Method and apparatus for massively parallel multi-wafer test
View Patent ↗Disclosed herein is a cost effective, efficient, massively parallel multi-wafer test cell. Additionally, this test cell can be used for both single-touchdown and multiple-touchdown applications. The invention uses a novel “split-cartridge” design, combined with a method for aligning wafers when they are separated from the probe card assembly, to create a cost effective, efficient multi-wafer test cell. A “probe-card stops” design may be used within the cartridge to simplify the overall cartridge design and operation.
1. A system comprising:
a cartridge rack including a plurality of slots;
a plurality of cartridge top sections, wherein each cartridge top section is docked in a respective slot of said cartridge rack;
a plurality of probe cards, wherein each probe card is mounted to a respective cartridge top section;
a plurality of cartridge bottom sections; and
a wafer cartridge handler,
to determine, before production testing, a first set of alignment constants for each pair of cartridge bottom sections and cartridge top sections, and a second set of alignment constants for each probe card and respective cartridge top section,
to load, during production testing, each of a plurality of wafers into a given cartridge bottom section,
to align, during production testing, each wafer in said respective given cartridge bottom section based upon said first set of alignment constants and said second set of alignment constants for the respective cartridge bottom section paired to a particular cartridge top section and respective probe card; and
to move, during production testing, said respective cartridge bottom section with loaded and aligned wafer to said cartridge rack and mate said respective cartridge bottom section to said particular paired cartridge top section, wherein mechanical alignment features on said cartridge top section mates with mechanical alignment features on said cartridge bottom section.
2. The system of claim 1 , configured to support multiple touchdown testing, wherein a separate target slot in said cartridge rack is dedicated to each touchdown.
3. The test cell of claim 1 , wherein said wafer cartridge handler is configured to accept one or more Front Opening Unified Pods (FOUPS) containing said wafers which are loaded into said cartridge bottom sections.
4. The system of claim 1 , including:
automated test equipment; and
a backplane acting as an interface between said automated test equipment and said cartridge top sections.
5. The system of claim 4 , wherein said automated test equipment is a set of computer-controlled electronic hardware which provides stimuli to devices on said wafers and measures and records results.
6. The system of claim 4 , wherein said wafer cartridge handler includes:
load ports into which a front opening unified pod (FOUP) is inserted;
robotics configured to remove a wafer from said FOUP and mount it on a given cartridge bottom section for alignment; said cartridge rack an alignment station where alignment of said each wafer in said respective cartridge bottom section occurs.
7. The system of claim 6 , wherein said alignment station is configured to utilize optical alignment.
8. The system of claim 6 , wherein said alignment station is configured to utilize mechanical alignment.
9. The system of claim 1 , configured to enable testing of at least one of said plurality of wafers while at least one other of said plurality of wafers is being aligned.
10. The system of claim 1 , wherein said probe cards include rigid stops distributed approximately evenly throughout said probe card, said rigid stops designed to accurately control z-travel required to vertically position the probe card and wafer such that probes on said probe card are properly contacting pads on the wafer.
11. The system of claim 10 , wherein said rigid stops are fabricated to a height that allows said probes to contact said pads and to compress a user-determined amount before said rigid stops contact said wafer and prevent further compression.
12. The system of claim 11 , wherein said rigid stops are arranged in a two dimensional array pattern.
13. The system of claim 11 , wherein said rigid stops are arranged in a pattern of lines in the X or Y axis.