Impurity reduction in silicon-containing films

Abstract

The various embodiments described herein relate to methods and apparatus for depositing doped or undoped silicon-containing films of high purity. In one example, the method includes exposing a substrate to a first reactant and a second reactant; reacting the first and second reactants with each other to form a silicon-containing material; depositing a portion of the silicon-containing film on the substrate; performing an impurity reduction operation prior to the completion of the silicon-containing film, wherein the impurity reduction operation includes: (i) generating a plasma from a plasma-generating gas comprising an inert gas and hydrogen, wherein the plasma-generating gas is substantially oxygen-free; and (ii) exposing the substrate to the plasma to reduce the concentration of fluorine, carbon, hydrogen, and / or nitrogen in the silicon-containing film; and repeating these operations (or a subset thereof) until the silicon-containing film is deposited to a final thickness.

Description

Technical Field

[0001] This application relates to the reduction of impurities in silicon-containing films. Prior Technology

[0002] The fabrication of semiconductor devices involves many different processes, including, for example, deposition and etching. One of the commonly used materials for deposition is silicon oxide.

[0003] The prior art description provided herein is for the purpose of generally presenting the background of this disclosure. The work of the inventors listed in this case, the scope of the prior art paragraphs herein, and the embodiments that may not have been qualified as prior art at the time of application are not intended or implied as prior art against the content of this disclosure. Summary of the Invention

[0004] One embodiment relates to a method for depositing a doped or undoped silicon-containing film on a substrate, the method comprising: (a) exposing the substrate to a first reactant, wherein the first reactant is a silicon-containing reactant; (b) reacting at least the first reactant in a first plasma to form a doped or undoped silicon-containing material, and depositing a portion of the doped or undoped silicon-containing film having a first impurity concentration on the substrate; (c) performing an impurity reduction operation prior to completion of deposition of the portion of the doped or undoped silicon-containing film, wherein the impurity reduction operation comprises: (i) generating a second plasma from a plasma-generating gas, wherein the plasma-generating gas comprises an inert gas and hydrogen (H2), and wherein the plasma-generating gas is substantially oxygen-free (O2); and (ii) exposing the substrate to the second plasma to reduce the first impurity concentration in the doped or undoped silicon-containing film to a second impurity concentration; and (d) Repeat at least one of (a) and (b) or (c) until the doped or undoped silicon-containing film is deposited to the final thickness.

[0005] In various embodiments, the impurity is one or more of fluorine, carbon, hydrogen, nitrogen, and combinations thereof.

[0006] In various embodiments, the second reactant is an oxygen-containing reactant.

[0007] In some embodiments, the first reactant and the second reactant are simultaneously directed into a chamber including the substrate. In some embodiments, the first reactant and the second reactant are directed into a chamber including the substrate by temporarily spaced pulses.

[0008] In various embodiments, the method further includes (e) exposing the substrate to a second reactant, such that reacting the at least the first reactant includes reacting the first reactant with the second reactant to form the doped or undoped silicon-containing material, such that repeating at least one of (a) and (b) or (c) further includes repeating (e).

[0009] In various embodiments, the doped or undoped silicon-containing film is deposited in a plurality of recessed features formed on the surface of the substrate. The method further includes exposing the substrate to etching chemicals to etch the top of the doped or undoped silicon-containing film in the recessed features before the doped or undoped silicon-containing film completely fills the recessed features.

[0010] In various embodiments, the doped or undoped silicon-containing film system is deposited in a plurality of recessed features formed on the surface of the substrate. The method further includes exposing the substrate to inhibitory chemicals to selectively inhibit deposition near the top of the recessed features rather than at the bottom and middle of the recessed features.

[0011] In some embodiments, the concentration of the second impurity is 10 times smaller than the concentration of the first impurity.

[0012] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the fluorine concentration in the doped or undoped silicon-containing film is on the order of approximately 1E16 atoms / cc.

[0013] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is approximately 1E20 atoms / cc or less.

[0014] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is approximately 5E19 atoms / cc or less.

[0015] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is about 2% or less (atomic percentage). For example, in some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is about 0.5% or less (atomic percentage).

[0016] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is approximately 5E20 atoms / cc or less. For example, in some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is approximately 1.5E20 atoms / cc or less.

[0017] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is about 5% or less (atomic percentage). For example, in some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is about 0.75% or less (atomic percentage).

[0018] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the nitrogen concentration in the doped or undoped silicon-containing film is approximately 3E20 atoms / cc or less.

[0019] In some embodiments, after the doped or undoped silicon-containing film reaches the final thickness, the nitrogen concentration in the doped or undoped silicon-containing film is about 1.5% or less (atomic percentage).

[0020] In some embodiments, generating the plasma system in (d)(i) includes flowing the inert gas at a rate of about 2 slm to about 60 slm, flowing the hydrogen at a rate of about 0.5 slm to about 5 slm, and generating the plasma at an RF power level, wherein the RF power level includes HF RF of about 1000 W to about 5000 W and LF RF of about 0 W to about 2000 W.

[0021] In some embodiments, the substrate is exposed to the plasma system for less than about 1 second in (d)(ii).

[0022] In some embodiments, the inert gas in the plasma generating gas includes argon.

[0023] In some embodiments, the plasma-generating gas includes nitrogen (N2).

[0024] In some embodiments, the first reactant comprises silane. In some embodiments, the first reactant comprises aminosilane.

[0025] Another embodiment relates to an apparatus for depositing doped or undoped silicon-containing films on a substrate, the apparatus comprising: a processing chamber; an inlet for directing reactants into the processing chamber; a plasma generator for generating plasma in the processing chamber; and a controller configured to perform any of the methods described herein.

[0026] These and other states will be further described below with reference to the diagram. Simple Explanation of the Diagram

[0027] Figure 1A illustrates the process flow for depositing silicon oxide films via atomic layer deposition, where impurity reduction is included as part of the atomic layer deposition cycle.

[0028] Figure 1B illustrates the process flow for depositing silicon oxide films via atomic layer deposition, where impurity reduction is performed periodically after multiple atomic layer deposition cycles.

[0029] Figure 1C illustrates the process flow for depositing silicon oxide films using a suppression-based deposition scheme, where impurity reduction is performed periodically throughout the deposition process of the silicon oxide film.

[0030] Figure 1D illustrates the process flow for depositing silicon oxide films using a deposition-etch-deposition scheme, where impurity reduction is performed periodically throughout the deposition process of the silicon oxide film.

[0031] Figure 1E illustrates the process flow for depositing silicon oxide films via chemical vapor deposition, where impurity reduction is performed periodically throughout the deposition process of the silicon oxide film.

[0032] Figure 2 shows an exemplary processing station that can be used to implement the methods described herein.

[0033] Figure 3 shows an exemplary multi-station processing tool that can be used to implement the methods described herein.

[0034] Figures 4A-4C illustrate experimental results related to the concentration of different impurities, where the silicon oxide film system was deposited using certain methods.

[0035] Figures 5A and 5B illustrate the experimental results related to the concentration of different impurities, in which the silicon oxide film system was deposited under conditions of no periodic impurity reduction (Figure 5A) and with a periodic impurity reduction step (Figure 5B).

[0036] Figure 6 shows the various impurity concentrations (atomic percentages) compared to the impurity reduction treatment with the impurity reduction treatment.

[0037] Figures 7A and 7B show the experimental data from FTIR, which suggest that the impurity reduction described in this paper resulted in a decrease in the hydrogen-related peak (Figure 7A) and an increase in the silicon-oxygen-related peak (Figure 7B). Implementation

[0038] In the following description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, conventional processing operations have not been described in detail to avoid unnecessarily obscuring the disclosed embodiments. While the disclosed embodiments will be described in conjunction with specific embodiments, it will be understood that these specific embodiments are not intended to limit the disclosed embodiments.

[0039] Silicon-containing materials are frequently deposited during the fabrication of semiconductor devices. Exemplary silicon-containing materials include silicon oxides, silicon oxides, silicon nitrides, silicon carbonitrides, silicon carbon oxides, and silicon hydrides. Silicon-containing materials can be doped or undoped. Doped materials include dopants such as boron and / or phosphorus. Several different deposition processes are possible. In many cases, vapor-based deposition processes are used. Exemplary vapor-based deposition processes include, for example, atomic layer deposition (ALD), plasma-enhanced atomic layer deposition (PEALD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), remote plasma chemical vapor deposition (RPCVD), remote plasma atomic layer deposition (RPALD), inductively coupled plasma chemical vapor deposition (ICP-CVD), or high-density plasma chemical vapor deposition (HDP-CVD), etc. In some cases, more complex deposition schemes may be used, which may include cyclic deposition operations accompanied by other operations (e.g., etching, inhibition, and / or passivation).

[0040] Unfortunately, many of these deposition processes introduce significant impurities into the silicon-containing film. These impurities can include, for example, fluorine, carbon, hydrogen, and nitrogen. These elements can negatively impact various physical and electrical properties of the resulting device. For instance, impurities in silicon oxide can lead to relatively high wet etching rates, which are associated with lower quality silicon oxide film systems. Furthermore, the presence of these impurities can negatively affect leakage current and breakdown voltage in the resulting device, making such a film unsuitable for electrical insulation applications.

[0041] Because precursors are used to deposit silicon-containing films, carbon, hydrogen, and nitrogen may be incorporated into the silicon-containing films. For example, aminosilane-based precursors are commonly used in vapor deposition techniques. In addition to the desired silicon, these aminosilane-based precursors also include carbon, hydrogen, and nitrogen. Under typical deposition conditions for silicon oxides, significant amounts of carbon, hydrogen, and nitrogen are undesirably incorporated into the silicon oxide film during deposition.

[0042] Various techniques can be employed to reduce carbon, hydrogen, and nitrogen impurities. For example, deposition conditions can be controlled to minimize impurity incorporation. In a particular example, the impurity concentration in silicon oxide films can be reduced by performing deposition at relatively high temperatures (e.g., above approximately 900°C). However, in some cases, high deposition temperatures may be too limiting.

