阅读说明：本技术 通过脉冲等离子体辅助沉积将无硅含碳膜沉积为间隙填充层的方法 (Method for depositing silicon-free carbon-containing films as gap-fill layers by pulsed plasma-assisted deposition ) 是由 T·J·V·布兰夸尔特 于 2019-07-01 设计创作，主要内容包括：本公开涉及通过脉冲等离子体辅助沉积将无硅含碳膜沉积为间隙填充层的方法。本公开提供了一种在衬底的表面上填充图案化凹部的方法,包括：在反应空间中提供包括凹部的衬底；向所述反应空间提供无硅含碳前体,从而用气相前体填充所述凹部；以及向所述反应空间提供等离子体,从而在所述凹部中形成粘性材料,其中所述粘性材料在所述凹部中流动且在所述凹部的底部积聚,从而在所述凹部的所述底部形成沉积材料,且其中所述沉积材料凝固。通过使用烃前体的等离子体辅助沉积提供完全间隙填充,在不需要氮、氧或氢等离子体的条件下基本上不形成空隙,解决了现有技术中的一个或多个问题。(The present disclosure relates to methods of depositing silicon-free carbon-containing films as gap fill layers by pulsed plasma-assisted deposition. The present disclosure provides a method of filling a patterned recess on a surface of a substrate, comprising: providing a substrate including a recess in a reaction space; providing a silicon-free carbon-containing precursor to the reaction space, thereby filling the recess with a gas phase precursor; and providing a plasma to the reaction space to form a viscous material in the recess, wherein the viscous material flows in the recess and accumulates at a bottom of the recess to form a deposition material at the bottom of the recess, and wherein the deposition material solidifies. One or more problems of the prior art are addressed by providing complete gap filling using plasma assisted deposition of a hydrocarbon precursor, without substantial void formation under conditions that do not require a nitrogen, oxygen, or hydrogen plasma.)

1. A method of filling a patterned recess on a surface of a substrate, the method comprising:

providing a substrate including a recess in a reaction space;

providing a silicon-free carbon-containing precursor to the reaction space, thereby filling the recess with a gas phase precursor; and

providing a plasma to the reaction space, thereby forming a viscous material in the recess,

wherein the viscous material flows in the recess and accumulates at a bottom of the recess, forming a deposit material at the bottom of the recess, an

Wherein the deposition material solidifies.

2. The method of claim 1, wherein the precursor is provided using a precursor flow in a range of about 10% to about 100% as part of a total gas flow to the reaction space.

3. The method of claim 1, wherein the partial pressure of the precursor in the reaction space is greater than 200 Pa.

4. The method of claim 1, wherein the temperature of the substrate is between about 50 ℃ to about 150 ℃.

5. The process of claim 1, wherein the total pressure within the reaction space is greater than 500 Pa.

6. The method of claim 1, wherein the precursor is polymerized using the plasma.

7. The method of claim 6, wherein the viscous material has an average chain length that is greater than ten times an average chain length of the precursor molecules.

8. The method of claim 1, wherein an amount of material deposited on the bottom is greater than an amount of material deposited on sidewalls of the recess.

9. The method of claim 1, wherein the precursor comprises an unsaturated hydrocarbon.

10. The method of claim 9, wherein the precursor comprises one or more of an unsaturated or cyclic hydrocarbon having a vapor pressure of 1,0000Pa or greater at 25 ℃.

11. The method of claim 1, wherein the precursor comprises one or more compounds selected from the group consisting of: C2-C8 alkyne (C)_nH_2n-2) C2-C8 olefins (C)_nH_2n) C2-C8 diene (C)_nH_n+2) C3-C8 cycloolefins, C3-C8 cycloolefins (C)_nH_n) C3-C8 cycloalkanes, and substituted hydrocarbons as described previously.

12. The method of claim 1, wherein the precursor comprises cyclopentene.

13. The method of claim 1, wherein the recesses have a width and a depth with an aspect ratio of about 2 to about 10.

14. The method of claim 1, wherein the viscous material is a liquid.

15. A method for filling a patterned recess of a substrate by: plasma-assisted deposition of a film with fill capability using a precursor in a reaction space, wherein a film without fill capability is capable of being deposited in the reaction space as a reference film on the substrate using the precursor when the precursor is supplied to the reaction space in a manner that provides a first partial pressure of the precursor on the patterned recesses of the substrate under first process conditions, the method comprising:

(i) supplying a silicon-free carbon-containing precursor to the reaction space in a manner that provides a second partial pressure of the precursor over the patterned recesses of the substrate under second process conditions, wherein the second partial pressure is higher than the first partial pressure to the extent that a filling capability is provided to the film when deposited under the second process conditions; and

(ii) exposing the patterned recesses of the substrate to a plasma under the second process conditions to deposit a silicon-free carbon-containing film having fill capability, wherein during a period of exposing the patterned recesses of the substrate to the plasma, a partial pressure of the silicon-free carbon-containing precursor is maintained higher than the first partial pressure to fill the recesses in a bottom-up manner,

wherein step (ii) is performed intermittently by pulsing the plasma, and step (i) is performed continuously or intermittently without overlapping step (ii), as a step prerequisite to step (ii).

16. The method of claim 15, wherein the silicon-free carbon-containing precursor is continuously supplied to the reaction space during steps (i) and (ii).

17. The method of claim 15, wherein the method comprises an atomic layer deposition work sequence.

18. The method of claim 15, wherein the silicon-free carbon-containing precursor comprises an unsaturated or cyclic hydrocarbon.

