JP2007048982A - Plasma treatment device and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of an order of supplying gas to generate plasma uniformly. <P>SOLUTION: The microwave plasma treatment device 100 propagates a microwave outputted from a microwave generator 28 from the slot of a slot antenna 23 to a plurality of sheets of dielectric parts through a plurality of wave guides 22 to irradiate the microwave into a treatment vessel 10 while penetrating respective dielectric parts. A controller 40 makes the incidence of the power of microwave into the treatment vessel 10 while supplying an Ar gas into the treatment vessel 10. After the plasma ignition of the Ar gas is effected by the power of the microwave, an SiH<SB>4</SB>gas and an NH<SB>3</SB>gas necessitating much more energy than that for obtaining the plasma Ar gas are supplied into the treatment vessel 10. By this operation, a microwave plasma treatment device 100 is capable of generating a good quality SiN film stably by obtaining the plasma of treatment gas by the power of the microwave introduced into the treatment vessel 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for controlling a plasma processing apparatus for plasma processing a target object such as a glass substrate. In particular, the present invention relates to a method for controlling the order in which gases are supplied.

  2. Description of the Related Art Conventionally, various plasma processing apparatuses have been developed for plasma processing a target object such as a glass substrate by converting a processing gas supplied into a processing container into plasma. Among these, the microwave plasma processing apparatus converts the processing gas into plasma by ionizing and dissociating the processing gas with the power of the microwave. In the plasma process, a mixed gas of an inert gas (or a monoatomic molecular gas) and a reactive gas (or a polyatomic molecular gas) is usually supplied into the processing vessel at the same time, and then microwaved. Is powered on.

  However, when the mixed gas is supplied in this way, electric field energy is insufficient at the time of plasma ignition, and plasma may be generated nonuniformly. On the other hand, in order to generate a uniform plasma while ensuring a sufficient plasma density, it is also conceivable to increase the microwave power or lengthen the microwave irradiation time.

However, when the microwave power is increased, the polyatomic molecular gas is dissociated too much, resulting in the inhibition of the formation of a high-quality film. For example, in the process of forming an amorphous silicon film, when SiH ₄ gas by the microwave which is slightly weakened dissociates to SiH ₃ radicals as precursor (precursor), dissociation degree not excessive dissociation to SiH ₂ radicals is desired , increasing the power of the microwave, the flow proceeds dissociation until SiH ₂ radicals, undesirably result in degrading the film by SiH ₂ radicals.

  Further, there are problems that the glass substrate is damaged by the microwave and the manufacturing cost is increased. Furthermore, the turnaround time required for plasma processing of the substrate becomes so long that it cannot be ignored, resulting in a problem that the efficiency of the entire processing is significantly reduced.

  On the other hand, the adverse effect of non-uniform plasma on glass substrate processing is, for example, in recent years when plasma processing is performed on glass substrates that have been increased in size to 730 mm × 920 mm or more, only wafers of about 300 mm × 300 mm are plasma processed. Compared to the conventional method, it is much larger.

  For example, in the case of a film forming process, in the case of a glass substrate having an area about 10 times as large as that of the wafer as described above, if plasma is generated non-uniformly by supplying a mixed gas almost simultaneously, the entire substrate is reduced. It is very difficult to produce such a high quality film quality.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a control method for a plasma processing apparatus and a plasma processing apparatus for controlling the order in which gases are supplied in order to generate plasma uniformly. It is to provide.

  In order to solve the above-described problems, according to an aspect of the present invention, there is provided a microwave plasma processing apparatus that plasma-processes an object to be processed by converting a processing gas into plasma by the power of a microwave incident into a processing container. In the control method, while supplying the first gas into the processing container, the microwave power is made incident into the processing container, and the first gas is ignited with plasma by the microwave power. There is provided a control method for a plasma processing apparatus, characterized in that a second gas that requires a larger energy to be converted into plasma than the first gas is supplied into the processing container.

  In the prior art in which microwave power is applied after the mixed gas of the first gas and the second gas is supplied into the processing container almost simultaneously, as described above, plasma is generated nonuniformly. There is a case. This is because there is a difference in consumption between the energy consumed in the process of converting the first gas into plasma and the energy consumed in the process of converting the second gas into plasma. In particular, the second gas requires molecular internal energy sufficient to cause dissociation, chemical reaction, and the like, and thus a large amount of microwave electric field energy is required in the process of turning into plasma.

For example, consider a case where the first gas is a monoatomic molecular gas and the second gas is a polyatomic molecular gas. In this case, in the process of converting the monoatomic molecular gas into plasma, energy is required only when ionizing. Therefore, in order to turn monoatomic molecular gas into plasma,
The monoatomic molecular gas only needs to include internal energy equivalent to the electron binding energy.

  On the other hand, in the process of converting a polyatomic gas into plasma, in addition to physical phenomena such as ionization, dissociation, and vibration excitation, a lot of energy is required for chemical phenomena such as chemical reactions with other gases. In general, the energy required for vibrational excitation and dissociation is smaller than the energy required for ionization, but in order to turn polyatomic molecular gas into plasma, it is more than the electronic bond energy (for example, the covalent bond is separated into the electronic bond energy). Therefore, the polyatomic molecular gas needs to include internal energy (equivalent to a value obtained by adding the binding energy).

  However, as described above, when the power of the microwave is increased, the polyatomic molecular gas is too dissociated, resulting in the inhibition of the formation of a high-quality film. Therefore, if a mixed gas of a monoatomic molecular gas and a polyatomic molecular gas is turned into plasma with the minimum required microwave power, the plasma is promoted in the case of a monoatomic molecular gas that does not require a large amount of energy. However, a polyatomic molecular gas that requires more energy for plasma formation than a monoatomic molecular gas is insufficient in energy to promote plasma formation, and as a result, plasma is generated nonuniformly.

  Considering this, the plasma processing apparatus of the present invention first supplies only the first gas to the processing container. As a result, until the plasma ignition that requires the most energy in the plasma generation process, only the first gas is rapidly turned into plasma by the electric field energy of the microwave. And after plasma ignition, the plasma processing apparatus of this invention supplies 2nd gas which requires larger energy in order to turn into plasma rather than 1st gas.

