Double-pressure oxidation method for forming an oxide layer on a feature

Abstract

The present invention provides a method, apparatus, and medium for oxidizing features formed on a half-dimensional device structure. [Solution] Suitable for use in semiconductor manufacturing. The oxide layer is formed by exposing the substrate to both high-pressure oxidizing agent exposure and low-pressure oxygen-containing plasma exposure. High-pressure oxidizing agent exposure is performed at a pressure exceeding 10 Torr, and low-pressure oxygen-containing plasma exposure is performed at a pressure of less than approximately 10 Torr. Features are high aspect ratio trenches or holes in a stack of silicon oxide and silicon nitride layers.

Description

Technical Field

[0001]

[0001] Embodiments of the present disclosure generally relate to apparatuses for semiconductor device manufacturing, and more particularly, to methods for oxidizing features formed in a three-dimensional device structure.

Background Art

[0002]

[0002] The manufacture of silicon integrated circuits has imposed difficult requirements on the manufacturing process in order to increase the number of devices while reducing the minimum feature size on the chip. These requirements extend to manufacturing steps including depositing layers of different materials on difficult topologies and further etching features within those layers. The manufacturing process for next-generation NAND flash memories includes particularly difficult device shape dimensions and scales. NAND is a type of non-volatile storage technology that does not require power to retain data. To increase the memory capacity within the same physical space, three-dimensional NAND (3D NAND) designs have been developed. In such designs, alternating oxide and nitride layers are typically introduced, which are etched after being deposited on a substrate to form a structure having one or more surfaces extending substantially perpendicular to the substrate. One structure may have over 100 such layers. Such designs may also include high aspect ratio (HAR) structures with an aspect ratio of 30:1 or greater.

[0003]

[0003] HAR structures are often coated with silicon nitride (SiNx), amorphous silicon, or polysilicon layers. It is difficult to conformally oxidize such structures to form an oxide layer of uniform thickness. Uniform oxidation of each structure becomes increasingly difficult as the aspect ratio increases, such as HAR structures having an aspect ratio exceeding 50:1 or exceeding 70:1.

[0004]

The invention's summary

Summary of the Invention

[0005]

[0005] The present disclosure relates, in general terms, to a method and apparatus for growing a layer on a substrate. In one embodiment, a method for processing a substrate is described. The method is suitable for use in semiconductor manufacturing. The method includes exposing the substrate to an oxidizing agent at a first pressure greater than about 20 Torr. After exposing the substrate to the oxidizing agent at the first pressure, the pressure around the substrate is reduced from the first pressure to a second pressure of less than about 10 Torr. After reducing the pressure to the second pressure, the substrate is exposed to an oxygen-containing plasma while the pressure around the substrate is at the second pressure.

[0006]

[0006] In another embodiment, another method for processing a substrate suitable for use in semiconductor manufacturing is described. This method involves exposing a plurality of features having nitride walls to an oxidizing agent at a first pressure greater than about 50 Torr in order to form an oxide layer on the nitride walls of the substrate. After exposing the plurality of features to the oxidizing agent at the first pressure, the pressure around the substrate is reduced from the first pressure to a second pressure of less than about 5 Torr. After reducing the pressure to the second pressure, the substrate is exposed to an oxygen-containing plasma while the pressure around the substrate is at the second pressure in order to increase the thickness of the oxide layer.

[0007]

[0007] In yet another embodiment, a non-transient computer-readable medium is described. The non-transient computer-readable medium stores instructions suitable for use in semiconductor manufacturing. When the instructions are executed by the processor, the computer system performs several steps. The steps include exposing the substrate to an oxidizing agent at a first pressure greater than about 20 Torr. After exposing the substrate to the oxidizing agent, the pressure around the substrate is reduced from the first pressure to a second pressure of less than about 10 Torr. After reducing the pressure to the second pressure, the substrate is exposed to an oxygen-containing plasma while the pressure around the substrate is at the second pressure.

[0008]

[0008] In order to understand the features of the present disclosure described above in detail, the present disclosure summarized above will be described more specifically with reference to embodiments illustrated in part in the accompanying drawings. However, it should be noted that the accompanying drawings are merely illustrative embodiments and should not be considered limiting in scope, and the present disclosure may also permit other equally valid embodiments. [Brief explanation of the drawing]

[0009] [Figure 1A] This is a schematic cross-sectional side view of a first process system according to an embodiment described herein. [Figure 1B] This is a schematic cross-sectional plan view of the first process system in Figure 1A according to the embodiment described herein. [Figure 2A] This is a schematic cross-sectional plan view of a second process system according to an embodiment described herein. [Figure 2B] This is a schematic cross-sectional plan view of a third process system according to an embodiment described herein. [Figure 3] This is a schematic cross-sectional side view of a fourth process system according to an embodiment described herein. [Figure 4] This is a schematic cross-sectional side view of a fifth process system according to an embodiment described herein. [Figure 5] Figures A to C are schematic cross-sectional side views of a device stack in a forming method according to the embodiments described herein. [Figure 6] This is a flowchart illustrating the formation method of Figures 5A to 5C according to the embodiments described herein. [Figure 7] This graph shows the oxide growth rate on a device stack under various pressures and gas mixtures. [Modes for carrying out the invention]

[0010]

[0018] For ease of understanding, the same reference numerals are used to indicate identical elements common to the drawings whenever possible. It is assumed that elements and features of one embodiment can be usefully incorporated into other embodiments without further detail.

