Polishing head and polishing system

Abstract

The embodiment of the invention discloses a polishing head and a polishing system.The polishing head can comprise an annular maintaining part and a ventilation part, and the annular maintaining part is used for limiting a wafer in the radial direction of the wafer when the polishing head bears the wafer; the ventilation part is arranged on the annular holding part, so that gas can enter the annular holding part through the ventilation part under the condition that the wafer holding part is in contact with the polishing pad.

Description

Technical Field

[0001] The disclosed embodiments relate to the field of semiconductor manufacturing technology, and more particularly to a polishing head and a polishing system. Background Art

[0002] In the chemical mechanical polishing (CMP) process of wafer manufacturing, in order to improve the quality of the nano-topography of the wafer surface and prevent the generation of related imprints, a grooveless polishing pad is usually used for polishing to prevent the grooves from significantly deteriorating the nano-topography of the wafer.

[0003] However, the surface of the grooveless polishing pad is relatively flat, and the silicon wafer is firmly adsorbed on the polishing pad by the surface tension of the water under the action of the slurry (which is mostly composed of water). As a result, wafers often fall off and fragments occur when the polishing head is raised after polishing, seriously affecting the production and manufacturing of silicon wafers. Summary of the invention

[0004] In view of this, the embodiments of the present disclosure are intended to provide a polishing head and a polishing system that can solve the technical problem of wafer drop and fragmentation that often occurs during the polishing head lifting stage after polishing.

[0005] The technical solution of the embodiment of the present disclosure is implemented as follows: In a first aspect, an embodiment of the present disclosure provides a polishing head, comprising: An annular retaining member, used for limiting the position of the wafer in the radial direction of the wafer when the polishing head carries the wafer; The vent is arranged on the annular holder so that when the wafer holder is in contact with the polishing pad, gas can enter the annular holder through the vent.

[0006] In some examples, the vent includes: At least one through hole extends along a radial direction of the wafer.

[0007] In some examples, there are a plurality of through holes, and the plurality of through holes are evenly arranged in an array along the circumferential direction of the annular retaining member.

[0008] In some examples, the vent includes: At least one groove extends along one end surface of the annular retaining member toward the middle of the annular retaining member.

[0009] In some examples, the groove extends from an end surface of the annular holder away from the polishing head body to a middle of the annular holder.

[0010] In some examples, the polishing head further comprises: The adsorption film is provided, and one end surface of the annular retaining member is fixed to the adsorption film.

[0011] In some examples, a side of the annular retaining member away from the adsorption pad is made of elastic material.

[0012] In some examples, the annular retaining member is telescopically fixed to the adsorption film, so that the annular retaining member can limit the position of wafers of different thicknesses.

[0013] In some examples, the material of the annular retainer includes at least one of fiberglass, polyurethane, ceramic, plastic, and metal.

[0014] In a second aspect, an embodiment of the present disclosure provides a polishing system, comprising: The polishing head described in the first aspect and any one of the examples thereof; and The polishing pad is used to cooperate with the polishing head to polish the wafer.

[0015] The disclosed embodiments provide a polishing head and a polishing system; through the vent on the annular retaining member, gas can enter between the wafer and the polishing pad, reducing the pressure difference caused by the surface tension of water, so that the silicon wafer can be smoothly separated from the polishing pad after polishing is completed, reducing the risk of the silicon wafer falling and breaking when the polishing head is lifted. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a polishing device in the related art.

[0017] Figure 2 A schematic diagram of a sealed environment formed by polishing with a grooveless polishing pad provided in an embodiment of the present disclosure.

[0018] Figure 3 A schematic diagram of a pressure model provided in an embodiment of the present disclosure.

[0019] Figure 4 A schematic diagram of a polishing head provided in accordance with an embodiment of the present disclosure.

[0020] Figure 5 A schematic diagram of another polishing head provided in an embodiment of the present disclosure.

[0021] Figure 6 A schematic diagram of an annular retaining member provided in an embodiment of the present disclosure.

