WO2008088164A1

WO2008088164A1 - The wireless monitor system for the precision monitoring of the processing machine having the rotational structure

Info

Publication number: WO2008088164A1
Application number: PCT/KR2008/000256
Authority: WO
Inventors: Jung Hwan An; Myung Soo Kim; Sung Ryul Kim
Original assignee: University Industry Cooperation Foundation of Pusan National University
Current assignee: University Industry Cooperation Foundation of Pusan National University
Priority date: 2007-01-19
Filing date: 2008-01-15
Publication date: 2008-07-24
Anticipated expiration: 2009-07-19
Also published as: KR100845283B1

Abstract

Disclosed herein a wireless monitoring system for precisely monitoring the processing status of a processing machine having a rotating structure. The system includes an Acoustic Emission (AE) sensor unit for detecting AE signals generated when material is changed, a signal amplification unit for amplifying the minute signals, a signal processing unit for filtering the amplified signals and converting the analog signals into digital signals, an interface unit for wirelessly transmitting and receiving the signals, a microcomputer for detecting the status of the processing machine by analyzing, performing a diagnosis on and monitoring the signals, and the controller of the processing machine for receiving command signals and controlling the processing machine, wherein the signal processing unit is a Digital Signal Processing (DSP) unit that contains a digital signal processor, converts the analog signals into digital signals, performs high-speed filtering on the signals, and transmits the signals to the interface unit.

Description

THE WIRELESS MONITOR SYSTEM FOR THE PRECISION

MONITORING OF THE PROCESSING MACHINE HAVING

THE ROTATIONAL STRUCTURE

Technical Field

[1] The present invention relates, in general, to a wireless monitoring system for precisely monitoring a processing machine having a rotating structure and, more particularly, to a wireless monitoring system for detecting an Acoustic Emission (AE) signal from a processing machine having a rotating structure, such as a Chemical- Mechanical Polishing (CMP) machine, a lapping machine or a grinding machine, wirelessly sending the detected signal to a location away from the processing machine, wirelessly receiving the signal, and analyzing, performing diagnosis on and monitoring the received signal. Background Art

[2] With regard to various types of processing machines, there are cases in which, in order to perform operation control, it is necessary to detect changes in various states of the processing machines and send detected signals to desired locations.

[3] In greater detail, it is well known that, for example, in processing machines having rotating structures, AE signals, which are ultrasonic waves, are generated in a CMP process. Accordingly, it is possible to detect an AE signal generated due to contact and determine the state of the contact between polishing particles and a wafer based on the level of the signal. As a result, various devices for detecting and sending AE signals have been proposed.

[4] For example, as shown in Fig. 1, Korean Patent No. 10-0596379 discloses a CMP endpoint detection system, which shows a technology for, in a CMP process, detecting an AE signal, that is, elastic energy which is generated when solid material is subjected to plastic deformation or broken and is transmitted through a solid body in the form of sound waves, using an AE sensor and transmitting the detected signal using a Bluetooth wireless transmission method.

[5] In the above-described method, an AE sensor 1 for detecting AE signals uses the following relational expression:

[6] MathFigure 1

[7] wherein represents an original AE signal and is an average time based on a Root Mean Square (RMS) value.

[8] From the above Equation 1, it can be seen that the AE sensor 1, attached onto a carrier head 13, measures an AE signal in such a way as to measure an ultrasonic frequency generated by the interaction between polishing particles and a wafer 14 based on the ultrasonic Doppler principle and calculate the average magnitude of the AE signal using an RMS value.

[9] Furthermore, as shown in fig. 2, the conventional CMP endpoint detection system is configured to include an AE signal processing unit 2. The AE signal processing unit 2 is formed of various components, including an amplifier 23, a bandpass filter 24, an RMS converter 25 and a microcomputer 26, so that the size of a board is increased, and thus the installation of the conventional CMP endpoint detection system is limited to specific places, with the result that the free use of the conventional CMP endpoint detection system is restricted. Accordingly, the conventional CMP endpoint detection system has a problem in that it cannot be applied to apparatuses that must have a small size.

