Physical unclonable function and manufacturing method thereof
By forming a semiconductor film with an atomic step morphology on a substrate and depositing a metal film, and using dark-field microscopy to identify features, the problem of easily replicable physically unclonable functions in the prior art has been solved, realizing physically unclonable functions with high security and difficulty in cloning.
Patent Information
- Application Number
- CN202510957827.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-10-28
AI Technical Summary
In the existing technology, physically unclonable functions have become relatively easy to copy during the manufacturing process due to the advancement of high-resolution testing technology and high-precision manufacturing processes, making it difficult to ensure their security and the difficulty of copying.
By forming a semiconductor film with atomic step morphology resolvable by atomic force microscopy on a substrate and depositing a metal film on it, the physical non-cloning function is realized by utilizing the randomly formed disordered step surface morphology during the semiconductor film growth process and combining it with feature extraction under dark field conditions using conventional microscopy.
It improves the randomness encoding capacity of physically unclonable functions, enhances their resistance to nanoscale physical cloning attacks, ensures high security and a simple reading and identification process, and reduces false acceptance and rejection rates.
Smart Images
Figure CN120850367A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, specifically to a physically unclonable function and its fabrication method. Background Technology
[0002] Physically unclonable functions (PUFs) are physical "fingerprints" that are difficult to clone, generated by the inherent microscopic random physical characteristics of the manufacturing process. They have great application value in information security fields such as identity authentication, chip anti-counterfeiting, communication encryption, and blockchain.
[0003] Although PUFs are extremely difficult to replicate due to the enormous microscopic randomness in the manufacturing process, with the continuous advancement of manufacturing technology, it has gradually become possible to replicate a PUF with similar disordered feature structures and response characteristics at the hundred-nanometer scale by using high-resolution testing technology and high-precision manufacturing processes, along with sufficient time investment. Summary of the Invention
[0004] In view of this, the technical problem to be solved by the present invention is to provide a physically unclonable function and a method for making the same. The physically unclonable function provided in this application is difficult to physically replicate and clone, and the preparation method is simple.
[0005] This application provides a physically unclonable function, including:
[0006] Substrate;
[0007] A semiconductor film is formed on the substrate, the surface of which has an atomic step morphology that can be resolved by an atomic force microscope;
[0008] A metal film formed on the semiconductor film.
[0009] In some specific implementations, the vertical thickness of each step of the atomic step is independently 0.1 nm to 50 nm;
[0010] The width of each atomic step is independently no greater than 50 μm.
[0011] In some specific implementations, the width of each atomic step is independently 0.01 μm to 20 μm.
[0012] In some specific implementations, growth structure points are also formed on the surface of the semiconductor film.
[0013] In some specific implementations, the growth structure point is one or more of GaN hexagonal prisms, AlN hexagonal prisms, AlGaN hexagonal prisms, or Si depressions.
[0014] In some specific implementations, the thickness of the semiconductor film is 0.5 μm to 10 μm;
[0015] The semiconductor film is selected from one or more stacked films of Si film, SiC film, AlN film, GaN film, AlGaN film and BN film.
[0016] In some specific implementations, the metal film is selected from one or more of Au film, Al film, Cu film, Ag film, Ti film, Cr film and Ni film;
[0017] The thickness of the metal film is 10 nm to 500 nm.
[0018] In some specific implementations, the substrate is selected from Si wafers, SiC wafers, sapphire, glass wafers, or GaN-based substrates;
[0019] The thickness of the substrate is 100μm to 1000μm.
[0020] This application also provides a method for creating a physically unclonable function, including:
[0021] A semiconductor film with an atomic step morphology resolvable by an atomic force microscope is formed on a substrate;
[0022] A metal film is formed on the semiconductor film.
[0023] In some specific implementations, semiconductor films are formed on a substrate using metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).
[0024] The physically unclonable function provided in this application includes: a substrate; a semiconductor film formed on the substrate, the surface of which has an atomic step morphology resolvable by atomic force microscopy; and a metal film formed on the semiconductor film. This application uses the randomly formed disordered step surface morphology during the growth of the semiconductor film as the optical physically unclonable function. After depositing a metal film on the surface of the semiconductor film, this atomically high level of surface randomness can be obtained under a conventional microscope in a dark field, thereby achieving anti-counterfeiting and traceability characteristics. The physically unclonable function provided in this application has advantages such as simple preparation, high randomness encoding capacity, difficulty in physical replication and cloning, invisibility under bright fields, simple reading and identification, and low false acceptance and false rejection rates. Moreover, the physically unclonable function provided in this application can resist nanoscale physical cloning attacks, resulting in higher security. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the structure of a physically unclonable function provided in an embodiment of this application;
[0026] Figure 2AFM image of the AlGaN thin film prepared in Example 1 of this application;
[0027] Figure 3 A photograph of a physically unclonable function under a bright field optical microscope, provided as an embodiment of this application;
[0028] Figure 4 An image of a physically unclonable function under a dark field optical microscope, provided for an embodiment of this application;
[0029] Figure 5 AFM images of physically unclonable functions prepared for embodiments of this application;
[0030] Figure 6 The PUF test provides the intra- and inter-film distances of Hamming films under dark field conditions in the embodiments of this application. Detailed Implementation
[0031] This invention discloses a physically unclonable function and its fabrication method. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the function. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.
[0032] This application provides a physically unclonable function, including:
[0033] Substrate;
[0034] A semiconductor film is formed on the substrate, the surface of which has an atomic step morphology that can be resolved by an atomic force microscope;
[0035] A metal film formed on the semiconductor film.
[0036] See Figure 1 , Figure 1 This is a schematic diagram of the structure of a physically unclonable function provided in an embodiment of this application, wherein 10 is a substrate, 20 is a semiconductor film, 201 is an atomic step, and 202 is a structural point.
[0037] The physically unclonable function provided in this application includes a substrate 10, which provides support for semiconductor films and metal films. In some specific implementations, the substrate is selected from Si wafers, SiC wafers, sapphire, glass wafers, or GaN-based substrates, preferably sapphire. In some specific implementations, the thickness of the substrate is 100 μm to 1000 μm, preferably 150 μm to 800 μm, and more preferably 200 μm to 600 μm. In some specific implementations, the substrate can be a patterned substrate.
[0038] The physically unclonable function provided in this application includes a semiconductor film 20 formed on a substrate 10, the surface of which has an atomic force microscopy (AFM) morphology of atomic steps. Those skilled in the art will understand that an atomic step is a staircase-like structure formed by atoms. In some specific implementations, the vertical thickness of each step of the atomic step is independently 1 to 100 atomic levels, preferably 2 to 80 atomic levels, more preferably 5 to 50 atomic levels. Alternatively, the vertical thickness of each step of the atomic step can be considered to be independently 0.1 nm to 50 nm, preferably 0.1 nm to 40 nm, more preferably 0.1 nm to 30 nm. Those skilled in the art will understand that the vertical thickness of the step described in this application refers to the height of the step. In some specific implementations, the width of each step of the atomic step is independently not greater than 50 μm, preferably 0.01 μm to 20 μm, more preferably 0.1 μm to 15 μm, and most preferably 0.3 μm to 10 μm. Those skilled in the art will understand that the width of the step described in this application refers to the maximum width of the step. This application does not impose any special limitation on the number of steps in the atomic steps; the number can be determined based on the size of the substrate, the height of the steps, and the width of the steps.
[0039] In some specific implementations, the atomic steps can include a multi-level structure. Specifically, the atomic steps include multiple first-level steps with larger dimensions, such as greater vertical thickness or wider width. Multiple second-level steps with slightly smaller dimensions can be distributed on any one or more first-level steps to form a second-level step structure. This multi-level structure increases the randomness coding capacity and further improves security.
[0040] In some specific implementations, growth structure points, such as hexagonal prisms or recesses, are also formed on the surface of the semiconductor film, including but not limited to GaN hexagonal prisms, AlN hexagonal prisms, AlGaN hexagonal prisms, Si recesses, etc., which can serve as auxiliary identification feature points.
[0041] In some specific implementations, the semiconductor film is a semiconductor film formed of group I to V compounds, including but not limited to Si films, SiC films, AlN films, GaN films, AlGaN films, and BN films, etc., and can be a single layer or a multilayer stacked film. In some specific implementations, the thickness of the semiconductor film is 0.5 μm to 10 μm, preferably 0.8 μm to 8 μm, and more preferably 1 μm to 5 μm.
[0042] Random features such as atomic steps and structural points are difficult to identify under conventional microscopes. The role of the metal film formed on the surface of the semiconductor film is to enable the surface morphology (including atomic steps and structural points) to be resolved and extracted by conventional optical microscopes, thus serving as a fingerprint for dark-field encrypted PUF identification. In some specific implementations, the metal film includes, but is not limited to, Au films, Al films, Cu films, Ag films, Ti films, Cr films, or Ni films, and can be one or more of these. In some specific implementations, the thickness of the metal film is 10 nm to 500 nm, preferably 20 nm to 450 nm, and more preferably 50 nm to 400 nm.
[0043] This application also provides a method for creating a physically unclonable function, including:
[0044] A semiconductor film with an atomic step morphology resolvable by an atomic force microscope is formed on a substrate;
[0045] A metal film is formed on the semiconductor film.
[0046] In some specific implementations, semiconductor films are formed on a substrate using metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).
[0047] This application first uses methods such as metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) to form a semiconductor film with an atomic step morphology that can be resolved by atomic force microscopy on a substrate. This application does not have any special restrictions on the specific parameters of MOCVD or MBE, and can select them according to the conventional methods of those skilled in the art.
[0048] After forming a semiconductor film, its surface can randomly form a semiconductor film with an atomic step morphology resolvable by an atomic force microscope. Then, a metal film is formed on the surface of the semiconductor film. This application does not have any special limitations on the method for forming the metal film, and it can be electroplating, electroless plating, electron beam evaporation, magnetron sputtering, etc. This application does not have any special limitations on the specific parameters of the electroplating, electroless plating, electron beam evaporation, and magnetron sputtering, and they can be selected according to the methods conventionally used by those skilled in the art.
[0049] The surface morphology information of the PUF provided in this application is a random and disordered surface morphology formed during the growth of the semiconductor film. It has a high randomness encoding capacity, is difficult to physically replicate and clone, and can resist nanoscale physical cloning attacks, thus possessing high security. Furthermore, the surface morphology information of the PUF provided in this application is difficult to obtain under bright fields using conventional optical microscopes, but can be obtained under dark fields, making it convenient to use.
[0050] The present invention will be further described below with reference to the embodiments.
[0051] Example 1
[0052] A 100 nm thick AlGaN film was grown on a 500 μm thick patterned sapphire substrate using molecular beam epitaxy (MBE). The specific process parameters were as follows: using a sapphire substrate, the AlGaN film was grown by MBE at 700℃~750℃, and the growth rate was 0.1 nm / s~0.2 nm / s.
[0053] The AlGaN thin film was tested using atomic force microscopy (AFM), and the results are as follows: Figure 2 As shown, Figure 2 The above are AFM images of the AlGaN thin film prepared in Example 1 of this application. Figure 2 It is known that the surface of the AlGaN film exhibits an atomic step morphology, with the width of each step ranging from 0.3 μm to 10 μm and the height of each step ranging from -0.1 nm to 50 nm; the surface of the AlGaN also has hexagonal prism three-dimensional island structure points formed by AlGaN growth.
[0054] Feature identification was performed using bright-field and dark-field modes of optical microscopy, see [link / reference]. Figure 3 and Figure 4 , Figure 3 The images provided in this application illustrate the physically unclonable function under a bright field optical microscope, where (a) is an image of an AlGaN thin film under a bright field optical microscope, and (b) is an image of a deposited metal thin film under a bright field optical microscope. Figure 4 The images of physically unclonable functions provided in this application under a dark field optical microscope are shown in (a) and (b) respectively. (a) is an image of an AlGaN thin film under a dark field optical microscope, and (b) is an image of a metal thin film after deposition under a dark field optical microscope. Figure 3 and Figure 4 It is known that AlGaN films without deposited metal films cannot show atomic step morphology under both bright and dark fields of an optical microscope; only the patterned substrate pattern under the film can be seen.
[0055] A 10 nm thick Ti layer and a 50 nm thick Au layer were sequentially formed on the surface of the AlGaN thin film using electron beam evaporation to obtain a physically non-cloning function. The specific process parameters for forming the Ti / Au layer are as follows: 1. Perform AlGaN thin film wafer cleaning pretreatment; 2. Vacuum chamber evaporation and substrate heating; 3. Electron beam evaporation of Ti film 10 nm, deposition rate: 0.1 nm / s; 4. Electron beam evaporation of Au film 50 nm, deposition rate: 0.5 nm / s.
[0056] The physical non-cloning function was tested using AFM, and the results are as follows: Figure 5 As shown, Figure 5 AFM image of a physically unclonable function prepared for an embodiment of this application. (By...) Figure 5 It is known that the physically unclonable functions prepared in this application have atomic step morphology and structural point morphology.
[0057] Feature identification of the physically unclonable function was performed using bright-field and dark-field modes of optical microscopy, see [link to documentation]. Figure 3 and Figure 4 , Figure 3 The images provided in this application illustrate the physically unclonable function under a bright field optical microscope, where (a) is an image of an AlGaN thin film under a bright field optical microscope, and (b) is an image of a deposited metal thin film under a bright field optical microscope. Figure 4 The images of physically unclonable functions provided in this application under a dark field optical microscope are shown in (a) and (b) respectively. (a) is an image of an AlGaN thin film under a dark field optical microscope, and (b) is an image of a metal thin film after deposition under a dark field optical microscope. Figure 3 and Figure 4 As can be seen, the physically unclonable function provided in this application uses a microscope dark-field mode for feature identification, which can clearly identify the atomic step morphology.
[0058] In this embodiment, 100 images of the same PUF were captured, and the intra-Hamming distance of the images was measured, such as... Figure 6 As shown, Figure 6 This application provides a PUF test for intra- and inter-film distances in a dark field using Hamming film. Figure 6 It can be seen that the intra-Hamming distance of the same PUF is less than 0.25. In order to avoid misjudgment, 0.3 is set as the PUF identification criterion. When the Hamming distance is less than 0.3, it is determined to be the same PUF.
[0059] This embodiment captured 100 different PUF recognition images and measured the distance between their Hamming images, such as... Figure 6 As shown, the distance between the Hamming images is greater than 0.45, which can clearly identify whether the PUF images belong to the same PUF or different PUFs.
[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A physically unclonable function, characterized in that, include: Substrate; A semiconductor film is formed on the substrate, the surface of which has an atomic step morphology that can be resolved by an atomic force microscope; A metal film formed on the semiconductor film.
2. The physically unclonable function according to claim 1, characterized in that, The vertical thickness of each atomic step is independently 0.1 nm to 50 nm; The width of each atomic step is independently no greater than 50 μm.
3. The physically unclonable function according to claim 2, characterized in that, The width of each atomic step is independently 0.01 μm to 20 μm.
4. The physically unclonable function according to claim 1, characterized in that, Growth structure points are also formed on the surface of the semiconductor film.
5. The physically unclonable function according to claim 4, characterized in that, The growth structure points are one or more of GaN hexagonal prisms, AlN hexagonal prisms, AlGaN hexagonal prisms, and Si depressions.
6. The physically unclonable function according to any one of claims 1 to 5, characterized in that, The thickness of the semiconductor film is 0.5 μm to 10 μm; The semiconductor film is selected from one or more stacked films of Si film, SiC film, AlN film, GaN film, AlGaN film and BN film.
7. The physically unclonable function according to claim 6, characterized in that, The metal film is selected from one or more of Au film, Al film, Cu film, Ag film, Ti film, Cr film and Ni film; The thickness of the metal film is 10 nm to 500 nm.
8. The physically unclonable function according to claim 6, characterized in that, The substrate is selected from Si wafers, SiC wafers, sapphire, glass wafers or GaN-based substrates; The thickness of the substrate is 100μm to 1000μm.
9. A method for fabricating a physically unclonable function, characterized in that, include: A semiconductor film with an atomic step morphology resolvable by an atomic force microscope is formed on a substrate; A metal film is formed on the semiconductor film.
10. The manufacturing method according to claim 9, characterized in that, Semiconductor films are formed on substrates using metal-organic chemical vapor deposition or molecular beam epitaxy.