Semiconductor device and forming method thereof

Abstract

The embodiment of the invention provides a semiconductor device and a forming method thereof. The semiconductor device comprises a first functional layer, a first absorption layer and an avalanche layer, wherein the first absorption layer and the avalanche layer are located on the top surface and the bottom surface of the first functional layer respectively; the first absorption layer is used for absorbing photons and generating photon-generated carriers; the first functional layer is used for reflecting photons which are not absorbed by the first absorption layer back to the first absorption layer and transmitting photon-generated carriers generated by the first absorption layer to the avalanche layer; and the avalanche layer is used for enabling the photon-generated carriers entering the avalanche layer to trigger an avalanche effect so as to generate avalanche current.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a semiconductor device and a method for forming the same. Background Art

[0002] Avalanche photodiode (APD) is a semiconductor device based on the avalanche breakdown effect of PN junction. Due to its excellent photon detection capability, it is widely used in ranging and low-light imaging (such as autonomous driving, face recognition, quantum communication, medical fluorescence monitoring, etc.) scenarios. Among them, quantum efficiency is one of the important parameters to measure the performance of avalanche photodiodes. It characterizes the ability of avalanche photodiodes to absorb photons and generate electron-hole pairs, which directly affects the photon detection efficiency of avalanche photodiodes.

[0003] In the related art, high-reflectivity materials are introduced into avalanche photodiodes, so that unabsorbed photons can be reflected and then absorbed a second time, so as to improve the quantum efficiency of the avalanche photodiode; however, due to the long delay between the absorption time of the photons that are absorbed again after the second reflection (or multiple reflections) (referred to as "reflected photons") and the photons that are directly absorbed for the first time (referred to as "direct photons"), the time consistency of the avalanche signals generated by different avalanche photodiode pixels due to the absorption of reflected photons or direct photons is affected, resulting in poor imaging effects. Summary of the invention

[0004] Embodiments of the present disclosure provide a semiconductor device and a method for forming the same.

[0005] In a first aspect, an embodiment of the present disclosure provides a semiconductor device, comprising: a first functional layer, and a first absorption layer and an avalanche layer respectively located on a top surface and a bottom surface of the first functional layer;

[0006] The first absorption layer is used to absorb photons and generate photogenerated carriers;

[0007] The first functional layer is used to reflect photons not absorbed by the first absorption layer back to the first absorption layer, and to transmit photogenerated carriers generated by the first absorption layer to the avalanche layer;

[0008] The avalanche layer is used to cause the photogenerated carriers entering therein to trigger an avalanche effect and generate an avalanche current.

[0009] In some embodiments, the first functional layer includes a channel structure and a first reflective structure located outside the channel structure;

[0010] The channel structure is used to transfer the carriers generated by the first absorption layer to the avalanche layer;

[0011] The first reflective structure is used to reflect photons that are not absorbed by the first absorption layer.

[0012] In some embodiments, an etching rate of the material of the channel structure is greater than an etching rate of the material of the first absorption layer and an etching rate of the material of the avalanche layer.

[0013] In some embodiments, the mobility of photogenerated carriers in the channel structure is higher than that in the first absorption layer.

[0014] In some embodiments, the first reflective structure includes a structural support layer and an insulating reflective layer, and the insulating reflective layer is located at the interface between the structural support layer and the first absorption layer, the channel structure, and the avalanche layer.

[0015] In some embodiments, in the first direction, the size of the channel structure is 1 / 10 to 1 / 3 of the size of the first functional layer;

[0016] In the second direction, the size of the channel structure is 1 / 10 to 1 / 3 of the size of the semiconductor device;

[0017] The first direction is parallel to the plane where the first functional layer is located; and the second direction is perpendicular to the plane where the first functional layer is located.

[0018] In some embodiments, the semiconductor device further includes: a second absorption layer located on a side of the first absorption layer away from the first functional layer;

[0019] The material composition of the second absorption layer is the same as that of the channel structure.

[0020] In some embodiments, an etching rate of the material of the channel structure is greater than an etching rate of the material of the second absorption layer.

[0021] In some embodiments, the materials of the second absorption layer and the channel structure are germanium silicon materials, and the concentration of germanium in the material of the second absorption layer is lower than the concentration of germanium in the material of the channel structure.

[0022] In a second aspect, an embodiment of the present disclosure provides a method for forming a semiconductor device, the method comprising:

[0023] Providing an initial stacking structure, the initial stacking structure comprising a first initial functional layer, and a first initial absorption layer and an initial avalanche layer respectively located on the top surface and the bottom surface of the first initial functional layer;

[0024] Etching the initial stacking structure to form an etched structure; the etched structure includes a channel structure formed after etching the first initial functional layer, a first etched groove around the channel structure, a first absorption layer formed after etching the first initial absorption layer, and an avalanche layer formed after etching the initial avalanche layer;

[0025] The etched structure is filled to form the semiconductor device; the semiconductor device includes a first absorption layer, a first functional layer and an avalanche layer, the first functional layer includes the channel structure and a first reflective structure filling the first etched groove around the channel structure.

[0026] In some embodiments, the initial stacking structure further includes a second initial absorption layer and a surface sacrificial layer located on a side of the first initial absorption layer away from the first initial functional layer, and the method further includes:

[0027] When etching the initial stack structure to form an etched structure, the second initial absorption layer and the surface sacrificial layer are etched simultaneously to form a second absorption layer and a second etched groove around the second absorption layer;

[0028] After forming the second absorption layer, the surface sacrificial layer is removed, so that the second absorption layer is located on the surface of the semiconductor device.

[0029] The embodiments of the present disclosure provide a semiconductor device and a method for forming the same; wherein the semiconductor device includes: a first functional layer and a first absorption layer and an avalanche layer respectively located on the top surface and the bottom surface of the first functional layer; the first absorption layer is used to absorb photons and generate photogenerated carriers; the first functional layer is used to reflect photons that are not absorbed by the first absorption layer back to the first absorption layer, and to transmit the photogenerated carriers generated by the first absorption layer to the avalanche layer; the avalanche layer is used to cause the photogenerated carriers entering therein to trigger an avalanche effect and generate an avalanche current. Here, a first functional layer is arranged between the absorption layer and the avalanche layer. The first functional layer can reflect photons that are not absorbed by the first absorption layer back to the first absorption layer, and the photogenerated carriers generated by absorbing photons in the first absorption layer can reach the avalanche zone layer through the first functional layer to generate an avalanche signal. Since the first functional layer is adjacent to the first absorption layer, the optical path difference between the photons absorbed by the second reflection (referred to as "reflected photons") and the photons absorbed at the first time (referred to as "direct photons") is small, so that different avalanche photodiode pixels will not have a large time difference in generating photogenerated carriers after absorbing reflected photons and direct photons, thereby ensuring the time consistency of the avalanche signal and achieving a better imaging effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the energy band structure of an indirect band gap semiconductor;

