JPH063279A - Method and device for inspecting hard disc or wafer - Google Patents

Abstract

PURPOSE:To detect gradation difference of light by emitting point source light and parallels light to a hard disc or wafer, reflecting the lights thereby, and photographing the reflected light or scattered light by a CCD sensor camera. CONSTITUTION:The light generated from an xenon light source 1 is converged by a lens 2 and passed through a pinhole 3, thereby forming a point source light 4. The linear light 4 is reflected by a reflecting mirror 5 and then emitted to the whole body of a hard disc 6 with an incident angle of 30 deg. in the center part. Since the disc 6 has a high resolution encoder, the disc 6 can be rotated at a fixed speed. The light emitted to the disc 6 forms a reflected light 7, and only the reflected light on the radius of the reflected light from the disc 6 is photographed by a CCD line sensor camera, and detected by a CCD line sensor 8 built in the CCD line sensor camera. Thus, a defective part such as a dent or small projection of the hard disc 6 can be inspected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a hard disk or a wafer, which is capable of efficiently inspecting defects such as scratches, pinholes, dents and small projections on a hard disk or a wafer. It relates to a device capable of carrying out the method.

[0002]

2. Description of the Related Art In recent years, with the development of personal computers and the like, the amount of hard disks used in personal computers has increased. The hard disk is made by applying a magnetic material to the surface of a metal disk made of an aluminum alloy, and can be rotated at a high speed for writing and reading with a magnetic head. By the way, these hard disks have scratches, pinholes, dents, small protrusions,
Defects such as stains may occur. Inspection of the hard disk is extremely important because these defects significantly impair the performance of the hard disk. However, conventionally, the inspection of this hard disk utilizes the distortion of the image of a fluorescent lamp or the like to inspect the unevenness of the surface, or a method of visually inspecting the image by applying a point light source to an object. However, there are drawbacks such that it takes time and labor, the efficiency is extremely low, and small defects cannot be inspected. On the other hand, with the development of electronic technology in recent years, miniaturization and high performance of wafers are being pursued. Such wafers will suffer a significant loss of performance even with small surface defects. Conventionally, the wafer inspection has been performed in the same manner as the hard disk inspection, and no efficient inspection method has been proposed. Therefore, an efficient method for inspecting hard disks or wafers is a big issue,
There has been a long-felt need for an efficient method of inspecting a hard disk or wafer that can detect even small defects.

[0003]

SUMMARY OF THE INVENTION In view of the problems of the conventional method for inspecting a hard disk or wafer, the present invention provides a scratch, pinhole,
The object of the present invention is to provide a method for inspecting a hard disk or a wafer that can inspect defective portions such as dents and small protrusions quickly, efficiently, and accurately, and an inspection apparatus that can implement the method. It is a thing.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventor has found that when linear light from a point light source hits a hard disk or a wafer and is reflected, for example, reflection of reflected light from a dent portion. Since the angle is different from the angle of reflection from the normal part, the light intensity of a part of the reflected light becomes large, and the light intensity of the other part becomes small, so that the intensity of the reflected light becomes uneven and the reflected light is bright. We found that there are dark and light areas, but we found that the bright and dark areas can be detected by identifying them with a CCD sensor camera, and when parallel light is irradiated on a hard disk or wafer with defective areas such as scratches, a point light source. It was found that the bright and dark parts that occur in the same manner as the linear light due to can be identified and detected by the CCD sensor camera. And we have completed the present invention found that a defective portion of the wafer can be efficiently examined. That is, according to the present invention, the point light source and the parallel light are applied to the hard disk or the wafer to be reflected, and the reflected light or the scattered light is separately photographed by the CCD sensor camera, and the gradation difference of the light is detected. A method for inspecting a characteristic hard disk or wafer is provided. The present invention also provides an inspection light source including a light source that emits point light and a light source that emits parallel light, a CCD sensor camera capable of capturing reflected light or scattered light from a hard disk or a wafer, and It is an object of the present invention to provide an inspection apparatus for a hard disk or a wafer, which has a detection means capable of detecting a gradation difference.

