TW202034380A - Method for generating high quality plasma for enhanced atomic layer deposition - Google Patents

Abstract

A method for performing plasma enhanced atomic layer deposition (PEALD) on a substrate includes: flowing a precursor into a process volume over a surface of a substrate, the precursor being configured to adsorb onto the surface of the substrate; performing a first purge of the process volume; flowing an oxidant gas into the process volume that is over the surface of the substrate; applying inductive RF power to the oxidant gas in the process volume to generate a plasma over the substrate, the applying inductive RF power being performed under a zero applied bias condition, the plasma being configured to convert the precursor that adsorbed onto the surface of the substrate into a film product; performing a second purge of the process volume; repeating the operations of the method until a predefined thickness of the film product is deposited onto the surface of the substrate.

Description

Method for producing high-quality plasma for enhancing atomic layer deposition

The embodiment of the present invention relates to plasma assisted atomic layer deposition (PEALD), specifically, relates to the use of inductively coupled plasma (ICP) to assist atomic layer deposition (ALD).

In the context of semiconductor devices and manufacturing, technological progress is characterized by continuous device miniaturization. As the feature size shrinks (>20 nm in DRAM and logic) and the aspect ratio increases (for example, greater than 30 to 1 in 3D NAND structures), the conformal deposition in narrow high aspect ratio features becomes more Important, from a manufacturing point of view, this continues to pose challenges. Plasma Assisted Atomic Layer Deposition (PEALD) has become a promising technology to achieve conformal deposition. The film quality can also be improved by performing ALD at elevated temperatures. However, the use of elevated temperatures to improve film quality is limited by the thermal budget of the device and by the thermal decomposition temperature of the ALD precursor.

The embodiments of the present invention are produced in this context.

Embodiments of the present invention include methods and systems for performing plasma-assisted atomic layer deposition (PEALD), and in some embodiments, more specifically related to the use of inductively coupled plasma (ICP) to assist atomic layer deposition ( ALD). Certain embodiments for performing PEALD involve the use of ICP to deposit silicon dioxide and silicon nitride under substantially zero applied bias conditions, thereby achieving improved film quality over previous methods.

In some embodiments, a method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate is provided, which includes the following method operations: flowing a precursor into a processing volume above the surface of the substrate, the precursor The substance system is configured to be adsorbed on the surface of the substrate; perform the first cleaning process of the processing volume; flow an oxidant gas into the processing volume above the surface of the substrate; apply inductive RF power to the processing volume The oxidant gas in the oxidant gas is used to generate plasma above the substrate, the operation of applying the induced RF power is performed under the condition of zero applied bias voltage, and the plasma is configured to adsorb the precursor on the surface of the substrate Convert into a small amount of film; perform the second row cleaning process of the processing volume; repeat the flow of the precursor, the first row cleaning process, the flow of the oxidant gas, the application of RF power, and the second row cleaning process The operation is performed until a desired thin film of a predetermined thickness is deposited on the surface of the substrate.

In some embodiments, the operation of applying the induced RF power under the condition of zero applied bias increases the isotropic effect of the plasma conversion of the precursor adsorbed on the surface of the substrate.

In some embodiments, the surface of the substrate includes one or more features.

In some embodiments, the features include one or more high aspect ratio features that have a height to width ratio greater than 10 to 1.

In some embodiments, the thin film product is silicon dioxide.

In some embodiments, the precursor is DIPAS, SAM24, or BTBAS.

In some embodiments, the film product provided by the operation of applying inductive RF power has a wafer etch rate relative to thermal oxide in a range of about less than 2.

In certain embodiments, the operation of applying induced RF power provides the film product with an increased density.

In some embodiments, the operation of applying induced RF power provides the film product with an improved stoichiometric ratio.

In some embodiments, the method is performed at a temperature in the range of approximately 300 to 750 degrees Celsius.

In some embodiments, the operation of applying inductive power is performed for a duration in the range of about 0.5 to 3 seconds.

In some embodiments, the operation of applying inductive power is performed at a power in the range of about 50 to 1500 watts.

In some embodiments, the method is performed at a pressure in the range of about 100 to 500 mTorr.

In some embodiments, a method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate is provided, which includes the following method operations: flowing a silicon-containing precursor into a processing volume above the surface of the substrate, The silicon-containing precursor is configured to be adsorbed on the surface of the substrate; perform the first clean-up process of the processing volume; flow an oxidant gas into the processing volume above the surface of the substrate; transfer inductively The power passes through the dielectric window to the oxidant gas in the processing volume to generate a plasma above the substrate. The plasma is configured to convert the silicon-containing precursor adsorbed on the surface of the substrate into a small amount of two Silicon oxide film; perform the second row cleaning process of the processing volume; repeat the flow of the precursor, perform the first row cleaning process, flow the oxidant gas, inductively transfer power, and perform the second row cleaning The processing operation is performed until a predetermined thickness of the silicon dioxide film product is deposited on the surface of the substrate.

In some embodiments, the operation of inductively transferring power is performed under substantially zero applied bias conditions.

In some embodiments, the method is performed at a temperature in the range of approximately 300 to 750 degrees Celsius.

