Apparatus and method for detecting defects in semiconductor devices

Abstract

To provide an apparatus for detecting side defects and internal defects in a singulated workpiece with high resolution.SOLUTION: At least one light source 18 is provided which generates illumination light in a wavelength range in which a workpiece 2 is transparent. A camera 6 images the light from at least one side of the workpiece 2 onto its own detector 26 by means of a lens. A stage is used to move the workpiece 2 and at least one side of the workpiece 2 is completely imaged with the camera 6.SELECTED DRAWING: Figure 5

Description

Technical Field

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[0001] The present invention relates to a workpiece defect detection device. Further, the present invention relates to a workpiece defect detection method. Additionally, the present invention relates to a computer program product disposed on a non - temporary computer - readable medium, particularly a product composed of computer - executable processing steps for operating a computer to detect defects in a workpiece.

Background Art

[0002] (Cross - Reference to Related Applications) This application claims priority based on U.S. Provisional Patent Application No. 62 / 088284, filed on December 5, 2014, and U.S.Provisional Patent Application No. 62 / 154109, filed on April 28, 2015, and hereby incorporates by reference the entire contents of both provisional patent applications into this application.

[0003] For example, Patent Document 1 discloses an infrared test for semiconductor chips. This test is performed by irradiating infrared rays onto the bottom surface of a semiconductor chip, receiving the infrared rays reflected from bonding pads, and further displaying an image of the bonding pads on a monitor. This image obtained from infrared rays contains information on whether there are defects in the bonding pads themselves or in the portion of the silicon substrate under the bonding pads, or whether there is a shift of the bonding pads with respect to the bumps.

[0004] Patent Document 2 discloses a detection device mainly used for detecting internal defects of a semiconductor material whose bandgap is greater than 1.12 eV. This detection device for detecting internal defects of a semiconductor material is composed of an optical microscope, an infrared CCD camera, a video cable, a simulation image monitor, a digital image acquisition card, a computer, and analysis - processing / display software.

[0005] <In addition, Patent Document 3 discloses a photoelectric method for recording a thermal diagram of the temperature distribution of land, which uses an infrared line scanning system on an aircraft. This device utilizes a rotary scanning mirror system that receives thermal radiation through a window. This mirror system has four reflective sides and is rotated around an axis by an electric motor. The radiation is directed by the mirror to an IR lens and then to a row of photoelectric receiver elements. The row of receiver elements is parallel to the rotation axis of the mirror system, and each receiver element is individually connected to a corresponding light-emitting diode from a plurality of LEDs by lead wires and amplification devices.

[0006] Patent Document 4 discloses an apparatus for analyzing microstructured wafer samples. The purpose of this apparatus is to increase its potential applications, particularly to reveal the structural details of wafers and other materials that are structured on both sides but whose structure is not visible under VIS or UV because the coating or intervening material is not transparent. In particular, by generating transmissive illumination that significantly improves the contrast in IR images and using IR light as reflected light, the sample can be shown simultaneously with reflected or transmitted IR light and reflected visible light.

[0007] Typical defects include lateral cracks caused by the dicing process and embedded cracks caused by internal stress between the dielectric layer and silicon structure within the device.

[0008] Figure 1 shows a conventional method for searching for side defects 9 in a semiconductor device 2 by performing a four-sided or five-sided inspection. The semiconductor device 2 has a first side 31, a second side 32, a third side 33, a fourth side 34, a top surface 4, and a bottom surface 5. In the setup shown in Figure 1, a camera 6 with a lens 7 is observing the bottom surface 5 of the semiconductor device 2. Mirrors 8 are positioned at a 45° angle to the first side 31, second side 32, third side 33, and fourth side 34 of the semiconductor device 2, respectively. In Figure 1, only the mirrors 8 positioned to the second side 32 and fourth side 34 of the semiconductor device 2 are shown.

[0009] The setup in Figure 1 yields images 10 of the first side 31, second side 32, third side 33, fourth side 34, and bottom 5 (see Figure 2). In addition, the setup in Figure 1 has a major drawback: the optical length 11 of the bottom 5 view is different from the optical lengths 12 of the first side 31 view, second side 32 view, third side 33 view, and fourth side 34 view. Therefore, there is always a trade-off between the focal point on the bottom 5 side of the semiconductor device 2 and the focal points on the first side 31, second side 32, third side 33, and fourth side 34 sides. Furthermore, a wide field of view is required for the resolution of these four side views, which will limit the usable pixel resolution. For side views smaller than 10 μm, there is no usable working setup, even with a 20 or 25 megapixel high-resolution camera. Therefore, it is not possible to obtain images with good focus and high resolution, and consequently, to distinguish existing defects from non-limiting contamination.

[0010] Figure 3 shows another example of a conventional setup, specifically detecting internal defects 9 (side defects) by observing the top surface 4 of the semiconductor device 2. There are no high-volume inspection methods suitable for detecting internal defects 9 (defects not visible from the outside). What exists are slow methods, particularly those using IR light 13 and optical system 14, and observing the back surface of the semiconductor device 2 ("IR back view"). Camera 6 detects the IR light 15 returning from the semiconductor device 2. A schematic representation of the image 16 obtained with the setup in Figure 3 is shown in Figure 4. This "IR back view" method, which detects internal defects 9 with IR light 13, also has its drawbacks. Firstly, this method is slow. Only manual, low-volume methods exist. If we want to automate and speed it up, there are significant limitations on the number of pixels and size of the IR camera 6 that can be used. In addition, the devices that work well are limited to those with bare silicon sides that IR light can reach. The trend for devices is to have protective coatings that are not transparent to IR light. A further drawback is the signal-to-noise ratio. Since reflection also occurs on the top surface 4 of semiconductor device 2, it would be difficult to distinguish top surface defects from internal defects 9.

