JP2003163355A - Thin-film semiconductor device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture thin-film semiconductor devices and electronic apparatuses that have good characteristics stably by a realistic and simple means. <P>SOLUTION: For the material of interconnections, tantalum of the alpha structure containing hydrogen is used. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film semiconductor device adapted to an active matrix liquid crystal display and the like, a manufacturing method thereof, an electronic device having electric wiring formed on an insulating material, and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, with the increase in screen size and resolution of liquid crystal displays (LCDs), the drive system has changed from a simple matrix system to an active matrix system,
It is becoming possible to display a large amount of information. The active matrix method enables a liquid crystal display having more than several hundred thousand pixels, and forms a switching transistor for each pixel. As a substrate for various liquid crystal displays, a transparent insulating substrate such as a fused silica plate or glass that enables a transmissive display is used. A semiconductor film such as amorphous silicon or polycrystalline silicon is usually used as an active layer of a thin film transistor (TFT), but polycrystalline silicon, which has a high operating speed, is advantageous when a thin film transistor is to be integrated with a driving circuit. Is. When a polycrystalline silicon film is used as an active layer, a fused silica plate is used as a substrate, and a TFT is usually manufactured by a manufacturing method called a high temperature process in which the maximum process temperature exceeds 1000 ° C. On the other hand, when an amorphous silicon film is used as an active layer, a normal glass substrate is used. In order to expand the display screen of the LCD and reduce the price, it is essential to use inexpensive ordinary glass as the insulating substrate. However, as described above, the amorphous silicon film has a problem that the electrical characteristics are significantly inferior to the polycrystalline silicon film and the operation speed is slow. Further, since the polycrystalline silicon TFT in the high temperature process uses the fused quartz plate, there is a problem that it is difficult to increase the size and cost of the LCD. After all, there is a strong demand for a technique for producing a thin film semiconductor device having a semiconductor film such as a polycrystalline silicon film as an active layer on a normal glass substrate. However, when using a large-sized ordinary glass substrate that is highly mass-producible, there is a great restriction that the maximum process temperature is about 570 ° C. or less in order to avoid substrate deformation. That is, there is a demand for a technique of forming a thin film transistor capable of operating a liquid crystal display under such restrictions and an active layer of the thin film transistor capable of operating a driving circuit at high speed. These are currently referred to as low temperature process poly-Si TFTs.

Conventional low temperature process poly-Si TF
T is SID (Society for Information)
Diction P.t. Three
87 (1993). According to it, first, by the LPCVD method, monosilane (Si
H ₄ ) is used to deposit a 50 nm amorphous silicon (a-Si) film at a deposition temperature of 550 ° C.
The film is irradiated with laser and the a-Si film is poly-Si.
Reform into a film. After patterning the poly-Si film,
A SiO ₂ film, which is a gate insulating film, is deposited by ECR-PECVD at a substrate temperature of 100 ° C. After forming a gate electrode with tantalum (Ta) on the gate insulating film, donor or acceptor impurities are ion-implanted into the silicon film using the gate electrode as a mask to make the source / drain of the transistor self-aligned (self-aligned). Form.
At this time, ion implantation uses a mass non-separation type implanter called an ion doping method, and phosphine (PH ₃ ) or diborane (B ₂ H ₆ ) diluted with hydrogen is used as a source gas. Activation of implanted ions is at 300 ° C. After that, an interlayer insulating film is deposited, and indium tin oxide (IT
The thin film semiconductor device is completed by forming electrodes and wiring with O) or aluminum (Al).

[0004]

However, the following problems are inherent in the low temperature process poly-Si TFT according to the above-mentioned prior art, and these are obstacles to mass production. That is, Problem 1). The resistance value of the conductor material used for the gate electrode and the scanning wiring is high. Therefore, the waveform of the scanning signal becomes dull, which prevents the normal operation of the switching TFT provided in each pixel. That is, the liquid crystal display (LCD) cannot be made finer or larger.

Problem 2). When making a self-aligned TFT (S / A TFT) in which the source / drain regions are self-aligned with the gate electrode by the ion implantation method,
The gate electrode is required to have a blocking ability that prevents implanted ions from entering the semiconductor film which will be the channel region and the gate insulating film provided immediately above the semiconductor film. However, if the gate electrode is made of metal, the implanted ions pass through the metal crystal lattice with a certain probability and end up. That is, the ion blocking ability of the gate electrode is inferior, and stable production of S / A TFTs cannot be performed.

Problem 3). In an electronic device with long wiring, which is represented by a large LCD, disconnection is likely to occur due to internal stress of the wiring material and thermal expansion and contraction due to temperature change. This situation is S /
This becomes more serious when it is necessary to overcome the step difference (step difference of the semiconductor film in the case of the S / ATFT) of the wiring like the scanning line of the ATFT. For this reason, there arises a problem that the manufacturing yield of electronic devices is significantly reduced.

Therefore, the present invention aims to solve the above-mentioned various problems, and an object thereof is to provide a method for stably manufacturing a good thin film semiconductor device or an electronic device by a practical and simple means. .

[0008]

According to the present invention, a semiconductor layer is formed on an insulating material in an island shape, a gate insulating layer is formed on the semiconductor layer, and a gate is formed on the gate insulating layer. A thin film semiconductor device including an electrode is characterized in that at least a part of the gate electrode is hydrogen-containing α-structure tantalum.

Further, the present invention comprises a semiconductor layer formed in an island shape on an insulating material, a gate insulating layer formed on the semiconductor layer, and a gate electrode formed on the gate insulating layer. A thin film semiconductor device is characterized in that the gate electrode is tantalum containing nitrogen and hydrogen.

The present invention also provides a method of manufacturing a thin film semiconductor device formed on an insulating material, wherein a thin film containing tantalum as a main component is formed by a sputter deposition method in an atmosphere containing at least hydrogen, nitrogen and argon. It is characterized by including a step of forming.

Further, the present invention is a method for manufacturing a thin film semiconductor device including a lower conductive layer and a conductive layer composed of an upper conductive layer whose main component is α-structure tantalum, in which the lower conductive layer is formed. It is characterized by including a first step and a second step of forming a thin film containing α-structure tantalum as a main component by a sputter deposition method in an atmosphere containing at least hydrogen and argon.

