Processing chamber with boost and pulsing capabilities

Abstract

A process chamber is described that includes at least one gas reservoir connected to and in fluid communication with a cover by a quick switching valve and a gas reservoir line. Processing methods, such as etching methods, using the processing chamber are also described.

Description

BACKGROUND OF THE INVENTION

[0001] Reliably producing sub-micron and smaller features is one of the key requirements for very large scale integration (VLSI) and ultra large scale integration (ULSI) of semiconductor components. However, with the continued miniaturization of circuit technology, the size and pitch of circuit features such as interconnects pose additional requirements on processing capabilities. Precise placement of high aspect ratio features is required for various semiconductor components (e.g., interconnects, vias, capacitors, transistors). Reliable formation of these components is crucial for further increasing component density.

[0002] In addition, the electronics component industry and the semiconductor industry continue to strive to improve production yields while improving the uniformity of layers deposited on substrates with increasingly large surface areas. The combination of these same factors with new materials also provides a higher degree of circuit integration per unit area on the substrate. As the development progresses towards smaller component features, the need for better process control of layer properties increases.

[0003] During semiconductor manufacturing, it is often advantageous to selectively etch material from one surface compared to a separate surface. For example, etching a specific film from a dielectric surface without removing the film from an adjacent metal (or other dielectric) surface.

[0004] In many cases, etching a film requires exposing the substrate to one or more etching gases for a short period of time. The amount of time the substrate is exposed to the etchant affects the selectivity of the etching process. Generally, an increase in the time of exposure to the etching gas results in a decrease in etching selectivity. Existing processing chambers cannot pulse (feed and purge the processing region) the etchant fast enough to maintain a high selectivity between oxide and nitride surfaces.

[0005] Accordingly, there is a need in the art for devices and methods for improving etching selectivity. SUMMARY OF THE INVENTION

[0006] One or more embodiments of the present disclosure are directed to a processing chamber including a chamber body having sidewalls and a bottom. A lid covers the chamber body, enclosing a processing space. At least one gas reservoir is connected to and in fluid communication with the lid through a fast-switching valve and a reservoir line.

[0007] Additional embodiments of the present disclosure are directed to methods of selectively etching a substrate. These methods include exposing a substrate in a processing space of a processing chamber to at least one etching gas stream from at least one reservoir in a processing chamber lid for an etching time period. The substrate has a first material and a second material. The at least one reservoir is connected to the processing chamber lid by a fast-switching valve. The at least one etching gas selectively etches a third material from the first material relative to the second material. The etching gas in the processing space is purged.

[0008] Additional embodiments of the present disclosure are directed to a processing chamber including a chamber body having sidewalls and a bottom. A lid covers the chamber body and encloses the processing space. A processing gas inlet in one or more of the chamber body or the lid is configured to provide a flow of processing gas into the processing space. A first reservoir is connected to the lid by a fast-switching valve and a first reservoir line and is in fluid communication with the lid. The first reservoir has a first etching gas that includes a predetermined mixture of an etchant and a carrier gas. A second reservoir is connected to the lid by a fast-switching valve and a second reservoir line and is in fluid communication with the lid. The second reservoir has a second etching gas that includes a predetermined mixture of an etchant and a carrier gas. Each of the first reservoir and the second reservoir has a volume sufficient to maintain a constant high-level etchant flow to the processing space during a pulse of less than or equal to 3 seconds in duration. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] To facilitate a detailed understanding of the above-described features of the present disclosure, the present disclosure briefly summarized above may be described in more detail with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only typical embodiments of the present disclosure and should not be considered limiting of its scope, as the present disclosure may admit to other equivalent embodiments.

[0010] Figure 1 A processing chamber having reservoirs and gas boxes is shown in accordance with one or more embodiments of the present disclosure;

[0011] Figure 2 A cross-sectional schematic view of a processing chamber having reservoirs and gas boxes is shown in accordance with one or more embodiments of the present disclosure;

[0012] Figure 3 A graph showing the amount of etching of different materials over time, illustrating a latent delay; and

[0013] Figure 4 A schematic view of a gas flow is shown in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0014] Before describing several exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of the structures or process steps set forth in the following description. The present disclosure can have other embodiments and can be practiced or carried out in various ways.

