Patent Application
20200049762
The present application is based on and claims priority from Japanese Patent Application No. 2018-148735, filed on Aug. 7, 2018, with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.
The present disclosure relates to a technology of inspecting a probe that performs an electrical measurement of an integrated circuit (IC).
In a process of manufacturing a semiconductor device, a probe test is performed after ICs are formed on the surface of a semiconductor wafer (hereinafter, referred to as a “wafer”), to measure an electrical characteristic of each IC in a state where the IC chip is not separated from the wafer (in this case, the wafer corresponds to an inspection target substrate) or in a state where the separated IC chip is placed in a dedicated inspection target substrate.
The probe test is performed using, for example, a probe card provided with a number of probes, and carried out by firmly pressing the inspection target substrate against the probe card such that an electrode pad of an IC to be inspected is brought into contact with the probes, and inputting/outputting inspection electric signals.
In the probe test described above, in order to accurately contact an electrode pad of each IC in the inspection target substrate with the probes of the probe card, it is necessary to accurately grasp the position of the electrode pad of each IC and the positions of the probes of the probe card, and perform an alignment for aligning the positions of the electrode pad and the probes.
In order to perform the alignment, as a method of grasping the positions of the respective probes of the probe card, there is a known method of firmly pressing the probe card against a needle mark transfer sheet (a needle mark transfer member) made of a resin and deforming the portions of the resin that are brought into contact with the probes so as to transfer needle marks. By, for example, capturing an image of the needle mark transfer sheet to which the needle marks have been transferred, information of the arrangement position of the probes or the like may be acquired.
For example, Japanese Patent Laid-open Publication No. 2011-049261 (Claim 1 and paragraph [0040]) describes a technology of transferring needle marks by bringing the probes into contact with a monofunctional (meth) acrylate.
An embodiment of the present disclosure provides a probe apparatus for performing an electrical measurement by bringing a probe provided on a probe card into contact with a substrate placed on a placement table, the probe apparatus including: a transfer table provided with a needle mark transfer member to which a needle mark of the probe is transferred and configured to bring the probe into contact with the needle mark transfer member, instead of bringing the probe into contact with the substrate; and a mover configured to move an arrangement position of at least one of the transfer table and the probe card between a contact position where the needle mark transfer member is brought into contact with the probe and a separation position where the needle mark transfer member is separated from the contact position, the needle mark transfer member including a polyimide resin
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made without departing from the spirit or scope of the subject matter presented here.
First, an entire configuration of a probe apparatus according to an embodiment will be described with reference to
As illustrated in
For example, the Y stage 21 or the X stage 22 is provided with a ball screw or a linear motor mechanism (not illustrated), and the stop position of the Y stage 21 in the Y direction and the stop position of the X stage 22 in the X direction may be accurately adjusted using a motor with which an encoder or a linear scale is combined.
A Z movement unit 23 is provided on the X stage 22 to be supported by a telescopic shaft 231 configured to be telescopic, and is configured to be movable up and down in the Z direction (the vertical direction). Further, a wafer chuck 2 is provided on the side of the upper surface of the Z movement unit 23 and configured to be rotatable about the Z axis on the Z movement unit 23 (movable in the θ direction). The movement amount in the Z direction and the rotation amount of the wafer chuck 2 may also be accurately grasped by an encoder.
The above-described Y stage 21, X stage 22, and Z movement unit 23 constitute a wafer movement mechanism, and may move the wafer chuck 2 in each of the X, Y, Z, and θ directions.
The upper surface of the wafer chuck 2 serves as a placement surface for placing a wafer with inspection target ICs thereon, and holds the wafer by an adsorption. The wafer chuck 2 corresponds to a placement table of the present embodiment.
When an area where the wafer chuck 2 (the wafer placed on the placement surface) moves by the action of the Y stage 21, the X stage 22, and the Z movement unit 23 is referred to as a movement area, a probe card 3 is provided above the movement area. The probe card 3 is detachably mounted in a head plate 12 which is a top plate of the housing body 1.
