WO1997028422A1

WO1997028422A1 - Foreign matter detector/analyzer and method thereof

Info

Publication number: WO1997028422A1
Application number: PCT/JP1997/000244
Authority: WO
Inventors: Eiji Kanou; Takashi Kido; Yasuhiro Maeda; Kouji Honma; Masayoshi Tsuchiya
Original assignee: Advantest Corporation
Priority date: 1996-01-31
Filing date: 1997-01-31
Publication date: 1997-08-07
Also published as: KR19980703403A; DE19780186T1

Abstract

A laser beam from a projector (51) having a beam spot of 1,000 x 40 νm scans a wafer (12), and the positions of foreign matter is detected and stored by a scatter detector (35). When a portion near this stored position is scanned by a laser beam having a beam spot of 10 νm from a projector (52) and any foreign matter is detected, the range of the beam spot is scanned by a pitch of 1 νm. The position at which the output from the scatter detector becomes maximal is defined as the position of a foreign matter. A range of 1 x 1 νm having the center thereof at the defined position is scanned by an electron beam of 0.1 νm, and the resulting X-rays are detected and the composition is analyzed. The electron beam and the laser beam are arranged in such a manner as to radiate the same point while the wafer (12) is fixed.

Description

Description Foreign matter detection / analysis device and method

Technical field

The present invention detects, for example, a semiconductor wafer on which a semiconductor integrated circuit is formed, a semiconductor wafer during the formation of the semiconductor integrated circuit, and a minute foreign matter attached to the surface of another object, and analyzes the shape, components, and the like of the foreign matter. The present invention relates to a folding device and a method thereof. With the recent increase in the degree of integration of semiconductor integrated circuits, it is indispensable to increase the performance of their production technologies and increase their reliability. Foreign matter may adhere to the circuit wafer surface. There is a close relationship between the amount of foreign matter deposited during manufacturing, whether the manufacturing line is operating stably, and the product yield. In order to reduce the amount of foreign matter attached during manufacturing, it is necessary to detect foreign matter during manufacturing, and to identify the foreign matter by analyzing the components, shape, and other characteristics of the detected foreign matter. However, the conventional foreign matter in-line measuring device is merely a particle counter that counts the number of foreign matter that does not have a function of analyzing the composition of the foreign matter, or can measure the composition of the foreign matter. However, the analysis time was long, the analysis was not automated, and furthermore, the position information needed by a particle counter was required, making it a measurement device that was not practical for inline use. Hereinafter, a conventional apparatus for analyzing foreign matter adhering to the surface of an object will be described with reference to FIG.

The XY stage 11 is mounted on the base 10, and the XY stage 11 is moved on the base 10 in the X-axis movable section 1 1 X and the X-axis movable section 1 1 X. A Y-axis movable section 1 1 y is movably movable in the Y-axis direction, and an inspection object 12 such as a semiconductor device is mounted on the XY stage 11. The driving means for moving the XY stage 11 is not shown in the figure, but the position on the X axis of the XY stage 11 is detected by the X stage generator 13 X, and the position on the Y axis is the Y stage encoder 13 y Is detected by A foreign matter inspection device 14 and an electronic analysis device 15 are arranged in the X-axis direction and located above the XY stage 11 within the movement range of the XY stage 11. The electronic analyzer 15 irradiates the inspection object 12 with an electron beam from the electron gun 16, and secondary electrons generated at that time are emitted. Is detected by the secondary electron detector 17, and or X-ray energy generated by the irradiation of the electron beam is separated by the energy dispersive X-ray diffraction device 18.

Here, it is assumed that all of the devices constituting the foreign substance analyzer are housed in a vacuum vessel (not shown). The foreign substance detection, observation and analysis operations of this foreign substance separating apparatus are performed as follows. Hereinafter, the case where the inspection object 12 is a semiconductor wafer is simply referred to as a wafer 12.

First, the XY stage 11 is driven and controlled in the X and Y directions by a drive control device (not shown) to be disposed below the foreign matter inspection device 14. The foreign matter inspection device 14 irradiates, for example, a laser beam and detects the scattered light.

A laser beam is radiated from the foreign object inspection device 14 to the surface of the substrate 12 while finely moving 11 in the X and Y directions, and the scattered light caused by the minute foreign particles adhering to the surface is observed by the laser light detector. Detect foreign matter adhering to the surface. When the XY stage 11 is stopped when foreign matter on the surface of the wafer 12 is detected, the readings of the X stage generator 13 X and the Y stage encoder 13 y at this time indicate the surface position where the foreign matter has adhered.

Next, when the position of the surface to which the foreign matter adheres is detected by the foreign matter inspection device 14, the XY stage 11 is again driven and controlled in the XY directions, and is disposed below the electronic analyzer 15. Then, the XY stage 11 is finely moved in the XY direction while referring to the surface position of the foreign matter detected earlier, so that the foreign matter attached to the focal point of the electron beam lens of the electron gun 16 coincides with the XY stage 1. Position 1 As a result, the foreign matter to be observed falls within the field of view of the secondary electron detector 17. Here, the external shape can be observed from the secondary electron image of the foreign matter generated by the electron beam irradiated by the electron gun 16. Similarly, X-rays generated by electron beam irradiation can be analyzed by the X-ray spectrometer 18 to analyze the composition of the foreign matter.

