Plasma enhanced atomic layer deposition system and process with electron gun compensation

Abstract

A kind of plasma enhanced atomic layer deposition system of electron gun compensation, including PEALD reaction cavity: heating substrate table for carrying substrate is equipped inside PEALD reaction cavity, and the sidewall or top of PEALD reaction cavity is opened with electron gun introduction port;Electron gun introduction port place sealed butt joint hot cathode electron gun assembly;Hot cathode electron gun assembly is controlled by precision timing control system;The electrode connection of hot cathode electron gun assembly can adjust the electrical signal output end of negative bias power supply, to apply negative bias to hot cathode, form repulsion acceleration electric field;Plasma source is arranged at the top of PEALD reaction cavity, and plasma source is electrically connected with RF power supply;PEALD reaction cavity is communicated with gas delivery unit;PEALD reaction cavity is communicated with exhaust system, for maintaining the vacuum degree of cavity and discharging waste gas.The present application utilizes the characteristics of active charge neutralization of electron gun and on-demand release, improves the stability of long-period thin film deposition rate and thin film density, realizes the development of high stability, ultra-low defect thin film deposition process.

Description

Technical Field

[0001] This invention belongs to the field of atomic layer deposition technology, specifically relating to an electron gun-compensated plasma-enhanced atomic layer deposition system and process. Background Technology

[0002] Plasma-enhanced atomic layer deposition (PEALD) technology has become a core process in advanced integrated circuit manufacturing due to its excellent low-temperature growth capability, high film density, and excellent step coverage, especially in the fabrication of high-k dielectric layers, insulating barrier layers, and complex three-dimensional nanodevices. PEALD primarily utilizes plasma (such as oxygen, nitrogen, or hydrogen plasma) to provide the activation energy for surface reactions, thus eliminating the dependence on high-temperature environments inherent in traditional thermal ALD. The plasma-enhanced atomic layer deposition system and method disclosed in CN101147247A presents a typical PEALD process method that utilizes highly active plasma to accelerate chemical reduction reactions at the substrate surface to achieve film deposition. However, in such traditional PEALD systems and processes, high-power plasma discharge is often required to improve the reaction rate and film quality, inevitably leading to extremely high concentrations of positive ions and high-energy electrons within the cavity. Because the system lacks an active control and dynamic compensation mechanism for space charge within the reaction chamber and static charge on the substrate surface, it exhibits the following significant technical limitations when performing long-cycle, multi-cycle deposition of insulating or semi-insulating films such as those with high dielectric constants: High-density charge accumulation triggers a severe charging effect, leading to a decrease in deposition rate: In conventional high-power PEALD discharge processes, high-energy electrons in the plasma have long mean free paths and extremely fast diffusion rates, making them highly susceptible to outward diffusion and capture by cavity walls or grounding components. Meanwhile, relatively heavier positive ions are more likely to remain and accumulate on and near the surface of the insulating substrate under the influence of an electric field. In long-cycle, multi-stage continuous deposition processes, this asymmetry in charge capture results in a large accumulation of net positive charge on the surface of the insulating substrate. The positively charged surface generates strong electrostatic repulsion, hindering the arrival of process positive ions in subsequent cycles at the substrate reaction front, causing a significant decrease in the actual deposition rate of the thin film as the process time increases.

[0003] Severe fluctuations in local potential and sheath distortion degrade film uniformity and repeatability: Because traditional PEALD systems cannot provide millisecond-level active dynamic compensation for the evolution of local potential on the substrate surface, the accumulated positive charge on the substrate surface drastically alters the local potential distribution on the wafer surface, leading to severe distortion of the physical properties of the plasma sheath above the wafer. The deflection of the sheath electric field changes the trajectory, energy distribution, and incident flux of process ions, causing drift in reaction kinetics between different regions of the same wafer (e.g., center and edge) and between different process batches, thus compromising the uniformity of film thickness and performance, as well as mass production repeatability.

[0004] Inducing high-intensity localized breakdown electric fields can lead to internal defects and device damage: Furthermore, the continuous accumulation of surface charge from high-power plasma can easily induce high-intensity localized electric fields within the deposited insulating film, causing physical defects such as pinholes, uneven internal stress, and even localized electrical breakdown. This not only reduces the film's density and leakage current blocking performance but also severely degrades the yield and reliability of microelectronic devices, limiting the practical application of existing PEALD technology in the fabrication of critical insulating dielectric layers for very large-scale integrated circuits. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide an electron gun-compensated plasma-enhanced atomic layer deposition system and process, which realizes a dynamic charge compensation unit for atomic layer deposition to eliminate the charge effect; based on the release of accelerated electrons from the thermionic cathode electron gun, the flux and energy of the compensation electrons are precisely controlled and synchronized with the plasma timing; the characteristics of active charge neutralization and on-demand release of the electron gun are utilized to improve the stability and density of long-period thin film deposition rate, and realize the development of a high-stability, ultra-low-defect thin film deposition process.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An electron gun-compensated plasma-enhanced atomic layer deposition system includes a PEALD reaction chamber, a heated substrate stage for supporting a substrate is provided inside the PEALD reaction chamber, and an electron gun inlet port is provided on the side wall or top of the PEALD reaction chamber. The electron gun inlet port is sealed and connected to the hot cathode electron gun assembly for injecting a controllable accelerated electron flow into the substrate reaction region on the heated substrate stage. The hot cathode electron gun assembly is controlled by a precision timing control system; the electrodes of the hot cathode electron gun assembly are connected to the electrical signal output terminal of an adjustable negative bias power supply to apply a negative bias to the hot cathode and form a repulsive accelerating electric field. A plasma source is installed at the top of the PEALD reaction chamber, and the plasma source is electrically connected to the RF power supply; the PEALD reaction chamber is connected to the gas delivery unit; the PEALD reaction chamber is connected to the exhaust system to maintain the vacuum level of the chamber and discharge waste gas.

