Peak current calculation and evaluation method for metal interconnects

Abstract

The present invention provides a peak current calculation and evaluation method for metal interconnects, providing multiple groups of substrates; forming metal interconnect structures with different design widths on the multiple groups of substrates; selecting dies on the multiple groups of substrates, applying gradually increasing pulse voltages to the multiple groups of metal interconnect structures, and obtaining data on the maximum peak current density that the multiple groups of metal interconnect structures can withstand; fitting the relationship between the peak current density and the design width according to the data to obtain a prediction interval; obtaining a fitting curve according to the lower limit of the prediction interval, and using the fitting curve as a reference for a process verification test standard. The present invention summarizes the corresponding relationship formula for the measured data of the metal interconnect width and the peak current density, and the formula will provide a reference for the design of metal interconnects; statistically analyzing the measured data to obtain a 95% prediction interval, and the lower limit of the prediction interval can be used as a reference for the reliability test standard.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for calculating and evaluating the peak current of a metal interconnection line. Background Art

[0002] Circuit reliability is defined as the ability of a system or component to perform its specified function under specified conditions and within a specified timeframe. Since the advent of integrated circuits, reliability research and testing have been a crucial component of IC design, process R&D, and product production. Process reliability assessment uses specially designed structures to test and evaluate process-related wearout mechanisms in integrated circuits.

[0003] The peak current density that can be withstood by back-end interconnects in integrated circuits is becoming increasingly important as the node size decreases, and a systematic test specification and evaluation method is required. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for calculating and evaluating the peak current of metal interconnects, which is used to solve the problem in the prior art that the peak current density that the back-end interconnects of integrated circuits can withstand is increasingly important as the node decreases, and there is a lack of systematic testing specifications and evaluation methods.

[0005] To achieve the above-mentioned and other related objectives, the present invention provides a method for calculating and evaluating the peak current of a metal interconnect, comprising:

[0006] Step 1: providing multiple sets of substrates;

[0007] Step 2: forming metal interconnection structures with different design widths on multiple groups of the substrates;

[0008] Step 3: Select multiple groups of dies at typical locations on the substrate, and apply gradually increasing pulse voltages to the multiple groups of metal interconnect structures obtained in Step 2 to obtain data on the maximum peak current density that the multiple groups of metal interconnect structures can withstand, where the typical locations are substrate locations that meet yield standards in actual production processes;

[0009] Step 4: fitting the relationship between peak current density and design width according to the data obtained in step 3 to obtain a prediction interval;

[0010] Step 5: Obtain a fitting curve based on the lower limit of the prediction interval, and the fitting curve serves as a reference for the process verification test standard.

[0011] Preferably, the number of the multiple groups of substrates in step one is three.

[0012] Preferably, the different design sizes in step 2 are different design widths.

[0013] Preferably, the different design widths include 1 times the reference width, 2 times the reference width, 4 times the reference width, 8 times the reference width, 12 times the reference width, 16 times the reference width, 20 times the reference width, 40 times the reference width, 60 times the reference width and 80 times the reference width, wherein the reference width is defined as the width value set for the metal interconnection line.

[0014] Preferably, the pulse voltage in step three is provided by a transmission line pulser.

[0015] Preferably, the prediction interval in step 4 is a 95% prediction interval.

[0016] Preferably, the fitting curve obtained in step 5 is in the form of J peak =a / (Width-n)+b, where J peak is the peak current density, a, b and n are all constants, and Width is the designed width.

[0017] Preferably, the method is applicable to a peak current calculation and evaluation method for back-end interconnects of integrated circuits.

[0018] As described above, the peak current calculation and evaluation method of the metal interconnection line of the present invention has the following beneficial effects:

[0019] Based on the measured data of metal interconnect width and peak current density, a corresponding relationship formula was summarized, which will provide a reference for metal interconnect design; a statistical analysis of the measured data was performed to obtain a 95% prediction interval, and the lower limit of the prediction interval can be used as a reference for reliability testing standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is a schematic flow chart of the method provided by the present invention;

[0021] Figure 2 Shown is a schematic diagram of the fitting curve provided by the present invention. DETAILED DESCRIPTION

[0022] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] See also Figure 1The present invention provides a method for calculating and evaluating the peak current of a metal interconnect line, comprising:

[0024] Step 1: providing multiple groups of substrates as test groups for acquiring data;

[0025] In an optional embodiment, the substrates in step 1 are in groups of three.

