JP2022144843A - Chip strength test method - Google Patents

Abstract

To provide a new test method capable of measuring and evaluating the strengths of semiconductor device chips, etc. being buried by resin encapsulation or buried in a card.SOLUTION: A test method includes: a preparation step of preparing a package substrate having an encapsulation resin layer encapsulating a chip disposed on a base substrate; a thinning step of thinning the encapsulation resin layer to expose the chip; a tape bonding step of bonding a protective tape onto the package substrate; a pressing step of supporting a lower surface of the package substrate at a side of the base substrate by a pair of support rollers each having a rotational axis extending in a first direction, and pressing an upper surface of the protective tape by a prescribed force by a pressing roller having a rotational axis extending in the first direction; a reciprocating step of starting to continuously reciprocate in a second direction orthogonal to the pressing roller; and a chip breakage detection step of detecting breakage of a chip after the reciprocating step is performed.SELECTED DRAWING: Figure 2

Description

The present invention relates to a chip strength test method for resin-sealed chips.

Conventionally, semiconductor device chips are manufactured by thinning and singulating a semiconductor wafer. In recent years, as shown in FIG. 10, semiconductor device chips manufactured in this manner are widely used by embedding them in cards such as ID cards, credit cards, transportation IC cards, and the like. ing.

Semiconductor device chips are also used in electronic equipment as packaged chip packages. As a manufacturing process of a chip package, for example, after arranging a plurality of semiconductor device chips on a substrate, they are sealed with a sealing resin to form a package substrate, and this package substrate is diced to obtain a plurality of chips. It is known to be packaged.

By the way, when a large impact is applied to a semiconductor device chip, damage such as cracks or cracks may occur and the function of the device may be lost. Chips with low bending strength are particularly susceptible to damage.

The bending strength of a chip varies depending on the material and thickness of the chip, as well as the processing conditions when thinning and singulating the semiconductor wafer. The chip is evaluated and various processing conditions are selected, and a testing device for measuring the bending strength of the chip is also well known (see Patent Document 1, for example).

JP 2020-190449 A

As disclosed in Patent Document 1, the conventional testing apparatus measures the bending strength of the semiconductor device chip itself, and there is no apparatus for measuring the bending strength of the chip package after packaging. rice field.

In addition, as the demand for miniaturization of electronic devices continues to increase, it is widely practiced to reduce the thickness by grinding the package substrate to a thickness that exposes the semiconductor device chip resin-sealed on the package substrate. Further, it is strongly desired to measure and evaluate the strength of the semiconductor device chip in the state of being thinned while being resin-encapsulated.

Moreover, it is strongly desired to be able to measure and evaluate the strength of the chips embedded in the various cards described above.

In view of the above problems, the present invention provides a novel test method capable of measuring and evaluating the strength of a semiconductor device chip embedded by resin encapsulation or a semiconductor device chip embedded in a card. It is.

The problems to be solved by the present invention are as described above, and the means for solving the problems will now be described.

According to one aspect of the invention,
A chip strength test method comprising:
a preparation step of preparing a package substrate having a base substrate, a chip arranged on the base substrate, and a sealing resin layer for sealing the chip;
a thinning step of thinning the sealing resin layer of the package substrate to expose the chip;
a tape applying step of applying protective tape to the package substrate to cover the exposed chip after performing the thinning step;
A pair of support rollers each having a rotation shaft extending in a first direction supports the lower surface of the package substrate on the side of the base substrate, and is disposed between the pair of support rollers and extends in the first direction. a pressing step of pressing the upper surface of the protective tape with a predetermined force with a pressing roller having a rotating shaft;
a reciprocating step of starting to reciprocate continuously the package substrate supported by the pair of support rollers and pressed by the pressure rollers in a second direction intersecting the pressure rollers;
and a chip breakage detection step of detecting breakage of the chip after the reciprocating step is performed.

Further, according to one aspect of the present invention,
further comprising a data storage step of storing the time and/or the number of reciprocating movements required from the reciprocating step starting the reciprocating movement until the chip breakage detecting step detects breakage of the chip. and

According to the present invention, it is possible to measure the chip strength of a test piece obtained by preparing and thinning a package substrate, and to evaluate processing conditions during thinning. Furthermore, by attaching a protective tape to the surface of the chip, it is possible to prevent scattering of fragments when the chip is broken, and to prevent dust generated when the chip is broken from adhering to a roller or the like. As a result, it is possible to prevent debris from broken chips from adhering to the pressing roller or the like, adversely affecting the test, and making accurate evaluation impossible.

