Semiconductor devices and hybrid structures for ultra-wideband terahertz generation and reception

Abstract

An ultra-wideband hybrid structure (100) for transmitting high-frequency electrical signals, wherein the structure comprises a substrate (110), a high-speed semiconductor substrate (105) connected to the substrate (110) of the ultra-wideband structure (100), a conductive interface (115) set between the substrate (110) and the high-speed semiconductor substrate (105), an ultra-high-speed device set on the high-speed semiconductor substrate (105) defining a first access port (P1), a dielectric waveguide structure (DRW) defining a second access port (P2), a dielectric waveguide structure (DRW) set on the substrate (110) and the high-speed semiconductor substrate (105) and including a tapered end connectable to the first access port (P1) of the ultra-high-speed device, and a metal waveguide structure (TSA) providing a low-pass characteristic interconnection, a metal waveguide structure (TSA) set on the substrate (110) and the high-speed semiconductor substrate (105), wherein the metal waveguide structure (TSA) is a high-speed circuit or It includes a metal waveguide pattern defining a tapered coupler connected to the access port (P1) of the component.

Description

Technology Field

[0001] The present invention relates to a novel structure that enables the generation and detection of an ultra-wideband radio-frequency signal using a semiconductor device having two distinct features: first, the structure of the semiconductor material is formed to form a radio frequency (RF) waveguide; and second, the structure is the result of hybrid integration of a small die of III-V semiconductor material for an active device generating RF and part of an emitting antenna, and a larger silicon material for the remaining antenna and other passive RF components. Background Technology

[0002] The terahertz system operates in a spectral range including frequency bands between 0.1 and 10 THz, which is between the microwave and optical frequency bands. Various technologies for generating and detecting terahertz signals require components integrated into a die (an unpackaged bare chip), which can be electronic or photonic. Photonic-based systems require optoelectronic converters, and the active components of these systems are the most common ultrafast photodiodes (primarily PIN photodiodes, PIN-PDs, and uni-traveling-carrier photodiodes, UTC-PDs) and low-temperature-grown photoconductive antenna (LTG-PCA) photomixers, which are fabricated using III-V semiconductor compound alloys. Additionally, Gunn diodes, IMPATT diodes, resonant-tunneling diodes (RTDs), and varactor-Schottky diodes are commonly used. There are a wide range of electronic-based components, such as varactor Schottky diode multipliers, which generate high frequencies from a microwave reference source into higher-order harmonics.

[0003] The most commonly used semiconductor material substrate for manufacturing photonic and electronic devices is indium phosphide (InP), which is a III-V semiconductor compound that achieves the highest operating frequency and is therefore the preferred substrate for terahertz systems. However, the main disadvantages of this material are that it is very brittle and expensive.

[0004] These characteristics significantly affect the dimensions of the die chip, and particularly for terahertz generation and reception devices, it is desirable to integrate RF antennas with a larger footprint (millimeter size range) in addition to the components (micrometer size range). The substrate dimensions must be a minimum size (> 0.5 x 0.2 mm) to allow the device to be handled during the assembly process. 2 It cannot be smaller than ) and, due to the fragility of this material, it is not recommended to be larger than the maximum size (< 12mm x 6mm). Chips with dimensions outside these boundaries are, of course, possible, but at the cost of significantly high assembly costs and low yields. Due to these limitations, for systems operating in the low-frequency bands of the spectrum (i.e., the microwave range of 3GHz to 30GHz or the millimeter wave range of 30GHz to 300GHz), the die chip area is not sufficient to monolithically integrate an antenna onto the substrate used for the component.

[0005] One current approach to assembling a chip die and an antenna is illustrated in FIG. 1, which shows a 3D model of an assembly (50) comprising an optical fiber aligned to the optical input of an ultrafast photodiode (PD chip), wherein the electrical contact pad of the ultrafast photodiode excites a planar tapered-slot antenna (TSA) through a microwave access port (excitation port 1). In particular, FIG. 1 shows InP(ε r Manufactured in = 12.4) and 110RT / Duroid 5880 low dielectric constant substrate (ε r = 2.2) shows a high-speed photodiode device connected to a TSA type antenna manufactured. The size of the antenna hinders integration on an InP substrate, which is realized on a suitable RF substrate, and the electrical interconnection between the ultra-high-speed photodiode and the antenna becomes very important, especially as the desired operating frequency range is extended to higher frequency bands.

