A terahertz chip packaging structure based on suspended microstrip flip

Abstract

The present invention discloses a terahertz chip packaging structure based on suspended microstrip inverted buckle, comprising an upper cavity, a lower cavity, an input probe transition structure, a chip and an output probe transition structure, wherein the upper cavity cover forms an input waveguide and an output waveguide on the lower cavity, the input probe transition structure comprises an input probe, an input suspended microstrip matching circuit and an input probe transition structure quartz substrate, the input probe is connected to the input suspended microstrip matching circuit and is located on the input probe transition structure quartz substrate, the output probe transition structure comprises an output probe, an output suspended microstrip matching circuit and an output probe transition structure quartz substrate, the output probe is connected to the output suspended microstrip matching circuit and is located on the output probe transition structure quartz substrate, and the chip is connected to the input suspended microstrip matching circuit and the output suspended microstrip matching circuit. The present invention has simple structure, is easy to process, has wide bandwidth and low loss.

Description

Technical Field

[0001] The present invention relates to the technical field of millimeter wave communication, and in particular to a terahertz chip packaging structure based on suspended microstrip flip-up. Background Art

[0002] 5G communication has been gradually applied to commercialization, and the research on terahertz communication is also in full swing. Each communication module in terahertz communication works above 100GHz, and the terahertz frequency band modulator chip, low noise amplifier chip, mixer chip, frequency multiplier chip and power amplifier chip are used. In the terahertz frequency band, the connection of these modules is no longer directly connected using PCB boards and wires like low-frequency communication links, because the skin effect of the wire and the radiation of the antenna effect must be considered, and the signal loss will become very large, which greatly reduces the efficiency of communication or even makes it impossible to communicate effectively. Therefore, in the high-frequency communication link, it is necessary to encapsulate a single module into a cavity, and use the waveguide formed by the cavity to transmit the input and output signals of a single module to achieve the connection of each communication module.

[0003] The traditional technology for encapsulating the terahertz chips of each communication in the cavity is to use gold wire to connect the chip with the transition structure, so as to form a signal transmission path of probe waveguide-transition structure-chip-probe transition structure-waveguide. However, the use of gold wire for connection will introduce a large discontinuity, the parasitic inductance is too large, resulting in difficulty in matching and greatly reduced bandwidth. Moreover, when processing the gold wire connection, due to the large processing deviation, it cannot be guaranteed that the gold wire is bonded to the designed transition structure position, and the test results of the final processed packaging module will deviate greatly from the expected results of the design, either the center frequency offset bandwidth will be narrowed, or the insertion loss will be too high, or both. Moreover, even if the position accuracy of the processing meets the requirements, the height of the gold wire may be different in the next processing, which will make the test results of the products processed twice very different, resulting in a very low product yield. When using gold wire to connect the transition structure and the chip, improving the processing accuracy of the gold wire will greatly increase the packaging cost of the terahertz chip, which is not conducive to low-cost design projects. Summary of the invention

[0004] The object of the present invention is to provide a terahertz chip packaging structure based on suspended microstrip flip-up which has simple structure, is easy to process, has wide bandwidth and low loss in view of the deficiencies in the prior art.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A terahertz chip packaging structure based on suspended microstrip inverted buckle, characterized in that it includes an upper cavity, a lower cavity, an input probe transition structure, a chip and an output probe transition structure, the upper cavity covers the lower cavity to form an input waveguide, an output waveguide and a cavity for placing the input probe transition structure, the chip and the output probe transition structure, the input probe transition structure includes an input probe, an input suspended microstrip matching circuit and an input probe transition structure quartz substrate, the input probe is connected to the input suspended microstrip matching circuit and is located on the input probe transition structure quartz substrate, the output probe transition structure includes an output probe, an output suspended microstrip matching circuit and an output probe transition structure quartz substrate, the output probe is connected to the output suspended microstrip matching circuit and is located on the output probe transition structure quartz substrate, the chip is connected to the input suspended microstrip matching circuit and the output suspended microstrip matching circuit, the electromagnetic wave is input through the input waveguide, and is output from the output waveguide after passing through the input probe transition structure, the chip and the output probe transition structure.

