A novel electro-optic modulator in a silicon photonics system

Abstract

The application relates to the field of semiconductor technology, in particular to a novel electro-optic modulator in a silicon photonics system, which comprises an integrated optical path with a silicon wafer; a silicon dioxide layer is arranged on the silicon wafer on the integrated optical path by semiconductor process technology; a P-type silicon layer is arranged on the silicon oxide layer by epitaxial process on the integrated optical path by semiconductor process technology; a silicon germanium layer doped with P-type carriers is arranged on the P-type silicon layer by epitaxial process on the integrated optical path by semiconductor process technology; an intermediate insulating layer is arranged on the silicon germanium layer on the integrated optical path by semiconductor process technology; a strained silicon nitride layer is arranged on the intermediate insulating layer on the integrated optical path by semiconductor process technology; an N-type silicon layer is arranged on the strained silicon nitride layer by epitaxial process on the integrated optical path by semiconductor process technology; and the strained silicon nitride layer and the silicon germanium layer doped with P-type carriers can enhance the change of refractive index to enhance the phase modulation of light waves.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a novel electro-optic modulator in a silicon photonics system. Background Technology

[0002] Silicon photonics, or SiPH, is designed and manufactured using semiconductor processes, encompassing integrated circuit (EIC) and integrated optical circuit (PIC) components. It is an essential component for next-generation microwave communications, massive data centers, and high-speed AI computing. In silicon photonics devices, the electro-optic modulator modulates phase and amplitude by changing the optical refractive index and absorption coefficient through a driving voltage within a silicon waveguide.

[0003] Plasma dispersion effect is often used in high-speed silicon modulators. The refractive index change effect induced by plasma dispersion is shown in formula ①: ∆n=-(e 2 λ 2 / 8π 2 c 2 ε0n)[∆N e / m* ce +∆N h / m* ch ① Where e is the electron charge, ε0 is the dielectric constant in vacuum, c is the speed of light in vacuum, λ is the wavelength, n is the unperturbed refractive index, and m* ce and m* ch ∆N represents the effective mass of electrons and holes, representing their conductivity. e and ∆N h The change in the concentration of electrons and holes is due to the following drawbacks of existing electro-optic modulators: the change in refractive index is too small for the phase modulation amplitude of the light wave to be significant enough. Therefore, a novel design is proposed to improve the above problems. Summary of the Invention

[0004] To overcome the shortcomings mentioned above, the present invention aims to provide a novel design for an electro-optic modulator used in SiPH, thereby solving the problems mentioned in the background art.

[0005] Since the plasma dispersion effect is inversely proportional to the effective mass, a strain engineering method to reduce the effective mass of electrons and holes is proposed, namely, designing a novel electro-optic modulator in a silicon photonics system, including an integrated optical path with a silicon wafer on the integrated optical path; In the integrated optical path, a silicon dioxide layer is deposited on a silicon wafer using semiconductor manufacturing technology; In the integrated optical path, a P-type silicon layer is set on the silicon oxide layer using an epitaxial process with semiconductor process technology. In the integrated optical path, a germanium silicide layer doped with P-type carriers is set on a P-type silicon layer using an epitaxial process with semiconductor process technology. In the integrated optical path, an intermediate insulating layer is set on the germanium silicide layer using semiconductor process technology; In the integrated optical path, a strained silicon nitride layer is formed on the intermediate insulating layer using semiconductor process technology; In the integrated optical path, an N-type silicon layer is set on the strained silicon nitride layer using an epitaxial process with semiconductor process technology. In the integrated optical path, a polycrystalline silicon layer is set on an N-type silicon layer using semiconductor process technology; In this process, the P-type silicon layer and the N-type silicon layer are used as optical waveguides. In the integrated optical path, a bias voltage is applied to the P-type silicon layer and the N-type silicon layer to change their refractive index.

[0006] Preferably, the intermediate insulating layer has a sandwich structure and is made of silicon oxide, aluminum oxide, zirconium oxide or hafnium oxide.

[0007] Preferably, both the P-type silicon layer and the polycrystalline silicon layer extend with electrical contacts, and the bias voltage is electrically connected to the electrical contacts.