[0031] Figure 2 It is a schematic diagram of the structure of a semiconductor device in the related art;

[0032] Figure 3 A schematic diagram of a semiconductor device provided in an embodiment of the present disclosure Figure 1 ;

[0033] Figure 4 A schematic diagram of a semiconductor device provided in an embodiment of the present disclosure Figure 2 ;

[0034] Figure 5 A schematic diagram of a semiconductor device provided in an embodiment of the present disclosure Figure 3 ;

[0035] Figure 6 A schematic diagram of a semiconductor device provided in an embodiment of the present disclosure Figure 4 ;

[0036] Figure 7 A schematic diagram of a semiconductor device provided in an embodiment of the present disclosure Figure 5 ;

[0037] Figure 8 A schematic diagram of a semiconductor device provided in an embodiment of the present disclosure Figure 6 ;

[0038] Fig. 9 A schematic flow chart of a method for forming a semiconductor device provided in an embodiment of the present disclosure;

[0039] Figures 10a to 10d A schematic diagram of a structure in a semiconductor device formation process provided by an embodiment of the present disclosure;

[0040] Fig.11 A schematic flow chart of another method for forming a semiconductor device provided in an embodiment of the present disclosure;

[0041] Fig.12a and Figure 12b A schematic diagram of the structure of another semiconductor device during the formation process provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. It is understood that the specific embodiments described herein are only used to explain the relevant disclosure, rather than to limit the disclosure. It should also be noted that, for the convenience of description, only the parts related to the relevant disclosure are shown in the drawings.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. The terms used herein are only for the purpose of describing the embodiments of the present disclosure and are not intended to limit the present disclosure.

[0044] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0045] It should be pointed out that the terms "first\second\third" involved in the embodiments of the present disclosure are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of the present disclosure described here can be implemented in an order other than that illustrated or described here.

[0046] Before further describing the embodiments of the present disclosure in detail, the nouns and terms involved in the embodiments of the present disclosure are described first. The nouns and terms involved in the embodiments of the present disclosure are subject to the following interpretations:

[0047] Photon detection efficiency (PDE) is one of the most important parameters for evaluating the performance of avalanche photodiode (APD) devices. It is defined as the ratio of the number of photons detected by the avalanche photodiode to the number of incident photons. It is determined by parameters such as quantum efficiency, avalanche breakdown probability, and fill factor. In general, it is believed that the higher the PDE, the better the device performance and the more sensitive it is to photon detection. Specifically, the PDE determining factors are: PDE = quantum efficiency * avalanche breakdown probability * filling factor. Among them, quantum efficiency characterizes the ability of semiconductor materials to absorb photons and generate electron-hole pairs, which is related to the wavelength of light and the semiconductor band structure.

[0048] Traditional avalanche photodiodes are mostly silicon-based APDs. Since silicon is an indirect bandgap semiconductor with a wide bandgap width (Eg≈1.12eV), its photon absorption process requires not only that the photon energy (hv) is greater than the bandgap width (Eg), but also that phonons are assisted, such as Figure 1 As shown. Therefore, the quantum efficiency of traditional silicon-based APD is low, especially for commonly used near-infrared light sources (such as 905nm, 940nm, etc.), so the PDE of traditional silicon-based APD is limited by this.

[0049] In order to overcome the problem of low quantum efficiency of silicon-based APD, group III-V avalanche photodiodes are being actively developed in recent years. Compound semiconductors composed of group III-V elements (GaAs, GaN, ZnO, etc.) are mostly direct bandgap semiconductors, and the bandgap width can be adjusted by adjusting the molar ratio of each element, which can solve the problem of low quantum efficiency of silicon-based APD. However, its negative effect is that thermally generated carriers are also more easily excited, which in turn triggers avalanches to produce a high dark count rate (DCR), and in severe cases, it may even make the APD unable to work normally.

[0050] In addition to quantum efficiency, more important avalanche photodiode performance parameters include dark count rate (DCR), after-pulse probability, timing jitter, etc. In the process of optimizing the performance of avalanche photodiodes, it is often necessary to consider improving a certain performance parameter while ensuring that other parameters are not affected or making compromises. Obviously, the above-mentioned III-V group avalanche photodiodes cannot take into account the balance of various parameters.

[0051] In the prior art, the quantum efficiency of silicon-based avalanche photodiodes can be improved to a certain extent by introducing high reflectivity materials, such as Figure 2 As shown, the avalanche photodiode 10 includes a high reflectivity material 11, a silicon substrate 13, an avalanche region 12, an absorption region 14 and an isolation structure 15; the photons (hv) that penetrate the device are reflected by the high reflectivity material 11 and then re-enter the device, increasing the photon absorption rate. However, this technology brings new problems. For example, the photons absorbed by the secondary reflection (referred to as "reflected photons") will have a long delay with the absorption time of the photons absorbed at the first time (referred to as "direct photons"), which will affect the time consistency of the avalanche signal between different pixels and the imaging effect is not good. In addition, the problem that the photogenerated electrons generated in the non-avalanche area have a high probability of being recombined during the drift to the avalanche area has not been solved.

[0052] Based on this, an embodiment of the present disclosure provides a semiconductor device and a method for forming the same; wherein the semiconductor device includes: a first functional layer and a first absorption layer and an avalanche layer respectively located on the top surface and bottom surface of the first functional layer; the first absorption layer is used to absorb photons and generate photogenerated carriers; the first functional layer is used to reflect photons that are not absorbed by the first absorption layer back to the first absorption layer, and transmit the photogenerated carriers generated by the first absorption layer to the avalanche layer; the avalanche layer is used to cause the photogenerated carriers entering therein to trigger an avalanche effect and generate an avalanche current. Here, a first functional layer is arranged between the absorption layer and the avalanche layer. The first functional layer can reflect photons that are not absorbed by the first absorption layer back to the first absorption layer, and the photogenerated carriers generated by absorbing photons in the first absorption layer can reach the avalanche zone layer through the first functional layer to generate an avalanche signal. Since the first functional layer is adjacent to the first absorption layer, the optical path difference between the photons absorbed by the second reflection (referred to as "reflected photons") and the photons absorbed at the first time (referred to as "direct photons") is small, so that different avalanche photodiode pixels will not have a large time difference in generating photogenerated carriers after absorbing reflected photons and direct photons, thereby ensuring the time consistency of the avalanche signal and achieving a better imaging effect.

