JP3434946B2 - Charged particle beam test equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a chip electrode (bonding pad) of a test wafer placed on a moving stage and an electrical contact with a chip electrode (bonding pad) in the charged particle beam test apparatus when the chip of the test wafer is placed on the moving stage. The present invention relates to a contact control device with a contacting probe card.

[0002]

2. Description of the Related Art As shown in FIGS. 4, 5, 6 and 7 of the prior art, the contact technology between a plurality of bonding pads on a wafer under test and a probe card which makes electrical contact with the bonding pads will be described below. explain.
This contact technique is mainly used in a charged particle beam test apparatus (for example, an electron beam test system) or a prober apparatus. The conventional overall structure is shown in FIG. As shown in FIG. 6, the main part configuration diagram relating to the invention in this configuration includes a probe card 150, a stage control unit 300, a wafer stage 400, an ICT 500, and a test head 600.

The probe card 150 is a
A plurality of probe pins, which are stylus, are arranged corresponding to the positions of the bonding pads of the chip under test to provide electrical contact, and a measurement signal on the test head 600 side is used as a connection interface.

The ICT500 is a semiconductor test device,
A power source and a test pattern signal are supplied to each bonding pad of the chip under test 100 via the test head 600 and the probe card 150.
A predetermined device analysis / test is performed together with the charged particle beam test apparatus in response to the output signal from the device.

As shown in FIG. 4, the main body of the charged particle beam testing apparatus has a probe pin 1 of a probe card 150 on each bonding pad 110 of a chip under test 100 on a wafer.
52 is brought into contact with the power supply and the test signal from the ICT 500 is applied, and the charged particle beam is applied to a desired position in a vacuum state to analyze the potential distribution of the chip under test 100 in a non-contact manner.

The wafer stage 400 holds the above-mentioned wafer and is controlled by the stage control unit 300 so that the vertical and horizontal directions (X, Y,
It is a movable stage movable in the Z) direction, and in order to make contact (electrical contact) between the chip bonding pad 110 and the probe pin 152, this stage is vertically moved in the Z-axis direction to measure the electrical contact. There is a need.

Here, a large number of probe pins 152 are arranged adjacent to each other on the probe card 150. A fine tungsten metal needle having elasticity is mainly used for this pin, and it is repeatedly contacted and stressed every chip test.

Conventionally, the method of setting a predetermined contact position is such that an operator uses a scope or SEM (scanning electron).
microscope) While viewing the image, etc., the stage controller 3
The Z-axis of the wafer stage 400 is gradually raised / lowered by setting the contact position to be a predetermined contact position. That is, by using the contact check function of the ICT for each Z-axis inching, after confirming the contact position, that is, the first touch position 71, the height to which an overdrive amount 72 is added to give a stable contact stylus pressure is added. The procedure was to set the Z axis.

As shown in FIG. 5, the first touch position 71 is a Z-axis boundary point where the probe pin 152 comes into contact with the bonding pad 110 and PASS the contact check, and the overdrive amount 72 is used. Is an amount of movement that gives a needle pressure for stable contact with the probe pin from the first touch position 71, and this overdrive amount 72 differs depending on the type (structure / shape) of the probe pin of each probe card 150.

Here, the contact check function of the ICT is a function of checking whether the probe pins and the bonding pads of the chip are really in an electrically connected state.
As the contact check result, PASS / FAIL information indicating whether or not all the pins are in contact with each other, information on whether or not there is a short circuit with an adjacent pin, and contact information for each individual pin are also obtained. However, this check function cannot measure the value of contact resistance.

As described above, in order to set the optimum contact position, it is necessary to perform a contact check by repeatedly performing contact check by the ICT while moving the pins in a stable manner in order to contact all the pins stably. Further, the probe pin is often stressed due to the frequency of use of contacts of a large number of chips, and is deformed or needle misaligned in the vertical direction, so that each tip is not at the same height position in many cases.

Further, since the conventional contact is manually operated by the operator, it may be operated beyond the overdrive amount 72 depending on the above operation, which causes excessive deformation stress and damages the tip portion. ,
It has a drawback that it tends to be short-circuited by bending to the adjacent pin side, shortening the life of the probe pin, and the like. In order to prevent these occurrences, careful contact operation is always required.