In some embodiments, the method is performed at a pressure in the range of about 100 to 500 mTorr.

In some embodiments, a method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate is provided, which includes the following method operations: flowing a silicon-containing precursor into a processing volume above the surface of the substrate, The silicon-containing precursor is configured to be adsorbed on the surface of the substrate; perform the first cleaning process of the processing volume; flow the nitrogen-containing gas into the processing volume above the surface of the substrate; transfer inductively Power passes through the dielectric window to the nitrogen-containing gas in the processing volume to generate a plasma above the substrate, the plasma is configured to convert the silicon-containing precursor adsorbed on the surface of the substrate into a small amount of nitrogen Silica film; perform the second row cleaning process of the processing volume; repeat the flow of the precursor, perform the first row cleaning process, flow the nitrogen-containing gas, inductively transfer power, and perform the second row The operation of the net treatment is until the silicon nitride film of a predetermined thickness is deposited on the surface of the substrate.

In some embodiments, the operation of inductively transferring power is performed under substantially zero applied bias conditions.

In some embodiments, the method is performed at a temperature in the range of approximately 300 to 750 degrees Celsius.

In some embodiments, the method is performed at a pressure in the range of about 100 to 500 mTorr.

It should be understood that the foregoing represents an overview of certain non-limiting embodiments of the present invention. Other embodiments are obvious to those skilled in the scope of the present invention.

In the following description, many specific details are explained to provide a thorough understanding of the proposed embodiments. The disclosed embodiments can be implemented without some or all of these specific details. In other examples, in order not to obscure the disclosed embodiments, the conventional processing operations will not be described in detail. Although the disclosed embodiments will be described together with specific embodiments, it should be understood that it is not intended to limit the disclosed embodiments.

This article provides methods and systems for performing plasma-assisted atomic layer deposition (PEALD), which can provide higher film quality than previously achievable under a comparable temperature and processing time. Broadly speaking, inductively coupled plasma (ICP) generated in situ is used for PEALD to provide enhanced energy for the deposition process and improve the quality of the film. Compared with previous achievable ones, the improved film quality enables high-quality films to be obtained at lower temperatures and shorter processing times. Moreover, since the film quality can be improved without increasing the temperature, this expands the feasibility of certain precursors, which may otherwise be limited by their thermal decomposition temperature limits.

For example, compared with capacitively coupled plasma (CCP), using ICP for ALD can obtain better films at lower temperatures. For example, an ICP ALD film deposited at 200C may be equivalent to a CCP ALD film deposited at 400C. The upper limit of the deposition temperature depends on the thermal decomposition temperature of the precursor. By using ICP, more energy is applied to the film (for example, applied to the sidewall of the feature), and this can be combined with high temperature (within the thermal stability range of the precursor) to obtain more energy than using CCP ALD can get higher quality films. This can facilitate the use of lower cost precursors in some cases. For example, a lower-cost precursor that decomposes at a given temperature (for example, a lower temperature when the higher-cost precursor decomposes) may not be used with CCP because the film quality is still insufficient even under the thermal upper limit of the precursor. However, in the case of using ICP, lower cost precursors may become available because of the additional energy applied by ICP, which improves the film quality to an acceptable level.

Table 1 below is a chart showing the characteristics of various silicon dioxide precursors commonly used in the industry. [ Table 1 ] BTBAS SAM24 DIPAS Chemical Name Bis(tert-butylamino)silane Bis(diethylamino)silane Diisopropylaminosilane Chemical formula H2Si[NH(C4H9)]2 H2Si[N(C2H5)2]2 H3Si[N{(CH)(CH3)}2] Molar mass (g/mol) 174.3 174.36 131.29 Boiling point ( ^o C) 167 188 116 Density (g/ml) 0.816 0.788 0.756 Operating temperature range (degree Celsius (C)) > 600 C > 350 C > 400 C

The three precursors commonly used in the industry include BTBAS, SAM24, and DIPAS. It should be understood that the chemical structure of these precursors essentially determines the adhesion coefficient, steric hindrance, deposition rate, vapor pressure, and operating temperature range. In particular, it should be noted that the decomposition temperature of a given precursor establishes an upper limit that can be used to perform atomic layer deposition with the given precursor, and therefore it is impossible to improve the quality of the film using the given precursor by increasing the temperature. improve.

Within their stable operating temperature range, BTBAS, SAM24, and DIPAS can provide similar levels of deposition rate, intra-wafer unevenness, inter-wafer unevenness (repeatability), defects, wafer etching rate ratio (WERR , Relative to the wet etching rate of thermal oxide), and stress. Broadly speaking, the precursor itself determines the operating temperature range and deposition rate (based on adhesion coefficient, steric hindrance, vapor pressure). In the operating temperature range of the precursor, the unevenness within the wafer, the unevenness between the wafers, and the defect performance are mainly related to the hardware. Film quality (characterized by WERR, stress performance, and electrical properties) mainly depends on the conversion step of the precursor, including factors such as RF power, RF time, and oxidant gas composition.

