JPH0550363A - Blade position detector and judging method of reliability thereof - Google Patents

Abstract

PURPOSE:To position the tip of a rotary blade so accurately in a noncontact state in response to a variation of wear in the blade. CONSTITUTION:A pair of prisms 36, 38 are opposedly installed at a specified interval, and a light projected out of a light emitting diode 16 is condensed within the specified interval by the prism 36 on one side, while the light diffused after once condensed by the prism 38 on the other is recondensed. A photodiode 23 receives the light so far condensed by the prism 38 on the other. In addition, a disturbance light and a noise are eliminated by an amplifier 22, and only the light projected out of the light emitting diode 16 is taken out. In succession, a blade 54 shades the light condensed at the center of the specified interval, and reading means 45A, 45B reads a light received variable of the photodiode 23 while it reads displacement of the blade 54. Then, a comparator 74 outputs a signal when the light received variable of the photodiode 23 has accorded with the prestored setting valve, positioning a tip of the blade 54 conformed to wear or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blade position detecting device and a method for determining its reliability, and more particularly to a blade for detecting wear of a high-speed rotating blade of a dicing device for grooving a wafer in semiconductor manufacturing or the like. The present invention relates to a position detection device and a reliability determination method thereof.

[0002]

2. Description of the Related Art It is an important factor to match the uncut amount of a work with a set value in a dicing machine, and in order to match the uncut amount of the work with the set value, positioning of the Z axis and repetition of positioning are high. It is necessary to carry out with accuracy and to detect and correct the amount of wear of the blade.

The following two methods are known as methods for correcting the amount of blade wear. The first method is a method of correcting the blade by processing the preset number of processing lines of the work and then bringing the blade into contact with the processing table to energize the blade and the processing table. Second
In this method, the data (experience value) of the blade wear amount is input in advance as an automatic wear correction amount to the dicing device.

[0004]

However, the first method has a problem that the blade is brought into contact with the working table, so that the blade is damaged, and further, the working table is scratched. Further, the second method has a problem that the amount of wear of the blade changes depending on conditions such as the type of work to be machined, the variation of the blade, and the cut amount, so that the experience value cannot cope with these changes.

The present invention has been made in view of the above circumstances, and the amount of wear of the blade depends on conditions such as the type of work to be processed, the variation of the blade, and the cut amount without contacting the blade with the processing table. It is an object of the present invention to propose a blade position detecting device and a method for determining its reliability that can cope with these changes when they change.

[0006]

In order to achieve the above-mentioned object, the present invention is provided so as to face the light projecting means at a predetermined interval, and one of the light projected from the light projecting means A pair of optical systems in which the optical system collects the light within the predetermined interval and the light diffused after the collection is collected in the other optical system, and the light collected in the other optical system is received and photoelectrically converted. Light receiving means, means for removing ambient light received by the light receiving means and generated noise, and light that is moved within a predetermined interval of the optical system orthogonal to the optical axis and condensed within the predetermined interval. A light-shielding rotary blade, a means for reading the light-receiving amount of the light-receiving means and a displacement of the rotary blade, and a means for outputting a signal when the light-receiving amount of the light-receiving means matches a preset value. Based on the displacement position of the rotary blade when the signal is output, In the blade position detecting device for positioning the tip of the rotary blade, after cutting a predetermined number of works with the rotary blade, the pair of optical systems are washed, and the rotary blade is positioned at a non-light-shielding position of the condensed light. When the light receiving means receives light that has passed through the pair of optical systems, and the received light quantity V0 substantially matches the previously stored light quantity V1 when the pair of optical systems is kept clean, the optical Each time the rotary blade is moved by a predetermined amount in the direction of blocking the light condensed within the system interval, the light amount V received by the light receiving means and the displacement Z of the rotary blade are stored, and the stored light receiving means is stored. The relationship between the amount of light V received at and the displacement Z of the rotary blade is obtained,
When the obtained relationship is substantially equal to the positional relationship between the light receiving amount and the rotary blade of the pair of optical systems in a clean state, it is determined that the pair of optical systems are clean.