19. The method of claim 15, wherein the plasma-assisted deposition is a plasma-enhanced CVD deposition.

20. The method of claim 15, wherein the plasma-assisted deposition is plasma-enhanced ALD deposition.

Technical Field

The present invention generally relates to a method of depositing a silicon-free carbon-containing film as a gap fill layer in a trench by pulsed plasma assisted deposition.

Background

In a method of fabricating an integrated circuit, such as a shallow trench isolation, an inter-metal dielectric layer, a passivation layer, etc., it is often desirable to fill the trench (typically any recess having a high aspect ratio of 1 or more) with an insulating material. However, with the miniaturization of the wiring pitch of Large Scale Integration (LSI) devices, void-free filling of high aspect ratio spaces (e.g., AR ≧ 3) becomes increasingly difficult due to limitations of existing deposition processes.

Fig. 2 illustrates a schematic cross-sectional view of a trench subjected to a conventional plasma enhanced CVD process in the order of (a) and (b) to fill the gap. In a conventional plasma enhanced CVD process, a film grows faster on top of the trench 103 of the substrate 101 than inside the trench 103 because plasma reactions occur in the gas phase and reaction products accumulate on the substrate surface. Thus, when the layer 102 is deposited, the overhang portion 104 must be formed, as shown in (a). In addition, since deposition is performed layer by layer in the conventional CDV method, when the next layer 105 is deposited on the layer 102, the upper opening of the trench 103 is closed, leaving a void 106 inside the trench 103, as shown in (b).

Fig. 3 illustrates a schematic cross-sectional view of a trench subjected to a conventional gap filling process using an inhibitor in the order of (a), (b), and (c). By depositing the inhibitor 202 in the trench 201, which inhibits the reaction products from accumulating on the surface covered by the inhibitor, as shown in (b), the reaction products do not accumulate on the top surface and at the top of the trench 201 while accumulating at the bottom of the trench 201, achieving a bottom-up fill 203 as shown in (c). However, it is difficult to find a suitable combination of inhibitor and activator and to find suitable process conditions to perform the deposition. In many cases, this is not practical.

Fig. 4 illustrates a schematic cross-sectional view of a trench subjected to a conventional gap-filling process in the order of (a) and (b) using a highly anisotropic process. The highly anisotropic process is typically ion-driven deposition, in which plasma bombardment by a plasma containing ions causes plasma reactions of the deposited layer, anisotropically depositing layer 302 on the top surface and layer 303 inside trench 301 as a bottom-up fill, as shown in (b). However, as the trench is deeper, in order to bombard the bottom region of the trench with ions, the mean free path of the ions must be made longer to reach the bottom region, by, for example, significantly lowering the pressure to a high vacuum, which is often expensive and impractical.

Fig. 5 shows a schematic cross-sectional view of a trench in which a conventional gap filling process is performed in the order of (a) and (b) or (c) and (d) using a volume expansion process ((d) shows a loading effect). After depositing the layer on the surface of the substrate 405 with the trenches 401 as shown in (a) by, for example, an oxide layer 402, the layer may expand, increasing the volume or thickness of the layer and closing the gaps (trenches) 401 as shown in (b). However, as shown in (c), when the trench is composed of the narrow trench 401 and the wide trench 403, the wide trench has a significant opening 404 as shown in (d) even when the narrow trench is closed, due to a loading effect (i.e., a filling speed variation depending on a pattern density is referred to as a "loading effect"). In addition, as the layers expand and close the trench, the layers facing each other push against each other, thereby stressing the sidewalls of the trench as indicated by the arrows in (d), which often results in the structural portion of the trench or significantly collapsing.

Fig. 6 shows STEM photographs of cross-sectional views of trenches subjected to a conventional gap-filling process using a combination of deposition in (a), dry etching using different etchants in (b) to (d), and second deposition in (e) to (g) corresponding to (b) to (d), respectively. By combining deposition and etching, the topology or geometry of the gap-filled trench can be adjusted. However, as shown in FIG. 6, regardless of the type of etchant, CF in ((b) and (e)₄CHF in (c) and (f)₃And C in (d) and (g)₄F₈) The initial voids in the narrow trenches are not filled by etching and subsequent deposition. Further, as shown in fig. 6, a load effect is shown. In addition, this process is time consuming because at least the deposition is repeated and etching is performed in between.

Fig. 7 illustrates a schematic cross-sectional view of a trench subjected to a conventional gap-filling process using a flowable material in the order of (a) and (b). Since the liquid or viscous gas is flowable and naturally moves to the bottom of the trench, by using such liquid or viscous gas, the trench 502 formed in the substrate 501 can be filled with a flowable material, forming a bottom-up filler 503 as shown in (b). Typically, the temperature of the substrate is maintained at a low temperature, for example 50 ℃ or less, in order to keep the material flowable. This process is very fast and efficient. Although a loading effect is shown, it is not generally a problem because all trenches may be overfilled, followed by CMP. However, the materials are often of very poor quality and require an additional curing step. Furthermore, when the channel is narrow, the surface tension of the flowable material interferes with or even prevents the flowable material from entering the interior of the channel. Fig. 8 illustrates a schematic cross-sectional view of a trench for a conventional gap-fill process using a flowable material and illustrates the above-described problems. In this process, the flowable state of the precursor is achieved by polymerization in the reaction chamber, which polymerization takes place upon mixing with another precursor in the gas phase on the substrate, i.e. before reaching the substrate surface and/or immediately after contacting the top surface of the substrate. By polymerizing with other precursors in the gas phase, the precursors immediately change to a flowable state before reaching the substrate surface and/or at the moment of contact with the top surface of the substrate when their temperature is kept at a very low temperature. In any case, the flowable state is always achieved before entering the groove. Thus, as shown in fig. 8, the flowable material 504 does not enter the trench 502 of the substrate 501, and the top opening of the trench 502 is blocked by the mass 505 due to the surface tension of the flowable material 504 and prevents the flowable material 504 from entering the trench 502. In addition, the process always uses oxygen and nitrogen, sometimes hydrogen chemistry, and/or the precursor must have a very low vapor pressure in order to form a flowable state of the precursor.

