Wafer air floating positioning device

Abstract

The application discloses a wafer air floating positioning device, which comprises a disc body, wherein the disc body is provided with a plurality of air holes with orifices formed on the surface of the disc body, and a part of the air holes are arranged as positive pressure holes for spraying gas from the orifices, and the other part of the air holes are arranged as negative pressure holes for sucking gas from the orifices, so that the surface of the disc body forms an air film for suspending the wafer. The wafer can be effectively prevented from being damaged.

Description

Technical Field

[0001] This invention relates to an air-floating positioning device for wafers, belonging to the technical field of precision semiconductor equipment. Background Technology

[0002] In the wafer fabrication process, a positioning device is needed to hold and position the wafer to ensure stability and accuracy during inspection, thus meeting inspection requirements. Existing positioning devices position the wafer, with its bottom surface directly contacting the positioning device's disk. A clamping component then holds the wafer at the top edge, clamping it from above and below. This direct contact between the disk and the wafer makes the wafer surface vulnerable to damage, and the clamping component's contact with the wafer edge can also cause damage. Furthermore, the clamping method and the direct contact between the disk and the wafer can lead to significant chip loss, which is detrimental to wafer inspection. Summary of the Invention

[0003] The purpose of this invention is to provide an air-floating positioning device for wafers, which can effectively prevent wafer damage.

[0004] This invention is achieved through the following technical solutions.

[0005] An air-floating positioning device for wafers, comprising:

[0006] The disk has multiple pores with orifices on its surface. Some of the pores are configured as positive pressure orifices for gas to be ejected from their orifices, while others are configured as negative pressure orifices for gas to be drawn in from their orifices, so that a gas film for suspending the wafer is formed on the surface of the disk.

[0007] As a further improvement of the present invention, the surface of the disc body is defined with a plurality of concentric rings centered on the center of the disc body, and the plurality of concentric rings are alternately set as positive pressure concentric rings and negative pressure concentric rings in the radial direction. Positive pressure holes are arranged at intervals along the circumference of the positive pressure concentric rings, and negative pressure holes are arranged at intervals along the negative pressure concentric rings.

[0008] As a further improvement of the present invention, the surface of the disc body is defined with a plurality of radially arranged arched airflow ring regions, each arched airflow ring region including two adjacent positive pressure concentric rings and negative pressure concentric rings, and the axial directions of the positive pressure holes and negative pressure holes are configured to such that the air film body corresponding to the arched airflow ring region is formed by arched airflow.

[0009] As a further improvement of the present invention, the surface of the disc has an annularly extended and protruding flow-blocking dam between any two adjacent concentric rings, which is used to block gas located in the same arched airflow ring area that has not formed an arched airflow.

[0010] As a further improvement of the present invention, the surface shape of the flow barrier matches the flow direction of the arched airflow and forms a guide wall to guide the gas ejected from the positive pressure hole to flow towards the negative pressure hole along the predetermined flow direction of the arched airflow.

[0011] As a further improvement of the present invention, a support portion is formed at the top of the flow barrier to support the wafer before the gas film is formed, and to make its bottom surface and the positive pressure hole and the negative pressure hole have a spacing distance.

[0012] As a further improvement of the present invention, the surface of the support portion is configured as an arcuate surface.

[0013] As a further improvement of the present invention, the outermost concentric ring is set as a positive pressure concentric ring, and the positive pressure hole thereto is suitable for the ejected gas to form an air wall on the outer ring of the air film to block the intrusion of external particles.

[0014] As a further improvement of the present invention, the air holes on the disc are evenly arranged.

[0015] As a further improvement of the present invention, it also includes a plurality of limiting posts disposed on the edge of the disk body, the limiting posts being able to contact the edge of the wafer to prevent the wafer from shifting relative to the disk body.

[0016] The beneficial effects of this invention are:

[0017] Through the synergistic effect of positive and negative pressure orifices, a gas film suspending the wafer is formed on the disk surface, achieving non-contact positioning. This fundamentally avoids direct contact between the wafer's bottom surface and the disk, significantly reducing physical damage to the wafer surface and particulate contamination caused by friction. The design of the arched airflow ring area, by setting the inclined axes of the positive and negative pressure orifices, guides the gas to form an arched flow path. This not only enables the gas film to generate an upward lifting force to smoothly suspend the wafer, but also greatly enhances the stability and envelopment of the airflow, reducing turbulence and wafer jitter, thereby improving positioning accuracy and the stability of the detection process. The design of the flow barrier effectively blocks the ineffective horizontal airflow that fails to participate in forming the arched airflow, guiding it to an effective path, thereby significantly improving gas utilization efficiency and gas film formation speed, reducing energy consumption, and making the pressure distribution under the wafer more uniform. Attached Figure Description

