JP2014039060A - Plasma processing device, plasma processing method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing device capable of removing a polymer from an electrode insulated electrically.SOLUTION: A plasma processing device 10 comprises: a substrate processing chamber 11 having a processing space S; a susceptor 12 arranged in the substrate processing chamber 11 and connected with a high frequency power source 20 or the like; an upper electrode plate 38 having a lower surface exposed to the processing space S and insulated electrically from a wall part of the substrate processing chamber 11 and the susceptor 12; a direct current source 49 connected with the upper electrode plate 38; and a control part 52. The control part 52 determines a value of negative direct current voltage to be applied to the upper electrode plate 38 according to a processing condition of RIE processing to be performed.

Description

  The present invention relates to a plasma processing apparatus, a plasma processing method, and a storage medium, and particularly to a plasma processing apparatus having an electrode that is electrically insulated from other components.

  A substrate processing chamber having a processing space into which a wafer as a substrate is carried, a lower electrode disposed in the substrate processing chamber and connected to a high frequency power source, and an upper electrode disposed to face the lower electrode A parallel plate type plasma processing apparatus is known. In this plasma processing apparatus, a processing gas is introduced into the processing space, and the upper electrode and the lower electrode apply high frequency power to the processing space. Further, when the wafer is carried into the processing space and placed on the lower electrode, the introduced processing gas is converted into plasma by high-frequency power to generate ions and the like, and the wafer is subjected to plasma processing, for example, etching. Apply processing.

  When a CF-based processing gas is introduced into the processing space as a processing gas to form a plasma, CF-based reaction products are generated in the processing space, and as a polymer on the surfaces of the upper and lower electrodes and the inner wall surface of the substrate processing chamber. Adhere to. Here, since high frequency power is supplied to the upper electrode and the lower electrode, the potentials of the surfaces of the upper electrode and the lower electrode fluctuate, and there is a potential difference between the plasma in the processing space and the surfaces of the upper electrode and the lower electrode. Occur. According to this potential difference, ions collide with the surfaces of the upper electrode and the lower electrode, and the polymer attached to the surfaces is removed. In general, since the wall of the substrate processing chamber is grounded, a potential difference is generated between the plasma in the processing space and the inner wall surface of the substrate processing chamber. Therefore, the polymer adhering to the inner wall surface is also removed by ion collision.

  There is also known a plasma processing apparatus in which a dust collecting electrode is disposed in the processing space in order to reliably prevent the polymer from adhering to the surfaces of the upper and lower electrodes and the inner wall surface of the substrate processing chamber. In this plasma processing apparatus, a DC voltage is applied to the dust collection electrode, and the dust collection electrode attracts and captures a reaction product in the processing space by electrostatic force (see, for example, Patent Document 1).

  In recent years, with the high integration of semiconductor devices, the pattern formed on the wafer has been miniaturized. Miniaturization of semiconductor devices has been realized by shortening the light source wavelength of an exposure apparatus used for photolithography, and currently, an argon fluoride (ArF) excimer laser having a wavelength of 0.193 μm is used as the light source. Has reached.

  Photoresist films (ArF resist films) used for photolithography using an ArF excimer laser have insufficient etching selectivity with respect to the constituent materials of semiconductor elements. Therefore, etching is performed on the constituent materials using a single layer of the ArF resist film as a mask. It is difficult to apply accurately.

  Further, as the pattern becomes finer, the photoresist film cannot be formed thick, and a high etching selectivity with respect to the constituent material of the semiconductor element is required. However, it is difficult to realize the high etching selectivity.

  Therefore, a multilayer resist process has been developed as an example of a process for solving these problems. The multi-layer resist process is a process in which the resist is made into a multi-layer and the target layer is precisely processed in order to enhance the function of the constituent material as an etching mask material.

The multilayer resist process is described in Patent Document 2, for example. Hereinafter, the multilayer resist process described in Patent Document 2 will be briefly described.

First, on a constituent material of a semiconductor element (silicon oxide film-based insulating film, for example, SiO ₂ ), a lower resist film (coating carbon film, for example, amorphous carbon) having etching selectivity with respect to the constituent material, and a lower layer An oxide film (SOG film such as SiO ₂ or SiOC) having etching selectivity with respect to the resist film and a photoresist film are sequentially formed.

  Next, after patterning the photoresist film by photolithography, the oxide film (inorganic film) is etched using the photoresist film as a mask, and the pattern of the photoresist film is transferred to the oxide film. Next, the lower resist film (organic film) is etched using the patterned oxide film as a mask, and the pattern of the oxide film is transferred to the lower resist film. Then, the constituent material (inorganic film) is processed using the lower resist film as a mask.

Here, in the insulating film etching apparatus, from the viewpoint of efficiency, a silicon oxide-based insulating film, for example, an inorganic film etching of a silicon-based material such as SiO ₂ and a coating-type carbon film such as an amorphous carbon-based carbon base Both organic film etching of the same material is required in the same chamber. For etching SiO ₂ -based materials, CF-based gas typified by C ₄ F ₈ is mainly used, and in order to achieve a high etching rate, an etching apparatus capable of realizing high electron density and high bias etching is required. Is done. On the other hand, when etching an organic film, a gas containing no F such as O ₂ , CO, N ₂ , H ₂ is used, and an etching apparatus capable of realizing high electron density and low bias etching is required.

JP-A-7-106307 JP 2002-093778 A

  Incidentally, in recent years, in order to control the plasma in the processing space to a desired state, a plasma processing apparatus that does not supply high-frequency power to the upper electrode has been developed. In this plasma processing apparatus, since the upper electrode is electrically insulated from the wall portion of the substrate processing chamber, the high frequency power supplied to the lower electrode may be supplied to the upper electrode through the grounded wall portion. Absent. In addition, the upper electrode receives charge from the plasma, but the charge does not flow away from the upper electrode, so the upper electrode is charged up, and the potential difference between the surface of the upper electrode and the plasma in the processing space is reduced. Accordingly, the energy of ions that collide with the surface of the upper electrode is reduced, and the polymer attached to the surface is not removed.

