JPH0711556B2 - Electrostatic breakdown voltage test method and device - Google Patents

Description

The present invention relates to an electrostatic withstand voltage test method for semiconductor devices and an apparatus therefor.

(Prior Art) With high integration and miniaturization, MOSLSI is prone to electrostatic breakdown because the design pattern becomes as fine as 2 μm or less and the gate oxide film becomes thin as 35 μm or less. Diversification also contributes to electrostatic and destruction problems.

For example, since the flat package has a thin mold resin, the electrostatic capacitance of the package is large and the amount of electric charge tends to increase. In the case of chip-on-board, static electricity is directly charged on the chip. The charged static electricity destroys the gate oxide film and the junction.

The mechanism of this electrostatic breakdown phenomenon is that the circuit is destroyed when static electricity is charged on the package surface and discharged through the leads. Conventionally, as a test method for this kind of destruction phenomenon, there have been a human body discharge method, a charged device method and the like.

On the other hand, the present applicant has previously proposed a method of performing a destructive test by charging the package with electric charges (hereinafter, referred to as a package electrostatic destructive test method). This is described in detail in JP-A-60-73375 or Nikkei Electronics 1984/4/23.

By using this package electrification breakdown test method, it became easy to determine equivalent parameters in the electrostatic breakdown phenomenon due to package electrification, design device patterns, circuits, and package shapes with improved breakdown pressure.

(Problems to be solved by the invention) However, even after discharging, the electric charge remaining in the internal circuit causes electrostatic breakdown in the internal circuit, or the test device for testing the internal circuit malfunctions. There was such a problem as

(Means for Solving Problems) In order to solve the above problems, according to the present invention, after discharging a charge charged in a package of a semiconductor device by a discharge rod, the discharge rod is set to a predetermined size of the semiconductor device. The electric charge remaining in the internal circuit is removed by the static elimination terminal while being in contact with the external lead terminal, and then the static elimination terminal is connected to a test device for testing the internal circuit.

(Operation) According to the present invention, since the electric charge remaining in the internal circuit is eliminated by the static elimination terminal while keeping the predetermined external lead terminal and the discharge rod in contact with each other, the static elimination terminal is connected to the test device. At the time of static elimination, no reverse voltage is applied to the internal circuit to cause electrostatic breakdown, and there is no influence such as malfunction of the test apparatus.

(Examples) Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of an embodiment of the present invention.

In the figure, an electrostatic withstand voltage test apparatus 1 includes an IC2 to be tested, an application electrode 3 for applying a high DC voltage, and an IC2 to an IC2 package to be tested.
The discharge rod 4 that contacts the specified lead of the
It has a terminal 5a that contacts all the leads of 2 and removes the minute charge remaining in the circuit of IC 2 after the discharge is completed.

The application electrode 3 is connected to a direct current high voltage generator 6,
It is preferable that the high voltage generator 6 be capable of arbitrarily generating a voltage of about 0V to 3kV.

The discharge rod 4 has a slide mechanism, which uses a motor as a drive source, and can move onto an arbitrary lead by an operation in the X-Y directions, and can move with a predetermined lead by an operation in the Z direction (vertical movement). Contact and separate. Further, this discharge rod 4 is connected to the equivalent impedance means 7, which enables the IC
The discharge from 2 can be adjusted. Although the discharge rod 4 is illustrated as moving in the X-Y-Z directions in the drawing, the discharge rod 4 has a function of only vertical movement, and the table itself including the application electrode 3 is in the X-Y direction. May move. Further, the drive source is not limited to the motor, and air pressure or hydraulic pressure may be used.

