JP5288810B2 - Local plasma processing apparatus and processing method - Google Patents

Description

  The present invention is a plasma processing apparatus capable of generating a small-diameter plasma flow under atmospheric pressure, and further relates to a local etching processing method or thin film formation processing method of a sample surface using the generated plasma flow.

  In general, when circuit wiring is formed on an electronic circuit board, a conductive film as a wiring material or an insulating film as an interlayer insulating material is formed on the entire surface, and unnecessary regions are removed using a photolithography method and an etching method. Thus, a desired wiring or insulating film has been formed. However, these methods require a great deal of cost because an electronic circuit board is completed through many process steps, and are particularly suitable as a method for forming a wiring or an insulating film only in a very limited area on the circuit board. It wasn't a way.

  On the other hand, Patent Document 1 has been reported as a method of locally forming a thin film on a circuit board. This method is called a laser CVD method, in which a gas serving as a raw material for metal wiring is supplied to a desired region on a circuit board, and the raw material gas is decomposed by irradiating the region with laser light to deposit a metal thin film.

  Patent Documents 2 to 4 report methods for decomposing a source gas using plasma instead of laser light and forming the reaction product on an electronic circuit board. Specifically, a rare gas and a reactive gas are mixed and introduced into a reaction vessel having electrodes arranged in parallel and opposed to each other, plasma excitation is performed between the counter electrodes under atmospheric pressure, and the generated active species are In this method, a thin film is formed on a circuit board by transporting it in the direction of the board. Since this method can use a silicon atom-containing gas as a raw material gas, it is suitable for forming an insulating thin film or a semiconductor thin film rather than forming a metal foil film.

7-484967 JP-A-2005-262111 JP 04-358076 JP 04-015921 A

  However, since the laser CVD technique described in Patent Document 1 has a defect that the decomposition of the source gas largely depends on the absorption characteristics of the irradiated laser beam, the material that can be formed is often a metal thin film such as palladium. In addition to the problem that it is difficult to form an insulating thin film such as a silicon oxide film, it has a fatal defect that it is impossible to remove the material formed on the circuit board by etching.

  In addition, the plasma techniques described in Patent Documents 2 to 4 decompose the reactive gas in a reaction vessel (quartz) having a relatively large diameter using a high-frequency power source including microwaves as an excitation source, and generate generated active species. In this method, irradiation is performed uniformly and over a wide area toward the substrate.

  Therefore, a part of the generated active species has a problem that the decomposition efficiency of the reactive gas is reduced by adhering to the inner wall of the reaction vessel, or the plasma reaction in the reaction vessel becomes unstable, It must be said that it is difficult to stably form a thin film only in a desired region on the substrate using this technique.

  The present invention solves the above-mentioned problems, and forms a thin thin film in a desired region of the substrate surface using a small-diameter plasma flow generated under atmospheric pressure, or removes a part of the substrate by etching. It is an object of the present invention to provide a possible local plasma processing apparatus and a processing method thereof.

  The local plasma processing apparatus for achieving the above-described object of the present invention has an apparatus configuration including a plasma generation unit, a gas supply unit, and a plasma reaction unit. The plasma generating unit is configured by arranging a plasma generating narrow tube made of a dielectric and an electrode for supplying high frequency power from a high frequency power source via a matching network in an outer peripheral region of the narrow tube.

  Further, the plasma reaction part is provided with an open part at one end, and one end part of the narrow tube described above is inserted into the plasma reaction part from the opposite side of the open part. The plasma flow generated inside the narrow tube is released from this end, but the sample mounted on the substrate stage is placed on the extended line and facing the open part of the plasma reaction part. Yes.

The gas supply unit is composed of a first gas supply unit and a second gas supply unit, and the pipe of the first gas supply unit is connected to the other end of the narrow tube, and the plasma generation unit is connected to the second gas supply unit. It has the role of supplying 1 gas. Also, the piping of the second gas supply unit is directly inserted into the plasma reaction unit, and the supply port of the piping is arranged in the region intersecting the sample surface on the extension line of the above-mentioned narrow tube, The gas is arranged as close as possible to the surface of the sample on which the plasma treatment is performed.
Here, the first gas is an inert gas typified by Ar, He or the like, and is used for forming a plasma flow, and the second gas is a raw material gas for forming a thin film typified by silane, TEOS or the like. Although the etching gas is typified by chlorine or fluorocarbon, the gas species applicable in the present invention is not limited to the above specific examples.

The plasma of the inert gas is emitted from the end of the narrow tube inserted into the plasma reaction part toward the surface of the sample, and the plasma flow passes through the plasma electric field control part having an aperture that can pass through. Reach the sample surface. And the diameter of the plasma flow is controlled by the plasma electric field control part.
In addition, it is also possible to control the diameter of the plasma flow by providing plasma magnetic field control units on both sides of the sample with the plasma flow as the central axis.

  The outline of the processing apparatus configuration for forming a local plasma region on the surface of the sample has been described above. Next, a case where a sample is processed using this apparatus will be described.

