Interposer defect coverage metric and method to maximize the same

Patent metadata

Field	Value
Publication number	US-9514268-B2
Application number	US-201514868525-A
Country	US
Kind code	B2
Filing date	Sep 29, 2015
Priority date	Aug 21, 2013
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A method includes receiving a design of an interposer having nets, probe pads, and micro-bumps. The nets connect the micro-bumps. The probe pads are initially unconnected to the nets. The method further includes initializing a first set to logically include the nets; processing the first set such that every net interconnecting more than two micro-bumps is divided into a plurality of nets and every two micro-bumps are interconnected by one net; calculating an untested length for each net in the first set; selecting a net N from the first set wherein the net N has the maximum untested length in the first set, the net N representing at least a portion of a net P of the nets; selecting a pair of probe pads that are unconnected to the nets; and connecting the pair of probe pads to the net P by two dummy nets.

First claim

What is claimed is:

1. A method, comprising the steps of:
receiving a design of an interposer for a three-dimensional integrated circuit, the interposer having nets, probe pads, and micro-bumps, each of the nets connecting at least one of the micro-bumps, the probe pads initially unconnected to the nets;
initializing a first set to logically include the nets;
processing the first set such that every net interconnecting more than two micro-bumps is divided into a plurality of nets and every two of the more than two micro-bumps are interconnected by one of the plurality of nets;
calculating an untested length for each net in the first set;
selecting a net N from the first set wherein the net N has the maximum untested length among all nets in the first set, the net N representing at least a portion of a net P of the nets;
selecting a pair of probe pads from the probe pads that are unconnected to the nets; and
connecting the pair of probe pads to the net P by two dummy nets, wherein at least one of: the initializing of the first set, the processing of the first set, the calculating of the untested length, the selecting of the net N, the selecting of the pair of probe pads, and the connecting of the pair of probe pads is performed by a computing system.

2. The method of claim 1 , further comprising:
updating the first set such that, for each net M in the first set that has an overlapping portion with the net N, subtracting a length of the overlapping portion from the untested length of the net M.

3. The method of claim 2 , further comprising:
repeating the steps of selecting the net N, selecting the pair of probe pads, connecting the pair of probe pads, and updating the first set until one of two conditions (a) and (b) is met: (a) the maximum untested length of all nets in the first set is less than a pre-determined value, and (b) there is no pair of probe pads from the probe pads that are unconnected to the nets.

4. The method of claim 3 , wherein the initializing of the first set also initializes a first variable to zero and a second variable to a summation of a length of each of the nets, further comprising, before each of the repetitions of the steps:
updating the first variable to include the untested length of the net N; and
calculating a ratio between the first variable and the second variable.

5. The method of claim 3 , wherein the initializing of the first set also initializes a first variable to zero and a second variable to a summation of a length of each of the nets, further comprising, before each of the repetitions of the steps:
calculating a first length of the two dummy nets;
updating the first variable to include both the untested length of the net N and the first length;
updating the second variable to include the first length; and
calculating a ratio between the first variable and the second variable.

6. The method of claim 3 , wherein the initializing of the first set also initializes a first variable to zero and a second variable to a summation of a length of each of the nets, and wherein the two dummy nets join the net P at two joints, further comprising, before each of the repetitions of the steps:
calculating a first length of the two dummy nets;
calculating a second length of first and second portions of the net N, wherein the first portion is between one of the two joints and a micro-bump associated with the net N, the second portion is between another one of the two joints and another micro-bump associated with the net N, and the first and second portions are not tested by the pair of probe pads;
updating the first variable to include both the untested length of the net N and the first length, and to exclude the second length;
updating the second variable to include the first length; and
calculating a ratio between the first variable and the second variable.

7. The method of claim 1 , wherein the selecting the pair of probe pads is based on a cost function that considers at least: a routing congestion of the interposer, a length of dummy nets to be inserted for connecting the pair of probe pads to the net P, a timing constraint of the net P, or a combination thereof.

8. The method of claim 2 , further comprising:
removing the net N from the first set.

9. A method, comprising the steps of:
receiving a design of an interposer for a three-dimensional integrated circuit, the interposer having nets, probe pads, and micro-bumps, each of the nets connecting at least one micro-bump, and the probe pads initially unconnected to the nets;
initializing a first set and first and second variables, wherein the first set is initialized to logically include the nets, the first variable is initialized to zero, and the second variable is initialized to a summation of a length of each of the nets;
processing the first set such that every net interconnecting more than two micro-bumps is divided into a plurality of nets and every two of the more than two micro-bumps are interconnected by one of the plurality of nets;
calculating an untested length for each net in the first set;
selecting a net N from the first set wherein the net N has the maximum untested length among all nets in the first set, the net N representing at least a portion of a net P of the nets;
selecting a pair of probe pads from the probe pads that are unconnected to the nets;
connecting the pair of probe pads to the net P by two dummy nets; and
updating the first set such that, for each net M in the first set that has an overlapping portion with the net N, subtracting a length of the overlapping portion from the untested length of the net M,
wherein at least one of the steps of: initializing, processing, calculating, selecting the net N, selecting the pair of probe pads, connecting, and updating is performed by a computing system.

10. The method of claim 9 , further comprising:
repeating the steps of selecting the net N, selecting the pair of probe pads, connecting the pair of probe pads, and updating the first set until one of two conditions (a) and (b) is met: (a) the maximum untested length of all nets in the first set is less than a pre-determined value, and (b) there is no pair of probe pads from the probe pads that are unconnected to the nets.

11. The method of claim 10 , further comprising, before each of the repetitions of the steps:
updating the first variable to include the untested length of the net N; and
calculating a ratio between the first variable and the second variable.

12. The method of claim 10 , further comprising, before each of the repetitions of the steps:
calculating a first length of the two dummy nets;
updating the first variable to include both the untested length of the net N and the first length;
updating the second variable to include the first length; and
calculating a ratio between the first variable and the second variable.

13. The method of claim 10 , wherein the two dummy nets join the net P at two joints, further comprising, before each of the repetitions of the steps:
calculating a first length of the two dummy nets;
calculating a second length of first and second portions of the net N, wherein the first portion is between one of the two joints and a micro-bump associated with the net N, the second portion is between another one of the two joints and another micro-bump associated with the net N, and the first and second portions are not tested by the pair of probe pads;
updating the first variable to include both the untested length of the net N and the first length, and to exclude the second length;
updating the second variable to include the first length; and
calculating a ratio between t

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Goel Sandeep Kumar
• Mehta Ashok

Classifications

• H10W72/952

  comprising metals or metalloids, e.g. PbSn, Ag or Cu · CPC title

• H10W72/29

  Bond pads specially adapted therefor · CPC title

• H10W70/652

  Cross-sectional shapes · CPC title

• H10W70/655

  Fan-out layouts · CPC title

• H10W70/654

  Top-view layouts · CPC title