JP4394466B2 - Method of manufacturing array substrate capable of preventing copper diffusion - Google Patents

Description

The present invention relates to manufacturing method of an array substrate used in a liquid crystal display panel or the like.

  The liquid crystal display panel is formed by sealing liquid crystal between an opposing array substrate and a color filter substrate. In an active matrix type liquid crystal display panel which has been mainstream in recent years, gate lines and signal lines cross on an array substrate and are wired in parallel. In addition, a thin film transistor (TFT) is disposed at the intersection of the two.

  At present, gate lines and signal lines of an array substrate are generally formed of a metal mainly composed of Al or an Al alloy, and Mo / Al-alloy or pure Al is an phosphoric acid / nitric acid / acetic acid-based etchant. The method of processing into a taper shape using the mainstream has become the mainstream.

  In recent years, with the high definition and large screen of the panel, wiring resistance and parasitic capacitance have increased, and the problem of wiring delay has become apparent. In order to reduce the problem of wiring delay, it is effective to lower the wiring resistance. However, at present, the only way to prevent the aperture ratio from decreasing is to increase the wiring film thickness, and there is a problem of a decrease in yield due to the deterioration of the coating of the CVD insulating film.

  The realization of a wiring material using Cu, which is a further low-resistance material, is awaited. However, as major issues, 1) establishment of a method for suppressing Cu diffusion, 2) improvement of adhesion to the substrate, and 3) forward taper. Establishment of a patterning method to be used.

  The suppression method 1) is necessary, for example, for preventing Cu from diffusing into amorphous Si constituting the TFT and degrading the performance of the semiconductor. Further, the adhesion between the substrate 2) means, for example, adhesion between a glass substrate and Cu which is a core metal of the wiring.

  Further, when Cu is used for the core metal of the wiring unlike the conventional Mo / Al-alloy, the etching rate of Cu is faster than that of Mo. Therefore, the cross section of the wiring pattern has an upper Mo layer as shown in FIG. Easy to stand up to. For this reason, the coverage when the wiring is covered with a subsequent insulating layer or the like is lowered, which may cause a product defect. Accordingly, it is necessary to establish a patterning method for the forward taper of 3) above.

  Patent Document 1 discloses a method of suppressing diffusion of Cu by forming an alloy layer of W, Re, or both and Ni on the upper layer of Cu. However, since the alloy layer is formed by plating, it is difficult to form a thin film with a thickness of about several hundreds and a small surface roughness, and there is a problem in consistency with the subsequent liquid crystal display manufacturing process.

  A three-layer structure such as Ta / Cu / Ta has already been devised. The upper layer Ta is used as a diffusion barrier film for contact metal and Cu, and the lower layer Ta is used as an adhesion layer to glass. However, the etching of Ta and Cu becomes multi-stage etching of dry-wet-dry, and problems remain in productivity and wiring shape.

JP 2003-353222 A ([23] to [31])

  Therefore, an object of the present invention is to provide an array structure that has a high adhesion with a substrate, a low resistance value, and a high Cu diffusion preventing effect by a simple etching process.

Do拡 distributed array substrate capable of preventing a consists substrate and a copper wiring formed on the substrate, which is laminated to cover the top and sides of the copper wire, a metal or metal nitride layer diffusion An anti-diffusion layer, and the anti-diffusion layer prevents diffusion of copper in the copper wiring.

Do拡 distributed array substrate capable of preventing the includes a substrate and, formed on the substrate, an adhesion layer made of a metal or a metal nitride film, and a copper wiring formed on the substrate, an upper portion of the copper wiring And a diffusion prevention layer made of a metal or a metal nitride film, which is laminated so as to cover the side portions. In addition, since the said copper wiring coat | covers the upper part and side part of the said copper wiring with a diffusion prevention layer, it is preferable that a cross section is a taper shape.

In this specification, the copper wiring means copper or wiring containing copper as a main component, and includes the diffusion prevention layer and / or the adhesion layer that covers the copper wiring. In the wiring, the copper wiring layer is also referred to as a core metal below.

Do拡 distributed array substrate capable of preventing a, the diffusion barrier layer may be a titanium nitride or molybdenum nitride having an amorphous-like structure.

