A retainer for online detection of polishing liquid state and a detection method

Abstract

The application discloses a kind of online detection polishing liquid state's retainer and detection method, belong to wafer polishing technical field.Online detection polishing liquid state's retainer, including retainer body, the lower portion of retainer body is provided with polishing pad, polishing pad is fixed on rotary table, the upper portion of polishing pad is provided with polishing liquid tank, retainer body is connected with connecting seat by fixed seat, controller is set on connecting seat, connecting seat is connected with external power component, power component, polishing liquid tank and rotary table are electrically connected with controller;The bottom of retainer body is provided with several liquid inlet holes for making polishing liquid enter the inside of retainer, the inside of retainer body is provided with several ultrasonic detection components for detecting the polishing liquid that enters the inside of retainer by liquid inlet hole.Adopt the online detection polishing liquid state's retainer and detection method of the application, can solve the problem that existing wafer polishing equipment cannot carry out real-time detection to polishing liquid, influence wafer polishing effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer polishing, in particular to a guard ring for on-line detection of polishing liquid state and a detection method. BACKGROUND

[0002] In the wafer manufacturing process, the polishing process is a crucial link, which directly affects the performance and quality of the wafer. The polishing liquid is a key consumable in the polishing process. The existing wafer polishing equipment drives the wafer to move on the polishing pad through the guard ring, sets a polishing liquid tank above the polishing pad, sprays the polishing liquid onto the polishing pad through the polishing liquid tank, and polishes the surface of the wafer through the polishing liquid while the wafer is moving on the polishing pad driven by the guard ring. With the continuous development of semiconductor manufacturing technology, the precision and stability of the polishing process are required higher and higher, and the stability of the concentration, particle distribution and liquid level of the polishing liquid plays a decisive role in the polishing effect. The concentration, particle distribution and liquid level of the polishing liquid are generally obtained by pre-prepared polishing liquid and controlled flow of the polishing liquid, but in the long-term polishing process, the concentration, particle size distribution of the polishing liquid and the stability of the liquid level will fluctuate to a certain extent, and the fluctuation of the parameters will cause scratches and other defects on the surface of the wafer, affecting the polishing effect and yield of the wafer. SUMMARY

[0003] The purpose of the present application is to provide a guard ring for on-line detection of polishing liquid state and a detection method, which solves the problem that the existing wafer polishing equipment cannot detect the polishing liquid in real time, affecting the polishing effect of the wafer.

[0004] To achieve the above-mentioned purpose, the present application provides a guard ring for on-line detection of polishing liquid state, which comprises a guard ring body, a polishing pad is arranged below the guard ring body, the polishing pad is fixed on a rotary table, a polishing liquid tank is arranged above the polishing pad, the guard ring body is connected with a connecting seat through a fixing seat, a controller is arranged on the connecting seat, the connecting seat is connected with an external power assembly, the power assembly, the polishing liquid tank and the rotary table are electrically connected with the controller; a plurality of liquid inlet holes for allowing the polishing liquid to enter the inside of the guard ring body are arranged at the bottom of the guard ring body, and a plurality of ultrasonic detection assemblies for detecting the polishing liquid entering the inside of the guard ring body through the liquid inlet holes are arranged inside the guard ring body.

[0005] Preferably, the ultrasonic detection assembly comprises an ultrasonic probe, the ultrasonic probe is electrically connected with the controller, a plurality of mounting holes for mounting the ultrasonic probe are arranged inside the guard ring body, and the mounting holes are distributed in a circumferential array on the upper surface of the guard ring body.

[0006] Preferably, the mounting holes are located directly above the liquid inlet holes, and there are 6-12 mounting holes; the frequency of the ultrasonic probe is 25KHz-40KHz, and the ultrasonic probe is fixedly glued in the mounting hole.

[0007] Preferably, a cover is arranged above the mounting hole, the cover is fixedly connected with the retainer body, and the cover is provided with a avoiding hole through which the probe of the ultrasonic probe passes.

[0008] Preferably, the retainer body is made of corrosion-resistant engineering plastic, the inner diameter of the retainer body is matched with the outer diameter of the wafer, the retainer body is provided with a plurality of first connecting holes, the fixing seat is provided with a plurality of second connecting holes, and the retainer body is fixedly connected with the fixing seat through the first connecting holes, the second connecting holes and the screws.

[0009] Preferably, the connecting seat is provided with a plurality of wire passing holes, the wire passing holes correspond to the mounting holes one by one, the upper surface of the connecting seat is provided with wire grooves distributed in a radial manner, and the signal line connected with the ultrasonic probe and the controller is located in the wire grooves.

