TW201909273A - Etching method and etching device - Google Patents

Abstract

It can improve the quality of flat panel display (FPD). An etching method comprises a loading step of loading a substrate to be processed into a chamber, wherein a plurality of elements are formed on the substrate, and the electrode layer is formed on the semiconductor layer and comprises a first Ti film, an Al film and a second Ti film; a supplying step of supplying the first process gas into the chamber; a first etching step of etching the second Ti film included in the electrode layer of each element by a plasma of the first process gas, and etching the Al film included in the electrode layer of each element until the first Ti film is exposed in any element; a switching step of switching the process gas to be supplied into the chamber from the first process gas to the second process gas containing N2 gas; and a second etching step of resuming etching the electrode layer of each element by a plasma of the second process gas.

Description

Etching method and etching device

Various aspects and embodiments of the present invention relate to an etching method and an etching apparatus.

Thin film transistors (TFT: Thin Film Transistor) used in FPD (Flat Panel Display) are patterned on a glass substrate, such as a gate electrode, a gate insulating film, a semiconductor layer, and the like. Formed by sequential stratification. From the viewpoint of high electron mobility and low power consumption, an oxide semiconductor composed of indium (In), gallium (Ga), and zinc (Zn) is used in the channel of the TFT. Such an oxide semiconductor has a relatively high electron mobility even in an amorphous state. Therefore, by using an oxide semiconductor in the channel of the TFT, a high-speed switching operation can be realized.

For example, in a gate-etched TFT with a bottom gate structure, a gate electrode, a gate insulating film, and an oxide semiconductor film are sequentially formed on a glass substrate, and then an electrode film is formed on the oxide semiconductor film. The metal film is etched with a plasma or the like, thereby forming a source electrode and a drain electrode. As the electrode film forming the source electrode and the drain electrode, for example, a metal film in which a titanium (Ti) film, an aluminum (Al) film, and a Ti film are laminated is often used. As an etching gas in this case, chlorine-containing gas is used A gas such as Cl ₂ gas. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-235968

[Problems to be Solved by the Invention]

However, in the FPD, it is required to accurately process a plurality of TFTs included in the FPD in order to suppress variations in image quality. However, in recent years, the FPD tends to become larger. Therefore, in the FPD manufacturing process, it becomes difficult to uniformly process a plurality of TFTs arranged on a large glass substrate.

For example, depending on the distribution of the plasma on the glass substrate, there may be cases where the etching rate of the electrode film varies depending on each part. Therefore, in a TFT located at a low etching rate, when the etching is continued until the electrode film is etched surely, the TFT located at a high etching rate is etched to the oxide below the electrode film. Semiconductor layer. As a result, the thickness of the oxide semiconductor of each TFT varies, and the quality of the FPD is deteriorated.

Further, in a TFT located at a low etching rate, when the etching by plasma is continued until the electrode film is reliably etched, the oxide semiconductor layer of the TFT located at a high etching rate is exposed for a long time. In plasma. Thereby, the characteristics of the oxide semiconductor layer may be changed. This causes variations in the characteristics of the oxide semiconductor of each TFT, resulting in deterioration of the quality of the FPD. [Means to solve the problem]

One aspect of the present invention is an etching method, which is characterized in that it includes: a moving-in process; a supply process; a first etching process; a switching process; and a second etching process. In the moving-in process, a processed substrate provided with a plurality of elements "forming an electrode layer on a semiconductor layer" is moved into the chamber. The electrode layer is an Al film laminated on the first Ti film, and the first layer is laminated on the Al film. 2Ti film. In the supply process, the first processing gas is supplied into the chamber. In the first etching process, the second Ti film contained in the electrode layer of each element is etched by the plasma of the first processing gas in the chamber, and the Al contained in the electrode layer of each element is etched in any element. Until the first Ti film is exposed. In the switching process, the processing gas supplied into the chamber is switched from the first processing gas to the second processing gas containing N ₂ gas. In the second etching process, the electrode layer of each element is etched again in the chamber by the plasma of the second processing gas. [Effect of the invention]

According to various aspects and embodiments of the present invention, the quality of FPD can be improved.

The etching method disclosed in this case is based on an embodiment and includes: a moving-in process; a supply process; a first etching process; a first switching process; and a second etching process. In the moving-in process, a processed substrate provided with a plurality of elements "forming an electrode layer on a semiconductor layer" is moved into the chamber. The electrode layer is an Al film laminated on the first Ti film, and the first layer is laminated on the Al film. 2Ti film. In the supply process, the first processing gas is supplied into the chamber. In the first etching process, the second Ti film contained in the electrode layer of each element is etched by the plasma of the first processing gas in the chamber, and the Al contained in the electrode layer of each element is etched in any element. Until the first Ti film is exposed. In the first switching process, the processing gas supplied into the chamber is switched from the first processing gas to a second processing gas containing N ₂ gas. In the second etching process, the electrode layer of each element is etched again in the chamber by the plasma of the second processing gas.

In addition, the etching method disclosed in this case is based on an embodiment, and may further include: a first determination process for measuring the light emission intensity of light corresponding to the wavelength of the Ti element in the space existing in the chamber during the first etching process, And it is judged whether the luminous intensity turns to increase after decreasing. In the first switching process, it is also possible to use the first judgment process. When the luminous intensity of light determined to be corresponding to the wavelength of the Ti element decreases and increases, the processing gas supplied to the chamber is changed from the first The processing gas is switched to the second processing gas.

Moreover, in one embodiment of the etching method disclosed in the present application, the first processing gas may be a mixed gas of BCl ₃ gas and Cl ₂ gas or may be Cl ₂ gas, and the second processing gas may be A mixed gas of Cl ₂ gas and N ₂ gas.

In addition, the etching method disclosed in this case is based on one embodiment, and further includes: a second switching process; and a third etching process. In the second switching process, in the second etching process, after the first Ti film of all the elements is exposed, the processing gas supplied into the chamber is switched from the second processing gas to a third processing gas that does not include a nitrogen element. In the third etching process, the etching of the electrode layer of each element is started again in the chamber with the plasma of the third processing gas.

In addition, the etching method disclosed in this case is based on one embodiment, and may further include a second determination process for measuring the light emission intensity of light having a wavelength corresponding to the Ti element in the space existing in the chamber during the second etching process. It is determined whether the increase rate of the luminous intensity is equal to or less than a predetermined value. In the second switching process, it is also possible to perform the second determination process. When the increase rate of the luminous intensity of light corresponding to the wavelength of the Ti element is determined to be less than a predetermined value, the processing gas to be supplied into the chamber is removed from The second processing gas is switched to the third processing gas.

Furthermore, in one embodiment of the etching method disclosed in the present application, the third processing gas may be a mixed gas of BCl ₃ gas and Cl ₂ gas, or may be Cl ₂ gas.

Moreover, in one embodiment of the etching method disclosed in this application, the semiconductor layer may be an oxide semiconductor.

Moreover, in one embodiment of the etching method disclosed in this application, the oxide semiconductor may also constitute a channel of a TFT (Thin Film Transistor).

The etching apparatus disclosed in this case is based on one embodiment, and includes a chamber, a mounting table, a supply section, a generation section, and a control section. The mounting table is installed in the chamber, and a substrate to be processed on which a plurality of elements "forming an electrode layer on a semiconductor layer" are placed is placed. The electrode layer is formed by laminating an Al film on the first Ti film, A 2Ti film is laminated on it. The supply unit supplies the processing gas into the chamber. The generating unit generates a plasma of a processing gas to be supplied into a chamber in a state where a substrate to be processed is placed on a mounting table. The control unit executes: the first etching process; the switching process; and the second etching process. In the first etching process, the control unit controls the supply unit to supply the first processing gas into the chamber, and controls the generation unit to generate the plasma of the first processing gas in the chamber, thereby etching the electrode layer of each element. For the second Ti film contained, the Al film contained in the electrode layer of each element is etched in any element until the first Ti film is exposed. In the switching process, the control unit controls the supply unit to switch the processing gas supplied into the chamber from the first processing gas to the second processing gas containing N ₂ gas. In the second etching process, the control unit controls the generation unit to generate the plasma of the second processing gas in the chamber, thereby restarting the etching of the electrode layer of each element.

Hereinafter, embodiments of the etching method and the etching apparatus disclosed in this case will be described in detail with reference to the drawings. In addition, the etching method and the etching apparatus disclosed in the present application are not limited by the following embodiment.

[Configuration of Etching Apparatus 1] FIG. 1 is a diagram showing an example of the etching apparatus 1. The etching apparatus 1 includes a main body 10 and a control unit 20. The etching apparatus 1 is an apparatus for etching a metal film formed on a substrate W to be processed by plasma. In this embodiment, the substrate W to be processed is, for example, an FPD panel, and a plurality of TFTs are formed on the substrate W to be processed by the etching process by the etching apparatus 1. In the following, each TFT formed on the substrate to be processed W is referred to as an element D.

The main body 10 is, for example, an airtight chamber 101 having a rectangular tube shape, and is formed of anodized aluminum on an inner wall surface. The chamber 101 is grounded. The chamber 101 is divided into upper and lower sides by a dielectric wall 102. The upper side of the dielectric wall 102 becomes an antenna chamber 103 containing an antenna, and the lower side of the dielectric wall 102 becomes a processing chamber 104 for generating plasma. . The dielectric wall 102 is made of a ceramic such as Al ₂ O ₃ or quartz, and constitutes a ceiling wall of the processing chamber 104.

Between the side wall 103a of the antenna chamber 103 and the side wall 104a of the processing chamber 104 in the chamber 101, a support scaffold 105 and a dielectric wall 102 protruding from the inside are provided by the support scaffold 105 .

A shower head frame 111 for supplying a processing gas into the processing chamber 104 is embedded in a lower portion of the dielectric wall 102. The shower head frame 111 is in a state of being hung from the ceiling of the chamber 101 by a plurality of hangers (not shown), for example.

The shower head frame 111 is made of, for example, a conductive material such as anodized aluminum. A gas diffusion chamber 112 extending horizontally is formed inside the shower head housing 111, and a plurality of gas discharge holes 112a extending downward are communicated with the gas diffusion chamber 112.

A gas supply pipe 124 is provided at approximately the center of the upper surface of the dielectric wall 102 so as to communicate with the gas diffusion chamber 112. The gas supply pipe 124 penetrates from the ceiling of the chamber 101 to the outside of the chamber 101 and is connected to the gas supply mechanism 120.

The gas supply mechanism 120 includes a gas supply source 121a, a gas supply source 121b, an MFC (Mass Flow Controller) 122a, an MFC 122b, a valve 123a, and a valve 123b. The gas supply mechanism 120 is an example of a supply unit. The MFC 122a is, for example, connected to a gas supply source 121a that supplies a chlorine-containing gas such as Cl ₂ gas, and controls the flow rate of the gas supplied from the gas supply source 121a. The valve 123a controls the supply and stop of the gas to the gas supply pipe 124, and the gas flow rate is controlled by the MFC 122a.

The MFC 122b is, for example, connected to a gas supply source 121b that supplies a nitrogen-containing gas such as N2 gas, and controls the flow rate of the gas supplied from the gas supply source 121b. The valve 123b controls the supply and stop of the gas to the gas supply pipe 124, and the flow rate of the gas is controlled by the MFC 122b.

The gas supplied from the gas supply mechanism 120 is supplied into the shower head frame 111 through the gas supply pipe 124 and diffuses into the gas diffusion chamber 112 of the shower head frame 111. The gas diffused in the gas diffusion chamber 112 is discharged from a gas discharge hole 112 a below the shower head frame 111 to a space in the processing chamber 104.

