CN101465358A - Differential silicon photodetector made by CMOS technique - Google Patents
Differential silicon photodetector made by CMOS technique Download PDFInfo
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- CN101465358A CN101465358A CNA2007101798926A CN200710179892A CN101465358A CN 101465358 A CN101465358 A CN 101465358A CN A2007101798926 A CNA2007101798926 A CN A2007101798926A CN 200710179892 A CN200710179892 A CN 200710179892A CN 101465358 A CN101465358 A CN 101465358A
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Abstract
The invention provides a differential silicon photodetector made through the CMOS integrated circuit process; the differential silicon photodetector comprises a substrate (16), and first, second, third, fourth, fifth and sixth wells (10), and first, second, third, fourth, fifth and sixth diffusion regions (11), as well as a seventh diffusion region (15); the wells (10) are arranged on the substrate at equal intervals; the six diffusion regions are respectively arranged at the centers of the six wells; the seventh diffusion region is arranged outside the six diffusion regions and the six wells; the first, third and fifth diffusion regions are provided with contact holes (14) and are connected together through a first layer of metal (12); the second, fourth and sixth diffusion regions are covered with the first layer of metal and are light-tight; while the second, fourth and sixth diffusion regions are provided with contact holes and are connected together through a second layer of metal (13).
Description
Technical field
The present invention relates to silica-based monolithic photoelectron integrated technology, be specifically related to the differential silicon photodetector that adopts the standard CMOS integrated circuit technology to make.
Background technology
In the modern society of scientific and technical fast development, a large amount of information and exchanges data need the communication system in a high speed, broadband.Theoretical Calculation shows: can increase frequency bandwidth expansion capacity of communication system thereby increase carrier frequency.When the signal of telecommunication transmitted on conductor, the impedance of conductor and parasitic capacitance can increase along with the frequency increase made the signal of telecommunication decay rapidly.Even adopt the less coaxial cable of high-frequency loss, its loss has also reached 5dB/Km under the 100MHz frequency.Therefore cable only is suitable for short distance and low frequency use down, and can't satisfy high speed long haul communication needs.Mutually reflective have high frequency (hundreds of THz), so the transmission system of broadband high-speed can be provided.Usually the medium of transmitting optical signal all has one specific wavelength is transparent window, and the loss that light transmits in transparent window is minimum.These windows are positioned at visible light and near infrared region, and correspondent frequency is 150THz～800THz, are 10 of signal of telecommunication transmission frequencies
6Doubly! With the high frequency light wave be that the optical fiber communication of carrier has bandwidth, loss is low, volume is little, exempt from electromagnetic interference, advantage such as high reliability, make it become one of communication mode the most rising in the existing various means of communication, become the foundation stone that the mankind march toward information-intensive society.
Growing apart from ultrahigh speed backbone network communication aspects, though optical communication has obtained unprecedented success.But its optical transceiver module uses all is expensive III-V family material, for example GaAs and InP-InGaAs.Though these III-V family material opto-electronic devices cost an arm and a leg, its photoelectric characteristic is very good, can reach modulation and the detection rate of 40Gbit/s easily.For communication backbone, what people pursued is the wide-band communication system of performance brilliance, and because a plurality of user's share the expenses, price are arranged is not restraining factors usually.Yet in short haul connection, for example in the local area network (LAN) owing to there is not user's share the expenses, price has just become restraining factors.Expensive III-V family material opto-electronic device has limited its being extensive use of in local area network (LAN), and people can only hope " light " to heave a sigh.Along with the continuous progress of information technology,, need photoelectron receiver module cheaply simultaneously for application such as optical information storage, light transfer of data.Be necessary to develop cheap Optical Receivers thus to remedy the deficiency of these III-V family material opto-electronic devices, make optical communication enter into huge numbers of families, to extend arterial grid superfast " last kilometer ", realization optical fiber is registered one's residence.
