JP2006210461A - Process apparatus cleaning method, program for executing the method, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process apparatus cleaning method capable of preventing generation of particles in a chamber, a program for executing the method, and a storage medium.
A plasma processing apparatus including a chamber for performing plasma processing on a wafer and a CPU for controlling the operation of each component includes a first condition defined by a gas flow rate and a gas molecular weight of a processing gas, Specifically, the processing gas is introduced into the chamber 10 based on the product A ₁ (= Q ₁ × m ₁ ) of the processing gas flow rate Q ₁ and the molecular weight m ₁ , and the surface of the wafer W is physically or chemically introduced. After the etching, a pre-purge gas different from the processing gas is introduced into the chamber 10 from the shower head 33 based on the second condition guided based on the first condition.
[Selection] Figure 2

Description

  The present invention relates to a process apparatus cleaning method, a program for executing the method, and a storage medium, and more particularly to a process apparatus cleaning method having a chamber in which a plasma atmosphere of a process gas is formed.

  2. Description of the Related Art Conventionally, when a process gas or purge gas is introduced into a chamber in a storage chamber that accommodates a substrate, for example, a chamber, gas viscous force generated by the flow of these gases causes the inner wall of the chamber or the electrode surface in the chamber. It has been confirmed that the adhered particles are scattered. If the scattered particles adhere to the substrate, an etching residue is generated as a mask when the substrate is subjected to an etching process. Also, when the film formation process is performed, the particle acts as a nucleus to deteriorate the film quality. There is a problem that it ends up. Since introduction of process gas and purge gas into the chamber is indispensable when processing a substrate, recently, in order to solve such a problem, measures to prevent scattering of particles when gas is introduced into the chamber. Is required.

For example, in Patent Document 1, a plasma generation chamber formed as a cylindrical resonator, a first excitation coil concentrically surrounding the plasma generation chamber, and a position far from the wafer mounting surface of the sample stage from the first excitation coil. In an apparatus comprising: a second excitation coil arranged coaxially with the first excitation coil; and a vacuum pumping device including a turbo molecular pump and a dry pump connected to a back pressure side of the turbo molecular pump. A mirror magnetic field is formed by one excitation coil and a second excitation coil, and the mirror magnetic field and the gas pressure in the apparatus are set to 1.3 × 10 ^{−2 to} 1.3 × 10 ⁻¹ kPa (0.1 to 1.0 Torr). The inside of the apparatus is cleaned using the gas in the high pressure region, and the mirror magnetic field and the gas pressure in the apparatus are set to 6.7 × 10 ^{−3 to} 1.3 × 10 ⁻¹ kPa (5.0 × 10 10). ^-2 to A method for cleaning the inside of the apparatus using a gas in a low pressure region at 1.0 Torr) is disclosed.

Further, in Patent Document 2, in a dry etching apparatus including a chamber, circular upper and lower electrodes arranged in the chamber so as to be parallel to each other, and a gas introduction pipe for introducing a process gas or the like into the chamber. After sufficient vacuum evacuation in the chamber, oxygen gas as a cleaning gas is introduced into the chamber from the gas introduction pipe, and the pressure in the chamber is adjusted by controlling the balance between gas supply and exhaust, A method of removing carbon-based deposits adhering to the inside of the chamber by oxygen active species by applying predetermined power to the upper electrode and the lower electrode to turn oxygen gas into plasma is disclosed.
JP-A-4-186833 JP 2000-195830 A

  However, when removing carbon-based deposits, etc., that cause generation of particles, the carbon-based deposits can be removed uniformly if the power applied to the upper and lower electrodes and the pressure in the chamber are not optimal. In addition, there is a possibility that parts in the chamber may be damaged, and as a result, particles are generated in the chamber.

  An object of the present invention is to provide a process apparatus cleaning method capable of preventing the generation of particles in a chamber, a program for executing the method, and a storage medium.

  In order to achieve the above object, a cleaning method for a process apparatus according to claim 1 is a cleaning method for a process apparatus including a processing chamber for performing plasma processing on an object to be processed. A plasma processing step of performing plasma processing using plasma generated from a gas introduced based on a first condition defined by a gas molecular weight, and a gas based on a second condition derived based on the first condition And a gas introduction step of introducing gas.

  The process apparatus cleaning method according to claim 2, further comprising a plasma conversion step of converting the inside of the processing chamber into plasma after the gas introduction step. .

  3. The process apparatus cleaning method according to claim 3, wherein the gas introduced in the plasma treatment step is the same as the gas in the gas introduction step. And

  A process apparatus cleaning method according to a fourth aspect of the present invention is the process apparatus cleaning method according to the first or second aspect, wherein the gas in the plasma treatment step is different from the gas in the gas introduction step.