The probe card 3 is configured as a printed circuit board (PCB), and a group of electrodes (not illustrated) is formed on the upper surface of the probe card 3. Further, an intermediate ring 41 is interposed between a test head 4 disposed above the head plate 12 and the probe card 3, to establish an electric conduction between terminals of the test head 4 and the group of electrodes described above.
The intermediate ring 41 is configured as a pogo pin unit provided with a number of pogo pins 411 which serve as electrode portions, to correspond to the arrangement position of the group of electrodes of the probe card 3. For example, the intermediate ring 41 is fixed to the side of the test head 4.
In addition, the test head 4 is configured to be rotatable around the horizontal rotation axis by a hinge mechanism (not illustrated) provided beside the housing body 1. With this configuration, the test head 4 may be rotatably movable between a measurement position where the test head 4 holds the intermediate ring 41 horizontally to bring the respective pogo pins 411 into a state being in contact with the group of electrodes of the probe card 3 (
In addition, the test head 4 includes a data storage (not illustrated) that stores, as inspection data, an electric signal indicating an electric characteristic of an IC which is measured via the probe card 3, and a determination unit (not illustrated) that determines a presence/absence of an electrical defect in the inspection target IC based on the inspection data.
A number of probes 31 are provided on the lower surface of the probe card 3 to be electrically connected to the group of electrodes, respectively, on the upper surface of the probe card 3.
In addition, as represented in experiment results of Examples to be described later, the probe 31 may be configured by, for example, a vertical needle that extends vertically downward from the lower surface of the probe card 3, a pogo pin of which tip is capable of projecting from/retracting into the pin body, or a cobra pin provided with a curved portion in the middle of the pin body such that the tip of the pin is movable up and down when the pin is brought into contact with an electrode pad of an IC.
The probe apparatus having the configuration described above grasps the arrangement position of each probe 31 using a transfer mechanism 5 and an image capturing unit 6, in performing the alignment work described above.
Hereinafter, a configuration of the transfer mechanism 5 will be described with reference to
As illustrated in
The support arm 232 is provided on the upper end of the telescopic shaft 231 together with the Z movement unit 23 described above, and is movable in the Y, X, and Z directions by the action of the Y stage 21, X stage 22, and the telescopic shaft 231. The Y stage 21, the X stage 22, and the telescopic shaft 231 function as a movement mechanism that moves the needle mark transfer sheet 51 (the transfer mechanism 5).
A Peltier element 521 is disposed inside the transfer table 52. The Peltier element 521 may switch the surface thereof in contact with the transfer table 52 to a heating surface or a cooling surface.
When the surface in contact with the transfer table 52 is set as the heating surface, and the needle mark transfer sheet 51 placed on the transfer table 52 is heated to a preset temperature, the transfer table 52 functions as a heater. In addition, when the surface in contact with the transfer table 52 is set as the cooling surface, and the needle mark transfer sheet 51 placed on the transfer table 52 is cooled to a preset temperature, the transfer table 52 functions as a cooler.
The heating temperature and the cooling temperature of the needle mark transfer sheet 51 will be described later with descriptions of a material of the needle mark transfer sheet 51.
A fan housing 531 is provided between the needle mark transfer sheet 51 and a fan 53, and has a frame body structure that houses the fan (cooling unit) 53. The fan 53 has a function to cool the heat radiation surface of the Peltier element 521 of which the surface in contact with the transfer table 52 is set as the cooling surface, or a function of a cooler to cool the body of the transfer table 52 heated by the Peltier element 521.
The needle mark transfer sheet 51 is a member that is placed on the upper surface of the transfer table 52 and made of a flat sheet-shaped polyimide resin with a thickness of about several hundred micrometers to several millimeters. When the needle mark transfer sheet 51 has a structure in which multiple types of resins are laminated, at least the upper surface of the needle mark transfer sheet 51 which is brought into contact with the probes 31 is made of a polyimide resin. The needle mark transfer sheet 51 placed on the transfer table 52 has the area with which the tips of all the probes 31 provided on the probe card 3 may be contacted.
