JP3372224B2 - Surface inspection apparatus, surface inspection method, and recording medium recording surface inspection program - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface inspection device for inspecting the surface shape of a sample, a surface inspection method, and a recording medium recording a surface inspection program.

[0002]

2. Description of the Related Art In semiconductor wear, optical disks, magnetic disks and the like, the surface shape greatly affects the quality of products.
In particular, in a hard disk (HDD) in which a magnetic material is applied to a glass or aluminum disk, data is read and recorded while the magnetic head is levitating from the disk surface by about several tens of nm, so that the surface has a sharp uneven portion. If there is, there is a possibility that the magnetic head collides with the disk and crashes, or that reading / recording of data cannot be performed. In this case, it is important to know the flatness of the entire surface and at the same time measure abrupt shape change.

Further, a sudden change in shape is likely to appear at the edge portion in the manufacturing process of the disk. The surface shape near the edge is a roll-off (hereinafter, R
"O") and a ski jump (hereinafter referred to as "SJ") indicating the degree of swelling of the edge portion.

Conventionally, as a technique for measuring the surface shape of such a sample, a probe type inspection device and a non-contact type inspection device using a capacitance probe or the like are known. The stylus type inspection apparatus scans the sample in one direction with the needle in direct contact with the sample surface, and measures the surface shape from the vertical movement of the needle.
In the non-contact type inspection apparatus, the surface shape is measured by similarly scanning the probe in one direction and detecting the distance between the probe and the sample surface.

[0005]

However, in the above-described inspection apparatus, it is necessary to scan the needle and the probe at the time of inspection, so that only one cross section can be inspected for one scanning measurement. Inspection time becomes longer. Therefore, at most, only about 8 cross sections in the radial direction were inspected, and the other than the inspected cross section was left uninspected, and there was a possibility of overlooking the defective portion.

Further, in the stylus type inspection apparatus, since the measurement is carried out by contacting the sample surface, the sample surface may be scratched.

Further, since it is troublesome to perform such surface shape measurement and overall flatness measurement by different inspection devices, it is desired to perform them at the same time.

In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a surface inspection apparatus capable of easily inspecting a sharp shape change over the entire surface of a sample, particularly an edge part shape change.

[0009]

In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) Table for inspecting surface shape of disk
In the surface inspection device, an interference fringe interference method, an interference fringe forming means for sequentially forming interference fringes by the light reflected on the disk surface and the reference surface by changing the phase, and an image acquisition means for capturing images of the interference fringes having different phases And with the flatness analysis
And a flatness analyzer that displays the data in a predetermined format.
This is the area in the radial direction of the disk, where sudden shape changes occur.
Inspection area of the edge part that is easy to bend , inspection outside the inspection area
Setting means for setting a near region of a small section that is close to the region and is not affected by the total deflection, and a reference gland of the desired radial cross section based on the three-dimensional shape data in the neighboring region. Then, the analysis means for obtaining the displacement amount in the cross-sectional direction of the inspection region with respect to the reference gland and the analysis result by the analysis means are output , and based on the analysis result and the three-dimensional shape data.
Outputs the correspondence with the flatness analysis result including edges
And an output unit that operates.

(2) In the surface inspection apparatus of (1) ,
The inspection area is a roll-off or ski jump inspection area.
And the correspondence between the analysis results and the flatness analysis results.
Is characterized in that it is obtained by displaying a mark at the position indicating the maximum value of the maximum value or ski jump rolloff obtained by said analyzing means analyzing diagram of flatness.

(3) In the surface inspection apparatus of (1),
The inspection area is a roll-off or ski jump inspection area.
And the correspondence between the analysis results and the flatness analysis results.
By displaying the distribution of the portion satisfies a condition set from among the data of the roll-off or ski jump obtained by said analyzing means analyzing diagram of flatness
It is characterized by being obtained .

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a main part of a surface inspection device. In the following description, the case where a glass or aluminum disk used for an HDD is used as a measurement sample will be described.

The laser light emitted from the He-Ne laser light source 1, which is the measurement light source, passes through the expander lens 2 and
The collimator lens 3 collimates the light beam and makes it enter the prism 4. The reference surface 4 ′ of the prism 4 is changed in distance from the measured surface 6 ′ of the disk 6 by the piezo element 5, and the phase of the reference light is changed.

Part of the light incident on the prism 4 is transmitted through the reference surface 4 ', reflected by the surface 6'to be measured of the disk 6 mounted on the mounting table 7, passes through the prism 4 again, and passes through the screen 8'. Head to. On the other hand, of the light incident on the prism 4, the light reflected on the reference surface 4'is directed to the screen 8 and causes an interference phenomenon with the light reflected on the surface 6'to be measured, so that the screen 8 '
Projected on.

