An aluminum post-corrosion product precise removal method and device based on wet pretreatment and atomic layer etching

Abstract

The present application relates to the field of semiconductor, especially to a kind of aluminum post-corrosion product precision removal method and equipment based on wet pretreatment and atomic layer etching, including detecting wafer after aluminum etching;60%~90% of large-area loose corrosion product is removed by wet pretreatment, wet pretreatment is 2.38%TMAH solution room temperature immersion 30~60s, rinsed with deionized water, IPA vapor drying;According to wafer pattern complexity, select P-ALE or hot ALE scheme, carry out 3~6 times etching cycle;O2 plasma is introduced to form passivation film, the present application is seamlessly integrated with existing semiconductor dry etching equipment, realizes digital precision control;Neutralize acidic residue in wet pretreatment, dry thoroughly, form dense passivation film after ALE, break the self-circulation corrosion chain from the source, avoid secondary corrosion and pattern collapse problem.

Description

Technical Field

[0001] This invention relates to the semiconductor field, and in particular to a method and apparatus for the precise removal of post-etching products from aluminum based on wet pretreatment and atomic layer etching. Background Technology

[0002] In semiconductor manufacturing, aluminum, as a classic metallic wiring material, is primarily etched using dry etching. However, this process is prone to post-etching corrosion, mainly due to secondary reactions between etching residues and moisture or cleaning agents. These reactions generate various corrosion products, including chlorides and hydrolysis products, fluorides, oxides and hydroxide derivatives, and polymer residues and derivatives. If these products are not completely removed, they can lead to increased resistivity of aluminum wiring, electromigration failure, short circuits, or open circuits, severely impacting the reliability and yield of semiconductor devices.

[0003] Existing methods for removing aluminum through post-etching are mainly wet processes, including TMAH immersion, SC1 cleaning, and dilute HF cleaning, supplemented by conventional dry etching auxiliary schemes. However, these methods have the following core drawbacks: 1. Incomplete removal: The wet process has insufficient penetration and is difficult to remove stubborn residual products in dead corners such as high aspect ratio structures, micro pits, and grain boundaries; 2. Uncontrollable substrate damage: During wet cleaning, aluminum substrates are prone to excessive dissolution, resulting in a thickness loss of 10-20 nm and potentially causing lattice damage. 3. Risk of secondary failure: Residual moisture and acid / alkali reagents after wet cleaning can easily cause secondary corrosion, forming a self-circulating corrosion chain; 4. Poor process adaptability: It cannot be compatible with the processing requirements of fine aluminum wiring and Al-TiN composite layer structure in advanced processes, and the surface tension can easily cause micro-patterns to collapse; 5. Difficulty in digital control: Wet processes are difficult to control precisely at the atomic level, resulting in poor stability of treatment effects.

[0004] Atomic layer etching (ALE) technology, with its modification-etching self-limiting cycle characteristics, has the ability to precisely control at the atomic level and can achieve three-dimensional selective etching without dead angles. However, when using ALE alone to treat the corrosion products of aluminum, a large number of cycles are required to remove the loose products over a large area, resulting in high process costs and low efficiency, making it difficult to meet the needs of mass production. Summary of the Invention

[0005] In view of the problems of incomplete removal, uncontrollable substrate damage, poor process adaptability, and difficulty in digital management in the above or existing technologies, this invention is proposed.

