JP2010177621A - Semiconductor device, production process of the same, and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an Al alloy film to achieve a good contact characteristic with a Si film or a film containing Si as a main component without formation of a high-melting point barrier metal layer. <P>SOLUTION: A semiconductor device (TFT) includes oxidized low-ohmic resistance Si films 8 disposed on a Si semiconductor film 7 so as to form a channel 11, and a source electrode 9 and a drain electrode 10 which are directly connected to the low-ohmic resistance Si films 8, and comprise an aluminum alloy film containing at least Ni atoms, N atoms and O atoms in the vicinity of the connection interface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a structure of a semiconductor device such as an electro-optic display device such as a liquid crystal display device or an organic EL (electroluminescence) display device, or a semiconductor component, and a manufacturing method thereof, and particularly, an aluminum alloy film (hereinafter referred to as “Al alloy film”) And a manufacturing method of the semiconductor device including a Si film (silicon film) or a film containing Si as a main component.

  As an example of a semiconductor device, an electro-optic display device for a display device including an active matrix TFT using a thin film transistor (hereinafter referred to as “TFT”) as a switching element is low in power consumption and thin. It is one of the flat panel displays that take advantage of the characteristic features and replaces CRT (Cathode Ray Tube), and its application to products is actively made.

  Conventionally, as a material of a wiring or an electrode constituting a semiconductor device, for example, a metal such as titanium (Ti), chromium (Cr), molybdenum (Mo), tantalum (Ta), or tungsten (W), or these metals are used. A so-called refractory metal material made of an alloy having a main component has been generally used. These refractory metal materials have been used favorably as electrode materials for semiconductor devices because there is almost no interface diffusion reaction at the connection interface with the Si semiconductor film.

  However, with the recent increase in the size of TV screens and the progress of high-definition small displays in portable terminals such as mobile phones, there has been a significant demand for lower resistance in the wiring material of semiconductor devices for display devices. Therefore, the specific resistance value of conventional refractory metal materials (generally 12 μΩ · cm to 60 μΩ · cm) is not suitable.

  For this reason, as a wiring material of a semiconductor device for a display device, an aluminum alloy (Al) or an alloy containing Al as a main component, which has a lower specific resistance and is easy to process a wiring pattern, has a high melting point. As a substitute material for metal materials, it has been attracting attention.

  However, it is generally known that an Al alloy film undergoes a severe interdiffusion reaction at the junction interface with a Si semiconductor film or a film containing Si as a main component, thereby deteriorating its electrical characteristics. For this reason, when the Al alloy film is connected to the Si semiconductor film, it is necessary to interpose the refractory metal as a barrier layer.

  In the case of an electro-optic display device for a display device, an indium oxide system generally used as a transmissive pixel electrode material, for example, an ITO (Indium Tin Oxide) film formed by mixing indium oxide and tin oxide, and There is a need to join a wiring material (for example, an Al alloy film). In this case as well, in order to cause a diffusion reaction at the bonding interface with the ITO film and to deteriorate its electrical characteristics, it is also necessary to intervene a refractory metal material as a barrier layer. was there.

  A prior example in which a source / drain electrode of a TFT is formed by combining a low-resistance Al alloy film and a Si semiconductor film using a refractory metal material as described above as a barrier layer is disclosed in, for example, Patent Documents 1 to 3 Each of which is disclosed. In these prior examples, a low resistance formed by providing Cr, Mo, Ti, or Zr high melting point barrier metal (high melting point metal material) in the lower layer and adding the impurity to the high melting point barrier metal. A structure of a laminated film is disclosed in which a low resistance Al-based metal is formed on the upper surface of the refractory barrier metal after being directly bonded to the Si film (ohmic contact Si film) and the ITO film.

  On the other hand, methods for preventing the interfacial diffusion reaction between the Al alloy film and ITO or Si and obtaining good electrical characteristics (contact characteristics) at the interface are disclosed in Patent Documents 4 and 5, for example. That is, in Patent Document 4, by using an Al alloy film containing a predetermined amount of Ni, the Al alloy film containing Ni is directly bonded to each of the ITO film and the Si semiconductor film. A method for improving contact characteristics is disclosed. In Patent Document 5, an Al—Ni alloy film is used instead of the Al alloy film to improve the contact characteristics between the Al—Ni alloy film and the ITO film, and further, N is contained in Si. A method for improving the contact characteristics with the Si semiconductor film by bonding the SiAl—Ni alloy film and the Si semiconductor film through a layer is disclosed. If the methods disclosed in these Patent Documents 4 and 5 are used, at least in a device that requires direct bonding between an Al alloy film and ITO and direct bonding between an Al alloy film and an Si semiconductor film, a refractory metal is used. There is no need to form a barrier layer of material.

JP-A-6-236893 Japanese Patent Laid-Open No. 7-30118 JP-A-8-62628 JP 2003-89864 A JP 2008-10801 A

  In the combination of the conventional Al alloy film material and manufacturing process, as described above, the interfacial diffusion reaction between the Al alloy film and the Si semiconductor film or Si film containing Si as a main component cannot be prevented. A barrier layer made of a refractory metal material had to be formed. For this reason, as a result of an increase in the number of film forming processes and etching processes, which complicates the manufacturing process, the production capacity is reduced. In addition, unevenness occurs in the shape of the etched cross section due to the difference in the etching rate between the Al alloy film and the refractory metal material during the etching process and the difference in the amount of side etching that proceeds in the lateral direction. For this reason, fine processing has been difficult. Furthermore, the unevenness in the shape of the etched cross section deteriorates the coverage characteristics of the film formed in the upper layer.

  As described above, it is difficult to manufacture a semiconductor device having high quality and high reliability in the conventional method in which a high melting point barrier metal is interposed between an Al alloy film and a Si semiconductor film. There was a problem.

  Further, it has been found that the methods disclosed in Patent Documents 4 and 5 described above have the following problems.

  That is, according to the evaluation results of the present inventors, when an Al—Ni alloy film is directly formed as a source electrode and a drain electrode of a TFT using a Si semiconductor film, the Al—Ni alloy film and the Si semiconductor are formed immediately after the formation. Although no interdiffusion reaction at the interface with the film is observed, the interdiffusion reaction gradually proceeds by heat treatment (maintained in air or nitrogen gas atmosphere for about 30 minutes), and the temperature exceeds 250 ° C. In the air or nitrogen gas atmosphere, mutual diffusion reaction was observed even at the optical microscope observation level. At temperatures exceeding 200 ° C., no remarkable interdiffusion reaction was observed at the optical microscope observation level, but when the electrical characteristics of the TFT were measured, the TFT characteristics were clearly degraded. As a specific phenomenon, in a general Id (drain current) -Vg (gate voltage) characteristic of a TFT, an increase of one digit or more was observed in a leakage current (off current Ioff) that flows when switching is turned off. . This point is considered to be caused by the occurrence of local micro-diffusion between Al and Si at the bonding interface.

  On the other hand, when the Al—Ni alloy film is bonded to the Si semiconductor film via the layer containing N in Si, no interdiffusion reaction is observed up to at least 300 ° C., and the TFT off characteristics Also, no significant deterioration was observed. However, a phenomenon was observed in which the on-current (Ion) decreased to about 50% when the high melting point barrier metal layer was used. In addition, significant on-characteristic degradation due to heat treatment was also observed. For example, as a specific phenomenon, a decrease in ON current (Ion) of about 50% at the maximum was observed after the heat treatment at 300 ° C. as compared with immediately after the formation.

  In this regard, a process for manufacturing an active matrix TFT substrate for a general display device usually includes processing at a process temperature of at least 200 ° C., generally about 300 ° C. Accordingly, it has been found that application of such an Al alloy film to a semiconductor device is substantially difficult from the viewpoint of heat resistance.

  The present invention has been made in view of the recognition of such problems, and its main purpose is to have a Si film or Si as a main component without interposing a refractory barrier metal layer made of a refractory metal material. An object of the present invention is to provide a semiconductor device including an Al alloy film having good contact characteristics with a film to be formed and good heat resistance, and a method for manufacturing the same.

  A semiconductor device according to the subject of the present invention includes a film containing Si as a main component, and an aluminum alloy film directly bonded to the film containing Si as a main component. In the vicinity of the bonding interface with the aluminum alloy film, at least Ni atoms, O atoms and N atoms are included.