  The process apparatus cleaning method according to claim 5 is the process apparatus cleaning method according to claim 1 or 2, wherein the gas in the gas introduction step is the same as the gas in the plasma step.

The process apparatus cleaning method according to claim 6 is the process apparatus cleaning method according to any one of claims 1 to 5, wherein the product A of the gas flow rate and the gas molecular weight in the second condition is It is characterized by being larger than the product A _x of the gas flow rate and the gas molecular weight under the condition of 1.

The process apparatus cleaning method according to claim 7 is the process apparatus cleaning method according to any one of claims 2 to 6, wherein the gas flow rate introduced into the processing chamber in the plasma step is 1. The pressure in the processing chamber is 1.3 × 10 ^{−2 to} 4.0 × 10 ⁻² kPa (100 to 300 mTorr), and is applied in the processing chamber at least ⁴ Pa · m ³ / s (800 sccm). The high-frequency power is 200 to 400 W.

In order to achieve the above object, a program according to claim 8 is a program for causing a computer to execute a cleaning method of a process apparatus including a processing chamber for plasma-processing an object to be processed. A plasma processing module for performing plasma processing using plasma generated from a gas introduced based on at least a first condition defined by a gas flow rate and a gas molecular weight; and a second condition derived based on the first condition And the product A of the gas flow rate and the gas molecular weight under the second condition is larger than the product A _x of the gas flow rate and the gas molecular weight under the first condition. It is characterized by.

To achieve the above object, a storage medium according to claim 9 stores a computer-readable program for causing a computer to execute a cleaning method for a process apparatus including a processing chamber for plasma-processing an object to be processed. A plasma processing module for performing plasma processing on the object to be processed using plasma generated from a gas introduced based on at least a first condition defined by a gas flow rate and a gas molecular weight; A gas introduction module that introduces a gas based on a second condition derived based on the first condition, and the product A of the gas flow rate and the gas molecular weight in the second condition is It is larger than the product a _x of the gas flow rate and gas molecular weight in the conditions.

  According to the cleaning method for a process apparatus according to claim 1, the object to be processed is plasma-treated using plasma generated from a gas introduced based on at least a first condition defined by a gas flow rate and a gas molecular weight, Since the gas is introduced based on the second condition derived based on the first condition, the particles can be removed from the processing chamber by the gas viscous force of the gas introduced based on the second condition. Thus, generation of particles in the processing chamber can be prevented.

  According to the process apparatus cleaning method of the second aspect, since the inside of the processing chamber is converted into plasma after the gas introduction step, deposits that cause generation of particles can be removed by plasma generated from the gas. Therefore, generation of particles in the processing chamber can be further prevented.

  According to the cleaning method for a process apparatus according to claim 3, since the gas introduced in the plasma processing step is the same as the gas in the gas introduction step, the gas introduced into the processing chamber can be easily changed without changing. Particles can be removed from within the processing chamber.

  According to the cleaning method for a process apparatus according to claim 4, since the gas in the plasma processing step is different from the gas in the gas introduction step, a gas capable of providing a gas viscous force capable of more effectively removing particles is selected. be able to.

  According to the cleaning method for a process apparatus according to claim 5, since the gas in the gas introduction step is the same as the gas in the plasma step, the particles can be more easily formed without changing the gas introduced into the processing chamber. It can be removed from within the processing chamber.

According to the cleaning method for a process apparatus according to claim 6, since the product A of the gas flow rate and the gas molecular weight in the second condition is larger than the product A _x of the gas flow rate and the gas molecular weight in the first condition, Particles can be reliably removed from the processing chamber by the gas viscous force of the gas introduced based on the conditions.

According to the method for cleaning a process apparatus according to claim 7, in the plasma step, the flow rate of the gas introduced into the processing chamber is 1.4 Pa · m ³ / s (800 sccm) or more, and the pressure in the processing chamber is 1. Since 3 × 10 ^{−2 to} 4.0 × 10 ⁻² kPa (100 to 300 mTorr) and high-frequency power applied to the processing chamber is 200 to 400 W, the plasma chamber generates parts from the processing chamber. Deposits can be removed without damage.

According to the program according to claim 8 and the storage medium according to claim 9, the object to be processed is generated using plasma generated from a gas introduced based on at least a first condition defined by a gas flow rate and a gas molecular weight. The gas is introduced based on the second condition that is plasma-treated and guided based on the first condition, and the product A of the gas flow rate and the gas molecular weight in the second condition is the gas flow rate and gas molecular weight in the first condition. because of greater than the product a _x, that the second condition by the gas viscous force of gas introduced based on the can to remove particles from the processing chamber, to prevent the generation of particles in the processing chamber with it can.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a plasma processing apparatus to which a process apparatus cleaning method according to an embodiment of the present invention is applied.