Do拡 distributed array substrate capable of preventing a, the adhesion layer may be a titanium nitride or molybdenum nitride having an amorphous-like structure.

  The method of manufacturing an array substrate capable of preventing copper diffusion according to the present invention includes a step of preparing a substrate, a step of covering the substrate with an adhesion layer made of a metal or a metal nitride film, and copper on the adhesion layer. Forming a wiring; covering the adhesion layer and the copper wiring formed on the adhesion layer with a diffusion prevention layer made of metal or a metal nitride film; and the diffusion prevention layer remains only on the copper wiring. Patterning.

  In the method of manufacturing an array substrate capable of preventing copper diffusion according to the present invention, the patterning step includes applying a resist on the diffusion prevention layer, and exposing the resist from the back surface of the substrate using the copper wiring as a mask. Developing the resist to form a resist pattern on the copper wiring, and etching the diffusion prevention layer exposed from the resist pattern.

  The method of manufacturing an array substrate capable of preventing copper diffusion according to the present invention may include a step of etching the adhesion layer successively after the step of etching the diffusion prevention layer.

  In the method of manufacturing an array substrate capable of preventing copper diffusion according to the present invention, the diffusion prevention layer or the diffusion prevention layer and the adhesion layer may be titanium nitride having an amorphous-like structure.

  In the method of manufacturing an array substrate capable of preventing copper diffusion according to the present invention, the step of covering with the adhesion layer made of the metal nitride film and / or the step of covering with the diffusion prevention layer made of the metal nitride film is based on the total sputtering gas flow rate. Reactive sputtering with a nitrogen gas flow ratio of 5 to 30 percent may be included.

  In the method of manufacturing an array substrate capable of preventing copper diffusion according to the present invention, the diffusion preventing layer, or the diffusion preventing layer and the adhesion layer may be molybdenum nitride having an amorphous structure.

  The method of manufacturing an array substrate capable of preventing copper diffusion according to the present invention includes the step of covering with the adhesion layer made of the metal or metal nitride film and / or the step of covering with the diffusion prevention layer made of the metal or metal nitride film. Reactive sputtering with a nitrogen gas flow rate ratio to a sputtering gas flow rate of 30 percent or less may be included. When reactive sputtering is performed at a nitrogen gas flow rate ratio of 0% with respect to the total sputtering gas flow rate, the diffusion prevention layer and the adhesion layer in this specification are formed of a single piece of molybdenum having an amorphous-like structure. It is defined as

  The specific resistance of the core metal of the wiring has been greatly improved. Further, even when the wiring has a laminated structure, the sheet resistance is approximately halved. Therefore, by reducing the wiring delay due to the low resistance, it is possible to expect a response to large size and high definition and an improvement in aperture ratio.

  An embodiment of the present invention will be described with reference to FIG. The array substrate capable of preventing copper diffusion according to the present invention is used for a printed circuit board on which copper wiring is formed, particularly a liquid crystal display panel, an organic EL panel, and the like.

  As shown in FIG. 1A, an array substrate 10 capable of preventing copper diffusion according to the present invention includes a substrate 12, an adhesion layer 14 made of a metal or a metal nitride film formed on the substrate 12, and an adhesion layer. It includes a copper wiring 16 formed thereon, and a diffusion prevention layer 18 made of a metal or a metal nitride film laminated to cover the upper and side portions of the copper wiring 16.

  As another embodiment, as shown in FIG. 1 (b), an array substrate 50 capable of preventing copper diffusion according to the present invention includes a substrate 52 and an adhesion made of a metal or metal nitride film formed on the substrate 52. The layer 54, a copper wiring 56 formed on the adhesion layer 54, and a diffusion prevention film 58 that covers and laminates the upper part of the copper wiring 56 may be included.

  For the substrate 12 or 52, glass or the like that transmits light is used. Hereinafter, the substrate 12 or 52 is a glass substrate 12 or 52.

  The adhesion layer 14 or 54, which is a metal film or a metal nitride film, and the diffusion prevention layer 18 or 58 are formed on the lower portion, the upper portion, or both of the copper wiring 16 or 56 by a film formation method such as sputtering. The adhesion layer 14 or 54 is used for the substrate 12 or 52, and the diffusion prevention layer 18 or 58 is used as a diffusion / contamination prevention film for an insulating film formed in a later process or a film forming apparatus thereof, mainly a CVD apparatus.

  The diffusion of copper in the metal forming the copper wiring 16 or 56 is considered to be dominated by grain boundary diffusion. In the array substrate 10 or 50 of the invention, in order to prevent the copper diffusion, a dense amorphous material is used. A diffusion prevention film 16 or 56 having a structure is used. Metal nitride films such as titanium nitride (TiN) and molybdenum nitride (MoN) are effective, and by optimizing their nitrogen content, other electrodes having a minute and dense amorphous structure and specific resistance are available. It is possible to realize the diffusion prevention film 16 or 56 having such a low resistance that it does not cause a problem as a contact layer to the layer.

Hereinafter, using Table 1, the process of coating the metal film on the array substrate 10 of the present invention will be described by dividing it into a pre-process and a post-process.

  The pre-process of the array substrate 10 of the present invention includes (1) a step of preparing and cleaning the glass substrate 12, and (2) covering the substrate 10 with an adhesion layer 14 made of a metal such as MoN or TiN or a metal nitride film. Further, the step of covering the adhesion layer 14 with a copper layer (Cu), (3) the step of applying a resist on the copper layer (Cu), (4) the step of exposing with a mask from the resist side, (5) Developing a resist pattern, (6) wet etching with a PAN-based (phosphoric / acetic / nitric) phosphoric acid / acetic acid / nitric acid etchant, and (7) removing the resist.

  In the step (6), the copper wiring 16 can be obtained by utilizing the isotropy of etching and the adhesion of Cu to the resist.

  The pre-process for the array substrate 10 is substantially the same as the manufacturing process for manufacturing a wiring board made of conventional aluminum (Al) or the like, and it is not necessary to introduce a new apparatus. There are two changes: the sputter film type has changed from Al or AlNd to Cu, and the PAN-based etchant composition for etching the wiring has changed.

  Next, the post-process of the array substrate 10 of the present invention will be described. The post-process includes (8) a step of coating the adhesion layer 14 and the copper wiring 16 formed on the adhesion layer 14 with a diffusion prevention layer 18 made of a metal such as MoN or TiN or a metal nitride film by sputtering, and (9) Diffusion. A step of applying a resist on the prevention layer 18, (10) a backside exposure from the surface side of the glass substrate 12, and subsequently developing, (11) a wet etching step with a PAN-based etchant, and (12) peeling off the resist Including the step of:

  FIGS. 5A, 5B, and 5C are cross-sectional views of the array substrate 10 of the present invention in the above-described steps (8), (10), and (11), respectively. By performing backside exposure and development from the surface side of the glass substrate 12 in the step (10) and wet etching in the step (11), the diffusion prevention layer 18 can be patterned so as to remain only on the copper wiring 16. In other words, in order to completely cover the copper wiring 16 (Cu) with the upper diffusion prevention layer 18, the metal barrier layer, that is, the diffusion prevention layer 18 is patterned by the step (10) using the backside exposure.

  The properties, performance, and the like of the array substrate 10 of the present invention manufactured by the process described above will be described below using experiments described in the examples.

For titanium (Ti) and titanium nitride (TiN), the amount of nitrogen (N ₂ ) added during film formation in reactive sputtering was changed, and structural analysis was performed using a transmission electron microscope (TEM). In the titanium film formed without adding nitrogen, a columnar crystal structure was confirmed as shown in FIG.

Next, in the reactive sputtering, when nitrogen is added to the argon (Ar) gas, the crystal structure changes, and when the ratio of Ar gas to N ₂ gas is 95: 5, the above is obtained as shown in FIG. The columnar crystal structure became blurred. When nitrogen is further added and the ratio of Ar gas to N ₂ gas is set to 70:30, the columnar crystal structure of FIG. 2A disappears, and the amorphous-like dense and fine structure as shown in FIG. The structure was confirmed.

Next, the specific resistance and surface roughness (Rms) of the formed titanium (Ti) and titanium nitride (TiN) are changed by changing the addition amount of nitrogen (N ₂ ) in reactive sputtering in the same manner as in Example 1. It was measured.