Some precursors (such as SAM24 and DIPAS) decompose at relatively low temperatures. For these precursors, there is a risk of decomposition simply by passing the precursor through a hotter object, which may lead to a thermal chemical vapor deposition (CVD) state. This is a very undesirable situation because it is no longer possible to achieve the shape retention sought by ALD processing. In addition, CVD often has poor in-wafer inhomogeneity and is affected by a load effect (change in film thickness) that depends on the pattern density.

However, BTBAS has a higher thermal decomposition temperature and therefore allows much higher temperatures. By using a higher temperature, the characteristics of the resulting film are improved. For example, WERR decreases and is closer to thermal oxide, and electrical properties become better.

Two ways to improve film properties are (1) increase the energy of the entire system by, for example, performing a deposition process at a higher temperature, or (2) increase the amount of RF activation that enters the film. ICP uses the latter, which increases the RF activation into the film during the conversion step, which enables processing at a lower temperature and at the same time produces a better film. In some cases, it is possible to achieve good performance metrics (such as WERR) on blank wafers. However, this will not translate into a high-quality thin film on a patterned substrate because of the high aspect ratio features and other topologies that are difficult to conformally coat. However, ICP can provide enhanced activation deep into the features and along the sidewalls.

According to an embodiment of the present invention, FIG. 1 is a graph showing the deposition rate of the SiO ₂ ALD precursor as a function of temperature. Specifically, the graph shown demonstrates the decomposition limit of SAM24 and also shows the stability of BTBAS at elevated temperatures. Several curves show the relationship between the deposition rate of SAM24 and BTBAS and the base temperature (which defines the temperature of the substrate).

Curves 100 and 102 show the deposition rate of SAM24 as the precursor under low and high RF conditions, respectively. Low RF conditions are generally defined as RF power in the range of about 200 to 2000 W (distributed to 4 stations) and a short RF time range of about 0.15 to 0.5 seconds. High RF conditions are generally defined as the RF power provided in the range of about 2000 to 6000 W (distributed to 4 stations) and the long RF time range of about 0.5 to 1.5 seconds. In some embodiments, the RF power is distributed among a plurality of stations (for example, four processing stations) of the processing tool, so for a single-station processing tool, the aforementioned RF power range can be divided by four, for example. Curves 104 and 106 show the deposition rate of using BTBAS as the precursor under low and high RF conditions, respectively.

As shown in the figure, the deposition rate of SAM24 at 400C actually increases because the heat of the substrate causes the thermal decomposition of the SAM24 flowing through the substrate, which results in a CVD-like mode in which the precursor leaves the gas phase and falls on the substrate surface Therefore, the growth of the film no longer changes with the RF activation.

Therefore, due to the thermal decomposition of SAM24 demonstrated by the results shown, the ALD deposition using SAM24 is controlled at an ALD temperature below about 400C.

However, compared with SAM24, the BTBAS precursor exhibits stability at higher temperatures. It should also be noted that, compared to SAM24, BTBAS exhibits a higher growth rate at the same temperature.

Without being limited by any particular theory of operation, it is assumed that the growth rate at high temperatures is lower because there are fewer Si-OH bonds on the surface for the precursor to attach. At higher temperatures, H is easier to desorb from the film and the surface, and this will result in a lower growth rate and a denser film. When H is contained, Si-OH end-cap bonds are formed, and this reduces the density compared with the Si-O-Si network.

In some embodiments, if the precursor remains stable at elevated temperatures, the deposition is performed at these elevated temperatures, which results in improved film quality. By way of example (but not limitation), in certain embodiments, deposition is performed at temperatures up to about 750°C. In certain embodiments, deposition is performed at temperatures up to about 1000C.

The energy of the system includes the sum of heat energy and RF energy, which together help the resulting film to become more ideally proportioned, denser, and of better quality.

As demonstrated by the results shown, the BTBAS precursor can be operated in the ALD state at temperatures above 550C. This can be used to extend the ALD process beyond the temperature range of other precursors (such as SAM24 and DIPAS).

According to an embodiment of the present invention, FIG. 2 is a graph showing the influence of temperature and RF energy on film quality, where the film quality is measured by WERR (wafer etch rate relative to thermal oxide). The figure shows the results of SiO ₂ deposited by PEALD at various temperatures and high and low RF energies.

For example, for PEALD performed at 50C, when low RF energy is used, the WERR of the obtained film is 14, but when high RF energy is used, the WERR of the obtained film is 7.

For PEALD performed at 550C, when low RF energy is used, the WERR of the obtained film is about 2, but when high RF energy is used, the WERR of the obtained film is about 1.5.

According to an embodiment of the present invention, FIG. 3 is a graph showing the results of SiO ₂ deposition by ICP PEALD and CCP PEALD treatments. Shows the results obtained from the film deposited under varying RF power (for example, 200 to 6000W), RF time (as shown, in seconds), and temperature (for example, 50 to 550C). Specifically, in the graph shown, the relationship between the WERR (relative to thermal oxide) result along the bottom sidewall of the feature and the RF time is shown.

