HBT device

Abstract

The invention provides an HBT device. The HBT device comprises a collector structure; the collector electrode structure comprises a secondary collector electrode layer, a collector electrode layer arranged above the secondary collector electrode layer, and collector electrode contact metal; the collector contact metal is in contact with the secondary collector layer, and a contact surface between the collector contact metal and the secondary collector layer at least comprises a first contact part and a second contact part which are connected with each other; wherein the first contact part is parallel to the upper surface, where the collector layer is arranged, in the secondary collector layer, and a set angle is formed between the second contact part and the first contact part.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to an HBT device. Background Technology

[0002] In the design of heterojunction bipolar transistors (HBTs), a low collector resistance (Rc) is a crucial reference indicator for the device's radio frequency (RF) performance. A lower internal Rc reduces additional power losses in the RF device, thereby improving the overall power efficiency. The Rc resistance is primarily affected by the epitaxial layer's own resistance, the contact resistance between the epitaxial layer and the collector metal, and the resistance of the external interconnect metal. Typically, under certain electrical performance requirements, the epitaxial doping concentration and thickness are relatively fixed, and the external interconnect metal is also generally consistent in the fabrication process. Therefore, reducing the contact resistance between the epitaxial layer and the metal, and thus reducing the overall Rc resistance, is extremely important for improving the device's RF performance. Summary of the Invention

[0003] To address the existing technical problems, this application provides an HBT device that can reduce the contact resistance between the epitaxial layer and the collector metal.

[0004] This application provides an HBT device, including: a collector structure; the collector structure includes a secondary collector layer, a collector layer disposed above the secondary collector layer, and a collector contact metal; the collector contact metal contacts the secondary collector layer, and the contact surface between the collector contact metal and the secondary collector layer includes at least a first contact portion and a second contact portion connected to each other; wherein, the first contact portion is parallel to the upper surface of the collector layer disposed in the secondary collector layer, and the second contact portion forms a predetermined angle with respect to the first contact portion.

[0005] Compared with the prior art, the technical solution provided in this application has at least the following beneficial effects: In the HBT device provided in the above embodiments, the collector contact metal contacts the secondary collector layer, and the contact surface between the collector contact metal and the secondary collector layer includes at least a first contact portion and a second contact portion. The first contact portion is parallel to the upper surface of the secondary collector layer where the collector layer is disposed, and the second contact portion forms a predetermined angle with respect to the first contact portion. Thus, compared to a method where only a horizontal contact surface covers the upper surface of the secondary collector layer, the collector contact metal adds a contact portion with the secondary collector layer that is different from the horizontal direction, thereby forming a structure that forms a contact surface with the secondary collector layer in different directions. The second contact portion, based on a contact surface different from the horizontal direction, can form a larger contact area with the secondary collector layer without resulting in a larger coverage area in the horizontal direction of the upper surface. This avoids excessive surface area occupation and, based on the negative correlation between contact resistance and contact area, generates a larger contact area, reducing the contact resistance between the collector metal and the secondary collector layer, thereby improving the performance of the HBT device. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the structure of an HBT device in related technologies; Figure 2 This is a schematic diagram of the structure of an HBT device in one embodiment of this application; Figure 3 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 4 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 5 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 6 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 7 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 8 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 9 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 10 This is a schematic diagram of the structure of an HBT device in another embodiment of this application; Figure 11 This is a schematic diagram of the structure of an HBT device in another embodiment of this application.

[0007] Explanation of reference numerals in the attached figures 1. Substrate; 2. Secondary collector layer; 21. First surface; 22. Second surface; 23. Step structure; 3. Collector layer; 4. Collector contact metal; 41. First portion; 42. Second portion; 43. Third portion; 44. Fourth portion; 45. Fifth portion; 5. Low bandgap semiconductor material layer; 61. Buffer layer; 62. Etching stop layer; 63. Base layer; 64. Emitter layer; 65. Emitter cap layer; 66. Base contact metal; 67. Emitter ohmic contact layer; 68. Emitter contact metal; 69. Isolation region. Detailed Implementation

