Elastic film, carrier head, chemical mechanical polishing apparatus and method

Abstract

The application provides an elastic film, a carrier head, a chemical mechanical polishing device and a method. The elastic film comprises: a bottom plate part configured to contact a wafer downward; a peripheral wall extending upward along the edge of the bottom plate part; a partition rib located on the inner side of the peripheral wall, comprising a horizontal rib and a vertical rib, the vertical rib extending upward along the bottom plate part, the end of the vertical rib extending horizontally to form the horizontal rib, and the vertical rib having a negative Poisson's ratio structure; and the partition rib and the peripheral wall divide the elastic film into multiple chambers. The elastic film of the application can reduce or even eliminate the three-zone coupling during polishing of the wafer, improve the pressure fluctuation at the partition rib, improve the polishing precision, and ultimately improve the wafer yield in advanced processes.

Description

Technical Field

[0001] This invention belongs to the field of chemical mechanical polishing technology and is used for processing semiconductor chips. Specifically, it relates to an elastic membrane, a support head, chemical mechanical polishing equipment, and a method. Background Technology

[0002] Wafer manufacturing is a crucial link in the development of the ultra-large-scale integrated circuit (IC) industry. As Moore's Law continues to shrink, the feature size of integrated circuits continues to approach its theoretical limit, leading to increasingly stringent requirements for wafer surface quality. Consequently, the control of defect size and quantity in the wafer manufacturing process is becoming increasingly rigorous. Chemical mechanical polishing (CMP) is a global surface planarization technique used in semiconductor manufacturing to reduce the impact of wafer thickness variations and surface morphology. Because CMP can precisely and uniformly planarize wafers to the required thickness and flatness, it has become the most widely used surface planarization technique in semiconductor manufacturing.

[0003] Chemical mechanical polishing (CMP) involves pressing a wafer against a polishing pad using a support head. Polishing is achieved through the relative motion between the wafer and the pad, aided by abrasive particles in the polishing slurry. The support head incorporates a flexible air film (i.e., an elastic membrane), separating the traditional airbag into multiple independent pressure chambers. This is achieved through isolation fascias, allowing for zoned pressure control. Air films for 12-inch wafer processing already have 5 or 7 zones. Responding to the increasing demand from customers for effective control of removal rates at the wafer center and edge, future products will inevitably move towards more zones.

[0004] The increased number of partitions enhances the control capability of the bearing head, but the addition of partitions can lead to the coupling of pressure between the three partitions (i.e., "three-zone coupling") and cause the pressure transmission near the rib to "go out of control", which directly affects the processing quality of the wafer surface and ultimately leads to a decrease in chip yield. Summary of the Invention

[0005] In view of this, the present invention provides an elastic membrane, a bearing head, a chemical mechanical polishing apparatus and method, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0006] A first aspect of the present invention provides an elastic membrane for chemical mechanical polishing, comprising: The base plate is used for downward contact with the wafer; The perimeter wall extends upwards along the edge of the base plate; The dividing ribs are located on the inner side of the peripheral wall and include horizontal ribs and vertical ribs. The vertical ribs extend upward along the bottom plate and the ends of the vertical ribs extend horizontally to form horizontal ribs. The vertical ribs have a negative Poisson's ratio structure. The ribs and peripheral walls divide the elastic membrane into multiple chambers.

[0007] Optionally, the Poisson's ratio of the vertical rib is -0.5 to -0.2, the thickness of the vertical rib is 1 to 1.3 mm when no pressure is applied, and the thickness of the vertical rib is 0.4 to 0.6 mm when pressure is applied at 2 to 4 pounds per square inch.

[0008] Optionally, the horizontal ribs have a negative Poisson's ratio structure.

[0009] Optionally, the negative Poisson's ratio structure is a porous structure with a concave polygonal shape.

[0010] Optionally, the elastic membrane is made of shape memory polymer through 3D printing.

[0011] Optionally, the shape memory polymer is incorporated with conductive fibers and / or conductive fillers to enable the elastic membrane to be used for electrochemical mechanical polishing.

[0012] Optionally, the peripheral wall includes: The upright portion extends upward along the edge of the base plate portion; The first extension extends from the end of the upright portion toward the center of the elastic membrane; The second extension is located between the first extension and the base plate, and extends along the inner side of the upright portion toward the center of the elastic membrane. The first extension, the second extension, and the upright portion form the first chamber; The second extension, the upright part, and the outermost partition rib form the second chamber; The ends of the horizontal rib, the first extension, and the second extension each expand to form a fixing part.

