High-performance IR detectors at SCD prent and future
O.NESHER*and P.C.KLIPSTEIN
Semi Conductor Devices(SCD),P.O.Box2250,Haifa31021,Israel
For over27years,SCD has been manufacturing and developing a wide range of high performance infrared detectors,de-signed to operate in either the mid-wave(MWIR)or the long-wave(LWIR)atmospheric windows.The detectors have been integrated successfully into many different types of system including missile ekers,time delay integration scanning sys-tems,hand-held cameras,missile warning systems and many others.SCD's technology for the MWIR wavelength range is bad on its well established2D arrays of InSb photodiodes.The arrays are flip-chip bonded to SCD's analogue or digital signal processors,all of which have been designed in-hou.The2D focal plane array(FP A)detectors have a format of 320×256elements for a30-µm pitch and480×384or640×512elements for a20-µm pitch.Typical operating temperatures are around77–85K.Five years ago SCD began to develop a new generation of MWIR detectors bad on the epitaxial growth of antimonide bad compound miconductors(ABCS).This ABCS technology allows band-gap engineering of the detection material which enables higher operating temperatures and multi-spect
初中英语知识点总结ral detection.This year SCD prented its first prototype FP A from this program,an InAlSb bad detector operating at a temperature of100K.By the end of this year SCD will introduce the first prototype MWIR detector with a640×512element format and a pitch of15µm.For the LWIR wavelength range SCD manufactures both linear Hg1–x Cd x Te(MCT)detectors with a line of250elements and time delay and integration(TDI)detectors with formats of288×4and480×6.Recently,SCD has demonstrated its first prototype uncooled detector which is bad on VO x technology and which has a format of384×288elements,a pitch of25µm,and a typical NETD of50mK at F/1.In this paper,we describe the prent technologies and products of SCD and the future evolu-tion of our detectors for the MWIR and LWIR detection.
Keywords:digital detector,480×384element detector,640×512element detector,focal plane array,MCT,IR detector, InSb,InAlSb,superlattice,TDI,DDC.
1.Introduction
Second generation infrared(IR)detectors at SCD are bad
on InSb for the mid-wavelength IR(MWIR)atmospheric
window(3–5ìm),and on mercury cadmium telluride
voyeur(MCT)for the long-wavelength IR(LWIR)window(8–12ìm)[1].In the past27years,SCD has developed and man-ufactured ten types of infrared detector,both with support
from the Israeli MOD and in cooperation with Israeli insti-
tutions and companies such as the Technion,Soreq NRC,
RICOR and RAFAEL.SCD's current production line in-
cludes MCT devices with up to4806elements operating in
time delay and integration(TDI)mode and two dimen-
sional(2D)InSb focal plane arrays(FPAs)with up to
640´512elements,all available in various configurations
including fully integrated detector-dewar-cooler(DDC)
packages.Many DDC configurations were developed,in
leonhard eulermost of the cas to custom design;they range from very
small low power and weight DDCs such as“Piccolo”[2]up to a very long TDI DDC for airborne applications with push-broom imaging,with2048×16elements[3].
SCD's2D InSb FPAs have been in production since 1997with the320´256element format and since2000in the larger format of640´512elements.SCD also special-izes in solutions optimized for various types of application from hand held cameras up to missile warning systems (MWS).The various solutions are bad on the special de-sign of Dewars which can endure a large range of environ-mental conditions and on the many operational modes of the signal processor which supports all the applications.
The general requirements of the third generation of IR detectors are:
•high resolution(larger format and smaller pitch),•advanced integrated readouts(digital,low noi),•higher operating temperatures(>77K),
•high spatial uniformity,
•high temporal stability,
•multi-spectral detection.
In order to be able to meet the third generation require-ments,SCD has started two main programs about five years ago which are both bad on the mature technology of pla-nar InSb2D arrays.The first one is focud on the signal processor which is bonded directly to the detection material,
OPTO-ELECTRONICS REVIEW14(1),61–70
*e-mail:il
The paper prented there appears in Infrared Photoelectronics, edited by Antoni Rogalski,Eustace L.Dereniak,Fiodor F.Sizov, Proc.SPIE Vol.5957,59570S(2005).
in this program we developed a family of digital readout in-tegrated circuits(ROIC)with a20-µm pitch which is called Sebastian[4,5].The first product of this program has a for-mat of640×512and it was first introduced in2003.Since then many detectors were produced and have been inte-grated successfully into systems.The cond product con-sists of480×384elements and since2004it has been manu-factured in SCD's production line[6].
The cond program is focud on the detection mate-rial and more specifically antimonide bad compound miconductor(ABCS)materials which are the basic tech-nology for future detectors at S
CD[7–9].This technology which us epitaxial thin film growth in SCD’s MBE ma-chine enables band gap engineering of the detection mate-rial and the design and optimization of various structures for high operating temperature,a small pitch size and multi-colour detection.The first product of this program is bad on an epitaxial InSb film grown on top of an InSb substrate,enabling an operating temperature above90K with the same performance as achieved with implanted pla-nar InSb at80K.The cond product,bad on InAlSb film with a4.8micron cut-off,was first introduced this year at the Orlando SPIE conference,operating inside a camera at a temperature of100K.
This year SCD is introducing the first detector with a 15-µm pitch and a format of640×512.SCD's future prod-ucts will integrate all the technologies together in the same ,digital signal processor bonded to antimonide array.
In this paper,we describe the technology and the prod-ucts in the prent and future both for MWIR and for LWIR detection.First,the basic concept and the products of the Sebastian range of detectors will be described.Then, the technology and characterization results of the ABCS program will be prented and future plans will be de-scribed.
内聚力2.SCD MWIR .PA roadmapleap
Two dimensional focal plane arrays bad on InSb photodiodes bonded to a CMOS readout circuit have been produced in SCD since1997.The basic InSb technology consists of planar ion implanted photodiodes,hybridized to a Si focal plane processor(FPP)by means of indium bumps,and then backside thinned with surface passivation and anti-reflection coating.The roadmap of the two dimen-sional FPAs is described in Fig.1.Three FPAs for the mid format with30-µm pitch were developed,two of them are bad on SCD signal processors(Gemini and Blue Fairy [10])and one is bad on an Indigo signal processor.Since 2000SCD has been producing larger format FPAs with 640×512elements and smaller pitch,in which the first two FPAs are bad on Indigo ROICs with25-or20-µm pitches.Since2003SCD has been producing the Sebastian detector which is bad on SCD's digital signal processor which has a20-µm pitch.This detector will be described in more detail in the following ction.In order to improve the resolution of the mid format detectors(320×256,30-µm pitch)SCD has been developing two types of detector which have exactly the same active area as the mid format. The first one belongs to the Sebastian family and has been produced since2004.It has a format of480×384elements
Fig.1.SCD MWIR2-D FPA roadmap.
with a20-µm pitch.The cond one has a format of 640×512elements with a15-µm pitch.Prototypes of the detectors which are bad on the Indigo signal processor ISC0402will be available this year,
epadand a detector which is bad on SCD's digital signal processor will be available next year.Bad on the15-µm technology,SCD will in the future develop detectors with larger formats,such as 1000×1000.In parallel to all the activities,SCD is devel-oping the new technology of the ABCS program which will be described in detail below This year we introduced the first prototypes of InAlSb(with4.8-µm cut-off)bonded to a Blue Fairy signal processor operating at a temperature of 100K and integrated inside a hand held camera.By the end of the year,prototypes of InAlSb bonded to Sebastian480 will be available.In the near future(2006),a detector with an operation temperature above130K will be developed, and this detector will have a cut-off of4.2µm.On the basis of the technologies a bi/multi-colour detector can be de-signed for the3–5µm regime.For the long term,bad on the technology of MBE epitaxial thin films and ABCS, InAs/InGaSb superlattice structures can be designed for any wavelength of operation starting from3µm,including 2dimensional arrays for the MWIR and LWIR regimes.
3.SCD LWIR .PA roadmap
During the90's,SCD started the development of backside illuminated detectors which are bad on Hg1–x Cd x Te (MCT)for detection in the8–12µm regime.The MCT detectors are flip-chip bonded to a signal processor located on the FPA.The technology is bad on liquid pha epitaxial(LPE)gro
wth of a MCT layer on a CdZnTe (CZT)substrate and implantation of photodiodes into the epitaxial MCT layer.The first product of this program is a linear array of256×1elements which consists of two rows of photovoltaic elements for redundancy.The first proto-type of this detector was supplied in1996and during the current decade this detector has been produced in high vol-ume with about5,000detectors in the field.On the basis of the photovoltaic MCT technology a time delay integration (TDI)detector was developed at SCD,this detector consist-ing of480×6elements which enables the operation of 480×4at the system level(the four good diodes are chon out of six)with improved signal to noi for each channel. The480×6element TDI detector was integrated success-fully into a scanning system demonstrating a high level of performance with high image resolution on the system level.During2004SCD finished the development of a smaller format TDI detector with288×4elements.
During2002,SCD started to develop a micro-bolo-meter detector which is bad on VO x technology.Re-cently,SCD has demonstrated its first prototype of an uncooled detector which is bad on VO x technology.It is bad on a format of384×288elements,with a pitch of25µm and it exhibits a typical NETD of50mK at F/1[11].In addition to its high level of radiometric performance,this detector has two unique features,power-save mode for low power consumption and on-line signal dri
ft compensation due to ambient temperature changes,which reduces the need for frequent one point corrections.
Fig.2.SCD LWIR FPA roadmap.
Since2003SCD has been producing detectors which are bad on quantum well infrared photo-detector(QWIP) structures for LWIR detection,according to customer de-mands.SCD buys the QWIP chip from suppliers,bonds it to a signal processor and integrates in into a Dewar.Bad on the ABCS program,SCD is planning to implement fu-ture LWIR two dimension arrays with a superlattice made of periodic InAs/InGaSb layers.This device enables the de-sign of detectors which are nsitive to wavelengths from 3µm up to>14µm.
4.SCD digital detectors
what you wanna be
During2003SCD completed the development of the first detector which is bad on a digital signal processor on the focal plane array(FPA)itlf.The main challenge in de-signing a high performance signal processor for a cooled IR detector with digital output was to maintain power con-sumption similar to that in an analogue processor.Predic-tions showed that the conventional design for analogue to digital conversion(ADC)results in power consumption over1W under the operation conditions of a standard IR detector.However,the special design at SCD of the ADC and the whole signal processor has resulted in a power con-sumption of the digital signal processor which is even lower compared to existing analogue processors.
Detectors bad on a digital FPA are considered to be very attractive due to their many advantages over detectors with an analogue FPA,which are expresd especially on the system level.The include:
在线英语阅读助手•lower level of readout noi due to immunity of the an-alogue signal to external noi,
•higher linearity,
•less nsitivity to external ambient conditions,•higher long term stability of the residual non uniformity (RNU),
•removal of the requirement to develop low noi elec-tronics in the system,
•distance between the detector and the system electron-ics can be incread up to veral meters without per-formance degradations,
•integration of the detector into the system is much sim-pler and faster.
Over the past two years we have prented at the spring-time SPIE conferences two types of our digital detector (Sebastian).The first one with a format of640×512in2003 and the cond one with th
e format of480×384in2004.All the above advantages of digital detectors were demonstrated by the performance measured on the Sebastian detectors.
In this ction we prent the general structure of the signal processor and its main features,together with some typical performance results that were measured.
4.1.D3C basic structure
The digital focal plane processor(DFPP)is fabricated with a0.5µm double-poly,triple metal CMOS process and it consists of4.5million transistors.The basic appearance of the digital detector Dewar cooler(D3C)with its proximity card is shown in Fig.3.A special proximity electronics board was developed for this detector,which consists of a FPGA with a local oscillator.The basic arrangement is shown in Fig.3,where the FPGA operates the DFPP di-rectly,collects the data from the DFPP,formats it and nds it out to the system.All other system operation modes are controlled by the system via the communication channel including timing of operation.The interface be-tween the FPGA and the system can either be camera link),or specific as per system requirements.This concept of a simple interface between the D3C and the sys-tem leads to easy and fast integration of the D3C into the system.
4.2.D3C performance
The special design of the signal processor yields an excel-lent linearity of less than0.01%deviation/full range over a regime that starts at2%and continues to90%well-fill ca-pacity.A direct outcome of this high linearity is a low RNU which is less than0.015%std/DR for a range of 2–90%well fill capacity.Figure4shows the linear rela-tionship between the squared measured noi and the signal which testifies to the clean sampling of the signal inside the FPA due to the onboard A/D conversion in the FPA.
