Anti-electromigration metal interconnection wire and preparation method and application thereof
The metal interconnected wires in the integrated circuit are irradiated by inert element ion beams, which solves the problems of poor stability and short service life caused by electromigration, and achieves the effect of significantly extending the failure time of electromigration and improving service life.
Patent Information
- Application Number
- CN202411334397.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2025-02-18
AI Technical Summary
The metal interconnected wires in integrated circuits have poor stability and short service life due to electromigration.
The metal interconnect wire is irradiated by an ion beam of inert element to suppress electromigration and thus prolong the electromigration failure time.
Through inert element ion beam irradiation treatment, the electromigration failure time of metal interconnection wires is significantly extended, the service life of nanometal interconnection is improved, and it is simple to operate and is suitable for nano-scale metal interconnection wires.
Smart Images
Figure CN119480792A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor integrated circuits and manufacturing thereof, and in particular to an electromigration resistant metal interconnection wire and a preparation method and application thereof. Background Art
[0002] In integrated circuits, metal materials such as aluminum, copper, tungsten, ruthenium, titanium and titanium nitride, tantalum and tantalum nitride are widely used to prepare metal interconnects due to their excellent electrical properties. However, metal interconnects will produce electromigration under the action of electric current and Joule heat. The electromigration phenomenon can cause the metal interconnects to break and thus affect the normal operation of the chip. Therefore, electromigration failure time is one of the important indicators for measuring the reliability of metal interconnects. Generally, the best way to prevent electromigration in metal interconnects is to increase the line width of the metal lines. However, with the gradual development of chip manufacturing technology, the scale of metal interconnects in chips has become smaller and smaller. At present, the size of metal interconnects has reached about 20 nanometers. The extremely small line width leads to a very large current density (>10 6 A / cm 2 ), and high current density will lead to shorter electromigration failure time in metal interconnect wires, and the life of metal interconnect wires will also be shorter. Size limitations also make the method of increasing line width not applicable to today's chip processing industry.
[0003] Therefore, the prior art still needs to be improved and developed. Summary of the invention
[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an anti-electromigration metal interconnect wire and a preparation method and application thereof, aiming to solve the problem of poor stability and short service life of metal interconnect wires in integrated circuits due to electromigration.
[0005] The technical solution of the present invention is as follows:
[0006] A first aspect of the present invention provides a method for preparing an electromigration resistant metal interconnect wire, comprising the steps of:
[0007] Providing metal interconnect wires;
[0008] Using an ion beam of an inert element to irradiate the metal interconnect wire to obtain an electromigration resistant metal interconnect wire;
[0009] The inert ion irradiation dose of the anti-electromigration metal interconnection wire is 1×10 5 ~1×10 19 ions / cm 2 .
[0010] The preferred technical solution is that there are three ion beam irradiation methods:
[0011] Focused ion beam scanning irradiation method: Figure 1 As shown, this approach uses a highly focused ion beam to precisely irradiate ions into a target area;
[0012] Mobile scanning irradiation method: Figure 2 As shown, the target area is covered by moving and scanning the ion beam;
[0013] Full coverage irradiation method: Figure 3 As shown, a wider ion beam is used to directly cover the entire surface area.
[0014] In a preferred technical solution, the material of the metal interconnection wire is selected from one or more of copper, gold, silver, aluminum, nickel, titanium, chromium, platinum, palladium, tungsten, iridium, zinc, cobalt, ruthenium and molybdenum.
[0015] According to a preferred technical solution, the inert element is selected from one or more of helium, neon, argon, krypton and xenon.
[0016] According to a preferred technical solution, the voltage range of the ion beam is 1V to 300kV.
[0017] A preferred technical solution is that the method for preparing the metal interconnection wire comprises the steps of:
[0018] providing a substrate;
[0019] preparing a metal thin film on the substrate;
[0020] The metal film is patterned to obtain metal interconnection wires.
[0021] According to a preferred technical solution, the cross section of the metal interconnection wire is rectangular, the line width of the metal interconnection wire is 5 to 1000 nm, and the thickness of the metal interconnection wire is 4 to 300 nm.
