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Patent US6013533A successfully refreshed from Google Patents.
US6013533A
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Real time quiescent current test limit methodology
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1997-09-05
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Granted: 2000-01-11
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Expires: 2017-09-05
Abstract
Abstract A method of sorting dies found on wafers is disclosed. Each wafer is part of a set of wafers and the sorting rejects some of the dies. The method first selects an acceptable deviation within an abstract distribution. A respective test parameter is measured and recorded for each die in the set of wafers, and a distribution of the test parameter across the set of wafers is calculated. Based on this distribution and the acceptable deviation, a test parameter limit is set and any dies having a test parameter value greater than the limit are rejected.
Inventors
- 👤 Emery Osamu Sugasawara
- 👤 Scott Franklin Keller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:30
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/30; G01R31/3004; G01R31/01; G01R31/282; G01R31/2831
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
127 words
A method of sorting dice, each die formed on a wafer, a plurality of wafers forming a wafer lot, the sorting rejecting some of the dice, the method comprising: selecting a first deviation in terms of standard deviations from a selected mean; measuring and recording a respective quiescent current drawn by each die in the wafer lot; calculating a measured statistical mean and a measured standard deviation of the quiescent currents for the dice in the wafer lot; setting a wafer lot specific quiescent current limit by multiplying the measured standard deviation by the first deviation to obtain a product and adding the product to the measured statistical mean; and rejecting the dice that have a quiescent current greater than the wafer lot specific quiescent current limit.
Claim 2
Independent Claim
127 words
A method of sorting dice, each die formed on a wafer, a plurality of wafers forming a wafer lot, the sorting rejecting some of the dice, the method comprising: selecting a first deviation in terms of standard deviations from a selected mean; measuring and recording a respective quiescent current drawn by each die in the wafer lot; calculating a measured statistical mean and a measured standard deviation of the quiescent currents for the dice in the wafer lot; setting a wafer lot specific quiescent current limit by multiplying the measured standard deviation by the first deviation to obtain a product and adding the product to the measured statistical mean; and rejecting the dice that have a quiescent current greater than the wafer lot specific quiescent current limit.
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein the measured statistical mean and the measured standard deviation are calculated based upon the quiescent current of all the dice in the wafer lot.
Claim 4
Dependent Claim
33 words
The method of claim 1 wherein the measured statistical mean and the measured standard deviation are calculated based upon the quiescent currents of fewer than all of the dice in the wafer lot.
Claim 5
Dependent Claim
50 words
The method of claim 1 wherein a first die in a first wafer lot has a first quiescent current that is less than the quiescent current limit for the first wafer lot but greater than the quiescent current limit for a second wafer lot, the first die not being rejected.
Claim 6
Dependent Claim
27 words
The method of claim 1 wherein the sorting is performed after the dice are formed on the wafer but before the dice are cut from the wafer.
Claim 7
Dependent Claim
17 words
The method of claim 1 wherein the sorting is performed after the dice are inserted in packages.
Claim 8
Independent Claim
136 words
A method of manufacturing dice, the method comprising: determining a first amount of variation between the dice in a wafer lot for a selected parameter; forming the dice on a wafer, a plurality of wafers forming the wafer lot, with each wafer in the wafer lot proximate to all other wafers in the wafer lot; measuring the selected parameter of the dice in the wafer lot to produce a plurality of measured test parameter values; calculating a distribution of the measured test parameter values for the wafer lot; setting a test parameter limit for the selected parameter based on the distribution of the measured test parameter values and the first amount of variation for the selected parameter; and designating the dice that have a test parameter value greater than the test parameter limit as rejected dice.
Claim 9
Independent Claim
136 words
A method of manufacturing dice, the method comprising: determining a first amount of variation between the dice in a wafer lot for a selected parameter; forming the dice on a wafer, a plurality of wafers forming the wafer lot, with each wafer in the wafer lot proximate to all other wafers in the wafer lot; measuring the selected parameter of the dice in the wafer lot to produce a plurality of measured test parameter values; calculating a distribution of the measured test parameter values for the wafer lot; setting a test parameter limit for the selected parameter based on the distribution of the measured test parameter values and the first amount of variation for the selected parameter; and designating the dice that have a test parameter value greater than the test parameter limit as rejected dice.
Claim 10
Dependent Claim
13 words
The method of claim 7 wherein the selected parameter is a quiescent current.
Claim 11
Dependent Claim
49 words
The method of claim 7 wherein the first amount of variation is set as a number of standard deviations from the selected mean, and the distribution is calculated as a statistical mean and the size of a standard deviation in terms of test parameter values from the statistical mean.
Claim 12
Dependent Claim
192 words
The method of claim 7 further comprising: determining a second amount of variation between the dice in the wafer lot for the selected parameter after determining the first amount of variation between the dice in the wafer lot for the selected parameter and before forming the dice on the wafers; cutting the wafers into individual cut die after designating the dice that have a test parameter value greater than the test parameter limit as rejected dice; discarding the rejected dice; packaging the dice that were not rejected, the packaging forming packaged dice; measuring the selected parameter in fewer than all of the packaged dice to produce a sampling of packaged test parameter values; calculating a packaged distribution of the packaged test parameter values from the sampling of packaged test parameter values; setting a packaged test parameter limit based on the packaged distribution of the packaged test parameter values and the second amount of variation between the dice; measuring the selected parameter of each of the packaged dice to produce final packaged test parameter values; and rejecting the packaged dice with final packaged test parameter values greater than the packaged test parameter limit.
Claim 13
Dependent Claim
13 words
The method of claim 10 wherein the selected parameter is a quiescent current.
Claim 14
Dependent Claim
19 words
The method of claim 10 wherein the first amount of variation is different from the second amount of variation.
Claim 15
Dependent Claim
52 words
The method of claim 10 wherein the second amount of variation is set as a number of standard deviations from a selected mean, and the packaged distribution is calculated as a statistical mean and the size of a standard deviation in terms of the packaged test parameter values from the statistical mean.
References Cited (Backward Citations)
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