Method for forming topology-controlled amorphous carbon polymer films

Abstract

To provide, generally, a method of forming a topology-controlled amorphous carbon film on a patterned recess of a substrate.SOLUTION: A method of forming a topology-controlled layer on a patterned recess of a substrate includes: (i) depositing a Si-free C-containing film having filling capability on the patterned recess of the substrate by pulse plasma-assisted deposition to fill the recess in a bottom-up manner or bottomless manner; and (ii) subjecting the bottom-up or bottomless film filling the recess to plasma aching to remove a top portion of the filled film in a manner leaving primarily or substantially only a bottom portion of the filling film or primarily or substantially only a sidewall portion of the filling film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention generally relates to a method for forming a topology-controlled amorphous carbon film over patterned recesses in a substrate. [Background technology]

[0002] 2. Description of Related Art Processes for fabricating integrated circuits, e.g., for shallow trench isolation, intermetal dielectric layers, passivation layers, etc., often require filling trenches (any recess that typically has an aspect ratio of 1 or greater) with insulating materials. However, as the interconnect pitch of large-scale integrated (LSI) devices shrinks, void-free filling of high aspect ratio spaces (e.g., AR ≥ 3) becomes increasingly difficult due to limitations of existing deposition processes.

[0003] In view of the above, the present inventors have developed a gap-fill technique for the deposition of flowable films, which is disclosed in U.S. Patent Application No. 16 / 026,711, filed July 3, 2018, that provides complete gap-fill by plasma-assisted deposition using hydrocarbon precursors without substantial void formation under conditions where nitrogen, oxygen, and hydrogen plasmas are not required, the disclosure of which is incorporated herein by reference in its entirety.

[0004] However, if a particular application, for example where a sacrificial etch stop layer or protective layer is only required at the bottom of a recess, requires bottom-only deposition of amorphous carbon using the above gap-filling techniques in trenches of a substrate, the following problems may arise: i) a certain amount of film (small but not negligible) may be deposited on the top surface of the substrate, ii) the amount of film deposited at the bottom of each trench may be irregular depending on the structural volume of each trench (see FIG. 8(a)), and iii) there may be some randomness in the gap-filling even if the structural volume of each trench is similar (see FIG. 8(b)). The inventors herein provide a solution to the above problems.

[0005] In other applications, such as 3D NAND flash, ultra-deep hole straight etching is required. However, it is very difficult to keep the straight structure intact because sidewall etching occurs during hole etching, resulting in poor CD integrity. The inventors have found that the above gap-filling technique can provide a solution to the above problem.

[0006] Any discussion of problems and solutions relating to the related art is included in this disclosure merely for the purpose of providing a background for the invention and should not be construed as an understanding that any or all of the discussion was known at the time the invention was made. Summary of the Invention [Means for solving the problem]

[0007] In view of the above, some embodiments provide a method of forming a topology control layer on a patterned recess of a substrate, the method including: (i) depositing a Si-free C-containing film having filling capability on the patterned recess of the substrate by pulsed plasma assisted deposition to fill the recess in a bottom-up or bottomless manner; and (ii) plasma ashing the bottom-up or bottomless film filled in the recess to remove a top portion of the fill film in a manner that leaves mainly only the bottom portion of the fill film or mainly only the sidewall portion of the fill film. According to the above embodiments, the topology of the film can be manipulated by using gap-filling techniques. The degree of flowability of the film relative to the size of the trench can mainly determine whether the deposition is a bottom-up or bottomless deposition.

[0008] If the flowability of the film is sufficiently high for the target trench, bottom-up deposition can occur, completely filling the trench, and then by depositing the film on the trench and then plasma ashing the film, the top portion of the film on the trench and the top portion of the film filling into the trench can be equally removed to a uniform depth of the trench, resulting in a trench filled with the film having a substantially uniform depth.

[0009] If the film fluidity is low enough for the target trench, bottomless deposition occurs, but because the film is fluid, even if the film does not reach the bottom of the trench and closes the top opening of the trench, the film can still be deposited along the sidewall of the trench to cover the sidewall to a certain depth from the top surface of the substrate. After the film deposition is completed, the film can be plasma ashed to remove the portion of the film that closes the trench opening, opening the trench and leaving the sidewall film as a space. Then, ultra-deep hole straight etching can be performed. The bottom of the trench is substantially not covered by the film, and the sidewall film can prevent the sidewall from being etched during the ultra-deep hole straight etching, so that the etching can proceed in the depth direction to form the ultra-deep hole straight without compromising the CD integrity.

[0010] In order to summarize aspects of the present invention and advantages achieved over the related art, some objects and advantages of the present invention are described in this disclosure. Of course, it should be understood that not all such objects or advantages may be achieved by any particular embodiment of the present invention. Thus, for example, a person skilled in the art will recognize that the present invention can be embodied or performed in a manner that achieves or optimizes one or a group of advantages taught herein, without necessarily achieving other objects or advantages taught or suggested herein.

[0011] Further aspects, features, and advantages of the present invention will become apparent from the following detailed description.