[0007]

According to the present invention, a pair of optical systems are provided so as to face each other at a predetermined interval, and the light projected from the light projecting means by one optical system of the pair of optical systems is condensed within the predetermined interval. At the same time, the light diffused after being condensed by the other optical system is condensed again. The light receiving means receives the light condensed by the other optical system and photoelectrically converts it. Further, means for removing the ambient light received by the light receiving means and the generated noise is provided, whereby only the light projected by the light projecting means is output from the light receiving means.

Further, the rotary blade moves at the center of a predetermined interval to shield the condensed light, and the reading means reads the amount of light received by the light receiving means and also reads the displacement of the rotary blade. Then, the means for outputting a signal outputs a signal when the amount of light received by the light receiving means matches a prestored set value, and positions the tip of the rotary blade.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a blade position detecting device and its reliability determining method according to the present invention will be described below in detail with reference to the accompanying drawings. As shown in FIG. 1, the clock 12 of the blade position detecting device 10 drives the transistor 14,
At the same time that the light emitting diode 16 is in the "ON" state, the first switch 18 is in the "OFF" state and the second switch 20 is in the "ON" state. Further, the clock 12 drives the transistor 14 to turn the light emitting diode 16 into the “OFF” state, and at the same time, turns the first switch 18 into the “ON” state and the second switch 20 into the “OFF” state. As a result, switching is performed between the case where the operational amplifier 22 described later is connected to the amplifier 24 and the case where the operational amplifier 22 is connected to the amplifier 26.

One end of the optical fiber 28 is the light emitting diode 1
6 is provided in the vicinity, and the other end is provided on the inspection table 30. The inspection table 30 is provided on the base 31,
A lens system 34 is provided on the inspection table 30 so as to be located above the other end of the optical fiber 28. Further, prisms 36 and 38 are provided on the inspection table 30.

The prism 36 is located above the lens system 34, and the lens system 40 is provided below the prism 38. The optical fiber 32 is provided below the lens system 40.
One end of the operational amplifier 22 is provided at the other end.
Is provided in the vicinity of the photodiode 23. Therefore, the light projected from the light emitting diode 16 enters the lens system 34 through the optical fiber 28, and the light refracted by the lens system 34 is reflected by the prism 36 and the prism 36,
It is condensed in the prism 38. The condensed light is reflected by the prism 38, refracted by the lens system 40, and enters one end of the optical fiber 32. The light entering one end of the optical fiber 32 illuminates the photodiode 23 of the operational amplifier 22. At this time, the ambient light is simultaneously emitted from the photodiode 23.
To reach.

A signal photoelectrically converted by the photodiode 23 is input to the negative terminal of the operational amplifier 22. This signal includes an electric signal of light emitted from the light emitting diode 16 and an electric signal of disturbance light. In addition, the light emitting diode 16 is connected to the “+” pole of the operational amplifier 22 from the integrating circuit composed of the amplifier 24 and the capacitor 44.
The offset voltage in the state of "F" is output. When the clock 12 puts the light emitting diode 16 into the “OFF” state (see FIGS. 2A and 2B), the first switch 18 goes into the “ON” state and the second switch 20 goes into the “OFF” state at the same time. Therefore, the offset voltage includes an electric signal of ambient light, electric noise generated in the operational amplifier 22, and the like (see FIG. 2B). Therefore, the output of the operational amplifier 22 becomes 0 when the light emitting diode 16 is in the “OFF” state (see FIG. 2C).

The capacitor 44 also stores an offset voltage. Therefore, when the light emitting diode 16 is turned on, the first switch 18 is also turned off at the same time. However, since the offset voltage is stored in the capacitor 44, the operational amplifier 22 uses the disturbance light or the electric power. The electrical signal of only the light of the light emitting diode 16 is output by removing the static noise.

Further, when the light emitting diode 16 is turned on, the second switch 20 is turned on at the same time, and the capacitor 46 stores the voltage output from the operational amplifier 22. The capacitor 46 holds the accumulated voltage when the light emitting diode 16 is in the “OFF” state, that is, when the second switch 20 is in the “OFF” state. As a result, the signal output from the amplifier 26 becomes a curve shown in FIG.