[0006] Among the various interconnection technologies currently available, the most common in the electronics industry is gold wire bonding. Fig. 2 shows a photograph of an InP-integrated ultra-high-speed photodiode chip (200), where electrical contact pads are connected to the access port of an antenna via gold wire bonding. However, the partially relaxed gold wire series parasitic inductance using two bonding wires per connection indicates a limit to the maximum operating frequency.

[0007] An additional challenge in the interconnection between the component die chip and the antenna RF substrate is the difference in dielectric constant between the substrates. Die chips with a higher refractive index generate reflections at this interface, which is particularly detrimental to high-frequency signals. These reflections mean that a portion of the signal returns to the emitting device, reducing the efficiency of the transmitter module.

[0008] The present invention overcomes the aforementioned limitations and disadvantages.

[0009] The present invention provides a solution that utilizes the full bandwidth of an ultra-wideband antenna driven by an ultra-high-speed semiconductor device, thereby enabling the combination of various substrates and overcoming the current limitations of available electrical interconnects that limit the bandwidth of terahertz and sub-terahertz systems.

[0010] Accordingly, the present invention presents a novel structure for ultra-high-speed devices based on a hybrid dielectric-conductor guide operating from DC to at least 300 GHz. The present invention proposes an ultra-wideband hybrid structure optimized for high-frequency electrical signals that can operate up to 340 GHz and can be designed to reach higher frequencies by changing the thickness and / or dielectric constant of the substrate. The ultra-wideband structure enables the coupling of high-frequency signals in high-speed circuits or components fabricated on high-speed semiconductor substrates (e.g., indium phosphide), the size of such components may be limited for technical, manufacturing, or handling reasons (i.e., size constraints make it impossible to integrate large components such as antennas, such as broadband waveguides or tapered bifilar metal waveguides). The ultra-wideband structure solves these problems and enables high-performance emission for high-frequency signals. Therefore, the ultra-wideband structure according to the present invention enables most signals to be combined in a single mode for all frequencies within the operating bandwidth, as shown in FIGS. 4a to 4d.

[0011] The main aspects of the hybrid structure according to the present invention are as follows:

[0012] A dielectric waveguide excited in the single-mode region for coupling signals from / to component die chips in the high-frequency band. This dielectric waveguide structure includes high-pass filter characteristics and a low cutoff frequency (f CLEnables electrical interconnection for signals having frequencies exceeding ). A dielectric waveguide comprising a tapered end facing an access port (P1) of an ultra-high speed semiconductor device (electronic or optoelectronic) manufactured on a high dielectric constant substrate (e.g., indium phosphide) split into a die chip. For example, the dielectric waveguide structure has a low cutoff frequency (f) in the microwave range (i.e., 3 GHz to 30 GHz) or the millimeter wave range (i.e., 30 GHz to 300 GHz). CL It can be designed to operate at an operating frequency of 60 GHz, including a wide frequency range extending beyond the terahertz range (i.e., 300 to 3000 GHz), starting from a range starting from ). The dielectric waveguide structure can be built on a substrate (110) and a high-speed semiconductor substrate, and the structure includes a tapered end facing a first access port of the ultra-high-speed device.

[0013] The hybrid structure according to the present invention also includes a metal waveguide structure having low-pass filter characteristics capable of establishing metal electrical contact with an access port of an ultra-high-speed device, thereby enabling the interconnected operating frequency range to start at a low frequency (i.e., preferably DC, starting at 0 Hz). This allows for a high cutoff frequency (f) in the millimeter wave range from 0 Hz. CH Electrical interconnection of signals up to ) is possible. For example, a metal waveguide structure can be designed to operate in a range extending from 0 Hz to the millimeter wave range (i.e., 30 GHz to 300 GHz, for example, an operating frequency of 100 GHz). In a preferred embodiment for broadband operation, this metal waveguide structure starts at a low frequency (i.e., DC, starting from 0 Hz) and the low cutoff frequency (f) of the dielectric waveguide structure CH > f CL It operates in a frequency range that extends above, for example, 60GHz (exceeding the previous example).

[0014] A metal waveguide structure can be constructed on a substrate and a high-speed semiconductor substrate, and the metal waveguide structure includes a metal waveguide pattern connected to a first access port (P1) of an ultra-high-speed device, which defines a tapered coupler, preferably a tapered slot antenna "TSA," around a tapered end of a dielectric waveguide structure.

