2.5d / 3d optoelectronic co-packaging device based on electro-absorption modulator and preparation method thereof

Abstract

This invention relates to a 2.5D / 3D optoelectronic co-packaged device based on an electro-absorption modulator and its fabrication method, including a germanium-silicon electro-absorption modulator (1). This invention achieves a high-speed, high-bandwidth, and small-volume 2.5D / 3D optical engine for optical I / O using a TSV active silicon interposer board through optical interconnect architecture design for high-performance computing, expansion of single-fiber channel count using wavelength division multiplexing (WDM) technology, design of a high-performance germanium-silicon electro-absorption modulator that operates stably under multiple wavelengths, and development of an active interposer board process with high-quality selective epitaxial growth of single-crystal germanium-silicon material.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, and specifically relates to a 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator and its fabrication method. Background Technology

[0002] With the rapid development of emerging businesses such as cloud computing, ChatGPT, and artificial intelligence (AI), the demand for high-performance computing data transmission and processing has increased dramatically. Optical interconnect (optical I / O) has emerged as a response, utilizing optical connections to achieve interconnection between computing chips. It boasts advantages such as ultra-high bandwidth, ultra-fast transmission rates, and high anti-interference capabilities. Effective signal interconnection is required between photonic integrated circuits (PICs) chips, electronic integrated circuits (EICs) chips, and packaging substrates / printed circuit boards (PCBs) forming this optical interconnect architecture. 3D packaging solutions integrate EICs and PICs through three-dimensional stacking. The EICs and PICs are connected via micro-bumps, and the PICs are interconnected to the PCB via wire bonding, or TSVs are directly formed within the PICs and interconnected directly to the substrate. In this case, the PIC also acts as an adapter board. This solution further improves integration and reliability. Therefore, 2.5D / 3D packaging solutions based on TSVs and adapter boards are the most competitive advanced packaging technologies for optical I / O. In addition, for the PIC portion, most companies use micro-ring modulators and drivers as the signal generation end for optical interconnects. These are small in size and low in power consumption, but have a narrow operating wavelength range and are highly sensitive to temperature changes, requiring complex temperature feedback control circuitry, making them quite challenging. Germanium-silicon detectors also offer advantages in size and low power consumption, and their operating wavelength range is wider than that of micro-ring modulators. Using electro-absorption modulators while simultaneously expanding the number of channels per fiber through wavelength division multiplexing (WDM) technology provides a new approach to optical I / O.

[0003] The 2.5D packaging structure and its fabrication method disclosed in CN117908200A connects the electrical chip and the optical chip via a substrate, resulting in a large interconnection length and high loss between the optoelectronic chips. Therefore, a new packaging structure and its fabrication method are needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a 2.5D / 3D optoelectronic co-packaging device based on an electro-absorption modulator and its fabrication method. The device uses a germanium-silicon electro-absorption modulator and a germanium detector as the core devices for transmission and reception, and introduces wavelength division multiplexing technology to improve the capacity of a single optical fiber and realize multi-channel parallel transmission.

[0005] This invention provides a 2.5D / 3D optoelectronic co-packaging device based on an electro-absorption modulator, including a germanium-silicon electro-absorption modulator; the germanium-silicon electro-absorption modulator includes a silicon substrate and a silicon dioxide upper cladding layer on the silicon substrate; a ridge waveguide located on and covered by the silicon dioxide upper cladding layer; a middle ridge waveguide is provided in the middle of the ridge waveguide; a P-type lightly doped silicon region and an N-type lightly doped silicon region are provided in the middle of the middle ridge waveguide, and a P-type heavily doped silicon region and an N-type heavily doped silicon region are located at both ends of the middle ridge waveguide; a groove is provided in the middle of the P-type lightly doped silicon region and the N-type lightly doped silicon region, and a silicon-germanium waveguide is provided in the middle of the groove, as well as a P-type lightly doped silicon region and an N-type lightly doped silicon region at both ends of the silicon-germanium waveguide; a TiN heater and a SiN waveguide are provided above the middle ridge waveguide.

[0006] Preferably, the P-type silicon heavily doped region, the N-type silicon heavily doped region, and the TiN heater are all connected to metal electrodes.

[0007] Preferably, the germanium-silicon electroabsorption modulator is further provided with silicon through-holes on both the left and right sides.

[0008] Preferably, the through-silicon via is deposited with microbumps.

[0009] Furthermore, the germanium-silicon electroabsorption modulator is provided with passivation protective layers on both the upper and lower sides.

[0010] Furthermore, an RDL layer is provided between the germanium-silicon electroabsorption modulator and the passivation protection layer.

[0011] Furthermore, the middle part of the germanium-silicon electroabsorption modulator also includes a blocking layer.

[0012] The present invention also provides a method for fabricating a 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator, comprising the following steps:

[0013] (1) First, etching is performed on the SOI substrate, and the top silicon layer is etched into a ridge waveguide. The ridge waveguide is doped with p-Si, n-Si, p++-Si and n++-Si by ion implantation. Grooves are etched in the doped ridge waveguide, and silicon-germanium waveguides are epitaxially grown in the grooves by depressurized chemical vapor deposition and polished by chemical mechanical polishing. Then, P-type light doped regions of germanium-silicon and N-type light doped regions of germanium-silicon are doped in the silicon-germanium waveguide, respectively. Finally, a silicon dioxide cladding is covered and a TiN heater and a SiN waveguide are prepared to obtain a germanium-silicon electro-absorption modulator.

