Device for detecting polishing pad and improving double-sided polishing flatness and control method thereof

Abstract

The invention relates to a device for detecting a polishing pad and improving double-face polishing flatness and a control method thereof, and belongs to the technical field of silicon wafer machining, the device comprises a polishing fixed disc, the polishing pad is arranged on the polishing fixed disc, a mechanical arm is arranged on the outer side of the polishing fixed disc, and a detection tool is arranged between the lower end of the mechanical arm and polishing cloth. The detection tool comprises a tool protection shell, a plurality of laser microscopes which face downwards to detect the polishing pad are arranged in the tool protection shell, and thickness measurement sensors are arranged on the side edges of the laser microscopes. The device has the characteristics of simple structure, convenience in operation and good running stability. The problems of non-uniform removal in the polishing process and flatness fluctuation in the machining process are solved. The polishing pad is subjected to various detections, and the flatness and stability of silicon wafer processing are improved through detection evaluation.

Description

Technical Field

[0001] The invention relates to the technical field of silicon wafer processing, and in particular to a device for detecting a polishing pad and improving double-sided polishing flatness, and a control method thereof. Background Art

[0002] Information technology has become a powerful driving force for the social and economic development of countries around the world, driving society to develop at an unprecedented speed. The development of information technology relies on the rapid development of large-scale integrated circuit (IC) technology. Integrated circuits (IC) are electronic devices made on semiconductor chips (silicon chips) or dielectric substrates using certain processes. According to statistics, 90% of semiconductor devices are made of silicon materials.

[0003] As the diameter of silicon wafers becomes larger and the size of electronic devices becomes smaller, higher technical requirements are placed on the flattening of the silicon substrate surface. Chemical mechanical polishing has become a key technology for high flattening in large-scale integrated circuit manufacturing.

[0004] Double-sided chemical mechanical polishing is currently one of the most effective technical means to achieve high flatness for large-size silicon wafers. However, in the actual production and processing process, double-sided polishing is technically complex and has many influencing factors. Chemical and mechanical actions alternate with each other, and multiple variables interact with each other. Slight changes in the variables will affect the relationship between the silicon wafer, the polishing liquid, and the polishing pad, thereby affecting the final flatness of the silicon wafer. Among the many influencing factors, the impact of the polishing pad is the most difficult to control and measure. Usually, the material used for the polishing pad is polyurethane foam or a combination of non-woven fabric and resin material. These materials will undergo undetectable changes due to pressure, temperature and polishing liquid during the processing process, resulting in unstable flatness of the processed silicon wafer or failure to meet the requirements of smaller devices. Summary of the invention

[0005] The present invention mainly solves the deficiencies in the prior art and provides a device for detecting polishing pads and improving the flatness of double-sided polishing and a control method thereof, which has the characteristics of simple structure, convenient operation and good running stability. The problem of uneven removal during polishing and flatness fluctuation during processing is solved. The polishing pad is subjected to a variety of tests, and the flatness and stability of silicon wafer processing are improved through test evaluation.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions: A device for detecting a polishing pad and improving the flatness of double-sided polishing includes a polishing plate, a polishing pad is arranged on the polishing plate, a mechanical arm is arranged outside the polishing plate, and a detection tool is arranged between the lower end of the mechanical arm and the polishing cloth. The detection tool includes a tool protection shell, and a plurality of laser microscopes facing downward to detect the polishing pad are arranged in the tool protection shell, and thickness measurement sensors are arranged on the sides of the laser microscopes.

[0007] Preferably, the processing tracks of the polishing pad on the polishing plate are inner circle, middle circle and outer circle from inside to outside. The number of laser microscopes and thickness measurement sensors in the tool protection housing is 3, and the laser microscopes and thickness measurement sensors detect the inner circle, middle circle and outer circle in turn.

[0008] Preferably, the radial dimensions of the inner ring, middle ring and outer ring of the polishing pad are 100 mm, 330 mm and 660 mm respectively.

[0009] Preferably, a connecting seat is provided between the detection tool and the mechanical arm.

[0010] Preferably, the tool protection shell is made of PP material, which is corrosion-resistant and waterproof.

[0011] A control method for detecting a polishing pad and improving a double-sided polishing flatness device comprises the following steps: Step 1: Measure the polishing cloth before dressing and start the robot arm to move the detection tool over the polishing pad.

[0012] Step 2: Place the center point of the laser microscope on the inner circle, middle circle and outer circle respectively.

[0013] Step 3: Use a laser microscope to measure the 3D topography of the polishing pad surface and detect the surface roughness of the polishing cloth.

[0014] Step 4: The thickness measurement sensor measures the distance between the polishing pad surface and the polishing platen to obtain the thickness distribution of the annular areas of the inner circle, middle circle and outer circle.

[0015] Step 5: Adjust the equipment dressing pressure through the measured data, and use the thickness of the polishing pad to control the unevenness during the polishing process.