  Plasma is generated by applying high-frequency power to the inert gas supplied from one end of the thin tube to the inside of the thin tube, and an opening of the plasma control unit disposed between the other end of the thin tube and the sample is provided. The plasma flow is reduced to a desired size by passing it, and the reactive gas supplied near the surface of the sample is decomposed using this to deposit the generated reaction product on the surface of the sample. . At this time, if a silicon atom-containing gas such as TEOS gas is used as the reactive gas, a silicon oxide film can be deposited on the surface of the sample.

  On the other hand, plasma is generated by applying high-frequency power to an inert gas supplied from one end of the narrow tube to the inside of the tube, and an opening of a plasma control unit disposed between the other end of the thin tube and the sample. The reaction product generated by decomposing the reactive gas supplied near the surface of the sample using this is reduced in diameter to a desired size by passing through the section so that the reaction product reacts on the surface of the sample. did. At this time, if the reactive gas used contains at least a chlorine or halogen gas, the reaction product serves to remove a part of the sample.

As described above, the process of generating and reducing the diameter of the plasma flow and the process of reacting with the source gas are separated, and the latter process is performed in the vicinity of the sample surface. It is possible to stably form a thin film in the region or remove a limited part of the sample.

Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 shows a schematic diagram of an inductively coupled local plasma processing apparatus according to a first embodiment of the present invention. The local plasma processing apparatus is roughly divided into a plasma generation unit 1, gas supply units 2 and 3, and a plasma reaction unit 4. The plasma generating unit 1 is configured by arranging a plasma generating thin tube 6 made of a dielectric and an electrode 9 for supplying high frequency power from a high frequency power source 7 via a matching network 8 on the outer peripheral region of the thin tube 6. ing.

  As a specific example, a quartz tube having an inner diameter of 1 mm and an outer diameter of 4 mm was used for the thin tube 6. Then, two copper electrodes 9 opposed to the electrode 9 for applying a predetermined high frequency power from the high frequency power source 7 (144 MHz, 200 W power source) to the thin tube 6 were provided on the outer periphery of the thin tube 6. In addition, when supplying high frequency electric power to the thin tube 1, it performed via the matching network 8 so that the reflected wave from the high frequency power supply 7 might become the minimum.

  In addition, although mentioned later, the piping 12 of the 1st gas supply part 2 which comprises a gas supply part is connected to the one end part of the thin tube 6, and the 1st gas is supplied to the inside of the thin tube 6. Then, after a desired high frequency power is applied from the high frequency power source 7, plasma is ignited using an igniter (not shown).

  In addition, at least the plasma generation unit 1, the narrow tube 6, the high-frequency applying electrode 9 and the plasma reaction unit 4 are configured to move together, and when the distance from the sample 11 is varied, these are moved simultaneously. .

  Next, the plasma reaction part 4 is provided with an open part 5 at one end, and one end of the narrow tube 6 is inserted into the plasma reaction part 4 from the opposite side of the open part 5. A plasma flow due to the first gas generated inside the narrow tube 6 is emitted from the end toward the opening 5. A sample 11 mounted on the substrate stage 10 is disposed on the extended line of the thin tube 6 so as to face the open part 5 of the plasma reaction part 4.

  The pipe 13 of the second gas supply unit 3 constituting the gas supply unit is directly inserted into the plasma reaction unit 4, and the supply port 14 of the pipe 13 is on the extension line of the narrow tube 6 and is the sample 11. It is arranged as close as possible to the area that intersects the surface.

  Here, the first gas is an inert gas typified by Ar, He or the like, and is used to form the plasma flow 15 inside the plasma reaction chamber 4. The second gas is a raw material gas for thin film formation typified by silane, TEOS, or the like, or an etching gas typified by chlorine, fluorocarbon, or the like. It is not limited to a specific example.

  Hereinafter, it will be described more specifically on the assumption that a sample 11 is an electronic circuit board and a protective film or insulating film made of a silicon oxide film is locally formed thereon.

  For the generation of the plasma flow 15, argon gas (hereinafter referred to as Ar) was used as the first gas (inert gas), and TEOS (tetraethoxysilane) gas was used as the second gas (reactive gas) for forming the insulating film. These two kinds of gases are supplied to the inside of the plasma reaction unit 4 from gas pipes (first pipe 12 and second pipe 13) of different systems.

  Here, the importance of individually supplying the first gas and the second gas and reacting them in the region close to the surface of the sample 11 is as follows. That is, (1) When a second gas (TEOS gas) for forming a thin film is introduced into the narrow tube 6 and plasma is generated there, active species (radicals) from the TEOS gas are deposited inside the narrow tube 6. As a result, it is difficult to maintain a stable plasma. (2) The lifetime of active species and ions in plasma that contribute to the formation of a thin film is relatively short (the average free path of active species is several tens of times under atmospheric pressure). There is a problem that the property of the active species changes before the active species is transported to the surface of the sample 11.

  In order to avoid this and form a thin film having desired characteristics on the surface of the sample 11 (for example, the dielectric breakdown field strength of the silicon oxide film is 500 MV / m or more), as described above, it is used for plasma formation. Ar gas and TEOS gas used for forming a thin film are individually supplied, and the TEOS gas is reacted in the vicinity of the surface of the sample 11 using the plasma flow 16 of Ar gas, and the activated species of the generated TEOS gas is immediately converted into the sample 11. It is extremely important to transport it on the surface of the silicon and contribute to the formation of a silicon oxide film.