[0011] The conventional method described above has significant drawbacks, particularly those arising from inspecting all five sides of the workpiece (separated semiconductor device). One drawback is that the focal point differs between the side and bottom surfaces of the workpiece. Because the optical length differs between the bottom view and the side view, there is always a trade-off between the focal point on the bottom side of the workpiece and the focal point on the edge (side) side of the workpiece. A further drawback is image resolution. Since a wide field of view is required for the four-side view, the usable pixel resolution will be limited. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] U.S. Patent No. 6339337 [Patent Document 2] China Utility Model No. 2791639 Specification [Patent Document 3] European Patent No. 2699071 [Patent Document 4] U.S. Patent No. 8154718 [Overview of the project] [Problems that the invention aims to solve]

[0013] The object of the present invention is to provide a device that can detect lateral and internal defects in individualized workpieces with high resolution, and that can distinguish between defects and contamination present on the surface of the workpiece. In addition, the device is required to have high throughput in order to perform time-saving quality control on such workpieces. [Means for solving the problem]

[0014] The purpose of the above is, A light source that provides illumination in a wavelength range that makes the workpiece transparent, A camera equipped with a lens, the lens imaging light from at least one surface of the workpiece onto the camera's detector, A stage for moving a workpiece and for completely imaging at least one of the above surfaces of the workpiece, This is achieved by a workpiece defect detection device equipped with [specific features / equipment].

[0015] The advantage of the apparatus of the present invention is that it can reliably detect lateral defects and internal defects in individualized workpieces, such as semiconductor devices, also known as dies. By using the apparatus of the present invention, quality control for such workpieces can be performed with high throughput.

[0016] A further object of the present invention is to provide a method for detecting lateral and internal defects in individualized workpieces with high resolution, enabling differentiation between surface contamination and existing defects on the workpiece. In addition, the method is required to have high throughput to enable quality control of such workpieces in a sufficiently short time.

[0017] The purpose of this is, A step of illuminating a portion of at least one surface of a workpiece with illumination light in a wavelength range that makes the workpiece transparent, The steps include imaging light from the above portion of at least one surface of the workpiece onto the camera's detector, The steps include performing relative motion of a stage holding a workpiece and a camera so that at least one of the above surfaces of the workpiece is fully imaged by the camera, This is achieved by a workpiece defect detection method having [specific features / features].

[0018] An advantage of the method of the present invention is that it can reliably detect lateral and internal defects in individualized workpieces, such as semiconductor devices, also known as dies. By using the method of the present invention, quality control of such workpieces can be performed with high throughput.

[0019] It is yet another object of the present invention to provide a computer program product disposed on a non-transitory computer-readable medium capable of automatically detecting side surface defects and internal defects in an individual work piece (semiconductor device) with high resolution, and thus being able to discriminate between defects and contaminants existing on the surface of the work piece. In addition, such a computer program is required to have a high throughput so as to sufficiently execute quality control on such work pieces in a very short time.

[0020] The above object is achieved by a computer program product disposed on a non-transitory computer-readable medium for detecting defects in a work piece, and controlling a computer by executing computer-executable processing steps constituting the product, placing the work piece on a stage, illuminating at least one surface of the work piece with illumination light in a wavelength range in which the work piece becomes transparent, imaging linear light on at least one surface of the work piece by directing light from at least one surface of the work piece to at least one line sensor provided in a camera in an optical setup, and moving a stage holding the work piece so that at least one surface of the work piece is completely imaged by the line sensor of the camera and is positioned at the focus of the camera during the movement of the stage. This is achieved by a computer program product capable of performing the above.

[0021] Typical defects that can be detected by the present invention are side cracks caused by the dicing process of the work piece and embedded cracks caused by internal stress in the work piece. When the work piece is a semiconductor device, internal stress can appear, for example, between a dielectric layer and a silicon structure. Note that the present invention (device, method, and computer program) is not limited to semiconductor devices and is applicable to side surface defects and internal defects in general.

[0022] Typically, infrared (IR) light capable of penetrating silicon-based semiconductor devices would be used, but the light source could be different depending on the wavelength range that makes the workpiece material transparent.

[0023] According to one aspect of the present invention, at least one of the above-described illumination sources is arranged such that illumination light is directed toward one side of a workpiece, and a camera receives light emitted from the far side of the workpiece. Since this far side of the workpiece is on the opposite side of the workpiece from the side that receives the illumination light, backlight illumination is obtained.

[0024] Another approach is to orient the workpiece so that the far side of the workpiece is oriented so that a dark-field image of that far side can be obtained relative to the side that receives illumination light.

[0025] A further aspect of the present invention is a configuration in which at least one of the above-described illumination sources is arranged such that the illumination light is directed toward the top surface of the workpiece, and a camera receives the light emitted from the top surface of the workpiece.

[0026] In an outstanding embodiment of the present invention, the camera's detector is a line sensor, and the camera is configured as a line scan camera. In this novel apparatus or method, an image is generated by using a line scan camera perpendicular to the side surface of a workpiece (semiconductor device) and moving the workpiece on an XYθ stage. According to the optical setup of the present invention, it is possible to generate a simultaneous view of at least a portion of the top surface and at least one side surface of the workpiece. Coaxial illumination and external illumination are also possible with this optical setup, and the illumination can be the same or separate in these two modes.

[0027] The camera lens images a line of light emanating from the side of the workpiece onto a line sensor. This emitted light originates from at least one illumination source arranged to provide backlighting.

