JPH11125831A - Semiconductor device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the disconnection of electrode caused by a difference in level occurring in contact holes and to obtain stable connection between electrodes by packing a conductive material in contact hole regions including the upper electrodes connected to the lower electrodes. SOLUTION: A planarization film 12 is formed by applying a polyimide resin, acrylic resin, etc., over the entire surface. The contact holes 13 are opened in the planarization film 12 and a transparent conductive thin film of metals, such as Al, or ITO, etc., is deposited thereon so as to be electrically connected to the drain electrodes 11 and is patterned to a prescribed shape, by which the upper electrodes 14 are formed. Next, a conductive layer 15 is formed by a plating method or conductive resin film in the contact hole 13 parts. The constitution to electrically connect the upper electrodes 14 via the contact holes 13 to the drain electrodes 11 of TFTs of the device in such a manner, then to pack the recessed parts occurring in the contact holes 13 by the conductive layer 15 is adopted for the device and, therefore, the surface of the uppermost layer is made flat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device such as a thin film transistor used for an active matrix type liquid crystal display device and the like, and more particularly to an electrode structure for well connecting upper and lower electrodes via an insulating film. And a semiconductor device having the same.

[0002]

2. Description of the Related Art In recent years, semiconductor devices typified by ICs and LSIs, and electronic devices or home appliances incorporating these semiconductor devices have been developed and sold in large quantities on the market. Currently, not only TV receivers, V
TRs, personal computers, and the like are also widely spread and are no longer rare. Among them, a liquid crystal display device has attracted attention as a display having advantages of being thin, lightweight and low power consumption. In particular, an active matrix type liquid crystal display device in which a switching element such as a thin film transistor (hereinafter, referred to as a TFT) is provided for each pixel so as to control each pixel can provide excellent resolution and a clear image. It has been noted for reasons. Hereinafter, a TFT or an active matrix type liquid crystal display device will be described as a typical example of an electronic device incorporating a semiconductor element or a semiconductor device.

[0003] As a conventional active element, a TFT using an amorphous silicon thin film is known, and many active matrix type liquid crystal display devices equipped with the TFT are commercialized. At present, as an active element replacing the TFT using the amorphous silicon thin film, a pixel TFT for driving a pixel electrode and a TFT for driving the pixel are used.
There is a great expectation for a technique for forming a TFT using a polycrystalline silicon thin film, which has a possibility that a driving circuit for driving the TFT can be integrally formed on one substrate.

A polycrystalline silicon thin film has higher mobility than an amorphous silicon thin film used for a conventional TFT, and it is possible to form a high-performance TFT. If the driving circuit for driving the pixel driving TFT is integrally formed on one inexpensive glass substrate, the manufacturing cost will be significantly reduced as compared with the related art.

As a technique for forming a polycrystalline silicon thin film to be an active layer of such a polycrystalline silicon TFT on a glass substrate, there is a technique of depositing an amorphous silicon thin film on a glass substrate and then forming the amorphous silicon thin film at a temperature of about 600 ° C. A solid phase growth method that heats and crystallizes for a period of time to several tens of hours, or a laser crystallization method that irradiates a pulsed laser beam such as an excimer laser and immediately melts and recrystallizes the amorphous silicon thin film in that area. Such methods have been proposed.

In this active matrix type liquid crystal display device, an ITO (Indium Tin Ox) is applied to a pixel electrode.
There are a transmission type liquid crystal display device using a transparent conductive thin film such as (ide) and a reflection type liquid crystal display device using a reflection electrode such as a metal for a pixel electrode. Originally, a liquid crystal display device is not a self-luminous display, so in the case of a transmissive liquid crystal display device, an illumination device, a so-called backlight, is arranged behind the liquid crystal display device, and display is performed by light incident from there. It is carried out. In the case of a reflective liquid crystal display device, display is performed by reflecting external incident light by a reflective electrode.

In the case of a reflection type liquid crystal display device, power consumption is extremely small because a backlight is not used. However, there is a problem that display brightness and contrast are affected by use environment or use conditions, that is, ambient brightness. have.

On the other hand, in the case of a transmissive liquid crystal display device, since the display is performed using the backlight as described above, the power consumption is large, but the brightness is high without being greatly affected by the surrounding brightness. There is an advantage that display with contrast can be performed.

A pixel electrode made of a transparent conductive thin film such as ITO or a metal as described above is made of TF.
It is connected to the drain electrode of T, and is formed so as to have a certain distance therefrom so as not to short-circuit with the adjacent gate wiring or source wiring. In recent years, in order to enlarge the effective area of the pixel electrode, an interlayer insulating film 58 made of a polyimide resin or an acrylic resin is formed on the entire surface of the substrate 51 including the TFT as shown in FIG. The drain electrode 61 of the TFT and the pixel electrode 64 formed on the interlayer insulating film 58 through the opened contact hole 63
The pixel electrode structure on the protective film that connects to
(Referred to as an on-passive structure).

According to this method, the pixel electrode 64 is insulated from the gate wiring and the source wiring by the interlayer insulating film 58 made of a polyimide resin or an acrylic resin. It is possible to dispose the pixel electrode 64 over the wiring, thereby increasing the effective area of the pixel electrode 64, that is, the aperture ratio. Further, the interlayer insulating film 58 made of a polyimide resin or an acrylic resin can easily flatten a step caused by the TFT, the gate wiring, and the source wiring. Have.

