TW408215B - Method and apparatus for reducing roughness scatter as a noise source in wafer scanning system - Google Patents

Abstract

The present invention provides a method and apparatus for detecting defects on the surface of a workpiece in which the noise contributions from topographic scatter can be reduced. The signal-to-noise ratio is thus increased, increasing the sensitivity of the scanning system and enabling it to detect smaller, such as a wafer. The method involves directing a polarized light beam onto the surface of the workpiece at a non-normal incident angle; collecting light scattered from the surface of the workpiece at a selected location in the scattering hemisphere, the scattered light including a component resulting from defects present on the workpiece surface and a component due to topographic roughness of the workpiece surface; filtering the collected scattered light through a filter oriented to minimize the topographic scatter component in the collected scattered light; and detecting the thus-filtered light.

Description

A figure (Figure 14) represents the superimposed differential scattering cross section (DSC) type. Article detection optical system. Scanner design configuration of the first type without out-of-plane detection and V. Description of the invention (17) BRDF 'derived' and drawn with out-of-face collection and explained (Figure 15) represent the same basic configuration 'but . '° M and detection. The optical system contains the data of various materials of the polarizer shadow test ^ * ^ materials. The position of the detector 128 shown in Figures 7 and 8 has been calculated. It is _51 degrees off-center and includes a polarizer that can separately capture p-polarized light after being guided, which can greatly improve its performance for the test material. Because the depth of immersion in aluminum and silicon is relatively shallow, it may be advantageous to add an aperture stop before the detector to narrow the field of view. Data analysis using measured metal surfaces confirms that the intensity of the particulate signal is two to several times higher than the surface scattering. Similar improvements can also be made for aluminum and polycrystalline silicon substrates. Component symbol hanging photo description '/ 2 0 Surface inspection system 21 Workbench 22 Cover 23 Image display 25 Keyboard 26 Mouse 27 Lower cabinet 28 Lower shelf 29 Printer 29a Printing paper v3 1 Inspection platform

0: \ 56 \ 56506, ptc Page 21, 2000.01. 12.021 408215 V. Description of the invention ¢ 1) The present invention relates to a surface inspection system, more specifically, to a wafer used as a substrate in a microelectronic device Surface inspection. Wafer particle scanners have been in use for many years and are designed to detect and map surface defects on wafers. It uses a laser beam to scan the wafer surface and then records the position and size of the scattered light from the surface. When the laser beam hits a particle or a pit with a large enough size, a scattering intensity higher than the normal background noise signal will be detected. The smallest particles detected with this scanning system are related to these background noise signals. A large source of background noise from surface roughness (or surface undulation) is from the fine coarse chains on the wafer surface. SUMMARY OF THE INVENTION The present invention provides a method and apparatus for reducing noise from surface scattering contributions. The signal-to-noise ratio is improved compared to 焉, which increases the sensitivity of the scanning system and enables detection of even smaller defects. The theory of the present invention is based on a deep understanding of the scattering of light beams from rough surfaces. More specifically, it is a knowledge of how to effectively detect the light beams collected and analyzed on the surface of the wafer. The scattering behavior of the polarized incident light beam is to reduce the collection of scattered light due to surface scattering and maximize the quantization of the scattered light component caused by defects existing on the wafer surface. After measuring the polarization state of the optical signal, its characteristics can be expressed by calculating the four terms (SO, S1, S2, and S3) of the well-known Stokes vector. Familiar technique), you can use these four values to calculate the other four quantities. Three of them define the order after full polarization

408215 V. Description of the invention (2) The polarization state of the colored light beam. They are two chord-like optical electric field amplitudes that are perpendicular to each other with a phase angle. These three quantities can be used to explain the polarization state of the beam after full polarization. The fourth term is calculated when the Stark phasor is partially depolarized. If the light is 100% polarized, it can be removed by placing a filter composed of a quarter wave plate in front of the polarizer. The filter is adjusted by the components of its surface normals by individual rotations. These filtering techniques are well documented in the literature, and the research in this part of the field is specifically named polarized optics. If a 100% polarized light source (such as a laser) is used, the characteristics of the sample determine which reflected light will undergo polarization treatment. In general, the sample scatters the beam multiple times before the light leaves the reflector (such as a piece of paper) and substantially depolarizes the beam. On the other hand, the polarization state of the scattered signal generated by a signal scattering event (such as surface scattering from a flat surface) is also different from that of the incident beam 1 but 100% polarized. Shixi wafers, mirrors, and other reflectors are all optically flat scattering surfaces under these conditions. Some surface features, such as PSL spheres located on the surface of the crystal, will not depolarize the beam: although they will produce different polarization states than those caused by surface scattering. Other surface features, such as deep-penetrating or particulate material properties, are isotropic in terms of their properties and will therefore depolarize the scattered signal. Changes in the polarization signal and the amount of depolarization can help distinguish each other's characteristics. In fact, the surface scattering from a flat surface is still 100% polarized, so it can be eliminated by placing a suitable filter anywhere on the scattering hemisphere. But those scattered by dielectric surfaces (non-metallic) need only be at an appropriate angle 1 ^^ iiain

4Q8215 V. Description of the invention ¢ 3) A polarizer can be easily used to complete the filtering effect; however, no film is required. In the case of metals (or materials with non-zero absorption coefficients), the wave plate must be used to filter the incident phase. Silicon can almost be described as a dielectric surface due to its very small absorption coefficient and excellent filters using only one polarizer. The present invention relates to the use of a light source architecture (for example, a high-angle P transformation), which can naturally generate less surface area t at a specific position of the scattering hemisphere and then pass through the area with a polarizer. Surface scattering caused by optically flat surfaces is a well-known and documented phenomenon. The relationship of normalized scattering intensity is: Ιίϋλ = cos 2 es cos 0,05 (/) ⑴

Pi A4, where PS is the angle of 7Γ watts and the surface normal inflammation θ i angle, and enter the solid angle Ω along the definition method of angle θ s (each represents polar angle and meridian angle). power. This Q quantity is a polarization factor (sometimes a unit Jones (J ο nes) vector) and is used to describe the material characteristics of the substrate S (f) as a spectral density function of the surface power and to explain that the surface fluctuations actually have The four Q quantities may cover two orthogonal polarization states in the light source and the scattering field. The equation representing these four terms is the complex permittivity of the surface as shown below. The use of waves for its wave effect is extremely polarized and scattered. degree. !, This Q, (£ -1) C0S ^ t (cos θί + Js-sin1 9S + ^ [ε-sin’- Θ, —) (2)

408215 V. Description of the invention (4) 2 Qxp " (^ ―1) ^-sin2 θκ sin ^ ¥ (cosOf + ^ 1 ε-sin2 0!) (Cosθχ + ^ je ~ sm2 2 QPs = (s-1) λ / £ ·-sin2 sinΦκ (scosA + taxi- sin2 AXcosA +-sin2 0Λ) 2 Qpp = (s-sin2 9S 4ε-sin2 θ, cosA--sin ^,) (£: cos ^ 4- _ sin2 θ · {) {Ε cos & s-sin (3) (5) Note the equation (1). If Q is zero, the surface scattering will be reduced to zero no matter how rough the surface is. Looking at these four Q quantities, then Reveals that when e. ≫ 1 (constantly true, but except in free space), it will still occur under certain specific conditions. Qsp in the plane of incidence (when 0 = 0 and 180 degrees) And Qps are zero and Qss in the vertical plane (must = 90 and 270 degrees) are also zero. These relationships have been emphasized in previously published literature and are considered to be used in particle scattering to reduce surface scattering. The molecular form of Qpp is different from the other three equations. For any real number ε (referring to a dielectric material), the correct choice of the angle of incidence and the angle of scattering can make the molecule zero. For any complex number £ ( Metal) can make the molecule the minimum value. The present invention covers the use of this special effect to reduce the surface scattering caused especially when scanning semiconductor wafers. First consider special cases, and there is a real value ε. Under this condition there is only one A value of 0 makes the numerator of Q ρ ρ the smallest value. When 0 = 0,

408215 V. Description of the invention (5) This is the Brewster's (B r e w s t e r s) angle (the reflection value of the polarized light source at the incident angle p is zero). In any case, pay attention to equation (5). If the value of 0 is different from zero, then only the 0 s or β i can be corrected to make the numerator zero. This means that there are other positions on the hemisphere, that is, away from the special reflection and not in the plane range of the incident light and at the special reflected beam, and the Qpp at these places is zero. In fact, if the numerator is zero, the 0S value can be solved, and the result is an equation written in 0 s (when βί is a fixed value), which can define a zero p-polarized scattering on the hemisphere. Of straight lines. The time is measured along this line. The surface scattering component contained in the p-polarizer is greatly reduced when passing through a rotary analyzer. In fact, the measurement aperture is limited (extend along both ends of the straight line) Time), and the analyzer is not perfect, so some surface signals are still detected. Taking a hard wafer as an example, the ε number is the penetration number (£ = 4.4 + iO. 07) ', and Qpp is not exactly zero, but the value is very small. The reason why an analyzer is not used is as follows-the polarization state of the scattering signal including particles from different materials varies. In this example, the total surface scattering signal is proportional to the sum of Qps and Qpp. If we evaluate the combination of silicon, it is found to be a minimum value as a function of various angles. When analyzing the silicon wafer using the special type of wafer scanner disclosed in this article, the optimal positions are at about 0 s = 45 degrees and Θ s = 50 degrees. It is known from the previous discussion that the present invention provides a method and device for detecting defects on the surface of a workpiece, such as a wafer. The steps are as follows: a polarized beam is directed to the surface of the workpiece at an illegal angle of incidence; The light beam scattered by the surface of the workpiece is collected at a specific position in the hemisphere, and the scattered light includes a component contributed by a defect existing on the surface of the workpiece and another from the workpiece

