Manufacturing Method of GaN Terahertz Monolithic Circuit and Die with Cantilever Beam Structure

Abstract

The present invention relates to the field of semiconductor manufacturing technology, and specifically relates to a manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure, the GaN terahertz monolithic circuit and die with a cantilever beam structure, including: a substrate, GaN located on the substrate, devices located on the GaN, a metal layer circuit located on the substrate, and a cantilever beam located on the GaN; The present invention is fully compatible with various current mainstream GaN microwave power devices and MMIC processes. By etching specific areas of the substrate and GaN, most areas of the circuit are separated from the wafer, and finally, the terahertz monolithic circuit and die are completely separated from the wafer by combining with the traditional dicing process, forming the cantilever beam structure and avoiding damage to the cantilever beam caused by the dicing process, enabling the GaN terahertz monolithic circuit and die with a cantilever beam structure to have the ability of large-scale mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a method for manufacturing a GaN terahertz monolithic circuit and a tube core with a cantilever beam structure. Background Art

[0002] Signal transmission in the terahertz band is a major obstacle to the development of terahertz technology. The use of traditional planar dielectric microstrip lines easily leads to significant dispersion and transmission loss. While new transmission methods such as rectangular waveguides, dielectric slot waveguides, or hollow dielectric waveguides can address these loss and dispersion issues, they hinder the integration of microwave RF circuits. Suspended microstrip, on the other hand, offers improved dispersion characteristics and a higher Q value than currently used planar dielectric microstrip lines. Furthermore, it facilitates integrated circuit fabrication and has already found successful engineering applications in terahertz frequency multiplication and mixing.

[0003] To minimize dielectric loss and dispersion, suspended microstrip circuits typically keep dielectric thickness within tens of microns. This results in mechanical fragility, making the dielectric susceptible to cracking during assembly due to handling. Suspended microstrip circuits with cantilever beams effectively address this issue. The cantilever beams support the circuit and load electrical signals, preventing direct stress on the dielectric film during assembly and improving assembly yield.

[0004] Terahertz frequency-doubling circuits fabricated from GaN materials have attracted widespread attention in recent years due to their high power handling capabilities. Fabricating GaN terahertz thin-film integrated circuits with cantilever beams has high practical value. Traditionally, thin-film circuits are manufactured by removing the semiconductor material surrounding the circuit chip through etching or corrosion, followed by separation from the wafer by immersion in an organic solution. However, this traditional method results in the thin-film circuit separating from the wafer in a disordered manner, hindering subsequent cleaning and sampling, and making it unsuitable for large-scale manufacturing. Summary of the Invention

[0005] To solve the above problems, the present invention provides a method for manufacturing a GaN terahertz monolithic circuit and die with a cantilever beam structure. The method uses etching of the substrate and GaN in specific areas to separate most areas of the circuit from the wafer. Finally, the terahertz monolithic circuit and die are completely separated from the wafer in combination with a traditional scribing process, thereby forming a cantilever beam structure while avoiding damage to the cantilever beam caused by the scribing process. This enables the GaN terahertz monolithic circuit and die with a cantilever beam structure to be capable of large-scale batch production.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a manufacturing method for a GaN terahertz monolithic circuit and die with a cantilever beam structure. The GaN terahertz monolithic circuit and die with a cantilever beam structure include: a substrate, GaN located on the substrate, devices located on the GaN, a metal layer circuit located on the substrate, and a cantilever beam located on the GaN. The manufacturing method includes the following steps:

[0008] S1. Prepare various integrated devices on the epitaxial wafer composed of GaN and the substrate;

[0009] S2. Etch away the GaN material in a specific area;

[0010] S3. Form the required circuit on the substrate;

[0011] S4. Bond the epitaxial wafer and the substrate together;

[0012] S5. Grind the back surface of the substrate to reduce the thickness of the substrate;

[0013] S6. Etch away part of the substrate to expose the GaN in a specific area;

[0014] S7. Remove the barrier layer to expose the cantilever beam metal;

[0015] S8. Separate the GaN epitaxial wafer and the substrate;

[0016] S9. After dicing, obtain a GaN terahertz monolithic circuit and die with a cantilever beam structure.

[0017] The present invention is further configured as: the substrate is any one of SiC, Al2O3, or diamond.

[0018] The present invention is further configured as: the GaN is GaN or different combinations of GaN and its ternary compounds, including different combinations of AlGaN or InGaN and GaN.

[0019] The present invention is further configured as: the device is a GaN active device or other integrated passive devices.

[0020] The present invention is further configured as: the circuit is formed on the substrate and connected to the device.

[0021] The present invention is further configured as: one end of the cantilever beam is formed and fixed on the GaN, and the other end is suspended. The number of cantilever beams can be increased according to specific requirements, or can be connected to the circuit or device according to requirements to form a cantilever beam that plays a conduction role.

