JP4544459B2 - Particle detection method and particle detection program - Google Patents

Description

  The present invention relates to a particle detection method and a particle detection program, and more particularly to a particle detection method for detecting the number of particles carried by an air current.

  Usually, in a substrate processing apparatus having a processing chamber for performing arbitrary processing on a semiconductor wafer (hereinafter referred to as “wafer”) as a substrate, particles caused by contact between the wafer and a mounting table on which the wafer is mounted, for example, aluminum Metal fragments and reaction products resulting from the reaction of the processing gas, such as fluorocarbon polymers, are generated.

  In order for these particles to adhere to the wafer and reduce the quality of the semiconductor device formed on the surface of the wafer, in the substrate processing apparatus, in order to keep the particle size and number of particles in the processing chamber below a certain value, When the particle diameter and number of particles are detected and the particle diameter and number become larger than a certain value, the substrate processing apparatus is stopped, and cleaning of the processing chamber and replacement of components are performed.

  As a method for detecting such a particle, a method of measuring scattered light in a particle monitor provided in the middle of an exhaust passage for discharging particles and gas in a processing chamber is conventionally known.

  In this method of measuring scattered light, a light beam (flux) formed in a sheet shape (band shape) is passed through an airflow flowing in an exhaust passage, and particles contained in the airflow pass through the light beam. The intensity of the generated scattered light is measured by a sensor arranged opposite to the exhaust flow path, and the particle size of the particles is calculated according to the measured scattered light intensity (see, for example, Patent Document 1).

  Here, since the particles pass in front of the sensor as time elapses, the scattered light intensity measured by the sensor is initially the time as shown in the scattered light intensity of the particles Pf and Ps shown in FIG. It gradually increases as time passes, and when it reaches an extreme value, it gradually decreases thereafter. In order to accurately detect the particle size of the particles, it is preferable to continuously measure the scattered light intensity as time passes. In this case, the amount of data to be measured becomes enormous and the data is processed. Takes a long time. Further, although the change in scattered light intensity may be approximated by a Gaussian curve or the like based on a plurality of measurement data, it still takes time for curve fitting.

  Therefore, in recent years, a detection method in which the measurement time is divided into measurement periods at predetermined time intervals and the scattered light intensity is measured (discretely) at predetermined timings in each measurement period (T1, T2,..., T5 in FIG. 7). Is running. In this detection method, the maximum scattered light intensity in the measurement period is selected for each measurement period, and the selected maximum scattered light intensity is stored in a memory or the like. Further, in this detection method, when the selected maximum scattered light intensity exceeds a predetermined threshold for each predetermined period, it is determined that one particle has passed, and the particle size of the particles that have passed based on the maximum scattered light intensity is determined. Is calculated. According to this detection method, since only one maximum scattered light intensity is selected and stored in each measurement period, the amount of data can be reduced, and the time required for data processing can be reduced.

Further, according to this detection method, for example, one maximum scattered light intensity PfI is selected for a particle that passes in front of the sensor within one predetermined period (T1) like the particle Pf in FIG. Therefore, the number of particles passing in front of the sensor can be accurately measured.
JP 2000-146819 A

However, in the detection method described above, for particles that pass in front of the sensor over a plurality of predetermined periods (T2 to T5), that is, low-speed particles, like the particles Ps in FIG. Since four maximum scattered light intensities PsI _{1 to} PsI ₄ are selected corresponding to T5, one particle Ps actually passes in front of the sensor even though it only passes in front of the sensor. There is a problem that the number of particles is determined to be four at the maximum, that is, there is a problem that the number of low-speed particles cannot be accurately detected.

  When the number of particles cannot be accurately detected, unnecessary cleaning of the processing chamber or replacement of components may be performed, which causes a problem of reducing the operating efficiency of the substrate processing apparatus.

  An object of the present invention is to provide a particle detection method and a particle detection program capable of accurately detecting the number of low-speed particles.

  In order to achieve the above object, the particle detection method according to claim 1 is a particle detection method for detecting particles carried by an air current, wherein the light emitted to the air current is scattered by the particles. A scattered light intensity measuring step for measuring the intensity of light by a light receiving means at a predetermined timing, and a measurement time for measuring the scattered light intensity is divided into measurement periods for each predetermined time, and the measured scattered light in each measurement period The maximum intensity measurement timing selection step for selecting the measurement timing at which the maximum scattered light intensity is measured among the intensities, and the number of particles that have passed in front of the light receiving means based on the measurement timing selected in each measurement period. And a particle passing number counting step for counting.

