ° C. for 70 minutes (post-baking). Then, the wet etching process was performed at the temperature of (45 +/- 1) degreeC. The etching process was interrupted at various times and the results were observed under a microscope. After 30 seconds, the ITO was clearly seen etched into the island structure in areas not covered by the photoresist, while the other areas were not etched at all. After a time of 120 seconds, the remaining ITO-islands were no longer observed.

Finally, the sheet was subjected to a reliability test consisting of 5 separate tests.
First, the “adhesive tape test” was performed according to MIL-M13508 4.4.6, and the sheets were examined for changes in appearance visible to the naked eye under normal illumination.
Second, apply the “rubber test” according to MIL C-675-C 4.5.10 with rubber according to MIL EE-12397-B and again under normal illumination. The sheets were examined for changes in the appearance that can be visually recognized.
Third, the chemical stability in NaOH was tested in a 5% strength sodium hydroxide solution at 55 +/− 1 ° C. for 30 minutes under ultrasonic agitation. The results of the test for chemical stability in NaOH were determined by the sheet resistance obtained and its change during the test.

Fourth, temperature stability was determined. This is the sheet resistance after completion of the temperature cycle consisting of heating the sheets to 300 ° C. within 40 minutes, maintaining them at 300 ° C. for 30 minutes, and then allowing them to cool to ambient temperature in ambient air for 120 minutes. Defined as a change in
Fifth, humidity stability was determined. This is defined as the change in sheet resistance after 24 hours of treatment at a temperature of 60 +/− 2 ° C. and a relative humidity of 90 +/− 5%.
The sheet prepared according to this example passed all five stability tests and the results are included in Table 1.

Comparative Example 1-1
A multilayer system is prepared as in Example 1, except that the AZO film is not deposited below the ITO film. The thickness values for each of the multilayer systems are also shown in Table 1 for comparison. This multilayer system is available as “MDT # 300 fully oxidized ITO glass”, a typical ITO-coated glass for STN display applications, from Merck Display Technologies, Taiwan, a company of Merck Group.
Table 3 shows the results of sheet resistance obtained in nine spots of a typical sheet of Comparative Example 1-1.

注記：シート抵抗：Ω／□

Note: Sheet resistance: Ω / □

From the comparison between the results in this table and the results in Table 2, it is clear that the sheet resistance of Example 1 is very similar to that of this Comparative Example and Comparative Example 1-1.
Again, the optical behavior of the sheet was investigated. The transmittance of the sheet was determined as the transmittance compared to air at 550 nm. The transmittance at 550 nm of this comparative example and comparative example 1-1 shown in Table 1 is very similar to that of Example 1.
The removal time was determined here to be 500 seconds at a temperature of (45 +/− 1) ° C. and more than 1500 seconds at a temperature of (30 +/− 1) ° C.

The sheet was then examined for the formation of microstructures during etching as described in Example 1. After a time of 120 seconds, there was a clearly visible area of ITO that was not covered by the photoresist and was not etched or only partially etched. After 360 seconds, no unetched or partially etched areas were observed anymore. However, some residual ITO islands remained.
The sheet passed all five stability tests performed as described in Example 1. The results are shown in Table 1.

注記：シート抵抗：Ω／□ Comparative Example 1-2
In this comparative example, the multilayer system is again prepared as in Example 1, but here only the AZO film is deposited and no ITO film is deposited. The thickness values for each of the multilayer systems are also shown in Table 1 for comparison.
Table 4 shows the sheet resistance results obtained with nine spots of a typical sheet of Comparative Example 1-2.

Note: Sheet resistance: Ω / □

From this table, the sheet resistance of Example 1 is significantly lower than this comparative example, Comparative Example 1-2, and therefore the sheet of Example 1 is much more suitable for practical use than that of Comparative Example 1-2. It is clear.
Again, the optical behavior of the sheet was investigated. The transmission of the sheet was again determined as the transmission compared to air at 550 nm and the results are included in Table 1 which are very similar to the results of Example 1 and Comparative Example 1-1.

The removal time was determined here as 60 seconds at a temperature of (45 +/− 1) ° C. and 45 seconds at a temperature of (30 +/− 1) ° C. During the etching process, the AZO film was peeled off, and the peeled film could be observed in the etching solution by human visual inspection.
The sheet was then examined for the formation of microstructures during etching as described in Example 1. The results are shown in Table 1.
The sheet was subjected to the five stability tests described in Example 1 above. These sheets passed the first two stability tests, but the remaining three stability tests clearly failed.