The interference fringes projected on the screen 8 are imaged by the lens 9 on the image pickup surface of the camera 10. The picked-up interference fringes are transmitted to the analysis device 11 as a video signal, and various calculation analyzes are performed. The analysis device 11 is connected to an input unit 11a such as a keyboard and a mouse, and a monitor 12 that displays captured images and analysis results. A control unit 13 controls the driving of the laser light source 1, the piezo element 5, and the like.

The operation of the surface inspection apparatus having the above structure will be described below with reference to the flowchart of FIG.

After mounting the disk 6 on the mounting table 7, it is placed at a predetermined measuring position. Laser light is emitted from the laser light source 1 under the control of the control unit 13, and the reference surface 4'and the measured surface 6 '
The interference fringes formed by the light reflected by the screen 8
Projected on. The control unit 13 also applies a voltage to the piezo element 5 to change the distance between the reference surface 4'and the measured surface 6 ', thereby changing the phase of the interference fringes. The interference fringe image with the phase thus changed is captured by the camera 10, and each image data is taken into the memory in the analysis device 11.
In the phase shift interferometry, the number of phase shifts is usually 4 steps or more.

The analyzing device 11 performs a well-known process such as noise removal on a plurality of interference fringe images having different phases stored in the memory and then determines a disk area based on the amplitude obtained by the phase shift analysis. The phases are joined to each other. Then, by converting this phase data into height data, the surface three-dimensional shape of the measured surface 6'is calculated.
For details of the analysis by the phase shift method, refer to Japanese Patent Application Laid-Open No. 10-221033 by the present applicant. The calculated three-dimensional shape is displayed on the monitor 12 in a bird's-eye view or a contour map, and the examiner can evaluate the flatness of the entire surface 6'to be measured.

Next, the case of evaluating SJ / RO will be described. The SJ / RO measurement items displayed on the monitor 12 are selected by the input unit 11a, and the radial positions r1 and r2 for creating the measurement reference line in the radial cross section and the SJ / RO are selected as input of the measurement conditions. Input the radial positions r3 and r4 of the inspection area. r1, r2, r3 and r4 indicate the distances from the center of the disc. For example, in the measurement of SJ / RO of the outer peripheral edge portion, r4 is set to the outermost periphery and r3 is set to 3 mm inward. r1 and r2 are neighboring areas that are close to each other between the inspection areas r3 and r4, r2 is at the same distance as r3, and r1 is located 4 mm inward from r2.
Note that these r1, r2, r3, and r4 may be previously incorporated into the program as fixed values, and the numerical values may be changed only when inspecting an arbitrary position.

By inputting this condition, the SJ / RO is analyzed. Below, based on the schematic diagram of the cross-sectional shape of FIG.
The RO analysis will be described. First, the measurement start angle θ
For the cross section at 1, the reference line L connecting the surface shape positions h1 and h2 at the radial positions r1 and r2 is obtained. The reference line L serves as a reference for SJ / RO calculation in the cross section in the disk radial direction, and the convex side displacement amount with respect to the reference line L is obtained as an SJ value and the concave side displacement amount with respect to the reference line L is obtained as an RO value. If the surface of the disk changes gently, the magnetic head can follow it, but if the surface changes suddenly, the magnetic head and the disk will crash or data will not be read or recorded. Therefore, r1, r that creates the reference line L
By taking 2 in the vicinity of the inspection areas r3 to r4 and in a small section according to the tracking characteristics of the magnetic head, it is possible to measure the degree of abrupt change of the inspection area without being affected by the deflection of the entire disk. it can. Further, the reference line L may be obtained as a least squares straight line between h1 and h2.

Next, the difference (displacement amount) Δh in the surface shape with respect to the reference line L is determined between the inspection areas r3 to r4.
After sequentially calculating the deviation amount Δh in the region of r3 to r4, Δh _max that becomes the maximum value of the SJ value and the RO value in this cross section
(Plus the maximum value) and Δh _{m in} (the maximum value of minus)
Be SJ ₁ and RO ₁ , respectively, and SJ _max and RO _max , respectively.
Memorize as.

SJ _max (S
Once J ₁ ) and RO _max (RO ₁ ) have been calculated, the following angle θ
After the cross-section information of No. 2 is extracted and the reference line L is calculated by r1 and r2 in the cross-section, Δh _max and Δh _min are calculated in the same manner as above, and they are SJ ₂ and RO ₂ , respectively. And S
Compare J ₂ and RO ₂ with the previously stored SJ _max and RO _max ,
The larger value is updated and stored as SJ _max and RO _max .

