jandel four-point probe system with rm3 test unit standard

DOCUMENT:JANDEL RM3 Four-Point Probe System Version: 1.0

JANDEL Four-point Probe System with RM3

Test Unit Standard Operating Procedure

Version: 1.0 March 2013

UNIVERSITY OF TEXAS AT ARLINGTON

Nanotechnology Research & Education Center


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TABLE OF CONTENTS

1. Introduction…………………………………………….…………...2

1.1 Scope of Work…………………………………….…......2

1.2 Description…………………………………….…….……3

1.3 Safety……………………………………………....……..3

2. Hardware..............................……………………………….….....4

3. Requirements……………………………………..….….…….…..5

3.1 Training…………………………………….……..…...….5

3.2 System Restrictions………………………...……..…....5

4 Operating Procedures.………………………..…..…………......6

4.1 System Pre-Checks………………………….…...........6

4.2 Operating the Jandel Four Point Probe RM3 …….....7

5 Recipes…….………………………..…..……………….…..……11

5.1 Technical Information..................................................11

1.0 INTRODUCTION

1.1 Scope

These procedures apply to the Jandel Four-point Probe System with RM3 Test Unit. All maintenance should follow the procedures set forth in the manufacturer’s maintenance and operations manuals. This document is for reference only. Users must be trained by Nanofab staff before operating this equipment.


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1.2 Description

The Jandel Four-point Probe System with RM3 Test Unit is a combined constant current source and digital voltmeter. It has been designed for use in making resistivity measurements in combination with four point probe equipment. The unit supplies a constant current and displays either the resultant voltage or the sheet resistance of the

sample in ohms/square (/), depending which function has been chosen. Voltage and sheet resistance can be measured on samples ranging from 5mm X 5mm to 5 “ diameter wafers.

1.3 Safety

1.3.1 This machine is connected to HIGH VOLTAGE. Be very careful and remain aware of electrical hazards. If you encounter any electrical malfunctions, contact NanoFAB staff immediately

1.3.2 The probehead can easily be damaged; do not bump anything in to the probes.


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1.3.3 Users are not allowed to adjust or remove probehead. For any probehead contact issues call staff.

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1.3.4 Read any posted NanoFAB Engineering Change Notices (ECN) for any hardware, process or safety changes before running the tool.

2.0 HARDWARE

2.1 LCD Display 16 x 2 with user Numeric Keypad for entry of selected test

currents or programmed set currents by selecting several program buttons.

2.2 Voltage or Sheet Resistance can be measured by selecting appropriate buttons.

2.3 Forward and Reverse currents by selecting appropriate buttons.

2.4 Automatic internal DVM calibration and compliance voltage at power up to limit power dissipation to the sample under test.

2.5 Stage can accommodate 5mm X 5mm samples to 5” diameter wafers.

2.6 Probehead is material is made of Tungsten Carbide (WC) with 50um tip radius and probe spacing of 1mm.


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3.0 REQUIREMENTS

3.1 Training

All users must be trained and authorized on the Jandel RM3 Four-point Probe system to use this tool. Training is supplied by a Nanofab staff member please contact the tool owner to schedule training.

3.2 System Restrictions

3.2.1 Users are NOT allowed to adjust or remove probehead. For any probehead contact issues call staff.

3.2.2 The probehead can easily be damaged; do not bump anything in to the probes.

3.2.3 The material must be capable of being probed (Ge, Si, and metals) .If you are not sure ask staff about the material you want to probe.

3.2.4 Only measure clean dry samples. Native oxide will impede good ohmic contact.

3.2.5 If a sample has a layer it must be opposite conductivity type to the substrate in order to electrically insulate this layer from the substrate. The layer should also have uniform homogenous doping.

3.2.6 Very low resistivity materials such as metals with thickness from 100A to 1µm

require maximum current (10ma) to achieve readings on the voltage display.

3.2.7 High sheet resistance (/) materials can be measured using very low currents

( 1µA @ < 200 mV ). Sheet resistances up to 107 / can be measured.

3.2.8 For thin layers (< 1µm) avoid puncturing the layer by excessive needle loading or

rapid decent velocity of the probes.

3.2.9 This system requires a NanoFab Management System reservation before using. http://nanofabreservation.uta.edu/

http://nanofabreservation.uta.edu/


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4.0 OPERATING PROCEDURES

4.1. System Pre-Checks

4.1.1. Check to ensure the lever with red cap and the probehead is all the way up. (The probehead can easily be damaged; do not bump anything in to the probes)

4.1.2. If the Jandel RM3 sheet resistance meter is already ON the display will show: Jandel RM3 V1.3 Standby H

If the tool is ON as shown continue to the next section. (To recalibrate the unit you will need to power down and power up the unit)


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4.2. Operating Jandel Four-point Probe System with RM3 Test Unit

4.2.1. If you have not completed the System Pre-Checks in steps 4.1.1 – 4.1.2 then you must complete those before proceeding.