The signal output from the amplifier 26 is read via the AD converter 70 of the light quantity reading means 45A and is input to the comparator 74. The comparator 74 compares the signal output from the amplifier 26 with the threshold value signal described below output from the storage means 47 and outputs a signal to the one-shot 76 when the respective signals match. The one-shot 76 outputs a C-SET signal based on the signal from the comparator 74. The storage unit 47 stores a threshold value in advance,
The threshold value is output to the comparator 74 via the DA converter 72.

A blade 5 is provided above the prisms 36 and 38.
4, the blade 54 is rotatably provided on the moving device 62. The moving device 62 is in the Y-axis direction, Z
Since the blade 54 moves in the axial direction, the blade 54 also moves in the Y-axis direction and the Z-axis direction. The moving device 62 is provided with blade displacement reading means 45B, and the blade displacement reading means 45B reads the displacement of the blade 54 in the Z-axis direction. still,
The movement in the X-axis direction is performed by the base 31.

FIG. 3 shows a state in which the work 52 is processed by the dicing device 50, and FIG. 4 shows a state in which the blade 54 of the dicing device 50 is set in the blade position detecting device. Inspection table 3 as shown in FIGS.
A pipe 56 for supplying water and air is provided near 0, and a nozzle 56A is attached to the tip of the pipe 56. As a result, the surfaces of the prisms 36 and 38 facing each other can be washed with water, and the water can be dried with air after washing, so that the surfaces of the prisms 36 and 38 facing each other can be kept clean.

In FIG. 1, FIG. 3, and FIG. 4, 60 is a work table. The operation of the blade position detecting device according to the present invention configured as described above will be described in detail with reference to the flowchart shown in FIG. First, the prism 36 and the prism 3
The opposing surfaces of 8 are washed with water, and after washing, the water is dried with air to keep the opposing surfaces of the prisms 36 and 38 clean (step 80). Next, the blade 54 is moved in the Y direction and the base 31 is moved in the X axis direction to set the blade 54 at the inspection position of the prisms 36, 38 facing each other (step 82). Next, based on the clock 12, the light emitting diode 16 is alternately converted into the "ON" and "OFF" states, and the light amount data output from the amplifier 26 is read via the light amount reading means 45A. Then, it loops until the read light amount data continues for a certain time (step 84).

In this case, the operational amplifier 22 removes ambient light, electrical noise, etc., and outputs an electrical signal of only the light of the light emitting diode 16. After the loop is completed, it is checked whether the read light amount data is equal to or more than a predetermined value (that is, the light amount data V1 when the prisms 36 and 38 keep the blade 54 clean so that the blade 54 can be inspected) (step). 86). Next, the read light quantity data is recorded in the memory as the initial light quantity V0 (step 8).
8).

Next, the value (V0 / 2) is set in the storage means 47 as a threshold value (step 9).
0). After the setting is completed, the blade 54 is lowered by one pulse (Z
(Moving downward in the direction), the displacement amount of the blade 54 is read by the blade displacement reading means 45B (step 9).
2) Read the light intensity data at that position (step 9)
4). After recording the read light amount data in the memory (step 96), 1 is added to the memory address (step 100).

Then, steps 92 to 106 are sequentially repeated until the blade 54 shields the entire area of the sampling area 102 (that is, the area of the light beam reflected by the prism 36) shown in FIG. During this repetition, the blade 54 descends and the light amount data starts to decrease from the position where the blade 54 reaches the sampling area 102. Next, when the light amount data matches the threshold value, the C-SET signal is output from the one shot 76 via the comparator 74 shown in FIG. The position of the blade 54 when the C-SET signal is output is set to Zc, and this position is set as the reference position of the blade 54 to set the reference position Zc.
And the surface position Zt of the work table 60 determined in advance
Relative difference Zd (that is, Zd = | Zc−Zt |) is stored.

