1、Curve Tracer Training MaterialPrepared by : M.GausalyaDesign/Device Engineer,Curve Tracer,Probe Station: Wafer chuck, Scope and needle arrangement,Curve Tracer,Introduction,Curve tracer is used to verify any failures such as leakage, breakdown or hFE.If a wafer fails for a parameter, confirmation ca
2、n be done to relate whether the failure is caused by electrical defects or due to in-genuine tester readings with the help of curve tracer.,Vacuum,Start,Stop,Joystick,Chuck,Wafer,Figure#1,Figure#2,Probe Station,Figure#3: Needles are touching the wafer,Curve Tracer,Emitter, Collector and Base Wires C
3、onnected to Curve Tracer,Screen,Switch,Probe Station,Voltage Controller,Current Controller,Figure#4: Display Function Key with Current and Voltage Controller,Figure#5: Step Generator-With Step Amplitude function -Number of Steps for hFE measurement,Figure 6: Adapter,Figure 7: Lighting Switch,Figure
4、8: Safety Interlock Switch,Figure 9: Wires from Probe Station,Figure 10:Cursor - Cursor function keys are used to move the cursor to top, bottom, left and right. There are two common types of cursors, Dot and Cross,Figure 11:Repeat & Single Key Function Repeat- Real Time Display, gives continuous di
5、splay of the characteristic curvesSingle-Freezes the Display Screen/Single Snap Shot,Figure 12: Configuration Key, Polarity Key, Variable Supplier and ,Max Power/Supplied Voltage Function Keys,Cursor Coordinate(-10V,-2mA),Current/Div set to 500uA/Div- Can be varied by using Current Controller Key,Vo
6、lt/Div set to 2V/Div-Can be varied by using Voltage Controller Key,Currently the location of Cursor is at -2mA on the screen,Currently the location of Cursor is at -10V on the screen,Beta Value generated by Step Amplitude of Step Generator,Figure 13: This figure shows the curve tracer screen,Configu
7、ration Keys,Notice that there is no EBO configuration key in the diagram above! To Measure EBO current/breakdown its is necessary to change the Collector Wires (from Probe Station) to Emitter Adapter and Emitter Wires (from Probe Station) to Collector Adapter,How to Measure IEBO and BVEBO?,Figure 14
8、: This figure shows the connection of wires,Polarity Function Key,Figure 15: This figure shows the polarity key function on curve tracer,How to START?,Before getting started, make sure that the emitter/base/collector wires from the Station is connected to the correct adapters in the curve tracer. Ra
9、ise the needles up so that they wont touch the chuck/wafer. Get the wafer map of the wafer which fails for particular test. This will help to place the needles at the failing/passing die/area of the wafer to verify a failure.,Golden Rules:,This training material is divided into two sections: i) Prob
10、e Station Handling for Connection btw wafer and the needle wiresii) Curve tracer Handling for various electrical parameters,Probe Station Handling,Probe Station Handling,Normally for ISMF transistor mask set design, the emitter pad is designed to be located at bottom left and base pad at the top rig
11、ht of the mask set, provided the major flat is facing upward.,Get the wafer map of the wafer that need to be inspected. *Refer to Dorothys training package on Failure Analysis Mode to learn on how to use wafer map.,E.g.:,Die Design,Wafer Map,Tips #1,Tips # 2,Screw #1,Screw #2,Screw #3,Curve Tracer H
12、andling fori. Diode 1. Leakage1.1 ICBO1.2 ICEO1.3 IEBO 2. Breakdown2.1 BVCBO2.2 BVCEO2.3 BVEBOii. Transistors1. Leakage1.1 ICBO1.2 ICEO1.3 IEBO 2. Breakdown2.1 BVCBO2.2 BVCEO2.3 BVEBO3. hFE,There are various types of Leakage tests available. Below are thesummary of common leakage tests and their con
13、figuration key,1. Leakage Measurement,Curve Tracing a Diode,1.1 ICBO Measurement,1. First get the probe data and summary of the lot from VFET program or do a search of the lot simply by keying in EFC of the lot in auto test folder. (For this purpose, refer to Error Free Code of the lot. E.g.: Refer