[0010] Preferably, the top of the wire passing hole is provided with a cover for plugging the wire passing hole, the center of the cover is provided with a center hole in communication with the wire passing hole, the top end of the cover is provided with a connecting groove, the center hole is in communication with the wire groove through the connecting groove, and the signal line enters the wire groove through the center hole and the connecting groove.

[0011] Based on the detection method of the retainer for detecting the state of the polishing liquid on line, the method comprises the following steps:

[0012] S1, calibrating the retainer for detecting the state of the polishing liquid on line;

[0013] S2, the turntable drives the polishing pad to rotate, the wafer is placed in the retainer body, the power assembly drives the retainer body and the wafer to approach the polishing pad, and the power assembly drives the retainer body and the wafer to move on the polishing pad to polish the wafer;

[0014] S3, the polishing liquid in the polishing liquid tank flows onto the polishing pad, the polishing liquid enters the retainer body through the liquid inlet hole arranged on the bottom surface of the retainer body, the transmitting end of the ultrasonic probe arranged on the retainer body sends a detection signal to the polishing liquid in the liquid inlet hole, the receiving end of the ultrasonic probe receives the signal, and the received signal is amplified and transmitted to the controller;

[0015] S4, the signal processing module in the controller processes the signal, extracts characteristic information related to the concentration, particle distribution and liquid level of the polishing liquid, compares the characteristic information with the standard value pre-stored in the comparison module of the controller, and the alarm module of the controller alarms according to the comparison result and adjusts the concentration, particle distribution and liquid level of the polishing liquid.

[0016] Preferably, the alarm module performs a three-level response: when the concentration, particle distribution, and liquid level of the polishing slurry deviate from the standard values ​​by 5%-10%, a warning is issued; when the deviation of the concentration, particle distribution, and liquid level of the polishing slurry from the standard values ​​is greater than 10% but not greater than 20%, an alarm is issued; and when the deviation of the concentration, particle distribution, and liquid level of the polishing slurry from the standard values ​​is greater than 20%, an emergency shutdown is initiated.

[0017] The advantages and positive effects of the online detection ring and detection method for polishing fluid described in this invention are as follows: By uniformly setting ultrasonic probes on the ring body, with the ultrasonic probes located directly above the inlet hole, the concentration, particle distribution, and liquid level of the polishing fluid entering the ring body can be detected in real time, which is beneficial to improving the polishing effect and yield of wafers.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the retaining ring for online detection of the polishing fluid state according to an embodiment of the present invention;

[0020] Figure 2 This is a partial structural schematic diagram of the retaining ring for online detection of the polishing fluid state according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the ultrasonic probe installation structure for the retaining ring used for online detection of the polishing fluid state according to an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of the ultrasonic probe mounting cross-section structure of the retaining ring for online detection of the polishing fluid state according to an embodiment of the present invention;

[0023] Figure 5 This is a partial structural diagram of the ultrasonic probe installation for the retaining ring used in online detection of the polishing fluid state according to an embodiment of the present invention;

[0024] Figure 6 This is a three-dimensional structural diagram of the retaining ring body for online detection of polishing fluid status according to an embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of the three-dimensional structure of the sealing plate of the protective ring for online detection of the polishing fluid state according to an embodiment of the present invention;

[0026] Figure 8 This is a three-dimensional structural diagram of the retaining ring fixing seat for online detection of polishing fluid status according to an embodiment of the present invention;

[0027] Figure 9 This is a top view schematic diagram of the fixing seat of the retaining ring for online detection of polishing fluid status according to an embodiment of the present invention;

[0028] Figure 10 Fig. 2 is a sectional view of the fixed seat of the retainer for on-line detection of the state of polishing liquid according to an embodiment of the present application;

[0029] Figure 11 Fig. 3 is a perspective view of the cover of the retainer for on-line detection of the state of polishing liquid according to an embodiment of the present application;

[0030] Figure 12 Fig. 4 is a sectional view of the cover of the retainer for on-line detection of the state of polishing liquid according to an embodiment of the present application.

