Chemical sensors for automatic flow correction in mass flow controllers

Abstract

An example of automatic flow correction of a reaction gas based on the detected concentration of a second gas flowing with the reaction gas is disclosed. In one example, a substrate processing tool is provided, comprising a processing chamber. The substrate processing tool further comprises a conduit for flowing a mixture of the reaction gas and the second gas into the processing chamber. The substrate processing tool further comprises a chemical sensor configured to detect the concentration of the second gas in the conduit. The substrate processing tool further comprises a mass flow controller positioned downstream from each sensor along the conduit. The substrate processing tool further comprises a system controller configured to receive a signal from the chemical sensor indicating the concentration of the second gas in the conduit and to adjust the mass flow controller based on that signal and a setpoint of the reaction gas.

Description

Background Art

[0001] Semiconductor device manufacturing processes include numerous steps such as material deposition, patterning, and removal to form integrated circuits on a substrate. Various methods can be used to deposit a film of material on a substrate. As an example, chemical vapor deposition (CVD) forms a film by directing a continuous flow of reaction gas over the substrate under conditions set to convert the reaction gas into the film. In various examples, the reaction gas can be converted into the film using heat (thermal CVD) or plasma (plasma-enhanced CVD). In some examples, film deposition can be affected by the flow rate of the reaction gas flowing into the processing chamber.

Summary of the Invention

[0002] This section is provided to introduce selected concepts in a simplified form that are further described in the Detailed Description of the Embodiments below. This section is not intended to identify key features or essential features of the subject matter of the present application, nor is it intended to be used to limit the scope of the subject matter of the present application. Furthermore, the subject matter of the present application is not limited to embodiments that solve any or all disadvantages described in any part of the present disclosure.

[0003] Examples related to automatic flow correction of a reaction gas based on a detected concentration of a second gas flowing together with the reaction gas are disclosed. In one example, a substrate processing tool is provided. The substrate processing tool includes a processing chamber. The substrate processing tool further includes a conduit for flowing a mixture of a reaction gas and a second gas into the processing chamber. The substrate processing tool further includes a chemical sensor configured to detect the concentration of the second gas in the conduit. The substrate processing tool further includes a mass flow controller disposed downstream from the chemical sensor along the conduit. The substrate processing tool further includes a system controller configured to receive a signal indicative of the concentration of the second gas in the conduit from the chemical sensor. The system controller is further configured to adjust the mass flow controller based on the signal and a set point of the reaction gas.

[0004] In some such cases, the reaction gas contains acetylene.

[0005] In some such cases, the second gas contains an additional or alternative stabilizer.

[0006] In some such cases, the stabilizer includes acetone, either additionally or as an alternative.

[0007] In some such examples, chemical sensors include, either additionally or alternatively, infrared sensors.

[0008] In some such examples, chemical sensors include, either additionally or alternatively, visible light sensors.

[0009] In some such examples, the system controller is configured to adjust the flow offset of the mass flow controller using a lookup table, either additionally or alternatively.

[0010] In some such examples, the substrate processing tool is configured, either additionally or alternatively, to form a plasma using a reactive gas to deposit the film.

[0011] Another example provides a method for controlling a substrate processing tool. This method involves using a mass flow controller to control the flow of a reaction gas and a second gas through a conduit to the processing chamber of the substrate processing tool. This method further includes using a chemical sensor located along the conduit to detect the concentration of the second gas flowing through the conduit. The chemical sensor is located upstream of the mass flow controller. This method further includes adjusting the mass flow controller at least based on the detected concentration of the second gas.

[0012] In some such examples, detecting the concentration of a second gas involves using an infrared sensor.

[0013] In some such examples, adjusting the mass flow controller may, in addition or alternatively, include adjusting the flow offset of the mass flow controller.

[0014] In some such examples, adjusting the mass flow controller may additionally or alternatively involve using lookup tables.

[0015] In some such cases, adjusting the flow rate of the gas mixture is additionally or alternatively based on the target deposition rate.

[0016] In some such examples, the reaction gas includes an additional or alternative carbon-containing gas, and the method further includes depositing a carbon-based film on a substrate placed in a processing chamber.

[0017] In some such examples, the carbon-containing gas contains acetylene, either additionally or alternatively.

[0018] In some such examples, the second gas contains acetone, either additionally or as an alternative.

[0019] Another example provides a substrate processing tool. The substrate processing tool includes a processing chamber. The substrate processing tool further includes a conduit for flowing a mixture of a reaction gas and a second gas into the processing chamber. The substrate processing tool further includes a chemical sensor configured to detect the concentration of the second gas in the conduit. The substrate processing tool further includes a mass flow controller located downstream from the chemical sensor along the conduit. The substrate processing tool further includes a system controller configured to receive a signal from the chemical sensor indicating the concentration of the second gas in the conduit. The system controller is further configured to determine the flow offset of the mass flow controller at least based on the signal from the chemical sensor using a lookup table. The system controller is further configured to adjust the mass flow controller based on the determined flow offset.