The present invention will be described in detail below. The method for inspecting a hard disk or a wafer according to the present invention requires that the point light source and the parallel light are applied to the hard disk or the wafer to be reflected. The linear light from the point light source can accurately inspect defects such as dents and small protrusions on the hard disk or wafer. In addition, the reflected light and the scattered light due to the parallel light can be used to inspect defective portions such as scratches, pinholes, and stains on the hard disk or wafer. The light from the point light source and the parallel light may be irradiated onto the hard disk or the wafer at the same time, or may be sequentially irradiated separately. When the hard disk or the wafer is sequentially irradiated with the point light source and the parallel light, the order of application is not particularly limited and may be appropriately selected. That is, light of either point light source or parallel light is applied to the area of the hard disk or wafer to be inspected, reflected, and the reflected light or scattered light is detected to inspect the hard disk or wafer, and then it is applied first. The hard disk or wafer may be inspected by stopping the irradiation of light and irradiating the other light to reflect it, and detecting the reflected light or scattered light. As the point light source light, for example, a point light source may be used as it is, or a point light source having a smaller diameter can be obtained by applying it to a pinhole. On the other hand, collimated light can be obtained, for example, by guiding light from a light source through an optical fiber.

The light source for generating the point light source and the parallel light is not particularly limited and various light sources can be used, but a xenon light source, a mercury lamp, a halogen lamp, a metal halide lamp and the like are preferable. The point light source light can be obtained by placing a pinhole in front of these light sources and letting the light emitted from the light source pass through the pinhole. On the other hand, collimated light can be obtained by various means, for example by placing slits in front of these light sources and by glass fibers. The intensity of the point light source light and the parallel light is not particularly limited, and the CC used
The strength should be adjusted to the sensitivity of the D sensor. If the intensity of the point light source and the parallel light is too large, the defect that the signal is saturated is likely to occur, and if the intensity is too small, the sensitivity is likely to be deteriorated. The point light source and the parallel light may be directly irradiated with the light from the light source on the hard disk or the wafer, or the light from the light source may be reflected by a reflection mirror or the like and the reflected light may be irradiated. In the latter case, since the device can be downsized,
preferable. Further, the incident angles of the point light source light and the parallel light are not particularly limited and may be appropriately selected usually in the range of 0 to 90 °, but are preferably in the range of 10 to 80 °. The range of irradiation with the point light source light and the parallel light is not particularly limited, and may be applied to a part or the whole of the range to be inspected on the hard disk or the wafer.

In the present invention, the point light source or the parallel light from the light source is reflected on the hard disk or wafer surface,
It is necessary to separately capture each reflected light or scattered light with a CCD sensor camera having a built-in CCD (charge coupled device) sensor. The CCD sensor includes a CCD line sensor and a CCD area sensor, both of which can be applied to the present invention, but in the present invention, C
A CD line sensor is preferred. The CCD line sensor has the advantages that it can detect with high resolution and that high-speed processing is easy. The CCD line sensor is one in which a large number of image elements are arrayed, and the number of the image elements is usually in a linear range of 100 to 10,000, preferably 512 to 10,000. When the CCD line sensor detects the size, the size of the defective portion can also be detected. Further, the width of the image to be photographed at one time is not particularly limited, and may be appropriately selected and determined depending on the size of the inspection range of the hard disk or wafer, the magnification of the portion to be photographed, the number of image elements, and the like.

In the present invention, when detecting a hard disk or a wafer with a CCD line sensor camera, the whole is detected by moving on the hard disk or the wafer. In this case, the hard disk or wafer may be moved to inspect the entire hard disk or wafer, and the hard disk or wafer may be fixed and C
The CD line sensor camera may be moved to inspect the entire hard disk or wafer, or both the hard disk or wafer and the CCD line sensor camera may be moved. The movement form of the hard disk, wafer or CCD line sensor camera is not particularly limited and may be appropriately selected and determined. For example, various movements such as linear movement, curved movement, and rotation around the center point may be performed. Although the moving form can be adopted, when inspecting a hard disk, a method of fixing the CCD sensor camera and rotating the hard disk is preferable.
It is not preferable to detect the CCD line sensor camera while rotating the wafer because it is difficult to inspect the vicinity of the rotation axis.

