In-situ epitaxial growth rate control of crystal thickness using parametric resonance sensing

Abstract

A method and apparatus for processing a semiconductor substrate are described herein. The apparatus includes one or more growth monitors disposed within an exhaust system of a deposition chamber. The growth monitor is a parametric resonance monitor configured to measure a film thickness grown on the growth monitor while a substrate is being processed within the deposition chamber. The growth monitor is connected to a controller that adjusts settings of a heating device and a gas flow device during a processing step. Using measurements from the growth monitor as well as other sensors within the deposition chamber, a process chamber model of the deposition chamber is adjusted when a substrate is being processed therein.

Description

Technical Field

[0001]

[0001] Embodiments of the present disclosure generally relate to apparatuses and methods for manufacturing semiconductor devices. More specifically, the apparatuses disclosed herein relate to an exhaust assembly and a growth rate sensor within a semiconductor process chamber. Methods using the same are also disclosed.

Background Art

[0002]

[0002] Semiconductor substrates are processed for various applications including the manufacture of integrated devices and microdevices. During processing, the substrate is positioned on a susceptor within a process chamber. The susceptor is supported by a support shaft that is rotatable about a central axis. Through precise control of the heating source, the substrate is uniformly heated within tight tolerances. The temperature of the substrate can affect the uniformity of the material deposited on the substrate.

[0003]

[0003] The ability to monitor the growth / deposition thickness within a process chamber has a significant impact on throughput and production yield. Currently, in epitaxial reactors, in situ monitoring of growth / deposition thickness is not generally performed. Currently, the process is time adjusted to achieve the desired thickness, and then the thickness is measured ex situ outside the process chamber. In conventional attempts to incorporate sensors within the process chamber, there are limitations in resolution, and adding sensors increases the downtime and ownership cost of the process chamber. Even attempts to offset these costs still do not result in a direct measurement of mass. Also, the substrate processed between the calibration and measurement steps has a reduced deposition rate accuracy due to changes in chamber conditions. Current sensors within the process chamber include pyrometers and pressure sensors, but these do not provide the determination accuracy of the desired film growth.

[0004]

[0004] Therefore, there is a need to improve the monitoring of growth rate.

Summary of the Invention

[0005]

[0005] This disclosure generally relates to apparatuses and methods for manufacturing semiconductor devices. More specifically, the apparatuses disclosed herein relate to an exhaust assembly and a growth rate sensor within a semiconductor process chamber. Methods of using them are also disclosed.

[0006]

[0006] In another embodiment, an exhaust system for substrate processing is disclosed. The exhaust system includes a first exhaust plenum, a first exhaust inlet opening fluidly connected to the first exhaust plenum, a first plurality of fins disposed within the first exhaust plenum adjacent to the first exhaust inlet opening, a first exhaust outlet opening fluidly connected to the first exhaust plenum, a first baffle plate disposed adjacent to the first exhaust outlet opening and configured to narrow the width of the first exhaust plenum, and at least one growth monitor disposed downstream of the first baffle plate. The growth monitor is configured to measure the thickness of the material deposited on the growth monitor. The at least one growth monitor is a parametric resonance sensor.

[0007]

[0007] Another embodiment is a processing system suitable for semiconductor substrate processing. The processing system includes a chamber body forming a process region, a substrate support, an upper window, a lower window, an injector, and an exhaust system. The substrate support is disposed within the process region of the chamber body. The upper window is disposed above the substrate support, and the lower window is disposed below the substrate support. The upper window and the lower window define the process region. The injector is disposed through one side of the chamber body and configured to introduce a process gas into the process region. The exhaust system is disposed through a second side of the chamber body opposite the injector. The exhaust system includes at least one growth monitor configured to measure the thickness of the material deposited on the growth monitor. The growth monitor is a parametric resonance sensor.

[0008]

[0008] In another embodiment, a controller of a process system storing instructions is disclosed. When executed by a processor, the controller causes the system to process a substrate in a processing chamber by flowing a process gas from a process gas inlet into a process region, depositing the gas onto a substrate, and exhausting the process gas through an exhaust system. The exhaust system further includes a growth monitor. The growth monitor includes a parametric resonance sensor. The controller further causes the system to deposit a process gas on the growth monitor, measure film growth on the growth monitor, calculate a film growth rate on the substrate, and adjust processing chamber parameters.

[0009]

[0009] To enable a more detailed understanding of the features of the present disclosure described above, the present disclosure summarized above will be described more specifically with reference to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings show only exemplary embodiments and should not be regarded as limiting the scope, and the present disclosure may admit other equally effective embodiments.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0018] For ease of understanding, the same reference numbers are used as much as possible to indicate the same elements common to the drawings. It is assumed that the elements and features of one embodiment can be beneficially incorporated into other embodiments without further detailed description.

[0012]

[0019] The present disclosure relates to an exhaust assembly and a growth rate sensor in a semiconductor process chamber. The growth rate sensor is a parametric resonance film thickness monitor, which enables measurement of the film thickness on the growth rate sensor. The film thickness on the growth rate sensor is equivalent to the growth rate on the substrate in the process chamber. Using this thickness measurement value, one or more process controls in the process area of the process chamber can be adjusted to improve film growth across the substrate.

[0013]

[0020] The sensitivity and the sensor life cycle are improved by the position and number of the parametric resonance monitors. The configuration of the exhaust system around the parametric resonance monitor further increases the process gas flow across the parametric resonance monitor to improve the growth rate on the parametric resonance monitor while maintaining the gas flow in the process area in the same way or minimizing the influence of the flow. Therefore, the exhaust system may include a configuration of fins and baffles for controlling the gas flow rate. The fins, baffles, and other components of the exhaust system may further be formed of, or coated with, a material that enhances the heat retention of the process gas when the process gas flows through the exhaust system. This makes the film growth on the parametric resonance monitor more predictable.

[0014]

[0021] The software algorithm within the process chamber controller captures the growth rate measurements from the parametric resonance monitor and enables calibration with other sensors within the process chamber and the process conditions within the process chamber to improve the film thickness growth rate.