[0013] A second aspect of the present invention provides a support head for chemical mechanical polishing, comprising: a base, a retaining ring, a pressure ring, and the elastic membrane described in the first aspect; The pressure ring fixes the elastic membrane to the base below through a fixing part, which is formed by the expansion of the ends of the partition rib and the peripheral wall. A retaining ring is positioned below the base, surrounding the elastic membrane. A fluid channel is configured in the base, and an external air source is connected to the chamber of the elastic membrane through the fluid channel to adjust the pressure of the chamber; The number of chambers is no less than ten.

[0014] A third aspect of the present invention provides a chemical mechanical polishing apparatus, comprising: a polishing disc, a polishing pad, a dresser, a liquid supply unit, and the bearing head described in the second aspect.

[0015] Optionally, the carrier head further includes a wafer carrier device; the carrier head interacts with the wafer carrier device via the elastic membrane.

[0016] A fourth aspect of the present invention provides a chemical mechanical polishing method using the chemical mechanical polishing equipment described in the third aspect, comprising: The carrier head is controlled to move to the wafer interaction position, and the chamber is evacuated so that the elastic membrane attracts the wafer; The carrier head is controlled to move above the polishing pad, and the chamber is pressurized to pressurize the chamber and the wafer is pressed against the polishing pad through the elastic membrane; The carrier head and polishing pad are rotated to perform chemical mechanical polishing on the wafer; The carrier head is controlled to move to the wafer interaction position, and the chamber is pressurized, causing the elastic membrane to release the wafer.

[0017] The present invention has the following technical effects: The elastic membrane of the present invention includes separators with a negative Poisson's ratio structure, which can reduce or even eliminate three-zone coupling during wafer polishing and improve pressure fluctuations at the separators, thereby improving polishing accuracy and ultimately improving wafer yield in advanced processes, especially in polishing heads with more than ten zones. The bearing head, chemical mechanical polishing equipment, and chemical mechanical polishing method of the present invention can also ensure the stability of the polishing and interaction processes, reduce the risk of debris, and improve production efficiency and quality. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0019] Figure 1 This is a schematic diagram of a chemical mechanical polishing (CMP) device.

[0020] Figure 2 This is a cross-sectional schematic diagram of the bearing head.

[0021] Figure 3 This is a schematic diagram of the structure of an elastic membrane.

[0022] Figure 4 This is a schematic diagram illustrating the different forms of the elastic membrane under negative pressure, no pressure, and positive pressure according to an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram showing the pressure fluctuation of the separator bars of different thicknesses.

[0024] Figure 6 This is a schematic flowchart of the chemical mechanical polishing method according to an embodiment of the present invention.

[0025] Reference numerals: bearing head 10; base 11; retaining ring 12; pressure ring 13; elastic membrane 14; bottom plate 141; peripheral wall 142; upright part 1421; first extension 1422; second extension 1423; partition rib 143; horizontal rib 1431; vertical rib 1432; polishing disc 20; polishing pad 21; dressing device 30; liquid supply part 40. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

[0027] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] In addition, in the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0029] In this invention, chemical mechanical polishing is also called chemical mechanical planarization, and wafer is also called wafer, silicon wafer, substrate, etc., with the same meaning and actual function.

[0030] like Figure 1 As shown, the chemical mechanical polishing equipment includes a support head 10 for holding the wafer and rotating the wafer w, a polishing disk 20 covered with a polishing pad 21, a dresser 30 for dressing the polishing pad 21, and a liquid supply unit 40 for supplying polishing fluid.

[0031] During chemical mechanical polishing (CMP), the support head 10 presses the wafer onto the polishing pad 21 covering the surface of the polishing disk 20. The support head 10 rotates and reciprocates radially along the polishing disk 20, gradually removing surface material from the wafer in contact with the polishing pad 21. Simultaneously, the polishing disk 20 rotates, and the liquid supply unit 40 sprays polishing slurry onto the surface of the polishing pad 21. Under the chemical action of the polishing slurry, the relative movement between the support head 10 and the polishing disk 20 causes the wafer to rub against the polishing pad 21 for polishing. During polishing, a dresser 30 is used to trim and activate the surface morphology of the polishing pad 21. The dresser 30 can remove impurity particles remaining on the surface of the polishing pad 21, such as abrasive particles in the polishing slurry and waste material detached from the wafer surface, and can also smooth out surface deformation of the polishing pad 21 caused by abrasion.

