JP2021197378A - Etching method and substrate processing device - Google Patents

Abstract

To provide an etching method and a substrate processing device that stably control the pressure in a processing chamber.SOLUTION: An etching method includes a step of arranging a substrate on which a laminated film having a first titanium film and an underlying aluminum film is formed, a step of etching the first titanium film while automatically controlling the opening degree of a pressure control valve, a step of calculating a first opening degree value from an opening degree value of the pressure control valve sampled in the step of etching the titanium film, a step of setting the opening degree of the pressure control valve to the first opening degree value at the start of etching of the aluminum film and etching the aluminum film, a step of monitoring the pressure in the step of etching the aluminum film, and changing the first opening degree value to the second opening degree value by a predetermined amount of change when the pressure exceeds a threshold value, and a step of performing changing to the second opening degree value once or more until the etching of the aluminum film is completed.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to an etching method and a substrate processing apparatus.

For example, Patent Document 1 carries in a substrate having a laminated film of a titanium film, an aluminum film, and a lower layer of a titanium film on which a patterned photoresist layer is formed, and uses the laminated film. We are proposing plasma etching. In Patent Document 1, the processing chamber is adjusted to a predetermined degree of vacuum by automatic control of a pressure control valve, an etching gas containing a chlorine-containing gas is supplied to the processing chamber as the processing gas, the processing gas is turned into plasma, and the laminated film is plasma. Etch.

Japanese Unexamined Patent Publication No. 2018-41890

The present disclosure provides an etching method and a substrate processing apparatus capable of stably controlling the pressure in the processing chamber.

According to one aspect of the present disclosure, (a) a step of arranging a substrate on which a laminated film having a first titanium film and an aluminum film under the first titanium film is formed in a processing chamber, (a). b) A mask made of an organic material while automatically controlling the opening degree of the pressure control valve according to a change in pressure in the processing chamber or the exhaust pipe connected to the exhaust device by an exhaust pipe via a pressure control valve. The step of etching the first titanium film via the above, (c) the step of calculating the first opening value from the opening value of the pressure control valve sampled in (b), and (d). ) The step of setting the opening degree of the pressure control valve to the first opening value at the start of etching of the aluminum film and etching the aluminum film, and (e) monitoring the pressure in the above (d). (F) The step of changing the first opening value to a second opening value by a predetermined change amount when the pressure exceeds a predetermined threshold. An etching method is provided in which the above (e) is performed one or more times until the etching of the aluminum film is completed.

According to one aspect, the pressure in the processing chamber can be stably controlled.

It is sectional drawing which shows an example of the substrate processing apparatus which concerns on embodiment. It is a figure which shows an example of the control of a pressure control valve and the vibration of pressure which concerns on embodiment in comparison with a reference example. It is a figure which shows an example of the arrangement of the pressure gauge which concerns on embodiment. It is a flowchart which shows the etching method which concerns on embodiment. It is a figure which shows the EPD control which concerns on embodiment in comparison with the time control of a reference example. It is a figure which shows the other film structure to which the etching method which concerns on embodiment is applied.

Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. In each drawing, the same components may be designated by the same reference numerals and duplicate explanations may be omitted.

[Board processing equipment]
First, an example of the substrate processing apparatus according to the embodiment of the present disclosure will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of a substrate processing apparatus according to an embodiment.

The substrate processing apparatus 100 is an inductively coupled plasma (ICP) processing apparatus that executes various substrate processing methods on a rectangular substrate (hereinafter, simply referred to as “substrate”) G for FPD. be. As the material of the substrate, glass is mainly used, and depending on the application, a transparent synthetic resin or the like may be used. Here, the substrate treatment includes an etching treatment, a film forming treatment using a CVD (Chemical Vapor Deposition) method, and the like. An example of the FPD is a liquid crystal display (LCD). It may be Electro Luminescence (EL), Plasma Display Panel (PDP), or the like. The substrate G includes a support substrate as well as a form in which a circuit is patterned on the surface thereof. In addition, the plane dimensions of the FPD substrate are increasing in scale with the passage of generations. The planar dimensions of the substrate G processed by the substrate processing apparatus 100 include, for example, from the dimensions of about 1500 mm × 1800 mm of the 6th generation to the dimensions of about 3000 mm × 3400 mm of the 10.5 generation. Further, the thickness of the substrate G is about 0.2 mm to several mm.

The substrate processing apparatus 100 includes a rectangular parallelepiped box-shaped processing container 10, a substrate mounting table 60 having a rectangular outer shape arranged in the processing container 10 on which the substrate G is placed, and a control unit 90. Have. The processing container 10 may have a cylindrical box shape, an elliptical tubular box shape, or the like. In this form, the substrate mounting table 60 is also circular or elliptical, and is mounted on the substrate mounting table 60. The substrate G is also circular or the like.

The processing container 10 is divided into two upper and lower spaces by a dielectric plate 11, an antenna chamber which is an upper space is formed by an upper chamber 12, and a processing chamber S which is a lower space is formed by a lower chamber 13. The processing container 10 is made of a metal such as aluminum, and the dielectric plate 11 is made of ceramics such as _{alumina (Al 2} O _{3) or quartz.}

In the processing container 10, a rectangular annular support frame 14 is arranged so as to project inside the processing container 10 at a position at the boundary between the lower chamber 13 and the upper chamber 12, and a dielectric material is provided on the support frame 14. The plate 11 is placed. The processing container 10 is grounded by the ground wire 13e.