  In FIG. 1, a plasma processing apparatus 1 configured as an etching processing apparatus for performing an etching process on a wafer W has a cylindrical chamber (processing chamber) 10 made of metal, for example, aluminum or stainless steel. For example, a cylindrical susceptor 11 as a stage on which a wafer W having a diameter of 300 mm is placed is disposed.

Between the side wall of the chamber 10 and the susceptor 11, the gas above the susceptor 11 is allowed to pass through the chamber 1.
An exhaust path 12 is formed which functions as a flow path for discharging to the outside of zero. An annular baffle plate 13 is disposed in the middle of the exhaust passage 12, and a space downstream from the baffle plate 13 of the exhaust passage 12 is an automatic pressure control valve (hereinafter referred to as an "automatic pressure control valve"). APC ”) 14). The APC 14 is connected to a turbo molecular pump (hereinafter referred to as “TMP”) 15 that is an exhaust pump for evacuation, and further connected to a dry pump (hereinafter referred to as “DP”) 16 that is an exhaust pump via the TMP 15. Yes. APC1
4. The exhaust flow path constituted by TMP15 and DP16 is hereinafter referred to as “main exhaust line”. This main exhaust line not only controls the pressure in the chamber 10 by the APC 14, but also passes through the chamber 10 by the TMP15 and DP16. Depressurize until almost vacuum.

Further, the space downstream of the baffle plate 13 of the exhaust passage 12 described above is connected to an exhaust passage (hereinafter referred to as “roughing line”) different from the main exhaust line. The roughing line communicates the space with the DP 16 and has an exhaust pipe 17 having a diameter of, for example, 25 mm, and the exhaust pipe 1.
7 and a valve V2 disposed in the middle. The valve V2 can block the space and the DP 16 from each other. The roughing line discharges the gas in the chamber 10 by DP16.

  The susceptor 11 is connected to a high frequency power source 18 that applies predetermined high frequency power to the susceptor 11. In addition, a disk-shaped electrode plate 20 made of a conductive film for adsorbing the wafer W with an electrostatic adsorption force is disposed above the susceptor 11. A DC power source 22 is electrically connected to the electrode plate 20. The wafer W is attracted and held on the upper surface of the susceptor 11 by a Coulomb force or a Johnson-Rahbek force generated by a DC voltage applied to the electrode plate 20 from the DC power source 22. When the wafer W is not attracted, the electrode plate 20 is disconnected from the DC power source 22 and is in a floating state. An annular focus ring 24 made of silicon (Si) or the like converges the plasma generated above the susceptor 11 toward the wafer W.

  Inside the susceptor 11, for example, an annular refrigerant chamber 25 extending in the circumferential direction is provided. A coolant having a predetermined temperature, for example, cooling water, is circulated and supplied from the chiller unit (not shown) to the coolant chamber 25 through a pipe 26, and the processing temperature of the wafer W on the susceptor 11 is controlled by the temperature of the coolant. Is done.

A plurality of heat transfer gas supply holes 27 and heat transfer gas supply grooves (not shown) are arranged on a portion of the upper surface of the susceptor 11 where the wafer W is adsorbed (hereinafter referred to as “adsorption surface”). These heat transfer gas supply holes 27 and the like communicate with a heat transfer gas supply pipe 29 having a valve V3 via a heat transfer gas supply line 28 disposed inside the susceptor 11, and are connected to the heat transfer gas supply pipe 29. A heat transfer gas from a connected heat transfer gas supply unit (not shown), for example, He gas, is adsorbed on the adsorption surface and the wafer W.
Supply the gap with the back of the. As a result, heat transfer between the wafer W and the susceptor 11 is improved. The valve V3 can block the heat transfer gas supply hole 27 and the like from the heat transfer gas supply unit.

In addition, a plurality of pusher pins 30 as lift pins that can protrude from the upper surface of the susceptor 11 are disposed on the suction surface. These pusher pins 30 are motors (not shown).
Is moved in the vertical direction in the figure by being converted into a linear motion by a ball screw or the like. When the wafer W is attracted and held on the attracting surface, the pusher pins 30 are connected to the susceptor 1.
When the wafer W accommodated in the wafer 1 and subjected to the plasma processing due to the etching process or the like is unloaded from the chamber 10, the pusher pin 30 protrudes from the upper surface of the susceptor 11 to separate the wafer W from the susceptor 11 and move upward. Lift up.

  A shower head 33 is disposed on the ceiling of the chamber 10. A high frequency power source 52 is connected to the shower head 33, and the high frequency power source 52 applies a predetermined high frequency power to the shower head 33. Thereby, the shower head 33 functions as an upper electrode.

