JPH043107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an in-wafer chip that automatically confirms the type of a positioned chip in a wafer when inspecting, measuring, processing, etc. a semiconductor, ceramic, etc. wafer. This invention relates to an automatic type confirmation device.

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 chipping 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. The wafer is then placed on the wafer chuck table (measuring table) of the probing machine using, for example, a Verneuil chuck. On the other hand, the wafers for which the measurement has been completed are transported from the wafer chuck table to the unloading position and placed in a storage cassette by a belt conveyor. In addition, probing machines convert the imaging signal from an image sensor such as an ITV into a digital pattern signal, and by recognizing this pattern, detect the dividing line (scribe line) that defines a chip or subchip. Automatically performs alignment and needle alignment to the tip.

However, for wafers on which different types of chips are formed, such as wafers for research prototyping, the fully automatic wafer prober described above has the disadvantage that it is not possible to discern the type of each chip. . Therefore, for example, if nine different types of chip ICs (subchips) indicated by dotted lines are arranged in each chip group as indicated by solid lines as shown in FIG. 1, X, This method requires special consideration, such as measuring three subchips at intervals in the Y-axis direction, but it has the disadvantage that it is difficult to do so.

In addition, the present inventors formed on a single wafer a specific chip whose position on the wafer is specified and a plurality of chips whose relative positions 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 prober mentioned above is only used to align the wafer chips. Because it was hot,
It has been difficult to efficiently carry out various measurements and test items corresponding to each chip type and to evaluate the entire wafer using the above method.

The present invention improves these conventional drawbacks, and its purpose is to automatically confirm what type of chip is in a wafer positioned at a predetermined processing position. There is a particular thing.

In order to achieve the above object, the present invention has the following configuration. That is, in the probing machine section, a chip inspection section using a probe and a reading section for determining the chip type are placed side by side, and after moving the wafer chuck table at the position of the chip inspection section and aligning the probe with the electrode of the chip, In this state, the movement distance M1 from the fixed wafer position (specific position) to the chip type determination reading unit is detected, and the reading area frame exposed by the chip type determination reading unit is A mechanism for detecting the amount of movement M2 aligned with the specific pattern for the chip, storing the detected movement amounts M1 and M2, memorizing the specific pattern for the chip name within the reading area frame, and determining the type of the specific pattern for the chip name. A storage device storing materials, a mechanism for recalling these stored contents,
The present invention is characterized by comprising a pattern type recognition means for comparing the specific pattern for chip name and the type discrimination material of the specific pattern for chip name.

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 implementing the present invention. The automatic wafer prober 1 in this configuration example consists of a probing machine section 1a and a wafer transfer section 1b. In this probing machine section 1a, a wafer chuck table 5 (transporter) is moved within a horizontal plane (XY directions) and rotated within a horizontal plane in the θ direction. This makes it possible to arbitrarily change the relative position of the wafer with respect to the probe whose tips are arranged in correspondence with the measurement electrodes.

On the other hand, there is a chip inspection section using a probe at the position of the wafer chuck table 5 shown in FIG. ) are electrically connected with the required contact pressure. Further, as a reading section for chip type determination, a reading device such as an image pickup device ITV is provided which magnifies and photographs the wafer surface for automatic alignment including alignment and chip type determination. 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 probing machine section 1a. This transfer arm transfers the wafer transferred to the load stage 3 to the load position 5a.
The wafer is transferred onto the chuck table 5 which has been moved to On the other hand, the wafer whose measurement has been completed is transferred 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) 2 for installing cassettes containing wafers, with respect to the probing machine section 1a equipped with the above-mentioned automatic wafer loading/unloading mechanism.
belt conveyors 6a, 6b, 7 connected to each of the loading position 3 and unloading position 4 which also function as a pre-alignment stage.
It is composed of a 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 bus line BUS according to each control program as follows. The panel unit PANL is a microprocessor CPU
It starts and stops the program, inputs or instructs necessary preset information in each control program, inputs or instructs necessary preset information, and performs necessary display. It is also used to input control signals for manual control of the stage control unit STGC.

The loader section control unit RODC controls the elevator mechanism, belt conveyor, and prealignment, and also controls the transfer arm and wafer chuck table 5.

