JPH0548621B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a device for determining non-defective pellets.

[Prior Art] A semiconductor wafer is formed by printing circuit patterns on the surface layer of a circular wafer made of a material such as silicon and having a mirror surface with high reflectivity.
The circuit pattern group consists of multiple circuit patterns
It is arranged and configured in the direction. The shape of the group of circuit patterns to be printed is a square or rectangle that fits within the circular wafer, and the surface of the semiconductor wafer other than the part where the circuit patterns are printed is left as a mirror surface with high reflectance. Ru. The semiconductor wafer on which the circuit patterns have been printed is diced into matrix shapes, and further broken into pellets. Dicing is
This is done by cutting dicing lines in the X and Y directions on the surface of the semiconductor wafer using a diamond grindstone, laser, or the like. Thereby, by breaking the semiconductor wafer along the dicing line and separating it, pellets having a circuit pattern on the surface can be manufactured. The pellets produced in this manner are mounted on a substrate such as a lead frame using a pellet bonding device, thereby producing chips such as ICs and LSIs.

Incidentally, a group of circuit patterns to be printed on a circular wafer is broken into pellets in advance, and a circuit characteristic test is conducted for each circuit pattern before being separated. The circuit characteristic test is carried out using a characteristic testing machine, and the probe of the testing machine is brought into contact with the surface electrode of the printed circuit pattern, thereby making it possible to inspect whether each circuit pattern is good or bad. As a result of the circuit characteristic test, a defective mark is displayed in red or other ink by a mark display device on the surface of the circuit pattern corresponding to a defective pellet determined to be defective. Furthermore, a mark display device is used to display a defective mark in red or other ink at a position corresponding to the surface of the defective pellet on which the circuit pattern is not printed.

The semiconductor wafer undergoes the defect marking operation as described above, and is then broken into pellets and separated. As a result, a circuit pattern is formed on the surface, and the surface becomes a reflective surface with low reflectance.As a result of the above circuit characteristic test, a defective pellet with a defect mark displayed on the surface and a circuit pattern are formed on the surface. A defective pellet with a defective mark displayed on the surface, and a circuit pattern formed on the surface and the surface being a reflective surface with a low reflectance. As a result of the above circuit characteristic test, good pellets with no defect marks displayed on their surfaces were formed. In order to distinguish good pellets from these defective and non-defective pellets and perform pellet bonding work only on the good pellets,
A device was used to identify good pellets.

The device for identifying non-defective pellets includes an inspection light source that can irradiate inspection light onto the surface of the pellet, a reference reflected light amount equivalent value that allows determining the presence or absence of a defective mark on each pellet, and a A defective mark detection means is provided for measuring the amount of light and comparing the measured value equivalent to the amount of reflected light and the value equivalent to the reference amount of reflected light. That is, the defective mark detection means of this device detects whether a defective mark is displayed on the surface of the pellet based on the fact that the value equivalent to the reflected light amount on the pellet surface of the inspection light irradiated to the defective mark is lower than the level of the reference reflected light amount equivalent value. This makes it possible to determine the presence or absence of defective marks. As a result, it becomes possible to recognize and discriminate pellets for which no defect mark has been detected as good pellets, and pellet bonding work is performed only on pellets that are judged to be good pellets.

[Problems to be Solved by the Invention] However, in the conventional non-defective pellet discriminating device described above, although pellets with different surface reflectances coexist, the standard for discriminating defective marks is usually not met. The only value corresponding to the amount of reflected light was set that matched the reflectance of the pellet with a circuit pattern formed on its surface. Therefore, if the reflectance of the pellet surface is high, such as a defective pellet with no circuit pattern formed on its surface, the amount of reflected light measured by the defect mark detection means will be correspondingly large as a whole, and therefore the In defective pellets, it has been difficult to distinguish defective marks due to a decrease in the amount of reflected light.