  Anti-diffusion layer and adhesion layer have low resistance for contact with the electrode formed in the upper layer or lower layer, interlayer insulation film formed in the upper layer, interlayer insulation of the semiconductor layer, and maintenance of mobility Although the surface roughness is required to be small, as shown in FIG. 3, a film having sufficiently low resistance and high flatness can be realized in the region where the amount of nitriding added is 5 to 30% of the argon ratio.

In Example 3, as a barrier property evaluation, a dielectric breakdown life test was performed under high temperature and high pressure. The experimental conditions were 150 ° C., the area of the cylindrical test substance was 1.346 mm ² , and a 1500 N thick SiN insulating film was sandwiched between the electrode and the test substance. The test substance used was copper (Cu) alone, titanium nitride with a nitrogen addition amount of 30% (N ₂ gas Ar gas ratio 30%), and a (Mo) electrode as a reference. When the copper diffusion into the SiN insulating film is large, the dielectric breakdown life is shortened.

As can be seen from FIG. 4, titanium nitride with a nitrogen addition amount of 30% (30% N ₂ gas argon ratio) exhibits the same performance as the reference (Mo electrode) and has a sufficient anti-diffusion effect. I was able to prove. In this embodiment, an insulating film that can exhibit a relatively high barrier property even with a single copper is used.

On the other hand, although not shown in the figure, the effect of preventing diffusion was not so much expected with titanium nitride with a nitriding addition amount of 5% (N ₂ gas ratio 5%) or less.

Finally, Table 2 shows specific resistances of the conventional Mo / AlNd multilayer structure and the TiN / Cu / Ti multilayer structure according to an embodiment of the present invention. In both structures, the thicknesses of the diffusion prevention layer and the core metal responsible for electrical conduction are 500 mm and 3000 mm, respectively. The thickness of the Ti film, which is an adhesion layer having a TiN / Cu / Ti laminated structure, was 150 mm.

  From Table 2, when the core metal was AlNd, the specific resistance was 4.8 μΩcm, whereas in the case of Cu, it was 2.2 μΩcm. Therefore, the specific resistance of the core metal of the wiring has been greatly improved.

  Further, even when the wiring has a laminated structure, the sheet resistance is approximately halved. In the case of Mo / AlNd wiring, the sheet resistance was 154 mΩ / port, whereas when TiN / Cu / TiN of the laminated structure of the present invention was used, the sheet resistance was 73 mΩ / port.

  The array substrate capable of preventing copper diffusion according to the present invention has been described with reference to the embodiments. However, the array substrate of the present invention is not limited to the above embodiments. The core metal may be formed of a metal mainly composed of Cu, and the diffusion prevention layer and the adhesion layer may be formed of either MoN or TiN. Alternatively, either the diffusion preventing layer or the adhesion layer may be omitted.

  Moreover, although the embodiment of the array substrate capable of preventing copper diffusion of the present invention has been described mainly using the array substrate 10, the array substrate of the present invention is not limited to the above-described embodiment, and the above-described array substrate 50, etc. May also be included.

  In addition, the thickness of each layer in the wiring laminated structure of the array substrate capable of preventing copper diffusion according to the present invention is not limited to the thickness shown in the fourth embodiment. The thickness of each layer is arbitrary, and the above laminated structure taking the thickness ratio of every layer can be included in the present invention.

  The manufacturing process of the array substrate 50 of the present invention is substantially the same as the previous process of the array substrate 10. That is, in the previous step (2) of the array substrate 10 of the present invention, the adhesion layer 5 made of a metal such as MoN or TiN or a metal nitride film is coated, and the adhesion layer 14 is further coated with a copper layer (Cu). A metal such as MoN or TiN or a metal nitride film is further stacked on the copper layer. Thereafter, the array substrate 50 of the present invention shown in FIG. 1B can be obtained through the steps of the preceding steps (3) to (7).

  In addition, the present invention can be carried out in a mode in which various improvements, modifications, and changes are added based on the knowledge of those skilled in the art without departing from the gist thereof.

  It can be used for all printed circuit boards with copper wiring, especially for array boards used in liquid crystal televisions, personal computer displays, and other displays.