Moreover, by appropriately selecting the material and thickness of the protective tape, it is possible to construct a state in which the chip is artificially embedded in the card, and the strength of the chip embedded in the card can be evaluated.

(A) is a perspective view of a package substrate serving as a test piece. (B) is a side sectional view of the same. (C) is a side cross-sectional view of the package substrate thinned by back grinding. (D) is a side cross-sectional view of the package substrate to which the protective tape is attached. The figure which shows one Embodiment of the testing apparatus of chip|tip strength. (A) is a diagram showing a test piece moving unit and the like. (B) is a diagram showing a test piece moving unit and the like in which the test piece is held. The figure explaining the structure of a press unit. The flowchart explaining the procedure of a test method. The figure explaining the example which thins a test piece by grinding. (A) is a diagram showing a state in which a pressing unit presses a test piece. (B) is a diagram for explaining a state in which the test piece is moved. (A) is a partial enlarged view of a pressed portion in FIG. 7(A). (B) is a partially enlarged view of a pressed portion in FIG. 7(B). (A) is a top view of the test piece before the start of pressing. (B) is a diagram showing a state in which some chips are broken by one movement. (C) is a diagram showing a state in which another chip is broken by two movements. FIG. 4 is a diagram showing an example of a card with embedded chips.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1(A) is a perspective view of a package substrate to be a test piece, FIG. 1(B) is a side cross-sectional view of the same, and FIG. 1(C) is a side cross-section of the package substrate thinned by back grinding. FIG. 1D is a side cross-sectional view of a package substrate to which a protective tape is adhered.

As shown in FIGS. 1A and 1B, a plurality of semiconductor device chips 10 (hereinafter also simply referred to as "chips 10") are manufactured by dicing a wafer, and are made of resin or metal. After being fixed on the base substrate 12 with a predetermined interval via a die attach material or the like, a sealing resin layer 14 is formed by sealing with a mold resin, and the plate-shaped package substrate 1 (strip substrate) is configured. be.

For the plurality of chips 10, for example, chips picked up from a plurality of locations on one wafer whose back surface has been ground can be used. In this case, it is possible to evaluate the bending strength of chips at different positions on the same wafer, and it is possible to evaluate the machining accuracy of the backside grinding and the like based on this bending strength.

Also, the plurality of chips 10 can be prepared by preparing a plurality of wafers thinned by changing the conditions of backside grinding, and picking up from the same portion of each wafer. In this case, it is possible to evaluate the bending strength of the chips at the same position on each wafer, and it is possible to evaluate the back grinding conditions and the like based on this bending strength.

FIG. 1C shows the package substrate 1 in which the sealing resin layer 14 of the package substrate 1 is thinned by grinding and the chip 10 is exposed.

FIG. 1(D) shows a test piece obtained by attaching a protective tape 16 to the exposed surface of the chip 10 side of the thinned package substrate 1 . The protective tape 16 can be composed of, for example, a resin film having a base material and a glue layer laminated on the base material, and is adhered to the sealing resin layer 14 . A test piece constructed in this manner is set in a test apparatus, and the bending strength and the like of each chip 10 are measured and evaluated.

Moreover, the test piece may have a configuration in which a plurality of chips are arranged on a substrate at predetermined intervals, or a configuration in which only one chip is provided on the substrate.

Next, a configuration example of a chip strength testing apparatus will be described.
FIG. 2 is one embodiment of a chip strength testing apparatus 20 . The test apparatus 20 mainly includes a test strip moving unit 30, a pressing unit 40, and a chip breakage detection unit 50. As shown in FIG.

As shown in FIG. 2 and FIGS. 3A and 3B, the test piece moving unit 30 is installed on the base 22 of the test device 20, and clamps the package substrate 1, which is the test piece, to the second moving unit. direction (X-axis direction).

The test strip moving unit 30 includes a moving base 32 and a support mechanism 34 that sandwiches and supports the package substrate 1 between the moving base 32 and the moving base 32 .

