JP7360687B2 - Wafer inspection equipment - Google Patents

Description

The present invention relates to a wafer inspection apparatus for inspecting the presence or absence of defects such as scratches on the surface of a silicon wafer.

DSP (Double Side Polish) is performed when polishing the front surface and/or back surface of a silicon wafer. DSP may cause cracks, water marks, surface abnormalities, foreign objects, dirt, slips, and other various defects on the front and/or back surfaces of silicon wafers, and if such scratches remain, it will lead to a decrease in yield. . Therefore, it is necessary to check whether there are any scratches on the front or back side of the silicon wafer, but currently inspection is often done visually. Visual inspection requires mature technicians with many years of experience, but as the number of people with such skills is gradually aging, it is becoming difficult to ensure the quality of inspections.

Therefore, techniques for automating wafer inspection are disclosed in, for example, Patent Documents 1 and 2. The technology disclosed in Patent Document 1 includes an imaging means including a line sensor as an imaging element, an illumination means for illuminating an imaged area on the back side of the wafer so as to provide dark field illumination, and an arrangement between the imaging means and the illumination means and the wafer. wafer rotation means for rotating the wafer around the substantially circular center of the wafer.

In addition, the technology shown in Patent Document 2 uses a line sensor array sensitive to infrared light as an imaging element, making it possible to inspect the entire wafer under the same conditions and speeding up the inspection process. In addition, by providing a means for acquiring the resistivity value of the wafer, it is possible to set the illuminance of the illumination means in accordance with the acquired resistivity value, thereby making it possible to obtain an appropriate wafer inspection device for defect imaging. It is something that can provide illumination.

Japanese Patent Application Publication No. 2008-131025 Japanese Patent Application Publication No. 2010-8392

The technology shown in Patent Document 1 uses a metal halide lamp when inspecting the back side of a silicon wafer, but as a result of the inventors' experiments, it has been found that it is difficult to detect the same degree of flaws as the current visual inspection. However, there are problems in that the amount of light is small, which lowers the inspection accuracy, and the amount of light is small, which increases the imaging time, resulting in a large amount of time being spent on the inspection.

The technology shown in Patent Document 2 uses infrared rays to detect defects on the surface or inside of a silicon wafer, but since it uses infrared rays, it is easily affected by temperature changes, and because it uses infrared light, the resolution is low. The problem is that it gets worse.

The present invention uses LEDs, lasers, or their excitation light to inspect the presence or absence of cracks, water marks, surface abnormalities, foreign objects, dirt, slips, and various other defects on the surface of silicon wafers with an accuracy close to that of the current visual inspection. wafer inspection equipment.

The wafer inspection apparatus according to the present invention includes a mounting table for placing a silicon wafer to be inspected, and a mounting table that is provided so as to face the surface of the silicon wafer placed on the mounting table, and that is equipped with an LED or a laser. A light irradiation means that irradiates the surface of the silicon wafer while condensing light used as a light source or excitation light thereof, and an imaging means that images the light irradiated by the light irradiation means in a dark field or a bright field. It is something.

As described above, the wafer inspection apparatus according to the present invention includes a mounting table for mounting a silicon wafer to be inspected, and a mounting table provided to face the surface of the silicon wafer placed on the mounting table. , a light irradiation means that irradiates the surface of the silicon wafer while condensing light from an LED or laser as a light source or excitation light thereof, and imaging the light irradiated by the light irradiation means in a dark field or a bright field. Because it is equipped with an imaging means, it has a sufficient amount of light to shorten the imaging time and inspection time, and the dark-field or bright-field imaging allows it to detect various types of defects with high precision and a balance that does not deteriorate yield. This has the effect of achieving good inspection accuracy.

In other words, if the accuracy is much higher than the current visual inspection, defects that are not a problem in the product will be discovered, resulting in poor yield. Therefore, by realizing the accuracy of visual inspection, it is possible to prevent a decrease in yield while ensuring sufficient accuracy. In the present invention, defects such as scratches are detected with higher precision than visual inspection at the time of imaging, and by intentionally overlooking scratches below a certain threshold depending on the size, thickness, and imaging intensity of the scratch, it achieves accuracy close to that of visual inspection. It is also possible.

The wafer inspection apparatus according to the present invention has a bright field imaging mode in which the light irradiated by the light irradiation means is imaged in a bright field, and a wafer inspection apparatus in which the light irradiated by the light irradiation means is imaged in a dark field, as necessary. The apparatus includes a switching means for switching between dark field mode and dark field mode by adjusting the arrangement of the light irradiation means and/or the imaging means.

As described above, the wafer inspection apparatus according to the present invention has a bright field imaging mode in which the light irradiated by the light irradiation means is imaged in a bright field, and a dark field imaging mode in which the light irradiated by the light irradiation means is imaged in a dark field. Since the device is equipped with a switching means for switching between the visual field mode and the visual field mode by adjusting the arrangement of the light irradiation means and/or the imaging means, it is possible to switch between the dark field mode and the bright field mode depending on the type of scratch and the environment. This has the effect that it becomes possible to image the flaw and detect the defect with high precision.

In the wafer inspection apparatus according to the present invention, if necessary, the light irradiation means focuses the light from the light source with a long cylindrical lens having a predetermined width, and irradiates the light in the longitudinal direction of the cylindrical lens. A plurality of means and the imaging means are arranged in parallel, and the mounting table operates to move the silicon wafer in a direction perpendicular to the longitudinal direction of the cylindrical lens.

As described above, in the wafer inspection apparatus according to the present invention, the light irradiation means collects the light from the light source with a long cylindrical lens having a predetermined width, and irradiates the light in the longitudinal direction of the cylindrical lens. A plurality of means and the imaging means are arranged in parallel, and the mounting table operates to move the silicon wafer in a direction perpendicular to the longitudinal direction of the cylindrical lens. This has the effect that inspection can be carried out efficiently using the imaging means.

The wafer inspection apparatus according to the present invention virtually divides the silicon wafer to be inspected into a plurality of even-numbered areas by transversely or vertically cutting the silicon wafer to be inspected, as required, and selects an even-numbered area or The light irradiation means and the imaging means are arranged corresponding to odd-numbered areas.

As described above, in the wafer inspection apparatus according to the present invention, the silicon wafer to be inspected is virtually divided into a plurality of even-numbered areas by transversely or longitudinally, and the even-numbered area or Since the light irradiation means and the imaging means are arranged corresponding to the odd-numbered areas, it is possible to efficiently scan the entire surface of the silicon wafer by eliminating unnecessary movements. .

The wafer inspection apparatus according to the present invention linearly drives the mounting table along the dividing direction of the divided virtual areas, and inspects even-numbered areas among the even-numbered areas and inspects odd-numbered areas as necessary. When the silicon wafer is rotated 180 degrees along a plane and the rotation angle of the silicon wafer is 0 degrees, the inspection of the even-numbered region or the odd-numbered region among the divided even-numbered regions is performed. When either one of the regions is inspected and the rotation angle of the silicon wafer is 180°, the other of the even-numbered regions or the odd-numbered regions of the divided even-numbered regions is inspected. It is.

As described above, in the wafer inspection apparatus according to the present invention, the mounting table is linearly driven along the dividing direction of the divided virtual areas, and the even-numbered areas among the even-numbered areas are inspected and the odd-numbered areas are inspected. When the silicon wafer is rotated 180 degrees along a plane and the rotation angle of the silicon wafer is 0 degrees, the inspection of the even-numbered region or the odd-numbered region among the divided even-numbered regions is performed. When one of the regions is inspected and the rotation angle of the silicon wafer is 180°, the other of the even-numbered regions or the odd-numbered regions of the divided even-numbered regions is inspected. , the effect is that it is possible to separate even-numbered areas and odd-numbered areas and inspect each with high precision, and to scan the entire surface by inspecting these two areas, reducing inspection time. play.

