Preparation method of high-quality ultrathin GeTe film based on self-seed layer induction
By introducing the seed layer in the early stage of the growth of GeTe film and growing the subsequent films at intervals, the problem of poor crystallinity of GeTe films is solved, and the preparation of high-quality ultra-thin GeTe films is achieved.
Patent Information
- Application Number
- CN202510337996.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-17
AI Technical Summary
The prior art is difficult to effectively alleviate the impact of the orderly Peierls distortion on subsequent film growth in the early stage of GeTe film growth, resulting in poor film crystallinity.
Using a pulsed laser deposition and growth method based on self-seed layer induced pulsed laser deposition and growth method, an ultra-thin GeTe self-seed layer with a thickness of 0.5-2nm was grown on the surface of the oxide crystal substrate, and subsequent GeTe films were then grown at intervals on their surfaces. By adjusting the growth temperature and insulation time, each film was ensured to fully crystallize.
By introducing the seed layer, the crystal quality of the GeTe film is significantly improved, the crystallinity of the film is improved, and the layered growth is approaching, solving the problem of poor crystallinity of the film.
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Figure CN120158716A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and particularly relates to a method for preparing a high-quality ultrathin GeTe film based on self-seed layer induction. Background Art
[0002] With the development of electronic information technology, data-intensive industries such as the Internet of Things and artificial intelligence are booming day by day, and there is an urgent need for new non-volatile (NVM) memories with fast speed, high density, and low power consumption. In particular, phase change memory has the potential to be used as both main memory and external memory due to its non-volatile and byte-addressable characteristics. Therefore, it is considered one of the new NVM technologies with great development prospects and the most likely to completely replace DRAM. Chalcogenides, such as GeTe, are important phase change materials. However, since the PCM technology relies on the thermal effect of current to realize the mutual transformation of the phase change material between the crystalline state and the amorphous state, in order to reduce the operating power consumption of a single phase change memory cell, it is necessary to further reduce the volume of each phase change unit. Currently, methods such as surface passivation and substrate reconstruction are mainly used to relieve the stress accumulation caused by lattice mismatch, but the above methods require high-temperature pretreatment of the substrate and the atoms in the passivation layer have a certain degree of interference with the subsequent device performance measurement. Therefore, the preparation method of high-quality ultrathin films is extremely critical. Summary of the Invention
[0003] Therefore, in order to overcome the deficiencies of the existing technical means, the present invention provides a method for preparing a high-quality ultrathin GeTe film based on self-seed layer induction, which can effectively relieve the influence on the growth of the subsequent film caused by the suppression of the ordered Peierls distortion in the initial stage of the GeTe film growth.
[0004] To achieve the above object, the present invention adopts the following technical solutions:
[0005] Provide a method for preparing a high-quality ultrathin GeTe film based on self-seed layer induction, comprising the following steps:
[0006] (1) Using the pulsed laser deposition growth method, grow an ultrathin GeTe self-seed layer with a thickness of 0.5 - 2 nm on the surface of an oxide crystal substrate, the growth temperature is 150 - 250 °C, and the heat preservation time of the ultrathin GeTe self-seed layer is 5 min - 1 h;
[0007] (2) After the growth of the ultra-thin GeTe self-seed layer is completed, continue to use the pulsed laser deposition growth method to grow subsequent GeTe thin films at intervals on the surface of the ultra-thin GeTe self-seed layer, and finally obtain a high-quality ultra-thin GeTe thin film. The growth temperature of the subsequent GeTe thin film is 150 - 250 °C, and after each growth of 1 - 2 nm of the subsequent GeTe thin film, it is kept warm for 5 - 30 min to ensure that each layer of GeTe thin film is fully crystallized.
[0008] Further, in step (1), the oxide crystal substrate is alumina (Al2O3).
[0009] Further, in step (1), the growth pressure of the ultra-thin GeTe self-seed layer is 10 -4 Pa, in a high-vacuum environment.
[0010] Further, in step (1), the thickness of the ultra-thin GeTe self-seed layer is 1 nm.
[0011] Further, in step (1), the growth temperature is 220 °C and the heat preservation time is 30 min, which greatly reduces the deposition temperature and reduces the defects caused by the thermal effect during the film preparation process.
[0012] Further, in step (2), the growth temperature of the subsequent GeTe thin film is 220 °C, which is the same as the growth temperature of the self-seed layer, to avoid the recrystallization behavior of the self-seed layer.
