Magnetic force applying bearing head for magnetic field assisted photochemical mechanical polishing

Abstract

The invention relates to a magnetic force applying carrier head for magnetic field assisted photochemical mechanical polishing. A one-way strong magnetic field is provided by embedding magnets in a Halbach array, and a magnetic speed change gear is utilized, so that the problems that a local magnetic field is difficult to apply and the relative speed of a workpiece magnetic field is difficult to increase in a traditional chemical mechanical polishing device are solved. The device comprises an inner magnetic module, an outer magnetic module, a center shaft rotating module unit and the like. The wafer is fixed on the surface of the bearing head through the conductive adhesive, the outer magnetic module is driven to rotate, and the outer magnetic module drives the inner magnetic module for manufacturing a one-way strong magnetic field to rotate in the opposite direction through the magnetic variable gear, so that the speed of cutting magnetic induction lines is increased, and the inhibition effect of the magnetic field on electron-hole pair recombination is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor wafer polishing, and in particular to a magnetic force application bearing head for magnetic field assisted photochemical mechanical polishing. Background Art

[0002] Third-generation semiconductor materials possess excellent physical and electrical properties. Compared to traditional materials such as silicon and potassium arsenide, third-generation semiconductors excel in high-temperature, high-frequency, high-power, and high-efficiency applications. With the rise of emerging industries such as 5G, smart grids, electric vehicles, and renewable energy, third-generation semiconductors are finding increasingly widespread application. However, due to their high hardness and chemical inertness, conventional chemical mechanical polishing (CMP) has an extremely low material removal rate.

[0003] Therefore, people have studied photochemical mechanical polishing technology, which uses ultraviolet light to excite the semiconductor surface to produce electron-hole pairs, and then uses the strong oxidizing property of the holes to convert the semiconductor surface into a softer oxide layer to improve the material removal rate. However, the recombination period of electron-hole pairs is extremely short, and without interference, the hole utilization rate is very low. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a magnetic force application carrier head for magnetic field assisted photochemical mechanical polishing of semiconductor wafers.

[0005] The technical means adopted in the present invention are as follows: A magnetic force application bearing head for magnetic field assisted photochemical mechanical polishing, comprising a magnetic application central axis rotation unit, a wafer bearing unit and a fixed adapter unit; the fixed adapter unit is mounted on a workbench; the magnetic application central axis rotation unit is connected to a central ring flange via an inner central ring oblique ball bearing; the wafer bearing unit is connected to the central ring flange via a central and outer ring oblique ball bearing, and is driven by a motor to perform rotational motion around the main axis; the wafer bearing unit is used to carry the wafer, and is provided with an outer ring magnet that can rotate around the axis, constituting the driving side of a magnetic speed change gear; the magnetic application central axis rotation unit is provided with an array magnet and an inner ring magnet for providing a unidirectional strong magnetic field along the main axis, and the inner ring magnet constitutes the driven side of the magnetic speed change gear.

[0006] Furthermore, the magnetically applied central axis rotation unit includes an inner ring magnetic disk, an inner ring gear magnet fixing ring and an inner ring magnet; the upper part of the inner ring magnetic disk provides a unidirectional strong magnetic field along the main axis according to the Halbach array embedded magnet, and the middle part of the inner ring magnetic disk is embedded with n inner ring magnets, forming the driven side of the magnetic speed change gear; the inner ring gear magnet fixing ring is installed to the bottom of the inner ring magnet.

[0007] Furthermore, the chip carrying unit includes a carrying head, an outer ring flange and an outer ring magnet; the outer ring flange is connected to the middle ring flange through the middle and outer ring oblique ball bearings, and the bottom is installed on the turntable, rotating around the main axis; the carrying head is installed on the outer ring flange, and N outer ring magnets are embedded inside, forming the driving side of the magnetic speed change gear, so that the reverse transmission ratio of the inner and outer rings is N:n, and the chip is fixed on the top of the carrying head with conductive glue.

[0008] Furthermore, the fixed adapter unit includes a middle ring iron, a middle ring flange, an inner middle ring oblique ball bearing and a middle and outer ring oblique ball bearing; the inner middle ring oblique ball bearing and the middle and outer ring oblique ball bearing are installed on the middle ring flange; the middle ring flange is fixed on the workbench and embedded with the middle ring iron to form the middle structure of the magnetic speed change gear.

