SYSTEMS AND METHODS FOR BONDING SEMICONDUCTOR ELEMENTS
A bonding machine for bonding semiconductor elements, the bonding machine including: a support structure for supporting a substrate; a bond head assembly, the bond head assembly including a bonding tool configured to bond a plurality of semiconductor elements to the substrate; an alignment structure including first alignment markings; an alignment element configured to be placed on the alignment structure using the bonding tool, the alignment element including second alignment markings; an imaging system configured to image relative positions of the first alignment markings and corresponding ones of the second alignment markings; and a computer system configured to provide an adjustment to a position of at least one of the bonding tool and the support structure during bonding of ones of the plurality of semiconductor elements to the substrate, the computer being configured to provide the adjustment at least partially based on the relative positions of the first alignment markings and the corresponding ones of the second alignment markings, the adjustment being specific to bonding of the ones of the plurality of semiconductor elements to a corresponding region of the substrate.
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This application claims the benefit of U.S. Provisional Patent Application No. 61/911,226 filed Dec. 3, 2013, the content of which is incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention relates to the formation of semiconductor packages, and more particularly, to improved systems and methods for bonding semiconductor elements to bonding locations.
BACKGROUND OF THE INVENTIONIn certain aspects of the semiconductor packaging industry, semiconductor elements are bonded to bonding locations. For example, in conventional die attach applications (also known as die bonding), a semiconductor die is bonded to a bonding location (e.g., a leadframe, another die in stacked die applications, a spacer, etc.). In advanced packaging applications (e.g., flip chip bonding, thermocompression bonding), semiconductor elements (e.g., bare semiconductor die, packaged semiconductor die, etc.) are bonded to bonding locations, with conductive structures (e.g., conductive bumps, contact pads, solder bumps, conductive pillars, copper pillars, etc.) disposed therebetween.
It is desirable that bonding machines (e.g., thermocompressive bonding machines, thermosonic bonding machines, ultrasonic bonding machines, etc.) be configured to accurately place and bond a semiconductor element to a bonding location. However, various inaccuracies and error sources exist in such bonding machines. Such inaccuracies and error sources are not identical from machine to machine, or from application to application. This results in challenges to the machine user and/or operator to consistently and accurately place and bond semiconductor elements.
Thus, it would be desirable to provide improved systems for, and methods of, bonding semiconductor elements to bonding locations.
SUMMARY OF THE INVENTIONAccording to an exemplary embodiment of the present invention, a bonding machine for bonding semiconductor elements includes: (1) a support structure for supporting a substrate; (2) a bond head assembly, the bond head assembly including a bonding tool configured to bond a plurality of semiconductor elements to the substrate; (3) an alignment structure including first alignment markings; (4) an alignment element configured to be placed on the alignment structure using the bonding tool, the alignment element including second alignment markings; (5) an imaging system configured to image relative positions of the first alignment markings and corresponding ones of the second alignment markings; and (6) a computer system configured to provide an adjustment to a position of at least one of the bonding tool and the support structure during bonding of ones of the plurality of semiconductor elements to the substrate, the computer being configured to provide the adjustment at least partially based on the relative positions of the first alignment markings and the corresponding ones of the second alignment markings, the adjustment being specific to bonding of the ones of the plurality of semiconductor elements to a corresponding region of the substrate.
According to another exemplary embodiment of the present invention, a method of operating a bonding machine is provided. The bonding machine includes a bonding tool configured to bond a semiconductor element to a substrate. The method includes the steps of: (a) providing an alignment structure on the bonding machine, the alignment structure including a plurality of first alignment markings; (b) selecting an area of the alignment structure based on a region of the substrate to be bonded with the semiconductor element, the substrate configured to be supported by a support structure of the bonding machine; (c) imaging ones of second alignment markings on an alignment element along with ones of the first alignment markings on the area of the alignment structure; and (d) adjusting a position of at least one of the bonding tool and the support structure during a subsequent bonding process using information provided from step (c).
According to another exemplary embodiment of the present invention, a method of bonding a plurality of semiconductor elements to a substrate with a bonding tool is provided. The method includes the steps of: (a) placing an alignment element over each of a plurality of areas of an alignment structure, each of the plurality of areas corresponding to one of a plurality of regions of a substrate supported by a support structure; (b) determining an offset of the alignment element with respect to each of the plurality of areas; and (c) adjusting a position of at least one of (1) the bonding tool and (2) the support structure during bonding of a plurality of semiconductor elements to each of the plurality of regions of the substrate, the position adjustment for each of the plurality of regions being related to the offset determined for the area corresponding to each of the plurality of regions.
The invention is best understood from the following detailed description when read in connection with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures:
As used herein, the term “semiconductor element” is intended to refer to any structure including (or configured to include at a later step) a semiconductor chip or die. Exemplary semiconductor elements include a bare semiconductor die, a semiconductor die on a substrate (e.g., a leadframe, a PCB, a carrier, a semiconductor wafer, a BGA substrate, etc.), a packaged semiconductor device, a flip chip semiconductor device, a die embedded in a substrate, a stack of semiconductor die, amongst others. Further, the semiconductor element may include an element configured to be bonded or otherwise included in a semiconductor package (e.g., a spacer to be bonded in a stacked die configuration, a substrate, an interposer, etc.).
In accordance with certain exemplary embodiments of the present invention, if an alignment element placed using a bonding tool is misaligned with a portion of a bonding machine alignment structure over which it is placed (where misalignment is determined, for example, using predetermined criteria such as a predetermined degree of misalignment), positions of a bonding tool (and/or a support structure of a substrate) are adjusted, based upon the misalignment, during bonding of semiconductor elements to bonding locations in a corresponding region (e.g., a row of bonding locations) of the substrate. An imaging system images the alignment element over the portion of the alignment structure and the misalignment is determined based upon the image(s) using a computer system of the bonding machine. Such adjustment provides for improved bonding accuracy as compared to conventional methods.
As will be appreciated by those skilled in the art, a thermocompression bonding machine (such as machine 100 in
Bonding machine 100 also includes bond head assembly 106 (illustrated as moving along the y and z axes—see the legend, as well as about a theta (θ) axis—but may move in other directions, as desired), semiconductor element source 108 (e.g., a semiconductor wafer), and pick tool 110 (illustrated as moving along the x axis—but may move in other directions, as desired). In an exemplary operation, pick tool 110 removes a semiconductor element (e.g., a bare die) from source 108. Pick tool 110, with the semiconductor element, moves along the x-axis to a transfer position (not shown). Bond head assembly 106 also moves to the transfer position, where the semiconductor element is transferred from pick tool 110 to a place tool (e.g., a bonding tool 106a, not shown in
The directions of motion (e.g., along x, y, and z-axes, and rotation about the theta (θ) axis) shown in
In
In the example illustrated in
Alignment element 364 may be stored in a location, for example, proximate, or on, bond head assembly 106 during bonding operations. So the bonding tool may then return alignment element 364 to that location. The bonding tool may then obtain semiconductor elements from pick tool 110 at the transfer position (see, e.g.,
While
First alignment markings 270, and second alignment markings (e.g., markings 360a, 360b, 362a, 362b, 364a, 364b, 366a-366c, and 366a′-366c′) as illustrated herein are exemplary in nature. That is, the markings are not limited to the style shown and described herein, the number shown and described herein, or the orientation shown and described herein. In practice, the first and second alignment markings may be very different than those shown and described with respect to, for example,
In contrast to
Referring specifically to
Of course, the illustration of bonding machine 100 in
In
As provided above (e.g., in connection with
As will be appreciated by those skilled in the art, an exemplary machine architecture has been described herein, wherein adjustments to the x-axis are made through motion of the support structures described herein (including but not limited to motion of fine x-axis motion system 608 in
In summary, and by reference to the exemplary architectures disclosed herein, after completing the alignment process (such as described above in connection with
While the present invention has been described largely in connection with a substrate (e.g., substrate 296) having rows and columns of bonding locations, wherein the alignment is accomplished row by row, it is not limited thereto.
Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.
Claims
1. A bonding machine for bonding semiconductor elements, the bonding machine comprising:
- a support structure for supporting a substrate;
- a bond head assembly, the bond head assembly including a bonding tool configured to bond a plurality of semiconductor elements to the substrate;
- an alignment structure including first alignment markings;
- an alignment element configured to be placed on the alignment structure using the bonding tool, the alignment element including second alignment markings;
- an imaging system configured to image relative positions of the first alignment markings and corresponding ones of the second alignment markings; and
- a computer system configured to provide an adjustment to a position of at least one of the bonding tool and the support structure during bonding of ones of the plurality of semiconductor elements to the substrate, the computer being configured to provide the adjustment at least partially based on the relative positions of the first alignment markings and the corresponding ones of the second alignment markings, the adjustment being specific to bonding of the ones of the plurality of semiconductor elements to a corresponding region of the substrate.
2. The bonding machine of claim 1 wherein the adjustment is specific to a y-axis position of the substrate.
3. The bonding machine of claim 1 wherein the adjustment is specific to an x-axis position of the substrate.
4. The bonding machine of claim 1 wherein the alignment element is at least partially transparent such that the first alignment markings of the alignment structure are visible to the imaging system when the alignment element is positioned above the first alignment markings.
5. The bonding machine of claim 1 wherein the alignment structure is secured to the support structure.
6. The bonding machine of claim 1 further comprising a motion system for moving the support structure along a horizontal axis of the bonding machine, the alignment structure being secured to the support structure such that the alignment structure is moved along the horizontal axis with the support structure.
7. The bonding machine of claim 1 wherein a separation is defined between a portion of the alignment element and the alignment structure.
8. The bonding machine of claim 1 wherein the alignment element is configured to be held on the alignment structure using a holding force.
9. The bonding machine of claim 8 where the holding force is provided by at least one of a vacuum force and a magnetic force.
10. The bonding machine of claim 1 wherein the second alignment markings of the alignment element are configured to be aligned with the first alignment markings of the alignment structure.
11. The bonding machine of claim 1 wherein the corresponding ones of the second alignment markings include groups of markings, each of the groups of markings being configured for alignment with a corresponding portion of the first alignment markings.
12. The bonding machine of claim 1 wherein a portion of the second alignment markings are selected to be aligned with a corresponding portion of the first alignment markings based upon a size of bonding areas of the substrate.
13. The bonding machine of claim 1 wherein the corresponding region of the substrate is a row of bonding areas of the substrate.
14. The bonding machine of claim 1 wherein the corresponding region of the substrate is a column of bonding areas of the substrate.
15. The bonding machine of claim 1 wherein the alignment element comprises glass.
16. The bonding machine of claim 14 wherein after placement of the alignment element on the alignment structure, the first alignment markings are provided on a top surface of the alignment structure, and the second alignment markings are provided on a bottom surface of the alignment element.
17. A method of operating a bonding machine, the bonding machine including a bonding tool configured to bond a semiconductor element to a substrate, the method comprising the steps of:
- (a) providing an alignment structure on the bonding machine, the alignment structure including a plurality of first alignment markings;
- (b) selecting an area of the alignment structure based on a region of the substrate to be bonded with the semiconductor element, the substrate configured to be supported by a support structure of the bonding machine;
- (c) imaging ones of second alignment markings on an alignment element along with ones of the first alignment markings on the area of the alignment structure; and
- (d) adjusting a position of at least one of the bonding tool and the support structure during a subsequent bonding process using information provided from step (c).
18. The method of claim 17 further comprising the step of placing the alignment element on the alignment structure using the bonding tool.
19. The method of claim 17 wherein the region of the substrate includes a row or column of bonding locations configured to be bonded with ones of the semiconductor element.
20. The method of claim 17 wherein the alignment element is at least partially transparent such that during step (c) the ones of the first alignment markings are imaged with the alignment element being positioned above the area of the alignment structure.
21. The method of claim 17 wherein the alignment structure is secured to the support structure.
22. The method of claim 17 further comprising the step of holding the alignment element on the area of the alignment structure using a holding force.
23. The method of claim 22 wherein the holding force is provided by at least one of a vacuum force and a magnetic force.
24. The method of claim 17 further comprising the step of determining an adjustment of the position for use in step (d) with an algorithm using the information provided from step (c), the information including relative positions of the ones of the first alignment markings and the ones of the second alignment markings.
25. A method of bonding a plurality of semiconductor elements to a substrate with a bonding tool, the method comprising the steps of:
- (a) placing an alignment element over each of a plurality of areas of an alignment structure, each of the plurality of areas corresponding to one of a plurality of regions of a substrate supported by the alignment structure;
- (b) determining an offset of the alignment element with respect to each of the plurality of areas; and
- (c) adjusting a position of at least one of (1) the bonding tool and (2) the support structure during bonding of a plurality of semiconductor elements to each of the plurality of regions of the substrate, the position adjustment for each of the plurality of regions being related to the offset determined for the area corresponding to each of the plurality of regions.
26. The method of claim 25 wherein each of the plurality of regions corresponds to at least one row of bonding locations of the substrate.
27. The method of claim 25 wherein each of the plurality of regions corresponds to at least one column of bonding locations of the substrate.
28. The method of claim 25 wherein step (b) includes imaging the alignment element over each of the plurality of areas.
29. The method of claim 25 wherein the alignment structure includes first alignment markings and the alignment element includes second alignment markings.
30. The method of claim 29 wherein the alignment element is at least partially transparent such that ones of the first alignment markings of the alignment structure are visible to an imaging system when the alignment element is positioned over the first alignment markings.
31. The method of claim 29 wherein the offset of the alignment element is determined using relative positions of the second alignment markings from a corresponding portion of the first alignment markings.
32. The method of claim 29 wherein the second alignment markings of the alignment element are configured to be aligned with a portion of the first alignment markings of the alignment structure.
33. The method of claim 29 wherein ones of the second alignment markings include groups of markings, each of the groups of markings being configured for alignment with a portion of the first alignment markings.
34. The method of claim 29 including the step of aligning a portion of the second alignment markings with a corresponding portion of the first alignment markings based upon a size of a bonding area of each of the plurality of regions of the substrate.
35. The method of claim 29 wherein the first alignment markings are provided on a top surface of the alignment structure, and the second alignment markings are provided on a bottom surface of the alignment element.
36. The method of claim 25 further comprising the step of providing a separation between a portion of the alignment element and the alignment structure.
37. The method of claim 25 further comprising the step of applying a holding force to hold the alignment element on each of the plurality of areas of the alignment structure.
38. The method of claim 37 wherein the holding force is provided by at least one of a vacuum and a magnetic force.
39. The method of claim 25 wherein the alignment element comprises glass.
Type: Application
Filed: Nov 25, 2014
Publication Date: Jun 4, 2015
Applicant: Kulicke and Soffa Industries, Inc. (Fort Washington, PA)
Inventors: James E. Eder (Doylestown, PA), David C. Schalcosky (North Wales, PA)
Application Number: 14/553,049