Plasma heating to maintain stable showerhead temperature to improve wafer-to-wafer performance

Abstract

Provided herein are methods for maintaining a deposition chamber by plasma heating. The plasma heating can involve heating the showerhead and the deposition chamber, in some cases, using plasma generated from the nitrous oxide gas. The plasma heating is performed between the deposition(s) while the deposition chamber is idle and does not contain a substrate.

Description

Attorney Docket No. 11858-1WO_LAM1P027WOPLASMA HEATING TO MAINTAIN STABLE SHOWERHEAD TEMPERATURE TO IMPROVE WAFER- TO -WAFER PERFORMANCEINCORPORATED BY REFERENCE

[0001] A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in their entireties and for all purposes.BACKGROUND

[0002] Manufacture of semiconductor devices involves depositing one or more conformal thin films on a substrate in an integrated fabrication process. As the devices shrink, conformal layers become thinner and fewer and fewer deposition cycles are used to deposit a film on a substrate. As a result, it is desirable to accurately control film thickness from substrate to substrate. The variation in thickness from substrate to substrate may be known as “wafer-to-wafer variation.” As devices shrink, other forms of variation, e.g., within wafer variation (i.e., layer thickness variations from one position to another position on a single wafer) can also become problematic. Wafer-to-wafer variations and within-wafer variations may depend on a number of factors, including the chamber conditions prior to and during the deposition cycle on a substrate.

[0003] The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.SUMMARY

[0004] Provided herein are methods for maintaining a deposition chamber by plasma heating. One general aspect includes, after performing a first deposition on a first substrate, removing the first substrate from the deposition chamber housing the first substrate. The method further includes performing the plasma heating after removing the first substrate from the deposition chamber. The plasma heating involves a plasma heating phase and a no-Attorney Docket No. 11858-1WO_LAM1P027WO plasma phase. During the plasma heating phase, the deposition chamber is exposed to a plasma generated from a gas to heat a showerhead, and during the no-plasma phase, no plasma is generated in the deposition chamber. When performed, the plasma heating can stabilize the temperature of the showerhead.

[0005] Implementations may include one or more of the following features.

[0006] In some embodiments, the method may further include repeating the plasma heating phase and the no-plasma phase.

[0007] In some embodiments, the method further includes a second deposition on a second substrate. In some embodiments, plasma heating is performed after removing the first substrate from the deposition chamber and prior to introducing the second substrate into the deposition chamber for the second deposition. In some embodiments, the plasma heating is performed for an entire duration after removing the first substrate from the deposition chamber and prior to the second deposition.

[0008] In some embodiments, the plasma heating reduces variation between a first deposition rate for the first deposition and a second deposition rate for the second deposition.

[0009] In some embodiments, the plasma heating reduces variation in the stress between the first deposition and the second deposition.

[0010] In some embodiments, the plasma heating reduces variation in the wafer-to-wafer thickness nonuniformity across wafers between the first deposition and the second deposition. In some embodiments, the nonuniformity in thickness of the wafers produced in the second deposition is at least 10% lower than the first deposition.

[0011] In some embodiments, the plasma heating phase is performed for at least 2 minutes. In some embodiments, the plasma heating phase is performed for a duration between 2 minutes and 20 minutes.

[0012] In some embodiments, no-plasma phase is performed for at least 5 minutes. In some embodiments, no-plasma phase is performed for a duration between 5 minutes and 60 minutes.Attorney Docket No. 11858-1WO_LAM1P027WO

[0013] In some embodiments, the plasma heating phase and the no-plasma phase are repeated two or more times. In some cases, each of the plasma heating phases is performed for the same duration of time. In some embodiments, each of the no-plasma phases lasts for the same duration of time.

[0014] In some embodiments, the plasma heating has a duty cycle between 25% and 40%.

[0015] In some embodiments, the deposition chamber has a pedestal temperature between 140°C and 400°C during the plasma heating.

[0016] In some embodiments, the deposition chamber has a pressure between 2 Torr and 5 Torr during the plasma heating.

[0017] In some embodiments, the gas from which the plasma is generated includes a gas selected from nitrous oxide, carbon dioxide, ammonia, hydrogen, nitrogen, helium, argon, and combinations thereof.

[0018] In some embodiments, nitrous oxide gas is introduced to the deposition chamber at a flow rate between 2000 seem and 18000 seem. In some embodiments, helium is introduced to the deposition chamber at a flow rate no more than 18000 seem. In some embodiments, nitrogen gas is introduced to the deposition chamber at a flow rate no more than 18000 seem. In some embodiments, argon is introduced to the deposition chamber at a flow rate no more than 18000 seem. In some embodiments, ammonia is introduced to the deposition chamber at a flow rate no more than 800 seem.

[0019] In some embodiments, the plasma is generated from a gas using a remote plasma generator.

[0020] In some embodiments, the plasma is generated from a gas using a high-frequency plasma generator. The high-frequency plasma generator may be ignited using 300 W- 2800 W of power.

[0021] In some embodiments, the plasma is generated from a gas using a low-frequency plasma generator. The low-frequency plasma generator may be ignited using no more than 2700 W of power.Attorney Docket No. 11858-1WO_LAM1P027WO

[0022] In some embodiments, the plasma is generated from a gas using a dual-frequency plasma generator.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figures 1A and IB are process flow diagrams depicting the operations of a method in accordance with certain disclosed embodiments.

[0024] Figure 2 shows experimental results from methods in accordance with the disclosed embodiments.

[0025] Figure 3 is a schematic diagram of an example deposition station for performing disclosed embodiments.

[0026] Figure 4 shows a schematic diagram of an example plasma processing apparatus for performing disclosed embodiments.

[0027] Figure 5 is a schematic diagram of an example process tool for performing disclosed embodiments.DETAILED DESCRIPTION

[0028] 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, well-known process operations have not been described in detail to not unnecessarily obscure the disclosed embodiments. While the disclosed embodiments will be described in conjunction with the specific embodiments, it will be understood that it is not intended to limit the disclosed embodiments.

[0029] Provided herein are methods for maintaining the conditions of a deposition chamber by plasma heating. The plasma heating involves heating the showerhead and the deposition chamber between performing depositions on substrates. The plasma heating may involve periodically heating the showerhead and the deposition chamber. The plasma heating is performed while the deposition chamber is idle and does not contain a substrate. The plasma heating may be performed using a plasma generated from nitrous oxide (N2O) gas. The plasma heating methods described herein may be used to maintain a stable temperature ofAttorney Docket No. 11858-1WO_LAM1P027WO the showerhead within the deposition chamber. Certain disclosed embodiments described herein, when used, may reduce the variation of the showerhead temperature during the film deposition process. In some implementations, the plasma heating method may be used to regulate the showerhead temperature in suitable apparatuses or systems that do not have in situ showerhead monitoring or control capabilities. When practiced, the method described herein can mitigate wafer-to-wafer variation (e.g., variation in properties such as thickness of the films deposited on multiple wafers processed sequentially in the process chamber in a batch process), or moderate variations in deposition rates between the depositions.

[0030] The manufacture of semiconductor devices typically involves depositing one or more conformal layers of thin films on a substrate in an integrated fabrication process. For example, some front-end-of-the-line (FEOL) processes may involve the deposition of conformal films by various techniques such as chemical vapor deposition (CVD), atomic layer deposition (ALD), plasma-enhanced chemical vapor deposition (PECVD), and plasma-enhanced atomic layer deposition (PEALD). In some cases, the deposition of the film may involve an apparatus having one or more showerhead(s), within the deposition chamber(s), for distributing the process gases.

[0031] For example, the manufacture of semiconductor devices may involve depositing silicon nitride (e.g., SiN and SiaN4) or silicon oxide (e.g., SiCE) films on a substrate (e.g., a semiconductor wafer). Silicon nitride or silicon oxide may be deposited by any of the above techniques. The deposition process may involve various operations, such as exposing the substrate to one or more precursors (e.g., silicon-containing precursors) and forming silicon nitride or silicon oxide on the substrate. Here, “deposition process” refers to a process that deposits one or more layers of thin films on a substrate in an integrated fabrication process. In some cases, a deposition process that deposits silicon nitride or silicon oxide film on a substrate can include any number of other operations, such as, but not limited to, exposure to a plasma formed in a process gas, such as nitrogen gas (N2). In some embodiments, various operations may be repeated in a deposition process until the films have been deposited to a desired thickness and / or until the deposited films have desired properties.

[0032] In various implementations, thin film deposition may be performed in a deposition chamber having one or more stations (e.g., 4 deposition stations), each of which may house a showerhead to distribute process gases and / or reactants. In various embodiments, in each deposition process, up to four substrates may be processed simultaneously in the depositionAttorney Docket No. 11858-1WO_LAM1P027WO chamber having four stations. After the deposition process, substrates may be removed from the stations, and new substrate(s) may be introduced for the next deposition process.

