US5410490A — Electromigration verification method and apparatus

Claim 1

Independent Claim 109 words

A computer-implemented method for use in making an integrated circuit, comprising the steps of: a) analyzing predefined artwork data associated with the circuit to determine a capacitance of a net of the circuit; b) determining a frequency associated with said net; c) determining a voltage swing associated with said net; d) computing a current on the basis of at least said capacitance, frequency and voltage swing; e) computing a minimum allowable width for said net on the basis of at least said current; and f) providing an indication of whether said net fails to meet said minimum width; wherein steps a through f are carried out by a computer.

Claim 2

Dependent Claim 109 words

A computer-implemented method for use in making an integrated circuit, comprising the steps of: a) analyzing predefined artwork data associated with the circuit to determine a capacitance of a net of the circuit; b) determining a frequency associated with said net; c) determining a voltage swing associated with said net; d) computing a current on the basis of at least said capacitance, frequency and voltage swing; e) computing a minimum allowable width for said net on the basis of at least said current; and f) providing an indication of whether said net fails to meet said minimum width; wherein steps a through f are carried out by a computer.

Claim 3

Dependent Claim 50 words

The method recited in claim 1, further comprising the steps of: determining the number of branches of said net and a static current, if any, associated with said net; and computing said current as a function of at least said capacitance, frequency, voltage swing, number of branches and static current.

Claim 4

Dependent Claim 86 words

The method recited in claim 2, wherein said minimum width is determined for a three-layer device in accordance with the following table: ______________________________________ Bidirectional Current Unidirectional Current ______________________________________ w1 = (i/3.0 + 0.3) μm w1 = (i + 0.3) μm w2 = (i/3.0 + 0.3) μm w2 = (i + 0.3) μm w3 = (i/5.5 + 0.6) μm w3 = (i/2.0 + 0.6) μm ______________________________________ where i represents the current and w1, w2 and w3 represent the minimum widths for respective metal layers of the device.

Claim 5

Dependent Claim 30 words

The method recited in claim 2, wherein said minimum width is determined in accordance with the rule: w=(i/0.75+0.4)μm, where w is the minimum width of a layer of the device.

Claim 6

Dependent Claim 34 words

The method recited in claim 2, further comprising the step of determining whether said current is greater than the current allowed in a single contact and, if so, providing a signal indicative of that.

Claim 7

Dependent Claim 23 words

The method recited in claim 5, further comprising the step of providing a signal indicating that the number of contacts should be increased.

Claim 8

Dependent Claim 32 words

The method recited in claim 1 or claim 5, further comprising the step of graphically indicating, on artwork representing the circuit, locations at which the width of said net should be increased.

Claim 9

Independent Claim 134 words

A method of verifying the electromigration characteristics of a circuit, characterized by the following steps to be executed for each net to be examined: a) determining data about the shapes of metal which compose the net; b) determining data about the capacitance of the net; c) determining data about the average frequency of the net; d) determining data about the voltage swing of the net; e) computing, on the basis of the capacitance, average frequency and voltage swing, the absolute value of the average current needed to charge and discharge the net; f) computing, on the basis of said current, the minimum width of metal required for the net; and, g) if the net is in violation of the minimum width requirement, graphically indicating the location of the net on artwork for the circuit.

Claim 10

Independent Claim 134 words

A method of verifying the electromigration characteristics of a circuit, characterized by the following steps to be executed for each net to be examined: a) determining data about the shapes of metal which compose the net; b) determining data about the capacitance of the net; c) determining data about the average frequency of the net; d) determining data about the voltage swing of the net; e) computing, on the basis of the capacitance, average frequency and voltage swing, the absolute value of the average current needed to charge and discharge the net; f) computing, on the basis of said current, the minimum width of metal required for the net; and, g) if the net is in violation of the minimum width requirement, graphically indicating the location of the net on artwork for the circuit.

Claim 11

Dependent Claim 50 words

The method recited in claim 8, further comprising the steps of: determining the number of branches of the net and a static current, if any, associated with the net; and computing the current as a function of at least the capacitance, frequency, voltage swing, number of branches and static current.

Claim 12

Dependent Claim 86 words

The method recited in claim 9, wherein the minimum width is determined for a three-layer device in accordance with the following table: ______________________________________ Bidirectional Current Unidirectional Current ______________________________________ w1 = (i/3.0 + 0.3) μm w1 = (i/1 + 0.3) μm w2 = (i/3.0 + 0.3) μm w2 = (i/1 + 0.3) μm w3 = (i/5.5 + 0.6) μm w3 = (i/2.0 + 0.6) μm ______________________________________ where i represents the current and w1, w2 and w3 represent the minimum widths for respective metal layers of the device.