The shower head 33 includes a lower electrode plate 35 having a large number of gas vent holes 34 and an electrode support 36 that detachably supports the electrode plate 35. Further, a buffer chamber 37 is provided inside the electrode support 36, and a processing gas introduction pipe 38 from a processing gas supply unit (not shown) is connected to the buffer chamber 37. A valve V <b> 1 is disposed in the middle of the processing gas introduction pipe 38. The valve V1 can shut off the buffer chamber 37 and the processing gas supply unit. Here, the inter-electrode distance D between the susceptor 11 and the shower head 33 is, for example,
It is set to 27 ± 1 mm or more.

  A flow rate control device 39 for controlling the flow rate of the processing gas or the like introduced into the chamber 10 is attached to the upstream side of the valve V 1 of the processing gas introduction pipe 38. The flow rate control device 39 is electrically connected to a CPU 53 described later, and controls the flow rates of the processing gas and purge gas introduced into the chamber 10 based on a signal from the CPU 53.

A gate valve 32 for opening and closing the loading / unloading port 31 for the wafer W is attached to the side wall of the chamber 10. In the chamber 10 of the plasma processing apparatus 1, as described above, high-frequency power is applied to the susceptor 11 and the shower head 33, and high-density plasma is generated from the processing gas in the space S by the applied high-frequency power. Ions and radicals are generated.

  In addition, the plasma processing apparatus 1 includes a CPU 53 disposed inside or outside thereof. This CPU 53 is connected to valves V1, V2, V3, APC14, TMP15, DP16, high frequency power supplies 18, 52, flow control device 39, and DC power supply 22, and each component according to a user command or a predetermined process recipe. To control the operation.

In this plasma processing apparatus 1, during the etching process, first, the gate valve 32 is opened, the wafer W to be processed is loaded into the chamber 10 and placed on the susceptor 11, and the gate valve 32 is closed. To do. Then, a processing gas (for example, a mixed gas composed of C ₄ F ₈ gas, O ₂ gas, and Ar gas at a predetermined flow rate ratio) is supplied from the shower head 33 based on the first condition defined by the gas flow rate and the gas molecular weight. The pressure in the chamber 10 is set to a predetermined value by the APC 14 or the like. Next, high frequency power is applied from the high frequency power source 52 to the shower head 33, high frequency power is applied from the high frequency power source 18 to the susceptor 11, and a DC voltage is applied from the DC power source 22 to the electrode plate 20. Is adsorbed onto the susceptor 11. Then, the processing gas discharged from the shower head 33 is turned into plasma as described above. The radicals and ions generated by the plasma are focused on the surface of the wafer W by the focus ring 24, and the surface of the wafer W is physically or chemically etched.

  After the wafer W is etched, the gate valve 32 is opened, the wafer W placed on the susceptor 11 is unloaded from the chamber 10, and the gate valve 32 is closed again.

  Next, before carrying another wafer W to be processed into the chamber 10, a cleaning process to be described later is performed to clean the inside of the chamber 10, and then the gate valve 32 is opened so that another wafer W can be opened. The wafer W is loaded into the chamber 10 and placed on the susceptor 11, and thereafter, the same process as when the wafer W is loaded into the chamber 10 is repeated, and the other wafers W are etched.

  FIG. 2 is a flowchart for explaining a cleaning method of the process apparatus according to the present embodiment.

In FIG. 2, a plasma processing apparatus 1 as a process apparatus carries a wafer W to be processed into a chamber 10 and first conditions defined by the gas flow rate and gas molecular weight of the processing gas, specifically, A processing gas is introduced into the chamber 10 based on the product A ₁ (= Q ₁ × m ₁ ) of the processing gas flow rate Q ₁ and the molecular weight m ₁ , and the surface of the wafer W is physically or chemically etched (plasma processing). Step) (Step S21), the gate valve 32 is opened, the wafer W placed on the susceptor 11 is unloaded from the chamber 10, and the gate valve 32 is further closed.

  Next, before carrying another wafer W to be processed into the chamber 10, a pre-purge gas is introduced into the chamber 10 (gas introduction step). That is, the pre-purge gas (for example, oxygen, argon, or nitrogen, or a mixed gas thereof) different from the processing gas from the shower head 33 is introduced into the chamber 10 based on the second condition guided based on the first condition. The pressure in the chamber 10 is set to a predetermined value by the APC 14 or the like. This makes it possible to select a pre-purge gas that can provide a gas viscous force that can more effectively remove particles.