[0043] In another example, halogen-based silicon-containing precursors can be used instead of aminosilane-based precursors. Exemplary halogen-based silicon-containing precursors include, but are not limited to, silicon tetrachloride (SiCl₄), dichlorosilane (SiH₂Cl₂), diiodosilane (SiH₂I₂), etc. Many halogen-based silicon-containing precursors contain little or no carbon, nitrogen, and / or hydrogen, especially compared to common aminosilane-based precursors, such as trimethylaminosilane (also known as 3DMAS, with the chemical formula C₆H₁₉N₃Si). For example, although dichlorosilane and diiodosilane each contain two hydrogen atoms, the Si:H ratio is relatively high at 1:2. In contrast, in trimethylaminosilane, the Si:H ratio is much lower at 1:19. Because halogen-based silicon precursors contain relatively less carbon, nitrogen, and hydrogen than aminosilane-based precursors, these elements are incorporated into the silicon oxide film in smaller quantities during deposition. However, halogen species are known to attack the metal in the processing chamber where the deposition is performed, and the metal etched away from the processing chamber may deposit on the substrate being processed. Therefore, the halogen-based precursor method is difficult to implement and may cause degradation of the processing equipment and poor defect performance on the substrate.

[0044] Fluorine impurities in silicon-containing films can originate from several different sources. In many cases, fluorinated chemicals are periodically used to clean the processing chambers where deposition takes place. The goal of this cleaning is to remove the film accumulated on the surface of the internal chambers. After the cleaning operation, residual fluorine may remain on the chamber surface and may eventually enter the silicon oxide film deposited in the chamber. Since fluorine is introduced via the chamber cleaning operation, it is understood that this cleaning may introduce fluorine into the silicon oxide film, regardless of the deposition scheme used to form the silicon oxide film. Furthermore, in these or other cases, a specific deposition scheme may be used to deposit the silicon-containing film, wherein the specific deposition scheme involves exposing the substrate to NF3 or other fluorinated chemicals. This fluorinated chemical is particularly useful in the context of gap filling, where silicon oxide is deposited in recessed features with a high depth-to-width ratio. These features can be very difficult to fill uniformly without forming voids or seams within them. In one example, a deposition-etch-deposition (“deposition-etch-deposition”) scheme is used, in which deposition, etching, and / or passivation operations are cycled together as the feature is filled with a silicon-containing material. The etching ensures that the feature remains sufficiently open to allow further deposition of the silicon-containing material without closing the feature and creating voids. However, this etching operation typically involves exposing the substrate to NF3 or other fluorinated chemicals, which incorporate fluorine into the silicon-containing film.

[0045] In another example, a suppression-based deposition scheme is used, in which suppression, deposition, and / or passivation operations are cycled together as the feature is filled with a silicon-containing material. This deposition scheme can be referred to as inhibitor-controlled exposure (ICE) deposition. This suppression involves exposing the substrate to NF3 or a similar chemical to selectively suppress deposition at or near the top of the feature, thereby promoting a bottom-up filling mechanism that fills the feature without creating voids or seams. While both the deposition-etch-deposition scheme and the suppression-based deposition scheme involve periodic exposure to NF3 or a similar chemical, it is understood that NF3 can have different effects (e.g., etching vs. suppression) depending on the other processing conditions used.

[0046] In either case, exposing the substrate to NF3 or other fluorinated chemicals results in the introduction of fluorine impurities into the silicon-containing film. To reduce fluorine impurities, the aforementioned impurity-free passivation process can be used, which involves exposing the substrate to a plasma generated from argon, hydrogen (H2), and oxygen (O2). This plasma typically has a relatively high concentration of oxygen. In one example, the H2 flow rate for a 4-station chamber is approximately 2 slm, the O2 flow rate for a 4-station chamber is approximately 2 slm, and the Ar flow rate for a 4-station chamber is approximately 10 slm. This plasma is typically generated at an RF power of approximately 1250 W to approximately 2500 W (e.g., for a chamber with four stations, each station is used to process a 300 mm substrate), and the substrate is exposed to the plasma for approximately 5 to approximately 10 seconds during each repetition. The pressure in the reaction chamber of the 4-station chamber can be approximately 1 Torr to approximately 10 Torr, or approximately 2 Torr. When this impurity-free passivation operation is used during deposition, the fluorine content in the film is lower than that without the passivation operation. For example, in various cases of depositing the silicon-containing material via a deposition-etch-deposition mechanism or a suppression-based deposition mechanism, the passivation operation can reduce the fluorine content in the film by about one or two orders of magnitude. As an example, the typical fluorine concentration of this film is about 1E18 to about 1E21 atoms / cc, or about 1E18 to about 1E20 atoms / cc, where the highest fluorine concentration is usually found at the interface / film depth, where the deposition operation is stopped and an etching or suppression operation is used. Experimental results are further described below.

[0047] Reducing fluorine content through passivation without impurities is beneficial. However, even with passivation, the fluorine concentration remains higher than required for many applications, and further reduction of fluorine content in silicon-containing films would be advantageous.

[0048] This document provides a method and apparatus for combining an impurity reduction operation (sometimes referred to as a passivation operation) to significantly reduce the fluorine content in a membrane. Some disclosed embodiments use processing conditions different from, for example, the passivation operation without impurity reduction described above. For instance, the impurity reduction operation described herein can further reduce the fluorine content in the membrane by one to two orders of magnitude compared to a passivation operation without impurity reduction. In various cases, deposition using the impurity reduction operation can produce silicon oxide films with fluorine content on the order of approximately 1E16 atoms / cc.

[0049] Impurity reduction operations can be performed in the context of depositing silicon-containing materials in recessed features (for example, low aspect ratio features with a depth-to-width ratio as low as about 1:1, high aspect ratio features with a depth-to-width ratio as high as about 100:1, and recessed features with aspect ratios approximately in these ranges). This impurity reduction operation can also be performed in the context of depositing a blanket film of silicon-containing materials (e.g., silicon oxide). Exemplary applications include depositing SiO2 (in some cases SiO2 / SiN) in NAND, DRAM, logic, PCRAM, and MRAM applications.

[0050] Advantageously, this impurity reduction operation also reduces the carbon, hydrogen, and nitrogen content in the silicon-containing film. Therefore, the silicon-containing film produced by this impurity reduction operation is purer than silicon-containing films previously achievable using aminosilane precursors and / or the aforementioned deposition techniques.

[0051] Furthermore, compared to the time required for passivation without impurity reduction, the impurity reduction operation can be performed in significantly less time. In other words, the impurity reduction operation achieves better results (e.g., greater impurity reduction) in less time. Therefore, individual cycle times and overall deposition times are significantly reduced, increasing the throughput of some deposition equipment. This is a significant improvement. [Deposition Methods]

[0052] Some of the disclosed embodiments may involve ALD. ALD is a technique for depositing thin layers of material using sequential self-limiting reactions. The ALD process uses a surface-medium deposition reaction to perform film deposition cyclically on a layer-by-layer basis. As an example, an ALD cycle may include the following operations: (i) delivering / adsorbing a precursor, (ii) purging the precursor from the chamber, (iii) delivering a second reactant and optionally igniting a plasma, and (iv) purging byproducts from the chamber. The reaction system between the second reactant and the adsorbed precursor for forming a film on the substrate surface affects the composition and properties of the film, such as inhomogeneity, stress, wet etching rate, dry etching rate, electrical properties (e.g., breakdown voltage and leakage current), etc.

[0053] Unlike chemical vapor deposition (CVD), ALD processing utilizes a surface-medium deposition reaction to deposit films on a layer-by-layer basis. In one example of ALD processing, a substrate surface comprising a group of active sites is exposed to a vapor phase distribution of a first precursor (e.g., a silicon-containing precursor), wherein the first precursor is in a dose provided to a chamber containing the substrate. Molecules of this first precursor are adsorbed onto the substrate surface, including chemisorbed species and / or physisorbed molecules of the first precursor. It should be understood that, as described herein, when a compound is adsorbed onto the substrate surface, the adsorbed layer may include the compound and derivatives thereof. For example, an adsorbed layer of a silicon-containing precursor may include the silicon-containing precursor and derivatives thereof. After the first precursor is prepared, the chamber is then evacuated to remove most or all of the remaining first precursor from the vapor phase, leaving most or only the adsorbed species. In some embodiments, the chamber may not be completely evacuated. For example, the reactor can be evacuated to sufficiently low partial pressure of the first precursor in the gas phase to slow the reaction. A second reactant (e.g., an oxygen-containing gas) is introduced into the chamber, such that some of these molecules react with the adsorbed first precursor on the surface. In some processes, the second precursor reacts immediately with the adsorbed first precursor. In other embodiments, the second reactant reacts only after a temporary application of an activation source. The chamber can then be evacuated again to remove unbonded second reactant molecules. As mentioned above, in some embodiments, the chamber may not be completely evacuated. Additional ALD cycles can be used to improve film thickness.

[0054] In some embodiments, the ALD method includes plasma activation. As described herein, the ALD method and apparatus described herein may be a conformal film deposition (CFD) method, which is generally described in U.S. Patent Application No. 13 / 084,399 (now U.S. Patent No. 8,728,956), filed April 11, 2011, entitled "PLASMA ACTIVATED CONFORMAL FILM DEPOSITION," and U.S. Patent Application No. 13 / 084,305, filed April 11, 2011, entitled "SILICON NITRIDE FILMS AND METHODS," the entire contents of which are incorporated herein by reference.

[0055] Figures 1A-1E illustrate multiple deposition schemes that can be used in various embodiments. Each exemplary deposition scheme can be performed individually or in combination with any one or more of the other deposition schemes illustrated in Figures 1A-1E. Figure 1A illustrates ALD cycle 101A, which is modified to include an impurity reduction operation. The x-axis represents time. In this example, ALD cycle 101A includes a preparation operation 102, followed by an optional purge operation 103, followed by an oxidation operation 104, followed by an impurity reduction operation 105, followed by a second optional purge operation 106. The impurity reduction operation 105 is omitted in an ALD without impurity reduction.

[0056] In the embodiment of Figure 1A, during dosing operation 102, a first reactant (for example, a silicon-containing precursor, such as an aminosilane-based precursor) is provided to the reaction chamber. This first reactant is allowed to adsorb onto the substrate surface. During purging operation 103, excess first reactant can be removed from the reaction chamber. This can be accomplished by purging and / or evacuating the processing chamber to remove excess first reactant without removing the adsorbed layer. Purging can be performed using any inert gas, such as nitrogen (N₂), argon (Ar), neon (Ne), helium (He), hydrogen (H₂), and combinations thereof.

