A multi-layer heat dissipation packaging structure and method for a high-power terahertz laser chip

Abstract

The application relates to a high-power terahertz laser chip multilayer heat dissipation packaging structure and a packaging method, the packaging structure comprising a multilayer THz QCL unit; the THz QCL unit comprising, in sequence, a surface circuit, a first heat-conducting medium, an electrode layer, a lower contact layer, a THz QCL substrate, THz QCL back gold and a second heat-conducting medium; the electrode layer comprising a THz QCL active region arranged in the middle and an upper electrode, and lower electrode steps and a lower electrode arranged at two ends, the upper electrode and the lower electrode being close to the side of the first heat-conducting medium; and the multilayer THz QCL unit forming a THz QCL array. The application sets a heat-conducting module above the THz QCL, increases an upper heat dissipation channel, expands the heat-conducting path and the heat dissipation area of the THz QCL, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of terahertz quantum cascade laser technology, and specifically relates to a multi-layer heat dissipation packaging structure and packaging method for a high-power terahertz laser chip. Background Technology

[0002] Terahertz quantum cascade lasers (THz QCLs) are important solid-state terahertz sources with broad application prospects in terahertz imaging, local oscillation sources, non-destructive testing, and precision spectral analysis. Ridge-type end-face emission structures are a type of waveguide structure for THz QCLs that offers high reliability and output power. Traditional packaging methods primarily involve attaching the ridge blocks to a gold-plated copper heat sink using thermally conductive indium foil. During operation, heat can only be transferred to the heat sink through the substrate at the bottom of the chip. Since the THz QCL substrate is made of semi-insulating GaAs material with relatively low thermal conductivity, the heat dissipation effect is limited. Array packaging of multiple THz QCLs with narrow ridges is an effective heat dissipation method, but traditional packaging methods only extend the array in one dimension. Therefore, there is an urgent need for a multilayer structure that can rapidly dissipate heat from THz QCLs. By optimizing the THz QCL array arrangement, heat dissipation at the bottom and top of the device can be improved, enabling higher power output from the THz QCL. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a multi-layer heat dissipation packaging structure and packaging method for a high-power terahertz laser chip. The packaging structure is designed with an end-face emitting THz QCL array in a two-dimensional direction to increase the total output power of the device, and adopts a dual heat sink structure design to expand the heat dissipation area of ​​the device, which is beneficial to the overall heat dissipation of the device.

[0004] This invention provides a multilayer heat dissipation packaging structure for a high-power terahertz laser chip. The packaging structure includes multiple THz QCL units. Each THz QCL unit sequentially includes a surface circuit, a first thermally conductive medium, an electrode layer, a lower contact layer, a THz QCL substrate, and a THz QCL back gold layer. The electrode layer includes a THz QCL active region and an upper electrode disposed in the middle, and a lower electrode step and a lower electrode disposed at both ends. The upper electrode and the lower electrode are located near the side of the first thermally conductive medium. The multiple THz QCL units form a THz QCL array.

[0005] Preferably, the surface circuit is composed of a diamond heat sink or a diamond film.

[0006] Preferably, the first thermally conductive medium is an indium sheet.

[0007] Preferably, the lower electrode step raises the lower electrode to the same horizontal height as the upper electrode.

[0008] Preferably, the THz QCL unit is surrounded by a second heat-conducting medium, a diamond backing, and a diamond heat sink.

[0009] Preferably, the THz QCL units are separated by a diamond film.

[0010] Preferably, a gold-plated ceramic sheet is adhered to the diamond heat sink; a power supply lead is constructed between the gold-plated ceramic sheet and the surface circuit.

[0011] The present invention also provides a multi-layer heat dissipation packaging method for a high-power terahertz laser chip, comprising the following steps:

[0012] S1. A strip window is prepared on a superlattice epitaxial wafer for THz QCL by photolithography, and an upper electrode is prepared on the epitaxial wafer by magnetron sputtering. After sputtering, excess photoresist is removed.

[0013] S2. The THz QCL active region and lower electrode step are fabricated on the epitaxial wafer by photolithography and etching. After etching, excess photoresist is removed.

[0014] S3. A strip window is prepared on the epitaxial wafer by photolithography, and a lower electrode is prepared on the epitaxial wafer by electron beam evaporation. After the evaporation is completed, excess photoresist is removed.

[0015] S4. Anneal the epitaxial wafer;

[0016] S5. Thinning and polishing the epitaxial substrate to obtain the THz QCL substrate;

[0017] S6. THz QCL back gold is grown on the back of the epitaxial wafer using magnetron sputtering;

[0018] S7. A strip window is prepared on a diamond thin film and a diamond heat sink by photolithography, and a surface circuit is prepared on a diamond thin film and a diamond heat sink by magnetron sputtering.

[0019] S8. After removing the adhesive, a strip window is prepared on the diamond film and diamond heat sink by photolithography, and a first thermally conductive medium is grown on the diamond film and diamond heat sink.