[0020] In some such examples, the system controller is configured to determine the flow offset of the mass flow controller using a look-up table, further based on the target deposition rate.

[0021] In some such examples, the reaction gas additionally or alternatively comprises acetylene.

[0022] In some such examples, the second gas additionally or alternatively comprises acetone. [Brief Description of the Drawings]

[0023] [Figure 1] A schematic diagram of an exemplary processing tool comprising a chemical sensor and a mass flow controller installed along a conduit leading to a processing chamber.

[0024] [Figure 2] A graph showing exemplary adjustment of the flow offset of a mass flow controller at different acetone concentration levels.

[0025] [Figure 3] A schematic diagram of an exemplary substrate comprising a recessed portion.

[0026] [Figure 4] A flow diagram of an exemplary method for performing flow control correction of a reaction gas based on the detected concentration of a second gas.

[0027] [Figure 5] A schematic block diagram of an exemplary computing system. [Modes for Carrying Out the Invention]

[0028] The term "chemical sensor" generally refers to a device configured to detect the concentration level of one or more process gases. An example of a chemical sensor is an infrared sensor.

[0029] The term "chemical vapor deposition" (CVD) generally refers to a process in which a solid-phase film is formed on a substrate by directing a continuous flow of one or more precursor gases onto the substrate surface under conditions set to cause a chemical conversion of the precursor gases to the film. The term "plasma-enhanced chemical vapor deposition" (PECVD) generally refers to a CVD process in which plasma is used to facilitate the chemical conversion of one or more precursor gases to the solid-phase film on the substrate. Thermal CVD (TCVD) processes use thermal energy to accelerate film formation. The terms "growth," "deposition," and their variations may also be used to mean film formation.

[0030] The term "conduit" generally refers to the flow path through which the process gas flows from the process gas source to the process chamber. The term "downstream" refers to the direction along the flow path toward the process chamber. The term "upstream" refers to the direction along the flow path toward the process gas source.

[0031] The term "CVD tool" generally refers to a machine that includes a processing chamber and other hardware configured to perform CVD processing. The term "PECVD tool" generally refers to a CVD tool configured for PECVD processing.

[0032] The term "mass flow controller" generally refers to a device configured to flow a gas or liquid at a desired flow rate based on a setpoint. The term "setpoint" generally refers to a control input to the mass flow controller related to the desired flow rate. The mass flow controller is configured to regulate the flow rate of the gas or liquid to achieve the setpoint. In some examples, the mass flow controller is calibrated to control a specific type of gas or liquid.

[0033] The term "processing chamber" generally refers to an enclosure in which chemical and / or physical processes are carried out on a substrate. The pressure, temperature, and atmospheric composition within the processing chamber are controllable for carrying out the chemical and / or physical processes.

[0034] The term "processing tool" generally refers to a machine that includes a processing chamber and other hardware configured to enable processing to be performed within the processing chamber.

[0035] The term "reaction gas" generally refers to the process gas involved in the chemical reaction within the processing chamber. Examples of reaction gases include precursor compounds that can be used to deposit films on a substrate. Examples of films include silicon oxide, silicon nitride, and carbon-containing films (e.g., amorphous carbon, silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride). Exemplary carbon-containing reaction gases for depositing carbon-containing films include alkynes (e.g., acetylene (C2H2)). Further examples of carbon-containing reaction gases include alkanes, alkenes (e.g., propylene), cyclic hydrocarbons, aromatics, alkyl halides, alkylamines, and alkyldiamines.

[0036] The term "showerhead" generally refers to a processing gas outlet containing multiple holes distributed throughout a given area.

[0037] The term "stabilizer" generally refers to a compound mixed with a reaction gas to help prevent its degradation before use. An example of a stabilizer is acetone (C3H6O). Acetone can be used to stabilize acetylene. Further examples of stabilizers for acetylene include hydrogen bromide (HBr) and hydrogen iodide (HI). Further examples of stabilizers may include various ketones, ionic liquids, carbenes, silylenes, aldehydes, esters, amides, ethers, amines, and imines.

[0038] As described above, chemical vapor deposition (CVD) deposits films on a substrate using a continuous flow of precursor compounds. Plasma-enhanced CVD (PECVD) uses plasma to accelerate the chemical transformation of precursor compounds and form films on the substrate. For example, carbon-containing films can be deposited using the PECVD process. During PECVD, a carbon-containing reaction gas is introduced into the deposition chamber, a plasma is formed, and a film is formed on the substrate surface by the reactants. Thermal CVD (TCVD) processes use thermal energy to accelerate film formation.

