阅读说明：本技术 基于双控制栅的复合介质栅可控自增益光敏探测器件 (Composite dielectric gate controllable self-gain photosensitive detection device based on double control gates ) 是由 马浩文 于 2019-10-12 设计创作，主要内容包括：本发明公开了一种基于双控制栅的复合介质栅可控自增益光敏探测器件。该器件包括复合介质栅、MOS电容和感光晶体管，复合介质栅的P型基底上方依次设有底层介质层、浮栅和顶层介质层，顶层介质层上方设有MOS电容的控制栅极和感光晶体管的控制栅极，感光晶体管的控制栅极通过互连导线和P型基底连接；MOS电容和感光晶体管设置在P型基底内，并通过浅槽隔离；感光晶体管设有源极和漏极；MOS电容和感光晶体管之间通过浮栅相连。本发明的器件能实现低功耗的感光自增益功能和增益控制功能，同时满足对强光和弱光的探测需求，实现高动态范围的光敏探测。(The invention discloses a composite dielectric gate controllable self-gain photosensitive detection device based on a dual-control gate. The device comprises a composite dielectric gate, an MOS capacitor and a photosensitive transistor, wherein a bottom dielectric layer, a floating gate and a top dielectric layer are sequentially arranged above a P-type substrate of the composite dielectric gate, a control grid of the MOS capacitor and a control grid of the photosensitive transistor are arranged above the top dielectric layer, and the control grid of the photosensitive transistor is connected with the P-type substrate through an interconnection lead; the MOS capacitor and the photosensitive transistor are arranged in the P-type substrate and are isolated by a shallow groove; the photosensitive transistor is provided with a source electrode and a drain electrode; the MOS capacitor is connected with the photosensitive transistor through a floating gate. The device can realize the photosensitive self-gain function and the gain control function with low power consumption, simultaneously meet the detection requirements on strong light and weak light, and realize the photosensitive detection with high dynamic range.)

1. The composite dielectric gate controllable self-gain photosensitive detection device based on the double control gates is characterized in that the photosensitive detection device comprises a composite dielectric gate, an MOS capacitor and a photosensitive transistor, a bottom dielectric layer, a floating gate and a top dielectric layer are sequentially arranged above a P-type substrate of the composite dielectric gate, a control gate of the MOS capacitor and a control gate of the photosensitive transistor are arranged above the top dielectric layer, and the control gate of the photosensitive transistor is connected with the P-type substrate through an interconnection lead; the MOS capacitor and the photosensitive transistor are arranged in the P-type substrate and are isolated by a shallow groove; the photosensitive transistor is provided with a source electrode and a drain electrode; the MOS capacitor is connected with the photosensitive transistor through a floating gate.

2. The dual control gate based composite dielectric gate controllable self-gain photosensitive probing device according to claim 1 wherein said floating gate is an electronic conductor or semiconductor.

3. The dual control gate based composite dielectric gate controllable self-gain photosensitive probe device of claim 1, wherein the MOS capacitor and the photosensitive transistor share a floating gate.

4. The dual-control-gate-based composite dielectric gate controllable self-gain photosensitive detection device according to claim 1, wherein the control gate of the MOS capacitor and the control gate of the photosensitive transistor are polysilicon, metal or transparent conductive electrodes.

5. The dual-control-gate-based composite dielectric gate controllable self-gain photosensitive detection device according to claim 1, wherein at least one of the control gate of the photosensitive transistor or the P-type substrate is a window transparent or semi-transparent to the detection wavelength of the detector.

6. The dual-control-gate-based composite dielectric gate controllable self-gain photosensitive detection device according to claim 1, wherein the bottom dielectric layer and the top dielectric layer are both made of insulating materials.

7. The dual control gate based composite dielectric gate controllable self-gain photosensitive detection device of claim 1, wherein the thicknesses of the bottom dielectric layer and the top dielectric layer above the MOS capacitor and the photosensitive transistor are the same or different.

8. The dual-control-gate-based composite dielectric gate controllable self-gain photosensitive detection device according to claim 1, wherein the thickness of the bottom dielectric layer and the top dielectric layer is greater than 6 nm.

9. The dual-control-gate-based composite dielectric gate controllable self-gain photosensitive detection device as claimed in claim 1, wherein the control gate and the P-type substrate of the photosensitive transistor are kept floating, the source of the photosensitive transistor is grounded, and a fixed voltage of 0.1V-3V is applied to the drain of the photosensitive transistor; and the control grid of the MOS capacitor is grounded or applied with grid voltage.