[0008] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0009] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description of this application will be provided in conjunction with the accompanying drawings. The described embodiments should not be considered as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0010] In the following description, the phrase "some embodiments" refers to a subset of all possible embodiments. It should be noted that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0011] In the following description, the terms "first," "second," and "third" are used merely to distinguish similar objects and do not represent a specific ordering of the objects. It is understood that "first," "second," and "third" can be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0012] In the process of researching HBT transistor devices, the inventors of this application conducted the following research on the collector contact resistance problem in HBT devices: In one embodiment, such as Figure 1The diagram shows a cross-sectional view of a conventional HBT device structure. It mainly includes a substrate 1 made of a III-V group semiconductor material, such as GaAs, AlGaAs, SiC, GaN, AlGaN, AlN, InP, InAlAs, InGaAs, or Si; a buffer layer 61 made of at least one of AlGaAs, AlAs, or InGaP; a secondary collector layer 2 made of N+ GaAs; an etch stop layer 62 made of N+ InGaP; a collector layer 3 made of N or N- GaAs; a base layer 63 made of P+ type GaAs, InGaAs, or GaAsSb; an emitter layer 64 made of N or N-InGaP; an emitter cap layer 65 made of N+ or N GaAs (N+ GaAs); and an emitter ohmic contact layer 67 made of N+ InGaAs. Emitter steps are formed by etching the emitter ohmic contact layer 67 and the emitter cap layer 65, and base steps are formed by etching the emitter layer 64, the base layer 63, and the collector layer 3. An emitter contact metal 68 is provided on the emitter ohmic contact layer 67; a base contact metal 66 is provided on the base layer 63; and a collector contact metal 4 is provided on the secondary collector layer 2. An isolation region 69 is formed in the secondary collector layer 2 away from the base steps through ion implantation.

[0013] In the embodiments Figure 1 In this process, the collector contact metal 4 is directly vapor-deposited onto the plane of the epitaxial secondary collector layer 2 to form an ohmic contact. The contact resistance is affected by the contact area between the collector contact metal 4 and the secondary collector layer 2. With a fixed photomask layout and process, the contact area between the fabricated collector contact metal and the secondary collector layer is also fixed. Therefore, the only way to reduce the overall collector resistance Rc and improve device performance is to decrease the distance from the collector contact metal to the base step. For example, Rc can be reduced by designing the collector contact metal to partially cross the base step. However, directly crossing the base step with the collector contact metal carries certain process risks and requires strict epitaxial design; otherwise, the base-collector breakdown voltage will decrease, affecting device applications.

[0014] In view of this, one embodiment of this application provides an HBT device, which may include: a substrate 1 and a collector structure disposed on the substrate 1; the collector structure includes a secondary collector layer 2, a collector layer 3 disposed above the secondary collector layer 2, and a collector contact metal 4; The current collector contact metal 4 is in contact with the secondary current collector layer 2, and the contact surface between the current collector contact metal 4 and the secondary current collector layer 2 includes at least a first contact portion and a second contact portion that are connected to each other. The first contact portion is parallel to the upper surface of the collector layer in the secondary collector layer 2, and the second contact portion is at a predetermined angle relative to the first contact portion.

[0015] In one embodiment, the secondary collector layer 2 is disposed on the substrate 1. The first contact portion is parallel to the upper surface, and the projected area of ​​the second contact portion in a first direction is greater than 0; the first direction is a direction perpendicular to the upper surface; the upper surface is the upper surface of the secondary collector layer 2 away from or opposite to the substrate 1.

[0016] In one embodiment, the set angle is the angle between the second contact portion and the first contact portion, for example, it refers to the angle between the second contact portion and the first contact portion on a cross section along a first direction. The first direction is as follows: Figure 2 The AA direction shown refers to a direction perpendicular to the upper surface of the secondary collector layer 2 and parallel to the arrangement direction of the collector contact metal 4 and the collector layer 3. The set angle is a non-zero angle, meaning the second contact portion is not parallel to the upper surface of the secondary collector layer 2. For example, the set angle could be 90 degrees, etc.

[0017] It should be noted that the structural schematic diagrams in the embodiments of this application are all cross-sectional schematic diagrams along the first direction.

[0018] In one embodiment, such as Figure 2 The cross-sectional view of the HBT device structure shown includes a substrate 1, a buffer layer 61, a secondary collector layer 2, an etch stop layer 62, a collector layer 3, a base layer 63, an emitter layer 64, an emitter cap layer 65, and an emitter ohmic contact layer 67. Emitter steps are formed by etching the emitter ohmic contact layer 67 and the emitter cap layer 65; base steps are formed by etching the emitter layer 64, the base layer 63, and the collector layer 3; and a secondary collector groove is formed by etching the secondary collector 2. An emitter contact metal 68 is provided on the emitter ohmic contact layer 67; a base contact metal 66 is provided on the base layer 63; and a collector contact metal 4 (including at least a first portion 41 and a second portion 42) is provided on the secondary collector layer 2. An isolation region 69 is formed in the region of the secondary collector layer 2 away from the base steps by ion implantation.

[0019] The current collector contact metal 4 includes a first portion 41 protruding outside the groove and a second portion 42 filling the groove; the contact surface between the first portion 41 and the upper surface of the secondary current collector layer 2 is the first contact portion, and the contact surface between the side surface of the second portion 42 and the secondary current collector layer 2 is the second contact portion. Here, the side surface refers to a surface that is not parallel to the upper surface of the secondary current collector layer 2.