[0022] According to a preferred technical solution, the metal interconnection wire is heat treated.
[0023] According to a preferred technical solution, the heat treatment temperature is 200-400° C. and the time is 10-30 minutes.
[0024] A second aspect of the present invention provides an electromigration resistant metal interconnect wire, which is prepared by the preparation method described in the first aspect.
[0025] A third aspect of the present invention provides an application of the electromigration resistant metal interconnect wire as described in the first aspect in an integrated circuit.
[0026] Beneficial effects: Compared with the prior art, the advantages of the present invention are:
[0027] (1) Do not change the structure of the metal interconnect wire itself;
[0028] (2) It can be applied to nanoscale metal interconnects with smaller dimensions;
[0029] (3) The operation is relatively simple, no complicated processing methods are required, and the processing time is short;
[0030] (4) Compatible with other process steps in integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 Schematic diagram of using a focused inert ion beam to irradiate metal wires on a chip.
[0032] Figure 2 This is a schematic diagram of using a mobile scanning ion implanter to irradiate metal wires on a chip.
[0033] Figure 3 This is a schematic diagram of using a surface-covering ion implanter to irradiate metal wires on a chip.
[0034] Figure 4 This is a high-resolution transmission electron microscopy image of the gold nanostructure after helium ion irradiation in Example 1.
[0035] Figure 5 This is a graph showing the electron energy loss spectrum characterization results of the gold nanostructure after helium ion irradiation in Example 1.
[0036] Figure 6 It is a result diagram of the volt-ampere curve test of the anti-electromigration copper metal interconnection wire of Example 2 and the copper metal interconnection wire of Comparative Example 1.
[0037] Figure 7 It is a result diagram of a constant current density test of the anti-electromigration copper metal interconnection wire of Example 2 and the copper metal interconnection wire of Comparative Example 1.
[0038] Figure 8 This is a result diagram of the anti-electromigration copper metal interconnect wire of Example 2 after being energized at a constant current of 7.5 mA for 7500 seconds.
[0039] Fig. 9 This is a graph showing the result of the copper metal interconnect wire of Comparative Example 1 after being energized at a constant current of 7.5 mA for 122 seconds. DETAILED DESCRIPTION
[0040] The present invention provides an electromigration resistant metal interconnect wire and a preparation method and application thereof. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below.
[0041] The commonly used methods to improve the stability of nanometal interconnects are to increase the size of metal interconnect wires and coat the surface of the wires with stabilizing materials. However, increasing the size of metal nanowires is contrary to the size requirements in chip processing, and the coating method with stabilizing materials has limited effect on inhibiting the electromigration of metal nanowires.
[0042] Based on this, an embodiment of the present invention provides a method for preparing an electromigration resistant metal interconnect wire, comprising the steps of:
[0043] providing metal interconnect wires;
[0044] Using an ion beam of an inert element to irradiate the metal interconnect wire to obtain an electromigration resistant metal interconnect wire;
[0045] The inert ion irradiation dose of the anti-electromigration metal interconnection wire is 1×10 5 ~1×10 19 ions / cm 2 .
[0046] Specifically, in the metal interconnection wire that has not been irradiated, the metal atoms in the grains are more stable. When the power is turned on, it is mainly the metal atoms at the grain boundary and the metal atoms on the surface of the material that are electromigrating, so it is easy to break. The embodiment of the present invention uses an ion beam of an inert element to irradiate the metal interconnection wire, irradiating a certain dose of inert element ions in the metal interconnection wire to inhibit electromigration, thereby extending the electromigration failure time of the metal interconnection wire and improving the service life of the nano metal interconnection.
[0047] Among them, the ion beam irradiation method is as follows Figure 1 or Figure 2 or Figure 3 As shown, but not limited to.
[0048] like Figure 4 and Figure 5 As shown, in the present invention, the principle of irradiating inert element ions to suppress electromigration mainly includes two aspects: first, the ion beam irradiation of the inert element suppresses the migration of metal atoms at the grain boundaries of the metal interconnect wire. When the power is turned on, the momentum of the electrons is mainly transferred to the metal atoms in the grains rather than the metal atoms at the grain boundaries, so the electromigration failure time can be greatly extended. Second, the ion beam irradiation of the inert element forms an amorphous layer on the surface of the metal interconnect wire, suppressing the migration of metal atoms on the surface of the metal interconnect wire, thereby avoiding fracture.