[0026] Step 2: forming metal interconnection structures with different design widths on multiple groups of substrates;

[0027] In an optional embodiment, the different design dimensions in step 2 are different design widths of the metal interconnection lines, and the thickness of the metal interconnection lines remains unchanged. The different design widths include 1 times the reference width, 2 times the reference width, 4 times the reference width, 8 times the reference width, 12 times the reference width, 16 times the reference width, 20 times the reference width, 40 times the reference width, 60 times the reference width and 80 times the reference width, wherein the reference width is defined as the width value set for the metal interconnection lines.

[0028] Step 3: Select multiple groups of dies at typical locations on the substrate, and apply gradually increasing pulse voltages to the multiple groups of metal interconnect structures obtained in Step 2 to obtain data on the maximum peak current density that the multiple groups of metal interconnect structures can withstand, where the typical locations are substrate locations that meet yield standards in actual production processes;

[0029] In an optional embodiment, the pulse voltage in step three is provided by a transmission line pulser.

[0030] Step 4, please refer to Figure 2 , according to the data obtained in step 3, the relationship between the peak current density and the design width is fitted to obtain the prediction interval, where the design width is the horizontal axis and the peak current density is the vertical axis. Since multiple groups of substrates are set, the same design width corresponds to multiple peak current densities in the prediction interval;

[0031] In an optional implementation scheme, the prediction interval in step 4 is a 95% prediction interval. The prediction interval uses an interval to estimate the range of the overall parameter according to a certain probability or credibility (1-α). This range is usually called the credible interval or confidence interval (CI) of the parameter. The predetermined probability (1-α) is called the credibility or confidence level, which is usually 95% or 99%.

[0032] Step 5: Obtain a fitting curve based on the lower limit of the prediction interval as the peak current density that the metal interconnect structure can withstand. The fitting curve serves as a reference for the process verification test standard.

[0033] In an optional embodiment, the fitting curve obtained in step five is in the form of Jpeak=a / (Width-n)+b, wherein Jpeak is the peak current density, a, b and n are all constants, and Width is the designed width.

[0034] In an optional embodiment, the method is applicable to a peak current calculation and evaluation method for back-end interconnects of an integrated circuit.

[0035] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0036] In summary, this invention, based on measured data on metal interconnect width and peak current density, develops a formula that provides a reference for metal interconnect design. Statistical analysis of the measured data yields a 95% prediction interval, the lower limit of which serves as a reference for reliability testing. Therefore, this invention effectively overcomes the shortcomings of existing technologies and possesses high industrial applicability.

[0037] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for calculating and evaluating the peak current of a metal interconnect, characterized in that: At least: Step 1, providing multiple groups of substrates; Step 2: forming metal interconnection line structures with different design sizes on multiple groups of the substrates, wherein the different design sizes are different design widths of the metal interconnection lines; Step 3, selecting multiple groups of dies on the substrate, applying gradually increasing pulse voltages to the multiple groups of metal interconnection line structures obtained in step 2, and obtaining data on the maximum peak current density that the multiple groups of metal interconnection line structures can withstand; Step 4: fitting the relationship between the peak current density and the design width according to the data obtained in step 3 to obtain a prediction interval, wherein the prediction interval uses an interval to estimate the range of the overall parameter according to probability or credibility (1-α), wherein the design width is the horizontal axis and the peak current density is the vertical axis, and the same design width corresponds to multiple peak current densities; Step 5: Obtain a fitting curve according to the lower limit of the prediction interval, and the fitting curve is used as a reference for the process verification test standard.

2. The peak current calculation and evaluation method of metal interconnection line according to claim 1, characterized in that: The number of the multiple groups of substrates in step one is three.

3. The peak current calculation and evaluation method of metal interconnection line according to claim 1, characterized in that: The different design widths include 1 times the reference width, 2 times the reference width, 4 times the reference width, 8 times the reference width, 12 times the reference width, 16 times the reference width, 20 times the reference width, 40 times the reference width, 60 times the reference width and 80 times the reference width, wherein the reference width is defined as the width value set for the metal interconnect line.

4. The peak current calculation and evaluation method of metal interconnection line according to claim 1, characterized in that: The pulse voltage in step 3 is provided by a transmission line pulser.

5. The peak current calculation and evaluation method of metal interconnection line according to claim 1, characterized in that: The prediction interval in step 4 is a 95% confidence prediction interval.

6. The peak current calculation and evaluation method of metal interconnection line according to claim 1, characterized in that: The fitting curve obtained in step 5 is in the form of J peak =a / (Width-n)+b, where J peak is the peak current density, a, b and n are all constants, and Width is the designed size.

7. The peak current calculation and evaluation method of metal interconnection line according to claim 1, characterized in that: This method is suitable for the peak current calculation and evaluation method of the back-end interconnection lines of integrated circuits.

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