Page 9_40.8.215_ V. Description of the invention (6) Surface surface roughness contribution component; use a directional filter to filter the collected scattered light to minimize the surface scattered component of the collected scattered light; Finally, the filtered beam is detected. In another aspect, the present invention provides a method for detecting defects on the surface of a workpiece. The steps are as follows: a P-polarized beam is directed to the surface of the workpiece at an illegal angle of incidence; and the scattering from the surface of the workpiece is collected. The scattered light contains the component contributed by the defect existing on the workpiece surface and another component contributed by the surface roughness of the workpiece surface; and the collection step is within the emitting hemisphere and is not on the plane defined by the incident beam Somewhere, this can minimize the unit chin vector of p ~ polarized incident and P-polarized scattering field; then collect the scattered light through a directional polarizer to scatter the collected scattered light surface The weight is minimized. Brief Description of the Drawings Some of the characteristics and advantages of the present invention have been revealed, but others will be clear from the following detailed description and illustrations, where: Figure 1 is a perspective view of a surface inspection system according to the present invention. Figure 2 shows a wafer inspection table for a surface inspection system according to the present invention, which is intended to rotate and translate a workpiece, such as a wafer, moving along the path of the material. Figure 3 is a side view of the surface inspection system. FIG. 3A is a cross-sectional view of a light path detector in a surface inspection system. FIG. 4 is a side view of the optical scanning system. Figure 5 shows the direction of rotation and translation when the wafer passes through the inspection area.

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Page 10 4〇8215 ---- ^ ________ 5 'Description of the invention ^^' 'Figure 6 is an example side view of the old collector, and the one shown is the position of a discrete light detector that collects scattered light. Figure 7 is a top view of the collector, and the position of the split photodetector is shown. Figure 8 is a perspective view of the collector, and the one shown is the position of the split photodetector and 0. Figure 9-12 shows the different angles Θ relative to the substrate 'such as sand, titanium, Ming, and tungsten Modified polarization coefficient Qpp. Figure 13 shows the actual B R D F data on the surface of the crane. Figure 14 shows the differential 3 scattering cross section (D C S) 'of two different particle sizes detected along the surface D C S and the results obtained using a previously well-known scanner. Fig. 15 is a diagram similar to Fig. 14 ', i.e., a similar scanner, but according to the teachings of the present invention. The detectors are on the plane and have not been subjected to polarization treatment. DETAILED DESCRIPTION_Detailed description of the embodiment. The present invention will be discussed in detail below with the illustration of a specific embodiment shown in the present invention. The present invention may, in any case, be implemented in a variety of different types and is not limited to the specific embodiments illustrated herein; on the contrary,) these illustrated specific embodiments make the present invention more completely cover the field well-known to those skilled in the art range. The same serial numbers in the text represent the same objects. Fig. 1 is a view of a surface inspection system 20 for detecting defects, such as particles or holes on the surface of a workpiece W or an object, such as a silicon wafer. For the sake of clarity, the part of the system 20 is divided by a dashed line. This example shows each of the face detection systems 20

笫 丨 1page

4082U V. Description of the invention (8) kinds of objects. The surface inspection system 20 is suitable for inspecting the surface of the unpatterned wafer W, whether it is coated or not. The system 20 preferably includes a device capable of translating and conveying the workpiece W along the material path P, and a device for moving the workpiece W in relation to the translation conveying device when conveying along the material path P, and scanning while rotating along the material path P And the surface S of the workpiece W in translation, and a device for collecting reflected and scattered light from the surface S of the workpiece ff. As shown in Fig. 1, the surface inspection system 20 is a workstation configured with a workbench 21. Located on the work table 21 is a substantially closed and completely light school front cover 22, an image display 23, a keyboard 25, and a mouse 26. The lower cabinet 2 7 is suspended under the worktable to support the body system controller 50. Adjacent to the lower cabinet 27 is a printer 29 and the upper printing paper 2 9a under the shelf 28. The outer cover 22 has been partially removed to exemplify the detection configuration of the present invention. The inspection of the wafer W is preferably performed in the inspection zone Z on the inspection table 3I. The automatic wafer transfer arm 3 2 is adjacent to the inspection station 20 so as to load the wafer W wafer box 33 to carry out the inspection station 31. The wafer cassette 33 carries a large number of wafers W and passes through a gate (not shown) and is introduced into the wafer cabinet 27. The conveyance of the wafer W in the cover 2 2 is automatically controlled without touching by hand to avoid contamination or stains. As shown in FIGS. 1 to 3, the surface inspection system 20 preferably includes a device capable of translating and conveying the workpiece W along the material path P. The device for conveying the workpiece W is the illustrated conveyor 40, which is designed to transfer the workpiece W in translation along the material path P, and preferably has a detection belt or zone Z 13 to translate the conveyor 40. As shown in the figure, it preferably contains A gear 42, a motor 41 including a rotating shaft 41 a to rotate the gear 42, and guide plates 36, 37 having a fixed pitch. The motor 41 and the gear 42 are fitted at both ends of the motor shaft 4 1 a to form a chuck of the system 50. Chuck motor

Page 12 408215

4 1 Take a good connection with the wafer holder 4 3, where the wafer holder has a lot of upward extensions for receiving ㈤

The team fixes objects, such as the flange of a silicon wafer, that is, those around the edge of the workpiece. The joining technology of the workpiece can reduce contamination or may be placed under the work. ^ 4 Surface problems caused by close contact with the upper surface of the wafer holder 43. The wafer holder 43 is preferably capable of translating and transmitting along the wafer holder directional plates 38, 39 disposed below it. Other translation and / or rotation devices, such as pistons and cylinder assemblies and motors arranged on wafer holders are intended to rotate the sa ® holders, which can also be implemented by those skilled in the art in accordance with the present invention. 〇Further, a device for rotating the workpiece W. For example, the rotary table 45 cooperates with the conveyor 40 to rotate the workpiece W during the translational movement along the material path P = the rotary table 4 5 As an example, it is better to include a rotary table Ma Yuan 46 at the bottom of the stage allows the wafers above it to rotate at a constant speed. The conveyor 40 and the rotary table 4 5 are preferably operated synchronously and cooperate with the scanner 80 to scan the entire wafer at a small spiral angle (α) during rotation and horizontal movement along the material path P. . As shown in Figures 1 and 3-5, the scanner 80 is configured to scan the surface of the workpiece W during rotation and translational movement along the material path P. It should also be understood ’that for those skilled in the art, the scanner 80 can also rotate and / or translate when the workpiece is stationary or in translation or rotation. In addition, other material paths are also possible. For example, the workpiece W and the scanner 80 cannot perform the same translational movement and the workpiece can only be detected in a single rotation path. Accordingly, the present invention includes a p-polarized light source 81 or a light source equipped with a P-polarized filter aligned with the light source to emit a P-polarized light.

Page 13 〇8Sls V. Description of the invention (10) The beam B, which receives the light source and the surface of the scanned object, that is, a mirror 82, lenses 84, 86, and also rotates individually to scan in parallel. # 扣 5 ， And the installation of the object rotating table 45 DU, that is, the transmitter 40 and the scanner 80 preferably contain a light source 81, @, 一 ,, linear polarization or P-polarization, tapping R to generate a force of 0 The wave crossing device is closed. Bu polar pole: p-of the light source calibration is biased at half of the maximum value of 0 ″. It is best to cover the full width of the small device with two parts. When the workpiece is connected along the material = two / solid, the beam 3 moves with a relatively narrow scanning path (f-diameter P and slave rotation and translation). Transport beam. The light source 81 is preferably a wavelength phase (when 2 traces detect the surface S of the workpiece W, or the solid state, both are skilled in the art I see the photoluminescence, such as argon ion external optics combination; also: : = 丄 Laser 81 is also best with a diameter of light about 0.6 cm d!) ;. Clouds are known by the heat. The device of laser 81 is best to include a zigzag cry, ft after Then, the light beam B is deflected to a relatively narrow one; 乂, as in the example *, the receiving light beam 6 is exemplified as an acousto-optic refraction ^ insertion path (α). The narrowest scanning path of the refractor 85 (㈧ is preferably not wide-resonance scanning 11, and this is equivalent, that is, between om ~. '. 4., ΓΛ; "radians, and the most detailed way is the path p direction of the path —Σ: Inside. The scanning path "is best parallel to the finger. Folding two is shown in Figure 4, and it is best done as a vector. For example #, this way :: It is south frequency * The wave excites the crystal to change the angle of the forward wave. The light waves interact with each other. The light beam is deflected after the light penetrates, and the crystal is excited at the same frequency with the same frequency. If the acoustic frequency is changed to a saw,