Hereinafter, the angle θ for extracting the cross section information is sequentially changed, the SJ value and the RO value are calculated for the cross section at each angle, and SJ _max and RO _max are compared and updated to obtain the SJ _max for the entire circumference. And RO _max . In this way, by performing analysis based on the three-dimensional surface shape data obtained from the interferometer, it is possible to easily perform SJ on the entire surface of the sample.
_{The max} value and the RO _max value can be obtained.

The angle of the cross section to be analyzed may be set at a predetermined angle (for example, every 1 degree), but in the present embodiment, for each pixel in which the outer end portion EO exists, the pixel and the disk center O. The straight line connecting with is used as the measurement cross section for analysis.

Thus, SJ _max and RO _max for the entire circumference
4A is displayed on the screen of the monitor 12 when is analyzed.
And as shown in (b), the cross-sectional shape of each cross-section having SJ _max and RO _max is displayed. The angle θ, SJ _max value, RO _max value, etc. of each cross-sectional shape are displayed on each display. The positions having the SJ _max value and RO _max value of each cross section are marked 2 respectively.
Indicated by 0a, 20b. In the display of the cross-sectional shapes of FIGS. 4A and 4B, the horizontal reference of the vertical axis (position 0) is based on the virtual plane obtained by the least square method based on all the data of the sample surface shape. it's shown.

As shown in FIG. 5, the position of SJ _max is indicated by the mark 31a and the position of RO _max is indicated by the mark 31b on the contour diagram 30 displayed as the flatness analysis result.

With respect to the results analyzed in this way,
If you specify the desired angle with the input section 11a,
Cross-sectional shape at an angle θ specified by the device 11,
SJ _maxValue, RO_maxThe value is calculated and the result at any angle is
It is displayed on the monitor 12.

As the analysis result, various changes can be made as follows. For example, if the SJ value or RO value is 0.1
When it is desired to know the portion of μm or more, the condition is input so that the distribution state is displayed on the contour diagram 30 shown in FIG.

As described above, the examiner can evaluate the surface shape of the disk based on the sectional shape, SJ value, and RO value displayed on the monitor 12. Further, since the positions of SJ _max and RO _{max with} respect to the overall shape (three-dimensional shape) are displayed, it is possible to know the relationship between the flatness and SJ, RO. Further, it can be used for production management, improvement of production process, etc. by creating a distribution chart based on the result of SJ value and RO value on the entire surface and collecting statistics.

[0036]

As described above, according to the present invention, the inspection of the flatness of the sample and the inspection of the degree of change of the shape of the edge portion of the sample can be performed by one machine in a short time. it can. Also flatness and roll-off or ski jump
You can know the relationship with.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a surface inspection device.

FIG. 2 is a flowchart of surface inspection.

FIG. 3 is an explanatory diagram of an SJ / RO detection method.

FIG. 4 is a display example of a cross-sectional shape.

FIG. 5 is a display example of SJ / RO on a contour map.

[Explanation of symbols]

4'reference plane 6 discs 6'Measured surface 11 Image processing device 12 monitors 13 Control unit 20a, 20b mark 31a and 31b marks L reference line

Claims (3)

(57) [Claims] 1. A surface inspection for inspecting a surface shape of a disk.
In the device, de changing the phase a oblique incidence interferometry
The flatness analysis is performed by the interference fringe forming means for sequentially forming the interference fringes by the light reflected on the disc surface and the reference surface and the image acquisition means for capturing the images of the interference fringes having different phases.
The flatness analyzer that displays in a fixed format and the disc
Area in the radial direction, where sudden shape changes are likely to occur
Test areas have an edge portion, the inspection area be outside the examination region
Setting means for setting a neighborhood area of a small section that is close to and is not affected by the overall deflection, etc., and a reference gland of a desired radial cross section is obtained based on the three-dimensional shape data in the neighborhood area, and inspection is performed on the reference gland. analyzing means for obtaining the amount of displacement in the cross direction of the area, and outputs an analysis result by said analysis means
Both are based on the analysis results and the 3D shape data.
And a means for outputting a correspondence relationship with the analysis result of the flatness including the edge. 2. The surface inspection apparatus according to claim 1, wherein
The inspection area is the same as the inspection area for roll-off or ski jump.
However, the correspondence between the analysis result and the flatness analysis result is
A surface inspection apparatus characterized by being obtained by displaying a mark on a flatness analysis diagram at a position showing the maximum value of roll-off or the maximum value of ski jump obtained by the analysis means. 3. The surface inspection apparatus according to claim 1, wherein
The inspection area is the same as the inspection area for roll-off or ski jump.
However, the correspondence between the analysis result and the flatness analysis result is
It is obtained by displaying the distribution of the portion satisfying the set condition from the roll-off or ski-jump data obtained by the analyzing means on the flatness analysis chart .
Surface inspection apparatus characterized by being.