Test ring oscillator
First Claim
1. A test apparatus for quantifying parasitics on a microprocessor, the test apparatus comprising:
- a plurality of first gate stages, said first gate stages having a first portion and a second portion;
a plurality of second gate stages, said second gate stages having a first portion and a second portion, said second gate stages connected in between said plurality of first gate stages, wherein said plurality of first gate stages and said plurality of second gate stages are connected together to form a ring oscillator, said ring oscillator producing a periodic signal;
a first signal path within said ring oscillator, said first signal path flowing through said first portion of said plurality of first gate stages and said first portion of said plurality of second gate stages;
a second signal path within said ring oscillator, said second signal path flowing through said second portion of said plurality of first gate stages and said second portion of said plurality of second gate stages;
a test node, connected between one of said plurality of first gate stages and one of said plurality of second gate stages, for monitoring said periodic signal produced by said ring oscillator;
wherein the high portion of said periodic signal produced by said ring oscillator at said test node flows through said first signal path, and the low portion of said periodic signal produced by said ring oscillator at said test node flows through said second signal path;
whereby the relationship of said high portion and said low portion of said periodic signal at said test node corresponds to the difference between said parasitics of said first signal path and said second signal path.
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Accused Products
Abstract
An apparatus and method for measuring parasitic differences between dissimilar conductive paths on a semiconductor is provided. The apparatus provides a ring oscillator which has two propagation paths. The first path is traversed on a logical transition from low to high, and the second path is traversed on a logical transition from high to low. The gate stages for the first path may be interconnected via a metal conductive layer, and the gate stages for the second path may be connected to a dissimilar metal, or polycide, for example. A single output signal is produced which has a period equal to twice the delay of the inverter stages, plus any delay associated with the parasitic difference in the two paths. The duty cycle of the periodic signal may then be used to determine the parasitic difference between the two materials used to interconnect the stages in the ring oscillator.
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Citations
39 Claims
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1. A test apparatus for quantifying parasitics on a microprocessor, the test apparatus comprising:
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a plurality of first gate stages, said first gate stages having a first portion and a second portion; a plurality of second gate stages, said second gate stages having a first portion and a second portion, said second gate stages connected in between said plurality of first gate stages, wherein said plurality of first gate stages and said plurality of second gate stages are connected together to form a ring oscillator, said ring oscillator producing a periodic signal; a first signal path within said ring oscillator, said first signal path flowing through said first portion of said plurality of first gate stages and said first portion of said plurality of second gate stages; a second signal path within said ring oscillator, said second signal path flowing through said second portion of said plurality of first gate stages and said second portion of said plurality of second gate stages; a test node, connected between one of said plurality of first gate stages and one of said plurality of second gate stages, for monitoring said periodic signal produced by said ring oscillator; wherein the high portion of said periodic signal produced by said ring oscillator at said test node flows through said first signal path, and the low portion of said periodic signal produced by said ring oscillator at said test node flows through said second signal path; whereby the relationship of said high portion and said low portion of said periodic signal at said test node corresponds to the difference between said parasitics of said first signal path and said second signal path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A semiconductor device, manufactured on a substrate, the semiconductor device having a plurality of transistors connected together with interconnection materials having dissimilar electrical parasitics, the semiconductor device having a plurality of test circuits, the test circuits providing indicia of the electrical parasitics of the interconnection materials, each of the test circuits comprising:
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a dual path ring oscillator, said ring oscillator comprising; a plurality of gate stages connected together to form a ring; a first path through said gate stages connected using a first interconnection material; and a second path through said gate stages connected using a second interconnection material; wherein said first path and said second path through said gate stages produces a periodic signal, said signal having a duty cycle corresponding to the electrical parasitic difference between said first interconnection material and said second interconnection material; and a test node, connected between two of said plurality of gate stages, for detecting said periodic signal. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for measuring parasitics on a semiconductor device, the semiconductor device having a dual path test circuit which produces a periodic signal, the method comprising the steps of:
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connecting a first interconnection material along a first path of the dual path test circuit; connecting a second interconnection material along a second path of the dual path test circuit; measuring the high portion of the periodic signal propagated through the first path; measuring the low portion of the periodic signal propagated through the second path; and comparing the measured high and low portions of the periodic signal to determine the parasitic difference between the first and second interconnection materials. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39)
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Specification