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Model 4200A-SCS Source-Measure Unit (SMU) User's Manual

Section 5: Source-measure concepts

4200A-SMU-900-01 Rev. A December 2020

5-11

4200-SMU and 4201-SMU sink boundaries

Nominal 4200-SMU and 4201-SMU boundaries are shown in the following figure. Note that actual

boundaries are 210 V at 10.5 mA or 21 V at 105 mA.

Figure 79: 4200-SMU or 4201-SMU with a 4200-PA operating boundaries

Summary of Contents for Keithley 4200-SMU

Page 1: ...User s Manual 4200A SMU 900 01 Rev A December 2020 P4200A SMU 900 01A 4200A SMU 900 01A tek com keithley Model 4200A SCS Source Measure Unit SMU...

Page 2: ...Source Measure Unit SMU User s Manual Model 4200A SCS...

Page 3: ...Instruments product names are trademarks or registered trademarks of Keithley Instruments LLC Other brand names are trademarks or registered trademarks of their respective holders Actuate Copyright 1...

Page 4: ...d to mains These instruments will be marked as category II or higher Unless explicitly allowed in the specifications operating manual and instrument labels do not connect any instrument to mains Exerc...

Page 5: ...lains hazards that could damage the instrument Such damage may invalidate the warranty The CAUTION heading with the symbol in the user documentation explains hazards that could result in moderate or m...

Page 6: ...ure a simple test 3 3 Set the key parameters 3 5 Set the test parameters 3 6 Run a simple test 3 8 Operation Mode SMU 3 9 Open operation mode SMU 3 10 Voltage Bias operation mode 3 10 Voltage Linear S...

Page 7: ...voltage sweep 3 26 Stop step 3 27 Stop sweep 3 27 Voltage Report Voltage 3 27 Voltage Range 3 27 SMU Test Settings 3 27 Speed 3 27 Report Timestamps 3 28 Delay Factor 3 29 Filter Factor 3 30 Auto A D...

Page 8: ...ture guarding 5 4 Local and remote sensing 5 5 Local sensing 5 7 Remote sensing 5 8 Source or sink 5 8 4200 SMU and 4201 SMU source or sink 5 9 4210 SMU or 4211 SMU source or sink 5 10 4200 SMU and 42...

Page 9: ...ectrostatic interference 6 11 Radio frequency interference 6 11 Ground loops and other SMU grounding considerations 6 12 Make I V measurements on a solar cell 7 1 Introduction 7 1 Equipment required 7...

Page 10: ...for each mode and the SMU test settings Source measure hardware on page 4 1 Provides information about the SMUs and related instruments including 4200 PAs and ground units and provides information So...

Page 11: ...age Maximum current Maximum power 4200 SMU 4201 SMU 210 V 105 mA 2 2 W 4210 SMU 4211 SMU 210 V 1 05 A 22 W Preamplifier A 4200 PA preamplifier adds five low current source measure ranges to a SMU With...

Page 12: ...sult in personal injury or death Asserting the interlock allows the SMU and preamplifier terminals to become hazardous exposing the user to possible electrical shock that could result in personal inju...

Page 13: ...nates these errors When using more than one SMU use the ground unit for circuit COMMON connections instead of the outer shield of the SMU terminals Refer to Using the ground unit on page 2 12 Do not t...

Page 14: ...the DUT test fixture or probe station Figure 1 Triaxial cable 4200 TRX X If your system does not have preamplifiers installed use the cables that have a miniature triaxial connector on one end and a s...

Page 15: ...of the SMU is used to apply voltage or current to the device The FORCE terminal or ground unit can also be used to connect the device terminal to the COMMON circuit The following figure shows typical...

Page 16: ...minal and 4 terminal devices Notice that only the FORCE HI terminal of each SMU is connected to the device terminal FORCE HI is the center conductor of the triaxial cable Connecting the SMU or ground...

Page 17: ...by electrostatic interference parasitic capacitance system leakage currents and so forth See Guarding on page 5 1 for more information on the principles and advantages of guarding A safety shield mus...

Page 18: ...Model 4200A SCS Source Measure Unit SMU User s Manual Section 2 Connections and configuration 4200A SMU 900 01 Rev A December 2020 2 7 Figure 8 Device shielding Figure 9 Device shielding basic circuit...

