TW201816885A - Plasma etching method and plasma etching system - Google Patents

Abstract

[Problem] When the source electrode and the drain electrode are formed by etching a Ti / Al / Ti laminated film with a chlorine-containing gas plasma, the generation of fine particles can be suppressed, and furthermore, the underlying oxide semiconductor film can be suppressed Lost technology. [Solution] In the first plasma etching apparatus, use a gas containing chlorine to perform the first plasma etching on the Ti film and the Al film on the Ti / Al / Ti laminated film, and then use the second plasma etching apparatus. fluorine-containing gas to a lower Ti / Al / Ti laminated film of a Ti film for the first 2 plasma etching, and then, by the second plasma etching apparatus using a plasma of O ₂ gas or O ₂ gas and fluorine-containing gases Plasma, after treatment to suppress corrosion.

Description

Plasma etching method and plasma etching system

[0001] The present invention relates to a plasma etching method and a plasma plasma etching system.

[0002] A thin film transistor (TFT: Thin Film Transistor) used in a FPD (Flat Panel Display) is a gate electrode or a gate insulating film, a semiconductor layer, etc., which are patterned on a substrate such as a glass substrate. One side is sequentially laminated and formed. [0003] For example, when manufacturing a TFT with a bottom gate side structure of a channel etching type, a gate electrode, a gate insulating film, and an oxide semiconductor film are sequentially formed on a glass substrate, and then on the oxide semiconductor film, A metal film is formed, and then the metal film is etched by the plasma to form a source electrode and a drain electrode accordingly. As a metal film used as a source electrode and a drain electrode, a Ti / Al / Ti laminated film is often used. As an etching gas in the case, a chlorine-containing gas such as Cl ₂ gas is used (for example, Patent Documents 1 and 2). . [0004] Further, Patent Document 1 describes that as a countermeasure against corrosion of an electrode using a chlorine-containing gas, there is a fluorine-based system that supplies O ₂ gas, O ₂ gas, CF ₄ gas, and the like to the chamber after the etching with the chlorine gas. gas. [0005] Patent Document 2 describes that after the Ti / Al / Ti laminated film is etched by Cl ₂ gas, O ₂ gas is supplied into the chamber, and the resist film damaged by the etching is removed accordingly. [Prior Art Document] [Patent Document] [0006] [Patent Document 1] Japanese Patent Laid-Open No. 2015-173159 [Patent Document 2] Japanese Patent Laid-Open No. 2015-76487

[Problems to be Solved by the Invention] [0007] However, after the Ti / Al / Ti laminated film is etched with Cl ₂ gas, O ₂ gas, or O ₂ gas and CF _{4 are} introduced into the chamber, For example, a large amount of particles are generated by reacting an Al-containing compound generated by etching with an O ₂ gas or a CF ₄ gas. [0008] In addition, when the Ti / Al / Ti laminated film is etched by a chlorine-containing gas such as Cl ₂ gas, the base oxide semiconductor film is etched at the time of overetching, and the loss of the oxide semiconductor film increases. . [0009] Therefore, the present invention is to provide a source electrode and a drain electrode formed by etching a Ti / Al / Ti laminated film with a chlorine-containing gas plasma, thereby suppressing the generation of particles, and further, suppressing the substrate. A plasma etching method for loss of an oxide semiconductor film is a problem. Furthermore, it is an object to provide a plasma etching system that performs such a plasma etching method. [Means for Solving the Problems] [0010] In order to solve the above problems, a first aspect of the present invention is to provide a plasma etching method including a semiconductor film made of an oxide semiconductor, and formed on the semiconductor film. A substrate of a Ti / Al / Ti laminated film formed by laminating a lower Ti film, an Al film, and an upper Ti film. Plasma etching of the above Ti / Al / Ti laminated film. Features of the plasma etching method The process includes: carrying a substrate into a processing container of a first plasma etching apparatus, and performing a first plasma etching process on the upper Ti film and the Al film of the Ti / Al / Ti laminated film using a chlorine-containing gas; Next, the substrate after the first plasma etching is carried into a processing container of a second plasma etching apparatus, and a second plasma is performed on the lower Ti film of the Ti / Al / Ti laminated film using a fluorine-containing gas. etching works; and maintaining the holding of the rear of the second plasma etching of the substrate in a state in which the second processing vessel of the plasma apparatus using a plasma or gases ₂ O O ₂ gas and fluorine-containing gas in the Plasma is a process to suppress corrosion after treatment. [0011] A second aspect of the present invention is to provide a plasma etching system including a semiconductor film made of an oxide semiconductor, and a stacked lower Ti film, an Al film, and an upper Ti film formed thereon. The substrate of the formed Ti / Al / Ti laminated film is subjected to plasma etching of the Ti / Al / Ti laminated film. The plasma etching system is characterized by having a first etching device having a substrate for accommodating the substrate. In the processing container, in the processing container, a first plasma etching is performed on the upper Ti film and the Al film of the Ti / Al / Ti laminated film using a chlorine-containing gas; the second plasma etching device has a storage space. After the first plasma etching, the processing container of the substrate is subjected to a second plasma etching of the lower Ti film of the Ti / Al / Ti laminated film using a fluorine-containing gas, and the second plasma etching is performed at the same time. after the substrate, the use of O ₂ gas plasma, and O ₂ gas or a fluorine-containing plasma gases; and a vacuum transfer chamber, which is the above plasma etching apparatus of the first and the second plasma etching apparatus are connected Is maintained in the middle of the vacuum while being set in the middle Conveyance means in holding state is maintained under a vacuum, between the first and the second plasma etching apparatus 2 plasma etching apparatus, conveyance of the substrate. [0012] In the first and second aspects, a Cl ₂ gas may be used as the chlorine-containing gas. Further, CF ₄ gas can be used as the fluorine-containing gas. [0013] The first plasma etching apparatus may have a configuration in which the substrate is placed above a substrate mounting table in a processing container, and plasma etching is performed while a sacrificial material made of aluminum is arranged around the substrate. [0014] The first plasma etching apparatus and the second plasma etching apparatus may be configured to perform plasma etching using an inductively coupled plasma. [0015] In the plasma etching system according to the second aspect, a configuration in which three of the first plasma etching apparatuses and two of the second plasma etching apparatuses are connected to the vacuum transfer chamber is preferable. [Inventive Effect] [0016] According to the present invention, in the first plasma etching apparatus, since O ₂ gas or fluorine-containing gas is not used, the generation of AlOx or AlFx in the processing container can be suppressed, and In the second plasma etching apparatus, since there are no reaction by-products generated by etching containing Al, Al is only an adhered portion of the substrate, and therefore AlOx or AlFx in the chamber can be suppressed. Therefore, it is possible to significantly reduce particles generated in the processing container. [0017] Furthermore, in the first plasma etching apparatus, only the upper Ti film and the Al film of the Ti / Al / Ti laminated film are etched to leave the lower Ti film, so a semiconductor film made of an oxide semiconductor It will not be etched directly by the chlorine-containing gas. Furthermore, since the underlying Ti film is etched by the fluorine-containing gas by the second plasma etching device, the oxide semiconductor is resistant to the fluorine-containing gas, so even in the second plasma In the etching apparatus, etching of a semiconductor film made of an oxide semiconductor is suppressed. Therefore, the amount of cutting of a semiconductor film made of an oxide semiconductor can be reduced.