  The particle detection method according to claim 2 is the particle detection method according to claim 1, wherein the particle passing number counting step is configured such that, in each of the measurement periods, the selected measurement timing is the start and end of each of the measurement periods. In any case, it is determined that the particle does not pass in front of the light receiving means.

  The particle detection method according to claim 3 is the particle detection method according to claim 1 or 2, wherein the scattered light intensity measurement step does not measure the intensity of the scattered light smaller than a predetermined threshold value.

  The particle detection method according to claim 4 is the particle detection method according to any one of claims 1 to 3, wherein the maximum intensity measurement timing selection step selects the maximum scattered light intensity together with the measurement timing. It is characterized by that.

  The particle detection method according to claim 5 is a particle detection method according to any one of claims 1 to 4, wherein particle size calculation is performed to calculate the particle size of the particles according to the maximum scattered light intensity. Furthermore, it is characterized by having.

  The particle detection method according to claim 6 is the particle detection method according to any one of claims 1 to 5, wherein the scattered light intensity measurement step is applied to the air flow in a processing chamber of a substrate processing apparatus. It is characterized by measuring the intensity of scattered light.

  The particle detection method according to claim 7 is the particle detection method according to any one of claims 1 to 5, wherein the scattered light intensity measurement step includes an exhaust flow path connected to a processing chamber of the substrate processing apparatus. The intensity of the scattered light of the light irradiated on the airflow inside is measured.

  In order to achieve the above object, a particle detection program according to claim 8 is a particle detection program for causing a computer to execute a particle detection method for detecting particles carried by an air current, wherein light applied to the air current is detected. A scattered light intensity measurement module that measures the intensity of scattered light generated by being scattered by the particles at a predetermined timing by a light receiving means, and a measurement time for measuring the scattered light intensity is divided into measurement periods for each predetermined time, and each measurement is performed. A maximum intensity measurement timing selection module that selects a measurement timing at which the maximum scattered light intensity is measured among the measured scattered light intensities in a period, and based on the measurement timing selected in each measurement period, A party that counts the number of particles that have passed Particle detection program and having a cycle passing number counting module.

  According to the particle detection method according to claim 1 and the particle detection program according to claim 8, based on the measurement timing at which the maximum scattered light intensity is measured among the scattered light intensities measured in each measurement period, Since the number of particles passing through is counted, the number of particles is not counted based only on the scattered light intensity in each measurement period. Therefore, it is possible to accurately detect the number of low-speed particles passing in front of the sensor over a plurality of measurement periods.

  According to the particle detection method of the second aspect, in each measurement period, when the measurement timing at which the maximum scattered light intensity is measured corresponds to either the start period or the end period in each measurement period, the particle is in front of the light receiving unit. Therefore, it is possible to accurately detect the number of low-speed particles that pass in front of the sensor over a plurality of measurement periods.

  According to the particle detection method of the third aspect, since the intensity of the scattered light smaller than the predetermined threshold is not measured, it is possible to avoid measuring the intensity of light other than the scattered light generated by the particle, The number can be detected more accurately.

  According to the particle detection method of claim 4, since the maximum scattered light intensity is selected together with the measurement timing at which the maximum scattered light intensity is measured, the correlation between the measurement timing and the maximum scattered light intensity is facilitated. be able to.

  According to the particle detection method of the fifth aspect, since the particle diameter of the particle is calculated according to the maximum scattered light intensity, it is possible to accurately calculate the size of the particle passing in front of the light receiving means.

  According to the particle detection method of the sixth aspect, the intensity of the scattered light of the light irradiated on the airflow in the processing chamber of the substrate processing apparatus is measured. Particles in the processing chamber degrade the quality of the semiconductor device. Therefore, it is possible to directly detect the number of particles that cause the quality degradation of the semiconductor device, and to reliably prevent the quality degradation of the semiconductor device.

  According to the particle detection method of the seventh aspect, the intensity of the scattered light of the light irradiated to the airflow in the exhaust passage connected to the processing chamber of the substrate processing apparatus is measured. In the substrate processing apparatus, particles in the processing chamber are purged by the exhaust passage prior to pressure reduction in the processing chamber. Therefore, the particles can be easily detected.

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

  First, a substrate processing apparatus to which the particle detection method according to the present embodiment is applied will be described.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a substrate processing apparatus to which the particle detection method according to the present embodiment is applied.

  In FIG. 1, a substrate processing apparatus 2 configured as an etching processing apparatus for performing an etching process on a semiconductor wafer W has a cylindrical chamber 10 made of metal, for example, aluminum or stainless steel. For example, a cylindrical susceptor 11 is arranged as a stage on which a semiconductor wafer W having a diameter of 300 mm is placed.