[0028] The stage holding the workpiece is moved along the scanning direction perpendicular to the imaging target line. This scanning motion generates a complete image of at least one side of the workpiece.

[0029] Furthermore, a line of light from at least a portion of the top surface of the workpiece, located adjacent to one of the side surfaces of the workpiece, can be imaged onto the line sensor using the camera lens. It is also possible to arrange at least one of the above-mentioned light sources so that the light from the top surface is coaxial with the light directed onto at least a portion of the top surface of the workpiece. To generate an image of at least a portion of the workpiece, the stage holding the workpiece is moved along a scanning direction perpendicular to the imaging target line. This obtains a complete image of at least a portion of the top surface, that portion of the top surface is adjacent to at least one of the side surfaces of the workpiece.

[0030] Furthermore, by performing relative motion using the stage and camera, a complete image of each face of the workpiece can be captured, for example. Scanning each face can be performed with various speed profiles along the scanning direction. A preferred embodiment is a constant speed along the longitudinal direction of each face. Selecting a constant speed requires little software effort and yields the best image quality. As is obvious to experienced users, selecting a constant speed does not prevent the use of other speed profiles. Another embodiment involves increasing or decreasing the speed during scanning. In this embodiment, a high scanning speed is obtained at the edges and a low scanning speed is obtained at the center of each side.

[0031] According to one embodiment of the present invention, an optical setup is provided that simultaneously generates linear light images emanating from the sides of a workpiece and linear light images from the top surface of the workpiece. The linear light images from the top surface are positioned adjacent to the linear light images from each side of the workpiece. An upper mirror, a first lower mirror, and a second lower mirror are carried by the tip of the optical setup. The upper mirror captures a linear light image from a portion of the top surface of the workpiece. The first and second lower mirrors capture linear light images emanating from the sides of the workpiece. The optical setup of the present invention is designed so that the linear light images emanating from the sides of the workpiece and the linear light images from the top surface of the workpiece are simultaneously in focus.

[0032] According to one embodiment of the present invention, light from at least one light source can be individually coupled to one side of a workpiece and the top surface of the workpiece.

[0033] A beneficial approach is to place an optical waveguide between at least one of the above-mentioned light sources and the top surface and / or each side of the workpiece.

[0034] An example of a workpiece is a pieceized semiconductor device. In this case, since the silicon-based semiconductor device is transparent with respect to IR light, the wavelength range of the illumination light is set to the wavelength range of IR light.

[0035] The apparatus of the present invention has unparalleled advantages. Two views can be combined. There is no need to capture two images with separate cameras. By combining the two views, image processing can be performed based on a view that leads to a higher capture speed appropriate for defects and a view that leads to a lower level of discomfort appropriate for noise, thereby correcting the information. High-resolution images can be obtained by using a line scan camera. Images can be generated with higher resolution compared to conventional matrix cameras. When using IR light, it is possible to detect internal defects and / or improve the signal-to-noise ratio for individual defects. In addition, a top view (image of a part of the top surface) can be performed at a certain angle, generating an inspection mode similar to dark-field inspection.

[0036] The method of the present invention exhibits beneficial effects, for example, when the workpiece is a semiconductor device. Using this method, an image of a defect can be generated by using IR light traveling through the semiconductor device under inspection and by directly observing one side of the semiconductor device. Both the light source and the camera can be used in a vertical setup (straight observation / illumination of the edge) or an angled setup. Because silicon has a high refractive index (n=3.5 at λ=1200nm) and the device's edges are rough, almost all light will enter the device. This light ray will travel through the device at a small angle while emitting diffused light from the other side of the device. In this way, the device itself behaves like a diffused light source.

[0037] In a method according to one embodiment of the present invention, the physical property of silicon (which is the basic material for all semiconductor devices) that silicon becomes transparent when exposed to light with wavelengths greater than 1200 nm is utilized.

[0038] Based on this, this method will also be developed for "IR back view," but because the device itself behaves like a diffuse illuminator, the method of the present invention increases the signal-to-noise ratio and opens the way to a high-speed inspection solution. Normally, edge variations in the dicing process are smoothed by diffuse light. If there are material defects (such as cracks that should be detected), light will not be received inside the semiconductor device, and that area will appear as a dark area on the diffuse illuminator side, resulting in high contrast.

[0039] One of the key technical aspects of this invention is that the edges of semiconductor devices are neither precise nor clean (due to the dicing process of those semiconductor devices); therefore, light does not travel linearly and predictably within the semiconductor device, but rather is disturbed, resulting in a diffused light illumination. Another key technical aspect is that by observing only these edges, the inspection area is significantly smaller compared to observing the entire device (with an "IR back view" or "five-sided solution"), resulting in an opportunity to improve resolution (capture smaller defects) and perform faster inspections (because the image is still significantly smaller compared to other methods).

[0040] In one embodiment, illumination light is applied to one side of a semiconductor device; because the edge is bare silicon (derived from the dicing process), the light propagates within the semiconductor device. Because the device edge is rough (due to the dicing process), the light rays will not travel in a straight line within the device. Upon reaching the other side of the semiconductor device, the light rays incident at a small angle (less than approximately 17°) will be transmitted outside the semiconductor device. Light rays with angles of ±90° will cause the edge of the semiconductor device to illuminate like a diffuse illuminator. In contrast, when an internal defect or lateral crack is reached, normal light propagation is blocked, resulting in a 'defect-like' area appearing within the diffuse illumination device, and consequently, a high-contrast dark stain appearing in the camera image. A typical example of a crack is a disturbance within the silicon structure. Light is reflected by this disturbance and does not propagate. Therefore, light passing through this area will not be captured by the camera.