[0039] Some CVD processes use acetylene to deposit carbon-containing films on substrates. Storing and handling acetylene can be difficult. For example, acetylene can react explosively with oxygen. Furthermore, acetylene can decompose explosively without oxygen. In addition, pure acetylene explodes under pressure. Therefore, acetylene may be decomposed with stabilizers for safe storage. Exemplary stabilizers for acetylene include acetone, hydrogen bromide, and hydrogen iodide. The use of stabilizers helps to avoid reactions with oxygen. Decomposing acetylene with stabilizers helps to reduce the pressure in the storage container, which helps to avoid explosive decomposition. Furthermore, stabilizers can help to safely store large quantities of acetylene. Acetone, in particular, has the ability to decompose up to 25 liters of acetylene per liter of acetone.

[0040] However, the ratio of the acetylene flow rate to the total gas flow rate from acetylene mixed with a stabilizer may change with the lifespan of the storage container. Typically, the flow rate of acetylene leaving the storage container decreases over time as a function of the total gas flow rate. This is accompanied by an increase in the flow rate of the stabilizer (e.g., acetylene). For example, acetone gas may account for 0.5% of the total gas flowing out of the storage container in the early stages of its lifespan. In the later stages of the storage container's lifespan, acetone gas can be increased to more than 5% of the flowing gas. As a result, the proportion of acetylene decreases with the lifespan of the storage container.

[0041] Changes in the concentration of the reaction gas can affect the film deposition rate on the substrate. Accordingly, an example of automatic flow correction of the reaction gas is disclosed based on the detected concentration of a second gas (such as a stabilizer gas) flowing with the reaction gas. Briefly, the reaction gas flows from a gas source through a conduit to a processing chamber. A mass flow controller can be used to control the reaction gas flow. The gas source further includes a second gas (such as a stabilizer) that is mixed with the reaction gas. A chemical sensor detects the concentration of the second gas flowing through the conduit. Since the reaction gas is mixed with the second gas in the same storage container, the concentration of the second gas indicates the concentration of the reaction gas. Upon receiving a signal from the chemical sensor, the controller adjusts the mass flow controller to control the flow rate of the reaction gas. In this way, the flow rate of the reaction gas is increased, and changes in the relative concentrations of the second gas and the reaction gas are automatically corrected. This can help avoid processing problems such as a decrease in film growth rate as the reaction gas concentration decreases.

[0042] Measuring the concentration of a second gas can provide a more accurate method of flow control correction than measuring the concentration of the reaction gas. This is because the second gas may contain a relatively lower gas mixture concentration than the reaction gas. For example, as mentioned above, the percentage of acetone flowing out of the storage container can increase from 0.5% to 5% as the storage container lives. Thus, the percentage of acetylene may decrease from 99.5% to 95%. As a result, assuming constant pressure, the acetone concentration may increase by 1000%, while the acetylene concentration may decrease by approximately 5%. Therefore, measuring acetone can provide greater accuracy in determining the gas ratio of the mixture. This helps provide more accurate flow correction adjustment than measuring the acetylene concentration.

[0043] While many examples in this specification describe acetylene gas mixed with acetone gas, the examples disclosed may also apply to other suitable combinations of the reaction gas and the second gas.

[0044] Figure 1 shows an exemplary processing tool 100 that includes sensors to facilitate automatic flow control correction. The processing tool 100 includes a processing chamber 102 and a substrate support 104 within the processing chamber 102. The substrate support 104 is configured to support a substrate 106 placed within the processing chamber 102. The substrate support 104 includes a substrate heater 108. In other examples, the heater may be omitted or located elsewhere within the processing chamber 102.

[0045] The processing tool 100 further includes a shower head 110 positioned within the processing chamber 102. In other examples, the processing tool may include, or in addition to, a nozzle or other device for introducing gas into the processing chamber 102, instead of a shower head. In some examples, the processing tool 100 includes a heater configured to heat the shower head 110.

[0046] The processing tool 100 further includes a reaction gas source 112. The reaction gas source 112 stores a reaction gas 114 and a second gas 116. The reaction gas 114 may contain any suitable compound that can be used to process the substrate in the processing chamber 102. In some examples, the reaction gas contains acetylene (C2H2). The second gas 116 may contain any suitable gas that can be mixed with the reaction gas 114. In some examples, the second gas 116 contains a stabilizer that helps to stabilize the reaction gas 114. For example, in an example where the reaction gas 114 contains acetylene, the second gas 116 may contain acetone. As mentioned above, acetone helps to stabilize acetylene. In some examples, acetone can decompose acetylene by more than 25 times by volume. In other examples, hydrogen halides (HBr, HI, etc.) may be used to stabilize the acetylene. Further examples of stabilizers may include various ketones, ionic liquids, carbenes, silylenes, aldehydes, esters, amides, ethers, amines, and imines.

[0047] The processing tool 100 may optionally include a storage container sensor 118. Any storage container sensor 118 may be configured to detect pressure within the reaction gas source 112 or to detect the weight of the reaction gas source 112. For example, the detected weight of the reaction gas source 112 can help estimate the amount of gas remaining in the reaction gas source 112. Furthermore, the detected pressure within the reaction gas source 112 can help indicate the relative ratio of reaction gas 114 to second gas 116. Therefore, the detected weight and / or detected pressure may be used to estimate the amount of reaction gas 114 and second gas 116 remaining in the reaction gas source 112. In some examples, the processing tool 100 may include both a pressure sensor and a weight sensor for the reaction gas source. In other examples, such sensors may be omitted.