The transfer table 52 holds the needle mark transfer sheet 51 at a height position where the upper surface of the wafer placed on the wafer chuck 2 and the upper surface of the needle mark transfer sheet 51 have the same height.
As for the polyimide resin used for the needle mark transfer sheet 51, a known polyimide resin of related art (e.g., a polyimide resin obtained by adding a plasticizer to a solvent-soluble polyimide resin and processing the polyimide resin to be in a sheet form) may be used.
Appropriately, when the temperature of the wafer at the time of measuring an electrical characteristic of an IC is TS [° C.], it is preferable to select a polyimide resin of which a peak temperature TP at which a temperature characteristic of a loss tangent (hereinafter, also referred to as “tan δ”) peaks (becomes maximum) falls within a range of TS±10° C.
Here, tan δ[−] is a ratio of a loss elastic modulus E″ [Pa] of a sample to a storage elastic modulus E′ [Pa] which are measured using a known dynamic viscoelasticity measuring device, and is obtained by the following Equation (1).
tan δ=E″/E′ (1)
As illustrated in
Accordingly, the polyimide resin is hard in the low temperature region (the storage elastic modulus E′ is high), so that it is difficult to transfer needle marks by the contact with the probes 31. However, once needle marks are formed, a state where the indentation is formed may be maintained. Meanwhile, while the polyimide resin is soft (the storage elastic modulus E is low) in the high temperature region so that needle marks are easily formed by the contact with the probes 31, the formed needle marks may easily disappear in a short time.
In other words, when the temperature is excessively low, it is difficult to transfer needle marks to the polyimide resin even by bringing the probes 31 into contact with the polyimide resin, and when the temperature is excessively high, transferred needle marks immediately disappear, and thus, the needle marks may not be maintained until a timing for performing a position detection to be described later.
With regard to the polyimide resin having the characteristic described above, the inventors of the present disclosure have paid attention to the value of the tan δ described above, and devised a technique of controlling a temperature and transferring and maintaining needles marks.
That is, in a region where the tan δ (=E″/E′)>1.0, more preferably, in a region where the tan δ≥1.5, the influence of the loss elastic modulus E is large, and it is easy to transfer needle marks. Further, it has been found through experiments that in the region described above, transferred needle marks are easily maintained, and an appropriate thermo-plasticity is obtained, only by slightly lowering the temperature of the polyimide resin.
Accordingly, by adopting the polyimide resin having the peak temperature TP of the tan δ that falls within the range of ±10° C. of the temperature TS of the wafer at the time of measuring an electrical characteristic of an IC, needle marks may be transferred and maintained under the substantially same temperature condition as that at the time of using the probes 31.
Here, in the epoxy resin that has been actually used as a material of the needle mark transfer sheet of the related art, it is difficult to transfer needle marks of the probes 31 unless the temperature of the needle mark transfer sheet is raised to around 100° C.
Meanwhile, an electrical characteristic of an IC may be measured under a temperature condition selected from a wide temperature range from sub-zero to 100° C. or more. Thus, for example, when an electrical characteristic is measured at around the room temperature of 15° C. to 35° C., the temperature condition at the time of using the probes 31 and the temperature condition at the time of transferring needle marks may become largely different from each other which causes a thermal expansion of the probes 31, etc., and thus, it may become difficult to accurately grasp the positions of the probes 31.
Meanwhile, in the polyimide resin illustrated in
In addition, the peak temperature TP of the tan δ may be adjusted by adding a plasticizer to the polyimide resin.
According to
As described above, when the peak temperature of the tan δ of the polyimide resin to which the plasticizer is not added is higher than the temperature TS of the wafer at the time of measuring an electrical characteristic of an IC, the addition amount of the plasticizer may be adjusted, so as to adjust the peak temperature TP of the tan δ of the polyimide resin used for the needle mark transfer sheet 51 to fall within the range of TS±10° C.