[0007] The precision timing control system controls the hot cathode electron gun assembly to emit accelerated electron beams as needed during the plasma reaction stage, neutralizing the positive charges accumulated on the substrate surface in real time, maintaining the stability of the local potential of the substrate and the absence of distortion in the plasma sheath, thereby improving the stability of the long-cycle thin film deposition rate and the density of the thin film.

[0008] The gas delivery unit is used to deliver precursors and carrier gas into the PEALD reaction chamber during the precursor adsorption stage, deliver carrier gas or inert gas during the purging stage, and deliver reaction gas during the plasma reaction stage.

[0009] The precision timing control system is a multi-channel programmable logic controller, comprising a signal input terminal, a processor, and a control signal output terminal. The signal input terminal is electrically connected to the signal feedback terminal of the RF power supply and the gas delivery unit, and is used to acquire the plasma pulse and gas path purging operation status signals in real time. The processor is used to extract the plasma pulse and purging timing characteristics of atomic layer deposition based on the operation status signals, and calculate the corresponding trigger time and negative bias pulse width. The control signal output terminal is electrically connected to the pulse enable terminal of the adjustable negative bias power supply, the trigger terminal of the RF power supply, and the valve of the gas delivery unit, respectively, and is used to output control signals based on the calculation results of the processor, so as to coordinate and control the operation pulse timing of the entire system. The precision timing control system, through preset ALD timing characteristics, simultaneously sends a high-level enable signal to the adjustable negative bias power supply when it detects the plasma pulse turned on by the RF power supply, driving the hot cathode electron gun assembly to emit an electron beam; when the plasma pulse ends, it immediately cuts off the negative bias enable signal, causing the electron gun to drop to a micro-current standby state, thereby realizing on-demand dynamic charge compensation.

[0010] The plasma pulse and purge timing characteristics of atomic layer deposition are extracted, and the corresponding trigger time and negative bias pulse width are calculated. The specific implementation method is as follows: Signal Acquisition and Edge Feature Extraction: The signal input terminal of the precision timing control system acquires the output power feedback signal of the RF power supply and the level status signals of the reaction gas valve and carrier gas valve in the gas delivery unit in real time; the PLC processor, through its built-in edge detection algorithm, determines the actual plasma ignition when it detects a rising edge in the output power feedback signal of the RF power supply and the power exceeds the preset ignition threshold, and extracts and records the timestamp T of the current moment. startWhen a falling edge is detected in the power feedback signal, causing it to drop below a preset threshold, or when the carrier gas purge valve is opened, the plasma is determined to be extinguished, and the timestamp T of the current moment is extracted and recorded. end ; Core parameter algorithm calculation: The processor will use the ignition timestamp T start The trigger time set for dynamic charge compensation is directly calculated; simultaneously, the processor calculates the difference ΔT = T between the extinguishing timestamp and the ignition timestamp. end－ T start And set the difference ΔT as the negative bias pulse width; Hardware synchronization control output: When the calculated trigger time is reached, the precision timing control system sends a high-level enable signal to the pulse enable terminal of the adjustable negative bias power supply through the control signal output terminal, driving the hot cathode electron gun assembly to instantly emit an accelerated electron beam; when the high-level duration reaches the calculated negative bias pulse width, the control signal output terminal quickly pulls down the enable signal, so that the hot cathode electron gun assembly returns to the micro-current standby state, achieving millisecond-level precise synchronization with the plasma discharge cycle.

[0011] The gas delivery unit includes a precursor, a reactant gas, a carrier gas, and corresponding gas path control valves and a mass flow controller (MFC).

[0012] The exhaust system includes a vacuum dry pump, a molecular pump, and a pressure regulating valve located on the exhaust pipeline, which are connected in sequence to maintain a preset vacuum level in the cavity and quickly discharge residual gas and reaction byproducts during the purging phase.

[0013] The adjustable negative bias power supply applies a negative bias voltage to the entire hot cathode in the range of -100 V to -1000 V; the hot cathode electron gun assembly uses a high melting point tungsten wire as the hot cathode electron emission source, with the tungsten wire heating current between 2 A and 6 A, and the emitted electron beam current adjustable between 1 mA and 50 mA.