Summary of comparison between Example 1 and Comparative Examples 1-1 and 1-2
Compared to the ITO glass of Comparative Example 1-1, which is a typical ITO glass for STN applications available from Merck Display Technologies, Taiwan, a company of Merck Group, the multilayer system of Example 1 according to the present invention is similar. It has the following electrical and optical properties. Both sheets of Example 1 and Comparative Example 1-1 passed all five reliability tests. However, the etching behavior of the multilayer system of Example 1 according to the present invention showed a clearly different etching mechanism and a greatly improved removal time. It could be etched into the temporary mesh shape that often occurs within a significantly shorter time. In addition, this semi-etched layer could be quickly removed from the substrate surface. Under typical conditions used in the manufacture of electro-optic displays, the multilayer system of Example 1 according to the present invention saves approximately 82% of the time required for the wet etching process compared to the system of Comparative Example 1-1, Furthermore, no ITO-island remains.

  The system of Comparative Example 1-2 is significantly larger than both the system of Example 1 and Comparative Example 1, and therefore has a better etch rate and consequently shorter and better removal time, but the device For example, it cannot be easily applied to practical manufacture of STN displays. It was clearly higher than the other two systems and thus had worse sheet resistance and failed for three of the five reliability tests performed.

Example 2
Similar to Example 1, a multilayer system was prepared by sequentially depositing a SiO ₂ film, an AZO film and a conventional ITO film on a 1.1 mm thick soda lime glass substrate by sputtering. Here, however, the layer thicknesses of the three films are 35 nm, 24 nm and 145 nm, respectively. These parameters of the layered structure are summarized in Table 5.

注記：*：ＡＺＯ：２原子％のＡｌ_２Ｏ_３を有するＺｎＯ、
ＮＡ：適用せず

Note: *: AZO: ZnO with 2 atomic% Al ₂ O ₃ ,
NA: Not applicable

注記：シート抵抗：Ω／□ The dimensions of the glass substrate are the same as those used in Example 1. The sheet was subjected to the same investigation and testing as described in Example 1. The results of these tests are included in Table 5.
The sheet resistance results obtained with 9 spots of the typical sheet of Example 2 are shown in Table 6.

Note: Sheet resistance: Ω / □

Next, the optical behavior, etching behavior and removal time of the sheet were investigated. The results of these tests are included in Table 5.
The sheet was then examined for the formation of microstructures during etching. The results of these tests are also included in Table 5.
Finally, the sheet was subjected to five separate reliability tests as described in Example 1. The sheet passed all five stability tests. The results of these tests are also included in Table 5.

注記：シート抵抗：Ω／□ Comparative Example 2
A multilayer system is prepared with the same ITO film and SiO ₂ film as applied in Example 2 as in Example 1, but here, as in Comparative Example 1-1, the AZO film is deposited under the ITO film. Not. The thickness values for each of the multilayer systems are also shown in Table 5 for comparison. This multilayer system is available from Merck Display Technologies of Taiwan as “MDT # 370 fully oxidized ITO glass”, a typical ITO coated glass for STN applications.
Table 7 shows the sheet resistance results obtained with nine spots of a typical sheet of Comparative Example 2.

Note: Sheet resistance: Ω / □

From this table, it is clear that the sheet resistance of Example 2 is very similar to that of Comparative Example 2 and Comparative Example 2.
Again, the optical behavior of the sheet was investigated. The transmittance of the sheet of Example 2 is slightly lower than that of Comparative Example 2 and Comparative Example 2.
The removal time was determined here as 580 seconds at a temperature of 45 ° C.
The sheets of Comparative Example and Comparative Example 2 passed all of the five stability tests described in Example 1. The results are shown in Table 5 for comparison.

Overview of Comparison between Example 2 and Comparative Example 2 Compared to the ITO glass of Comparative Example 2, the multilayer system of Example 2 according to the present invention has similar electrical and optical properties. Both the sheets of Example 2 and Comparative Example 2 passed all five reliability tests. However, the etching behavior of the multilayer system of Example 2 according to the present invention showed a clearly different etching mechanism and a greatly improved removal time. Under typical conditions used in the manufacture of electro-optic displays, the multilayer system of Example 2 according to the present invention saves approximately 83% of the time required for the wet etching process compared to the system of Comparative Example 2, and further residual No ITO islands are observed.

Example 3
A multilayer system was prepared as in Example 1 by sequentially depositing a SiO ₂ film, a GZO film and a conventional ITO film on a 1.1 mm thick soda lime glass substrate by sputtering. The layer thicknesses of the three types of films are 25 nm, 6 nm and 120 nm, respectively. These parameters of the layered structure are summarized in Table 8.

注記：*：ＧＺＯ：２原子％のＧａ_２Ｏ_３を有するＺｎＯ、
ＮＡ：適用せず

Note: *: GZO: ZnO with 2 atomic% Ga ₂ O ₃ ,
NA: Not applicable

注記：シート抵抗：Ω／□
シートの透過率は、５５０ｎｍにおける空気と比較した透過率として決定し、表８に含めてある。
観察されたエッチング速度、および（４５＋／−１）℃の温度で８５秒と決定された除去時間もまた、表８に含めてある。 The sheet was investigated as described in Example 1.
The sheet resistance results obtained with 9 spots of the typical sheet of Example 3 are shown in Table 9.

