JPH04305950A - Measuring method for semiconductor wafer - Google Patents

Abstract

PURPOSE:To recognize accurately the shape of a semiconductor chip near the circumference of a semiconductor wafer by detecting the center and radius of the semiconductor wafer and the array position of said semiconductor chip as well. CONSTITUTION:Image data with no semiconductor wafer 2 is stored as reference data. The reference data and the image data about the circumference of the semiconductor wafer 2 are compared and computed in a CPU 9 so as to detect the center and radius of the semiconductor wafer 2. The image data of the semiconductor chip and the image data of one semiconductor chip previously stored is calculated and processed at the CPU 9 so as to detect the array position of the semiconductor chips. A further attempt is made to improve the inspection efficiency and reliability of the semiconductor wafer by detecting the center and radius of the semiconductor wafer and accurately recognizing the shape of the semiconductor chips near the circumference of the semiconductor wafer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a semiconductor wafer, and more particularly to a method for measuring a semiconductor wafer for recognizing the shape of a semiconductor chip near the circumference of the semiconductor wafer.

0002

[Prior Art] Generally, a prober that inspects the electrical characteristics of a semiconductor chip (hereinafter referred to as a chip) formed on a semiconductor wafer (hereinafter referred to as a wafer) is movable in horizontal and vertical three-dimensional directions. After aligning the wafer placed on the wafer mounting table, a probe card with probe needles (measurement probes) implanted in positions corresponding to the electrodes of the chips arranged regularly on the wafer is placed. The probe is attached to the probe head of a prober, and the probe needle is brought into contact with each electrode of the chip to sequentially perform electrical testing on each chip.

In order to efficiently inspect a wafer in such a wafer inspection process using a prober, it is necessary to eliminate wasteful inspection of defective chips that are not perfectly shaped and exist near the circumference of the wafer. Therefore, it is extremely important for inspection efficiency to perform measurements such as alignment of the wafer a and alignment of the probe card and the chip with high precision.

[0004] Conventionally, therefore, as a method for measuring chips formed on the surface of a wafer, for example, Japanese Patent Laid-Open No.
Those described in Japanese Patent No. 42137 and the like have been developed. In these conventional measurement methods, the center of the wafer mounting table is determined using a capacitive sensor installed in a direction facing the upper surface of the wafer mounting table.

That is, by moving the wafer mounting table under the capacitive sensor, and noting that there is a difference in the output of the capacitive sensor between the top surface of the wafer mounting table and a position off the top surface, Detect three or more edges of the wafer and determine the center coordinates of the wafer mounting table under the capacitive sensor. Next, move the mark placed in advance on the center of the wafer mounting table under the TV camera installed for wafer pattern recognition, match it with the mark placed on the TV screen in advance, and place the mark on the TV screen under the TV camera. Find the center coordinates of the wafer mounting table at the position where the mark is displayed. In addition, capacitive sensors and T
Measure and record the distance from the position where the mark is displayed on the TV screen under the V camera.

Next, the wafer was mounted on a wafer mounting table, and the wafer mounting table was moved under the capacitive sensor, noting that there was a difference in the output of the capacitive sensor between the wafer surface and the outside of the wafer surface. Detects three or more edges on the wafer circumference,
Find the wafer center and wafer radius. In addition, the amount of deviation between the center of the wafer mounting table and the center of the wafer in the X-axis direction and the Y-axis direction is calculated and determined.

Next, the wafer mounting table is moved under the TV camera, and the -point of the chip on the wafer, for example, the upper left corner of the chip, is aligned with the mark on the TV screen. At this point, the mutual coordinate relationship between the center of the wafer, the radius of the wafer, and the -point on the chip at the position where the mark will be displayed on the TV screen below the TV camera has been determined, and it has been input into the prober as a parameter in advance. By performing calculations using the length in the X direction and the length in the Y direction of the chip, the area of the chip near the circumference of the wafer can also be determined, and defective chips with imperfect shapes can be known before inspection.

[0008]

[Problems to be Solved by the Invention] However, in the conventional method for measuring semiconductor wafers, it is necessary for the operator to match the mark on the TV screen with the mark placed at the center of the wafer mounting table. The mark placed at the center of the wafer did not necessarily match the center of the wafer mounting table as measured by the capacitive sensor. For this reason,
An error may occur in the mutual relationship between the center position of the wafer under the TV camera and the position of the chip. This error is
As a result, even if the operator knew that the area of the chip near the circumference of the wafer was different from the actual one, it was impossible to correct it because he could not tell in which direction and by how much the center of the wafer had shifted.

For this reason, a defective chip that is originally not in perfect shape may be recognized as a chip to be inspected that is in perfect shape, or conversely, a chip that is in perfect shape may be recognized as a chip that is not in perfect shape. . Therefore, in subsequent wafer inspections, the probe needles of the probe card may not be able to accurately contact the electrodes of all the chips to be inspected, or conversely may come into contact with chips that are not in perfect shape and are not being inspected, resulting in poor inspection efficiency. This not only causes a decrease in the reliability of the test, but also reduces the reliability of the test, and furthermore, there are problems such as a decrease in the life of the probe needle.

