METAL WIRE STRUCTURE WITH HIGH-MELTING-POINT PROTECTIVE LAYER AND ITS MANUFACTURING METHOD

Abstract

The present invention presents a metal wire structure with high-melting-point protective layer and its manufacturing method, of which the structure comprising: a core and a protective layer; the core is made of metal, and the protective layer made of metal carbide or metal nitride. The manufacturing method includes the following steps: preparation, discharge and finish. The protective layer is gradually bonded onto the exterior surface of the core until a preset thickness of the protective layer, and then fully covered onto the core through a plating process of discharge reaction at temperature over 5000□. With this design, the present invention has advantages and efficacies such as: without generation of silicide and producing protective effects.

Description

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates generally to a metal wire structure with high-melting-point protective layer and its manufacturing method, and more particularly to an innovative one which prevents the generation of silicide and produces protective effect.

2. Description of Related Art

The conventional Hot Wire Chemical Vapor Deposition (HWCVD) and Plasma Enhanced Chemical Vapor Deposition (PECVD) are widely applied to the manufacturing processes of various films, including: semi-conductors, liquid crystal display (LCD) panels and solar panels, helping to form a thin film on a substrate. Such film is made of Amorphous Silicon (a-Si) or other components (depending on the reactant gases supplied).

The major disadvantages of PECVD include: low deposition rate, low productivity, longer deposition time and cost. The disadvantages of HWCVD include: difficult to control the concentration of free radical or the filament temperature, and lower film quality.

FIG. 1 depicts a hybrid chemical vapor deposition combining HWCVD and PECVD (patent No. WO 2009/2009499). Of which, a closed reaction chamber 810 comprises: a reaction space 820, a plasma generating unit 830, a hot wire device 840, a substrate 850, a substrate carrier 860, a heater 870, a substrate feeder 875 and a substrate discharger 880. The plasma generating unit 830 is used to generate plasma-excited atoms of vapor chemicals, and the hot wire device 840 is used to generate thermally-excited atoms of vapor chemicals. For instance, the mixture of hydrogen (H₂) and silicon hydride (SiH₄) is fed into the reaction space 820 at 1:100; the hot wire device 840 is heated to 1850° C., the plasma generating unit 830 generates the energy of 25 w/100 cm² for the substrate, and the heater 870 maintains the temperature of 400° C. With the use of HWCVD and PECVD, a-Si film can be generated on the substrate 850.

FIG. 2 depicts another conventional HWCVD technique (patent No. EP1986242A2), which comprises: a reaction chamber 91, a gas feed portion 92, a direct current (DC) power supply 93, a catalytic hot wire 94, an exhaust valve 95, a carrier platform 96 and a heater 97. The carrier platform 96 is provided with a bottom layer 920, which can be heated by the heater 97; a film 910 is gradually formed on the bottom layer 920.

However, both hot wire device 840 and catalytic hot wire 94 are made of pure tungsten; when silicon hydride (SiH₄) is filled into the reaction space 820 and the reaction chamber 91, and the temperature of hot wire device 840 or catalytic hot wire 94 hasn't reached the melting point of silicon (about 1410° C.), the gas will contact with the hot wire device 840 or catalytic hot wire 94, but cannot be fully decomposed, with some residual gas left on the surface of hot wire device 840 or catalytic hot wire 94. Then, the silicide (e.g. tungsten silicide) is formed, leading to change of the filament resistance. Take catalytic hot wire 94, for example, FIGS. 3A and 3B depicts the outside view of the catalytic hot wire 94 without and with silicide respectively, whilst FIGS. 4A and 4B depicts the partially enlarged sectional view of the surface of catalytic hot wire 94 without or with silicide respectively. It can be clearly seen that, when silicide 941 is formed on the surface of the catalytic hot wire 94, silicide 941 may generate many cracks 942 due to expansion and contraction, as the surface temperature of the catalytic hot wire 94 is at normal temperature in idle state, or at 1850° C. in operating state. In addition, when the silicide 941 is fully covered onto the catalytic hot wire 94, the function of the catalytic hot wire 94 will be lost, affecting the process of hot wire chemical vapor deposition seriously.