The side wall 13a of the lower chamber 13 is provided with a carry-in / out port 13b for carrying in / out the substrate G to / from the lower chamber 13, and the carry-in / out port 13b can be opened and closed by a gate valve 20. A transfer chamber containing a transfer mechanism (neither is shown) is adjacent to the lower chamber 13, and the gate valve 20 is controlled to open and close, and the transfer mechanism carries in and out the substrate G via the carry-in / out port 13b. Will be.

Further, a plurality of openings 13c are opened at intervals on the side wall 13a of the lower chamber 13, and a quartz observation window 25 is attached to the outside of each opening 13c so as to close the opening 13c. ing. An emission spectroscopic analyzer 55 is attached to the outside of the observation window 25 via an optical fiber. The emission spectroscopic analyzer 55 receives the emission of plasma in the processing chamber S through the observation window 25 and measures the intensity thereof. The monitor information of the emission intensity of the plasma by the emission spectroscopic analyzer 55 is transmitted to the control unit 90. The emission spectroscopic analyzer 55 may be attached to the observation window 25 of the required opening 13c among the plurality of openings 13c.

Further, a plurality of exhaust ports 13f are provided in the bottom plate 13d of the lower chamber 13. A gas exhaust pipe 51 is connected to the exhaust port 13f, and the gas exhaust pipe 51 is connected to the exhaust device 53 via a pressure control valve 52. The gas exhaust section 50 is formed by the gas exhaust pipe 51, the pressure control valve 52, and the exhaust device 53. The exhaust device 53 has a vacuum pump such as a turbo molecular pump, and can evacuate the inside of the lower chamber 13 to a predetermined degree of vacuum during the process. A pressure gauge (CM) 54 is installed in the vicinity of the pressure control valve 52 on the upstream side (lower chamber 13 side) of the pressure control valve 52. The pressure value in the gas exhaust pipe 51 upstream of the pressure control valve 52 is measured by the pressure gauge (CM) 54 and transmitted to the control unit 90. The control unit 90 controls the opening degree of the pressure control valve 52 based on the measured pressure value.

A support beam for supporting the dielectric plate 11 is provided on the lower surface of the dielectric plate 11, and the support beam also serves as a shower head 30. The shower head 30 is made of a metal such as aluminum, and may be surface-treated by anodizing. A gas flow path 31 extending in the horizontal direction is formed in the shower head 30. A gas discharge hole 32 that extends downward and faces the processing chamber S below the shower head 30 communicates with the gas flow path 31.

A gas introduction pipe 45 communicating with the gas flow path 31 is connected to the upper surface of the dielectric plate 11. The gas introduction pipe 45 airtightly penetrates the supply port 12b provided in the ceiling 12a of the upper chamber 12 and is connected to the processing gas supply source 44 via the gas supply pipe 41 airtightly coupled to the gas introduction pipe 45. ing. An on-off valve 42 and a flow rate controller 43 such as a mass flow controller are interposed in the middle of the gas supply pipe 41. The processing gas supply unit 40 is formed by the gas introduction pipe 45, the gas supply pipe 41, the on-off valve 42, the flow rate controller 43, and the processing gas supply source 44. The processing gas supplied from the processing gas supply unit 40 is supplied to the shower head 30 via the gas supply pipe 41 and the gas introduction pipe 45, and is discharged to the processing chamber S through the gas flow path 31 and the gas discharge hole 32. ..

A high frequency antenna 15 is arranged in the upper chamber 12 forming the antenna chamber. The high frequency antenna 15 is formed by winding an antenna wire 15a formed of a good conductive metal such as copper in an annular shape or a spiral shape. For example, the annular antenna wires 15a may be arranged in multiple layers.

A feeder 16 extending above the upper chamber 12 is connected to the terminal of the antenna wire 15a, a feeder line 17 is connected to the upper end of the feeder member 16, and the feeder line 17 is a matching device 18 that performs impedance matching. It is connected to the high frequency power supply 19 via. By applying high frequency power of, for example, 10 MHz to 15 MHz from the high frequency power supply 19 to the high frequency antenna 15, an induced electric field is formed in the lower chamber 13. By this induced electric field, the processing gas supplied from the shower head 30 to the processing chamber S is turned into plasma to generate inductively coupled plasma, and the ions in the plasma are provided to the substrate G. The high-frequency power supply 19 is a source source for plasma generation, and the high-frequency power supply 73 connected to the substrate mounting table 60 is a bias source that attracts the generated ions and imparts kinetic energy. In this way, plasma is generated from the ion source source by inductive coupling, and a bias source, which is a separate power source, is connected to the substrate mounting table 60 to control the ion energy. As a result, plasma generation and ion energy control are performed independently, and the degree of freedom of the process can be increased. The frequency of the high frequency power output from the high frequency power supply 19 is preferably set in the range of 0.1 to 500 MHz.

The substrate mounting table 60 has a base material 63 and an electrostatic chuck 66 formed on the upper surface 63a of the base material 63. The plan view shape of the base material 63 is rectangular, has a plane dimension similar to that of the substrate G mounted on the substrate mounting table 60, has a long side length of about 1800 mm to 3400 mm, and has a short side length. The size can be set to about 1500 mm to 3000 mm. With respect to this plane dimension, the thickness of the base material 63 can be, for example, about 50 mm to 100 mm. The base material 63 is formed of stainless steel, aluminum, an aluminum alloy, or the like. The base material 63 is provided with a meandering temperature control medium flow path 62a so as to cover the entire area of the rectangular plane. The temperature control medium flow path 62a may be provided in, for example, an electrostatic chuck 66. Further, the base material 63 may be formed in a laminated body of two members instead of a single member as shown in the illustrated example.

