CN115980083A - Wafer and chip defect detection system and method based on linear array Brillouin microscopy - Google Patents
Wafer and chip defect detection system and method based on linear array Brillouin microscopy Download PDFInfo
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Abstract
The invention discloses a wafer and chip defect detection system and method based on linear array Brillouin microscopy, and belongs to the field of optical precision measurement and the field of wafer detection. In the system, a Brillouin scattering detection module, a bright field detection module and a signal processing and feedback module are connected, and the signal processing and feedback module is connected with a displacement module; the signal processing and feedback module is connected with the imaging and analyzing module, and single wire harness measuring data is transmitted to the imaging and analyzing module; the displacement module is connected with the sample; the Brillouin scattering detection module and the bright field detection module are connected with the sample to realize the acquisition of sample information. According to the invention, the mechanical properties of the samples such as the wafer and the non-transparent chip can be subjected to line scanning confocal measurement through the Brillouin scattering detection module, so that the Brillouin scattering detection speed is greatly improved; the combination of bright field linear array detection and Brillouin scattering linear array detection can simultaneously obtain the geometric defects and mechanical stress defects of wafer and chip samples, and broaden defect detection parameters.
Description
Technical Field
The invention belongs to the field of optical precision measurement and the field of wafer detection, and mainly relates to a wafer and chip defect detection system and method based on linear array Brillouin microscopy.
Background
The defect detection of wafers and chips is a key link in chip manufacturing and processing, and with the development of chip manufacturing processes, not only is recording required to be carried out on defects such as scratches, particles and grooves on the surfaces of the chips, but also measurement is gradually required to be carried out on defects such as mechanical properties, chemical components and lattice structures of the chips.
The traditional wafer defect detection method is based on bright field illumination or dark field photoinduced excitation illumination to detect the defects on the surface or the sub-surface of the wafer, for example, the Chinese patent publications with the publication numbers of CN112505064A and CN114441440A disclose a wafer defect detection method in a partitioned area, which realizes the synchronous and rapid detection of a bright field array and a dark field array, but the detection range is limited to geometric defects.
Brillouin scattering microscopic imaging is a new microscopic method, and can detect the mechanical properties and stress distribution of wafers and chips, so that more performance and defect information of the wafers and chips can be known. For example, chinese patent publication No. CN113916891A discloses a microscope system for both bright field confocal detection and dark field confocal brillouin detection, which uses an optical fiber to generate an annular illumination beam and perform complementary aperture shielding detection, so as to effectively separate a sample surface reflection signal and a sub-surface scattering signal, thereby realizing three-dimensional detection of sample defects and mechanical properties. However, the method can only perform point scanning detection on the sample, and the imaging speed is limited. The thesis scientific reports 6. However, the method is a transmission type structure, only a transparent sample can be measured, and a turbid sample and an opaque sample cannot be detected.
However, in the prior art, no system which can realize the linear array detection of the Brillouin microscope and can be combined with the bright field linear array detection to realize the defect detection of the wafer and the non-transparent chip exists. The invention discloses a wafer and chip defect detection system and method based on linear array Brillouin microscopy, which can be used for rapidly acquiring the surface geometric defects of the wafer and chip by using bright field confocal microscopy, simultaneously detecting the mechanical properties of the surface of a sample by using Brillouin microscopy, and has the integrated detection function of the geometric defects and the mechanical stress defects; the technology utilizes the linear array confocal to realize the detection of bright field and Brillouin microscopy, improves the imaging speed and effectively fills the requirements.
Disclosure of Invention
The invention aims to solve the problem that the existing defect detection technology cannot carry out synchronous and rapid linear array detection on the geometric defects and the mechanical acoustic properties of a sample, and provides a linear array defect detection system with both bright field detection and Brillouin detection.
The invention adopts the following specific technical scheme:
in a first aspect, the invention provides a wafer and chip defect detection system based on linear array Brillouin microscopy, which comprises a Brillouin scattering detection module, a bright field detection module, a displacement module, a signal processing and feedback module and an imaging and analysis module;
the sample is arranged on the displacement module, and the signal processing and feedback module can control the movement of the sample through the displacement module; the Brillouin scattering detection module is used for detecting Brillouin spectrum information of the surface of a sample so as to obtain mechanical stress defect distribution information of the sample, and the bright field detection module is used for detecting bright field light intensity information of the surface of the sample so as to obtain geometric defect distribution information of the sample; the signal processing and feedback module is respectively connected with the Brillouin scattering detection module and the bright field detection module and is used for receiving the acquired detection signals and processing the detection signals into single beam measurement data; the imaging and analyzing module is connected with the signal processing and feedback module and is used for receiving, storing and imaging the single wire harness measurement data and simultaneously feeding back the result to the signal processing and feedback module.
Preferably, the sample is a wafer or a chip.
Preferably, the brillouin scattering detection module comprises a brillouin scattering linear array light source assembly, a third optical filter, a second polarization splitting prism, a second quarter wave plate, a dichroic mirror, an objective lens, a reflector, a light filtering assembly, a second cylindrical mirror, a virtual space imaging phase array, a third cylindrical mirror, an adjustable slit, a converging lens and a surface array camera which jointly form the optical system;
the parallel polarized light beams output by the Brillouin scattering linear array light source component can sequentially pass through a third light filter, a second polarization beam splitter prism, a second quarter wave plate, a dichroic mirror and an objective lens and then converge into linear light to irradiate on the surface of a sample, the light beams formed by reflection on the surface of the sample can sequentially pass through the objective lens, the dichroic mirror, the second quarter wave plate, the second polarization beam splitter prism, a reflector, a light filtering component and a second cylindrical mirror and then converge into linear light to irradiate on an incident surface of a virtual space imaging phase array, the virtual space imaging phase array is subjected to chromatic dispersion and then converges into the linear light to irradiate on an adjustable slit through a third cylindrical mirror, and the linear light is subjected to spatial filtering by the adjustable slit to filter stray light and then converged on a surface array camera through a converging lens.