Here, by replacing the X-stage encoder 13 X and the Y-stage encoder 13 y with a laser tachometer, the position detection accuracy of the XY stage 11 is improved and the XY stage 11 is moved to the field of view of the electronic analyzer 15. Analytical methods have also been developed to reduce the time required for position reproduction, which is required for the analysis (for details, see JP-A-6-38009). Further, in FIG. 6 of Japanese Patent Application Laid-Open No. 60-218845, a wafer 12 is mounted on a movable stage 21 as shown in FIG. The rotation angle position is detected by the encoder 23, and the movable portion 11X of the encoder 23 is moved in the X-axis direction by rotating the screw 24 by the motor 23X. An electronic diffraction device 15 is located above the stage 21 and a laser beam is applied to a point where the electron beam irradiates the wafer 12. In other words, the laser beam from the laser source 25 is reflected by the reflecting mirror via the optical system 26 and is applied to the wafer 12. The optical system 26 is driven by the motor 27 to rotate the screw 2. 8 is rotated and moved in the horizontal direction, so that the irradiation point of the laser beam can be made coincident with or shifted from the irradiation point of the electron beam. Stage 21 is not an XY stage but an XS stage.

In this conventional technique, the stage 21 is moved in the X direction and rotated, thereby scanning the wafer 12. First, the laser beam is irradiated on the wafer 12, and the scattered light is detected. The position of the foreign matter is detected by the detector 29, and then the optical system 26 is moved so that the electron beam is irradiated to the position where the foreign matter was detected first without disturbing the irradiation of the electron beam. Then, the SEM image at that position is detected. That is, the electron beam is scanned in a plane to detect the SEM image. In this case, it was not possible to detect the true foreign matter detection position composition, etc., instead of the SEM image. In other words, since the resolution of a laser beam cannot be higher than the resolution determined by its wavelength, it has not been possible to improve the resolution beyond about 10 / m at present. On the other hand, an electron beam can have a thickness of about 0.1 m, for example, and can significantly increase the resolution compared to abnormal detection by a laser beam. The composition of the detected abnormal deposit could not be known.

Further, in the apparatus shown in FIG. 2, since the entire optical system 26 is moved, the configuration becomes large and it is difficult to obtain high accuracy.

Further, conventionally, foreign matter detection using a laser beam, for example, uses a laser beam having a spot size of 10 μm in diameter to scan the entire surface on the surface 12. It took.

Moreover, the spot size of the laser beam depends on its wavelength, for example, a diameter of 1 In principle, it was not possible to reduce it below 0 ί / m. Therefore, the resolution of foreign object detection was only 10 μm at most.

On the other hand, the electron beam can be made extremely thin with a diameter of about 0.1 m, and therefore, it is possible to analyze foreign components and the like on the wafer 12 with a positional resolution of 0.1 m. Therefore, in order to analyze the foreign material component with a positional accuracy of 0.1 m, an electron beam with a spot size of 0.1 m can be obtained by measuring a 10 mx 10 m square or a 10 m circle of the optically detected foreign material position. Since it is necessary to perform detection analysis by scanning at, the detection scan took time.

An object of the present invention is to provide an apparatus and a method for detecting foreign matter at high speed. Another object of the invention is the provide a device and method for detecting foreign matter with high positional accuracy ₀

Still another object of the present invention is to provide an apparatus and a method for detecting and analyzing foreign matter at high speed and with high accuracy.

Disclosure of the invention

According to the present invention, the object to be inspected is roughly scanned with a laser beam having a large spot size, a rough foreign matter position is detected, and the range of the large foreign matter position, which is the rough foreign matter position, is set to 10%. Approximately 200 times smaller spot size laser beam is used for coarse particle scanning to detect foreign matter position. This significantly speeds up foreign object detection compared to scanning with only a small spot size.

According to another aspect of the present invention, when a foreign object position is detected by scanning with a laser beam having a small spot size, the position, that is, the range of the spot size of the laser beam is adjusted to a pitch smaller than the spot size, that is, the target accuracy. Scanning is performed at the appropriate pitch, and at that time, the position where the laser scattered light based on the foreign matter is maximized is determined. Foreign object position can be detected.

When analyzing foreign matter using an electron beam, the position of the detected foreign matter may be scanned in the range of the resolution, and the time required for the separation can be significantly reduced. Therefore, a scanning pitch of the laser beam that is smaller than the spot size may be selected according to the scanning range of the electron beam for analysis. Further, in the case of performing analysis using an electron beam, it is preferable that the irradiation point of the laser beam to the test object and the irradiation point of the electron beam be set in advance while the test object is fixed. As soon as a foreign object is detected, the analysis can be performed immediately, and the alignment time and accuracy are not required, and high-speed and high-accuracy analysis can be performed. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a view schematically showing a conventional foreign matter detection / fractionation apparatus.