[0057] During oxidation operation 104, a second reactant (e.g., an oxygen-containing reactant) is provided to the substrate, and the first and second reactants react with each other on the substrate surface to form a silicon-containing material. In some cases, thermal energy is used to drive the reaction between the first and second reactants. In other cases, plasma energy can be used to drive this reaction.

[0058] During impurity reduction operation 105, the substrate is exposed to the impurity reduction plasma, as further described below. During the second purging operation 106, excess reactants and byproducts are removed from the reaction chamber. The second purging operation 106 may involve any of the processing conditions described above with respect to purging operation 103. The purging operation 103 and the second purging operation 106 may involve evacuating the reaction chamber and / or purging the reaction chamber with an inert gas. The ALD cycle 101A of FIG. 1A may be repeated any number of times (e.g., X times in FIG. 1A) to achieve the desired film thickness.

[0059] In similar embodiments, the impurity reduction operation 105 can be performed at different time points during the ALD cycle 101A of FIG1A. Generally, the impurity reduction operation 105 can be performed before, during, or after the purge operation 106 and before the repetition of the subsequent dosing operation 102.

[0060] Figure 1B illustrates another example of deposition via ALD. In this example, ALD cycle 101B includes a reagent preparation operation 102, a purging operation 103, an oxidation operation 104, and a second purging operation 106. These operations are similar to those described above and can be repeated any number of times (e.g., X times in Figure 1B) to increase additional film thickness. After repeating ALD cycle 101B X times, the impurity reduction operation 105 is performed. ALD cycle 101B and the impurity reduction operation 105 (see element symbol 150) can be repeated together any number of times (e.g., Y times in Figure 1B). More frequent performance of the impurity reduction operation 105 results in greater impurity reduction, but also increases processing time and reduces throughput. In various embodiments of deposition according to Figure 1B, X can be approximately 1 to approximately 20, and Y can be approximately 1 to approximately 100. Y can be selected to achieve the desired final film thickness. In a specific embodiment of the method shown in Figure 1B, the deposition rate is on the order of 1 Å / cycle, X=20, and Y=100, producing a film with a total thickness of approximately 2000 Å.

[0061] In these or other embodiments, the impurity reduction operation 105 can be performed periodically, with the frequency based on the film thickness deposited in each cycle. In one example, the impurity reduction operation 105 can be repeated after each deposition of a 1 nm silicon-containing film (e.g., deposit a 1 nm silicon-containing film, perform impurity reduction 105, repeat). More generally, the impurity reduction operation 105 can be repeated after each deposition of a portion / thickness of a 0.1 to 2 nm silicon-containing film. When the silicon-containing film is deposited as a blanket film, the thickness of the blanket film can be used. When the silicon-containing film is deposited in a recessed feature, the film thickness can be measured from the bottom of the feature upwards.

[0062] Figure 1C illustrates an example of deposition via a suppression-based mechanism (e.g., ICE) in a gap-filled background. The process begins with suppression operation 110, in which the substrate is exposed to NF 3 or a similar chemical to selectively suppress deposition near the top of the recessed features on the substrate surface, rather than at the bottom and middle of the recessed features. Next, an ALD cycle 101B is performed, which includes a preparation operation 102, a purging operation 103, an oxidation operation 104, and a purging operation 106. The ALD cycle 101B can be repeated any number of times (e.g., X times in Figure 1C). Next, an impurity reduction operation 105 is performed, as further described below. This impurity reduction operation 105 can be performed instead of a passivation operation without impurity reduction. In the example of Figure 1C, the impurity reduction operation 105 can also be used to completely remove any remaining inhibitor species present on the substrate, which are derived from the suppression operation 110. During ALD cycle 101B, the inhibitor species are slowly eroded away; however, some inhibitor species usually remain. By completely removing any remaining inhibitor species, the impurity reduction operation 105 restores the sidewalls of the feature (e.g., particularly the upper sidewalls where the inhibitor species were previously present) to their initial uninhibited state. This ensures that subsequent inhibition operation 110 can be performed uniformly and reproducibly to target this upper sidewall for inhibition.

[0063] The suppression operation 110, the ALD cycle 101B, and the impurity reduction operation 105 (see element symbol 150) can be repeated together an arbitrary number of times (e.g., Z times in FIG. 1C). Similar to the mechanism of FIG. 1B, increasing the frequency of the impurity reduction operation 105 results in greater impurity reduction, but at the cost of longer processing times and lower throughput. In various embodiments of deposition according to the method shown in FIG. 1C, X can be approximately 1 to approximately 10, and Z can be approximately 1 to approximately 100. In these or other embodiments, the impurity reduction operation 105 can be performed periodically, with the frequency based on the film thickness deposited in each cycle. In one example, the impurity reduction operation 105 can be repeated after each deposition of a 1 nm silicon-containing film (e.g., deposit a 1 nm silicon-containing film, perform impurity reduction 105, repeat). More generally, the impurity reduction operation 105 can be repeated after each deposition of a portion / thickness of a silicon-containing film of about 0.1 to about 20 nm, or about 0.1 nm to about 10 nm. When the silicon-containing material is deposited in the recessed feature, the thickness of the silicon-containing film can be measured from the bottom of the feature upwards.

[0064] Figure 1D illustrates an example of deposition via a deposition-etch-deposition mechanism in a gap-filled background. The process begins with an ALD cycle 101B, which can be performed X times. Next, an etching operation 120 is performed to partially etch away the silicon-containing material previously deposited in the recessed features, ensuring that the features are not closed / blocked during deposition. This etching operation 120 may involve exposing the substrate to NF3 or other etching chemicals (e.g., often fluorine-containing chemicals), which in various embodiments may be provided in plasma form. The ALD cycle 101B and the etching operation 120 (see component symbol 153) can be repeated any number of times (e.g., Y times in Figure 1D). Next, an impurity reduction operation 105 is performed, as further described below. The ALD cycle 101B, the etching operation 120, and the impurity reduction operation 105 (see component symbol 154) can be repeated any number of times (e.g., Z times in Figure 1D). In various embodiments of deposition according to the method shown in Figure 1D, X can be approximately 1 to approximately 1000, Y can be approximately 1 to approximately 1000, and Z can be approximately 2 to approximately 5. X and Y can be the same or different. In many cases, X is greater than Y, such that a majority (e.g., at least about 50%, at least about 75%, or at least about 90%) of the silicon-containing film system is deposited before the etching operation 120 and the impurity reduction operation 105. In various cases, X can be determined based on the size of the filled feature.

[0065] In these or other embodiments, the impurity reduction operation 105 can be performed periodically, with the frequency based on the film thickness deposited in each cycle. Generally, the impurity reduction operation 105 can be repeated after each deposition of a portion / thickness of a silicon-containing film of about 0.1 to about 20 nm, or about 0.1 nm to about 10 nm. When the silicon-containing film is deposited in a recessed feature, the film thickness can be measured from the bottom of the feature upwards.

[0066] Figure 1E illustrates an example of deposition via chemical vapor deposition. The method begins with reactant delivery operation 130, in which a silicon-containing reactant and an oxygen-containing reactant are simultaneously delivered to a reaction chamber, where they react with each other to deposit a silicon-containing material on the substrate surface. This reaction is driven by thermal or plasma energy. Next, an impurity reduction operation 105 is performed, as further described below. The reactant delivery operation 130 and the impurity reduction operation 105 (see element symbol 155) can be repeated together any number of times (e.g., X times in Figure 1E). In various embodiments of deposition according to the method shown in Figure 1E, X can be approximately 1 to approximately 1000, for example, approximately 1 to approximately 100 or approximately 1 to approximately 10. In these or other embodiments, the impurity reduction operation 105 can be performed periodically, with the frequency based on the film thickness deposited in each cycle. In one example, the impurity reduction operation 105 can be repeated after each deposition of a 10 nm silicon-containing film (e.g., deposit a 10 nm silicon-containing film, perform impurity reduction 105, repeat). More generally, the impurity reduction operation 105 can be repeated after each deposition of a portion / thickness of a silicon-containing film of about 0.1 nm to about 20 nm or about 0.1 nm to about 10 nm.

[0067] While the above describes embodiments of ALD and CVD, it will be understood that some of the disclosed embodiments can be implemented in conjunction with any deposition process involving plasma. Non-limiting examples include RPCVD, RPALD, ICP-CVD, and HDP-CVD. In various embodiments, a single reactant can be used to form a film in a plasma-based environment, and impurity reduction operations can still be used to reduce impurities in the film. [Processing conditions for impurity reduction operations]

[0068] In various embodiments, the impurity reduction operation involves exposing a substrate to plasma generated by a plasma-generating gas, wherein the plasma-generating gas comprises an inert gas and hydrogen (e.g., H₂). The plasma-generating gas system is substantially oxygen-free (e.g., O₂ and other oxygen-containing species). As used herein, a "substantially" oxygen-free plasma-generating gas may contain trace amounts of oxygen; however, oxygen and oxygen-containing species are not intended to be provided as part of the plasma-generating gas. In various embodiments, the inert gas includes argon. Alternatively or additionally, other inert gases (e.g., helium, neon, krypton, etc.) may be used in some cases. In some cases, the plasma-generating gas may further include nitrogen (e.g., N₂). An exemplary flow rate of the inert gas for a 4-station chamber may be about 2 to about 60 slm. In some cases, the inert gas flow rate may be at least about 2 slm, at least about 5 slm, at least about 10 slm, at least about 20 slm, at least about 30 slm, or at least about 40 slm. In these or other cases, the flow rate of the inert gas may be less than 60 slm, less than 50 slm, less than 40 slm, less than 30 slm, or less than 20 slm. Exemplary flow rates of hydrogen (e.g., H₂) may be less than 0.5 and less than 5 slm. In some cases, the flow rate of hydrogen may be at least about 0.5 slm, at least about 0.1 slm, at least about 0.5 slm, at least about 1 slm, at least about 2 slm, or at least about 3 slm. In these or other cases, the flow rate of hydrogen may be less than 5 slm, less than 4.5 slm, less than 4 slm, or less than 3.5 slm. When using nitrogen (e.g., N₂), exemplary flow rates may be as high as about 30 slm, and in some cases as high as about 20 slm or as high as about 10 slm.

