CN112014329A - Imaging system and method for internal structure of semiconductor product - Google Patents

Abstract

The invention relates to the technical field of terahertz imaging, and provides a system and a method for imaging an internal structure of a semiconductor product, wherein the system comprises an emitting device for emitting a first terahertz wave; the light modulation device is arranged close to the transmitting end of the transmitting device and used for carrying out spatial coding on the first terahertz wave transmitted by the transmitting device to form second terahertz waves with spatial distribution and penetrating through an object to be detected to obtain third terahertz waves containing internal structure image data of the object to be detected; a receiving device arranged opposite to the light modulation device and used for receiving the third terahertz wave and converting the third terahertz wave into an electric signal; and the remote terminal equipment is electrically connected with the receiving device and is used for receiving the electric signal and extracting the image data to construct an internal structure image of the object to be detected. The invention has the advantages of clearer image outline after imaging and higher imaging precision.

Description

Imaging system and method for internal structure of semiconductor product

technical field

The invention relates to the technical field of terahertz imaging, in particular to a system and method for imaging the internal structure of a semiconductor product.

Background technique

Defect detection of semiconductor chips is an important step in the process of manufacturing semiconductor chips, and determines the yield of semiconductor chips. The main ways of semiconductor chip defects include uneven internal structure of the wafer, chip internal circuit peeling, chip package lead breakage, and stress failure of packaging materials.

At present, the commonly used semiconductor defect inspection technologies in the industry are optical inspection, ultrasonic inspection, and X-ray inspection, but these technologies all have certain limitations. Optical inspection cannot see inside the semiconductor product because it cannot penetrate the packaging material of the chip and the PCB board. Due to the use of acoustic couplants during testing, ultrasonic technology is time-consuming and fouls the product, and can only be done by sampling. X-ray technology can only detect metals, not cracks, delaminations or holes in non-metallic ground inside the chip. In addition, the ionizing properties of X-rays can damage the circuit structure inside the wafer and cause personal injury to field workers.

At present, terahertz detection technology is also used for semiconductor defect detection, but due to the limitation of the limit resolution of terahertz waves, terahertz spectral imaging still has the phenomenon of relatively low imaging resolution. The difficulty of obtaining high spatial resolution for terahertz imaging systems is also an important technical problem that terahertz imaging defect detection technology cannot be widely used in the industrial field. Therefore, how to realize clearer and more accurate images based on terahertz detection technology has become a technical problem that needs to be solved urgently.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide an imaging system and method for the internal structure of a semiconductor product, aiming at how to realize the problem of clearer and higher precision imaging based on terahertz detection technology.

In order to achieve the above object, the present invention provides an imaging system for the internal structure of a semiconductor product, the system includes: a transmitter for emitting a first terahertz wave; a light modulation device disposed near the transmitter end of the transmitter for Spatially encode the first terahertz wave emitted by the transmitting device to form a second terahertz wave with spatial distribution, and penetrate the object to be measured to obtain a third terahertz wave containing image data of the internal structure of the object to be measured a receiving device arranged relative to the light modulation device, for receiving the third terahertz wave and converting it into an electrical signal; and a remote terminal device electrically connected to the receiving device for receiving the electrical signal and converting it into an electrical signal; Extracting the image data to construct an image of the internal structure of the object to be measured.

Preferably, the light modulation device comprises: a spatial light modulator arranged between the emission device and the object to be measured; a semiconductor laser arranged on the peripheral side of the spatial light modulator; and a semiconductor laser arranged on the semiconductor A digital light processor between the laser and the spatial light modulator, the digital light processor stores a mask image consistent with the outline image of the internal structure of the object to be measured; the semiconductor laser emits laser light through the The digital light processor forms an image on the spatial light modulator, and a photo-generated carrier layer corresponding to the mask picture is formed on the side of the spatial light modulator facing the emitting device.

Preferably, the system further comprises: a first lens disposed between the emitting device and the spatial light modulator for converting the first terahertz wave emitted by the emitting device from a diverging beam to a parallel beam.

Preferably, the spatial light modulator is provided with a scanning point array, and the range of the scanning point array on the spatial light modulator covers the projection range of the first terahertz wave after passing through the first lens.

Preferably, the transmitting device includes a femtosecond laser and a photoconductive transmitter; the receiving device is a photoconductive detector.

Preferably, the light modulation device further comprises: a second lens arranged between the semiconductor laser and the digital light processor, for focusing the laser light emitted by the semiconductor laser on the digital light processor .