At both ends of the temperature control medium flow path 62a, a feed pipe 62b in which the temperature control medium is supplied to the temperature control medium flow path 62a and a temperature control medium that has been heated through the temperature control medium flow path 62a are provided. It communicates with the discharged return pipe 62c. The feed pipe 62b and the return pipe 62c communicate with the feed flow path 82 and the return flow path 83, respectively, and the feed flow path 82 and the return flow path 83 communicate with the chiller 81, respectively. The chiller 81 has a main body that controls the temperature and discharge flow rate of the temperature control medium, and a pump that pumps the temperature control medium (neither is shown). A refrigerant is applied as the temperature control medium, and Galden (registered trademark), Fluorinert (registered trademark), and the like are applied to this refrigerant. The temperature control form of the illustrated example is a form in which the temperature control medium is circulated through the base material 63, but the base material 63 may have a built-in heater or the like and the temperature control may be performed by the heater, or the temperature control medium may be used. The temperature may be controlled by both heaters. Further, instead of the heater, the temperature control accompanied by heating may be performed by circulating a high temperature temperature control medium. The heater, which is a resistor, is formed of tungsten, molybdenum, or a compound of any one of these metals and alumina, titanium, or the like. Further, in the illustrated example, the temperature control medium flow path 62a is formed on the base material 63, but for example, the electrostatic chuck 66 may have the temperature control medium flow path.

A box-shaped pedestal 68 formed of an insulating material and having a step portion inside is fixed on the bottom plate 13d of the lower chamber 13, and a substrate mounting pedestal 60 is placed on the step portion of the pedestal 68. To.

An electrostatic chuck 66 on which the substrate G is directly placed is formed on the upper surface of the base material 63. The electrostatic chuck 66 includes a ceramic layer 64, which is a dielectric film formed by spraying ceramics such as alumina, and a conductive layer 65 (electrode) embedded inside the ceramic layer 64 and having an electrostatic adsorption function. Has. The conductive layer 65 is connected to the DC power supply 75 via the feeder line 74. When a switch (not shown) interposed in the feeder line 74 is turned on by the control unit 90, a DC voltage is applied from the DC power supply 75 to the conductive layer 65 to generate a Coulomb force. Due to this Coulomb force, the substrate G is electrostatically adsorbed on the upper surface of the electrostatic chuck 66, and is held in a state of being placed on the upper surface of the base material 63. In this way, the substrate mounting table 60 forms a lower electrode on which the substrate G is placed.

A temperature sensor such as a thermoelectric pair is arranged on the base material 63, and the monitor information by the temperature sensor is transmitted to the control unit 90 at any time. The control unit 90 executes temperature control control of the base material 63 and the substrate G based on the transmitted temperature monitor information. More specifically, the control unit 90 adjusts the temperature and flow rate of the temperature control medium supplied from the chiller 81 to the feed flow path 82. Then, the temperature control medium whose temperature is adjusted and the flow rate is adjusted is circulated in the temperature control medium flow path 62a, so that the temperature control of the substrate mounting table 60 is executed. The temperature sensor such as a thermoelectric pair may be arranged on the electrostatic chuck 66, for example.

A rectangular frame-shaped focus ring 69 is placed on the outer periphery of the electrostatic chuck 66 and on the upper surface of the pedestal 68, and the upper surface of the focus ring 69 is set to be lower than the upper surface of the electrostatic chuck 66. There is. The focus ring 69 is formed of ceramics such as alumina or quartz.

A feeding member 70 is connected to the lower surface of the base material 63. A feeder line 71 is connected to the lower end of the feeder member 70, and the feeder line 71 is connected to a high frequency power supply 73 which is a bias source via a matching box 72 that performs impedance matching. By applying high-frequency power of, for example, 2 MHz to 6 MHz from the high-frequency power supply 73 to the substrate mounting table 60, ions generated by the high-frequency power supply 19 which is a source source for plasma generation can be attracted to the substrate G. .. Therefore, in the plasma etching process, both the etching rate and the etching selectivity can be increased.

The control unit 90 is a gas exhaust unit 50 based on pressure monitor information measured by each component of the substrate processing device 100, for example, a chiller 81, a high frequency power supply 19, 73, a processing gas supply unit 40, and a pressure gauge (CM) 54. Etc. are controlled. The control unit 90 has a memory such as a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU executes a predetermined process according to a recipe (process recipe) stored in the storage area of the memory. In the recipe, control information of the substrate processing apparatus 100 for the process conditions is set. The control information includes, for example, the gas flow rate, the pressure in the processing container 10, the temperature in the processing container 10, the temperature of the base material 63, the process time, and the like.

The recipe and the program applied by the control unit 90 may be stored in, for example, a hard disk, a compact disk, a magneto-optical disk, or the like. Further, the recipe or the like may be set in the control unit 90 in a state of being housed in a storage medium that can be read by a portable computer such as a CD-ROM, a DVD, or a memory card, and may be read out. The control unit 90 also has a user interface such as an input device such as a keyboard or mouse for inputting commands, a display device such as a display that visualizes and displays the operating status of the board processing device 100, and an output device such as a printer. Have.