[0053] Hereinafter, the semiconductor device and the method for forming the same in the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0054] Before introducing the embodiments of the present disclosure, two directions that may be used in the following embodiments to describe the three-dimensional structure are defined. The direction parallel to the plane where the first functional layer is located is defined as the first direction, and the direction perpendicular to the plane where the first functional layer is located is defined as the second direction. In the embodiments of the present disclosure, the first direction is defined as the X-axis direction, and the second direction is defined as the Y-axis direction.

[0055] Figure 3 is an optional structural diagram of the semiconductor device 100 provided in an embodiment of the present disclosure, such as Figure 3 As shown, the semiconductor device 100 includes: a first functional layer 110, and a first absorption layer 120 and an avalanche layer 130 respectively located on the top surface and the bottom surface of the first functional layer 110. The first absorption layer 120 is used to absorb photons and generate photogenerated carriers; the first functional layer 110 is used to reflect photons that are not absorbed by the first absorption layer 120 back to the first absorption layer 120, and transmit the photogenerated carriers generated by the first absorption layer 120 to the avalanche layer 130; the avalanche layer 130 is used to cause the photogenerated carriers entering therein to trigger an avalanche effect and generate an avalanche current.

[0056] Here, photogenerated carriers refer to: under illumination conditions, electrons in the valence band of the semiconductor (i.e., the first absorption layer 120) absorb photon energy and then transition to the conduction band, thereby generating electrons in the conduction band and holes in the valence band. The formed electron-hole pairs are called photogenerated carriers.

[0057] In some embodiments, please refer to Figure 3 , the first functional layer 110 is a material layer with conductive properties and high reflectivity. On the one hand, the first functional layer 110 has a high reflectivity, and can reflect the photons that are not absorbed by the first absorption layer 120 back to the first absorption layer 120 and be reabsorbed to generate photogenerated carriers; on the other hand, the first functional layer 110 has a conductive property, and can transmit the photogenerated carriers (electrons) generated in the first absorption layer 120 to the avalanche layer 130, thereby generating an avalanche signal. Specifically, the first functional layer 110 can be a metal material layer, an alloy material layer, or an organic semiconductor material layer with high reflectivity and high conductivity. Among them, the metal material and the alloy material can be metals such as silver, copper, gold, magnesium, aluminum, titanium, tungsten, and their alloy materials, and the organic semiconductor material can be an N-type conductive polymer, such as a polymer with reflective properties and ultra-high conductivity, such as benzodifurandione (PBFDO).

[0058] It should be noted that when the first functional layer 110 is a material layer with conductive properties and high reflectivity, the electrons inside the first functional layer 110 material itself may also migrate to the avalanche layer 130 to cause an avalanche current. However, since no voltage is applied to the first functional layer 110 during the operation of the semiconductor device, the probability of the electrons inside the material itself migrating to the avalanche layer 130 is relatively low, and the probability of the photogenerated carriers (electrons) generated by the first absorption layer 120 absorbing photons migrating to the avalanche layer 130 through the first functional layer 110 is higher. Therefore, at this time, the semiconductor device can still be used as an avalanche photodiode for photon imaging, but may not have single-photon sensitivity.

[0059] In the embodiment of the present disclosure, since the first functional layer 110 is adjacent to the first absorption layer 120, the difference in optical path length between reflected photons and direct photons is small, so that different avalanche photodiode pixels will not have a large time difference in generating photogenerated carriers after absorbing reflected photons and direct photons, thereby ensuring the time consistency of the avalanche signal and achieving a better imaging effect.

[0060] In some embodiments, please refer to Figure 4 , Figure 4Another optional structural diagram of the semiconductor device 100 provided in the embodiment of the present disclosure. The first functional layer 110 may include a channel structure 111 and a first reflective structure 112 located outside the channel structure 111; the channel structure 111 is used to transfer the carriers generated by the first absorption layer 120 to the avalanche layer 130; the first reflective structure 112 is used to reflect the photons that are not absorbed by the first absorption layer 120.

[0061] In some embodiments, the mobility of photogenerated carriers in the channel structure 111 is higher than that in the first absorption layer 120 .

[0062] Here, the material of the channel structure 111 can be a germanium silicon material, for example, SiGe; the mobility of the photogenerated carriers in the channel structure 111 made of SiGe is higher than that of the first absorption layer 120 (usually made of Si), thereby reducing the recombination of the photogenerated carriers, and the photogenerated carriers can directly reach the avalanche layer 130 after passing through the channel structure 111, thereby reducing the loss of the photogenerated carriers. The material of the first reflective structure 112 is an insulating or non-insulating material with high reflectivity; wherein the non-insulating material with high reflectivity can be a metal or alloy material, for example, silver, copper, gold, magnesium, aluminum, titanium, tungsten and other metal materials and their alloy materials; the insulating material with high reflectivity can be a metal oxide material, for example, zinc oxide, titanium dioxide, etc., or can be a semiconductor material such as silicon carbide, indium nitride, etc., or can also be an organic material such as infrared reflective pigment (IR pigment), high reflective organic silicon composite material composition, etc.

[0063] In some embodiments, the etching rate of the material of the channel structure 111 is greater than the etching rate of the material of the first absorption layer 120 and the etching rate of the material of the avalanche layer 130. Here, the material of the channel structure 111 may be a germanium silicon material, such as SiGe; the material of the first absorption layer 120 and the avalanche layer 130 may be a Si substrate material.

[0064] In this disclosure, please continue to refer to Figure 4The first functional layer 110 is composed of a channel structure 111 and a first peripheral reflective structure 112; since the channel structure 111 is made of germanium silicon material, it has a faster etching rate than the Si-based first absorption layer 120 and avalanche layer 130. Therefore, when manufacturing a semiconductor device, a layer of germanium silicon material layer is first formed on the avalanche layer 130 through an epitaxial process, and then the first absorption layer 120 is formed on the germanium silicon material layer. Then, the channel structure 111 is etched out through the etching selectivity of the germanium silicon material and the silicon substrate material, so that the channel structure 111, the first absorption layer 120 and the avalanche layer 130 together form an "I-shaped" structure, and finally, the reflective material is further filled in the etched groove to form the first reflective structure 112. This "I-shaped" structure and formation process can not only form a channel for photogenerated carriers to pass through, but also make the first reflective structure 112 adjacent to the first absorption layer 120, so that the unabsorbed photons can be reflected to the first absorption layer 120 to be absorbed again, and the optical path difference between the photons absorbed by the second reflection and the photons absorbed at the first time is small, so that the photogenerated carriers generated in these two cases will not have a large time difference. In addition, the channel structure 111 formed by the epitaxial process and the etching process has fewer internal defects in the germanium silicon material, so the influence of the dark count rate caused by the internal defects of the channel structure 111 can be reduced.

