TWI647431B - Optical metrology apparatus and method - Google Patents

Abstract

An optical metrology device is capable of detecting any combination of specular and scattered light from photoluminescent light, broadband light across a line of the same width. The metering device includes a first source of light that produces a first illumination line on the sample. A scanning system can be used to scan an illumination spot across the sample to form the illumination line. A detector collects the photoluminescent light emitted along the illumination line. Additionally, a second illumination line can be generated on the sample using a broadband illumination source, wherein the detector collects the broadband illumination reflected along the second illumination line. A signal collecting optics collects the photoluminescent light and the broadband light and focuses it to receive a line by a light pipe. The output of the light pipe has a shape that matches one of the entrances of the detector.

Description

Optical metering device and method

Photoluminescence imaging and spectroscopy are one of the non-contact, non-destructive methods of detecting electronic structures of materials such as germanium semiconductor wafers, solar cells, and other workpieces and materials. In a typical photoluminescence process, light is directed onto a wafer or other workpiece (collectively referred to hereinafter as a "sample"), at least some of which is absorbed. The absorbed light is applied to the material via a "light excitation" procedure. The sample dissipates excess energy through a series of paths; one of which is the emission of light or photoluminescence. The intensity and spectral content of the photoluminescence are directly related to the various material properties of the sample and can therefore be used to determine the particular properties of the sample, including defects, as discussed in U.S. Patent No. 7,113,276, the disclosure of which is incorporated herein by reference. The manner is incorporated herein.

Reflective or reflective imaging is a contactless non-destructive method that uses a broadband illumination source to detect the surface and analyze the intensity and spectral content of the signal from surface rejuvenation. Surfaces can generally be classified as specular or diffuse surfaces and the physical material typically exhibits a mixture of two properties.

It is sometimes desirable to, for example, use semiconductor wafer inspection applications to measure the intensity of photoluminescence and the reflection of the spectral content and the semiconductor wafer size of the workpiece for loading in a single wafer at the same time or in a short sequence. At the same time, the quality inspection achieves the purpose of combining high-measurement space and spectral resolution to measure the amount of conveyance.

It is conventional to measure spectral photoluminescence or combined spectral photoluminescence and reflection using a single point-by-point assay scheme. In a point-by-point approach, the sample is placed on an X-Y motion (or R-Θ) system and illuminated and measured at a single excitation point. The sample is moved to another measurement point and is again illuminated and measured. By repeating the translation of the sample in the X-Y direction, a photoluminescence and reflection map can be constructed from a point-by-point measurement. However, this approach is inherently slow due to the low throughput and is therefore impractical in a full wafer inspection system, especially in the case of large sample sizes (diameters approaching and greater than 100 mm).

An optical metrology device is capable of detecting any combination of specular reflection and scattered light from a line of light across a width of the same width, broadband light. The metering device includes a first source of light that produces a first illumination line on the sample. A scanning system can be used to scan an illumination spot across the sample to form the illumination line. A detector collects the photoluminescent light emitted along the illumination line. Additionally, a second illumination line can be generated on the sample using a broadband illumination source, wherein the detector collects the broadband illumination reflected along the second illumination line. The detector can also image scattered light from the first illumination line. The illumination lines can be scanned across the sample such that all locations on the sample can be measured. A signal collecting optics collects the photoluminescent light and the broadband light and focuses it to receive a line by a light pipe. The output of the light pipe has a shape that matches one of the entrances of the detector.

In one embodiment, a device includes: an illumination source that generates a first beam; a first lens system that causes the first beam to be incident on a surface of the same body as oriented along a first direction a first illumination line incident on the sample at a first angle of incidence, wherein the sample emits photoluminescence along the first illumination line in response to excitation by the first beam Light; a second illumination source; a second lens system that will be emitted by the second illumination source Light is focused onto the sample as a second illumination line on the first illumination line oriented along the first direction and superimposed on the surface of the sample, and the second illumination line is different from the first illumination angle a second incident angle incident on the sample; a stage for providing relative movement between the sample and the first and second illumination lines in a second direction different from the first direction; a detector that collects reflected light from the second illumination line and receives photoluminescent light emitted by the sample along the first illumination line; a signal collection optic extending to the first illumination line and the first a length of one of the two illumination lines, the signal collecting optics receiving the photoluminescence light from the first illumination line and the reflected light from the second illumination line, and focusing the photoluminescence light and the reflected light into a line a light pipe having a linear receiving end for receiving the photoluminescent light focused by the signal collecting optics and the reflected light, the light pipe further having a configuration to illuminate the photoluminescent light and the reflected light Provided to the detector An output having a shape different from one of the linear receiving ends; and a processor coupled to the detector and configured to use the photoluminescent light and the reflected light for the surface of the sample A plurality of positions above determine a characteristic of the sample.

In one embodiment, a device includes: a light source that produces an illumination beam; an optical system that receives the illumination beam and produces an illumination spot on a surface of one of the samples; and a scanning system that causes the illumination A point scan spans the sample to form an illumination line, wherein the sample emits photoluminescent light along the illumination line in response to excitation by the illumination point; a stage for providing the illumination line and the sample Relative movement between the signals; a signal collecting optic extending to a length of the illumination line, the signal collecting optics receiving the photoluminescent light from the illumination line and focusing the photoluminescent light into a line; a light pipe having a linear receiving end for receiving the photoluminescent light focused by the signal collecting optics, the light pipe further having an output having a shape different from one of the linear receiving ends; a detector that collects the photoluminescent light from the light pipe, the detector having a shape with the output of the light pipe Matching one of the entrance apertures; and a processor coupled to the detector to receive the photoluminescent light to determine a characteristic of the sample.

In one embodiment, a method includes: illuminating a surface with a light source along an illumination line having one of the directions along a first direction, wherein the sample is responsive to excitation by light from the source And emitting photoluminescence light from the illumination line; collecting the photoluminescence light from the illumination line using a signal collection optic along a length of the illumination line and using the signal collection optics to focus the photoluminescence light a line; receiving the photoluminescent light along the line using a light pipe having a linear receiving end and outputting the photoluminescent light from the light pipe at an output having a shape different from one of the linear receiving ends; Detecting the photoluminescence light received from the output end of the light pipe using a detector having one of the inlet apertures shaped to match one of the output ends of the light pipe; along one of the first directions a second direction causing the illumination line to move across the surface of the sample; and determining, by using the photoluminescence light detected by the detector, a plurality of locations on the surface of the sample .

100‧‧‧Optical metering device / metering device

100'‧‧‧Optical metering device

100"‧‧‧Optical metering device

101‧‧‧ sample

104‧‧‧stage/linear stage

110‧‧‧First light source/narrowband illumination source/light source/narrowband source

111‧‧‧Select F-θ lens

112‧‧‧Optics/Lens

114‧‧‧Illumination beam/collimated illumination beam/narrowband illumination beam/scanning illumination beam/incident illumination beam

114'‧‧‧Illuminated beam/narrowband illumination beam/narrowband illumination

114"‧‧‧Narrowband illumination beam/narrowband illumination

115‧‧‧scattered light

116‧‧‧ scanning system

117‧‧‧Photoluminescent light

118‧‧‧Scan mirror/mirror

119‧‧‧beam polarizer

120‧‧‧Fixed/redirect mirror

121‧‧‧ line

122‧‧‧irradiation/excitation line

123‧‧‧ arrow

124‧‧‧illumination point

125‧‧‧ line

125"‧‧ ‧ specular reflection

126‧‧‧ Surface defects/defects

127‧‧‧ arrow

130‧‧‧Detector/Signal Detector

131‧‧‧Detector Path

132‧‧‧Optics/front optics

133‧‧‧Analyzer

134‧‧‧ Spectrometer

136‧‧‧Sensor/Camera Sensor/Sensor Detector

140‧‧‧Second light source/broadband light source/light source

141‧‧‧Line/Broadband illumination

142‧‧‧Illumination line/broadband illumination line/line/excitation line

143‧‧‧Broadband light/reflected broadband light

144‧‧‧ fiber optic

145‧‧‧ arrow

146‧‧‧ cylindrical lens

150‧‧‧ computer

152‧‧‧ processor

154‧‧‧ memory

158‧‧‧ display

160‧‧‧Input device

162‧‧‧Non-temporary computer usable media/computer readable storage media/computer usable media

164‧‧‧Communication埠

202‧‧‧ peak

204‧‧‧ peak

206‧‧‧ peak

402‧‧‧Long elliptical cylindrical mirror / elliptical mirror / elliptical cylindrical mirror / optics