  In such a state, the second gas can be used as energy for converting the kinetic energy of electrons in the processing container into plasma in addition to the electric field energy of the microwave incident into the processing container. As a result, the second gas is rapidly turned into plasma by the electric field energy of the microwave and the kinetic energy of the electrons. As a result, uniform plasma can be stably generated.

  At this time, the timing of supplying the microwave power into the processing container may be the same as the time when the first gas is supplied or may be after that. Further, it may be determined whether or not the first gas is plasma-ignited by detecting a value corresponding to a wavelength of light generated when the gas is turned into plasma in the processing container.

  When the gas is ionized, the electrons generated by the ionization excite other molecules and generate ionization. When these molecules return to their original state (ground state), energy is released by light emission. Therefore, a value corresponding to the wavelength of the emitted light is detected, and when the value exceeds a certain threshold value, it is determined that plasma ignition. In addition, as a value according to the wavelength of light, the voltage detected by the photo sensor installed in the processing container is mentioned, for example.

  In addition, before the plasma ignition, the process conditions may be controlled so as to increase the collision frequency of electrons in the processing container or increase the internal energy of molecules. The process conditions may be pressure, temperature, microwave power, or light power.

  For example, if the pressure in the processing container is increased before the plasma ignition, the electron collision frequency can be increased by the increased pressure. Also, for example, if the temperature in the processing container is increased before plasma ignition, the electron movement becomes active, and the electron collision frequency can be increased.

  Also, for example, if the microwave power is increased before plasma ignition, the electron motion becomes active due to the electric field energy of the incident microwave, and the electron collision frequency can be increased. Also, irradiation with light having a short wavelength such as UV light or ultraviolet light before plasma ignition can increase the internal energy of the molecule due to the energy of the irradiated light and facilitate ionization.

  In this way, the plasma of the first gas is promoted by assisting energy by controlling at least one of pressure, temperature, microwave power, and light power. As a result, the time until plasma ignition can be shortened. As a result, the glass substrate is not easily damaged by the microwave, the manufacturing cost is reduced, and the turnaround time is shortened, so that the efficiency of the entire process can be significantly increased.

  The plasma processing apparatus may include a dielectric that propagates the microwave through the slot into the processing container, and the dielectric may be installed or formed so as to suppress the propagation of the surface wave of the microwave.

  Specifically, the dielectric may be formed of a plurality of dielectric parts. The dielectric part may be supported by a metal support member. The dielectric may have at least one of a concave portion or a convex portion formed on the surface of the dielectric through which the surface wave of the microwave propagates.

  According to the plasma processing apparatus having a dielectric formed in this manner, the surface wave of the microwave is prevented from propagating on the surface of the dielectric due to the dielectric parts, the metal support member, and the unevenness of the dielectric surface. be able to. Thereby, the generation of a standing wave can be prevented. As a result, it is possible to avoid the generation of non-uniform plasma due to standing waves.

  However, according to the plasma processing apparatus having the dielectric formed as described above, the energy of the surface wave is lost by preventing the surface wave from propagating. Due to this loss of energy, the gas tends to be difficult to ignite with plasma. However, according to the control method of the present invention, only the first gas is supplied first and the plasma is ignited, and then the second gas that requires more energy to be converted into plasma is supplied. Thereby, the plasma processing apparatus can be controlled so that uniform plasma is stably supplied. As a result, by forming the dielectric parts as described above, the above-described gas supply method further improves the advantage of the present apparatus that the plasma is generated uniformly by suppressing the generation of standing waves. , Plasma can be generated uniformly, and the object to be processed can be processed with high accuracy.

  According to another aspect of the present invention, there is provided a plasma processing apparatus for generating a microwave by plasma-treating an object to be processed by converting the processing gas into plasma by the power of the microwave incident into the processing container. The first gas supply means, the first gas supply means for supplying the first gas, and the first gas supplied by the generated microwave power, after the plasma ignition, the first gas There is provided a plasma processing apparatus comprising: a second gas supply unit that supplies a second gas that requires a larger amount of energy to be converted into plasma.

  According to this, based on the gas supply sequence determined in order to generate plasma uniformly, the plasma processing apparatus supplies gas in order into the processing container, so that uniform plasma can be stably generated. it can.

  Furthermore, according to another aspect of the present invention, a control program for controlling a plasma processing apparatus for plasma processing a target object by storing a processing gas into plasma by the power of the microwave incident into the processing container is stored. A computer-readable recording medium, wherein the first gas is supplied into the processing container while the first gas is supplied into the processing container, and the first gas is generated by the microwave power. A computer storing a control program for causing a computer to execute a process of supplying a second gas, which requires a larger energy than that of the first gas, into the processing container after the plasma is ignited by plasma. A readable recording medium is provided.

  According to this, it is possible to stably generate uniform plasma by causing a computer to execute a control program indicating the order in which gases are supplied in order to generate plasma uniformly.

  As described above, according to the present invention, it is possible to provide a method for controlling a plasma processing apparatus and a plasma processing apparatus for controlling the order of supplying gases in order to generate plasma uniformly.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

In this specification, 1 mTorr is (10 ⁻³ × 101325/760) Pa, and 1 sccm is (10 ⁻⁶ / 60) m ³ / sec.

(First embodiment)
(Configuration of microwave plasma processing equipment)
First, a microwave plasma processing apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a longitudinal sectional view of the microwave plasma processing apparatus 100 cut along a plane parallel to the x-axis direction and the z-axis direction. The microwave plasma processing apparatus 100 is an example of a plasma processing apparatus. In the present embodiment, a process for generating a silicon nitride film from Ar gas, SiH ₄ gas, and NH ₃ gas will be described as a processing process executed by the microwave plasma processing apparatus 100.

  The microwave plasma processing apparatus 100 has a casing composed of a processing container 10 and a lid 20. The processing container 10 has a bottomed rectangular parallelepiped shape with an open top and is grounded. The processing container 10 is made of a metal such as aluminum (Al).