[0012] These and other features of the present invention will now be described with reference to drawings of preferred embodiments which are intended to be illustrative and not limiting of the invention, and which have been greatly simplified for illustrative purposes and are not necessarily to scale. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1A is a schematic diagram of a PEALD (plasma enhanced atomic layer deposition) apparatus for depositing a dielectric film that can be used in one embodiment of the present invention, and FIG. 1B is a schematic diagram of a precursor delivery system using a flow path system (FPS) that can be used in one embodiment of the present invention. [Diagram 2] FIG. 1 illustrates schematic cross-sectional views of bottom-up deposited ((a)→(b)→(c)) and bottomless deposited ((a)→(d)→(e)) trenches according to embodiments of the present invention. [Diagram 3] 1A-1C are STEM images of cross-sections of trenches subjected to bottom-up deposition (a) followed by O2 / Ar ashing (b) or N2 / H2 ashing (c) according to an embodiment of the invention. [Figure 4] FIG. 1 is a schematic diagram of a STEM photograph of a cross section of a trench obtained by bottomless deposition (300 cycles) without ashing. [Diagram 5] FIG. 1 is a schematic diagram of a STEM photograph of a cross section of a trench subjected to bottomless deposition (300 cycles) followed by ashing (90 seconds) according to an embodiment of the present invention. [Figure 6] FIG. 1 is a schematic diagram of a STEM photograph of a cross section of a trench obtained by bottomless deposition (350 cycles) without ashing. [Figure 7] FIG. 1 is a schematic diagram of a STEM photograph of a cross section of a trench subjected to bottomless deposition (350 cycles) followed by ashing (90 seconds) according to an embodiment of the present invention. [Figure 8] STEM images of cross-sections of bottom-up deposited trenches, (a) showing trenches with different widths and (b) a trench filled with irregular amounts of film. [Figure 9]1A-1B are STEM images of cross sections of bottom-up deposited trenches, (a) representing the trench upon completion of deposition and (b) representing the trench after ashing according to an embodiment of the invention. [Figure 10] 1 is a STEM photograph of cross sections of trenches that have been bottom-up deposited (fully filled) according to an embodiment of the invention, where row (a) represents a mix of wide and narrow trenches with different widths (scale represents 300 nm), row (b) represents an intermediate trench (scale represents 60 nm), and row (c) represents a wide trench with a slightly different width (scale represents 60 nm); column (1) represents a trench that has been fully filled deposited (210 cycles of deposition) before ashing, column (2) represents a trench after 105 seconds of ashing, column (3) represents a trench after 129 seconds of ashing, and column (4) represents a trench after 165 seconds of ashing. [Figure 11] 1A-C are STEM images of cross sections of bottom-up deposited trenches according to one embodiment of the present invention, where (a) represents the trench at the completion of full-fill deposition (210 cycles of deposition), (b) represents the trench after 240 seconds of ashing, and (c) represents the trench after 300 seconds of ashing. [Figure 12] FIG. 1 illustrates a process sequence of film formation according to an embodiment of the present invention, where grey cells represent an ON state while white cells represent an OFF state, and the width of each column does not represent the duration of each process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In the present disclosure, a "gas" can include vaporized solids and / or liquids and can be comprised by a single gas or a mixture of gases, depending on the context. Similarly, the article "a" or "an" refers to a species or genus, including multiple species, depending on the context. In the present disclosure, the process gas introduced into the reaction chamber through the showerhead can be comprised of, consist essentially of, or consist of silicon-free hydrocarbon precursors and additive gases. The additive gas can include a plasma generating gas for exciting the precursors to form an amorphous carbon polymer when RF power is applied to the additive gas. The additive gas can be an inert gas that can be supplied to the reaction chamber as a carrier gas and / or dilution gas. The additive gas can be free of a reactive gas for oxidizing or nitriding the precursors. Alternatively, the additive gas can include a reactive gas for oxidizing or nitriding the precursors to the extent that it does not interfere with the plasma polymerization to form the amorphous carbon-based polymer. Furthermore, in some embodiments, the additive gas includes only a plasma generating gas (e.g., a noble gas). The precursors and additive gas can be introduced into the reaction space as a mixed gas or separately. The precursors can be introduced with a carrier gas, e.g., a noble gas. A gas other than the process gas, i.e., a gas introduced without passing through a showerhead, can be used, for example, to seal the reaction space with a seal gas, e.g., a noble gas. In some embodiments, the term "precursor" generally refers to a compound involved in a chemical reaction that produces another compound, particularly a compound that constitutes the membrane matrix or the backbone of the membrane, and the term "reactant" refers to a compound other than the precursor that activates, modifies, or catalyzes the reaction of the precursor, and in an excited state, the reactant can provide elements (e.g., O, C, N) to the membrane matrix and become part of the membrane matrix. The term "plasma generating gas" refers to a compound other than the precursor and reactant that generates a plasma when exposed to electromagnetic energy, and the plasma generating gas may not provide elements (e.g., O, C, N) to the membrane matrix that become part of the membrane matrix.The term "plasma ashing gas" refers to a gas that ashes a film while excited either by direct current (DC plasma) or remotely (remote plasma). In some embodiments, the "plasma ashing gas" is a single gas or a mixture of two or more gases. The term "ashing" refers to the use of plasma to remove organic matter, leaving mineral components as a residue (ash) that is usually removed by a vacuum pump.

[0015] In some embodiments, a "film" refers to a layer that extends continuously in a direction perpendicular to the thickness direction without substantially pinholes to cover the entire object or relevant surface, or simply a layer that covers the object or relevant surface. In some embodiments, a "layer" refers to a structure having a particular thickness formed on a surface, or a synonym of a film, or a structure that is not a film. A film or layer may be composed of a separate single film or layer, or multiple films or layers, having particular properties, and the boundaries between adjacent films or layers may or may not be distinct and are indicated based on any physical, chemical, and / or other characteristics, formation process or sequence, and / or function or purpose of adjacent films or layers. Furthermore, in the present disclosure, since a feasible range can be determined based on routine practice, any two variables can constitute a feasible range for that variable, and any range indicated can include or exclude endpoints. In some embodiments, further, any value of an indicated variable (whether or not they are indicated as "about") may refer to an exact value or an approximate value, including equivalents, mean, median, representative, or majority, etc. Additionally, in this disclosure, the terms "comprised of" and "having" may, in some embodiments, independently refer to "typically or broadly including," "comprising," "consisting essentially of," or "consisting of." In this disclosure, any defined meaning does not necessarily exclude the ordinary and customary meaning in some embodiments.

