Die bonding apparatus and die positioning method using the die bonding apparatus

Abstract

The invention relates to a die positioning method using a die bonding apparatus, the apparatus comprising: a carriage; a linear encoder includes an encoder scale and first and second encoder heads. The carriage includes a joint head and a camera. A central axis of the bonding head and an optical axis of the camera are a first distance from each other along the traveling direction. The first and second encoder heads are at a second distance from each other along the direction of travel, the second distance corresponding to the first distance and an offset corresponding to an alignment error between the first and second encoder heads and the central axis of the bond head and the optical axis of the camera, respectively. Comprising: a) finding a target position for positioning the die, b) measuring or recording an alignment error between the camera optical axis and the target position, c) recording a difference between the first and second distances, d) recording the positioning of the carriage, e) aligning the bond head with the target position: i) outputs of the first and second encoder heads; ii) the recorded difference; and iii) optionally aligning the error, and f) placing the die at the target location.

Description

Technical Field

[0001] This invention relates to the semiconductor industry, and more particularly to a die bonding method for accurately positioning a die prior to bonding. The invention also relates to a die bonding apparatus for performing the die bonding method. The die bonding apparatus and method are particularly suitable for hybrid bonding applications requiring high-accuracy die placement with placement errors as low as ±50 nm. Background Technology

[0002] Die bonding is widely used to attach or bond semiconductor chips (also known as dies) to a substrate or package. Various techniques can be used to perform die bonding, including wiring bonding, flip-chip bonding, and adhesive bonding. Die bonding plays a crucial role in creating the electrical connections necessary for the functionality of semiconductor devices. Precise die positioning is a fundamental aspect of semiconductor manufacturing to achieve optimal electrical performance, functionality, reliability, and consistency in the final semiconductor device.

[0003] As in Figures 1 to 1c As shown, a conventional die bonding system includes a carriage C, which comprises a bonding head BH and a downward-facing camera DLC to measure the positioning of pads on the PCB for increased die placement accuracy. Figure 1 As shown, the downward-facing camera DLC and the connector BH are attached to the carriage C at a fixed distance D. The carriage C is slidably connected to a track to move along the encoder scale ES. The movement of the carriage C is measured using a single encoder head EH mounted on the carriage C, which is arranged to move along and above the encoder scale ES. The distance D between the downward-facing camera DLC and the connector BH is measured using the encoder and the upward-facing camera ULC, while the carriage C is moved to search for the central axis of the connector BH and the optical axis of the camera DLC. The downward-facing camera DLC is used to measure the exact location on the PCB where the die must be bonded to the pads. Figure 1a As shown, the camera DLC measures the alignment error ΔX between the optical axes of the target position TP and the downward-looking camera DLC. The carriage C is then moved a distance D+ΔX, so that the coupling head BH is above the target position to place the die, as shown in... Figure 1b and Figure 1c As shown in the image.

[0004] The placement accuracy of these systems is not optimal because varying placement errors can occur. In particular, the heat generated by the motor causes thermal expansion of the encoder scale at D+ΔX, as well as thermal expansion of the carriage C, which directly affects the distance D between the coupling and the camera. Scale engraving defects at D+ΔX also negatively impact the placement accuracy of these systems.

[0005] Additionally, in hybrid bonding applications, dies are stacked one on top of another in the package using small copper-to-copper connections, thus requiring placement accuracy of the dies in the range of ±50nm placement error.

[0006] Positioning systems comprising two encoder heads for compensating for measurement errors caused by thermal expansion of the encoder scale are also known. For example, EP2636991A1 relates to a measuring machine provided with a system for compensating for measurement errors caused by thermal expansion of the scale of a linear transducer. The encoder heads are used to calculate a scaling factor based on the distance between the two encoder heads and their respective readings to compensate for the thermal expansion of the scale.

[0007] DE19919042A1 discloses a thermally compensated positioning system comprising a scale support and a carriage arranged to move along the scale, and two encoder heads spaced apart from each other by a predetermined distance along the direction of travel of the carriage. Both encoder heads are configured to detect a reference mark and feed two signals associated with the reference mark to an evaluation unit to compensate for thermal expansion of the encoder scale by using the relative distance between the two encoder heads that changes with temperature.

[0008] Other thermally compensated positioning systems, including those with two encoder heads, are disclosed, for example, in DE102021118091A1, DE102021118092A1, EP2527797A1, and EP3982088A1. Generally, these positioning systems rely on multiple sensing units on the same scale to compensate for temperature or calibrate the scale. Scale mapping is typically used for thermal expansion compensation, but it is cumbersome and time-consuming. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide a die bonding device and a die positioning method for accurately positioning the die before bonding, wherein the die bonding device and the die positioning method avoid the above limitations.

[0010] More specifically, the object of the present invention is to provide a die bonding device for highly accurate positioning of dies with a placement error range as low as ±50 nm.

[0011] Another object of the present invention is to provide a die positioning method, wherein the die placement is insensitive to thermal expansion, particularly of the encoder scale.

[0012] Another object of the present invention is to provide a die positioning method, wherein the die placement is insensitive to scale engraving defects.

[0013] These objectives are achieved, in particular, by a die-joining device comprising: a linear motor; a carriage arranged to be driven by the linear motor along a direction of travel; a linear encoder including an encoder scale extending along the direction of travel of the carriage, at least a first encoder head and a second encoder head mounted on the carriage; and a controller arranged to move the carriage as a function of values ​​read by the respective first and second encoder heads to align the join head with a target position. The carriage includes a join head configured to pick up a die and a camera configured to detect the target position for positioning the die and for measuring the alignment error between the camera's optical axis and the target position. The central axis of the join head and the optical axis of the camera are separated from each other by a first distance along the direction of travel. The first and second encoder heads are separated from each other by a second distance along the direction of travel, the second distance corresponding to the first distance and to the offsets corresponding to the alignment errors between the first and second encoder heads and the central axis of the join head and the optical axis of the camera, respectively.

[0014] In this embodiment, the first encoder head and the second encoder head are aligned with the central axis of the coupling head and the optical axis of the camera, respectively, and have alignment error.

[0015] In an embodiment, when carried by the connector for positioning the die at the target location, the central axis of the connector intersects the center of the die.

[0016] In one embodiment, the die engagement device further includes a crossbeam and two additional motion axes slidably connected to and orthogonally extending from the crossbeam. A carriage is slidably mounted along the crossbeam. The linear encoder is a 1Dplus encoder, comprising a linear scale with an incremental track and an additional track, a first set of encoder heads corresponding to the carriage engagement head, and a second set of encoder heads corresponding to the camera arrangement. Each set of encoder heads includes a Y encoder head arranged to scan the incremental track and at least one X encoder head arranged to scan the additional track for positioning correction of the crossbeam using the additional motion axes.

[0017] In one embodiment, each encoder head set includes two X encoder heads for angle correction of the coupling head and camera using an additional motion axis.

[0018] In one embodiment, the X encoder heads of the first set of encoder heads and the second set of encoder heads are arranged on both sides of the respective coupling head and the camera.

[0019] In this embodiment, the Y encoder heads of the first set of encoder heads and the second set of encoder heads are aligned with the central axis of the coupling head and the optical axis of the camera, respectively, and have alignment error.

[0020] Another aspect of the present invention relates to a die positioning method using a die bonding device according to any of the embodiments described above, wherein the method includes the following steps:

[0021] a) Use the camera on the carriage to find the target position for positioning the tube core.

[0022] b) Measure or record the alignment error between the camera optical axis and the target position.

[0023] c) Record the difference between the first distance and the second distance.

[0024] d) Record the carriage positioning using the first encoder head.

[0025] e) Aligning the engagement head with the target position by moving the carriage as a function of: i) the outputs of the first encoder head and the second encoder head, ii) the recorded difference, and optionally the alignment error, and

[0026] f) Actuate the connector in the Z direction to place the die at the target location.

[0027] In this embodiment, the die positioning method includes the following steps:

[0028] Based on camera feedback, micro-alignment is performed to minimize alignment error, preferably below 10 nm.

[0029] The carriage is moved to position the second encoder head at the location recorded by the first encoder head, with an offset corresponding to the difference between the recorded first and second distances.

[0030] In this embodiment, the die positioning method includes the following steps:

[0031] - Record the alignment error between the camera optical axis and the target position, and

[0032] - The moving carriage is used to position the second encoder head at the location recorded by the first encoder head by combining the difference between the recorded first and second distances and the offset of the alignment error.

[0033] In an embodiment, the die bonding device further includes an upward-viewing camera positioned below the target location and oriented towards the carriage. The die positioning method further includes a calibration step performed prior to initiating die placement at the target location. The calibration step comprises: driving the carriage to move the camera and bonding head above the upward-viewing camera, enabling the upward-viewing camera to measure a first distance; and further driving the carriage in the same direction, causing a first encoder head and a second encoder head to move across a reference mark on an encoder scale to measure a second distance, in order to determine an encoder head alignment error as a function of the measured first distance.

[0034] In this embodiment, the offset between the central axis of the connector and the center of the mandrel carried by the connector is measured using an upward-viewing camera. This offset is used to correct the carriage positioning so that the mandrel can be accurately positioned at the target location independently of the magnitude of the offset.

[0035] Another aspect of the present invention relates to a die positioning method using a die bonding device, wherein the method includes the following steps:

[0036] - Use a camera to locate the target position for positioning the die.

[0037] - Record the misalignment between the camera's optical axis and the target position.

[0038] - The carriage is moved as a function of the signal outputs acquired by the corresponding first and second encoder heads to align the engagement head with the target position along the XY direction and about the Z-axis, and

[0039] - Actuate the die connector in the Z direction to place the die at the target location. Attached Figure Description

[0040] The invention will be better understood with the aid of embodiments given by way of example and described by way of illustration, in which:

[0041] - Figure 1 A schematic diagram of a die-joining device according to the prior art is shown;

[0042] - Figures 1a to 1c It shows how to use Figure 1 The die-joining device moves the die to the target location in a sequence of motion.

[0043] - Figure 2 A schematic diagram of a die-joining device according to an embodiment is shown.

[0044] - Figures 2a to 2c An example of using is shown. Figure 2The movement sequence of a die-jointing device for placing the die at the target location.

[0045] - Figure 3 A schematic diagram of a coupling device according to another embodiment is shown, and

[0046] - Figure 4 A schematic diagram of a die-joining device according to a further embodiment is shown. Detailed Implementation

[0047] Reference Figure 2 In the embodiment illustrated, the die-joining device 10 includes a linear motor (not shown) and a carriage 12 arranged to be driven by the motor along the direction of travel. The carriage 12 includes components configured to pick up the die 50 ( Figure 2a The device includes a connector 14 and a first camera 16 configured to detect a target position 30 for positioning the die 50. The camera 16 and the connector 14 are mounted on a carriage 12, wherein there is a first distance D1 between the optical axis of the camera 16 and the central axis of the connector 14 along the travel direction of the carriage 12.

[0048] The die engagement device 10 further includes a linear encoder having a scale 20 extending along the travel direction of the carriage 12, a first encoder head 22a and a second encoder head 22b mounted on the carriage 12, and a controller configured to move the carriage 12 as a function of the values ​​read by the respective first encoder head 22a and second encoder head 22b to align the die 50 with the target position 30. (As in...) Figure 2 As shown, the first encoder head 22a and the second encoder head 22b are separated from each other by a second distance D2 along the travel direction of the carriage 12.

[0049] In a preferred embodiment, the two encoder heads 22a, 22b are positioned as close as possible to each other in a manner aligned with the corresponding camera optical axis and the central axis of the connector. However, there is always an encoder head alignment error δ with respect to the corresponding camera 16 and connector 14, which must be taken into account to position the die with the highest accuracy. Therefore, the second distance D2 between the two encoder heads 22a, 22b corresponds to the first distance D1 and the offset corresponding to the encoder head alignment error δ, as shown in... Figure 2 As shown in the diagram.

[0050] As explained above, linear encoders are sensitive to thermal expansion, particularly thermal expansion caused by heat generated by the motor. When the engagement device 10 is in operation, the encoder scale 20 generally expands in its longitudinal direction, causing measurement errors on the scale. The initial distance D1 between the optical axis of the camera 16 and the central axis of the engagement head 14 may also vary due to the thermal expansion of the carriage 12. The scale 20 may also have engraving defects. All these parameters must be considered to place the die 50 at the target position 30 with the highest accuracy.

[0051] Advantageously, die placement performed by the die positioning method described later is insensitive to these parameters.

[0052] A calibration step is required before initiating die placement to measure the first distance D1 and the second distance D2, and to determine the encoder head alignment error δ.

[0053] In this respect, the die bonding device 10 further includes a second camera 18, as in Figure 2a As shown, the second camera 18 is positioned below the target position 30 and oriented towards the carriage 12. The carriage 12 is driven to move the first camera 16 and the engagement head 14 above the second camera 18, enabling the second camera 18 to measure a first distance D1. The carriage 12 is then further driven in the same direction, causing the first encoder head 22a and the second encoder head 22b to move across the reference mark "0" of the encoder scale 20 to measure a second distance D2 in order to determine the encoder head alignment error δ as a function of the measured first distance D1.

[0054] Reference Figure 2a Once the calibration steps are completed, the die positioning method includes the following: driving the carriage 12 to align the optical axis of the first camera 16 with the target position 30. More specifically, the camera 16 measures the alignment error ΔX between the camera optical axis and the target position 30. The signal output of the camera 16 is sent to the motor controller to drive the motor to perform several micro-alignments to minimize the alignment error ΔX as much as possible, preferably below 10 nm.

[0055] Then, the first encoder head 22a reads the positioning P1 on the encoder scale 20. The motor controller then drives the motor as a function of the signal outputs of the first encoder head 22a and the second encoder head 22b and moves the carriage 12 according to the encoder head alignment error δ, such that the second encoder head 22b is moved to the positioning P1-δ. Thus, the central axis of the coupling head 14 is aligned with the target position 30 with an accuracy of less than 10 nm. The coupling head 14 is then actuated in the Z direction to engage the die 50 on top of the other die with high accuracy.

[0056] Therefore, it is readily apparent that any thermal expansion and / or any engraving defects of the encoder ruler 20 have no effect on the placement accuracy of the die 50, because the discrete position P1 to which the second encoder head 22b is brought remains at a fixed point regardless of the thermal expansion / engraving defect parameters. This also highlights the need to minimize the encoder head alignment error δ so that the target positioning P1-δ of the second encoder head 22b is as close as possible to the positioning P1.

[0057] In another embodiment, the die positioning method includes aligning the engagement head 14 with the target position 30 without performing the camera axis micro-alignment steps described above. Alternatively, the alignment error ΔX between the camera axis and the target position 30 is first recorded, and the motor controller, as a function of the signal outputs of the corresponding first encoder head 22a and second encoder head 22b, drives the carriage 12 according to the encoder head alignment error δ, such that the second encoder 22b is moved to the position P1-δ+ΔX. The die positioning method according to this embodiment has the advantage of being faster, at the cost of accuracy. In fact, the accuracy achieved is a local accuracy on ΔX, meaning that any thermal expansion and / or any scale engraving errors occurring on ΔX will directly affect the die placement accuracy.

[0058] according to Figure 3 In another embodiment schematically illustrated, camera 16 and connector 14 are mounted on carriage 12, wherein there is a distance D1 between the camera optical axis and the connector central axis along the travel direction of carriage 12. A first encoder head 22a and a second encoder head 22b are mounted on carriage 12 such that they are offset along the travel direction with respect to the camera optical axis and the connector central axis. However, the distance D2 between encoder heads 22a and 22b remains the same as the first distance D1, with an offset corresponding to the alignment error δ.

[0059] However, according to this embodiment, considering that the portion of the carriage 12 within distance D1 may have slightly different behavior in terms of thermal expansion when subjected to the heat of the motor compared to the portion within distance D2, the placement of the core 50 at the target position 30 may not be entirely accurate.

[0060] In a preferred embodiment, an upward-viewing camera 18 is used to measure the offset between the central axis of the connector 14 and the center of the die 50 carried by the connector 14. This offset is used to position the die at the target location 30. The measured offset is then fed to the motor controller to correct the positioning of the carriage 12. This ensures accurate positioning of the die 50 even if its center is not aligned with the central axis of the connector.

[0061] according to Figure 4In another embodiment schematically illustrated, the die coupling device 10 includes: a Y-beam 130 slidably connected to two motion axes 140 in the X direction; and a carriage 12 mounted to move along the Y-beam and including a coupling head 14, a camera 16, and two sets of encoder heads arranged to read a 1Dplus scale 120, characterized by an incremental track 120a along the Y direction and an additional track 120b providing information required for compensation and angle correction in the vertical direction.

[0062] The first set of encoder heads includes a Y encoder head 122a arranged on the incremental track 120a of the 1Dplus scale 120, and two X encoder heads 122b and 122c arranged on the auxiliary track 120b on both sides of the coupling head 14. The second set of encoder heads includes a Y encoder head 124a arranged on the incremental track 120a of the 1Dplus scale 120, and two X encoder heads 124b and 124c arranged on the auxiliary track 120b on both sides of the camera 16.

[0063] Using the corresponding first group Y encoder head 122a and second group Y encoder head 124a according to... Figures 2 to 2c The die positioning method described in connection with the embodiments performs alignment of the engagement head 14 along the Y direction by moving the carriage 12. Two X encoder heads 122b, 122c, 124b, 124c are arranged to use the motion axis 140 to compensate for alignment errors in the X direction and angular errors in the Rz direction.

[0064] While the invention has been illustrated and described in detail in the accompanying drawings and foregoing description, such illustrations and descriptions are to be regarded as illustrative or exemplary and not restrictive. It will be understood that changes and modifications can be made by those skilled in the art within the scope of the appended claims. For example, the die positioning method using a die-joining device can be adapted for a 6-DOF positioning system with multiple encoders.

[0065] Reference List

[0066] die bonding device 10

[0067] Carriage 12

[0068] Connector 14

[0069] First Camera 16

[0070] Second camera 18

[0071] Encoder scale 20

[0072] First encoder head 22a and second encoder head 22b

[0073] 1Dplus encoder scale 120

[0074] Incremental orbit 120a

[0075] Additional track 120b

[0076] First encoder component

[0077] Y encoder head 122a

[0078] Two X encoder heads 122b and 122c

[0079] Second encoder component

[0080] Y-code head 124a

[0081] Two X encoder heads, 124b and 124c

[0082] Y-beam 130

[0083] 140 motion axis

[0084] Target location 30

[0085] Camera alignment error ΔX at the target position

[0086] The encoder head alignment error δ with the corresponding camera and connector

[0087] Distance D1 between camera and connector

[0088] Distance D2 between the two encoder heads

[0089] Core 50.

Claims

1. A die bonding device (10), comprising: Linear motor; A carriage (12) arranged to be driven by a linear motor along the direction of travel includes a coupling head (14) configured to pick up a die (50) and a camera (16) configured to detect a target position (30) for positioning the die (50) and for measuring the alignment error (ΔX) between the optical axis of the camera (16) and the target position (30), wherein the central axis of the coupling head (14) and the optical axis of the camera (16) are separated from each other by a first distance (D1) along the direction of travel. The die coupling device (10) also includes a linear encoder including an encoder scale (20) extending along the direction of travel of the carriage (12), and at least one [unclear text] mounted on the carriage (12). A first encoder head and a second encoder head (22a, 22b; 122a, 122b, 122c, 124a, 124b, 124c), and a controller arranged to move the carriage (12) as a function of values ​​read by the respective first encoder head and second encoder head (22a, 22b) to align the engagement head (50) with the target position (30), wherein the first encoder head and the second encoder head are a second distance (D2) apart from each other along the direction of travel, the second distance (D2) corresponding to the first distance (D1) and the alignment error (δ) between the first encoder head and the second encoder head and the central axis of the engagement head (14) and the optical axis of the camera (16), respectively.

2. The die bonding device (10) according to claim 1, wherein the first encoder head and the second encoder head (22a, 22b) are respectively aligned with the central axis of the bonding head (14) and the optical axis of the camera (16), and have an alignment error (δ).

3. The die bonding device (10) according to any of the preceding claims, wherein when carried by the bonding head for positioning the die at the target position (30), the central axis of the bonding head (14) intersects the center of the die (50).

4. The core engagement device (10) according to any of the preceding claims further includes a crossbeam (130) and two motion shafts (140) slidably connected to and orthogonally extending from the crossbeam (130), wherein the carriage (12) is slidably mounted along the crossbeam (130), and wherein the linear encoder is a 1Dplus encoder, including a linear scale (120) having an incremental track (120a) and an additional track (120b), and a first set of encoder heads and a second set of encoder heads arranged corresponding to the engagement head (14) of the carriage and the camera (16), each set of encoder heads including a Y encoder head (122a, 124a) arranged to scan the incremental track (120a) and at least one X encoder head (122b, 122c; 124b, 124c) arranged to scan the additional track (120b) for positioning correction of the crossbeam (130) using the motion shafts (140).

5. The die bonding device (10) according to the preceding claim, wherein each set of encoder heads includes two X encoder heads (122b, 122c; 124b, 124c) for angle correction (RZ) of the bonding head (14) and the camera (16).

6. The die bonding device (10) according to the preceding claim, wherein the X encoder heads (122b, 122c; 124b, 124c) of the first set of encoder heads and the second set of encoder heads are arranged on both sides of the respective bonding head (14) and the camera (16).

7. The die bonding device (10) according to any one of claims 4 to 6, wherein the Y encoder heads (122a, 124a) of the first set of encoder heads and the second set of encoder heads are aligned with the central axis of the bonding head (14) and the optical axis of the camera (16), respectively, having an alignment error (δ).

8. A die positioning method using the die bonding device (10) according to any one of the preceding claims, wherein the method comprises the following steps: a) Using the camera (16) on the carriage (12), find the target position (30) for positioning the core (50), b) Measure or record the alignment error (ΔX) between the camera optical axis and the target position (30), c) Record the difference (δ) between the first distance (D1) and the second distance (D2). d) Record the positioning (P1) of the carriage (12) using the first encoder head (22a; 122a). e) Aligning the joint (14) with the target position (30) by moving the carriage (12) as a function of: i) the outputs of the first encoder head and the second encoder head (22a, 22b; 122a, 124a); ii) the recorded difference (δ); and iii) optionally the alignment error (ΔX), and f) Actuate the connector (14) in the Z direction to place the die at the target position (30).

9. The die positioning method according to the preceding claim comprises the following steps: Based on feedback from the camera (16), micro-alignment is performed to minimize the alignment error (ΔX), preferably less than 10 nm. The movable carriage (12) is used to position the second encoder head (22b; 124a) at the position recorded by the first encoder head (22a, 122a) with an offset corresponding to the recorded difference (P1-δ).

10. The die positioning method according to claim 8, comprising the following steps: - Record the alignment error (ΔX) between the camera optical axis and the target position (30), and - The moving carriage (12) positions the second encoder head (22b; 124a) at the position recorded by the first encoder head (22a, 122a) by combining the recorded difference (δ) and alignment error (ΔX) with an offset.

11. The die positioning method according to any one of claims 8 to 10, wherein the die joining device (10) further includes an upward-viewing camera (18) positioned below the target position (30) and oriented toward the carriage (12), and wherein a calibration step is performed prior to initiating die placement, the calibration step comprising: driving the carriage (12) to move the camera (16) and the joining head (14) above the upward-viewing camera (18) such that the latter can measure a first distance (D1); further driving the carriage (12) in the same direction such that a first encoder head and a second encoder head (22a, 22b) move across a reference mark ("0") of the encoder scale (20) to measure a second distance (D2) in order to determine an encoder head alignment error (δ) as a function of the measured first distance (D1).

12. The die positioning method according to the preceding claim, wherein an upward-viewing camera (18) is used to measure the offset between the central axis of the joint (14) and the center of the die (50) carried by the joint (14), and wherein the offset is used to correct the positioning of the carriage (12) for accurately positioning the die (50) at the target position (30) independently of the magnitude of the offset.

13. A die positioning method using the die bonding device (10) according to any one of claims 4 to 7, wherein the method comprises the following steps: -Use the camera (16) to find the target location for locating the die. - Record the misalignment between the camera's optical axis and the target position (30). -The carriage (12) is moved as a function of the signal outputs obtained by the corresponding first and second encoder heads to align the engagement head (14) with the target position (30) along the XY direction and about the Z-axis (Rz), and - Actuate the die connector (14) in the Z direction to place the die at the target location.

Images