The present invention makes it possible to reliably detect defective marks on the pellet surface even when the reflectance of the pellet surface differs depending on whether or not a circuit pattern is formed. The purpose is to promote

[Means for Solving the Problems] The present invention has a circuit pattern formed on a surface, the surface is a reflective surface with low reflectance, and as a result of a circuit characteristic test, a defect mark is displayed on the surface. For each pellet, a defective pellet with no circuit pattern formed on its surface, the surface of which is a reflective surface with high reflectance, and a defective mark displayed on the surface, a good pellet with no defective mark displayed. This is a device for identifying non-defective pellets, which includes an inspection light source that can irradiate inspection light onto the surfaces of each of the non-defective pellets and non-defective pellets arranged on a table, and the presence or absence of a defective mark on each pellet. a defective mark detection means for predetermining a value equivalent to the reference amount of reflected light that is possible, measuring the amount of reflected light of the inspection light, and comparing the measured value equivalent to the amount of reflected light and the value equivalent to the reference amount of reflected light; and an inspection light amount of the inspection light source. The standard light amount value is such that the reflected light amount equivalent value of the inspection light for the defect mark of a defective pellet with a circuit pattern formed on its surface is lower than the reference reflected light amount equivalent value, and and means for changing the setting to a corrected light amount value such that the value corresponding to the amount of reflected light of the inspection light for the defect mark of the defective pellet is at a lower level than the value equivalent to the reference amount of reflected light.

[Function] Under the condition where the inspection light amount is set to the reference light amount value, the reflected light amount equivalent value of the inspection light when the defective mark detection means detects a defective mark on a defective pellet having a circuit pattern is less than the reference reflected light amount equivalent value. To detect a low level and to reliably detect a defective mark existing on the surface.

Under the condition where the inspection light amount is set to the corrected light amount value, the reflected light amount equivalent value of the inspection light when the defective mark detection means detects a defective mark on a defective pellet that does not have a circuit pattern is at a level lower than the reference reflected light amount equivalent value. By detecting this, it is possible to reliably detect a defective mark existing on the surface even though the amount of reflected light on the surface is large overall due to the absence of a circuit pattern.

As a result of the above, even if the reflectance of the pellet surface differs depending on the presence or absence of circuit pattern formation, it is possible to reliably detect defective marks on the surface, thereby ensuring reliable identification of good pellets. It is possible to aim for

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway front view showing a non-defective pellet discriminating device according to an embodiment of the present invention, FIG. 2 is a plan view showing a semiconductor wafer before it is broken into pellets and separated, and FIG. The figure is a plan view showing good and defective pellets arranged on an XY table, Figure 4 is a plan view showing an enlarged part of Figure 3, and Figure 5 shows the variable setting state of the inspection light intensity of the inspection light source. FIG.

The semiconductor wafer 10 shown in FIG. 2 has a circuit pattern group 11 on the surface layer of a circular wafer made of silicon or the like and having a mirror surface with high reflectance.
can be burned. The outline of this circuit pattern group 11 is a rectangular shape that fits within a circular wafer, and is composed of a plurality of circuit patterns 12 arranged in the XY directions. As a result, the surface of the semiconductor wafer 10 other than the portion where the circuit pattern 12 is printed remains as a mirror surface with high reflectance. Semiconductor wafer 1 on which circuit pattern group 11 is printed
0 is diced along matrix-like dicing lines 13 and further braked.
As a result, by breaking and separating the semiconductor wafer 10 along the dicing line 13, it is possible to obtain a plurality of pellets having the circuit pattern 12 on the surface.

The semiconductor wafer 10 has a printed circuit pattern 1 before being broken into pellets and separated.
Circuit characteristic tests were conducted for each of 2.
The test is conducted using a characteristic testing machine (not shown). That is, the circuit characteristic test is performed by bringing the probe of the characteristic testing machine into contact with the surface electrode of the printed circuit pattern 12, thereby making it possible to inspect whether each circuit pattern 12 is good or bad. As a result of the circuit characteristic test, a defective mark 14 is displayed in red or other ink on the surface of the circuit pattern 12 determined to be defective by a mark display device (not shown). Furthermore, the mark display device displays the circuit pattern 1 on the surface of the semiconductor wafer 10.
Part 15 corresponding to defective pellets that are not baked in No. 2
The defective mark 14 is also displayed in ink such as red.