[0022] Adopting the technical solution provided by the present invention, compared with the known public technology, it has the following beneficial effects:

[0023] The present invention is fully compatible with various current mainstream GaN microwave power devices and MMIC processes. By etching the substrate and GaN in specific regions, most of the circuit is separated from the wafer. Finally, combined with the traditional dicing process, the terahertz monolithic circuit and die are completely separated from the wafer, forming a cantilever beam structure while also avoiding damage to the cantilever beam caused by the dicing process, enabling the GaN terahertz monolithic circuit and die with a cantilever beam structure to have the ability of large-scale mass production. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the present invention after the device is fabricated on the GaN epitaxial wafer;

[0025] Figure 2 It is a schematic diagram of the present invention after etching the GaN in specific regions;

[0026] Figure 3 It is a cross-sectional schematic diagram of the present invention after fabricating the microstrip circuit and the cantilever beam;

[0027] Figure 4 It is a top view of the present invention after fabricating the microstrip circuit and the cantilever beam;

[0028] Figure 5 It is a schematic diagram of the present invention after wafer bonding;

[0029] Figure 6 It is a schematic diagram of the present invention after etching the substrate material in specific regions;

[0030] Figure 7 It is a schematic diagram of the present invention after etching the GaN material in specific regions;

[0031] Figure 8 It is a schematic diagram of the present invention after wafer separation;

[0032] Figure 9 It is a top view of the present invention after wafer separation;

[0033] Figure 10 It is a schematic diagram of the GaN terahertz monolithic circuit and die with a cantilever beam structure after dicing in the present invention.

[0034] Explanation of the reference numerals in the figures:

[0035] 1. Substrate; 2. GaN; 3. Device; 4. Circuit; 5. Cantilever beam; 6. Bonding wax; 7. Substrate; 8. Dicing groove track. Detailed Embodiments

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top / bottom end", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements; for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0039] Embodiment:

[0040] As Figure 1-10 shown, the GaN terahertz monolithic circuit and die with a cantilever beam structure provided by the present invention include: a substrate 1, GaN 2 located on the substrate 1, a device 3 located on the GaN 2, a metal layer circuit 4 located on the substrate 1, and a cantilever beam 5 located on the GaN 2.

[0041] A manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure provided by the present invention includes the following steps:

[0042] (1) Prepare various integrated devices 3 on the epitaxial wafer composed of GaN 2 and the substrate 1.

[0043] Further, the substrate 1 is any one of SiC, Al2O3 or diamond.

[0044] Further, GaN 2 is GaN or different combinations of GaN and its ternary compounds, including different combinations of AlGaN or InGaN and GaN.

[0045] Further, the device 3 is a GaN active device or other integrated passive device.

[0046] In this step, it should be noted that as Figure 1 shown, the 0001 direction of GaN2 is perpendicular to the horizontal plane, which is a Ga-face polar material with a thickness between 200 nm and 5 μm.

[0047] (2) Etch away the GaN material in a specific area.

[0048] In this step, it should be noted that in the present invention, an etch stop layer is formed by photolithography, and the GaN material in a specific area is removed by Cl-based inductively coupled plasma etching, only leaving a part of GaN2 around the device 3 and the cantilever beam 5. The etch stop layer is a photoresist mask with a thickness between 6 μm and 12 μm. After etching, the remaining etch stop layer is removed. The result after etching the GaN in the specific area is as Figure 2 shown.

[0049] (3) Form the required circuit 4 on the substrate 1.

[0050] Further, the circuit 4 is formed on the substrate 1 and connected to the device 3.

[0051] Further, one end of the cantilever beam 5 is formed and fixed on the GaN2, and the other end is suspended. Moreover, the number of the cantilever beams 5 can be increased according to specific requirements, or it can be connected to the circuit 4 or the device 3 according to requirements to form a conductive cantilever beam 5.

[0052] In this step, it should be noted that a photoresist mask pattern is formed by photolithography to prepare the circuit 4 and the cantilever beam 5. Metal is formed at the photoresist mask pattern by evaporation or electroplating, and then the photoresist mask is removed by a lift-off process. The circuit 4 is formed on the substrate 1, and the cantilever beam 5 is formed on the GaN2. The thickness of the photoresist mask is between 6 μm and 12 μm, and the thickness of the circuit 4 and the cantilever beam 5 is between 0.5 μm and 6 μm. The circuit 4 is formed on the substrate 1, the circuit 4 is connected to the device 3, the cantilever beam 5 is formed on the GaN2, and the cantilever beam 5 can only be a support structure or can also serve as a power supply port according to requirements. The results after preparing the circuit 4 and the cantilever beam 5 are as Figure 3 and 4 shown.

[0053] (4) Bond the epitaxial wafer and the substrate 7 together.