[0006] Therefore, the purpose of this invention is to provide a method for precise removal of post-corrosion products of aluminum based on wet pretreatment and atomic layer etching.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for precise removal of post-etching products of aluminum based on wet pretreatment and atomic layer etching, comprising S1: performing electron microscopy and energy dispersive X-ray spectroscopy on the aluminum etched wafer, and performing scanning electron microscopy and energy dispersive X-ray spectroscopy analysis on the aluminum etched semiconductor wafer to confirm the distribution state of the post-etching products, such as large-area loose products and local micro-residual products, as well as their type and wafer pattern complexity, so as to provide a basis for the selection of subsequent process parameters; S2: Wet pretreatment is used to remove 60%–90% of the large-area loose corrosion products. The wet pretreatment involves immersing in a 2.38% TMAH solution at room temperature for 30–60 seconds, followed by rinsing with deionized water and drying with IPA vapor. This method dissolves most of the loose corrosion products, generating soluble complexes that are then removed by rinsing; neutralizes acidic residues on the substrate surface, blocking the self-circulating corrosion chain; forms a thin passivation film on the aluminum substrate surface, preventing over-etching of the substrate in subsequent ALE processes; and thoroughly removes moisture to prevent residual moisture from entering the ALE vacuum chamber and combining with free radicals to cause secondary corrosion. S3: Depending on the complexity of the wafer pattern, either P-ALE or thermal ALE is selected, and 3–6 etching cycles are performed to remove stubborn residues and dead-angle products. S4: O2 plasma is introduced to form a passivation film.

[0008] As a preferred embodiment of the present invention's method for precise removal of post-etching products from aluminum based on wet pretreatment and atomic layer etching, the P-ALE scheme comprises the following parameters: O2 20 sccm + CH3 10 sccm, RF power 50W, processing time 20s, and low-energy Ar etching stage. + 50 eV, processing time of 20 s, and 10 s purging after each modification and etching.

[0009] As a preferred embodiment of the present invention, the method and equipment for precise removal of aluminum post-corrosion products based on wet pretreatment and atomic layer etching, wherein: the modification stage parameters of the thermal ALE scheme are TMA 5 sccm + H2O 10 sccm, the reaction temperature is 120℃, and the treatment time is 15s; the etching stage is HF 3 sccm + NH3 10 sccm, the reaction temperature is 120℃, and the treatment time is 20s; and the purging treatment time after each modification and etching is 15s.

[0010] As a preferred embodiment of the present invention, the method and equipment for precise removal of post-corrosion products of aluminum based on wet pretreatment and atomic layer etching, wherein: the order of wet pretreatment and ALE finishing cannot be reversed, and the wet pretreatment must be thoroughly dried by IPA vapor. This is to prevent the passivation film formed from being destroyed by the acid and alkali washing solution of the wet process, and the residual moisture in the wet process will cause secondary corrosion of the aluminum substrate. After the ALE finishing is completed, the drying must be carried out by isopropanol vapor drying to achieve complete dehydration.

[0011] As a preferred embodiment of the present invention, the method and equipment for precise removal of aluminum post-etching products based on wet pretreatment and atomic layer etching, wherein: the wafer pattern complexity includes ordinary patterns, fine patterns and Al-TiN composite layer structures; wafers with a linewidth greater than 1μm are set as ordinary patterns, and wafers with a linewidth less than 1μm are set as fine patterns; ordinary patterns use the P-ALE scheme, and fine patterns and Al-TiN composite layers use the thermal ALE scheme.

[0012] Based on the above-mentioned method for precise removal of aluminum post-etching products based on wet pretreatment and atomic layer etching, the present invention also provides a device for precise removal of aluminum post-etching products based on wet pretreatment and atomic layer etching, including a wafer picking unit, a nitrogen atmosphere manipulator disposed on one side of the wafer picking unit, and an etching product processing unit disposed on one side of the nitrogen atmosphere manipulator; the wafer picking unit is compatible with a front-opening wafer transfer box and is equipped with a wafer aligner; the etching product processing unit includes a housing disposed on one side of the nitrogen atmosphere manipulator, a wet processing component disposed on the housing, a vacuum manipulator disposed on the housing, a reaction component disposed on the housing, and an in-situ monitoring and control system disposed on the housing; The wet processing assembly includes a low-temperature plasma activation chamber, a TMAH treatment tank, a megasonic cleaning tank, and an IPA drying chamber, all connected sequentially via vacuum gate valves. The reaction assembly includes a P-ALE reaction chamber and a thermal ALE reaction chamber connected to a vacuum manipulator. The two chambers are isolated by a vacuum gate valve. The P-ALE reaction chamber is a capacitively coupled plasma structure equipped with CHF3, O2, and Ar gas paths. The thermal ALE reaction chamber is a hot-wall reactor with a heating temperature of 100–150°C, equipped with TMA, H2O, HF, and NH3 gas paths. The chamber material is nickel-plated aluminum alloy. The in-situ monitoring and control system includes a quadrupole mass spectrometer, an emission spectrometer, a machine vision system, and an AI process controller.

[0013] As a preferred embodiment of the present invention, the method and equipment for precise removal of aluminum post-corrosion products based on wet pretreatment and atomic layer etching, wherein: the P-ALE reaction chamber and the thermal ALE reaction chamber share a vacuum manipulator but the process areas are completely isolated.

[0014] As a preferred embodiment of the present invention, the method and equipment for precise removal of aluminum post-corrosion products based on wet pretreatment and atomic layer etching are wherein: the inner wall of the hot ALE reaction chamber is made of chemically plated nickel-aluminum alloy with a nickel layer thickness of 20-50 μm.

[0015] As a preferred embodiment of the present invention, a method and equipment for precise removal of aluminum post-corrosion products based on wet pretreatment and atomic layer etching is provided, wherein: a vacuum gate valve and a nitrogen curtain are provided for double isolation between the wet treatment component and the reaction component.

[0016] As a preferred embodiment of the present invention, the method and equipment for precise removal of aluminum post-corrosion products based on wet pretreatment and atomic layer etching, the AI ​​process controller automatically selects the P-ALE or thermal ALE scheme according to intelligent detection data, and dynamically adjusts the number of ALE cycles according to the feedback signal from the quadrupole mass spectrometer.

[0017] The beneficial effects of the present invention on the precise removal method and equipment for post-etching products of aluminum based on wet pretreatment and atomic layer etching are as follows: The present invention rapidly solves large-area porous products on wafers through wet pretreatment, and precisely solves stubborn residues and high aspect ratio structural dead corners through ALE finishing, achieving full-dimensional coverage removal with no residue; the wet process uses a low-damage TMAH solution, and ALE relies on its self-limiting etching characteristics. The synergistic effect of the two results in the total damage to the aluminum substrate being less than 5nm, far lower than that of SC1 or dilute solutions alone. The 10-20nm cleaning effectively protects the integrity and performance of aluminum wiring. The cost of wet processing for large-area products is only 1 / 10 of that of ALE. ALE only requires 3-6 cycles of fine finishing, avoiding the high cost of full ALE processing, making it suitable for mass production applications. It can be adapted to ordinary patterns, fine patterns, and Al-TiN composite layer structures, and can be seamlessly integrated with existing semiconductor dry etching equipment to achieve precise digital control. The wet pretreatment neutralizes acid residues and dries thoroughly, forming a dense passivation film after ALE, blocking the self-circulating corrosion chain from the source and avoiding secondary corrosion and pattern collapse problems. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the process flow for a precise removal method of post-etching products in aluminum based on wet pretreatment and atomic layer etching.

[0020] Figure 2 This is a schematic diagram of the operation process of an equipment for the precise removal of post-corrosion products of aluminum based on wet pretreatment and atomic layer etching.

[0021] Figure 3 This is a schematic diagram of the overall structure of an equipment for the precise removal of post-corrosion products of aluminum based on wet pretreatment and atomic layer etching.

[0022] Figure 4 This is a schematic diagram of the etching product processing unit in a precision removal equipment for post-etching products of aluminum based on wet pretreatment and atomic layer etching. Figure 1 .

[0023] Figure 5 This is a schematic diagram of the etching product processing unit in a precision removal equipment for post-etching products of aluminum based on wet pretreatment and atomic layer etching. Figure 2 .