In the wafer inspection apparatus according to the present invention, if the inspection target area to be inspected includes an edge portion of the silicon wafer, the position of the imaging means may be adjusted to the extent that the light irradiates at least in the inspection of the edge portion. The movement of the silicon wafer is controlled so that it is located inside the silicon wafer rather than the means.

As described above, in the wafer inspection apparatus according to the present invention, when the inspection target area to be inspected includes an edge portion of the silicon wafer, the position of the imaging means is set such that the position of the image pickup means is adjusted to the position of the light irradiation device at least in the inspection of the edge portion. Since the movement of the silicon wafer is controlled so that it is inside the silicon wafer rather than the means, it is possible to eliminate halation caused by specular reflection of light irradiated from the light irradiation means at the edge portion and perform accurate inspection. This has the effect of making it possible. In other words, the edge portion forms a radius from the front side to the back side when viewed from the side, and can prevent halation caused by specular reflection depending on the angle of the light irradiation means. .

The wafer inspection apparatus according to the present invention is configured such that when inspecting the inspection target area, the mounting table sequentially images an inner area of the silicon wafer from an edge portion of the silicon wafer, or The device is driven so that the edge portions of the silicon wafer are sequentially imaged from the inner region of the silicon wafer.

As described above, in the wafer inspection apparatus according to the present invention, when inspecting the inspection target area, the mounting table is configured such that images are sequentially taken of an inner area of the silicon wafer from an edge portion of the silicon wafer, or Since the edge portion of the silicon wafer is driven to be imaged sequentially from the inner region of the silicon wafer, the edge portion is not imaged in a state where halation may occur, thereby eliminating the effect of halation as described above. It has the effect of being able to

The wafer inspection apparatus according to the present invention performs the division while rotating the silicon wafer by 90 degrees or 270 degrees, if necessary, after the inspection is completed when the rotation angle of the silicon wafer is 0 degrees or 180 degrees. Inspect either the even-numbered region or the odd-numbered region among the virtual even-numbered regions generated in the same division, and then rotate the area by 180° to examine the even-numbered region among the divided even-numbered regions. Either the area or the odd-numbered area is inspected.

As described above, in the wafer inspection apparatus according to the present invention, after the inspection when the rotation angle of the silicon wafer is 0° and 180° is completed, the silicon wafer is rotated 90° or 270° and the splitting is performed. Inspect either the even-numbered region or the odd-numbered region among the virtual even-numbered regions generated in the same division, and then rotate the area by 180° to examine the even-numbered region among the divided even-numbered regions. Since either the area or the odd-numbered area is inspected, it is possible to detect direction-dependent defects that cannot be detected by scanning from one direction only by scanning from the other direction. This has the effect that the presence or absence of defects can be inspected with higher precision.

FIG. 1 is a block diagram showing the overall configuration of a wafer inspection apparatus according to a first embodiment. FIG. 2 is a side view showing the configuration of an inspection section in the wafer inspection apparatus according to the first embodiment. FIG. 2 is a top view showing the configuration of an inspection section in the wafer inspection apparatus according to the first embodiment. FIG. 3 is an image diagram of light emitted by a light emitting section in the wafer inspection apparatus according to the first embodiment. FIG. 3 is a diagram showing a positional relationship between a light irradiation section and an imaging section in the wafer inspection apparatus according to the first embodiment. FIG. 2 is a first diagram showing a movement state of a silicon wafer during inspection in the wafer inspection apparatus according to the first embodiment. FIG. 2 is a second diagram showing a movement state of a silicon wafer during inspection in the wafer inspection apparatus according to the first embodiment. FIG. 3 is a diagram showing a state in which light is specularly reflected at an edge portion of a silicon wafer in the wafer inspection apparatus according to the first embodiment. FIG. 3 is a diagram showing a moving direction (scanning direction) of a silicon wafer when imaging the front surface and/or back surface of the silicon wafer in the wafer inspection apparatus according to the first embodiment. FIG. 7 is a diagram illustrating an example of the arrangement relationship between a light irradiation unit and an imaging unit during inspection in a wafer inspection apparatus according to a second embodiment. FIG. 7 is a diagram illustrating an example of a path of light from a light irradiation unit during inspection in a wafer inspection apparatus according to a second embodiment.