[0015]

[0022] FIG. 1 is a schematic diagram of a deposition chamber 100 according to an embodiment of the present disclosure. The deposition chamber 100 is an epitaxial deposition chamber. The deposition chamber 100 is used to grow an epitaxial film on a substrate such as the substrate 102. The deposition chamber 100 forms a cross-flow of precursors across the upper surface 150 of the substrate 102.

[0016]

[0023] The deposition chamber 100 includes an upper body 156, a lower body 148 disposed below the upper body 156, and a flow module 112 disposed between the upper body 156 and the lower body 148. The upper body 156, the flow module 112, and the lower body 148 form a chamber body. Disposed within the chamber body are a substrate support 106, an upper window 108, a lower window 110, a plurality of upper lamps 141, and a plurality of lower lamps 143. As shown, the controller 120 communicates with the deposition chamber 100 and is used to control the processes as described herein. The substrate support 106 is disposed between the upper window 108 and the lower window 110. The plurality of upper lamps 141 are disposed between the upper window 108 and the lid 154. The plurality of upper lamps 141 form part of an upper lamp module 155. The lid 154 may include a plurality of sensors (not shown) disposed therein for measuring the temperature within the deposition chamber 100. The plurality of lower lamps 143 are disposed between the lower window 110 and the floor 152. The plurality of lower lamps 143 form part of a lower lamp module 145. The upper window 108 is an upper dome and is formed of an energy transmissive material such as quartz. The lower window 110 is a lower dome and is formed of an energy transmissive material such as quartz.

[0017]

[0024] The process region 136 is formed between the upper window 108 and the lower window 110. The process region 136 has a substrate support 106 disposed therein. The substrate support 106 includes an upper surface on which the substrate 102 is disposed. The substrate support 106 is attached to a shaft 118. The shaft is connected to an operation assembly 121. The operation assembly 121 includes one or more actuators and / or adjustment devices that provide movement and / or adjustment of the shaft 118 and / or the substrate support 106 within the process region 136.

[0018]

[0025] The substrate support 106 may include lift pin holes 107 disposed therein. The lift pin holes 107 are sized to accommodate lift pins 132 for lifting the substrate 102 from the substrate support 106 either before or after the deposition process is performed. The lift pins 132 may rest on the lift pin stops 134 when the substrate support 106 is lowered from the process position to the transfer position.

[0019]

[0026] The flow module 112 includes a plurality of process gas inlets 114, a plurality of purge gas inlets 164, and one or more exhaust gas outlets 116. The plurality of process gas inlets 114 and the plurality of purge gas inlets 164 are disposed on the side opposite to one or more exhaust gas outlets 116 of the flow module 112. One or more flow guides are disposed below the plurality of process gas inlets 114 and one or more exhaust gas outlets 116. The flow guide is disposed above the purge gas inlet 164. A liner 163 is disposed on the inner surface of the flow module 112 to protect the flow module 112 from the reactive gases used during the deposition process. The process gas inlets 114 and the purge gas inlets 164 are positioned to flow gas parallel to the upper surface 150 of the substrate 102 disposed in the process region 136. The process gas inlets 114 are fluidly connected to a process gas source 151. The purge gas inlets 164 are fluidly connected to a purge gas source 162. One or more exhaust gas outlets 116 are fluidly connected to an exhaust pump 157.

[0020]

[0027] One or more exhaust gas outlets 116 are further connected to, or include, an exhaust system. The exhaust system fluidly connects one or more exhaust gas outlets 116 and the exhaust pump 157. The exhaust system described herein includes one or more growth monitors 310 (FIG. 3A) and is configured to assist in the controlled deposition of layers on the substrate 102.

[0021]

[0028] FIG. 2 is a cross-sectional plan view showing the deposition chamber 100 of FIG. 1 according to an embodiment of the present disclosure. The deposition chamber 100 includes an injector 202 disposed on the opposite side of the exhaust system 178. The injector 202 includes a process gas inlet 114 and is fluidly coupled to a process gas source 151. The injector 202 may be disposed to penetrate at least a part of the flow module 112 or may be a part of the flow module 112. The exhaust system 178 is disposed on the side opposite to the injector 202 in the process region 136. The exhaust system 178 is formed to penetrate the flow module, or is attached to the flow module, or is a part of the flow module.

[0022]

[0029] The exhaust system 178 further includes at least one exhaust passage body 204a, 204b. The exhaust passage bodies 204a, 204b form an exhaust path for the gas exiting the process region 126 before entering the exhaust collector 206. As shown in FIG. 2, there are a first exhaust passage body 204a and a second exhaust passage body 204b. The first exhaust passage body 204a and the second exhaust passage body 204b are mirror images and may be similar in size and configuration. In other embodiments, there may be more or fewer exhaust passage bodies 204a, 204b. In some embodiments, there is only one exhaust passage body, and the two exhaust passage bodies 204a, 204b are integrated into a single body. In still other embodiments, there may be three or more exhaust passage bodies, such as three exhaust passage bodies 204a, 204b. The size and configuration of the exhaust passage bodies 204a, 204b can be changed according to the size and process of the deposition chamber 100.

[0023]

[0030] Both the first exhaust passage body 204a and the second exhaust passage body 204b are coupled to the exhaust collector 206 at the end of the exhaust passage bodies 204a, 204b opposite to the process region 136. The exhaust collector 206 is configured to collect the exhaust from the first exhaust passage body 204a and the second exhaust passage body 204b. The exhaust collector 206 narrows as it moves away from the exhaust passage bodies 204a, 204b.

[0024]

[0031] FIG. 3A is a cross-sectional plan view showing an exhaust system 178 of the deposition chamber 100 of FIG. 1 according to an embodiment of the present disclosure. The exhaust system 178 is configured to control an exhaust gas flow exiting the process region 126 before flowing over one or more growth monitors 310. When the flow rate on the growth monitor 310 increases relative to the flow rate at the inlets of the exhaust passage bodies 204a, 204b, the film growth on the growth monitor 310 is promoted. Accordingly, the width of each of the exhaust passage bodies 204a, 204b is narrowed from the inlet width W1 to the outlet width W2, increasing the flow rate. The fin array 314 and one or more baffles 304 are positioned within each of the exhaust passage bodies 204a, 204b, reducing the impact of the narrowing on the flow path of the process gas through the process region 136 while allowing the exhaust passage bodies 204a, 204b to be narrowed.