In view of conventional gap-fill techniques, one embodiment of the present invention provides complete gap-fill by using plasma-assisted deposition of a hydrocarbon precursor without substantial void formation under conditions that do not require a nitrogen, oxygen, or hydrogen plasma. Embodiments may address one or more of the above-described problems.

Any discussion of problems and solutions related to the related art has been included in the present disclosure for the sole purpose of providing a context for the present invention, and should not be taken as an admission that any or all of the discussion is known at the time of filing the present application.

Disclosure of Invention

In some embodiments, it is an object of the present invention to provide silicon-free carbon-containing films with fill capability. In some embodiments, this may be achieved by: viscous polymers are formed by impinging an Ar or He plasma in a chamber filled with a volatile unsaturated or cyclic hydrocarbon precursor that can polymerize within certain parameter ranges that primarily define the partial pressure of the precursor during plasma impingement and the wafer temperature. The viscous phase flows at the bottom of the trench and fills the trench with a film having a bottom-up seamless capability. In some embodiments, this process may preferably be demonstrated using cyclopentene as a precursor; however, many other unsaturated or cyclic hydrocarbon compounds may be used alone or in any combination. In some embodiments, preferably, the process uses only a silicon-free hydrocarbon precursor and an inert gas to strike the plasma. In some embodiments, preferably, the process uses an ALD-like working procedure (e.g., feed/purge/plasma strike/purge) in which the purge after the feed is voluntarily severely shortened to retain a high partial pressure of the precursor during plasma strike. This is clearly distinguished from ALD chemistry or mechanism.

The above process may be based on pulsed plasma CVD, which also gives the resulting film good filling capability, but as discussed later, ALD-like working procedures may be more beneficial.

In some embodiments, key aspects of the flowability of the deposited film include:

1) a sufficiently high partial pressure during the entire RF-ON period for the polymerization/chain growth to progress;

2) energy sufficient to activate the reaction (defined by the RF-ON period and RF power), not for an excessive RF-ON period; and

3) set to a polymerization/chain growth temperature and pressure above the melting point of the flowable phase but below the boiling point of the deposition material.

For the purpose of summarizing aspects of the invention and the advantages achieved over the related art, certain objects and advantages of the invention are described in this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

Other aspects, features and advantages of the present invention will become apparent from the following detailed description.

Drawings

These and other features of the present invention will now be described with reference to the drawings of preferred embodiments, which are intended to illustrate and not to limit the invention. The figures are greatly simplified for illustrative purposes and are not necessarily to scale.

FIG. 1A is a schematic illustration of a PEALD (plasma enhanced atomic layer deposition) apparatus for depositing a dielectric film that may be used in one embodiment of the invention.

FIG. 1B illustrates a schematic diagram of a precursor supply system using a flow-through system (FPS) that may be used with embodiments of the present invention.

Fig. 2 illustrates a schematic cross-sectional view of a trench subjected to a conventional CVD process in the order of (a) and (b) to fill the gap.

Fig. 3 illustrates a schematic cross-sectional view of a trench subjected to a conventional gap filling process using an inhibitor in the order of (a), (b), and (c).

Fig. 4 illustrates a schematic cross-sectional view of a trench subjected to a conventional gap-filling process in the order of (a) and (b) using a highly anisotropic process.

Fig. 5 illustrates a schematic cross-sectional view of a trench in which a conventional gap filling process is performed in the order of (a) and (b) or (c) and (d) using a volume expansion process ((d) shows a loading effect).

Fig. 6 shows STEM photographs of cross-sectional views of trenches subjected to a conventional gap-filling process using a combination of deposition in (a), dry etching using different etchants in (b) to (d), and second deposition in (e) to (g) corresponding to (b) to (d), respectively.

Fig. 7 illustrates a schematic cross-sectional view of a trench subjected to a conventional gap-filling process using a flowable material in the order of (a) and (b).

Fig. 8 illustrates a schematic cross-sectional view of a trench for a conventional gap-fill process using a flowable material.

Fig. 9 illustrates a schematic cross-sectional view of a trench with a gap-filling process performed in order of (a), (b), and (c) according to an embodiment of the present invention.

Fig. 10 shows STEM photographs of cross-sectional views of a deep trench (in (a)) subjected to a gap-fill cycle that is repeated 240 times and a trench (in (b)) having a different opening size (width) subjected to a gap-fill cycle that is repeated 240 times, in accordance with an embodiment of the present invention.

Fig. 11 shows STEM photographs of cross-sectional views of a wide trench (in (a)) subjected to a gap-filling cycle, wide and narrow trenches (in (b)) subjected to a gap-filling cycle, and a narrow trench (in (c)) subjected to a gap-filling cycle, according to a comparative example.

FIG. 12 shows a flowchart indicating the use of data analysis software according to an embodiment of the present invention

A diagram of a schematic relationship between the obtained process parameter and the flowability is obtained.

Fig. 13 to 28 show STEM photographs of cross-sectional views of trenches deposited by a PEALD-like working procedure with gap-filling, where fig. 27 shows a B/T ratio of 3.0 or higher, fig. 28 shows a B/T ratio of 2.5 or higher but less than 3.0, fig. 13 and 24 show a B/T ratio of 2.0 or higher but less than 2.5, fig. 14, 15, 16 and 25 show a B/T ratio of 1.5 or higher but less than 2.0, and fig. 17 to 23 and 26 show a B/T ratio of less than 1.5 (comparative examples).

Detailed Description

In the present disclosure, "gas" may comprise vaporized solids and/or liquids, and may consist of a single gas or a mixture of gases, depending on the context. Also, depending on the context, the article "a" refers to one species or a genus comprising a plurality of species. In the present disclosure, the process gas introduced into the reaction chamber through the showerhead may comprise, consist essentially of, or consist of the silicon-free hydrocarbon precursor and the additive gas. The additive gas may comprise a plasma generating gas for exciting the precursor to deposit amorphous carbon when RF power is applied to the additive gas. The additive gas may be an inert gas, which may be fed to the reaction chamber as a carrier gas and/or a diluent gas. The additive gas may be free of reactive gases for oxidizing or nitriding the precursor. Alternatively, the additive gas may contain a reactive gas for oxidizing or nitriding the precursor to the extent that it does not interfere with the plasma polymerization to form the amorphous carbon-based polymer. Further, in some embodiments, the additive gas contains only inert gas. The precursor and additive gases may be introduced into the reaction space as a mixed gas or separately. The precursor may be introduced using a carrier gas such as a noble gas. Gases other than process gases, i.e. gases introduced without passing through the showerhead, may be used, for example, to seal the reaction space, which contains a sealing gas such as a noble gas. In some embodiments, the term "precursor" generally refers to a compound that participates in a chemical reaction that produces another compound, and particularly refers to a compound that constitutes the membrane matrix or the main framework of the membrane, while the term "reactant" refers to a compound that is not an activated precursor of a precursor, modifies a precursor, or catalyzes a reaction of a precursor, wherein the reactant can provide an element (e.g., N, C) to and become part of the membrane matrix when RF power is applied. The term "inert gas" refers to a plasma-generating gas that excites the precursor when RF power is applied, but which, unlike the reactants, does not become part of the film-forming substrate.

In some embodiments, a "film" refers to a substantially non-porous layer that extends continuously in a direction perpendicular to the thickness direction to cover the entire target or associated surface, or simply refers to a layer that covers the target or associated surface. In some embodiments, "layer" refers to a structure formed on a surface having a certain thickness, or synonym for a film or non-film structure. A film or layer may be comprised of a discrete single film or layer or of multiple films or layers having certain characteristics, and the boundaries between adjacent films or layers may or may not be transparent and may be established based on physical, chemical, and/or any other characteristics, forming processes or sequences, and/or the function or purpose of the adjacent films or layers. Further, in the present disclosure, since the operable range may be determined based on conventional work, any two numbers of a variable may constitute the operable range of the variable, and any range indicated may include or exclude endpoints. Additionally, any values for the indicated variables (whether they are indicated with "about" or not) can refer to exact or approximate values and include equivalents and, in some embodiments, can refer to mean, median, representative, majority, and the like. Further, in this disclosure, in some embodiments, the terms "consisting of … …" and "having" independently mean "typically or broadly comprising," including, "" consisting essentially of … …, "or" consisting of … …. In the present disclosure, in some embodiments, any defined meaning does not necessarily exclude a common and customary meaning.

In the present disclosure, "continuous" means, in some embodiments, without interrupting the vacuum, without interrupting as a timeline, without any material insertion steps, without changing processing conditions, immediately thereafter, as a next step, or without inserting a discrete physical or chemical structure between two structures that are not two structures.

In the present disclosure, the term "fill ability" refers to the ability to fill a gap substantially free of voids (e.g., voids having a dimension of about 5nm or greater in diameter) and seams (e.g., no seams having a length of about 5nm or greater), wherein a seamless/void-free growth of the layer is observed from bottom to top, said growth at the bottom of the gap being at least about 1.5 times faster than growth on the sidewalls of the gap and on the top surface with the gap. Films with filling capability are also referred to as "flowable films" or "tacky films". The flowable or viscous behavior of the film is typically manifested as a concave surface at the bottom of the trench. For example, fig. 13 shows STEM photographs of cross-sectional views of trenches having different opening sizes (widths) subjected to a gap-fill cycle, in accordance with an embodiment of the present invention. As shown in fig. 13, the flowable film showed growth at the bottom of the trench that was at least about 1.5 times faster than growth on the sidewalls and on the top surface of the trench. In contrast, for example, fig. 23 shows STEM photographs of cross-sectional views of trenches with different opening sizes (widths), where films without fill capability were deposited (using the same precursors as in fig. 13). As shown in fig. 23, the non-flowable film showed growth at the bottom of the trench, which was approximately the same as growth on the top surface, and did not show a substantially concave surface at the bottom.