The movable base 32 is slidably mounted on a pair of guide rails 36 extending in the second direction and installed on the upper surface of the base 22, and a ball screw 38 arranged between the guide rails 36 on the back side. screwed together. By rotating the ball screw 38 with the pulse motor 39, the movable base 32 moves in the second direction (X-axis direction).

The support mechanism 34 has a flange 35a arranged with a gap formed between the movable bases 32, and a flange lifting mechanism 35b. By moving the flange 35a up and down by the flange vertical movement mechanism 35b, the package substrate 1 can be sandwiched by narrowing the gap with the movable base 32, or the package substrate 1 can be held by widening the gap with the movable base 32. can be released.

As shown in FIGS. 2 and 4, the pressing unit 40 includes a pair of support rollers 41 that support the package substrate 1 from below, a pressing roller 42 that presses the package substrate 1 from above, and a pressing roller 42. and a pressing roller moving unit 43 that moves up and down between the pressing position and the retracted position.

As shown in FIG. 2 , a gate-shaped frame 23 is erected on the base 22 , and a pressing roller moving unit 43 is arranged on the side surface of the beam portion of the frame 23 .

As shown in FIG. 4, the pressing roller moving unit 43 includes a body portion 43a and a moving portion 43b that moves vertically with respect to the body portion 43a. The body portion 43a is configured by, for example, an air actuator, and configured to move the moving portion 43b up and down by air pressure. The body portion 43a is provided with a load cell (not shown) for monitoring the load received from the moving portion 43b. By referring to the detected value of the load cell, the main body portion 43a can maintain the load acting downward on the moving portion 43b at a predetermined value. can be pressed with It should be noted that, instead of providing a load cell, a configuration may be adopted in which the air pressure is adjusted by a valve that supplies air to the air actuator so as to press with a predetermined force.

As shown in FIG. 4, a long plate-shaped bracket 43c is provided at the lower end of the moving portion 43b, and a pressure roller 42 and a plurality of support rollers 42a for supporting the pressure roller 42 are provided below the bracket 43c. be done. The pressing roller 42 is a long roller extending in the first direction and freely rotating.

As shown in the enlarged portion of FIG. 4, the support rollers 42a are short rollers that are arranged diagonally above and to the left and right of the pressing roller 42, and are alternately displaced from each other in the longitudinal direction of the pressing roller 42. placed. The support roller 42a abuts on the left and right obliquely upper parts of the pressing roller 42 and functions to prevent the elongated pressing roller 42 from bending. In addition, in FIG. 4, only some support rollers 42a are illustrated. 4 is a view viewed in the direction of arrow A. FIG.

As shown in FIG. 4, a base plate portion 44 is provided on the base 22, and a pair of support rollers 41 are provided on the base plate portion 44 so as to be spaced apart by a predetermined distance in the second direction. Each support roller 41 is a long roller extending in the first direction and freely rotating. Both ends of each support roller 41 are supported by bearing portions 44a, and the bearing portions 44a are slidably provided on guide rails 44b extending in the second direction.

As shown in FIG. 4, a plurality of support roller support portions 44c are arranged in the first direction on the base plate portion 44, and each support roller 41a is supported by each support roller support portion 44c. Each support roller 41 a is in contact with the outer side of each support roller 41 (the side away from the pressing roller 42 in the second direction (X-axis direction)) and obliquely below the support roller 41 . It works to prevent it from happening. Moreover, the movement of the support roller 41 in the second direction is restricted within a predetermined range by contacting the support roller 41a.

As shown in the enlarged portion of FIG. 4, the package substrate 1 is inserted between a pair of lower support rollers 41 and an upper pressure roller 42 when the test is performed. Then, as shown in FIG. 2, the front end side of the package substrate 1 passes through the pressing unit 40 and the frame 23 and is supported by the support table 45 provided on the base 22 .

As shown in FIG. 2, the support table 45 is provided in the vicinity of the frame 23 on the base 22 and has a plurality of ball rollers 45a for supporting the lower surface of the package substrate 1. As shown in FIG.