[0011]

[0019] This disclosure relates, in general, to a method and apparatus for conformally oxidizing high aspect ratio structures within a device stack. The method involves the use of high-pressure exposure of a substrate to an oxidizing agent. High-pressure exposure of the substrate to the oxidizing agent causes an oxide layer to form on a silicon nitride, amorphous silicon, or polysilicon layer within a high aspect ratio trench. The oxide layer is a conformal oxide layer having 95% or more conformality. The oxide layer grows to a thickness of about 2 nm to about 3 nm during high-pressure exposure of the substrate. Since the oxide layer grows from the silicon nitride layer, amorphous silicon layer, or polysilicon layer, a portion of the silicon nitride layer, amorphous silicon layer, or polysilicon layer is oxidized.

[0012]

[0020] After exposing the substrate to an oxidizing agent under high pressure, the pressure around the substrate is reduced. This reduced pressure allows for the formation of an oxygen radical-containing plasma. The oxygen radical-containing plasma also promotes the growth of an oxide layer on the silicon nitride layer. The oxide layer formed during high-pressure exposure serves as the underlayer, and the oxide layer grows during exposure to the oxygen radical-containing plasma. The oxide layer grows uniformly because the previously formed oxide layer reduces the flow rate of the oxidizing agent to the shallow parts of each high-aspect-ratio structure. The thickness of the oxide layer grows to over approximately 5 nm, for example, over approximately 6 nm, for example, from approximately 6 nm to approximately 8 nm during exposure to the oxygen radical-containing plasma. The conformality of the oxide layer after completion of exposure to the oxygen radical-containing plasma is still over 95%.

[0013]

[0021] Exposure to a high-pressure oxidizing agent allows more species to reach the bottom of high-aspect-ratio features on the substrate, enabling the formation of conformal layers. However, high-pressure oxidizing agents grow slowly on amorphous silicon, polysilicon, and silicon nitride. Therefore, a second oxidizing agent exposure using an oxygen radical-containing plasma is used to accelerate the growth rate of the oxide layer and shorten the oxidation time to achieve the target thickness. To increase the thickness of the oxide layer, exposure to the oxygen radical-containing plasma can be repeated or extended.

[0014]

[0022] High-pressure oxide exposure and oxygen radical-containing plasma exposure can be performed in either the same or different process systems. Performing both process steps within a single process system can potentially improve throughput and reduce overall costs. However, performing both high-pressure and plasma-containing processes within the same process system can be challenging depending on the process chamber architecture. This specification describes an improved process system that enables the performance of both high-pressure and plasma-containing processes within the same process area.

[0015]

[0023] In other embodiments, the substrate is moved between two or more process systems such that a first process system performs a high-pressure process and a second process system performs a plasma-containing process. Multiple process system types can be utilized as described herein. The processes described herein can be performed during the manufacturing of 3D NAND structures.

[0016]

[0024] FIG. 1A is a cross-sectional view of a first process system 100 according to an embodiment described herein. The first process system 100 includes a process chamber 102 and a remote plasma source 104. The process chamber 102 may be a rapid thermal processing (RTP) chamber. The remote plasma source 104 may be any suitable remote plasma source, such as a microwave-coupled plasma source operable at, for example, about 6 kW of power. The remote plasma source 104 is coupled to the process chamber 102 such that the plasma formed in the remote plasma source 104 flows toward the process chamber 102. The remote plasma source 104 is coupled to the process chamber 102 via a connector 106. Radicals formed in the remote plasma source 104 flow into the process chamber 102 through the connector 106 during processing of the substrate.

[0017]

[0025] The remote plasma source 104 includes a body 108 surrounding a tube 110 in which plasma is generated. The tube 110 may be made of quartz or sapphire. The body 108 includes a first end 114 coupled to an inlet 112, and one or more gas sources 118 may be coupled to the inlet 112 to introduce one or more gases into the remote plasma source 104. In one embodiment, the one or more gas sources 118 include an oxygen-containing gas source, and the one or more gases include an oxygen-containing gas. The body 108 includes a second end 116 opposite the first end 114, and the second end 116 is coupled to the connector 106. A coupling liner (not shown) may be disposed within the body 108 at the second end 116. A power source 120 (e.g., an RF power source) for supplying power to the remote plasma source 104 to facilitate plasma formation may be coupled to the remote plasma source 104 via a matching network 122. Radicals in the plasma are flowed through the connector 106 into the process chamber 102.

[0018]

[0026] The process chamber 102 includes a chamber body 125, a substrate support 128, and a window assembly 130. The chamber body 125 includes a first side surface 124 and a second side surface 126 opposite the first side surface 124. In some embodiments, a lamp assembly 132 surrounded by an upper sidewall 134 is positioned above and coupled to the window assembly 130. The lamp assembly 132 may include a plurality of lamps 136 and a plurality of tubes 138, and each lamp 136 may be disposed in a corresponding tube 138. The window assembly 130 may include a plurality of light pipes 140, and each light pipe 140 may be aligned with a corresponding tube 138 such that thermal energy generated by the plurality of lamps 136 can reach a substrate disposed in the process chamber 102. In some embodiments, a vacuum can be created in the plurality of light pipes 140 by applying a vacuum to an exhaust port 144 fluidly coupled to the plurality of light pipes 140. The window assembly 130 may have a conduit 143 formed therein for circulating a cooling fluid therethrough.

[0019]

[0027] The processing region 146 may be defined by the chamber body 125, the substrate support 128, and the window assembly 130. A substrate 142 is disposed within the processing region 146 and supported by a support ring 148 above a reflector plate 150. The support ring 148 may be attached to a rotatable cylinder 152 to facilitate rotation of the substrate 142. The cylinder 152 can be levitated and rotated by a magnetic levitation system (not shown). The reflector plate 150 reflects energy to the back side of the substrate 142 to promote uniform heating of the substrate 142 and improve the energy efficiency of the first process system 100. To facilitate monitoring of the temperature of the substrate 142, a plurality of optical fiber probes 154 may be disposed through the substrate support 128 and the reflector plate 150.