  A susceptor 11, which is a mounting table on which an object to be processed such as a substrate W is mounted, is provided in the processing container 10 at approximately the center. The susceptor 11 is made of aluminum nitride, for example.

  Inside the susceptor 11, a power feeding unit 11a and a heater 11b are provided. A high frequency power supply 12b is connected to the power supply unit 11a via a matching unit 12a (for example, a capacitor). In addition, a high-voltage DC power supply 13b is connected to the power supply unit 11a via a coil 13a. The matching unit 12a, the high-frequency power source 12b, the coil 13a, and the high-voltage DC power source 13b are provided outside the processing vessel 10, and the high-frequency power source 12b and the high-voltage DC power source 13b are grounded.

  The power feeding unit 11a applies a predetermined bias voltage to the inside of the processing container 10 by the high frequency power output from the high frequency power source 12b. Further, the power feeding unit 11a electrostatically attracts the substrate W by a DC current output from the high-voltage DC power supply 13b.

  An AC power supply 14 provided outside the processing container 10 is connected to the heater 11b, and the substrate W is held at a predetermined temperature by an AC current output from the AC power supply 14.

  The bottom surface of the processing container 10 is opened in a cylindrical shape, and one end of the bellows 15 is mounted toward the outer wall surface of the processing container 10 in the vicinity of the opened outer periphery. A lifting plate 16 is fixed to the other end of the bellows 15. In this way, the opening at the bottom of the processing vessel 10 is sealed by the bellows 15 and the lifting plate 16.

  The susceptor 11 is supported by a cylindrical body 17 disposed on the lifting plate 16 and moves up and down integrally with the lifting plate 16 and the cylindrical body 17. Thereby, the susceptor 11 is adjusted to a height corresponding to the processing process.

  Around the susceptor 11, a baffle plate 18 is provided for controlling the gas flow in the processing container 10 to a preferable state. The inside of the processing container 10 is partitioned by a baffle plate 18 into a processing chamber 10 u on which the substrate W is placed and an exhaust chamber 10 u that communicates with an exhaust mechanism 19 provided in the lower part of the processing container 10.

The processing container 10 includes a dry pump 19a, an APC (Automatic Pressure Control) 19b, and a TMP (Turbo Molecular Pump: Turbo) as an exhaust mechanism 19.
Molecular Pump) 19c is provided. The dry pump 19a exhausts gas from the exhaust port 10a until the inside of the processing container 10 is in a predetermined reduced pressure state.

  The APC 19b is provided with a valve body that controls the communication state between the exhaust port 10b and the TMP 19c. The APC 19b slides the valve body of the APC 19b in a direction substantially parallel to the cross section of the exhaust port 10b in accordance with the change in the pressure P1 in the processing chamber 10u, so that the communication portion between the exhaust port 10b and the TMP 19c has a desired opening degree. It is supposed to be. As a result, the TMP 19c exhausts a gas having a flow rate proportional to the opening degree of the valve body of the APC 19b, and depressurizes the atmosphere in the processing container 10 to a predetermined degree of vacuum.

  The lid 20 is disposed so as to seal the upper part of the processing container 10. The lid 20 is formed of a metal such as aluminum (Al), for example, in the same manner as the processing container 10. The lid 20 is provided with a lid main body 21, waveguides 22a to 22f, slot antennas 23a to 23f, dielectrics 24a to 24f, and a support member 25.

  The processing container 10 and the lid body 20 are fixed so that airtightness is maintained by an O-ring 26 disposed between the lower surface outer peripheral portion of the lid main body 21 and the upper surface outer peripheral portion of the processing container 10. In addition, on the lower surface of the lid body 21, waveguides 22a to 22f are formed.

  As shown in FIG. 2 illustrating the inner wall surface of the ceiling portion of the processing container 10 facing the substrate W, the waveguides 22a to 22f are arranged in parallel to each other in the y-axis direction. Yes. A V-shaped branching waveguide 27a is connected to the waveguide 22a and the waveguide 22b in plan view at their ends. Similarly, the waveguide 22c and the waveguide 22d, and the waveguide 22e and the waveguide 22f are respectively provided with a V-shaped branching waveguide 27b and a branching waveguide 27c in plan view at their ends. It is connected. A microwave generator 28 is connected to each branch waveguide 27. The microwave generator 28 corresponds to microwave generation means for generating a microwave.

Each of the waveguides 22 and each of the branching waveguides 27 is formed by a rectangular waveguide whose cross section perpendicular to the axial direction is rectangular. For example, in the TE10 mode (TE wave: transverse electric wave), the long side tube wall of the cross section perpendicular to the axial direction of each waveguide 22 is parallel to the magnetic field. The tube wall in the short side direction becomes an E surface parallel to the electric field. The arrangement of the long side direction and the short side direction of each waveguide varies depending on the mode (electromagnetic field distribution in the waveguide). The inside of each waveguide 22 and each branch waveguide 27 is filled with, for example, alumina (aluminum oxide: Al ₂ O ₃ ), quartz, fluororesin, or the like.

  As shown in FIG. 1, the slot antenna 23a to the slot antenna 23f are provided below the waveguides 22a to 22f, respectively. Each slot antenna 23 is provided with a plurality of slots as through holes. For example, as shown in FIG. 2, the slot antenna 23a has six slots (slots 23a1 to 23a6). ing.

  The slot of each slot antenna 23 is formed in a long hole in plan view, and is provided such that the longitudinal direction thereof and the longitudinal direction of the waveguide 22 are substantially perpendicular. In addition, the slots are arranged at equal intervals, for example, λg / 2 (λg: wavelength in the waveguide). In this way, 36 (= 6 × 6) slots are evenly scattered throughout the inner wall surface of the ceiling of the processing container 10.

On the lower surface of the slot antenna 23, 36 dielectrics 24 having a substantially square flat plate shape are disposed for each slot. For example, tile-like dielectrics 24a1 to 24a6 are provided below the slots 23a1 to 23a6 provided in the slot antenna 23a, respectively. Each dielectric 24 is made of, for example, quartz glass, aluminum nitride (AlN), alumina (aluminum oxide: Al ₂ O ₃ ), sapphire, SiN, ceramics, or the like so as to transmit microwaves. The tile-shaped dielectric corresponds to dielectric parts.