  Between the side wall of the chamber 10 and the susceptor 11, an exhaust path 12 that functions as a flow path for discharging the gas above the susceptor 11 to the outside of the chamber 10 is formed. An annular baffle plate 13 is arranged in the middle of the exhaust passage 12, and the space downstream of the baffle plate 13 of the exhaust passage 12 is an automatic butterfly valve via an exhaust pipe 50 having a diameter of, for example, 150 mm. A pressure control valve (hereinafter referred to as “APC”) 14 is communicated. 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. The exhaust flow path constituted by the exhaust pipe 50, the APC 14, the TMP 15 and the DP 16 is hereinafter referred to as a “main exhaust line”. The main exhaust line not only controls the pressure in the chamber 10 by the APC 14, but also by the TMP 15 and the DP 16. The gas and particles in the chamber 10 are exhausted (purged), and the pressure in the chamber 10 is reduced to a nearly vacuum state. In the exhaust pipe 50 between the exhaust passage 12 and the APC 14 in the main exhaust line, a particle monitor 40 described later is disposed, and the particle monitor 40 is connected to a particle counter 41.

  The particle monitor 40 allows the light flux to pass through the exhaust flow flowing in the exhaust pipe 50, measures the intensity of the scattered light generated when the particles contained in the airflow penetrate the light flux, and measures the scattered light intensity thus measured. Are transmitted to the particle counter 41. The particle counter 41 counts the particle size and the number of particles P passing in front of a light receiving sensor 44 described later based on the transmitted scattered light intensity and the like by a particle detection method described later.

  A high frequency power source 18 is connected to the susceptor 11 via a matching unit 19, and the high frequency power source 18 applies a predetermined high frequency power to the susceptor 11. Thereby, the susceptor 11 functions as a lower electrode. The matching unit 19 reduces the reflection of the high frequency power from the susceptor 11 to maximize the incidence efficiency of the high frequency power on the susceptor 11.

  A disk-shaped electrode plate 20 made of a conductive film for adsorbing the semiconductor 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 semiconductor wafer W is adsorbed 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 supply 22. An annular focus ring 24 made of silicon (Si) or the like is disposed above the susceptor 11, and the focus ring 24 converges the plasma generated above the susceptor 11 toward the semiconductor 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 via a pipe 26, and the processing temperature of the semiconductor wafer W on the susceptor 11 depends on the temperature of the coolant. Be controlled.

  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 semiconductor wafer W is adsorbed (hereinafter referred to as “adsorption surface”). These heat transfer gas supply holes 27 and the like are connected to a heat transfer gas supply unit 29 via a heat transfer gas supply line 28 arranged inside the susceptor 11, and the heat transfer gas supply unit 29 is a heat transfer gas, for example, , He gas is supplied to the gap between the adsorption surface and the back surface of the semiconductor wafer W. The heat transfer gas supply unit 29 is also configured to be able to evacuate the gap between the adsorption surface and the back surface of the semiconductor wafer W.

  A plurality of pusher pins 30 as lift pins that can protrude from the upper surface of the susceptor 11 are arranged on the suction surface. These pusher pins 30 move so as to be able to protrude with respect to the suction surface when the rotational motion of a motor (not shown) is converted into linear motion by a ball screw or the like. When the semiconductor wafer W is sucked and held on the suction surface, the pusher pin 30 is accommodated in the susceptor 11, and when the semiconductor wafer W subjected to the etching process is unloaded from the chamber 10, the pusher pin 30 protrudes from the upper surface of the susceptor 11. The semiconductor wafer W is separated from the susceptor 11 and lifted upward.

  A shower head 33 is disposed on the ceiling of the chamber 10. Since the shower head 33 is grounded (grounded), the shower head 33 functions as a ground 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. An MFC (Mass Flow Controller) 39 is disposed in the middle of the processing gas introduction pipe 38. The MFC 39 supplies a predetermined gas, for example, a processing gas or N ₂ gas to the chamber 10 via the buffer chamber 37 and controls the flow rate of the gas to cooperate with the APC 14 described above. And control to a desired value. Here, the inter-electrode distance D between the susceptor 11 and the shower head 33 is set to 35 ± 1 mm or more, for example.

  A gate valve 5 for opening and closing the loading / unloading port 31 for the semiconductor wafer W is attached to the side wall of the chamber 10. In the chamber 10 of the substrate processing apparatus 2, as described above, high frequency power is applied to the susceptor 11, and the applied high frequency power causes a high density from the processing gas in the space S between the susceptor 11 and the shower head 33. Plasma is generated and ions and radicals are generated.