[0032] like Figure 2 As shown, the carrier head 10 includes a base 11, a retaining ring 12, a pressure ring 13, and an elastic membrane 14. The pressure ring 13 fixes the elastic membrane 14 below the base 11, and the retaining ring 12 surrounds the elastic membrane and is disposed below the base 11. That is, the retaining ring 12 and the elastic membrane 14 constitute the lower surface of the carrier head 10, and after the elastic membrane 14 adsorbs the wafer, it keeps the wafer inside the retaining ring 12.

[0033] like Figure 2-3 As shown, the elastic membrane 14 includes a base plate 141, a peripheral wall 142, and a partition rib 143.

[0034] The base plate portion 141 is used for downward contact with the wafer, and the shape of the base plate portion 141 is adapted to the wafer. The shape of the retaining ring 12 is adapted to the base plate portion 141. The peripheral wall 142 extends upward along the edge of the base plate portion 141 to form the outer wall of the elastic film 14. The outer surface of the peripheral wall 142 is opposite to the inner surface of the retaining ring.

[0035] The dividing ribs 143 extend upward along the base plate portion 141 and are located inside the peripheral wall 142 to divide the elastic membrane 14 into multiple chambers. In other words, adjacent dividing ribs 143, as well as the outermost dividing rib 143 and the peripheral wall 142, together with the base plate portion 141, define a central chamber and multiple annular chambers. The central chamber is circular, and the multiple annular chambers are concentric rings with different outer / inner diameters.

[0036] The ends of the separating ribs 143 and the peripheral wall 142 are fixed to the base 11 by pressure rings 13. A fluid channel (not shown) is configured in the base 11, and an external air source communicates with each chamber through the fluid channel to independently adjust the pressure of the corresponding chamber. When the external air source evacuates the chamber, the bottom plate 141 recesses inward to create negative pressure, allowing the elastic membrane to adhere to the wafer. When the external air source pressurizes the chamber, the bottom plate 141 bulges outward to apply positive pressure, thereby providing the working pressure required to remove the wafer surface.

[0037] The number of chambers corresponds to the number of partitions. The pressure of each chamber can be controlled independently, allowing different surface removal rates to be achieved by controlling the pressure of each partition on the wafer surface, thereby improving the control accuracy of wafer surface processing quality.

[0038] The pressure between the zones will interact and couple through the flexible partition ribs. The width of the area where the coupling pressure acts is called the coupling width. When the number of zones is small, the effective width of the chamber is large. The shape of the partition rib 143 will not cause the effective width of the chamber to be smaller than the coupling width. Thus, the entire elastic membrane only has pressure coupling between adjacent zones. This is called "two-zone coupling". "Two-zone coupling" does not cause the pressure transmission near the partition rib to "go out of control".

[0039] To meet the demands of advanced manufacturing processes for wafer surface quality, and to further enhance the controllability of the bearing head, thereby increasing the partitioning of the elastic membrane, the effective width of the chamber (i.e., the chamber width excluding the thickness of the separator ribs) decreases continuously with the increase in the number of partitions. When the effective width of the chamber is less than the coupling width, the separator ribs will be affected by three partitions simultaneously, which is known as "three-zone coupling." Experiments show that regardless of the rib shape, when the elastic membrane design has at least ten partitions, the effective coupling width is approximately 20 mm. The minimum effective width of the chamber must be limited to greater than 18 mm to avoid "three-zone coupling" and thus prevent the pressure transmission near the separator ribs from becoming "uncontrolled."

[0040] However, a 12-inch wafer has a radius of 150mm. Taking 10 zones as an example, the radius of the edge zones (Zone1~Zone3) is reserved at 15-20mm, and the remaining zones are divided radially at 130-135mm. In addition, the thickness of each partition rib 143 is usually greater than 1mm. The effective width of some chambers will inevitably be less than the minimum critical width required to avoid "three-zone coupling" (e.g., 18mm). This will cause the pressure transmission near the corresponding partition rib to "run out of control", which will then form defects such as "dish" or "bump" in the corresponding area on the wafer surface, affecting the wafer surface processing quality and ultimately reducing the chip yield.

[0041] Furthermore, as the number of partitions increases, the length of the separator ribs will also shorten due to space constraints, resulting in insufficient extension of the separator ribs and a risk of wafer drop during wafer handling. Once a wafer drop occurs, it not only affects the production cycle but may also damage the wafer or even cause it to break, leading to a shutdown of the entire production line and causing huge economic losses.