The present invention also relates to a method of manufacturing a thin film semiconductor device formed on an insulating material, wherein a thin film containing tantalum as a main component is formed by a sputter deposition method in an atmosphere containing at least nitrogen and argon. It is characterized by including a first step and a second step of subjecting the thin film to hydrogenation treatment. At this time, the second step is also a step of implanting hydrogen ions.

The present invention also relates to a method of manufacturing a thin film semiconductor device formed on an insulating material, wherein a first step of forming a thin film containing α-structure tantalum as a main component, and the thin film is subjected to hydrogenation treatment. It is characterized by including a second step. At this time, the second step is also a step of implanting hydrogen ions.

Further, the present invention is characterized in that in an electronic device provided with wiring formed on an insulating material, at least a part of the wiring is tantalum having an α structure containing hydrogen.

Further, the present invention is characterized in that in an electronic device provided with a wiring formed on an insulating material, the wiring is tantalum containing nitrogen and hydrogen.

Further, the present invention is a method of manufacturing an electronic device having wiring formed on an insulating material, wherein tantalum is the main component by a sputter deposition method in an atmosphere containing at least hydrogen, nitrogen and argon. It is characterized by including a step of forming a thin film.

The present invention also provides a method of manufacturing an electronic device including a lower conductive layer and an upper conductive layer having an α-structure tantalum as a main component, wherein the lower conductive layer is formed. It is characterized by including one step and a second step of forming a thin film containing α-structure tantalum as a main component by a sputter deposition method in an atmosphere containing at least hydrogen and argon.

The present invention also provides a method of manufacturing an electronic device having wiring formed on an insulating material, wherein a thin film containing tantalum as a main component is formed by a sputter deposition method in an atmosphere containing at least nitrogen and argon. It is characterized by including a first step of forming and a second step of subjecting the thin film to hydrogenation treatment. At this time, the second step is also a step of implanting hydrogen ions.

The present invention also relates to a method of manufacturing an electronic device formed on an insulating material, comprising a first step of forming a thin film containing α-structure tantalum as a main component, and a hydrogenation treatment of the thin film. It is characterized by including two steps. At this time, the second step is also a step of implanting hydrogen ions.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic principle and operation of the present invention will be described below with reference to the drawings.

(Chapter 1, Electronic Device of the Present Invention and Manufacturing Method Thereof) The electronic device of the present invention comprises an electrically conductive wiring formed on an insulating material. Examples of these electronic devices include thin film semiconductor devices (TFT), metal-insulator-metal nonlinear elements (MIM), solar cells, semiconductor devices (LSI), and printed wiring boards. At least a part of this electrically conductive wiring uses tantalum (Ta) having an α structure containing hydrogen. α
Structural tantalum has a cubic crystal system, and its crystal structure is body-centered cubic (bcc). The specific resistance of this α-structure tantalum is about 20 μΩcm to 60 μΩcm.
Such α-structure tantalum contains hydrogen in the film of α-structure tantalum simple substance, contains a small amount of nitrogen together with hydrogen in the film, and the conduction layer is located on the lower conduction layer and directly above it. In some cases, the upper conductive layer is formed, and the upper conductive layer mainly contains α-structure tantalum containing hydrogen. In any case, the main component is tantalum.
When the upper conductive layer containing tantalum as a main component is formed directly on the lower conductive layer, the lower conductive layer is made of thin niobium (Nb), tungsten (W), tantalum nitride having a thickness of about 20 nm to 200 nm. (TaN) and the like. The characteristic of these materials is recognized in that it is a conductive material capable of making the tantalum of the upper conductive layer into an α structure.

Generally, conventional α-structure tantalum (particularly nitrogen-containing α-structure tantalum) has very strong internal stress when deposited and formed by a PVD method such as a sputter method. However, since the α-structure tantalum of the present invention contains a small amount of hydrogen, the internal stress is remarkably relaxed. The hydrogen content in the tantalum thin film is 10 atm ppm (1
The atm ppm is from about 1 hydrogen atom to 10 ⁶ tantalum atoms) to about 5000 atm ppm.
When the hydrogen content is much higher than about 5000 atm ppm, tantalum exhibits brittleness and peels off from the substrate covered with the insulating material, or the wire breaks.
If it is about 000 atm ppm or less, the internal stress becomes sufficiently small and the α-structure tantalum becomes ductile. That is, even in a system in which the coefficient of thermal expansion is significantly different from that of the substrate, the resistance to stress and thermal expansion and contraction due to the difference is increased. On the contrary, the hydrogen content is 10 atm pp
If it is a very small amount of about m or less, the effect of hydrogen content does not appear, and it has a strong internal stress like conventional α-structure tantalum and ends up. After all, the hydrogen-containing α-structure tantalum used in the electronic device of the present invention is 10 times as compared with the conventional β-structure tantalum.
It has a low specific resistance of about 1/4 to 1/4, the internal stress is sufficiently relaxed, and the film exhibits ductility. Such a privilege is that the substrate on which the tantalum thin film is formed is a substance such as glass or plastic whose coefficient of thermal expansion is greatly different from that of a metal, or a substance which easily causes deformation or distortion of the substrate. It is sometimes clearly recognized.

Such hydrogen-containing α-structure tantalum of the present invention is prepared by the following manufacturing method. The first manufacturing method is to form a thin film containing tantalum as a main component by a sputter deposition method in an atmosphere containing at least hydrogen, nitrogen and argon. In the usual sputtering method, argon was introduced into the film forming chamber to generate plasma, and the thin film was deposited using this argon plasma. On the other hand, in the present invention, although the main constituent gas argon is unchanged,
Furthermore, a small amount of nitrogen and hydrogen are added to form a mixed plasma of argon nitrogen hydrogen, and this is used to sputter deposit a thin film containing tantalum as a main component. The optimum nitrogen content in argon is about 5.0% to 8.5%. When the film is formed within this range, α-structure tantalum having a small specific resistance and a relatively weak internal stress is formed. This is because a small amount of α-structure tantalum nitride (TaN) region is generated in the sputter-deposited tantalum thin film, and the main component tantalum is α-structured using this tantalum nitride region as a seed. Tantalum nitride itself has an α structure, but this has a large specific resistance and internal stress is tight and strong. Therefore, if the nitrogen content during film formation is too high, the proportion of tantalum nitride in the tantalum thin film increases, and as a result, the deposited thin film has a large specific resistance and strong internal stress. On the other hand, if the nitrogen content is too low, the tantalum thin film does not become α structured and β
Since it has a structure, the specific resistance is as high as about 200 μΩcm, and the internal stress also becomes stronger due to the addition of nitrogen, and the storage is completed. The hydrogen content in argon varies from about 10 atm ppm to 500 depending on the deposition rate of the tantalum thin film.
It is necessary to adjust it to be about 0 atm ppm, but its standard value is about 0.1% to 10%. After all, when a tantalum thin film is deposited in an atmosphere in which the nitrogen content in argon is about 5.0% to 8.5%, a low resistance film having an α structure with relatively small internal stress is formed, and 10 atm is further formed on this film. From about ppm to 5000 atm
When hydrogen of about ppm is added, the internal stress is further reduced, and at the same time, the ductility of the film is increased.