[0049] Among them, inert elements are selected for ion beams mainly because they have extremely high chemical stability. Inert elements are not easy to react chemically with other substances, so they will not react with other materials in the circuit to form new compounds, thus avoiding potential contamination problems.
[0050] The inert ion irradiation dose was controlled to be 1×10 5 ~1×10 19 ions / cm 2 The purpose is to improve the anti-electromigration performance while maintaining good electrical performance. Preferably, the inert ion irradiation dose is 1×10 10 ~1×10 19 ions / cm 2 More preferably, the inert ion irradiation dose is 1×10 15 ~1×10 19 ions / cm 2 , but not limited to this.
[0051] In some embodiments, the material of the metal interconnect wire is selected from one or more of copper, gold, silver, aluminum, nickel, titanium, chromium, platinum, palladium, tungsten, iridium, zinc, cobalt, ruthenium, and molybdenum, but is not limited thereto.
[0052] In some embodiments, the inert element is selected from one or more of helium, neon, argon, krypton, and xenon, but is not limited thereto.
[0053] In some embodiments, the voltage range of the ion beam is 1V to 300kV; preferably, the voltage range of the ion beam is 1V to 100kV; more preferably, the voltage range of the ion beam is 800V to 50kV; further preferably, the voltage range of the ion beam is 10kV to 50kV, but not limited thereto.
[0054] In some embodiments, the method for preparing the metal interconnect wire comprises the steps of:
[0055] providing a substrate;
[0056] preparing a metal thin film on the substrate;
[0057] The metal film is patterned to obtain metal interconnection wires.
[0058] In some embodiments, the thickness of the metal film is 4 to 300 nm.
[0059] Furthermore, in some embodiments, the method for preparing the metal film on the substrate is selected from one of electroplating, electron beam evaporation, laser pulse deposition, thermal evaporation, sputtering, atomic layer deposition, chemical vapor deposition, hydrothermal method, molecular beam epitaxy, and plasma enhanced chemical vapor deposition, but is not limited thereto.
[0060] Furthermore, in a specific embodiment, the method for preparing the metal interconnection wire comprises the steps of:
[0061] Expose the photoresist using an exposure technique to obtain nanowires with a line width of 5 to 1000 nm, evaporate a metal film with a thickness of 4 to 300 nm, and peel off to obtain metal interconnect wires of corresponding sizes. Preferably, the line width of the nanowire is 5 to 500 nm, and the thickness of the metal film is 4 to 100 nm; more preferably, the line width of the nanowire is 5 to 250 nm, and the thickness of the metal film is 4 to 50 nm, but not limited thereto.
[0062] Furthermore, in another specific embodiment, the method for preparing the metal interconnection wire comprises the steps of:
[0063] A substrate is selected, and a metal film with a thickness of 4 to 300 nm is prepared by magnetron sputtering. After sputtering, annealing is performed. A photoresist with a thickness of 10 to 1000 nm is spin-coated on the annealed metal film, and patterning is performed using an exposure technique to obtain nanowires with a line width of 50 to 1000 nm. After etching using an inductively coupled plasma etching or reactive ion etching device, the residual glue is removed to obtain metal interconnect wires of corresponding sizes. Preferably, the thickness of the metal film is 4 to 100 nm, the thickness of the photoresist is 10 to 500 nm, and the line width of the nanowire is 50 to 1000 nm; more preferably, the thickness of the metal film is 4 to 50 nm, the thickness of the photoresist is 10 to 250 nm, and the line width of the nanowire is 50 to 250 nm.
[0064] In some other embodiments, the method for preparing the metal interconnect wire comprises the steps of:
[0065] Providing a patterned metal seed layer;
[0066] Electroplating is performed on the metal seed layer to obtain metal interconnection wires.