  If the polymer adhering to the surface of the upper electrode is not removed, the polymer peels off and becomes particles and adheres to the surface of the wafer, causing problems such as deterioration in the yield of semiconductor devices manufactured from the wafer.

  In addition, in the case of using an apparatus that has a silicon-based upper electrode and applies high-frequency power to the processing space from the upper electrode and the lower electrode as an etching apparatus that performs the above-described multilayer resist process, in the inorganic film processing, It is known that when an electrode is sputtered, a high selectivity can be realized with respect to a photoresist that is a mask film, even if high electron density plasma is used. On the other hand, in the organic film processing, when high frequency power is applied to the upper electrode, there arises a problem that the silicon-based upper electrode material jumps out by sputtering and deposits on the wafer. Since the processing gas supplied to the processing space in the organic film processing is a gas not containing F, the silicon-based material deposited on the wafer cannot be removed, and these are deposited as residues.

When a device that applies high-frequency power only from the lower electrode is used, the above-mentioned problems do not occur. However, in the inorganic film processing, since the effect of sputtering of the silicon-based upper electrode cannot be obtained, plasma with a high electron density is used. In such a case, there arises a problem that the photoresist selectivity is lowered.

  An object of the present invention is to provide a plasma processing apparatus, a plasma processing method, and a storage medium capable of performing a continuous process of inorganic film processing and organic film processing on a substrate.

  In order to achieve the above object, a plasma processing apparatus of the present invention has a processing space into which a substrate is carried, and is disposed in the substrate processing chamber for performing plasma processing on the substrate in the processing space. And a first electrode connected to a high-frequency power source, and a second electrode having an exposed portion exposed to the processing space and electrically insulated from the substrate processing chamber and the first electrode. In the plasma processing apparatus, an inorganic film and an organic film are formed on the substrate, and the exposed portion is made of a silicon-based material, and when the inorganic film on the substrate is subjected to plasma processing, The potential difference between the generated plasma and the second electrode is set to a value at which the exposed portion of the second electrode is sputtered by the plasma, and the organic film of the substrate is subjected to plasma treatment. , A potential difference of the plasma and the second electrode, the exposed portions included in the second electrode and sets the value not be sputtered by the plasma.

  In order to achieve the above object, a plasma processing method of the present invention has a processing space into which a substrate is loaded, and a substrate processing chamber for performing plasma processing on the substrate in the processing space, and a substrate processing chamber. And a first electrode connected to a high-frequency power source, and a second electrode having an exposed portion exposed to the processing space and electrically insulated from the substrate processing chamber and the first electrode. A plasma processing method in a plasma processing apparatus, wherein an inorganic film and an organic film are formed on the substrate, the exposed portion is made of a silicon-based material, and the inorganic film processing is performed on the inorganic film on the substrate. And an organic film processing step for performing a plasma treatment on the organic film of the substrate. In the inorganic film processing step, the plasma generated in the processing space and the electric power of the second electrode The difference is set to a value at which the exposed portion of the second electrode is sputtered by the plasma, and in the organic film processing step, the second electrode has a potential difference between the plasma and the second electrode. The exposed portion is set to a value that is not sputtered by the plasma.

  In order to achieve the above object, a storage medium of the present invention has a processing space into which a substrate is carried, a substrate processing chamber for performing plasma processing on the substrate in the processing space, a substrate processing chamber disposed in the substrate processing chamber, and Plasma comprising a first electrode connected to a high-frequency power source and a second electrode having an exposed portion exposed to the processing space and electrically insulated from the substrate processing chamber and the first electrode. A computer-readable storage medium storing a program for causing a computer to execute a plasma processing method in a processing apparatus, wherein the substrate is formed with an inorganic film and an organic film, and the exposed portion is made of a silicon-based material. The plasma processing method includes an inorganic film processing step of performing plasma processing on the inorganic film of the substrate, and an organic film processing step of performing plasma processing on the organic film of the substrate. In the inorganic film processing step, the potential difference between the plasma generated in the processing space and the second electrode is set to a value at which the exposed portion of the second electrode is sputtered by the plasma. In the organic film processing step, the potential difference between the plasma and the second electrode is set to a value at which an exposed portion of the second electrode is not sputtered by the plasma. It is characterized by that.

  According to the present invention, when the plasma treatment is performed on the inorganic film and the inorganic film of the substrate on which the organic film is formed, the potential difference between the processing space and the second electrode is determined so that the exposed portion of the second electrode The value sputtered by the plasma generated in the processing space is set. However, when an electrode plate made of a silicon-based material is sputtered, it is possible to secure a high selectivity of the organic film in the inorganic film processing. Further, when the plasma treatment is performed on the organic film of the substrate, the potential difference between the plasma and the second electrode is set to a value at which the exposed portion of the second electrode is not sputtered by the plasma. Since the silicon-based material does not jump out of the two electrodes and the silicon-based material does not deposit on the substrate, it is possible to prevent the residue from being generated on the substrate. As a result, the inorganic film processing and organic film processing of the substrate can be performed in a continuous process in the same plasma processing apparatus.

It is sectional drawing which shows schematic structure of the plasma processing apparatus which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between process conditions and the deposit film thickness in the lower surface of an upper electrode plate. It is a flowchart of the plasma processing method which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows schematic structure of the plasma processing apparatus which concerns on the 2nd Embodiment of this invention. FIG. 5 is a cross-sectional view schematically showing a cross-sectional shape of a wafer W to be processed by the plasma processing apparatus 55 of FIG. 4. It is a flowchart of the plasma processing method which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the procedure of the inorganic film processing of step S62, 64 of FIG. It is a flowchart which shows the procedure of the organic film processing process of step S63 of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of the plasma processing apparatus according to the first embodiment. This plasma processing apparatus is configured to perform RIE (Reactive Ion Etching) processing or ashing processing on a semiconductor wafer W as a substrate.