(First embodiment of the present invention)
A wafer inspection apparatus according to this embodiment will be explained using FIGS. 1 to 9. The wafer inspection apparatus according to this embodiment inspects defects such as scratches on the surface of a silicon wafer using LEDs, lasers, or their excitation light. In particular, it achieves the same detection accuracy as the current visual inspection.For example, although actual groove-like scratches are reliably detected as scratches, they are removed in a later cleaning process. Watermarks, dirt, suction marks, etc. caused by polishing are made non-detectable by image processing or the like as necessary. Specifically, for example, it detects defects such as scratches with higher precision than visual inspection at the time of imaging, and intentionally overlooks scratches below a certain threshold depending on the size, thickness, and imaging intensity of the scratches, achieving accuracy close to that of visual inspection. You may also do so. That is, it is possible to arbitrarily determine the inspection accuracy to be output according to the setting of the threshold value.

FIG. 1 is a block diagram showing the overall configuration of a wafer inspection apparatus according to this embodiment. In FIG. 1, a wafer inspection apparatus 1 includes a cassette 10 that stores silicon wafers, a transfer robot 20 that takes out a silicon wafer to be inspected from the cassette 10 and places it on a mounting table, and an inspection that inspects the surface of the silicon wafer. section 30, an operation section 40 for performing operations and settings by an operator, and a control section 50 that calculates and controls operations and processing of the transport robot 20 and the inspection section 30 in accordance with the operations and settings.

As shown in FIG. 1, a computer that determines good/defective products based on inspection results, a display for outputting those results, and arithmetic functions such as the control section 50 are integrally provided with the operation section 40. Alternatively, the functions of the control computer, display, operation section 40, etc. may be configured separately from the wafer inspection apparatus 1, and the drive of the apparatus may be controlled through communication.

2 and 3 are diagrams showing the configuration of the inspection section 30 in the wafer inspection apparatus according to the present embodiment. FIG. 2 is a side view of the inspection section 30, and FIG. 3 is a top view of the inspection section 30. The inspection section 30 includes a mounting table 32 on which a silicon wafer 31 to be inspected is placed, a driving section 33 that drives the mounting table 32, and a light source 34 that emits LEDs, lasers, or their excitation light onto the surface of the silicon wafer 31. a light irradiation section 35 that irradiates the silicon wafer 31 with light, an imaging section 36 that takes a dark field image of the irradiated area of the silicon wafer 31 irradiated by the light irradiation section 35, and a computer that manages, analyzes, determines, outputs, etc. the captured information. 37.

At the time of inspection, the silicon wafer 31 is placed on the mounting table 32, and can be moved at least linearly under the control of the drive section 33. When inspecting the surface of the silicon wafer 31, care must be taken to prevent dust and dirt from adhering to the surface as much as possible. In particular, if metal pieces or the like adhere to the silicon wafer 31, metal contamination may cause problems in the functionality of the silicon wafer 31. Therefore, in this embodiment, the attachment of dust and the like to the surface of the silicon wafer 31 is prevented by moving the mounting table 32 instead of driving the light irradiation unit 35 and the imaging unit 36.

Further, although details will be described later, in this embodiment, the silicon wafer 31 is linearly reciprocated to increase inspection efficiency while suppressing costs with a minimum configuration. That is, by driving the mounting table 32 so that the light irradiation section 35 and the imaging section 36 move laterally (or vertically) relative to the silicon wafer 31, the inspection efficiency can be improved as described later. is possible.