[0025]

[0032] When the process gas flows out of the process region 136 into the exhaust system 178, the process gas flows through a first flow path 318. The first flow path 318 is mainly parallel to the surface of the substrate 136, and gas flows out from the injector 202. The process gas flows into the exhaust system 178 through exhaust inlet openings 305a, 305b disposed through each of the exhaust passage bodies 204a, 204b. Accordingly, the first exhaust inlet opening 305a is disposed through the first end of the first exhaust passage body 204a, and the second exhaust inlet opening 305b is disposed through the first end of the second exhaust passage body 204b. The exhaust inlet openings 305a, 305b are in fluid communication with exhaust plenums 312a, 312b. The exhaust plenums 312a, 312b are disposed within each of the exhaust passage bodies 204a, 204b. Accordingly, the first exhaust plenum 312a is disposed within the first exhaust passage body 204a, and the second exhaust plenum 312b is disposed within the second exhaust passage body 204b. The first exhaust inlet opening 305a is in fluid communication with the first exhaust plenum 312a, and the second exhaust inlet opening 305b is in fluid communication with the second exhaust plenum 312b.

[0026]

[0033] Each of the exhaust inlet openings 305a and 305b has an inlet width W1. The inlet width W1 is from about 10 mm to about 210 mm, for example from about 45 mm to about 210 mm, for example from about 75 mm to about 175 mm, for example from about 100 mm to about 155 mm. Thus, the inlet width W1 is less than or equal to half of the width of the process region 136.

[0027]

[0034] The exhaust outlet openings 308a and 308b are arranged on the side opposite to the exhaust inlet openings 305a and 305b of the exhaust passage bodies 204a and 204b. Thus, the first exhaust outlet opening 308a is arranged on the second side opposite to the first side of the first exhaust passage body 204a and is in fluid connection with the first exhaust plenum 312a. The second exhaust outlet opening 308b is arranged on the second side opposite to the first side of the second exhaust passage body 204b and is in fluid connection with the second exhaust plenum 312b. The exhaust outlet openings 308a and 308b are smaller in width than the exhaust inlet openings 305a and 305b. The exhaust outlet openings 308a and 308b have an outlet width W2 of from about 15 mm to about 110 mm, for example from about 20 mm to about 100 mm, for example from about 20 mm to about 40 mm. Since the outlet width W2 is smaller than the inlet width W1, a higher concentration of process gas can flow over the growth monitor 310.

[0028]

[0035] The ratio of the inlet width W1 to the outlet width W2 is from about 2:1 to about 20:1, for example from about 3:1 to about 10:1, for example from about 4:1 to about 8:1. The ratio of the inlet width W1 to the outlet width W2 enables sufficient film growth on the growth monitor 310 and reduces the influence of the reduced outlet width W2 on the back pressure and the flow path through the process region 136.

[0029]

[0036] The process gas flowing through the deposition chamber 100 enters the exhaust passage bodies 204a, 204b through the exhaust inlet openings 305a, 305b while in the first flow path 318 before it changes to the second flow path 320 where one or more baffles 304 narrow the exhaust plenums 312a, 312b to the outlet width W2 adjacent to the outlet openings 308a, 308b. The second flow path 320 flows the process gas towards the center line C of the exhaust system, towards one side of the exhaust plenums 312a, 312b, for example, towards the inside of the exhaust plenums 312a, 312b. When the process gas is flowed through the outlet openings 308a, 308b, the path of the process gas changes to the third flow path 322. The third flow path 322 is a condensation flow path. The third flow path 322 is arranged to pass through the collector plenum 316. The collector plenum 316 is a plenum arranged within the exhaust collector 206.

[0030]

[0037] The fin arrays 314 disposed within each of the exhaust passage bodies 204a, 204b are configured to maintain the first flow path 318 passing through at least a portion of the exhaust plenums 312a, 312b. The fin array 314 includes a plurality of fins 302 such that a first plurality of fins 302 are disposed within the first exhaust plenum 312a of the first exhaust passage body 204a. A second plurality of fins 302 are disposed within the second exhaust plenum 312b and the second exhaust passage body 204b. The fin array 314 is configured to maintain good flow control through the process region 136 and extends from a position adjacent to the exhaust inlet openings 305a, 305b.

[0031]

[0038] The number of fins 302 within the fin array 314 may be at least 4 fins 302, for example at least 5 fins 302, for example from 5 fins 302 to about 30 fins 302, for example from 5 fins 302 to about 20 fins 302. The number of fins 302 makes the gap between each adjacent fin 302 smaller and assists in the control of the first flow path 318.

[0032]

[0039] One or more growth monitors 310 are disposed within the fin array 314, for example, between two adjacent fins 302. Two or more growth monitors 310 may be disposed within each fin array 314 of both the first exhaust passage body 204a and the second exhaust passage body 204b. The growth monitors 310 within the fin array 314 can correlate different growth monitors 310 with different positions on the substrate, and thus may be useful for providing measured values of growth rates at different positions on the substrate 102.

[0033]

[0040] Each fin 302 within the fin array 314 is parallel to each other. The fins 302 extend in a direction parallel to the desired first flow path 318 and parallel to the gas flowing out of the injector 202. Other configurations of the fin array 314 are also envisioned. In some embodiments, each fin 302 is of a similar length. In other embodiments, each fin 302 is not necessarily of the same length. For example, the fins 302 closer to the center line C of the process region 136 and the exhaust system 178 are shorter than the fins 302 farther from the center line C.