[0069] For a chamber with four stations, the plasma can be generated at RF power levels including approximately 1000 to approximately 6000 W, or approximately 1000 to approximately 5000 W (for HF RF of 13.56 MHz capacitively coupled plasma), and approximately 0 W to approximately 5000 W, or 0 W to approximately 3000 W, or approximately 0 W to approximately 2000 W (for LF RF of 400 kHz (or 50 kHz to 2 MHz) plasma). In other words, the RF power can be provided at a single frequency (HF only) or at dual frequencies (e.g., HF and LF). In some cases, for a chamber with four stations, HF RF for 13.56 MHz capacitively coupled plasma can be provided at power levels of at least approximately 1000 W, at least approximately 2000 W, or at least approximately 3000 W. In these or other cases, for a chamber with four stations, HF RF for 13.56 MHz capacitively coupled plasma can be provided at power levels of less than 6000 W, less than 5000 W, less than 4000 W in some cases, or less than 3000 W. In these or other cases, LF RF can be omitted. In other embodiments, for a chamber with four stations, LF RF for 400 kHz (or 50 kHz to 2 MHz) plasma can be provided at power levels of at least about 1 W, at least about 10 W, at least about 50 W, at least about 100 W, at least about 500 W, or at least about 1000 W. In these or other cases, for a chamber with four stations, LF RF for a 400 kHz (or 50 kHz to 2 MHz) plasma can be provided at power levels below about 5000 W, about 3000 W, or about 2000 W (e.g., below 1500 W, below 1000 W, below 500 W, or below 200 W). These power levels are suitable for substrates with a diameter of about 300 mm and can be scaled according to different substrate sizes. Exemplary frequencies include, for example, 13.56 MHz, 27 MHz, and 60 MHz, but these frequencies are not intended to be limiting. During plasma exposure operation, the plasma may have a duty cycle of about 10% and about 100%. The plasma can be any type of plasma. In some cases, the plasma is capacitively coupled plasma. In other cases, the plasma is inductively coupled plasma or microwave plasma. In some embodiments, the plasma is a distal plasma. In some embodiments, the plasma is generated by electron cyclotron resonance (ECR).

[0070] During the impurity reduction operation, the pressure in the reaction chamber can be maintained from about 0.5 to about 20 Torr. In various embodiments, this pressure may be at least about 0.5 Torr, at least about 1 Torr, at least about 5 Torr, or at least about 10 Torr. In these or other cases, the pressure may be less than about 20 Torr, less than about 15 Torr, or less than about 10 Torr. The substrate can be placed in a substrate support, which may be temperature-controlled. In some cases, the substrate can be heated or cooled, for example, through the substrate support, during the impurity reduction operation. Exemplary substrate support temperatures may be from about -400°C to about 1400°C, from about -40°C to about 1000°C, or from about 150°C to about 650°C. In some cases, the substrate support is maintained at a temperature of at least about 150°C, at least about 200°C, at least about 300°C, or at least about 400°C. In these or other cases, the substrate support may be maintained at a temperature below about 650°C, about 600°C, about 500°C, about 400°C, about 300°C, or about 200°C.

[0071] During the impurity reduction operation, the substrate may be exposed to plasma for approximately 0.2 to approximately 120 seconds. In various embodiments, the duration of plasma exposure may be at least approximately 0.2 seconds, at least approximately 0.5 seconds, at least approximately 0.1 seconds, or at least approximately 0.2 seconds. In these or other embodiments, the duration of plasma exposure may be less than approximately 120 seconds, less than approximately 10 seconds, less than approximately 1 second, or less than approximately 0.5 seconds. In many cases, the desired impurity reduction is achieved very rapidly, typically less than 1 second. This represents a significant improvement over the aforementioned existing passivation methods (e.g., reduced processing time), where existing passivation methods require an exposure time of at least 5-10 seconds.

[0072] In many cases, this impurity reduction operation can be performed at significantly higher flow rates of hydrogen and inert gases compared to passivation without impurity reduction. Another difference between this impurity reduction operation and passivation without impurity reduction is the omission of oxygen from the plasma-generating gas. In passivation without impurity reduction, oxygen is supplied at a high flow rate. Conversely, in the impurity reduction operation, oxygen is omitted from the plasma-generating gas. Furthermore, this impurity reduction operation is typically performed at a higher RF power level than passivation without impurity reduction. As a result of these differences, this impurity reduction operation is substantially more efficient at removing fluorine from the silicon-containing membrane compared to passivation without impurity reduction (e.g., by about one to two orders of magnitude in time saving), as further described in the experimental section below. Advantageously, this impurity reduction operation also reduces the concentrations of carbon, hydrogen, and nitrogen in the membrane.

[0073] Another advantage of the disclosed impurity reduction operation is that it can be performed in situ. In other words, it can be performed in the same reaction chamber where the silicon-containing film is deposited. Although the impurity reduction operation can be performed in a separate chamber from the deposition chamber (e.g., transferring the substrate between multiple chambers as needed), there is no need to provide a separation chamber for this purpose. Suitable apparatus is further described below in the apparatus section. [Processing conditions for deposition operations]

[0074] As explained with respect to Figures 1A-1E, the impurity reduction operations described herein can be implemented in many different settings using various reaction mechanisms. Therefore, the embodiments described herein are not intended to be limited to a particular group of deposition conditions. However, certain exemplary conditions are provided as guidance.

[0075] In various embodiments of deposition via a method involving atomic layer deposition cycles (e.g., as described with respect to Figures 1A-1D), one or more of the following reaction conditions may be used. During the preparation operation, the silicon-containing reactant is supplied to the reaction chamber at a flow rate of about 150 sccm to about 900 sccm. The silicon-containing reactant is allowed to adsorb onto the substrate surface. The silicon-containing reactant may be a silane, and in many cases an aminosilane. Exemplary aminosilanes include, but are not limited to, tris(dimethylamino)silane, bis(tributylamino)silane, 1,1,1,3,3,3-hexamethyldisilazane, cycloazane, tetra(dimethylamino)silane, trisilylamine, bis(diethylamino)silane, etc. Aminosilanes include at least one nitrogen atom bonded to a silicon atom, but may also contain hydrogen, oxygen, halogens, and carbon. Examples of aminosilanes are mono-, di-, tri-, and tetra-aminosilanes (H3Si(NH2)4, H2Si(NH2)2, HSi(NH2)3, and Si(NH2)4, respectively), as well as substituted mono-, di-, tri-, and tetra-aminosilanes, such as tert-butylaminosilanes, methylaminosilanes, tert-butylsilaneamines, bis(tert-butylamino)silanes (SiH2(NHC(CH3)3)2(BTBAS), tert-butyl silanylaminoformate, SiH(CH3)-(N(CH3)2)2, SiHCl-(N(CH3)2)2, (Si(CH3)2NH) 3. Di(di(dibutylamino)silane) (DSBAS), di(isopropylamino)silane (DIPAS), bis(diethylamino)silane (BDEAS), etc. A further example of an aminosilane is trisilylamine (N(SiH3)3). Various other silanes are also possible.

[0076] Exemplary silica-containing reactants include, but are not limited to, silanes, polysilanes, halosilanes, and aminosilanes. Silanes contain hydrogen and / or carbon groups, but do not contain halogens. Polysilanes may have the chemical formula (H3Si-(SiH2)n-SiH3), where n [>]1. Examples of silanes include silanes (SiH4), disilanes (Si2H6), trisilanes, tetrasilanes, and organosilanes such as methylsilanes, ethylsilanes, isopropylsilanes, tributylsilanes, dimethylsilanes, diethylsilanes, di-tert-butylsilanes, allylsilanes, dibutylsilanes, thexylsilanes, isopentylsilanes, tributyldisilanes, di-tert-butyldisilanes, tetraethyl n-silate (also known as tetraethoxysilane or TEOS), etc.

[0077] Exemplary silica-containing reactants include polysilanes (H3Si-(SiH2)n-SiH3), such as silanes, disilanes, trisilanes, tetrasilanes, and trisilylamines, wherein n [>]1.

[0078] In some embodiments, the silicon-containing reactant is an alkoxysilane. Alkoxysilanes that can be used include, but are not limited to, the following: H x-Si-(OR) y, where x = 1-3, x+y = 4, and R is a substituted or unsubstituted alkyl group; and H x(RO) y-Si-Si-(OR) yH x, where x = 1-2, x+y = 3, and R is a substituted or unsubstituted alkyl group.

[0079] Examples of silica-containing reactants include: methylsilane; trimethylsilane (3MS); ethylsilane; butane; pentasilane; octasilane; heptasilane; hexasilane; cyclotetrasilane; cycloheptasilane; cyclohexasilane; cyclooctasilane; cyclopentasilane; 1,4-dichloro-2,3,5,6-tetrasilcyclohexane; diethoxymethylsilane (DEMS); diethoxysilane (DES); dimethoxymethylsilane; dimethoxysilane (DMO) S); methyl-diethoxysilane (MDES); methyl-dimethoxysilane (MDMS); octamethoxydodecylsiloxane (OMODDS); tri-butoxydisilane; tetramethylcyclotetrasiloxane (TMCTS); tetraoxymethylcyclotetrasiloxane (TOMCTS); triethoxysilane (TES); triethoxysiloxane (TRIES); and trimethoxysilane (TMS or TriMOS).

[0080] In some embodiments, the silicon-containing precursor may be an aminosilane having hydrogen atoms, such as bis(diethylaminosilane), diisopropylaminosilane, tributylaminosilane (BTBAS), or trimethylaminosilane (3DMAS). Aminosilane precursors include, but are not limited to, the following: Hx-Si-(NR)y, where x = 1-3, x + y = 4, and R is an organic or hydride group.

[0081] In some embodiments, a halogenated silane or a halosilane may be used, wherein the silane comprises at least one hydrogen atom. The halosilane may have the chemical formula SiXaHy, where X = Cl, F, I, or Br, and a + y = 4, where a [>] 1. Halogenated silanes can have the chemical formula SiXaHy(CH3)z, where X = Cl, F, I, or Br, and a + y + z = 4, where a [>]1. Examples of halosilanes are iodosilanes, bromosilanes, chlorosilanes, and fluorosilanes. Although halosilanes (especially fluorosilanes) can form reactive halide species that can etch silicon materials, in some embodiments described herein, the silicon-containing precursor is not present when the plasma is ignited. Specific chlorosilanes include tetrachlorosilane (SiCl 4), trichlorosilane (HSiCl 3), dichlorosilane (H 2SiCl 2), monochlorosilane (ClSiH 3), chloroallyl silane, chloromethyl silane, dichloromethyl silane, dichlorodimethyl silane, chloroethyl silane, tertiary butylchlorosilane, di-tertiary butylchlorosilane, chloroisopropyl silane, chloro-secondary butyl silane, tertiary butyldimethylchlorosilane, trihexyldimethylchlorosilane, and monochlorotrimethyl silane, etc.