  According to the subject of the present invention, good contact with an oxide transparent conductive film such as an ITO film without interposing a refractory barrier metal layer made of a refractory and relatively high resistance refractory metal material such as Cr. It is possible to provide a semiconductor device provided with an Al alloy film having good characteristics, good contact characteristics with a Si film or a film containing Si as a main component, and heat resistance of the semiconductor device.

  Hereinafter, various embodiments of the present invention will be described in detail along with the effects and advantages thereof with reference to the accompanying drawings.

It is a front view which shows the structural example of the TFT array substrate used for a display apparatus. It is a top view which shows the active matrix type TFT substrate for a display which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view which shows the active matrix type TFT substrate for a display which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view which shows the manufacturing process of the active matrix type TFT substrate for a display which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view which shows the manufacturing process of the active matrix type TFT substrate for a display which concerns on Embodiment 1 of this invention. It is a top view which shows the active matrix type TFT substrate for a display which concerns on Embodiment 2 of this invention. It is a longitudinal cross-sectional view which shows the active matrix type TFT substrate for a display which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view which shows the manufacturing process of the active matrix type TFT substrate for a display which concerns on Embodiment 2 of this invention. It is a longitudinal cross-sectional view which shows the manufacturing process of the active matrix type TFT substrate for a display which concerns on Embodiment 2 of this invention. It is a figure which shows element distribution of the interface vicinity of Al alloy film and Si film. It is a figure which shows the relationship between Si-O existence ratio of the Si film surface of TFT using Al alloy film, and on-current ratio. It is a figure which shows the relationship between Si-N / Si-O existence ratio of the Si film surface of TFT using Al alloy film, and on-current ratio.

(Knowledge in the present invention)
According to the evaluation results of the present inventors, when the Al—Ni alloy film and the Si film are bonded via a layer containing N in the Si film (hereinafter referred to as “N-containing layer”), Since the N-containing layer is present at the bonding interface between Al and Si, the interdiffusion reaction between Al atoms and Si atoms is prevented. However, in the region where the Ni atoms contained in the Al—Ni alloy film are deposited, Ni is directly bonded to the Si film as a single metal or as an Al ₃ Ni compound phase without going through the N-containing layer, It has been clarified that the on-characteristics of the semiconductor device deteriorate due to the mutual diffusion reaction between the Ni atom and the Si atom from a temperature exceeding 200 ° C.

  In addition, the inventors of the present application can suppress the interdiffusion reaction between Ni atoms and Si atoms by interposing a layer containing O atoms at the bonding interface between the Al—Ni alloy film and the Si film. It became clear that it was possible.

  The present invention has been made based on the above findings.

  That is, one embodiment of a semiconductor device according to the present invention includes a film containing silicon (Si) as a main component and an aluminum alloy film directly bonded to a film containing Si as a main component, and Si as a main component. In the vicinity of the bonding interface between the film to be formed and the aluminum alloy film, at least nickel (Ni) atoms, oxygen (O) atoms, and nitrogen (N) atoms are included.

  Hereinafter, details of each embodiment of the present invention will be described with reference to the drawings. At that time, from the viewpoint of clarification of the description, omission and simplification are appropriately made in the following description and drawings. In each drawing, the same reference numerals are given to components having the same configuration or function and corresponding parts, and the description thereof is omitted.

(Configuration of display device common to each embodiment)
First, an example of a display device using a semiconductor device according to the present invention will be described with reference to FIG. Here, FIG. 1 is a front view schematically showing a configuration example of a TFT array substrate used in the display device. The display device according to the present invention is described by taking a liquid crystal display device as an example, but it is merely illustrative. As another display device according to the present invention, a flat display device (flat panel display) such as an organic EL display device may be used.

  The liquid crystal display device shown in FIG. The substrate 40 is an array substrate such as a TFT array substrate. The substrate 40 is provided with a display area 41 and a frame area 42 provided so as to surround the display area 41. In the display area 41, a plurality of gate lines (scanning signal lines) 43 and a plurality of source lines (display signal lines) 44 are formed. The plurality of gate lines 43 are provided in parallel to each other. Similarly, the plurality of source lines 44 are provided in parallel to each other. The gate wiring 43 and the source wiring 44 are formed so as to cross three-dimensionally. The gate wiring 43 and the source wiring 44 are orthogonal to each other. A region surrounded by the adjacent gate wiring 43 and the adjacent source wiring 44 is a pixel 47. Accordingly, a plurality of pixels 47 are arranged in a matrix on the substrate 40.

  A scanning signal drive circuit 45 and a display signal drive circuit 46 are provided in the frame area 42 of the substrate 40. Each gate line 43 extends from the display area 41 to the frame area 42, and is connected to the scanning signal drive circuit 45 at the end of the substrate 40. Similarly, each source line 44 extends from the display region 41 to the frame region 42 and is connected to the display signal drive circuit 46 at the end of the substrate 40. Further, an external wiring 48 is provided in the vicinity of the scanning signal driving circuit 45, and each wiring of the external wiring 48 is connected to a corresponding portion of the scanning signal driving circuit 45. In addition, an external wiring 49 is provided in the vicinity of the display signal driving circuit 46, and each wiring of the external wiring 49 is connected to a corresponding portion of the display signal driving circuit 46. The external wirings 48 and 49 are wiring boards made of, for example, FPC (Flexible Printed Circuit).

  The scanning signal driving circuit 45 and the display signal driving circuit 46 receive various signals supplied from the outside via the external wirings 48 and 49, respectively. That is, the scanning signal drive circuit 45 supplies a gate signal (scanning signal) to the gate wiring 43 based on a control signal from the outside. By this gate signal, the gate wiring 43 is sequentially selected. The display signal driving circuit 46 supplies a display signal to the source wiring 44 based on external display data. As a result, a display voltage corresponding to the display data is supplied to each pixel 47.

  In each pixel 47, at least one TFT 50 is disposed. In the case of this example, each TFT 50 is disposed in the vicinity of the solid intersection of the source wiring 44 and the gate wiring 43. Then, the display voltage is supplied to the pixel electrode of the pixel 47 to which each TFT 50 corresponds. That is, the TFT 50 which is a switching element is turned on by a gate signal from the gate wiring 43. Thereby, a display voltage is applied from the source line 44 to the pixel electrode connected to the drain electrode of the TFT 50. An electric field corresponding to the display voltage is generated between the pixel electrode and the counter electrode. An alignment film (not shown) is disposed on the surface of the substrate 40.

  Further, a counter substrate (not shown) is disposed to face the substrate 40. The counter substrate is, for example, a color filter substrate, and is disposed on the viewing side. On the counter substrate, a color filter, a black matrix (BM), a counter electrode, an alignment film, and the like are disposed. The counter electrode may be disposed on the substrate 40 side. A liquid crystal layer is sandwiched between the substrate 40 and the counter substrate. That is, liquid crystal is introduced between the substrate 40 and the counter substrate. Furthermore, a polarizing plate, a phase difference plate, and the like are provided on the outer surfaces of the substrate 40 and the counter substrate. A backlight unit or the like is disposed on the non-viewing side of the liquid crystal display panel.

  The liquid crystal is driven by the electric field between the pixel electrode and the counter electrode. That is, the alignment direction of the liquid crystal between the substrates changes. As a result, the polarization state of the light passing through the liquid crystal layer changes. That is, the polarization state of light that has passed through the polarizing plate and has become linearly polarized light is changed by the liquid crystal layer. Specifically, light from the backlight unit becomes linearly polarized light by the polarizing plate on the array substrate side. When the linearly polarized light passes through the liquid crystal layer, the polarization state changes.

  Depending on the polarization state, the amount of light passing through the polarizing plate on the counter substrate side changes. That is, the amount of light that passes through the polarizing plate on the viewing side in the transmitted light that is emitted from the backlight unit and passes through the liquid crystal display panel changes. The alignment direction of the liquid crystal changes depending on the applied display voltage. Therefore, the amount of light passing through the viewing-side polarizing plate can be changed by controlling the display voltage. That is, a desired image can be displayed by changing the display voltage for each pixel 47.

  The above description is the outline of the configuration and operation of the display device. Below, each aspect of the semiconductor device which concerns on this invention applied to this display apparatus, and its manufacturing method is described.

(Embodiment 1)
As this embodiment, an active matrix TFT substrate for a liquid crystal display device using liquid crystal as a display element will be described in detail.