The stage control unit STGC drives a pulse motor in response to a pulse signal (one pulse corresponds to a predetermined amount of movement with high accuracy), and controls the X, Y, and Z stages and the θ stage. Control is performed according to each operating mode.

After the wafer is transferred 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 digitized by an A/D converter ADC and written to the storage device MEM. At this time, the wafer portion imaged by the image pickup device ITV is approximately 1 mm x 1 mm, although it is not particularly limited.

Next, this control system moves the wafer chuck table 5 in the X or Y direction via the stage control unit STGC to detect the scribe line, and further rotates the wafer chuck table 5 so that the direction of the scribe line is parallel to the X-axis direction. Adjust as follows. 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 below the probe without further rotation in the θ direction. In this way, the amount of movement of the wafer chuck table 5 is detected by a known movement amount detection means, and the amount of movement of the wafer chuck table 5 is detected by a known movement amount detection means.
Written to MEM. 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 are electrically connected to the inspection device TST via the probes, and various measurements and inspections are performed. The details of the above positioning operation can be found in, for example, Japanese Patent Application Laid-Open No. 1983
Although it is described in Japanese Patent No.-86739, etc., 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, manually move the first wafer to fit the specific pattern for the chip name within the reading area of the spatially fixed imaging device ITV from directly below the probe according to the following steps. The wafer chuck table 5 and the like are moved to a position where the wafer chuck table 5 can be moved, and the amount of movement of the wafer chuck table 5 (the amount of movement of the stage) is detected and stored.

(1) First, by manually operating the joystick, the chip ICM containing the specific pattern NK for the chip name located directly below the probe as shown in Fig. 4 is placed in the field of view of the imaging device ITV (display screen).
Wax chuck table 5 to fit inside
move. Specific pattern NK for chip name
is an appropriate size that the operator can see on the display screen, for example 30
It has a size of about 30 dots and a characteristic pattern. An example of this specific pattern NK for chip name will be described in detail later.

(2) Chips containing a specific pattern NK for chip names
When the ICM is placed within the field of view of the imager 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 to create a frame (reading area) that is the same as or slightly larger than the chip name specific pattern NK on the screen.
to be displayed at a specific position on the display screen.

(4) Next, move the frame so that the chip name specific pattern NK fits within it. Then, the amount of movement M2 is written into the storage device MEM.

(5) When the above operations are completed, the chip will move based on the movement amount M1 stored in step (2) above.
The ICM is moved directly below the probe again.

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, we will explain the procedure for reading the type of chip located directly below the probe.

(6) When a command to read the chip name is output from the upper computer of the measurement system in response to a command 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 directly below the imaging device ITV via the unit STGC.

(7) Next, after exposing the frame (reading area),
Transfer amount from the storage device MEM again in step (4) above
Read M2, move the frame by that amount, and capture the chip name specific pattern NK within that frame.

(8) Next, the pattern within this frame is
After being converted into an image signal by the A/D converter
It is written to the storage device MEM via the ADC as binary chip name information of brightness and darkness.

(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 performed by a pattern type recognition means that compares the type discrimination material of the chip name specific pattern stored in advance with the chip name specific pattern described above as the chip name information.

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

FIG. 5 is a diagram showing an example of a specific pattern for displaying chip types. Figure A shows a comb-shaped pattern, Figure B shows a dotted pattern, and the dotted lines indicate the imaging areas partitioned by the small frames. The shaded area is the area where a high brightness imaging signal is generated. This pattern is divided into two areas A and B by a dividing line 100. Area A is a portion constituting a chip type recognition signal, and area B is an alignment mark portion for the above-mentioned small frame. That is, the part B specifies the chip type reading area. In the dot array pattern shown in FIG. 2B, the portions B are provided at both ends, but they may be provided only at either end. In this example, area A is further divided into 5 areas.
It is divided so that combinations of light and dark can be created. In FIG. 5, each of these divided areas is labeled B1 to B5, respectively.

FIG. 6 is a diagram showing the structure of 26 types of chip name 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 V.

Furthermore, when the operator instructs the chip type to be determined, if the pattern cannot be placed within the frame using only the moving amount M2 of the frame in step (7) above, the B part of the pattern in Figure 5 will be placed in the frame. Adjust the position of the frame or wafer so that the chip name specific pattern is included within the reading area. To do this, it is sufficient to move the frame in the direction in which all the imaging signals in the b part 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.