[0014] The hot cathode electron gun assembly includes a high melting point tungsten filament hot cathode, a cathode electrode, and a focusing extraction electrode. The high melting point tungsten filament hot cathode serves as an electron emission source, generating an accelerated electron beam facing the substrate surface under the action of an adjustable negative bias power supply. The high-melting-point tungsten filament thermocathode is electrically connected to the filament heating output terminal of the adjustable negative bias power supply to form a closed-loop heating circuit, which is used to receive the preset heating current provided by the adjustable negative bias power supply and drive the high-melting-point tungsten filament thermocathode to be heated and generate thermionic emission. The cathode electrode is electrically connected to the main negative high voltage output terminal of the adjustable negative bias power supply, and is used to be biased by a negative high voltage of a preset amplitude, so as to establish a main accelerating electric field between the cathode electrode and the substrate, and drive the emitted thermionic electrons to accelerate in a directional manner toward the substrate. The focusing extraction electrode is electrically connected to the focusing control output terminal of the adjustable negative bias power supply, and is used to apply a focusing / extraction bias voltage with a preset potential difference relative to the cathode electrode, so as to form a symmetrically contracting focusing extraction electric field at the front end of the cathode electrode, which is used to constrain the divergence angle of the electron beam and regulate the extraction flux of the thermionic electron beam. The introduction of the accelerated electron beam actively collides and recombines with the positive ions accumulated on the substrate surface and in the surrounding space, neutralizing the local positive charge generated by the charging effect in real time, eliminating electrostatic repulsion, and ensuring that the ions of subsequent process reactions can smoothly reach the film growth front.

[0015] A plasma-enhanced atomic layer deposition process based on electron gun compensation of the above system is characterized by comprising the following steps: Step 1: System Setup and Initialization A plasma-enhanced atomic layer deposition system with an integrated electron gun inlet port was constructed. The hot cathode electron gun assembly, adjustable negative bias power supply, plasma source, heated substrate stage, gas delivery unit and precision timing control system were assembled in sequence. The substrate to be deposited was placed on the heated substrate stage, and the PEALD reaction chamber was vacuum sealed and the environmental parameters were initialized. Step 2: Setting Process Parameters The process parameters are set through a precision timing control system: the adjustable negative bias power supply outputs a negative bias voltage between -100 V and -1000 V, the heating current of the hot cathode tungsten filament is set between 2 A and 6 A, the electron beam current is adjusted between 1 mA and 50 mA, and the divergence coverage diameter is adjusted to completely cover the heated substrate platform; the plasma source power, gas flow rate and process cycle timing are set synchronously. Step 3: Precursor monolayer adsorption (non-compensation stage) The precision timing control system is activated and the standard process cycle is entered. First, the precursor gas is introduced to allow it to complete a single-layer self-limiting adsorption on the substrate surface. At this time, the timing is in the non-plasma reaction stage. The precision timing control system determines that no charge compensation is required, the adjustable negative bias power supply is disconnected, and the hot cathode electron gun assembly maintains a cutoff standby state with extremely low current preheating and does not emit high-energy electron beams. Step 4: First stage inert gas purging (non-compensation stage) After the precursor adsorption is completed, the gas delivery unit introduces carrier gas or inert gas for the first stage of purging, and the exhaust system assists in expelling excess precursor and impurities from the cavity; during the purging process, the hot cathode electron gun assembly remains in a cut-off standby state. Step 5: Plasma Reaction and Dynamic Charge Compensation (On-Demand Compensation Stage) The precision timing control system monitors the output power signal of the RF power supply in real time. Step Six: Second Stage Inert Gas Purging (Non-Compensation Stage) Once the plasma reaction stage ends, the precision timing control system stops triggering the adjustable negative bias power supply, and the hot cathode electron gun assembly returns to a low-level cutoff standby state; simultaneously, carrier gas or inert gas is introduced for the second stage of purging to remove reaction byproducts and excess gas. Step 7: Continuous Deposition in Multiple Cycles Repeat the ALD cycle process from steps three to six above. In each cycle, the electron gun and plasma timing are precisely synchronized through a precision timing control system, and charge compensation is performed as needed. Continue the cycle until the film deposited on the substrate surface reaches the target thickness. After completion, turn off the plasma source and the thermionic electron gun assembly, break the vacuum and take out the sample.

[0016] In step three, the extremely low current is defined as a cathode preheating current of 0.1 A to 1 A.

[0017] Step five specifically involves: When a plasma pulse is detected, dynamic charge compensation is determined to be required. The adjustable negative bias power supply and the hot cathode electron gun assembly are immediately and synchronously triggered. The electron gun instantly emits a directional accelerated electron beam and injects it into the reaction area on the substrate surface to neutralize the positive charge accumulated by the plasma discharge in real time and stabilize the local potential of the plasma sheath and the substrate. When the plasma pulse signal from the RF power supply is detected to end, the precision timing control system stops outputting the trigger signal; the adjustable negative bias power supply is disconnected, and the hot cathode electron gun assembly returns to the extremely low current preheating standby state, completing this round of charge compensation.

[0018] The materials used for the thin films to be deposited in the process include hafnium dioxide (HfO2), zirconium dioxide (ZrO2), alumina (Al2O3), high-k dielectric materials, or insulating silicon nitride (SiN). x (A type of thin film.)

[0019] The beneficial effects of this invention are: This invention utilizes an externally added controllable hot cathode electron gun source to actively emit accelerated electrons into the process cavity or substrate surface, thereby neutralizing the net positive charge accumulated during plasma discharge in real time, and realizing a dynamic charge compensation unit for atomic layer deposition to eliminate the charge effect.