[0041] The same principle is used in other embodiments for performing inspection of semiconductor devices. In this embodiment, the inside of the semiconductor device is illuminated with IR light to provide an “angled side view.” The IR light is directed into the sample at an angle. Because the light is blocked by internal cracks, there is a change in the normally diffuse illumination that would otherwise occur on rough edges. This angled side view not only provides high resolution but also enables high-speed inspection. Individual internal or side defects appear larger and higher contrast because the normal internal light propagation is blocked by the defects. The diffuse IR light emitted from the semiconductor device is less responsive to external contamination, resulting in a higher signal-to-noise ratio for existing defects.

[0042] By shifting the focus to the inside of a semiconductor device, it becomes possible to resolve internal defects that are far from the edges. This even makes it possible to scan inside a completed semiconductor device.

[0043] According to the method of the present invention, illumination light from at least one light source is directed onto one side of the workpiece. The light emitted from the far side of the workpiece is imaged by a camera. Preferably, this camera is used to image the light emitted from the far side of the workpiece onto a line sensor using a lens.

[0044] Another embodiment of the present invention involves directing illumination light from at least one light source onto the top surface of the workpiece. In the camera, the lens acts to image the light emitted from the top surface of the workpiece. Preferably, the camera, through the action of the lens, images the light emitted from the top surface of the workpiece onto a line sensor.

[0045] A further embodiment of the present invention simultaneously generates line images of light emitted from the side of a workpiece, as well as line images of light from a portion of the top surface of the workpiece, using a certain optical setup. The portion of the top surface to be detected is the portion adjacent to each side of the workpiece.

[0046] According to one embodiment of the method of the present invention, there is a way to move the stage to image individual portions of at least two sides and the top surface of a workpiece. The method of the present invention is a) A step of performing a linear relative motion between the stage with the workpiece and the camera such that the image plane of the camera is parallel to one of the sides, b) A step of rotating the stage together with the workpiece, c) Repeat steps a) and b) until all sides of the workpiece are imaged by the camera, It holds.

[0047] The linear relative motion between the stage and the camera can be achieved by the linear motion of the camera alone. The linear motion of the camera is reversed between rotational steps.

[0048] According to a further embodiment of the method of the present invention, there is a way to move the stage to image individual portions of at least two sides and the top surface of a workpiece. The method of the present invention has the step of performing motion of the stage in the XY plane in parallel with rotating the stage so that the camera's focus remains on the individual sides during the rotational motion of the stage.

[0049] According to a further aspect of the present invention, a computer program product disposed on a non-temporary computer-readable medium for defect detection in a workpiece, which controls the computer by executing computer-executable processing steps that constitute the product, Place the workpiece on the stage, Illuminate at least one surface of the workpiece with illumination light in the wavelength range that makes the workpiece transparent. A certain optical setup directs light from at least one surface of the workpiece to at least one line sensor on the camera, thereby imaging the line of light from that at least one surface of the workpiece, and, The stage holding the workpiece is moved such that at least one surface of the workpiece is fully imaged by the camera's line sensor and remains in the camera's focus during the stage's movement. A system that makes this possible is provided.

[0050] As described above, according to one embodiment of the method of the present invention, a line scan camera perpendicular to the side surface of a semiconductor device is used. The image is generated by moving the semiconductor device on an XYθ stage. A custom optical system generates simultaneous views of at least a portion of the side and top surfaces of the semiconductor device. Coaxial illumination and external illumination are also possible with this optical setup, and the illumination can be the same or separate in these two modes. Because it is a line scan camera setup, a high-resolution image that is probably not possible with an area scan camera is guaranteed. By combining these two views relating to at least one side and one top surface, it is possible to obtain an image containing a considerable amount of information, namely an image that can pinpoint the exact location and origin of defects in the semiconductor device. Integration onto a movable stage setup enables high-speed inspection while receiving two high-resolution views.

[0051] The implementation using a line sensor camera offers unparalleled advantages. Because two views are combined, there is no need to capture two images with separate cameras. Furthermore, by combining the two views, information can be corrected through image processing that takes into account a view with a high capture speed appropriate for defects and a view with a low level of discomfort appropriate for noise. Using a line scan camera allows for the generation of images with higher resolution compared to conventional matrix cameras.

[0052] The semiconductor devices subjected to inspection are typically used in mobile devices. As mentioned above, side cracks lead to customer returns and incur high costs for device manufacturers, placing these manufacturers under strong pressure from customers to implement automated inspections and detect these side defects. Furthermore, even devices with such defects may pass electrical testing, but often fail prematurely in the field (e.g., when a mobile phone is dropped). As explained, the current methodology is clearly inadequate because it risks overlooking defects in semiconductor devices (which pose a risk of customer returns) while simultaneously discarding good devices due to less significant defects (leading to financial losses for manufacturers).

