CN-122028660-A - System and method for atomic layer etching process and rapid in-situ liner deposition of high aspect ratio structures

Abstract

The invention discloses a system and a method for atomic layer etching technology of a high aspect ratio structure and rapid in-situ liner deposition. The system includes a pressurized precursor buffer disposed proximate to the gas/precursor delivery unit. In-situ liner deposition steps are inserted at predetermined intervals during the ALE process cycle. The system controller monitors the real-time precursor pressure within the buffer to determine and release a controlled volume of precursor to the chamber. Such rapid in-situ liner deposition helps achieve more excellent profile control during HAR etching based on the precise volume of precursor introduced.

Inventors

• PAN YANG

Assignees

• 启迪原子私人有限公司

Dates

Publication Date

20260512

Application Date

20251111

Priority Date

20241112

Claims (20)

1. 1. An ALE process system, comprising: a process chamber for accommodating a substrate and maintaining a vacuum environment required for a plasma-based process; a plasma source coupled to the process chamber for generating a plasma within the process chamber; a gas/precursor distribution unit connected to a gas source for delivering process gases required for the ALE process to the process chamber; a pressurized precursor buffer disposed adjacent to the gas/precursor dispensing unit for storing and releasing a precursor, wherein the pressurized precursor buffer comprises: A buffer structure provided with an inlet and an outlet; a pressure sensor for monitoring the pressure within the precursor; wherein the pressurized precursor buffer is coupled to a valve system to control the flow of precursor from the pressurized precursor buffer to the process chamber; A system controller coupled to the pressurized precursor buffer for: performing an ALE cycle, wherein the ALE cycle comprises a surface modification step and a sputtering step; after a predetermined number of ALE cycles, a rapid in-situ liner deposition step is initiated by releasing precursor from the pressurized precursor buffer.
2. 2. The system of claim 1, wherein the system controller is configured to maintain a position of the movable components of the vacuum valve during the liner deposition step to reduce the time required to establish a stable precursor pressure within the process chamber.
3. 3. The system of claim 1, wherein the precursor is a liquid precursor.
4. 4. The system of claim 3, wherein the liquid precursor is stored in admixture with a carrier gas.
5. 5. A system according to claim 3, wherein the liquid precursor is vaporized upon release from the pressurized precursor buffer and delivered to the process chamber with a carrier gas introduced from the gas source.
6. 6. The system of claim 5, wherein the carrier gas is the same process gas used in the sputtering step.
7. 7. The system of claim 1, wherein the precursor is a gaseous precursor.
8. 8. The system of claim 1, wherein the precursor is released from the pressurized precursor buffer into the process chamber and a plasma within the process chamber is maintained after the sputtering step of a previous ALE cycle is completed, wherein the liner deposition step is performed based on the plasma.
9. 9. The system of claim 8, wherein the sustaining state of the plasma is achieved using different operating parameters than the sputtering step, wherein the operating parameters include different power output by the rf generator and different bias voltages provided by a bias unit, wherein the bias unit is coupled to a chuck for supporting the substrate.
10. 10. The system of claim 1, wherein the pressure sensor in the pressurized precursor buffer is configured to transmit real-time pressure data to a system controller to adaptively adjust precursor release time period according to a process recipe.
11. 11. The system of claim 1, wherein the liner is selected from a metal, a metal oxide, a metal nitride, carbon, carbide, or a metal doped carbon or carbide layer.
12. 12. The system of claim 1, wherein the ALE process is used to form a HAR structure, wherein the HAR structure comprises an ONON stack used to form a 3D NAND device channel hole.
13. 13. The system of claim 1, wherein the ALE process is used to form HAR structures, wherein the HAR structures comprise holes used to form DRAM capacitors.
14. 14. The system of claim 1, wherein the ALE process is used to form a HAR structure, wherein the HAR structure comprises one or more stacks, and wherein the stack material comprises silicon, germanium, a metal, a nitride, an oxide, and carbon.
15. 15. The system of claim 1, wherein the system deposits the liner by an ALD process and performs a punch-through etching step to remove deposited material at the etch front.
16. 16. An ALE method for a HAR structure of a substrate, comprising: Performing ALE cycles within the process chamber, wherein each ALE cycle comprises a surface modifying step and a sputtering step; after a predetermined number of ALE cycles, initiating a rapid in-situ liner deposition step by releasing the precursor from a pressurized precursor buffer disposed adjacent to a gas/precursor distribution unit within the process chamber, and And controlling the precursor release time according to the real-time pressure data of the pressure sensor in the pressurized precursor buffer so as to obtain the controllable liner thickness.
17. 17. The method of claim 16, further comprising dynamically adjusting the precursor release duration based on a process recipe and the real-time pressure data.
18. 18. The method of claim 16, wherein the liner is selected from a metal, metal oxide, metal nitride, carbon, carbide, or metal doped carbon or carbide layer, and the liner is deposited on sidewalls of the HAR structure to form a protective layer.
19. 19. The method of claim 16, wherein the method deposits the liner by an atomic ALD process and performs a punch-through etching step to remove deposited material from the etch front.
20. 20. The method of claim 16, wherein the method employs a PECVD process to deposit the liner and adjusts the step coverage of the liner by varying deposition conditions.

Description

System and method for atomic layer etching process and rapid in-situ liner deposition of high aspect ratio structures Cross Reference to Related Applications The present invention claims priority from U.S. patent application Ser. No. 18/945,487, 11/12 of 2024. Technical Field The invention relates to an Atomic layer etching (Atomic LAYER ETCHING, ALE) process in semiconductor manufacture, which is particularly suitable for High-Aspect-Ratio (HAR) structures in devices such as 3D NAND, DRAM, logic circuits and the like. More particularly, the present invention relates to an ALE system and method that incorporates a rapid in-situ liner deposition technique to enhance etch profile control and reduce sidewall bowing of HAR structures during cyclical etch steps. Background The ongoing progress toward miniaturization of semiconductor devices has resulted in an increasing need for high precision etching processes, particularly in the fabrication of HAR structures such as channel holes in 3D NAND, capacitors in DRAM, and fin field effect transistor (FinFET) like vertical transistor structures in logic devices. HAR structures present significant challenges in plasma etching, primarily because at certain depths it is difficult to achieve uniform removal of material without damaging the desired profile. Conventional ALE processes can precisely control material removal on an atomic scale by alternating surface modification and sputtering steps. However, in HAR applications, these processes often lead to profile deviations and sidewall bending problems, which in turn affect the structural integrity and performance of the final device. To address these issues, an in-situ liner deposition step may be added at selected intervals of the ALE cycle to protect the sidewalls of the HAR structure so as to maintain a desired etch profile throughout the ALE process. However, adding such steps typically adds significant process time and complexity, as conventional systems may require the delivery of precursor materials from external sources, resulting in prolonged step changeover times, and may introduce process delays. Furthermore, existing ALE systems generally lack an efficient mechanism to store and rapidly deliver liner deposition precursors to a process chamber. The time required to introduce these precursors can increase cycle time and impact process throughput. As device structures continue to evolve and shrink, it has become critical to achieve more efficient, integrated precursor delivery and liner deposition methods in ALE processes. The present invention addresses these limitations by introducing a pressurized precursor buffer that is directly disposed within the ALE process system, enabling rapid in-situ liner deposition, and precise control of precursor delivery. The method can not only maintain the integrity of the side wall, but also improve the etching uniformity of the HAR structure, and simultaneously can also improve the reliability and efficiency of an ALE process in advanced semiconductor manufacturing. Disclosure of Invention In some embodiments, the present invention provides an ALE process system that aims to improve profile control and sidewall protection of HAR structures (e.g., channel holes in 3D NAND devices, capacitors in DRAM devices, and fin, gate, and source/drain recess structures prepared for epitaxial layer growth). The system includes a pressurized precursor buffer capable of delivering liner deposition precursor rapidly and directly to a process chamber. In some embodiments, the precursor buffer is integrated with a valve system and a time estimator that coordinates the duration of precursor release based on the measured pressure of the precursor stored in the pressurized buffer and the process recipe. In some embodiments, the ALE process includes a conventional ALE cycle, i.e., a surface modification step (step a) and a sputtering step (step B), followed by an additional liner deposition step (step C). Step C may be introduced after a predetermined number of ALE cycles have elapsed and may be performed at selected intervals of the ALE cycles. The pressurized precursor buffer is capable of storing the precursor under pressure, thereby achieving efficient delivery during step C, eliminating the need for lengthy external precursor supply lines, thereby shortening the step transition time and minimizing process overhead. In certain embodiments, the pressurized precursor buffer comprises a pressure sensor for monitoring the internal pressure. The system controller will use the pressure information to calculate and adjust the precursor release time to ensure the consistency and controllability of the liner thickness and profile. The system controller may contain a time estimator, which is a software program that improves deposition uniformity by using the process recipe and real-time pressure data to determine the optimal release time of the precursor. In some embodiments, a gas/precursor distribut