Furthermore, the linear light spots focused to the virtual space imaging phase array incidence plane by the second cylindrical lens are parallel to the linear light spots formed after the objective lens is focused along the X direction.
Further, the filter assembly is used for filtering out reflected light and elastic background light, and includes, but is not limited to, an ultra-narrow bandwidth filter and an atomic absorption cell.
Further, the bright field detection module comprises a bright field linear array light source assembly, a first optical filter, a first polarization splitting prism, a first quarter wave plate, a dichroic mirror, an objective lens, a second optical filter, a first cylindrical mirror and a linear array camera which jointly form the optical system;
the vertical polarized light beams output by the bright field linear array light source assembly can sequentially pass through the first light filter, the first polarization beam splitter prism, the first quarter-wave plate, the dichroic mirror and the objective lens and then converge into linear light to irradiate on the surface of a sample, and the light beams formed by reflection on the surface of the sample can sequentially pass through the objective lens, the dichroic mirror, the first quarter-wave plate, the first polarization beam splitter prism, the second light filter and the first cylindrical mirror and converge on the linear array camera.
Preferably, the object detection regions of the brillouin scattering detection module and the bright field detection module are both linear, and the direction of focusing the object lines is along the X direction and keeps the lengths consistent.
Preferably, the displacement module comprises a clamp for clamping the sample and a driving device capable of enabling the sample to move along three directions of X, Y and Z axes.
Preferably, the imaging and analyzing module can store the received single beam measurement data, can perform splicing imaging on the multiple beam measurement data to obtain a morphology graph and a mechanical stress distribution graph of the sample, and can perform real-time analysis, statistics and identification on the imaging result on the quantity and the position of various defects; and after the complete sample morphology obtained through measurement is identified, feeding back information to the signal processing and feedback module, wherein the signal processing and feedback module can control the movement and stop of the displacement module according to a feedback result.
In a second aspect, the present invention provides a defect detection method using the wafer and chip defect detection system based on linear array brillouin microscopy, which specifically comprises:
s1: after the system is started, the bright field linear array light source assembly provides collimated vertical polarization line light source illumination, light beams are reflected by the first polarization splitting prism after being filtered by the first optical filter, the reflected light beams are changed into circular polarization light after passing through the first quarter-wave plate, then the circular polarization light passes through the dichroic mirror, and the light beams passing through the dichroic mirror are converged on the surface of a sample through the objective lens; the light reflected by the surface of the sample is collected again by the objective lens, and reaches the first quarter-wave plate after penetrating through the dichroic mirror, and the first quarter-wave plate changes the circular polarized light reflected by the sample into parallel polarized light, so that the parallel polarized light can penetrate through the first polarization splitting prism, and the light beam penetrating through the first polarization splitting prism is filtered by the second optical filter and then is converged into the linear array camera by the first cylindrical mirror;
meanwhile, the Brillouin scattering linear array light source assembly provides collimated parallel polarization line light source illumination, light beams are transmitted by the second polarization splitting prism after being filtered by the third optical filter, the transmitted light beams are changed into circular polarization light from polarization light through the second quarter-wave plate, then are reflected to the objective lens by the dichroic mirror, and are converged on the surface of a sample through the objective lens; light reflected by the surface of the sample is collected again by the objective lens, reflected by the dichroic mirror and reaches the second quarter-wave plate, the second quarter-wave plate converts circular polarized light reflected by the sample into vertical polarized light, the vertical polarized light can be reflected by the second polarization splitting prism, then reflected by the reflector and enters the filtering component, and after being filtered by the filtering component, the light beam is focused to the incident surface of the virtual space imaging phase array by the second cylindrical mirror; after the virtual space imaging phase array, carrying out dispersion expansion on linear light spots in the X direction in the Y direction to form a two-dimensional spectral image; the two-dimensional spectral image is converged into X-direction linear light spots again through a third cylindrical mirror and focused on the adjustable slit; the adjustable slit carries out spatial filtering on the light spot and filters stray signals after Y-direction dispersion; the light after passing through the adjustable slit is converged into the area-array camera through the converging lens;
in the process, the signal processing and feedback module receives detection signals sent back by the Brillouin scattering detection module and the bright field detection module in real time and processes the detection signals into single beam measurement data, the imaging and analysis module performs imaging processing on the single beam measurement data and feeds the single beam measurement data back to the signal processing and feedback module, and the signal processing and feedback module controls the displacement module according to a received feedback instruction, so that the displacement module drives a sample to move to the position under the objective lens and move to the optimal focusing position in the Z-axis direction; after focusing is finished, the signal processing and feedback module sends an instruction to enable the displacement module to stop moving;
s2: when the displacement module stops moving, the Brillouin scatteringThe detection module and the bright field detection module focus the beam line to a position (X) on the sample in parallel to the X direction through the objective lens kj ,y k ) Shaping and receiving the returned linear light beam; wherein j =1, 2.. And l, represents a single linear array having l micro-points; k =1,2.., m, which represents a total of m measurement sites on the sample, and m measurements are required; the bright field detection module directly collects the light intensity information I of the returned linear light beam through the linear array camera LF (x kj ,y k ) And transmits it to the signal processing and feedback module; the Brillouin scattering detection module acquires two-dimensional spectral information dispersed by a virtual space imaging phase array through an area array camera and transmits the two-dimensional spectral information to the signal processing and feedback module, and the signal processing and feedback module further processes the received two-dimensional spectral information and extracts Brillouin frequency shift v of each micro point B (x kj ,y k ) Brillouin line width gamma B (x kj ,y k ) And brillouin peak light intensity G B (x kj ,y k ) (ii) a The signal processing and feedback module sends the single linear array information obtained after processing to the imaging and analyzing module;
s3: the imaging and analyzing module stores and splices the single beam measurement data to image, and identifies defects and judges whether the sample is scanned completely or not by comparing 4 defect graphs (including 1 geometric defect graph and 3 mechanical stress defect graphs, wherein the 3 mechanical stress defect graphs are respectively obtained by processing Brillouin frequency shift, brillouin line width and Brillouin peak light intensity information) obtained by imaging;
if the sample is not scanned, feeding back a result to a signal processing and feedback module, sending an instruction to a displacement module by the signal processing and feedback module to enable the displacement module to move according to a scanning path, carrying out focusing processing according to the step S1, and sequentially executing the steps S2 and S3 after the displacement module stops moving; and if the sample is scanned, feeding back a result to the signal processing and feedback module, and sending an instruction to the displacement module by the signal processing and feedback module to stop moving so as to finish the defect detection of the sample.