[0053] The present invention and its advantages will be further described below with reference to the following accompanying drawings. [Brief explanation of the drawing]

[0054] [Figure 1] This figure shows a conventional setup for detecting internal defects by observing the side of a semiconductor device. [Figure 2] Figure 1 is a schematic diagram of the image obtained with the setup shown. [Figure 3] This figure shows a conventional setup for detecting internal defects by observing the top surface of a semiconductor device. [Figure 4] Figure 3 is a schematic diagram of the image obtained with the setup shown. [Figure 5] This is a schematic diagram of an array in which semiconductor devices are inspected using IR illumination and viewed from the side using backlight illumination. [Figure 6] This is a schematic diagram of an array in which semiconductor devices are inspected using IR illumination and then viewed from the side using dark-field illumination. [Figure 7] This is a schematic diagram of an array in which semiconductor devices are inspected using IR illumination with an angled side view using backlight illumination. [Figure 8]This is a schematic diagram of an array that performs edge inspection of semiconductor devices using IR illumination in a side view and also performs scanning motion of the semiconductor devices. [Figure 9] This is a schematic diagram of an array that performs edge inspection of a semiconductor device using IR illumination with a top view, and also performs scanning motion of the semiconductor device. [Figure 10] This figure shows an embodiment of an array that simultaneously performs side view and top view of a semiconductor device. [Figure 11] This is a perspective view of an array performing a side view of one side of a semiconductor device. [Figure 12] This is a detailed diagram of the opticmechanical integration for side view and top view inspection of semiconductor devices. [Figure 13A] This is a schematic diagram of embodiments of linear and rotational scan modes for semiconductor devices. [Figure 13B] This is a schematic diagram of embodiments of linear and rotational scan modes for semiconductor devices. [Figure 13C] This is a schematic diagram of embodiments of linear and rotational scan modes for semiconductor devices. [Figure 13D] This is a schematic diagram of embodiments of linear and rotational scan modes for semiconductor devices. [Figure 13E] This is a schematic diagram of embodiments of linear and rotational scan modes for semiconductor devices. [Figure 14] This is a schematic diagram illustrating an embodiment of the linear rotational composite scanning motion of a semiconductor device. [Modes for carrying out the invention]

[0055] In the figures, similar elements or similar functional elements are denoted by similar reference numerals. Furthermore, for clarity, only the reference numerals necessary to discuss each figure are shown in that figure. The method and apparatus described herein can be suitably used in conjunction with IR light for defect inspection in semiconductor devices. Typically, IR light will be used so as to penetrate into the silicon of the semiconductor device. In other embodiments of the present invention, a different light source wavelength may be used. The only prerequisite is that the material of the workpiece to be inspected (semiconductor device) must be transparent in the wavelength range used. The following description refers to semiconductor devices, but this should not be understood as a limitation of the present invention. As will be apparent to experts, the principles and ideas of the present invention are applicable to all inspections of internal or lateral defects in workpieces. The application of the present invention to semiconductor devices should not be considered a limitation.

[0056] Figure 5 shows a schematic representation of an array 20 for inspecting a semiconductor device 2 using IR light 13. This array 20 is a side-view type with backlight illumination. IR light 13 generated by a light source 18 is incident perpendicularly on one of the selected sides 31, 32, 33, or 34 of the semiconductor device 2. The IR light 13 may not be made parallel, or the IR light 13 may not be incident perpendicularly on one of the selected sides 31, 32, 33, or 34 of the semiconductor device 2. With the array 20 shown here, an image of a defect 9 can be generated using the IR light 13 traveling through the semiconductor device 2. The advantages of using IR light 13 are that internal defects 9 can be found and / or the signal-to-noise ratio can be improved with respect to individual defects 9 of the semiconductor device 2.

[0057] Camera 6 uses its lens 7 to directly observe one selected side 31, 32, 33, or 34 of the semiconductor device 2. Due to the high refractive index of silicon (n=3.5 at λ=1200nm) and the roughness of the side 31, 32, 33, or 34 (edge) of the semiconductor device 2, almost all of the IR light 13 will be incident on the semiconductor device 2. The IR light rays 13 will travel through the semiconductor device 2 at a small angle and be emitted as diffused light rays 21 from the opposite side 31, 32, 33, or 34. In this configuration, the semiconductor device 2 itself behaves like a diffuse illuminator. However, when it reaches an internal defect 9 or a side crack, normal light propagation is blocked, resulting in a part that 'appears defective' under diffuse illumination. The blocking of IR light 13 is indicated by a dashed arrow 22. When the sides 31, 32, 33, and 34 are imaged by the lens 7 and camera 6, the internal defects 9 appear as high-contrast dark sections in the camera image. These cracks or internal defects 9 are typically disturbances within the silicon structure of the semiconductor device 2. The IR light 13 is reflected by these disturbances and does not propagate. Therefore, the light coming through the area of ​​the internal defect 9 will not be captured by the detector 26 in the camera 6.

[0058] Figure 6 shows another embodiment of the array 20 in which the semiconductor device 2 is inspected using IR light 13. In this embodiment, the semiconductor device 2 is inspected using IR light 13 from a light source 18. The camera 6 and its associated lens 7 are arranged so that dark-field images of each side 31, 32, 33, or 34 of the semiconductor device 2 are aligned and recorded by the camera 6. On the second surface 32, the direction of IR light propagation 23 is perpendicular to the optical axis 24 of the lens 7 provided on the camera 6.

[0059] Figure 7 shows a further embodiment of the array 20 of the present invention. IR light 13 is sent from the light source 18 to the top surface 4 of the semiconductor device 2 and into the interior of the semiconductor device 2 at an angle α. The IR light 13 propagates within the semiconductor device 2 and focuses on one of the sides 31, 32, 33, and 34 of the semiconductor device 2. At internal cracks or defects 9, the IR light 13 is blocked, and the normally diffuse illumination from one of the rough sides 31, 32, 33, and 34 (see Figure 5) is altered. The array shown in Figure 7 not only provides high resolution but also enables high-speed inspection of one of the sides 31, 32, 33, and 34 of the semiconductor device 2 (in this case, the fourth side 34 is the target of inspection). Individual internal or side defects 9 appear larger and higher contrast in the image captured by the camera 6 because normal internal light propagation is blocked by such defects. Because the diffuse IR light 33 emitted from the semiconductor device 2 has low responsiveness to external contamination of the semiconductor device 2, the signal-to-noise ratio related to the existing defect 9 increases.