[0031] Reference numerals

[0032] 1, retainer body; 2, fixed seat; 3, connecting seat; 4, controller; 5, polishing liquid tank; 6, polishing pad; 7, turntable; 8, liquid inlet hole; 9, cover; 10, first connecting hole; 11, ultrasonic probe; 12, mounting hole; 13, avoiding hole; 14, wire passing hole; 15, wire groove; 16, second connecting hole; 17, cover; 18, center hole; 19, connecting groove. DETAILED DESCRIPTION

[0033] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "provided", "mounted", "connected" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] In the present application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art to which the present application belongs. If there is any inconsistency, the meaning described in the specification or derived from the content described in the specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0035] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0036] As Figures 1-12The guard ring for online detection of polishing liquid state is shown. The guard ring body 1 is provided below with a polishing pad 6 fixed on a turntable 7, and the turntable 7 drives the polishing pad 6 to rotate. The polishing pad 6 is provided above with a polishing liquid tank 5 for injecting polishing liquid to the upper side of the polishing pad 6 for polishing a wafer. The guard ring body 1 is fixedly connected with a connecting seat 3 through a fixing seat 2. The connecting seat 3 is provided with a controller 4. The connecting seat 3 is connected with an external power assembly, which can be an existing rotating assembly or a lifting assembly, for driving the guard ring structure to rotate and lift, so as to place or remove the wafer on or from the polishing pad 6. The power assembly, the polishing liquid tank 5 and the turntable 7 are electrically connected with the controller 4, and the flow of the polishing liquid in the polishing liquid tank 5, the rotation and lifting of the power assembly and the rotation of the turntable 7 are controlled through the controller 4.

[0037] The bottom of the guard ring body 1 is provided with a plurality of liquid inlet holes 8 for allowing the polishing liquid to enter the inside of the guard ring, and the liquid inlet holes 8 are uniformly distributed in a circumferential array at the bottom of the guard ring. The inside of the guard ring body 1 is provided with a plurality of ultrasonic detection assemblies for detecting the polishing liquid entering the inside of the guard ring through the liquid inlet holes 8.

[0038] The ultrasonic detection assembly includes an ultrasonic probe 11 electrically connected with the controller 4. The ultrasonic probe 11 is a waterproof probe with an integrated transmitting end and receiving end. The transmitting end emits ultrasonic signals of a specific frequency into the polishing liquid, and the power of the ultrasonic probe 11 is 25KHz-40KHz. The receiving end is used for receiving the ultrasonic signals propagated through the polishing liquid, and the concentration, liquid level and particle distribution of the polishing liquid are obtained by analyzing the differences between the transmitted signals and the received signals, such as signal attenuation, frequency shift and phase change.

[0039] The concentration detection principle of the ultrasonic wave is that when the ultrasonic wave propagates in the polishing liquid, the attenuation degree is related to the concentration of the abrasive particles in the polishing liquid. The higher the concentration is, the greater the attenuation of the ultrasonic wave is. The received ultrasonic attenuation signal is converted into the concentration value of the polishing liquid by establishing a mathematical model of the ultrasonic attenuation and the concentration of the polishing liquid. For example, the concentration of the polishing liquid is accurately measured by using a modified model of Lambert-Beer law and combining experimental data for calibration.

[0040] The particle distribution detection principle of the ultrasonic wave is that the scattering and reflection characteristics of the ultrasonic wave are different for abrasive particles of different particle sizes. The particle size distribution of the abrasive particles in the polishing liquid is inferred by analyzing the frequency components and phase changes in the received signals. For example, the particle distribution ratio in different particle size intervals is obtained by processing the received signals by using a frequency spectrum analysis technology and a phase difference detection algorithm.

[0041] The liquid level detection principle of the ultrasonic wave is as follows: the ultrasonic wave T port emits an ultrasonic wave signal to the polishing liquid surface, and the signal is reflected by the polishing liquid surface and received by the ultrasonic wave R port. According to the propagation time and speed of the ultrasonic wave, the distance between the polishing liquid surface and the retainer body 1 can be calculated, and thus the liquid level height of the polishing liquid can be obtained.

[0042] The inside of the retainer body 1 is provided with a plurality of mounting holes 12 for mounting the ultrasonic wave probe 11, and the mounting holes 12 are distributed in a circumferential array on the upper surface of the retainer body 1. The mounting holes 12 are located directly above the liquid inlet hole 8, and the mounting holes 12 are provided with 6-12 holes. The hole diameter of the mounting hole 12 is slightly larger than the outer diameter of the ultrasonic wave probe 11, and the ultrasonic wave probe 11 is glued and fixed in the mounting hole 12, thereby improving the stability of the fixing of the ultrasonic wave probe 11. The number of liquid inlet holes 8 is twice the number of mounting holes 12.

[0043] A cover 9 is arranged above the mounting hole 12, and the cover 9 is fixedly connected with the retainer body 1. The cover 9 protects the ultrasonic wave probe 11, reduces the influence of the external environment on the ultrasonic wave probe 11, improves the stability of the ultrasonic wave probe 11, and improves the detection accuracy. The cover 9 is provided with a avoiding hole 13 for the probe of the ultrasonic wave probe 11 to pass through.

