A composite dielectric layer integrated with inorganic molecular crystals, and preparation and application thereof
By growing an inorganic molecular crystal layer on the surface of the substrate material and combining atomic layer deposition technology, the problem of uneven dielectric layer quality is solved, and the growth of dielectric material with low leakage current and high dielectric constant is achieved, supporting device miniaturization and low power consumption applications.
Patent Information
- Application Number
- CN202111639579.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-12-29
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2041-12-29
AI Technical Summary
In the prior art, when preparing thin-layer dielectric materials, the quality of the dielectric layer is uneven, resulting in an increase in leakage current, affecting device performance. After the thickness of the traditional SiO2 gate dielectric is reduced to the physical limit, the leakage current caused by the quantum tunneling effect increases, affecting the development of integrated circuits.
The inorganic molecular crystal layer is used as the precursor adsorption site of the dielectric material, and the dielectric material is grown on the surface of the substrate material by atomic layer deposition method. The wettability of the inorganic molecular crystal layer is used to improve the adsorption effect of the dielectric material. Dielectric materials such as HfO2, ZrO2 or Al2O3 are selected, and combined with thermal evaporation and atomic layer deposition technology to form a dense and uniform composite dielectric layer.
It achieves efficient growth of the dielectric layer, reduces leakage current, improves device performance, supports device size reduction and low-power consumption applications, is compatible with semiconductor processes, and is suitable for large-scale production.
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Figure CN114334637B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of semiconductor devices, and more specifically, relates to a composite dielectric layer integrated by using inorganic molecular crystals, and its preparation and application. Background Art
[0002] Today, with the rapid development of microelectronics technology, the feature size of semiconductor devices is continuously reduced according to Moore's law. In order to maintain a sufficiently large gate capacitance to ensure necessary gate control ability, the thickness of the oxide layer of small-size MOS devices has reached a very thin level. When the thickness of the traditional SiO2 gate dielectric is reduced to the physical limit, problems such as an increase in the leakage current of the gate dielectric and a decrease in device safety caused by the quantum tunneling effect have become the bottleneck restricting the continuous development of integrated circuits.
[0003] To solve the problems caused by the traditional SiO2 gate dielectric, it is crucial to develop a dielectric layer with a higher gate capacitance, a lower leakage current, and a thinner thickness. Using atomic layer deposition to prepare dielectric materials is a common method, but whether the precursor substances of the deposition reaction can be chemically adsorbed on the surface of the material to be deposited is the key to realizing atomic layer deposition. However, not all materials can achieve efficient adsorption of atomic layer deposition precursors. Especially when preparing thin-layer dielectric materials, non-uniform nucleation often occurs, resulting in a low-quality dielectric layer and a large leakage current, thus affecting device performance.
[0004] In view of the above problems, in order to achieve efficient integration of the dielectric layer on the material surface, the strategies used need to meet the following requirements: the method is simple, has universality, is easy to scale up, and does not damage the material surface. Developing a dielectric layer preparation method that meets the above requirements is of great significance for improving the performance of transistors, reducing power consumption, large-scale preparation, and size reduction. Summary of the Invention
[0005] The present invention solves the problem in the prior art that non-uniform nucleation often occurs during the preparation of dielectric materials, resulting in a low-quality dielectric layer and a large leakage current, thus affecting device performance. The present invention provides a method for integrating a composite dielectric layer by using inorganic molecular crystals. The inorganic molecular crystal layer has good wettability for the precursors of atomic layer deposition of dielectric materials, which is beneficial to the atomic layer deposition growth of dielectric materials. The preparation method of the present invention is compatible with standard semiconductor processes and can achieve large-scale preparation.
[0006] According to the first aspect of the present invention, there is provided a method for integrating a composite dielectric layer by using inorganic molecular crystals. An inorganic molecular crystal layer is grown on the surface of a substrate material, and then a dielectric material is grown on the surface of the inorganic molecular crystal layer by using atomic layer deposition precursors;
[0007] The inorganic molecular crystal layer is used to enhance the adsorption of the precursor, thereby facilitating the growth of the dielectric material.
