JP4224660B2 - Copper wiring board and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device substrate and a method for manufacturing the same, and particularly to a copper wiring substrate using low resistance copper as an electrode material or a wiring material.
[0002]
[Prior art]
In recent years, liquid crystal display devices are frequently used for display devices of personal computers. A liquid crystal display device is configured by enclosing liquid crystal between a pair of substrates and mounting auxiliary elements such as a liquid crystal driving circuit, a backlight, and a color filter on the substrate. In the liquid crystal display device, an active matrix system is used that can display an arbitrary character or figure with high accuracy using a large number of pixels. As an example of an active matrix type liquid crystal driving circuit, a thin film transistor (TFT) type is known.
FIG. 12 and FIG. 13 are diagrams showing one structural example of a general bottom gate type thin film transistor substrate 40. 12 is a plan view, and FIG. 13 is a cross-sectional view taken along line AA in FIG. As shown in the figure, gate wirings 3 and source wirings 4 are wired in a matrix on a transparent and insulating substrate 1. A region surrounded by the gate wiring 3 and the source wiring 4 is a pixel 81. Each pixel 81 is provided with a thin film transistor 80.
[0003]
The thin film transistor 80 is provided with a gate insulating film 89 on a gate wiring 3 made of a conductive material such as Al, Cr, Ta, or an alloy thereof, and on a gate electrode 5 provided by being drawn out from the gate wiring 3. A semiconductor active film 90 made of amorphous silicon (a-Si) is provided so as to face the gate electrode 5, and an upper side of both sides of the semiconductor active film 90 is doped with an impurity serving as a donor such as phosphorus at a high concentration. Ohmic contact films 93a and 93b made of silicon or the like are placed. Further, the source electrode 6 and the drain electrode 7 made of a conductive material such as Al, Cr, Ta, or an alloy thereof are formed on the gate insulating film 89 so as to partially overlap the ohmic contact films 93a and 93b. It is provided to oppose. A contact hole 99 is provided at one end of the drain electrode 7 and is connected to the transparent pixel electrode 8 made of indium tin oxide (ITO) or the like.
[0004]
A passivation film 96 is provided on the gate insulating film 89, the source electrode 6, the drain electrode 7, the pixel electrode 8, and the like. An alignment film (not shown) is formed on the passivation film 96, and liquid crystal is sealed in contact with the alignment film to constitute an active matrix liquid crystal device. The orientation of the liquid crystal molecules is controlled by applying an electric field to the liquid crystal molecules through the pixel electrode 8.
[0005]
As a method of manufacturing the thin film transistor substrate shown in FIGS. 12 and 13, a thin film forming means such as a sputtering method using a target made of a conductive metal such as aluminum, chromium, or tantalum and applying a DC voltage to the target is used. The conductive metal thin film made of aluminum, chromium, tantalum or the like is formed on the transparent insulating substrate 1 such as glass. Next, after removing the conductive metal thin film at a place other than the formation of the gate electrode on the substrate 1 by the photolithography method to form the gate electrode 5, SiO 2 is formed using a thin film forming means such as a CVD method. ₂ A gate insulating film 89 made of SiNx and a semiconductor active film 90 are formed. Next, ohmic contact films 93a and 93b are formed on these by the above-described sputtering method and photolithography method, and then the ohmic contact film is formed by masking the formed source electrode 6 and drain electrode 7. After removing a part of the film and dividing the ohmic contact film, a passivation film 96 is formed by a CVD method or the like to obtain the thin film transistor substrate 40.
[0006]
[Problems to be solved by the invention]
By the way, in recent years, a high-speed operation of a liquid crystal display device has been demanded, and a signal transmission delay in a conductive material such as a gate wiring, a source wiring, a gate electrode, a source electrode, and a drain electrode has become a problem. I came. As means for solving this problem, it has been proposed to use copper (Cu), which is an inexpensive metal having a lower resistance than conductive metals such as aluminum, chromium, and tantalum that have been conventionally used as wiring materials. .
When copper is used as the conductor of the thin film transistor substrate having the structure shown in FIGS. 12 and 13, the adhesive force at the interface between the substrate and copper as the conductor or between the silicon oxide insulating film and copper as the conductor is reduced. The phenomenon that the conductor peels off during the process of manufacturing the thin film transistor substrate is weak.
[0007]
As a measure to prevent the peeling of the conductor by increasing the adhesion force of the bonding surface between the substrate and copper or the bonding surface between the insulating film and copper, means to improve the adhesion by annealing after forming the copper thin film As shown in FIG. 14, for example, between a gate insulating film made of silicon oxide or a glass substrate 1 and a copper wiring 2 serving as a conductor, both a substrate such as chrome and aluminum, an insulating film, and copper. A barrier metal layer 9 made of a metal having good adhesion is formed, and a means is adopted in which the barrier metal layer 9 and the copper wiring 2 have a two-layer structure.
