A packaging structure for improving high-power working characteristics of detectors

Abstract

The present invention provides a packaging structure for improving the high-power working characteristics of a detector, comprising: a base, a detector chip, a tube cap, and a lens assembly. The present invention adopts a lens assembly with a uniform light effect to change the energy distribution of the light spot irradiated on the detector chip from a Gaussian distribution to a uniform distribution, thereby suppressing the state of excessively high local carrier density, and further improving the performance of the detector at high power.

Description

Technical Field

[0001] The present invention belongs to the field of optical communication technology, and in particular relates to a packaging structure for improving the high-power working characteristics of a detector. Background Art

[0002] Photodetectors can convert optical signals into electrical signals and have been widely used in optical communications, laser radar, imaging and other fields. As the core component of optical communication technology, photodetectors have high requirements for bandwidth. However, when the incident light power is large, a carrier shielding effect will occur, that is, a large number of photogenerated electron holes generated in the absorption area of ​​the photodetector will generate a built-in electric field in the opposite direction of the external electric field, thereby slowing down the drift speed of carriers, which in turn leads to a significant decrease in the bandwidth of the photodetector.

[0003] In order to reduce or eliminate the carrier shielding effect, technicians in this field have proposed a photoelectric detection component that can improve the saturated optical power bandwidth. The specific implementation method is that when the optical signal is received by the input end, it is distributed to n photodetector chips and outputs n photocurrents. The signal synthesis matching unit then superimposes the n photocurrents. In addition, technicians in this field have also proposed a waveguide photodetector that divides the incident light into four paths through a beam splitter to avoid excessive concentration of the incident light power in the absorption layer, thereby generating a carrier shielding effect. The above methods all require special design of the structure of the photodetector or splitting the incident light, which will not only increase the difficulty of the process and the manufacturing cost, but also greatly increase the size of the device, resulting in greater limitations in practical applications. Summary of the invention

[0004] To solve the above technical problems, the present invention provides a packaging structure that improves the high-power working characteristics of the detector. In order to have a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important components or describe the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0005] The present invention adopts the following technical solution:

[0006] In some optional embodiments, a packaging structure is provided for improving the high-power operating characteristics of the detector, including: a detector chip and a lens assembly encapsulated on the light receiving side of the detector chip, wherein the external light beam is shaped into a flat-top beam by the lens assembly and then irradiated onto the photosensitive surface of the detector chip.

[0007] Furthermore, the packaging structure for improving the high-power working characteristics of the detector also includes: a base and a tube cap arranged on the base and encapsulating the detector chip inside itself, and the detector chip is mounted on the base.

[0008] Furthermore, the lens assembly is composed of a first lens and / or a second lens; the first lens is arranged on the tube cap; the second lens is adhered to the photosensitive surface of the detector chip, or adhered to the base through a bracket or tube legs.

[0009] Furthermore, the packaging structure for improving the high-power working characteristics of the detector also includes: an electric chip, which is arranged on the base; the detector chip is arranged on the electric chip, or is arranged on the base in parallel with the electric chip.

[0010] Furthermore, the packaging structure for improving the high-power working characteristics of the detector also includes: a pad block, which is arranged on the base; the detector chip and the electric chip are arranged on the base through the pad block.

[0011] Furthermore, the pads of the detector chip and the electrical chip are connected to the pins of the base through wire bonding.

[0012] Furthermore, the pads of the detector chip are connected to the electric chip by wire bonding, or connected to the electric chip by flip chip.

[0013] Furthermore, the bonding wire is one or more of Au wire, Pt wire or Cu wire.

[0014] Furthermore, the first lens includes but is not limited to a Fresnel lens, a grating lens, and a lens group black box; when the second lens alone realizes the uniform light effect, the first lens is a convex lens, a concave lens, or a plane lens.

[0015] Furthermore, the detector chip is a photodiode chip or an avalanche photodiode tube chip, and the detector chip is made of Group IV material or Group IIIV material.