Compared with the prior art, the invention has the following beneficial effects:
1) The confocal line scanning Brillouin microscopic imaging method adopts confocal line scanning Brillouin microscopic imaging, can measure hundreds of micro-points simultaneously, and has higher imaging speed than the traditional single-point scanning Brillouin microscopic imaging technology; compared with the existing line scanning Brillouin microscopic technology, the confocal line scanning structure can image the opaque sample, so that the application of the confocal line scanning structure to defect detection of wafers and chips becomes possible.
2) The invention can simultaneously realize bright field line scanning and Brillouin line scanning imaging of the wafer defects, and compared with the traditional line scanning type wafer defect detection system, the Brillouin line scanning imaging is added, so that the geometrical defects and the mechanical stress defects of the wafer and the chip can be simultaneously obtained, and the defect detection rate is improved.
Drawings
FIG. 1 is a schematic, diagrammatic view of a defect detection system of the present invention;
FIG. 2 is a schematic diagram of detection modules (including Brillouin detection modules and bright field detection modules) in a defect detection system according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a line scanning imaging method of the brillouin detection module according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a demodulation method of brillouin scattering line scanning microscopy according to an embodiment of the present invention, where 401 is a stress distribution diagram of a sample, 402 is a line beam diagram reflected by an objective lens in a brillouin scattering detection module, 403 is a two-dimensional spectral distribution diagram after dispersion by a virtual space imaging phase array in the brillouin scattering detection module, 404 is a brillouin spectral diagram of a single micro-point processed by a signal processing and feedback module, 405 is a brillouin signal diagram of a single beam processed by the signal processing and feedback module, and 406 is a brillouin elastography image obtained after imaging by an imaging and statistics module.
The reference numbers in the figures are: 101-Brillouin scattering detection module, 102-bright field detection module, 103-sample, 104-displacement module, 105-signal processing and feedback module, and 106-imaging and analyzing module; 201-bright field linear array light source assembly, 202-first optical filter, 203-first polarization beam splitter prism, 204-first quarter wave plate, 205-dichroic mirror, 206-objective lens, 207-second optical filter, 208-first cylindrical mirror, 209-linear array camera, 210-Brillouin scattering linear array light source assembly, 211-third optical filter, 212-second polarization beam splitter prism, 213-second quarter wave plate, 214-reflector, 215-optical filter assembly, 216-second cylindrical mirror, 217-virtual space imaging phase array, 218-third cylindrical mirror, 219-adjustable slit, 220-convergent lens and 221-area array camera.
Detailed Description
The invention will be further elucidated and described with reference to the drawings and the detailed description. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.
First, terms related to the present invention are explained: 1) The Brillouin scattering is scattering generated by interaction of an optical wave and an acoustic phonon in a sample, is inelastic scattering, generates Brillouin frequency shift and Brillouin peaks after being subjected to Brillouin scattering, and can acquire information of acoustic, thermodynamic and viscoelastic characteristics related to the sample by measuring information such as frequency shift, line width and peak light intensity of Brillouin peak energy. 2) Linear confocal, compared with point confocal, linear confocal is to adopt one-dimensional illumination sample of line beam to measure multiple points simultaneously, can improve imaging speed, and through confocal slit filtering off the non-focus aspect stray light in the sample imaging beam, thereby improve imaging contrast and resolution ratio. 3) A polarization beam splitter prism is an optical element for separating horizontally polarized and vertically polarized components of a light beam, and is embodied to transmit parallel polarized light and reflect vertically polarized light, and both the vertically polarized light (S light) and the parallel polarized light (P light) in the present invention are defined with reference to the incident plane of the polarization beam splitter prism.
As shown in fig. 1, the wafer and chip defect detection system based on linear array brillouin microscopy mainly includes a brillouin scattering detection module 101, a bright field detection module 102, a displacement module 104, a signal processing and feedback module 105, and an imaging and analysis module 106. The brillouin scattering detection module 101 and the bright field detection module 102 are used for detecting a sample 103, and transmitting the acquired detection signal to the signal processing and feedback module 105; the signal processing and feedback module 105 is configured to process the obtained detection signal, extract data for imaging, send the data to the imaging and analysis module 106, and send an instruction to control the movement of the displacement module 104; the displacement module 104 can drive the sample 103 to move along a specific track according to the signal received from the signal processing and feedback module 105; the imaging and analyzing module 106 is used for storing and imaging displaying the obtained linear array information, synchronously analyzing the imaging result, identifying various defects and recording information such as types, quantity, positions and the like, when the measured complete sample morphology is identified, feeding back the information to the signal processing and feedback module 105, and the signal processing and feedback module 105 controls the movement and stop of the displacement module 104 according to the result fed back from the imaging and analyzing module 106.