[0008]
However, the method of annealing after forming a copper thin film cannot provide satisfactory bonding strength. In addition, in the method of forming a two-layer structure of a barrier metal layer made of metal with good adhesion and copper, the number of film forming steps increases, resulting in a decrease in production efficiency. In the subsequent etching step, resist selection and etchant selection are performed. Such a complicated work is required. If the selection of the resist and the selection of the etchant are wrong, copper is preferentially etched over chromium and aluminum, and phenomena such as thinning of the wire and disappearance of the copper film occur as shown by 2b in FIG.
An object of the present invention is to provide a copper wiring substrate having a copper thin film having excellent adhesion on an insulating substrate or an insulating film. Furthermore, it aims at providing the method which can form such a copper thin film excellent in adhesiveness reliably by a simple method.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a copper wiring base in which a copper thin film is deposited on a glass substrate, a quartz substrate or a silicon oxide thin film surface via a silicon nitride altered layer. Silicon nitride altered layer is SiO ₂ Bonds and SiNx bonds are mixed, and SiO ₂ A portion containing 10% or more of SiNx bonds exists in the bonds. By providing such a silicon nitride altered layer, the copper thin film can be firmly attached to the surface of the glass substrate, quartz substrate or silicon oxide film.
In addition, the method for producing a copper wiring board according to the present invention comprises irradiating the surface of a glass substrate, a quartz substrate or a silicon oxide film with nitrogen plasma before or at the same time as the formation of the copper thin film. SiO on substrate or silicon oxide film surface ₂ A means for forming and modifying SiNx bonds during bonding was employed.
As means for irradiating nitrogen plasma, there are a method using a cleaning chamber attached to a plasma film forming facility and a method using a plasma film forming chamber of a plasma film forming facility. In addition, as a method of irradiating with nitrogen plasma, prior to the copper thin film formation, the surface of the glass substrate, quartz substrate or silicon oxide film is irradiated with nitrogen plasma to form a silicon nitride altered layer, and then the copper thin film is formed. A copper thin film at the same time while irradiating the surface of the glass substrate, quartz substrate or silicon oxide film with nitrogen plasma, forming a silicon altered layer and a part of the copper thin film, and then forming the remainder of the copper thin film There is a way to do it.
By irradiating the glass substrate, quartz substrate, or silicon oxide film surface with nitrogen plasma, nitrogen atoms penetrate from the surface to a depth of about 100 angstroms to form SiNx bonds. According to the method of the present invention, it can be easily carried out within a series of copper thin film forming steps without increasing the number of special steps.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
First, the object of the present invention is a glass substrate, a quartz substrate, a silicon oxide film or the like such as SiO. ₂ Is the main component. Specifically, a transparent insulating glass substrate used in a liquid crystal display device, a silicon oxide-based insulating film used in a liquid crystal driving circuit, and the like can be given. These SiO ₂ For example, when a circuit board is manufactured using a copper thin film, the base material containing the main component of copper has a problem of peeling or thinning of the copper thin film.
[0011]
The altered silicon nitride layer of the present invention is SiO ₂ Bonds and SiNx bonds are mixed. SiO ₂ Nitrogen atoms enter from the surface of the porous substrate, and SiO ₂ A SiNx bond such as SiNx or SiON is formed during bonding. The ratio of SiNx bonds gradually decreases from the surface of the base material such as a glass substrate, quartz substrate or silicon oxide film to the inside, and eventually becomes the base material itself. The boundary between the silicon nitride altered layer and the base material is not clear.
FIG. 1 is a diagram showing an example of a cross-sectional structure of a copper wiring board according to the present invention.
In FIG. 1, 1 is a transparent and insulating substrate such as glass. The substrate 1 may be a quartz substrate or a silicon oxide film instead of the glass substrate. The copper wiring 2 on the surface of the substrate 1 is formed by sputtering. The copper wiring 2 constitutes, for example, a gate line, a source / drain line, a gate electrode, a source / drain electrode, etc. in a thin film transistor. In the copper wiring substrate of the present invention, the surface portion of the substrate 1 that contacts the copper wiring 2 is the silicon nitride altered layer 1a. Only the surface portion of the substrate 1 is a silicon nitride altered layer 1a containing nitrogen atoms, and the majority is the substrate itself.