  FIG. 2 is a plan view showing an example of a planar structure of the TFT substrate, and FIG. 3 is a longitudinal sectional view showing a structure such as a cross section along line AA in FIG. In particular, FIG. 3 shows an AA cross section, a BB cross section, and a CC cross section shown in FIG. 2 in order to facilitate the description of the manufacturing process of the TFT substrate. Specifically, in FIG. 3, in addition to the AA cross section (right side) including the TFT and the pixel portion, the BB cross section (left side) including the gate terminal portion 4 and the source terminal portion 13 are included. A CC cross section (intermediate) is shown. Similarly, the longitudinal sectional views used in the following description show a plurality of sectional structures.

  2 and 3, the transparent insulating substrate 1 is a substrate made of glass or plastic. On the transparent insulating substrate 1, a gate electrode 2 made of a metal film, a gate wiring 3 connected to the gate electrode 2, a gate terminal 4 connected to the gate wiring 3 and for inputting an image scanning signal, and The auxiliary capacitance electrode 5 is formed at least. Further, a gate insulating film 6 is provided as an upper layer of these constituent parts 2, 3, 4 and 5. Further, the Si semiconductor film 7 becomes a constituent element of the TFT provided in the vicinity of the lower gate electrode 2 through the gate insulating film 6. The ohmic low resistance Si film 8 is a semiconductor film formed by adding impurities to Si. The source electrode 9 and the drain electrode 10 are both made of an Al alloy film and are directly connected to the ohmic low-resistance Si film 8 respectively.

  The channel portion 11 of the TFT is configured in a region where the source electrode 9 and the drain electrode 10 are separated and the ohmic low resistance Si film 8 is further removed. The source wiring 12 is a wiring connected to the source electrode 9. In FIG. 3, the boundary between the source electrode 9 and the source wiring 12 is not clearly shown. 3 is connected to the source wiring 12 and receives a video signal from the outside, and inputs the video signal to the source electrode 9 through the source wiring 12. Also, the interlayer insulating film 14 in FIG. 3 is disposed so as to cover the entire substrate including the channel portion 11.

  As shown in FIG. 3, a plurality of openings (three in the example of FIG. 3) are arranged in the interlayer insulating film 14. Among these openings, the pixel drain contact hole 15 is an opening reaching the lower drain electrode 10. The gate terminal contact hole 16 is an opening that reaches the gate terminal 4. Further, the source terminal contact hole 17 is an opening reaching the source terminal 13. The transmissive pixel electrode 18 is a transparent conductive film connected to the drain electrode 10 through the pixel drain contact hole 15. The gate terminal pad 19 is a pad connected to the gate terminal portion 4 through the gate terminal portion contact hole 16. Further, the source terminal pad 20 is a pad connected to the source terminal portion 13 through the source terminal portion contact hole 17.

  The active matrix TFT substrate configured as described above and a counter substrate provided with a color filter for color display, a counter electrode, and the like are bonded to each other with a certain gap (cell gap), and a liquid crystal is put in this. By injecting and sealing, a semiconductor device which is an electro-optical display device for display use is manufactured.

  Next, the procedure of the manufacturing method of the active matrix TFT substrate according to the present embodiment will be described based on (A) to (C) of FIG. 4 and (D) to (E) of FIG. In FIG. 4A, first, a transparent insulating substrate 1 such as a glass substrate is cleaned using a cleaning liquid or pure water, and a metal film is formed on the transparent insulating substrate 1. After the formation of the metal film, the metal film is patterned by a first photolithography process to form the gate electrode 2, the gate wiring 3, the gate terminal portion 4, and the auxiliary capacitance electrode 5. As the metal film, it is preferable to use a metal or alloy having a low electrical specific resistance.

As a preferred embodiment, first, an AlNi alloy film containing 2 mol% (at%) Ni is formed to a thickness of about 200 nm by a sputtering method using a known argon (Ar) gas or krypton (Kr) gas. Film. Regarding sputtering conditions, it is a DC (direct current) magnetron sputtering method, using an AlNi alloy target containing 2 mol% of Ni in Al, a deposition power density of 3 W / cm ² , and an Ar gas flow rate of 2.4 × 10 ⁻³ m. ^An AlNi alloy film was formed under the condition of ³ / h (40 sccm). Next, after forming a photoresist pattern by a photolithography process, the AlNi alloy film was etched using a chemical solution of a known phosphoric acid + nitric acid + acetic acid system. Thereafter, the pattern of the gate electrode 2, the gate wiring 3, the gate terminal portion 4, and the auxiliary capacitance electrode 5 was formed by removing the photoresist pattern. At this time, the Ni composition of the formed AlNi alloy film was 2 mol% Ni which is almost the same as the target composition. The specific resistance value was about 12 μΩ · cm immediately after film formation, but after passing through the process temperature of about 300 ° C. shown below, the specific resistance value was reduced to about 5 μΩ · cm. It had been. This value is lower than that of a general conventional refractory metal, and the resistance of the gate wiring can be lowered.

  4B, first, a gate insulating film 6 made of silicon nitride (SiN), a semiconductor active film made of amorphous silicon (a-Si), and n-type amorphous silicon doped with impurities. An ohmic low resistance Si film made of (n + a-Si) is sequentially formed. After the film formation, the second photolithography process is performed to form the Si semiconductor active film (corresponding to the Si semiconductor film described above) 7 and the ohmic low-resistance Si film 8 as the constituent elements of the TFT. And patterning.

  As a preferred embodiment, here, a chemical vapor deposition (CVD) method is used, under a substrate heating condition of about 300 ° C., a SiN film is 400 nm as the gate insulating film 6 and a-Si is used as the Si semiconductor active film 7. An n + a-Si film having a thickness of 150 nm and an ohmic low resistance Si film 8 doped with phosphorus (P) as an impurity was sequentially formed to a thickness of 50 nm. Next, after forming a photoresist pattern by a photolithography process, the a-Si film and the n + a-Si film are etched using a dry etching method using a known fluorine-based gas, and then the photoresist pattern is removed. Then, semiconductor patterns (Si semiconductor active film 7 and ohmic low-resistance Si film 8) that are constituent elements of the TFT were formed.

  Subsequently, after the semiconductor pattern is formed, the surface of the ohmic low resistance Si film 8 is oxidized.

  As a preferred embodiment, the surface of the ohmic low resistance Si film 8 was exposed for 3 minutes in an ozone atmosphere by using an ozone oxidation method. As a result of analyzing the surface of the resulting ohmic low resistance Si film 8 by XPS, the surface density of Si—O was 27.8% and the surface density of Si—N was 0%. The surface density may be paraphrased as the abundance ratio of Si—O bonds and Si—N bonds in the surface region of the ohmic low resistance Si film analyzed by the XPS method. In this example, near the surface of the ohmic low-resistance Si film, Si—O bonds are present at 27.8%, Si—N bonds at 0%, and Si—Si bonds at the remaining 72.2%. It represents that it is in an oxygen-containing state. Moreover, as a result of measuring with a spectroscopic ellipsometer, it was confirmed that the oxygen-containing layer was formed with a thickness of 10 nm.

  In the preferred embodiment of the present embodiment, the oxidation-containing layer is formed by the ozone oxidation method, but the present invention is not limited to this manufacturing method, and heat treatment in an atmosphere containing oxygen atoms, gas containing oxygen atoms It has been confirmed by experiments that a desired oxygen-containing layer can be obtained even if plasma treatment using a hydrogen atom or ion implantation of oxygen atoms is employed. Alternatively, the surface of the Si film or the film containing Si as a main component may be oxidized by a process formed by combining these processes.

  Subsequently, in FIG. 4C, after forming an Al alloy film, a third photolithography process is performed to pattern the Al alloy film, and the source electrode 9, the drain electrode 10, the source wiring 12, A source terminal portion 13 and a channel portion 11 of the TFT are formed. The Al alloy film used in this step includes 1) low electrical specific resistance, 2) good contact characteristics with the ohmic low-resistance Si film 8, and 3) a conductive film used for a transmissive pixel electrode ( In the following, it is preferable to use an alloy film having advantages such as good contact characteristics (in particular, low electrical contact resistance) and the like.