[0065] In the disclosed embodiment, the first reflective structure 112 preferably uses an insulating material with high reflectivity, such as the above-mentioned metal oxide material, semiconductor material or organic material, etc. The insulating material with high reflectivity can not only reflect photons to improve quantum efficiency, but also prevent the free electrons inside the material from migrating to the avalanche layer 130 to interfere with photon detection. At this time, the semiconductor device has a single-photon level of sensitivity, that is, a single-photon avalanche diode (SPAD).

[0066] In some embodiments, please refer to Figure 5 , Figure 5Another optional structural schematic diagram of the semiconductor device 100 provided in the embodiment of the present disclosure. The first reflective structure 112 may also include a non-insulating material with high reflectivity, such as the above-mentioned metal material, alloy material, etc. In order to avoid interference of the non-insulating material's own electrons with photon detection, the first reflective structure 112 may include a structural support layer 112a and an insulating reflective layer 112b, and the insulating reflective layer 112b is located at the interface between the structural support layer 112a and the first absorption layer 120, the channel structure 111, and the avalanche layer 130. Among them, the structural support layer 112a may be a non-insulating material, and the insulating reflective layer 112b may be made of the above-mentioned insulating high-reflectivity material. In this way, the structural support layer 112a in the first reflective structure 112 can provide stable support for the above-mentioned "I-shaped" structure, and the insulating reflective layer 112b can reflect photons, and isolate the non-insulating structural support layer 112a from the first absorption layer 120, the channel structure 111 and the avalanche layer 130, so as to prevent the free electrons in the non-insulating structural support layer 112a from interfering with the photon detection, thereby achieving single-photon level sensitivity.

[0067] In the disclosed embodiment, on the one hand, since the first reflective structure 112 is adjacent to the first absorption layer 120, the optical path difference between the reflected photons and the direct photons is small, thereby improving the quantum efficiency of the semiconductor device while not affecting the consistency of the avalanche signal time. On the other hand, since the material of the channel structure 111 is germanium silicon material, the mobility of the photogenerated carriers can be improved and the recombination of the photogenerated carriers can be reduced.

[0068] In this disclosure, please continue to refer to Figures 3 to 5 , the material of the first absorption layer 120 can be selected according to the wavelength of the absorbed photons. For example, the material of the first absorption layer 120 can be silicon (Si); since the absorption spectrum of Si is mainly concentrated in the ultraviolet and visible light wavelength range (200-800nm), Si as the material of the first absorption layer 120 can show higher quantum efficiency and detection sensitivity in this range and have a lower dark count rate. In other embodiments, the material of the first absorption layer 120 can also be a germanium-tin (GeSn) alloy, which can be used to absorb short-wavelength ultraviolet light and light in the near-infrared region; or, the material of the first absorption layer 120 can be indium gallium arsenide (InGaAs), which can be used to absorb light of 0.9 to 1.7 microns (μm), and so on.

[0069] In addition, please continue to refer to Figures 3 to 5 The avalanche layer 130 includes a first doping region 131, a second doping region 132 and a semiconductor substrate 133 stacked in sequence from bottom to top along the Y-axis direction; wherein the doping types of the first doping region 131 and the second doping region 132 are opposite.

[0070] Specifically, the first doping region 131 may be a P-type doped (hole-rich) semiconductor material, and the second doping region 132 may be an N-type doped (electron-rich) semiconductor material; the semiconductor substrate 133 may be a P-type doped semiconductor material; wherein the P-type doped region is doped with trivalent impurity elements such as boron, gallium, and indium, and the N-type doped region is doped with pentavalent impurity elements such as phosphorus, antimony, and arsenic; the semiconductor material may be silicon (Si), germanium (Ge), and a compound semiconductor (such as gallium arsenide), etc. In this embodiment, the semiconductor substrate 133 is preferably a silicon (Si)-based substrate.

[0071] In the disclosed embodiment, the first doped region 131 and the second doped region 132 form a PN junction. The presence of the PN junction forms a high electric field region near the junction region, which is conducive to the separation and multiplication of photogenerated carriers. When the photogenerated carriers (electrons or holes) enter the avalanche layer 130, they are accelerated and gain energy in the high electric field region. When the energy of the carriers is high enough, they will collide with the lattice atoms in the semiconductor to generate additional electron-hole pairs. These newly generated carriers will continue to participate in the collision and multiplication process, thereby forming an avalanche multiplication effect, which can greatly amplify the number of photogenerated carriers and improve the sensitivity of the avalanche photodiode.

[0072] It should be noted that in other embodiments, the avalanche layer 130 may be other achievable structures, which are not limited here.

[0073] Next, combine Figures 6 to 8 The semiconductor device 100 provided by the embodiment of the present disclosure is described in detail.

[0074] In some embodiments, please refer to Figures 6 to 8 In the X-axis direction, the size of the channel structure 111 (as shown by D1 in the figure) is 1 / 10 to 1 / 3 of the size of the first functional layer 110 (as shown by D2 in the figure); in this way, the efficiency of the passage of photogenerated carriers can be ensured while the absorption efficiency of photons can also be guaranteed.

[0075] This is because: although a wider channel structure 111 (i.e., the dimension in the X-axis direction) can increase the passage efficiency of photogenerated carriers, an overly wide channel structure 111 may result in a smaller area between the first reflective structure 112 and the first absorption layer 120, so that unabsorbed photons cannot be reflected and absorbed again, thereby reducing the absorption efficiency of photons.

[0076] In some embodiments, please refer to Figures 6 to 8In the Y-axis direction, the size of the channel structure 111 (as shown by L1 in the figure) is 1 / 10 to 1 / 3 of the size of the semiconductor device 100 (as shown by L2 in the figure); in this way, the structural integrity and stability of the semiconductor device can be maintained while reducing the recombination of photogenerated carriers.

[0077] This is because: a thicker channel structure 111 will make the time for photogenerated carriers to pass longer, increase the probability of carrier recombination (i.e. disappearance), and cause greater loss of photogenerated carriers. If the thickness of the channel structure 111 is set to be thinner, it is difficult to control the etching process during its formation, and the channel structure 111 is easily completely etched to disappear, resulting in structural faults or film separation, causing failure of the semiconductor device.

[0078] Since the etching rate of the germanium silicon material is greater than that of silicon, during etching, the etching rate of the channel structure 111 (SiGe) is greater than the etching rates of the first absorption layer 120 (Si) and the avalanche layer 130 (Si); thus, a structure such as Figures 6 to 8 The structure shown, ie, the channel structure 111 , has a smaller dimension along the X-axis direction than the first absorption layer 120 and the avalanche layer 130 .