[0020] By precisely controlling the heating current, negative bias voltage, and precise synchronization with the plasma pulse timing of the electron gun, the flux and energy of the compensation electrons can be regulated without changing the existing plasma source structure or performing frequent shutdowns for power removal, thus expanding the application window of the continuous long-cycle PEALD process.

[0021] This invention uses a precision timing control system to control the hot cathode electron gun assembly to emit accelerated electron beams as needed during the plasma reaction stage, thereby neutralizing the positive charges accumulated on the substrate surface in real time. This solves the technical problems of existing PEALD systems when depositing insulating or semi-insulating films over long periods and multiple cycles, such as deposition rate decay due to charge accumulation, plasma sheath distortion, numerous localized breakdown defects in the film, and poor process repeatability.

[0022] Meanwhile, this invention utilizes the accelerated electron beam emitted by the thermionic electron gun assembly to actively neutralize the positive charges accumulated on the substrate surface and in space, eliminating electrostatic repulsion and stabilizing the plasma sheath electric field. Through this microscopic charge compensation principle, the local potential is precisely controlled, ensuring that subsequent reaction ions can smoothly reach the film surface, thereby significantly improving the stability of long-cycle deposition rate and film density, and breaking through the limitation of deposition efficiency by the charge effect. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the electron gun-compensated atomic layer deposition system of the present invention.

[0024] Figure 2 This is a flowchart illustrating the operation of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings.

[0026] like Figure 1 As shown, an electron gun compensated plasma-enhanced atomic layer deposition system includes a PEALD reaction chamber 12: the PEALD reaction chamber 12 is provided with a heated substrate stage 4 for supporting a substrate 3, and a dedicated vacuum flange interface is provided on the side wall or top of the PEALD reaction chamber 12 to form an electron gun inlet port 8. The electron gun inlet port 8 is sealed and connected to the hot cathode electron gun assembly 7, which is used to inject a controllable accelerated electron flow into the substrate reaction region on the heated substrate stage 4. The hot cathode electron gun assembly 7 is controlled by a precision timing control system 2; the electrodes of the hot cathode electron gun assembly 7 are connected to the electrical signal output terminal of the adjustable negative bias power supply 6 to apply a negative bias to the hot cathode and form a repulsive accelerating electric field. The top of the PEALD reaction chamber 12 is provided with a plasma source 10, which is electrically connected to the RF power supply 9; the PEALD reaction chamber 12 is connected to the gas delivery unit; the PEALD reaction chamber 12 is connected to the exhaust system 5 to maintain the vacuum level of the chamber and exhaust waste gas.

[0027] The precision timing control system 2 controls the hot cathode electron gun assembly 7 to emit accelerated electron beams as needed during the plasma reaction stage, neutralizing the positive charges accumulated on the substrate surface in real time, maintaining the stability of the local potential of the substrate and the absence of distortion in the plasma sheath, thereby improving the stability of the long-cycle thin film deposition rate and the density of the thin film.

[0028] The gas delivery unit is used to deliver precursor 13 and carrier gas 1 into PEALD reaction chamber 12 during the precursor adsorption stage, deliver carrier gas 1 or inert gas during the purging stage, and deliver reaction gas 11 during the plasma reaction stage.

[0029] The precision timing control system 2 is a multi-channel programmable logic controller (PLC). The pulse enable terminal of the adjustable negative bias power supply 6, the trigger terminal of the RF power supply 9, and the valve of the gas delivery unit are electrically connected to the control signal output terminal of the precision timing control system 2. The control signal output terminal is used to extract the plasma pulse and purging timing characteristics of atomic layer deposition, calculate the corresponding trigger time and negative bias pulse width, and synchronize them to the process flow to coordinate and control the operating pulse timing of the entire system.

[0030] The precision timing control system 2, through preset ALD timing characteristics, simultaneously sends a high-level enable signal to the adjustable negative bias power supply 6 when it detects that the RF power supply 9 has turned on the plasma pulse, driving the hot cathode electron gun assembly 7 to emit an electron beam; when the plasma pulse ends, it immediately cuts off the negative bias enable signal, causing the electron gun to drop to a micro-current standby state, thereby realizing on-demand dynamic charge compensation.

[0031] The gas delivery unit includes a precursor 13, a reactant gas 11, a carrier gas 1, and corresponding gas path control valves and a mass flow controller (MFC).

[0032] The exhaust system 5 includes a vacuum dry pump, a molecular pump, and a pressure regulating valve located on the exhaust pipeline, which are connected in sequence to maintain a preset vacuum level in the cavity and quickly discharge residual gas and reaction byproducts during the purging stage.

[0033] The adjustable negative bias power supply 6 applies a negative bias voltage to the entire hot cathode within the range of -100 V to -1000 V. The hot cathode electron gun assembly 7 uses a high-melting-point tungsten filament as the hot cathode electron emission source, with a tungsten filament heating current between 2 A and 6 A, and the emitted electron beam current adjustable between 1 mA and 50 mA. The beneficial effect of this parameter setting is that it can provide a sufficient flux of electrons to completely neutralize the net positive charge accumulated on the surface of the insulating film, while avoiding lattice damage or secondary defects caused by excessively high-energy electrons to the fragile film surface.