[0033] In some embodiments, the deposition chamber may be cleaned to remove or etch unwanted species or residual films accumulated inside the deposition chamber during the deposition process. The deposition chamber may be cleaned by exposing the deposition chamber to a plasma generated from one or more process gases, such as nitrogen trifluoride (NF3). Other suitable process gas capable of cleaning can be used. In some embodiments, plasma used for the deposition chamber cleaning may be generated from process gas in a remote plasma generator. In various implementations, the deposition chamber is cleaned after one or more deposition processes, for example, after 3 or more, after 4 or more, or after 5 or more deposition processes. In some embodiments, the deposition chamber is cleaned after completing 5 deposition processes. In various embodiments, this cleaning is performed between the deposition processes, i.e., after removing the substrate(s) following the deposition process and prior to introducing the next substrate(s) for deposition.

[0034] In some embodiments, the deposition chamber may be ‘idle’ for some duration of time. When idle, no deposition process or chamber cleaning process is performed within the deposition chamber. When idle, the deposition chamber does not house any substrate(s). In some embodiments, the deposition chamber may be idle after performing one or more deposition processes, e.g., after performing 4 or more, 5 or more, or 10 or more deposition processes. After the deposition process, the deposition chamber may be idle until new substrate(s) starts being introduced to the deposition chamber for the next deposition process. In some cases, the deposition chamber may be idle after one or more deposition processes and one or more deposition chamber cleaning, and until the substrate(s) are introduced to perform another deposition process. In some embodiments, the deposition chamber may be idle for a short duration of time, while in certain cases, the deposition chamber may be idle for a longer duration of time. For example, the deposition chamber may be idle for at least 10 minutes, at least 1 hour, at least 8 hours, at least 24 hours, between 1 and 7 days, or even longer. In various implementations, the duration of time in which the deposition chamber is idle may be difficult to predict until the next deposition process is scheduled or performed.

[0035] The deposition process may be sensitive to showerhead temperature. For example, variations in the showerhead temperature may affect film properties (such as thicknessAttorney Docket No. 11858-1WO_LAM1P027WO uniformity and stress) and deposition rates. In many cases, the showerhead temperature can continue to change under different deposition chamber conditions, for example, during the deposition process, during the deposition chamber cleaning operation, or when the deposition chamber is idle.

[0036] During the deposition process, the showerhead temperature may rise. In some embodiments, the rise in showerhead temperature may be due to the plasma heating from delivering plasma generated from a process gas to the process chamber via the showerhead during the deposition process. In some instances, the showerhead temperature may continue to rise, or rise until reaching a stable showerhead temperature. During the deposition chamber cleaning operation, the showerhead temperature may increase since many of the deposition chamber cleaning operations may involve exothermic reactions. When the deposition chamber is idle, the showerhead temperature may be low (e.g., ambient temperature), and / or the showerhead temperature may continually decrease for the entire duration of, or at least a portion of, time where the deposition chamber is idle.

[0037] The entire duration of the idle time refers to about 100% of the time after performing one or more deposition processes (i.e., batches) and before new substrates are introduced for the next set or batch of deposition processes in which the deposition chamber is idle. In some embodiments, the “entire duration of the idle time” may refer to a duration less than a strict 100% of the time. For example, the entire duration of the idle time may be at least 90%, at least 95%, at least 98%, or at least 99% of the time the deposition chamber is idle. In some embodiments, certain disclosed embodiments may be performed during the entire time the deposition is idle until a new substrate is provided to the process chamber for processing. This may be performed even if the idle time is long so as to ensure a stable showerhead temperature is already met when the next substrate or batch of substrates is being processed.

[0038] The fluctuations of the showerhead temperature at different deposition chamber conditions and at different times in the deposition chamber history can have a large impact on the resultant film properties. For example, whether the chamber is between deposition operations and / or the duration of the idle period can impact the temperature fluctuation and film properties. Fluctuations can also be caused by conditions such as the number of cleaning operations. Depending on the extent of the showerhead temperature fluctuations during the deposition process for a particular film, e.g., a silicon nitride film, the resultingAttorney Docket No. 11858-1WO_LAM1P027WO films may display variations in film properties. The variations may be within a film deposited on a substrate (e.g., nonuniformity of the thickness), between the substrates that were processed simultaneously during a deposition process, or across the substrates processed in different deposition processes.

[0039] Fluctuations in the showerhead temperature or unstable showerhead temperature can lead to ‘wafer-to-wafer variation’ in the thickness of the film from one substrate to another substrate(s). Wafer-to-wafer variation may be present amongst substrates that are processed in a multi-station chamber. Wafer-to-wafer variation may be present between the substrates that have been processed in two or more separate deposition processes (e.g., processed in sequence). In some embodiments, the resulting film(s) may also have non-uniformity in film thickness across the wafer and / or conformity issues within the wafer. Within-wafer variation refers to a variation in thickness from one position to another position on a single wafer. The film thickness of a substrate may be measured by taking an average film thickness over the surface of the substrate. This may be characterized by “within-wafer non-uniformity.” Within-wafer non-uniformity is defined as the range of measured thickness over a defined number (e.g., 49 points) of locations on the wafer, divided by the average film thickness at these locations. The film may be considered non-uniform when the non-uniformity is above 7%. Wafer-to-wafer non-uniformity is a comparison between wafer-to-wafer variation in thicknesses and the thickness, which may be the average thickness, of the deposited film(s) in the substrate(s) that were simultaneously processed. Within-wafer non-uniformity is a comparison of variation in thickness of one position from other position (which may be the average thickness within a wafer) in a single wafer. The non-uniformity may be quantified using a percentage. For example, the films having wafer-to-wafer variation in the thickness of +50A and the average thickness of the deposited film(s) about 500A have a wafer-to- wafer non-uniformity % that is 10%. In one example where the showerhead is subjected to temperature fluctuations, the wafer-to-wafer non-uniformity of the deposited film may range from about 7% to about 12 or 13%. In another example, a film having within-wafer variation in thickness of +100A and the average thickness of the deposition film of about 2000A has a within-wafer non-uniformity % that is 5%. In one example where the showerhead is subjected to temperature fluctuations, the within-wafer non-uniformity of the deposited film may range from about 1% to about 5%.Attorney Docket No. 11858-1WO_LAM1P027WO

[0040] In some embodiments, the wafer-to-wafer variation in thickness may vary as much as 20% during the continuous and / or repeated deposition cycles.

[0041] Other properties can vary due to fluctuations in the showerhead temperatures. These properties may include but are not limited to, deposition rate, stress, and film profile. The deposition rate may exhibit a variation where the deposition rate generally increases over the different deposition processes. For example, the initial deposition rate may be about 1800 A / min and may steadily increase to about 2100 A / min over the 12 deposition processes. In other instances, the stress of the resultant film can display variations. For example, the stress may range from about -650 MPa to about -485 MPa over the 12 deposition processes.

[0042] The deposition chamber may be cleaned at least once between the deposition processes. For example, the deposition chamber is cleaned after the 4thand / or 8thdeposition processes prior to beginning the 5thand / or 9thdeposition processes, respectively. However, the deposition chamber cleaning process generally does not ‘reset’ the variation in deposition rates and / or film properties over the repeated deposition processes due to the trends of the showerhead temperatures.

[0043] In some implementations, the variation in film properties and / or the deposition rate due to the fluctuations in the showerhead temperature may be more significant when the deposition processes are performed at lower deposition temperatures (e.g., less than 180°C, less than 200°C, or less than 250°C). Here, “fluctuation” refers to when the showerhead temperature varies more than 10%, or more than 20% of the desired deposition temperature. For example, showerhead temperature may fluctuate more than ±10°C, more than ±20°C, or even more than ± 30°C, depending on the pedestal temperature setpoint and deposition process that is running.

[0044] As described, without proper control to maintain stable showerhead temperatures during the deposition process, it can be challenging to control the various properties of the resulting film(s).

[0045] One approach to address the fluctuations in the showerhead temperature is to incorporate plasma preheating of the showerhead and / or chamber before the deposition process to saturate or raise the showerhead temperature. For example, the depositionAttorney Docket No. 11858-1WO_LAM1P027WO chamber and the showerhead(s) may be preheated with plasma generated using nitrous oxide (N2O) gas preheated for a duration of time, e.g., about 10 minutes to about 20 minutes.

[0046] In some embodiments, before the deposition process, plasma preheating may be performed, either before or after chamber cleaning, with the following operating conditions. The temperature of the deposition chamber may be between 100°C and 400°C (e.g., 150°C, 180°C, 200°C, or 250°C). The pressure may be between 1.5 Torr and 6 Torr (e.g., 3 Torr, or 4 Torr). Plasma may be generated using a high-frequency plasma generator or a low- frequency plasma generator. The high-frequency plasma generator may be ignited using up to 3000W (e.g., 300W, 1000W, 250W, or 2750W) of power. The plasma may be generated from a process containing nitrous oxide (N2O), and further include inert gas such as nitrogen (N2), argon (Ar), helium (He). The plasma generated from nitrous oxide may be introduced to the chamber at a flow rate of between 2000 and 20000 seem (e.g., 5000 seem, 10000 seem, or 15000 seem).

