JPS63253242A - Inspecting device for flaw - Google Patents

Abstract

PURPOSE:To simplify the circuit of a flaw detector by providing a temporary storage means to an inspecting circuit part and storing information on a flaw. CONSTITUTION:A stamper 16 is sucked to a turntable with air and a spindle motor 18 is rotated. Further, outputs (d) and (b) of an encoder 19 are utilized as a signal for controlling a spindle motor driving circuit 21 and knowing the generation place of a flaw. A laser driving circuit 11 drives the laser light source of an optical pickup 14 and a focus tracking savo circuit 12 focuses the light source of the optical pickup 14. The quantity of light reflected by the stamper 16 is detected by the optical pickup 14, charged and converted, and supplied to an amplifying circuit 13. A detecting circuit part has temporary storage means 37-39 for information (a) on the flaw and receives the flaw signal (a), an encoder output signal (d), and an encoder origin output signal (b) to recognize the flaw, detect the occurrence place, and recognize its size.

Description

[Detailed Description of the Invention] [Prior Art and Problems] With the development of the information society, the amount of information handled has increased significantly, and in terms of information management, there are also issues such as recording, storage, and retrieval of information. Optical disk memory is attracting attention.

Optical disk memory records or regenerates signals by shining a laser beam focused on minute pits of about 1 micron formed on the disk surface, so it is affected by scratches that occur on the surface of the optical disk. It is difficult to avoid this. Since optical disk memories often handle code information, a particularly low bit error rate is often required during signal reproduction, and scratches on the fir surface of the optical disk during the manufacturing process of the optical disk 7 must be strictly controlled.

In addition, it is necessary to similarly manage the optical disc substrate and stamper used to manufacture the optical disc. In order to inspect for scratches in such an optical disc manufacturing process, for example, as disclosed in Japanese Patent Laid-Open No. 57-94636, a video camera is attached to a microscope for inspecting the disc to be measured. Scan a fixed location on the measuring disk, input the electrical output from the running up to an analog comparator, and if the previous electrical output is equal to or higher than the required threshold level in the analog comparator, the output of the analog comparator is count the number of horizontal synchronization scan lines of the video camera that occurs, and detect defects in the disk substrate by the output from the analog comparator and the number of horizontal synchronization scan lines of the video camera that generates the output. There is a disk substrate defect inspection apparatus that is characterized by inspecting disk substrate defects. By using this defect inspection device, it is possible to easily inspect defects larger than about 10 microns. However, this defect inspection device cannot be used when it is necessary to simultaneously inspect large flaws and small flaws of about 1 micron to manage the flaws.

In addition, a defect inspection device disclosed in Japanese Patent Application Laid-Open No. 60-261044 condenses the light emitted from a light source into a minute spot light using an optical system having an aperture lens, and irradiates this minute spot light onto a track groove on a disk. A first signal means detects the reflected light from the track groove, performs focus servo e based on the detected signal, and obtains a signal corresponding to the movement of the pickup in the focus direction; The second servo circuit obtains a signal corresponding to the movement of the pickup in the tracking direction.
a signal means, a mixing means for obtaining an information signal from a signal detected from the reflected light, and any one of the outputs of the first signal means, the second signal means, and the mixing means is at a predetermined level or higher. This is an optical disk inspection device equipped with a comparator means for detecting whether or not the According to this device, disc deformation in the focus direction and tracking direction is also detected by detecting the acceleration of the disc, so in addition to disc defects caused by scratches in the track grooves of the disc, there are also Directional deformations can also be examined.

However, the main purpose of inspecting optical discs for scratches during the optical disc manufacturing process is to understand the occurrence of scratches on optical discs in each process of optical disc manufacturing, to determine the cause of scratches in each process, and to improve product yield. Therefore, it is not sufficient to simply obtain a detection signal of a scratch on an optical disc.

For example, even if a large number of scratches are detected on the surface of a single optical disc and all the scratches are displayed on a monitor TV or the like, very meaningful information will not be obtained. In order to use the scratch calibration results immediately on the production line, the information must be processed so that it can be seen with the human eye, understood immediately, and made judgments, and displayed on a display device such as a monitor TV in an easy-to-understand manner. needs to be displayed.