[0044] The retainer body 1 is made of corrosion-resistant engineering plastic, the inner diameter of the retainer body 1 is matched with the outer diameter of the wafer, and the deviation is controlled within ±0.05mm, so as to ensure that the wafer is closely attached to the retainer. A plurality of first connecting holes 10 are arranged on the retainer body 1, a plurality of second connecting holes 16 are arranged on the fixed seat 2, and the retainer body 1 is fixedly connected with the fixed seat 2 through the first connecting hole 10, the second connecting hole 16 and the screw.

[0045] A plurality of wire passing holes 14 are arranged on the connecting seat 3, and the wire passing holes 14 correspond one by one to the mounting holes 12. The upper surface of the connecting seat 3 is provided with a plurality of wire grooves 15 arranged in a radial manner, and the signal line connected with the controller 4 passes through the wire passing hole 14 and is connected with the controller 4 along the wire groove 15.

[0046] The top of the wire passing hole 14 is provided with a cover 17 for plugging the wire passing hole 14. The center of the cover 17 is provided with a center hole 18 in communication with the wire passing hole 14, and the top end of the cover 17 is provided with a connecting groove 19, and the center hole 18 is in communication with the wire groove 15 through the connecting groove 19. The signal line enters the wire groove 15 through the center hole 18 and the connecting groove 19. The hole diameter of the center hole 18 is slightly larger than the outer diameter of the signal line, and the signal line is fixed by the cover 17, which reduces the displacement of the signal line during work, reduces the influence of the signal line on the ultrasonic wave probe 11, and protects the signal line, thereby ensuring the stable and reliable transmission of the signal.

[0047] Based on the above-mentioned detection method of the retainer for online detection of the polishing liquid state, the following steps are included:

[0048] S1, calibrate the guard ring for online detection of the polishing liquid state.

[0049] A standard polishing liquid sample library with known parameters (covering 5 concentration gradients, 3 particle distribution types, and 4 liquid level heights) is used to perform "point-to-point" calibration of the ultrasonic detection assembly.

[0050] The signal attenuation data at different temperatures and pressures are collected to correct the detection results, ensuring the accuracy of the detection results at different temperatures and pressures.

[0051] During continuous polishing, a small amount of standard test liquid is injected every two hours to test the accuracy of the detection results of the ultrasonic probe 11. If the deviation of the test results exceeds 5% for three consecutive times, the guard ring structure is repaired.

[0052] S2, the turntable 7 drives the polishing pad 6 to rotate, the wafer is placed inside the guard ring body 1, the power assembly drives the guard ring body 1 and the wafer to approach the polishing pad 6, and the power assembly drives the guard ring body 1 and the wafer to move on the polishing pad 6 to polish the wafer.

[0053] S3, the polishing liquid in the polishing liquid tank 5 flows onto the polishing pad 6, the polishing liquid enters the inside of the guard ring body 1 through the liquid inlet hole 8 provided on the bottom surface of the guard ring body 1, the emitting end of the ultrasonic probe 11 provided on the guard ring body 1 sends a detection signal to the polishing liquid in the liquid inlet hole 8, the receiving end of the ultrasonic probe 11 receives the signal and transmits the amplified received signal to the controller 4;

[0054] S4, the signal processing module in the controller 4 performs filtering, amplification, frequency spectrum analysis, and other processing on the signal, extracts characteristic information related to the concentration, particle distribution, and liquid level of the polishing liquid, and then compares it with the standard value pre-stored in the comparison module of the controller 4; the alarm module of the controller 4 alarms according to the comparison result, and adjusts the concentration, particle distribution, and liquid level of the polishing liquid.

[0055] The alarm module performs three-level response, when the deviation of the concentration, particle distribution, and liquid level of the polishing liquid from the standard value is within 5%-10%, a pre-warning is given, the concentration and particle size of the polishing liquid are adjusted, and the flow of the polishing liquid is controlled. When the deviation of the concentration, particle distribution, and liquid level of the polishing liquid from the standard value is greater than 10% and not greater than 20%, an alarm is given, the automatic addition of the polishing liquid is stopped, the polishing power is limited, and the concentration and particle size of the polishing liquid are adjusted. When the deviation of the concentration, particle distribution, and liquid level of the polishing liquid from the standard value is greater than 20%, an emergency stop is performed. Thus, the polishing effect of the wafer is ensured.

[0056] The guard ring structure is tested every 8 hours during use, standard liquid is injected, and whether the concentration, particle size distribution and liquid level deviation are ≤2% is verified. A deep function test is performed every week, abnormal working conditions (such as sudden change of particle concentration and sharp drop of liquid level) are simulated, and the alarm response time (≤1s) is verified. A full system calibration test is performed every month: the reference calibration process is repeated, and the parameter drift caused by long-term operation is corrected.

