A method for forming a low dielectric constant film

Abstract

The application provides a low dielectric constant film forming method, which is applied to the field of semiconductor technology. Specifically, in the low dielectric constant film forming method provided by the application, air or inert gas and other gases are fully blown into a silicon-containing precursor liquid source required for film formation in the form of micro-nano bubbles by using a micro-nano bubble generating device, so that a low dielectric constant film with a porous structure can be formed without using chemical pore-forming agents such as organic pore-forming agents; and in the low K film forming method provided by the application, micro-nano bubbles are introduced as pore-forming templates by blowing air in the film precursor liquid source, so that the porosity regulation difficulty of the formed low K film can be reduced while achieving the purposes of reducing the amount of chemicals used, reducing the process manufacturing cost and improving the process safety, and then the process steps and the tape-out cost are finally reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method for forming a low dielectric constant thin film. Background Technology

[0002] As the size of semiconductor integrated circuit transistors continues to shrink, circuit connections become increasingly dense, and the number of conductor connections in the circuit continues to increase. This leads to an increase in the resistive-capacitive delay (RC delay) between metal connections. However, since parasitic capacitance is positively correlated with the dielectric constant k of the insulating medium of the circuit layer, materials with low dielectric constant k are often introduced as the insulating medium for different circuit layers, i.e., low dielectric constant materials are used instead of traditional silicon dioxide.

[0003] Specifically, in existing technologies, the method for manufacturing low-k thin films in semiconductor integrated devices using low-dielectric-constant materials involves using a CVD (Continuous Chemical Vapor Deposition) machine to deposit a silicon source compound, such as DEMS, and an organic pore-forming agent, such as ATRP, into a low-k thin film through a film deposition and cross-linking reaction. The remaining pore-forming agent is then removed using ultraviolet light heating. Clearly, the use of organic pore-forming agents and the high electrical energy consumption of PECVD in existing technologies inevitably lead to high manufacturing costs, complex manufacturing systems, and stringent process requirements for low-k thin films. Summary of the Invention

[0004] The purpose of this invention is to provide a method for forming a low dielectric constant thin film with a porous structure, which introduces micro-nano bubbles by blowing air into a liquid source of the thin film precursor, replacing the existing technology of using organic pore-forming agents to manufacture low-k thin films with porous structures, thereby reducing the manufacturing cost of low dielectric constant thin films and simplifying the process steps.

[0005] To address the aforementioned technical problems, this invention provides a method for forming a low dielectric constant thin film, comprising the following steps:

[0006] A micro / nano bubble generator and a gas are provided. The micro / nano bubble generator is placed at the opening of a container containing a thin film precursor liquid source or immersed in the thin film precursor liquid source and the gas is introduced to form micro / nano bubbles.

[0007] The micro- and nano-bubbles are bubbled into a thin film precursor liquid source to form a bubble-rich liquid source containing the micro- and nano-bubbles, and a semiconductor substrate is provided.

[0008] The bubble-rich liquid source is spin-coated onto the surface of the semiconductor substrate using a spin coating process to form a bubble-rich liquid source film layer.

[0009] The bubble-rich liquid source film is subjected to ultraviolet thermal curing treatment to induce free radical crosslinking reaction, forming a porous low dielectric constant film.

[0010] Furthermore, the micro / nano bubble generating device may specifically include a micro / nano porous ceramic component with multiple nanopores.

[0011] Furthermore, the pore size range of the micro-nano porous ceramic component can be 30nm to 1000nm.

[0012] Furthermore, the gas may include at least one of air, nitrogen, argon, and helium.

[0013] Furthermore, the process conditions for blowing the micro-nano bubbles into the thin film precursor liquid source may include: the blowing pressure ranges from 70 kPa to 500 kPa, and the process duration can be from 30 min to 150 min.

[0014] Furthermore, the specific process conditions for the spin coating process may include: the rotation speed range is 1000 rpm to 4000 rpm.

[0015] Furthermore, the process conditions for ultraviolet thermal curing of the bubble-rich liquid source film layer may include: the wavelength range of the ultraviolet light source is 190nm to 600nm, and the irradiance range is 300mW / CM. 2 ~600mW / CM 2 The reaction temperature range is 200℃~400℃.