  By the way, since TEOS gas is liquid at room temperature, TEOS gas must be supplied while bubbling TEOS gas using an inert gas such as Ar gas or nitrogen gas. At this time, in order to prevent the TEOS gas from adhering in the second pipe 13 before reaching the plasma reaction unit 4 from the second supply unit 3, a heater (such as a ribbon heater) having a temperature adjustment function ( It is necessary to attach the second pipe 13 to the second pipe 13 and to keep the second pipe 13 itself at about 100 ° C. Further, in order to efficiently supply the TEOS gas, it is effective to keep the second gas supply unit 3 itself at about 100 ° C.

  The flow rates of the plasma forming Ar gas and the thin film forming TEOS gas are controlled by mass flow controllers 12a and 13a (hereinafter referred to as MFC) installed in the pipes 12 and 13, respectively. The flow rate of the inert gas (Ar gas) used for bubbling the TEOS gas is performed using the MFC 13b connected to the first gas supply unit 2, and is supplied into the plasma reaction unit 4 together with the TEOS gas. In addition, although the stainless steel 1/4 inch pipe is used for the pipes 12 and 13, it can be narrowed down by using a 1/8 inch pipe or the like inside the plasma reaction unit 4 and can be supplied limited to the vicinity of the surface of the sample 11. I made it.

  The TEOS gas supplied into the plasma reaction unit 4 is processed by an exhaust facility and a detoxification facility (not shown) through a vacuum control unit 20 connected to the plasma reaction unit 4. Further, the pressure in the plasma reaction unit 4 is controlled using a pressure gauge built in the vacuum control unit 20, but a part of the TEOS gas is prevented from being dissipated from the open part 5 of the plasma reaction unit 4. Therefore, the pressure in the plasma reaction unit 4 is adjusted by the vacuum control unit 20 so as to be lower than the atmospheric pressure.

Next, an Ar plasma discharge control method, a plasma flow diameter reduction method, and a thin film formation method will be described in more detail using the local plasma processing apparatus of the present invention.
(1) Ar Plasma Discharge Control Method In FIG. 1, Ar gas is introduced from the first gas supply unit 2 into the narrow tube 6 as a plasma generation gas at a rate of 1 L / min. Then, an input power of 70 W was applied from the high frequency power source 7 to the electrode 9 via the matching network 8. The Ar gas plasma is performed using an igniter (not shown). When the reflected wave to the high frequency power source 7 is large and the plasma discharge is unstable, the matching network 8 is set so that the reflected wave is minimized. Use to adjust.

  The plasma discharge state can be known by analyzing plasma emission observed from an observation window (not shown) installed in the plasma reaction unit 4 using a spectroscopic measurement device. In this example, Ar emission emission lines 696 nm and 750 nm were measured, and the stability of the plasma was judged from the ionization state. Moreover, the inside of the plasma reaction part 4 was measured using the infrared thermometer which has a sensitivity in a wavelength range of 5-15 micrometers, and the temperature of the sample 11 and the thin tube 6 was measured.

  Under the above discharge conditions, an Ar plasma flow 15 of about 10 mm from the tip of the thin tube 6 toward the sample 11 was observed. The diameter of the plasma flow 15 gradually tapered from the tip of the thin tube 6 and was about several hundreds μm at the tip of the plasma flow 15. The temperature of the plasma flow 15 reaches 660 ° C. or higher at which the aluminum wiring formed on the glass substrate easily melts within 1 mm from the tip of the thin tube 6, and the aluminum wiring no longer melts near the tip of the plasma flow 15. It was confirmed that the temperature of the plasma flow 15 was reduced to an extent.

  Further, when the Ar gas flow rate was increased to 3 L / min without changing the high frequency power, the length of the plasma flow 15 increased to 15 mm, but the temperature of the plasma flow 15 was within 1 mm from the tip of the narrow tube 6. Even if it existed, the aluminum wiring was not melted. When the flow rate of Ar gas supplied to the narrow tube 6 is changed in the range of 1 to 10 L / min and the input power of the high-frequency power source 7 is changed from 30 to 200 W, the trading of the sample 11 is performed by the trading company of the plasma flow 15. The surface temperature could be controlled in the range of 50 to 800 ° C.

(2) Plasma Flow Shape Control Method The diameter of the plasma flow generated inside the plasma reaction unit 4 can be achieved by further reducing the inner diameter of the narrow tube 6 from the above 1 mm. However, when the inner diameter of the narrow tube 6 is 0.5 mm or less, the plasma itself generated in the narrow tube 6 becomes unstable.

  Therefore, as shown in FIG. 1, the diameter control of the plasma flow 15 using the electric field control unit 17 was examined. That is, the electric field control unit 17 has an opening 16 through which the plasma flow 15 emitted from the tip of the thin tube 6 can sufficiently pass, and is disposed between the thin tube 6 and the sample 11 described above.

