Growth monitoring systems and methods for film deposition

Abstract

The present disclosure generally relates to process chambers for semiconductor processing. In one embodiment, a growth monitor for substrate processing is provided. The growth monitor comprises a sensor holder and a crystal disposed in the sensor holder, the crystal having a front side and a back side. An opening exposing the front side of the crystal is formed in the sensor holder. A gas inlet is disposed through the sensor holder to the back side of the crystal and to a plenum formed by the sensor holder. A gas outlet is fluidly coupled to the plenum.

Description

Technology Field

[0001] The embodiments of the present disclosure generally relate to apparatuses and methods for manufacturing semiconductor devices. More specifically, the apparatus disclosed herein relates to exhaust assemblies and growth rate sensors within a semiconductor process chamber. Methods of using these are also disclosed. Background Technology

[0002] Semiconductor substrates are processed for a wide variety of applications, including the manufacturing 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 rotatable around a central axis. Precise control of the heating source is desirable to heat the substrate uniformly within tight tolerances. The temperature of the substrate can affect the uniformity of the material deposited on it.

[0003] The ability to precisely control substrate temperatures within a process chamber has a significant impact on throughput and production yields. Conventional process chambers struggle to meet the temperature control standards required to manufacture next-generation devices while meeting the growing demand for improved production yields and faster throughput. During processing, process gases flow across the process volume within the process chamber. Process gases flow parallel to the substrate surface from one side of the process chamber to the opposite side. Heating and gas flow within the process chamber can be adjusted to improve film deposition rates across the substrates. Current sensors within the process chamber have a limited lifespan, which results in downtime in addition to the routine preventive maintenance downtimes of the process chambers. These additional downtimes increase the cost of ownership. Substrates processed between calibration and measurement operations also exhibit less precise deposition rates due to variations in chamber conditions.

[0004] Therefore, there is a need for a sensor assembly and method for monitoring the growth rate.

[0005] The present disclosure generally relates to process chambers for semiconductor processing. In one embodiment, a growth monitor for substrate processing is provided. The growth monitor comprises a sensor holder and a crystal disposed in the sensor holder, wherein the crystal has a front side and a back side. An opening exposing the front side of the crystal is formed in the sensor holder. A gas inlet is disposed through the sensor holder to the back side of the crystal and to a plenum formed by the sensor holder. A gas outlet is fluidly coupled to the plenum.

[0006] In another embodiment, a method for substrate processing is provided. The method includes the step of measuring film characteristics. The method includes the step of flowing a process gas over a growth monitor having a crystal. The method includes the step of flowing a back gas over the back of the crystal. The method includes the step of purging the front of the crystal using a front purge gas. The method includes the step of measuring the characteristics of the process gas using the crystal, wherein the step of measuring the characteristics of the process gas occurs when the front of the crystal is not being purged.

[0007] In another embodiment, an exhaust passage body for substrate processing is provided. The exhaust passage body includes an exhaust plenum. An exhaust inlet opening is formed through a first end of the exhaust passage body and is fluidically connected to the exhaust plenum. A plurality of fins are disposed adjacent to the exhaust inlet opening within the exhaust plenum. An exhaust outlet opening is formed through a second end of the exhaust passage body and is fluidly connected to the exhaust plenum. At least one growth monitor is disposed adjacent to the exhaust outlet opening and is configured to measure the thickness of a material deposited on the growth monitor. The at least one growth monitor includes a sensor holder and a crystal disposed in the sensor holder, the crystal having a front side and a back side. An opening exposing the front side of the crystal is formed in the sensor holder. A gas inlet is disposed through the sensor holder to the back side of the crystal and to the plenum formed by the sensor holder. A gas outlet is fluidly coupled to the plenum. Brief explanation of the drawing

[0008] In a manner that the features listed above of the present disclosure can be understood in detail, a more specific description of the present disclosure, which has been briefly summarized above, may be made with reference to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings are merely illustrative of exemplary embodiments and should not be construed as limiting the scope, as the present disclosure may allow for other equally valid embodiments.

[0009] FIG. 1 is a schematic example of a deposition chamber according to embodiments of the present disclosure.

[0010] FIG. 2 illustrates a cross-sectional plan view of the deposition chamber of FIG. 1 according to embodiments of the present disclosure.

[0011] FIG. 3a illustrates a cross-sectional plan view of an exhaust system of a deposition chamber of FIG. 1 according to embodiments of the present disclosure.

[0012] FIG. 3b illustrates a side cross-sectional view of an exhaust system of a deposition chamber of FIG. 1 according to embodiments of the present disclosure.

[0013] FIG. 4a illustrates a growth monitor for use in the deposition chamber of FIG. 1 according to embodiments of the present disclosure.