[10] Furthermore, the accuracy of a conventional analog signal processing method or a separate digital circuit method for processing signals depends greatly on the intensity of an AE signal that is scattered and reflected, and the calculation of an RMS value depends on an analog-type low-pass filtering method of converting a high-frequency Alternating Current (AC) signal into a low-frequency Direct Current (DC) signal using a bandpass filter 24. Accordingly, many errors may occur in practice.

[11] Accordingly, the processes of performing low-pass filtering on the AE signal using the bandpass filter 24, inputting the filtered AE signal to the RMS converter 25, performing full-wave rectification on the signal and then outputting the AE signal as a RMS value have the following problems. When the conventional analog circuit method, such as that shown in Fig. 2, or a conventional method of processing ultrasonic signals using only digital logic circuits, such as individual digital circuits or a gate array, is employed, measurement can be performed only within a limited range, and the possibility of errors is high because original signals may be easily distorted by disturbance due to surrounding noise from the point of view of the circuit characteristics of analog parts (a filter and an RMS-DC converter), rather than an amplifier. Even when a method of processing signals using a conventional microprocessor is employed, it is impossible to process all signals from the AE sensor in real time because the speed of the processing of signals is low, and an AE signal is calculated using an arithmetic average within a restricted range. Disclosure of Invention Technical Problem [12] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to enable a processing machine having a rotating structure to be precisely monitored by handling signal processing and operation through a digital filtering operation and a Fast Fourier Transform (FFT) operation using a digital algorithm, which performs processing at a speed of 150 MHz, based on a digital signal processor.

[13] Furthermore, another object of the present invention is to provide a wireless monitoring system for precisely monitoring a processing machine having a rotating structure that is capable of obtaining accurate and trustworthy measured signals while meeting the demand for a small size.

[14] Furthermore, a further object of the present invention is to enable various additional functions to be implemented using a microcomputer on which an embedded Linux is installed so that AE signals can be measured even in complicated situations, data measured for a specific period or longer can be stored, data can be transmitted to the controller of the processing machine in a digital manner, and the monitoring of the status of the processing machine can be facilitated, in response to the demand for functions of transmitting digital data to a remote location in real time during the measurement of AE signals from the processing machine having a rotating structure, and collecting and storing data measured for a specific period or longer when a communication line is disconnected. Technical Solution

[15] In order to accomplish the above object s, the present invention provides a wireless monitoring system for precisely monitoring a processing status of a processing machine having a rotating structure, the system including an Acoustic Emission (AE) sensor unit for detecting AE signals generated when material is changed, a signal amplification unit for amplifying the minute signals detected by the AE sensor unit, a signal processing unit for filtering the amplified signals and converting the analog signals into digital signals, an interface unit for wirelessly transmitting and receiving the signals output from the signal processing unit, a microcomputer for detecting the status of the processing machine by analyzing, performing a diagnosis on and monitoring the signals transmitted from the interface unit, and the controller of the processing machine for receiving command signals from the microcomputer and controlling the processing machine, wherein the signal processing unit is a Digital Signal Processing (DSP) unit that contains a digital signal processor, converts the analog signals, amplified by the signal amplification unit, into digital signals, performs high-speed filtering on the signals, and transmits the signals to the interface unit.

[16] Preferably, the interface unit is equipped with an integrated interface system, including Ethernet, Bluetooth and RS-232C/422/485, thereby enabling Internet access via Ethernet and local area wireless access via Bluetooth. [17] Preferably, the interface unit further includes a Universal Serial Bus (USB) memory unit that is capable of constructing a database and storing and managing the measured data using the database. [18] Preferably, the microcomputer is operated using a dual Operating System (OS) in such a way that a Soft Real-time System is implemented using an embedded Linux system, including a Linux kernel, and a hard real-time system is implemented on the

DSP unit. [19] Preferably, the microcomputer further includes a Thin Film Transistor (TFT) Liquid

Crystal Display (LCD) unit in which a TFT LCD is employed and a touch screen and a

Graphic User Interface (GUI) system are implemented. [20] Preferably, the monitoring system further includes a DC-DC converter unit that converts power, supplied through contact between a fixed brush connected to an external power source unit and a slip ring attached onto the rotating structure, into DC power having different voltages necessary for operation of the DSP unit and the interface unit, and stabilizes and supplies the resulting DC power.