[0048] The processing tool 100 further comprises a conduit 120 connecting a reaction gas source 112 to a processing chamber 102. In some examples, the reaction gas source 112 includes a regulator to help control the gas flow to the conduit 120. For example, the regulator can be used to cause reaction gas 114 and a second gas 116 to flow out of the reaction gas source 112 at a selected flow rate and / or to achieve a selected pressure within the conduit 120. In some examples, the processing tool 100 may include one or more additional conduits for connecting additional processing gas sources to the processing chamber 102. Further examples of processing gases include silicon-containing precursors (e.g., silane), inert gases (e.g., argon), oxygen gas, and hydrogen gas. In such examples, the processing tool 100 may include one or more valves and an additional mass flow controller for controlling the flow rates of other processing gases.

[0049] The processing tool 100 further includes an exhaust system 132. The exhaust system 132 is configured to discharge gas from the processing chamber 102. The exhaust system 132 may include any suitable hardware, including one or more low vacuum pumps, one or more high vacuum pumps, and one or more valves for controlling the exhaust flow. In some examples, the exhaust system 132 can operate to achieve a selected pressure in the processing chamber 102 during substrate processing. Furthermore, the exhaust system 132 can operate to purge the processing chamber 102.

[0050] The processing tool 100 further includes a high-frequency power supply 134 electrically connected to the showerhead 110. The high-frequency power supply 134 is configured to form a plasma in the processing chamber 102 by supplying high-frequency power to the showerhead 110. For example, during PECVD, the high-frequency power supply 134 can operate to form a plasma using a reaction gas 114 to deposit a film (e.g., a carbon-containing film). In the example shown in the figure, a capacitively coupled plasma may be formed between the showerhead 110 and the substrate support 104 in the processing chamber 102. In various examples, the high-frequency power may be supplied to the showerhead electrode or the substrate holder electrode. As shown in Figure 1, the high-frequency energy is supplied to the showerhead 110 and the substrate support 104 is configured as a grounded counter electrode. In other examples, the high-frequency power supply 134 can supply high-frequency power to the substrate support 104 and the showerhead 110 may be grounded.

[0051] The processing tool 100 further includes a matching network 136 for impedance matching of the high-frequency power supply 134. The high-frequency power supply 134 may be configured to provide high-frequency energy of any suitable frequency and power. Exemplary frequencies include 400 kHz, 13.56 MHz, 27 MHz, 60 MHz, and 90 MHz. Examples of high-frequency power include power from 100 W to 6500 W. In other examples, high-frequency power outside this range may be used. In some examples, the high-frequency power supply 134 is configured to operate at multiple different frequencies and / or powers.

[0052] The processing tool 100 further includes a mass flow controller 140 located along the conduit 120. The mass flow controller 140 is configured to control the flow rate of the reaction gas 114 flowing into the processing chamber 102. The mass flow controller 140 can control the flow rate of the reaction gas 114 based on a setpoint, that is, to achieve a selected flow rate indicated by the setpoint. In some examples, the setpoint is within the range of 10% to 90% of the flow capacity of the mass flow controller. In other examples, a setpoint outside this range may be used. In some examples, the mass flow controller 140 may further control the flow rate of the reaction gas 114 based on a flow offset relative to the setpoint. In some examples, the mass flow controller 140 may include a thermal mass flow controller. In other examples, any other suitable flow controller may be used.

[0053] The processing tool 100 further includes a chemical sensor 142 located along the conduit 120. The chemical sensor 142 is positioned upstream of the mass flow controller. Upstream means in the opposite direction to the gas flow through the conduit 120 from the reaction gas source 112 to the processing chamber 102. Downstream means in the direction toward the processing chamber 102 along the conduit. As shown in Figure 2, the mass flow controller 140 is positioned along the conduit between the chemical sensor 142 and the processing chamber 102. The chemical sensor 142 is configured to detect the concentration of the second gas 116 in the conduit 120. The chemical sensor 142 may include any suitable sensor. Examples include a spectroscopic sensor (e.g., an infrared (IR) sensor). For example, an infrared sensor may be configured to detect infrared absorption corresponding to the second gas 116. Since the absorption increases with increasing concentration of the second gas 116, the output signal of the infrared sensor indicates the increasing concentration of the second gas 116 flowing through the conduit 120. In some examples, different types of spectroscopic sensors (e.g., visible light sensors) may be used.

