WO2021258583A1 - Doping structure of silicon-based electro-optic modulator - Google Patents

Abstract

A doping structure of a silicon-based electro-optic modulator, the doping structure comprising: a first doped region (2), a second doped region (3), a third doped region (4), and a fourth doped region (5); the first doped region (2) and the second doped region (3) have the same type of doping, the second doped region (3) and the third doped region (4) have opposite types of doping, and the third doped region (4) and the fourth doped region (5) have the same type of doping; the contact surfaces of the second doped region (3) and the third doped region (4) are staggered to form a periodic structure, and the periodic structure is adjusted by means of the amplitude of a microwave signal, thereby improving the modulation efficiency of the modulator.

Description

Silicon-based electro-optic modulator doped structure

Cross-references to related applications

This application is filed based on a Chinese patent application with an application number of 202010573470.2 and an application date of June 22, 2020, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby incorporated into this application by reference.

Technical field

The present invention relates to the field of semiconductor technology, in particular to a silicon-based electro-optic modulator doped structure.

Background technique

With the development trend of communication interconnection speed and cost reduction, a large number of communication and interconnection equipment is updated, data traffic has increased sharply, and the bandwidth requirements of switching nodes continue to increase. Traditional electrical interconnection equipment has gradually been unable to meet the requirements. Optical interconnection technology has gradually developed. Devices have been extensively studied in the fields of data exchange, data transmission, microwave signal processing and transmission, and optoelectronic CPUs.

Silicon photonics technology is a new generation technology based on silicon and silicon-based substrate materials (such as SiGe/Si, SOI, etc.), using the existing CMOS process for optical device development and integration, combined with the ultra-large scale and ultra-high precision of integrated circuit technology The characteristics of manufacturing and the advantages of photonic technology's ultra-high speed and ultra-low power consumption are disruptive technologies to deal with the failure of Moore's Law. Integrate microelectronics and optoelectronics on a silicon-based platform, and give full play to the advanced and mature microelectronics technology, low-cost prices brought by large-scale integration, and the extremely high bandwidth, ultra-fast transmission rate, and high-speed characteristics of photonic devices and systems. Anti-interference and other advantages have become the inevitable development of information technology and the general consensus of the industry.

At present, the silicon-based transceiver system has begun to be commercialized, but the system has high energy consumption, and the pressure on the communication and interconnection infrastructure has increased sharply. The modulator is an important component of the transceiver in the optical communication and optical interconnection system. Its energy consumption is second only to the laser, but the insertion loss of the modulator itself also increases the power budget, so it is an important research in the current efforts to reduce energy consumption. Object. Research on silicon-based electro-optic modulators has made great progress in recent years. It uses mature CMOS technology to achieve large-scale chip manufacturing, thereby effectively reducing chip manufacturing costs.

There are two main doping structures of traditional silicon-based electro-optic modulators: lateral PN junction and interdigitated PN junction. The modulation efficiency of the interdigital type is higher than that of the lateral type, but because it has periodic doping changes in the direction of light transmission, the transmission loss of the optical signal is larger. Although the lateral structure has low transmission loss for optical signals, the modulation efficiency is low, the device is longer, and the overall optical loss is difficult to meet the requirements.

These reflect the difficulty that the modulation efficiency, optical loss, and modulation rate of the current silicon-based integrated modulator cannot be achieved at the same time. Modulation efficiency and optical loss are both important performance indicators in a communication system. Higher modulation efficiency can reduce device size and drive voltage; lower optical transmission loss can reduce the complexity of the entire communication system. At the same time, a silicon-based integrated modulator that achieves high modulation efficiency, low optical loss, and high modulation rate is an urgent technical requirement for the next generation of transceiver technology.

The existing technology has the following disadvantages:

(1) The introduction of ion doping of different concentrations adds additional processes, and some processes are not compatible with standard CMOS processes;

(2) Although the periodic doping structure improves the modulation efficiency of the modulator, it also increases the loss of the device.

In summary, how to provide a silicon-based electro-optic modulator doping structure to overcome the difficulty of traditional silicon-based electro-optic modulators that are incompatible with modulation efficiency and modulation energy consumption, and to ensure that each doped area in the core area of the waveguide The electrical connection can be achieved directly through the lateral waveguide, which has become one of the technical problems to be solved urgently.

Summary of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

For this reason, the purpose of the present invention is to propose a silicon-based electro-optical modulator doped structure, which solves the problem of incompatibility of modulation efficiency and modulation energy consumption of traditional silicon-based electro-optical modulators.