[0034]

[0041] When the process gas exits the fin array 314, the process gas flows into the main portions 311 of the exhaust plenums 312a, 312b. The main portions 311 of the exhaust plenums 312a, 312b are open spaces and can help reduce the backpressure that would accumulate if the fin array 314 extended up to the baffle plate 304. In some embodiments, there is a gap of at least 5 mm, for example, a gap of about 5 mm to about 40 mm, between the end of the fin array 314 and the closest portion of the baffle plate 304.

[0035]

[0042] The baffle plate 304 extends from the outer surface 328 of each exhaust passage body 204a, 204b toward the inner surface 330 of each exhaust passage body 204a, 204b. The outer surface 328 is the inner surface of the exhaust plenums 312a, 312b that are farthest from the center line C, and the inner surface 330 is the inner surface of the exhaust plenums 312a, 312b that are closest to the center line C. Accordingly, the baffle plate 304 within the first exhaust passage body 204a extends from the outer surface 328 of the first exhaust plenum 312a toward the inner surface 330 of the first exhaust passage plenum 312a or the center line C of the exhaust system 178. The baffle plate 304 within the second exhaust passage body 204b extends from the outer surface 328 of the second exhaust plenum 312b toward the inner surface 330 of the second exhaust passage plenum 312b or the center line C of the exhaust system 178.

[0036]

[0043] The baffle plate 304 extends at an angle φ with respect to the outer surfaces 328 of each exhaust plenum 312a, 312b. The angle φ is the interior angle facing the fin array 314. The angle φ is an obtuse angle, greater than about 90 degrees, for example from about 100 degrees to about 170 degrees, for example from about 100 degrees to about 160 degrees, for example from about 110 degrees to about 145 degrees. The angle at which the baffle plate 304 is disposed helps control the limiting velocity of the exhaust plenums 312a, 312b. The baffle plate 304 is disposed at an angle other than 0 degrees or 90 degrees with respect to the orientation of the fins 302, for example at an angle from about 10 degrees to about 80 degrees with respect to the orientation of the fins 302. The baffle plate 304 extends over more than 50% of the width of each exhaust plenum 312a, 312b, for example over more than 60% of the width of each exhaust plenum 312a, 312b, for example over more than 70% of the width of each exhaust plenum 312a, 312b. In some embodiments, the baffle plate 304 has a radius of curvature defined as the radius from the center of the process region 136 of the deposition chamber 100 to the gas guide surface 332. In some embodiments, the radius of curvature varies across the entire gas guide surface 332, for example the portion closer to the inner surface 330 of the gas guide surface 332 has a smaller radius of curvature. The radius of curvature of the gas guide surface 332 may be other than the radius from the center of the process region 136. Each baffle plate 304 has a gas guide surface 332. The gas guide surface 332 is the main portion 311 of the exhaust plenums 312a, 312b, and the surface of the baffle plate 304 facing the fin array 314.

[0037]

[0044] The baffle plate 304 may have either a curved gas guide surface 332, a straight gas guide surface 332, or a faceted gas guide surface 332. Although the gas guide surface 332 is shown as straight in FIG. 3A, in some embodiments it may be curved such that it follows the perimeter of a circle, ellipse, hyperbola, or parabola. The curved surface may reduce vortices or turbulence within the gas flow path, allowing for better gas flow control. The curvature of the gas guide surface 332 can be varied according to the size of the deposition chamber 100 and the size of the exhaust system 178.

[0038]

[0045] The exhaust outlet openings 308a and 308b are disposed between the innermost portions of the respective baffle plates 304 and the inner surfaces 330 of the respective exhaust plenums 312a and 312b. The first exhaust outlet opening 308a is disposed within the first exhaust plenum 312a and connects the first exhaust plenum 312a to the collector plenum 316. The second exhaust outlet opening 308b is disposed within the second exhaust plenum 312b and connects the second exhaust plenum 312b to the collector plenum 316.

[0039]

[0046] One or more growth monitors 310 are located either within the exhaust outlet openings 308a and 308b or immediately downstream of the exhaust outlet openings 308a and 308b. The first growth monitor 310 is disposed within the first exhaust outlet opening 308a or immediately downstream of the first exhaust outlet opening 308a. The second growth monitor 310 is disposed within the second exhaust outlet opening 308b or immediately downstream of the second exhaust outlet opening 308b. Disposing the growth monitor 310 immediately downstream of the exhaust outlet openings 308a and 308b is defined as disposing the growth monitor 310 within 10 mm from the exhaust outlet openings 308a and 308b and separated from the fin array 314.

[0040]

[0047] The baffle plate 304 narrows the passage through which the exhaust gas passes through the exhaust plenums 312a and 312b, and thus increases the density or concentration of the exhaust gas flowing over the growth monitor 310. The growth monitor 310 is disposed on either the top surface 326 or the bottom surface 327 (FIG. 3B) of the exhaust plenums 312a and 312b such that the growth monitor 310 does not block the third flow path 322 and is instead disposed in a straight line with the third flow path 322. The growth monitor 310 is at least partially located inside the collector plenum 316.

[0041]

[0048] Before the exhaust gas is removed from the exhaust collector 206 through the duct opening 306 (FIG. 3B) of the exhaust duct 323, it passes over the growth monitor 310 and enters the collector plenum 316. Since the width of the collector plenum 316 adjacent to the outlet openings 308a, 308b is wider than the outlet openings 308a, 308b, the width of the collector plenum 316 adjacent to each of the outlet openings 308a, 308b is the same as the inlet width W1, and the total width of the collector plenum 316 is the same as the inlet width W1 or more than twice the inlet width W1.

[0042]

[0049] The duct opening 306 is disposed in a portion of the collector plenum 316 opposite to the outlet openings 308a, 308b. The duct opening 306 is configured to enable the exhaust gas in the exhaust collector 206 to be discharged to the exhaust pump 157 through the exhaust duct 323. Another growth monitor 310 adjacent to the duct opening 306 is provided in the collector plenum 316. The growth monitor 310 adjacent to the duct opening 306 is disposed on the back side wall 321 (FIG. 3B) of the collector plenum 316 that is farthest from the outlet openings 308a, 308b. In some embodiments, the growth monitor 310 may be disposed directly above the duct opening 306 or within the duct opening 306, for example, within the upper portion of the exhaust duct 323.

