JP4501666B2 - Contact formation method - Google Patents

Description

The present invention relates to the formation how contacts.

Conventionally, in order to electrically connect a lower electrode formed on a substrate and an upper electrode formed on the lower wiring through an interlayer film, a contact hole is formed in the interlayer film, A technique for electrically connecting the upper electrode is known (for example, see Patent Document 1). In addition, the lower electrode has, for example, a laminated structure in which a cap metal layer is stacked on a conductive layer, thereby improving connectivity with a contact formed in the contact hole by the cap metal layer formed on the conductive layer. There is also technology to make it.
Generally, such a contact hole is formed by anisotropic etching by dry etching.

By the way, there is a technique for resonating and strengthening the light emitted from the light emitting layer by providing a resonator composed of different dielectric laminated films in the EL element. When such a resonator is provided, for example, between a drain electrode and a pixel electrode in an organic EL device, the drain electrode (first electrode) and the pixel electrode (second electrode) are connected via the resonator. It is necessary to let Therefore, a method of forming a contact hole in the resonator by using anisotropic etching as described above and conducting between these electrodes can be considered.
JP-A-9-2137798

However, since the resonator has a structure in which, for example, SiN layers and SiO ₂ layers, which are different dielectric layers, are alternately stacked, when a contact hole is formed by anisotropic etching, The etching rate differs with the SiO ₂ layer.
Thus, when the etching rate is different between the laminated structures, the amount of etching is higher in a dielectric layer having a higher etching rate, and the amount of etching is lower in a dielectric layer having a lower etching rate than the dielectric layer having a higher etching rate. It will decrease. Then, when the contact hole is formed in the resonator, unevenness is generated due to the difference in etching amount between the laminated structures, and an uneven portion is generated on the inner wall surface of the contact hole. As described above, when the uneven portion is formed on the inner wall surface of the contact hole, the contact formed in the contact hole may be disconnected by the uneven portion.
Therefore, when the contact hole is formed in the resonator, the etching rate of the SiN layer and the SiO ₂ layer is made substantially the same by performing strong etching so that a large selection ratio cannot be obtained with the drain electrode. It is conceivable to prevent the formation of uneven portions due to the difference in etching rate on the inner wall surface of the hole.

However, when strong etching is performed such that a large selection ratio cannot be obtained with the drain electrode as described above, even the cap metal layer of the drain electrode provided under the resonator is etched (overetching). . Thus, if the conductive layer is exposed by etching the cap metal layer of the drain electrode, for example, when the contact is formed by covering the inner wall surface of the contact hole with a conductive material, the conductive layer and the exposed conductive layer are electrically conductive. Contact resistance increases due to contact of the material, and sufficient connectivity cannot be obtained at the interface between the contact and the cap metal layer, and contact reliability is high and connection reliability cannot be obtained.
Thus, unless connection reliability at the conductive portion is obtained, the drain electrode and the pixel electrode cannot be satisfactorily conducted through the conductive portion, thereby reducing the yield.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a contact formation method and an organic EL device which are well connected to an over-etched drain electrode and have improved connection reliability and yield. To do.

  In order to solve the above-described problem, the contact forming method of the present invention is a method in which a contact hole is formed by etching in a resonator in which a plurality of different dielectric layers are stacked, and a first electrode provided below the resonator. And a second electrode provided on an upper layer of the resonator through a contact hole, wherein the conductive layer is formed on a substrate, and a cap metal layer is formed on the conductive layer. A step of forming the first electrode by laminating, a step of forming a resonator by laminating a plurality of different dielectric layers on the first electrode, and a contact hole by etching in the resonator. And a step of forming a contact for electrically connecting the first electrode and the second electrode by forming the second electrode, and the cap. The contact resistance between the tall layer and the second electrode is lower than the contact resistance between the conductive layer and the second electrode, and the cap metal layer has a thickness of 10% or more of the thickness of the resonator. It is characterized by forming in.

According to the contact forming method of the present invention, for example, when a contact hole is formed in the resonator by strong etching that does not allow a large selection ratio with the first electrode, the dielectric laminated film constituting the resonator The etching rate between them is substantially equal. Therefore, uneven portions due to the difference in etching amount are not formed on the inner wall surface of the contact hole.
However, if strong etching is performed such that a large selection ratio cannot be obtained with the first electrode, the contact hole penetrates the cap metal layer and reaches the conductive layer. As a result, the contact resistance between the conductive layer and the conductive material forming the contact increases, thereby reducing the connection reliability between the contact and the first electrode.
Therefore, if the present invention is adopted, since the cap metal layer having a thickness of 10% or more of the resonator is provided on the first electrode, the contact hole does not penetrate the cap metal layer. The conductive layer is prevented from being exposed.
Therefore, the contact becomes conductive with the conductive layer through the cap metal layer. Accordingly, this contact can satisfactorily connect the second electrode and the first electrode having the cap metal layer, thereby improving the connection reliability and the yield. In addition, since the concavo-convex portion due to the difference in etching rate is not formed on the inner wall surface of the contact hole, it is possible to prevent the contact from being disconnected due to the step of the concavo-convex portion.