[0020]

[0028] A liner assembly 156 is positioned on the first side surface 124 of the chamber body 125 so that radicals flow from the remote plasma source 104 to the processing area 146 of the process chamber 102. The liner assembly 156 may be made of an oxidation-resistant material such as quartz to reduce interaction with process gases such as oxygen radicals. The liner assembly 156 is designed to reduce the narrowing of the radical flow into the process chamber 102. The liner assembly 156 is described in detail below. The process chamber 102 further includes a dispersed pumping structure 133 formed on the substrate support portion 128 adjacent to the second side surface 126 of the chamber body 125 to regulate the flow of radicals from the liner assembly 156 to the pumping port. The dispersed pumping structure 133 is located adjacent to the second side surface 126 of the chamber body 125.

[0021]

[0029] The opening 158 is positioned to penetrate the second side surface 126 of the chamber body 125. The opening 158 is configured for a substrate to pass through. The opening 158 may be positioned adjacent to a transfer chamber or other process system.

[0022]

[0030] The controller 180 can be coupled to various components of the first process system 100, such as the process chamber 102 and / or the remote plasma source 104, and can control their operation. The controller 180 generally includes a central processing unit (CPU) 182, memory 186, and support circuits 184 for the CPU 182. The controller 180 can directly control the first process system 100, or it can be controlled via other computers or controllers (not shown) associated with specific support system components. The controller 180 may be one of any form of general-purpose computer processor that can be used in an industrial environment to control various chambers and subprocessors. The memory 186, or computer-readable medium, may be one or more readily available memories such as random access memory (RAM), read-only memory (ROM), floppy disks, hard disks, flash drives, or any other form of local or remote digital storage. The support circuits 184 are coupled to the CPU 182 to support the processor in a conventional manner. The support circuits 184 include caches, power supplies, clock circuits, input / output circuits, and subsystems, etc. The processing operations may be stored in memory 186 as software routines 188 that can be executed or invoked to transform the controller 180 into a purpose-specific controller that controls the operation of the first process system 100. The controller 180 may be configured to perform any of the methods described herein.

[0023]

[0031] Figure 1B is a schematic cross-sectional plan view of the first process system 100 shown in Figure 1A. The first process system 100 includes both a remote plasma source 104 and a gas injector 192. The liner assemblies 156 of the remote plasma source 104 and the gas injector 192 are positioned at different points along the perimeter of the processing area 146. By including both the remote plasma source 104 and the gas injector 192, which are positioned through the same chamber body 125 and connected to the same processing area 146, it becomes possible to perform both high-pressure oxidation and low-pressure plasma processes within the same processing area 146.

[0024]

[0032] One or more exhaust passages 196a, 196b are located adjacent to and / or within the opening 158. One or more exhaust passages 196a, 196b are exhaust ports and are configured to exhaust gas and / or plasma from the processing area 146. One or more exhaust passages 196a, 196b are coupled to one or more exhaust pumps (not shown) to remove exhaust gas and / or plasma from the processing area 146. One or more exhaust passages 196a, 196b include at least a first exhaust passage 196a and a second exhaust passage 196b. The first exhaust passage 196a is located on the first side of the opening 158, and the second exhaust passage 196b is located on the opposite side of the opening 158. By utilizing the two exhaust passages 196a, 196b located on opposite sides of the opening 158, it is possible to more evenly discharge the process gas and plasma during processing.

[0025]

[0033] The gas injector 192 is positioned to penetrate the wall of the chamber body 125. The gas injector 192 includes a number of gas passages 194 that are fluidly connected to the processing area 146, passing through it. The gas injector 192 is configured to inject process gas into the processing area 146 and across the entire upper surface of the substrate 142. Each of the gas injector 192 and the gas passages 194 located within it is coupled to a process gas source 178. The process gas source 178 is configured to supply one or more oxidizers. One or more oxidizers include hydrogen (H2), oxygen (O2), ozone (O3), nitrous oxide (N2O), water / water vapor (H2O), hydrogen peroxide (H2O2), or hydroxide (OH) - ) containing one or a mixture thereof.

[0026]

[0034] The center of the gas injector 192 may be positioned at a first angle θ1 with respect to the center of the liner assembly 156 of the remote plasma source 104. The first angle θ1 is approximately 45 to 135 degrees, for example, approximately 60 to 120 degrees, for example, approximately 75 to 105 degrees. In some embodiments, the first angle θ1 is approximately 90 degrees such that the gas injector 192 and the liner assembly 156 of the remote plasma source 104 are perpendicular to each other along the perimeter of the processing area 146. By positioning the gas injector 192 and the liner assembly 156 at separate locations around the processing area, both components can be utilized independently within the first process system 100.

[0027]

[0035] The center of the liner assembly 156 of the remote plasma source 104 is positioned at a second angle θ2 with respect to the center of the opening 158 configured to feed the substrate 142 in and out of the processing area 146. The second angle θ2 is approximately 150 to 210 degrees, for example, approximately 175 to 195 degrees, for example, approximately 190 degrees. In some embodiments, the liner assembly 156 and the opening 158 are aligned along similar axes. By aligning the liner assembly 156 and the opening 158, the plasma can flow uniformly across the substrate 142 and be discharged through one or more exhaust passages 196a, 196b on either side of the opening 158. Positioning the gas injector 192 and the opening 158 at angles to each other enables a helical gas flow across the entire surface of the substrate 142. A helical gas flow has been shown to enable the formation of a more uniform oxide.