[0014] FIG. 4b illustrates a growth monitor for use in the deposition chamber of FIG. 1 according to embodiments of the present disclosure.

[0015] FIG. 5 illustrates a block flow diagram of a method for monitoring membrane growth according to embodiments of the present disclosure.

[0016] FIG. 6 illustrates a schematic diagram of a control for use in the deposition chamber of FIG. 1, according to embodiments of the present disclosure.

[0017] FIG. 7 illustrates a method for adjusting process conditions within the deposition chamber of FIG. 1 according to embodiments of the present disclosure.

[0018] For ease of understanding, the same reference numbers have been used where possible to designate the same elements common to the drawings. It is considered that the elements and features of one embodiment may be beneficially incorporated into other embodiments without further mention. Specific details for implementing the invention

[0019] The present disclosure relates to growth rate sensors in a semiconductor process chamber. The growth rate sensors are quartz crystal film thickness monitors and enable the measurement of film thickness on the growth rate sensors. The film thickness on the growth rate sensors is used to calculate the growth rate on a substrate in the process chamber. The thickness measurements are used to adjust one or more process controls within the process volume of the process chamber and to improve film growth across the substrate.

[0020] Crystal monitors include components that can be sensitive to process temperature and may react with process chemistry to cause corrosion. However, crystal monitors as described herein are configured to reduce reactions with epitaxial deposition process chemistry that could adversely affect sensor performance, sensor life, or process conditions within the process chamber. Flowing purge gases over the components of the crystal monitors reduces the reaction of the crystal with process chemistry, removes any debris from the components of the crystal monitors, and maintains temperature conditions. It has been found that continuously flowing purge gases over the back surface of the crystal efficiently controls the temperature of the crystal while keeping the back surface and electrical connections clean. Additionally, the methods described herein provide for flowing purge gases over the front surface of the crystal while the crystal monitor is sampling and performing measurements. Purging the entire surface area of ​​the quartz crystal without being bound by theory is also believed to enable improved temperature control and remove deposited gases from the quartz crystal, thereby extending the lifespan of the quartz crystal.

[0021] The location and number of quartz crystal monitors provide increased sensitivity and sensor life cycles. The configuration of the exhaust system around the quartz crystal monitors further enables the gas flow within the process volume to remain constant or have minimal flow effects, while increasing the process gas flow across the quartz crystal monitors to improve the growth rate on the quartz crystal monitors.

[0022] Software algorithms within the process chamber controller improve film thickness growth rates by measuring growth rates from crystal monitors and enabling calibration of process conditions within the process chamber as well as other sensors within the process chamber.

[0023] FIG. 1 is a schematic example of a deposition chamber (100) according to embodiments of the present disclosure. The deposition chamber (100) is an epitaxial deposition chamber. The deposition chamber (100) is utilized to grow an epitaxial film on a substrate, such as a substrate (102). The deposition chamber (100) generates a cross-flow of precursors across the uppermost surface (150) of the substrate (102).

[0024] The deposition chamber (100) includes an upper body (156), a lower body (148) positioned below the upper body (156), and a flow module (112) positioned 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. 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) are positioned within the chamber body. As illustrated, a controller (120) communicates with the deposition chamber (100) and is used to control processes such as those described herein. The substrate support (106) is positioned between the upper window (108) and the lower window (110). A plurality of upper lamps (141) are positioned between the upper window (108) and the cover (154). A plurality of upper lamps (141) form a part of the upper lamp module (155). The cover (154) may include a plurality of sensors (not shown) disposed on the cover (154) for measuring the temperature inside the deposition chamber (100). A plurality of lower lamps (143) are disposed between the lower window (110) and the floor (152). A plurality of lower lamps (143) form a part of the lower lamp module (145). The upper window (108) is an upper dome and is formed of an energy-transmitting material, such as crystal. The lower window (110) is a lower dome and is formed of an energy-transmitting material, such as crystal.

[0025] A process volume (136) is formed between the upper window (108) and the lower window (110). The process volume (136) has a substrate support (106) disposed within the process volume (136). The substrate support (106) includes an upper surface, and a substrate (102) is disposed on the upper surface. The substrate support (106) is attached to a shaft (118). The shaft is connected to a motion assembly (121). The motion 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 volume (136).

[0026] The substrate support (106) may include lift pin holes (107) disposed within the substrate support (106). The lift pin holes (107) are sized to accommodate lift pins (132) for lifting the substrate (102) from the substrate support (106) before or after the deposition process is performed. The lift pins (132) may be placed on lift pin stops (134) when the substrate support (106) is lowered from the process position to the transfer position.