The flowability can be determined as follows:

TABLE 1

Bottom/top ratio (B/T)	Fluidity of the resin
		0<B/T<1	Is free of
1≤B/T<1.5	Not good at
		1.5≤B/T<2.5	Good effect
2.5≤B/T<3.5	Is very good
		3.5≤B/T	Is excellent in

B/T refers to the ratio of the thickness of the film deposited at the bottom of the trench to the thickness of the film deposited on the top surface where the trench is formed before the trench is filled. Generally, the fluidity is evaluated using wide trenches having an aspect ratio of about 1 or less, because in general, the higher the aspect ratio of the trenches, the higher the B/T ratio becomes. For example, fig. 11 shows STEM photographs of cross-sectional views of a medium and wide trench (in (a)) subjected to a gap-fill cycle, a medium and narrow trench (in (b)) subjected to a gap-fill cycle, and a narrow trench (in (c)) subjected to a gap-fill cycle, wherein the narrow, medium and wide trenches have the dimensions shown in table 2 below. Since the B/T ratio becomes high when the aspect ratio of the trench is high as shown in fig. 11, the fluidity when the film is deposited in a wide trench having an aspect ratio of about 1 or less is generally evaluated.

Table 2 (values are approximations)

	Opening [ nm ]]	Depth [ nm ]]	AR (aspect ratio)
				Narrow and narrow	30	90	3
Medium and high grade	70	90	1.3
				Width of	100	90	0.9

In the above, once the trench is filled, the "growth" rate, defined by the thickness, decreases; however, since this is a flowable process, volume growth should be considered. Usually, per nm³The growth of (b) is constant throughout the deposition step, although the narrower the trench, the faster the growth in the Z (vertical) direction becomes. Furthermore, since the precursor flows to the bottom of the recesses, once all trenches, holes or other recesses are filled, growth proceeds in a classical manner by a planarization effect, regardless of geometry, forming a substantially planar surface as shown in fig. 10. Fig. 10 shows STEM photographs of cross-sectional views of a deep trench (in (a)) subjected to a gap-fill cycle repeated 242 times and a trench (in (b)) having a different opening size (width) subjected to a gap-fill cycle repeated 242 times, in accordance with an embodiment of the present invention. In some embodiments, the growth rate of the flowable film in the conventional sense is in the range of 0.01 to 10nm per cycle on a planar surface (in the form of blanket deposition).

In the present disclosure, the recesses between adjacent protrusion structures and any other recess pattern are referred to as "grooves". That is, the trench is any recess pattern that includes holes/vias, and which in some embodiments has a width of about 20nm to about 100nm (typically about 30nm to about 50nm) (where when the trench has substantially the same length as the width, it is referred to as a hole/via, and has a diameter of about 20nm to about 100nm), a depth of about 30nm to about 100nm (typically about 40nm to about 60nm), and an aspect ratio of about 2 to about 10 (typically about 2 to about 5). The appropriate dimensions of the trenches may vary depending on process conditions, film composition, intended application, and the like.

When a volatile hydrocarbon precursor is polymerized and deposited on the substrate surface, for example by plasma, the flowability of the film is temporarily obtained, wherein the gaseous monomer (precursor) is activated or fragmented by the energy provided by the plasma gas discharge in order to initiate the polymerization, and when the resulting polymeric material is deposited on the substrate surface, the material shows a temporarily flowable behavior. When the deposition step is completed, the flowable film is no longer flowable but rather solidified, and thus a separate solidification process is not required.

Since in general plasma chemistry is very complex and the precise nature of the plasma reaction is difficult to characterize and largely unknown, it is difficult to elucidate the reaction formula when polymerizing hydrocarbons.

Deposition of flowable films is known in the art; however, conventional deposition of flowable films uses Chemical Vapor Deposition (CVD) with constant applied RF power, since pulsed plasma assisted deposition (such as PEALD) is well known for depositing conformal films, which are films with characteristics that are diametrically opposite to those of flowable films. In some embodiments, the flowable film is a silicon-free carbon-containing film composed of an amorphous carbon polymer, and although any suitable hydrocarbon precursor or precursors may be candidates, in some embodiments the precursors comprise unsaturated or cyclic hydrocarbons having a vapor pressure of 1,000Pa or greater at 25 ℃. In some embodiments, the precursor is at least one selected from the group consisting of: C2-C8 alkyne (C)_nH_2n-2) C2-C8 olefins (C)_nH_2n) C2-C8 diene (C)_nH_n+2) C3-C8 cycloolefins, C3-C8 cycloolefins (C)_nH_n) C3-C8 cycloalkanes, and substituted hydrocarbons as described previously. In some embodiments, the precursor is ethylene, acetylene, propylene, butadiene, pentene, cyclopentene, benzene, styrene, toluene, cyclohexene, and/or cyclohexane.

If halide, N or O contamination is not desired in the film, then preferably the precursor does not have such elements in its functional groups. However, if that is not a problem, hydrocarbon compounds having amine, alcohol, acid functional groups, etc. may be used as precursors.

Saturated hydrocarbon compounds are generally not preferred; however, it may be usable as long as it is polymerized by plasma activation at a high partial pressure.

For liquids, the vapor pressure is preferably above 1,000Pa, most preferably above 10,000Pa at 25 ℃. For example, cyclopentene has a vapor pressure of 53,000Pa at 25 ℃.

