21 Control 10

21 Control 10 - Process Control This lecture covers how we...

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Note: The format of this lecture is similar to the oxidation lecture! Some slides have questions which you must answer and submit as a “work file” for the lecture (in place of a quiz). Work file questions appear in YELLOW BOXES Process Control This lecture covers how we control the outcome of processing… Note: Many questions are open-ended. The answers are less important than the personal review process you use to
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Process control The topics for this module are: 1. Goals for process control 2. Data collection 3. Statistical descriptions 4. Presentation and decision making
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Why control? If the process were carried out as intended, there would be no need for a special control regime or any validation. Unfortunately, Every process that we have discussed has several variables e.g. Oxidation: Temperature Gas flow Surface cleanliness Trace impurities in gas Wafer position in tube etc These should be the same for every wafer in every lot but there are small random variations
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Control what? In this cross-section, identify 10 properties that could vary during processing. 1 2 3 4 5 6 7 8 9 10 Please complete this table for your own file slides, then cut and paste it to the Word work-file for submission.
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Gross effects of process variation 1. Microprocessor example Number of ICs produced Max clock frequency (GHz) Economy line Standard Performance Premium Performance is reflected in the price that can be charged but they all have the same manufacturing cost Wouldn’t it be good to be able to skew the distribution ?
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Gross effects of process variation 2. Custom part Number of ICs produced Max clock frequency (or power, or standby current, or …) Not acceptable = fail Our sales team have been so enthusiastic to get the order, they promised rather more than our process could deliver. Only this part of the distribution is acceptable to the customer. Since it is a unique spec, the other parts have no market and so generate no revenue. Wouldn’t it be good to be able to skew the distribution ?
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Impact on product Impact on other process steps Local effects of process variation Process step Proceed to next process step ? Select 3 process steps that we have covered. Complete the table below to show what you think would be the major factor to determine if the outcome was good enough to proceed Unit process The most important criterion for a ‘pass’ result 1 2 3
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Data collection Data is collected from many sources: Unit process Log of incoming wafer history Product and test device performance measured at end of completed process Information from test structures (not transistors) on product wafers Information from test wafers Information from process equipment and people Deal with these 2 in this topic
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Size of a fab database It is very easy to collect a lot of data from fab equipment and from test structures. How much data could be collected in a
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This note was uploaded on 05/11/2010 for the course EEE EEE-530 taught by Professor Kozicki during the Spring '10 term at ASU.

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21 Control 10 - Process Control This lecture covers how we...

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