[0019] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. [0020] (Plasma Etching System) First, a plasma etching system to which one embodiment of the present invention is applied will be described. FIG. 1 is a schematic plan view showing a plasma etching system for implementing a plasma etching method related to an embodiment of the present invention. [0021] As shown in FIG. 1, the plasma etching system 100 is a multi-chamber type and includes a vacuum transfer chamber 10, a load lock chamber 20, three first plasma etching apparatuses 30, and two second plasma etching apparatuses. 40. The first plasma etching apparatus 30 and the second plasma etching apparatus 40 are processed under a specific reduced pressure atmosphere. The plan view of the vacuum transfer chamber 10 is hexagonal, and the load lock chamber 20, three first plasma etching apparatuses 30, and two second plasma etching apparatuses 40 are connected to each wall portion of the vacuum transfer chamber 10 via a gate valve G. A carrier 50 for accommodating a rectangular substrate S is arranged outside the load lock chamber 20. [0022] Between the two carriers 50, a conveying mechanism 60 is provided. The conveying mechanism 60 has a picker 61 (only one is shown in the figure) provided in two stages, and can be integrated with the two. Retreat and rotate the base 62. [0023] The vacuum transfer chamber 10 can be maintained in a specific reduced-pressure atmosphere, and a vacuum transfer mechanism 70 is provided in the middle. Then, the substrate S is transferred between the load lock chamber 20, the three first plasma etching processing devices 30, and the second plasma etching device 40 by the vacuum transfer mechanism 70. The vacuum transfer mechanism 70 is provided on a base 71 capable of rotating and moving up and down, and two substrate transfer arms 72 (only one shown in the figure) are provided so as to be able to move back and forth. [0024] The load lock chamber 20 is used for receiving the substrate S between the carrier 50 in the atmospheric atmosphere and the vacuum transfer chamber 10 in the reduced pressure atmosphere, and can switch the vacuum atmosphere and the atmospheric atmosphere in a short time. The loading lock chamber 20 is a substrate storage section provided in two upper and lower stages. In each substrate storage section, the substrate S is aligned by a positioner (not shown). [0025] The plasma etching system 100 further includes a control unit 80. The control unit 80 is constituted by a computer including a CPU and a memory unit, and each component of the plasma etching system 100 (the vacuum transfer chamber 10, the load lock chamber 20, the first plasma etching apparatus 30, and the second plasma etching apparatus 40 Each component of the conveying mechanism 60 and the vacuum conveying mechanism 70) is controlled to perform a specific process based on a processing recipe (program) stored in the memory unit. The processing recipe is stored in a storage medium such as a hard disk, an optical disk, or a semiconductor memory. [0026] (First Plasma Etching Apparatus) Next, the first plasma etching apparatus 30 will be described in detail. FIG. 2 is a cross-sectional view showing a first plasma etching apparatus 30. As described later, the first plasma etching apparatus 30 is used to etch an Al film up to the Ti / Al / Ti laminated film of the substrate S. For example, the first plasma etching device 30 has a rectangular tube shape made of aluminum with an inner wall surface anodized. Of the airtight body container 101. The main body container 101 is assembled to be disassembled and grounded. The main body container 101 is partitioned up and down by a dielectric wall 102, the upper side becomes an antenna container 103 that partitions an antenna chamber, and the lower side becomes a chamber (processing container) 104 that partitions a processing chamber. The dielectric wall 102 constitutes the top wall of the chamber 104 and is composed of ceramics such as Al ₂ O ₃ , quartz, and the like. [0027] Between the side wall 103a of the antenna container 103 and the side wall 104a of the cavity 104 in the body container 101, a support frame 105 protruding from the inside is provided, and a dielectric wall 102 is placed on the support frame 105. [0028] A shower frame 111 for supplying a processing gas is embedded in a lower portion of the dielectric wall 102. The shower housing 111 is in a state of being suspended from the ceiling of the main body container 101 by a plurality of hangers (not shown). [0029] The shower frame 111 is made of a conductive material, such as aluminum whose inner surface or outer surface is anodized. A horizontally extending gas flow path 112 is formed in the shower frame 111, and a plurality of gas discharge holes 112a extending downward are continuously formed in the gas flow path 112. [0030] In the center of the upper surface of the dielectric wall 102, a gas supply pipe 121 is provided so as to communicate with the gas flow path 112. The gas supply pipe 121 penetrates from the ceiling of the main body container 101 to the outside thereof, and branches into branch pipes 121a and 121b. The branch pipe 121 a is connected to a chlorine-containing gas supply source 122 that supplies a chlorine-containing gas, for example, a chlorine gas (Cl ₂ gas). Further, the supply branch pipe 121b connected to the use of Ar gas as a flushing gas or a dilution gas, an inert gas supply source of an inert gas like N ₂ gas 123. Chlorine-containing gas is used as an etching gas and a dry cleaning gas. A flow controller or a valve system such as a mass flow controller is provided in the branch pipes 121a and 121b. [0031] The gas supply pipe 121, the branch pipes 121a, 121b, the chlorine-containing gas supply source 122, the inert gas supply source 123, the flow controller, and the valve system constitute a processing gas supply mechanism 120. [0032] In the first plasma etching apparatus 30, the chlorine-containing gas supplied from the processing gas supply mechanism 120 is supplied into the shower frame 111, and is discharged into the chamber 104 from the gas discharge hole 112a below it. The etching of the Ti / Al / Ti laminated film of the substrate S is performed. The chlorine-containing gas is preferably a Cl ₂ gas, but a boron trichloride (BCl ₃ ) gas, a carbon tetrachloride (CCl ₄ ) gas, or the like can also be used. [0033] A high-frequency (RF) antenna 113 is disposed in the antenna container 103. The high-frequency antenna 113 is configured by arranging an antenna 113a made of a highly conductive metal such as copper or aluminum into any shape conventionally used, such as a loop or a spiral shape. Even a multiple antenna having a plurality of antenna sections may be used. The high-frequency antenna 113 is separated from the dielectric wall 102 by a spacer 117 made of an insulating member. [0034] A terminal 118 of the antenna 113a is connected to a power feeding member 116 extending above the antenna container 103. A power supply line 119 is connected to the upper end of the power supply member 116, and a matcher 114 and a high-frequency power source 115 are connected to the power supply line 119. Further, by supplying high-frequency power of a frequency of, for example, 13.56 MHz, to the high-frequency antenna 113 from the high-frequency power source 115, an induced electric field is formed in the chamber 104, and the processing gas supplied from the shower frame 111 is formed by the induced electric field. Is plasmatized to generate an inductively coupled plasma. [0035] A substrate mounting table 130 on which a substrate G is placed is provided on the bottom wall in the chamber 104 via a spacer 126 made of insulating material constituting a frame edge. The substrate mounting table 130 includes a base material 131 provided on the spacer 126 described above, an electrostatic jig 132 provided on the base material 131, and a shielding ring made of an insulator covering the sidewall of the base material 131 and the electrostatic jig 132. 133. The base material 131 and the electrostatic jig 132 have a rectangular shape corresponding to the shape of the substrate S, and the entire substrate mounting table 130 has a rectangular plate shape or a column shape. The spacer 126 and the side wall insulating member 133 are made of an insulating ceramic such as alumina. [0036] The electrostatic fixture 132 includes a dielectric layer 145 made of a ceramic magnetic spray film formed on the surface of the substrate 131, and an adsorption electrode 146 provided inside the dielectric layer 145. The adsorption electrode 146 can have various shapes such as a plate shape, a film shape, a lattice shape, and a mesh shape. A DC power source 148 is connected to the adsorption electrode 146 via a power supply line 147, and a DC voltage is applied to the adsorption electrode 146. The power to the suction electrode 146 is turned on and off by a switch (not shown). By applying a DC voltage to the adsorption electrode 146, an electrostatic adsorption force such as a Coulomb force or a strong Rabeck force is generated, and the substrate S is adsorbed. As the dielectric layer 145 of the electrostatic jig 132, aluminum oxide (Al ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), or the like can be used. [0037] A high-frequency power source 153 for applying a bias voltage is connected to the base material 131 via a power supply line 151. Furthermore, a matcher 152 is provided between the base material 131 of the power supply line 151 and the high-frequency power source 153. The high-frequency power source 153 is used to pull ions into the substrate S on the substrate 131, and uses a frequency in a range of 50 kHz to 10 MHz, for example, 3.2 MHz. [0038] In the substrate 131 of the substrate mounting table 130, a temperature adjustment mechanism and a temperature sensor (not shown) are provided for controlling the temperature of the substrate S. Furthermore, in a state where the substrate S is placed on the substrate placing table 130, a heat conducting gas for heat transfer between the substrate S and the substrate placing table 130, such as a heat conducting gas supply mechanism (not shown) for supplying He gas, is provided. In addition, a plurality of lift pins (not shown) for receiving and receiving the substrate S are provided on the substrate mounting table 130 so as to be able to sag the upper surface of the electrostatic jig 132. The lifting pin is in a state where the upper surface of the jig 132 projects upward. [0039] The side wall 104a of the chamber is provided with a loading / unloading port 155 for loading and unloading the