403‧‧‧slit

406‧‧‧Excitation laser beam/laser beam/beam/excitation beam

407‧‧‧ Optical signal / resulting optical signal

409‧‧‧Mirror-reflected light

410‧‧‧ line

412‧‧‧Light pipe

414‧‧‧Linear signal receiver

416‧‧‧Signal output / rectangular signal output

418‧‧‧ fiber optic

452‧‧‧Filter/Optical Filter

454‧‧‧ Spectrometer

456‧‧‧CCD or CMOS camera sensor array

458‧‧‧ data acquisition device

462‧‧‧Photomultiplier tube / sudden photodiode

502‧‧‧Long cylindrical lens / cylindrical lens / lens / optics

Line 510‧‧

N‧‧‧ normal/surface normal

X‧‧‧ axis

X1‧‧‧ Position/Discrete Position

X2‧‧‧ Position/Discrete Position

X3‧‧‧ Position/Discrete Position

X4‧‧‧ Position/Discrete Position

X5‧‧‧ Position/Discrete Position

Y‧‧‧ axis

Z‧‧‧ axis

Α1‧‧‧incident angle/non-zero incident angle/angle

Α2‧‧‧incident angle/non-zero incident angle/illegal line incident angle/angle of view

33‧‧‧ viewing angle / non-zero angle

Λ‧‧‧wavelength

1 illustrates an optical metrology device capable of simultaneously detecting any combination of photoluminescence light, specular reflection, and scattered light of a broad band of light across a line of the same width.

2A is a top plan view of a surface of a sample having an illumination point from a first source of light that scans across the width of the sample to produce an illumination line, and the illumination line moves across the sample.

2B depicts a top view of a sample with an illumination line from a second source and the illumination line moving across the sample.

3A and 3B are respectively a perspective view and a side view of a dark channel observation of scattered light by the optical metrology device of FIG. 1.

4A and 4B respectively illustrate bright field reflection observation by the optical metrology device of FIG. One of a perspective view and a side view, wherein a narrow band source and associated optics are omitted for clarity.

5A and 5B are respectively a perspective view and a side view showing the excitation of the sample by scanning the illumination beam and the collection of the emitted photoluminescence light by the optical metrology device of FIG. 1.

Figure 6 illustrates the Lambertian characteristics of an incident illumination beam and emitted photoluminescence.

7 and 8 respectively illustrate a side view (along the YZ plane) and a front view (along the XZ plane), the side view and front view showing dark field scattering by the optical metrology device of FIG. Simultaneous collection of radiation, bright field reflected radiation, and photoluminescent light.

Figure 9 illustrates signal separation of three spectral channels (dark field scattered radiation, bright field reflected radiation, and photoluminescent light) imaged by a 2D sensor array.

Figure 10 is a flow chart showing one of the methods of optical metrology data from a plurality of light sources.

11 and 12 illustrate side views (along the Y-Z plane) of an alternate configuration of the optical metrology device of FIG. 1.

Figure 13 is a perspective view of one of the oblong cylindrical mirrors that can be used to receive photoluminescent light from a sample emission.

Figure 14 depicts a side view (along the Y-Z plane) of an elliptical mirror that collects photoluminescence or scattered radiation from a sample.

Figure 15 depicts a perspective view of one of the long cylindrical lenses that can be used to receive photoluminescence from sample emission.

Figure 16 depicts a side view (along the Y-Z plane) of a cylindrical lens that collects photoluminescence or scattered radiation from a sample.

17A and 17B illustrate a receiving end and an output end of a light guide of one of a plurality of optical fibers, respectively.

Figure 18 illustrates the supply of collected light to a light pipe comprising one of the detectors of a spectrometer.

Figure 19 illustrates a light pipe that provides collected light to one of the detectors including a photomultiplier tube (PMT) or a astigmatism diode (APD).

Figure 20 illustrates a side view (along the Y-Z plane) of simultaneous collection of dark field scattered radiation, photoluminescent light, and optionally bright field reflected radiation by an optical metrology device using an elliptical mirror.

Cross-reference to related applications

This application claims priority to U.S. Application Serial No. 15/178, 484, filed on Jun. Part of the continuation case, U.S. Application No. 14/936,635, which is incorporated herein by reference in its entirety, U.S. Application Serial No. 14/091,199 (now U.S. Patent No. 9,182,351), which is based on 35 USC 119 The priority of U.S. Provisional Application No. 62/253,092, filed on Nov. 9, 2015, the entire disclosure of which is hereby incorporated by reference.

1 illustrates an optical metrology device 100 capable of simultaneously detecting any combination of photoluminescent light, specular reflection, and scattered light of a broad band of light across a line of the same width. The sample is moved in a single direction to sweep the line across the sample so that data can be quickly collected from each location on the surface of the sample.

Metering device 100 includes a first source 110 that can be, for example, a narrowband illumination source, such as a laser. By way of example, the light source 110 can be a high intensity laser, such as having a peak wavelength of 405 nm and a range of 1 mW to 500 mW, depending on the photoluminescence efficiency of the sample being measured and the desired signal intensity to be recorded by the detector. One of the power continuous wave (CW) lasers. If desired, more than one laser can be used to create multiple narrow combinations for source 110 Band wavelength. Other laser wavelengths (such as 266 nm, 355 nm, 375 nm, 532 nm, 640 nm, or 830 nm, and other wavelengths not listed herein) may additionally or alternatively be used by way of example. The laser(s) used as source 110 can operate in a continuous wave or Q switching mode of operation. If a Q-switched (QS) laser is used for sample excitation, the instantaneous power (ie, the power during the pulse) can be much larger (eg, in the range of a few kilowatts (2.5 kW)).

A lens system comprising one of the optical devices 112 is used to generate an illumination spot on the surface of the sample 101 with the illumination beam 114. The illumination spot produced by illumination beam 114 should have a size and/or power density to excite photoluminescence in sample 101. By way of example, the spot size can range between 50 [mu]m and 1 mm and/or have a power density ranging between about 0.1 W/cm2 and 10<^8>W/cm<^2> . For example, if a CW 1 mW laser is focused to a point of about 1 mm, the power density is about 0.127 W/cm ² . A laser of the same CW 1 mW focused to a point of 50 microns will give a power of 50 W/cm ² . If a higher power 500mW CW laser is used and it is focused to a point of 1mm, then a power density of 63W/cm ² and the same laser focused to 50μm will result in 2.5*10 ⁴ W/cm ² Power density. Thus, a typical power density of the laser system in the CW 0.1W / cm ² to 2.5 * 10 ⁴ W / cm ² of the range. In the case of a sample-excited Q-switched laser, the power density is very different. For example, at an average power of 1 mW and a pulse duration of 10 nanoseconds (10*10 ^-9 s) and a repetition rate of 100 kHz, the instantaneous power can be as high as 1 W, and the corresponding power density at a point of 1 mm 127W/cm ² . When the same laser is used with an average power of 500 mW and is focused to a 50 μm dot size, the instantaneous power can reach, for example, 2.5*10 ⁷ W/cm ² .

The lens system can further include a scanning system 116 including a scanning mirror 118 and a fixed mirror 120 for scanning the width of the surface of the sample 101 across the surface of the sample 101 into an illumination line 122 (shown as Oriented in the X direction). Depending on scanning resolution and sensing The scan speed/frequency of the scanning system 116 is adjusted by the read speed. For example, the frequency can be, for example, in the range between 50 Hz and 100 Hz, but can vary from one of 1 Hz to 10 kHz or higher. Scanning mirror 118 is moved to cause the illumination spot to scan across the surface of sample 101 and may be, for example, a (swing) galvanometer mirror or a rotating polygon mirror. By way of example, FIG. 2A depicts a top view of the surface of the sample 101 with an illumination spot 124 generated by the illumination beam 114 (FIG. 1) having a scan across the width of the sample (as indicated by arrow 127). As depicted by line 121 in FIG. 1, scanning system 116 causes illumination beam 114 to scan across sample 101 in a plane that forms a non-zero incident angle α1 with respect to surface normal N. Therefore, the illumination line 122 is incident on the surface of the sample 101 at an illegal line incident angle. It should be understood that the illumination line 122 is additionally scanned across the surface of the sample 101 by moving the sample 101 in the Y direction (as illustrated by arrow 123) by the stage 104 (FIG. 1) such that the illumination line 122 can be incident on the surface of the sample 101. In all positions.