Unexpectedly, compared with PEALD performed using CCP, the quality of the film obtained using PEALD performed using ICP is significantly improved. This can be clearly seen from the results shown because the overall ICP WERR condition (indicated by reference symbol 300) is lower than the result of CCP (indicated by reference symbol 302). That is, under similar process conditions of RF power, RF time, and temperature, compared with the film deposited by CCP treatment, the film deposited by ICP treatment exhibits lower WERR, so it has a better film quality.

It should be understood that the improved film quality produced by using the direct ICP system is a result beyond expectations compared to what was previously achieved using the CCP system. Both ICP and CCP are suitable technologies/systems known in the art for generating plasma for various purposes. And both inductive coupling and capacitive coupling plasma generation are used for PEALD. However, although the direct ICP chamber is widely used in gate etching and metal etching applications, it has not been used in PEALD. Generally, in a direct ICP chamber, the gap between the dielectric window and the substrate is quite large to accommodate plasma circulation and provide appropriate plasma uniformity (for example, in-wafer uniformity for etching performance), and this This results in a larger chamber volume and a longer residence time of the gas in the chamber. Therefore, the direct ICP chamber is not considered suitable for ALD processing, and rapid gas switching is desired in ALD processing to improve productivity, because ALD generally provides good conformal coverage but a low atomic-level growth rate. However, we have found that the use of the direct ICP chamber for PEALD provides an unexpected improvement in film quality, which is beyond what can be expected based on previous results, where the previous results are based on CCP or Achieved by ICP.

The ICP hard system according to an embodiment of the present invention is configured to generate plasma in situ by inductively coupling RF power into the processing chamber to directly generate plasma on the substrate/wafer. Therefore, in contrast to the previous PEALD technology using a remote CCP/ICP plasma source, the method according to an embodiment of the present invention provides "direct" plasma (in this case, direct ICP).

Without being limited by theory, it is generally believed that the ICP processing of the present invention that directly generates plasma in situ can generate a higher density of plasma near the wafer (compared with CCP processed plasma) without simultaneously Affect the bias and directionality of the plasma. This is important for the existing CCP process. Increasing the plasma density requires increasing the RF power, which also increases the bias voltage. Although this increased plasma density generally improves film quality, there is an upper limit to the available density. When the plasma voltage is high enough, film sputtering occurs, which reduces the conformability or causes other film damages, which leads to a decrease in film quality.

However, by using the ICP processing of the present invention, the plasma density and bias voltage are decoupled from each other and can be independently controlled. Therefore, high-density plasma with zero applied bias (or low or minimum bias) is possible, and it is generally believed that this pair provides higher energy to the film, thereby more evenly distributing the energy flux in the features . Broadly speaking, for a given plasma source, it should be understood that the plasma density tends to vary as a function of the wattage of power applied divided by the surface area to which it is applied. It is generally believed that non-ionic species (including, for example, free radicals (such as singlet/trit oxygen), metastable states, and neutral particles) are transported into the feature while minimizing ion bombardment effects. Therefore, a key technical advantage is to transport more free radicals compared to lower density sources. As a result, the precursors are substantially uniformly converted (oxidized) to oxides throughout a given feature, and therefore areas where previous PEALD treatments have shown poor film quality (e.g., bottom sidewall areas of high aspect ratio features) It now exhibits high film quality that matches other areas of the substrate surface (such as the bottom of the feature and the field area). In the case of oxide deposition, there is more H elimination effect and complete oxidation, so a denser film is formed on all surfaces of the entire feature. Therefore, the embodiments of the present invention can deposit a highly conformal and consistently high-quality thin film on the entire surface structure of the substrate, including the difficult-to-achieve high aspect ratio features.

In some embodiments, the plasma density provided at the surface of the substrate is in the range of about 5×10 ¹⁰ to 5×10 ¹² ions/cm ³ . In some embodiments, the percentage of dissociation into free radicals is about 10-16% of the neutral gas density (about 2.5×10 ¹⁴ atoms/cm ³ to 2.5×10 ¹⁵ atoms/cm ³ ). In some embodiments, the ICP source is a planar source and directly generates plasma on the plane of the substrate.

It should be noted that although the ICP-assisted deposition under the condition of zero applied bias is described, it should be understood that this does not necessarily mean that absolute zero bias exists during operation. Because there may be some low bias during chamber operation. However, for the present invention, the zero-bias condition (or substantially zero-bias condition) means that the bias voltage is not intentionally applied in the system. As mentioned above, the ICP source can generate a self-bias voltage that is measurable but usually less than about 20-30 V depending on the plasma conditions.

It should be noted that the results show that the film quality can be achieved by ICP PEALD treatment but at lower temperature, lower RF time, and/or lower RF power to achieve the same film quality as a given CCP PEALD treatment. The ability to achieve the same film quality with a lower RF time can be used to improve throughput in mass manufacturing operations.

Regarding temperature, it should be understood that higher temperatures can be used in CCP processing to improve film quality. However, we have found that by using ICP processing, it is possible to obtain the same film quality at a lower temperature. This is advantageous for several reasons.

High temperature may not be feasible, because if the temperature reaches the thermal decomposition limit of the precursor, it is no longer possible to obtain a better film by further increasing the temperature. Therefore, ICP contributes to film quality previously unavailable for certain precursors, which are limited by their thermal decomposition temperature.