FIG. 2 is a side view showing another conventional foreign matter detecting and separating apparatus.

FIG. 3A is a plan view showing an embodiment of the present invention.

FIG. 3B is a front view of FIG. 3A.

FIG. 4 shows the relationship between the laser detector 34, the scattered light detector 35, the X-ray diffractometer 37, the secondary electron detector 17 and the supporting plate for supporting the same in the embodiment of FIG. It is a top view.

FIG. 5 is a cross-sectional view of the laser projector 34 in FIG.

FIG. 6 is a sectional view of the scattered light detector 35 in FIG.

FIG. 7 is a cross-sectional view of the X-ray diffractometer 37 in FIG.

FIG. 8 is a sectional view of the backscattered electron detector 36 in FIG.

FIG. 9 is a flowchart showing the operation procedure of the embodiment of the present invention.

FIG. 10 is a diagram showing another example of a switching portion between a laser beam and an electron beam. FIG. 11 is a diagram schematically showing another embodiment of the present invention.

FIG. 12 is a diagram showing an outline of still another embodiment.

FIG. 13 is a diagram showing an outline of still another embodiment.

FIG. 14 is a diagram showing an example in which the incident angles of the two laser beams are different. FIG. 15 is a diagram showing a state of a position detection error due to the laser beam due to the convex portion of the inspection object in FIG.

FIG. 16 is a diagram showing an example in which a laser source is built in an electron gun.

FIG. 17 is a diagram showing another example.

FIG. 18 is a diagram showing still another example.

Any of the above foreign substance separation apparatuses can detect foreign substances adhering to an object and observe and analyze the external shape of the detected foreign substance. It was not possible to perform in-line observation and analysis operations of the work and external shape, and it took a long time to perform all the operations, and the operations themselves were complicated and difficult. Best form to do

FIG. 3 shows an embodiment of the present invention. The inside of the vacuum vessel 30 is indicated by a dotted line. In the vacuum container 30, a movable stage 32 such as an XY stage or an X0 stage is provided on a base 31, and an object to be inspected, for example, 1 2 will be mounted. The movable stage 32 is an XY stage in this example, and is provided with an X stage encoder 13x and a Y stagegen coder 13y. Foreign substance inspection device consisting of laser projector 34 and laser diffusion detector 35 and electron gun consisting of electron gun 16, secondary electron detector 17, reflected electron detector 36, X-ray analyzer 37 A device 15 is provided. A plurality of columns 38 are erected on the base 31 in the vacuum vessel 30, and a support plate 39 is horizontally supported on these columns 38. The support plate 39 supports the electron gun 16, secondary electron detector 17, backscattered electron detector 36, X-ray analyzer 37, laser detector 34, laser scattered light detector 35, etc. I have. The inside of the electron gun 16 is evacuated through the exhaust part 30a.

Fig. 4 shows the arrangement of the support plate 39 and the secondary electron detector 17, the backscattered electron detector 36, the laser projector 34, and the laser scattered light detector 35 supported by the support plate 39. Support plate

A central hole 4 1 is formed in the center of 3 9, and a radial cutout 4 2,

4 3 is formed, notch 4 2 laser scattering light detector 3 5 force notch 4 3 X-ray detector 3 7 force, notch 4 4 secondary electron detector 17 is located I have. Further, a laser beam detector 34 is located in a notch 45 extending from the center hole 41 to the outer periphery 支持 of the support plate 39, and a backscattered electron detector 36 is located in a radial hole 46 relative to the center hole 41. Is located. In FIG. 2, the electron gun 16 is omitted.

In the present invention, the point 50 at which the electron beam of the electron gun 16 irradiates the wafer 12 coincides with the point at which the laser beam from the laser projector 34 irradiates the wafer 12. Further, in this embodiment, as shown in FIG. 5, the laser projector 34 emits a relatively large laser beam having a spot size of, for example, 1 mm × 40 m as shown in FIG. 5, and the spot size is smaller than this. , Illustration For example, a laser projector 52 having a diameter of 10 // m is provided. The laser projector 52 is held movably in the horizontal direction by a support portion 53 provided on the bottom surface of the support plate 39. An arm is attached to the side of the laser projector 5 2 so as to extend to the center hole 41, and a mirror 55 is fixed to the end of the arm 54.The laser emitted from the laser projector 52 is reflected by the mirror 55. The light is reflected and is incident on the ゥヱ C 12. The rear end of the laser projector 52 is driven by the air cylinder 56 attached to the bottom of the support plate 39, and the center of the irradiation point on the laser beam 12 of the laser projector 52 is focused on the electron beam. It can be made to coincide with the irradiation point 50 on 12 or shifted from this.