[0015] As used in this specification and the appended claims, the term "substrate" refers to a surface or a portion of a surface on which a process acts. Those skilled in the art will also understand that reference to a substrate may also refer only to a portion of the substrate, unless the context clearly indicates otherwise. Additionally, referring to depositing on a substrate may refer to a bare substrate and a substrate on which one or more films or features are deposited or formed.

[0016] As used herein, "substrate" refers to any substrate or the surface of a material formed on a substrate, on which film processing is performed during manufacturing. For example, depending on the application, the substrate surface on which processing can be performed includes materials such as silicon, silicon oxide, strained silicon, silicon on insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other materials such as metals, metal nitrides, metal alloys, and other conductive materials. Substrates include, but are not limited to, semiconductor wafers. The substrate can be exposed to a pre-treatment process to polish, etch, reduce, oxidize, hydroxylate, anneal, UV-cure, electron-beam cure, and / or bake the substrate surface. In addition to performing film processing directly on the surface of the substrate itself, in the present disclosure, any disclosed film processing step can also be performed on an underlying layer formed on the substrate, as disclosed in more detail below, and the term "substrate surface" is intended to include such an underlying layer as referred to in the context. Thus, for example, in the case where a film / layer or a portion of a film / layer has been deposited on the substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0017] The terms "substrate support" and "substrate support base" used in this specification and the appended claims can be used interchangeably.

[0018] Related terms such as "above" and "below" used in this specification and the appended claims should not be considered as limiting the scope of the present disclosure to a spatial physical orientation. Thus, the use of relative terms should not be restricted to the directions specified by gravity.

[0019] Existing processing chamber hardware is capable of performing a directional etching process using radio frequency pulses or conventional etching reactions. However, existing hardware cannot perform an "etchant pulse" process to achieve high SiO / SiN etching selectivity. As used in this specification and the appended claims, unless otherwise specified, the use of a general chemical formula such as SiO refers to a material having any suitable ratio of silicon and oxygen atoms. For example, a SiN film may contain Si 3 N 4or approximately three silicon atoms for every four nitrogen atoms. Those skilled in the art will recognize that the atomic composition of the film may not strictly conform to the target stoichiometry. Accordingly, the use of general formulas (e.g., SiO or SiN) is for identification purposes only.

[0020] Some embodiments of the present disclosure provide a processing chamber having deposition and etching capabilities. In some embodiments, an etch CVD combination chamber is described that has an improved etch chamber body with a smaller cavity. In some embodiments, the combination chamber includes heating capabilities. In some embodiments, the combination chamber is configured to process special etchants that may be hazardous when used with existing chamber hardware.

[0021] RF pulses and directional etching do not achieve the desired selectivity and may damage the SiN spacer in some applications, resulting in leakage current. Some embodiments of the present disclosure provide etchant pulse capabilities to improve the SiO / SiN selectivity. Some embodiments advantageously provide the ability to achieve high SiO / SiN selectivity. In some embodiments, the SiN spacer can be retained while etching SiO. In some embodiments, the improved selectivity of the etching process reduces failures due to leakage current caused by SiN loss.

[0022] Some embodiments of the present disclosure provide a processing chamber having one or more etchant reservoirs and fast-switching valves. In some embodiments, the etchant can be pressurized to a high pressure in the reservoir, allowing for rapid filling of the processing cavity to initiate the etching process. After a precisely controlled reaction time, the etchant can be rapidly pumped out of the processing cavity. With the rapid operation of the fast-switching valve, the reaction time can be very short. This is referred to as an "etchant pulse."

[0023] Some embodiments of the present disclosure provide an improved etch chamber body having a smaller cavity, heating capabilities, and a bipolar electrostatic chuck. Each of the above can be used to implement special etchants and a wide pressure range (from a few torr to a few millitorr).

[0024] Some embodiments of the present disclosure provide a new gas delivery system having individual gas injection (IGI) capabilities, reservoirs, and fast-switching valves. The special etchant is IGI, meaning it has an independent gas line from the other gases to the chamber lid. The IGI gas line and lid can be heated. In some embodiments, the separation and heating avoid condensation caused by the mixing of special etchants with each other or with other gases. The reservoirs and fast-switching valves can be integrated into the etch gas line.

[0025] In some embodiments, the process chamber lid and the gas distribution plate / showerhead are based on modified CVD-type hardware with heating capabilities. This advantageously helps to mix and distribute the etchant with good uniformity.

[0026] The processes of some embodiments use a high SiO / SiN etch selectivity with efficient isotropic cleaning capabilities.

[0027] The high-selectivity process mechanism according to some embodiments uses a latent delay, where only SiO is etched in the first few seconds of the reaction. The etchant pulse of some embodiments is controlled such that the etching reaction remains within the latent delay region. The proximity of the etch gas reservoir to the processing region allows the etching reaction to remain within the latent delay time range. When using a conventional process chamber gas box or in-chamber gas line, the time to replace the gas in the processing region is too long, such that the reaction cannot remain within the latent delay period and there is no selective etching of SiO relative to SiN.

[0028] Reference Figure 1 and Figure 2 With reference to

[0029] One or more embodiments of the present disclosure are directed to a process chamber 100. The process chamber 100 has a chamber body 110, the chamber body 110 having at least one sidewall 112 and a bottom 114, the sidewall and the bottom enclosing an internal volume 116.

[0030] A substrate support 130 is located within the internal volume 116. The substrate support 130 has a support surface 132, which is configured to support a wafer 135 (also referred to as a substrate) during processing. The substrate support 130 of some embodiments is positioned on a support shaft 134 located within the internal volume 116. The support shaft 134 of some embodiments is configured to move the substrate support 130 closer to and farther from the lid 120 of the process chamber 100.

[0031] The lid 120 is located on the chamber body 110 and encloses a processing space 125. The lid 120 of some embodiments can be heated to at least 100 °C or higher. The processing space 125 is part of the internal volume 116 of the process chamber 100 and is located between the support surface 132 of the substrate support 130 and the lid 120. The processing space 125 of some embodiments can be minimized in volume to increase the replacement rate of the gas within the processing space 125. The smaller processing space 125 allows for a rapid switch between different potentially incompatible process gases.

[0032] In some embodiments, the processing chamber 100 includes a process gas inlet 160 in a sidewall 112 of the chamber body 110. The process gas inlet 160 is configured to provide a flow of process gas into the processing space 125. In some embodiments, the process gas inlet 160 is located in one or more of the chamber body 110 or the lid 120. In some embodiments, the process gas inlet 160 is configured to provide a flow of process gas parallel to the surface 137 of the wafer 135. In some embodiments, the process gas inlet 160 is configured to provide a flow of process gas perpendicular to the surface 137 of the wafer 135. In some embodiments, there is a process gas inlet 160 in the sidewall 112 of the chamber body 110 and a process gas inlet 160 in the lid 120.

[0033] The process gas inlet 160 of some embodiments is located in the sidewall 112 of the chamber body 110 and allows process gas to flow into the processing space 125 from the sidewall. To prevent or minimize the inflow of process gas into the internal volume 116 of the processing chamber 100, in some embodiments, an edge ring 170 is located around the substrate support 130.

[0034] The processing chamber 100 includes at least one exhaust port 171, which can be connected to a vacuum source 172. Suitable vacuum sources 172 include, but are not limited to, an in-house vacuum line or a stand-alone vacuum pump. In some embodiments, as Figure 2 shown, at least one exhaust port 171 is located at the bottom 114 of the chamber body 110. In some embodiments, at least one exhaust port 171 is located in the sidewall 112 of the chamber body 110 on the side of the processing chamber 100 opposite the process gas inlet 160.