14、to Figure 16 in the next slide),Check for the LOWEST test yield for the device which is being tested. (Refer to example above) The lowest percentage shows the exact parameter the device is failing for.,Probe Header File (Data File),Probe Summary,Get the latest probe summary of the lot. (Use EFC),Lot
15、 EFC,Probed Time,Probe MS,Probe Data/Summary,Figure 16: This figure shows the VFET file which contains all the probe summary and data of lots that were probed.,Probe Header:,A,B,C,D,1,2,3,4,5,Description:,Continue,- Shows the Test # for each test being evaluated on the device (E.g.: Test#1,2,3,25),-
16、 Shows test type/ name of the each test which are called by the device (E.g.: VBCFP, ICBO),- Shows Biasing (Bias#1 and Bias#2) of each test (E.g.: Test#9-ICBO biased at VCB=110V),- Shows Min and Max value of each test. This includes Stat Values and the 48A Specs. (E.g.: Test#1-9- ICBO with Max Spec
17、of 100nA-48A Spec),1,4,5,2,3,Description:,2. Check for lowest test yield in the probe summary and identify the test # & their type. (Eg: T#19 IR3 with 99.8%),Test#19 shows IR3 which refers to Test 9 with Max spec of 100nA.,Test#9 shows ICBO with biasing of VCB=110V,48A Spec Test,Stat Test with Biasi
18、ng Condition,3. Refer to Probe Data and check for the same test#. (E.g.: As shown below),ICBO biased with Negative voltage, VCB=-50V means that the substrate is p-type for A41 Device,6. To determine substrate type, check for the probe data of the device and look for any ICBO test. Look for their Bia
19、sing condition. (Refer to next slide) If the biasing limit is in negative voltage that means that the substrate is p-type. If the biasing shows positive voltage, it means that the substrate is n-type.,Continue,7. Now we have all the information listed below which are required for curve tracing- Test
20、 Biasing and Their Spec- Substrate Type8. Next, we can start working on the curve tracer. 9. Since we want to measure leakage current, there are few settings which need to be set before curve tracing the die.,Do Not TOUCH the wires or needles when safety interlock switch is ON!,Figure 20-Shows that
21、Only one needle is used to test single diode. The 2nd needle is facing up, making no contact on the wafer.,1.2 ICEO Measurement,Follow Step# 1 to 9.3 from Slide#23 to 30 .For Step 9.4, Set the configuration function key to measure CEO so that ICEO can be measured.Continue from Step # 9.5 to 11 (Slid
22、e#30 to 31) . ICEO can be measured by this method.,ICEO Leakage measurement is the same as ICBO except that the configuration key need to change to CEO.,1.3 IEBO Measurement,To Measure EBO current/breakdown its is necessary to change the Collector Wires (from Probe Station) to Emitter Adapter and Em
23、itter Wires (from Probe Station) to Collector Adapter Set the configuration key to CBO.,IEBO measurement is the same as the other measurements (ICBO,ICEO) except the configuration key.,Note: Follow the same steps as the ICBO measurement except swap the emitter and collector wires to each other adapt
24、er. (Slide 23 to 31),There are various types of breakdown tests available. Below are thesummary of common breakdown tests and their configuration & polarity keys,2. Breakdown Measurement for Diode,A Breakdown voltage is at which breakdown occurs and current increases uncontrollably,2.1 BVCBO Measure
25、ment,First get the probe data and summary of the lot from VFET program or do a search of the lot simply by keying in EFC of the lot in auto test folder. (For this purpose, refer to Error Free Code of the lot.),Probe Data:,Do Not TOUCH the wires or needles when safety interlock switch is ON!,Figure 2
26、1 -Breakdown curve.The device being tested in this example is a Diode with n-Type epi. Polarity will be set to ve full-wave rectified sine wave.Configuration set to CBOMax Volt Peak set to 400VCurrent/Div set to 2mA and Volt/Div is set to 20V/Div.This device breaks down at 2mA with volt of 123.6V(Go
27、od Die)When the breakdown occurs the current increases drastically,Cursor Coordinate is at (123.6V, 2.12mA),2.2 BVCEO Measurement,Follow Step# 1 to 9.2 from Slide#36 to 39 .For Step 9.3, Set the configuration function key to measure CEO so that ICEO can be measured.Continue from Step # 9.4 to 11 Sli