Despite of a change depending on the peak temperature of the tan δ when no plasticizer is added or the maximum addible amount of the plasticizer, it may be said that the polyimide resin is a material suitable for transferring needle marks of the probes 31 when the wafer temperature TS at the time of measuring an electrical characteristic of an IC falls within the range of 15° C. to 35° C.
Here, the plasticizer which is added to the polyimide resin so as to adjust the peak temperature TP of the tan δ is not limited to the example of the phosphazene derivative, and any modifier may be used as long as the modifier may exhibit the action to change the peak temperature TP.
When the polyimide resin that constitutes the needle mark transfer sheet 51 is selected based on the idea described above, a temperature for bringing the probes 31 into contact with the needle mark transfer sheet 51 to transfer needle marks (transfer temperature) and a temperature for maintaining the transferred needle marks (maintenance temperature) are determined.
In the example illustrated in
The Peltier element 521 provided in the transfer table 52 performs a heating such that the temperature of the needle mark transfer sheet 51 placed on the transfer table 52 becomes the transfer temperature t described above, and performs a cooling such that the temperature of the needle mark transfer sheet 51 after the transfer of needle marks becomes the maintenance temperature
In this way, by setting the transfer temperature t and the maintenance temperature t′ such that the peak temperature of the tan δ falls between the temperatures t and the temperatures t and t′ may be set to be separated from each other as possible in the region where the value of the tan δ is relatively high (e.g., the region where the value of the tan δ is larger than 1.0). As a result, needle marks may be transferred at the temperature t at which the polyimide resin is more easily deformed, and a state where needle marks are formed on the needle mark transfer sheet 51 may be maintained by slightly adjusting the temperature (cooling), as compared with a case where a cooling is performed to a temperature region where the storage elastic modulus E′ becomes flat.
Further, the probe apparatus of the present embodiment includes an image capturing unit 6 that captures images of needle marks transferred to the needle mark transfer sheet 51 and an electrode pad of an IC formed on the wafer placed on the wafer chuck 2.
For example, the image capturing unit 6 includes a charge-coupled device (CCD) camera 61, a main body 62 of the CCD camera 61, two traveling rails 63 that are disposed to extend in parallel with each other in the lateral direction along the opposing inner wall surfaces of the housing body 1, and a support rod 64 that supports the CCD camera 61 in a state of being stretched between the two traveling rails 63 and is connected to a slider (not illustrated) traveling on the traveling rails 63.
The CCD camera 61 is movable in the lateral direction between an image capturing position where the CCD camera 61 enters the lower side of the probes 31 (see
When the CCD camera 61 enters the image capturing position, and the needle mark transfer sheet 51 is positioned below the CCD camera 61, an image of the needle marks transferred to the needle mark transfer sheet 51 is captured. In addition, when the wafer is positioned below the CCD camera 61 positioned at the image capturing position, an image of an electrode pad of an IC is captured.
The probe apparatus having the configuration described above is provided with a controller 7. The controller 7 includes a program, a memory, a data processor including a CPU, etc., and the program is organized with a group of steps for performing an operation to transfer needle marks of the probes 31 to the needle mark transfer sheet 51, an operation to capture an image of the needle marks transferred to the needle mark transfer sheet 51 or an electrode pad of an IC formed on the wafer, and an operation to inspect the wafer after performing the alignment according to the positions of the probes 31 or the electrode pad which are obtained from the image capturing result, by transmitting control signals from the controller 7 to each unit of the probe apparatus. This program is stored in a storage (not illustrated) such as a computer storage medium, for example, a flexible disk, a compact disk, a magneto-optical disk (MO) or the like, and installed in the controller 7.
In addition, the above-described data storage and determination unit which are provided in the test head 4 also constitute a portion of the controller 7.
Hereinafter, an operation to inspect the probes 31 by the probe apparatus of the present embodiment will be described with reference to
First, a probe detection mechanism (not illustrated) is moved to the lower side of the probes 31 using the movement mechanism (the Y stage 21 and the X stage 22). Then, the probe detection mechanism is lifted by the telescopic shaft 231 to detect the height position of the probes 31.
After the height position of the tips of the probes 31 is detected, the Peltier element 521 heats the needle mark transfer sheet 51 to the transfer temperature t (30° C. in the example of the polyimide resin illustrated in
When the needle mark transfer sheet 51 has a thickness of about several hundred micrometers, the heat capacity of the needle mark transfer sheet 51 is sufficiently small, and the heat transfer rate thereof is also sufficiently fast. Thus, the temperature control may be performed by regarding the measurement result of the temperature of the transfer table 52 as the temperature of the needle mark transfer sheet 51.
When the needle mark transfer sheet 51 is heated to the transfer temperature, the needle mark transfer sheet 51 is lifted to the height position at which the transfer of needle marks is performed (a contact position: the height position at which the upper surface of the wafer placed on the wafer chuck 2 and the upper surface of the needle mark transfer sheet 51 are the same) to bring each probe 31 into contact with the needle mark transfer sheet 51 (
By suppressing the difference between the transfer temperature t and the maintenance temperature t′ to be within, for example, 10° C., a rapid temperature adjustment becomes possible, and a state where clear needle marks are transferred to the surface of the needle mark transfer sheet 51 may be maintained. In addition, the cooling of the needle mark transfer sheet 51 may be started before the lowering of the needle mark transfer sheet 51 is started.
Next, the CCD camera 61 enters the image capturing position to capture an image of the needle marks transferred to the needle mark transfer sheet 51 (
Based on the image data obtained by each image capturing, a defect, a damage or the like of the probes 31 is detected from the shapes of the needle marks in the image data. Further, the arrangement position of the tip of each probe 31 is detected from each position where a needle mark is formed within the needle mark transfer sheet 51.
Meanwhile, when there is a defect⋅damage, a positional deviation or the like of the probes 31, alarm information or the like is output to a monitor screen to notify an operator of the occurrence of the event.
When no defect⋅damage or positional deviation of the probes 31 is detected, the wafer is carried into the housing body 1 to become a state where the inspection of an IC may be started.
Meanwhile, the needle mark transfer sheet 51 that has been subjected to the image capturing is heated to a temperature sufficiently higher than the transfer temperature, for example, 70° C., so as to erase the needle marks transferred to the needle mark transfer sheet 51. Then, the needle mark transfer sheet 51 stands by in a state of being cooled to, for example, the room temperature using the Peltier element 521 and the fan 53.
When the inspection of the probes 31 is ended in this way such that the inspection of the wafer may be performed, the wafer is carried into the housing body 1 by an external conveyance arm (not illustrated), and placed on the wafer chuck 2. Then, the image capturing unit 6 described above enters the image capturing position to capture an image of an electrode pad of each IC and detect the position thereof.
Then, based on the arrangement position of the probes 31 that is acquired in advance based on the result of the transfer of needle marks to the needle mark transfer sheet 51 and the result of the detection of the position where the electrode pad of each IC formed on the carried-in wafer is formed, the alignment of the wafer chuck 2 in the X, Y, and 0 directions is performed so as to cause the probes 31 to be accurately contacted with the electrode pads. Then, the wafer chuck 2 is lifted by the telescopic shaft 231, the aligned wafer is pressed against the probe card 3, and the electrode pad of a predetermined IC is brought into contact with the probes 31, so as to measure the electrical characteristic.
Then, the wafer chuck 2 (wafer) is sequentially moved with respect to the probe card 3 using the movement mechanism, and the same operation as described above is repeated on the electrode pad of each of the multiple ICs formed on the wafer to perform the inspection.