[0060] As a useful alternative, by shifting the focus of the IR light 13 into the semiconductor device 2, internal defects 9 located far from the sides 31, 32, 33, and 34 of the semiconductor device 2 can also be resolved. This makes it even possible to scan inside the completed semiconductor device 2.

[0061] Figure 8 shows a schematic representation of a further embodiment of the array 20 of the present invention. The camera 6 has a line sensor 36, and one line 35 from among the sides 31, 32, 33, or 34 is imaged onto the line sensor 36 by the lens 7. The camera 6 is configured as a line scan camera. The camera 6 is moved along a certain scan direction 37. This movement can be achieved by relative motion between each side 31, 32, 33, or 34 of the semiconductor device 2 and the camera 6, in particular by relative motion along the scan direction 37 perpendicular to the line 35 to be imaged on the line sensor 36. This relative motion between each side 31, 32, 33, or 34 of the semiconductor device 2 and the camera 6 should not be interpreted as a limitation of the present invention. It is also clear that only the camera or only the semiconductor device may be moved.

[0062] The semiconductor device 2 is positioned on an XYθ stage (not shown here). This XYθ stage is moved by the line sensor 36 of the camera 6 so that images of all four sides 31, 32, 33, or 34 are generated. In the embodiment shown here, the semiconductor device 2 consists of an additional bulk semiconductor layer 40 (BSL), a silicon substrate 41, a dielectric layer 42, and a metal layer 43. Because it is a line scan camera setup, high-resolution images that would probably not be possible with an area scan camera are possible. For the side view (same as the arrangement in Figure 5), external IR light 13 is irradiated into the semiconductor device 2 (die) from the light source 18. This IR light 13 arrives from one side 31, 32, 33, or 34 of the semiconductor device 2 and is captured by the line scan camera 6 on the opposite side 31, 32, 33, or 34 of the semiconductor device 2. High-resolution images are generated from each side 31, 32, 33, or 34 of the semiconductor device 2. To illuminate the inside of the semiconductor device 2, a wavelength range that makes the semiconductor device 2 transparent is used. In a typical semiconductor device 2 (or die), this would be IR light 13.

[0063] Figure 9 is a schematic diagram of an array 20 that performs edge inspection of a semiconductor device 2 using IR illumination in a side view and also performs scanning motion of the semiconductor device 2. In this array, the camera 6 also has a line sensor 36, and a line 35 on the top surface 4 that is near one of the sides 31, 32, 33, or 34 is imaged onto the line sensor 36 by the lens 7. The beam splitter 27 directs IR light 13 from the light source 18 onto the top surface 4 of the semiconductor device 2. The coaxially returned IR light 34 from the top surface 4 of the semiconductor device 2 is captured by the line sensor 36 of the camera 6. Here again, the motion of the semiconductor device 2 along the scan direction 37 is perpendicular to the line 35 imaged on the line sensor 36 of the camera 6. This motion of the semiconductor device 2 makes it possible to generate a top view of the edge portion 30 of the top surface 4 of the semiconductor device 2, i.e., the portion near one of the sides 31, 32, 33, or 34. In Figure 9, the edge portion 30 of the top surface 4 is adjacent to the fourth side surface 34 of the semiconductor device 2.

[0064] The embodiment shown in Figure 10 represents an array 20 that simultaneously performs side view and top view inspection of a semiconductor device 2. A special optical setup 25 is provided that allows simultaneous viewing of one of the side surfaces 31, 32, 33, or 34 of the semiconductor device 2 and the top surface 4. This optical setup 25 also allows illumination of one of the side surfaces 31, 32, 33, or 34 of the semiconductor device 2 (external illumination) and illumination of the top surface 4 (coaxial illumination). In these two illumination modes (coaxial illumination and external illumination), the light sources can be the same light source or separate light sources.

[0065] By combining views of the side surfaces 31, 32, 33, or 34 and the top surface 4 of the semiconductor device 2, the images of the top surface 4 and the side surfaces 31, 32, 33, or 34 contain a considerable amount of information, making it possible to extract the precise location and origin of defects. Integration onto a movable stage setup enables not only two types of high-resolution views but also high-speed inspection.

[0066] These arrays 20 and special optical setups 25 can generate a simultaneous view of one side surface 31, 32, 33, or 34 of the semiconductor device 2 and the edge portion 30 of the top surface 4 (see Figure 9), as shown in Figure 10. In addition, two individual line sensors 36 are provided. One is used to capture an image of a portion of the top surface 4, and the other is used to capture an image of one of the adjacent side surfaces 31, 32, 33, or 34 of the top surface 4.

[0067] According to the embodiment shown herein, optical waveguides 50 are used to carry IR light 13. These optical waveguides 50 are positioned as close as possible to the semiconductor device 2 in order to illuminate the edge portion 30 of the top surface 4 and one of the adjacent sides 31, 32, 33, or 34 with the IR light 13.

[0068] Figure 11 shows a perspective view of an apparatus performing a side view of at least one of the sides 31, 32, 33, or 34 of a semiconductor device 2. The semiconductor device 2 (not shown here) is mounted on a hold with a chuck 45. The chuck 45 is mounted on a θ-stage 38, which can move linearly at least along the X-axis and Y-axis. It can also be tilted. Linear motion along the Z-axis can also be integrated. A light source 18 directs illumination light 13 onto the semiconductor device 2 on the chuck 45. In the embodiment shown here, the light sources 18 are arranged so that one side 31, 32, 33, or 34 of the semiconductor device 2 is illuminated. This arrangement of light sources 18 is called a backlight arrangement.