[Etching method]
Hereinafter, the etching method according to the present embodiment will be described while comparing with the etching methods according to Reference Examples 1 and 2. 2A shows an etching method according to Reference Example 1, FIG. 2B shows an etching method according to Reference Example 2, and FIG. 2C shows an etching method according to the present embodiment. Reference Examples 1 and 2 and the etching target film of the present embodiment both have the same film structure, and a substrate G having a laminated film in which an Al film is sandwiched between an upper Ti film and a lower Ti film is made of an organic material. Etched through a mask made of a photoresist film. The upper Ti film corresponds to the first titanium film, and the lower Ti film corresponds to the second titanium film. The Al film may be a simple substance of Al or an Al alloy such as Al—Si. The etching target film is not limited to the above three-layer structure, and may be, for example, a structure in which a mask made of an organic material is formed on two layers of an upper Ti film and an lower Al film, or an Al film. It may have a structure in which a mask made of an organic material is formed on the mask.

Further, the process conditions of the present embodiment and Reference Examples 1 and 2 were the same, and an etching gas containing a chlorine-containing gas was supplied into the lower chamber 13. It may be supplied with an inert gas such as Ar gas or N ₂ gas in addition to chlorine-containing gas as the etching gas. The laminated film of the upper Ti film, the Al film and the lower Ti film is etched by the plasma of the chlorine-containing gas in the etching gas.

In the present embodiment and Reference Examples 1 and 2, the etching gas containing chlorine-containing gas for the upper Ti film and the lower Ti film and the etching gas containing chlorine-containing gas for the Al film are the same, and are used as the chlorine-containing gas. BCl ₃ gas and Cl ₂ gas were used. However, the present invention is not limited to this, and the etching gas for the upper Ti film and the lower Ti film and the etching gas for the Al film may be partially or completely different as long as they contain a chlorine-containing gas.

The results of each etching in this embodiment and Reference Examples 1 and 2 will be described. The horizontal axis of each graph in FIG. 2 indicates time (seconds), the right side of the vertical axis indicates the pressure value measured by the pressure gauge, and the left side of the vertical axis indicates the APC position. The APC position is the position (angle) of the valve body of the pressure control valve 52, and is indicated by the rotation angle / 1000 (= encoder value / 1000 attached to the pressure control valve 52).

The pressure gauge used in Reference Example 1 is arranged at a position different from that of the pressure gauge used in the present embodiment and Reference Example 2. In Reference Example 1, the pressure in the processing chamber S was measured using a pressure gauge (CM2) 151 arranged in the CM port provided on the bottom plate 13d of the lower chamber 13 shown in FIG. Then, while the upper Ti film, the Al film, and the lower Ti film were etched, the opening degree of the pressure control valve 52 was automatically controlled based on the pressure value of the processing chamber S measured by the pressure gauge (CM2) 151. Instead of the pressure gauge (CM2) 151, the opening degree of the pressure control valve 52 may be automatically controlled based on the pressure value of the processing chamber S measured by the pressure gauge (CM1) 150.

(1) of FIGS. 2 (a), (b) and (c) shows the timing at which the etching target film switches from the upper Ti film to the Al film, and (2) shows the timing at which the etching target film changes from the Al film to the lower Ti film. Indicates the timing of switching to.

In FIG. 2A showing the etching result of Reference Example 1, the APC position shown in A1 vibrates while etching the Al film, and hunting occurs. The reason is that the drive speed of the pressure control valve 52 has a mechanical limit, so that the drive of the valve body of the pressure control valve 52 follows the change in the pressure value in the processing chamber S measured by the pressure gauge (CM2) 151. Because I couldn't do it. Further, the drive delay of the pressure control valve 52 promotes the vibration width ΔP1 of the pressure value P1, and the vibration width ΔP1 of the pressure value P1 measured by the pressure gauge (CM2) 151 while etching the Al film is 2. It became 8.8 mT (about 0.373 Pa). Further, since the position of the pressure gauge (CM2) 151 and the position of the pressure control valve 52 are separated, the pressure change measured by the pressure gauge (CM2) 151 is reflected in the pressure at the position of the pressure control valve 52. The delay also contributes to the inability of the valve body drive to follow. In this way, particles were generated by the hunting of the pressure control valve 52 generated in the etching process of the Al film, and a defect occurred.

In Reference Example 2, the pressure in the gas exhaust pipe 51 upstream of the pressure control valve 52 was measured using the pressure gauge (CM) 54 shown in FIG. Then, while the upper Ti film, the Al film, and the lower Ti film were etched, the opening degree of the pressure control valve 52 was automatically controlled based on the pressure value of the gas exhaust pipe 51 measured by the pressure gauge (CM) 54.

As a result, in FIG. 2B showing the etching result of Reference Example 2, the APC position shown in A2 vibrates while etching the Al film, and hunting occurs. However, the control of the pressure control valve 52 was controlled based on the pressure P2 in the gas exhaust pipe 51 in the vicinity of the pressure control valve 52 instead of the pressure of the processing chamber S. Therefore, the delay in transmission of the pressure change due to the separation of the positions seen in Reference Example 1 is eliminated, the control responsiveness of the pressure control valve 52 is improved, and the gas exhaust during etching of the Al film is performed. The vibration width ΔP2 of the pressure P2 in the pipe 51 was 1.1 mT (about 0.14 Pa). One of the factors for improvement is that the position of the pressure gauge (CM) 54 is moved away from the processing chamber S so that it is less susceptible to the influence of the pressure change in the processing chamber S.