[0027] 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 positioned on the side of the flow module (112) opposite to the one or more exhaust gas outlets (116). One or more flow guides are positioned below the plurality of process gas inlets (114) and one or more exhaust gas outlets (116). The flow guides are positioned above the purge gas inlets (164). A liner (163) is positioned on the inner surface of the flow module (112) to protect the flow module (112) from reactive gases used during deposition processes. Process gas inlets (114) and purge gas inlets (164) are positioned to flow gas parallel to the top surface (150) of the substrate (102) placed within the process volume (136). The process gas inlets (114) are fluidically 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).

[0028] One or more exhaust gas outlets (116) are additionally connected to or include an exhaust system. The exhaust system fluidically connects one or more exhaust gas outlets (116) and an exhaust pump (157). An exhaust system as described herein includes one or more growth monitors (310) (Fig. 3a) and is configured to assist in the controlled deposition of a layer on a substrate (102).

[0029] FIG. 2 illustrates a cross-sectional plan view of the deposition chamber (100) of FIG. 1 according to embodiments of the present disclosure. The deposition chamber (100) includes an injector (202) positioned opposite an exhaust system (178). The injector (202) includes process gas inlets (114) and is fluidly coupled to a process gas source (151). The injector (202) may be positioned through at least a portion of the flow module (112) or may be part of the flow module (112). The exhaust system (178) is positioned on the side opposite the process volume (136) from the injector (202). The exhaust system (178) is formed through the flow module, attached to the flow module, or is part of the flow module.

[0030] The exhaust system (178) further comprises at least one exhaust passage body (204a, 204b). The exhaust passage bodies (204a, 204b) form an exhaust path for gases leaving the process volume (136) before entering the exhaust collector (206). As illustrated in FIG. 2, a first exhaust passage body (204a) and a second exhaust passage body (204b) exist. 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, more or fewer exhaust passage bodies (204a, 204b) may exist. In some embodiments, only one exhaust passage body exists, and accordingly, the two exhaust passage bodies (204a, 204b) are merged into a single body.

[0031] Both the first exhaust passage body (204a) and the second exhaust passage body (204b) are coupled to an exhaust collector (206) on the opposite end of the exhaust passage bodies (204a, 204b) from the process volume (136). The exhaust collector (206) is configured to collect exhaust from the first exhaust passage body (204a) and the second exhaust passage body (204b). As the exhaust collector (206) extends away from the exhaust passage bodies (204a, 204b), the exhaust collector (206) narrows.

[0032] FIG. 3a illustrates a cross-sectional plan view of an exhaust system (178) of a deposition chamber (100) of FIG. 1 according to embodiments of the present disclosure. The exhaust system (178) is configured to control the flow of exhaust gases exiting the process volume (136) before flowing over one or more growth monitors (310). To enable the narrowing of the exhaust passage bodies (204a, 204b) while reducing the effect of narrowing on the flow path of process gases through the process volume (136), a fin array (314) and one or more baffles (304) are positioned within each of the exhaust passage bodies (204a, 204b).

[0033] When the process gas flows out of the process volume (136) and into the exhaust system (178), the process gas flows in the first flow path (318). The first flow path (318) is mainly parallel to the gas flow to the surface of the substrate (102) and out of the injector (202). The process gas flows into the exhaust system (178) through exhaust inlet openings (305a, 305b) arranged through each of the exhaust passage bodies (204a, 204b). Thus, the first exhaust inlet opening (305a) is arranged through the first end of the first exhaust passage body (204a), while the second exhaust inlet opening (305b) is arranged through the first end of the second exhaust passage body (204b). The exhaust inlet openings (305a, 305b) are fluidly connected to the exhaust plenums (312a, 312b). The exhaust plenums (312a, 312b) are disposed within each of the exhaust passage bodies (204a, 204b). Thus, 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).

[0034] Exhaust outlet openings (308a, 308b) are positioned on the side opposite to the exhaust passage bodies (204a, 204b) from the exhaust inlet openings (305a, 305b). Thus, a first exhaust outlet opening (308a), which is opposite the first side and fluidly communicates with the first exhaust plenum (312a), is positioned on the second side of the first exhaust passage body (204a). A second exhaust outlet opening (308b), which is opposite the first side and fluidly communicates with the second exhaust plenum (312b), is positioned on the second side of the second exhaust passage body (204b). The exhaust outlet openings (308a, 308b) are narrower than the exhaust inlet openings (305a, 305b).