In addition, exposure to high temperatures can be harmful to the device structure on the substrate. Many devices cannot be processed at temperatures higher than a certain temperature and may have a thermal budget. Some non-limiting examples are provided below.

For example, the manufacturing of PCRAM/phase change memory can be controlled at a temperature not exceeding about 200C, because chalcogenide may react, diffuse, or change with the conversion chemicals above this temperature.

In FEOL processing, the temperature limit depends on the device structure and considerations such as the percentage of Ge and whether it is exposed. Therefore, the deposition temperature may be limited to as low as 400°C.

In the back-end manufacturing (BEOL) module/logic processing, due to the risk of copper migration and diffusion, the BEOL processing of all copper metallization can be limited to about 400C.

In DRAM manufacturing, the temperature can be limited to less than 600°C, especially for the interlayer dielectric (ILD) processing steps performed later in the manufacturing process.

MRAM manufacturing is generally limited to about 200-300 C.

In NAND manufacturing, in certain embodiments and certain stages of the manufacturing process, the upper temperature limit may be in the range of about 650 to 700C.

Other emerging technologies (such as ReRAM) may have thermal budget and temperature limitations due to structural sensitivity and/or material composition.

In some embodiments, the PEALD treatment of the present invention is performed at a temperature in the range of about 50 to 750 C; in some embodiments, it is performed at a temperature in the range of about -50 C to 900 C get on.

In some embodiments, for each PEALD cycle, the induction power is applied for a duration in the range of about 0.1 to tens of seconds; in some embodiments, the induction power is applied for a range of about 0.2 to 5 seconds. The duration within.

In some embodiments, for each PEALD cycle, 300 mm wafers are provided with an induction power in the range of about 50 to 12000W; in some embodiments, the power is in the range of about 1000 to 10000W . In some embodiments, the power is about 6000 W. In some embodiments, power is allocated to four processing stations.

Another aspect that can be controlled to provide improved film quality in the ICP PEALD process is the chamber pressure. Broadly speaking, it has been observed that low pressure can provide an improved sidewall WERR. For example (not limiting), in some embodiments, the chamber pressure is in the range of about 0.005 to 2 Torr; in some embodiments, the chamber pressure is in the range of about 0.05 to 1 Torr ; In some embodiments, the chamber pressure is in the range of about 0.08 to 0.8 Torr; in some embodiments, the chamber pressure is in the range of about 0.1 to 0.5 Torr.

Without being limited by any specific theory of operation, it is generally believed that under these pressure conditions, an increase in free radicals reaches the wafer surface (especially the surface in the high AR feature) and causes the thin film WERR to decrease. The low pressure used for deposition will increase the mean free diameter between radicals, which will reduce the quenching (or recombination) of radicals. Therefore, relative to the ion partial pressure, the radical partial pressure is higher. Since radical incidence is isotropic and ion incidence is anisotropic, the increased availability of radicals results in improved activation on the sidewall region. This is an unexpected result, as higher pressures are generally expected to increase the availability and penetration of active species into surface features. However, we have found that lower pressure provides improved sidewall film quality, which is believed to be caused by increased free radical cross-section and increased free radical to ion ratio. It should be understood that the chamber pressure can be optimized so that it is high enough to provide a sufficient concentration of available species for deposition/activation, and at the same time low enough to avoid excessive free radical quenching.

In view of the foregoing, it should be understood that the improved film quality provided by the ICP PEALD process according to the embodiments of the present invention provides significant advantages for device manufacturing under conditions such as those listed above. Improved film quality can be obtained at a given temperature, which provides better device performance (such as electrical properties, stress, life/durability) and yield. The relatively inexpensive precursors with lower thermal decomposition limits can be expanded to produce higher quality films that were previously difficult to obtain. The film quality equivalent to the existing CCP process can be obtained at a lower temperature and/or a lower RF time, thereby meeting a stricter thermal budget and/or increasing production capacity.

Although specific silicon-containing precursors have been discussed, it should be understood that the techniques according to embodiments of the present invention can be applied to any other silicon-containing precursors suitable for PEALD. Non-limiting examples include various chlorosilanes, iodosilanes, halogenated silanes, aminosilanes, and any of other silicon-containing molecules such as SiCl ₄ , SiH ₂ Cl ₂ , Si ₂ Cl ₆ , Si ₃ Cl ₈ , SiH ₃ Cl, SiH(N(CH ₃ ) ₂ ) ₃ (3DMAS, tris(dimethylamino) silane), SiH ₂ (NH ^t Bu) ₂ (BTBAS, bis(tert-butylamino) silane), C ₉ H ₂₉ N ₃ Si ₃ (DTDN-2H2), C ₆ H ₁₇ NSi (DIPAS, bis(isopropylamino) silane), C ₉ H ₂₅ N ₃ Si (TIPAS, tris (isopropylamino) silane) , C ₈ H ₂₂ N ₂ Si (BDEAS, bis(diethylamino)silane), SiH ₄ , (SiH ₃ ) ₃ N, (SiH ₃ ) ₃ N (TSA, trimethylsilylamine), (SiH ₃ ) ₄ Si (NPS, neopentasiloxane).