Therefore, in the etching method according to the present embodiment, the pressure in the gas exhaust pipe 51 upstream of the pressure control valve 52 was measured by using the pressure gauge (CM) 54 shown in FIG. 3 as in Reference Example 2. Then, the APC position is automatically controlled in the etching of the upper Ti film and the lower Ti film, but different control is performed in the etching of the Al layer. That is, at the start of etching the Al layer, the APC position was set to the initial value. However, in a state where the APC position is fixed to the initial value while the Al layer is being etched, the APC position cannot be made to follow the pressure fluctuation in the processing chamber S or the gas exhaust pipe 51. As a result, the pressure in the processing chamber S gradually increases, which affects the process performance such as the characteristics of etching applied to the substrate G.

In order to avoid this, in the etching method according to the present embodiment, the pressure gauge (CM) 54 periodically measures the pressure in the gas exhaust pipe 51 while the Al layer is etched. Then, when the measured pressure exceeds a predetermined threshold value, the APC position is controlled to open by a predetermined amount of change from the current opening degree.

That is, for the initial value of the APC position, the first opening value is calculated from the value of the pressure control valve 52 sampled in the etching process of the upper Ti film, and the opening degree of the pressure control valve 52 at the start of etching of the Al film. Is set to the first opening value. In automatic control, normally, the APC position is sequentially changed according to the change in pressure to adjust the opening degree to operate so as to keep the pressure constant at all times, but in the present embodiment, the pressure is basically changed. The opening is fixed regardless. The present embodiment is different from the normal automatic control in that the opening degree is adjusted only when a predetermined threshold value is exceeded.

Next, in the etching step of the Al film, the pressure in the gas exhaust pipe 51 is monitored, and when the pressure exceeds a predetermined threshold value, the first opening value is changed by a predetermined amount of change. It was changed to the opening value of. Then, until the etching of the Al film is completed, every time the pressure exceeds a predetermined threshold value, the change amount is added to the second opening value to change the second opening value once. I went above.

In this embodiment, assuming that the pressure value measured by the pressure gauge (CM) 54 increases as the etching of the Al layer progresses, the change amount is added to change the second opening value. Every time the pressure exceeded a predetermined threshold value, the APC position was controlled to be further opened by the amount of change. However, not limited to this, when the pressure value measured by the pressure gauge (CM) 54 becomes lower as the etching of the Al layer progresses, the change amount is subtracted to change the second opening value, and the pressure is changed. May be controlled so that the APC position is further closed by the amount of change each time the value falls below a predetermined threshold value.

As a result, as shown in the etching result of this embodiment of FIG. 2C, the APC position shown in A3 is the opening of the initial value at the timing of (1) while the Al film is being etched. It was controlled to open gradually from the opening value of 1. As a result, it was possible to avoid the occurrence of hunting in the APC position. As a result, the vibration width ΔP3 of the pressure P3 in the gas exhaust pipe 51 while etching the Al film was reduced to 0.4 mT (about 0.0533 Pa), and stable pressure control could be performed.

In this embodiment, the average value of a plurality of sampling values including the latest sampling value of the pressure control valve 52 sampled in the etching step of the upper Ti film is calculated as the first opening value. It is desirable that the plurality of sampling values including the latest sampling value are continuous sampling values. Further, it may be a value sampled every other time or every predetermined number of times. However, the latest sampling value among the values of the pressure control valve 52 sampled in the etching step of the upper Ti film may be used as the first opening value. Further, the initial value of the APC position may be a value obtained by adding an offset value, which is a predetermined parameter, to the first opening value calculated in this way. As the offset value, a value empirically obtained by the etching method according to the present embodiment may be stored in a memory in advance as a parameter.

[Etching process]
A case where the etching method according to the present embodiment described above is executed by the substrate processing apparatus 100 will be described with reference to FIG. FIG. 4 is a flowchart showing an etching method according to an embodiment. The etching method shown in FIG. 4 is executed by the control unit 90 controlling each unit of the substrate processing apparatus 100.

When the etching method of FIG. 4 is started, the gate valve 20 is opened, and the substrate G having the laminated film of the upper layer Ti film, the Al film and the lower layer Ti film is carried in through the carry-in / out port 13b and arranged on the substrate mounting table 60. (Step S1). After carrying in the substrate G, the gate valve 20 is closed.

Next, an etching gas containing a chlorine-containing gas is supplied into the lower chamber 13, plasma is generated by the high-frequency power applied from the high-frequency power source 19, and the upper Ti film is etched while the pressure control valve 52 is automatically controlled (step). S2). The automatic control of the pressure control valve 52 may be performed based on the pressure value of the processing chamber S measured by the pressure gauge (CM2) 151 or the pressure gauge (CM1) 150, or the gas exhaust measured by the pressure gauge (CM) 54. It may be performed based on the pressure value in the pipe 51. At this time, high-frequency power is applied to the substrate mounting table 60 from the high-frequency power supply 73 to generate a bias and control the energy of ions incident on the substrate G.

While the upper Ti film is being etched, the opening degree of the pressure control valve 52 is sampled at a given cycle, and the sampled value is stored in the memory (step S3).

Next, the emission intensity of the plasma generated in the processing chamber S is detected by the emission spectroscopic analyzer 55. Then, it is determined whether or not the end point of the upper Ti film is detected by EPD (End Point Detection) control based on the emission intensity of the plasma (step S4).

