Method and apparatus for controlling the thickness of a protective film on a substrate

Abstract

A method of forming a film on a substrate including an etch layer and a mask formed on the etch layer is provided. The method includes: (a) exposing the substrate to a precursor in a reaction chamber to dispose precursor particles on at least sidewalls of a recess in the etch layer; (b) supplying an inhibitor gas and a modification gas to the reaction chamber to generate a plasma; and (c) modifying the precursor particles on the sidewalls to a protective film while the inhibitor gas and the modification gas are supplied in the reaction chamber.

Description

Technical Field

[0001] This disclosure relates to the etching of a substrate. More specifically, this disclosure relates to a method and apparatus, as part of an etching process, utilizing a protective film to protect the sidewalls of a groove to form a groove with a high aspect ratio. Background Technology

[0002] With the introduction of new technologies, semiconductor manufacturing methods have been improved, thus reducing the size of integrated circuits (ICs, microelectronic circuits, microchips, or simply "chips") manufactured as individual units, as well as the feature size of components on ICs. Miniaturized active and passive semiconductor devices and interconnects are fabricated on semiconductor substrates (e.g., silicon). To form an IC, the substrate undergoes several processes (e.g., doping, ion implantation, etching, thin film deposition of various materials, and photolithographic patterning). Finally, the individual microcircuits are separated by dicing and then individually packaged as ICs.

[0003] The specific process steps used to form ICs on a substrate include atomic layer deposition (ALD), chemical vapor deposition (CVD), and atomic layer etching (ALE). In some conventional processes, etching conditions are varied depending on the depth of the pattern formed. For example, in some conventional processes, chamber pressure, RF power, and process gas flow rate ratio are varied according to the depth of the pattern formed.

[0004] The degradation (e.g., warping) of the sidewall shape caused by lateral etching (or transverse etching) is a problem in conventional etching processes. Typically, a protective film is formed on the sidewalls of the etched groove using ALD, CVD, or other processes. When the protective film is formed to have a sufficiently large uniform thickness to suppress transverse etching, the aperture size of the mask pattern decreases, leading to aperture blockage. Alternatively, when a sub-conformal ALD process (with a film thickness thicker at the top than at the bottom) is used to form a protective film in areas of the groove susceptible to transverse etching, the aperture size of the mask pattern decreases, resulting in aperture blockage. Summary of the Invention

[0005] According to an embodiment, a method for forming a film on a substrate including an etched layer and a mask formed on the etched layer is provided. The method includes: (a) exposing the substrate to a precursor in a reaction chamber to dispose precursor particles on at least the sidewalls of a groove in the etched layer; (b) supplying an inhibitor gas and a modifying gas to the reaction chamber to generate plasma; and (c) modifying the precursor particles on the sidewalls into a protective film while the inhibitor gas and the modifying gas are supplied in the reaction chamber.

[0006] The preceding paragraphs are provided in a general manner and are not intended to limit the scope of the following claims. The described embodiments and further advantages will be well understood with reference to the following description taken in conjunction with the accompanying drawings. Attached Figure Description

[0007] When considered in conjunction with the accompanying drawings, the present disclosure and its many benefits will become more readily understood and thus allow for a more comprehensive evaluation by referring to the following detailed description.

[0008] Figure 1 The etched grooves with curved sidewalls are shown.

[0009] Figure 2 An exemplary substrate processing system according to this disclosure is shown.

[0010] Figure 3 An etching apparatus of an exemplary substrate processing system is shown.

[0011] Figure 4 An exemplary processing circuit that performs computer-based operations according to the present disclosure is shown.

[0012] Figure 5 This is a flowchart of an exemplary etching method.

[0013] Figures 6A to 6C Etched grooves are shown when using a protective film with a subconformal ALD according to an embodiment of this disclosure.

[0014] Figures 7A to 7C This is an exemplary timing diagram for forming a protective film.

[0015] Figure 8 The embodiments of this disclosure are shown to affect the thickness of the protective film at the mask opening.

[0016] Figures 9A to 9C Another embodiment of this disclosure is shown, wherein a protective film is also formed on the bottom surface of the grooves in the etched layer. Detailed Implementation

[0017] The following description, taken in conjunction with the accompanying drawings, is intended to illustrate various embodiments of the disclosed subject matter and is not necessarily intended to represent the only embodiment. In some cases, the description includes specific details to provide an understanding of the disclosed subject matter. However, it will be apparent to those skilled in the art that embodiments can be practiced without these specific details. In some cases, known structures and components are shown in block diagram form to avoid obscuring the concept of the disclosed subject matter.

[0018] Throughout this specification, the terms "an embodiment" or "embodiment" refer to a particular feature, structure, or characteristic described in connection with an embodiment, which is included in at least one embodiment of the disclosed subject matter. The phrases "in one embodiment" or "in an embodiment" appearing in different places in the specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, characteristics, operations, or functions may be combined in any suitable manner in one or more embodiments. Additionally, it is intended that embodiments of the disclosed subject matter may and indeed cover variations and modifications of the described embodiments.

[0019] It is important to note that, unless the context explicitly specifies otherwise, the singular forms “a,” “an,” and “described” as used in the specification and appended claims include a plural of indicators. That is, unless otherwise explicitly stated, the words “a” and “an,” etc., as used herein, have the meaning of “one or more.” Furthermore, it is understood that terms such as “left,” “right,” “top,” “bottom,” “front,” “rear,” “side,” “height,” “length,” “width,” “upper,” “lower,” “inner,” “outer,” “internal,” “external,” etc., which may be used herein, describe reference points only and do not necessarily limit embodiments of the disclosed subject matter to any particular orientation or configuration. Additionally, terms such as “first,” “second,” and “third” identify only one of the various parts, components, reference points, operations, and / or functions described herein, and similarly do not necessarily limit embodiments of the disclosed subject matter to any particular configuration or orientation.

[0020] Throughout this disclosure, the term "groove" is used as a type of etched feature, and the two terms (groove and etched feature) are used interchangeably herein. Furthermore, the term "groove" is not limiting and can refer to holes, slits, slots, recesses, or other types of engraved patterns in the etched substrate material.