Further, even when simply checking the number of scratches that have occurred on the surface of an optical disk, the number of scratches cannot be determined just by counting the scratch detection signals. First, it is necessary to recognize each individual scratch, and only by recognizing the scratches can the number of scratches be counted.

In order to use a scratch inspection device in the manufacturing process of optical discs, it is desirable to be able to output the scratch information processed as described above and to visually display the scratch data. There was no testing equipment available.

[Means for solving problems]

The present inventor completed the present invention as a result of intensive research to solve the above problems.

The present invention will be explained below based on examples.

The numbers and symbols in each figure used in this embodiment are common to each figure, and may be explained without following the order of the figures. FIG. 1 is a block diagram of a flaw inspection device. FIG. 2 is a configuration diagram of the optical disc drive section. FIG. 3 shows a block diagram of the flaw detection circuit section. FIG. 4 is a timing diagram of the flaw detection circuit. FIG. 5 is a flaw recognition flowchart. 6th
The figure is a flowchart for inputting information about scratches. FIG. 7 is a flowchart of flaw recognition processing. FIG. 8 is a flowchart for calculating the area of a flaw. FIG. 9 is a diagram showing the scratch arrangement information A and the storage data of the scratch information inside the micro combinator. FIG. 10 is flaw arrangement information B, which is a diagram showing intermediate data obtained by processing the information in FIG. 9. FIG. 11 is a diagram showing the final data obtained by processing the information in FIG. 10 using scratch arrangement information C. Figure 12, 1st
3 and 14 are diagrams showing display screens when the information in FIGS. 10 and 11 is output.

In this embodiment, the optical disc drive device is composed of an optical disc drive section and a detection circuit section.

In FIG. 1, the output of an optical disk drive device 1 is supplied to an information processing means 2, and the output of the information processing means 2 is supplied to an information output stage 3.

In FIG. 2, a laser drive circuit 11 is a circuit that drives a light source such as a semiconductor radar (not shown) included in an optical pickup 14 and at the same time stabilizes the amount of light from the light source. Focus/tracking servo circuit 1
2 always uses the optical Bicara F14 condensing lens with Stanno 4
A light source such as a semiconductor laser (not shown) is focused on the surface 15, and at the same time, the light source is guided to either the group portion or the land portion. The signal amplification circuit 13 receives the amount of light reflected from the stamper 16 using an optical pickup 14, and amplifies the converted electrical signal. The optical pickup 14 includes a semiconductor radar, a lens, and a mirror.

It is composed of a light-receiving element, an actuator, etc. (not shown), and is normally used by condensing the light into a light diameter of about 1 μmφ. This spot diameter determines the size of the smallest detectable flaw. The slider motor 15 moves the optical pickup 14t in the radial direction.

In this embodiment, the test object 16 is stan t4, so it may be referred to as stannoya in the following text. Turntable 17 is Stan/411
6 is placed on the turntable 17, and the stamper 16 is rotated by air adsorption on the turntable 17. The spindle motor 18 is capable of rotating the turntable 17 and stamper 16 at high speed. The encoder 19 is used to control the spindle motor drive circuit 21 and as a signal to know where a flaw has occurred. The slider motor drive circuit 20 rotates the slider motor 15. The spindle motor drive circuit 21 is the stamper 1
6 and turntable 17 at high speed and stably. Vacuum pump f22 is turntable 17
Even if the upper stand 16 is attracted and rotated, it is held in the same state. The scratch signal a is a reflected signal obtained from the optical pickup 14, and its voltage level changes if there is a scratch. The encoder output signal d is the output of the encoder 19 and is an encoder output signal generated with the rotation of the encoder 19, which generates 1024 pulses of hp and fi1024 pulses per x rotation. The encoder origin output signal f is also the output of the encoder 19, and is an origin output pulse that generates one pulse per rotation.

The detection circuit shown in FIG. 3 receives the flaw signal a, the encoder output signal d, and the encoder origin output signal f shown in FIG.
Performs flaw recognition processing, detects the location of the occurrence, and recognizes the size. In Fig. 3, the controller 31 compares the flaw detection level of the flaw signal a and the flaw detection level signal, and when the flaw signal a exceeds the flaw detection level b, it is determined that a flaw has been detected.
k and output as a pulse waveform of a digital flaw signal C.