Specifically, the sample 103 is disposed on the displacement module 104, and the signal processing and feedback module 105 can control the movement of the sample 103 through the displacement module 104. The brillouin scattering detection module 101 is used for detecting brillouin spectral information of the surface of the sample 103 so as to obtain mechanical stress defect distribution information of the sample, and the bright field detection module 102 is used for detecting bright field light intensity information of the surface of the sample 103 so as to obtain geometric defect distribution information of the sample. The Brillouin scattering detection module and the bright field detection module are both connected with the signal processing and feedback module 105, and can transmit the acquired detection signals to the signal processing and feedback module 105 for preliminary processing to obtain single beam measurement data. The signal processing and feedback module 105 and the imaging and analysis module 106 are connected to transmit the single beam measurement data to the imaging and analysis module 106. The imaging and analysis module 106 can receive, store and image the single beam measurement data, and can feed the result back to the signal processing and feedback module 105.
As shown in fig. 2 and 3, the brillouin scattering detection module 101 mainly includes a brillouin scattering linear array light source assembly 210, a third optical filter 211, a second polarization splitting prism 212, a second quarter wave plate 213, a dichroic mirror 205, an objective lens 206, a reflecting mirror 214, an optical filtering assembly 215, a second cylindrical mirror 216, a virtual space imaging phase array 217, a third cylindrical mirror 218, an adjustable slit 219, a converging lens 220, and a surface array camera 221, which together form an optical system.
Specifically, parallel polarized light beams output by the brillouin scattering linear array light source assembly 210 can sequentially pass through the third optical filter 211, the second polarization splitting prism 212, the second quarter wave plate 213, the dichroic mirror 205 and the objective lens 206 and then converge into linear light to irradiate on the surface of the sample 103 (wafer or chip), light beams formed by reflection on the surface of the sample 103 can sequentially pass through the objective lens 206, the dichroic mirror 205, the second quarter wave plate 213, the second polarization splitting prism 212, the reflecting mirror 214, the optical filtering assembly 215 and the second cylindrical mirror 216 and then converge into linear light to enter an incident surface of the virtual space imaging phase array 217, the linear light is converged into the adjustable slit 219 through the third cylindrical mirror 218 after the virtual space imaging phase array is dispersed, and the linear light is converged onto the surface array camera 221 through the converging lens 220 after the stray light is spatially filtered by the adjustable slit 219.
In an actual detection process, the bright field line array light source assembly 201 provides collimated vertical polarization line light source illumination, light beams are reflected by the first polarization splitting prism 203 after being filtered by the first optical filter 202, and the reflected light beams are changed into circularly polarized light after passing through the first quarter wave plate 204 and then pass through the dichroic mirror 205. The dichroic mirror 205 is designed to transmit the optical wavelength of bright field illumination and to reflect the optical wavelength of brillouin illumination. The light beam transmitted through the dichroic mirror 205 is condensed on the surface of the sample 103 by the objective lens 206. The light reflected by the surface of the sample 103 is collected again by the objective lens 206, passes through the dichroic mirror 205 and reaches the first quarter wave plate 204, and the first quarter wave plate 204 converts the circularly polarized light reflected by the sample 103 into P light, so that the P light can pass through the first polarization splitting prism 203. The use of the first polarization splitting prism 203 enables the light to be totally reflected and totally transmitted, and improves the utilization rate of the light. The light beam transmitted through the first polarization splitting prism 203 is filtered by the second filter 207 and then condensed into the line camera 209 by the first cylindrical mirror 208. The first cylindrical mirror 208 converges the light beam into a linear light spot, and the linear light spot is parallel to the linear light spot focused by the objective lens 206. This completes the measurement of a single line area by a bright field detection module.
In a preferred embodiment, the optical filtering assembly can filter out the reflected light and the elastic background light, including but not limited to an ultra-narrow bandwidth filter, an atomic absorption cell, etc., and also can eliminate the elastic background light by adding a path of reference light with adjustable optical path length difference to perform michelson destructive interference with the measured light, thereby improving the contrast of the brillouin peak. The second cylindrical lens focuses the reflected light beam into linear light in the X direction and the linear light is incident into a virtual space imaging phase array (parallel to the X direction and having a certain inclination angle with the Y direction), the virtual space imaging phase array disperses the linear light to enable the linear light to generate large-angle dispersion in the Y direction to obtain a two-dimensional spectral image, and the two-dimensional spectral image is measured by an area array camera to obtain the Brillouin spectrum of each X-direction micro point of the linear light. The linear light spots which are focused to the incident surface of the virtual space imaging phase array 217 through the line of the second cylindrical lens 216 are parallel to the linear light spots formed after the focusing of the objective lens 206 along the X direction.
As shown in fig. 2, the bright field detection module 102 mainly includes a bright field line source assembly 201, a first optical filter 202, a first polarization splitting prism 203, a first quarter-wave plate 204, a dichroic mirror 205, an objective lens 206, a second optical filter 207, a first cylindrical mirror 208, and a line camera 209, which together form an optical system.
Specifically, the vertically polarized light beams output by the bright field linear array light source assembly 201 can sequentially pass through the first optical filter 202, the first polarization splitting prism 203, the first quarter wave plate 204, the dichroic mirror 205 and the objective lens 206 and then converge into linear light to irradiate on the surface of the sample 103, and the light beams formed by the reflection on the surface of the sample 103 can sequentially pass through the objective lens 206, the dichroic mirror 205, the first quarter wave plate 204, the first polarization splitting prism 203, the second optical filter 207 and the first cylindrical mirror 208 and converge on the linear array camera 209.