[0016] In this disclosure, "continuously" refers to without breaking vacuum, without interruption in the time sequence, without any intervening material steps, without changing processing conditions immediately following a subsequent step, or, in some embodiments, without any intervening distinct physical or chemical structures between the two structures other than the two structures themselves.

[0017] In this disclosure, the term "filling ability" (also referred to as "flowability") refers to the ability to fill gaps substantially void-free (e.g., no voids having a size of about 5 nm or greater in diameter) and seamlessly (e.g., no seams with a length of about 5 nm or greater), such that when depositing a film in a wide trench with an aspect ratio of about 1 or greater, a seamless / void-free bottom-up grown layer is observed.

[0018] Flow often manifests as a concave surface of the film at the bottom of a wide trench before it is filled, and also as a nearly planar top surface of the film (planarization) if the film is deposited continuously after it has completely filled the trench. Such deposition is called "bottom-up deposition."

[0019] If the trench is narrow and deep, even if the film is flowable, the film may not be able to reach the bottom of the trench. In that case, flowability often manifests as a rough or substantially conformal film along the sidewalls of the trench with substantially no film at the bottom of the trench and typically with the top opening of the trench closed by the film. Because the film is flowable, the sidewall film flows and extends downward along the sidewalls, thereby forming a thin film, and the ratio of the average thickness of the substantially conformal portion of the film (excluding the top portion closing the top opening of the trench, which is substantially removed by ashing) to the depth of the film in the trench (the length extending along the sidewalls toward the bottom) can range from 0.1% to 10% (typically 0.5%-5%). Such a deposition is referred to as a "bottomless deposition".

[0020] In the present disclosure, the recess between the adjacent protruding structure and any other recess pattern is called a "trench". That is, a trench is any recess pattern that includes a hole / via. For bottom-up deposition, in some embodiments, the trench has a width (if the length of the trench is substantially the same as the width, it is called a hole / via) of about 20 nm to about 100 nm (usually about 30 nm to about 50 nm), a depth of about 30 nm to about 100 nm (usually about 40 nm to about 60 nm), and an aspect ratio of about 2 to about 10 (usually about 2 to about 5). For bottomless deposition, in some embodiments, the trench has a width (CD) of about 5.5 nm to about 200 nm (usually about 10 nm to about 100 nm), a depth of about 800 nm to about 10,000 nm (usually about 300 nm to about 8,000 nm), and an aspect ratio of about 15 to about 150 (usually about 20 to about 100). The appropriate dimensions of the trench can vary depending on the process conditions, film flowability, film composition, the given application, etc. By adjusting the film flowability, for example, bottom-up deposition and bottomless deposition can be achieved in trenches having different sizes than those mentioned above.

[0021] In this disclosure, the terms "substantially no deposition," "substantially no film," and the like refer to an amount functionally equivalent to zero, an insignificant or negligible amount, an amount that does not substantially interfere with subsequent processes (e.g., ashing), less than a detectable or observable amount, and the like.

[0022] In this disclosure, a defined meaning does not necessarily exclude, in some embodiments, the ordinary and customary meaning. Also, in this disclosure, "invention" or "the present invention" refers to at least one of the embodiments or aspects explicitly, necessarily, or inherently disclosed herein.

[0023] The embodiments are described in terms of preferred embodiments, however, it is not intended that the invention be limited to the preferred embodiments.

[0024] Some embodiments provide a method for forming a topology control layer in a patterned recess of a substrate, the method including: (i) depositing a Si-free C-containing film having filling capability on the patterned recess of the substrate by pulsed plasma-assisted deposition to fill the recess in a bottom-up or bottomless manner; and (ii) plasma ashing the bottom-up or bottomless film filled in the recess to remove a top portion of the filling film in a manner that leaves mainly only the bottom portion of the filling film or mainly only the sidewall portion of the filling film. The Si-free C-containing film can be an amorphous carbon polymer film, which is usually a flowable film. When the amorphous carbon polymer film is formed using a plasma-assisted method, the resulting amorphous carbon polymer film is made of a hydrogenated amorphous carbon polymer. In this disclosure, the hydrogenated amorphous carbon polymer may simply refer to an amorphous carbon polymer, and may also be referred to as an abbreviation "aC:H" or simply "aC". Furthermore, in this specification, unless otherwise specified, SiC, SiCO, SiCN, SiCON, etc. are abbreviations that non-stoichiometrically indicate film types (simply indicated by main constituent elements).

[0025] In some embodiments, in step (i), a Si-free C-containing film is deposited using a hydrocarbon precursor. In some embodiments, step (i) comprises: (ia) supplying a precursor to a reaction space in which a substrate is disposed; and (ib) exposing a patterned recess of the substrate to a plasma to deposit a Si-free C-containing film in the patterned recess, where step (ib) is performed intermittently in a manner of pulsing the plasma, and step (ia) is performed continuously or intermittently without overlapping with step (ib) as a process prerequisite for step (ib). In some embodiments, the Si-free C-containing film is substantially composed of a hydrocarbon.

[0026] Deposition of flowable films is known in the art. However, conventional deposition of flowable films uses chemical vapor deposition (CVD) with constant application of RF power, since pulsed plasma assisted deposition, e.g. PEALD, is well known to deposit conformal films, which are films with properties exactly opposite to those of flowable films. In some embodiments, the flowable film is a silicon-free carbon-containing film consisting of amorphous carbon polymers, and while any suitable one or more of the hydrocarbon precursors may be candidates, in some embodiments the precursor comprises an unsaturated or cyclic hydrocarbon having a vapor pressure of 1,000 Pa or more at 25° C. In some embodiments, the precursor comprises a C2-C8 alkyne (C n H 2n-2 ), C2-C8 alkenes (C n H 2n ), C2-C8 dienes (C n H n+2 ), C3-C8 cycloalkenes, C3-C8 annulenes (C n H n ), C3-C8 cycloalkanes, and at least one compound selected from the group consisting of substituted hydrocarbons as described above. In some embodiments, the precursor is ethylene, acetylene, propene, butadiene, pentene, cyclopentene, benzene, styrene, toluene, cyclohexene, and / or cyclohexane.