Further, when the hard disk or wafer is rotated, it is preferable to strictly control the rotation accuracy of the spindle, surface wobbling, eccentricity and the like. As a method for controlling the rotation of the hard disk or wafer, a method using an encoder is preferable. These movements are preferably performed by means that can be performed automatically. In the present invention, the reflected light or the scattered light of the point light source light and the parallel light is separately photographed by a CCD sensor camera having a built-in CCD (charge coupled device) sensor. When irradiating point light and parallel light at the same time, CC
Two or more D sensor cameras are provided, and each C
Can be taken with a CD sensor camera. Further, when the point light source and the parallel light are sequentially emitted, one CCD sensor camera may be sequentially photographed or another CCD sensor camera may be separately photographed. When inspecting with a CCD line sensor camera while moving a hard disk or a wafer, a point light source light is applied to a part of the hard disk or wafer, and the reflected light is detected, and at the same time, a parallel light is applied to another part to reflect the reflected light or Detecting scattered light is preferable because point light and parallel light can be inspected at the same time.

Reflected light or scattered light taken by a CCD sensor camera may be processed by directing light from a hard disk or a wafer to a sensor directly, or by collecting light by a field lens to obtain reflected light through an objective lens. Light or scattered light may be used. It should be noted that in the case where the uneven defect portion is large, the resolution is not required so much, and thus the latter method is preferable because the range in which one pixel of the sensor can be seen can be increased. In the present invention, it is necessary to distinguish reflected light or scattered light captured by a CCD sensor camera into a bright portion and a dark portion, and detect a gradation difference of the light. CC
For the reflected or scattered light captured by the D-sensor camera,
There are bright and dark areas. That is, when point light or parallel light hits a hard disk or a wafer and is reflected,
For example, the reflection angle of the reflected light from the dent portion is different from the reflection angle from the normal portion, so that the light intensity of a part of the reflected light increases,
In addition, the light intensity of the other part becomes small, which causes unevenness in the intensity of the reflected light, resulting in a bright portion and a dark portion in the reflected light. In the present invention, it is preferable to detect the bright portion and the dark portion of the reflected light or the scattered light by the pixels of the CCD line sensor.

A method for distinguishing between a bright part and a dark part is as follows:
Various methods can be adopted. For example, an image element in which the intensity of reflected light or scattered light from a normal portion of a hard disk or a wafer is set as a reference intensity and a light intensity having a predetermined amount of deviation from the reference intensity is detected. To distinguish between CC
For example, a method of distinguishing a bright portion from a dark portion each time the light intensity of an image element adjacent to the D line sensor is different can be mentioned. In addition, the magnitude of the predetermined amount of deviation can be set arbitrarily. When the reflected light or scattered light from the normal portion of the hard disk or wafer is used as the reference intensity, the average value of the reflected light or scattered light intensity obtained by inspecting the entire hard disk or wafer with few defective portions is the hard disk. Alternatively, since there is almost no difference from the intensity of the reflected light or scattered light from the normal portion of the wafer, its average value may be used as the reference intensity.

When the reference intensity is set, it is possible to distinguish and recognize both the high intensity region and the low intensity region where the light intensity is larger than the reference intensity. The high-strength area and the low-strength area can be further divided into appropriate ranges for distinction. Further, in the present invention, the reflected light in the high intensity area and the light in the low intensity area may be detected at the same time. The detection data can be image processed. The image processing includes, for example, displaying the surface of a hard disk or a wafer on a monitor screen, converting the defective portion of the hard disk or the wafer into a numerical value, and displaying the numerical value. By projecting the surface of the hard disk or wafer on the monitor screen, the size and position of the defective portion of the hard disk or wafer can be easily known.

In the present invention, it is preferable to add corrections such as illuminance correction and brightness correction and a labeling function during image processing, so that the defective portion can be detected more accurately. Here, the illuminance correction is to uniformly illuminate a certain area, lens aberration, C
It is to eliminate the illuminance unevenness due to the variation between the odd number and the even number of the CD line sensor by calculation. Brightness correction means, for example, when the reflection angle of light changes due to surface wobbling during rotation of the hard disk or wafer, eccentricity, etc.
It is to correct the change of the total light quantity. In addition, the labeling function is a function of determining whether the defective portions are a lump or scattered and accurately calculating the area. Further, the present invention can be controlled by a computer to detect a defective portion. The control by the computer can be performed by various programs, and examples of the programs include the program shown in the flowchart in FIG.

