CMOS: The Next Generation CTD for ICP-OES · 2020-04-03 · Analog Video Out. Serial Commands. USB...

CMOS: The Next Generation CTD for ICP-OES

Manny AlmeidaTeledyne Leeman Labs

Mason, OH

Outline

■ Detectors in ICP-OES■ New CMOS Detector■ Performance

Detectors In ICP-OES

■ Photomultiplier Tubes (PMTs)■ Charge Transfer Devices

― Charge Coupled Device (CCD)― Charge Injection Device (CID)

Photomultiplier Tubes (PMTs)■ Original detector used in ICP■ Close to the ideal single

channel detector■ Linear with wide dynamic

range (108)■ Absence of read noise■ Low dark current■ High Gain (106)

■ Relatively short integration time

Photomultiplier Tubes (PMTs)

■ High cost per channel■ Limited number of channels■ Costly field upgrade■ Severely limited wavelength

coverage (cannot capture entire spectrum)

■ Non-simultaneous background correction

Charge Transfer Devices – What Are They?

■ 2 dimensional solid state array detector

■ Consist of some number of pixels (~70k – 4M)

■ Small Size (≤ 28 x 28 mm)■ High Quantum Efficiencies

■ But no signal multiplication■ Low dark current (when

cooled, ~35oC)

Charge Transfer Devices – Why?■ Complete wavelength flexibility

■ Simple to add needed wavelength to a method

■ Simultaneous measurement■ Internal standard■ Interfering Element Correction

■ Simultaneous background correction

■ Simplifies manufacturing■ All optical systems are the same

Echelle Grating Dispersion

Eche

lle G

ratin

g O

rder

s (~

70 –

145)

Prism

Disp

ersio

n

Charge Transfer Devices■ Charge Coupled Device (CCD)

― Invented in 1969 at Bell Labs■ Charge Injection Device (CID)

― Invented in 1972 at General Electric Corporate Research Center■ CMOS

― Invented in 1963 at Fairchild Semiconductor■ First commercial use as ICP-OES detectors in early 1990s

How They Work■ Incident photons generate

electron-hole pairs■ In a CCD, applied potential at

gate forces ELECTRONS to collect in the potential well

■ In a CID, applied potential at gate forces HOLES to collect in the potential well

■ How the charge is then handled depends on the detector type

Charge Handling■ CCDs require serially reading the entire array

destructively.― No Random Access Integration (RAI)― No Non Destructive Read Out (NRDO)

■ CIDs allow nondestructive readout of the integration at each pixel, reading then rapidly resetting the charge well to zero when it approaches full well.

Charge Handling - CID■ CIDs do not need to move

charge very far■ Each pixel contains charge

collection and measuring circuitry

■ The amount of charge can be monitored during the collection phase■ Non-Destructive Readouts (NDRO)

■ Individual pixels can be accessed■ Random Access Integrations (RAI)

Charge Handling - CID■ CIDs do not need to move

charge very far■ Each pixel contains charge

collection and measuring circuitry

■ The amount of charge can be monitored during the collection phase■ Permits non-destructive readouts

■ Individual pixels can be accessed■ Permits random access integrations

Charge Handling - CCD

■ The charge from each pixel is brought to a single point to be measured

Charge Handling - CCD


CCD or CID?■ Teledyne Leeman Labs introduced its first CTD

based ICP-OES in 2001■ Choose the CID technology (L-PAD)

― NDRO― RAI― Larger Format Detector (28 x 28mm)

The Next Generation■ ICP-OES has been using the same Charge Transfer Devices

(CTDs) for ~27 years■ Until now, no new imagers have been developed■ Scientific imagers are special.

― good Quantum Efficiency (QE) from 165 to 900 nm ― dynamic range of 108,― noise characteristics that are low.

■ Scientific imagers are low volume devices and are not greatly influenced by the mass market

■ Consumer devices drive imager technology down a significantly different path from scientific imagers.

The Next Generation■ For Leeman Labs’ latest generation of ICP-OES instruments,

the Prodigy7 and Prodigy Plus, we wanted to develop the next generation CTD imager

― Significant investment of resources and money■ We collaborated with Teledyne Scientific and Imaging to

design― A detector with state-of-art technology― Optimized for ICP-OES― Based on CMOS technology

■ CMOS is the detector technology of the future

Detector Requirements for ICP-OES■ Sensitivity

― Detection Limits■ Dynamic Range

― Readout speed― Full-well capacity

■ Resolution― Pixel size vs. full well capacity vs. dynamic range

■ Precision ― Short-Term and Long-Term Stability

■ Speed ― Sample Throughput

■ Wavelength Coverage― Quantum Efficiency

What is CMOS?■ What is CMOS?