[0035] Process gases flowing through the deposition chamber (100) enter the exhaust passage bodies (204a, 204b) through the exhaust inlet openings (305a, 305b) while in the first flow path (318) before changing to the second flow path (320) as one or more baffles (304) narrow the exhaust plenums (312a, 312b) adjacent to the outlet openings (308a, 308b). The second flow path (320) brings the process gases toward the center line (C) of the exhaust system and toward one side of the exhaust plenums (312a, 312b), e.g., the inner side of the exhaust plenums (312a, 312b). Once the process gases flow through the outlet openings (308a, 308b), the path of the process gases changes to a third flow path (322). The third flow path (322) is a condensed flow path. The third flow path (322) is placed through a collector plenum (316). The collector plenum (316) is a plenum placed within the exhaust collector (206).

[0036] A fin array (314) disposed within each of the exhaust passage bodies (204a, 204b) is configured to maintain a first flow path (318) through at least a portion of the exhaust plenums (312a, 312b). The fin array (314) comprises a plurality of fins (302), and accordingly, a first plurality of fins (302) is disposed within the first exhaust plenum (312a) of the first exhaust passage body (204a). A second plurality of fins (302) is disposed within the second exhaust plenum (312b) and the second exhaust passage body (204b). The fin array (314) is configured to maintain flow control through the process volume (136) and to extend from a position adjacent to the exhaust inlet openings (305a, 305b).

[0037] One or more growth monitors (310) are placed within the pin arrays (314), for example, between two adjacent pins (302). Two or more growth monitors (310) may be placed within each pin array (314) of both the first exhaust passage body (204a) and the second exhaust passage body (204b). The growth monitors (310) within the pin arrays (314) may assist in providing measurements of the growth rate at different radial positions on the substrate (102).

[0038] Each of the fins (302) within the fin arrays (314) is parallel to one another. 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 arrays (314) are considered.

[0039] Once the process gases leave the fin arrays (314), the process gases flow into the main part (311) of the exhaust plenums (312a, 312b). The main part (311) of the exhaust plenums (312a, 312b) is an open space and can help reduce the backpressure that would accumulate if the fin arrays (314) extended all the way to the baffle plate (304).

[0040] The baffle plate (304) extends from the outer surface (328) of each of the exhaust passage bodies (204a, 204b) toward the inner surface (330) of each of the exhaust passage bodies (204a, 204b). The outer surface (328) is the inner surface of the exhaust plenums (312a, 312b) furthest from the center line (C). The inner surface (330) is the inner surface of the exhaust plenums (312a, 312b) closest to the center line (C). Thus, the baffle plate (304) in 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) in 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 centerline (C) of the exhaust system (178).

[0041] Exhaust outlet openings (308a, 308b) are positioned between the innermost portion of each of the baffle plates (304) and the inner surface (330) of each of the exhaust plenums (312a, 312b). The first exhaust outlet opening (308a) is positioned 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 positioned within the second exhaust plenum (312b) and connects the second exhaust plenum (312b) to the collector plenum (316).

[0042] One or more growth monitors (310) are located within the exhaust outlet openings (308a, 308b) or immediately downstream of the exhaust outlet openings (308a, 308b). A first growth monitor (310) is placed within the first exhaust outlet opening (308a) or immediately downstream of the exhaust outlet opening (308a). A second growth monitor (310) is placed within the second exhaust outlet opening (308b) or immediately downstream of the second exhaust outlet opening (308b). The growth monitors (310) being placed immediately downstream of the exhaust outlet openings (308a, 308b) is defined as the growth monitors (310) being placed within 10 mm of the exhaust outlet openings (308a, 308b) and away from the pin arrays (314).

[0043] The baffle plates (304) narrow the passage through which exhaust gases pass through the exhaust plenums (312a, 312b) and thus increase the density or concentration of exhaust gases flowing over the growth monitors (310). To ensure that the growth monitors (310) do not block the third flow path (322) but are instead positioned in alignment with the third flow path (322), the growth monitors (310) are positioned on either the uppermost surface (326) or the lowermost surface (327) (Fig. 3b) of the exhaust plenums (312a, 312b). The growth monitors (310) are positioned at least partially inside the collector plenum (316).

[0044] The exhaust gas passes over the growth monitors (310) and into the collector plenum (316) before being removed from the exhaust collector (206) through the conduit opening (306) of the exhaust conduit (323) (Fig. 3b).

[0045] A conduit opening (306) is positioned in the portion of the collector plenum (316) opposite the outlet openings (308a, 308b). The conduit opening (306) is configured to enable the discharge of exhaust gas from the exhaust collector (206) through the exhaust conduit (323) and to the exhaust pump (157). Adjacent to the conduit opening (306) and within the collector plenum (316) is another growth monitor (310). The growth monitor (310) adjacent to the conduit opening (306) is positioned on the rear side wall (321) (Fig. 3b) of the collector plenum (316), furthest from the outlet openings (308a, 308b). In some embodiments, the growth monitor (310) may be placed directly above the conduit opening (306) or within the conduit opening (306), for example, within the upper part of the exhaust conduit (323).