[0035] One or more embodiments of the present disclosure include at least one reservoir connected to the lid 120. The at least one reservoir is connected to and in fluid communication with the lid 120 through a quick-switch valve 210 and a reservoir line. In some embodiments, as shown in the illustrated embodiment, there are two reservoirs, a first reservoir 200a and a second reservoir 200b. The first reservoir 200a is connected to and in fluid communication with the lid 120 through a first reservoir line 220a and a quick-switch valve 210. The second reservoir 200b is connected to and in fluid communication with the lid 120 through a second reservoir line 220b and a quick-switch valve 210. As used in this specification and the appended claims, a quick-switch valve is a valve having the ability to open / close quickly. The response time of a quick-switch valve is typically less than or equal to 50 milliseconds.

[0036] The volume of at least one gas reservoir can be any suitable volume. To reduce response time, it may be advantageous to have a reservoir close to the lid 120 and the fast-switching valve 210, which results in hardware limitations on the reservoir. Within the hardware limitations, a larger volume reservoir is generally better for a stable gas flow. In some embodiments, at least one gas reservoir has a volume greater than or equal to 100 cc, 200 cc, 300 cc, 400 cc, 500 cc, 600 cc, 700 cc, 800 cc, 900 cc, or 1000 cc.

[0037] The length of the reservoir line connecting the gas reservoir to the fast-switching valve 210 is minimized to ensure a rapid change in the gas composition in the processing space 125. In some embodiments, the length of each reservoir line is less than or equal to 20 millimeters.

[0038] According to some embodiments, the volume of at least one gas reservoir is sufficient to maintain a constant high-level etchant flow to the processing space 125 throughout a pulse of less than or equal to 3 seconds.

[0039] The gas reservoirs of some embodiments are used to allow a rapid change of the processing gas within the processing space 125 to allow a selective etching process to maintain selectivity. In some embodiments, each gas reservoir contains a specific type of etchant. In some embodiments, each gas reservoir contains a predetermined mixture of reactant and carrier gas. The carrier gas acts as a diluent to form a predetermined concentration of etchant such that the gas can flow from the gas reservoir to the processing space 125 without the need for a separate push gas (carrier gas).

[0040] In some embodiments, the processing chamber 100 includes a gas box 180. The gas box 180 of some embodiments is configured to provide a flow of processing gas to the processing space 125 that is separate from the reservoir line. In some embodiments, the gas box 180 is configured to provide a flow of processing gas to the processing space 125 through a processing gas inlet 160 in the sidewall 112 of the chamber body 110, and the flow of processing gas has a different composition from the gas in any of the at least one gas reservoir.

[0041] The processing chamber 100 of some embodiments further includes a controller 190. The controller 190 is coupled to the processing chamber 100 through any suitable communication connection known to those skilled in the art. The controller 190 can control the operation of the processing chamber 100 through control valves, flow regulators, temperature controllers, etc., which is a conventional part of a semiconductor manufacturing processing chamber.

[0042] The controller 190 generally includes a central processing unit (CPU) 192, a memory 194, and support circuitry 196. The CPU 192 can be one of any form of general-purpose processor that can be used in an industrial environment. The memory 194 or non-transitory computer-readable medium can be accessed by the CPU 192 and can be one or more of memories such as random-access memory (RAM), read only memory (ROM), floppy disks, hard disks, or any other form of local or remote digital memory. The support circuitry 196 is coupled to the CPU 192 and can include a cache, a clock circuit, an input / output subsystem, a power supply, and the like. The various methods disclosed herein can generally be implemented under the control of the CPU 192 by the CPU 192 executing computer scripts stored, for example, as software routines in the memory 194 (or the memory of a particular processing chamber). When the computer scripts are executed by the CPU 192, the CPU 192 controls the processing chamber to perform processes according to the various methods.

[0043] In some embodiments, the controller 190 has at least one configuration selected from configurations of controlling a gas flow from a first gas reservoir 200a, a gas flow from a second gas reservoir 200b, a gas flow through a process gas inlet 160, or a fast-switching valve 210.