In some embodiments, the volatile hydrocarbon precursor polymerizes over a range of parameters defined primarily by the precursor partial pressure during plasma strike, the wafer temperature, and the pressure in the reaction chamber. To adjust the "precursor partial pressure," indirect process knobs (dilution gas flow) are typically used to control the precursor partial pressure. Controlling the fluidity of the deposited film does not require the absolute number of partial pressures of the precursor, and instead, the ratio of the flow rate of the precursor to the flow rate of the remaining gas and the total pressure in the reaction space at the reference temperature may be used as actual control parameters. If the precursor is extremely dilute, chain growth stops before it can exhibit rich liquid-like behavior, or polymerization does not occur at all as with standard plasma CVD deposition. If the precursor gas ratio (the ratio of precursor flow rate to total gas flow rate) is low during the entire plasma strike period, no or very little bottom-up fill is observed, assuming constant total pressure and temperature (unless otherwise stated, this assumption applies when discussing precursor gas ratios). At low precursor gas ratios, polymerization can occur to some extent, but the supply is too low to form polymer chains long enough to have liquid-like behavior. In some embodiments, the precursor gas ratio is in the range of about 10% to about 100%, preferably about 50% to about 90%.

In some embodiments, such parameter ranges are adjusted as follows:

table 3 (values are approximations)

High pressure is preferred for fluidity in terms of pressure, since gravity is the driving force for the membrane to flow at the bottom. In terms of temperature, low temperatures are preferred for fluidity (which is much less intuitive), although high temperatures favor polymer chain growth rates. For example, the phase change between the gas precursor and solidification may be as follows:

TABLE 4

Chain length	x	5x	10x
				Status of state	Gas (es)	Liquid, method for producing the same and use thereof	Solid body

Alternatively or additionally, solidification may occur upon contact with the substrate, wherein this reaction is thermally activated. A high precursor gas ratio is preferred for flowability in terms of precursor gas ratio, since at low precursor partial pressures, although polymerization can occur, the supply is too low to form polymer chains long enough to have liquid-like behavior. In terms of RF-on time, there is an optimum value of RF-on time above or below which the ability to flow to the bottom is diminished (the optimum value depends on other process parameters). It should be noted that changing these process parameters significantly changes the bottom-up growth process window. For example, when the fluidity of the deposited film is observed at 50 ℃ and 500Pa pressure, the pressure needs to be changed to at least 700Pa at 75 ℃ while keeping all other parameters constant. The same is true for pressure, temperature and precursor gas ratio.

FIG. 12 shows a flowchart indicating the use of data analysis software according to an embodiment of the present invention (PEALD-like process)

A diagram of a schematic relationship between the obtained process parameter and the flowability is obtained. The upper vertical axis ("top/bottom") refers to (top thickness in isolation region)/(bottom of isolation region)Section thickness) that is the inverse of the ratio of B/T, wherein a ratio of 1 indicates that the deposited film has no flowability, and a ratio of 0 indicates that the deposited film has full or complete flowability. The lower vertical axis ("desirability") refers to the degree of desirable flowability on a scale of 0 to 1, where 1 indicates that the flowability is completely satisfactory and 0 indicates that the flowability is not completely satisfactory. The graph is using data analysis software

Obtained, it can be based on available experimental data through modeling and statistical analysis to determine the effect of each process parameter on flow. This software allows such information without complete data at each parameter set point (e.g., complete data at each pressure, each temperature, etc., and combinations thereof, would not be needed to obtain the effect of clearance on flow). For example, the middle graph shows the relationship between pressure (total pressure) and T/B ratio, which indicates that a pressure of 1100Pa is most desirable in this data set. Also, the graph shows that a flow of He of 0.5slm, a gap of 16mm, and a temperature of 50 deg.C are most desirable.

Flowable films can be deposited not only by Plasma Enhanced Atomic Layer Deposition (PEALD), but also by Plasma Enhanced Chemical Vapor Deposition (PECVD) using pulsed plasmas. However, in general, PECVD with pulsed feeding (on-off pulsing) is not preferred, because the precursor partial pressure becomes too low when the precursor is not fed to the reaction space while RF power is applied to the reaction space. The partial pressure of the precursor at the reference temperature used to deposit the flowable film should be greater than the partial pressure of the precursor to deposit the non-flowable film because a relatively high molar concentration of the precursor at the reference temperature is required when RF power is applied to cause plasma polymerization to render the deposited film flowable, see the conditions employed when plasma reaction products are continuously formed in the vapor phase by PECVD and continuously deposited on the substrate with voids formed in the trenches as shown in fig. 2, or when plasma reaction products are formed on the surface by surface reaction by PEALD only (where bottom-up structures cannot be formed in the trenches). In some embodiments, in PEALD, by shortening the purge duration, the precursor on the top surface may be removed primarily while the precursor in the trench may remain in the trench and, when the precursor is exposed to the plasma, a more viscous polymer forms in the trench than on the top surface and the viscous polymer also flows to the bottom of the trench, forming a layer with a concave surface at the bottom. As discussed above, in PEALD, by performing the purge after the precursor feed in a significantly insufficient amount or significantly shortening the purge, the molar concentration of the precursor in the trench can be kept relatively high at the reference temperature when the RF power is applied to the reaction space. In some embodiments, the purge after precursor feed is shortened such that the partial pressure of the precursor at the reference temperature in the trench after the shortened purge can be considered to be substantially the same as the partial pressure of the precursor at the reference temperature when the precursor is fed to the reaction space. It should be noted that the above process is significantly different from conventional PEALD; however, for convenience, in the present disclosure, the above process may be referred to as a PEALD-like process or simply PEALD, where PEALD refers to a process using equipment for PEALD.