[0009] Compared with the existing technology, the present invention has the following advantages: the present invention proposes to use the magnetic field to generate Lorentz force, use the embedded magnets in the Halbach array to generate a unidirectional strong magnetic field, use the magnetic speed change gear to increase the relative speed between the magnetic field and the chip, increase the magnitude of the Lorentz force exerted on electrons and holes, inhibit the recombination of electron-hole pairs, obtain a higher hole utilization rate, and improve the polishing material removal rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0011] Figure 1 A schematic diagram of the operation of a magnetic force application carrier head for magnetic field-assisted photochemical mechanical polishing according to the present invention; Figure 2 It is an overall schematic diagram of a magnetic force application carrier head for magnetic field assisted photochemical mechanical polishing of the present invention; Figure 3 The figure is a cross-sectional schematic diagram of a magnetic force application carrier head for magnetic field assisted photochemical mechanical polishing according to the present invention.

[0012] In the figure: 1. Carrying head; 2. Outer ring magnet; 3. Outer ring flange; 4. Middle ring iron; 5. Middle ring flange; 6. Inner ring magnetic disk; 7. Middle and outer ring oblique ball bearings; 8. Inner ring magnet; 9. Inner ring gear magnet fixing ring; 10. Inner middle ring oblique ball bearing; 11. Embedded magnet; 12. UV lamp; 13. Polishing liquid inlet pipe; 14. Polishing disk; 15. Wafer; 16. Workbench; 17. Spindle. DETAILED DESCRIPTION

[0013] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0014] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0015] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0016] Unless otherwise specified, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0017] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0018] For ease of description, spatially relative terms such as "above," "above," "on the upper surface of," and "above" may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "on top of" another device or structure would then be positioned as "below" or "below" the other device or structure. Thus, the exemplary term "above" may include both the orientations of "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used herein should be interpreted accordingly.

[0019] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0020] like Figure 1 、 Figure 2 、 Figure 3 As shown, an embodiment of the present invention discloses a magnetic force application carrying head for magnetic field assisted photochemical mechanical polishing, comprising a magnetic force application central axis rotation unit, a chip carrying unit and a fixed adapter unit; the fixed adapter unit is installed on a workbench 16; the magnetic force application central axis rotation unit is connected to the central ring flange 5 through an inner central ring oblique ball bearing 10; the chip carrying unit is connected to the central ring flange 5 through a central and outer ring oblique ball bearing 7, and is driven by a motor to perform rotational motion around the main axis 18, the chip carrying unit is used to carry the chip, and is provided with an outer ring magnet that can rotate around the axis, constituting the driving side of the magnetic speed change gear, the magnetic force application central axis rotation unit is provided with an array magnet and an inner ring magnet for providing a unidirectional strong magnetic field along the main axis, and the inner ring magnet constitutes the driven side of the magnetic speed change gear.

[0021] Specifically, the motor (hollow turntable) drives the wafer carrier unit to rotate, and the wafer carrier unit uses a magnetic speed-changing gear to drive the magnetic application central axis rotating unit that creates a unidirectional strong magnetic field to rotate in the opposite direction, thereby increasing the speed of cutting the magnetic flux lines and enhancing the magnetic field's inhibitory effect on electron-hole pair recombination.

[0022] The magnetically applied central axis rotation unit includes an inner ring magnetic disk 6, an inner ring gear magnet fixing ring 9, and an inner ring magnet 8. A slot is provided on the upper portion of the inner ring magnetic disk 6 for mounting an embedded magnet 11. The embedded magnet 11 provides a unidirectional strong magnetic field upward along the main axis according to the Halbach array. N inner ring magnets 8 are embedded in the middle of the inner ring magnetic disk, forming the driven side of the magnetic speed change gear. Each inner ring magnet 8 is equipped with an inner ring gear magnet fixing ring 9. Specifically, the inner ring gear magnet fixing ring 9 is mounted to the bottom of the inner ring magnet 8 to secure the inner ring magnet 8 to the inner ring magnetic disk 6. The inner ring magnetic disk 6 is rigidly connected to the inner ring of the inner center ring inclined ball bearing 10.

[0023] The wafer carrying unit includes a carrying head 1, an outer ring flange 3 and an outer ring magnet 2; the outer ring flange 3 is connected to the middle ring flange 5 through the middle and outer ring inclined ball bearings 7, and the bottom of the outer ring flange 3 is installed on the turntable and rotates around the main axis; the outer ring flange 3 is connected to the following middle ring flange 5, and the wafer carrying unit is driven to rotate by a motor, and the motor is connected to the outer ring flange 3; the outer ring flange 3 is active, driving the inner magnetic part to rotate, and the inner magnetic part is driven.