As shown in fig. 3, in the actual detection process, the brillouin scattering linear array light source assembly 210 provides collimated parallel polarization light source (P light in fig. 3) for illumination, the light beam is filtered by the third optical filter 211 and transmitted by the second polarization splitting prism 212, the transmitted light beam is changed from polarized light into circularly polarized light by the second quarter wave plate 213, and then reflected by the dichroic mirror 205 to the objective lens 206, and is converged on the surface of the sample 103 by the objective lens 206. The light reflected by the surface of the sample 103 is collected again by the objective lens 206, reflected by the dichroic mirror 205 and reaches the second quarter wave plate 213, and the second quarter wave plate 213 changes the circularly polarized light reflected by the sample 103 into vertically polarized light (S light in fig. 3), so that the vertically polarized light can be reflected by the second polarization splitting prism 212, and then reflected by the mirror 214 and incident into the optical filtering assembly 215. The filtering component 215 has a filtering function with an ultra-narrow line width, and can suppress elastic scattered light caused by reflection of the confocal structure, thereby improving the extinction ratio of the brillouin signal. After being filtered by the filter assembly 215, the light beam is line-focused by the second cylindrical mirror 216 to the incident surface of the virtual space imaging phase array 217. The line-focused linear spot is parallel to the line-focused linear spot of the objective lens 206 (both along the X-direction, as shown in fig. 3). After passing through the virtual space imaging phase array 217, the X-direction linear light spots are dispersed and spread in the Y-direction to form a two-dimensional spectral image, as shown in fig. 3. The two-dimensional spectrum image is converged into an X-direction linear spot again by the third cylindrical mirror 218 and focused on the adjustable slit 219. The adjustable slit 219 performs spatial filtering on the light spot to filter out stray signals after Y-direction dispersion. The light passing through the adjustable slit 219 is converged into the area-array camera 221 by the converging lens 220. This completes the measurement of a single line region by one brillouin scattering detection module.
In a preferred embodiment, the brillouin scattering linear array light source assembly and the bright field linear array light source assembly can obtain linear light spots with consistent directions (both along the X direction) at the sample to be measured through shaping and processing of optical systems in the respective modules, and the light sources need to be uniform enough. That is, the object detection regions of the brillouin detection module 101 and the bright field detection module 102 are both linear, and are both in the X direction and have uniform lengths in the direction of object line focusing. The light source wavelengths of the bright field detection module and the Brillouin scattering detection module are different, and the light source wavelengths are introduced into respective detectors through dichroic mirrors to be received. The linear array camera can measure the reflected bright field light beam and obtain the bright field light intensity of each X-direction micro point of the linear light.
In a preferred embodiment, the signal processing and feedback module can process the results detected by the area-array camera and the line-array camera, and by processing the results returned by the area-array camera, brillouin information of each X-direction micro-point can be obtained, wherein the brillouin information comprises brillouin frequency shift, brillouin peak line width and brillouin peak intensity; by processing the results returned by the line camera, bright field light intensity information of each X-direction micro-point can be obtained. The signal processing and feedback module transmits the single-time wiring harness measurement data obtained by processing to the imaging and analyzing module, and sends an instruction to the displacement module to control the movement of the displacement module.
In a preferred embodiment, the displacement module 104 mainly includes a clamp for clamping the sample 103 and a driving device capable of moving the sample 103 along three directions of X, Y and Z axes, so as to control the position of the sample according to the control command of the signal processing and feedback module, thereby realizing line scanning imaging of the sample.
In a preferred embodiment, the imaging and analysis module 106 is capable of storing the received single beam measurements, performing a mosaic imaging of the multiple beam measurements to obtain a geometric map and a mechanical stress profile of the sample 103, and analyzing, counting and identifying the number and location of various defects (scratches, particles, grooves, stress non-uniformities, etc.) in real time from the imaging results. When the shape of the complete sample 103 is identified, the information is fed back to the signal processing and feedback module 105, and the signal processing and feedback module 105 can control the movement and stop of the displacement module 104 according to the feedback result.
The method for detecting the defects of the sample by using the defect detection system comprises the following steps:
s1: and focusing. The method comprises the following steps:
after the system is started, the Brillouin scattering detection module, the bright field detection module and the signal processing and feedback module all start to work. The signal processing and feedback module 105 receives detection signals sent back by the brillouin scattering detection module 101 and the bright field detection module 102 in real time and processes the detection signals into single beam measurement data, the imaging and analysis module 106 performs imaging processing on the single beam measurement data and feeds the imaging processing data back to the signal processing and feedback module 105, and the signal processing and feedback module 105 controls the displacement module 104 according to a received feedback instruction, so that the displacement module 104 drives the sample 103 to move to the position under the objective lens 206 and move to the optimal focusing position in the Z-axis direction. The optimal focusing position here is a position enabling the line camera and the area camera to image clearly. After focusing is completed, the signal processing and feedback module 105 sends an instruction to stop the movement of the displacement module 104.