In some embodiments, depending on the chamber volume, the distance between the upper and lower electrodes, the feed time, the purge time, the total gas flow, the precursor vapor pressure (the amount of which also depends on the ambient temperature and the amount of precursor remaining in the bottle, etc.), etc., the purge duration (in seconds) after the precursor feed in an ALD cycle is 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, and a range between any two of the foregoing values, which can be determined by one skilled in the art through routine experimentation based on the entirety of the present disclosure. In some embodiments, also depending on the factors described above, the precursor flow rate (sccm) is 50, 100, 150, 200, 300, 400, 500, 600, 700, and a range between any two of the foregoing values, in both a PEALD-like process and PECVD using continuous or pulsed plasma. In some embodiments, also depending on the factors described above, in a PEALD-like process, the duration (in seconds) of the precursor feed in an ALD cycle is 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, and a range between any two of the foregoing values. In some embodiments, the duration (in seconds) of the RF power application is 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, and ranges between any two of the foregoing values, depending on the factors described above. In some embodiments, the purge duration (in seconds) after the RF power application is 0.0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, and ranges between any two of the foregoing values, depending on the factors described above.

Fig. 9 illustrates the PEALD-like process discussed above, showing a schematic cross-sectional view of a trench with a gap-fill process performed in the order of (a), (b), and (c), in accordance with an embodiment of the invention. The substrate 31 having the trench 32 is placed in the reaction space in (a), and a precursor is fed to the reaction space, so that the trench 32 is filled with the gas-phase precursor 33 in (b). Thereafter, the gas phase precursor is exposed to a plasma strike, forming a viscous phase in the trench 32 directly (not before reaching the trench (as in standard PECVD) nor after reaching the trench (as in standard PEALD)), which deposits in the trench 32 and also flows into the trench 32, wherein viscous species (polymers) 36 accumulate at the bottom of the trench 32 (the surface is schematically indicated as a planar surface for illustrative purposes), although very little deposition 35 is observed on the sidewalls, and only a thin layer 34 is deposited on the top surface in (c). The plasma polymerization process does not require nitrogen, oxygen, or hydrogen as reactants or chamber pressure limitations.

Although flowable films can be deposited not only by PEALD-like processes, but also by PECVD using a constant plasma or pulsed plasma, it may be beneficial to use PEALD-like processes. For example, it is beneficial when the precursor changes from the gas phase to the liquid phase intermittently during deposition, as the constant liquid phase will be more likely to have surface tension problems (which are highly structure dependent, and the narrower the trench, the worse the problem becomes), as shown in fig. 8. In addition, PECVD using pulsed plasma consumes significantly more precursor than PEALD-like processes.

As mentioned above, in order to achieve the flowability of the precursor, the partial pressure of the precursor at a reference temperature in the reaction space is one of the important parameters, since the molar concentration of the precursor can be expressed as follows:

n/V as p/RT (ideal gas law)

Wherein T: thermodynamic temperature, P: pressure, n: amount of substance, V: volume and R: gas constant.

Thus, if the deposition temperature becomes higher, the deposition precursor partial pressure also becomes higher to maintain the same molar concentration. If the temperature is constant, the molar concentration of the precursor corresponds directly to the partial pressure of the precursor, which can be treated as a control parameter of the process. In addition, if the period of RF power application is extended in a PEALD-like process, the molar concentration of the precursor in the trench decreases towards the end of the period, resulting in insufficient amounts of precursor molecules in the trench upon exposure to the plasma, resulting in deposition of less flowable or difficult to flow material, or curing of deposited flowable material, or stopping the flowability of the material. If the period of RF power application is too short, on the other hand, sufficient plasma polymerization cannot occur and thus a flowable film does not form or deposit in the trench. In some embodiments, the period of RF power application (period of exposure to plasma) may be in the range of about 0.7 seconds to about 2.0 seconds (preferably about 1.0 second to about 2.0 seconds), which is applicable to both PEALD-like processes and PECVD using pulsed plasma. The plasma exposure time can also be adjusted by varying the distance between the upper and lower electrodes (conductively coupled parallel electrodes), wherein by increasing the distance, the holding time for the precursor to remain in the reaction space between the upper and lower electrodes can be extended when the flow rate of the precursor into the reaction space is constant. In some embodiments, the distance (mm) between the upper electrode and the lower electrode is 5, 10, 15, 20, 25, 30, and a range between any two of the foregoing values. In some embodiments, the RF power (W) (e.g., 13.56MHz) for flowable film deposition is 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 10000, and a range between any two of the foregoing values, as measured for 300mm wafers, which can be measured for different size wafers in both PEALD-like processes and PECVD using pulsed plasmaConversion to W/cm²The unit of (c).

In the present disclosure where no conditions and/or structures are specified, such conditions and/or structures can be readily provided by one skilled in the art in light of the present disclosure, following routine experimentation.

In all disclosed embodiments, any element used in one embodiment may be substituted for any element equivalent thereto, including those explicitly, necessarily, or inherently disclosed herein, for the intended purpose. Furthermore, the present invention is equally applicable to apparatus and methods.

Embodiments will be described with reference to preferred embodiments. However, the invention is not limited to the preferred embodiments.