Semiconductor wafer 1 subjected to the above circuit characteristic test
0, after the above-mentioned defect mark display operation, a good pellet discriminating device 41 as shown in FIG.
The pellets are separated into pellets, and then a process is performed to determine which pellets are good.

The non-defective pellet discriminating device 41 includes an XY table 18 that is movable in the XY directions with respect to a pedestal 17, and a support ring 19 that supports the semiconductor wafer 10 can be attached to the XY table 18. . The support ring 19 is attached to the support part 21 of the support frame 20, and the support frame 20 is
It is fixed to the upper surface of the XY table 18 by bolts 22. The semiconductor wafer 10 supported by the support ring 19 is adhered to the upper surface of the adhesive sheet 23.
That is, the semiconductor wafer 10 subjected to the circuit characteristic test is adhered to the adhesive sheet 23 and then broken along the dicing line 13 and separated.
By heating the adhesive sheet 23 in this state and further stretching the sheet 23 in the circumferential direction of the semiconductor wafer 10, pellets are arranged at regular intervals in the XY direction on the upper surface of the adhesive sheet 23. The peripheral edge of the adhesive sheet 23 is stuck to a groove 24 formed on the side of the support ring 19 via a rubber ring 25. As a result, as shown in FIG. 3, a circuit pattern 12 is formed on the surface of the XY table 18, and the surface becomes a reflective surface with low reflectance. Defective pellet 26 with mark 14 displayed
A defective pellet 27 has no circuit pattern 12 formed on its surface, the surface is a reflective surface with high reflectance, and a defective mark 14 is displayed on the surface.
A circuit pattern 12 is formed on the surface, and the surface is a reflective surface with low reflectance, and as a result of the circuit characteristic test, each of the good pellets 28 on which no defect mark 14 is displayed on the surface is They will be aligned in the direction.

An inspection light source 2 is located above the XY table 18.
9 and a sensing section 31 of a sensor 30 serving as defective mark detection means are provided. The inspection light source 29 is capable of irradiating inspection light 32 onto each of the non-defective pellets 28 and the defective pellets 26 and 27 arranged on the adhesive sheet 23. Also, sensor 3
The sensing section 31 of No. 0 detects the inspection light 3 reflected from the good pellet 28 or the defective pellet 26 or 27.
It is possible to detect changes in the amount of reflected light. The sensing area Q of the amount of reflected light by the sensing unit 31 is the width W1 of each pellet 26, 27, 28, as shown in FIG.
The amount of reflected light on each pellet 26, 27, 28 is detected by moving the XY table 18 in the X direction or the Y direction. XY
This is done by moving each pellet 26, 27, 28 to be aligned in the direction. As a result, as shown in FIG. 5, the sensing area Q of the sensing section 31 scans the aligned pellets 26, 27, 28 in the direction of arrow A, and The magnitude of the amount of reflected light is sensed by the sensing section 31.

The sensor 30 detects defect mark 1 on the pellet surface.
A good pellet 28 discrimination circuit 4 that can detect the presence or absence of a good pellet 28 and memorize the coordinate position of the good pellet 28.
2 is provided. Discrimination circuit 4 for good pellets 28
2 includes a voltage conversion section 43, a comparison section 44, an inspection light amount setting section 45, a reference reflected light amount equivalent section setting section 46,
It is composed of a good pellet discrimination section 47 and a storage section 48. The voltage conversion unit 43 converts the change in the amount of reflected light detected by the sensing unit 31 into a change in the output voltage V1, and the output voltage V1 is output to the comparison unit 44 and the inspection light amount setting unit 45, respectively. As a result,
Changes in the amount of reflected light on the surfaces of the pellets 26, 27, and 28 based on the movement of the XY table 18 shown in FIG. 5 are transmitted to the comparison section 44 and the inspection light amount setting section 45 as a voltage V1. At this time, the voltage V1 is high when the amount of reflected light from each pellet 26, 27, 28 is large, and becomes low when the amount of reflected light is small. Therefore, the voltage V1 is applied to the region B where the defective mark 14 on the defective pellet 26 is detected and the defective mark 14 on the defective pellet 27.
In the region C where this is sensed, the voltage V1 is lower than the voltage V1 based on the normal amount of reflected light on the surfaces of the respective defective pellets 26 and 27. In addition, the voltage V1 is applied to the circuit pattern 12 on the surface.
Compared to the defective pellet 26 on which the circuit pattern 12 is formed and the good pellet 28, the defective pellet 27 on which the circuit pattern 12 is not formed exhibits a higher overall value due to the higher reflectance of the surface.

