JPS58194348A - Automatic classification confirmation system for chip in wafer - Google Patents

Abstract

PURPOSE:To enable to confirm automatically that the chip in the wafer belongs to what class of the chip by a method wherein the transferred distance to transfer the specified pattern for chip name of the chip positioning directly under a probe to a pattern recognition region in the field of vision of a reader by manual operation is stored only in regard to the first wafer. CONSTITUTION:A joy stick is manually operated to transfer a wafer chuck table 5 as to put the chip ICM containing the specified pattern NK for chip name positioning directly under the probe to be in the field of vision of an image sensor ITV. When the chip ICM containing the specified pattern NK for chip name is put in the field of vision of the image sensor ITV, the transferred distance M1 of the wafer chuck table 5 up to the present position from the directly under part of the probe is detected to be stored in a memory unit MEM. Then the push button of a panel unit PANL is operated to show a frame the same or a little larger than the specified pattern NK for chip name shown on the picture at the specified position on the picture of a display. Then, the frame thereof is transferred as to put therein the specified pattern NK for the chip name. Then the transferred distance M2 thereof is written in the memory unit MEM.

Description

[Detailed description of the invention] This invention inspects wafers of semiconductors, ceramics, etc.

The present invention relates to an automatic type confirmation method for chips within a wafer, which enables automatic confirmation of the type of a positioned chip within a wafer during measurement, processing, etc.

In integrated circuit manufacturing, wafer probers are often used to repeatedly move and test chips in order to inspect the performance of semiconductor wafers that have undergone various processing steps.

In the wafer probing process, which is the final checking process for wafers, automatic loading/unloading of wafers is being promoted in order to increase the diameter of wafers, ensure reliable handling of the wafers, and save labor (automation).

In this configuration, wafers are sequentially transferred one by one from a cassette that can accommodate, for example, 25 wafers to the prealignment stage by a belt conveyor. and,
For example, a Bernoulli chunk is used to place the wafer on the wafer chuck table (measuring table) of a blobbing machine. On the other hand, the wafer whose measurement has been completed is conveyed from the wafer chuck table to an unloading position, and placed in a storage cassette by a belt conveyor. In addition, the probing machine converts an image signal from an image sensor such as an ITV into a digital bang signal, and by recognizing the digital bang signal, detects the dividing line (scribe line) that defines a chip or subchip. Automatically performs needle alignment for lining and tip.

However, for example, for wafers on which different types of chips are formed, as seen in the research prototyping process, the fully automatic wafer prober described above cannot distinguish the types of each chip. There is a drawback. Therefore, for example, if nine different types of chip iCs (subchips) indicated by dotted lines are arranged in each chip/knob group as indicated by solid lines as shown in FIG. , special consideration is required, such as measuring 3 subchips at intervals in the Y-axis direction.
The drawback was that such a task was difficult.

In addition, the inventors have formed on a single wafer a specific chip whose position on the wafer is specified and a plurality of chips whose relative positions with respect to this specific chip are determined (addresses are managed). , we are considering a method of performing various measurements on multiple chips whose addresses are managed and evaluating the entire wafer based on the measurement results, but the conventional fully automatic wafer blower mentioned above only performs alignment of the wafer chips. Since the purpose was to efficiently perform various measurements and test items for each chip type,
It was difficult to evaluate the entire wafer using the above method.

The present invention improves these conventional drawbacks, and
The purpose is to be able to automatically confirm what type of chip is in a wafer positioned at a predetermined processing position. Examples will be described in detail below.

FIG. 2 is a schematic plan view showing an example of the configuration of an automatic wafer prober that implements the method of the present invention. The automatic wafer blowbar l in this configuration example is composed of a blowing machine section 1a and a wafer transfer section 1b.

In this blowing machine section 1a, the wafer chuck table 5 (Ii feeder) is moved within a horizontal plane (X, Y directions) and rotated within a horizontal plane in the θ direction. This allows the relative position of the wafer to be arbitrarily changed with respect to the probe whose tips are arranged in correspondence with the measurement electrodes.

On the other hand, during measurement, with the wafer chuck table 5 pushed up, the probe and the electrode of the chip (ponding base) are electrically connected with a required contact pressure. Furthermore, for automatic positioning including alignment and chip type determination, a reading device, for example, an imaging device ITV, which magnifies and photographs the wafer surface is provided. and,
A display device (not shown) is provided that receives an imaging signal from the imaging device ITV and displays the enlarged image.