In addition, although this article discusses the oxidation of silicon-containing precursors to form silicon dioxide films, it should be understood that in other embodiments, the technology of the present invention can be used to produce silicon nitride (SiN) films. In some embodiments, any of the currently disclosed silicon-containing precursors can be used in PEALD processing to conformally deposit SiN films. In these embodiments, the conversion step is a nitridation step, which requires a nitrogen-containing gas (such as N ₂ , N ₂ /H ₂ mixture, NH ₃ ) to flow across the surface of the substrate and inductively generate nitrogen from the nitrogen-containing gas Plasma. It should be understood that any applicable process parameters described herein (including (but not limited to) temperature, RF power, duration of RF power, etc.) can be applied to SiN performed by PEALD technology according to embodiments of the present invention. Film deposition.

According to an embodiment of the present invention, FIG. 4 shows a method for performing plasma-assisted atomic layer deposition. In method operation 400, the substrate is received in a processing chamber for PEALD. In some embodiments, initial preparation operations are performed, such as purging the processing chamber with inert gas, heating the substrate and/or the chamber to a predetermined temperature, and establishing a predetermined pressure in the chamber. At method operation 402, the precursor is flowed into the processing chamber and across the surface of the substrate. The precursor is adsorbed on the surface of the substrate. In method operation 404, a purge operation (for example, using an inert gas) is performed to remove excess precursors and/or by-products from the chamber.

At method operation 406, the oxidant (converted gas) is flowed into the processing chamber and across the surface of the substrate. At method operation 408, RF power is applied to an RF antenna (e.g., a coil), which inductively couples the RF power into the chamber, and specifically, to the oxidant, thereby forming plasma from the oxidant species. The plasma reacts with the adsorbed precursor to convert the adsorbed precursor into a thin film product. In method operation 410, another purge operation (for example, using an inert gas) is performed to remove by-products and other species from the processing chamber.

In method operation 412, it is determined whether the desired thickness of the thin film product has been reached, for example, by determining whether a predetermined number of PEALD processing cycles have been performed. If not, the method returns to method operation 402 to perform the PEALD cycle again. If so, the method ends at operation 414.

According to an embodiment of the present invention, FIG. 5 is a graph that conceptually shows the relationship between the film density and temperature of the PEALD process performed by CCP and ICP. The curve shown represents the film density of PEALD films deposited by CCP and ICP as a function of temperature. Therefore, these curves illustrate the film quality improvement and advantages provided by ICP over CCP processing.

For example, at a temperature T _1, to provide a film having a film density D ₁ by the CCP PEALD deposition processing. At the same temperature T ₁ , the film deposited by the ICP PEALD process (using the same precursor) has a density D ₂ greater than D ₁ . Therefore, ICP processing can provide improved film density at a given temperature.

In certain embodiments, the precursor can be processed by CCP treatment at a significantly higher temperature T ₂ to achieve the film density D ₂ . However, in this case, the ICP treatment can provide a thin film with the same density but obtained at a significantly lower temperature (T ₁ ), thereby reducing the thermal exposure of the device. In some cases, the temperature T ₂ may exceed the thermal budget requirements of a given device to be processed. Therefore, when the quality level (density D ₂ ) is also required, the precursor does not seem to be used for the CCP process. Processing of the device. However, by replacing the ICP process, the same precursor can be used but the required film density level can be reached at a significantly lower temperature to meet the thermal budget requirements.

In some embodiments, the temperature T ₂ may be the approximate thermal decomposition temperature of the precursor. Therefore, it is impossible to further improve the film density by further increasing the processing temperature. However, by using ICP PEALD treatment, the same precursor can be used to achieve a higher film density D ₃ . Therefore, the use of ICP expands the quality of the precursor film beyond the range previously achievable under the limitation of the thermal decomposition temperature of the precursor.

The various embodiments described herein can be implemented in an inductively coupled plasma (ICP) system. 6, an exemplary ICP deposition system or apparatus may include the following: a chamber 1601, which has a gas injector/sprinkler/nozzle 1603 for distributing gas (1605, 1607, 1609) (eg, precursors, Oxidant, and exhaust gas) or other chemicals into the chamber 1601; the chamber wall 1611; the chuck 1613, used to hold the substrate or wafer to be processed 1615, the chuck 1613 may include clamping and de-clamping Electrostatic electrode holding wafer. The chuck 1613 is heated for thermal control, so that the substrate 1615 can be heated to a desired temperature. In some embodiments, the RF power supply 1617 can be used to charge the chuck 1613 to provide a bias voltage according to embodiments of the present invention.

The RF power source 1619 is configured to supply power to the RF antenna/coil 1621 disposed above the dielectric window 1623 to generate plasma 1625 in the processing space above the substrate 1615. In some embodiments, the chamber walls are heated to support heat management and efficiency. The vacuum source 1627 provides vacuum to evacuate the gas from the chamber 1601. The system or equipment may include a system controller 1629 to control some or all operations of the chamber or equipment, such as modulating the chamber pressure, inert gas flow, plasma power, plasma frequency, reactive gas flow (for example, precursor Materials, oxidants, etc.), bias power, temperature, vacuum settings, and other process conditions.