Here, in order to remove particles remaining in the chamber 10 without being peeled off by the processing gas introduced based on the value of the product A ₁ is the product A _p in Puripajigasu is the product A ₁ value greater than There is a need. Therefore, specifically, CPU 53 calculates a product _A p of the flow rate _{Q p} and the molecular weight _{m p} of Puripajigasu _{(= Q p × m p)} ( calculation step) (step S22), and the product _A p (= Q _p × m _p ) is larger than the product A ₁ of the flow rate Q _{1 of the} processing gas introduced into the chamber 10 when the wafer W is processed and the molecular weight m ₁ , for example, 1.05 times or more of the product A ₁ set the flow rate Q _p of Puripajigasu so that, to control the flow rate of Puripajigasu by transmitting a signal corresponding to the flow rate Q _p set in the flow controller 39 (step S23). Further, the pre-purge gas is introduced into the chamber 10 at the flow rate Q _p set as described above for 1.0 to 10 seconds, and then the introduced pre-purge gas is discharged from the chamber 10. Thereby, the particles in the chamber 10 are removed.

  Further, oxygen gas as a dry cleaning gas is introduced into the chamber 10 from the shower head 33 (step S24), and the pressure in the chamber 10 is set to a predetermined value by controlling the supply amount and exhaust amount of the oxygen gas (step S24). S25). Thereafter, high frequency power is applied from the high frequency power source 52 to the shower head 33 (plasma step) (step S26). As a result, the oxygen gas in the chamber 10 is turned into plasma, and deposits remaining in the chamber 10 after the introduction of the pre-purge gas are removed (ashed) by the plasma.

  Next, high frequency power is applied to the shower head 33 for a predetermined time to convert the oxygen gas in the chamber 10 into plasma, and then the application of high frequency power to the shower head 33 is stopped and the oxygen gas is discharged from the chamber 10. This process ends.

  As described above, according to the present embodiment, from the processing gas introduced into the chamber 10 based on the first condition defined by the gas flow rate and the gas molecular weight used when the wafer W is etched. The wafer W is subjected to plasma processing using the generated plasma, and the pre-purge gas is introduced based on the second condition guided based on the first condition. Therefore, the pre-purge gas introduced based on the second condition Particles can be removed from the chamber 10 by the gas viscous force, and thus generation of particles in the chamber 10 can be prevented.

  In addition, since the inside of the chamber 10 is turned into plasma after introducing the pre-purge gas into the chamber 10, deposits that cause generation of particles can be removed by the plasma generated from the oxygen gas. Generation of particles can be further prevented.

Furthermore, the product A _p of the flow rate Q _p and the molecular weight m _p of Puripajigasu in the second condition is larger than the product A ₁ of the flow rate Q _1, the molecular weight m ₁ of the process gas in the first condition, the second condition Particles can be reliably removed from the chamber 10 by the gas viscous force of the pre-purge gas introduced based on the above.

  In the present embodiment, the pre-purge and the ashing of the deposit in the chamber 10 are performed for each wafer, but the present invention is not limited to this, and the chamber 10 is processed at an arbitrary timing, for example, after processing a predetermined number of wafers. Pre-purge and depot ashing may be performed.

Further, in the present embodiment, CPU 53, the value _{A p} multiplied by the flow rate _{Q p} and the molecular weight _{m p} of Puripajigasu is, a value _{A 1} value greater than, for example, so as to be more than 1.05 times the value _{A 1} While setting the flow rate _{Q p} of Puripajigasu to, not limited to this, the flow rate is calculated based on the calculated values _{a 1,} a predetermined value, for example, ^{1.69 × 10 -1 Pa · m 3} / it may be set flow rate _{Q p} of Puripajigasu by adding the s (100 sccm).

In the present embodiment, a processing gas (for example, a mixed gas composed of C ₄ F ₈ gas, O ₂ gas, and Ar gas at a predetermined flow rate ratio) used when processing the wafer W is a pre-purge gas (for example, oxygen gas). , Argon, nitrogen, or a mixed gas thereof), but is not limited thereto, and may be the same as the pre-purge gas. Thereby, the particles can be easily removed from the chamber 10 without changing the gas introduced into the chamber 10.

  In the present embodiment, the pre-purge gas is different from the dry cleaning gas introduced when ashing the deposit remaining in the chamber 10, but is not limited to this, and is the same as the dry cleaning gas. May be. Thereby, it is possible to remove particles from the chamber 10 more easily without changing the gas introduced into the chamber 10.

  Further, the process apparatus cleaning method according to the present embodiment is applied to the plasma processing apparatus 1, but is not limited to this, and can be applied to all process apparatuses having a chamber.

  In the embodiment described above, the object to be processed in the plasma processing apparatus 1 is the wafer W. However, the object to be processed is not limited to this, and for example, an FPD (Flat Panel Display) including an LCD (Liquid Crystal Display). ) 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 embodiments, and the program code and the storage medium and program storing the program code constitute the present invention. Become.

  Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, and a DVD-RAM. DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM, and the like can be used. Alternatively, the program is supplied by downloading from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like.

  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.

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

  Examples of the present invention will be described below.

  First, in order to prevent scattering of particles when introducing a processing gas or a purge gas in the chamber 10, a processing gas, a purge gas, or the like is carried out before another wafer W is loaded into the chamber 10 of the plasma processing apparatus 1. It is necessary to prevent separation of particles and deposits due to the gas flow.

  Particles adhering to the inside of the chamber 10, for example, the inner wall of the chamber 10 are peeled off from the inner wall of the chamber 10 by receiving a peeling force from the processing gas or the purge gas. The cause of this particle peeling is a force called a gas viscous force acting on the particles, and this gas viscous force is expressed by the following equation as a force proportional to the average flow velocity of the gas.

(Gas density, v _R : Gas average flow velocity, m: Gas molecular weight, r _p : Particle radius)
When the particles adhering to the inner wall of the chamber 10 repeatedly collide with gas molecules, the particles are separated from the inner wall of the chamber 10 by the gas viscous force expressed by the above formula and float again in the chamber 10. The particles floating again in the chamber 10 are accelerated in the gas flow direction. In the above formula, when the gas pressure and the particle radius is assumed to be a constant value, the gas viscous force k _N is proportional to the gas average flow velocity and the gas molecular weight. Therefore, nitrogen, argon, and oxygen having different molecular weights were introduced into the chamber 10 while controlling the flow rates, and particles floating in the chamber 10 were observed with a CCD camera when the gas was introduced at various flow rates. . Specifically, nitrogen, argon, and oxygen were respectively controlled to flow rates as shown in Table 1, and measurements were performed in order from Step 1 to Step 10 in Table 1. The results are shown in Table 1.

First, when argon was introduced into the chamber at 8.45 × 10 ⁻¹ Pa · m ³ / s (500 sccm), particles floating in the chamber 10 were observed (step 1). However, when nitrogen was introduced into the chamber at 500 sccm, similar to argon (step 3), no particles were observed. Furthermore, when argon was again introduced into the chamber at 500 sccm, particles were observed (step 4). This is because even when the gas flow rates of nitrogen and argon are the same, the molecular weights of nitrogen and argon are different, and when nitrogen is introduced, the peel force is reduced as the value A multiplied by the flow rate Q and the molecular weight m decreases. It is considered that (gas viscous force) was reduced, particles were not separated, and particles were not observed.

After that, when nitrogen gas is introduced at 2.5 Pa · m ³ / s (1500 sccm), particles are observed (step 8), and when argon is introduced at 1.7 Pa · m ³ / s (1000 sccm), the particles are observed. Not (step 9). Further, when argon was introduced at 1.7 Pa · m ³ / s (1000 sccm) and oxygen was introduced at 3.38 × 10 ⁻¹ Pa · m ³ / s (200 sccm), particles were observed (step 10). . In step 10, the total flow rate of gas (argon and oxygen) is reduced compared to step 8, but since the value A obtained by multiplying the flow rate Q and the molecular weight m is larger than the value A in step 9, It is thought that it was observed.

  Here, as shown in Table 1, the value A in step 3 is smaller than the value A in steps 1 and 2 before step 3, and the value A in step 6 is the value in steps 4 and 5 before step 6. Although smaller than A and the value A in step 9 is smaller than the value A in steps 7 and 8 prior to step 9, no particles are observed in any of steps 3, 6 and 9.

  Thus, after introducing the gas by setting the gas flow rate and molecular weight so that the value A becomes a predetermined value (steps 1, 2, 4, 5, 7, and 8), the value A becomes smaller than the predetermined value. Thus, it was found that if the gas flow rate and molecular weight were set and the gas was introduced (steps 3, 6 and 9), no particles were generated. This is because when a gas is introduced by setting the flow rate and molecular weight of the gas so that the value A becomes a predetermined value, particles and particles generated by the gas viscous force of the gas are removed from the chamber 10. It was considered that it could be removed reliably.

Therefore, when applying this discussed embodiment of the present invention described above, i.e., the value A _P obtained by multiplying the flow rate and molecular weight of Puripajigasu is, the flow rate values A ₁ and purge gas obtained by multiplying the flow rate and molecular weight of the process gas When the flow rate of the pre-purge gas is controlled so as to be larger than the value A ₂ obtained by multiplying the molecular weight by the molecular weight, when the pre-purge gas is introduced, particles and particles generated due to the gas viscosity force of the pre-purge gas are removed from the chamber 10. It turns out that it can be expected to be removed reliably.