Brother page 14 _215 V. Description of the invention (11) Tooth waveform, then the angle (α) of sweeping the finger to the .. ^ optical device 85 preferably fixes the beam β is proportional to the frequency. A0 fold particles or defects; ΐ ::, 'If r can respond to the surface of the inspection object and A0 refractor 1 ^ a predetermined t time? Although the invention and the invention adopt other belts, even those skilled in the art can also use this piezoelectric scanner ... = small-angle scan # 'examples, galvanometer, other electronic sweep ; Wait for the reflector, the scanning head, the laser beam i, and the square: Π2; well placed in the 0 :: beam β put Ϊ description of the working aperture of ^ Ϊ Ϊ ^ 彻底 to completely and efficiently carry the scan with the refractor 85 The device 80 also preferably includes a device that is calibrated with the refractor 85. Fang Xinggong: W two material paths p line rotation or translation motion is relatively high: within 1 (from the normal vector of the workpiece) will come from a narrow scan The path (^) light beam is directed to the surface s of the workpiece W. Although a high incidence angle (Sichuan is better, the angle of incidence at any angle perpendicular to the workpiece W can exhibit the advantages of the present invention. The angle of incidence from the normal of the surface of the object is preferably greater than "degrees, which means that The surface of the workpiece is less than 45 degrees, but in more detail, the normal direction of the surface of the object is preferably in the range of 65 to 85 degrees. The guide device, for example, has a reflector 82 and a number of optical lenses 84, 86, which aims to guide the light beam β from the laser 81 to the surface S of the workpiece ψ to be inspected. After the light beam B passes through the A0 refractor 85, the light beam β passes through the cylindrical lens 84, which has an ideal angle correction effect and then the light beam ^ Used to perform a linear scan on the surface of an object that is being translated and rotated by the detection belt.

Page 15 408215 5. Description of the invention (12) The alignment of the optical device 87 and the cylindrical lens 84 adjacent to the A0 refractor 85 can block a relatively small part of the light beam scanning the surface of the workpiece W without linear turning. The optical lens 86 behind the cylindrical lens 84 is a focusing or f-Θ lens. Anyone skilled in the art understands that the light beam is intended to irradiate the surface of the workpiece W at a focal length. The scanner 80 according to the present invention is preferably capable of operating in a rotating and linear, lateral, or translation manner (Y) to scan the light beam B in a radial direction to perform a spiral scanning pattern as shown in FIG. 3. However, any other material path P can be adopted for the workpiece w to exhibit the advantages of the present invention. 0 As shown in Figures 1 '3' 3A and 6-7, it is best to collect the light beam from the surface of the workpiece with a bright channel detector 1 1 〇 collector 1 〇 00 to detect the special The light beam reflected on the surface S of W, and the dark channel detector 120 next to the bright channel detector can detect the scattered light from the surface s of the workpiece w. The bright channel detector 1 10 may be a PMT or a photodiode, but it is better; anyone skilled in the art understands that it is a tetrode element, that is, the detector 1 is designed to do X-Y coordinate positioning. So The deviation of the reflected light path is determined during the detection of defects or particles. This quadrupole detector is manufactured by Advanced Photon i, Inc., the predecessor of Silicon Detector Corp. of Camarillo, California. Although a particular configuration mode has been exemplified, it should be understood that various other configurations of rectangular or multi-pole, i.e., bipolar, etc., can also be adopted according to the present invention. The dark channel detector 1 2 0 preferably contains a plurality of collectors 1 2 1, 123, 125 ′ 127 ′ next to each other, which aim to collect scattered light components of different predetermined angles from the surface 3 of the workpiece w. There are at least two of the multiple optical collectors formed by the dark channel detector 1 2 0 121 ’123’ 125 ’127.