Advantageous Effects

[21] The above-described present invention has advantages in that measured signals from the AE sensor, which is configured to measure the status of the processing machine, store measured data in the processing machine itself for a long time and transmit data to a remote location, are directly processed using a high-speed digital algorithm in the digital signal processor, operating at 32 bit, 150 MHz speed, so that noise components are effectively removed from frequencies when AE signals are measured from the processing machine and then the signal data from the AE sensor unit is processed using a statistical method. Meanwhile, the signal data based on the status of a processing machine is processed using an FFT operation and a high-speed digital filtering operation, and then the AE signals based on the state of the processing machine can be stably and securely transmitted from the AE sensor unit.

[22] Furthermore, the present invention has significant advantages in that it is possible to efficiently manage data about the status of processing machine in a typical microcomputer because a database is constructed and used in USB memory, and in that data, obtained by measuring and storing the status of the processing machine, can be downloaded and the status data can be checked and examined over the Internet because the system can be directly connected to the controller of the processing machine via Ethernet or Bluetooth. Brief Description of the Drawings [23] Fig. 1 is a schematic diagram showing the entire system of a CMP machine having a conventional CMP endpoint detection system;

[24] Fig. 2 is a diagram showing the construction of the conventional CMP endpoint detection system;

[25] Fig. 3 is a schematic diagram showing a wireless monitoring system for precisely monitoring a processing machine having a rotating structure according to a preferred embodiment of the present invention; and

[26] Fig. 4 is a diagram showing the construction of the wireless monitoring system for precisely monitoring a processing machine having a rotating structure according to the preferred embodiment of the present invention.

[27] *Description of reference numerals of principal elements in the drawings*

[28] 10: AE sensor unit 20: signal amplification unit

[29] 22: charge amplifier 24: voltage amplifier

[30] 30: DSP unit 40: interface unit

[31] 42: USB memory unit 50: microcomputer

[32] 52: TFT LCD display unit 60: controller of processing machine

[33] 70: DC-DC converter unit

Best Mode for Carrying Out the Invention

[34] Hereinafter, embodiments of the present invention will be described in greater detail with reference to the attached drawings.

[35] Fig. 3 is a schematic diagram showing a wireless monitoring system for precisely monitoring a processing machine having a rotating structure according to a preferred embodiment of the present invention, and Fig. 4 is a diagram showing the construction of the wireless monitoring system for precisely monitoring a processing machine having a rotating structure according to the preferred embodiment of the present invention.

[36] Since the processing machine having a rotating structure has a well-known construction, a detailed description thereof will be omitted here.

[37] As shown in Figs. 3 and 4, the wireless monitoring system for precisely monitoring the processing status of a processing machine according to the present invention includes an AE sensor unit 10, a signal amplification unit 20, a Digital Signal Processing (DSP) unit 30, an interface unit 40, a microcomputer 50, and the controller 60 of a processing machine.

[38] In the above description, the AE sensor unit 10 is a sensing unit that is attached onto a carrier head 13 and is used to detect AE signals generated by the interaction between polishing particles and a wafer 14. Such an 'AE signal' in the AE sensor unit 10 refers to elastic energy that is generated when solid material is subjected to plastic de- formation or broken and is then transmitted through a solid body in the form of waves. With regard to this AE signal, the frequency and magnitude of a generated AE signal vary with the amount of processing load and the characteristics of material. Generally, it is known that, when the amount of processing load increases with the hardness of material and the type of polishing particles, an AE signal also increases.

[39] A minute AE signal, detected by the AE sensor unit 10, is transmitted to the signal amplification unit 20 through a signal cable.

[40] Next, the signal amplification unit 20 includes a charge amplifier 22 for converting an input high-impedance signal, input from the AE sensor unit 10, into a low- impedance signal, and a voltage amplifier 24 for amplifying the voltage of a signal output from the charge amplifier 22.

[41] The signal, amplified by the signal amplification unit 20 as described above, is transferred to the DSP unit 30.

[42] Next, the DSP unit 30 contains a digital signal processor chip. The DSP unit 30 converts the analog signal, amplified by the signal amplification unit 20, into a digital signal, receives the resultant digital signal, calculates a value using an ultra-high speed digital algorithm in real time, and performs conversion into a signal to be input to the input terminal of the interface unit 40.