As shown in FIG. 2, the test apparatus 2 has a chip breakage detection unit 50 for detecting a chip breakage state. In this embodiment, a top observation device 51 for observing the package substrate 1, which is a test piece, from above, a side observation device 52 for observing from the side, and chip detection based on information from these observation devices. and a detection device 53 for detecting a state of destruction. It should be noted that the chip breakage detection unit 50 may not be provided, and the operator may visually or audibly confirm the breakage state of the chip. Alternatively, only one of the top observation device 51 and the side observation device 52 may be provided.

The top observation device 51 and the side observation device 52 are, for example, imaging devices such as optical cameras and infrared cameras (IR cameras), sound sensors (microphones) for detecting breaking sounds, eddy current displacement sensors, and the like. Can be configured.

The detection device 53 may be incorporated in the control device 100 of the test device 2 or may be provided as a dedicated device.

Information output from the top observation device 51 and the side observation device 52 is input to the detection device 53 . Specifically, it is captured image data, sound data, and the like.

A load measurement value obtained by a load cell (not shown) provided in the pressing unit 40 may be input to the detection device 53 .

The detection device 53 detects the presence or absence of chip breakage based on the input information. For example, chip destruction can be detected by detecting cracks through image analysis of captured image data, chip destruction can be detected by detecting abnormal sounds in sound data, and eddy current displacement detection can be performed. Breakage of the chip can be detected by detecting changes in the oscillation amplitude of the sensor.

The detection device 53 has a counter for measuring the number of reciprocating movements of the package substrate 1 and the pressing time. The detection device 53 associates and stores the timing of detecting the occurrence of chip destruction, the number of reciprocating movements of the package substrate 1, and the pressing time.

Next, a test method using the test apparatus configured as described above will be described in order of the flow chart shown in FIG.

<Preparation step>
As shown in FIG. 1, the step is to prepare a test piece in which a chip 10 is resin-sealed as shown in FIGS. 1(A) and 1(B). The test piece in the example shown in FIGS. 1A and 1B is a package substrate 1, and includes a base substrate 12, a chip 10 arranged on the base substrate 12, and a sealing resin layer 14 sealing the chip 10. and have

<Thinning step>
As shown in FIG. 1C, this is a step of thinning the sealing resin layer 14 of the package substrate 1 to expose the chip 10 . For example, as shown in FIG. 6, the thinning process is performed by holding the package substrate 1 by suction via a tape 72 on a holding table 71 of a grinding device 70, and by using a grinding wheel 74 having a grinding wheel 73. A method of grinding the sealing resin layer 14 can be used. In addition to grinding using a grinding wheel, cutting using a cutting bit may also be performed.

<Tape sticking step>
After performing the thinning step, as shown in FIG.
By covering the surface of the chip 10 with the protective tape 16 in the package substrate 1 where the chip 10 is exposed in this way, it is possible to prevent the fragments of the chip 10 destroyed in the subsequent pressing step from scattering. It is possible to prevent debris from broken chips from adhering to the pressing roller or the like, adversely affecting the test, and making accurate evaluation impossible.

For example, when the top observation device 51 is a camera, the protective tape 16 is selected from a tape having transparency to light in the wavelength region to which the camera is sensitive, so that the broken state of the chip 10 can be visually recognized and photographed. It becomes possible.

Further, by selecting the material and thickness of the protective tape 16, the overall thickness of the package substrate 1 can be set to, for example, about 0.5 mm to 1.5 mm. As a result, as shown in FIG. 10, it is possible to form a card with a thickness equivalent to that of general cards C such as an ID card, a credit card, and a transportation IC card, thereby simulating the cards C in which the chip 10D is embedded. can be configured As for the cards C, the chip may be exposed, the whole may be laminated and protected with protective tape, or the chip may be arranged on the back side of the electrode surface provided on the surface of the card.

The protective tape 16 may be made of, for example, polyvinyl chloride or glycol-modified polyethylene terephthalate used for IC cards.

<Press step>
As shown in FIG. 7A and FIG. 8A, this is a step of pressing the upper surface of the package substrate 1 with a predetermined force using the pressing roller 42 .

First, as shown in FIG. 7A, the pressure roller moving unit 43 moves the package substrate 1 to align the chip 10 to be tested to a position where it is sandwiched by the pressure unit 40 . This alignment can be performed, for example, by imaging with the top observation device 51 or by visual confirmation.