In the substrate processing apparatus 2, during the etching process, first, the gate valve 5 is opened, and the semiconductor wafer W to be processed is loaded into the chamber 10 and placed on the susceptor 11. Then, after purging particles in the chamber 10 by this exhaust line, 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 to a predetermined amount. The flow rate and the flow rate ratio are introduced into the chamber 10, and the pressure in the chamber 10 is set to a predetermined value by the APC 14 or the like. Further, high frequency power is applied to the susceptor 11 from the high frequency power source 18, and a DC voltage is applied to the electrode plate 20 from the DC power source 22 to adsorb the semiconductor wafer W onto the susceptor 11. Then, the processing gas discharged from the shower head 33 is turned into plasma as described above. Radicals and ions generated by this plasma are focused on the surface of the semiconductor wafer W by the focus ring 24, and the surface of the semiconductor wafer W is physically or chemically etched.

  FIG. 2 is a diagram showing a schematic configuration of the particle monitor in FIG.

  In FIG. 2, a particle monitor 40 includes 10 laser beams L1, L2,..., L10 arranged in a one-dimensional manner, and 10 in-line shapes emitted from the laser light source 42. , L10 are combined into a single band-like (band width direction d) light beam L0 as a whole, and the light beam L0 is substantially the same as the exhaust flow A flowing in the exhaust pipe 50 in the width direction d. When the projection optical system 43 that irradiates the exhaust stream A so as to penetrate perpendicularly, the light receiving sensor 44 that detects the intensity of light, and the particles P contained in the exhaust stream A pass through the light beam L0, And a detection optical system 45 that guides the scattered light K scattered in a predetermined angle (an angle other than an integral multiple of 180 °) to the irradiation direction of the light beam L0 to the light receiving sensor 44.

  The projection optical system 43 uses a laser light source so that the light intensity of the strip-shaped light beam L0 is substantially uniform in the exhaust stream passage region R where the light beam L0 intersects the exhaust stream A in the strip width direction d. .., L10 are partially overlapped with each other. Specifically, each of the ten light beams L1, L2,..., L10 passes through different regions in a single lens that forms part of the projection optical system 43, and each light beam is a light beam with a small opening angle. Further, by adjusting the distance between the laser light source 42 and the exhaust flow passage region R and the distance between the single lens and the exhaust flow passage region R, the light beams L1, L2,. The projection optical system 43 is configured so that a part of the projections overlap each other.

  Further, the detection optical system 45 is configured to converge the scattered light K generated from the exhaust flow passage region R onto the light receiving surface of the light receiving sensor 44, and the light receiving sensor 44 has particles P in the exhaust flow A set in advance. In each measurement period in which the measurement time is measured every predetermined time, the scattered light intensity of the scattered light K is measured at each predetermined timing, and the measured scattered light intensity and the measurement timing of the scattered light intensity ( (Hereinafter referred to as “time information”) is transmitted to the particle counter 41 as scattered light intensity data.

  Returning to FIG. 1, the particle counter 41 calculates the scattered light intensity data of the maximum scattered light intensity (hereinafter referred to as “maximum scattered light intensity data” from the scattered light intensity data for each measurement period transmitted from the light receiving sensor 44. Similarly to the scattered light intensity data, the scattered light intensity data also includes the scattered light intensity and time information.) The maximum scattered light intensity selection unit 46 for selecting), and the memory 47 for storing the maximum scattered light intensity data The particle detector 48 calculates the particle size of the particles P based on the scattered light intensity of the maximum scattered light intensity data stored in the memory 47 and counts the number of particles P, and the particles calculated by the particle detector 48. And a display unit 49 for displaying the particle size and number of P.

  As the maximum scattered light intensity data, the maximum scattered light intensity is selected together with the time information corresponding to the maximum scattered light intensity, so that the time information corresponding to the maximum scattered light intensity can be easily correlated with the maximum scattered light intensity. It is to do.

  The maximum scattered light intensity selection unit 46 is an arithmetic circuit such as a CPU or FPGA (Field Programmable Gate Array), and is an internal memory (not shown) that temporarily stores scattered light intensity data in each predetermined period transmitted from the light receiving sensor 44. When the scattered light intensity data for one predetermined period is stored in the internal memory, the maximum scattered light intensity data is selected from the stored scattered light intensity data. That is, the maximum scattered light intensity selection unit 46 selects one maximum scattered light intensity data every predetermined period.

