CN104103658A - Bar grating type SOI photoelectric detector with resonant cavity enhancement effects - Google Patents

Abstract

The invention discloses a bar grating type SOI photoelectric detector with resonant cavity enhancement effects. The bar grating type SOI photoelectric detector with the resonant cavity enhancement effects solves the problem that semiconductor CMOS technology of an existing CMOS photoelectric detector structure limits improvements of device structures and electrical properties. The bar grating type SOI photoelectric detector with the resonant cavity enhancement effects comprises a P-type semiconductor substrate, a buried oxidation layer, an N-well region, a P-type ohm contact region, an annular ground electrode, an annular voltage electrode, an N-type ohm contact region, an output electrode, a bar grating type PCOMP, a top oxidation layer and polycrystalline silicon. The bar grating type SOI photoelectric detector with the resonant cavity enhancement effects is of bar grating structure, and increases the area of an exhaustion region. Simultaneously, due to the fact that an absorbing layer is thin, transition time of electron-hole pairs generated by photon-generated carriers is little when the electron-hole pairs are transited in the absorbing layer, the bar grating type SOI photoelectric detector with the resonant cavity enhancement effects is enabled to obtain high bandwidth, and the problem that quantum efficiency and the bandwidth of an existing photoelectric detector restrict each other is solved. The bar grating type SOI photoelectric detector with the resonant cavity enhancement effects has high responsiveness and the high bandwidth in work by changing transverse and lengthways structure (three dimensional structure) of the existing photoelectric detector.

Description

A bar-grid SOI photodetector with resonator-enhanced effect

technical field

The invention belongs to the technical field of semiconductors, and relates to a bar grid type SOI photodetector with resonant cavity enhancement effect.

Background technique

The growing demand for optical fiber communication, infrared remote sensing and military applications has promoted the development of semiconductor devices and their optical circuits. With the continuous manifestation of the powerful advantages of optical circuit systems, optoelectronic devices and their circuits have a wide range of applications in computing systems, free space satellite systems, optical disk storage applications, imaging systems, and communication systems. Considering the compatibility of the CMOS process, the traditional Si-based photodetector is implanted with n-type ions on the Si substrate to form an n-well region (n-well), and a p-well region is formed between the adjacent n-well regions on the top of the substrate. In the source region, the metal lead of the electrode is drawn out at the top of the source region; p-type ion implantation is carried out in the n-well region according to the grid type to form a grid-type PCOMP, and an n ohmic contact region is generated at the edge of the PCOMP and the n-well region, And the metal leads of the electrodes are drawn out on the top of the ohmic contact area; the ohmic contact area of p is formed on the top of each PCOMP, and the metal leads of the electrodes are drawn out on the top of the ohmic contact area. Due to the low absorption coefficient of Si in traditional CMOS photodetectors, the quantum efficiency is low. If the quantum efficiency is increased by increasing the thickness of the absorption layer, the bandwidth will be greatly reduced, which is not conducive to improving the comprehensive characteristics of the device and system. With the development of semiconductor technology and TCAD, CMOS photodetectors with structures such as spatial modulation (SML) and lateral PIN are limited by the CMOS process, and their responsivity and bandwidth cannot further meet the needs of ultra-high-speed short-distance optical interconnections. In order to realize a photodetector with higher responsivity and bandwidth, the researchers also proposed an avalanche breakdown photodetector (APD) structure based on the silicon CMOS process. The reason is that the photodetector needs to apply a high reverse bias voltage, which greatly limits the application range of the photodetector.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a new structure of SOI photodetector with resonant cavity enhancement effect bar grid type, by introducing a Fabry-Robb cavity and utilizing the bar grid structure to increase the area of the depletion region , so that the quantum efficiency is greatly increased without reducing the bandwidth. The device can be realized on the SOI CMOS process, has good process compatibility, and can be integrated with ordinary CMOS devices to form an optoelectronic integrated circuit chip or on-chip optoelectronic system; at the same time, compared with other compatible CMOS photodetectors, it has the characteristics of high quantum efficiency, high responsivity and high bandwidth.