[0027] In some embodiments, a gap-fill technique for the deposition of flowable films can be the method disclosed in U.S. Patent Application Serial No. 16 / 026,711, which provides complete gap-fill by plasma-assisted deposition using hydrocarbon precursors without substantial void formation under conditions where nitrogen, oxygen, or hydrogen plasma is not required, and the disclosure of which is incorporated herein by reference in its entirety.

[0028] A non-flowable film can be formed by modifying the deposition conditions or process parameters. For example, such parameters include, but are not limited to, the partial pressure of the precursor, the deposition temperature, the deposition pressure, etc. For example, increasing the deposition temperature, decreasing the deposition pressure, and / or decreasing the precursor ratio (ratio of precursor flow rate to carrier gas / dilution gas flow rate) makes the film less flowable. In some embodiments, process (i) (the deposition process) is performed by plasma enhanced atomic layer deposition (PEALD) or other cyclic plasma assisted deposition (e.g., cyclic PECVD). The plasma can be capacitively coupled plasma, inductively coupled plasma, remote plasma, RF power generated plasma, microwave generated plasma, etc.

[0029] In some embodiments, the plasma ashing in step (ii) is performed using a direct current or remote oxygen or hydrogen plasma. In some embodiments, the direct current or remote oxygen or hydrogen plasma may be H2 alone, a mixture of Ar and H2 (Ar / H2 flow ratio 0.005-0.995, typically 0.05-0.75), a mixture of He and H2 (He / H2 flow ratio 0.005-0.995, typically 0.05-0.75), a mixture of N2 and H2 (N2 / H2 flow ratio 0.005-0.995, typically 0.05-0.75), or a mixture of H2. , a direct current or remote plasma of a gas selected from the group consisting of O2 only, a mixture of O2 and Ar (O2 / Ar flow ratio 0.005-0.995, typically 0.05-0.75), a mixture of O2 and He (O2 / He flow ratio 0.005-0.995, typically 0.05-0.75), and a mixture of O2 and N2 (O2 / N2 flow ratio 0.005-0.995, typically 0.05-0.75).

[0030] In some embodiments, the aspect ratio of the recess is in the range of 10-150 (usually 15-100), the depth of the recess is greater than 200 nm, the recess is filled with a film in a bottomless manner in step (i), and a top portion of the filled film blocks a top opening of the recess. In some embodiments, plasma ashing is performed in step (ii) to open the blocked top portion of the recess, leaving primarily or substantially only the sidewall portion of the filled film.

[0031] In some embodiments, the substrate has a plurality of recesses with an aspect ratio of 2-30 (usually 3-20), and the recesses are filled with a film in a bottom-up manner in step (i), with a surface topology that varies due to loading effects. In some embodiments, step (i) continues until planarization of the film over the plurality of recesses occurs, and then plasma ashing is performed in step (ii) to homogenize the surface topology of the film filled in the plurality of recesses and leave mainly or substantially only the bottom of the filled film.

[0032] The embodiments will be described with reference to the drawings, but the present invention is not intended to be limited to the drawings.

[0033] FIG. 2 illustrates schematic cross-sectional views of bottom-up deposited ((a)→(b)→(c)) and bottomless deposited ((a)→(d)→(e)) trenches according to an embodiment of the present invention. First, in FIG. 2(a), a substrate having a trench is provided, where in the case of bottom-up deposition, the substrate 21 has a trench 20 having a width wide enough to allow the flowable film to flow into the trench and a depth small enough to allow the flowable film to reach the bottom of the trench 20, while in the case of bottomless deposition, the substrate 31 has a trench 30 having a width wide enough to allow the flowable film to flow into the trench, but narrow enough to block the top opening of the trench 30 with the film before the film reaches the bottom of the trench 30, and a depth deep enough to prevent the flowable film from reaching the bottom of the trench 30. For example, suitable sizes of the trenches are described in this disclosure and can be selected according to the flowability of the film. It should be noted that FIG. 2 is overly simplified and not to scale.

[0034] Next, in the deposition process, the same deposition process conditions can be used for both bottom-up deposition in (b) and bottomless deposition in (d), except for the number of deposition cycles, duration of ashing, etc., and the deposition process conditions are changed according to the size of the trench, the target deposition thickness of the film, the target ashing amount, the target final topology of the film, etc. In (b), the flowable film fills the trench 20 in a bottom-up manner, and after completely filling the trench 20, it is continuously deposited on the substrate 21 until the top surface of the film 22 is planarized. Planarization can be achieved due to the flowability of the film. In (d), the flowable film is deposited on the top of the substrate 31, flows into the trench 30, and moves downward along the sidewall of the trench 30 in a bottomless manner, blocking the top opening of the trench 30 with the flowable film 32. The flowable film flows downward along the sidewall of the trench 30, for example, with an aspect ratio of about 10 to 100, so that the film on the sidewall is substantially conformal along the sidewall and can function as a spacer. It should be noted that bottom-up and bottomless depositions can be performed on the same sized trenches by tailoring the film's fluidity from deposition to deposition, for example using the fluidity tailoring method disclosed in U.S. Patent Application Serial No. 16 / 026,711.

[0035] Next, in an ashing step, the amorphous carbon constituting the film is removed (ashed) from the top surface exposed to the plasma to a depth suitable for a bottom-only topology or a sidewall-only topology. In (c), by removing the portion of the film 22 deposited on the top surface of the substrate 21 and the upper portion of the film 22 filling the trench 20 in a bottom-up manner, a film 23 having a bottom-only topology can be obtained, which has a homogeneous and approximately uniform depth. In (e), by removing the portion of the film 32 deposited on the top surface of the substrate 31 and the upper portion of the film 32 filling the upper opening of the trench 30 in a bottomless manner, a film 33 having a sidewall-only topology can be obtained, which has a homogeneous and approximately uniform thickness.