[0015] The hybrid structure according to the present invention further includes electrical connections at low frequencies, which can be created through various techniques (e.g., bonding or conductive epoxy) that allow for less restrictive requirements in both spatial and electrical precision. The hybrid structure allows for ultra-wideband interconnection of electrical signals between substrates of the same or different dielectric constants at high frequencies, where variations in the substrates are important due to the introduction of discontinuities. High-frequency signal reflection is reduced by bridging said discontinuities, for example, by using conductive epoxy to couple the signal to the dielectric waveguide structure.

[0016] The hybrid structure according to the present invention may further include an ultra-high speed device structured such that the semiconductor material of the chip die relaxes the surface mode and forms an RF waveguide that maximizes RF power transfer between the ultra-high speed device and the metal waveguide structure at the contact pad. The semiconductor structure is formed during manufacturing through an additional process of chemical etchin (wet etching) on ​​the substrate of the ultra-high speed device in a single additional lithography step. Brief explanation of the drawing

[0017] For the sole purpose of better understanding the above description and providing examples, several non-limiting drawings schematically depicting actual embodiments are included. FIGS. 1 and FIGS. 2 show embodiments of the prior art. FIGS. 3a to 3d show four different embodiments of a hybrid structure according to the present invention. Figures 4a to 4d show simulated electric field amplitude distributions at 10 GHz (a), 60 GHz (b), 140 GHz (c) and 300 GHz (d), respectively. Figures 5a and 5b show the S parameters obtained from the performed simulation. Figures 6a and 6b show the interconnection of ultra-high speed devices fabricated on a high dielectric constant substrate on different substrates having a rectangular shape or a shape that fits a metal pattern with the same or different dielectric constants. Specific details for implementing the invention

[0018] FIG. 3a illustrates an example of an electrical interconnection according to the present invention, and in particular, this figure illustrates an ultra-wideband hybrid structure (100) for high-frequency electrical signals. The structure (100) includes a high-speed semiconductor substrate (105) (e.g., indium phosphide "InP", but not limited thereto) and an ultra-high-speed device on the substrate (110) and an electrical interconnection (115) set at a dividing point between the substrate (110) and the high-speed semiconductor substrate (105). The dividing point may be selected at a location where the hybrid structure (100) does not degrade signal transmission in the electrical interconnection due to frequency.

[0019] The high-speed semiconductor substrate (105) includes an ultra-high-speed device for generating or detecting high-frequency signals (i.e., in the millimeter wave and terahertz wave range). The electrical contact pads of this ultra-high-speed device define an access port (P1) in which the antenna is monolithically defined through its corresponding metallization features. Due to the limitations of the dimensions of the high-speed semiconductor substrate (105) (e.g., indium phosphide), this metallization is not large enough for the antenna to cover the entire frequency range and is limited to operating above the cutoff frequency. However, because the antenna is monolithically integrated into the high-speed semiconductor substrate (105), the interface between the ultra-high-speed device and the antenna is optimized to operate at ultra-high frequencies. As an example, FIG. 3a shows an edge-illuminated photomixer device, which is an ultra-high-speed device (i.e., a waveguide access photodiode), being illuminated through an optical fiber (130).

[0020] Additionally, the ultra-wideband hybrid structure (100) includes an optical waveguide (125) between the optical fiber (130) and the waveguide access photodiode when the optical fiber (130) provides edge optical illumination.

[0021] The substrate (110) is a substrate that allows for a larger size (e.g., RF substrates such as quartz, laminate, and ceramic, or silicon, etc.), and larger metallic features corresponding to a TSA antenna or a bipilar metal waveguide can be set. The larger features of the antenna enable operation in a frequency range that extends from the cutoff frequency of the ultra-high-speed device antenna of the high-speed semiconductor substrate (105) to lower frequencies.

[0022] The above substrate (110) is positioned next to the high-speed semiconductor substrate (105) to combine the metallization corresponding to the TSA antenna of each substrate, which is interconnected by electrical interconnects (115), such as bonding or conductive epoxy. The electrical interconnects (115) avoid the impact on the performance of the structure (100) at high frequencies and obtain an effective connection with low insertion loss. Thus, both reflection and excitation of surface waves are mitigated.

[0023] The above structure (100) also includes a second access port (P2) and a low cutoff frequency (f) in the microwave range or millimeter wave range. CL It includes a dielectric waveguide structure (DRW) that provides high-pass characteristic interconnects operating in a high-frequency range, starting from ). The structure (DRW) is set on a substrate (110) and a high-speed semiconductor substrate (105), and the structure (DRW) includes a tapered end facing or connected to an access port (P1) of an ultra-high-speed device.

