JP6747970B2 - Touch sensor device - Google Patents

Description

Touch sensors are used in various electronic devices such as navigation systems, copy machines, and PC systems, and in recent years, mobile phones, smartphones, tablet PCs, PDAs (personal digital assistants), portable music players. It is often used in mobile devices such as. In this case, the touch sensor is often arranged on a display unit, such as a liquid crystal (LCD) or OLED (organic light emitting diode) display screen, for example, or integrated into such a display unit, so-called touch screen. Form a touch panel. Such a touch panel allows the user to intuitively operate the electronic device, and the user can communicate with the electronic device by touching the surface of the touch sensor with a finger, pen or other object. You can

Various physical methods are known for sensing touch points, which are based on, for example, optical, acoustic, resistive or capacitive sensing. Most touch panels available on the market are based on resistive or capacitive sensing. The basic structure of a capacitive touch sensor device consists of at least two conductive layers, which are applied to an electrically insulating substrate, can be activated selectively and function as electrodes of a touch sensor. If an insulating or conducting material is moved in the immediate vicinity of the sensor, it causes a change in capacitance between the two conducting layers, which is detected and analyzed by means of the corresponding analysis unit. The two conductive layers are applied to opposite sides of the substrate as disclosed in US Pat. In the case of a device on one side of the substrate, the electrodes are typically arranged in a two-dimensional grid, where the individual electrodes are arranged in a grid and intersect and overlap each other, at the point of overlap, electrical They are separated from each other by an insulating layer.

For application of the touch sensor in a touch screen, the touch sensor must be implemented transparent in the light area so that the user can see the display unit as unobtrusively as possible. To this end, a transparent conductive oxide (TCO), such as indium-tin oxide (ITO), indium-zinc oxide (IZO) or aluminum-zinc oxide (AZO), a conductive polymer film, or similar. It is known to manufacture electrodes from materials. As a result of the low conductivity of these materials and the difficulties in the manufacturing process, in practical applications it is necessary to bridge the electrodes at the points where they intersect with a metal contact structure, also called a metal bridge. In the simplest embodiment, these bridging contact structures are constructed as a single layer from Al, Mo, Cu, Ag or Au or alloys of these metals with good conductivity. In addition, multilayer embodiments are also known. In particular, in order to improve the adhesion of the contact structure to the transparent electrode, MO _x ·Ta _y (between the transparent electrode to be contacted with the metal layer having good conductivity such as Al, Cu or Ag). Patent Document 2) or may be provided _MO x · Nb _y made of metal intermediate layer.

The metal contact structure does increase the conductivity sufficiently for the function of the touch screen, but it has the drawback of impairing the appearance of the touch screen as a result of its reflectivity in the visible range. In its deactivated state, the touch screen becomes visible to the user in the ambient light when the display unit is dark. This is because the metal structure strongly reflects ambient light. To suppress the reflection of these _unwanted known to laminate MoO _x, a MO x _Ta y _{O z} or _Mo x _Nb y _O light absorbing layer made of metal oxide such as _z contact structure ing. Patent Document 1 discloses, for example, a multilayer contact structure made of a metal layer such as Mo and a light absorbing layer made of a metal oxide such as MoO _x , in which a light absorbing oxide layer is provided. Overlap with the metal layer, thereby suppressing some of the unwanted reflections.

Both this thin conductive layer and the contact structure are typically manufactured by vapor deposition using a suitable sputtering target, where subsequent structuring of the individual layers is based on wet chemical etching. It is carried out by photolithography using a combined process. To make a multilayer contact structure, it is advantageous if the materials of the individual layers of the contact structure have similar etching rates. This is because in this case the etching process can be carried out in one step and the etching medium does not have to be adapted to the structure of the individual layers, which reduces the manufacturing costs. The etching properties are unsatisfactory, especially in the case of Mo/MoO _{x in} the above example. This is because the etch rate of the oxide layer MoO _x is significantly different from the etch rate of the metal layer (in the phosphoric acid, acetic acid and nitric acid based etching solutions typically used in the manufacturing process).

