JPH11298007A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device and a method of manufacturing thereof, in which device failures due to contact failure is reduced by electrically connecting a first material layer and a second material layer at a contact hole, and featuring a second material layer in the contact hole with comparatively higher density of group 12-15 elements as compared to other parts. SOLUTION: A first interlayer isolation film 114 is formed on an aluminum gate electrode 108 of a first materials layer, and an opening 301 is formed on it. A thin-metal film 215 is formed covering the opening 301 and the first interlayer isolation film 114. Next, a solution containing group 12-15 elements such as germanium is applied to the thin metallic film 215 to form a layer containing germanium. An alloyed material layer 220, formed by a film containing aluminum and the second material layer containing germanium, is formed by fluidizing the film containing germanium and the thin metallic film 215 at a temperature treatment. The alloyed material layer 220 assured the connection between the gate electrode 108 and the thin metal film 215.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD [0001] The invention disclosed in the present specification is:
The present invention relates to a semiconductor device having aluminum or an electrode or a wiring containing aluminum as a main component and a manufacturing method thereof.

[0002] In this specification, all devices that can function by utilizing semiconductor characteristics are called semiconductor devices. Therefore, the semiconductor device described in the claims includes not only a single element such as a TFT, but also a semiconductor circuit and an electro-optical device including a TFT, and an electric device having the components as components.

[0003]

2. Description of the Related Art Recently, a technique for manufacturing a thin film transistor (hereinafter referred to as a TFT) on an inexpensive glass substrate has been rapidly developed. The reason is that the demand for the active matrix type liquid crystal display device has increased.

An active matrix type liquid crystal display device is
TFTs (referred to as pixel TFTs) are arranged in each of millions of pixels arranged in a matrix, and electric charges entering and exiting each pixel electrode are controlled by a switching function of the TFTs.

[0005] In addition, T for driving the pixel TFT is used.
An integrated circuit in which an FT (referred to as a circuit TFT for convenience) is incorporated in a peripheral driving circuit, and a display pixel portion in which a pixel TFT is arranged and a driving circuit portion in which a circuit TFT is arranged is formed on the same substrate is considered. ing.

That is, such an integrated circuit is formed from millions of pixel TFTs and hundreds or more circuit TFTs. In such a configuration, of course, low production yield poses a problem.

For example, if one pixel TFT does not operate, the pixel electrode connected thereto loses its function as a display element. This causes a so-called point defect. For example, in the case of a normally black liquid crystal display device, a point defect is displayed as a black point when white is displayed, which greatly impairs the appearance.

If the circuit TFT does not operate, all the pixel TFTs to which the drive voltage is applied from the circuit TFT do not function as switching elements. This causes a so-called line defect, which is a fatal obstacle for the liquid crystal display device.

Therefore, in the active matrix type liquid crystal display device, it is necessary that millions of TFTs can maintain normal and stable operation for a long time. However, at present, it is extremely difficult to completely eliminate point defects and line defects.

The above-mentioned point defects and line defects are mainly caused by unnecessary operation of the TFT. One of the main causes of TFT malfunction is contact failure.

A contact failure occurs when an electrical connection (hereinafter referred to as a contact) between a wiring electrode and an active layer (formed of a thin film semiconductor layer) or a gate electrode of a TFT causes a connection failure. It is a malfunction. In particular, in the planar type TFT, since the wiring electrode and the TFT are electrically connected through a thin hole (contact hole), defective contact is a serious problem.

[0012] Contact failure is a main cause of early deterioration of semiconductor element characteristics, and the deterioration is particularly accelerated when a large current flows or in high-temperature operation. Therefore, it is said that the reliability of the contact determines the reliability of the semiconductor element.

Generally, in the case of a pixel display region in an active matrix type liquid crystal display device, the gate electrode is drawn out of the pixel display region as it is, so that there is only a contact with the active layer of the TFT.

In the case of a peripheral drive circuit, there are several hundred thousand to several million contacts. In particular, the presence of the contact of the gate electrode and the rise in temperature due to the large current operation mean that the contact is required to have reliability higher than that of the pixel display region.

There are roughly three causes of contact failure. One of the reasons is that the conductive film forming the wiring electrode and the semiconductor film forming the source / drain of the TFT are not in contact with each other through ohmic junction.

This is because an insulating film such as a metal oxide is formed on the joint surface. The state near the semiconductor film surface (impurity concentration, defect state density, cleanliness, etc.) greatly affects the performance of the contact.

The second cause is that the coverage of the conductive film forming the wiring electrode is poor and the wire is disconnected in the contact hole. In this case, it is necessary to improve by the film forming method and the film forming condition of the wiring electrode.

A third cause is a disconnection of a wiring electrode caused by a cross-sectional shape of a contact hole or the like. Cross-sectional shape of the contact hole is strongly dependent on the etching conditions of the insulator covered by the contact portion (SiN, SiO _2, etc.).

In particular, scouring and blowholes (nests) formed by over-etching are serious problems because coverage is significantly deteriorated. As an example,
The formation of scouring in the gate electrode will be described with reference to FIG.

FIG. 8 is an enlarged view of a contact hole portion for connecting a gate electrode of a planar type thin film transistor and a wiring.

In FIG. 8A, reference numeral 1101 denotes a gate electrode made of a metal material made of a material capable of being anodized, in this case, a material mainly containing Al (aluminum).
Note that a gate insulating film, a semiconductor layer, and the like are present below the gate electrode 1101, but are omitted for simplification of the drawing.

Reference numeral 1102 denotes an anodized film (mainly composed of Al ₂ O ₃ ) formed by anodizing the gate electrode 1101 in an electrolytic solution. The anodic oxide film 1102 is a very dense and strong film, and serves to protect the gate electrode 1101 from heat applied in the heat treatment step and to suppress generation of hillocks and whiskers.

Hillocks and whiskers are needle-like or barbed projections resulting from abnormal growth of aluminum.

Further, on the gate electrode 1102, 11
An interlayer insulating film indicated by 03 is formed. As the interlayer insulating film 1103, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or the like can be used.

Then, as shown in FIG. 8A, the interlayer insulating film 1103 is etched by a wet etching method or a dry etching method to form the contact hole 1.
104 is formed.

In order to form the contact hole 1104, the interlayer insulating film 103, which is a silicide film, must be etched first, and then the anodic oxide film 1102 must be etched.

However, since the anodic oxide film 1102 is a very dense and strong film, it takes time for etching. Therefore, when the isotropic etching is performed, the etching proceeds considerably in the lateral direction, and a scoured portion 1105 as shown in FIG. 8B is formed.

FIG. 8C shows a state where the wiring electrode 1106 is formed in this state. In such a case, FIG.
As shown in (C), the scorched portion 1105 is the wiring electrode 1
It cannot be covered with 106, which causes disconnection. Such a condition often causes a contact failure.

If the over-etching at the end of the etching of the anodic oxide film is long, the etching of the gate electrode 1101 progresses little by little, and a blow hole may be formed. This case also causes a contact failure.

In order to avoid the above problem, another metal material or a silicide material may be used as an electrode material. However, considering the characteristic of aluminum having a low resistance, such a measure is generally considered to be an effective measure. I can't say.

[0031]

SUMMARY OF THE INVENTION It is an object of the invention disclosed in this specification to solve the above-mentioned problems and to reduce the operation failure of a semiconductor device due to a contact failure.

It is an object of the present invention to provide a technique for eliminating a contact failure particularly when aluminum or a material mainly containing aluminum is used as an electrode.

Another object of the present invention is to improve the long-term reliability of a device using a semiconductor device or a liquid crystal display by improving the reliability of a contact. Another object is to eliminate a point defect or a line defect of a liquid crystal display device and to improve the yield of a manufacturing process.

[0034]

One of the structures of a semiconductor device disclosed in this specification for solving the above-mentioned problems is as follows: aluminum or a first material layer mainly containing aluminum; A semiconductor device comprising: an insulating layer formed on a material layer of, having an opening; and a second material layer containing aluminum or aluminum as a main component on the insulating layer, wherein the first material layer comprises The second material layer comprises:
Electrically connected through the opening, an element belonging to Group 12 to Group 15 is present in a higher concentration in a region of the second material layer existing in the opening than in other regions. A semiconductor device characterized by the following.

As the first material layer and the second material layer, aluminum or a material containing aluminum as a main component (for example, a wiring electrode, a lead wiring, or the like is formed) can be used.

In the present invention, when a material mainly containing aluminum is used, scandium, silicon,
It is preferable to contain a trace amount of copper or the like to suppress generation of hillocks and whiskers on the surface of the wiring material.

The first material layer and the second material layer may have a laminated structure or a structure in which another metal layer (for example, a titanium layer) is sandwiched between aluminum or a material containing aluminum as a main component. Ti / Al). Of course, tantalum, titanium,
It is possible to use a metal such as tungsten.

Another structure of a semiconductor device is a semiconductor device having a semiconductor layer, an insulating layer formed on the semiconductor layer and having openings, and aluminum or a material layer containing aluminum as a main component. And the semiconductor layer and the material layer are electrically connected through the opening,
In the region of the material layer present in the opening, 12-15
A semiconductor device in which an element belonging to a group exists at a higher concentration than other regions.

The semiconductor layer includes a semiconductor material having conductivity (for example, a source region and a drain region of a TFT are formed). Needless to say, silicide is also included in the semiconductor material having conductivity.

One of the structures of the method for manufacturing each semiconductor device of the present invention is a step of forming aluminum or a first material layer containing aluminum as a main component, and an insulating layer formed on the first material layer. Forming a hole in the insulating layer, exposing the first material layer at the bottom of the hole, and forming a second material layer containing aluminum or aluminum as a main component. Performing a step of applying a solution containing an element belonging to Group 12 to 15 in contact with the second material layer to form a layer containing the element; and applying a heat treatment to the second material layer. And a step of fluidizing the semiconductor device.

