Zoom in pin nest structure, test vehicle having the structure, and method of fabricating the structure

• US 20050122123A1
• Filed: 03/26/2003
• Published: 06/09/2005
• Est. Priority Date: 03/27/2002
• Status: Active Grant

• Current Assignee: PDF Solutions
• Original Assignee: PDF Solutions
• Inventors: Weiland, Larg H., Ciplickas, Deniis J., Hess, Christopher, Stine, Brian E.
• Granted Patent: US 7,154,115 B2
• Time in Patent Office: Days
• US Class Current: 324/719
• CPC Class Codes: H01L 22/34 Circuits for electrically characterising or monitoring manufacturing processes, e. g. whole test die, wafers filled with test structures, on-board-devices incorporated on each die, process control monitors or pad structures thereof, devices in scribe line switching, multiplexing, gating devices G01R19/25; process control with lithography, e.g. dose control, G03F7/20; structures for alignment control by optical means G03F7/70633

Abstract

A test vehicle (100) comprises a substrate (99), a plurality of nested serpentine lines (202) on the substrate, and a plurality of test pads (204) on the substrate. Each serpentine line has a plurality of turn sections that comprise two parallel line segments connected by a perpendicular line segment. Each of the plurality of test pads is connected to a respective turn section of a respective one of the nested serpentine lines. Each pair of test pads connected to one of the subset of the nested serpentine lines has at least a respectively different turn section portion connected therebetween.

Claims

1. A test vehicle, comprising

a substrate;

a plurality of nested serpentine conductive lines on the substrate, each serpentine line having a plurality of turn sections that comprise two parallel line segments connected by a perpendicular line segment; and

a plurality of test pads on the substrate, each connected to a respective portion of a respective one of the nested serpentine lines, such that each of a subset of the nested serpentine lines has at least three test pads, and each pair of consecutive test pads connected to one of the subset of the nested serpentine lines has a respectively different subset of the turn sections of that line connected therebetween.

2. The nest structure of claim 1, wherein a subset of the test pads are positioned externally to the nest structure, such that each of the subset of the test pads is connected between a respective pair of turn sections within the plurality of turn sections.

3. The nest structure of claim 2, wherein the nest structure includes a plurality of rows of test pads, each row having a respective test pad corresponding to each respective one of the plurality of lines, each row being connected at a respectively different intermediate location between ends of the plurality of nested serpentine lines, such that the test pads of any two consecutive rows of test pads are connected to a respectively different bunch of turn sections containing one or more turn sections of each of the nested serpentine lines.

4. The test vehicle of claim 3, wherein the test pads are further arranged in columns, and a pitch between pads within the rows is substantially the same as a pitch between pads within the columns.

5. The test vehicle of claim 2, wherein each of the subset of the nested serpentine lines includes a test pad in every fourth turn section of that nested serpentine line.

6. The nest structure of claim 1, wherein a subset of the test pads are positioned internally in the nest structure, with each of the subset of the test pads directly connected to a respective one of the turn sections.

7. The nest structure of claim 1, wherein at least one of the perpendicular line segments includes one or more comb segments positioned between the corresponding pad and the parallel line segments of that perpendicular line segment.

8. The nest structure of claim 1, wherein at least two consecutive turn sections of one or more of the nested serpentine lines have test pads directly connected thereto.

9. The test vehicle of claim 1, wherein the plurality of nested serpentine lines include between 12 and 23 lines.

10. The test vehicle of claim 1, wherein the test vehicle further comprises:

a second plurality of nested serpentine conductive lines on the same substrate as the first plurality of nested serpentine lines, each having a plurality of turn sections that comprise two parallel line segments connected by a perpendicular line segment, and

a second plurality of test pads on the same substrate, each connected to a respective portion of a respective one of the second plurality of nested serpentine lines, such that each of a subset of the second plurality of nested serpentine lines has at least three test pads, and any two consecutive pairs of the test pads connected to one of the subset of the second plurality of nested serpentine lines have a respectively different subset of the turn sections of that line connected therebetween; and

the first and second pluralities of nested serpentine lines and the first and second pluralities of test pads are optimized for one or more chip designs corresponding to one or more reticles.

