Wafer pre-cleaning chamber
The inner and outer permanent magnets cooperate to drive the lifting and rotating of the wafer base, achieving uniform contact between plasma, solving the problem of etching inhomogeneity. At the same time, a static sealing protective cover is used to avoid metal fatigue and pressure leakage and ensure the stability of the vacuum environment.
Patent Information
- Application Number
- CN202411582220.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-02-28
AI Technical Summary
In existing semiconductor vacuum equipment, the movement of plasma during wafer pre-cleaning cannot be controlled, resulting in uneven etching depth of oxides on the wafer surface, affecting product performance and yield. In addition, the long-term lifting and lowering movement of the bellows leads to metal fatigue, which may cause pressure leakage in the vacuum chamber.
The combination of inner and outer permanent magnets is used to drive the lifting and rotating of the wafer base to ensure that the plasma is evenly contacted with the wafer surface and achieve etching uniformity. In addition, metal fatigue and pressure leakage caused by movement are avoided by sealing the static seal with the pre-cleaning chamber.
The uniformity of wafer surface etching is achieved, product performance and yield is improved, and the vacuum state of the vacuum chamber is reliably maintained, avoiding pressure leakage.
Smart Images
Figure CN119542243A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor vacuum equipment pre-cleaning, in particular to a wafer pre-cleaning chamber, which can increase pre-cleaning etching uniformity. Background Art
[0002] In the field of semiconductor production, before physical vapor deposition, wafers usually enter a pre-cleaning chamber. The pre-cleaning chamber uses a radio frequency power supply to ionize the argon gas in the pre-cleaning chamber to generate a high-density plasma. When the plasma moves to the surface of the wafer, it bombards the oxide layer on its surface, thereby achieving the purpose of removing the oxide.
[0003] During the process of gas ionization to generate plasma, the ionized gas molecules are in a random motion state and cannot be controlled to bombard the wafer surface in a targeted manner. Because the plasma concentration inside the cavity may be uneven, it will cause differences in the oxide etching depth on the wafer surface, which in turn affects the performance and yield of the product, so further improvement is needed.
[0004] Moreover, if Figure 1 As shown, the lower end of the wafer base is fixedly connected to the bellows 10, and the inside of the bellows is used to insert the radio frequency (RF) signal line, that is, it is connected to the external atmosphere. The outside of the bellows is not connected to the inside of the vacuum chamber, and the vacuum chamber needs to maintain a vacuum state. The base and the wafer are lifted to the process position by the lifting movement of the bellows 10. After long-term lifting and lowering movement, the bellows will cause metal fatigue of the bellows and easily cause fatigue damage, such as cracks. The cracks will cause the external atmosphere to be connected to the inside of the vacuum chamber, causing the vacuum cavity pressure to leak, thereby destroying the vacuum environment of the vacuum chamber.
[0005] In view of this, there is a need for a wafer base that can uniformly etch a wafer and reliably maintain a vacuum state in a vacuum chamber. Summary of the Invention
[0006]
Technical Issues
[0007] To address the aforementioned issues, the present invention provides a wafer pre-cleaning chamber that utilizes inner and outer permanent magnets to drive the wafer base up and down and rotate, enabling uniform etching. The sealed protective cover and pre-cleaning chamber utilize a static seal to prevent pressure leakage.
[0008]
Technical solution
[0009] A wafer pre-cleaning chamber, comprising:
[0010] a sealing protective cover, one end of which is sealed with the pre-cleaning chamber and the other end of which has an opening;
[0011] A magnetic drive unit, comprising an outer permanent magnet disposed outside the sealing protective cover and an inner permanent magnet disposed within the sealing protective cover, wherein the inner side of the inner permanent magnet is fixedly connected to the wafer base via a hollow rotating shaft;
[0012] The RF signal transmission part includes a conductive slip ring, a brush, and a RF signal introduction rod. The conductive slip ring is inserted into the opening and fixedly connected to the opening. The RF signal introduction rod passes through the conductive slip ring and the inner side of the hollow rotating shaft in sequence and is fixedly connected to the wafer base. The brush is fixedly connected to the lower part of the RF signal introduction rod and is conductively connected to the RF signal introduction rod. The outer side of the brush is slidingly and conductively connected to the inner side of the conductive slip ring.