[0067] In some embodiments, the cross-section of the metal interconnection wire is rectangular, the line width of the metal interconnection wire is 5 to 1000 nm, and the thickness of the metal interconnection wire is 4 to 300 nm. Preferably, the line width of the metal interconnection wire is 5 to 500 nm, and the thickness of the metal interconnection wire is 4 to 100 nm; more preferably, the line width of the metal interconnection wire is 5 to 250 nm, and the thickness of the metal interconnection wire is 4 to 50 nm, but not limited thereto. The line width of the metal interconnection wire refers to the length of the parallel sides of the rectangle of the cross-section, and the thickness of the metal interconnection wire refers to the length of the vertical sides of the rectangle of the cross-section. In addition, the cross-section of the metal interconnection wire may also be other shapes, such as circular, elliptical, square, triangular, polygonal, etc.
[0068] In some embodiments, the metal interconnection wire is subjected to heat treatment. Specifically, if the grains in the metal interconnection wire are too small, it is necessary to perform heat treatment before irradiating the metal interconnection wire with an ion beam of an inert element. After the heat treatment, the grains in the metal interconnection wire can grow, so that after the irradiation treatment, the electromigration can be more significantly inhibited.
[0069] Furthermore, in some embodiments, the heat treatment is performed at a temperature of 200 to 400° C. and for a time of 10 to 30 minutes.
[0070] In some embodiments, the irradiation treatment is performed by an ion microscope.
[0071] Furthermore, in some embodiments, when an ion microscope is used for irradiation treatment, the metal interconnect wire is subjected to focused scanning irradiation at a voltage of 1 to 30 kV, the irradiation current is 0.1 to 10 pA, the irradiation time is 1 to 100 μs, and the ion beam step is 0.5 to 10 nm.
[0072] In some embodiments, the irradiation treatment is performed by an ion implanter.
[0073] Furthermore, in some embodiments, when an ion implanter is used for irradiation treatment, the metal interconnect wire is irradiated at an acceleration voltage of 1V to 300kV, and the current of the ion implanter is set to 500nA to 10A.
[0074] An embodiment of the present invention provides an electromigration resistant metal interconnect wire, which is prepared by the preparation method described above.
[0075] An embodiment of the present invention provides an application of the above-mentioned anti-electromigration metal interconnection wire in an integrated circuit.
[0076] The present invention will be further described below by means of specific examples.
[0077] Example 1
[0078] This example illustrates the principle of inert ion irradiation to suppress electromigration of metal nanowires. A 120-nanometer-thick exposed polymethyl methacrylate (PMMA) was spin-coated on a 20-nanometer-thick silicon nitride film, and the PMMA was exposed and developed using electron beam exposure technology. A gold film was deposited by electron beam evaporation and peeled off to obtain a patterned gold nanostructure. The gold nanostructure was irradiated with helium ions accelerated by 30 kV, and the irradiation dose was 1×10 17 ions / cm 2 . Transmission electron microscopy was used to characterize the gold nanostructures after helium ion irradiation. Figure 4The high-resolution transmission electron microscopy image shows that an amorphous layer of about 2 nanometers is formed on the surface of the gold nanostructure after helium ion irradiation. Figure 5 Electron energy loss spectrum characterization shows that helium ions are mainly distributed on the surface of the gold nanostructure, forming a layer of amorphous gold / helium alloy on the surface of the gold nanostructure.
[0079] Example 2
[0080] This embodiment provides an electromigration resistant copper metal interconnect wire, and the preparation method thereof is as follows:
[0081] Electron beam lithography was used to expose polymethyl methacrylate (PMMA) to obtain nanowires with a line width of 150 nm, and titanium with a thickness of 1 nm and copper with a thickness of 25 nm were evaporated. After peeling, copper metal interconnects of corresponding sizes were obtained, which were heat treated in a rapid thermal annealing device at a temperature of 250°C for 20 min. A helium ion microscope was used to focus and scan the obtained copper metal interconnects at a voltage of 30 kV. The irradiation current was 1 pA, the irradiation time was 40 μs, the ion beam step was 0.5 nm, and the number of irradiated ions was 1×10 18 ions / cm 2 , and obtain electromigration-resistant copper metal interconnect wire.