  FIG. 2 is a diagram schematically illustrating how the diameter of the plasma flow 15 emitted toward the sample 11 is changed by the electric field control unit 17. FIG. 2A shows a case where a positive potential is applied to the electric field control unit 17 using the electric field control power supply 18, and a force directed toward the inside of the electric field control unit 17 acts on the positive ions in the Ar plasma flow 15, and as a result. As a result, the diameter of the plasma flow 15 is reduced. On the other hand, FIG. 2 c shows a case where a negative potential is applied to the electric field control unit 17, and a force directed toward the outside of the electric field control unit 17 acts on the cations in the Ar plasma flow 15, resulting in the diameter of the plasma flow 15. Is enlarged. 2B is a case where the electric field control unit 17 is grounded, and the diameter of the plasma flow 15 emitted from the tip of the narrow tube 6 gradually becomes tapered due to collision with the atmosphere.

  FIG. 3 is an explanatory diagram for controlling not only the diameter of the plasma flow 15 but also the shape thereof using a plurality of electric field controllers 17a, 17b, and 17c. In FIG. 3, the electric field controllers 17a, 17b, and 17c are arranged in that order between the narrow tube 6 and the sample 11, and the voltages applied to the electric field controllers 17a, 17b, and 17c are electric field control power supplies 18a, 18b, Each is applied independently using 18c.

  For example, when the voltage applied to the electric field control units 17a, 17b, and 17c is increased in the order of the electric field control power supplies 18a, 18b, and 18c (a potential gradient is formed from the electric field control units 17a to 17c), the electric field control is performed. The force for moving the cations in the plasma flow 15 inward according to the portions 17a to 17c is increased, and as a result, the diameter of the plasma flow 15 is controlled to be narrower as it passes through the electric field control portions 17a, 17b, and 17c. . In this case, not only the diameter control of the plasma flow 15 but also the length that the plasma flow 15 is maintained (the discharge length of the plasma flow) is simultaneously extended.

  On the other hand, the voltage applied to 17c is reduced compared to the electric field control unit 17a, and the incident intensity of Ar ions incident on the surface of the sample 11 is suppressed by forming a potential gradient from the electric field control unit 17c to 17a. It is possible to reduce damage to the sample 11 due to ion bombardment.

  Although FIGS. 2 to 3 show the plasma flow shape control method using the electric field control unit 17, it is effective to use a shielding plate having an opening smaller than the diameter of the plasma flow 15 instead of the electric field control unit 17. is there. However, since the shielding plate is directly exposed to the plasma flow 15, it is necessary to use a material excellent in etching resistance against Ar plasma, for example, a ceramic material such as quartz or aluminum oxide.

(3) Plasma density control method The density of Ar plasma formed inside the narrow tube 6 is determined by the high-frequency power supplied from the high-frequency power source 7, the flow rate of Ar gas supplied from the first gas supply unit 2, and the like. The And the density falls as it radiates | emits from the front-end | tip part of the thin tube 6 to the inside of the plasma reaction part 4. FIG. However, in order to decompose the TEOS gas or the like using the plasma flow 15 radiated into the plasma reaction unit 4 and use it for forming a silicon oxide film, a decrease in the density of the plasma flow 15 is suppressed as necessary. It is important to.
FIG. 4 is an explanatory diagram centered on the plasma reaction unit 4 of the local plasma processing apparatus shown in FIG. The difference from FIG. 1 is that a plasma magnetic field controller (annular structure) for controlling the plasma density of the plasma flow 15 is further installed. That is, plasma magnetic field control units 19a and 19b for controlling the diameter and density of the plasma flow 15 are provided on both sides of the sample 11 with the plasma flow 15 as a central axis.

  Between the plasma magnetic field control unit 19 a disposed inside the plasma reaction unit 4 and the plasma magnetic field control unit 19 b disposed below the sample 11, the direction of the sample 11 or the opposite direction with the plasma flow 15 as the central axis. Magnetic field lines are formed, and the plasma flow 15 is confined inside the cylindrical magnetic field lines. As a matter of course, the strength of the magnetic force lines generated by the plasma magnetic field control units 19a and 19b is increased, and the confinement effect of the plasma flow 15 is increased. As a result, the diameter of the plasma flow 15 is controlled to be reduced.

  The example shown in FIG. 4 shows only one set of the plasma magnetic field control units 19a and 19b. However, the plasma flow control unit 19a and 19b is further divided and appropriately controlled to control the plasma flow as in the case of the plasma electric field control unit shown in FIG. 15 can control the behavior of electrons. In FIG. 4, the plasma magnetic field control unit 19 a is arranged between the plasma electric field control unit 17 and the tip of the thin tube 6, but the same effect can be obtained by arranging it between the plasma electric field control unit 17 and the sample 11. can get.

(4) Thin Film Formation in Local Region Using the local plasma processing apparatus shown in FIG. 1 above, an attempt was made to form an insulating film (silicon oxide film) using Ar gas and TEOS gas. As an example, the sample 11 uses a glass substrate, the input power of the high-frequency power source 7 which is a film forming condition is 70 W, the flow rate of Ar gas supplied from the first gas supply unit 2 to the narrow tube 6 is 3 L / min, the second The amount of TEOS gas supplied from the gas supply unit 3 to the vicinity of the surface of the sample 11 was controlled by the mass-free controller MFC 13a with the flow rate of Ar gas used for bubbling, and the flow rate was set to 0.15 L / min. The distance from the narrow tube 6 to the surface of the sample 11, that is, the length of the Ar plasma flow was adjusted to be about 15 mm.