[0013] Optionally, a shielding cover is fixedly connected to the outer periphery of the wafer base, and the shielding cover surrounds the lower end and side surfaces of the wafer base. The shielding cover is made of conductive material, and a conductive ring is provided on the side wall of the pre-cleaning chamber. The conductive ring is circumferentially arranged on the side wall of the pre-cleaning chamber. A fiber brush bundle is also fixedly connected to the shielding cover, and the fiber brush bundle maintains a conductive connection with the conductive ring.
[0014] Optionally, the conductive ring is embedded in a side wall of the pre-cleaning chamber.
[0015] Optionally, the inner layer permanent magnet and the outer layer permanent magnet are annular, and are formed by stacking a plurality of magnets along the axial and circumferential directions of the hollow rotating shaft, and the magnetic poles of adjacent magnets are opposite.
[0016] Optionally, the outer layer permanent magnets are connected to a rotary drive mechanism, and both the outer layer permanent magnets and the rotary drive mechanism are placed on a lifting platform, and the lifting platform is driven to move up and down by the lifting drive mechanism.
[0017] Optionally, the lifting drive mechanism is a ball screw pair.
[0018] Optionally, the conductive slip ring is insulated from the sealing protective cover.
[0019] Optionally, the wafer base includes a titanium plate and a quartz plate, the titanium plate is embedded in a groove at the upper end of the quartz plate, and the titanium plate and the quartz plate are fixedly connected to the upper end of the RF signal introduction rod by fasteners, and a sunken wafer placement groove is provided on the upper surface of the titanium plate.
[0020] Optionally, there are also lifting pins, which are vertical rods evenly distributed in the circumferential direction, and correspondingly have multiple holes on the wafer base. When the wafer base descends until the lifting pins are inserted into the holes, the wafer base is subject to rotational constraints. When the wafer base rises until the lifting pins come out of the holes, it is not subject to rotational constraints.
[0021] Optionally, the brush is conductively connected to the outer circumference of the radio frequency signal introduction rod.
[0022] Beneficial effects
[0023] This application uses the cooperation of inner and outer permanent magnets to drive the wafer base to rise and fall and rotate, so that the wafer can be in a rotating state after rising to the process position, which can promote the plasma to evenly contact the wafer surface to achieve the purpose of etching uniformity.
[0024] This application uses the cooperation of inner and outer permanent magnets to drive the wafer base to rise and fall and rotate, so that the sealing protection cover and the pre-cleaning chamber can be statically sealed, so there will be no pressure leakage caused by metal fatigue due to movement. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 FIG. 1 is a schematic diagram of a wafer pre-cleaning chamber in the prior art.
[0026] Figure 2 Schematic diagram of a wafer pre-cleaning chamber according to an embodiment of the present application.
[0027] Figure 3 Schematic diagram of the arrangement of the inner and outer permanent magnets in an embodiment of the present application.
[0028] Figure 4 This is a schematic diagram of the connection between the wafer base and the RF signal introduction rod in an embodiment of the present application.
[0029] Figure 5 Schematic diagram of a hole that cooperates with a lifting pin in an embodiment of the present application.
[0030] [Brief Explanation of Reference Numerals]
[0031] 100: Magnetic drive unit 110: Inner permanent magnet
[0032] 120: Outer permanent magnet 130: Rotation drive mechanism
[0033] 200: RF signal transmission unit 210: conductive slip ring
[0034] 220: Brush 230: RF signal introduction rod
[0035] 300: Sealing protection cover 310: Hollow rotating shaft
[0036] 400: Wafer base 410: Titanium plate
[0037] 420: Quartz plate 500: Lifting pin
[0038] 510: hole 600: shielding cover
[0039] 610: Fiber brush bundle 620: Conductive ring DETAILED DESCRIPTION
[0040] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.
[0041] Please refer to Figure 2 The wafer pre-cleaning chamber of this embodiment includes a magnetic drive unit 100, which uses an external permanent magnet to drive the internal permanent magnet to control the lifting and rotation of the base; a radio frequency signal transmission unit 200, which is used to load a bias radio frequency signal on the wafer base 400. The bias radio frequency signal attracts electrons in the plasma and forms a negative bias on the wafer on the wafer base, thereby attracting plasma to bombard the wafer surface, etching away residues on the wafer surface and the bottom of the groove, thereby achieving the purpose of pre-cleaning; a sealed protective cover 300, which accommodates the inner permanent magnet and the radio frequency signal transmission unit 200.
[0042] The magnetic drive unit 100 includes an outer permanent magnet 120 and an inner permanent magnet 110. The inner permanent magnet 110 is located inside the sealing protective cover 300, while the outer permanent magnet 120 is located outside the sealing protective cover 300. Both the inner permanent magnet 110 and the outer permanent magnet 120 can be annular, and the outer permanent magnet 120 surrounds the outer circumference of the inner permanent magnet 110.
[0043] For further information, please refer to Figure 3 , the inner layer permanent magnet 110 and the outer layer permanent magnet 120 can both be formed by stacking multiple magnets in the axial and circumferential directions, and the magnetic poles of adjacent magnets are opposite. For example, in the figure, the inner layer permanent magnet and the outer layer permanent magnet both have 5 layers of permanent magnets in the vertical direction. For each layer of inner layer permanent magnets, multiple magnets are arranged in sequence in the circumferential direction, which can be magnets with a certain curvature. The magnetic poles of adjacent magnets are opposite, thereby forming alternating magnetic poles of N, S, N, S... in the circumferential direction. Similarly, the outer layer permanent magnet of this layer also has multiple magnets arranged in sequence in the circumferential direction, and the magnetic poles of adjacent magnets are opposite, thereby forming alternating magnetic poles of S, N, S, N... in the circumferential direction. Moreover, the magnetic poles of the inner layer permanent magnet of this layer and the outer layer permanent magnet of this layer are arranged in a manner that the N and S poles are opposite to each other. That is to say, at the same circumferential angle in the same layer, if the magnetic pole of the inner permanent magnet is N, then the magnetic pole of the outer permanent magnet is S; if the magnetic pole of the inner permanent magnet is S, then the magnetic pole of the outer permanent magnet is N.
[0044] Similarly, each layer of inner and outer permanent magnets are arranged opposite each other in the above manner, and vertically, the magnetic poles of adjacent layers at the same circumferential angle are also opposite. For example, in the first layer, if one of the outer permanent magnets 120 is an S pole at a certain position, then in the second layer, the magnetic pole of the magnet opposite to the said one is an N pole. In the third layer, the magnetic pole of the magnet opposite to the said one is an S pole. And so on, the arrangement of the inner and outer permanent magnets can be completed. The magnetic poles can be connected as a whole by bonding.
[0045] Based on the principle that opposite magnets attract and like magnets repel, the inner permanent magnets can be synchronized and moved in sync within the magnetic field generated by the outer permanent magnets 120 by controlling the rise and fall and rotation of the outer permanent magnets 120. For example, if the outer permanent magnets 120 rise, the inner permanent magnets rise with them; if the outer permanent magnets fall, the inner permanent magnets fall with them. If the outer permanent magnets 120 rotate clockwise, the inner permanent magnets rotate clockwise as well; if the outer permanent magnets rotate counterclockwise, the inner permanent magnets rotate counterclockwise as well. If the outer permanent magnets 120 stop moving, the inner permanent magnets also stop moving.
[0046] Regarding the rotational motion of the outer permanent magnets, the outer permanent magnets can be connected to a rotation drive mechanism 130. The specific structure of the rotation drive mechanism 130 is not described in detail here. For example, the outer permanent magnets 120 can be directly connected to the drive shaft of the rotation drive motor, or the drive shaft of the rotation drive motor can be connected to a reduction mechanism, which is then connected to the outer permanent magnets 120 to drive the outer permanent magnets 120. A gear or sprocket can be coaxially fixedly connected to the outer side of the outer permanent magnets 120 and connected to the output end of the reduction mechanism.
[0047] Regarding the lifting motion of the outer permanent magnet, the outer permanent magnet and the rotary drive mechanism 130 can be placed on a lifting platform, and the lifting platform can be driven to move up and down by the lifting drive mechanism, so that the outer permanent magnet has the function of lifting. The lifting mechanism can be various commonly used structures, such as a ball screw pair, which can be connected to the ball screw pair by a stepper motor to drive the lifting platform to move up and down. Another example is a linear motion mechanism such as a cylinder, a hydraulic cylinder, a linear push rod, etc., which can directly connect its output end to the lifting platform to drive the lifting platform to move up and down. The specific structure is conventional technology and will not be described in detail here.
[0048] The inner side of the inner permanent magnet 110 can be fixedly connected to the wafer base 400 via the hollow rotating shaft 310. Specifically, the outer circumference of the hollow rotating shaft 310 is fixedly connected to the inner circumference of the inner permanent magnet 110, for example, by bonding or fastener connection. The upper end of the hollow rotating shaft 310 is fixedly connected to the wafer base 400. Therefore, the movement of the outer permanent magnet can drive the wafer base 400 to follow the same movement. When the outer permanent magnet 120 rises, the wafer base 400 also rises; when the outer permanent magnet descends, the wafer base 400 also descends. If the outer permanent magnet 120 rotates clockwise, the wafer base 400 also rotates clockwise; if the outer permanent magnet rotates counterclockwise, the wafer base 400 also rotates counterclockwise. If the outer permanent magnet 120 stops moving, the wafer base 400 also stops moving.