[0069] On the opposite side of the light source 18, an array 20 with an optical setup 25 is arranged to receive light emitted from one side 31, 32, 33, or 34 of the semiconductor device 2, particularly light emitted from the side opposite to the illuminated side 31, 32, 33, or 34 of the semiconductor device 2. The optical setup 25 is located at the tip 39 of the array 20. The array 20 is connected to a computer 32 that receives image data from the array 20. In addition, the computer 32 is connected to a controller 31 for moving the stage 38, so that each side 31, 32, 33, or 34 can be scanned by the array 20.

[0070] Figure 12 shows a detailed appearance of the optical setup 25 of array 20. This optical setup 25 allows for simultaneous side view and top view inspection of the semiconductor device 2. In the embodiment shown here, the optical setup 25 simultaneously generates linear light images emitted from the side surfaces 31, 32, 33, or 34 of the semiconductor device 2 and linear light images from at least a portion of the top surface 4 of the semiconductor device 2. As previously mentioned, the linear light from the top surface 4 is adjacent to the linear light from each of the side surfaces 31, 32, 33, or 34 of the semiconductor device 2. The tip 39 of the optical setup 25 carries an upper mirror 51, a first lower mirror 52, and a second lower mirror 53. The upper mirror 51 captures a linear light image from a portion of the top surface 4 of the semiconductor device 2. The first lower mirror 52 and the second lower mirror 53 are arranged on the tip 39 of the optical setup 25 so as to capture linear light images emitted from the side surfaces of the semiconductor device 2. The optical setup 25 is designed so that the linear light image emitted from the side surfaces 31, 32, 33, or 34 of the semiconductor device 2 and the linear light image from the top surface 4 of the semiconductor device 2 are simultaneously in focus. Their optical coupling is such that the optical path 54 through the upper mirror 51 and the optical path 55 through the first lower mirror 52 and the second lower mirror 53 can be illuminated separately.

[0071] Figures 13A to 13E show the process for inspecting the four sides 31, 32, 33, and 34 and / or the edge portion 30 of the top surface 4. When inspecting the four sides 31, 32, 33, and 34 and the edge portion 30 of the top surface 4, i.e., the portion adjacent to each side 31, 32, 33, or 34, a combined side view and top view image is obtained. The stage 38 performs the motion profile as described in the embodiments of Figures 13A to 13E. In Figure 13A, the semiconductor device 2 is placed on the stage 38. As described above, the semiconductor device 2 can also be held by a chuck (not shown here) which is mounted on the stage 38 (θ stage).

[0072] In Figure 13B, the first side surface 31 is parallel to the image plane 44 of the camera 6. Linear relative motion 46 is performed between the stage 38 with the semiconductor device 2 and the camera 6. During this motion 46, the image plane 44 of the camera 6 is kept parallel to the first side surface 31. After the scanning of the first side surface 31 is completed, the stage 38 is rotated 90° clockwise, resulting in the second side surface 32 of the semiconductor device 2 becoming parallel to the image plane 44 of the camera 6 (see Figure 13C). As shown in Figure 13C, linear relative motion 46 in the opposite direction is performed between the stage 38 with the semiconductor device 2 and the camera 6. During this motion 46, the image plane 44 of the camera 6 is parallel to the second side surface 32. After the scanning of the second side surface 32 is completed, the stage 38 is rotated 90°, resulting in the third side surface 33 of the semiconductor device 2 becoming parallel to the image plane 44 of the camera 6 (see Figure 13D). As shown in Figure 13D, a linear relative motion 46 is performed between the stage 38 with the semiconductor device 2 and the camera 6. During this motion 46, the image plane 44 of the camera 6 is parallel to the third side surface 33. After scanning of the third side surface 33 is completed, the stage 38 is rotated 90°, and the fourth side surface 34 of the semiconductor device 2 becomes parallel to the image plane 44 of the camera 6 (see Figure 13E). As shown in Figure 13E, a linear relative motion 46 in the opposite direction is performed between the stage 38 with the semiconductor device 2 and the camera 6. During this motion 46, the image plane 44 of the camera 6 is parallel to the fourth side surface 34.

[0073] As described above, with array 20 and special optical setup 25, it is also possible to image the edge portion 30 of the top surface 4 of the semiconductor device 2, that is, the edge portion 30 adjacent to each side 31, 32, 33, or 34 of the semiconductor device 2 (see Figure 9).

[0074] Figures 14A to 14F show further embodiments of the process for scanning at least four sides 31, 32, 33, and 34 of the semiconductor device 2. The motion of the stage (not shown here) and the semiconductor device 2 consists of rotational motion 56 around the center 58 of the semiconductor device 2 and linear motion 57 of the semiconductor device 2 in the XY plane defined by the X coordinate direction X and the Y coordinate direction Y. Figure 14A shows the starting point of the process for scanning the four sides 31, 32, 33, and 34 of the semiconductor device 2. The focal point 59 of the camera (not shown here) is on the first side 31. Figure 14B shows the beginning of the rotational motion 56. The center 58 of the semiconductor device 2 is simultaneously subjected to motion in the XY plane 57, and the focal point 59 remains on the first side 31 during the rotational motion 56. Figures 14C to 14E show the stages of the rotational motion 56 of the semiconductor device 2, during which the focal point 59 remains on the second side 32. Figure 14F shows the situation where the focal point 59 has reached the third side surface 33, and this focal point 59 remains on the third side surface 33 during the rotational motion 56 of the semiconductor device 2.