The laser projector 51 is mounted diagonally with respect to the horizontal plane on the holder 57 attached to the laser projector 52, and the irradiation point on the center of the laser beam of the laser projector 51 and the laser projector 5 The center of the laser beam of No. 2 is always coincident with the irradiation point on C 1 2. Each of the laser projectors 51 and 52 has a lens system so that the focal position of the laser beam and the radiation direction of the laser beam can be finely adjusted.

When the tip of the laser projector 34 is positioned in the electron beam path, it is important that the center of the laser beam irradiates the irradiation point 50 on the electron beam 12. At this point, in this embodiment, when the laser projector 34 is moved inward, the outer flange 91 of the laser projector 34 is engaged with the support portion 53 and positioned. In this state, although not shown in the figure, the laser projector 34 has a built-in optical system adjusting mechanism as described above, and adjusts this to irradiate the electron beam irradiation point 50 with the center of the laser beam. To be adjusted in advance. If necessary, a mechanism for finely adjusting the entire laser projector 34 with respect to the support plate 39 in the X, Υ, and Z axis directions is provided, thereby irradiating the irradiation point at the center of the laser beam. It can be made to coincide with the point 50. As shown in Fig. 5, the support bin 61 is set up on the support plate 39 at an appropriate interval on the support plate 39 around the center hole 41, and The support ring 62 is fixed on the pin 61, the flange of the electron gun 16 is engaged on the support ring 62, and the electron gun 16 is supported by the support plate 39. 0 ring between the cylindrical part of the support ring 62 and the outer periphery of the electron gun 16 Ring 63 is interposed, and is kept airtight with the outside.

Fig. 6 shows the mounting structure of the laser scattered light detector 35. The laser scattered light detector 35 is mounted on the fixed base 65 on the support plate 39 so as to be able to rotate slightly in the vertical plane around the center 666, and the focal point is located on the base ゥヱ of the electron beam. It is adjusted so as to coincide with the irradiation point 50 of.

Figure 7 shows the mounting structure of the X-ray component analyzer 37. Similarly to the insertion portion of the electron gun 16 of the vacuum container 30, an opening portion of the X-ray component analyzer 37 is formed in the vacuum container 30, and the X-ray component analyzer 37 is inserted into the insertion portion. The tip is at a position where the laser beam projector 34, the laser scattered light detector 35, the secondary electron detector 17, etc. do not obstruct the electron beam irradiation point 50 on the wafer 12 relatively close to the irradiation point 50. For the initial adjustment of this position, the middle part of the X-ray component analyzer 37 is inserted and held in the cylindrical holder 71 by screw connection, and the cylindrical holder 71 is fixed outside the vacuum vessel 30. When the adjustment handle 72 is rotated, the intermediate portion of the X-ray component splitter 37 inside the cylindrical holder 71 is moved by a gear connection not shown in the figure, and based on the screw connection, The position is adjusted back and forth. A liquid vaginal element tank # 3 is attached to the outer end of the X-ray component analyzer 37, and the liquid vaginal element cools the X-ray component analyzer 37 to perform a desired analyzing action. An O-ring 74 is interposed between the outer periphery of the X-ray component analyzer 37 and its vacuum container insertion part.

Fig. 8 shows the mounting structure of the backscattered electron detector 36. The backscattered electron detector 36 is movably mounted on the lower side of the support plate 39 in a horizontal plane, and a backscattered electron detection sensor is mounted at the bottom of the tip. A small hole 95 through which the electron beam passes is formed at this tip. As shown in FIG. 6A, the support bridge 76 is shown across the rectangular hole 46 of the support plate 39, and on the support bridge 76. (The upper part of the line segmenter 36 engages with the keyway. Thus, it is held movably in the horizontal direction.

An electron beam passage hole is formed at the tip of the backscattered electron detector 36, which is removed from the position when irradiating the laser beam. Therefore, the backscattered electron detector 36 is movable in the radiation direction. Positioning is performed by 9 3 and 9 4. This movement is not shown in the figure, but is performed by, for example, an air cylinder in the same manner as for the laser projector 34.

Next, the operation of detecting and analyzing foreign matter using this foreign matter separating apparatus will be described. (See also Figure 9.) First, the laser irradiation point of the laser projector 34 is matched with the electron beam irradiation point 50, and the XY stage 32 is moved in the XY direction by the control driving device (not shown) of the control unit 40. The laser beam is emitted from the projector 51 to the laser beam 12 (S 1). The XY stage 32 is moved so that the laser beam can run on the entire surface of the laser 12. The X-direction encoder 13 when the scattered light from the foreign object is observed by the laser scattered light detector 35 The X-direction encoder 13 The reading of 13 y is stored in the storage unit 81 in the control unit 40 every time scattered light is detected (S 2, S 3). At this time, it is assumed that the spot size of the laser of the laser projector 51 used is about 100 μm, in this example 1 mm × 40 μm, and the movement pitch of the XY stage 32 is also 1 in the X direction. If the distance is set to 0 0 0 〃m and 40 に m in the Y direction, the time required to scan the entire surface of the wafer 12 is about 1 to 2 minutes, and a foreign object detection map on the wafer 12 can be obtained at high speed. (S4) (in this example, the mesh of the foreign object detection map is 100mX40m). However, although it is possible to perform the full inspection of (12) at high speed, the resolution is too poor and it is not known where the detected foreign matter is located in the range of 100 / mX40m.