As a preferred embodiment, here, an Al—Ni alloy film was formed by a DC magnetron sputtering method using an AlNi alloy target obtained by adding 2 mol% of Ni to Al. As for sputtering conditions at that time, a mixed gas in which N ₂ gas was added at a flow rate of 3 × 10 ⁻⁴ m ³ / h (5 sccm) to an Ar gas flow rate of 2.4 × 10 ⁻³ m ³ / h (40 sccm). The film formation power density is 3 W / cm ² . Under these conditions, an AlNiN film having a thickness of about 200 nm was formed. Next, after forming a photoresist pattern by a photolithography process, the AlNiN film is etched using a known chemical solution of phosphoric acid + nitric acid + acetic acid, and the source electrode 9, the drain electrode 10, the source wiring 12, and the source A pattern of the terminal portion 13 was formed. Next, the exposed portion of the ohmic low resistance Si film 8 between the source electrode 9 and the drain electrode 10 is etched using a known dry etching method containing a fluorine-based gas, and then the photoresist pattern is removed. Thus, the channel portion 11 of the TFT was formed. As in sputtering DC magnetron sputtering method, instead of the mixed gas obtained by adding N ₂ gas to the Ar gas may be a mixed gas obtained by adding N ₂ gas krypton (Kr) gas.

When the composition of this AlNiN film was examined, it was an alloy film containing 2 mol% Ni and 5 mol% N. The specific resistance value was about 15 μΩ · cm immediately after film formation, but after the heat treatment at a temperature of about 300 ° C., the specific resistance value was reduced to about 10 μΩ · cm. It had been. This value is lower than that of a general conventional refractory metal, and the resistance of the source wiring can be lowered. In the above embodiment, a mixed gas of Ar gas and N ₂ gas is used as the sputtering gas, but Kr gas may be used instead of Ar gas. In this case, since defects and stress of the film can be reduced as compared with the case of using Ar gas, the specific resistance can be reduced to about 10 μΩ · cm without applying heat treatment. In addition, even when N is added to the Al film, the gas added at the time of sputtering is not limited to N ₂ gas. For example, a gas containing N such as NH ₃ can be used in the Al film. It is possible to add N. Alternatively, an AlNiN film may be formed by using an AlNiN alloy in which N is added to a sputtering target in advance. In this case, it is not always necessary to use a mixed gas in which N ₂ or N-containing gas is added to Ar gas or Kr gas as a sputtering gas, and an AlNiN film is formed with Ar gas or Kr gas alone. Is possible.

  Subsequently, in FIG. 5D, after the interlayer insulating film 14 is formed as a passivation film, the fourth photolithography process is performed to pattern the interlayer insulating film 14, so that at least the drain electrode 10 is formed. A pixel drain contact hole 15 that penetrates to the surface, a gate terminal contact hole 16 that penetrates to the surface of the gate terminal portion 4, and a source terminal contact hole 17 that penetrates to the surface of the source terminal portion 13 are formed simultaneously.

  In this case, as a preferred embodiment, a silicon nitride SiN film having a thickness of 300 nm is used as the interlayer insulating film 14 under a substrate heating condition of about 250 ° C. using a chemical vapor deposition (CVD) method. Then, a photoresist pattern is formed by a photolithography process, the interlayer insulating film 14 is etched using a dry etching method using a known fluorine-based gas, and then the photoresist pattern is removed. Thus, the pixel drain contact hole 15, the gate terminal part contact hole 16, and the source terminal part contact hole 17 were formed.

  Finally, in FIG. 5E, after forming a transparent conductive film, the transparent conductive film is patterned by performing a fifth photolithography process, so that the pixel drain contact hole 15 is formed. A transparent pixel electrode 18 electrically connected to the lower drain electrode 10 via the gate terminal pad 19 and the source terminal pad electrically connected via the gate terminal contact hole 16 and the source terminal contact hole 17, respectively. 20 patterns are formed.

  In this manner, an active matrix TFT substrate suitably used for the liquid crystal display device application according to the present embodiment is completed.

  In addition, you may heat-process with the temperature within the range of about 200 to 300 degreeC with respect to the completed TFT substrate. By such heat treatment, static charges and stresses accumulated on the entire TFT substrate are removed or alleviated, and the electrical specific resistance of the metal film can be further lowered, so that the TFT characteristics can be improved and stabilized. It is preferable to perform the said heat processing at the point which can be performed.

As a preferred embodiment, here, as the transparent conductive film, an ITO film in which indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) are mixed is formed to a thickness of 100 nm by sputtering using a known Ar gas. Then, a film is formed. After the ITO film is formed, a photoresist pattern is formed using a photolithography process, and the ITO film is etched using a solution containing a known hydrochloric acid + nitric acid. Electrode 18, gate terminal pad 19 and source terminal pad 20 were formed. Thereafter, the TFT substrate was held in the atmosphere at a temperature of about 300 ° C. for 30 minutes to heat-treat the TFT substrate.

  In the TFT array substrate completed in this way, a film containing Si as a main component and a source electrode 9 and a drain electrode 10 made of an Al alloy film are directly connected. Specifically, the ohmic low-resistance Si film 8 mainly composed of Si and the Al alloy film as the source electrode 9 and the drain electrode 10 are not interposed through the refractory barrier metal layer made of a refractory metal material. Formed by direct connection. Here, in the present specification, the “film containing Si as a main component” refers to a Si film or a film containing Si as a main component, that is, the Si content ratio being the highest. The term “near the interface or near the connection interface” refers to a region closer to the boundary surface than at least half of the film thickness, depending on individual conditions such as the film thickness. Further, the connection between the film containing Si as a main component and the Al alloy film may be in a state where at least a part of the surface of the film containing Si as a main component and at least a part of the Al alloy film are connected. .

  Although the TFT array substrate according to the present embodiment does not include a barrier metal layer made of a refractory metal material, it exhibits the same TFT characteristics as when a conventional refractory metal material is used as a barrier metal layer. It was. This is because, by adding N to the Al—Ni alloy film (formation of an AlNiN alloy film), a Ni-containing layer exists at the bonding interface between Al atoms and Si atoms, and the mutual interaction between Al atoms and Si atoms occurs. The diffusion reaction is suppressed and does not occur, and the Al—Ni alloy film and the Si film are formed in the presence of O atoms combined with Si atoms formed by the oxidation treatment of the surface of the ohmic low resistance Si film 8. Since the direct bonding has allowed O atoms to be contained in the bonding interface between the Al—Ni alloy film and the Si film, the interdiffusion reaction between the Ni atoms and the Si atoms was suppressed and did not occur. It is. Moreover, even when the heat treatment temperature of the TFT array substrate was raised to 300 ° C., no diffusion reaction was observed at the connection interface between the AlNiN alloy film and the Si film, and the TFT characteristics were not deteriorated. Therefore, it was confirmed that the TFT array substrate of the present embodiment has sufficient heat resistance.

(Embodiment 2)
In this embodiment mode, an active matrix TFT substrate for a liquid crystal display device using liquid crystal as a display element is described. An example having a configuration different from that of Embodiment Mode 1 is described below.

  FIG. 6 is a plan view showing the planar structure, and FIG. 7 is a longitudinal sectional view showing the structure such as the AA section of FIG. While the first embodiment relates to an all-transmissive display that performs display by transmitting all the light emitted from the backlight unit and introduced into the liquid crystal, this embodiment is a part of the drain electrode. Relates to a transflective or partially reflective display which also serves as a reflective pixel electrode for reflecting light. Therefore, the source electrode and the drain electrode need to have high surface reflectance characteristics in addition to preventing the interface diffusion reaction with the Si film.

  In FIG. 6 or FIG. 7, the components having the same reference numerals as those in FIG. 2 and FIG. 3 are the same, and thus the description of such components is omitted. The source electrode 9 and the drain electrode 10 are each made of an Al alloy film, and are both directly connected to the ohmic low resistance Si film 8. The channel portion 11 of the TFT is configured in a region where the source electrode 9 and the drain electrode 10 are separated, and the ohmic low-resistance Si film 8 portion between the source electrode 9 and the drain electrode 10 is removed. The source wiring 12 is a wiring connected to the source electrode 9, and the source terminal portion 13 is connected to the source wiring 12 and inputs a video signal from the outside. In FIG. 7, the boundary between the source electrode 9 and the source wiring 12 is not clearly shown. The reflective pixel electrode 21 is an electrode formed extending from the drain electrode 10. The higher the reflectance of the surface of the reflective pixel electrode 21, the brighter and higher quality display characteristics can be obtained. Therefore, the Al alloy film forming each of the source electrode 9, the drain electrode 10, the reflective pixel electrode 21, the source wiring 12, and the source terminal portion 13 has good contact characteristics with the lower ohmic low-resistance Si film 8. It is composed of at least a two-layer film of a 1Al alloy film and a second Al alloy film disposed on the first Al alloy film and having a high reflectance. Specifically, the first Al alloy film is an electrode or wiring indicated by reference numerals 9a, 10a, 12a, 13a, and 21a, and the second Al alloy film is indicated by reference numerals 9b, 10b, 12b, 13b, and 21b. Electrode or wiring.

