retaining mechanism

Abstract

The present application provides a holding mechanism that uses a Bernoulli pad to attract and hold a plate-shaped object without damaging the plate-shaped object. The holding mechanism has a Bernoulli pad that holds a plate-shaped object by the action of negative pressure generated by blowing air against the plate-shaped object, and has a hand portion to which the Bernoulli pad is attached, a sensor attached to the hand portion that detects when the plate-shaped object is held by the Bernoulli pad, a lateral movement restriction portion attached to the hand portion that restricts lateral movement of the plate-shaped object, a tube that connects an air source that supplies air to the Bernoulli pad to the Bernoulli pad, an adjustment valve attached to the tube that adjusts the flow rate of air supplied to the Bernoulli pad, and a control portion that controls the operation of the adjustment valve. The control portion gradually increases the flow rate of air supplied from the adjustment valve to the Bernoulli pad, and fixes the flow rate of air when the plate-shaped object is held by the Bernoulli pad by the action of negative pressure detected by the sensor.

Description

Technical Field

[0001] The present invention relates to a holding mechanism having a Bernoulli pad that holds the plate by means of negative pressure generated by blowing air onto the plate. Background Technology

[0002] Device chips are incorporated into electronic devices such as mobile phones and personal computers. These device chips are obtained, for example, by thinning the entire back side of a wafer on which multiple devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integrations) are formed on the front side using a grinding device, and then dividing the thinned wafer using a cutting device or a laser processing device.

[0003] On the front side of the wafer before dicing, multiple predetermined dicing lines are arranged in a grid pattern, and the aforementioned devices are formed in multiple regions divided by these predetermined dicing lines. Around the device regions on the front side of the wafer where multiple devices are formed, there exists a ring-shaped peripheral region where no devices are formed.

[0004] Furthermore, in the manufacturing of device chips, there is a method where, instead of grinding the outer periphery of the back side corresponding to the remaining outer periphery region, the central portion of the back side corresponding to the device region is ground, thereby thinning the back side and forming a recess. In this case, the outer periphery functions as a thicker reinforcing portion, thus achieving effects such as reducing wafer warpage and increasing wafer strength.

[0005] However, when the thickness of the wafer corresponding to the device region is reduced to, for example, about 30 μm, the wafer may break when the adsorption pad is brought into contact with the device region for transport. Therefore, a holding mechanism with a Bernoulli pad that holds the wafer in a non-contact manner with the device region has been developed (for example, see Patent Document 1).

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-142462

[0007] Bernoulli pads use negative pressure generated by blowing air onto the wafer to attract and hold it. Higher air pressure produces higher negative pressure, but also increases the impact force of the air on the wafer, potentially causing it to vibrate and break. Furthermore, this problem of wafer vibration and breakage can also occur in conventional wafers where no recess is formed on the back side. Summary of the Invention

[0008] The present invention was made in view of this problem, and its object is to hold a plate-shaped object such as a wafer by attraction without breaking the plate-shaped object when using a Bernoulli pad to hold the plate-shaped object.

[0009] According to one aspect of the invention, a holding mechanism is provided, which has a Bernoulli pad that holds the plate by means of negative pressure generated by blowing air onto the plate. The holding mechanism includes: a hand with the Bernoulli pad disposed thereon; a sensor disposed thereon for detecting whether the plate is held by the Bernoulli pad; a lateral movement limiting part disposed thereon for limiting lateral movement of the plate; a pipe connecting an air source supplying air to the Bernoulli pad; an adjusting valve disposed thereon for adjusting the flow rate of air supplied to the Bernoulli pad; and a control part that controls the operation of the adjusting valve, the control part gradually increasing the flow rate of air supplied from the adjusting valve to the Bernoulli pad, and fixing the air flow rate when the sensor detects that the plate is held by the Bernoulli pad under negative pressure.

[0010] Preferably, the sensor is a proximity sensor. When the sensor detects that the distance between the sensor and the plate is a predetermined length, the control unit determines that the plate is attracted and held by the Bernoulli pad, and fixes the flow rate of air supplied from the adjustment valve to the Bernoulli pad.

[0011] Alternatively, the sensor is preferably a vibration sensor. When the sensor detects that the amplitude of the vibration of the plate gradually increases with the increase of air flow and reaches a predetermined amount, the control unit determines that the plate is attracted and held by the Bernoulli pad, and fixes the air flow supplied from the regulating valve to the Bernoulli pad.

