JPH0414933Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in a prober for inspecting and measuring the electrical characteristics of semiconductor pellets formed on a wafer.

[Conventional technology]

Conventionally, when inspecting and measuring the electrical characteristics of semiconductor pellets formed on a wafer, a prober as shown in FIG. 5 has generally been used. In this prober, an upper electrode needle 10 is placed above a disc-shaped chuck table 100 having suction holes.
1, this chuck table 10
The chuck table 100 is used as a terminal to make electrical contact with the electrode layer on the back surface of the wafer W.
is raised to bring the electrode on the surface of the pellet to be tested on the wafer W into electrical contact with the upper electrode needle 101, thereby inspecting and measuring the electrical characteristics of the pellet to be tested. However, when using this prober,
Electrode layer on the back side of wafer W and chuck table 100
There was a problem that the contact resistance between the two affected the measurement.

Therefore, as shown in FIG. 6, the chuck table 100 is electrically divided into two parts with an insulator 102 in between, and one part is used as a sensing terminal 103 and the other part is used as a facing terminal 104, thereby making a Kelvin contact. An improved prober was developed. When Kelvin contact is established in this way, the above-mentioned problem of contact resistance is solved, and when the electrical resistance of the electrode layer on the back surface of the wafer W is low, a good electrical connection is achieved.

[Problem that the invention attempts to solve]

However, in the above-mentioned improved prober, the current flows through the electrode layer on the back surface of the wafer W up to the contact point during measurement, so if the electrical resistance of the electrode layer is large, the voltage drop will cause a voltage drop. This causes a problem in that errors occur in the measured values. This problem is particularly serious when the pellet to be tested is a power transistor or the like that must be inspected or measured by passing a large current, and cannot be ignored.

[Means for solving problems]

In order to solve the above problem, the prober of the present invention has a wafer support frame that supports a wafer on which a large number of semiconductor pellets have been formed, between a back electrode needle that can move up and down and an upper electrode needle that is placed directly above it. The wafer support frame is provided movably in horizontal and vertical directions, the wafer support frame is used as a facing terminal, the back electrode needle is used as a sensing terminal, and the wafer is configured to make Kelvin contact with the directly back side of the pellet to be tested. It is something.

[Effect]

According to the inventive prober having the above configuration, when the wafer support frame moves in the horizontal direction and the pellet to be tested on the wafer is positioned directly above the back electrode needle (in other words, directly below the upper electrode needle), the pellet is used as a sensing terminal. The working back electrode needle rises and comes into contact with the back side of the pellet to be tested, making Kelvin contact. Then, the wafer support frame rises, and at the same time, the back electrode needle also rises, and while the back electrode needle remains in contact with the right back side of the pellet to be tested, the electrode of the pellet to be tested comes into contact with the upper electrode needle, and the electrical characteristics are measured. Inspections and measurements are carried out.

By making Kelvin contact on the back side of the wafer to be tested in this way, current will flow through the electrode layer on the back side of the wafer in the thickness direction during measurement, even if the electrical resistance of the electrode layer is large. Almost no voltage drop occurs.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a prober according to an embodiment of the present invention. In the figure, 1 is a base, and a support plate 3 is provided on the base 1 via a drive mechanism 2 in the X-Y-Z directions. This support plate 3 has columns 4, 4 at both ends, and an annular wafer support frame 5 is supported and fixed by these columns 4, 4.

This wafer support frame 5 serves as a facing terminal when making a Kelvin contact as described later, and as shown in FIGS. 2 and 3, it has an inner flange 5a that supports the wafer W, It is composed of an outer peripheral wall 5b that prevents protrusion and integral mounting protrusions 5c, and an intake passage 5d is formed inside the outer peripheral wall 5b, and an intake passage is formed on the upper surface of the inner flange 5a. A large number of suction holes 5e for wafer suction are formed in series with each other. However,
As shown in FIG.
It is movable in the -Y-Z directions, that is, in the horizontal and vertical directions.

An electrically insulating needle container 8 is attached to the intermediate support 6 located below the wafer support frame 5 via a vertical drive mechanism 7.
A back electrode needle 9 is housed in. This back electrode needle 9 serves as a sensing terminal when making a Kelvin contact as described later, and has a flange 9a in the middle as shown in FIG. The needle is supported by a coil spring 10 mounted between the needle and the bottom surface of the container 8, and is housed in the needle container 8 with the tip of the needle slightly protruding from the upper opening of the needle container 8. Therefore, when the needle container 8 is raised by the drive mechanism 7 and the tip of the back electrode needle 9 is pressed against the back surface of the wafer W, the needle tip is immersed into the needle container 8 against the coil spring 10. It's getting old.

