Method for improving performance of ultra-low k film

Abstract

The invention provides a method for improving the performance of an ultra-low-k thin film, and the method comprises the steps: 1, providing a substrate, and forming the ultra-low-k thin film on the substrate; step 2, performing first extreme ultraviolet curing treatment on the ultra-low k thin film; and step 3, performing second extreme ultraviolet light curing treatment on the ultra-low k film, wherein the extreme ultraviolet light wavelength of the second extreme ultraviolet light curing treatment is greater than that of the first extreme ultraviolet light curing treatment. The processing step of extreme ultraviolet light curing is divided into two steps, the extreme ultraviolet light curing processing is carried out on the ultra-low-k thin film by adopting different specified wavelengths, the k value of the ultra-low-k thin film material is further reduced, meanwhile, the elasticity modulus of the ultra-low-k thin film material is improved, RC delay is improved, and therefore the operation speed of a device is increased.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for improving the performance of ultra-low-k thin films. Background Art

[0002] In the VLSI process, silicon dioxide, which has excellent thermal stability and moisture resistance, has always been the main insulating material used between metal interconnects. With the continuous reduction of integrated circuit technology nodes and the sharp increase in interconnection wiring density, the RC coupling parasitic effect caused by resistance and capacitance in the interconnection system has increased rapidly, affecting the speed of the device. Starting from the 45nm technology node, the industry began to use ultra-low-k thin film materials (such as BDII, i.e. porous silicon oxycarbide (porousSiOC)) as insulating materials between metal interconnects.

[0003] The formation of ultra-low-k thin film materials is mainly to introduce pore-forming agents into the reaction precursors. After the film growth is completed, the pore-forming agents in the film are removed by extreme ultraviolet light curing (UV curing), making it a porous material, thereby reducing its k value. At present, the process conditions for extreme ultraviolet light curing used for ultra-low-k films are: non-specified wavelength UV light, processing time 160s~220s. However, the process conditions of extreme ultraviolet light curing are difficult to further reduce the k value of ultra-low-k films without sacrificing mechanical properties (i.e., elastic modulus). Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a method for improving the performance of ultra-low-k films, so as to solve the problem in the prior art that extreme ultraviolet light curing is difficult to further reduce the k value of ultra-low-k films.

[0005] To achieve the above objectives and other related objectives, the present application provides a method for improving the performance of ultra-low-k thin films, comprising: Step 1, providing a substrate, and forming an ultra-low-k thin film on the substrate; Step 2, performing a first extreme ultraviolet light curing treatment on the ultra-low-k film; Step three, performing a second extreme ultraviolet light curing treatment on the ultra-low-k film, wherein the wavelength of the extreme ultraviolet light of the second extreme ultraviolet light curing treatment is greater than the wavelength of the extreme ultraviolet light of the first extreme ultraviolet light curing treatment.

[0006] Preferably, the wavelength of the extreme ultraviolet light in the first extreme ultraviolet light curing treatment is 180 nm, and the treatment time is 100 s.

[0007] Preferably, the wavelength of the extreme ultraviolet light in the second extreme ultraviolet light curing treatment is 220 nm, and the treatment time is 60s-120s.

[0008] Preferably, the ultra-low-k thin film is formed on the substrate by a chemical vapor deposition process.

[0009] Preferably, a pore former is introduced into the reaction precursor during the chemical vapor deposition process.

[0010] Preferably, the pore former comprises an organic pore former.

[0011] As described above, the method for improving the performance of ultra-low-k films provided in the present application has the following beneficial effects: the EUV curing process is divided into two steps, and the EUV curing process is performed on the ultra-low-k film using designated different wavelengths, thereby further reducing the k value of the ultra-low-k film material, while increasing its elastic modulus, improving RC delay, and thus increasing the computing speed of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 (a) shows the trend of dielectric constant and elastic modulus when the ultra-low-k film is cured by extreme ultraviolet light; Figure 1 (b) is a graph showing the change trend of film density under different EUV wavelengths when EUV curing is performed on an ultra-low-k film; Figure 1 (c) is a graph showing the changing trend of the elastic modulus of the ultra-low-k film at different EUV wavelengths when EUV curing is performed on the ultra-low-k film; Figure 2 A flow chart showing a method for improving the performance of ultra-low-k thin films provided in an embodiment of the present application. DETAILED DESCRIPTION

[0014] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0015] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0016] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0017] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0018] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0019] At present, the process conditions of extreme ultraviolet light curing used for ultra-low-k films are: non-specified wavelength UV light, processing time 160s~220s. However, the process conditions of extreme ultraviolet light curing are difficult to further reduce the k value of ultra-low-k films without sacrificing mechanical properties (i.e. elastic modulus).

[0020] Through experimental research, it is found that when the ultra-low-k film is cured by extreme ultraviolet light, without specifying the wavelength of the extreme ultraviolet light, as the processing time increases, the change trend of the dielectric constant (k value) and elastic modulus of the ultra-low-k film is as follows: Figure 1 As shown in (a), the k value of the ultra-low-k film gradually decreases, and after 100s, the k value begins to gradually increase; while the elastic modulus of the ultra-low-k film initially decreases and then gradually increases. Figure 1The elastic modulus data in (a) have been quantified, with the elastic modulus value of the film when the k value is 2.6 as the benchmark, that is, 1.0 in the right vertical axis.

[0021] like Figure 1 As shown in (b), when the wavelength of the extreme ultraviolet light is 180nm during extreme ultraviolet light curing, the residual amount of the pore-forming agent in the ultra-low-k film is the lowest, and the density (Intensity) is the lowest, that is, the porosity reaches a peak value.

[0022] like Figure 1 As shown in (c), when the wavelength of the EUV light is 220nm during EUV light curing, the elastic modulus of the ultra-low-k film is the largest.

[0023] Therefore, the present application provides a method for improving the performance of ultra-low-k films to solve the problem that the existing EUV curing process conditions are difficult to further reduce the k value of the ultra-low-k films.

[0024] See also Figure 2 , which shows a flow chart of a method for improving the performance of ultra-low-k thin films provided in an embodiment of the present application.

[0025] like Figure 2 As shown, the method for improving the performance of ultra-low-k thin films comprises the following steps: Step 1, providing a substrate, and forming an ultra-low-k thin film on the substrate; Step 2, performing a first extreme ultraviolet light curing treatment on the ultra-low-k film; Step three, performing a second extreme ultraviolet light curing treatment on the ultra-low-k film, wherein the wavelength of the extreme ultraviolet light of the second extreme ultraviolet light curing treatment is greater than the wavelength of the extreme ultraviolet light of the first extreme ultraviolet light curing treatment.

[0026] In step 1, optionally, the substrate is a silicon substrate, a germanium substrate, or a silicon-on-insulator substrate, etc.; or the material of the substrate may also include other materials, such as III-V compounds such as gallium arsenide. Those skilled in the art can select the constituent material of the substrate according to the type of device structure formed on the substrate, so the type of the substrate should not limit the protection scope of the present invention.

[0027] As an example, an ultra-low-k thin film is formed on a substrate by using a chemical vapor deposition process, and a pore former is introduced into a reaction precursor, and the pore former is preferably an organic pore former.

[0028] In step 2, as an example, the wavelength of the EUV light in the first EUV curing treatment is 180 nm, and the treatment time is 100 seconds. At this time, the ultra-low-k film has the lowest k value.

[0029] In step three, as an example, the wavelength of the extreme ultraviolet light for the second extreme ultraviolet light curing treatment is 220nm, and the treatment time is 60s-120s. At this time, the k value of the ultra-low-k film has not changed much compared to the end of step two, and the elastic modulus has increased significantly. If the treatment time of the second extreme ultraviolet light curing treatment is too long, the k value of the film will increase, and if it is too short, the elastic modulus of the film will not change much.

[0030] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present application in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0031] In summary, the method for improving the performance of ultra-low-k thin films provided by the present application splits the EUV curing process into two steps, using different wavelengths to perform EUV curing on the ultra-low-k thin film, further reducing the k value of the ultra-low-k thin film material, while increasing its elastic modulus, improving RC delay, and thus increasing the computing speed of the device. Therefore, the present application effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0032] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present application.

Claims

1. A method for improving the performance of ultra-low-k thin films, characterized in that: The method comprises: Step 1, providing a substrate, and forming an ultra-low-k thin film on the substrate; Step 2, performing a first extreme ultraviolet light curing treatment on the ultra-low-k film; Step 3, the ultra-low-k film is subjected to a second extreme ultraviolet light curing treatment, wherein the second extreme ultraviolet light curing treatment is The wavelength of the ultraviolet light is greater than the wavelength of the extreme ultraviolet light used in the first extreme ultraviolet light curing process.

2. The method according to claim 1, characterized in that The first extreme ultraviolet light curing process is an extreme ultraviolet light wave The length is 180nm and the processing time is 100s.

3. The method according to claim 1, characterized in that The second extreme ultraviolet light curing process is an extreme ultraviolet light wave The length is 220nm and the processing time is 60s-120s.

4. The method according to claim 1, characterized in that A chemical vapor deposition process is used to form a The ultra low k film.

5. The method according to claim 4, characterized in that When the chemical vapor deposition process is carried out, the reaction precursor Introducing pore-forming agents into the body.

6. The method according to claim 5, characterized in that The pore former includes an organic pore former.

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