4.2.2. If the unit is OFF turn the Jandel RM3 ON. The power switch is behind this electronic unit, next to the power cable. After calibration, the display will show ‘Jandel RM3 V1.3 Standby H ’.

(To recalibrate the unit you will need to power down and power up the unit)

4.2.3. Press FWD or REV. It will show some current value on the first line and some

voltage value on the second line. Press / if you want to measure the sheet resistance instead of voltage. Selecting REV applies current in opposite direction to FWD.

(By pressing / button you can toggle between sheet resistance and voltage measurements)


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4.2.4. Check to ensure lever with red cap and the probehead is all the way up. Place your wafer or piece of it on the stage under the probehead. The probehead can easily be damaged; do not bump anything in to the probes.

Note: Samples close to the thickness of a typical silicon wafer 100 m to 1 mm

(1000m ) can only be measured. Most wafers and films approximate ‘ infinite sheets’, however if the thickness is > 5 x probe spacing (s) the semi-infinite solid formula is within 1%. When the wafer thickness exceeds 5/8 (62.5%) of the spacing between the probe needles ( s= 1mm) the measured sheet resistance would need more than 1% correction. If your sample’s thickness is not in this range contact staff.

FPP correction factors for thickness and samples diameter are listed in Section : 5.1 Calculation of resistivity The smallest piece that can be used is about 5 mm x 5 mm. The probe spacing is 1mm. Samples 5 mm x 5 mm or smaller will have edge effects. FPP correction factors for thickness and samples diameter are listed in Section : 5.1 Calculation of resistivity

Place your wafer or piece of it on the stage under the probehead.

4.2.5. Select the current appropriate for your sample. Higher currents are needed

for highly conductive samples. As a guide, use the highest possible current that gives a consistent reading. The preset currents are set to A = 10 mA, B =

1 mA, C = 10 A, and D = 10 nA, and they can be selected by pressing these buttons. Any other value can be selected by using the numeric keypad and pressing the unit buttons. Generally, current should not be selected higher than 10 mA to avoid excessive heating of the sample.

preset currents numeric keypad unit buttons


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4.2.6. Slowly lower the red lever down. Make sure the head fully sits on the sample and the micro switch on the right side clicks. Do not use excessive force. If the micro switch does not click, contact staff. If Out of Range or Contact Limit errors show up, lift the lever up, reduce the current, and lower the lever again. Make sure you do not move the wafer or the stage while the probe head is down, that will damage the probehead.

. Do not use excessive force or downward velocity

4.2.7. Record your voltage or sheet resistance measurement.

4.2.8. For the resistivity mapping on your wafer, the stage can be rotated or moved in or out while the probehead is up. However, there is no interlock, it is your job to make sure that the probehead is all the UP before moving the stage. The rotation can be accomplished by turning the pins under the stage. The stage stops in four positions, so up to four points can be measured for any radius. The radius can be selected by pulling the stage out by pulling on to two opposite pins under the stage. The stage stops in preset positions.

probehead is all the UP before moving the stage


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4.2.9. When done with measuring , make sure to lift the probehead all the way up by moving the lever up. Remove your wafer without bumping anything in to the probehead. Turn power OFF on the back of RM3.

Lift the probehead all the way up Turn power OFF on the back of RM3

4.2.10. Enter the required information in the logbook.


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5 Technical Information

5.1 Calculation of resistivity

5.1.1 For bulk resistivity for wafers and films where t ÷ s < 0.5 and where t is thickness in cm .

ρ = R sh x t

5.1.2 For wafer thicknesses that exceed 0.625 x probe spacing use the following FPP thickness correction factors.

FPP Correction Factors for Sample Thickness t

t/s C1(t/s)

0.3 1.0000

0.4 0.9995

0.5 0.9974

0.6 0.9919

0.7 0.9816

0.8 0.9662

0.9 0.9459

1.0 0.9215

1.2 0.8643

1.4 0.8026

1.6 0.7419

1.8 0.6852

2.0 0.6337

5.1.3 For small size sample geometries of the testing area use the following FPP

sample diameters correction factors

FPP Correction Factors for Sample Diameter d

d/s C2(d/s)

10 4.1712

20 4.4364

30 4.4892

40 4.5080

50 4.5167

60 4.5215

70 4.5244

80 4.5262

90 4.5275

100 4.5284

200 4.5314

º 4.5320


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5.1.4 References and links :

http://www.fourpointprobes.com/jannotes.html http://www.jandel.co.uk/info/faq.html

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http://www.fourpointprobes.com/jannotes.html

http://www.jandel.co.uk/info/faq.html

jandel four-point probe system with rm3 test unit standard

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