[0042] To address at least one of the aforementioned technical problems, one embodiment of the present invention provides an elastic film for chemical mechanical polishing, which, as shown in the example... Figure 3 The elastic membrane 14 shown has the same external structure, including a base plate 141, a peripheral wall 142, and a partition rib 143.

[0043] The base plate 141 is used to contact the wafer downwards. The shape of the base plate 141 is adapted to the wafer, and the shape of the retaining ring 12 is adapted to the base plate 141. The peripheral wall 142 extends upwards along the edge of the base plate 141 to form the outer wall of the elastic membrane 14. The separating rib 143 extends upwards along the base plate 141 and is located inside the peripheral wall 142 to divide the elastic membrane 14 into multiple chambers. Among them, the multiple chambers are a central chamber that is circular and multiple annular chambers concentric with the central chamber. The annular width of the multiple annular chambers is also the effective width of the chamber.

[0044] The partition rib 143 includes a horizontal rib 1431 and a vertical rib 1432. The vertical rib 1432 extends upward along the base plate portion 141, and the partition rib 143 extends horizontally at the end of the vertical rib 1432 to form a horizontal rib 1431. The respective horizontal ribs 1431 of two adjacent partition ribs 143 extend relative to each other or in opposite directions. The ends of the horizontal ribs 1431 expand to form a fixing portion for fixing the elastic membrane to the base of the polishing head.

[0045] The vertical rib 1432 has a negative Poisson's ratio structure. Materials with a negative Poisson's ratio structure exhibit a negative Poisson's ratio effect, meaning they expand laterally under longitudinal tension and contract laterally under compression. In this invention, by designing specific micro-topological structures (such as concave polygons), the material constituting the vertical rib exhibits a negative Poisson's ratio effect macroscopically. That is, when the vertical rib 1432 is subjected to longitudinal tension, its lateral dimension not only does not contract but expands and thickens; when the vertical rib 1432 is subjected to longitudinal compression, its lateral dimension not only does not expand but contracts and thins.

[0046] Figure 4The images from left to right show the different morphologies of the vertical rib 1432 under negative pressure, no pressure, and positive pressure. The morphology of the vertical rib 1432 when no pressure is applied to the chamber by the external air source is shown in the middle image. The white pattern in the vertical rib 1432 represents the porous structure, resulting in a negative Poisson's ratio characteristic. The morphology of the vertical rib 1432 when the chamber is evacuated by the external air source is shown in the left image. The corresponding arrows indicate the tensile force perpendicular to the extension direction experienced by the vertical rib 1432 due to the applied negative pressure. Compared to the unpressurized morphology, it can be seen that the vertical rib 1432 expands and thickens in the horizontal direction due to the tensile force, and also expands and lengthens in the vertical direction, thus achieving a more substantial extension length. When the external air source pressurizes the chamber, the shape of the vertical rib 1432 is shown in the figure on the right. The corresponding arrows indicate the compressive force perpendicular to the extension direction of the vertical rib 1432 caused by the positive pressure. It can be seen that the vertical rib 1432 shrinks and thins in the horizontal direction due to the compressive force, and also shrinks and shortens in the vertical direction.

[0047] In this embodiment, the separator 143 includes vertical ribs with a negative Poisson's ratio structure. Under pressure, the vertical ribs 1432 horizontally shrink and thin, thereby increasing the effective width of the chamber and achieving the technical effect of reducing or even eliminating three-zone coupling. In the unpressurized state, the separator ribs 143 maintain their original thickness, allowing the elastic membrane to maintain its designed structural strength without affecting processing accuracy and service life. Simultaneously, not changing the normal pressure morphology of the elastic membrane eliminates the need to modify other structures that cooperate with the elastic membrane. Furthermore, under negative pressure, the increased thickness of the vertical ribs accelerates the formation of a local vacuum in the rib area during wafer suction, strengthening the elastic membrane's adhesion to the wafer.

[0048] In addition, the partition bars inevitably cause pressure fluctuations. Figure 5 The pressure fluctuations of the partition ribs with different thicknesses under a uniform pressure of 3.5 pdsi are shown. It can be seen that reducing the thickness of the partition ribs can reduce the amplitude of pressure fluctuations at the partition ribs. In this embodiment, as the vertical rib 1432 contracts and thins horizontally during pressurization, the rigidity of the partition rib 143 decreases significantly, making the pressure transmission of the elastic membrane at the partition ribs more precise and stable. This effectively improves the abnormal pressure response at the partition ribs and also reduces the risk of "runaway" pressure transmission near the partition ribs.