[0020] In one embodiment, the collector contact metal 4 includes: a first part 41 and a second part 42 in contact; the first part 41 covers the upper surface of the secondary collector layer 2, and the second part 42 is inserted into the secondary collector layer 2 through a groove. The first part 41 and the second part 42 form a T-shaped structure, that is, the second part 42 is inserted into the secondary collector layer 2 along the first direction.

[0021] In one embodiment, the first portion 41 of the current collector contact metal 4 has a distance ≥0.1 μm between its edge and the base step in a cross-section along the first direction. Here, the edge of the first portion 41 refers to the edge close to the current collector layer 3, and the distance between it and the base step is the minimum distance between the current collector layer 3 and the edge of the current collector layer 3.

[0022] In one embodiment, in a cross section along the first direction, the distance between the edge of the second portion 42 on one side and the edge of the first portion 41 on the same side is ≥0.1μm. Here, the edge of the second portion 42 on one side is the edge that forms a second contact portion with the secondary collector layer 2. One side refers to the side closer to the collector layer 3 and / or the side farther away from the collector layer 3.

[0023] The depth of the groove into which the second portion 42 of the collector contact metal 4 is inserted is less than the thickness of the secondary collector layer 2. For example, the depth of the groove is 0.3 μm to 0.6 μm, and the depth is the depth along the first direction. Thus, a reasonable setting of the groove depth can avoid insufficient contact area between the collector contact metal 4 and the secondary collector layer 2 due to an excessively shallow groove, and can also avoid the possibility of the groove being too deep and penetrating the secondary collector layer 2.

[0024] By using the contact surface between the first contact portion (i.e., the first part 41) and the upper surface of the secondary collector layer 2, the contact surface between the side of the second contact portion (i.e., the second part 42) and the secondary collector layer 2, and the contact surface between the bottom surface of the second part 42 formed by inserting into the secondary collector layer 2 and the secondary collector layer 2, the contact area between the collector contact metal 4 and the secondary collector layer 2 can be increased, thereby reducing the resistance of the collector contact metal 4 and improving the RF performance of the device.

[0025] In one embodiment, such as Figure 3The cross-sectional view of the HBT device structure shown includes a substrate 1, a buffer layer 61, a secondary collector layer 2, an etch stop layer 62, a collector layer 3, a base layer 63, an emitter layer 64, an emitter cap layer 65, and an emitter ohmic contact layer 67. Emitter steps are formed by etching the emitter ohmic contact layer 67 and the emitter cap layer 65; base steps are formed by etching the emitter layer 64, the base layer 63, and the collector layer 3; and a secondary collector groove is formed by etching the secondary collector 2. An emitter contact metal 68 is provided on the emitter ohmic contact layer 67; a base contact metal 66 is provided on the base layer 63; and a collector contact metal 4 (including at least a first portion 41 and a second portion 42) is provided on the secondary collector layer 2. An isolation region 69 is formed in the region of the secondary collector layer 2 away from the base steps by ion implantation.

[0026] The groove in the secondary collector layer 2 has a trapezoidal cross-sectional shape in the direction perpendicular to the upper surface of the secondary collector layer 2, i.e., the first direction. That is, the second portion 42 has a trapezoidal shape in its cross-section along the first direction. The first direction is as follows: Figure 2 The AA direction shown is a direction that is perpendicular to the upper surface of the secondary collector layer 2 and parallel to the arrangement direction of the collector contact metal 4 and the collector layer 3.

[0027] In one embodiment, the groove is trapezoidal in shape along the first direction section. At least one of the two sides forming the groove is not parallel to the first direction; that is, at least one of the two sides of the second part 42, or at least one of the two sides of at least one segment of the second part 42, is not parallel to the first direction, i.e., at a set angle. The groove can be configured as a trapezoidal structure with a wider top and narrower bottom, or vice versa.

[0028] In one embodiment, on a cross section along the first direction, the distance between the edge of the first portion 41 of the collector contact metal 4 and the base step is ≥0.1μm. Here, the edge of the first portion 41 refers to the edge near the collector layer 3, and the distance between it and the base step is the minimum distance between it and the edge of the collector layer 3.

[0029] In one embodiment, the first portion 41 and the second portion 42 of the current collector contact metal 4 are such that, in a cross section along the first direction, the distance between the edge of the second portion 42 on one side and the edge of the first portion 41 on the same side is ≥0.1μm. Here, the edge of the second portion 42 on one side is the edge that forms a second contact portion with the secondary current collector layer 2. One side refers to the side closer to the current collector layer 3 and / or the side farther away from the current collector layer 3.

[0030] In one embodiment, the depth of the groove into which the second portion 42 of the collector contact metal 4 is inserted is less than the thickness of the secondary collector layer 2, for example, the depth of the groove is 0.3 μm to 0.6 μm. Thus, a reasonable setting of the groove depth can avoid insufficient contact area between the collector contact metal 4 and the secondary collector layer 2 due to an excessively shallow groove, and can also avoid the possibility of the groove being too deep and penetrating the secondary collector layer 2.

[0031] Compared to the example Figure 2 Example Figure 3 By changing the shape of the collector metal 42 to a trapezoid, the contact area between the side of the second part 42 and the interface of the secondary collector layer 2 can be further increased, thereby further reducing the contact resistance.

[0032] In one embodiment, such as Figure 4 The cross-sectional view of the HBT device structure shown includes a substrate 1, a buffer layer 61, a secondary collector layer 2, an etch stop layer 62, a collector layer 3, a base layer 63, an emitter layer 64, an emitter cap layer 65, and an emitter ohmic contact layer 67. Emitter steps are formed by etching the emitter ohmic contact layer 67 and the emitter cap layer 65; base steps are formed by etching the emitter layer 64, the base layer 63, and the collector layer 3; and multiple secondary collector grooves are formed by etching the secondary collector 2. Emitter contact metal 68 is provided on the emitter ohmic contact layer 67; base contact metal 66 is provided on the base layer 63; and collector contact metal 4 (including at least a first portion 41 and a second portion 42) is provided on the secondary collector layer 2, forming a multi-segment collector contact metal structure. An isolation region 69 is formed in the secondary collector layer 2 away from the base step region through ion implantation.

[0033] The secondary collector layer 2 has multiple grooves, meaning the number of grooves is greater than 1. This can refer to the number of grooves corresponding to the second part 42 of the same collector contact metal 4 being greater than 1, meaning the second part 42 of the same collector contact metal 4 contains multiple segments. Alternatively, it can refer to the multiple collector contact metals 4 in the HBT device each corresponding to one or more grooves, meaning the second part 42 of each collector contact metal 4 contains one or more segments, etc.

[0034] In some embodiments, when the second portion 42 of a current collector contact metal 4 comprises multiple segments, the shapes and / or sizes of the different segments may be the same or different. For example, the number of grooves may be greater than one, and the different grooves may have the same shape and size, or the different grooves may have the same shape and different sizes, or the different grooves may have different shapes and the same size, or the different grooves may have different shapes and different sizes. For example, the different groove shapes may be at least one of rectangles, trapezoids, triangles, U-shapes, etc.

[0035] The second part 42 of the collector contact metal 4 includes multiple segments, which are not connected to each other and are respectively connected to the first part 41.

[0036] In one embodiment, the first portion 41 of the current collector contact metal has a distance ≥0.1 μm between its edge and the base step in a cross-section along the first direction. Here, the edge of the first portion 41 refers to the edge close to the current collector layer 3, and the distance between it and the base step is the minimum distance between the current collector layer 3 and the edge of the current collector layer 3.

[0037] In one embodiment, the first part 41 of the current collector contact metal and the second part 42 of the multi-segment structure, on the cross section along the first direction, the distance between the edge of the multi-segment structure on one side of the second part 42 and the edge of the first part 41 on the same side is ≥0.1μm. Here, the edge of the multi-segment structure on one side is the edge that forms the second contact portion with the secondary current collector layer 2. One side refers to the side closer to the current collector layer 3 and / or the side farther away from the current collector layer 3.

[0038] The depth of the groove inserted into the multi-segment structure in the second part 42 of the collector contact metal 4 is less than the thickness of the secondary collector layer 2. For example, the depth of the groove is 0.3μm to 0.6μm, and the depth is the depth along the first direction. In this way, the reasonable setting of the groove depth can avoid the groove being too shallow, resulting in insufficient contact area between the collector contact metal 4 and the secondary collector layer 2, and can also avoid the groove being too deep, which may penetrate the secondary collector layer 2.

[0039] Thus, the second part 42 of the multi-segment structure of the collector contact metal 4 is embedded in the secondary collector layer 2 through multiple grooves, thereby extending downward to form more contact surface with the secondary collector layer 2 without increasing the area occupied by the collector contact metal 4 on the upper surface of the secondary collector layer 2, thereby increasing the contact area and reducing the contact resistance.

[0040] In one embodiment, such as Figure 5 The cross-sectional view of the HBT device structure shown includes a substrate 1, a buffer layer 61, a secondary collector layer 2, an etch stop layer 62, a collector layer 3, a base layer 63, an emitter layer 64, an emitter cap layer 65, and an emitter ohmic contact layer 67. An emitter step is formed by etching the emitter ohmic contact layer 67 and the emitter cap layer 65; a base step is formed by etching the emitter layer 64, the base layer 63, and the collector layer 3; and a secondary collector step 23 is formed by etching the secondary collector 2. An emitter contact metal 68 is provided on the emitter ohmic contact layer 67; a base contact metal 66 is provided on the base layer 63; and a stepped collector contact metal 4 (including at least a third portion 43 and a fourth portion 44) is provided on the secondary collector layer 2. An isolation region 69 is formed in the secondary collector layer 2 away from the base step region by ion implantation.