However, in the above-described method, an interlayer insulating film 58 made of a polyimide resin or an acrylic resin is deposited to a thickness of 1 μm or more, for example, 2 μm to 4 μm in order to flatten a step caused by the TFT, the gate wiring, and the source wiring. Need to be done. Therefore, the step formed by the contact hole 63 opened to connect the pixel electrode 64 and the drain electrode 61 of the TFT becomes large, and the connection between the pixel electrode 64 and the drain electrode 61 of the TFT is often not performed well. Will occur.

By depositing an interlayer insulating film 58 made of resin, the step caused by the TFT, the gate wiring and the source wiring is reduced, but the contact hole 63 is formed.
Is also reflected on the surface of the pixel electrode 64, and a large step occurs in a part of the pixel electrode 64,
Therefore, there is also a problem that the alignment of the liquid crystal layer 70 is disturbed and the display quality is lowered.

Conventionally, as shown in FIG. 14, for example, as shown in Japanese Patent Application Laid-Open No. Hei 4-220625, the height of the contact hole 63 is substantially the same as the surface of the interlayer insulating film 58 made of resin. Conductor 7 such as metal
1 has been proposed. This manufacturing method is based on T
Conductor 7 made of metal or the like on drain electrode 61 of FT
1 is formed, an interlayer insulating film 58 for flattening a step such as a TFT is deposited, and then the interlayer insulating film 58 is etched so that the surface of the conductor 71 is exposed, and the pixel electrode 64 is connected. It is.

Further, Japanese Patent Publication No. 1-35351, JP-A-1-68727, or JP-A-4-30562.
As shown in Japanese Patent Application Laid-Open No. 7-107, the drain electrode 61 of the TFT
A manufacturing method has been proposed in which a conductor 71 such as plating is formed between the electrode and the pixel electrode 64, that is, in the contact hole 63 by an electrochemical method, and the pixel electrode 64 is connected thereto.

[0015]

The shape of the substrate surface as described above is a major factor that causes the alignment of the liquid crystal layer to be disturbed. This is because if the substrate surface has irregularities, the alignment of the liquid crystal layer is disturbed at that portion. Recently, as shown in FIG. 13 described above, a step due to a TFT, a gate wiring and a source wiring is reduced by the pixel-on-passive structure, and almost unevenness is present on the substrate surface when the flattening film is formed. Absent.

However, in order to form a pixel electrode thereafter, a step due to the thickness of the pixel electrode and a depression due to a contact hole for connecting the pixel electrode to the drain electrode of the TFT are formed. Although the step corresponding to the thickness of the pixel electrode is at most several thousand mm, the depression due to the contact hole is several μm, which is so large as to be incomparable with the step corresponding to the thickness of the pixel electrode.

In order to improve the connection between the drain electrode and the pixel electrode of the TFT, the contact hole may be formed into a tapered shape so as to have a slope. Accordingly, since the dimensions of the contact holes are also becoming finer, there is a situation in which extreme taper shape processing cannot be performed. That is, if the contact hole is formed into an extremely tapered shape, the dimension of the contact hole becomes large. If the size of the contact hole is increased, the step due to the contact hole is reflected on the surface of the pixel electrode as described above, and a large step occurs in a part of the pixel electrode, and the step causes the liquid crystal layer to be oriented. This is a major factor that causes display disturbance and lowers display quality.

In particular, this effect becomes remarkable when the size of the pixel electrode is minute. For example, if the size of the pixel electrode is 25
If the size of the contact hole is 5 μm square and the dimension of the contact hole is 5 μm square, the ratio of the contact hole to the area of the pixel electrode is 4%. However, a dimension shift due to etching is apt to occur in the step of opening the contact hole, and if the dimension of the contact hole becomes 10 μm square at the time of completion, the contact hole occupies up to 16%. Under such circumstances, it is not easy to eliminate the inconvenience caused by the step of the contact hole while maintaining a good connection between the drain electrode of the TFT and the pixel electrode.

The conventional method as described above has been proposed as a method for solving such a problem. In the conventional method disclosed in Japanese Patent Application Laid-Open No. Hei 4-220625, the TFT After forming a conductor made of metal or the like on the drain electrode, depositing a film for flattening a step such as a TFT, and then exposing the surface of the conductor,
A configuration in which a pixel electrode is connected to that portion is disclosed. Therefore, it is considered that the surface of the pixel electrode becomes flat, and the disorder of the orientation of the liquid crystal layer and the poor connection between the pixel electrode and the drain electrode of the TFT due to the step of the contact hole can be reduced.

However, according to this method, a conductor made of a columnar metal or the like having a thickness similar to the thickness of the interlayer insulating film made of a polyimide resin or an acrylic resin, that is, a thickness of 2 μm to 4 μm, is formed in the contact hole portion. Need to be formed. In order to form such a conductor, it is generally considered that a conductor is formed by a sputtering method or a plasma CVD method. At this time, since the film is thick, it takes a long time to form the film. It is conceivable that film peeling occurs during or after film formation. Further, even if the film formation is completed normally, it takes a longer time to etch and pattern it into a columnar shape, and such a method is not easy.

On the other hand, Japanese Patent Publication No. 1-35351, JP-A-1-68727 or JP-A-4-30562
In a conventional method disclosed in Japanese Patent Application Laid-Open No. 7-1995, a conductor is formed between a drain electrode of a TFT and a pixel electrode, that is, a contact hole portion by an electrochemical method such as plating, and a pixel is formed there. A configuration in which electrodes are connected is disclosed. According to these, the conductor connecting the drain electrode and the pixel electrode is formed in a self-aligned manner in the contact hole, so that a photolithography step for forming the conductor is unnecessary, and furthermore, the conductor is connected to the conductor. It is possible to eliminate the step due to the surface of the pixel electrode, especially the contact hole.

However, in this method, the adhesion between the conductor formed by an electrochemical method such as plating and the drain electrode is not always improved. Depending on the metal material forming the drain electrode, an oxide film or the like is easily formed on the surface. Generally, Al, Ti, and the like, which are widely used as electrodes and wiring materials of a TFT, correspond to this. If an oxide film or the like is formed on the surface of the metal material, not only a plating layer having a sufficient thickness cannot be obtained, but also good adhesion cannot be obtained.
Such a metal material requires complicated processes such as performing various surface treatments in advance, and requires considerable know-how.

When a plating layer is filled in a hole such as a contact hole, a situation may occur in which the surface of the insulating film in which the contact hole is opened does not always coincide with the surface of the plating layer. That is, FIG.
As shown in (b), a case where the surface of the plating layer 71 does not reach the position of the surface of the insulating film 58 or a case where the surface protrudes from the surface of the insulating film 58 may be considered. FIG.
(A) and (b) show the state in an enlarged manner. As in the pixel-on-passive structure described above, 2
When the plating layer 71 is to be filled in the contact hole 63 opened in the resin insulating film 58 having a film thickness of about μm, apart from the case where the plating layer 71 is formed very slowly, Considering the throughput, 1
If it is assumed that the plating layer 71 is formed in about a minute, the plating process time can be changed by only 10 seconds and 30 seconds.
The thickness of the resin insulating film 5 is increased or decreased by more than
In the worst case, taking into account the fact that the film thickness of
A concave portion or a convex portion of about μm or more is generated. In FIGS. 15A and 15B, the regions surrounded by circles indicate portions where a step has occurred due to the above-described reason. As a result, the initial 2 μm
Although the level difference is somewhat alleviated, the possibility of disconnection at the level difference is still completely eliminated in view of the film thickness (1000 to several thousand degrees) of the pixel electrode 64 and the like to be formed later. Remain without.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems. In a semiconductor device having a semiconductor element such as a thin film transistor arranged thereon, an upper electrode formed to be electrically connected to a lower electrode is provided. By filling the contact hole region opened in the insulating film containing a conductive material with a conductive material, it is possible to suppress disconnection of the electrode caused by a step due to the contact hole and obtain a stable connection between the electrodes. I have.

[0025]

According to a first aspect of the present invention, there is provided a semiconductor device comprising: a lower electrode; an insulating film formed on the lower electrode; and an insulating film formed on the insulating film. In a semiconductor device having an upper electrode connected to the lower electrode through a contact hole opened in a film, the contact hole region including the upper electrode connected to the lower electrode is filled with a conductive material. Thus, the above object is achieved.

In a semiconductor device according to a second aspect of the present invention, a conductive material and a conductive material are formed in the contact hole region including the upper electrode connected to the lower electrode. It is characterized by being filled with a substance which forms a flat surface, whereby the object is achieved.

At this time, the conductive material may be a metal thin film.

At this time, the conductive substance may be a resin film having conductivity.

Further, at this time, the substance forming the flat surface may be a conductive or insulating resin film.

According to a method of manufacturing a semiconductor device according to a sixth aspect of the present invention, a lower electrode, an insulating film formed on the lower electrode, an opening formed on the insulating film, and an opening formed in the insulating film. A method of manufacturing a semiconductor device having an upper electrode connected to the lower electrode through the contact hole formed, wherein the step of opening the contact hole in an insulating film formed on the lower electrode; Forming the upper electrode on an insulating film including: connecting the upper electrode and the lower electrode through the contact hole; and filling a conductive material in the contact hole region including the upper electrode. And a step of performing the above, whereby the above object is achieved.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: a lower electrode; an insulating film formed on the lower electrode; and an insulating film formed on the insulating film. A method of manufacturing a semiconductor device having an upper electrode connected to the lower electrode through a contact hole opened in the semiconductor device, wherein the step of opening the contact hole in an insulating film formed on the lower electrode; Forming the upper electrode on the insulating film including the contact hole, connecting the upper electrode and the lower electrode through the contact hole, and forming the insulating film in the contact hole region including the upper electrode. Forming a conductive material so as not to protrude beyond the surface of the upper electrode formed thereon, and forming the conductive material on the insulating film on the conductive material formed in the contact hole region. Forming a thin layer to the extent that the surface and substantially aligned with the upper electrode, are characterized by having a, by its, the above-mentioned object can be achieved.