The terminal 5a is fixed to the terminal block 5b and moves together with this terminal block 5b. The terminals 5a are connected to the ground potential, and at least the same number as the leads of the IC2 are prepared. By moving in the IC2 direction, it is possible to make contact with all the leads. IC2 is a dual in-line type package I
If the leads are led out in two directions like C, one set is prepared on the left and right, and if the leads are led out in four directions such as a chip carrier, one set is prepared in four directions. Needless to say, if the number of terminals 5a is not the same as the number of leads in the case of one set in four directions, it becomes difficult to contact the leads. In addition to the ground potential of the terminal 5a, if the switch 8 such as a relay can be switched to the tester 9, it is possible to immediately understand whether the electrostatic breakdown has occurred in the IC 2 in addition to the removal of the electric charge. This is preferable because the space for providing the terminals of the tester can be saved. However, it goes without saying that it is also possible to provide a terminal for a tester separately from the terminal 5a and thereby measure whether or not electrostatic breakdown has occurred. Although the connection of one of the terminals 5a is omitted in the drawing, it is the same as the other.

The test steps of the electrostatic breakdown voltage test apparatus 1 will be described below with reference to FIG.

(A) IC2 is loaded on the application electrode 3. Application electrode 3 is I
It is preferable to have a formwork that allows C2 to just fit in because it facilitates positioning.

The steps from (B) below are the steps of the electrostatic breakdown voltage test for each lead.

(B) A high voltage is applied to the application electrode 3.

(C) The discharge rod 4 is lowered to the designated lead as it is, and the discharge is caused. Then, the high voltage is cut off.

(D) The terminal 5a is pressed against the lead while the lead and the discharge rod 4 are in contact with each other to remove the electric charge remaining in the circuit of the IC2. The lead and the discharge rod 4 are kept in contact with each other because the electric charge is charged in the circuit due to the intrusion of the electric charge through the package due to the high voltage, and therefore the reverse voltage is applied when the electric charge is removed by the terminal 5a. This is to prevent electrostatic breakdown from occurring in areas other than the leads that have been subjected to such discharge.

After removing the electric charge in the circuit, the switch 8 is switched to connect to the tester 9 to inspect whether electrostatic breakdown has occurred. If the charges in the circuit are not removed here, the residual charges may cause the tester to malfunction or, in the worst case, destroy the tester.

(E) Separate the discharge rod 4 and the terminal 5a from the lead.

This completes one step of the electrostatic withstand voltage test for the predetermined lead. The steps (B) to (E) are repeated for each lead. Further, the voltage applied to the application electrode 3 is changed and the operation is repeated.

(F) After completing the electrostatic withstand voltage test for each lead, remove IC2 from the application electrode 3.

The electrostatic breakdown voltage test can be performed by such steps.

Next, the whole one embodiment of the electrostatic breakdown voltage test apparatus will be described in more detail with reference to FIG. The electrostatic withstand voltage test apparatus 1 includes a test table unit 31 including the application electrode 3 and the terminal block 5b described with reference to FIG. 1, a test table base 32, a drive unit 33 for transmitting power to the test table unit 31, and a discharge rod. 4
It is composed of a discharge rod driving base 34 which is moved onto an arbitrary lead of the IC2.

The test table unit 31 and the test table base 32 are constructed as shown in FIG.

Figure 4 (a) is a test table top 32, the lever L ₁ ~L ₈ which is a part of the drive unit 33 is displaying. A connector 1 for electrically connecting to the test table unit 31 is provided on the side.

(B) and (c) are the test table unit 31,
They are for PLCC and DIP, respectively. The test table unit 31 is provided with four holes 42 and is guided and fixed by the projections 43 provided on the test table base 32. Further, below the test table unit 31, another connector that fits with the connector 41 is provided, and the connector is arranged so that the connector connection is completed at the same time by fitting the hole 42 and the protrusion 43. Further, below the chuck 44 for pressing the terminal block 5 and the IC provided on the test table unit, the lever L ₁
~ The cam is protruding to the position corresponding to L ₈ and lever L ₁ ~
L ₈ Driven by the movement toward the center.

The PLCC test table unit (b) has four terminal blocks 5b so as to contact the leads led out in four directions of the PLCC, and also four chucks to press the four corners of the package.
It has a total of eight slide parts of 44. These are elastically supported in the direction opposite to the central direction, and are slid in this direction by the movement toward the central direction.

The test table unit (c) for DIP has a total of four slide portions, that is, a set of terminal blocks 5b that come into contact with leads arranged on the long side of the IC and a set of chucks 44 that press the short side of the IC.
These also have a structure that slides toward the center, but when they are operated, there is a part of the levers L _{1 to} L ₈ that does not have a corresponding slide portion, and this lever does not have to be driven.