Hence, it is important to know how to prevent generation of silicide with fed gas when the temperature of tungsten filament (either hot wire device 840 or catalytic hot wire 94) increases from normal temperature to 1850° C.

Thus, to overcome the aforementioned problems of the prior art, it would be an advancement if the art to provide an improved structure that can significantly improve the efficacy.

SUMMARY OF INVENTION

The object of the present invention is to provide a metal wire structure with high-melting-point protective layer and its manufacturing method, which prevents the generation of silicide and produces protective effect to resolve the shortcomings of prior art.

In order to achieve the above mentioned object, this invention is provided. A manufacturing method of metal wire structure with high-melting-point protective layer comprising the following steps:

preparation step: preparing a core and a discharge device, of which the core in a threaded shape is made of metal material; the discharge device being provided with a positive electrode, a negative electrode, a discharge reaction tank, a discharge processing medium, an electrode fixed portion and a discharge reaction member; the discharge processing medium being placed into the discharge reaction tank, the electrode fixed portion being used to fix the core, which is linked to the negative electrode; the discharge reaction member made of metal being linked to the positive electrode; a preset discharge gap being defined between the core and the discharge reaction member, and filled with the discharge processing medium; the discharge processing medium consisting of either carbon atom or nitrogen atom;

discharge step: the discharge device being activated to enable electrical discharge of the core and the discharge reaction member; a local temperature in this discharge process being over 5000° C., so metal atoms of the core impinging dispersedly on an exterior surface of the discharge reaction member, meanwhile the metal atoms of the discharge reaction member being combined with atoms in the discharge processing medium, and impinging dispersedly on the exterior surface of the core, so a protective layer being gradually formed on the exterior surface of the core;

finish step: a metal wire structure with high-melting-point protective layer being made which comprises:

• • a core which is made of metal material and is shaped as a thread;
  • a protective layer which is made of either metal carbide or metal nitride; the protective layer being gradually bonded onto an exterior surface of the core until a preset thickness, and then fully covered onto the core through a plating process of discharge reaction at temperature over 5000° C.

About the structure of this invention, a metal wire structure with high-melting-point protective layer comprises:

a core which is made of metal material and is shaped as a thread;

a protective layer which is made of either metal carbide or metal nitride; the protective layer being gradually bonded onto an exterior surface of the core until a preset thickness, and then fully covered onto the core through a plating process of discharge reaction at temperature over 5000□.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of the first prior art.

FIG. 2 shows a schematic view of the second prior art.

FIG. 3A shows a perspective view that no silicide is formed on the surface of conventional catalytic hot wire.

FIG. 3B shows a perspective view that silicide is already formed on the surface of conventional catalytic hot wire.

FIG. 4A shows a partially enlarged sectional view that no silicide is formed on the surface of conventional catalytic hot wire.

FIG. 4B shows a partially enlarged sectional view that silicide is already formed on the surface of conventional catalytic hot wire.

FIG. 5 is a view illustrating the present invention.

FIG. 6 shows a flow chart of the present invention.

FIG. 7 shows a schematic view of the processing system of the present invention.

FIG. 8 shows a partially enlarged view of FIG. 7.

FIG. 9A shows a schematic view of the first discharge process of the present invention.

FIG. 9B shows a schematic view of the second discharge process of the present invention.

FIG. 9C shows a schematic view of the third discharge process of the present invention.

FIG. 10 shows a schematic view that the structure of the present invention is applied to HWCVD device.

FIG. 11 shows another schematic view that the structure of the present invention is applied to HWCVD device.

FIG. 12 shows a partially enlarged view that the structure of the present invention is applied to HWCVD device.

FIG. 13 shows an appearance view of common tungsten filament.

FIG. 14 shows an appearance view of the present invention.

FIG. 15 shows a partially enlarged view of the present invention.

FIG. 16 shows an EDS analysis view of the protective layer of the present invention.

FIG. 17 shows a schematic view that common tungsten filament is heated to 600° C.

FIG. 18 shows a schematic view that the present invention is heated to 600° C.