[0016] Furthermore, the thin film precursor liquid source can specifically be a silicon-rich organic liquid source, and the silicon-rich organic liquid source can specifically include an organosilicon nanocluster liquid source.

[0017] Furthermore, the solvent used in the organosilicon nanocluster liquid source can be at least one of tetrabutylammonium fluoride organic solvent, benzene organic solvent, and toluene organic solvent.

[0018] Furthermore, before forming the bubble-rich liquid source film layer using a spin coating process, the method for forming a low dielectric constant thin film provided by the present invention may further include the step of forming a buffer layer on the surface of the semiconductor substrate.

[0019] Compared with the prior art, the technical solution of the present invention has at least one of the following beneficial effects:

[0020] In the method for forming a low dielectric constant thin film provided by the present invention, a micro / nano bubble generating device is placed at the opening of a container containing a thin film precursor liquid source or immersed in the thin film precursor liquid source to convert a preset gas into micro / nano bubbles and fully bubble the bubbles into the thin film precursor liquid source. This achieves the purpose of forming a bubble-rich liquid source for manufacturing a porous low dielectric constant thin film without the use of chemical pore-forming agents such as organic pore-forming agents. Furthermore, since the method for forming a low dielectric constant thin film provided by the present invention introduces micro / nano bubbles as pore-forming templates by bubbling gas in the thin film precursor liquid source, it reduces the amount of chemicals used, lowers the manufacturing cost, and improves the process safety, while also reducing the difficulty of controlling the porosity of the formed low-k thin film, thereby ultimately reducing the number of process steps and the cost of wafer fabrication. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of a method for forming a low dielectric constant thin film according to an embodiment of the present invention;

[0022] Figure 2 Provided in one embodiment of the present invention Figure 1 A schematic diagram of the structure of the bubble-rich liquid source formed by the method for forming low dielectric constant thin films is shown.

[0023] Figure 3 This is a schematic diagram of the preparation process of a method for forming a low dielectric constant thin film according to an embodiment of the present invention;

[0024] The labels in the attached diagram are:

[0025] 100 - Bubble-rich liquid source; 13 - Gas pipeline;

[0026] 12-Micro / nano bubble generator (micro / nano porous ceramic component);

[0027] 200 - Semiconductor substrate; 210 - Buffer layer;

[0028] 220 - Bubble-rich liquid source membrane; Gas - Gas. Detailed Implementation

[0029] As described in the background section, in the prior art, the method for manufacturing low-k thin films in semiconductor integrated devices using low-dielectric-constant materials involves using a CVD (Chemical Vapor Deposition) machine to deposit a silicon source compound, such as DEMS, and an organic pore-forming agent, such as ATRP, into a low-k thin film through a film deposition and cross-linking reaction. The remaining pore-forming agent is then removed by ultraviolet light heating. Clearly, the use of organic pore-forming agents and the high electrical energy consumption required by PECVD in the prior art inevitably leads to high manufacturing costs, complex manufacturing systems, and stringent process requirements for low-k thin films.

[0030] To address this problem, the inventors of this invention propose using a micro / nano bubble generator placed at the opening of a container containing a thin film precursor liquid source or immersed in the liquid source. This device converts gases such as air, nitrogen, argon, or helium into micro / nano bubbles that meet the requirements of the porous, low-dielectric-constant thin film to be formed. These micro / nano bubbles are then bubbled into the thin film precursor liquid source used to form the low-dielectric-constant thin film. Finally, a thin film spin-coating and curing process is used to form a porous, low-dielectric-constant thin film that meets the design requirements.

[0031] Based on this, the purpose of the present invention is to provide a method for forming a low dielectric constant thin film with a porous structure, which introduces micro-nano bubbles by blowing air into a liquid source of the thin film precursor, replacing the prior art of using organic pore-forming agents to manufacture a porous low dielectric constant thin film, thereby achieving the purpose of reducing the manufacturing cost of the low dielectric constant thin film and simplifying the process steps.

[0032] The following is in conjunction with the appendix Figures 1-3 The method for forming a low dielectric constant thin film according to the present invention will be further described in detail below with specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may be practiced in other ways different from those described herein, and therefore the present invention is not limited to the specific embodiments disclosed below.