S2: and acquiring single linear array information. The method comprises the following steps:
when the displacement module 104 stops moving, the brillouin scattering detection module 101 and the bright field detection module 102 focus the light beam to a position (X) on the sample 103 parallel to the X direction by the same confocal objective lens 206 kj ,y k ) And shapes and receives the returned line-shaped light beam. Wherein j =1, 2.. And l, represents a single linear array having l micro-points; k =1,2.., m, which represents a total of m measurement sites on the sample, and m measurements are required; . The bright field detection module 102 directly collects the light intensity information I of the returned linear light beam through the line camera 209 LF (x kj ,y k ) And transmits it to the signal processing and feedback module 105. The Brillouin scattering detection module 101 acquires the two-dimensional spectrum information dispersed by the virtual space imaging phase array 217 through the area-array camera 221 and transmits the two-dimensional spectrum information to the signal processing and feedback module 105, and the signal processing and feedback module 105 further processes the received two-dimensional spectrum information and extracts Brillouin frequency shift v of each micro point B (x kj ,y k ) Brillouin line width gamma B (x kj ,y k ) And brillouin peak light intensity G B (x kj ,y k ). The signal processing and feedback module 105 sends the processed single linear array information to the imaging and analysis module 106.
S3: line scanning, imaging and statistical analysis. The method comprises the following steps:
the imaging and analyzing module 106 stores and splices the single-time beam measurement data, synchronously performs statistics, recording and displaying on the number, type and position of defects of the currently completed imaging result, and judges whether the sample scanning is completed. If the sample 103 is not scanned, the result is fed back to the signal processing and feedback module 105, the signal processing and feedback module 105 sends an instruction to the displacement module 104 to move the displacement module according to the scanning path, the focusing process is performed according to the step S1, and the steps S2 and S3 are sequentially performed after the displacement module 104 stops moving. If the sample 103 is scanned, the result is fed back to the signal processing and feedback module 105, and the signal processing and feedback module 105 sends an instruction to the displacement module 104 to stop moving, so as to complete the defect detection of the sample 103.
As shown in fig. 4, a demodulation imaging process of brillouin scattering line scanning microscopy in an embodiment of the present invention is shown, which is as follows:
the wafer or chip has a specific stress distribution, as shown by 401 in fig. 4, the brillouin scattering beam is converged into an X-direction line spot by the objective lens 206 and focused on the sample 103, the incident light reacts with the acoustic phonon in the sample to generate brillouin scattering, the backward brillouin scattering is captured by the objective lens 206 and returns in situ, and a line-shaped beam carrying brillouin scattering information is obtained, as shown by 402 in fig. 4. The longitudinal modulus M (v) of a single micro-point in the sample is related to the brillouin scattering information and can be expressed as:
M(ν)＝M’(ν)+iM”(ν)
wherein ν is frequency, M 'is storage modulus, M' is loss modulus, and i is imaginary unit. The storage modulus represents the rigidity and elasticity characteristic information of the material and Brillouin frequency shift v B In relation to the confocal optical path, the Brillouin scattering angle is 180 degrees, so the storage modulus M' of a single point in the sample and the Brillouin frequency shift v B The relationship of (1) is:
in the formula of lambda 0 The wavelength of incident light of the Brillouin scattering detection module is shown, n is the refractive index of the sample, and rho is the mass density of the sample. The storage modulus of a single point can be calculated by measuring the brillouin frequency shift of the point.
The longitudinal viscosity characteristic of the loss modulus characterization material is related to both Brillouin frequency shift and line width, and for a confocal light path, the loss modulus M' of a single point in a sample and the Brillouin frequency shift v B And line width Γ B Is onThe method comprises the following steps:
the loss modulus at that point can therefore be calculated by measuring the brillouin frequency shift and brillouin linewidth.
Further, the intensity G of the Brillouin spectral peak B The relevant information of the sample can also be characterized. Therefore, different mechanical property information of the sample can be obtained by extracting Brillouin frequency shift, brillouin line width and Brillouin peak gain of the Brillouin spectrum, and finally, a mechanical stress graph of the sample is drawn through the imaging and analyzing module, wherein the mechanical stress graph comprises a Brillouin frequency shift graph (namely an energy storage modulus graph), a Brillouin line width graph (namely a loss modulus graph) and a Brillouin peak light intensity graph.
However, because the brillouin frequency shift is only in the order of GHz and cannot be resolved by a camera, the dispersion separation needs to be performed by using a virtual space imaging phase array. Linear light along the X direction is incident into a virtual space imaging phase array (parallel to the X direction and having a certain inclination with the Y direction), and the virtual space imaging phase array disperses the linear light to generate large-angle dispersion in the Y direction, so as to obtain a two-dimensional spectral image, as shown by 403 in fig. 4. The two-dimensional spectral image is measured by the area-array camera, and then the measured data is transmitted to the signal processing and feedback module 105 for processing, so as to obtain the brillouin spectrum of each X-direction micro point of the linear light, as shown by 404 in fig. 4. The signal processing and feedback module 105 extracts the brillouin frequency shift value v of each micro point B Brillouin linewidth value gamma B Brillouin peak light intensity G B And transmitted to the imaging and analysis module 106 to plot the relationship between the three parameters and the individual X-ray beams, as shown at 405 in fig. 4. Through line scanning, the imaging and analyzing module 106 performs mosaic imaging on the multiple times of beam measurement data to obtain a mechanical stress distribution diagram of the sample, as shown by 406 in fig. 4 (only 1 diagram is drawn in 406 in fig. 4 for simple representation, and 3 diagrams including a brillouin frequency shift diagram, a brillouin line width diagram and a brillouin light intensity diagram can be drawn actually), and performs real-time analysis on an imaging result to count the elastic modulus-related defectThe number and location of the traps.
Therefore, the Brillouin scattering detection module can perform line scanning confocal measurement on the mechanical properties of samples such as wafers, opaque chips and the like, and the Brillouin scattering detection speed is greatly improved; the combination of bright field linear array detection and Brillouin scattering linear array detection can simultaneously obtain the geometric defects and mechanical stress defects of wafer and chip samples, and broaden defect detection parameters.
The above-described embodiments are merely preferred embodiments of the present invention, and are not intended to limit the present invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, the technical scheme obtained by adopting the mode of equivalent replacement or equivalent transformation is within the protection scope of the invention.
Claims (10)
1. A wafer and chip defect detection system based on linear array Brillouin microscopy is characterized by comprising a Brillouin scattering detection module (101), a bright field detection module (102), a displacement module (104), a signal processing and feedback module (105) and an imaging and analysis module (106);
the sample (103) is arranged on a displacement module (104), and the signal processing and feedback module (105) can control the movement of the sample (103) through the displacement module (104); the Brillouin scattering detection module (101) detects Brillouin spectral information of the surface of the sample (103) to obtain mechanical stress defect distribution information of the sample, and the bright field detection module (102) detects bright field light intensity information of the surface of the sample (103) to obtain geometric defect distribution information of the sample; the signal processing and feedback module (105) is respectively connected with the Brillouin scattering detection module (101) and the bright field detection module (102) and is used for receiving the acquired detection signals and processing the detection signals into single beam measurement data; the imaging and analyzing module (106) and the signal processing and feedback module (105) are connected and used for receiving, storing and imaging processing the single-time beam measurement data, and simultaneously, the result can be fed back to the signal processing and feedback module (105).
2. The linear brillouin microscopy based wafer and chip defect detection system according to claim 1, wherein the sample (103) is a wafer or chip.
3. The wafer and chip defect detection system based on linear brillouin microscopy as claimed in claim 1, wherein the brillouin scattering detection module (101) comprises a brillouin scattering linear array light source assembly (210), a third optical filter (211), a second polarization splitting prism (212), a second quarter wave plate (213), a dichroic mirror (205), an objective lens (206), a mirror (214), a filtering assembly (215), a second cylindrical mirror (216), a virtual space imaging phase array (217), a third cylindrical mirror (218), an adjustable slit (219), a converging lens (220) and a surface array camera (221) which together form an optical system;
parallel polarized light beams output by the Brillouin scattering linear array light source assembly (210) can sequentially pass through a third light filter (211), a second polarization splitting prism (212), a second quarter wave plate (213), a dichroic mirror (205) and an objective lens (206) and then converge into linear light to irradiate on the surface of a sample (103), light beams formed by reflection on the surface of the sample (103) can sequentially pass through the objective lens (206), the dichroic mirror (205), the second quarter wave plate (213), the second polarization splitting prism (212), a reflector (214), a light filtering assembly (215) and a second cylindrical lens (216) and then converge into linear light to irradiate on an incident surface of a virtual space imaging phase array (217), the linear light is dispersed by the virtual space imaging phase array (217), converged into linear light by a third cylindrical lens (218) to irradiate on an adjustable slit (219), and converged onto a plane array camera (221) by a converging lens (220) after stray light is spatially filtered by the adjustable slit (219).
4. The wafer and chip defect detection system based on linear array Brillouin microscopy as claimed in claim 3, wherein the linear light spots line-focused to the incidence plane of the virtual empty imaging phase array (217) through the second cylindrical mirror (216) are parallel to the linear light spots formed after being focused by the objective lens (206) along the X direction.
5. The linear Brillouin microscopy based wafer and chip defect detection system as claimed in claim 3, wherein the optical filtering assembly (215) is used to filter out reflected light and elastic background light, including but not limited to ultra-narrow bandwidth filters and atomic absorption cells.
6. The wafer and chip defect detection system based on line Brillouin microscopy according to claim 3, wherein the bright field detection module (102) comprises a bright field line light source assembly (201), a first optical filter (202), a first polarization splitting prism (203), a first quarter wave plate (204), a dichroic mirror (205), an objective lens (206), a second optical filter (207), a first cylindrical mirror (208) and a line camera (209) which together form an optical system;
the vertical polarized light beams output by the bright field linear array light source assembly (201) can sequentially pass through the first light filter (202), the first polarization splitting prism (203), the first quarter wave plate (204), the dichroic mirror (205) and the objective lens (206) and then are converged into linear light to irradiate on the surface of the sample (103), and the light beams formed by reflection on the surface of the sample (103) can sequentially pass through the objective lens (206), the dichroic mirror (205), the first quarter wave plate (204), the first polarization splitting prism (203), the second light filter (207) and the first cylindrical lens (208) and are converged on the linear array camera (209).
7. The linear brillouin microscopy based wafer and chip defect detection system according to claim 1, wherein the object detection regions of the brillouin detection module (101) and the bright field detection module (102) are both linear, and are both in the X direction and keep consistent in length in the direction of object line focusing.
8. The linear brillouin microscopy based wafer and chip defect detection system according to claim 1, wherein the displacement module (104) comprises a clamp for clamping the sample (103) and a driving device capable of moving the sample (103) along three directions of X, Y and Z axes.
9. The wafer and chip defect detection system based on linear array Brillouin microscopy as defined in claim 1, wherein the imaging and analyzing module (106) is capable of storing received single beam measurement data, performing mosaic imaging on multiple beam measurement data to obtain a topography map and a mechanical stress distribution map of the sample (103), and performing real-time analysis, statistics and identification of the number and positions of various defects on the imaging result; when the shape of the complete sample (103) measured is identified, the information is fed back to the signal processing and feedback module (105), and the signal processing and feedback module (105) can control the movement and stop of the displacement module (104) according to the feedback result.