  The memory 47 is a storage medium capable of writing and erasing data, such as a RAM or an HDD, and stores the maximum scattered light intensity data for each predetermined period selected by the maximum scattered light intensity selection unit 46. Here, since the maximum scattered light intensity selection unit 46 selects only one maximum scattered light intensity data for each predetermined period, the memory 47 has a number of maximum scattered light intensity data corresponding to the quotient obtained by dividing the measurement time by the predetermined time. Is stored.

  The particle detector 48 is also an arithmetic circuit such as a CPU or FPGA, and the maximum scattering of each predetermined period stored in the memory 47 in accordance with a program or circuit configuration for executing a particle detection method according to the present embodiment to be described later. The particle size of the particle P is calculated based on the scattered light intensity of the light intensity data, and the number is counted.

  In the particle counter 41 described above, the maximum scattered light intensity selection unit 46 and the particle detection unit 48 are configured by independent calculation circuits. However, the maximum scattered light intensity selection unit 46 and the particle detection unit 48 have one calculation circuit. It may be constituted by.

  Next, the particle detection method according to the present embodiment will be described.

  In the conventional detection method, the number of particles is detected based only on the maximum scattered light intensity, but in the particle detection method according to the present embodiment, the number of particles is based on time information as well as the maximum scattered light intensity. Detected. That is, the number of particles P passing in front of the light receiving sensor 44 is counted based on the time information of the maximum scattered light intensity data for each predetermined period.

  Specifically, in each measurement period, when the time information of the maximum scattered light intensity data corresponds to either the start or end of each measurement period, the particle P is not passing in front of the light receiving sensor 44. judge. More specifically, as shown in FIG. 3, when the scattered light intensity of the particles P passing in front of the light receiving sensor 44 is measured over a plurality of measurement periods T1 to T8, each measurement period Ti (i = 1). , 2,,, 8) of the maximum scattered light intensity data Pi (where each Pi is composed of scattered light intensity Ii and time information ti), the scattered light intensity Ii is a predetermined threshold (in the figure). Since the time information t2 and t3 of the maximum scattered light intensity data P2 and P3 correspond to the final period in each measurement period T2 and T3, the maximum scattered light intensity data P2 to P7 exceeding the threshold value of the threshold value) are measured in each measurement period T2 and T3. Since it is determined that the particle P has not passed in front of the light receiving sensor 44, and the time information t5 to t7 of the maximum scattered light intensity data P5 to P7 corresponds to the beginning of each measurement period T5 to T7, each measurement In the period T5 to T7, it is determined that the particle P has not passed in front of the light receiving sensor 44, that is, the measurement period corresponding to the maximum scattered light intensity data P4 whose time information does not correspond to either the start or end of the measurement period. At T4, it is determined that one particle P has passed in front of the light receiving sensor 44.

  In the present embodiment, since the light receiving sensor 44 is arranged so as to be directed toward the center of the exhaust pipe 50, the maximum scattered light intensity detected by the light receiving sensor 44 is the particle P flowing through the center of the exhaust pipe 50. This is due to Therefore, in the present embodiment, the case where it is determined that the particle P has passed in front of the light receiving sensor 44 is the case where the particle P has passed through the central portion of the exhaust pipe 50, and the particle P is in front of the light receiving sensor 44. The case where it is determined that the gas does not pass through the exhaust pipe 50 includes a case where the particle P does not pass through the central portion of the exhaust pipe 50 and passes through a portion other than the central portion of the exhaust pipe 50.

  Here, in the present embodiment, for example, when the scattered light intensity is measured 96 times in each measurement period and each measurement timing corresponds to each count number starting from 0, the time information t2 and t3 is the count number. 95 and the time information t5 to t7 corresponds to the count number 0, so that it is determined that the particle P does not pass in front of the light receiving sensor 44 in each measurement period T2, T3, T5 to T7. It is determined that one particle P has passed in front of the light receiving sensor 44 in the measurement period T4 corresponding to the maximum scattered light intensity data P4 whose information t4 does not correspond to the count number 0 or 95.

  Thereby, the number of particles P passing in front of the light receiving sensor 44 over a plurality of measurement periods can be accurately counted.

  In the present embodiment described above, when the time information corresponds to the count number 0 or 95, it is determined that the particle P does not pass in front of the light receiving sensor 44. However, the count number used for the determination is 0. Or it is not restricted to 95. For example, a predetermined width may be set for the number of counts used for the determination in consideration of the influence of light noise received by the light receiving sensor 44. Specifically, when the time information corresponds to one of the count numbers 0 to 10 or 85 to 95, it may be determined that the particle P has not passed in front of the light receiving sensor 44.

  FIG. 4 is a flowchart of the particle detection method according to the present embodiment.