It should be understood that FIG. 1 illustrates one configuration of the narrowband illumination source 110 and associated optics (including the scanning system 116), although other configurations may be used if desired. For example, while the use of the fixed mirror 120 facilitates simplified system alignment, the fixed mirror 120 can be removed from the scanning system 116 if desired, and the light source 110, lens 112, and scanning mirror 118 can be repositioned such that the illumination beam 114 The sample 101 is directly illuminated without the need to redirect the mirror 120. Again, it should be understood that the optical device 112 can focus the illumination beam 114 as one of the illumination spots 124 on one of the surfaces of the sample 101. If the illumination beam 114 is focused on one of the sample planes that coincides with the surface of the sample 101, as the illumination beam moves along the illumination line 122, the illumination point may become slightly defocused, but the signal intensity variation due to defocus may be Signal processing compensation within the computer 150. Alternatively, optical device 112 can collimate illumination beam 114 by way of example. If desired, the collimated illumination beam 114 can be focused onto the surface of the sample using an optional F-theta lens 111 (shown in phantom in Figure 1). Furthermore, if necessary, the collimated illumination beam 114 can be incident on the sample 101 as an illumination point without being focused. On the surface, there is associated loss associated with one of the resolution and excitation conditions.

By scanning the illumination spot 124 across the sample 101 to produce the illumination line 122, one of the high power densities of the incident light can be maintained. Thus, the illumination beam from source 110 imparts energy to the material of the sample via "photoexcitation", thereby producing photoluminescent light that is emitted from the sample along illumination line 122. Additionally, surface defects on the sample 101, such as scratches, particles, epitaxial growth defects (eg, stacked lamella or clumps), may scatter the illumination beam 114 as the illumination beam 114 scans along the illumination line 122.

As depicted by line 121 in FIG. 1, scanning system 116 causes illumination beam 114 to scan across sample 101 in a plane that forms a non-zero incident angle α1 with respect to surface normal N. Therefore, the illumination line 122 is incident on the surface of the sample 101 at an illegal line incident angle.

The optical metrology device 100 includes a light detector 130 that receives light from the surface of the sample 101 along a detector path 131. The detector path 131 has a non-zero angle α3 with respect to the surface normal N. Therefore, as shown in FIG. 1, the detector 130 has a viewing angle α3 that is different from the incident angle α1 of the illumination line 122. Therefore, the specular reflection of the illumination beam 114 from the surface of the sample 101 does not enter the detector path 131. Typically, the photoluminescent signal is several orders of magnitude longer than the reflected radiation signal. By using the angle of incidence α1 and the angle of view α3, the optical metrology device 100 allows the illumination beam 114 to be reflected from the specular surface of the sample 101 without interfering with the photoluminescence signal received by the detector 130, thereby avoiding the need to filter the reflection of the illumination beam 114. Moreover, since the illumination beam 114 is not filtered, the detector 130 can receive light scattered by surface defects without receiving the illumination beam 114, i.e., achieve dark field observation. It will be appreciated that the sample 101 will have a different wavelength than the illumination beam 114 itself in response to the photoluminescence generated by the excitation of the illumination beam 114. Therefore, the wavelengths from the photoluminescent light and the scattered light can be dispersed into different spectral channels. Therefore, the optical metrology device 100 can be used to simultaneously detect surface configuration defects and photoluminescence. In addition, by using the scanning system 116, the light source 110 can Acting as a line of illumination where there is no loss of power density or uniformity of illumination along the line with the use of a cylindrical lens or cylindrical mirror.

The detector 130 includes an optical device 132, a spectrometer 134, and a sensor 136. The sensor 136 includes a two-dimensional CCD or CMOS sensor array. Light collected along detector path 131 (e.g., photoluminescent or scattered light) is collected by front optics 132 and then passed through a narrow entrance slit aperture in spectrometer 134. The field of view of spectrometer 134 is limited by the entrance slit, which matches the orientation of illumination line 122. Thus, the entrance slit of detector 130 (or more specifically, spectrometer 134) is aligned with illumination line 122 and superimposes broadband illumination line 142 (discussed below), ie, entrance slits and illumination lines 122 and 142. All belong to the same plane, while the illumination lines 122 and 142 are superimposed on each other, and the entrance slit to the detector 130 is parallel to the illumination lines 122 and 142. Spectrometer 134 disperses the spectrum of the received light, and sensor 136 at the exit of spectrometer 134 records with a two-dimensional (2D) sensor array and produces a resulting image frame, with one of the sensor arrays first The dimension represents the spatial location along the illumination line 122, and one of the second dimensions of the sensor array represents spectral information. Spectrometer 134 separates the wavelengths of the emitted photoluminescent light and separates the scattered light along one dimension of the 2D sensor array while recording the position along illumination line 122 by the second dimension of the 2D sensor array. For example, one point along the illumination line 122 can emit one of the maximum photoluminescence of 460.3 nm while another point on the illumination line 122 can emit one of the maximum photoluminescence of 460.8 nm. Thus, spectrometer 134 separates the wavelengths of the emitted photoluminescent light to perform spectral photoluminescence imaging.

The metering device 100 further includes a second light source 140, which may be, for example, a broadband illumination source, such as a halogen source, the second source 140 comprising a different wavelength than the first source 110 or a sample 101 response The wavelength of light at the wavelength of the photoluminescent light emitted by the excitation of the illumination beam 114. Broadband radiation sources (sometimes referred to as a "white" source) are formed as a sample The illumination line 122 on the surface of the 101 is aligned and superimposed on the illumination line 142. As shown, illumination line 142 can be generated, for example, using a series of optical fibers 144 (only one of which is shown coupled to light source 140). By way of example, the second light source 140 having a series of optical fibers 144 can be a light product manufactured by Schott North America, Inc. Light from the plurality of optical fibers 144 is formed as an almost quasi-linear beam by means of a cylindrical lens 146. 2B illustrates a top view of sample 101 with illumination line 142 from second source 140.

As depicted in FIG. 1, the broadband light from source 140 illuminates the surface of sample 101 along a plane depicted by line 141, which has a non-zero incident angle [alpha]2 with respect to surface normal N. Therefore, the illumination line 142 is incident on the surface of the sample 101 at an illegal line incident angle α2. It should be understood that the illumination line 142 is additionally scanned across the surface of the sample 101 (along with the superimposed illumination lines 122) by the stage 104 (FIG. 1) (as depicted by arrow 145 in FIG. 2B) such that the illumination line 142 can It is incident on all positions on the surface of the sample 101. The incident angle α2 is different from the incident angle α1 and has a mark different from the mark of the angle α1, that is, the illumination line 142 is incident on the surface of the sample from one direction opposite to the illumination line 122, and has a different incident angle. However, the angle of incidence α2 of the illumination line 142 is the same as the angle of view α3 of the detector path 131 but the value is opposite, that is, the angle of view α2 = -α3. Thus, the viewing angle of the detector 130 is tuned to the angle of incidence of the illumination line 142, and thus, the specular reflection of the broadband light along the illumination line 142 is also aligned with the field of view of the spectrometer 134. Therefore, both the illumination line 122 generated by the light source 110 and the illumination line 142 generated by the light source 140 are received by the detector. Spectrometer 134 separates the wavelength of the specular reflection of the broadband illumination along illumination line 142 into one dimension of the 2D sensor array while being represented by the second dimension of the 2D sensor array along illumination line 142 (and the illumination line) 122) Location.

The broadband light source 140 can use a wavelength of light different from the wavelength(s) used by the first source 110 and the wavelength(s) of photoluminescent light emitted by the sample 101 such that the spectrometer 134 can The wavelength of the broadband light from the reflection is separated from the wavelength of the scattered light and the wavelength of the photoluminescent light. Therefore, the first light source 110 and the second light source 140 can be used together with the detector 130 to simultaneously detect the position of the photoluminescence light caused by the excitation of the illumination beam 114 together with the illumination lines 122 and 142 and the illumination beam 114. Dark field scattering and spectral information from bright field reflections from source 140. By way of example, based on the wavelengths of the narrowband source 110, the broadband source 140, and the emitted photoluminescent light, the optical metrology device 100 can use a range of wavelengths between 400 nm and 1,000 nm (ie, in the range of 600 nm). The detector 130 can divide the received light into, for example, 1200 wavelengths, that is, the number of pixels in the spectral dimension of the sensor array, and thus, the detector 130 can have a spectral resolution of 0.5 nm. . Of course, other spectral resolutions, as well as ranges of optical or optical wavelengths and the number of wavelengths detected by detector 130, may be used if desired.

Moreover, the wide-band light that is specularly reflected from the surface of the sample 101 is guided to the detector 130 without mechanical repositioning of the detector 130, so that the detector 130 can simultaneously or closely collect the surface reflection, scattering, and Photoluminescence signal without any delay in mechanical repositioning of any device optics subassembly. Of course, if desired, the first light source 110 and the second light source 140 can be used in close proximity such that the detector 130 cannot simultaneously receive light from both of the illumination lines 122 and 142.

The sample 101 is held on a linear stage 104 that can translate the sample 101 in one direction other than the orientation of the illumination lines 122 and 142. For example, the orientation of illumination lines 122 and 142 can be in one direction (eg, the X direction) orthogonal to the direction of travel (eg, the Y direction) of linear stage 104. The stage 104 translates the sample 101 such that the illumination lines 122 and 142 are placed at multiple locations across the sample 101 (as depicted by arrows 123 and 145 in Figures 2A and 2B) and are repeatedly illuminated at each new location. Spectral imaging of lines 122 and 142. The process of imaging and moving the sample 101 is repeated to cause the illumination lines 122 and 142 to scan across the sample 101, resulting in a series of 2D image frames. If necessary, the stage 104 can move the sample 101 stepwise or continuously move the sample 101, so that the data Acquisition is performed continuously (e.g., by high frequency scanning of one of the illumination points 124) without requiring the Y-axis motion to stop at each line. For example, when one of the illumination points 124 is scanned at a high frequency (eg, 500 Hz) with one of the Y-axis relative to the low-speed stage motion and the low-speed collection of the image frame (eg, 100 Hz), the illumination beam 114 is directed to Each given image frame scans the illumination line 122 several times (e.g., five times in a given example), which provides improved signal averaging. The speed of movement of the stage along the Y axis can be expressed in millimeters per second and depends on the desired resolution along the Y direction. For example, when the Y speed is 20 mm/s and the frame rate is 100 frames/second, the Y resolution is 20 mm/s divided by 100/s equals 0.2 mm.

Therefore, in a data capture operation, the optical metrology device 100 is capable of simultaneously collecting spectral photoluminescence and spectrally scattered radiation and spectrally reflected radiation signals from the line illumination portion of the sample 101, and is movable along a single axis and repeatedly performing data. Take the operation to get the data of the entire sample surface. In one embodiment, the entire sample surface is acquired by moving the sample 101 beneath the illumination lines 122 and 142 in the Y direction with a linear stage. However, in another embodiment, the data may be collected by rotating the sample 101 beneath the illumination lines 122 and 142 in a Θ (angle) direction (as illustrated by a dashed arrow in FIG. 1) with a rotating stage. In both embodiments, the sample 101 is moved along only one axis (Y or Θ (both non-essential)), resulting in a high speed measurement. In contrast, conventional systems acquire data from a single illumination point and must move the sample along two axes to obtain data for the entire sample surface. Thus, optical metrology device 100 uses a single unidirectional stage rather than two linear stage systems or linear and rotary stage systems. Furthermore, data acquisition is accelerated by the elimination of the required stage motion along the X-axis.

It should be understood that the illumination between the illumination lines 122 and 142 and the sample 101 is relative, and therefore, if desired, the stage 104 can remain stationary and can be used to align, for example, the light source and associated optics with respect to Sample 101 moves one of the stages or other suitable components to illuminate lines 122 and 142 Move laterally in the Y direction or in the Θ direction.

The plurality of image frames generated by the detector 130 can be received by the computer 150 as the moving sample 101 and the spectral information of the line illumination portion from the sample 101 are received, and the computer 150 can store the plurality of image frames as three-dimensional (3D). ) Data cube. The 3D data cube is contained in two dimensions of space (eg, one dimension is along the position of the illumination lines 122 and 142 (X-axis) and the other dimension is the position of the line across the sample (Y-axis)) and represents spectral information. One of the third dimensions. The detector 130 is coupled to provide image data to a computer 150. The computer 150 includes a processor 152 having a memory 154 and a user interface including, for example, a display 158 and an input device 160. One of the non-transitory computer usable media 162 having embodied computer readable code can be used by computer 150 to cause the processor to control metering device 100 and perform the functions comprising the analysis described herein. Data structures and software codes for automatically implementing one or more of the actions described in this detailed description can be implemented by a person skilled in the art in accordance with the present invention and stored on, for example, a computer readable storage medium 162, Storage medium 162 can be any device or medium that can store code and/or material for use by a computer system, such as processor 152. Computer usable media 162 may be, but is not limited to, magnetic and optical storage devices such as disk drives, magnetic tapes, optical discs, and DVDs (digital versatile discs or digital video discs). A communication port 164 can also be used to receive instructions for programming the computer 150 to perform any one or more of the functions described herein and can represent any type of communication connection (such as to the Internet or any other). Computer network). In addition, the functions described herein may be embodied in whole or in part in a circuit of a special application integrated circuit (ASIC) or a programmable logic device (PLD), and may be used to form an ASIC or as described herein. One of the PLDs is a computer-understandable descriptor language.

By way of example, the computer 150 can use the photoluminescence signal received from the detector 130 for each position on the surface of the sample 101 as stored in the 3D data cube, and generate the sample 101. One photoluminescent image (or mapping). The photoluminescence image can be mapped, for example, to one of the signal intensities of the photoluminescent signal. Examination of the photoluminescence intensity image can be used for program control to ensure that all parts of the sample 101 meet the desired specifications. For example, where sample 101 contains a fabricated light emitting diode (LED) wafer, inspection of the photoluminescent material (eg, in the form of a photoluminescence image) can be used to ensure that each LED will have Appropriate brightness. Similarly, photoluminescence intensity images can be used for defect segmentation and for predicting yield loss based on the presence of local low photoluminescence signals that can result in substandard devices at the back end process. If desired, the photoluminescent signal can be processed to produce additional images or maps. For example, a peak lambda image can be generated to show the distribution of peaks λ on the surface of the sample, where the peak lambda has the wavelength of maximum photoluminescence at any given point in its lower image or map. Thus, for example, one point on the surface of the sample can emit a maximum photoluminescence of 460.3 nm, while another point on the surface of the same sample can emit one of the maximum photoluminescence of 460.8 nm, which is clearly visible with a peak λ image. By using spectrophotoluminescence imaging, photoluminescent light of different wavelengths emitted by the sample can be identified. Thus, the optical metrology device 100 can be used for program control to ensure that all points on the surface of the sample emit photoluminescence over a predefined range of wavelengths. Additionally or alternatively, the photoluminescent signal can be converted to a full width at half maximum (FWHM) image that exhibits a FWHM value for each peak λ at any given point on the sample. By way of example, FWHM images can be used to ensure that light-emitting diodes (LEDs) fabricated with samples emit light in a predefined wide (band) spectral range. The photoluminescence signal can be processed to produce an image of the sample 101 instead of the photoluminescence intensity, peak lambda, and FWHM images. For example, the photoluminescent signal can be processed or analyzed to produce different qualities, such as, for example, one of the photoluminescence intensities at a given fixed wavelength, which map is different from the maximum photoluminescence intensity map. Furthermore, the image or mapping of interest can be generated by combining multiple sets of images, such as those images discussed (eg, by pixel-by-pixel multiplication). Therefore, light is emitted The optical signal can be processed to generate other desired images of the sample 101 based on the recorded photoluminescent signal or otherwise analyzed for program control during manufacture of the sample.

Additionally, computer 150 can process the received reflected wideband signal to determine one of the characteristics of sample 101 at a plurality of locations and to generate a map of that characteristic. For example, the layer thickness can be calculated based on the spectral response associated with the reflection of the broadband light, and thus, the received reflected broadband signal can be used to determine the thickness of the spot on the surface of the sample and can produce an epitaxial layer thickness image (or map). Thus, the optical metrology device 100 can be used to monitor the thickness of the epitaxial layer at any given point on the surface of the sample, which can be used to ensure that the measured thickness is within a predefined range of a given epitaxial growth procedure. Additionally, using the received scattered light, computer 150 can produce a dark field image of the surface of sample 101 to expose surface defects that can be associated with scratches, particles, epitaxial growth defects (eg, stacked defects or Chimney) and so on.