[0036] As disclosed in US Patent Application Serial No. 16 / 026,711, in some embodiments, the deposition process preferably uses an ALD-like recipe (e.g., feed / purge / plasma strike / purge), where the post-feed purge is spontaneously significantly shortened to leave a high partial pressure of precursor during plasma strike. This is clearly distinct from the ALD chemistry and mechanism. Although an ALD-like recipe can be more beneficial as explained later, the above process can be based on pulsed plasma CVD, which also provides good filling capabilities to the resulting films.

[0037] In some embodiments, unlike traditional ALD, important aspects regarding the flowability of the deposited film include:

[0038] 1) A sufficiently high partial pressure during the entire RF-ON period for polymerization / chain growth to proceed;

[0039] 2) Enough energy to activate the reaction (defined by RF-ON duration and RF power), but not an excessively long RF-ON duration;

[0040] 3) Temperature and pressure for polymerization / chain propagation set above the melting point of the flowable phase but below the boiling point of the material being deposited.

[0041] In some embodiments, the process parameter ranges are adjusted to adjust the film flowability as follows:

[0042] [Table 1]

[0043] With regard to pressure, gravity and surface tension are the driving forces for flowing the film at the bottom, so high pressure is favored for fluidity. With regard to temperature, low temperature is favored for fluidity (this is counterintuitive), but high temperature favors the chain growth rate of the polymer.

[0044] 12 is a diagram illustrating a process sequence for film formation according to an embodiment of the present invention, where gray cells represent an ON state while white cells represent an OFF state, and the width of each column does not represent the duration of each process. This simplified process sequence can be applied to both bottom-up and bottomless deposition, and in some embodiments, the same deposition process conditions can be used for both bottom-up and bottomless deposition, except for the number of deposition cycles, duration of ashing, etc., which are modified depending on the size of the trench, the target deposition thickness of the film, the target ashing amount, the target final topology of the film, etc.

[0045] The process sequence includes a deposition process ("Delivery" → "Purge" → "RF Pulse-1" (plasma polymerization) → "Purge") and a plasma ashing process ("Stabilization" → "RF Pulse-2" (plasma ashing) → "Purge"). The plasma polymerization process includes depositing an amorphous carbon polymer film on a substrate having a trench by PEALD-like deposition using a Si- and metal-free C-containing precursor and a plasma generating gas that generates a plasma by applying RF power (RF) between two electrodes with the substrate arranged in parallel with the two electrodes, and RF power is applied in each sublayer deposition cycle of the PEALD-like deposition, and the plasma generating gas and carrier gas flow continuously and also serve as a purge gas during "purge" after "Delivery" and during "purge" after "RF Pulse-1".

[0046] In some embodiments, for a 300 mm wafer (for different size wafers, the wattages below are per unit area (cm 2(applied as W per kW), feed time ranges from 0.3 to 10 seconds (usually 0.6 to 2 seconds), post-feed purge time ranges from 0 to 0.5 seconds (usually 0 to 0.3 seconds), RF time ranges from 0.5 to 2 seconds (usually 0.8 to 1.5 seconds), post-RF purge time ranges from 0 to 0.5 seconds (usually 0 to 0.1 seconds), carrier gas flow rate ranges from 0 to 0.8 slm (usually 0.1 to 0.3 slm), plasma generating gas flow rate ranges from 0 to 0.5 slm (usually 0.1 to 0.3 slm), and RF power ranges from 50 to 400 W (usually 75 to 200 W).

[0047] The fluidity of the film is obtained temporarily, for example, when a volatile hydrocarbon precursor is polymerized by the plasma and deposited on the surface of the substrate. The gaseous monomers (precursors) are activated or fragmented by the energy provided by the plasma gas discharge to initiate polymerization, and when the resulting polymeric material is deposited on the surface of the substrate, it exhibits a temporarily fluid behavior. Once the deposition process is complete, the fluid film is no longer fluid and solidifies, so that a separate solidification process is not required.

[0048] The deposition process is a process similar to PEALD, and one cycle of it to form a sublayer (usually thicker than a monolayer) is repeated q times until a desired thickness of the amorphous carbon polymer film is obtained before starting the plasma ashing process, where q is an integer between 5 and 100 (preferably between 25 and 50) for bottom-up deposition depending on the size of the trench, the use of the film, etc., to deposit an amorphous carbon polymer film having a thickness between 2.5 nm and 50 nm (preferably between 7.5 nm and 25 nm) on the top surface of the substrate before starting the plasma ashing process, and where q is an integer between 10 and 200 (preferably between 40 and 100) for bottomless deposition depending on the size of the trench, the use of the film, etc., to deposit an amorphous carbon polymer film having a thickness between 5 nm and 100 nm (preferably between 20 nm and 50 nm) on the top surface of the substrate before starting the plasma ashing process.

[0049] Next, the plasma ashing process begins, which involves supplying an ashing gas (H2 or O2, or mixtures of the aforementioned gases with N2, Ar, and / or He) to the reaction space ("Stabilization"), which is excited by radio frequency power (RF) to generate a plasma to ash the amorphous carbon polymer film ("RF Pulse 2"), followed by purging ("Purge"), with the ashing gas being continuously supplied to the reaction space throughout the plasma ashing process. In some embodiments, the RF power for plasma ashing is in the range of 50-500 W (typically 50-200 W) for a duration of 5-200 s (typically 10-100 s) under a pressure of 100 Pa-1000 Pa (typically 200-600 Pa), with a stabilization time in the range of 5-60 s (typically 10-30 s), a post-RF purge time in the range of 5-60 s (typically 10-30 s), and an ashing gas flow rate in the range of 0.1-10 slm (typically 0.5-2 slm).