Page 19: ...asure Unit SMU User s Manual 2 8 4200A SMU 900 01 Rev A December 2020 To guard the device connect the DUT shield to GUARD GUARD is the inner shield of triaxial cable as shown in the following figure F...

Page 20: ...or the Keithley Instruments Low Level Measurements Handbook for more information about measurement integrity Using the ground unit with more than two SMUs Use the ground unit for circuit COMMON conne...

Page 21: ...Connections and configuration Model 4200A SCS Source Measure Unit SMU User s Manual 2 10 4200A SMU 900 01 Rev A December 2020 Figure 12 Typical SMU connections Figure 13 Typical SMU COMMON connections...

Page 22: ...al cable to make your connections as follows Connect preamplifier FORCE center conductor of FORCE terminal to DUT HI Connect signal COMMON outer shield of FORCE terminal to DUT LO When using more than...

Page 23: ...s it can also be used for circuit COMMON connections when using only one SMU Ground unit and SMU local sense connections The following figure shows typical local sense connections using two SMUs two D...

Page 24: ...ections Ground unit and preamplifier local sense connections The following figure shows typical local sense connections using two preamplifiers two DUTs and the ground unit Make connections as follows...

Page 25: ...fier local sense connections schematic Ground unit and preamplifier remote sense connections The following figure shows typical remote sense connections using two preamplifiers two DUTs and the ground...

Page 26: ...MU User s Manual Section 2 Connections and configuration 4200A SMU 900 01 Rev A December 2020 2 15 Figure 20 Ground unit and preamplifier remote sense connections Figure 21 Ground unit and preamplifie...

Page 27: ...tage or current source in series with a current meter connected in parallel with a voltage meter The voltage limit V limit and current limit I limit circuits limit the voltage or current to the progra...

Page 28: ...MU and preamplifier terminals to become hazardous exposing the user to possible electrical shock that could result in personal injury or death SMU and preamplifier terminals should be considered hazar...

Page 29: ...n a single 4200A SCS to the DUT SENSE terminal The SENSE terminal is a miniature triaxial connector used to apply the SMU SENSE signal to the DUT in a remote sense application when the preamplifier is...

Page 30: ...either be mounted and connected directly to the SMU or it can be connected to the SMU using a cable 4200 RPC X when mounted remotely Refer to the Source measure unit SMU with 4200 PA overview on page...

Page 31: ...0A SCS is asserted the FORCE and GUARD terminals of the SMUs and preamplifier should be considered to be at high voltage even if they are programmed to a nonhazardous voltage current Testing with less...

Page 32: ...t be taken to prevent a shock hazard by surrounding the test device and any unprotected leads wiring with double insulation that is rated for 250 V Category O If voltages greater than 20 V are require...

Page 33: ...test fixture or probe station Figure 26 Triaxial cable 4200 TRX X If your system does not have preamplifiers installed use the cables that have a miniature triaxial connector on one end and a standar...

Page 34: ...as devices and tests The order of operations of a test is determined by the order and selection of items in the project tree The following topics describe how to set up and run a simple project using...

Page 35: ...28 Filter and search for the bjt project Add a device and test to the project You can add additional items to a project When you add a project from the library to the project tree it is copied from t...

Page 36: ...he project If the device for a test is not in the project tree Clarius adds the appropriate device when you add a test to the project tree You can also add the device and test separately Configure a s...

Page 37: ...for each terminal are displayed near the terminal The key parameters include The type of terminal such as gate drain source or collector The instrument that is attached to the terminal You assign the...

Page 38: ...hange 2 If there is a Down arrow to the right of the field Select a value from the list Field Type the value Error messages are displayed if you type an out of range value Check box Select or clear th...

Page 39: ...s pane you can set items such as Test speed Timestamp reporting Delays Hold times In test and post test data computations using the Formulator Refer to Formulator in the Model 4200A SCS Clarius User s...

Page 40: ...7 To set up test parameters 1 In the project tree select the test 2 Select Configure 3 Select Test Settings in the right pane Figure 33 Test Settings for a SMU test 4 Adjust settings as needed 5 If n...