  The support member 25 that supports each dielectric 24 crosses the seven elongated support bodies 25a1 to 25a7 and the support bodies 25b1 to 25b7 provided vertically and horizontally at predetermined intervals substantially vertically. Is formed in a lattice shape. The support member 25 is a conductor made of metal such as aluminum, and is grounded via the slot antenna 23, the lid body 21, and the processing container 10 shown in FIG. 1.

  The support member 25 supports each dielectric 24 so that each dielectric 24 is fitted in a substantially square opening provided in the support member 25. In this manner, the 36 dielectrics 24 are in a state in which the peripheral edge of the upper surface is in close contact with the lower surface of the slot antenna 23, and each dielectric 24 is provided by a substantially rectangular opening provided in the support member 25. In a state in which most of the lower wall surface is exposed toward the substrate W, it is arranged in a tile shape on the entire inner wall surface of the ceiling portion of the processing container 10.

  A plurality of gas introduction pipes 29 shown in FIG. 1 pass through the support members 25, and a large number of gas injection ports 30 (see FIG. 2) at the intersections of the support bodies 25a and the support bodies 25b. ) Is provided.

The processing gas supply source 31 includes a valve 31a1, a mass flow controller 31a2, a valve 31a3, an Ar gas supply source 31a4, a valve 31b1, a mass flow controller 31b2, a valve 31b3, a SiH ₄ gas supply source 31b4, a valve 31b5, a massflow controller 31b6, a valve 31b7, and and a NH ₃ gas supply source 31B8.

The processing gas supply source 31 selectively supplies each processing gas into the processing container 10 by controlling opening and closing of each valve. Each mass flow controller adjusts the processing gas to a desired concentration by controlling the flow rate of the processing gas supplied by each mass flow controller. The Ar gas supply source 31a4 corresponds to a first gas supply means for supplying a first gas (Ar gas). The SiH ₄ gas supply source 31b4 and the NH ₃ gas supply source 31b8 correspond to second gas supply means for supplying a second gas (SiH ₄ gas, NH ₃ gas).

Ar gas supplied from the Ar gas supply source 31a4 is injected from the gas injection port 30 into the processing container through the gas introduction pipe 29 connected to the gas flow path 32a. Further, NH ₃ gas, the gas injection port 30 through the gas introduction pipe 29 connected to the gas passage 32b which is supplied from the SiH ₄ gas and NH ₃ gas supply source 31b8 supplied from the SiH ₄ gas supply source 31b4 Is injected from.

  A cooling water supply source 33 is disposed outside the microwave plasma processing apparatus 100. The cooling water supply source 33 cools the inside of the lid main body 21 and the inside of the side wall of the processing container 10 by circulatingly supplying the cooling water to the water channel 34 provided inside the lid main body 21 and inside the side wall of the processing container 10. It is like that.

With such a configuration, the microwave plasma processing apparatus 100 propagates, for example, a 2,45 GHz microwave output from the microwave generator 28 to the slot antenna 23 through the plurality of waveguides 22, It propagates from a large number of slots to a plurality of dielectrics 24, passes through the dielectrics 24, and radiates into the processing vessel 10. The processing gas (Ar gas, SiH ₄ gas, NH ₃ gas) is turned into plasma by the electric field energy of the microwaves thus radiated. As a result, a silicon nitride film is generated on the substrate W.

(Configuration and operation of control device)
Next, the configuration and operation of the control device will be described. As shown in FIG. 3, in addition to the microwave generator 28, the processing gas supply source 31, and the cooling water supply source 33, a control device 40 and a UV light generation source 41 are provided outside the microwave plasma processing apparatus 100. Is provided. The control device 40 controls the microwave plasma processing apparatus 100. The UV light generation source 41 irradiates the microwave plasma processing apparatus 100 with the generated UV light. The microwave plasma processing apparatus 100 is provided with a pressure sensor 42 (a vacuum gauge such as a baratron or a convexron), a pressure sensor 43 (a vacuum gauge such as a baratron or a convexron), a temperature sensor 44 and a photosensor 45.

  The pressure sensor 42 detects the pressure P1 in the processing chamber 10u located above the susceptor 11 at predetermined time intervals. The pressure sensor 43 detects the pressure P2 in the exhaust chamber 10d located below the susceptor 11 at predetermined time intervals. The temperature sensor 44 detects the temperature T inside the side wall of the processing container 10 every predetermined time.

  The photosensor 45 detects the wavelength of light emitted when the gas is ionized or dissociated as a voltage F at predetermined time intervals. The photosensor 45 is an example of a photodetector that detects a value corresponding to the wavelength of light generated in the processing container. Other examples of the photodetector include a CCD and a spectroscope.

  The control device 40 is realized by, for example, a microcomputer including a ROM 40a, a RAM 40b, an interface 40c, and a CPU 40d. The ROM 40a stores a control program for controlling the timing for supplying gas and the timing for setting each process condition. The RAM 40b stores various parameters that predetermine process conditions.

  The interface 40c inputs sensor values P1, P2, T, and F detected by various sensors. The CPU 40d executes a control program stored in the ROM 40a on the basis of each sensor value input to the interface 40c and various parameters stored in the RAM 40b, so that the AC power supply 14, the APC 19b, the microwave are generated at a predetermined timing. Control signals are output to the generator 28, the processing gas supply source 31, the cooling water supply source 33, and the UV light generation source 41, respectively.

  Next, the operation of the control device 40 will be described with reference to FIGS. FIG. 4 is a flowchart showing a gas supply processing routine (control program) executed by the control device 40 to control a gas supply sequence. FIG. 5 is a time chart showing the timing for controlling each parameter.

  The control device 40 starts processing from step 400 in FIG. 4 and outputs a control signal to the processing gas supply source 31 in step 405 (see FIG. 3). When this control signal is input, the processing gas supply source 31 supplies, for example, 1000 sccm of Ar gas into the processing container 10 (time t0 in FIG. 5).