In addition to optical requirements and advantageous etching behavior, the contact structure must meet further requirements. In particular, mobile devices are exposed to a high degree of stress (corrosion, moisture, sweat, etc.) due to environmental influences during operation, and damage to the contact structure occurs due to corrosion or other reactions that change the electrical properties. Therefore, the function of the touch sensor may be impaired.

In short, the touch sensor contact structure must meet a wide variety of electrical, chemical and optical requirements. In order for the sensor to have sufficient measurement accuracy and speed, the contact structure must have a sufficiently high conductivity and must meet the lowest possible boundary resistance to the transparent conductive electrode to be contacted. .. The contact structure should also not be visually perceptible by the user, if possible, both during operation with the display unit arranged behind it and when the display unit is not in operation. Furthermore, the material used must have a high degree of corrosion resistance and resistance to external influences, while the material of the contact structure must be well processable during manufacturing by etching processes. That is, the material of the contact structure must be well etched or have good etching behavior. Furthermore, in the case of multilayer contact structures, the etching properties of the materials used in the individual layers must be similar for more cost-effective production.

JP, 2013-20347, A US Patent Application Publication No. 2011/0199341A1

It is an object of the present invention to provide a touch sensor device with a contact structure which has the most advantageous properties possible with respect to the performance requirements mentioned above.

This object is achieved by a touch sensor device according to claim 1. Advantageous refinements can be inferred from the dependent claims. The method of manufacturing the touch sensor display unit and the contact structure of the touch sensor device according to the present invention are also part of the present invention.

The touch sensor device according to the invention comprises an optically transparent and electrically insulating substrate on which at least one optically transparent and electrically conductive sensor element is arranged. Typically, multiple sensor elements are provided, which can be selectively electrically activated and tightly localized to the contacts. Furthermore, the touch sensor device comprises at least one contact structure for electrically contacting said optically transparent and electrically conductive element(s), which contact structure according to the invention comprises a metal oxynitride. Made of at least one layer. Here, the metal forming oxynitride contains one element or a combination of a plurality of elements selected from the element group consisting of niobium, tantalum, vanadium, tungsten, chromium, rhenium, hafnium, titanium and zirconium. Accordingly, the metal oxynitride is a composition of the type Mo _a X _b O _c N _d , where X is an element selected from the group of Nb, Ta, V, W, Cr, Re, Hf, Ti and Zr. This is a combination of a plurality of elements selected from the group of Nb, Ta, V, W, Cr, Re, Hf, Ti and Zr.). It should be understood that the formula Mo _a X _b O _c N _d is not a chemical formula in a strict sense, but rather merely represents the relative atomic composition of the metal oxynitride. Therefore, the subscripts a, b, c, and d are atomic percentage definitions and add up to 1. X may be absent, so the relative proportion of b may be zero. Preferably X is niobium or tantalum. Alternatively, preferably b=0. It should be noted here that the metal oxynitride does not have to have an extremely pure composition, but rather contamination by other elements may be present. Here, the reflectivity of the layer made of said oxynitride is less than 20%, in particular less than 10%.

It should be understood that “contact” means not only direct contact by direct physical contact, but rather also the approach of an object in the vicinity of the sensor element. Therefore, the touch sensor device does not only detect when touching the touch sensor device with a finger, a stylus or other object, but also when they are brought in the vicinity of the touch sensor element. Should be understood as a device that does. Touch sensor devices can be provided for capacitive or resistive sensing of contacts, among others.

“Optically transparent” should be understood to mean that each layer or structure is substantially transparent to all or part of the visible electromagnetic spectrum.

"Reflectance" should be understood as the ratio of the reflected and incident light flux. Scattered and backscattered light should also be considered in the reflected light bundle. This is the dimension of the optical measurement, in which the reflective performance of the layer is characterized in view of the wavelength-dependent sensitivity of the human eye (daylight, for photopic vision). In a first approximation, the reflectance R (%) at 550 nm was used to measure the reflectance of the layers produced according to the invention. The sensitivity of the human eye (brightness sensitivity, V lambda curve) is highest at this wavelength.

