Repair process for selective atomic layer
By employing selective atomic layer repair (SIP) technology, copper atomic layers are deposited through the reaction of specific precursors with reducing gases. This solves the problem of microscopic defects in copper interconnects, improves the electromigration resistance and lifespan of copper interconnects, and protects the dielectric layer, achieving higher conductivity and thermal stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-03-27
AI Technical Summary
Existing technologies struggle to effectively repair microscopic defects, such as pores and grain boundary gaps, in copper interconnects, leading to increased electromigration, which affects chip reliability and lifespan. Furthermore, high-temperature annealing processes may damage the ultra-low k dielectric layer.
The selective atomic layer repair process employs a specific precursor, such as bis(hexafluoroacetylacetone)copper(II) or (trimethylsilanemethyl)copper(I), which reacts with a reducing gas in the ALD reaction chamber to selectively deposit copper atomic layers to fill defects. Combined with a mild annealing process, this achieves densification repair.
It enables precise repair of internal defects in copper interconnects, enhances resistance to electromigration, extends service life, avoids damage to the dielectric layer caused by high-temperature annealing, and improves conductivity and thermal stability.
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Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor fabrication technology, specifically to a repair process for selective atomic layers. Background Technology
[0002] In semiconductor manufacturing processes, metal interconnects are used to connect the various transistors in integrated circuits. Their performance and reliability directly affect the overall performance, power consumption, and lifespan of the chip. As technology nodes advance to 7nm and below, copper interconnect technology still faces significant challenges.
[0003] In the back-end processes of BEOL (Body-on-Order) circuitry, copper interconnects are typically formed using electrochemical plating. To ensure complete filling of trenches and vias, overfill technology is often employed. However, this overfill technique easily creates tiny voids and gaps within the copper interconnects, particularly at grain boundaries. These internal defects become areas of concentrated current density when the chip is powered on, significantly exacerbating electromigration. Electromigration leads to increased interconnect resistance, performance degradation, and even ultimately, open circuits, severely impacting the long-term reliability of the chip.
[0004] Currently, high-temperature annealing is commonly used to improve the grain structure of electroplated copper wires in order to increase their density. However, traditional annealing processes have limited ability to repair deep pores or grain boundary gaps that have already formed, and cannot fundamentally eliminate these defects. Furthermore, the high-temperature process may also cause thermal damage to sensitive materials such as the already formed ultra-low k dielectric layer.
[0005] Therefore, there is an urgent need to develop a new process to repair the microscopic defects inside composite metal interconnects. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a repair process for selective atomic layers, solving the problems mentioned in the background section.
[0007] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, a repair process for selective atomic layers is provided, wherein a semiconductor structure is placed in an ALD reaction chamber, a first precursor is first introduced to selectively adsorb on the surface of a metal interconnect, a second precursor is then introduced to react with the first precursor adsorbed on the surface of the metal interconnect, and the selective adsorption and reaction steps are repeated to obtain a metal atomic layer. The first precursor is selected from bis(hexafluoroacetylacetone)copper(II) or (trimethylsilanemethyl)copper(I); the second precursor is a reducing gas.
[0008] The semiconductor structure of this invention includes a substrate and a dielectric layer formed on the substrate. Metal interconnects are embedded within the dielectric layer. The surfaces of the metal interconnects are exposed, and micro-defects such as pores and / or grain boundaries exist within them. The metal interconnects are copper interconnects, and the dielectric layer is at least one of silicon oxide, silicon nitride, or carbon-doped silicon oxide. First, a first precursor is introduced and selectively adsorbed onto the surface of the metal interconnects with micro-defects. The selected bis(hexafluoroacetylacetone)copper(II) or (trimethylsilanemethyl)copper(I) exhibits chemoselectivity towards metallic copper, leading to a reduction reaction. This reduces the first precursor deposited on the surface of the metal interconnects to a layer of target metal atoms. Simultaneously, the energy and active byproducts generated during the reaction promote the migration and filling of metal atoms into the micro-defects. After these two steps, the process is repeated to complete the filling and repair of the micro-defects within the metal interconnects, forming a dense metal interconnect structure.