[0082] Example 3
[0083] This embodiment provides a ruthenium metal interconnect wire that resists electromigration, and the preparation method thereof is as follows:
[0084] Sapphire glass was selected as the substrate, and a ruthenium film with a thickness of 25 nm was prepared by magnetron sputtering. After sputtering, annealing was performed. Hydrogen siloxane (HSQ) with a thickness of 25 nm was spin-coated on the annealed ruthenium film, and patterning was performed using exposure technology to obtain nanowires with a line width of 100 nm. After etching using an inductively coupled plasma etching device, the residual glue was removed to obtain ruthenium metal interconnect wires of corresponding sizes. The obtained ruthenium metal interconnect wires were irradiated with helium ions using an ion implanter at an accelerating voltage of 50 kV. The implanter current was set to 1 μA, and the number of irradiated ions was 1×10 16 ions / cm 2 , and obtain ruthenium metal interconnect wires that are resistant to electromigration.
[0085] Example 4
[0086] This embodiment provides an electromigration resistant molybdenum metal interconnect wire, and the preparation method thereof is as follows:
[0087] A silicon wafer with a 200nm thick oxide layer on the surface was selected as the substrate, and a 25nm thick molybdenum film was prepared by magnetron sputtering. After sputtering, annealing was performed. Hydrogen siloxane (HSQ) with a thickness of 25nm was spin-coated on the annealed molybdenum film, and patterned using exposure technology to obtain nanowires with a line width of 200nm. After etching using an inductively coupled plasma etching device, the residual glue was removed to obtain a molybdenum metal interconnect wire of the corresponding size. The obtained molybdenum metal interconnect wire was irradiated with neon ions using an ion implanter at an acceleration voltage of 10kV. The implanter current was set to 500nA, and the number of irradiated ions was 1×10 15 ions / cm 2 , and obtain electromigration-resistant molybdenum metal interconnect wire.
[0088] Comparative Example 1
[0089] This comparative example provides a copper metal interconnection wire, and its preparation method is the same as the preparation method of the copper metal interconnection wire in Example 2, except that: no heat treatment and helium ion irradiation are performed on it.
[0090] Comparative Example 2
[0091] This comparative example provides a ruthenium metal interconnection wire, and its preparation method is the same as the preparation method of the ruthenium metal interconnection wire in Example 3, except that: it is not subjected to helium ion irradiation.
[0092] Comparative Example 3
[0093] This comparative example provides a molybdenum metal interconnection wire, and its preparation method is the same as the preparation method of the molybdenum metal interconnection wire in Example 4, except that: it is not subjected to neon ion irradiation.
[0094] The electromigration-resistant copper metal interconnect wire obtained in Example 2 and the copper metal interconnect wire obtained in Comparative Example 1 were respectively subjected to electrical testing using a four-probe station with a current density of 1.5×10 8 A / cm 2 The electromigration failure time was tested at a constant current density of 1.5 ℃. After the test, it was found that the electromigration failure time required for the electromigration-resistant copper metal interconnect wire obtained in Example 2 was longer at the same current density. The specific results are as follows: Figure 6 and Figure 7 shown.
[0095] Depend on Figure 6 It can be seen that the maximum current density that can pass through the anti-electromigration copper metal interconnect wire after helium ion irradiation in Example 2 is 1.81×10 8 A / cm 2 The maximum current density of the copper metal interconnect wire that has not been irradiated with helium ions in Comparative Example 1 is only 0.81A / cm2 .
[0096] Depend on Figure 7 It can be seen that the anti-electromigration copper metal interconnect wire after helium ion irradiation in Example 2 did not break after power was applied, and the voltage was not the open circuit voltage; while the copper metal interconnect wire that was not irradiated with helium ions in Comparative Example 1 broke quickly after power was applied, the circuit was open, the resistance was infinite, the voltage became the circuit-breaking protection voltage of 2V, and the electromigration rupture time was 122 seconds.
[0097] Depend on Figure 8 It can be seen that the electromigration resistant copper metal interconnect wire after helium ion irradiation in Example 2 was not broken after being energized at a constant current of 7.5 mA for 7500 seconds.