[43] Accordingly, the DSP unit 30 is desirable in that it occupies a very small area in the processing machine having a rotating structure.

[44] Furthermore, the DSP unit 30 performs filtering for removing unnecessary noise and interference, and transfers a highly sensitive output signal to the microcomputer 50 through the interface unit 40.

[45] The interface unit 40 is configured to transmit measured data using a serial port, such as an RS-232C/422/485, Ethernet or Bluetooth, and check the status of the processing machine. In particular, the interface unit 40 may use Ethernet or Bluetooth to wirelessly transmit measured data in real time. The interface unit 40 is not attached onto a polishing head, but is installed at a specific location in a main body.

[46] In the embodiment of the present invention, it is preferred that the interface unit 40 transmit a sensing signal to the external microcomputer 50 using a Bluetooth communication method. Bluetooth is a microcomputer and communication industry standard that defines the efficient connection between telephones and microcomputers in homes and companies that use local area wireless access for mobile phones, microcomputers and Personal Digital Assistants (PDAs). Each device is equipped with a microchip transceiver capable of performing transmission and reception in the 2.4 GHz band, which is a frequency band that is available worldwide. A maximum of three voice channels may be used, in addition to a data channel. The maximum communication range is 100 m, and data is transmitted at a speed of about 1 Mbps. [47] As described above, the interface unit 40 receives a signal transmitted using a

Bluetooth communication method, and transmits the signal to the microcomputer 50 through a serial port or Ethernet. In the case of high-speed signal transmission, the interface unit 40 may temporarily store data using a USB memory unit 42 as a buffer, and then transmit a signal to the microcomputer.

[48] Meanwhile, according to another preferred embodiment of the present invention, it is preferred that the interface unit 40 include the USB memory unit 42. The USB memory unit 42 is configured such that high-capacity removable USB memory can be directly connected and then used. This USB memory is configured such that data, collected for 1 year or longer, is organized into a database based on date using a systematic file system, so that the measured data can be efficiently processed and easily managed and utilized, with the result that the microcomputer 50 can easily utilize the measured data.

[49] Next, the microcomputer 50 detects the status of the processing machine by analyzing, performing diagnosis on and monitoring a signal transmitted from the interface unit 40, and transmits a command signal to the controller 60 of the processing machine based on information from the analysis, so that the controller 60 of the processing machine controls the processing machine. The microcomputer 50 is equipped with a 32-bit ARM embedded processor, 64-MByte flash ROM and SDRAM, is connected to a TFT LCD unit 52 using a 6.4" TFT LCD and then performs display using a Graphic User Interface (GUI), and is equipped with a serial port (such as RS-232C/422/485) and Ethernet and Bluetooth communication interfaces and then facilitates the transmission of measured data. Meanwhile, the microcomputer 50 is provided with an embedded Linux using a 2.6.x kernel, stores measured raw data, measurement result data and measured dates and times together, transmits data to the controller 60 of the processing machine, and enables the overall setting of the processing machine and measured data through the TFT LCD display unit 52 to be monitored, managed and set, and the transmission of measured data and the checking and setting of the status of the processing machine to be freely performed using Ethernet, Bluetooth or a serial port.

[50] As described above, the microcomputer 50 transmits a command to the controller

60 of the processing machine based on analysis information, thereby being able to control the operation of the processing machine.

[51] Meanwhile, power supplied to the DSP unit 30 and the interface unit 40 is supplied through a DC-DC converter unit 70.

[52] The DC-DC converter unit 70 converts DC power having a voltage, supplied through contact between a fixed brush 6, connected to an external power source unit 7, and a rotating slip ring 5, into DC power having voltages necessary for operation, stabilizes the power, and supplies respective parts of the power to the DSP unit 30 and the interface unit 40. The DC-DC converter unit 70 is a device for converting DC power having an input voltage (for example, +15V) into DC power having different voltages (for example, +15V, -15V, and +5V) and stabilizes it, and is widely used to convert single input power into a plurality of output voltages. This power supply method using the slip ring 5 is more effective in the case in which power must be continuously supplied.

[53] Next, the operation of the wireless monitoring system for precisely monitoring a processing machine having a rotating structure according to the present invention will be described with reference to the accompanying drawings.

