Next generation warpage measurement system

Systems, apparatuses and methods for determining a surface profile of a substrate are provided. In one embodiment, a method includes projecting a signal having a vertical component/profile across the surface of the substrate from a plurality of locations along a first side of the substrate, capturing the projected signals at each of a plurality of respective locations across the surface of the substrate and determining a surface profile for the substrate using the captured signals. The process can be automated using a controller having predetermined projection and capture positions along respective sides of the substrate, where a surface profile of the substrate can be automatically determined by the controller using the captured signals.

FIELD

Embodiments of the present disclosure generally relate to systems, apparatuses and methods for processing a substrate and, particularly, to systems, apparatuses and methods for determining a surface profile of a substrate.

BACKGROUND

Warped substrates are a problem which prevent the substrates from being chucked fully on a process chamber pedestal. Such warpage leads to a delay in or ceasing of the substrate processing.

For example, epoxy mold compounds are used to encapsulate dies in substrate packaging. These compounds bow and warp after thermal processes due to inhomogeneous heating and cooling, causing non-uniform expansion/contraction rates in current process equipment. Conventional thermal processes utilize directional heat transfer via radiative, convective or conductive thermal processes. The directionality results in anisotropic expansion and contraction rates. When operated near the thermoplastic regime, non-uniform cooling and, subsequently, contraction rates give rise to a warped substrate. Such warp and bow effects are frequently observed and imply that the substrate is being processed close to the thermoplastic regime of the substrate, giving rise to substrate warpage beyond acceptable levels.

Being able to detect and measure the warpage before, during or after any process would result in benefits to production throughput and yield.

SUMMARY

Embodiments of substrate measurement system, apparatus and method for determining a surface profile for a substrate to determine, for example, substrate warpage are provided herein. In various embodiments in accordance with the present principles, a method for determining a surface profile for a substrate includes projecting a signal having a vertical component/profile across the surface of the substrate from a plurality of locations along an edge of the substrate, capturing the projected signals at each of a plurality of respective locations across the surface of the substrate, and determining a surface profile for the substrate using the captured signals.

In another embodiment in accordance with the present principles, an apparatus for determining a surface profile for a substrate includes a first sensor pair including a first transmitter for projecting a signal having a vertical component/profile across a surface of the substrate from a plurality of locations along an edge of the substrate and a first receiver for capturing the projected signals from the first transmitter at each of a plurality of respective locations across the surface of the substrate. The apparatus further includes a first track assembly for moving the first sensor pair across at least a portion of the surface of the substrate, a first encoder for determining positional information associated with the first track assembly and a substrate support for holding the substrate. In various embodiments the first receiver communicates information associated with the captured signals from the first transmitter to a controller and the first encoder communicates the determined positional information of the first track assembly to the controller to be used by the controller to determine a surface profile for the substrate using the information associated with the captured signals and the positional information.

In some embodiments in accordance with the present principles, the above described apparatus further includes a second sensor pair including a second transmitter for projecting a signal having a vertical component/profile across a surface of the substrate perpendicular to the signal projected from the first transmitter from a plurality of locations along an edge of the substrate and a second receiver for capturing the projected signals from the second transmitter at each of a plurality of respective locations across the surface of the substrate. The apparatus can further include a second track assembly for moving the second sensor pair across at least a portion of the surface of the substrate, and a second encoder for determining positional information associated with the second track assembly. In such an embodiment, the second receiver communicates information associated with the captured signals from the second transmitter to the controller and the second encoder communicates the determined positional information of the second track assembly to the controller to be used by the controller to determine a surface profile for the substrate using the information associated with the captured signals and the positional information.

DETAILED DESCRIPTION

Systems, apparatuses and methods for determining a surface profile for a substrate to determine, for example, substrate warpage are provided herein. The inventive systems, apparatuses and methods advantageously facilitate the detection and measurement of a warped substrate. Although embodiments of the present principles will be described with respect to specific sensors having specific configurations, other types of sensors and sensor configurations can be used without departing from the scope of the present principles. In addition, although in the embodiments presented herein a sensor transmitting unit and receiving unit are depicted as having specific locations on an apparatus, the locations of the transmitting unit and receiving unit can be interchanged.