  Next, optimum conditions for dry cleaning (WLDC) for removing deposits deposited in the chamber of the plasma processing apparatus will be described.

  Next, as Example 1, the high frequency power applied to the shower head 33 as the upper electrode is set to 300 W, and the oxygen gas in the chamber 10 is turned into plasma, and then as indicated by 1 to 22 in FIG. A polyimide film was attached to a predetermined position in the chamber 10, and the ashing rate (nm / sec) of each polyimide film was measured. Moreover, as Comparative Example 1 and Comparative Example 2, the ashing rate of each polyimide film when the high-frequency power was set to 500 W and 800 W was measured.

  Next, from the value of the ashing rate of each polyimide film measured as described above, (1) the uniformity of the ashing rate of the polyimide film in all parts (hereinafter simply referred to as “uniformity”), and (2) consumption by plasma 4 to 6 as positions where deposits are likely to occur (parts where a large amount of deposits) are generated with respect to the average ashing rate of the polyimide film attached to positions 1 to 3 and positions 12 to 16 as worries about wear. And the ratio of the average ashing rate of the polyimide film affixed to positions 20 to 22 (hereinafter simply referred to as “ashing efficiency”), and these calculated values are described below for Example 1, Comparative Example 1 and Comparative Example 2. Table 2 is shown.

As Example 2, the ashing rate of the polyimide film was measured when the amount of oxygen gas introduced into the chamber 10 was 1.4 Pa · m ³ / s (800 sccm). Further, Comparative Example 3 and Comparative Example 4 as the oxygen gas amount ashing rate of the polyimide film was respectively measured when a ^{2.0Pa · m 3 / s (1200sccm} ) and ^{2.7Pa · m 3 / s (1600sccm} ), these measured ashing rate Thus, the uniformity and ashing efficiency were calculated for each of Example 2, Comparative Example 3 and Comparative Example 4, and are summarized in Table 3 shown below.

Further, as Example 3, the ashing rate of the polyimide film was measured when the pressure in the chamber 10 was 2.7 × 10 ⁻² kPa (200 mTorr). Further, as Comparative Example 5 and Comparative Example 6, the chamber 10 The ashing rates of the polyimide films were measured when the internal pressure was 5.3 × 10 ⁻² kPa (400 mTorr) and 8.0 × 10 ⁻² kPa (600 mTorr), respectively. Thus, the uniformity and ashing efficiency were calculated for each of Example 3, Comparative Example 5 and Comparative Example 6, and are summarized in Table 4 shown below.

  Here, in the case of WLDC (Wafer-less Dry Cleaning), it is preferable to ash many depots at a site where depots are likely to occur from the viewpoint of suppressing the occurrence of depots, and therefore, the average ashing rate at the site where depots are likely to occur is large. From the viewpoint of suppressing consumption, it is preferable that the average ashing rate at the portion where consumption is a concern is small, that is, the condition for increasing the ashing efficiency is preferable as the execution condition of WLDC. In each table, “average ashing rate of all parts” and “uniformity of ashing rate of all parts” are reference values for capturing the ashing rate of the entire chamber 10.

From the viewpoint of ashing efficiency described above, the optimum conditions of WLDC were examined based on each table, and it was found from Table 4 that the pressure in the chamber 10 is preferably 2.7 × 10 ⁻² kPa corresponding to Example 3. It was. From the viewpoint of ashing efficiency, the high-frequency power is preferably 500 W corresponding to Comparative Example 1 from Table 2, but at this time, the average ashing rate at which the consumption is a concern is as high as 1.2 [nm / sec]. From the viewpoint of suppressing wear, it is not preferable as the optimum condition for WLDC. Therefore, from the viewpoint of suppressing consumption, the optimum conditions for WLDC were examined, and it was found from Table 1 that 300 W is preferable for the high-frequency power.

From the viewpoint of ashing efficiency, the amount of oxygen gas is preferably 2.7 Pa · m ³ / s corresponding to Comparative Example 4 from Table 3. However, in Table 3, since there is no significant difference in the ashing efficiency between Example 2, Comparative Example 3 and Comparative Example 4, the optimum conditions for WLDC are either Example 2, Comparative Example 3 or Comparative Example 4. The corresponding oxygen gas amount may be used. However, since the power is small at the above-described high frequency power of 300 W as the optimum condition of WLDC, it is preferable that the amount of oxygen gas is small from the viewpoint of plasmatizing efficiency. Therefore, the oxygen gas amount is preferably 1.4 Pa · m ³ / s corresponding to Example 2.