[0054] The processing tool 100 further includes a system controller 150 configured to control the operation of the processing tool. The system controller 150 is operably connected to a substrate heater 108, an exhaust system 132, a high-frequency power supply 134, a mass flow controller 140, a chemical sensor 142, and, if necessary, a storage container sensor 118. The system controller 150 is configured to control various functions of the processing tool 100 to carry out chemical deposition. For example, the system controller 150 is configured to control the mass flow controller 140 to flow the reaction gas 114 into the processing chamber 102 at a selected rate. The system controller 150 is also configured to control the processing tool 100 to operate the substrate heater 108 to heat the substrate to a desired temperature. The system controller 150 is also configured to operate the exhaust system 132 to remove gas from the processing chamber 102. The system controller 150 is also configured to operate the high-frequency power supply 134 to form a plasma, as well as to control any other suitable functions of the processing tool 100.

[0055] Furthermore, the system controller 150 is also configured to receive signals from the chemical sensor 142 and adjust the mass flow controller 140 based on the signals received from the chemical sensor 142. For example, the system controller 150 can determine the offset of the mass flow controller 140 and adjust the setpoint of the mass flow controller 140. As described above, the amount of reaction gas 114 flowing out from the reaction gas source 112 may change in proportion to the second gas 116 as the storage container reaches the end of its life. For example, the acetylene concentration tends to decrease towards the end of the storage container's life, while the acetone concentration tends to increase. A low acetylene concentration in the reaction gas flowing through the conduit 120 may cause a decrease in the deposition rate of the film deposited on the substrate 106. Therefore, in response to the signal from the chemical sensor 142, the system controller 150 may adjust the flow offset to the setpoint of the mass flow controller 140 to maintain the target deposition rate.

[0056] The effect of flow offset on deposition rate is schematically shown in Figure 2. Figure 2 shows graph 200 of exemplary deposition rates for PECVD of carbon-containing films using acetylene gas. Line 202 shows deposition rate versus acetylene flow offset for gas mixtures with "low acetone concentration". For example, acetylene dissolved in acetone can release a gas mixture containing approximately 99.5% acetylene and 0.5% acetone in the early stages of the storage container's life. This gas mixture represents a relatively low concentration of acetone. In such an example, later in the life of the storage container, this ratio may change to 95% acetylene and 5% acetone. This represents a relatively high concentration of acetone. Line 204 shows deposition rate versus acetylene flow offset for such gas mixtures with "high acetone concentration".

[0057] The deposition rate can be adjusted by changing the flow offset of the acetylene gas. As shown in Graph 200, both lines 202 and 204 have a positive slope. This is because the deposition rate increases with increasing acetylene gas flow. Furthermore, line 204 shows a lower deposition rate than line 202. This is because line 204 corresponds to a relatively smaller percentage of acetylene (95% acetylene) than line 202 (99.5% acetylene). Therefore, the deposition rate of line 204 is lower than the deposition rate of line 202 for the selected flow offset.

[0058] Therefore, the mass flow controller may be adjusted to help achieve the target deposition rate 206. As shown in graph 200, line 202 intersects the target deposition rate 206 at flow offset 208. Therefore, when the acetylene gas contains a low acetone concentration (line 202), the acetylene flow offset may be adjusted to flow offset 208. Furthermore, when the acetylene gas contains a high acetone concentration (line 204), the acetylene flow offset may be adjusted to flow offset 210.

[0059] Referring again to Figure 1, the system controller 150 can adjust the mass flow controller 140 (for example, adjust the offset) based on the concentration of the second gas detected by the chemical sensor 142. For example, when the system controller 150 detects a low acetone concentration represented by line 202, it may adjust the mass flow controller 140 to a flow offset 208. This can help achieve the target deposition rate 206. When the reaction gas source 112 is empty, the acetone concentration in the gas mixture flowing through the conduit 120 tends to increase. This is accompanied by a decrease in the acetylene concentration. When the chemical sensor 142 detects a high acetone concentration represented by line 204, the system controller 150 may adjust the mass flow controller 140 to a flow offset 210. This can help maintain the deposition rate at the target deposition rate 206. In this way, the system controller 150 can automatically maintain the deposition rate of the film deposited on the substrate 106 according to the concentration of the second gas 116 detected by the chemical sensor 142.

[0060] In some examples, the adjustment of the mass flow controller 140 may be performed using a lookup table. The lookup table may include reaction gas flow offset values ​​for each of several values ​​for the concentration of the second gas 116. In such examples, the system controller 150 can refer to the lookup table to determine the reaction gas flow offset based at least on the concentration of the second gas detected by the chemical sensor 142. In some examples, the reaction gas flow offset value in the lookup table is further based on the setpoint of the reaction gas flow. In some examples, the reaction gas flow offset value in the lookup table is further based on the target deposition rate (e.g., target deposition rate 206). In further examples, the reaction gas flow offset value in the lookup table is further based on the pressure and / or weight detected by the storage container sensor 118. The lookup table may be process-dependent. Specifically, different lookup tables may be constructed for different processes. The predetermined lookup tables may be stored in memory (e.g., a storage subsystem) accessible by the system controller 150. Examples of computing systems and storage subsystems are described in more detail below in relation to Figure 5.