  The resonator structure of the present invention is provided on a substrate, a first electrode, a resonator formed in a layer above the first electrode, a plurality of different dielectric layers being stacked, and a layer above the resonator. An organic EL device comprising a second electrode, an organic layer including a light emitting layer on at least the second electrode, and a third electrode provided on the organic layer, wherein the first electrode is electrically conductive And a cap metal layer provided on the conductive layer, and a contact hole provided in the resonator, and provided in the contact hole, for connecting the first electrode and the second electrode. A contact resistance between the cap metal layer and the second electrode is lower than a contact resistance between the conductive layer and the second electrode, and the cap metal layer has a thickness of the resonator. Has a thickness of 10% or more of the thickness And wherein the door.

According to the organic EL device of the present invention, even when a contact hole is formed in the resonator by strong etching that does not provide a large selection ratio with the first electrode, the resonator is formed on the first electrode. Since the cap metal layer having a thickness of 10% or more is provided, the contact hole does not penetrate the cap metal layer and reach the conductive layer. That is, since the contact hole formed by strong etching that makes the etching rate between the dielectric laminated films constituting the resonator substantially equal is provided, uneven portions due to the difference in etching amount are formed on the inner wall surface of the contact hole. Not formed. Therefore, the contact formed in the contact hole is prevented from being disconnected due to the uneven portion.
Further, since the contact resistance between the cap metal layer and the second electrode is lower than the contact resistance between the conductive layer and the second electrode, the first electrode is connected to the second electrode via the conductive layer. It will conduct well.
Therefore, the contact hole formed in the resonator is prevented from being disconnected by the uneven portion of the inner wall surface, and the contact having good conduction between the first electrode and the second electrode is provided. The EL device has high connection reliability between the first electrode and the second electrode, and has a high yield.

In the organic EL device, the first electrode is preferably a source electrode or a drain electrode of a thin film transistor formed on a substrate.
In this case, for example, when the first electrode is constituted by the drain electrode of the TFT and the second electrode is constituted by the pixel electrode, the drain electrode and the pixel electrode are reliably conducted through the contact formed in the resonator. be able to. Furthermore, since the TFT is used as the switching element, an EL device with more excellent display characteristics can be operated satisfactorily.

The contact forming method and the organic EL device of the present invention will be described below.
FIG. 1 is a side sectional view schematically showing an organic EL device having a resonator structure obtained by the contact forming method of the present invention. Here, an organic EL device using a thin film transistor as a switching element will be described.
In FIG. 1, reference numeral 1 denotes a resonator structure obtained by the contact forming method of the present invention, and reference numeral 100 denotes an organic EL device.
FIG. 2A is an enlarged view of a main part of the resonator structure 1. As shown in FIG. 2A, the resonator structure 1 includes the resonator 10 between a drain electrode (first electrode) 236 and a pixel electrode (second electrode) 141 of the organic EL device 100 described later. ing. The resonator 10 is formed with a tapered contact hole 20 that narrows its inner diameter toward the drain electrode 236 by etching, which will be described later. In the present embodiment, the contact 25 of the present invention is formed by filling a part of the pixel electrode 141 in the contact hole 20 and covering at least the inner wall surface of the contact hole 20.
In this embodiment, ITO (indium tin oxide), which is the material of the pixel electrode 141, is used as the conductive material for forming the contact 25. However, between the pixel electrode 141 and the drain electrode 236, the ITO is used. A conductive material having high conductivity may be used as appropriate so that a contact is formed and the pixel electrode 141 is electrically connected.
Based on such a configuration, the resonator structure 1 makes the drain electrode 236 and the pixel electrode 141 conductive through the contact 25.

(Cap metal layer)
FIG. 2B is a cross-sectional view of the drain electrode 236.
As shown in FIG. 2B, the drain electrode 236 of this embodiment has, for example, a three-layer structure. Specifically, a three-layer structure in which a titanium layer 236c is the lowest layer, an aluminum layer 236b is formed on the titanium layer 236c, and a titanium layer 236a serving as a cap metal layer is laminated on the aluminum layer 236b. It has become. Further, the titanium layer 236a serving as a cap metal layer has a thickness of 10% (58.5 nm) or more of the thickness (585 nm) of the resonator 10 described later. The aluminum layer 236b has high conductivity with the pixel electrode 141, and the titanium layer 236c provided under the aluminum layer 236b serves to prevent mutual diffusion between the aluminum layer 236b and the base material. It has become. The aluminum layer 236b and the titanium layer 236c constitute a conductive layer 237 in the drain electrode 236.
The titanium layer 236a formed on the conductive layer 237 (the uppermost layer of the drain electrode 236) prevents corrosion and hillocks on the aluminum layer 236b. Further, the contact resistance with the conductive material (pixel electrode 141) constituting the contact 25 is lower than the contact resistance between the conductive layer 237 and the drain electrode 236, and the connectivity between the drain electrode 236 and the contact 25 is improved. It is like that. The laminated structure constituting the drain electrode 236 may be molybdenum-aluminum-molybdenum.