[0082] Examples of silicon-containing reactants include siloxanes, alkyl siloxanes, or hydrocarbon-substituted siloxanes, or nitrogen- and carbon-containing reactants. Example siloxanes include linear siloxanes, cyclic siloxanes, and cage-like siloxanes. Example siloxanes include 2,4,6,8-tetramethylcyclotetrasiloxane (TMCTS), heptamethylcyclotetrasiloxane (HMCTS), sesquisiloxanes, disiloxanes (e.g., pentamethyldisiloxane (PMDSO) and tetramethyldisiloxane (TMDSO)), and trisiloxanes, such as hexamethyltrisiloxane and heptamethyltrisiloxane. Alkyl siloxanes include a central silicon atom, wherein one or more alkyl groups are bonded to the central silicon atom, and one or more hydrogen atoms are bonded to the central silicon atom. In some embodiments, any one or more of the alkyl groups comprises 1-5 carbon atoms. The hydrocarbon groups may be saturated or unsaturated (e.g., alkenes (e.g., vinyl groups), alkynes, and aromatic groups). Examples include, but are not limited to, trimethylsilane (3MS), triethylsilane, pentamethyldisilane ((CH3)2Si-CH2-Si(CH3)3), and dimethylsilane (2MS). Furthermore, disilane, trisilane, or other higher silanes may be used instead of monosilanes. In some embodiments, one silicon atom may have a carbon-containing or hydrocarbon group attached thereto, and one silicon atom may have a hydrogen atom attached thereto. Examples of nitrogen-containing carbon-containing reactants include methyl-substituted disilazanes and trisilazanes, such as tetramethyldisilazane and hexamethyltrisilazane.

[0083] Examples of silicon-containing reactants include siloxanes, such as cyclotetrasiloxanes (e.g., heptamethylcyclotetrasiloxane (HMCTS) and tetramethylcyclotetrasiloxane). Other cyclic siloxanes may also include, but are not limited to, cyclotrisiloxanes and cyclopentasiloxanes. Other examples of suitable precursors for the deposition of oxygen-doped silicon carbide films include linear siloxanes, such as, but not limited to, disiloxanes, such as pentamethyldisiloxane (PMDSO), tetramethyldisiloxane (TMDSO), hexamethyltrisiloxane, and heptamethyltrisiloxane. For undoped silicon carbides, examples of suitable precursors include monosilanes substituted with, for example, one or more alkyl, alkene, and / or yne groups comprising 1-5 carbon atoms. Examples include, but are not limited to, trimethylsilane (3MS), dimethylsilane (2MS), triethylsilane (TES), and pentamethyldisilane. Disilane, trisilane, or other higher silanes may be used instead of monosilanes. One example of the disilanes from the alkylsilane classification is hexamethyldisilane (HMDS). Other examples of disilanes from the alkylsilane classification may include pentamethyldisilane (PMDS). Other types of alkylsilanes may include alkylcarbosilanes, which may have a branched polymeric structure in which carbon atoms are bonded to silicon atoms and alkyl groups are bonded to silicon atoms. Examples include dimethyltrimethylsilylmethane (DTMSM) and bis-dimethylsilylethane (BDMSE). For the deposition of nitrogen-doped silicon carbide (SiNC) films, suitable precursors include, for example, alkyl diasilicones, and possible compounds comprising an amino group (-NH₂) and an alkyl group, each bonded to one or more silicon atoms. Alkyl diasilicones include diasilicones and alkyl groups bonded to disilicon atoms. Examples include 1,1,3,3-tetramethyldiasilicon (TMDSN). An inert gas may be provided along with the silicon-containing reactants. In one example, argon is provided at a rate of about 1-20 slm, and nitrogen (e.g., N₂) is provided at a rate of about 0 slm to about 30 slm. Additionally, hydrogen (H₂) may be provided at a flow rate of about 0 slm to about 5 slm. The pressure in the reaction chamber may be maintained at about 0.6 Torr to about 20 Torr. The substrate can be placed on a temperature-controlled substrate support, wherein the substrate support can be maintained at a temperature of about 150°C to about 650°C.

[0084] During the purge and second purge operations, the reaction chamber may be evacuated and / or purged with a non-reactive gas to remove unadsorbed reactants and reaction byproducts. Similarly, other gases may be present in the purge gas. In one example, the purge gas includes argon at a flow rate of approximately 1 slm to approximately 20 slm, nitrogen (e.g., N₂) at a flow rate of approximately 0 slm to approximately 30 slm, hydrogen (e.g., H₂) at a flow rate of approximately 0 slm to approximately 5 slm, oxygen (e.g., O₂) at a flow rate of approximately 0 slm to approximately 5 slm, and nitrous oxide (e.g., N₂O) at a flow rate of approximately 0 slm to approximately 5 slm. The chamber pressure and substrate support temperature may be as described above regarding the dosing operation.

[0085] During the oxidation operation, the substrate surface is oxidized and cleaned with RF plasma. A gas can flow into the reaction chamber, wherein the gas includes at least one oxygen-containing reactant. Examples of oxygen-containing reactants include, but are not limited to, oxygen (O₂), nitrous oxide (N₂O), ozone (O₃), carbon monoxide (CO), carbon dioxide (CO₂), etc. Similarly, other gases can be provided. In one example, the following gases can be provided during the oxidation operation: argon at a flow rate of approximately 1-20 slm, nitrogen (e.g., N₂) at a flow rate of approximately 0 slm to approximately 30 slm, hydrogen (e.g., H₂) at a flow rate of approximately 0 slm to approximately 5 slm, oxygen (e.g., O₂) at a flow rate of approximately 0.5 slm to approximately 5 slm, and nitrous oxide (e.g., N₂O) at a flow rate of approximately 0 slm to approximately 5 slm. For a 4-station chamber, RF power in the range of approximately 500 W to approximately 6000 W can be provided. Pressure and temperature can be as described above regarding the preparation operation.

[0086] When using a suppression operation (e.g., see suppression operation 110 in Figure 1C), one or more of the following conditions may be used during the suppression operation: A suppression gas is supplied to the reaction chamber at a flow rate between about 10 sccm and about 300 sccm. Examples of suppression gas species include nitrogen species, halogen species, and hydrogen species. However, any species that adsorbs onto the substrate surface, reacts with the substrate surface, or otherwise interacts with the substrate surface to passivate it and suppress subsequent deposition may be used. In various embodiments, the suppression operation may be based on plasma suppression or thermal suppression. During plasma-based suppression, the structure is exposed to plasma generated from the suppression gas to form the inhibitor species, also referred to as the inhibitor species. Examples of suppression gases include nitrogen-containing gases, halogen-containing gases, and hydrogen-containing gases. Specific examples include nitrogen trifluoride (NF3), molecular nitrogen (N2), molecular hydrogen (H2), ammonia (NH3), amines, glycols, diamines, amino alcohols, thiols, or combinations thereof. In some embodiments, the suppressing gas is a fluorine-containing gas, such as NF3, CHxFy, where x+y=4 and y is an integer greater than or equal to 1, and sulfur hexafluoride (SF6). In some embodiments, the suppression operation may be based on a thermal suppression process. For example, the suppression operation may be performed by exposing the structure to a gas containing the suppressing species under conditions in which the suppressing species react with the substrate surface (e.g., without exposing the substrate to plasma during the suppression operation).

[0087] In some embodiments, the plasma system is suppressed to generate a halogen-containing gas. Examples include NF3, CH3F, CH2F2, CHF3, CF4, SF6, CH3Cl, CH2Cl2, CHCl3, and CCl4. This forms -F, -Cl, or other halogen-terminated surfaces at various depths of the gap (but mostly near the top of the sidewalls), wherein the halogen-terminated surfaces passivate the surface and suppress subsequent deposition. During suppression operation 110, the halogen-containing gas or other suppressing gas may be about 0.5% to about 10%, about 1% to about 5%, or about 2% of the total volumetric flow rate of the chamber or other plasma generation space, wherein the remaining flow rate is an inert gas such as N2, Ar, and He.

[0088] For a 4-station chamber, when using plasma, plasma can be generated at an RF power level of approximately 500 W to approximately 2000 W. The substrate can be exposed to the plasma for approximately 0.1 seconds to approximately 10 seconds. The substrate support temperature can be approximately 200°C to approximately 650°C. The pressure in the reaction chamber can be approximately 0.6 Torr to approximately 10 Torr.

[0089] When using an etching operation (e.g., see etching operation 120 in Figure 1D), one or more of the following conditions may be used during the etching operation: An etching gas is supplied to the reaction chamber at a flow rate of about 50 sccm to about 500 sccm. In one example, the etching gas includes NF3. In other cases, other etching gases may be used. In various embodiments, the etching gas may include nitrogen and / or halogens, such as fluorine or chlorine. Similarly, other gases may be supplied to the reaction chamber, such as one or more gases described above with respect to suppression operation 110. Typically, many of the same gases may be used for both suppression and etching, with lower flow rates typically causing suppression and higher flow rates typically causing etching. The substrate may be exposed to a plasma generated by the etching gas and / or other gases. For a 4-station chamber, the plasma may be generated at an RF power level of about 750 W to about 8000 W. The substrate may be exposed to the plasma for about 1 second to about 300 seconds. The substrate support temperature may be about 200 °C to about 650 °C. The pressure in the reaction chamber can be from approximately 0.6 Torr to approximately 2 Torr.

[0090] In the case of deposition via chemical vapor deposition (e.g., see Figure 1E), one or more of the following conditions can be used: The substrate can be simultaneously exposed to a first reactant (e.g., a silicon-containing reactant, as described above) and a second reactant (e.g., an oxygen-containing reactant, as described above). Simultaneously, the substrate can be exposed to an energy source (e.g., thermal energy and / or plasma energy) to drive the vapor-phase reaction between the first and second reactants. This reaction produces a silicon-containing material, which is deposited on the substrate surface. The silicon-containing reactant is supplied at a flow rate of about 150 sccm to about 900 sccm. The oxygen-containing reactant is supplied at a flow rate of about 500 sccm to about 20,000 sccm. The pressure in the reaction chamber can be maintained at about 2 Torr to about 20 Torr. When the reaction is driven by thermal energy, the substrate support can be maintained at a temperature of about 550°C to about 650°C. When the reaction is driven by plasma energy, the substrate support can be maintained at a temperature of about 200°C to about 650°C, and the plasma can be generated at an RF power level of about 750 W to about 5000 W for a 4-station chamber. During each cycle (e.g., as shown in FIG1E, each cycle includes reactant delivery operation 130 and impurity reduction operation 105), the substrate can be exposed to the first and second reactants, and to the energy source driving the reaction for about 0.1 seconds to about 10 seconds. [equipment]

[0091] The embodiments described herein can be implemented on any suitable equipment. Suitable equipment will include at least a processing chamber, a plasma generator for generating plasma in the processing chamber, and a controller configured to perform one or more of the methods described herein.

