Sensitive technique for metal-void detection
AssigneeAdvanced Micro Devices, Inc.
InventorsAmit P. Marathe, Nguyen D. Bui, Van Pham
Life of this patent
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Abstract
A categorization of a particular semiconductor wafer based on void size is obtained from sigma data and T0.1% failure data that has been obtained from wafers subjected to isothermal testing. The sigma data and the T0.1% failure data for the particular wafer is compared to stored data corresponding to ranges for sigma and T0.1% data for each of a plurality of void categories, and the particular wafer is categorized based on the stored data. The T0.1% failure data is computed based on a T50% failure data and the sigma value, so that small sample sizes can be utilized to obtain the stored data.
Claims18
A method for determining a void size of a semiconductor wafer, the method comprising the steps of:
- a) obtaining test data for a plurality of semiconductor wafers, the test data corresponding to time-to-fail for the semiconductor wafers;
- b) categorizing the plurality of semiconductor wafers into a plurality of categories based on sizes of voids formed in the semiconductor wafers;
- c) from the test data obtained in the step a), determining a time when a certain percentage of the wafers have failed;
- d) from the test data obtained in the step a), determining a sigma value for the test data;
- e) from the time obtained in the step c) and the sigma value obtained in the step d), deriving a time when x percent of the wafers have failed, x being a number less than or equal to one;
- and
- f) categorizing the semiconductor wafer based on the sigma value obtained in the step d) and the time derived in the step e).
A method for categorizing a particular semiconductor wafer based on void size, the method comprising the steps of:
- a) subjecting a plurality of semiconductor wafers to isothermal testing, the plurality of semiconductor wafers not including the particular semiconductor wafer;
- b) obtaining time-to-fail data and sigma data for the plurality of semiconductor wafers subjected to the isothermal testing, the time-to-fail data being obtained for at least a certain percentage of the wafers having failed;
- c) from the time-to-fail data and the sigma data obtained in the step b), computing a time when x percent of the wafers have failed, x being a number less than or equal to one;
- d) examining each of the plurality of semiconductor wafers under a microscope and categorizing each of the plurality of wafers based on sizes of voids formed in each of the plurality of semiconductor wafers;
- e) determining a range of values for the time-to-fail data and the sigma data for each of the categories in the step d);
- f) subjecting the particular semiconductor wafer to isothermal testing;
- g) obtaining time-to-fail data and sigma data for the particular semiconductor wafer subjected to the isothermal testing;
- and
- h) categorizing the particular semiconductor wafer into a catergory based on the sigma data and the time-to-fail data obtained in the step g), and the range of values for the time-to-fail data and the sigma data obtained in the step e).
A method of categorizing a wafer based on void size, the method comprising the steps of:
- a) subjecting the wafer to isothermal testing, the wafer being subjected to the isothermal testing along with a set of other wafers;
- b) obtaining time-to-fail data and sigma data for the wafer, based on data obtained from the isothermal testing in the step a);
- c) comparing the time-to-fail data and the sigma data for the wafer against stored ranges of time-to-fail data and stored ranges of sigma data for a plurality of void categories;
- and
- d) determining one of the void categories for the wafer based on the comparing performed in the step c).
Dependencies are inferred from the claim text.