Page 41: ...n the project tree are executed from top to bottom in the project tree If you want to run an entire project make sure the project name is highlighted Running a project saves the configuration settings...

Page 42: ...ect the project 3 Select Run 4 Select Analyze to view the results To abort a test select Stop All test and action execution stops immediately Operation Mode SMU The operation mode determines what type...

Page 43: ...cannot set any parameters when the Open operation mode is selected Voltage Bias operation mode The Voltage Bias operation mode maintains a selected constant voltage state at the terminal subject to a...

Page 44: ...hat is recorded in the Analyze pane Voltage Segment Sweep operation mode When you select the Voltage Segment Sweep operation mode the test increments through a series of constant voltage steps You can...

Page 45: ...to avoid overheating of sensitive devices The following figure illustrates a possible list sweep Figure 39 Example list sweep The voltage sweep generates parametric curve data that is recorded in the...

Page 46: ...o complete a sweep For each step parametric curve data is generated The data is recorded in the Analyze pane Figure 41 Stepping the gate voltage of a FET Current Bias operation mode Current Bias opera...

Page 47: ...rrent sweep is shown in the following figure Figure 42 Example multisegment current sweep Current List Sweep operation mode SMU The Current List Sweep operation mode allows you to customize the curren...

Page 48: ...ic curve data that is recorded in the Analyze pane Current Log Sweep operation mode SMU The Current Log Sweep operation mode allows you to sweep over a large range and plot the measurements on a logar...

Page 49: ...The 4200 SMU and 4201 SMU each have a compliance of 105 mA The 4210 SMU and 4211 SMU each have a compliance of 1 05 A You cannot set any parameters for the Common operation mode SMU all terminal para...

Page 50: ...ge that is more than that limit This limit is called compliance and helps prevent damage to the device under test DUT The SMU will not exceed the maximum limit set for compliance When a SMU is acting...

Page 51: ...cannot exceed 10 mA and the voltage across the resistance is limited to 100 mV In effect the 10 V voltage source is transformed into a 10 mA current source In steady state conditions the set complian...

Page 52: ...to open a dialog box in which you can type the current or voltage level for each step of the sweep in the rows You can type any valid instrument current or voltage You can select a value or multiple...

Page 53: ...the instrument is on To prevent damage to the device under test or external circuitry do not set the voltage source to levels that exceed the value that is set for overvoltage protection Asserting th...

Page 54: ...ence for the SMUs is 1 SMU1 powers on 2 50 ms delay 3 SMU2 powers on 4 100 ms delay 5 SMU3 powers on You can set the delay from 0 to 1 0 s For information on changing the sequence refer to SMU Power O...

Page 55: ...sition to the off time During pulse off time the pulse output returns to the specified Base Voltage level After the off time expires the output returns to 0 V Figure 47 Pulse Mode example Voltage bias...

Page 56: ...ent range as the test progresses This option provides the best resolution when the measurements span several decades However time delays can occur with range changes that can limit the measurement spe...

Page 57: ...ded voltage values are actual measured values For example if you specified a current of 10 mA the actual measured value such as 9 9982 mA is recorded The Measured mode increases the measurement time b...

Page 58: ...p value that is larger than the stop value Use a step value that does not result in a fractional number of points If the point is fractional the step value is forced to a value that results in a whole...

Page 59: ...lue of 4 333 In this case the Step value is forced to 0 001 A which results in four data points at 0 A 0 0015 A 0 0030 A and 0 0045 A Step voltage sweep The voltage size of each step of the sweep The...

Page 60: ...ly selects a single measurement range based on the current or voltage compliance value Specific ranges You can select a fixed measurement range from a list SMU Test Settings The settings that are avai...

Page 61: ...s placed in the Analyze sheet in the same row as the measurement Each elapsed time is measured relative to the beginning of the test when voltage or current is first applied to the device If Clarius r...

Page 62: ...for a delay time before making a measurement The delay time allows for source settling The Delay Factor adjusts the delay time for the selected speed It is fixed for Fast Normal and Quiet speeds If yo...

Page 63: ...h as the Keithley 7174A High Speed Low Leakage Current Matrix you should not need to increase the Delay Factor by more than two times Filter Factor To reduce measurement noise each 4200A SCS applies f...