Optically transparent and conductive sensor elements include transparent conductive oxides (TCO) such as indium-tin oxide (ITO), indium-zinc oxide (IZO) or aluminum-zinc oxide (AZO), PEDOT. : PSS (poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate)) and the like, and may have a transparent conductive polymer, carbon nanotubes or graphene.

The use of metal oxynitrides in the layers or intermediate layers of the contact structure is advantageous both from the application point of view (advantageous optical reflection behaviour, sufficiently high conductivity) and from the point of view of manufacturing touch-sensitive devices. The layers of a touch-sensitive device are typically the one or more layers that are first deposited on a large area of a substrate by known thin film coating techniques such as PVD (physical vapor deposition) or CVD (chemical vapor deposition). Then, it is manufactured by being structured by a photolithography process and further processed in a subsequent etching process. Here, the metal oxynitride layer can be deposited by using a metal target made of molybdenum or a molybdenum alloy under the supply of oxygen or nitrogen as a reactive gas (so-called reactive sputtering). Compared to the manufacturing process of a metal oxide layer, which, due to the additional use of nitrogen, reacts very sensitively to process parameter fluctuations that occur only under oxygen supply (eg as proposed in US Pat. Can lead to improved stability and reproducibility of the coating process. The etching properties of the layer made of metal oxynitride have to be mentioned as a further advantageous property in the manufacturing process. The layer made of metal oxynitride exhibits good etching properties in the industrially used mixture of phosphoric acid, nitric acid and acetic acid and is therefore well structured in industrially common wet chemical etching processes. be able to.

A metal oxynitride layer in which the ratio of oxygen to nitrogen expressed in atomic% is 3:1 to 9:1, that is, the layer contains at least 3 to 9 times as many oxygen atoms as the number of nitrogen atoms in the layer, It has been found that overall, in terms of reflection properties, conductivity and etching properties in mixtures of phosphoric acid, nitric acid and acetic acid, very advantageous properties are exhibited. For this layer made of Mo _a X _b O _c N _d , 3≦c/d≦9 applies. By varying the oxygen or nitrogen ratio, individual industrial material properties can be optimized. Pure molybdenum nitride exhibits distinct metallic properties with respect to its electrical properties (conductivity is lower than that of metals, but electrical resistance remains in the range of metallic conductors, and molybdenum nitride is strong in the optical range). In contrast, the electrical properties of pure molybdenum oxide with a suitable quasi-stoichiometric oxygen ratio, as proposed for example in US Pat. Diverge. They are dark and have a low reflectance in the optical range. The conductivity is lower and is characterized by ionic conduction. By partially replacing oxygen atoms with nitrogen atoms, the point of optical reflection behavior while maintaining or improving the electric resistance value (electric resistance Rs≦3,000 Ω/area) required for application in a touch sensor. It has been found that the advantageous properties of molybdenum oxide can be achieved. At the same time, by changing the ratio of nitrogen to oxygen, a degree of freedom can be obtained, which can be used to change the etching rate of molybdenum oxynitride within a specific range and adapt to the etching rate of molybdenum or molybdenum alloy. Can be made.

In a preferred embodiment of the metal oxynitride layer Mo _a X _b O _c N _d , the following relationships hold. 0≦b≦0.25a, 0.5≦c≦0.75, 0.01≦d≦0.2, a+b+c+d=1 and c+d≦0.8. Particularly preferably, the following relationships hold for the metal oxynitride layer. 0≦b≦0.2a, 0.55≦c≦0.7, 0.01≦d≦0.15, a+b+c+d=1 and c+d≦0.8. In this case, the advantages mentioned above are achieved to a greater extent.