Claim 13

Dependent Claim 31 words

The method recited in claim 9, wherein the minimum width is further determined in accordance with the rule: w=(i/0.75+0.4)μm, where w is the minimum width of a layer of the device.

Claim 14

Dependent Claim 34 words

The method recited in claim 9, further comprising the step of determining whether the current is greater than the current allowed in a single contact and, if so, providing a signal indicative of that.

Claim 15

Independent Claim 100 words

An apparatus for verifying the electromigration characteristics of an integrated circuit, comprising: a) means for determining a capacitance of a net of the circuit; b) means for determining a frequency associated with said net; c) means for determining a voltage swing associated with said net; d) means for computing a current on the basis of at least said capacitance, frequency and voltage swing; e) means for computing a minimum allowable width for said net on the basis of at least said current; and f) means for providing an indication of whether said net fails to meet said minimum width requirement.

Claim 16

Independent Claim 100 words

An apparatus for verifying the electromigration characteristics of an integrated circuit, comprising: a) means for determining a capacitance of a net of the circuit; b) means for determining a frequency associated with said net; c) means for determining a voltage swing associated with said net; d) means for computing a current on the basis of at least said capacitance, frequency and voltage swing; e) means for computing a minimum allowable width for said net on the basis of at least said current; and f) means for providing an indication of whether said net fails to meet said minimum width requirement.

Claim 17

Dependent Claim 49 words

The apparatus recited in claim 13, further comprising: means for determining the number of branches of said net and a static current associated with said net; and means for computing said current as a function of at least said capacitance, frequency, voltage swing, number of branches and static current.

Claim 18

Dependent Claim 87 words

The apparatus recited in claim 14, comprising means for computing said minimum width for a three-layer device in accordance with the following table: ______________________________________ Bidirectional Current Unidirectional Current ______________________________________ w1 = (i/3.0 + 0.3) μm w1 = (i/1 + 0.3) μm w2 = (i/3.0 + 0.3) μm w2 = (i/1 + 0.3) μm w3 = (i/5.5 + 0.6) μm w3 = (i/2.0 + 0.6) μm ______________________________________ where i represents the current and w1, w2 and w3 represent the minimum widths for respective metal layers of the device.

Claim 19

Dependent Claim 32 words

The apparatus recited in claim 14, further comprising means for computing said minimum width in accordance with the rule: w=(i/0.75+0.4)μm, where w is the minimum width of a layer of the device.

Claim 20

Dependent Claim 32 words

The apparatus recited in claim 14, further comprising means for determining whether said current is greater than the current allowed in a single contact and, if so, providing an indication of such.

Claim 21

Dependent Claim 31 words

The apparatus recited in claim 13 or claim 17, further comprising means for graphically indicating on artwork representing the circuit locations at which the width of said net should be increased.

Claim 22

Independent Claim 154 words

A method for verifying the electromigration characteristics of an integrated circuit for which a capacitance data file and an artwork data file exist, comprising the following steps: a) determining whether the capacitance data for the circuit at hand is up-to-date by examining respective date codes of the capacitance data file and the artwork data file; b) running a capacitance extract program if the capacitance data is not up-to-date; c) compiling frequency, capacitance and voltage data for the circuit; d) computing average current data on the basis of said frequency, capacitance and voltage data; e) computing minimum widths for respective layers of a node of the circuit on the basis of at least said average current data; f) comparing said computed minimum widths to actual respective widths, as indicated by said artwork data, to determine where said actual widths must be increased; and g) graphically indicating the locations where said actual widths must be increased.

Claim 23

Independent Claim 154 words

A method for verifying the electromigration characteristics of an integrated circuit for which a capacitance data file and an artwork data file exist, comprising the following steps: a) determining whether the capacitance data for the circuit at hand is up-to-date by examining respective date codes of the capacitance data file and the artwork data file; b) running a capacitance extract program if the capacitance data is not up-to-date; c) compiling frequency, capacitance and voltage data for the circuit; d) computing average current data on the basis of said frequency, capacitance and voltage data; e) computing minimum widths for respective layers of a node of the circuit on the basis of at least said average current data; f) comparing said computed minimum widths to actual respective widths, as indicated by said artwork data, to determine where said actual widths must be increased; and g) graphically indicating the locations where said actual widths must be increased.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-04-24	1998-10-24	1999-04-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-04-24	2002-10-24	2003-04-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-04-24	2006-10-24	2007-04-25	$7700.00	Window Closed / Lapsed

Electromigration verification method and apparatus

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag