TW592889B - Protection device of preventing overpolish on a chemical mechanical polish machine and method thereof - Google Patents

Abstract

At least a current meter connecting to a CMP machine is provided to detect polishing signals from a polishing table. A controlling unit conditioned to a plurality of signal ranges and safe polishing times is provided to relate a signal range and a safe polishing time to each polishing signal. Furthermore, the controlling unit measures a lasting time of each polishing signal and gives an alarm while the lasting time of the polishing signal is greater than the safe polishing time, so as to prevent overpolish on the CMP machine.

Description

592889 V. Description of the Invention (l) Field of the Invention The present invention provides a protection device and method for avoiding overpolish of a chemical mechanical polish (CMP) machine, especially using a programmable logic A controller (programmable logic controller, PLC) reads the grinding signal provided by the chemical mechanical grinding machine itself, thereby avoiding excessive grinding. Background Description In the semiconductor process, CMP technology is currently the most commonly used, and at the same time, the most important planarization technology. CMP technology can be used to uniformly remove the topographical target thin film on a wafer, so that the wafer can have a regular and planar surface after CMP treatment. To ensure the depth of focus (DOF) in the subsequent yellow light process. In order to avoid over-wafering of the wafer or to control the thickness of the target thin film layer to be removed, the end point of the CMP must be accurately detected and quickly determined to stop the CMP process immediately. As CMP process involves many complicated process parameters at the same time, such as the characteristics of the target film layer, the uniformity of the surface of the target film layer, the composition of the slurry, the pH value, and the polishing

592889 V. Description of the invention (2) Composition of pads, table rotation speed, head down for ce of wafer carrier, etc. Decisions have always been a challenge for CMP technology. There are many known methods for determining the end point of CMP polishing. One of the simplest is to use the polishing time (by t i me) to control the polishing end point. However, the error produced by this method is often large, and the variation between different wafers is difficult to control, and the thin film layer to be polished needs to have a sufficient thickness to avoid excessive grinding. In addition, in order to avoid excessive lapping, a lapping stop layer (stop laye-r) is usually required under the target film layer. The removal rate of the grinding stop layer is usually smaller than the target film sound thereon. In other words, the rate at which the target grinding layer is to be ground is greater than the grinding stop layer below the target grinding ^. And other grinding end point detection methods, such as disclosed in US Patent No. 3,060,15, use the detection of the friction between different interfaces (fr 丨 ct 丨 0 n) to determine the grinding end point. It is disclosed in U.S. Patent No. 6 1 5 7 5 4 that the change in the measurement resistance (e 1 ecric resistance) is used to determine the polishing end point, and the currently most commonly accepted CMP process using optical principles to monitor the dielectric layer is to Decide on the end of grinding. When a photo detector is used to detect the financial CMP process, the detected reflected light intensity data will produce a periodic regular change, and then a periodic map is generated to detect the CMP. The end of the process.

592889 V. Description of the invention (3) And two = The above methods / methods can be used to detect the end of the CMP process. * Interference and human operation errors, etc., cause excessive wafer grinding, product scrap, and Machine pollution problems. Therefore, how to effectively grasp the wafer during the CMP process and over-research the grinding action of a ::: table to avoid the above problems has become an important issue for the production yield of k 幵. Summary of invention

The purpose of the present invention is to provide a protection device and method for effectively grasping the information of wafer over-grinding, which can avoid CMP machine from over-grinding and improve the yield of juice products. In a preferred embodiment of the present invention, the protection device includes at least one real-time meter electrically connected to a CMP machine for detecting a polishing signal of a polishing platform of the CMP machine, and a control unit, The control unit is provided with a plurality of signal ranges and a plurality of safe grinding times corresponding to each of the signal ranges, so as to determine the signal range and its location to which the grinding signal measured by the real-time measuring instrument belongs. Corresponding to the safe grinding time, at the same time, the control unit measures the relationship between the grinding signal and the operating time of the CMP machine so that the operating time of the grinding signal within the signal range to which it belongs belongs to the safe grinding of the signal range A warning message is issued at time to avoid the excessive grinding phenomenon.