An antenna 113 is provided in the antenna chamber 103. The antenna 113 includes an antenna line 113a made of a highly conductive metal such as copper or aluminum. The antenna line 113a is formed in an arbitrary shape such as a loop or a spiral. The antenna 113 is spaced from the dielectric wall 102 by a spacer 117, and the spacer 117 is made of an insulating member.

The terminal 118 of the antenna line 113 a is connected to one end of a power feeding member 116 that extends upward from the antenna chamber 103. The other end of the power supply member 116 is connected to one end of a power supply line 119, and the other end of the power supply line 119 is connected to a high-frequency power source 115 via a matching device 114. The high-frequency power source 115 supplies high-frequency power having a frequency of, for example, 13.56 MHz to the antenna 113 via the matching unit 114, the power supply line 119, the power supply member 116, and the terminal 118. Thereby, an induction electric field is formed in the processing chamber 104 located below the antenna 113, and the gas supplied from the shower head frame 111 is plasmatized by the induced electric field, and an induction coupling plasma is generated in the processing chamber 104. . The shower head housing 111 and the antenna 113 are examples of a generating unit.

A bottom wall in the processing chamber 104 is provided with a mounting table 130 on which a substrate W to be processed is mounted via a spacer 126 formed in a frame shape by an insulating member. The mounting table 130 includes a substrate 131 provided on the spacer 126, an electrostatic fixture 132 provided on the substrate 131, and a protective member 133 formed of an insulating member and covering the substrate 131 and the electrostatic fixture. 132 sidewalls. The base material 131 and the electrostatic jig 132 have a rectangular shape corresponding to the shape of the substrate W to be processed, and the entire mounting table 130 is formed in a rectangular plate shape or a column shape. The spacer 126 and the protective member 133 are made of an insulating ceramic such as alumina.

The electrostatic jig 132 is provided on the upper surface of the base material 131. The electrostatic chuck 132 includes a dielectric layer 145 made of a ceramic diffusing film and an electrode 146 provided inside the dielectric layer 145. The electrode 146 can take various forms such as a plate shape, a film shape, a lattice shape, and a mesh shape. A DC power source 148 is connected to the electrode 146 via a power supply line 147, and a DC voltage supplied from the DC power source 148 is applied. The DC voltage applied from the DC power source 148 to the electrode 146 via the power supply line 147 is controlled by a switch (not shown). The DC voltage applied from the DC power source 148 generates an electrostatic adsorption force such as Coulomb's force or Johnson's Rabeck force on the electrode 146, and the substrate W to be processed placed on the electrostatic fixture 132 is held on the electrostatic fixture 132 by suction . As the dielectric layer 145 of the electrostatic jig 132, Al ₂ O ₃ or Y ₂ O ₃ can be used.

A matching device 152 and a high-frequency power source 153 are connected to the base material 131 via a power supply line 151. High-frequency power is supplied to the base material 131 through the power supply line 151 and the matcher 152, whereby ions are introduced into the substrate W to be processed disposed above the base material 131. The frequency of the high-frequency power supplied to the substrate 131 by the high-frequency power source 153 is, for example, a frequency in a range of 50 kHz to 10 MHz, for example, 3.2 MHz.

In addition, a temperature adjustment mechanism and a temperature sensor (both not shown) for controlling the temperature of the substrate W to be processed are provided in the base material 131 of the mounting table 130. In addition, the body 10 is provided with a heat transfer gas supply mechanism (not shown). This heat transfer gas supply mechanism is used to adjust the processed substrate in a state where the processed substrate W is placed on the mounting table 130. A heat transfer gas, such as He gas, for a heat transfer amount between the substrate W and the mounting table 130 is supplied between the substrate W to be processed and the mounting table 130. Furthermore, a plurality of lifting pins (not shown) are provided on the mounting table 130 so as to protrude and sink into the upper side of the electrostatic jig 132, and the plurality of lifting pins are used to collect the substrate W to be processed. Grant.

The side wall 104a of the processing chamber 104 is provided with a loading / unloading port 155 for loading and unloading the substrate W to be processed into and from the processing chamber 104. The loading / unloading port 155 is opened and closed by a gate valve G. By controlling the gate valve G to be in an open state, the substrate W to be processed can be carried in and out through the carrying in / out port 155.

The side wall 104a of the processing chamber 104 is provided with a window 106 formed of, for example, quartz or the like. Light emitted from ions or radicals in the plasma generated in the processing chamber 104 is radiated to the outside of the processing chamber 104 through the window 106. Outside the window 106, a light-emitting monitor 170 is provided. The light-emitting monitor 170 receives light leaked from the window 106, and measures the intensity of light emitted by each element in the plasma according to the received light at each wavelength. In this embodiment, the light emission monitor 170 measures the light emission intensity of light corresponding to the wavelength of the Ti element.

A plurality of exhaust ports 159 are formed at an edge portion or a corner portion of the bottom wall of the processing 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; and an APC (Auto Pressure Controller) valve 162 that controls the pressure in the processing chamber 104 by adjusting the opening and closing degree of the exhaust pipe 161 And a vacuum pump 163 for exhausting the inside of the processing chamber 104 through the exhaust pipe 161. The inside of the processing chamber 104 is exhausted by the vacuum pump 163, and the pressure in the processing chamber 104 is maintained at a predetermined pressure by adjusting the opening and closing degree of the APC valve 162 in the etching process by plasma.

The control unit 20 includes a memory and a processor. The processor in the control section 20 reads out and executes a program stored in the memory of the control section 20, thereby controlling each section of the main body 10. The specific processing performed by the control unit 20 will be described later.