[0041] The secondary collector layer 2 includes a first surface 21 and a second surface 22 with different heights. A stepped structure 23 is formed at the junction of the first surface 21 and the second surface 22. The collector contact metal 4 includes a third portion 43 covering the first surface 21 and a fourth portion 44 covering the second surface 22 and the stepped structure 23. The contact surface between the third portion 43 and the first surface 21 is the first contact portion, and the contact surface between the fourth portion 44 and the stepped structure 23 is the second contact portion.

[0042] For example, the upper surface of the secondary collector layer 2 includes protrusions, forming a first surface 21 and a second surface 22 with different heights, the height being the height along the first direction; the junction of the edge of the first surface 21 and the edge of the second surface 22 forms a stepped structure 23 based on the height difference; the third portion 43 covers the first surface 21, and the fourth portion 44 covers the second surface 22 and the stepped structure 23. The interface (i.e., contact surface) between the third portion 43 and the first surface 21 is the first contact portion, and the interface between the fourth portion 44 and the stepped structure 23 is the second contact portion. The fourth portion 44 also forms an interface with the second surface.

[0043] In some embodiments, the step structure 23 can be an acute angle, a right angle, or an obtuse angle structure. For example, when the step structure 23 is a right angle structure, the connection surface at the junction of the edge of the first surface 21 and the edge of the second surface 22 is perpendicular to the upper surface of the secondary collector layer 2; when the step structure 23 is an acute angle or an obtuse angle structure, the connection surface at the junction of the edge of the first surface 21 and the edge of the second surface 22 is not perpendicular to the upper surface of the secondary collector layer 2.

[0044] In one embodiment, the third portion 43 of the collector contact metal 4 has a distance ≥0.1 μm between its edge and the base step in a cross-section along the first direction. Here, the edge of the third portion 43 refers to the edge close to the collector layer 3, and the distance between it and the base step is the minimum distance between the edge of the collector layer 3 and the base step.

[0045] The third portion 43 covers the first surface 21. For example, the width of the third portion 43 on the aforementioned cross-section is 0.4 μm to 0.8 μm, thereby ensuring the support of the third portion 43 on the first surface 21 and improving the structural stability of the collector contact metal 4. Here, the width can refer to the width along the arrangement direction of the collector contact metal 4 and the collector layer 3.

[0046] In one embodiment, the height of the step structure 23 of the secondary collector layer 2 is less than the thickness of the secondary collector layer 2. For example, the height of the step structure 23 is 0.3 μm to 0.6 μm, where the height is along the first direction. This reasonable setting of the step height avoids insufficient contact area between the collector contact metal 4 and the secondary collector layer 2 due to an excessively low step height, and also avoids the possibility of the secondary collector layer 2 being etched through due to an excessively high step height.

[0047] Thus, by forming a step 23 through the height difference structure on the surface of the secondary collector layer 2, and placing the collector contact metal 4 on the step, a larger contact area can be formed based on the step structure 23, in addition to the contact surfaces of the collector contact metal 4 with the first surface 21 and the second surface 22, thereby reducing the contact resistance. That is, compared to simply covering the upper surface of the secondary collector layer with a single horizontal contact surface, the collector contact metal adds a contact portion with the secondary collector layer in a direction different from the horizontal, thus forming a structure that forms contact surfaces with the secondary collector layer in different directions. The second contact portion, based on the contact surface in a direction different from the horizontal, can form a larger contact area with the secondary collector layer without resulting in excessive coverage in the horizontal direction. This avoids excessive surface area occupation and, based on the negative correlation between contact resistance and contact area, generates more contact area, reducing the contact resistance between the collector contact metal and the secondary collector layer, thereby improving the performance of the HBT device.

[0048] In one embodiment, such as Figure 6 The cross-sectional view of the HBT device structure shown includes a substrate 1, a buffer layer 61, a secondary collector layer 2, an etch stop layer 62, a collector layer 3, a base layer 63, an emitter layer 64, an emitter cap layer 65, and an emitter ohmic contact layer 67. An emitter step is formed by etching the emitter ohmic contact layer 67 and the emitter cap layer 65. A base step is formed by etching the emitter layer 64, the base layer 63, and the collector layer 3. A secondary collector step 23 is formed by etching the secondary collector 2, and a groove is further formed by etching the secondary collector 2. An emitter contact metal 68 is provided on the emitter ohmic contact layer 67; a base contact metal 66 is provided on the base layer 63; and a collector contact metal 4 (including at least a third portion 43, a fourth portion 44, and a fifth portion 45) is provided on the secondary collector layer 2. An isolation region 69 is formed in the region of the secondary collector layer 2 away from the base step by ion implantation.