When the flaw detection level signal S is larger than the flaw signal a, no flaw is being detected, and at this time the digital flaw signal C does not become an output pulse. The circumferential flaw counter 32 counts based on the pulse time length of the digital flaw signal C - gt clock e. The value of this counter 32 becomes the value of the flaw size i. The multiplier circuit 33 multiplies the encoder output signal d.

The frequency dividing circuit 34 divides the frequency of the multiplied t4 pulse. The multiplier circuit 33 and frequency divider circuit 34 generate pulses of arbitrary frequencies, and the multiplier ratio and frequency division ratio are determined from the minimum flaw length (resolution) determined by the clock e. The circumferential position counter 35 calculates the circumferential position of the flaw by counting the encoder output signal d.

Further, this circumferential position counter 35 is reset by the encoder origin output signal f. The signal i is a signal of the thickness of the flaw, the signal j is a signal of the position in the circumferential direction, and the signal is a signal of the position in the radial direction. Radial position counter 3
6 determines the position of the flaw in the radial direction by counting the encoder origin output signal ft. FI that constitutes temporary storage means
FO memories 37, 38, and 39 are scratch length signals 1
Scratch position signal j in one circumferential direction, scratch position signal kt in radial direction
- It is something that is stored at the same time; the length of the wound and the information about its position are always stored as a pair of combinations. Also, F
IFO memory 37.38. By using 39 and 39, even if the subsequent processing takes time, the next signal itself will be stored continuously according to the flaw detection information time interval, so it will be sequentially retrieved according to the flaw detection information usage time interval. Subsequent processing is possible. 110f! ) 40 reads scratch data and data on the location where the scratches occur in the FIFO memories 37, 38, and 39 in order according to instructions from the microcomputer 41. timing circuit 4
2 is for writing to the FIFO memories 37, 38, and 39, e-Rus, and clearing pulses for the scratch counter 32, etc., at a fixed timing.

In this embodiment, a microcomputer 41 is used to implement the information processing means, and the microcomputer 41 classifies the size of the scratches and classifies the scratches by location according to the scratch recognition flowchart shown in FIG. Performs processing to determine the occurrence distribution. FIG. 4 is a timing diagram of the flaw detection circuit, which illustrates the temporal signal flow of the operation of the circuit described above.

The flaw recognition processing process will be explained according to the flaw recognition flowchart shown in FIG. At step 51 in FIG. 5, information on the flaw is input into an external FIFO memory or microcomputer. Details of step 51 in FIG. 5 are shown in the flaw information input flowchart in FIG.

Measurement is started in step 61 in FIG. 6th
At step 62 in the figure, it is checked whether scratch information exists in the external FIFO memory. If there is no profit information, proceed to step 66 in Fig. 6 and check whether the measurement is complete. If the measurement is not completed, step 62 in Figure 6
Go back and repeat the same action. Step 62 in Figure 6
If there is scratch information, the process advances to step 63 and the external F
The end position of the scratch, the length of the scratch, and the track position (corresponding to the radius) are read from the IFO memory. Next, the 6th
Proceeding to step 64 in the figure, the position where the scratch occurs is calculated from the end position of the scratch and the length of the scratch. At this time, if we express the end position of the scratch and the formula of the scratch in terms of rotation angle, and let θ■ and θnL respectively, the scratch occurrence position is θns”θng
-θnL. The process then proceeds to step 65 in FIG. 6, where it is stored in the computer in a format similar to the flaw arrangement information A in FIG. 9. The flaw arrangement information A shown in FIG. 9 has information such as a flaw start position, a flaw end position, a flaw length, a track position, and a flag for the number of flaws that have occurred. At this time, the initial value of the flag is set to rlJ. Steps 61, 62, 63, 64, and 65 in FIG.
A section 8 is configured to convert the hot water information read from the memory and store it in the flaw information array A in FIG. Next, the fifth
The process advances to step 52 in the flaw recognition flowchart shown in the figure. Step 52 in FIG. 5 is a means for recognizing individual flaws, that is, a process of grouping together flaw information regarding the same flaw, which will be explained with reference to the flaw recognition processing flowchart in FIG. 7. In step 67 of FIG. 7, flaw information is sequentially extracted from the top of the flaw array information A of FIG. 9 and stored in an area for comparison. At this time, the 7-lag term of the flaw arrangement information A in FIG. 9 is set to "0".