10. The dual-control-gate-based composite dielectric gate controllable self-gain photosensitive detection device according to claim 9, wherein the range of the control gate voltage applied to the control gate of the MOS capacitor is as follows: -3V to 3V.

Technical Field

The invention relates to a photosensitive detection device, in particular to a structure and a working mechanism of a controllable self-gain photosensitive detection device, and particularly relates to a controllable self-gain photosensitive detection device of a composite dielectric gate based on a double control gate.

Background

The semiconductor photosensitive device plays an extremely important role in the fields of daily life and national defense, such as an image sensor, a photosensitive switch, an optical power meter and the like. At present, most semiconductor photosensitive devices are applied under illumination, photons are absorbed by a semiconductor to generate electron-hole pairs, and current is generated through separation and movement of the electron-hole pairs. Of course, most of them require an applied voltage, and generally, the gain of the photoelectric conversion is a fixed value, which is difficult to apply under the conditions of photosensitive detection with high dynamic range and low power consumption.

The photosensitive device disclosed in the patent publication No. CN102938409A can convert an optical signal into a current signal, but it is premised that a certain voltage must be applied to the gate terminal or the substrate terminal, and it cannot perform photoelectric conversion without an applied voltage, and cannot realize a photosensitive self-gain function with low power consumption.

Although the photosensitive controllable device disclosed in the patent publication No. CN103137775A can realize a photosensitive self-gain function with low power consumption and can adjust the gain of photoelectric conversion to a certain extent, it realizes two operation states of inhibition and amplification by programming or erasing of FN tunneling, which is difficult to control accurately except for damage to the device, and thus cannot realize a gain control function in a true sense and cannot realize photosensitive detection in a high dynamic range.

Therefore, the existing photosensitive detection device cannot simultaneously meet the gain control function and the low-power-consumption photosensitive self-gain function, the actual demand puts forward the requirements on the high-integration and multifunctional photosensitive detection device, and the low-power-consumption photosensitive self-gain and gain-controllable photosensitive detection device can play a role in various fields.

Disclosure of Invention

The invention aims to provide a double-control-gate composite dielectric gate controllable self-gain photosensitive detector based on a composite dielectric gate MOSFET photosensitive detector.

The technical scheme adopted by the invention is as follows:

the composite dielectric gate controllable self-gain photosensitive detector based on the double control gates comprises a composite dielectric gate, an MOS capacitor and a photosensitive transistor, wherein a bottom dielectric layer, a floating gate and a top dielectric layer are sequentially arranged above a P-type substrate of the composite dielectric gate, a control gate of the MOS capacitor and a control gate of the photosensitive transistor are arranged above the top dielectric layer, and the control gate of the photosensitive transistor is connected with the P-type substrate through an interconnection wire; the MOS capacitor and the photosensitive transistor are arranged in the P-type substrate and are isolated by a shallow groove; the photosensitive transistor is provided with a source electrode and a drain electrode; the MOS capacitor is connected with the photosensitive transistor through a floating gate.

Further, the floating gate is an electron conductor or semiconductor.

Further, the MOS capacitor and the photosensitive transistor share a floating gate.

Further, the control grid of the MOS capacitor and the control grid of the photosensitive transistor are polysilicon, metal or transparent conductive electrodes.

Furthermore, at least one position of the control grid electrode or the P-type substrate of the photosensitive transistor is a window which is transparent or semitransparent to the detection wavelength of the detector.

Further, the bottom dielectric layer and the top dielectric layer are both made of insulating materials.

Furthermore, the thicknesses of the bottom dielectric layer and the top dielectric layer above the MOS capacitor and the photosensitive transistor are the same or different.

Further, the thickness of the bottom dielectric layer and the thickness of the top dielectric layer are both larger than 6 nm.

Furthermore, the control grid electrode and the P-type substrate of the photosensitive transistor keep floating, the source electrode of the photosensitive transistor is grounded, and the drain electrode of the photosensitive transistor is added with a fixed voltage of 0.1-3V; and the control grid of the MOS capacitor is grounded under the initial condition, and a fixed voltage of-3V-0V is applied to the control grid of the MOS capacitor under the strong illumination condition.

The photosensitive detector respectively realizes the gain control and the photosensitive self-gain function by using the gain control MOS capacitor and the self-gain photosensitive transistor, can realize the photosensitive self-gain function and the gain control function with low power consumption by combining different functions of the double control gates, simultaneously meets the detection requirements on strong light and weak light, and realizes the photosensitive detection with high dynamic range. The concrete characteristics and advantages are as follows:

(1) low power consumption self-gain: when the detection device of the invention carries out photoresponse, the response and the detection to light can be realized by adding a smaller bias voltage to the drain without adding a grid voltage or a substrate voltage. And because the substrate is interconnected with the control grid of the photosensitive transistor, a larger drain current can be caused by smaller illumination, and the function of low power consumption self-gain is effectively realized.