The above has described an automatic chip type confirmation device that displays a frame that is the same as or slightly larger than the specific pattern NK for chip names on the screen. This is a recognition area to be set as a recognition area, and the shape of the area may be arbitrary. In addition, the reading part of the brightness necessary for recognizing the chip type described in step (9) above can be obtained by reading the necessary brightness information for each area within the defined area of each divided area B1 to B5 in part A of Fig. 5. Enough. Therefore, the recognition area for obtaining the information necessary for chip type recognition can be created by, for example, making the width of the above frame extremely small (in the minimum case, one scanning line for reading) and dividing it into each of the above definition areas. It can also be set to penetrate.

The specific pattern for the chip name can also be easily defined using characters such as alphabets or symbols indicating the product name. Furthermore, it is also possible to easily define and use part of the circuit and element patterns specific to the chip. 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 specific pattern for the chip name is stored in advance as chip type identification material,
The chip type can be recognized 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. Also,
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 name specific pattern set for the chip located at that location is known in advance, that value shall be used. It is sufficient to store it in the memory using the movement amount setting means.

As explained above, in the present invention, only for the first wafer, a specific pattern for the chip name of the chip located directly under the probe tip is transferred to the imaging device ITV by manual operation.
If you memorize the amount of movement to the pattern recognition area within the field of view, you can check the chip name directly under the probe at any time thereafter.
For example, research, development stage wafers or different
Even if the wafer is composed of chips with different types of elements and circuits, such as a completed wafer containing an IC, 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, these programs can be scheduled in an orderly manner based on the chip type confirmation, and various measurements can be performed automatically. There are advantages to implementing it.

Furthermore, if a chip type is set unique to each chip, the chip itself can be used as having a designation function. Even if the wafer is later divided into chips, this makes it possible to determine the position of the chip, and is also effective in determining the correspondence with the characteristic evaluation values.

In addition, it is necessary for the probe to be in proper contact with the pad for measurement, but for example, if the probe malfunctions due to external noise and shifts by one chip, or if the needle comes off the pad. You can also deal with the situation. This means that when automatically probing a number of wafers without human intervention, it is possible to stop the test without collecting invalid data, and to prevent electrical damage to the device. There are special effects such as

[Brief explanation of drawings]

FIG. 1 is a chip pattern diagram showing an example of a research wafer, FIG. 2 is a plan view showing an example of the configuration of an automatic wafer prober that implements the present invention, and FIG. 3 is an implementation of the control system of the automatic wafer prober shown in the second diagram. A block diagram showing an example, FIG. 4 is a chip pattern diagram for explaining the prober operation, FIG. 5 is a line diagram showing an example of a specific pattern for chip name, and FIG. 6 is a diagram of a specific pattern for chip name shown in FIG. 5. FIG. 3 is a diagram illustrating classification based on differences in pattern shapes. 1 is an automatic wafer prober, 1a is a probing 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 the unload position, 5
c is the photographing position, 6a, 6b, 7a, and 7b are the belt conveyors, ITV is the imaging device, CPU is the microprocessor, PANL is the panel unit,
STGC is the stage control unit, RODC is the loader control unit, MEM is the storage device, and ADC is the A/
D converter, I/O is input/output interface,
TST is inspection equipment, PC is probe card, 100
is a dividing line for explaining the role of the pattern, A is a pattern type definition area, and B is an area for positioning a small frame for pattern type recognition.

Claims (1)

[Scope of Claims] 1. A chip inspection section using a probe and a reading section for determining the chip type are placed side by side in a probing machine section, and the chip inspection section using a probe has a wafer chuck table that detects the electrodes of the probe and the chip. The amount of movement M1 from the fixed fixed position on the wafer to the chip type determination reading unit is detected, and the reading area frame exposed by the chip type determination reading unit is used as a specific pattern for chip name. a movement amount detection mechanism that detects a movement amount M2 aligned with the chip name; a movement amount detection mechanism that stores the detected movement amounts M1 and M2; stores a specific pattern for the chip name within the reading area; a storage device storing pattern type discrimination data; a movement amount setting mechanism for reading the movement amounts M1 and M2 from the storage device; and type discrimination data for the chip name specific pattern and the chip name specific pattern. 1. An inspection apparatus having an automatic type confirmation mechanism for chips in a wafer, comprising a pattern type recognition means for comparing patterns.