[0050] In some embodiments, the carrier gas is continuously supplied to the reaction space throughout the process, for example, in the range of 0 sccm to 2000 sccm (preferably 100 sccm to 500 sccm), and the process temperature can be in the range of -50°C to 175°C (preferably 35°C to 150°C).

[0051] The plasma generating gas in the deposition process and the ashing gas in the plasma ashing process may be the same or different, for example, both may be Ar and / or He.

[0052] A continuous flow of carrier gas can be achieved using a flow path system (FPS), which provides a bypass line with a precursor reservoir (bottle) in the carrier gas line and switches between the main line and the bypass line. When only carrier gas is intended to be supplied to the reaction chamber, the bypass line is closed, while when both carrier gas and precursor gas are intended to be supplied to the reaction chamber, the main line is closed, and the carrier gas flows through the bypass line and exits the bottle together with the precursor gas. In this way, the carrier gas can flow continuously into the reaction chamber, and the precursor gas can be delivered in pulses by switching between the main line and the bypass line. FIG. 1B illustrates a precursor delivery system using a flow path system (FPS) according to an embodiment of the present invention (black valve indicates that the valve is closed). As shown in FIG. 1B (a), when a precursor is to be supplied to a reaction chamber (not shown), first, a carrier gas, for example, Ar (or He), flows through a gas line with valves b and c, and enters a bottle (reservoir) 26. The carrier gas flows out of the bottle 26 carrying the precursor gas in an amount according to the vapor pressure in the bottle 26, flows through a gas line having valves f and e, and is supplied to the reaction chamber together with the precursor. In the above, valves a and d are closed. When only the carrier gas (noble gas) is supplied to the reaction chamber, the carrier gas flows through the gas line having valve a while bypassing the bottle 26, as shown in (b) of FIG. 1B. In the above, valves b, c, d, e, and f are closed.

[0053] The process cycle can be carried out using any suitable apparatus, including, for example, the apparatus shown in FIG. 1A. FIG. 1A is a schematic diagram of a PEALD apparatus usable in some embodiments of the present invention, preferably integrated with a controller programmed to execute the sequence described below. In this figure, a pair of conductive flat electrodes 4, 2 are provided in parallel facing each other in the interior 11 (reaction region) of a reaction chamber 3, and a plasma is excited between the electrodes by applying HRF power (13.56 MHz or 27 MHz) 25 to one side and electrically grounding the other side 12. A temperature regulator is provided on the lower stage 2 (lower electrode), and the temperature of a substrate 1 placed thereon is kept constant at a predetermined temperature. The upper electrode 4 also functions as a shower plate, and reactant gases and / or dilution gases, if any, and precursor gases are introduced into the reaction chamber 3 through gas lines 27 and 28, respectively, and through the shower plate 4. In addition, a circular duct 13 having an exhaust line 7 is provided in the reaction chamber 3, through which gases in the interior 11 of the reaction chamber 3 are exhausted. Furthermore, the transfer chamber 5 disposed below the reaction chamber 3 is provided with a seal gas line 24 for introducing a seal gas into the interior 11 of the reaction chamber 3 through the interior 16 (transfer zone) of the transfer chamber 5. A separation plate 14 is provided for separating the reaction zone from the transfer zone (the gate valve through which the wafer is transferred into and out of the transfer chamber 5 is omitted from this figure). The transfer chamber is also provided with an exhaust line 6. In some embodiments, the deposition of the multi-element film and the surface treatment are performed in the same reaction space, so that all steps can be performed continuously without exposing the substrate to air or other oxygen-containing atmosphere.

[0054] In some embodiments, the apparatus shown in FIG. 1A can be used to introduce pulses of precursor gas without substantially fluctuating the pressure in the reaction chamber using a system for switching between inert gas flow and precursor gas flow as illustrated in FIG. 1B (described above).

[0055] Those skilled in the art will appreciate that the apparatus includes one or more controllers (not shown) programmed or otherwise configured to carry out the deposition and reactor cleaning processes described elsewhere herein. As will be appreciated by those skilled in the art, the controller is in communication with the various power sources, heating systems, pumps, robotics, and gas flow controllers or valves of the reactor.

[0056] In some embodiments, a dual chamber reactor (two zones or compartments for processing wafers placed in close proximity to each other) can be used, and reactant gases and noble gases can be supplied through shared lines, while precursor gases are supplied through non-shared lines.

[0057] The films with filling capabilities can be applied in various semiconductor devices, including but not limited to cell isolation in 3D cross-point memory devices, self-aligned vias, dummy gates (replacing current poly-Si), reverse tone patterning, PC RAM isolation, cut hard mask, and DRAM storage node contact (SNC) isolation.

[0058] Working Example In the following examples where conditions and / or structures are not specified, one of skill in the art can readily provide such conditions and / or structures in light of the present disclosure as a matter of routine experimentation. One of skill in the art will understand that the apparatus used in the examples includes one or more controllers (not shown) programmed or otherwise configured to carry out the deposition and reactor cleaning processes described elsewhere herein. As will be appreciated by one of skill in the art, the controllers are in communication with the various power sources, heating systems, pumps, robots, and gas flow controllers or valves of the reactor.

[0059] Reference example 1 (Figure 3) Amorphous carbon polymer films were deposited on a Si substrate (diameter 300 mm, thickness 0.7 mm) having a trench with an opening of about 25-35 nm and a depth of about 85 nm (aspect ratio is about 2.4-3.4) by a process similar to PEALD using the apparatus illustrated in FIG. 1A and the gas supply system (FPS) illustrated in FIG. 1B in a bottom-up manner according to the process sequence shown in FIG. 12 under the conditions shown in Table 2 below. The film was deposited to completely fill the trench, and further deposited on top to form a flat top surface. The same cycle as PEALD was repeated 242 times (p=242). Then, successive ashing was performed using a mixture of O2 and Ar or a mixture of N2 and H2 under the conditions shown in Table 2 below according to the process sequence shown in FIG. 12.