[0012] In one embodiment of the holding mechanism of the present invention, the control unit gradually increases the airflow supplied from the adjusting valve to the Bernoulli pad, and fixes the airflow when the sensor detects that the plate is being held by the Bernoulli pad under negative pressure. That is, excessive increase in air impact force can be avoided, and thus the plate can be held appropriately by attraction without damaging it. Attached Figure Description

[0013] Figure 1 It is a three-dimensional diagram of the mechanism, etc.

[0014] Figure 2 It is a magnified three-dimensional view of one side of the hand.

[0015] Figure 3 This diagram illustrates a situation where the wafer is held in place by adjusting the airflow.

[0016] Figure 4 This is a flowchart illustrating the process of attracting and holding a wafer by adjusting the airflow.

[0017] Label Explanation

[0018] 2: Holding mechanism; 4: Linkage mechanism; 6: First drive unit; 8: Support component; 10: First link; 11: Wafer; 11a: Front side; 11b: Back side; 12: Second link; 13: Device; 14: Second drive unit; 16: Hand; 16a: Base; 16b: Front end; 16c: Cutout; 16d: One side; 16e: The other side; 18a, 18b: Bernoulli pad; 20: Rubber pad; 22: Sensor; 24: Box; 24a: Side; 24b: Support groove; 24c: Top plate; 24d: Connecting part; 24e: Opening; 26: Air pipe; 26a: Main plug; 28: Air supply source; 30: Electric air compressor regulator; 32: Control unit; A: Distance. Detailed Implementation

[0019] Referring to the accompanying drawings, an embodiment of one aspect of the present invention will be described. First, the holding mechanism 2 will be described. This holding mechanism 2 is mounted on a processing device (not shown) such as a cutting device, grinding device, laser processing device, or bonding device, and conveys the wafer (plate) 11, which is the object to be processed. Figure 1 It is a three-dimensional diagram of the retaining mechanism 2, etc.

[0020] The retaining mechanism 2 has a first drive unit 6. The first drive unit 6 has an electric motor or the like (not shown) and is capable of moving the cylindrical support member 8, which is connected to the upper part of the first drive unit 6, up and down along the Z-axis, or rotating about a rotation axis that is approximately parallel to the Z-axis.

[0021] One end of the first link 10 is connected to the upper part of the support member 8 in a manner that allows it to rotate about a rotation axis that is approximately parallel to the Z-axis direction. The bottom of one end of the second link 12 is connected to the upper part of the other end of the first link 10 in a manner that allows it to rotate about a rotation axis that is approximately parallel to the Z-axis direction.

[0022] At the upper part of the other end of the second link 12, the bottom of the second drive unit 14 is connected in a manner that allows it to rotate about a rotation axis that is approximately parallel to the Z-axis direction. On the side of the second drive unit 14, a hand part 16 is connected in a manner that allows it to rotate about a predetermined straight line that is approximately parallel to the XY plane.

[0023] Here, refer to Figure 2 The structure of the hand part 16 in the first embodiment will be described. Figure 2 This is an enlarged perspective view of one face 16d of the hand part 16. The hand part 16 has a rectangular plate-shaped base 16a at one end connected to the second drive part 14.

[0024] At the other end of the base 16a, there is an arc-shaped front end portion 16b, which is the same as the base 16a and is made of a metal such as stainless steel. The arc formed by the front end portion 16b has a central angle of more than 270 degrees. In this example, the front end portion 16b has a cut 16c on the side opposite to the other end of the base 16a relative to the center of the arc, with a width approximately the same as that of the base 16a.

[0025] A plurality of Bernoulli pads 18a and 18b are provided on one side of the face 16d of the front end 16b. Specifically, with an imaginary straight line connecting the cutout 16c and the base 16a as the center, three Bernoulli pads 18a are arranged on one side and three Bernoulli pads 18b are arranged on the other side in a linearly symmetrical manner.

[0026] Each Bernoulli pad 18a, 18b ejects air to create a swirling flow in a direction from the other side 16e of the front end 16b toward one side 16d. The Bernoulli pads 18a, 18b are substantially the same, but for example, to prevent the rotation of the attracted object, the direction of rotation of the swirling flow of the Bernoulli pads 18a, 18b is set to be opposite.