[0049] The sealing protective cover 300 is connected to the lower end of the pre-cleaning chamber, and the upper end of the sealing protective cover 300 is fixedly connected to the pre-cleaning chamber, so that the sealing protective cover 300 and the pre-cleaning chamber are sealed. In order to provide stable support for the hollow rotating shaft 310, a bearing can be installed between the sealing protective cover 300 and the hollow rotating shaft 310.
[0050] Conventional wafer pedestals use bellows to lift the wafer and wafer to the processing position. This long-term lifting motion can cause metal fatigue in the bellows, which can lead to cracks and chamber pressure leaks. Furthermore, the wafer remains stationary in the processing position, and the plasma generated by ionized argon gas randomly strikes the wafer surface, making it difficult to ensure uniform etching.
[0051] In this embodiment, the wafer base is driven by the magnetic drive unit 100, and the previous bellows that isolates the vacuum and the atmosphere (moving seal) are replaced with a sealing protective cover 300 that isolates the vacuum and the atmosphere (fixed seal), thereby avoiding the metal fatigue of the bellows caused by movement, which may lead to pressure leakage in the vacuum chamber. The outer permanent magnet 120 attracts the inner permanent magnet through the sealing protective cover 300 to achieve the purpose of synchronous movement between the inside and the outside, and at the same time, the movement of the wafer base is controlled by manipulating the movement of the outer permanent magnet 120. After the wafer base rises to the process position, the wafer base can also be controlled to rotate. Due to the rotation, each area of the top surface of the wafer can be more evenly exposed to the plasma, thereby improving the uniformity of wafer etching.
[0052] Please refer to Figure 2The RF signal transmission unit 200 includes a conductive slip ring 210, a brush 220, and an RF signal introduction rod 230. The sealing protective cover 300 has an opening at its lower end. The conductive slip ring 210 is inserted into the opening, with its outer wall fixedly connected to the opening. The conductive slip ring 210 is insulated from the sealing protective cover 300. The RF source signal line enters the conductive slip ring 210 through the opening at the lower end of the sealing protective cover 300 and is electrically connected to the conductive slip ring 210. The brush 220 is fixedly mounted at the bottom of the RF signal introduction rod 230 and is electrically connected to the rod 230. For example, the brush 220 is electrically connected to the outer circumference of the RF signal introduction rod 230. The outer side of the brush 220 is slidably connected to the conductive slip ring 210. This allows external RF signals to be transmitted to the wafer pedestal. When the wafer pedestal 400 is raised or lowered, the brush 220 can slide up and down to electrically connect to the conductive slip ring 210. When the wafer base 400 rotates, the brush 220 can be rotatably connected to the conductive slip ring 210 , thereby transmitting the radio frequency signal to the wafer base 400 in real time.
[0053] Please refer to Figure 4 The wafer base 400 includes a titanium disk 410 and a quartz disk 420. The upper end of the quartz disk 420 has a groove for accommodating the titanium disk 410. The titanium disk 410 is embedded in the groove, and a bolt passes through the titanium disk 410 and the quartz disk 420, and is screwed into the upper end of the RF signal introduction rod 230, so that the titanium disk 410 and the quartz disk 420 are fixedly connected to the RF signal introduction rod 230. There is a sunken wafer placement groove on the upper surface of the titanium disk 410, and the wafer 430 is placed in the wafer placement groove. Preferably, the upper surface of the titanium disk 410 is sunken by 0.5 mm to protect the wafer from being thrown out during the rotation of the wafer base 400.
[0054] In addition, a shielding cover (Lower shield) 600 is fixedly connected to the outer periphery of the wafer base 400, and the shielding cover 600 surrounds the lower end and side of the wafer base. The shielding cover is made of conductive material, and a conductive ring 620 is provided on the side wall of the pre-cleaning chamber. The conductive ring 20 is circumferentially arranged on the side wall of the pre-cleaning chamber, and preferably can be embedded in the side wall. A fiber brush bundle 610 is also fixedly connected to the shielding cover. The shielding cover 600 moves together with the wafer base 400, so the fiber brush bundle 610 also moves together with the wafer base 400. Moreover, during the movement, the fiber brush bundle 610 and the conductive ring 620 always maintain a conductive connection. For example, when the wafer base 400 rotates, the fiber brush bundle 610 always maintains a conductive connection with the conductive ring 620 during the rotation.