[0013]

As described above, conventionally, each probe pin of the probe card 150 is manually set to move to the optimum contact position, so that it takes a long time to set and the probe pin is excessively moved. There is a situation in which the power is applied to accelerate or damage the deterioration, or a contact error is caused to cause a chip test error, which is a difficulty in performing stable contact between the bonding pad and the probe pin.

Therefore, an object to be solved by the present invention is to realize an automatic contact control function between a bonding pad and a probe pin to realize stable and reliable contact in a short time.

[0015]

First, in order to solve the above-mentioned problems, in the configuration of the present invention, until the contact check result from the IC test system becomes the PASS state,
Control means for moving closer in the contact direction in a predetermined overdrive amount 72 unit corresponding to the type of the probe pin 152, and to a position where the contact check result from the IC test system becomes a FAIL state after the contact check result is PASS. , 73 units of fine movement amount (that is, a movement amount corresponding to a predetermined required accuracy amount) in the non-contact direction, and 73 units of fine movement amount up to the first touch position where the contact check result becomes the PASS state again. The control means moves closer to the contact direction and the control means moves the overdrive amount 72 from the first touch position 71 to the contact direction.
As a result, the bonding pad 1 of the wafer under test is tested by the IC test system having the contact check function.
The automatic contact between the bonding pad and the probe pin is realized in the contact with the probe pin 152 of the probe card 150 which makes an electrical contact with 10.

Secondly, in order to solve the above problems, in the configuration of the present invention, the probe pin 15 is kept until the contact check result from the IC test system becomes the PASS state.
Control means for moving closer in the contact direction by a predetermined overdrive amount of 72 units corresponding to the two types, and after the contact check result is PASS, from the position where the contact check result from the IC test system becomes the FAIL state, the PASS is restarted. A halving movement control means by a binary search method up to the first touch position where
Overdrive amount 72 from the first touch position 71
There is a control means for moving in the contact direction. As a result, an automatic contact with a reduced number of fine movements for obtaining the first touch position 71 is realized.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to Examples.

[0018]

A peculiar point of the present invention is that the probe pin is controlled by receiving a signal from the ICT for each contact check result and controlling the Z-axis by a safe movement distance unit (that is, overdrive amount 72). The point is to automatically set a stable and reliable contact means that does not apply excessive stress as an automatic control means that does not apply excessive stress to.

Example 1 FIG. 1 shows an example of the present invention.
This will be described below with reference to FIGS. 3 and 8. The overall structure of the present invention is shown in FIG. As shown in FIG. 3, the main part configuration diagram relating to the present invention in this structure is such that the ICT, the signal line of the stage control part, and the automatic contact control part 50 are added to the conventional main part structure. Automatic contact control unit 50
Performs the contact by automatically controlling the Z-axis stage according to the following description while performing the contact check.

In the first step, the bonding pad 110 and the probe pin 152 are brought into contact with each other. That is,
As shown in the procedure for moving the Z-axis stage in FIG. 1, the contact check function of the ICT is activated after starting from the initial position and raising the overdrive amount corresponding to the probe pin 152 to 72 units. If the check result indicates that the FAIL state is still present, the overdrive amount is increased again by 72 units and the same operation is repeated as shown in the figure. Eventually, the contact check results PASS at the position shown.

In the second stage, the first touch position 71 which is the boundary of the contact is obtained. That is, as shown in the figure, the distance is lowered by 73 units of fine movement amount (that is, the movement amount corresponding to a predetermined required precision amount), and the result of the contact check is received. Perform inching. Eventually, the contact check result will fail at the position shown. The contact check result is again moved to the PASS state in the contact direction in the unit of fine movement 73. As a result, this position is obtained as the first touch position 71.

In the third stage, in order to provide stable contact,
The illustrated overdrive amount 72 is moved upward from the first touch position 71, and the needle pressure for stable contact with the probe pin is given to end the automatic control.

As described above, the automatic contact control means for inching control to the overdrive amount 72 unit which is a safe movement unit for Z-axis movement gives excessive stress to the probe pin 152. It is possible to realize an automatic contact setting means without worry.

(Embodiment 2) In the description of obtaining the first touch position 71 in the second stage of Embodiment 1 described above, the amount of fine movement 7
Although it was a movement control method of descending every 3 units, the number of fine movements may increase. The method described below is an example of reducing the number of times of this inching.

That is, instead of using the unit of the fine movement amount 73 as the movement amount, as shown in FIG. 2, the halving movement control method by the binary search method is used. That is, in the movement step shown in the figure, the downward movement is performed by 1/2 the movement amount of the overdrive amount 72, and if it is still in the contact state, the overdrive amount 72 is set to 1/2 of the further movement amount as in the movement step shown in the figure. ½ × ½ = 1/4 The amount of movement is lowered. Here, when the contact state becomes FAIL, as shown in the figure, 1/2 × 1/2 × 1/2 of the overdrive amount 72 which is 1/2 of this movement amount =
Move up in the opposite direction with a movement amount of 1/8.

By repeating this binary search operation, when the movement amount reaches less than the desired fine movement amount, that position is determined as the first touch position 71.
Such a binary search movement control means may be provided in the automatic contact control section 50.

[0027]

Since the present invention is configured as described above, it has the following effects. I
Contact check result from C test system is PA
Until the SS state is reached, a safe overdrive amount of 72 units is controlled to approach and move in the contact direction to the position where the contact check passes, then to the first touch position 71, the fine movement amount is controlled to 73 units, and finally. From the first touch position 71 to the overdrive amount 72
By making the control means to move in the contact direction,
Bonding pad 11 of wafer under test safely in a short time
It is possible to automatically set good electrical contact between 0 and the probe pin 152.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a step of moving a Z-axis stage according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a step of moving a Z-axis stage according to a second embodiment of the present invention.

FIG. 3 is a structural diagram of a main part constituting a contact implementation between a probe card and a bonding pad of the present invention.

4 is a perspective view showing a contact relationship between a plurality of probe pins and a plurality of bonding pads of the chip under test 100. FIG.

FIG. 5 is a diagram illustrating a first touch position 71 and an overdrive amount 72.

FIG. 6 is a structural diagram of a main part that constitutes a conventional contact implementation between a probe card and a bonding pad.

FIG. 7 is an overall configuration diagram of a conventional charged particle beam test apparatus.

FIG. 8 is an overall configuration diagram of a charged particle beam test apparatus of the present invention.

[Explanation of symbols]

50 Automatic contact control unit 71 First touch position 72 Overdrive amount 73 Fine movement 100 chips under test 110 bonding pad 150 probe card 152 probe pin 300 stage controller 400 wafer stage 500 ICT (IC test system) 600 test head

─────────────────────────────────────────────────── --Continued from the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01R 31/31-31/3193 G01R 31/26

Claims (2)

(57) [Claims] 1. An IC defect in which a wafer under test is irradiated with a charged particle beam, a potential distribution inside the IC is acquired as an SEM image from the emission amount of secondary charged particles at an irradiation point, and a defective portion inside the IC is searched. In the analysis device, the contact check result from the IC test system is P
Until the ASS state is reached, probe pins are used in units of a predetermined overdrive amount (72) corresponding to the type of probe pin.
The trial in the Z-axis direction both the wafer to be tested is Contacts
A first control means for moving the wafer stage (400) for holding the test wafer, after the contact check result is PASS, the IC
Contact check result from test system is FAI
L state to become first touch position (71) up, moving of the wafer stage in the non-contact direction fine inching amount units
And a second control unit for controlling the wafer step in the contact direction to which the overdrive amount (72) is applied from the first touch position (71).
A charged particle beam test apparatus comprising: a third control means for moving the charge and the above. 2. An IC defect in which a wafer under test is irradiated with a charged particle beam, the potential distribution inside the IC is acquired as an SEM image from the amount of secondary charged particles emitted at the irradiation point, and a defective portion inside the IC is searched. In the analysis device, the contact check result from the IC test system is P
Until the ASS state is reached, probe pins are used in units of a predetermined overdrive amount (72) corresponding to the type of probe pin.
In the direction in which both the wafer under test and the wafer under test are in contact, the wafer under test
Move the wafer stage (400) holding the stack
After the contact check result is PASSed with the first control means, the wafer stage is moved based on the binary search method to the first touch position (71) where the contact check result from the IC test system becomes the FAIL state, and the contact is detected.
Control method to check the wafer stage
The first amount of movement in the contact direction is over
Amount of movement of 1/2 of live amount (72), and amount of movement after that
Is the movement amount that is half the previous movement amount in the contact direction
Or by moving the upper blade stage to the non-contact direction
The contact check operation is repeatedly executed to
The halving movement control means for specifying the last touch position (71) and the wafer step in the contact direction to which the overdrive amount (72) is applied from the first touch position (71).
A charged particle beam test apparatus comprising: a third control means for moving the charge and the above.