JPS6314447A - Microscope for wafer prober - Google Patents

Abstract

PURPOSE:To facilitate the inspecting work of a wafer prober itself by a method wherein the title microscope is provided with the first optical system to from an enlarged image of a chip in contact with a pointer of wafer prober, displaying means to display the wafer inspection results and the second optical system to display the images of said displaying means together with the enlarged image of chip. CONSTITUTION:The title microscope is provided with the first optical system 2 to form an enlarged image of a chip in contact with a pointer 17 of a wafer prober on a wafer W loaded on the wafer prober displaying means 14a-14c optically displaying the wafer inspection results of wafer prober and the second optical system 7 displaying the images of said displaying means 14a-14c together with the enlarged image of chip through the intermediary of a beam splitter 4 (halfmirror) provided on the first optical system 2. Said displaying means 14a-14c are fitted with a transparent displayers 15a-15c with letters PASS, FAIL, SENSOR respectively written e.g. in a notch part 12a of a displaying plate 12 while LED 13a-13c are respectively arranged backside to light the LED corresponding to the measured results by a measuring circuit 16.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an improvement in a microscope attached to a wafer prober.

(B) Conventional Technology On a wafer that has been processed by a wafer prober, semiconductor devices such as ICs are arranged in a mesh-like chip structure.

These chips on the wafer include defective chips caused by various causes. Therefore, defective chips are selected by inspecting the electrical characteristics of each chip.

The wafer prober used to inspect this wafer (wafer probing) has a needle that contacts the chips on the wafer, a measurement circuit to which this needle is connected, and a marking of defective chips based on the measurement results of this measurement circuit. A device is known that is equipped with a marking means for marking a wafer and a wafer drive mechanism that moves the wafer up and down and moves it chip by chip.

This wafer prober is equipped with an optical microscope for checking the state of contact between the chip and the needle. This conventional microscope for a wafer prober has a configuration substantially similar to that of a general optical microscope, and includes an objective lens, an eyepiece lens, a lens barrel, and the like.

(c) Problems to be solved by the invention - As the wafer prober continues to inspect wafers, abnormalities occur in the needle or measurement circuit, leading to problems with the quality of the chips.

Errors occur due to incorrect selection of defects. Therefore, it is necessary to inspect the wafer prober itself. This test is
This is done according to the following steps:

First, load the reference wafer into the wafer prober. This reference wafer is one of the wafers that was previously inspected by the wafer prober and has been saved, and defective chips are marked.

Next, the needle is brought into contact with the chips on this reference wafer one after another, and the electrical characteristics of the chips are measured.

At this time, the operator looks through the conventional wafer prober microscope and confirms whether a defective mark is attached to the chip. Next, the operator confirms the measurement results displayed on the operation section of the wafer prober.

If the measurement result is bad even though there is no defect mark on the chip, or if the measurement result is good even though there is a defect mark on the chip, check the measurement circuit of the wafer prober, etc. This means that an abnormality has occurred.

However, in the above-mentioned wafer prober inspection, the operator must alternately look at the wafer prober RA mirror and the wafer prober operating section, which is inconvenient and takes time. Ta.

The object of the present invention is to provide a microscope for a wafer prober, which overcomes the above-mentioned disadvantages and facilitates the inspection work of the wafer prober itself.

(d) Means for Solving the Problems As a means for solving the above-mentioned disadvantages, the microscope for wafer prober of the present invention has a chip on a wafer loaded in a wafer prober, in which the needle of the wafer prober comes into contact with the microscope. a first optical system that obtains an enlarged image of the chip being inspected; a display unit that optically displays the wafer inspection results of the wafer prober; and a display unit that displays the display unit via a beam splitter provided in the first optical system. and a second optical system that displays an image of the chip along with an enlarged image of the chip.

(E) Function The wafer prober microscope of the present invention displays the measurement results of the chip as well as the enlarged image of the chip, so the operator only has to look through the microscope.

Therefore, the inspection work of the wafer prober itself is facilitated and the time required for inspection is shortened.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a diagram showing an optical system of a wafer prober microscope (hereinafter simply referred to as a microscope) 1 according to an embodiment of the present invention.

The microscope 1 includes a first optical system 2 and a second optical system 7. The first optical system 2 includes an objective lens 3, a half mirror (beam splitter) 4, an eyepiece lens 5, and a lens barrel 6.

The objective lens 3 is supported by the lower end of the lens barrel 6 and captures an image of the chip t on the wafer W loaded in the wafer prober (see FIG. 3). The light beam from the objective lens 3 travels upward inside the lens barrel 6 and passes through the half mirror 4 (see Figure 1).
. The light beam transmitted through the half mirror 4 further reaches the eyepiece lens 5. The operator can see an enlarged image of the chip t by looking through the eyepiece 5 with the naked eye e.

The second optical system 7 includes a shutter 8, a lens 9, a display plate 12, and a lens barrel 11.

The lens barrel 11 is provided in the lens barrel 6, and its left end portion 11a communicates with the housing portion 6a of the half mirror 4 of the lens barrel 6.

A display plate 12 is provided at the right end portion 11b of the lens barrel 11. The display board 12 has display parts (display means) 14a, 1 illuminated from the front and back by light emitting diode elements (LEDs) 13a, 13b, 13C.
4b, 14C (in Figure 1, LED
13b, only the display section 14b is shown).

The display parts 14a, 14b, 14C are the display board 12
A colorless transparent or colored transparent display plate 15 is placed in the notch 12a of the
A, 15b, and 15c are attached. Display board 15
a, 15b, and 15c, respectively r P A S S
J r F A I L J r S E N
The characters "SOR" are marked, and these characters indicate the meaning of the lights on the display sections 14a, 14b, and 14C.