When the inspection of all of the ICs on the wafer is ended in this way, the wafer chuck 2 is moved to the initial position, the inspected wafer is carried out by an external conveyance arm, and the next wafer is placed on the wafer chuck 2. The inspection of the probes 31 using the needle mark transfer sheet 51 may be performed before the carry-in of each wafer or may be performed each time a preset number of wafers are inspected.
The probe apparatus according to the present embodiment has the following effect. Since the needle mark transfer sheet 51 to which needle marks are transferred by the contact with the probes 31 is made of the polyimide resin, clear needle marks may be transferred.
Here, in the example described above with reference to
In addition, it may not be necessarily performed to adjust the peak temperature of the polyimide resin to be within the range of TS±10° C. (where Ts is the temperature of the wafer at the time of measuring an electrical characteristic of an IC) by using the plasticizer. When the positions of the probes 31 may be accurately detected even though the difference between TS and the temperature of the needle mark transfer sheet 51 is large, the needle mark transfer sheet 51 may be constituted by the polyimide resin in which the difference between TS and the peak temperature of the tan δ is 10° C. or higher.
In addition, the heating and the cooling of the needle mark transfer sheet 51 may not be necessarily performed, and when needle marks of the probes 31 may be transferred and maintained at the atmospheric temperature inside the housing body 1 of the probe apparatus, the heater and the cooler such as the Peltier element 521 and the fan 53 may not be provided.
In addition, in the probe apparatus illustrated in
In addition, an IC which is subjected to the measurement of an electrical characteristic using the probe apparatus of the present embodiment is not limited to an IC formed on the wafer, and may be an IC which is separated from the wafer, packaged, and mounted on a dedicated inspection target substrate.
(Experiment)
The needle mark transfer sheet 51 made of the polyimide resin and the needle mark transfer sheet 51 made of the epoxy resin were brought into contact with the probes 31, and the difference in transfer of needle marks was examined
A. Experimental Conditions
The needle mark transfer sheet 51 made of the polyimide resin having the characteristic illustrated in
The same experiment as that of Example 1 was conducted, except that each probe 31 formed by a vertical needle with a square planar tip was brought into contact with the needle mark transfer sheet 51. The diameter of the needle tip of the probe 31 was 5 μm, and four O.D. amounts of 20 μm, 30 μm, 40 μm, and 50 μm were performed.
The same experiment as that of Example 1 was conducted, except that each probe 31 formed by a crown-shaped pogo pin with four tips were brought into contact with the needle mark transfer sheet 51. The diameter of the needle tip of the probe 31 was 80 μm, and the O.D. amount was 40 μm.
The same experiment as that of Example 1 was conducted, except that each probe 31 formed by a cobra pin provided with a curved portion in the middle of the pin body was brought into contact with the needle mark transfer sheet 51. The diameter of the needle tip of the probe 31 was 80 μm, and the O.D. amount was 80 μm.
The needle mark transfer sheet 51 mainly made of the epoxy resin having the temperature characteristics of the storage elastic modulus E′ and the tan δ illustrated in
The same experiment as that of Comparative Example 1 was conducted, except that the same probes 31 as those of Example 2 were used (but three O.D. amounts of 50 μm, 60 μm, and 70 μm were performed).
The same experiment as that of Comparative Example 1 was conducted, except that the same probes 31 as those of Example 3 were used.
The same experiment as that of Comparative Example 1 was conducted, except that the same probes 31 as those of Example 4 were used.
B. Experiment Results
According to the experiment results represented in
The needle marks in the Comparative Examples (Comparative Examples 1 to 3:
According to the results of the transfer of needle marks to the needle mark transfer sheet 51 in Examples 1 to 4 and Comparative Examples 1 to 4 described above, it may be said that the technique of transferring the needle marks of the probes 31 using the needle mark transfer sheet 51 made of the polyimide resin is suitable for the inspection of the probes 31 using image data.
According to the present disclosure, since the needle mark transfer member to which needle marks are to be transferred by a contact with the probes includes the polyimide resin, clear needle marks may be transferred.
From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-148735 | Aug 2018 | JP | national |
