CN112665536A - Method and device for measuring edge roughness of wafer - Google Patents
Method and device for measuring edge roughness of wafer Download PDFInfo
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- CN112665536A CN112665536A CN202011611869.1A CN202011611869A CN112665536A CN 112665536 A CN112665536 A CN 112665536A CN 202011611869 A CN202011611869 A CN 202011611869A CN 112665536 A CN112665536 A CN 112665536A
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Abstract
The invention provides a method and a device for measuring edge roughness of a wafer, wherein the method comprises the following steps: irradiating the light beam to the edge of the wafer to be scattered, wherein the scattered light is collected on a photoelectric sensor after being reflected by reflectors arranged on the upper side and the lower side of the wafer; the photoelectric sensor acquires scattered light signals of the edge of the wafer; and carrying out Fourier transform on the scattered light signals to obtain the edge roughness of the wafer. The measuring method is simple and quick, does not need additional operation of cutting a sample, has no destructiveness, does not influence the yield, and can test the edge roughness of the whole circumference of the wafer.
Description
Technical Field
The invention belongs to the technical field of integrated circuit manufacturing, and particularly relates to a method and a device for measuring edge roughness of a wafer.
Background
Before the wafer is not processed with circuits, it is necessary to know whether the wafer is flat or not so as to confirm the subsequent layout status. After the wafer is used for manufacturing a circuit, the roughness data needs to be monitored so as to ensure the quality of the subsequent process. Wafer surface roughness is measured, most commonly by AFM (Atomic Force Microscope) measurements, typically with 1 wafer per day per Atomic Force Microscope. During measurement, sample small blocks are cut out of the wafer, only 1 position is usually sampled, the size of the sample small blocks needs to be smaller than 2cm multiplied by 2cm, the measurement is carried out in an analysis range area of 100 mu m multiplied by 100 mu m under AFM, and only the roughness of the edge surface (upper inclined plane) of the upper half part of the wafer can be tested by a single measurement. During AFM detection, the wafer needs to be damaged for analysis, which also results in that the sampled wafer cannot be analyzed by other experiments. Conventional AFM measurements present conditions where manual operation is inefficient, destructive, affects throughput, and detection over a small area is not representative of the edge of an entire wafer.
Therefore, a suitable method for measuring the edge roughness of the wafer is needed.
Disclosure of Invention
The invention aims to provide a method for measuring the edge roughness of a wafer, which is simple and quick, has no destructiveness and can test the edge roughness of the whole circumference of the wafer.
The invention provides a method for measuring edge roughness of a wafer, which comprises the following steps:
irradiating the light beam to the edge of the wafer to be scattered, wherein the scattered light is collected on a photoelectric sensor after being reflected by reflectors arranged on the upper side and the lower side of the wafer;
the photoelectric sensor acquires scattered light signals of the edge of the wafer;
and carrying out Fourier transform on the scattered light signals to obtain the edge roughness of the wafer.
Further, the edge roughness of the wafer is characterized by power spectral density.
Further, the photosensor includes: a photodiode or a charge coupled device.
Further, the beam includes a first beam that is irradiated from a peripheral side of the wafer to an edge of the wafer.
Further, the light beam also comprises a second light beam irradiated to the edge of the wafer from the upper part of the wafer and/or a third light beam irradiated to the edge of the wafer from the lower part of the wafer.
Further, the wavelength range of the light beam is as follows: 1 nm to 100 nm.
The invention also provides a device for measuring the edge roughness of the wafer, which comprises:
the radiation source is at least arranged on the peripheral side of the wafer;
the reflecting mirrors are arranged on the upper side and the lower side of the wafer;
the photoelectric sensor is arranged on one side, away from the center of the circle, of the edge of the wafer;
the light beam emitted by the radiation source irradiates the edge of the wafer to be scattered, and the scattered light is collected on the photoelectric sensor after being reflected by the reflecting mirror.
Furthermore, the reflectors arranged on the upper side and the lower side of the wafer form a semi-ellipse or a semi-circle.
