A method of fabricating an interconnect structure
By utilizing laser activation and annealing techniques within the interconnect channels, the activated tungsten layer flows into the channels, solving the problem of voids or gaps in tungsten deposition, improving deposition quality, saving resources, and enhancing the performance of the interconnect structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUHAN CHUXING TECH CO LTD
- Filing Date
- 2022-12-27
- Publication Date
- 2026-07-31
AI Technical Summary
When tungsten is deposited in interconnect channels, it can easily lead to the filling of voids or gaps, affecting subsequent interconnect structure formation processes and reducing the performance of semiconductor structures.
After forming an initial tungsten layer in the interconnect channel, the initial tungsten layer is activated by laser irradiation and then annealed, so that the activated tungsten layer flows into the interconnect channel, thereby increasing the size of the channel opening and accelerating tungsten deposition.
This improved the quality of tungsten deposition, avoided waste of tungsten materials, saved resources, and enhanced the performance of interconnect structures.
Smart Images
Figure CN116013851B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and in particular to a method for fabricating an interconnect structure. Background Technology
[0002] Tungsten (W) has advantages such as low resistivity, strong resistance to electron migration and high melting point. Therefore, tungsten is widely used in interconnect structures (Contact or Via) in integrated circuits for metal interconnects.
[0003] However, when depositing tungsten in interconnect channels, the high aspect ratio of the interconnect channels can easily lead to filling voids or gaps, which in turn affects the subsequent interconnect structure formation process and reduces the performance of the final semiconductor structure.
[0004] Therefore, improving the deposition quality when depositing tungsten in interconnect channels is a technical problem that needs to be solved in this field. Summary of the Invention
[0005] In view of this, a summary section is provided to briefly introduce the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.
[0006] The purpose of this application is to provide a method for preparing an interconnect structure that can improve the deposition quality when depositing tungsten in the interconnect channel.
[0007] To achieve the above objectives, this application provides the following technical solution:
[0008] In a first aspect, embodiments of this application provide a method for fabricating an interconnect structure, comprising:
[0009] Provide substrate;
[0010] A dielectric layer is formed on the substrate;
[0011] Etching the dielectric layer forms interconnect channels that penetrate the dielectric layer;
[0012] An initial tungsten layer is formed within the interconnection channel;
[0013] The initial tungsten layer is activated by irradiating it with a laser to obtain an activated tungsten layer.
[0014] The activated tungsten layer is annealed to allow the activated tungsten layer at the opening of the interconnect channel to flow into the interconnect channel.
[0015] One possible implementation also includes:
[0016] A barrier layer is formed on the sidewalls and bottom of the interconnecting channel.
[0017] In one possible implementation, forming an initial tungsten layer within the interconnect channel includes:
[0018] An initial tungsten layer is deposited on the surface of the barrier layer.
[0019] In one possible implementation, after depositing an initial tungsten layer on the surface of the barrier layer and before irradiating the initial tungsten layer with a laser, the method further includes:
[0020] Hydrogen gas or hydrogen plasma is introduced into the reaction chamber where the substrate is placed, serving as a catalyst for activating the initial tungsten layer.
[0021] In one possible implementation, the deposition of the initial tungsten layer includes:
[0022] An initial tungsten seed layer was generated by reacting tungsten hexafluoride with silane.
[0023] Hydrogen gas or hydrogen plasma is introduced into the reaction chamber to remove fluorine impurities from the tungsten seed layer, thereby obtaining a treated tungsten seed layer.
[0024] A tungsten deposit layer is generated by reacting tungsten hexafluoride with hydrogen, and the treated tungsten seed layer and the tungsten deposit layer are used as the initial tungsten layer.
[0025] In one possible implementation, the frequency of the laser is greater than or equal to 3.846 × 10⁻⁶. 14 HZ, and less than or equal to 4.5 × 10 14 HZ.
[0026] In one possible implementation, the laser irradiation includes:
[0027] Irradiation is performed using laser pulses; the irradiation duration of a single laser pulse is greater than or equal to 0.1 s and less than or equal to 0.2 s.
[0028] In one possible implementation, annealing the activated tungsten layer includes:
[0029] The activated tungsten layer is annealed under an inert gas atmosphere.
[0030] In one possible implementation, the annealing temperature is greater than or equal to 300°C and less than or equal to 600°C.