Further, a transfer arm (not shown) is attached to the blowing machine section 1a.

This transfer arm transfers the wafer transferred to the load stage 3 onto the Uchihachi medium pick table 5 which has been moved to the load position 5a.

On the other hand, the wafer whose measurement has been completed is transported to the unload position 4 after the wafer chuck table 5 moves to the unload position 5b.

The wafer transfer section 1b has four elevator mechanisms (saddles) 2a and 2b for installing cassettes containing wafers, and a pre-loading machine section 1a, which is equipped with the above-mentioned automatic wafer loading/unloading mechanism. Belt conveyors 6a and 5 connected to the loading position 3 and unloading position 4, which also function as alignment stages.
b, 7a and 7b.

Each operation of the fully automatic wafer prober having each of these functions is performed according to a control program of a control system configured as shown in FIG.

The microprocessor CPU controls each control unit connected via the signal path line BUS according to each control program as follows. Panel unit PANL
starts and stops the microprocessor CPU, inputs or instructs necessary precent information in each control program, inputs or instructs necessary precent information, and performs necessary display. It is also used to input a control signal for manual control of the stage control unit 5TGC.

The loader section control unit RODC is the elevator mechanism.

The receiver controls the belt conveyor and pre-alignment, and also controls the transfer arm and wafer chuck table 5.

The stage control unit 5TGC receives a pulse signal (one pulse corresponds to a predetermined movement amount with high precision) and drives a pulse motor,
Z stage control and θ stage control are performed according to each operation mode.

After the wafer is transported at the load position 5a, the wafer chuck table 5 is moved by a certain amount and stops at an imaging position 5c directly below the imaging device ITV.

The imaging signal from the imaging device ITV is sent to the A/D converter ADC.
is digitized and written to the storage device MEM. At this time, the portion of the wafer imaged by the image pickup device ITV is approximately l tm x l'w, although it is not particularly limited.

Next, this control system moves the wafer chuck table 5 to X or Y via the stage control unit 5TGC.
direction to detect the scribe line, and further rotate to adjust the direction of the scribe line so that it is parallel to the X-axis direction. When this is completed, the wafer chuck table 5 is moved in the X and Y directions so that the chip is correctly positioned directly under the probe without further rotating in the θ direction. In this way, the movement amount of the wafer chuck table 5 is detected by the known movement amount detection means, and the panel unit PA
It is written to the storage device MEM according to instructions from NL. With the above steps, the positioning of the wafer is completed. The second and subsequent wafers are automatically positioned based on stored information regarding the amount of movement of the wafer chuck table 5 necessary for positioning the first wafer. When the positioning is completed, the desired chips on the wafer and the inspection device TST are electrically connected via the probes, and various measurements and inspections are performed. The details of the positioning operation as described above are described, for example, in the attached specification of Japanese Patent Application No. 185952/1982, but it goes without saying that other positioning methods may be employed.

The procedure for reading the type (chip name) of the chip located directly below the probe is performed as follows.

(A) After completing the positioning, the chip-rich specific pattern can be placed within the reading area of the image pickup device ITV, which is spatially fixed from directly below the probe, by manually operating the first wafer and following the steps below. The wafer chuck table 5 and the like are moved to the position, and the amount of movement of the wafer chuck table 5 (the amount of movement of the stage) is detected and stored.

(1) First, manually operate the twister so that the chip ICM containing the chip-rich specific pattern NK located directly under the probe as shown in FIG. 4 falls within the field of view (display screen) of the imaging device ITV. Move the wafer chuck table 5. The chip-intensive specific button NK has an appropriate size, for example, 30 x 30 dots, and has a characteristic pattern so that the operator can distinguish it on the display screen. An embodiment of this chip-intensive specific button NK will be described in detail later.

(2) When the chip ICM containing the chip-heavy specific button NK is placed within the field of view of the imaging device ITV, the amount of movement M1 of the wafer chuck table 5 from directly below the probe to the current position is detected and stored in the storage device MEM. .

(3) Next, operate the push button on the panel unit PANL,
A frame (reading area) that is the same as or somewhat thicker than the chip-intensive specific pattern NK on the screen is displayed at a specific position on the display screen. ((4) Next, move the frame so that the chip-intensive specific pattern NK fits within it.Then, write the amount of movement M2 into the storage device MEM.

(5) When the above operations are completed, the tip CM is moved directly below the probe again based on the movement amount Ml stored in the child II (2).

Note that the operations described so far only need to be performed immediately after the positioning of the first wafer is completed. After this, wafer measurement and evaluation will begin.

