Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/22—Secondary treatment of printed circuits
  • H05K3/26—Cleaning or polishing of the conductive pattern
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R3/00—Apparatus or processes specially adapted for the manufacture or maintenance of measuring instruments, e.g. of probe tips
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
  • G01R1/02—General constructional details
  • G01R1/06—Measuring leads; Measuring probes
  • G01R1/067—Measuring probes
  • G01R1/06711—Probe needles; Cantilever beams; "Bump" contacts; Replaceable probe pins
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
  • G01R1/02—General constructional details
  • G01R1/06—Measuring leads; Measuring probes
  • G01R1/067—Measuring probes
  • G01R1/073—Multiple probes
  • G01R1/07307—Multiple probes with individual probe elements, e.g. needles, cantilever beams or bump contacts, fixed in relation to each other, e.g. bed of nails fixture or probe card
  • G01R1/07342—Multiple probes with individual probe elements, e.g. needles, cantilever beams or bump contacts, fixed in relation to each other, e.g. bed of nails fixture or probe card the body of the probe being at an angle other than perpendicular to test object, e.g. probe card

Definitions

• the present invention relates to the field of semiconductor testing equipment and, more specifically, to the field of probe cards for semiconductor test systems.
• wafer sort In the manufacture of semiconductor devices, it is advisable that such components be tested at the wafer level to evaluate their functionality.
• the process in which die on the wafer are tested is commonly referred to as "wafer sort". Testing and determining design flaws at the die level offers several advantages. First, it allows designers to evaluate the functionality of new devices during development. Increasing packaging costs also make wafer sorting a viable cost saver, in that the reliability of each die on the wafer may be tested before incurring the high costs of packaging.
• Wafer sorting typically involves the use of probing technology wherein a probe card containing probing features engages the die so as to connect the bond pads of the die to a tester.
• probing technology wherein a probe card containing probing features engages the die so as to connect the bond pads of the die to a tester.
• microprocessor performance is becoming limited by chip to package interconnections.
• Three primary processes - wirebonding (WB), tape automated bonding (TAB), and controlled collapse chips connection (C4) - are used to interconnect a chip to a package.
• the C4 technology utilizes solder bumps, comprised of mostly lead and some tin, to interconnect the chip to a package.
• solder bumps comprised of mostly lead and some tin
• FIG. 1 shows a solder bump 10 with an oxide layer 12, typically a non-conductive film formed on the surface of exposed lead and tin.
• scrub applies to any non-conductive layer that produces a barrier between the probing features of a probe card and the base metal of a bond pad.
• the purpose of the scrub is to break through the non-conductive layer in order to establish good electrical contact between the probing features and the base metal of the bond pads or solder bumps. Scrub occurs when the handler forces the wafer, and, subsequently, the bond pads of a die, against the probe features on the probe card causing the probe feature to deflect.
• the scrub is generated by a small horizontal movement of each probe feature across the surface of each corresponding bond pad as the probing features deflect. As the probing features move across the bond pads or solder bumps, they penetrate the non- conductive oxide layer thereby establishing good electrical contact between the probing features and the bond pads or solder bumps.
• FIGS 2A-2C roughly demonstrate the wafer sort process.
• Figure 2A illustrates a portion of probe card 20 with microspring probing features 22 coupled to multi-layer ceramic space transformer 21 and probing feature tips 24.
• microspring tips 24 touch down on solder bumps 26 which are part of integrated circuit device 28.
• the lead tin alloy is extremely malleable and easily adheres to the metal or metal alloy probing feature.
• Figure 2C depicts microsprings 22 following a wafer sort during which solder deposits 29 have accumulated on microsprings 22 bridging the small gap between microsprings.
• the probing features of probe cards are spaced very close together.
• a microspring probe card may have 1,500 microsprings (40 mils tall; 5.5-6 mils diameter) with a minimum pitch (spacing) between the microsprings of 225 micron.
• Figures 3, 4 and 5 depict additional types of probing features although it is appreciated that other types of probing features are available.
• Figure 3 illustrates a portion of a probe card 30 with probing features 34 contained within a tubular housing. The probing feature or "beam" deflects upon contact with a solder bump by buckling or bending.
• the probing features are coupled to a multi-layer ceramic space transformer 31.
• a third example of a probing feature is shown in Figure 4, which illustrates a "cantilever needle” probe card 40.
• the cantilever needles 42 are connected to a printed circuit board 41 and held in place by an epoxy ring 43.
• Figure 5 depicts a cross sectional view of a "membrane" probe card 45 with probing features 48 connected to a flexible printed circuit 46.