[0020] S9. A THz QCL unit is flip-chip soldered onto the circuit of a diamond heat sink using a pick-and-place machine; the side of the diamond film without sputtered circuit is attached to the back of the THz QCL unit, and the structure is further fixed using low-temperature adhesive.

[0021] S10. Another THz QCL unit is flip-chip soldered onto the diamond thin film circuit using a pick-and-place machine to construct a second THz QCL array.

[0022] S11. A gold-plated ceramic sheet is attached to a diamond heat sink, and a power supply lead is constructed between the ceramic sheet and the diamond thin film circuit using a wire bonding machine.

[0023] S12. Using a second thermally conductive medium, attach a diamond backing and a diamond heat sink to the back of the final layer chip to obtain the final layer chip.

[0024] Beneficial effects

[0025] This invention combines a THz QCL fabrication method with a different approach, altering the traditional wire bonding method and utilizing a diamond heat sink as a circuit board. This constructs a THz QCL array that can expand in two dimensions. The integration of THz QCL units in more dimensions increases the overall output power of the device. Simultaneously, the packaging structure with diamond heat sinks soldered to both the top and bottom of the THz QCL chip provides each chip with two heat dissipation channels (top and bottom), offering a vertical heat dissipation path and expanding the heat conduction path and heat dissipation area. This changes the traditional single heat dissipation path of THz QCL chips, which relies solely on the bottom heat sink. This optimized heat dissipation method facilitates the rapid dissipation of the large amount of heat generated during the operation of the multi-layer THz QCL array, reducing the impact of heat accumulation on the THz QCL output power and enabling higher power output. Attached Figure Description

[0026] Figure 1 This is a front view of the packaging structure of the present invention.

[0027] Figure 2 This is a top view of the surface circuit in this invention.

[0028] Figure 3 This is a side view of the packaging structure of the present invention.

[0029] In the figure: 1. Surface circuit; 2. First thermally conductive medium; 3. Electrode layer; 31. THz QCL active region; 32. Upper electrode; 33. Lower electrode step; 34. Lower electrode; 4. Lower contact layer; 5. THz QCL substrate; 6. THz QCL back gold; 7. Second thermally conductive medium; 8. Diamond back gold; 9. Diamond heat sink; 10. Diamond film; 11. Power supply wire; 12. Gold-plated ceramic sheet. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0031] Example 1

[0032] Depend on Figures 1-3 As shown, this embodiment provides a multilayer heat dissipation packaging structure for a high-power terahertz laser chip. The packaging structure includes multiple THz QCL units. Each THz QCL unit sequentially includes a surface circuit, a first thermally conductive medium, an electrode layer, a lower contact layer, a THz QCL substrate, and a THz QCL back gold layer. The electrode layer includes a THz QCL active region and an upper electrode disposed in the middle, and a lower electrode step and a lower electrode disposed at both ends. The upper electrode and the lower electrode are located near the side of the first thermally conductive medium. The multiple THz QCL units form a THz QCL array.

[0033] Preferably, the surface circuit is composed of a diamond heat sink or a diamond film.

[0034] Preferably, the first thermally conductive medium is an indium sheet.

[0035] Preferably, the lower electrode step raises the lower electrode to the same horizontal height as the upper electrode.

[0036] Preferably, the THz QCL unit is surrounded by a second heat-conducting medium, a diamond backing, and a diamond heat sink.

[0037] Preferably, the THz QCL units are separated by a diamond film.

[0038] Preferably, a gold-plated ceramic sheet is adhered to the diamond heat sink; a power supply lead is constructed between the gold-plated ceramic sheet and the surface circuit.

[0039] This embodiment also provides a multi-layer heat dissipation packaging method for a high-power terahertz laser chip, including the following steps:

[0040] S1. A strip window is formed on a superlattice epitaxial wafer for THz QCL by photolithography. Ti / Au metal top electrodes with thicknesses of 25 nm and 400 nm are formed on the epitaxial wafer by magnetron sputtering. After sputtering, excess photoresist is removed.

[0041] S2. The THz QCL active region and lower electrode step are fabricated on the epitaxial wafer by photolithography and etching. After etching, excess photoresist is removed.

[0042] S3. A strip window is fabricated on the epitaxial wafer by photolithography, and Ge / Au / Ni / Au metal lower electrodes with thicknesses of 13 nm, 33 nm, 30 nm and 400 nm are fabricated on the epitaxial wafer by electron beam evaporation. After the evaporation is completed, excess photoresist is removed.

[0043] S4. Anneal the epitaxial wafer;

[0044] S5. Thinning and polishing the epitaxial substrate to obtain the THz QCL substrate;

[0045] S6. Ti / Au THz QCL back gold with thicknesses of 10 nm and 200 nm were grown on the back of the epitaxial wafer by magnetron sputtering.

[0046] S7. A strip window is prepared on a diamond thin film and a diamond heat sink by photolithography, and a surface circuit is prepared on a diamond thin film and a diamond heat sink by magnetron sputtering.

[0047] S8. After removing the resist, a strip window is prepared on the diamond film and diamond heat sink by photolithography, and an indium pillar is grown on the diamond film and diamond heat sink.

[0048] S9. A THz QCL unit is flip-chip soldered onto the circuit of a diamond heat sink using a pick-and-place machine; the side of the diamond film without sputtered circuit is attached to the back of the THz QCL unit, and the structure is further fixed using low-temperature adhesive.

[0049] S10. Another THz QCL unit is flip-chip soldered onto the diamond film circuit using a chip mounter to construct a second THz QCL array. This structure can be used to construct multiple THz QCLs according to the above steps, realizing the expansion of THz QCLs in the two-dimensional direction and further improving the total output power of THz QCLs.

[0050] S11. A gold-plated ceramic sheet is attached to a diamond heat sink, and a power supply lead is constructed between the ceramic sheet and the diamond thin film circuit using a wire bonding machine.

[0051] S12. Using indium pillars, diamond backing and diamond heat sink are attached to the back of the last layer chip to achieve double-layer heat dissipation of THz QCL and expand the heat diffusion area of ​​THz QCL.

Claims

1. A multi-layer heat dissipation packaging structure for a high-power terahertz laser chip, characterized in that, The packaging structure includes a multilayer THz QCL unit; the THz QCL unit sequentially includes a surface circuit, a first thermally conductive medium, an electrode layer, a lower contact layer, a THz QCL substrate, and a THz QCL back gold layer; the electrode layer includes a THz QCL active region and an upper electrode disposed in the middle, and a lower electrode step and a lower electrode disposed at both ends, the upper electrode and the lower electrode being close to the side of the first thermally conductive medium; the multilayer THz QCL units form a THz QCL array.

2. The multi-layer heat dissipation packaging structure for high-power terahertz laser chips according to claim 1, characterized in that, The surface circuit is composed of a diamond heat sink or a diamond film.

3. The multi-layer heat dissipation packaging structure for high-power terahertz laser chips according to claim 1, characterized in that, The first thermally conductive medium is an indium sheet.

4. The multi-layer heat dissipation packaging structure for a high-power terahertz laser chip according to claim 1, characterized in that, The lower electrode step raises the lower electrode to the same horizontal height as the upper electrode.

5. The multi-layer heat dissipation packaging structure for a high-power terahertz laser chip according to claim 1, characterized in that, The THz QCL unit is surrounded by a second heat-conducting medium, a diamond backing, and a diamond heat sink.

6. The multi-layer heat dissipation packaging structure for a high-power terahertz laser chip according to claim 1, characterized in that, The THz QCL units are separated by a diamond film.

7. The multi-layer heat dissipation packaging structure for a high-power terahertz laser chip according to claim 1, characterized in that, A gold-plated ceramic sheet is adhered to the diamond heat sink; a power supply lead is constructed between the gold-plated ceramic sheet and the surface circuit.

8. A multi-layer heat dissipation packaging method for a high-power terahertz laser chip, characterized in that, Includes the following steps: S1. A strip window is prepared on a superlattice epitaxial wafer for THz QCL by photolithography. An upper electrode is prepared on the epitaxial wafer by magnetron sputtering. After sputtering, excess photoresist is removed. S2. The THz QCL active region and lower electrode step are fabricated on the epitaxial wafer by photolithography and etching. After etching, excess photoresist is removed. S3. A strip window is prepared on the epitaxial wafer by photolithography, and a lower electrode is prepared on the epitaxial wafer by electron beam evaporation. After the evaporation is completed, excess photoresist is removed. S4. Anneal the epitaxial wafer; S5. Thinning and polishing the epitaxial substrate to obtain the THz QCL substrate; S6. THz QCL back gold is grown on the back of the epitaxial wafer using magnetron sputtering; S7. A strip window is prepared on a diamond film and a diamond heat sink by photolithography, and a surface circuit is prepared on the diamond film and the diamond heat sink by magnetron sputtering. S8. After removing the adhesive, a strip window is prepared on the diamond film and diamond heat sink by photolithography, and a first thermally conductive medium is grown on the diamond film and diamond heat sink. S9. A THz QCL unit is flip-chip soldered onto the circuit of a diamond heat sink using a pick-and-place machine; the side of the diamond film without sputtered circuit is attached to the back of the THz QCL unit, and the structure is further fixed using low-temperature adhesive. S10. Another THz QCL unit is flip-chip soldered onto the diamond film circuit using a pick-and-place machine to construct a second THz QCL array, and the structure is further fixed using low-temperature adhesive. S11. A gold-plated ceramic sheet is attached to a diamond heat sink, and a power supply lead is constructed between the ceramic sheet and the diamond thin film circuit using a wire bonding machine. S12. Using a second thermally conductive medium, attach a diamond backing and a diamond heat sink to the back of the final layer chip to obtain the final layer chip.

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