(A) It is sectional drawing of the part in which the copper wiring was formed of the array board | substrate which can prevent copper diffusion based on this invention. (B) It is sectional drawing of the part in which the copper wiring in the other form of the array board | substrate which can prevent copper diffusion based on this invention was formed. (A) In reactive sputtering, copper wiring is formed, which is a cross-sectional view showing a structural analysis photograph by a transmission electron microscope (TEM) of a diffusion prevention layer (Ti) formed without adding nitrogen (N ₂ ) It is sectional drawing of the array substrate of the part made. (B) In reactive sputtering, a copper wiring is formed, which is a structural analysis photograph by a transmission electron microscope (TEM) of a diffusion prevention layer (TiN) formed at a ratio of Ar gas to N ₂ gas of 95: 5 It is sectional drawing of the array substrate of the part made. (C) In reactive sputtering, it is a sectional view showing a structural analysis photograph by a transmission electron microscope (TEM) of a diffusion prevention layer (TiN) formed at a ratio of Ar gas to N ₂ gas of 70:30. It is sectional drawing of the array substrate of the part in which the copper wiring was formed. Diffusion preventing layer formed by changing the ratio of Ar gas and N ₂ gas (TiN and Ti), is a graph plotting the measurements of resistivity and surface roughness (Rms). In the dielectric breakdown life test, when the test substance is copper (Cu) simple substance, titanium nitride (TiN; Ar gas ratio of N ₂ gas 30%), molybdenum (Mo) electrode, the dielectric breakdown life of each test substance And a graph plotting the relationship between the electric field strength applied to each test substance. (A) It is sectional drawing of the part in which the copper wiring was formed in the manufacturing process (8) of the array substrate which can prevent the copper diffusion based on this invention. (B) It is sectional drawing of the part in which the copper wiring was formed in the manufacturing process (10) of the array board | substrate which can prevent copper diffusion based on this invention. (C) It is sectional drawing of the part in which the copper wiring was formed in the manufacturing process (11) of the array substrate which can prevent the copper diffusion based on this invention. It is sectional drawing of the wiring pattern which laminated | stacked Mo on the core metal.

Explanation of symbols

10, 50: Array substrate 12, 52: Glass substrate 14, 54: Adhesion layer 16, 56: Copper wiring (core metal)
18, 58: Diffusion prevention layer 20: Resist layer

Claims (6)

Preparing a substrate;
Coating the substrate with an adhesion layer made of a metal or metal nitride film;
Forming a copper wiring on the adhesion layer;
Coating the adhesion layer and the copper wiring formed on the adhesion layer with a diffusion preventing layer made of a metal or a metal nitride film;
Patterning so that the diffusion barrier layer remains only on the copper wiring;
Only including,
The patterning step comprises:
Applying a resist on the diffusion preventing layer;
Exposing the resist from the back surface of the substrate using the copper wiring as a mask;
Developing the resist and forming a resist pattern on the copper wiring;
Etching the diffusion barrier layer exposed from the resist pattern;
A method of manufacturing an array substrate that can prevent copper diffusion. The method of manufacturing an array substrate capable of preventing copper diffusion according to claim 1 , further comprising a step of etching the adhesion layer after the step of etching the diffusion prevention layer. 3. The method of manufacturing an array substrate capable of preventing copper diffusion according to claim 1 , wherein the diffusion prevention layer, or the diffusion prevention layer and the adhesion layer are titanium nitride having an amorphous-like structure. The step of covering with the adhesion layer made of the metal nitride film and / or the step of covering with the diffusion prevention layer made of the metal nitride film,
The method of manufacturing an array substrate capable of preventing copper diffusion according to claim 3 , comprising the step of performing reactive sputtering in which a flow rate ratio of nitrogen gas to total sputtering gas flow rate is 5 to 30 percent. 3. The method of manufacturing an array substrate capable of preventing copper diffusion according to claim 1 , wherein the diffusion prevention layer, or the diffusion prevention layer and the adhesion layer are made of molybdenum nitride having an amorphous-like structure. The step of covering with the adhesion layer made of the metal or metal nitride film and / or the step of covering with the diffusion prevention layer made of the metal or metal nitride film,
Performing reactive sputtering in which the flow ratio of nitrogen gas to the total sputtering gas flow is 30 percent or less,
The manufacturing method of the array board | substrate which can prevent the copper diffusion of Claim 5 .

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