[0034] The hot cathode electron gun assembly 7 includes a high melting point tungsten filament hot cathode, a cathode electrode, and a focusing extraction electrode. The high melting point tungsten filament hot cathode serves as an electron emission source and generates an accelerated electron beam facing the surface of the substrate 3 under the action of an adjustable negative bias power supply 6. The introduction of the accelerated electron beam actively collides and recombines with the positive ions accumulated on the surface of the substrate 3 and in the surrounding space, neutralizing the local positive charge generated by the charge effect in real time, eliminating electrostatic repulsion, and ensuring that the ions of the subsequent process reaction can smoothly reach the film growth front.

[0035] like Figure 2 As shown, a plasma-enhanced atomic layer deposition process with electron gun compensation includes the following steps; Step 1: Construct a plasma-enhanced atomic layer deposition system with an integrated electron gun inlet port 8. Sequentially assemble the hot cathode electron gun assembly 7, adjustable negative bias power supply 6, plasma source 10, heated substrate stage 4, gas delivery unit, and precision timing control system 2. Place the substrate 3 to be deposited on the heated substrate stage 4, and complete the vacuum sealing and environmental parameter initialization of the PEALD reaction chamber 12.

[0036] Step 2: Set the core process parameters of the electron gun through the precision timing control system 2: the adjustable negative bias power supply 6 outputs a -300 V negative bias voltage, the heating current of the hot cathode tungsten filament is set to 4 A, the electron beam current is adjusted to 10 mA, and the electron beam coverage diameter is set to 200 mm to ensure complete coverage of the heating substrate stage 4 and the substrate 3; simultaneously set the plasma source 10 power to 200 W~500 W, the process gas such as Ar / N2 flow rate to 10~50 sccm, and set the process cycle sequence of plasma treatment and injection to 30~60 cycles.

[0037] Step 3: Start the precision timing control system 2 and enter the standard process cycle. First, introduce the precursor gas 13 to allow it to complete monolayer self-limiting adsorption on the surface of the substrate 3. At this time, the timing is in the non-plasma reaction stage. The control system determines that no charge compensation is required, and the electron gun remains in the off standby state and does not emit high-energy electrons.

[0038] Step 4: After the precursor adsorption is complete, carrier gas 1 or inert gas is introduced for the first stage of purging to remove excess precursor and impurities from the PEALD reaction chamber 12. The electron gun remains on standby during the purging process.

[0039] Step 5: The precision timing control system 2 detects the current plasma pulse cycle of the incoming reactive gas 11, determines that dynamic charge compensation is required, and immediately and synchronously triggers the adjustable negative bias power supply 6 and the hot cathode electron gun assembly 7; the electron gun emits a directional accelerated electron beam, which is injected into the reaction area on the surface of the substrate 3 to neutralize the positive charge accumulated by the plasma discharge in real time, stabilize the local potential of the plasma sheath and the substrate, and ensure that the reactive ions reach the growth surface uniformly.

[0040] Step 6: The plasma reaction stage ends, the control system stops triggering the electron gun negative bias voltage, and the electron gun returns to the micro-current preheating cutoff standby mode; carrier gas 1 is introduced for the second stage of purging, and reaction byproducts and excess gas are removed through the exhaust system 5.

[0041] Step 7: Repeat the ALD cycle process described above, ensuring precise synchronization between the electron gun and plasma timing in each cycle, and performing charge compensation as needed. Continue cycling until the high-k dielectric film, such as HfO2, or the insulating film deposited on the substrate surface reaches the target thickness. After completion, shut down all system components, break the vacuum, and remove the sample to obtain a high-dielectric / insulating film product with good crystallinity, density, and excellent electrical properties.

[0042] The materials used for the thin films to be deposited in the process include hafnium dioxide (HfO2), zirconium dioxide (ZrO2), alumina (Al2O3), high-k dielectric materials, or insulating silicon nitride (SiN). x One type of thin film.

[0043] For thin film materials with different band gaps, dielectric constants, and surface positive ion accumulation characteristics, the negative bias amplitude, cathode heating current, and electron beam current of the adjustable negative bias power supply 6 and the hot cathode electron gun assembly 7 need to be differentiated to ensure that while completely neutralizing the net positive charge, secondary defect damage to the thin film lattice caused by high-energy electrons is avoided. Hafnium dioxide (HfO2) thin film: dielectric constant is approximately 20~25. The adjustable negative bias power supply 6 outputs a main negative bias voltage set from -250 V to -450 V, the thermionic cathode tungsten filament heating current set from 3.2 A to 4.5 A, and the emitted electron beam current adjusted from 8 mA to 20 mA.

[0044] Zirconia (ZrO2) thin film: dielectric constant approximately 25~35. Adjustable negative bias power supply 6 output main negative bias voltage set to -200 V to -400 V, hot cathode tungsten filament heating current set to 3.0 A to 4.0 A, and emission electron beam current adjusted to 5 mA to 15 mA.

[0045] Alumina (Al2O3) thin film: It has a wide bandgap (approximately 8.8 eV) and high insulation properties, but suffers from severe accumulation of positive charge on its surface. The adjustable negative bias power supply 6 outputs a main negative bias voltage set from -450 V to -700 V, the hot cathode tungsten filament heating current set from 4.0 A to 5.5 A, and the emitted electron beam current adjusted from 15 mA to 35 mA.