To achieve the foregoing objective, an embodiment of the present invention proposes a silicon-based electro-optic modulator doping structure, including:

A first doped region, a second doped region, a third doped region, and a fourth doped region;

The doping type of the first doped region is the same as that of the second doped region, the doping type of the second doped region is opposite to that of the third doped region, and the third doped region is the same as that of the third doped region. The fourth doped region has the same doping type;

The contact surfaces of the second doped region and the third doped region are staggered to form a periodic structure, and the periodic structure is adjusted by the amplitude of the microwave signal.

The doped structure of the silicon-based electro-optic modulator of the embodiment of the present invention changes the change period of the doped pattern in the transmission direction of the optical waveguide in accordance with a certain physical law. Under the premise of not significantly increasing the length and optical loss of the modulator, the modulation efficiency of the modulator is significantly improved.

In addition, the silicon-based electro-optic modulator doped structure according to the foregoing embodiment of the present invention may also have the following additional technical features:

Further, in an embodiment of the present invention, the doping type of the first doped region and the second doped region is P-type, the first doped region is a P-type heavily doped region, so The second doped region is a P-type lightly doped region, and the first doped region is disposed above the second doped region;

The second doped region is arranged above the third doped region;

The third doped region and the fourth doped region have a doping type of N-type, the third doped region is an N-type lightly doped region, and the fourth doped region is an N-type heavily doped region. Region, the third doped region is arranged above the fourth doped region.

Further, in an embodiment of the present invention, the doping type of the first doped region and the second doped region is N-type, and the first doped region is an N-type heavily doped region, so The second doped region is an N-type lightly doped region, and the first doped region is disposed above the second doped region;

The second doped region is arranged above the third doped region;

The doping type of the third doped region and the fourth doped region is P-type, the third doped region is P-type lightly doped region, and the fourth doped region is P-type heavily doped Region, the third doped region is arranged above the fourth doped region.

Further, in an embodiment of the present invention, the periodic structure is a periodic structure with a rectangular distribution.

Further, in an embodiment of the present invention, the periodic structure is a periodic structure distributed in a zigzag shape.

Further, in an embodiment of the present invention, the periodic structure is a periodic structure of a trigonometric function change type.

Further, in an embodiment of the present invention, the amplitude of the microwave signal is inversely proportional to the contact area of the contact surface between the second doped region and the third doped region.

The additional aspects and advantages of the present invention will be partially given in the following description, and some will become obvious from the following description, or be understood through the practice of the present invention.

Description of the drawings

The above-mentioned and/or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of the doped structure of a silicon-based electro-optic modulator according to an embodiment of the present invention;

2 is a schematic diagram of the doped structure of a silicon-based electro-optic modulator according to a specific embodiment of the present invention;

3 is a schematic diagram of the doped structure of a silicon-based electro-optic modulator according to another specific embodiment of the present invention;

4 is a schematic diagram of the doped structure of a silicon-based electro-optic modulator according to another specific embodiment of the present invention;

Fig. 5 is a schematic diagram of the attenuation law of the signal when the microwave signal is transmitted on the high-frequency electrode of the modulator according to a specific embodiment of the present invention.

Reference signs: optical waveguide propagation direction-1; first doped region-2; second doped region-3, third doped region-4; fourth doped region-5; second doped region and second doped region Three-doped area contact surface-6.

detailed description

The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary, and are intended to explain the present invention, but should not be construed as limiting the present invention.

In the traditional uniform doping structure, when the microwave signal is transmitted on the electrode along the transmission direction, the signal amplitude will gradually attenuate, resulting in non-uniform modulation efficiency at different positions of the entire modulation arm. The high-concentration doping in the modulation arm brings additional transmission loss but cannot effectively improve the modulation efficiency, which is a problem with most current doped structures.

The embodiment of the present invention proposes a doping structure of a silicon-based integrated modulator. This structure optimizes the ion doping structure along the light wave transmission direction, so that the modulation efficiency of the modulation arm is more balanced, and the modulation efficiency is shorter. The length of the modulator realizes more efficient electro-optical modulation and lower optical signal transmission loss.

The doping structure of a silicon-based electro-optic modulator according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the doped structure of a silicon-based electro-optic modulator according to an embodiment of the present invention.

As shown in FIG. 1, the silicon-based electro-optic modulator doped structure includes: a first doped region 2, a second doped region 3, a third doped region 4 and a fourth doped region 5. Among them, 1 is the light propagation direction.