In the light irradiation section 35, a light guide 34a is connected to the light source 34, and the tip portion of the light guide 34a is formed in an elongated shape. A cylindrical lens 34b is attached to the output end of the light guide 34a, and irradiates the silicon wafer 31 with the light while focusing the light from the light source 34. FIG. 4 is an image diagram of the light emitted by the light emitting section 35. FIG. 4(A) is an overall image diagram of the light irradiated by the light irradiation unit 35, and FIGS. 4(B) and 4(C) are diagrams showing the area used for imaging with respect to the light amount distribution of the irradiated light, FIG. 4(B) shows the region in the longitudinal direction, and FIG. 4(C) shows the region in the transverse direction.

As shown in FIG. 4(A), a cylindrical lens 34b is attached to a light guide 34a, which has an elongated tip portion with a predetermined width, and has a structure to condense the light from the light source 34. . Note that if the width in the longitudinal direction of the cylindrical lens 34b is the width dw, and the width in the short direction is the width dL, the irradiated light has a band shape on the silicon wafer 31, but the irradiated light is in the form of a band on both ends of the width dw (Fig. 4 Since the intensity of the irradiation light corresponding to A and B) in (A) and both end portions of the width dL (C and D in FIG. 4(A)) is weak, As shown in Figure 2, only areas with high light intensity may be used for inspection. In addition, in order to prevent the irradiation light corresponding to both end portions (A to D in FIG. 4(A)) from becoming weak and to make the light intensity as uniform as possible as a whole, the cylindrical lens 34b is made into an aspherical surface. It is desirable to do so.

The light source 34 outputs an LED or a laser, and by using an LED, a laser, or other excitation light from these, the intensity of light can be increased and the imaging time can be shortened compared to a light source such as a metal halide. , it is possible to shorten inspection time. In particular, excitation light excited by laser light , that is, light that is generally irradiated onto a predetermined object and emitted from the object, has a high straightness, so scattered light against scratches can be detected more effectively. In addition, since the light excited by the laser beam has a strong short wavelength with a peak around 450 nm, for example, it becomes possible to obtain an image with a resolution higher than λ/(2·NA).

The imaging unit 36 uses a line sensor as an imaging element, and performs dark field imaging. That is, the direct light emitted from the light emitting section 35 is blocked, and the light emitted from the light emitting section 35 scattered on the surface of the silicon wafer 31 is sensed. Therefore, as shown in FIG. 5, when the irradiation direction of the light irradiation unit 35 is perpendicular to the surface of the silicon wafer 31, the imaging angle of the imaging unit 36 (here, the angle with respect to the surface of the silicon wafer 31) is It is installed so that the angle α)) in FIG. 5 is a predetermined angle. It is desirable that this predetermined angle is, for example, α=60° to 80°, more preferably about 70°. Further, the imaging unit 36 is connected to a computer 37 such as a personal computer, and the imaging information captured by the imaging unit 36 is taken into the computer 37 and analyzed. As a result, it is determined whether the silicon wafer 31 to be inspected is a good product or a defective product.

Note that, as shown in FIG. 5, in this embodiment, the light from the light irradiation unit 35 is configured to be irradiated perpendicularly to the silicon wafer 31, and the imaging unit 36 is configured to irradiate the silicon wafer 31 with light as described above. The camera is installed at an angle α and images are taken. This is because the light from the light irradiation section 35 is irradiated perpendicularly to the silicon wafer 31, thereby minimizing the irradiation area of the light from the light irradiation section 35 on the silicon wafer 31 and ensuring the light intensity. This is to do so. That is, if the arrangement of the light irradiation unit 35 and the imaging unit 36 is reversed in FIG. 5, the light is irradiated from the angle α, the irradiation area on the silicon wafer 31 is expanded, and the intensity of the light is reduced. Therefore, as shown in FIG. 5, it is desirable to emit light from a vertical direction and to perform imaging from an oblique direction at an angle α.