At this time, the step of forming the conductive material includes:
It may be performed by a plating method.

At this time, the step of forming the conductive substance may be performed by applying a conductive resin.

As described above, according to the present invention, since the conductive material is filled in the contact hole region including the upper electrode connected to the lower electrode, particularly, the contact hole region where disconnection is easily caused is generated. Since the conductive substance is also filled in the portion near the bottom surface, disconnection of the upper electrode is prevented, and connection between the upper electrode and the lower electrode is ensured.

Further, since the contact hole region including the upper electrode connected to the lower electrode is filled with a conductive material and a material for forming a flat surface formed on the conductive material, A portion close to the bottom of the contact hole, which is a place where disconnection is likely to occur, is filled with a conductive material, which prevents disconnection of the upper electrode and ensures connection between the upper electrode and the lower electrode. . Further, since the conductive substance is filled with the substance which forms the flat surface, the surface flatness of the contact hole can be improved at the same time.

Further, by using a metal thin film as the conductive substance, it is possible to more reliably connect the upper electrode and the lower electrode.

Further, by using a conductive resin film as the conductive substance, it is possible to further improve the flatness between the upper electrode and the contact hole surface.

By using a conductive or insulating resin film as a substance for forming a flat surface,
In particular, a portion close to the bottom of the contact hole where disconnection easily occurs is filled with a conductive material to ensure good conduction, and the flatness of the surface of the upper electrode can be further improved, and the flat surface can be improved. When the material to be formed is made conductive, an electrode can be connected to that part, and when it is made to be insulating, other wiring can be easily provided in that part.

Further, by performing the step of forming the conductive substance by plating, it becomes possible to easily fill the contact hole region with a metal material having low resistance.

Further, by performing the step of forming the conductive substance by applying a resin having conductivity, the flatness of the surface of the upper electrode can be further improved.

[0041]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a TFT of the present invention, and FIG. 2 is a plan view thereof. FIG. 1 shows a cross section taken along the line AA 'in FIG.

T as an active element in the present invention
The FT has the following configuration as shown in FIG. A base coat film 2 made of an SiO ₂ film or the like is deposited on an insulating substrate 1 made of glass or the like, and an active layer 3 of a TFT made of a silicon thin film is formed on the base coat film 2 in a predetermined shape. The gate insulating film 4 is formed by depositing an insulating film such as a SiO ₂ film. On the active layer 3, a gate electrode 5 made of a metal material such as Al is formed in a predetermined shape with the gate insulating film 4 interposed therebetween.

Here, in the active layer 3, a source region and a drain region 6 into which impurity ions are implanted, and a channel region 7 into which impurity ions are not implanted in a region below the gate electrode 5, are formed. An insulating film is deposited on the entire surface to form an interlayer insulating film 8. A contact hole 9 is opened in the interlayer insulating film 8 and the gate insulating film 4 above the source region and the drain region 6.
A source electrode 10 and a drain electrode 11 made of a metal material such as
Connected to each other.

Thereafter, a flattening film 12 is formed by applying a polyimide resin, an acrylic resin or the like to the entire surface. And
A contact hole 13 is opened in the flattening film 12, and a metal such as Al or a transparent conductive thin film such as ITO is deposited so as to be electrically connected to the drain electrode 11,
The upper electrode 14 is formed by patterning into a predetermined shape.

Next, a conductive layer 15 is formed on the contact hole 13 by plating or a conductive resin film.

According to the present invention, the drain electrode 1 of the TFT
1 is electrically connected to the upper electrode 14 via the contact hole 13, and then the conductive layer 15 is used to fill the concave recessed portion caused by the contact hole. Therefore, the surface of the uppermost layer is flat. It has become something. Therefore, when the TFT according to the present invention is applied to a liquid crystal display device, unevenness that disturbs the alignment of liquid crystal molecules on the surface of the pixel electrode serving as the upper electrode 14 does not occur.

Further, according to the present invention, even if the drain electrode 11 and the upper electrode 14 of the TFT are disconnected in any part of the contact hole 13, the conductive layer 15 is formed in the contact hole 13. Therefore, it is possible to connect the disconnection points.

Further, in the present invention, when the conductive layer 15 is formed, a special coating apparatus is used when a conductive resin film is used, and a special equipment for a plating step is used when a plating method is used. No device or complicated pretreatment is required, and the steps other than the step of forming the conductive layer 15 are simplified by the film forming method and the etching method used for manufacturing the conventional active matrix type liquid crystal display device and TFT. It is possible to manufacture.

(Embodiment 1) Details of the manufacturing method according to Embodiment 1 of the present invention will be described below with reference to the drawings. 3 and 4 show TFTs according to the first embodiment.
FIG. 4 is a cross-sectional view showing a manufacturing process of the second embodiment.

As shown in FIG. 3A, a TFT is formed on an insulating substrate 1 such as a glass substrate by a known method. The creation method is generally as follows.

First, a base coat film 2 made of a SiO ₂ film or the like is deposited on a glass substrate 1 by a sputtering method or a plasma CVD method. Next, a polycrystalline silicon thin film, an amorphous silicon thin film, etc.
When the deposited film is an amorphous silicon thin film, the film is polycrystallized by irradiation with a laser beam from above. The polycrystallized silicon thin film is patterned into a predetermined shape to become the active layer 3 of the TFT.