[0012]
In order to obtain a copper wiring substrate having the above-described silicon nitride altered layer, the substrate surface is obtained by irradiating nitrogen plasma. For example, a glass substrate is set in a cleaning chamber of a plasma processing apparatus, a high frequency current of 13.56 MHz is applied to the substrate side in a nitrogen atmosphere to form nitrogen plasma, and the surface of the substrate subjected to reverse sputtering cleaning is subjected to ESCA (Electron spectroscopy for ESC). The results observed in chemical analysis) are shown in FIG. As is apparent from FIG. 2, a carbon and nitrogen profile that appears to be an organic substance attached to the surface is recognized from the surface to about 7 angstroms. At a depth of about 14 angstroms from the surface, the oxygen concentration is found to be about 60% and the nitrogen concentration is about 10%. Other elements include oxygen and silicon. From the above results, SiO at this depth ₂ It can be estimated that the bonding ratio is about 86% (60 / (60 + 10) = 0.857) and the SiNx bonding ratio is about 14% (10 / (60 + 10) = 0.143). The nitrogen concentration gradually decreases as the depth increases, but a nitrogen concentration of several percent is still observed at a depth of 112 angstroms. By providing such a silicon nitride altered layer, the adhesion between the glass substrate and the copper thin film is significantly improved. In order to improve the adhesion, it is sufficient that the portion where the ratio of SiNx bonds is 6% or more is 50 angstroms or more. More preferably, the portion where the SiNx bond ratio is 10% or more should be 50 angstroms or more.
[0013]
A copper thin film having a thickness of about 2000 angstroms was formed by direct current sputtering on the surface of the glass substrate subjected to the nitrogen plasma treatment as described above. FIG. 3 shows the result of observing the vicinity of the interface between the glass substrate and the copper thin film by ESCA. From FIG. 3, only the copper profile is obtained from the substrate surface to about 1975 Å, but the copper profile descends at about 1975 Å, and oxygen and silicon, which are constituent elements of the substrate, increase. At the same time, the nitrogen atoms increase and are found to exist up to a depth of about 2225 angstroms.
The copper thin film of this substrate has a strong adhesive strength. For example, an adhesive tape is applied to the surface of the copper thin film, and the copper thin film does not peel off even if it is pulled strongly.
[0014]
On the other hand, the result of having observed the surface state of the glass substrate which does not perform a nitrogen plasma process by ESCA is shown in FIG.4 and FIG.5. FIG. 4 shows the results of ESCA observation of the surface of a glass substrate that is not subjected to any treatment. As shown in FIG. 4, the profiles of oxygen and silicon continue throughout the region except that a carbon profile that appears to be adhering carbon is observed on the pole surface. FIG. 5 shows the result of observing the vicinity of the interface between the substrate and the copper thin film by ESCA after forming a copper thin film having a thickness of about 2000 angstroms on the surface of the glass substrate by sputtering. As shown in FIG. 5, at the depth of about 1975 angstroms, copper decreases and oxygen and silicon increase.
The adhesive strength of the copper thin film on this substrate is weak, and when the adhesive tape is applied and pulled, it is easily peeled off from the substrate.
[0015]
Next, FIG. 6 shows an example of the substrate surface when cleaning by reverse sputtering is performed in an argon atmosphere prior to forming a copper thin film. FIG. 6 is an ESCA observation result of the glass substrate surface that has been subjected to a cleaning process by argon reverse sputtering. Similar to FIG. 4, the profile of oxygen and silicon continues throughout the entire region except that a carbon profile that appears to be adhering carbon is observed on the extreme surface. FIG. 7 shows the result of observing the vicinity of the interface between the substrate and the copper thin film by ESCA by forming a copper thin film having a thickness of about 2000 angstroms on the surface of the glass substrate by sputtering. Similar to FIG. 4, copper decreases and oxygen and silicon increase at a depth of about 2000 angstroms.
The adhesive strength of the copper thin film on the substrate is also weak, and when the adhesive tape is applied and pulled, it is easily peeled off from the substrate.
[0016]
Hereinafter, a method for producing a copper wiring board of the present invention will be described based on embodiments.
(First embodiment)
In the case where a cleaning chamber is attached to the plasma film forming facility, nitrogen plasma treatment can be performed using the cleaning chamber. When reverse sputtering cleaning is performed, if nitrogen gas is introduced into the cleaning chamber instead of argon gas to form nitrogen plasma, nitrogen atoms enter from the surface simultaneously with the cleaning process, and the base material changes in quality. .
FIG. 8 is a diagram illustrating a schematic configuration of a plasma film forming facility provided with a cleaning chamber. In FIG. 8, a loading chamber 10, a cleaning chamber 11, and a sputter deposition chamber 12 are connected via gate valves 13 and 14. Each of these chambers is configured such that the indoor atmosphere and pressure can be arbitrarily adjusted by an exhaust unit and a gas supply mechanism (not shown).
The loading chamber 10 is a facility for mounting the substrate 1 to be processed in the cleaning chamber 11 in the cleaning chamber 11. A link-type transport mechanism (not shown) is provided in the loading chamber 10, and the substrate 1 to be processed is transported into the cleaning chamber 11 by opening the gate valve 13 as necessary, and the substrate electrode 15 in the cleaning chamber 11 is transported. It is configured so that it can be attached to. Usually, in the cleaning chamber 11, a direct current or a high frequency current is applied to the substrate electrode 15 in an argon atmosphere, and the surface of the substrate 1 is sputtered to remove deposits and perform cleaning. The substrate 1 that has been cleaned is sent to the sputter deposition chamber 12 through the gate valve 14.