(Resonator)
FIG. 3 is a diagram schematically showing the resonator 10. In FIG. 3, illustration of contact holes and contacts is omitted. As shown in FIG. 3, the resonator 10 has a structure in which dielectric laminated films are laminated. In the present embodiment, as the configuration of the dielectric laminated film, for example, from the drain electrode 236 side (see FIG. 2), the SiN layer 10a made of SiN having a thickness of 75 nm and the SiO ₂ layer 10b made of SiO _{2 having} a thickness of 120 nm are used. Is a resonator 10 having a layer thickness of 585 nm in which three pairs of dielectric laminated films having a film thickness of 195 nm are laminated.
The resonator 10 can enhance the emission spectrum of the light emitted from the organic EL device 100 due to the difference in refractive index between the SiO ₂ layer 10a and the SiN layer 10b.

(contact)
FIG. 4 is a diagram schematically showing the contact 25 formed in the contact hole 20 provided in the resonator 10. As shown in FIG. 4, the contact 25 is formed by covering the inner wall surface of the contact hole 20 with a conductive material (ITO) for constituting the pixel electrode 141 as described above. The contact hole 20 has a tapered shape that narrows the inner diameter toward the drain electrode 236.
Further, the contact hole 20 formed in the resonator 10 is strongly etched so that a large selection ratio cannot be obtained with the drain electrode 236 as will be described later (the etching rate of the drain electrode 236 and the etching of the resonator 10). By making the etching rate of the SiO ₂ layer 10a and the SiN layer 10b substantially the same, an uneven portion is not formed on the inner wall surface of the contact hole 20 due to the difference in etching amount. It has become. The contact hole 20 is formed in an over-etched state so as to reach the cap metal layer 236a formed in the drain electrode 236.
The boundary between the cap metal layer 236a and the pixel electrode 141 forming the contact 25 is smoothly connected along this tapered shape. As described above, the cap metal layer 236a has high adhesion to the pixel electrode (ITO) 141 forming the contact 25, and the contact 25 formed on the inner wall surface of the contact hole 20 has the cap metal layer 236a. Therefore, the drain electrode 236 is electrically connected to the drain electrode 236.

Returning to FIG. 1, the organic EL device 100 including the resonator structure 1 will be described.
As shown in FIG. 1, the driving TFT 143 includes a channel region through a source region 143a, a drain region 143b and a channel region 143c formed in the semiconductor film 210, and a gate insulating film 220 formed on the surface of the semiconductor layer. The gate electrode 143A opposed to 143c is mainly used. An interlayer insulating film 230 covering the semiconductor film 210 and the gate insulating film 220 is formed, and the cap metal layer 236a is provided in the contact holes 232 and 234 that penetrate the interlayer insulating film 230 and reach the semiconductor film 210, respectively. The drain electrode 236 and the source electrode 238 are buried, and each electrode is conductively connected to the drain region 143b and the source region 143a. In addition, since the source electrode 238 is formed by the same manufacturing process as the drain electrode 236, in this embodiment, the drain electrode 236 has a three-layer structure in which a cap metal layer 236a is provided as the uppermost layer.
The resonator 10 described above is formed on the interlayer insulating film 230 so as to cover the source electrode 238 and the drain electrode 236, and the contact 25 described above is formed on the inner wall surface of the contact hole 20 formed in the resonator 10. Is formed. That is, the organic EL device 100 of the present invention has a structure including the resonator 10 in place of a passivation film provided on an interlayer insulating film 230 of a general organic EL device.

  By providing the resonator structure 1 as described above, the pixel electrode 141 and the drain electrode 236 are conductively connected through the contact hole 20 formed in the resonator 10, so that the driving TFT 143 and the pixel electrode 141 ( Organic EL element 200) is electrically connected. An inorganic bank 149 made of an inorganic insulating material is formed so as to partially ride on the peripheral edge of the pixel electrode 141. On the inorganic bank 149, a bank 150 made of an organic material is stacked, and forms a partition member in the organic EL device 100.

  The organic EL element 200 is configured by stacking a hole injection layer (charge transport layer) 140A and a light emitting layer 140B on a pixel electrode 141 and forming a cathode 154 that covers the light emitting layer 140B and the bank 150. Has been.

In the case of a so-called top emission type organic EL device, the substrate P is configured to extract light from the side where the organic EL element 200 is disposed. Therefore, in addition to a transparent substrate such as glass, an opaque substrate can also be used. . Examples of opaque substrates include ceramics such as alumina, metal sheets such as stainless steel that have been subjected to insulation treatment such as surface oxidation, thermosetting resins and thermoplastic resins, and films thereof (plastic films). It is done.
The pixel electrode 141 is formed of a light-transmitting conductive material such as ITO (indium tin oxide) in the case of the bottom emission type that extracts light through the substrate P, but in the case of the top emission type, the light transmission is performed. It is not necessary to have a property, and it can be formed of an appropriate conductive material such as a metal material.

  The cathode 154 is formed on the substrate P in a state of covering the light emitting layer 140 </ b> B, the upper surface of the bank 150, and the wall surface forming the side surface of the bank 150. As a material for forming the cathode 154, in the case of the top emission type, a transparent conductive material is used. ITO is suitable as the transparent conductive material, but other translucent conductive materials may be used. A sealing portion (not shown) made of a protective film or the like is formed on the cathode 154, and a substrate (not shown) serving as a cover is formed on the sealing portion.

(Contact formation method)
Next, a method for forming the contact 25 will be described based on a method for manufacturing the organic EL device 100 including the resonator structure 1. In addition, the procedure and material structure shown below are examples, and are not limited thereto.
In the organic EL device 100 according to the present invention, both a configuration for extracting light from the organic EL element 200 from the substrate side (bottom emission) and a configuration for extracting light from the side opposite to the substrate P (top emission) can be adopted. The bottom mission type organic EL device 100 will be described.

  First, as shown in FIG. 5, the driving TFT 143 is formed on the substrate P. In the top emission type, since the substrate may be opaque, a ceramic sheet such as alumina, a metal sheet such as stainless steel that has been subjected to an insulation treatment such as surface oxidation, a thermosetting resin, a thermoplastic resin, or the like may be used. However, it may be a glass substrate conventionally used in a liquid crystal device or the like.

The manufacturing procedure of the driving TFT 143 is, for example, according to the following process.
First, a base protective film (not shown) made of a silicon oxide film having a thickness of about 200 to 500 nm is formed on the substrate P by plasma CVD using TEOS (tetraethoxysilane) or oxygen gas as a raw material as necessary. Keep it. Thereafter, the substrate temperature is set to about 350 ° C., an amorphous silicon film having a thickness of about 30 to 70 nm is formed on the surface of the substrate P by plasma CVD, and patterning is performed using a known photolithography technique, whereby the semiconductor film 210 is formed. Form. Then, the semiconductor film 210 is crystallized by being subjected to a crystallization process such as laser annealing or solid phase growth to form a polysilicon film. In the laser annealing method, for example, an excimer laser and a line beam having a beam length of 400 mm can be used, and its output intensity is, for example, 200 mJ / cm 2. With respect to the line beam, the line beam is scanned so that a portion corresponding to 90% of the peak value of the laser intensity in the short dimension direction overlaps each region.

  Next, a gate insulating film 220 made of a silicon oxide film or a nitride film having a thickness of about 60 to 150 nm is formed on the surface of the semiconductor film 210 and the substrate P by plasma CVD using TEOS or oxygen gas as a raw material. The semiconductor film 210 serves as a channel region and a source / drain region of the driving TFT 143, but semiconductor films serving as a channel region and a source / drain region of the switching TFT are also formed at different cross-sectional positions. .

  Next, after forming a metal film of aluminum, tantalum, molybdenum, titanium, tungsten, or the like, or a conductive film including a stacked film of these by sputtering or the like, the gate electrode 143A is formed by patterning. Subsequently, high concentration phosphorus ions are implanted into the semiconductor film 210 to form source / drain regions 143a and 143b in a self-aligned manner with respect to the gate electrode 143A. At this time, a channel region 143c is a portion which is shielded by the gate electrode 143A and no impurity is introduced.

Next, contact holes 232 and 234 penetrating the interlayer insulating film 230 are formed, and a drain electrode 236 and a source electrode 238 are formed in the contact holes 232 and 234 to obtain a driving TFT 143.
Here, when the drain electrode 236 and the source electrode 238 are formed, a titanium layer 236c, an aluminum layer 236b, and a titanium layer 236a to be a cap metal layer are sequentially stacked by, for example, a sputtering method. At this time, the titanium layer 236a is laminated on the aluminum layer 236b so as to be 10% (58.5 nm) or more of the thickness (585 nm) of the resonator 10. When the titanium layer 236a having a thickness of 10% or more is formed on the drain electrode 238 in this way, the drain is formed when etching is performed so as not to form an uneven portion on the inner wall surface of the contact hole 20 as will be described later. Since the titanium layer 238a having a sufficient thickness with respect to the amount of etching by this etching is formed on the electrode 238, the etching can be performed without the contact hole 20 reaching the conductive layer 237 of the drain electrode 238.
A conductive layer 237 of the drain electrode 236 is formed by the aluminum layer 236b and the titanium layer 236c.
Further, the titanium layer 236a formed on the conductive layer 237 (the uppermost layer of the drain electrode 236) prevents corrosion and hillocks of the aluminum layer 236b, and the conductive material (pixel electrode 141) constituting the contact 25. The adhesion between the drain electrode 236 and the contact 25 is improved.
Then, the drain electrode 236 and the source electrode 238 are formed by patterning using a known photolithography method or the like.