Further, in another configuration of the method of manufacturing each of the above semiconductor devices of the present invention, a step of forming a semiconductor layer, a step of forming an insulating layer on the semiconductor layer, and a step of forming an opening in the insulating layer And a step of exposing the semiconductor layer at the bottom of the opening, a step of forming a material layer mainly containing aluminum or aluminum, and including an element belonging to Group 12 to 15 in contact with the material layer. A method for manufacturing a semiconductor device, comprising a step of applying a solution to form a layer containing the element, and a step of performing heat treatment to fluidize the material layer.

The present invention is particularly applicable to aluminum (Al) or a wiring material containing aluminum as a main component.
A technique for lowering the fluidization temperature of the wiring material by adding an element belonging to Group 15 and fluidizing the wiring material by heat treatment to improve the coverage of the contact hole (referred to as a reflow technique). is there.

The elements belonging to groups 12 to 15 include:
In particular, one or more selected from germanium, tin, gallium, zinc, indium, and antimony are used. In addition, the said 12-15 group (former 2B-5B group)
Elements start with Zn in the element table and
An element ending with i.

In the present invention, a solution containing the elements belonging to Groups 12 to 15 is prepared using a solvent (such as water or an alcoholic solvent), and the solution is applied and dried to form a solution. A layer containing an element belonging to

Representative examples of the solution containing an element belonging to Group 12 to Group 15 include an aqueous solution of a compound selected from germanium oxide, germanium chloride, germanium bromide, germanium sulfide or germanium acetate.

In the present invention, when aluminum or a material containing aluminum as a main component is used,
The temperature of the step of bringing fluidity to the wiring electrode (reflow step) must be kept below 450 ° C. in consideration of the heat resistance of aluminum.

Examples of the element which brings fluidity to the wiring electrode at a temperature of 450 ° C. or less include the above-mentioned elements belonging to Groups 12 to 15, such as germanium, tin, gallium, zinc, lead, indium, and antimony. Can be

In the above structure, a so-called alloy is formed by subjecting a solution layer mainly composed of germanium formed in the contact hole and a laminated film composed of a thin film mainly composed of aluminum to heat treatment. Form a layer. Of course, this alloy layer easily shows fluidity by a reflow process at a temperature of 450 ° C. or less. At this time, the concentration of the germanium element in the alloy layer is 20 to 40, considering that the content of germanium having an eutectic point is 30 atomic%.
It is desirable to have a concentration of atomic%.

The heating means used in the reflow step may be any of means for heating with an electric furnace or means for irradiating strong light such as ultraviolet light or infrared light. For example, a technique called RTA (rapid thermal annealing) is known as a heating means using strong light.

In this specification, a method for manufacturing a planar type TFT will be described. However, the present invention can be implemented regardless of the TFT structure. That is, the TFT structure is not limited to the structure shown in FIGS.
The present invention can be easily applied to a structure having a T or silicide structure as required by a practitioner.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS For example, in the structure shown in FIG. 2, when a wiring 217 made of aluminum is brought into contact with a gate electrode 108 made of aluminum, first, as shown in FIG. The insulating film is selectively etched to form a gate contact hole.
After that, as shown in FIG.
5 is formed, and a solution containing germanium is applied thereon and dried to form a germanium layer 200. Then, a heat treatment (reflow step) is performed.

By the above reflow process, as shown in FIG. 2C, a mixed layer 220 of aluminum and germanium is formed. By forming the mixed layer 220, a broken portion (a scorched portion or the like) of a wiring made of aluminum is filled and a good contact is formed.

[0053]

[Embodiment 1] This embodiment relates to a manufacturing process of a thin film transistor, and shows an example in which a reflow process is performed using a metal material containing aluminum as a main component as a wiring electrode. The thin film transistor (TF
FIGS. 1 and 2 show examples of the manufacturing process of T).

First, as shown in FIG. 1A, a glass substrate 101 having an insulating surface is prepared, and silicon oxynitride (indicated by SiO _x N _y ) 102 serving as a base film is formed to a thickness of 200 nm.
Was formed to a thickness of

As the substrate, a material having high heat resistance, such as a quartz substrate, a crystallized glass, a ceramic substrate, a silicon substrate, etc. can be used in addition to a glass substrate. In an integrated circuit having a multilayer structure, a suitable insulating film can be used as a base. A base film may be formed on the substrate as needed. Note that a silicon oxide film or a silicon nitride film can be used as the base film.

An amorphous silicon film (not shown) having a thickness of 50 nm was formed thereon by a plasma CVD method or a low pressure thermal CVD method, and crystallized by an appropriate crystallization method. This crystallization may be caused by heating or irradiation of laser light. In addition, a method of adding an element (for example, Ni) that promotes crystallization during crystallization (typically, Japanese Patent Application No. 8-214,197).
-335152). In addition, a method of adding germanium during crystallization may be used.