Next, an insulating film such as a SiO ₂ film is deposited on the active layer 3 to form a gate insulating film 4.
A gate electrode 5 made of a metal material such as Al is formed in a predetermined shape with a gate insulating film 4 interposed therebetween.

Next, impurity ions are implanted into the active layer 3 using the gate electrode 5 as a mask, and thereafter a heat treatment for activating the implanted impurity ions is performed to form a source region and a drain region 6. At this time, a channel region 7 into which impurity ions have not been implanted is formed in a region below the gate electrode 5.

After that, an SiO ₂ or SiN _x film or the like is deposited on the entire surface to form an interlayer insulating film 8. Finally, an interlayer insulating film 8 located above the source region and the drain region 6
After opening a contact hole 9 in the gate insulating film 4, a source electrode 10 and a drain electrode 11 made of a metal material such as Al are formed, and the source electrode 10 and the drain electrode 11 are connected to the source region and the drain region 6. You. The TFT according to the first embodiment is manufactured in this manner.

In the first embodiment, a coplanar TFT using a polycrystalline silicon thin film for the active layer 3 has been described. However, an inverted staggered TFT using an amorphous silicon thin film for the active layer 3 may be used. . After this, the drain electrode 1
A cap electrode may be formed by depositing a metal film or a transparent conductive thin film of a material different from that of the drain electrode 11 on the first electrode 1 and patterning it into a predetermined shape. In this case, Ni, Cr, Cu, Fe, W, or the like can be used as the metal film.
TO, SnO ₂ or the like can be used.

Next, as shown in FIG. 3B, a flattening film 1 is formed by applying a polyimide resin or an acrylic resin on the entire surface.
Form 2 In the first embodiment, Optomer SS (manufactured by Nippon Synthetic Rubber Co., Ltd.) is used as the resin and is applied and formed on the substrate 1 so as to have a thickness of 2 μm to 4 μm, for example, 2 μm at the maximum.

Next, a contact hole 13 was opened in the planarizing film 12 located above the drain electrode 11. Dry etching using oxygen gas can be used for the opening of the contact hole 13. In the first embodiment, the oxygen gas flow rate is 400 sccm and the high-frequency power 600
Etching was performed under the conditions of W and a gas pressure of 20 mTorr to form a contact hole 13. The inner wall of the contact hole 13 was formed to be inclined at an angle of approximately 80 ° to 60 °. In addition, this contact hole 13
When the opening is formed, the diameter of the contact hole 13 on the side of the drain electrode 11 is made relatively small in consideration of the alignment accuracy so that the opening is reliably formed on the drain electrode 11. It is also desirable that the diameter of the hole be within a range not exceeding the outer dimensions of the drain electrode 11.
This is important in order to secure the connection between the electrodes and not to unnecessarily lower the aperture ratio when this TFT is used in a liquid crystal display device or the like. At this time, the flattening film 1
The resin used in 2 may be photosensitive.

Next, as shown in FIG. 4A, a transparent conductive thin film such as ITO or a metal film such as Al is formed so as to be electrically connected to the drain electrode 11 by a thickness of 1000 to several thousand.
For example, the upper electrode 14 is deposited to a thickness of about 2000 ° and patterned by using a photoresist mask to form the upper electrode 14 having a predetermined shape. At this time, as a method of depositing a transparent conductive thin film such as ITO or a metal film such as Al, a known method such as a sputtering method can be used.

Next, as shown in FIG. 4B, a mask made of a photoresist is formed, and a metal film is filled in a portion of the contact hole 13 by plating to form a conductive layer 15. Note that the photoresist is removed after the formation of the conductive layer 15.

The above plating method will be described below. Generally, the plating method often refers to an electrolytic plating method. In this method, a direct current is passed through an aqueous solution containing metal ions to be plated to obtain a metal film on a cathode surface. FIG. 12 shows this plating process. The equipment prepared in this step includes a plating solution 18, a plating tank 19 for containing the plating solution 18, and a DC power supply 20. In general, an electrode made of the same material as the metal to be plated is used for the anode 21. A nickel electrode is used for plating Ni, and a silver electrode is used for plating Ag.
Also, depending on the plating solution, some heating may be required. In that case, a heating equipment for the plating tank is prepared as an accessory equipment. The metals to be plated include Cu, A
g, Au, Cr, Fe, Ni, Pt and the like can be used. In the present invention, it is not particularly necessary to limit the metal to be plated, but it is preferable to determine it in consideration of compatibility with the underlying material as described later, and Ni, Cu, Ag, and the like are particularly promising. For example, Ni can be plated relatively easily, and is widely used for industrial purposes.
This is because u, Ag, and the like are considered to be suitable for use in electrodes and the like because of their sufficiently low electric resistance. As the aqueous solution, for example, in the case of Ni or Ag, nickel sulfate, nickel chloride, silver cyanide, or the like is used. In the first embodiment, plating is performed using Ag. The reason for selecting Ag is that, as described above, it is a material having a low electric resistance, and the price is much lower than that of a noble metal material having a low electric resistance.