[0014] (2) The obtained germanium-silicon electroabsorption modulator is etched with silicon dioxide dielectric, and then TSV via etching, oxide dielectric passivation layer, barrier layer and seed layer deposition, TSV electroplating and planarization, via etching of different metal layers, TSV and front RDL layer electroplating, front microbump electroplating, temporary bonding, substrate thinning, back TSV exposure, back RDL layer electroplating, back microbump process and debonding process are performed in sequence to obtain a 2.5D / 3D optoelectronic co-packaged device based on electroabsorption modulator.

[0015] The present invention also provides an application of a 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator in optical interconnects.

[0016] Beneficial effects

[0017] (1) This invention achieves a high-speed, high-bandwidth, and small-volume TSV active silicon interposer 2.5D / 3D optical engine for optical I / O by designing an optical interconnect architecture for high-performance computing, using wavelength division multiplexing technology to broaden the number of single fiber channels, designing a high-performance germanium-silicon electroabsorption modulator that works stably under multiple wavelengths, and developing an active interposer board process with high-quality selective epitaxial growth of single-crystal germanium-silicon materials.

[0018] (2) The present invention proposes a technical solution that combines germanium-silicon electroabsorption modulator with TSV advanced packaging technology, which has the advantages of small size and low power consumption, thus facilitating the realization of a small-sized and highly integrated optical engine.

[0019] (3) This invention proposes to use a differentially driven differential germanium-silicon electroabsorption modulator to further suppress common-mode noise and interference.

[0020] (4) The present invention uses a germanium-silicon electroabsorption modulator with an integrated on-chip TiN heater to broaden the operating wavelength range, realize multi-channel transmission through wavelength division multiplexing technology, and achieve stable operation of the germanium-silicon electroabsorption modulator under multiple wavelengths through the feedback control circuit in the chip.

[0021] (5) The 2.5D / 3D packaging scheme proposed in this invention has a higher integration level. The electrical chip is directly flip-chip bonded to the optical chip and then connected to the substrate through TSV to achieve short-distance interconnection. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the electroabsorption modulator of the present invention.

[0023] Figure 2 This is a schematic diagram of the 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator according to the present invention.

[0024] Figure 3This is a schematic diagram of the fabrication process of the electroabsorption modulator of the present invention.

[0025] Figure 4 This is a schematic diagram of the fabrication process of the 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator according to the present invention. Detailed Implementation

[0026] 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.

[0027] Example 1

[0028] Depend on Figure 1 As shown, this embodiment provides a 2.5D / 3D optoelectronic co-packaging device based on an electro-absorption modulator, including a germanium-silicon electro-absorption modulator 1. The germanium-silicon electro-absorption modulator 1 is the core device of this invention, and its working principle is the FK effect, that is, under the action of an external electric field, the free carrier concentration of electron-hole pairs changes, thereby changing the absorption characteristics of the material and ultimately reflecting a change in light intensity.

[0029] The germanium-silicon electroabsorption modulator 1 includes a silicon substrate 101 and a silicon dioxide upper cladding 102 located on the silicon substrate 101; a ridge waveguide 112 located on and covered by the silicon dioxide upper cladding 102; an intermediate ridge waveguide 112-1 located in the middle of the ridge waveguide 112; a P-type lightly doped silicon region 103 and an N-type lightly doped silicon region 104 located in the middle of the intermediate ridge waveguide 112-1; and a region located in the intermediate ridge waveguide 112-1. The waveguide 112-1 has a P-type heavily doped silicon region 105 and an N-type heavily doped silicon region 106 at both ends; the P-type lightly doped silicon region 103 and the N-type lightly doped silicon region 104 are provided with a groove in the middle, and a silicon-germanium waveguide 107 is provided in the middle of the groove, as well as a P-type germanium-silicon lightly doped region 108 and an N-type germanium-silicon lightly doped region 109 at both ends of the silicon-germanium waveguide 107; a TiN heater 110 and a SiN waveguide 111 are provided above the intermediate ridge waveguide 112-1.

[0030] Preferably, the P-type silicon heavily doped region 105, the N-type silicon heavily doped region 106, and the TiN heater 110 are all connected to metal electrodes 2.

[0031] like Figure 2As shown, the germanium-silicon electroabsorption modulator 1 also has through-silicon vias 3 on both the left and right sides. Microbumps 7 are deposited on the through-silicon vias 3. Passivation protection layers 6 are also provided on the upper and lower sides of the germanium-silicon electroabsorption modulator 1. An RDL layer 4 is provided between the germanium-silicon electroabsorption modulator 1 and the passivation protection layer 6. A barrier layer 5 is also included in the middle of the germanium-silicon electroabsorption modulator 1.