[0009] Preferably, the reducing gas is selected from at least one of hydrogen, formic acid, and ethanol.
[0010] Preferably, the temperature inside the ALD reaction chamber is 100~300℃ and the pressure is 0.1~10 Torr.
[0011] Preferably, the selective adsorption time is 1~5s; The reaction time is 1-5 seconds.
[0012] Preferably, after the selective adsorption and reaction are completed, an inert gas is introduced for purging.
[0013] Preferably, the number of times the selective adsorption and reaction steps are repeated is 2 to 50.
[0014] Preferably, after completing the repeated selective adsorption and reaction steps, the semiconductor structure is further subjected to an annealing treatment at a temperature of 150~400℃. Beneficial effects
[0015] This invention provides a repair process for selective atomic layers. It has the following beneficial effects: (1) The present solution provides a repair process for selective atomic layers. By using specific precursor materials to react with the copper metal surface, a high degree of selectivity is achieved in the repair process. After a reduction reaction, the deposition reaction occurs only on the exposed copper interconnect surface and in the pores and gaps inside, and does not deposit on the dielectric layer, thereby achieving precise repair.
[0016] (2) The solution provides a repair process for selective atomic layers, which is repaired under mild conditions. It is compatible with ultra-low k dielectric materials and can avoid damage caused by high temperature annealing.
[0017] (3) The solution provides a repair process for selective atomic layers. Through multiple ALD cycles, the newly deposited metal atomic layers can fully fill the pores and grain boundaries inside the copper interconnect, forming a denser and more complete metal structure. This allows for a uniform distribution of current density and withstands stronger current surges, thereby significantly improving the electromigration resistance of the copper interconnect and extending its service life.
[0018] (4) The present solution provides a repair process for selective atomicity. After ALD deposition, annealing is performed to further promote the crystallization and fusion of atoms in the repair area, resulting in a more stable repair effect. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] To better illustrate the content of this invention, the following description is provided in conjunction with specific embodiments.
[0021] Example 1 This invention provides a repair process for selective atomic layers, the specific steps of which are as follows: S1. Provide a 12-inch wafer in which copper interconnects are formed in a SiCOH dielectric layer and have undergone preliminary electrochemical plating and annealing, with crystal gaps inside the copper wires; S2. Place the wafer in the ALD reaction chamber, and set the temperature inside the chamber to 200°C and the pressure to 1 Torr. S3. Pulse-inject bis(hexafluoroacetylacetone)copper(II) into the ALD reaction chamber for 3 seconds to allow it to be selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove excess bis(hexafluoroacetylacetone)copper(II) from the chamber. S5. Pulse hydrogen gas into the ALD reaction chamber for 3 seconds to react with the adsorbed bis(hexafluoroacetylacetone)copper(II), deposit a copper atom layer, and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 20 times. Finally, anneal the wafer at 300°C for 30 minutes under a nitrogen atmosphere to complete the repair.
[0022] Example 2 S1. Provide wafers from the same batch as in S1 of Example 1; S2. Place the wafer in the ALD reaction chamber, and set the temperature inside the chamber to 180°C and the pressure to 2 Torr. S3. Pulse-inject (trimethylsilanemethyl)copper (I) into the ALD reaction chamber for 2 seconds to allow it to be selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 10 seconds to remove excess (trimethylsilanemethyl)copper(I) from the chamber. S5. Pulse-inject formic acid vapor into the ALD reaction chamber for 4 seconds to react with the adsorbed (trimethylsilanemethyl)copper(I), deposit a copper atom layer, and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 10 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 15 times. Finally, anneal the wafer at 250°C for 60 minutes under a nitrogen atmosphere to complete the repair.
[0023] Example 3 S1. Provide wafers from the same batch as in S1 of Example 1; S2. Place the wafer in the ALD reaction chamber, and set the temperature inside the chamber to 280°C and the pressure to 5 Torr. S3. Pulse-inject bis(hexafluoroacetylacetone)copper(II) into the ALD reaction chamber for 3 seconds to allow it to be selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove excess bis(hexafluoroacetylacetone)copper(II) from the chamber. S5. Pulse hydrogen gas into the ALD reaction chamber for 3 seconds to react with the adsorbed bis(hexafluoroacetylacetone)copper(II), deposit a copper atom layer, and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 40 times. Finally, anneal the wafer at 350°C for 45 minutes under a nitrogen atmosphere to complete the repair.