Preferably, the system further includes: a signal amplifier arranged between the object to be measured and the receiving device, for filtering noise in the third terahertz wave.

In order to achieve the above object, the present invention further provides an imaging method of the above-mentioned semiconductor product internal structure imaging system, comprising:

Place the object to be measured between the optical modulation device and the receiving device, and turn on the transmitting device, the optical modulation device, the receiving device and the remote terminal equipment;

The first terahertz wave is sent to the light modulation device through the transmitting device, the first terahertz wave emitted by the transmitting device is spatially encoded to form a second terahertz wave with a spatial distribution, and penetrates the object to be measured to obtain a terahertz wave containing the object to be measured. The third terahertz wave of the internal structure image data;

The third terahertz wave is received by the receiving device and converted into an electrical signal, and the electrical signal is sent to the remote terminal equipment;

The image data is extracted from the electrical signal through the remote terminal equipment and the internal structure image of the object to be measured is constructed.

Preferably, after the step of "extracting image data from electrical signals through a remote terminal device and constructing an image of the internal structure of the object to be measured", the method further includes a processing step:

Smoothing and denoising processing and grayscale stretching processing are performed on the internal structure image to obtain a first image with improved definition.

Preferably, the step of "smoothing and denoising the internal structure image and grayscale stretching to obtain a first image with improved clarity" further comprises:

After smoothing and denoising processing and grayscale stretching processing, the internal structure image is subjected to binarization processing to obtain a binarized image;

Perform edge detection on the binarized image, obtain the contour area of the object to be measured, and remove the background area in the binarized image to obtain the first image.

The imaging system and method for the internal structure of a semiconductor product proposed by the present invention, the imaging system for the internal structure of a semiconductor product includes: an emission device for emitting the first terahertz wave; a light modulation device disposed near the emission end of the emission device, used for The first terahertz wave emitted by the transmitting device is spatially encoded to form a second terahertz wave with spatial distribution, and penetrates the object to be measured to obtain a third terahertz wave containing image data of the internal structure of the object to be measured; a receiving device arranged relative to the light modulation device, for receiving the third terahertz wave and converting it into an electrical signal; and a remote terminal device electrically connected to the receiving device for receiving the electrical signal and extracting the electrical signal The image data constructs an image of the internal structure of the object to be measured. The present invention has the advantages of making the contour of the imaged image clearer and the imaging accuracy higher.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

1 is a schematic structural diagram of an imaging system for the internal structure of a semiconductor product in an embodiment of the present invention;

FIG. 2 is a flowchart of an imaging method of an imaging system for an internal structure of a semiconductor product in an embodiment of the present invention.

Reference signs: 1. Transmitting device; 11. Femtosecond laser; 12. Photoconductive transmitter; 2. Optical modulation device; 21. Spatial light modulator; 22. Semiconductor laser; 23. Digital light processor; 3. Object to be measured; 4. Receiving device; 5. First lens; 6. Second lens; 7. Signal amplifier.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relationship between various components under a certain posture (as shown in the accompanying drawings). The relative positional relationship, the movement situation, etc., if the specific posture changes, the directional indication also changes accordingly.

It will also be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and should not be understood as indicating or implying their relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" and "second" may expressly or implicitly include at least one of that feature. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of such technical solutions does not exist. , is not within the scope of protection required by the present invention.

One aspect of the present invention provides an imaging system for the internal structure of a semiconductor product.

Please refer to FIG. 1 , which is a schematic diagram of the overall structure of an imaging system for the internal structure of a semiconductor product provided by the present invention. The system includes: a transmitting device 1 for transmitting a first terahertz wave; a light modulation device 2 disposed near the transmitting end of the transmitting device 1 for spatially conducting the first terahertz wave transmitted by the transmitting device 1 Encoding forms a second terahertz wave with a spatial distribution, and penetrates the object to be measured 3 to obtain a third terahertz wave containing the image data of the internal structure of the object to be measured 3; A device 4 for receiving the third terahertz wave and converting it into an electrical signal; and a remote terminal device electrically connected to the receiving device 4 for receiving the electrical signal and extracting the image data to construct the to-be-to-be The internal structure image of the object 3 is measured.

In this embodiment, the imaging system for the internal structure of a semiconductor product includes a transmitting device 1 , a light modulation device 2 , a receiving device 4 and a remote terminal device.