[0031] In one possible implementation, the flow rate of the hydrogen gas or hydrogen plasma is greater than or equal to 500 sccm and less than or equal to 1000 sccm.
[0032] In one possible implementation, the barrier layer is made of titanium and titanium nitride.
[0033] Compared with the prior art, the embodiments of this application have the following beneficial effects:
[0034] This application provides a method for fabricating an interconnect structure. The method includes: providing a substrate; forming a dielectric layer on the substrate; etching the dielectric layer to form an interconnect channel penetrating the dielectric layer; forming an initial tungsten layer within the interconnect channel; irradiating the initial tungsten layer with a laser to activate the initial tungsten layer and obtain an activated tungsten layer; and annealing the activated tungsten layer to allow the activated tungsten layer at the opening of the interconnect channel to flow into the interconnect channel. In other words, this application uses laser activation to make the activated tungsten layer flowable, achieving the effects of increasing the size of the interconnect channel and accelerating tungsten deposition within the interconnect channel. The activated tungsten layer flows into the bottom of the interconnect channel, avoiding waste of tungsten material and saving resources. Attached Figure Description
[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0036] Figure 1 A flowchart illustrating a method for fabricating an interconnect structure according to an embodiment of this application is shown;
[0037] Figure 2 This illustration shows a cross-sectional schematic diagram of the structure during the fabrication process of an interconnect structure according to an embodiment of this application;
[0038] Figure 3 This illustration shows a cross-sectional schematic diagram of the structure during the fabrication process of another interconnect structure provided in this application embodiment;
[0039] Figure 4 A cross-sectional schematic diagram of the structure during the fabrication process of another interconnect structure provided in an embodiment of this application is shown;
[0040] Figure 5 A cross-sectional schematic diagram of the structure during the fabrication process of another interconnect structure provided in this application embodiment is shown;
[0041] Figure 6 A cross-sectional schematic diagram of the structure during the fabrication process of another interconnect structure provided in an embodiment of this application is shown;
[0042] Figure 7 This illustration shows a cross-sectional schematic diagram of the structure during the fabrication process of another interconnect structure provided in this application embodiment;
[0043] Figure 8 This paper illustrates a time-based diagram of each stage in the fabrication process of an interconnect structure according to an embodiment of this application.
[0044] Figure 9 A schematic diagram of an interconnection structure provided in an embodiment of this application is shown. Detailed Implementation
[0045] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.
[0046] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0047] As described in the background section, the applicant has discovered that tungsten (W) has advantages such as low resistivity, strong resistance to electron migration, and high melting point. Therefore, tungsten is widely used in interconnect structures (Contact or Via) in integrated circuits for metal interconnects.
[0048] Currently, tungsten chemical vapor deposition (CVD) mainly consists of three steps: soaking, nucleation, and bulk deposition. Soaking serves to wet the surface, while nucleation deposits a thin tungsten film on the substrate surface, which acts as a seed layer for subsequent bulk deposition.
[0049] However, when depositing tungsten in interconnect channels, the high aspect ratio of the interconnect channels can easily lead to filling voids or gaps, which in turn affects the subsequent interconnect structure formation process and reduces the performance of the final semiconductor structure.
[0050] Therefore, improving the deposition quality when depositing tungsten in interconnect channels is a technical problem that needs to be solved in this field.
[0051] To address the above technical problems, this application provides a method for fabricating an interconnect structure. The method includes: providing a substrate; forming a dielectric layer on the substrate; etching the dielectric layer to form an interconnect channel penetrating the dielectric layer; forming an initial tungsten layer within the interconnect channel; irradiating the initial tungsten layer with a laser to activate it and obtain an activated tungsten layer; and annealing the activated tungsten layer to allow the activated tungsten layer at the opening of the interconnect channel to flow into the interconnect channel. In other words, this application uses laser activation to make the activated tungsten layer flowable, achieving the effects of increasing the size of the interconnect channel opening and accelerating tungsten deposition within the interconnect channel. The activated tungsten layer flows into the bottom of the interconnect channel, avoiding waste of tungsten material and saving resources.
[0052] Exemplary methods
[0053] See Figure 1 The diagram shown is a flowchart of a method for fabricating an interconnect structure according to an embodiment of this application, including:
[0054] S101: Provides a substrate;
[0055] S102: A dielectric layer is formed on the substrate;
[0056] S103: Etching the dielectric layer to form interconnect channels penetrating the dielectric layer;
[0057] In the embodiments of this application, see Figure 2 The diagram shown is a cross-sectional view of the structure during the fabrication process of an interconnect structure according to an embodiment of this application. The substrate 1 can be a semiconductor substrate, such as a Si substrate, a Ge substrate, a SiGe substrate, SOI (Silicon On Insulator), or GOI (Germanium On Insulator). In other embodiments, the semiconductor substrate can also be a substrate including other elemental semiconductors or compound semiconductors, such as GaAs, InP, or SiC, and can also be a stacked structure, such as Si / SiGe, or other epitaxial structures, such as SGOI (Silicon Germanium On Insulator). In this embodiment, the substrate 1 is a bulk silicon substrate.
[0058] The dielectric layer 2 may be located on the substrate 1. The material of the dielectric layer 2 may include at least one of silicon oxide, silicon nitride and silicon oxynitride. Optionally, in this embodiment, the dielectric layer 2 is a silicon oxide layer.
[0059] For the formation of subsequent interconnect structures, see Figure 3The diagram shown is a cross-sectional view of another interconnect structure fabrication process provided in this application embodiment. In this application embodiment, the dielectric layer 2 can be etched to form an interconnect channel 3 that penetrates the dielectric layer. The interconnect channel 3 penetrates the dielectric layer 2 along the thickness direction to expose the upper surface of the substrate 1.
[0060] Optionally, the interconnect channel 3 may include interconnect vias or interconnect trenches. This application embodiment does not specifically limit the specific type of interconnect channel 3, but it can be set by those skilled in the art based on the shape of the actual interconnect structure.
[0061] S104: An initial tungsten layer is formed within the interconnect channel.
[0062] In this embodiment, an initial tungsten layer 4 can be formed in the interconnect channel 3 using a deposition process, so that the initial tungsten layer 4 can be used to prepare the interconnect structure in the future.
[0063] In one possible implementation, see Figure 4 The diagram shown is a cross-sectional view of another interconnect structure fabrication process provided in this application embodiment. A barrier layer 5 can be formed on the sidewall and bottom of the interconnect channel 3; an initial tungsten layer 4 is deposited on the surface of the barrier layer 5.
[0064] Specifically, a barrier layer 5 can be formed on the sidewalls and bottom of the interconnect channel 3 using physical vapor deposition (PVD), chemical vapor deposition (PVD), or atomic layer deposition (ALD) processes. The barrier layer 5 may only cover the sidewalls and bottom of the interconnect channel 3, or it may cover the upper surface of the dielectric layer 2, such as... Figure 4 As shown.
[0065] Optionally, the barrier layer 5 can be made of titanium and titanium nitride. Titanium acts as an adhesive and also has a certain gettingting effect. At high temperatures, it can react with SiO2 to generate Ti-containing silicon oxide, reducing resistance. Titanium alone is not sufficient because the chemical vapor deposition process used in tungsten deposition employs WF6. WF6 has strong oxidizing properties and will react with Ti to form a defect called a volcano, causing peeling of the entire interconnect structure from the substrate. An isolation layer is needed. Titanium nitride acts as an isolation layer, preventing the diffusion and contact of WF6 and Ti, thus avoiding the formation of volcano. TiN alone is also not sufficient because TiN has very high stress and is easily peeled from the substrate. Ti is needed as a buff layer to improve adhesion. Therefore, the barrier layer 5 can be made of a layer of titanium metal and a layer of titanium nitride metal.
[0066] Therefore, forming an initial tungsten layer 4 within the interconnect channel 3 in this embodiment may include depositing the initial tungsten layer 4 on the surface of the barrier layer 5.
[0067] In one possible implementation, see Figure 5 The diagram shown is a cross-sectional schematic of the structure during the fabrication process of another interconnect structure provided in this application embodiment. To facilitate subsequent large-scale tungsten deposition, a thin initial tungsten seed layer can first be deposited using atomic layer deposition (ALD) pulse nucleation. Specifically, the initial tungsten seed layer is generated by reacting tungsten hexafluoride with silane. The reaction rate is relatively slow, and the resulting initial tungsten seed layer is relatively uniform and flat, laying the foundation for subsequent large-scale tungsten deposition.
[0068] The reaction between tungsten hexafluoride and silane produces tungsten and other byproducts. Most of these byproducts are pumped away, but the highly corrosive fluoride ions remain partially in the tungsten film, reducing its purity and increasing its resistivity. Furthermore, fluoride ions can penetrate the underlying structure during subsequent large-scale tungsten deposition, affecting the structure of the formed device and, in severe cases, even causing open circuits.
[0069] Therefore, in response to this phenomenon of fluoride ion residue, the embodiments of this application can introduce hydrogen gas or hydrogen plasma into the reaction chamber to remove fluoride impurities in the tungsten seed layer, thereby obtaining a treated tungsten seed layer 41, the resistivity of which is less than that of the initial tungsten seed layer.
[0070] Then, see Figure 6The diagram shown is a cross-sectional schematic of the structure during the fabrication process of another interconnect structure provided in this application embodiment. A large-scale deposition of tungsten deposit layer 42 is initiated using a chemical vapor deposition process. Specifically, tungsten hexafluoride and hydrogen can be reacted to generate the tungsten deposit layer 42, with the treated tungsten seed layer 41 and the tungsten deposit layer 42 serving as the initial tungsten layer 4. The reaction between tungsten hexafluoride and hydrogen is relatively fast, which can improve the fabrication efficiency.
[0071] S105: Irradiate the initial tungsten layer with a laser to activate the initial tungsten layer and obtain an activated tungsten layer;
[0072] S106: Anneal the activated tungsten layer so that the activated tungsten layer at the opening of the interconnect channel flows into the interconnect channel.
[0073] In the embodiments of this application, see Figure 7 The diagram shown is a cross-sectional view of the structure during the fabrication process of another interconnect structure provided in this application embodiment.
[0074] To reduce the filling voids or gaps and improve the quality of deposited tungsten, the initial tungsten layer 4 can be irradiated with a laser to break the tungsten-tungsten metal bonds in the initial tungsten layer 4, thereby activating the initial tungsten layer 4 to obtain an activated tungsten layer 6; the activated tungsten layer 6 is then annealed so that the activated tungsten layer 6 at the opening of the interconnect channel 3 flows into the interconnect channel 3.
[0075] In other words, this application can activate the activated tungsten layer 6 to a flowable state through laser activation, thereby expanding the size of the opening of the interconnect channel 3 and accelerating the deposition of tungsten in the interconnect channel. The activated tungsten layer 6 flows into the bottom of the interconnect channel 3, avoiding the waste of tungsten material and saving resources.
[0076] Optionally, in this embodiment, the activated tungsten layer 6 can be annealed in an inert gas atmosphere to facilitate rapid annealing while preventing interference from impurities. The inert gas can be one or more of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe). This embodiment does not specifically limit the type of inert gas; however, those skilled in the art can determine the appropriate setting based on the actual situation.
[0077] Optionally, in the embodiments of this application, the annealing temperature is generally controlled at greater than or equal to 300°C and less than or equal to 600°C, which can both improve the reaction rate and avoid damage to the structure caused by excessive temperature.
[0078] In one possible implementation, after depositing the initial tungsten layer 4 on the surface of the barrier layer 5 and before irradiating the initial tungsten layer 4 with a laser, the embodiments of this application may further include:
[0079] Hydrogen gas or hydrogen plasma is introduced into the reaction chamber where substrate 1 is placed, serving as a catalyst for the initial tungsten layer activation. That is, in this embodiment, hydrogen gas or hydrogen plasma can be introduced to further promote the activation of the initial tungsten layer 4, improving efficiency and saving time.
[0080] Optionally, the flow rate of hydrogen or hydrogen plasma is greater than or equal to 500 sccm and less than or equal to 1000 sccm. This application embodiment does not specifically limit the flow rate, but it can be set by those skilled in the art according to the actual reaction rate.
[0081] In one possible implementation, when hydrogen plasma is introduced into the reaction chamber, a plasma generator can be added outside the reaction chamber to dissociate hydrogen gas (H2) and generate activated hydrogen ions (H+).
[0082] Simultaneously, a gas pipeline is added to connect the plasma generator and the reaction chamber, allowing the activated hydrogen ions (H+) to enter the chamber and react.
[0083] Furthermore, in this embodiment of the application, in order to avoid potential damage to the structure caused by laser irradiation, a low-frequency laser can be used for irradiation. The frequency of the laser can be greater than or equal to 3.846×10¹⁴ Hz and less than or equal to 4.5×10¹⁴ Hz.
[0084] Furthermore, depending on the thickness of the deposited tungsten, either a single laser irradiation or multiple laser irradiations can be used. See [link / reference needed]. Figure 8 The diagram shown illustrates the timeline of each stage in the fabrication process of the interconnect structure according to an embodiment of this application. When the thickness of the deposited tungsten is large, multiple laser irradiations and multiple inert atmosphere reflows can be performed. Furthermore, multiple low-energy irradiations can also prevent laser damage to the structure.
[0085] For example, laser pulses can be used for irradiation; the irradiation duration B of a single laser pulse is greater than or equal to 0.1S and less than or equal to 0.2S.
[0086] See Figure 9 The diagram shown is a schematic representation of an interconnection structure provided in an embodiment of this application. Figure 8 The interconnect channel 3 can be filled with interconnect structure by performing multiple laser irradiations and multiple inert atmosphere reflows.
[0087] This application provides a method for fabricating an interconnect structure. The method includes: providing a substrate; forming a dielectric layer on the substrate; etching the dielectric layer to form an interconnect channel penetrating the dielectric layer; forming an initial tungsten layer within the interconnect channel; irradiating the initial tungsten layer with a laser to activate the initial tungsten layer and obtain an activated tungsten layer; and annealing the activated tungsten layer to allow the activated tungsten layer at the opening of the interconnect channel to flow into the interconnect channel. In other words, this application uses laser activation to make the activated tungsten layer flowable, achieving the effects of increasing the size of the interconnect channel opening and accelerating tungsten deposition within the interconnect channel. The activated tungsten layer flows into the bottom of the interconnect channel, avoiding waste of tungsten material and saving resources.
[0088] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.
[0089] The above description is merely a preferred embodiment of this application. Although this application has disclosed preferred embodiments above, it is not intended to limit this application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall still fall within the protection scope of the technical solutions of this application.
Claims
1. A method for fabricating an interconnect structure, characterized in that, include: Provide substrate; A dielectric layer is formed on the substrate; Etching the dielectric layer forms interconnect channels that penetrate the dielectric layer; An initial tungsten layer is formed within the interconnection channel; The initial tungsten layer is irradiated with a laser to break the tungsten-tungsten metal bonds in the initial tungsten layer, thereby activating the initial tungsten layer to obtain an activated tungsten layer; After the initial tungsten layer is irradiated with a laser, the activated tungsten layer is annealed so that the activated tungsten layer at the opening of the interconnect channel flows into the interconnect channel; the annealing temperature is greater than or equal to 300°C and less than or equal to 600°C.
2. The method according to claim 1, characterized in that, Also includes: A barrier layer is formed on the sidewalls and bottom of the interconnecting channel.
3. The method according to claim 2, characterized in that, The formation of an initial tungsten layer within the interconnect channel includes: An initial tungsten layer is deposited on the surface of the barrier layer.
4. The method according to claim 3, characterized in that, After depositing an initial tungsten layer on the surface of the barrier layer and before irradiating the initial tungsten layer with a laser, the method further includes: Hydrogen gas or hydrogen plasma is introduced into the reaction chamber where the substrate is placed, serving as a catalyst for activating the initial tungsten layer.
5. The method according to claim 1, characterized in that, The formation of an initial tungsten layer within the interconnect channel includes: An initial tungsten seed layer was generated by reacting tungsten hexafluoride with silane. Hydrogen gas or hydrogen plasma is introduced into the reaction chamber to remove fluorine impurities from the tungsten seed layer, thereby obtaining a treated tungsten seed layer. A tungsten deposit layer is generated by reacting tungsten hexafluoride with hydrogen, and the treated tungsten seed layer and the tungsten deposit layer are used as the initial tungsten layer.
6. The method according to claim 1, characterized in that, The frequency of the laser is greater than or equal to 3.846 × 10⁻⁶. 14 HZ, and less than or equal to 4.5 × 10 14 HZ.
7. The method according to any one of claims 1-6, characterized in that, The laser irradiation includes: Irradiation is performed using laser pulses; the irradiation duration of a single laser pulse is greater than or equal to 0.1 s and less than or equal to 0.2 s.
8. The method according to any one of claims 1-6, characterized in that, The annealing of the activated tungsten layer includes: The activated tungsten layer is annealed under an inert gas atmosphere.
9. The method according to any one of claims 4-5, characterized in that, The flow rate of the hydrogen gas or hydrogen plasma is greater than or equal to 500 sccm and less than or equal to 1000 sccm.