A substrate electrode 17 and a target electrode 18 are arranged opposite to each other in the sputter deposition chamber 12, and the substrate 1 on which a metal thin film is to be formed is mounted on the substrate electrode 17, and aluminum, chromium, tantalum, copper are attached to the target electrode 18. A metal target 19 to be deposited is mounted. Usually, in the sputter deposition chamber 12, a direct current is applied to the target electrode 18 in an argon atmosphere, the target 19 is sputtered, and target molecules are deposited on the substrate.
[0017]
In the film forming apparatus provided with the cleaning chamber as described above, the reverse sputtering cleaning process performed in the cleaning chamber is performed in a nitrogen atmosphere instead of the argon atmosphere, whereby the cleaning process and the nitrogen plasma irradiation process are performed at the same time. In addition, the altered silicon nitride layer of the present invention can be formed. In order to obtain a nitrogen atmosphere, nitrogen gas alone or a mixed gas of nitrogen and argon may be used.
The substrate 1 that has been irradiated with the nitrogen plasma is sent to the sputter deposition chamber 12 and subjected to a sputter deposition process of a copper thin film.
[0018]
An example of the manufacturing method of the copper wiring board in this embodiment is shown below.
First, the glass substrate 1 is set on the substrate electrode 15 in the cleaning chamber 11. Nitrogen gas is introduced into the cleaning chamber 11 and a high frequency current of 13.56 MHz is applied to the substrate electrode 15 to perform nitrogen plasma irradiation treatment. Next, the substrate 1 is transferred to the sputter deposition chamber 12 in a vacuum and set on the substrate electrode 17. Next, argon gas is introduced into the sputter deposition chamber 12, a copper target is set on the target electrode 18, a direct current is applied to the target electrode 18, and a copper thin film having a thickness of about 2000 angstroms is formed by direct current sputtering. .
[0019]
When the surface of the copper wiring board thus formed was observed by ESCA, only a copper profile was observed from the surface to about 2000 angstroms. As it becomes deeper than 1900 angstroms, the copper profile rapidly decreases and the oxygen and silicon profiles increase. At the same time, a nitrogen profile also appears and gradually decreases with increasing depth. The nitrogen concentration at a position 2000 angstroms deep from the surface is found to be about 8% and the oxygen concentration is about 50%, and the SiNx bond ratio at this position is about 14%. Further, even at a position 2100 angstroms deep from the surface, the nitrogen concentration is recognized to be about 6% and the oxygen concentration is about 60%, and the ratio of SiNx bonds at this position is still about 9%.
[0020]
When a test was carried out in which an adhesive tape was applied to the surface of the copper wiring and the adhesive tape was strongly peeled off from the substrate, no copper foil film was peeled off in 10 samples.
On the other hand, all the copper foil films in 10 samples were isolated from the conventional copper thin film formed on the substrate not subjected to any treatment. Moreover, as for the copper thin film formed on the board | substrate which performed the irradiation process of argon plasma, the copper foil film | membrane of 3 samples out of 10 samples isolated.
[0021]
(Second Embodiment)
In the case where the film forming apparatus is not provided with a cleaning chamber, nitrogen film irradiation treatment can be performed using the film forming chamber.
FIG. 9 is a schematic view illustrating an example of a sputter film forming chamber used in the method of the present invention. As shown in FIG. 9, the sputter deposition chamber 22 is provided with a target electrode 18 as a first electrode on the upper portion thereof, and the target 19 is provided on the lower surface of the target electrode 18 using a normal means such as an electrostatic chuck. And is detachable. A substrate electrode 17 is provided as a second electrode in the lower part of the sputter deposition chamber 22, and a glass or quartz substrate 1 is detachably mounted on the upper surface of the substrate electrode 17.
As a material for the target 19, in the case of forming a gate electrode, a source electrode, and a drain electrode of a thin film transistor, copper is used in the present invention in addition to a metal selected from aluminum, chromium, tantalum, titanium, molybdenum and the like. In addition, a-Si: n of the thin film transistor ⁺ Is used, phosphorus-doped silicon is used. As the substrate 1, a glass substrate or a quartz substrate can be suitably used. Alternatively, a silicon oxide thin film may be formed on the surface.
[0022]
The sputter film forming chamber 22 of the present embodiment is different from the sputter film forming chamber 12 described above in that a current can be applied to both the substrate electrode 17 and the target electrode 18. The current, voltage, power, frequency, etc. applied to both electrodes can be adjusted independently according to the purpose of processing.