Next, the crystalline silicon film obtained by crystallizing the amorphous silicon film was patterned to form an island-shaped semiconductor layer 103 constituting an active layer.

On top of this, a silicon oxide film 104 which later functions as a gate insulating film was formed to a thickness of 150 nm. The silicon oxide film 104 may be formed by a plasma CVD method or a low pressure thermal CVD method. Note that a silicon oxynitride film or a silicon nitride film can also be used. Further, these may be combined to form a laminated structure.

Next, a metal thin film 105 made of aluminum or a material containing aluminum as a main component was formed to a thickness of 400 nm. This aluminum film 105 is to form the gate electrode 108 later. Of course, it is also possible to use a material that can be anodized, such as tantalum or niobium, in addition to aluminum.

Next, the aluminum film 105 is placed in an electrolytic solution.
Was used as an anode to perform anodic oxidation. As the electrolytic solution,
A 3% tartaric acid solution in ethylene glycol was neutralized with aqueous ammonia to adjust the pH to 6.92. The treatment was performed using platinum as a cathode under the conditions of a formation current of 5 mA and a reaching voltage of 10 V. As a result, a dense anodic oxide film (not shown) was formed on the surface of the aluminum film 105. The thickness of the anodic oxide film having this dense film quality can be controlled by controlling the voltage application time. This dense anodic oxide film has the effect of increasing the adhesion between the next photoresist to be formed and the aluminum film 105. (Fig. 1 (A))

When the structure shown in FIG. 1A was obtained, a resist mask (not shown) was arranged and the aluminum film 105 was patterned. Then, an aluminum pattern (not shown) constituting the gate electrode 108 and the anodic oxide films 106 and 107 was formed later.

Next, a second anodic oxidation was performed to form a porous anodic oxide film 106. The electrolytic solution was a 3% oxalic acid aqueous solution, and the above aluminum pattern was used as an anode, platinum was used as a cathode, and a formation current was 2-3 mA, and a treatment voltage was 8 V. At this time, the anodic oxidation proceeds in a direction parallel to the substrate. This is because a resist mask (not shown) exists on the upper surface, where anodic oxidation does not proceed. Here, the length of the porous anodic oxide film 106 is controlled by controlling the voltage application time. In this embodiment,
The thickness of the anodic oxide film 106 was set to 0.7 μm.

Further, after the resist mask was removed with a dedicated stripper, a third anodic oxidation was performed to obtain the state shown in FIG. 1 (B). At this time, the electrolytic solution was prepared by neutralizing an ethylene glycol solution of tartaric acid of 3% with ammonia water, and PH = 6.
The one adjusted to 92 was used. Then, the treatment was performed using platinum as a cathode at a formation current of 5 to 6 mA and an ultimate voltage of 100 V. The anodic oxide film 107 formed at this time is very dense and strong. Therefore, it has an effect of protecting the gate electrode 208 from damage caused in a later step such as a doping step and heat from a heating step. In this anodic oxidation step, since the electrolytic solution penetrated into the porous anodic oxide film 106, the anodic oxide film 107 was formed around the aluminum pattern. In FIG. 1B, the aluminum pattern remaining without being anodized substantially becomes the gate electrode 108.

Next, impurities were implanted into the island-shaped semiconductor layer 103 by an ion doping method or a plasma doping method. In this case, P (phosphorus) was used as an impurity in order to manufacture an N-channel TFT. In the case of forming a P-channel TFT, B (boron) is used.

First, the first ion doping was performed in the state shown in FIG. The implantation of P (phosphorus) is performed at an acceleration voltage of 60 to 90 kV and a dose of 0.2 to 5 × 10 ¹⁵ atoms / c.
carried out in m ^2. In this embodiment, ion doping was performed at an acceleration voltage of 80 kV and a dose of 1 × 10 ¹⁵ atoms / cm ² . Then, the gate electrode 108 and the porous anodic oxide film 106 serve as a mask, and regions 109 and 110 which will later become the source / drain are formed in a self-aligned manner. (Figure 1
(See (C))

Next, as shown in FIG. 1C, the porous anodic oxide film 106 was removed, and the second doping was performed. The second injection of P (phosphorus) is performed at an acceleration voltage of 60.
The operation is performed at 90 kV and a dose of 0.1-5 × 10 ¹⁴ atoms / cm ² . In this embodiment, the accelerating voltage is 80 kV and the dose is 1 ×
It was 10 ¹⁴ atoms / cm ² . Then, the gate electrode 108
Serve as a mask, and the source region 109 and the drain region 11
Low-concentration impurity region 11 having a lower impurity concentration than 0
1, 112 are formed in a self-aligned manner.

At the same time, since no impurity is implanted directly below the gate electrode 108, the region 113 functioning as a channel of the TFT is defined in a self-aligned manner. Further, an offset region (not shown) to which a gate voltage is not applied is formed by an amount corresponding to the thickness of the anodic oxide film 107.