  As shown in FIG. 7, a plurality of openings (three in FIG. 7) are provided in the interlayer insulating film 14. Among them, the pixel drain contact hole 15 is an opening that reaches the reflective pixel electrode 21 that also serves as the drain electrode 10 in the lower layer. The gate terminal contact hole 16 is an opening that reaches the gate terminal 4. The source terminal contact hole 17 is an opening that reaches the source terminal 13.

  The transmissive pixel electrode 18 is made of a transparent conductive film connected to the reflective pixel electrode 21 through the pixel drain contact hole 15.

  The gate terminal pad 19 is a pad connected to the gate terminal portion 4 via the gate terminal portion contact hole 16. The source terminal pad 20 is a pad connected to the source terminal unit 13 through the source terminal unit contact hole 17.

  The active matrix TFT substrate having the above configuration is bonded to a counter substrate (not shown) including a color filter for color display, a counter electrode, and the like via a certain gap (cell gap). By injecting and sealing the liquid crystal in this, a semiconductor device which is an electro-optical display device for display use is manufactured.

  Next, the manufacturing procedure of the active matrix TFT substrate according to the present embodiment will be described based on FIGS. 8A to 8C and FIGS. 9D to 9E.

  In FIG. 8A, first, the transparent insulating substrate 1 such as a glass substrate is cleaned using a cleaning liquid or pure water, and a metal film is formed on the transparent insulating substrate 1. By patterning the metal film by a photolithography process, the gate electrode 2, the gate wiring 3, the gate terminal portion 4 and the auxiliary capacitance electrode 5 are formed. As the metal film, it is preferable to use a metal or alloy having a low electrical specific resistance.

As a preferred embodiment, first, an AlNi alloy film containing 1 mol% of Ni is formed with a thickness of about 200 nm by a known sputtering method using Ar gas or Kr gas. Regarding sputtering conditions, a DC magnetron sputtering method was used, an AlNi alloy target containing 1 mol% of Ni in Al, a film formation power density of 3 W / cm ² , an Ar gas flow rate of 2.4 × 10 ⁻³ m ³ / h ( An AlNi alloy film was formed under the condition of 40 sccm). Next, after forming a photoresist pattern by a photolithography process, the AlNi alloy film was etched using a chemical solution of a known phosphoric acid + nitric acid + acetic acid system. Then, the pattern of the gate electrode 2, the gate wiring 3, the gate terminal portion 4, and the auxiliary capacitance electrode 5 was formed by removing the photoresist pattern. At this time, the Ni composition of the formed AlNi alloy film was 1 mol% Ni which is almost the same as the target composition. In addition, the specific resistance value was about 8 μΩ · cm immediately after the film formation, but it is possible to reduce the specific resistance value to about 4 μΩ · cm by performing a heat treatment at about 300 ° C. is there. This value is lower than that of a general conventional refractory metal, and has an effect of reducing the resistance of the gate wiring 3.

  Next, in FIG. 8B, first, a gate insulating film 6 made of silicon nitride (SiN), a Si semiconductor active film 7 made of amorphous silicon (a-Si), and an n-type doped with impurities. An ohmic low resistance Si film 8 made of amorphous silicon (n + a-Si) is sequentially formed. After the film formation, the semiconductor active film 7 and the ohmic low-resistance Si film 8 are patterned and formed into a shape serving as a component of the TFT by a second photolithography process.

  As a preferred embodiment, here, a chemical vapor deposition (CVD) method is used, under a substrate heating condition of about 250 ° C., a SiN film is 400 nm as the gate insulating film 6, and a-Si is used as the semiconductor active film 7. An n + a-Si film having a thickness of 150 nm and an ohmic low resistance Si film 8 doped with phosphorus (P) as an impurity was sequentially formed to a thickness of 50 nm. Next, after forming a photoresist pattern by a photolithography process, the a-Si film and the n + a-Si film are etched using a known dry etching method using a fluorine-based gas to remove the photoresist pattern. Thus, semiconductor patterns (semiconductor active film 7 and ohmic low-resistance Si film 8), which are constituent elements of the TFT, were formed.

  Subsequently, after the semiconductor pattern is formed, the surface of the ohmic low resistance Si film 8 is oxidized.

  As a preferred example, an ozone oxidation method was used here, and the exposure was performed for 3 minutes in an ozone atmosphere. As a result of analyzing the surface of the ohmic low resistance Si film 8 by the XPS method, the surface density of Si—O was 27.8%, and the surface density of Si—N was 0%. Moreover, as a result of measuring with a spectroscopic ellipsometer, it was confirmed that an oxygen-containing layer having a thickness of 10 nm was formed.

  In this embodiment, the oxidation-containing layer is formed by the ozone oxidation method. However, the present invention is not limited to this method, and other methods include heat treatment in an atmosphere containing oxygen atoms, and gas containing oxygen atoms. It has been confirmed by experiments that a desired oxygen-containing layer can be obtained even if the plasma treatment used or ion implantation of oxygen atoms is employed. Alternatively, the surface of the Si film or the film containing Si as a main component may be oxidized by a process formed by combining these processes.

  Next, in FIG. 8C, after forming an Al alloy film, a third photolithography process is performed to pattern the Al alloy film, whereby the source electrode 9, the drain electrode 10, A source wiring 12, a source terminal portion 13, and a TFT channel portion 11 are formed. As the Al alloy film used in this step, 1) the advantage of low electrical specific resistance, 2) the advantage of showing good contact characteristics with the ohmic low resistance Si film 8, and 3) the conductive film used for the transmissive pixel electrode 18 4) Use of an alloy film having advantages such as high light reflectivity, in addition to the advantage of showing good contact characteristics (in particular, low electrical contact resistance). Is preferred.

As a preferred embodiment, here, an Al alloy film was formed by using a DC magnetron sputtering method using an AlNi alloy target in which 2 mol% of Ni was added to Al. Regarding sputtering conditions, a mixed gas in which N ₂ gas was added at a flow rate of 1.2 × 10 ⁻³ m ³ / h (20 sccm) to an Ar gas flow rate of 2.4 × 10 ⁻³ m ³ / h (40 sccm) was used. The film forming power density was 3 W / cm ² , and an AlNiN film having a thickness of about 50 nm was formed under these conditions. Next, the addition of N ₂ gas is stopped (flow rate: 0 m ³ / h), only Ar gas is used, and an AlNi film having a film forming power density of 3 W / cm ² and no N is added. Was formed on the upper surface of the AlNiN film. Next, after forming a photoresist pattern by a photolithography process, the upper-layer AlNi / lower-layer AlNiN bilayer film is collectively etched using a known chemical solution of phosphoric acid + nitric acid + acetic acid to form the source electrode 9b / 9a, drain electrode 10b / 10a, source wiring 12b / 12a, source terminal portion 13b / 13a, and reflective pixel electrode 21b / 21a were formed. Then, the exposed portion of the ohmic low resistance Si film 8 between the source electrode 9b / 9a and the drain electrode 10b / 10a is etched using a known dry etching method containing a fluorine-based gas, and then the photoresist pattern is formed. The TFT channel portion 11 was formed by removing the TFT. Note that a mixed gas obtained by adding a gas containing N atoms to Kr gas may be used as a sputtering gas in the DC magnetron sputtering method.

