Patent Description:
Current computing systems involve dense integrations of a range of different elements, including processors, application specific integrated circuit accelerators, memory devices, high speed input/output devices, network processing devices, and power delivery/power management devices. Issues arise while probing individual devices to determine if the devices are working properly. If the probing system cannot accommodate tilt displacements, only part of the device will be contacted. Many factors that contribute to tilting angle errors are pressure dependent and may be transient under loads.

Accordingly, those skilled in the art continue with research and development efforts in the field of tilt calibration to provide uniform probing of devices-under-test.

<CIT>, in accordance with its abstract, states: A water probe alignment System and method for aligning a probe to a chip wafer for testing a chip on the wafer are provided. At least two comers of the probe are adjustable in a same direction in relation to a primary comer of the probe. The alignment approach includes providing a grid of signal pins for corresponding contact pads of the chip under lest, determining for each signal pin whether an electrical contact is established to a corresponding contact pad of the chip under contact force, and adjusting a position of each of the at least two comers by a comer individual delta position value with respect to the direction depending on a result of the determining in order to establish an electrical contact between each of the pins and the corresponding contact pads of the chip under test.

HP-H05 <NUM><NUM> A, in accordance with its abstract, states: A probe card which is provided with a probe needle is attaches directly to a test Mac; a detection means which detects the inclination of the probe card with reference to a mounting stand is attaches to the mounting stand which supports an object under test; a correction means which corrects the inclination of the mounting stand on the basis of information from the detection means is installed. The correction means is composer of three support parts which support the mounting stand and whose length can be changed. By charging the length of each support part, the inclination of the mounting stand is corrected. Thereby, since the probe card can be attached directly to the test head, the connecting part such as a measuring cable or the like between the test head and the probe card can be eliminated, an increase in the impedance of the title apparatus can be eliminated and a high-frequency measurement can be performed accurately.

According to the present disclosure, a probing system, a method and a calibration kit as defined in the independent claims are provided. Further embodiments of the invention are defined in the dependent claims. Although the invention is only defined by the claims, the below embodiments, examples, and aspects are present for aiding in understanding the background and advantages of the invention.

A probing system is provided herein. The probing system includes a device-under-test, a probe device, and a die bonder. The device-under-test includes a plurality of test patterns on a first surface. The probe device includes a plurality of tilt angle sensors. The plurality of tilt angle sensors include a plurality of spikes that protrude from a second surface of the probe device. The die bonder has a spherical positioner that is adjustable in a plurality of rotational axes. The die bonder is operational to mount the device-under-test with the first surface facing outward, mount the probe device with the second surface of the probe device facing the first surface of the device-under-test, compress the probe device and the device-under-test together with a first force that causes a subset of the plurality of spikes to contact the plurality of test patterns, measure a number of electrical connections formed between the plurality of tilt angle sensors and the plurality of test patterns, determine a first offset angle and a second offset angle between the first surface of the device-under-test and the second surface of the probe device based on the number of electrical connections, separate the probe device from the device-under-test, and adjust the spherical positioner in one or more of the plurality of rotational axes in response to the first offset angle and the second offset angle to change a parallelism between the first surface of the device-under-test and the second surface of the probe device.

In one or more embodiments of the probing system, the die bonder is further operational to compress the probe device and the device-under-test together with a second force after the spherical positioner is adjusted. The second force is greater than the first force.

In one or more embodiments, the probing system includes a meter operational to measure a plurality of total tilt conductances through the plurality of tilt angle sensors and the plurality of test patterns. Each of the plurality of tilt angle sensors includes two sets of the plurality of spikes. Each of the plurality of test patterns includes a plurality of pattern traces. Each of the plurality of pattern traces contributes a respective tilt conductance between the two sets while electrically connected to at least one spike of the plurality of spikes in each of the two sets.

In one or more embodiments of the probing system, the die bonder includes a processor operational to receive the plurality of total tilt conductances from the meter, calculate the first offset angle and the second offset angle based on the plurality of total tilt conductances, and control the adjustment of the spherical positioner in response to the first offset angle and the second offset angle.

In one or more embodiments of the probing system, the first offset angle is determined with a first group of the plurality of tilt angle sensors that are oriented in a first direction. The second offset angle is determined with a second group of the plurality of tilt angle sensors that are oriented in a second direction. The first direction is orthogonal to the second direction.

In one or more embodiments, the probing system includes a plurality of test pads disposed on the first surface of the device-under-test, and a plurality of probe tips that protrude from the second surface of the probe device. At least two probe tips of the plurality of probe tips contact each respective test pad of the plurality of test pads. The probing system further includes a meter operational to measure a touchdown conductance through each of the at least two probe tips and the respective test pad.

In one or more embodiments, the probing system includes a plurality of resilient pillars disposed between the plurality of spikes and the second surface of the probe device to account for height variations among the plurality of test patterns.

In one or more embodiments, the probing system includes a plurality of resistor networks disposed on the first surface of the device-under-test, a plurality of position sensors that protrude from the second surface of the probe device, and a meter operational to measure a plurality of position resistances through the plurality of position sensors and the plurality of resistor networks. The plurality of position resistances determines a first horizontal alignment and a second horizontal alignment between the device-under-test and the probe device. The first horizontal alignment and the second horizontal alignment are in orthogonal directions.

In one or more embodiments of the probing system, a first group of the plurality of test patterns are disposed around a periphery of the device-under-test. A second group of the plurality of test patterns are disposed in a central area of the device-under-test.

A method to aid in a tilt calibration for probing is provided herein. The method includes mounting a device-under-test in a die bonder with a first surface of the device-under-test facing outward. The device-under-test has a plurality of test patterns on the first surface. The die bonder has a spherical positioner that is adjustable in a plurality of rotational axes. The method further includes mounting a probe device in the die bonder with a second surface of the probe device facing the first surface of the device-under-test. The probe device has a plurality of tilt angle sensors. The plurality of tilt angle sensors have a plurality of spikes that protrude from the second surface. The method includes compressing the probe device and the device-under-test together with a first force that causes a subset of the plurality of spikes to contact the plurality of test patterns, measuring a number of electrical connections formed between the plurality of tilt angle sensors and the plurality of test patterns, determining a first offset angle and a second offset angle between the first surface of the device-under-test and the second surface of the probe device based on the number of electrical connections, separating the probe device from the device-under-test, and adjusting the spherical positioner in one or more of the plurality of rotational axes in response to the first offset angle and the second offset angle to change a parallelism between the first surface of the device-under-test and the second surface of the probe device.

In one or more embodiments, the method further includes compressing the probe device and the device-under-test together with a second force after the spherical positioner is adjusted, wherein the second force is greater than the first force.

In one or more embodiments of the method, the measuring of the number of electrical connections includes measuring a plurality of total tilt conductances through the plurality of tilt angle sensors and the plurality of test patterns. Each of the plurality of tilt angle sensors includes two sets of the plurality of spikes. Each of the plurality of test patterns includes a plurality of pattern traces. Each of the plurality of pattern traces contributes a respective tilt conductance between the two sets while electrically connected to at least one spike of the plurality of spikes in each of the two sets.

In one or more embodiments, the method further includes receiving at a processor the plurality of total tilt conductances, calculating the first offset angle and the second offset angle based on the plurality of total tilt conductances, and controlling the adjustment of the spherical positioner with the processor in response to the first offset angle and the second offset angle.

In one or more embodiments of the method, the determining of the first offset angle and the second offset angle includes determining the first offset angle with a first group of the plurality of tilt angle sensors that are oriented in a first direction, and determining the second offset angle with a second group of the plurality of tilt angle sensors that are oriented in a second direction. The first direction is orthogonal to the second direction.

In one or more embodiments, the method further includes measuring a touchdown conductance through each of at least two probe tips of a plurality of probe tips and a respective test pad of a plurality of test pads. The plurality of test pads are disposed on the first surface of the device-under-test. The plurality of probe tips extend from the second surface of the probe device. At least two probe tips of the plurality of probe tips contact each respective test pad of the plurality of test pads.

In one or more embodiments, the method further includes measuring a plurality of position resistances through a plurality of position sensors and a plurality of resistor networks, and determining a first horizontal alignment and a second horizontal alignment between the device-under-test and the probe device based on the plurality of position resistances. The plurality of resistor networks are disposed on the device-under-test. The plurality of position sensors are disposed on the probe device. The first horizontal alignment and the second horizontal alignment are in orthogonal directions.

A calibration kit is provided herein. The calibration kit includes a probe device, a device-under-test, a meter, and a processor. The probe device includes a plurality of tilt angle sensors. The plurality of tilt angle sensors have a plurality of spikes that protrude from a second surface of the probe device. Each of the plurality of tilt angle sensors includes two sets of the plurality of spikes. The device-under-test includes a plurality of test patterns disposable on a first surface. Each of the plurality of test patterns includes a plurality of pattern traces. Each of the plurality of pattern traces contributes a respective tilt conductance between the two sets while electrically connected to at least one spike of the plurality of spikes in each of the two sets. The meter is operational to measure a number of electrical connections formed between the plurality of tilt angle sensors and the plurality of test patterns while compressed together. The processor is operational to determine a first offset angle and a second offset angle between the first surface of the device-under-test and the second surface of the probe device based on the number of electrical connections.

In one or more embodiments of the calibration kit, the first offset angle and the second offset angle are correctable to less than <NUM> microradians.

In one or more embodiments of the calibration kit, a pitch of the plurality of spikes is less than <NUM> micrometers.

In one or more embodiments of the calibration kit, the plurality of pattern traces is formed from gold, aluminum, indium, copper, platinum, palladium, or an alloy thereof. The plurality of spikes is formed from one of (i) a single metal, (ii) an alloy and (iii) a layered combination selected from beryllium, gold, titanium, palladium, vanadium, copper, manganese, nickel, cobalt, iron, rhodium, chromium, molybdenum, ruthenium, platinum, tantalum, tungsten, rhenium, iridium, aluminum oxide, and silicon carbide.

The above features and advantages, and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings.

Embodiments of the present disclosure generally include a system, method and/or kit that addresses tilt calibration of a probing device used in testing a device-under-test. The designs disclosed herein provide in-situ tilt angle sensors and control methods that provide local touchdown contact and global tilt angle measurements under load conditions to ensure high yield probing of fine-pitch area arrays. The tilt-angle sensors have a compact set of integrated sensors for fine-pitch area array probers that provides local contact sensing and global tilt angle measurements during low-force touchdowns, and feedback signals utilized by a prober platform (precision hardware) to correct non-parallel orientations. The tilt angle sensors are arranged as a set of distributed touchdown sensing units spread across the probe device, each with a set of redundant sensors (e.g., bridging contactor links with spikes on the probe device side that are short traces on the device-under-test). The tilt sensors may be positioned around a perimeter and in a central area of a probe device and the device-under-test. The arrangement and numbers of tilt angle sensors determines an accuracy of the tilt angle measurement. The tilt angle sensors provide information on a physical contact state of a particular location during touchdown of the probe device on the device-under-test. The information taken collectively, provides a measurement of the global tilt angle. The global tilt angles may be corrected by the prober platform using the information provided by the tilt angles sensors.

Referring to <FIG>, a schematic diagram of an example implementation of a probing system <NUM> is shown in accordance with one or more exemplary embodiments. The probing system <NUM> generally includes a die bonder <NUM> and a computer <NUM>. The die bonder <NUM> includes a spherical positioner <NUM>, a top chuck <NUM>, a bottom chuck <NUM>, and a load cell <NUM>. The computer <NUM> includes one or more processors <NUM> (one shown), one or more memory devices <NUM> (one shown), and one or more meters <NUM> (one shown).

The die bonder <NUM> implements a precision die bonder. In various embodiments, the die bonder <NUM> implements a substrate-to-substrate thermocompression press. For example, the die bonder <NUM> may be an FC300 precision die bonder available from Setna, LLC, Chester, New Hampshire. The die bonder <NUM> is operational to align and press the probe device <NUM> onto the device-under-test <NUM>. The alignment may be provided by movement of the top chuck <NUM> relative to the bottom chuck <NUM> in multiple directions (e.g., a first direction 134c (e.g., X) and a second direction 134b (e.g., Y)). The multi-directional movement is provided, in part, by the spherical positioner <NUM>. The top chuck <NUM> is moveable relative to the bottom chuck <NUM> in a vertical direction 134a (e.g., -Z).

Movement of the top chuck <NUM> downward along the vertical direction 134a presses a probe device <NUM> being held by the top chuck <NUM> with one of a first force 136a or a second force 136b against a device-under-test <NUM> being held by the bottom chuck <NUM>. The first force 136a of the second force 136b compresses spikes formed on the probe device <NUM> into multiple test patterns on the device-under-test <NUM>. In some embodiments, the device-under-test <NUM> may be held by the top chuck <NUM> and the probe device <NUM> may be held by the bottom chuck <NUM>. The load cell <NUM> measures the first force 136a and the second force 136b being applied between the device-under-test <NUM> and the probe device <NUM>.

The spherical positioner <NUM> implements a multi-dimensional joint. The spherical positioner <NUM> may tilt (or rotate) <NUM> the top chuck <NUM> relative to the bottom chuck <NUM>. The tilt <NUM> may include movement in a pitch direction (or axis) 130a and a roll direction (or axis) 130b to align (e.g., make parallel) the facing surfaces of the probe device <NUM> and the device-under-test <NUM>. The spherical positioner <NUM> also provides rotation of the top chuck <NUM> relative to the bottom chuck <NUM> in a yaw direction (or axis) <NUM>. In some embodiments, the bottom chuck <NUM> may be rotatable relative to the top chuck <NUM> in the yaw direction <NUM>.

The top chuck <NUM> and the bottom chuck <NUM> each implement a vacuum chuck. The top chuck <NUM> and the bottom chuck <NUM> are operational to hold the probe device <NUM> and the device-under-test <NUM> during the probing process.

The load cell <NUM> implements a pressure sensor. The load cell <NUM> is operational to detect the forces 136a-136b applied by the probe device <NUM> onto the device-under-test <NUM> during use of the die bonder <NUM>.

The computer <NUM> is coupled to the probe device <NUM> and the load cell <NUM>. The computer <NUM> implements one or more data processing computers. In embodiments with multiple computers <NUM>, the individual computers <NUM> are coupled together to share data, memory space, and processing resources. The computer <NUM> may be operational to store the configuration data of the die bonder <NUM> and execute software used to analyze the information received from the probe device <NUM>, the load cell <NUM>, and the meter <NUM>.

The processor <NUM> implements one or more processors within the computer <NUM>. The processor <NUM> is in communication with the memory device <NUM> and the meter <NUM> to exchange commands and data. The processor <NUM> is operational to execute the software tools used to analyze the data generated by the probe device <NUM>, the load cell <NUM>, and the meter <NUM>.

The memory device <NUM> implements one or more non-transitory computer readable storage devices (e.g., random access memory, read-only memory, magnetic hard drives, solid-state drives, etc.). The memory device <NUM> stores software programs (or tools) that are executed by the processor <NUM>.

The meter <NUM> implements one or more conductance, resistance, voltage and/or current meters. The meter <NUM> is operational to detect and report changes in conductance/resistance in response to various spikes of the probe device <NUM> making electrical contact with the test patterns on the device-under-test <NUM>. The meter <NUM> is also operational to measure voltages and/or currents at test pads on the device-under-test <NUM> during probing operations.

The probing system <NUM> implements a technique for measuring a multi-dimensional tilt between the device-under-test <NUM> and the probe device <NUM>. Probing of fine-pitch area arrays (e.g., less than <NUM> micrometers (µm) pitch arrays) is sensitive to a degree of parallelism between the upward-facing first surface (or first side) of the device-under-test <NUM> is with the downward-facing second surface (or second side) of the probe device <NUM>. The probing system <NUM> provides high-resolution tilt measurements (e.g., less than ±<NUM> microradians) over large area substrates, including wafers, tiles, and/or die level substrates. Arrays of fine-pitch metal knife-edge-like structures (e.g., spikes) are arranged as multiple tilt angle sensors on the second surface of the probe device <NUM>. Matching arrays conductive traces are arranged as multiple test patterns on the first surface of the device-under-test <NUM>. The spikes of the tilt angle sensors are used to electrically contact the test patterns as the probe device <NUM> and the device-under-test <NUM> are brought together. The spikes may be fabricated as conically symmetric tips in a photolithographic process that enables spike arrays to be formed on silicon or other substrates over large areas with low variation in tip heights. The conductive traces may be fabricated as metal stipes. The test patterns and the tilt angle sensors are be positioned around a periphery of the probe device <NUM> and the device-under-test <NUM>. Some of the test patterns and the tilt angle sensors may also be positioned within an interior region of the probe device <NUM> and the device-under-test <NUM>. Knowledge of proper tilt alignment between the device-under-test <NUM> and the probe device <NUM> provides confidence while probing high density interfaces that are subsequently used to fabricate two-and-a-half dimensional and three-dimensional integrated microelectronic systems. Redistribution layers may route the individual array spike probes to an edge of the probe device <NUM> for subsequent readout to the computer <NUM>.

Referring to <FIG>, a schematic plan diagram of example implementations of various substrates are shown in accordance with one or more exemplary embodiments. The substrate (e.g., the device-under-test <NUM> and/or the probe device <NUM>) may be formed of a semiconductor <NUM>. The semiconductor <NUM> generally includes silicon, germanium, gallium arsenide, aluminum gallium arsenide, silicon carbide, gallium nitride, indium phosphide and the like. The substrates may be in the form of a semiconductor die <NUM>, a semiconductor tile <NUM>, or a semiconductor wafer <NUM>.

Referring to <FIG>, a schematic diagram of an example arrangement of a calibration kit <NUM> is shown in accordance with one or more exemplary embodiments. The calibration kit <NUM> generally includes the device-under-test <NUM> and the probe device <NUM>. The device-under-test <NUM> is generally positioned below the probe device <NUM> in the die bonder <NUM> (<FIG>). The device-under-test <NUM> has a first surface <NUM> facing a second surface <NUM> of the probe device <NUM>. The device-under-test <NUM> includes a third surface <NUM> opposite the first surface <NUM>. Likewise, the probe device <NUM> includes a fourth surface <NUM> opposite the second surface <NUM>.

Multiple test patterns <NUM> and multiple test pads <NUM> are fabricated on the first surface <NUM> of the device-under-test <NUM>. The test patterns <NUM> may be fabricated as one or more layers of a variety of test pattern materials <NUM>. The test pattern materials 148a-<NUM> may include, but are not limited to, gold 148a, aluminum 148b, indium 148c, copper 148d, platinum 148e, palladium 148f, and alloys thereof <NUM>. The test pads <NUM> may be fabricated of materials similar to the test pattern materials <NUM>.

Multiple tilt angle sensors <NUM> and multiple contact probes <NUM> are fabricated on the second surface <NUM> of the probe device <NUM>. The tilt angle sensors <NUM> include multiple support pads <NUM> and multiple spikes <NUM>. The support pads <NUM> are fabricated on the second surface <NUM> of the probe device <NUM>. One or more spikes <NUM> are fabricated on the support pads <NUM> of the tilt angle sensors <NUM>. The spikes <NUM> are fabricated as one or more layers of a spike material <NUM>. The spike materials 170a-170u may include, but are not limited to, a single metal, single, an alloy, or a layered combination. The materials are generally selected from beryllium 170a, gold 170b, titanium 170c, palladium 170d, vanadium 170e, copper 170f, manganese <NUM>, nickel <NUM>, cobalt 170i, iron 170j, rhodium <NUM>, chromium <NUM>, molybdenum <NUM>, ruthenium 170n, platinum 170o, tantalum 170p, tungsten 170q, rhenium 170r, iridium <NUM>, aluminum oxide 170t and silicon carbide 170u.

The contact probes <NUM> include multiple support pads <NUM> and multiple probe tips <NUM>. The support pads <NUM> are fabricated on the second surface <NUM> of the probe device <NUM>. One or more probe tips <NUM> are fabricated on each support pad <NUM> of the contact probes <NUM>. In various embodiments, the probe tips <NUM> may be created same as the spikes <NUM> to match a height of the spikes <NUM> used in the tilt angle sensors <NUM>. Other tip designs may be implemented in the contact probes <NUM> to meet a design criteria of a particular application.

The first force 136a that presses the probe device <NUM> against the device-under-test <NUM> is a low force touch-down force (e.g., <NUM> to <NUM> micro-Newtons (µN)/spike) use during tilt angle measurements. The second force 136b is a standard probing force (e.g., approximately <NUM>µN/spike) used while electrically testing the device-under-test <NUM>.

Referring to <FIG>, a schematic plan diagram of an example device layout <NUM> is shown in accordance with one or more exemplary embodiments. The device layout <NUM> illustrates a device-under-test <NUM> and a probe device <NUM>. The device layout <NUM> generally defines multiple areas, including a periphery <NUM> and a central area <NUM>. A first group <NUM> of the tilt angle sensors <NUM> and a corresponding co-aligned group of the test patterns <NUM> are disposed in the periphery <NUM> of the device-under-test <NUM> and the probe device <NUM>. In various embodiments, a second group <NUM> of the tilt angle sensors <NUM> and a corresponding co-aligned group of the test patterns <NUM> are disposed in the central area <NUM> of the device-under-test <NUM> and the probe device <NUM>. A multiplexer <NUM> (or other suitable routing circuitry, including the redistribution layers) may be included on the probe device <NUM> to help connect the various tilt angle sensors <NUM> to the meter <NUM> (<FIG>).

During an initial touch-down of the probe device <NUM> onto the device-under-test <NUM>, some to every tilt angle sensors <NUM> make physical and electrical contact with the co-aligned test patterns <NUM> thereby forming closed circuits that can be sensed by the meter <NUM>. If a subset of the tilt angle sensor <NUM> do not contact the co-aligned test patterns <NUM>, the probe device <NUM> may be raised off the device-under-test <NUM>, the spherical positioner <NUM> adjusted to improve the planarization, and the probe device <NUM> is lowered onto the device-under-test <NUM> a second time.

Referring to <FIG>, a schematic plan diagram of an example implementation of an angle sensor layout <NUM> is shown in accordance with one or more exemplary embodiments. The angle sensor layout <NUM> illustrates the test pattern <NUM> and a tilt angle sensor <NUM>. The test pattern <NUM> generally includes multiple pattern traces <NUM> on the first surface <NUM> of the device-under-test <NUM>. In various embodiments, the tilt angle sensor <NUM> may have relatively lower alignment accuracy while still sensing the tilt angles of the probe device <NUM> relative to the device-under-test <NUM>. In some embodiments, the tilt angle sensor <NUM> has a similar pitch as the device-under-test <NUM> array, although the tolerance may be relaxed. The pattern traces <NUM> are formed of a conductive material. The tilt angle sensor <NUM> includes two sets of conductive traces <NUM> aligned orthogonal to and crossing the pattern traces <NUM>. Multiple spikes <NUM> are disposed on the conductive traces <NUM> and are aligned with the pattern traces <NUM>. While a given pattern trace <NUM> is in physical and electrical contact with at least two spikes <NUM>, one spike <NUM> in each of the two conductive traces <NUM>, a closed circuit is formed. The closed circuit has a tilt conductance <NUM>. In various embodiments, sensing one or more closed circuits, and thus establishing a non-zero tilt conductance <NUM>, may be used to by the processor <NUM> (<FIG>) to determine the tilt angles. In other embodiments, each pattern trace <NUM> may include a small resistance. A sum of the tilt conductances <NUM> formed through individual ones of the pattern traces <NUM> in contact with the conductive traces <NUM> through the spikes <NUM> establishes a total tilt conductance <NUM>. A number of contacts through the pattern traces <NUM> determines a value of the total tilt conductance <NUM>. The meter <NUM> (<FIG>) may measure the value of the total tilt conductance <NUM> between the conductive traces <NUM> and the pattern traces <NUM> through the spikes <NUM>. From the value of the total tilt conductance <NUM>, the processor <NUM> (<FIG>) may determine how many pattern traces <NUM> of each test pattern <NUM> are in contact with the corresponding tilt angle sensors <NUM>.

Referring to <FIG>, a schematic plan diagram of an example method <NUM> for fabrication of the spikes <NUM> is shown in accordance with one or more exemplary embodiments. The method <NUM> includes steps <NUM> to <NUM>, as illustrated. The sequence of steps is shown as a representative example. Other step orders may be implemented to meet the criteria of a particular application. The method (or process) <NUM> may be performed using standard semiconductor fabrication techniques. A shape and dimensions of the spikes <NUM> are controlled by a lithographic patterning used to define a base diameter of the spikes <NUM>. Deposited metal is used to fabricate the spikes <NUM>.

In the step <NUM>, the second surface <NUM> of the probe device <NUM> may be cleaned and prepared for a metal deposition. A metal for the pads <NUM> is deposited and patterned in the step <NUM>. A mask is deposited on the pads <NUM> in the step <NUM>. The mask may be a reverse image or bilayer resist process so that when images, re-entrant sidewalls result. In various embodiments, the deposition and patterning for the pads <NUM> may be skipped and the mask deposited directly on the probe device <NUM>. Gaps are imaged into the mask in the step <NUM>.

In the step <NUM>, the spike material <NUM> is deposited onto the mask and into the gaps to form the spikes <NUM>. The spike material <NUM> may be deposited by evaporation. The deposition results in the formation of knife-edge microstructures in the gaps. An over-coat material may optionally be formed over the spikes <NUM> using a photoresist coating, a photoresist patterning, and an evaporation of the over-coat material. The spike material <NUM> remaining on the mask and the mask itself are removed in the step <NUM> to leave the spikes <NUM> exposed and protruding away from the second surface <NUM> of the probe device <NUM>.

Referring to <FIG>, a schematic perspective diagram of an example structure of a spike <NUM> is shown in accordance with one or more exemplary embodiments. The spike <NUM> generally has a cone shape <NUM>. The spike <NUM> comprises an inner layer <NUM> optionally covered by an over-coat layer <NUM>. The inner layer <NUM> may be selected from among the spike materials <NUM>. The over-coat layer <NUM> may be selected from among the spike materials <NUM>. In various embodiments, the over-coat layer <NUM> is included to prevent a metallurgical bond from forming between the spike <NUM> and the test patterns <NUM> due to the compressions during tilt adjustments and device testing.

A taper angle of the spikes <NUM> is controlled by the metal used in the fabrication. Examples of taper angles include gold (<NUM>°), titanium (<NUM>°), and platinum (<NUM>°). Other metals may be used to achieve other taper angles. The spikes <NUM> may be constructed with narrow tip radii of approximately <NUM> nanometers (nm) and larger, and a small base diameter of <NUM> micrometers (µm) and larger (e.g., ≥<NUM>). Other tip radii and/or pitch may be implemented to meet the design criteria of a particular application.

Referring to <FIG>, a schematic plan diagram of an example implementation of a position sensor layout <NUM> is shown in accordance with one or more exemplary embodiments. The position sensor layout <NUM> illustrates a first-axis position sensor <NUM> and second-axis position sensor <NUM>. The first-axis (e.g., an x-axis) position sensor <NUM> is oriented orthogonal to the second-axis (e.g., a y-axis) position sensor <NUM>. In various embodiments, each position sensor <NUM> and <NUM> are divided into two sub-sensors <NUM>, with a major axis aligned parallel to each other to extend the range of by a factor of two. The position sensors <NUM> and <NUM> include two position traces <NUM> on the position device <NUM> and corresponding resistor networks <NUM> on the device-under-test <NUM>. Spikes <NUM> are formed on the position traces <NUM>. In various embodiments, the position sensors <NUM> and <NUM> may implement electronic Vernier sensors.

While the probe device <NUM> is in contact with the device-under-test <NUM>, the spikes <NUM> may make physical and electrical contact the resistor networks <NUM>. A position resistance <NUM> measured by the meter <NUM> (<FIG>) across the position traces <NUM> varies based on where the spikes <NUM> contact the resistor networks <NUM>. The position resistance <NUM> of the first-axis position sensor <NUM> may indicate a first horizontal alignment <NUM>. The position resistance <NUM> of the second-axis position sensor <NUM> may indicate a second horizontal alignment <NUM>. Optimizing the resistance value by moving the probe device <NUM> relative to the device-under-test <NUM> allows for precise alignment with an approximately <NUM> resolution over a range of several µm (e.g., approximately <NUM> to <NUM>) in each axis.

Referring to <FIG>, a schematic perspective diagram of an example implementation of a touchdown sensor <NUM> is shown in accordance with one or more exemplary embodiments. Two touchdown sensor <NUM> are illustrated in the figure. Each touchdown sensor <NUM> generally includes a pad <NUM> and at least two spikes <NUM>. The at least two spikes <NUM> may be separated from each other by an approximately <NUM> to <NUM> pitch.

While the probe device <NUM> is in contact with the device-under-test <NUM>, the meter <NUM> (<FIG>) may measure a touchdown conductance <NUM> through the at least two spikes <NUM> and the corresponding pad <NUM>. A measured conductance of zero indicates that one or both of the at least two spikes <NUM> are not in electrical contact with the corresponding pad <NUM>. Therefore, the tilt and/or alignment of the probe device <NUM> relative to the device-under-test <NUM> may be changed before initially testing of the device-under-test <NUM>. A positive (e.g., >zero) touchdown conductance <NUM> through the at least two spikes <NUM> and the corresponding pad <NUM> generally indicates a clean electrical contact with the pad <NUM>. Therefore, a main spike (e.g., either spike <NUM>) of the at least two spikes <NUM> may be used in testing of the device-under-test <NUM>.

Referring to <FIG>, a schematic diagram of example tilt angle sensor states <NUM> is shown in accordance with one or more exemplary embodiments. The tilt angle sensor states <NUM> include a first state <NUM> after a first touchdown, a second state <NUM> after a second touchdown, and a third state <NUM> after a third touchdown. Example adjustments of the angles (phi and theta) of the spherical positioner <NUM> (<FIG>) used to correct the tilt angle error, and an applied force (in Newtons (N)) per millimeter (mm) squared are provided in Table I as follows:.

The first state <NUM> illustrates an initial touchdown (e.g., a low-force touchdowns of approximately 15uN-50uN/spike) with an initial condition where the probe device <NUM> is not adequately parallel to the device-under-test <NUM> (<FIG>). The low-force touchdowns generally allow electrical measurements of the tilt angle sensor contact state without bonding to the device-under-test <NUM>. The tilt angle control aids in delineating probing (elastic) and bonding (plastic) regime interaction between the probe device <NUM> and device-under-test <NUM> as non-parallel contact orientations results in non-uniform pressure distributions. As illustrated in the first state <NUM>, some of the tilt angle sensors <NUM> (circle symbols) indicate closed contacts with the corresponding test patterns <NUM>. Other tilt angle sensors <NUM> (plus symbols) indicate open contacts. An arrow indicates a global tilt angle <NUM> between the device-under-test <NUM> and the probe device <NUM>.

The global tilt angle <NUM> is used to determine appropriate adjustments to the die bonder <NUM> to improve the parallelization between the device-under-test <NUM> and the probe device <NUM>. In the second state <NUM>, the circle symbols indicate that each tilt angle sensor <NUM> has contacted a corresponding test pattern <NUM>, and so no global tilt angle <NUM> is illustrated.

The final touchdown in the third state <NUM> was performed at probing force levels. The third state <NUM> showed fully contacted tilt angle sensors <NUM> and <NUM>% contact yields for multiple (e.g., five) daisy-chain test arrays (e.g., <NUM>,<NUM> element chains per array) fabricated on the device-under-test <NUM>.

A parallelism of the die bonder <NUM> is generally specification at approximately ±<NUM> microradians. Such level of tilt error corresponds to a ±<NUM> height variation over a <NUM> distance (typical of the chip sets) and/or to a ±<NUM> height variation over a <NUM> distance (typical of the reticle sizes). However, backside surface imperfections (e.g., particles and dicing micro-cracks) may cause pressure-dependent height variation during the probing and result in the tilt angle errors. To improve the parallelism between the spikes <NUM> on the probe device <NUM> and the device-under-test <NUM> during probing, feedback control (e.g., manually or automated) by using the on-chip tilt angle sensor measurements to correct tilt errors during the low-force touchdowns.

The spherical positioner <NUM> (<FIG>) is used to adjust the phi (North-South) and the theta (East-West) spherical angles of the upper arm relative to the chuck based on tilt conditions derived by monitoring the unit contactor states. The low-force touchdowns are used to sense the tilt angle sensor states and adjustments are subsequently applied to the spherical positioner <NUM> for subsequent touchdowns, until the errors are eliminated or brought to within acceptably small limits. After the tilt errors are nulled (sensed by <NUM>% reported closed states), an appropriate level of force is applied for probing the device-under-test <NUM>.

Referring to <FIG>, an image <NUM> of an example resilient pillar <NUM> is shown in accordance with one or more exemplary embodiments. The image <NUM> illustrates a scanning electron micrograph of a resilient pillar <NUM> disposed between a spike <NUM> (not shown) and the support pads <NUM>. One resilient pillar <NUM> may be formed for each spike <NUM> of the probe device <NUM>. Each resilient pillar <NUM> may be fabricated using elastomer layers, such as polyimide (Young's modulus <NUM> GPa), to act as spring-like cushion layer. In various embodiments, the elastomer layers may be the polyimide, Polydimethylsiloxane (PDMS), Polymethyl methacrylate (PMMA), Polyethylene, Polytetrafluoroethylene (PTFE), and/or Polyvinyl chloride (PVC). Each resilient pillar <NUM> may be approximately <NUM> tall.

To ensure the operation in the elastic regime, finite-element analysis modeling was used to provide guidance on the choice of thickness and modulus of the polymer layers. The conclusions of experimental tests utilizing the tilt angles sensors <NUM> to measure the elastomer performance were that under typical applied forces (<85µN/probe) for spike probing, approximately less than <NUM> microradian angle corrections were available. Greater angle corrections were unfavorable due to the relatively high modulus and reasonably small thickness (<NUM>) of the polyimide materials (a limitation of the available materials). The modeling showed that approximately <NUM> microradians passive tilt correction may be possible with greater polyimide thicknesses or the use of lower modulus polymer layers (e.g., PDMS: Young's Modulus <NUM> megapascals (MPa)). Employing the resilient pillars <NUM> means that fewer tilt angle sensors <NUM> may be placed around the periphery of the probe device <NUM> as high-yield probe contacts may be achieved without determining exact tilt angles to correct the tilt errors.

While probing was performed with test arrays with relatively uniform, thin contacts (e.g., <NUM>) directly on silicon substrates, foundry-derived chipsets may have larger pad-to-pad height variations. To address the local topography nonuniformities, the spikes <NUM> may be formed on elastomer pillars to allow independent suspension of the individual spike-to-test pattern probe contacts.

Referring to <FIG>, a flow diagram of an example method <NUM> to aid in a calibration of the probing system <NUM> is shown in accordance with one or more exemplary embodiments. The method <NUM> includes steps <NUM> to <NUM>, as illustrated. The sequence of steps is shown as a representative example. Other step orders may be implemented to meet the criteria of a particular application. The method (or process) <NUM> is implemented with the probing system <NUM> with the device-under-test <NUM> and the probe device <NUM>.

In the step <NUM>, the device-under-test <NUM> is mounted to the bottom chuck <NUM> with the first surface <NUM> of the device-under-test <NUM> facing outward. The probe device <NUM> is mounted to the top chuck <NUM> with the second surface <NUM> facing the first surface <NUM> of the device-under-test <NUM> in the step <NUM>. The spherical positioner may be adjusted to a course parallelization in the step <NUM>. In the step <NUM>, the probe device <NUM> is aligned to the device-under-test <NUM> in the x-axis and the y axis.

In the step <NUM>, the probe device <NUM> and the device-under-test <NUM> are pressed together with the first force 136a to cause at least a subset of the spikes <NUM> of the tilt angle sensors <NUM> to contact the test patterns <NUM>. A number of electrical connections formed between the tilt angle sensors <NUM> and the test patterns <NUM> is measured in the step <NUM>. Determining the number of electrical connections generally includes measuring total tilt conductances <NUM> through the tilt angle sensors <NUM> and the test patterns <NUM> in the step <NUM>. Each tilt angle sensor <NUM> includes two sets of spikes <NUM>. Each test pattern <NUM> includes pattern traces <NUM>. Each contacted pattern trace <NUM> contributes a respective tilt conductance <NUM> to a corresponding total tilt conductance <NUM>. The total tilt conductances <NUM> are reported in the step <NUM> from the meter <NUM> to the processor <NUM>.

In the step <NUM>, the processor <NUM> determines a first offset angle 130c and a second offset angle 130d between the first surface <NUM> of the device-under-test <NUM> and the second surface <NUM> of the probe device <NUM> based on the total tilt conductances <NUM> (e.g., the number of electrical connections). Determining the first offset angle 130d generally includes receiving the total tilt conductances <NUM> at the processor <NUM> in the step <NUM>. In the step <NUM>, the processor <NUM> determines the first offset angle 130c with a first group <NUM> of the tilt angle sensors <NUM> that are oriented in the first direction 134c. In the step <NUM>, the processor <NUM> determines the second offset angle 130d with the second group <NUM> of the tilt angle sensors <NUM> that are oriented in the second direction 134b.

The probe device <NUM> is separated from the device-under-test <NUM> in the step <NUM>. The spherical positioner <NUM> is adjusted in the step <NUM> in one or more rotational axes in response to the first offset angle 130c and the second offset angle 130d to change a parallelism between the first surface <NUM> of the device-under-test <NUM> and the second surface <NUM> of the probe device <NUM>. Adjusting the rotational axes may include controlling the adjustment of the spherical positioner with the processor <NUM> in the step <NUM> in response to the first offset angle 130c and the second offset angle 130d.

After the spherical positioner <NUM> is adjusted, the probe device <NUM> and the device-under-test <NUM> are compressed together in the step <NUM> with the second force 136b. If the subsequent parallelization is acceptable, the device-under-test <NUM> may be electrically tested in the step <NUM> by the computer <NUM>.

Referring to <FIG>, a flow diagram of an example method <NUM> to determine a touchdown status is shown in accordance with one or more exemplary embodiments. The method generally includes steps <NUM> to <NUM>, as illustrated. The sequence of steps is shown as a representative example. Other step orders may be implemented to meet the criteria of a particular application.

In the step <NUM>, the probe device <NUM> and the device-under-test <NUM> are compressed together with a force (e.g., the first force 136a). A touchdown conductance through each of at least two probe tips <NUM> tips and a respective test pad <NUM> is measured in the step <NUM>. A check is performed in the step <NUM> to determine if the touchdown conductance greater than zero. If not, the compression is increased in the step <NUM> and the touchdown conductance is measured again. Once the touchdown conductance is greater than zero testing of the device-under-test <NUM> may begin in the step <NUM>.

Referring to <FIG>, a flow diagram of an example method <NUM> for X-Y alignment is shown in accordance with one or more exemplary embodiments. The method generally includes steps <NUM> to <NUM>, as illustrated. The sequence of steps is shown as a representative example. Other step orders may be implemented to meet the criteria of a particular application.

In the step <NUM>, the probe device <NUM> and the device-under-test <NUM> are compressed together with a force (e.g., the first force 136a). The position resistances <NUM> are measured in the step <NUM> through the position sensors <NUM> and <NUM> and the corresponding resistor networks <NUM>. The first horizontal alignment <NUM> and a second horizontal alignment <NUM> between the device-under-test <NUM> and the probe device <NUM> is determined in the step <NUM> based on the position resistances <NUM>.

In the step <NUM>, the probe device <NUM> is separated from the device-under-test <NUM>. The relative X-Y position of the probe device <NUM> is adjusted in the step <NUM> based on the first horizontal alignment and the second horizontal alignment. In the step <NUM>, the probe device <NUM> and the device-under-test <NUM> are compressed together with another force (e.g., the second force 136b). The steps of measuring, determining, and adjusting may be repeated until the probe device <NUM> is sufficiently aligned to the device-under-test <NUM> for further processing.

The fabrication of the spikes <NUM> is useful in the tilt angle measurements, X-Y alignment, and touchdown measurements, and generally outperforms standard methods. The fabrication process provides advantages of fine-pitch arrays (e.g., less than <NUM>). The fabrication process enables arrays with low tip height variation (e.g., down to <<NUM>) because the spike heights are made with a self-limiting process that enables high fidelity replication. The sharp tips (e.g., approximately <NUM> dimensions) are integral to the fabrication process as the photoresist opening is closed as the titanium is deposited. The fabrication process provides an ability to fabricate a variety of different metals with high hardness (e.g., ><NUM> gigapascals (GPa)). The fabrication process also provides an ability to engineer the hardness by layering the spike structure (e.g., titanium and tungsten layered with softer metals such as gold, platinum, and palladium) and/or apply an over-coat to the spikes to improve its release after indentation and prevent metallurgical bonds to form (e.g., natural oxides help to prevent metallurgical bonds to indented material layers or bumps).

The probing system <NUM> provides a method and a probe device that includes fine-pitch arrays of high hardness, conically shaped needle-like microstructures (spikes) that provides fine tilt and position measuring capabilities. The probing system <NUM> includes tilt angle sensors for fine-pitch (≤ <NUM> pitch) array probing. Various embodiments provide a measurement of local contact states and global tilt angles during touchdown operations between a probe array of spikes and a device-under-test. Fine-pitch probing with densities ><NUM><NUM> contacts/mm<NUM> involves a high degree of parallelism between the probe head and device-under-test surfaces to ensure high yield contact. However, the fine-pitch dimensions constrain the employable probe-delivery mechanisms (cantilevers, springs, etc.) to generate enough displacement across the probe head area (e.g., chip or reticle size) to overcome inherent platform misalignments (e.g., parallelism tolerances) and process related factors (e.g., backside irregularities including particles and micro-cracks, and clamping distortions) that contribute to tilting errors in the probing process. Given such constraints, the probing system <NUM> provides a compact set of integrated sensors for fine-pitch area array probers that provides local contact sensing and global tilt angle measurements during low-force touchdowns, and feedback signals used by the prober platform (precision hardware) to correct non-parallel orientations.

The tilt angle sensors include a set of distributed touchdown sensing units across the probe head, each with a set of redundant sensors (e.g., bridging contactor links with spikes on the probe head side that are shorted by contact lines on the device-under-test). The sensing units are positioned, often uniformly, around a perimeter as well as in the center of the probe array. The arrangement and numbers of the sensing units determine the accuracy of the tilt angle measurement. The sensing units provide information on the physical contact state of a particular location at touchdown of the probe array on the device-under-test and, taken collectively, provide a measurement of the global tilt angle. The tilt angles are corrected by the prober platform using the information provided by the tilt angles sensors. The prober platform thus serves multiple functions, including precision tilt angle control as well as a station for holding the probe device and the device-under-test (die or wafer), providing controlled force levels during probe touchdowns, and precise positioning and alignment of the probe and device-under-test fine-pitch layouts.

Various embodiments provides improved tilt angle sensors that support fine-pitch area array probing. The tilt angle sensors perform local contact measurements to determine global tilt conditions. Elimination of the tilt angles helps achieve reliable probe array touchdowns between probe arrays of spikes and devices-under-test. Advantages of the techniques disclosed herein may include, but are not limited to, sensing and elimination of tilt angle errors in fine-pitch area array probing, small form-factor angle sensors that utilize spike-based probes capable of fine-pitch (≤ <NUM>) contact probes and compact footprints, applications to a range of fine-pitch devices-under-test without modification, low force sensor operation that avoids contact pad damage during pre-alignment and probing procedures, allowing multiple touchdowns to optimize correction of tilt errors, an ability to sense and correct tilt angle errors under applied force, real-time local contact and global tilt angle measurements under probe touchdown operations, and instant pre-examination of engaging local pressure and uniformity to ensure bonding quality during multi-chip bonding.

This disclosure is susceptible of embodiments in many different forms. Representative embodiments of the disclosure are shown in the drawings and will herein be described in detail with the understanding that these embodiments are provided as an exemplification of the disclosure, not limitations of the broad aspects of the disclosure. To that extent, elements and limitations that are described, for example, in the Abstract, Background, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference or otherwise.

According to the present disclosure, a probing system, a method and a calibration kit as defined in the independent claims are provided. Further embodiments of the invention are defined in the dependent claims.

For purposes of the present detailed description, unless specifically disclaimed, the singular includes the plural and vice versa. The words "and" and "or" shall be both conjunctive and disjunctive. The words "any" and "all" shall both mean "any and all", and the words "including," "containing," "comprising," "having," and the like shall each mean "including without limitation. " Moreover, words of approximation such as "about," "almost," "substantially," "approximately," and "generally," may be used herein in the sense of "at, near, or nearly at," or "within <NUM>-<NUM>% of," or "within acceptable manufacturing tolerances," or other logical combinations thereof. Referring to the drawings, wherein like reference numbers refer to like components.

Claim 1:
A probing system (<NUM>) comprising:
a device-under-test (<NUM>) that includes a plurality of test patterns (<NUM>) on a first surface (<NUM>);
a probe device (<NUM>) that includes a plurality of tilt angle sensors (<NUM>), wherein the plurality of tilt angle sensors (<NUM>) include a plurality of spikes (<NUM>) that protrude from a second surface (<NUM>) of the probe device (<NUM>); and
a die bonder (<NUM>) having a spherical positioner (<NUM>) that is adjustable in a plurality of rotational axes (<NUM>), wherein the die bonder (<NUM>) is operational to:
mount the device-under-test (<NUM>) with the first surface (<NUM>) facing outward;
mount the probe device (<NUM>) with the second surface (<NUM>) of the probe device (<NUM>) facing the first surface (<NUM>) of the device-under-test (<NUM>);
compress the probe device (<NUM>) and the device-under-test (<NUM>) together with a first force (136a) that causes a subset of the plurality of spikes (<NUM>) to contact the plurality of test patterns (<NUM>);
measure a number of electrical connections formed between the plurality of tilt angle sensors (<NUM>) and the plurality of test patterns (<NUM>);
determine a first offset angle (130c) and a second offset angle (130d) between the first surface (<NUM>) of the device-under-test (<NUM>) and the second surface (<NUM>) of the probe device (<NUM>) based on the number of electrical connections;
separate the probe device (<NUM>) from the device-under-test (<NUM>); and
adjust the spherical positioner (<NUM>) in one or more of the plurality of rotational axes (<NUM>) in response to the first offset angle (130c) and the second offset angle (130d) to change a parallelism between the first surface (<NUM>) of the device-under-test (<NUM>) and the second surface (<NUM>) of the probe device (<NUM>).