Behind the display boards 15a, 15b, 15c are the LEDs.
13a, 13b, and 13c are located respectively. L.E.
D13a, 13b, and 13c are connected to the measurement circuit 16 of the wafer blower, and the LEDs are turned on according to the measurement result of the measurement circuit 16. LED13a, 1
The light from 3b, 13c is transmitted to the display boards 15a, 15b, 15
By passing through the display parts 14a, 14b, 14
C is illuminated.

The light from the display sections 14a, 14b, and 14c travels to the left inside the lens barrel 11 and passes through the lens 9 (see FIG. 1). The light transmitted through the lens 9 is reflected by the half mirror 4, travels upward in the lens barrel 6, and enters the eyepiece 5. thus,
Along with the enlarged image of the wafer, display sections 14a, 14b, 14c
image is displayed (see Figure 3). Note that the shutter 8 is used to close the display sections 14a and 14b except when inspecting the wafer prober.
, 14C so that the images of the displays 14a and 14b are not visible.
, 14c.

The wafer W is supported on a wafer drive mechanism (not shown) within the wafer processor. This wafer drive mechanism has a function of moving the wafer W within a horizontal plane in order to sequentially position the chips on the wafer W directly under the objective lens 3. The wafer drive mechanism also has the function of moving the wafer W up and down and bringing the tip t into contact with the tips of the needles 17, . . . , 17.

The needles 17, . . . , 17 are located below the eyepiece 3 and the wafer W.
It is supported by a ring 18 that is horizontally supported and fixed between. The needles 17, . . . , 17 are each connected to a deflection measuring circuit 16.

Next, an example of how this microscope 1 is used will be explained below.

When it is thought that an abnormality has occurred in the wafer prober, load the reference wafer W into the wafer prober,
Open shutter 8.

Next, each chip t of the wafer W is moved by the wafer drive mechanism.
are sequentially moved below the objective lens 3, and the needles 17, .
..., 17 are brought into contact. During this time, the worker is looking into the eyepiece 5. The image that appears to the worker's naked eye is the third image.
(The shaded area in FIG. 3 indicates that the area is dark).

When the needles 17, .
Turn on D 13 C. When the LED 13C is turned on, the display section 14c lights up and is displayed together with the enlarged image I of the chip t (see FIG. 3). Depending on the presence or absence of the display on the display section 14c, the operator can adjust the needles 17, . . . while looking through the eyepiece 5.
..., it is possible to check whether or not there is an abnormality in 17.

When the needles 17, . . . , 17 completely contact the tip t and the display section 14C is displayed, the measuring circuit 16 measures the electrical characteristics of the tip t. If the measurement result is "good", the LED 13a is turned on and the display section 14a is displayed. On the other hand, if the measurement result is "defective", the LED 13b is turned on and the display section 14b is displayed.

A defective mark m is marked on a defective chip t on the reference wafer W. When the chip t marked with the defective mark n is measured, the display section 14b is displayed (the third
(see figure), and if the display section 14a is displayed when measuring the chip t on which no defective mark n is marked, it means that there is no abnormality in the measuring circuit 16.

Conversely, if the display section 142 displays when a chip t with a defective mark m is measured, or if the display section 14b displays when a chip t without a defective mark m is measured, This means that an abnormality has occurred in the measurement circuit 16.

While removing the eyepiece 5, the operator checks each chip for the presence or absence of the defective mark m on the chip and the display on the display sections 14a and 14b. If erroneous displays on the display sections 14a and 14b occur frequently, readjustment or repair of the measurement circuit 16 is performed.

When the wafer prober is in normal wafer inspection state,
The shutter 8 of the microscope 1 is closed and functions as a conventional wafer prober microscope.

In the above embodiment, both the first optical system and the second optical system have the simplest configuration, and a half mirror is shown as the beam splitter, but the invention is not limited to these, and may be used as appropriate. Design changes are possible.

Further, in the above embodiment, a transparent display plate illuminated from behind is used as the display means, but the display is not limited to this, and the design can be changed as appropriate.

(G) Effects of the Invention The wafer prober microscope of the present invention includes a first optical system that obtains an enlarged image of a chip on a wafer loaded in a wafer prober and in contact with a needle of the wafer prober. , a display means for optically displaying a wafer inspection result of the wafer prober, and a second optical system for displaying an image of the display means together with an enlarged image of the chip via a beam splitter provided in the first optical system. Since the wafer prober is equipped with a system, it has the advantage that the inspection work of the wafer prober itself can be carried out easily and in a short time.

[Brief explanation of drawings]

Each of the drawings shows an embodiment of the present invention; FIG. 1 shows an optical system of a wafer prober microscope according to the same embodiment, and FIG. 2 shows a display plate of the same wafer prober microscope. The front view and FIG. 3 are diagrams showing an enlarged image of a chip on a wafer and an image of a display section obtained by the same wafer prober microscope. 2: first optical system, 4: half mirror, 7: second optical system, 14a14b/14c: display section, W: wafer, t: chip. Patent applicant ROHM Co., Ltd. agent
Patent Attorney Shigeru Nakamura Figure 3

Claims (1)

[Claims] (1) A first optical system that obtains an enlarged image of the chip on the wafer loaded in the wafer prober and that is in contact with the needle of the wafer prober, and optically displays the wafer inspection results of the wafer prober. and a second optical system that displays an image of the display means together with an enlarged image of the chip via a beam splitter provided in the first optical system.