The second manufacturing method is applied when the electronic device includes a lower conductive layer and an upper conductive layer which is formed immediately above and has an α-structure tantalum as a main component. First, as a first step, a lower conductive layer is formed. This conductive layer is a material capable of α-structuring the tantalum of the upper conductive layer formed later as described above. This thin film is deposited by a PVD method such as an ordinary sputter method or vapor deposition method, or a CVD method. In the second step, tantalum in the upper conductive layer is formed by the sputter method, so if the lower conductive layer in the first step is also deposited with the same sputter, the first and second steps can be processed continuously without breaking the vacuum. I can. This not only improves productivity, but also allows the upper conductive layer to easily take over the crystal structure of the lower conductive layer, which ensures that the upper tantalum thin film is α-structured. There is. In the subsequent second step, a thin film containing α-structure tantalum as a main component is formed by a sputter deposition method in an atmosphere containing at least hydrogen and argon. As in the previous case, the hydrogen content in argon is adjusted so that the formed α-structure tantalum contains hydrogen at about 10 atm ppm to about 5000 atm ppm. Therefore, the value is about 0.1% to about 10%.

In the third manufacturing method, a thin film containing α-structure tantalum as a main component is first formed in the first step, and then the thin film is subjected to hydrogenation treatment in the second step to add a desired amount of hydrogen to the thin film. To do. The tantalum thin film formed in this first step usually has a strong internal stress. For this reason, when the thin film undergoes a large temperature change, cracks and peeling of the film due to internal stress occur and end up. Therefore, it is ideal to perform the hydrogenation treatment in the second step without changing the thermal environment such as cooling and heating as much as possible. It is desired that the process temperature from the completion of the first process to the second process is at least equal to or lower than the substrate processing temperature of the first process. However, this restriction can be relaxed if the tantalum thin film does not cause the above-mentioned problems in consideration of the substrate. As described above, the sputter deposition method may be performed in an atmosphere containing at least nitrogen and argon in order to form a thin film mainly containing tantalum of α structure in the first step. Nitrogen content in argon during sputter deposition is from about 5.0% to 8.5.
%. Another method for forming a thin film containing α-structured tantalum as a main component is to form a tantalum thin film on the lower conductive film by sputtering. This corresponds to the second manufacturing method in which hydrogen is not added. That is, it is a method of forming a lower conductive film capable of forming an α structure of upper tantalum such as niobium, tungsten, or tantalum nitride, and then sputter depositing tantalum directly on this film. In this way, after forming a thin film consisting mainly of α-structured tantalum by various methods in the first step, before the thin film undergoes a large temperature change that causes phenomena such as peeling and cracking, This is because hydrogen is added in the process to reduce the stress of the thin film. The hydrogenation treatment in the second step can be performed by hydrogen ion implantation, hydrogen plasma treatment, heat treatment in a hydrogen-containing atmosphere, or the like. If the second hydrogen plasma treatment is a continuous treatment with a sputter device in which a tantalum thin film is deposited in the first step, the hydrogenation efficiency will increase because there is no oxide film or contamination on the tantalum film surface, and at the same time the first step Since no extra step is inserted between the second step and the second step, the internal stress can be relaxed before the thin film is subjected to thermal stress. Of course, productivity is improving at this time. If hydrogenation is performed by hydrogen ion implantation, the amount of hydrogen added to the thin film can be adjusted precisely. In other words, the physical properties of the tantalum thin film can be changed freely. This method is particularly useful when the hydrogen-containing α-structure tantalum of the present invention is used for the gate electrode of the upper gate type thin film semiconductor device described later. This is because, after the α-structure tantalum to be the gate electrode is formed in the first step, the second step of hydrogen addition can also be used in the ion implantation step of forming the source / drain regions by using the gate electrode as a mask. In this way, the present invention can be achieved without increasing the number of special steps for hydrotreating.

(Chapter 2, Outline of Thin Film Semiconductor Device of the Present Invention and Method of Manufacturing the Same) Next, among the electronic devices described in Chapter 1, the thin film semiconductor device and the method of manufacturing the thin film semiconductor device according to the present invention will be described. explain. 1A to 1D are schematic cross-sectional views showing a manufacturing process of a thin film semiconductor device for forming a MIS field effect transistor. As shown in this figure, the thin film semiconductor device to which the present invention is particularly useful is a so-called upper gate type TFT. That is, the thin film semiconductor device of the present invention comprises a semiconductor layer formed in an island shape on an insulating material, a gate insulating layer formed on the semiconductor layer, and a gate electrode formed on the gate insulating layer. I have it. The present invention is applied to the low temperature process poly-Si TF using this figure.
Provides prior knowledge when applied to T.