[0010] Furthermore, in the dicing process in which chips formed on a wafer are cut with a grindstone, there is a similar problem in that the presence of defective chips lowers the cutting efficiency.

The present invention was made in view of the above circumstances, and aims to improve wafer inspection efficiency and reliability by accurately recognizing the shape of chips near the circumference of a wafer through simple operations. The purpose of this paper is to provide a method for measuring semiconductor wafers.

0012

[Means for Solving the Problems] In order to achieve the above object, a first semiconductor wafer measuring method of the present invention detects the shape of a semiconductor wafer, and detects the shape of a large number of regularly arranged semiconductor wafers on the semiconductor wafer. In detecting the arrangement position of the semiconductor chips and recognizing the shape of the semiconductor chips on the semiconductor wafer, image data of the wafer mounting table before mounting the semiconductor wafer is stored as reference data, and the image data is used as reference data. This method is characterized in that the center and radius of the semiconductor wafer are detected by comparing the image data of the wafer mounting table on which the semiconductor wafer is placed. Further, in the second semiconductor wafer measurement method of the present invention, in the first semiconductor wafer measurement method, vertical and horizontal image data of adjacent semiconductor chips on the semiconductor wafer is detected, and the arrangement position of the semiconductor chips is detected. It is characterized by:

In the present invention, the image data comparison calculation means compares and calculates the image data of the wafer mounting table before placing the semiconductor wafer, that is, the reference data, and the image data of the wafer mounting table after placing the semiconductor wafer. Any device may be used as long as it can be used. For example, a signal captured by a CCD camera can be subjected to comparative calculation processing by a central processing unit (CPU).

In order to detect the center and radius of the semiconductor wafer, the above reference data and the image data of the mounting table after the semiconductor wafer is placed are compared with the reference data at at least three points on the circumference of the semiconductor wafer. All that is required is a comparison, and by comparing these three points, the center and radius of the semiconductor wafer can be detected. In this case, as the reference data, for example, the image data of the wafer mounting table may be used as is, or special image data may be obtained by adding a pattern to the wafer mounting table so as to facilitate image data comparison calculations. In addition, to detect the array position of semiconductor chips, image data of the semiconductor wafer placed on the mounting table is displayed on an image display device, the operator is instructed to specify the range of one semiconductor chip, and the image data is stored as reference data. The image data of the semiconductor wafer that is recorded in the apparatus and then placed on the wafer mounting table is compared with the reference data, and the position can be detected based on the position of the matching image data.

[0015]

[Operation] According to the method for measuring a semiconductor wafer of the present invention configured as described above, image data without a semiconductor wafer is stored as reference data, and this reference data is compared with image data of a semiconductor wafer. Accordingly, the center and radius of the semiconductor wafer can be detected, and the shape of the semiconductor wafer can be recognized.

Furthermore, by comparing the image data of the semiconductor chips with pre-stored semiconductor chip pattern data, the arrangement position of the semiconductor chips can be detected.

Therefore, the shape of the semiconductor chips near the circumference of the semiconductor wafer can be easily recognized by detecting the center and radius of the semiconductor wafer and the arrangement position of the semiconductor chips.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a schematic configuration diagram of a prober that uses the semiconductor wafer measuring method of the present invention.

This prober includes a wafer mounting table 3 that vacuum-chucks a semiconductor wafer 2 to be measured (hereinafter referred to as a wafer) transported by a wafer transporting device 1, and a wafer mounting table 3 that is arranged horizontally and vertically in three dimensions. a wafer mounting table driving device 4 that moves in the direction; a probe card 5 that is disposed above the wafer mounting table 3 and inspects the electrical characteristics of a semiconductor chip (hereinafter referred to as a chip) formed on the wafer 2;
CC that detects the circumference of wafer 2, center position of chips, etc.
It is composed of a D camera 7 and a control section 8 that controls and processes detection signals from the CCD camera 7.

The control unit 8 compares and calculates the detection signal from the CCD camera 7 with pre-stored parameters necessary for measurement (for example, chip pattern data, movement amount data, wafer center data, etc.), and controls the wafer transfer device 1. and a CPU 9 that transmits a control signal to the wafer mounting table driving device 4;
The image display device 10 displays the detection signal from the CCD camera 7 as image information via the PU 9.

[0022] The probe card 5 has probe needles 5a implanted therein corresponding to the electrode positions of the chip.

Next, a method for measuring a semiconductor wafer according to the present invention will be explained.

◎Detection of radius and radius of wafer First, move the wafer mounting table 3 and place the CC on the circumference of the wafer mounting table 3.
Position D camera 7. Then, the signal captured by the CCD camera 7 is taken into the CPU 9, and the wafer mounting table 3
As reference data 11, image data near the circumference 3a of
It is stored in the memory storage device 18 of the CPU 9 (see FIG. 2).