Furthermore, when inspecting scratches using DSP, for example, the sharpness of the groove may be different between the scratches created at the initial stage of polishing and the scratches created at the final stage. That is, scratches caused by chemical mechanical polishing dissolve during polishing and become smooth. Therefore, the grooves of scratches formed at the initial stage of polishing are smooth, and the grooves become sharper as the scratches are formed later. Through verification by the inventors, when inspecting such scratches with various shapes, it is advantageous to use a light source that is strong and highly directional from the vertical direction using an LED or laser and its excitation light. It has become clear that it is possible to detect

Here, as described above, improving the inspection efficiency by linearly reciprocating the silicon wafer 31 will be described in detail. FIG. 6 is a first diagram showing the state of movement of the silicon wafer 31 during inspection. FIG. 6(A) shows the positional relationship between the silicon wafer 31, the light irradiation unit 35, and the imaging unit 36 when inspecting a half area of the silicon wafer, and FIG. 6(B) shows the positional relationship when inspecting the remaining half area. The positional relationship between the silicon wafer 31, the light irradiation section 35, and the imaging section 36 is shown.

In FIG. 6, four regions (regions 31a, 31b, 31c, and 31d) are defined so as to traverse the silicon wafer 31. As shown in FIG. 6A, the light irradiation section 35 and the imaging section 36 are arranged in parallel along the longitudinal direction of the cylindrical lens 34b at positions corresponding to odd-numbered regions (regions 31a, 31c). It is arranged as follows. In this state, the mounting table 32 moves linearly together with the silicon wafer 31 in a direction perpendicular to the longitudinal direction of the cylindrical lens 34b, that is, in a longitudinal direction of the four longitudinally traversed regions. By this movement of the mounting table 32, the areas 31a and 31c indicated by diagonal lines are inspected.

When the inspection of the region 31a and the region 31c is completed, the silicon wafer 31 is rotated 180 degrees about a line passing through the center point of the silicon wafer 31 and perpendicular to the wafer surface. In this state, as shown in FIG. 6(B), the mounting table 32 moves linearly along with the silicon wafer 31 in the longitudinal direction of the four regions. By this movement of the mounting table 32, the areas 31b and 31d shown in white are inspected. In other words, mechanically, the entire surface of the silicon wafer 31 can be inspected in its entirety just by linearly reciprocating the mounting table 32 and rotating the silicon wafer 31. Additionally, since only the minimum amount of movement is required, inspection time can be extremely shortened and work efficiency can be improved.

FIG. 7 is a second diagram showing the movement state of the silicon wafer 31 during inspection. FIG. 7(A) shows the positional relationship between the silicon wafer 31, the light irradiation section 35, and the imaging section 36 when inspecting a half area of the silicon wafer, and FIG. 7(B) shows the positional relationship when inspecting the remaining half area. The positional relationship between the silicon wafer 31, the light irradiation section 35, and the imaging section 36 is shown. Note that the process in FIG. 7 is executed after the process in FIG. 6 is performed.

Here, the difference in FIG. 7 from the case in FIG. 6 is that the silicon wafer 31 to be inspected is rotated by 90 degrees compared to the case in FIG. is the same as In FIG. 6, the notches are located on the upper end side and on the lower end side, whereas in FIG. 7, the notches are located on the left end side and the right end side. The moving direction of the silicon wafer 31 is the same as in the case of FIG. 6, but since the arrangement of the silicon wafer 31 is rotated by 90 degrees compared to the case of FIG. 6, both inspections of FIG. 6 and FIG. 7 are performed. This allows inspection to be performed from the vertical direction (longitudinal direction) and from the horizontal direction (lateral direction) in plan view, making it possible to detect defects with higher precision. That is, by performing inspection from two directions, it is possible to reliably detect defects that have direction dependence.

In FIGS. 6 and 7, the silicon wafer 31 is divided vertically into four regions; It may also be divided vertically or crosswise into any even number of areas, such as division or eight divisions. Regardless of how many divisions the silicon wafer 31 is divided into, by installing the light irradiation unit 35 and the imaging unit 36 at positions corresponding to either the odd-numbered area or the even-numbered area, it is possible to will be scanned.