In the present invention, general-purpose non-alkali glass is used as an example of the substrate 101. First, a base protective film 102, which is an insulating material, is formed on a substrate 101 by atmospheric pressure chemical vapor deposition (APCVD method), PECVD method, sputtering method, or the like. Next, a semiconductor film such as an intrinsic silicon film that will later become an active layer of the thin film semiconductor device is deposited. The semiconductor film is LPCV
It is formed by a chemical vapor deposition method (CVD method) such as D method, PECVD method, APCVD method or a physical vapor deposition method (PVD method) such as sputtering method or vapor deposition method. The semiconductor film thus obtained is irradiated with optical energy such as laser light or electromagnetic wave energy for a short time to proceed with crystallization. If the initially deposited semiconductor film is amorphous or has a mixed crystal quality in which amorphous and microcrystal are mixed, this process is called crystallization. On the other hand, if the initially deposited semiconductor film is polycrystalline, this process is called recrystallization. In the present specification, both are simply referred to as crystallization unless otherwise specified. If the energy intensity of laser light or the like is high, the semiconductor film is once melted during crystallization and then crystallized through a cooling and solidifying process.
This is referred to as a melt crystallization method in the present application. On the other hand, a method of advancing crystallization of a semiconductor film in a solid phase without melting is called a solid phase growth method (SPC method). The solid-phase growth method is a heat treatment method (Furnace-SPC method) for promoting crystallization at a temperature of about 550 ° C. to 650 ° C. for several hours to several tens of hours.
Then, from 700 ° C to 10 minutes in less than 1 second to 1 minute.
Rapid heat treatment method (RTA) that promotes crystallization at a high temperature of 00 ° C
Method) and a very short time solid phase growth method (VST-SPC method) which occurs when the energy intensity of laser light or the like is low. The present invention can be applied to any of these crystallization methods, but in view of manufacturing a large substrate with high productivity, the melt crystallization method, the RTA method, the VST method, and the like.
-The SPC method is particularly suitable. In these crystallization methods, the irradiation time is extremely short and the irradiation area is local to the entire substrate, so the entire substrate is not heated during crystallization of the semiconductor film, and therefore the heat of the substrate is not applied. This is because the resulting deformation and cracks do not occur. After that, this semiconductor film is patterned to form a semiconductor film 103 which becomes an active layer of a transistor later. (FIG. 1A) After forming the semiconductor film, the gate insulating film 104 is formed by a CVD method, a PVD method, or the like. Although various manufacturing methods can be considered for forming the insulating film, the insulating film forming temperature is preferably 350 ° C. or lower. This is important for preventing thermal deterioration of the MOS interface and the gate insulating film. The same applies to all steps below. All process temperatures after forming the gate insulating film must be kept below 350 ° C. By doing so, a high-performance thin film semiconductor device can be easily and stably manufactured.

Subsequently, a thin film to be the gate electrode 105 is deposited by the PVD method or the CVD method. Normally, the gate electrode and the gate wiring are made of the same material in the same process, and therefore it is desired that this material has a low electric resistance and is stable against a heat process of about 350 ° C. After depositing a thin film to be a gate electrode, patterning is performed, and then impurity ion implantation 106 is performed on the semiconductor film to form a source / drain region 107 and a channel region 108. (Fig. 1
(C) Since the gate electrode serves as a mask for ion implantation at this time, the channel has a self-aligned structure formed only under the gate electrode. Impurity ion implantation is an ion doping method in which a hydride of an impurity element and hydrogen are implanted using a mass non-separation type ion implantation apparatus, and an ion implantation method in which only a desired impurity element is implanted using a mass separation type ion implantation apparatus. Two types of can be applied. As a source gas for the ion doping method, a hydride of an implanted impurity element such as phosphine (PH ₃ ) or diborane (B ₂ H ₆ ) diluted in hydrogen at a concentration of about 0.1% to 10% is used. In the ion implantation method, hydrogen ions (protons and hydrogen molecule ions) are subsequently implanted after only the desired impurity element is implanted. As described above, in order to keep the MOS interface and the gate insulating film stable, the substrate temperature at the time of ion implantation is 35, whether it is the ion doping method or the ion implantation method.
Must be below 0 ° C. On the other hand, in order to always stably activate the implanted impurities at a low temperature of 350 ° C. or lower, it is desirable that the substrate temperature at the time of ion implantation is 200 ° C. or higher. In order to surely activate the impurity ions implanted at a low concentration at a low temperature such as performing channel doping to adjust the threshold voltage of the transistor or creating an LDD structure, it is necessary to Substrate temperature is 250
It must be above ℃. When the ion implantation is performed at such a high substrate temperature, recrystallization also occurs at the time of crystal breakage accompanying the ion implantation of the semiconductor film, and as a result, the ion implantation portion can be prevented from becoming amorphous. Because it is. That is, the ion-implanted region remains crystalline after the implantation, and the implanted ions can be activated even if the activation temperature thereafter is as low as about 350 ° C. or lower.
When forming a CMOS TFT, one of NMOS and PMOS is alternately covered with a mask using a suitable mask material such as polyimide resin, and the respective ions are implanted by the above-mentioned method. If the substrate temperature at the time of ion implantation is about 300 ° C. or less, it becomes possible to use a general-purpose photoresist which is cheap and easy to handle such as storage instead of the polyimide resin as a mask for the ion implantation.