In some embodiments, the system/device may include more than one chamber for processing substrates.

For productivity purposes, ALD systems usually use small-volume chambers that can be filled and drained quickly. However, ICP reactors tend to have significantly larger volumes. Therefore, there is the following problem: how to promote rapid gas switching for ALD in a relatively large volume system. One technique is to continuously drain the non-processing volume space, so during the drain operation of the ALD cycle, only the processing volume space directly above the wafer/substrate needs to be effectively drained. The processing volume can be separated from the non-processing volume space by an air curtain. In addition, rapid gas exchange can be used to modulate gas flow and pressure to accelerate gas delivery and removal from the processing volume.

According to an embodiment of the present invention, FIG. 7 shows a control module 1700 for controlling the above-mentioned system. For example, the control module 1700 may include a processor, a memory, and one or more interfaces. The control module 1700 can be used to control devices in the system based in part on the sensed values. For example only, based on the sensed values and other control parameters, the control module 1700 can control one or more valves 1702, filter heaters 1704, pumps 1706, and other devices 1708. The control module 1700, for example only, receives the sensed value from the pressure gauge 1710, the flow meter 1712, the temperature sensor 1714, and/or other sensors 1716. The control module 1700 can also be used to control the processing conditions during reactant transport and plasma processing. The control module 1700 usually includes one or more memory devices and one or more processors.

The control module 1700 can control the operation of the reactant transport system and the plasma processing equipment. The control module 1700 executes a computer program, including a set of instructions for controlling the following: the processing sequence of a specific process, the temperature of the transmission system, the pressure difference between the two ends of the filter, the position of the valve, the mixing of gas, the chamber pressure, the chamber Temperature, wafer temperature, RF power level, wafer ESC or base position, and other parameters. The control module 1700 can also monitor the pressure difference and automatically switch the vapor reactant delivery from one or more paths to one or more other paths. Other computer programs stored in the memory device and related to the control module 1700 may be used in some embodiments.

There is usually a user interface related to the control module 1700. The user interface may include a display 1718 (such as a display screen, and/or a graphical software display of equipment and/or processing conditions), and a user input device 1720, such as a pointing device, a keyboard, a touch screen, a microphone, etc.

The computer program used to control the transportation of reactants, plasma processing, and other processing in the processing sequence can be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran or others. The processor executes the compiled object code or instruction code to perform the tasks identified in the program.

Control module parameters are related to processing conditions, such as filter pressure difference, processing gas composition and flow rate, temperature, pressure, plasma conditions (such as RF power level and RF frequency), cooling gas pressure, and chamber wall temperature.

System software can be designed or configured in many different ways. For example, many sub-programs or control purposes of the chamber elements can be written to control the operation of the necessary chamber elements to realize creative deposition processing. Examples of programs or program sections for this purpose include substrate positioning codes, process gas control codes, pressure control codes, heater control codes, and plasma control codes.

Although the above-mentioned embodiments have been described in some details for the purpose of clear understanding, obviously, certain changes and modifications can be implemented within the scope of the disclosed embodiments. It should be noted that there are many alternative ways of implementing the processes, systems, and devices of the embodiments herein. Therefore, the embodiments herein are regarded as illustrative rather than restrictive, and the embodiments are not limited to the details provided herein.

100: curve 102: Curve 104: Curve 106: Curve 300: Reference symbol 302: Reference symbol 400: Method operation 402: method operation 404: Method operation 406: method operation 408: method operation 410: method operation 412: method operation 414: method operation 1601: Chamber 1603: Gas injector/sprinkler/nozzle 1605: Gas 1607: Gas 1609: Gas 1611: chamber wall 1613: Chuck 1615: substrate 1617: RF power supply 1619: RF power supply 1621: RF antenna/coil 1623: Dielectric window 1625: Plasma 1627: vacuum source 1629: System Controller 1700: control module 1702: Valve 1704: filter heater 1706: pump 1708: other devices 1710: Pressure Manometer 1712: Flowmeter 1714: temperature sensor 1716: other sensors 1718: display 1720: input device

According to an embodiment of the present invention, FIG. 1 is a graph showing the deposition rate of certain SiO ₂ ALD precursors as a function of temperature.

According to an embodiment of the present invention, FIG. 2 is a graph showing the influence of temperature and RF energy on film quality (measured by WERR).

According to an embodiment of the present invention, FIG. 3 is a graph showing the results of SiO ₂ deposition by ICP PEALD and CCP PEALD treatments.

According to an embodiment of the present invention, FIG. 4 shows a method for performing plasma-assisted atomic layer deposition.

According to an embodiment of the present invention, FIG. 5 is a graph that conceptually shows the relationship between the film density and temperature of the PEALD process performed by CCP and ICP.

According to an embodiment of the present invention, FIG. 6 shows an exemplary ICP deposition system.

According to an embodiment of the present invention, FIG. 7 shows a control module for controlling the above-mentioned system.