Note: Sheet resistance: Ω / □
The transmittance of the sheet is determined as the transmittance compared to air at 550 nm and is included in Table 8.
The observed etch rate and removal time determined to be 85 seconds at a temperature of (45 +/− 1) ° C. are also included in Table 8.

The sheet was then examined for the formation of microstructures during etching. The same etching solution was used for determining the etching rate and for determining the removal time. Conventional photolithography techniques were applied to the etching pattern. Photoresist material (Clariant, AZ AFP-750ε750 from Switzerland) was applied to one surface of the sheet with a spin coater from Kondo-Seimitsu, Japan. Heat (pre-bake) for 90 seconds at 100 ° C, then expose with MA-5601-ML exposure machine, DNK, Japan with a radiation flux of 70 mJ at a radiation power of 35 mW / cm ² and 2.38% tetramethyl hydroxide After development by immersion in ammonium at 23 ° C. for 60 seconds, the sheet was again heated this time at 220 ° C. for 70 minutes (post-baking). Then, the wet etching process was performed at the temperature of (45 +/- 1) degreeC. After 120 seconds, the remaining ITO-islands were no longer observed.
Finally, the sheet was subjected to the five reliability tests described in Example 1. The results of these tests are included in Table 8. The sheet passed all five stability tests.

注記：シート抵抗：Ω／□ Comparative Example 3
A multilayer system is prepared as in Example 3, but here no GZO film has been deposited. The thickness values for each of the multilayer systems are also shown in Table 8 for comparison. This multilayer system is available from Merck Display Technologies of Taiwan as “MDT # 300 fully oxidized ITO glass”, a typical ITO coated glass for STN applications.
Table 10 shows the sheet resistance results obtained with nine spots of a typical sheet of Comparative Example 3.

Note: Sheet resistance: Ω / □

From this table, it is clear that the sheet resistance of Example 3 is very similar to that of Comparative Example 3 and Comparative Example 3.
Again, the optical behavior of the sheet was investigated. The transmittance of the sheet was determined as the transmittance compared to air at 550 nm. Here, the transmittance at 550 nm was very similar to the comparative example and comparative example 3.
The removal time was determined here as 500 seconds at a temperature of (45 +/− 1) ° C.
The sheet passed all five stability tests described in Example 3. The results are also shown in Table 8.

Overview of comparison between Example 3 and Comparative Example 3
Compared to the ITO glass of Comparative Example 3 available from Merck Display Technologies, Taiwan, the multilayer system of Example 3 according to the present invention has similar electrical and optical properties. All examples passed all five reliability tests. However, the etching behavior of the multilayer system of Example 3 showed a distinctly different etching mechanism and a greatly improved removal time. Under the typical conditions used in the manufacture of electro-optic displays, the multilayer system of Example 3 saves approximately 83% of the time required for the wet etching process compared to the system of Comparative Example 3, and the remaining ITO islands. Is not observed.

Claims (19)

-Substrate,
A first solid layer, referred to as a first etchable layer, made of an etchable material, and
A layered solid system comprising a second solid layer, referred to as a buffer layer, located between the substrate and the first etchable layer and made of an etchable material.   The system according to claim 1, characterized in that the buffer layer has an etch rate substantially higher than that of the first etchable layer.   The system according to any of claims 1 and 2, characterized in that the etching rate of the buffer layer is higher than the first etchable layer by an amount in the range of 5% to 1,000%.   The system according to claim 1, wherein at least one of the first etchable layer and the buffer layer is a transparent layer.   The system according to claim 4, characterized in that both the first etchable layer and the buffer layer are transparent layers.   6. A system according to any one of the preceding claims, characterized in that at least one of the first etchable layer and the buffer layer is a conductive layer.   7. A system according to claim 6, characterized in that both the first etchable layer and the buffer layer are conductive layers.   System according to any of the preceding claims, characterized in that the first etchable layer consists of ITO.   System according to any of the preceding claims, characterized in that the buffer layer is made of a material selected from the group of materials AZO, GZO and AGZO.   The system according to claim 1, wherein the buffer layer has a thickness in the range of 0.1 nm to 50 nm.   The system according to any one of claims 1 to 10, characterized in that the sheet resistance at 20 ° C of one or more conductive layers is in the range of from 0.1 Ω / □ to 100 Ω / □.   System according to any of the preceding claims, characterized in that the transmission at 550 nm of the system is 70% or above.   13. The substrate according to claim 1, wherein the substrate is structured into areas covered by the first and second etchable layers and areas not covered by these layers. The system described in Crab.   A device comprising the system according to claim 1.   The device according to claim 14, wherein the device is an electro-optic device.   Use of the system according to any one of claims 1 to 13 for an electro-optical device.   A method for producing a structured system using the layered system according to any of claims 1-12.   A method for manufacturing an electro-optic device, characterized in that the system according to claim 1 is used. The substrate is by at least two etchable layers;
-First by a buffer layer made of an etchable material;
A process for producing a structured system, characterized in that it is continuously coated.