[0049] The current collector contact metal 4 further includes a fifth portion 45 that is connected to the third portion 43, and the secondary current collector layer 2 has at least one first groove, with the fifth portion 45 filling the first groove; And / or, the fifth portion 45 of the collector contact metal is connected to the fourth portion 44, and the secondary collector layer has at least one second groove, the fifth portion 45 being filled in the second groove.

[0050] In some embodiments, the shape of the fifth portion 45 in the current collector contact metal 4 may refer to the aforementioned... Figure 2 and Figure 3 The structure and implementation of the second part 42 in the embodiment, for example, the shape of 45 can be at least one of rectangle, trapezoid, triangle, U-shape, etc.

[0051] In some embodiments, the fifth portion 45 of the collector contact metal 4 may comprise one or more segments. For example, in this embodiment, the fifth portion 45 may refer to the aforementioned... Figure 4 The second part 42 in the embodiment has a multi-segment structure and its implementation method.

[0052] In some embodiments, the fifth part 45 may include one or more segments that are all connected to the third part 43, or all connected to the fourth part 44, or at least one segment may be connected to the third part 43 and the remaining segments may be connected to the fourth part 44.

[0053] The third portion 43 of the current collector contact metal 4 has a distance ≥0.1 μm between its edge and the base step in a cross-section along the first direction. Here, the edge of the third portion 43 refers to the edge close to the current collector layer 3, and the distance between it and the base step is the minimum distance between the edge of the current collector layer 3 and the edge of the current collector layer 3.

[0054] The third portion 43 covers the first surface 21. For example, the width of the third portion 43 is 0.4μm to 0.8μm, thereby ensuring the support of the third portion 43 on the first surface 21 and improving the structural stability of the collector contact metal 4. Here, the width can refer to the width along the arrangement direction of the collector contact metal 4 and the collector layer 3.

[0055] In one embodiment, the total height of the stepped structure 23 and the fifth portion 45 of the secondary collector layer 2 is less than the thickness of the secondary collector layer 2.

[0056] Thus, by combining the two methods of setting steps on the secondary collector layer 2 and inserting the secondary collector layer 2 through grooves, the contact area between the collector contact metal 4 and the secondary collector layer 2 can be further increased, thereby reducing the contact resistance.

[0057] In some embodiments, such as Figures 7-10The cross-sectional view of the HBT device structure shown includes a substrate 1, a buffer layer 61, a secondary collector layer 2, a low bandgap semiconductor material layer 5, an etch stop layer 62, a collector layer 3, a base layer 63, an emitter layer 64, an emitter cap layer 65, and an emitter ohmic contact layer 67. Emitter steps are formed by etching the emitter ohmic contact layer 67 and the emitter cap layer 65. Base steps are formed by etching the emitter layer 64, the base layer 63, and the collector layer 3. Secondary collector steps 23 and / or grooves are formed by etching the secondary collector 2. An emitter contact metal 68 is provided on the emitter ohmic contact layer 67; a base contact metal 66 is provided on the base layer 63; and a collector contact metal 4 is provided on the secondary collector layer 2. An isolation region 69 is formed in the secondary collector layer 2 away from the base steps by ion implantation.

[0058] The secondary collector layer 2 may further include: at least one low bandgap semiconductor material layer 5; the material of the low bandgap semiconductor material layer 5 is InGaAs and / or GaAsSb, etc.; the bandgap of the semiconductor material layer 5 is lower than the bandgap of the secondary collector layer 2; the collector contact metal 4 is in contact with at least one low bandgap semiconductor material layer 5.

[0059] In one embodiment, such as Figure 7 As shown, the low bandgap semiconductor material layer 5 can be located in the secondary collector layer 2 and is in contact with the side of the second portion 42 (i.e. the second contact portion). Here, the side of the second portion 42 corresponds to the side edge on the cross section along the first direction, i.e. the side edge that forms the second contact portion with the secondary collector layer 2.

[0060] In one embodiment, such as Figure 8 As shown, the low bandgap semiconductor material layer 5 can be located in the secondary collector layer 2 and is in contact with the side surface (i.e. the second contact portion) and bottom surface of the second portion 42. Here, the bottom surface of the second portion 42 corresponds to the bottom edge on the cross section along the first direction, and the bottom surface in contact with the second portion 42 is the bottom surface away from or away from the first portion 41.

[0061] In some embodiments, when the upper surface of the secondary collector layer 2 includes a first surface 21 and a second surface 22 with different heights, the low bandgap semiconductor material layer 5 is located between the first surface 21 and the second surface 22, and / or below the second surface 22.