Page 64: ...Filter Factor is not 0 the SMU applies an optimum A D converter time that is based on the Filter Factor setting The applied A D converter time value is never less than the specified A D Aperture Time...

Page 65: ...of Samples Specifies the number of points to be acquired Set the number of samples to a value from 1 to 4096 Hold Time SMU The starting voltages or currents of a sweep may be substantially larger tha...

Page 66: ...he SMU remains in that state To set the output action on completion 1 Select the test 2 Select Configure 3 In the right pane select the Test Settings tab 4 Select Advanced 5 Select or clear Disable Ou...

Page 67: ...the test that is presently being run If there are additional tests operation continues to the next test Device The 4200A SCS exits the device that is presently being run If there are additional device...

Page 68: ...dware overview on page 4 1 Discusses basic circuit configurations for SMUs operating boundaries and connectors Source measure unit SMU with 4200 PA overview on page 4 5 Details how the 4200 PA extends...

Page 69: ...llowing figure The SMU is essentially a voltage or current source in series with a current meter connected in parallel with a voltage meter The voltage limit V limit and current limit I limit circuits...

Page 70: ...about these terminals is summarized below Asserting the interlock allows the SMU and preamplifier terminals to become hazardous exposing the user to possible electrical shock that could result in per...

Page 71: ...axial connector used to apply the SMU SENSE LO signal to the DUT in a full Kelvin remote sense application The center pin is SENSE LO The inner shield is SENSE GUARD The outer shield is circuit COMMON...

Page 72: ...MU senses locally FORCE terminal The FORCE terminal is a miniature triaxial connector used to apply the SMU FORCE signal to the DUT when a preamplifier is not used The center pin is FORCE The inner sh...

Page 73: ...nt source measure capabilities The preamplifier FORCE terminal is connected to DUT HI and DUT LO is connected to COMMON See Basic source measure connections on page 2 1 for more detailed information F...

Page 74: ...orange is enabled the programmed compliance value cannot be set below 100 fA when sourcing voltage or below 20 mV when sourcing current Operating boundaries The four quadrants of operation for the 420...

Page 75: ...these terminals is summarized below Refer to the Basic source measure connections on page 2 1 for additional information regarding making preamplifier signal connections Exposure to electrical shock c...

Page 76: ...the power cord before connecting or disconnecting the preamplifier Failure to do so may result in SMU or preamplifier damage possibly voiding the warranty The maximum allowed voltages between the var...

Page 77: ...FORCE terminal The FORCE terminal is a standard triaxial connector used as a return path for the SMU or preamplifier FORCE current The center pin is FORCE the inner shield is GUARD and the outer shiel...

Page 78: ...and the DUT are eliminated otherwise the SMU will sense locally Preamplifier CONTROL connector The preamplifier CONTROL connector connects to the SMU PA CNTRL connector and provides both power and sig...

Page 79: ...pics describe Basic circuit configurations Connectors Basic characteristics The ground unit shown in the following figure provides convenient access to circuit COMMON which is the measurement ground s...

Page 80: ...it connections The following figure shows how the various GNDU signals are related to the SMU signals The GNDU FORCE signal is circuit COMMON The GNDU SENSE terminal is connected to each SMU SENSE LO...

Page 81: ...se the GNDU with a SMU to make full Kelvin remote sense measurements Similarly the following figure includes the preamplifier As shown in these figures the GNDU FORCE signal provides the return path f...

Page 82: ...about these connectors is summarized below Refer to Basic source measure connections on page 2 1 for additional information about signal connections for ground units The maximum allowed voltage betwe...

Page 83: ...ld is GUARD and the outer shield is circuit COMMON When the ground unit SENSE signal is connected to a DUT all SMU preamplifier measurements are made relative to this DUT connection COMMON terminal Th...

Page 84: ...cycle and provides an overview of sweep waveforms Guarding The purpose of guarding is to eliminate the effects of leakage current and capacitance that can exist between FORCE and COMMON or between SE...

Page 85: ...gh voltage even if they are programmed to a nonhazardous voltage current Guard connections GUARD is available at the inner shield of the FORCE and SENSE triaxial connectors for both the SMU and the pr...

Page 86: ...is effectively in parallel with the DUT creating an unwanted leakage current IL This leakage current may seriously affect readings particularly at low current levels Figure 69 Unguarded circuit In the...

Page 87: ...and the voltage and temperature requirements of the test circuit Connect the enclosure of all metal test fixtures to protective earth safety ground See your specific test fixture for information Nonc...

Page 88: ...he DUT Figure 72 Test fixture guarded The guard signal has an output impedance of 100 k which is effective only when connected to high impedance loads Local and remote sensing The type of sensing loca...

Page 89: ...RCE COMMON to the DUT as shown in the following figure Figure 73 Local sensing overview To use remote sensing connect both SENSE and both FORCE terminals to the DUT as shown in the following figure Fi...

Page 90: ...uring low impedance DUTs the local sensing method may give inaccurate results The cable resistance RC and the connection resistance such as matrix crosspoint resistance or prober to IC pad resistance...

Page 91: ...s negligible the voltage actually measured by the SMU VM is essentially the same as the voltage across the DUT VDUT Figure 76 Remote sensing Source or sink Depending on how they are programmed and wha...

Page 92: ...s set the voltage compliance to a level that is higher than the external voltage level Failure to do so could damage the SMU or preamplifier due to excessive current that will flow into the unit 4200...

Page 93: ...020 4210 SMU or 4211 SMU source or sink In the following figure the 1A 20 V and 100 mA 200 V magnitudes are nominal values The actual maximum output magnitudes of the 4210 SMU and 4211 SMU are 1 05 A...

Page 94: ...4200A SMU 900 01 Rev A December 2020 5 11 4200 SMU and 4201 SMU sink boundaries Nominal 4200 SMU and 4201 SMU boundaries are shown in the following figure Note that actual boundaries are 210 V at 10 5...

Page 95: ...rent source with voltage limit capability that can measure current I Meter or voltage V Meter The compliance circuit limits the output voltage to the programmed value Source I measure V or I For volta...

Page 96: ...e circuit limits the current to the programmed value Sense circuitry is used to continuously monitor the output voltage and adjust the V Source as needed The V Meter senses the voltage at the FORCE an...

Page 97: ...the voltage compliance higher than the measured voltage For measure I set the current compliance higher than the measured current In the following figure the SMU is configured to measure voltage only...

Page 98: ...operation is covered operation in the other three quadrants is similar As shown in the following figure the 4200 SMU or 4201 SMU can output up to 105 mA at 21 V or 10 5 mA at 210 V The 4210 SMU or 42...

Page 99: ...the 2 k load and subsequently measures 20 V As shown the load line for 2 k intersects the 10 mA current source line at 20 V which is below the programmed voltage limit Figure 87 Current source normal...

Page 100: ...is covered operation in the other three quadrants is similar As shown in the following figure the 4200 SMU or 4201 SMU can output up to 21 V at 105 mA or 210 V at 10 5 mA The 4210 SMU or 4211 SMU can...

Page 101: ...urcing 50 V to the 20 k load and subsequently measures 2 5 mA which is within the 5 mA programmed current limit As shown in the following figure the load line for 20 k intersects the 50 V voltage sour...

Page 102: ...source V measure V The SMU can measure the function it is sourcing When sourcing a voltage you can also measure voltage However if you are sourcing current you can also measure the output current For...

Page 103: ...signal The actual delay that is needed can be calculated or determined by trial and error For purely resistive loads and at higher current levels the sweep delay can be set to a minimum The measure t...

Page 104: ...rformed on each step or point of the sweep One measurement is made at each step The time spent at each step depends on how the source delay measure cycle is configured such as the sweep delay setting...

Page 105: ...U User s Manual 5 22 4200A SMU 900 01 Rev A December 2020 Operation mode timing The following figure shows source measure timing for a test system using three SMUs It shows basic timing between the sw...

Page 106: ...range All SMUs in the test system are synchronized so the delay time applied by the most delayed SMU is the delay time applied by all SMUs Sweep Delay SD The sweep delay provides additional settling t...

Page 107: ...y time applied by all SMUs In sampling mode all device terminals are set to a static operation mode Open Common Voltage Bias or Current Bias The range dependent delay may not be needed because a sourc...