[0022] The above drawings show clear embodiments of the present disclosure, which will be described in more detail below. These drawings and text descriptions are not intended to limit the scope of the present disclosure in any way, but to illustrate the concepts of the present disclosure to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0023] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0024] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0025] Reference Figure 1 The polishing head 1 is composed of a polishing head body 21 and a polishing head detachable component 22 connected by buckles or screws, and the two together form a chamber with a certain sealing performance and high-precision controllable and adjustable pressure. The lower surface of the polishing head detachable component 22 is a membrane made of rubber or other materials, which performs air extraction or inflation during the CMP process to facilitate pressure regulation.

[0026] The adsorption pad 3 is composed of an adsorption film 31 made of various materials and an annular retainer 32. The adsorption film 31 has an adhesive layer on the back, which is tightly attached to the bottom of the polishing head detachable component 22. The front of the adsorption film 31 will adsorb and fix the back of the wafer 4 for polishing and transfer operations. The polishing pad 5 is laid on the polishing table 6 using the adhesive layer on the back and moves with the latter. The annular retainer 32 is used to limit the wafer in the radial direction of the wafer during the CMP process.

[0027] During the CMP process, the wafer 4 is placed upside down on the loading platform and sprayed with a small amount of water. The polishing head 1 with the adsorption pad 3 is pressed down onto the wafer 4, and the front side of the adsorption pad 3 is closely attached to the back side of the wafer 4 to fix it firmly.

[0028] Then it is transferred to the polishing area, the polishing head 1 rotates with the wafer 4 and applies a certain force to rotate, the slurry is continuously sprayed by the pipe onto the polishing pad 5 rotating with the polishing table 6, the front side of the wafer 4 contacts the polishing pad 5 for polishing, until the polishing is completed, the polishing head 1 is slowly lifted up and leaves the polishing pad 5 with the wafer 4 adsorbed and fixed on the adsorption pad 3.

[0029] In order to improve the quality of the nano-topography of the polished wafer, a grooveless polishing pad 5 is used to polish the wafer 4. Figure 2 Since the front side of the grooveless polishing pad 5 is composed of ultra-dense holes of micron size and is very flat as a whole, the polishing pad 5 is soaked in water during the polishing process, and the wafer 4 is pressed on the polishing pad 5 under a certain pressure. The annular retaining member 32 and the polishing pad 5 form a sealed environment under the infiltration of water to prevent external air from entering.

[0030] There is an extremely thin water film between the front side of the wafer 4 and the polishing pad 5. This water film will generate a huge force due to surface tension. The force is downward relative to the wafer 4. When the polishing head 1 is lifted, the wafer 4 must at least withstand two forces from the back and front sides of the wafer, making it very easy for the wafer 4 to fall off the adsorption pad 3 and even break into pieces.

[0031] The following is a simplified example to illustrate the cause of fragmentation. Figure 3 As shown, it is assumed that the water film thickness is about 5 microns, and the surface tension of water at room temperature is 0.073N / m instead of the surface tension of the polishing slurry liquid (because the majority of the polishing slurry is water). It is assumed that the contact angle between water and the wafer is 30°~40°. It is well known that in a balanced system, atmospheric pressure P0 = liquid pressure P1 + pressure P2 generated by surface tension. Using Young-Laplace equation, it can be calculated that P2 is approximately 10~30kPa. This pressure will cause the polishing head 1 to slowly lift up and leave the polishing pad 5 with the wafer 4 adsorbed and fixed on the adsorption pad 3. Due to pressure reasons, the wafer 4 is easily broken.

[0032] Based on this, the present disclosure first provides a new polishing head, referring to Figure 4 , may include an annular holder 32 and a vent 321, wherein the annular holder 32 is mainly used to fix the wafer 4 during the polishing process. The annular holder 32 holds the wafer 4 in a fixed position by contacting the wafer 4 so as to grind the single side of the wafer 4. During the CMP process, the annular holder 32 provides restriction in the radial direction of the wafer 4 through its annular structure to prevent the wafer 4 from shifting or vibrating under the high-speed rotation or pressure of the polishing head. The vent 321 allows gas (usually air or a specific gas) to circulate, which helps to control the pressure between the polishing pad 5 and the wafer 4, as well as the temperature of the polishing pad 5 during the CMP process. The gas entering through the vent 321 can be used to adjust the pressure inside the annular holder 32. This pressure regulation is essential for controlling the contact pressure between the wafer 4 and the polishing pad 5 to ensure the uniformity and efficiency of the polishing process.

[0033] In some examples, the annular retainer 32 may be made of a variety of materials, which are required to have properties such as high wear and corrosion resistance, low vibration characteristics, material stability and purity, etc. For example, the materials of the annular retainer 32 include but are not limited to glass fiber, polyurethane, ceramic, plastic and metal. Each material has its own unique advantages, such as the high strength and light weight of glass fiber, the excellent elasticity and wear resistance of polyurethane, the heat resistance and chemical resistance of ceramic, the lightness and cost-effectiveness of plastic, and the high strength and impact resistance of metal.

[0034] The annular retaining member 32 may be provided with a vent 321. In some examples, the vent 321 may include at least one through hole. Figure 4 The through hole extends in the radial direction of the wafer 4, allowing the airflow to flow from the outer surface of the annular holder 32 to the inner surface of the annular holder 32. When the wafer 4 holder is in contact with the polishing pad 5, the gas can enter the inside of the annular holder 32, thereby reducing the pressure difference caused by the surface tension of the water, helping the wafer 4 to be separated from the polishing pad 5 smoothly after polishing, and reducing the risk of the wafer 4 falling and fragments when the polishing head is lifted.

[0035] The size of the through hole can be designed according to the gas flow requirement and the strength of the annular retainer 32. Too large an aperture may reduce the structural strength of the annular retainer 32, while too small an aperture may limit the gas flow and affect the pressure regulation efficiency. Optionally, the aperture can be set to 0.05mm to 0.2mm, for example, it can be 0.05mm, 0.07mm, 0.1mm, 0.15mm, 0.18mm, 0.2mm, etc., which is negatively correlated with the number of apertures, that is, the smaller the aperture, the more holes, and the larger the aperture, the smaller the number of holes, so as to ensure the structural strength of the annular retainer 32 while ensuring the air intake.

[0036] Multiple through holes are evenly arranged in an array along the circumferential direction of the annular retainer 32 to ensure that the entire wafer 4 area can effectively receive gas and avoid uneven pressure during polishing. The cross-sectional shape of the through hole can be circular, elliptical or any other shape suitable for fluid dynamics. The choice of shape may affect the efficiency of gas flow.

[0037] In some examples, multiple through holes can be evenly arranged in the circumferential direction of the annular retaining member 32, and the density of the through holes gradually increases along the direction of the annular retaining member 32 away from the polishing head body 21, so as to ensure that the strength of the end of the annular retaining member 32 close to the adsorption film 31 is greater, so that the annular retaining member can be more firmly fixed on the adsorption film 31. At the same time, the air intake volume close to the end of the polishing pad 5 can be increased, and the pressure difference caused by the surface tension of water can be further reduced, so that the silicon wafer can be smoothly separated from the polishing pad after polishing is completed, reducing the risk of silicon wafer falling and fragmentation when the polishing head is lifted.

[0038] In some examples, the through hole can be manufactured by mechanical drilling, laser drilling or other precision machining techniques. The specific manufacturing process depends on the material of the annular retaining member 32 and the required accuracy, and can also be set according to user needs, which will not be elaborated here.

[0039] In some examples, the inner surface of the through hole may be polished or coated. The specific method of polishing or coating can be set according to needs, and can also refer to related technologies. It is not elaborated here. Polishing or coating the inner surface of the through hole can reduce the resistance to gas flow and prevent wear or corrosion inside the through hole during the polishing process.

[0040] Reference Figure 5 When the plurality of through holes in the vent 321 are arranged uniformly in an array along the circumferential direction of the annular retainer 32, the annular retainer 32 may present a mesh structure. The mesh structure enables the annular retainer 32 to ensure its mechanical strength while allowing gas to enter the annular retainer 32 from the outer surface of the annular retainer 32 through the through holes.

[0041] Reference Figure 6 The vent 321 may also be a groove, which is an elongated channel made on the annular retainer 32 for guiding gas from the external environment of the polishing head into its internal space.