Next, as shown in FIG. 5, the resonator 10 made of a dielectric laminated film is formed on the interlayer insulating film 230 so as to cover the source electrode 238 and the drain electrode 236. In the figure, the resonator 10 is schematically shown.
In the resonator 10, a SiN layer 10 a made of SiN having a thickness of 75 nm is formed on the interlayer insulating film 230 as a lowermost layer by a CVD method or the like. Then, an SiO ₂ layer 10b made of SiO _{2 having a} thickness of 120 nm is formed on the SiN layer 10a in the same manner. Three pairs (a total of six layers) of 195 nm-thick dielectric layers, each paired with the SiO ₂ layer 10b and the SiN layer 10a, are sequentially stacked to form the resonator 585 nm.

(Formation of contacts)
Next, a method of forming the contact hole 20 in the resonator 10 and forming the contact 25 will be described with reference to FIGS.
After the resonator 10 is formed on the interlayer insulating film 230, the contact hole 20 is formed in the resonator 10 by etching.
In this embodiment, the contact hole 20 is formed by dry etching, for example, reactive ion etching (RIE) using CF ₄ 100 sccm, processing pressure 10 mT, and RF power 3 kW. Further, in the present embodiment, when the contact hole 20 is formed as described above, the inner diameter is narrowed toward the drain electrode 236 by adjusting the deposition rate and the etching rate of the sidewall protective film in the contact hole 20. A tapered contact hole 20 is formed.

At this time, when a selection ratio is obtained with respect to the drain electrode 236, specifically, an etching gas (for example, C ₄ F ₈ , CH ₂ F ₂ ) corresponding to an insulating layer such as the SiN layer 10a and the SiO ₂ layer 10b. by using, in the case of forming the contact hole 20 in the resonator 10, the material of the SiN layer 10a and the SiO ₂ layer 10b differences is to appear as a difference in etching rate. Then, between the SiN layer 10a and the SiO ₂ layer 10b, the SiN layer 10a having a high etching rate has a larger etching amount than the SiO ₂ layer 10b. Therefore, uneven portions due to such a difference in etching amount are formed on the inner wall surface of the contact hole 20.

Therefore, in the present invention, the contact hole 20 is formed in the resonator 10 by strong etching that does not provide a large selection ratio with the drain electrode 236.
At this time, for example, by making the etching strength corresponding to that of the drain electrode 236, the difference in the etching rate due to the material difference between the SiN layer 10a and the SiO ₂ layer 10b can be made small and substantially the same. it can. Therefore, by forming the contact hole 20 at the etching rate corresponding to the drain electrode 238 as described above, the etching amount between the SiN layer 10a and the SiO ₂ layer 10b constituting the resonator 10 can be made the same. The concave / convex portion due to the difference in etching amount between the SiN layer 10a and the SiO ₂ layer 10b is not formed on the inner wall surface of the contact hole 20.

Using such etching with a strength that does not allow the selection ratio between the drain electrode 236 and the resonator 10 to be formed, the tapered contact hole 20 is formed as shown in FIG. At this time, as described above, since the etching rates of the SiN layer 10a and the SiO ₂ layer 10b made of the insulating layer are substantially the same, the etching amounts of the SiN layer 10a and the SiO ₂ layer 10b are substantially the same, and the resonator In FIG. 10, a contact hole without an uneven portion is formed on the tapered surface. Therefore, as shown in FIG. 6B, a tapered contact hole 20 having no irregularities due to the difference in etching amount can be formed on the inner wall surface.

However, in the case of such strong etching, the contact hole 20 reaches the aluminum layer 236b through the cap metal layer 236a made of a titanium layer formed on the drain electrode 236. Here, as described above, the contact resistance between the cap metal layer 236a and the drain electrode 236 is lower than the contact resistance between the aluminum layer 236b constituting the conductive layer 237 and the drain electrode 236. Therefore, when the aluminum layer 236b is exposed in this manner, the contact resistance between the aluminum layer 236b and the pixel electrode 141 forming the contact 25 becomes high. Therefore, the connectivity between the pixel electrode 141 and the drain electrode 236 is lowered, and the connection reliability at these connection portions is lowered.
Therefore, if the present invention is adopted, the cap metal layer 236a having a thickness of 10% or more of the resonator 10 is formed on the drain electrode 236 as described above. Even if the contact hole 20 is formed by a strong etching that cannot take a selective ratio, the aluminum layer 236b of the drain electrode 236 can be prevented from being exposed by the cap metal layer 236a having a sufficient thickness.