Next, when a foreign substance is detected by the scanning (S5), the laser projector 51 is turned off, and the laser beam is emitted from the laser projector 52 by the laser projector 52 having a small spot size (for example, a diameter of about 10 m). Irradiate 2 The XY stage 32 is moved (S6) so that the laser beam can scan within the range of 100 〃mX40 上の m on the wafer stored in the storage unit 81 earlier (S6), and the scattered light from the foreign matter is reduced. The readings of the X-direction encoder 13 and the X-direction encoder 13 when observed by the laser scattered light detector 35 are stored again. At this time, if the moving pitch of the XY stage 32 is set to 10 μm, which is almost the same as the laser beam spot size of the laser projector 52, the time required to move in the range of 100 × mx 40 m is 1, It is about 2 seconds. At this stage, the detected foreign object is located within the range of 10m x 10 ^ m. By performing the two-stage scanning in this way, it is possible to detect a foreign object position with a resolution of 10 m in a much shorter time than in the case of performing only one-stage scanning. In addition, a relatively high resolution can be obtained.

According to the present invention, it is possible to detect a foreign object position with a higher resolution. This For this reason, a laser beam is emitted from the laser projector 52 with a small spot size to the foreign object positioned within the range of 10m X 10m, and the moving pitch of the XY stage 32 is set to 1m. (S7, S8). Even if the spot size of the laser beam from the laser projector 52 is 10 μm, the intensity distribution in the cross section of the laser beam is generally not constant within this spot, but has a certain distribution (Gaussian distribution). The more you go to the center, the stronger the strength. Therefore, if the XY stage 32 is stopped when the intensity of the scattered light from the foreign substance observed by the laser scattering hole detector 35 is maximized, the foreign substance position can be detected within a range of 1 mx 1 m. (S9). It takes about 3 seconds to move the range of 10 / mx10m in 1 ^ m bitches. With the above operation, the foreign object position can be detected with a resolution of 1 mx 1 m. Further, when performing foreign particle analysis, a scanning electron gun 16 irradiates an electron beam to scan a range of 1 mx 1 / m at the detected foreign particle position, thereby enlarging the component analysis within this range. It can be performed in about one minute using the dispersive X-ray detector 37 (S10). In this case, since the irradiation point 50 of the electron beam is aligned with the irradiation point of the laser beam, it is possible to shift the laser projector 34 from the center to the outside, immediately irradiate the electron beam, and start scanning. O If the secondary electrons generated together with the characteristic X-rays by electron beam irradiation are detected by the secondary electron detector 17, a secondary electron image (that is, a scanning electron microscope) can be obtained. Image SEM image) can be obtained. If there is a next stored foreign object detection position (S11), the flow returns to step S6 to scan the stored position.

By the above operation, foreign matter detection and separation on the wafer can be performed at high speed. For example, if there are 5 to 6 foreign matter on the wafer, analysis can be obtained within 10 minutes and automatically. It can be carried out. In other words, there is no factor for the operator to make a decision in the above operation.

In FIG. 4, a small hole 83 is passed through the mirror 56 of the support arm 54 in the laser projector 34 as shown by a dotted line, so that the laser projector 34 does not move. The electron beam may be applied to the wafer 12. Further, as partially shown in FIG. 10, the mirror 55 is attached to the support arm 5 so as to be rotatable about a shaft 84, and the mirror 55 is rotated as necessary to beam May be removed from the irradiation path.

As shown in FIG. 11 by assigning the same reference numerals to the portions corresponding to FIG. 1, the laser projector 51 having a large beam spot and the laser projector 52 having a small beam spot may be arranged on the same straight line. In other words, in the laser projector 51, the laser beam from the laser source 51a is formed into an elongated rectangle by the optical parts 51b such as prisms and apertures, and the parallel beam 51d of the thick beam is formed by the lens 51c. The tip focusing lens

The beam is narrowed at 34a, and is incident on the irradiation point 50 with a desired spot size and shape. On the other hand, the laser projector 52 is held at the axial center position in the outer cylinder 34b of the projector 34, and the narrow beam 52b of the narrow beam is formed by the lens 52a.

The beam is narrowed at 4a, and is incident on the irradiation point 50 with a desired spot size and shape.

As shown in this example, the projection of the laser beam on the wafer 12 by the laser projector 34 and the irradiation of the electron beam on the wafer 12 by the electron gun 16 may be performed in different places. That is, as described above, after detecting foreign matter by irradiating the laser beam, the movable stage 32 is moved to a position immediately below the electron gun 16, and in the above example, the foreign matter detection position is set to an accuracy of 1 m and the electron beam It can also be used to analyze foreign components with an electron beam, and to obtain SEM images and backscattered electron images.