Some embodiments provide a method for filling patterned recesses of a substrate by pulsed plasma-assisted deposition of a silicon-free carbon-containing film with fill capability using a hydrocarbon precursor in a reaction space, wherein the silicon-free carbon-containing film with no fill capability can be deposited as a reference film on the substrate using the hydrocarbon precursor in the reaction space when the hydrocarbon precursor is supplied to the reaction space in a manner that provides a first partial pressure of the precursor over the patterned recesses of the substrate under first process conditions, the method comprising: (i) supplying a hydrocarbon precursor to the reaction space in a manner that provides a second partial pressure of the precursor over the patterned recesses of the substrate under second process conditions, wherein the second partial pressure is higher than the first partial pressure to the extent that a filling capability is provided to the silicon-free carbon-containing film when deposited under the second process conditions; and (ii) exposing the patterned recesses of the substrate to a plasma under second process conditions to deposit a silicon-free carbon-containing film having filling capability, wherein during the entire period of exposing the patterned recesses of the substrate to the plasma, the partial pressure of the precursor is maintained higher than the first partial pressure to fill the recesses in a bottom-up manner, wherein step (ii) is intermittently performed in a pulsed plasma manner, and step (i) is performed continuously or intermittently without overlapping step (ii), as a step prerequisite of step (ii).

In some embodiments, the pulsed plasma assisted deposition is a pulsed plasma enhanced CVD deposition in which the precursor is supplied to the reaction space continuously throughout steps (i) and (ii), i.e. step (ii) is performed intermittently in the form of a pulsed plasma, while step (i) is performed continuously.

In some embodiments, the pulsed plasma assisted deposition is a plasma enhanced ALD-like deposition following a plasma enhanced ALD deposition work sequence layout consisting of repeated deposition cycles, each cycle comprising step (i) in which the precursor is supplied in pulses, and step (ii) in which RF power is applied in pulses without overlapping with the precursor pulses, i.e., step (ii) is performed intermittently in the form of pulsed plasma, and step (i) is performed intermittently without overlapping with step (ii), as a step prerequisite of step (ii).

In some embodiments, each cycle of PEALD-like deposition comprises step (i) followed by a purge, and step (ii), wherein after step (ii), no purge is performed in each cycle, wherein the duration of the purge is less than half the duration of step (i), and the duration of step (ii) is more than twice the duration of step (i).

In some embodiments, the second process conditions comprise a flow rate of plasma ignition gas of 0.8slm or less, a pressure of 900Pa or more, and a temperature of 85 ℃ or more.

In some embodiments, the gas supplied to the reaction space throughout steps (i) and (ii) is: a precursor; optionally a carrier gas which is N₂Ar and/or He; and a plasma ignition gas of Ar, He or N₂Or mixtures of the foregoing, wherein the plasma ignition gas contains hydrogen in the range of 0% to 30%. In some embodiments, a carrier gas is used and is He, N₂Or Ar, and the plasma ignition gas is He or N₂Or Ar. In some embodiments, also depending on the factors described above, the flow rates (slm) of these optional dry gases are 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, and ranges between any two of the foregoing values in both PEALD-like processes and PECVD using pulsed plasma. In some embodiments of the present invention, the,ar or He plasma is used for polymerization without the need for H; however, the addition of H (e.g., about 1% to about 30% relative to the total dry gas flow) is not detrimental to the filling characteristics. In addition, O is added₂Ar or N₂(e.g., about 1% to about 30% relative to the total dry gas flow) is not detrimental to the fill characteristics.

In some embodiments, the first process conditions comprise a first process temperature, a first process pressure, a first flow rate of the precursor, a first flow rate of the carrier gas, and a first flow rate of the plasma ignition gas, wherein in step (ii), the second process conditions are set without changing the first flow rate of the precursor by reducing the first process temperature to a second process temperature, increasing the first process pressure to a second process pressure, and/or reducing the first flow rate of the plasma ignition gas.

In some embodiments, steps (i) and (ii) continue until the patterned recesses are completely filled with the film having fill capability, with substantially no voids (which can be observed in STEM photographs of cross-sectional views of trenches as free spaces having dimensions of about 5nm or greater) being formed in the filled recesses.

In some embodiments, steps (i) and (ii) stop when the film with fill capability is deposited on the bottom and sidewalls of the patterned recess in a shape such that a cross-section of the deposited film in the recess has a top surface with a downwardly parabolic shape, wherein a thickness of the deposited film in the recess at the center of the bottom of the recess is at least twice a thickness of the deposited film on the top surface of the substrate, and substantially no void is formed in the filled recess.

In some embodiments, the method further comprises exposing the substrate to an Ar or He plasma as a post-deposition treatment after completing the deposition of the film with fill capability. The periodic H (or O) plasma treatment may be applied with benefits in terms of shrinkage, RI, dry etch rate characteristics, and O content after annealing (e.g., at 450 ℃ for 30 minutes in a nitrogen atmosphere). H₂The effect of the treatment is to form a higher crosslinking order of the polymer, thereby stabilizing the polymer structure and properties. On the other hand, O₂The only effect of the treatment is the oxidation of the carbon polymer. In some embodiments of performing a PEALD-like process, the RF power (W) at which the periodic plasma treatment is performed may be 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 10000, and ranges between any two of the foregoing values, as measured for 300mm wafers, which may be converted to W/cm for wafers of different sizes²Is 1, 5, 10, 20, 30, 40, 50, 60, and ranges between any two of the foregoing values, and an ALD-like cycle/process ratio is 1/1, 2/1, 3/1, 4/1, 5/1, 6/1, 7/1, 8/1, 9/1, 10/1, 20/1, 30/1, 40/1, 50/1.

In some embodiments, the second process conditions comprise a second process pressure and a second process temperature, wherein the second process temperature is above the melting point of the silicon-free carbon-containing film with fill capability but below its boiling point at the second partial pressure.