Gallium-doped hafnium zirconium oxide ferroelectric capacitor and preparation method thereof
Through gallium doping and optimized annealing process, the flip barrier of the HZO ferroelectric film is reduced, the coercive field and durability problems of FeRAM devices are solved, and high-performance capacitive storage functions are realized.
Patent Information
- Application Number
- CN202510173110.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2025-05-13
AI Technical Summary
Existing ultra-large dense hafnium oxide-based ferroelectric random access memory (FeRAM) devices have high coercive fields, operating voltages and early dielectric breakdown problems, affecting their working energy consumption and durability.
By introducing gallium (Ga) element doping, hafnium zirconium oxygen (HZO) ferroelectric films with different gallium doping sites are constructed, and the phase transition process during the annealing process is optimized, the ferroelectric flip barrier is reduced, and the ferroelectric performance of the film is improved.
A ferroelectric capacitor memory with low coercive field and high durability is realized, which improves the ferroelectric flip speed and cyclic durability, and shows excellent ferroelectrode polarization phenomenon under small operating voltage.
Smart Images
Figure CN119997805A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of ferroelectric memory, and in particular to a gallium-doped hafnium zirconium oxide ferroelectric capacitor and a preparation method thereof. Background Art
[0002] Due to its non-volatility, excellent ferroelectricity and CMOS process compatibility, ultra-large and dense hafnium oxide-based ferroelectric random access memory (FeRAM) has been realized, making it an ideal candidate for the next generation of non-volatile memory. However, hafnium oxide belongs to a fluorite structure oxide, and its domain wall effective migration is limited. Ferroelectric switching requires overcoming a large energy barrier, resulting in a higher coercive field, higher operating voltage and early dielectric breakdown, which in turn affects the device's operating energy consumption and durability, limiting its wide application.
[0003] Therefore, in order to improve the performance of FeRAM devices, it is necessary to reduce the coercive field of ferroelectric capacitors to increase the ferroelectric switching speed and device durability. Doping engineering has been proven to be an effective strategy to reduce the coercive field. In recent years, some studies have reduced the coercive field of devices to a certain extent by introducing La, Al, Si and other elements. However, most of the existing studies have sacrificed the residual polarization value of the device, making it difficult for the device to achieve a good balance between ferroelectricity and reliability.
[0004] In view of this, it is necessary to propose a gallium-doped hafnium zirconium oxide ferroelectric capacitor and a preparation method thereof to solve the above problems. Summary of the invention
[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a hafnium oxide-based ferroelectric capacitor and a preparation method thereof, by constructing a hafnium zirconium oxide (HZO) ferroelectric film with different gallium doping sites and optimizing the phase change process during annealing, thereby obtaining a ferroelectric capacitor memory with low coercive field and high durability.
[0006] The purpose of the present invention is achieved through the following technical solutions.
[0007] The present invention provides a gallium-doped hafnium zirconium oxide ferroelectric capacitor, comprising: a substrate, a bottom electrode layer, a gallium-doped hafnium zirconium oxide ferroelectric thin film layer and a top electrode layer which are sequentially arranged on the substrate from bottom to top, wherein the doping concentration of gallium in the gallium-doped hafnium zirconium oxide ferroelectric thin film layer is between 3 and 7 at%.
[0008] In a possible embodiment, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer has a thickness of 5-12 nm.
[0009] In a possible embodiment, the substrate is a high-resistance silicon substrate.
[0010] In a possible embodiment, the material of the bottom electrode layer is tungsten, and the material of the top electrode layer is tungsten; and / or, The thickness of the bottom electrode layer is 20-100 nm, and the thickness of the top electrode layer is 20-100 nm.
[0011] The present invention also provides a method for preparing a gallium-doped hafnium zirconium oxide ferroelectric capacitor, comprising the following steps: S1: Using magnetron sputtering technology, metal is deposited on the substrate as the bottom electrode layer; S2: growing a gallium-doped hafnium zirconium oxide ferroelectric thin film layer on the bottom electrode layer using an atomic layer deposition technique; S3: growing a top electrode layer on the gallium-doped hafnium zirconium oxide ferroelectric thin film layer and patterning the top electrode layer by using photolithography, magnetron sputtering technology, and lift-off process; S4: The wafer is processed using a rapid thermal annealing process to form a final device.