This means that this part of the information has been extracted. If it is "1", it is assumed that there is still scratch information in that part. Next, proceed to step 68 in FIG.
Compare the track positions in the flaw information stored in the area for comparison, and sequentially search for flaw information that has track position information for one track from the flaw array information A in Figure 9. To go. In Stella f69 of FIG. 7, if there is information about scratches at the adjacent track position, the process advances to step 70 of FIG. In step 70 of FIG. 7, it is checked whether the start and end positions of both scratches overlap in the scratch information located at adjacent track positions. If there is no overlapping portion, it is determined that the scratches are different, and the process returns to step 68 in FIG. 7 to search for new scratch information at the adjacent track position. In step 70 of FIG. 7, if there is an overlap between the scratch start position and end position of the scratch information on the track positions between the two, it is determined that they are the same scratch, and as shown in FIG. Proceed to step 71. In step 71 of FIG. 7, the flaw information stored in the area for comparison is transferred to the flaw array information B of FIG. 10. At this time, when only the information about the first scratch recognized as the same scratch is transferred to the scratch array information B in FIG. 10, the flag is set to "1". The meaning of this flag being "1" means the beginning of a set of information about the same flaw. Other than this, the flag is "0" until the next bath. Next, step 72 in Figure 7
As a result of the verification, the flaw information that has arrived is moved from the flaw array information A in FIG. 9 to the area for verification. At this time, similarly to step 67 in FIG. 7, the flag of the flaw arrangement information A in FIG. 9 is set to "0". Next, the process returns to step 68 in FIG. 7, and the flaw information at the track position next to the track position of the flaw information newly stored in the area for verification is transferred to the seventh track position.
Search in the process from step 68 to step 70 in the figure. 7th
If it is determined in steps 73 and 74 of the figure that the track position of the flaw information existing in the region for verification and the flaw information of the adjacent track position are not in the flaw array information A of Fig. 9, From step 74 in the figure, the process returns to step 67, and the next new wound information is moved to the area for verification. Also, at this time, from the flaw array information A shown in FIG. 9, only those whose flag content is "1" are searched. If all the flags become "0", it means that all the wound information has been known. As a result, the flaw array information B in Figure 10 shows that the same flaws are arranged in order, and the flag indicates that rlJ is the beginning of the flaw and that the area immediately before the next rlJ is the same flaw. This means that they have been rearranged as follows. The process then proceeds to step 53 in FIG. Step 53 is a step of calculating the area of the same flaw from the flaw arrangement information B shown in FIG. 10. The means for calculating this flaw area will be explained in detail with reference to the flaw area calculation flowchart of FIG. At step 75 in FIG. 8, the first scratch information t whose flag content is rlJ is read from the scratch array information B in FIG. 10. Subsequently, in step 76 of FIG. 8, since the length of the flaw at that track position is expressed as the angle θn1, it is determined by the actual formula Ln t' Ln =θml, X Rn. In this case, Rn is the radius at the track position. Subsequently, the flaw length Ln obtained in step 77 of FIG. 8 is added to the area addition buffer S. Subsequently, in step 78 of FIG. 8, the information flag 'tliJ4' for the next wound in report B is set to the number of wounds shown in FIG. 10. At this time, if the flag is "0", the same hot water continues,
Returning to step 76 in FIG. 8, the same processing tm is returned. If the flag is set to "0", it is determined that the information on the same flaw has been completed, and the process proceeds to step 79 in FIG. The value 5nt of the area addition buffer obtained in step 77 is stored. Next, in step 80 of Fig. 8, the contents of this area addition buffer are cleared, and the information of the flag "1" removed earlier is used as the leading flaw information to return to step 76 of Fig. 8. Repeat. The above processing is applied to the scratch arrangement information B in Figure 10.
By repeating the process until there is no more information, the flaw arrangement information C in FIG. 11 obtains the flaw positions and flaw areas for the number of flaws. Through the above processing, the actual number of scratches and the area of each scratch are obtained. Step 54 of the flaw recognition flowchart in FIG. 5 is to output necessary information based on the results obtained in the further processing using an information outputting means using a display device such as a monitor TV. It is a process of Figures 12, 13, and 1
The data display example in FIG. 4 is an example of the content obtained in this embodiment. FIG. 12 is a histogram of area, which is obtained from the flaw arrangement information C in FIG. 11. Figure 13 is a map display of the wound.
This can be obtained from the flaw arrangement information C in Figure 1. 14th
The figure shows an example of the shape of a scratch obtained as a result of actual measurement.1)
, which can be obtained from the flaw arrangement information B in FIG.