[0021] The inventors recognized that as the size of stacked structures increases, performing high aspect ratio (HAR) etching while minimizing the "bending" effect on the sidewalls of the recesses becomes increasingly difficult. For example, in 3D NAND, the stacked structure is formed by the deposition of alternating films (typically alternating SiO and SiN layers). This stack is somewhat analogous to a skyscraper with many layers, on which many memory cells are formed. Deep etching is required to define the channels between the cells, and ideally, the etching should have a uniform aperture size across all layers in the stack. If not performed correctly, non-uniformity in a particular aperture can manifest in various forms, including bending, such as... Figure 1Region 140 of the stack 100 is shown. The bending is a result of over-etching of the sidewalls, particularly in the upper part of the etched layer 120. The bending may be a result of ion scattering from the facet edges of the mask, which has been exposed to a considerable etching time. Although ions in the HAR are oriented in a highly linear manner, some ions bounce off the facet edges of the mask and are thus directed to the sidewalls in region 140. Additionally, as... Figure 1 As shown, a mask (amorphous carbon layer) 130 is disposed on an etched layer 120, which in turn is formed on a substrate 110. As a result of the resist mask facet angle, over-etching of the upper sidewalls of the etched layer 120 causes bending of the critical dimension (CD) of the recess, which in turn leads to non-uniformity of the critical dimension along the entire depth of the aperture. Therefore, this bending should be avoided to maintain the viability and performance consistency of the memory cells. In this discussion, CD refers to the diameter of the recess, but may also include the line of the recess and the gaps CD in the gap structure (groove).

[0022] Conventional apparatuses form grooves in a substrate through a repeatable deposition and etching process. This process begins with etching the substrate. Fluorine-containing gases are typically used in the etching step. In this application, the fluorine-containing gas may be, for example, C4F6, or C4F8. x F y The gas can be NF3 or SF6. However, a fluorine-containing gas can be any other gas that includes fluorine.

[0023] After the substrate etching is stopped, a protective film is formed on the sidewalls of the groove. Precursor adsorption and modification are repeated multiple times to form a protective film of the desired thickness. To ensure the protective film penetrates deep into the groove, a precursor with a low adhesion coefficient is used. Chemical reactants (e.g., malonyl chloride and ethylenediamine) can be used to form the protective film. After the protective film is deposited, etching continues, and this cycle is repeated until the groove is complete. In this application, the precursor may include, for example, an aminosilane or another silicon-containing (Si) component. For clarity, although Si is used as an exemplary precursor component in many places herein, it should be understood that precursor components other than Si are also intended as active precursor components adsorbed onto the substrate surface (e.g., sidewalls). Furthermore, this teaching is not intended to limit Si to the only precursor component.

[0024] The inventors recognize that conventional substrate processing techniques have certain limitations. Conventional techniques for etching substrates involve repeating deposition and etching steps until the grooves in the substrate are completed. Additionally, the deposition steps in conventional ALD or conventional subconformal ALD processes for suppressing bending in the sidewalls result in a thicker protective film in the upper region of the groove, which may reduce the size of the openings in the mask pattern (e.g., the openings become blocked).

[0025] To overcome the limitations of conventional technologies, the inventors have developed an apparatus and process for controlling (limiting) the amount of film deposited (the thickness distribution of the protective film) in the grooves during ALD processes or unsaturated (subconformal) ALD processes. By controlling (limiting) the amount of film deposited, the thickness of the protective film at the mask openings is suppressed compared to other portions of the grooves in the etched layer. Therefore, the mask openings are not blocked during or after the deposition of the protective film.

[0026] The inventors have recognized and developed a method for controlling the amount of film formed in a groove. In one embodiment, this method is implemented in a series of steps beginning with the adsorption of a first gas (also referred to as a precursor) onto the surface of a substrate. The precursor may be a silicon-containing (Si) gas and is supplied to a reaction chamber in which the substrate is placed. Specifically, a precursor component of the first gas, such as Si (the Si-containing gas component), is adsorbed onto the substrate surface. The first gas may be applied for a first time period.

[0027] Additionally, after adsorbing the precursor, a modified gas (also called a reactant gas) is introduced. The modified gas can be supplied to the groove. This modified gas (e.g., an oxygen-containing gas (e.g., O*-based)) is supplied to the reaction chamber. Plasma is generated from the modified gas, exposing the adsorbed precursor to the plasma to drive a surface reaction, thereby forming a protective film on the sidewalls of the groove. The oxygen-containing gas can include, but is not limited to, O2, CO, CO2, O3, etc. Alternatively, the modified gas can be a nitrogen-containing gas, such as NH3, N2, NF3, etc., but these examples are not limiting.

[0028] Alternatively, in the formation of a subconformal ALD, the precursor is adsorbed onto only a portion of the substrate surface. A modifying gas is then introduced, and a film is formed only in the portion where the precursor was adsorbed. Specifically, for example, the precursor can be supplied in a relatively short time, and the pressure and flow rate can be reduced relative to standard process times. The supply of the precursor and the modifying gas constitutes the first cycle of the mixed gas application cycle, and the result of supplying the modifying gas is the formation of a protective film on the sidewalls of the groove, while the bottom of the groove can be partially etched. In the case of using a Si-containing gas as the precursor and O* radicals as the modifying gas, the protective film formed on the sidewalls of the groove is SiO2.

[0029] The inventors have recognized that by providing inhibitors such as fluorine-containing gases during modification in ALD (and subconformal ALD) processes, the amount of film formed at the mask openings can be reduced, and clogging of the openings can be suppressed. Specifically, fluorine containing F gas adheres to the periphery of the mask openings and hinders the adsorption of precursors for subsequent process repetitions. Therefore, the thickness of the protective film can be gradually reduced along the sidewalls of the grooves, thereby reducing the amount of film formed at the mask openings and suppressing clogging at the openings.