[0016] The beneficial effects brought by the present invention are as follows: the present invention adopts a lens assembly with a uniform light effect to change the energy distribution of the light spot irradiated on the detector chip from a Gaussian distribution to a uniform distribution, thereby suppressing the state of excessive local carrier density and further improving the performance of the detector under high power; the present invention has a simple structure, which is not only conducive to efficient packaging and reduces manufacturing difficulty, but also has greater versatility; it has the advantage of low cost while also ensuring the bandwidth and performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of one embodiment of the packaging structure of the present invention;

[0018] Figure 2 is a schematic diagram of another embodiment of the packaging structure of the present invention;

[0019] Figure 3 is a schematic diagram of yet another embodiment of the packaging structure of the present invention;

[0020] Figure 4 is a schematic diagram of one embodiment of the lens assembly of the present invention;

[0021] Figure 5 is a schematic diagram of another embodiment of the lens assembly of the present invention;

[0022] Figure 6 is a schematic diagram of yet another embodiment of the lens assembly of the present invention;

[0023] Figure 7 It is a curve diagram showing the power density changing with the radial position of the light spot when the light spot energy is Gaussian distribution;

[0024] Figure 8 It is one of the power density distribution diagrams of the external light beam after being homogenized by the lens assembly of the present invention;

[0025] Fig. 9 It is another power density distribution diagram of the external light beam after being homogenized by the lens assembly of the present invention;

[0026] Fig.10 It is another power density distribution diagram of the external light beam after being homogenized by the lens assembly of the present invention;

[0027] Fig.11 It is another power density distribution diagram of the external light beam after being homogenized by the lens assembly of the present invention;

[0028] Fig.12 is a schematic diagram of a Fresnel lens;

[0029] Fig.13 is a schematic diagram of one type of grating lens;

[0030] Fig.14 is a schematic diagram of another type of grating lens;

[0031] Fig.15 It is a schematic diagram of a specific usage scenario of the present invention. DETAILED DESCRIPTION

[0032] The following description and accompanying drawings fully demonstrate specific embodiments of the present invention so that those skilled in the art can practice them. Other embodiments may include structural, logical, electrical, process and other changes. The embodiments represent possible variations only. Unless clearly required, separate components and functions are optional, and the order of operation may vary. The parts and features of some embodiments may be included in or replace the parts and features of other embodiments.

[0033] In some illustrative embodiments, Figure 1-6 As shown, the present invention provides a packaging structure for improving the high-power working characteristics of a detector, including: a base 101, a detector chip 102, a tube cap 103 and a lens assembly.

[0034] The tube cap 103 is arranged on the base 101 and is surrounded by the base 101 to form a packaging cavity. The detector chip 102 is located in the packaging cavity, that is, the tube cap 103 packages the detector chip 102 inside itself. Specifically, the detector chip 102 is mounted on the base 101. The lens assembly is packaged on the light receiving side of the detector chip 102. The light receiving side mentioned in this article refers to the side where the photosensitive surface of the detector chip 102 faces the incident light beam. The structural design of the present invention enables the external light beam to be shaped into a flat-top beam by the lens assembly and then irradiated onto the photosensitive surface of the detector chip 102.

[0035] like Figure 7 As shown, the spot energy distribution of the external light beam is Gaussian distribution. When high-power signal light irradiates the photosensitive surface, due to the carrier shielding effect, the photogenerated carriers cannot reach the saturation drift velocity, and the bandwidth and performance of the photodetector will be significantly reduced. The lens component of the packaging structure of the present invention has a uniform light effect, which plays a role in shaping the external light beam, that is, shaping the external light beam into a flat-top beam. The present invention introduces a lens component with a uniform light effect into the packaging structure to change the spot energy from Gaussian distribution to non-Gaussian distribution, such as Figure 8-11 As shown, the power density is more evenly distributed along the radial direction, and the power density at the center of the spot is significantly reduced, thereby improving the working performance of the detector at high power.