3A and 3B are respectively a perspective view and a side view of the dark channel observation of the scattered light by the optical metrology device 100. As shown, light source 110 produces illumination line 122 on the surface of sample 101 using optical device 112 and scanning system 116 including scanning mirror 118 and fixed mirror 120. If the sample is free of defects, the light will be mirrored as shown by line 125 from the surface of sample 101 and will not be detected by camera sensor 136. When a surface defect 126 is present on the sample 101, one portion of the illumination beam 114 is scattered as the illumination beam 114 is scanned over the defect 126. The scattered light along the detector path 131 is received by the detector 130 and passes through the slit aperture into the spectrometer 134. The field of view of spectrometer 134 is limited by a slit aperture, and thus, sensor 136 only images illumination line 122. The specular reflection of the illumination beam 114 is not received by the spectrometer 134. Spectrometer 134 typically separates light into a wavelength grading bin in the spectral dimension of the 2D sensor array. However, the scattered light is derived from the narrowband source 110, and thus the scattered light received by the detector 130 is deflected by the spectrometer 134 to correspond to the wavelength(s) of the source 110 recorded by the sensor 136 (if Dry) in the grading box. The effectiveness of the scattered light channel can be further modified by adding a polarizer and analyzer to the optical path of the narrowband illumination beam 114. By way of example, a beam polarizer 119 can be placed downstream of the light source 110 (eg, between the lens 112 and the mirror 118), and the analyzer 133 can be combined with the front optics 132.

4A and 4B are respectively a perspective view and a side view of bright field reflection observation by optical metrology device 100, with light source 110 and associated optics omitted for clarity. The broadband light source 140 illuminates the sample 101 along an illumination line 142 that extends across the width of the sample 101 along one of the orientations of the entrance slits of the matching spectrometer 134. Thus, light from the source 140 that is specularly reflected from the surface of the sample 101 passes through the slit aperture into the spectrometer 134. Within spectrometer 134, the broadband light is separated (graded) into a series of wavelengths that are recorded by a 2D sensor array in sensor 136, where one dimension of the 2D sensor array represents spectral information and the other The dimension represents spatial information along the illumination line 142. Thus, the configuration of the broadband light source 140 is one of the bright field modes of operation in which the illumination line 142 can be spectrally imaged for one of the widths of the sample 101. The use of an illegal line incident angle for bright field viewing facilitates simplification of uniform illumination and spectral imaging of sample 101 along illumination line 142.

5A and 5B are respectively a perspective view and a side view showing the excitation of the sample 101 by scanning the illumination beam 114 and the collection of the emitted photoluminescence light by the optical metrology device 100. Similar to FIGS. 3A and 3B above, light source 110 produces illumination line 122 on the surface of sample 101 using optics 112 and scanning system 116, which may include scanning mirror 118 and fixed mirror 120. As discussed above, the fixed mirror 120 can be removed or replaced and/or an F-theta lens can be used. The specularly reflected light from the illumination beam 114 is depicted by line 125. However, another portion of the light from the illumination beam 114 enters the sample 101 and is absorbed. The absorbed energy produces an electron-hole pair that emits photoluminescence along the excitation line (ie, illumination line 122) immediately after recombination. Light. The photoluminescence light generated from the excitation line emission exits the sample 101 in a plurality of directions having a near Lambertian property. By way of example, FIG. 6 illustrates the Lambertian characteristics of the incident illumination beam 114 and the emitted photoluminescence (light that is not specularly reflected in FIG. 6). Additionally, since the illumination beam 114 is scanned across the width of the sample 101 along the illumination line 122, as depicted in Figure 5A, photoluminescent light is emitted along the excitation direction. The slit apertures passing through the spectrometer 134 receive the emitted photoluminescent light along the detector path 131, wherein the light is deflected by the spectrometer 134 to a wavelength(s) corresponding to the photoluminescent light recorded by the sensor 136. In the (several) classification box.

7 and 8 respectively illustrate a side view (along the YZ plane) and a front view (along the XZ plane), the side view and front view showing dark field scattered radiation by the optical metrology device 100, Simultaneous collection of bright field reflected radiation and photoluminescence light. As illustrated, the illumination beam 114 produces scattered light 115 and excites the photoluminescent light 117, which is received by the spectrometer 134 along with the reflected broadband light 143.

By way of example, FIG. 9 illustrates signal separation of three spectral channels (dark field scattered radiation, bright field reflected radiation, and photoluminescent light) imaged by the 2D sensor array of the sensor detector 136. As shown, the 2D sensor array includes a first dimension (X-axis in FIG. 9) representing spatial information along illumination lines 122 and 142, wherein another dimension represents spectral information about signal strength (ie, Wavelength λ). In FIG. 9, the scattered laser beam signal is depicted by peak 202, the photoluminescent signal is depicted by peak 204, and the reflected broadband beam signal is depicted by peak 206.

Therefore, as shown in FIG. 7, FIG. 8, and FIG. 9, the detector 130 can simultaneously record one of the photoluminescence light and the broadband light 143 generated in the sample 101 in response to the excitation by the illumination beam 114. Field reflection. If desired, the detector 130 can further record a dark field scatter of the illumination beam 114 due to a defect on the sample, such that if desired, three separate signals are simultaneously imaged. The three signals can be recorded simultaneously along the entire width of the sample 101 in a macro mode, rather than as is conventional Execution is recorded point by point in a microscopic or recorded in a narrow field of view. Again, a detector 130 is used to collect all three signals such that there is no spatial or temporal shift between the three signals. A spectrometer 134 splits the signal into three different spectral information channels, i.e., uses a 2D sensor array sensor of the detector 130 to spectrally separate (record) the signal spectrum into different wavelength bins (sensor pixels). in. It should be understood that the image frame shown in FIG. 9 is for one position of the illumination lines 122 and 142 along the Y axis in FIG. 1, and the sample 101 is moved in the Y direction with the stage 104 to make the illumination line The 122 and 142 scans span the sample, and the sensor 136 will generate a plurality of image frames for each of the illumination lines 122 and 142 along the Y-axis in FIG.

Figure 10 is a flow chart showing one of the methods of optical metrology data from a plurality of light sources. As shown, a first surface (302) is illuminated at a first angle of incidence with a first source along a first illumination line having a direction along one of the first directions. The sample emits photoluminescent light from the first illumination line in response to excitation by light from the first source. By way of example, as discussed above, the sample can be illuminated, for example, using a narrowband source 110 and scanning across the sample to produce an illumination beam of one of the first illumination lines. A surface (304) of the sample is illuminated with a second source at a second angle of incidence along a second illumination line having one of the first illumination lines oriented along one of the first illumination lines. The second incident angle is different from the first incident angle, and the second light source is a broadband light source. Broadband light is reflected from the surface of the sample. Detecting, by a two-dimensional array, specular reflection of the photoluminescent light emitted by the sample along the first illumination line and the broadband light from the second illumination line, the two-dimensional array having a representation corresponding to the first illumination line and A first dimension of spatial information of the location of the second illumination line and a second dimension (306) representing spectral information. The specular reflection of light from the first source along the first illumination line may not be detected. The superimposed first and second illumination lines are moved across a surface of the sample (308) in a second direction that is different from the first direction. For example, the first direction and the second direction can be orthogonal. The sample 101 can be moved relative to the illumination line by a linear stage or a rotating stage The first illumination line and the second illumination line are moved. If desired, the first and second illumination lines can be moved relative to the sample 101 by a stage (e.g., by moving the source and associated optics relative to the sample 101 that can remain stationary). The first illumination line and the second illumination line move. As the first illumination line and the second illumination line move across the surface of the sample, a three-dimensional data cube is generated using the detected photoluminescence light and the specular reflection of the detected broadband light, the three-dimensional data cube having a representation sample The two dimensions of the spatial information of the surface and the third dimension of the spectral information (310).

Additionally, as discussed above, a portion of the light from the first source can be scattered as scattered light from surface defects on the sample and the scattered light can be detected by a two-dimensional array, wherein the three-dimensional data cube additionally includes the detected scattered light. The use of scattered light in a three-dimensional data cube produces a surface defect image of one of the surfaces of the sample. Alternatively, a photoluminescence image of the surface of the sample can be generated using the detected photoluminescence light in a three-dimensional data cube. For example, the photoluminescence image of the sample surface can be, for example, a photoluminescence intensity image, a photoluminescence peak lambda image, or a photoluminescence full width at half maximum (FWHM) image. In addition, for a plurality of positions on the surface of the sample, the detected specular reflection of the broadband light in the three-dimensional data cube can be used to determine one of the characteristics of the sample, and the sample characteristics for the plurality of positions can be used to generate the surface of the sample. One image. For example, the epitaxial layer thickness of the sample 101 can be determined at a plurality of locations on the surface of the sample 101, and an epitaxial layer thickness image (or map) can be produced. As discussed above, data from a three-dimensional data cube can be analyzed for program control during sample manufacturing.