[0030] Many advantageous effects have been achieved using the disclosed embodiments, and the inventors have recognized the advantages of the embodiments of this disclosure. One advantage is that a protective film with a controlled thickness can be formed on the sidewalls, while a thinner protective film can be formed on the mask. The protective film on the sidewalls can have a thickness that gradually decreases with depth on the sidewalls of the groove. This suppresses the reduction of the mask opening size and controls the distribution of the protective film thickness, resulting in improved etching quality. The protective film can be intentionally formed to be relatively thick in the areas where lateral etching occurs and relatively thin in other locations where lateral etching is not a problem. In addition, the diameter of the bottom of the groove can be widened by over-etching while suppressing the bending of the upper part of the groove.

[0031] Move to the attached diagram. Figure 2 A substrate processing system 200 according to the present disclosure is shown. The substrate processing system 200 includes a transfer device 240 (operating under reduced pressure relative to etching devices 252, 254, 256, and 258), comprising a transfer robot 242 for transferring a substrate W to and from the etching devices 252, 254, 256, and 258. The transfer device 240 has a vacuum transfer chamber interfaced with loading locking chambers 232 and 234. The etching devices 252, 254, 256, and 258 are connected to the transfer device 240 and are separate from the loading locking chambers 232 and 234.

[0032] Loading locking chambers 232 and 234 provide a way to divide the environment between the transfer device 240 and the loading device 220. The loading device 220 has a carrier placement stage for placing carriers. The carriers, for example, hold 25 substrates W, and are placed on the front surface of the loading device 220 when moving into and out of the substrate handling system 200. A loading robot 222 transfers substrates between the carrier placement stage and the loading locking chambers 232 and 234. Carriers are exchanged in corresponding loading ports 212-218.

[0033] In this example, controller 260 is a microcontroller, however... Figure 4 The computer (local dedicated computer or distributed computer) and / or processing circuitry described herein can be used as an alternative to controller circuitry configured by computer code to perform the control operations described herein.

[0034] Figure 3An etching apparatus 300 (e.g., a capacitively coupled plasma (CCP) system) is schematically shown connected to a transfer device via a gate valve. While a CCP system is shown as an example, any other etching apparatus (e.g., an inductively coupled plasma (ICP) device, etc.) may be used. The etching apparatus 300 includes a reaction chamber 310, approximately cylindrical in shape, and formed of, for example, aluminum. The reaction chamber 310 is connected to ground potential. A plasma-resistant film is formed on the inner wall surface of the reaction chamber 310, and may be a film formed by anodizing or a ceramic film (e.g., a film formed of yttrium oxide). When RF power is supplied to at least one of an upper electrode 330 and a base 320 (serving as a lower electrode for generating plasma in the reaction chamber 310), plasma 312 is formed between the upper electrode 330 and the base 320, whereby a substrate W is processed. Plasma 312 is formed close to the substrate W, and the substrate W is held on the upper surface of an electrostatic chuck 322, as will be discussed in more detail below. The base 320 has an approximately disk-shaped structure and is conductive.

[0035] Gas source 360 ​​includes multiple gas sources controlled by a series of corresponding flow controllers. Gas source 360 ​​supplies gas to reaction chamber 310 through one or more gas lines.

[0036] The etching apparatus 300 further includes a first RF power supply 340, which generates RF energy in the range of 27 MHz to 100 MHz (60 MHz is an exemplary frequency). The first RF power supply 340 is connected to the upper electrode 330 by a matching circuit that matches the output impedance of the first RF power supply 340 with the impedance of the upper electrode 330.

[0037] The etching apparatus 300 further includes a second RF power supply 350, which generates RF energy for biasing purposes to attract ions to the substrate W. The second RF power supply 350 operates at a lower frequency than the first RF power supply 340, typically in the range of 400 kHz to 13.56 kHz. In an alternative embodiment, multiple RF power supplies 340 and 350 may be coupled to the same electrode (lower electrode 320).

[0038] The upper electrode 330 has a second power source that serves as a variable direct current (DC) power supply 380. The variable DC power supply 380 can also be used as a DC bias for the RF energy applied to the upper electrode from the first RF power supply 340. The variability of the DC power supply 380 allows for operational control of the ion energy, making the etching rate controllable depending on the process being performed.

[0039] The RF energy generated by the RF power supply 350 can be pulsed. Etching primarily occurs when bias power is supplied to the base / lower electrode. Deposition primarily occurs when bias power is not supplied to the base / lower electrode. Pulsed bias allows for separation of the etching and deposition stages. Etching occurs after the formation of the protective film and protects the sidewalls of the groove from lateral erosion. Furthermore, variations in the pulse duty cycle (bias on-time / (bias on-time + bias off-time)) can control the etch / deposition balance. A longer bias off-time results in a thicker protective film, providing greater protection. A longer bias on-time increases the etching rate.

[0040] In an embodiment, the etching apparatus 300 may have an independent or integrated design with the controller 260. Figure 2 Dedicated control circuits for cooperative operation (e.g., such as) Figure 4 (Processing circuit in the memory). The controller 260 executes the control program stored in the memory and controls the components of the etching apparatus 300 based on the recipe data stored in the storage device.

[0041] The etching apparatus 300 includes an exhaust device 370 connected to the internal atmosphere of the reaction chamber 310. The exhaust device 370 includes a pressure controller (e.g., an automatic pressure control valve, a vacuum pump (e.g., a turbomolecular pump)) to controllably depressurize the reaction chamber 310 and exhaust gases from the reaction chamber 310.

[0042] Figure 4 This is a block diagram of the processing circuitry used to perform the computer-based operations described herein. Figure 4 The diagram illustrates a processing circuit 400 for controlling any computer-based and cloud-based control process. As those skilled in the art will understand, descriptions or blocks in the flowchart are to be understood as representing modules, segments, or coded portions that include one or more executable instructions for implementing specific logical functions or steps in the processing. Alternative implementations are included within the scope of exemplary embodiments of the invention, wherein, depending on the functionality involved, functions may not be performed in the order shown or discussed (including substantially simultaneous or reverse order). The various elements, features, and processes described herein can be used independently of each other or can be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of the invention.