The surface position Z of the work table 60 described above.
To obtain t, use the blade 54 and the work table 60.
The blade 54 and the work table 60 are energized by making contact with the surface of the blade 54 and the position of the blade 54 at this time is detected to be the surface position Zt. Then, once the relative difference Zd is stored,
Even if the blade 54 is replaced and the outer diameter of the blade is different, if the reference position Zc is detected, the new blade surface position Zt (that is, Zt = | Zc−Zd |) is stored based on the stored relative difference Zd. ) Can be calculated.
As a result, the uncut amount of the work 52 can be set to the set value.

Further, when the blade 54 is lowered, the entire sampling area 102 is shielded and the light quantity data becomes zero. When the blade 54 is descended in this way, the outer diameter of the blade 54 is sufficiently larger than the diameter of the sampling area 102, and the opposing surfaces of the prism 36 and the prism 38 are kept clean. Is located approximately in the middle of the position (Za) where the light amount data starts to decrease and the position (Zb) where the light amount data becomes 0 (see FIG. 6). That is, the relationship of (Za + Zb) / 2≈Zc is established.

Then, the relationship between the value obtained by integrating this (VZ) curve and dividing each integrated value (ΔV / ΔZ) by (maximum integrated value) and the position Z of the blade 54 is input in advance. (ΔV / Δ when the prisms 36 and 38 being cleaned are in a clean state
ZZ) The shape of the curve is substantially the same. As a result, it is determined that the prisms 36 and 38 are in a clean state (that is, a range in which sufficient measurement accuracy can be obtained). Therefore, the position Zc of the blade 54 when the C-SET signal is output is set as the reference position of the blade 54, and the surface position Zt of the work table 60 is calculated from the previously determined relative difference Zd. Then, the blade 54 is moved onto the work 52 to lower the blade 54 to a position where the set uncut amount of the work 52 is secured, and the work 52 is cut.

On the other hand, when the opposite surfaces of the prism 36 and the prism 38 are unevenly attached, Zc is not located in the middle between Za and Zb as shown in FIG.
The (ΔV / ΔZ-Z) curve is also input in advance (ΔV /
ΔZ-Z) deviates from the shape of the curve. Therefore, in this case Z
The coordinate position of c is error-processed as an unreliable value (steps 108 and 110).

Further, when the opposite surfaces of the prisms 36 and 38 are substantially uniformly soiled, Zc is located in the middle between Za and Zb as shown in FIG. 8, and (ΔV / Δ
(Z-Z) curve is also input in advance (ΔV / ΔZ-Z)
It roughly matches the shape of the curve. Therefore, if the dirt is substantially uniform, even if the read initial light amount V0 is lower than a predetermined value (that is, the light amount data when the prisms 36 and 38 keep the blade 54 inspectable and clean). Up to a certain degree (that is, a range in which the repeat accuracy is sufficiently obtained), it falls within the allowable range, and Zc in this case is set as the reference position of the blade 54. However, if the read initial light amount V0 becomes lower than the predetermined value to some extent, an error occurs in step 86.

As described above, according to the blade position detecting device of the present invention, the machine self-recognizes a state change due to dirt in the optical history of the optical sensor and an unstable state due to water droplet adhesion, and follows the changing state. If the favorable conditions are not satisfied, retry or error handling can be performed. Therefore, the ambient light acting on the optical sensor and the noise generated from the optical sensor can be removed, and the sensitivity of the optical sensor can always be kept constant. As a result, the blade wear amount can be accurately measured, and the blade tip can be positioned with high accuracy.

Although the threshold value is set to the initial light amount V0 / 2 in the above embodiment, other values may be set to the threshold value. The blade position detecting device according to the present invention is configured such that the size Za of the sampling area of the condensed light flux 102 and the actually measured size Z of the light flux 102.
The difference from b is checked with | Za-Zb |, and it is confirmed whether the optical system is narrowed down to a spot diameter with which sufficient repeatability can be obtained.

[0029]

As described above, according to the blade position detecting device and the reliability determining method thereof according to the present invention, the displacement position of the rotary blade when the signal outputting means outputs the signal Set the correction position considering wear and the like. Therefore, when the wear amount of the blade changes depending on the type of work to be processed, the variation of the blade, and the amount of cut, etc., the rotary blade is in a non-contact state, that is, the tip of the rotary blade is not brought into contact with the machining table. It can be positioned with high precision.