[0092] Figure 2 schematically illustrates an embodiment of a processing station 200, which can be used to deposit materials using atomic layer deposition (ALD) and / or chemical vapor deposition (CVD), wherein either ALD or CVD can be driven by thermal or plasma energy. The processing station 200 can be used to implement any of the embodiments described herein, including, for example, the embodiments shown in Figures 1A-1E. For simplicity, the processing station 200 is illustrated as a standalone processing station having a processing chamber body 202 for maintaining a low-pressure environment. However, it will be understood that multiple processing stations 200 can be included in a shared processing facility environment. Furthermore, it will be understood that in some embodiments, one or more hardware parameters of the processing station 200 (including those discussed in detail herein) can be programmatically adjusted by one or more computer controllers.

[0093] Processing station 200 is in fluid communication with reactant delivery system 201 for delivering process gas to distribution spray head 206. Reactant delivery system 201 includes an optional mixing container 204 for mixing and / or blending the process gas delivered to spray head 206. One or more mixing container inlet valves 220 control the introduction of process gas into mixing container 204. Similarly, spray head inlet valve 205 controls the introduction of process gas into spray head 206. In another embodiment, reactant delivery system 201 may keep the reactants separated from each other until they are delivered to the inside of chamber body 202.

[0094] Some reactants (e.g., BTBAS) are stored in liquid form and then transported to the processing station after vaporization. For example, the embodiment of Figure 2 includes a vaporization point 203 for vaporizing liquid reactants to be supplied to mixing container 204. In some embodiments, vaporization point 203 may be a heated vaporizer. Reactant vapor generated from this vaporizer can condense in a downstream delivery line. Exposure of incompatible gases to the condensed reactants can generate particulate matter. This particulate matter can cause line blockage, impede valve operation, contaminate substrates, etc. Some methods for addressing these problems involve purging and / or evacuating the delivery line to remove residual reactants. However, purging the delivery line can increase the processing station's cycle time and reduce processing station throughput. Therefore, in some embodiments, the delivery line downstream of vaporization point 203 may be thermally tracked. In some examples, mixing container 204 may also be thermally tracked. In a non-limiting example, the pipeline downstream of vaporization point 203 has a rising temperature profile of approximately 150°C extending from approximately 100°C to mixing vessel 204.

[0095] In some embodiments, the reactant liquid can be vaporized at a liquid injector. For example, the liquid injector can inject a pulse of liquid reactant into a carrier gas flow upstream of the mixing container. In one embodiment, the liquid injector can vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another embodiment, the liquid injector can atomize the liquid into dispersed droplets, which are subsequently vaporized in a heated delivery line. It will be understood that smaller droplets vaporize more quickly than larger droplets, thus reducing the delay between liquid injection and complete vaporization. Faster vaporization reduces the pipe length downstream of vaporization point 203. In one embodiment, the liquid injector can be directly mounted to the mixing container 204. In another embodiment, the liquid injector can be directly mounted to the spray head 206.

[0096] In some embodiments, a liquid flow controller located upstream of vaporization point 203 may be provided to control the mass flow of liquid for vaporization and delivery to treatment station 200. For example, the liquid flow controller (LFC) may include a thermal mass flow meter (MFM) located downstream of the LFC. The plunger valve of the LFC may then be adjusted in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller electrically connected to the MFM. However, using feedback control to stabilize the liquid flow may take one or more seconds. This may prolong the dosing time of the liquid reactants. Therefore, in some embodiments, the LFC may be dynamically switched between a feedback control mode and a direct control mode. In some embodiments, the LFC may be dynamically switched from a feedback control mode to a direct control mode by disabling the sensor and the PID controller of the LFC.

[0097] The spray head 206 distributes the processing gas toward the substrate 212. In the embodiment shown in FIG2, the substrate 212 is located below the spray head 206 and is shown positioned on the base 208. It will be understood that the spray head 206 may have any suitable shape and may have any suitable number and configuration of ports to distribute the processing gas to the substrate 212.

[0098] In some embodiments, the micro-volume 207 is located below the spray head 206. Performing ALD and / or CVD processing in a micro-volume, rather than the overall volume of the processing station, reduces reactant exposure and sweeping frequency, reduces the frequency of adjustments to processing conditions (e.g., pressure, temperature, etc.), and limits the exposure of the processing station robot to processing gases. Exemplary micro-volume sizes include, but are not limited to, volumes between 0.1 liters and 2 liters. This micro-volume also impacts throughput. Due to the decrease in deposition rate / cycle time, cycle time is also significantly reduced. In some cases, the latter effect is significant enough to improve the overall throughput of a module for a given target film thickness.

[0099] In some embodiments, the base 208 may be raised or lowered to expose the substrate 212 to the micro-volume 207 and / or to change the capacity of the micro-volume 207. For example, during the substrate transfer stage, the base 208 may be lowered to allow the substrate 212 to be mounted on the base 208. During the deposition process stage, the base 208 may be raised to position the substrate 212 within the micro-volume 207. In some embodiments, the micro-volume 207 may completely surround a portion of the substrate 212 and the base 208 to create a high flow resistance region during the deposition process.

[0100] Optionally, the base 208 may be lowered and / or raised during a portion of the deposition process to adjust the processing pressure, reactant concentration, etc., within the micro-volume 207. In one embodiment, maintaining the processing chamber body 202 at a baseline pressure during the deposition process, lowering the base 208 allows for the evacuation of the micro-volume 207. Exemplary ratios of micro-volume to processing chamber volume include, but are not limited to, volume ratios from about 1:200 to about 1:10. It will be understood that in some embodiments, the base height may be programmably adjusted by a suitable computer controller.

[0101] In another embodiment, adjusting the height of the base 208 allows for variations in plasma density during plasma activation and / or processing cycles included in the deposition process. At the end of the deposition process stage, the base 208 can be lowered during another substrate transfer stage to allow the substrate 212 to be removed from the base 208.

[0102] While the exemplary micro-volume alteration examples described herein relate to an adjustable-height base, it will be understood that in some embodiments, the position of the spray head 206 relative to the base 208 can be adjusted to change the capacity of the micro-volume 207. Furthermore, it will be understood that the vertical position of the base 208 and / or the spray head 206 can be changed by any suitable mechanism within the scope of this disclosure. In some embodiments, the base 208 may include a rotation axis for rotating the orientation of the substrate 212. It will be understood that in some embodiments, one or more of these exemplary adjustments can be performed programmatically by one or more suitable computer controllers.

[0103] Referring back to the embodiment shown in Figure 2, the spray head 206 and base 208 are electrically connected to the RF power supply 214 and the matching network 216 to power the plasma. In some embodiments, the plasma energy can be controlled by controlling one or more of the following: processing station pressure, gas concentration, RF source power, RF source frequency, and plasma power pulse duration. For example, the RF power supply 214 and matching network 216 can be operated at any suitable power to form a plasma with the desired free radical species composition. Examples of suitable power are included above. Similarly, the RF power supply 214 can provide RF power at any suitable frequency. In some embodiments, the RF power supply 214 can be configured to independently control high-frequency and low-frequency RF power sources. Exemplary low-frequency RF frequencies may include, but are not limited to, frequencies from about 50 kHz to about 200 kHz. Exemplary high-frequency RF frequencies may include, but are not limited to, frequencies from about 1.8 MHz to 2.45 GHz. It will be understood that any suitable parameters can be adjusted individually or continuously to provide the plasma energy used for surface reactions. In a non-limiting example, the plasma power can be pulsed intermittently to reduce ion bombardment of the substrate surface compared to a continuously powered plasma.

[0104] In some embodiments, plasma can be monitored in situ using one or more plasma monitors. In one approach, plasma power can be monitored using one or more voltage and current sensors (e.g., VI probes). In another approach, plasma density and / or process gas concentration can be measured using one or more optical emission spectroscopy (OES) sensors. In some embodiments, one or more plasma parameters can be programmatically adjusted based on measurements obtained from the in-situ plasma monitor. For example, an OES sensor can be used in a feedback loop to provide programmable control of the plasma power. It will be understood that in some embodiments, other monitors can be used to monitor characteristics of the plasma and other processes. These monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0105] In some embodiments, plasma can be controlled via input / output control (IOC) sequence instructions. In one example, instructions for setting the plasma conditions used in a plasma treatment stage may be included in the corresponding plasma activation formulation stage of a deposition treatment formulation or an impurity reduction formulation. In some cases, treatment formulation stages may be sequentially arranged such that all instructions for the deposition treatment stage are executed simultaneously with that treatment stage. In some embodiments, instructions for setting one or more plasma parameters may be included in a formulation stage preceding the plasma treatment stage. For example, a first formulation stage may include instructions for setting the flow rate of an inert gas and / or reactant gas, instructions for setting the plasma generator to a power setpoint, and time delay instructions for the first formulation stage. A subsequent second formulation stage may include instructions for activating the plasma generator, and time delay instructions for the second formulation stage. A third formulation stage may include instructions for disabling the plasma generator, and time delay instructions for the third formulation stage. It will be understood that these formulation stages may be further subdivided and / or repeated in any suitable manner within the scope of this disclosure.

[0106] In some deposition processes, plasma impacts last for several seconds or longer. In some embodiments, very short plasma impacts can be used. These very short plasma impacts are on the order of 10 ms to 1 second, typically about 20 to 80 ms, with 50 ms being a specific example. Such very short RF plasma impacts require extremely rapid plasma stabilization. To achieve this, the plasma generator can be configured to preset the impedance matching system to a specific voltage and allow frequency fluctuation. High-frequency plasma can be generated at an RF frequency of approximately 13.56 MHz. In the various embodiments disclosed herein, this frequency system is allowed to fluctuate to values ​​different from standard values. By allowing this frequency fluctuation while fixing the impedance matching at a predetermined voltage, the plasma can be stabilized very quickly, which can be important when using very short plasma impacts associated with certain deposition cycle types.