[0013] Further, the thickness of each layer of the subsequent GeTe thin film is 1 nm, and the heat preservation time for each layer of the subsequent GeTe thin film is 10 min.
[0014] Further, after the growth of the high-quality ultra-thin GeTe thin film is completed and cooled to room temperature, finally, a layer of alumina thin film is covered on the surface as a protective layer.
[0015] Further, the thickness of the alumina thin film is 10 nm.
[0016] Further, the thickness of the high-quality GeTe thin film is 4 nm.
[0017] The beneficial effects of the method for preparing a high-quality ultra-thin GeTe thin film based on self-seed layer induction provided by the present invention are as follows:
[0018] By using the pulsed laser deposition technology, the crystallinity of the interface self-seed layer is improved, and the growth of the subsequent GeTe thin film is induced, thereby improving the crystal quality of the ultra-thin GeTe thin film.
[0019] Using the method of "self-seed layer" intermittent growth, the crystallinity of the ultrathin GeTe film is improved without a hetero-passivation layer on the substrate surface, providing ideas for the high-quality growth of more transition metal sulfide films. Description of the Drawings
[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0021] Figure 1 It is a characterization diagram of the film spherical aberration microstructure grown by the self-seed layer intermittent growth adopted by the present invention;
[0022] Figure 2 It is a characterization diagram of the film spherical aberration microstructure directly grown without a seed layer. Detailed Embodiments
[0023] The technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0024] Embodiment 1:
[0025] A method for preparing a high-quality ultrathin GeTe film based on self-seed layer induction is provided, including the following steps:
[0026] (1) On the surface of an alumina substrate, using the PLD growth method, the growth temperature is 220 °C, a GeTe self-seed layer with a thickness of 1 nm is grown and kept warm for 30 min.
[0027] (2) After the growth of the self-seed layer is completed, three layers of GeTe films are intermittently grown on its surface using the PLD growth method. The growth temperature is 220 °C, and the thickness of each layer of GeTe film is 1 nm, and each layer is kept warm for 10 min.
[0028] (3) After the growth of the GeTe film is completed, a 10-nm-thick alumina film is deposited on its surface at room temperature as a protective layer to prevent the surface oxidation of the ultrathin GeTe film.
[0029] As Figure 1 shown, the prepared high-quality ultrathin GeTe film has crystallinity, and the crystallinity of the film is the best.
[0030] Example 2
[0031] Change the thickness of the GeTe self-seed layer in step (1) of Example 1 to 0.5 nm, and change the thickness of the GeTe thin film in step (2) to 1.16 nm. With all other conditions remaining the same, the prepared high-quality ultra-thin GeTe thin film has crystallinity.
[0032] Example 3
[0033] Change the thickness of the GeTe self-seed layer in step (1) of Example 1 to 2 nm, and change the GeTe thin film in step (2) to a single layer with a thickness of 2 nm. With all other conditions remaining the same, the prepared high-quality ultra-thin GeTe thin film has crystallinity.
[0034] Example 4
[0035] Change the heat preservation time of each layer of thin film in step (2) of Example 1 to 5 min. With all other conditions remaining the same, the prepared high-quality ultra-thin GeTe thin film has crystallinity.
[0036] Example 5
[0037] Change the heat preservation time of each layer of thin film in step (2) of Example 1 to 20 min. With all other conditions remaining the same, the prepared high-quality ultra-thin GeTe thin film has crystallinity.
[0038] Example 6
[0039] Change the heat preservation time of each layer of thin film in step (2) of Example 1 to 30 min. With all other conditions remaining the same, the prepared high-quality ultra-thin GeTe thin film has crystallinity.
[0040] Example 7
[0041] Change each layer of thin film in step (2) of Example 1 to grow directly without heat preservation. With all other conditions remaining the same, the prepared GeTe thin film is in an amorphous state as a whole.
[0042] Example 8
[0043] Change the growth temperature of both step (1) and step (2) in Example 1 to 150 °C. With all other conditions remaining the same, the prepared high-quality ultra-thin GeTe thin film has crystallinity. The growth temperature of the GeTe thin film in step (2) is the same as that of the self-seed layer, avoiding the recrystallization behavior of the self-seed layer.
[0044] Example 9
[0045] The growth temperatures in steps (1) and (2) of Example 1 were both changed to 250 °C, and the other conditions were the same. The prepared high-quality ultrathin GeTe film had crystallinity. The growth temperature of the subsequent GeTe film was consistent with the growth temperature of the self-seed layer. The growth temperature of the GeTe film in step (2) was consistent with the growth temperature of the self-seed layer, avoiding the recrystallization behavior of the self-seed layer.
[0046] Comparative Example 1
[0047] The difference between Comparative Example 1 and Example 1 was that there was no continuous growth of the seed layer, and the film thickness was strictly controlled at 4 nm, and the other conditions were the same.
[0048] The film of Example 1 was sliced by FIB and characterized by spherical aberration electron microscopy for its microstructure, as Figure 1 and Figure 2 shown, Figure 1 (a) and Figure 1 (a) were the film microstructures of Example 1 and Comparative Example 1 respectively, Figure 1 (b) and Figure 2 (b) were the enlarged views of the local structures of the films of Example 1 and Comparative Example 1 respectively, Figure 1 (c) and Figure 2 (c) were the fast Fourier transform crystallization diagrams of Example 1 and Comparative Example 1 respectively, as Figure 1 shown. It could be seen that in the case of having a self-seed layer, the overall crystallization quality of the film was good and showed a tendency of layered growth. And as Figure 2 shown, in the case of having no self-seed layer, the XRD characterization results showed that the film was in an amorphous state as a whole. Thus, it can be seen that the presence or absence of a self-seed layer has a great influence on the crystallization quality of film growth.
[0049] In summary, the present invention introduces a self-seed layer, enables the initial self-seed layer to be fully crystallized, reduces the surface roughness, makes the subsequent film approach layered growth, and is beneficial to the crystallization of subsequent film growth.
[0050] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0051] The above is the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims
1. A method for preparing high-quality ultra-thin GeTe films based on self-seed layer induction, characterized in that: The following steps are involved: (1) growing an ultra-thin GeTe self-seed layer with a thickness of 0.5-2 nm on the surface of an oxide crystal substrate by a pulsed laser deposition growth method, the growth temperature is 150-250° C., and the holding time of the ultra-thin GeTe self-seed layer is 5 min-1 h; (2) After the growth of the ultra-thin GeTe self-seed layer is completed, a pulsed laser deposition growth method is continued to be used on the surface of the ultra-thin GeTe self-seed layer to intermittently grow subsequent GeTe films, and finally a high-quality ultra-thin GeTe film is obtained. The growth temperature of the subsequent GeTe film is 150-250° C., and the subsequent GeTe film is kept warm for 5-30 minutes after each growth of 1-2 nm.
2. The method for preparing high-quality ultra-thin GeTe films based on self-seed layer induction according to claim 1, characterized in that: In the step (1), the oxide crystal substrate is aluminum oxide.
3. The method for preparing high-quality ultra-thin GeTe film based on self-seed layer induction according to claim 1, characterized in that: In the step (1), the ultra-thin GeTe self-seed layer growth pressure is 10 -4 Pa, in a high vacuum environment.
4. The method for preparing high-quality ultra-thin GeTe films based on self-seed layer induction according to claim 1, characterized in that: In the step (1), the thickness of the ultra-thin GeTe self-seed layer is 1 nm.
5. The method for preparing high-quality ultra-thin GeTe film based on self-seed layer induction according to claim 1, characterized in that: In the step (1), the growth temperature is 220° C. and the insulation time is 30 minutes.
6. The method for preparing high-quality ultra-thin GeTe film based on self-seed layer induction according to claim 1, characterized in that: In the step (2), the subsequent growth temperature of the GeTe film is 220°C.
7. The method for preparing high-quality ultra-thin GeTe film based on self-seed layer induction according to claim 1, characterized in that: In the step (2), the thickness of each subsequent GeTe film layer is 1 nm, and the insulation time of each subsequent GeTe film layer is 10 min.
8. The method for preparing high-quality ultra-thin GeTe film based on self-seed layer induction according to claim 1, characterized in that: After the high-quality ultra-thin GeTe film is grown and cooled to room temperature, a layer of aluminum oxide film is finally covered on the surface as a protective layer.
9. The method for preparing high-quality ultra-thin GeTe film based on self-seed layer induction according to claim 8, characterized in that: The aluminum oxide film has a thickness of 10 nm.
10. The method for preparing high-quality ultra-thin GeTe film based on self-seed layer induction according to claim 1, characterized in that: The high-quality ultra-thin GeTe film has a thickness of 4 nm.