[0027] Near the axis of rotation of the swirling flow, according to Bernoulli's theorem, the pressure decreases, thereby generating negative pressure. The wafer 11, located near the hand 16, is held in a non-contact manner by the Bernoulli pads 18a, 18b by the balance between the upward force generated by the negative pressure and the downward force generated by the impact force of the air and the weight of the wafer 11.

[0028] A rubber pad (lateral movement restriction part) 20, for example made of rubber sheet, is provided between each of the three Bernoulli pads 18a. Similarly, a rubber pad 20 is also provided between each of the three Bernoulli pads 18b.

[0029] The rubber pad 20 protrudes by a greater amount than the Bernoulli pad 18a protruding from one surface 16d. The protrusion of the rubber pad 20 is adjusted to allow it to contact the wafer 11 when the wafer 11 is attracted using the Bernoulli pads 18a and 18b.

[0030] Therefore, when the wafer 11 is held in place by Bernoulli pads 18a and 18b, the rubber pad 20 restricts the lateral movement of the wafer 11 parallel to the XY plane. Alternatively, instead of the rubber pad 20, a guide, pin, or the like (lateral movement limiting part) for restricting the lateral movement of the wafer 11 may be provided on the hand part 16.

[0031] A sensor 22 is disposed between the Bernoulli pads 18a and 18b, respectively, located closest to the base 16a. This sensor 22 is used to detect whether the wafer 11 is attracted and held by the Bernoulli pads 18a and 18b. The sensor 22 in this embodiment is an electrostatic capacitive proximity sensor capable of measuring the distance from the detector of the sensor 22 to the wafer 11.

[0032] The electrostatic capacitance of sensor 22 is determined by the distance A between the detector of sensor 22 and chip 11 (reference). Figure 3 The electrostatic capacitance detected by sensor 22 is output to control unit 32 (described later), and converted into distance A by control unit 32.

[0033] Here, refer to Figure 1 The wafer 11 will be described below. The wafer 11 is formed of a semiconductor material such as silicon. On the front side 11a of the wafer 11, a plurality of pre-defined dividing lines (spacers) are arranged in a grid pattern. In the multiple regions divided by the multiple pre-defined dividing lines, devices such as ICs (Integrated Circuits) are formed respectively.

[0034] Furthermore, there are no restrictions on the material, shape, structure, or size of the chip 11. For example, the chip 11 can also be formed from materials other than silicon, such as semiconductors, ceramics, resins, or metals. Similarly, there are no restrictions on the type, quantity, shape, structure, size, or arrangement of the devices 13.

[0035] Multiple wafers 11 are housed in a housing 24. The housing 24 has a pair of sides 24a. On the inner surface of each side 24a, a plurality of support grooves 24b are formed at predetermined intervals along the height direction of the housing 24. A wafer 11 is housed in a pair of opposing support grooves 24b.

[0036] The upper parts of a pair of side surfaces 24a are connected by a top plate 24c, and the lower parts of the pair of side surfaces 24a are connected by an elongated plate-shaped connecting part 24d. In addition, an opening 24e is formed at one end (front part) of the pair of side surfaces 24a in the width direction.

[0037] After the hand 16 is inserted into the housing 24 through the opening 24e and one surface 16d of the hand 16 is positioned above the wafer 11, when air is blown onto the wafer 11 from the Bernoulli pads 18a and 18b, the wafer 11 is attracted to one surface 16d (see reference). Figure 3 ).

[0038] like Figure 3 As shown, an air supply source (air source) 28 is connected to the Bernoulli pads 18a and 18b via an air pipe 26. The air supply source 28 includes a compressor for compressing and delivering air, a container for storing the compressed air, etc.

[0039] An electric air compressor regulator (adjusting valve) 30 is provided on the air pipe 26. The electric air compressor regulator 30 is a proportional control valve that can continuously control the pressure of the air output according to the input signal, and has a controller (not shown) that controls the operation of the exhaust valve and the air supply valve (both not shown).

[0040] The controller controls the air pressure at the output port of the electric air compressor regulator 30 by controlling the opening and closing of the exhaust valve and the air supply valve. In addition, air is supplied from the air supply source 28 to the air supply valve via the air pipe 26, and the air adjusted to a specified pressure is supplied from the output port to the downstream air pipe 26.

[0041] The electric air compressor regulator 30 is equipped with a pressure sensor (not shown) that monitors the air pressure at the output port. When an input signal specifying the air pressure value to be output from the output port is input to the controller, the controller controls the exhaust valve and the supply valve according to the input signal, and receives feedback of the pressure value obtained from the pressure sensor.