The low-concentration impurity region 112 has an effect of suppressing the formation of a high electric field between the channel region 113 and the drain region 110. This region is generally L
It is called a DD (lightly doped drain) region.

Next, laser annealing by irradiation with KrF excimer laser light and thermal annealing are performed. In this embodiment, the energy density of the laser light is 250 to 300 mJ / cm ^2.
The thermal annealing was performed at 300 to 450 ° C. (1 hour). By this annealing step, the crystallinity of the island-shaped semiconductor layer 103 damaged in the ion doping step can be improved.

Next, as shown in FIG. 1D, a first interlayer insulating film 114 made of a silicon oxynitride film is
Formed by Method D. This interlayer insulating film 114 may be a silicon oxide film or a silicon nitride film. Further, a multilayer structure of these insulating films may be used.

Next, as shown in FIG. 2A, a contact hole (opening) for electrically connecting the source electrode and the gate electrode to the TFT is formed. In this embodiment, this contact hole is formed by a wet etching method using buffered hydrofluoric acid. The formation of the contact hole (opening) may be performed by a dry etching method.

At this time, openings for the source contact portion and the gate contact portion were simultaneously formed. That is, the formation of the contact hole for the semiconductor layer and the formation of the contact hole for the gate electrode are performed simultaneously. This method is a desirable means for reducing the number of times of patterning and simplifying the process.

First, in the source contact portion, the first interlayer insulating film 114 and the gate insulating film 104 are etched in this order, so that the source region 109 of the island-shaped semiconductor layer 103 is exposed. In this state, the etching is still in progress because the etching rate of the anodic oxide film 107 is low in the gate contact portion.

When the anodic oxide film 107 is etched with a hydrofluoric acid-based etchant, the etching proceeds non-uniformly.
8 also proceeds at the same time.

Therefore, when the etching of the anodic oxide film 107 is completed, over-etching proceeds in the source contact hole portion, the gate electrode 108 is eroded in the gate contact hole portion, and the respective contact hole portions are etched as shown in FIG. A scrambled portion as shown in A) is formed.

Such a state is inevitably generated, although it is a matter of degree, and has been a major cause of contact failure.

Next, a metal thin film 215 covering the contact hole and the first interlayer insulating film is formed by a sputtering method.
The film is formed to a thickness of 400 nm. In this embodiment, the metal thin film 215 is used.
An aluminum film obtained by adding 0.2 wt% of scandium to aluminum was used. The reason why scandium is added is to suppress generation of hillocks and whiskers due to abnormal growth of aluminum. Instead of scandium, silicon or copper may be used.

In the state after the above-mentioned steps, since the undercut portion and the blow hole cannot be completely covered, there is a high possibility that the wire is disconnected in the contact hole. At this time,
A state in which attention is paid only to the contact hole provided above the gate electrode 108 will be described with reference to FIG.

FIG. 3 shows a cross-sectional shape of a contact hole 301 provided in the interlayer insulating film 114 formed on the gate electrode 108. In the contact hole 301, a germanium layer 200 and a metal thin film 215 are formed. ing. That is, the gate electrode 108 in FIG.
This corresponds to an enlarged sectional view of the upper contact hole.

In the state after the above steps, there is a high possibility that the metal thin film 215 is disconnected at the bottom of the contact hole 301 due to poor coverage as shown in FIG. 3A (within a circle indicated by 302).

In the sputtering method, contact holes 3
It is difficult to form a thick film on the side wall of the substrate 01, and it is often extremely thinner than a desired film thickness (in a circle indicated by 303).

At the entrance of the contact hole 301, the deposited metal thin film 215 protrudes (within a circle indicated by 304), and in some cases, comes into contact with it to close the entrance of the opening, so that the inside of the contact hole is closed. A nest (cusp) may be formed.

Therefore, in this embodiment, after the step of forming the metal film 215, a solution containing germanium is applied to cover the metal film to form a layer containing germanium.
It is characterized by performing a reflow process.

Examples of such a solution include germanium oxide (GeO _x , typically GeO ₂ ), germanium chloride (G
aqueous solution of eCl ₄ ), germanium bromide (GeBr ₄ ), germanium sulfide (GeS ₂ ), and germanium acetate (Ge (CH ₃ CO ₂ )).

In some cases, an alcoholic solvent such as ethanol or isopropyl alcohol may be used as the solvent.

In this embodiment, a layer 200 containing germanium was formed on the metal film 215 by preparing a 10 to 100 ppm aqueous solution of germanium oxide, applying the solution on the metal film 215, and spin-drying. Preferably, the spin drying is performed without contacting oxygen.

At this time, the germanium oxide aqueous solution easily accumulates inside the contact hole, and the germanium-containing layer 200 can be formed even at poor coverage (in the circle indicated by 302) at the bottom of the contact hole. (FIG. 3 (A))

The reflow step is a step for fluidizing the metal thin film 215 by heating to secure the contact between the gate electrode 108 made of aluminum and the metal thin film 215 made of aluminum. This reflow step needs to be performed at a temperature in the range of 375 to 450 ° C. in consideration of the heat resistance of the gate electrode 108 made of aluminum. Is increasing).