Further, above the wafer support frame 5, a predetermined number of upper electrode needles 11 are arranged directly above the back electrode needles 9. These upper electrode needles 11 are fixed to a probe card 12 with resin or the like, and the probe card 12 is supported and fixed to a card support 12.

The prober configured as described above operates as follows to inspect and measure the pellet to be tested.

First, the wafer W is placed on the wafer support frame 5, and negative pressure is applied through the intake passage 5d and the intake hole 5e to attract and fix the wafer W.

When the suction and fixation is completed, actuate the drive mechanism 2,
The wafer support frame 5 is moved in the horizontal direction (X
-Y direction) to perform positioning. At this time, since the back electrode needles 9 are located below the wafer support frame 5, they do not become an obstacle to the movement of the wafer support frame 5.

When the positioning is completed, the drive mechanism 2 raises the wafer support frame 5 to bring the back electrode needles 9 into contact with the electrode layer on the back surface of the wafer W, and uses the wafer support frame 5 as a facing terminal and the back electrode needles 9 as a sensing terminal. Make Kelvin contact on the back side of the pellet to be tested. At this time, if the amount of rise is excessive, the wafer W will be lifted and the suction will be broken, and if the amount of rise is too small, the electrical connection between the electrode layer on the back surface of the wafer W and the back electrode needles 9 will be insufficient. but,
As described above, the back electrode needle 9 is movable in and out by the coil spring 10, so even if there is some error in the amount of rise, the above-mentioned inconvenience will not occur. However, for safety reasons, it is necessary to take advantage of the fact that the electrical resistance between the wafer support frame 5 and the back electrode needles 9 changes suddenly when they make contact, and apply feedback to the drive mechanism 2 to control the amount of increase. preferable.

When the back electrode needles 9 come into contact in this way, the drive mechanism 2 further raises the wafer support frame 5,
At the same time, the drive mechanism 7 is operated to raise the back electrode needle 9 while in contact with the back surface of the wafer W, and bring each electrode on the surface of the pellet to be tested into contact with the tip of the upper electrode needle 11. At this time, the contact pressure of the upper electrode needles 11 is applied to the wafer W, but since the wafer W is supported from below by the upper end of the needle container 8, there is no risk of large deformation or cracking.

In this way, when electrical contact is established between each electrode of the test pellet on the wafer W and the upper electrode needle 11, and between the electrode layer on the right back side of the test pellet and the lower electrode needle 9, the electrical contact of the test pellet is established. Start measuring characteristics.

As described above, when the wafer support frame 5 is used as the facing terminal and the back surface electrode needle 9 is used as the sensing terminal, when measurement is started by making Kelvin contact on the right back side of the pellet to be tested on the wafer W, the current flows across the wafer W during the measurement. Even if the current flows through the electrode layer on the back surface and the electrical resistance of the electrode layer is high, almost no voltage drop occurs. Therefore, even when measuring with a large current flowing through it, there is almost no possibility that an error will occur in the measurement. It goes without saying that the original effect of the Kelvin contact is that the contact resistance between the electrode layer on the back surface of the wafer W and the back electrode can be eliminated.

〔Effect of the invention〕

As is clear from the above description, the prober of the present invention makes a Kelvin contact with the surface directly behind the pellet to be tested on the wafer. By eliminating the resistance of the electrode layer on the back side, almost no voltage drop occurs, which has the effect of almost eliminating measurement errors and greatly improving the accuracy of inspection and measurement. This is extremely effective when inspecting and measuring the electrical characteristics of test pellets that use large currents for measurement, such as transistors.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a prober according to an embodiment of the present invention, Fig. 2 is a perspective view of a wafer support frame, Fig. 3 is an enlarged sectional view taken along the line - - of Fig. 2, and Fig. 4 is a back electrode needle. 5 is a block diagram of a conventional prober, and FIG. 6 is a plan view of a conventional chuck table of Kelvin contact type. 2, 7... Drive mechanism, 5... Wafer support frame, 8
... Needle container, 9 ... Back electrode needle, 11 ... Upper electrode needle, 12 ... Probe card, W ... Wafer.

Claims (1)

[Scope of utility model registration request] A wafer support frame that supports a wafer on which a large number of semiconductor pellets are formed is provided between a back electrode needle that can freely move up and down and an upper electrode needle that is placed directly above it, and that is movable in horizontal and vertical directions. A prober characterized in that the support frame is used as a facing terminal, the back electrode needle is used as a sensing terminal, and Kelvin contact is made on the right back side of a pellet to be tested on a wafer.