The comparison unit 44 determines a reference voltage level L based on the transmitted voltage V1 and a preset reference amount of reflected light.
3, it is possible to detect a change in the voltage V1 that decreases when the defective mark 14 is detected.
The setting of the reference voltage level L3 is performed by the setting section 46, and the comparison section 44 is set with a constant reference voltage level L3.
It is possible to output.

On the other hand, the inspection light amount setting section 45 controls the inspection light source 29
The amount of inspection light emitted by the sensor can be variably set. That is, in this embodiment, the test light amount setting unit 45 sets the test light amount emitted by the test light source 29 to a reference light amount value D1 and a corrected light amount value D2 indicating a light amount value lower than this reference light amount value D1. It is now possible to change settings.

Here, the reference light amount value D1 means that when the inspection light amount is set to this reference light amount value D1, the sensing unit 31 detects the defect mark 14 of the defective pellet 26 on which the circuit pattern is formed, as shown in FIG. When sensed, the voltage V1 outputted from the voltage converter 43 to the comparator 44 in the sensing region B is set to a value that is locally lower than the reference voltage level L3.

Further, the corrected light amount value D2 is the reference light amount value D for the defective pellet 27 on which no circuit pattern is formed.
Output voltage V1 when an inspection light amount of 1 is irradiated
It is possible to reduce the change E to the change F by irradiating the inspection light set to this corrected light amount value D2, and under the condition where the inspection light amount is set to this corrected light amount value D2, the defect When the sensing section 31 senses the defective mark 14 on the pellet 27, the voltage V1 outputted from the voltage converting section 43 to the comparing section 44 in the sensing area C is set to be locally lower than the reference voltage level L3. be done. At this time, since the output voltage V1 based on the amount of light reflected from the good pellets 28 is below the reference voltage level L3 as a whole, the defective pellets 27 and the good pellets 28 can be distinguished.

Therefore, the setting section 45 sets the normal inspection light amount to the reference light amount value D1, and the comparison section 44 detects a decrease in the output voltage V1 when the sensing section 31 senses the defective mark 14 on the defective pellet 26. In some cases, a defective pellet 26 is detected.

Then, when the comparing section 44 does not detect a defective pellet 26 under the above-mentioned normal setting state, the setting section 45 performs an inspection on the assumption that the pellet is either a defective pellet 27 or a non-defective pellet 28. The light amount is set to the corrected light amount value D2.
In this way, under the condition that the setting section 45 sets the inspection light amount to the corrected light amount value D2, the comparison section 44 calculates the decrease in the output voltage V1 when the sensing section 31 senses the defective mark 14 on the defective pellet 27.
When it is detected, it is detected that there is an insufficient amount of pellets 27.

As a result, in the comparator 44, the local voltage changes in each area of B and C are at the reference voltage level L3.
As shown in FIG. 5, a determination pulse P of 0 indicating that the defective mark 14 has been determined can be output to the non-defective pellet determination section 47. On the other hand, in other cases, that is, when no local voltage drop is measured in comparison with the reference voltage level L3, the pellet is considered to be the good pellet 2.
A discrimination pulse P of 1 indicating that the pellet is 8 can be output to the good pellet discrimination section 47.