[0044] Figure 3 A graph showing the amount of film etched away from the surface over time on silicon oxide and silicon nitride surfaces is shown. As shown in the figure, the etching of the silicon oxide film begins shortly after exposure to the etching environment, and after some time, the silicon nitride film begins to etch. This period of time is referred to as the latent delay, also known as the latent delay period 300. The length of the latent delay depends on, for example, the etching temperature, the etchant concentration, and the film composition (such as density). According to some embodiments, the processing chamber 100 is configured to pulse an etching gas into the processing space 125 for a duration less than the latent delay. The pulsing of the etching gas includes filling the processing space 125 with an etchant chemical and purging the processing space 125 to remove the etchant chemical. The etching gas can be pulsed into the processing space 125 multiple times to remove a predetermined amount of the silicon oxide film while substantially not changing the thickness of the silicon nitride film. The term "substantially change the thickness" as used in this manner means that the thickness of the film increases or decreases by no more than 10%, 5%, 2%, or 1% relative to the initial thickness.

[0045] Figure 4Shows a schematic diagram of flow control of a processing chamber and related equipment in accordance with one or more embodiments of the present disclosure. Gas box 180 has one or more processing gases, which may include precursor ampoules or other gas sources. Gas flows from gas box 180 through a flow rate controller 182, which may be inside or outside gas box 180. As will be understood by those skilled in the art, the valve cluster 184 downstream of flow rate controller 182 includes a shut-off valve 184a, an inert gas purge valve 184b, and a bleed valve 184c.

[0046] A first reservoir 200a is illustrated as being connected to a first upstream gas source 201a through an upstream shut-off valve 202a, which can be used to refill the first reservoir 200a. This allows the first reservoir 200a to be closer to the processing space 125 than the gas box 180, allowing the processing space 125 to be filled with the first gas more quickly.

[0047] A second reservoir 200b is illustrated as being connected to a second upstream gas source 201b through an upstream shut-off valve 202b, which can be used to refill the second reservoir 200b. This allows the second reservoir 200b to be closer to the processing space 125 than the gas box 180, allowing the processing space 125 to be filled with the second gas more quickly.

[0048] The etch cycles of some embodiments are short enough to remain within the latency period 300. An etch cycle is defined as the amount of time, the reservoir pressure increase, or the total gas flow, starting from when the processing space 125 is filled with the reactive gas and ending when substantially all of the reactive gas has been purged from the processing space 125. When used in this manner, "substantially all of the reactive gas has been purged" means that less than 1%, 0.5%, or 0.1% of the reactive gas remains in the processing space 125 relative to the peak concentration of the reactive gas during the etch cycle. The total etch time is the sum of the amount of time for each etch cycle. For example, the total etch time for ten one-second etch cycles is ten seconds. In some embodiments, the etch time for any given etch cycle is less than or equal to 3 seconds, 2 seconds, or 1 second.

[0049] At least one reservoir is located within a minimum distance from the processing space to ensure that the etch cycle is less than 3 seconds. In some embodiments, each of the first reservoir 200a and the second reservoir 200b is located within a minimum distance from the processing space to ensure that the etch cycle is less than 3 seconds.

[0050] In some embodiments, the processing method further includes providing a flow of the processing gas from the gas box 180 connected to the processing chamber 100 into the processing space 125 of the processing chamber 100. The gas box 180 is configured to provide a flow of the processing gas to the processing space 125 separate from each of the reservoir pipelines.

[0051] In some embodiments, the etch chamber body includes an etch-resistant chamber body having a special coating. In some embodiments, the special coating is configured to resist corrosion from halogen-based substances such as fluorine or chlorine. In some embodiments, the modified chamber has a reduced volume in the chamber reaction cavity. In some embodiments, the volume in the chamber reaction cavity is less than or equal to 40 L, 35 L, 30 L, or 25 L. In some embodiments, the bipolar electrostatic chuck (ESC) handles a wider pressure range. In some embodiments, the bipolar ESC is configured to operate at pressures in the range of 0.1 microtorr to 1000 torr.