[0024] In the diagram: 1. Wafer picking unit; 2. Nitrogen atmosphere manipulator; 3. Etching product processing unit; 31. Housing; 32. Wet processing assembly; 321. Low-temperature plasma activation chamber; 322. TMAH processing tank; 323. Megasonic cleaning tank; 324. IPA drying chamber; 33. Vacuum manipulator; 34. Reaction assembly; 341. P-ALE reaction chamber; 342. Thermal ALE reaction chamber; 35. In-situ monitoring and control system. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Example, refer to Figure 1 - Figure 5 This is an embodiment of the present invention, which provides a method and apparatus for precise removal of aluminum post-etching products based on wet pretreatment and atomic layer etching, comprising S1: performing electron microscopy and energy dispersive X-ray spectroscopy on the aluminum etched wafer; S2: Wet pretreatment is used to remove 60% to 90% of the large-area loose corrosion products. The wet pretreatment is to soak in 2.38% TMAH solution at room temperature for 30 to 60 seconds, followed by rinsing with deionized water and drying with IPA vapor. S3: Select either P-ALE or thermal ALE based on the complexity of the wafer pattern, and perform 3 to 6 etching cycles to remove stubborn residues and dead-angle products; S4: Introduce O2 plasma to form a passivation film.

[0027] The modification stage parameters for the P-ALE scheme are O2 20 sccm + CH3 10 sccm, RF power is 50W, processing time is 20s, and the etching stage is low-energy Ar. + 50 eV, processing time of 20 s, and 10 s purging after each modification and etching.

[0028] The modification stage parameters of the thermal ALE scheme are TMA 5 sccm + H2O 10 sccm, reaction temperature 120℃, and processing time 15s. The etching stage parameters are HF 3 sccm + NH3 10 sccm, reaction temperature 120℃, and processing time 20s. The purging time after each modification and etching is 15s.

[0029] The order of wet pretreatment and ALE finishing cannot be reversed, and the wet pretreatment must be thoroughly dried with IPA steam.

[0030] Among them, wafer pattern complexity includes ordinary patterns, fine patterns, and Al-TiN composite layer structures; Wafers with a linewidth greater than 1μm are set to normal pattern, and wafers with a linewidth less than 1μm are set to fine pattern; For ordinary patterns, the P-ALE scheme is used, while for fine patterns and Al-TiN composite layers, the thermal ALE scheme is used.

[0031] This embodiment also provides a precise removal device for aluminum post-etching products based on wet pretreatment and atomic layer etching, including a wafer picking unit 1, a nitrogen atmosphere manipulator 2 disposed on one side of the wafer picking unit 1, and an etching product processing unit 3 disposed on one side of the nitrogen atmosphere manipulator 2. The wafer fetching unit 1 is compatible with front-opening wafer transfer boxes and is equipped with a wafer aligner; The etching product processing unit 3 includes a housing 31 disposed on one side of the nitrogen atmosphere manipulator 2, a wet processing component 32 disposed on the housing 31, a vacuum manipulator 33 disposed on the housing 31, a reaction component 34 disposed on the housing 31, and an in-situ monitoring and control system 35 disposed on the housing 31. The wet processing assembly 32 includes a low-temperature plasma activation chamber 321, a TMAH treatment tank 322, a megasonic cleaning tank 323, and an IPA drying chamber 324, which are sequentially connected by a vacuum gate valve. The reaction assembly 34 includes a P-ALE reaction chamber 341 and a thermal ALE reaction chamber 342 connected to the vacuum manipulator 33. The two chambers are isolated by a vacuum gate valve. The P-ALE reaction chamber 341 is a capacitively coupled plasma structure and is equipped with CHF3, O2, and Ar gas paths. The thermal ALE reaction chamber 342 is a hot-wall reactor with a heating temperature of 100-150°C and is equipped with TMA, H2O, HF, and NH3 gas paths. The chamber material is nickel-plated aluminum alloy. The in-situ monitoring and control system 35 includes a quadrupole mass spectrometer, an emission spectrometer, a machine vision system, and an AI process controller, enabling real-time monitoring and closed-loop control of process parameters.

[0032] In this configuration, the P-ALE reaction chamber 341 and the thermal ALE reaction chamber 342 share the vacuum manipulator 33, but the process areas are completely isolated. This arrangement shortens the wafer transfer time between the two chambers.

[0033] The inner wall of the thermal ALE reaction chamber 342 is made of electroless nickel-aluminum alloy with a nickel layer thickness of 20-50 μm. This design allows the thermal ALE reaction chamber to withstand corrosion from HF and NH3 etching gases.

[0034] The wet processing component 32 and the reaction component 34 are equipped with a vacuum gate valve and a nitrogen curtain for double isolation. This arrangement prevents TMAH vapor from entering the ALE vacuum chamber.

[0035] The AI ​​process controller automatically selects either P-ALE or thermal ALE based on intelligent detection data, and dynamically adjusts the number of ALE cycles based on feedback signals from the quadrupole mass spectrometer. Wafers with ordinary patterns use the P-ALE scheme, while wafers with fine patterns and Al-TiN composite layer structures use the thermal ALE scheme.

[0036] In summary, the loading port receives the front-opening wafer transfer box and purges it with nitrogen. The atmospheric robot extracts the wafer, which is then sent to the optical inspection module for full wafer scanning after passing through the alignment device. This identifies the distribution of loose products and defects. The data is transmitted in real time to the AI ​​process controller, which determines the wafer type and plans the path: ordinary patterns are identified and enter the P-ALE cavity after wet processing; fine patterns and Al-TiN composite layer structures are identified and enter the thermal ALE cavity after wet processing.

[0037] At this point, under vacuum gate valve isolation, the wafer enters the low-temperature plasma activation chamber. After activation, the wafer is transferred to the TMAH processing tank and immersed in a 1.0%–2.38% TMAH solution at 15–25°C. The solution is circulated and filtered to maintain concentration fluctuations of less than ±0.05%. pH monitoring is used for automatic replenishment. The wafer is immersed for 20–45 seconds and then enters the megasonic cleaning tank. A 1MHz cavitation bubble is used in conjunction with a 300rpm rotation cleaning. The resistivity is monitored to determine the endpoint. Finally, the wafer passes through the IPA drying chamber, where it is dried using the Marangoni effect and vacuum-assisted drying. A dew point sensor confirms the endpoint, and the wafer is then isolated by the vacuum gate valve for further processing.

[0038] The vacuum robotic arm picks up the wafer and transfers it to the central transmission cavity. Helium mass spectrometry leak detection ensures that the leakage rate is up to standard, and the wafer is then distributed to the P-ALE or thermal ALE cavity according to instructions.

[0039] If the wafer has a standard pattern, it is then cooled to 20–50°C using an electrostatic chuck with helium back cooling. The wafer is then modified using 50W O2 20sccm and CHF 3 10sccm plasmas for 20 seconds. Finally, low-energy Ar plasma is used. +The wafer was etched at 50 eV for 20 s, with a 10 s purge after each modification and etching cycle, repeated 3-4 times. ALF3 was monitored using a quadrupole mass spectrometer. + and ALCL2 + The signal will terminate when it drops to a specified value.

[0040] If the wafer has a fine pattern and an Al-TiN composite layer structure, then heat the wafer to 120°C and then use TMA 5sccm+ The wafer was modified by processing at 10 sccm for 15 s, followed by etching at 10 sccm + NH3 for 20 s. This process was repeated 4–6 times, and ALF2 was monitored by quadrupole mass spectrometry. + Determine the endpoint.

[0041] After ALE is completed, apply 50 sccm of power in the original location at a power of 20-40W. Plasma oxidation lasts for 20–40 seconds to generate a dense AL2O3 film of 2–4 nm. After cooling to less than 50 °C in an N2 atmosphere, the vacuum robot transports the wafer to the unloading port via the central transfer cavity. Nitrogen gas breaks the vacuum, and the wafer returns to the front-opening wafer transfer box.

[0042] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for precise removal of post-etching products from aluminum based on wet pretreatment and atomic layer etching, characterized in that: Including S1: Electron microscopy and energy-dispersive X-ray spectroscopy for detecting aluminum-etched wafers; S2: Wet pretreatment is used to remove 60% to 90% of the large-area loose corrosion products. The wet pretreatment is to soak in 2.38% TMAH solution at room temperature for 30 to 60 seconds, followed by rinsing with deionized water and drying with IPA vapor. S3: Select either P-ALE or thermal ALE based on the wafer pattern complexity, and perform 3-6 etching cycles; the modification stage parameters for the P-ALE scheme are O2 20 sccm + CH3 10 sccm, RF power is 50W, processing time is 20s, and the etching stage uses low-energy Ar... + The processing time is 20s, with a 10s purge after each modification and etching step. The modification parameters for the thermal ALE process are: TMA 5sccm + H2O 10sccm, reaction temperature 120℃, processing time 15s; the etching parameters are: HF 3sccm + NH3 10sccm, reaction temperature 120℃, processing time 20s; and a 15s purge after each modification and etching step. The order of wet pretreatment and ALE finishing cannot be reversed, and the wet pretreatment must be thoroughly dried with IPA vapor. S4: Introduce O2 plasma to form a passivation film.

2. The method for precise removal of post-etching products of aluminum based on wet pretreatment and atomic layer etching as described in claim 1, characterized in that: Wafer pattern complexity includes ordinary patterns, fine patterns, and Al-TiN composite layer structures; Wafers with a linewidth greater than 1μm are set to normal pattern, and wafers with a linewidth less than 1μm are set to fine pattern; For ordinary patterns, the P-ALE scheme is used, while for fine patterns and Al-TiN composite layers, the thermal ALE scheme is used.

3. A device for precise removal of post-etching products of aluminum based on wet pretreatment and atomic layer etching, based on the method for precise removal of post-etching products of aluminum based on wet pretreatment and atomic layer etching as described in claim 2, characterized in that: It includes a wafer picking unit (1), a nitrogen atmosphere manipulator (2) disposed on one side of the wafer picking unit (1), and an etching product processing unit (3) disposed on one side of the nitrogen atmosphere manipulator (2). The wafer fetching unit (1) is compatible with front-opening wafer transfer boxes and is equipped with a wafer aligner; The etching product processing unit (3) includes a housing (31) disposed on one side of the nitrogen atmosphere manipulator (2), a wet processing component (32) disposed on the housing (31), a vacuum manipulator (33) disposed on the housing (31), a reaction component (34) disposed on the housing (31), and an in-situ monitoring and control system (35) disposed on the housing (31). The wet processing assembly (32) includes a low-temperature plasma activation chamber (321), a TMAH treatment tank (322), a megasonic cleaning tank (323), and an IPA drying chamber (324) that are sequentially connected by a vacuum gate valve. The reaction assembly (34) includes a P-ALE reaction chamber (341) and a thermal ALE reaction chamber (342) connected to a vacuum manipulator (33). The two chambers are isolated by a vacuum gate valve. The P-ALE reaction chamber (341) is a capacitively coupled plasma structure and is equipped with CHF3, O2, and Ar gas paths. The thermal ALE reaction chamber (342) is a hot-wall reactor with a heating temperature of 100-150°C and is equipped with TMA, H2O, HF, and NH3 gas paths. The chamber material is nickel-plated aluminum alloy. The in-situ monitoring and control system (35) includes a quadrupole mass spectrometer, an emission spectrometer, a machine vision system, and an AI process controller.

4. The precise removal equipment for aluminum post-corrosion products based on wet pretreatment and atomic layer etching as described in claim 3, characterized in that: The P-ALE reaction chamber (341) and the thermal ALE reaction chamber (342) share a vacuum manipulator (33), but the process areas are completely isolated.

5. The precise removal equipment for aluminum post-corrosion products based on wet pretreatment and atomic layer etching as described in claim 4, characterized in that: The inner wall of the thermal ALE reaction chamber (342) is made of chemically plated nickel-aluminum alloy with a nickel layer thickness of 20-50 μm.

6. The precise removal equipment for post-corrosion products of aluminum based on wet pretreatment and atomic layer etching as described in claim 5, characterized in that: A vacuum gate valve and a nitrogen curtain are provided for double isolation between the wet processing component (32) and the reaction component (34).

7. The precise removal equipment for aluminum post-corrosion products based on wet pretreatment and atomic layer etching as described in claim 6, characterized in that: The AI ​​process controller automatically selects either P-ALE or thermal ALE based on intelligent detection data, and dynamically adjusts the number of ALE cycles based on feedback signals from the quadrupole mass spectrometer.

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