[0047] In various implementations, a longer chamber idle period leads to a longer plasma preheating process. When used, the effectiveness of this method for regulating the showerhead temperature can strongly depend on the temperature of the showerhead prior to the plasma preheating process. In many cases, the showerhead temperature may change depending on the state and / or history of the deposition chamber. The showerhead temperature may be different depending on the duration of the chamber idle period, whether the chamber was cleaned, and / or the time lapsed from the previous chamber cleaning or deposition process. These aspects can introduce additional complications in managing the showerhead temperature via plasma preheating.

[0048] As described, different showerhead temperatures prior to plasma preheating may lead to performing plasma preheating at different conditions to reach the optimal showerhead temperature. However, in some cases, the showerhead may not have in situ temperature monitoring capabilities. Without such capabilities, determining appropriate plasma preheating conditions to reach a stable showerhead temperature can be difficult. While a temperature monitoring system or RFTC (Radio Frequency coupled Temperature Control) showerhead may be incorporated to assist in determining plasma preheating conditions, these often can be costly to integrate. Moreover, the plasma preheating is an additional operation performed while the deposition chamber is idle, which in turn, adds toAttorney Docket No. 11858-1WO_LAM1P027WO the idle time between the deposition process, decreasing the throughput of the deposition process.

[0049] Another strategy to regulate the showerhead temperature may involve the plasma heating of the showerhead, or the deposition chamber, or both. In some embodiments, the plasma heating is performed with plasma generated from nitrous oxide gas and is performed while the deposition chamber is idle. The method for the plasma heating may be practiced according to the example operations outlined in Figures 1A and IB below. The method provided herein may be used to regulate the showerhead temperatures for any suitable apparatus or system that does not have in situ showerhead temperature monitoring or control capabilities. While the plasma heating method is particularly useful in cases without showerhead temperature monitors or controls, the method described herein may also be used in apparatuses and systems with such capabilities. When practiced, the plasma heating of the showerhead while the deposition chamber is idle can help mitigate the variations in showerhead temperature. This plasma heating, in turn, can moderate variations in film properties.

[0050] Because the plasma heating described herein does not necessarily involve high-cost hardware (e.g., an RFTC showerhead or temperature-monitoring showerhead), it can be cost-effective compared to the plasma preheating discussed above. In addition, since the plasma heating can be performed while the deposition chamber is idle, it does not impact or reduce the throughput.

[0051] Moreover, the plasma heating can quench or remove fluorine residues and / or other residues that are present on the surface of the showerhead and the deposition chamber. The fluorine residues may be formed on the showerhead during the chamber cleaning process. This is because the chamber cleaning process may involve plasma generated from fluorine- containing gas (e.g., NF3 gas) to clean the deposition chamber. In various embodiments, the showerheads may contain aluminum, and the residual fluorine (e.g., atomic fluorine) on the showerhead surfaces can lead to the formation of aluminum fluoride. The presence of aluminum fluoride on the showerhead can result in various downstream effects. For example, it can introduce defects (such as fluorine defects) into the film during the deposition and can alter the properties of the deposited film. In other instances, aluminum fluoride on the showerhead can reduce the ‘lifetime’ of the showerhead, warranting aAttorney Docket No. 11858-1WO_LAM1P027WO replacement. Hence, incorporating the plasma heating that removes fluorine residues from the showerhead may be advantageous.

[0052] Figure 1A is a process flow diagram illustrating example operations for maintaining a deposition chamber in accordance with certain disclosed embodiments. Method 100 for maintaining the deposition chamber begins with operation 101 where a first substrate is removed from a deposition chamber after performing a first deposition. In operation 103, the plasma heating is performed after removing the first substrate from the deposition chamber. Method 100 can optionally include operation 105, where a second deposition on a second substrate is performed after the plasma heating operation 103. Figure IB is a flow diagram illustrating example operations that may be performed for the plasma heating corresponding to operation 103 in Figure 1A. The plasma heating 103 includes operation 111 and operation 113. Operation 111 is a plasma heating phase where the deposition chamber is exposed to a plasma generated from a process gas. Operation 113 is a no-plasma phase during which the plasma generated from the gas is turned OFF (e.g., RF power is turned off and no plasma is generated) to the chamber. The methods described herein may be used to maintain a stable showerhead temperature during the deposition.

[0053] Details regarding Figure 1A will now be provided. Returning to Figure 1A, method 100 begins with operation 101, where after performing a first deposition on a first substrate, the first substrate is removed from the deposition chamber housing the first substrate.

[0054] The first substrate may be a silicon wafer, e.g., a 200-mm wafer, a 300-mm wafer, or a 450-mm wafer, including wafers having one or more layers of material, such as dielectric, conducting, or semiconducting material deposited thereon. In some embodiments, the substrate may be or include silicon (Si), silicon germanium (SiGe), an oxide such as silicon oxide (SiCF) or silicon nitride. In some embodiments, the first substrate may include one or more features. The feature may be pillars, poles, trenches, via or contact holes, which may be characterized by one or more narrow and / or re-entrant openings, constrictions within the feature, and high aspect ratios. In some embodiments, the feature on the substrate is formed in silicon or polysilicon. In some embodiments, the feature(s) such as a pillar may have an aspect ratio of at least about 1:1, at least about 2:1, at least about 4:1, at least about 6:1, at least about 10:1, or higher. The feature(s) may also have a dimension near the opening, e.g., an opening diameter or line width of between about 10 nm to 500 nm, for example between about 25 nm and about 300 nm. Disclosed methodsAttorney Docket No. 11858-1WO_LAM1P027WO may be performed on substrates with feature(s) having an opening less than about 150 nm. A via, trench or other recessed feature may be referred to as an unfilled feature or a feature. According to various embodiments, the feature profile may narrow gradually and / or include an overhang at the feature opening. A re-entrant profile is one that narrows from the bottom, closed-end, or interior of the feature to the feature opening. A re-entrant profile may be generated by asymmetric etching kinetics during patterning and / or the overhang due to non- conformal film step coverage in the previous film deposition, such as deposition of a diffusion barrier. In various examples, the feature may have a width smaller in the opening at the top of the feature than the width of the bottom of the feature.

[0055] In some embodiments, the first substrate includes an oxide. An example of oxide may be silicon oxide (SiC ). In some embodiments, the feature on the substrate is an oxide material. In some embodiments, the feature on the substrate is formed in silicon oxide.

[0056] In some embodiments, the first substrate includes a nitride. An example of nitride may be silicon nitride (SisN4). In some embodiments, the feature on the substrate is formed in a nitride material.

[0057] By ‘first’ substrate herein refers to one or more substrates that are being processed during a first deposition in a deposition chamber. The deposition chamber may be a multistation chamber having one or more showerheads, that is housing the first substrate(s). In various embodiments, the first deposition may involve depositing silicon nitride on one or more first substrate(s) housed in a deposition chamber.

[0058] The first deposition may involve depositing silicon nitride on a first substrate. For example, the first deposition may deposit silicon nitride on one or more wafers. In some embodiments, the first deposition involves depositing other types of films such as silicon oxide, silicon, silicon carbide, silicon carbonitride, and silicon oxynitride. In some embodiments, the first deposition involves depositing metal films such as metal oxide, metal carbides, metal oxynitride, and metal carbonitride.

[0059] In some embodiments, the first deposition involves chemical vapor deposition. For example, the deposition may be depositing silicon nitride on a wafer via chemical vapor deposition or plasma-enhanced chemical vapor deposition. The first deposition can involve other types of deposition techniques such as, but not limited to, atomic layer deposition and plasma-enhanced atomic layer deposition.Attorney Docket No. 11858-1WO_LAM1P027WO

[0060] In one example, the first deposition involves depositing silicon nitride on the wafer(s) by chemical vapor deposition. During the first deposition, the first substrate may be exposed to one or more precursors (e.g., silicon-containing precursors) and form silicon nitride on the first substrate. In some cases, the first deposition process can include any number of other operations, such as but not limited to, exposure to a plasma formed in process gas, such as nitrogen gas (N2). In some embodiments, during the first deposition, various underlying operations may be repeated until the silicon nitride has been deposited to a desired thickness.

[0061] In operation 101, after performing the first deposition on the first substrate, the first substrate is removed from the depositing chamber.

[0062] Following operation 101, operation 103 may be performed. In operation 103, the plasma heating is performed after removing the first substrate from the deposition chamber. Figure IB describes example operations in the plasma heating operation 103. As depicted in Figure IB, the plasma heating includes the plasma heating phase and the no-plasma phase. During the plasma heating phase (i.e., in operation 111), the deposition chamber is exposed to a plasma generated from a gas to heat the showerhead. In operation 111, plasma generated from a gas may be introduced to the deposition chamber for at least some duration of time. In some embodiments, operation 111 and operation 113 may be repeated periodically.

[0063] After operation 111, operation 113 is performed. During operation 113, gas is turned OFF (e.g., RF power is turned off, and no plasma is generated). In some embodiments, operations 111 and operation 113 are repeated at an interval. For example, operation 111 may be performed after operation 113. When practiced, the plasma heating can stabilize the temperature of the showerhead (e.g., temperature fluctuations less than ±5°C) while the deposition chamber is idle.

[0064] The plasma in operation 111 may be plasma generated from nitrous oxide (N2O) gas. In some embodiments, operation 111 may be practiced with any other suitable plasma. In some embodiments, the plasma may be generated from an inert gas, such as but not limited to, carbon dioxide (CO2), ammonia (NH3), hydrogen (H2), nitrogen (N2), helium (He), argon (Ar), or combinations thereof. In some embodiments, operation 111 may be practiced with plasma generated from a process gas containing nitrous oxide and one or more inert gases. For example, an inert gas mixture used for plasma heating could contain about 80% nitrousAttorney Docket No. 11858-1WO_LAM1P027WO oxide (N2O) gas and about 20% nitrogen (N2), or about 80% carbon dioxide (CO2) and about 20% helium (He), etc. In some embodiments, an inert gas mixture used for plasma heating could contain at least 60%, at least 75%, or at least 80% nitrous oxide. In some embodiments, an inert gas mixture used for plasma heating could contain at least 60%, at least 75%, or at least 80% carbon dioxide.

[0065] In some embodiments, during operation 111, plasma is generated from the process gas(es) introduced to the deposition chamber at various flow rates. The plasma may be generated within the deposition chamber. For example, nitrous oxide, may be introduced to the deposition chamber with a flow rate of at least 2000 seem, at least 5000 seem, at least 7500 seem, at least 10000 seem, at least 12500 seem, at least 15000 seem, no more than 18000 seem, or between 2000 seem and 18000 seem. The plasma may be generated from the nitrous oxide gas inside the deposition chamber. In some embodiments, ammonia may be introduced to the deposition chamber with a flow rate of no more than 500 seem, no more than 800 seem, or no more than 1000 seem. The plasma may be generated from the ammonia gas inside the deposition chamber. In some embodiments, helium may be introduced to the deposition chamber with a flow rate of no more than 1000 seem, no more than 5000 seem, no more than 10000 seem, no more than 13000 seem, no more than 15000 seem, 18000 seem, or no more than 20000 seem, The plasma may be generated from the helium gas inside the deposition chamber. In some embodiments, argon gas may be introduced to the deposition chamber with a flow rate of no more than 1000 seem, no more than 5000 seem, no more than 10000 seem, no more than 13000 seem, no more than 15000 seem, 18000 seem, or no more than 20000 seem. The plasma may be generated from the argon gas inside the deposition chamber. In some embodiments, nitrogen gas may be introduced to the deposition chamber with a flow rate of no more than 1000 seem, no more than 5000 seem, no more than 10000 seem, no more than 13000 seem, no more than 15000 seem, 18000 seem, no more than 20000 seem, no more than 25000 seem, no more than 27000 seem, or no more than 30000 seem. The plasma may be generated from the helium gas inside the deposition chamber.

[0066] In some embodiments, plasma is generated inside the deposition chamber from one or more gases introduced to the deposition chamber. The ratio of the flow rate of various gases introduced to the chamber may be tuned to control the properties of plasma (e.g., plasma density).Attorney Docket No. 11858-1WO_LAM1P027WO

[0067] In some embodiments, plasma for operation 111 may be generated using various plasma generators. For example, plasma for operation 111 may be generated using a remote plasma generator outside the deposition chamber. In some embodiments, plasma may be generated inside the deposition chamber using a high-frequency or a low-frequency plasma generator. In some embodiments, plasma is generated from a gas using a dual-frequency plasma generator. In some embodiments, for a 4- station chamber, the high-frequency plasma generator may be ignited using a power at least 300W, at least 500W, at least 1000W, or at least 2000 W. In some embodiments, for a 4- station chamber, a high-frequency plasma generator may be ignited using a power no more than about 2800W or no more than 3000W, such as between 300W and 2800W. In some embodiments, for a 4-station chamber, the low- frequency plasma generator may be ignited using a power no more than 1000W, no more than 2000 W, no more than 2700W, or no more than 3000W, such as between 0W and 2700W.

[0068] Plasma generated from different combinations of gases can have different heating efficiencies. Hence, the duration and operating conditions of the plasma heating phase and no-plasma phase may be optimized to ensure proper management of the showerhead temperature.

[0069] The plasma heating operation 103 may be performed at various operating conditions to optimize the showerhead temperature management. Examples of the operating conditions include but are not limited to, duration of operation 103, duration of plasma heating phase, and / or duration of no-plasma phase (i.e., plasma heating frequency or plasma heating interval), selection of plasma generating gas and associated plasma conditions, or duty cycle.

[0070] In various embodiments, the plasma heating operation 103, as described in Figure IB, is performed when no wafer(s) are present within the deposition chamber, i.e., while the deposition chamber is idle. The deposition chamber may be idle for various duration of time. For example, the deposition chamber may be idle for at least 10 minutes, at least 15 minutes, at least 1 hour, at least 8 hours, at least 24 hours, between 1 - 5 days, or more than 5 days.

[0071] In some embodiments, the plasma heating operation 103 may be performed after removing the first substrate from the deposition chamber and prior to introducing a second substrate into the deposition chamber for the second deposition.Attorney Docket No. 11858-1WO_LAM1P027WO

[0072] In some embodiments, the plasma heating operation 103 may be performed for an entire duration of the idle time. Here the entire duration refers to about 100% of the time in which the deposition chamber is idle. For example, the entire duration of the idle time may be at least 90%, at least 95%, at least 98%, or at least 99% of the time the deposition chamber is idle. The entire duration may be about 100% of the time between removing the first substrate after performing the first deposition, i.e., operation 101, and introducing a second substrate to perform operation 105 (i.e., performing the second deposition on the second substrate).

[0073] In some embodiments, the plasma heating operation 103 is performed at least 1 hour before introducing the second substrate into the chamber. In some embodiments, the plasma heating operation 103 is performed at least 30 minutes, at least 2 hours, at least 3 hours, at least 5 hours, at least 12 hours, or at least 24 hours prior to introducing the second substrate into the deposition chamber.

[0074] Returning to operation 111 in Figure IB, the plasma heating phase, may be performed for varying duration of time. In some embodiments, plasma may be introduced to the deposition chamber for about 30 seconds, about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, or about 30 minutes. In some embodiments, plasma may be introduced to the chamber for at least 30 seconds, at least 2 minutes, at least 2.5 minutes, at least 5 minutes, or at least 20 minutes. In some embodiments, operation 111 is performed for a duration between 2 minutes and 20 minutes.

[0075] After operation 111, operation 113 (i.e., no-plasma phase where gas is turned OFF (e.g., RF power is turned off and no plasma is generated)) may be performed. During operation 113, the deposition chamber may be idle. In some embodiments, operation 113 may continue for about 5 minutes, about 10 minutes, about 15 minutes, about 20 minutes, about 30 minutes, or about 1 hour. In some embodiments, operation 113 is performed for at least 5 minutes, at least 10 minutes, at least 20 minutes, at least 30 minutes, or at least 1 hour. In some embodiments, operation 113 is performed for a duration between 5 minutes and 60 minutes.

[0076] In some embodiments, the plasma heating operation 103 includes at least one operation 111 and at least one operation 113. In some embodiments, operations 111 and 113 may be repeated. In some embodiments, operations 111 and 113 are repeated in sequence.Attorney Docket No. 11858-1WO_LAM1P027WOFor example, after performing operation 111, operation 113 may be performed. Subsequent to operation 113, operation 111 may be performed again. In some embodiments, operations 111 and 113 are repeated at least 3 times, at least 5 times, at least 20 times, at least 50 times, or at least 100 times. In various implementations, operations 111 and 113 are repeated for varying number of times, depending on the specifics of operating conditions of operations 111 and 113 (e.g., heating intervals, heating frequency, duration of operation 111).

[0077] In some embodiments, a second substrate is introduced during the operation 113. For example, after repeating operations 111 and 113 one or more times, the second substrate may be introduced to the deposition chamber during the last performed operation 113.