The present invention is a resonant cavity enhanced photodetector with bar gate type PCOMP, comprising a p-type semiconductor substrate, a buried oxide layer, an n-type n-well well region, a p-type ohmic contact region, an annular ground electrode, and an annular voltage electrode , n-type ohmic contact area, output electrode, bar gate type PCOMP, top oxide layer and polysilicon;

A buried oxide layer is arranged at a distance of 2 um from the surface of the p-type semiconductor substrate, an n-type n-well well region is arranged on the upper surface of the p-type semiconductor substrate, and an annular p-type ohmic contact region is arranged on the upper surface of the p-type semiconductor substrate and is located at Outside the n-type n-well well region, the ring-shaped ground electrode is arranged on the ring-shaped p-type ohmic contact region, and the ring-shaped n-type ohmic contact region is arranged on the upper surface of the p-type semiconductor substrate and is located inside the n-type n-well well region. The voltage electrode is arranged on the ring-shaped n-type ohmic contact area, and a plurality of bar-type PCOMPs parallel to each other are arranged on the upper surface of the p-type semiconductor substrate and inside the ring-shaped voltage electrode; each bar-type PCOMP is provided with an output electrode ; A layer of oxide layer is covered between the electrodes on the upper surface of the p-type semiconductor substrate, and a layer of polysilicon is covered on the surface of the oxide layer.

The p-type semiconductor substrate is a sapphire substrate or a silicon substrate.

The thickness of the buried oxide layer is 140nm.

The thickness of the n-type n-well well region is 1.5um.

The thickness of the grid type PCOMP is 1um.

The oxide layer thickness of the top layer is 140nm.

The polysilicon thickness is 60nm.

The materials of the ring-shaped ground electrode, the ring-shaped voltage electrode and the output electrode are respectively Al or Cu.

The distance between the grid-type PCOMPs is 1um.

The epitaxial growth method of the buried oxide layer, n-type n-well well region, bar gate type PCOMP, annular p-type ohmic contact region and n-type ohmic contact region is realized by the method of oxygen injection isolation (SIMOX).

The new structure of the resonator-enhanced bar-grid SOI photodetector of the present invention introduces a Fabry-Robb cavity to make the light wave reciprocate in the cavity, so that the light wave passes through the absorbing layer multiple times to achieve the photoelectric enhancement effect, and the device can obtain Higher quantum efficiency. The strip gate structure is used to increase the area of the depletion region. At the same time, due to the thinner absorption layer, the electron-hole pairs generated by photogenerated carriers have a shorter transit time in the absorption layer, so that the device can obtain a higher bandwidth. , which solves the problem of mutual constraints between the quantum efficiency and bandwidth of photodetectors.

Beneficial effect: the invention makes the novel device have higher responsivity and bandwidth when working as a photodetector by changing the horizontal and vertical (three-dimensional) structures of the photodetector.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the top view of Fig. 1;

Fig. 3 is the A-A sectional schematic diagram of Fig. 1;

FIG. 4 is a schematic cross-sectional view of B-B in FIG. 1 .

Detailed ways

As shown in Figures 1, 2, 3 and 4, a resonator-enhanced photodetector with bar-gate PCOMP includes a p-type semiconductor substrate 1, a buried oxide layer 2, an n-type n-well well region 3, P-type ohmic contact area 4, annular ground electrode 5, annular voltage electrode 6, n-type ohmic contact area 7, output electrode 8, bar-type PCOMP 9, top oxide layer 11 and polysilicon 10;

A buried oxide layer 2 with a thickness of 140nm is provided at a distance of 2 um from the surface of the p-type semiconductor substrate 1, and an n-type n-well well region 3 with a thickness of 1.5 um is provided on the upper surface of the p-type semiconductor substrate 1, and an annular p-type ohmic The contact region 4 is arranged on the upper surface of the p-type semiconductor substrate 1 and is located outside the n-type n-well well region 3, the ring-shaped ground electrode 5 is arranged on the ring-shaped p-type ohmic contact region, and the ring-shaped n-type ohmic contact region 7 is arranged on the p-type ohmic contact region. The upper surface of the semiconductor substrate 1 is located inside the n-type n-well well region 3, the annular voltage electrode 6 is arranged on the annular n-type ohmic contact region 7, and the upper surface of the p-type semiconductor substrate 1 is arranged inside the annular voltage electrode 6 There are multiple grid-type PCOMP 9 parallel to each other with a thickness of 1um; the distance between the grid-type PCOMPs is 1um. Output electrodes 8 are set on each bar-gate PCOMP; a layer of oxide layer 11 with a thickness of 140 nm is covered between the electrodes on the upper surface of the p-type semiconductor substrate 1, and a layer of polysilicon 10 with a thickness of 60 nm is covered on the surface of the oxide layer. .

The p-type semiconductor substrate is a silicon substrate.

The three electrode materials described are Cu.

The epitaxial growth method of the buried oxide layer, n-type n-well well region, bar gate type PCOMP, annular p-type ohmic contact region and n-type ohmic contact region is realized by the method of oxygen injection isolation (SIMOX).

When photons are incident on the surface of the photosensitive device, the absorbed photons will excite the photosensitive material to generate electron-hole pairs, forming a current, which is called the photoelectric effect. The ratio of the number of electrons generated at this time to all the incident photons is called quantum efficiency. Quantum Efficiency Calculation Formula of Ordinary Photodetector , the formula for calculating the quantum efficiency of a resonant cavity photodetector , where r ₁ and r ₂ are the reflection coefficients of the upper and lower mirrors of the cavity, is the absorption coefficient of the material, and L is the thickness of the depletion layer. In the resonant cavity, due to the selection of the appropriate upper and lower mirrors, the reflection coefficient becomes larger, and the bar-grid structure can increase the effective area of the depletion layer, but it will not cause delay to the movement of carriers, so that it can be used in thin A larger quantum efficiency can be obtained when the depletion layer is used, while ensuring that the bandwidth will not be narrowed. When the top mirror is a pair of Si-SiO2 and the bottom mirror is three pairs of Si-SiO2, it can be calculated by the formula =0.325, which is 2-3 times that of ordinary photodetectors. This theoretically supports the method of improving the quantum efficiency of the device by using the bar grid resonant cavity structure, so that the device has a higher responsivity when used for optical interconnection.

Claims (10)

1. a SOI photodetector with resonant cavity enhancement effect bar grid type, comprises p-type Semiconductor substrate, buries oxide layer, N-shaped n-well well region, p-type ohmic contact regions, PCOMP, top layer oxide layer and the polysilicon of electrode, annular voltage pole, N-shaped ohmic contact regions, output electrode, bar grid type circlewise;

It is characterized in that: apart from p-type semiconductor substrate surface 2 um places, be provided with and bury oxide layer, p-type Semiconductor substrate upper surface is provided with N-shaped n-well well region, annular p-type ohmic contact regions is arranged on p-type Semiconductor substrate upper surface and is positioned at N-shaped n-well well region outside, electrode is arranged on annular p-type ohmic contact regions circlewise, the N-shaped ohmic contact regions of annular is arranged on p-type Semiconductor substrate upper surface and is positioned at N-shaped n-well well region inner side, annular voltage pole is arranged on annular N-shaped ohmic contact regions, at p-type Semiconductor substrate upper surface and be positioned at the PCOMP that annular voltage pole inner side is provided with many bar grid types parallel to each other, on the PCOMP of every bar grid type, output electrode is set, between each electrode of p-type Semiconductor substrate 1 upper surface, cover layer of oxide layer, at surface coverage one deck polysilicon of oxide layer.

2. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: described p-type Semiconductor substrate is Sapphire Substrate or silicon substrate.

3. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: the described oxidated layer thickness that buries is 140nm.

4. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: described N-shaped n-well well region thickness is 1.5um.

5. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: the PCOMP thickness of described bar grid type is 1um.

6. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: the oxidated layer thickness 140nm of described top layer.

7. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: described polysilicon thickness is 60nm.

8. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: the material of described electrode circlewise, annular voltage pole and output electrode is respectively a kind of of Al or Cu.

9. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: the distance between the PCOMP of bar grid type is 1um.

10. a kind of SOI photodetector with resonant cavity enhancement effect bar grid type according to claim 1, is characterized in that: the described epitaxial growth mode of burying oxide layer, N-shaped n-well well region, the PCOMP of bar grid type, HenXing ohmic contact regions, annular p-type ohmic contact regions adopts note oxygen partition method to realize.