[0046] Insulating silicon nitride (SiN) x Thin film: The density of interface defect states and internal charge traps is relatively high. The adjustable negative bias power supply 6 outputs a main negative bias voltage set from -350 V to -600 V, the hot cathode tungsten filament heating current is set from 3.5 A to 5.0 A, and the emitted electron beam current is adjusted from 10 mA to 25 mA. Example 1: Hafnium dioxide (HfO2) thin film deposition and compensation Process and electrical parameters: The substrate 3 is placed on the heated substrate stage 4, and the substrate temperature is set to 250 °C. The precursor 13 is tetrakis(dimethylamino)hafnium (TDMAH), and the reaction gas 11 is oxygen (O2) plasma. In the plasma reaction stage of step five, the precision timing control system 2 drives the adjustable negative bias power supply 6 to output a negative bias voltage of -300 V, the heating current of the hot cathode tungsten filament is set to 4.0 A, the output electron beam current is 10 mA, and the negative bias pulse is precisely synchronized with the ignition period of the RF power supply 9 (the pulse width is the same as the plasma discharge time). The deposition cycle number is set to 100 cycles (generating an approximately 10 nm HfO2 thin film).

[0047] Technical Results: Compared to the control group without electron gun charge compensation, the long-period deposition rate decay rate of the obtained 10 nm HfO2 film decreased from 18.5% to 1.2%; the leakage current density under a working electric field of 1 MV / cm decreased from 2.1 × 10⁻⁶. -6 A / cm² decreased to 1.5×10 -8 A / cm²; breakdown electric field strength increased from 4.8 MV / cm to 7.2 MV / cm; interface state density Dit increased from 3.5 × 10⁻⁶. 12 eV -1 cm -2 Significantly reduced to 4.0×10 11 eV -1 cm -2 .

[0048] Example 2: Zirconia (ZrO2) Thin Film Deposition and Compensation Process and electrical parameters: The substrate temperature is set to 220℃. The precursor 13 is tetrakis(ethylmethylamino)zirconium (TEMAZ), and the reaction gas 11 is O2 plasma. During the plasma reaction stage, the adjustable negative bias power supply (6) outputs a negative bias voltage of -250V, the heating current of the hot cathode tungsten filament is set to 3.5 A, and the electron beam current is adjusted to 8 mA, which is synchronized with the plasma discharge timing at the millisecond level.

[0049] Technical effects: Effectively alleviated the local potential fluctuations and sheath distortion caused by high-density positive ions on the surface of substrate 3. The thickness uniformity variance (1-sigma) of the 10nm ZrO2 thin film wafer was optimized from 5.8% in the comparative example to 1.1%; the dielectric constant k value was improved from 19.2 in the comparative example (due to defects and abnormal phase transitions caused by surface positive ion bombardment) and stabilized at 28.5; the hysteresis voltage was reduced from 110 mV to less than 12 mV.

[0050] Example 3: Deposition and Compensation of Alumina (Al2O3) Thin Films Process and electrical parameters: The substrate temperature was set to 300 ℃. The precursor 13 was trimethylaluminum (TMA), and the reactant gas 11 was O2 plasma. During the plasma reaction stage, the adjustable negative bias power supply 6 output a negative bias voltage of -550 V, the heating current of the hot cathode tungsten filament was set to 4.8 A, and the electron beam current was set to 25 mA.

[0051] Technical effects: The electrostatic repulsion effect on the strongly insulating Al2O3 surface is greatly eliminated. During 300 long-cycle deposition, the average single-cycle growth rate remains stable at 0.11 nm / cycle with no obvious signs of decay; the film density is significantly improved, and the wet etching rate in dilute fluoroacetic acid decreases by 42%; the breakdown electric field strength reaches a stable 8.9 MV / cm, and the flat band voltage offset ΔVfb is controlled within 10 mV.

[0052] Example 4: Insulating Silicon Nitride (SiN) x Thin film deposition and compensation Process and electrical parameters: The substrate temperature was set to 350℃. The precursor 13 was trimethylsilaneamine (TSA), and the reaction gas 11 was ammonia / nitrogen (NH3 / N2) mixed plasma. During the plasma reaction stage, the adjustable negative bias power supply 6 output a negative bias voltage of -400 V, the heating current of the hot cathode tungsten filament was set to 4.2 A, and the electron beam current was set to 18 mA.

[0053] Technical effects: It neutralizes the charge accumulation at the silicon nitride growth front, reducing charge traps and micropore pinhole defects inside the film. The resulting 15 nm SiN... x The pinhole defect density of the barrier layer film was reduced to 0.03 cm⁻¹. -2The film refractive index remains within the ideal stoichiometric range of 2.02 to 2.05, exhibiting excellent insulating barrier and dense protective properties.