Si base detector receiver has just remedied this shortcoming, utilize common si-substrate integrated circuit production technology, these technologies are being changed hardly or only doing on the basis of small adjustment, Si base detector and receiver monolithic are integrated becomes a complete Optical Receivers.Because making the opto-electronic device by the integrated circuit technology manufacturing have, the promoting the use of of the maturation, particularly CMOS technology of integrated circuit technology to produce cheap advantage in batches.Simultaneously in view of the easness of CMOS technology to deep-submicron development and maturity and the support of acquisition production line, the existing circuit that may realize Gb/s speed with advanced person's CMOS technology.It is that unlimited vigor has been injected in the development of Si base monolithic integrated receiver that CMOS has advantages such as integrated level height, volume are little, low-work voltage, low-power consumption, low cost, high reliability.The differential silicon photodetector that the present invention adopts the standard CMOS integrated circuit technology to make, can on standard CMOS integrated circuit technology line, flow finish, preparation when realizing photodetector and receiver circuit, thereby monolithic integrated detector and receiver circuit on a slice silicon substrate, can be widely used in optical communication in the local area network (LAN), have practical significance.
Summary of the invention
The purpose of this invention is to provide a kind of employing standard CMOS process and make SML (Spatially-Modulated-Light, spatial light modulation) differential silicon photodetector, its have manufacture craft maturation, cost low, be suitable for integrated, be easy to advantages such as large-scale production.This detector can realize that monolithic is integrated with the CMOS receiver circuit.1 * 12 array that is made of this detector can be applicable to VSR (transmission of VeryShort Reach very short distance) system, to realize 12 the tunnel and the transmission of traveling optical signal.
Basic structure of the present invention is six staggered detectors that formed by six n+ diffusion and six n wells and p substrate, the n+ diffusion is in order to reduce contact resistance, lightly doped n well is as absorbed layer, and light dope is in order to increase depletion width parasitic capacitance to be reduced.In six interdigital search coverages three are covered stopping incident light by metal level, and these three interdigital connects together as " second detector " with metal, and remaining three also connect together as " first detector " with metal.When incident illumination is mapped to detector surface, the surface of " second detector " makes not transmissive of light owing to being covered by metal level, incident light only is absorbed the generation photo-generated carrier in " first detector " zone, i.e. the distribution of charge carrier quilt " second detector " surface coverage metal " modulation ".Be located at the t0 moment very short pulsed light of a branch of duration and incide detector surface, at this moment " first detector " zone has produced many photo-generated carriers, and " second detector " zone and carrier-free distribute.These photo-generated carriers can be divided into two parts, and a part is that another part is outside depletion region in depletion region.Float to " first detector " electrode fast under the interior carrier depletion district electric field action that produces of depletion region, and the outer charge carrier part that produces of depletion region spreads to " first detector " zone, another part is then to the diffusion of " second detector " zone.Through after a bit of time, " second detector " zone also has the charge carrier that diffusion is come in, and the charge carrier in " first detector " zone is because diffusion and drift reduce the charge carrier number simultaneously.Along with the continuation of diffusion, the charge carrier in " first detector " zone reduces gradually, and " second detector " regional charge carrier increases gradually.The charge carrier in two zones or owing to compound disappear or owing to be diffused into the depletion region border under the depletion region electric field action outside drift electrode, thereby detected by two detectors respectively.
Concrete, the present invention proposes the differential silicon photodetector that a kind of CMOS of employing integrated circuit technology is made, and it comprises:
A substrate 16;
First, second, third and fourth, five, six traps 10, described trap is produced on the described substrate equally spacedly;
First, second, third and fourth, five, six diffusion regions 11, described six diffusion regions are produced in the centre of described six traps;
The 7th diffusion region 15, described the 7th diffusion region are produced on described six diffusion regions and described six traps outside;
Described first, make contact hole 14 on the 3rd and the 5th diffusion region, by ground floor metal 12 these three diffusion regions are connected together;
On described second, the 4th and the 6th diffusion region, cover the ground floor metal, make these diffusion regions light tight;
On described second, the 4th and the 6th diffusion region, make contact hole, these three diffusion regions are connected together by second layer metal 13.