Further, the radiation source is disposed between the edge of the wafer and the photosensor.
Further, the method also comprises the following steps: and the rotating unit is used for driving the wafer to rotate.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a method and a device for measuring edge roughness of a wafer, wherein the method comprises the following steps: irradiating the light beam to the edge of the wafer to be scattered, wherein the scattered light is collected on a photoelectric sensor after being reflected by reflectors arranged on the upper side and the lower side of the wafer; the photoelectric sensor acquires scattered light signals of the edge of the wafer; and carrying out Fourier transform on the scattered light signals to obtain the edge roughness of the wafer. The measuring method is simple and quick, does not need additional operation of cutting a sample, has no destructiveness, does not influence the yield, and can test the edge roughness of the whole circumference of the wafer.
Drawings
Fig. 1 is a flowchart illustrating a method for measuring edge roughness of a wafer according to an embodiment of the invention.
Fig. 2 is a schematic view of an apparatus for measuring edge roughness of a wafer according to an embodiment of the invention.
Fig. 3a is a schematic diagram of an edge testing position of a wafer according to an embodiment of the invention.
FIG. 3b is a schematic diagram of scattered light signals of different roughness tests of the edge of the wafer according to the embodiment of the invention.
Fig. 4 is a PSD and frequency curve diagram of the edge test of the wafer according to the embodiment of the invention.
FIG. 5 is a schematic diagram of a fitting line between PSD and AFM Rq according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating PSD corresponding to different polishing levels according to an embodiment of the present invention.
Wherein the reference numbers are as follows:
b-a laser box; b1 — first light beam; b2 — second beam; b3 — third beam; 10-a wafer; a-the edge of the wafer; 20-a mirror; 30-photoelectric sensor.
Detailed Description
Based on the above research, the embodiment of the invention provides a method and a device for measuring the edge roughness of a wafer. The invention is described in further detail below with reference to the figures and specific examples. The advantages and features of the present invention will become more apparent from the following description. It is to be noted, however, that the drawings are designed in a simplified form and are not to scale, but rather are to be construed in an illustrative and descriptive sense only and not for purposes of limitation.
An embodiment of the present invention provides a method for measuring edge roughness of a wafer, as shown in fig. 1, including:
irradiating the light beam to the edge of the wafer to be scattered, wherein the scattered light is collected on a photoelectric sensor after being reflected by reflectors arranged on the upper side and the lower side of the wafer;
the photoelectric sensor acquires scattered light signals of the edge of the wafer;
and carrying out Fourier transform on the scattered light signals to obtain the edge roughness of the wafer.
As shown in fig. 2, the wafer 10 may be fixed by an electrostatic chuck on a rotation unit, and the rotation unit rotates the wafer 10 when the wafer edge a is picked up. A radiation source, for example a laser source, is arranged at the edge a of the wafer, on the side remote from the center of the wafer. The radiation source emits a first beam B1 and the mirrors 20 are arranged on both the upper and lower sides of the wafer 10, for example one mirror 20 above and below, the upper and lower mirrors 20 being symmetrical with respect to the plane of the wafer 10. The upper and lower mirrors 20 may, for example, form a semi-elliptical or semi-circular shape. The photosensors 30 are distributed on a side of the edge a of the wafer away from the center of the wafer, and the exemplary radiation source (not shown) emitting the first beam B1 is distributed between the edge a of the wafer and the photosensors 30. Further, a radiation source may be positioned above and/or below the edge A of the wafer to emit a second beam B2 and/or a third beam B3. The photosensor 30 is, for example, a photodiode or a CCD (charge coupled device). The photosensor 30 collects scattered light from the edge a of the wafer as the edge a of the wafer is scanned by the beam from the radiation source.
The wavelength range of the light beam is as follows: 1 nm to 100 nm; optionally in the range of 5 nm to 50 nm; or alternatively in the range of 10 nm to 20 nm.