As shown in FIG. 12, for example, a laser beam from a laser projector 34 that mechanically integrates the thick-beam laser projector 51 and the narrow-beam laser projector 52 shown in FIG. The mirror 85 is irradiated, and the reflected light scans on a straight line passing through the irradiation point 50 of the electron beam so that a scanning line 86 is formed. Each time the laser beam performs one scan, the foreign object can be detected at a high speed by moving the movable stage 32 by a distance corresponding to the spot size of the laser beam in a direction perpendicular to the scanning line 86. Scanning the wafer 12 by oscillating (reciprocatingly rotating) the laser beam in this manner is not limited to the use of the polygon mirror 85, but may be performed, for example, by a mirror attached to a movable coil used in a force ruvanometer. Can also.

When scanning the wafer 12 by shaking (rotating) the laser beam in this manner, the scanning line 86 of the laser beam is, for example, as shown in FIG. Electron beam irradiation point 50 force, constant distance d! May be separated. As shown in FIG. 14, a laser beam projection angle 0, from the laser projector 51 to the laser beam ₁₂ , is different from a laser beam projection angle 02 from the laser projector 52 to the laser beam 12. This is also the case with the example shown in FIG. 5, and the laser projectors 51 and 52 can be integrally held as shown in FIG.

In general, as the manufacturing process of a semiconductor integrated circuit wafer progresses, wirings and films formed on the wafer surface become more complicated, and concavities and convexities on the surface become conspicuous. Therefore, as shown in Fig. 15, for example, when there is a foreign substance 88 in a portion that protrudes from the surface of 12 by the thickness t, the laser projector is compared with the case where there is no thick t, convex part. 5厶X _z is a detection by 2, as detected by the laser projector 5 1 △ X, only the position shift occurs. The detection positions of the two laser projectors 5 1 and 52 with respect to the same foreign matter 8 8 are as follows. When the irradiation angles are changed to 6 and Θ z, respectively, when there is a foreign matter 8 8 on the convex part, Δ χ (= Α χ , — Χ ₂ ) is observed. Here, based on the observed Δ χ and the known angles 0,, θ を, the position where the electron beam is actually irradiated by the scanning electron 统 16 from the position where the foreign matter is detected by the laser beam is corrected (laser projector 5 that it from the second detection position delta X _zeta,厶that it from the detection position of the laser projector 5 1 X,) can be. The calculation is described below.

Relationship between the positional deviation delta chi ₂ and irradiation angle 0 ₂ and a surface convex portion in the thickness t by the laser projector 5 2 is given by the following equation.

tan 0 ₂ = t / m χ ₂

Similarly, a relational expression between the positional deviation Δχ by the laser projector 51, the irradiation angle 6, and the thickness t of the surface convex portion is given by the following expression.

t a n ^, = t / A x, ― (2)

On the other hand, the observed deviation ΔX can be expressed by the following equation.

Δ χ = Δ χ, -Δ χ _ζ

The correction value from the detected position using a laser projector 5 2 a delta chi _2, a X, delta correction value from the detected position using a laser projection device 5 1, child erasing t from the above equation Thus, each correction value can be obtained.

Δ X z = mm X · tan ^ 1 / (tan ^ _z — tan ^ i)

A x, = rum x 'tan ₂ / (tan 6? _Z -t. An (9 i) "-() Assuming that the electron beam from the scanning electron gun 16 irradiates the wafer 12 almost vertically, the position of the foreign matter may be corrected based on the correction values Δ,, Δ Δ ₂ described above. Also, if the irradiation angle of the electron beam from the scanning electron gun 16 and the irradiation angle of the laser projector 52 having the smaller beam spot are made the same, the detection position of the laser projector 52 and the laser projector 51 The deviation ΔX from the detection position due to the above becomes the correction value as it is. The appropriate difference between θ 1 and ₂ is between 20 ° and 80 °.

As shown in Fig. 16, a laser projector 34 is attached to the upper part of the electron gun 16 where the electron beam is not spread, and the laser beam from the laser projector 34 is mirrored.

According to 89, it may be made to be incident on the irradiation point 50 on the substrate 12 substantially in parallel with the electron beam 91 in the electron gun 16. Alternatively, as shown in FIG. 17, a laser projector 34 is arranged in a space where the electron beam 91 in the middle of the electron gun 16 is narrowed by being narrowed so as not to interfere with the electron beam 91, and The laser beam from the laser projector 34 is reflected by the mirror 92 formed with a small hole through which the electron beam 91 passes at the place where the electron beam 91 is narrowed so that the laser beam enters the irradiation point 50. It may be. Further, instead of fixedly disposing the mirror 92 in FIG. 17, a surface moving mirror 93 is provided as shown in FIG. 18, and when the laser beam is incident on the wafer 12, the mirror 93 is connected to the electron beam 9. When irradiating the electron beam 9 1 to the laser beam 1 2

93 may be removed from the path of the electron beam 91.

In the above description, if a thick laser beam with a square cross section such as 100 〃m x 400 〃m is used, when a foreign object is detected, the inside is further searched when a narrow laser beam is used to search for a foreign object. easy. The cross-sectional shape of this thick laser beam may be circular. In addition, the ratio of the spot size of the thick laser beam to that of the narrow laser beam may be about 10 to 200. The power to detect a foreign object with a thin laser beam and run the laser beam at a pitch smaller than the spot size as described above in order to achieve a position detection accuracy higher than the spot size. It is determined according to the detection accuracy to be used, and it is not always necessary to use the unit of 1 m. When component analysis is performed by electron beam scanning after this detection, the analysis time is lengthened if the area is large. Therefore, the scanning pitch of the laser beam for obtaining high accuracy is, for example, 0.2 i ir! About 3.0 m is appropriate. In the above description, after scanning with a thin laser beam, scanning was performed with a pitch smaller than the spot size, but this may be omitted. Also in this case, the detection speed can be remarkably improved as compared with the case where a foreign substance is detected by scanning only with a thin laser beam. Furthermore, using the intensity distribution of the cross section of the laser beam, scanning at a pitch smaller than the spot size, finding the position where the laser scattered light has the maximum intensity, and detecting foreign matter with high positional accuracy. The two-stage scanning of beam scanning and narrow laser beam scanning need not be performed, that is, thick laser beam scanning may be omitted as in the related art.

Further, as described above, the foreign substance detection and the composition analysis of the foreign substance need not be performed in the same place. However, particularly when analyzing with high positional accuracy, it is relatively difficult to move the movable stage from the foreign matter detection location to the composition analysis location at high speed. From the viewpoint of high speed and high accuracy, electron beam It is preferable that an electron gun and a laser projector be provided so that the irradiation point 50 on the substrate and the irradiation point of the laser beam coincide. In the above description, the present invention is applied to the detection and analysis of foreign substances in wafers, but the secondary electron detector 17 and the reflected electron detector 36 may be omitted. In the case of detecting foreign matter only, the electron gun 16 and the X-ray component analyzer 37 can be omitted.

As described above, according to the present invention, coarse scanning is performed with a thick laser beam, and a portion where a foreign object is detected is finely scanned with a narrow laser beam only in a portion of the spot range of the laser beam. Since foreign matter is detected, it can be detected faster than when foreign matter is detected only by fine scanning.

In addition, the spot detected by the fine scanning is finely scanned only at the spot size portion at a pitch smaller than the spot size of the laser beam, and at this time, the spot where the laser scattered light detected is the largest is the foreign matter position. Thus, the foreign substance position can be detected only with the resolution of the spot size of the laser beam, but the foreign substance position can be detected with a resolution equal to or smaller than the spot size of the laser beam.

Therefore, when foreign matter is separated by an electron beam, in the present invention, for example, a foreign matter position can be detected with a resolution of about 1 by a laser beam having a diameter of 10 / m, and the detection position is, for example, 0.1 m. Scanning only the range of 0'mxl.0m with an electron beam, X-ray analysis or S image or backscattered electron image can be obtained for high-speed analysis. can do.

In particular, by keeping the irradiation point of the electron beam and the irradiation point of the laser beam on the object without moving the movable stage, that is, the object to be inspected, it is possible to directly perform the process from the foreign substance detection to the composition analysis, and It is possible to move while maintaining high positional accuracy, and the speed can be increased from this point, and it is suitable for foreign matter / fractionation of in-line wafers at a semiconductor integrated circuit wafer manufacturing site.

Claims

The scope of the claims

1. A foreign substance detection and analysis device that detects and analyzes foreign substances on the surface of the inspection object.

A movable stage that is arranged in a vacuum vessel, on which the object to be inspected is mounted, and that can move the object to be inspected;

A first laser projector for irradiating the test object with a laser beam at a first spot size;

A second laser projector for irradiating the inspection object with a laser beam at a second spot size smaller than the first spot size;

A laser scattered light detector for detecting scattered light of the irradiation laser beam scattered by foreign matter on the surface of the inspection object;

Coarse scanning means for relatively moving and scanning the laser beam of the first laser projector and the movable stage;

A storage unit that stores a position of the inspection object at which the laser scattered light detector detects scattered light during scanning by the coarse scanning unit;

Fine scanning means for relatively moving the movable stage and the laser beam of the second laser projector within the range of the first spot size to scan the position of the inspection object stored in the storage unit. When,

Means for setting the position of the inspection object, in which the laser scattered light detector detects scattered light during scanning by the fine scanning means, as a foreign matter position,

Foreign substance detection equipped with

2. In the foreign matter detection / fractionation apparatus described in claim 1,

Fine scanning means for relatively moving the movable stage and the laser beam with a pitch smaller than the second spot size in the vicinity where the laser scattered light is detected in the scanning by the fine scanning means;

Means for detecting a scanning position at which the detection output of the laser scattered light detector is maximized during scanning by the fine scanning means and setting the position as a foreign matter position.

3. In the foreign matter detection / fractionation apparatus according to claim 2, An electron gun for irradiating the inspection object with an electron beam;

An X-ray analyzer that detects X-rays generated from the inspection object by the irradiation of the electron beam and divides the composition;

Scanning means for scanning the vicinity of the foreign substance position of the inspection object with the electron beam.

4. In the foreign matter detection / analysis device according to claim 3,

An irradiation point of the electron beam on the inspection object and an irradiation point of the laser beam on the inspection object are the same with the movable stage fixed.

5. In the foreign matter detection / separation device according to any one of claims 1 to 4, the first laser projector and the second laser projector are mechanically fixed to each other, and each laser from these laser projectors is fixed. The irradiation points of the beam on the object to be inspected are coincident.

6. In the foreign matter detection / analysis device according to claim 5,

A means for deflecting a laser beam from the first laser projector and a laser beam from the second laser projector to linearly scan the surface of the inspection object is provided.

7. In the foreign matter detection / fractionation apparatus according to claim 5,

The angle at which the laser beam from the first laser projector is incident on the object to be inspected is different from the angle at which the laser beam from the second laser projector is incident on the object to be inspected. And

8. Foreign matter detection and analysis equipment that detects and analyzes foreign matter present on the surface of the inspection object.

Fine scanning means for relatively moving the movable stage and the laser beam at a pitch smaller than the second spot size in the vicinity where the laser scattered light is detected in the scanning by the fine scanning means;

The detection output of the laser scattered light detector during scanning by the fine scanning means is Means for detecting a large scanning position and setting the position as a foreign matter position.

9. In the foreign matter detection / fractionation apparatus according to claim 8,

An electron gun for irradiating the inspection object with an electron beam;

An X-ray analyzer that detects X-rays generated from the inspection object by the irradiation of the electron beam and analyzes the composition;

Analysis scanning means for scanning the vicinity of the foreign substance position of the inspection object with the electron beam.

10. In the foreign matter detection and separation device described in claim 9,

An irradiation point of the electron beam on the inspection object is the same as an irradiation point of the laser beam on the inspection object with the movable stage fixed.

1 1. Foreign matter detection and analysis method for detecting and analyzing foreign matter present on the surface of the inspection object.

A rough scanning step of scanning the surface of the inspection object with a laser beam of the first spot size to obtain an approximate position of the foreign matter;

A fine scanning step of scanning the vicinity of the approximate position obtained in the coarse scanning step with a laser beam having a second spot size smaller than the first spot size to obtain a position of a foreign substance;

It is characterized by having.

1 2. In the method for detecting and analyzing foreign matter described in claim 1,

The vicinity of the position of the foreign matter determined in the fine scanning step is scanned at a pitch smaller than the second spot size, and the position where the laser scattering based on the foreign matter on the inspection object is maximized is determined as the position of the foreign matter. It has a fine scanning step.

1 3. In the method for detecting and analyzing foreign matter described in claims 11 or 12,

An electron beam is used to scan the vicinity of the position of the foreign matter thus obtained, and an analysis step of analyzing the foreign matter is provided.

1. In the method for detecting and analyzing foreign matter according to claim 13,

It is characterized in that the irradiation point of the inspection object with the laser beam and the irradiation point of the inspection object with the electron beam coincide with each other without moving the inspection object. I do.

1 5. In the foreign matter detection and analysis method of claim 13,

The scanning by the laser beam is performed by moving the inspection object, and the scanning by the electronic beam is performed by fixing the inspection object.

1 6. In the foreign matter detection / fractionation method of claim 13,

The spot size of the laser beam of the first spot size is substantially elongated and rectangular.

1 7. Foreign matter detection on the surface of the inspection object

A fine scanning step of scanning the surface of the inspection object with a laser beam to determine the position of the foreign matter; and scanning the vicinity of the position of the foreign matter determined in the fine scanning step at a pitch smaller than the spot size of the laser beam. A fine scanning step of finding a position where the laser scattering based on the foreign matter of the inspection object is maximized and setting the position of the foreign matter.

18. In the foreign matter detection and analysis method described in claim 17,

1 9. A foreign object detection / fractionation device that detects and analyzes foreign objects on the surface of the inspection object.

A movable stage on which the inspection object is placed,

A laser source for irradiating the inspection object with a laser beam,

A laser scattered light detector that detects a laser beam scattered light scattered based on the foreign matter of the inspection object,

An electron gun for irradiating the inspection object with an electron beam;

An X-ray analyzer that detects X-rays based on the irradiation of the test object with the electron beam and analyzes the composition;

And a vacuum container for accommodating this in common,

The laser source is provided in the electron gun, and the electron beam and the laser beam are applied to the same portion of the inspection object.