[0079] Furthermore, the molar concentration of the germanium element in the channel structure 111 may be between 15% and 25%. In some embodiments, the molar concentration of the germanium element in the channel structure 111 may be 15%, 18%, 20%, 22%, 25%, etc., preferably 20%, which will not be described in detail herein. When the molar concentration of the germanium element in the channel structure 111 is between 15% and 25%, a suitable etching selectivity ratio can be achieved between the germanium silicon material and the silicon substrate material. When the channel structure 111 is formed, the germanium silicon material layer and the silicon substrate material of the first absorption layer 120 and the avalanche layer 130 have a suitable relative etching rate, which is beneficial to the size control during the etching process.

[0080] It should be noted that the etching rates of the first absorption layer 120 and the avalanche layer 130 may be the same or different; for example, when the etching rate of the first absorption layer 120 is greater than the etching rate of the avalanche layer 130, the size of the first absorption layer 120 in the X-axis direction is smaller than the size of the avalanche layer 130 in the X-axis direction; conversely, when the etching rate of the first absorption layer 120 is less than the etching rate of the avalanche layer 130, the size of the first absorption layer 120 in the X-axis direction is larger than the size of the avalanche layer 130 in the X-axis direction.

[0081] In addition, since the material of the channel structure 111 is germanium silicon material and the material of the first absorption layer 120 is silicon, the mobility of electrons in germanium silicon material is greater than that of silicon, so the mobility of photogenerated carriers in the channel structure 111 is higher than that in the first absorption layer 120.

[0082] In this way, the photogenerated carriers can move to the channel structure 111 faster, reducing the movement time of the photogenerated carriers and making the response speed of the semiconductor device higher; further, due to the high mobility in the channel structure 111, the residence time of the photogenerated carriers is reduced, thereby reducing the recombination rate of the photogenerated carriers and improving the quantum efficiency of the semiconductor device.

[0083] In some embodiments, please refer to Figures 6 to 8 The semiconductor device 100 further includes a first metal pin 151 and a second metal pin 152 . The first metal pin 151 is connected to the first doping region 131 , and the second metal pin 152 is connected to the second doping region 132 .

[0084] Here, the material of the first metal pin 151 and the second metal pin 152 can be any suitable conductive material, such as tungsten (W), cobalt (Co), copper (Cu), aluminum (Al), etc.

[0085] Furthermore, when the first doping region 131 and the second doping region 132 are P-type doped and N-type doped, respectively, the first metal pin 151 and the second metal pin 152 are connected to the anode and cathode of the power supply, respectively, so that the bias voltage can be provided through the first metal pin 151 and the second metal pin 152, so that under the condition of reverse bias voltage (i.e., high voltage is applied to the cathode and the anode is grounded), the PN junction formed by the first doping region 131 and the second doping region 132 is in a reverse working state. When photons are absorbed in the depletion region, a carrier multiplication effect is generated, which instantly reduces the reverse resistance of the PN junction, thereby generating a very high reverse current.

[0086] In some embodiments, please refer to Figure 8 The semiconductor device 100 further includes: a second absorption layer 141 located on a side of the first absorption layer 120 away from the first functional layer 110 , and a second reflection structure 142 located at the periphery of the second absorption layer 141 .

[0087] Here, the material of the second reflective structure 142 may be the same as that of the first reflective structure 112. The material of the second absorption layer 141 may be a germanium silicon material (e.g., SiGe), and the concentration of germanium in the material of the second absorption layer 141 is less than the concentration of germanium in the material of the channel structure 111; specifically, the concentration of germanium in the material of the second absorption layer 141 is 5% to 10%. Since the concentration of germanium in the material of the second absorption layer 141 is less than the concentration of germanium in the material of the channel structure 111, the etching rate of the second absorption layer 141 is less than the etching rate of the channel structure 111.

[0088] Thus, on the one hand, since the germanium silicon material has a high absorption rate of photons, the absorption rate of photons by the semiconductor device 100 can be improved. On the other hand, since the concentration of germanium in the second absorption layer 141 is relatively high at 5% to 10%, the etching rate of the second absorption layer 141 can be made lower than the etching rate of the channel structure 111 during etching, so that the size of the second absorption layer 141 along the X-axis direction is larger (e.g. Figure 8 As shown), this not only increases the incident area of ​​photons, but also ensures the absorption rate of photons.

[0089] In some embodiments, please refer to Figures 6 to 8 The semiconductor device 100 further includes a refractive microstructure 160. For details, please continue to refer to Figure 6 and Figure 7 The refractive microstructure 160 is located on the side of the first absorption layer 120 away from the first functional layer 110; the refractive microstructure 160 is used to converge photons to the first absorption layer 120. Alternatively, please refer to Figure 8 The refractive microstructure 160 is located on a side of the second absorption layer 141 away from the first functional layer 110 ; the refractive microstructure 160 is used to converge photons to the second absorption layer 141 .

[0090] Here, the refractive microstructure 160 may be an inverted pyramid microlens array, and the material of the refractive microstructure 160 may be fused quartz or other transparent medium. These microlenses are formed on the surface of the first absorption layer 120 or the second absorption layer 141 by flipping, and the incident light is concentrated into the first absorption layer 120 or the second absorption layer 141 by using the principle of refraction or diffraction, thereby improving the photon detection efficiency and making the performance of the semiconductor device better.

[0091] In this disclosure, please continue to refer to Figures 6 to 8 The semiconductor device 100 further includes: a third reflective structure 170 and an isolation structure 180 located on the sidewall of the third reflective structure 170. Figure 6 , the third reflective structure 170 is located on the sidewalls of the first functional layer 110, the first absorption layer 120 and the avalanche layer 130. Alternatively, please continue to refer to Figure 8 The third reflective structure 170 is located on the sidewalls of the first functional layer 110 , the first absorption layer 120 , the avalanche layer 130 and the second reflective structure 142 .

[0092] In the embodiments of the present disclosure, see Figure 6 The third reflective structure 170 can be made of the same material as the first reflective structure 112. The first reflective structure 112 and the third reflective structure 170 can be integrally formed. For example, the first reflective structure 112 and the third reflective structure 170 can be formed in one process by an atomic deposition process. Figure 7 Since the first reflective structure 112 may include a structural support layer 112a and an insulating reflective layer 112b, due to process reasons (such as atomic deposition process), the insulating reflective layer 112b will extend to the side walls of the first absorption layer 120 and the avalanche layer 130, so that the third reflective structure 170 can be located on the first functional layer 110 and along the side walls of the extended insulating reflective layer 112b.

[0093] Here, the material of the isolation structure 180 can be any insulating material, such as silicon oxide or silicon oxynitride. The third reflective structure 170 can reflect the photons that converge on the side wall of the first absorption layer 120 to increase the absorption efficiency of the photons; the isolation structure 180 can be used to isolate adjacent semiconductor devices, reduce the generation of leakage current, and improve the stability of semiconductor devices.