• the lead tin composition on the surface of the solder bump easily adheres to the metal or metal alloy probing feature without regard to the shape or type of probing feature utilized during the wafer sort process.
• Stray particle and solder buildup contributes to high contact resistance between the probing feature's tip and the solder bump.
• High contact resistance causes inaccurate voltage levels during device testing due to the non- conductive layer produced across the probe tip. This may cause a device to incorrectly fail, resulting in unnecessarily lower test yields.
• the accumulated buildup of solder deposits may bridge the small gap between probing features resulting in shorts or leakage currents, again, leading to unnecessarily lower test yields.
• the solder buildup may cause the probing feature to be lodged within the lower die plate. In order to ensure accurate wafer sort test results, deposits that adhere to a probing feature during wafer sort must be removed.
• FIG. 6 depicts a portion of probe card 50 with probing features 54 extending from multi-layer ceramic space transformer 51. After deposits 54 build up on microsprings 52 during wafer sort, tips 56 of microsprings 52 are brought into contact with an abrasive paper 58. By moving probe card 50 in relation to abrasive paper 58, deposits 54 are removed from tips 56, however deposits 54 remain along the length of microspring 52, due to the adhesive nature of the solder. Typically probing features are abrasively cleaned once every 100 die.
• the abrasive cleaning method is undesirable because the method (i) results in excessive erosion of the probing feature which dramatically reduces the lifetime of the probe card; (ii) only removes deposits from the tips of the probing features allowing the deposits to accumulate on the non-tip portion of the probing feature; and (iii) is less effective for removing solder from dirty probing features which have remained on a prober for an extended period of time where the solder has oxidized. Because the abrasive paper is flat and relatively non-compliant, the abrasive cleaning method is not suitable for removing deposits from the non-tip portion of the probing feature.
• Tungsten cantilever needle probing features are typically placed in an acidic solution which dissolves the probing feature thereby removing the aluminum or lead- tin oxide buildup on the probing feature.
• the problem with this method is that the lifetime of the probe card is dramatically reduced since the tip of the probing feature is partially dissolved as it is exposed to the acid-based cleaning composition.
• a method for removing deposits from a probing feature of a probe card includes the step of exposing the probing feature of a probe card to a composition that chemically reacts with deposits on the probing feature of a probe card to remove the deposits from the probing feature without substantially reacting with the probing feature itself.
• the probe features of a probe card are cleaned by exposing the probe features to a composition comprising acetic acid, hydrogen peroxide, and deionized water.
• Figure 1 illustrates a cross-sectional view of a typical solder bump.
• Figure 2A presents a side view of a portion of a probe card with microspring probing features.
• Figure 2B presents the probing features illustrated in Figure 2A touching down on solder bumps.
• Figure 2C presents the probing features illustrated in Figure 2B with solder deposits thereon.
• Figure 3 presents a side view of a portion of a probe card with buckling beam probing features.
• Figure 4 presents a side view of a portion of a cantilever-needle probe card.
• Figure 5 presents a side view of a portion of a membrane probe card.
• Figure 6 presents a prior art method of cleaning the probing features of a probe card.
• Figure 7 presents a flowchart of one embodiment of the present invention.
• Figure 8A show the probing features of a probe card being cleaned in accordance with one embodiment of the present invention.
• Figure 8B shows the probing features of a probe card being cleaned in another embodiment of the present invention.
• Figure 9 presents a flow chart of another embodiment of the present invention.
• a method for removing deposits from a probing feature of a probe card includes the step of exposing the probing feature to a composition that chemically reacts with deposits on the probing feature to remove the deposits from the probing feature without substantially reacting with the material comprising the probing feature.
• the improved method for removing deposits from these features is non-destructive and removes the deposits which build up between probe card features.
• FIG. 7 illustrates a process flowchart for probing an integrated circuit device in one embodiment of the present invention.
• probing features 22 of probe card 20 contact solder bumps 26 on integrated circuit device 28 during a wafer sort, as indicated in block 100.
• solder deposits 29 adhere to probing features 22 of probe card 20.
• probing features 22 disengage the integrated circuit device 28, as indicated in block 110.
• Probing features 22 are next exposed to a composition or solution (block 120) which chemically reacts with solder deposits 29 which substantially or completely removes solder deposits 29 from probing features 22 without substantially reacting with the material comprising probing features 22.
• the probing feature 22 is typically made of a metal or metal alloy, for example, a nickel alloy, and the solder bump is typically made of primarily lead with some tin.