substrate S into / from the chamber 104, and the loading / unloading port 155 is opened and closed by the gate valve G. By opening the gate valve G, the board | substrate S can be carried in and out via the carrying in / out port 155 in accordance with the vacuum carrying mechanism 70 provided in the vacuum carrying chamber 10. [0040] A plurality of exhaust ports 159 (only two shown in the figure) are formed at edges or corners of the bottom wall of the chamber 104, and each exhaust port 159 is provided with an exhaust mechanism 160. The exhaust mechanism 160 includes an exhaust pipe 161 connected to the exhaust port 159, an automatic pressure control valve (APC) 162 for controlling the pressure in the chamber 104 by adjusting the opening degree of the exhaust pipe 161, and A vacuum pump 163 for exhausting the inside of the chamber 104 through the exhaust pipe 161. Then, the inside of the chamber 104 is evacuated by the vacuum pump 163, and the opening degree of the automatic pressure control valve (APC) 162 is adjusted during the plasma etching process to set and maintain the inside of the chamber 104 at a specific vacuum atmosphere. [Second Plasma Etching Apparatus] Next, the second plasma etching apparatus 40 will be described in detail. FIG. 3 is a cross-sectional view showing a second plasma etching apparatus 40. The second plasma etching apparatus 40 is used for etching the Ti film under the Ti / Al / Ti laminated film of the substrate S as described later, and for post-corrosion suppression treatment. The second plasma etching apparatus 40 has the same configuration as the first plasma etching apparatus 30 of FIG. 2 except that a processing gas supply mechanism 220 is provided instead of the processing gas supply mechanism 120. Therefore, the same reference numerals are given to those that are the same as those in FIG. 2, and descriptions thereof are omitted. [0042] The processing gas supply mechanism 220 includes a gas supply pipe 221, branch pipes 121a, 221b, and 221c branched from the gas supply pipe 221 above and outside the main body container 101, and a source of O ₂ gas that is connected to the branch pipe 221a. An O ₂ gas supply source 222, and a fluorine-containing gas supply source 223 such as carbon tetrafluoride gas (CF ₄ gas) connected to the branch pipe 221b, and a supply connected to the branch pipe 221c as a flush. An inert gas supply source 224 of an inert gas, such as an Ar gas or a diluent gas, or an N ₂ gas. The gas supply pipe 221 is the same as the gas supply pipe 121 of the first plasma etching apparatus 30 in FIG. 2, and is connected to the gas flow path 112 of the shower frame 111. [0043] In the second plasma etching apparatus 40, the fluorine-containing gas supplied from the processing gas supply mechanism 220 is supplied into the shower frame 111, and is discharged into the chamber 104 from the gas discharge hole 112a below it. The etching of the Ti film under the Ti / Al / Ti laminated film of the substrate S is performed. Furthermore, after the etching, the O ₂ gas, O ₂ gas, and fluorine-containing gas supplied from the processing gas supply mechanism 220 is also discharged into the chamber 104, and a post-treatment for suppressing corrosion is performed. As the fluorine-containing gas, although CF ₄ gas is preferred, sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ ), or the like may be used. [0044] (Plasma Etching Method) Next, for the plasma etching method related to one implementation type of the invention implemented by the above plasma etching system 100, refer to the flowchart of FIG. 4 and the engineering cross-sectional view of FIG. 5. Explain. [0045] Here, as shown in FIG. 5 (a), a substrate S having a Ti / Al / Ti laminated film as a film to be etched is first prepared (step 1). The substrate S is a TFT having a bottom gate structure of a channel etching type. Specifically, a gate electrode 2 is formed on a glass substrate 1, and a semiconductor film 4 made of an oxide semiconductor such as IGZO is formed thereon via a gate insulating film 3, and a source electrode and Ti / Al / Ti laminated film 5 of a drain electrode. The Ti / Al / Ti laminated film 5 includes an upper Ti film 5a, a lower Ti film 5c, and an Al film 5b interposed therebetween. The Al film 5b may be an Al alone or an Al alloy such as Al-Si. The film thickness of the upper Ti film 5a and the lower Ti film 5c is approximately 30 to 100 nm, and the film thickness of the Al film 5b is approximately 300 to 1000 nm. A photoresist layer 6 is formed on the Ti / Al / Ti laminated film 5 as an etching mask. The substrate S is stored in a carrier 50. [0046] The above-mentioned substrate S is taken out from the carrier 50 by the conveyance mechanism 60 and conveyed to the load lock chamber 20, and the vacuum conveyance mechanism 70 in the vacuum conveyance chamber 10 receives the substrate S from the load lock chamber 20 and conveys it to the first electrical In the first plasma etching apparatus 30, plasma etching is performed on the Ti film 5a and the A1 film 5b on the Ti / Al / Ti laminated film 5 using a chlorine-containing gas such as Cl ₂ gas (step 2, Figure 5 (b)). [0047] The plasma etching in step 2 will be specifically described below. In the first plasma etching apparatus 30, first, the inside of the chamber 104 is adjusted to a pressure suitable for the vacuum transfer chamber 10 by the exhaust mechanism 160, and the gate valve G is opened to carry the substrate S from the transfer port 155 to the vacuum transfer mechanism. 