[Formation Process of Element D] 此 Here, a part of a formation process of a plurality of elements D provided on the substrate W to be processed will be described. FIG. 2 is a schematic diagram showing an example of an electrode formation process of a TFT, ie, a device D, having a bottom gate structure. In the electrode formation process of the element D on the substrate W to be processed, first, a gate electrode is formed on a substrate such as a glass substrate, and a gate insulating film 30 is laminated on the gate electrode. Then, as shown in FIG. 2 (a), a semiconductor layer 31 is laminated on the gate insulating film 30, for example. In this embodiment, the semiconductor layer 31 is an oxide semiconductor made of, for example, indium (In), gallium (Ga), and zinc (Zn). An oxide semiconductor, that is, a semiconductor layer 31, constitutes a channel of a TFT.

After the semiconductor layer 31 is patterned into a predetermined shape, the electrode layer 32 is laminated so as to cover the semiconductor layer 31. The electrode layer 32 includes, for example, a Ti film 320, an Al film 321, and a Ti film 322 as shown in FIG. 2 (a). The electrode layer 32 is formed by laminating an Al film 321 on the Ti film 320 and a Ti film 322 on the Al film 321. The Ti film 320 is an example of a first Ti film, and the Ti film 322 is an example of a second Ti film. Furthermore, a photoresist 33 is laminated on the electrode layer 32, and the photoresist 33 is patterned into the shape of a source electrode and a drain electrode. In addition, the substrate W is exposed to a plasma containing chlorine gas, for example, as shown in FIG. 2 (b), the electrode layer 32 is etched along the pattern of the photoresist 33, and a source is formed by the electrode layer 32. Electrode and drain electrode.

However, the substrate W to be used for the FPD tends to become larger, and the body 10 of the etching apparatus 1 also becomes larger. Therefore, it becomes difficult to generate a uniform plasma in the processing chamber 104, and it becomes difficult to uniformly process a plurality of elements D arranged on the substrate W to be processed.

Here, consider the case where the electrode layer 32 is etched using a type 1 gas containing chlorine in the substrate W to be processed shown in FIG. 2 (a). When there is a deviation in the plasma distribution in the processing chamber 104, the etching rate becomes higher in the part where the plasma density is high on the substrate W to be processed, and the etching rate becomes lower in the part where the plasma density is low. . Therefore, among the plurality of elements D provided on the substrate W to be processed, the etching rate of the element D varies depending on the portion on the substrate W to be processed.

In the element D located at a high plasma density position, for example, as shown in FIG. 3 (a), the electrode layer 32 is rapidly etched, and the source layer and the drain electrode are formed early by the electrode layer 32. FIG. 3 is a schematic diagram showing an example of an electrode formation process of the element D in the comparative example.

On the other hand, the element D located at a position where the plasma density is low has a lower etching rate than the element D located at a position where the plasma density is high. Therefore, as shown in FIG. 3 (a), for example, the element D located at a position where the plasma density is high is the element D located at a position where the etching rate is low, even if the etching of the electrode layer 32 is completed. For example, as shown in FIG. 3 (b), the etching of the electrode layer 32 has not been completed.

Even in the element D at a low etching rate, as long as the etching is continued, as shown in FIG. 3 (d), the source electrode and the drain electrode can be formed soon after the bottom of the trench reaches the semiconductor layer 31. However, in this case, since the element D disposed in the high-density region of the plasma is etched by the electrode layer 32 and further etched after the semiconductor layer 31 is exposed, for example, as shown in FIG. 3 (c ), The semiconductor layer 31 is etched. Therefore, the semiconductor layer 31 of the element D located at a place with a high plasma density consumes more than the semiconductor layer 31 of the element D located at a place with a low plasma density.

In addition, even if the consumption of the semiconductor layer 31 caused by the plasma is small, the semiconductor layer 31 of the element D arranged in a region with a high density of the plasma is exposed to the plasma for a longer time than the density of the plasma. The semiconductor layer 31 of the element D in the lower region is longer. As a result, characteristics such as desorption of oxygen atoms occur in the semiconductor layer 31. Therefore, the variation in the characteristics of the semiconductor layer 31 in each element D on the substrate W to be processed becomes large.

Therefore, in this embodiment, the gas supplied into the processing chamber 104 is switched to a gas having a large selection ratio of the Al film to the Ti film during the etching of the Al film 321. Thereby, the time difference between the element D arranged in a high plasma density region and the element D arranged in a low plasma density region can be reduced until the semiconductor layer 31 is exposed by etching. Thereby, the consumption amount of the semiconductor layer 31 in the element D arranged in the high-density region of the plasma can be reduced, and the time during which the semiconductor layer 31 is exposed to the plasma can be shortened. Thereby, variations in the characteristics of the semiconductor layer 31 in each element D on the substrate W to be processed can be suppressed, and the quality of the FPD can be improved.

Specifically, the electrode layer 32 is etched to the middle of the Al film 321 in the electrode layer 32 by a plasma containing chlorine gas. Thus, the element D arranged in a region with a high plasma density and the element D arranged in a region with a low plasma density are, for example, electrode layers as shown in FIGS. 4 (a) and 4 (b). The etching amount of 32 produces a large difference. FIG. 4 is a schematic diagram showing an example of an electrode formation process of the element D in this embodiment. Figures 4 (a), (c), and (e) are examples of the electrode formation process of the element D arranged in the high-density area of the plasma. Figures 4 (b), (d), and (f) are An example of an electrode formation process of the element D arranged in a low-density region of the plasma is shown.

Furthermore, in the element D arranged in the high-density region of the plasma, at the stage where the Al film 321 is etched, the gas supplied into the processing chamber 104 is switched to an Al film to Ti film having a larger selection ratio gas. As a result, the etching rate of the Al film 321 in the element D arranged in the region where the plasma density is low is higher than the etching rate of the Ti film 320 in the element D arranged in the region with high plasma density. Therefore, the element D arranged in a region with a high plasma density and the element D arranged in a region with a low plasma density are, for example, as electrode layers as shown in FIGS. 4 (c) and 4 (d). The difference in the overall etching rate of 32 becomes smaller. Thereby, the consumption amount of the semiconductor layer 31 in the element D arranged in the high-density area of the plasma can be reduced, and the time of exposure to the plasma can be shortened.

In addition, in this embodiment, as a gas having a large selection ratio of the Al film to the Ti film, a mixed gas of Cl ₂ gas and N ₂ gas is used. However, when the semiconductor layer 31 is exposed to a plasma of N ₂ gas, the surface may be nitrided and the characteristics may be changed. Thus, in the D element disposed in the area of high-density plasma, before the semiconductor layer 31 is exposed, the etching gas is switched from the mixed gas of Cl ₂ gas and the N ₂ gas containing no N ₂ gas into the etching gas. Furthermore, the electrode layer 32 is continuously etched by the plasma without an etching gas containing N ₂ gas, and the element D disposed in a region with a high plasma density and the element D disposed in a region with a low plasma density are used. In FIG. 4 (e) and FIG. 4 (f), the electrode layer 32 is etched.

[Selection Ratio of Etching Gas] Here, experimental results regarding a gas having a large selection ratio of an Al film to a Ti film will be described. FIG. 5 is a graph showing an example of an experimental result of an etching rate and a selection ratio when a flow rate of N ₂ gas is changed with respect to a flow rate of Cl ₂ gas.

When only Cl ₂ gas is used (that is, when the flow rate of N ₂ gas is set to 0), for example, as shown in FIG. 5, the etching rate of Al is 224 (nm / min), and The etching rate was 161 (nm / min). In this case, the selection ratio of Al to Ti is about 1.39.

When the ratio of the flow rate of the Cl ₂ gas to the flow rate of the N ₂ gas is 4: 1, for example, as shown in FIG. 5, the etching rate of Al is 194 (nm / min), and the etching rate of Ti is 194 (nm / min). It was 111 (nm / min). In this case, the selection ratio of Al to Ti is about 1.75.

When the ratio of the flow rate of the Cl ₂ gas to the flow rate of the N ₂ gas is set to 3: 2, for example, as shown in FIG. 5, the etching rate of Al is 145 (nm / min) and the etching rate of Ti is It was 81 (nm / min). In this case, the selection ratio of Al to Ti is about 1.79.

In this way, in the etching gas, the more the flow rate of the N ₂ gas added by the Cl ₂ gas, the more the selection ratio of Al to Ti increases. In the etching gas switched during the etching of the Ti film 320, the higher the selection ratio of Al to Ti, the element D arranged in a region with a high plasma density and the element arranged in a region with a low plasma density In D, it is possible to reduce the difference in etching rate in the entire electrode layer 32.

In addition, it can be said that, as long as the N ₂ gas is added, compared with the case where the electrode layer 32 is etched with only Cl ₂ gas, the selectivity ratio of Al to Ti becomes higher. Therefore, in each element D, the entire electrode layer 32 can be reduced. The difference in etching rate. The reason why the selectivity ratio of Al to Ti is increased by adding N ₂ gas is that the surface of Ti is considered to be nitrided and difficult to etch. In addition, since Al and Ti cannot be etched with only N ₂ gas, even if the amount of N ₂ gas is increased, the etching gas must contain at least Cl gas. In addition, according to the experimental results shown in FIG. 5, the ratio of the flow rate of the N ₂ gas to the fluid of the Cl ₂ gas is preferably 25% or more. The ratio of the flow rate of N ₂ gas to the fluid of Cl ₂ gas is more preferably 25% to 67%.

[Switching Timing of Etching Gas] FIG. 6 is a schematic diagram showing an example of changes in luminous intensity of the Ti element and the Al element during etching. For example, when the target substrate W on which the element D shown in FIG. 2 (a) is formed is etched by a plasma of Cl ₂ gas, first, the Ti film 322 in the electrode layer 32 is etched. Thereby, the Ti element detached from the Ti film 322 starts to drift into the processing chamber 104. For example, as shown in FIG. 6, in the processing chamber 104, the luminous intensity of light corresponding to the wavelength of the Ti element starts to increase.

Furthermore, in the element D arranged in the high-density region of the plasma, when the Al film 321 is exposed, the light emission intensity of light corresponding to the wavelength of the Ti element is reduced in the processing chamber 104 while corresponding to the Al element. The luminous intensity of the light of the wavelength starts to increase.

Moreover, even in the element D arranged in the region where the density of the plasma is low, when the Al film 321 is also exposed, the luminous intensity of light corresponding to the wavelength of the Ti element in the processing chamber 104 becomes the smallest, corresponding to the Al element. The luminous intensity of the light of the wavelength becomes maximum.

Further, etching is performed, and in the element D arranged in the high-density region of the plasma, the timing t ₁ at which the Ti film 320 is exposed, for example, as shown in FIG. 6, corresponds to the wavelength of the Al element in the processing chamber 104. At the same time that the luminous intensity of the light is reduced, the luminous intensity of the light corresponding to the wavelength of the Ti element starts to increase again.

In this embodiment, the light emission intensity of light corresponding to the wavelength of the Ti element is changed from decreasing to increasing at a time t ₁ , and the gas supplied into the processing chamber 104 is switched to a film having a larger selection ratio of the Al film to the Ti film. gas. Specifically, N ₂ gas is added to Cl ₂ gas. Cl ₂ gas is an example of the first processing gas, and a mixed gas containing Cl ₂ gas and N ₂ gas is an example of the second processing gas. As a result, the remaining Al film 321 is etched more quickly in the element D arranged in the region where the plasma density is low, and the etching rate of the Ti film 320 in the element D arranged in the region where the plasma density is high is increased. decline. Therefore, the difference between the etching rate of the electrode layer 32 as a whole can be reduced between the element D arranged in a region with a low plasma density and the element D arranged in a region with a high plasma density.