Next, as shown in FIG. 8A, the moving portion 43b of the pressing unit 40 is lowered, and the pressing roller 42 presses the upper surface of the package substrate 1 with a predetermined force. More specifically, a pair of support rollers 41 each having a rotation shaft extending in the first direction supports the lower surface of the package substrate 1 on the side of the base substrate, and is arranged between the pair of support rollers 41 to A pressing roller 42 having a rotation shaft extending in one direction presses the upper surface of the protective tape 16 with a predetermined force.

At this time, if the chip 10 is broken, the bending strength of the chip 10 may be evaluated based on the measured value detected by the load cell when the chip 10 is broken.

When the package substrate 1 is pressed against the pressure roller 42, the package substrate 1 is covered with the protective tape 16. Therefore, even if the chip 10 is broken by receiving the load from the pressure roller 42, fragments of the chip 10 can be removed. Does not scatter.

As shown in FIG. 8A, during pressing, the pressing roller 42 is supported obliquely from above by a support roller 42a, and the pair of support rollers 41 is supported obliquely from below by a support roller 41a. be done.

<Round-trip movement step>
As shown in FIGS. 7A and 7B and FIGS. 8A and 8B, this is a step of continuously reciprocating the package substrate 1 in the second direction (X-axis direction).

As shown in FIGS. 7A and 7B and FIGS. 8A and 8B, the tip 10 is reciprocated in the second direction (X-axis direction) while the load is applied by the pressing roller 42. A load is intermittently applied to the tip 10, and the tip 10 is broken in the process of repeating the movement. The second direction (X-axis direction) is a direction orthogonal to the first direction (Y-axis direction), which is the axial direction of the pressing roller 42 .

<Chip destruction detection step>
This is the step of detecting breakage of the chip 10 at a predetermined timing after the reciprocating step is performed.

For example, after reciprocating the chip 10 to be inspected once in the reciprocating step, as shown in FIG. The device 51 captures an image of the top surface of the chip 10 and the detection device 53 analyzes the captured image to detect whether or not the chip 10 is broken.

In addition to detecting breakage of the chip itself, breakage of the substrate (base substrate 12 (FIG. 8B)) may also be detected to evaluate the strength of the substrate. In the case where the wiring layer included in the substrate is difficult to destroy, the wiring layer included in the substrate may be imaged with an IR camera, and the strength of the chip and substrate as a whole may be evaluated based on the destruction (damage) of the wiring layer. .

The breakage of the chip 10 can be detected by detecting an abnormal sound in the sound data or by listening to the breakage sound by the operator, and the breakage of the substrate can be detected by detecting a change in the oscillation amplitude of the eddy current sensor. You can also do it by

<Data storage step>
It is a step of storing the time and/or the number of times of reciprocating movement required until the breakage of the chip is detected in the chip breakage detecting step after the reciprocating movement is started in the reciprocating movement step.

In the reciprocating step, the detecting device 53 counts the time when the reciprocating movement is started, stops counting when the breakage of the chip 10 is detected, and stores the time from the start to the stop of the counting.

The detecting device 53 counts the number of reciprocating movements when the reciprocating movement is started in the reciprocating step, stops counting when the breakage of the chip 10 is detected, and counts the number of reciprocating movements from the start of counting until the stop. memorize

The storage of time and the storage of the number of round trips can be both or either one. The detection device 53 stores the time and/or the number of reciprocating movements required for breaking the tip 10 as described above.

The bending strength of the tip 10 can be evaluated using the time required for breaking the tip 10 and/or the number of reciprocating movements stored as described above.

For example, when the time required for chip breakage is short, the bending strength is low, and when the time is long, the bending strength is high. In this way, strength can be evaluated on the basis of time.

For example, when the number of reciprocating movements required for breaking the chip is small, the bending strength is low, and when the number of reciprocating movements is large, the bending strength can be evaluated as high. In this way, strength can be evaluated based on the number of reciprocating movements.

For example, as described above, when grinding is performed by the grinding device 70 shown in FIG. It is also possible to evaluate the difference in intensity. More specifically, for example, a package substrate ground under the first processing conditions and a package substrate ground under the second processing conditions are prepared, and the chip strength of each package substrate is compared to determine the processing conditions. is to evaluate In addition, evaluation methods other than those described in this specification are conceivable and are not particularly limited.