70 is carried into the chamber 104, and the substrate S is placed on the substrate mounting table 130. After the vacuum conveyance mechanism 70 is retracted from the chamber 104, the gate valve G is closed. [0048] In this state, the pressure in the chamber 104 is adjusted to a specific degree of vacuum by an automatic pressure control valve (APC) 162, and at the same time, the processing gas supply mechanism 120 passes through the shower frame 111 to serve as the processing gas. The etching gas, that is, a chlorine-containing gas, such as a Cl ₂ gas, is supplied into the chamber 104. In addition to the chlorine-containing gas, an inert gas such as an Ar gas may be supplied as a diluent gas. [0049] At this time, the substrate S is attracted by the electrostatic jig 132, and the temperature is adjusted by a temperature adjustment mechanism (not shown). [0050] Next, a high frequency of 13.56 MHz is applied to the high frequency antenna 113 from the high frequency power source 115, thereby forming a uniform induced electric field in the processing chamber 104 via the dielectric wall 102. By the induced electric field thus formed, a plasma containing chlorine gas is generated. With the high-density inductive coupling plasma thus generated, the upper Ti film 5a and the Al film 5b of the Ti / Al / Ti laminated film 5 of the substrate S are etched. [0051] In a specific method, the etching is terminated at the point when the end point of the etching is detected. [0052] After the etching in step 2 is completed, the substrate S is taken out from the first plasma etching apparatus 30 by the vacuum conveying mechanism 70, and is transferred to the second plasma etching apparatus 40. In the second plasma etching apparatus 40, Plasma etching is performed on the underlying Ti film 5c of the Ti / Al / Ti laminated film 5 using a fluorine-containing gas such as CF ₄ gas (step 3, FIG. 5 (c)). [0053] Hereinafter, the plasma etching in step 3 will be specifically described. In the second plasma etching apparatus 40, first, the inside of the chamber 104 is adjusted to a pressure suitable for the vacuum transfer chamber 10 by the exhaust mechanism 160, and the gate valve G is opened to carry the substrate S from the transfer port 155 to the vacuum transfer mechanism. 70 is carried into the chamber 104, and the substrate S is placed on the substrate mounting table 130. After the vacuum conveyance mechanism 70 is retracted from the chamber 104, the gate valve G is closed. [0054] In this state, the pressure in the chamber 104 is adjusted to a specific vacuum degree by an automatic pressure control valve (APC) 162, and at the same time, the processing gas is supplied from the processing gas supply mechanism 220 through the shower frame 111 as the processing gas. An etching gas, that is, a fluorine-containing gas, such as a CF ₄ gas, is supplied into the chamber 104. In addition to the fluorine-containing gas, an inert gas such as an Ar gas may be supplied as a diluent gas. [0055] At this time, the substrate S is attracted by the electrostatic fixture 132, and the temperature is adjusted by a temperature adjustment mechanism (not shown). [0056] Next, a high frequency, such as 13.56 MHz, is applied to the high frequency antenna 113 from the high frequency power source 115, thereby forming a uniform induced electric field in the cavity 104 via the dielectric wall 102. By the induced electric field thus formed, a plasma containing fluorine gas is generated. With the high-density inductive coupling plasma thus generated, the lower Ti film 5c in the Ti / Al / Ti laminated film 5 of the substrate S is etched. [0057] In a specific method, the etching is terminated at the point when the end point of the etching is detected. [0058] After the etching in step 3 is completed, the substrate mounting table 130 maintained in the chamber 104 of the second plasma etching apparatus 40 holds the substrate S, and O is supplied to the chamber 104 as a processing gas. ₂ gas, or O ₂ gas and fluorine-containing gas (for example, CF ₄ gas), and perform post-treatment to suppress corrosion (step 4, FIG. 5 (d)). [0059] Hereinafter, the processing after step 4 will be specifically described. After the plasma etching in step 3 of the second plasma etching apparatus 40, the inside of the chamber 104 is vacuum-evacuated by the exhaust mechanism 160. In this case, the chamber may be flushed by supplying an inert gas such as an Ar gas from the inert gas supply source 224 as required. After that, the pressure in the chamber 104 is adjusted to a specific vacuum degree, and at the same time, O ₂ gas or O ₂ gas and a fluorine-containing gas (such as CF) are supplied into the chamber 104 from the processing gas supply mechanism 220 through the shower frame 111. ₄ gas), as a post-treatment gas. Other than these, an inert gas such as Ar may be supplied as a diluent gas. [0060] Furthermore, high-frequency power is applied from the high-frequency power source 115 to the high-frequency antenna 113 to form an induced electric field in the chamber 104 to generate O ₂ gas or a plasma of O ₂ gas and fluorine-containing gas. The generated