Further, etching is performed, and even in the element D arranged in the low-density region of the plasma, the timing t ₂ at which the Ti film 320 is exposed, for example, as shown in FIG. 6, corresponds to the Al element in the processing chamber 104. The reduction rate of the luminous intensity of light with a wavelength of light and the increase rate of the luminous intensity of light with a wavelength corresponding to Ti element are both less than a predetermined value (for example, 0).

In this embodiment, the increase rate of the luminous intensity of the light corresponding to the wavelength of the Ti element becomes a time t ₂ below a predetermined value, and the gas supplied into the processing chamber 104 is restored to the original etching gas. Specifically, the addition of N ₂ gas is stopped and the supply of Cl ₂ gas is resumed. Thereby, the etching of the Ti film 320 can prevent the surface of the semiconductor layer 31 from being exposed to the N ₂ gas when the semiconductor layer 31 below the Ti film 320 is exposed.

Further, further etching is performed. When the semiconductor layer 31 is exposed in the element D arranged in the high-density region of the plasma, the luminous intensity of light corresponding to the wavelength of the Ti element starts to decrease in the processing chamber 104. Moreover, even in the element D arranged in the region where the plasma density is low, at the timing t ₃ when the semiconductor layer 31 is exposed, the reduction amount of the light emission intensity of the light corresponding to the wavelength of the Ti element becomes less than a predetermined value (for example, 0). . At timing t ₃ , the etching of the electrode layer 32 is completed even in the element D arranged in the region where the density of the plasma is low. Therefore, the etching of the electrode layer 32 of all the elements D is completed.

[Etching Process] FIG. 7 is a flowchart showing an example of the etching process. The etching process shown in FIG. 6 is executed under the control of the control unit 20.

First, the gate valve G is opened, and the substrate W to be processed is carried into the processing chamber 104 (S100). The substrate W to be processed is placed on the electrostatic jig 132 of the mounting table 130, and the gate valve G is closed. The control unit 20 controls a switch (not shown) so that a DC voltage from the DC power source 148 is applied to the electrode 146 via the power supply line 147. Thereby, the to-be-processed substrate W is attracted and hold | maintained on the electrostatic chuck 132. The control unit 20 controls a temperature adjustment mechanism (not shown) to adjust the substrate W to be processed to a predetermined temperature.

Next, the control unit 20 controls the APC valve 162 and the vacuum pump 163 to exhaust the inside of the processing chamber 104 to a predetermined vacuum degree. The control unit 20 controls the MFC 122a so as to control the valve 123a to be in an open state so that the Cl ₂ gas supplied from the gas supply source 121a becomes a predetermined flow rate. As a result, the supply of Cl ₂ gas into the processing chamber 104 is started through the gas supply pipe 124 (S101). The valve 123b is controlled to be closed. Step S101 is an example of a supply process.

Next, the control unit 20 controls the high-frequency power source 115 so that high-frequency power of, for example, 13.56 MHz is applied to the antenna 113. Thereby, a magnetic field is generated in the processing chamber 104 below the antenna 113 through the dielectric wall 102, and an induced electric field is generated in the processing chamber 104 by the generated magnetic field. Thereby, the electrons in the processing chamber 104 are accelerated by the induced electric field, and the accelerated electrons will collide with the molecules or atoms of the Cl ₂ gas introduced into the processing chamber 104, thereby generating inductive coupling in the processing chamber 104. Plasma (S102).

The control unit 20 controls the high-frequency power source 153 so that high-frequency power of, for example, 3.2 MHz is applied to the substrate 131. Thereby, ions are introduced onto the substrate W to be processed, and etching of the electrode layer 32 of each element D on the substrate W to be processed is started. In this way, in step S102, a plasma of Cl ₂ gas is generated in the processing chamber 104, and thereby the Ti film 322 contained in the electrode layer 32 of each element D is etched. In any element, the Al film 321 contained in the electrode layer 32 of each element D is etched until the Ti film 320 is exposed. Step S102 is an example of the first etching process.

Next, the control unit 20 refers to the measurement result by the light emission monitor 170 to determine whether the light emission intensity of the light of the wavelength of the corresponding Ti element has changed from decreasing to increasing (S103). Step S103 is an example of the first determination process. When the luminous intensity of the light corresponding to the wavelength of the Ti element is changed from decreasing to increasing (S103: Yes), the control unit 20 controls the valve 123b to be in an open state so that N ₂ supplied from the gas supply source 121b The MFC 122b is controlled so that the gas becomes a predetermined flow rate. The control unit 20 controls the MFC 122 a and the MFC 122 b so that the ratio of the flow rate of the N ₂ gas to the fluid of the Cl ₂ gas becomes, for example, 67%. Thereby, the gas supplied into the processing chamber 104 is switched from Cl ₂ gas to a mixed gas containing Cl ₂ gas and N ₂ gas, and the supply of Cl ₂ gas and N ₂ gas to the processing chamber is started through the gas supply pipe 124. 104 (S104). Step S104 is an example of the first switching project. In addition, the electrode layer 32 of each element D is etched by a plasma of a mixed gas of Cl ₂ gas and N ₂ gas. The etching in step S104 performed after the gas supplied to the processing chamber 104 is switched is an example of the second etching process.

Next, the control unit 20 refers to the measurement result by the light emission monitor 170 to determine whether the increase rate of the light emission intensity of the light of the wavelength of the corresponding Ti element is equal to or less than a predetermined value (S105). Step S105 is an example of the second determination process. When the increase rate of the luminous intensity of light of the wavelength of the corresponding Ti element is equal to or less than a predetermined value (S105: Yes), the control unit 20 controls the valve 123b to a closed state and stops N ₂ from the gas supply source 121b Supply of gas (S106). Thereby, the gas supplied into the processing chamber 104 is switched from a mixed gas containing a Cl ₂ gas and an N ₂ gas to a Cl ₂ gas which is an example of a third processing gas not containing a nitrogen element. Step S106 is an example of the second handover project. The plasma of the electrode layer 32 of each element D is continued by the plasma of the Cl ₂ gas. The etching in step S106 performed after the gas supplied to the processing chamber 104 is switched is an example of the third etching process.