[0061] In some examples, the signal from the storage container sensor 118 may be used alternatively or additionally to adjust the mass flow controller 140. For example, the storage container sensor 118 may include a weight sensor. When the reaction gas source 112 is empty, the storage container sensor 118 may detect a decrease in the weight of the reaction gas source 112. Since the weight corresponds to the amount of chemical remaining in the storage container, it can be used to estimate the ratio of the amount of reaction gas to the second gas that has flowed out of the reaction gas source 112. For example, the value of the reaction gas flow offset in the lookup table (or other adjustments to the mass flow controller) may be based further on the pressure in the conduit 120. Similarly, the detected pressure may be used to estimate the ratio of the amount of reaction gas to the second gas that has flowed out of the reaction gas source 112. Thus, the signal from the storage container sensor 118 may be used to estimate the concentration of the reaction gas 114 flowing through the conduit 120. Therefore, in some examples, the system controller 150 is configured to adjust the mass flow controller 140 based at least on the signal detected by the storage container sensor 118. In some examples, signals from both the chemical sensor 142 and the storage container sensor 118 may be used to adjust the mass flow controller 140. However, due to variations in the supply of the reaction gas source, the chemical sensor 142 can provide a more accurate determination of the second gas concentration than the storage container sensor 118.

[0062] In some examples, relatively slow film growth can be at least partially compensated by control adjustments other than the reaction gas flow rate. Examples include increasing the temperature or increasing the high-frequency power supplied to the plasma. For example, the system controller 150 may operate the substrate heater 108 to heat the substrate 106 to different temperatures in response to a signal from the chemical sensor 142. Another example is that the system controller 150 may operate the high-frequency power supply 134 to supply different high-frequency power in response to a signal from the chemical sensor 142. However, in some examples, these control adjustments may result in different film growth rates at different locations on the features on the substrate. This issue is illustrated in Figure 3, which shows an exemplary substrate 300 containing a feature 302. The substrate 300 includes a film 303 deposited on the substrate and the surface of the feature 302. The film 303 is schematically shown with an inward-facing shape. In various exemplary CVD processes, techniques such as etching or suppression may be used to deposit films that are more conformal or non-conformal than film 303. In some cases, increasing the high-frequency power can help increase the film growth rate on surface 304 near the opening of feature 302. However, even with the increased high-frequency power, the film growth rate on the upper wall surface 306 may be relatively slower than that on surface 304. Furthermore, the film growth rate on the lower wall surface 308 near the bottom of feature 302 may be even slower. Non-uniform growth rates can result in films with different film thicknesses and / or conformation outside the tolerance range of the selected process. This can affect device performance. Additionally, in some cases, adjustments to temperature, pressure, and / or high-frequency power can affect film quality.

[0063] Therefore, examples of disclosures for implementing automatic flow correction of the reaction gas can help maintain the film growth rate without uneven deposition caused by different proportions of the reaction gas and a second gas (e.g., stabilizer). For example, by adjusting the mass flow controller 140 to increase the flow rate of the reaction gas 114, the film growth rates on the surface 304, the upper wall 306, and the lower wall 308 can all be controlled according to the desired process. This helps avoid film growth outside the acceptable range of the selected process. Furthermore, by compensating for the reduced reaction gas concentration with an increase in flow rate, the desired film growth can be maintained without affecting film quality.

[0064] Figure 4 shows a flow diagram of an exemplary method 400 for adjusting the flow rate of the reaction gas based on the detected concentration of the second gas. Method 400 may be used to control a processing tool (e.g., processing tool 100). Method 400 may be implemented by, for example, a system controller 150.

[0065] Method 400 includes, in 402, a step of controlling the flow of reaction gas and a second gas through the conduit to the processing chamber using a mass flow controller. In 404, Method 400 further includes a step of detecting the concentration of the second gas flowing through the conduit using a chemical sensor located along the conduit. The chemical sensor is located upstream of the mass flow controller. Therefore, the mass flow controller is located along the conduit between the chemical sensor and the processing chamber. For example, chemical sensor 142 is located along conduit 120 and is located upstream of mass flow controller 140. In some examples, Method 406 includes a step of detecting the concentration of the second gas using an infrared sensor. In other examples, any other suitable chemical sensor may be used.

[0066] Method 400 further includes, in 408, the step of adjusting the mass flow controller based at least on the concentration of the detected second gas. In some examples, the method includes, in 410, the step of adjusting the flow offset of the mass flow controller. In some examples, the method includes, in 412, the step of adjusting the mass flow controller based further on the target deposition rate. In some examples, in 414, the step of adjusting the mass flow controller includes using a lookup table. For example, the lookup table may be used to determine the flow offset based on the concentration of the detected second gas. In some such examples, the flow offset is further based on the target deposition rate. For example, as described above with respect to Figure 2, the deposition rate of the carbon-containing film may be relatively lower for a mixture of acetone gas and acetylene gas with a relatively high acetone concentration (line 204) than for a mixture with a relatively low acetone concentration (line 202). Thus, the flow offset of the mass flow controller can be adjusted to a flow offset 210 based on the target deposition rate 206.