Page 16 408215 V. Description of the invention (13) This adjacent collector. Many collectors exemplified 1 2 1, 1 2 3, 1 2 5 and 12 are known to those skilled in the art = the compound lens according to the present invention, and other lens configurations can also be adopted. One of the collectors 121 is a front channel collector. It is located in the plane of the forward incident beam, where the beam scanning wafer ff aims to collect the scattered light component before the surface S from the workpiece W is collected at a relatively small angle 6a. The centered channel collector 123 is located next to the forward channel collector 121 and is located in the plane of the incident beam, and is intended to collect the near-normal scattered light components collected from the surface S of the workpiece W at a relatively moderate angle 0b. Back channel

The collector 125 is immediately adjacent to the centering channel collector 123 but not in the plane of the incident beam, and is intended to collect the back scattered light components collected from the surface S of the workpiece w at a considerable angle 6c. Another off-axis collector 1 2 7 is located at a polar angle of 0 s and a meridian angle of 0 s, which is used here to reduce the scattered light component from the surface scattering. The dark channel detector 1 2 0 further includes a forward channel detector 1 22, a center channel detector 1 24, a backward channel detector 1 26, and an off-axis channel detector 1 2 8 Each of the detectors and the corresponding collectors 1 2 1, I 2 3, 1 2 5, 1, 1 7 maintain optical communication status. A polarized wave crossing device 1 2 9 is located before the off-axis channel detector 1 2 8. The filters 1 2 9 can minimize the scattered light on the surface of the thick chain after being guided. In the preferred embodiment, the p-component of the scattered light 127 is zero, and the polarization filter 299 is passed backward to cancel the S-polarized light beam scattered from the surface. The signals obtained from the respective detection standards 122 '124' 126 and 128 are guided to the electronic signal identification circuit 150. As shown in FIGS. 1 ′ 3 and 6, the relative angles between the collectors 1 2 1, 1 2 3, and 1 2 5 are θ a, θ b, and θ c are preferably relative to the surface of the piece W.

408215 V. Description of the invention (u) The reflection angle of the beam of S and its relative forward and backward directions, as well as the near-normal scattered light components related to the scanning incident angle 0 i can be obtained. For example, if the angle of incidence < 9 i is quite high, for example, calculated as -7 5 ° from the normal (15 ° from the level), the forward scattering or small angle β a is preferably about + 2 2 ° to + 67 °, the near normal scattering or middle angle 0b is between about -25 ° to + 20 °, and the backscattering or large angle θc is between about -72 ^ to -27 °.

The dark channel collector 120 and the related signal recognition circuit 150 according to the present invention can successfully analyze the characteristics of the surface S and particle scattering, such as applied to polished wafers and different deposited films. Under certain conditions, that is, after the tolerance of the most important surface roughness is reached, the distribution of scattered light from the surface (BRDF) can be expressed as: BRDF = [16π2 cos Q; cos 0S Q 3 (^, ίν)] / λ4 where 0C is the angle of incidence, the angle of scattering, Q is the reflectance at a certain wavelength and the incident light is polarized (or polarized by this coefficient, S is the power spectral characteristic of surface roughness' λ is the incident light Wavelength 5 is the spatial frequency. Finally, the table of incidence and scattering angles can be expressed as follows: fx = (sin θ $ cos φ3-sin Q {)! Λ fy = sin 0s sin <} > s / λ. In the equation, 0 constant represents the incident angle of plane and 0 is the meridian angle (not on the plane). The line shape of the B RDF curve is defined by S (f χ 1 fy) and the cosine term of the above equation. The ideal result obtained can be obtained from Outstanding power light

Page 18 408215. V. Description of the Invention The large curve of the object on the surface of the object ^ h mainly depends on the reflectance Q. It is related to the dielectric constant of the material or the measured particles, and the particles or defects detected on the surface thereof, and according to the present invention, such as silicon and aluminum. And the reflectivity is better, and # the microbe obtained by illuminating the material or the microbeads obtained by irradiating the material. P polarization is not the same as irradiating the material with S polarization or (Brewster's angi) ^ at a specific angle, that is, Brewster's angle is the refractive index (, the reflectivity obtained by the electric mass is zero, and i Function:% = tan ~ ln For example, metal and other absorptions. Same; however, P-polarized day "materials" show the average linear value of the curve. The non-zero minimum ^ and the reflectance obtained are non- The minimum of zero or another name is the principal angle (the angle of pri is called pseudo (Pseudo) at Rust's angle (n'ig bb ^ 1P & 1). The principal angle is related to the complex permittivity 丄 K) and can be rooted. 6 — The following formula of the Chinese demon estimates: Iterative basis is (n2 + k2) 1/2: sin20p / c〇s θ0 For example 'Although the name is different from Shi Xi, but ifr m · * · i' Lu Weiqiang has a strong absorptive mass and silicon mediate rune, so his main body y ^ η ^ is 78 τ. The main angle of the two is almost the same, which is about 78. (For example, 5 8.8 'oxidation The refractive index of silicon is about 1,65 and the principal angle is equivalent to about Kizaki. The characteristics of the dielectric film are also related to the substrate and film thickness, and the reflectance curve. May exhibit minima at different angles of reflection less than Han Xi and stone, and therefore of their lead; ^ Branch of other materials have a refractive index - I Yau to find in monthly or less than about 78.