[0008] Preferably, the thickness of the silicon dioxide layer is 120nm-200nm.

[0009] Preferably, the thickness of the P-type silicon layer is 100nm-200nm.

[0010] Preferably, the thickness of the germanium silicide layer is 10nm-25nm.

[0011] Preferably, the thickness of the intermediate insulating layer is 2nm-10nm.

[0012] Preferably, the thickness of the strained silicon nitride layer is 8nm-20nm.

[0013] Preferably, the thickness of the N-type silicon layer is 100nm-200nm.

[0014] Preferably, the thickness of the polycrystalline silicon layer is 100nm-200nm.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention proposes a novel structural design for an electro-optic modulator. A p-type carrier-doped germanium silicide layer is epitaxially fabricated on a p-type silicon layer. The germanium silicide layer is an epitaxial structure with a saturation value for Ge content; if this value is too high, diastereomeric growth will be impossible. Utilizing the fact that Ge atoms are larger than Si atoms, lattice stretching occurs, resulting in greater stress than in pure p-type silicon atoms. Therefore, strain forces act on the p-type silicon layer, reducing the effective mass of holes. Similarly, an n-type silicon layer is epitaxially fabricated on a strained silicon nitride layer. The strained silicon nitride layer also acts on the n-type silicon layer, reducing the effective mass of electrons. This further enhances the refractive index of the n-type silicon layer. Therefore, the strained silicon nitride layer and the strained p-type carrier-doped germanium silicide layer will further enhance the refractive index change, thereby enhancing the phase modulation of the light wave.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is the spectrum of the present invention; Figure 3 This is a graph showing the relationship between the optical transmission rate and wavelength of this invention; Figure 4 This is a phase change diagram caused by the refractive index of this invention.

[0019] The reference numerals and names in the figure are as follows: Silicon wafer 100, silicon dioxide layer 200, P-type silicon layer 300, germanium silicide layer 400, intermediate insulating layer 500, strained silicon nitride layer 600, N-type silicon layer 700, polycrystalline silicon layer 800, and electrical connection part 900. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1In this embodiment of the invention, a novel electro-optic modulator in a silicon photonics system includes an integrated optical path, the setup of which includes the following steps: S1. An integrated optical path is provided with a silicon wafer 100 as the substrate; S2. Using semiconductor process technology, a silicon dioxide layer 200 is disposed on a silicon wafer 100 in the integrated optical path; S3. Using semiconductor process technology, a P-type silicon layer 300 is set on the silicon oxide layer using an epitaxial process in the integrated optical path; S4. Using semiconductor process technology, a germanium silicide layer 400 doped with P-type carriers is set on the P-type silicon layer 300 using an epitaxial process on the integrated optical path. S5. Using semiconductor process technology, an intermediate insulating layer 500 is set on the germanium silicide layer 400 in the integrated optical path; S6. Using semiconductor process technology, a strained silicon nitride layer 600 is formed on the intermediate insulating layer 500 in the integrated optical path. S7. Using semiconductor process technology, an N-type silicon layer 700 is formed on the strained silicon nitride layer 600 by epitaxial process in the integrated optical path. S8. Using semiconductor process technology, a polysilicon layer 800 is disposed on the N-type silicon layer 700 in the integrated optical path; Among them, the P-type silicon layer 300 and the N-type silicon layer 700 are used as optical waveguides. In the integrated optical path, a bias voltage is applied to the P-type silicon layer 300 and the N-type silicon layer 700 to change the refractive index of the P-type silicon layer 300 and the N-type silicon layer 700.

[0022] Please see Figure 1 The intermediate insulating layer 500 has a sandwich structure and is made of silicon oxide, aluminum oxide, zirconium oxide or hafnium oxide. Both the P-type silicon layer 300 and the polycrystalline silicon layer 800 extend with a grounding portion 900, and the bias voltage is electrically connected to the grounding portion 900. The thickness of the silicon dioxide layer 200 is 120nm-200nm; the thickness of the P-type silicon layer 300 is 100nm-200nm; the thickness of the germanium silicide layer 400 is 10nm-25nm; the thickness of the intermediate insulating layer 500 is 2nm-10nm; the thickness of the strained silicon nitride layer 600 is 8nm-20nm; the thickness of the N-type silicon layer 700 is 100nm-200nm; and the thickness of the polycrystalline silicon layer 800 is 100nm-200nm.