[0060] [Table 2]

[0061] Figure 3 shows STEM images of the cross-sections of trenches that were deposited bottom-up (a) followed by O2 / Ar ashing (b) or N2 / H2 ashing (c). As shown in Figure 3, the amorphous carbon polymer film is effectively flowable, completely filling all trenches (regardless of size difference) and can be further deposited on top to form a flat top surface, and the amorphous carbon polymer film can be completely removed or ashed away by the ashing process without compromising the CD integrity. That is, by manipulating the ashing time, a desired amount of the amorphous carbon polymer film can be removed without compromising the CD integrity.

[0062] Example 1 An amorphous carbon polymer film was deposited on a Si substrate (diameter 300 mm, thickness 0.7 mm) having a trench with an opening of about 20 nm and a depth of about 200 nm (aspect ratio was about 10) under the same conditions as in Reference Example 1, except that the deposition cycle was repeated 210 times (p=210) by a process similar to PEALD in a bottom-up manner, and the film was deposited to a thickness of 100 nm on the top surface of the substrate. Then, ashing was performed continuously using a mixture of O2 and Ar as in Reference Example 1, except that the RF time was shortened to 90 seconds to form a film structure with a topology only at the bottom, and the film was ashed to a depth of 181 nm from the top surface of the substrate.

[0063] Figure 9 shows STEM images of the cross-sections of bottom-up deposited trenches, where (a) represents the trench upon completion of deposition and (b) represents the trench after ashing. As shown in Figure 9, the amorphous carbon polymer film is effectively flowable and completely fills all trenches and is further deposited on top to form a flat top surface, confirming that the ashing process can uniformly remove or ash the amorphous carbon polymer film in all trenches without compromising the CD integrity, forming a homogenous film structure with uniform bottom-only topology.

[0064] Example 2 An amorphous carbon polymer film was deposited on a Si substrate having a trench in the same manner as in Example 1, except that the ashing time was changed.

[0065] FIG. 10 shows STEM images of cross-sections of trenches that were bottom-up deposited (fully filled), where row (a) represents a mix of wide and narrow trenches with different widths (scale represents 300 nm), row (b) represents an intermediate trench (scale represents 60 nm), row (c) represents a wide trench with a slightly different width (scale represents 60 nm), column (1) represents a trench that was fully filled deposited (210 cycles of deposition) before ashing, column (2) represents a trench after 105 seconds of ashing, column (3) represents a trench after 129 seconds of ashing, and column (4) represents a trench after 165 seconds of ashing.

[0066] FIG. 11 shows STEM images of cross sections of bottom-up deposited trenches: (a) represents the trench at the completion of full-fill deposition (210 cycles of deposition), (b) represents the trench after 240 seconds of ashing, and (c) represents the trench after 300 seconds of ashing.

[0067] As shown in Figures 10 and 11, it was confirmed that the amorphous carbon polymer film is effectively flowable, completely fills all trenches, and can be further deposited thereon to form a flat top surface, and that the amorphous carbon polymer film can be uniformly removed or ashed in all trenches by the ashing process without compromising the CD integrity to form a homogenous film structure with uniform bottom-only topology. It was also surprisingly confirmed that the combination of full-fill deposition and ashing can achieve uniform bottom-only deposition with virtually no loading effect.

[0068] Reference example 2 An amorphous carbon polymer film was deposited on a Si substrate (diameter 300 mm, thickness 0.7 mm) having a trench with an opening of about 150 nm and a depth of about 2500 nm (aspect ratio was about 17) under the same conditions as in Reference Example 1, except that the deposition cycle was repeated 350 times (p=350) by a process similar to PEALD in a bottomless manner, and the film was deposited to a thickness of 160 nm on the top surface of the substrate.

[0069] Bottomless deposition is confirmed by STEM photographs of cross-sections of bottomless deposited trenches, including (a) a series of trenches with the film deposited thereon, (b) a close-up of the top of one of the trenches, (c) a close-up of the bottom of the trench, and (d) a close-up of the sidewall of the trench. Although the trench is not completely filled with film as observed in (a), it was confirmed that the amorphous carbon polymer film is effectively flowable, and while the top of the trench is blocked by film (overfilled at the top) as observed in (b), the film flows downward and extends along the sidewall of the trench towards the bottom of the trench as observed in (d), but does not reach the bottom of the trench as observed in (c), forming a substantially conformal (substantially uniform thickness along the sidewall) and homogenous film structure along the sidewall.

[0070] Reference example 3 An amorphous carbon polymer film was deposited on a Si substrate (diameter 300 mm, thickness 0.7 mm) having a trench with an opening of about 140-160 nm and a depth of about 2500 nm (aspect ratio was about 16-18) under the same conditions as in Reference Example 1, except that the deposition cycle was repeated 300 times (p=300) by a process similar to PEALD in a bottomless manner, and the film was deposited to a thickness of 116 nm on the top surface of the substrate.

[0071] FIG. 4 shows a schematic diagram of a STEM photograph of a cross section of a trench that was bottomless deposited (300 cycles) without ashing. As shown in FIG. 4, although the trench was not completely filled with the film, the amorphous carbon polymer film was effectively flowable, and the top of the trench was just or barely blocked with the film (overfilled at the top) and the film was deposited on the top surface of the substrate, but the film flowed downward and extended along the sidewall of the trench toward the bottom of the trench, slightly reaching the bottom of the trench, forming a substantially conformal (substantially uniform thickness along the sidewall) and homogeneous film structure along the sidewall. If the dry etching conditions are set such that the selectivity of the carbon film is high (e.g., >100) compared to the underlayer, the slight deposition of the film at the bottom does not prevent further etching to form an ultra-deep hole, and therefore this deposition is still referred to as a bottomless deposition. Furthermore, by tuning the flowability of the film (slightly reducing the flowability), the flow of the film along the sidewall can be stopped before it reaches the bottom.