As shown in FIG. 5, the drive unit 33 has three plate cams C _{1 to} C ₃ , which are arranged so as to be able to independently rotate about a coaxial axis, and motors M _{1 to} M ₃ respectively. Are each driven via a timing belt. Eight shafts are equidistantly arranged around the cam C on a concentric circle centered on this axis, and each shaft is rotatably supported by bearings. The upper end of each shaft is provided lever L ₁ ~L _8, L ₁ and L ₅ cam
To _{C 3, L 2, L 4} , L 6 and L ₈ is a cam C _1, L ₃ and L ₇ is cam C ₂
It is formed to follow each. A driven lever that is driven by the cam C is provided below each of the levers L ₁ to L ₈ . Since each of these levers is fixed to the shaft, the movement of the motor M transmitted via the cam C can be transmitted to the levers L _{1 to} L ₈ .

In this embodiment, the test table unit 31 can be easily replaced depending on the type and shape of the IC to be tested.
Even if a plurality of ICs having different package shapes have to be inspected, the inspection can be easily performed.

A modification of the embodiment will be described below.

In the embodiment, the chuck is used to fix the IC on the application electrode 3, but a small hole may be formed in the application electrode 3 and vacuum suction may be performed by vacuuming from this hole. Further, the terminal 5a is divided for each lead in order to serve also as the terminal of the tester, but if the tester terminal is separately provided, it may be a plate-like one extending over all the leads, thereby removing charges in the circuit of the IC. be able to.

(Effect of the Invention) According to the present invention, an electrostatic breakdown voltage test of a semiconductor device can be easily realized without causing electrostatic breakdown in an internal circuit and further without affecting a test device. .

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an electrostatic withstand voltage test apparatus for explaining an embodiment of the present invention, FIG. 2 is a flow chart for explaining the test steps, and FIG. 3 is an electrostatic withstand voltage test apparatus. 4 is a perspective view showing the whole of FIG. 4, FIG. 4 is a perspective view showing a combination of a test table unit and a test table base, and FIG. 5 is a perspective view showing a drive unit. 1 …… Electrostatic withstand voltage tester, 2 …… IC, 3 …… Applying electrode,
4 ... Discharge rod, 5a ... Terminal, 5 ... Terminal block, 6 ... High voltage generator, 7 ... Equivalent impedance means, 8 ... Switch.

Claims (2)

[Claims] 1. A step of charging a package of a semiconductor device having an internal circuit and a plurality of external lead terminals with an electric charge applied from an applying electrode, and a resistance means is provided to a predetermined external lead terminal among the plurality of external lead terminals. A step of contacting a discharge rod connected to a ground potential via the discharge rod to discharge the electric charge charged inside the package from the predetermined external lead terminal, and thereafter, the discharge rod is connected to the predetermined external lead terminal. In contact with the plurality of external lead terminals, the plurality of static elimination terminals provided corresponding to each of the plurality of external lead terminals are brought into contact with the plurality of external lead terminals to eliminate the electric charges remaining in the internal circuit. And a step of connecting the static elimination terminal to a test device for testing the internal circuit. 2. A discharge rod connected to a ground potential via a resistance means, and an application electrode for applying a charge to a package of a semiconductor device having an internal circuit and a plurality of external lead terminals, the discharge rod being connected to a ground potential. A discharge rod that contacts a predetermined external lead terminal of the external lead terminals and discharges the electric charges charged inside the package from the predetermined external lead terminal; and a test device for testing the internal circuit or the ground potential. A plurality of static elimination terminals that are selectively connected to one of the plurality of external lead terminals and are provided corresponding to the plurality of external lead terminals, respectively, wherein the discharge rod and the predetermined external lead terminal are formed after discharge by the discharge rod. When in a contact state, it is connected to the ground potential, contacts the plurality of external lead terminals, removes the electric charge remaining in the internal circuit, and after removing the charge, connects to the test device. Electrostatic withstand voltage testing device of the semiconductor device and having a plurality of static eliminating terminals.