In FIG. 1, a plasma processing apparatus 10 has a cylindrical substrate processing chamber 11, and the substrate processing chamber 11 has a processing space S therein. In the substrate processing chamber 11, for example, a cylindrical susceptor 12 (first electrode) as a mounting table on which a semiconductor wafer W having a diameter of 300 mm (hereinafter simply referred to as “wafer W”) is mounted. Has been placed. The inner wall surface of the substrate processing chamber 11 is covered with a side wall member 45. The side wall member 45 is made of aluminum, and the surface facing the processing space S is coated with yttria (Y ₂ O ₃ ). Further, since the substrate processing chamber 11 is electrically grounded, the potential of the side wall member 45 is the ground potential. The susceptor 12 is installed at the bottom of the substrate processing chamber 11 via an insulating member 29. The side surface of the susceptor 12 is covered with a susceptor side surface covering member 50.

  In the plasma processing apparatus 10, an exhaust path 13 that functions as a flow path for discharging gas molecules above the susceptor 12 out of the substrate processing chamber 11 is formed by the inner wall of the substrate processing chamber 11 and the side surface of the susceptor 12. An annular exhaust plate 14 for preventing plasma leakage is disposed in the exhaust path 13. In addition, the space downstream of the exhaust plate 14 in the exhaust passage 13 wraps around below the susceptor 12 and enters an automatic pressure control valve (hereinafter referred to as “APC valve”) 15 that is a variable butterfly valve. Communicate. The APC valve 15 is connected to a turbo molecular pump (hereinafter referred to as “TMP”) 17 which is an exhaust pump for evacuation through an isolator 16, and the TMP 17 is connected to the valve V 1. Are connected to a dry pump (hereinafter referred to as “DP”) 18 which is an exhaust pump. The exhaust flow path constituted by the APC valve 15, isolator 16, TMP 17, valves V 1 and DP 18 controls the pressure in the substrate processing chamber 11, more specifically the processing space S, by the APC valve 15, and further TMP 17 and DP 18. The pressure in the substrate processing chamber 11 is reduced to a substantially vacuum state.

  A pipe 19 is connected between the isolator 16 and the APC valve 15 to the DP 18 via the valve V2. The pipe 19 and the valve V2 bypass the TMP 17 and roughen the inside of the substrate processing chamber 11 with the DP 18.

A high frequency power supply 20 is connected to the susceptor 12 via a power supply rod 21 and a matcher 22, and the high frequency power supply 20 supplies a high frequency power of a relatively high frequency, for example, 40 MHz, to the susceptor 12. Thereby, the susceptor 12 functions as a lower electrode. The matching unit 22 reduces the reflection of the high frequency power from the susceptor 12 to maximize the supply efficiency of the high frequency power to the susceptor 12. The susceptor 12 applies high frequency power of 40 MHz supplied from the high frequency power supply 20 to the processing space S.

  Further, another high frequency power source 46 is connected to the susceptor 12 via a power supply rod 35 and a matching unit 36. The other high frequency power source 46 has a frequency lower than the high frequency power supplied by the high frequency power source 20, for example, 3. High frequency power of 3.13 MHz is supplied to the susceptor 12. The matching unit 36 has the same function as the matching unit 22.

  A high frequency (3.13 MHz) potential is generated on the surface of the susceptor 12 and the surface of the susceptor side surface covering member 50 due to the supplied high frequency power of 3.13 MHz. Accordingly, since a potential that varies at 3.13 MHz is generated on the surface of the susceptor 12 or the like, the potential of the plasma in the processing space S between the plasma in the processing space S and the surface of the susceptor 12 or the like depends on the potential. A number of cations impinge on the surface of the susceptor 12. The polymer adhering to the surface of the susceptor 12 and the surface of the susceptor side surface covering member 50 is removed by cation collision (sputtering). Although a potential is generated on the surface of the susceptor 12 and the surface of the susceptor side surface covering member 50 due to the high frequency power of 40 MHz, the cation cannot follow the potential difference varying at 40 MHz, and the high frequency power of 40 MHz. Since the potential difference generated due to is small, the energy of the cation colliding with the surface of the susceptor 12 is low.

  A disc-shaped ESC electrode plate 23 made of a conductive film is disposed above the susceptor 12. An ESC DC power source 24 is electrically connected to the ESC electrode plate 23. The wafer W is attracted and held on the upper surface of the susceptor 12 by a Coulomb force or a Johnson-Rahbek force generated by a DC voltage applied to the ESC electrode plate 23 from the ESC DC power source 24. In addition, an annular focus ring 25 is disposed above the susceptor 12 so as to surround the wafer W attracted and held on the upper surface of the susceptor 12. The focus ring 25 is exposed to the processing space S and converges the plasma toward the surface of the wafer W in the processing space S, thereby improving the efficiency of RIE processing and ashing processing.

  Further, for example, an annular refrigerant chamber 26 extending in the circumferential direction is provided inside the susceptor 12. A refrigerant having a predetermined temperature, for example, cooling water or a Galden (registered trademark) liquid, is circulated and supplied to the refrigerant chamber 26 via a refrigerant pipe 27 from a chiller unit (not shown), and the susceptor 12 is supplied depending on the temperature of the refrigerant. The processing temperature of the wafer W attracted and held on the upper surface is controlled.

  Further, a plurality of heat transfer gas supply holes 28 are opened in a portion of the upper surface of the susceptor 12 where the wafer W is adsorbed and held (hereinafter referred to as “adsorption surface”). The plurality of heat transfer gas supply holes 28 are connected to a heat transfer gas supply unit 32 via a heat transfer gas supply line 30 disposed inside the susceptor 12, and the heat transfer gas supply unit 32 serves as a heat transfer gas. Helium gas is supplied to the gap between the adsorption surface and the back surface of the wafer W through the heat transfer gas supply hole 28.

  A plurality of pusher pins 33 as lift pins that can protrude from the upper surface of the susceptor 12 are arranged on the suction surface of the susceptor 12. These pusher pins 33 are connected via a motor (not shown) and a ball screw (not shown), and freely protrude from the suction surface due to the rotational motion of the motor converted into a linear motion by the ball screw. To do. When the wafer W is sucked and held on the suction surface in order to perform RIE processing or ashing processing on the wafer W, the pusher pins 33 are accommodated in the susceptor 12, and the wafer W subjected to RIE processing or ashing processing is transferred from the substrate processing chamber 11. When unloading, the pusher pin 33 protrudes from the upper surface of the susceptor 12 to lift the wafer W away from the susceptor 12 and lift it upward.