(B) Next, the procedure for reading the type of chip located directly below the probe will be described.

(6) When a chip name reading command is output from the host computer of the measurement system in response to an instruction from the operator, this device reads the movement amount M1 in step (2) above from the storage device MEM, and controls the stage by that amount. The wafer chuck table 5 is automatically moved C: directly below the imaging device ITV via the unit 5TGC.

(7) Next, after exposing the frame (reading area), read the movement amount M2 in the above step (4) from the storage device MEM again, move the frame by that amount, and press the chip-heavy specific button N.
Consider K within that framework.

(8) Next, the pattern within this frame is converted into an image signal by the image pickup device ITV, and then written to the storage device MEM as bright and dark binary chip name information via the A/D converter ADC.

(9) Next, the chip type is recognized based on the combination of brightness and darkness at a location corresponding to a predetermined location within this frame. This is done based on chip type discrimination data stored in advance.

(10) Finally, the wafer is returned to its original position.

FIG. 5 is a diagram illustrating an example of a specific pattern for indicating chip type. The same figure (A) is a comb-shaped pattern, the same figure (B)
indicates a dot array type button, and the dotted line indicates the imaging area partitioned by the small frame.

The shaded area is the area where an imaging signal with high brightness Φ is generated. This pattern is divided into two areas 41 by a dividing line 100. Area A is chip type tUa
The part constituting the signal for use, the opening, is the alignment mark part for the small frame of -G. That is, the mouth part specifies the chip type reading area. Although the dot array type button shown in FIG. 2B has mouth portions provided at both ends, the mouth portions may be provided at only one of the ends. In this embodiment, region A is further divided into five parts so that combinations of brightness and darkness can be created.

In FIG. 5, these divided areas are labeled 81 to B5, respectively.

FIG. 6 is a diagram showing the configuration of 26 types of chip-intensive specific patterns based on combinations of these divided areas, that is, combinations of brightness and darkness. According to this figure, the pattern in FIG. 5 indicates chip type (■).

In addition, when the operator instructs chip type discrimination, if the pattern cannot be placed within the frame only by the movement amount M2 of the frame in step (7) above, the opening of the pattern in FIG. Adjust the position of the frame or sea urchin so that it is within the frame (so that the chip-intensive specific button is included in the reading area).

To do this, it is sufficient to move the frame in a direction where all the imaging signals of the mouth area become bright. At this time, it is extremely effective to set a certain threshold value for the frame position adjustment amount. For example, the amount by which the probe deviates from the pad portion can be used as the threshold value.

Above, we have described an automatic chip type confirmation method that displays a frame that is the same as or slightly thicker than the chip-rich specific pattern NK on the screen. A recognition area that should be set as appropriate as possible,
The shape of the region may be arbitrary. In addition, the reading part of the brightness necessary for recognizing the chip type mentioned in step (9) above can be obtained by reading the necessary brightness information for each area in the defined area of each divided area B1 to BS in part A of Fig. 5. Enough. Therefore, the recognition area for obtaining the information necessary for recognizing the chip type can be created by, for example, making the width of the above frame extremely small (in the minimum case, one scanning line for reading).
It can also be set so that it passes through each of the above definition areas.

The chip-frequent use specific button can be easily defined using characters such as alphabento or a symbol indicating a product name. Furthermore, specific to the chip i
It is also possible to easily define and use a part of a circuit or element pattern. In these cases, it is necessary to perform pattern recognition with a two-dimensional spread, rather than simply reading the combination information of brightness and darkness as described above. Therefore, the chip-frequently used specific pattern may be stored in advance as chip type discrimination data, and the chip type may be confirmed by matching the stored pattern with the currently recognized pattern.

Furthermore, in the movement amount setting procedure described above, the movement amount when the table 5 is manually moved so that the specific pattern provided on the chip at the processing position is included in the reading area of the imaging device is memorized, and the movement of the frame is It is also possible to omit the configuration. In addition, if the relative positional relationship from the initially positioned wafer installation location to the location of the device that reads part or all of the chip-intensive specific pattern set for the chips at that location is known in advance, the value It is sufficient to store this in the memory using the movement amount setting means.

As explained above, in the present invention, it is possible to memorize the amount of movement of the chip-rich specific pattern of the chip located directly under the probe into the pattern recognition area within the field of view of the imaging device ITV by manual operation only for the first wafer. For example, the name of the chip directly under the probe can be confirmed at any time after that, so it is possible to identify chips with different types of elements and circuits, such as wafers in the research or development stage, or completed wafers containing different ICs. Even if the wafer is made up of
Wafer evaluation can be performed efficiently.