In each of FIGS. 6 and 7, for example, when the mounting table 32 is inspected in one reciprocation (areas 31a and 31c are inspected on the outward pass and areas 31b and 31d are inspected on the return pass), the entire surface of the silicon wafer 31 is inspected. However, depending on the shape of the edge portion of the silicon wafer 31, the following problems may occur. Specifically, when the edge portion of the silicon wafer 31 is viewed from the side, a radius is formed from one surface to the other surface as shown in FIG. That is, as shown in FIG. 8A, when the inspection target area includes an edge portion, the light from the light source 34 is regularly reflected at a certain timing due to the radius of this edge portion, despite dark field imaging. If the image is captured, halation may occur.

In this embodiment, in order to prevent the occurrence of such halation, when inspecting the edge portion, the inspection is performed so that the imaging unit 36 is not placed outside the edge. In the state of FIG. 8(A), the light from the light irradiation section 35 is regularly reflected on the imaging section 36, causing halation, but in the state of FIG. 8(B), the light from the light irradiation section 35 There is no specular reflection on the imaging unit 36. That is, in the edge portion, the positional relationship between the light irradiation section 35 and the imaging section 36 is controlled such that the imaging section 36 is always positioned inward of the silicon wafer 31 with respect to the position of the light irradiation section 35.

FIG. 9 is a diagram showing the positional relationship between the light irradiation section 35 and the imaging section 36 when imaging the front surface and/or back surface of the silicon wafer 31, and the moving direction (scanning direction) of the silicon wafer. As described above, the imaging unit 36 is controlled so as not to be positioned further outward of the silicon wafer 31 than the light irradiation unit 35 in the inspection of the edge portion. Specifically, as shown in FIGS. 9A and 9B, when imaging the non-imaging region R in each case, the silicon wafer 31 is rotated 180 degrees and inspected . By performing such imaging, it is possible to prevent halation occurring at edge portions .

(Second embodiment of the present invention)
The wafer inspection apparatus according to this embodiment will be explained using FIGS. 10 and 11. The wafer inspection apparatus according to the present embodiment is an expanded version of the wafer inspection apparatus according to the first embodiment, and can switch between dark field inspection and bright field inspection. . Depending on the type of defect, some defects are easier to find with dark-field inspection, while others are easier to find with bright-field inspection. For example, defects such as scratches and foreign objects are easier to detect using dark field inspection, while slip defects and surface roughness caused by faults in the epitaxial layer are easier to detect using bright field inspection.

FIG. 10 is a diagram showing an example of the arrangement relationship between the light irradiation unit 35 and the imaging unit 36 during inspection in the wafer inspection apparatus according to the present embodiment, and FIG. 10A shows the arrangement relationship during dark field inspection, FIG. 10(B) shows the arrangement relationship in bright field inspection. In the case of dark field, as described above, when the light irradiation unit 35 irradiates light perpendicularly to the surface of the silicon wafer 31, the imaging angle of the imaging unit 36 is 60° to 80° (more preferably 70°). degree). On the other hand, in the case of bright field, when the light irradiation unit 35 irradiates the silicon wafer 31 with light at an angle of 60° to 80°, the imaging angle of the imaging unit 36 is also approximately 60° to 80°. will be placed in

Further, the wafer inspection apparatus 1 includes a switching section (not shown) that switches between a bright field mode for inspecting in a bright field and a dark field mode for inspecting in a dark field. It becomes possible to switch between dark field mode and bright field mode as shown in .

FIG. 11 is a diagram showing an example of the arrangement relationship between the light irradiation section 35 and the imaging section 36 during inspection in the wafer inspection apparatus according to the present embodiment. In FIG. 11, the light irradiation section 35 has a dark field light irradiation section 35a and a bright field light irradiation section 35b, and the drive of each light irradiation section is controlled by a switching section (not shown). Switch to obtain inspection results in dark field mode and bright field mode.