[0072] Example 3 An amorphous carbon polymer film was deposited on a Si substrate in a bottomless manner under the same conditions as in Reference Example 3. Then, successive ashing was performed using a mixture of O2 and Ar as in Reference Example 1, except that the RF time was shortened to 90 seconds. A portion of the film deposited on the top surface of the substrate was thinned, and the top-closing portion (overfilled portion) of the film in the trench was removed to open the trench, thereby forming a space-like structure in the trench.

[0073] A schematic STEM image of the cross section of a trench after bottomless deposition (300 cycles) followed by ashing (90 seconds) is shown in Figure 5. As shown in Figure 5, it was confirmed that ashing effectively removes the overfilled top portion of the trench to open the top of the trench without compromising the CD integrity, forming a substantially conformal (substantially uniform thickness along the sidewall) and homogenous film structure along the sidewall.

[0074] Reference example 4 An amorphous carbon polymer film was deposited on a Si substrate in a bottomless manner under the same conditions as in Reference Example 3, except that the deposition cycle was repeated 350 times (p=350). As a result, the film was deposited on the top surface of the substrate to a thickness of 160 nm, completely filling the top opening of the trench (the thickness of the overfilled portion on the trench was 145 nm).

[0075] Figure 6 shows a schematic diagram of a STEM image of a cross section of a trench that was subjected to bottomless deposition (350 cycles) without ashing. As shown in Figure 6, although the trench was not completely filled with the film, it was confirmed that the amorphous carbon polymer film was effectively flowable, the top of the trench was blocked with the film, and the film was deposited on the top surface of the substrate, but the film flowed downward and extended along the sidewall of the trench toward the bottom of the trench, similar to Reference Example 3.

[0076] Example 4 An amorphous carbon polymer film was deposited on a Si substrate in a bottomless manner under the same conditions as in Reference Example 4. Then, successive ashing was performed using a mixture of O2 and Ar as in Reference Example 1, except that the RF time was shortened to 90 seconds. A portion of the film deposited on the top surface of the substrate was thinned and the top closing portion of the film in the trench (overfilled portion) was removed to open the trench, thereby forming a space-like structure in the trench (the thickness of the overfilled portion on the trench was 95 nm).

[0077] A schematic STEM image of the cross section of trenches subjected to bottomless deposition (350 cycles) followed by ashing (90 seconds) is shown in Figure 7. As shown in Figure 7, it was confirmed that ashing effectively removes the top of the overfilled trenches to open the top of each trench without compromising the CD integrity, forming a substantially conformal (substantially uniform thickness along the sidewalls) and homogenous film structure along the sidewalls.

[0078] It will be apparent to those skilled in the art that numerous and various modifications can be made to the present invention without departing from the spirit and scope of the present invention. Therefore, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention. [Explanation of symbols]

[0079] 2, 4 Conductive plate electrode 3. Reaction chamber 5. Transfer chamber 6, 7 Exhaust line 11 Inside the reaction chamber 13 Circular Duct 14 Separation plate 16 Inside the transfer chamber 20, 30 Trench 21, 31 Base material 22, 23, 32, 33 membrane 24 Seal gas line 25 HRF Power 27, 28 Gas lines

Claims

1. 1. A method for forming a film in a patterned recess of a substrate, comprising the steps of: (i) depositing a Si-free C-containing film having filling capability on the recess by PEALD to fill the recess in a bottom-up or bottomless manner; (ii) plasma ashing the C-containing film to remove a top portion of the C-containing film in a manner that leaves primarily or substantially only a bottom portion of the C-containing film, or primarily or substantially only a sidewall portion of the C-containing film.

2. 2. The method of claim 1, wherein the plasma ashing in step (ii) is performed using a direct current or a remote oxygen or hydrogen plasma.

3. 3. The method of claim 2, wherein the direct current or remote oxygen or hydrogen plasma is a direct current or remote plasma of a gas selected from the group consisting of H2 only, a mixture of Ar and H2, a mixture of N2 and H2, a mixture of He and H2, O2 only, a mixture of O2 and Ar, a mixture of O2 and He, and a mixture of O2 and N2.

4. 2. The method of claim 1, wherein in step (i), the Si-free C-containing film is deposited using a hydrocarbon precursor.

5. 2. The method of claim 1, wherein step (i) comprises: (ia) supplying a precursor to a reaction space in which the substrate is disposed; and (ib) exposing the patterned recesses of the substrate to a plasma to deposit the Si-free C-containing film in the patterned recesses, and step (ib) is performed intermittently in a pulsing manner of the plasma, and step (ia) is performed continuously or intermittently without overlap with step (ib) as a process prerequisite for step (ib).

6. The method of claim 1 , wherein the Si-free C-containing film consists essentially of hydrocarbons.

7. 2. The method of claim 1 , wherein an aspect ratio of the recess is in the range of 10 to 100, a depth of the recess is greater than 200 nm, the recess is filled with the C-containing film in a bottomless manner in step (i), and a top portion of the filled C-containing film blocks a top opening of the recess.

8. 8. The method of claim 7, wherein plasma ashing is performed in step (ii) to open the top portion and to leave primarily or substantially only the sidewall portion of the filled film.

9. 2. The method of claim 1, wherein the substrate has a plurality of recesses with an aspect ratio of 2-30, and the recesses are filled with the C-containing film in a bottom-up manner in step (i), and have a surface topology that varies due to a loading effect.

Images