By way of example, FIG. 11 illustrates a side view of an optical metrology device 100', except that the narrowband illumination beam 114' is shown as being incident on the same N-side as the broadband illumination 141, the optical metrology device 100' and The optical metrology device 100 illustrated in Figure 7 is similar. Therefore, although the narrow-band illumination beam 114' and the broadband illumination 141 are incident on the surface of the sample 101 from the same side of the normal line N, Using different angles of incidence, the specular reflection 125' of the narrowband illumination 114' does not follow the detector path 131, thereby enabling dark field mode measurements. As can be seen in Figure 11, the angle of incidence of the illumination beam 114' is greater than the angle of incidence of the broadband illumination 141 relative to the normal N, although this is not strictly required. By way of example, FIG. 12 is similar to FIG. 11 and depicts an optical metrology device 100" that is configured such that the narrowband illumination beam 114" has one relative to the normal N compared to the broadband illumination 141. The smaller incident angle, while the narrow-band illumination 114" specular reflection 125" still does not follow the detector path 131, enabling dark field mode measurements.

A significant challenge for one of the wafer inspection equipment designers is to achieve photoluminescence or reflection or scattering at high resolution (a few hundred microns per pixel) at high speed (tens of wafers per hour) with high signal collection efficiency. Full wafer imaging of light. To achieve high measurement speeds, low numerical aperture (NA) objectives and large field of view (FOV) configurations are sometimes used to achieve signal acquisition from the entire sample size in one signal acquisition. By general definition, the numerical aperture is equal to NA = n * sin(θ), where n is the refractive index of the medium in which the lens is used (air is 1.00) and θ is the maximum half angle of the light that enters the lens through the lens aperture. Thus, for a typical large FOV imaging system (having a 20 mm diameter lens and a typical object-to-lens distance of about 400 mm), the numerical aperture can be calculated as NA = 0.025. Low NA objectives and large FOV configurations result in low signal collection efficiency and low instrument sensitivity, since in this configuration the optics to sample distance must be large. A large optical device to sample distance results in substantial loss of photoluminescence or scattered light radiation. Higher numerical aperture objectives allow for shorter optics to sample distances, better signal acquisition, and higher instrument sensitivity, however, at the expense of reducing the FOV of the optics. Therefore, the measurement speed becomes lower, because several measurements and image stitching must be applied to the reconstruction information at the full sample scale.

The embodiments described above use a laser beam to scan an illumination spot across a surface (eg, using a galvanometer mirror or a rotating polygon mirror) to excite the sample while using hyperspectral light. One of the spectrometer and camera system combinations provides a high measurement resolution and high speed based on the lens objective to detect photoluminescence or reflected or scattered radiation responses. To achieve a desired high measurement speed, low numerical aperture optics with sufficient field of view (up to 300 mm) for the entire sample can be used. This configuration allows for high speed measurements (eg, tens of wafers per hour) and high resolution (eg, on the order of hundreds of microns per pixel). However, the low numerical aperture of the objective lens can result in a large distance between the signal collecting device and the sample. Therefore, optical signal collection efficiency can be approved accordingly.

One way to improve the efficiency of optical signal collection, for example, is to achieve a reduction in optical device-to-sample distance by using higher numerical aperture optics, thereby increasing signal collection efficiency, however, this is a reduction. The optics field of view comes at the cost. By using higher numerical aperture optics, only a portion of the sample is scanned or viewed in one imaging cycle. Therefore, reconstructing an image of the entire sample requires a series of measurements and image stitching. This solution essentially results in a low measurement speed and a final low measurement throughput.

Thus, in another embodiment, a high NA optical device having, for example, one of the lengths of the desired image size, can be used to achieve a high collection efficiency of one of the optical signals. By using one of the signal collecting optics that extends for a length (eg, one-third, one-half, or the entire length of the illumination line), the signal collection optics can be placed close to the sample surface. It should be understood that if the signal collecting optics extends for one-third of the length of the illumination line, then the data for the entire image will require three scans, and similarly, if the signal collection optics extends for one-half the length of the illumination line, The data for the entire image will require two scans, thereby reducing the throughput of the signal collection optics relative to one of the entire lengths of the illumination line. For example, the distance from the signal collection optics to the sample and the width of the signal collection optics can be configured to produce a signal collection half angle θ sufficient to produce one of 0.4 or higher NA. High NA signal collection optics are reflective or refractive. Additionally, a light pipe can be used with the optics to provide the received light to the detector. The implementation achieves high resolution and high sensitivity signal collection with full sample size FOV, which allows for overcoming existing tradeoffs between high resolution, sensitivity, and speed.

For example, in one embodiment, to collect photoluminescence or scattered radiation across the excitation line 122 shown in FIG. 1, reflective optics such as a long elliptical cylindrical mirror can be used, for example, having a positive elliptical cylinder. One of the shaped surfaces. By way of example, FIG. 13 depicts a perspective view of one of the oblong cylindrical mirrors 402 that can be used to receive photoluminescence emitted from sample 101 or light scattered from sample 101. In the length direction, along the X-axis, the mirror 402 is flat, and in the width direction, along the Y-axis, the mirror 402 is elliptically curved with a high NA (ie, a short focal length). For example, the distance from the mirror to the sample can be 10 mm, and the contour of the mirror can be 10 mm, and therefore, the signal collection half angle θ is about 26 degrees, resulting in a NA = 0.45. The length of mirror 402, for example, can exceed a desired image size, such as a 300 mm sample size for current wafer technology. Mirror 402, along with collection optics and spectrometers (discussed below), can be used in place of detector 130 (e.g., as depicted in Figures 1, 3A, 4A, 7, 11, and 12).

Figure 14 depicts a side view (along the Y-Z plane) of an elliptical mirror 402 that collects photoluminescence or scattered radiation from the same 101. The mirror 402 can be placed close to (several millimeters to tens of millimeters) of the sample 404, resulting in a high collection efficiency of one of the optical photoluminescent or scattered radiation signals generated by exciting the laser beam 406. Mirror 402 can include a slit 403 or slits through which excitation laser beam 406 can pass. Alternatively, the excitation laser beam 406 can pass under the mirror 402, however, the use of a slit 403 allows for the use of a wider mirror, thus providing a higher NA and better signal sensitivity. The laser beam 406 is scanned across the wafer in the X direction, for example, using the scanning system 116 or the like shown in FIG. Mirror 402 collects optical signals from sample 404 at a wide angle at each desired spatial location along line 142 (along the X direction) (shown as positions X1, X2, X3, X4, and X5 in FIG. 13). 407, which results in a high instrument sensitivity. It should be understood that although depicted in Figure 13 The positions X1, X2, X3, X4, and X5 are scattered, but the beam 406 is continuously scanned across the sample 404, and optical signal 407 from all of the locations along line 142 is received by mirror 402. Due to the linear configuration of mirror 402 along the X direction, as depicted in Figure 13, where the excitation region is in the X direction of sample 404 across one of the lines 142 of the entire sample, the resulting optical signal 407 (e.g., from the sample) The 404 emitted photoluminescent radiation or the radiation scattered by the sample 404 is focused by an elliptical cylindrical mirror 402 into a line 410 having the same length as the excitation line 142. Excitation line 142 and line 410 can have the same length as mirror 402, i.e., one length beyond the desired image size (e.g., about 300 mm).

The sample 404 is excited in the form of one of the lines produced by moving the excitation beam 406 along the sample using the scanning system 116. In one configuration, to excite the sample 404, the excitation beam 406 can pass outside of the mirror 402 as the excitation beam 406 scans in the X direction. In one configuration, the excitation beam 406 can pass under or over the mirror 402. In another configuration, the elliptical cylindrical mirror 402 can include a slit along the length of the mirror such that the beam 406 can pass through the slit in the mirror 402 and can excite the sample 404 at any desired angle (including the normal angle).

The resulting optical signal 407 (as shown in FIG. 13) focused along line 410 is obtained by focusing photoluminescence or scattered radiation using an elliptical cylindrical mirror 402. The resulting optical signal 407 (which is focused along line 410) needs to be delivered to a detector 130 for the purpose of recording optical signals. However, the detector typically does not have an input aperture in the shape of a 300 mm long line. Thus, the resulting optical signal 407 (which is focused along line 410) should match the aperture of the detector 130 to produce minimal optical loss. In one embodiment, the resulting optical signal 407 focused by mirror 402 can be received by a light pipe 412 having a linear signal receiving end 414 (aligned with line 410 in FIG. 13) and having a detector The aperture of 130 matches one of the shapes of signal output 416. As shown, mirror 402 or light pipe 412 does not receive specularly reflected light 409. If desired, mirror 402 can include The specularly reflected light 409 passes through a slit (not shown).