Then, a contact material is deposited by depositing a conductive material by sputtering or vapor deposition, and covering the inner wall surface of the contact hole 20 with the conductive material. As described above, in the present embodiment, the contact 25 is formed by a part of the pixel electrode 141.
Therefore, by using a known photolithography technique or patterning technique, the contact 25 is formed by covering the inner wall surface of the contact hole 20 with a part of the pixel electrode 141 as shown in FIG.
At this time, since the titanium layer 236a serving as the cap metal layer has high adhesion to the pixel electrode 141 forming the contact 25, the contact 25 formed on the inner wall surface of the contact hole 20 passes through the cap metal layer 236a. Good conductivity can be obtained with the drain electrode 236 including the conductive layer 237. Further, since the inner wall surface of the contact hole 20 is tapered with respect to the cap metal layer 236a, the pixel electrode 141 that forms the contact 25 with the cap metal layer 236a follows the tapered shape. Connect smoothly.
Therefore, the pixel electrode 141 and the drain electrode 238 constituting the contact 25 are electrically connected, the connection reliability is improved, and the yield is high. In addition, since the strong etching as described above is used, an uneven portion is not formed on the inner wall surface of the contact hole 20, and disconnection of the pixel electrode 141 that becomes the contact 25 can be prevented by the step of the uneven portion.
Therefore, since the drain electrode 236 and the pixel electrode 141 are conducted through the contact 25, the connection reliability between these electrodes can be improved.
Through the above steps, the contact 25 can be formed in the contact hole 20 formed in the resonator 10, and the resonator structure 1 is obtained.

  Since the resonator structure 1 includes the contact 25 having high adhesion to the drain electrode 238 as described above and preventing disconnection due to the uneven portion of the inner wall surface of the contact hole 20 formed in the resonator 10. The resonator structure 1 including the contact 25 can improve the connection reliability between the drain electrode 238 and the pixel electrode 141.

The continuation of the method for forming the organic EL device 100 including the resonator structure 1 will be described with reference to FIGS.
As shown in FIG. 7A, the pixel electrode 141 is connected to the drain electrode 236 via the contact 25, and the pixel electrode 141 electrically connected to the drain region 143a of the driving TFT 143 via the drain electrode 236. Is formed.

  Prior to the formation of the pixel electrode 141, a process for cleaning the surface of the resonator 10 (for example, an oxygen plasma process, a UV irradiation process, an ozone process, etc.) may be performed. Thereby, the adhesion between the pixel electrode 141 and the resonator 10 can be improved.

Next, as shown in FIG. 7B, an inorganic bank 149 made of an inorganic insulating material such as silicon oxide is formed so as to partially overlap the peripheral portion of the pixel electrode 141 in a planar manner.
Specifically, after a silicon oxide film is formed so as to cover the pixel electrode 141 and the resonator 10, the silicon oxide film is patterned using a known photolithography technique to partially open the surface of the pixel electrode 141. Can be formed.

Next, as shown in FIG. 7C, a bank 150 made of an organic insulating material such as acrylic or polyimide is formed on the inorganic bank 149. The height of the bank 150 is set to about 1 to 2 μm, for example, and functions as a partition member for the organic EL element on the substrate P. With such a configuration, the hole injection layer and the light emitting layer of the organic EL element are formed, that is, an opening having a sufficiently high step between the application position of these forming materials and the surrounding bank 150. A portion 151 is formed.
Further, when forming the bank 150, it is preferable that the wall surface of the opening 151 of the bank 150 is slightly retracted outward from the opening 149b of the inorganic bank 149. In this way, by partially exposing the inorganic bank 149 in the opening 151 of the bank 150, the wetting and spreading of the liquid material in the bank 150 can be improved.

After the bank 150 is formed, a liquid repellent treatment is performed on the region on the substrate including the bank 150 and the pixel electrode 141. Since the bank 150 functions as a partition member for partitioning the organic EL element, the bank 150 preferably exhibits non-affinity (liquid repellency) with respect to the liquid material discharged from the droplet discharge head 20. By liquid treatment, non-affinity can be selectively expressed in the bank 150.
As such liquid repellent treatment, for example, a method of treating the surface of the bank with a fluorine compound or the like can be employed. Examples of the fluorine compound include CF ₄ , SF ₆ , and CHF ₃ , and examples of the surface treatment include plasma treatment and UV irradiation treatment.

  Next, as shown in FIG. 7C, a liquid material containing a hole injection layer forming material with the upper surface of the substrate P facing upward is applied to a coating position surrounded by the bank 150 by a droplet discharge method, for example. Apply selectively.

  As the hole injection layer forming material, polyphenylene vinylene whose polymer precursor is polytetrahydrothiophenylphenylene, 1,1-bis- (4-N, N-ditolylaminophenyl) cyclohexane, tris (8-hydroxyquinolinol) Aluminum, Vitron P, polystyrene sulfonic acid, etc. can be illustrated. Examples of the solvent include polar solvents such as isopropyl alcohol, N-methylpyrrolidone, and 1,3-dimethyl-imidazolinone.