[0043]

[0050] At least the fins 302 and the baffle plate 304 can be formed from a material having a high thermal conductivity, such as a material having a thermal conductivity of about 100 W / m·°K or more, such as about 150 W / m·°K or more, such as about 175 W / m·°K or more, or can be coated with such materials. The material of the fins 302 is selected to reduce contamination of the deposition chamber 100 while maintaining the temperature of the exhaust gas flowing through the exhaust plenums 312a, 312b before flowing over the growth monitor 310. In some embodiments, at least a portion of the walls forming the exhaust plenums 312a, 312b are coated with a high thermal conductivity material similar to the fins 302 and the baffle plate 304. The interior of the exhaust collector 206 may likewise be coated with a high thermal conductivity material. The high thermal conductivity material may be silicon carbide (SiC). Other suitable high thermal conductivity materials are also envisioned. In some embodiments, the fins 302 and the baffle plate 304 are formed of graphite and coated with silicon carbide. The high thermal conductivity material conducts heat from the process region 136 and reduces the cooling rate of the exhaust gas flowing through the exhaust plenums 312a, 312b. By heating the exhaust gas before flowing it over the growth monitor 310, more stable film formation on the growth monitor 310 becomes possible, and the film growth rate in the process chamber can be estimated more accurately.

[0044]

[0051] FIG. 3B is a cross-sectional side view showing the exhaust system 178 of the deposition chamber 100 of FIG. 1 according to an embodiment of the present disclosure. As shown in FIG. 3B, the exhaust plenums 312a, 312b of the exhaust system 178 extend through at least a portion of the flow module 112 such that the exhaust plenums 312a, 312b extend through the flow module 112. The fins 302 are disposed adjacent to the process region 136.

[0045]

[0052] The fins 302 and the baffle plate 304 extend to the full height of the exhaust plenums 312a, 312b such that the fins 302 and the baffle plate 304 extend between the top surface 326 and the bottom surface 327 of the exhaust plenums 312a, 312b. The growth monitors within the fin array 314 are disposed on the top surface 326.

[0046]

[0053] The exhaust collector 206 is connected to the backside end of the exhaust system 178. The exhaust collector 206 includes a top surface 328, a bottom surface 327, and a backside sidewall 324. The growth monitors 310 immediately downstream of the exhaust outlet openings 308a, 308b are positioned on the top surface 328 of the collector plenum 316 within the exhaust collector 206. Another growth monitor 310 is disposed on the backside sidewall 321 of the collector plenum 316. The positioning of the growth monitors 310 enables accurate measurement of the film growth rate by each growth monitor 310. By mapping the measurements from each growth monitor 310, differences in the growth rate across different positions of the substrate 102 can be seen.

[0047]

[0054] The conduit opening 306 is disposed through the bottom surface 327 of the collector plenum 316 and opens into the exhaust conduit 323. The exhaust conduit 323 extends downward from the conduit opening 306 and is fluidly connected to the exhaust pump 157. Another growth monitor 310 can be disposed on the inner wall of the exhaust conduit 323 downstream of the growth monitor 310 on the backside sidewall 321 of the collector plenum 316.

[0048]

[0055] In some embodiments, more or fewer growth monitors 310 can be used within the exhaust system 178. In some embodiments, only the growth monitors 310 adjacent to the exhaust outlet openings 308a, 308b are disposed within the exhaust system 178. In other embodiments, the growth monitors 310 adjacent to the exhaust outlet openings 308a, 308b can be a single growth monitor 310. In still other embodiments, the growth monitors 310 adjacent to the exhaust outlet openings 308a, 308b and the growth monitors 310 on the backside sidewall 321 of the collector plenum 316 are used.

[0049]

[0056] Figures 4A and 4B are diagrams showing a growth monitor 310 for use within the deposition chamber 100 of FIG. 1 according to an embodiment of the present disclosure. The growth monitor 310 is a parametric resonance sensor including a shuttle mass 402, an electrostatic actuator 404, an amplitude and / or velocity sensor 406, a plurality of anchors 408, and a plurality of beams 410. The shuttle mass 402 is one or more of a silicon-containing material, bulk titanium, and electroplated nickel.

[0050]

[0057] The shuttle mass 402 further includes a first finger set 420 and a third finger set 424. The electrostatic actuator 404 further includes a second finger set 422. In one embodiment, the amplitude and / or velocity sensor 406 is a capacitor sensor. The capacitance sensor 406 further includes a fourth finger set 426. The first through fourth finger sets 420, 422, 424, and 426 may be an accelerometer, a gyroscope, or other similar systems. The growth monitor 310 is further coupled to a potential source 412 capable of applying a voltage to the electrostatic actuator 404. The potential source 412 is further configured (or may include a ground) to function as a ground for connection to one of the plurality of anchors 408. The plurality of beams 410 are configured to couple the shuttle mass 402 to the anchors 408 such that the anchors 408 secure the shuttle mass 402 to the exhaust collector 206. In one example, the amplitude and / or velocity sensor 406 may alternatively or additionally be a frequency sensor.

[0051]