[0094] In the embodiment of the present disclosure, on the one hand, since the first reflective structure 112 is disposed at the periphery of the channel structure 111, the first reflective structure 112 is adjacent to the first absorption layer 120, so that the photons that are not absorbed can be absorbed again after being reflected; since there is no significant time difference between the photons absorbed for the second time and the photons absorbed for the first time, the quantum efficiency of the semiconductor device 100 is improved without affecting the time consistency of the avalanche signal. On the other hand, the mobility of the photogenerated carriers in the channel structure 111 is higher than that in the first absorption layer 120, reducing carrier recombination, and the photogenerated carriers can directly reach the avalanche layer 130 after passing through the channel structure 111, reducing the loss of photogenerated carriers.

[0095] The present disclosure also provides a method for forming the semiconductor device 100. Fig. 9 A schematic diagram of a process for forming a semiconductor device provided by an embodiment of the present disclosure, Figures 10a to 10d A schematic structural diagram of a semiconductor device 100 during a formation process provided by an embodiment of the present disclosure.

[0096] In the embodiments of the present disclosure, please refer to Fig. 9 , the method for forming the semiconductor device 100 includes: step S110 to step S130.

[0097] S110: providing an initial stacking structure, the initial stacking structure comprising a first initial functional layer, and a first initial absorption layer and an initial avalanche layer respectively located on a top surface and a bottom surface of the first initial functional layer;

[0098] S120: etching the initial stacking structure to form an etched structure; the etched structure includes a channel structure formed after etching the first initial functional layer, a first etched groove around the channel structure, a first absorption layer formed after etching the first initial absorption layer, and an avalanche layer formed after etching the initial avalanche layer;

[0099] S130: Filling the etched structure to form a semiconductor device; the semiconductor device includes a first absorption layer, a first functional layer and an avalanche layer, the first functional layer includes a channel structure and a first reflective structure with a first etched groove filled around the channel structure.

[0100] The method is described below with reference to the accompanying drawings and specific embodiments:

[0101] First, refer to Fig. 9 , Figures 10a to 10c , executing step S110, providing an initial stacking structure 100a, such as Fig.10c The initial stacking structure 100a includes a first initial functional layer 110a and a first initial absorption layer 120a and an initial avalanche layer 130a respectively located on the top surface and the bottom surface of the first initial functional layer 110a.

[0102] The initial avalanche layer 130a can be manufactured by the following process flow. Fig.10a and Fig.10b First, an initial semiconductor substrate 133a is provided, such as Fig.10a As shown. The initial semiconductor substrate 133a can be a P-type doped semiconductor material, for example, P-type doped silicon, germanium, and compound semiconductors (such as gallium arsenide); next, the initial semiconductor substrate 133a is sequentially N-type doped and P-type doped to form a second doping region 132 and a first doping region 131. Finally, the initial semiconductor substrate 133a can be thinned from the back side (i.e., the surface away from the first doping region 131) by chemical mechanical polishing (CMP) to form an intermediate semiconductor substrate 133b, as shown. Fig.10b The first doping region 131, the second doping region 132 and the intermediate semiconductor substrate 133b constitute an initial avalanche layer 130a.

[0103] The first initial functional layer 110a and the first initial absorption layer 120a can be manufactured by the following process flow. Fig.10c , a first initial functional layer 110a and a first initial absorption layer 120a are sequentially formed on the back side of the intermediate semiconductor substrate 133b (i.e., the surface away from the first doping region 131). Here, the material of the first initial functional layer 110a is germanium silicon material, such as SiGe, and the material of the first initial absorption layer 120a is silicon.

[0104] In the embodiment of the present disclosure, the first initial functional layer 110a can be formed by an epitaxial process, so that defects in the first initial functional layer 110a can be reduced, so that the channel structure 111 in the subsequently generated semiconductor device 100 has a lower dark count rate. The first initial absorption layer 120a can be formed by any of the following deposition processes: epitaxial process, chemical vapor deposition (Chemical Vapor Deposition, CVD) process, physical vapor deposition (Physical Vapor Deposition, PVD) process, atomic layer deposition (Atomic Layer Deposition, ALD) process, spin coating process, coating process or thin film process, etc.

[0105] Next, refer to Fig. 9 and Fig.10d , executing step S120, etching the initial stacked structure 100a to form an etched structure 100b, such as Fig.10d The etched structure 100b includes a channel structure 111 formed by etching the first initial functional layer 110a, a first etched groove 111a around the channel structure 111, a first absorption layer 120 formed by etching the first initial absorption layer 120a, and an avalanche layer 130 formed by etching the initial avalanche layer 130a.

[0106] During implementation, the initial stacked structure 100a can be etched by a wet etching process. Since the materials of the intermediate semiconductor substrate 133b and the first initial absorption layer 120a are silicon, and the material of the first initial functional layer 110a is germanium silicon material, the etching speed of the first initial functional layer 110a is greater than that of the intermediate semiconductor substrate 133b and the first initial absorption layer 120a. When the concentration of the etching solution and the concentration of the germanium element in the germanium silicon material remain unchanged, the size of the channel structure 111 along the X-axis direction is controlled by controlling the etching time, thereby forming a channel structure 111 as shown in FIG. Fig.10d In other embodiments, the first initial functional layer 110a may be etched by any other suitable etching method, which is not limited in the present disclosure.

[0107] Please continue to refer to Fig.10d Since the entire initial stacked structure 100a is etched synchronously when the initial stacked structure 100a is etched by the wet etching process, the formed etched structure 100b is reduced in overall size compared to the initial stacked structure 100a, and the reduced portion is shown by the dotted line.

[0108] Finally, reference Fig. 9 and Figure 6, execute step S130, fill the etched structure 100b to form a semiconductor device 100; the semiconductor device 100 includes a first absorption layer 120, a first functional layer 110 and an avalanche layer 130, the first functional layer 110 includes a channel structure 111 and a first reflective structure 112 that fills a first etched groove around the channel structure 111.

[0109] When implementing, please refer to Figure 6 , the first reflective structure 112 located at the periphery of the channel structure 111 can be formed in the first etched groove 111a by any suitable deposition process. For example, a chemical vapor deposition process (Chemical Vapor Deposition), a physical vapor deposition (Physical Vapor Deposition, PVD) process, an atomic layer deposition (Atomic Layer Deposition, ALD) process, a spin coating process, a coating process or a furnace process. Here, the first reflective structure 112 can be any suitable insulating or non-insulating high reflectivity material.

[0110] In some other embodiments, forming Figure 7 In the semiconductor device 100 shown, an insulating reflective layer 112b and a structural support layer 112a may be sequentially formed in the first etched groove 111a by any suitable deposition process. Here, the structural support layer 112a may be any suitable non-insulating material, and the insulating reflective layer 112b may be any suitable insulating high-reflectivity material.