In the example of FIG. 5 (c), the horizontal axis shows time (seconds), the left side of the vertical axis shows the emission intensity of aluminum having a wavelength of 396 nm, and the right side of the vertical axis shows the emission intensity of chlorine having a wavelength of 838 nm. .. As the etching of the upper Ti film progresses and the exposure of the underlying Al film progresses, the emission intensity of aluminum having a wavelength of 396 nm increases. Utilizing this, the end point of etching of the upper Ti film can be detected from the emission intensity of plasma. Specifically, it is determined that the end point has been reached when the amount of change in emission intensity falls below the threshold value, and the slope (differential amount) of the curve (including the straight line portion) indicating the change in emission intensity determines the emission intensity. The amount of change is shown. For example, the control unit 90 does not detect the end point of the upper Ti film while the slope of the curve of the change in emission intensity of aluminum having a wavelength of 396 nm (hereinafter referred to as “slope”) is equal to or higher than a preset threshold value. Is determined, the process returns to step S2, and the processes of steps S2 to S4 are repeated. As a result, the etching of the upper Ti film is advanced.

On the other hand, when the slope of the emission intensity of aluminum having a wavelength of 396 nm becomes equal to or less than a preset threshold value, it is determined that the underlying Al film is sufficiently exposed, and it is determined in step S4 that the end point of the upper Ti film is detected. Proceed to step S5. Then, the first opening value is calculated from the sampling value of the opening of the pressure control valve 52 stored in the memory (step S5). When there are a plurality of sampling values in the memory, it is preferable to calculate the average value of the plurality of sampling values including the latest sampling value as the first opening value. However, the latest sampling value may be used as the first opening value.

Next, the opening degree of the pressure control valve 52 is set to the first opening degree value, and the Al film is etched with an etching gas containing a chlorine-containing gas (step S6). At this time, 1 is set in the variable n.

Next, the pressure in the gas exhaust pipe 51 is monitored by the pressure gauge (CM) 54 (step S7). However, the pressure in the processing chamber S may be monitored by the pressure gauge (CM2) 151. Next, it is determined whether the pressure value in the gas exhaust pipe 51 is larger than a predetermined threshold value (step S8).

If the pressure value in the gas exhaust pipe 51 is equal to or less than the threshold value, the process proceeds to step S11. When the pressure value in the gas exhaust pipe 51 is larger than the threshold value, 1 is added to the variable n, and the nth opening value obtained by adding a predetermined change amount to the opening degree of the pressure control valve 52 at this time is used. Calculate (step S9). At this point, a second opening value is calculated by adding a predetermined amount of change to the first opening value.

Next, the opening degree of the pressure control valve 52 is set to the opening degree value of the nth (n = 2), and the Al film is etched (step S10). Next, the emission intensity of the plasma is detected by the emission spectroscopic analyzer 55, and it is determined whether the end point of the Al film is detected by EPD control based on the emission intensity of the plasma (step S11).

In the example of FIG. 5C, the control unit 90 determines that the end point of the Al film has not been detected while the slope of the emission intensity of aluminum having a wavelength of 396 nm is equal to or higher than a predetermined threshold value, and the process proceeds to step S7. Return and repeat the processes of steps S7 to S11. As a result, the etching of the Al film is advanced.

On the other hand, when the etching of the Al film progresses and the underlying Ti film is exposed, the emission intensity of aluminum having a wavelength of 396 nm becomes low and the slope of change becomes large. Therefore, when the slope of the emission intensity of aluminum having a wavelength of 396 nm becomes equal to or less than a preset threshold value, the control unit 90 determines that the end point of the Al film has been detected, and proceeds to step S12. Here, since the change in emission intensity is decreasing, the slope is expressed as a negative value. Therefore, the threshold is set as a negative value. Further, the threshold value in step S11 is set separately from the threshold value in step S5.

Next, similarly to the upper Ti film, the lower Ti film is etched with an etching gas containing a chlorine-containing gas while automatically controlling the pressure control valve 52 (step S12). After the etching of the lower Ti film is completed, the processed substrate G is carried out (step S13), and this processing is completed.

In the example of FIG. 5 (c), when the slope of the emission intensity of chlorine having a wavelength of 838 nm is equal to or less than a preset threshold value, the end point of the lower Ti film is detected, and further, the undercoat of the lower Ti film is overetched. After etching, the treated substrate G may be carried out and the main treatment may be completed. Chlorine having a wavelength of 838 nm is an element contained in the chlorine-containing gas that remains unconsumed in the etching of the lower Ti film. The threshold value in step S12 is also set as a threshold value different from those in step S5 and step S11.

Regarding the value of the above threshold value, for example, in the end point detection system used in the above embodiment, when the etching shifts from the upper layer Ti to Al, the threshold value is set to 200, and when the value is lower than this, the upper layer Ti It was assumed that the etching was completed. Further, when the etching shifts from Al to the lower layer Ti, the threshold value is set to -10, and when the threshold value is lower than this, the etching of Al is considered to be completed. Further, when the etching is transferred from the lower layer Ti to the base film, the threshold value is set to 20, and when the threshold value is lower than this, the etching of the base Ti is completed. However, the values of these threshold values are not essential in the invention of the present embodiment, and should be appropriately determined according to the end point detection system to be used and the like. Further, these threshold values may change depending on the etching conditions and the like.