[0067] In some examples, in 416 the reaction gas includes a carbon-containing gas, and method 400 further includes the step of depositing a carbon-containing film on a substrate. Examples of carbon-containing films include silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon oxycarbonitride. Examples of carbon-containing gases for forming such films include alkanes, alkenes (e.g., propylene), alkynes (e.g., acetylene), cyclic hydrocarbons, aromatics, alkyl halides, alkylamines, and alkyldiamines. In some examples, in 418 the carbon-containing gas includes acetylene. In other examples, any other suitable reaction gas may be used to deposit the carbon-containing film. In some such examples, in 420 the second gas includes acetone. As mentioned above, acetone may be used as a stabilizer to stabilize the acetylene. In other examples, any other suitable reaction gas may be used for film formation.

[0068] Therefore, examples of disclosure may be provided for automatically correcting the reaction gas flow rate based on the detected concentration of a second gas. Adjusting the reaction gas flow rate can help maintain the deposition rate at a target deposition rate. This can help avoid processing problems such as slow film growth. These examples avoid adjustments to temperature, pressure, high-frequency power, or other processing conditions by adjusting the flow rate in a mass flow controller. This can help maintain the deposition rate while avoiding non-uniform film growth in some examples. This can also help protect film quality.

[0069] Figure 5 schematically shows an example of a computing system 500 capable of performing one or more of the methods and processes described above. The computing system 500 is shown in a simplified form. The computing system 500 may take the form of one or more personal computers, workstations, computers integrated with board processing tools, and / or network-accessible server computers.

[0070] The computing system 500 includes a logical subsystem 502 and a storage subsystem 504. The computing system 500 may optionally include a display subsystem 506, an input subsystem 508, a communication subsystem 510, and / or other components not shown in Figure 5. The system controller 150 is an example of the computing system 500.

[0071] The logical subsystem 502 includes one or more physical devices configured to execute instructions. For example, the logical subsystem may be configured to execute instructions that are part of one or more applications, services, programs, routines, libraries, objects, components, data structures, or other logical configurations. Such instructions can be executed to perform a task, implement a data type, change the state of one or more components, achieve a technical effect, or reach a desired result.

[0072] A logical subsystem may include one or more processors configured to execute software instructions. Additionally or alternatively, a logical subsystem may include one or more hardware logical subsystems or firmware logical subsystems configured to execute hardware instructions or firmware instructions. The processors of a logical subsystem may be single-core or multi-core, and the instructions executed thereon may be configured for sequential, parallel, and / or distributed processing. Individual components of a logical subsystem may be distributed, as necessary, between two or more separate devices located remotely and / or configured for collaborative processing. Embodiments of a logical subsystem may be virtualized and executed by remotely accessible network computing devices configured in a cloud computing configuration.

[0073] The storage subsystem 504 includes one or more physical devices configured to hold instructions 512 executable by the logical subsystem and to carry out the methods and processes described herein. When such methods and processes are carried out, the state of the storage subsystem 504 may be transformed, for example, to hold different data.

[0074] The storage subsystem 504 may include removable devices and / or internal devices. The storage subsystem 504 may include, among other things, optical memory (e.g., CD, DVD, HD-DVD, Blu-ray disc, etc.), semiconductor memory (e.g., RAM, EPROM, EEPROM, etc.), and / or magnetic memory (e.g., hard disk drives, floppy disk drives, tape drives, MRAM, etc.). The storage subsystem 504 may include volatile devices, non-volatile devices, dynamic devices, static devices, read-write devices, read-only devices, random access devices, sequential access devices, location reference devices, file reference devices, and / or associative devices.

[0075] It will be recognized that the storage subsystem 504 includes one or more physical devices. However, instructions in the embodiments described herein may alternatively be transmitted by a communication medium (e.g., electromagnetic signals, optical signals, etc.) that is not held by a physical device for a finite duration.

[0076] Embodiments of the logic subsystem 502 and the storage subsystem 504 can be integrated into one or more hardware logic components. Such hardware logic components may include, for example, field-programmable gate arrays (FPGAs), programmatic and application-specific integrated circuits (PASICs / ASICs), programmatic and application-specific standard products (PSSPs / ASSPs), systems-on-a-chip (SOCs), and composite programmable logic devices (CPLDs).

[0077] When a display subsystem 506 is included, it may be used to present a visual representation of the data held by the storage subsystem 504. This visual representation may take the form of a graphical user interface (GUI). Since the methods and processes described herein modify the data held by the storage subsystem and thereby transform the state of the storage subsystem, the state of the display subsystem 506 may also be transformed to visually represent the changes in the underlying data. The display subsystem 506 may include one or more display devices using virtually any kind of technology. Such display devices may be combined with the logical subsystem 502 and / or the storage subsystem 504 in a shared enclosure, or they may be peripheral display devices.