Further, described substrate is a p type silicon substrate.
Further, described six traps are n type trap.
Further, described six diffusion regions are the n+ diffusion region.
Further, described the 7th diffusion region is the P+ diffusion region.
Further, described P+ diffusion region surrounds whole detector as the detector anode, to guarantee good substrate contact.
Further, with printing opacity first, the pn junction detector that forms of the 3rd and the 5th n+ diffusion region and p type substrate connects together and forms first detector; The pn junction detector that lighttight second, the 4th and the 6th n+ diffusion region and p type substrate are formed connects together and forms second detector.
Further, first detector and second detector are staggered, and effectively photo-signal is that the first detector current signal deducts the second detector current signal.
Further, the flow on CMOS integrated circuit technology line of described detector is finished, preparation when realizing photodetector and receiver circuit, thereby on a slice silicon substrate monolithic integrated detector and receiver circuit.
Can be obtained by above analysis, the charge carrier that " first detector " collected not only contains the drift composition but also contains diffusion component, and the charge carrier that " second detector " collected only contains diffusion component.If the photoelectric current that " first detector " produced deducts the photoelectric current that " second detector " produces, so just can eliminate the diffusion component adverse effect, eliminate because of " hangover " of the response current of diffusion component generation thereby phenomenon raising speed.The present invention just is being based on this phenomenon, and " first detector " current signal is deducted the effective photo-signal of " second detector " current signal as differential detector, thereby improves the detector frequency response, makes it satisfy the demand of high speed optical communication.
Description of drawings
Fig. 1 is a top view of the present invention;
Fig. 2 is a transverse cross-sectional view of the present invention;
Fig. 3 is a photoproduction carrier concentration schematic diagram of the present invention;
Fig. 4 is a photoelectric current transient response curve of the present invention.
Embodiment
Because the present invention uses standard CMOS process, therefore can transfer to chip foundries (Foundry) and produce by the form of domain, its domain top view is as shown in Figure 1.It is characterized in that, comprising:
A p type silicon substrate 16;
First, second, third and fourth, five, six n type traps 10 are equidistantly staggered is produced on the p type silicon substrate 16;
First, second, third and fourth, five, six n+ diffusion regions 11 are produced on the centre of six n type traps 10;
A P+ diffusion region 15, this P+ diffusion region 15 are produced on n+ diffusion region 11 and n type trap 10 outsides;
Make contact hole 14 at first, on the 3rd and the 5th the n+ diffusion region 11, these three n+ diffusion regions 11 are connected together by ground floor metal 12;
On second, the 4th and the 6th n+ diffusion region 11, cover ground floor metal 12, make these diffusion regions light tight;
On second, the 4th and the 6th n+ diffusion region 11, make contact hole 14, these three n+ diffusion regions 11 are connected together by second layer metal 13.
The PN junction of n type trap 10 and n+ diffusion region 11 and substrate 16 constitutes photodiode.With printing opacity first, the formation " first detector " that connects together of the pn junction detector that forms of the 3rd and the 5th n+ diffusion region and p type substrate; The pn junction detector that lighttight second, the 4th and the 6th n+ diffusion region and p type substrate the are formed formation " second detector " that connects together.The response speed of " first detector " is very fast, and " second detector " response speed is slower." first detector " and " second detector " is staggered, and effectively photo-signal deducts " second detector " current signal for " first detector " current signal.
Fig. 2 is a transverse cross-sectional view of the present invention, and the detector that is made of n type trap 20 and n+ diffusion region 21 and substrate 24 is staggered, and P+ diffusion region 22 surrounds whole detector, and second layer metal 23 covers " second detector " and makes it light tight.When incident illumination was mapped to detector surface, the surface of " second detector " made not transmissive of light owing to being covered by metal level, and incident light only is absorbed the generation photo-generated carrier in " first detector " zone.