In this figure, tracks 81, 82, 83, 84° 85, and 86 are shown to show the shape of the scratches. The display example described above can only be obtained by recognizing each scratch and determining its area, and is a very effective means for investigating the cause of scratches on optical discs and the like.

The flaw inspection apparatus of the present invention, which has been described above using the embodiments, is an apparatus for inspecting flaws occurring on an optical disc, a substrate of an optical disc, or a stand for molding an optical disc, and includes:
■An optical disc drive device comprising: a flaw inspection circuit section including a temporary storage means for information on detected flaws; an optical disc drive section; an information processing means; and an information output means. It is. Here, the temporary storage means may be any ordinary buffer memory, but the flaw information is stored in a FIFO according to the time interval at which the flaw detection information is generated.
The circuitry of the flaw detection device is simplified by using a temporary storage means consisting of a circuit that inputs flaw detection information to a memory and outputs flaw detection information from the FIFO memory according to the flaw detection information utilization time interval. There are various information processing means used in flaw inspection devices, such as calculating the length of a flaw and calculating the position of a flaw. When displaying information that can be used immediately on a line, an information processing means consisting of a recognition means for recognizing the same flaw from information on detected flaws and a calculation means for calculating the area of each flaw is used. He invented that when used, it becomes possible to display a display that is easier to understand. The flaw recognition means that has been used in conventional inspection equipment to detect continuous and discontinuous signals of flaws in the circumferential direction and recognize them as a single flaw has detected only part and all of the true flaw. However, there is a method for extracting flaw information from flaw information array A and putting the flaw information into a collation buffer, and ■ obtaining an i blue report of flaws on the adjacent track from the track position in the collation buffer. means for searching from scratch information array A; [3] means for determining the presence or absence of scratch information at adjacent track positions; and [4] scratch start position and scratch end position for adjacent scratch information. (1) means for recognizing the same flaw and sequentially storing flaw information in the collation buffer into flaw information array B; More accurate flaw recognition has become possible for the first time by using a means for storing information in a comparison buffer and a recognition means consisting of the following. Conventional flaw inspection devices use information about the length of flaws in the circumferential direction as information about the flaw size, but ■Means for reading flaw information from flaw information array B; [3] For each flaw, calculate the area of one flaw by adding all the actual flaw lengths related to one flaw. means and ■
By using a means for storing information on the area of the scratch in the scratch information array C and a calculation means for calculating the area of each scratch, it has become possible to grasp the area of the scratch more accurately. With conventional flaw inspection devices, the flaw information obtained is simply output as text information using an output device such as a printer, so it takes a long time to analyze that information.
■Means for selecting one flaw with a designated formula from each recognized flaw, and ■Means for selecting one flaw with a designated formula from among each recognized flaw, and ■Selecting all circumferential position information and essential circumferential formula for one selected flaw. Information output consisting of means for calculating coordinates representing the shape of the flaw from the information and information on the position in the radial direction, and means for displaying the coordinates representing the shape of the flaw on a display device that defines the coordinate axes. means, and ■ means for reading wound area information; ■ means for inputting a plurality of boundary values for classifying wound area information by area dog@o; ■ wound area information; A means for classifying information on the wound area by sequentially comparing the boundary values of and a means for counting the number of wound area information classified as 0 for each classification; and a means for displaying information on the area of scratches corresponding to this interval as a histogram on a display device. A visual display that is easy to judge immediately by looking at it becomes possible.

The embodiments described in this specification are merely examples. Further, it goes without saying that specifications or design changes can be made within the scope of the purpose of the present invention, including the constituent elements of the present invention.

〔Effect of the invention〕

The device of the present invention makes it possible to detect scratches on optical discs, their substrates, or stampers from a diameter of around 1 μm, and also makes it possible to classify the size of the scratches and measure their distribution in location. By obtaining the distribution of scratches that occur sequentially from scratch to stamper for each process, it is possible to provide a very effective means for identifying the cause of the scratches based on the occurrence situation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the flaw inspection device of this embodiment.
FIG. 2 is a configuration diagram of the optical disc drive section. FIG. 3 is a block diagram of the flaw detection circuit section. FIG. 4 is a timing diagram of the flaw detection circuit. FIG. 5 is a flaw recognition flowchart. FIG. 6 is a flowchart for inputting information on flaws, and is a detailed flowchart of step 51 in FIG. FIG. 7 is a flowchart of the flaw recognition process, and is a detailed flowchart of step 52 in FIG. FIG. 8 is a flowchart for calculating the area of a flaw, and is a detailed flowchart of step 53 in FIG. FIG. 9 is the flaw arrangement information A, which is a diagram showing the data stored in the flaw information inside the microcombier. 1st O
The figure shows flaw arrangement information B, which is intermediate data obtained by processing the information in FIG. 9. FIG. 11 is a diagram showing the final data obtained by processing the information in FIG. 10 using scratch arrangement information C. This diagram is organized in the form of a pair of locations and scratch areas. FIGS. 12, 13, and 14 are diagrams showing display screens when the information shown in FIGS. 10 and 11 is output.

Claims (7)

[Claims] (1) A device for inspecting scratches occurring on an optical disk, an optical disk substrate, or a stamper for molding an optical disk, which comprises: [1] A flaw detection circuit section including temporary storage means for information on detected flaws; and an optical disk drive. A flaw inspection device comprising: an optical disc drive device comprising: [2] an information processing means; and [3] an information output means. (2) The temporary storage means consists of a circuit that inputs the flaw information into the FIFO memory according to the flaw detection information generation time interval and outputs the flaw detection information from the FIFO memory according to the flaw detection information usage time interval. The flaw inspection device according to item 1, characterized in that: (3) The information processing means for detecting scratches according to paragraph 1, characterized in that the information processing means includes a recognition means for recognizing the same scratch from information on the detected scratches, and a calculation means for calculating the area of each scratch. Inspection equipment. (4) The recognition means includes: [1] means for extracting flaw information from the flaw information array A and putting the flaw information into a collation buffer; and [2] means for extracting flaw information from the flaw information array A and inputting the flaw information into a collation buffer; means for searching flaw information from flaw information array A; [3] means for determining the presence or absence of flaw information at adjacent track positions; and [4] a flaw starting position and flaw information for adjacent flaw information. [5] means for recognizing the same flaw and sequentially storing flaw information in the collation buffer into flaw information array B; 2. The flaw inspection device according to claim 1, comprising: means for storing flaw information from the information array A into a collation buffer; (5) The calculation means for calculating the area of each scratch consists of [1] means for reading the scratch information from the scratch information array B, and [2] calculating the actual length of the scratch from the read scratch information. [3] For each flaw, means for calculating the area of one flaw by adding the lengths of all the actual flaws related to one flaw; [4] Means for calculating the area of one flaw by adding the lengths of all actual flaws related to one flaw; 2. The flaw inspection device according to claim 1, comprising: means for storing flaw information in the flaw information array C; (6) The information output means includes: [1] means for selecting one specified flaw from among each recognized flaw, and [2] means for selecting one specified flaw from each of the recognized flaws, and [2] all circumferential direction information regarding the selected one flaw. means for calculating coordinates representing the shape of a flaw from position information, circumferential length information, and radial position information; [3] displaying the flaw shape on a display device that defines coordinate axes 2. The flaw inspection device according to claim 1, further comprising means for displaying coordinates representing: and means for displaying a flaw shape consisting of: (7) The information output means includes: [1] a means for reading information on the area of the wound; [2] a means for inputting a plurality of boundary values for classifying the information on the area of the wound by area size; [3] A means for sequentially comparing the wound area information and a plurality of boundary values to classify the wound area information; [4] A means for classifying the wound area information by sequentially comparing the wound area information and a plurality of boundary values; [5] Means for displaying an interval divided by a plurality of boundary values and the number of scar area information corresponding to this interval as a histogram on a display device. The flaw inspection device according to item 1.