Next, the hard disk or wafer inspection apparatus of the present invention will be described. Since it has the same structure as the hard disk or wafer inspection method described above,
Portions having different configurations will be described. The hard disk or wafer inspection apparatus of the present invention needs to have an inspection light source including a light source that emits point light and a light source that emits parallel light. The inspection device for a hard disk or wafer is preferably equipped with an automatic switching device when both the point light source and the parallel light source are sequentially turned on separately. By setting the switching timing in advance in this automatic switching device, the hard disk or wafer can be inspected more efficiently. The hard disk or wafer inspection device of the present invention is equipped with a CCD sensor camera capable of photographing reflected light from the hard disk or wafer. The arrangement of the CCD sensor camera may be appropriately determined according to the desired resolution.

[0015]

According to the hard disk or wafer inspection apparatus of the present invention, first, at least one of a point light source and a parallel light source is turned on, and the light is applied to the hard disk or wafer. Then, the light is reflected by the surface of the hard disk or wafer, and the reflected light or scattered light is photographed by a CCD sensor camera. Then, the reflected light or the scattered light that has been imaged is separately detected by the detection unit into a bright portion and a dark portion. Then, after inspecting with either one of the lights, the other one of the lights is similarly irradiated to perform the same inspection. With these procedures, the hard disk or wafer inspection apparatus of the present invention can efficiently inspect the hard disk or wafer. In the present invention, the defect portion of the hard disk or the wafer can be inspected by being detected by a CCD sensor or the like built in the camera and sending the received light intensity signal to a computer for data processing.
As a result, the hard disk or wafer inspection method of the present invention can be automated. Further, the hard disk or the wafer is sent to the hard disk or wafer detection device, the hard disk or the wafer is scanned at the detection location, the automatic selection is performed when there is a defect of a predetermined value or more, the hard disk or the wafer after the inspection is completed. It can be completely automated by means of automatic delivery from the sensing location.

[0016]

An embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these examples. FIG. 1 is a schematic diagram showing an example of a hard disk inspection method of the present invention. The light emitted from the xenon light source 1 is condensed by the lens 2 and passes through the pinhole 3 to become the point light source light 4. The linear light 4 is reflected by the reflection mirror 5, and then the central portion is applied to the entire hard disk 6 at an incident angle of 30 °.
The hard disk 6 is rotated by a rotation driving device having a high resolution encoder (not shown). Since the high resolution encoder is provided, the hard disk 6 can be rotated at a constant speed, so that the inspection can be performed accurately.

The light applied to the hard disk 6 is reflected to become the reflected light 7, and only the reflected light on the radial line of the reflected light from the hard disk is photographed by the CCD line sensor camera and is built in the CCD line sensor camera. It is detected by the CCD line sensor 8. This CCD
In the line sensor 8, 2048 or 5000 image elements are arranged in series. The entire hard disk 6 can be inspected by sequentially rotating the hard disk 6. The detected reflected light 7 is detected by a light intensity detection unit (not shown) by distinguishing bright and dark portions. At this time,
The distinction between the bright and dark parts is made by inspecting the entire hard disk in advance and setting the average value of the entire intensity of the reflected light as a reference value, and the reflected light having a light intensity deviating from the reference value by 5 to 10% is determined. It was detected for each image element of the CCD line sensor.
Further, the measured received light intensity can be processed by a data processing unit (not shown) for image processing. With this method, it was possible to inspect defective portions such as dents and small protrusions on the hard disk 6.

Next, the irradiation of the point light source light 4 is stopped, and similarly to the irradiation of the point light source light, parallel light (not shown) is applied to the hard disk to be reflected, and the reflected light is detected by the CCD line sensor camera. , The whole hard disk was scanned and inspected. At this time, the distinction between the bright part and the dark part is made by inspecting the entire hard disk in advance and setting the average value of the total intensity of the reflected light as a reference value, and the reflected light with the light intensity deviating from the reference value by% is set. It was detected for each image element of the CCD line sensor. As a result, defects such as scratches and pinholes on the hard disk could be inspected. As a result, the defective portion of the hard disk could be detected automatically. FIG. 2 is a schematic diagram of a method in which the reflected light 7 is condensed by the filled lens 9, further reduced by 65% by the objective lens 10, and the light is detected by the CCD line sensor 8 in the inspection method of FIG. is there. As a result, the resolution can be reduced.