[0012] In a possible embodiment, step S1 includes: A 20-100 nm bottom electrode layer is grown on the substrate by magnetron sputtering technology. During the growth process, the gas flow rate of argon is 50 sccm, the sputtering power is 150 W, the substrate is a high-resistance silicon substrate, and the material of the bottom electrode layer is tungsten.
[0013] In a possible embodiment, step S2 includes: Plasma-Enhanced Atomic Layer Deposition (PEALD) technology is used to grow a gallium-doped hafnium zirconium oxide ferroelectric thin film layer with a thickness of 5~12nm, and the growth process temperature is 250~300℃, wherein a single cycle of PEALD deposition of hafnium oxide growth process includes 0.5s tetrakisdimethylamino hafnium TDMAHf pulse, 6s nitrogen purge, 3s oxygen plasma pulse, and 2s nitrogen purge; a single cycle of PEALD deposition of zirconium oxide growth process includes 0.5s tetrakisdimethylamino zirconium TDMAZr pulse, 6s nitrogen purge, 3s oxygen plasma pulse, and 2s nitrogen purge; a single cycle of PEALD deposition of gallium oxide growth process includes 0.15s trimethylgallium TMGa pulse, 3s nitrogen purge, 2s oxygen plasma pulse, and 2s nitrogen purge, and the gallium doping concentration is 3~7at%.
[0014] In a possible embodiment, step S3 includes: Ultraviolet lithography is used to define the device electrode area, and magnetron sputtering technology is used to grow a top electrode of 20~100nm. During the growth process, the gas flow rate of argon gas is 50sccm, and the sputtering power is 150W. The material of the top electrode layer is tungsten, and a stripping process is used to strip the wafer after the top electrode layer is grown.
[0015] In a possible embodiment, a stripping process is used to strip the wafer after the top electrode layer is grown, including: The wafer after the top electrode layer is grown is placed in acetone for soaking, and is soaked in isopropanol to remove the organic matter remaining on the surface of the wafer, and is washed with deionized water and blown dry with nitrogen.
[0016] In a possible embodiment, step S4 includes: The wafer is subjected to rapid thermal annealing treatment in a nitrogen atmosphere, with a heating rate of 15-20°C / s, an annealing temperature of 400-700°C, and an annealing time of 30-60s.
[0017] The principle of the present invention is as follows: The present invention introduces gallium (Ga) element doping with a smaller ion radius to enhance the stability of the transition state during the reversal process, reduce the reversal barrier of the HZO ferroelectric film, and optimize the phase change process during annealing. Compared with other thin film materials, the gallium-doped hafnium zirconium oxide ferroelectric film layer has a lower ferroelectric reversal barrier, which can accelerate the ferroelectric reversal speed, improve the cycle durability, and realize high-performance capacitor storage function.
[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. Atomic layer deposition technology is used to construct a high dielectric constant gallium-doped hafnium zirconium oxide ferroelectric thin film layer, which is easy to prepare wafer-level memory devices on a large scale.
[0019] 2. The entire preparation process of the gallium-doped hafnium zirconium oxide ferroelectric capacitor of the present invention is completely compatible with complementary metal oxide semiconductor processes.
[0020] 3. The gallium-doped hafnium zirconium oxide ferroelectric capacitor of the present invention has a large residual polarization value while the coercive electric field is reduced, has a fast ferroelectric switching speed and good cycle durability, and has excellent ferroelectric polarization phenomenon at a small operating voltage. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the structure formed after the bottom electrode layer is grown on the substrate according to the present invention.
[0022] Figure 2 It is a schematic diagram of the structure formed after a gallium-doped hafnium zirconium oxide ferroelectric thin film layer is grown on the bottom electrode layer in Example 1.
[0023] Figure 3 It is a schematic diagram of the structure formed after a gallium-doped hafnium zirconium oxide ferroelectric thin film layer is grown on the bottom electrode layer in Example 2.