  In FIG. 4, first, the main exhaust line purges particles and the like in the chamber 10, and the light receiving sensor 44 measures the scattered light intensity at each predetermined timing in each measurement period (step S41), and the measured scattering is performed. The light intensity and the time information of the scattered light intensity are transmitted to the particle counter 41 as scattered light intensity data. At this time, the light receiving sensor 44 does not measure scattered light intensity smaller than a predetermined threshold. As a result, it is possible to avoid measuring the intensity of light other than the scattered light generated by the particles P, for example, the light intensity caused by stray light or plasma fluctuations in the chamber 10.

  Next, when the internal memory stores the scattered light intensity data for one predetermined period, the maximum scattered light intensity selection unit 46 selects the maximum scattered light intensity data Pi from the stored scattered light intensity data (step 42). The memory 47 stores the maximum scattered light intensity data Pi.

  In subsequent step 43, it is determined whether or not a preset measurement time has elapsed. If the measurement time has not elapsed, the process returns to step S41, and if the measurement time has elapsed, the process proceeds to step S44.

  Next, when the time information ti of the maximum scattered light intensity data Pi in each measurement period corresponds to the count number 0 or 95, the particle detector 48 receives the particles P in the measurement period corresponding to the maximum scattered light intensity data Pi. When it is determined that it has not passed in front of the sensor 44 and does not correspond to the count number 0 or 95, it is determined that one particle P has passed in front of the light receiving sensor 44 in the measurement period corresponding to the maximum scattered light intensity data Pi. Thus, the number of particles P passing in front of the light receiving sensor 44 is counted (step S44), and the scattered light intensity Ii corresponding to the time information ti of the particle P determined to have passed in front of the light receiving sensor 44 is obtained. Based on this, the particle size of the particle P is calculated (step S45). Specifically, the particle diameter corresponding to the scattered light intensity Ii is read from a previously prepared table showing the correlation between particle diameter and emission intensity. Thereby, the size of the particle P passing in front of the light receiving sensor 44 can be accurately calculated.

  Next, the particle detection unit 48 transmits the counted number of particles P and the calculated particle size of the particles P to the display unit 49, and the display unit 49 displays the number and particle size of the transmitted particles P ( Step S46), the process is terminated.

  According to the particle detection method according to the present embodiment described above, the number of particles P that have passed in front of the light receiving sensor 44 is counted based on the time information of the maximum scattered light intensity data in each measurement period. The number of particles P is not counted based only on the maximum scattered light intensity during the measurement period. Specifically, in each measurement period, when the time information of the maximum scattered light intensity data corresponds to either the start or end of each measurement period, the particle P is not passing in front of the light receiving sensor 44. Since the determination is made, the number of low-speed particles P passing in front of the sensor over a plurality of measurement periods can be accurately counted.

  In the above-described embodiment, the case where one particle P passes in front of the light receiving sensor 44 within the measurement time and the scattered light is not superimposed has been described, but the particle detection method according to the present embodiment is within the measurement time. Further, the present invention can be applied to a case where a plurality of particles P pass in front of the light receiving sensor 44, that is, a case where scattered light is superimposed.

  FIG. 5 is a graph showing a temporal change in scattered light intensity when scattered light caused by two particles P is superimposed, and a relatively high speed particle P passes in front of the light receiving sensor 44 in a predetermined period T3. The case where the relatively low speed particle P passes in front of the light receiving sensor 44 in the predetermined period T5 is shown.

  In FIG. 5, when the particle detection method according to the present embodiment is applied, the scattered light intensity Ii among the maximum scattered light intensity data in each measurement period Ti (i = 1, 2,..., 8). Since the time information t1 and t2 of the maximum scattered light intensity data P1 and P2 corresponds to the end of each of the measurement periods T1 and T2 with respect to the maximum scattered light intensity data P1 to P7 that exceeds a predetermined threshold, the measurement periods T1 and T2 It is determined that the particle P has not passed in front of the light receiving sensor 44, and the time information t4, t6, t7 of the maximum scattered light intensity data P4, P6, P7 corresponds to the beginning of each measurement period T4, T6, T7. Therefore, in each measurement period T4, T6, T7, it is determined that the particle P does not pass in front of the light receiving sensor 44, that is, the time information Ti is the start of the measurement period. It is determined that one particle P has passed in front of the light receiving sensor 44 in each of the measurement periods T3 and T5 corresponding to the maximum scattered light intensity data P3 and P5 that does not correspond to any of the last period. It is determined that two particles P have passed.