[0043] exist Figure 4In this embodiment, the processing circuit 400 includes a CPU 401 that performs one or more of the control processes described above / below. Program data and instructions may be stored in memory 402. These processes and instructions may also be stored on a storage medium disk 404 (e.g., a hard disk drive (HDD)) or a portable storage medium, or may be stored remotely. Furthermore, the claimed invention is not limited to the form of a computer-readable medium storing instructions for the invention's processing. For example, instructions may be stored on a CD, DVD, flash memory, RAM, ROM, PROM, EPROM, EEPROM, hard disk, or any other information processing device (e.g., a server or computer) that communicates with the processing circuit 400. These processes may also be stored in network-based memory, cloud-based memory, or other remotely accessible memory and may be executed by the processing circuit 400.

[0044] Additionally, the claimed invention can be a component or combination thereof that executes in conjunction with a CPU 401 and an operating system (e.g., Microsoft Windows, UNIX, Solaris, LINUX, Apple MAC-OS, and other systems known to those skilled in the art).

[0045] The hardware components for implementing the processing circuit 400 can be implemented using various circuit elements. Furthermore, the functions of the above embodiments can be implemented by a circuit including one or more processing circuits. For example... Figure 4 As shown, the processing circuitry includes a dedicated, programmable processor (e.g., processor (CPU) 401). The processing circuitry also includes devices such as application-specific integrated circuits (ASICs) and conventional circuit components configured to perform the functions described.

[0046] exist Figure 4 In this embodiment, the processing circuit 400 includes a CPU 401 that performs one of the aforementioned processes. The processing circuit 400 can be a general-purpose computer or a specific special-purpose machine. In one embodiment, the processing circuit 400 becomes a specific special-purpose machine when the processor 401 is programmed to perform in-situ ESC replacement by controlling voltage and a robotic arm to replace the ESC without exposing the reaction chamber 310 to the external atmosphere. The processing circuit 400 can be in or communicate locally with the substrate processing device 200. In some embodiments, the processing circuit 400 can be located remotely from the substrate processing device 200, providing processing instructions to the substrate processing device 200 via a network 428.

[0047] Alternatively or additionally, as those skilled in the art will recognize, the CPU 401 may be implemented on an FPGA, ASIC, PLD, or using discrete logic circuitry. Furthermore, the CPU 401 may be configured to enable multiple processors to work collaboratively in parallel to execute instructions for the processes described above.

[0048] Figure 4 The processing circuitry 400 also includes a network controller 406 (e.g., an Intel Ethernet PRO network interface card from Intel Corporation, USA) for interfaced with network 428. It is understood that network 428 can be a public network (e.g., the Internet) or a private network (e.g., a LAN or WAN network) or any combination thereof, and may also include PSTN or ISDN subnetworks. Network 428 can also be wired (e.g., Ethernet) or wireless (e.g., a cellular network including EDGE, 3G, and 4G wireless cellular systems). The wireless network can also be Wi-Fi, Bluetooth, or any other known form of wireless communication.

[0049] The processing circuitry 400 also includes a display controller 408 (e.g., a graphics card or graphics adapter) for interfacing with a display 410 (e.g., a monitor). A general-purpose I / O interface 412 interfaces with a keyboard and / or mouse 414 and a touchscreen panel 416 on or separate from the display 410. The general-purpose I / O interface also connects to various peripheral devices 418, including printers and scanners.

[0050] The general-purpose storage controller 424 connects the storage medium disk 404 to the communication bus 426 (which may be ISA, EISA, VESA, PCI, etc.) for interconnecting all components of the processing circuitry 400. For the sake of brevity, descriptions of the general features and functions of the display 410, keyboard and / or mouse 414, display controller 408, storage controller 424, network controller 406, and general-purpose I / O interface 412 are omitted here because their features are known.

[0051] The exemplary circuit elements described in the context of this invention may be replaced by other elements and may be constructed differently from the examples provided herein. Furthermore, circuitry configured to perform the features described herein may be implemented in multiple circuit units (e.g., chips), or the features may be combined in circuitry on a single chipset.

[0052] The functions and features described herein can also be performed by various distributed components of the system. For example, one or more processors can perform the system functions, wherein the processors are distributed across multiple components communicating in a network. In addition to various human-machine interfaces and communication devices (e.g., display monitors, smartphones, tablets, personal digital assistants (PDAs)), the distributed components may also include one or more clients and servers that can share processing. The network can be a private network (e.g., a LAN or WAN) or a public network (e.g., the Internet). System input can be received via direct user input and can be received remotely in real time or as batch processing. Furthermore, some implementations may be performed on modules or hardware different from those described. Therefore, other implementations are within the scope of the claims.

[0053] Figure 5 A flowchart of an exemplary etching method according to the present invention. (Refer to...) Figures 6A to 6C discuss Figure 5 , Figures 6A to 6C The etched grooves are shown when using a protective film with a subconformal ALD.

[0054] The etching method begins at step 510, wherein a substrate having an etched layer 610 and a mask 620 disposed on the etched layer 610 is provided. The substrate having the etched layer 610 and the mask layer 620 may be a reference. Figure 2 and Figure 3 The substrate W under discussion. For example, the processing circuit 400 can control the transfer device 240 to transfer the substrate W to the etching system.

[0055] In step 520, the processing circuit 400 controls the etching system to partially etch the etch layer to form grooves in the etch layer 610 through openings in the mask 630. As discussed above with respect to plasma 312, plasma or other etching gases can be used for etching in this step. In step 520, known etching methods can be used. Plasma is generated from the etching gas, and an electrical bias is supplied to the substrate to extract ions from the plasma.

[0056] In step 530, the processing circuit 400 controls the etching apparatus 300 to form a protective film 640 on the sidewalls of the grooves in the etched layer 610. To form the protective film 640, precursor particles are first adsorbed onto the sidewall surfaces of the grooves in the etched layer 610. The precursor can be adsorbed by generating a plasma of precursor gas or without generating plasma. Then, the precursor particles are exposed to a modified gas to form the protective film 640.

[0057] The protective film 640 can be formed using either a conventional ALD-based process or a subconformal ALD process. See below for further details. Figures 9A to 9C The traditional ALD-based process is discussed.