[0024] The above structure (100) also includes a bipilar metal waveguide structure (TSA) providing low-pass characteristic interconnection, and the structure (TSA) set on the substrate (110) and the high-speed semiconductor substrate (105) has a high cutoff frequency (f) in the DC to millimeter wave range. CH It operates in a low frequency range up to ). The bipilar metal waveguide structure (TSA) is a tapered structure, that is, it includes a metal waveguide pattern defining a tapered slot antenna “TSA” around the tapered end of a tapered coupler, preferably a dielectric waveguide structure (DRW), and is located in close proximity to the access port (P1) of the ultra-high speed device.

[0025] A tapered bipillar metal waveguide structure (TSA) is set between a high-speed semiconductor substrate (105) and a substrate (110), and a greater feature of the tapered bipillar metal waveguide is manufactured. By dividing the tapered bipillar metal waveguide structure (TSA) between the substrate (110) and the high-speed semiconductor substrate (105), high frequencies are coupled to a dielectric waveguide (DRW) before reaching an electrical interconnection (115) between the substrate (110) and the high-speed semiconductor substrate (105), for example, through a conductive epoxy, thereby preventing reflection.

[0026] If the dividing point between the substrate (110) and the high-speed semiconductor substrate (105) is appropriately selected, each includes a complementary portion of the tapered bipilar metal waveguide structure (TSA), and the electrical interconnection between the corresponding metallization of the tapered bipilar metal waveguide structure (TSA) of each substrate (105, 110) does not interfere with the high frequency already coupled to the dielectric waveguide structure (DRW).

[0027] The above structure (100) also preferably includes a second dielectric structure (120), which is a pyramidal structure etched into a high-speed semiconductor substrate (105). In some examples, the pyramidal structure is a horn structure that can be set on one or both of the substrates (105, 110) and mitigates surface waves.

[0028] Accordingly, FIGS. 3a through 3d illustrate an electrical interconnection (115) established between two substrates (105, 110) of an ultra-high-speed device (electronic or optoelectronic) fabricated on a high-speed semiconductor substrate (105), for example, an interconnection to another substrate (110) that may have the same or different dielectric constant having epoxy. Various embodiments of the structure (100) include both horizontal (edge) (Figs. 3a and 3c) and vertical (Figs. 3b and 3d) illumination using an optical fiber (130).

[0029] To mitigate the surface mode of the ultra-high speed device substrate, a second dielectric structure (120), preferably a pyramidal structure, can be etched onto the high speed semiconductor substrate (105) (Figs. 3c and 3d). This increases the amount of combined signal in the basic mode of the dielectric waveguide (DRW), making it possible to fill in the discontinuity caused by bonding of the substrate with almost no reflection.

[0030] FIGS. 4a through 4d show simulated electric field amplitude distributions at 10 GHz (Fig. 4a), 60 GHz (Fig. 4b), 140 GHz (Fig. 4c), and 300 GHz (Fig. 4d) for a horizontal illumination photodiode (Fig. 4a, Fig. 4b, and Fig. 4e) connected to an alumina substrate (Al2O3, εr = 9.8) with substrate InP (logarithmic amplitude scale). In the simulation, most of the signal is shown traveling between access ports (P1) and (P2) in a single mode at each frequency. As illustrated, at higher frequencies (Figs. B, C, and D), the signal is coupled from the antenna (TSA) (operating as a near-field coupler) to the silicon (DRW) tapered end. Since this coupling occurs near the photodiode, far from the discontinuity of the substrate (105, 110), signal reflection is reduced.

[0031] FIGS. 5a and 5b show the S parameters obtained from the simulations performed as shown in FIGS. 4a through 4d. Due to the discontinuity caused by the transition between the substrates (105, 110), reflections may occur as shown in FIG. 5a, but signal transmission is possible up to at least 340 GHz (assuming a -3 dB level at S12 and S21). To mitigate these reflections, the edges of the high-speed semiconductor substrate (105) to which the ultra-high-speed device is connected can be wrapped around the (TSA) (Fig. 6b). As can be seen in the S parameters shown in FIG. 5b, reflections are suppressed, and the ripple level of the S parameters is reduced.

[0032] FIG. 6a shows another example of an ultra-wideband hybrid structure (100) for high-frequency electrical signals, comprising an interconnection between an ultra-high-speed device and a substrate (110) for generating or detecting high-frequency signals on a high-speed semiconductor substrate (105) having a high dielectric constant (e.g., indium phosphide "InP", but not limited thereto), and an electrical interconnection (115) between them.