As shown in fig. 2, fig. 3a and fig. 3b, an arc length CD obtained by rotating counterclockwise by 60 ° to 120 ° with a radius where a center O of the wafer 10 and a Notch (positioning hole) V of the wafer are located as a reference is taken as an example of an actually measured range of the edge of the wafer. In fig. 3b, the abscissa represents the distribution of the rotation angle of 60 ° to 120 °, the ordinate represents the collected scattered light signal at the wafer edge corresponding to the rotation angle, and the unit of the ordinate is mA. Two curves, 0.25POR and 0.5POR, POR (Production of record), xPOR representing the degree of polishing, are shown in fig. 3b, the smaller the coefficient x, the smaller the degree of polishing, the rougher the corresponding edge of the wafer; the larger the coefficient x, the greater the polishing level, and the less rough (smooth) the edge of the corresponding wafer. Illustratively, 0.25POR is 0.25 times the conventional polishing time, and 0.5POR is 0.5 times the conventional polishing time. The edge of the wafer was polished to varying degrees and an edge roughness test of the wafer was performed. In fig. 3b, the roughness of the 0.25POR curve is larger than that of the 0.5POR curve, and the scattered light signal measured by the ordinate is also larger.
The Power Spectral Density (PSD) versus frequency is shown in fig. 4. Specifically, the edge roughness of the wafer may be characterized by a Power Spectral Density (PSD). The method includes inspecting a profile of an edge surface of a wafer by a laser during edge defect inspection, calculating a Power Spectral Density (PSD) from the profile of the edge surface, and characterizing edge roughness using the PSD. Determining the edge roughness parameter includes determining a power spectral density of the edge roughness parameter based on a distribution of the scatter signals. The Power Spectral Density (PSD) describes how the power of a continuous signal is distributed over frequency. In fig. 4, the abscissa represents frequency in units of: 1/rad. The ordinate is the Power Spectral Density (PSD). The 0.25POR curve has a larger roughness than the 0.5POR curve, and the corresponding Power Spectral Density (PSD) measured on the ordinate is also larger.
The method for measuring the edge roughness of the wafer in this embodiment uses Power Spectral Density (PSD) to characterize the roughness, and the method for measuring the Atomic Force Microscope (AFM) uses AFM Rq (root mean square roughness) to characterize the roughness. The Atomic Force Microscope (AFM) is mainly based on the principle that a cantilever beam generates a fine displacement by the Atomic Force between a needle tip and a test piece to measure the surface roughness (topography fluctuation) of a sample. As shown in fig. 5, the Power Spectral Density (PSD) and AFM Rq (root mean square roughness) were fitted to obtain a fitted straight line. The experimental data shows that the Power Spectral Density (PSD) and the AFM Rq (root mean square roughness) have consistency and better correlation.
The Power Spectral Density (PSD) can capture different wafer edge roughness. Wafers with different roughness were tested. As shown in fig. 6, POR (Production of record) performs various degrees of polishing on the edge of the wafer and performs an edge roughness test on the wafer. The abscissa in the graph represents the polishing degree, xCOR, the smaller the coefficient x, the smaller the polishing degree, and the rougher the edge of the corresponding wafer; the larger the coefficient x, the greater the polishing level, and the less rough (smooth) the edge of the corresponding wafer. In fig. 6, 0.25POR, 0.5POR, 0.75POR, 1POR, and 1.5POR gradually increase the polishing degree, and correspondingly, the edge roughness of the polished wafer gradually decreases. A rough surface will have a stronger scattered light optical signal than a smooth surface; correspondingly, the greater the roughness, the greater the Power Spectral Density (PSD) value. Testing the same batch of wafers, wherein the polishing records of the wafers with the numbers 01, 03 and 05 are 0.25 POR; wafers numbered 06, 08 and 10 correspond to a polish record of 0.5 POR; wafers numbered 11, 13, and 15 correspond to a polish record of 0.75 POR; the wafers numbered 16, 18 and 20 correspond to a polish record of 1 POR; the wafers numbered 21, 23 and 25 correspond to a polish recorded as 1.5 POR. In the method for measuring the edge roughness of the wafer, the roughness is represented by Power Spectral Density (PSD), and the ordinate in the graph represents an actual measured value of the PSD, and it can be seen from the graph that the actual measured PSD is smaller and smaller as the polishing degree of the abscissa is gradually increased, that is, the edge roughness of the wafer is smaller and smaller, and experimental data well proves that the test method of the embodiment is effective.