[0049] Optionally, the Poisson's ratio of the vertical rib 1432 is -0.5 to -0.2, the thickness of the vertical rib is 1 to 1.3 mm when uncompressed, and 0.4 to 0.6 mm when compressed at 2 to 4 pounds per square inch (psi).

[0050] Optionally, the horizontal rib 1431 has a negative Poisson's ratio structure, and its shape under no pressure, negative pressure and positive pressure is similar to that of the vertical rib 1432, which will not be described in detail here.

[0051] By incorporating vertical ribs 1432 with a negative Poisson's ratio structure into the separator ribs 1433, which contract bidirectionally under positive pressure, a positive distance between the film gas plate and the retaining ring plate is maintained, preventing the wafer from easily detaching from the retaining ring. When the horizontal ribs 1431 also have a negative Poisson's ratio structure, they expand bidirectionally under negative pressure, working together with the vertical ribs 1432 to sufficiently extend the total length of the separator ribs. This reduces the wafer suction distance while increasing the volume of the vacuum cavity formed by the elastic film plate and the wafer, enhancing the elastic film's adsorption strength on the wafer. This reduces the risk of wafer detachment during wafer suction. Furthermore, the lateral (perpendicular to the extension direction) expansion helps enhance the seal between the fixing part and the pressure ring 13, further reducing the risk of leakage and improving the reliability of vacuum adsorption. The combined effect significantly reduces the risk of wafer fragmentation during chemical mechanical polishing, improving production efficiency and quality.

[0052] Optionally, the porous structure that gives the vertical rib 1432 a negative Poisson ratio can be a concave polygonal structure, a chiral structure, a rigid body structure of rotation, an inverted honeycomb network structure, etc. This negative Poisson ratio characteristic can be achieved by forming corresponding special microstructures on materials such as polyurethane / polyester acrylate / epoxy acrylate / polytetrafluoroethylene. Preferably, the porous structure is a concave polygonal porous structure because the ideal state of the partition rib is only tension and compression, without bending; the concave polygonal porous structure can make the tension and compression effects of the partition rib more pronounced and increase its bending resistance.

[0053] Optionally, the elastic membrane can be made from shape memory polymers via 3D printing. 3D printing allows for automated and rapid structural design of mechanical metamaterials, achieving a printing precision of 10 μm, meeting the requirements for elastic membrane processing accuracy. Furthermore, 3D-printed elastic membrane structures exhibit uniform material properties and stable performance, resolving the issues of poor consistency and overall uniformity found in existing elastic membranes. 3D printing can also program the printed structure according to specific negative Poisson's ratio requirements, enabling the partition ribs 143 to exhibit a required negative Poisson's ratio through a specific structure.

[0054] The concave polygonal porous negative Poisson's ratio structure described in this invention has characteristic dimensions that may be at the micrometer or sub-millimeter level. These are difficult to accurately replicate using traditional molding methods and carry the risk of structural inhomogeneity. By employing 3D printing technology, not only can the preset negative Poisson's ratio structure be manufactured with high precision and consistency, but the structural parameters (such as concave angles and rib widths) can also be flexibly adjusted through programming. This allows for 'digital customization' of the elastic membrane's mechanical properties, optimally adapting to different process requirements (such as wafers of different materials or different polishing fluids). Optionally, the shape memory polymer may incorporate conductive fibers or conductive fillers, or a combination of both, to enable the elastic membrane to be used for electrochemical mechanical polishing. The conductive fibers may comprise conductive or dielectric materials or conductive polymer materials, and may be in the form of fibers or filaments. The shape memory polymer incorporating the conductive fibers is used to fabricate the elastic membrane through 3D printing, thereby achieving uniform and stable conductive properties.

[0055] Furthermore, maintaining a stable current density is crucial during electrochemical mechanical polishing (EMP). The elastic membrane of this invention, with its negative Poisson's ratio structure, thins the separator ribs under pressure. This not only increases the effective width of the chamber and reduces pressure coupling, but also allows for full contact between the substrate and the wafer, and reduces the current distribution on the substrate of the elastic membrane by the separator ribs. This results in a more uniform current distribution and is expected to further improve the planarization effect and wafer surface quality of EMP.