[0024] Figure 4 It is a schematic diagram of the structure formed after a gallium-doped hafnium zirconium oxide ferroelectric thin film layer is grown on the bottom electrode layer in Example 3.
[0025] Figure 5 It is a schematic diagram of the structure formed after a gallium-doped hafnium zirconium oxide ferroelectric thin film layer is grown on the bottom electrode layer in Example 4.
[0026] Figure 6 It is a schematic diagram of the structure formed after the device electrode region is defined by using ultraviolet photolithography technology in the present invention.
[0027] Figure 7 It is a schematic diagram of the structure formed after the top electrode layer is grown on the surface of the wafer according to the present invention.
[0028] Figure 8 This is a schematic diagram of the device structure formed after the device is subjected to a stripping process according to the present invention.
[0029] Fig. 9 Transmission electron microscope images and electron diffraction patterns of non-Ga-doped HZO ferroelectric thin film samples and Ga-doped HZO ferroelectric thin film samples.
[0030] Fig.10 1 is the hysteresis loop diagram of the Ga-doped HZO ferroelectric thin film sample in Example 1-9.
[0031] Fig.11 1 is the hysteresis loop diagram of the Ga-doped HZO ferroelectric thin film sample in Example 1-3.
[0032] Fig.12 This is a statistical graph showing the variation of the 2 times residual polarization intensity of the Ga-doped HZO ferroelectric thin film sample in Examples 1-3 with the scanning electric field range.
[0033] Fig.13 The cycle endurance of the Ga-doped HZO ferroelectric thin film samples in Examples 1-3 under test pulses at frequencies of 1 MHz and 100 kHz.
[0034] Explanation of the symbols in the drawings: 100, substrate; 200, bottom electrode layer; 300, gallium-doped hafnium zirconium oxide ferroelectric thin film layer; 400, photoresist; 500, top electrode layer. DETAILED DESCRIPTION
[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0036] In view of the problems existing in the prior art, an embodiment of the present invention provides a gallium-doped hafnium zirconium oxide ferroelectric capacitor, see Figure 8 The gallium-doped hafnium zirconium oxide ferroelectric capacitor includes: a substrate 100, a bottom electrode layer 200, a gallium (Ga)-doped hafnium zirconium oxide (HZO) ferroelectric thin film layer 300 and a top electrode layer 500 which are sequentially arranged on the substrate 100 from bottom to top, and the doping concentration of gallium in the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is between 3 and 7 at%.
[0037] In this embodiment, the Ga element with a small ion radius is selected as the doping element to dope the HZO ferroelectric film with a higher remanent polarization value, and the doping concentration of gallium is controlled between 3 and 7 at%. By setting a suitable doping concentration, the coercive field value of the metal-ferroelectric-metal (MFM) capacitor can be significantly reduced while maintaining a suitable remanent polarization value, which is conducive to realizing a ferroelectric capacitor with both ferroelectricity and reliability.
[0038] In one embodiment, see Figure 8 The thickness of the Ga-doped HfZrO ferroelectric thin film layer 300 is 5-12 nm. Within this thickness range, the Ga-doped HZO ferroelectric thin film can exhibit a high remanent polarization value while maintaining a relatively low coercive field, thereby achieving rapid polarization switching and reducing power consumption.
[0039] In one embodiment, see Figure 1 , the substrate 100 is a high-resistance silicon substrate.
[0040] In some embodiments, see Figure 1 and Figure 8 , the material of the bottom electrode layer 200 is tungsten, and the material of the top electrode layer 500 is tungsten; and / or, the thickness of the bottom electrode layer 200 is 20~100nm, and the thickness of the top electrode layer 500 is 20~100nm.
[0041] The present invention also provides a method for preparing a gallium-doped hafnium zirconium oxide ferroelectric capacitor, comprising the following steps: S1: Using magnetron sputtering technology, metal is deposited on the substrate 100 as the bottom electrode layer 200, such as Figure 1 As shown; S2: Using atomic layer deposition technology, grow a gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 on the bottom electrode layer 200, such as Figures 2 to 5 As shown; S3: Using photolithography, magnetron sputtering technology, and lift-off process, a top electrode layer 500 is grown on the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 and the top electrode layer 500 is patterned, such as Figures 6 to 8 As shown; S4: The wafer is processed using a rapid thermal annealing process to form a final device.