[0046] FIG. 3b illustrates a side cross-sectional view of an exhaust system (178) of a deposition chamber (100) of FIG. 1 according to embodiments 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), and accordingly, the exhaust plenums (312a, 312b) extend through the flow module (112). The fins (302) are positioned adjacent to the process volume (136).

[0047] The fins (302) and baffle plates (304) extend to the full height of the exhaust plenums (312a, 312b), and accordingly, the fins (302) and baffle plates (304) extend between the uppermost surface (326) and the lowermost surface (329) of the exhaust plenums (312a, 312b). Growth monitors within the fin arrays (314) are positioned on the uppermost surface (326).

[0048] The exhaust collector (206) is connected to the rear end of the exhaust system (178). The exhaust collector (206) includes a top surface (324), a bottom surface (327), and a rear sidewall (321). Growth monitors (310) immediately downstream of the exhaust outlet openings (308a, 308b) are positioned on the top surface (324) of the collector plenum (316) within the exhaust collector (206). Another growth monitor (310) is positioned on the rear sidewall (321) of the collector plenum (316). The positioning of the growth monitors (310) enables accurate film growth rate measurements by each of the growth monitors (310). Measurements from each of the growth monitors (310) can be mapped to identify differences in growth rates across different positions of the substrate (102).

[0049] The conduit opening (306) is positioned through the lowest 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 fluidically connected to the exhaust pump (157). Another growth monitor (310) may be positioned on the inner wall of the exhaust conduit (323) downstream of the growth monitor (310) on the rear side wall (321) of the collector plenum (316).

[0050] In some embodiments, more or fewer growth monitors (310) may be utilized within the exhaust system (178). In some embodiments, only the growth monitors (310) adjacent to the exhaust outlet openings (308a, 308b) are placed within the exhaust system (178). In other embodiments, the growth monitors (310) adjacent to the exhaust outlet openings (308a, 308b) may be a single growth monitor (310). In yet other embodiments, the growth monitors (310) adjacent to the exhaust outlet openings (308a, 308b) and the growth monitor (310) on the rear sidewall (321) of the collector plenum (316) are utilized.

[0051] FIG. 4a illustrates a growth monitor (310) for use in the deposition chamber (100) of FIG. 1 according to embodiments of the present disclosure. The growth monitor (310) comprises a sensor holder (402), a crystal (406) disposed within the sensor holder (402), a rear contact (408) in contact with a first surface (422) (e.g., rear) of the crystal (406), a protective coating (416) disposed on a second surface (424) (e.g., front) of the crystal (406), a front contact (410) in contact with the protective coating (416), a feed through (428) disposed through the sensor holder (402) for electrical contacts to the rear of the crystal, a gas inlet (427) fluidly communicating with the rear of the crystal, and a sensor opening (414) disposed through the sensor holder (402) and exposing the front surface (424) of the crystal to gases flowing through an exhaust system (178). In some embodiments, exposing the front surface (424) of the crystal includes exposing the protective coating (416). In some embodiments, a plenum (429) is formed between the sensor holder (402) and the rear contact (408) or the rear surface (422) of the crystal (406).

[0052] Growth monitors (310) are configured to be positioned within the deposition chamber (100) and thus to account for the reaction process chemistry within the exhaust system (178). The materials of the sensor holder (402), the rear contact (408), and the front contact (410), as well as the protective coating (416), affect the reactivity of the growth monitors (310) and the process chemistry within the deposition chamber (100). Accordingly, material compositions are selected that reduce the reactivity of the growth monitors (310) and the process chemistry within the deposition chamber (100) while still enabling accurate film thickness measurements on the growth monitors (310).

[0053] The sensor holder (402) serves as a case in which the rear contact (408), the front contact (410), and the crystal (406) are placed. The sensor holder (402) is formed of a number of parts, such as a first part (405) and a second part (404). The first part (405) has a cavity formed inside, and the rear contact (408) is located within the cavity. The crystal (406) is also located within the cavity and contacts the rear contact (408). A feed-through (428) is placed in the rear contact (408) through the first part (405). The feed-through (428) provides access to the rear surface (422) of the crystal for electrical connections, such as a temperature monitor. In some embodiments, the temperature monitor (431) is a thermocouple configured to monitor the temperature of the rear surface (422) of the crystal. In some embodiments, the temperature monitor is a probe attached to the rear of the crystal sensor head and coupled communically to a controller (e.g., described with reference to the controller (440) in FIG. 4b). Other temperature monitors are also considered. The rear gas inlet (427) is fluidly connected to the feed-through (428) and the plenum (429), so that gas can flow into the feed-through (428) and into the plenum (429). The gas exits the plenum through the gas outlet (434) to the exhaust without entering the process volume of the chamber. It has been found that directing the purge gas to the exhaust without entering the process volume enables rear purging without affecting process reactions within the process volume, such as chemical vapor deposition.

[0054] The second part (404) includes a sensor opening (414) positioned through itself and is positioned on the side of the first part (405) containing a cavity. A protective coating (416) is positioned on the second surface (424) of the crystal (406) and in direct contact with it. The protective coating (416) is positioned at least partially within the sensor opening (414), and accordingly, the protective coating (416) is exposed to exhaust gases (401) flowing through the exhaust system (178). The protective coating (416) and the crystal (406) are held at least partially in place by a gripping force between the first part (405) and the second part (404). One or more sealing rings (412) are positioned within the second part (404) and in contact with the exposed surface (426) of the protective coating (416). One or more sealing rings (412) are configured to provide a seal between the atmosphere within the exhaust system (178) and other components of the growth monitor (310) other than the protective coating (416). The front surface (424) of the crystal or the protective coating (416) is exposed to a front purge gas (403) between sensor samplings. The purge gas (403) is configured to clean the front surface (424) of the protective coating (416) or the crystal (406) between samplings.

[0055] The protective coating (416) is formed from either alumina (Al2O3) or silicon oxide, such as silicon dioxide (SiO2). The protective coating (416) is formed from a material that does not degrade when exposed to epitaxial deposition process conditions or process gases. The protective coating (416) may be a lens or a coating applied to a quartz crystal (406). The protective coating (416) has a thickness of less than about 10 µm, for example, about 1 nm to about 10 nm, for example, about 1 nm to about 5 nm. The small thickness enables protection of the quartz crystal (406) without significant damping of the vibration of the quartz crystal (406). It has been found that purging the front surface (424) of the crystal (406) protects the protective coating (416) from corrosive gases and, in some cases, makes it possible to thin the thickness of the protective coating (416) for the sensors without purging.

[0056] FIG. 4b illustrates a schematic diagram of a growth monitoring system (400) for use within the deposition chamber (100) of FIG. 1, according to embodiments of the present disclosure. The growth monitoring system (400) comprises a growth monitor (310), a front gas inlet valve (432) coupled to a gas source (430), a rear gas inlet valve (438) coupled to a gas source (430), and a heat exchanger (436) coupled to a rear gas inlet line (437). The heat exchanger (436) can heat and / or cool the rear gas in the rear gas inlet line (437). In some embodiments, the heat exchanger (436) is a chiller. The rear gas can be purged from the growth monitoring system through a gas outlet (434). In some embodiments, the front gas inlet valve (432) is a normally open pneumatic valve. The front gas inlet valve (432) is communicably coupled to the controller (440) so that the valve is closed when the growth monitor is measuring the characteristics of the deposition gas and the valve is opened when the monitor is not measuring the characteristics. In some embodiments, the rear inlet valve (438) is communicably coupled to the controller (440) and can control the rear gas flow to the rear (422) of the crystal. The rear inlet valve (438) is a mass control valve, a limiter, or a combination thereof. In some embodiments, the crystal is a quartz crystal microbalance (QCM). The QCM sensor measures the change in mass per unit area by measuring the frequency change of the quartz crystal resonator. The frequency change is influenced by the characteristics of the process conditions, such as temperature, pressure, and film growth rate. The QCM can measure frequency change data that can be converted to approximate the film deposition thickness and / or film growth rate. The sensor described herein is particularly suitable for monitoring the growth of films in chemical vapor deposition processes, such as epitaxy growth.

[0057] FIG. 5 illustrates a block flow diagram of a method (500) for monitoring film growth. The method (500) comprises the steps of flowing a process gas over a growth monitor containing a crystal (502), flowing a back gas over the back of the crystal (504), purging the front of the crystal using a front purge gas (506), and using the crystal to measure the characteristics of the process gas or the film deposited by the process gas (508). The step of flowing the process gas (502) exposes the front of the crystal or a protective coating. In some embodiments, the flow rate of the process gases is about 5 slm to about 50 slm, e.g., about 20 slm to about 40 slm. In some embodiments, the pressure of the process volume is about 1 torr to about 75 torr, e.g., about 25 torr to about 50 torr. In some embodiments, the temperature of the substrate is maintained from about 300 °C to about 1150 °C, e.g., from about 500 °C to about 800 °C. The process gas may be any gas suitable for use in epitaxial chemical vapor deposition processes.

[0058] The front of the crystal is purged during the front purging time and is determined based on a sampling window for measuring the characteristics of the process gas or the deposited film. In some embodiments, the characteristic is film thickness growth on a portion of the growth monitor. The characteristic may correspond to film growth on a substrate within a process chamber. In some embodiments, the method includes the step of calculating the film growth rate on the substrate during processing using the measured characteristic. Front purging prevents deposition on the front of the sensor when the sensor is not used to detect deposition.