[0056] Optional, such as Figure 3 As shown, the peripheral wall 142 includes an upright portion 1421, a first extension portion 1422, and a second extension portion 1423. The upright portion 1421 extends upward along the edge of the base plate portion, substantially forming the outer wall of the elastic membrane. The first extension portion 1422 extends from the end of the upright portion 1421 toward the center of the elastic membrane. The second extension portion 1423 is located between the first extension portion 1422 and the base plate portion 141, extending along the inner side of the upright portion 1421 toward the center of the elastic membrane. The first extension portion 1422, the second extension portion 1423, and the upright portion 1421 form a first chamber, and the second extension portion 1423, the upright portion 1421, and the outermost partition rib together form a second chamber. The ends of the first extension portion 1422 and the second extension portion 1423 also expand to form fixing portions for fixing the elastic membrane to the base of the polishing head.

[0057] One embodiment of the present invention also provides a carrier head for chemical mechanical polishing, and as such Figure 2 The bearing head 10 shown has the same external structure, including a base 11, a retaining ring 12, a pressure ring 13, and an elastic membrane provided in the embodiments of the present invention.

[0058] like Figure 2 As shown, the pressure ring 13 fixes the elastic membrane to the underside of the base 11 via a fixing part to seal the multiple chambers of the elastic membrane. A retaining ring 12 surrounds the elastic membrane and is disposed below the base 11, holding the wafer inside the retaining ring 12 after the elastic membrane 14 adsorbs the wafer. A fluid channel (not shown) is provided in the base 11, and an external air source is connected to each chamber through the fluid channel to independently adjust the pressure of the corresponding chamber.

[0059] The bearing head of this invention has more than ten partitions, meaning that the number of chambers in the elastic membrane is no less than ten. Because the elastic membrane of this invention includes partition ribs with a negative Poisson's ratio structure, it can reduce or even eliminate three-zone coupling during wafer polishing and improve pressure fluctuations at the partition ribs, thereby improving polishing accuracy and ultimately increasing wafer yield in advanced processes.

[0060] An embodiment of the present invention also provides a chemical mechanical polishing apparatus and a chemical mechanical polishing method, wherein the chemical mechanical polishing apparatus is compatible with, for example, a chemical mechanical polishing device and a chemical mechanical polishing method. Figure 1 The chemical mechanical polishing (CMP) apparatus shown has the same external structure, including a polishing disc 20, a polishing pad 21, a dresser 30, a liquid supply unit 40, and a carrier head provided in the embodiment of the present invention. The CMP method uses the CMP apparatus provided in the embodiment of the present invention to polish wafers.

[0061] Optionally, the chemical mechanical polishing (CMP) equipment also includes a wafer carrier, wherein the carrier head can move between the wafer carrier and the polishing disk, thereby interacting with the wafer carrier via an elastic membrane. The interacted wafers include unpolished wafers and polished wafers, such as... Figure 6 As shown, the complete interaction and polishing process is as follows: Unpolished wafers are placed on a wafer interaction device by an interactive robotic arm; S1: Control the carrier head to move to the aligned wafer interaction device, control the carrier head and / or wafer interaction device to descend and / or rise to be in the wafer interaction position, evacuate the chamber so that the elastic membrane attracts the wafer; S2: After controlling the carrier head and / or wafer interaction device to rise and / or fall to disengage from the wafer interaction position, control the carrier head to move above the polishing pad, pressurize the chamber, and press the wafer against the polishing pad through the elastic membrane; S3: Control the rotation of the carrier head and polishing pad according to the predetermined polishing formula, and control the liquid supply unit to spray polishing liquid onto the surface of the polishing pad to complete the chemical mechanical polishing process of the wafer. S4: After polishing, control the carrier head to move to the wafer interaction position, apply positive pressure to the chamber, so that the elastic membrane releases the wafer, and the released wafer falls on the wafer interaction device; The polished wafers are then transferred away from the wafer interaction device by an interactive robotic arm.

[0062] Optionally, in step S4, the specific steps for applying positive pressure to the chambers are as follows: positive pressure is applied to each chamber sequentially from the edge chambers to the center chamber until all chambers are positively pressured to complete the release of the wafer. Because the separator ribs have a negative Poisson's ratio structure, as the chamber changes from negative pressure to positive pressure, the separator ribs become progressively thinner and shorter from the edge chambers to the center chamber, making it easier for the wafer to separate from the elastic membrane.