FIGS. 19A, 19B, 19C and 19D show the surface the metal wire structure with high-melting-point protective layer after completion of discharge that is amplified to 25 times, 50 times, 100 times and 200 times respectively.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a metal wire structure with high-melting-point protective layer and its manufacturing method. Referring to FIG. 5, the metal wire structure 100 of the present invention with high-melting-point protective layer comprises:

a core 20, which is made of metal material and is shaped as a thread;

a protective layer 30, which is made of either metal carbide or metal nitride; the protective layer 30 is gradually bonded onto the surface of the core 20 until a preset thickness, and then fully covered onto the core 20 through a plating process of discharge reaction at temperature over 5000° C.; moreover, the cross section of the core 20 is of round (shown in FIG. 5), rectangular, flat or other geometric shapes.

Referring to FIG. 6, the manufacturing method of the present invention includes the following steps:

preparation step 11: preparing a core 20 and a discharge device 40, of which the core 20 in a threaded shape is made of metal material; the discharge device 40 is provided with a positive electrode 41, a negative electrode 42, a discharge reaction tank 43, a discharge processing medium 44, an electrode fixed portion 45 and a discharge reaction member 46; the discharge processing medium 44 is placed into the discharge reaction tank 43, the electrode fixed portion 45 is used to fix the core 20, which is linked to the negative electrode 42; the discharge reaction member 46 made of metal is linked to the positive electrode 41; a preset discharge gap S is defined between the core 20 and the discharge reaction member 46, and filled with the discharge processing medium 44; furthermore, the discharge processing medium 44 consists of either carbon atom or nitrogen atom;

discharge step 12: the discharge device 40 is activated to enable electrical discharge of the core 20 and the discharge reaction member 46; referring to FIGS. 9 A, 9B and 9C, the local temperature in this discharge process is over 5000° C., so metal atoms of the core 20 impinge dispersedly on an exterior surface of the discharge reaction member 46, meanwhile the metal atoms of the discharge reaction member 46 are combined with the atoms of the discharge processing medium 44 (i.e. carbon or nitrogen atoms), and impinge dispersedly on the exterior surface of the core 20, so a protective layer 30 is gradually formed on the exterior surface of the core 20;

finish step 13: a metal wire structure 100 with high-melting-point protective layer is made which comprises:

a core 20, made of metal material and shaped as a thread;

a protective layer 30, made of either metal carbide or metal nitride; the protective layer 30 is gradually bonded onto the surface of the core 20 until a preset thickness of protective layer, and then fully covered onto the core 20 through a plating process of discharge reaction at temperature over 5000° C.

More specifically, the core 20 is made of W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn or tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or manganese alloy. The protective layer 30 is made of either metal carbide or metal nitride containing W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or manganese alloy (e.g.: TiC, TaC, TiN, WC and CrC).

In addition, the core 20 and the protective layer 30 can be made of materials with similar thermal expansion coefficient so as to prevent the bonding relation due to thermal expansion. For example: when the core 20 is made of tungsten, the expansion coefficient is about 4.6 (10⁻⁶/° C.), and the protective layer 30 can be made of WC or TiC, with the thermal expansion coefficient of WC approx. 3.7 to 5.7 (10⁻⁶/° C.), and that of TiC approx. 5.5 (10⁻⁶/° C.), showing a similar thermal expansion coefficient of the core 20 and the protective layer 30.

It is assumed that the discharge reaction member 46 is made of titanium, and the discharge processing medium 44 is a solution containing carbon atom; the key feature of the present invention lies in the discharge mechanism, whereby a temperature over 5000° C. is generated during the discharge process, so that the titanium atom of the discharge reaction member 46 and the carbon atom in the discharge processing medium 44 are combined into TiC impinging on the electrode (tungsten is assumed), and closely bonded onto the electrode to form gradually a thin TiC protective layer. The bonding process among atoms presents excellent compactness. In other words, when the metal wire structure 100 of the present invention with a high-melting-point protective layer (it is assumed that the core 20 is made of tungsten), the operating temperature of the energized tungsten filament is about 1850° C.˜2100° C., much lower than the temperature generated by TiC protective layer. So, the TiC protective layer no longer reacts with the reactant gas (e.g. silicon hydride or hydrogen), nor generates silicide. Certainly, the discharge processing medium 44 is also a kind of gas containing nitrogen atom (e.g.: N₂), so that the carbon and nitrogen atoms are combined into TiN impinging on the electrode, and closely bonded onto the electrode to form gradually a thin TiN protective layer.

