US20080271313A1

US20080271313A1 - Method, system, and apparatus for transfer of dies using a die plate

Info

Publication number: US20080271313A1
Application number: US12/136,565
Authority: US
Inventors: Michael R. Arneson; William R. Bandy
Original assignee: Symbol Technologies LLC
Current assignee: Symbol Technologies LLC
Priority date: 2003-06-12
Filing date: 2008-06-10
Publication date: 2008-11-06
Also published as: WO2004112096A2; US20050015970A1; US20040250949A1; US20040250417A1; US20060174257A1; US20050009232A1; WO2004112096A3; US20050005434A1; US7223320B2; US7795076B2; US20050007252A1; EP1642325A2; US7543316B2; US7404199B2; US20040251541A1; US7276388B2; TW200504809A

Abstract

A method, system, and apparatus for transfer of dies using a die plate is described herein. The die plate has a planar body. The body has a plurality of holes therethrough. A support structure and the die plate can be positioned to be closely adjacent to each other such that each die of a plurality of dies attached to the support structure adheres to a first surface of the die plate. The dies can subsequently be transferred from the die plate to one or more destination substrates or other surfaces, by a punching mechanism.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Non-Provisional application Ser. No. 10/866,253, filed Jun. 14, 2004, which claims the benefit of U.S. Provisional Application No. 60/477,735, filed Jun. 12, 2003, all of which are herein incorporated by reference in their entirety as if reproduced in full below.
The following applications of common assignee are related to the present application, have the same filing date (Jun. 14, 2004) as the parent application, and are herein incorporated by reference in their entirety as if reproduced in full below:
“Method And Apparatus For Expanding A Semiconductor Wafer,” U.S. Ser. No. 10/866,148, now U.S. Pat. No. 7,223,320;
“Method, System, And Apparatus For Authenticating Devices During Assembly,” U.S. Ser. No. 10/866,152, now U.S. Pat. No. 7,276,388;
“Method, System, And Apparatus For Transfer Of Dies Using A Die Plate Having Die Cavities,” U.S. Ser. No. 10/866,150, U.S. Patent Publication No. 2005-0009232, published Jan. 13, 2005;
“Method, System, And Apparatus For Transfer Of Dies Using A Pin Plate,” U.S. Ser. No. 10/866,159, U.S. Patent Publication No. 2005-0015970, published Jan. 27, 2005;
“Method, System, And Apparatus For High Volume Transfer Of Dies,” U.S. Ser. No. 10/866,149, U.S. Patent Publication No. 2005-0005434, published Jan. 13, 2005; and
“Method, System, And Apparatus For High Volume Assembly Of Compact Discs And Digital Video Discs Incorporating Radio Frequency Identification Tag Technology,” U.S. Ser. No. 10/866,151, U.S. Patent Publication 2004-0251541, published Dec. 16, 2004.
The following applications of common assignee are related to the present application, and are herein incorporated by reference in their entirety as if reproduced in full below:
“Method and Apparatus for High Volume Assembly of Radio Frequency Identification Tags,” U.S. Provisional App. No. 60/400,101, filed Aug. 2, 2002;
“Method and Apparatus for High Volume Assembly of Radio Frequency Identification Tags,” Ser. No. 10/322,467, filed Dec. 19, 2002, now U.S. Pat. No. 7,117,581;
“Multi-Barrel Die Transfer Apparatus and Method for Transferring Dies Therewith,” Ser. No. 10/322,718, filed Dec. 19, 2002, now U.S. Pat. No. 6,915,551;
“Die Frame Apparatus and Method of Transferring Dies Therewith,” Ser. No. 10/322,701, filed Dec. 19, 2002, now U.S. Pat. No. 7,102,524;
“System and Method of Transferring Dies Using an Adhesive Surface,” Ser. No. 10/322,702, filed Dec. 19, 2002, now U.S. Pat. No. 6,848,162; and
“Method and System for Forming a Die Frame and for Transferring Dies Therewith,” Ser. No. 10/429,803, filed May 6, 2003, now U.S. Pat. No. 7,023,347.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to the assembly of electronic devices. More particularly, the present invention relates to the transfer of dies from wafers to substrates, including substrates of radio frequency identification (RFID) tags.
2. Related Art
Pick and place techniques are often used to assemble electronic devices. Such techniques involve a manipulator, such as a robot arm, to remove integrated circuit (IC) dies from a wafer and place them into a die carrier. The dies are subsequently mounted onto a substrate with other electronic components, such as antennas, capacitors, resistors, and inductors to form an electronic device.
Pick and place techniques involve complex robotic components and control systems that handle only one die at a time. This has a drawback of limiting throughput volume. Furthermore, pick and place techniques have limited placement accuracy, and have a minimum die size requirement.
One type of electronic device that may be assembled using pick and place techniques is an RFID “tag.” An RFID tag may be affixed to an item whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the tag is affixed, may be checked and monitored by devices known as “readers.”
As market demand increases for products such as RFID tags, and as die sizes shrink, high assembly throughput rates for very small die, and low production costs are crucial in providing commercially-viable products. Accordingly, what is needed is a method and apparatus for high volume assembly of electronic devices, such as RFID tags, that overcomes these limitations.

SUMMARY OF THE INVENTION

The present invention is directed to methods, systems, and apparatuses for producing one or more electronic devices, such as RFID tags, that each include a die having one or more electrically conductive contact pads that provide electrical connections to related electronics on a substrate.
According to the present invention, electronic devices are formed at much greater rates than conventionally possible. In one aspect, large quantities of dies can be transferred directly from a wafer to corresponding substrates of a web of substrates. In another aspect, large quantities of dies can be transferred from a support surface to corresponding substrates of a web of substrates. In another aspect, large quantities of dies can be transferred from a wafer or support surface to an intermediate surface, such as a die plate. The die plate may have cells formed in a surface thereof in which the dies reside. Otherwise, the dies can reside on a surface of the die plate. The dies of the die plate can then be transferred to corresponding substrates of a web of substrates.
In an aspect of the present invention, methods, systems, and apparatuses for transfer of dies using the die plate are described herein. The die plate has a planar body. The body has a plurality of holes therethrough.
In a further aspect, a support structure and the die plate can be positioned to be closely adjacent to each other such that each die of a plurality of dies attached to the support structure adheres to a first surface of the die plate. The dies can subsequently be transferred from the die plate to one or more destination substrates or other surfaces, by a punching or other mechanism.
In an aspect, a punch plate, punch roller or cylinder, or expandable material can be used to transfer dies from the die plate to substrates.
Large quantities of dies can be transferred. For example, 10 s, 100 s, 1000 s, or more dies, or even all dies of a wafer, support surface, or die plate, can be simultaneously transferred to corresponding substrates of a web.
In one aspect, dies may be transferred between surfaces in a “pads up” orientation. When dies are transferred to a substrate in a “pads up” orientation, related electronics can be printed or otherwise formed to couple contact pads of the die to related electronics of the tag substrate.
In an alternative aspect, the dies may be transferred between surfaces in a “pads down” orientation. When dies are transferred to a substrate in a “pads down” orientation, related electronics can be pre-printed or otherwise pre-deposited on the tag substrates.
These and other advantages and features will become readily apparent in view of the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

FIG. 1A shows a block diagram of an exemplary RFID tag, according to an embodiment of the present invention.

FIGS. 1B and 1C show detailed views of exemplary RFID tags, according to embodiments of the present invention.

FIGS. 2A and 2B show plan and side views of an exemplary die, respectively.

FIGS. 2C and 2D show portions of a substrate with a die attached thereto, according to example embodiments of the present invention.

FIG. 3 is a flowchart illustrating a tag assembly process, according to embodiments of the present invention.

FIGS. 4A and 4B are plan and side views of a wafer having multiple dies affixed to a support surface, respectively.

FIG. 5 is a view of a wafer having separated dies affixed to a support surface.

FIG. 6 shows a system diagram illustrating example options for transfer of dies from wafers to substrates, according to embodiments of the present invention.

FIGS. 7 and 8 show flowcharts providing steps for transferring dies from a first surface to a second surface, according to embodiments of the present invention.

FIG. 9 shows a perspective view of an example die plate, according to an example embodiment of the present invention.

FIGS. 10A-10E show multiple schematic views of an example die plate, according to an embodiment of the present invention.

FIG. 11 shows a perspective view of a portion of a surface of a die plate, according to an embodiment of the present invention.

FIG. 12 shows a flowchart providing example steps for transferring dies from a support structure to a die plate, according to embodiments of the present invention.

FIGS. 13-15 show example implementations of the steps of the flowchart of FIG. 12, according to embodiments of the present invention.

FIG. 16 shows a flowchart providing example steps for transferring dies from a wafer to a die plate, according to embodiments of the present invention.

FIGS. 17-19 show example implementations of the steps of the flowchart of FIG. 16, according to embodiments of the present invention.

FIGS. 20-26 show various views of a transfer of dies to a die plate, and subsequently to one or more substrates, according to embodiments of the present invention.

FIG. 27 shows a flowchart providing steps for transferring dies, according to embodiments of the present invention.

The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides improved processes and systems for assembling electronic devices, including RFID tags. The present invention provides improvements over current processes. Conventional techniques include vision-based systems that pick and place dies one at a time onto substrates. The present invention can transfer multiple dies simultaneously. Vision-based systems are limited as far as the size of dies that may be handled, such as being limited to dies larger than 600 microns square. The present invention is applicable to dies 100 microns square and even smaller.
Furthermore, yield is poor in conventional systems, where two or more dies may be accidentally picked up at a time, causing losses of additional dies. The present invention allows for improved yield values.
The present invention provides an advantage of simplicity. Conventional die transfer tape mechanisms may be used by the present invention. Furthermore, much higher fabrication rates are possible. Current techniques process 5-8 thousand units per hour. The present invention can provide improvements in these rates by a factor of N. For example, embodiments of the present invention can process dies 5 times as fast as conventional techniques, at 100 times as fast as conventional techniques, and at even faster rates. Furthermore, because the present invention allows for flip-chip die attachment techniques, wire bonds are not necessary.
Elements of the embodiments described herein may be combined in any manner. Example RFID tags are described in the section below. Assembly embodiments for RFID tags are described in the next section. Example applications for tags and tag assembly techniques are then described, followed by a description of example substrate webs and antenna layouts.

1.0 RFID Tag

The present invention is directed to techniques for producing electronic devices, such as RFID tags. For illustrative purposes, the description herein primarily relates to the production of RFID tags. However, the description is also adaptable to the production of further electronic device types, as would be understood by persons skilled in the relevant art(s) from the teachings herein.
FIG. 1A shows a block diagram of an exemplary RFID tag 100, according to an embodiment of the present invention. As shown in FIG. 1A, RFID tag 100 includes a die 104 and related electronics 106 located on a tag substrate 116. Related electronics 106 includes an antenna 114 in the present example. FIGS. 1B and 1C show detailed views of exemplary RFID tags 100, indicated as RFID tags 100 a and 100 b. As shown in FIGS. 1B and 1C, die 104 can be mounted onto antenna 114 of related electronics 106. As is further described elsewhere herein, die 104 may be mounted in either a pads up or pads down orientation.
RFID tag 100 may be located in an area having a large number, population, or pool of RFID tags present. RFID tag 100 receives interrogation signals transmitted by one or more tag readers. According to interrogation protocols, RFID tag 100 responds to these signals. Each response includes information that identifies the corresponding RFID tag 100 of the potential pool of RFID tags present. Upon reception of a response, the tag reader determines the identity of the responding tag, thereby ascertaining the existence of the tag within a coverage area defined by the tag reader.
RFID tag 100 may be used in various applications, such as inventory control, airport baggage monitoring, as well as security and surveillance applications. Thus, RFID tag 100 can be affixed to items such as airline baggage, retail inventory, warehouse inventory, automobiles, compact discs (CDs), digital video discs (DVDs), video tapes, and other objects. RFID tag 100 enables location monitoring and real time tracking of such items.
In the present embodiment, die 104 is an integrated circuit that performs RFID operations, such as communicating with one or more tag readers (not shown) according to various interrogation protocols. Exemplary interrogation protocols are described in U.S. Pat. No. 6,002,344 issued Dec. 14, 1999 to Bandy et al. entitled System and Method for Electronic Inventory, and U.S. patent application Ser. No. 10/072,885, filed on Feb. 12, 2002, both of which are incorporated by reference herein in its entirety. Die 104 includes a plurality of contact pads that each provide an electrical connection with related electronics 106.
Related electronics 106 are connected to die 104 through a plurality of contact pads of IC die 104. In embodiments, related electronics 106 provide one or more capabilities, including RF reception and transmission capabilities, sensor functionality, power reception and storage functionality, as well as additional capabilities. The components of related electronics 106 can be printed onto a tag substrate 116 with materials, such as conductive inks. Examples of conductive inks include silver conductors 5000, 5021, and 5025, produced by DuPont Electronic Materials of Research Triangle Park, N.C. Other materials or means suitable for printing related electronics 106 onto tag substrate 116 include polymeric dielectric composition 5018 and carbon-based PTC resistor paste 7282, which are also produced by DuPont Electronic Materials of Research Triangle Park, N.C. Other materials or means that may be used to deposit the component material onto the substrate would be apparent to persons skilled in the relevant art(s) from the teachings herein.
As shown in FIGS. 1A-1C, tag substrate 116 has a first surface that accommodates die 104, related electronics 106, as well as further components of tag 100. Tag substrate 116 also has a second surface that is opposite the first surface. An adhesive material or backing can be included on the second surface. When present, the adhesive backing enables tag 100 to be attached to objects, such as books and consumer products. Tag substrate 116 is made from a material, such as polyester, paper, plastic, fabrics such as cloth, and/or other materials such as commercially available Tyvec®.
In some implementations of tags 100, tag substrate 116 can include an indentation, “cavity,” or “cell” (not shown in FIGS. 1A-1C) that accommodates die 104. An example of such an implementation is included in a “pads up” orientation of die 104.
FIGS. 2A and 2B show plan and side views of an example die 104. Die 104 includes four contact pads 204 a-d that provide electrical connections between related electronics 106 and internal circuitry of die 104. Note that although four contact pads 204 a-d are shown, any number of contact pads may be used, depending on a particular application. Contact pads 204 are made of an electrically conductive material during fabrication of the die. Contact pads 204 can be further built up if required by the assembly process, by the deposition of additional and/or other materials, such as gold and solder flux. Such post processing, or “bumping,” will be known to persons skilled in the relevant art(s).
FIG. 2C shows a portion of a substrate 116 with die 104 attached thereto, according to an example embodiment of the present invention. As shown in FIG. 2C, contact pads 204 a-d of die 104 are coupled to respective contact areas 210 a-d of substrate 116. Contact areas 210 a-d provide electrical connections to related electronics 106. The arrangement of contact pads 204 a-d in a rectangular (e.g., square) shape allows for flexibility in attachment of die 104 to substrate 116, and good mechanical adherement. This arrangement allows for a range of tolerance for imperfect placement of IC die 104 on substrate 116, while still achieving acceptable electrical coupling between contact pads 204 a-d and contact areas 210 a-d. For example, FIG. 2D shows an imperfect placement of IC die 104 on substrate 116. However, even though IC die 104 has been improperly placed, acceptable electrical coupling is achieved between contact pads 204 a-d and contact areas 210 a-d.
Note that although FIGS. 2A-2D show the layout of four contact pads 204 a-d collectively forming a rectangular shape, greater or lesser numbers of contact pads 204 may be used. Furthermore, contact pads 204 a-d may be laid out in other shapes in embodiments of the present invention.

2.0 RFID Tag Assembly

The present invention is directed to continuous-roll assembly techniques and other techniques for assembling tags, such as RFID tag 100. Such techniques involve a continuous web (or roll) of the material of the tag antenna substrate 116 that is capable of being separated into a plurality of tags. Alternatively, separate sheets of the material can be used as discrete substrate webs that can be separated into a plurality of tags. As described herein, the manufactured one or more tags can then be post processed for individual use. For illustrative purposes, the techniques described herein are made with reference to assembly of RFID tag 100. However, these techniques can be applied to other tag implementations and other suitable devices, as would be apparent to persons skilled in the relevant art(s) from the teachings herein.
The present invention advantageously eliminates the restriction of assembling electronic devices, such as RFID tags, one at a time, allowing multiple electronic devices to be assembled in parallel. The present invention provides a continuous-roll technique that is scalable and provides much higher throughput assembly rates than conventional pick and place techniques.
FIG. 3 shows a flowchart 300 with example steps relating to continuous-roll production of RFID tags 100, according to example embodiments of the present invention. FIG. 3 shows a flowchart illustrating a process 300 for assembling tags 100. Process 300 begins with a step 302. In step 300, a wafer 400 having a plurality of dies 104 is produced. FIG. 4A illustrates a plan view of an exemplary wafer 400. As illustrated in FIG. 4A, a plurality of dies 104 are arranged in a plurality of rows 402 a-n.
In a step 304, wafer 400 is optionally applied to a support structure or surface 404. Support surface 404 includes an adhesive material to provide adhesiveness. For example support surface 404 may be an adhesive tape that holds wafer 400 in place for subsequent processing. FIG. 4B shows an example view of wafer 400 in contact with an example support surface 404. In some embodiments, wafer 400 does not need to be attached to a support surface, and can be operated on directly.
In a step 306, the plurality of dies 104 on wafer 400 are separated. For example, step 306 may include scribing wafer 400 according to a process, such as laser etching. FIG. 5 shows a view of wafer 400 having example separated dies 104 that are in contact with support surface 404. FIG. 5 shows a plurality of scribe lines 502 a-1 that indicate locations where dies 104 are separated.
In a step 308, the plurality of dies 104 is transferred to a substrate. For example, dies 104 can be transferred from support surface 404 to tag substrates 116. Alternatively, dies 104 can be directly transferred from wafer 400 to substrates 116. In an embodiment, step 308 may allow for “pads down” transfer. Alternatively, step 308 may allow for “pads up” transfer. As used herein the terms “pads up” and “pads down” denote alternative implementations of tags 100. In particular, these terms designate the orientation of connection pads 204 in relation to tag substrate 116. In a “pads up” orientation for tag 100, die 104 is transferred to tag substrate 116 with pads 204 a-204 d facing away from tag substrate 116. In a “pads down” orientation for tag 100, die 104 is transferred to tag substrate 116 with pads 204 a-204 d facing towards, and in contact with tag substrate 116.
Note that step 308 may include multiple die transfer iterations. For example, in step 308, dies 104 may be directly transferred from a wafer 400 to substrates 116. Alternatively, dies 104 may be transferred to an intermediate structure, and subsequently transferred to substrates 116. Example embodiments of such die transfer options are described below.
Note that steps 306 and 308 can be performed simultaneously in some embodiments. This is indicated in FIG. 3 by step 320, which includes both of steps 306 and 308. Example embodiments where dies 104 of a wafer 400 are separated, and simultaneously transferred to a subsequent surface, are described below.
In a step 310, post processing is performed. During step 310, assembly of RFID tag(s) 100 is completed.

2.1 Die Transfer Embodiments

Step 308 shown in FIG. 3, and discussed above, relates to transferring dies to a tag substrate. The dies can be attached to a support surface (e.g., as shown in FIG. 5), or can be transferred directly from the wafer, and can be transferred to the tag substrate by a variety of techniques. Conventionally, the transfer is accomplished using a pick and place tool. The pick and place tool uses a vacuum die collet controlled by a robotic mechanism that picks up the die from the support structure by a suction action, and holds the die securely in the die collet. The pick and place tool deposits the die into a die carrier or transfer surface. For example, a suitable transfer surface is a “punch tape” manufactured by Mulbauer, Germany. A disadvantage of the present pick and place approach is that only one die at a time may be transferred. Hence, the present pick and place approach does not scale well for very high throughput rates.
The present invention allows for the transfer of more than one die at a time from a support surface to a transfer surface. In fact, the present invention allows for the transfer of more than one die between any two surfaces, including transferring dies from a wafer or support surface to an intermediate surface, transferring dies between multiple intermediate surfaces, transferring dies between an intermediate surface and the final substrate surface, and transferring dies directly from a wafer or support surface to the final substrate surface.
FIG. 6 shows a high-level system diagram 600 that provides a representation of the different modes or paths of transfer of dies from wafers to substrates. FIG. 6 shows a wafer 400, a web 608, and a transfer surface 610. Two paths are shown in FIG. 6 for transferring dies, a first path 602, which is a direct path, and a second path 604, which is a path having intermediate steps. For example, as shown in FIG. 6, first path 602 leads directly from wafer 400 to web 608. In other words, dies can be transferred from wafer 400 to substrates of web 608 directly, without the dies having first to be transferred from wafer 400 to another surface or storage structure. However, according to path 604, at least two steps are required, path 604A and path 604B. For path 604A, dies are first transferred from wafer 400 to an intermediate transfer surface 610. The dies then are transferred from transfer surface 610 via path 604B to the substrates of web 608. Paths 602 and 604 each have their advantages. For example, path 602 can have fewer steps, but can have issues of die registration, and other difficulties. Path 604 typically has a larger number of steps than path 602, but transfer of dies from wafer 400 to a transfer surface 610 can make die transfer to the substrates of web 608 easier, as die registration may be easier.
FIGS. 7 and 8 show flowcharts providing steps for transferring dies from a first surface to a second surface, according to embodiments of the present invention. Structural embodiments of the present invention will be apparent to persons skilled in the relevant art(s) based on the following discussion. These steps are described in detail below.
Flowchart 700 begins with step 702. In step 702, a plurality of dies attached to a support surface is received. For example, the dies are dies 104, which are shown attached to a support surface 404 in FIG. 4A. For example, the support surface can be a “green tape” or “blue tape” as would be known to persons skilled in the relevant art(s).
In step 704, the plurality of dies are transferred to a subsequent surface. For example, dies 104 may be transferred according to embodiments of the present invention. For example, the dies may be transferred by an adhesive tape, a punch tape, a multi-barrel transport mechanism and/or process, die frame, pin plate, such as are further described below and/or in the incorporated patent applications, and may be transferred by other mechanisms and processes, or by combinations of the mechanisms/processes described herein. In embodiments, the subsequent surface can be an intermediate surface or an actual final substrate. For example, the intermediate surface can be a transfer surface, including a “blue tape,” as would be known to persons skilled in the relevant art(s). When the subsequent surface is a substrate, the subsequent surface may be a substrate structure that includes a plurality of tag substrates, or may be another substrate type.
In block 706, if the subsequent surface is a substrate to which the dies are going to be permanently attached, the process of flowchart 700 is complete. The process can then proceed to step 310 of flowchart 300, if desired. If the subsequent surface is not a final surface, then the process proceeds to step 704, where the plurality of dies are then transferred to another subsequent surface. Step 704 may be repeated as many times as is required by the particular application.
Flowchart 800 of FIG. 8 is substantially similar to flowchart of 700. However, instead of including step 702, flowchart 800 includes step 802. In step 802, a wafer that includes a plurality of dies is received. Thus, in flowchart 800, a wafer 400 is operated on directly, without being applied to a support surface or structure. Embodiments for both of flowcharts 700 and 800 are described herein.
Any of the intermediate/transfer surfaces and final substrate surfaces may or may not have cells formed therein for dies to reside therein. Various processes described below may be used to transfer multiple dies simultaneously between first and second surfaces, according to embodiments of the present invention. In any of the processes described herein, dies may be transferred in either pads-up or pads-down orientations from one surface to another.
The die transfer processes described herein include transfer using an adhesive surface, a parallel die punch process, die plates, including die receptacle structures, pin plates, die transfer heads, and die transfer head coverage patterns. Elements of the die transfer processes described herein may be combined in any way, as would be understood by persons skilled in the relevant art(s). These die transfer processes, and related example structures for performing these processes, are further described in the following subsections.
2.1.1 Die Transfer onto a Die Plate
According to an embodiment of the present invention, a die plate is used for transferring dies from wafers or support surfaces to substrates or subsequent transfer services. According to die plate embodiments described herein, dies 104 can be attached to a surface of the die plate, being positioned over a corresponding hole of the die plate. Once a die is transferred to the die plate, the die can then be transferred to subsequent, intermediate/transfer surfaces, or to a final surface or structure, such as a substrate.
FIG. 9 shows an example die plate 900, according to an example embodiment of the present invention. As shown in FIG. 9, die plate 900 includes a body 902. As shown in FIG. 9, body 902 is substantially planar. Body 902 can be manufactured using materials including a metal or combination of metals/alloy, a polymer, a plastic, glass, other materials, and any combination thereof. Furthermore, as shown in FIG. 9, body 902 has a plurality of openings or holes 906 formed therethrough. Holes 906 are open at both the top and bottom planar surfaces of body 902. Although holes 906 are shown in FIG. 9 as being substantially round or elliptical, they can have other shapes, including square or rectangular, or other shape.
FIGS. 10A-E show example schematic views of die plate 900, according to an example embodiment. For example, FIG. 10A shows a die plate 900, and shows the outline of a wafer 400 superimposed on top of die plate 900. FIG. 10B also shows a die plate portion 1010 showing a close-up view of a surface of die plate 900. As shown for portion 1010, die plate 900 has a plurality of holes 906, and in this particular embodiment, includes a plurality of grid lines 1002. Grid lines 1002 can be formed on either or both of the bottom and top surfaces of die plate 900. Grid lines 1002 can be used to indicate areas for placement of dies 104 on die plate 900 and/or can be used as guidelines for sawing or otherwise separating dies 104 on die plate 1002. For example, grid lines 1002 can be grooves in the surface of die plate 900 for an end of a saw blade to pass through. FIG. 10C also shows a plan view of a die plate portion 1020.
FIG. 11 shows a perspective view of a die plate portion 1100, according to an embodiment of the present invention. As shown in FIG. 11, die plate portion 1100 includes holes 906, and grid lines 1002, which are shown as grooves in the surface of die plate 900.
FIG. 12 shows example steps related to a flowchart 1200 for transferring dies from a support structure to die plate 900, according to embodiments of the present invention. Further operational and structural embodiments of the present invention will be apparent to persons skilled in the relevant arts based on the following discussion.
FIGS. 13-15 relate to the steps of flowchart 1200 of FIG. 12. FIG. 13 shows a plurality of dies 104 attached in a pads-down fashion to a bottom surface of a support structure 404. FIG. 13 also shows a cross-sectional view of die plate 900. As shown in FIG. 13, an adhesive material layer 1302 has been formed on the top surface of die plate 900. Note that additionally or alternatively, an adhesive material can be applied to the bottom surfaces of dies 104. Adhesive material layer 1302 may be any type of adhesive material, including an epoxy, an adhesive tape, or any other adhesive material.
FIG. 14 shows an implementation of step 1202 of flowchart 1200 shown in FIG. 12. As shown in FIG. 14, support structure 404 and die plate 900 are positioned closely adjacent to each other, such that each die 104 attached to support structure 404 adheres to the top surface of die plate 900 due to adhesive material layer 1302.
FIG. 15 shows an example implementation of step 1204 of flowchart 1200 shown in FIG. 12. As shown in FIG. 15, each die 104 is released from support surface 404, and therefore remains attached to die plate 900. In an embodiment, for example, the adhesive force of adhesive material layer 1302 is stronger than the adhesive force of the bottom surface of support structure 404. Thus, when support structure 404 is moved away from die plate 900, dies 104 remain attached to die plate 900. Thus, support structure may be peeled from die plate 900 to transfer dies 104.
Note that although a vacuum source is not shown or used in FIGS. 13-15, in an alternative embodiment, a vacuum source can be used in the current embodiment to aid in transferring dies 104 to die plate 900.
In further embodiments, dies 104 of a wafer 400 can be directly transferred to die plate 900. FIG. 16 shows example steps related to a flowchart 1600 for transferring dies from a wafer to die plate 900, according to embodiments of the present invention. Further operational and structural embodiments of the present invention will be apparent to persons skilled in the relevant arts based on the following discussion.
FIGS. 17-19 relate to the steps of flowchart 1600 shown in FIG. 16. For example, FIG. 17 shows an example wafer having a plurality of dies included therein, being positioned adjacent to a die plate 900. Note that in an embodiment, wafer 400 has been thinned so that it has a thickness of approximately the thickness of a die. Furthermore, as shown in FIG. 17, an adhesive material layer 1302 has been applied to the top surface of die plate 900. Note that additionally, or alternatively, an adhesive material may be applied to the bottom surface of wafer 400.
FIG. 18 shows an example implementation of step 1602 of flowchart 1600 shown in FIG. 16. As shown in FIG. 18, wafer 400 and die plate 900 are positioned closely adjacent to each other such that wafer 400 adheres to the first surface of die plate 900. Note that die plate 900 and wafer 400 are positioned such that each die 104 of wafer 400 covers a corresponding hole 906 through die plate 900 at the first or top surface of die plate 900.
FIG. 19 shows an example implementation of step 1604 of flowchart 1600 shown in FIG. 16. As shown in FIG. 19, each of dies 104 are scribed/separated from wafer 400 so that they remain attached to the top surface of die plate 900. For example, as shown in FIGS. 18 and 19, a saw mechanism 1802 can be used to separate the dies 104 of wafer 400. The blade of saw mechanism 1802 may track the grooves or lines of grid 1002 which can be optionally formed in the top surface of die plate 900. Saw mechanism 1802 can be a saw blade or other cutting device, can be a laser, or any other sawing or cutting device suitable for separating dies from a wafer 400.
2.1.1.1 Die Transfer onto a Die Plate from Partially Cut Adhesive Surface
FIGS. 20-26 show various views of a transfer of dies to a die plate, and subsequently to one or more substrates, according to embodiments of the present invention. FIG. 20 shows a wafer 400 attached in a pads-up fashion to a surface of a support structure 404. For example, wafer 400 and support structure 400 may be held in a conventional wafer frame or other holding mechanism. As shown in FIG. 20, a first die 104 is being separated from wafer 400. For example, as shown in FIG. 20, a saw mechanism 1802 (or other suitable device or process) can be used to scribe/separate die 104 of wafer 400. Furthermore, saw mechanism 1802 penetrates and cuts/separates a groove depth 2002 of the total thickness 2004 of support structure 404 when separating first die 104 a from wafer 400, to form grooves 2006. Groove depth 2002 can be any portion of the thickness 2004 of support structure 404, as required by the particular application. As shown in FIG. 20, groove depth 2002 can be greater than 50% of thickness 2004, including approximately 90% of thickness 2004.
Note that although FIG. 20 shows dies 104 being separated when grooves 2006 are formed, in another embodiment, dies 104 may already have been separated before grooves 2006 are formed. Thus, in such an embodiment, grooves 2006 may be formed in a subsequent processing step to the actual scribing of wafer 400. Thus, the present application is applicable to using scribed and un-scribed wafers.
FIG. 21 shows wafer 400 having a plurality of dies 104 a-d separated, with grooves 2006 a-e formed in support structure 404 around each of the plurality of dies 104. Furthermore, FIG. 21 shows wafer 400 being positioned adjacent to a die plate 900 in preparation for transfer of dies 104 to die plate 900. Note that because grooves 2006 penetrate support structure 404 around each die 104, potentially weakening support structure 404, support structure 404 may sag when being positioned adjacent to die plate 900. Such sagging of support structure 404 may create difficulties in precisely aligning dies 104 over corresponding holes 906 through die plate 900. Thus, if groove depth 2002 is great enough to cause significant sagging of support structure 404, a vacuum and/or positive pressure may be used to reduce or eliminate the sagging. For example, FIG. 22 shows a pressure source 2202 used to provide a positive pressure. For example pressure source 2202 provides a gas pressure 2204 directed through holes 906 of die plate 900 to reduce sag in support structure 404 when support structure 404 and die plate 900 are being moved into contact. Alternatively or additionally, a vacuum source may be applied to support structure 404 (e.g., from above support structure 404 in FIG. 22) to provide a vacuum/suction to reduce sag in support structure 404.
FIG. 23 shows support structure 404 and die plate 900 positioned closely adjacent to each other such that support structure 404 adheres to the first surface of die plate 900. Note that die plate 900 and wafer 400 are positioned such that each of dies 104 a-d covers a corresponding hole 906 a-d through die plate 900 at the first or top surface of die plate 900.
FIG. 24 shows a close up view of a die 104 a of FIG. 23, where die plate 900 attaching support structure 404 and dies 104 has been inverted. As shown in FIG. 24, a pin 2402 is inserted in hole 906 a to be used to push/punch die 104 a from die plate 900. FIG. 25 shows pin 2402 moving through hole 906 a of die plate 900 to contact support structure 404 opposite of die 104 a, to push die 104 a in contact with a substrate 2502. Pin 2402 separates die 104 a from support structure 404 by tearing/ripping support structure 404 around the perimeter of die 104 a, such as at perimeter portions 2504 a and 2504 b in FIG. 24 (an adhesiveness of substrate 2502 may also contribute to this tearing/ripping of support structure 404).
Note that pin 2402 may be coupled to a pin plate having a plurality of pins 2402 that push/punch a plurality of dies 104 from die plate 900 in parallel onto the same or multiple substrates. For example, in a multiple substrate embodiment, the substrates may be separate, or joined together in a web of substrates. For further information on example pin plates, refer to co-pending U.S. application Ser. No. ______, titled “Method, System, And Apparatus For Transfer Of Dies Using A Pin Plate,” having the same filing date as the present application, which is incorporated by reference in its entirety herein.
FIG. 26 shows die 104 a on substrate 2502, having been separated from support structure 404 by pin 2402. As shown in FIG. 26 portion 2602 of support structure 404 remains attached to die 104 a. Portion 2602 of support structure 404 helps to protect die 104 a from damage due to pin 2402 during transfer of die 104 to substrate 2502. Portion 2602 attached to die 104 a can subsequently be removed from die 104 a if desired, or can remain on die 104 a when the respective tag or other device including substrate 2502 is completed. For example, portion 2602 can remain on die 104 a to provide environmental protection for die 104 a.
FIG. 27 shows a flowchart providing steps for transferring dies, according to embodiments of the present invention. For example, FIG. 27 relates to the transfer of dies shown in FIGS. 20-26. Further structural embodiments of the present invention will be apparent to persons skilled in the relevant art(s) based on the following discussion. These steps are described in detail below.
In step 2702, grooves are formed in a first surface of a support structure that attaches a plurality of dies. For example, the grooves are grooves 2006 formed in support structure 404, as shown in FIGS. 20-25. Note that the dies attached to the support structure may be separate on the support structure, or included in a wafer, prior to formation of the grooves.
In step 2704, a second surface of the support structure and a die plate are moved into contact with each other so that the support structure attaches to the die plate. For example, as shown in FIG. 23, the bottom surface of support structure 404 is moved into contact with die plate 900, to become attached to die plate 900. Note that in an embodiment, as described above, a positive pressure can be applied to the support structure to reduce sag in the support structure.
In an embodiment, flowchart 2700 includes step 2706. In step 2706, at least one hole through the die plate is punched through to transfer a corresponding die from the die plate to a destination surface. For example, as shown in FIGS. 24 and 25, pin 2402 passes through hole 906 a to transfer die 104 a from die plate 900 to substrate 2502. Note that in an embodiment, the support structure around the corresponding die is torn to release the die from the support structure. In an embodiment, a portion of the support structure remains attached to the die.
2.1.2 Example Die Plate Embodiments
As described above, FIGS. 10A-E show example schematic views of die plate 900, according to an illustrative embodiment of the present invention. As described above, a die plate can be made from a variety of materials. In an embodiment, a die plate is made from the same material as a corresponding pin plate is made, or from a material having the same coefficient of thermal expansion (CTE) as a corresponding pin plate, so that the die plate and pin plate will expand and contract uniformly due to changes in temperature. For example, a die plate and corresponding pin plate can be from aluminum. In another example, one of the die plate and corresponding pin plate are made from Kapton, while the other is made from aluminum, because Kapton and aluminum have very similar CTE values. Alternatively, both can be made from Kapton.
As described above, FIG. 10A shows a die plate 900, and shows the outline of a wafer 400 superimposed on top of die plate 900. Die plate 900 can have any shape and size, as required by a particular application. For example, die plate 900 shown in FIG. 10A can have a width and length of approximately 254 mm. Wafer 400 can have a diameter of approximately 203 mm, for example. Die plate 900 can have holes 906 spaced according to any distances, as required by a particular application. For example, in one embodiment, die plate 900 can have a hole pattern of 103×205 holes spaced apart 2 mm horizontally and 1 mm vertically for a total number of 21,115 holes (e.g., for rectangular die). Such a pattern can cover a 204 mm×204 mm pattern (from hole center to hole center).
FIG. 10C shows a plan view of a die plate portion 1020. Holes 906 can have any diameter, as required by a particular application. Typically, holes 906 have a diameter less than or equal to a minimum of the width and length of a corresponding die. For example, hole 906 shown in FIG. 10C can have a diameter of approximately 0.584 mm to accommodate a die having a width of approximately 0.949 mm and a length of approximately 1.949 mm. FIGS. 10D and 10E show cross-sectional views of portions of die plate 900. Grooves 1002 can have any widths and depths, as required by a particular application. For example, grooves 1002 shown in FIGS. 10D and 10E can have widths of approximately 0.051 mm and depths of approximately 0.051 mm.
It is noted that any of the sizes/dimensions, spacings, numbers of holes, etc., described above are provided for illustrative purposes. It will be apparent to persons skilled in the relevant art(s) that these parameters can be modified as needed for a particular application. For example, these parameters can be modified for particular wafer sizes, die sizes, number of dies to be transferred in parallel, etc.

CONCLUSION

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant arts that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. A method for transferring a plurality of integrated circuit dies that are attached to a support structure to a die plate, comprising:

(a) positioning the support structure and die plate to be closely adjacent to each other such that each die of a plurality of dies attached to the support structure adheres to a first surface of the die plate due to an adhesive material; and

(b) releasing each die of the plurality of dies from the support structure so that each die remains attached to the die plate.

2. The method of claim 1, wherein step (b) comprises:

moving apart the support structure and die plate.

3. The method of claim 2, wherein said moving step comprises:

moving apart the support structure and die plate so that each die remains attached to the die plate due to the adhesive material overcoming an adhesiveness of the support structure.

4. The method of claim 2, wherein step (a) comprises:

positioning the support structure and die plate to be closely adjacent to each other such that each die of the plurality of dies covers a corresponding hole through the die plate, wherein each hole is open at the first surface and second surface of the die plate.

5. The method of claim 4, further comprising:

(c) applying a suction at a second surface of the die plate that further adheres each die to the die plate due to the corresponding hole.

6. The method of claim 1, further comprising:

(c) applying the adhesive material to the first surface of the die plate.

7. The method of claim 1, wherein a first surface of each die is attached to the support structure, further comprising:

(c) applying the adhesive material to a second surface of each die of the plurality of dies.

8. The method of claim 2, wherein the support structure is a tape structure, wherein said moving step comprises:

peeling the support structure from the die plate.

9. A method for transferring a plurality of integrated circuit dies from a wafer to a die plate, comprising:

(a) positioning the wafer and die plate to be closely adjacent to each other such that the wafer adheres to a first surface of the die plate due to an adhesive material, wherein the die plate includes a plurality of holes, wherein each hole is open at the first surface and a second surface of the die plate, wherein each die of a plurality of dies of the wafer covers a corresponding hole through the die plate; and

(b) separating each die of the plurality of dies from the wafer so that each die remains on the die plate.

10. The method of claim 9, wherein step (b) comprises:

sawing each die of the plurality of dies from the wafer.

11. The method of claim 10, wherein said sawing step comprising:

sawing along grooves in the first surface of the die plate that are positioned at boundaries between adjacent dies of the plurality of dies of the wafer.

12. The method of claim 9, further comprising:

(c) applying a suction at a second surface of the die plate that further adheres the wafer to the die plate due to the plurality of holes.

13. The method of claim 9, further comprising:

(c) applying the adhesive material to the first surface of the die plate.

14. The method of claim 9, further comprising:

(c) applying the adhesive material to a surface of the wafer.

15. The method of claim 9 wherein step (b) comprises:

using a laser to separate each die of the plurality of dies from the wafer.

16. A method for transferring a plurality of integrated circuit dies, comprising:

(a) forming grooves in a first surface of a support structure that attaches a plurality of dies, wherein the grooves are formed in the surface of the support structure between the dies; and

(b) moving a second surface of the support structure and a die plate into contact with each other so that the support structure attaches to the die plate, and so that a portion of the support structure attaching each die of the plurality of dies covers a corresponding hole through the die plate.

17. The method of claim 16, wherein the plurality of dies are included in a wafer, wherein step (a) comprises:

cutting through the wafer to separate the dies from the wafer and to form the grooves in the surface of the support structure.

18. The method of claim 16, wherein the plurality of dies are separate on the support structure, wherein step (a) comprises:

forming the grooves in the surface of the support structure through channels between the dies.

19. The method of claim 16, further comprising:

(c) applying a positive pressure to the support structure to reduce sag in the support structure.

20. The method of claim 16, further comprising:

(c) punching through at least one hole through the die plate to transfer a corresponding die from the die plate to a destination surface.

21. The method of claim 20, wherein step (c) comprises:

tearing the support structure around the corresponding die to release the die from the support structure, wherein a portion of the support structure remains attached to the die.