In another embodiment, to collect photoluminescence or scattered radiation across the excitation line 122 shown in Figure 1, refractive optical means, such as an elongated cylindrical focusing lens, for example, having a positive cylindrical shape, may be used. a lens. By way of example, FIG. 15 depicts a perspective view of one of the elongated cylindrical lenses 502 that can be used to receive photoluminescence emitted from sample 101 or light scattered from sample 101. The cylindrical lens 502 can have a high NA, i.e., a short focal length. For example, if the diameter of the cylindrical lens is about 20 mm and the center of the lens is at a distance of 20 mm from the sample (i.e., the air gap between the sample and the lens is 10 mm), a NA = 0.45 is caused. The length of lens 502, for example, can exceed a desired image size, such as a 300 mm sample size for current wafer technology. Lens 502, along with collection optics and spectrometers (discussed below), can be used in place of detector 130 (e.g., as depicted in Figures 1, 3A, 4A, 7, 11, and 12).

Figure 16 depicts a side view (along the Y-Z plane) of a cylindrical lens 502 that collects photoluminescence or scattered radiation from the same 101. The cylindrical lens 502 can be placed close to (several millimeters to tens of millimeters) of the sample 101, resulting in a high collection efficiency of one of the optical photoluminescent or scattered radiation signals generated by exciting the laser beam 406. The laser beam 406 is scanned across the wafer in the X direction, for example, using the scanning system 116 or the like shown in FIG. Cylindrical lens 502 collects optical signal 407 from sample 101 at a wide angle along the length of line 142 (shown in Figure 15) on sample 101, which results in a high instrument sensitivity. Due to the linear configuration of the cylindrical lens 502 along the X direction, as depicted in Figure 15, where the excitation region is in the X direction of the sample 404 in the form of one of the lines 142 across the entire sample, the resulting optical signal 407 (e.g., The photoluminescence radiation emitted from sample 404 or the radiation scattered by sample 404 is focused by cylindrical lens 502 into a line 510 having the same length as excitation line 142. Excitation line 142 and line 510 can have the same length as cylindrical lens 502, i.e., one length beyond the desired image size (e.g., about 300 mm).

Sample 101 is excited in the form of one of the lines produced by moving the excitation beam 406 along the sample using scanning system 116. As shown, to excite the sample 101, the excitation beam 406 can pass under the cylindrical lens 502 as the excitation beam 406 scans in the X direction. The resulting optical signal 407 (as shown in FIG. 15) focused along line 510 is obtained by focusing photoluminescence or scattered radiation using a cylindrical lens 502. The resulting optical signal 407 (which is focused along line 510) needs to be delivered to a detector 130 for the purpose of recording optical signals. As discussed above, the resulting optical signal 407 (which is focused along line 510) should match the aperture of the detector 130 to produce minimal optical loss. In one embodiment, the resulting optical signal 407 focused by the cylindrical lens 502 can be received by a light pipe 412 having a linear signal receiving end 414 (aligned with line 510 in FIG. 15) and having The aperture of the detector 130 is matched to one of the signal outputs 416. As illustrated, cylindrical lens 502 or light pipe 412 does not receive specularly reflected light 409.

17A illustrates the linear signal receiving end 414 of the light pipe 412 for receiving the optical signal 407 from the optical device 402 or 502, and FIG. 17B illustrates the optical signal 407 for providing a rectangular signal output to the detector 130. 416. Light pipe 412 includes a plurality of optical fibers 418 between linear signal receiving end 414 and a rectangular signal output 416. As shown, the fiber 418 can be disposed at a linear signal receiving end 414 in a single column that matches the length of the optical signal 407 or matches the length of the optical device (eg, elliptical cylindrical mirror 402 or cylindrical lens 502). By way of example, 1298 fibers (each of which has a diameter of 0.245 mm) can be used to form a line approximately 318 mm long (slightly larger than 300 mm sample) to collect most of the signal from the edge of the sample. If desired, a different number of fibers or different fiber diameters can be used, or a different number of fiber trains can be used at the linear signal receiving end 414. Furthermore, if the sample sizes are different (eg, 200 mm), a different number of fibers can be used, for example, 891 fibers can be used to form a line about 218 mm long. Of course, if the length of the light pipe 412 is shorter than the length of the optical device 402 or 502, the optical signal One portion of 407 may not be received by light pipe 412, and thus, detector 130 and multiple paths may be required to obtain data for the entire sample. Fiber 418 is mechanically reconfigured from linear signal receiving end 414 to rectangular signal output 416. For example, as illustrated in Figure 17B, the fiber can be configured in several layers. For example, 1298 fibers on the linear signal receiving end 414 can be reconfigured on the spectrometer side to 118 layers multiplied by 11 layers to give the same number of fibers (118 x 11 = 1298 fibers). For a different sized sample (eg, a 200 mm sample) where there are 891 fibers on the linear signal receiving end 414, the 891 fibers can be reconfigured on the spectrometer side to 81 layers multiplied by 11 layers to give The same number of fibers (81 x 11 = 891 fibers). According to this example, the rectangular shape reconfigured to 81 times 11 layers sizing the light pipe 412 from the linear signal receiving end 414 by 218 mm (multiplied by 0.245 mm) to approximately 20 mm at the rectangular signal output 416 multiplied by 2.5mm (this is accepted by the detector 130). Thus, optical signal 407 is focused by optical device 402 or 502 into linear signal receiving end 414 and optical fiber 418 is used to provide an optical signal to rectangular signal output 416 coupled to detector 130. This configuration facilitates the delivery of optical signal 407 to signal detector 130, which ultimately converts the optical radiation into an electrical signal. Different shapes on the signal output 416 of the light pipe 412 can be used, such as rectangular, square or circular. Additionally, further focusing optics can be applied between the rectangular signal output 416 and the detector 130 to achieve even better matching as desired.

After exiting from light pipe 412, optical signal 407 can be further shaped by the exit optics to match the signal to the detector input. Various detection scenarios can be used depending on the desired end result. For example, detector 130 can use a spectrometer. As shown in FIG. 18, after exiting the light pipe 412, the optical signal 407 can be filtered by an optical filter 452 and provided to a slit of a spectrometer 454, wherein the light is dispersed into different wavelengths by a grating or prism, and Eventually delivered to the CCD or CMOS camera sensor array 456 and recorded by a data acquisition device 458, the data acquirer Piece 458 provides the data to processor 152 for analysis. Therefore, the detector 130 can capture a plurality of output signals while the excitation beam 406 scans across the wafer in the X direction to obtain spectral and spatial information.

In another embodiment, the detector 130 can use a photomultiplier tube (PMT) or a astigmatism diode (APD). As shown in FIG. 19, upon exiting the light pipe 412, the optical signal 407 can be filtered by an optical filter 452 and provided to a photomultiplier tube (PMT) or a swell light diode (APD) 462. Optical signal 407 is converted to an electrical signal and recorded by data acquisition device 458, which provides the data to processor 152 for analysis. In this embodiment, spectral information is not obtained, but all wavelengths are integrated into one electrical signal. Accordingly, it may be desirable to synchronize the first source 110 and the second source 140 (FIG. 1) such that the resulting signals are not simultaneously received by the detector 130.

20 is a side view (along the YZ plane). By way of example, the side view shows dark field scattered radiation, photoluminescence, and brightness as seen by the optical metrology device using the elliptical mirror 402 using the light pipe 412. The field is reflected while collecting radiation. As illustrated, illumination beam 114 produces scattered light 115 and excites photoluminescent light 117, which is received by spectrometer 134 along with reflected broadband light 143.

The detector 130, which may include the optical device 132, the spectrometer 134, and the sensor 136, can simultaneously record the photoluminescence light generated in the sample 101 in response to the excitation by the illumination beam 114 and the scattered light from the illumination beam 114, and Depending on the situation, one of the broadband light 143 is bright field reflected (e.g., if the light pipe 412 has one of the signal outputs in the form of a line to provide spatial information). If desired, the detector 130 can further record a dark field scatter of the illumination beam 114 due to a defect on the sample, such that if desired, three separate signals are simultaneously imaged. The detector 130 is used to collect all three signals such that there is no spatial or temporal shift between the three signals. A spectrometer 134 splits the signal into three different spectral information channels, i.e., senses with a 2D sensor array of detectors 130. The signal is spectrally separated (recorded) into different wavelength bins (sensor pixels).