Ϊ6 ·.

Page 19 V. Description of the invention (16) The BRDF curve can be used to obtain representative data of these different values, the refractive index, and the dielectric constant can be used to obtain the identification information of the particles or defects required by the surface inspection system 50. . The scattering angle obtained from the ratio of the signal to the noise can be obtained by dividing the response of the particles by the root mean square value of B R D F. What is proposed in this way is the equivalent signal-to-noise ratio within a certain limit, and the limit is to know the main source of noise is the "Pong Song perturbation" of the signal for the proficient in the technology. The comparison result of the angles obtained by the dark channel collector 120 collecting the light beam, that is, the scattered light is compared with the existing characteristic data, such as a data table, and the result can be used to identify the defect type. These comparison steps are preferably performed in accordance with established command signals, i.e., software programs that reside on structural hardware or disks or in a manner well known to those skilled in the art. Through measurement and modeling industry confirmation, there is a specific combination mode between input polarization, detector polarization, and optical geometry, so that the intensity of scattered light contributed by surface roughness is almost invisible . In more detail, this includes the proper characterization of the off-axis collector 1 2 8 and the orientation of its polarization filter 1 2 9. The ideal position of the collector 1 2 8 can be obtained by plotting θ p p, and the polarization factor can be obtained from the above equation (5). Figures 7 and 8 illustrate the shapes and positions of the collectors 1 2 2, 1 2 4, 1 2 5 and 1 2 7 of the scanning device described herein. In Figures 9 to 12, θ pp of many important materials are plotted, namely silicon, titanium, aluminum, and tungsten. This particular illustrated shape passes through another plane that is 45 degrees from the incident surface. In order to analyze the detection efficiency on the real crane surface, BRDF was measured according to industry standards. POLAR output uses two different PSL sphere sizes (130 nm and 39.8 nm) along the surface D S C (measured by

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A figure (Figure 14) represents the superimposed differential scattering cross section (DSC) type. Article detection optical system. Scanner design configuration of the first type without out-of-plane detection and V. Description of the invention (17) BRDF 'derived' and drawn with out-of-face collection and explained (Figure 15) represent the same basic configuration 'but . '° M and detection. The optical system contains the data of various materials of the polarizer shadow test ^ * ^ materials. The position of the detector 128 shown in Figures 7 and 8 has been calculated. It is _51 degrees off-center and includes a polarizer that can separately capture p-polarized light after being guided, which can greatly improve its performance for the test material. Because the depth of immersion in aluminum and silicon is relatively shallow, it may be advantageous to add an aperture stop before the detector to narrow the field of view. Data analysis using measured metal surfaces confirms that the intensity of the particulate signal is two to several times higher than the surface scattering. Similar improvements can also be made for aluminum and polycrystalline silicon substrates. Component symbol hanging photo description '/ 2 0 Surface inspection system 21 Workbench 22 Cover 23 Image display 25 Keyboard 26 Mouse 27 Lower cabinet 28 Lower shelf 29 Printer 29a Printing paper v3 1 Inspection platform

0: \ 56 \ 56506, ptc Page 21, 2001.01. 12.021 Correction _ minus 8 Li Shi 1439 _ month 5, invention description (173 32 'automatic wafer transfer arm 3 3 crystal box 36' 37 guide plate 38 '39 crystal Round base guide plate 40 Conveyor 41 Motor 4 1 a Rotary shaft 42 Gear 43 Wafer base 43a Flange 4 5 Rotary table 4 6 Motor-50 System controller 80 Scanner 81 Light source 82 Reflector 84, 86 Lens 8 5: Refraction 8 7 Positive light 1 0 0 Collector 1 1 0 Bright channel detector 1 2 0 Dark channel detector 122 Forward channel detector 121 '123 > 125' 127 Collector 1 2 4 Middle channel detection Device

O: \ 56 \ 56506.ptc Page 21a 2000.01.12.022 _ Case No. 87ί21439 _ Year, month, and day five. Description of the invention (l? T) 1 2 6 Backward channel detector 128 Off-axis channel detector 1 2 9 Polarization filter 1 5 0 Electronic signal identification circuit BP Polarized beam P Material path S Surface W Workpiece Y Linear, lateral, or translational mode Z Detection area

