PICK-AND-PLACE APPARATUS AND METHOD

Abstract

Aspects of the present disclosure relate to a pick-and-place apparatus that is configured to cause components to be placed on a substrate in a number of passes, and during each pass, components among a plurality of components are placed on the substrate in a respective placement pattern among a collection of interleaved placement patterns.

Claims

1. A pick-and-place apparatus, comprising: a source supporting unit configured to hold a carrier that is provided with and/or supports a plurality of components; a target supporting unit configured to hold a substrate; a first drive unit for driving the source supporting unit; a second drive unit for driving the target supporting unit; a transport unit for collecting a component from the carrier and for placing the collected component on the substrate; and a controller for controlling the first drive unit, the second drive unit, and the transport unit; wherein the controller is configured to cause the components to be placed on the substrate in a number of passes, and during each pass, components among the plurality of components are placed on the substrate in a respective placement pattern among a collection of interleaved placement patterns; wherein the placement patterns are uniform placement patterns, wherein each placement pattern comprises a repetition of a unit cell, the unit cell comprising second positions to which that placement pattern corresponds, and empty positions representing second positions to which other placement patterns correspond, the unit cell having a first size in a first direction and a second size in a second direction different from the first direction, wherein each pair of unit cells has a distance between each pair that in the first direction equals an integer times the first size, and wherein each pair of unit cells has a distance between each pair that in the second direction equals an integer times the second size.

2. The pick-and-place apparatus according to claim 1, wherein the carrier comprises a foil or film, and/or wherein the plurality of components comprises semiconductor dies or packaged semiconductor dies arranged on the carrier, and/or wherein the plurality of components is formed by a diced semiconductor wafer arranged on the carrier, and/or wherein the plurality of components comprises light-emitting diodes.

3. The pick-and-place apparatus according to claim 1, wherein the components are arranged in a plurality of first rows and first columns of first positions on the carrier at which positions the components are to be collected, and wherein the substrate comprises a plurality of second rows and second columns of second positions on the substrate at which positions the components are to be placed.

4. The pick-and-place apparatus according to claim 1, wherein the respective placement patterns are substantially translated copies of each other.

5. The pick-and-place apparatus according to claim 1, wherein each placement pattern covers substantially the entire substrate.

6. The pick-and-place apparatus according to claim 1, wherein the controller is configured to process the unit cells corresponding to the relevant placement pattern on a line-by-line basis when performing one pass, wherein each line comprises a plurality of unit cells that are adjacently arranged in the first direction; wherein the pick-and-place apparatus is configured to, for each unit cell, introduce one or more offsets in the second direction when processing a line of unit cells.

7. The pick-and-place apparatus according to claim 1, wherein the pick-and-place apparatus comprises a pattern determination unit that is configured to: receive a wafer map that indicates the performance and/or characteristics of the components on the carrier that are to be placed on the substrate; determine, for each combination of collect and placement patterns among a plurality of the combinations: a value of a uniformity metric that describes the uniformity of the performance and/or characteristics over the substrate if the components are pick-and-placed on the substrate on the basis of each predefined combination; a value of a throughput metric that describes the throughput of the pick-and-place apparatus when using the predefined combination; a value of a general metric based on a weighed combination of the value of the uniformity metric and the value of the throughput metric; determine an optimal combination of collect and placement patterns among the plurality of combination using the determined values of the general metric; and provide the optimal combination of collect and placement patterns to the controller; wherein the pattern determination unit is comprised of and/or embodied by the controller.

8. The pick-and-place apparatus according to claim 1, wherein the transport unit is configured to collect each component from the carrier at a same collect position in space, and wherein the controller is configured to control the first drive unit for moving the source supporting unit relative to the collect position in space to collect the components from the carrier; and/or wherein the transport unit is configured to release each collected component on the substrate carrier at a same release position in space, and wherein the controller is configured to control the second drive unit for moving the moveable substrate table relative to the release position in space to release the components on the substrate.

9. The pick-and-place apparatus according to claim 2, wherein the components are arranged in a plurality of first rows and first columns of first positions on the carrier at which positions the components are to be collected, and wherein the substrate comprises a plurality of second rows and second columns of second positions on the substrate at which positions the components are to be placed.

10. The pick-and-place apparatus according to claim 2, wherein the respective placement patterns are substantially translated copies of each other.

11. The pick-and-place apparatus according to claim 2, wherein each placement pattern covers substantially the entire substrate.

12. The pick-and-place apparatus according to claim 2, wherein the controller is configured to process the unit cells corresponding to the relevant placement pattern on a line-by-line basis when performing one pass, and process the unit cells corresponding to the relevant placement pattern on a line-by-line basis, wherein each line comprises a plurality of unit cells that are adjacently arranged in the first direction; and wherein the pick-and-place apparatus is configured to, for each unit cell, introduce one or more offsets in the second direction when processing a line of unit cells.

13. The pick-and-place apparatus according to claim 2, wherein the pick-and-place apparatus comprises a pattern determination unit that is configured to: receive a wafer map that indicates the performance and/or characteristics of the components on the carrier that are to be placed on the substrate; determine, for each combination of collect and placement patterns among a plurality of the combinations: a value of a uniformity metric that describes the uniformity of the performance and/or characteristics over the substrate if the components are pick-and-placed on the substrate on the basis of each predefined combination; a value of a throughput metric that describes the throughput of the pick-and-place apparatus when using the predefined combination; a value of a general metric based on a weighed combination of the value of the uniformity metric and the value of the throughput metric; determine an optimal combination of collect and placement patterns among the plurality of combination using the determined values of the general metric; and provide the optimal combination of collect and placement patterns to the controller; wherein the pattern determination unit is comprised of and/or embodied by the controller.

14. The pick-and-place apparatus according to claim 3, wherein the controller is configured to cause the components to be collected from the carrier in a number of passes, wherein during each pass, components among the plurality of components are collected from the carrier in accordance with a respective collect pattern among a collection of interleaved collect patterns.

15. The pick-and-place apparatus according to claim 14, wherein for each collect pattern and for at least one direction among a direction corresponding to the first rows and a direction corresponding to the first columns, first positions corresponding to that collect pattern are separated in the at least one direction by one or more first positions corresponding to one or more of the other collect patterns.

16. A method for collecting components from a carrier that is arranged on a source supporting unit and for placing the collected components on a substrate that is arranged on a target supporting unit, wherein the placing the collected components comprises placing the components on the substrate in a number of passes, wherein during each pass, components among the plurality of components are placed on the substrate in a respective placement pattern among a collection of interleaved placement patterns; wherein the placement patterns are uniform placement patterns, wherein each placement pattern comprises a repetition of a unit cell, the unit cell comprising second positions to which that placement pattern corresponds, and empty positions representing second positions to which other placement patterns correspond, the unit cell having a first size in a first direction and a second size in a second direction different from the first direction, wherein each pair of unit cells has a distance between each pair that in the first direction equals an integer times the first size, and wherein each pair of unit cells has a distance between each pair that in the second direction equals an integer times the second size.

17. The method according to claim 16, wherein the components are arranged in a plurality of first rows and first columns of first positions on the carrier at which positions the components are to be collected, wherein the substrate comprises a plurality of second rows and second columns of second positions on the substrate at which positions the components are to be placed, and wherein for each placement pattern and for at least one direction among a direction corresponding to the second rows and a direction corresponding to the second columns, second positions corresponding to that placement pattern are separated in the at least one direction by one or more second positions corresponding to one or more of the other placement patterns.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0050] So that the manner in which the features of the present disclosure can be understood in detail, a more particular description is made with reference to embodiments, some of which are illustrated in the appended figures. It is to be noted, however, that the appended figures illustrate only typical embodiments and are therefore not to be considered limiting of its scope. The figures are for facilitating an understanding of the disclosure and thus are not necessarily drawn to scale. Advantages of the subject matter claimed will become apparent to those skilled in the art upon reading this description in conjunction with the accompanying figures, in which like reference numerals have been used to designate like elements, and in which:

[0051] FIG. 1 illustrates a known pick-and-place apparatus.

[0052] FIG. 2 illustrates a wafer map of a semiconductor wafer and two examples of display panels that can be obtained using semiconductor dies from that semiconductor wafer.

[0053] FIG. 3 illustrates four examples of placement patterns with their corresponding unit cells in which offset within unit cells is not used.

[0054] FIG. 4 illustrates an example of a placement pattern with its corresponding unit cell in which offset within the unit cell is used.

[0055] FIG. 5 illustrates the computation of a local average for a given wafer map.

DETAILED DESCRIPTION

[0056] FIG. 2 illustrates an example of a wafer map 200. In this figure, the grey color at a given position indicates a value that is representative for a parameter describing the behavior of the semiconductor die at that position. For example, the grey color could indicate the brightness or color temperature associated with a light-emitting diode at that position.

[0057] FIG. 2 further illustrates two examples of display panels 300A, 300B that can be realized using the LEDs from the wafer corresponding to wafer map 200. Display panels 300A, 300B may each comprise a large number, e.g. 10.sup.4 to 10.sup.6, of light-emitting diode semiconductor dies.

[0058] The figures illustrating display panels 300A, 300B illustrate the color uniformity of the light emitted by display panels 300A, 300B. The difference between display panels 300A, 300B is that display panel 300A has been constructed using a known serpentine-based pick-and-place method and display panel 300B has been constructed using a pick-and-place method in accordance with an aspect of the present disclosure. As can be verified, the uniformity of display panel 300B as perceived by a user is better than that of display panel 300A.

[0059] FIG. 3 illustrates several examples of placement patterns 400A, 400B, 400C in accordance with an aspect of the present disclosure. Each placement pattern comprises a regular repetition of a unit cell 401A, 401B, 401C in a row direction r and column direction c. These unit cells are depicted below their respective placement patterns.

[0060] Placement patterns 400A, 400B, 400C are arranged over substrate 102A. An example thereof is shown for placement pattern 400A. For each placement pattern, a black box indicates that during the processing of that placement pattern, i.e. during a single pass, a component is to be arranged on substrate 102A at that position, whereas a white box indicates that no components needs to be arranged at that position. The occupancy level of each unit cell, i.e. the number of black boxes divided by the total number of boxes, determines the number of passes required to completely fill substrate 102A. For example, for unit cell 401B, the occupancy level equals , requiring 4 passes to completely fill substrate 102A. Typically, the number of required passes equals the reciprocal of the occupancy level rounded off to the nearest larger integer.

[0061] By interleaving two placement patterns similar to placement pattern 400A, it can be ensured that substrate 102A is entirely filled with components. This is shown on the right in FIG. 3. Here, a first placement pattern 400A is arranged over substrate 102A for arranging components during a first pass. A second placement pattern 400A is also arranged over substrate 102A for arranging components during a second pass. By consecutively performing the first and second passes, it can be ensured that substrate 102A is entirely filled with components. Furthermore, placement patterns 102A, 102A represent translated copies of each other.

[0062] Placements patterns 400A-400C can be processed by allowing the target supporting unit to make a serpentine-based motion. For example, the movable target table may start at the upper left corner of substrate 102A and first perform a right-to-left motion. When it reaches the edge on the right of substrate 102A it shifts one row up and performs a left-to-right motion. When it reaches the edge on the left of substrate 102A it shifts up a row and the motions described above can be repeated.

[0063] FIG. 4 illustrates another example of a placement patterns 400D in accordance with an aspect of the present disclosure. Compared to placement patterns 400A-400C, unit cell 401D is two dimensional instead of a 1 by n configuration. For example, unit cell 401D spans 5 by 5 positions.

[0064] Unit cell 401D offers the advantage of improved randomness when using this placement pattern for arranging components on substrate 102A. Such randomness improves the uniformity of the components on substrate 102A.

[0065] Unit cell 401D can be obtained by using a column index n as shown in FIG. 4. The offset Off in the column direction to be used for a given column index can be found using:

Off=mod(n+n floor(N/B),N)

[0066] where N is the number of passes, B a constant, mod (a, b) a function returning the remainder when a is divided by b, and floor (a) rounding off a to its lowest neighboring integer. For example, for unit cell 401D, N=5 and B=5 yields:

Off for n=0 equals mod(0+0floor(5/5),1)=0

Off for n=1 equals mod(1+1floor(5/5),1)=2

Off for n=2 equals mod(2+2floor(5/5),1)=4

Off for n=3 equals mod(3+3floor(5/5),1)=1

Off for n=4 equals mod(4+4floor(5/5),1)=3

[0067] In the discussion above nothing was mentioned about the manner in which components are collected from the carrier. For collecting the components, similar patterns can be used as the placement patterns described above. However, for minimizing the movements of the source supporting unit, it is preferred if this table makes relatively simple movements. For example, the collect patterns can be similar to that of placement pattern 400C. Instead of skipping a single row, multiple rows could be skipped. This would improve the uniformity of the display panel but would result in a decrease in throughput as the source supporting unit would be required to move more.

[0068] In an embodiment, the pick-and-place apparatus according to an aspect of the present disclosure is configured as the apparatus in FIG. 1 with the exception that controller 110 is adapted to control first drive unit 108, second drive unit 109, and transport unit 103 to enable the pick-and-place method as described above.

[0069] In a further embodiment, the controller may be configured to receive data describing the collect patterns and/or placement patterns to be used during the pick-and-place process. In this embodiment, these patterns are computed and/or determined remote from the pick-and-place apparatus. Alternatively, the controller may be configured to receive user input, for example using a user interface, that describes parameters of the collect and/or placement patterns. Examples of such parameters can be the number of rows to skip when switching between rows during component collect, and/or the number of positions to skip in the row and/or column direction when switching between rows and/or columns, respectively during component placement.

[0070] To assist in determining the collect and/or placement patterns, a uniformity metric may be used. This metric describes the uniformity of one or more parameters, such as brightness or the color of LEDs, describing the performance of the components over the substrate. Such metric should be indicative of how much a local average parameter value deviates from the average value of that parameter over the entire substrate, i.e. the so-called global average value. For example, the local average parameter value for a given position on the substrate can be determined by determining the average of the parameter value at that position and the parameter values of the nearest neighbors at that position. This process is illustrated in FIG. 5.

[0071] For example, in FIG. 5, the local average value for position P1 can be computed using (2+3+1+1+3+2+1+2+1)/9=16/9, which in FIG. 5 is rounded off to the nearest integer 2. At the edges, where the number of nearest neighbors is less than 8, substitute values may be used. For example, for position P2 the local average value can be computed using (Av+Av+Av+Av+1+1+Av+2+2)/9, wherein Av is the global average value of the parameter. Instead of using substitute values, the window may be reduced taking only into account the positions for which a value is known. For example, the local average value for the upper left corner can be computed using (1+1+2+2)/4=6/4, which in FIG. 5 is rounded off to the nearest integer 2 as shown on the right.

[0072] Having computed a local average value at each position, it can be compared to the global average value. For example, a metric can be defined as the ratio between the global average value and the standard deviation of the collection of local average values. In this case, the value of the metric is high when the standard deviation is low.

[0073] The abovementioned metric is a uniformity metric describing uniformity over the substrate. This metric depends on the collect and placement patterns that are used during the pick-and-place process and the wafer map. The throughput of the pick-and-place apparatus is also determined by these patterns. For example, the more passes are required to fill a substrate, the lower the throughput will be. In addition, more complex patterns, such as that shown in FIG. 4, require more movement of the target supporting unit than less complex patterns such as those shown in FIG. 3.

[0074] A throughput metric can be used that for example corresponds to a time required for completely filling a substrate or to a number of substrates that can be filled in a certain time interval. Using the uniformity metric and throughput metric, a general metric can be constructed that describes the trade off between uniformity over the substrate and the throughput. For example, assuming that the throughput metric Mt describes the number of substrates filled within a certain time interval, a general metric Mg can be computed using Mg=w1Mu+w2Mt, wherein Mu is the uniformity metric, and w1 and w2 are weighing constants.

[0075] The throughput metric, uniformity metric, and general metric can be computed for each combination of collect and placement patterns. In an embodiment, the metrics are determined for a given collection of different combinations of patterns. This allows the best combination to be selected for a given wafer map.

[0076] Controller 110 may be configured to automatically determine the best combination. To that end, it may comprise a pattern determination unit that takes the wafer map and determines the general metric for each combination of collect and placement patterns among a predefined collection of such combinations. Having determined the best combination, it uses the associated collect and placement patterns for the pick-and-place process. It should be noted that instead of using a pattern determination unit that is part of and/or embodied by controller 110 for performing these calculations, an external device could equally be used of which the output is fed to controller 110, either manually or automatically.

[0077] Particular and preferred aspects of the disclosure are set out in the accompanying independent claims. Combinations of features from the dependent and/or independent claims may be combined as appropriate and not merely as set out in the claims.

[0078] For example, FIG. 1 illustrates a particular transport unit. Embodiments of the present disclosure may however include a different type of transport unit that collects a component from the carrier and places the collected component on the substrate.

[0079] The scope of the present disclosure includes any novel feature or combination of features disclosed therein either explicitly or implicitly or any generalization thereof irrespective of whether or not it relates to the claimed disclosure or mitigate against any or all of the problems addressed by the present disclosure. The applicant hereby gives notice that new claims may be formulated to such features during prosecution of this application or of any such further application derived therefrom. In particular, with reference to the appended claims, features from dependent claims may be combined with those of the independent claims and features from respective independent claims may be combined in any appropriate manner and not merely in specific combinations enumerated in the claims.

[0080] Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination.

[0081] The term comprising does not exclude other elements or steps, the term a or an does not exclude a plurality. Reference signs in the claims shall not be construed as limiting the scope of the claims.