The low level of the total noi achieved with SCD's digital detector enables the attainment of a very good sys-tem NETD of10mK for50%well fill capacity.Com-paring the spatial and the temporal noi a similar value of 10mK is achieved in SCD's Digital detectors.The diver-sity of modes together with the direct control of the FPGA on the detector enables various operational modes which are not available for analogue detectors.For example,the detector can be operated with different integration times for each frame(elaboration of combined mode)where the length and timing of the integration can be changed from frame to frame regardless of the previous frame.The detec-tor can also be operated with multiple integration puls in the same frame with a pixel saturation level control,this mode enables high dynamic range together with high frame rate detector operation.A TDI mode of o
peration is also available in the detector with control of the TDI depth to allow operation at different speeds.
Fig.3.Block diagram of system-proxy-detector.
4.3.Main features
In Sebastian,the conversion resolution is controlled exter-nally and can be changed continuously from12–15bits. There is a trade off between the conversion resolution and the maximum frame rate,such that a higher frame rate can be achieved with lower resolution.An anti-blooming cir-cuit was implemented at the input stage of the signal pro-cessor to avoid a very strong light source from disrupting its operation.All the detectors contain a correlated double sampling(CDS)mechanism insid
e the signal processor, where the CDS data is read outside and is subtracted from the video data.The u of CDS during operation was found to be very uful for low frequency noi reduction and for NUC stability enlargement.The pixel binning mode is a connection of every two or four adjacent pixels together, which is done inside the signal processor.This feature en-ables operation with an effective pixel size of20×40,40×20or40×40µm.This mode is very uful while trying to detect a sub pixel target where the image is smeared over four pixels(due to the diffraction limitation of the optics) and the signal is very weak.By applying the four pixels merging function the signal to noi improves significantly, compared to the ca where an external addition of the data is done at the digital level of the image processing.In the following table there is a comparison between the main features of the two Sebastian detectors and Blue Fairy.
All the features combined with a high level of perfor-mance at the system level,make the Blue Fairy and Sebastian detectors the ideal solution for missile warning systems(MWS)[12].
5.Antimonide bad detectors
5.1.Introduction
Going beyond the systems described above,SCD's3rd gen-eration programme is bad on epitaxial
diode materials. The materials have the potential for higher operating temperatures and multi-band detection.They belong to the antimonide bad compound miconductor(ABCS)fam-ily of III-V materials and are bad on InAlSb and InAsSb alloys and InAs/InGaSb superlattices.To cover the MWIR atmospheric window,we recently propod[7]the epitaxial alloys:InAs1–y Sb y on GaSb with0.07<y<0.11 and In1–z Al z Sb on InSb with0<z<0.03.The can be ud together with superlattices bad on thin layers of InAs and InGaSb that provide the basis for detector materi-als operating also in the8–12µm long wavelength infra-red (LWIR)atmospheric window as well as in the MWIR[13]. For the alloys,there can be a small lattice mismatch be-tween the alloy and the substrate material,and this can lead to the generation of dislocations inside the alloy.It is there-fore necessary to find a strategy to suppress the effect of the dislocations so that they are not harmful to detector op-eration.On the other hand superlattices,in principle,offer
Fig.4.Squared noi versus signal measurement.
Table1.The main features of the Blue Fairy and Sebastian detectors.
Feature Blue Fairy Sebastian480Sebastian640 Format320×256480×384640×512 Full range(gain)Me– 3.5/7/11/15/22/301/3/7/10/143/7/10/14
Frame rate@full frame>450Hz>160Hz@15bit
>240Hz@13bit
>280Hz@12bit >120Hz@15bit >160Hz@13bit >180Hz@12bit
Main integration modes ITR/IWR/combined ITR/IWR/combined/multistep/multiple Readout dilution——every2nd and6th row every2nd row Pixel binning——1×2,2×1,2×2
Linearity<0.05%@2–90%WF<0.01%@2–90%WF
RNU std/dr<0.025%@2–90%WF<0.015%@2–90%WF
InSb bias operating point500pA–1µA70pA–100nA70pA–100nA Windowing every2rows/16columns e对不起英文怎么写
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