The plating of the contact hole 13 in the first embodiment is performed, for example, by using Silbrex II (manufactured by Japan Electroplating Engineers) as a plating solution, at a current density of 1 A / dm ² and a plating solution temperature of 25. Plating was performed at about 2 minutes for about 2 minutes to form a conductive layer 15 of about 2 μm. The thickness of the conductive layer 15 can be determined by controlling the current density and time. The current density and the plating solution temperature may vary depending on the type of plating solution, and may be appropriately determined. In the first embodiment, the current density is 1 to 5 A / dm ² and the plating solution temperature is 20 to 3.
Conditions were set in the range of 0 ° C. Such a condition in the first embodiment is determined in consideration that when the area of a portion to be plated such as the contact hole 13 is small, it is easier to obtain a good result at a low current density. Things.

Next, steps before and after the plating step will be described. Prior to the plating step, the surface of the object to be plated is treated with hydrochloric acid or the like as necessary in addition to washing the surface with water. After the plating step, the substrate is washed with warm pure water at about 70 ° C. and dried. In the first embodiment, an example of plating of a single metal is shown, but plating of an alloy may be used.

In the first embodiment, the conductive layer 15 is formed after the upper electrode 14 electrically connected to the drain electrode 11 via the contact hole 13 is formed. Even when the surface of the upper electrode 14 projects or recedes from the surface of the upper electrode 14 to generate a step, the upper electrode 14 has no adverse effect such as disconnection.

Further, as shown in FIG. 5, since the flattening film 12 has a thickness of several μm, the contact hole 13 opened in the flattening film 12 also has a step of several μm. Will be. 10 for contact hole 13
The upper electrode 14 having a thickness of about 00 to several thousand is deposited and formed.
3 has a step of several μm, and its angle is also steep, so that it is difficult to deposit a film with a uniform thickness on the inner wall surface of the contact hole 13. In a region surrounded by a circle in FIG. In some cases, it was not possible to secure a sufficient film thickness and the wire was substantially disconnected. However, in the first embodiment, contact hole 13
By plating the portions, the contact holes 13 can be formed.
The conductive layer 15 deposited on the bottom of the contact hole 13 gradually grows as shown by the arrow in the figure and fills the contact hole 13, thereby making it possible to connect the broken portion of the upper electrode 14. It is.

Although not shown, after this, an alignment film is formed on the entire surface, and an alignment process is performed. Then, a counter substrate on which a color filter, a counter electrode, and the like are formed is attached.
A liquid crystal display device can be completed by injecting a liquid crystal between the substrates.

(Embodiment 2) Next, details of a manufacturing method according to another embodiment of the present invention will be described with reference to the drawings. 6 to 8 show TFTs according to the second embodiment.
FIG. 4 is a cross-sectional view showing a manufacturing process of the second embodiment.

As shown in FIG. 6A, after forming the TFT, a flattening film 12 made of resin is formed. Note that the manufacturing process of the TFT according to the second embodiment is the same as that of the first embodiment.
The description is omitted because it is the same as.

As shown in FIG. 6B, a contact hole 13 was opened in the planarizing film 12 made of resin. Dry etching using oxygen gas can be used for the opening of the contact hole 13. In the second embodiment,
First, oxygen gas flow rate 400 sccm, high frequency power 600
Etching was performed under the conditions of W and a gas pressure of 20 mTorr to form a contact hole 13. These steps are the same as in the first embodiment.

Next, as shown in FIG. 7A, a transparent conductive thin film such as ITO or a metal film such as Al is formed so as to be electrically connected to the drain electrode 11 by 1000 to several thousand.
For example, the upper electrode 14 is deposited to a thickness of about 2000 ° and patterned by using a photoresist mask to form the upper electrode 14 having a predetermined shape. At this time, as a method of depositing a transparent conductive thin film such as ITO or a metal film such as Al, a known method such as a sputtering method can be used.

Next, as shown in FIG. 7B, a metal film is filled in the contact hole 13 by plating to form a conductive layer 15. In the second embodiment, the conductive layer 1
5 is not completely filled in the contact hole 13 but is formed to have a thickness of about 1/3 to 2/3 from the bottom surface. An important point in this case is to prevent the conductive layer 15 from protruding from the surface of the upper electrode 14, and the thickness from the bottom surface may be appropriately determined. In the second embodiment, plating is performed using Ag, and for example, Silbrex II (manufactured by Japan Electroplating Engineers) is used as a plating solution. In addition, the thickness of the conductive layer 15 can be determined by controlling the current density and the processing time.
It was decided to control by the processing time. Specifically, current density 1
Plating was performed at A / dm ^{2 at} a plating solution temperature of 25 ° C. for about 1 minute to form a conductive layer 15 of about 1 μm.

The following description is the same as that described in the first embodiment, but will be repeated. The current density and the temperature of the plating solution may vary depending on the type of the plating solution, and may be appropriately determined. In the second embodiment, the conditions are set at a current density of 1 to 5 A / dm ² and a plating solution temperature of 20 to 30 ° C. Set. Such a condition in the second embodiment is determined in consideration that when the area of a portion to be plated such as the contact hole 13 is small, it is easier to obtain a good result at a low current density. Things.