Next, the control unit 20 refers to the measurement result caused by the light emission monitor 170 and determines whether the light emission intensity of the light of the wavelength of the corresponding Ti element has decreased, and whether the reduction rate has fallen below a predetermined value (S107). When the reduction rate of the luminous intensity of the light of the wavelength of the corresponding Ti element is less than a predetermined value (S107: Yes), the control unit 20 controls the high-frequency power source 115 and the high-frequency power source 153 so that the antenna 113 and the base The supply of high-frequency power to the material 131 is stopped. Thereby, the generation of the plasma in the processing chamber 104 is stopped (S108). The control unit 20 controls the valve 123a to a closed state, and stops the operations of the APC valve 162 and the vacuum pump 163. The control unit 20 controls a switch (not shown) to stop the application of a DC voltage from the DC power source 148 to the electrode 146 and raises a plurality of lift pins (not shown). Then, the gate valve G is opened, and the processing target substrate W is carried out from the processing chamber 104 (S109).

[Hardware of Control Unit] FIG. 8 is a diagram showing an example of the hardware of the control unit 20. The control unit 20 includes, for example, a CPU (Central Processing Unit) 21, a RAM (Random Access Memory) 22, a ROM (Read Only Memory) 23, an auxiliary memory device 24, and a communication interface (I / F), as shown in FIG. 25. Input / output interface (I / F) 26 and media interface (I / F) 27.

The CPU 21 operates in accordance with a program stored in the ROM 23 or the auxiliary memory device 24 and controls each unit. The ROM 23 stores a booting program executed by the CPU 21 when the control unit 20 is started, or a program that depends on the hardware of the control unit 20.

The auxiliary memory device 24 is, for example, a HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores a program executed by the CPU 21 and data used by the program. The CPU 21 is a program stored in the auxiliary memory device 24, for example, read from the auxiliary memory device 24, loads it into the RAM 22, and executes the loaded program. The communication I / F 25 receives signals from various parts of the main body 10 via a communication cable and sends them to the CPU 21, and sends signals generated by the CPU 21 to various parts of the main body 10 via a communication cable.

The CPU 21 is an output device such as a monitor and an input device such as a keyboard or a mouse via an input / output I / F 26. The CPU 21 obtains data from the input device via the input / output I / F 26. The CPU 21 outputs the generated data to the output device via the input / output I / F 26.

The media I / F 27 reads programs or data stored in the recording medium 28 and stores the programs or data in the auxiliary memory device 24. The recording medium 28 is an optical recording medium such as a DVD (Digital Versatile Disc) or a PD (Phase change rewritable Disk), a magneto-optical recording medium such as a MO (Magneto-Optical disk), a tape medium, a magnetic recording medium, or a semiconductor memory.体 等。 Body and so on. In addition, the control unit 20 may obtain a program or the like stored in the auxiliary memory device 24 from another device via a communication cable or the like, and store the obtained program or the like in the auxiliary memory device 24.

The embodiment of the etching apparatus 1 has been described above. As can be clearly understood from the above description, according to the etching apparatus 1 of this embodiment, the consumption of the semiconductor layer 31 in the element D disposed in a region with a high plasma density can be reduced, and the density disposed in the plasma can be shortened. Time when the semiconductor layer 31 in the element D in the high area is exposed to the plasma. This can improve the quality of FPD.

[Others] 本 The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the gist thereof.

For example, in the above-mentioned embodiment, the electrode layer 32 of each element D is etched, and the electrode layer 32 is etched to the middle of the Al film 321 by the plasma of the first processing gas, and thereafter, N ₂ gas is added. The etching is continued by the plasma of the mixed gas of the first processing gas and the N ₂ gas. The first processing gas is, for example, a Cl ₂ gas. However, the technology disclosed in this case is not limited to this. For example, the first processing gas may be a mixed gas of BCl ₃ gas and Cl ₂ gas. In this case, during the etching of the electrode layer 32 of each element D, the electrode layer 32 is etched by the plasma of a mixed gas of BCl ₃ gas and Cl ₂ gas until the middle of the Al film 321, and thereafter, BCl is stopped ₃ gas supply, N ₂ gas was added, and etching was continued by a plasma of a mixed gas of Cl ₂ gas and N ₂ gas. The first processing gas may be other chlorine-containing gas such as BCl ₃ gas or CCl ₄ gas in addition to the Cl ₂ gas.

In addition, a gas to which the N ₂ gas is added as the first processing gas may be used as the second processing gas. Thereby, the structure of the gas supply mechanism 120 can be simplified.

In the above-mentioned embodiment, although the increase rate of the luminous intensity of the light corresponding to the wavelength of the Ti element is at a time t ₂ (see FIG. 6), the additive of the N ₂ gas is stopped and restarted. Supply of Cl ₂ gas, but the technology disclosed in this application is not limited to this. For example, as shown in FIG. 6, the time t ₂ at which the increase rate of the light emission intensity of the light corresponding to the wavelength of the Ti element becomes less than a predetermined value is that the light emission intensity of the light corresponding to the wavelength of the Al element becomes low. Therefore, the luminous intensity of the light corresponding to the wavelength of the Al element can be monitored instead of the increase rate of the luminous intensity of the light corresponding to the wavelength of the Ti element. When the luminous intensity of the light corresponding to the wavelength of the Al element falls below a predetermined threshold , Stop the addition of N ₂ gas, and start the supply of Cl ₂ gas again.

Moreover, in the above-mentioned embodiment, although the etching apparatus 1 which performs etching using the inductive coupling plasma as a plasma source was demonstrated as an example, the technique disclosed by this case is not limited to this. As long as the etching device 1 uses a plasma to etch, the plasma source is not limited to an inductively coupled plasma. For example, any plasma source such as a capacitive coupling plasma, a microwave plasma, and a magnetron plasma can be used.