Claims

1. A plasma-enhanced atomic layer deposition system with electron gun compensation, characterized in that, It includes a PEALD reaction chamber (12), inside which is a heated substrate stage (4) for carrying the substrate (3), and an electron gun inlet port (8) is opened on the side wall or top of the PEALD reaction chamber (12). The electron gun inlet port (8) is sealed and docked with the hot cathode electron gun assembly (7) for injecting a controllable accelerated electron flow into the substrate reaction region on the heated substrate stage (4); The hot cathode electron gun assembly (7) is controlled by a precision timing control system (2); the electrodes of the hot cathode electron gun assembly (7) are connected to the electrical signal output terminal of an adjustable negative bias power supply (6) to apply a negative bias to the hot cathode and form a repulsive accelerating electric field. A plasma source (10) is provided on the top of the PEALD reaction chamber (12), and the plasma source (10) is electrically connected to the RF power supply (9); The PEALD reaction chamber (12) is connected to the gas delivery unit; the PEALD reaction chamber (12) is connected to the exhaust system (5) to maintain the vacuum level of the chamber and discharge waste gas.

2. The plasma-enhanced atomic layer deposition system with electron gun compensation according to claim 1, characterized in that, The precision timing control system (2) controls the hot cathode electron gun assembly (7) to emit accelerated electron beams as needed during the plasma reaction stage, neutralizing the positive charge accumulated on the surface of the substrate (3) in real time, and maintaining the local potential stability of the substrate (3) and the non-distortion of the plasma sheath.

3. The plasma-enhanced atomic layer deposition system with electron gun compensation according to claim 1, characterized in that, The gas delivery unit is used to deliver the precursor (13) and carrier gas (1) into the PEALD reaction chamber (12) during the precursor adsorption stage, deliver the carrier gas (1) or inert gas during the purging stage, and deliver the reaction gas (11) during the plasma reaction stage.

4. The plasma-enhanced atomic layer deposition system with electron gun compensation according to claim 1, characterized in that, The precision timing control system (2) is a multi-channel programmable logic controller, including a signal input terminal, a processor, and a control signal output terminal. The signal input terminal is electrically connected to the signal feedback terminal of the RF power supply (9) and the gas delivery unit, and is used to collect the operating status signals of plasma pulses and gas path purging in real time. The processor is used to extract the plasma pulse and purging timing characteristics of atomic layer deposition based on the operating status signals, and calculate the corresponding trigger time and negative bias pulse width. The control signal output terminal is electrically connected to the pulse enable terminal of the adjustable negative bias power supply (6), the trigger terminal of the RF power supply (9), and the valve of the gas delivery unit, respectively, and is used to output control signals based on the calculation results of the processor, so as to coordinate and control the operating pulse timing of the entire system. The precision timing control system (2) uses preset ALD timing characteristics to simultaneously send a high-level enable signal to the adjustable negative bias power supply (6) when it detects that the RF power supply (9) has turned on the plasma pulse, thereby driving the hot cathode electron gun assembly (7) to emit an electron beam; when the plasma pulse ends, it immediately cuts off the negative bias enable signal, causing the electron gun to drop to a micro-current standby state, thereby realizing on-demand dynamic charge compensation. The plasma pulse and purge timing characteristics of atomic layer deposition are extracted, and the corresponding trigger time and negative bias pulse width are calculated. The specific implementation method is as follows: The signal input terminal of the precision timing control system (2) collects the output power feedback signal of the RF power supply (9) and the level status signals of the reaction gas (11) valve and the carrier gas (1) valve in the gas delivery unit in real time; the PLC processor, through the built-in edge detection algorithm, determines the actual ignition of the plasma when it detects that the output power feedback signal of the RF power supply (9) has a rising edge and the power exceeds the preset ignition threshold, and extracts and records the timestamp T of the current moment. start When the power feedback signal is detected to have a falling edge that falls below the preset threshold or the carrier gas (1) purge valve is opened, the plasma is determined to be extinguished, and the timestamp T of the current moment is extracted and recorded. end ; The processor will activate the timestamp T start The trigger time set for dynamic charge compensation is directly calculated; simultaneously, the processor calculates the difference ΔT = T between the extinguishing timestamp and the ignition timestamp. end－ T start And set the difference ΔT as the negative bias pulse width; When the calculated trigger time is reached, the precision timing control system (2) sends a high-level enable signal to the pulse enable terminal of the adjustable negative bias power supply (6) through the control signal output terminal, driving the hot cathode electron gun assembly (7) to instantly emit an accelerating electron beam; when the high level duration reaches the calculated negative bias pulse width, the control signal output terminal quickly pulls down the enable signal, so that the hot cathode electron gun assembly (7) returns to the micro-current standby state, achieving millisecond-level precise synchronization with the plasma discharge cycle.

5. The electron gun-compensated plasma-enhanced atomic layer deposition system according to claim 1, characterized in that, The gas delivery unit includes a precursor (13), a reactant gas (11), a carrier gas (1), and corresponding gas path control valves and a mass flow controller; The exhaust system (5) includes a vacuum dry pump, a molecular pump and a pressure regulating valve located on the exhaust pipeline connected in sequence, which are used to maintain the preset vacuum level in the cavity and quickly discharge residual gas and reaction by-products during the purging stage.

6. The plasma-enhanced atomic layer deposition system with electron gun compensation according to claim 1, characterized in that, The adjustable negative bias power supply (6) applies a negative bias voltage to the entire hot cathode in the range of -100 V to -1000 V; the hot cathode electron gun assembly (7) uses a high melting point tungsten wire as the hot cathode electron emission source, and its tungsten wire heating current is between 2 A and 6 A, and the emitted electron beam current is adjustable between 1 mA and 50 mA.