  When the composition of the lower AlNiN film in the above two-layer film was examined, it was an alloy film containing 2 mol% Ni and 20 mol% N. The specific resistance value is about 55 μΩ · cm immediately after the film formation, but after the heat treatment at a temperature of about 300 ° C., the specific resistance value is about 50 μΩ · cm. It was. This value is equal to or higher than that of a general conventional refractory metal, and there is no effect of low resistance. However, the upper AlNi film has a Ni composition of 2 mol%, and its specific resistance is about 8 μΩ · cm immediately after the film formation, and about 4 μΩ · cm after the heat treatment at a temperature of about 300 ° C. cm. Therefore, by forming a two-layer film of upper layer AlNi / lower layer AlNiN, it is possible to reduce the resistance of the source wiring 12 as compared with the case of using a conventional refractory metal. Also, the reflectance value of light measured with light having a wavelength of 550 nm was 70% in the lower AlNiN film, but 93% in the upper AlNi film, and the two-layer film was equivalent to pure Al. It had a high light reflectance value. In this way, when the Al alloy film is formed of a laminated film of at least two layers, the function of preventing the interfacial diffusion reaction with the Si film or a film containing Si as a main component, a low specific resistance value, and a high light The source electrode 9 and the drain electrode 10 and the like can be configured by separating the function of the reflectance value and combining Al alloy films each having optimized characteristics. Therefore, the performance required for the semiconductor device according to this embodiment can be exhibited more effectively, and it can be said that it is preferable to form the Al alloy film with a laminated film of at least two layers.

In the above embodiment, the lower AlNiN film is formed using a mixed gas of Ar gas and N ₂ gas as the sputtering gas, and then the upper AlNi film is switched by switching the sputtering gas to only Ar gas. For example, a lower AlNiN film is formed using a mixed gas of Ar gas and N ₂ gas, and the amount of N ₂ gas added gradually with the progress of sputtering time. It is also possible to reduce the amount. In this case, since the Al alloy film can be continuously formed without interrupting the sputtering process, the processing time for forming the Al alloy film can be shortened. Further, although a mixed gas of Ar gas and N ₂ gas is used as the sputtering gas, Kr gas may be used instead of Ar gas.

  Even in the Al alloy film thus formed, Ni and N exist in the vicinity of the interface with the ohmic low-resistance Si film 8 located in the lower layer of the Al alloy film. N can prevent a mutual diffusion reaction, can reduce the specific resistance value of the entire film, and can obtain a high light reflectance value equivalent to that of a pure Al film.

  Next, in FIG. 9D, after the interlayer insulating film 14 is formed as a passivation film, the interlayer insulating film 14 is patterned by a fourth photolithography process, and at least the drain electrode 10b (reflective pixel) is formed. A pixel drain contact hole 15 that penetrates to the surface of the electrode 21b), a gate terminal contact hole 16 that penetrates to the surface of the gate terminal part 4, and a source terminal contact hole 17 that penetrates to the surface of the source terminal part 13b. Form at the same time.

  As a preferred embodiment, here, a chemical vapor deposition (CVD) method is used, and a silicon nitride SiN film having a thickness of 300 nm is formed as an interlayer insulating film under substrate heating conditions at a temperature of about 300 ° C. Filmed. Then, a photoresist pattern is formed by a photolithography process, the silicon nitride SiN film is etched by using a dry etching method using a known fluorine-based gas, and then the photoresist pattern is removed, A pixel drain contact hole 15, a gate terminal contact hole 16, and a source terminal contact hole 17 were formed.

  Finally, in FIG. 9E, after forming a transparent conductive film, a fifth photolithography process is performed to pattern the transparent conductive film, thereby forming the pixel drain contact hole 15. A transmissive pixel electrode 18 electrically connected to the upper drain electrode 10b (reflective pixel electrode 21b) through the gate terminal and a gate terminal electrically connected through the gate terminal contact hole 16 and the source terminal contact hole 17, respectively. A pattern of pads 19 and source terminal pads 20 is formed. Thus, an active matrix TFT substrate that is suitably used as a liquid crystal display device according to the present embodiment is completed.

  In addition, you may heat-process with respect to the completed TFT substrate in the temperature within the range of about 200 to 300 degreeC. By this heat treatment, static charges and stress accumulated in the entire TFT substrate are removed or alleviated, and the electrical resistivity of the metal film can be further reduced. Therefore, the heat treatment is preferable in that the TFT characteristics can be improved and stabilized.

As a preferred embodiment, here, an ITO film in which indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) are mixed as a transparent conductive film is formed to a thickness of 100 nm by sputtering using a known Ar gas. After forming a film with a thickness, a photoresist pattern is formed using a photolithography process, the ITO film is etched using a solution containing a known hydrochloric acid + nitric acid, and then the photoresist pattern is removed. A transmissive pixel electrode 18, a gate terminal pad 19, and a source terminal pad 20 were formed. Thereafter, the TFT substrate was held in the atmosphere at a temperature of about 300 ° C. for 30 minutes to heat-treat the TFT substrate.

  The TFT array substrate thus completed is directly connected to the ohmic low-resistance Si film 8 without going through the ohmic low-resistance Si film 8 mainly composed of Si and the barrier metal layer made of a refractory metal material. A source electrode 9 and a drain electrode 10 made of an AlNiN alloy film. Although the AlNiN alloy film is directly connected to the ohmic low resistance Si film 8 without interposing a refractory barrier metal layer as in the prior art, 1) connection of the Al—Ni alloy film By adding N atoms in the vicinity of the interface, a Ni-containing layer exists at the bonding interface between Al atoms and Si atoms, so that no interdiffusion reaction between Al atoms and Si atoms occurs. 2) Through the oxidation treatment of the surface of the ohmic low-resistance Si film 8, the interdiffusion reaction between the Ni atoms and the Si atoms occurs due to the inclusion of O atoms at the bonding interface between the Al—Ni alloy film and the Si film 8. In other words, TFT characteristics equivalent to those obtained when a conventional refractory barrier metal was interposed were obtained.

  Even when the heat treatment temperature of the TFT array substrate is increased to 300 ° C., the mutual diffusion reaction at the connection interface between the AlNiN alloy film forming the source electrode 9 and the drain electrode 10 and the Si film 8 is recognized. In addition, the TFT characteristics were not deteriorated, and it was confirmed that the TFT array substrate has sufficient heat resistance.

  Furthermore, since the upper Al alloy film is an AlNi film without adding N on the surface of the Al alloy film opposite to the connection interface, the light reflectance of the reflective pixel electrode 21 (21b / 21a) is high and bright. A high-quality transflective display can be obtained.

  Furthermore, since the source wiring 12 can be formed only of the low resistance Al alloy film in addition to the gate wiring 3, it is excellent in that there is no display unevenness and display defect due to signal delay due to the high resistance of the wiring. A large display or a small high-definition display with display quality can be efficiently produced at low cost.

(Modification of Embodiments 1 and 2)
(1) In the first and second embodiments, an ITO (indium oxide + tin oxide) film is used as the transparent conductive film for forming the transmissive pixel electrode 18 and the terminal pads 19, 20. It is not limited to. That is, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), or a mixture thereof may be used as a material for the transparent conductive film. For example, when an IZO film obtained by mixing zinc oxide with indium oxide is used as a transparent conductive film, a weak acid such as oxalic acid is used instead of a strong acid such as hydrochloric acid + nitric acid used in each of the above embodiments. Can be used as an etchant. For this reason, as in each of the first and second embodiments, when an Al alloy film having poor resistance to acid chemicals is used as the metal film, disconnection corrosion of the electrodes and wiring of the Al alloy film due to the penetration of the chemicals is prevented. Therefore, it can be said that the use of the IZO film is preferable in this respect.

(2) If the sputtered films of indium oxide, tin oxide, and zinc oxide each have a lower oxygen composition than the stoichiometric composition and the properties such as transmittance and specific resistance are poor, Ar gas is used as the sputtering gas. In addition, it is preferable to form the transparent conductive film using a gas mixed with O ₂ gas or H ₂ O gas. In particular, when Ar gas as a sputtering gas is mixed with H ₂ O gas, even when ITO is used as the transparent conductive film, it is not an ordinary polycrystal but an amorphous state. In this case, since the ITO film can be formed, it is possible to etch the ITO film using an oxalic acid-based weak acid chemical solution. This amorphous ITO film can be polycrystallized by, for example, performing a heat treatment at 200 ° C. or higher after the etching process, so that a normal ITO film having high chemical resistance can be obtained. However, it is preferable.

  (3) In each of the first and second embodiments, an Al-1 mol% Ni-20 mol% N film is used as the Al alloy film directly connected to the Si film or the Si film containing Si as a main component. Although an example in which an Al-2 mol% Ni-5 mol% N film is applied has been shown, the present invention is not limited thereto.