Next, the interlayer insulating film 109 is formed by the CVD method or P
It is formed by the VD method. After ion implantation and interlayer insulating film formation, 3
Heat treatment is carried out for several tens of minutes to several hours in an appropriate thermal environment of about 50 ° C. or less to activate implanted ions and bake the interlayer insulating film. This heat treatment temperature is preferably about 250 ° C. or higher in order to surely activate the implanted ions. Further, a temperature of 300 ° C. or higher is preferable to effectively bake the interlayer insulating film. Generally, the film quality of the gate insulating film is different from that of the interlayer insulating film. Therefore, when the contact holes are formed in the two insulating films after the interlayer insulating film is formed, the etching rates of the insulating films are usually different. Under such a condition, the shape of the contact hole becomes wider toward the lower side in the shape of an inverse taper or an eaves is generated, which ends up causing a so-called contact failure in which electrical continuity cannot be established when an electrode is formed thereafter. Effectively baking the interlayer insulating film can minimize the occurrence of such contact failure. After forming the interlayer insulating film, contact holes are opened on the source / drain, and the source / drain extraction electrode 110 and these wirings are formed by the PVD method or the CVD method to complete the thin film semiconductor device. (FIG. 1 (d)) (Chapter 3, Detailed Description of Thin Film Semiconductor Device and Manufacturing Method Thereof of the Present Invention) The hydrogen-containing α-structure tantalum described in Chapter 1 can be applied to various electronic devices. However, the most important features of this conductive material are low specific resistance, low internal stress, and ductility. Such features include electronic devices with long wiring, electronic devices whose wiring physical properties are significantly different from those of the wiring, electronic devices that need to overcome a step that cannot be ignored with respect to the thickness of the wiring, or internal stress of the wiring It is often used in electronic devices that affect performance. An example of electronic equipment that satisfies this condition is a thin film semiconductor device formed on a glass substrate used for a solar cell or a liquid crystal display device. This is because the wiring length of these electronic devices extends from several cm to several tens of cm, and the thermophysical properties of the substrate and the wiring material are usually greatly different. Therefore, it can be said that the thin film semiconductor device used for a solar cell or a liquid crystal display device has a particularly large effect among the electronic devices of the present invention. As described in Chapter 2, in the thin film semiconductor device, three kinds of electrically conductive materials, that is, a gate electrode / wiring, a source electrode / wiring, and a drain electrode / wiring are formed on an insulating substance. Hydrogen-containing α-structure tantalum can be applied to any of these three types of electrically conductive materials. From the viewpoint of overcoming a step that cannot be ignored with respect to the thickness of the wiring, the source electrode / wiring or drain electrode / wiring of the lower gate type TFT or the upper gate type T
When applied to various electrodes and wirings of FT, another effect of suppressing disconnection at the step portion is added. Furthermore, the internal stress of the wiring does not adversely affect the transistor characteristics and the manufacturing process is simple.
It is added when used for the gate electrode and wiring of FT. This will be explained below.

The hydrogen-containing α-structure tantalum described in Chapter 1 is applied to the gate electrode / wiring of the upper gate type TFT described in Chapter 2. That is, at least part of the gate electrode is α-structured tantalum containing hydrogen. Of course, the gate electrode may be tantalum containing nitrogen and hydrogen. This gate electrode is formed by each manufacturing method described in Chapter 1. Although the ion implantation process for forming the source / drain regions is being refrained from after forming the gate electrode, in the case of α-tantalum containing hydrogen and nitrogen, some of these atoms must be in the lattice of the tantalum crystal. I'm in. Therefore, even if a small number of tentatively implanted ions pass through the lattice of the tantalum crystal during ion implantation with the gate electrode as a mask,
The ions collide with hydrogen atoms and nitrogen atoms existing between the lattices to change the moving direction. The thus-implanted implanted ions can no longer pass through the interstitial spaces, resulting in the gate electrode acquiring a complete blocking ability for the implanted ions. Thus, in the thin-film semiconductor device of the present invention, even if the gate electrode is a conductive crystal, the channel forming semiconductor region and the gate insulating film located immediately above the P-type or N-type for forming the source / drain. No type ions are introduced, and a highly reliable high performance TFT can be stably manufactured. Further, as described above, after the first step of forming a thin film mainly containing α-structure tantalum such as containing nitrogen, this thin film is processed into a gate electrode / wiring, and then a second step of hydrogenation treatment is performed on the source / drain regions. If the ion implantation step for forming is also used, the present invention can be achieved without increasing a special step. For example, when the source / drain regions are formed by ion doping, phosphine (PH
₃ ) or diborane (B ₂ H ₆ ), if the ion implantation step is performed after adjusting the concentration of hydrogen that dilutes the hydride of the implanted impurity element, α-structure tantalum containing the desired amount of hydrogen automatically Is obtained. The hydride and hydrogen concentrations of the implanted impurity element are easily adjusted by using a second diluent medium such as helium, neon, argon, krypton. Further, in the case of forming the source / drain by the ion implantation method with mass separation, hydrogen ions (protons and hydrogen molecule ions) are subsequently injected after the desired impurity element is injected. The purpose of this hydrogen implantation is to activate the impurities implanted in the source / drain regions at a low temperature of about 350 ° C. or lower, but of course it is also used to add hydrogen to the gate electrode. Therefore, even in the ion implantation method, the present invention can be achieved without increasing the number of special steps.

In the field effect thin film semiconductor device in which the active layer semiconductor film is in a polycrystalline state, the presence or absence of internal stress in the gate electrode affects the quality of the transistor. First
As described in the section, since the hydrogen-containing α-tantalum of the present invention has a very weak internal stress, when it is used for the gate electrode, it becomes a thin film semiconductor device showing good characteristics.

(Embodiment 1) FIGS. 1A to 1D show MIS.
FIG. 6 is a cross-sectional view showing a manufacturing process of a thin film semiconductor device for forming a field effect transistor.

In the first embodiment, the substrate 101 is 235 mm.
□ Alkali-free glass (OA-2 from Nippon Electric Glass Co., Ltd.) was used, but of course the type and size of the substrate are not limited as long as the substrate can withstand the maximum process temperature. First, a silicon dioxide film (SiO ₂ film) 102 serving as a base protection film is formed on a substrate 101 by atmospheric pressure chemical vapor deposition (APCVD method), PECVD method, sputtering method, or the like. In the APCVD method, monosilane (Si
A SiO ₂ film can be deposited using H ₄ ) or oxygen as a raw material. PE
In the CVD method and the sputtering method, the substrate temperature is from room temperature to 400.
It can be set to ℃. In the first embodiment, S is formed by the APCVD method.
2000 Å S at 300 ° C using iH ₄ and O ₂ as source gases
An iO ₂ film was deposited.