10. The defect detection method of the wafer and chip defect detection system based on the linear array Brillouin microscope as claimed in claim 6, is characterized by comprising the following steps:
s1: after the system is started, the bright field linear array light source assembly (201) provides collimated vertical polarization line light source illumination, light beams are filtered by the first optical filter (202) and then reflected by the first polarization splitting prism (203), the reflected light beams are changed into circular polarization light after passing through the first quarter-wave plate (204), then the circular polarization light passes through the dichroic mirror (205), and the light beams passing through the dichroic mirror (205) are converged on the surface of a sample (103) through the objective lens (206); the light reflected by the surface of the sample (103) is collected again by the objective lens (206), and reaches the first quarter-wave plate (204) after passing through the dichroic mirror (205), the first quarter-wave plate (204) changes the circular polarization light reflected by the sample (103) into parallel polarization light, so that the parallel polarization light can pass through the first polarization beam splitter prism (203), the light beam passing through the first polarization beam splitter prism (203) is filtered by the second optical filter (207), and then is converged into the linear array camera (209) by the first cylindrical mirror (208);
meanwhile, the Brillouin scattering linear array light source assembly (210) provides collimated parallel polarization line light source illumination, light beams are transmitted by the second polarization splitting prism (212) after being filtered by the third optical filter (211), the transmitted light beams are changed from polarized light into circularly polarized light through the second quarter-wave plate (213), then are reflected to the objective lens (206) through the dichroic mirror (205), and are converged on the surface of the sample (103) through the objective lens (206); light reflected by the surface of the sample (103) is collected again by the objective lens (206), and reaches the second quarter wave plate (213) after being reflected by the dichroic mirror (205), the second quarter wave plate (213) changes circular polarization light reflected by the sample (103) into vertical polarization light, so that the vertical polarization light can be reflected by the second polarization beam splitter prism (212), and then is incident into the light filtering component (215) after being reflected by the reflecting mirror (214), and after being filtered by the light filtering component (215), light beams are linearly focused to an incident plane of the virtual space imaging phase array (217) by the second cylindrical mirror (216); after passing through a virtual space imaging phase array (217), linear light spots in the X direction are dispersed and expanded in the Y direction to form a two-dimensional spectral image; the two-dimensional spectrum image is converged into an X-direction linear light spot again through a third cylindrical mirror (218) and focused on an adjustable slit (219); the adjustable slit (219) performs spatial filtering on the light spot to filter stray signals after Y-direction dispersion; the light rays passing through the adjustable slit (219) are converged into the area-array camera (221) through the converging lens (220);
in the process, a signal processing and feedback module (105) receives detection signals sent back by a Brillouin scattering detection module (101) and a bright field detection module (102) in real time and processes the detection signals into single beam measurement data, an imaging and analysis module (106) performs imaging processing on the single beam measurement data and feeds the single beam measurement data back to the signal processing and feedback module (105), and the signal processing and feedback module (105) controls a displacement module (104) according to a received feedback instruction, so that the displacement module (104) drives a sample (103) to move to a position right below an objective lens (206) and move to an optimal focusing position in the Z-axis direction; after focusing is finished, the signal processing and feedback module (105) sends an instruction to enable the displacement module (104) to stop moving;
s2: when the displacement module (104) stops moving, the Brillouin scattering detection module (101) and the bright field detection module (102) focus the light beam line to a position (X) on the sample (103) parallel to the X direction through the objective lens (206) kj ,y k ) Shaping and receiving the returned linear light beam; wherein j =1, 2., l, represents a single linear array having l microdots; k =1,2.. M, representing a total of m measurement sites on the sample, m measurements are required; the bright field detection module (102) directly collects the light intensity information I of the returned linear light beam through the line camera (209) LF (x kj ,y k ) And transmits it to the signal processing and feedback module (105); the Brillouin powderThe shooting detection module (101) collects two-dimensional spectrum information dispersed by the virtual space imaging phase array (217) through the area array camera (221) and transmits the two-dimensional spectrum information to the signal processing and feedback module (105), the signal processing and feedback module (105) further processes the received two-dimensional spectrum information and extracts Brillouin frequency shift v of each micro point B (x kj ,y k ) Brillouin line width gamma B (x kj ,y k ) And brillouin peak light intensity G B (x kj ,y k ) (ii) a The signal processing and feedback module (105) sends the single linear array information obtained after processing to the imaging and analysis module (106);
s3: the imaging and analyzing module (106) stores and splices the single-time beam measurement data for imaging, identifies defects by comparing defect maps obtained by imaging and judges whether the sample (103) is scanned completely; the defect map comprises a geometric defect map and a mechanical stress defect map which is obtained by processing Brillouin frequency shift, brillouin line width and Brillouin peak light intensity information respectively; if the sample (103) is not scanned completely, feeding back a result to the signal processing and feedback module (105), sending an instruction to the displacement module (104) by the signal processing and feedback module (105) to enable the displacement module to move according to the scanning path, carrying out focusing processing according to the step S1, and sequentially executing the steps S2 and S3 after the displacement module (104) stops moving; and if the sample (103) is scanned, feeding back the result to the signal processing and feedback module (105), and sending an instruction to the displacement module (104) by the signal processing and feedback module (105) to stop moving so as to finish the defect detection of the sample (103).
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| CN117890380A (en) * | 2024-03-14 | 2024-04-16 | 蓝芯存储技术(赣州)有限公司 | Chip appearance defect detection method and detection device |
| CN118129622A (en) * | 2024-05-10 | 2024-06-04 | 上海优睿谱半导体设备有限公司 | Wafer film material thickness measuring equipment and method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117890380A (en) * | 2024-03-14 | 2024-04-16 | 蓝芯存储技术(赣州)有限公司 | Chip appearance defect detection method and detection device |
| CN117890380B (en) * | 2024-03-14 | 2024-05-14 | 蓝芯存储技术(赣州)有限公司 | Chip appearance defect detection method and detection device |
| CN118129622A (en) * | 2024-05-10 | 2024-06-04 | 上海优睿谱半导体设备有限公司 | Wafer film material thickness measuring equipment and method |
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