[0028]

[0036] The second process system 100a and the third process system 100b shown in Figures 2A and 2B can be used instead of the first process system 100 shown in Figures 1A and 1B. The second process system 100a and the third process system 100b are separate process systems, but can be used together to perform the processes described herein. Each of the second process system 100a and the third process system 100b is vacuum-coupled so that a substrate such as the substrate 142 passing between the second process system 100a and the third process system 100b is kept in a vacuum environment and not exposed to the atmosphere. Figure 2A is a schematic cross-sectional plan view of the second process system 100a. Figure 2B is a schematic cross-sectional plan view of the third process system 100b. The second process system 100a and the third process system 100b are similar to the first process system 100, except that the second process system 100a does not include a remote plasma source 104, and the third process system 100b does not include a gas injector 192.

[0029]

[0037] By separating the remote plasma source 104 and the gas injector 192 into two separate process systems 100a and 100b, the high-pressure oxidation process can be performed in a processing area 146 separate from the low-pressure plasma process. Separating process systems 100a and 100b improves process flexibility and the efficiency of maintenance performed on either process system 100a or 100b.

[0030]

[0038] As shown in Figure 2A, the second process system 100a includes a passage 157 on the opposite side of the opening 158. The passage 157 may be configured to include one or more sensors, an exhaust liner, or a process gas injector located therein. As shown in Figure 2B, the third process system 100b includes a passage 191 perpendicular to the opening 158 and the liner assembly 156. The passage 191 may be configured to include one or more sensors or an exhaust liner.

[0031]

[0039] Figure 3 is a schematic cross-sectional side view of the fourth process system 300. The fourth process system 300 includes a chamber body 302, a shower head 308 disposed within the chamber body 302, a substrate support 304, and an induction coil 306 disposed around the chamber body 302. The fourth process system 300 can be used in place of any one of the first process system 100, the second process system 100a, or the third process system 100b. The fourth process system 300 is configured to enable high-pressure oxidation and low-pressure plasma processes.

[0032]

[0040] The showerhead 308 is positioned above the substrate support 304 within the chamber body 302. The showerhead 308 is configured to distribute one or a combination of process gas and / or plasma into the processing area 315 of the fourth process system 300. The showerhead 308 includes a plurality of gas passages 312 formed through it. The plurality of gas passages 312 may be fluidly connected not only to the processing area 315 but also to a plenum 310 positioned above the showerhead 308. The gas source 316 is fluidly connected to the plenum 310 through a passage 314 formed within the chamber body 302. The gas source 316 is configured to supply one or more process gases, such as one or more oxidizers. One or more oxidizers may be hydrogen (H2), oxygen (O2), ozone (O3), nitrous oxide (N2O), water / water vapor (H2O), hydrogen peroxide (H2O2), or hydroxide (OH2O2). - The mixture contains one or a mixture of water (H2O), ozone (O3), and / or hydrogen peroxide (H2O2). A mixture of water (H2O), ozone (O3), and / or hydrogen peroxide (H2O2) may be delivered by the gas source 316 during high-pressure processes, for example, processes using pressures above about 50 Torr. A mixture of hydrogen (H2) and oxygen (O2) is introduced during low-pressure processes, such as processes with pressures from about 0.5 Torr to about 5 Torr. The mixture of hydrogen and oxygen during low-pressure processes contains oxygen radicals (O2). * ) Improves the lifespan of the species.

[0033]

[0041] One or more exhaust passages 318 are formed through the chamber body 302. The one or more exhaust passages 318 are formed below the substrate support 304 and the induction coil 306. The one or more exhaust passages 318 are coupled to an exhaust pump (not shown) and configured to remove gas and / or plasma from the processing area 315. The substrate support 304 is located within the processing area 315 and is configured to support a substrate such as a substrate 142. The substrate support 304 is configured to rotate around a central axis and act in one or more directions.

[0034]

[0042] The induction coil 306 is positioned around the chamber body 302. The induction coil 306 is configured to generate plasma within the processing area 315. The induction coil 306 is coupled to a power supply 320, which is a radio frequency (RF) power supply. The power supply 320 is configured to supply power to the induction coil 306 and generate plasma within the processing area 315 during the plasma process.

[0035]

[0043] Figure 4 is a schematic cross-sectional side view of the fifth process system 400. The fifth process system 400 is a batch process system that can process multiple substrates 142 simultaneously. The fifth process system 400 may be configured to perform a high-pressure oxidation step. The oxidizer is supplied to the processing area 415 of the fifth process system 400 from a plurality of gas inlets 406. The plurality of gas inlets 406 may be nozzles or injectors and are coupled to a gas distribution tower 404. The plurality of gas inlets 406 are arranged along the gas distribution tower 404 and are configured to supply process gas to various locations within the processing area 415. A gas supply unit 418 is fluidically coupled to the gas distribution tower 404 and the plurality of gas inlets 406. The gas supply unit 418 can supply hydrogen (H2), oxygen (O2), ozone (O3), nitrous oxide (N2O), water / water vapor (H2O), hydrogen peroxide (H2O2), or hydroxide (OH) -The system is configured to supply one or a mixture of the following: A mixture of water (H2O), ozone (O3), and / or hydrogen peroxide (H2O2) may be delivered by the gas supply unit 418 during the high-pressure process, for example, during the process using a pressure greater than about 50 Torr. A mixture of hydrogen (H2) and oxygen (O2) may then be introduced into the fifth process system 400 during the low-pressure process, such as the process at a pressure of less than about 1 Torr, in order to perform the batch low-pressure process. The mixture of hydrogen and oxygen burns during the low-pressure process to form atomic oxygen.