Then, an intrinsic silicon film to be an active layer of the thin film semiconductor device is deposited to about 500 Å. For the intrinsic silicon film, disilane (Si ₂ H ₆ ) which is a raw material gas is caused to flow in a high vacuum LPCVD apparatus at a flow rate of 200 SCCM and a deposition temperature of 425 ° C.
Deposited for 8 minutes. High vacuum type LP used in the first embodiment
The CVD device has a volume of 184.5 l. The 17 substrates were inserted into the reaction chamber kept at 250 ° C. with the front side facing down. After inserting the substrate, the turbo molecular pump was started to operate, and after reaching a steady rotation, a leak test was performed for 2 minutes.
The leak rate of degassing at this time is 3.1 × 10 ^-5 torr / min
It was. After that, the insertion temperature of 250 ° C to the deposition temperature of 4
The temperature was raised to 25 ° C. for one hour. During the first 10 minutes of heating, no gas was introduced into the reaction chamber and the temperature was raised in vacuum.
The minimum background pressure reached to the reaction chamber 10 minutes after the start of heating was 5.2.
It was × 10 ^-7 torr. During the remaining 50 minutes of temperature rising period, 300 SCCM of nitrogen gas having a purity of 99.9999% or higher was kept flowing. At this time, the equilibrium pressure in the reaction chamber is 3.0 × 10 ⁻³ to
It was rr. After reaching the deposition temperature, Si ₂ H ₆ which is the source gas
200 SCCM and helium (He) for dilution having a purity of 99.9999% or more was flowed at 1000 SCCM to deposit a silicon film for 58 minutes. The pressure immediately after introducing a gas such as Si ₂ H ₆ into the reaction chamber is 767 mtorr, and the pressure 57 minutes after introducing these source gases is 951 mtorr.
It was r. The thickness of the silicon film thus obtained is 50
1Å, 221mm □ excluding 7mm around the board
The film thickness variation within the square region was less than ± 5Å. Although the silicon film is formed by the LPCVD method in the first embodiment, the forming method is not limited to this and may be a PECVD method or a sputtering method. In the PECVD method and the sputtering method, the silicon film formation temperature can be set to room temperature to about 350 ° C.

The silicon film thus obtained has a high purity a.
-Si film. Next, this a-Si film is irradiated with optical energy or electromagnetic wave energy for a short time to crystallize a-Si and modify it into polycrystalline silicon (poly-Si). In Example 1, xenon chloride (XeCl)
Excimer laser (wavelength 308 nm) was irradiated.
The full width at half maximum intensity of the laser pulse is 45 ns. Since the irradiation time is such a very short time, the poly of a-Si
-The substrate is not heated during crystallization into -Si,
Therefore, the substrate is not deformed. Laser irradiation was performed in air with the substrate at room temperature (25 ° C.). The irradiation area for each laser irradiation is a square of 8 mm □, 4 for each irradiation.
Shift by mm. After first scanning in the horizontal direction (Y direction), then also shifting in the vertical direction (X direction) by 4 mm, again by shifting by 4 mm in the horizontal direction, and then scanning is repeated. Laser irradiation. This first laser irradiation energy density is 16
It was 0 mJ / cm ² . After the first laser irradiation is completed, the energy density is set to 275 mJ / cm ² and the second laser irradiation is performed on the entire surface. The scanning method is the same as the first laser irradiation, and scanning is performed by shifting the irradiation area of a square of 8 mm square by 4 mm in the Y direction and the X direction. Due to this two-stage laser irradiation, the entire substrate is a-Si to pol.
It is crystallized uniformly into y-Si. In Example 1, the XeCl excimer laser was used as the optical energy or the electromagnetic wave energy, but if the energy irradiation time is within several tens of seconds, it is not restricted by the energy source. For example, various lasers such as ArF excimer laser, XeF excimer laser, KrF excimer laser, YAG laser, carbon dioxide laser, Ar laser, dye laser, or lamp light such as arc lamp or tungsten lamp may be irradiated. . When performing arc lamp irradiation, the lamp output is set to about 1 kW / cm ² or more, and the irradiation time is set to about 45 seconds.
Modification of the membrane quality to Even during this crystallization, the energy irradiation time is short, so that the substrate is not deformed or cracked due to heat. Next, this silicon film was patterned to form a channel portion semiconductor film 103 to be an active layer of the transistor. (FIG. 1A) After that, the gate insulating film 104 is formed by an ECR-PECVD method or a PECVD method. In the first embodiment, a SiO ₂ film is used as a gate insulating film, and 1200 Å by PECVD method.
Deposited to a film thickness of. (FIG. 1B) Immediately before installing the substrate in the PECVD apparatus, the substrate was immersed in a 1.67% hydrofluoric acid aqueous solution for 20 seconds to remove the natural oxide film on the surface of the semiconductor film. The time from removing the oxide film to putting the substrate in the load lock chamber of the PECVD apparatus was about 15 minutes. This time is desired to be as short as possible from the viewpoint of cleaning the MOS interface, and it is preferably about 30 minutes at the longest.
In the PECVD method, monosilane (Si
H ₄ ) and laughing gas (N ₂ O) were used at a substrate temperature of 300 ° C. The plasma was set up with an rf wave of 13.56 MHz, an output of 900 W, and a vacuum degree of 1.50 torr. The flow rate of SiH ₄ was 250 SCCM and the flow rate of N ₂ O was 7000 SCCM. The deposition rate of the SiO ₂ film was 48.3 Å / s. Immediately before and immediately after forming SiO ₂ under these conditions, the silicon film and the formed oxide film were irradiated with oxygen plasma to improve the MOS interface and the oxide film. In the first embodiment, monosilane and laughing gas were used as the raw material gas, but TEOS (S
_{i- (O-CH 2 -CH 3} ) 4) may be used organic silane and an oxidizing gas such as oxygen or the like. Furthermore, although a PECVD apparatus with high versatility was used here, of course, ECR-PECV
The insulating film may be formed by a D device. What kind of CV
Even when the D apparatus or the source gas is used, the insulating film formation temperature is preferably 350 ° C. or lower. This is important for preventing thermal deterioration of the MOS interface and the gate insulating film. The same applies to all the following steps. All process temperatures after forming the gate insulating film must be kept below 350 ° C. By doing so, a high-performance thin film semiconductor device can be easily and stably manufactured.

Subsequently, a thin film to be the gate electrode 105 is deposited by the sputtering method vapor deposition method or the CVD method. In Example 1, tantalum (Ta) was selected as the gate electrode material and was deposited to a thickness of 500 nm by the sputtering method. The substrate temperature at the time of sputtering was 180 ° C., and argon (Ar) containing 6.7% of nitrogen (N ₂ ) was used as the sputtering gas. The optimum nitrogen content in argon is 5.0% to 8.5%. The crystal structure of the tantalum film obtained under these conditions is mainly α structure, and its specific resistance is 4
It is 0 μΩcm. Therefore, the sheet resistance of the gate electrode in Example 1 is 0.8Ω / □.