[0062] In one embodiment, the low bandgap semiconductor material layer 5 may be at least in contact with the fourth portion 44, for example, at least with the side and / or bottom surface of the fourth portion 44. Here, the side in contact may refer to the side covering the stepped structure 23, and the bottom surface may refer to the bottom surface near the second surface 22.

[0063] In one embodiment, such as Figure 9As shown, the low bandgap semiconductor material layer 5 is located between the first surface 21 and the second surface 22, and is in contact with the fourth portion 44, for example, in contact with the side of the fourth portion 44.

[0064] In one embodiment, such as Figure 10 As shown, the low bandgap semiconductor material layer 5 is located below the second surface 22 and is in contact with the side of the fifth portion 45.

[0065] It should be noted that the low bandgap semiconductor material layer 5 can contact the collector metal 4 at any location, for example, it can contact at any location at at least one of the first portion 41 to the fifth portion 45. Figures 2-6 In all the structures shown, the arrangement strategy of having the low bandgap semiconductor material layer 5 in contact with the collector metal 4 at any position can be adopted.

[0066] Thus, by setting a low bandgap semiconductor material layer 5 to form an ohmic contact with the collector contact metal 4, the collector contact resistance can be further reduced based on the low bandgap of the material.

[0067] In this embodiment, the fabrication process of the HBT device may include: providing a substrate; sequentially epitaxially forming an epitaxial layer on the substrate, the epitaxial layer comprising a buffer layer, a secondary collector layer, a low bandgap semiconductor material layer, an etch stop layer, a collector layer, a base layer, an emitter layer, an emitter cap layer, and an emitter ohmic contact layer; etching the epitaxial layer to form emitter steps and base steps, and etching the secondary collector layer to form collector steps or grooves; depositing emitter contact metal and base contact metal on the emitter steps and base steps; depositing the collector contact metal on the secondary collector layer; wherein the contact surface between the collector contact metal and the secondary collector layer includes at least a first contact portion and a second contact portion; the first contact portion is parallel to the upper surface of the secondary collector layer on the side away from the substrate, and the second contact portion is at a set angle relative to the first contact portion. An isolation region is formed in the region of the secondary collector layer away from the base steps by ion implantation.

[0068] In some embodiments, etching the secondary collector layer includes: A groove is formed by etching the upper surface of the secondary collector layer; And / or, a protrusion is formed by etching on the upper surface of the secondary collector layer, the protrusion comprising a first surface and a second surface of different heights, wherein a stepped structure is formed at the junction of the first surface and the second surface.

[0069] In one embodiment, etching the secondary collector layer 2 may refer to etching the upper surface of the secondary collector layer 2. For example, it may include etching to form a groove on the upper surface of the secondary collector layer 2, and / or etching to form a protrusion on the upper surface of the secondary collector layer 2, the protrusion comprising a first surface 21 and a second surface 22 of different heights.

[0070] In one embodiment, the current collector contact metal 4 is formed by vapor deposition on the upper surface of the secondary current collector layer 2, which may include: vapor deposition of the current collector contact metal 4 on the upper surface of the secondary current collector layer 2 based on a groove, and / or vapor deposition of the current collector contact metal 4 based on the first surface 21 and the second surface 22.

[0071] In one embodiment, each of the current collector contact metals 4 includes: a first portion 41 and a second portion 42 in contact; wherein the first portion 41 covers the upper surface of the secondary current collector layer 2, and the projected area of ​​the contact surface between the second portion 42 and the secondary current collector layer 2 in a first direction is greater than 0. The second portion 42 may be filled in a groove.

[0072] In one embodiment, the third portion 43 covers the first surface 21, and the fourth portion 44 covers the second surface 22 and also covers the stepped structure 23.

[0073] In one embodiment, preparing the base contact metal 66 on the emitter layer 64 may include: depositing the base contact metal 66 on the emitter layer 64 by vapor deposition, and then using a tempering process to allow the base contact metal 66 to penetrate down into the base layer 63 to form an ohmic contact.

[0074] In one embodiment, fabricating the collector contact metal 4 on the secondary collector layer 2 may include: depositing the collector contact metal 4 on the secondary collector layer 2 by vapor deposition, and then using a tempering process to react the collector contact metal 4 with the secondary collector layer 2 or the low bandgap semiconductor layer 5 in the secondary collector layer to form a metal ohmic contact.

[0075] In one embodiment, etching can refer to either wet etching or dry etching.