[0078] In some embodiments, operation 111 is performed for 20 minutes, followed by operation 113 performed for 1 hour, and repeating operations 111 and 113 for the entire duration of the idle time. In some embodiments, operation 111 is performed for 20 seconds, followed by operation 113 performed for 5 minutes, and repeating operations 111 and 113 for the entire duration of the idle time. In some embodiments, operation 111 is performed for 5 minutes, followed by operation 113 performed for 5 minutes, and repeating operations 111 and 113 for the entire duration of the idle time. In some embodiments, operation 111 is performed for about 2.5 minutes, followed by operation 113 performed for 5 minutes, and repeating operations 111 and 113 for the entire duration of the idle time. In some embodiments, operation 111 is performed for 10 minutes, followed by operation 113 performed for 1 hour, and repeating operations 111 and 113 for the entire duration of the idle time. In some embodiments, operation 111 is performed for 20 minutes, followed by operation 113performed for 30 minutes, and repeating operations 111 and 113 for the entire duration of the idle time. In some embodiments, operation 111 is performed for about 15 minutes, followed by operation 113performed for 30 minutes, and repeating operations 111 and 113 for the entire duration of the idle time. In some embodiments, operation 111 is performed for 30 minutes, followed by operation 113 performed for 2 hours, and repeating operations 111 and 113 for the entire duration of the idle time.

[0079] In some embodiments, each of operation 111 during repeated operation 103 (i.e., repeating operations 111 and 113) is performed for the same duration of time. In some embodiments, each of operation 113 during repeated operation 103 is performed for the same duration of time.Attorney Docket No. 11858-1WO_LAM1P027WO

[0080] In some embodiments, the plasma heating operation 103 may adopt a sequential or variable heating schedule. In some embodiments, plasm heating operation 103 can involve one or more plasma heating phase schedules and one or more no-plasma phase schedules. For example, the deposition chamber is idle for at least 2 hours, after performing the first deposition and removing the first substrate (i.e., operation 101) and up to 1 hour prior to the second deposition on a second substrate (i.e., operation 105), a first schedule may be used to perform operation 103. After performing operation 103 under the first schedule, a second schedule may be adapted to perform operation 103 for the last 1 hour prior to operation 105. An example of the first and second schedules may be where the first schedule involves performing operation 111 for 15 minutes followed by performing operation 113 for 1 hour, and the first schedule is repeated until the last 1 hour prior to operation 104. The second schedule may involve performing operation 111 for 5 minutes, followed by performing operation 113 for 10 minutes and repeating the second schedule for the remaining 1-hour duration prior to the beginning of operation 105.

[0081] In some embodiments, operation 103 is performed at least for the last 50% of the deposition chamber idle time. In some cases, operation 103 is performed for the entire duration of the deposition chamber idle time. In some embodiments, operation 103 may be performed at least for the last 75%, at least for the last 30%, or at least for the last 25% of the deposition chamber idle time.

[0082] In various operating conditions, the plasma heating frequency, schedule, timing, and other aspects of the plasma heating are optimized depending on the state and / or history of the deposition chamber. This is because, as described elsewhere herein, the showerhead temperature may be different depending on the preceding events of the deposition chamber leading to the plasma heating operation.

[0083] In some embodiments, when the showerhead is considered to have reached a stable temperature, the rate of change in the deposition rate over the deposition process is at or near zero. For example, a showerhead that has reached a stable temperature may exhibit a deposition rate of about 2200 ± 25A / minute over the 7-deposition process. In some embodiments, the deposition rate of the showerhead(s) with stable temperature may vary no more than ± 50 A / minute, no more than ± 30 A / minute, no more than ± 15 A / minute, or no more than ± 5 A / minute.Attorney Docket No. 11858-1WO_LAM1P027WO

[0084] In some embodiments, when the showerhead is considered to have reached a stable temperature, the change in film properties, such as stress or nonuniformity % over the deposition processes, are at or near zero. For example, a showerhead that has reached a stable temperature may produce films having stress values of about -475 ± 50MPa over several deposition processes. In some cases, the stress values of the thin films deposited using a showerhead with stable temperature vary no more than ± 40MPa, no more than ± 30MPa, or no more than ± 25MPa. In another example, a showerhead that has reached a stable temperature may produce films that are conformal, with a nonuniformity % of about 11.5 ±1% over several deposition processes. In some cases, the nonuniformity of the resulting films deposited using a showerhead with stable temperature varies no more than 2%, no more than 0.75%, no more than 0.5%, or no more than 0.2%.

[0085] In some embodiments, the rate of change in deposition rate or film properties over the deposition processes may be controlled by the heating ‘duty cycle’. The duty cycle here refers to a ratio of the duration of the plasma heating phase (i.e., duration of each operation 111) to the combined duration of the plasma heating phase and no-plasma phase (i.e., duration of operation 111 added to the duration of operation 113) in operation 103 without considering repeated operations 111 and 113 in operation 103. For example, the duty cycle for a 20-minute plasma heating phase and a 60-minute no-plasma phase is 25%. In various implementations, operation 103 has a duty cycle for operation 103 is no more than 50%. In some embodiments, operation 103 has a duty cycle between 30% and 35%. In some embodiments, operations 103 has a duty cycle between 25% and 40%. In some embodiments, operation 103, with a duty cycle between about 33% and 35%, may have stable showerhead temperature with minimal change in deposition rate over several deposition processes.

[0086] In some embodiments, the frequency of the plasma heating phase may be optimized to reduce the duration of the no-plasma phase to reduce variation in showerhead temperatures between each plasma heating phase. This may be useful for reducing showerhead temperature variation where the substrate is introduced to the deposition chamber during the non-plasma phase.

[0087] In some embodiments, other operating conditions of the plasma heating operation may also be tuned. For example, operation 103 may be performed at different temperatures and pressures. In some embodiments, during the operation 103, the temperature of theAttorney Docket No. 11858-1WO_LAM1P027WO deposition chamber may be at least about 100°C, at least 125°C, at least 140°C, at least 150°C, at least 250°C, or at least 350°C. In some embodiments, the temperature of the deposition during operation 103 may be about 400°C or no more than 400°C. In some embodiments, the deposition chamber during operation 103 may be between 140°C and 400°C. In some embodiments, operation 103 may be performed where the deposition chamber pressure is at least 1 Torr, at least 2 Torr, at least 4 Torr, or about 5 Torr. In some embodiments, operation 103 is performed in the deposition chamber having pressure no more than 5 Torr, such as between 2 Torr and 5 Torr.

[0088] In some embodiments, incorporating the plasma heating operation 103 while the deposition chamber is idle can improve wafer-to-wafer thickness and reduce wafer-to-wafer non-uniformity. When practiced, method 100 can reduce variation between the first deposition rate and the second deposition rate. In some embodiments, the plasma heating, according to various embodiments described above, may reduce variation in the wafer-to- wafer thickness nonuniformity across wafers between the first deposition and the second deposition. For example, the thickness nonuniformity of the second deposition may be at least 10%, at least 2%, at least 5%, at least 15%, or at least 25% lower than the first deposition.

[0089] Figure 2 compares experimental results illustrating the effects of performing method 100 in accordance with the disclosed embodiments. Figure 2 compares various film or deposition properties (deposition rate, stress, and nonuniformity %) when method 100 is performed (in solid line) and when method 100 is not performed (in dotted line). As depicted in Figure 2, deposition rate, stress, and wafer-to-wafer nonuniformity % across several deposition processes can vary significantly when method 100 is not performed. In contrast, when practiced, variations in deposition rate, stress, and wafer-to-wafer nonuniformity % across several deposition processes are substantially reduced. For example, without practicing method 100, the deposition rate can range from about 1800A / minute and 2150A / minute. When method 100 is performed, this variation is significantly reduced. In another example, without practicing method 100, the stress value can range from about - 625MPa to about -450MPa. In contrast, when method 100 is performed, the stress value may be substantially reduced, e.g., ranging from about -575MPa to about -500MPa. In some embodiments, without practicing method 100, the wafer-to-wafer nonuniformity in thickness may range from about 7% and about 12% across different depositions. In contrast,Attorney Docket No. 11858-1WO_LAM1P027WO when method 100 is practiced, the wafer-to-wafer nonuniformity in thickness is substantially improved. For example, wafer-to-wafer nonuniformity in thickness may improve from about 16.5% without practicing method 100 to about 2% when method 100 is practiced.

[0090] In some embodiments, when repeating operations 111 and 113, where operation 111 is performed for about 20 minutes, followed by operation 113, which is performed for 1 hour, wafer-to-wafer nonuniformity in thickness is improved from 20% without performing method 100 to about 4.5% when method 100 is performed. In some embodiments, method 100 improved wafer-to-wafer nonuniformity in thickness from about 16.5% without performing method 100 to about 2% with performing method 100 with a duty cycle of about 35%.

[0091] Returning to Figure 1A, after performing operation 103, operation 105 may optionally be performed, during which a second substrate is introduced to the deposition chamber, and the second deposition is performed on the second substrate. In some embodiments, the first and second substrates may be the same or different, and the first and second depositions may be the same or different. In some embodiments, the deposition chamber may be cleaned between the first and second deposition processes, prior to introducing a second substrate.Apparatus

[0092] Figure 3 depicts a schematic illustration of an embodiment of a deposition station 300 having a deposition chamber body 302. A plurality of deposition station 300 may be included in a common low-pressure process tool environment. For example, Figure 4 depicts an embodiment of a multi-station processing tool 400. In some embodiments, one or more hardware parameters of deposition station 300, including those discussed in detail below, may be adjusted programmatically by one or more computer controllers 350.