  (4) In addition, regarding the method of manufacturing a semiconductor device according to the first and second embodiments, Ni atoms are added after performing a process of oxidizing and nitriding the surface of the Si film or the Si film containing Si as a main component. An AlNi alloy film is formed on the upper surface of the Si film or Si-based Si film so that the AlNi alloy film thus formed is directly bonded to the Si film or Si-based Si film. Also good.

  (5) Alternatively, after forming a Si film or a Si film containing Si as a main component, an Al alloy film containing Ni atoms, O atoms, and N atoms is used, and the Al alloy film contains a Si film or Si as a main component. It is good also as forming on the upper surface of the said Si film or Si film which has Si as a main component so that it may join directly to Si film. For example, by using an aluminum alloy target containing Ni atoms, a sputtering method using a mixed gas obtained by adding a gas containing O atoms and N atoms to argon (Ar) gas or krypton (Kr) gas, Ni atoms, O An Al alloy film containing atoms and N atoms can be formed.

  (6) Alternatively, after forming a Si film or a Si film containing Si as a main component, the surface of the Si film or the Si film containing Si as a main component is subjected to nitriding treatment, and thereafter, Ni atoms and O atoms An Al alloy film containing Ni may be directly formed on the surface of the Si film after nitriding treatment or the Si film containing Si as a main component. In this case, for example, by using a sputtering method using an aluminum alloy target containing Ni atoms and a mixed gas obtained by adding a gas containing O atoms to argon (Ar) gas or krypton (Kr) gas, Ni atoms and O atoms An Al alloy film containing may be formed.

(Analysis and evaluation)
FIG. 10 is a diagram showing an element distribution near the interface between the Al alloy film and the Si film. Among these, FIG. 10A shows the element distribution state in the vicinity of the interface between the Al-2 mol% Ni-10 mol% N film and the oxidized Si film. On the other hand, FIG. 10B shows the element distribution state in the vicinity of the interface between the Al-2 mol% Ni-10 mol% N film and the Si film. FIG. 10 shows the result of examining the element distribution state using Auger electron spectroscopy (AES).

  Referring to FIG. 10B, the Ni atoms contained in the Al—Ni alloy film to which N is added increase in the vicinity of the interface with the Si film, and the interdiffusion at the interface between the Al atoms and the Si atoms is suppressed. That is, it is understood that the slope of the distribution of each of Al atoms and Si atoms at the interface is steeper. Therefore, it is considered that Ni atoms in the Al film move to the vicinity of the interface to form a barrier layer having a high Ni concentration at the interface, thereby suppressing interfacial diffusion between Al atoms and Si atoms.

  On the other hand, referring to FIG. 10A, in the vicinity of the interface between the Al-Ni alloy film to which N is added and the oxidized Si film, the Si film is not oxidized as compared with the case of FIG. 10B. As a result, the presence of O atoms is increasing, and the mutual diffusion of Ni atoms and Si atoms is also suppressed, that is, the slopes of the distributions of Ni atoms and Si atoms at the interface become steeper. I know that. Accordingly, by adding O atoms in the vicinity of the interface between the Al-Ni alloy film to which N atoms are added and the Si film to be oxidized, a barrier layer having a high O concentration is formed at the above interface, so that Ni atoms and Si atoms are reduced. It is considered that interdiffusion is suppressed.

  Since the effect of the barrier layer having a high Ni concentration depends on the apparatus for forming the Al alloy film and the process conditions of the film formation, the film thickness to be formed and the composition of Ni and N to be added are required for the device. What is necessary is just to determine arbitrarily within the range with which the characteristic specification value satisfy | filled. However, in order to fully exhibit the effect of such a high Ni concentration barrier layer, the thickness of the Al alloy film is at least 5 nm, the Ni composition ratio is 0.1 mol% or more, and the N composition ratio is 1 mol% or more. It is preferable that

  Next, in order to optimize the barrier layer with a high O concentration, that is, to examine the appropriate amount of O atom and N atom contained in the vicinity of the interface between the ohmic low resistance Si film and the Al alloy film, Evaluation was performed using the example shown in (4) of the modification. Specifically, after performing an oxidation process and a nitriding process on the surface of the ohmic low resistance Si film, a TFT in which an AlNi alloy film not containing nitrogen is formed on the upper surface of the ohmic low resistance Si film is manufactured. The on and off characteristics were examined.

  Table 1 shows the surface density of Si atoms (Si-O) bonded to O atoms on the surface of the ohmic low resistance Si film 8 subjected to oxidation treatment and nitriding treatment, and Si atoms (Si-N) bonded to N atoms. The change of the on characteristic and the off characteristic of the TFT with respect to the surface density is shown. Both the source electrode and drain electrode of the TFT use an AlNi film that does not contain nitrogen. This AlNi film is an Al alloy film containing 2 mol% of the Ni composition. The on and off characteristics of a TFT are expressed as a ratio based on the on and off current values of a TFT using a Cr metal as a source and drain electrode (hereinafter referred to as a Cr metal TFT) as a conventional high melting point barrier metal layer. Has been. That is, if the on-characteristic is 1 or more and the off-characteristic is 1 or less, the characteristic is better than that of a conventional TFT having a high melting point barrier metal. Further, the on-current value and the off-current value of the TFT after the heat treatment for holding the TFT substrate for 30 minutes at a temperature of 300 ° C. in the atmosphere were measured. Regarding the on-current deterioration (decrease) after the heat treatment, the case where the on-current value after the heat treatment was 80% or more (within 20% reduction) of that before the heat treatment was evaluated as pass (◯). Further, regarding the off-current deterioration (increase) after the heat treatment, it was evaluated as a pass (◯) when the off-current value after the heat treatment was within one digit increase of that before the heat treatment.

  In Table 1, the overall evaluation is No. 10-No. Each of the 16 samples is an example of the present invention in which the interface between the Al alloy film and the oxidized ohmic low resistance Si film 8 satisfies the preferred requirements of the present invention. On the other hand, the overall evaluation is No. 1, no. 8, no. 9 and no. 21-No. Each of the 23 samples is a comparative example that does not satisfy the preferred requirements of the present invention.

In addition, the comprehensive evaluation No. 2-No. Each sample of No. 7 has a good on characteristic and its heat resistance due to the oxidation treatment of the surface of the ohmic low resistance Si film 8, but is a reference example in which the off characteristic has a large heat deterioration due to the lack of N atoms. In this case, as in the first embodiment of the present invention, the AlNi alloy film is formed as an AlNiN film containing N atoms by sputtering using a mixed gas of Ar gas and N ₂ gas, thereby including N atoms. By satisfying the requirements, the preferable requirements of the present invention can be satisfied.

  As described above, Table 1 shows a TFT manufactured by oxidizing and nitriding the surface of the ohmic low resistance Si film and forming an AlNi alloy film not containing nitrogen on the upper surface of the ohmic low resistance Si film. This shows the results of the on characteristic and the off characteristic. Therefore, even if the overall evaluation is a comparative example of ×, by forming an AlNiNO film by sputtering using a gas in which Ar gas, N2 gas, and O2 gas are appropriately mixed when forming the AlNi alloy film, No . 10-No. As shown in FIG. 16, a suitable interface including the Si—N amount and the Si—O amount can be satisfied.

  FIG. 11 shows that in Table 1, No. N with almost no N atoms present on the surface of the ohmic low resistance Si film. 1-No. In each of the ten samples, the relationship of the on-current ratio to the Si-O abundance ratio is shown. O atoms have the effect of suppressing the compound reaction and interdiffusion reaction between Al atoms and Ni atoms of the AlNi alloy film and Si atoms of the ohmic low-resistance Si film, and increasing the on-current value. As the amount of O atoms is increased, the on-current ratio tends to decrease because Al atoms and O atoms are combined at the interface to form a high resistance layer of aluminum oxide. In order to obtain an on-current value (on-current ratio is 1) equal to or higher than that of the reference Cr metal TFT, it is preferable that the Si—O abundance ratio be 45% or less. Further, as can be seen from Table 1, when the abundance ratio of Si—O is 13%, the decrease in the on-current value after the heat treatment becomes large. Accordingly, the abundance ratio of Si—O is preferably at least about 15% or more.