That is, a first high-frequency power source 25 is connected to the first target electrode 18, and a matching circuit 25 a is incorporated between the target electrode 18 and the first high-frequency power source 25, and a reflected wave of the high-frequency circuit. Has the effect of counteracting. A DC power supply 28 is connected to the first target electrode 18 through a low-pass filter 27 for impedance adjustment. The low-pass filter 27 adjusts the circuit impedance to infinity so that a high-frequency current is not applied to the DC power supply 28.
On the other hand, a second high-frequency power source 35 is connected to the second substrate electrode 17, and a matching circuit 35a that has the same effect as the matching circuit 25a is also provided between the substrate electrode 17 and the second high-frequency power source 35. Is incorporated.
The sputter film forming chamber 22 is provided with an evacuation facility 60a for evacuation or gas exhaust, a gas supply facility 60b to the sputter film formation chamber 22, and the like are simplified in FIG. Indicated.
[0023]
Using the sputter deposition chamber 22 configured as described above, if a current is applied to the substrate electrode side in a nitrogen atmosphere, a nitrogen plasma irradiation treatment can be performed, and a current is applied to the target electrode side in an argon atmosphere. Then, a sputter film forming process can be performed.
[0024]
An example of the manufacturing method of the copper wiring board in this embodiment is shown below.
First, the glass substrate 1 is set on the substrate electrode 17 in the sputter deposition chamber 22. Nitrogen gas is introduced into the sputter deposition chamber 22, and a high frequency current of, for example, 13.56 MHz is applied to the substrate electrode 17 to perform a nitrogen plasma irradiation process. Next, after introducing argon gas into the sputter deposition chamber 22 and switching from the nitrogen atmosphere to the argon atmosphere, a copper target is set on the target electrode 18, a direct current is applied to the target electrode 18, and the thickness is increased by direct current sputtering. A copper thin film of about 2000 Å is formed.
[0025]
As in the case of the first embodiment, the surface of the copper wiring board thus formed is recognized to have a nitrogen concentration of about 7% and an oxygen concentration of about 60% even at a depth of 2100 angstroms from the surface. The proportion of SiNx bonds at this position is still about 10%. Further, in the same peel test as in the first embodiment, no peeling of the copper thin film is observed in 10 samples.
[0026]
(Third embodiment)
In the above two embodiments, the copper thin film was formed after the nitrogen plasma irradiation treatment. However, the nitrogen plasma irradiation treatment and the copper thin film were changed by selecting the method of switching the atmospheric gas and applying the current. It is possible to perform a part of sputter film formation at the same time. According to this method, it is possible to form a gate electrode and a source / drain electrode using a copper electrode when forming a thin film transistor.
[0027]
First, the glass substrate 1 is set on the substrate electrode 17 in the sputter deposition chamber 22. Nitrogen gas is introduced into the sputter deposition chamber 22 and a high frequency current having a frequency higher than usual of 40 MHz or higher is applied to the target electrode 18. As the frequency of the high-frequency current applied to the target electrode 18 increases, the target's self-bias potential becomes shallower, the chance of heavy ions in the atmosphere striking the target decreases, sputtering of the target decreases, and the plasma state is maintained. The substrate surface is irradiated. As a result, a silicon nitride altered layer is formed on the surface of the glass substrate 1, and a copper thin film is also deposited to a small extent. The self-bias potential of the target becomes shallow, and the nitrogen plasma irradiation effect appears when the frequency becomes a high frequency of approximately 40 MHz or more. Therefore, for example, a high frequency current of about 40 MHz may be applied.
[0028]
After performing nitrogen plasma irradiation treatment in this way, argon gas is introduced into the sputter deposition chamber 22 and switched to an argon atmosphere, and then a copper target is set on the target electrode 18 according to a normal method. A direct current is applied to the film, and a copper thin film having a thickness of about 2000 angstroms is formed by sputtering by direct current sputtering. The copper thin film formed in this way is integrated and solid with the copper thin film generated in the nitrogen plasma irradiation process.
[0029]
An example of the manufacturing method of the copper wiring board in this embodiment is shown below.
First, the glass substrate 1 is set on the substrate electrode 17 in the sputter deposition chamber 22. Nitrogen gas is introduced into the sputter deposition chamber 22 and a high frequency current of 40 MHz, for example, is applied to the target electrode 18 to perform nitrogen plasma irradiation treatment. Next, after introducing argon gas into the sputter deposition chamber 22 and switching from the nitrogen atmosphere to the argon atmosphere, a copper target is set on the target electrode 18, a direct current is applied to the target electrode 18, and the thickness is increased by direct current sputtering. A copper thin film of about 2000 Å is formed.
[0030]
As in the case of the first embodiment, the surface of the copper wiring board thus formed is recognized to have a nitrogen concentration of about 5% and an oxygen concentration of about 55% even at a depth of 2000 angstroms from the surface. The proportion of SiNx bonds at this position is still about 8%. Further, in the same peel test as in the first embodiment, no peeling of the copper thin film is observed in 10 samples.