Specifically, the transmitting device 1 includes a femtosecond laser 11 and a photoconductive transmitter 12 , and the photoconductive transmitter can be activated by the femtosecond laser 11 to emit a first terahertz wave.

The light modulation device 2 is arranged close to the transmitting end of the transmitting device 1, and is used to spatially encode the first terahertz wave emitted by the transmitting device 1 to form a second terahertz wave with a spatial distribution, and can be obtained after penetrating the object to be measured 3. The third terahertz wave containing the image data of the internal structure of the object 3 to be measured.

Among them, the object to be tested 3 can be a semiconductor chip, and the packaging material and PCB board of the semiconductor chip are penetrated by terahertz waves, so as to obtain an image of the circuit structure inside the semiconductor chip, so as to prepare for the subsequent identification of whether there are defects in the internal structure of the semiconductor product, and at the same time Terahertz waves will not cause personal injury to field workers.

The first terahertz wave modulated by the light modulation device 2 forms a second terahertz wave with spatial distribution, so that the terahertz wave has complete structural characteristics before penetrating the object to be measured 3, that is, after being modulated by the light straightening device The second terahertz wave forms a structured light that is consistent with the internal structure outline of the object to be measured 3, and is more consistent with the internal structure outline of the object to be measured 3 in the process of penetrating the object to be measured 3, so that the contour of the image after imaging is more accurate. It is clear and has higher imaging accuracy, which solves the technical problem of relatively low imaging resolution in existing terahertz spectral imaging due to the limitation of the limit resolution of terahertz waves.

The receiving device 4 is arranged relative to the light modulation device 2, preferably a photoconductive receiver corresponding to the photoconductive transmitter 12, for receiving the third terahertz wave and converting it into an electrical signal.

A remote terminal device (not shown in the figure) is electrically connected to the receiving device 4 , preferably a computer with data processing capability, for receiving electrical signals and extracting image data to construct an image of the internal structure of the object to be measured 3 .

In a further preferred embodiment of the present invention, as shown in FIG. 1 , the light modulation device 2 includes: a spatial light modulator 21 arranged between the emission device 1 and the object to be measured 3; A semiconductor laser 22 on the peripheral side of the spatial light modulator 21; and a digital light processor 23 disposed between the semiconductor laser 22 and the spatial light modulator 21, the digital light processor A mask image that is consistent with the contour image of the internal structure of the measuring object 3; the semiconductor laser emits laser light through the digital light processor 23 to form an image on the spatial light modulator 21, and the spatial light modulator 21 is directed toward the A photo-generated carrier layer corresponding to the mask picture is formed on one side of the emitting device 1 .

In this embodiment, the light modulation device 2 includes a spatial light modulator 21 , a semiconductor laser 22 and a digital light processor 23 .

Specifically, the spatial light modulator 21 is arranged between the emission device 1 and the object to be measured 3. The spatial light modulator 21 refers to that under active control, it can modulate a certain parameter of the light field through liquid crystal molecules, for example, by modulating light The amplitude of the field modulates the phase through the refractive index, modulates the polarization state through the rotation of the polarization plane, or realizes the conversion of incoherent and coherent light, so as to write certain information into the light wave to achieve the purpose of light wave modulation. It can easily load information into a one-dimensional or two-dimensional light field, and use the advantages of wide bandwidth of light and multi-channel parallel processing to quickly process the loaded information.

The semiconductor laser 22 is provided on the peripheral side of the spatial light modulator 21 , for example, above or below the spatial light modulator 21 .

A digital light processor 23 (DLP) is arranged between the semiconductor laser 22 and the spatial light modulator 21. The digital light processor stores a mask image consistent with the contour image of the internal structure of the object to be measured 3, and the spatial light modulator 21 is provided with a scanning point array, and the range of the scanning point array on the spatial light modulator 21 covers the projection range of the first terahertz wave after passing through the first lens 5, so that the semiconductor laser emits laser light through the digital light processor 23 in the space light. The image is formed on the modulator 21, and a photo-generated carrier layer corresponding to the mask picture is formed on the side of the spatial light modulator 21 facing the emission device 1, because the photo-generated carrier layer can prevent the first terahertz wave from passing through the optical modulation. The first terahertz wave passing through the light modulator forms a second terahertz wave having a spatial distribution.

In a further preferred embodiment of the present invention, as shown in FIG. 1 , the system further includes: a first solar module disposed between the transmitting device 1 and the spatial light modulator and used for transmitting the transmitting device 1 The first lens 5 converts the Hertzian wave from a diverging beam to a parallel beam.

