Multiple-module chip manufacturing arrangement

Abstract

To provide assemblies and subassembly modules for manufacture of wafer chips or substrates with solder balls or plated solder balls.SOLUTION: A wafer tool assembly (10) comprises a large number of modules (12-20). The large number of modules (12-20) are connected to one another and all operated by a robotic arm (22) in order to transfer processed wafers (W) from one module to another. The tool assembly comprises a load port (12), a pre-aligner module (14), a binder module (16), a solder ball mount module (18), and a reflow module (20). A wafer inspection (24) and repair module arrangement are also parts of the tool assembly.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001]

[0001] The present invention relates to assemblies and subassembly modules for manufacturing wafer chips or substrates with solder balls or plated solder balls (also called bumps attached to the wafer chip or substrate), and more particularly to devices for processing wafers with fluxless or flux-free binders in a connectable configuration of processing modules that can be interconnected and adapted to change the conditions of such wafer chip manufacturing. For the purposes of this discussion, to avoid confusion, plated solder balls, solder balls, bumps and the like are all designated as "solder balls." Summary of the Invention

[0002]

[0002] The present invention relates to a system for manufacturing wafer chips having solder balls disposed thereon, comprising an arrangement of individual modules taken together, each of which is designed to facilitate efficient manufacture of its component of the chip assembly required for completion.

[0003] For marketing purposes, the assembly may be referred to herein by the trademark name "Symphony" chip assembly configuration or tool.

[0004]

[0004] The Symphony chip assembly tool includes a front-end module (EFEM), a binder application module, a solder ball mount module (SBM), an inspection and repair module, and a reflow module. The front-end module includes a robot arm for moving wafers between the modules, and a pre-aligner for the wafer placement process. Further embodiments of the Symphony tool assembly include a side-by-side configuration of multiple reflow modules. Also, the front-end module (EFEM) can be positioned adjacent to multiple reflow modules so that their operations can be performed in parallel to increase the throughput of the reflow process. Furthermore, further embodiments of the Symphony assembly include a dual solder ball mount module configuration configured to increase the throughput of the ball mount step. Such a further dual solder ball mount configuration includes a front-end module (EFEM), two solder ball mount (SBM) modules for adjacent parallel processing, a binder application module, and an inspection module. Additionally, a further embodiment of the Symphony tool assembly includes a single reflow module configuration with its front-end module (EFEM) that services the single reflow module.

[0005]

[0005] The present invention therefore includes a unified wafer or chip assembly arrangement or tool for attaching solder balls onto a wafer substrate for subsequent use in the electronics industry, the wafer assembly arrangement including an arrangement of individual wafer processing modules interconnected to and operated by a central wafer handling robot, the arrangement including a pre-aligner module for receiving the wafer to be processed, a binder module for applying a fluid binder to the top surface of the wafer, a solder ball mounting module for attaching a number of solder balls onto the wafer, a reflow module for heating and fixing the solder balls onto an arrangement of pads on the wafer, and an inspection module having a review and analysis and, if necessary, repair arrangement for the solder balls deposited on the wafer. The fluid binder is applied to the wafer by a nozzle arrangement supported on a gantry movably positioned directly above the wafer supported thereunder. The number of solder balls are arranged in an array on the solder ball engagement locations of the separation pattern on the wafer after the solder balls are filtered through a vertical array of perforated solder ball alignment plates movably positioned above the wafer. The air knife is driven laterally relative to the array of solder balls on the surface of the wafer such that any stray solder balls are pushed away from the surface of the wafer, where they are transferred to a unidirectional channel for collection and subsequent reuse on additional wafers.

[0006]

[0006] The present invention also includes a process for manufacturing chip assemblies in a unified wafer assembly system for use in the electronics industry, the process comprising the steps of: removing a wafer from a front opening by a robot, where the wafer is transported to a pre-aligner for centering; transferring the wafer by the robot to a binder station, where a binder fluid is applied to the wafer; carrying the wafer by the robot onto a chuck of a first wafer handling position opening of a solder ball mount station; aligning the wafer by a camera arrangement for subsequent orientation of the wafer using the stencil hole pattern; transferring the wafer to a second wafer handling position opening where the stencil is present; moving the wafer support chuck upward to lift the wafer close to the stencil, i.e., a distance less than the diameter of a solder ball; and verifying by a camera verification arrangement on an overhead solder ball head as part of a movable gantry to identify fiducial marks on the wafer. verifying wafer alignment by viewing the wafer through the stencil; once wafer alignment is verified, moving the solder ball head to the appropriate position directly over the wafer; dispensing solder balls from a solder ball reservoir on the solder ball head through a funnel to a distribution cup and then to a distribution plate, allowing them to fall through a number of perforated plates; dropping the solder balls onto the perforated stencil; bringing the solder ball head close to the stencil; actuating the solder ball head so that the brush is directly over the stencil; moving the brush back and forth across the wafer without touching the wafer to force the solder balls into the remaining holes in the wafer; blowing compressed dry air across the stencil with an air knife on the gantry to collect unmounted solder balls in a vacuum compatible collection chamber for subsequent reuse; and lowering the chuck and wafer in the solder ball mount module for pick-up by the robot.The method includes the steps of: transporting the solder ball-loaded wafer to a solder ball inspection and / or repair station; transporting the solder ball-loaded wafer to a chuck of the input lock station / first chamber of the reflow module by a robot and purging oxygen from the first station; holding the wafer on the chuck by vacuum and rotating the chuck forward to the second station for preheating; raising the wafer position through the chuck on an elevator to a top ring of the chamber of the second station to reach a maximum reflow temperature before melting; lowering the wafer position through the chuck by the elevator to return it to the wafer while it is on the chuck so that it can reach a controlled reflow temperature, which is then rotated to the third station of the reflow module; releasing the wafer from the chuck by a vacuum plate, where the wafer is cooled by nitrogen below the plate and above the wafer and where a vacuum is drawn through the chuck to hold the wafer horizontally flat on it; and rotating the chuck back to the first station for removal of the finished wafer. ,

[0007]

[0001] The objects and advantages of the present invention will become more apparent when viewed in conjunction with the following drawings. [Brief description of the drawings]

[0008] [Figure 1] FIG. 3 is a schematic plan view of an assembly tool configuration, also showing a robot arm configuration for transferring wafers from station to station within the assembly tool assembly. [Diagram 2] FIG. 4 is a perspective view of a binder module for applying binder fluid to a wafer under construction. [Diagram 3] FIG. 6B is a partial side elevational view of the binder coating chamber shown in FIG. 6A. [Figure 4]FIG. 1 is a partial perspective view of a wafer support plate or chuck for lifting a wafer thereon into a binder coated enclosure. [Diagram 5] FIG. 7 is a perspective view of a solder ball mount module and associated optical inspection configuration showing a robotic arm for feeding wafers to the solder ball mount module. [Figure 6] FIG. 10 is a perspective view of the solder ball mount module shown in FIG. 9 with inspection optics and camera configuration showing the gantry configuration. [Figure 6A]

[0009] FIG. 1 is a side elevational view of the brush head showing the final or distribution of solder balls onto the main distribution plate and several auxiliary distribution plates below it, with a sweeper arrangement attached to the bottom of the brush head and a stencil shown directly below it spaced above a wafer supported on a chuck. [Figure 7]

[0010] FIG. 2 is a perspective view of the underside of the ball brush arrangement. [Figure 8A]

[0011] FIG. 1 is a perspective view of the inspection module of the assembly, which inspects the wafer to ensure that all solder balls are properly positioned on the wafer prior to reflow; a line scan camera located on top of the inspection module looks downward at the wafer on its support chuck to capture an image of the entire wafer for computer analysis. [Figure 8B]

[0011] A side elevation view of the inspection module of the assembly, which inspects the wafer to ensure that all solder balls are properly positioned on the wafer before reflow; a line scan camera located on the top of the inspection module looks downward at the wafer on its support chuck to capture an image of the entire wafer for computer analysis. [Figure 8C]

[0011] A side elevation view of the inspection module of the assembly, which inspects the wafer to ensure that all solder balls are properly positioned on the wafer before reflow; a line scan camera located on the top of the inspection module looks downward at the wafer on its support chuck to capture an image of the entire wafer for computer analysis. [Figure 8D]

[0012] FIG. 13 is a perspective exploded view of a repair station that complements the inspection module. [Figure 9]

[0013] FIG. 1 is a perspective view of a reflow module in an open state, including a chamber with three stations: a load lock station, a reflow station, and a warp management station, with wafers moved from station to station within the chamber by a rotating carrier disk. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009]

[0014] The present disclosure includes, in its general aspect, an apparatus and process for processing wafers for use in the electronics industry, in which: A wafer to be processed is removed from a raw wafer stack by a robotic arm; The wafer is transported to a pre-alignment station and centered on a carrier; The wafer is transferred to a station of an adjacent binder module; Binder fluid is applied to the wafer; The wafer is then removed by the robotic arm and sent to a solder ball mount station module; The wafer is aligned by a camera at a first support opening to orient the wafer along a line with the stencil hole pattern; The wafer is transferred to a second support opening solder ball mount module where the stencil is present; The chuck is moved upwards to support the wafer in close proximity directly under the stencil (the distance between the wafer and the stencil is less than the diameter of the solder balls). Solder balls are dropped from a reservoir in the solder ball mount module into a cup and perforated plate dispensing arrangement, the solder balls pass through the perforated plate arrangement and into holes in an alignment stencil onto the wafer directly below, the ball-mounted wafer is brushed and treated with compressed dry air to achieve solder ball placement and removal of excess solder balls from the wafer, and the wafer is transferred to a reflow station for final heat treatment and cooling of the solder ball-mounted wafer. Such process procedures are those recited as steps that the apparatus of the present invention performs to produce chips suitable for the electronics industry.

[0010]

[0015] Here, in particular, Fig. 1 Referring in detail to the drawing, there is shown a schematic representation of the configuration of a unified chip assembly tool 10. The chip assembly tool 10 includes a load port 12, a pre-aligner module 14, a binder module 16, a solder ball mount module 18, and a reflow module 20, each of which is serviced by sequential loading and unloading by a central robotic arm arrangement 22. The binder module is shown in FIG. 2 In this perspective view, 3 It is shown in side elevation in Fig.1 Also shown in FIG. 1 is an inspection module 24, which in addition to inspection may include disposing or repairing improperly loaded wafers. 8 This is disclosed in more detail in D.

[0011]

[0016] figure 1 Operation of the chip assembly tool 10 as shown in FIG. 1 begins at the load port where a wafer "W" is picked up from a Front Opening Unified Pod (FOUP) and transferred to the binder module 16. The effector of the robot arm 22 is shown in FIG. 3 As shown in FIG. 1, a wafer "W" is placed on support pins 30. These support pins 30 have vacuum cups at their tips, which are 4 1, the wafer "W" is held by the robot arm 22 after it has been placed on the vacuum support plate 32. 3 and Figure 4 1, the plate 32 is raised by actuation by a pneumatic actuator 34 to raise the wafer "W" into a binder application enclosure 36. The support pins 30 are embedded just below the surface of the support plate 32 and rise as the plate 32 is raised. As the support plate 32 rises, it engages the wafer "W" and holds the wafer "W" intimately to the support plate 32 by the vacuum drawn through the support plate 32. The support plate 32 has three independently controlled vacuum zones, each configured and defined by a series of vacuum channels 40, as shown in FIG. 4 In addition to holding the wafer W, the multi-zone design also allows the plate 32 to hold a warped wafer flat. When the support plate reaches the top of its stroke, it rotates to the left or right as shown in FIG. 4 4, which acts as a hard stop. The inner edge of the clamping ring 42 presses against the outer edge of the wafer W, forming a liquid-tight seal. 3By one or more nozzles 44 as shown in FIG. 3 , where the nozzle 44 scans the wafer "W" in one or more passes. The nozzle 44 evenly distributes the fluid binder "B" by spraying the fluid binder "B" in a fan pattern generally perpendicular to the scanning direction. 3 As shown in FIG. 1, the gantry 46 supports the gantry 46. The gantry motion is as shown in FIG. 5 After depositing Binder B, the air knife 50 is driven by a belt drive 48 via a computer controlled linear actuator as shown in FIG. 3 As shown in FIG. 1, the wafer is scanned and a curtain of compressed dry air is sprayed onto it. The force of the compressed dry air spreads, thereby thinning the deposited binder and leaving a uniform thin film on the wafer. The air knife 50 is mounted on the same gantry frame 46 as the nozzle 44, and although the scanning motions of the two systems are mechanically coupled, they are controlled independently of each other and can operate simultaneously or at different times. The air knife 50 also sweeps excess binder "B" away from the wafer. The excess binder is then removed by a vacuum pump 56, as shown in FIG. 1. 3 As shown in FIG. 1, the binder flows across the clamp ring 42 through a channel 52 at the top of the ring 42 and down into a collection container 54. The binder flows out on one side to a drain port connected to a collector and excess binder is stored for eventual reuse. After binder application, the vacuum support chuck 56 is lowered, the vacuum is released on the clamp and support pins, and the robot 22 removes the wafer "W" from the binder module 16. The height, spacing, and angle of the binder dispense nozzles can be manually adjusted. Different lengths and spacings can be used to optimize the binder dispense pattern. The height and angle of the air knife 50 can also be manually adjusted. The volume of binder dispensed is controlled by the dispense time, the reservoir tank pressure, and a manual knob on the nozzle itself. The flow rate of compressed dry air through the air knife 50 is controlled by the dispense time, the reservoir tank pressure, and a manual knob on the nozzle itself, as shown in FIG. 1The flow rate is controlled by a combination of mass flow controllers and orifices in the fixture panel 60 as shown in FIG. Bringing the air knife 50 closer to the surface of the wafer "W" concentrates the force of the air curtain, which generally results in a thinner binder film. The air knife 50 is also used to clean wafers that exhibit missing or misaligned solder balls; such wafers are subjected to the same pressure as shown in FIG. 8 Repair is required at repair station 198 as shown at D. The air knife 50 blows all the solder balls SB of excess binder off the wafer "W". The binder enclosure 36 is evacuated to prevent any remaining binder material from escaping by airborne transfer and contaminating the parts of the tool assembly.

[0012]

[0017] The operation of the chip assembly tool 10 is shown in FIG. 1 and Figure 5 This is followed by removal of the solder ball-loaded wafer "W" by the robot arm 22 shown in FIG. 1, where the solder ball-loaded wafer "W" is roughly aligned in the pre-aligner of the loading port 12. The solder ball-loaded wafer "W" is then 8 ,figure 9 and Figure 10 As shown in FIG. 1, the wafer W is transferred to the solder ball mount module 18 for optical alignment of the solder balls on the wafer W. The wafer vacuum support chuck starts at a loading position where it receives the wafer from the robot arm 22. The wafer plate has support pins with vacuum cups and a set of several independently controlled vacuum channels or zones on the surface of the support plate. The wafer "W" is first loaded onto the support pins and secured with the vacuum cups. The pins are recessed into the vacuum support chuck. This lowers the wafer to the chuck surface where it is held by the vacuum zones. FIG. 5As shown in Figure 1, the stage is actuated in the X, Y, and Z directions by precision ball screws pressed by linear actuators. A precision turntable also rotates the wafer "W" on the beta stage. All wafer support movements are computer controlled through appropriate circuitry. The wafer stage is then rotated as shown in Figure 1. 5 The wafer is then moved into the alignment window cutout 70 in the upper mounting plate 66 as shown in FIG. 5 and 6 Two downward looking cameras 60, 62 shown in are positioned above the wafer "W" such that each camera views a different predefined location on the wafer. Each camera 60, 62 is mounted on an independently operating linear drive 64 in a transverse orientation relative to a mounting plate 66. Both actuators are shown in FIG. 5 and 6 The stages are in turn mounted on a gantry frame 74 shown in FIG. 1 which can be actuated along the longitudinal axis of the mounting plate using one or two precision ball screw actuators. Each camera 60, 62 takes an image of a small portion of the wafer "W" and a suitable computer (not shown) uses this information to determine the exact location of the wafer in an X, Y, Theta configuration. The stages are shown in FIG. 5 The vertical and horizontal movement of the wafer is accomplished through a second stencil window 78 in the mounting plate as shown in FIG. The Z movement of the stage raises the position of the wafer "W" so that the top surface of the wafer "W" just touches or is slightly below the bottom surface of the stencil 80. The computer control system already knows the exact orientation of the stencil 80 and, combined with knowledge of the orientation of the wafer, can position the wafer so that it is aligned with the stencil 80 with great precision before being separated in the Z direction. 6 A verification camera 82, shown in FIG. 1, is configured to verify the final placement of the wafer "W" relative to the stencil 80. 6Using a pneumatic actuator 86, represented in FIG. 1, the verification camera 82 moves downward to focus on the stencil 80 and wafer "W." The verification camera 82 moves upward to get a clear view of the subsequent movement of the ball mount head 90.

[0013]

[0018] Operation of the chip assembly tool continues and the solder ball mount head moves to a position directly above stencil 80 and then lowers to a dispensing position, making only slight contact with stencil 80. 7 The rotating floater 88 shown in FIG. 1 tilts the reservoir 102 and releases a predetermined volume of solder balls SB onto the primary distribution plate. The solder balls SB then travel downward through holes in several levels of the auxiliary distribution plate for further spreading before finally being distributed across the surface of the stencil 80. 7 The brush head 96 depicted in FIG. 1 is driven by a pneumatic actuator 98. The brush head 96 includes a series of sweeping members 100 (such as wires, pressurized perforated tubes drilled along their undersides, or the like) and is shown in FIG. 7 The sweep members 100 shown in FIG. 1 reach down to the underside of the brush head 96, protruding downward and slightly touching it. If the sweep members 100 are wires, they are placed under slight tension so that the portion of each wire shown is drawn in a straight line parallel to the surface of the stencil 80. The straight portion of each sweep member wire 100 spans a distance greater than the diameter of the wafer "W" being processed. By maintaining the wires 100 parallel to the stencil surface, uniform spacing between the wires 100 and the stencil 80 can be ensured. The gap between the stencil wires, if any, can be controlled to hold the solder balls SB between each pair of wires such that the solder balls SB cannot pass freely underneath. Once the brush head 96 is lowered, FIG. 7A computer-controlled electromagnetic vibrator 102, shown in FIG. 1, drives the brush head 96 with a small oscillatory motion parallel to the plane of the stencil 80 and perpendicular to the axis of the wire or tube 100. The small amplitude oscillatory motion is designed to move the solder balls SB over small distances between the wire or pressurized air tube 100 without damaging the stencil 80. During vibration, the brush head 96 also translates back and forth parallel to the stencil 80 and perpendicular to the wire or tube 100 with limited overall motion to ensure that no point on the stencil 80 is swept by the vibrating wire or pressurized tube 100. The translation of the sweeping member wire or pressurized tube 100 also ensures that the holes in the stencil 80 are not blocked during the entire time of the spreading action, thereby preventing the solder balls from filling those blocked holes. After spreading the solder balls SB, each hole in the stencil 80 should contain one solder ball SB, so that when the wafer and stencil are separated from each other, one solder ball SB remains on the pad on the wafer. There may be extra solder balls SB on the stencil 80 that did not fill the holes, and these extra or excess solder balls need to be removed before the wafer is lowered. The brush head 96 moves up and down out of the way, as shown in FIG. 3 The air knife 50 shown in Figure 1 sweeps the stencil 80, pushing all excess solder balls SB to the rear of the stencil 80. The air flow from the air knife 50 is strong enough to push away all solder balls that did not stay in the holes, but not strong enough to knock off the deposited solder balls. The air knife 50 pushes the balls under a flap, which acts as a one-way gate to prevent the solder balls from being pushed back into the stencil 80. The solder balls are collected at the rear edge of the stencil 80 and are sucked up by an overhead vacuum duct. From there, the solder balls are transported to a collection container where all the solder balls are separated from the airflow and stored for later reuse.

[0014]

[0019] figure 6At A there is shown a schematic representation of the brush head 21 and solder ball mount module 18, showing a funnel 23 which drops solder balls SB onto a perforated primary distribution plate 25 through which they drop onto auxiliary distribution plates 27, 29. Directly below the auxiliary distribution plates 27, 29 is shown a perforated stencil 31. The stencil 31 is shown above a wafer "W" which is positioned on a support chuck 33, on which pads 35 are disposed. A sweeper arrangement 37 is shown generally as attached to the shared brush 21.

[0015]

[0020] Different processes can use solder balls of different sizes and compositions, therefore it is very important to avoid cross contamination. Each type of solder ball has its own reservoir, brush and collection container. These components can be mechanically and / or electronically matched so that components for use with different solder balls cannot be mixed.

[0016]

[0021] First, the figure 1 Inspection module 24, shown in FIG. 2, is utilized to inspect wafer "W" after ball placement to ensure all solder balls are properly positioned prior to reflow. Robot 22 is shown in FIG. 8 A wafer "W" on which solder balls SB as shown in A are mounted is 8 The wafer is then loaded onto the support pin arrangement 106 having a vacuum cup thereon as shown in FIG. B. Once the pin arrangement 106 supports the wafer "W", they are moved downward by actuation by a pneumatic actuator, and the wafer is then loaded onto the support pin arrangement 106 having a vacuum cup thereon as shown in FIG. 8 As shown in FIG. 1B, the support pins are recessed into a vacuum support plate 108. The support plate 108 contains several sets of independently controlled vacuum channels or zones that pick up the wafer when the support pins are lowered. 8 The line scan camera 110 shown in FIG. 8The wafer is viewed downward as shown in FIG. A. The support chuck and wafer are translated across the field of view of the linescan camera 110 to capture an image of the entire wafer "W". The support chuck is actuated by a computer controlled precision ball screw and can be illuminated by an artificial light source arrangement. The wafer image is automatically analyzed to identify defects such as missing solder balls, extra solder balls or solder balls that are misaligned with respect to the wafer. Those wafers that pass inspection proceed to the reflow module while those that fail inspection are repaired or stored in a buffer station for later rework.

[0017]

[0022] Such a repair station 198 is shown in FIG. 8The equipment panel 212 is shown in FIG. 1D and includes a base frame 210 supporting a control panel 212, a number of controls 214, a granite inspection slab 216 mounted on the base frame 210, a pick and place arm 220 mounted for movement in an X direction, a scanner drive assembly chuck 222 positioned on the granite inspection slab 216 for movement in a Y direction, and an inspection camera assembly 200. The inspection light assembly 202 is shown in the up position directly above the scanner drive assembly chuck 222. When in the down position, the inspection light assembly 202 provides light that allows the inspection camera assembly 200 to view the wafer W on the scanner drive assembly chuck 222. The scanner drive assembly 222 moves the wafer below the camera assembly 200, allowing an image of the entire wafer to be generated. The locations of missing solder balls and the locations of extra or misplaced solder balls are identified from this image and the coordinates are written into a control computer system associated with the equipment panel 212. The inspection light 202 can be moved to an up position, which allows the pick and place arm 222 to move directly above the wafer W on the scanner drive assembly chuck 222. The pick and place assembly as a needle hub configuration 230 including a vacuum configuration. While the pick and place assembly 220 remains directly above the wafer, the pick and place assembly 220 removes any misplaced solder balls and disposes of them.

[0018]

[0023] The inspection light 202 is moved to an up position, which allows the pick and place assembly 220 to move close to and directly above the wafer W. By staying directly above the wafer, the pick and place assembly 220 can be utilized to replace the wafer. First, the pick and place assembly 220 removes the misplaced solder balls and disposes of them. Next, the pick and place assembly 220 attaches and adds to the wafer any solder balls that have been determined to be missing. The pick and place assembly 220 can reach any location on the wafer by utilizing linear X and Y actuation movements. In between these functions, the pick and place camera 200 mounted between the actuators can be used to directly verify the placement or removal of a single solder ball. This verification is important during testing. Once the wafer is repaired, the pick and place assembly 220 can be used to directly verify the placement or removal of a single solder ball. 8 As shown in FIG. 1D, the wafer is moved to the left out of the way. Finally, the inspection light assembly 202 moves down to allow the inspection camera 200 and scanner drive 222 to create a second image of the wafer. If no errors are found, the wafer is removed from the inspection station and transferred to the reflow module and another wafer can be brought in for repair.

[0019]

[0024] The reflow module 20 (having its own reference number) shown and discussed extensively in co-pending patent application Ser. No. 15 / 998,295, which is incorporated herein by reference and in which: 9 As shown in FIG. 1, it consists of an open chamber 120 and is currently shown to have three stations: a load lock or first station 122, a reflow or second station 124, and a warp management station 126. 9The diagram in FIG. 1 shows the reflow module in an open state. During processing, the chamber is closed and sealed to the ambient environment. Wafers are moved from station to station within the chamber by a rotating carrier disk 128. The disk 128 has multiple slots for sequential wafer processing. Each slot is shown in FIG. 4 and similarly, the carrier ring as shown in FIG. 4 The wafer is placed in a support ring as shown in FIG. 4 A clamp ring, shown in FIG. 2, can also be used, which holds the wafer horizontally flat during processing and in the reflow chamber 20. While the wafer is in the reflow chamber, the outer edge of the wafer is sandwiched between the clamp rings of the support ring, forming a temporary annular hold-down.

[0020]

[0025] The load lock or first station 122 of the reflow module 20 receives a new wafer and the load lock vacuum support chuck and base plate are raised together by actuating the main pneumatic cylinder. The mechanism pulls the clamp ring away from the support ring to an upward position. The secondary pneumatic ring is actuated to lower the support plate relative to the base plate, thus exposing the support. The load lock door is opened by a pneumatic actuator, which translates and lifts the door. The wafer is loaded by the robot and is picked up by the vacuum cups on the tips of the support pins. The vacuum support chuck is raised to engage the wafer. The previously described vacuum zone on the chuck is activated to hold the wafer horizontally flat. The lowering mechanism lowers the clamp ring and locks it to the support ring. The mechanism can also provide additional downward force on the clamp ring to assist in horizontally flattening the wafer. This additional downward force may be necessary in cases where the vacuum is not sufficient to horizontally flatten the wafer. When the base plate is raised with the load lock door closed, a sealed mini-chamber is created. After the wafer is loaded, the chamber is purged with nitrogen to create an oxygen-free atmosphere. The support chuck is the base plate, and no oxygen is introduced into the rest of the chamber. This motion also returns the wafer to its position at the carrier disk.

[0021]

[0026] The reflow station or second station 124 of the reflow module 20 includes three computer controlled heating elements, as shown in FIG. 9, a bottom heater, a top heater, and a ring heater are shown. The main purpose of the bottom heater is to conductively heat the wafer "W" by direct contact with the wafer assembly, which consists of the wafer, support ring, and clamp ring. The top heater is used to further stepwise convectively heat the wafer in the tower, which is part of the reflow station above the desk. The ring heater is used to prevent edge heat loss and improve temperature uniformity of the wafer. A temperature gradient exists between the top heater and the bottom heater. The wafer can be positioned at different heights in the tower, which can be controlled to determine its rate of convective heating (i.e., temperature). The hot wall conducts heat from the top heater of the ring heater, creating a more stable and stepwise temperature gradient in the tower. The hot wall portion can be the same part that supports and transfers heat from the top heater.

[0022]

[0027] After the wafer is indexed from the loading lock to the reflow station, it must be preheated. Preheating is most effectively accomplished by convectively heating the wafer in the tower in close proximity to the top heater. The top heater can be set to any temperature, but is usually set much higher than the bottom heater. Thus, the higher the wafer is positioned in the reflow station, the hotter its environment is and the faster it heats up. Lift pins driven by servo motors lift the wafer assembly and control its height. Temperature sensors in the support ring contact the wafer and accurately monitor its temperature in real time. By combining wafer temperature monitoring with wafer height control, the user has excellent control over the temperature profile of the wafer. In the highest position, the support ring contacts a hard stop mounted on the top heater. The stop prevents the wafer assembly from directly contacting the top of the tower, preventing damage to both the tool and the wafer. The stop also conducts heat from the top heater to the support ring, which heats up and quickly lowers the convection heater. The much larger thermal mass allows the temperature difference between the support ring and fasteners and the wafer itself to increase, reducing the wafer temperature uniformity. Convectively heating the support ring minimizes the difference in heating rate between the wafer and the support ring, improving the wafer temperature uniformity. After preheating, the lift pins move the wafer assembly back to the desk position. The lower heater is then raised by the pneumatic member and contacts the bottom of the wafer, and the support ring, which is in direct contact with the wafer, quickly raises the wafer to the uniform research temperature. At this temperature, the solder balls on the wafer melt and attach to their respective pads on the wafer. The wafer is held by the vacuum channels of the lower heater, which can apply a vacuum force to the wafer as needed. The vacuum helps to hold the warped wafer horizontally flat, improving the conductive heating of the wafer in terms of both speed and uniformity. After a period of contact with the wafer, the lower heater is lowered on the wafer and indexed to the next station.

[0023]

[0028] As the wafer temperature rises, even before reflow, the solder balls stick to their pads on the wafer, causing metal diffusion between the solder balls and the pads, unnecessarily melting the binder. The liquid binder starts to evaporate at high temperatures, and by the time the wafer leaves the reflow station, all the binder has evaporated. To facilitate oxide removal and solder reflow, the reflow station, along with the rest of the chamber, maintains an oxygen-free reducing atmosphere. The atmosphere is a mixture of nitrogen gas and a reducing gas (such as formic acid). After the reflow station itself, a reducing gas mixture is introduced through holes in the side of the hot wall, plus binder vapors are exhausted through holes in the top of the tower, eventually making their way towards the reflow station exhaust. Between the reflow station exhaust of the main tool exhaust, a binder condensation system can be placed in line. This condensation system condenses the binder vapor, removes it from the exhaust flow, and prevents it from reaching the exhaust system of the facility.

[0024]

[0029] figure 91 shows the warp management station 126 (i.e., the third station of the reflow module 20), where the wafer and wafer assembly are maintained at a temperature above that of the heater and vacuum plate. It starts by placing the vacuum plate on the heater so that both are at the same temperature. The plate and heater are each actuated by their own pneumatic cylinder. The plate and heater first move together to contact the wafer. This allows the wafer to cool quickly and uniformly below the solder solidification temperature. Similar to a vacuum support chuck, the three vacuum zones of the plate can apply a vacuum force to the wafer and hold it horizontally flat. This improves the wafer-to-plate conduction, especially if the wafer has a tendency to bow. The plate is then separated and maintains its back grip on the wafer. Now, nitrogen gas is flowed into the channels above the plate to actively cool it. The cooling rate can be adjusted by varying the nitrogen flow with a mass flow controller. By maintaining contact between the wafer and the plate during cooling, instead of convectively cooling the wafer while it is free floating in the chamber, residual stresses on the wafer are minimized and even eliminated. This reduces wafer warping when the wafer is later released from the ring clamp. A nitrogen showerhead above the wafer can also convectively cool the wafer with impinging jets of nitrogen gas. After the plate / wafer system has cooled sufficiently, the vacuum is released and the plate is separated from the wafer. The wafer is now cooled only through convection until it leaves the station. While the wafer is cooling, the plate is lowered and re-contacted with the heater. This heats the plate to the starting temperature in preparation for the next wafer.

[0025]

[0030] Although the pneumatic members are independently controlled, the resulting plate and heater motions are coupled within a limited range. The wafer pneumatic members govern the absolute position of the heater with its own up and down position relative to the chamber. The plate pneumatics can effectively be thought of as a plate / heater separator. The plate pneumatics does not control the absolute position of the plate, but rather dictates whether the plate is up or in contact with the heater.

Claims

1. 1. A unified wafer assembly arrangement for depositing solder balls onto a wafer substrate for subsequent use in the electronics industry, the wafer assembly arrangement including a wafer treatment module arrangement interconnected to and operated by a central wafer handling robot to provide a unified system, the wafer treatment module including a loading port of a pre-aligner module for receiving a wafer to be treated, and a binder module for applying a fluxless fluid binder to a top surface of the wafer, the fluxless fluid binder configured to be completely evaporated from the top surface of the wafer at an elevated temperature, the binder module further including one or more nozzles configured to spray and evenly distribute the fluxless fluid binder across the top surface of the wafer. a binder module further including an air knife configured to direct a curtain of compressed air over the top surface of the wafer after the fluxless fluid binder has been sprayed and evenly distributed over the top surface of the wafer, the curtain of compressed air from the air knife to spread the fluxless binder applied over the top surface of the wafer leaving a uniform thin film of fluxless fluid binder over the top surface of the wafer; a solder ball mount module for attaching a number of solder balls onto the wafer; an inspection module including a review analysis and an insertion and extraction configuration for any incorrectly applied solder balls deposited on the wafer; and a reflow module for heating and fixing the solder balls onto a configuration of pads on the wafer, a binder module arranged to hold each wafer by a support pin vacuum arrangement during binder spray deposition and binder clean-up operations; a wafer pre-alignment operation at the load port and a transfer operation to a vacuum cup pin support in the solder wall mount module for optical alignment verification by multiple cameras; a solder ball dispensing stencil and a solder ball dispensing reservoir on the stencil for controlled release of solder balls onto the wafer below; means for collecting inadequate solder balls and excess binder; and a three station reflow module for final transfer to the load port for heat treatment of the loaded wafer or collection of the finished wafer.

2. 2. The wafer assembly configuration of claim 1, wherein the fluid binder is applied to the wafer at room temperature or at an elevated temperature, the one or more nozzles include a nozzle arrangement supported on a gantry movably positioned directly above a wafer supported therebelow, and excess binder is collected and utilized for additional wafers.

3. 3. The wafer assembly configuration of claim 2, wherein a number of solder balls are positioned as an array on the spaced apart pattern of solder ball engagement locations on the wafer after the solder balls are filtered through a vertical array of perforated solder ball alignment plates movably positioned above the wafer.

4. 4. The wafer assembly configuration of claim 3, wherein an air knife is actuated laterally relative to the array of solder balls on the top surface of the wafer such that any extraneous solder balls are pushed away from the surface of the wafer.

5. 5. The wafer assembly configuration of claim 4, wherein any extraneous solder balls are transferred to a unidirectional channel for collection and subsequent reuse on additional wafers.

6. 1. A wafer assembly arrangement for applying solder balls onto a wafer substrate for subsequent use in the electronics industry, the wafer assembly arrangement including an arrangement of individual wafer processing modules interconnected to and operated by a central wafer handling robot for moving wafers from module to module, the modules including a pre-aligner module for receiving a wafer to be processed, a binder module for applying a fluid binder to an upper surface of the wafer, a solder ball mount module for applying a number of solder balls onto the wafer, a reflow module for heating and bonding the solder balls onto an arrangement of pads on the wafer, and an inspection module for reviewing and analyzing the solder balls deposited on the wafer. a wafer assembly configuration, the processing of which includes a load port module for receiving the wafers to be processed, the binder module for holding each wafer by support pin vacuum means during binder spray deposition and binder clean-up operations, pre-alignment and transfer of the wafer at the load port to a vacuum cup pin support arrangement of the solder ball mount module for optical alignment review by multiple cameras, including a solder ball dispensing stencil, a solder ball dispensing reservoir directly above the stencil for controlling the release of solder balls onto the wafer below the stencil, and a means for collecting inadequate solder balls and excess binder, a three station reflow module for thermal treatment of the loaded wafer, and final transfer to the load port for finished wafer collection.

7. 7. The wafer assembly arrangement of claim 6, wherein the fluid binder is applied to the wafer by a nozzle arrangement supported on a main computer controlled gantry movably positioned directly above the wafer supported therebelow.

8. 8. The wafer assembly configuration of claim 7, wherein a number of solder balls are positioned as an array on the spaced apart pattern of solder ball engagement locations on the wafer after the solder balls fall through a vertical array of perforated solder ball alignment plates that are vibratably positioned above the wafer.

9. 9. The wafer assembly configuration of claim 8, wherein an air knife supported on the main gantry is actuated laterally relative to the array of solder balls on the top surface of the wafer such that any extraneous solder balls are pushed away from the surface of the wafer.

10. 10. The wafer assembly configuration of claim 9, wherein any extraneous solder balls are transferred past the one-way valve into a one-way channel for collection and subsequent reuse on additional wafers.

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