[0111] For further information, please refer to Figure 6 When the first reflective structure 112 is formed, a third reflective structure 170 located on the side walls of the first functional layer 110 , the first absorption layer 120 , and the avalanche layer 130 may also be formed.

[0112] In this disclosure, please continue to refer to Figure 6 After forming the first reflective structure 112 and the third reflective structure 170 , the method for forming a semiconductor device further includes: forming an isolation structure 180 on a surface of a sidewall of the third reflective structure 170 by any suitable deposition process.

[0113] In this disclosure, please continue to refer to Figure 6 After forming the isolation structure 180, the method for forming the semiconductor device 100 also includes: forming a first metal pin 151 connected to the first doping region 131, and a second metal pin 152 connected to the second doping region 132; and a refractive microstructure 160 located on the side of the first absorption layer 120 away from the first functional layer 110.

[0114] In the embodiment of the present disclosure, by utilizing the difference in etching rates between silicon and silicon germanium materials, when etching the etching structure 100b, the etching rate of the first initial functional layer 110a is made greater than that of the first initial absorption layer 120a and the initial avalanche layer 130a along the X-axis direction; in this way, the channel structure 111 formed after etching the first initial functional layer 110a can have a first etched groove 111a on the periphery, and further a first reflective structure 112 can be formed on the periphery of the channel structure 111.

[0115] Thus, through the method for forming a semiconductor device in the embodiment of the present disclosure, the formed semiconductor device has the following effects: First, since the unabsorbed photons can be absorbed again after being reflected by the first reflective structure 112, and the optical path difference between the reflected photons and the direct photons is small, the quantum efficiency of the semiconductor device is improved while the consistency of the avalanche signal time is not affected. Second, since the material of the channel structure 111 is germanium silicon material, the mobility of the photogenerated carriers is improved and the recombination of the photogenerated carriers is reduced.

[0116] The present disclosure also provides a method for forming the semiconductor device 100. Fig.11 A schematic diagram of a process flow of another method for forming a semiconductor device provided in an embodiment of the present disclosure, Fig.12a and Figure 12b A schematic structural diagram of another semiconductor device 100 during the formation process provided by an embodiment of the present disclosure.

[0117] In the embodiment of the present disclosure, the method for forming the semiconductor device 100 includes: step S210 to step S230.

[0118] S210: providing an initial stacking structure, the initial stacking structure comprising an initial avalanche layer, a first initial functional layer, a first initial absorption layer, a second initial absorption layer and a sacrificial layer stacked in sequence along the Y-axis direction;

[0119] S220: etching the initial stacked structure to form an etched structure; the etched structure includes an avalanche layer, a channel structure, a first absorption layer, a second absorption layer and a sacrificial layer stacked in sequence along the Y-axis direction;

[0120] S230: Filling the etched structure to form a semiconductor device; the semiconductor device includes a first absorption layer, a first functional layer, an avalanche layer, and a second functional layer; the first functional layer includes a channel structure and a first reflective structure filling the first etched groove around the channel structure, and the second functional layer includes a second absorption layer and a second reflective structure around the second absorption layer.

[0121] First, refer to Fig.12a and Figure 12b, perform step S210 to provide an initial stacking structure 100a, the initial stacking structure 100a includes an initial avalanche layer 130a, a first initial functional layer 110a, a first initial absorption layer 120a, a second initial absorption layer 141a and a sacrificial layer 190 stacked in sequence along the Y-axis direction.

[0122] Here, the formation method of the initial avalanche layer 130a is understood by referring to the above embodiment, and will not be described here. After the initial avalanche layer 130a is formed, the first initial functional layer 110a, the first initial absorption layer 120a, the second initial absorption layer 141a and the sacrificial layer 190 are sequentially generated on the back side of the initial avalanche layer 130a (i.e., the surface away from the first doping region 131).

[0123] Here, the material of the second initial absorption layer 141a is a germanium silicon material (e.g., SiGe), wherein the concentration of the germanium element is 5% to 10%. The material of the sacrificial layer 190 can be one or any combination of silicon nitride (SiN), silicon oxynitride (SiON), amorphous carbon (aC), or silicon oxycarbonitride (SiOCN).

[0124] In the embodiment of the present disclosure, the first initial functional layer 110a and the second initial absorption layer 141a can be formed by an epitaxial process, so that defects in the first initial functional layer 110a and the second initial absorption layer 141a can be reduced, so that the channel structure 111 in the subsequently generated semiconductor device 100 has a lower dark count rate, thereby improving the performance of the semiconductor device 100. The first initial absorption layer 120a and the sacrificial layer 190 can be formed by any suitable process.

[0125] Next, refer to Fig.11 and Figure 12b , execute step S220, etch the initial stacked structure 100a to form an etched structure 100b; the etched structure 100b includes an avalanche layer 130, a channel structure 111, a first absorption layer 120, a second absorption layer 141 and a sacrificial layer 190 stacked in sequence along the Y-axis direction.

[0126] Specifically, the avalanche layer 130 is formed after etching the initial avalanche layer 130a, the channel structure 111 is formed after etching the first initial functional layer 110a, and the first etched groove 111a around the channel structure 111 is formed, the first absorption layer 120 is formed after etching the first initial absorption layer 120a, the second absorption layer 141 is formed after etching the second initial absorption layer 141a, and the second etched groove 140a around the second absorption layer 141 is formed, and the etched sacrificial layer 190. The sacrificial layer 190 is used to prevent damage to the upper surface of the second absorption layer 141 during the etching process.

[0127] In this way, during etching, the etching rate of the second absorption layer 141 can be made lower than the etching rate of the channel structure 111, so that the size of the second absorption layer 141 along the X-axis direction is larger (eg Figure 12b As shown), this not only increases the incident area of ​​photons, but also ensures the absorption rate of photons.

[0128] Finally, reference Fig.11 and Figure 8 , execute step S230, fill the etched structure 100b to form a semiconductor device 100; the semiconductor device 100 includes a first absorption layer 120, a first functional layer 110, an avalanche layer 130 and a second absorption layer 141; the first functional layer 110 includes a channel structure 111 and a first reflective structure 112 that fills a first etched groove 111a around the channel structure 111.

[0129] In the embodiments of this disclosure, please refer to Figure 8 , the semiconductor device 100 further includes a second reflective structure 142 located at the periphery of the second absorption layer 141. During implementation, the first reflective structure 112 located at the periphery of the channel structure 111 can be formed in the first etched groove 111a by any suitable deposition process, and the second reflective structure 142 located at the periphery of the second absorption layer 141 can be formed in the second etched groove 140a. Here, the first reflective structure 112 and the second reflective structure 142 can be any insulating or non-insulating material with high reflectivity.