Further, since ambient light and noise can be removed, the positioning accuracy of the blade can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a blade position detection device according to the present invention.

FIG. 2 is a diagram for explaining an operating state of each part of the blade position detecting device according to the present invention.

FIG. 3 is a perspective view showing a state where a work is processed by a dicing device provided with a blade position detection device according to the present invention.

FIG. 4 is a perspective view showing a state in which a blade of the dicing device is being detected by the blade position detecting device according to the present invention.

FIG. 5 is a flowchart illustrating an operating state of the blade position detecting device according to the present invention.

FIG. 6 is a graph showing a measurement result when the optical system of the blade position detecting device according to the present invention is free from dirt.

FIG. 7 is a graph showing the measurement results when the optical system of the blade position detecting device according to the present invention is unevenly soiled.

FIG. 8 is a graph showing a measurement result when the optical system of the blade position detecting device according to the present invention is uniformly soiled.

[Explanation of symbols]

 10 ... Blade position detecting device 16 ... Light emitting diode (light emitting means) 22, 24 ... Amplifier 23 ... Photodiode (light receiving means) 28, 32 ... Optical fiber 34, 40 ... Lens system (pair of optical systems) 36, 38 ... Prism (a pair of optical systems) 44 ... Condenser 45A ... Light amount reading means 45B ... Blade displacement reading means 47 ... Storage means 54 ... Blade (rotating blade) 74 ... Comparator 76 ... One shot

Claims (2)

[Claims] 1. An optical system, which is provided so as to face the light projecting means at a predetermined interval, collects the light projected from the light projecting means within one of the predetermined intervals by one optical system, and diffuses after the light is collected. A pair of optical systems that collect the collected light by the other optical system, a light receiving unit that receives and photoelectrically converts the light collected by the other optical system, and the disturbance light received by the light receiving unit and the generated light. A means for removing noise, a rotary blade that moves orthogonally to the optical axis between predetermined intervals of the optical system, and shields the light condensed within the predetermined intervals, and reads the amount of light received by the light receiving means. A means for reading the displacement of the rotary blade and a means for outputting a signal when the amount of light received by the light receiving means matches a preset value stored in advance, based on the displacement position of the rotary blade at the time of outputting the signal. Characterized by positioning the tip of the rotary blade with respect to the workpiece. That blade position detection device. 2. The light projecting means is provided so as to face the light projecting means at a predetermined interval, and the light projected from the light projecting means is condensed by the one optical system within the predetermined interval and diffused after the light is condensed. A pair of optical systems that collects the collected light by the other optical system, a light receiving unit that receives and photoelectrically converts the light collected by the other optical system, and the disturbance light received by the light receiving unit and the generated light. A means for removing noise, a rotary blade that moves orthogonally to the optical axis between predetermined intervals of the optical system, and shields the light condensed within the predetermined intervals, and reads the amount of light received by the light receiving means. A means for reading the displacement of the rotary blade and a means for outputting a signal when the amount of light received by the light receiving means matches a preset value stored in advance, based on the displacement position of the rotary blade when the signal is output. Blade position detector that positions the tip of the rotary blade with respect to the workpiece. In the setting, after cutting a predetermined number of works with the rotary blade, the pair of optical systems are washed, and when the rotary blade is positioned at the non-shielding position of the light condensed, the light receiving means passes through the pair of optical systems. When light is received and the received light amount V0 is substantially equal to the previously stored light amount V1 when the pair of optical systems is kept clean, the light condensed within the interval of the optical system is detected. Every time the rotary blade is moved by a predetermined amount in the light-shielding direction, the light quantity V received by the light receiving means and the displacement Z of the rotary blade are stored, and the light quantity V received by the stored light receiving means and the displacement Z of the rotary blade are stored. And a relationship between the obtained relationship and the positional relationship between the pair of optical systems in a clean state and the rotary blade is substantially matched, the pair of optical systems is determined to be clean. Of the reliability of the blade position detector Method.