[0024] The carrier head 1 is mounted on the outer ring flange 3. N outer ring magnets 2 are embedded within the carrier head 1, forming the drive side of the magnetic speed change gear. This creates an N:n reverse transmission ratio between the inner and outer rings, meaning the directions of rotation are opposite, resulting in an N:n speed ratio. A groove for mounting a wafer 15 is provided above the carrier head 1. During use, the wafer is secured with conductive adhesive. The outer ring flange 3 acts as a fixing ring, allowing the outer ring magnets 2 to be directly installed therein. A vertical through-hole is provided on the outer ring flange 3, serving as a connection to the rotating portion of the hollow turntable.

[0025] The fixed adapter unit includes a middle ring iron 4, a middle ring flange 5, an inner middle ring oblique ball bearing 10 and a middle and outer ring oblique ball bearing 7; the inner middle ring oblique ball bearing 10 and the middle and outer ring oblique ball bearing 7 are installed on the middle ring flange 5; the middle ring flange 5 is fixed on the workbench and embedded with the middle ring iron 4 to form the middle structure of the magnetic speed change gear.

[0026] The magnetic speed change gear comprises an outer ring magnet 2 , a middle ring iron 4 and an inner ring magnet 8 .

[0027] The assembly process of the magnetic force application bearing head for magnetic field-assisted photochemical mechanical polishing in the present invention is as follows: first, the outer ring flange 3 is installed on the turntable; then, the middle and outer ring oblique ball bearings 7, the middle ring flange 5 embedded with the middle ring iron 4, the inner middle ring oblique ball bearing 10 and the inner ring magnetic disk 6 embedded with the inner ring magnet 8 are installed in sequence from the outside to the inside, wherein the middle ring flange 5 is fixed to the workbench; finally, the bearing head 1 embedded with the outer ring magnet 2 is installed on the outer ring flange 3.

[0028] The magnetic force application bearing head for magnetic field assisted photochemical mechanical polishing provided by the present invention includes a magnetic force application central axis rotation unit, a chip bearing unit and a fixed adapter unit; the fixed adapter unit is installed on a workbench; the magnetic force application central axis rotation unit is connected to the central ring flange 5 through an inner central ring oblique ball bearing 10; the chip bearing unit is connected to the central ring flange 5 through an inner and outer ring oblique ball bearing 7, and is driven by a motor to rotate around the main axis. The chip bearing unit uses a magnetic speed change gear to drive the magnetic force application central axis rotation unit that produces a unidirectional strong magnetic field to rotate in the opposite direction, thereby increasing the speed of cutting magnetic lines of force and enhancing the inhibitory effect of the magnetic field on the recombination of electron-hole pairs.

[0029] The wafer carrier unit includes a carrier head 1, an outer ring flange 3, and an outer ring magnet 2. The outer ring flange 3 is connected to the middle ring flange 5 via the middle and outer ring oblique ball bearings 7. The bottom is mounted on the turntable and rotates around the main axis. The carrier head 1 is mounted on the outer ring flange 3. In this embodiment, 20 outer ring magnets 2 with dimensions of 32mm x 20mm x 20mm are embedded inside, forming the driving side of the magnetic speed change gear, so that the reverse transmission ratio of the inner and outer rings is 2:1. The wafer is fixed on the top of the carrier head 1 with conductive glue. The fixed adapter unit includes a middle ring iron 4, a middle ring flange 5, an inner middle ring oblique ball bearing 10 and a middle and outer ring oblique ball bearing 7; the inner middle ring oblique ball bearing 10 and the middle and outer ring oblique ball bearing 7 are installed on the middle ring flange 5; the middle ring flange 5 is fixed on the workbench and embedded with the middle ring iron 4 to form the middle structure of the magnetic speed change gear.

[0030] The magnetically applied central axis rotation unit includes an inner ring magnetic disk 6, an inner ring gear magnet fixing ring 9 and an inner ring magnet 8; the upper part of the inner ring magnetic disk 6 has embedded magnets according to the Halbach array to enhance the magnetic field strength in the unit direction. In this embodiment, 10 inner ring magnets 8 are embedded in the middle part, with a size of 30mmx20mmx12mm, constituting the driven side of the magnetic speed change gear; the inner ring gear magnet fixing ring 9 is installed to the bottom of the inner ring magnet 8; the inner ring magnet 8, the middle ring iron 4 and the outer ring magnet 2 are on the same horizontal plane; the middle ring iron can optimize the magnetic field distribution, while enhancing torque transmission, improving the magnetic field utilization and transmission efficiency, and improving the carrying capacity of the transmission system.