[0063] Preferably, when positive pressure is applied to each chamber sequentially from the edge chamber to the center chamber, the positive pressure value on both sides of the separating rib that separates the positive and negative pressure chambers is greater than the negative pressure value after positive pressure is applied to each chamber. Therefore, the resultant force on the separating rib that separates the positive and negative pressure chambers is positive pressure, and the separating rib becomes thinner and shorter, making it easier to open the edges at the separating rib.

[0064] In summary, the chemical mechanical polishing equipment and method of the present invention use a bearing head with more than ten partitions. The elastic membrane of the bearing head includes partition ribs with a negative Poisson's ratio structure, which ensures the stability of the polishing and interaction process, greatly reduces the risk of debris, and improves production efficiency and quality.

[0065] The above embodiments are only used to illustrate the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of the present invention, and the patent protection scope of the embodiments of the present invention should be defined by the claims.

Claims

1. An elastic membrane for chemical mechanical polishing, characterized in that, include: The base plate is used for downward contact with the wafer; The perimeter wall extends upwards along the edge of the base plate; The dividing ribs are located on the inner side of the peripheral wall and include horizontal ribs and vertical ribs. The vertical ribs extend upward along the bottom plate and the ends of the vertical ribs extend horizontally to form horizontal ribs. The vertical ribs have a negative Poisson's ratio structure. The ribs and peripheral walls divide the elastic membrane into multiple chambers.

2. The elastic membrane as described in claim 1, characterized in that, The Poisson's ratio of the vertical rib is -0.5 to -0.2, the thickness of the vertical rib is 1 to 1.3 mm when no pressure is applied, and the thickness of the vertical rib is 0.4 to 0.6 mm when pressure is applied at 2 to 4 pounds per square inch.

3. The elastic membrane as described in claim 1, characterized in that, The horizontal reinforcement has a negative Poisson's ratio structure.

4. The elastic membrane according to any one of claims 1-3, characterized in that, The negative Poisson's ratio structure is a porous structure with an inwardly concave polygonal shape.

5. The elastic membrane as described in claim 4, characterized in that, The elastic membrane is made of shape memory polymer through 3D printing.

6. The elastic membrane as described in claim 5, characterized in that, The shape memory polymer incorporates conductive fibers and / or conductive fillers to enable the elastic membrane to be used for electrochemical mechanical polishing.

7. The elastic membrane as described in claim 6, characterized in that, The peripheral wall includes: The upright portion extends upward along the edge of the base plate portion; The first extension extends from the end of the upright portion toward the center of the elastic membrane; The second extension is located between the first extension and the base plate, and extends along the inner side of the upright portion toward the center of the elastic membrane. The first extension, the second extension, and the upright portion form the first chamber; The second extension, the upright part, and the outermost partition rib form the second chamber; The ends of the horizontal rib, the first extension, and the second extension each expand to form a fixing part.

8. A support head for chemical mechanical polishing, characterized in that, include: The base, retaining ring, pressure ring, and the elastic membrane according to any one of claims 1-7; The pressure ring fixes the elastic membrane to the base below through the fixing part, which is formed by the expansion of the ends of the partition rib and the peripheral wall. A retaining ring is positioned below the base, surrounding the elastic membrane. A fluid channel is configured in the base, and an external air source is connected to the chamber of the elastic membrane through the fluid channel to adjust the pressure of the chamber; The number of chambers is no less than ten.

9. A chemical mechanical polishing device, characterized in that, include: Polishing disc, polishing pad, dressing device, liquid supply unit, and bearing head as described in claim 8.

10. The chemical mechanical polishing apparatus as described in claim 9, characterized in that, It also includes wafer carrier devices; The carrier head interacts with the wafer carrier device via the elastic membrane.

11. A chemical mechanical polishing method, characterized in that, Using the chemical mechanical polishing apparatus as described in any one of claims 9-10, comprising: The carrier head is controlled to move to the wafer interaction position, and the chamber is evacuated so that the elastic membrane attracts the wafer; The carrier head is controlled to move above the polishing pad, and the chamber is pressurized to pressurize the chamber and the wafer is pressed against the polishing pad through the elastic membrane; The carrier head and polishing pad are rotated to perform chemical mechanical polishing on the wafer; The carrier head is controlled to move to the wafer interaction position, and the chamber is pressurized, causing the elastic membrane to release the wafer.

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