Enhanced grading and sorting of semiconductor devices using modular “plug-in” sort algorithms

• US 6,747,228 B2
• Filed: 01/22/2002
• Issued: 06/08/2004
• Est. Priority Date: 03/30/1999
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Capser, Lance M.
• Primary Examiner(s): Walsh, Donald P.
• Assistant Examiner(s): RODRIGUEZ, JOSEPH C
• Application Number:
  US10/054,430
• Publication Number:
  US 20020063085A1
• Time in Patent Office: 868 Days
• Field of Search: 209/571, 209/573, 324/759, 324/765, 324/158.1
• US Class Current: 209/571
• CPC Class Codes: G11C 29/54 Arrangements for designing test circuits, e.g. design for test [DFT] tools
• CPC Class Codes: G11C 29/56 External testing equipment for static stores, e.g. automatic test equipment [ATE]; Interfaces therefor

Abstract

A semiconductor device sorting method and apparatus involve development of small, self-contained and focused “qualification” or “sort” algorithm test programs or “modules”, each of which modules may test for the validity of a particular, selected grade of a memory or other semiconductor device based on the results of a test pattern associated with, or exhibited by, a particular device under test. Separating the test code from the main flow file of the test program into the aforementioned “plug-in” qualification or sort modules permits the test code to be much simpler and facilitates better organization, as each qualification or sort module may be independent of any other qualification or sort module and only determines in response to its associated test pattern whether or not (TRUE or FALSE) a device qualifies in a given device grade.

Claims

1. A method of qualifying and sorting semiconductor devices, comprising:

grouping a plurality of semiconductor devices into a test lot;

selecting a plurality of device grades and a downgrade path for each selected device grade;

selecting a test sequence including a plurality of tests, each test corresponding to at least one device grade of the plurality of device grades;

defining an initial selected device grade as a current device grade of the plurality of device grades for the test lot;

sorting each semiconductor device in the test lot to a final device grade of the plurality of device grades, the sorting comprising;

executing at least one test of the test sequence corresponding to the current device grade of each of the plurality of semiconductor devices; and

after each test executed, sequentially sorting each semiconductor device through the plurality of selected device grades along a selected downgrade path and assigning another device grade as the current device grade and reexecuting at least another test until the current device grade is the final device grade or the semiconductor device fails each of the plurality of device grades; and

separating the plurality of semiconductor devices from the test lot according to the final device grade of each semiconductor device.

2. The method of claim 1, further comprising sequentially sorting only those semiconductor devices through the plurality of selected device grades that fail a test which is not constrained to the device grade corresponding to the failed test.

3. A method of qualifying and sorting semiconductor devices, comprising:

selecting a plurality of device grades and a downgrade path for each selected device grade;

selecting a first test to be performed on at least one semiconductor device;

executing the first test on the at least one semiconductor device to cause the at least one semiconductor device to exhibit a test pattern responsive thereto; and

sequentially sorting the at least one semiconductor device through at least two of the plurality of selected device grades along at least one downgrade path responsive to the exhibited test pattern by sequentially comparing the exhibited test pattern to a discrete set of criteria relating to the first test for each of the at least two selected device grades and assigning another device grade and reexecuting a second test until one of the plurality of selected device grades is a final device grade or the semiconductor device fails each of the plurality of selected device grades.

4. A method of qualifying and sorting semiconductor devices, comprising:

selecting a plurality of device grades and a downgrade path for each selected device grade; and

sequentially sorting at least one semiconductor device through the plurality of selected device grades along a selected downgrade path solely according to a result of a first test pattern exhibited by the at least one semiconductor device responsive to a first test associated with a first test register selected by a test program and assigning another one of the plurality of device grades and reexecuting a second test until one of the plurality of selected device grades is a final device grade or the at least one semiconductor device fails each of the plurality of selected device grades.

5. The method of claim 4, further comprising:

sequentially sorting the at least one semiconductor device through the plurality of selected device grades along the selected downgrade path solely according to a result of a second test pattern exhibited by the at least one semiconductor device responsive to a second, different test associated with a second test register selected by the test program.

6. A method of qualifying and sorting a semiconductor device, comprising:

defining a plurality of device grades, a downgrade path between the plurality of device grades and an initial device trade as a current device grade of the semiconductor device from among the plurality of device grades;

testing the semiconductor device with at least one test from a plurality of tests corresponding to the current device grade; and

when the semiconductor device fails the at least one test, retesting the semiconductor device at the current device grade reassigned from another one of the plurality of device grades along the downgrade path until either the semiconductor device remains at a final device grade from among the plurality of device grades or the semiconductor device fails all of the plurality of device grades.