  Next, the control device 40 inputs the pressure value P1 detected by the pressure sensor 42 in step 410, the pressure value P1 input in step 415, and a predetermined ideal pressure value (for example, 250 mTorr). A control signal indicating the difference value is output to the APC 19b. When this control signal is input, the APC 19b decreases the opening of the valve body so as to increase the pressure in the processing container 10 to 250 mTorr, and decreases the flow rate of the gas exhausted from the TMP 19c (time t1 in FIG. 5). ).

  Next, the control device 40 outputs a control signal to the microwave generator 28 in step 420. When this control signal is input, the microwave generator 28 turns on the power and inputs 2.5 kW × 6 (6 is the number of waveguides) microwaves (time t2 in FIG. 5).

  Next, the control device 40 inputs the voltage F detected by the photosensor 45 in step 425, and proceeds to step 430 to determine whether or not the plasma is ignited under all the dielectric parts. If the detected voltage F has not reached the given threshold value, the control device 40 proceeds to step 435 to determine whether or not the time is over. If not, the control device 40 returns to step 425 and within a predetermined time. Steps 425 to 435 are repeated until plasma ignition occurs at the bottom of all dielectric parts.

When the plasma is ignited below all the dielectric parts, the control device 40 proceeds to step 440 following step 430 and outputs a control signal to the processing gas supply source 31. When this control signal is input, the gas supply source 31 supplies, for example, 200 sccm of SiH ₄ gas and 800 sccm of NH ₃ gas into the processing vessel 10 (time t3 in FIG. 5). Generated. The time t0 to the time t3 may be within 10 seconds. However, in consideration of substrate damage and turnaround time due to microwaves, 5 sec or less is preferable.

  Thereafter, in step 445, the control device 40 outputs a control signal for stopping the supply of the processing gas, a control signal for stopping the pressure control, and a control signal for turning off the microwave power source. Each is output to each device (time t4 in FIG. 5), and the process proceeds to step 495 to end the processing of this routine.

  According to this, the control device 40 controls the microwave plasma processing apparatus 100 based on the above processing procedure, so that uniform plasma can be stably generated. Here, the reason why the control apparatus 40 can stably generate uniform plasma by controlling the microwave plasma processing apparatus 100 based on this processing procedure will be specifically described.

  A monoatomic molecular gas such as Ar gas is ionized by the electric field energy of microwaves but is not dissociated. In other words, in the process of converting the monoatomic molecular gas into plasma, the electric field energy of the microwave is consumed only when the monoatomic molecular gas is ionized. As a result, the monoatomic molecular gas supplied into the processing vessel is ionized one after another while sequentially consuming the microwave electric field energy, and as a result, uniform plasma is stably generated from the sequentially supplied Ar gas. be able to.

On the other hand, in the process of converting polyatomic gas such as SiH ₄ gas and NH ₃ gas into plasma, in addition to the physical phenomenon of ionization and dissociation, much energy is required for the chemical phenomenon of chemical reaction with other gases. Become. In general, the energy required for vibrational excitation and dissociation is smaller than the energy required for ionization. However, in order to convert polyatomic gas into a plasma, the energy is higher than the electron binding energy (for example, the chemical energy for the electron binding energy required for ionization). The polyatomic gas must contain internal energy (equivalent to the sum of bond energies for breaking bonds between bonds).

  However, as described above, when the power of the microwave is increased, the polyatomic molecular gas is too dissociated, resulting in the inhibition of the formation of a high-quality film. Therefore, if a mixed gas of a monoatomic molecular gas and a polyatomic molecular gas is turned into plasma with the minimum required microwave power, the plasma is promoted in the case of a monoatomic molecular gas that does not require a large amount of energy. However, in a polyatomic molecular gas that requires more energy for plasma than a monoatomic molecular gas, there are parts that dissociate (ionize) and parts that do not dissociate due to insufficient energy, and the plasma is generated unevenly as a whole. .

  From the above, it is easier to turn the gas into a plasma under the situation where only the monoatomic molecular gas and the polyatomic molecular gas are mixed, that is, under the situation where only the monoatomic molecular gas exists, It can be seen that the plasma spreads more easily.

  On the other hand, in the process of turning a gas into plasma, energy is required most at the time of plasma ignition. Therefore, once the plasma of the monoatomic molecular gas is ignited and the plasma spreads in the processing container, less energy is required to maintain the plasma. Therefore, if the polyatomic molecular gas is introduced into the processing container after the plasma ignition, the polyatomic molecular gas can be smoothly turned into plasma and a uniform plasma state can be maintained.

Therefore, the microwave plasma processing apparatus 100 of the present embodiment first supplies Ar gas, ignites the Ar gas with a microwave power, and then supplies SiH ₄ gas and NH ₃ gas, whereby Ar gas is supplied. Then, SiH ₄ gas and NH ₃ gas introduced thereafter are stably converted to plasma with the minimum microwave power necessary to ignite the plasma.

  Such a gas supply method is particularly effective for the microwave plasma processing apparatus 100 having a plurality of dielectric parts as described above. For the reason, the plasma states in the vicinity of dielectrics of the microwave plasma processing apparatus (SWP: Surface Wave Plasma) shown in FIG. 6 and the microwave plasma processing apparatus 100 (CMEP: Cellular Microwave Excitation Plasma) according to the present embodiment are compared. While explaining. SWP is an example of a microwave plasma processing apparatus that does not suppress the propagation of surface waves, and CMEP is an example of a microwave plasma processing apparatus that suppresses the propagation of surface waves. For convenience of explanation, the plasma generated in the entire SWP dielectric is referred to as plasma P, and the plasma generated under the dielectric parts 24a1, 24b1, 24c1, and 24d1 surrounded by the CMEP beams. Are plasmas P1, P2, P3, and P4, respectively.