[0016] Preferably, the polishing pad surface topography is measured to check the surface finishing uniformity and polishing residue accumulation, so that the polishing pad is always kept in the best condition.

[0017] Preferably, during the processing of silicon wafers, the porous structure on the surface of the polishing pad will become glazed after long-term mechanical action, and the removal rate will be reduced. The surface glazing condition is measured by measuring the surface roughness of the polishing cloth, and the grinding wheel is used for timely dressing to maintain the silicon wafer removal rate.

[0018] Preferably, the thickness measuring sensor has a detection accuracy of micrometers, ranging from 10 mm to 100 μm, and is measured by eddy current induction.

[0019] Preferably, the direction of the eddy current in the polishing pad is opposite to the current of the AC magnetic field coil applied to the test piece. The AC magnetic field generated by the eddy current also generates alternating magnetic lines of force, which induce a reaction current when passing through the excitation coil; if the eddy current in the polishing pad changes, the reaction current also changes, and the change in the eddy current is measured to obtain the detection information of the polishing pad.

[0020] The present invention can achieve the following effects: The present invention provides a device for detecting a polishing pad and improving the flatness of double-sided polishing and a control method thereof. Compared with the prior art, the device has the characteristics of simple structure, convenient operation and good running stability. The problem of uneven removal during polishing and flatness fluctuation during processing is solved. The polishing pad is subjected to a variety of tests, and the flatness and stability of silicon wafer processing are improved through test evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 It is a measurement schematic diagram of the present invention.

[0023] Figure 3 It is a schematic diagram of the structure of the detection tool of the present invention.

[0024] In the figure: polishing pad 1, detection tool 2, connecting seat 3, mechanical arm 4, polishing plate 5, outer ring 6, middle ring 7, inner ring 8, tool protection shell 9, laser microscope 10, thickness measurement sensor 11. DETAILED DESCRIPTION

[0025] The technical solution of the invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0026] Example: Figure 1 , Figure 2 and Figure 3As shown, a device for detecting a polishing pad and improving the flatness of double-sided polishing includes a polishing plate 5, a polishing pad 1 is arranged on the polishing plate 5, a mechanical arm 4 is arranged outside the polishing plate 5, a detection tool 2 is arranged between the lower end of the mechanical arm 4 and the polishing cloth 1, and a connecting seat 3 is arranged between the detection tool 2 and the mechanical arm 4. The detection tool 2 includes a tool protection shell 9, and the tool protection shell 9 is made of PP material, which has the characteristics of corrosion resistance and waterproof. A plurality of laser microscopes 10 are arranged in the tool protection shell 9 for detecting the polishing pad 1 downward, and thickness measurement sensors 11 are arranged on the sides of the laser microscopes 10. The processing tracks of the polishing pad 1 on the polishing plate 5 are inner circle 8, middle circle 7 and outer circle 6 from inside to outside. There are three laser microscopes 10 and thickness measurement sensors 11 in the tool protection shell 9, and the laser microscopes 10 and thickness measurement sensors 11 correspond to the inner circle 8, middle circle 7 and outer circle 6 for detection in turn. The radial dimensions of the inner ring 8, the middle ring 7 and the outer ring 6 of the polishing pad 1 are 100 mm, 330 mm and 660 mm respectively.

[0027] A control method for detecting a polishing pad and improving a double-sided polishing flatness device comprises the following steps: Step 1: Measure the polishing cloth 1 before trimming, and start the robot arm 4 to move the detection tool 2 above the polishing pad 1.

[0028] Step 2: Align the center point of the laser microscope 10 to the inner circle 8, the middle circle 7 and the outer circle 6 respectively.

[0029] Step 3: Use laser microscope 10 to measure the 3D topography of the polishing pad 1 surface. The surface topography of the polishing pad 1 is used to check the surface finishing uniformity and polishing residue accumulation, so that the polishing pad 1 is always in the best condition. Detect the surface roughness of the polishing cloth. During the silicon wafer processing, the porous structure on the surface of the polishing pad 1 will be glazed after a long period of mechanical action. At this time, the removal rate will be reduced. The surface glazing is measured by measuring the surface roughness of the polishing cloth, and the grinding wheel is used for timely dressing to maintain the silicon wafer removal rate.

[0030] Step 4: The thickness measuring sensor 11 measures the distance between the surface of the polishing pad 1 and the polishing plate 5 to obtain the thickness distribution of the annular areas of the inner ring 8, the middle ring 7 and the outer ring 6. The thickness measuring sensor 11 has a detection accuracy of microns, ranging from 10mm to 100μm, and is measured by eddy current induction.

[0031] The direction of the eddy current in the polishing pad 1 is opposite to the current of the AC magnetic field coil applied to the test piece. The AC magnetic field generated by the eddy current also generates alternating magnetic lines of force, which induce a reaction current when passing through the excitation coil; if the eddy current in the polishing pad 1 changes, the reaction current also changes, and the change of the eddy current is measured, thereby obtaining the detection information of the polishing pad 1.