[0058] During operation, the first finger set 420 is spaced from the second finger set 422, and the third finger set 424 is spaced from the fourth finger set 426. In one embodiment shown in FIG. 4A, the spaced relationship of the finger sets is an interdigitated configuration, i.e., the first finger set 420 and the second finger set 422 are interconnected, and the third finger set 424 and the fourth finger set 426 are interconnected. In yet another embodiment, the spaced relationship is an interdigitated curved secondary comb-shaped finger configuration. When the potential source 412 biases the electrostatic actuator 404, the electrostatic actuator 404 is configured to operate the shuttle mass 402 at an operating frequency. The input bias operates the shuttle mass 402 over a frequency range near the parametric resonance instability frequency. The bias is applied across the first finger set 420 and the second finger set 422 to cancel the normal forces on both sides of each finger of the finger sets. However, the lateral force causes the first finger set 420 to operate parallel to the second finger set 422, thus operating the shuttle mass 402. In one embodiment, the operation is translational. In another embodiment, the operation is rotational. In another embodiment shown in FIG. 4B, the spaced relationship of the finger sets is a non-interdigitated comb-shaped finger configuration. The shuttle mass 402 is fixed in place by an anchor 408 via a plurality of beams 410. The plurality of beams 410 are configured to resist the operation of the shuttle mass 402. When the shuttle mass 402 moves relative to the electrostatic actuator 404 due to the force between the first finger set 420 and the second finger set 422, the plurality of beams 410 function as springs to return the shuttle mass 402 to its original position. The third finger set 424 is configured to move parallel to the fourth finger set 426 as a result of the operation of the shuttle mass 402. The capacitance sensor is configured to measure a change in the parametric resonance instability frequency by measuring the operating amplitude and / or velocity of the shuttle mass 402.The frequency value at which the amplitude increases significantly at the unstable frequency is accurately known. As the mass of the shuttle mass 402 increases, the transition frequency changes. By tracking the transition frequency, the thickness of the material deposited on the growth monitor 310 can be measured, as further explained below.

[0052]

[0059] The parametric resonance sensor measures the frequency shift at the resonance stability boundary to monitor the mass change of the shuttle mass 402. The amplitude and / or velocity transitions at the resonance stability boundary are very sharp, which makes small frequency changes easily detectable and results in a high frequency shift resolution. The advantage of the parametric resonance sensor is that the sharpness of the boundary does not depend on the quality factor (Q). Therefore, very small mass changes can be detected not only at atmospheric pressure but also in high-pressure environments.

[0053]

[0060] In contrast, mass sensing devices based on simple harmonic resonance, such as quartz crystal microbalances (QCMs), are limited by their ability to detect small frequency changes described by the quality factor (Q). The minimum detectable mass change using SHR is directly proportional to the minimum detectable frequency change, which is inversely proportional to the Q factor. Therefore, in applications for monitoring epitaxial mass deposition where typical pressures range from 5 Torr to 760 Torr, the minimum detectable mass change becomes significantly higher. This limits the range of processes for which QCM-based sensing can be used for monitoring. However, the parametric resonance sensor of the present disclosure has a much wider process window than sensing devices based on simple harmonic resonance, enabling more accurate monitoring and detection, particularly in high-pressure and / or epitaxial deposition processes.

[0054]

[0061] As exhaust gas flows through exhaust system 178, unreacted precursor gas present in the reaction by-products deposits on growth monitor 310. Using the voltage applied by potential source 412, shuttle mass 402 is actuated. In the vicinity of the parametric instability region, a periodic sweep over a small frequency range is performed. Beyond the instability region, the vibration amplitude changes abruptly. In one embodiment, the capacitance sensor measures the vibration amplitude when the capacitance between shuttle mass 402 and the capacitance sensor changes due to a shift in the position of third finger set 424 relative to fourth finger set 426. The frequency at which this occurs is recorded and compared to the value from the last frequency sweep. The change in frequency is related to the change in mass. Through prior calibration, the change in mass due to condensation on shuttle mass 402 is related to the thickness deposited on substrate 102. This enables in-situ and real-time measurement of the deposition on substrate 102.

[0055]

[0062] In another embodiment, the amplitude and / or velocity sensor 406 is a laser Doppler vibrometer. The laser Doppler vibrometer is configured to measure light reflected from the shuttle mass 402 in order to characterize the operating amplitude and / or velocity of the shuttle mass. The vibration amplitude is measured using the laser Doppler vibrometer. In one embodiment, the laser Doppler vibrometer amplitude and / or velocity sensor has a built-in 45-degree mirror. The mirror can be cut by a focused ion beam after device manufacture. Laser light is directed at the mirror and reflected onto the shuttle mass 402. Reflected light from the shuttle mass 402 is measured in order to characterize the operating amplitude and / or velocity of the shuttle mass 402. When the mass of the shuttle mass 402 increases due to the deposition of exhaust gas, the measured value of the reflected light changes. The laser Doppler vibrometer measures the amplitude and / or velocity and indirectly measures the change in the parametric resonance frequency by paying attention to the frequency at which the transition to large amplitude vibrations begins. By tracking this change in the parametric resonance frequency over time due to the increase in the mass of the shuttle mass 402, the thickness of the material deposited on the growth monitor 310 can be determined. By prior calibration, the change in mass due to condensation on the shuttle mass is related to the thickness deposited on the substrate 102.

[0056]

[0063] Since the growth monitor 310 is configured to be disposed within the deposition chamber 100, it is subject to the influence of reactive process chemicals within the exhaust system 178. The materials of the protective coating, as well as the anchor 408, the plurality of beams 410, and the shuttle mass 402, affect the reactivity of the growth monitor 310 with the process chemicals within the deposition chamber 100. Accordingly, a material composition is selected that allows for accurate film thickness measurement on the growth monitor 310 while reducing the reactivity of the growth monitor 310 with the process chemicals within the deposition chamber 100.

[0057]

[0064] The protective coating is formed from one of silicon oxides such as alumina (Al2O3) or silicon dioxide (SiO2). The protective coating is formed from a material that does not deteriorate even when exposed to epitaxial deposition process conditions or process gases. The protective coating may be a cover lens or a coating applied to the shuttle mass 402. The protective coating has a thickness of less than about 10 μm, for example, from about 1 nm to about 10 nm, for example, from about 1 nm to about 5 nm. The thin thickness can protect the growth monitor 310 without significantly attenuating the operation of the shuttle mass 402.

[0058]

[0065] Figure 5 is a schematic control diagram 500 for use within the deposition chamber 100 of FIG. 1 according to an embodiment of the present disclosure. The controller 120 is configured to receive data or input as sensor readings 502 from each growth monitor 310. The controller 120 comprises or communicates with a system model 506 of the deposition chamber 100. The system model 506 includes a heating model and a gas flow module. The system model 506 is a program configured to estimate the gas flow and heating within the deposition chamber 100 during the deposition process. The controller 120 is further configured to store the readings and calculated values 504.