Next, steps before and after the plating step will be described. Prior to the plating step, the surface of the object to be plated is treated with hydrochloric acid or the like as necessary in addition to washing the surface with water. After the plating step, the substrate is washed with warm pure water at about 70 ° C. and dried. In the second embodiment, an example of plating of a single metal is shown, but plating of an alloy may be used.

Next, as shown in FIG. 8A, a resin thin film layer 16 is deposited on the entire surface of the substrate. This resin thin film layer 16 is for filling the remaining portion of the contact hole 13 in which the conductive layer 15 is filled up to about 1/2. Here, it was applied and formed so as to have a thickness of about 1 μm. As a material to be used, Optomer SS (manufactured by Nippon Synthetic Rubber Co., Ltd.), which is the same material as the flattening film 12, was used. Alternatively, a colored or black resin material such as Color Mosaic CK (manufactured by Fuji Hunt) may be used. Further, the resin material used for the resin thin film layer 16 may be a conductive material or a photosensitive material.

Next, as shown in FIG. 8B, the entire surface of the resin thin film layer 16 is etched to expose the surface of the upper electrode 14. In this step, the entire surface is etched without using a mask such as a photoresist. This is called an etch back process. Dry etching with oxygen gas can be used for the etching. In the second embodiment, the oxygen gas flow rate is 400 sccm and the high frequency power 600
Etching was performed under the conditions of W and a gas pressure of 20 mTorr.

In the second embodiment, the contact hole 13 is filled with the conductive layer 15 to a position about 1/2 from the bottom surface, and the remaining portion is filled with the resin thin film layer 16. Therefore, the conductive layer 15 does not protrude from the surface of the upper electrode 14, and the remaining portion of the contact hole 13 is filled with the resin thin film layer 16, so that the surface of the upper electrode 14 becomes flat. ing. Further, when the resin thin film layer is insulative, other wiring can be provided in this portion. In this case, the surface is flat and there is no fear of disconnection. Further, when a TFT having such a structure is used in a liquid crystal display device, the surfaces of the electrodes including the electrodes are all flat, so that the alignment of the liquid crystal molecules is not adversely affected.

(Embodiment 3) Next, details of a manufacturing method according to another embodiment of the present invention will be described with reference to the drawings. 9 to 11 show TFs according to the third embodiment.
It is sectional drawing which showed the manufacturing process of T.

As shown in FIG. 9A, after forming the TFT, a flattening film 12 made of resin is formed. Note that the manufacturing process of the TFT according to the second embodiment is the same as that of the first embodiment.
The description is omitted because it is the same as.

As shown in FIG. 9B, a contact hole 13 was opened in the planarizing film 12 made of resin. Dry etching using oxygen gas can be used for the opening of the contact hole 13. In the second embodiment,
First, oxygen gas flow rate 400 sccm, high frequency power 600
Etching was performed under the conditions of W and a gas pressure of 20 mTorr to form a contact hole 13. These steps are the same as in the first embodiment.

Next, as shown in FIG. 10 (a), a transparent conductive thin film such as ITO or a metal film such as Al is electrically connected to the drain electrode 11 in a range of 1000 to several thousand Å, for example, 2000 Å. The upper electrode 14 having a predetermined shape is formed by patterning using a photoresist mask. At this time, as a method of depositing a transparent conductive thin film such as ITO or a metal film such as Al, a known method such as a sputtering method can be used.

Next, as shown in FIG. 10B, a conductive resin film 17 is applied over the entire surface to fill the contact hole 13 and to remove unnecessary conductive resin film 17 in the next step. I do. When an etch-back process is used as a removing method, it is preferable to apply the conductive resin film 17 to the surface of the conductive resin film 17 to such an extent that a concave depression due to the contact hole 13 does not occur. This is because the entire surface is uniformly etched in the etch back process. On the other hand, when the conductive resin film 17 has photosensitivity,
It may be applied to such an extent that the conductive resin film 17 is filled in the contact holes 13.

The conductive resin film 17 can be easily obtained by adding metal particles or carbon to a conventional insulating resin film. Alternatively, it can be obtained by mixing tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) into an insulating resin film. Conductive resin film 17 used in the third embodiment
Is not particularly limited to these, and may be appropriately determined, but it is preferable to select a material having as low an electric resistance as possible.

Next, as shown in FIG. 11, the unnecessary conductive resin film 17 deposited on portions other than the contact hole 13 is removed, and the conductive layer 15 is removed on the contact hole 13 portion.
To form Regarding the removal of the conductive resin film 17, unnecessary portions can be obtained by performing the etch-back step described in the second embodiment or exposing and developing using a mask when the conductive resin film 17 has photosensitivity. Can be removed. Note that the method for removing the resin film is not limited to these, and a method suitable for the used resin film may be appropriately employed.

In the third embodiment, since the conductive resin film is used as conductive layer 15, it is relatively easy to make the position of the surface of conductive layer 15 substantially coincide with the position of the surface of upper electrode 14. ing.

As described above, the TFTs manufactured in Embodiment Modes 1, 2, and 3 can be used as switching elements for driving pixel electrodes of a liquid crystal display device. This has the effect that the wire can be connected without breaking the wire or even if the wire is broken. Therefore, this structure is very effective for stabilizing the connection of electrodes and wirings having a contact between the upper and lower sides through a contact hole. This is not limited to a TFT, and is a semiconductor element having a structure for connecting the upper and lower electrodes. Alternatively, it can be widely applied to semiconductor devices.