As described above, according to the particle detection method according to the present embodiment, even when a plurality of particles P pass in front of the light receiving sensor 44 within the measurement time, the particles P that pass in front of the light receiving sensor 44 are detected. In the present embodiment described above, the scattered light intensity of the light beam L0 irradiated to the exhaust flow A in the exhaust pipe 50 of the exhaust line is measured as described above. In the substrate processing apparatus 2, the particles P and the like in the chamber 10 are purged by the main exhaust line before the pressure in the chamber 10 is reduced. Therefore, the particle P can be easily detected.

  Note that the location where the scattered light intensity is measured is not limited to the main exhaust line, and may be any location as long as the particles P are transported by the air current. For example, the substrate processing apparatus 2 may include the exhaust path 12 described above. A particle monitor disposed in another exhaust pipe having a roughing line composed of another exhaust pipe communicating with a space downstream from the baffle plate 13 and the DP 16 and a valve disposed in the middle of the other exhaust pipe. Thus, the intensity of the scattered light generated in the exhaust flow flowing in another exhaust pipe may be measured. In this case, the particles P and the like in the chamber 10 are purged by the roughing line prior to the decompression in the chamber 10. Therefore, the particle P can be easily detected.

  Alternatively, the light beam L0 may be irradiated into the chamber 10 through a window provided on the side wall of the chamber 10, and the scattered light intensity of the light beam L0 may be measured. Here, the particles P in the chamber 10 deteriorate the quality of the semiconductor device. Therefore, it is possible to detect the number of particles P, which is a direct cause of the deterioration of the quality of the semiconductor device, and to reliably prevent the deterioration of the quality of the semiconductor device.

  The substrate processing apparatus to which the particle detection method according to the present embodiment described above is applied is an etching processing apparatus, but the substrate processing apparatus to which the particle detection method is applied is not limited to this, for example, a coating and developing apparatus. Further, it may be a substrate cleaning apparatus, a heat treatment apparatus, an etching apparatus, a film forming apparatus, or the like.

  Further, the above-described substrate processing apparatus controls the operation of the substrate processing apparatus according to the detected particle diameter and number of particles P. For example, the number of particles P having a particle diameter exceeding a predetermined size is predetermined. There may be provided an operation control device for stopping the operation of the substrate processing apparatus when the number of the substrate processing apparatuses becomes larger than the number. As a result, it is possible to prevent deterioration of the quality of the semiconductor device.

  The particle detection method according to the present embodiment described above is applied to the substrate processing apparatus, but the apparatus to which the particle detection method is applied is not limited to this. For example, the particle detection method is connected to the substrate processing apparatus and is in a reduced pressure or vacuum atmosphere. In this case, the present invention may be applied to detection of particles in a transfer chamber in which the semiconductor wafer W is transferred into and out of the substrate processing apparatus. In this case, the scattered light intensity is preferably measured in the transfer chamber or an exhaust pipe connected to the transfer chamber.

  Further, a substrate processing system having a substrate processing apparatus and a transfer chamber to which the particle detection method according to the present embodiment is applied has a frog-leg type transfer arm for transferring a semiconductor wafer W, as shown in FIG. A cluster type substrate processing system (FIG. 6A) in which a plurality of substrate processing apparatuses are arranged substantially radially around the transfer chamber, and a transfer chamber incorporating the substrate processing apparatus and a scalar type transfer arm. A parallel type substrate processing system (FIG. 6B) in which two process ships are arranged in parallel to each other, and a transfer having a double arm type transfer arm composed of two scalar type transfer arms. This corresponds to a substrate processing system (FIG. 6C) having a chamber and a plurality of substrate processing apparatuses arranged so as to surround the transfer chamber.

  Further, in the embodiment described above, the substrate to be processed is a semiconductor wafer, but the substrate to be processed is not limited to this, and for example, a glass substrate such as an LCD (Liquid Crystal Display) or an FPD (Flat Panel Display). It may be.

  An object of the present invention is to supply a particle counter 41 or an external server, for example, an APC (Advance Process Control) server, to a storage medium that records software program codes for realizing the functions of the above-described embodiments. This can also be achieved by reading and executing the program code stored in the storage medium by the 41 particle detector 48 or the CPU of the APC server.

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

  As storage media for supplying the program code, RAM, NV-RAM, floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, MO, CD-R, CD-RW, DVD (DVD-ROM, DVD-RAM, DVD-RW, DVD + RW), magnetic tape, nonvolatile memory card, other ROM, or the like can be used. In addition, the program code may be downloaded via a network. In this case, the program code is supplied by downloading from another computer or database (not shown) connected to the Internet, a commercial network, or a local area network.

  Further, by executing the program code read out by the CPU, not only the functions of the above-described embodiments are realized, but also an OS (operating system) running on the CPU based on the instruction of the program code. 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 is also included.