Fig. 3 is a photoproduction carrier concentration schematic diagram of the present invention.Be located at the t=t0 moment very short pulsed light of a branch of duration and incide detector surface, at this moment " first detector " zone has produced many photo-generated carriers, and " second detector " zone and carrier-free distribute, i.e. the distribution of charge carrier quilt " second detector " surface coverage metal " modulation ".These photo-generated carriers can be divided into two parts, and a part is that another part is outside depletion region in depletion region.Float to " first detector " electrode fast under the interior carrier depletion district electric field action that produces of depletion region, and the outer charge carrier part that produces of depletion region spreads to " first detector " zone, another part is then to the diffusion of " second detector " zone.Through after a bit of time at t=t1 constantly, " second detector " zone also has the charge carrier that diffusion is come in, the charge carrier in " first detector " zone is because diffusion and drift reduce the charge carrier number simultaneously.Along with the continuation of diffusion, the charge carrier in " first detector " zone reduces gradually, and " second detector " regional charge carrier increases gradually.Charge carrier number in the t=t3 moment two zones is approaching identical, at this time charge carrier has no longer been modulated because the distribution of the charge carrier in two zones of " first detector " and " second detector " is identical, and definition △ t=t3-t0 is the charge carrier modulating time.This latter two regional charge carrier or owing to compound disappear or owing to be diffused into the depletion region border under the depletion region electric field action outside drift electrode, thereby detected by two detectors respectively.Therefore all less at the charge carrier number in the t=t4 moment two zones.
By the above analysis that charge carrier is distributed, we can find that the charge carrier that " first detector " collected not only contains the drift composition but also contains diffusion component, and the charge carrier that " second detector " collected only contains diffusion component.If the photoelectric current that we produce " first detector " deducts the photoelectric current that " second detector " produces, so just can eliminate the diffusion component adverse effect, eliminate the response current that produces because of diffusion component " hangover " thus phenomenon raising speed.The prerequisite of subtracting each other like this is because the pn district very thick (12 μ m) of detector, the modulating time of charge carrier is far smaller than charge carrier from producing extinction time, also promptly have only after the incident light irradiation in very short a period of time charge carrier to distribute to be only modulated, these charge carriers are even in " first detector " and " second detector " two regional concentration Gradient distribution already before charge carrier disappears.Be carved into charge carrier during from t3 and disappear this segment length in the time, the carrier moving process in two zones is similarly, all needs could to arrive external electrode by very long diffusion and produces photoelectric current.Therefore we subtract each other the effective probe current that obtains with two detector current and have eliminated the influence that very long charge carrier causes detector speed diffusion time constantly at t3.
Fig. 4 is photoelectric current transient response curve figure of the present invention, and incident light is the sine wave of 2GHz.Under the sinusoidal incident light of 2GHz, the photo-signal distortion of " first detector " and " second detector " two detectors is all very serious as seen from the figure, can't correctly respond incident field and change.The effective photo-signal after but they subtract each other but can respond incident light fast, and distortion is very little.Further verified the fast advantage of differential detector response speed.
The function that two detector photo-signals are subtracted each other in realization is finished by trans-impedance amplifier and differential amplifier.Because the present invention adopts CMOS standard integrated circuit technology to be made, therefore when making detector, realize follow-up trans-impedance amplifier and differential amplifier very easily, thereby extract effective photo-signal, satisfy the high speed optical communication needs.
This differential silicon photodetector is made with CMOS technology fully, need not change any operation and material in the CMOS technology, can on the process production line of production firm (Foundry), together make with the CMOS integrated circuit, realize microelectronic component and opto-electronic device simultaneously, really realized photoelectron and microelectronic integrated.The monolithic of silicon based opto-electronics detector and receiving circuit is integrated not only to have opto-electronic conversion and enlarging function, and because silicon integrated circuit is ripe, can introduce logical process, storage and the Based Intelligent Control function of electronics easily.And because optoelectronic IC has been eliminated the influence of parasitic parameters such as encapsulation, lead-in wire and line, can realize high speed, have also simultaneously that volume is little, rate of finished products is high and advantage such as good reliability.