[0007] Furthermore, the input probe transition structure and the output probe transition structure are inverted on the chip and are connected to the chip via conductive adhesive respectively.

[0008] Furthermore, the input suspended microstrip matching circuit and the output suspended microstrip matching circuit adopt a high-low impedance transmission line structure.

[0009] Furthermore, the input waveguide and the output waveguide are provided with a reduced height portion near the probe end.

[0010] The present invention has the following effects:

[0011] (1) Compared with the packaging structure of gold wire jumping, the present invention has simple process, low cost, easy processing and high precision;

[0012] (2) The present invention reduces transmission loss and expands bandwidth by using a suspended microstrip matching circuit;

[0013] (3) The present invention has a high tolerance for processing errors. The tolerance for the length and width of the microstrip line can reach 10um, and the tolerance for the processing error of the cavity can reach 25um.

[0014] (4) The present invention has a simple structure and is suitable for packaging of most terahertz chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the appearance structure of the present invention;

[0016] Figure 2 It is a schematic diagram of the internal structure of the present invention;

[0017] Figure 3A schematic diagram of the input probe transition structure and the chip flip connection of the present invention;

[0018] Figure 4 This is the electromagnetic simulation result diagram of the present invention.

[0019] Markings in the figure: 1. Input waveguide; 2. Waveguide input end corner; 3. Input height reduction chamfer; 4. Input probe transition structure quartz substrate; 5. Input probe; 6. Input suspended microstrip matching circuit; 7. Chip SiC substrate; 8. Engraved metal block; 9. 50 ohm transmission line; 10. Output suspended microstrip matching circuit; 11. Output probe transition structure quartz substrate; 12. Output probe; 13. Output height reduction chamfer; 14. Waveguide output end corner; 15. Output waveguide; 16. Conductive glue. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] like Figure 1 , Figure 2 As shown, the terahertz chip packaging structure based on suspended microstrip inversion provided in this embodiment includes an upper cavity, a lower cavity, an input probe transition structure, a chip and an output probe transition structure. The upper cavity covers the lower cavity to form an input waveguide 1, an output waveguide 15 and a cavity for placing the input probe transition structure, the chip and the output probe transition structure. The input probe transition structure includes an input probe 5, an input suspended microstrip matching circuit 6 and an input probe transition structure quartz substrate 4. The input probe 5 is connected to the input suspended microstrip matching circuit 6 and is located on the input probe transition structure quartz substrate 4. The output probe transition structure includes an output probe 12, an output suspended microstrip matching circuit 10 and an output probe transition structure quartz substrate 11. The output probe 12 is connected to the output suspended microstrip matching circuit 10 and is located on the output probe transition structure quartz substrate 11. The chip includes a chip SiC substrate 7, an engraved metal block 8 and a 50 ohm transmission line 9. The chip is connected to the input suspended microstrip matching circuit 6 and the output suspended microstrip matching circuit 10. The specific connection is as follows Figure 2 As shown, the input probe transition structure quartz substrate 4 is placed upside down on the chip SiC substrate 7, and the input suspension microstrip matching circuit 6 is connected to the 50-ohm transmission line 9 through the conductive glue 16. Since the input probe transition structure quartz substrate 4 is transparent, it is convenient to align the position. Similarly, the output probe transition structure quartz substrate 11 is also placed upside down on the chip SiC substrate 7, and the output suspension microstrip matching circuit 10 is connected to the 50-ohm transmission line 9 through the conductive glue 16. When in use, the electromagnetic wave is input through the input waveguide 1, and after passing through the input probe transition structure, the chip and the output probe transition structure, it is output from the output waveguide 15.

[0022] In this embodiment, the input suspended microstrip matching circuit 6 and the output suspended microstrip matching circuit 10 adopt a high-low impedance transmission line structure.

[0023] In this embodiment, the ports of the input waveguide and the output waveguide are located on the same horizontal line, and the placement position of the chip and probe transition structure is perpendicular to the horizontal line. In this way, when the chip and probe transition structure are too large, the length of the packaging cavity can be effectively reduced, thereby reducing processing costs.