[0032] Step 5: Adjust the equipment dressing pressure through the measured data, and use the thickness of the polishing pad 1 to control the unevenness during the polishing process.

[0033] The thickness, roughness and surface morphology of the polishing pad are measured to solve the problem of uneven removal during polishing and the flatness fluctuation caused by uncertain factors during processing; processing high-flatness silicon wafers plays a decisive role in the exposure stability of high-process chips. The polished wafer GBIR obtained by the processing method adjusted by this detection technology is less than 100nm; SFQR (26*8) is less than 10nm; ESFQR (35EE2) is less than 15nm.

[0034] In summary, the device for detecting polishing pads and improving double-sided polishing flatness and the control method thereof have the characteristics of simple structure, convenient operation and good running stability. The problem of uneven removal during polishing and flatness fluctuation during processing is solved. The polishing pad is subjected to a variety of tests, and the flatness and stability of silicon wafer processing are improved through test evaluation.

[0035] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A device for detecting a polishing pad and improving the flatness of double-sided polishing, comprising a polishing plate (5), on which a polishing pad (1) is arranged, characterized in that: A mechanical arm (4) is arranged outside the polishing plate (5), and a detection tool (2) is arranged between the lower end of the mechanical arm (4) and the polishing cloth (1); the detection tool (2) comprises a tool protection shell (9), and a plurality of laser microscopes (10) facing downward to detect the polishing pad (1) are arranged inside the tool protection shell (9), and thickness measurement sensors (11) are arranged on the sides of the laser microscopes (10).

2. The device for detecting polishing pads and improving double-sided polishing flatness according to claim 1, characterized in that: The processing tracks of the polishing pad (1) on the polishing platen (5) are, from the inside to the outside, an inner circle (8), a middle circle (7), and an outer circle (6); the number of the laser microscopes (10) and the thickness measurement sensors (11) in the tool protection housing (9) is three, and the laser microscopes (10) and the thickness measurement sensors (11) perform detection corresponding to the inner circle (8), the middle circle (7), and the outer circle (6) in sequence.

3. The device for detecting polishing pads and improving double-sided polishing flatness according to claim 2, characterized in that: The radial dimensions of the inner ring (8), middle ring (7) and outer ring (6) of the polishing pad (1) are 100 mm, 330 mm and 660 mm respectively.

4. The device for detecting polishing pads and improving double-sided polishing flatness according to claim 1, characterized in that: A connecting seat (3) is provided between the detection tool (2) and the mechanical arm (4).

5. The device for detecting polishing pads and improving double-sided polishing flatness according to claim 1, characterized in that: The tool protection housing (9) is made of PP material and has corrosion-resistant and waterproof properties.

6. A control method for detecting a polishing pad and improving the double-sided polishing flatness device according to claim 2, characterized in that The steps are as follows: Step 1: measuring the polishing cloth (1) before trimming, and starting the robot arm (4) to move the detection tool (2) above the polishing pad (1); Step 2: Align the center point of the laser microscope (10) to the inner circle (8), the middle circle (7) and the outer circle (6); Step 3: Using a laser microscope (10) to measure the 3D topography of the surface of the polishing pad (1) to detect the surface roughness of the polishing cloth; Step 4: The thickness measuring sensor (11) measures the distance between the surface of the polishing pad (1) and the polishing plate (5) to obtain the thickness distribution of the annular regions of the inner ring (8), the middle ring (7) and the outer ring (6); Step 5: The equipment dressing pressure is adjusted by measuring the data, and the thickness of the polishing pad (1) is adjusted to control the unevenness during the polishing process.

7. The control method for detecting a polishing pad and improving the double-sided polishing flatness device according to claim 6, characterized in that: Measuring the surface topography of the polishing pad (1) is used to check the surface finishing uniformity and the accumulation of polishing residues, so that the polishing pad (1) is always kept in the best condition.

8. The control method for detecting a polishing pad and improving the double-sided polishing flatness device according to claim 6, characterized in that: During the processing of silicon wafers, the porous structure of the surface of the polishing pad (1) will be glazed after long-term mechanical action. At this time, the removal rate will be reduced. The surface glazing condition is measured by measuring the surface roughness of the polishing cloth, and the grinding wheel is used for timely dressing to maintain the silicon wafer removal rate.

9. The control method for detecting a polishing pad and improving the double-sided polishing flatness device according to claim 6, characterized in that: The thickness measuring sensor (11) has a detection accuracy of micrometers, ranging from 10 mm to 100 μm, and is measured by eddy current induction.

10. The control method for detecting a polishing pad and improving the double-sided polishing flatness device according to claim 9, characterized in that: The direction of the eddy current in the polishing pad (1) is opposite to the current of the coil applying the alternating magnetic field to the test piece. The alternating magnetic field generated by the eddy current also generates alternating magnetic lines of force, which in turn induce a reaction current when passing through the exciting coil. If the eddy current in the polishing pad (1) changes, the reaction current also changes. The change in the eddy current is measured, thereby obtaining detection information of the polishing pad (1).

Images