[0107] In some embodiments, the temperature of the base 208 can be controlled via the heater 210. Furthermore, in some embodiments, pressure control of the deposition processing station 200 can be provided via a butterfly valve 218. As shown in the embodiment of FIG2, the butterfly valve 218 regulates the vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, the pressure control of the processing station 200 can also be adjusted by changing the flow rate of one or more gases introduced into the processing station 200.

[0108] One or more processing stations can be included in a multi-station processing tool. Figure 3 shows a schematic diagram of an embodiment of a multi-station processing tool 300, which has an inbound load lock chamber 302 and an outbound load lock chamber 304, one or both of which may include a remote plasma source. A robot 306 under atmospheric pressure is configured to move a substrate or wafer from a carrier loaded via a transfer box 308 into the inbound load lock chamber 302 through an atmospheric port 310. The robot 306 places the substrate on a base 312 in the inbound load lock chamber 302, closes the atmospheric port 310, and evacuates the load lock chamber. If the inbound load lock chamber 302 includes a remote plasma source, the substrate can be exposed to remote plasma processing within the load lock chamber before being guided into the processing chamber 314. Furthermore, the substrate can be heated in the inbound load lock chamber 302 to remove, for example, moisture and adsorbed gases. Next, the chamber transfer port 316 to the processing chamber 314 is opened, and another robot (not shown) places the substrate into the reactor and onto the base of the first station shown in the reactor for processing. Although the embodiment illustrated in FIG3 includes a load lock chamber, it will be understood that in some embodiments, the wafer may be supplied directly to the processing station. In various embodiments, soaking gas is directed to the station as the substrate is placed on the base 312 by robot 306.

[0109] The illustrated processing chamber 314 includes four processing stations, numbered 1 to 4 in the embodiment shown in FIG. 3. Each station has a heated base (shown as 318 of station 1) and a gas line inlet. It will be understood that in some embodiments, each processing station may have different or multiple uses. For example, in some embodiments, the processing stations may switch between ALD and PEALD processing modes. Additionally or alternatively, in some embodiments, processing chamber 314 may include one or more matched pairs of ALD and plasma-enhanced ALD processing stations. Although the illustrated processing chamber 314 includes four stations, it will be understood that processing chambers according to this disclosure may have any suitable number of stations. For example, in some embodiments, the processing chamber may have five or more stations; while in other embodiments, the processing chamber may have three or fewer stations.

[0110] Figure 3 illustrates an embodiment of a wafer handling system 390 for transferring substrates within a processing chamber 314. In some embodiments, the wafer handling system 390 can transfer substrates between various processing stations and / or between a processing station and a load lock chamber. It will be understood that any suitable wafer handling system can be used. Non-limiting examples include wafer carousels and wafer handling robots. Figure 3 also illustrates an embodiment of a system controller 350 for controlling the processing conditions and hardware status of the processing tool 300. The system controller 350 may include one or more memory devices 356, one or more mass storage devices 354, and one or more processors 352. The processors 352 may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc. In some embodiments, the system controller 350 includes machine-readable instructions for performing operations (e.g., the operations described herein).

[0111] In some embodiments, system controller 350 controls all activities of processing tool 300. System controller 350 executes system control software 358, which is stored in mass storage device 354, loaded into memory device 356, and executed on processor 352. Alternatively, control logic may be hard-coded into system controller 350. Application-specific integrated circuits, programmable logic devices (e.g., field-programmable gate arrays, or FPGAs) may be used for these purposes. In the following discussion, wherever "software" or "coding" is used, functionally equivalent hard-coded logic may be used therein. System control software 358 may include a plurality of instructions for controlling: time, gas mixing, gas flow rate, chamber and / or station pressure, chamber and / or station temperature, substrate temperature, target power level, RF power level, substrate base, chuck and / or holder position, and other parameters of a particular process performed by processing tool 300. System control software 358 may be configured in any suitable manner. For example, subroutines or control objects of various processing tool components can be programmed to control the operation of the processing tool components required to perform processing according to the disclosed method. The system control software 358 can be coded in any suitable computer-readable programming language.

[0112] Broadly speaking, a controller can be defined as an electronic device having various integrated circuits, logic, memory, and / or software to receive commands, issue commands, control operations, permit cleaning operations, permit endpoint measurements, and so on. The integrated circuit may include a chip storing program instructions in firmware form, a digital signal processor (DSP), a chip defined as a special application integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers executing program instructions (e.g., software). Program instructions may be instructions that communicate with the controller in the form of various independent settings (or program files) that define operating parameters used to perform specific processing on, or for, or for the system. In some embodiments, the operating parameters may be part of a formulation defined by the process engineer to achieve one or more treatment steps during processing of the grains of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafers.

[0113] In some embodiments, the controller may be part of or coupled to a computer that is integrated and coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be located in the “cloud”, or all or part of the FAB master computer system and may allow remote access to substrate processing. The computer may allow remote access to the system to be able to monitor the current process of machining operations, review the history of past machining operations, review trends or performance measures from plural machining operations, change parameters of the current processing, set processing steps after the current processing, or start a new processing. In some examples, a remote computer (e.g., a server) may provide a processing recipe to the system over a network, wherein the network may include a LAN, or an Internet network. The remote computer may include a user interface and be capable of inputting or writing parameters and / or settings which are then transmitted to the system from the remote computer. In some examples, the controller receives instructions in the form of data that are specific parameters for each processing step to be performed during one or more operations. It should be understood that the said parameters may be specific to the type of processing to be performed, and the type of tool the controller is configured to connect or control. Accordingly, as described above, the controller may, for example, be distributed by recourse to including one or more discrete controllers that operate in a network connection with each other and towards a common purpose (e.g., steps and controls described herein). Examples of controllers distributed for this purpose will be one or more integrated circuits located on the chamber communicating with one or more integrated circuits of a remote setup (e.g., located on a platform layer or as part of a remote computer) and combined to control steps on the chamber.

[0114] Without limitation, exemplary systems may include plasma etching chambers or modules, deposition chambers or modules, spin-wash chambers or modules, metal plating chambers or modules, cleaning chambers or modules, edge etching chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, orbital chambers or modules, or other semiconductor processing systems that may be related to or used in the processing and / or manufacturing of semiconductor wafers.

[0115] As described above, depending on the one or more processing steps to be performed by the tool, the controller may be connected to one or more other tool circuits or modules, other tool components, clustered tools, other tool interfaces, adjacent tools, neighboring tools, tools distributed throughout the plant, main computer, another controller, or tools used in material handling to bring wafer containers into and out of the tool locations and / or loading ports of the semiconductor manufacturing plant. [experiment]

[0116] During the experiment, the inventors confirmed that the method described herein can be used to significantly reduce impurities (e.g., F, C, H and / or N) in silicon oxide films. Even with much shorter processing times, these results show a significant improvement over previous standard passivation methods (e.g., a reduction in fluorine concentration of 1 to 2 orders of magnitude).

[0117] Figures 4A-4C show the fluorine concentration at different depths of silicon oxide films deposited according to various methods. Figure 4A shows the results associated with a silicon oxide film deposited using only ALD (e.g., a method similar to that shown in Figures 1A and 1B, but without impurity reduction operation 105). In the ALD-only example of Figure 4A, the fluorine concentration in the silicon oxide film is on the order of approximately 1E17 atoms / cc. The results in Figure 4A show not only the fluorine concentration in the film but also the concentrations of carbon, hydrogen, nitrogen, silicon, and oxygen. Figure 4B shows the results associated with three silicon oxide films deposited using a deposition-etch-deposition scheme and one film deposited without any etching or passivation operations, wherein the deposition-etch-deposition scheme also uses periodic passivation operations without impurity reduction (e.g., a method similar to that shown in Figure 1D, but using passivation operations without impurity reduction instead of impurity reduction operation 105). In the example of Figure 4B, the fluorine concentration in the silicon oxide film is on the order of approximately 1E18-1E19 atoms / cc, and its highest value is located at the interface / depth where the deposition is stopped to perform, for example, the etching operation. Figure 4C shows the results associated with two silicon oxide films 401 and 402 deposited using a deposition-etch-deposition scheme that also employs a periodic passivation operation without impurity reduction, wherein the deposition operation is driven by high-density plasma (HDP). In this example, the fluorine concentration in the film is on the order of approximately 5E19 atoms / cc.

[0118] Figures 5A and 5B show the concentrations of fluorine, carbon, hydrogen, nitrogen, silicon, and oxygen at different depths in silicon oxide films deposited according to the various techniques described herein. In Figure 5A, the silicon oxide film was deposited using continuous thermal CVD without any impurity reduction operation. In Figure 5B, the silicon oxide film was deposited using a modified CVD technique described with respect to Figure 1E, wherein impurity reduction operations were performed periodically throughout the deposition process. These impurity reduction operations were alternated with chemical vapor deposition operations. The results in Figures 5A and 5B are summarized in Figure 6 and Tables 1 and 2 below.

[0119] Figure 6 shows the carbon, hydrogen, and nitrogen concentrations in the silicon oxide films deposited as described in Figures 5A and 5B. Treatment A refers to the results shown in Figure 5A, where the deposition was performed using a continuous thermochemical vapor deposition technique without impurity reduction operations. Treatment B refers to the results shown in Figure 5B, where the deposition was performed using a modified chemical vapor deposition technique (as described with respect to Figure 1E) involving periodic impurity reduction operations during deposition. The concentrations reported in Figure 6 are average concentrations and do not include the very top and very bottom edges of the silicon oxide film. As shown in Figure 6, the impurity reduction operation has a significant effect on the hydrogen concentration in the silicon oxide film (e.g., reducing it from about 7.70% H to about 0.52% H) and the carbon concentration in the film (e.g., reducing it from about 2.68% C to about 0.12% C). This impurity reduction operation also has a noticeable effect on the nitrogen concentration in the silicon oxide film (e.g., from about 1.88% N to about 0.97% N), but this effect is not as significant as that on hydrogen and carbon concentrations. The values ​​reported in Figure 6 are based on RBS and SIMS data. Process A produces a silicon oxide film with approximately 30.3% silicon and approximately 62.0% oxygen (e.g., approximately 92.3% silicon and oxygen in total). In contrast, Process B produces a silicon oxide film with approximately 33.3% silicon and 66.1% oxygen (e.g., approximately 99.4% silicon and oxygen in total). In other words, the film produced by Process B is significantly purer than the film produced by Process A.