As described above, according to the etching method according to the present embodiment, in the etching process of the Al film, the gas exhaust is performed from the state where the opening degree (APC position) of the pressure control valve 52 is set to the first opening degree value. Control is performed to gradually open the valve according to the pressure value in the tube 51. Further, the first opening value, which is the initial value of the APC position, is controlled to be optimized based on the APC position sampled at the end of the etching process of the upper Ti film. As a result, the pressure fluctuation in the processing chamber S can be suppressed and the process performance can be improved. Further, it is possible to prevent hunting of the pressure control valve 52 and suppress the generation of particles.

Ideally, the pressure in the processing chamber S is measured by the pressure gauge (CM1) 150 and the pressure gauge (CM2) 151 shown in FIG. 3 in order to minimize the influence of the pressure fluctuation in the processing chamber S on the process performance. It is preferable to directly measure. However, the pressure in the processing chamber S measured by the pressure gauge (CM2) 151 is not necessarily the same as the pressure in the exhaust space, and the pressure in the gas exhaust pipe 51 changes rapidly due to the control of the pressure control valve 52, but the processing chamber There is a certain time delay before the pressure in S changes. Therefore, in the control of the pressure control valve 52 according to the present embodiment, the pressure in the gas exhaust pipe 51 near the pressure control valve 52 is monitored by the pressure gauge (CM) 54, and the pressure measured by the pressure gauge (CM) 54. The pressure control valve 52 is controlled based on the value. As a result, the delay from controlling the opening degree of the pressure control valve 52 to the change of the pressure in the gas exhaust pipe 51 is unlikely to occur, so that the pressure followability is improved. However, in the application of this embodiment, the pressure control valve 52 may be controlled based on the pressure value measured by the pressure gauge (CM1) 150 or the pressure gauge (CM2) 151.

[EPD control]
In the etching method according to the present embodiment, the control method is switched from the automatic control of the APC position at the time of etching the upper Ti film to the given control of the APC position at the time of etching the Al film at the optimum timing by EPD control. Similarly, the control method is switched from the control of the APC position at the time of etching the Al film to the automatic control of the APC position at the time of etching the lower Ti film at the optimum timing by EPD control.

FIG. 5A is the result of etching according to Reference Example 3, and FIG. 5B is the result of etching according to this embodiment. In Reference Example 3 of FIG. 5A, switching of the APC position control method at the time of etching the upper Ti film, the etching of the Al film, and the etching of the lower Ti film was controlled at a predetermined time. FIG. 5A shows the pressure P4 measured by the pressure gauge (CM2) 151 in Reference Example 3 and the opening degree A4 of the pressure control valve 52.

In FIG. 5B, the APC position control method was switched by EPD control during etching of the upper Ti film, etching of the Al film, and etching of the lower Ti film. FIG. 5B shows the pressure P5 measured by the pressure gauge (CM) 54 in the present embodiment and the opening degree A5 of the pressure control valve 52.

The process conditions for etching the upper Ti film, the Al film, and the lower Ti film in the experiment of FIG. 5 were the same. Further, as a method for controlling the APC position at the time of etching the upper Ti film, the etching of the Al film, and the etching of the lower Ti film, the control method according to the present embodiment was used as shown in FIG.

As a result, in the case of Reference Example 3 in which the switching of the APC position control method is controlled by time, the pressure gauge (CM2) 151 is used in the etching process of the Al film as shown in the dotted frame of F1 in FIG. 5 (a). The measured pressure P4 increased, and the pressure in the exhaust space and the processing chamber S became unstable.

On the other hand, in the case of the present embodiment in which the switching of the APC position control method is controlled by EPD, the automatic control of the APC position at the time of etching the upper Ti film is switched to the control of the APC position at the time of etching the Al film at the optimum timing. I was able to. Similarly, by EPD control, it was possible to switch from the control of the APC position at the time of etching the Al film to the automatic control of the APC position at the time of etching the lower Ti film at the optimum timing. Therefore, as shown in the dotted line frame of F2 in FIG. 5B, the pressure in the exhaust space and the processing chamber S could be stabilized.

[Application examples of other membranes]
In the etching method according to the present embodiment described above, the laminated film of the upper Ti film, the Al film and the lower Ti film was used as the etching target film. However, the scope of application of the etching method according to this embodiment is not limited to this. FIG. 6 is a diagram showing another film structure to which the etching method according to the present embodiment is applied.

For example, as shown in FIG. 6A, when the single Al film 1 is used as the etching target film and is etched through the mask 2, and the mask 2 contains carbon, the Al film 1 is etched. During that time, the pressure control valve 52 vibrates. As a result, the pressure P in the processing chamber S vibrates as shown in FIG. 6 (b). It is useful to apply the etching method according to the present embodiment to such a phenomenon when etching the Al film 1.

FIG. 6C shows an example of the emission intensity I1 of Al having a wavelength of 396 nm and the emission intensity I2 of CCl having a wavelength of 278.8 nm among the emission intensities of plasma detected by the emission spectroscopic analyzer 55. According to FIGS. 6 (b) and 6 (c), when the pressure P is maximum, the emission intensity I1 of Al becomes the maximum peak, and the emission intensity I2 of CCl becomes the minimum peak. On the other hand, when the pressure P is the minimum, the emission intensity I1 of Al becomes the minimum peak, and the emission intensity I2 of CCl becomes the maximum peak.

In this phenomenon, when the pressure P in the processing chamber S increases, the Al film 1 is mainly etched, the etching rate of the Al film 1 increases, and the emission intensity I1 of Al increases. On the other hand, when the pressure P in the processing chamber S is lowered, the mask 2 is mainly etched, the etching rate of the mask 2 is increased, and the emission intensity I2 of CCl is increased because the mask 2 contains carbon. Therefore, when the opening degree of the pressure control valve 52 is automatically controlled, a phenomenon occurs in which the Al film 1 and the mask 2 are alternately etched according to the periodic fluctuation of the pressure P. The periodic fluctuation of the pressure P is caused by the fact that the progress of the etching itself causes the pressure fluctuation in each of the etching of the Al film 1 and the etching of the mask 2.

In this case, the opening degree (APC position) of the pressure control valve 52 is set to a given initial value while etching the Al film 1 as in the case of etching the Al film between the upper Ti film and the lower Ti film. Controls to gradually open or close according to the pressure value from the set state. As a result, it is possible to suppress pressure fluctuations in the processing chamber S, prevent hunting of the pressure control valve 52, and suppress the generation of particles. A given initial value can be determined, for example, by performing preliminary etching in advance and determining from the result.

As described above, according to the etching method of the present embodiment, the pressure in the processing chamber S can be stably controlled.

It should be considered that the etching method and the substrate processing apparatus according to the embodiment disclosed this time are exemplary in all respects and are not restrictive. The above embodiment can be modified and improved in various forms without departing from the scope of the attached claims and the gist thereof. The matters described in the plurality of embodiments may have other configurations within a consistent range, and may be combined within a consistent range.

The substrate processing apparatus of the present disclosure includes Atomic Layer Deposition (ALD) apparatus, Capacitively Coupled Plasma (CCP), Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), Helicon Wave Plasma ( It is applicable to any type of device (HWP).

Further, although the plasma processing device has been described as an example of the substrate processing device, the substrate processing device may be any device that performs a predetermined treatment (for example, film forming treatment, etching treatment, etc.) on the substrate. Not limited to. When plasma is not used for etching, the etching process of Al may be controlled by injecting probe light instead of plasma emission and monitoring the absorption rate in EPD control.

10 Processing container 12 Upper chamber 12a Ceiling 13 Lower chamber 13a Side wall 25 Observation window 13d Bottom plate 13f Exhaust port 30 Shower head 51 Gas exhaust pipe 52 Pressure control valve 53 Exhaust device 54 Pressure gauge (CM)
55 Emission spectroscopic analyzer 60 Board mounting table 100 Board processing device G Board S Processing room

Claims (8)

(A) A step of arranging a substrate on which a laminated film having a first titanium film and an aluminum film under the first titanium film is formed in a processing chamber.
(B) It is made of an organic material while automatically controlling the opening degree of the pressure control valve according to a change in pressure in the processing chamber or the exhaust pipe connected to the exhaust device by an exhaust pipe via a pressure control valve. The step of etching the first titanium film via a mask and
(C) A step of calculating the first opening value from the opening value of the pressure control valve sampled in the above (b), and
(D) A step of setting the opening degree of the pressure control valve to the first opening degree value at the start of etching of the aluminum film and etching the aluminum film.
(E) The pressure is monitored in the above (d), and when the pressure exceeds a predetermined threshold value, the first opening value is changed to the second opening value by a predetermined change amount. Has a process to change,
(F) An etching method in which the (e) is performed once or more until the etching of the aluminum film is completed. In the above (d), the pressure is the pressure in the exhaust pipe in the vicinity of the pressure control valve and is measured on the upstream side of the pressure control valve.
The etching method according to claim 1. The etching of (b) and the etching of (d) are carried out by converting chlorine-containing gas into plasma.
The etching method according to claim 1 or 2. The first (c) calculates the first opening value based on the values of the plurality of pressure control valves including the value of the pressure control valve last sampled in the (b).
The etching method according to any one of claims 1 to 3. In (d), the opening degree of the pressure control valve is set to a value obtained by adding a predetermined offset value to the first opening degree value at the start of etching of the aluminum film.
The etching method according to any one of claims 1 to 4. The laminated film has a second titanium film under the aluminum film and has a second titanium film.
(G) After the (f), there is a step of etching the second titanium film while automatically controlling the opening degree of the pressure control valve according to a change in pressure in the processing chamber or the exhaust pipe. ,
The etching method according to any one of claims 1 to 5. (H) A step of measuring the emission intensity of plasma in the processing chamber is provided.
Based on the emission intensity of the plasma, the etching is switched from the (b) to the (d), and the etching is switched from the (d) to the (g).
The etching method according to any one of claims 6. A substrate having a processing chamber in which a substrate is arranged, an exhaust device connected to the processing chamber by an exhaust pipe via a pressure control valve, a pressure gauge for measuring the pressure in the processing chamber or the exhaust pipe, and a control unit. It ’s a processing device,
The control unit
(A) A step of arranging a substrate on which a laminated film having a first titanium film and an aluminum film under the first titanium film is formed in the processing chamber.
(B) The first, through a mask made of an organic material, while automatically controlling the opening degree of the pressure control valve according to a change in pressure in the processing chamber or the exhaust pipe measured by the pressure gauge. The process of etching the titanium film and
(C) A step of calculating the first opening value from the opening value of the pressure control valve sampled in the above (b), and
(D) A step of setting the opening degree of the pressure control valve to the first opening degree value at the start of etching of the aluminum film and etching the aluminum film.
(E) The pressure is monitored in the above (d), and when the pressure exceeds a predetermined threshold value, the first opening value is changed to the second opening value by a predetermined change amount. Control the process of changing and
(F) Control is performed so that the (e) is performed once or more until the etching of the aluminum film is completed.
Board processing equipment.

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