Next, since it is preferable that the pressure in the chamber 10 is low as described above, in order to find a more optimal pressure in the chamber 10, the oxygen gas introduced into the chamber 10 in each chamber part shown in FIG. When the pressure in the chamber 10 is 2.7 × 10 ⁻² kPa (200 mTorr) or less under the condition that the flow rate is 1.4 Pa · m ³ / s (800 sccm) and the high frequency power applied to the shower head is 300 W. The ashing rate was measured, and the results are shown in FIG. FIG. 5 shows the results of calculating the uniformity and ashing efficiency from the measurement results of FIG.

From the result of FIG. 5, it can be seen that the pressure in the chamber 10 is 1.3 × 10 ^{−2 to} 4.0 × 10 ⁻² kPa (100 to 300 mTorr), and the ashing efficiency exhibits a better value. It was. Therefore, it turned out that it is more preferable that the pressure in the chamber 10 is 1.3 * 10 ^<-2 > -4.0 * 10 ^{< -2} > kPa.

From the above results, as the optimum conditions for dry cleaning (WLDC), the high-frequency power applied to the shower head 33 is 200 to 400 W, and the gas flow rate introduced into the chamber 10 is 1.4 Pa · m ³ / s (800 sccm). ) As described above, when the pressure in the chamber 10 is 1.3 × 10 ^{−2 to} 4.0 × 10 ⁻² kPa (100 to 300 mTorr), the high frequency power applied to the shower head 33 is preferably 300 W, the chamber 10 When the flow rate of oxygen gas introduced into the chamber is 1.4 Pa · m ³ / s and the pressure in the chamber 10 is 1.3 × 10 ^{−2 to} 2.7 × 10 ⁻² kPa, It has been found that deposits can be removed without damage.

It is sectional drawing which shows schematically the structure of the plasma processing apparatus with which the cleaning method of the process apparatus which concerns on embodiment of this invention is applied. It is a flowchart explaining the washing | cleaning method of the process apparatus which concerns on this Embodiment. It is a figure explaining the position which affixed the polyimide film in the chamber 10 of FIG. It is a figure which shows the result of having measured the ashing rate when the pressure in a chamber shall be 2.7x10 < ^-2 > kPa or less. It is a figure which shows the result of having calculated uniformity and ashing efficiency from the measurement result of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 10 Chamber 33 Shower head 39 Flow control apparatus 52 High frequency power supply 53 CPU

Claims (9)

A cleaning method for a process apparatus including a processing chamber for plasma processing a workpiece,
A plasma processing step of performing plasma processing on the object to be processed using plasma generated from a gas introduced based on at least a first condition defined by a gas flow rate and a gas molecular weight;
And a gas introduction step for introducing a gas based on a second condition derived based on the first condition.   2. The process apparatus cleaning method according to claim 1, further comprising a plasma step for converting the inside of the processing chamber into a plasma after the gas introduction step.   3. The process apparatus cleaning method according to claim 1, wherein the gas introduced in the plasma treatment step is the same as the gas in the gas introduction step.   3. The process apparatus cleaning method according to claim 1, wherein the gas in the plasma treatment step is different from the gas in the gas introduction step.   3. The process apparatus cleaning method according to claim 1, wherein the gas in the gas introduction step is the same as the gas in the plasma step. Product A gas flow rate and the gas molecular weight in the second condition, according to any one of claims 1-5, characterized in that greater than the product A _x of the gas flow rate and gas molecular weight in the first condition Process equipment cleaning method. In the plasma step, the gas flow rate introduced into the processing chamber is 1.4 Pa · m ³ / s (800 sccm) or more, and the pressure in the processing chamber is 1.3 × 10 ^{−2 to} 4.0 × 10. The process apparatus cleaning method according to claim 2, wherein ⁻² kPa (100 to 300 mTorr) and high-frequency power applied in the processing chamber is 200 to 400 W. 8. A program for causing a computer to execute a cleaning method for a process apparatus including a processing chamber for plasma-processing an object to be processed,
A plasma processing module for plasma-treating the object to be processed using plasma generated from a gas introduced based on at least a first condition defined by a gas flow rate and a gas molecular weight;
A gas introduction module for introducing a gas based on a second condition guided based on the first condition;
A program characterized in that the product A of the gas flow rate and the gas molecular weight in the second condition is larger than the product A _x of the gas flow rate and the gas molecular weight in the first condition. A storage medium storing a computer-readable program for causing a computer to execute a cleaning method for a process apparatus including a processing chamber for plasma-processing an object to be processed.
A plasma processing module for plasma-treating the object to be processed using plasma generated from a gas introduced based on at least a first condition defined by a gas flow rate and a gas molecular weight;
A gas introduction module for introducing a gas based on a second condition guided based on the first condition;
The storage medium characterized in that the product A of the gas flow rate and the gas molecular weight in the second condition is larger than the product A _x of the gas flow rate and the gas molecular weight in the first condition.

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