[0058] The following are two aspects of the subconformal ALD process:

[0059] (1) The precursor can be adsorbed onto the entire surface of the substrate. The surface of the substrate includes the surface of the grooves (the sidewalls and bottom of the etched grooves). After the precursor is adsorbed, the supply of the modifying gas is controlled for a relatively short time. Due to this controlled supply of the modifying gas, for example, the O* radicals generated from the modifying gas become difficult to reach the lower and bottom parts of the grooves, thus fewer O* radicals reach the lower and bottom parts of the grooves.

[0060] (2) The precursor is adsorbed only on a portion of the substrate surface. The subsequently introduced modified gas forms a film only on the portion of the surface where the precursor is adsorbed. For example, the precursor can be supplied for a relatively short time, and the pressure and flow rate of the precursor can be reduced.

[0061] In the formation of the protective film 640, a precursor is supplied to the reaction chamber, and the precursor is adsorbed onto the sidewalls of the groove. After the precursor is adsorbed onto the groove, a modifying gas (e.g., O2) and an inhibitor gas are supplied to the reaction chamber. Precursor particles disposed on the substrate combine with the modifying gas supplied to the reaction chamber. In an exemplary embodiment, Si-containing precursor particles from the Si-containing precursor gas are disposed on the sidewalls and then combine with O* radicals from the modifying gas to form SiO by oxidizing the Si-containing precursor particles on the sidewalls. x Protective layer. This process can be repeated until a controlled thickness of the protective layer is achieved.

[0062] In some embodiments, the inhibitor gas and the modifying gas are provided during the modification phase of step 530 but not during the adsorption phase of step 530. In other embodiments, the inhibitor gas and the modifying gas are provided throughout step 530. When the inhibitor gas is a fluorinated gas, the fluorine from the fluorinated gas adheres to the periphery of the mask opening and hinders precursor adsorption for subsequent repetitions of the treatment. Therefore, the thickness of the protective film can gradually decrease along the sidewalls of the groove, thereby reducing the amount of film formed at the mask opening and suppressing clogging at the opening.

[0063] In some embodiments, an electrical bias may be supplied to the substrate in step 530. The electrical bias may be less than the electrical bias in etching steps 520 and 540. See below. Figures 7A to 7C Further details are discussed regarding the adsorption, modification, and purging stages of step 530 and the formation of the protective film 640.

[0064] By using the method having steps (1) or (2) above in step 530, when plasma is generated from the modified gas and the adsorbed precursor is exposed to the plasma to drive the surface reaction, the protective film 640 is formed with a thickness that gradually decreases downward on the sidewalls of the grooves in the etched layer 610. During the adsorption and / or modification phase, the supply of the fluorine inhibitor gas and the modified gas hinders the adsorption of the precursor at the mask opening.

[0065] The sequence of forming the protective film 640 in step 530 is repeated (cycle) until a controllable, predetermined thickness is obtained. Thus, the integrity of the critical dimensions of the groove is maintained with the help of the protective film on the sidewalls of the groove, thereby preventing sidewall bending (a problem associated with conventional etching processes).

[0066] After the protective film 640 is formed, the process proceeds to step 540, in which the substrate is further etched as in step 520.

[0067] In step 550, the processing circuit 400 determines whether an additional protective film 640 is needed to further protect the sidewalls before performing subsequent etching steps. The processing circuit 400 determines the need for the additional protective film 640 based on analysis of multiple test substrates processed according to the method (e.g., lateral or scanning electron microscopy, TEM, or SEM). Once multiple cycles achieving a predetermined thickness are identified, the process is recorded in a process menu used to program the processing circuit 400 to control the deposition / etching steps used to process the substrates in subsequent process batches.

[0068] If the amount of protective film 640 remaining on the sidewall is insufficient to protect the sidewall during subsequent etching steps (Yes in step 550), the process returns to step 530, where an additional protective film is formed on the sidewall. However, if it is determined in step 550 that the amount of protective film is sufficient to protect the sidewall during further etching until the final depth is reached (No in step 550), the process proceeds to step 560, where etching continues until the final depth is achieved.

[0069] The determination at step 550 can be performed by the processing circuit 400 according to the following process: the processing circuit 400 determines whether an additional iteration of the etching process is required based on whether a predetermined etching time is met. To this end, the processing circuit 400 can track the cumulative etching time of the etching performed in the step iterations of step 540 and compare the cumulative etching time with the predetermined etching time. Therefore, by tracking the cumulative etching time, the processing circuit 400 will know whether an additional etching step can be performed without further replenishing the protective film on the sidewalls of the groove.

[0070] In step 560, the process ends with further etching of the substrate etch layer 610 to a final depth. Therefore, steps 530, 540, and 550 are repeated a predetermined number of times, wherein the determination of step 550 may be based on the number of iterations performed under the same process conditions present when manufacturing the test substrate.

[0071] In one exemplary embodiment, the processing circuit 400 controls the execution of at least steps 520-560 within the reaction chamber 310. In another embodiment, the processing circuit 400 controls the formation of a protective film 640 in one reaction chamber and the performance of etching in another reaction chamber.

[0072] In another embodiment, the processing circuitry controls the initial etching to be performed in a first reaction chamber, and a further repeated etching to be performed in a second reaction chamber. The protective film can be formed in the first, second, or third reaction chamber.

[0073] In an exemplary embodiment of the present invention, during execution Figure 5 Following the process shown, after the protective film is formed, the critical dimension (CD) of the middle region of the sidewall in the vertical direction is smaller than the CD of the upper part of the sidewall. Additionally, in the etched layer, the thickness of the protective film formed on the upper part of the groove is less than the maximum thickness of the protective film formed on the sidewall of the groove.

[0074] In another exemplary embodiment of this disclosure, during execution Figure 5 Following the process shown, the CD of film deposition in the lower or middle portion of the groove sidewalls can be reduced by using different types of inhibitor gases. By changing the type of CxFy gas, the film deposition in the lower or middle portion of the etched groove sidewalls can be reduced.

[0075] Figures 6A to 6C It was shown that... Figure 5 The substrate used in the process shown. Specifically, Figure 6A The partial etching through the opening 630 of the mask 620 is shown for creating grooves in the etched layer 610.