  A gas introduction shower head 34 is disposed on the ceiling of the substrate processing chamber 11 so as to face the susceptor 12. The gas introduction shower head 34 includes an electrode plate support 39 made of a conductive material, in which a buffer chamber 40 is formed, and an upper electrode plate 38 (second electrode) supported by the electrode plate support 39. Prepare. The lower surface (exposed portion) of the upper electrode plate 38 is exposed in the processing space S. The upper electrode plate 38 is a disk-shaped member made of a silicon-based conductive material, for example, Si or SiC. The peripheral edge of the upper electrode plate 38 and the peripheral edge of the electrode plate support 39 are covered with an annular insulating member 47 made of an insulating material. That is, the upper electrode plate 38 and the electrode plate support 39 are electrically insulated from each other by the insulating member 47 from the wall portion of the substrate processing chamber 11 that is a ground potential and the susceptor 12 to which high-frequency power is supplied.

  A processing gas introduction pipe 41 from a processing gas supply unit (not shown) is connected to the buffer chamber 40 of the electrode plate support 39. A pipe insulator 42 is disposed in the middle of the processing gas introduction pipe 41. Further, the gas introduction shower head 34 has a plurality of gas holes 37 that allow the buffer chamber 40 to conduct to the processing space S. The gas introduction shower head 34 supplies the processing gas supplied from the processing gas introduction pipe 41 to the buffer chamber 40 to the processing space S via the gas hole 37.

  The upper electrode plate 38 is electrically connected to the DC power source 49 via the high frequency filter 51, and the DC power source 49 applies a negative DC voltage to the upper electrode plate 38. The value of the DC voltage applied to the upper electrode plate 38 by the DC power source 49 is determined by the control unit 52 described later.

  Further, on the side wall of the substrate processing chamber 11, a wafer W loading / unloading port 43 is provided at a position corresponding to the height of the wafer W lifted upward from the susceptor 12 by the pusher pin 33. A gate valve 44 for opening and closing the carry-in / out port 43 is attached.

  In the substrate processing chamber 11 of the plasma processing apparatus 10, as described above, the susceptor 12 applies high-frequency power to the processing space S that is a space between the susceptor 12 and the upper electrode plate 38, thereby processing the processing space S. Then, the processing gas supplied from the gas introduction shower head 34 is made into high-density plasma to generate cations and radicals, and the wafer W is subjected to RIE processing and ashing processing by the cations and radicals.

  The plasma processing apparatus 10 further includes a control unit 52 that controls the operation of each component, a database 53 that stores various data, and an input unit for an operator to input processing conditions and the like, for example, an operation panel (Not shown).

In the plasma processing apparatus 10 described above, an RIE process is performed on the wafer W. At this time, when a deposition process gas, for example, a mixed gas of C ₄ F ₈ gas and argon gas is used, the process gas is generated. The reaction product adheres as a polymer to the lower surface of the upper electrode plate 38, the surface of the susceptor 12, the surface of the side wall member 45, and the surface of the susceptor side surface covering member 50. The deposited polymer forms a deposition film on the surface. Here, as described above, the polymer adhering to the surface of the susceptor 12 and the surface of the susceptor side surface covering member 50 is removed by collision of cations. Further, since the potential of the side wall member 45 is the ground potential, cations collide with the side wall member 45 as well. Therefore, the polymer adhering to the surface of the side wall member 45 is also removed. However, when no DC voltage is applied to the upper electrode plate 38, since the upper electrode plate 38 is electrically insulated, the potential difference between the lower surface of the upper electrode plate 38 and the plasma in the processing space S is reduced, and the upper electrode plate 38 is Ions do not collide with the lower surface of the electrode plate 38, and the polymer attached to the lower surface is not removed.

  In the present embodiment, a potential difference is generated between the lower surface of the upper electrode plate 38 and the plasma in the processing space S in order to remove the polymer adhering to the lower surface of the upper electrode plate 38 by collision of cations. Specifically, the DC power source 49 applies a negative DC voltage to the upper electrode plate 38.

  By the way, in order to examine the value of the negative DC voltage applied to the upper electrode plate 38, the present inventor first applies the DC voltage to the upper electrode plate 38 in the processing space S without applying the DC voltage to the upper electrode plate 38. When plasma is generated from the processing gas, at least one of the processing conditions of the RIE processing, for example, the type of the processing gas introduced into the processing space S, the magnitude of the high-frequency power supplied to the susceptor 12 and the pressure of the processing space S. It was confirmed that the amount of polymer adhering to the lower surface of the upper electrode plate 38 changed according to the conditions. Specifically, it was confirmed that the deposition film thickness on the lower surface of the upper electrode plate 38 changes when the processing conditions (conditions A to H) are changed (FIG. 2). This changes the processing conditions. Specifically, when the pressure of the processing space S or the magnitude of the high frequency power changes, a potential difference is generated between the lower surface of the upper electrode plate 38 and the plasma of the processing space S accordingly. This is because of changes.

  As described above, since the deposition film thickness on the lower surface of the upper electrode plate 38 changes depending on the processing conditions of the RIE process, in this embodiment, the value of the negative DC voltage applied to the upper electrode plate 38 depends on the processing conditions. To decide. Specifically, the deposition film thickness under each processing condition is measured in advance in the plasma processing apparatus 10, and the relationship between the processing condition and the deposition film thickness (hereinafter referred to as “treatment condition-deposition film thickness relationship”). The plasma processing apparatus 10 stores a negative DC voltage value that is stored in the database 53 and that can be removed for each deposition film thickness and that the upper electrode plate 38 itself is not sputtered for each deposition film thickness. The relationship between the film thickness of the deposition film to be removed and the required negative DC voltage value (hereinafter referred to as “deposition film thickness-DC voltage value relationship”) is also stored in the database 53. Then, the control unit 52 determines the negative to be applied to the upper electrode plate 38 from the processing conditions of the RIE process to be executed based on the processing conditions-deposition film thickness relationship and the deposition film thickness-DC voltage value stored in the database 53. Determine the DC voltage value.