  When the liquid material containing the above-described hole injection layer forming material is discharged onto the substrate P by the droplet discharge method, it tends to spread in the horizontal direction due to its high fluidity, but the bank 150 surrounds the applied position. Is formed so that the liquid material does not spread beyond the bank 150 to the outside thereof.

  Subsequently, the solvent of the liquid material 114 a is evaporated by heating or light irradiation to form a solid hole injection layer 140 A on the pixel electrode 141. Alternatively, firing may be performed at a predetermined temperature and time (for example, 200 ° C., 10 minutes) in an air environment or a nitrogen gas atmosphere. Or you may make it remove a solvent by arrange | positioning under the pressure environment (vacuum environment) lower than atmospheric pressure.

Subsequently, a liquid material containing a light emitting layer forming material and a solvent is discharged onto the hole injection layer 140A in the bank 150 with the upper surface of the substrate P facing upward, thereby forming the light emitting layer 140B. Thereby, the organic functional layer 140 composed of the hole injection layer 140A and the light emitting layer 140B is obtained. Then, the cathode 154 is formed on the organic functional layer 140 by using, for example, a vapor deposition method. The structures and film thicknesses of the resonator 10, the pixel electrode 141, the hole injection layer 140A, the light emitting layer 140B, and the cathode 154 described above are set so that the resonance effect is maximized. Further, a sealing portion (not shown) made of a protective film or the like is formed so as to cover the cathode 157, and a substrate (not shown) serving as a cover is formed on the sealing portion, thereby forming an organic EL. The apparatus 100 is completed.
Based on such a process, the organic EL device 100 including the resonator structure 1 can be obtained.
In the present embodiment, an EL device including an organic EL element has been described. However, the same applies to an EL device including an inorganic EL element including the resonator structure 1 of the present invention. In this embodiment, the contact hole 20 is tapered so that the inner diameter of the contact hole 20 is narrowed toward the drain electrode 236. However, the connection reliability is similarly applied when the contact hole 20 is not tapered. Contact with can be obtained.

  According to the organic EL device 100 of the present invention, the organic EL device 100 includes the resonator structure 1 having the contact 25 having a low contact resistance between the pixel electrode 141 and the drain electrode 236 and having connection reliability. It can be operated well. Moreover, since the resonator 10 is provided, the light emitted from the organic EL element 200 can be increased.

  So far, the case where a TFT is used as a switching element has been described. However, the present invention can also be applied to an organic EL device in which no TFT is used. 8A and 8B are diagrams showing another embodiment of the organic EL device of the present invention. In the embodiment using the TFT shown in FIG. 1, the drain electrode 236 of the TFT is used as the first electrode. However, in the embodiment shown in FIGS. 8A and 8B, the first electrode will be described later. It has an electrode or wiring structure in the passively driven organic EL device 100A.

  In such a passively driven organic EL device 100A, a plurality of striped pixel electrodes (anodes) 141 made of a transparent electrode material such as indium tin oxide (ITO) are formed in parallel with each other on the surface of a transparent substrate. Yes. An organic functional layer 140 is formed so as to cover the plurality of pixel electrodes 141. On the upper surface of the organic functional layer 140, a plurality of cathodes 154 made of a striped metal thin film are formed in parallel with each other. Accordingly, the organic functional layer 140 is sandwiched between the pixel electrode 141 and the cathode 154. The pixel electrode 141 and the cathode 154 are formed to be orthogonal to each other, and the organic functional layer 140 located at each intersection forms a pixel. Each stripe-shaped pixel electrode 141 is connected to a data electrode driver (not shown), and each stripe-like cathode 154 is connected to a scan electrode driver (not shown). . The data electrode driver and the scan electrode driver are controlled by a display controller. Based on such a configuration, the organic EL device 100A by passive drive can be driven.

FIG. 8A is a diagram illustrating a case where the first electrode connected to the pixel electrode 141 of the organic EL device 100A that is passively driven as described above is a single-layer wiring.
The organic EL device 100A of this embodiment, SiO ₂ layer 301 is provided on the glass substrate P. In addition, a wiring (first electrode) 300 connected to the data electrode driving unit is provided on the SiO ₂ layer. Further, on this wiring 300, there is provided a resonator 10A in which a SiN layer 10a is the lowest layer, and a laminated structure in which a pair of SiO ₂ layers 10b is laminated on this SiN layer 10a. In addition, in this resonator 10A, a contact for conducting the wiring 300 and the pixel electrode 141 through a contact hole is formed by the contact forming method of the present invention. Note that a cap metal layer (not shown) having a thickness of 10% or more of the resonator 10A is formed on the wiring 300.