D‧‧‧Element

G‧‧‧Gate valve

W‧‧‧Processed substrate

1‧‧‧etching device

10‧‧‧ Ontology

20‧‧‧Control Department

101‧‧‧ chamber

102‧‧‧ Dielectric Wall

103‧‧‧ Antenna Room

104‧‧‧Processing Room

106‧‧‧ windows

111‧‧‧ shower head frame

113‧‧‧antenna

115‧‧‧High-frequency power

120‧‧‧Gas supply mechanism

130‧‧‧mounting table

131‧‧‧ substrate

132‧‧‧ static clamp

148‧‧‧DC Power Supply

153‧‧‧High-frequency power

160‧‧‧Exhaust mechanism

170‧‧‧light monitor

30‧‧‧Gate insulation film

31‧‧‧Semiconductor layer

32‧‧‧ electrode layer

320‧‧‧Ti film

321‧‧‧Al film

322‧‧‧Ti film

33‧‧‧Photoresist

FIG. 1 is a diagram showing an example of an etching apparatus. [Fig. 2] Fig. 2 is a schematic diagram showing an example of an electrode formation process of a TFT, which is a bottom gate structure, which is an element. [Fig. 3] Fig. 3 is a schematic diagram showing an example of an electrode formation process of an element in a comparative example. [Fig. 4] Fig. 4 is a schematic diagram showing an example of an electrode formation process of the element in this embodiment. [Fig. 5] Fig. 5 is a graph showing an example of an experimental result of an etching rate and a selection ratio when a flow rate of N ₂ gas is changed with respect to a flow rate of Cl ₂ gas. [Fig. 6] Fig. 6 is a schematic diagram showing an example of changes in luminous intensity of the Ti element and the Al element during etching. FIG. 7 is a flowchart showing an example of an etching process. [Fig. 8] Fig. 8 is a diagram showing an example of hardware of a control unit.

Claims (9)

An etching method comprising: a moving-in process, moving a substrate to be processed in which a plurality of elements "forming an electrode layer on a semiconductor layer" are provided into a chamber, the electrode layer being laminated on the first Ti film Al film, a second Ti film is laminated on the Al film; a supply process to supply a first processing gas into the chamber; a first etching process to etch each of the chambers with a plasma of the first processing gas; The second Ti film contained in the electrode layer of the aforementioned element, and in any of the aforementioned elements, the Al film contained in the electrode layer of each of the aforementioned elements is etched until the first Ti film is exposed; the first switching process will be performed The processing gas supplied into the chamber is switched from the first processing gas to the second processing gas containing N ₂ gas; and the second etching process is started again in the chamber by the plasma of the second processing gas. The electrode layer of each of the aforementioned elements is etched. For example, the etching method in the scope of patent application No. 1 further includes: The first determination process, which measures the luminous intensity of light corresponding to the wavelength of the Ti element in the space existing in the chamber in the first etching process, and determines Whether the luminous intensity decreases and then increases. In the first switching process, the first judging process is performed. When it is determined that the luminous intensity decreases and increases, it will be supplied to the chamber for treatment. The gas is switched from the first processing gas to the second processing gas. For example, the etching method of item 1 or 2 of the patent application scope, wherein the first processing gas is a Cl ₂ gas or a mixed gas of BCl ₃ gas and Cl ₂ gas, and the second processing gas is a Cl ₂ gas and N ₂ A mixture of gases. For example, the etch method of item 1 or 2 of the scope of patent application, which further includes: The second switching process, after the aforementioned second etching process, the aforementioned first Ti film among all the aforementioned elements is exposed and then supplied to the aforementioned chamber. The processing gas is switched from the second processing gas to the third processing gas containing no nitrogen element; and in the third etching process, each of the aforementioned elements is restarted in the chamber by the plasma of the third processing gas. The aforementioned electrode layer is etched. For example, the etching method of item 4 of the scope of patent application further includes: The second determination process, which measures the luminous intensity of light corresponding to the wavelength of the Ti element in the space existing in the chamber in the second etching process, and determines Whether the increase rate of the luminous intensity is less than a predetermined value. 值 In the second switching process, the second determination process is performed. When it is determined that the increase rate of the luminous intensity is less than the predetermined value, it will be determined. The processing gas supplied into the chamber is switched from the second processing gas to the third processing gas. For example, the etching method according to item 4 of the patent application range, wherein the third processing gas is a mixed gas of BCl ₃ gas and Cl ₂ gas or Cl ₂ gas. For example, the etching method according to item 1 or 2 of the scope of patent application, wherein: the aforementioned semiconductor layer is an oxide semiconductor. For example, the etching method according to item 7 of the scope of patent application, in which the aforementioned oxide semiconductor constitutes a channel of a TFT (Thin Film Transistor). An etching device is characterized in that it includes: a chamber; a mounting table disposed in the chamber, and a substrate to be processed on which a plurality of elements for forming an electrode layer on a semiconductor layer are placed, and the electrode layer An Al film is laminated on the first Ti film, and a second Ti film is laminated on the Al film; a supply unit for supplying a processing gas into the chamber; a generation unit in a state where the substrate to be processed is placed on the mounting table Generating a plasma supplied to the processing gas in the chamber; and a control unit, the control unit, performing: a first etching process, controlling the supply unit so that the first processing gas is supplied into the chamber, and The generation unit is controlled to generate a plasma of a first processing gas in the chamber, thereby etching the second Ti film contained in the electrode layer of each of the elements, and etching the foregoing of each of the elements in any of the foregoing elements. The Al film contained in the electrode layer until the first Ti film is exposed; the switching process is controlled to control the supply unit to be supplied to the processing gas in the chamber; Switching from the first process gas into the second process gas comprising N ₂ gas; and a second etching step, the control unit generating, to generate plasma of the second gas in the treatment chamber, whereby the respective start again Etching of the aforementioned electrode layer of the aforementioned device.