  Next, the plasma processing method according to the first embodiment of the present invention will be described.

  FIG. 3 is a flowchart of the plasma processing method according to the first embodiment of the present invention.

  In FIG. 3, first, when an operator inputs processing conditions of RIE processing executed by the plasma processing apparatus 10 via the operation panel, for example, a desired processing gas type, high-frequency power magnitude, and pressure in the processing space S. The control unit 52 determines the type of processing gas, the magnitude of the high-frequency power, and the pressure in the processing space S based on the processing condition-deposition film thickness relationship and the deposition film thickness-DC voltage value stored in the database 53. The value of the negative DC voltage to be applied to the upper electrode plate 38 is determined from at least one (step S31) (voltage value determination step).

  Next, the wafer W is loaded into the substrate processing chamber 11 (step S32), the wafer W is sucked and held on the suction surface of the susceptor 12, and further, the pressure in the substrate processing chamber 11 reaches the pressure under the processing conditions inputted. When the pressure is reduced, the DC power supply 49 starts applying a negative DC voltage having a determined value to the upper electrode plate 38 (step S33) (DC voltage application step), and the gas introduction shower head 34 processes the processing gas. The high frequency power supply 20 and another high frequency power supply 46 supply high frequency power of 40 MHz and 3.13 MHz to the susceptor 12 respectively, and the susceptor 12 processes high frequency power of 40 MHz and 3.13 MHz. Application to the space S is started (step S35). At this time, the processing gas becomes high-density plasma, and cations and radicals are generated in the processing space S. The cations and radicals perform RIE processing on the wafer W (step S36).

  While plasma is generated in the processing space S, a reaction product is generated from the processing gas and adheres as a polymer to the lower surface of the upper electrode plate 38, but a negative DC voltage is applied to the upper electrode plate 38. Therefore, a potential difference is generated between the lower surface of the upper electrode plate 38 and the plasma in the processing space S, and cations collide with the lower surface. Thereby, the polymer adhering to the lower surface of the upper electrode plate 38 is removed.

  When the RIE processing of the wafer W is completed, the high frequency power supply 20 and the other high frequency power supply 46 stop supplying the high frequency power to the susceptor 12 and stop the application of the high frequency power to the processing space S (step S37). At this time, the plasma in the processing space S is also extinguished.

  Next, the DC power supply 49 stops applying a negative DC voltage to the upper electrode plate 38 (step S38), the pressure in the substrate processing chamber 11 is increased to atmospheric pressure, and the wafer W that has been subjected to the RIE process is transferred to the substrate. Unloading from the processing chamber 11 (step S39), the process is terminated.

  According to the process of FIG. 3 described above, since a negative DC voltage is applied to the electrically insulated upper electrode plate 38, there is a potential difference between the plasma in the processing space S and the lower surface of the upper electrode plate 38. As a result, cations collide with the lower surface of the upper electrode plate 38. Therefore, the polymer can be removed from the lower surface of the upper electrode plate 38.

  In the process of FIG. 3, the type of gas introduced into the processing space S and the high-frequency power supplied to the susceptor 12 based on the processing condition-deposition film thickness relationship and the deposition film thickness-DC voltage value stored in the database 53. The value of the negative DC voltage applied to the upper electrode plate 38 is determined from at least one of the magnitude of the pressure and the pressure in the processing space S. The film thickness of the deposit film on the lower surface of the upper electrode plate 38 is related to at least one of the kind of the gas, the magnitude of the high-frequency power, and the pressure. Further, the negative DC voltage value in the relationship between the deposition film thickness and the DC voltage value stored in the database 53 is a negative DC voltage value at which the deposition film can be removed and the upper electrode plate 38 itself is not sputtered. . Therefore, it is possible to appropriately control the amount of sputtering caused by cations colliding with the lower surface, so that it is possible to appropriately remove the polymer from the upper electrode plate 38 and to prevent the upper electrode plate 38 from being consumed. .

  In the process of FIG. 3, a negative DC voltage is applied to the upper electrode plate 38 while the high frequency power supply 20 and the other high frequency power supply 46 are supplying high frequency power to the susceptor 12. While high frequency power is supplied to the susceptor 12, plasma is generated in the processing space S, and reaction products are generated from the processing gas and adhere to the lower surface of the upper electrode plate 38 as a polymer. Is applied, so the polymer is removed by cation collisions. Therefore, the polymer can be reliably removed from the upper electrode plate 38.

  In the process of FIG. 3 described above, the value of the negative DC voltage applied to the upper electrode plate 38 may be 0 V to 2000 V, which is a value that does not affect the plasma, and more preferably 50 V to 200 V. There should be.

  In order to control the plasma distribution and the like, a negative DC voltage applied to the upper electrode plate 38 may be used. In this case, the value of the negative DC voltage is not limited to the above-described value.

  In the present embodiment described above, the polymer attached to the lower surface of the upper electrode plate 38 is removed by applying a negative DC voltage, but the object of removal is not limited to this. For example, the oxide film formed on the lower surface of the upper electrode plate 38 can also be removed by applying a negative DC voltage.

  In the above-described embodiment, the negative DC voltage value to be applied is determined according to the processing conditions of the RIE process to be performed before the wafer W is subjected to the RIE process. The value of the negative DC voltage may be appropriately changed according to the amount of plasma emitted in the space S and the amount of polymer adhering to the lower surface of the upper electrode plate 38. As a method of measuring the amount of polymer adhering to the lower surface of the upper electrode plate 38, a part of the optical fiber having both ends arranged outside the substrate processing chamber 11 is exposed in the substrate processing chamber 11, and the optical fiber For example, a method for monitoring transmittance is applicable. Since the transmittance of the optical fiber changes when the polymer is attached to the optical fiber, the amount of the polymer attached to the lower surface of the upper electrode plate 38 can be measured by this method.

  In the above-described embodiment, the plasma processing apparatus 10 includes the control unit 52 and the database 53. However, an external server or database connected to the plasma processing apparatus 10 may perform the same function.

  Next, a plasma processing apparatus according to the second embodiment of the present invention will be described.

  This embodiment is basically the same in configuration and operation as the first embodiment described above, and differs from the first embodiment described above in that a switch is provided between the DC power supply and the high frequency filter. . Therefore, the description of the duplicated configuration and operation is omitted, and the description of the different configuration and operation is given below.

  FIG. 4 is a cross-sectional view showing a schematic configuration of a plasma processing apparatus according to the second embodiment of the present invention.

  In FIG. 4, the plasma processing apparatus 55 includes a switch 54 (switch means) disposed between the DC power supply 49 and the high frequency filter 51.

  When the switch 54 is turned on, the upper electrode plate 38 is electrically connected to the DC power source 49 via the high frequency filter 51, and the DC power source 49 applies a DC voltage to the upper electrode plate 38. The control unit 52 determines the value of the DC voltage applied to the upper electrode plate 38 by the DC power source 49. The upper electrode plate 38 is in an electrically floating state (hereinafter referred to as “floating state”) when the switch 54 is turned off. On / off of the switch 54 is controlled by the control unit 52 described later.

  FIG. 5 is a cross-sectional view schematically showing the cross-sectional shape of the wafer W to be processed by the plasma processing apparatus 55 of FIG. In the present embodiment, a case where a multilayer resist film is formed on the wafer W will be described.

Multilayer resist film on the wafer W, as shown in FIG. 5, first, on the SiO ₂ film 62 to be processed which is formed on the Si substrate 61 (inorganic film), the etching selectivity with respect to the SiO ₂ film 62 An amorphous carbon film 63 (organic film) having, an SOG film 64 (inorganic film) having etching selectivity with respect to the amorphous carbon film 63, and a resist film 65 are sequentially formed. The SOG film 64 is made of, for example, SiO ₂ or SiOC.

In the present embodiment, the processing process on the wafer W on which the multilayer resist film is formed is continuously executed in the same chamber. Specifically, after patterning the resist film 65 by photolithography, the SOG film 64 is etched using the resist film 65 as a mask, and the pattern of the resist film 65 is transferred to the SOG film 64. Next, the amorphous carbon film 63 is etched using the patterned SOG film 64 as a mask, and the pattern of the SOG film 64 is transferred to the amorphous carbon film 63. Then, the processed SiO ₂ film 62 is processed using the patterned amorphous carbon film 63 as a mask.

More specifically, in the etching of the SOG film 64 and the SiO ₂ film 62, when the pressure in the substrate processing chamber 11 into which the wafer W has been loaded is set to the pressure in the processing conditions input to the operation panel or the like, it is input. A DC voltage having a value determined based on the processing conditions is applied to the upper electrode plate 38, and a CF processing gas typified by C ₄ F ₈ is supplied to the processing space S from the gas introduction shower head 34. The high frequency power of 40 MHz and 3.13 MHz supplied from the high frequency power supply 20 and the other high frequency power supply 46 to the susceptor 12 is applied to the processing space S, and the supplied processing gas is generated into a high-density plasma. The wafer W is subjected to RIE treatment with cations or radicals.

On the other hand, in the etching of the amorphous carbon film 63, the upper electrode plate 38 is brought into a floating state by turning off the switch 54 based on the inputted processing conditions, and the pressure in the substrate processing chamber 11 into which the wafer W is loaded is inputted. When the pressure is set to the specified processing conditions, a processing gas not containing F such as O ₂ , CO, N ₂ , and H ₂ is supplied from the gas introduction shower head 34 to the processing space S, and the susceptor 12 is supplied with the high-frequency power source 20. A high-frequency power of 40 MHz or more supplied from is applied to the processing space S, and the wafer W is subjected to RIE processing by cations and radicals generated by the supplied processing gas becoming high-density plasma.

  Next, a plasma processing method according to the second embodiment of the present invention will be described.

  FIG. 6 is a flowchart of the plasma processing method according to the second embodiment of the present invention.

  In FIG. 6, first, the operator inputs the processing conditions of the RIE processing executed by the plasma processing apparatus 55 via the operation panel, for example, the type of desired processing gas, the magnitude of the high frequency power, and the pressure in the processing space S. .

  Next, the wafer W is carried into the substrate processing chamber 11 (step S61), the wafer W is sucked and held on the suction surface of the susceptor 12, and an inorganic film processing process (step S62) in FIG. ), The organic film processing (step S63) (organic film processing step) in FIG. 8 and the inorganic film processing (step S64) (inorganic film processing step) in FIG. 7 are performed in this order, and the pressure in the substrate processing chamber 11 is increased. The pressure is increased to atmospheric pressure, the wafer W subjected to the RIE process in each processing process is unloaded from the substrate processing chamber 11 (step S65), and this process ends.

In the inorganic film processing in step S62, the SOG film 64 is etched, and at this time, the pattern of the resist film 65 is transferred to the SOG film 64. In the organic film processing in step S63, the amorphous carbon film 63 is etched, and the pattern of the SOG film 64 is transferred to the amorphous carbon film 63. In the inorganic film processing in step S64, the SiO ₂ film 62 is etched. At this time, the patterned amorphous carbon film 63 functions as a mask. Thereby, the SiO ₂ film 62 patterned into a desired pattern is obtained.

  FIG. 7 is a flowchart showing the procedure of the inorganic film processing in steps S62 and S64 of FIG.

  In FIG. 7, first, the control unit 52 determines the value of the DC voltage to be applied to the upper electrode plate 38 based on the processing conditions of the RIE processing input by the operator (step S71).

Next, when the pressure in the substrate processing chamber 11 into which the wafer W has been loaded is reduced or increased to the pressure under the input processing conditions, the control unit 52 turns on the switch 54 and the DC power source 49 determines the value determined above. Is started to be applied to the upper electrode plate 38 (step S72) (DC power supply connection step). Next, the gas introduction shower head 34 mainly supplies a CF-based processing gas typified by C ₄ F ₈ to the processing space S (step S73), and the high-frequency power source 20 and the other high-frequency power sources 46 are 40 MHz and 3. The high frequency power of 13 MHz is supplied to the susceptor 12, and the susceptor 12 starts to apply the high frequency power of 40 MHz and 3.13 MHz to the processing space S (step S74). At this time, the processing gas becomes high-density plasma, and cations and radicals are generated in the processing space S. The cations and radicals perform RIE processing on the wafer W (step S75).

In step S75, since a DC voltage is applied to the upper electrode plate 38, a potential difference is generated between the lower surface of the upper electrode plate 38 and the plasma in the processing space S. Cations are drawn into the upper electrode plate 38 due to the potential difference, and the upper electrode plate 38 is sputtered. As described above, when an electrode plate made of a silicon-based material is sputtered, a high selectivity of the inorganic film to the mask film can be realized in the inorganic film processing. Therefore, in step S75, it is possible to secure a high selection ratio of the resist film 65 in the etching of the SOG film 64 and a high selection ratio of the amorphous carbon film 63 in the etching of the SiO ₂ film 62.

  Although the mechanism of the effect of sputtering of an electrode plate made of a silicon-based material is difficult to explain clearly, as a result of intensive studies, the present inventor analogizes the two hypotheses described below. It came to do.

  (1) A silicon-based material pops out by sputtering of an electrode plate made of a silicon-based material and is deposited on the mask film. Thereafter, even if plasma cations or radicals reach the mask film, they are consumed for etching the deposited silicon-based material, and the mask film is hardly etched.

  (2) In etching by plasma of CF-based gas, CF-based deposits as reaction products are generated and deposited on the mask film to form a deposited film. Further, the fluorine ions and fluorine radicals of the CF-based gas are consumed during sputtering of the electrode plate. Therefore, the generated CF-based deposit contains a large amount of carbon (becomes carbon-rich). When a large amount of carbon is contained, the deposited film is strengthened and is difficult to be etched. As a result, the deposition film protects the mask film, and the mask film is hardly etched.

  Next, when the RIE processing of the wafer W is completed, the high frequency power supply 20 and the other high frequency power supply 46 stop supplying the high frequency power to the susceptor 12 and stop applying the high frequency power to the processing space S (step S76). . At this time, the plasma in the processing space S is also extinguished.

  Next, the DC power supply 49 stops applying the DC voltage to the upper electrode plate 38 (step S77), and this process is terminated.

According to the inorganic film processing shown in FIG. 7, since a DC voltage is applied to the upper electrode plate 38, a potential difference is generated between the plasma in the processing space S and the lower surface of the upper electrode plate 38, and the upper electrode plate 38. The cations collide with the lower surface of the surface. That is, since the upper electrode plate 38 is sputtered, it is possible to secure a high selectivity of the resist film 65 in the etching of the SOG film 64 and a high selectivity of the amorphous carbon film 63 in the etching of the SiO ₂ film 62. it can.

  In the present embodiment, a DC voltage is applied to the upper electrode plate 38. However, the upper electrode plate 38 may be switched from a floating state to a ground state, and a high DC voltage (Vdc) is applied to the upper electrode plate 38. It is good also as a structure which applies the high frequency electric power of 27 MHz or less which can generate | occur | produce.

  FIG. 8 is a flowchart showing the procedure of the organic film processing in step S63 of FIG.

  In FIG. 8, first, based on the processing conditions of the RIE process input by the operator, the control unit 52 turns off the switch 54 and puts the upper electrode plate 38 into a floating state (step S81).

Next, when the pressure in the substrate processing chamber 11 is reduced or increased to the pressure under the input processing conditions, the gas introduction shower head 34 uses a processing gas containing no F, such as O ₂ , CO, N ₂ , and H _2. The high frequency power supply 20 supplies high frequency power of 40 MHz or higher to the susceptor 12 and the susceptor 12 starts applying high frequency power of 40 MHz or higher to the processing space S (step S83). . At this time, the processing gas becomes high-density plasma, and cations and radicals are generated in the processing space S. The cations and radicals perform RIE processing on the wafer W (step S84).

  In this process, since the processing gas supplied to the processing space S is a gas that does not contain F, no reaction product is generated from the processing gas while plasma is generated in the processing space S, and the upper electrode plate No polymer adheres to the lower surface of 38.

  Further, since the upper electrode plate 38 is in a floating state, the upper electrode plate 38 receives charges from the plasma in the processing space S, and the charges do not flow out of the upper electrode plate 38, thereby the upper electrode plate 38. 38 is charged up, and the potential difference between the lower surface of the upper electrode plate 38 and the plasma in the processing space S becomes smaller. As a result, the energy of cations that collide with the lower surface of the upper electrode plate 38 is reduced, and the lower surface of the upper electrode plate 38 is not sputtered. Accordingly, the silicon-based material does not jump out of the upper electrode plate 38 and the silicon-based material is not deposited on the wafer W, so that generation of a residue on the wafer W can be prevented.

  When the RIE processing of the wafer W is completed, the high frequency power supply 20 stops the supply of the high frequency power to the susceptor 12 and stops the application of the high frequency power to the processing space S (step S85). At this time, the plasma in the processing space S is also extinguished. Then, this process ends.

  According to the organic film processing of FIG. 8, since the upper electrode plate 38 is brought into a floating state, the potential difference between the plasma in the processing space S and the lower surface of the upper electrode plate 38 is reduced, and the lower surface of the upper electrode plate 38 is The energy of colliding cations is lowered. Therefore, since the lower surface of the upper electrode plate 38 is not sputtered, the material of the silicon-based upper electrode plate 38 can be prevented from being deposited on the wafer.

  In the present embodiment, the upper electrode plate 38 is in a floating state, but the potential applied to the upper electrode plate 38 is 50 eV or less, which is lower than the threshold at which the sputtering yield of the material of the silicon-based upper electrode plate 38 rises. It is good also as composition which becomes.