[0120] Table 1 shows the different impurity concentrations when comparing treatments A and B in Figure 6. To reiterate, treatment A refers to the results shown in Figure 5A, and treatment B refers to the results shown in Figure 5B. These results generally match those in Figure 6, showing significant reductions in hydrogen and carbon concentrations, and a moderate reduction in nitrogen concentration, when impurity reduction operations are used during deposition. [[] [surface] [1] []] [Impurities] [deal with] [A] [Impurity concentration] [(] [atom] [cc)] [deal with] [B] [Impurity concentration] [(] [atom] [cc)] H 1.53E21 1.13E20 C 5.33E20 2.66E19 N 3.74E20 2.12E20 F 4.96E+18 1.40E+16

[0121] Table 2 presents the concentrations of the different impurities shown in Table 1, where concentrations are reported in atomic percent rather than atoms per cc. The values ​​in Table 2 match those reported in Figure 6 and further include information related to the fluorine concentration in each membrane. [[] [surface] [2] [Impurities] [deal with] [A] [Impurity concentration] [(] [atom] [%) [deal with] [B] [Impurity concentration] [(] [atom] [%) H 7.70 0.52 C 2.68 0.12 N 1.88 0.97 F 0.3 0.00

[0122] The results presented in this section can be used to quantitatively compare silicon oxide films deposited according to the impurity reduction method with those deposited according to the disclosed embodiments. Generally, the impurity reduction operation reduces hydrogen concentration by 93%, carbon concentration by 95%, nitrogen concentration by 43%, and fluorine concentration by 99.7%. These impurity reductions are significant.

[0123] In various embodiments, the silicon oxide film may have any one or more of the following properties: The concentration of fluorine may be on the order of about 1E16 atoms / cc. In some cases, the fluorine concentration may be less than about 9E16 atoms / cc, less than about 5E16 atoms / cc, less than about 2E16 atoms / cc, or less than about 1E16 atoms / cc. The concentration of fluorine may be less than about 0.3% (atomic %) or less than about ~1E-5% (atomic %). The concentration of carbon may be less than about 9E19 atoms / cc or less than about 5E19 atoms / cc. The concentration of carbon may be less than about 2% (atomic %), less than about 1% (atomic %), less than about 0.5% (atomic %), or less than about 0.25% (atomic %). The concentration of nitrogen may be less than about 3E20 atoms / cc. The concentration of nitrogen may be less than about 1.5% (atomic %) or less than about 1% (atomic %).

[0124] Figures 7A and 7B present FTIR data, which confirm that periodic impurity reduction operations significantly reduce the hydrogen concentration in the silicon oxide film (Figure 7A) and increase the silicon and oxygen concentrations in the silicon oxide film (Figure 7B). In Figures 7A and 7B, "Std dep" refers to depositions without impurity reduction operations, while "periodic treatment" refers to depositions involving periodic impurity reduction operations. Hydrogen-related FTIR peaks are expected to be located at wavenumbers of approximately 3675 cm⁻¹ (with respect to -OH stretching), 3300 cm⁻¹ (with respect to -OH stretching), and 1615 cm⁻¹ (with respect to HOH stretching). As shown in Figure 7A, the deposition without impurity reduction operations shows noticeable peaks at these wavenumbers, indicating a significant hydrogen content in the silicon oxide film. In contrast, with the impurity reduction operations, these peaks substantially disappear, indicating a much lower hydrogen concentration. Silicon-related and oxygen-related peaks are expected to be located at wavenumbers of approximately 1200 cm⁻¹ (related to Si-O stretching), 1075 cm⁻¹ (related to Si-O-Si stretching), 815 cm⁻¹ (related to Si-O bending), and 460 cm⁻¹ (related to Si-O out-of-plane). As shown in Figure 7B, both depositions without impurity reduction and depositions involving impurity reduction operations exhibit peaks at these wavenumbers. However, the higher peak numbers in the case of impurity reduction operations indicate the presence of relatively more silicon and oxygen in the silicon oxide film. In other words, fewer impurities are present, and the silicon oxide film is relatively pure. [Summarize]

[0125] While some details have been described for clarity of understanding of the foregoing embodiments, it will be apparent that certain changes and modifications may be made within the scope of the appended claims. It should be noted that many alternative methods exist for implementing the processes, systems, and apparatus of the presented embodiments. Therefore, the presented embodiments are to be considered illustrative rather than restrictive, and are not limited to the details given herein.

[0126] 101A, 101B: ALD loop 102: Preparation Procedure 103: Cleaning Operation 104: Oxidation Operation 105: Impurity Reduction Operation 106: Cleaning Operation 110: Suppression Operation 120: Etching Operation 130: Reactant transport operation 200: Processing Station 201: Reactant Delivery System 202: Processing the chamber body 203: Vaporization point 204: Mixing Container 205: Spray head inlet valve 206: Distribute spray heads 207: Micro-volume 208: Base 210: Heater 212:Substrate 214: RF Power Supply 216: Matching network 218: Butterfly Valve 220: Mixing container inlet valve 300: Multi-site processing tool 302: Inbound load lock chamber 304: Outbound load lock chamber 306: Robot 308: Teleport Box 310: Atmospheric Port 312: Base 314: Processing Chamber 316: Chamber Transmission Port 318: Base 350: System Controller 352: Processor 354: Large-scale storage device 356: Memory device 358: System Control Software 390: Wafer Handling System 401, 402: Silicon oxide films

Claims

1. A method for depositing a doped or undoped silicon-containing film on a substrate, comprising: (a) Exposing the substrate to a first reactant, wherein the first reactant is a silicon-containing reactant; (b) Reacting at least the first reactant in a first plasma to form a doped or undoped silicon-containing material, and depositing a portion of the doped or undoped silicon-containing film on the substrate, the doped or undoped silicon-containing film having a first impurity concentration; (c) Performing an impurity reduction operation prior to completion of deposition of the portion of the doped or undoped silicon-containing film, wherein the impurity reduction operation includes: (i) generating a second plasma from a plasma generating gas, wherein the plasma generating gas includes an inert gas and hydrogen (H2), and wherein the plasma generating gas is substantially oxygen-free (O2); and (ii) exposing the substrate to the second plasma to reduce the first impurity concentration in the doped or undoped silicon-containing film to a second impurity concentration; and (d) repeating at least one of (a) and (b) or (c) until the doped or undoped silicon-containing film is deposited to a final thickness.

2. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 1, wherein the impurity is selected from the group consisting of fluorine, carbon, hydrogen, nitrogen and combinations thereof.

3. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 1, further comprising (e) exposing the substrate to a second reactant, wherein reacting at least the first reactant includes reacting the first reactant with the second reactant to form the doped or undoped silicon-containing film, wherein repeating at least one of (a) and (b) or (c) further includes repeating (e).

4. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 3, wherein the second reactant is an oxygen-containing reactant.

5. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 3, wherein the first reactant and the second reactant are guided into a chamber including the substrate by temporarily spaced pulses.

6. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 3, wherein the first reactant and the second reactant are simultaneously directed into a chamber including the substrate.

7. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 1, wherein the doped or undoped silicon-containing film is deposited in a plurality of recessed features formed on the surface of the substrate, the method further comprising exposing the substrate to etching chemicals to etch the top of the doped or undoped silicon-containing film in the recessed features before the doped or undoped silicon-containing film completely fills the recessed features.

8. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 1, wherein the doped or undoped silicon-containing film is deposited in a plurality of recessed features formed on the surface of the substrate, the method further comprising exposing the substrate to an inhibitory chemical to selectively inhibit deposition near the top of the recessed features rather than at the bottom and middle of the recessed features.

9. A method for depositing a doped or undoped silicon-containing film on a substrate as described in any of claims 1 to 8, wherein the concentration of the second impurity is 10 times less than the concentration of the first impurity.

10. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein after the doped or undoped silicon-containing film reaches the final thickness, the fluorine concentration in the doped or undoped silicon-containing film is on the order of 1E16 atoms / cc.

11. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is about 1E20 atoms / cc or less.

12. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 11, wherein after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is about 5E19 atoms / cc or less.

13. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is about 2% or less (atomic percentage).

14. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 13, wherein after the doped or undoped silicon-containing film reaches the final thickness, the carbon concentration in the doped or undoped silicon-containing film is about 0.5% or less (atomic percentage).

15. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is about 5E20 atoms / cc or less.

16. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 15, wherein after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is about 1.5E20 atoms / cc or less.

17. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is about 5% or less (atomic percentage).

18. The method of depositing a doped or undoped silicon-containing film on a substrate as claimed in claim 17, wherein after the doped or undoped silicon-containing film reaches the final thickness, the hydrogen concentration in the doped or undoped silicon-containing film is about 0.75% or less (atomic percentage).

19. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein after the doped or undoped silicon-containing film reaches the final thickness, the nitrogen concentration in the doped or undoped silicon-containing film is about 3E20 atoms / cc or less.

20. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein after the doped or undoped silicon-containing film reaches the final thickness, the nitrogen concentration in the doped or undoped silicon-containing film is about 1.5% or less (atomic percentage).

21. A method of depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein generating the second plasma system in (c)(i) comprises flowing the inert gas at a rate of about 2 slm to about 60 slm, flowing the hydrogen at a rate of about 0.5 slm to about 5 slm, and generating the plasma at an RF power level, wherein the RF power level comprises HF RF of about 1000 W to about 6000 W and LF RF of about 0 W to about 5000 W.

22. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein in (c)(ii) the substrate is exposed to the second plasma system for less than about 1 second.

23. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein the inert gas in the plasma generating gas includes argon.

24. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein the plasma-generating gas includes nitrogen (N2).

25. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein the first reactant comprises silane.

26. A method for depositing a doped or undoped silicon-containing film on a substrate as claimed in any of claims 1 to 8, wherein the first reactant comprises an aminosilane.

27. An apparatus for depositing a doped or undoped silicon-containing film on a substrate, comprising: Processing chamber; An inlet is provided to the processing chamber to guide the reactants into the processing chamber; A plasma generator for generating plasma in the processing chamber; And the controller, configured to perform any of the methods requested in items 1 through 26.

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