[0036]

[0044] Multiple substrates 142 are placed on a carrier assembly 408. The carrier assembly 408 includes multiple substrate support shelves 412. Each support shelf 412 has a substrate support surface. The substrate support surface may include a single support ring or may include multiple inconspicuous substrate support ledges. Each pair of support shelves 412 forms a slot between them for the insertion of substrates 142. Each support shelf 412 is associated with at least one gas inlet 406 such that at least one gas inlet 406 is located parallel to or above each support shelf 412. The support shelves 412 are parallel to each other and form a row of support shelves 412. Both the carrier assembly 408 and the gas distribution tower 404 are located within the processing area 415 of the chamber body 402.

[0037]

[0045] One or more exhaust passages 410 are formed through the chamber body 402. One or more exhaust passages 410 are formed below the substrate support shelf 412. One or more exhaust passages 410 are coupled to an exhaust pump (not shown) and configured to remove gas and / or plasma from the processing area 415.

[0038]

[0046] Figures 5A to 5C are schematic cross-sectional side views of the device stack 500 in the formation method 600. The device stack 500 includes multiple layers, such as multiple oxide layers 502 and multiple nitride layers 504. The oxide layers 502 are made of silicon oxide material. The nitride layers 504 are made of silicon nitride material. Each pair of oxide layers 502 is separated by a nitride layer 504, and the oxide layers 502 and nitride layers 504 are stacked alternately. Each of the oxide layers 502 and nitride layers 504 has a thickness of about 10 nm to about 30 nm, for example, about 15 nm to about 25 nm, for example, about 20 nm. A single oxide layer 502 and a single nitride layer 504 in contact with each other bond to form a pair 505. The presence of more than 100 pairs 505 of oxide layers 502 and nitride layers 504 means that there are at least 100 oxide layers 502 and at least 100 nitride layers 504. In some embodiments, the presence of more than 125 pairs of oxide layer 502 and nitride layer 504 in 505 means that there are at least 125 oxide layer 502 and at least 125 nitride layer 504. In some embodiments, the presence of more than 140 pairs of oxide layer 502 and nitride layer 504 in 505 means that there are at least 140 oxide layer 502 and at least 140 nitride layer 504.

[0039]

[0047] The device stack 500 includes a plurality of features 520 formed therein. The features 520 may be trenches or holes formed in the device stack 500. The features 520 are formed through a plurality of pairs 505, and the features 520 are formed through at least 100 pairs 505, for example, at least 125 pairs 505, for example, at least 140 pairs 505. The features 520 are formed from the top surface 518 of the device stack 500 to the bottom surface 509 of each feature 520. Each feature 520 is formed from two parts 510, 512. The two parts 510, 512 are a first part 510 and a second part 512. The first part 510 is located inward from the top surface 518, and the second part 512 is adjacent to the first part 510 and extends further inward from the bottom of the first part 510 away from the top surface 518. The first portion 510 includes at least pairs of 50 to 505, for example, at least pairs of 60 to 505, for example, at least pairs of 70 to 505. Similarly, the second portion 512 includes at least pairs of 50 to 505, for example, at least pairs of 60 to 505, for example, at least pairs of 70 to 505. The first portion 510 and the second portion 512 are separated by a transition portion 514.

[0040]

[0048] As the depth of each portion 510, 512 of the feature 520 within the device stack 500 increases, the width of the feature 520 decreases, making the feature 520 narrower. Thus, as the first portion 510 extends away from the top surface 518 toward the bottom surface 509, the feature 520 narrows. Similarly, as the second portion 512 extends away from the top surface 518 toward the bottom surface 509, the feature 520 narrows. In the transition section 514, the width of the feature 520 increases where the trench extends from the first portion 510 to the second portion 512. The feature 520 expands as a transition section 514 by using two separate processes to form the feature 520. The second portion 512 may be formed before the formation of the first portion 510. This causes the transition section 514 to include a change in width. The bottom surface 509 of each feature 520 may further include a base that is wider than the bottom of the second portion 512.

[0041]

[0049] The inner surface of each feature 520 is coated with a silicon layer 508 such that the silicon layer 508 is formed on the walls of each feature 520. The silicon layer 508 acts as a liner for each feature 520, covering both the first portion 510 and the second portion 512. The silicon layer 508 is deposited using an atomic layer deposition (ALD) process. The silicon layer 508 may be a silicon nitride layer, amorphous silicon, or polysilicon. In some embodiments, the silicon layer 508 is a silicon nitride layer.

[0042]

[0050] Each feature has an aspect ratio. The aspect ratio is the ratio of the depth of feature 520 to the width of feature 520, measured at the top opening that restricts the transport of reactants. The width of feature 520 is the width at the top opening of the first portion 510 or the top opening of the second portion 512, and the width of feature 520 is measured as the width adjacent to the top surface 518 of the device stack 500. The aspect ratio is greater than approximately 70:1, for example greater than approximately 75:1, for example greater than approximately 100:1, for example greater than approximately 120:1, for example greater than approximately 150:1, for example greater than approximately 170:1.

[0043]

[0051] Method 600 is performed on the device stack 500. Method 600, illustrated in Figure 6, includes step 602 of positioning the substrate in the first process chamber. The substrate includes the device stack 500 and may be a substrate similar to the substrate 142 in Figures 1A, 1B, 2, 3, and 4. The first process chamber may be any one of the first process system 100, the second process system 100a, the fourth process system 300, or the fifth process system 400. The substrate is placed on the substrate support surface within the first process chamber.