[0130] For further information, please refer to Figure 8 , while forming the first reflective structure 112 and the second reflective structure 142, a third reflective structure 170 is formed on the sidewalls of the first functional layer 110, the first absorption layer 120, the avalanche layer 130 and the second reflective structure 142. In this embodiment, the first reflective structure 112, the second reflective structure 142 and the third reflective structure 170 can be made of the same material and are integrally formed.

[0131] In this disclosure, please continue to refer to Figure 8 After forming the first reflective structure 112 , the second reflective structure 142 and the third reflective structure 170 , the method for forming a semiconductor device further includes: forming an isolation structure 180 on a surface of a sidewall of the third reflective structure 170 by any suitable deposition process.

[0132] In this disclosure, please continue to refer to Figure 8 After forming the isolation structure 180, the method for forming the semiconductor device 100 further includes: removing the surface sacrificial layer 190, so that the second absorption layer 141 is located on the surface of the semiconductor device 100. In the embodiment of the present disclosure, the sacrificial layer 190 can be removed by any suitable process, for example, by chemical mechanical polishing.

[0133] In this disclosure, please continue to refer to Figure 8 After removing the sacrificial layer 190 , the method for forming the semiconductor device 100 further includes: forming a first metal pin 151 connected to the first doping region 131 , a second metal pin 152 connected to the second doping region 132 ; and a refractive microstructure 160 located on a side of the first absorption layer 120 away from the first functional layer 110 .

[0134] Through the method for forming a semiconductor device in the embodiment of the present disclosure, the semiconductor device formed has a high absorption rate of photons by the germanium silicon material, thereby improving the absorption rate of photons by the semiconductor device 100. In addition, since the first functional layer is arranged between the absorption layer and the avalanche layer, the first functional layer can reflect the photons that are not absorbed by the first absorption layer back to the first absorption layer, and the first functional layer is adjacent to the first absorption layer, so that the optical path difference between the photons absorbed by the second reflection and the photons absorbed at the first time is small, so that the photogenerated carriers generated in these two cases will not have a large time difference, thereby ensuring the time consistency of the avalanche signal and achieving a better imaging effect.

[0135] It should be noted that the embodiment of the present disclosure is formed by Figure 6 and Figure 8 The semiconductor device 100 shown is taken as an example for explanation. The formation process of semiconductor devices 100 with other structures can be understood by referring to the above embodiments, and will not be described in detail here.

[0136] The semiconductor device formed by the method for forming a semiconductor device provided in the embodiment of the present disclosure is similar to the semiconductor device in the above-mentioned embodiment. For the technical features not fully disclosed in the embodiment of the present disclosure, please refer to the above-mentioned embodiment for understanding, and no further details will be given here.

[0137] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the protection scope of the present disclosure.

[0138] It should be noted that in the present disclosure, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0139] The serial numbers of the above-mentioned embodiments of the present disclosure are only for description and do not represent the advantages or disadvantages of the embodiments.

[0140] The methods disclosed in several method embodiments provided in the present disclosure can be arbitrarily combined without conflict to obtain new method embodiments.

[0141] The features disclosed in several product embodiments provided in the present disclosure can be arbitrarily combined without conflict to obtain new product embodiments.

[0142] The features disclosed in several method or device embodiments provided in the present disclosure may be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0143] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A semiconductor device, characterized in that: include: a first functional layer, and a first absorption layer and an avalanche layer respectively located on the top and bottom surfaces of the first functional layer; The first absorption layer is used to absorb photons and generate photogenerated carriers; The first functional layer is configured to reflect photons not absorbed by the first absorption layer back to the first absorption layer, and to transmit photogenerated carriers generated by the first absorption layer to the avalanche layer; The avalanche layer is used to cause the photogenerated carriers entering therein to trigger an avalanche effect and generate an avalanche current.

2. The semiconductor device according to claim 1, wherein The first functional layer includes a channel structure and a first reflective structure located outside the channel structure; The channel structure is used to transfer carriers generated by the first absorption layer to the avalanche layer; The first reflective structure is used to reflect photons that are not absorbed by the first absorption layer.

3. The semiconductor device according to claim 2, wherein: The etching rate of the material of the channel structure is greater than the etching rate of the material of the first absorption layer and the etching rate of the material of the avalanche layer.

4. The semiconductor device according to claim 2, wherein The mobility of photogenerated carriers in the channel structure is higher than that in the first absorption layer.

5. The semiconductor device according to claim 2, wherein The first reflective structure includes a structural support layer and an insulating reflective layer. The insulating reflective layer is located at the interface between the structural support layer, the first absorption layer, the channel structure, and the avalanche layer.

6. The semiconductor device according to any one of claims 2 to 5, characterized in that In the first direction, the size of the channel structure is 1 / 10 to 1 / 3 of the size of the first functional layer; In the second direction, the size of the channel structure is 1 / 10 to 1 / 3 of the size of the semiconductor device; The first direction is parallel to the plane where the first functional layer is located; and the second direction is perpendicular to the plane where the first functional layer is located.

7. The semiconductor device according to claim 6, wherein: Also includes: a second absorption layer located on a side of the first absorption layer away from the first functional layer; The material composition of the second absorption layer is the same as that of the channel structure.

8. The semiconductor device according to claim 7, wherein: The etching rate of the material of the channel structure is greater than the etching rate of the material of the second absorption layer.

9. The semiconductor device according to claim 7 or 8, characterized in that The second absorption layer and the channel structure are made of germanium silicon material. The concentration of germanium in the second absorption layer is lower than the concentration of germanium in the channel structure.

10. A method for forming a semiconductor device, characterized in that: The method comprises: Providing an initial stacking structure, the initial stacking structure comprising a first initial functional layer, and a first initial absorption layer and an initial avalanche layer respectively located on the top surface and the bottom surface of the first initial functional layer; Etching the initial stacked structure to form an etched structure; the etched structure includes a channel structure formed after etching the first initial functional layer, a first etched groove around the channel structure, a first absorption layer formed after etching the first initial absorption layer, and an avalanche layer formed after etching the initial avalanche layer; The etched structure is filled to form the semiconductor device; the semiconductor device includes a first absorption layer, a first functional layer and an avalanche layer, the first functional layer includes the channel structure and a first reflective structure filling the first etched groove around the channel structure.

11. The method according to claim 10, characterized in that The initial stacked structure further includes a second initial absorption layer and a surface sacrificial layer located on a side of the first initial absorption layer away from the first initial functional layer, and the method further includes: When etching the initial stack structure to form an etched structure, the second initial absorption layer and the surface sacrificial layer are simultaneously etched to form a second absorption layer and a second etched groove around the second absorption layer; After forming the second absorption layer, the surface sacrificial layer is removed, so that the second absorption layer is located on the surface of the semiconductor device.

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