Overview

This learning activity will give you a peek into the manufacturing process for integrated circuits. Integrated circuits are made on semiconductor wafers and each wafer must pass through a series of steps before the circuits are operational. Often there are hundreds of steps required and these steps can seem very cyclical. For instance a wafer can go through many separate photolithography steps in order to create a new layer of microscopic features. In this activity you will imagine a set of five procedures a group of wafers must pass through, which in reality would represent only a small fraction of the entire manufacturing process. As the engineer in charge of this particular portion of the process, you will choose how many machines to devote to each of the five procedures. Your goal is to move a set of 100 wafers through the steps in the least amount of time. Each step takes a different amount of time and pieces of equipment cost different amounts of money. Since you have a limited budget, you’ll have to allocate your resources wisely!

Help

Setting up your manufacturing line and starting a process
Your batch of wafers must go through five steps. These steps are indicated by the blue boxes near the top of the screen. The machines required to complete each of these steps can be purchased by clicking on the green buttons below the blue boxes. In order to start your batch of 100 wafers moving through your process, you must purchase at least one of each type of machine. Once these machines have been purchased, the Run Process button at the top of the page will blink. This blinking indicates that you can press the button and start moving the wafers through your process.

Buying and selling equipment
You have a total of $10,000,000 to spend on equipment and you can choose to allocate it any way you would like, as long as you purchase at least one of each type of machine. When you make a purchase, that machine’s cost will be deducted from your account balance. You can purchase up to five of any type ofmachine by continually pressing the Buy button. Once you have five units of a type of machine, pressing that machine’s green Buy button will not produce any changes. You can purchase machines at any time, even while a process is running, as long as you have the necessary amount of money in your account. Once you have purchased a machine you can also choose to sell it for the full amount of its purchase price by pressing the red Sell button. Selling a machine cannot take place while a process is running.

Stopping a process
Once a process run has started, you can stop it before it reaches completion by clicking the Stop Process button near the top of the screen. This button appears only after a process has been started. Stopping a process will be like starting over and all 100 wafers will be pushed back to their original starting position.

Wafer queues
Wafer queues indicate the number of wafers waiting for a particular step. Once a wafer has entered a step, the machine used for that step will blink and the number of wafers in the queue will drop by one. If many wafers are building up in a queue during the process, that is a good indicator that more machines should be purchased for that step if money is available.Minimizing process timeYour ultimate goal should be to minimize the total time to move all 100 wafers through your process. This time is kept in the upper right hand corner of the screen. Allocate your machine purchases so that wafers move through as quickly as possible. An optimal solution will not be obvious. You will likely need to try several configurations to ensure you’ve made the best purchasing decisions. Good designs should take less than 2:50.

Questions

Be prepared to answer the following questions in relation to this learning activity:

1)What was the least amount of time needed for 100 wafers to complete the process?

2)How many Steppers did you use in your best equipment configuration?

3)How many Chemical Etchers did you use in your best equipment configuration?