[0078] When an input subsystem 508 is included, it may have or be connected to one or more user input devices (such as a keyboard, mouse, or touchscreen). In some examples, the input subsystem may have or be connected to selected natural user input (NUI) components. Such components may be integrated or peripheral devices, and the transmission and / or processing of input actions may be operated onboard or offboard. Exemplary NUI components may include a microphone for speech recognition and / or voice recognition, an infrared color stereoscope, and / or a depth camera for machine vision and / or gesture recognition.

[0079] When a communication subsystem 510 is included, the computing system 500 can be configured to communicate with one or more other computing devices. The communication subsystem 510 may include wired and / or wireless communication devices compatible with one or more different communication protocols. In a non-limiting example, the communication subsystem may be configured for communication over a wireless telephone network, or over a wireless or wired local or wide-area network. In some examples, the communication subsystem may enable the computing system 500 to send and receive messages with other devices over a network such as the Internet.

[0080] The configurations and / or methods described herein are essentially examples, and many modifications are possible; therefore, it will be understood that these particular examples should not be taken as limiting. The specific routines or methods described herein may represent one or more of any number of processing strategies. Thus, the various actions described herein may be performed in parallel, in any other order, or omitted, in the order described herein or elsewhere. Similarly, the order of the processes described above may be changed.

[0081] The subject matter of this disclosure includes all novel and non-trivial combinations and subcombinations of the various processes, systems, and configurations disclosed herein, as well as other features, functions, actions, and / or characteristics, and all their equivalents.

Claims

1. A circuit board processing tool, Processing chamber and A conduit for flowing a mixture of the reaction gas and the second gas into the processing chamber, A chemical sensor configured to detect the concentration of the second gas in the conduit, A mass flow controller installed downstream from the chemical sensor along the aforementioned conduit, System controller, A signal indicating the concentration of the second gas in the conduit is received from the chemical sensor. The mass flow controller is adjusted based on the aforementioned signal and the set point of the reaction gas. A system controller configured as follows, A substrate processing tool equipped with the following features.

2. A substrate processing tool according to claim 1, The aforementioned reaction gas is a substrate processing tool containing acetylene.

3. A substrate processing tool according to claim 2, The second gas is a substrate processing tool containing a stabilizer.

4. A substrate processing tool according to claim 3, The aforementioned stabilizer is a substrate processing tool containing acetone.

5. A substrate processing tool according to claim 1, The chemical sensor is a substrate processing tool that includes an infrared sensor.

6. A substrate processing tool according to claim 1, The aforementioned chemical sensor is a substrate processing tool that includes a visible light sensor.

7. A substrate processing tool according to claim 1, The system controller is configured to adjust the flow offset of the mass flow controller using a lookup table, and is a substrate processing tool.

8. A substrate processing tool according to claim 1, The processing tool is a substrate processing tool configured to form a film by creating a plasma using the reaction gas.

9. A method for controlling a circuit board processing tool, A process of controlling the flow of reaction gas and a second gas through a conduit towards the processing chamber of the substrate processing tool using a mass flow controller, A step of detecting the concentration of the second gas flowing through the conduit using a chemical sensor located along the conduit, wherein the chemical sensor is installed upstream of the mass flow controller, A step of adjusting the mass flow controller based at least on the concentration of the detected second gas, Methods that include...

10. The method according to claim 9, A method comprising the step of detecting the concentration of the second gas, wherein the step of using an infrared sensor is included.

11. The method according to claim 9, A method for adjusting the mass flow controller, comprising adjusting the flow offset of the mass flow controller.

12. The method according to claim 9, The method for adjusting the mass flow controller includes using a lookup table.

13. The method according to claim 12, The step of adjusting the flow rate of the gas mixture is a method further based on the target deposition rate.

14. The method according to claim 9, The method further comprises the step of depositing a carbon-based film on a substrate placed in the processing chamber, wherein the reaction gas contains a carbon-containing gas.

15. The method according to claim 14, The method wherein the carbon-containing gas includes acetylene.

16. The method according to claim 15, The method wherein the second gas comprises acetone.

17. A circuit board processing tool, Processing chamber and A conduit for flowing a mixture of the reaction gas and the second gas into the processing chamber, A chemical sensor configured to detect the concentration of the second gas in the conduit, A mass flow controller installed downstream from the chemical sensor along the aforementioned conduit, System controller, A signal indicating the concentration of the second gas in the conduit is received from the chemical sensor. Using a lookup table, the flow offset of the mass flow controller is determined at least based on the signal from the chemical sensor. The mass flow controller is adjusted based on the flow offset determined above. A system controller configured as follows, A substrate processing tool equipped with the following features.

18. A substrate processing tool according to claim 17, A substrate processing tool, wherein the system controller is configured to determine the flow offset of the mass flow controller based on the target deposition rate using the lookup table.

19. A substrate processing tool according to claim 17, The aforementioned reaction gas is a substrate processing tool containing acetylene.

20. A substrate processing tool according to claim 19, The second gas is a substrate processing tool containing acetone.

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