[0023] Please see Figure 2-4This invention proposes a novel structural design for an electro-optic modulator. A p-type carrier-doped germanium silicide layer 400 is formed on a p-type silicon layer 300 using an epitaxial process. The germanium silicide layer 400 is an epitaxial structure with a saturation value for Ge content. If the content is too high, the diatomic structure cannot grow. By utilizing the fact that Ge atoms are larger than Si atoms, lattice stretching occurs, and the stress is greater than that of pure p-type silicon atoms. Therefore, there will be strain forces acting on the p-type silicon layer, reducing the effective mass of holes.

[0024] Similarly, an N-type silicon layer 700 is formed on the strained silicon nitride layer 600 using an epitaxial process; the strained silicon nitride layer 600 will exert strain on the N-type silicon layer 700, reducing the effective mass of electrons. According to formula ①: ∆n=-(e 2 λ 2 / 8π 2 c 2 ε0n)[∆N e / m* ce +∆N h / m* ch ① Where e is the electron charge, ε0 is the dielectric constant in vacuum, c is the speed of light in vacuum, λ is the wavelength, n is the unperturbed refractive index, and m* ce and m* ch ∆N represents the effective mass of electrons and holes, representing their conductivity. e and ∆N h This represents the change in the concentration of electrons and holes; like Figure 3 and Figure 4 As shown, Figure 3 This is a graph showing the relationship between optical transmission rate and wavelength. Figure 4 The diagram shows the phase change caused by refractive index; this will further enhance the refractive index of the N-type silicon layer 700 and the strained P-type carrier-doped germanium silicide layer 400; therefore, the strained silicon nitride layer 600 and the strained P-type carrier-doped germanium silicide layer 400 will further enhance the change in refractive index to enhance the phase modulation of the light wave.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A novel electro-optic modulator in a silicon photonics system, characterized in that, Includes integrated optical circuitry, which contains silicon wafers; In the integrated optical path, a silicon dioxide layer is deposited on a silicon wafer using semiconductor manufacturing technology; In the integrated optical path, a P-type silicon layer is set on the silicon oxide layer using an epitaxial process with semiconductor process technology. In the integrated optical path, a germanium silicide layer doped with P-type carriers is set on a P-type silicon layer using an epitaxial process with semiconductor process technology. In the integrated optical path, an intermediate insulating layer is set on the germanium silicide layer using semiconductor process technology; In the integrated optical path, a strained silicon nitride layer is formed on the intermediate insulating layer using semiconductor process technology; In the integrated optical path, an N-type silicon layer is set on the strained silicon nitride layer using an epitaxial process with semiconductor process technology. In the integrated optical path, a polycrystalline silicon layer is set on an N-type silicon layer using semiconductor process technology; In this process, the P-type silicon layer and the N-type silicon layer are used as optical waveguides. In the integrated optical path, a bias voltage is applied to the P-type silicon layer and the N-type silicon layer to change their refractive index.

2. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The intermediate insulating layer has a sandwich structure and is made of silicon oxide, aluminum oxide, zirconium oxide or hafnium oxide.

3. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, Both the P-type silicon layer and the polysilicon layer have extensions with electrical contacts, and the bias voltage is electrically connected to the electrical contacts.

4. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The thickness of the silicon dioxide layer is 120nm-200nm.

5. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The thickness of the P-type silicon layer is 100nm-200nm.

6. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The thickness of the germanium silicide layer is 10nm-25nm.

7. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The thickness of the intermediate insulating layer is 2nm-10nm.

8. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The thickness of the strained silicon nitride layer is 8nm-20nm.

9. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The thickness of the N-type silicon layer is 100nm-200nm.

10. A novel electro-optic modulator in a silicon photonics system according to claim 1, characterized in that, The thickness of the polycrystalline silicon layer is 100nm-200nm.

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