After depositing a thin film to be a gate electrode, a normal photo film is formed.
Patterning is performed by a lithographic method. photo
The heat treatment of the resist before exposure is 90 ° C, and the heat treatment after development is
It was at 130 ° C. Therefore, from the formation of α tantalum to ion implantation
The maximum process temperature until turning on is 130 ° C. Continued authenticity
Bucket type non-mass separated ion implanter for silicon film
(Ion doping method) is used to remove impurities such as phosphorus.
The ON implantation 106 is performed, and the source / drain regions 107 and
And the channel region 108 are formed. (Fig. 1 (c)) Book
In Example 1, the aim was to create an NMOS TFT, so
As the source gas, phosphine with a concentration of 5% diluted in hydrogen was used.
(PH₃), High frequency output 38W, acceleration voltage 80
5 × 10 at kV¹⁵1 / cm²Driven to the concentration of. At this time
At the same time, hydrogen is also injected into the gate electrode,
It becomes α-structure tantalum containing element. Against tantalum
The proportion of hydrogen is about 2000 atm ppm. high frequency
The output is a convenient value of about 20W to 150W.
It When creating a PMOS TFT, use the source gas
5% diborane (B₂H₆)
High frequency output from 20W to 150W, acceleration voltage
5 × 10 at 60kV ¹⁵1 / cm²Drive to a moderate concentration.
Also, when making CMOS TFTs, polyimide resin, etc.
Either NMOS or PMOS using the appropriate mask material
Alternately, cover each with a mask, and
Injection.

Next, an interlayer insulating film 109 is deposited by 5000 Å. In the first embodiment, PEC is made of SiO ₂ as an interlayer insulating film.
It was formed by the VD method. In the PECVD method, TEOS (Si— (O—CH ₂ —CH ₃ ) ₄ ) and oxygen (O ₂ ) were used as source gases at a substrate temperature of 300 ° C. Plasma is output 800 by rf wave of 13.56MHz
It was set up under the conditions of W and a vacuum degree of 8.0 torr. TE
The OS flow rate is 200 SCCM and the O ₂ flow rate is 8000S.
It was CCM. At this time, the deposition rate of the SiO ₂ film is 12 n
It was m / s. After such ion implantation and formation of the interlayer insulating film, heat treatment was performed in an oxygen atmosphere at 300 ° C. for 1 hour to activate the implanted ions and to bake the interlayer insulating film. The heat treatment temperature is preferably 300 ° C to 350 ° C. After that, the contact hole is opened, and the source / drain extraction electrode 110 is formed by the sputtering method or the like to complete the thin film semiconductor device. (FIG. 1D) Indium tin oxide (ITO) or aluminum (Al) is used for the source / drain extraction electrodes. The substrate temperature during the sputtering of these conductors is about 100 ° C to 250 ° C.

The transistor characteristics of the thin-film semiconductor device thus prototyped were measured, and the source-drain current Ids when the transistor was turned on at the source-drain voltage Vds = 4V and the gate voltage Vgs = 10V was determined to be the on-current ION. Is defined as ION = (2
It was 3.3 + 1.73, −1.51) × 10 ⁻⁶ A.
The off-current when the transistor is turned off at Vds = 4V and Vgs = 0V is IOFF = (1.16 + 0.38,
It was −0.29) × 10 ⁻¹² A. Here, the measurement is performed at a temperature of 25 ° C., the length L of the channel portion is 10 μm, and the width W is
= 10 μm transistor. Effective electron mobility (J. Levinson) determined from the saturation current region
et al. J, Appl, Phys. 53, 119
3'82), μ = 50.92 ± 3.26 cm ² / v. s
It was ec. On the other hand, the conventional low temperature process poly-
In Si TFT, ION = (18.7 + 2.24,
−2.09) × 10 ⁻⁶ A, IOFF = (4.85 + 3.8)
8, −3.27) × 10 ⁻¹² A. Thus, according to the present invention, it is possible to manufacture an excellent and uniform thin film semiconductor device having high mobility, Ids changing by 7 digits or more with respect to the modulation of the gate voltage of 10 V, and having a small variation. It was Therefore, when the thin film semiconductor device of the present invention is applied to an LCD,
It is possible to obtain uniform high image quality over the entire LCD screen.

[0040]

As described above in detail, in the electronic device of the present invention, the hydrogen-containing α-tantalum used in the electronic device has a low specific resistance, weak internal stress, and ductility. Therefore, the following effects are recognized.

(1) In a large electronic device, even if the wiring is long, the specific resistance is low, so that the potential drop in the wiring is small. That is, when the electric energy is transported, the energy loss accompanying the transportation is small, and when transmitting the electric signal, an accurate signal can be transmitted. Therefore, when the present invention is applied to, for example, a solar cell, energy conversion efficiency is improved, and when it is used in, for example, a liquid crystal display device, a beautiful display can be obtained over a large screen.

(2) Even if the substrate of the electronic device is a substance such as glass, ceramics, or plastic whose physical properties are remarkably different from that of the metal, disconnection is unlikely to occur. In addition, these electronic devices can be used in a wide temperature range.

(3) Since the wiring material exhibits ductility, even if there is a step that cannot be ignored compared with the film thickness of the wiring material, it can be easily overcome. Therefore, when it is applied to a multilayer wiring of an LSI, a printed wiring board, or the like, highly reliable wiring can be obtained even if there are some irregularities in the wiring portion.

(4) The ion blocking ability in the ion implantation is excellent. Therefore, when used for the gate electrode of the upper gate type TFT, the thin film semiconductor device has high performance and high reliability.

(5) Upper gate type low temperature process po
When applied to the ly-Si TFT, it is not necessary to add a special process to the conventional manufacturing process.

(6) Upper gate type low temperature process po
When applied to a ly-Si TFT, the electrical characteristics of the transistor are good.

[Brief description of drawings]

FIG. 1 is a sectional view of an element in each step of manufacturing a thin film semiconductor device showing an example of the present invention.