[0042] The controller uses pressure feedback to control the exhaust valve and the supply valve so that the air pressure at the output port reaches the specified pressure value. Thus, the air pressure at the output port is corrected.

[0043] The air pressure at the output port is adjusted by inputting an input signal to the controller, thereby adjusting the air flow rate (i.e., the flow rate per unit time) supplied to the Bernoulli pads 18a and 18b. For example, by continuously changing the air pressure at the output port using the input signal, the air flow rate from the output port can be continuously changed.

[0044] Specifically, the higher the air pressure at the output port, the greater the airflow from the output port; conversely, the lower the air pressure at the output port, the less the airflow from the output port.

[0045] A main valve 26a, including a manual valve, is provided between the air supply source 28 and the electric air pressure regulator 30. When the main valve 26a is in the open state, air is supplied from the air supply source 28 to the air supply port of the electric air pressure regulator 30 at a pressure of approximately 0.3 MPa.

[0046] The operation of the electric air compressor regulator 30 is controlled by the control unit 32. The control unit 32 is the main control unit of the aforementioned processing device, but it also controls the various components of the holding mechanism 2, such as the linkage mechanism 4, Bernoulli pads 18a and 18b, and sensor 22.

[0047] The control unit 32 may be composed of, for example, a computer, which includes: a processing device such as a processor (CPU); a main storage device such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), and ROM (Read Only Memory); and auxiliary storage devices such as flash memory, hard disk drives, and solid-state drives.

[0048] The auxiliary storage device stores software containing a prescribed program. The function of the control unit 32 is realized by operating the processing device and the like according to the software. Next, the method by which the control unit 32 attracts and holds the wafer 11 using Bernoulli pads 18a and 18b by adjusting the air flow will be described.

[0049] Figure 3 This diagram illustrates the situation where the wafer 11 is attracted and held by adjusting the airflow. Figure 4 This is a flowchart illustrating the process of attracting and holding the wafer 11 by adjusting the airflow. Furthermore, in... Figure 3 Bernoulli pads 18a and 18b and rubber pad 20 are omitted.

[0050] When attracting and holding the wafer 11, firstly, the linkage mechanism 4 is activated to position the hand 16 above one of the wafers 11 housed in the housing 24. In this embodiment, one face 16d of the hand 16 faces the front face 11a of the wafer 11, but if the back face 11b of the wafer 11 is facing upwards, one face 16d of the hand 16 may also face the back face 11b.

[0051] Next, the input signal to the electric pneumatic regulator 30 is controlled to gradually increase the air flow rate supplied from the electric pneumatic regulator 30 to the Bernoulli pads 18a and 18b from zero (air flow rate increase step S10).

[0052] The control unit 32 monitors the distance A between the detector of the sensor 22 and the chip 11 in real time by monitoring the electrostatic capacitance of the sensor 22. When the distance A does not reach the predetermined length, the control unit 32 determines that the chip 11 is not attracted and held ("No" in S20) and continues to increase the air flow.

[0053] In contrast, when the sensor 22 detects that the distance A has reached a predetermined length, the control unit 32 determines that the wafer 11 is attracted and held (in S20, this is "yes"). Furthermore, the predetermined length of the distance A varies depending on the diameter, thickness, material, etc. of the wafer 11.

[0054] For example, if wafer 11 is a silicon wafer with a diameter of 300 mm, a thickness of 100 μm for the outer periphery corresponding to the remaining outer periphery region, and a thickness of 30 μm for the portion corresponding to the device region, then the specified length of distance A is 0.5 mm.

[0055] When the distance A becomes the specified length, the control unit 32 determines that the chip 11 is attracted and held by the Bernoulli pads 18a and 18b, and fixes the flow rate of the air supplied from the electric air pressure regulator 30 (air flow rate fixing step S30).

[0056] In this embodiment, the control unit 32 determines that the wafer 11 is attracted and held by the Bernoulli pads 18a and 18b when the distance A becomes a predetermined length, and fixes the airflow. Therefore, it is possible to avoid excessive increase in the impact force of air on the wafer 11, and thus it is possible to attract and hold the wafer 11 appropriately with an attractive force that does not damage the wafer 11.

[0057] Furthermore, even when the distance A is at the specified length, the chip 11 is held in a state of attraction with minimal force, and there is still a possibility that the chip 11 may fall from the hand 16 for some reason. However, when the airflow is excessively increased, there is still a possibility that the chip 11 may break.

[0058] Specifically, when the airflow is increased, the air impact force increases, causing the wafer 11 to vibrate in a manner that undulates along its thickness direction under the influence of airflow. The amplitude of this vibration increases with the increase in air impact force, which may lead to breakage of the wafer 11.

[0059] Therefore, in the second embodiment, an electrostatic capacitive vibration sensor is used as sensor 22. Furthermore, the control unit 32 monitors the amplitude of the vibration of the wafer 11, which gradually increases with the increase in airflow.

[0060] In the second embodiment, it is also in accordance with Figure 4 The same steps are used to attract and hold the chip 11. First, the linkage mechanism 4 is activated so that one surface 16d of the hand 16 is opposite to a chip 11 stored in the box 24.

[0061] Next, the input signal to the electric pneumatic regulator 30 is controlled to gradually increase the air flow rate supplied from the electric pneumatic regulator 30 to the Bernoulli pads 18a and 18b from zero (air flow rate increase step S10).

[0062] The control unit 32 monitors the distance A in real time via the sensor 22, thereby monitoring the amplitude of the vibration of the wafer 11. When the amplitude does not reach the predetermined amount, the control unit 32 determines that the wafer 11 is not attracted and held ("No" in S20) and continues to increase the air flow.

[0063] As the air flow rate increases, the wafer 11 rises and is held in place by the Bernoulli pads 18a and 18b. At this time, the air flow rate is the same as that fixed in the air flow rate fixing step S30 of the first embodiment. However, at this stage, almost no vibration occurs, and even if vibration does occur, it is not to the extent that it would damage the wafer 11.

[0064] Next, the airflow is increased, and when the amplitude is detected by sensor 22 to be a predetermined amount, the control unit 32 determines that the wafer 11 is attracted and held ("yes" in S20). The predetermined amplitude varies depending on the diameter, thickness, material, etc. of the wafer 11.

[0065] For example, in the case where wafer 11 is a silicon wafer with a diameter of 300 mm, a thickness of 100 μm for the outer periphery corresponding to the remaining outer periphery region, and a thickness of 30 μm for the portion corresponding to the device region, the specified amplitude is 1.0 μm.

[0066] When the amplitude of the wafer 11 reaches a predetermined amount, the control unit 32 determines that the wafer 11 is properly attracted and held by the Bernoulli pads 18a and 18b, and fixes the air flow rate (air flow rate fixing step S30).

[0067] In this embodiment, compared to the first embodiment, the wafer 11 can be held with a stronger attraction force, and the wafer 11 can be prevented from breaking due to excessive vibration. Furthermore, the structure and method of the above embodiment can be appropriately modified and implemented as long as they do not depart from the scope of the present invention.

Claims

1. A holding mechanism having a Bernoulli pad that holds the plate by means of negative pressure generated by blowing air onto the plate, characterized in that, The retaining mechanism has: The Bernoulli pad is fitted onto the hand; A sensor, which is disposed on the hand, detects whether the plate-like object is attracted and held by the Bernoulli pad; A lateral movement limiting part is disposed on the hand and restricts the lateral movement of the plate-shaped object; The pipe connects to the Bernoulli mat, which is an air source that supplies air to the Bernoulli mat. A regulating valve, disposed on the pipe, regulates the flow rate of air supplied to the Bernoulli pad; and The control unit controls the operation of the regulating valve. The control unit gradually increases the airflow supplied from the regulating valve to the Bernoulli pad, and fixes the airflow when the sensor detects that the plate is under negative pressure and is attracted and held by the Bernoulli pad.

2. The retaining mechanism according to claim 1, characterized in that, This sensor is a proximity sensor. When the sensor detects that the distance between the sensor and the plate is a predetermined length, the control unit determines that the plate is attracted and held by the Bernoulli pad, and fixes the flow rate of air supplied from the adjustment valve to the Bernoulli pad.

3. The retaining mechanism according to claim 1, characterized in that, This sensor is a vibration sensor. When the sensor detects that the amplitude of the vibration of the plate, which gradually increases with the increase of air flow, reaches a predetermined amount, the control unit determines that the plate is attracted and held by the Bernoulli pad, and fixes the flow rate of air supplied from the regulating valve to the Bernoulli pad.

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