[0031] In the actual processing process, S1, install the carrier head on the workbench 16; S2. Magnetic field adjustment method: During the processing of this method, ultraviolet light with a wavelength of 365nm and adjustable light intensity is directly irradiated onto the surface of the processed wafer through a polishing disk and a polishing liquid with good light transmittance. Electrons in the valence band are excited by the light energy and jump to the conduction band, leaving positively charged holes with strong oxidizing properties in the valence band. In this method, an adjustable intensity magnetic field is applied to the wafer processing area. The electrons and holes rotate with the outer ring flange to generate a speed that cuts the magnetic flux lines. Due to the opposite charges, the two are subjected to Lorentz forces in opposite directions. The magnitude of this Lorentz force is adjusted by selecting magnets of different sizes and the ratio of the number of outer and inner ring magnets, the polishing disk rotation speed or different magnetic induction intensities during the processing. Under the action of the Lorentz force, the electrons and holes move in opposite directions, thereby suppressing their recombination. The wafer surface is oxidized by the holes with strong oxidizing properties to form an oxide layer with a relatively soft hardness.

[0032] S3. A polishing unit integrating an ultraviolet lamp 12, a polishing liquid input pipe 13 and a polishing disk 14 is arranged on the top to realize simultaneous application of light field and magnetic field in chemical mechanical polishing.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetic force application carrier head for magnetic field assisted photochemical mechanical polishing, characterized in that: It includes a magnetically applied central axis rotation unit, a wafer carrying unit and a fixed adapter unit; the fixed adapter unit is installed on a workbench; the magnetically applied central axis rotation unit is connected to the central ring flange through an inner central ring oblique ball bearing; the wafer carrying unit is connected to the central ring flange through a central and outer ring oblique ball bearing, and is driven by a motor to rotate around the main axis. The wafer carrying unit is used to carry the wafer, and is provided with an outer ring magnet that can rotate around the axis, constituting the driving side of the magnetic speed change gear. The magnetically applied central axis rotation unit is provided with an array magnet and an inner ring magnet for providing a unidirectional strong magnetic field along the main axis, and the inner ring magnet constitutes the driven side of the magnetic speed change gear.

2. The magnetic force application carrier head for magnetic field assisted photochemical mechanical polishing according to claim 1, characterized in that: The magnetically applied central axis rotation unit includes an inner ring magnetic disk, an inner ring gear magnet fixing ring and an inner ring magnet; the upper part of the inner ring magnetic disk provides a unidirectional strong magnetic field along the main axis according to the Halbach array embedded magnet, and the middle part of the inner ring magnetic disk is embedded with n inner ring magnets, forming the driven side of the magnetic speed change gear; the inner ring gear magnet fixing ring is installed to the bottom of the inner ring magnet.

3. The magnetic force application carrier head for magnetic field assisted photochemical mechanical polishing according to claim 1, characterized in that: The wafer carrying unit includes a carrying head, an outer ring flange and an outer ring magnet; the outer ring flange is connected to the middle ring flange through the middle and outer ring oblique ball bearings, and the bottom is installed on the turntable and rotates around the main axis; the carrying head is installed on the outer ring flange, and N outer ring magnets are embedded inside, forming the driving side of the magnetic speed change gear, and the wafer is fixed on the top of the carrying head with conductive glue.

4. The magnetic force application bearing head for magnetic field assisted photochemical mechanical polishing according to claim 1, wherein the number of the inner ring magnets is n, the number of the outer ring magnets is N, and the reverse transmission speed ratio of the inner and outer rings is N:n.

5. The magnetic force application carrier head for magnetic field assisted photochemical mechanical polishing according to claim 1, characterized in that: The fixed adapter unit includes a middle ring iron, a middle ring flange, an inner middle ring oblique ball bearing and a middle and outer ring oblique ball bearing; the inner middle ring oblique ball bearing and the middle and outer ring oblique ball bearing are installed on the middle ring flange; the middle ring flange is fixed on the workbench and embedded with the middle ring iron to form the middle structure of the magnetic speed change gear.

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