[0059]

[0066] The readings and calculated values 504 include not only the previous sensor readings 502 but also any other previous sensor readings within the deposition chamber 100. The readings and calculated values 504 further include stored calculated values since the sensor readings 502 were measured by the controller 120 and executed through the system model 506. Thus, the controller 120 is configured to retrieve the stored readings and calculated values 504 and at the same time save the readings and calculated values 504 for future use. By maintaining the previous readings and calculated values, the controller 120 can adjust the system model 506 over time to reflect a more accurate version of the deposition chamber 100.

[0060]

[0067] In the embodiments described in this specification, the controller 120 includes a programmable central processing unit (CPU) that operates with a memory and a mass storage device, an input control device, and a display device (not shown). The controller 120 monitors the flow of precursors, process gases, and purge gases. The support circuitry is coupled to the CPU to support the processor in a conventional manner. In some embodiments, the controller 120 includes a plurality of controllers 120 such that the stored read and calculated values 504 and the system model 506 are stored in a controller separate from the controller 120 that operates the deposition chamber 100. In other embodiments, all of the system model 506 and the stored read and calculated values 504 are stored within the controller 120.

[0061]

[0068] The controller 120 is configured to control the heating and gas flow within the deposition chamber 100 by controlling the operation of the lamp and gas flow controller 508. The lamp and gas flow controller 508 includes an upper lamp 141, a lower lamp 143, a process gas source 151, a purge gas source 162, and an exhaust pump 157. The controller 120 can also control the operating assembly 121 within the deposition chamber 100.

[0062]

[0069] The controller 120 is configured to adjust the output to each of the lamp and gas flow controllers 508 based on the sensor readings 502, the system model 506, and the stored read and calculated values 504. The controller 120 includes embedded software and correction algorithms for calibrating the frequency shift of the growth monitor 310 to the film thickness on the substrate 102. The film thickness on the substrate 102 can be measured when the substrate 102 exits the deposition chamber or during a process step to provide a reference for the film thickness growth rate measured using the growth monitor 310. The controller 120 may include a machine learning algorithm and can use regression or clustering techniques. The algorithm can be an unsupervised algorithm or a supervised algorithm.

[0063]

[0070] FIG. 6 is a diagram showing a method 600 for adjusting process conditions in the deposition chamber 100 of FIG. 1 according to an embodiment of the present disclosure. The method 600 uses a growth monitor 310 in the deposition chamber 100 and a controller 120 described herein to improve film thickness uniformity and characteristics across the substrate 102.

[0064]

[0071] During the method 600, during step 602, a first substrate is processed in a processing chamber. The first substrate may be the substrate 102, and the processing chamber may be the deposition chamber 100. Processing the first substrate during step 602 includes performing a deposition process such as an epitaxial deposition process on the first substrate. The deposition process includes growing a film on the first substrate and heating the substrate using the upper lamp 141 and the lower lamp 143. Gas is flowed into the process region 136 from the process gas inlet 114 and the purge gas inlet 164 before being removed through the exhaust gas outlet 116.

[0065]

[0072] While the first substrate is being processed in the processing chamber, during another step 604, the growth monitor 310 is used to measure film thickness growth on the monitor. The measurement of film thickness growth on the growth monitor 310 is performed as a rolling process. A controller, such as the controller 120, is configured to receive an input from the combination of growth monitors 310 described with respect to FIGS. 3A - 3B. This input is used to estimate film growth on the first substrate. When the first substrate has finished being processed in the processing chamber, during another step 606, the film thickness can be measured using one or more other non-contact sensors in the processing chamber or an adjacent chamber. The measurement of film growth on the first substrate during step 606 is performed by a non-destructive method such as using one or more non-contact sensors. The non-contact sensor may be a laser thickness gauge and can perform a plurality of individual measurements across the surface of the first substrate or scan the length of the first substrate.

[0066]

[0073] The non-contact sensor used in process 606 is not necessarily used for film thickness measurement during substrate processing because radiation from the process gas and heat source interferes with the sensor readings, reducing the reading sensitivity and accuracy. Therefore, the growth monitor 310 enables adjustment of process conditions such as heating and gas flow while the first substrate is being processed. Using the measurement values obtained with the non-contact sensor, the correlation between film formation on one or more growth monitors 310 and film formation on the substrate can be updated or confirmed. Thus, the measurement using the non-contact sensor is optional and can be omitted.

[0067]

[0074] Measurement of film growth on the first substrate enables calculation of the growth rate on the first substrate during another process 608. Calculating the growth rate on the first substrate during process 608 verifies the accuracy of the model used in the controller and enables adjustment of the process chamber model during another process 610 to achieve a predetermined film growth on the substrate during processing. Adjusting the process chamber model during process 610 enables better use of the growth monitor 310 in a specific process. Once the model is adjusted, processing of another substrate such as the second substrate is executed, and processes 602 to 610 are repeated. To continuously adjust the accuracy of the process chamber model 610 and improve the film thickness growth results, process 602 can be looped. If preventive maintenance is performed on the process chamber, the process chamber model can be reset or adjusted to restart method 600. Therefore, the film thickness results are continuously improved between each substrate. This further enables an accurate film thickness and overcomes changes due to film accumulation on the surface within the process area and changes in the process chamber characteristics due to the aging of the lamp.

[0068]

[0075] FIG. 7 is a diagram showing a method 700 using the growth monitor 310 according to the embodiment. In step 702, the shuttle mass 402 is actuated by an electrostatic force from the electrostatic actuator. In step 704, the frequency range near the parametric resonance instability boundary of the shuttle mass 402 is swept. In step 706, exhaust gas is deposited on the shuttle mass 402 to rapidly change the vibration amplitude of the shuttle mass 402. The frequency values are recorded by the controller 120. In step 708, the current value of the instability frequency is compared with the previous value of the instability frequency. The difference in values corresponds to the mass change of the shuttle mass 402 due to the deposition of the exhaust gas. The correspondence between the instability frequencies (and the changes between them) and the associated mass can be determined empirically and stored in a data table accessible by the controller. In step 710, the controller 120 outputs the thickness value to the user. The thickness value is calculated using a previous calibration that associates the mass change of the shuttle mass 402 with the thickness increase on the substrate 102. In step 712, the frequency range near the parametric resonance boundary is periodically swept to continuously monitor the thickness change on the shuttle mass 402.