The Power Spectral Density (PSD) decomposes the measured surface structure into components for each spatial frequency, and determines the density value of each component. The edge surface contour fluctuation of the wafer can be regarded as a complex vibration phenomenon formed by superposition of harmonics with different frequencies and different amplitudes, a Power Spectral Density (PSD) function comprises various frequency components, and a curve of the PSD function reflects the weight distribution of each spatial frequency component.
The present invention also provides a device for measuring edge roughness of a wafer, as shown in fig. 2, including:
a radiation source (not shown) disposed at least on the peripheral side of the wafer 10;
the reflecting mirrors 20 are arranged on the upper side and the lower side of the wafer 10;
the photoelectric sensor 30 is arranged on one side, away from the center of the wafer, of the edge of the wafer 10;
the light beam emitted from the radiation source irradiates the edge a of the wafer 10 to be scattered, and the scattered light is reflected by the mirror 20 and then is collected on the photoelectric sensor 30. Specifically, the reflecting mirrors 20 are disposed on the upper and lower sides of the wafer 10. Therefore, the light beam irradiated to the edge surface (upper inclined plane) of the upper half part in the thickness direction of the wafer can be reflected by the upper reflector and then is gathered on the photoelectric sensor; the light beam irradiated to the lower half edge surface (lower inclined surface) in the thickness direction of the wafer can be reflected by the lower reflector and then focused on the photoelectric sensor 30; therefore, the edge roughness of the entire surface above and below the edge of the wafer can be tested. The reflectors 20 disposed on the upper and lower sides of the wafer 10 form a semi-elliptical shape or a semi-circular shape.
The radiation source is disposed between the edge of the wafer 10 and the photosensor 30.
The measuring device further includes: the wafer 10 can be fixed on the rotating unit through the electrostatic chuck, and the rotating unit drives the wafer 10 to rotate when the edge A of the wafer is collected, so that the edge roughness of the whole circumference of the wafer can be tested.
In summary, the present invention provides a method and an apparatus for measuring edge roughness of a wafer, wherein the method comprises: irradiating the light beam to the edge of the wafer to be scattered, wherein the scattered light is collected on a photoelectric sensor after being reflected by reflectors arranged on the upper side and the lower side of the wafer; the photoelectric sensor acquires scattered light signals of the edge of the wafer; and carrying out Fourier transform on the scattered light signals to obtain the edge roughness of the wafer. The measuring method is simple and quick, does not need additional operation of cutting a sample, has no destructiveness, does not influence the yield, and can test the edge roughness of the whole circumference of the wafer.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the method disclosed by the embodiment, the description is relatively simple because the method corresponds to the device disclosed by the embodiment, and the relevant points can be referred to the description of the method part.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (10)
1. A method for measuring the edge roughness of a wafer is characterized by comprising the following steps:
irradiating the light beam to the edge of the wafer to be scattered, wherein the scattered light is collected on a photoelectric sensor after being reflected by reflectors arranged on the upper side and the lower side of the wafer;
the photoelectric sensor acquires scattered light signals of the edge of the wafer;
and carrying out Fourier transform on the scattered light signals to obtain the edge roughness of the wafer.
2. The method of claim 1, wherein the edge roughness of the wafer is characterized by a power spectral density.
3. The method of claim 1, wherein the photoelectric sensor comprises: a photodiode or a charge coupled device.
4. The method of claim 1, wherein the beam comprises a first beam that is directed from a peripheral side of the wafer to an edge of the wafer.