[0024] In this embodiment, a waveguide input end corner 2 and a waveguide output end corner 14 are provided at the input port of the input waveguide 1 and the output port of the output waveguide 15, so that the ports of the input waveguide and the output waveguide are located on the same horizontal line, and the cross-sectional area of ​​the waveguide at the corner is consistent with the cross-sectional area of ​​the input and output waveguide ports, both of which are WR4 waveguide standards, and the curvature of the corner bending can be optimized to achieve the best. In addition, an input height reduction chamfer 3 is provided at one end of the input waveguide 1 close to the input probe 5, and an output height reduction chamfer 13 is provided at one end of the output waveguide 15 close to the output probe 12, thereby forming a waveguide narrower than the WR4 waveguide standard. The height reduction chamfer is used for impedance matching, which can reduce the transmission loss of the signal and expand the bandwidth of the packaging module.

[0025] In this embodiment, the top of the input probe 5 and the output probe 12 are 20-30um away from the cavity wall, and the input probe transition structure quartz substrate 4 and the output probe transition structure quartz substrate 11 are 15um away from the cavity wall. The thickness of the input probe 5 and the output probe 12 is 1um, the thickness of the input suspension microstrip matching circuit 6 and the output suspension microstrip matching circuit 10 is 1um, and the thickness of the input probe transition structure quartz substrate 4 and the output probe transition structure quartz substrate 11 is 50um.

[0026] The simulation test results of this embodiment are as follows Figure 3 As shown, the results show that when the frequency band is 183GHz-218GHz, the insertion loss is less than 0.7dB.

[0027] The present invention adopts an undercut structure to enable precise processing, ensure the reliability of processing, reduce errors, and thus reduce insertion loss. The probe to chip adopts a suspended microstrip matching circuit for transition and matching, which can match impedance, expand bandwidth, and facilitate fixing to the cavity with conductive glue. At the same time, the chamfering of the input and output waveguides can further expand the bandwidth.

[0028] The above description is only a preferred implementation manner of the present invention, but the protection scope of the present invention is not limited thereto, and any modification and replacement based on the technical solution and inventive concept provided by the present invention should be included in the protection scope of the present invention.

Claims

1. A terahertz chip packaging structure based on suspended microstrip buckle, characterized in that: include: An upper cavity, a lower cavity, an input probe transition structure, a chip and an output probe transition structure. The upper cavity covers the lower cavity to form an input waveguide, an output waveguide and a cavity for placing the input probe transition structure, the chip and the output probe transition structure. The input probe transition structure includes an input probe, an input suspension microstrip matching circuit and an input probe transition structure quartz substrate. The input probe is connected to the input suspension microstrip matching circuit and is located on the input probe transition structure quartz substrate. The output probe transition structure includes an output probe, an output suspension microstrip matching circuit and an output probe transition structure quartz substrate. The output probe is connected to the output suspension microstrip matching circuit and is located on the output probe transition structure quartz substrate. The chip is connected to the input suspension microstrip matching circuit and the output suspension microstrip matching circuit. Electromagnetic waves are input through the input waveguide, and are output from the output waveguide after passing through the input probe transition structure, the chip and the output probe transition structure. A waveguide input end corner and a waveguide output end corner are provided at the input port of the input waveguide and the output port of the output waveguide, so that the ports of the input waveguide and the output waveguide are located on the same horizontal line. The chip includes a chip SiC substrate, an engraved metal block and a 50-ohm transmission line. The input probe transition structure quartz substrate and the output probe transition structure quartz substrate are both inverted on top of the chip SiC substrate. The input suspension microstrip matching circuit and the output suspension microstrip matching circuit are both connected to the 50-ohm transmission line through conductive glue.

2. The terahertz chip packaging structure based on suspended microstrip buckle according to claim 1 is characterized in that: The input suspended microstrip matching circuit and the output suspended microstrip matching circuit adopt a high-low impedance transmission line structure.

3. The terahertz chip packaging structure based on suspended microstrip buckle according to claim 1 is characterized in that: The input waveguide and the output waveguide are provided with a reduced height portion near the probe end.

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