In other words, by registering the necessary test program names in advance according to the test items determined for each chip type, the advantage is that by checking the chip type, these programs can be scheduled in an orderly manner and various measurements can be performed automatically. be.

In addition, it is necessary for the probe to be in proper contact with the pad for measurement, but for example, if the blower malfunctions due to external noise and shifts by one chip, or if the probe comes off the pad. can also be dealt with. This means that when automatically probing multiple wafers without human intervention, it is possible to interrupt the test to avoid collecting invalid data, and to prevent electrical damage to devices. There are special effects such as

[Brief explanation of the drawing]

FIG. 1 is a chip baton diagram showing an example of a research wafer, FIG. A block diagram showing one embodiment, FIG. 4 is a tip baton diagram for explaining the blowbar operation, FIG. 5 is a line diagram showing an example of a chip-intensive use specification pattern, and FIG. 6 is a tip-heavy use specification shown in FIG. 5. FIG. 6 is a diagram illustrating classification based on the difference in the shape of a pattern. 1 is an automatic wafer follower, 1a is a blowing machine section, 1b is a wafer transfer section, 2a and 2b are elevator mechanisms, 3 is a loading position, 4 is an unloading position, 5 is a wafer chuck table, 5a is a loading position, 5b is a Unloading position, 5C is shooting position, 6a, 6b
, 7a, 7b are belt conveyors, ITV is an imaging device, C
PU is a microprocessor, PANL is a panel uni-7
5TGC is stage control knee 3-soto, RODC is loader control unit, MEM is storage device, ADC is A
/D converter, Ilo is input/output interface, TST
1 is an inspection device, a PC is a probe card, 100 is a dividing line for explaining the role of the button, 1 is a button type definition area, and 1 is an area for aligning the small frame for identifying the button type UL. Patent Applicant Nippon Telegraph and Telephone Public Corporation Patent Attorney Gobe Tamamushi (3 others)

Claims (1)

[Claims] (1) A wafer having a plurality of chips arranged thereon is moved by a carrier and the chips are positioned at predetermined processing positions, and the wafers that have undergone predetermined processing are moved and stored. In an automatic type confirmation method for chips in a wafer in an automatic wafer processing apparatus, each chip in the wafer is provided with a specific pattern for chip winter indicating the chip type;
A spatially fixed reading device for reading part or all of the chip-heavy use specific pattern, and a chip winter specific pattern provided on the chip at the processing position necessary for including the chip winter specific pattern within the reading area of the reading device. a movement amount setting means for storing a movement amount in a memory; and a movement amount setting means for storing a movement amount in a memory so that a chip-heavy use specific button of a chip in the processing position is included in a reading area of the reading device when a chip name reading command is issued. a button positioning means for moving at least the conveyor based on the amount of movement made; and a button recognition means for storing data for determining the type of the chip winter specific pattern, and after positioning by the button positioning means, An automatic type confirmation method for chips in a wafer, characterized in that the reading device reads the chip-frequently-used specific button, and the type of the chip is determined by the button recognition means from the read button information. (2. In the automatic type confirmation method for chips in a wafer as set forth in claim 1, the movement amount setting means may be configured to be a specific button for CH/knob name provided on the chip at the processing position or a button on the reading device. An automatic type confirmation method for chips in a wafer, characterized in that the method includes a movement amount detection means for detecting a movement amount when the carrier is manually moved until it is included in a reading area. (3) Patent Claims In the automatic type confirmation method for chips in a wafer according to scope 1, the movement amount setting means moves the movement amount until a specific button for chip name provided on the chip at the processing position is included in the field of view of the reading device. first movement amount detection means for detecting the amount of movement when the device is moved by manual operation; 1. A method for automatically confirming the type of chips in a wafer, comprising: second movement amount detection means for detecting the amount of movement when a part or all of a chip-intensive specific pattern is moved to a position included therein. (4) In the automatic type confirmation method for chips in a wafer as set forth in claim 3, the button positioning means:
When the reading area is moved from the specific position based on the movement amount stored in the memory, if a positional shift occurs between the reading area and the chip winter specific button, the reading area is moved. 1. A method for automatically confirming the type of chips in a wafer, comprising a position adjusting means for adjusting the position of the reading area or the carrier within a predetermined permissible limit so that the chip winter specific button is included in the chip winter specific button.