In this embodiment, the temperature was set at 450 ° C. in an electric furnace.
Heat treatment was performed for one hour. At this time, the processing atmosphere may be a vacuum, an inert atmosphere such as nitrogen, or a hydrogen atmosphere.

By this heat treatment, first, a reaction occurs at the interface between the germanium layer 200 and the metal thin film 215, and an alloy layer 220 having a composition of aluminum, scandium, and germanium is formed.

This reaction proceeds gradually due to the diffusion of germanium and aluminum, and has a composition containing germanium. For this reason, it becomes fluid at a temperature of 400 ° C., and the reflow process proceeds.

By the reflow process, the vicinity of the interface between the metal thin film 215 and the germanium layer 200 has fluidity and covers the scorched portions and the gaps of the blow holes without breaking. Therefore, all the disconnection portions or contact failure portions of the metal thin film 215 are short-circuited, and the gate electrode 10
8 (or the source region 109).

FIG. 3B is an enlarged sectional view of the contact hole after the completion of the reflow step. The metal thin film 215 temporarily having fluidity by the reflow process covers the disconnection location or the poor contact location and fills the inside of the contact hole. The inside of the contact hole becomes the alloy layer 220, and in a region other than the contact hole, the metal thin film 215 remains below the alloy layer 220 although not shown. Therefore, in the inside of the contact hole (particularly, the region where the alloy layer 220 is in contact with the side wall and the bottom of the contact hole), the germanium element exists at a higher concentration than the region other than the contact hole.

Although the eutectic point of aluminum and germanium is at least 424 ° C., the above-mentioned fluidization of germanium can be performed even at about 400 ° C. However, it is preferable to perform the heating at a temperature of 375 ° C. or more in the reflow step from the viewpoint of reproducibility of the effect. The upper limit is preferably set to 450 ° C. or less in consideration of the heat resistance of aluminum.

After the above steps, the alloy layer 220 is patterned to form a source electrode 216 and a gate electrode 217. In addition, the above-mentioned process order is appropriately changed, for example,
After forming the source electrode 216 and the gate electrode 217,
The step of performing the reflow step may be performed.

Next, a second interlayer insulating film 218 is formed. In this embodiment, first, the source electrode 216 and the gate electrode 21 are formed of a silicon nitride film or a silicon oxynitride film (not shown).
7 covered. This corresponds to a buffer film for forming a resin material with good adhesion.

A material made of a resin was laminated thereon as the second interlayer insulating film 218. Since this resin material can be selected to have a lower dielectric constant than silicon oxide or silicon nitride, it is possible to reduce the influence of the capacitance formed between the transparent electrode formed later and the TFT.

Since the resin material used for the second interlayer insulating film 218 is excellent in flattening the upper surface of the device, it is necessary to apply a uniform voltage to the liquid crystal (not shown) from the transparent electrode. Can be.

Finally, a transparent electrode 219 made of ITO was formed to produce a thin film transistor (TFT) arranged in a pixel region of an active matrix type liquid crystal display device as shown in FIG. Thus, an active matrix substrate was completed. Thereafter, by sandwiching a liquid crystal layer between the counter substrate and a known substrate by a known cell assembling process, an AMLCD as shown in FIG. 6 is completed.

TFT manufactured according to the steps of this embodiment
Shows good contact irrespective of the shape of the contact hole, so there is no possibility of a problem such as a malfunction of the TFT due to disconnection of a wiring or an electrode.

[Embodiment 2] In this embodiment, an example in which a different means is employed as the method for forming a germanium layer in Embodiment 1 will be described.

In the first embodiment, since the solution containing germanium is applied directly on the metal film, a natural oxide film may be formed on the surface of the metal thin film. In particular, aluminum oxide may inhibit fluidization in a later reflow step. Therefore, in this embodiment, a germanium thin film is continuously formed after forming the metal thin film, preferably without opening to the atmosphere, and then a solution containing germanium is applied on the germanium thin film in a nitrogen atmosphere.

This prevents the formation of a natural oxide film on the surface of the metal thin film which hinders fluidization in the subsequent reflow step, and prevents poor coverage at the bottom of the contact hole which cannot be covered by continuous film formation. , A solution containing germanium could be present.

Thereafter, a reflow process is performed to cover the disconnection location or the poor contact location with an alloy layer of germanium and aluminum to fill the inside of the contact hole. Thus, the germanium element inside the contact hole was present at a higher concentration than in the region other than the contact hole.

After the alloy layer is obtained as described above, the active matrix substrate is completed according to the steps of the first embodiment.