  It was confirmed by Raman spectroscopy that a silicon oxide film (film thickness: about 1 μm) was formed on the surface of the sample 11 in a region having a diameter of about 100 μm. In general, when a silicon oxide film is deposited by thermal decomposition of TEOS gas, it is necessary to preheat the sample 11 to 600 ° C. or more in advance. In the above example, the surface temperature of the sample 11 is about 300. It was revealed that the film could be formed at about ℃ (measured with an infrared thermometer).

  This is decomposed by the Ar plasma flow 15 by forming the Ar plasma flow 15 and supplying the TEOS gas independently, and by supplying the TEOS gas directly to a region where the Ar plasma flow 15 intersects the sample 11. It is considered that this is because the active species of the TEOS gas reaches the surface of the sample 11 before the end of its life and contributes to the formation of a thin film. The obtained silicon oxide film has a dielectric breakdown characteristic of about 500 MV / m, which is as good as a general thermal oxide film.

Next, an example of forming a semiconductor thin film (amorphous silicon film) will be described.
SiH ₂ Cl ₂ (dichlorosilane) gas was used as a reactive gas supplied from the second gas supply unit 3 into the plasma reaction unit 4. As described above, since the mean free path of molecules is about several tens of nanometers under atmospheric pressure, a reaction between a reactive gas and plasma is performed near the surface of the sample 11 in order to form a dense thin film. It is desirable to quickly recombine active species (radicals) on the surface of the sample 11.

The Ar gas flow rate and high frequency power were the same as in the case of forming the silicon oxide film described above, and a plasma flow 15 of about 15 mm was formed from the tip of the narrow tube 6 into the plasma reaction unit 4. The position of the sample 11 was set approximately 1 mm away from the tip of the plasma flow 15. The flow rate of SiH ₂ Cl ₂ gas was set to 0.2 L / min, and hydrogen gas was further mixed to several to several tens of percent and supplied from the second pipe supply port 14 in the vicinity where the plasma flow 15 and the sample 11 intersected. This is because the mixing of hydrogen gas promotes the impurity dissociation reaction in the silicon film and forms a high-quality thin film with fewer impurities.

In addition, SiH ₂ Cl ₂ gas was intermittently supplied to further improve the quality of the formed thin film. That is, after supplying SiH ₂ Cl ₂ gas for 5 seconds, supply of SiH ₂ Cl ₂ gas was stopped for the next 5 seconds. During this stop period, the surface of the sample 11 was subjected to plasma treatment with the Ar plasma flow 15. This was intended to promote the formation of a network between atoms of the deposited amorphous silicon film by continuing the irradiation of the plasma flow 15.

  As a result, an amorphous silicon film (with a film thickness of about 0.5 μm) is formed on the sample 11 in a diameter range of about 1 mm, and the current ratio when turning on / off light irradiation, which is a basic characteristic of an amorphous silicon film, is generally A numerical value comparable to that of an amorphous silicon film formed by using a parallel plate type plasma CVD method, which is a typical technique, was obtained.

(5) Etching treatment in local region As described above, a silicon oxide film can be locally formed on the sample 11 by supplying the TEOS gas from the second gas supply unit 3 in FIG. I explained that.

Therefore, CF ₄ gas was supplied from the second gas supply unit 3 into the plasma reaction unit 4 instead of the TEOS gas. The flow rate of Ar gas, high frequency power, and flow rate of CF ₄ gas were performed under substantially the same conditions as in the formation of the silicon oxide film. As a sample 11, a silicon nitride film (film thickness of about 1 μm) was formed on a glass substrate. In addition, it is desirable to use a material having excellent etching resistance against CF ₄ gas for the thin tube 6, and here, a ceramic tube (inner diameter of about 1 mm) was used.

  As a result, it was confirmed that the silicon nitride film formed on the sample 11 was etched in a bowl shape within a range of about several hundred μm in diameter.

As described above, the example in which Ar gas is used as the plasma-based product gas, TEOS gas is used as the reactive gas for thin film formation, and CF ₄ gas is used as the etching gas has been described. It is not limited. For example, He gas is used as a plasma generation gas, SiH ₄ gas or SiH ₂ Cl ₂ gas is used as a reactive gas for forming a thin film, and O ₃ gas or Cl ₂ gas is used as an etching gas. It is possible to use the gas used in the above.

(Second embodiment)
Next, as a second embodiment of the present invention, a defect correction of a liquid crystal display element performed using the above-mentioned local plasma processing apparatus will be described.
In general, a liquid crystal display device (not shown) includes a plurality of pixel portions formed on one glass substrate (TFT substrate) and a plurality of color filter portions formed on the other glass substrate (color filter substrate). Are arranged such that the pixel portion and the color filter portion are opposed to each other, and a liquid crystal is sandwiched therebetween.

  The pixel portion is formed through the following steps. That is, a gate wiring is formed on a glass substrate, and a gate insulating layer is formed thereon. Then, an island-like semiconductor layer (amorphous silicon film) is formed on the gate insulating layer in a region where the gate electrode connected to the gate wiring is located. A drain wiring connected to one end of the semiconductor layer via an electrode (drain electrode) is formed in a direction crossing the gate wiring. A source electrode is formed at the other end of the semiconductor layer, and the source electrode and the transparent electrode are connected through a contact hole formed through a protective film formed so as to cover the whole. ing. One pixel portion is constituted by a thin film transistor portion (TFT) that is surrounded by two drain wirings and two gate wirings and is composed of a gate electrode, a drain electrode, a source electrode, a transparent electrode, and a semiconductor layer.

  The liquid crystal display element controls the amount of light passing through the pixel portion by changing the voltage generated in the transparent electrode in accordance with the on / off state of the thin film transistor portion and changing the orientation of the liquid crystal in accordance with the change.

As described above, the outline of the liquid crystal display device has been described. However, since the liquid crystal display device is manufactured through a plurality of film forming processes (wirings, semiconductor layers, electrodes) and etching processes, a short circuit between wirings due to inconveniences such as foreign matter mixed in the process and a photomask Problems such as disconnection of wiring and defective shape of the semiconductor layer are caused, and these are considered to be factors that cause a decrease in characteristics and quality of the liquid crystal display device and also a manufacturing yield. Accordingly, it is considered to be extremely important to correct the above-described defective portion generated in a very limited area of the liquid crystal display device as necessary.
Therefore, an example of correcting the disconnection of wiring, which is one of fatal defects, performed using the local plasma processing apparatus of the present invention and a method for correcting the above-described defects in the manufacturing process will be described below.

  First, an example of correcting a partially missing part of the gate wiring will be described. FIG. 5 is a process diagram for explaining the process of correcting the disconnection of the gate wiring. In FIG. 5A, a gate wiring 102 made of Cr or the like is formed on a glass substrate 101. A gate insulating film 103 made of a silicon nitride film is formed on the gate wiring 102, and a protective film 104 made of a silicon nitride film or a silicon oxide film is further formed thereon. However, as a result of the final lighting test of the liquid crystal display device, it was found that the disconnection portion 105 of the gate wiring 102 was caused due to adhesion of foreign matters in the formation process of the gate wiring 102. In this state, it is impossible to supply a signal to a part of the gate wiring, and it has been disposed of as a “line defect product” that is fatal as a so-called liquid crystal display device.

Therefore, an attempt was made to correct the disconnection portion 105 using the local plasma processing apparatus of the present invention. First, as shown in FIG. 5B, the disconnection part 105 is arranged at the tip position of the plasma flow 15 shown in FIG. 1, and CF ₄ gas is introduced into the plasma reaction part 4 from the second gas supply part 3. Supplied. Then, the protective film 104 and the gate insulating film 103 covering the upper portion of the disconnection portion 106 were sequentially etched to expose the surface of the glass substrate 101, thereby forming an etching removal portion 107. Note that the opening of the protective film 104 and the gate insulating film 103 needs to be larger than the disconnected portion 105 of the gate wiring 102.

Next, as shown in FIG. 5 (c), the reactive gas supplied from the second gas supply unit 3 is switched from CF ₄ gas to (CH ₃ ) ₃ Al gas (trimethylaluminum gas) and supplied, The Al wiring forming portion 107 was formed so that part of the gate wiring 102 overlapped. Here, (CH ₃ ) ₃ Al gas is used, but any metal atom-containing gas having low resistance characteristics may be used.

  Next, as shown in FIG. 5D, the insulating film forming region is formed so as to fill the interior of the wiring forming portion 107 by changing the kind of the reactive gas supplied from the second gas supplying portion 3 again. 108 was formed. Here, the reactive gas used for forming the insulating film is TEOS gas, and the formed insulating film 108 is a silicon oxide film.

  In this way, the broken portion of the gate wiring, which has been a fatal defect for the liquid crystal display device, is repaired using the local plasma processing apparatus of the present invention, and a new function can be restored.

  Next, various defects that occur in the manufacturing process of the liquid crystal display device, for example, a short circuit between the wirings (defect pattern A), a foreign substance (defect pattern B) mixed between laminated films such as wirings and insulating films, and disconnection of the wirings Regarding (defect pattern C), a correction procedure during the manufacturing process will be described.

  FIG. 6 is a diagram summarizing the flow of the TFT formation process and the flow of inspection / classification of defects and the repair thereof. As described above, in the TFT forming process, a desired circuit pattern and TFT are formed through a thin film forming process 201 for forming various wirings, semiconductor films and insulating films, a photolithography process 202 and an etching / resist peeling process 203. Next, in the TFT array inspection process 204, various defects are detected using an appearance inspection device, an array tester, or the like. The defect information detected by the inspection device and the defect position information are received via the network of the production line, and the stage on which the substrate on which the defect is detected is driven based on the information, and the optical system of the correction device The defect position is reproduced in the field of view (defect information collecting step 205). Thereafter, the defect is reviewed using an observation camera mounted on the correction device (review step 206), and detailed discrimination of defect types such as color, planar shape, height information, etc. is performed (defect type discrimination step 207). .

  For example, the entire observation optical system is moved in the Z direction perpendicular to the surface on which the TFT substrate of the stage is placed by an automatic focusing mechanism to focus on the TFT substrate surface. The substrate may be moved in the Z-axis direction by the substrate stage. Then, after obtaining the height information of the defect from the image captured by the observation camera, the defect is corrected using the above-described local plasma generation apparatus.

(Defect pattern A correction 208)
When the defect pattern A208, which is a short-circuit defect between wirings, is detected in the defect type discrimination step 207, Ar gas is supplied to the narrow tube 6 from the first gas supply unit 2 in the local plasma generation apparatus shown in FIG. In addition, an Ar plasma flow 15 is formed by applying high-frequency power from the high-frequency power source 7 to the Ar gas. The plasma flow 15 is applied to the pattern A 208 to remove an extra region between the wirings.
It should be noted that a gas capable of etching the wiring material may be appropriately selected from the second gas supply unit 3 and supplied to the vicinity of the defect pattern A208 to remove excess wiring by etching.

  Thereafter, the portion where the wiring is removed is inspected. If the wiring removal is insufficient, the plasma processing conditions are changed and the processing is performed again. If it is determined that the removal of the excess wiring is sufficient, a protective film is formed on the surface in the vicinity of the processed wiring (protective film forming step 211) to complete defect correction, and the TFT substrate is moved to the next step. Transport.

(Defect pattern B correction 209)
Next, a correction method in the case where a foreign matter: convex defect (defect pattern B) mixed between laminated films such as wirings and insulating films is detected in the defect type discrimination step 207 will be described.
Here, an example is shown in which foreign matter (convex defects) is present on the gate wiring of the TFT element. When forming a wiring film, a convex defect occurs due to, for example, a splash defect in which a metal melt is deposited by sputtering, or a foreign matter is mixed during film formation. When the height of this convex defect is large, it penetrates the gate insulating film and protective film formed on it and comes into contact with the transparent counter electrode formed on the color filter substrate. It is necessary to remove the convex defect at the earliest possible stage in order to reduce the characteristic defect.

  First, in order to remove the protective film (if necessary, the gate insulating film) covering the foreign matter, Ar gas is supplied from the first gas supply unit 2 in the local plasma generating apparatus shown in FIG. Further, Ar plasma flow 15 is formed by applying high frequency power from the high frequency power source 7 to Ar gas. Then, a gas capable of etching the protective film is appropriately selected from the second gas supply unit 3 and supplied to the surface of the protective film where the convex defects are present, and the protective film is removed by etching. When the protective film is a silicon nitride film, chlorine fluoride gas or chlorine gas is used as the gas supplied from the second gas supply unit 3. If removal of the protective film is insufficient, the plasma conditions are optimized. Next, the gate insulating film located under the protective film is similarly removed. Then, when the convex defect is exposed on the surface, the gas supply from the second gas supply unit 3 is interrupted, and the above convex shape is formed using Ar plasma by the Ar gas supplied from the first gas supply unit 2. Remove defects.

Although it is possible to remove the protective film and the convex defect at once using Ar plasma, the material to be removed may be scattered around due to the difference in the material of the protective film and the convex defect. As described above, it is desirable to remove them separately.
Thereafter, a protective film (a gate insulating film is also formed if necessary) is formed again at the repaired portion (protective film forming step 211), and the correction of the convex defect is completed.

(Defect pattern C correction 210)
In the correction 209 of the defect pattern B described above, the wiring itself is often missing when a convex defect exists on the wiring. In such a case, the defect pattern C correction 209 described here is continued.

Since details of the wiring disconnection correction have been described with reference to FIG. 5, a procedure when a wiring disconnection (defect pattern C) is detected in the defect type discrimination step 207 will be described here.
First, the protective film in the region where the disconnection of the wiring is generated is removed over a region wider than the disconnection region. That is, Ar gas is supplied to the thin tube 6 from the first gas supply unit 2 in the local plasma generation apparatus to form the Ar plasma flow 15. Then, the protective film is removed from the second gas supply unit 3 using a chlorine fluoride gas or a chlorine gas capable of etching the protective film (here, a silicon nitride film). If removal of the protective film is insufficient, plasma conditions are optimized and plasma treatment is performed until a part of the wiring is exposed on the surface.

  Next, the wiring is formed so as to cover a part of the wiring described above with a gas containing a metal having high conductivity from the second gas supply unit 3 instead of chlorine fluoride gas or chlorine gas. After confirming the connection of the wiring correction portion, a protective film is formed again on the correction portion, and the wiring disconnection correction is completed.

  As described above, the use of a local plasma processing apparatus can be applied not only to the removal of foreign matter but also to various uses such as the removal of a protective film and an insulating film and the connection of wiring. In particular, when applied to a TFT substrate of a liquid crystal display device, it is possible to repair a fatal defect of the liquid crystal display device such as a short circuit between wirings, a foreign substance existing in an interlayer film, or a disconnection of the wiring.

  In the present invention, an example using a 144 MHz high frequency power supply has been described, but the present invention is not limited to this.

  A plasma flow constricted to a diameter of several hundreds of micrometers is stably irradiated onto the sample surface, and various reactive gases are supplied between the plasma flow and the sample surface to achieve local etching and formation of a high-quality thin film. This makes it possible to revive products that have been disposed of in the past, which is advantageous for industrial use and environmental protection.

It is the schematic for demonstrating a local plasma processing apparatus. It is a figure for demonstrating the diameter control of the plasma flow by an electric field control part. (A) is a case where a positive voltage is applied to the electric field controller, (b) is a case where the electric field controller is installed, and (c) is a case where a negative voltage is applied to the electric field controller. It is a figure for demonstrating the diameter control of the plasma flow using several electric field control. It is the schematic for demonstrating the local plasma processing apparatus which added the magnetic field control part. It is a figure for demonstrating an example of the disconnection correction of wiring. (A) is a schematic diagram for explaining the disconnection portion of the wiring, (b) is a schematic diagram for explaining the removal of the protective film and the gate insulating film, (c) is a schematic diagram for explaining the wiring formation, (D) is the schematic for demonstrating insulating film formation. It is a flowchart for correcting a general TFT formation process and various defects generated in the process using a local plasma processing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plasma production | generation part, 2 ... 1st gas supply part, 3 ... 2nd gas supply part, 4 ... Plasma reaction part, 5 ... Opening part, 6 ... Narrow tube , 7 ... high frequency power supply, 8 ... matching network, 9 ... electrode, 10 ... substrate stage, 11 ... sample, 12 ... first pipe, 12a ... mass flow controller, 13 ... 2nd piping, 13a ... Mass flow controller, 14 ... 2nd piping supply port, 15 ... Plasma flow 16 ... Opening, 17, 17a, 17b, 17c ... Plasma electric field control 18, 18 a, 18 b, 18 c... Electric field control power source, 19 a, 19 b... Plasma magnetic field control unit, 20... Vacuum control unit, 101... Glass substrate, 102. 103 ... Gate insulating film, 104 Protective film 105 ... Disconnection part 106 ... Etching removal part 107 ... Wiring forming part 108 ... Insulating film forming part 201 ... Thin film forming process 201 ... Photolitho process , 203 ... Etching, peeling process, 204 ... TFT array inspection process, 205 ... Defect information collection process, 206 ... Defect review process, 207 ... Defect type discrimination process, 208 ... Defects Pattern A correction, 209... Defect pattern B correction, 210... Defect pattern C correction, 211.

Claims (8)

A local plasma processing apparatus comprising a plasma generation unit, a first gas supply unit, a second gas supply unit, and a plasma reaction unit having an open part,
The plasma generating unit is provided with a plasma generating capillary made of a dielectric, disposed in the peripheral region of the capillary tubes, and electrodes for supplying a high frequency power through a matching network from the high-frequency power source, one of said capillary Is inserted into the plasma reaction part from the facing side of the open part of the plasma reaction part,
The sample mounted on the substrate stage is arranged in the open part of the plasma reaction part,
The piping of the first gas supply unit is connected to the other end of the narrow tube,
The piping of the second gas supply unit is inserted into the plasma reaction unit,
In the plasma reaction part, between the narrow tube and the sample, there is an opening through which the plasma flow emitted from the end of the narrow tube can pass, and for controlling the diameter of the plasma flow Place the plasma electric field controller,
The gas supplied from the first gas supply unit is an inert gas,
The gas supplied from the second gas supply unit is TEOS gas,
A heater with a temperature adjustment function is attached to the pipe of the second gas supply unit,
The pipe supply port of the second gas supply unit is arranged so as to supply TEOS gas to a region intersecting with the sample on an extension line of the thin tube, and a plasma flow is formed in the intersecting region. A TEOS gas is supplied from the pipe supply port independently of the local plasma processing apparatus. The TEOS gas supplied from the second gas supply unit is bubbled by the inert gas from the first gas supply unit.
The local plasma processing apparatus according to claim 1.   The local plasma processing apparatus according to claim 1, wherein a plurality of the plasma electric field control units are arranged in an emission direction of the plasma flow.   The local plasma processing apparatus according to claim 3, wherein a potential gradient is formed in the plasma electric field control unit in the plasma flow emission direction or in the opposite direction.   The local plasma processing apparatus according to claim 1, further comprising a plasma magnetic field control unit for controlling a diameter and density of the plasma flow on both sides of the sample with the plasma flow as a central axis.   The local plasma processing apparatus according to claim 1, wherein the plasma reaction unit includes a vacuum control unit for maintaining the inside of the plasma reaction unit in a negative pressure state. The local plasma processing apparatus according to claim 1, wherein the gas supplied from the first gas supply unit is an argon gas . Plasma is generated by applying high frequency power to an inert gas supplied from one end of the capillary to the inside of the capillary,
The diameter of the plasma flow is reduced by passing through the opening of the plasma control unit arranged between the other end of the thin tube and the sample ,
TEOS gas is supplied to the region where the plasma flow and the sample intersect, independently of the formation of the plasma flow,
A local plasma processing method, wherein a silicon oxide film is deposited on the surface of the sample by decomposing TEOS gas .

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