[0033] In this particular example, the substrate (110) includes a rectangular shape that is easy to cut. The substrate (110) is a substrate that allows for a larger size (i.e., RF substrates such as quartz, laminate, and ceramic, or silicon, etc.), which can establish larger metallization features corresponding to a TSA antenna or a bipilar metal waveguide.

[0034] Additionally, FIG. 6a also shows an ultra-high speed device including an edge-illuminating photomixer device (i.e., a waveguide access photodiode) that is illuminated through an optical fiber (130).

[0035] Due to the discontinuity created by the transition between the substrates (105, 110), reflection may occur, as illustrated in FIG. 5a. To mitigate this reflection, the edge of the substrate (110) can be wrapped around the (TSA). In this regard, FIG. 6b shows an ultra-high speed device manufactured or set on a high dielectric constant substrate being interconnected to another substrate (110) having a shape that is aligned with or tapered to the metal pattern (TSA). FIG. 6b also shows an ultra-high speed device comprising an optical fiber (130) and a second dielectric structure (120), preferably an edge-illuminating photomixer device (i.e., waveguide access photodiode) which is a pyramidal structure etched into the high-speed semiconductor substrate (105).

Claims

Claim 1 An ultra-wideband hybrid structure (100) for transmitting or receiving a high-frequency electrical signal, comprising: - a substrate (110); - a high-speed semiconductor substrate (105) connected to the substrate (110); - an electrical interconnection (115) established between the substrate (110) and the high-speed semiconductor substrate (105); - an ultra-high-speed device for generating or detecting a high-frequency signal established on the high-speed semiconductor substrate (105), comprising a first access port (P1); - a low cutoff frequency (f) of a microwave range or a millimeter-wave range. CL A dielectric waveguide structure (DRW) comprising a second access port (P2) providing a high-pass characteristic interconnection operating over a high-frequency range starting from ), configured on the substrate (110) and the high-speed semiconductor substrate (105), and comprising a tapered end facing the first access port (P1) of the ultra-high-speed device, a high cutoff frequency (f) in the millimeter wave range at DC. CH An ultra-wideband hybrid structure (100) for high-frequency electrical signals comprising a metal waveguide structure (TSA) providing low-pass characteristic interconnection operating over a low-frequency range up to, wherein the metal waveguide structure (TSA) is established on the substrate (110) and the high-speed semiconductor substrate (105), and the metal waveguide structure (TSA) comprises a metal waveguide pattern defining a tapered coupler around the tapered end of the dielectric waveguide structure (DRW) and connected to a first access port (P1) of the ultra-high-speed device. Claim 2 In claim 1, the substrate (110) has a rectangular shape and is an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 3 In claim 1, the substrate (110) has a tapered shape in the shape of the metal waveguide structure (TSA), an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 4 An ultra-wideband hybrid structure (100) for high-frequency electrical signals, further comprising a tapered structure (120) etched on the high-speed semiconductor substrate (105) and / or the substrate (110) in any one of claims 1 to 3. Claim 5 In claim 4, the tapered structure (120) is a horn structure, an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 6 In claim 1, the ultra-high speed device is an optoelectronic device, an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 7 In claim 6, an ultra-wideband hybrid structure (100) for high-frequency electrical signals further comprising an optical fiber (130) that provides edge optical illumination or vertical optical illumination to the optoelectronic device. Claim 8 In claim 6, the optoelectronic device is a high-speed photodiode or a photoconductive antenna, an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 9 In claim 8, an ultra-wideband hybrid structure (100) for high-frequency electrical signals further comprising an optical waveguide (125) between the optical fiber (130) and the high-speed photodiode or the photoconductive antenna when the optical fiber (130) provides edge optical illumination. Claim 10 In claim 1, the ultra-wideband hybrid structure (100) for high-frequency electrical signals, wherein the ultra-high-speed device is an electronic device. Claim 11 In claim 1, the high-speed semiconductor substrate (105) comprises a III-V compound semiconductor such as indium phosphide, gallium nitride, gallium arsenide, InAlAs / InGaAs or AlGaN / GaN, an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 12 In claim 1, the electrical interconnection (115) comprises wire bonding, ribbon bonding, flip-chip bonding, or epoxy, an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 13 In claim 1, the substrate (110) comprises an RF substrate such as quartz, laminate, ceramic, or silicon, an ultra-wideband hybrid structure (100) for high-frequency electrical signals. Claim 14 In claim 1, the metal waveguide structure (TSA) is a tapered slot antenna, an ultra-wideband hybrid structure (100) for high-frequency electrical signals.

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