The contact structure may have one or more layers made of one or more materials in addition to the layer made of metal oxynitride. In a preferred embodiment, the contact structure may be constructed in multiple layers, in particular two or three layers, in addition to the layers made of metal oxynitride, the contact structure may be Al, Mo, Cu, Ag or Au or these. May have a metal layer made of an alloy based on one of the metals (“based” means that the proportion of the alloy's major components is greater than 90 atom %), whereby , A higher conductivity of the contact structure is achieved. Here, the layer made of metal oxynitride is mounted upstream of the metal layer (in the direction of the user's line of sight of the touch sensor device) in order to achieve the advantageous reflective behavior of the touch sensor device. The reflective properties of the contact structure can be further optimized by taking advantage of the interference effect due to the change in layer thickness of the metal oxynitride layer.

The touch sensor device may be implemented in an exemplary embodiment according to the invention for resistive or capacitive sensing of touch points. The touch sensor device is preferably embodied, for example, as a projected capacitive touch sensor as described in US Pat. Here, the touch sensor device has a plurality of sensor elements, and these sensor elements are divided into two groups and arranged in a grid shape, and function as electrodes of the touch sensor. "Arranged in a grid" should be understood to mean that the touch-sensitive elements are arranged at different positions on the surface of the substrate in a predefined pattern, for example a chess board. Is. However, the grid is not limited to right angle arrays. Therefore, the plurality of first sensor electrodes are arranged at different positions in the first direction, and the plurality of second sensor electrodes are arranged at different positions in the second direction. At, they are separated from each other by an electrically insulating layer. The group of sensor electrodes is blocked at the intersection by an electrically insulating layer. Contact structures with metal oxynitrides bridge or contact these electrodes, which are originally electrically isolated.

In addition to bridging contact at the intersection of the transparent electrodes, the contact structure of the present invention having a metal oxynitride layer provides electrical contact of the transparent electrode with the activation and analysis unit for further processing of electrical signals. May be. The bonding with the metal layer thus achieves a highly conductive electrical contact in the visible range of the touch sensor device, which at the same time meets the high requirements of optical reflection.

According to the invention, the touch sensor device may form part of a touch sensor unit, a so-called touch panel. Here, the touch sensor device may be embodied as a separate unit, or may be attached to a display unit such as a liquid crystal (LCD) or OLED (organic light emitting diode) display screen, a so-called "out cell" touch sensor device. May be formed (see Patent Document 1, FIG. 3a). The touch sensor device may be more firmly incorporated into the display unit to form a thinner touch panel. Thus, for example, the individual components of the touch-sensitive device, eg the transparent substrate, may simultaneously form the components of the LCD display screen (“on-cell” touch-sensitive device. The touch-sensitive device is therefore located behind it). It does not have a separate substrate from the display screen, and does not have a separate substrate from the display screen, see US Pat. See U.S. Pat. No. 8243027). In the case of a multilayer embodiment of the contact structure according to the invention made of a metal layer and a metal oxynitride layer, the layer having the metal oxynitride in the sequence of layers is arranged farther from the display unit made of metal layer than the metal layer. It should be noted that In the viewing direction of the user of the touch panel, the metal oxynitride layer is thus mounted upstream of the metal layer and hides it.