inductively coupled plasma is subjected to post-etching treatment to suppress corrosion after being etched by the plasma. At this time, even if only O ₂ gas is used as the processing gas, it has a corrosive effect. In addition to applying a fluorine-containing gas such as CF ₄ gas to the O ₂ gas, the corrosive effect is further enhanced. In addition, as the fluorine-containing gas used in the post-treatment, although CF ₄ gas is preferred, sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ ), or the like may be used. The fluorine-containing gas used in etching the lower Ti film 5c is preferably the same as the fluorine-containing gas used in the post-processing. In this way, by setting the fluorine-containing gas on both sides to be the same, the gas supply mechanism can be simplified, and at the same time, it can be the same process as the one after etching and corrosion suppression, so the time after the corrosion suppression can be shortened. [0061] After the second plasma etching apparatus 40 is processed afterward, the substrate S is taken out from the chamber 104 of the second plasma etching apparatus 40 by the vacuum transfer mechanism 70, and is transferred to the load lock chamber 20, and the transfer mechanism 60 is used. Return to carrier 50. [0062] In the conventional plasma etching of a Ti / Al / Ti laminated film, three layers are etched together with a Cl-containing gas such as Cl ₂ gas in a chamber of a plasma etching device, and thereafter, the same a chamber, after the O ₂ gas by plasma or O ₂ gas and the fluorine-containing gas plasma treatment. [0063] In this case, Ti and Al constituting the Ti / Al / Ti laminated film are etched by Cl ₂ gas, and a gas-like TiClx gas (for example, TiCl ₄ gas) and an AlClx gas ( For example, AlCl ₃ ) is discharged from the chamber. Ti + Cl ₂ → TiClx ↑ Al + Cl ₂ → AlClx ↑ [0064] However, when the post-treatment for suppressing corrosion is performed, when O ₂ gas or CF ₄ gas is supplied, it reacts with the AlClx gas remaining in the chamber. And solid AlOx or AlFx is generated, which remains in the cavity and becomes fine particles, which has a bad effect on the product. [0065] Furthermore, when the Ti / Al / Ti laminated film is etched with a chlorine-containing gas such as Cl ₂ gas, the oxide semiconductor film on the substrate is etched at the time of over-etching, and the cutting amount of the oxide semiconductor film increases. . [0066] Thus, in the present embodiment, in the first plasma etching apparatus 30, the Ti / Al / Ti laminated film 5 is etched by a gas containing Cl, such as Cl ₂ gas, and the upper Ti film 5a and After the Al film 5b, in the second plasma etching apparatus 40, the Ti film 5c under the Ti / Al / Ti laminated film 5 is etched by a fluorine-containing gas such as CF ₄ gas, and then by the second plasma etching apparatus 40, it was based on the O ₂ gas plasma, the O ₂ gas or a fluorine-containing gas and the plasma treatment. [0067] In this way, in the first plasma etching apparatus 30, since O ₂ gas or fluorine-containing gas is not used, the generation of AlOx or AlFx in the processing container can be suppressed, and further, in the second plasma In the etching device 40, there are no reaction by-products caused by the etching containing Al in the chamber, and Al is only an adhesion portion of the substrate. Therefore, AlOx or AlFx in the chamber can be suppressed. Therefore, particles generated in the cavity can be significantly reduced. [0068] Furthermore, in the first plasma etching apparatus 30, only the upper Ti film 5a and the Al film 5b of the Ti / Al / Ti laminated film 5 are etched to leave the lower Ti film 5c. Therefore, an oxide semiconductor is used. The formed semiconductor film 4 is not directly etched by the chlorine-containing gas, and because the lower Ti film 5c is etched by the fluorine-containing gas by the second plasma etching device 40, the oxide semiconductor is resistant to the fluorine-containing gas. Therefore, even in the second plasma etching apparatus 40, the etching of the semiconductor film 4 made of an oxide semiconductor is suppressed. Therefore, the amount of cutting of the semiconductor film 4 made of an oxide semiconductor can be reduced. [0069] In the case of using both the O ₂ gas and the fluorine-containing gas having a high corrosion suppression effect in the second plasma etching apparatus 40, the fluorine-containing gas for etching the lower Ti film 5c is used. The same gas as the fluorine-containing gas used for the post-processing gas can simplify the gas supply mechanism of the second plasma etching apparatus 40 and can be the same process as the post-etching and corrosion suppression post-processing, so the time for post-corrosion suppression processing can be shortened. . [0070] In addition, since the two types of apparatuses of the first plasma etching apparatus 30 and the second plasma etching apparatus 40 are processed, the productivity may be reduced. However, the plasma etching system 100 is equipped with three units. The first plasma etching device 30 of step 2 with relatively long processing time is equipped with two second plasma etching devices 40 of steps 3 and 4 whose total processing time is shorter than that of step 2. The equipment is not too large and can be used. Maintain high productivity. That is, in