[0033] As shown in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. In detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views showing the device structure may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0034] For details, please refer to the following: Figure 1 and combined Figure 2 and Figure 3 , Figure 1 This is a schematic flowchart of a method for forming a low dielectric constant thin film according to an embodiment of the present invention. Figure 2 Provided in one embodiment of the present invention Figure 1 The diagram shows the structure of the bubble-rich liquid source formed by the method for forming low dielectric constant thin films. Figure 3 This is a schematic diagram of the process of forming a low dielectric constant thin film according to an embodiment of the present invention.

[0035] like Figure 1 As shown, the method for forming the low dielectric constant thin film may include the following steps:

[0036] Step S100: A micro / nano bubble generator and a gas are provided. The micro / nano bubble generator is placed at the opening of a container containing a thin film precursor liquid source or immersed in the thin film precursor liquid source and the gas is introduced to form micro / nano bubbles.

[0037] In this embodiment, a micro / nano bubble generating device can be provided first. For example, the micro / nano bubble generating device used in this invention can be a micro / nano porous ceramic component with multiple nanopores, such as... Figure 2As shown in Figure 12, the pore size range of each nanopore in the micro / nanoporous ceramic component with multiple nanopores can be 30 nm to 1000 nm, specifically 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, and any two of the above values, such as 30 nm to 100 nm, 100 nm to 400 nm, and 400 nm to 1000 nm. Then, a certain amount of gas (Gas) for forming bubbles is introduced into the micro / nanobubble generator 12 (micro / nanoporous ceramic component), and micro / nanobubbles with the same pore size range as specified by the micro / nanobubble generator are diffused from it. For example, the gas used in this invention may specifically be at least one of air, nitrogen, argon and helium.

[0038] It is understood that in other embodiments, the diameters of the micro / nano bubble generating device, the gas Gas, and the formed micro / nano bubbles can be adjusted according to the required dielectric constant (K) of the low dielectric constant film to be formed and the pore size of the porous structure of the low dielectric constant film. This invention will not specifically limit or describe these details. Furthermore, the... Figure 2 The positional relationship between the micro / nano bubble generator, the gas used to form the micro / nano bubbles, and the container containing the liquid source of the thin film precursor is shown in a simple way.

[0039] Step S200, as follows Figure 2 As shown, the micro-nano bubbles are bubbled into a thin film precursor liquid source to form a bubble-rich liquid source 100 containing the micro-nano bubbles, and a semiconductor substrate is provided.

[0040] In this embodiment, after forming micro / nano bubbles that meet the design requirements using the above-described step S100, they can be transported through a gas pipeline, such as... Figure 2 As shown in step 13, the formed micro-nano bubbles are blown into a container containing a reactive silicon source precursor liquid source for the subsequent step S300 to form a bubble-rich liquid source film by a certain blowing pressure and duration. The reactive silicon source precursor liquid source is the same as the film precursor liquid source, dissolving the micro-nano bubbles into the film precursor liquid source to form a film-rich liquid source. Figure 2The bubble-rich liquid source 100 shown contains the aforementioned micro-nano bubbles. For example, the inflation pressure of the micro-nano bubbles being blown into the liquid source of the film precursor can be in the range of 70 kPa to 500 kPa, that is, it can be 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 100 kPa, 150 kPa, 200 kPa, 250 kPa, 300 kPa, 350 kPa, 400 kPa, 450 kPa, 500 kPa and any two of the above numbers; and the duration of blowing the micro-nano bubbles into the liquid source of the film precursor can be 30 min to 150 min, that is, specifically 30 min, 35 min, 40 min, 45 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 145 min, 150 min and any two of the above numbers.

[0041] Furthermore, the reactive silicon precursor liquid source (i.e., the thin film precursor liquid source) can be, for example, a silicon-rich organic liquid source containing organosilicon nanoclusters BuPSi with tert-butyl substituents; exemplary, in the embodiments of the present invention, the solvent used in the thin film precursor liquid source can be at least one of tetrabutylammonium fluoride organic solvent THF, benzene organic solvent, or toluene organic solvent with a certain viscosity. At the same time, it can also be a mixed organic solution with a certain viscosity composed of at least two of the organic solutions, so as to maintain the stability of the micro-nano bubbles dissolved in the bubble-rich liquid source by utilizing the viscosity of the solution.

[0042] After that, as Figure 3 As shown, a semiconductor substrate 200 is further provided as a carrier for forming the low dielectric constant thin film of the porous structure in subsequent steps. Exemplarily, the semiconductor substrate 200 provided by this invention can be any suitable substrate known in the art, such as at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors, and also includes multilayer structures composed of these semiconductors.

[0043] It should be noted that, in the embodiments provided by the present invention, the following... Figure 2The micro / nano bubble generator 12 shown can be placed at the opening of a container containing a thin film precursor liquid source, or it can be directly immersed in the thin film precursor liquid source in the container. Then, by adjusting the energy parameters of the bubbles discharged from the micro / nano bubble generator 12, a certain amount of gas gas is converted into micro / nano bubbles (not shown). After that, the formed micro / nano bubbles are fully blown into the thin film precursor liquid source.

[0044] Step S300, see below. Figure 3 The bubble-rich liquid source is spin-coated onto the surface of the semiconductor substrate 200 using a spin-coating process to form a bubble-rich liquid source film layer 220.

[0045] In this embodiment, a buffer layer 210 can first be formed on the surface of the semiconductor substrate 200 provided in step S200 using deposition processes such as chemical vapor deposition or physical vapor deposition. Then, a bubble-rich liquid source film layer 220 of a preset thickness is formed on the surface of the buffer layer 210 using a spin coating process at a preset rotation speed. The material of the buffer layer can be silicon dioxide, silicon nitride, etc., and the rotation speed of the spin coating process can be in the range of 1000 rpm to 4000 rpm, specifically 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, and any two of the above numbers.

[0046] As can be seen from the above steps S100 to S300, in the method for forming a low dielectric constant thin film provided by the present invention, a micro-nano bubble generating device placed in the liquid source of the thin film precursor is used to convert the preset gas into micro-nano bubbles, and fully bubbling the micro-nano bubbles into the liquid source of the thin film precursor. This achieves the purpose of forming a bubble-rich liquid source for manufacturing a porous low dielectric constant thin film without the use of chemical pore-forming agents such as organic pore-forming agents. Therefore, while reducing the amount of chemicals used, reducing the manufacturing cost, and improving the safety of the process, the porosity control difficulty of the formed low-k thin film is reduced, thereby ultimately reducing the number of process steps and the cost of wafer fabrication.

[0047] In step S400, the bubble-rich liquid source film layer 220 is subjected to ultraviolet thermal curing treatment to allow the bubble-rich liquid source film layer to undergo free radical cross-linking reaction, forming a porous low dielectric constant film.

[0048] In this embodiment, after forming the rich-bubble liquid source film layer, the semiconductor substrate with the formed rich-bubble liquid source film layer needs to be subjected to ultraviolet thermal curing treatment under ultraviolet light irradiation and a thermal environment, so that the precursor liquid source around the micro-nano bubbles dissolved in the rich-bubble liquid source film layer, for example, the silicon-rich organic matter of the organosilicon nanocluster BuPSi with tert-butyl substituents, undergoes a free radical crosslinking reaction, thereby forming a relatively stable low dielectric constant thin film with a porous structure that is crosslinked and bonded to form a network structure. Among them, the process conditions for the ultraviolet thermal curing treatment of the rich-bubble liquid source film layer include: the wavelength, light irradiance, and reaction temperature of the ultraviolet light source; among them, the wavelength of the ultraviolet light source can be 190nm to 600nm, that is, specifically, it can be 190nm, 200nm, 210nm, 220nm, 250nm, 300nm, 400nm, 500nm, 600nm, etc.; and the light irradiance can be 300mW / CM 2 ~600mW / CM 2 That is, 300mW / CM 2 、350mW / CM 2 、400mW / CM 2 、450mW / CM 2 、500mW / CM 2 、550mW / CM 2 、600mW / CM 2 The reaction temperature is 200°C to 400°C, that is, 200°C, 300°C, 400°C.

[0049] According to the above steps, it can be seen that the forming method provided by the present invention can specifically control the process conditions of the ultraviolet thermal curing treatment, that is, the light wavelength, light irradiance, thermal environment temperature, etc., so that in a relatively stable silicon-rich organic liquid source, around the micro-nano bubbles stabilized in the silicon-rich organic liquid source, the precursor liquid source around it undergoes a crosslinking reaction, and finally a low dielectric constant thin film with a porous structure is formed.

[0050] Furthermore, using the method provided by the present invention, the value range of the dielectric constant K of the low dielectric constant thin film with a porous structure is: 1 < K < 3, that is, K can specifically be equal to 1.1, 1.2, 1.3, 1.4, 1.5, 2, 2.1, 2.2, 2.5, 2.6, 2.7, 2.8, 2.9, 3, etc.

[0051] In summary, the method for forming a low dielectric constant thin film provided by this invention utilizes a micro / nano bubble generator placed at the opening of a container containing a thin film precursor liquid source or immersed in the liquid source. This generator converts a pre-set gas into micro / nano bubbles and fully bubbles them into the liquid source, thereby achieving the goal of forming a bubble-rich liquid source for manufacturing a porous low dielectric constant thin film without the use of organic pore-forming agents or other chemical pore-forming agents. Furthermore, since the method for forming a low dielectric constant thin film provided by this invention introduces micro / nano bubbles as pore-forming templates by bubbling gas into the thin film precursor liquid source, it reduces the amount of chemicals used, lowers manufacturing costs, and improves process safety. Simultaneously, it reduces the difficulty of controlling the porosity of the formed low-k thin film, ultimately reducing process steps and wafer fabrication costs.

[0052] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0053] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the embodiments of apparatus, electronic devices, and computer-readable storage media are basically similar to the method embodiments, and therefore the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for forming a low dielectric constant thin film, characterized in that, Includes the following steps: A micro / nano bubble generator and a gas are provided. The micro / nano bubble generator is placed at the opening of a container containing a thin film precursor liquid source or immersed in the thin film precursor liquid source and the gas is introduced to form micro / nano bubbles. The micro-nano bubbles are bubbled into a thin film precursor liquid source to form a bubble-rich liquid source containing the micro-nano bubbles, and a semiconductor substrate is provided. The bubble-rich liquid source is spin-coated onto the surface of the semiconductor substrate using a spin coating process to form a bubble-rich liquid source film layer. The bubble-rich liquid source film is subjected to ultraviolet light thermocuring treatment to enable the bubble-rich liquid source film to undergo free radical cross-linking reaction, forming a porous low dielectric constant film. The micro-nano bubble generating device includes a micro-nano porous ceramic component with multiple nanopores, the pore size of which is 30nm to 1000nm; the thin film precursor liquid source includes a silicon-rich organic liquid source, which includes an organosilicon nanocluster liquid source. The solvent used in the organosilicon nanocluster liquid source is at least one of tetrabutylammonium fluoride organic solvent, benzene organic solvent, and toluene organic solvent; Before forming the bubble-rich liquid source film layer using a spin coating process, the formation method further includes forming a buffer layer on the surface of the semiconductor substrate.

2. The method for forming a low dielectric constant thin film as described in claim 1, characterized in that, The gas includes at least one of air, nitrogen, argon, and helium.

3. The method for forming a low dielectric constant thin film as described in claim 2, characterized in that, The process conditions for blowing the micro-nano bubbles into the thin film precursor liquid source include: the blowing pressure is 70 kPa to 500 kPa, and the process duration is 30 min to 150 min.

4. The method for forming a low dielectric constant thin film as described in claim 1, characterized in that, The process conditions for the spin coating process include: a rotation speed of 1000 rpm to 4000 rpm.

5. The method for forming a low dielectric constant thin film as described in claim 1, characterized in that, The process conditions for ultraviolet light thermocuring of the bubble-rich liquid source film include: the wavelength of the ultraviolet light source is 190nm~600nm, and the irradiance is 300mW / CM. 2 ~600mW / CM 2 The reaction temperature is 200℃~400℃.

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