[0069]

[0076] While the foregoing is directed to embodiments of the present disclosure, it is possible to devise additional embodiments of the present disclosure without departing from the basic scope thereof as determined by the following claims.

Claims

1. An exhaust system for substrate processing, comprising: a first exhaust plenum; a first exhaust inlet opening fluidly connected to the first exhaust plenum; a first plurality of fins disposed in the first exhaust plenum adjacent to the first exhaust inlet opening; a first exhaust outlet opening fluidly connected to the first exhaust plenum; a first baffle plate disposed adjacent to the first exhaust outlet opening and configured to narrow the width of the first exhaust plenum; at least one growth monitor disposed downstream of the first baffle plate and configured to measure the thickness of a material deposited on a growth monitor, the at least one growth monitor being a parametric resonance sensor; An exhaust system comprising the above components.

2. The parametric resonance sensor comprises: a shuttle mass; an electrostatic actuator configured to operate the shuttle mass at an operating frequency; an amplitude and / or velocity sensor configured to measure a change in the operating amplitude and / or velocity of the shuttle mass; a plurality of anchors; a plurality of beams configured to couple the plurality of anchors to the shuttle mass and to resist the operation of the shuttle mass. The exhaust system according to claim 1, comprising the above components.

3. The exhaust system according to claim 2, wherein the shuttle mass comprises one or more of a silicon-containing material, bulk titanium, and electroplated nickel.

4. The exhaust system according to claim 2, wherein the shuttle mass further comprises a first finger set, the electrostatic actuator further comprises a second finger set, and the first finger set is configured to operate in parallel with the second finger set.

5. The exhaust system according to claim 4, wherein the shuttle mass further comprises a third finger set, the amplitude and / or velocity sensor is a capacitance sensor, the capacitance sensor further comprises a fourth finger set, and the third finger set is configured to move in parallel with the fourth finger set as a result of the operation of the shuttle mass.

6. The exhaust system according to claim 5, wherein the capacitance sensor measures a change in the parametric resonance frequency when the mass of the shuttle mass increases and determines the thickness of the material deposited on the growth monitor.

7. The exhaust system according to claim 4, wherein the amplitude and / or velocity sensor is a laser Doppler vibrometer configured to measure light reflected from the shuttle mass in order to track changes in the resonance frequency of the shuttle mass.

8. The exhaust system according to claim 7, wherein the laser Doppler vibrometer measures changes in the operating amplitude and / or velocity when the mass of the shuttle mass increases and determines the thickness of the material deposited on the growth monitor.

9. A processing system suitable for semiconductor substrate processing, a chamber body forming a process region, a substrate support disposed within the process region of the chamber body, an upper window disposed above the substrate support, a lower window disposed below the substrate support, wherein the upper window and the lower window further define the process region, the lower window, an injector disposed through one side surface of the chamber body and configured to introduce process gas into the process region, An exhaust system including at least one growth monitor disposed through a second side surface of the chamber body opposite to the injector and configured to measure the thickness of the material deposited on the growth monitor, wherein the growth monitor is a parametric resonance sensor, the exhaust system comprising a processing system.

10. The parametric resonance sensor includes a shuttle mass, an electrostatic actuator configured to operate the shuttle mass at an operating frequency, an amplitude and / or velocity sensor configured to measure changes in the operation of the shuttle mass, a plurality of anchors configured to be coupled to the exhaust system, a plurality of beams configured to couple the plurality of anchors to the shuttle mass and resist the operation of the shuttle mass, The processing system according to claim 9, comprising.

11. The processing system according to claim 10, wherein the shuttle mass includes one or more of a silicon-containing material, bulk titanium, and electroplated nickel.

12. The processing system according to claim 10, wherein the shuttle mass further includes a protective coating, and the protective coating is one of alumina or silicon dioxide.

13. The at least one growth monitor communicates with a controller configured to determine a growth rate on the growth monitor and adjust at least one of a process gas flow rate, a heating energy level, or an exhaust flow rate in response to the determined growth rate, the processing system of claim 9.

14. The processing system of claim 10, further comprising a controller, the controller comparing a measured growth rate on the growth monitor, a chamber thermal model, a chamber flow model, and previous monitor measurements to determine an adjustment to at least one of a process gas flow rate, a heating energy level, or an exhaust flow rate.

15. A controller for a process system, which when executed by a processor, causes the system to process a substrate in a processing chamber by flowing a process gas from a process gas inlet into the process region, depositing the gas on the substrate, and exhausting the process gas through an exhaust system, the exhaust system further including a growth monitor, the growth monitor including a parametric resonance sensor; deposit the process gas on the growth monitor; measure film growth on the growth monitor; calculate a film growth rate on the substrate; and adjust processing chamber parameters and stores instructions for causing the controller to perform the above operations.

16. The controller of claim 15, further operating a shuttle mass with respect to an amplitude and / or velocity sensor.

17. The controller of claim 16, further causing the system to sweep over a frequency range near a parametric resonance instability boundary of the shuttle mass at a first time interval and a second time interval to determine a parametric resonance instability frequency of the shuttle mass.

18. The controller of claim 17, further causing the system to compare a value of the parametric instability frequency of the shuttle mass at a first time interval with a value of the parametric instability frequency of the shuttle mass at a second time interval to output film growth on the substrate using processing chamber parameters.

19. The controller according to claim 18, which adjusts at least one of a process gas flow rate, a heating energy level, or an exhaust flow rate in response to a calculated film growth rate on a substrate.

20. The controller according to claim 19, which compares a growth rate on a measured growth monitor, a chamber heat model, a chamber flow rate model, and previous monitor measurements to determine an adjustment to at least one of a process gas flow rate, a heating energy level, or an exhaust flow rate.

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