JP2008187023A - Test method and test device for semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a test method and a test device for a semiconductor wafer by which a test can be conducted in a state that the contact resistance of a probe and a test pad of the semiconductor wafer is reduced to a reference value and the test can be conducted with contact resistance which is always the same. <P>SOLUTION: The method is provided with a step 13 for performing alignment for correcting a position of a dummy pad with respect to the probe of the semiconductor wafer on the test device, a step 14 for performing probing for bringing the probe of a probe card into contact with the dummy pad after alignment, a step 15 for measuring the contact resistance of the dummy pad after probing, a reference value comparing step 18, a step 16 for bringing an over drive amount to a certain constant value, a series of steps 17 comprising the steps 15, 16 and 18, and a step 19 for conducting the test on the semiconductor wafer by bringing the probe into contact with the test pad based on a comparison result of the contact resistance and the reference value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for testing a semiconductor wafer and a test apparatus for performing this test in a semiconductor device manufacturing process.

  The wafer test in the manufacturing process of the conventional semiconductor device is performed in a flow excluding step 17 shown in FIG. First, alignment (step 13) for correcting the pad of the test chip with respect to the probe needle is performed by a camera in the prober that performs probing in which the probe needle is brought into contact with the pad. Next, the probe needle is brought into contact with the test pad of the test chip formed on the semiconductor wafer by moving the stage in the prober in the XYZ directions (step 14). Thereafter, the semiconductor wafer is tested (step 19).

In such a conventional wafer test, the amount of overdrive during probing is determined by taking into account the bonding pad size of the semiconductor wafer, the probe needle tip size, the scrub amount, the position of the prober and the probe card, etc. The amount of overdrive represents the amount by which the tip of the probe needle is brought close to the surface of the semiconductor wafer in order to change the contact state between the semiconductor wafer and the pad, and the amount is usually in the range of about 1 to 100 × 10 ⁻⁶ m. Based on the amount of overdrive, the probe needle and the pad are brought into contact with each other for testing. However, testability in DC characteristics tests such as IOH / IOL is reduced due to the influence of the existing contact resistance, the number of probing times, and the contact resistance between the probe needle and the chip pad due to the difference in the test wafer, which leads to the deterioration of the yield. ing.

Japanese Patent Application Laid-Open No. H10-228561 provides a means for stabilizing the contact pressure by appropriately adjusting the overdrive amount of the measurement probe of the probe card, thereby reducing the contact resistance. In a probe card comprising a measurement probe to be brought into contact with a terminal of a semiconductor element formed on a semiconductor wafer and a substrate to which the measurement probe is attached, a dummy probe is provided in a region outside the probe installation region of the measurement probe on the substrate. The end surface of the end portion of the dummy probe is used as a reference surface serving as a reference for setting the distance between the terminal of the semiconductor wafer and the tip of the measurement probe. The height of the probe card can be easily measured, and even when a vertical misalignment occurs in the inspection device, it is possible to press the measurement probe against the terminal with an appropriate amount of overdrive and contact resistance. As a result, the electrical inspection of the semiconductor wafer can be performed accurately and the defect rate of the normal product of the semiconductor device as the product can be reduced.
JP 2006-153620 A

  The present invention has been made to solve the above problems, and it is possible to test in a state in which the contact resistance between the probe needle and the test pad of the semiconductor wafer is reduced to a reference value. Provided is a test method for a semiconductor wafer that can be tested with the same contact resistance, and a test apparatus used for carrying out the test method.

  According to one aspect of the method for testing a semiconductor wafer of the present invention, a semiconductor wafer having at least one test pad and at least one contact resistance measurement dummy pad is used to obtain a probe card having a probe needle and a contact resistance. In a semiconductor wafer test method for testing by a test apparatus having a function of applying a current or voltage to a probe needle and measuring the voltage or current, the dummy pad for the probe needle of the semiconductor wafer is provided in the test apparatus. Performing alignment for correcting the position; performing probing for bringing the probe needle of the probe card into contact with the dummy pad after the alignment step; and measuring contact resistance of the dummy pad after the probing step; Comparing the measured contact resistance of the dummy pad with a preset reference value, and based on a comparison result between the contact resistance and the reference value, the probe needle is brought into contact with the test pad to And a step for testing.

  In one aspect of the semiconductor wafer test apparatus of the present invention, in order to obtain a contact resistance, a probe card having a probe needle in contact with a predetermined dummy pad of a semiconductor test wafer having at least one contact resistance measurement dummy pad, A tester that applies a current or voltage to the probe needle and measures the voltage or current; and a prober that performs probing to bring the probe needle of the probe card into contact with the dummy pad, and the measured contact resistance is When the reference value is not reached, the contact state between the probe needle and the dummy pad is changed until the contact resistance between the probe needle and the dummy pad reaches the reference value.

  With the above configuration, the present invention makes it possible to perform a test with the contact resistance between the probe card and the test pad of the semiconductor wafer reduced to the reference value, and always allow the test to be performed with the same contact resistance. Become.

  Hereinafter, embodiments of the invention will be described with reference to examples.