The invention will now be described in more detail on the basis of an exemplary embodiment with reference to FIGS. 1a, 1b, 2a and 2b. 1a and 2a are identical and schematically show a plan view of the structure of a touch sensor device according to the present invention, wherein layered structures of various contact structures are respectively enlarged in sectional views in FIGS. 1b and 2b. Indicate. Here, a cross section of the touch sensor device is shown in FIGS. 1a and 2a, which is indicated by a dotted line. The touch sensor device 10 is a part of a touch panel, and has an optically transparent substrate 1 made of an electrically insulating material such as glass or transparent plastic. Within the scope of the embodiment as an "on-cell" touch sensor device, the substrate of the touch sensor device simultaneously forms the color filter substrate of the LCD display screen. However, the substrate may also be formed as a separate substrate. The exemplary embodiment is based on capacitive sensing of touch, and corresponds in function and structure to the projected capacitive touch panel in US Pat. The electrodes required for capacitive sensing are formed by a plurality of layered touch sensor elements 2x and 2y, which are arranged in a grid composed of rows (rows) and columns (columns) on the same side of the substrate. It is arranged in a chessboard-like pattern and is constructed from an optically transparent, electrically conductive material, such as indium-tin oxide. For illustration purposes, the two electrodes are shaded differently in the figure. The electrodes are electrically separated from each other at the intersections by an electrically insulating layer 3. Here, one group of touch sensor elements, for example 2y, is electrically conductively coupled to each other at each corner in the vertical direction, while the other group 2x of touch sensors is initially electrically connected. It has been cut off. This is caused by the electrically insulating layer 3. The groups of touch sensor elements 2x are in horizontal electrical contact by the bridging contact structure 4. In the present exemplary embodiment, it is constructed from three layers, made of molybdenum oxynitride layer 5 and Al, Mo, Cu, Ag or Au or alloys based on one of these metals. It has a metal layer 6 made of a highly conductive metal. Furthermore, a further metal layer 7 made of Mo, W, Ti, Nb or Ta or an alloy based on one of these metals is provided as a cover layer. Here, it is preferred to use the same metal or alloy as that used in the oxynitride layer. Layer 7 is used as a protective layer (for mechanical damage, corrosion, moisture, sweat, etc.) of the diffusion barrier and/or the underlying layer 6 of highly conductive metal. The molybdenum oxynitride layer is mounted upstream of the two metal layers in the viewing direction 20 of the touch panel user to hide them.

Each row of touch sensor elements 2x, like each column of touch sensor elements 2y, is electrically connected to activation and analysis electronics (not shown in the figure). Activation and analysis electronics detect the touch-induced capacitance change and analyze it with respect to the position of the touch. The electrical connection is made by the contact structure 4'at least in the area of the touch panel visible to the user. The contact structure 4', like the bridge contact structure 4, is built in three layers and is based on a layer 5 made of molybdenum oxynitride, Al, Mo, Cu, Ag or Au or one of these metals. It has a metal layer 6 made of an alloy and a metal layer 7 made of Mo, W, Ti, Nb or Ta or an alloy based on one of these metals.

The layers of the touch sensor element and the contact structure 4 or 4'are extensively deposited by sputter deposition with the corresponding target, where the formation of the metal oxynitride takes place under the supply of oxygen and nitrogen. The coated layer is structured by photolithography and subsequent wet chemical etching using an etching solution consisting of phosphoric acid, nitric acid and acetic acid (PAN etching solution).

Within a series of experiments, various layers of molybdenum oxynitride with different compositions were produced and their properties were compared in Table 1 with the corresponding metal, metal oxide and metal nitride layers. .. In each case, a pure molybdenum target, a molybdenum alloy target with 6 at% tantalum or a molybdenum alloy target with 10 at% niobium was used as the sputtering target. Molybdenum oxynitride layer, a metal target, and reactive sputtering using air _/ O ₂ / N 2 mixture. Here, the relative proportions of the reactive gases in the process is _{O 2} about 33 vol% for the oxide, it was _{O 2} about 23 vol% and _{N 2} to about 15 vol% for oxynitride. The process gas pressure was about 5×10 ⁻³ mbar.

To determine the reflectance, glass substrates (Corning Eagle XG, 50×50×0.7 mm ³ ) were coated with molybdenum oxynitride or reference material and a cover layer made of 250 nm Al. Here, the third metal layer is omitted. Because it has no effect on the measurement result. The reflectance was measured through a glass substrate (in the direction of the line of sight of the observer 20) using a Perkin Elmer Lambda 950 Photo Spectrometer. In order to obtain the lowest possible reflectance, the layer thickness of molybdenum oxynitride was varied in the range 35-75 nm, but the best results were achieved in the range 40-60 nm.

The electrical resistance of molybdenum oxynitride and the reference material were measured based on a sample coated with a 55 nm thick layer of glass substrate. The measurements were carried out using a 4-point method (commercially available 4-point measuring head).