FIG. 1depicts a high level block diagram of a system100for determining a surface profile for a substrate in accordance with an embodiment of the present principles. The system100ofFIG. 1illustratively comprises a substrate measurement apparatus102and a controller104. In one embodiment of the present principles, a substrate to be measured is placed in the substrate measurement apparatus102and measurements taken by at least one sensor assembly (seeFIG. 2) of the substrate measurement apparatus102are communicated to the controller104for processing.

FIG. 2depicts a high level block diagram of a substrate measurement apparatus102for determining a surface profile for a substrate suitable for use in the system100ofFIG. 1in accordance with embodiments of the present principles. The substrate measurement apparatus102ofFIG. 2illustratively comprises a base110, a track assembly112, a sensor support assembly114, a sensor assembly (e.g., sensor pair) including a transmitter unit116and a receiver unit118, a substrate support assembly120including a substrate support base122and a substrate support124, and an encoder140. The substrate measurement apparatus102ofFIG. 2further depicts an optional guide130, which will be described in further detail below.

In the embodiment of the substrate measurement apparatus102ofFIG. 2, the transmitter unit116is mounted on one end of the sensor support assembly114and the receiver unit118is mounted on the other end of the sensor support assembly114. The sensor support assembly114is configured such that the transmitter unit116, when mounted on the sensor support assembly114, can be located on one side of the substrate support124and as such a substrate to be tested, and the receiver unit118, when mounted on the sensor support assembly114, can be located on the other side of the substrate support124and a substrate to be tested. In some embodiments, the receiver unit118is positioned directly across from the transmitter unit116on an opposite side of the substrate support124and a substrate to be tested.

The mounting of the transmitter unit116and the receiver unit118onto the sensor support assembly114and the positioning of the sensor support assembly114in the substrate measurement apparatus102are such that at least a portion of a signal communicated from the transmitter unit116toward the receiver unit118comes into contact with a surface of a substrate to be tested. In addition, the transmitter unit116and the receiver unit118are positioned on the sensor support assembly114such that a signal communicated from the transmitter unit116is directed to the receiver unit118to be captured by the receiver unit118.

Although in the embodiment ofFIG. 2, the sensor support assembly114comprises a “U”-shaped assembly, in other embodiments in accordance with the present principles, the sensor support assembly114can comprise substantially any shape that enables the transmitter unit116, when mounted on the sensor support assembly114, to be located on one side of a substrate to be tested and the receiver unit118, when mounted on the sensor support assembly114, to be located on the other side of a substrate to be tested, such that when the sensor support assembly114and mounted transmitter unit116and receiver unit118are moved across the substrate support124and a substrate to be tested, the sensor support assembly114and mounted transmitter unit116and receiver unit118do not come into contact with the substrate support124and a substrate to be tested and do not interfere with the testing of the substrate as described herein.

In the embodiment ofFIG. 2, the sensor support assembly114is mounted on the track assembly112such that the sensor support assembly114, having the sensor assembly mounted thereon, can be translated across at least a portion of the substrate support124and a substrate to be tested. As depicted in the embodiment ofFIG. 2, the track assembly112enables the movement of the sensor support assembly114, and mounted transmitter unit116and receiver unit118, across at least a portion of if not the entire substrate support124, which is mounted on the substrate support base122.

In the embodiment ofFIG. 2, the encoder140is mounted on the track assembly112. The encoder140can be used to determine positional information of the track assembly112as will be described in greater detail below.

Although in the embodiment ofFIG. 2, the track assembly112is depicted as being located on a right side of the substrate measurement apparatus102, in other embodiments in accordance with the present principles, the track assembly112can be located in substantially any position on the base110of the substrate measurement apparatus102that enables the track assembly112to move/translate the sensor support assembly114, having the sensor assembly mounted thereon, across at least a portion of a substrate to be tested without interfering with the measurements to be taken. In addition, although in the embodiment ofFIG. 2, the substrate support124and the substrate support base122are depicted as separate components, in other embodiments in accordance with the present principles, a substrate support and a substrate support base can comprise a single unit.

In the embodiment of the substrate measurement apparatus102ofFIG. 2, the track assembly112, the substrate support base122and the optional guide130are illustratively mounted to the base110. In the embodiment ofFIG. 2, the guide130is implemented to assist in moving the sensor support assembly114, having the sensor assembly mounted thereon, across the substrate support124. The guide130can be used to maintain a position of the sensor support assembly114, and as such the sensor assembly, relative to the substrate support124and, as such, a substrate to be tested as the sensor support assembly114is being moved across the substrate support124. For example, in one embodiment, the guide130can be used to assist in maintaining a level condition between the sensor support assembly114and, as such, the sensor assembly, and the substrate support124.

In some embodiments in accordance with the present principles, the track assembly112can comprise a linear actuator, the encoder140can comprise a linear encoder and the sensor assembly can comprise a laser micrometer. In alternate embodiments the track assembly112can comprise a Robo Cylinder® and the sensor assembly can comprise a sensor capable of projecting light or sound having at least a vertical component/profile and receiving at least a portion of the projected light or sound such that a determination can be made as to a surface profile of a substrate to be tested based on, for example, a portion of the light or sound received by a receiver and/or blocked (not received by the receiver) by the surface of a substrate under test.

FIG. 3depicts a high level block diagram of a controller104suitable for use in the system100ofFIG. 1in accordance with an embodiment of the present principles. The controller104ofFIG. 3illustratively comprises a processor310as well as a memory320for storing control programs, buffer pools, human-machine interface (HMI) programs, graphical user interface (GUI) programs and the like. The processor310cooperates with support circuitry330such as power supplies, clock circuits, cache memory and the like as well as circuits that assist in executing the software routines/programs stored in the memory320. As such, some of the process steps discussed herein as software processes may be implemented within hardware, for example, as circuitry that cooperates with the processor310to perform various steps. The controller104also contains input-output circuitry340that forms an interface between the various functional elements communicating with the controller104. As depicted in the embodiment ofFIG. 3, the controller104can further include a display350.

Although the controller104ofFIG. 3is depicted as a general purpose computer, the controller104is programmed to perform various specialized control functions in accordance with the present principles and embodiments can be implemented in hardware, for example, as an application specified integrated circuit (ASIC). As such, the process steps described herein are intended to be broadly interpreted as being equivalently performed by software, hardware, or a combination thereof.

In one operational embodiment, a substrate is mounted on the substrate support124. The track assembly112is then used to move the sensor support assembly114, having the sensor assembly thereon, across the surface of the substrate. During the movement, the transmitter unit116projects a signal, for example a laser beam having a vertical component/profile (e.g., a column of laser light), across the surface of the substrate to the receiver unit118. For example, the track assembly112positions the transmitter unit116at various positions along one side of the substrate under test such that the transmitter unit116is able to project a signal (e.g., a vertical column of light) from various locations along the edge of one side of the substrate, across the substrate surface, to various respective locations on the other side of the substrate.

The receiver unit118captures the projected signal (e.g. vertical column of light) and detects any disturbances or interruptions in the signal from the transmitter unit116. For example, in an embodiment in which the sensor assembly comprises a digital micrometer, the transmitter unit116directs a laser beam having a vertical component/profile across the surface of the substrate to the receiver unit118. If the substrate is warped, the elevated portions of the warped substrate will block portions of the laser beam captured by the receiver unit118. Information regarding the remaining laser signal captured by the receiver unit118or the laser signal blocked by the surface of the substrate under test can be used to generate a profile of a surface of the substrate.

For example, in various embodiments the dimensions of the signal projected from the transmitter unit116are known. As the signal from the transmitter unit116moves across the surface of a substrate, raised portions on the surface of the substrate block portions of the signal as is translates across the surface of the substrate. As such, the respective signals captured by the receiver unit118, as the receiver unit118moves across the surface of the substrate, will be missing some portion of the signal. Information regarding, for example, a height of the portion of the missing signal can be used to determine a height of the rise in the surface of the substrate for the location on the surface of the substrate over which the signal traveled before being captured by the receiver unit118.

In one embodiment in accordance with the present principles, the sensor assembly has an internal alignment system that produces a small optical signal when the transmitter unit116and receiver unit118are properly aligned. In various embodiments, the transmitter unit116can be aligned such that a bottom of the signal (e.g., vertical column of light) from the transmitter unit116just touches a top surface of the substrate support124. In some other embodiments, the transmitter unit116can be aligned such that a bottom of the signal from the transmitter unit116just touches a lowest point on the top surface of a substrate to be tested.

In one operational embodiment in accordance with the present principles, the sensor assembly (e.g., digital micrometer) is moved over a distance equal to the entire surface of a substrate on the substrate support124and measurements are collected by the sensor assembly, based on a sampling rate, during the length of the travel. The collected measurements are used to generate a profile of the surface of the substrate as seen from the sides (as described above), resulting in a representation of the shape of the substrate surface at least at portions of the substrate at which sensor measurements were taken. During such measurements, the encoder140provides positional information of the sensor support assembly114and as such, the sensor assembly, to, for example, the controller104. Such positional information can include a position of the sensor assembly with respect to a location on the surface of a substrate under test for at least locations on the surface of the substrate at which measurements were taken. The measurement information for the receiver unit118and the positional information from the encoder can be associated with a time and location relative to the substrate surface during which the sensor assembly is triggered to take measurements. Such measurement information and positional information can be used by the controller104to determine a surface profile for a substrate under test. The controller104can provide data management, for example, the visual presentation of data, for detecting trends, patterns, signatures and the like. The data can then be collected, analyzed and used to, for example, devise corrective or preventive measures for warped substrates.

In various embodiments in accordance with the present principles, the controller104is implemented to control the movement of the sensor support assembly114via the track assembly112(e.g., linear actuator) and to trigger measurements by the sensor assembly (e.g., laser micrometer). For example, in one operational embodiment, the controller104communicates a signal to the track assembly112to cause the track assembly112to move at predetermined increments. The controller104can then communicate a signal to the sensor assembly to project a signal across the surface of the substrate using the transmitter unit116and to capture the projected signal using the receiver unit118.

For example, in one embodiment, the controller104communicates a signal to the track assembly112to cause the track assembly to move in increments of 10 mm, although other increments can be used. In various embodiments, the encoder140on the track assembly112communicates a feedback signal to the controller104to inform the controller104of the position of the track assembly112. When the track assembly112reaches an intended position, the controller104communicates a signal to the sensor assembly to cause the sensor assembly to capture a measurement at the intended position. The sensor assembly communicates a signal representative of the measurement to the controller104. The controller104can store the received signal to be used to determine a profile of the surface of the substrate and/or present a representation of the signal associated with the measurement on the display350.

FIG. 4depicts a graphical representation of plotted measurements of the sensor assembly of a substrate measurement apparatus in accordance with an embodiment of the present principles on a flat substrate.FIG. 5depicts a graphical representation of plotted measurements of the sensor assembly of a substrate measurement apparatus in accordance with an embodiment of the present principles on a warped substrate. As depicted inFIG. 4, the compiled measurement results indicate a flat profile for the substrate under test. In the embodiment ofFIG. 4, sensor assembly measurements were taken, as described above, at increments of 10 mm across a substrate having a diameter of 300 mm. The plotted sensor measurements result in a baseline profile having a height of 770 μm across the entire measured surface of the substrate ofFIG. 4.

The same measurement apparatus in accordance with the present principles was used to measure a warped substrate. In the embodiment ofFIG. 5, sensor measurements were again taken at increments of 10 mm across a warped substrate having a diameter of 300 mm. As depicted inFIG. 5, the plotted sensor measurements depict an obvious decline in the height of the warped substrate. InFIG. 5, an initial sensor measurement indicated a height for the substrate of approximately 1050 μm and a final sensor measurement indicated a height for the substrate of approximately 770 μm, with sensor measurements in between the first and last measurement points indicating a steady decline in the height of the substrate between those two points.

The plotted measurements ofFIG. 4andFIG. 5can be presented on a display350of, for example, the controller104using a HMI or graphical user interface to be presented to a user.

Using the data collected by the sensor assembly in accordance with the present principles, a determination can be made regarding whether the surface of a substrate is warped or flat and the extent to which the surface of a substrate is warped or flat. Such information can be used to compare the measurements of a measured substrate with tolerances for substrate surface flatness to determine, for example, if a substrate is acceptable for processing or not. If determined, based on the tolerances, that a substrate is not suitable for processing, the substrate can be sent to undergo corrective measures or can be eliminated from a processing routine.

FIG. 6depicts a flow diagram of a method600for determining a surface profile of a substrate, for example, to determine warpage in accordance with an embodiment of the present principles. The method600begins at602during which a signal having a vertical component/profile is projected across a top surface of the substrate from a plurality of locations along a first side of the substrate. For example and as described above, a transmitter unit can project a signal having a vertical component/profile, such as a vertical laser column or any other vertical component of light or sound, from different locations along a first side of the substrate and across the surface of the substrate toward a receiver unit. The method can proceed to604.

At604, the projected signals are captured at each of a plurality of respective locations on a second side of the substrate located across the surface of the substrate. For example and as described above, a receiver unit aligned to receive the signals from the transmitter captures the signal after the signal translates across the surface of the substrate. The method can proceed to606.

At606, a surface profile for the substrate is determined using the captured signals. For example and as described above, the signals captured by the receiver unit at each respective location, includes a portion of the light column that was not blocked by any rise in the surface of the substrate. Such information is used, for example, by the controller to determine a surface profile of the substrate. That is, the encoder communicates positional information to the controller of a location of the sensor assembly with respect to the surface of the substrate and the receiver unit communicates signal information to the controller. Having such information, the controller is able to determine a representation of the surface of the substrate. The method600can then be exited.

In some embodiments in accordance with the present principles, the controller104includes a HMI or graphical user interface, which is presented on a display, such as display350, such that a user is able to input test parameters and view profile results on the included display. For example, in one embodiment a user is able to input, using an input device such as a keyboard or touch screen of the controller104, step increments or positional information as to where on a substrate under test a user would like sensor measurements taken. A user is also able to input information necessary to run a test as described above and have the controller automatically perform the test procedures. A user can also indicate that a test be run continuously and have the track assembly112run continuously as the sensor assembly takes continuous measurements. The signal results captured by the receiving unit are communicated to the controller104and the positional information from the encoder is communicated to the controller for use by the controller in determining a surface profile for the substrate under test. Such information can be used to determine if a surface of the substrate is warped and, if so, an amount of the warpage.

In various embodiments in accordance with the present principles, a controller104determines a surface profile of a substrate by recording received measurements with respect to received positional information to associate a height measurement of the surface of the substrate with where on the surface of the substrate the height measurement was taken. As described above, such information can be plotted on a graph for example as measurement height versus location on the surface of the substrate at which the measurement was taken, and presented on a display as a surface profile for a substrate under test. Such information can also be stored in a memory of the controller104.

In various embodiments in accordance with the present principles, the substrate measurement apparatus102can be incorporated into an existing process chamber. For example, in one embodiment, the track assembly112, the encoder140, the sensor support assembly114including the transmitter unit116and the receiver unit118, can be installed into an existing process chamber. As such, a substrate to be tested can be placed on a support pedestal of the process chamber and the sensor support assembly114including the transmitter unit116and receiver unit118, the track assembly112and encoder140can be implemented as described herein to determine a surface profile for a substrate in the existing process chamber to, for example, determine if the substrate is warped. In other embodiments, a substrate measurement apparatus102, or at least portions thereof, can be temporarily positioned, for example as a sub-assembly, in an existing process chamber to determine a surface profile for a substrate in the existing process chamber as described above.

In various embodiments in accordance with the present principles, a substrate measurement apparatus comprises a second track assembly, a second encoder, a second sensor support assembly and a second sensor assembly. For example,FIG. 7depicts a high level block diagram of the substrate measurement apparatus ofFIG. 2including a second track assembly712, a second encoder (not shown) mounted on the second track assembly712, a second sensor support assembly714and a second sensor assembly including a second transmitter unit716and a second receiver unit718. In the embodiment ofFIG. 7, the second track assembly712, second encoder (not shown), second sensor support assembly714and second sensor assembly including the second transmitter unit716and the second receiver unit718are implemented to project and capture a signal in a direction perpendicular to the projected and captured signal described with respect to the substrate measurement apparatus102ofFIG. 2. As such, in the embodiment ofFIG. 7, the substrate measurement apparatus is capable of taking measurements of a single point on the surface of the substrate, the single point being defined by where the signals from the first transmitter unit116and the second transmitter unit716cross on the surface of the substrate. In such embodiments, the first sensor support assembly114having the first sensor assembly mounted thereon and the second sensor support assembly714having the second sensor assembly mounted thereon can be moved independently and at different times or in other embodiments can be moved in unison.