(2) High dynamic range: the detection device structure of the invention can select to apply proper modulation voltage on the control gate of the MOS capacitor according to the illumination intensity by the design of the double control gates, thereby realizing the regulation and control of the photoresponse gain on the device level. The method can ensure that the photoresponse can not reach saturation under strong light, can ensure that the drain current generated by the photoresponse under weak light is in a detectable range, and realizes the optical detection in a high dynamic range.

Drawings

FIG. 1 is a schematic structural diagram of a photosensitive detector device perpendicular to the channel direction of a composite dielectric gate transistor, namely the gate width direction;

FIG. 2 is a schematic diagram of the self-gain phototransistor parallel to the channel direction, i.e., the gate length direction;

FIG. 3 is a schematic structural diagram of a gain control MOS capacitor of the present invention parallel to the channel direction, i.e., the gate length direction;

FIG. 4 is a schematic view of voltage operation of the photo-sensitive detection device of the present invention at the time of photo-sensitive detection;

FIG. 5 is a graph of the photosensitive self-gain of the photosensitive detector device of the present invention;

FIG. 6 is a graph of the reduced gain of the photosensitive detector device of the present invention under bright light;

fig. 7 is a graph of gain increase for a photosensitive detection device of the present invention under low light.

Detailed Description

In order to make the disclosure of the present invention clearer, the following will further describe the embodiments of the present invention with reference to the accompanying drawings.

The dual-control-gate composite dielectric gate controllable self-gain photosensitive detector structure comprises a composite dielectric gate, a gain control MOS capacitor and a self-gain photosensitive transistor, wherein the gain control MOS capacitor realizes the gain control function of the detector, and the self-gain photosensitive transistor realizes the photosensitive self-gain function of the detector. Fig. 1-3 show schematic structures of a gain control MOS capacitor and a self-gain phototransistor in the gate width and gate length directions of the self-gain phototransistor, respectively, and the structures thereof include:

a semiconductor substrate (P-type); a bottom layer insulating medium, a floating gate, a top layer insulating medium, a control gate 1 and a control gate 2 are sequentially arranged right above a semiconductor substrate, the control gate 1 is a control gate of a capacitor, the control gate 2 is a control gate of a transistor, and the control gate 2 is connected with a P-type substrate through an interconnection lead; forming an N-type source electrode and a drain electrode in the semiconductor substrate (on one side of the self-gain photosensitive transistor) through ion implantation doping, and reading the magnitude of photocurrent; the gain control MOS capacitor and the self-gain photosensitive transistor are isolated by shallow slot; the floating gate is made of polysilicon and Si₃N₄Or other electronic conductors or semiconductors; the gain control MOS capacitor and the self-gain photosensitive transistor share the floating gate, so that the potential of the floating gate can be changed by the gain control MOS capacitor through the control gate 1, the threshold voltage of the self-gain photosensitive transistor is further changed, and the gain is controlled; the control gate 1 and the control gate 2 are made of polysilicon, metal or transparent conductive electrodes, and at least one of the control gate 2 or the P-type substrate base layer is a window transparent or semitransparent to the detection wavelength of the detector.

The bottom layer insulating medium layer and the top layer insulating medium can effectively isolate the floating gate and prevent electrons from tunneling into the floating gate; the insulating medium is generally a broadband semiconductor, wherein the bottom layer dielectric material adopts silicon oxide, SiON or other high dielectric constant media; the material of the top dielectric layer adopts silicon oxide/silicon nitride/silicon oxide, silicon oxide/aluminum oxide/silicon oxide, aluminum oxide or other high dielectric constant dielectric materials.

The interconnect lines are typically metal, polysilicon, or other low resistance conductive material.

Different from the traditional method for starting the transistor by externally adding a gate voltage exceeding a threshold value, the double-control-gate composite dielectric gate controllable self-gain photosensitive detection device of the invention separates electron-hole pairs generated by incident photons by utilizing a heterojunction barrier formed by interconnection of the control gate 2 and the P-type substrate of the transistor, the accumulation of the holes can promote the potentials of the P-type substrate and the control gate 2, namely an externally added gate voltage is added on the substrate and the control gate 2, and when the externally added gate voltage exceeds the threshold value, the transistor can be started, and detectable current can be generated at a drain electrode. Because no external grid voltage is needed, the transistor can be turned on only under illumination to generate current, and the transistor realizes the photosensitive self-gain function with low power consumption. And the control grid 1 regulates and controls the potential of the floating grid, so that the gain of photoelectric conversion can be controlled, and the detection requirements under different intensities of light intensity are met. Therefore, the composite dielectric gate controllable self-gain photosensitive detection device of the dual control gates of the embodiment can realize photosensitive self-gain and controllable variable gain.