 Further, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted into the particle counter 41 or the APC server or the function expansion unit connected to the particle counter 41 or the APC server, This includes a case where the CPU of the function expansion board or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing.

  The form of the program code may include an object code, a program code executed by an interpreter, script data supplied to the OS, and the like.

It is sectional drawing which shows schematic structure of the substrate processing apparatus with which the particle detection method which concerns on embodiment of this invention is applied. It is a figure which shows schematic structure of the particle monitor in FIG. It is a graph which shows the time change of the scattered light intensity | strength of the particle which passes the front of a light receiving sensor over several measurement periods. It is a flowchart of the particle detection method which concerns on this Embodiment. It is a graph which shows the time change of the scattered light intensity in case the scattered light resulting from two particles overlaps. FIG. 6A is a plan view illustrating a schematic configuration of a substrate processing apparatus having a substrate processing apparatus and a transfer chamber to which the particle detection method according to the present embodiment is applied, and FIG. 6A is a diagram illustrating a cluster type substrate processing system. FIG. 6B is a diagram showing a parallel type substrate processing system, and FIG. 6C is a diagram showing a substrate processing system having a double arm type transfer arm. It is a graph which shows the time change of the scattered light intensity to which the conventional detection method is applied.

Explanation of symbols

A Exhaust flow K Scattered light L0 to L10 Light flux P Particle R Exhaust flow passage area W Semiconductor wafer 2 Substrate processing apparatus 5 Gate valve 10 Chamber 11 Susceptor 12 Exhaust path 13 Baffle plate 14 APC
15 TMP
16 DP
18 High frequency power source 19 Matching device 20, 35 Electrode plate 22 DC power source 24 Focus ring 25, 81 Refrigerant chamber 26 Pipe 27 Heat transfer gas supply hole 28 Heat transfer gas supply line 29 Heat transfer gas supply unit 30 Pusher pin 31 Carry-in / out port 33 Shower Head 34 Gas vent 36 Electrode support 37 Buffer chamber 38 Process gas introduction pipe 39 MFC
40 Particle monitor 41 Particle counter 42 Laser light source 43 Projection optical system 44 Light receiving sensor 45 Detection optical system 46 Maximum scattered light intensity selection unit 47 Memory 48 Particle detection unit 49 Display unit

Claims (8)

A particle detection method for detecting particles carried by an air current,
A scattered light intensity measurement step of measuring the intensity of scattered light generated by scattering of light irradiated to the airflow by the particles at a predetermined timing by a light receiving means;
Maximum intensity measurement timing selection for dividing the measurement time for measuring the scattered light intensity into measurement periods every predetermined time and selecting the measurement timing at which the maximum scattered light intensity is measured among the measured scattered light intensity in each measurement period Steps,
A particle detection method comprising: a particle passage number counting step for counting the number of particles that have passed in front of the light receiving means based on the measurement timing selected in each measurement period.   In the particle passing number counting step, in each measurement period, when the selected measurement timing corresponds to either the start or end of each measurement period, the particles pass in front of the light receiving means. The particle detection method according to claim 1, wherein it is determined that the particle is not present.   The particle detection method according to claim 1, wherein the scattered light intensity measurement step does not measure the intensity of the scattered light smaller than a predetermined threshold.   The particle detection method according to claim 1, wherein the maximum intensity measurement timing selection step selects a maximum scattered light intensity together with the measurement timing.   5. The particle detection method according to claim 1, further comprising a particle particle size calculation step of calculating a particle size of the particles according to the maximum scattered light intensity.   6. The particle according to claim 1, wherein the scattered light intensity measuring step measures the intensity of scattered light of the light irradiated to the airflow in a processing chamber of the substrate processing apparatus. Detection method.   6. The scattered light intensity measuring step measures the intensity of scattered light of light irradiated on the airflow in an exhaust passage connected to a processing chamber of a substrate processing apparatus. The particle detection method according to any one of the above items. A particle detection program for causing a computer to execute a particle detection method for detecting particles carried by an air current,
A scattered light intensity measurement module that measures the intensity of scattered light generated by scattering of light applied to the airflow by the particles at a predetermined timing by a light receiving unit;
Maximum intensity measurement timing selection for dividing the measurement time for measuring the scattered light intensity into measurement periods every predetermined time and selecting the measurement timing at which the maximum scattered light intensity is measured among the measured scattered light intensity in each measurement period Module,
A particle detection program, comprising: a particle passage number counting module that counts the number of particles that have passed in front of the light receiving unit based on a measurement timing selected in each measurement period.

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