[0018] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings to aid in understanding the objectives and advantages of the present invention, wherein:

[0019] Figure 1 This is a top view of the positioning device;

[0020] Figure 2 This is a cross-sectional schematic diagram of the positioning device;

[0021] Figure 3 for Figure 2 A magnified view of a portion of the image. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0023] In this specification, the directional terms such as up, down, left, right, front, back, front, back, top, and bottom, as mentioned or possibly used, are defined relative to the construction shown in the accompanying drawings. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0024] This embodiment illustrates an air-floating positioning device for a wafer, with reference to... Figures 1-3 The positioning device includes a disc body 1 with multiple air holes on its surface, forming orifices. Some of these air holes are designated as positive pressure holes h1, through which gas is ejected; others are designated as negative pressure holes h2, through which gas is drawn in. The positive pressure holes h1 are typically connected to one or more external fans, which provide compressed gas, creating a positive pressure state at the positive pressure holes h1, thus ejecting gas. The negative pressure holes h2 are connected to one or more vacuum pumps, which generate negative pressure, creating a suction airflow at the negative pressure holes h2. When the disc body 1 is operating, the gas ejected from the positive pressure holes h1 interacts with the gas drawn in from the negative pressure holes h2, forming a stable gas film above the surface of the disc body 1. This air film suspends the wafer, preventing it from directly contacting the surface of the disk 1 during inspection. This avoids wear or contamination of the wafer's bottom surface caused by prolonged contact. This non-contact suspension method not only reduces physical damage to the wafer surface but also significantly reduces particle generation because there is no friction between the wafer and the disk 1, thus improving the cleanliness and integrity of the wafer during inspection. Furthermore, the presence of the air film allows the wafer to be uniformly supported, reducing local stress concentration and further protecting the wafer's fragile structure. Especially for thin or large wafers, this suspension method effectively prevents bending or breakage, improving the reliability and accuracy of inspection.

[0025] In this embodiment, to improve the uniformity and stability of the gas film, the surface of the disk 1 is defined with multiple concentric rings centered on the center of the disk 1. These concentric rings are alternately arranged radially as positive pressure concentric rings c1 and negative pressure concentric rings c2. That is, from the center of the disk 1 outwards, the first ring may be a positive pressure concentric ring c1, the second a negative pressure concentric ring c2, the third a positive pressure concentric ring c1 again, and so on. Positive pressure holes h1 are arranged at intervals along the circumference of the positive pressure concentric rings c1, while negative pressure holes h2 are arranged at intervals along the negative pressure concentric rings c2. This alternating arrangement makes the positive pressure holes h1 and negative pressure holes h2 form a regular distribution on the surface of the disk 1. When gas is ejected from the positive pressure holes h1 and drawn in by the negative pressure holes h2, a uniform airflow field can be generated on the entire surface of the disk 1, thereby forming a more stable and continuous gas film. The arrangement of the positive-pressure concentric rings c1 and c2 avoids the problem of excessive concentration or sparseness of airflow in local areas, ensuring uniform force when the wafer is suspended and reducing the possibility of positional displacement or jitter. At the same time, the concentric ring layout allows the air film to adapt to wafers of different sizes, because the airflow pattern is centrally symmetrical, and the wafer can obtain a consistent support effect.

[0026] In this embodiment, to further improve the morphology and efficiency of the air film, the surface of the disk 1 defines multiple radially arranged arched airflow annular regions r. Each arched airflow annular region r includes two adjacent positive pressure concentric rings c1 and negative pressure concentric rings c2, i.e., one positive pressure concentric ring c1 and one negative pressure concentric ring c2 are paired to form an annular region. The axial directions of the positive pressure orifice h1 and the negative pressure orifice h2 are configured to allow the gas ejected from the positive pressure orifice h1 and the gas drawn in by the negative pressure orifice h2 to work synergistically to form an arched airflow within the arched airflow annular region r. More specifically, the axial directions of the positive pressure orifice h1 and the negative pressure orifice h2 are parallel to the radial section of the disk 1 corresponding to the orifice, and the axial directions of the positive pressure orifice h1 and the negative pressure orifice h2 are opposite, both inclined in the vertical direction, with an inclination angle between 15° and 30°. This tilted design prevents the gas ejected from the positive pressure port h1 from directly impacting the bottom surface of the wafer vertically. Instead, it guides the gas at a certain angle to the negative pressure port h2, thus forming an arched airflow path below the wafer. This arched airflow generates an upward lift, smoothly supporting the wafer. Simultaneously, the arc-shaped structure of the airflow makes the gas flow smoother, reducing turbulence and energy loss. This not only improves the efficiency of gas film formation but also enhances wafer stability. Furthermore, this arched airflow reduces localized impacts on the bottom surface of the wafer, lowering the risk of wafer vibration due to airflow fluctuations. This keeps the wafer stationary during inspection, improving positioning accuracy.

[0027] In this embodiment, based on considerations of optimizing airflow utilization and reducing waste, the surface of the disk 1 has a circumferentially extending and protruding flow barrier 3 between any two adjacent concentric rings. Due to the axial direction of the positive pressure hole h1, some of the gas ejected from the positive pressure hole h1 does not completely form an arched airflow. Instead, some gas flows in a relatively horizontal direction and is directly sucked in by the negative pressure hole h2. This airflow fails to effectively participate in the formation of the gas film, resulting in low gas utilization efficiency. The function of the flow barrier 3 is to block these gases that do not form an arched airflow, forcing them to change their flow direction and participate more in the formation of the arched airflow. The flow barrier 3 protrudes from the surface of the disk 1 and is located between the positive pressure concentric ring c1 and the negative pressure concentric ring c2. Its annular structure can effectively intercept horizontally flowing gas, causing the gas to change direction along the contour of the flow barrier 3, thereby enhancing the effect of the arched airflow. The design of the flow barrier 3 not only improves the efficiency of gas film formation and reduces the energy consumption of fans and vacuum equipment, but also makes the gas film denser and more stable. As the airflow is effectively guided, the air pressure distribution under the wafer is more uniform, avoiding local low-pressure or high-pressure areas, thereby reducing the swaying of the wafer when it is suspended.

[0028] In this embodiment, to further optimize the airflow guiding effect, the surface shape of the flow barrier 3 matches the flow direction of the arched airflow and forms a guide wall 31. More specifically, the flow barrier 3 gradually rises and then gradually decreases from its outer ring to its inner ring, thereby forming a smooth arc-shaped profile. The guide wall 31 reduces the resistance to gas flow, allowing the airflow to form the arched structure more smoothly. This guiding effect improves the synergy of the airflow, making the airflow coupling between the positive and negative pressure holes h2 tighter, thereby enhancing the integrity and strength of the air film.

[0029] In this embodiment, to protect the wafer from damage in the initial stage, a support portion 32 is formed on the top of the flow barrier 3 to support the wafer before the gas film forms. During the positioning process, the wafer is first placed on the disk 1 by a robotic arm. At this time, the gas film has not yet formed, and the wafer is briefly placed on the support portion 32 formed on the top of the flow barrier 3. In this way, a certain distance is maintained between the bottom surface of the wafer and the positive pressure hole h1 and the negative pressure hole h2. Without the flow barrier 3 and the support portion 32, the wafer would be placed directly on the surface of the disk 1. When the positive pressure hole h1 and the negative pressure hole h2 start working, the instantaneous action of gas ejection and suction would generate a strong impact or suction on the bottom surface of the wafer, which could easily lead to damage to the bottom surface of the wafer, such as micro-scratches or stress cracks. By pre-lifting the wafer by the support portion 32, the airflow can start to act from the distance during the gas film formation process, avoiding direct contact. This spacing allows the gas ejected from the positive pressure hole h1 to diffuse before reaching the bottom surface of the wafer, increasing its effective range and reducing the airflow pressure per unit area, further minimizing damage to the wafer bottom surface in the initial stage. Simultaneously, the spacing allows for a smoother gas film formation, gently lifting the wafer from the support 32 with a natural transition and avoiding sudden force changes. This not only protects the wafer's integrity but also improves the reliability and safety of the positioning process.