[0093] Deposition station 300 fluidly communicates with reactant delivery system 301 for delivering process gases to a distribution showerhead 306. Reactant delivery system 301 includes a mixing vessel 304 for blending and / or conditioning process gases for delivery to showerhead 306. One or more mixing vessel inlet valves 320 may control the introduction of process gases to mixing vessel 304.Attorney Docket No. 11858-1WO_LAM1P027WO

[0094] As an example, the embodiment of Figure 3 includes a vaporization point 303 for vaporizing liquid reactant to be supplied to the mixing vessel 304. In some embodiments, vaporization point 303 may be a heated vaporizer. The saturated reactant vapor produced from such vaporizer may condense in downstream delivery piping. Exposure of incompatible gases to the condensed reactant may create small particles. These small particles may clog piping, impede vale operation, contaminate substrates, etc. Some approaches to addressing these issues involve purging and / or evacuating the delivery piping to remove residual reactant. However, purging the delivery piping may increase deposition station cycle time, degrading deposition station throughput. Thus, in some embodiments, delivery piping downstream of vaporization point 303 may be heat traced. In some examples, mixing vessel 304 may also be heat traced. In one non-limiting example, piping downstream of vaporization point 303 has an increasing temperature profile extending from approximately 100°C to approximately 150°C at mixing vessel 304.

[0095] In some embodiments, liquid precursor or liquid reactant may be vaporized at a liquid injector. For example, a liquid injector may inject pulses of a liquid reactant into a carrier gas stream upstream of the mixing vessel. In some embodiments, a liquid injector may vaporize the reactant by flashing the liquid from a higher pressure to a lower pressure. In another example, a liquid injector may atomize the liquid into dispersed microdroplets that are subsequently vaporized in a heated delivery pipe. Smaller droplets may vaporize faster than larger droplets, reducing the delay between liquid injection and complete vaporization. Faster vaporization may reduce the length of piping downstream from vaporization point 303. In one scenario, a liquid injector may be mounted directly to mixing vessel 304. In another scenario, a liquid injector may be mounted directly to showerhead 306.

[0096] In some embodiments, a liquid flow controller (LFC) upstream of vaporization point 303 may be provided for controlling a mass flow of liquid for vaporization and delivery to deposition station 300. For example, the LFC may include a thermal mass flow meter (MFM) located downstream of the LFC. A plunger valve of the LFC may then be adjusted responsive to feedback control signals provided by a proportional-integral-derivative (PID) controller in electrical communication with the MFM. However, it may take one second or more to stabilize liquid flow using feedback control. This may extend the time for dosing a liquid reactant. Thus, in some embodiments, the LFC may be dynamically switched betweenAttorney Docket No. 11858-1WO_LAM1P027WO a feedback control mode and a direct control mode. In some embodiments, this may be performed by disabling a sense tube of the LFC and the PID controller.

[0097] Showerhead 306 distributes process gases toward substrate 312. In the embodiment shown in Figure 3, the substrate 312 is located beneath showerhead 306 and is shown resting on a pedestal 308. Showerhead 306 may have any suitable shape and may have any suitable number and arrangement of ports for distributing process gases to substrate 312. Example process gases include soak gases, precursor gases, carrier gases or purge cases.

[0098] In some embodiments, a microvolume 307 is located beneath showerhead 306. Practicing disclosed embodiments in a microvolume rather than in the entire volume of the deposition station may reduce reactant exposure and purge times and may reduce times for altering process conditions (e.g., pressure, temperature, etc.) may limit an exposure of process station robotics to process gases, etc. example microvolume sizes include, but are not limited to, volumes between 0.1 liter and 2 liters. This also impacts productivity throughput. In some embodiments, the disclosed embodiments are not performed in a micro volume.

[0099] In some embodiments, pedestal 308 may be raised or lowered to expose substrate 312 to microvolume 307 and / or to vary the volume of microvolume 307. For example, in a substrate transfer phase, pedestal 308 may be raised to position substrate 312 within microvolume 307. In some embodiments, microvolume 307 may completely enclose substrate 312 as well as a portion of pedestal 308 to create a region of high flow impedance.

[0100] Optionally, pedestal 308 may be lowered and / or raised during portions of the process to modulate process pressure, reactant concentrations, etc., within microvolume 307. In one scenario where deposition chamber body 302 remains at a base pressure during the process, lowering pedestal 308 may allow microvolume 307 to be evacuated. Example ratios of microvolume to deposition chamber volume include, but are not limited to, volume ratios between 1:500 and 1:10. It will be appreciated that, in some embodiments, pedestal height may be adjusted programmatically by a suitable computer controller 350.

[0101] In another scenario, adjusting the height of pedestal 308 may allow a plasma density to be varied during plasma activation and / or treatment cycles included in the process, for example, a plasma heating of the showerhead to manage the temperature of the showerhead.Attorney Docket No. 11858-1WO_LAM1P027WOAt the conclusion of the process phase, pedestal 308 may be lowered during another substrate transfer phase to allow removal of substrate 312 from pedestal 308.

[0102] While the example microvolume variations described herein refer to a height- adjustable pedestal, it will be appreciated that, in some embodiments, a position of showerhead 306 may be adjusted relative to pedestal 308 to vary a volume of microvolume 307. Further, it will be appreciated that a vertical position of pedestal 308 and / or showerhead 306 may be varied by any suitable mechanism within the scope of the present disclosure. In some embodiments, pedestal 308 may include a rotational axis for rotating an orientation of substrate 312. It will be appreciated that, in some embodiments, one or more of these example adjustments may be performed programmatically by one or more suitable computer controllers 350.

[0103] In some embodiments where plasma may be used as discussed above, a showerhead 306 and pedestal 308 electrically communicate with a radio frequency (RF) power supply 314 and matching network 316 for powering a plasma. In some embodiments, the plasma energy may be controlled by controlling one or more of a process station pressure, a gas concentration, an RF source power, an RF source frequency, and a plasma power pulse timing. For example, RF power supply 314 and matching network 316 may be operated at any suitable power to form a plasma having a desired composition of radical species. Examples of suitable powers are included above. Likewise, RF power supply 314 may provide RF power to any suitable frequency. In some embodiments, RF power supply 314 may provide RF power of any suitable frequency. In some embodiments, RF power supply 314 may provide RF power of any suitable frequency. In some embodiments, RF power supply 314 may be configured to control high-and low-frequency power sources independently of one another. Example low-frequency RF frequencies may include, but are not limited to, frequencies between 50 kHz and 500 kHz. Examples of high-frequency RF frequencies may include, but are not limited to, frequencies between 1.8 MHz and 2.5 GHz, for example, 2 MHz, 13.5 MHz, or 27 MHz. it will be appreciated that any suitable parameters may be modulated discretely or continuously to provide plasma energy for the surface reactions. In one non-limiting example, the plasma power may be intermittently pulsed o reduce ion bombardment with the substrate surface relative to continuously powered plasmas.Attorney Docket No. 11858-1WO_LAM1P027WO

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

[0105] In some embodiments, instructions for a controller 350 may be provided via input / output control (IOC) sequencing instructions. In one example, the instructions for setting conditions for a process phase may be included in a corresponding recipe phase of a process recipe. In some cases, process recipe phases may be sequentially arranged, so that all instructions for a process phase are executed concurrently with that process phase. In some embodiments, instructions for a process phase are executed concurrently with that process phase. In some embodiments, instructions for setting one or more reactor parameters may be included in a recipe phase. For example, a first recipe phase may include instructions for setting a flow rate of inert and / or reactant gases (e.g., the second reactant), instructions for setting a flow rate of a carrier gas (such as nitrogen), instructions for setting a pedestal temperature, and time delay instructions for the first recipe phase. A second, subsequent recipe phase may include instructions for modulating or stopping a flow rate of an inert and / or reactant gas, and instructions for modulating a flow rate of a carrier or purge gas and time delay instructions for the second recipe phase. A third recipe phase may include instructions for setting a flow rate of an inert and / or reactant gas (e.g., the first precursor), instructions for modulating a flow rate of a carrier gas, and time delay instructions for the third recipe phase. A fourth recipe phase may include instructions for modulating or stopping a flow rate of an inert and / or a reactant gas, instructions for modulating the flow rate of a carrier or purge gas, and time delay instructions for the fourth recipe phase. A fifth recipe phase may include instructions for modulating or stopping a flow rate of an inert and / or a reactant gas which may be the same or different from the gas used in the first recipe phase (e.g., the second reactant), instructions for modulating the flow rate of a carrier or purge gas, and time delay instructions for the fifth recipe phase. It will be appreciated that these recipeAttorney Docket No. 11858-1WO_LAM1P027WO phases may be further subdivided and / or iterated in any suitable way within the scope of the present disclosure.