11. The test vehicle of claim 10, wherein a single critical area is used for both the first and second plurality of nested serpentine lines.

12. A test vehicle, comprising

a substrate;

a plurality of nested serpentine conductive lines on the substrate, each serpentine line having a plurality of turn sections that comprise two parallel line segments connected by a perpendicular line segment; and

a plurality of test pads on the substrate, each connected to a respective turn section of a respective one of the nested serpentine lines, wherein a subset of the test pads are positioned internally in the nest structure.

13. The nest structure of claim 12, wherein each of the subset of test pads is located between the perpendicular lines segments of a respective adjacent pair of the perpendicular line segments.

14. The nest structure of claim 12, wherein at least one of the perpendicular line segments includes one or more comb segments positioned between the corresponding pad and the parallel line segments of that perpendicular line segment.

15. The nest structure of claim 12, wherein at least two consecutive turn sections of one or more of the nested serpentine lines have test pads directly connected thereto.

16. The test vehicle of claim 12, wherein each of the subset of the nested serpentine lines includes at least one test pad for every twenty turn sections.

17. A test vehicle, comprising

a substrate;

a plurality of nested serpentine conductive lines on the substrate, each serpentine line having a plurality of turn sections that comprise two parallel line segments connected by a perpendicular line segment; and

a plurality of test pads on the substrate, each connected to a respective portion of a respective one of the nested serpentine lines, such that each of a subset of the nested serpentine lines has at least three test pads, and each pair of test pads connected to one of the subset of the nested serpentine lines has at least a respectively different turn section portion connected therebetween.

18. The nest structure of claim 17, wherein a subset of the test pads are positioned internally in the nest structure.

19. The nest structure of claim 17, wherein each of the subset of test pads is located between the perpendicular lines segments of a respective adjacent pair of the perpendicular line segments.

20. The nest structure of claim 17, wherein at least one of the perpendicular line segments includes one or more comb segments positioned between the corresponding pad and the parallel line segments of that perpendicular line segment.

21. The nest structure of claim 17, wherein at least two consecutive turn sections of one or more of the nested serpentine lines have test pads directly connected thereto.

22. A method of testing, comprising the steps of:

(a) fabricating a test vehicle having a plurality of nested serpentine lines;

(b) probing fractional portions of individual ones of the nested serpentine lines for short circuits or open circuits; and

(c) identifying a fractional portion of at least one of the nested serpentine lines that contains a defect based on the probing.

23. The method of claim 22, wherein the probing step includes testing continuity between two pads, each pad abutting and continuous with a respective turn section of the same one of the lines, to test for an open circuit within a fractional portion of that line between the two pads.

24. The method of claim 22, wherein the probing step includes testing continuity between two pads, each pad abutting and continuous with a turn section of a respectively different one of the lines, to test for a short circuit connecting corresponding fractional portions of the two lines connected to the two pads.

25. The method of claim 22, wherein the probing step includes testing continuity between two pads positioned externally to the nested serpentine lines, each pad connected to a respective turn section of the same one of the lines, to test for an open circuit within a fractional portion of that line between the two pads.

26. The method of claim 22, wherein the probing step includes testing continuity between two pads positioned externally to the nested serpentine lines, each pad connected to a turn section of a respective one of the lines, to test for a short circuit connecting corresponding fractional portions of the two lines connected to the two pads.

27. The method of claim 22, wherein:

step (b) includes measuring voltage and current at four of the pads connected to corresponding fractional portions of two of the lines; and

step (c) includes determining a location of the defect within the fractional portions of the lines from the voltage and current measurements, based on a bridge calculation.

28. The method of claim 22, wherein step (b) includes rotating the test vehicle between probing for shorts and probing for opens.