In this embodiment, the system further includes a first lens 5 disposed between the emission device 1 and the spatial light modulator, and the first lens 5 can convert the first terahertz wave emitted by the emission device 1 from a diverging beam into a The parallel beam is beneficial to form a second terahertz wave with complete spatial distribution after penetrating the light modulator.

In a further preferred embodiment of the present invention, as shown in FIG. 1 , the light modulation device 2 further includes: a second lens 6 disposed between the semiconductor laser 22 and the digital light processor 23, for converting The laser light emitted by the semiconductor laser 22 is focused on the digital light processor 23 .

In this embodiment, the light modulation device 2 further includes a second lens 6 arranged between the semiconductor laser 22 and the digital light processor 23, and the second lens 6 can focus the laser light emitted by the semiconductor laser 22 on the digital light processor On 23, the direction of the laser light path before irradiating the digital light processor 23 is unified.

In a further preferred embodiment of the present invention, as shown in FIG. 1 , the system further includes: a signal amplifier 7 disposed between the object to be measured 3 and the receiving device 4 for filtering the third terahertz noise in waves.

The phenomenon of low signal-to-noise ratio is prone to occur in the process of terahertz imaging of semiconductors. If the data acquisition card is directly used to collect the electrical signal of the receiving device, the noise of the electrical signal is relatively large. When the variation of the electrical signal is relatively weak, the electrical signal will be overwhelmed by the noise and cannot be effectively identified, making the pixel a blind spot. In order to solve the problem that the weak electrical signal is submerged by noise, in this embodiment, the signal amplifier 7 is selected to filter out the noise to improve the signal-to-noise ratio of the system. The principle of the signal amplifier 7 is to use the heterodyne oscillation technique to convert the measured signal into a direct current by means of frequency conversion. That is, using the signal correlation principle in the signal amplifier 7, after multiplying and integrating two periodic signals mixed with noise, the signal is detected from the noise, and the purpose of weakening the influence of the noise through cross-correlation operation is achieved.

Another aspect of the present invention provides the imaging method of the above-mentioned semiconductor product internal structure imaging system, as shown in FIG. 2 , including:

S1: Place the object to be measured 3 between the light modulation device 2 and the receiving device 4, and turn on the transmitting device 1, the light modulation device 2, the receiving device 4 and the remote terminal equipment;

S2: Send the first terahertz wave to the light modulation device 2 through the transmitting device 1, perform spatial encoding on the first terahertz wave emitted by the transmitting device 1 to form a second terahertz wave with a spatial distribution, and penetrate the object to be measured 3 obtaining the third terahertz wave containing the image data of the internal structure of the object to be measured 3;

S3: Receive the third terahertz wave through the receiving device 4 and convert it into an electrical signal, and send the electrical signal to the remote terminal device;

S4 : extracting image data from the electrical signal through a remote terminal device and constructing an image of the internal structure of the object to be measured 3 .

Further, in order to improve the subsequent identification of whether there is a product defect in the internal structure image, in this embodiment, a first image with higher definition is also obtained by processing the internal structure image.

Specifically, the step of "processing the internal structure image to obtain the first image" includes:

Smoothing and denoising processing and grayscale stretching processing are performed on the internal structure image to obtain a first image with improved definition.

Among them, the smoothing denoising process adopts Gaussian filtering, which can remove the noise in the image and improve the clarity of the image. Grayscale stretching can improve the contrast of the image, thereby improving the clarity of the image.

In another embodiment, the step of "processing the internal structure image to obtain the first image" further includes:

After smoothing and denoising processing and grayscale stretching processing, the internal structure image is subjected to binarization processing to obtain a binarized image;

Perform edge detection on the binarized image to obtain the contour area of the semiconductor product, and remove the background area in the binarized image to obtain the first image.

In this embodiment, the contour area of the semiconductor product is obtained from the binarized image through the edge detection technology, and the background area in the binarized image is removed to reduce the detection area, thereby improving the recognition accuracy of the internal structure image and reducing the The data processing pressure of the system.

It should be noted that, for the sake of simple description, the foregoing embodiments are expressed as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the described action sequence, because Certain steps may be performed in other sequences or simultaneously in accordance with the present invention. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus may be implemented in other manners. For example, the device embodiments described above are only illustrative. For example, the division of the above-mentioned units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated. to another system, or some features can be ignored, or not implemented. On the other hand, the shown or discussed mutual coupling or communication connection may be through some interfaces, indirect coupling or communication connection between devices or units, and may be in telecommunication or other forms.