[54] When the polishing particles of the processing machine having a rotating structure come into contact with the wafer and then polishing is performed, an AE signal is generated and is detected by the AE sensor unit 10. At this time, the level of the generated AE signal is determined by the interaction between the polishing particles and the wafer, and the frequency and magnitude of the generated AE signal vary with the amount of processing load and the characteristics of the material.

[55] The signal, detected by the AE sensor unit 10, is amplified by the signal amplification unit 20, subjected to high-speed filtering performed by the digital signal processor of the DSP unit 30, converted into a digital input signal to be input to the input terminal of the interface unit 40, and transmitted to the interface unit 40.

[56] The signal, transmitted from the interface unit 40, is received by the microcomputer

50 of the processing machine, so that a command signal for operation control, such as analysis, diagnosis or monitoring, is received from the controller 60 of the processing machine and processing is performed.

[57] Furthermore, the DC-DC converter unit 70 converts DC power having an input voltage into DC power having different voltages necessary for operation, stabilizes the resulting power, and supplies the resulting power to the DSP unit 30 and the interface unit 40.

[58] As described above, in the above-described construction, AE signals, generated by contact between the polishing particles and the wafer and polishing, are processed by the digital signal processor of the DSP unit 30. Accordingly, the AE signals are processed directly by a high-speed digital algorithm, so that noise components are effectively removed from frequency at the time of measuring the AE signals of the processing machine, and then the signal data from the AE sensor unit 10 is processed using a statistical method. Meanwhile, the signal data based on the status of the processing machine is processed through an FFT operation and a high-speed digital filtering operation, and then the AE signals based on the status of the processing machine can be stably and securely transmitted from the AE sensor unit 10. [59] Although a description has been given with a focus on the specific embodiment of the present invention, it is obvious that the above-described various modifications and variations can be made within a range that does not depart from the technical spirit set forth in the claims of the present invention. Accordingly, the detailed description of the present invention and the accompanying drawings should not be interpreted as limiting the technical spirit of the present invention, but should be interpreted as being illustrative.

Claims

[1] A wireless monitoring system for precisely monitoring a processing status of a processing machine having a rotating structure, the system comprising an Acoustic Emission (AE) sensor unit for detecting AE signals generated when material is changed, a signal amplification unit for amplifying the minute signals detected by the AE sensor unit, a signal processing unit for filtering the amplified signals and converting the analog signals into digital signals, an interface unit for wirelessly transmitting and receiving the signals output from the signal processing unit, a microcomputer for detecting a status of the processing machine by analyzing, performing a diagnosis on and monitoring the signals transmitted from the interface unit, and a controller of the processing machine for receiving command signals from the microcomputer and controlling the processing machine, wherein the signal processing unit is a Digital Signal Processing (DSP) unit that contains a digital signal processor, converts the analog signals, amplified by the signal amplification unit, into digital signals, performs high-speed filtering on the signals, and transmits the signals to the interface unit.

[2] The wireless monitoring system as set forth in claim 1, wherein the interface unit is equipped with an integrated interface system, including Ethernet, Bluetooth and RS-232C/422/485, thereby enabling Internet access via Ethernet and local area wireless access via Bluetooth.

[3] The wireless monitoring system as set forth in claim 2, wherein the interface unit further comprises a Universal Serial Bus (USB) memory unit that is capable of constructing a database and storing and managing the measured data using the database.

[4] The wireless monitoring system as set forth in claim 1, wherein the microcomputer is operated using a dual Operating System (OS) in such a way that a Soft Real-time System is implemented using an embedded Linux system, including a Linux kernel, and a hard real-time system is implemented on the DSP unit.

[5] The wireless monitoring system as set forth in claim 4, wherein the microcomputer further comprises a Thin Film Transistor (TFT) Liquid Crystal Display (LCD) unit in which a TFT LCD is employed and a touch screen and a Graphic User Interface (GUI) system are implemented.

[6] The wireless monitoring system as set forth in claim 1, further comprising a

Direct Current (DC)-DC converter unit that converts power, supplied through contact between a fixed brush connected to an external power source unit and a slip ring attached onto the rotating structure, into DC power having different vol tages necessary for operation of the DSP unit and the interface unit, and stabilizes and supplies the resulting DC power.