The thicknesses of the bottom dielectric layer and the top dielectric layer above the gain control MOS capacitor and the self-gain photosensitive transistor can be the same or different. The thickness of the dielectric layer above the self-gain photo-sensing transistor may be lower than the thickness of the dielectric layer above the gain control MOS capacitor. The premise is that: and electrons at the interface of the self-gain photosensitive transistor and the bottom dielectric layer and at the source and drain ends of the self-gain photosensitive transistor are prevented from entering the floating gate in a tunneling mode. Generally, the thickness of the dielectric layer above the gain control MOS capacitor and the self-gain photosensitive transistor is larger than 6 nm.

Fig. 4 is a voltage operation diagram of the dual-control gate composite dielectric gate controllable self-gain photosensitive detector device in the embodiment during photosensitive detection, the interconnected control gate 2 and the P-type substrate are kept floating, the source of the self-gain photosensitive transistor is grounded, a fixed voltage of 0.1V to 3V is applied to the drain, and the control gate 1 is initially grounded; under the condition of illumination, incident photons generate electron hole pairs in the P-type base, and as the control gate 2 and the P-type base are interconnected and form a heterojunction structure, holes flow to the bottom of the substrate under the action of a heterojunction barrier, and electrons are accumulated on the surface of the substrate; the holes flowing to the bottom of the substrate raise the substrate potential, and the potential of the control gate 2 is correspondingly raised due to the existence of the interconnection wires; under the action of two phases, the self-gain photosensitive transistor is started up to reach a threshold value, obvious current can be detected at the drain electrode, the gain of light signals under the condition of no external grid voltage is realized, and the stronger the light intensity is, the larger the drain current is.

Under the illumination condition that the control gate 1 is initially grounded, the drain generates a corresponding current signal, and the stronger the light intensity is, the larger the drain current signal is, the weaker the light intensity is, the smaller the drain current signal is, and the gain of the photoelectric conversion is fixed; and through adding extra grid voltage on the control grid 1, the gain control MOS capacitor can change the potential of the floating grid according to the voltage on the control grid 1, so that the threshold voltage of the self-gain photosensitive transistor is changed, the magnitude of a drain current signal is adjusted, and the gain of photoelectric conversion is controlled. Under the condition of strong illumination, a fixed voltage of-3V-0V is applied to the control gate 1, so that a drain current signal can be reduced, the gain of photoelectric conversion is reduced, and a stronger optical signal can be detected; under the weak illumination condition, the control grid 1 is added with a fixed voltage of 0V-3V, so that the drain current signal can be increased, the gain of photoelectric conversion is improved, and a weaker optical signal can be detected.

Under the condition that the drain electrode is fixed to 0.5V and the control gate 1 is fixed to 0V, the self-gain curve of the dual-control gate composite dielectric gate controllable self-gain photosensitive detector device of the embodiment to the light intensity is shown in fig. 5. It can be seen that the detector device has a function of sensing self-gain, and its gain factor is a fixed value with the control gate 1 fixed at 0V.

Under the conditions that the drain electrode is fixed to be 0.5V, the control gate 1 is initially 0V, and the control gate 1 becomes-0.3V when the light intensity is strong, the controllable self-gain curve of the dual-control gate composite dielectric gate controllable self-gain photosensitive detector device of the embodiment to the light intensity is shown in FIG. 6. The detection device has the capability of reducing photoelectric conversion gain under strong light, and can meet the detection requirement on stronger light.

Under the condition that the drain electrode is fixed to be 0.5V, the control gate 1 is initially 0V, and the control gate 1 becomes 0.3V when the light intensity is weak, the controllable self-gain curve of the dual-control gate composite dielectric gate controllable self-gain photosensitive detector device of the embodiment to the light intensity is shown in FIG. 7. The detection device has the capability of increasing the photoelectric conversion gain under weak light, and can meet the detection requirement on weaker illumination.

With reference to fig. 5, fig. 6 and fig. 7, it can be seen that the dual-control gate composite dielectric gate controllable self-gain photosensitive detection device of the present embodiment can perform photosensitive detection of low power consumption photosensitive self-gain, and can select different values of photoelectric conversion gain according to different illumination intensities, and simultaneously meet the detection requirements for strong light and weak light, and implement optical detection in a high dynamic range.