O: \ 56 \ 56506.ptc Page 21b 2000.01. 12. 023

Claims (1)

8Π2143S 4Ό8215 6. Scope of Patent Application 1. A method for detecting defects on the surface of a workpiece, the method includes the following steps: directing a polarized beam onto the surface of the workpiece along an illegal incidence angle; at a specific position of the scattering hemisphere Collect scattered light from the surface of the workpiece. The scattered light contains the component contributed by the defect existing on the workpiece surface and another component contributed by the surface roughness of the workpiece surface; the scattered light collected by the guided filtering of the guided filter Light to minimize surface scattering components in the scattered light collected and collected; and to detect the filtered light beam. 2. The method according to item 1 of the scope of patent application, wherein the execution method of collecting scattered light is to select a position in the scattering hemisphere that does not fall in the plane defined by the incident beam so that one of the polarization factors in the scattering field Minimized. 3. The method according to item 2 of the scope of patent application, wherein the polarized light beam guided to the plane of the workpiece is a P-polarized light beam, and the position where the scattered light is collected is selected so that the P-polarized light is incident and P-polarized scattering field. The value of the polarizing factor is reduced to a minimum of D. 4. According to the method in the scope of patent application No. 3, the filtering step includes the scattered light collected by the polarizing filter to guide the scattered light. Reduce the surface scattering components in the collected \ scattered light. 5. The method according to any one of claims 1 to 4, wherein the filtering step includes filtering the scattered light collected through a polarizer and a wave plate, and each of them is oriented to enable the scattered light collected. The surface scattering component is minimized. Page 22 408215 6. Application scope 6. —A method for detecting defects on the surface of the workpiece, the method includes the following steps: a P-polarized beam is guided to the surface of the workpiece along an illegal incident angle Θ i; collection Scattered light from the surface of the workpiece. The scattered light includes the component contributed by the defects existing on the surface of the workpiece and another component contributed by the surface roughness of the workpiece surface. The collection method is selected in the scattering hemisphere. One does not fall on the plane defined by the incident beam and is completed with 0s and the position represented by S. The selected angles 0S and 0S can reduce the value of 61 ρρ in the equation to a minimum: _ _. 7 〇l) (^ jε-sin2 ΘΛ. sin.2 cos φχ-εsinθι sin 0V) and (^ cos ^ ,. +-sin2 θ ·) (εcosθχ + ″ ε-sin2 Θχ) are guided by a polarizer to filter the collected scattered light to The surface scattering component of the collected scattered light is minimized. 7. —A device for detecting defects on the surface of a workpiece, comprising: a light source is guided to guide a polarized beam onto the surface of the workpiece at an illegal angle of incidence; a light collector is located in the scattering hemisphere The specific position is to collect the scattered light from the surface of the workpiece. The scattered light includes the component contributed by the defects existing on the surface of the workpiece and another component contributed by the surface roughness of the workpiece surface; a. The positioned filter is used to receive And filter the collected scattered light 1 Page 23 408215 6. Scope of patent application The oriented filter can minimize the surface scattering component of the collected scattered light; and a detector is used to detect the filtered light beam. 8. The device according to item 7 of the scope of the patent application, wherein the collector of scattered light selects a position in the scattering hemisphere that does not fall in a plane defined by the incident beam to reduce one of the polarization factors in the scattering field. To the smallest. 9. The device according to item 8 of the scope of patent application, wherein the light source generates a p-polarized beam, and the position where the scattered light is collected is selected such that the P-polarized incidence and the polarization factor of the P-polarized scattering field The value is reduced to a minimum of 010. The device according to item 9 of the patent application scope, wherein the filter includes a guided polarizer to minimize the surface scattering component of the collected scattered light. 11. The device according to item 7 of the scope of the patent application, wherein the filter includes a polarizer and a wave moon, each of which can be adjusted to minimize the surface scattering component of the collected scattered light. 1 2 The device according to item 7 of the scope of patent application, wherein the light source directs the P-polarized light beam onto the surface of the workpiece along the illegal angle β i; and wherein the light collector is selected in the scattering hemisphere without falling. Completed on the plane defined by the incident light and represented by 0s and 0S, the Θ s and 0 s are selected to minimize the 0 pp value in the equation: 2 _ (g-\) φ-; and ^ PP ycose + γ-Sin2 0,) (£ C〇S0,. + Page 24 408215 6. Scope of patent application A polarization filter is used to collect scattered light. The polarization filter can be guided to minimize the surface scattering component of the collected scattered light. 〇 Page 25