[0059] Purge of the front surface of the crystal is periodically alternated with the measurement of characteristics. The sample window is determined based on one or more of the process deposition film thickness, process gas composition, process chamber preventive maintenance schedule, or combinations thereof. It has been found that purge of the front surface of the crystal (or protective coating) extends the lifespan of the crystal, so that the maintenance of the crystal can be synchronized with the preventive maintenance of the process chamber, such as about 1 to 6 months, e.g., 2 to 4 months. In some embodiments, the measurement of characteristics using the crystal has a total sampling time of about 10% to about 100%, e.g., about 15% to about 50% of the total process time for processing the substrate. It has been found that reducing the total sampling time relative to the total process time for processing the substrate can increase the lifespan of the crystal and extend the time between preventive maintenance, e.g., replacing the crystals. In some embodiments, the front surface of the crystal is purged for about 10 seconds to 1 hour, e.g., 20 seconds to 30 minutes. The sample window, for example, the timing, duration, and frequency of the front purge, is controlled using the process recipe entered for each process.

[0060] The method may further include the steps of measuring the temperature of the crystal, for example, at the back of the crystal, using a temperature monitor (431), and adjusting the temperature of the crystal by adjusting the gas flow rate and / or gas temperature of the back gas. The temperature of the crystal may be maintained at a crystal temperature of about 20 °C to about 190 °C, for example, about 50 °C to about 140 °C. Without being bound by theory, maintaining the sensor temperature within this temperature range is considered to enable repeatability of measurement accuracy. Additionally, since the main mechanism of mass deposition of the crystal phase is condensation, maintaining the sensor temperature low is considered to reduce condensation of the crystal phase. Reduced condensation of the crystal phase leads to higher deposition on the substrate and greater sensor read sensitivity. Condensation of the crystal phase is particularly affected by deposition gases used in epitaxial chemical vapor deposition, such as silanes (Si x H y ), halogen silanes, chloride-containing compounds, boron-containing compounds, or combinations thereof are observed. The crystal temperature range is determined based on the temperature and pressure at which condensation begins to form on the crystal phase, depending on the deposition gas composition. It has been found that front and / or rear purging enables improved temperature control compared to water cooling, e.g., through channels within the casing. Each of the front and rear purge gases can flow in substantially the same direction as the deposition gas. Flowing the purge gas in the same direction as the deposition gas is believed to enable the efficient removal of the deposition gas from the sensor components.

[0061] In some embodiments, flowing the back gas to the back of the crystal involves flowing the back gas at a first flow rate while measuring characteristics and flowing the back gas at a second flow rate when not measuring characteristics. In some embodiments, the first flow rate is higher than the second flow rate, and the back gas is at a reduced temperature relative to the crystal temperature of the crystal. In some embodiments, the second flow rate is substantially constant during processing and sampling and can be adjusted based on the temperature reading of the crystal. Without being bound by theory, it is assumed that the temperature of the crystal increases during sensor sampling. It has been found that increasing the gas flow rate across the back of the crystal reduces the temperature of the crystal during detection and reduces the temperature difference of the crystal between detection and non-detection. Depending on the temperature measurement provided by the temperature monitor (431), the gas flow rate of the purge gas to the back of the crystal can be adjusted and / or the amount of heat exchanged to the purge gas in the heat exchanger (436) can be adjusted. In some embodiments, the control method of the back purge gas is a control loop distinct and separate from the control method of the front purge gas.

[0062] In some embodiments, the back gas flows continuously while purging the front of the crystal and measuring its properties. The back gas and front purge gas are selected from helium, hydrogen (e.g., H2), nitrogen (e.g., N2), argon, and combinations thereof. The flow rate of the purge gas to the back and front, respectively, is about 0.5 slm to about 5 slm. Although the back gas and front purge gas are described as coming from the same gas source, providing gases from different gas sources is also considered.

[0063] FIG. 6 illustrates a control schematic (600) for use within the deposition chamber (100) of FIG. 1 according to embodiments of the present disclosure. A controller (120) is configured to receive data or input as sensor readings (602) from each of the growth monitors (310). The controller (120) has a system model (606) of the deposition chamber (100) or communicates with the system model (606). The system model (606) includes a heating model and a gas flow module. The system model (606) is a program configured to estimate gas flow and heating within the deposition chamber (100) throughout the deposition process. The controller (120) is further configured to store readings and calculations (604).