The good pellet discriminating section 47 uses the defective mark discriminating pulses P sequentially inputted from the comparing section 44 to
The position of each pellet 26, 27, 28 with respect to an arbitrary coordinate origin on the non-defective pellet discriminating device 41 is analyzed. As a result, good pellets 2 out of the arranged pellets 26, 27, 28
The coordinate position of the pellet 8 is analyzed, and the coordinate position of the good pellet 28 is stored in the storage section 48. Storage in the storage unit 48 is performed using a storage medium such as a floppy disk or magnetic tape. In this way, each pellet 26, 2 whose coordinate position of the good pellet 28 has been determined
7 and 28, sorting work is performed by a good pellet sorting section of the pellet bonding device, and the sorting work is performed based on data regarding the coordinate position of the good pellets 28 stored in the storage medium. ing.

Good pellet discrimination device 41 according to the above embodiment
According to the above, when a defective mark 14 is detected by comparing the output voltage V1 based on the amount of reflected light from the pellet with the reference voltage level L3 under the condition that the inspection light amount is set to the reference light amount value D1, the pellet It can be seen that this is a defective pellet 26. On the other hand, if the defective mark 14 is not detected under this condition, the pellet is either a defective pellet 27 or a non-defective pellet 28. Therefore, if the defective mark 14 is detected when the inspection light intensity is set to the corrected light intensity value D2 in the inspection light intensity setting section 45, that pellet is detected as a defective pellet 27, and finally the non-defective pellet 28 is reliably detected. It is possible to distinguish between them.

According to the device 41 for determining good pellets according to the above embodiment, it is possible to discriminate between good pellets 28 by variable setting of the light intensity values D1 and D2 of the inspection light intensity, but the reference voltage level L3 can also be variably set. As such, the sensor 30 may be provided with a circuit 42 for determining good pellets.

Further, in the above embodiment, the sensor 30 is a line sensor, and the sensing area Q is linear, but in the defective mark detection means of the present invention, the sensing area is a surface that can sense the entire surface of each pellet. It can also be used as a sensor.

[Effects of the Invention] As described above, according to the present invention, even when the reflectance of the pellet surface differs depending on whether a circuit pattern is formed or not, it is possible to reliably detect defective marks existing on the surface. This makes it possible to ensure the identification of good pellets.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing a non-defective pellet discriminating device according to an embodiment of the present invention, FIG. 2 is a plan view showing a semiconductor wafer before it is broken into pellets and separated, and FIG. The figure is a plan view showing good and defective pellets arranged on an XY table, Figure 4 is a plan view showing an enlarged part of Figure 3, and Figure 5 shows the variable setting state of the inspection light intensity of the inspection light source. FIG. 12... Circuit pattern, 14... Defective mark,
18...XY table, 26, 27...defective pellet, 28...good pellet, 29...inspection light source, 30...sensor, 32...inspection light, 41...
Good pellet discrimination device, 42... Good pellet discrimination circuit, 45... Inspection light amount setting unit, 46...
... Reference reflected light amount equivalent value setting section, 47 ... Good pellet discrimination section, L3 ... Reference voltage level, D1 ...
...Reference light amount value, D2...Corrected light amount value.

Claims (1)

[Claims] 1 A defective pellet has a circuit pattern formed on its surface, the surface is a reverse slope with low reflectance, and a defective mark is displayed on the surface as a result of a circuit characteristic test, and a defective pellet has no circuit pattern formed on its surface. A device for identifying good pellets, the surface of which has an inverted slope with high reflectance, and which is capable of distinguishing good pellets with no defect mark displayed from each defective pellet with a defect mark displayed on the surface. , predetermining an inspection light source that can irradiate inspection light onto the surfaces of each of the good and defective pellets arranged on the table, and a reference reflected light amount equivalent value that makes it possible to determine the presence or absence of a defective mark on each pellet; defective mark detection means for measuring the reflected light amount of the inspection light and comparing the measured reflected light amount equivalent value with the reference reflected light amount equivalent value; A reference light amount value at which the value equivalent to the reflected light amount of the inspection light for the defective mark on the pellet is lower than the reference reflected light amount equivalent value, and a value equivalent to the reflected light amount of the inspection light for the defective mark of the defective pellet on which no circuit pattern is formed on the surface. and means for changing the setting to a corrected light amount value whose value is lower than the reference reflected light amount equivalent value.