[0106] In some embodiments, pedestal 308 may be temperature-controlled via heater 310. The pedestal may be set to a deposition temperature. For example, the pedestal may be set to a temperature between about 200°C and about 300°C for deposition of a nitride or carbide. Further, in some embodiments, pressure control for process station 300 may be provided by butterfly valve 318. As shown in the embodiment of Figure 3, butterfly valve 318 throttles a vacuum provided by a downstream vacuum pump (not shown). However, in some embodiments, pressure control of process station 300 may also be adjusted by varying a flow rate of one or more gases introduced to the process station 300.

[0107] As described above, one or more process stations may be included in a multi- station processing tool. Figure 4 shows a schematic view of an embodiment of a multi-station processing tool 400 with an inbound load lock 402 and an outbound loadlock 404, either or both of which may comprise a remote plasma source. A robot 406, at atmospheric pressure, is configured to move substrates or wafers from cassette loaded through a pod 408 into inbound loadlock 402 via an atmospheric port 410. A substrate is placed by the robot 406 on a pedestal 412 in the inbound loadlock 402, the atmospheric port 410 is closed, and the loadlock is pumped down. Where the inbound loadlock 402 comprises a remote plasma source, the substrate may be exposed to a remote plasma treatment in the loadlock prior to being introduced into a processing chamber 414. Further, the substrate also may be heated in the inbound loadlock 402 as well, for example, to remove moisture and adsorbed gases. Next, a chamber transport port 416 to the processing chamber 414 is opened, and another robot (not shown) places the substrate into the reactor on a pedestal of the first station shown in the reactor for the process. While the embodiment depicted in Figure 4 includes loadlocks, it will be appreciated that, in some embodiments, direct entry of a substrate into a process station may be provided.

[0108] The depicted processing chamber 414 comprises four process stations, numbered from 1 to 4 in the embodiment shown in Figure 4. Each station has a heated pedestal (shown at 418 for station 1), and gas line inlets. It will be appreciated that in some embodiments, each process station may have different or multiple purposes. For example, in some embodiments, a process station may be switchable between an ALD and plasma-enhanced ALD process mode. Additionally or alternatively, in some embodiments, processingAttorney Docket No. 11858-1WO_LAM1P027WO chamber 414 may include one or more matched pairs of ALD and plasma-enhanced ALD process stations. While the depicted processing chamber 414 includes four stations, it will be understood that a processing chamber according to the present disclosure may have any suitable number of stations. For example, in some embodiments, a processing chamber may have five or more stations, while in other embodiments a processing chamber may have three or fewer stations.

[0109] Figure 4 shows a schematic diagram of an example plasma processing apparatus configured to perform PECVD according to some implementations. The plasma processing apparatus may be configured to deposit a compressive nitride film by PECVD according to the techniques described in the present disclosure.

[0110] As shown in Figure 4, a plasma processing apparatus 400 includes a process chamber 424, which encloses other components of the plasma processing apparatus 400 and serves to contain a plasma. The process chamber 424 includes a showerhead 414 for delivering process gases into the process chamber 424. The process chamber 424 may be configured as a dual-frequency plasma source. A high-frequency radio -frequency (HFRF) generator 402 may be connected to an impedance matching network 406, which is connected to the showerhead 414. In some implementations, a low-frequency radio-frequency (LFRF) generator 404 may be connected to the impedance matching network 406 to connect to the showerhead 414. The power and frequency supplied by the impedance matching network 406 is sufficient to generate a plasma from process gas. In typical processes, a frequency generated by the HFRF generator 402 is between 2-60 MHz, such as 13.5 MHz or 27 MHz. A frequency generated by the LFRF generator 404 is between about 250-400 kHz, such as 350 kHz or 400 kHz. In some embodiments, the showerhead 414 and a pedestal 418 may electrically communicate with the HFRF generator 402, LFRF generator 404, and impedance matching network 406 for powering a plasma. In some embodiments, the plasma energy may be controlled by controlling one or more of a process chamber pressure, gas concentrations and partial pressures of gases or gas flow rates, plasma power and frequency to the HFRF generator 402, plasma power and frequency to the LFRF generator 404. In some embodiments, the HFRF generator 402 and the LFRF generator 404 may be controlled independently of one another. It will be appreciated that any suitable parameters may be modulated discretely or continuously to provide plasma energy for a reaction for depositing compressive nitride layer.

[0111] In some embodiments, the plasma may be monitored in-situ by one or more plasmaAttorney Docket No. 11858-1WO_LAM1P027WO monitors. In one scenario, plasma power may be monitored by one or more voltage, current sensors (e.g., VI probes). In another scenario, plasma density and / or process gas concentration may be measured by one or more optical emission spectroscopy sensors (OES). In some embodiments, one or more plasma parameters may be programmatically adjusted based on measurements from such in-situ plasma monitors. For example, an OES sensor may be used in a feedback loop for providing programmatic control of plasma power. It will be appreciated that, in some embodiments, other monitors may be used to monitor the plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure transducers.

[0112] The process chamber 424 further includes a wafer support or pedestal 418. The pedestal 418 may support a wafer 416. In some embodiments, the pedestal 418 can include a chuck, a fork, and / or lift pins to hold the wafer 416 during and between processing. In some implementations, the pedestal 418 is an electrostatic chuck. In some implementations, the pedestal 418 includes wafer holders to hold the wafer 416 by the edges so that a bottom showerhead (not shown) may deliver gases to a backside of the wafer 416.

[0113] In some embodiments, pedestal 418 may be temperature controlled via one or more heating elements (not shown). In some cases, the one or more heating units may be used to anneal the wafer 416. For example, in some embodiments, the one or more heating elements may maintain the wafer 416 at a temperature less than about 650°C during deposition, or between about 100°C and about 450°C during deposition of a compressive nitride film of the present disclosure. The one or more heating elements may heat the wafer 416 to temperatures equal to or greater than about 650°C in subsequent operations such as annealing.

[0114] Process gases may be introduced via inlet 412. One or more source gas lines 410 can be connected to a manifold 408. The process gases may be premixed or not. Appropriate valving and mass flow control mechanisms are employed to ensure that the correct gases are delivered during deposition and other processing operations. Process gases may exit the process chamber 424 via an outlet 422. A vacuum pump 426 can typically draw process gases out and maintain a suitably low pressure within the process chamber 424.

[0115] Though the showerhead 414 for delivery of process gases may appear oriented as a top showerhead, it will be understood that the showerhead 414 may be configured as aAttorney Docket No. 11858-1WO_LAM1P027WO bottom showerhead or showerhead pedestal (“shoped”) for delivery of process gases to the backside of the wafer 416. Thus, a faceplate of the showerhead 414 may be configured to face the backside of the wafer 416 such as the backside of a bowed semiconductor substrate. For example, the showerhead 414 may distribute process gases for depositing a bow compensation layer such as a silicon nitride layer on the backside of the wafer 416, where the process gases may include a silicon-containing precursor, a nitrogen-containing reactant, and / or inert gas. The showerhead 414 may have any suitable shape, and may have any suitable number and arrangement of ports for distributing process gases to the wafer 416. A shield (not shown) may also be present in the process chamber 424.

[0116] As shown in Figure 4, the plasma processing apparatus 400 is a capacitor-type system where the showerhead 414 is an electrode working in conjunction with a grounded block 420. In other words, the plasma processing apparatus 400 is a capacitively-coupled plasma (CCP) system and may be capable of supplying high-frequency RF power to the top of the process chamber 424, namely the showerhead 414. The bottom of the process chamber 424, namely the pedestal 418 and the block 420, may be grounded.

[0117] One of the apparatuses for performing deposition, such as the plasma processing apparatus 400, may be implemented in a multi-station processing tool. An example multistation processing tool is described below.

[0118] Figure 5 depicts an embodiment of a wafer handling system 590 for transferring substrates within processing chamber 514. In some embodiments, wafer handling system 590 may transfer substrates between various process stations and / or between a process station and a load lock. It will be appreciated that any suitable wafer handling system may be employed. Non-limiting examples include wafer carousels and wafer handling robots. Figure 5 also depicts an embodiment of a system controller 550 employed to control process conditions and hardware states of process tool 500. System controller 550 may include one or more memory devices 556, one or more mass storage devices 554, and one or more processors 552. Processor 552 may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc.

[0119] In some embodiments, system controller 550 controls all of the activities of process tool 500. System controller 550 executes system control software 558 stored in mass storage device 554, loaded into memory device 556, and executed on processor 552. Alternatively, the control logic may be hard coded in the controller 550. ApplicationsAttorney Docket No. 11858-1WO_LAM1P027WOSpecific Integrated Circuits, Programmable Logic Devices (e.g., field-programmable gate arrays, or FPGAs) and the like may be used for these purposes. In the following discussion, wherever “software” or “code” is used, functionally comparable hard coded logic may be used in its place. System control software 458 may include instructions for controlling the timing, mixture of gases, amount of gas flow, chamber and / or station pressure, chamber and / or station temperature, substrate temperature, target power levels, RF power levels, substrate pedestal, chuck and / or susceptor position, and other parameters of a particular process performed by process tool 500. System control software 558 may be configured in any suitable way. For example, various process tool component subroutines or control objects may be written to control operation of the process tool components used to carry out various process tool processes. System control software 558 may be coded in any suitable computer readable programming language.