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Claims (24)

A method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate, including: Flowing a precursor into a processing volume above the surface of the substrate, the precursor being configured to be adsorbed on the surface of the substrate; Perform the first row net treatment of the treatment volume; Flowing an oxidant gas into the processing volume above the surface of the substrate; Applying induced RF power to the oxidant gas in the processing volume to generate plasma above the substrate. The operation of applying induced RF power is performed under zero applied bias conditions. The plasma is configured to be adsorbed on the substrate The precursor on the surface is converted into a thin film product; Perform the second row net treatment of the treatment volume; The operations of flowing the precursor, performing the first cleaning process, flowing the oxidant gas, applying RF power, and performing the second cleaning process are repeated until the predetermined thickness of the substrate is deposited on the surface of the substrate The film product so far. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 1, wherein the generated plasma has approximately 5 x 10 ¹⁰ to 5 x 10 ¹² ions at the surface of the substrate /cm ^{3 in} the range of density. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 1, wherein the operation of applying induced RF power is performed under a condition of zero applied bias so that the precursor adsorbed on the surface of the substrate The isotropic effect of the plasma transformation of substances is enhanced. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 3, wherein the surface of the substrate includes one or more features. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate according to claim 4, wherein the features include one or more high aspect ratio features having a height to width ratio greater than 10 to 1 . As in claim 1, the method for performing plasma assisted atomic layer deposition (PEALD) on a substrate, wherein the thin film product is silicon dioxide. As claimed in claim 6, the method for performing plasma assisted atomic layer deposition (PEALD) on a substrate, wherein the precursor is DIPAS, SAM24, or BTBAS. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 6, wherein the film product provided by the operation of applying inductive RF power has a range of about less than 2 relative to thermal oxide The wafer etching rate. The method for performing plasma assisted atomic layer deposition (PEALD) on a substrate as in claim 6, wherein the thin film product provided by the operation of applying induced RF power has an increased density. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as in claim 1, wherein the operation of applying induced RF power provides the thin film product with an improved stoichiometric ratio. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 1, wherein the method is performed at a temperature in the range of about 300 to 750 degrees Celsius. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as in claim 1, wherein the operation of applying induced RF power is performed for a duration in the range of about 0.5 to 3 seconds. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as in claim 1, wherein the operation of applying induced RF power is performed at a power in the range of about 50 to 1500 watts. The method for performing plasma assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 1, wherein the method is performed at a pressure in the range of about 100 to 500 mTorr. A method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate, including: Flowing a silicon-containing precursor into a processing volume above the surface of the substrate, the silicon-containing precursor being arranged to be adsorbed on the surface of the substrate; Perform the first row net treatment of the treatment volume; Flowing an oxidant gas into the processing volume above the surface of the substrate; Inductively transfer power through the dielectric window to the oxidant gas in the processing volume to generate a plasma above the substrate, the plasma being configured to convert the silicon-containing precursor adsorbed on the surface of the substrate It is a product of silicon dioxide thin film; Perform the second row net treatment of the treatment volume; Repeat the operations of flowing the silicon-containing precursor, performing the first cleaning process, flowing the oxidant gas, inductively transferring power, and performing the second cleaning process until it is deposited on the surface of the substrate The predetermined thickness of the silicon dioxide film is produced. The method for performing plasma assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 15, wherein the generated plasma has approximately 5 x 10 ¹⁰ to 5 x 10 ¹² ions at the surface of the substrate /cm ^{3 in} the range of density. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as in claim 15, wherein the operation of inductively transferring power is performed under substantially zero applied bias conditions. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 15, wherein the method is performed at a temperature in the range of approximately 300 to 750 degrees Celsius. The method for performing plasma assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 15, wherein the method is performed under a pressure in the range of about 100 to 500 mTorr. A method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate, including: Flowing a silicon-containing precursor into a processing volume above the surface of the substrate, the silicon-containing precursor being configured to be adsorbed on the surface of the substrate; Perform the first row net treatment of the treatment volume; Flowing nitriding agent gas into the processing volume above the surface of the substrate; Inductively transfer power through the dielectric window to the nitriding agent gas in the processing volume to generate a plasma above the substrate, and the plasma is configured to adsorb the silicon-containing precursor on the surface of the substrate The product is converted into silicon nitride film; Perform the second row net treatment of the treatment volume; Repeat the operations of flowing the silicon-containing precursor, performing the first cleaning process, flowing the nitriding agent gas, inductively transferring power, and performing the second cleaning process until the surface of the substrate The silicon nitride film product of a predetermined thickness is deposited on it. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as claimed in claim 20, wherein the generated plasma has approximately 5 x 10 ¹⁰ to 5 x 10 ¹² ions at the surface of the substrate /cm ^{3 in} the range of density. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as in claim 20, wherein the operation of inductively transferring power is performed under the condition of substantially zero applied bias voltage. The method for performing plasma-assisted atomic layer deposition (PEALD) on a substrate as in claim 20, wherein the method is performed at a temperature in the range of about 300 to 750 degrees Celsius. The method of claim 20 for performing plasma-assisted atomic layer deposition (PEALD) on a substrate, wherein the method is performed under a pressure in the range of about 100 to 500 mTorr.

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