Note that if information on dark-field inspection results and bright-field inspection results is accumulated, automatic switching may be performed using AI by analyzing these data. For example, control can be performed such as separating dark field mode and bright field mode depending on the timing of inspection in the manufacturing process, or switching between dark field mode and/or bright field mode depending on the type of flaw to be detected. You can also do this.

In this way, in the wafer inspection apparatus according to the present embodiment, the bright field imaging mode and the dark field mode are switched by adjusting the arrangement of the light irradiation section 35 and/or the imaging section 36, so that By switching between dark field mode and bright field mode, it becomes possible to image flaws more clearly and detect defects with high precision.

1 Wafer inspection device 10 Cassette 20 Transfer robot 30 Inspection section 31 Silicon wafer 32 Mounting table 33 Drive section 34 Light source 34a Light guide 34b Cylindrical lens 35 Light irradiation section 36 Imaging section 37 Computer 40 Operation section

Claims (6)

A mounting table for mounting a silicon wafer to be inspected;
a light irradiation means that is provided to face the surface of the silicon wafer placed on the mounting table and irradiates the surface of the silicon wafer while condensing light from a light source excited by a laser;
and imaging means for imaging the light irradiated by the light irradiation means in a dark field ,
The light irradiation means irradiates the surface of the silicon wafer with light at an angle that minimizes the irradiation area of the light from the light irradiation means, and the imaging means irradiates the surface of the silicon wafer with light at an angle of 60° to 60° to the surface of the silicon wafer. At an angle of 80°, image the light from the light irradiation means irradiated onto a smooth scratch formed at least in the initial stage of polishing in a dark field;
When the positional relationship between the light irradiation means and the imaging means with respect to the silicon wafer changes as the mounting table is driven to rotate 180°, the position of the imaging means is always lower than the light irradiation means at the edge portion. A wafer inspection apparatus characterized in that the wafer inspection apparatus is controlled to be located inside the silicon wafer and further inside the silicon wafer than an edge portion of the silicon wafer. The wafer inspection apparatus according to claim 1,
The imaging means has a function of imaging the light irradiated by the light irradiation means in a bright field,
The light irradiation means and/or the A wafer inspection apparatus comprising a switching means for adjusting and switching the arrangement of an imaging means. The wafer inspection apparatus according to claim 1 or 2,
The light irradiation means collects the light from the light source with a long cylindrical lens having a predetermined width, and a plurality of the light irradiation means and the imaging means are arranged in parallel in the longitudinal direction of the cylindrical lens. Ori,
A wafer inspection apparatus in which the mounting table operates to move the silicon wafer in a direction perpendicular to the longitudinal direction of the cylindrical lens. The wafer inspection apparatus according to claim 3,
The silicon wafer to be inspected is virtually divided into a plurality of even-numbered regions by transversely or longitudinally, and the light beam is applied to either the even-numbered region or the odd-numbered region of the divided virtual regions. A wafer inspection apparatus including an irradiation means and the imaging means. The wafer inspection apparatus according to claim 4,
The mounting table is linearly driven along the dividing direction of the divided virtual area, and the silicon wafer is moved along a plane by inspecting even-numbered areas and inspecting odd-numbered areas among the even-numbered areas. Rotate 180 degrees,
When the rotation angle of the silicon wafer is 0°, either an even-numbered region or an odd-numbered region among the divided even-numbered regions is inspected;
A wafer inspection apparatus that inspects either an even-numbered region or an odd-numbered region among divided even-numbered regions when the rotation angle of the silicon wafer is 180°. The wafer inspection apparatus according to claim 5 ,
After the inspection is completed when the rotation angle of the silicon wafer is 0° and 180°, the even-numbered area of the virtual even-numbered areas generated by the same division as the above-mentioned division when the silicon wafer is rotated by 90° or 270°. Either the area or the odd-numbered area is inspected, and then the other area, either the even-numbered area or the odd-numbered area of the divided even-numbered areas, is inspected by rotating 180°. Wafer inspection equipment.

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