So far invention has been described in conjunction with the preferred embodiments.Should be appreciated that those skilled in the art can carry out various other change, replacement and interpolations under the situation that does not break away from the spirit and scope of the present invention.Therefore, scope of the present invention is not limited to above-mentioned specific embodiment, and should be limited by claims.
Claims (9)
1. a differential silicon photodetector that adopts the CMOS integrated circuit technology to make is characterized in that, comprising:
A substrate (16);
First, second, third and fourth, five, six traps (10), described trap is produced on the described substrate equally spacedly;
First, second, third and fourth, five, six diffusion regions (11), described six diffusion regions are produced in the centre of described six traps;
The 7th diffusion region (15), described the 7th diffusion region are produced on described six diffusion regions and described six traps outside;
Described first, make contact hole (14) on the 3rd and the 5th diffusion region, by ground floor metal (12) these three diffusion regions are connected together;
On described second, the 4th and the 6th diffusion region, cover the ground floor metal, make these diffusion regions light tight;
On described second, the 4th and the 6th diffusion region, make contact hole, these three diffusion regions are connected together by second layer metal (13).
2. detector according to claim 1 is characterized in that, described substrate is a p type silicon substrate.
3. detector according to claim 1 and 2 is characterized in that, described six traps are n type trap.
4. detector according to claim 1 and 2 is characterized in that, described six diffusion regions are the n+ diffusion region.
5. detector according to claim 1 and 2 is characterized in that, described the 7th diffusion region is the P+ diffusion region.
6. detector according to claim 5 is characterized in that, described P+ diffusion region surrounds whole detector as the detector anode, to guarantee good substrate contact.
7. detector according to claim 4 is characterized in that, with printing opacity first, the pn junction detector that forms of the 3rd and the 5th n+ diffusion region and p type substrate connects together and forms first detector; The pn junction detector that lighttight second, the 4th and the 6th n+ diffusion region and p type substrate are formed connects together and forms second detector.
8. detector according to claim 7 is characterized in that, first detector and second detector are staggered, and effectively photo-signal is that the first detector current signal deducts the second detector current signal.
9. detector according to claim 1, it is characterized in that, the flow on CMOS integrated circuit technology line of described detector is finished, preparation when realizing photodetector and receiver circuit, thereby on a slice silicon substrate monolithic integrated detector and receiver circuit.
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| CN2007101798926A CN101465358B (en) | 2007-12-19 | 2007-12-19 | Differential silicon photodetector made by CMOS technique |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102593132A (en) * | 2012-02-24 | 2012-07-18 | 天津大学 | Lamination differential photoelectric detector based on standard CMOS (complementary metal oxide semiconductor) process |
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| JP3108528B2 (en) * | 1992-05-28 | 2000-11-13 | 株式会社東芝 | Optical position detection semiconductor device |
| CN1607671A (en) * | 2003-10-14 | 2005-04-20 | 中国科学院半导体研究所 | Method for making CMOS process compatible silicon photoelectric detector |
| CN100433340C (en) * | 2003-12-31 | 2008-11-12 | 天津大学 | Silicon photoelectric probe compatible with deep submicron radio frequency technology |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102593132A (en) * | 2012-02-24 | 2012-07-18 | 天津大学 | Lamination differential photoelectric detector based on standard CMOS (complementary metal oxide semiconductor) process |
| CN102593132B (en) * | 2012-02-24 | 2014-04-30 | 天津大学 | Lamination differential photoelectric detector based on standard CMOS (complementary metal oxide semiconductor) process |
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| CN101465358B (en) | 2010-06-09 |
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