[0054] In this step, it should be noted that bonding wax 6 is spin-coated on the entire front side of the epitaxial wafer and the epitaxial wafer is bonded to the substrate 7, which facilitates subsequent processing of the back side of the epitaxial wafer. The thickness of the bonding wax 6 is between 10 μm and 50 μm, and the thickness of the substrate 7 is between 300 μm and 1000 μm. The result after bonding is as shown in Figure 5 shown.

[0055] (5)Grind the back side of the substrate 1 to reduce the thickness of the substrate 1.

[0056] In this step, it should be noted that, as an implementation manner, in this application, the back side of the substrate 1 is ground by a diamond grinding wheel to reduce the thickness of the substrate 1.

[0057] (6)Etch away part of the substrate 1 to expose GaN2 in a specific area.

[0058] In this step, it should be noted that an etching barrier layer metal 8 is formed by an electroplating process, and then part of the substrate 1 is etched away to expose GaN2 in a specific area. A photoresist mask required for electroplating is formed by photolithography. After electroplating and removing the photoresist, the etching barrier layer metal 8 is formed. The thickness of the etching barrier layer metal 8 is between 4 μm and 10 μm. The substrate 1 is etched by an F-based inductively coupled plasma etching method, and the etching selectivity of the etching gas for the substrate 1 and GaN2 is greater than 10. After etching, the remaining etching barrier layer metal 8 is removed by a wet etching method. The result after substrate etching is as shown in Figure 6 shown.

[0059] (7)Remove the barrier layer to expose the metal of the cantilever beam 5.

[0060] In this step, it should be noted that, using the etched substrate 1 as an etching mask, the GaN2 material in specific areas such as under the cantilever beam is removed by a dry etching or wet etching method. The etching is carried out by a Cl-based inductively coupled plasma etching method; the wet etching is carried out by a hot phosphoric acid etching or KOH solution etching method. The physical and chemical processes of etching or corroding GaN2 need to ensure that there is no lateral etching or corrosion parallel to the wafer surface on the bonding wax 6, so as to prevent damage to the device 3. The result after etching or corroding GaN is as shown in Figure 7 shown.

[0061] (8)Separate the GaN epitaxial wafer from the substrate 7.

[0062] In this step, it should be noted that the GaN epitaxial wafer is separated from the substrate 7 and the residual bonding wax 6 is removed; the result after this step is as shown in Figure 8As shown, one end of the cantilever beam 5 is suspended in the air and the other end contacts GaN2 to play a fixing role. The two sides of the GaN terahertz monolithic circuit and die with the cantilever beam 5 are air, and the other two sides are connected to form a whole through the substrate 1.

[0063] (9) After scribing, a GaN terahertz monolithic circuit and die with a cantilever beam structure are obtained.

[0064] In this step, it should be noted that a GaN terahertz monolithic circuit and die with a cantilever beam structure are obtained. Based on the steps shown Figure 8 above, the wafer is scribed along the unetched scribing groove track 8 as shown in Figure 9 so that a single GaN terahertz monolithic circuit and die are changed from a whole into separate circuit chips. The diagram of the GaN terahertz monolithic circuit and die after scribing is as shown in Figure 10 the figure.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure, characterized in that, The GaN terahertz monolithic circuit and die with a cantilever beam structure include: a substrate (1), GaN (2) located on the substrate (1), a device (3) located on the GaN (2), a metal layer circuit (4) located on the substrate (1), and a cantilever beam (5) located on the GaN (2). Its manufacturing method includes the following steps: S1. Prepare various integrated devices (3) on the epitaxial wafer composed of GaN (2) and the substrate (1); S2. Etch away the GaN material in a specific area; S3. Form the required circuit (4) on the substrate (1); S4. Bond the epitaxial wafer and the substrate (7) together; S5. Grind the back surface of the substrate (1) to reduce the thickness of the substrate (1); S6. Etch away part of the substrate (1) to expose the GaN (2) in a specific area; S7. Remove the barrier layer to expose the metal of the cantilever beam (5); S8. Separate the GaN epitaxial wafer and the substrate (7); S9. After dicing, obtain the GaN terahertz monolithic circuit and die with a cantilever beam structure.

2. The manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure according to claim 1, wherein The substrate (1) is any one of SiC, Al2O3, or diamond.

3. The manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure according to claim 1, characterized in that, The GaN (2) is GaN or different combinations of GaN and its ternary compounds, including different combinations of AlGaN or InGaN and GaN.

4. The manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure according to claim 1, characterized in that The device (3) is a GaN active device or other integrated passive devices.

5. The manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure according to claim 1, characterized in that, The circuit (4) is formed on the substrate (1) and connected to the device (3).

6. The manufacturing method of a GaN terahertz monolithic circuit and die with a cantilever beam structure according to claim 1, characterized in that, One end of the cantilever beam (5) is formed and fixed on the GaN (2), and the other end is suspended. The number of cantilever beams (5) can be increased according to specific requirements, or can be connected to the circuit (4) or the device (3) according to requirements to form a cantilever beam (5) that plays a conduction role.

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