An inorganic bank 149 is provided on the pixel electrode 141. Further, a bank 150 made of an organic material is laminated on the inorganic bank 149 to form a partition member in the organic EL device 100A.
The organic EL element 200 </ b> A is configured by stacking a hole injection layer (charge transport layer) 140 </ b> A and a light emitting layer 140 </ b> B on the pixel electrode 141 and forming a cathode 154 that covers the light emitting layer 140 </ b> B and the bank 150. Has been.

FIG. 8B is a diagram illustrating a case where the first electrode connected to the pixel electrode 141 of the organic EL device is a wiring having a two-layer structure. In FIG. 8B, the organic EL element 200A provided on the pixel electrode 141 is the same as the structure described in FIG. In the organic EL device 100B of the present embodiment, the SiO ₂ layer 301 is provided on the glass substrate P. Further, the resonator 10A is illustrated in a simplified manner.

A wiring (first electrode) 300 connected to the data electrode driving unit is provided on the SiO ₂ layer 301. A cap metal layer having a thickness of 10% or more of the resonator 10A is formed on the wiring 300. Then, on the SiO ₂ layer 301, an interlayer insulating film 230 for flattening the level difference is provided by the wire 300. On the interlayer insulating film 230, a conductive portion 302 connected to the wiring 300 through a contact hole is provided. That is, the first electrode of this embodiment has a two-layer structure including the wiring 300 and the conductive portion 302. Further, the resonator 10A is formed on the conductive portion 302. The contact is formed in the resonator 10A so that the pixel electrode 154 and the wiring 300 are electrically connected. A cap metal layer (not shown) having a thickness of 10% or more of the resonator 10A is formed on the conductive portion 302.

  Although not shown in FIG. 8B, an inorganic bank is provided on the pixel electrode 141 in the same manner as in the embodiment, and a bank made of an organic material is provided on the inorganic bank. Are stacked. An organic EL element is formed by providing a hole injection layer (charge transport layer) and a light emitting layer on the pixel electrode, and forming a cathode covering the light emitting layer and the bank. Based on such a configuration, the organic EL device 100A of the present embodiment can be driven.

  Also in this embodiment, the cap metal layer provided on the wiring 300 and the conductive portion 302 has a low contact resistance between the wiring 300 and the conductive portion 302 and the pixel electrode 141, and has a contact having a connection reliability. Therefore, the organic EL device 100A can operate satisfactorily.

Note that the organic EL devices 100 and 100A of the present invention may be used for a light emitting element of a line head, for example, as an exposure unit of an image forming apparatus of a line head printer. In this way, the organic EL devices 100 and 100A can operate accurately because the connection reliability between the pixel electrode 141 and the drain electrode 236 or the wiring 300 is high and the operation is favorable.
Further, since the organic EL devices 200 and 200A include the resonator 10, the light emitted from the organic EL elements 200 and 200A can be used efficiently, and the photosensitive drum of the image forming apparatus can be used efficiently. Exposure and high-definition printing can be obtained.
In addition, the organic EL devices 100 and 100A of the present invention may be used for a display unit of an electronic device such as a mobile phone. In this way, a good display can be obtained.

1 is a side sectional view showing an organic EL device of the present invention. (A) is a sectional side view of the resonator structure, (b) is a sectional side view of the drain electrode. The sectional side view which shows the structure of a resonator. The side sectional view showing a contact. The figure which shows the middle manufacturing process of the organic electroluminescent apparatus of this invention. (A)-(c) is process explanatory drawing of the formation method of the contact of this invention. (A)-(d) is process explanatory drawing of the manufacturing method of the organic electroluminescent apparatus of this invention. (A), (b) is a figure which shows other embodiment of the organic electroluminescent apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Resonator structure, 10 ... Resonator, 20 ... Contact hole, 25 ... Contact,
141 ... Pixel electrode (second electrode), 200 ... Organic EL device,
236 ... Drain electrode (first electrode), 236a ... Titanium layer (cap metal layer),
237 ... conductive layer

Claims (2)

Different dielectric layers Ri Na are stacked, the resonator for resonating the light emitting layer is emitted in the organic EL device, a contact hole is formed by etching, first provided in a lower layer of the resonator A method of forming a contact for electrically connecting an electrode and a second electrode provided in an upper layer of the resonator through the contact hole,
Forming a conductive layer on the substrate, having a thickness of 10% or more of the thickness of the resonator on the conductive layer, and having a contact resistance to the second electrode between the conductive layer and the second electrode; A step of forming the first electrode by laminating a cap metal layer lower than a contact resistance;
Forming the resonator by laminating a plurality of different dielectric layers on the surface of the cap metal layer above the first electrode;
Forming a contact hole in the resonator by performing etching so as to reduce a difference in etching rate due to a difference in material of the different dielectric layers;
By forming the second electrode, it viewed including the step of forming along a contact for conducting the said first electrode and said second electrode on the inner wall surface of the contact hole,
In the step of forming the contact hole, the contact hole is formed so as not to penetrate the cap metal layer .   The contact forming method according to claim 1, wherein in the step of forming the contact hole, the cap metal layer is over-etched.