5. The method of claim 4, wherein the beam further comprises a second beam irradiated to the edge of the wafer from above the wafer and/or a third beam irradiated to the edge of the wafer from below the wafer.
6. The method of claim 1, wherein the wavelength range of the light beam is: 1 nm to 100 nm.
7. An apparatus for measuring edge roughness of a wafer, comprising:
the radiation source is at least arranged on the peripheral side of the wafer;
the reflecting mirrors are arranged on the upper side and the lower side of the wafer;
the photoelectric sensor is arranged on one side, away from the center of the circle, of the edge of the wafer;
the light beam emitted by the radiation source irradiates the edge of the wafer to be scattered, and the scattered light is collected on the photoelectric sensor after being reflected by the reflecting mirror.
8. The apparatus for measuring edge roughness of a wafer according to claim 7, wherein the reflectors disposed on the upper and lower sides of the wafer form a semi-elliptical or semi-circular shape.
9. The apparatus of claim 7, wherein the radiation source is disposed between the edge of the wafer and the photosensor.
10. The apparatus for measuring edge roughness of a wafer of claim 7, further comprising:
and the rotating unit is used for driving the wafer to rotate.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011611869.1A CN112665536A (en) | 2020-12-30 | 2020-12-30 | Method and device for measuring edge roughness of wafer |
| TW110111818A TWI774300B (en) | 2020-12-30 | 2021-03-31 | An apparatus and a method for measuring rimmed roughness of a wafer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011611869.1A CN112665536A (en) | 2020-12-30 | 2020-12-30 | Method and device for measuring edge roughness of wafer |
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| CN112665536A true CN112665536A (en) | 2021-04-16 |
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| CN202011611869.1A Pending CN112665536A (en) | 2020-12-30 | 2020-12-30 | Method and device for measuring edge roughness of wafer |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1809744A (en) * | 2003-05-19 | 2006-07-26 | 微-埃普西龙测量技术有限两合公司 | Method and apparatus for optically controlling the quality of objects having a circular edge |
| CN1906478A (en) * | 2003-12-10 | 2007-01-31 | 以色列商·应用材料以色列公司 | Advanced roughness metrology |
| CN101171506A (en) * | 2005-05-06 | 2008-04-30 | 恪纳腾技术公司 | Wafer edge inspection |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5592295A (en) * | 1995-05-08 | 1997-01-07 | Memc Electronic Materials, Inc. | Apparatus and method for semiconductor wafer edge inspection |
| JP2013093389A (en) * | 2011-10-24 | 2013-05-16 | Hitachi High-Technologies Corp | Optical inspection device and edge inspection device |
| US9053527B2 (en) * | 2013-01-02 | 2015-06-09 | Kla-Tencor Corp. | Detecting defects on a wafer |
| US9719943B2 (en) * | 2014-09-30 | 2017-08-01 | Kla-Tencor Corporation | Wafer edge inspection with trajectory following edge profile |
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2020
- 2020-12-30 CN CN202011611869.1A patent/CN112665536A/en active Pending
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- 2021-03-31 TW TW110111818A patent/TWI774300B/en active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1809744A (en) * | 2003-05-19 | 2006-07-26 | 微-埃普西龙测量技术有限两合公司 | Method and apparatus for optically controlling the quality of objects having a circular edge |
| CN1906478A (en) * | 2003-12-10 | 2007-01-31 | 以色列商·应用材料以色列公司 | Advanced roughness metrology |
| CN101171506A (en) * | 2005-05-06 | 2008-04-30 | 恪纳腾技术公司 | Wafer edge inspection |
Non-Patent Citations (1)
| Title |
|---|
| 沈正祥等: "利用功率谱密度函数表征光学薄膜基底表面粗糙度", 中国光学学会2006年学术大会论文摘要集中国光学学会, pages 618 - 619 * |
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| TWI774300B (en) | 2022-08-11 |
| TW202225639A (en) | 2022-07-01 |
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