[0057] Therefore, the guard ring and the detection method for detecting the state of the polishing liquid online can solve the problem that the existing wafer polishing equipment cannot detect the polishing liquid in real time, thereby affecting the wafer polishing effect.

[0058] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A retaining ring for online detection of polishing fluid status, comprising a retaining ring body, a polishing pad disposed below the retaining ring body, the polishing pad being fixed on a turntable, and a polishing fluid tank disposed above the polishing pad, characterized in that: The protective ring body is connected to the connecting seat via a fixed seat. The connecting seat is equipped with a controller and is connected to an external power unit. The power unit, polishing fluid tank, and turntable are all electrically connected to the controller. The bottom of the protective ring body is provided with several inlet holes for the polishing fluid to enter the interior of the protective ring. The interior of the protective ring body is provided with several ultrasonic detection components for detecting the polishing fluid entering the interior of the protective ring through the inlet holes. The ultrasonic testing component includes an ultrasonic probe, which is electrically connected to the controller. The inner surface of the protective ring body has several mounting holes for mounting the ultrasonic probe, which are distributed in a circumferential array on the upper surface of the protective ring body. The mounting hole is located directly above the liquid inlet. The ultrasonic probe is used to obtain the concentration, level, and particle distribution of the polishing slurry.

2. The protective ring for online detection of polishing fluid status according to claim 1, characterized in that: The mounting holes are provided in 6-12 locations; the frequency of the ultrasonic probe is 25KHz-40KHz, and the ultrasonic probe is glued and fixed in the mounting holes.

3. The protective ring for online detection of polishing fluid status according to claim 1, characterized in that: A cover is provided above the mounting hole. The cover is fixedly connected to the protective ring body. The cover is provided with a clearance hole for the probe of the ultrasonic probe to pass through.

4. The protective ring for online detection of polishing fluid status according to claim 1, characterized in that: The retaining ring body is made of corrosion-resistant engineering plastic. The inner diameter of the retaining ring body is adapted to the outer diameter of the wafer. The retaining ring body is provided with several first connecting holes, and the fixing base is provided with several second connecting holes. The retaining ring body is fixedly connected to the fixing base through the first connecting holes, the second connecting holes, and screws.

5. A retaining ring for online detection of polishing fluid status according to claim 1, characterized in that: The connector has several wire holes, which correspond one-to-one with the mounting holes. The upper surface of the connector has radially distributed wire grooves, and the signal lines connecting the ultrasonic probe and the controller are located in the wire grooves.

6. A retaining ring for online detection of polishing fluid status according to claim 5, characterized in that: The top of the wire hole is provided with a protective cover to seal the wire hole. The center of the protective cover is provided with a central hole that communicates with the wire hole. The top of the protective cover is provided with a connecting groove. The central hole communicates with the wire groove through the connecting groove. The signal line enters the wire groove through the central hole and the connecting groove.

7. A method for detecting the state of a retaining ring based on the online detection of polishing fluid according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Calibrate the retaining ring for online detection of polishing fluid status; S2. The turntable drives the polishing pad to rotate, placing the wafer into the inside of the guard ring body. The power component drives the guard ring body and the wafer to approach the polishing pad. The power component drives the guard ring body and the wafer to move on the polishing pad to polish the wafer. S3. The polishing liquid in the polishing liquid tank flows into the polishing pad. The polishing liquid enters the interior of the protective ring body through the liquid inlet hole set on the bottom surface of the protective ring body. The transmitting end of the ultrasonic probe set on the protective ring body sends a detection signal to the polishing liquid in the liquid inlet hole. The receiving end of the ultrasonic probe receives the signal, amplifies the received signal, and transmits it to the controller. S4. The signal processing module in the controller processes the signal and extracts feature information related to the concentration, particle distribution and liquid level of the polishing fluid; then it compares it with the standard value stored in the comparison module of the controller; the alarm module of the controller alarms according to the comparison result and adjusts the concentration, particle distribution and liquid level of the polishing fluid.

8. The detection method according to claim 7, characterized in that: The alarm module executes a three-level response: when the concentration, particle distribution, and liquid level of the polishing slurry deviate from the standard values ​​by 5%-10%, a warning is issued; when the deviation of the concentration, particle distribution, and liquid level of the polishing slurry from the standard values ​​is greater than 10% but not greater than 20%, an alarm is issued; and when the deviation of the concentration, particle distribution, and liquid level of the polishing slurry from the standard values ​​is greater than 20%, an emergency shutdown is initiated.

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