  First, the plasma state of SWP will be described. When gas is supplied to the SWP and the electric field energy of the microwave exceeds a certain threshold, the gas is ionized and plasma ignition occurs. Then, in SWP, the plasma spreads over the entire lower surface of the dielectric due to the surface wave propagating on the lower wall surface of the dielectric, and uniform plasma P is generated. As a result, in the SWP, the plasma P is generated in a stable state in almost the same manner when the mixed gas is supplied or when only the Ar gas is supplied. However, in SWP, a surface wave propagates on the lower surface of the dielectric, and a standing wave is generated by interference between the traveling wave and the reflected wave reflected at the end of the processing container. Thus, the amplitude of the standing wave generated between the dielectric and the plasma is increased by the interference between the reflected wave and the traveling wave. For this reason, the electric field energy varies between the antinodes and nodes of the standing wave, and the plasma P becomes non-uniform due to the difference in electric field energy density. In addition, the standing wave generated in this manner causes a portion having a high electric field energy density to move in the processing vessel, thereby causing the plasma P to become unstable, and the concentration of the plasma P and mode jumping occur due to pressure dependence.

  On the other hand, in CMEP, since the dielectric is formed by a plurality of dielectric parts, the surface wave generated by the electric field energy coming out of the slot is supported by a metal beam (support) between the dielectric parts. After propagating to the member, it is reflected by the beam. The standing wave generated by the interference between the reflected wave and the traveling wave propagates only within the beam. Here, the length of the dielectric part in the longitudinal direction is about 188 mm, whereas the wavelength of the microwave in vacuum is 120 mm. Therefore, each standing wave generated on the lower surface of the dielectric part is about 1.5 wavelengths. For this reason, in CMEP, the degree of interference between the reflected wave and the traveling wave is smaller than that of SWP, and furthermore, when the surface wave reflects off the beam, a loss occurs in the energy. Is smaller than SWP. Therefore, in the case of CMEP, as compared with the case of SWP, even when a standing wave is generated, there is less variation in electric field energy, and the plasma can be maintained in a stable state.

  However, the plasma ignition point exists in each dielectric part surrounded by each beam in CMEP, and the threshold value of each ignition point is different. That is, in CMEP, there are a portion that ignites and a portion that does not ignite due to a difference in threshold level. This difference in the threshold level of the ignition point may be caused by, for example, a subtle difference in the intensity of microwave energy incident from the slots of each dielectric part, the mixing amount and mixing ratio of the mixed gas, etc. . Therefore, “plasma ignition” in CMEP means a state in which plasma is ignited at all ignition points. In particular, when mixed gas is introduced as compared with the case where only Ar gas is introduced, as described above, ionization, dissociation, vibration excitation, and chemical reactions such as breaking of covalent bonds between molecules are performed. Since internal energy is required, the electric field energy consumed is very large. However, in order to produce a good quality film, it is necessary to inject the minimum necessary microwave power. With such weak energy, the threshold level of the ignition point of each part partitioned by each beam is low. The difference has a subtle effect on the plasma ignition. As a result, there are places where the plasma is ignited (plasma P2, P4: see the mixed gas supply in FIG. 6) and places where the plasma is not ignited (plasma P1, P3).

  Therefore, according to the gas ignition sequence described above, when only Ar gas is first supplied to CMEP, the electric field energy is consumed only for the Ar gas plasma, so all dielectric parts are used even if the electric field energy is weak. The plasma is ignited to generate plasmas P1 to P4 (see Ar gas supply in FIG. 6). As described above, in the CMEP, once the plasmas P1 to P4 are generated on the lower surface of each dielectric part, the plasmas P1 to P4 can be held in a stable state.

Based on the characteristics of the microwave plasma processing apparatus 100 according to the present embodiment described above, the inventor determines the order in which the gas is supplied using the control device 40 as Ar gas supply → microwave input → SiH ₄ gas, NH. ₃ is controlled to the order of the gas supply, and observe the state of the plasma generated in the microwave plasma processing apparatus 100 at that time. The experimental results are shown in FIG.

(Experimental result)
FIG. 7A shows the plasma observation result when the mixed gas is supplied to the microwave plasma processing apparatus 100 by the conventional method. FIG. 7B shows a plasma observation result when a gas is supplied to the microwave plasma processing apparatus 100 based on the above sequence.

As shown in each table, the inventor has four kinds of pressures (226 mT, 400 mT, 600 mT, 800 mT) shown in the vertical column and four kinds of microwave powers (4. 3 kW, 3.4 kW, 2.3 kW, and 1.7 kW) were tested in detail. Of the four cells corresponding to each case shown in each table, the upper left cell (A) indicates the uniform / non-uniform state of the plasma after the Ar gas is supplied. The upper right cell (B) shows a uniform / non-uniform state of plasma when a mixed gas of Ar gas, SiH ₄ gas and NH ₃ gas is supplied (silicon nitride film generation process). The lower left cell (C) shows the uniform / non-uniform state of plasma when Ar gas, SiH ₄ gas and H ₂ gas are supplied (amorphous silicon production process).

  According to this, the plasma generated under the condition (A) was uniform in the longitudinal direction under almost all conditions. However, the plasma generated in the case of (B) was non-uniform in the longitudinal direction under almost all conditions. In this case, the amorphous silicon generation process is not evaluated.

  However, based on the above-described sequence found by the inventor (ignition of Ar gas (monoatomic molecular gas) at 600 mTorr → pressure adjustment in the process of turning Ar gas into plasma → introducing real gas (polyatomic molecular gas)). When the plasma processing apparatus 100 is controlled (in the case of FIG. 7B), the plasma generated under the conditions of (A), (B), and (C) has a high pressure and a low microwave power. Except for this, it was uniform in the longitudinal direction under almost all conditions. As a result, the inventor is a very effective means for stably generating a uniform plasma controlled by the sequence found by the inventor in the microwave plasma processing apparatus 100 having a plurality of dielectric parts. I was able to confirm that there was.

  In this way, a new idea has been made by the inventor, and the idea has been realized through daily efforts. As a result, the plasma generated uniformly and stably has become very large in recent years as the display size has increased. This is especially beneficial when plasma-treating a glass substrate that has been transformed, and the results are much greater than before. The inventors who have achieved a certain result in this way have found a further improvement for promoting plasma ignition. The improvement will be described in the second embodiment below.