• solder deposits comprised of lead (Pb), lead oxides (PbO), or lead alloys accumulate on the probing feature of the probe card. Stray particle and solder buildup contributes to high contact resistance between the probing feature and the solder bump which in turn causes inaccurate voltage levels during device testing. Moreover, the accumulated buildup of solder may bridge the small gap between probing features resulting in shorts or leakage currents, again leading to unnecessarily lower test yields.
• the present invention includes a process in which the probe features are cleaned by exposing the features to a composition comprised of acetic acid (CH 3 COOH) and hydrogen peroxide (H 2 O 2 ).
• the cleaning solution may also include deionized water (H 2 O).
• the deionized water provides a clean source of water that may be used to dilute the composition. This facilitates the ultimate disposal of the solution.
• a composition consisting of acetic acid (CH 3 COOH), hydrogen peroxide (H 2 O 2 ) and deionized water (H 2 O), in an approximately 1:1:1 volume ratio, is used to remove the solder deposits without significantly affecting the probe features.
• the manner of exposing the probing features to the composition may be accomplished in any number of ways.
• the probing features 72 of a probe card 70 extending from multi-layer ceramic space transformer 71 may be submerged in a container 74 of a cleaning composition 76 comprising acetic acid, hydrogen peroxide and DI water; or
• probing features 72 of probe card 70 may be sprayed with composition 73 comprising acetic acid, hydrogen peroxide, and DI water through a nozzle 75.
• FIG. 9 illustrates a process flowchart for probing an integrated circuit in another embodiment of the present invention.
• probing features 22 of probe card 20 contact solder bumps 26 on an integrated circuit device 28 during a wafer sort, as indicated in block 200.
• solder deposits 29 adhere to probing features 22 of probe card 20.
• probing features 22 disengage the integrated circuit device 28, as indicated in block 210.
• the probing features are scrubbed on an abrasive surface which removes the lead-tin material from the tips of the probing feature, as indicated in block 220.
• the probing feature reengages (block 230) at least one die for testing and disengages (block 240) the die following testing.
• the number of dies tested prior to chemical cleaning typically ranges between approximately 10,000 to 25,000. This range and the number of die tested prior to a chemical cleaning may vary if (i) certain patterns of electrical failures are detected on a number of die in a row, or (ii) dirty probing features are not scrubbed within an hour or two of testing.
• the probing features are exposed to a composition or solution which chemically reacts with the solder deposits (block 250) which substantially or completely removes the solder deposits from the probing feature without substantially reacting with the material comprising the probing feature.
• the cleaning composition comprises hydrogen peroxide, deionized water and acetic acid.
• the composition chemically reacts with the deposits, removing the deposits from the probing feature of the probe card which is substantially accomplished by the reactions: (i) lead and hydrogen peroxide react to form lead oxide and water; and (ii) lead oxide, deionized water, and acetic acid react to form lead acetate and water.
• the material comprising the probing feature typically a nickel alloy, does not substantially react with the cleaning composition.
• solder deposits are removed from both (i) the tips, and (ii) the length of the probing features.
• exposing the probing feature to the cleaning solution (i) inhibits solder from bridging the gaps between probing features; and (ii) facilitates the cleaning of buckling beam type probing features.
• the probing feature may be dried in a variety of ways including merely exposing them to the atmosphere or blowing air, clean air, or nitrogen over the probing feature.
• the probing features comprised of a nickel alloy
• a cleaning composition comprised of hydrogen peroxide, acetic acid, and deionized water in a 1:1:1 volume ratio which substantially or completely removes the solder deposits from the probing features without substantially reacting with the nickel alloy.
• the probing features are sprayed with the cleaning composition for two 45 second periods, each cleaning period utilizing a fresh cleaning composition.
• the probing features are then rinsed with deionized water. Clean air is then blown over the probing features to accelerate the drying process. Following drying, the probe card resumes testing die in a wafer sort.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Measuring Leads Or Probes (AREA)
• Testing Or Measuring Of Semiconductors Or The Like (AREA)
• Tests Of Electronic Circuits (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=21700971

Family Applications (1)

Country Status (5)

Cited By (25)

Families Citing this family (20)

Family Cites Families (13)

• 1998
  • 1998-01-02 US US09/002,479 patent/US6121058A/en not_active Expired - Lifetime
  • 1998-12-21 JP JP2000527836A patent/JP2002501177A/ja active Pending
  • 1998-12-21 WO PCT/US1998/027393 patent/WO1999035505A2/en not_active Ceased
  • 1998-12-21 AU AU20920/99A patent/AU2092099A/en not_active Abandoned
  • 1998-12-21 KR KR10-2000-7007395A patent/KR100367112B1/ko not_active Expired - Fee Related

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