[0055] In some embodiments, there are also lifting pins 500, which are vertical rods evenly distributed in the circumference and can be raised and lowered in the vertical direction. Figure 5 The wafer base 400 has a plurality of corresponding holes 510. When the wafer base 400 is lowered until the lifting pins are inserted into the holes 510, the wafer base 400 cannot rotate. When the wafer base 400 needs to be rotated, the lifting drive mechanism drives the magnetic drive unit 100 to rise, thereby causing the hollow rotating shaft 310 to rise together with the wafer base 400. When the wafer base rises to the process position, it has been freed from the constraints of the lifting pins 500 and can be rotated by the magnetic drive unit 100.
[0056] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications shall fall within the scope of protection of the claims of the present invention.
Claims
1. A wafer pre-cleaning chamber, characterized in that: include: A sealing protective cover, one end of which is sealed and connected to the pre-cleaning chamber, and the other end of which has an opening; A magnetic driving unit, comprising an outer permanent magnet disposed outside the sealing protective cover and an inner permanent magnet disposed inside the sealing protective cover, wherein the inner side of the inner permanent magnet is fixedly connected to the wafer base via a hollow rotating shaft; The radio frequency signal transmission part includes a conductive slip ring, a brush, and a radio frequency signal introduction rod. The conductive slip ring is inserted into the opening and fixedly connected to the opening. The radio frequency signal introduction rod sequentially passes through the conductive slip ring and the inner side of the hollow rotating shaft and is fixedly connected to the wafer base. The brush is fixedly connected to the lower part of the radio frequency signal introduction rod and is conductively connected to the radio frequency signal introduction rod. The outer side of the brush is slidably and conductively connected to the inner side of the conductive slip ring.
2. The wafer pre-cleaning chamber according to claim 1, characterized in that: A shielding cover is also fixedly connected to the outer periphery of the wafer base, and the shielding cover surrounds the lower end and side surfaces of the wafer base. The shielding cover is made of conductive material, and a conductive ring is arranged on the side wall of the pre-cleaning chamber. The conductive ring is circumferentially arranged on the side wall of the pre-cleaning chamber. A fiber brush bundle is also fixedly connected to the shielding cover, and the fiber brush bundle maintains conductive connection with the conductive ring.
3. The wafer pre-cleaning chamber according to claim 2, characterized in that: The conductive ring is embedded on a side wall of the pre-cleaning chamber.
4. The wafer pre-cleaning chamber according to claim 1, characterized in that: The inner layer permanent magnet and the outer layer permanent magnet are annular, and are formed by stacking a plurality of magnets along the axial direction and the circumferential direction of the hollow rotating shaft, and the magnetic poles of adjacent magnets are opposite.
5. The wafer pre-cleaning chamber according to claim 1, characterized in that: The outer layer permanent magnets are connected to the rotary drive mechanism. The outer layer permanent magnets and the rotary drive mechanism are both placed on the lifting platform. The lifting platform is driven to rise and fall by the lifting drive mechanism.
6. The wafer pre-cleaning chamber according to claim 5, characterized in that: The lifting drive mechanism is a ball screw pair.
7. The wafer pre-cleaning chamber according to claim 1, characterized in that: The conductive slip ring is insulated from the sealing protection cover.
8. The wafer pre-cleaning chamber according to claim 1, characterized in that: The wafer base includes a titanium plate and a quartz plate. The titanium plate is embedded in a groove at the upper end of the quartz plate. The titanium plate and the quartz plate are fixedly connected to the upper end of the RF signal introduction rod by fasteners. A sunken wafer placement groove is provided on the upper surface of the titanium plate.
9. The wafer pre-cleaning chamber according to claim 8, characterized in that: It also has a lifting pin, which is a vertical rod evenly distributed in the circumferential direction, and has a plurality of corresponding holes on the wafer base. When the wafer base is lowered to the point where the lifting pin is inserted into the hole, the wafer base is subject to rotational constraint. When the wafer base is raised to the point where the lifting pin comes out of the hole, it is not subject to rotational constraint.
10. The wafer pre-cleaning chamber according to claim 1, characterized in that: The brush is conductively connected to the outer circumference of the radio frequency signal introduction rod.