[0031]
(Fourth embodiment)
In the third embodiment, the high-frequency power source 25 connected to the target electrode 18 needs to have a high frequency. However, the same nitrogen plasma irradiation effect can be obtained by applying a current to both the target electrode 18 and the substrate electrode 17 without using a power source having a higher frequency.
That is, when the current applied to the target electrode 18 is a direct current, the copper target is sputtered while suppressing the load of the applied current, and a high frequency current is also applied to the substrate electrode 17 so that the surface of the substrate 1 is nitrogen plasma. Irradiate. In this case, the direct current applied to the target electrode 18 is a weak current. When the current applied to the target electrode 18 is a high-frequency current, the copper target is sputtered with the frequency lowered so that the bias potential of the target does not become shallow, and at the same time, the high-frequency electrode is applied to the substrate electrode 17. Plasma irradiation treatment is performed on the surface of the substrate 1. For example, about 13.56 MHz is applied to the target electrode 18, and about 13.56 MHz and 200 W are applied to the substrate electrode 17. In this method, reverse sputtering cleaning and sputtering film formation are performed simultaneously, but a silicon nitride-altered layer on the surface of the substrate 1 can be reliably formed.
[0032]
An example of the manufacturing method of the copper wiring board in this embodiment is shown below.
First, the glass substrate 1 is set on the substrate electrode 17 in the sputter deposition chamber 22, and nitrogen gas is introduced into the sputter deposition chamber 22.
A copper target is set on the target electrode 18 and a thin direct current of about 100 W or a high frequency current of a low frequency of about 13.56 MHz is applied to the target electrode 18 to form a copper thin film by sputtering. At the same time, a high frequency current of about 13.56 MHz is also applied to the substrate electrode 17.
In this way, by applying current to both the target electrode 18 and the substrate electrode 17, it is possible to irradiate nitrogen plasma without substantially forming a copper thin film.
Next, an argon gas is introduced into the sputter deposition chamber 22, and a direct current is applied to the target electrode 18 without applying a load to the substrate electrode 17, and the remaining copper thin film having a thickness of about 2000 Å is formed by a normal method. Is sputtered.
[0033]
As in the case of the first embodiment, the surface of the copper wiring board thus formed is recognized to have a nitrogen concentration of about 9% and an oxygen concentration of about 60% even at a depth of 2150 angstroms from the surface. The proportion of SiNx bonds at this position is still about 13%. Further, in the same peel test as in the first embodiment, no peeling of the copper thin film is observed in 10 samples.
[0034]
Further, an example in which a thin film transistor is formed on the surface of the copper wiring board formed as described above will be described.
(4-1) Glass substrate on which a copper thin film is formed
FIG. 10A shows a thin film transistor substrate in which a copper thin film 20 is formed on a transparent glass substrate 1 obtained according to the present embodiment. The surface of the transparent glass substrate 1 having a thickness of 1100 microns is a silicon nitride altered layer 1a, and a copper thin film 20 having a thickness of 2000 angstroms is formed through the silicon nitride altered layer 1a.
[0035]
(4-2) Gate electrode patterning
A resist is applied to the surface of the copper thin film 20, pattern exposure is performed in a predetermined gate electrode shape, and unnecessary portions of the copper thin film 20 are removed by etching, followed by patterning for stripping the resist, as shown in FIG. A copper wiring pattern for the gate electrode 5 having a desired line width as shown is obtained.
[0036]
(4-3) Formation of gate insulating film
The inside of the sputtering film forming chamber 22 of the plasma film forming apparatus shown in FIG. _Four + O ₂ A mixed gas atmosphere is set, a dummy electrode is mounted on the target electrode 18, a high frequency current of 200 MHz is applied from the high frequency power supply 25 to the target electrode 18, a load potential is floated to generate plasma, and silicon dioxide is formed on the substrate 1. A gate insulating film 89 is formed as shown in FIG. In the case of this CVD film formation, the frequency of the applied current is set high so that the dummy target mounted on the target electrode 18 is not sputtered, the ion energy applied to the target electrode 18 is reduced, and the high-frequency current is applied to the substrate electrode 17. Is applied to control the ion energy applied to the substrate 1.
[0037]
(4-4) Nitrogen plasma irradiation treatment of gate insulating film
A sputter deposition chamber 22 is filled with a nitrogen atmosphere, a high frequency current of 13.56 MHz is applied to the substrate electrode 17 from a high frequency power supply 35, and the surface of the substrate 1 is irradiated with nitrogen plasma to form a gate as shown in FIG. A silicon nitride altered layer 89 a is formed on the surface of the insulating film 89.
[0038]
(4-5) Formation of semiconductor active film
The inside of the sputter deposition chamber 22 is SiH _Four + H ₂ A high-frequency current of 200 MHz is applied from the high-frequency power source 25 to the target electrode 18 while a dummy electrode is mounted on the target electrode 18 with a mixed gas atmosphere, and a high-frequency current is further applied from the high-frequency power source 35 to the substrate electrode 17. As shown in FIG. 10E, the semiconductor active film 90 made of an a-Si layer is formed on the gate insulating film 89 while controlling the ion energy applied to the gate insulating film 89.
[0039]
(4-6) Formation of ohmic contact film
Argon gas atmosphere is set in the sputter deposition chamber 22 and the target electrode 18 is a-Si: n ⁺ A silicon target made of phosphorus-doped silicon for generation is mounted, a high-frequency current of about 13.56 MHz is applied from the high-frequency power source 25, and further, the load potential applied from the DC power source 28 is -200V, and sputtering is performed. E) a-Si: n on the semiconductor active film 90 as shown in FIG. ⁺ An ohmic contact film 91 made of is formed.
[0040]
(4-7) Patterning of semiconductor active film and ohmic contact film
After applying a resist to the surface of the ohmic contact film 91, pattern exposure is performed in a predetermined shape, unnecessary portions of the semiconductor active film 90 and the ohmic contact film 91 are removed by etching, and patterning is performed to remove the resist. As shown in (A), an island-like semiconductor active film 92 and an ohmic contact film 93 smaller than the gate electrode 5 are obtained. The semiconductor active film 92 and the ohmic contact film 93 are in a position facing the gate electrode 5 with the gate insulating film 89 interposed therebetween.
[0041]
(4-8) Film formation of copper thin film for source electrode and drain electrode
In the same manner as the formation of the copper thin film for the gate electrode, argon gas is introduced into the sputter deposition chamber 22 and a direct current is applied to the target electrode 18 without applying a load to the substrate electrode 17. As shown in FIG. 11B, a copper thin film 94 having a thickness of about 2000 angstroms is formed on the entire surface of the substrate 1 by sputtering.
[0042]
(4-9) Patterning of source electrode and drain electrode
The copper thin film 94 above the central portion of the ohmic contact film 93 and the central portion of the ohmic contact film 93 are removed by etching, and the ohmic contact film 93a is formed on both ends of the semiconductor active film 92 as shown in FIG. , 93b, the source electrode 6 and the drain electrode 7 are obtained separately from each other.
A passivation film made of silicon nitride is formed so as to cover the semiconductor active film 92, the source electrode 6, and the drain electrode 7, thereby completing the thin film transistor 80.
[0043]
Adhesive tape is applied to the surfaces of the source electrode 6 and drain electrode 7 made of copper thin film formed on the gate insulating film 89 made of silicon dioxide subjected to nitrogen plasma irradiation treatment in this way, and the adhesive tape is strongly peeled off from the substrate. As a result of the test, none of the 10 samples separated from the copper foil film was recognized.
On the other hand, all the electrodes in 10 samples were peeled off from the source electrode or the drain electrode formed on the surface of the gate insulating film made of silicon dioxide that was not subjected to any conventional treatment. In addition, 5 out of 10 samples were peeled off from the source electrode or drain electrode formed on the surface of the gate insulating film that had been cleaned with argon plasma.
Thus, after performing nitrogen plasma irradiation treatment on the glass substrate or silicon dioxide thin film surface, the copper thin film obtained by sputtering film formation has a strong bonding strength and can be peeled off in the subsequent thin film transistor manufacturing process. There is no.
[0044]
【The invention's effect】
As described above, the copper wiring substrate of the present invention does not peel off because the bonding strength between the copper wiring and the substrate or between the copper wiring and the silicon oxide film is strong. In addition, according to the method for manufacturing a copper wiring substrate of the present invention, the altered silicon nitride layer can be formed more easily by changing the atmosphere in the sputter film forming step. Furthermore, there are few restrictions on the shape of the apparatus, and the present invention can be implemented not only in a film forming apparatus provided with a normal reverse sputter cleaning chamber but also in a film forming apparatus not provided with a cleaning chamber. In addition, various methods can be selected as a method of applying current to the electrodes, and the application range in the film forming process is extremely wide. Although the bottom-gate thin film transistor has been described in the above embodiment, the scope of application of the present invention is not limited to this. For example, a liquid crystal display device such as a gate wiring or a source / drain wiring of a liquid crystal substrate, and further a silicon oxide Since copper having low specific resistance and low cost can be used for a metal wiring formed on the surface of a high-quality substrate or a silicon oxide thin film, the application range has the effect of expanding without limit.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a cross-sectional structure of a copper wiring board according to the present invention.
FIG. 2 is a diagram showing an ESCA observation result of the surface of a glass substrate subjected to the nitrogen plasma irradiation treatment of the present invention.
FIG. 3 is a diagram showing an ESCA observation result of the surface of a copper wiring board according to the present invention.
FIG. 4 is a diagram showing an ESCA observation result of a glass substrate surface on which no conventional surface treatment is performed.
5 is a diagram showing an ESCA observation result of the surface of a copper wiring board using the conventional glass substrate of FIG.
FIG. 6 is a diagram showing an ESCA observation result of a glass substrate surface subjected to a conventional argon plasma cleaning process.
7 is a diagram showing an ESCA observation result of the surface of a copper wiring board using the conventional glass substrate of FIG. 6. FIG.
FIG. 8 is a diagram showing an example of the configuration of a sputtering film forming apparatus used in the manufacturing method of the present invention.
FIG. 9 is a diagram showing an example of a structure of a sputter film forming chamber used in the manufacturing method of the present invention.
FIG. 10 is a process explanatory view showing an example of the production method of the present invention.
FIG. 11 is a process explanatory diagram illustrating an example of the manufacturing method of the present invention following FIG. 10;
FIG. 12 is a plan view illustrating an example of a thin film transistor.
13 is a cross-sectional view taken along line AA in FIG.
FIG. 14 is a diagram showing an example of a cross-sectional structure of a conventional copper wiring board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Substrate, 1a ... Silicon nitride alteration layer, 2 ... Copper wiring, 3 ... Gate wiring, 4 ... Source wiring, 5 ... Gate electrode, 6 ... Source electrode, 7 ... Drain electrode, 8 ... Pixel electrode, 9 ... Barrier metal layer, 10 ... Loading chamber, 11 ... Cleaning chamber, 12 ... Sputter deposition chamber, 13, 14,. Gate valve, 15, 17 ... substrate electrode, 16 ... counter electrode, 18 ... target electrode, 19 ... target, 20 ... copper thin film, 22 ... sputter deposition chamber, 25 35 ... high frequency power supply, 28 ... direct current power supply, 40 ... thin film transistor substrate, 80 ... thin film transistor, 81 ... pixel, 89 ... gate insulating film, 89a ... silicon nitride altered layer 90,92 ... Semiconductor active film, 91,93 ... O -Contact contact film, 94 ... Copper thin film, 96 ... Passivation film, 99 ... Contact hole

Claims (10)

SiO _{2 on} the surface of glass substrate, quartz substrate or silicon oxide film A copper wiring board comprising a copper thin film deposited through a silicon nitride altered layer containing 10% or more of SiNx bonds therein . Using a film forming apparatus having a cleaning chamber and a sputter film forming chamber, nitrogen gas alone or a mixed gas of nitrogen and argon is introduced into the cleaning chamber, and the surface of the glass substrate, quartz substrate or silicon oxide film is introduced. A method for producing a copper wiring board, comprising performing nitrogen plasma irradiation, performing reverse sputtering cleaning, and then forming a copper thin film by sputtering using argon gas in a sputtering film forming chamber. Nitrogen gas alone or a mixed gas of nitrogen and argon is introduced into the sputtering film formation chamber to irradiate the surface of the glass substrate, quartz substrate or silicon oxide film with nitrogen plasma, and then argon gas is used in the sputtering film formation chamber. A method of manufacturing a copper wiring board, wherein a copper thin film is formed by sputtering. 4. The method of manufacturing a copper wiring board according to claim 3, wherein a high-frequency current is applied only to a substrate side electrode on which a substrate on which the copper thin film is to be formed is placed at least during the nitrogen plasma irradiation. A method for manufacturing a copper wiring board. A method for producing a copper wiring board, comprising: irradiating a glass substrate, a quartz substrate or a silicon oxide film surface with nitrogen plasma and simultaneously forming a copper thin film by sputtering. 6. The method of manufacturing a copper wiring board according to claim 5, wherein a nitrogen gas alone or a mixed gas of nitrogen and argon is introduced into a sputtering film forming chamber at the beginning of film formation of a copper thin film to introduce a glass substrate, a quartz substrate, or silicon oxide. A copper thin film is formed by sputtering while irradiating the surface of the film with the nitrogen plasma, and then, in the latter stage of the formation of the copper thin film, argon alone gas is introduced into the sputtering film forming chamber to form the copper thin film by sputtering. A method for manufacturing a copper wiring board, comprising: 7. The method of manufacturing a copper wiring board according to claim 5, wherein at least the target electrode and the substrate electrode on which the substrate on which the copper thin film is to be deposited are placed at least during the nitrogen plasma irradiation. A method for manufacturing a copper wiring board, wherein: 7. The method of manufacturing a copper wiring board according to claim 5 or 6, wherein a direct current is applied to the target electrode and a high-frequency current is applied to the substrate electrode at least during the nitrogen plasma irradiation. Method. 8. The method of manufacturing a copper wiring board according to claim 7, wherein a high-frequency current having a frequency of 13.5 MHz or more is applied to the target electrode at least during the nitrogen plasma irradiation. 8. The method of manufacturing a copper wiring board according to claim 7, wherein the high frequency current applied to the target electrode has a frequency higher than the frequency of the high frequency current applied to the substrate electrode.

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