By using the elliptical mirror 402, the optical signals emitted from the surface of the sample 101 are collected by high-NA mirror-based optics that achieve high collection efficiency and high instrument sensitivity of the optical signal. In the X direction, the sample is excited in the form of one of the lines produced by the scanning system 116, which achieves a high rate of measurement. The measurement configuration is supplemented by the application of a light pipe 412 that enables the collection of optical signals from the same length of long lines and the transition of optical signals to a desired shape without mechanical movement (such as a small circular area or In the first line). Applications with multiple fiber optic circuits with thousands of individual fibers achieve high resolutions of up to tens of microns per pixel. Therefore, the device achieves high sensitivity, high resolution, and high speed (measured delivery amount).

Although specific embodiments are provided herein for illustrative purposes, the described embodiments are not limiting. Various adaptations and modifications can be made without departing from the scope of the invention. For example, a rotating stage can be used in place of a linear stage for scanning illumination lines 122 and 142 across the surface of sample 101. Again, scanning system 116 can be modified to eliminate (eg, a fixed mirror), or an F-theta lens can be used to focus illumination beam 114 onto the surface of sample 101. Other modifications and variations are possible, and therefore, the spirit and scope of the appended claims should not be limited to the foregoing description.

Claims (27)

An optical metering device comprising: an illumination source that generates a first beam; a first lens system that causes the first beam to be incident on a surface of the same as one of the orientations along a first direction An illumination line incident on the sample at a first incident angle, wherein the sample emits photoluminescence light along the first illumination line in response to excitation by the first beam; a second illumination source; a second lens system that focuses light emitted by the second illumination source onto the sample as the first illumination line oriented along the first direction and superimposed on the surface of the sample a second illumination line incident on the sample at a second incident angle different from the first incident angle; a stage for providing the sample and the first illumination line and the a second movement of the second illumination line in a second direction different from the first direction; a detector that collects the reflected light from the second illumination line and receives the sample along the first illumination Line emits the photoluminescent light; a letter Collecting optics extending to a length of the first illumination line and the second illumination line, the signal collection optics receiving the photoluminescent light from the first illumination line and the reflection from the second illumination line Light, and focusing the photoluminescent light and the reflected light into a line; a light pipe having a linear receiving end for receiving the photoluminescent light focused by the signal collecting optics and the reflected light, the light pipe Further having a configuration to Photoluminescent light and the reflected light are provided to an output of the detector, the output having a shape different from one of the linear receiving ends; and a processor coupled to the detector and configured to The photoluminescence light and the reflected light are used to determine a characteristic of the sample for a plurality of locations on the surface of the sample. The device of claim 1, wherein the signal collecting optics is one of an elliptical cylindrical mirror or a cylindrical lens. The device of claim 2, wherein the signal collecting optics has a numerical aperture (NA) of 0.4 or greater. The device of claim 1, wherein the light guide comprises a plurality of optical fibers having a first configuration at the linear receiving end and having a second configuration different from the first configuration at the output, and Wherein the output has a shape that matches one of the shape of one of the entrance apertures of the detector. The apparatus of claim 1, wherein a portion of the first light beam is scattered along a surface of the first illumination line from a surface defect on the sample to generate a scatter signal, the detector receiving the scatter signal. The device of claim 5, wherein the processor generates the surface defect image of the sample using the scattered signals received from the detector. The device of claim 1, wherein the first lens system comprises a scanning mirror to make the first light A scan is traversed across the sample in the second direction to form the first illumination line. The device of claim 1, wherein the first illumination line and the second illumination line are simultaneously generated. The device of claim 1, wherein the first illumination line and the second illumination line are sequentially generated. The device of claim 1, wherein the detector comprises a photomultiplier tube (PMT) or a astigmatism diode (APD). The device of claim 1, wherein the second illumination source generates a broadband light source of broadband light and the reflected light reflects broadband light, and wherein the detector reflects the broadband on a two-dimensional array Light and the photoluminescence light image and in response generate an image frame having a first dimension representing spatial information along the second direction and representing the reflected broadband light and the photoluminescence a second dimension of light spectral information, wherein the detector generates the first illumination line and the second illumination for the surface superimposed on the sample when the stage moves the sample along the first direction A plurality of image frames of a plurality of positions of the line. An optical metering device comprising: a light source that generates an illumination beam; an optical system that receives the illumination beam and produces an illumination spot on a surface of a sample; and a scanning system that scans the illumination point across The sample is formed to form an illumination line, wherein the sample emits light along the illumination line in response to excitation caused by the illumination point Light; a stage for providing relative movement between the illumination line and the sample; a signal collection optic extending to a length of the illumination line, the signal collection optics receiving the illumination line The photoluminescent light and focusing the photoluminescent light into a line; a light pipe having a linear receiving end for receiving the photoluminescent light focused by the signal collecting optics, the light pipe further having an output The output has a shape different from one of the linear receiving ends; a detector that collects the photoluminescent light from the light pipe, the detector having a shape matching one of the output ends of the light pipe An inlet aperture; and a processor coupled to the detector to receive the photoluminescent light to determine a characteristic of the sample. The device of claim 12, wherein the signal collection optics is one of an elliptical cylindrical mirror or a cylindrical lens. The device of claim 13, wherein the signal collecting optics has a numerical aperture (NA) of 0.4 or greater. The device of claim 12, wherein the light guide comprises a plurality of optical fibers having a first configuration at the linear receiving end and having a second configuration at the output different from the first configuration. The device of claim 12, wherein a portion of the illumination beam is scattered along the illumination line from a surface defect on the sample to produce a scatter signal, wherein the signal collection optics receives the scatter signal and uses the light pipe to A scatter signal is provided to the detector. The device of claim 12, wherein the scanning system scans the illumination beam in a plane that is at an illegal line incidence angle on the sample. The device of claim 12, wherein the detector comprises a photomultiplier tube (PMT) or a astigmatism diode (APD). The apparatus of claim 12, wherein all of the wavelengths of the illumination beam are simultaneously combined in the illumination spot, and wherein the detector images the photoluminescence light emitted along the illumination line on a two-dimensional array, The two-dimensional array has a first dimension representing one of spatial information along the illumination line and a second dimension representing spectral information of the photoluminescent light, wherein the detector generates the representation of the emission along the illumination line An image frame of photoluminescence light, and wherein the detector generates a plurality of images of the illumination line on the surface of the sample when the stage generates relative movement between the illumination line and the sample Frame. The device of claim 12, wherein the illumination beam is a first illumination beam, the illumination line is a first illumination line, the device further comprising: a broadband light source that produces broadband light; and a lens that will The broadband light is focused on the surface of the sample into a second illumination line, the second illumination line superimposing the first illumination line and being aligned with the first illumination line, and An incident angle different from an incident angle of one of the planes of the illumination beam is incident on the sample, wherein the second illumination line is reflected by the sample to generate reflected light; wherein the signal collecting optics further receives the reflected light and The reflected light is focused into a line, and the light guide receives the reflected light from the signal collecting optics; and wherein the detector collects the reflected light from the light pipe, and wherein the processor further determines the sample using the reflected light One of the features. The device of claim 20, wherein the signal collection optics receives specularly reflected broadband light. The apparatus of claim 12, wherein the scanning system that causes the illumination spot to scan on the surface of the sample to form the illumination line comprises a galvanometer mirror or a polygon mirror. An optical metrology method comprising: illuminating a surface with a light source along an illumination line having one of the directions along a first direction, wherein the sample is responsive to excitation by light from the source The illumination line emits photoluminescent light; a signal collecting optics is used along the length of one of the illumination lines to collect the photoluminescent light from the illumination line and use the signal collection optics to focus the photoluminescent light into a line Receiving the photoluminescent light along the line using a light pipe having a linear receiving end and outputting the photoluminescent light from the light pipe at an output having a shape different from one of the linear receiving ends; Detecting the photoluminescence light received from the output end of the light guide by using one of the inlet apertures having a shape matching one of the output ends of the light guide; making the illumination line different from the One of the first directions moves in a second direction across the surface of the sample; and the photoluminescent light detected by the detector determines a characteristic of the sample for a plurality of locations on the surface of the sample. The method of claim 23, wherein the signal collecting optics is one of an elliptical cylindrical mirror or a cylindrical lens and has a numerical aperture (NA) of 0.4 or greater. The method of claim 23, further comprising transmitting the photoluminescent light using a plurality of optical fibers in the light pipe, wherein the optical fibers have a first configuration at the linear receiving end and are different at the output end The second configuration is one of the first configurations. The method of claim 23, wherein a portion of the illumination beam is scattered along the illumination line from a surface defect on the sample to produce a scatter signal, the method further comprising collecting the scatter signal using the signal collection optics and using the light A conduit provides the scatter signal to the detector. The method of claim 23, wherein the detecting the photoluminescence light is performed by one of a photomultiplier tube (PMT), a astigmatism diode (APD), or a spectrometer.