[0076] Figure 6B A protective film 640 is shown formed on the sidewall of a groove in the etched layer 610. The protective film 640 is generated by the following steps: (1) adsorbing precursor particles onto the sidewall surface of the groove in the etched layer 610, (2) purging the gas in the reaction chamber, (3) converting the precursor into a protective film by supplying a modifying gas and an inhibitor gas, and (4) purging the gas in the reaction chamber again. The precursor particles are adsorbed by generating plasma of the precursor gas or without generating plasma. Purging the gas in the reaction chamber may be an optional step.

[0077] Figure 6CFurther etching through opening 630 of mask 620 is shown to create grooves in etched layer 610. Due to the formation of protective film 640, Figure 6C The grooves in the design do not result in a curved shape because they reduce lateral etching.

[0078] For reference Figure 5 The protective film 640 can be repeatedly formed and the substrate further etched until the final depth of the groove within the etched layer 610 is obtained.

[0079] There are no limitations on the material of the etched layer 610. For example, the etched layer 610 may include a silicon-containing film, such as SiO2. x Or a Si-containing dielectric film of SiN. Examples of Si-containing dielectric films may include alternating layers of SiO2. x Layers of SiN (ONON stack) and alternating layers of SiO x And a layer of polysilicon (OPOP stack). The etched layer 610 may also include an organic film. The aspect ratio of the groove can be 10 to 20 or more, or 30 or more.

[0080] The table below lists some combinations of materials for the etching layer, mask, and etching gas:

[0081]

[0082] However, there are no material limitations for the etched layer, mask, and main etch gas.

[0083] In another exemplary embodiment of this disclosure, the etch layer 610 (e.g., an organic film) can be etched by plasma generated from oxygen-containing gas during the formation of the protective film 640.

[0084] Figures 7A to 7C An exemplary timing diagram is shown for forming a protective film.

[0085] Figure 7A The first timing diagram illustrates that a precursor is applied to the substrate before the application of RF power, fluorine-containing gas, and oxygen-containing gas. Specifically, during the adsorption period A, the precursor is adsorbed onto the surface of the substrate. After the adsorption period is complete, the supply of the precursor ends, and fluorine-containing gas and oxygen-containing gas are supplied during the modification period M. Specifically, during the modification period M (in step 530), a protective film is formed through a surface reaction between the precursor layer and the plasma of the modifying gas, and an inhibitor is formed at the upper end of the pattern (near the mask opening) by a gas inhibitor (e.g., plasma from the fluorine-containing gas). Therefore, the precursor in subsequent cycles is hardly adsorbed onto the upper end of the pattern (near the mask opening), resulting in reduced film formation at the upper end of the pattern.

[0086] The supply of RF is synchronized with the supply of oxygen-containing gas and fluorine-containing gas. After the modification period is completed, a new adsorption period A can begin. The adsorption period and modification period can be repeated multiple times in an alternating manner.

[0087] Purging inside the chamber can be performed between and / or after adsorption and modification.

[0088] In some embodiments, RF can be provided during both the adsorption period and the modification period, depending on the type of precursor used during the adsorption step.

[0089] Figure 7B A second timing diagram is shown, in which fluorinated and oxygen-containing gases are continuously supplied during both the adsorption and modification periods. Specifically, fluorinated and oxygen-containing gases are supplied at the beginning of the adsorption period when the precursor is adsorbed onto the substrate surface. When RF is supplied, fluorinated and oxygen-containing gases are continuously supplied throughout the adsorption period and then throughout the modification period. The adsorption and modification periods can be alternated multiple times, with fluorinated and oxygen-containing gases continuously supplied throughout the process.

[0090] In another exemplary embodiment, fluorine-containing gas or oxygen-containing gas can be supplied intermittently while RF is being supplied.

[0091] Purging inside the chamber can be performed between adsorption and modification and / or after modification.

[0092] Figure 7C A third timing diagram of an exemplary process is shown, wherein purging is performed between and after the adsorption and modification periods. In this exemplary process, the reaction chamber may be maintained at a chamber pressure of 10 mTorr during the formation of the protective film. This chamber pressure is exemplary, and the chamber pressure may be maintained at other static or dynamic pressures.

[0093] like Figure 7C As shown, the precursor is initially applied during the adsorption period. In this exemplary process, the precursor can be an aminosilane supplied at 20 sccm, with an adsorption period of 2 seconds. However, the precursor can be other material combinations and supplied at different flow rates. Moreover, the adsorption period can last for different durations.

[0094] At the start of the adsorption period, fluorine-containing gas and oxygen-containing gas are also supplied. A continuous supply of fluorine-containing gas and oxygen-containing gas is provided. In this exemplary process, fluorine-containing gas (e.g., CF4) is continuously supplied at 100 sccm, and oxygen-containing gas (O2 gas) is continuously supplied at 300 sccm. However, other forms of fluorine-containing gas and oxygen-containing gas can be supplied at different flow rates.

[0095] At the end of the adsorption period, a first purging period is performed to purge the reaction chamber containing fluorine and oxygen gases. In an exemplary process, the first purging period has a length of 1.5 seconds. However, the first purging period can last for varying durations. The supply of fluorine and oxygen gases can be provided continuously throughout the first purging period. Alternatively, the supply of fluorine and oxygen gases can be paused at the beginning of the first purging period and restarted at the end of the first purging period.

[0096] At the end of the first purging period, a modification period for providing RF power is performed. Fluorine-containing gas and oxygen-containing gas are continuously supplied throughout the modification period. In this exemplary process, the modification period has a length of 1 second. However, the modification period can last for different durations. In this exemplary process, RF power can be provided as a continuous wave of 60 MHz or as a pulsed wave of 20 kHz. However, other RF power values, waveforms, and frequencies can be used.

[0097] At the end of the modification period, a second purging period is performed to purge the reaction chamber containing fluorinated and oxygen gases. In the exemplary process, the second purging period has a length of 1 second. However, the second purging period can last for varying durations. The supply of fluorinated and oxygen gases can be provided continuously throughout the second purging period. Alternatively, the supply of fluorinated and oxygen gases can be paused at the beginning of the second purging period and restarted at the end of the second purging period.

[0098] At the end of the second purge period, the cycle can restart in the next adsorption period. Cycles of the exemplary process can be performed until a controlled thickness of the protective film is achieved. In one example, 50 cycles of adsorption / first purge / modification / second purge can be performed to achieve a controlled thickness of the protective film.