[Embodiment 3] In the above Embodiments 1 and 2, the example of the top gate type TFT is shown.
A configuration using T may be used. Figure 6 shows the bottom gate type T
1 shows an example of the structure of an FT. 601 is a substrate, 602 is a base film, 603 is a gate electrode, 604 is a gate insulating film, 6
05 is a source region, 606 is a drain region, and 607 is L
DD region, 608 is a channel formation region, 609 is a channel protective film, 610 is an interlayer insulating film, 611 is a source electrode, and 612 is a drain electrode. The source electrode 611 and the drain electrode 612 are manufactured in the same manner as in the first and second embodiments using the reflow process disclosed in the present invention.

[Embodiment 4] An example in which an AMLCD is formed using an active matrix substrate (element formation side substrate) including the configuration shown in Embodiments 1 to 3 will be described. Here, the appearance of the AMLCD of this embodiment is shown in FIG.

In FIG. 6A, reference numeral 801 denotes an active matrix substrate on which a pixel matrix circuit 802, a source driver 803, and a gate driver 804 are formed. It is preferable that the drive circuit be formed of a CMOS circuit in which an N-type TFT and a P-type TFT are complementarily combined. Reference numeral 805 denotes a counter substrate.

In the AMLCD shown in FIG. 6A, an active matrix substrate 801 and a counter substrate 805 are bonded together with their end faces aligned. However, only a part of the counter substrate 805 is removed, and an FPC (flexible print circuit) 806 is connected to the exposed active matrix substrate. The FPC 806 transmits an external signal to the inside of the circuit.

Further, IC chips 807 and 808 are attached using the surface on which the FPC 806 is attached.
These IC chips are configured by forming various circuits such as a video signal processing circuit, a timing pulse generating circuit, a gamma correction circuit, a memory circuit, and an arithmetic circuit on a silicon substrate. In FIG. 6A, two are attached, but one or more may be attached.

Also, a configuration as shown in FIG. 6B can be adopted.
6B, the same parts as those in FIG. 6A are denoted by the same reference numerals. Here, FIG. 6A illustrates an example in which signal processing performed by an IC chip is performed by a logic circuit 809 formed using TFTs over the same substrate.
In this case, the logic circuit 809 also includes the drive circuits 803 and 80
As in the case of No. 4, a CMOS circuit is basically used.

The AMLCD of this embodiment has a structure in which a black mask is provided on an active matrix substrate (BM0).
n TFT), but a black mask may be provided on the opposite side in addition to the TFT.

Color display may be performed using a color filter, or the liquid crystal may be driven in an ECB (electric field control birefringence) mode, a GH (guest host) mode, or the like.
It is good also as composition not using a color filter.

[Embodiment 5] The construction of the present invention is similar to that of the AMLC
In addition to D, the present invention can be applied to various other electro-optical devices and semiconductor circuits.

An electro-optical device other than AMLCD is E
Examples include an L (electroluminescence) display device and an image sensor.

The semiconductor circuit includes an arithmetic processing circuit such as a microprocessor constituted by an IC chip, and a high-frequency module (MMIC) for handling input / output signals of a portable device.
Etc.).

FIG. 5 shows an example of a microprocessor. The microprocessor typically includes a CPU core 11, a flash memory 12 (or a RAM), a clock controller 13, a cache memory 14, a cache controller 15, and a serial interface 1.
6, an I / O port 17 and the like.

Of course, the microprocessor shown in FIG. 5 is a simplified example, and an actual microprocessor is designed for various circuits depending on the application.

In the microprocessor shown in FIG.
Core 11, clock controller 13, cache controller 15, serial interface 16, I / O
The port 17 is constituted by a CMOS circuit 18 having an SOI structure. The CMOS circuit 18 is provided with a wiring electrode 20 using the reflow process disclosed in the present invention. As a method for manufacturing the CMOS circuit 18 shown in FIG. 5, a method using a SIMOX substrate, an ELTRA
An SOI substrate using an N method, a smart cut method, or the like is used. In this embodiment, a CMOS circuit 18 was manufactured by forming a silicon gate 19 using a SIMOX substrate.

As described above, the present invention can be applied to all semiconductor devices functioning with circuits constituted by insulated gate transistors.

[Embodiment 6] The AMLCD shown in Embodiment 4
Are used as displays of various electronic devices.
Note that an electronic device described in this embodiment is defined as a product equipped with an active matrix liquid crystal display device.

Examples of such electronic devices include a video camera, a still camera, a projector, a projection TV, a head mounted display, a car navigation, a personal computer (including a notebook type), a portable information terminal (a mobile computer, a mobile phone, and the like). Is mentioned. One example is shown in FIG.

FIG. 7A shows a mobile computer (mobile computer), which includes a main body 2001 and a camera section 2.
002, an image receiving unit 2003, operation switches 2004, and a display device 2005. The present invention is applied to an image receiving unit 200.
3. Applicable to the display device 2005 and the like.

FIG. 7B shows a head mounted display, which comprises a main body 2101, a display device 2102, and a band 2
103. The present invention can be applied to the display device 2102.

FIG. 7C shows a mobile phone, which is a main body 220.
1, audio output unit 2202, audio input unit 2203, display device 2204, operation switch 2205, antenna 2206
It consists of. The present invention can be applied to the audio output unit 2202, the audio input unit 2203, the display device 2204, and the like.

FIG. 7D shows a video camera,
301, display device 2302, audio input unit 2303, operation switch 2304, battery 2305, image receiving unit 230
6. The present invention can be applied to the display device 2302, the sound input unit 2303, and the image receiving unit 2306.

FIG. 7E shows a rear type projector, which includes a main body 2401, a light source 2402, a display device 2403,
Polarizing beam splitter 2404, reflector 240
5, 2406 and a screen 2407. The invention can be applied to the display device 2403.

FIG. 7F shows a front type projector, which includes a main body 2501, a light source 2502, and a display device 250.
3. It comprises an optical system 2504 and a screen 2505. The invention can be applied to the display device 2503.

As described above, the applicable range of the present invention is extremely wide, and can be applied to electronic devices in all fields. In addition, the present invention can be used for an electronic bulletin board, a display for advertising, and the like.

[0130]

When a contact is formed on a wiring electrode containing aluminum as a main component, a solution containing an element belonging to Groups 12 to 15, typically, such as germanium or tin, is applied and a reflow process is performed. Thereby, a reliable contact can be formed by the action of the element.

As a result, it is possible to make good contact even in the case where an undercut portion or a blow hole is formed in the contact hole, and it is possible to greatly improve the reliability of the TFT.

[Brief description of the drawings]

FIG. 1 is a diagram showing a manufacturing process of a TFT of Example 1.

FIG. 2 is a view showing a manufacturing process of the TFT of Example 1.

FIG. 3 is a diagram illustrating a manufacturing process of the TFT of Example 1, and is an explanatory diagram of a reflow process.

FIG. 4 is a diagram in which the present invention is applied to a bottom gate type TFT (Example 3).

FIG. 5 is a diagram in which the present invention is applied to a semiconductor circuit (Embodiment 5).

FIG. 6 is a diagram showing a configuration of an AMLCD device.

FIG. 7 illustrates a semiconductor device as an applied product.

FIG. 8 is an enlarged sectional view of a conventional contact hole.

[Explanation of symbols]

 Reference Signs List 101 substrate 102 base film 103 island-shaped semiconductor layer 104 gate insulating film 105 metal thin film 106 porous anodic oxide film 107 dense anodic oxide film 108 gate electrode 109 source region 110 drain region 111 low concentration impurity region 112 low concentration impurity region 113 Channel formation region 114 First interlayer insulating film 200 Solution layer made of elements belonging to groups 12 to 15 215 Metal thin film 216 Source electrode 217 Drain electrode 218 Second interlayer insulating film 219 Transparent electrode 220 Alloy layer 301 Contact hole (open Hole)

Claims (7)

[Claims] A first material layer containing aluminum or aluminum as a main component; an insulating layer formed on the first material layer and having openings; and aluminum or aluminum as a main component on the insulating layer. A second material layer, wherein the first material layer and the second material layer are electrically connected through the opening,
In the region of the second material layer present in the aperture, 12
A semiconductor device in which an element belonging to Groups 15 to 15 is present at a higher concentration than other regions. 2. A semiconductor layer, formed on the semiconductor layer,
A semiconductor device comprising: an insulating layer having an opening; and aluminum or a material layer containing aluminum as a main component, wherein the semiconductor layer and the material layer are electrically connected to each other through the opening. A semiconductor device, wherein an element belonging to Group 12 to 15 is present at a higher concentration in a region of the material layer existing in the hole than in other regions. 3. The method according to claim 1, wherein
A semiconductor device, wherein the element belonging to Group 2 to 15 is one or more elements selected from germanium, tin, gallium, zinc, indium, and antimony. 4. A step of forming a first material layer containing aluminum or aluminum as a main component, a step of forming an insulating layer on the first material layer, and forming an opening in the insulating layer. Exposing the first material layer at the bottom of the opening, forming aluminum or a second material layer containing aluminum as a main component, and contacting the second material layer with 12 to 15 A step of applying a solution containing an element belonging to group III to form a layer containing the element, and applying a heat treatment to fluidize the second material layer. Production method. 5. A step of forming a semiconductor layer, a step of forming an insulating layer on the semiconductor layer, a step of forming an opening in the insulating layer, and exposing the semiconductor layer at a bottom of the opening. Forming a material layer containing aluminum or aluminum as a main component;
A step of applying a solution containing an element belonging to Groups 2 to 15 to form a layer containing the element; and performing a heat treatment to fluidize the material layer. Production method. 6. The method according to claim 4, wherein
A method for manufacturing a semiconductor device, wherein the element belonging to Groups 2 to 15 is one or more elements selected from germanium, tin, gallium, zinc, indium, and antimony. 7. The solution according to claim 4, wherein the solution containing an element belonging to Groups 12 to 15 is a compound selected from germanium oxide, germanium chloride, germanium bromide, germanium sulfide, and germanium acetate. A method for manufacturing a semiconductor device, characterized by being an aqueous solution of: