Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
  • G01R31/2851—Testing of integrated circuits [IC]
  • G01R31/2886—Features relating to contacting the IC under test, e.g. probe heads; chucks
  • G01R31/2891—Features relating to contacting the IC under test, e.g. probe heads; chucks related to sensing or controlling of force, position, temperature

Definitions

• the present invention relates, in general, to wafer probers, and, more particularly, to an apparatus and method for correcting the parallelism between the probe card and the chuck plate of a wafer prober.
• a wafer prober is a device for connecting chips on a wafer to a tester so as to test the chips on the wafer.
• a wafer prober 100 includes a probe card 102, a wafer transfer device 104, a chuck plate 106, a chuck transfer device 108, and a control device 110.
• the wafer transfer device 104 loads a wafer, on which a plurality of chips is formed, on the chuck plate 106.
• the chuck plate 106 is moved in X, Y and Z directions through the chuck transfer device 108 so that a plurality of probes provided on the probe card 102 is aligned to come into contact with the pads of the chips provided on the wafer 112.
• a tester 114 When the plurality of probes comes into contact with the pads of the plurality of chips, respectively, a tester 114 provides a test signal based on a predetermined program to the chips of the wafer 112 through the probe card 102. The chips of the wafer 112 provide output signals attributable to the test signal to the tester 114 through the probe card 102. Accordingly, the tester 114 performs a test on the chips of the wafer 112.
• an object of the present invention is to provide an apparatus and method for correcting the parallelism between the probe card and the chuck plate of a wafer prober, which allow the probe card and the chuck plate to come into parallel contact with each other by tilting the chuck plate according to the tilt of the probe card of the wafer prober.
• the present invention provides a method of correcting parallelism between a probe card and a chuck plate of a wafer prober, comprising the steps of measuring a tilt of the probe card; generating a plurality of pieces of displacement information, indicating intervals between a base for vertically supporting the chuck plate and the chuck plate to correspond to the measured tilt of the probe card, with respect to a plurality of first preset locations between the base and the chuck plate; and individually driving a plurality of actuators installed at second preset locations between the base and the chuck plate so that the base and the chuck plate become far away from each other or become close to each other in different degrees until a plurality of pieces of sensed displacement information, output from a plurality of displacement sensors installed at the first preset locations between the base and the chuck plate by sensing intervals between the base and the chuck plate at installation locations thereof, tracks the plurality of pieces of displacement information, respectively, wherein the chuck plate tracks the tilt of the probe card, and thus the
• the present invention is advantageous in that a probe card and a chuck plate come in parallel contact with each other by tilting the chuck plate of a wafer prober to correspond to the tilt of the probe card, thus improving the efficiency of a test on chips on a wafer.
• FIG. 1 is a diagram showing the schematic construction of a typical wafer prober
• FIG. 2 is a block diagram showing a chuck plate tilting device according to an embodiment of the present invention.
• FIGS. 3 and 4 are diagrams showing a chuck plate tilting device according to an embodiment of the present invention.
• FIG. 5 is a diagram showing the detailed construction of the control device of a chuck plate tilting device according to an embodiment of the present invention.
• FIGS. 6 and 7 are flowcharts showing the processing of a chuck plate tilting device according to an embodiment of the present invention. Best Mode for Carrying out the Invention
• a method of correcting parallelism between a probe card and a chuck plate of a wafer prober includes the steps of measuring a tilt of the probe card; generating a plurality of pieces of displacement information, indicating intervals between a base for vertically supporting the chuck plate and the chuck plate to correspond to the measured tilt of the probe card, with respect to a plurality of first preset locations between the base and the chuck plate; and individually driving a plurality of actuators installed at second preset locations between the base and the chuck plate so that the base and the chuck plate become far away from each other or become close to each other in different degrees until a plurality of pieces of sensed displacement information, output from a plurality of displacement sensors installed at the first preset locations between the base and the chuck plate by sensing intervals between the base and the chuck plate at installation locations thereof, tracks the plurality of pieces of displacement information, respectively, wherein the chuck plate tracks the tilt of the probe card, and thus the chuck plate and the probe card are arranged in
• a wafer prober includes a chuck plate tilting device 200, a main control device 222, an imaging device 224, and a memory unit 226.
• the chuck plate tilting device 200 tilts a chuck plate to correspond to the tilt of a probe card in compliance with a tilt command from the main control device 222, thus enabling the chuck plate to come into parallel contact with the probe card.
• the main control device 222 receives information obtained by imaging the probe card through the imaging device 224, detects the degree of tilting of the probe card, that is, a tilt, generates a tilt command required to tilt the chuck plate to correspond to the tilting degree of the probe card, and transmits the tilt command to the chuck plate tilting device 200.
• the tilt command includes pieces of first to third displacement information which correspond to first to third displacement sensors 204 to 208 of the chuck plate designated to correspond to the tilt of the probe card.
• the pieces of first to third displacement information may be obtained in such a way that pieces of first to third displacement information of the first to third displacement sensors 204 to 208, corre- sponding to respective tilts, are obtained in advance through experiments at the time of manufacturing the wafer prober and are stored in the memory unit 226, or in such a way that the pieces of first to third displacement information are calculated through formula acquired from the correlation between the pieces of first to third displacement information of the first to third displacement sensors 204 to 208 corresponding to the tilts.
• the memory unit 226 stores therein various types of information including the control programs of the main control device 222, especially, tilt commands composed of pieces of first to third displacement information of the first to third displacement sensors 204 to 208 corresponding to respective tilts of the probe card.
• the chuck plate tilting device 200 includes a control device 202, the first to third displacement sensors 204 to 208, an Analog-to-Digital Converter (ADC) 210, a Digital- to- Analog Converter (DAC) 212, first to third actuators 214 to 218, and a communication module 220.
• ADC Analog-to-Digital Converter
• DAC Digital- to- Analog Converter
• the first to third displacement sensors 204 to 208 and the first to third actuators 214 to 218 are installed between the chuck plate 300 and a base 302, as shown in FIGS. 3 and 4.
• the base 302 vertically supports the chuck plate 300, wherein tools for vertically supporting the chuck plate 300 are collectively called a Z axis.
• the first to third displacement sensors 204 to 208 are installed at three equal division locations of the rear surface of the chuck plate 300 coming into contact with the base 302, respectively. Further, the first to third actuators 214 to 218 are installed at other three equal division locations of the rear surface of the chuck plate 300 coming into contact with the base 302.
• Each of the first to third displacement sensors 204 to 208 senses a vertical interval between the base 302 and the chuck plate 300 at its own installation location, and provides a sensed signal attributable to the sensing operation to the ADC 210.
• the ADC 210 converts the first to third sensed signals output from the first to third displacement sensors 204 to 208 into pieces of first to third sensed displacement information, and provides the first to third sensed displacement information to the control device 202.
• the control device 202 generates first to third drive commands for the first to third actuators 214 to 218, which allow the pieces of first to third sensed displacement information, output from the first to third displacement sensors 204 to 208, to track the pieces of first to third displacement information for the first to third displacement sensors 204 to 208 that are included in the tilt command output from the main control device 222.
• the first to third drive commands for the first to third actuators 214 to 218 are converted into first to third drive signals for the first to third actuators 214 to 218 through the DAC 212 and are provided to the first to third actuators 214 to 218.
• the first to third actuators 214 to 218 increase or decrease the vertical interval between the base 302 and the chuck plate 300 in different degrees at the installation locations thereof in response to the first to third drive signals output from the control device 202, thus enabling the base 302 and the chuck plate 300 to become far away from each other or to become close to each other in a vertical direction. Accordingly, the chuck plate 300 is tilted to correspond to the tilt of the probe card.
• the communication module 220 performs communication between the main control device 222 and the control device 202.
• the control device 202 includes a comparator 500 and a Proportional-
• the comparator 500 compares the pieces of first to third displacement information with the pieces of first to third sensed displacement information output from the first to third displacement sensors 204 to 208, and provides the results of the comparison to the PID controller 502.
• the PID controller 502 generates first to third drive commands for the first to third actuator 214 to 218 so that all of the results of the comparison become "0", and then provides the first to third drive commands to the first to third actuator 214 to 218, respectively.
• control device 202 generates the first to third drive commands required to control the first to third actuators 214 to 218 so that the pieces of first to third sensed displacement information output from the first to third displacement sensors 204 to 208 track the pieces of first to third displacement information, respectively.
• the main control device 222 notifies the control device 202 of the chuck plate tilting device 200 of an initialization command in an initialization process at step 600.
• the main control device 222 detects the tilt of the probe card, that is, the degree of tilting of the probe card, through the imaging of the probe card performed by the imaging device 224 at step 602.
• the main control device 222 reads from the memory unit 226 a tilt command for the chuck plate, corresponding to the tilting degree of the probe card, that is, pieces of first to third displacement information which the pieces of first to third sensed displacement information output from the first to third displacement sensors 204 to 208 must track, configures a chuck plate tilt command from the first to third displacement information, and transmits the chuck plate tilt command to the chuck plate tilting device 200 at step 604.
• the control device 202 initializes the first to third actuators 214 to 218 in response to an initialization command from the main control device 222 at steps 700 and 702.
• the control device 202 drives the first to third actuators 214 to 216 so that respective pieces of first to third sensed displacement information output from the first to third displacement sensors 204 to 208 track the pieces of first to third displacement information included in the chuck plate tilt command.
• control device 202 compares the pieces of first to third displacement information for the first to third displacement sensors 204 to 208, provided by the main control device 222, with the first to third sensed displacement values, actually sensed by the first to third displacement sensors 204 to 208, respectively, generates drive commands for the first to third actuators 214 to 218 which cause the pieces of first to third displacement information to become identical to the first to third sensed displacement values, and provides the drive commands to the first to third actuators 214 to 218.
• the present invention is advantageous in that a probe card and a chuck plate come in parallel contact with each other by tilting the chuck plate of a wafer prober to correspond to the tilt of the probe card, thus improving the efficiency of a test on chips on a wafer.

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• 2008
  • 2008-08-20 KR KR1020080081326A patent/KR101007871B1/ko active IP Right Grant
  • 2008-11-03 CN CN200880130761.1A patent/CN102124552B/zh active Active
  • 2008-11-03 WO PCT/KR2008/006461 patent/WO2010021427A1/en active Application Filing
• 2009
  • 2009-08-06 TW TW98126531A patent/TWI403728B/zh active

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