[0042] The groove can be designed to be an elongated shape to optimize gas flow and reduce the impact on the structural strength of the annular retainer 32. The width and depth of the groove need to be precisely designed according to the gas flow requirements and the material properties of the annular retainer 32. The specific design can be customized based on the requirements and will not be described in detail here.

[0043] The cross-section of the groove can be a triangle, trapezoid, rectangle, etc., or an arc shape or some irregular shape, as long as the gas can be introduced from the outside of the annular retaining member 32 into the inside of the annular retaining member. The specific shape design will not be repeated here.

[0044] In some examples, the groove generally starts from the end surface of the annular holder 32 and extends inward to the middle portion of the holder, so that the wafer 4 can receive gas during the polishing process.

[0045] Optionally, the groove extends from the end surface of the annular retainer 32 away from the polishing head body to the middle of the annular retainer 32. This ensures that the end of the annular retainer 32 away from the polishing head body, that is, the end close to the polishing pad 5, is complete, which can better limit the position of the wafer 4.

[0046] In some examples, the groove body can extend radially along the annular retaining member 32 so that the airflow can enter the interior of the annular retaining member 32 through the shortest path to reduce the pressure difference between the front side of the wafer 4 and the back side of the wafer 4 during the CMP process.

[0047] The groove can be formed by a variety of manufacturing processes, including machining, chemical etching or laser cutting, etc. The specific process selected depends on the material properties of the annular retainer 32, the size requirements of the groove and the cost-effectiveness, and can also be customized according to user needs, which will not be described in detail here.

[0048] The inner surface of the groove may need to be polished or coated. This surface treatment helps reduce resistance to gas flow and protects the groove from corrosion.

[0049] In some examples, the vent 321 may include both a groove and a through hole. The groove may extend along the end surface of the annular retainer 32 away from the adsorption film 31 toward the inside of the annular retainer 32 , and the through hole is provided on the side of the annular retainer 32 close to the adsorption film 31 .

[0050] In some examples, the grooves and the through holes may be evenly and alternately arranged in the axial direction of the annular retaining member 32 , so that the annular retaining member 32 can evenly convey airflow to the interior of the annular retaining member 32 through the grooves and the through holes.

[0051] In some examples, the polishing head includes an adsorption film 31, which is used to fix one end face of the annular retainer 32 to form a connection between the polishing head and the wafer 4. One end face of the annular retainer 32 is fixed to the adsorption film 31 in a specific manner, and this fixation can be permanent or removable to facilitate maintenance and replacement of the polishing head. The adsorption film 31 can be made of a variety of materials, such as polyester, polypropylene or other polymer materials, which have good adsorption properties and chemical stability.

[0052] In some examples, the side of the annular retainer 32 away from the adsorption mold 31 can be made of elastic material. This design makes this side flexible, and the elastic material can absorb the impact and vibration during the polishing process, reduce mechanical damage to the wafer 4, and improve the yield of the wafer 4. The elastic material can distribute the polishing pressure more evenly, so the polishing uniformity of the surface of the wafer 4 can be improved and polishing defects can be reduced.

[0053] In some examples, the material of the annular retainer 32 can be selected from polyurethane, silicone rubber or other high-performance elastic materials. These materials have good elasticity and durability and can maintain performance during long-term polishing. The elastic material can be combined with the rigid part of the annular retainer 32 through processes such as injection molding, vulcanization or hot pressing to ensure the stability and durability of the overall structure. Parameters such as the thickness, hardness and elastic modulus of the elastic part need to be accurately designed according to the requirements of the actual polishing process to ensure the best polishing effect, which will not be described in detail in this example implementation.

[0054] In some examples, the annular retainer 32 may be fixed by a retractable mechanism so that the annular retainer 32 can be moved or adjusted within a certain range to accommodate wafers 4 of different thicknesses. The retractable design enables the polishing head to adapt to wafers 4 of different thicknesses, thereby improving the versatility and flexibility of the polishing head.

[0055] Specifically, the retractable fixation can be achieved through a variety of mechanisms, such as using springs, elastic materials, telescopic arms, or adjustable buckles, etc. The adjustment range of the annular retainer 32 can be determined to ensure that the thickness range of the required polished wafer 4 can be covered. The specific adjustment logic can be customized based on user needs and will not be described in detail in this example implementation.