  12 shows that in Table 1, No. in the case of further containing N atoms (Si—N) under the condition that the abundance ratio of Si—O is 15% or more and 45% or less. 7 and no. 9-No. 20, No. containing no N atom. 2-No. 6 shows the relationship of the on-current ratio with respect to the Si—N / Si—O ratio for each of the 6 samples. As can be seen from FIG. 12, when the Si-N / Si-O ratio exceeds 1, the on-current value is lower than the on-current value (on-current ratio = 1) of the reference Cr metal TFT. . Therefore, the Si—N / Si—O ratio is preferably 1 or less. On the other hand, as can be seen from Table 1, when the Si—N abundance ratio is several percent (3, 4%), the decrease in off-current value after heat treatment becomes large. Sample No. 10-No. With reference to 16 Invention Examples 1 to 7, the Si—N abundance ratio is preferably at least about 10% or more.

Referring to the results of the surface density of the ohmic low resistance Si film 8 corresponding to the accepted sample shown in Table 1, FIG. 11 and FIG.
1) Si—O surface density is in the range of 15% to 45%,
2) The abundance ratio (Si—N) / (Si—O) of Si atoms bonded to N atoms (Si—N) and Si atoms bonded to O atoms (Si—O) is 1 or less, and ,
3) It is a feature of the present invention that the Si-N surface density is 10% or more.

(Summary)
As described above, according to the first and second preferred embodiments of the present invention, the Al alloy film that realizes good contact characteristics by directly connecting to the Si film or the film mainly composed of Si, and The manufacturing method can be provided. As a result, in a semiconductor device having at least a structure in which the Al alloy film is directly connected to the Si film or a film containing Si as a main component, the Al alloy film and the Si alloy can be formed without interposing a refractory barrier metal. Good contact characteristics with a film or a film containing Si as a main component can be obtained. More specifically, a TFT source having good contact characteristics with an oxide transparent conductive film such as an ITO film and a Si film or a film containing Si as a main component and heat resistance as a TFT. It is possible to provide an Al alloy film forming an electrode and a drain electrode. Therefore, it is possible to efficiently manufacture a semiconductor device at a low cost, and an improvement in yield in manufacturing the semiconductor device is also expected.

  Further, since the conventional intervention of the refractory barrier metal is eliminated, the width of the metal wiring such as the source wiring or the drain electrode wiring can be reduced. Miniaturization can be achieved.

  In addition, since the conventional high melting point barrier metal is not required, when the width of the metal wiring such as the source wiring is set as usual, the metal wiring such as the source wiring or the drain electrode wiring is reduced. Since resistance can be realized, as a result, low power consumption (energy saving) of the semiconductor device can be achieved.

  Further, the necessity of the intervention of the conventional high melting point barrier metal brings about the ease of disassembling the present semiconductor device.

  Further, when the conventional high melting point barrier metal is an alloy containing Cr as a main component, there is an advantage that the use of harmful Cr can be eliminated.

  In addition, by applying the Al alloy film of each of the first and second embodiments to the source electrode and drain electrode of the active matrix TFT substrate for display and wiring such as source wiring, the wiring resistance can be reduced, A TFT element having good on-characteristics, off-characteristics and heat resistance characteristics can be formed only by the Al alloy film described above. Therefore, even in a large display or a small high-definition display, it is possible to efficiently produce a display with high display quality free from display unevenness and display defect due to signal delay or the like at low cost. In this way, a display device requiring low resistance wiring can be manufactured with high production capacity.

(Appendix)
Although the embodiments of the present invention have been disclosed and described in detail above, the above descriptions are examples of the applicable aspects of the present invention, and the present invention is limited to the contents of the embodiments. is not. That is, various modifications or variations to the described aspects can be considered without departing from the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 Transparent insulating substrate, 2 Gate electrode, 3,43 Gate wiring, 4 Gate terminal part, 5 Auxiliary capacity electrode, 6 Gate insulating film, 7 Si semiconductor (active) film, 8 Ohmic low resistance Si film, 9 Source electrode, 10 drain electrode, 11 TFT channel part, 12, 44 source wiring, 13 source terminal part, 14 interlayer insulating film, 15 pixel drain contact hole, 16 gate terminal part contact hole, 17 source terminal part contact hole, 18 transmissive pixel electrode, 19 gate terminal pad, 20 source terminal pad, 21 reflective pixel electrode, 41 display area, 42 frame area, 45 scanning signal drive circuit, 46 display signal drive circuit, 47 pixel, 48, 49 external wiring.

Claims (16)

A film mainly composed of Si;
An aluminum alloy film directly bonded to the Si-based film;
In the vicinity of the bonding interface between the Si-based film and the aluminum alloy film, at least Ni atoms, O atoms, and N atoms are included.
Semiconductor device. The semiconductor device according to claim 1,
The Si-based film is an ohmic resistance film including Si—O which is Si atom bonded to the O atom and Si—N which is Si atom bonded to the N atom in the vicinity of the bonding interface. It is characterized by
Semiconductor device. The semiconductor device according to claim 2,
Regarding the surface density of the Si-based film, the surface density of the Si—O is in the range of 15% to 45%, and the abundance ratio of the Si—N and the Si—O (Si—N). / (Si—O) is 1 or less, and the surface density of the Si—N is 10% or more,
Semiconductor device. A semiconductor device according to any one of claims 1 to 3,
The aluminum alloy film contains the Ni atoms only in the vicinity of the bonding interface,
Semiconductor device. A semiconductor device according to any one of claims 1 to 4,
The aluminum alloy film includes the Ni atoms only in the vicinity of the bonding interface, and also includes the O atoms and the N atoms in the vicinity of the bonding interface.
Semiconductor device. The semiconductor device according to claim 5,
The abundance ratio N / O between the N atoms and the O atoms contained in the aluminum alloy film is 1 or less,
Semiconductor device. The semiconductor device according to claim 1, comprising the semiconductor device according to claim 1.
Display device. Forming a film containing Si as a main component;
A step of directly bonding to the Si-based film and forming an aluminum alloy film so as to include Ni atoms, O atoms, and N atoms in the vicinity of a bonding interface bonded to the Si-based film. Characterized by comprising
A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device according to claim 8, comprising:
The aluminum alloy film forming step includes
Oxidizing and nitriding the surface of the Si-based film;
A step of forming the aluminum alloy film containing Ni atoms so as to be directly bonded to a film containing Si as a main component after being subjected to the oxidation treatment and the nitriding treatment.
A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device according to claim 8, comprising:
The aluminum alloy film forming step includes
Oxidizing the surface of the Si-based film;
A step of forming the aluminum alloy film containing the Ni atoms and the N atoms so as to be directly bonded to the film having Si as a main component after oxidation of the surface,
A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device according to claim 10, comprising:
The step of forming the aluminum alloy film containing the Ni atoms and the N atoms includes sputtering using a mixed gas obtained by adding a gas containing N atoms to argon gas or krypton gas using an aluminum alloy target containing Ni atoms. Characterized by the law,
A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device according to claim 8, comprising:
The aluminum alloy film forming step includes
Nitriding the surface of the film containing Si as a main component;
A step of forming the aluminum alloy film containing the Ni atoms and the O atoms so as to be directly bonded to the film containing Si as a main component after the nitriding treatment.
A method for manufacturing a semiconductor device. A method of manufacturing a semiconductor device according to claim 12,
The step of forming the aluminum alloy film containing Ni atoms and O atoms uses a mixed gas obtained by adding a gas containing O atoms to argon gas or krypton gas using the aluminum alloy target containing Ni atoms. It is characterized by the sputtering method,
A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device according to claim 8, comprising:
The aluminum alloy film forming step includes
A step of forming the aluminum alloy containing the Ni atom, the O atom and the N atom so as to be directly bonded to the Si-based film;
A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device according to claim 14, comprising:
The step of forming the aluminum alloy including the Ni atom, the O atom, and the N atom includes the O atom and the N atom in argon gas or krypton gas using the aluminum alloy target including the Ni atom. It is a sputtering method using a mixed gas with added gas,
A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device according to any one of claims 8 to 15,
The step of forming the film containing Si as a main component includes:
Heat treatment in an atmosphere containing O atoms, plasma treatment using a gas containing O atoms, ion implantation of O atoms, or exposure to an atmosphere containing ozone, or a combination of these processes Characterized by comprising the following steps:
A method for manufacturing a semiconductor device.

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