(Second Embodiment)
The control device 40 according to the second embodiment does not perform such control in that the condition of the process is controlled so as to increase the collision frequency of electrons in the processing container and the internal energy stored in the molecule. Operation is different from the control device 40 according to the embodiment. Therefore, the operation of the control device 40 of the present embodiment will be described with reference to FIGS. 8 and 9 focusing on this difference. The configuration of the microwave plasma processing apparatus 100 controlled by the control apparatus 40 is the same.

(Operation of control device)
FIG. 8 is a flowchart showing a gas supply processing routine (control program) according to the present embodiment. FIG. 9 is a time chart showing the timing for controlling each parameter.

  The control device 40 starts processing from step 800 in FIG. 8 and executes the processing from step 405 to step 420 as in the first embodiment, and performs the processing from step 425 to step 435 until plasma ignition occurs. repeat. However, in step 415, a control signal for controlling the inside of the processing vessel to a pressure higher than the pressure controlled in step 415 of the first embodiment is output.

When plasma is ignited at the lower part of all dielectric parts, the control device 40 outputs a control signal for lowering the pressure in Step 805 (time t2 ′ in FIG. 9), and SiH ₄ gas and NH ₃ gas at time t3. And a control signal for stopping the supply of processing gas, pressure control, and microwave supply at time t4, and the process proceeds to step 895. The routine processing ends. Time t1 to time t2 ′ is preferably within 10 seconds, and time t1 to time t2 and time t2 to time t2 ′ are preferably within 5 seconds. However, in consideration of the turnaround time and the like, it is preferably within 5 seconds.

  According to this, it is possible to increase the collision frequency of electrons by increasing the pressure in the processing container before plasma ignition, and to promote plasma ignition of Ar gas. By shortening the time to plasma ignition in this way, the microwave irradiation time is shortened to prevent damage to the glass substrate, and the turnaround time is shortened to increase the efficiency of the entire process. Can be improved.

  In the above description, the control device 40 increases the collision frequency of electrons in the processing container by controlling the pressure in multiple stages. However, the control device 40 may control at least one of the process conditions such as temperature, microwave power, or light power. Specifically, the control device 40 controls at least one of the temperature, the microwave power, and the light power so that the value before the plasma ignition becomes larger than the value after the plasma ignition. May be.

  For example, before the plasma is ignited, the electron motion may be activated by increasing the temperature to increase the electron collision frequency. Actually, by sending a control signal to a temperature controller (not shown) that controls the cooling water supply source 33 in FIG. 3, the cooling water supply source 33 moves to the inside of the wall surface of the processing vessel 10 and the vicinity of the waveguide 22 of the lid body. The temperature of the supplied refrigerant may be controlled. Alternatively, the heater 11b may be controlled to a desired temperature by an AC current output from the AC power supply 14 by sending a control signal to the AC power supply 14.

  Further, for example, before the plasma is ignited, the electron motion may be activated by increasing the power of the microwave to increase the electron collision frequency. Actually, the movement of electrons can be activated by sending a control signal for increasing the power of the microwave to the microwave generator 28.

  Further, for example, before plasma ignition, the internal energy of the molecule may be increased by irradiating light with a short wavelength such as UV light or ultraviolet light (that is, with energy assist). Actually, by sending a control signal to the UV light source 41, the UV light can be emitted from the UV light source 41 to increase the internal energy of the molecule.

Note that the control device 40 is configured to adjust the pressure, temperature, microwave power, or light intensity after plasma ignition and before the SiH ₄ gas and the NH ₃ gas are supplied in order to make the parameters match the process conditions. The power needs to be reduced to a value that meets the process conditions.

  As described above, the microwave plasma processing apparatus 100 according to the present embodiment is formed so as to suppress the propagation of surface waves on the surface of the dielectric by a plurality of dielectric parts. According to the microwave plasma processing apparatus 100 configured as described above, generation of a standing wave formed by reflection of the surface wave can be suppressed by suppressing the propagation of the surface wave.

  Then, based on the above-described sequence that matches the characteristics of the microwave plasma processing apparatus 100, the processing gas is supplied in the order of monoatomic molecular gas and polyatomic molecular gas in order, and various parameters (pressure, temperature, Set wave power, optical power, etc.) in a timely manner according to the process conditions. As a result, uniform plasma can be stably generated, and the substrate W can be accurately subjected to plasma processing.

Note that the gas species supplied as the first gas by the sequence described above is not limited to Ar gas, and may be, for example, a monoatomic molecular gas such as He gas or Xe gas. Further, the gas species supplied as the second gas that requires more energy to be converted into plasma than the first gas is not limited to SiH ₄ gas and NH ₃ gas, and for example, hydrogen gas (H ₂ ) A polyatomic molecular gas such as

  Further, the pressure controlled by the control device 40 from time t1 to time t4 may be any value as long as it is in the range of 60 mTorr to 1000 mTorr. Note that the upper limit is set for the pressure value to be controlled because it is necessary to lower the pressure to a predetermined process condition value by time t3 when the polyatomic molecular gas is supplied and the plasma processing is started.

Also, among the processing gas supplied from the processing gas supply source 31 into the processing chamber, the flow rate of Ar gas 400~3000sccm, SiH ₄ gas flow rate is 50 to 500 sccm, NH ₃ gas flow rate in the range of 400~2000sccm If it is. Moreover, the power density of the microwave thrown in in a processing container should just be the range of 1.0-7.5 w / cm < ² >. Furthermore, the temperature in the processing container 10 should just be hold | maintained in the range of 50-150 degreeC. The size of the glass substrate may be 730 mm × 920 mm or more, for example, G4.5 substrate size is 730 mm × 920 mm (chamber diameter: 1000 mm × 1190 mm), G5 substrate size is 1100 mm × 1300 mm (chamber diameter: 1470 mm × 1590 mm).

  In order to detect the pressure in the processing container, it is preferable to use the pressure sensor 42 provided in the processing chamber 10u, but the pressure sensor 43 provided in the exhaust chamber 10d may be used.