[0030] In this embodiment, to further reduce the potential impact of the support portion 32 on the wafer bottom surface, the surface of the support portion 32 is configured as an arc-shaped surface. The arc-shaped surface design minimizes the contact area between the support portion 32 and the wafer bottom surface, and the contact point has a smooth curve, avoiding stress concentration caused by sharp corners or edges. The support portion 32 can be made of polyetheretherketone (PEEK) material, which has a moderate surface resistivity, ranging from 10^6 to 10^8 Ω, effectively preventing static electricity buildup and avoiding damage to the wafer circuitry caused by electrostatic discharge. Simultaneously, PEEK material has a low coefficient of friction, approximately 0.25 for silicon wafers. This means that when the wafer is placed on the support portion 32, the frictional resistance during sliding or movement is very small, further reducing the risk of scratches. Furthermore, the arc-shaped surface facilitates smooth airflow transition. When an air film forms, the airflow can smoothly wrap around the wafer along the arc-shaped surface, reducing turbulence and thus improving the stability of the suspension.

[0031] In this embodiment, to enhance the sealing and anti-contamination capabilities of the gas film, the outermost concentric ring is configured as a positive pressure concentric ring c1. Its corresponding positive pressure orifice h1 is adapted to form an air wall around the outer edge of the gas film, acting as a gas barrier to prevent the intrusion of external particles. When the wafer is suspended, the outermost positive pressure orifice h1 continuously ejects gas, forming an outward airflow wall. This airflow wall not only helps maintain the edge stability of the gas film but also prevents dust or contaminants from the outside air from entering the area between the wafer and the disk 1.

[0032] In this embodiment, in order to ensure uniform coverage of the gas film and balanced suspension of the wafer, the air holes on the disk 1 are evenly arranged, which evens out the pressure distribution of the gas film and is beneficial to the air-floating state of the wafer.

[0033] In this embodiment, to prevent the wafer from shifting position during levitation, the positioning device further includes multiple limiting posts 21 disposed on the edge of the disk 1. These limiting posts 21 can contact the edge of the wafer. When the wafer is levied by the gas film, the limiting posts 21 act as a physical barrier to prevent the wafer from shifting position relative to the disk 1 due to airflow fluctuations or external interference. The limiting posts 21 are also made of polyetheretherketone (PEEK) material to reduce damage to the wafer.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions 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 positioning device for a wafer, characterized in that, include: The disk body (1) is provided with a plurality of air holes forming orifices on its surface. A portion of the air holes are configured as positive pressure holes (h1) from which gas is ejected, and another portion of the air holes are configured as negative pressure holes (h2) from which gas is drawn in, so that an air film for suspending the wafer is formed on the surface of the disk body (1). The surface of the disk body (1) is defined with a plurality of concentric rings centered on the center of the disk body (1). The plurality of concentric rings are alternately set as positive pressure concentric rings (c1) and negative pressure concentric rings (c2) in the radial direction. The positive pressure holes (h1) are arranged at intervals along the circumference of the positive pressure concentric rings (c1), and the negative pressure holes (h2) are arranged at intervals along the negative pressure concentric rings (c2). The surface of the disk (1) is defined with a plurality of radially arranged arched airflow ring zones (r), each of the arched airflow ring zones (r) including two adjacent positive pressure concentric rings (c1) and negative pressure concentric rings (c2), and the axial directions of the positive pressure holes (h1) and the negative pressure holes (h2) are configured to be such that the air film body corresponding to the arched airflow ring zone (r) is formed by the arched airflow; The surface of the disc (1) has an annularly extended and raised flow barrier (3) between any two adjacent concentric rings, which is used to block gas located in the same arched airflow ring area (r) and which has not formed an arched airflow.

2. The positioning device according to claim 1, characterized in that, The surface shape of the flow barrier (3) matches the flow direction of the arched airflow and forms a guide wall (31) to guide the gas ejected from the positive pressure hole (h1) to flow towards the negative pressure hole (h2) along the predetermined flow direction of the arched airflow.

3. The positioning device according to claim 2, characterized in that, The top of the flow barrier (3) forms a support (32) to support the wafer before the gas film is formed, and to make its bottom surface and the positive pressure hole (h1) and the negative pressure hole (h2) spaced apart.

4. The positioning device according to claim 3, characterized in that, The surface of the support (32) is configured as an arcuate surface.

5. The positioning device according to any one of claims 1-3, characterized in that, The outermost concentric ring is configured as the positive pressure concentric ring (c1), and the positive pressure hole (h1) to which it belongs is adapted to form an air wall on the outer ring of the air film to block the intrusion of external particles.

6. The positioning device according to any one of claims 1-3, characterized in that, The air holes on the disc (1) are evenly arranged.

7. The positioning device according to any one of claims 1-3, characterized in that, It also includes a plurality of limiting posts (21) disposed on the edge of the disk body (1), the limiting posts (21) being able to contact the edge of the wafer to place the wafer at a position offset relative to the disk body (1).

Images