― Complementary Metal Oxide Semiconductor

■ Have significant share of commercial sensor market

― Appear in consumer devices

■ After years of development, CMOS devices now have

performance levels exceeding CCDs

― With additional advantages

Why CMOS?■ Large Number of Manufacturing Sites

― Same resources as microchip o Cost efficient production

― Highly mature process technologyo High quality

■ High level of flexibility― Allowed customization for ICP-OES

■ On chip circuitry provides many processing functions― Fast

■ Pixels can be read individually― Multiple reads to reduce noise

Why CMOS?

■ CMOS device can be scanned in different ways

― Analysis

― Full Frames

■ Prodigy7 and Prodigy Plus is the first ICP to use CMOS detector technology

■ CMOS is the detector technology for the future

Camera System■ Camera consists of 3 major blocks

― Front-side monolithic CMOS imagero Lumogen coating for UV response

― Camera Electronicso Housing PCBo Drive & Acquisition PCBo Firmware

― Host PC w/ software■ Cost of rework and design iterations are highest for imager and lowest for software, therefore

― Functionality was moved from FPA to firmware where possible― Functionality was moved from firmware to software where possible

Host PC Software Focal Plan Array (FPA)

Low Level Camera

Electronics

Analog Video Out

Serial Commands

USB I/F

3-T Pixel with Analog Readout

• High Full Well Capacity• High Speed Readout

Prodigy7 Detector

■ Designed exclusively for Prodigy7 and Prodigy Plus

■ CMOS Technology

■ 28 x 28 mm

■ 1840 x 1840 pixels■ 3.38M

■ Pre-amp per pixel

■ 15 µm pixel size

Prodigy7 Detector■ 40x faster readout than L-PAD

■ Improves Linearity

■ Sample Throughput

■ Faster Analysis times■ Can read up to 256 wavelengths in

single method

■ USB Communication■ 480 Mbit/sec

CMOS Comparison with L-PADProdigy7 Prodigy CID

Size, mm 28 x 28 28 x 28 15 x 15

# pixels1840 x 1840

3.38M1024 x 0124

1.05M540 x 540

292k

Pixel size, µm 15 x 15 27 x 27 27 x 27

Full Well Capacity, e- 150,000(667/ µm2)

400,000(550/ µm2)

400,000(550/ µm2)

Noise per read, e- 30 300 300

Data Read Speed, MHz 2 0.05 0.05

L-PAD and CMOS Pixels

Pixel Electronics

15 µm

CMOS Pixel

27 µm

Row electrode

Column Electrode

L-PAD PixelPhotoactive Area

Detector Modes■ Detector will operate in two basic modes:■ Full frame mode

■ Entire array is read out■ Array may be split into row based

windows with different integration times

■ Random access mode■ Sub arrays are read out sequentially

using NDRO■ When well fills up in a sub-window

the sub-window is reset and reading resumes

ROI ModeFull Frame Mode

CMOS Camera

How the L-Pad Worked■ Interrogate ROI (3x3) to see how many e- in pixel 2 sec pre-exposure■ Determines how often a subarray must be monitored to prevent

saturation― And to make as few reads as possible

Programmableintegration widthand background

widths.

Pixel # (wavelength)

Sign

al(c

ps)

As (I) 189.042 nm

Time (s)

Sign

al (c

ount

s)

ExposureTime

ThresholdSaturation

Strong and weak emissions read simultaneously

for entire integration time

How the L-Pad Worked■ At the end of the integration, clean up read is

done■ Depending on the level left over, a certain number

of NDROs is done (Non Destructive Read Out)― 256, 128, 64, 32, 16, 8, 4, 2

■ Done to reduce the read noise of 300e-

― Read noise is ~26e- @ 128 NDROs

How the CMOS Detector Works■ Each wavelength has a subarray

on the detector■ During analysis, the detector

simultaneously monitors the intensity of all pixels in the subarrays using NDRO and RAI

■ Once the intensity reaches 85% of saturation, the pixel is reset and the integration begins again

How the CMOS Detector Works■ Can operate the new CMOS detector like the L-PAD

― Random Access

― Non Destructive Read Out

■ The L-PAD is operated the way it is because it is relatively slow.

■ The CMOS is operated the way it is because it is very fast― Simpler operation

How the CMOS Detector Works■ Not necessary to sort the subarrays by intensity

― No pre exposure

― The CMOS runs as fast as possible (15 ms)

o More reads means less read noise ( # 𝑜𝑜𝑜𝑜 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟)

■ CMOS still monitors pixels to see if they at above threshold

― But ALL pixels in the subarray, not just the ones in the ROI

L-PAD CMOS

How the CMOS Detector Works

■ The detector takes a reading of every pixel in every subarray every 15 ms

■ In a 30 sec integration, there will be 2000 readings of each subarray

■ “Stacks” the intensities measured every 0.025 sec

How the CMOS Detector Works■ All the

readings

stacked

■ Slope

determined

by linear

regression0

500

1000

1500

2000

2500

3000

3500

4000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

How the CMOS Detector Works■ Following example will show how the CMOS

detector deals with lines of differing intensities― Intensity Mn257 > Ba493 > Cu324 ― 2.5 s total integration― Using

o Random Access Integration (RAI)o Non-Destructive Read Out (NRDO) every 15 ms

Reach Threshold

Mn257 nmBegin

Integration

Collect Intensities

(NDRO)

Reset

Integration Time, s

Inte

nsity

Collect Intensities

(NDRO)

Reach Threshold

Reset

Ba453 nmBegin

Integration

Collect Intensities

(NDRO)

Reach Threshold

Reset

Integration Time, s

Inte

nsity

Cu324 nmBegin

Integration Collect Intensities

(NDRO)

Integration Time, s

Inte

nsity

No Reset

Integration Time, s

Inte

nsity

Performance

Read Noise ComparisonL-PAD (CID) CMOS

NDRO Noise, e- NDRO Noise, e- Integration Time, sec

256 18.8 2000 0.67 30128 26.5 1000 0.95 1564 37.5 500 1.34 7.532 53.0 250 1.90 3.816 75.0 125.0 2.68 1.98 106.1 62.5 3.79 0.94 150.0 31.3 5.37 0.52 212.1 15.6 7.59 0.21 300.0 7.8 10.73 0.1

3.9 15.18 0.0592.0 21.47 0.0291.0 30.36 0.015

CMOS vs. L-PAD Read Noise

18.826.5

37.553.0

75.0

106.1

150.0

212.1

300.0

1.902.683.795.377.59

0

50

100

150

200

250

300

350

0 50 100 150 200 250 300

Read

Noi

se, e

-

Non-Destructive Reads, (NRDO)

L-PAD

CMOS

Lower Noise means the detector can be run at higher temperature without degrading detection limits

Prodigy7 Linear Ranges (200.7)

Prodigy Prodigy7As 10 200Sb 10 400Cd 10 60Cr 10 100

Mo 100 200Tl 100 300P 1000 3000

CMOS vs L-PAD Data Transfer time

26 28

45

79

96

109

120

128

1 1 1 1 1 1 1 1

0

20

40

60

80

100

120

140

10 20 40 80 100 120 140 155

Data

Tra

nsfe

r Tim

e, s

ec

Number of Wavelengths in Method (@ 100ppm)

L-PAD

CMOS

The fast readout out speed means sample analysis time depends on the integration, sample uptake and rinse time.

Prodigy 7 12 Hour Stability (Radial)Mean SD RSD

As 189.042 3.94 0.05 1.38Be 313.042 4.00 0.04 0.95Ca 317.933 3.93 0.04 1.01Cd 214.441 3.88 0.05 1.30Co 228.615 3.96 0.04 1.13Cr 267.716 3.95 0.03 0.88Cu 324.754 3.95 0.04 1.04Fe 259.940 3.96 0.04 0.99Mg 285.213 3.93 0.03 0.86Mn 257.610 3.92 0.03 0.85Mo 277.540 3.96 0.04 0.90Ni 231.604 3.90 0.04 1.12Sb 206.833 3.94 0.04 1.05Se 196.090 4.06 0.05 1.33Ti 334.941 3.96 0.04 0.89Tl 190.856 3.94 0.06 1.59V 292.401 3.97 0.04 0.88Zn 213.856 3.90 0.05 1.31

Performance (ppb)Element Prodigy7 Prodigy ImprovementAl 167 0.3 0.6 2.0As 189 4.0 4.4 1.1Tl 189 1.9 2.7 1.4As 193 3.0 5.8 1.9Se 196 3.2 6 1.9Sb 206 2.8 3.1 1.1Pb 220 1.2 1.9 1.6

Note: Low flow torch running at 12 L/min detection limits

Teledyne Leeman Detector■ CMOS Detector Characteristics

― Low Readout Noise― Greater Full Well Capacity― Greater Speed ― Simultaneous Measurement― Random Access Integration (RAI)― Non-Destructive ReadOut (NDRO)

Teledyne Leeman Detector■ The Teledyne CMOS detector is the next generation device■ All data collected simultaneously

― Peak― Background― Internal Standard and Interfering Element Corrections

■ All wavelengths get the same integration time■ Strong and weak lines measured at the same time■ Greater speed

― Better linearity― Faster sample throughput resulting in lower cost of analysis.

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CMOS: The Next Generation CTD for ICP-OES · 2020-04-03 · Analog Video Out. Serial Commands. USB...

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Transcript of CMOS: The Next Generation CTD for ICP-OES · 2020-04-03 · Analog Video Out. Serial Commands. USB...