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Since the present invention can detect conventional CMP traps in Litian # 兹 故 #, using traditional methods and equipment, it is additionally provided—an effective device and method for screening wafer excessive grinding information, so it can effectively avoid黧 The machine itself 黧 ra: The problem that the CMP machine cannot be stopped caused by "efficiency, mechanical movement irregularity, noise interference and human operation error", which can avoid excessive grinding of the CMP machine port and improve product yield. Details of the invention Description

㉔Refer to Fig. 1 'Fig. 1 is a schematic diagram of a CMP machine used in the present invention. The CM P machine 10 includes a polishing platform 12, a polishing pad η is disposed on the polishing platform 12, a wafer carrier 16 is disposed above the polishing pad 14, and is used to carry a wafer 18 to be polished, and A polishing liquid supply device 20 is configured to supply a polishing liquid to the polishing pad 14 to remove a substance to be polished on the wafer 18. In addition, the CMP machine 10 further includes a drive motor 2 2 and a drive motor 24 respectively electrically connected to a computer control system 32 to control the CMP machine 10 according to the CMP operating parameters set by the computer control system 32. Grinding operation, in which the drive motor 2 2 series is electrically connected to the wafer carrier 16 to control the pressure and speed under the wafer carrier 16, and the drive motor 2 4 series is electrically connected to the polishing platform 12 2 for control Rotation speed of grinding platform 12 In order to avoid the situation that the wafer 18 is over-polished during the CMP process, the present invention further sets a protection device on the CMP machine 10, including an instant meter 28, which is electrically connected to the drive motor 22, Used to detect the drive

592889 V. Description of the invention (5) Grinding signal and various load data of the motor 22, an instantaneous meter 26 which is electrically connected to the driving motor 24, for detecting the grinding signal and various loads of the driving motor 22 Data, and a control unit 30, such as a programmable logic controller, for receiving various grinding signals detected by the real-time meters 26, 28, and analyzing and processing the above-mentioned various grinding signals . Please refer to FIG. 2. FIG. 2 is a flowchart 40 of a method for determining and analyzing a grinding signal by the control unit 30 of the present invention. For the convenience of explanation, the flow chart 40 is used to analyze the grinding information measured by the real-time meter 2 6 from the grinding platform 12

For example, the grinding signal detected by the real-time meter 2 8 can also be analyzed according to the method and steps shown in the flowchart 40. As shown in FIG. 2, in the method of the present invention, the control unit 30 first reads the grinding signal detected from the grinding platform 12. As shown in step 41, the grinding signal received by the control unit 30 includes: A machine grinding on / off signal (digital signal) Si is used to display the on / off state of the CMP machine 10 for grinding.

The signal (analog signal) s 2 is converted at the speed of the grinding platform, and it is used to provide the following analysis data when the flat port 1 2 is opened. Where machine = :, the on / off signal s can also be directly output by the computer control system 32 to the second product = 0 'grinding platform speed conversion signal S 2 can be a voltage signal; =; used to reflect wafer 18's poem polishing & Status value; z, 1〇 Rotational speed of grinding platform 1 2 is determined. In addition, CMP

Ui is used as parameters, including wafer carrier down pressure, wafer carrier may affect i 2 Ϊ: change of parameters such as polishing pad type or polishing installation type, which is the value of the polishing platform speed conversion signal s. Worth mentioning

Page 10 592889 V. Description of the invention

It is 'with the adjustment of the rotation speed of the grinding platform 12' Among the various grinding signals provided by the CMP machine, the voltage signal can provide a more sensitive analog signal I, so it is recommended that this voltage signal can be used as a speed conversion of the grinding platform. The signal Sr is used to control the age of the CMP machine 10 whether excessive grinding occurs. 1 As shown in step 42, after reading the grinding platform speed conversion signal s, the control unit 30 next determines the grinding signal range R of the grinding platform speed conversion signal S and the safe grinding time T according to the settings of the internal database. i. At the same time, the control unit 30 also reads the duration ti of the polishing platform speed conversion signal S within the polishing signal range R, as shown in step 43. After that, the control unit 30 compares the polishing duration time seven with the safe polishing time T within the same polishing signal range R. When the polishing time t i < the safe polishing time T spans, it means that the wafer 18 is at In the standard CMP manufacturing process, the condition of over-grinding does not occur, so the operation flow of the control unit 30 will jump from step 4 3 to step 41, and continue to read and monitor the grinding signals s private and s. When the polishing time t > the safe polishing time τ, it means that the polishing duration ti in the polishing signal range R i of 2 wafers 18 at this stage has exceeded the safe polishing time T i set by the system, so the control unit 3 at this time 〇 Proceed to step 4 4 to issue a warning message to remind the system or operator to take security measures. The warning message can be any type of information such as sound or image. After receiving the warning message, the system or operator can use the manual or automatic mode to adjust the operating parameters of the CMP machine and appropriately adjust the supply of polishing liquid. Supply of device 20, or adjustment of wafer carrier

592889

V. Description of the invention (7) Force to achieve the effect of real-time compensation of the curved surface, or directly stop the CMP machine 10 from grinding the wafer 18 to effectively avoid excessive grinding.

In order to clarify the method flow shown in FIG. 2, the relationship between the polishing signal value of the polishing signal s r S 2 and the polishing time t is shown in FIG. 3. As shown in Figure 3, the horizontal axis represents the grinding time, and the vertical axis represents the magnitude of the grinding signal. In the preferred embodiment of the present invention, the machine grinding on / off signal S and the grinding platform speed conversion signal s are displayed in a common window. Among them, the grinding on / off signal s of the machine is a digital signal, the value of which only changes between 0 and 1, which are used to show the grinding platform i 2 series f is closed or on. When the value of the grinding signal S 夂 is 1, that is, when the Xin grinding platform 12 is turned on and starts to rotate, the value of the grinding signal sa will also be presented according to the operating parameter adjustment of the system setting (such as the rotation speed adjustment of the grinding platform 12). change. Taking a CMP process to planarize the tungsten metal layer in the tungsten plug as an example, it is assumed that the internal database of the control unit 30 is set with two grinding signals (voltage signals) ranging R and R2, where R i is Between the grinding signal values V 1 and V 夂, R between the grinding signal values V and V 夂, Vr V and Vf are set to 0 · 3 volts, 1.8 volts, and 5 volts, respectively, and the control unit 3 0 The safe grinding times set in the grinding signal ranges R and r are respectively T and T 2, and T and T are 70 seconds each. When the grinding platform 12 is placed in the open state, the 'control unit 30' will first measure the grinding duration t! Of the grinding platform speed conversion signal S within the grinding signal range R, and then compare t with the grinding signal range The safe grinding time T i set by R, when t < T i

Page 12 592889 V. Description of the invention (8), the control unit 30 will continue to measure the grinding duration 112 of the honing platform speed conversion signal S within the grinding signal range R, otherwise a warning message will be issued to avoid CMP The machine 10 was excessively ground. Similarly, in the second stage, after measuring the grinding time t, the control unit 30 will also compare the safe grinding time τ 2 set by t with the grinding signal range R. When t2 < τ is held, the control unit 30 will Continue to measure the grinding time for real-time monitoring, otherwise an alarm sfL message will be issued. In addition, in order to improve the reliability of the monitoring method of the present invention, the control unit 30 can set a safe grinding time of about 160 seconds in addition to the safe grinding time T 1 and T set according to the grinding signal ranges R and R 捋. Time T 3, or set T 3 = T JT 2+ 10 seconds. Through the safe grinding time T image setting, even if the control unit 30 fails to monitor the grinding time t and t in the first and second stages, the grinding time 13 (the grinding signal range is between Between V and V, and 13 = t12 + 10 seconds) compared with the safe grinding time T step, hold tp T to force the CMP machine 10 to adjust the grinding operation parameters or stop the grinding action to effectively avoid excessive grinding.

Since the present invention uses the real-time meter 26 to capture the real-time grinding signal-Sp S2 of the CMP machine 10, and the control unit 30 sets the safe grinding time for each stage of the CMP process, so when the control unit 30 reads When the polishing platform speed conversion signal S is reached and the grinding time reaches or exceeds the safe grinding time set by the system, a warning message will be issued to remind the system or the operator to take safety measures to avoid losses caused by excessive wafer grinding. And the present invention

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The monitoring method for the grinding signal can also be applied to other semiconductor manufacturing process equipment, such as the application of deposition equipment such as oxide or metal layers. The control unit sets the safe deposition time to be provided by the equipment itself. The accumulated time of the deposition signal is compared to achieve the real-time monitoring effect to avoid problems related to product scrap caused by repeated deposition. Compared with the conventional technology, the present invention can use traditional methods and devices to detect the end of the CMP process, and provide a protective device and method for effectively screening wafer pass " degree polishing information, so it can effectively avoid The CMP machine's own light detection efficiency, mechanical motion irregularity, noise interference, and human operation errors cause the CMP machine cannot stop, which can "in order to avoid excessive grinding of the CMP machine and improve product yield. The above are only the preferred embodiments of the present invention, and any equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the patent of the present invention. / Φ

592889 Simple illustration of the diagram Simple illustration of the diagram Figure 1 is a schematic diagram of the CMP machine used in the present invention. Fig. 2 is a flowchart of a method for judging a grinding signal by a control unit of the present invention. Fig. 3 is a relationship diagram between a grinding signal and a grinding time of the present invention. Symbols shown in the figure 10 12 14 16 18 20 22 26 30 32 40 41 S 1 S 2 Ri, T, 24 28 42 ^ 43 ^ 44 R2 CMP machine polishing platform polishing pad wafer carrier wafer polishing liquid supply device driver Motor real-time meter control unit computer control system method flowchart analysis steps ^ Machine grinding on / off signal grinding platform speed conversion signal grinding signal range safe grinding time

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Page 16

Claims (1)

592889 VI. Scope of patent application 1. A protection device to avoid excessive polishing of a chemical mechanical polish (CMP) machine 'The chemical mechanical polishing machine includes a polishing table, The protection device includes: at least one current meter electrically connected to the grinding platform for detecting a voltage signal of the grinding platform; and a control unit electrically connected to the real-time meter, The voltage signal measured by the real-time meter is monitored according to a preset procedure to avoid the phenomenon of excessive grinding of the wafer. 2 _ For the protection device under the scope of patent application, the voltage signal includes a digital signal to display the on / off status of the grinding platform. 3 · As for the protection device in the scope of patent application, the voltage signal includes an analog signal for performing the preset procedure when the grinding platform is turned on. 4 · If the protection device of the scope of the application for the patent, the chemical mechanical polishing machine further includes a polishing pad on the polishing platform, a carrier head is arranged above the polishing pad 'It is used to carry a wafer to be polished and a slurry slurry supply device for supplying a polishing liquid to the polishing pad. Page 17 592889 6. Scope of patent application 5. The protection device according to item 1 of the scope of patent application, where the voltage signal 丨 is determined by the operating parameters of the CMP machine. • Enter the protection device of item 5 in the scope of the patent application, where the operating parameters include the head down force of the Japanese yen carrier, the head rotation speed of the wafer carrier, and the table rotation speed (table r〇tati). n speed), pa (j type) or siurry type. ^ For the protection device under the scope of the patent application, the preset process includes the following steps: 丨 :: Ξ ί: S voltage ΞI and a plurality of voltage signals f corresponding to each of the voltage ranges in the voltage f to which the voltage signal belongs • When the voltage signal belongs to the | alarm _: ... grinding time, the control unit will … Contains the sound ': 2 = the protective device surrounding item 7', the warning message The table will follow the instructions; the smashing of the chemical mechanical grinding machine grinding machine: "hand == movement mode to adjust the chemical machine to stay in the parameters" to avoid the excessive grinding phenomenon. Page 18, 592889 VI. Application for Patent Scope 9 · If the protection device for scope 7 of the patent application is applied, the warning message contains any type of information such as sound or image, and the chemical mechanical grinding machine will use the warning message according to the warning message. Manual or automatic mode to prevent the wafer from continuing to be polished under the voltage signal, so as to avoid the excessive grinding phenomenon. 1 0 · If the protection device of the scope of patent application No. 1 wherein the control unit is a programmable logic controller (pr0grammabie l0gic controller, PLC) ° 11. · A method for avoiding excessive grinding in a chemical mechanical polishing process' The method includes: >, at least one instant meter electrically connected to a chemical mechanical polishing (CMp) machine for detecting One of the grinding signals of one of the grinding platforms of the chemical-mechanical grinding machine; and, I 仏 a control unit; the control unit is provided with a plurality of signal ranges; and, a plurality of safe grinding time corresponding to each of the signal ranges, , 2 ί t Ϊ I 卩, the measuring device measures the grinding signal to which the I 1 belongs, and the corresponding safe grinding time, and measures the research signal and the CMP machine as the questionnaire M ^ ^ Research ^ 关系 The relationship between the time of naked cropping, so that the grinding signal in the range of the signal belongs to the female signal αλ „^ ^ solid operation time is longer than the signal grinding time of the security grinding time is issued here-outside * ^ ^ No warning message to avoid the phenomenon of excessive grinding 1 2 · As in the method of item 11 of Zhong 4 Patent Fan® 1, where the grinding signal contains Page 19 592889 VI. Scope of patent application A digital signal used to display the on / off status of the grinding platform. 1 3. The method according to item 11 of the patent application range, wherein the grinding signal includes an analog signal for providing the control unit to determine the signal range to which the control unit belongs when the grinding platform is placed in an open state. 14. The method according to item 11 of the patent application range, wherein the polishing signal is a voltage signal or a wafer surface temperature signal. 1 5. The method according to item 11 of the scope of patent application, wherein the polishing signal is determined by the operating parameters of the CMP machine. 16. The method according to item 15 of the scope of patent application, wherein the operating parameters include wafer carrier down pressure, wafer carrier rotation speed, platform rotation speed, grinding mill type or grinding slurry type. 17. The method according to item 11 of the scope of patent application, wherein the control unit is a programmable logic controller. ❿ 1 8. The method according to item 11 of the scope of patent application, wherein the warning message includes any type of information such as sound or image, and the chemical mechanical grinding machine will adjust the manual or automatic mode according to the warning message. Operating parameters of the CMP machine to avoid this excessive grinding phenomenon. Page 20 592889 VI. Application for Patent Scope 1 9. If the method for the scope of patent application No. 11 is adopted, the warning message includes any type of information such as sound or video, and the chemical mechanical grinding machine will use the warning message according to the warning message. Manual or automatic mode to prevent the wafer from continuing to be polished under the polishing signal to avoid the excessive polishing phenomenon. Page 21 ·