[0024] Example 4 S1. Provide wafers with a dielectric layer k-value < 2.5; S2. Place the wafer in the ALD reaction chamber, set the temperature inside the chamber to 120°C and the pressure to 0.5 Torr; S3. Pulse-inject bis(hexafluoroacetylacetone)copper(II) into the ALD reaction chamber for 3 seconds to allow it to be selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove excess bis(hexafluoroacetylacetone)copper(II) from the chamber. S5. Pulse hydrogen gas into the ALD reaction chamber for 3 seconds to react with the adsorbed bis(hexafluoroacetylacetone)copper(II), deposit a copper atom layer, and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 30 times. Finally, anneal the wafer at 180°C for 90 minutes under a nitrogen atmosphere to complete the repair.
[0025] Example 5 S1. Provide a wafer from the same batch as in S1 of Example 1; S2. Place the wafer in the ALD reaction chamber, set the temperature inside the chamber to 220°C and the pressure to 1.5 Torr. S3. Pulse-inject bis(hexafluoroacetylacetone)copper(II) into the ALD reaction chamber for 3 seconds to allow it to be selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 12 seconds to remove excess bis(hexafluoroacetylacetone)copper(II) from the chamber. S5. Pulsely introduce ethanol vapor into the ALD reaction chamber for 5 seconds to react with the adsorbed bis(hexafluoroacetylacetone)copper(II), deposit a copper atom layer, and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 12 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 25 times. Finally, anneal the wafer at 280°C for 40 minutes under a nitrogen atmosphere to complete the repair.
[0026] Example 6 S1. Provide a wafer from the same batch as in S1 of Example 1; S2. Place the wafer in the ALD reaction chamber, and set the temperature inside the chamber to 200°C and the pressure to 1 Torr. S3. Pulse-inject bis(hexafluoroacetylacetone)copper(II) into the ALD reaction chamber for 1 second, so that it is selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 8 seconds to remove excess bis(hexafluoroacetylacetone)copper(II) from the chamber. S5. Pulse hydrogen gas into the ALD reaction chamber for 1 second to react with the adsorbed bis(hexafluoroacetylacetone)copper(II), deposit a copper atom layer, and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 8 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 5 times. Finally, anneal the wafer at 200°C for 30 minutes under a nitrogen atmosphere to complete the repair.
[0027] Example 7 S1. Provide a 5nm technology node wafer with a via structure aspect ratio exceeding 10:1; S2. Place the wafer in the ALD reaction chamber, set the temperature inside the chamber to 150°C and the pressure to 0.2 Torr; S3. Pulse-inject bis(hexafluoroacetylacetone)copper(II) into the ALD reaction chamber for 8 seconds to allow it to be selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove excess bis(hexafluoroacetylacetone)copper(II) from the chamber. S5. Pulse hydrogen gas into the ALD reaction chamber for 8 seconds to react with the adsorbed bis(hexafluoroacetylacetone)copper(II), deposit a copper atom layer, and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 50 times. Finally, anneal the wafer at 250°C for 60 minutes under a nitrogen atmosphere to complete the repair.
[0028] Example 8 S1. Provide wafers from the same batch as in S1 of Example 1; S2. Place the wafer in the ALD reaction chamber, and set the temperature inside the chamber to 200°C and the pressure to 1 Torr. S3. Pulse-inject bis(hexafluoroacetylacetone)copper(II) into the ALD reaction chamber for 3 seconds to allow it to be selectively chemically adsorbed onto the exposed copper surface and the inner wall of the gap. S4. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove excess bis(hexafluoroacetylacetone)copper(II) from the chamber. S5. A mixture of hydrogen and formic acid vapor with a volume ratio of 1:1 is pulsed into the ALD reaction chamber and continuously introduced for 4 seconds, so that it reacts with the adsorbed bis(hexafluoroacetylacetone) copper(II) to deposit a copper atom layer and allow the atoms to diffuse into the gaps. S6. Continuously purge the ALD reaction chamber with nitrogen gas for 15 seconds to remove reaction byproducts. S7. Repeat the ALD cycle from S3 to S6 18 times. Finally, anneal the wafer at 300°C for 30 minutes under a nitrogen atmosphere to complete the repair.