[0052] As used herein, the terms "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment" refer to a particular feature, structure, material, or characteristic described in connection with the embodiment being included in at least one embodiment of the present disclosure. Thus, appearances of phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the present disclosure. Moreover, in one or more embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner.

[0053] Although the present disclosure has been described with reference to particular embodiments, those skilled in the art will understand that the embodiments are only for illustrative purposes of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the methods and apparatuses of the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure may include modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A processing chamber, the processing chamber comprising: a chamber body having side walls and a bottom; a cover on the chamber body, the cover enclosing a processing space; and at least one gas reservoir connected to and in fluid communication with the cover via a quick-switch valve and a gas reservoir pipeline.

2. The processing chamber according to claim 1, wherein there are two reservoirs.

3. The processing chamber according to claim 2, wherein the two reservoirs contain different etchants.

4. The processing chamber according to claim 3, wherein each of the reservoirs comprises a predetermined mixture of reactants and carrier gas.

5. The processing chamber according to claim 1, wherein the at least one gas reservoir has a volume greater than or equal to 100 cc.

6. The processing chamber according to claim 1, wherein the at least one gas reservoir has a volume sufficient to maintain a constant high-level etchant flow to the processing space throughout a pulse of less than or equal to 3 seconds.

7. The processing chamber according to claim 1, wherein each gas reservoir pipeline has a length of less than or equal to 20 cm.

8. The processing chamber according to claim 1, further comprising a gas box connected to the processing chamber, the gas box being configured to provide a flow of processing gas to the processing space separate from each of the gas reservoir pipelines.

9. A method for selectively etching a substrate, the method comprising: exposing a substrate in a processing space of a processing chamber to a flow of at least one etch gas from at least one gas reservoir on a processing chamber cover for an etch time, the substrate having a first material and a second material, the at least one gas reservoir being connected to the processing chamber cover via a quick-switch valve, the at least one etch gas selectively etching a third material from the first material with respect to the second material; and purifying the etch gas in the processing space.

10. The method according to claim 9, wherein the etch time is less than or equal to 3 seconds.

11. The method according to claim 9, wherein the at least one gas reservoir is located within a minimum distance from the processing space to ensure an etch cycle of less than 3 seconds.

12. The method according to claim 9, wherein the at least one gas reservoir has a volume greater than or equal to 100 cc.

13. The method according to claim 9, wherein there are two gas reservoirs.

14. The method according to claim 13, wherein the two gas reservoirs contain different etchants.

15. The method according to claim 14, wherein the etch gas comprises a mixture of two etchants flowing into the processing chamber from the two gas reservoirs respectively.

16. The method according to claim 14, wherein each of the gas reservoirs comprises a predetermined mixture of reactants and carrier gas.

17. The method according to claim 14, wherein each gas reservoir pipeline has a length of less than or equal to 20 cm.

18. The method according to claim 14, further comprising: A flow of a processing gas is provided from a gas box connected to the processing chamber into the processing space of the processing chamber, the gas box being configured to provide the flow of the processing gas into the processing space separated from each of the gas storage pipelines.

19. A processing chamber, comprising: a chamber body having side walls and a bottom; a cover on the chamber body, the cover enclosing a processing space; a processing gas inlet in one or more of the chamber body or the cover, the processing gas inlet being configured to provide a flow of a processing gas into the processing space; a first gas storage connected to and in fluid communication with the cover through a quick-switch valve and a first gas storage pipeline, the first gas storage having a first etching gas including a predetermined mixture of an etchant and a carrier gas; and a second gas storage connected to and in fluid communication with the cover through the quick-switch valve and a second gas storage pipeline, the second gas storage having a second etching gas including a predetermined mixture of an etchant and a carrier gas, wherein each of the first gas storage and the second gas storage has a volume sufficient to maintain a constant high-level flow of the etchant into the processing space during a pulse of less than or equal to 3 seconds in total.

20. The processing chamber according to claim 19, further comprising a controller configured to control the gas flow from the first gas storage, the gas flow from the second gas storage, and the gas flow through the processing gas inlet and the quick-switch valve.

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