[0044]

[0052] Once the substrate is positioned in the first process chamber, the substrate is exposed to an oxidizing agent 516 at a first pressure during another step 604. The oxidizing agent 516 contains oxygen, hydrogen (H2), oxygen (O2), ozone (O3), nitrous oxide (N2O), water / water vapor (H2O), hydrogen peroxide (H2O2), or hydroxide (OH) - ) may be one of or a combination thereof. In one embodiment, the oxidizing agent 516 includes water vapor (H2O), ozone (O3), and / or hydrogen peroxide (H2O2). In another embodiment, the oxidizing agent 516 includes ozone (O3) and hydrogen (H2). The oxidizing agent 516 can be flowed together with the carrier gas to make the oxidizing agent 516 part of a mixed oxidizing agent comprising the oxidizing agent 516 and the carrier gas. The carrier gas may be one of or a combination thereof of helium (He), hydrogen (H2), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), or nitrogen (N2). Since the mixed oxidizing agent consists almost entirely of the oxidizing agent 516 and the carrier gas, the mixed oxidizing agent is entirely one or more oxidizing agents 516 and a carrier gas. Water vapor, ozone, or hydrogen peroxide can be used alone or in combination. The oxidizing agent 516 induces the formation of an oxide layer 522 on the silicon layer 508, as shown in Figure 5B. When water vapor, ozone, and hydrogen peroxide are used individually, the growth rate of the oxide layer 522 is slower compared to when at least two of the water vapor, ozone / hydrogen, and hydrogen peroxide are used in combination.

[0045]

[0053] The first pressure is greater than about 10 Torr, for example, greater than about 15 Torr, for example, greater than about 20 Torr, for example, greater than about 50 Torr, for example, between about 50 Torr and about 760 Torr. The partial pressure of the oxidizing agent is greater than the partial pressure of about 10 Torr. In some embodiments, the partial pressure of the oxidizing agent is about 50 Torr or more, preferably 100 Torr or more.

[0046]

[0054] The temperature of the substrate and the processing area in which the substrate is placed during process 604 is approximately 500°C to approximately 1500°C, for example, approximately 600°C to approximately 1200°C, for example, approximately 700°C to approximately 1000°C, for example, approximately 900°C.

[0047]

[0055] As shown in Figure 7, the growth rate of silicon dioxide generally increases with increasing pressure, peaking when the partial pressure of ozone in the mixed process gas of O3 and H2O is approximately 20% to 80%, for example, approximately 30% to 70%. The graph includes three datasets. The first dataset is the growth rate at a first pressure P1. The second dataset is the growth rate at a second pressure P2. The third dataset is the growth rate at a third pressure P3. Each dataset includes data points in which the mixed process gas contains ozone (O3) at different partial pressure percentages relative to the overall pressure of the mixture. The mixture in Figure 7 contains ozone (O3) and water vapor (H2O). The first pressure P1 is approximately 10 Torr to 12 Torr. The second pressure P2 is approximately 20 Torr. The third pressure P3 is approximately 60 Torr. This data confirms that in the high-pressure region exceeding 10 Torr, H2O and O3 react to form more reactive species than predicted from the mixture of non-reactive components.

[0048]

[0056] The transition zone 514 can function as a choke point during oxide formation. Increasing the pressure and partial pressure during the substrate's exposure to the oxidizer 516 helps to deliver the oxidizer 516 to the lower portion of feature 520, such as the second portion 512 of feature 520. Increasing the pressure also helps to reduce the effect of the adhesion coefficient on oxidation within feature 520 and complements the high flow rate of the oxidizer to high aspect ratio features caused by the increased surface area. Thus, high oxidizer partial pressure has been shown to improve the fit of the oxide layer within high aspect ratio features.

[0049]

[0057] As shown in Figure 5B, the oxide layer 522 is grown to a desired thickness before exposure to the oxidizing agent is stopped during another step 606. When the substrate's exposure to the oxidizing agent is stopped, the growth of the oxide layer 522 on the silicon layer 508 stops. The desired thickness of the oxide layer 522 is a first thickness T1. The first thickness T1 is approximately 1 nm to approximately 3 nm. Therefore, the first thickness T1 is approximately 1 nm to approximately 1.5 nm, approximately 1.5 nm to approximately 2 nm, or approximately 2 nm to approximately 3 nm. The first thickness T1 is large enough to improve the uniformity of oxide growth within the feature 520 during a later process step, but small enough to improve the manufacturing speed of the device stack 500.

[0050]

[0058] The oxide layer 522 formed during step 604 has been found to be very uniform throughout the feature 520. Previous attempts to oxidize the inner surface of feature 520 have been limited to features 520 having smaller depths D. The depths D of the feature 520 described herein are greater than about 5 μm, for example greater than about 7 μm, for example greater than about 8 μm, for example greater than about 10 μm. The method 600 described herein makes it possible to form a uniform oxide layer 522 within features such as feature 520 having a large depth D, for example greater than 5 μm.

[0051]

[0059] If the substrate's exposure to the oxidizing agent is stopped during step 606, the substrate may optionally be moved to a second process chamber during another step 608. The movement of the substrate to the second process chamber involves a decrease in the pressure around the substrate. The pressure decreases from the first pressure to the second pressure. The second pressure is less than about 10 Torr, e.g., less than about 7 Torr, e.g., less than about 5 Torr, e.g., between about 0.1 Torr and about 5 Torr. The pressure decreases in either the first or second process chamber.

[0052]

[0060] In some embodiments, the pressure in the processing area of ​​the first process chamber is reduced before the substrate is moved to the second process chamber, bringing the processing area of ​​the second process chamber to a second pressure. In other embodiments, the pressure in the processing area of ​​the first process chamber remains constant while the substrate is moved to the second process chamber, and once the substrate enters the second process chamber, the pressure in the processing area of ​​the second process chamber is reduced to a second pressure. In yet another embodiment, the substrate remains in the first process chamber, and the pressure in the processing area of ​​the first process chamber is reduced from a first pressure to a second pressure. There may be an intermediate chamber, such as a transfer chamber (not shown), connecting the first and second process chambers. This allows the substrate to pass through the transfer chamber at an intermediate pressure between the first and second pressures while being transferred from the first process chamber to the second process chamber. In some embodiments, it is generally explained that the pressure around the substrate decreases from a first pressure to a second pressure.