the conventional system, although only three types of plasma etching devices having the same structure as the first plasma etching device 30 were provided, the first plasma of step 2 was carried out by mounting three of them. The etching apparatus 30 is equipped with two second plasma etching apparatuses 40 for performing steps 3 and 4, which can suppress the increase in equipment to a minimum and maintain the same high productivity as before. [Other Examples of the First Plasma Etching Apparatus] Next, other examples of the first plasma etching apparatus will be described. FIG. 6 is a partial cross-sectional view showing an important part of another example of the first plasma etching apparatus. Since the basic structure of the apparatus of FIG. 6 is the same as that of the plasma etching apparatus of FIG. 2, in FIG. 6, the same reference numerals are given to the same parts as those in FIG. 2 and the description is omitted. [0072] The Ti / Al / Ti laminated film used for the source electrode and the drain electrode of the TFT is formed with a thick Al film in the center. Therefore, the etching of the Ti / Al / Ti laminated film is performed by etching the Al film. main. When the Al film is etched with a chlorine-containing gas, such as a Cl ₂ gas, the etching rate on the periphery of the substrate tends to be high. That is, in the etching of a highly reactive film like an Al film, a peripheral portion of a substrate having a large amount of unreacted etching gas is present, and an etching rate at the peripheral portion of the substrate is increased by a load effect. Such unevenness of the etching rate is difficult to control under the plasma power or gas flow distribution. [0073] When the in-plane uniformity of the etching rate is poor, a long over-etching is required. Even when the lower Ti film is not etched as described above, the lower Ti film is etched at the outer periphery of the substrate, and the oxide A semiconductor film made of a semiconductor is damaged. [0074] In this example, as shown in FIG. 6, a sacrificial material 171 made of Al is disposed on the frame-shaped shielding ring 133 provided on the outer periphery of the substrate S so as to surround the outer periphery of the substrate S. [0075] By disposing the sacrificial material 171 made of Al on the periphery of the substrate S in this manner, the sacrificial material 171 can consume the remaining chlorine-containing gas on the periphery of the substrate, which can suppress the load effect and suppress the etching rate on the periphery of the substrate. Accordingly, the in-plane etching uniformity can be improved, the time for over-etching can be shortened, and damage to a semiconductor film made of an oxide semiconductor can be further reduced. [0076] The etching rate of the Ti / Al / Ti laminated film is compared between the case where the sacrificial material made of Al is actually used and the case where it is not used. For the case of using a sacrificial material made of Al, as shown in FIG. 7, a substrate on which a Ti / Al / Ti laminated film is formed is placed on the corner of plain glass, and a frame-shaped Al is placed on the shielding ring 3 mm away from the substrate. The sacrificial material is made and etched. Even in a case where Al absorption is not used, a substrate on which a Ti / Al / Ti laminated film is formed is placed on the corner of plain glass and etched. After the etching, the etching rate of the Ti / Al / Ti laminated film was measured at a plurality of points along the diagonal from the corner of the substrate for the case where the sacrificial material made of Al was used and the case where it was not used. [0077] The results are shown in FIG. 8. 8 is a graph showing a relationship between a distance from a corner portion of a substrate and an etching rate of a Ti / Al / Ti multilayer film. As shown in the figure, when using a sacrificial material made of Al, it was confirmed that the etching rate (about 500 nm / min) at the edge portion of the substrate and the value (about 350 nm / min) where the etching is the smallest 50 mm away from the corner portion The difference is about 150 nm / min. For this reason, when the sacrificial material made of Al is not used, the etching rate (about 1000 nm / min) at the edge of the substrate and the value at which the etching rate becomes the smallest 50 mm from the corner ( A difference of about 500 nm / min) is about 500 nm / min. By using a sacrificial material made of Al, the etching rate at the edge of the substrate can be suppressed. [Other Applications] In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the idea of the present invention. Moreover, in the above-mentioned embodiment, although an example of using an inductively coupled plasma etching apparatus as the plasma etching apparatus is shown, it is not limited to this, and even a capacitive coupling plasma etching apparatus or a microwave plasma etching apparatus is used. Other plasma etching devices are also possible. [0079] Furthermore, in the above-mentioned embodiment, an example in which three first plasma etching devices and two second plasma etching devices are installed in the plasma etching system is shown, but the number is not limited. Here, it is sufficient to make the appropriate number according to the required productivity.