[0099] Figure 8 The effect of embodiments of this disclosure on the CD of the sidewall at the mask opening is illustrated. Specifically, Figure 8 The depth Z of the groove is shown relative to the CD of the groove (measured in nm). (Measured in μm from the mask surface to the bottom of the groove with 0 being the opening of the mask). Figure 8 Data from an etched (“initial”) substrate, a reference (“reference”) substrate under a conventional subconformal ALD process, and a substrate under a subconformal ALD process according to this disclosure (wherein CF4 (“w / CF4”) is provided throughout the formation of the protective film) are also shown.

[0100] like Figure 8 As shown, for the applied subconformal ALD process, the CD of the sidewalls changes at different rates as the opening of the mask approaches (depth close to 0).

[0101] The initial substrate is the substrate in a state after etching with fluorocarbon gases and before performing subconformal ALD deposition.

[0102] In the reference substrate, the CD decreases from the middle to the top of the sidewalls as the mask opening approaches (-0.5 μm to 0 μm). This is due to the increased thickness of the protective film caused by the conventional subconformal ALD process.

[0103] In contrast, when CF4 is supplied during the subconformal ALD process according to this disclosure, the CD (w / CF4) of the groove continuously increases from the middle to the top of the sidewall as it approaches the opening of the mask (-0.5 μm to 0 μm).

[0104] Therefore, as Figure 8 As shown, applying a subconformal ALD process with CF4 supplied throughout allows for the formation of a protective film on the mask with a controlled reduction in thickness. By adding CF4 to the ALD (subconformal ALD) process, the amount of film formed at the mask openings can be reduced, thus suppressing opening blockage compared to a reference subconformal ALD process that never provides a fluorinated gas (e.g., CF4).

[0105] Specifically, a thicker film is formed on areas prone to lateral etching (e.g., directly below the mask), while a thinner film is formed on the mask itself. This suppresses the reduction of the mask opening and controls the film thickness distribution, thereby improving the shape of the groove.

[0106] Furthermore, the present invention provides an etching technique in which the film is formed to be thicker in areas where lateral etching may occur and thinner in other areas (e.g., the bottom of the mask and / or the groove). Additionally, in the subconformal ALD process according to this disclosure, the diameter of the bottom of the groove can be widened by over-etching while suppressing groove bending caused by lateral etching.

[0107] Figures 9A to 9C Another embodiment of this disclosure is shown, wherein a protective film is formed on the bottom surface of a groove in an etched layer. Figure 5 A variation of the process shown can be used to form Figures 9A to 9C The groove shown.

[0108] Specifically, in step 510, a substrate having an etched layer 910 and a mask 920 disposed on the etched layer 910 is provided. In step 520, the processing circuit 400 controls the etching apparatus 300 to partially etch the etched layer 910 through the opening of the mask 930.

[0109] In step 530, the processing circuit 400 controls the etching apparatus 300 to form a protective film 940 on the substrate. In this case, the processing circuit 400 controls the etching apparatus 300 to form the protective film 940 on the sidewalls of the etched layer 910 and the bottom surface of the groove. In step 540, the substrate is further etched as in step 520 to etch through the bottom surface of the protective film and to further etch the etched layer 910 to increase the depth of the etched layer. In step 550, the processing circuit 400 determines whether an additional protective film 940 is needed to satisfactorily protect the sidewalls of the groove. As the inventors recognize, the presence of the protective layer effectively protects the sidewalls of the groove in the silicon-containing layer from being removed by ions with relatively low energy. On the other hand, ions incident on the bottom of the groove have higher energy, so the bottom of the groove can be removed (etched) even when a protective layer is formed at the bottom of the groove. Therefore, because the protective layer has sufficient chemical strength to prevent removal by low-energy ions that are side-bombed on the sidewalls, it preferably protects against unwanted sidewall etching, while the energy of the higher ions that bombard the bottom of the groove is high enough to etch through the protective layer to the bottom of the groove. Furthermore, this allows for etching of grooves with higher aspect ratios while suppressing sidewall bending.

[0110] If an additional protective film 640 is required ("Yes" in step 550), the process returns to step 530. If an additional protective film 640 is not required ("No" in step 550), the process proceeds to step 560. In step 560, the process ends with further etching of the substrate's etch layer 910 to the final depth.

[0111] As referenced above Figure 5 and Figures 6A to 6C The protective film 940 discussed is generated by the following steps: (1) adsorbing the precursor onto the sidewall and bottom surfaces of the groove in the etched layer 910, (2) purging the gas in the reaction chamber, (3) converting the precursor into the protective film, and (4) purging the gas in the reaction chamber again. The precursor can be adsorbed by generating plasma of the precursor gas or without generating plasma. Purging the gas in the reaction chamber can be an optional step. Alternatively, the inhibitor gas and the modifying gas can be continuously applied during purging, or the process can be stopped before purging and then restarted after purging. In another example, in a subconformal ALD or ALD, after the precursor is adsorbed, plasma can be generated from the modifying gas (e.g., oxygen-containing gas), and modification can be performed. The inhibitor gas can then be supplied to form the plasma, and the plasma can be exposed to the substrate.

[0112] exist Figures 9A to 9C In an exemplary embodiment of the formation of the protective film 940, the precursor supply time and / or modification time are compared with the reference time. Figures 6A to 6CThe precursor supply time and / or modification time in the subconformal ALD process described in the formation of the protective film 640 are long.

[0113] Embodiments of the invention have now been described, and those skilled in the art will understand that the above is illustrative rather than restrictive, and is therefore presented only as examples. Thus, although specific configurations have been discussed herein, other configurations may also be employed. Many variations and other implementations (e.g., combinations, rearrangements, etc.) can be implemented by the invention and are considered to fall within the scope of the disclosed subject matter and any equivalents thereof, to those skilled in the art. Within the scope of the invention, features of the disclosed embodiments may be combined, rearranged, omitted, etc., to generate other implementations. Furthermore, certain features may sometimes be used advantageously without correspondingly using other features. Therefore, the application is intended to include all such substitutions, variations, equivalents, and changes within the spirit and scope of the disclosed subject matter.