7. The plasma-enhanced atomic layer deposition system with electron gun compensation according to claim 1, characterized in that, The hot cathode electron gun assembly (7) includes a high melting point tungsten wire hot cathode, a cathode electrode and a focusing lead-out electrode. The high melting point tungsten wire hot cathode serves as an electron emission source and generates an accelerated electron beam facing the surface of the substrate (3) under the action of an adjustable negative bias power supply (6). The high melting point tungsten filament hot cathode is electrically connected to the filament heating output terminal of the adjustable negative bias power supply (6) to form a closed-loop heating circuit, which is used to receive the preset heating current provided by the adjustable negative bias power supply (6) and drive the high melting point tungsten filament hot cathode to be heated and generate thermionic emission. The cathode electrode is electrically connected to the main negative high voltage output terminal of the adjustable negative bias power supply (6) and is used to be biased by a negative high voltage with a preset amplitude to establish a main accelerating electric field between the cathode electrode and the substrate (3) and drive the emitted thermionic electrons to accelerate in the direction of the substrate (3). The focusing extraction electrode is electrically connected to the focusing control output terminal of the adjustable negative bias power supply (6) and is used to be applied a focusing / extraction bias voltage with a preset potential difference relative to the cathode electrode to form a symmetrically contracting focusing extraction electric field at the front end of the cathode electrode, so as to constrain the divergence angle of the electron beam and regulate the extraction flux of the thermionic electron beam. The introduction of the accelerated electron beam actively collides and recombines with the positive ions accumulated on the surface of the substrate (3) and in the surrounding space, thereby neutralizing the local positive charge generated by the charging effect in real time.

8. A plasma-enhanced atomic layer deposition process based on electron gun compensation of the system according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Construct a plasma-enhanced atomic layer deposition system with an integrated electron gun inlet port (8), and assemble the hot cathode electron gun assembly (7), adjustable negative bias power supply (6), plasma source (10), heated substrate stage (4), gas delivery unit and precision timing control system (2) in sequence; place the substrate to be deposited (3) on the heated substrate stage (4), and complete the vacuum sealing and environmental parameter initialization of the PEALD reaction chamber (12); Step 2: Set process parameters through the precision timing control system (2): the adjustable negative bias power supply (6) outputs a negative bias voltage between -100 V and -1000 V, the heating current of the hot cathode tungsten wire is set between 2 A and 6 A, the electron beam current is adjusted between 1 mA and 50 mA, and the divergence coverage diameter is adjusted to completely cover the heating substrate stage (4); the power, gas flow rate and process cycle timing of the plasma source (10) are set synchronously. Step 3: Start the precision timing control system (2) and enter the standard process cycle. First, introduce the precursor (13) gas to make it complete the monolayer self-limiting adsorption on the surface of the substrate (3). At this time, the timing is in the non-plasma reaction stage. The precision timing control system (2) determines that no charge compensation is needed. The adjustable negative bias power supply (6) is disconnected. The hot cathode electron gun assembly (7) maintains the cutoff standby state of extremely low current preheating and does not emit high-energy electron beams. Step 4: After the precursor adsorption is completed, the gas delivery unit introduces carrier gas (1) or inert gas for the first stage of purging. The exhaust system (5) works together to remove excess precursor and impurities from the cavity. During the purging process, the hot cathode electron gun assembly (7) remains in a standby state. Step 5: The precision timing control system (2) detects the output power signal of the RF power supply (9) in real time; Step 6: The plasma reaction stage ends, the precision timing control system (2) stops triggering the adjustable negative bias power supply (6), and the hot cathode electron gun assembly (7) returns to low level cutoff standby; at the same time, carrier gas (1) or inert gas is introduced to perform the second stage purging to remove reaction byproducts and excess gas; Step 7: Repeat the ALD cycle process from Step 3 to Step 6 above. In each cycle, the electron gun and plasma timing are precisely synchronized through the precision timing control system (2), and charge compensation is performed as needed. Continue cycling until the film deposited on the surface of the substrate (3) reaches the target thickness. After completion, turn off the plasma source (10) and the hot cathode electron gun assembly (7), and remove the sample by breaking the vacuum.

9. The plasma-enhanced atomic layer deposition process with electron gun compensation according to claim 8, characterized in that, In step three, the extremely low current is defined as a cathode preheating current of 0.1 A to 1 A; Step five specifically involves: When a plasma pulse is detected, dynamic charge compensation is required. The adjustable negative bias power supply (6) and the hot cathode electron gun assembly (7) are immediately and synchronously triggered. The electron gun instantly emits a directional accelerated electron beam into the reaction area on the surface of the substrate (3), which neutralizes the positive charge accumulated by the plasma discharge in real time and stabilizes the local potential of the plasma sheath and the substrate. When the plasma pulse signal of the RF power supply (9) ends, the precision timing control system (2) stops outputting the trigger signal; the adjustable negative bias power supply (6) is disconnected, and the hot cathode electron gun assembly (7) returns to the extremely low current preheating standby state, completing this round of charge compensation.

10. The plasma-enhanced atomic layer deposition process with electron gun compensation according to claim 8, characterized in that, The material of the thin film to be deposited in the process is one of hafnium dioxide, zirconium dioxide, high-k dielectric material of alumina, or insulating silicon nitride thin film.

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