FIG. 3 is a schematic view showing an example in which the hard disk is simultaneously irradiated with point source light and parallel light in the inspection method of FIG. The reflected light of the point light source is CC as in FIG.
The parallel light 12 detected by the D line sensor 8 and emitted from the parallel light source 11 is applied to the hard disk 6 and reflected by the surface of the hard disk 6, and the reflected light 1
3 passes through the objective lens 14 and CCD line sensor 15
Detected by. Also, in some cases, the scattered light is not reflected at the same angle as the incident angle of the parallel light but slightly shifted to
It may be detected by the CD line sensor 15. This method is preferable because the hard disk can be inspected efficiently by irradiating point light and parallel light at the same time. FIG. 4 is a schematic view showing an example of a hard disk inspection apparatus according to the present invention.

In the figure, a point light source 16 including a xenon light source 1 is provided. The angle of incidence on the hard disk 6 can be changed by adjusting the angle of the reflecting mirror with an angle adjusting tool (not shown). Further, the heights of the light source 16 and the reflection mirror are adjusted by the height adjusting tool 22.
Therefore, the height can be appropriately selected. The hard disk 6 is mounted on an automatic rotary hard disk mounting table 18, is rotated at a constant speed and high precision by an encoder (not shown), and the direct drive system is used to minimize surface wobbling and eccentricity. is there. The automatic rotation type hard disk mount 18 is rotationally driven by an automatic drive motor. On the other hand, a CCD line sensor camera 17 capable of photographing reflected light or scattered light from the hard disk 6 is used for photographing. CC
The angle of the D-line sensor camera 17 can be appropriately adjusted by an angle adjusting tool (not shown). Note that C
The reflected light detected by the CD line sensor can be directly viewed by an eyepiece lens (not shown).

[0021]

According to the method of inspecting a hard disk or a wafer of the present invention, it is not necessary to manually inspect, and a defective portion of a hard disk or a wafer can be inspected efficiently. Therefore, the hard disk or wafer inspection method and apparatus of the present invention are extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a hard disk inspection method of the present invention.

FIG. 2 is a schematic view showing an example of a hard disk inspection method of the present invention.

FIG. 3 is a schematic view showing an example of a hard disk inspection method of the present invention.

FIG. 4 is a schematic diagram showing an example of a hard disk inspection device of the present invention.

FIG. 5 is a flow chart of a program for controlling the hard disk inspection device of the present invention by a computer.

[Explanation of symbols]

 1 xenon light source 2 lens 3 pinhole 4 point light source 5 reflection mirror 6 hard disk 7 reflected light 8 CCD line sensor 9 field lens 10 objective lens 11 parallel light source 12 parallel light 13 reflected light 14 objective lens 15 CCD line sensor 16 point light source Light source 17 CCD line sensor camera 18 Hard disk mount

Claims (6)

[Claims] 1. A point light source and a parallel light are applied to a hard disk or a wafer to be reflected, and the reflected light or the scattered light is separately photographed by a CCD sensor camera, and the gradation difference of the light is detected. Hard disk or wafer inspection method. 2. The method for inspecting a hard disk or a wafer according to claim 1, wherein the detected data is image-processed. 3. The method for inspecting a hard disk according to claim 1, wherein the point light source and the parallel light are applied to the hard disk separately while sequentially rotating the hard disk. 4. An inspection light source comprising a light source for generating point light and a light source for generating parallel light, a CCD sensor camera capable of photographing reflected light or scattered light from a hard disk or a wafer, and a floor of the light. An inspection apparatus for a hard disk or a wafer, comprising a detection means capable of detecting a difference in tone. 5. The inspection apparatus for a hard disk or a wafer according to claim 4, further comprising image processing means capable of image-processing the detection data detected by the detection means. 6. The inspection apparatus for a hard disk or a wafer according to claim 4, further comprising an encoder capable of controlling the rotation of the hard disk or the wafer.