  Further, the control device 40 may be configured by hardware or software.

  In the above embodiment, the operations of the respective units are related to each other, and can be replaced as a series of operations in consideration of the relationship between each other. And by replacing in this way, the embodiment of the invention of the plasma processing apparatus can be made an embodiment of a method for controlling the plasma processing apparatus.

  Further, by replacing the operation of each unit with the processing of each unit, a program embodiment can be obtained. Further, by storing the program in a computer-readable recording medium in which the program is recorded, the embodiment of the program can be an embodiment of a computer-readable recording medium in which the program is recorded.

  Therefore, an embodiment of a control method for controlling a plasma processing apparatus is a control program for controlling a plasma processing apparatus that performs plasma processing on an object to be processed by converting the processing gas into plasma by the power of the microwave incident into the processing container. Then, after supplying the first gas into the processing container and making the microwave power enter the processing container, and after the first gas is plasma ignited by the microwave power, An embodiment of a control program that causes a computer to execute a process of supplying a second gas, which requires a larger energy than that of the first gas, into the processing container, which requires more energy than the first gas. In this case, the control program to be executed by the computer may be stored in the ROM 40a or the like of FIG. 3, or may be imported via a network (not shown) using a communication means (external interface) provided in the control device 40. Good.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the plasma processing apparatus according to the present invention may be a microwave plasma processing apparatus having a plurality of tile-shaped dielectric parts, and a concave or convex portion is formed on the surface of the dielectric through which the surface wave of the microwave propagates. A microwave plasma processing apparatus in which at least one of the above is formed may be used.

  The plasma processing executed by the plasma processing apparatus according to the present invention is not limited to the CVD processing, and any plasma processing such as ashing processing and etching processing is possible.

  The present invention relates to a plasma processing apparatus control method for controlling the order of gas supply in order to generate plasma uniformly, a plasma processing apparatus control apparatus, and a computer readable program storing a control program for controlling the plasma processing apparatus Applicable to various recording media.

It is a longitudinal cross-sectional view of the microwave plasma processing apparatus concerning 1st Embodiment of this invention. It is explanatory drawing for demonstrating the ceiling inner wall surface of the processing container concerning the embodiment. It is description for demonstrating the flow of the control signal input / output between a control apparatus and a microwave plasma processing apparatus. It is the flowchart which showed the gas supply process routine which CPU of a control apparatus performs in the same embodiment. It is a time chart of each parameter concerning the embodiment. It is explanatory drawing for demonstrating the process of the plasma generation of SWP and CMEP. FIG. 7A is a diagram showing a plasma observation result when supplying a mixed gas, and FIG. 7B is a diagram showing a plasma observation result when supplying gas based on a gas supply sequence. It is the flowchart which showed the gas supply process routine which CPU of a control apparatus performs in 2nd Embodiment of this invention. It is a time chart of each parameter concerning the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Processing container 11 Susceptor 18 Baffle plate 19a Dry pump 19b APC (automatic pressure regulator)
19c TMP (turbomolecular pump)
28 Microwave generator 29 Gas introduction pipe 30 Gas injection port 31 Process gas supply source 31a4 Ar gas supply source 31b4 SiH ₄ gas supply source 31b8 NH ₃ gas supply source 33 Cooling water supply source 40 Control device 41 UV light generation source 42 Pressure Sensor 43 Pressure sensor 44 Temperature sensor 45 Photo sensor 100 Microwave plasma processing apparatus

Claims (12)

A method for controlling a plasma processing apparatus that plasma-processes an object to be processed by converting the processing gas into plasma by the power of the microwave incident in the processing container:
While supplying the first gas into the processing container, microwave power is incident on the processing container;
After the first gas is ignited with plasma by the power of the microwave, a second gas that requires more energy to be converted into plasma than the first gas is supplied into the processing container. A method for controlling a plasma processing apparatus.   The method for controlling a plasma processing apparatus according to claim 1, further comprising: controlling process conditions so as to increase an electron collision frequency in the processing container before plasma ignition.   3. The method of controlling a plasma processing apparatus according to claim 2, wherein the process condition is at least one of pressure, temperature, microwave power, and light power. The plasma processing apparatus includes:
A dielectric for propagating the microwave through the slot and into the processing vessel;
The dielectric is
4. The method for controlling a plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is installed or formed so as to suppress propagation of surface waves of microwaves. The dielectric is
The method for controlling a plasma processing apparatus according to claim 4, wherein the plasma processing apparatus is formed of a plurality of dielectric parts. The dielectric parts are:
6. The method for controlling a plasma processing apparatus according to claim 5, wherein the plasma processing apparatus is supported by a metal support member. The dielectric is
The method for controlling a plasma processing apparatus according to claim 4, wherein at least one of a concave portion and a convex portion is formed on a surface of the dielectric material on which the surface wave of the microwave propagates.   The method for controlling a plasma processing apparatus according to claim 1, wherein the first gas is a monoatomic molecular gas.   The method for controlling a plasma processing apparatus according to claim 1, wherein the second gas is a polyatomic molecular gas.   2. It is determined whether or not the first gas has been ignited with plasma by detecting a value corresponding to a wavelength of light generated when the gas is turned into plasma in the processing container. The control method of the plasma processing apparatus described in any one of -9. A plasma processing apparatus that plasma-processes an object to be processed by converting a processing gas into plasma by the power of a microwave incident into a processing container:
Microwave generation means for generating microwaves;
First gas supply means for supplying a first gas;
After the supplied first gas is ignited with plasma by the generated microwave power, a second gas is supplied that requires a larger energy to be converted into plasma than the first gas. A plasma processing apparatus comprising: a gas supply means; A computer-readable recording medium storing a control program for use in a plasma processing apparatus for plasma processing a target object by converting a processing gas into plasma by the power of microwaves incident into the processing container:
A process of causing the microwave power to enter the processing container while supplying the first gas into the processing container;
After the first gas is ignited with plasma by the power of the microwave, a process of supplying a second gas, which requires a larger energy than the first gas, into the processing container; The computer-readable recording medium which memorize | stored the control program which makes a computer perform.

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