[0085]

As described above, in the electrode connection structure of the present invention, it is possible to reliably connect an electrode or a wiring having a contact between the upper and lower sides through the contact hole.

Further, when a semiconductor element or a semiconductor device having such a connection structure between electrodes is applied to a liquid crystal display device, disconnection of a pixel electrode corresponding to an upper electrode can be prevented, and the semiconductor element can be used. The connection between the drain electrode and the pixel electrode of a certain TFT can be made more reliable, and the alignment disorder of the liquid crystal molecules due to the step of the contact hole does not occur, thereby obtaining a good display quality. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a TFT of the present invention.

FIG. 2 is a plan view showing a TFT of the present invention.

FIGS. 3A and 3B are cross-sectional views illustrating a manufacturing process of the TFT according to the first embodiment.

FIGS. 4A and 4B are cross-sectional views showing a manufacturing process of the TFT according to the first embodiment following FIGS. 3A and 3B.

FIG. 5 is a cross-sectional view showing details of an electrode connecting portion in the present embodiment.

FIGS. 6A and 6B are cross-sectional views illustrating a manufacturing process of the TFT according to the second embodiment.

FIGS. 7A and 7B are cross-sectional views showing a manufacturing process of the TFT according to the second embodiment following FIGS. 6A and 6B.

FIGS. 8A and 8B are cross-sectional views showing a manufacturing process of the TFT according to the second embodiment following FIGS. 7A and 7B.

FIGS. 9A and 9B are cross-sectional views showing the steps of manufacturing a TFT according to the third embodiment.

FIGS. 10A and 10B are cross-sectional views showing a manufacturing process of the TFT according to the third embodiment, following FIGS. 9A and 9B.

FIG. 11 is a cross-sectional view showing a manufacturing step of the TFT according to the third embodiment, following FIGS. 10 (a) and 10 (b).

FIG. 12 is a drawing showing a plating step in the first embodiment.

FIG. 13 is a cross-sectional view showing a semiconductor element having a pixel electrode structure on a protective film (pixel-on-passive structure).

FIG. 14 is a cross-sectional view showing a semiconductor device according to a conventional technique.

FIGS. 15A and 15B are cross-sectional views of a contact hole showing a conventional problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Base coat film 3 Active layer 4 Gate insulating film 5 Gate electrode 6 Source region and drain region 7 Channel region 8 Interlayer insulating film 9 Contact hole 10 Source electrode 11 Drain electrode (lower electrode) 12 Flattening film 13 Contact hole Reference Signs List 14 pixel electrode (upper electrode) 15 conductive layer 16 resin thin film layer 17 conductive resin film 18 plating solution 19 plating bath 20 DC power supply 21 anode 51 insulating substrate 58 interlayer insulating film 60 source electrode 61 drain electrode (lower electrode) 63 contact Hole 64 Pixel electrode (upper electrode) 70 Liquid crystal layer 71 Conductor

Claims (9)

[Claims] 1. A lower electrode, an insulating film formed on the lower electrode, and formed on the insulating film and connected to the lower electrode via a contact hole opened in the insulating film. A semiconductor device having an upper electrode, wherein the contact hole region including the upper electrode connected to the lower electrode is filled with a conductive material. 2. The contact hole region including an upper electrode connected to the lower electrode is filled with a conductive material and a material forming a flat surface formed on the conductive material. The semiconductor device according to claim 1, wherein: 3. The semiconductor device according to claim 1, wherein the conductive material is a metal thin film. 4. The semiconductor device according to claim 1, wherein the conductive material is a resin film having conductivity. 5. The semiconductor device according to claim 1, wherein the substance forming the flat surface is a conductive or insulating resin film. 6. A lower electrode, an insulating film formed on the lower electrode, and connected to the lower electrode via a contact hole formed on the insulating film and opened in the insulating film. Forming a contact hole in the insulating film formed on the lower electrode; forming the upper electrode on the insulating film including the contact hole; A step of connecting the upper electrode and the lower electrode via a contact hole; and a step of filling a conductive material in the contact hole region including the upper electrode. Production method. 7. A lower electrode, an insulating film formed on the lower electrode, and connected to the lower electrode via a contact hole formed on the insulating film and opened in the insulating film. Forming a contact hole in the insulating film formed on the lower electrode; forming the upper electrode on the insulating film including the contact hole; Connecting the upper electrode and the lower electrode through a contact hole; and conducting to the contact hole region including the upper electrode so as not to protrude from the surface of the upper electrode formed on the insulating film. Forming a conductive material, and forming a thin film layer on the conductive material formed in the contact hole region until the thin film layer substantially matches the surface of the upper electrode formed on the insulating film. The method of manufacturing a semiconductor device, characterized in that it comprises the steps of forming a. 8. The method according to claim 6, wherein the step of forming the conductive material is performed by a plating method. 9. The method of manufacturing a semiconductor device according to claim 6, wherein the step of forming the conductive material is performed by applying a conductive resin.