[0120] In some embodiments, system control software 558 may include input / output control (IOC) sequencing instructions for controlling the various parameters described above. Other computer software and / or programs stored on mass storage device 554 and / or memory device 556 associated with system controller 550 may be employed in some embodiments. Examples of programs or sections of programs for this purpose include a substrate positioning program, a process gas control program, a pressure control program, a heater control program, and a plasma control program.

[0121] A substrate positioning program may include program code for process tool components that are used to load the substrate onto pedestal 518 and to control the spacing between the substrate and other parts of process tool 500.

[0122] A process gas control program may include code for controlling gas composition (e.g., first precursor gas, soak gas, second reactant gas, and purge gases as described herein) and flow rates and optionally for flowing gas into one or more process stations prior to deposition in order to stabilize the pressure in the process station. A pressure control program may include code for controlling the pressure in the process station by regulating, for example, a throttle valve in the exhaust system of the process station, a gas flow into the process station, etc.

[0123] A heater control program may include code for controlling the current to a heating unit that is used to heat the substrate. Alternatively, the heater control program may control delivery of a heat transfer gas (such as the soak gas) to the substrate.Attorney Docket No. 11858-1WO_LAM1P027WO

[0124] A plasma control program may include code for setting RF power levels applied to the process electrodes in one or more process stations in accordance with the embodiments herein.

[0125] A pressure control program may include code for maintaining the pressure in the reaction chamber in accordance with the embodiments herein.

[0126] In some embodiments, there may be a user interface associated with system controller 550. The user interface may include a display screen, graphical software displays of the apparatus and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0127] In some embodiments, parameters adjusted by system controller 550 may relate to process conditions. Non-limiting examples include process gas composition and flow rates, temperature, pressure, plasma conditions (such as RF bias power levels), pressure, temperature, etc. These parameters may be provided to the user in the form of a recipe, which may be entered utilizing the user interface.

[0128] Signals for monitoring the process may be provided by analog and / or digital input connections of system controller 550 from various process tool sensors. The signals for controlling the process may be output on the analog and digital output connections of process tool 500. Non-limiting examples of process tool sensors that may be monitored include mass flow controllers, pressure sensors (such as manometers), thermocouples, etc. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain process conditions.

[0129] System controller 550 may provide program instructions for implementing the above-described deposition processes such as processes that employ a soak prior to initiating ALD for a substrate inserted into the reaction chamber, with the soak performed under any of the soak conditions described herein. The program instructions may control a variety of process parameters, such as DC power level, RF bias power level, pressure, temperature, etc. The instructions may control the parameters to operate in-situ deposition of film stacks according to various embodiments described herein.

[0130] The system controller will typically include one or more memory devices and one or more processors configured to execute the instructions so that the apparatus will perform a method in accordance with disclosed embodiments. Machine-readable media containingAttorney Docket No. 11858-1WO_LAM1P027WO instructions for controlling process operations in accordance with disclosed embodiments may be coupled to the system controller.

[0131] In some implementations, the system controller 550 is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The system controller 550, depending on the processing conditions and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0132] Broadly speaking, the system controller 550 may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the system controller 550 in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0133] The system controller 550, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the system controller 550 may be in theAttorney Docket No. 11858-1WO_LAM1P027WO“cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the system controller 550 receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the system controller 550 is configured to interface with or control. Thus as described above, the system controller 550 may be distributed, such as by including one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0134] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0135] As noted above, depending on the process step or steps to be performed by the tool, the system controller 550 might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locationsAttorney Docket No. 11858-1WO_LAM1P027WO and / or load ports in a semiconductor manufacturing factory.

[0136] The apparatus / process described herein may be used in conjunction with lithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, photovoltaic panels and the like. Typically, though not necessarily, such tools / processes will be used or conducted together in a common fabrication facility. Lithographic patterning of a film typically includes some or all of the following operations, each operation enabled with a number of possible tools: (1) application of photoresist on a workpiece, i.e., substrate, using a spin-on or spray-on tool;(2) curing of photoresist using a hot plate or furnace or UV curing tool; (3) exposing the photoresist to visible or UV or x-ray light with a tool such as a wafer stepper; (4) developing the resist so as to selectively remove resist and thereby pattern it using a tool such as a wet bench; (5) transferring the resist pattern into an underlying fdm or workpiece by using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

Claims

Attorney Docket No. 11858-1WO_LAM1P027WOCLAIMSWhat is claimed is:

1. A method of maintaining a deposition chamber, the method comprising: after performing a first deposition on a first substrate, removing the first substrate from the deposition chamber housing the first substrate; after removing the first substrate from the deposition chamber, performing a plasma heating, wherein the plasma heating comprises: a plasma heating phase during which the deposition chamber is exposed to a plasma generated from a gas to heat a showerhead; and a no-plasma phase during which no plasma is generated in the deposition chamber, wherein the plasma heating stabilizes the temperature of the showerhead.

2. The method of claim 1, the method further comprising: repeating the plasma heating phase and the no-plasma phase.

3. The method of claim 1, the method further comprising: performing a second deposition on a second substrate, wherein the plasma heating is performed after removing the first substrate from the deposition chamber and prior to introducing the second substrate into the deposition chamber for the second deposition.

4. The method of claim 3, wherein the plasma heating is performed for an entire duration after removing the first substrate from the deposition chamber and prior to the second deposition.

5. The method of claim 3, wherein the plasma heating reduces variation between a first deposition rate for the first deposition and a second deposition rate for the second deposition.Attorney Docket No. 11858-1WO_LAM1P027WO6. The method of claim 3, wherein the plasma heating reduces variation in the stress between the first deposition and the second deposition.

7. The method of claim 3, wherein the plasma heating reduces variation in the wafer-to- wafer thickness non-uniformity across wafers between the first deposition and the second deposition.

8. The method of claim 3, wherein a thickness non-uniformity of the second deposition is at least 10% lower than the first deposition.

9. The method of claim 1, wherein the plasma heating phase is performed for at least 2 minutes.

10. The method of claim 1, wherein the plasma heating phase is performed for a duration between 2 minutes and 20 minutes.

11. The method of claim 1, wherein the no plasma phase is performed for at least 5 minutes.

12. The method of claim 1, wherein the no plasma phase is performed for a duration between 5 minutes and 60 minutes.

13. The method of claim 1, wherein the plasma heating phase and the no-plasma phase are repeated two or more times.

14. The method of claim 13, wherein each of the plasma heating phases is performed for the same duration of time.

15. The method of claim 13, wherein each of the no-plasma phases lasts for the same duration of time.

16. The method of claim 1, wherein the plasma heating has a duty cycle between 25% and 40%.Attorney Docket No. 11858-1WO_LAM1P027WO17. The method of claim 1, wherein the deposition chamber has a pedestal temperature between 140°C and 400 °C during the plasma heating.

18. The method of claim 1, wherein the deposition chamber has a pressure between 2 Torr and 5 Torr during the plasma heating.

19. The method of claim 1, wherein the gas from which the plasma is generated in a remote plasma generator.

20. The method of claim 1, wherein the plasma is generated from the gas using a high- frequency plasma generator.

21. The method of claim 20, wherein the high-frequency plasma generator is ignited using 300 - 2800 W of power.

22. The method of claim 1, wherein the plasma is generated from the gas using a low- frequency plasma generator.

23. The method of claim 22, wherein the low-frequency plasma generator is ignited using no more than 2700 W of power.

24. The method of claim 1, wherein the plasma is generated from the gas using a dualfrequency plasma generator.

25. The method as in one of claims 21-24, wherein the gas is selected from the group consisting of nitrous oxide (N2O), carbon dioxide (CO2), ammonia (NH3), hydrogen (H2), nitrogen (N2), helium, argon, and combinations thereof.

26. The method of claim 25, wherein a flow rate of N2O introduced to the deposition chamber is between 2000 seem and 18000 seem.

27. The method of claim 25, wherein a flow rate of NH3 introduced to the deposition chamber is no more than 800 seem.Attorney Docket No. 11858-1WO_LAM1P027WO28. The method of claim 25, wherein a flow rate of helium introduced to the deposition chamber is no more than 18000 seem.

29. The method of claim 25, wherein a flow rate of N2 introduced to the deposition chamber is no more than 18000 seem.

30. The method of claim 25, wherein a flow rate of Ar introduced to the deposition chamber is no more than 18000 seem.

31. The method as in one of claims 22-27, wherein the gas comprises nitrous oxide (N2O).

Images