The first doped region 2 and the second doped region 3 have the same doping type, the second doped region 3 and the third doped region 4 have opposite doped types, and the third doped region 4 is doped with the fourth doped region 5 Miscellaneous types are the same;

The contact surfaces 6 of the second doped region 3 and the third doped region 4 alternately form a periodic structure, and the periodic structure is adjusted by the amplitude of the microwave signal.

Further, in an embodiment of the present invention, the doping type of the first doped region 2 and the second doped region 3 is P-type, the first doped region 2 is a P-type heavily doped region, and the second doped region The region 3 is a P-type lightly doped region, and the first doped region 2 is arranged above the second doped region 3;

The second doped region 3 is arranged above the third doped region 4;

The doping type of the third doped region 4 and the fourth doped region 5 is N-type, the third doped region 4 is an N-type lightly doped region, and the fourth doped region 5 is an N-type heavily doped region. The doped region 4 is arranged above the fourth doped region 5.

Further, in another embodiment of the present invention, the doping type of the first doped region 2 and the second doped region 3 is N-type, the first doped region 2 is an N-type heavily doped region, and the second doped region The doped region 3 is an N-type lightly doped region, and the first doped region 2 is disposed above the second doped region 3;

The second doped region 3 is arranged above the third doped region 4;

The doping type of the third doped region 4 and the fourth doped region 5 is P-type, the third doped region 4 is a P-type lightly doped region, the fourth doped region 5 is a P-type heavily doped region, and the third doped region 4 is a P-type lightly doped region. The doped region 4 is arranged above the fourth doped region 5.

The doping structure of the silicon-based integrated modulator will be described in detail with reference to FIGS. 2, 3 and 4.

Along the light propagation direction 1 in the optical waveguide, the contact surfaces of the second doped region 3 and the third doped region 4 are staggered to form a periodic structure that changes according to certain physical laws, such as in the high-frequency electrode of a silicon-based modulator The changing law of signal attenuation.

Specifically, by adjusting the periodic structure by the amplitude of the microwave signal, the amplitude of the microwave signal is inversely proportional to the contact area of the contact surface of the second doped region 3 and the third doped region 4.

FIG. 2, FIG. 3, and FIG. 4 respectively show the periodic structure of the contact surface 6 of the second doped region 3 and the third doped region 4 with different shapes. Wherein, the contact surface 6 shown in FIG. 2 is a periodic structure with a rectangular distribution, the contact surface 6 shown in FIG. 3 is a periodic structure with a zigzag distribution, and the contact surface 6 shown in FIG. 4 is a periodic structure with a trigonometric function change type.

As shown in FIG. 2, it is an embodiment of the present invention. The first doped region 2 of the uppermost layer is a P-type heavily doped region, followed by a P-type lightly doped region, an N-type lightly doped region, and N-type heavily doped region. The P-type lightly doped area and the N-type lightly doped area are staggered at the contact surface 6 to form a rectangular contact surface. The size of the rectangular contact surface changes, and the size of the rectangular contact surface is determined according to the attenuation amplitude of the microwave signal. It can be seen from the figure that the width of the rectangle gradually narrows from left to right.

As shown in FIG. 3, which is another embodiment of the present invention, the first doped region 2 of the uppermost layer is a P-type heavily doped region, and the P-type lightly doped region and the N-type lightly doped region are successively lowered. And N-type heavily doped regions. The P-type lightly doped area and the N-type lightly doped area are staggered at the contact surface 6 to form a zigzag contact surface. As in Figure 2, the size of the saw-tooth contact surface is variable, and the size of the saw-tooth contact surface is determined according to the attenuation amplitude of the microwave signal. It can be seen from the figure that the width of the zigzag shape gradually narrows from left to right.

As shown in FIG. 4, which is another embodiment of the present invention, the first doped region 2 of the uppermost layer is a P-type heavily doped region, and the P-type lightly doped region and the N-type lightly doped region are successively lowered. And N-type heavily doped regions. The P-type lightly doped region and the N-type lightly doped region are staggered at the contact surface 6 to form a contact surface of a trigonometric function change type. Same as Figures 2 and 3, the size of the contact surface is variable, and the size of the contact surface is determined according to the attenuation amplitude of the microwave signal. It can be seen from the figure that the distance between the peak and the valley is gradually narrowing.