[0042] In one embodiment, see Figure 1 Step S1 includes: growing a bottom electrode layer 200 of 20-100 nm on a substrate 100 by magnetron sputtering technology, wherein the gas flow rate of argon gas during the growth process is 50 sccm, the sputtering power is 150 W, the substrate 100 is a high-resistance silicon substrate, and the material of the bottom electrode layer 200 is tungsten.
[0043] In one embodiment, see Figures 2 to 5 Step S2 includes: growing a gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 with a thickness of 5 to 12 nm by plasma-enhanced atomic layer deposition (PEALD) technology, with a growth process temperature of 250 to 300° C., wherein a single cycle of hafnium oxide growth process of PEALD deposition includes a 0.5 s tetrakis(dimethylamino)hafnium TDMAHf pulse, a 6 s nitrogen purge, a 3 s oxygen plasma pulse, and a 2 s nitrogen purge; a single cycle of zirconium oxide growth process of PEALD deposition includes a 0.5 s tetrakis(dimethylamino)zirconium TDMAZr pulse, a 6 s nitrogen purge, a 3 s oxygen plasma pulse, and a 2 s nitrogen purge; a single cycle of gallium oxide growth process of deposition includes a 0.15 s trimethylgallium TMGa pulse, a 3 s nitrogen purge, a 2 s oxygen plasma pulse, and a 2 s nitrogen purge, and the gallium doping concentration is 3 to 7 at%.
[0044] PEALD technology, with its layer-by-layer deposition characteristics, can accurately control the thickness of the film. In the range of 5~12nm, by adjusting the number of deposition cycles, the required thickness of the film can be accurately grown, and the high uniformity and density of the film can be achieved. At a growth temperature of 250~300℃, PEALD technology can grow high-quality HZO films. This temperature range is neither too high to cause a decrease in film quality, nor too low to affect the deposition rate and film performance. By optimizing the time of TDMAHf, TDMAZr and TMGa pulses, nitrogen purge and oxygen plasma pulse parameters, the gallium doping concentration can be accurately controlled in the range of 3~7at%. This precise doping control helps to optimize the electrical properties of the film, such as reducing the coercive field and increasing the residual polarization.
[0045] In one embodiment, see Figures 6 to 8 Step S3 includes: using ultraviolet lithography to define the device electrode area, using magnetron sputtering technology to grow a top electrode of 20~100nm, the gas flow rate of argon gas during the growth process is 50sccm, the sputtering power is 150W, the material of the top electrode layer 500 is tungsten, and the wafer after the top electrode layer 500 is grown is stripped using a stripping process.
[0046] Ultraviolet lithography technology can define the electrode area of the device with high precision. By precisely controlling the exposure and development process of the photoresist 400, a fine pattern at the micron level can be formed to ensure that the size and position of the electrode area meet the design requirements. Magnetron sputtering technology can grow a high-quality tungsten top electrode layer 500 on the wafer. By precisely controlling sputtering parameters such as argon flow rate and sputtering power, a film with excellent electrical properties and mechanical strength can be obtained. At a given sputtering power (150W) and argon flow rate (50sccm), magnetron sputtering technology can achieve a higher sputtering rate and efficiency. The stripping process can transfer the pattern on the photoresist 400 to the tungsten top electrode layer 500 with high precision.
[0047] In one embodiment, a stripping process is used to strip the wafer after the top electrode layer 500 is grown, including: placing the wafer after the top electrode layer 500 is grown in acetone for soaking, soaking it in isopropyl alcohol to remove organic matter remaining on the surface of the wafer, washing it with deionized water and blowing it dry with nitrogen.
[0048] Acetone has good solubility for the photoresist 400. By placing the wafer after the top electrode layer 500 is grown in acetone and soaking it, the photoresist 400 layer on the wafer can be effectively removed, thereby exposing the top electrode area that needs to be retained. Acetone causes less damage to the wafer surface. It will not corrode the metal layer on the wafer or change its properties, thereby ensuring that the wafer after peeling still has good electrical properties and mechanical strength. Isopropyl alcohol can remove residual organic matter on the surface of the wafer, including acetone and other organic contaminants that may remain on the wafer, ensuring the cleanliness of the wafer surface. Using deionized water to clean the wafer can remove the residues of previously used organic solvents (such as acetone and isopropyl alcohol), thereby avoiding the influence of these chemicals on subsequent process steps.
[0049] In one embodiment, step S4 includes: performing rapid thermal annealing on the wafer in a nitrogen atmosphere, with a heating rate of 15-20° C. / s, an annealing temperature of 400-700° C., and an annealing time of 30-60 s.
[0050] The Ga-doped HZO ferroelectric capacitor memory prepared in this embodiment can enhance the stability of the transition state during the flipping process, reduce the flipping barrier of the HZO ferroelectric film, optimize the phase change process during annealing, and is beneficial to the balance between ferroelectricity and durability, thereby realizing high-performance capacitor storage function.
[0051] Example 1 S11: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0052] S12: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S11 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes four large cycles, each of which includes one Small loop and 8 HZO small loops, each The small cycle growth process includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge; each HZO small cycle growth process includes a 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, a 2s nitrogen purge, a 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge. In each large cycle, Deposited on the top, the resulting gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 includes four layers layer and 4 layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and each HZO ferroelectric thin film layer has a corresponding layer Layer, structure like Figure 2 In different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 1 is named t-Ga:HZO; in different Ga doping concentrations, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 1 is named 1 / 16.
[0053] S13: Ultraviolet lithography is used to define the device electrode area on the structure of step S12, and the photoresist 400 is spatially selectively exposed by an ultraviolet light source to achieve pattern transfer, such as Figure 6As shown; a top electrode layer 500 of 20 to 100 nm is grown by magnetron sputtering technology. For example, the material of the top electrode layer 500 is tungsten, the gas flow rate of argon gas during the growth process is 50 sccm, and the sputtering power is 150 W, as shown Figure 7 As shown; the wafer after the top electrode is grown is stripped by a stripping process: first, the wafer is immersed in acetone and allowed to stand until the top electrode layer 500 has a clear structure, then is soaked in isopropanol to remove the organic matter remaining on the surface of the wafer, and finally is washed with deionized water and dried with nitrogen. The structure is shown in FIG. Figure 8 shown.
[0054] S14: Performing a rapid thermal annealing treatment on the wafer obtained in step S13 in a nitrogen atmosphere, with a heating rate of 15°C / s, an annealing temperature of 650°C, and an annealing time of 30s.
[0055] The thin film properties and electrical properties of the sample obtained in Example 1 were characterized by a transmission electron microscope and a semiconductor analyzer. The results showed that Ga doping increased the in-plane tensile stress, resulting in a decrease in the interplanar spacing of the thin film and an increase in the crystallinity. Fig. 9 As shown in the figure, compared with the non-Ga-doped HZO device, the Ga-doped HZO capacitor has a lower coercive field. As the Ga doping ratio decreases, the remanent polarization value increases while the coercive field value increases. When the pulse cycle ratio is 1 / 16, the best compromise is achieved, as shown in the figure. Fig.10 As shown in the figure, the ferroelectric capacitance characteristics of HZO at different Ga doping sites are different. Top doping can achieve a larger residual polarization while reducing the coercive field, such as Fig.11 As shown; higher remnant polarization at small voltage, such as Fig.12 As shown; Durability reaches The device has higher reliability if the cycle is above 100%. Fig.13 shown.
[0056] Example 2 S21: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0057] S22: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S21 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes four large cycles, each of which includes one Small loop and 8 HZO small loops, each The small cycle growth process includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge; each HZO small cycle growth process includes a 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, a 2s nitrogen purge, a 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge. In each large cycle, The gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 thus obtained includes four layers layers and 5 layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and there is a layer of Layer, structure like Figure 3 In different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 1 is named m-Ga:HZO.
[0058] The remaining process steps and process conditions of Example 2 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0059] Example 3 S31: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0060] S32: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S31 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes four large cycles, each of which includes one Small loop and 8 HZO small loops, each The small cycle growth process includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge; each HZO small cycle growth process includes a 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, a 2s nitrogen purge, a 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge. In each large cycle, The gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 thus obtained includes four layers layer and 4 layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer is arranged alternately, and the bottom layer is layer is disposed on the bottom electrode layer 200, each There is a HZO ferroelectric thin film layer on top of the layer, and the structure is as follows Figure 4 In the comparison of different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 1 is named b-Ga:HZO.
[0061] The remaining process steps and process conditions of Example 3 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0062] Example 4 S41: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0063] S42: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S41 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes n large cycles, each of which includes 1 Small loop and 8 HZO small loops, each The small cycle growth process includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge; each HZO small cycle growth process includes a 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, a 2s nitrogen purge, a 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge. In each large cycle, deposited on the top, the resulting gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 includes an n-layer and n layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and each HZO ferroelectric thin film layer has a corresponding layer Layer, n=9, structure as Figure 5 Among the different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 4 is named 1 / 8.
[0064] The remaining process steps and process conditions of Example 4 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0065] Example 5 S51: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0066] S52: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S51 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes n large cycles, each of which includes 1 Small loop and 8 HZO small loops, each The small cycle growth process includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge; each HZO small cycle growth process includes a 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, a 2s nitrogen purge, a 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge. In each large cycle, deposited on the top, the resulting gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 includes an n-layer and n layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and each HZO ferroelectric thin film layer has a corresponding layer Layer, n=7, structure as Figure 5 Among the different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 5 is named 1 / 10.
[0067] The remaining process steps and process conditions of Example 5 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0068] Example 6 S61: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0069] S62: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S61 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes n large cycles, each of which includes 1 Small loop and 8 HZO small loops, each The small cycle growth process includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge; each HZO small cycle growth process includes a 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, a 2s nitrogen purge, a 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge. In each large cycle, deposited on the top, the resulting gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 includes an n-layer and n layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and each HZO ferroelectric thin film layer has a corresponding layer Layer, n=6, structure as Figure 5 Among the different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 6 is named 1 / 12.
[0070] The remaining process steps and process conditions of Example 6 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0071] Example 7 S71: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0072] S72: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S71 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes n large cycles, each of which includes 1 Small loop and 8 HZO small loops, each The small cycle growth process is 0.15s trimethylgallium TMGa pulse, 3s nitrogen purge, 2s oxygen plasma pulse, 2s nitrogen purge; each HZO small cycle growth process includes 0.5s tetrakisdimethylamino hafnium TDMAHf pulse, 6s nitrogen purge, 3s oxygen plasma pulse, 2s nitrogen purge, 0.5s tetrakisdimethylamino zirconium TDMAZr pulse, 6s nitrogen purge, 3s oxygen plasma pulse, 2s nitrogen purge, and each large cycle deposited on the top, the resulting gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 includes an n-layer and n layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and each HZO ferroelectric thin film layer has a corresponding layer Layer, n=5, structure as Figure 5 Among the different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 7 is named 1 / 14.
[0073] The remaining process steps and process conditions of Example 7 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0074] Example 8 S81: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0075] S82: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S81 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes n large cycles, each of which includes 1 Small loop and 8 HZO small loops, each The small cycle growth process is 0.15s trimethylgallium TMGa pulse, 3s nitrogen purge, 2s oxygen plasma pulse, 2s nitrogen purge. Each HZO small cycle growth process includes 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, 6s nitrogen purge, 3s oxygen plasma pulse, 2s nitrogen purge, 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, 6s nitrogen purge, 3s oxygen plasma pulse, 2s nitrogen purge. In each large cycle, deposited on the top, the resulting gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 includes an n-layer and n layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and each HZO ferroelectric thin film layer has a corresponding layer Layer, n=4, structure as Figure 5 Among the different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 8 is named 1 / 18.
[0076] The remaining process steps and process conditions of Example 8 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0077] Example 9 S91: A bottom electrode layer 200 with a thickness of 20-100 nm is grown on the substrate 100 by magnetron sputtering technology. For example, the material of the bottom electrode layer 200 is tungsten. During the growth process, the gas flow rate of argon gas is 50 sccm, the sputtering power is 150 W, and the structure is as follows: Figure 1 shown.
[0078] S92: A 5-12 nm thick gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 is grown on the bottom electrode layer 200 of the structure in step S91 by using an atomic layer deposition technique. The growth process temperature is 250-300° C. The atomic layer deposition process includes n large cycles, each of which includes 1 Small loop and 8 HZO small loops, each The small cycle growth process includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge; each HZO small cycle growth process includes a 0.5s tetrakisdimethylaminohafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, a 2s nitrogen purge, a 0.5s tetrakisdimethylaminozirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge. In each large cycle, deposited on the top, the resulting gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 includes an n-layer and n layers of HZO ferroelectric thin film layers, The HZO ferroelectric thin film layer and the HZO ferroelectric thin film layer are alternately arranged, the HZO ferroelectric thin film layer at the bottom is arranged on the bottom electrode layer 200, and each HZO ferroelectric thin film layer has a corresponding layer Layer, n=4, structure as Figure 5 Among the different gallium (Ga) doping sites, the gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 obtained in Example 8 is named 1 / 20.
[0079] The remaining process steps and process conditions of Example 9 are the same as step S13 and step S14 in Example 1, and are not described again here.
[0080] The technical effects of the gallium-doped hafnium zirconium oxide ferroelectric capacitor and the preparation method thereof of the present invention are explained in detail below.
[0081] 1. The smaller radius of the gallium ion allows it to be more easily embedded in the lattice structure of HZO without causing too much lattice distortion. This doping enhances the stability of the transition state during the ferroelectric reversal process, making the ferroelectric domain more stable when flipping and less susceptible to external interference. Gallium doping also helps to reduce the ferroelectric reversal barrier of HZO ferroelectric films. The reversal barrier is the energy barrier that the ferroelectric domain needs to overcome to flip from one polarization state to another. Lowering the reversal barrier means that the ferroelectric domain is easier to flip, thereby speeding up the ferroelectric reversal.
[0082] 2. Gallium doping can also optimize the phase change process of HZO ferroelectric film during annealing. Annealing is a key step to improve the crystallization quality and performance of the film. By doping with gallium, the phase change process of the film can be regulated, making it easier to form the desired ferroelectric phase, thereby improving the ferroelectric properties of the film.
[0083] 3. Gallium doping reduces the reversal barrier, thereby speeding up the ferroelectric reversal speed. This is crucial for improving the write / read speed of the capacitor. Gallium doping can also improve the cycle durability of the HZO ferroelectric film. Durability refers to the ability of a capacitor to maintain stable performance after experiencing multiple ferroelectric reversals. By doping with gallium, the defects and damage generated in the film during the reversal process can be reduced, thereby improving its durability. The gallium-doped hafnium zirconium oxide ferroelectric film layer 300 has a lower ferroelectric reversal barrier, a faster reversal speed, and a higher cycle durability. These characteristics together realize a high-performance capacitor storage function, allowing the capacitor to store more charge while maintaining stable performance.
[0084] 4. Atomic layer deposition technology is used to construct a gallium-doped hafnium zirconium oxide ferroelectric thin film layer 300 with a high dielectric constant, which makes it easy to achieve large-scale preparation of wafer-level memory devices. Atomic layer deposition technology has the characteristics of high precision, high uniformity and high controllability, and is very suitable for preparing high-quality thin film materials. The entire preparation process of gallium-doped hafnium zirconium oxide ferroelectric capacitors is fully compatible with complementary metal oxide semiconductor (CMOS) processes. This means that the capacitor can be easily integrated into existing CMOS circuits, providing more design flexibility and application prospects in the field of integrated circuits and memory.
[0085] 5. Gallium-doped hafnium zirconium oxide ferroelectric capacitors maintain a large residual polarization value while reducing the coercive electric field. The coercive electric field is the minimum electric field strength required to completely flip the ferroelectric domain. Reducing the coercive electric field means that the capacitor can achieve ferroelectric flipping at a smaller operating voltage, which is crucial for reducing power consumption and improving device performance. The capacitor has excellent ferroelectric polarization at a small operating voltage, and even under a small electric field, the capacitor can show obvious ferroelectric properties, such as an increase in polarization intensity and a change in capacitance value. This is of great significance for realizing high-performance, low-power memory devices.
[0086] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by those with ordinary skills in the field to which the present invention belongs.
Claims
1. A gallium-doped hafnium zirconium oxide ferroelectric capacitor, characterized in that: include: A substrate, a bottom electrode layer, a gallium-doped hafnium zirconium oxide ferroelectric thin film layer and a top electrode layer are sequentially arranged on the substrate from bottom to top, wherein the doping concentration of gallium in the gallium-doped hafnium zirconium oxide ferroelectric thin film layer is between 3 and 7 at%.
2. The gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 1, characterized in that: The thickness of the gallium-doped hafnium zirconium oxide ferroelectric thin film layer is 5-12 nm.
3. The gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 1, characterized in that: The substrate is a high-resistance silicon substrate.
4. The gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 1, characterized in that: The material of the bottom electrode layer is tungsten, and the material of the top electrode layer is tungsten; and / or, The thickness of the bottom electrode layer is 20-100 nm, and the thickness of the top electrode layer is 20-100 nm.
5. A method for preparing a gallium-doped hafnium zirconium oxide ferroelectric capacitor, characterized in that: The following steps are involved: S1: Using magnetron sputtering technology, metal is deposited on the substrate as the bottom electrode layer; S2: growing a gallium-doped hafnium zirconium oxide ferroelectric thin film layer on the bottom electrode layer using an atomic layer deposition technique; S3: growing a top electrode layer on the gallium-doped hafnium zirconium oxide ferroelectric thin film layer and patterning the top electrode layer by using photolithography, magnetron sputtering technology, and lift-off process; S4: The wafer is processed using a rapid thermal annealing process to form a final device.
6. The method for preparing the gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 5, characterized in that: Step S1 includes: A 20-100 nm bottom electrode layer is grown on the substrate by magnetron sputtering technology. During the growth process, the gas flow rate of argon is 50 sccm, the sputtering power is 150 W, the substrate is a high-resistance silicon substrate, and the material of the bottom electrode layer is tungsten.
7. The method for preparing the gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 5, characterized in that: Step S2 comprises: Plasma enhanced atomic layer deposition technology is used to grow a gallium-doped hafnium zirconium oxide ferroelectric thin film layer with a thickness of 5~12nm, and the growth process temperature is 250~300℃, wherein the hafnium oxide growth process of a single deposition cycle includes a 0.5s tetrakis(dimethylamino)hafnium TDMAHf pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge; the zirconium oxide growth process of a single deposition cycle includes a 0.5s tetrakis(dimethylamino)zirconium TDMAZr pulse, a 6s nitrogen purge, a 3s oxygen plasma pulse, and a 2s nitrogen purge; the gallium oxide growth process of a single deposition cycle includes a 0.15s trimethylgallium TMGa pulse, a 3s nitrogen purge, a 2s oxygen plasma pulse, and a 2s nitrogen purge, and the gallium doping concentration is 3~7at%.
8. The method for preparing the gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 5, characterized in that: Step S3 includes: Ultraviolet lithography is used to define the device electrode area, and magnetron sputtering technology is used to grow a top electrode of 20~100nm. During the growth process, the gas flow rate of argon gas is 50sccm, and the sputtering power is 150W. The material of the top electrode layer is tungsten, and a stripping process is used to strip the wafer after the top electrode layer is grown.
9. The method for preparing the gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 5, characterized in that: The wafer after the top electrode layer is grown is subjected to a peeling process, including: The wafer after the top electrode layer is grown is placed in acetone for soaking, and is soaked in isopropanol to remove the organic matter remaining on the surface of the wafer, and is washed with deionized water and blown dry with nitrogen.
10. The method for preparing the gallium-doped hafnium zirconium oxide ferroelectric capacitor according to claim 5, characterized in that: Step S4 comprises: The wafer is subjected to rapid thermal annealing treatment in a nitrogen atmosphere, with a heating rate of 15-20°C / s, an annealing temperature of 400-700°C, and an annealing time of 30-60s.