28、de# 40 to 41. BVCEO can be measured by this method.,BVCEO breakdown measurement is the same as BVCBO except that the configuration key need to change to CEO.,2.3 BVEBO Measurement,To Measure EBO breakdown,Change the Collector Wires (from Probe Station) to Emitter Adapter and Emitter Wires (from Prob
29、e Station) to Collector Adapter Set the configuration key to CBO.,BVEBO measurement is the same as the other measurements (BVCBO,BVCEO) except the configuration key.,Note: Follow Step# 1 to 11 from Slide#37 to 41 ( same as the BVCBO measurement except swap the emitter and collector wires to each oth
30、er adapter),Curve Tracing a Transistor and BRT,Normally for ISMF transistor mask set design, the emitter pad is designed to be located at bottom left and base pad at the top right of the mask set, provided the major flat is facing upward.,E.g.:,Die Design,There are two types of transistors, NPN and
31、PNP. NPN and NBRT transistors has N-type substrate PNP and PBRT transistors has P-type substrate,As mentioned earlier in the tips, remember that below are the needle configuration for transistors in ISMF.,Leakage Measurement for any transistor or BRTs are the same as the diode. Refer to Slide# 22-34
32、 for ICBO, ICEO and IEBO leakage measurement using Curve Tracer.,1. Leakage Measurement,The table above shows the summary of common leakage tests and their configuration keys.,1.1 BVCBO Measurement,First get the probe data and summary of the lot from VFET program or do a search of the lot simply by
33、keying in EFC of the lot in auto test folder. (For this purpose, refer to Error Free Code of the lot.),Check for the LOWEST test yield for the device which is being tested. (Refer to example above) The lowest percentage shows the exact parameter the device is failing for.,2. Check for lowest test yi
34、eld in the probe summary and identify the test # & their type. (Eg: T#20 BVCBO with 8.3%),3. Refer to Probe Data and check for the same test#. (E.g.: As shown below),Example:,7. Now we have all the information listed below which are required for curve tracing- Test Biasing and Their Spec- Substrate
35、Type8. Next, we can start working on the curve tracer. 9. Since we want to measure breakdown voltage, there are few settings which need to be set before curve tracing the die.,Figure 23: Collector SupplyThis function key is divided into twoi) Low- Applies for all low voltage application devices(400V
36、)ii) High-Applies for all high voltage devices such as PHIV/NHIV (2000V),Figure 22-Breakdown curve.The device being tested in this example is PNP type, which means that the epi is p-type. So the polarity will be set to ve full-wave rectified sine wave.Configuration set to CBOMax Volt Peak set to 400
37、VThis device breaks down at 1mA with volt of 121.6V(Good Die)When the breakdown occurs the current increases drastically,2.2 BVCEO Measurement,BVCEO breakdown measurement is the same as BVCBO except that the configuration key need to change to CEO.,1.3 BVEBO Measurement,To Measure EBO breakdown,Chan
38、ge the Collector Wires (from Probe Station) to Emitter Adapter and Emitter Wires (from Probe Station) to Collector Adapter Set the configuration key to CBO.,BVEBO measurement is the same as the other measurements (BVCBO,BVCEO) except the configuration key.,3. hFE Measurement,Normally a device might
39、fail for Low or High Hfe. These failures may not be genuine at times since it can be caused by improper probing or etc. Thus it is necessary to measure hfe through curve tracer to verify. Below are the steps to follow during hFE measurement using curve tracer.,HFE is the current gain, ration of IC/I
40、B where IC is Collector Current and IB is Base Current.,Continue,Figure 23: A typical hFE curve displayed by Transistor,Base Current per Step,IB1,If the Collector Current, IC=2mA and the targeted hFE is 200, the IB can be measured using IB=IC/hFE formula. So the base current, IB should be around 10uA so that the targeted hFE of 200 can be achieved.,IB per step,Continue,Figure 23: Typical hFE curve used as example,Thank You,