[0114] Element reference labels

[0115] W substrate

[0116] 100 substrate

[0117] 110. Bottom layer (basic level)

[0118] 120 Etching Layer

[0119] 130 mask

[0120] 140° Bending (lateral erosion)

[0121] 200 Substrate Processing Device

[0122] Loading ports 212, 214, 216, and 218

[0123] 220 Loader

[0124] 222 Loading Robot

[0125] 232, 234 Loading Locking Chamber

[0126] 240 Conveyor Device

[0127] 242 Teleportation Robots

[0128] Etching systems 252, 254, 256, 300

[0129] 258 Storage Container / Converter

[0130] 260 controller

[0131] 310 Reaction Chamber

[0132] 312 Base

[0133] 320 Upper Electrode

[0134] 322 Electrostatic Chuck

[0135] 330 Upper Electrode

[0136] 340 RF power supply

[0137] 350 RF power supply

[0138] 360 Gas Source

[0139] 370 Exhaust System

[0140] 380 DC power supply

[0141] 400 processing circuit

[0142] 401 CPU

[0143] 402 Memory

[0144] 404 disk

[0145] 406 Network Controller

[0146] 408 Display Controller

[0147] 410 Monitor

[0148] 412 I / O Interface

[0149] 414 Keyboard / Mouse

[0150] 416 Touchscreen

[0151] 418 Peripheral Equipment

[0152] 424 Storage Controller

[0153] 426 Communication Bus

[0154] 428 Network

[0155] 610 Etching Layer

[0156] 620 mask

[0157] 630 Mask opening

[0158] 640 protective film

[0159] 910 Etching Layer

[0160] 920 mask

[0161] 930 Mask opening

[0162] 940 protective film

Claims

1. A method for forming a film on a substrate, the substrate comprising an etched layer and a mask formed on the etched layer, the method comprising: Step (a): In a reaction chamber, the substrate is exposed to a precursor to dispose precursor particles on at least the sidewalls of the grooves in the etched layer, wherein the precursor is a Si-containing gas; Step (b): An inhibitor gas and a modifying gas are supplied to the reaction chamber to generate plasma, wherein the inhibitor gas is a gas that hinders the adsorption of the precursor; and Step (c): When the inhibitor gas and the modifying gas are supplied in the reaction chamber, the precursor particles on the sidewall are modified into a protective film.

2. The method according to claim 1, further comprising: Step (d): After modification step (c), the substrate is etched with the plasma.

3. The method according to claim 1, wherein, Throughout the exposure step (a) and the modification step (c), the supply step (b) of the inhibitor gas and the modification gas is performed continuously.

4. The method according to claim 1, wherein, After completing the modification step (c), repeat the exposure step (a).

5. The method according to claim 1, wherein: Step (a) of exposing the substrate to the precursor is performed to additionally deposit precursor particles on the bottom surface of the grooves in the etched layer, and The modification step (c) includes: modifying the precursor particles on the bottom surface of the groove into the protective film.

6. The method according to claim 1, wherein, The inhibitor gas is CxFy gas.

7. The method according to claim 6, wherein, The thickness of the protective film formed on the upper part of the groove is less than the thickness of the protective film formed on the upper part of the groove when the CxFy gas is not supplied.

8. The method according to claim 1, wherein, After the protective film is formed, the critical dimension (CD) of the middle region of the sidewall in the vertical direction is smaller than the CD of the upper part of the sidewall.

9. The method according to claim 1, wherein, The thickness of the protective film formed on the upper part of the groove is less than the maximum thickness of the protective film formed on the sidewall.

10. The method according to claim 1, wherein, The modified gas and the inhibitor gas are supplied continuously.

11. The method according to claim 1, further comprising: Step (e): Purge the interior of the reaction chamber.

12. The method according to claim 11, wherein, The purging step (e) is performed after the exposure step (a), and then the purging step (e) is performed again after the modification step (c).

13. The method according to claim 2, wherein, Etching step (d) includes: A bias power is applied to the electrodes in the reaction chamber.

14. The method according to claim 1, wherein, Modification step (c) includes: During the modification in step (c), radio frequency (RF) is supplied to the electrodes in the reaction chamber.

15. A method of forming a film on a substrate, the substrate comprising an etched layer and a mask formed on the etched layer, the method comprising: During the first time period: Step (a): In a reaction chamber, the substrate is exposed to a precursor to deposit precursor particles on at least the sidewalls of the grooves in the etched layer, wherein the precursor is a Si-containing gas; and During the second time period: Step (b): An inhibitor gas and a modifying gas are supplied to the reaction chamber to generate plasma, wherein the inhibitor gas is a gas that hinders the adsorption of the precursor; and Step (c): When the inhibitor gas and the modifying gas are supplied in the reaction chamber, the precursor particles on the sidewall are modified into a protective film.

16. The method according to claim 15, wherein, At least a portion of the supply step (b) and the modification step (c) are performed simultaneously during the second time period.

17. The method of claim 15, further comprising: Radio frequency (RF) is provided in modification step (c).

18. An apparatus for forming a film on a substrate, the substrate including an etched layer and a mask formed on the etched layer, the apparatus comprising: The processing circuit is configured as follows: The precursor is controlled to be supplied to the reaction chamber, thereby exposing the substrate to provide precursor particles on at least the sidewalls of the grooves in the etched layer, wherein the precursor is a Si-containing gas; A controlled gas source supplies inhibitor gas and modified gas to the reaction chamber to generate plasma, wherein the inhibitor gas is a gas that hinders the adsorption of the precursor; and A radio frequency (RF) source is controlled to provide RF to modify precursor particles on the sidewalls into a protective film on the sidewalls of the grooves when the inhibitor gas and the modifying gas are supplied in the reaction chamber.

19. The apparatus according to claim 18, wherein, Throughout the process of providing the precursor and modifying the precursor particles into the protective film, the inhibitor gas and the modifying gas are continuously supplied.

20. The apparatus according to claim 18, wherein, The processing circuit is also configured to control exhaust to purge the inhibitor gas and the modified gas from the reaction chamber.

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