Page 108: ...ost never occurs in semiconductor applications A SMU that is sourcing voltage is stable when driving capacitive loads up to 10 nF However at the lower current measurement ranges large capacitive loads...

Page 109: ...d effect transistor FET or bipolar junction transistor BJT can increase system instability The following figure shows an example of BJT characterization curves measured under stable conditions Figure...

Page 110: ...apacitor between the base and emitter of a bipolar junction transistor BJT or between the gate and source of a field effect transistor FET Use a 100 pF to 1000 pF capacitor Eliminating low frequency o...

Page 111: ...e range If necessary set both SMUs to autorange Configure the emitter SMU for the Voltage Bias Operation Mode and set it to 0 V This allows you to configure the current measurement range For the emitt...

Page 112: ...ails Methods to reduce leakage currents include Use good quality insulators such as Teflon or polyethylene in the test fixture Reduce the humidity of the test environment Insulators and the test circu...

Page 113: ...calibrating the system Refer to Calibrate the system in Model 4200A SCS Setup and Maintenance Figure 99 Input offset currents Offset currents can also be generated externally from such sources as tri...

Page 114: ...bench or rigid structure Other solutions to movement and vibration problems include Remove or mechanically decouple vibration sources such as motors pumps and other electromechanical devices Securely...

Page 115: ...ionized DI water wash Dielectric absorption Dielectric absorption in an insulator can occur when a voltage across that insulator causes positive and negative charges within the insulator to polarize W...

Page 116: ...performance there are usually minimum recommended source resistance values based on measurement range The following table summarizes minimum recommended source resistance values for various measuremen...

Page 117: ...quiet are fixed You can also set a custom value To achieve a low noise measurement the quiet setting is recommended The compromise is that measurement speed is slower in comparison to the fast and no...

Page 118: ...use Shielding Possibilities include a shielded room a shielded booth shielding the sensitive circuit test fixture and using shielded cable The shield should usually be connected to a solid connector...

Page 119: ...A SCS signal COMMON and DUT LO to safety earth ground A large ground current flowing in the loop will encounter small resistances either in the conductors or at the connecting points This small resist...

Page 120: ...rical characteristics of the cell These instructions show you how to make connections from the SMU to the solar cell and how to add the forward bias I V test into a new project and automate the measur...

Page 121: ...never connect or disconnect from the 4200A SCS while the output is on To prevent electric shock test connections must be configured such that the user cannot come in contact with test leads conductors...

Page 122: ...he DUT The following figures show the 4200A SCS rear panel connections for the methods mentioned in the Device connection schematic on page 7 2 topic You can make the connections shown in the followin...

Page 123: ...oltage sweep An I V curve is generated from the acquired data and device parameters are calculated in the Formulator For this example use the Clarius application to Create a new project Search for and...

Page 124: ...020 7 5 Search for and select a test To search for and select the test 1 Select Tests 2 In the Filters pane select Solar Cell Figure 109 Use filters to select the fwd ivsweep test 3 Select the Solar C...

Page 125: ...SMU 900 01 Rev A December 2020 Configure the test To configure the test 1 In the project tree select the fwd ivsweep solar cell I V test in the project tree 2 Select Configure Figure 111 Configure hig...

Page 126: ...U 900 01 Rev A December 2020 7 7 4 In the Test Settings pane adjust the Measure Settings and Test Mode as needed Figure 113 Test Settings pane The Formulator is also in the Test Settings pane If you s...

Page 127: ...device parameters See the Electrical Characterization of Photovoltaic Materials and Solar Cells with the 4200A SCS Parameter Analyzer application note for details on Formulator calculations You can al...

Page 128: ...0 7 9 Analyze the test results You can select Analyze when you run the project to view test results in real time Figure 116 Analyze highlighted You can also use the View icons in the upper right of th...

Page 129: ...sweep of an illuminated silicon photovoltaic PV cell generated by the SMU Figure 118 Test results showing I V graph of an illuminated solar cell Because the system SMUs can sink current the curve can...

Page 130: ...and trade names are the property of Keithley Instruments All other trademarks and trade names are the property of their respective companies Keithley Instruments Corporate Headquarters 28775 Aurora Ro...

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