First, Embodiment 1 will be described with reference to FIGS.
FIG. 1 is a plan view of a test semiconductor wafer of Example 1, FIG. 2 is a semiconductor wafer test apparatus used in Example 1, FIG. 3 is a flowchart of a wafer test method described in Example 1, and FIG. FIG. 5 is a cross-sectional view of a semiconductor wafer adjacent to a probe card that explains the amount of overdrive in Example 1, and FIG. 5 shows the contact resistance and overdrive amount of the probe needle formed on the probe card with respect to the semiconductor wafer of Example 1. It is a conceptual diagram explaining the relationship.

  A dummy pad for contact resistance measurement is provided on the test semiconductor wafer. The probe card is provided with a contact resistance measuring probe needle having the same height as the test probe needle, and the probe needle and the dummy pad are brought into contact with each other during probing. A tester constituting the semiconductor wafer test apparatus is provided with a function for measuring contact resistance, and the contact resistance is measured, and the amount of overdrive of the prober constituting the semiconductor wafer test apparatus is changed until a certain reference value is reached. When the contact resistance reaches the reference value, the semiconductor wafer test is started. By this method, before starting the test, the contact resistance between the probe needle for wafer test and the test pad is the same as the reference value. It becomes possible to test.

  FIG. 1 shows a test semiconductor wafer 1 made of a semiconductor such as silicon. A semiconductor wafer 1 is divided into a plurality of chip patterns 2, and a semiconductor integrated circuit is built in the chip pattern 2. The semiconductor wafer 1 is diced along a scribe line after the test to form a plurality of chips. Each chip pattern 2 has at least one contact resistance measurement dummy pad 3 together with a test pad (not shown). The dummy pad 3 is made simple so as not to be affected by the process, and consideration is given so that the contact resistance does not fluctuate due to the difference of the dummy pad. The dummy pad 3 is not electrically connected to a semiconductor integrated circuit formed in the chip.

  FIG. 2 shows a test semiconductor wafer and a semiconductor wafer test apparatus. The test device includes a tester 11 and a prober device 4. The tester 11 includes a contact resistance measurement unit 12 and a probe card 10. The probe card 10 has a probe needle 9 for measuring contact resistance. The prober device 4 includes a stage control unit 5, a stage drive unit 6, a command response interface 7, and a chuck 8.

  The test semiconductor wafer 1 mounted on the prober device 4 is held by a chuck 8. The contact resistance measuring unit 12 of the tester 11 applies a current or a voltage to the contact resistance measuring probe needle 9 to determine the contact resistance, and measures the voltage or current. The command response interface 7 is connected to the contact resistance measuring unit 12 and makes it possible to change the overdrive amount until the contact resistance value reaches a certain reference value. The stage controller 5 is instructed by the command response interface 7 to drive the stage driver 6. The movement of the stage drive unit 6 allows the stage 8 to move and move up and down in the X and Y directions. The height of the tip of the probe needle 9 for contact resistance measurement is the same as that of the probe needle for wafer test.

  FIG. 4 is a cross-sectional view showing a test semiconductor wafer for explaining the amount of overdrive in the semiconductor wafer test method and a probe card having a probe needle adjacent to the test semiconductor wafer. The probe card 10 has a probe needle. The probe needle has a contact resistance measuring probe needle 9 and a wafer test probe needle 20, and the needle tips thereof are a dummy pad 3 and a wafer test pad 21 formed on the semiconductor wafer 1 by lowering of the probe card 10, respectively. To come into contact.

The relationship between the contact resistance of the probe needle with respect to the test semiconductor wafer and the amount of overdrive will be described with reference to FIG. The vertical axis represents the contact resistance, the horizontal axis represents the overdrive amount (Δh) (× 10 ⁻⁶ m), and the contact resistance-overdrive amount curve B is shown in the figure. As shown in FIG. 4, the contact resistance is measured by probing while the probe needle 9 of the probe card 10 is in contact with the dummy pad 3 of the semiconductor wafer. At this time, a certain reference value A (which is as close to 0 as possible) is set and compared with this contact resistance. When the contact resistance value does not reach the reference value A, the probe needle 9 is pressed against the dummy pad in order to further increase the contact of the probe needle 9 with the dummy pad 3 and lower the resistance. The distance is called an overdrive amount (Δh), and is changed in a range of about 1 to 100 × 10 ⁻⁶ m.

  A flow showing a semiconductor wafer test method will be described with reference to FIG. In the conventional wafer test, alignment is performed by correcting the pad of the test chip with respect to the probe needle using the camera in the prober apparatus, and the probe needle is brought into contact with the pad of the test chip by moving the stage in the prober apparatus in the XYZ directions ( After the probing), a wafer test was performed. In this embodiment, step 17 of FIG. 3 is added to this conventional test procedure.

  The test of the semiconductor wafer of this embodiment is started. First, using a camera (not shown) in the prober device 4, alignment is performed to correct the pad of the test chip with respect to the probe needle implanted in the probe card 10 (step 13). Next, the stage in the prober apparatus 4 is moved in the XYZ directions to bring the contact resistance measuring probe needle 9 into contact with the pad of the test chip (step 14). The height of the probe tip 9 of the contact resistance measuring probe needle 9 is the same as that of the wafer test probe needle 20 (see FIG. 4).

  Next, the contact resistance is measured with the contact resistance measuring probe needle 9 and the dummy pad 3 of the test chip 2 in contact with each other (step 15). A reference value (see FIG. 5) from which it can be determined that the contact resistance is sufficiently low is provided in advance, and whether or not the measured contact resistance has reached the reference value is compared (step 18). If this contact resistance has reached the reference value, a wafer test is started (step 19). If the contact resistance does not reach the reference value, the overdrive amount (Δh) is changed by a certain value (step 16). Then, the contact resistance is measured again (step 15) and compared with the reference value (step 18). This resistance measurement-comparison with reference value-overdrive amount change is repeated until the contact resistance reaches the reference value (step 17).

By performing step 17 prior to the wafer test, the contact resistance between the probe needle 9 for contact resistance measurement and the test probe needle and the test pad having the same needle tip height is also the same as the reference value, thus reducing the contact resistance. Can be tested. In addition, by providing a reference value for starting a test for the contact resistance value, it is possible to suppress a variation in contact resistance due to the number of probing times, test chips, and lots, and always perform a test with the same contact resistance value. .
In this way, electrical inspection of the chips 2 formed on the semiconductor wafer 1 is performed, and the semiconductor wafer 1 that has been inspected is divided into chips 2 formed for each chip 2 formed therein, A semiconductor device is manufactured through an assembly process.

Next, Example 2 will be described.
The test method shown in FIG. 3 may be operated every time a single semiconductor wafer is installed, or may be performed periodically, for example, for each semiconductor wafer production lot or as necessary. .
This embodiment is characterized in that contact resistance is measured for each chip using the test apparatus shown in FIG. By measuring the contact resistance of the chip existing locally in the semiconductor wafer, it is possible to suppress the fluctuation of the contact resistance caused by the warp of the semiconductor wafer to be tested.

1 is a plan view of a test semiconductor wafer of Example 1. FIG. The semiconductor wafer test apparatus used in the first embodiment. 1 is a flowchart of a wafer test method described in Example 1. FIG. Sectional drawing of the semiconductor wafer which the probe card explaining the amount of overdrive in Example 1 adjoined. The conceptual diagram explaining the relationship between the contact resistance of the probe needle formed in the probe card with respect to the semiconductor wafer of Example 1, and the amount of overdrive.

Explanation of symbols

1 ... Semiconductor wafer for test 2 ... Chip pattern (chip)
DESCRIPTION OF SYMBOLS 3 ... Dummy pad for contact resistance measurement 4 ... Prober device 5 ... Stage control part 6 ... Stage drive part 7 ... Command response interface 8 ... Chuck 9 ... For contact resistance measurement Probe needle 10 ... Probe card 11 ... Tester 12 ... Contact resistance measurement unit 13 ... Alignment step 14 ... Probing step 15 ... Contact resistance measurement step 16 ... Overdrive amount change step 17 ... A series of steps including steps 15, 16, and 18 18 ... Reference value comparison step 19 ... Test start step

Claims (5)

A semiconductor wafer having at least one test pad and at least one contact resistance measurement dummy pad is applied to a probe card having a probe needle and a current or voltage is applied to the probe needle to obtain a contact resistance. In a semiconductor wafer test method for testing by a test apparatus having a tester having a function of measuring,
Performing an alignment for correcting the position of the dummy pad with respect to the probe needle of the semiconductor wafer in the test apparatus;
Probing for bringing the probe needle of the probe card into contact with the dummy pad after the alignment step;
Measuring the contact resistance of the dummy pad after the probing step;
Comparing the measured contact resistance of the dummy pad with a preset reference value;
And a step of testing the semiconductor wafer by bringing the probe needle into contact with the test pad based on a comparison result between the contact resistance and a reference value.   When the measured contact resistance does not reach the reference value, the contact state between the probe needle and the dummy pad is changed until the contact resistance between the probe needle and the dummy pad reaches the reference value. The method for testing a semiconductor wafer according to claim 1.   3. The method for testing a semiconductor wafer according to claim 1, wherein a plurality of the probe needles are provided in the probe card, and the plurality of probe needles have the same needle tip height. .   The semiconductor wafer has a plurality of chips, and by measuring the contact resistance of the dummy pad for each of these chips, the fluctuation of the contact resistance caused by warpage of the semiconductor wafer is suppressed. The method for testing a semiconductor wafer according to claim 1. A probe card having a probe needle in contact with a predetermined dummy pad of a semiconductor test wafer having at least one contact resistance measurement dummy pad;
In order to determine the contact resistance, a tester that applies a current or voltage to the probe needle and measures the voltage or current;
A prober that performs probing to bring the probe needle of the probe card into contact with the dummy pad;
When the measured contact resistance does not reach the reference value, the contact state between the probe needle and the dummy pad is changed until the contact resistance between the probe needle and the dummy pad reaches the reference value. Semiconductor wafer testing equipment.

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