[0032] This embodiment also provides a method for fabricating a 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator, comprising the following steps:

[0033] (1) As Figure 3 As shown, firstly, etching is performed on the SOI substrate, and the top silicon layer is etched into a ridge waveguide 112. The ridge waveguide 112 is then doped with p-Si, n-Si, p++-Si, and n++-Si using ion implantation. Grooves are etched into the doped ridge waveguide 112, and silicon-germanium waveguides 107 are epitaxially grown at the grooves using reduced pressure chemical vapor deposition, followed by chemical mechanical polishing. Then, p-type lightly doped regions 108 and N-type lightly doped regions 109 are doped into the silicon-germanium waveguide 107, respectively. Finally, a silicon dioxide cladding is applied, and a TiN heater 110 and a SiN waveguide 111 are fabricated to obtain the silicon-germanium electro-absorption modulator 1.

[0034] (2) Figure 4 As shown, the obtained germanium-silicon electroabsorption modulator 1 is etched with silicon dioxide dielectric, followed by TSV via etching, oxide dielectric passivation layer, barrier layer and seed layer deposition, TSV electroplating and planarization, via etching of different metal layers, TSV and front RDL layer electroplating, front microbump electroplating, temporary bonding, substrate thinning, back TSV exposure, back RDL layer electroplating, back microbump process and debonding process to obtain a 2.5D / 3D optoelectronic co-packaged device based on electroabsorption modulator.

Claims

1. A 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator, characterized in that: The device includes a germanium-silicon electroabsorption modulator (1); the germanium-silicon electroabsorption modulator (1) includes a silicon substrate (101), a silicon dioxide upper cladding (102) located on the silicon substrate (101); a ridge waveguide (112) located on and covered by the silicon dioxide upper cladding (102); a middle ridge waveguide (112-1) is provided in the middle of the ridge waveguide (112-1); a P-type lightly doped silicon region (103) and an N-type lightly doped silicon region (104) are provided in the middle of the middle ridge waveguide (112-1), and The intermediate ridge waveguide (112-1) has a P-type silicon heavily doped region (105) and an N-type silicon heavily doped region (106) at both ends; the P-type silicon lightly doped region (103) and the N-type silicon lightly doped region (104) are provided with a groove in the middle, and a silicon-germanium waveguide (107) is provided in the middle of the groove, as well as a P-type germanium-silicon lightly doped region (108) and an N-type germanium-silicon lightly doped region (109) at both ends of the silicon-germanium waveguide (107); a TiN heater (110) and a SiN waveguide (111) are provided above the intermediate ridge waveguide (112-1).

2. The 2.5D / 3D optoelectronic co-packaging device according to claim 1, characterized in that: The P-type silicon heavily doped region (105), N-type silicon heavily doped region (106), and TiN heater (110) are all connected to metal electrodes (2).

3. The 2.5D / 3D optoelectronic co-packaging device according to claim 1, characterized in that: The germanium-silicon electroabsorption modulator (1) is also provided with silicon through-holes (3) on both the left and right sides.

4. The 2.5D / 3D optoelectronic co-packaging device according to claim 3, characterized in that: The through-silicon via (3) has microbumps (7) deposited on it.

5. The 2.5D / 3D optoelectronic co-packaging device according to claim 1, characterized in that: The germanium-silicon electroabsorption modulator (1) is also provided with passivation protective layers (6) on the upper and lower sides.

6. The 2.5D / 3D optoelectronic co-packaging device according to claim 5, characterized in that: An RDL layer (4) is provided between the germanium-silicon electroabsorption modulator (1) and the passivation protection layer (6).

7. The 2.5D / 3D optoelectronic co-packaging device according to claim 1, characterized in that: The germanium-silicon electroabsorption modulator (1) also includes a barrier layer (5) in the middle.

8. An application of a 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator as described in any one of claims 1-7 in optical interconnects.

9. A method for fabricating a 2.5D / 3D optoelectronic co-packaging device based on an electroabsorption modulator as described in any one of claims 1-7, comprising the following steps: (1) First, etching is performed on the SOI substrate, and the top silicon layer is etched into a ridge waveguide (112). The ridge waveguide (112) is doped with p-Si, n-Si, p++-Si and n++-Si by ion implantation. Grooves are etched in the doped ridge waveguide (112), and silicon-germanium waveguide (107) is epitaxially grown in the groove by depressurized chemical vapor deposition and polished by chemical mechanical polishing. Then, p-type light doped region (108) and N-type light doped region (109) of germanium-silicon are doped in the silicon-germanium waveguide (107), respectively. Finally, a silicon dioxide cladding is covered and a TiN heater (110) and a SiN waveguide (111) are prepared to obtain a germanium-silicon electro-absorption modulator (1). (2) The obtained germanium-silicon electroabsorption modulator (1) is etched with silicon dioxide dielectric, and then TSV via etching, oxide dielectric passivation layer, barrier layer and seed layer deposition, TSV electroplating and planarization, via etching of different metal layers, TSV and front RDL layer electroplating, front microbump electroplating, temporary bonding, substrate thinning, back TSV exposure, back RDL layer electroplating, back microbump process and debonding process are performed to obtain a 2.5D / 3D optoelectronic co-packaged device based on electroabsorption modulator.

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