[0053]

[0061] The second process chamber may be any one of the first process system 100, the third process system 100b, or the fourth process system 300. The second process chamber is equipped to perform plasma processing on a substrate.

[0054]

[0062] Once the substrate is positioned in the second process chamber, it is exposed to an oxygen-containing plasma at a second pressure during another step 610. The oxygen-containing plasma is configured to perform radical oxidation of the substrate features 520. The oxygen-containing plasma is formed using a remote plasma source (RPS), an inductively coupled plasma (ICP) source, a capacitively coupled plasma (CCP) source, or thermal radical combustion.

[0055]

[0063] Oxygen-containing plasmas contain radicalized oxygen atoms. The oxygen-containing plasmas described herein contain both hydrogen molecules and oxygen molecules. Oxygen-containing plasmas include hydrogen (H2), oxygen (O2), nitrous oxide (N2O), ozone (O3), water / water vapor (H2O), hydrogen peroxide (H2O2), or hydroxide (OH- The oxygen-containing plasma may further include one or more additional oxygen-containing molecules, such as one or a combination thereof. In one embodiment, the oxygen-containing plasma includes water vapor (H2O), ozone (O3), and / or hydrogen peroxide (H2O2). In another embodiment, the oxygen-containing plasma includes ozone (O3) and hydrogen (H2). The oxygen-containing plasma can be flowed together with a carrier gas to become part of a mixed oxygen plasma containing the oxygen-containing plasma and the carrier gas. The carrier gas may be one or a combination thereof of helium (He), hydrogen (H2), neon (Ne), argon (Ar), krypton (Kr), or xenon (Xe). The mixed oxygen plasma consists almost entirely of the oxygen-containing plasma and the carrier gas, and the mixed oxygen plasma is an oxygen and hydrogen plasma flowed together with the carrier gas.

[0056]

[0064] While step 610 is performed and the substrate is exposed to the oxygen-containing plasma, the processing area is maintained at a second pressure of less than about 10 Torr, e.g., less than about 7 Torr, e.g., less than about 5 Torr, e.g.

[0057]

[0065] The temperature of the substrate and the processing area in which the substrate is placed during process 610 is approximately 500°C to approximately 1500°C, for example, approximately 600°C to approximately 1200°C, for example, approximately 700°C to approximately 1000°C, for example, approximately 900°C.

[0058]

[0066] During step 610, the oxide layer 522 grows to a desired thickness before exposure to the oxygen-containing plasma is stopped. When exposure of the substrate to the oxygen-containing plasma is stopped, the growth of the oxide layer 522 on the silicon layer 508 stops. The desired thickness of the oxide layer 522 after step 610 is a second thickness T2. The second thickness T2 is approximately 2 nm to approximately 10 nm, for example, approximately 2 nm to approximately 8 nm, for example, approximately 3 nm to approximately 6 nm, for example, approximately 4 nm to approximately 5 nm. In some embodiments, the second thickness T2 is approximately 6 nm to approximately 10 nm.

[0059]

[0067] The growth rate of the oxide layer 522 during oxygen-containing plasma exposure in step 610 is higher than the growth rate of the oxide layer 522 during high-pressure oxide exposure in step 604. Plasma exposure in step 610 is used to increase the overall growth rate of the oxide layer 522. The growth rate of the oxide layer 522 during high-pressure oxide exposure in step 604 is a first growth rate, less than approximately 30 angstroms / (square root), e.g., less than approximately 25 angstroms / (square root), e.g., less than approximately 20 angstroms / (square root). The growth rate of the oxide layer 522 during oxygen-containing plasma exposure in step 610 is greater than approximately 20 angstroms / (square root), e.g., between approximately 30 angstroms / (square root) and approximately 40 angstroms / (square root).

[0060]

[0068] As described herein, the high-pressure oxide exposure in step 604 and the oxygen-containing plasma exposure in step 610 can each be performed in either the same process chamber or different process chambers. In one embodiment, both the high-pressure oxide exposure in step 604 and the oxygen-containing plasma exposure in step 610 are performed in the first process system 100. In another embodiment, the high-pressure oxide exposure in step 604 is performed in the second process system 100a, and the oxygen-containing plasma exposure in step 610 is performed in the third process system 100b. In yet another embodiment, both the high-pressure oxide exposure in step 604 and the oxygen-containing plasma exposure in step 610 are performed in the fourth process system 300. In yet another embodiment, the high-pressure oxide exposure in step 604 is performed in a process system similar to the fourth process system 300, and the oxygen-containing plasma exposure in step 610 is performed in a different process system similar to the fourth process system 300. In yet another embodiment, the high-pressure oxide exposure in step 604 is performed in a fifth process system 400, and the oxygen-containing plasma exposure in step 610 is performed in either a third process system 100b or a fourth process system 300.

[0061]

[0069] In yet another embodiment, the high-pressure process is performed in a furnace such as a fifth process system 400, and the oxygen-containing plasma exposure in process 610 is replaced by a low-pressure hydrogen (H2) and oxygen (O2) combustion process. The high-pressure process is performed at a pressure exceeding approximately 50 Torr. A mixture of hydrogen (H2) and oxygen (O2) can then be introduced into the fifth process system 400 during a low-pressure process, such as a process at a pressure of less than approximately 1 Torr. The low-pressure process is a batch low-pressure process. During the batch low-pressure process, the mixture of hydrogen and oxygen burns during the low-pressure process to form atomic oxygen. Combustion of the hydrogen and oxygen mixture is used instead of plasma exposure during batch processes such as the fifth process system 400.