[0080]

1‧‧‧ glass substrate

2‧‧‧Gate electrode

3‧‧‧Gate insulation film

4‧‧‧ semiconductor film

5‧‧‧Ti / Al / Ti laminated film

5a‧‧‧upper Ti film

5b‧‧‧Al film

5c‧‧‧ underlying Ti film

6‧‧‧ photoresist layer

10‧‧‧Vacuum Handling Room

20‧‧‧Load lock room

30‧‧‧The first plasma etching device

40‧‧‧Second plasma etching device

50‧‧‧ carrier

60‧‧‧Transportation agency

70‧‧‧vacuum handling mechanism

80‧‧‧Control Department

100‧‧‧ Plasma Etching System

101‧‧‧handling container

102‧‧‧ Dielectric Wall

104‧‧‧ Chamber

111‧‧‧ spray frame

113‧‧‧HF Antenna

115‧‧‧High-frequency power

120, 220‧‧‧Processing gas supply mechanism

130‧‧‧ substrate mounting table

132‧‧‧ static clamp

133‧‧‧shield ring

160‧‧‧Exhaust mechanism

171‧‧‧ sacrificial material

S‧‧‧ substrate

[0018] FIG. 1 is a schematic plan view showing a plasma etching system for implementing a plasma etching method related to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a first plasma etching apparatus mounted in FIG. 1. FIG. 3 is a cross-sectional view showing a second plasma etching apparatus mounted on the system of FIG. 1. FIG. 4 is a flowchart showing a plasma etching method related to one embodiment of the invention in which the plasma etching system in FIG. 1 is implemented. FIG. 5 is an engineering cross-sectional view showing a plasma etching method related to one embodiment of the invention in which the plasma etching system in FIG. 1 is implemented. FIG. 6 is a partial cross-sectional view showing an important part of another example of the plasma etching apparatus. Fig. 7 is a diagram for explaining an experiment for confirming the effect of the sacrificial material made of Al in another example of the plasma etching apparatus. FIG. 8 is a diagram showing the effect of the sacrificial material made of Al.

Claims (11)

A plasma etching method is a Ti / Al / Ti stack composed of a semiconductor film composed of an oxide semiconductor, and a lower Ti film, an Al film, and an upper Ti film laminated on the semiconductor film. The substrate of the film is subjected to plasma etching of the above-mentioned Ti / Al / Ti laminated film. The plasma etching method is characterized in that: the substrate is carried into a processing container of a first plasma etching device, and the above-mentioned is performed using a chlorine-containing gas. The first plasma etching process of the above Ti film and the Al film of the Ti / Al / Ti laminated film; Next, the substrate after the first plasma etching is transferred to a processing container of a second plasma etching apparatus A second plasma etching process for the lower Ti film of the Ti / Al / Ti laminated film using a fluorine-containing gas; and maintaining the substrate after the second plasma etching is maintained at the second plasma a state within the processing vessel of the apparatus, the plasma using an O ₂ gas or O ₂ gas and a fluorine-containing plasma gases, after engineering process for inhibiting corrosion. The plasma etching method according to claim 1, wherein the chlorine-containing gas is a Cl ₂ gas. The plasma etching method according to claim 1 or 2, wherein the fluorine-containing gas is a CF ₄ gas. The plasma etching method according to claim 1 or 2, wherein the first plasma etching apparatus is configured to place the substrate on a substrate mounting table in a processing container, and arrange a sacrificial material made of aluminum around the substrate. For plasma etching. The plasma etching method according to claim 1 or 2, wherein the first plasma etching apparatus and the second plasma etching apparatus perform plasma etching by inductive coupling. A plasma etching system is a Ti / Al / Ti stack composed of a semiconductor film composed of an oxide semiconductor, and a lower Ti film, an Al film, and an upper Ti film laminated on the semiconductor film. The substrate of the film is subjected to plasma etching of the Ti / Al / Ti laminated film. The plasma etching system is characterized by having a first etching device having a processing container for storing the substrate, and used in the processing container. A chlorine-containing gas performs a first plasma etching on the upper Ti film and the Al film of the Ti / Al / Ti laminated film; a second plasma etching device includes a processing container that houses the substrate, and After the plasma etching, the lower Ti film of the Ti / Al / Ti laminated film was subjected to a second plasma etching using a fluorine-containing gas, and the substrate after the second plasma etching was subjected to an electric operation using O ₂ gas. Plasma, or plasma of O ₂ gas and fluorine-containing gas; and a vacuum transfer chamber, where the first plasma etching device and the second plasma etching device are connected, and a vacuum is maintained in the middle thereof, while the The transport mechanism installed in the middle is maintained In a vacuum state, the substrate is transferred between the first plasma etching apparatus and the second plasma etching apparatus. The plasma etching system according to claim 6, wherein the chlorine-containing gas is Cl ₂ gas. The plasma etching system according to claim 6 or 7, wherein the fluorine-containing gas is a CF ₄ gas. The plasma etching system according to claim 6 or 7, wherein: the first plasma etching apparatus includes a substrate mounting table on which the substrate is placed in the processing container, and 牺牲 a sacrificial material made of aluminum disposed around the substrate. The plasma etching system according to claim 6 or 7, wherein the first plasma etching apparatus and the second plasma etching apparatus have a plasma generating mechanism for generating an inductively coupled plasma. The plasma etching system according to claim 6 or 7, wherein the vacuum transfer chamber is connected to three of the first plasma etching apparatuses and two of the second plasma etching apparatuses are connected.