[0056] In some examples, a locking mechanism may be provided to fix the annular retainer 32 after the annular retainer 32 is adjusted to a suitable position, so as to ensure that the annular retainer 32 is not displaced due to vibration or pressure changes during the polishing process.

[0057] In some examples, the thickness of the annular retaining member 32 can be set to 0.70 mm ~ 0.85 mm, wherein the thickness of the annular retaining member 32 is the distance between the two end faces of the annular retaining member 32 in the axial direction, which can ensure the structural strength of the annular retaining member 32, so that the annular retaining member 32 can withstand high pressure and friction, and better limit the wafer 4.

[0058] The polishing head in the disclosed embodiment allows gas to enter between the wafer 4 and the polishing pad 5 by providing a vent 321 on the annular retainer 32, effectively reducing the pressure difference caused by the surface tension of water, thereby reducing the risk of the wafer 4 falling and breaking when the polishing head is lifted. Multiple through holes are evenly distributed along the circumference of the annular retainer 32 to ensure that the entire wafer 4 area can evenly receive gas, avoid uneven pressure during the polishing process, and improve the uniformity of polishing. The inner surface polishing or coating treatment of the through hole reduces the resistance to gas flow and prevents wear or corrosion during the polishing process, thereby improving the durability and maintenance cycle of the polishing head.

[0059] Furthermore, the present disclosure also provides a polishing system, including a polishing head and a polishing pad 5 , wherein the polishing pad 5 is used to cooperate with the polishing head to polish the wafer 4 .

[0060] Optionally, the polishing pad 5 can be a non-grooved polishing pad 5, the front side of which is designed with ultra-dense holes of micron size, and the overall surface is relatively flat. This can effectively prevent the grooves from significantly deteriorating the nano-morphology of the silicon wafer surface during the polishing process. During the CMP process using the non-grooved polishing pad 5, the material removal rate increases linearly with the increase of pressure, and the removal efficiency is easy to control. Compared with the polishing pad 5 with grooves, the non-grooved polishing pad 5 shows a greater material removal rate under the same conditions.

[0061] In the above embodiments, the description of each embodiment has its own emphasis. For the part not described in detail in a certain embodiment, please refer to the relevant description of other embodiments. The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the inventions claimed herein. The present disclosure is intended to cover any variations, uses or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not claimed in the present disclosure.

[0063] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A polishing head, characterized in that: include: An annular retaining member, used for limiting the position of the wafer in the radial direction of the wafer when the polishing head carries the wafer; The vent is arranged on the annular holder so that when the wafer holder is in contact with the polishing pad, gas can enter the annular holder through the vent.

2. The polishing head according to claim 1, characterized in that: The venting portion comprises: At least one through hole extends along a radial direction of the wafer.

3. The polishing head according to claim 2, characterized in that: There are multiple through holes, and the multiple through holes are evenly arranged in an array along the circumferential direction of the annular retaining member.

4. The polishing head according to claim 1, characterized in that: The venting portion comprises: At least one groove extends along one end surface of the annular retaining member toward the middle of the annular retaining member.

5. The polishing head according to claim 4, characterized in that: The groove extends from the end surface of the annular holder away from the polishing head body to the middle of the annular holder.

6. The polishing head according to claim 1, characterized in that: The polishing head also includes: The adsorption film is provided, and one end surface of the annular retaining member is fixed to the adsorption film.

7. The polishing head according to claim 6, characterized in that: The side of the annular retaining member away from the adsorption pad is made of elastic material.

8. The polishing head according to claim 6, characterized in that: The annular retaining member is telescopically fixed to the adsorption film, so that the annular retaining member can limit the position of wafers with different thicknesses.

9. The polishing head according to claim 1, characterized in that: The material of the annular retainer includes at least one of glass fiber, polyurethane, ceramic, plastic and metal.

10. A polishing system, characterized in that: include: The polishing head according to any one of claims 1 to 9; The polishing pad is used to cooperate with the polishing head to polish the wafer.

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