[Explanation of symbols]

101 ... Substrate 102 ... Base protection film 103 ... Semiconductor film 104 ... Gate insulating film 105 ... Gate electrode 106 ... Ion implantation 107 ... Source / drain regions 108 ... Channel area 109 ... Interlayer insulating film 110 ... Source / drain extraction electrodes

[Procedure amendment]

[Submission date] September 9, 2002 (2002.9.9)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Thin film semiconductor device and electronic equipment

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

A thin film semiconductor device of the present invention is a thin film semiconductor device formed on a substrate, comprising: a semiconductor layer formed on the substrate; and a gate insulating layer formed on the semiconductor layer. A gate electrode formed on the gate insulating layer, the gate electrode having a thickness of 10 to 5000 atm pp.
It is characterized by being a α-structure tantalum containing hydrogen at a concentration of m. Further, the semiconductor layer is formed in an island shape on the substrate. Further, the thin film semiconductor device of the present invention is a thin film semiconductor device formed on a substrate, wherein a semiconductor layer formed on the substrate, a gate insulating layer formed on the semiconductor layer, and a gate insulating layer formed on the gate insulating layer. A formed gate electrode, the gate electrode comprising nitrogen and 10
It is characterized by being tantalum containing hydrogen at a concentration of up to 5000 atm ppm. Further, the semiconductor layer is formed in an island shape on the substrate. The electronic device of the present invention is an electronic device formed on a substrate, wherein the wiring formed on the substrate is 10 to 5000 atm ppm.
It is characterized by being an α-structure tantalum containing hydrogen at a concentration of. Further, the electronic device of the present invention is characterized in that, in the electronic device formed on the substrate, the wiring formed on the substrate is tantalum containing nitrogen and hydrogen at a concentration of 10 to 5000 atm ppm. To do. The present invention provides a thin film semiconductor device including a semiconductor layer formed in an island shape on an insulating material, a gate insulating layer formed on the semiconductor layer, and a gate electrode formed on the gate insulating layer. At least a part of the gate electrode is made of tantalum having an α structure containing hydrogen.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 29/78 617J 21/88 MF term (reference) 2H092 JA25 JA37 KA18 MA05 MA07 MA27 NA15 NA27 NA28 NA29 4M104 AA09 BB17 BB37 DD41 DD43 5F033 HH17 HH19 HH21 HH32 LL01 LL06 NN03 PP06 PP15 PP16 QQ59 QQ61 RR04 SS04 SS15 VV06 VV15 5F052 AA02 AA24 BB01 EE02 BB02 BB02 BB01 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB06 BB01 BB06 BB01 EE45 EE47 EE48 FF02 FF28 FF30 FF31 GG02 GG13 GG25 GG35 GG42 GG43 GG45 GG47 HJ01 HJ04 HJ12 HJ13 HJ23 HL03 HL07 HL23 HL24 HM03 HM15 NN02 NN23 NN34 NN35 NN40 PP03 PP05

Claims (16)

[Claims] 1. A thin film semiconductor including an island-shaped semiconductor layer formed on an insulating material, a gate insulating layer formed on the semiconductor layer, and a gate electrode formed on the gate insulating layer. In the device, at least a part of the gate electrode is tantalum having an α structure containing hydrogen, and a thin film semiconductor device. 2. A thin film semiconductor comprising an island-shaped semiconductor layer formed on an insulating material, a gate insulating layer formed on the semiconductor layer, and a gate electrode formed on the gate insulating layer. A thin film semiconductor device, wherein the gate electrode is tantalum containing nitrogen and hydrogen. 3. A method of manufacturing a thin film semiconductor device formed on an insulating material, wherein a thin film containing tantalum as a main component is formed by a sputter deposition method in an atmosphere containing at least hydrogen, nitrogen and argon. A method of manufacturing a thin film semiconductor device, comprising the steps of: 4. A method for manufacturing a thin film semiconductor device including a lower conductive layer and an upper conductive layer mainly composed of α-structured tantalum, wherein a lower conductive layer is formed. A method of manufacturing a thin film semiconductor device, comprising: a step; and a second step of forming a thin film containing α-structure tantalum as a main component by a sputter deposition method in an atmosphere containing at least hydrogen and argon. 5. A method of manufacturing a thin film semiconductor device formed on an insulating material, wherein a thin film containing tantalum as a main component is formed by a sputter deposition method in an atmosphere containing at least nitrogen and argon. A method of manufacturing a thin film semiconductor device, comprising: a step; and a second step of subjecting the thin film to a hydrogenation treatment. 6. The method of manufacturing a thin film semiconductor device according to claim 5, wherein the second step is a hydrogen ion implantation step. 7. A method of manufacturing a thin film semiconductor device formed on an insulating material, comprising: a first step of forming a thin film containing α-structure tantalum as a main component; and a second step of subjecting the thin film to hydrogenation treatment. A method of manufacturing a thin film semiconductor device, comprising: 8. The method of manufacturing a thin film semiconductor device according to claim 7, wherein the second step is a hydrogen ion implantation step. 9. An electronic device provided with wiring formed on an insulating material, wherein at least a part of the wiring is tantalum having an α structure containing hydrogen. 10. An electronic device provided with wiring formed on an insulating material, wherein the wiring is tantalum containing nitrogen and hydrogen. 11. A method of manufacturing an electronic device having wiring formed on an insulating material, comprising: forming a thin film containing tantalum as a main component by a sputter deposition method in an atmosphere containing at least hydrogen, nitrogen and argon. A method of manufacturing an electronic device, comprising the step of forming. 12. A method of manufacturing an electronic device including a conductive layer composed of a lower conductive layer and an upper conductive layer mainly composed of α-structure tantalum, the first step of forming the lower conductive layer. And a second step of forming a thin film containing α-structure tantalum as a main component by a sputter deposition method in an atmosphere containing at least hydrogen and argon. 13. A method of manufacturing an electronic device having wiring formed on an insulating material, wherein a thin film containing tantalum as a main component is formed by a sputter deposition method in an atmosphere containing at least nitrogen and argon. A method of manufacturing an electronic device, comprising: a first step; and a second step of subjecting the thin film to a hydrogenation treatment. 14. The method of manufacturing an electronic device according to claim 13, wherein the second step is a hydrogen ion implantation step. 15. A method of manufacturing an electronic device formed on an insulating material, comprising: a first step of forming a thin film containing α-structure tantalum as a main component; and a second step of subjecting the thin film to hydrogenation treatment. A method for manufacturing an electronic device, comprising: 16. The method of manufacturing a thin film semiconductor device according to claim 15, wherein the second step is a hydrogen ion implantation step.