[0029] Example 9 The repair process in this embodiment is the same as that in Embodiment 1, except that the annealing step is omitted.
[0030] Comparative Example 1 The repair process of this comparative example is the same as that of Example 1, except that the wafers produced in the same batch as in Example 1 are not subjected to ALD repair, but are directly annealed at 400°C for 60 minutes in a nitrogen atmosphere.
[0031] Comparative Example 2 The repair process of this comparative example is the same as that of Example 1, except that in step S3, bis(hexafluoroacetylacetone)copper(II) is replaced with copper acetylacetone.
[0032] The performance of the repaired wafers from Examples 1 to 9, Comparative Example 1 and Comparative Example 2 were tested respectively, and the test results are shown in Table 1.
[0033] Four equally spaced probes are used to contact the surface of a copper wire. A constant current is passed through the two outer probes, and the voltage is measured by the two inner probes. The resistance of the copper wire is then calculated using a formula. Apply current to a copper conductor and continuously increase the current density until failure, thus obtaining the maximum current density; The repaired wafer was rapidly cycled between -65°C and 150°C to test how many cycles it would take to fail. The thermal conductivity of the repaired wafer was measured using Raman spectroscopy. Table 1
[0034] According to the data in Table 1, the selective atomic layer repair process of the present invention, compared with the method without repair in Comparative Example 1, reduces the resistance by about 13%, increases the maximum current density by 150%, increases the thermal cycle life by 200%, and increases the thermal conductivity by 14%.
[0035] As can be seen, the selective atomic layer repair process of this invention, through the specific chemical reaction between a specific precursor material and the copper metal surface, combined with reduction and annealing treatments, can selectively deposit copper in pores and grain boundary gaps, eliminating voids and defects in the conductive cross-sectional area, increasing effective electron pathways, reducing resistance, and enabling it to withstand higher current densities without failure. The repaired, densified structure uniformly distributes stress, significantly improving resistance to thermomechanical fatigue and preventing crack formation and interface delamination. Furthermore, since unrepaired copper interconnects contain pores that impede heat flow, the repair process fills a thermal barrier layer, establishing a smoother phonon transport path, thereby improving thermal conductivity.
[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A repair process for selective atomic layers, characterized in that: Includes the following steps: The semiconductor structure is placed in the ALD reaction chamber. First, a first precursor is introduced and selectively adsorbed on the surface of the metal interconnect. Then, a second precursor is introduced and reacts with the first precursor adsorbed on the surface of the metal interconnect. The selective adsorption and reaction steps are repeated to obtain a metal atomic layer. The first precursor is selected from bis(hexafluoroacetylacetone)copper(II) or (trimethylsilanemethyl)copper(I); the second precursor is a reducing gas.
2. The repair process for selective atomic layers according to claim 1, characterized in that: The reducing gas is selected from at least one of hydrogen, formic acid, and ethanol.
3. The repair process for selective atomic layers according to claim 1, characterized in that: The temperature inside the ALD reaction chamber is 100~300℃ and the pressure is 0.1~10 Torr.
4. The repair process for selective atomic layers according to claim 1, characterized in that: The selective adsorption time is 1~5s; The reaction time is 1-5 seconds.
5. The repair process for selective atomic layers according to claim 1, characterized in that: After the selective adsorption and reaction are completed, inert gas is introduced for purging.
6. The repair process for selective atomic layers according to claim 1, characterized in that: The repeated selective adsorption and reaction steps are performed 2 to 50 times.
7. The repair process for selective atomic layers according to claim 1, characterized in that: After completing the repeated selective adsorption and reaction steps, the semiconductor structure is further subjected to annealing at a temperature of 150~400℃.