Next, the wafer 2 is transferred from a cassette (not shown) containing a plurality of wafers 2 manufactured by printing a pattern at once and having chips 2a and 2b formed on the entire surface thereof to a wafer mounting table by the transfer device 1. After being placed on 3, CC
The vicinity of the circumference 3a of the wafer mounting table 3 is imaged by the D camera 7, and the signal thereof is recognized as image data 12 by the CPU 9 (see FIG. 3).

Then, the reference data 11 and the image data 12 after mounting the wafer 2 are compared and calculated in the CPU 9 to obtain the curvature of the circumference of the wafer 2, and this curvature is combined with the center point O and the radius r of the wafer 2. The shape (size,
area, etc.) is detected. In this case, as shown in FIG. 2 and FIG.
1 and the image data 12, the center O and radius r of the wafer 2 are determined.

◎Detection of chip arrangement position After determining the center of the wafer as described above, the image display device 10 displays the chip 2a on the wafer 2, the length in the X direction and the length in the Y direction of the chip 2a, which have been input into the CPU 9 as parameters in advance. Considering the length in the direction and the magnification of the CCD camera 7, a frame 19 having the same shape as the chip 2a is displayed (see FIG. 4). Operator is CPU
The frame 19 is aligned with the chip 2a using a mouse or a joystick (not shown) connected to the CPU 9 (see FIG. 5), and the CPU 9 is notified by means such as a switch (not shown) connected to the CPU 9. Then, the CPU 9 stores the image data 20 in the frame 19 as reference data for one chip 2a in the memory storage device 18, and at the same time calculates the already calculated circumference of the wafer 2 and the arrangement position of the chip 2a. .

Regarding the second and subsequent wafers, the image data 20 stored as reference data and the image data of the wafer 2 are compared in the memory storage device 18, and by detecting a matching location, the image data 20 and the image data of the wafer 2 are compared without operator intervention. The arrangement of chips 2a within wafer 2 can be determined.

Therefore, defective chips 2b with imperfect shapes existing near the circumference of the wafer 2 and chips 2a with other accurate shapes can be accurately discriminated, and the wafer inspection by the probe card 5 can be efficiently performed. It is possible to perform the test well, improve the reliability of the test, and furthermore, since the probe needle 5a does not come into contact with the defective chip 2b,
Wear of the probe needle 5a can be reduced, and the life of the probe needle 5a can be increased.

In the measurement of the second and subsequent wafers 2,
If the measurement data of the first wafer 2 is stored in the CPU 9, the measurement of the wafer 2 can be easily performed.

In the above embodiment, the reference data 11, image data 12, etc. are detected using the CCD camera 7. However, it is not always necessary to detect the data using the CCD camera 7. By scanning the optical means, reference data 11 and image data 12 are obtained.
etc. may be detected.

Furthermore, in the above embodiment, the measurement of the wafer in the wafer inspection process using a prober was explained.
The present invention is not limited to the above embodiment, and can be similarly used in a dicing process in which the chips 2a formed on the wafer 2 are cut with a grindstone.

[0033]

As explained above, according to the semiconductor wafer measuring method of the present invention, the shape of the semiconductor wafer can be easily detected by detecting the center and radius of the semiconductor wafer, and the arrangement position of semiconductor chips can be easily detected. can be easily detected, so the shape of the semiconductor chip near the circumference of the semiconductor wafer can be recognized. Therefore, it is possible to eliminate wasteful testing of defective semiconductor chips, improve the efficiency of testing semiconductor wafers, and improve the reliability of testing.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a prober using the semiconductor wafer measuring method of the present invention.

FIG. 2 is an explanatory diagram showing reference data in the present invention.

FIG. 3 is an explanatory diagram showing one point of image data in the present invention.

FIG. 4 is an explanatory diagram of a frame displayed on an image display device to indicate a chip position.

FIG. 5 is an enlarged plan view of a semiconductor wafer showing a detection state of semiconductor chips in the present invention.

FIG. 6 is an explanatory diagram of a semiconductor wafer.

[Explanation of symbols]

2 Semiconductor wafer 2a Semiconductor chip 2b Defective chip 2c Circumference of semiconductor chip 3 Wafer mounting table 3a Circumference of wafer mounting table 9 CPU (Central Processing Unit) 10 Image display device 11 Standard data 12 Image data 19 Frame with the same shape as the chip

Claims (2)

[Claims] 1. In recognizing the shape of the semiconductor chips on the semiconductor wafer by detecting the shape of the semiconductor wafer and also detecting the arrangement positions of a large number of semiconductor chips regularly arranged on the semiconductor wafer, The image data of the wafer mounting table before placing the semiconductor wafer is stored as reference data, and the center and radius of the semiconductor wafer are determined by comparing the above reference data with the image data of the wafer placing table after placing the semiconductor wafer. A semiconductor wafer measuring method characterized by detecting. 2. The method for measuring a semiconductor wafer according to claim 1, wherein vertical and horizontal image data of adjacent semiconductor chips on the semiconductor wafer are detected to detect the arrangement position of the semiconductor chips. How to measure.