[0008] Preferably, the dielectric constant of the dielectric material is greater than or equal to the dielectric constant of silicon dioxide.
[0009] Preferably, the dielectric material is HfO2, ZrO2 or Al2O3, which are obtained by reacting hafnium tetrakis(dimethylamino) with water, zirconium tetrakis(dimethylamino) with water, and trimethylaluminum with water, respectively.
[0010] Preferably, an excessive amount of hafnium tetrakis(dimethylamino), zirconium tetrakis(dimethylamino) or trimethylaluminum vapor is pulsed into the chamber first, so that hafnium tetrakis(dimethylamino), zirconium tetrakis(dimethylamino) or trimethylaluminum is adsorbed on the inorganic molecular crystal layer, and then the unadsorbed vapor is blown away by argon; then an excessive amount of H2O vapor is pulsed into the chamber to react with the compound adsorbed on the inorganic molecular crystal layer, and then the excess H2O vapor is blown away by argon, that is, the dielectric material is grown on the surface of the inorganic molecular crystal layer by atomic layer deposition;
[0011] Preferably, the reaction of H2O vapor with the compound adsorbed on the inorganic molecular crystal layer is recorded as one atomic layer deposition, and the total number of atomic layer depositions of the composite dielectric layer integration method is 10 - 100.
[0012] Preferably, growing the inorganic molecular crystal layer specifically is: using the inorganic molecular crystal material as an evaporation source and depositing it on the surface of the substrate material by thermal evaporation;
[0013] Preferably, the inorganic molecular crystal layer is Sb2O3, S8 or P4Se3.
[0014] Preferably, the substrate material is a hydrophobic material or a hydrophilic material;
[0015] Preferably, the hydrophobic material is molybdenum disulfide or graphene; the hydrophilic material is silicon or silicon dioxide.
[0016] According to another aspect of the present invention, there is provided a composite dielectric layer prepared by any of the above methods.
[0017] Preferably, the thickness of the inorganic molecular crystal layer of the composite dielectric layer is 1 - 4 nanometers; the thickness of the dielectric material of the composite dielectric layer is 1 - 10 nanometers.
[0018] According to another aspect of the present invention, there is provided an application of the composite dielectric layer in a back-gate field effect transistor or a top-gate field effect transistor.
[0019] According to another aspect of the present invention, there is provided an application of the composite dielectric layer in a parallel plate capacitor.
[0020] Generally speaking, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
[0021] (1) The present invention uses an inorganic molecular crystal material as an evaporation source and deposits it on the material surface. The obtained inorganic molecular crystal layer has van der Waals contact with the substrate material and will not damage the surface of the substrate material.
[0022] (2) In the present invention, the inorganic molecular crystal layer has good wettability for the precursors of atomic layer deposition of dielectric materials, which can enable a large amount of adsorption of the precursors of atomic layer deposition of dielectric materials on the surface of the inorganic molecular crystal layer, so that another precursor can react with it efficiently to generate the target substance, which is beneficial to the atomic layer deposition growth of dielectric materials.
[0023] (3) The dielectric constant of the dielectric material selected in the present invention is greater than or equal to that of silicon dioxide, and it has lower leakage current, which can effectively reduce the thickness of the dielectric layer and is beneficial to the application of low-power devices and the reduction of device size.
[0024] (4) Preferably, in the present invention, the equivalent oxide thickness can be reduced to less than 1 nanometer at least after the combination of the Sb2O3 inorganic molecular crystal layer and the dielectric material with high dielectric constant. Description of the Drawings
[0025] Figure 1 is a schematic diagram of growing a dielectric layer on a material using an inorganic molecular crystal in Example 1.
[0026] Figure 2 is an atomic force microscope image of atomic layer deposition of HfO2 on MoS2 with an Sb2O3 molecular crystal layer in Example 1.
[0027] Figure 3 is an atomic force microscope image of atomic layer deposition of HfO2 on MoS2 without an Sb2O3 molecular crystal layer in Example 1.
[0028] Figure 4 is a cross-sectional transmission electron microscope image of depositing an Sb2O3 molecular crystal layer and an HfO2 dielectric material on MoS2 in Example 1.
[0029] Figure 5 is a Raman spectrum of depositing Sb2O3 and atomic layer deposition growth of HfO2 on MoS2 before and after in Example 1.
[0030] Figure 6 is an atomic force microscope image of atomic layer deposition growth of HfO2 on graphene with and without an Sb2O3 molecular crystal layer in Example 2.
[0031] Figure 7It is the atomic force microscope photograph of atomic layer deposition growth of ZrO2 on MoS2 with or without Sb2O3 molecular crystal layer in Example 3.
[0032] Figure 8 It is the transfer characteristic curves of the MoS2 back-gate field effect transistor before and after depositing Sb2O3 and growing HfO2 in Example 4.
[0033] Figure 9 It is the relationship between the capacitance and frequency of the parallel plate capacitor with the Sb2O3 molecular crystal layer and HfO2 dielectric layer prepared in Example 5.
[0034] Figure 10 It is the optical microscope photograph of the MoS2 field effect transistor with the Sb2O3 molecular crystal layer and HfO2 dielectric layer as the top gate dielectric in Example 6.
[0035] Figure 11 It is the transfer characteristic curve of the MoS2 top-gate field effect transistor in Example 6.
[0036] Figure 12 It is the output curve of the MoS2 top-gate field effect transistor in Example 6. Detailed implementation manners
[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0038] The present invention uses an inorganic molecular crystal material as an evaporation source, and deposits it on the material surface by thermal evaporation. A molecular crystal layer with a controllable thickness is deposited on the material surface with the inorganic molecular crystal as the source. The obtained inorganic molecular crystal layer can be used as the nucleation site for the atomic layer deposition process of the dielectric material, and then the dielectric material is grown on the molecular crystal layer by atomic layer deposition.
[0039] The inorganic molecular crystal takes molecular clusters as the basic composition unit. The molecular clusters are connected by weak van der Waals forces and have no unsaturated bonds. Depositing on the material surface can avoid damaging the material surface and maintain the interface state of the material surface.
[0040] Preferably, the evaporation source is selected as Sb2O3 powder, and thermal evaporation is carried out in a coating machine with a high vacuum degree (10 -6 torr), and the deposition thickness can be precisely controlled.
[0041] Preferably, a dielectric material with a high dielectric constant is selected as the dielectric material for atomic layer deposition growth. The thickness is adjustable, enabling large-scale preparation.
[0042] After the combination of the inorganic molecular crystal layer and the dielectric material in the present invention, the equivalent oxide thickness can be reduced to less than 1 nanometer at the lowest, achieving a larger gate capacitance, a smaller device operating voltage, and lower device power consumption.
[0043] Example 1
[0044] Figure 1 It is a schematic diagram of using an inorganic molecular crystal to grow a dielectric layer by atomic layer deposition on the surface of a material in the present invention, including the following steps:
[0045] (1) Heat and sublime the Sb2O3 powder in a coating machine with a high vacuum, deposit it on the SiO2 / Si substrate attached with mechanically exfoliated MoS2 nanosheets, set the deposition thickness to 1 nanometer, and obtain MoS2 covered by a 1-nanometer Sb2O3 thin film after the evaporation is completed.
[0046] (2) Put the substrate covered with a 1-nanometer Sb2O3 molecular crystal layer into the atomic layer deposition chamber for dielectric material growth. Use tetra(dimethylamino)hafnium TDMAHf and H2O as the reaction precursors for HfO2, and use argon as the carrier gas. First, pulse an excessive amount of TMDAHf vapor into the chamber, then use argon to blow away the excess TDMAHf, and then pulse an excessive amount of H2O vapor into the chamber to react with the TDMAHf adsorbed on the inorganic molecular crystal layer. Then use argon to blow away the excess H2O vapor and reaction by-products. The pulse times are 1000 milliseconds and 60 milliseconds respectively, and the purge time is 20 seconds for both. This is one reaction cycle. Set the deposition cycle number to 40, and the thickness is about 4 nanometers. After the growth is completed, obtain MoS2 covered by 4 nanometers of HfO2 and 1 nanometer of Sb2O3.
[0047] Perform Raman spectroscopy characterization on MoS2 before and after the implementation of steps (1) and (2) respectively.
[0048] Perform cross-sectional transmission electron microscopy characterization after the end of step (2).
[0049] Examples 2 - 3
[0050] The operation steps are the same as those in Example 1, except for the different substrate materials and dielectric materials. Among them, graphene prepared by mechanical exfoliation is selected as the substrate material in Example 2, and ZrO2 is selected as the dielectric material for growth in Example 3.
[0051] Example 4
[0052] The operation steps are the same as those in Example 1, except that the obtained MoS2 with Sb2O3 and HfO2 dielectric layers on its surface is fabricated into a back-gate field-effect transistor, and its performance is tested.
[0053] Table 1. Performance comparison of MoS2 back-gate field-effect transistor before and after depositing Sb2O3 and HfO2
[0054]
[0055] Example 5
[0056] The operation steps are the same as those in Example 1, except that a heavily doped single-crystalline Si wafer is selected as the substrate. After mechanically exfoliating graphene onto the Si wafer, 1 nm of Sb2O3 and 4 nm of HfO2 are deposited. Metal electrodes are fabricated on its surface to form a parallel-plate capacitor for testing the capacitance value of the Sb2O3 and HfO2 dielectric layers.
[0057] Example 6
[0058] The operation steps are the same as those in Example 1, except that the obtained MoS2 with Sb2O3 and HfO2 dielectric layers on its surface is fabricated into a top-gate field-effect transistor, and its performance is tested.
[0059] Result analysis
[0060] Figure 1 It is a schematic diagram of growing a dielectric layer on the material surface using inorganic molecular crystals in Examples 1 - 3.
[0061] Figure 2 and Figure 3 It is the atomic force microscope characterization of the HfO2 thin film grown on the MoS2 surface with and without the Sb2O3 molecular crystal layer in Example 1. The results show that the surface of the HfO2 thin film grown on the MoS2 surface is dense, flat, and uniform when there is an Sb2O3 molecular crystal layer, while the surface of the HfO2 thin film grown without the Sb2O3 molecular crystal layer is rough and grows in an island-like manner.
[0062] Figure 4 It is the cross-sectional transmission electron microscope characterization of the MoS2 sample with an Sb2O3 molecular crystal layer and an HfO2 thin film deposited on its surface in Example 1. The results show that the thickness of the Sb2O3 and HfO2 thin films deposited on the MoS2 surface is below 5 nm and is dense and uniform.
[0063] Figure 5 It is the Raman spectroscopy characterization of the MoS2 surface before and after depositing Sb2O3 and HfO2 in Example 1. The results show that the Raman vibration modes of MoS2 do not change and the peak positions do not shift, indicating that the deposition of the Sb2O3 molecular crystal layer and the growth of the HfO2 dielectric material do not damage the MoS2 surface.
[0064] Figure 6 It is the atomic force microscope characterization of the HfO2 thin film grown on the graphene surface with and without the Sb2O3 molecular crystal layer in Example 2. The results show that the surface of the HfO2 thin film grown on the graphene surface is dense, flat and uniform when there is an Sb2O3 molecular crystal layer, while the surface of the HfO2 thin film grown without the Sb2O3 molecular crystal layer is rough and grows in an island-like manner.
[0065] Figure 7 It is the atomic force microscope characterization of the ZrO2 thin film grown on the MoS2 surface with and without the Sb2O3 molecular crystal layer in Example 3. The results show that the surface of the ZrO2 thin film grown on the MoS2 surface is dense, flat and uniform when there is an Sb2O3 molecular crystal layer, while the surface of the ZrO2 thin film grown without the Sb2O3 molecular crystal layer is rough and grows in an island-like manner.
[0066] Figure 8 It is the transfer characteristic curve of the back-gated MoS2 field-effect transistor in Example 4. The results show that after depositing the Sb2O3 molecular crystal layer and the HfO2 dielectric layer on the MoS2 surface, the transistor performance is improved, the transconductance and carrier mobility increase, and the threshold voltage decreases.
[0067] Figure 9 It is the capacitance-frequency curve of the parallel-plate capacitor prepared in Example 5. The results show that the capacitance value of the dielectric layer composed of 1 nm Sb2O3 and 4 nm HfO2 is about 3.45 μF / cm 2 or so, and the equivalent oxide thickness is converted to 1 nm.
[0068] Figure 10 It is the optical microscope photo of the MoS2 top-gated field-effect transistor prepared in Example 6. Bi / Au is used as the electrodes for both the top gate and the source-drain electrodes.
[0069] Figure 11 It is Figure 10 the transfer characteristic curve of the field-effect transistor in. The results show that the field-effect transistor has a subthreshold swing of 60 and an on / off ratio of 10 8 and the operating voltage is less than 0.8 V, and the gate leakage current is also in the fA order of magnitude, proving low power consumption.
[0070] Figure 12 It is Figure 10 the output curve of the field-effect transistor in. The linear output characteristic curves at different gate voltages show that the source-drain electrodes are ohmic contacts.
[0071] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for integrating a composite dielectric layer using inorganic molecular crystals, characterized in that, Using Sb2O3 powder as an evaporation source, it is deposited on the surface of the substrate material by thermal evaporation to obtain an Sb2O3 crystal layer; then a dielectric material is grown on the surface of the Sb2O3 crystal layer using an atomic layer deposition precursor. The Sb2O3 crystal layer is used to enhance the adsorption of the precursor, thus facilitating the growth of the dielectric material.
2. The method for integrating a composite dielectric layer using an inorganic molecular crystal as claimed in claim 1, wherein The dielectric constant of the dielectric material is greater than or equal to the dielectric constant of silicon dioxide.
3. The method for integrating a composite dielectric layer using an inorganic molecular crystal according to claim 2, wherein The dielectric material is HfO2, ZrO2 or Al2O3, which are obtained by reacting hafnium tetrakis(dimethylamino) with water, zirconium tetrakis(dimethylamino) with water, and trimethylaluminum with water, respectively.
4. The method for integrating a composite dielectric layer using an inorganic molecular crystal according to claim 3, wherein First, an excessive amount of hafnium tetrakis(dimethylamino), zirconium tetrakis(dimethylamino) or trimethylaluminum vapor is pulsed into the chamber to adsorb hafnium tetrakis(dimethylamino), zirconium tetrakis(dimethylamino) or trimethylaluminum on the Sb2O3 crystal layer, and then the unadsorbed vapor is blown away using argon; then an excessive amount of H2O vapor is pulsed into the chamber to react with the compound adsorbed on the Sb2O3 crystal layer, and then the excess H2O vapor is blown away using argon, that is, a dielectric material is grown on the surface of the Sb2O3 crystal layer by atomic layer deposition.
5. The method for integrating a composite dielectric layer using an inorganic molecular crystal according to claim 4, wherein Denote the reaction of H2O vapor with the compound adsorbed on the Sb2O3 crystal layer as one atomic layer deposition, and the total number of atomic layer depositions of the composite dielectric layer integration method is 10 - 100.
6. The method for integrating a composite dielectric layer using an inorganic molecular crystal as claimed in claim 1, wherein The substrate material is a hydrophobic material or a hydrophilic material.
7. The method for integrating a composite dielectric layer using an inorganic molecular crystal according to claim 6, wherein The hydrophobic material is molybdenum disulfide or graphene; the hydrophilic material is silicon or silicon dioxide.
8. The composite dielectric layer prepared by the method according to any one of claims 1 - 7.
9. The composite dielectric layer according to claim 8, wherein, The thickness of the Sb2O3 crystal layer of the composite dielectric layer is 1 - 4 nanometers; the thickness of the dielectric material of the composite dielectric layer is 1 - 10 nanometers.
10. The application of the composite dielectric layer according to claim 8 or 9 in a back-gate field-effect transistor or a top-gate field-effect transistor.
11. The application of the composite dielectric layer according to claim 8 or 9 in a parallel plate capacitor.