Further, for example, as shown in FIGS. 9A to 9C, relative bending strengths may be compared for a plurality of chips 10A, 10B, and 10C arranged in the same row. First, pressing is started in the state shown in FIG. 9(A), and the package substrate 1 is moved until it reaches the state shown in FIG. 9(B). At this time, each of the chips 10A, 10B, and 10C is subjected to a load by pressing once, and the chip 10A in which the fracture is detected can be made the weakest in bending strength.

Next, the state shown in FIG. 9B changes to the state shown in FIG. 9C, and when the breakage of chip 10B is detected, chip 10B has the second highest bending strength, and chip 10C has the highest bending strength. can be evaluated as high.

Furthermore, as shown in FIG. 9(B), the chips in the first row 10M are reciprocated twice while a load is applied by the pressing roller, while the chips in the second row 10N are loaded by the pressing roller. It is also possible to compare how the chips are destroyed depending on the number of reciprocating motions, such as four reciprocating movements.

Note that, as in the first row 10M and the second row 10N shown in FIG. 9B, each row is reciprocated to evaluate the strength of the chips in each row. may be reciprocated so as to apply a load to all the chips.

Alternatively, the evaluation equivalent to the three-point bending test may be performed by destroying the chip only by pressing without executing the reciprocating step. At this time, in addition to measuring the load with the above-described load cell, a spring balance may be attached to measure the load at the time of breakage.

Further, as shown in FIG. 7B, a temperature detection unit 54 is arranged near the upper surface observation device 51 and near the pressing unit 40 to detect the temperature of the entire package substrate 1 as a test piece and the temperature of the test object. The temperature data of the chip 10 may be acquired.

As described above, it is possible to measure the chip strength of a test piece obtained by preparing a package substrate and thinning it, and to evaluate processing conditions during thinning. Furthermore, by attaching a protective tape to the surface of the chip, it is possible to prevent scattering of fragments when the chip is broken, and to prevent dust generated when the chip is broken from adhering to a roller or the like. As a result, it is possible to prevent debris from broken chips from adhering to the pressing roller or the like, adversely affecting the test, and making accurate evaluation impossible.

Further, according to the present invention, by appropriately selecting the material and thickness of the protective tape, it is possible to simulate a state in which the chip is embedded in the card. can be evaluated.

1 package substrate 2 testing device 10 semiconductor device chip 10 chip 10A chip 10B chip 10C chip 10D chip 12 base substrate 14 sealing resin layer 20 testing device 22 base 23 frame 30 test piece moving unit 32 moving base 34 support mechanism 35a collar 35b Flange lifting mechanism 36 Guide rail 38 Ball screw 39 Pulse motor 40 Pressing unit 41 Support roller 41a Support roller 42 Press roller 42a Support roller 43 Press roller moving unit 43a Body portion 43b Moving portion 44 Base plate portion 44a Bearing portion 44b Guide rail 44c Support Roller support part 45 Support table 45a Ball roller 50 Chip breakage detection unit 51 Upper surface observation device 52 Side observation device 53 Detection device 54 Temperature detection unit 70 Grinding device 71 Holding table 72 Tape 73 Grinding wheel 74 Grinding wheel 100 Controller C card

Claims (2)

A chip strength test method comprising:
a preparation step of preparing a package substrate having a base substrate, a chip arranged on the base substrate, and a sealing resin layer for sealing the chip;
a thinning step of thinning the sealing resin layer of the package substrate to expose the chip;
a tape applying step of applying protective tape to the package substrate to cover the exposed chip after performing the thinning step;
A pair of support rollers each having a rotation shaft extending in a first direction supports the lower surface of the package substrate on the side of the base substrate, and is disposed between the pair of support rollers and extends in the first direction. a pressing step of pressing the upper surface of the protective tape with a predetermined force with a pressing roller having a rotating shaft;
a reciprocating step of starting to reciprocate continuously the package substrate supported by the pair of support rollers and pressed by the pressure rollers in a second direction intersecting the pressure rollers;
a tip breakage detection step of detecting breakage of the tip after performing the reciprocating step. a data storage step of storing the time and/or the number of reciprocating movements required from the start of the reciprocating movement in the reciprocating step until the breakage of the chip is detected in the chip breakage detecting step;
The chip strength testing method according to claim 1, characterized in that:

Images