[0098] Depend on Fig. 9 It can be seen that the copper metal interconnect wire in Comparative Example 1 that was not irradiated with helium ions broke after being energized with a constant current of 7.5 mA for 122 seconds.
[0099] The ruthenium metal interconnect wires obtained in Example 3 and the ruthenium metal interconnect wires obtained in Comparative Example 2 were subjected to electrical tests using a four-probe station. After the samples were heated to 300°C, a current density of 3×10 7 A / cm 2 The electromigration failure time was tested with a constant current of . After the test, it was found that the electromigration failure time of the electromigration-resistant ruthenium metal interconnect wire obtained in Example 3 was longer at the same current density.
[0100] The electromigration-resistant molybdenum metal interconnect wire obtained in Example 4 and the molybdenum metal interconnect wire obtained in Comparative Example 3 were respectively subjected to electrical testing using a four-probe station. After the samples were heated to 200°C, a current density of 3×10 7 A / cm 2 The electromigration failure time was tested with a constant current of . After the test, it was found that the electromigration failure time required for the electromigration-resistant molybdenum metal interconnect wire obtained in Example 4 was longer at the same current density.
[0101] In summary, the present invention provides an anti-electromigration metal interconnection wire and a preparation method and application thereof. The preparation method comprises: providing a metal interconnection wire; irradiating the metal interconnection wire with an ion beam of an inert element to obtain an anti-electromigration metal interconnection wire; wherein the inert ion irradiation dose of the anti-electromigration metal interconnection wire is 1×10 5 ~1×10 19 ions / cm 2. The irradiation treatment of the present invention, on the one hand, inhibits the migration of metal atoms at the grain boundaries of the metal interconnect wires, so that when power is turned on, the momentum of the electrons is mainly transferred to the metal atoms in the grains rather than the metal atoms at the grain boundaries. The grains are relatively more stable than the grain boundaries, so the electromigration failure time can be greatly prolonged; on the other hand, an amorphous layer is formed on the surface of the metal interconnect wires, which inhibits the migration of metal atoms on the surface of the metal interconnect wires, thereby avoiding fracture. The preparation method does not change the structure of the metal interconnect wires, is suitable for nanoscale metal interconnect wires with smaller scales, is simple to operate, has a short processing time, does not require complex processing methods, and is compatible with other process steps in integrated circuits.
[0102] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.
Claims
1. A method for preparing an electromigration resistant metal interconnect wire, characterized in that: Includes steps: Providing metal interconnect wires; Using an ion beam of an inert element to irradiate the metal interconnect wire to obtain an electromigration resistant metal interconnect wire; The inert ion irradiation dose of the anti-electromigration metal interconnection wire is 1×10 5 ~1×10 19 ions / cm 2 .
2. The preparation method according to claim 1, characterized in that: The material of the metal interconnection wire is selected from one or more of copper, gold, silver, aluminum, nickel, titanium, chromium, platinum, palladium, tungsten, iridium, zinc, cobalt, ruthenium, and molybdenum.
3. The preparation method according to claim 1, characterized in that: The inert element is selected from one or more of helium, neon, argon, krypton and xenon.
4. The preparation method according to claim 1, characterized in that: The voltage range of the ion beam is 1V to 300kV.
5. The preparation method according to claim 1, characterized in that: The method for preparing the metal interconnection wire comprises the steps of: providing a substrate; preparing a metal thin film on the substrate; The metal film is patterned to obtain metal interconnection wires.
6. The preparation method according to claim 1, characterized in that: The cross section of the metal interconnection wire is rectangular, the line width of the metal interconnection wire is 5 to 1000 nm, and the thickness of the metal interconnection wire is 4 to 300 nm.
7. The preparation method according to claim 1, characterized in that: The metal interconnection wire is heat treated.
8. The preparation method according to claim 7, characterized in that: The heat treatment temperature is 200-400° C. and the time is 10-30 minutes.
9. An electromigration resistant metal interconnect wire, characterized in that: The preparation is obtained by the preparation method according to any one of claims 1 to 8.
10. Use of the electromigration resistant metal interconnection wire as claimed in claim 9 in an integrated circuit.