In addition, as for the metal wire structure 100 with high-melting-point protective layer after completion of discharge, the surface is shown in FIGS. 19A, 19B, 19C and 19D, wherein the surface is amplified to 25 times, 50 times, 100 times and 200 times.

The present invention can be applied to a HWCVD device (namely, the catalytic hot wire 94 of prior art can be replaced as a metal wire structure 100 of the present invention with a high-melting-point protective layer); referring to FIGS. 10, 11 and 12, when silicon hydride (SiH₄) (shown by the arrow) is filled into the reaction chamber 91, and the temperature of the core 20 hasn't reached the melting point of silicon (about 1410° C.), the protective layer 30 can protect the core 20 not to contact with gas (the melting point of the protective layer 30 is over 5000° C.). Hence, it helps to resolve the shortcomings of prior art that gas cannot be fully decomposed, with some residual gas left on the surface of catalytic hot wire 94 (i.e. generation of silicide).

The products of the present invention can be used in some applications such as:

[a] Example one: the metal wire structure with high-melting-point protective layer is heated up, then the reactant gas passing through the surface of the protective layer 30 is heated to generate free radical, allowing for technical applications for cleaning the surface of Si, Al and TiN, as well as copper film (i.e. Cu film), etc. The reactant as can be selected optionally from any group of hydrogen (H₂), ammonia (NH₃), silicon hydride (SiH₄), hydrazine (NH₂NH₂) and water (H₂O). For instance, if the reactant gas is hydrogen (H₂) or vapor (H₂O), it can generate free radical of H atom, if the reactant gas is ammonia (NH₃), it can generate free radical of NH and NH₂ atoms.

[b] Example two; the metal wire structure with high-melting-point protective layer is heated up, then the reactant gas (CH₄) passing through the surface of the metal wire is heated to generate free radical (C atom, etc), allowing for DLC (Diamond-Like Carbon) plating.

The actual test results of the present invention are described below:

FIGS. 13 and 14 depict separately the perspective view of conventional tungsten filament and the present invention. FIG. 15 depicts a partially enlarged view of the present invention, wherein 2˜3 μm protective layer 30 of the present invention can be clearly observed.

FIG. 16 depicts EDS (Energy Dispersive Spectrometer) analysis of the protective layer 30, of which carbon atom is 67%, titanium atom 3% and tungsten atom 30%, proving the covering effect of the protective layer 30.

Vickers hardness test results indicate that, the hardness of common tungsten filament is HV400, but that of the present invention increases to HV700; common tungsten filament will be softened when it is heated electrically (DC) up to 600° C. (shown in FIG. 17), but the present invention lacks of such phenomenon when it is heated up to 600° C. (shown in FIG. 18).

In addition, the temperature distribution of common tungsten filament is shown in Table 1 and FIG. 17 (serial number of positions in Table 1 corresponds to that of positions A1˜A14 in FIG. 17). It can be seen that, the temperature distribution of common tungsten filament is extremely uneven (high temperature concentrated at right side). However, the temperature distribution of the present invention is shown in Table 2 and FIG. 18 (serial number of positions in Table 2 corresponds to that of positions B1˜B14). It can be seen that, the temperature distribution of the present invention is even.

TABLE 1
Temperature distribution of common tungsten filament
Serial No of positions Temperature(° C.)
Point A1               596
Point A2               580
Point A3               552
Point A4               511
Point A5               492
Point A6               490
Point A7               507
Point A8               518
Point A9               328
Point A10              338
Point A11              57
Point A12              68
Point A13              44
Point A14              42

TABLE 2
Temperature distribution of the present invention
Serial No of positions Temperature(° C.)
Point B1               606
Point B2               600
Point B3               603
Point B4               596
Point B5               598
Point B6               600
Point B7               598
Point B8               577
Point B9               104
Point B10              68
Point B11              49
Point B12              33
Point B13              35
Point B14              29

It is proved experimentally that, in an oxygen-bearing environment, if the catalytic hot wire 94 of prior art is made of tungsten, and the temperature is about 1000° C.˜2000° C., wire rupture may occur; but, due to the protective layer 30, the core 20 of the present invention will not rupture in an oxygen-bearing environment at 1000° C.˜2000° C.

The advantages and efficacies of the present invention can be summarized below:

1. Without generation of silicide. In the prior art, when silicon hydride (SiH₄) contacts with hot wire device 840 or catalytic hot wire 94 whose temperature hasn't reached the melting point of silicon (about 1410° C.), the gas cannot be fully decomposed, with some residual gas left on the surface of hot wire device 840 or catalytic hot wire 94. Namely, silicide 941 is formed. When the silicide 941 is fully covered onto the catalytic hot wire 94, the function of the catalytic hot wire 94 will be lost, affecting the process of hot wire chemical vapor deposition seriously. With the use of discharge processing method, a protective layer 30 is formed on the exterior surface of the core 20, thus maintaining the function of the core 20 and preventing reaction of gas with the core 20 against generation of silicide 941.

2. Producing protective effects. In the prior art, the silicide 941 is prone to form many cracks 942 due to expansion and contraction, affecting the function and service life of the catalytic hot wire 94; with the use of protective layer 30, the present invention can prevent the forming of silicide 941 on the core 20 for realizing the protective effects.

The aforementioned description of the preferred embodiments shows that the present invention can really meet the above-specified purpose and patent specifications, so the patent application is claimed herein.

Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.

Claims

1. A manufacturing method of metal wire structure with high-melting-point protective layer comprising the following steps: preparation step: preparing a core and a discharge device, of which the core in a threaded shape is made of metal material; said discharge device being provided with a positive electrode, a negative electrode, a discharge reaction tank, a discharge processing medium, an electrode fixed portion and a discharge reaction member; said discharge processing medium being placed into said discharge reaction tank, said electrode fixed portion being used to fix said core, which is linked to said negative electrode; said discharge reaction member made of metal being linked to said positive electrode; a preset discharge gap being defined between said core and said discharge reaction member, and filled with said discharge processing medium; said discharge processing medium consisting of either carbon atom or nitrogen atom;discharge step: said discharge device being activated to enable electrical discharge of said core and said discharge reaction member; a local temperature in this discharge process being over 5000□, so metal atoms of said core impinging dispersedly on an exterior surface of said discharge reaction member, meanwhile the metal atoms of said discharge reaction member being combined with atoms in said discharge processing medium, and impinging dispersedly on said exterior surface of said core, so a protective layer being gradually formed on said exterior surface of said core;finish step: a metal wire structure with high-melting-point protective layer being made which comprises: a core which is made of metal material and is shaped as a thread;a protective layer which is made of either metal carbide or metal nitride;said protective layer being gradually bonded onto an exterior surface of said core until a preset thickness, and then fully covered onto said core through a plating process of discharge reaction at temperature over 5000□.

2. The method defined in claim 1, wherein said discharge reaction member is made of W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or manganese alloy.

3. A metal wire structure with high-melting-point protective layer comprising: a core which is made of metal material and is shaped as a thread;a protective layer which is made of either metal carbide or metal nitride; said protective layer being gradually bonded onto an exterior surface of said core until a preset thickness, and then fully covered onto said core through a plating process of discharge reaction at temperature over 5000□.

4. The structure defined in claim 3, wherein said core is made of W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or manganese alloy.

5. The structure defined in claim 3, wherein said protective layer is made of metal carbide containing W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or manganese alloy.

6. The structure defined in claim 3, wherein said protective layer is made of metal nitride containing W, Pt, Pd, Mo, Ti, Nb, Ta, Co, Ni, Cr, Mn, tungsten alloy, platinum alloy, palladium alloy, molybdenum alloy, titanium alloy, niobium alloy, tantalum alloy, cobalt alloy, nickel alloy, chrome alloy, or manganese alloy.