[0036] The present invention further includes: an electric chip 201 and a spacer block 202 .

[0037] The electrical chip 201 refers to all chips that can transmit and process electrical signals, and may be a transimpedance amplifier, or other types of electrical chips and corresponding PCB boards, etc. The electrical chip 201 is disposed on the base 101. The detector chip 102 is disposed on the electrical chip 201, or is disposed on the base 101 in parallel with the electrical chip 201.

[0038] The pad 202 is arranged on the base 101, and the detector chip 102 and the electric chip 201 are arranged on the base 101 through the pad 202, wherein the pad 202 is used to adjust the height of the detector chip 102 and the electric chip 201. Since the thickness of the detector chip 102 and the thickness of the electric chip 201 are likely to be different, the height difference caused by the different thicknesses will increase the length of the wire bonding, thereby affecting the RF performance of the component. Therefore, the present invention adds the pad 202 during packaging, and can adjust the detector chip 102 and the electric chip 201 to the same height, reduce the wire bonding length, and ensure the performance of the component.

[0039] The pads of the detector chip 102 and the electrical chip 201 are connected to the pins of the base 101 through wire bonding 203. Wire bonding refers to the use of metal wires, heat pressure or ultrasonic energy to complete the connection of the internal interconnection wiring of the solid-state circuit in the microelectronic device, that is, the connection between the chip and the circuit or lead frame is simple.

[0040] The pads of the detector chip 102 are connected to the electrical chip 201 through bonding wires 203, or connected to the electrical chip 201 through a flip chip method. Flip chip is a packaging technology that adds bumps to the chip connection points and then flips the chip over to connect the bumps directly to the substrate.

[0041] The present invention adopts a wire bonding or flip chip packaging method, which has the advantage of a simple packaging method.

[0042] The bonding wire 203 is one or more of Au wire, Pt wire or Cu wire, and has good conductive properties.

[0043] The lens assembly is composed of the first lens 104 and / or the second lens 401, that is, the light homogenization effect is achieved directly by the first lens 104, or by the second lens 401 alone, or by both the first lens 104 and the second lens 401.

[0044] The first lens 104 is disposed on the tube cap 103. The second lens 401 is attached to the photosensitive surface of the detector chip 102, or attached to the base 101 through the bracket 105 or the tube leg, or attached to the pad 202 through the bracket 105 or the tube leg. When the first lens 104 and the second lens 401 jointly achieve the uniform light effect, the second lens 401 is located between the first lens 104 and the detector chip 102. The various lens combination methods enable the packaging structure of the present invention to be packaged and adjusted according to application requirements and actual conditions, thereby having high versatility, and the various combination methods can ensure a good uniform light effect, avoiding or greatly reducing the carrier shielding effect.

[0045] The first lens 104 includes but is not limited to a Fresnel lens, a grating lens, and a lens group black box. Fig.12 As shown in the figure, Fresnel lens, also known as spiral lens, is mostly made of thin sheets of polyolefin material injection molding, and some are made of glass. One side of the lens surface is smooth, and the other side is engraved with concentric circles from small to large. Its texture is designed according to the interference and disturbance of light, as well as the relative sensitivity and receiving angle requirements. Figure 13-14 As shown, the grating lens is made of two or more materials with different refractive indices alternately, or the same material with different thicknesses alternately. The effect is that when light passes through the lens, the optical path in different areas is different, resulting in diffraction. The lens group black box refers to an optical component composed of multiple lenses, which form images in sequence and ultimately achieve a uniform light effect.

[0046] When the light uniformity effect is achieved by the second lens 401 alone, the first lens 104 can be any optical lens that does not change the energy distribution of the light spot, such as a convex lens, a concave lens, a plane lens, etc.

[0047] The detector chip 102 is a photodiode chip or an avalanche photodiode chip, and is made of Group IV materials, such as Ge, Si, Ge x Si 1-x, etc., or Group III V materials, such as GaAs, InGaAs, etc.

[0048] like Fig.15 As shown, in specific applications, the base 101 is affixed with an electric chip 201, a detector chip 102 and a pad 202, and connected by bonding wires 203. The first lens 104 on the cap 103 is a diffraction lens that can achieve the effect of flat-top beam conversion. When in use, the optical fiber adapter 601 is welded outside the structure. The light to be received is Gaussian when it is emitted from the optical fiber 602 in the adapter, and is shaped by the first lens 104 into a flat-top beam with uniform radial distribution of power density. The power density at the center of the spot is significantly reduced, and the performance of the component at high power is improved.

[0049] Those skilled in the art will also appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the embodiments herein can all be implemented as electronic hardware, computer software, or a combination thereof. In order to clearly illustrate the interchangeability between hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above around their functions. Whether such functions are implemented as hardware or software depends on specific applications and the design constraints imposed on the entire system. A skilled person can implement the described functions in an alternative manner for each specific application, but such implementation decisions should not be interpreted as departing from the scope of protection of the present disclosure.

Claims

1. A packaging structure for improving the high-power working characteristics of a detector, characterized in that: include: A detector chip and a lens assembly packaged on the light receiving side of the detector chip, wherein the external light beam is shaped into a flat-top beam by the lens assembly and then irradiated onto the photosensitive surface of the detector chip; a lens assembly with a uniform light effect is used to change the energy distribution of the light spot irradiated onto the detector chip from a Gaussian distribution to a uniform distribution, thereby suppressing the state of excessively high local carrier density, and thereby improving the performance of the detector at high power; The pad is arranged on the base, and the detector chip and the electric chip are arranged on the base through the pad, wherein the pad is used to adjust the height of the detector chip and the electric chip; since the thickness of the detector chip is different from that of the electric chip, the height difference caused by the different thicknesses will lengthen the length of the wire bonding, thereby affecting the RF performance of the component. The pad is added during packaging to adjust the detector chip and the electric chip to the same height, thereby reducing the wire bonding length.

2. The packaging structure for improving the high-power working characteristics of the detector according to claim 1, characterized in that: Also includes: A base and a tube cap which is arranged on the base and encapsulates the detector chip inside the base, and the detector chip is mounted on the base.

3. The packaging structure for improving the high-power working characteristics of the detector according to claim 2, characterized in that: The lens assembly consists of a first lens and / or a second lens; The first lens is disposed on the tube cap; The second lens is adhered to the photosensitive surface of the detector chip, or is adhered to the base through a bracket or a tube leg.

4. The packaging structure for improving the high-power working characteristics of the detector according to claim 3, characterized in that: Also includes: An electric chip, wherein the electric chip is disposed on the base; The detector chip is arranged on the electric chip, or is arranged on the base in parallel with the electric chip.

5. The packaging structure for improving the high-power working characteristics of the detector according to claim 4, characterized in that: The pads of the detector chip and the electrical chip are connected to the pins of the base through wire bonding.

6. The packaging structure for improving the high-power working characteristics of the detector according to claim 5, characterized in that: The pads of the detector chip are connected to the electric chip by wire bonding, or by flip chip.

7. The packaging structure for improving the high-power working characteristics of the detector according to claim 6, characterized in that: The bonding wire is one or more of Au wire, Pt wire or Cu wire.

8. The packaging structure for improving the high-power working characteristics of the detector according to claim 7, characterized in that: The first lens includes but is not limited to a Fresnel lens, a grating lens, and a lens group black box; when the second lens alone realizes the uniform light effect, the first lens is a convex lens, a concave lens, or a plane lens.

9. The packaging structure for improving the high-power working characteristics of the detector according to claim 8, characterized in that: The detector chip is a photodiode chip or an avalanche photodiode tube chip, and the detector chip is made of Group IV material or Group IIIV material.

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