The units described above as separate components may or may not be physically separated, and components shown as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit the protection scope of the invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on these embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above-mentioned embodiments, those of ordinary skill in the art can still combine, add or delete, or make other adjustments to the features in the various embodiments of the present invention according to the situation without making any creative efforts. As a result, other technical solutions that are different and do not essentially depart from the concept of the present invention are obtained, and these technical solutions also belong to the scope of protection of the present invention.

Claims (10)

1. A semiconductor product internal structure imaging system, characterized in that, comprising: a transmitting device for transmitting a first terahertz wave; The light modulation device disposed near the transmitting end of the transmitting device is used to spatially encode the first terahertz wave emitted by the transmitting device to form a second terahertz wave with spatial distribution, and penetrate the object to be measured to obtain a the third terahertz wave of the image data of the internal structure of the object to be measured; a receiving device disposed relative to the light modulation device for receiving the third terahertz wave and converting it into an electrical signal; and A remote terminal device electrically connected to the receiving device is used for receiving the electrical signal and extracting the image data to construct an image of the internal structure of the object to be measured. 2. The imaging system for the internal structure of a semiconductor product according to claim 1, wherein the light modulation device comprises: a spatial light modulator arranged between the emission device and the object to be measured; a semiconductor laser disposed on the peripheral side of the spatial light modulator; and a digital light processor disposed between the semiconductor laser and the spatial light modulator, wherein the digital light processor stores a mask image consistent with the outline image of the internal structure of the object to be measured; The laser light emitted by the semiconductor laser is imaged on the spatial light modulator through the digital light processor, and the side surface of the spatial light modulator facing the emitting device is formed to form a photogenerated image corresponding to the mask picture. carrier layer. 3. The imaging system for the internal structure of a semiconductor product according to claim 2, wherein the system further comprises: A first lens disposed between the transmitting device and the spatial light modulator for converting the first terahertz wave emitted by the transmitting device from a diverging beam to a parallel beam. 4 . The imaging system for the internal structure of a semiconductor product according to claim 3 , wherein a scanning point array is provided on the spatial light modulator, and the range of the scanning point array on the spatial light modulator covers 4 . The projection range of the first terahertz wave behind the first lens. 5. The imaging system for the internal structure of a semiconductor product according to claim 1, wherein the transmitting device comprises a femtosecond laser and a photoconductive transmitter; The receiving device is a photoconductive detector. 6. The imaging system for the internal structure of a semiconductor product according to claim 2, wherein the light modulation device further comprises: a second lens disposed between the semiconductor laser and the digital light processor, for The laser light emitted by the semiconductor laser is focused on the digital light processor. 7. The imaging system for the internal structure of a semiconductor product according to claim 1, wherein the system further comprises: A signal amplifier arranged between the object to be measured and the receiving device is used to filter the noise in the third terahertz wave. 8. An imaging method for an imaging system for an internal structure of a semiconductor product, comprising: Place the object to be measured between the optical modulation device and the receiving device, and turn on the transmitting device, the optical modulation device, the receiving device and the remote terminal equipment; The first terahertz wave is sent to the light modulation device through the transmitting device, the first terahertz wave emitted by the transmitting device is spatially encoded to form a second terahertz wave with a spatial distribution, and penetrates the object to be measured to obtain a terahertz wave containing the object to be measured. The third terahertz wave of the internal structure image data; The third terahertz wave is received by the receiving device and converted into an electrical signal, and the electrical signal is sent to the remote terminal equipment; The image data is extracted from the electrical signal through the remote terminal equipment and the internal structure image of the object to be measured is constructed. 9. The imaging method of the imaging system for the internal structure of a semiconductor product according to claim 8, wherein after the step of "extracting image data from electrical signals through a remote terminal device and constructing an image of the internal structure of the object to be measured", The method also includes the processing steps of: Smoothing and denoising processing and grayscale stretching processing are performed on the internal structure image to obtain a first image with improved definition. 10. The imaging method of the imaging system of the internal structure of a semiconductor product according to claim 9, characterized in that the "first step of performing smoothing and denoising processing and grayscale stretching processing on the internal structure image to obtain improved clarity". Image" step also includes: After smoothing and denoising processing and grayscale stretching processing, the internal structure image is subjected to binarization processing to obtain a binarized image; Perform edge detection on the binarized image, obtain the contour area of the object to be measured, and remove the background area in the binarized image to obtain the first image.

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