[0062]

[0070] The process described herein ensures that the oxide layer 522 has a uniform thickness throughout the entire depth of the feature 520. The uniformity of the oxide layer 522 is measured by measuring the thickness of the oxide layer 522 in sections 530, 532 through the first portion 510 and the second portion 512 of the feature 520. The first section 530 is measured from the top surface 518 of the device stack 500 at approximately 250 nm to approximately 750 nm, e.g., approximately 300 nm to approximately 700 nm, e.g., approximately 400 nm to approximately 600 nm, e.g. The thickness of the oxide layer 522 measured in the first cross section 530 and the second cross section 532 exhibits high conformability. As described herein, conformability is measured as the thickness of the oxide layer 522 in the second cross section 532 relative to the thickness of the oxide layer 522 in the first cross section 530. Conformability using the method described herein has been found to be higher than about 95%, for example, higher than about 96%, for example, higher than about 97%, for example, higher than about 98%.

[0063]

[0071] While the foregoing applies to embodiments of the present disclosure, it is possible to devise other further embodiments of the present disclosure without departing from its basic scope as defined by the following claims.

Claims

1. Apparatus for processing substrates, suitable for use in semiconductor manufacturing, It is a process system, Chamber body and A process gas source is coupled to the chamber body and configured to introduce process gas into the processing area. Process systems including, A substrate support configured to support the substrate within the processing region, It is a controller, At a first pressure exceeding approximately 20 Torr, the substrate is exposed to the oxidizer from the process gas source. The pressure around the substrate is reduced from the first pressure to a second pressure of less than approximately 10 Torr. While the pressure around the substrate is the second pressure, the substrate is exposed to an oxygen-containing plasma. A controller configured as follows A device equipped with the following features.

2. The apparatus according to claim 1, wherein the process system further includes a plasma source coupled to the chamber body and configured to introduce plasma into the processing area.

3. The apparatus according to claim 1, wherein the process system is a first process system, and the apparatus further comprises a second process system including a plasma source coupled to a second chamber body and configured to introduce plasma into a second processing area.

4. The apparatus according to claim 1, wherein the process system is configured to process multiple substrates simultaneously.

5. The apparatus according to claim 4, wherein the substrate support further includes a plurality of substrate support shelves.

6. The apparatus according to claim 1, wherein the induction coil is arranged around the chamber body.

7. A non-transient computer-readable medium storing instructions suitable for use in semiconductor manufacturing, wherein, when the instructions are executed by a processor, the computer system... At a first pressure exceeding approximately 20 Torr, the substrate is exposed to the oxidizing agent. The pressure around the substrate is reduced from the first pressure to a second pressure of less than approximately 10 Torr. While the pressure around the substrate is the second pressure, the substrate is exposed to an oxygen-containing plasma. A non-transient, computer-readable medium that executes steps.

8. The medium according to claim 7, wherein the oxygen-containing plasma is formed using a remote plasma source or an inductively coupled plasma source.

9. The medium according to claim 7, wherein the oxidizing agent comprises one of ozone, nitrous oxide, water, hydrogen, and hydrogen peroxide, or a mixture thereof, and the oxygen-containing plasma comprises radicalized oxygen atoms.

10. The medium according to claim 7, wherein the first pressure is greater than approximately 50 Torr, the second pressure is less than approximately 5 Torr, and during the exposure of the substrate to the oxidizing agent and the exposure of the substrate to the oxygen-containing plasma, the substrate is placed on a substrate support at a temperature of approximately 600°C to approximately 1200°C, respectively.

11. A method for processing substrates suitable for use in semiconductor manufacturing, In order to form an oxide layer on the silicon wall or nitride wall on the substrate, a plurality of features having the silicon wall or nitride wall are exposed to an oxidizing agent at a first pressure exceeding approximately 50 Torr, The pressure around the substrate is reduced from the first pressure to a second pressure of less than approximately 5 Torr, In order to increase the thickness of the oxide layer, the substrate is exposed to an oxygen-containing plasma while the pressure around the substrate is the second pressure. A method that includes this.

12. The method according to claim 11, wherein the oxide layer has a first thickness of about 2 nm to about 3 nm after the plurality of features are exposed to the oxidizing agent, and a second thickness of about 6 nm to about 10 nm after the plurality of features are exposed to the oxygen-containing plasma.

13. The method according to claim 11, wherein exposure of the plurality of features to the oxidizing agent is performed in a first chamber, and exposure of the plurality of features to the oxygen-containing plasma is performed in a second chamber.

14. The method according to claim 11, wherein the plurality of features have nitride walls, the nitride walls are silicon nitride surfaces, and the oxide layer is silicon oxide.

15. The method according to claim 11, wherein each of the plurality of features has a depth greater than about 5 μm and an aspect ratio greater than about 70:

1.

16. The method according to claim 11, wherein during the exposure of the substrate to the oxidizing agent and during the exposure of the substrate to the oxygen-containing plasma, the substrate is placed on a substrate support at a temperature of approximately 600°C to approximately 1200°C, respectively.

17. The method according to claim 11, wherein the feature is formed in a laminate comprising a plurality of silicon oxide layers and a plurality of silicon nitride layers.

18. The method according to claim 11, wherein the oxidizing agent comprises one of ozone, nitrous oxide, water, hydrogen, and hydrogen peroxide, or a mixture thereof.

19. The method according to claim 11, wherein the oxygen-containing plasma includes radicalized oxygen atoms.

20. The method according to claim 19, wherein the oxygen-containing plasma further comprises hydrogen and oxygen molecules.

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