Getting Parts for Your Project :: ECE 445 - Senior Design Laboratory

Getting Parts for Your Project

Student groups have a budget of $50 per student as of fall 2023. This money can be accessed through your TAs CFOP number. The ways parts can be sources are listed below in order of desirability.

1. Lab Kit

Each group is issued a locker and lab kit. A lab kit should include banana plugs and a breadboard.

2. ECEB 2070 Lab

There are many parts available for free in the ECEB 2070 lab such as THT passive components, MOSFETs, and line operated DC power supplies.

3. ECE 445 Inventory

Your TA can check out parts ECE 445 stores in white cabinets at the back of the lab: link. This inventory spreadsheet has not been updated in some time. There are items on this list that may not be in the cabinets and there are items in the cabinets that may not be on this list. Use this form for checkout: link

4. Electronics Services Shop (A.K.A. ECE Services Shop)

The Electronics Services Shop is located on the first floor of ECEB near the cargo elevator in ECEB 1041. They have a large stock of THT ICs (such as op-amps), potentiometers, motors, resistors, connectors, etc. Visit them when they are open to pick up parts.

Self-Service Inventory

Recently, they have started stocking 0805 surface mount passive components, crystal oscillators, microcontrollers, and linear regulators. The microcontroller portion of your board can probably be built entirely with parts from the Electronics Services Shop.  You do not need to pay for parts you obtain from the Electronics Services Shop.

E-shop website

To obtain SMD parts from the E-Shop, please use the Excel form sent out by your TA. Fill out the form and email it to your TA, who will place the order with the E-Shop and pickup it up. Your TA will receive an email when the parts are ready and will bring them to your group in the lab. Your TA must pickup the parts from the E-Shop; the E-Shop will not release parts to you directly.

SMD Parts Request Form link

 

5. ECE Supply Center (A.K.A. ECE Store)

The ECE Supply Center is located on the first floor of ECEB in room 1031 near the loading dock. You must pay for parts out of pocket or with your TA's CFOP number. They stock breadboards, project boxes, jumper wires, THT LSI logic ICs, THT analog ICs, and more. This is a fantastic resource for building prototypes. You can search their catalog here: https://my.ece.illinois.edu/storeroom/catalog.asp.

6. Free Samples from Companies

It should be mentioned that companies many times are willing to provide small quantities of their products to students engaged in design projects. You might consider approaching the manufacturer directly, particularly regarding their newer products which they are interested in promoting. Don't count on success with this, but it has often been very useful.

7. MY.ECE Ordering (last resort)

You can order parts from amazon, digikey, mouser, etc. using the money provided to you by the course with your TA's CFOP number. Orders placed through this avenue must be approved by your TA through myECE. If you order multiple parts through digikey or mouser, please provide a shopping cart link. This method of ordering is best for parts that cannot be found in any of the sources listed above. This includes SMD MOSFETs, high performance ADCs/DACs, power converter ICs, SMD op amps, modem ICs, etc. Please refer to this tutorial for more instructions: http://courses.engr.illinois.edu/ece445/lab/resources/ece_purchasing_app_tutorial.pdf

Personal Purchases

It is always possible and encouraged to purchase your own parts from a local store (Radio Shack, Best Buy, etc.) or order them from online vendors. Personal purchases will not be reimbursed by the department.

Four Point Probe

Simon Danthinne, Ming-Yan Hsiao, Dorian Tricaud

Four Point Probe

Featured Project

# Four Point Probe

Team Members:

Simon Danthinne(simoned2)

Ming-Yan Hsiao(myhsiao2)

Dorian Tricaud (tricaud2)

# Problem:

In the manufacturing process of semiconductor wafers, numerous pieces of test equipment are essential to verify that each manufacturing step has been correctly executed. This requirement significantly raises the cost barrier for entering semiconductor manufacturing, making it challenging for students and hobbyists to gain practical experience. To address this issue, we propose developing an all-in-one four-point probe setup. This device will enable users to measure the surface resistivity of a wafer, a critical parameter that can provide insights into various properties of the wafer, such as its doping level. By offering a more accessible and cost-effective solution, we aim to lower the entry barriers and facilitate hands-on learning and experimentation in semiconductor manufacturing.

# Solution:

Our design will use an off-the-shelf four point probe head for the precision manufacturing tolerances which will be used for contact with the wafer. This wafer contact solution will then be connected to a current source precisely controlled by an IC as well as an ADC to measure the voltage. For user interface, we will have an array of buttons for user input as well as an LCD screen to provide measurement readout and parameter setup regarding wafer information. This will allow us to make better approximations for the wafer based on size and doping type.

# Solution Components:

## Subsystem 1: Measurement system

We will utilize a four-point probe head (HPS2523) with 2mm diameter gold tips to measure the sheet resistance of the silicon wafer. A DC voltage regulator (DIO6905CSH3) will be employed to force current through the two outer tips, while a 24-bit ADC (MCP3561RT-E/ST) will measure the voltage across the two inner tips, with expected measurements in the millivolt range and current operation lasting several milliseconds. Additionally, we plan to use an AC voltage regulator (TPS79633QDCQRQ1) to transiently sweep the outer tips to measure capacitances between them, which will help determine the dopants present. To accurately measure the low voltages, we will amplify the signal using an JFET op-amp (OPA140AIDGKR) to ensure it falls within the ADC’s specifications. Using these measurements, we can apply formulas with corrections for real-world factors to calculate the sheet resistance and other parameters of the wafer.

## Subsystem 2: User Input

To enable users to interact effectively with the measurement system, we will implement an array of buttons that offer various functions such as calibration, measurement setup, and measurement polling. This interface will let users configure the measurement system to ensure that the approximations are suitable for the specific properties of the wafer. The button interface will provide users with the ability to initiate calibration routines to ensure accuracy and reliability, and set up measurements by defining parameters like type, range, and size tailored to the wafer’s characteristics. Additionally, users can poll measurements to start, stop, and monitor ongoing measurements, allowing for real-time adjustments and data collection. The interface also allows users to make approximations regarding other wafer properties so the user can quickly find out more information on their wafer. This comprehensive button interface will make the measurement system user-friendly and adaptable, ensuring precise and efficient measurements tailored to the specific needs of each wafer.

## Subsystem 3: Display

To provide output to users, we will utilize a monochrome 2.4 inch 128x64 OLED LCD display driven over SPI from the MCU. This display will not only present data clearly but also serve as an interface for users to interact with the device. The monochrome LCD will be instrumental in displaying measurement results, system status, and other relevant information in a straightforward and easy-to-read format. Additionally, it will facilitate user interaction by providing visual feedback during calibration, measurement setup, and polling processes. This ensures that users can efficiently navigate and operate the device, making the overall experience intuitive and user-friendly.

# Criterion for Success:

A precise constant current can be run through the wafer for various samples

Measurement system can identify voltage (10mV range minimum) across wafer

Measurement data and calculations can be viewed on LCD

Button inputs allow us to navigate and setup measurement parameters

Total part cost per unit must be less than cheapest readily available four point probes (≤ 650 USD)

Project Videos

Business Office

If none of these methods work, you can go through the business office with the help of your TA.