[0075] As shown in Figure 11, the computer 32 coordinates the rotational motion 56 with the simultaneous motion in the XY plane 57. Therefore, when the semiconductor device 2 has completed its 360° rotation, all four sides 31, 32, 33, and 34 have been imaged by the array 20. Furthermore, the computer 32 ensures that the focus 59 is firmly maintained on all four sides 31, 32, 33, and 34 throughout the full 360° rotation, thus obtaining high-quality images of all four sides 31, 32, 33, and 34.

[0076] It is believed that the apparatus, method, and computer program disclosed herein, as well as many of the advantages associated therewith, can be understood from the above description, and it is clear that various modifications can be made to the form, configuration, and arrangement of the components without deviating from the disclosed subject matter or sacrificing all of its important advantages. The forms described are merely examples.

[0077] The above description provides many specific details to give a general understanding of the embodiments of the present invention. However, the above description of exemplary embodiments of the present invention is not intended to be exclusive or to limit the invention to the specific forms disclosed. Those skilled in the art will recognize that the present invention can be carried out without one or more specific details or with other methods, components, etc. Furthermore, well-known structures or operations are not illustrated or described in order to avoid complicating the understanding of the embodiments of the present invention. While specific embodiments and examples of the present invention are described in this application for explanatory purposes, various equivalent modifications are possible within the technical scope of the present invention, as will be recognized by those skilled in the art.

[0078] The present invention may be modified in accordance with the detailed description above. The terms used in the claims below should not be interpreted as limiting the invention to the specific embodiments disclosed in the specification and claims. Rather, the technical scope of the present invention should be defined by the claims below, and should be interpreted in accordance with established theories regarding the interpretation of claims. [Explanation of Symbols]

[0079] 2 Workpiece, semiconductor device, 31 First side, 32 Second side, 33 Third side, 34 Fourth side, 4 Top surface, 5 Bottom surface, 6 Camera, 7 Lens, 8 Mirror, 9 Defect, internal defect, 10 Image, 11 Optical length, 12 Optical length, 13 IR light, illumination light, 14 Optical system, 15 Returned IR light, 16 Schematic image, 18 Light source, 19 Defect, 20 Array, 21 Diffuse ray, 22 Dashed arrow, 23 Direction of light propagation, 24 Optical axis, 25 Special optical setup, 26 Detector, 27 Beam splitter, 30 Edge portion, 31 Controller, 32 Computer, 33 Diffuse IR light, 34 Returned IR light, 35 Line, 36 Line sensor, 37 Scan direction, 38 Stage, θ stage, 39 Tip, 40 Bulk semiconductor layer, 41 42 silicon substrate, 43 dielectric layer, 44 metal layer, 44 image plane, 45 chuck, 46 linear relative motion, 50 optical waveguide, 51 upper mirror, 52 first lower mirror, 53 second lower mirror, 54 optical path, 55 optical path, 56 rotational motion (note Figure 10), 57 motion, 58 center, 59 focal point, XX coordinate direction, YY coordinate direction, ZZ coordinate direction, α angle.

Claims

1. A method for detecting defects in semiconductor devices, A step of generating a first illumination and a second illumination in a certain wavelength range, The steps include directing the first illumination toward the edge portion of the top surface of the semiconductor device, and directing the second illumination incident on one side of the semiconductor device toward the opposite side, which is adjacent to the edge portion of the semiconductor device, The steps include simultaneously performing a side view and top view inspection of the semiconductor device by using an optical system to focus an image from the edge portion of the top surface of the semiconductor device illuminated by the first illumination and an image from the side of the semiconductor device illuminated by the second illumination adjacent to the edge portion onto a camera, A method that includes this.

2. In the method according to claim 1, The camera comprises a lens and a detector. method.

3. In the method of claim 2, The detector comprises one or more sensors, and the camera images the illumination emitted from the top surface of the semiconductor device through the lens using the sensors. method.

4. In the method according to claim 1, An optical waveguide is arranged to guide the first illumination to the edge portion of the top surface of the semiconductor device. method.

5. The method according to claim 1, The wavelength range of the first illumination and the second illumination includes infrared light. method.

6. A method according to claim 1, wherein the semiconductor device includes a flaked semiconductor device.

7. A defect detection device for semiconductor devices, A first and second light source configured to provide a first illumination and a second illumination in a certain wavelength range, An optical system that simultaneously performs side view and top view inspection of a semiconductor device by directing the first illumination toward the edge portion of the top surface of the semiconductor device, and directing the second illumination incident from one side of the semiconductor device toward the opposite side adjacent to the edge portion of the semiconductor device, and simultaneously focusing the image from the edge portion of the top surface of the semiconductor device by the first illumination and the image from the side of the semiconductor device adjacent to the edge portion by the second illumination onto a camera, A device equipped with the following features.

8. In the apparatus according to claim 7, The camera is configured to image one or more defects within the semiconductor device based on the illumination emitted from and collected from the top surface of the semiconductor device. Device.

9. In the apparatus according to claim 7, The first illumination is arranged so as to be coaxial with the light emitted from the top surface of the semiconductor device. Device.

10. In the apparatus according to claim 7, further, The device includes an optical waveguide, which guides the first illumination and the second illumination to the top surface and one side surface of the semiconductor device, respectively. Device.

11. In the apparatus according to claim 7, The camera includes a lens and one or more sensors. Device.

12. In the apparatus according to claim 7, The tip of the optical system includes one or more mirrors, which collect light from the edge portion of the top surface of the semiconductor device due to the first illumination, and light emitted from the side of the semiconductor device adjacent to the edge portion due to the second illumination. Device.

13. In the apparatus according to claim 7, The semiconductor device includes a flaked semiconductor device. Device.

14. In the apparatus according to claim 7, The wavelength range of the first illumination and the second illumination includes infrared light. Device.

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