According to the plasma treatment of FIG. 6, it is possible to secure a high selectivity of the resist film 65 in the etching of the SOG film 64 and secure a high selectivity of the amorphous carbon film 63 in the etching of the SiO ₂ film 62. It is possible to prevent the residue from being generated on the wafer W during the etching of the amorphous carbon film 63. That is, the inorganic film processing and the organic film processing of the wafer W can be performed in a continuous process in the same plasma processing apparatus.

  In the above-described embodiment, the plasma processing apparatus 55 includes the control unit 52 and the database 53. However, an external server or database connected to the plasma processing apparatus 55 may perform the same function.

  In addition, the substrate on which the RIE process or the like is performed in the plasma processing apparatuses 10 and 55 described above is not limited to a semiconductor wafer for a semiconductor device, but various substrates used for LCD (Liquid Crystal Display), FPD (Flat Panel Display), etc. It may be a photomask, a CD substrate, a printed circuit board, or the like.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus. It is also achieved by reading and executing the program code stored in the storage medium.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the program code and the storage medium storing the program code constitute the present invention.

  Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, and a DVD. An optical disc such as RW or DVD + RW, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used. Alternatively, the program code may be downloaded via a network.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) running on the computer based on the instruction of the program code, etc. Includes a case where part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.

  Furthermore, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the expanded function is based on the instruction of the program code. This includes a case where a CPU or the like provided on the expansion board or the expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

S processing space W semiconductor wafer 10 plasma processing apparatus 11 substrate processing chamber 12 susceptor 20 high frequency power supply 34 gas introduction shower head 38 upper electrode plate 46 other high frequency power supply 49 DC power supply 52 control unit 53 database 54 switch

Claims (14)

A substrate processing chamber having a processing space into which the substrate is carried in and performing plasma processing on the substrate in the processing space; a first electrode disposed in the substrate processing chamber and connected to a high-frequency power source;
In the plasma processing apparatus comprising the exposed portion exposed in the processing space and the second electrode electrically insulated from the substrate processing chamber and the first electrode,
An inorganic film and an organic film are formed on the substrate,
The exposed portion is made of a silicon-based material,
When plasma processing is performed on the inorganic film of the substrate, the potential difference between the plasma generated in the processing space and the second electrode is set to a value at which the exposed portion of the second electrode is sputtered by the plasma. Set,
When performing plasma treatment on the organic film of the substrate, the potential difference between the plasma and the second electrode is set to a value at which the exposed portion of the second electrode is not sputtered by the plasma. A plasma processing apparatus.   The plasma processing apparatus according to claim 1, wherein the second electrode is connected to a DC power source.   When the plasma treatment is performed on the organic film of the substrate, the electrical connection between the second electrode and the DC power source is interrupted, and the second electrode and the DC power source are cut off. 3. The plasma processing apparatus according to claim 2, further comprising switch means for electrically insulating the electrodes.   The plasma processing apparatus according to claim 1, wherein the second electrode is grounded when the inorganic film on the substrate is subjected to plasma processing.   2. The plasma processing apparatus according to claim 1, wherein when the plasma treatment is performed on the inorganic film of the substrate, a high frequency power of 27 MHz or less that generates a desired DC voltage is applied to the second electrode.   The plasma processing apparatus according to claim 1, wherein the second electrode is electrically insulated when plasma processing is performed on the organic film of the substrate.   2. The plasma according to claim 1, wherein when the plasma treatment is performed on the organic film of the substrate, the potential of the second electrode is set to 50 eV or less, which is a threshold value at which a sputtering yield of a silicon-based material rises. Processing equipment. A substrate processing chamber having a processing space into which the substrate is loaded and performing plasma processing on the substrate in the processing space; a first electrode disposed in the substrate processing chamber and connected to a high-frequency power source; and the processing space A plasma processing method in a plasma processing apparatus comprising: an exposed portion exposed to the substrate; and a second electrode electrically insulated from the substrate processing chamber and the first electrode,
An inorganic film and an organic film are formed on the substrate,
The exposed portion is made of a silicon-based material,
An inorganic film treatment step of performing plasma treatment on the inorganic film of the substrate;
An organic film processing step of performing plasma processing on the organic film of the substrate,
In the inorganic film processing step, the potential difference between the plasma generated in the processing space and the second electrode is set to a value at which an exposed portion of the second electrode is sputtered by the plasma,
In the organic film processing step, the potential difference between the plasma and the second electrode is set to a value at which an exposed portion of the second electrode is not sputtered by the plasma. .   The plasma processing method according to claim 8, further comprising a DC power supply connecting step of connecting a DC power supply to the second electrode.   The plasma processing method according to claim 8, wherein in the inorganic film processing step, the second electrode is grounded.   9. The plasma processing method according to claim 8, wherein in the inorganic film processing step, high frequency power of 27 MHz or less that generates a desired DC voltage is applied to the second electrode.   9. The plasma processing method according to claim 8, wherein the organic film processing step electrically insulates the second electrode.   9. The plasma processing method according to claim 8, wherein in the organic film processing step, the potential of the second electrode is set to 50 eV or less which is a threshold value at which a sputtering yield of a silicon-based material rises. A substrate processing chamber having a processing space into which the substrate is loaded and performing plasma processing on the substrate in the processing space; a first electrode disposed in the substrate processing chamber and connected to a high-frequency power source; and the processing space A program for causing a computer to execute a plasma processing method in a plasma processing apparatus having an exposed portion exposed to the substrate and having a second electrode electrically insulated from the substrate processing chamber and the first electrode is stored. A computer-readable storage medium,
An inorganic film and an organic film are formed on the substrate,
The exposed portion is made of a silicon-based material,
The plasma processing method includes:
An inorganic film treatment step of performing plasma treatment on the inorganic film of the substrate;
An organic film processing step of performing plasma processing on the organic film of the substrate,
In the inorganic film processing step, the potential difference between the plasma generated in the processing space and the second electrode is set to a value at which an exposed portion of the second electrode is sputtered by the plasma,
In the organic film processing step, the potential difference between the plasma and the second electrode is set to a value at which an exposed portion of the second electrode is not sputtered by the plasma. A storage medium.

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