A 300 nm thick layer was used in each case to measure the wet etch rate. Wet etch rate was measured at 40° C. in a stirred PAN solution with 66% phosphoric acid, 10% acetic acid and 5% nitric acid and water (balance). Here, the samples were each immersed in the etching solution for 5 seconds, then rinsed and dried. The dried sample was then weighed on a precision balance. These steps were repeated until the entire layer had dissolved. The etching rate was calculated from the mass reduction with respect to the etching time.

* Indicates an example of the present invention.

The sample with molybdenum oxynitride exhibited improved reflection behavior for molybdenum oxide. Furthermore, in the case of molybdenum oxynitride or molybdenum tantalum oxynitride, the difference between the wet etching rate of the metal or alloy and the corresponding wet rate of oxynitride could be reduced.

Claims (11)

An optically transparent and electrically insulating substrate (1), at least one optically transparent and electrically conductive sensor element (2x, 2y) arranged on said substrate, and said optically transparent sensor element A touch sensor device (10) having at least one contact structure (4, 4') for electrical contact, said contact structure comprising the composition Mo _a X _b O _c N _d (where 0<b. ≦0.2 5a, 0.5≦c≦0.75, 0.01≦d≦0.2, a+b+c+d=1, and c+ d≦0.8 , and X is an element composed of niobium and tantalum. A touch sensor device comprising at least one layer made of a metal oxynitride having one or two elements selected from the group.). The touch sensor device of claim 1 in which the metal Okishinitori de or Ranaru layer having the composition Mo _a X _b O _c N _d is characterized by having a reflectivity of less than 20%. The composition Mo _a X _b O _c N metal Okishinitori de having _d is more than three times the nitrogen atoms, the touch sensor device according to claim 1 or 2, characterized in that it has a 9 times the oxygen atom. Wherein and contact structures are configured into a plurality layers, further, Al, Mo, Cu, according to claim 1 to 3, characterized in that it comprises a metal layer made of Ag or Au or an alloy based on one of these metals The touch sensor device according to claim 1. The sensor elements formed as sensor electrodes are arranged in a grid pattern, a plurality of first sensor elements are arranged at different positions in the first direction, and a plurality of second sensor elements are arranged as second electrodes. Said contact electrodes being arranged at different positions in a direction, each of said sensor electrodes being separated from each other by at least one electrically insulating layer at an intersection, said first plurality of sensor electrodes having a metal oxynitride at said intersection. the touch sensor device according to any one of claims 1 to 4, characterized in that in contact with the structure (4). According to any one of claims 1 to 4, characterized in that the contact structure (4 ') is formed as a contact terminal for electrically connecting the sensor element to the activation electronics or analysis electronics Touch sensor device. The touch sensor device according to any one of claims 1 to 6, characterized in that it is formed as a projection type capacitive touch sensor. A touch sensitive display unit having a touch sensor device according to any one of claim 1. 7 (touch panel), the touch sensor device is mounted upstream of the display unit (Autoseru) or integrated into the display unit (On-cell, in-cell) touch sensor display unit. The contact structure comprises at least one metal layer and at least one metal layerThe composition Mo _a X _b O _c N _d HaveMetal oxynitriDoA layer consisting ofComposition Mo _a X _b O _c N _d HaveMetal oxynitriDoThe layer comprising the metal layer is spaced apart from the display unit at a greater distance than the metal layer.8Touch sensor display unit according to. Claim 1-7 or the description of the touch sensor device sputtering target Mo _{1-z X} z for producing contact structures of _(here, X is one or selected from the following element group consisting of niobium and tantalum Two elements, 0<z≦0.2). A method for manufacturing a touch sensor device according to any one of claims 1 to 7 metal Okishinitori de or Ranaru layer having the composition Mo _a X _b O _c N _d is the supply of oxygen and nitrogen Below, a sputtering target Mo _1-z X _z (where X is one or two elements selected from the element group consisting of niobium and tantalum, and 0<z≦0.2). A method of manufacturing using a vapor deposition method.