[0076] In some embodiments, the formation of the isolation region by ion implantation includes: Based on the first photomask, an isolation region 69 is formed at the edge of the secondary collector layer 2 through photoresist coating, photolithography, development, and ion implantation. Then, based on the first photomask, the upper surface of the secondary collector layer 2 is divided into a first surface 21 and a second surface 22 with different heights by etching. That is, the etched step structure 23 of the secondary collector layer 2 can share the same photomask for the ion implantation isolation process. Figure 11As shown, the isolation region 69 overlaps with the collector contact metal 4 in the first direction; Alternatively, based on the first photomask, an isolation region 69 is formed at the edge of the secondary collector layer 2 through photoresist coating, photolithography, development, and ion implantation. Then, based on the second photomask, the upper surface of the secondary collector layer 2 is divided into a first surface 21 and a second surface 22 with different heights through photoresist coating, photolithography, development, and etching. That is, the etching of the stepped structure 23 of the secondary collector layer 2 and the ion implantation isolation are performed separately using a single photomask. Figure 2-10 As shown in either of the above, the isolation region 69 and the collector contact metal 4 do not overlap in the first direction.

[0077] Here, the overlap between the isolation region 69 and the collector contact metal 4 can be interpreted as an overlap in their vertical projection areas on the substrate 1. Similarly, the absence of overlap means that their vertical projection areas on the substrate 1 do not overlap. Thus, different relative positions of the isolation region 69 and the collector contact metal 4 can be achieved using different process methods, allowing for flexible adaptation to various device process requirements and satisfying different structural positional relationships under diverse needs.

[0078] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0079] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An HBT device, characterized in that, include: Collector structure; the collector structure includes a secondary collector layer, a collector layer disposed above the secondary collector layer, and a collector contact metal; The current collector contact metal is in contact with the secondary current collector layer, and the contact surface between the current collector contact metal and the secondary current collector layer includes at least a first contact portion and a second contact portion that are interconnected. The first contact portion is parallel to the upper surface of the collector layer in the secondary collector layer, and the second contact portion is at a predetermined angle relative to the first contact portion.

2. The HBT device according to claim 1, characterized in that, The secondary collector layer has at least one groove, and the collector contact metal includes a first portion protruding outside the groove and a second portion filling the groove; The contact surface between the first portion and the upper surface of the secondary collector layer is the first contact portion, and the contact surface between the side of the second portion and the secondary collector layer is the second contact portion.

3. The HBT device according to claim 2, characterized in that, The number of grooves is greater than 1; wherein, different grooves have the same shape and the same size, or different grooves have the same shape and different sizes, or different grooves have different shapes and the same size, or different grooves have different shapes and different sizes.

4. The HBT device according to claim 2, characterized in that, The vertical projection area of ​​the second part on the substrate is located within the vertical projection area of ​​the first part on the substrate.

5. The HBT device according to claim 2, characterized in that, The depth of the groove is less than the thickness of the secondary collector layer.

6. The HBT device according to claim 2, characterized in that, The groove has a cross-sectional shape of at least one of rectangle, trapezoid, triangle and U-shape along the direction perpendicular to the upper surface of the secondary collector layer.

7. The HBT device according to claim 1, characterized in that, The secondary collector layer includes a first surface and a second surface with different heights, and a stepped structure is formed at the junction of the first surface and the second surface; The current collector contact metal includes a third portion covering the first surface and a fourth portion covering the second surface and covering the stepped structure; The contact surface between the third part and the first surface is the first contact portion, and the contact surface between the fourth part and the stepped structure is the second contact portion.

8. The HBT device according to claim 7, characterized in that, The current collector contact metal also includes a fifth part; The fifth part is connected to the third part, and the second collector layer has a first groove, the fifth part being filled in the first groove; And / or, the fifth portion is connected to the fourth portion, and the second collector layer has a second groove, the fifth portion being filled in the second groove.

9. The HBT device according to claim 7, characterized in that, The height difference between the first surface and the second surface is less than the thickness of the secondary collector layer.

10. The HBT device according to claim 1, characterized in that, The minimum distance between the current collector contact metal and the edge of the current collector layer is greater than 0.1 μm.

11. The HBT device according to claim 1, characterized in that, The HBT device further includes a base structure located on the collector layer and an emitter structure disposed on the base structure: The base structure includes a base layer located on the current collector layer and a base contact metal in contact with the base layer; The emitter structure includes an emitter layer on the base layer, an emitter cap layer on the emitter layer, an emitter ohmic contact layer on the emitter cap layer, and an emitter contact metal on the emitter ohmic contact layer.

12. The HBT device according to any one of claims 1 to 11, characterized in that, The secondary collector layer further includes: at least one low bandgap semiconductor material layer; the bandgap of the low bandgap semiconductor material layer is lower than the bandgap of the secondary collector layer. The collector contact metal is in contact with at least one layer of the low bandgap semiconductor material.

13. The HBT device according to claim 12, characterized in that, The secondary collector layer includes a first surface and a second surface with different heights; The low bandgap semiconductor material layer is located between the first surface and the second surface, and / or below the second surface.

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