It should be noted that the contact area in the embodiment of the present invention may specifically refer to the second doped region 3 and the third doped region within each preset width range along the light propagation direction 1 in the optical waveguide. 4 contact area between. Thus, as the width of the rectangle gradually narrows, or the width of the zigzag shape gradually narrows, or the distance between the peak and the valley gradually narrows, the number of rectangles or the number of sawtooth shapes or peaks within each preset width range The number of wave troughs gradually increases, so that the contact area between the second doped region 3 and the third doped region 4 gradually increases.

As shown in Figure 5, it shows the attenuation law of the signal when the microwave signal is transmitted on the high-frequency electrode of the modulator. The signal has just been transmitted to the electrode, the signal attenuation is small, the amplitude is large, the voltage actually loaded on the PN junction is large, and the modulation effect is large. As the signal is transmitted, the signal attenuates and the amplitude decreases. The voltage actually loaded on the PN junction is smaller than before. The corresponding modulation effect is small. Therefore, by reducing the contact area between the P-type doping and the N-type doping at the position where the microwave signal amplitude is large, the modulation efficiency is reduced while reducing the loss. At the position where the microwave signal amplitude is small, the P-type doping and N-type doping are increased. The N-type doped contact area increases the modulation efficiency and also increases the loss. The modulation efficiency of the entire modulation arm is uniform and the average loss is smaller.

Through the above introduction, the pattern of the contact surface of the doped region can have various forms, and is not limited to the above three specific embodiments. The doping pattern can be changed according to the design of different electrodes, which is compared with traditional uniform doping or periodic doping. Hybrid structure, the embodiment of the present invention matches the doping pattern with the working mode and electrode design of the modulator, and balances the modulation efficiency and loss.

According to the silicon-based electro-optical modulator doped structure proposed by the embodiment of the present invention, the contact area of the doped area is adjusted according to the attenuation of the microwave signal, the modulation efficiency is appropriately reduced at the place where the microwave signal is not attenuated, and the device loss, device length, and The relationship between the modulation efficiency of the three.

In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean specific features described in conjunction with the embodiment or example , Structure, materials or features are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above-mentioned terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples and the features of the different embodiments or examples described in this specification without contradicting each other. Although the embodiments of the present invention have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can comment on the above-mentioned embodiments within the scope of the present invention. The embodiment undergoes changes, modifications, substitutions, and modifications.

Claims (7)

1. A silicon-based electro-optic modulator doped structure, which is characterized in that it comprises:

   A first doped region, a second doped region, a third doped region, and a fourth doped region;

   The doping type of the first doped region is the same as that of the second doped region, the doping type of the second doped region is opposite to that of the third doped region, and the third doped region is the same as that of the third doped region. The fourth doped region has the same doping type;

   The contact surfaces of the second doped region and the third doped region are staggered to form a periodic structure, and the periodic structure is adjusted by the amplitude of the microwave signal.
2. The silicon-based electro-optic modulator doped structure according to claim 1, wherein:

   The doping type of the first doped region and the second doped region is P-type, the first doped region is a P-type heavily doped region, and the second doped region is a P-type lightly doped region Region, the first doped region is disposed above the second doped region;

   The second doped region is arranged above the third doped region;

   The third doped region and the fourth doped region have a doping type of N-type, the third doped region is an N-type lightly doped region, and the fourth doped region is an N-type heavily doped region. Region, the third doped region is arranged above the fourth doped region.
3. The silicon-based electro-optic modulator doped structure according to claim 1, wherein:

   The doping type of the first doped region and the second doped region is N-type, the first doped region is an N-type heavily doped region, and the second doped region is an N-type lightly doped region. Region, the first doped region is disposed above the second doped region;

   The second doped region is arranged above the third doped region;

   The doping type of the third doped region and the fourth doped region is P-type, the third doped region is P-type lightly doped region, and the fourth doped region is P-type heavily doped Region, the third doped region is arranged above the fourth doped region.
4. The silicon-based electro-optic modulator doped structure according to claim 1, wherein:

   The periodic structure is a rectangular distributed periodic structure.
5. The silicon-based electro-optic modulator doped structure according to claim 1, wherein:

   The periodic structure is a periodic structure distributed in a zigzag shape.
6. The silicon-based electro-optic modulator according to claim 1, wherein:

   The periodic structure is a periodic structure of a trigonometric function change type.
7. The silicon-based electro-optic modulator doped structure according to claim 1, wherein the amplitude of the microwave signal is inversely proportional to the contact area of the contact surface between the second doped region and the third doped region.

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