[0064] The readings and calculations (604) include previous sensor readings (602) as well as any other previous sensor readings within the deposition chamber (100). The readings and calculations (604) further include calculated values ​​stored since the sensor readings (602) were measured by the controller (120) and executed through the system model (606). Accordingly, the controller (120) is configured to retrieve both the stored readings and calculations (604) and to store the readings and calculations (604) for future use. Retaining the previous readings and calculations enables the controller (120) to adjust the system model (606) over time to reflect a more accurate version of the deposition chamber (100).

[0065] In the embodiments described herein, the controller (120) includes a programmable central processing unit (CPU) that operates with memory and mass storage devices, an input control unit, and a display unit (not shown). The controller (120) monitors the flow of precursors, process gases, and purge gases. Support circuits are coupled to the CPU to support the processor in a conventional manner. In some embodiments, the controller (120) includes a plurality of controllers (120), and accordingly, stored readings and calculations (604) and a system model (606) are stored in a controller separate from the controller (120) that operates the deposition chamber (100). In other embodiments, all system models (606) and stored readings and calculations (604) are stored in the controller (120).

[0066] The controller (120) is configured to control heating and gas flow through the deposition chamber (100) by providing outputs to the lamps and gas flow control units (608). The lamps and gas flow control units (608) include upper lamps (141), lower lamps (143), a process gas source (151), a purge gas source (162), and an exhaust pump (157). The controller (120) can also control the motion assembly (121) within the deposition chamber (100).

[0067] The controller (120) is configured to adjust the output for each of the ramps and gas flow controllers (608) based on sensor readings (602), a system model (606), and stored readings and calculations (604). The controller (120) includes embedded software and a compensation algorithm for calibrating the growth monitor (310) frequency shift for the film thickness on the substrate (102). The film thickness on the substrate (102) may be measured when the substrate (102) leaves the deposition chamber or between process operations to provide a reference for film thickness growth rates measured using the growth monitors (310). The controller (120) may include a machine learning algorithm and may use regression or clustering techniques. The algorithm is an unsupervised or supervised algorithm.

[0068] FIG. 7 illustrates a method (700) for adjusting process conditions within the deposition chamber (100) of FIG. 1 according to embodiments of the present disclosure. The method (600) utilizes the controller (120) described herein to improve film thickness uniformity and properties across the substrate (102) as well as growth monitors (310) within the deposition chamber (100).

[0069] During method (700), the first substrate is processed in a processing chamber during operation (702). The first substrate may be a substrate (102) and the processing chamber is a deposition chamber (100). Processing the first substrate during operation (702) 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 upper lamps (141) and lower lamps (143). Gas flows through the process volume (136) from process gas inlets (114) and purge gas inlets (164) before being removed through exhaust gas outlets (116).

[0070] While the first substrate is being processed within the processing chamber, growth monitors (310) are used to measure film thickness growth on the monitors during another operation (704). The measurement of film thickness growth on the growth monitors (310) is performed as a rolling operation. A controller, such as a controller (120), is configured to receive input from a combination of growth monitors (310) described in relation to FIGS. 3a and 3b. The input is used to estimate film growth on the first substrate. Once the first substrate being processed within the processing chamber is completed, the film thickness may be measured during another operation (706) using one or more other non-contact sensors in an adjacent chamber or within the processing chamber. Measuring film growth on the first substrate during operation (706) is performed in a non-destructive manner, for example, by using one or more non-contact sensors. The non-contact sensors may be laser thickness gauges and may take a number of distinct measurements across the surface of the first substrate or scan the length of the first substrate.

[0071] Since radiation from process gases and heating sources interferes with sensor readings and reduces reading sensitivity and precision, the non-contact sensors used during operation (706) do not necessarily need to be utilized for measuring film thickness during substrate processing. Accordingly, the growth monitors (310) enable the adjustment of process conditions, such as heating and gas flow, while the first substrate is being processed.

[0072] Measurements of film growth on the first substrate enable the growth rate on the first substrate to be calculated during another operation (708). Calculating the growth rate on the first substrate during operation (708) verifies the accuracy of the models used within the controller and enables the processing chamber model to be adjusted during another operation (710). Adjusting the processing chamber model during operation (710) enables better use of the growth monitors (310) for a specific process. Once the model is adjusted, processing of another substrate, e.g., the second substrate, is performed, and operations (702 to 710) are repeated. Operations (702) can be looped to continuously adjust the accuracy of the processing chamber model (710) and improve the film thickness growth results. When preventive maintenance is performed on the processing chamber, the processing chamber model can be reset or adjusted, and the method (700) is restarted. Thus, the film thickness is a result that is continuously improved between each substrate. Additionally, this enables precise film thickness as films accumulate on surfaces within the process volume and as the ramps age, and overcomes changes in processing chamber properties.

[0073] Each face of the crystal placed on the growth monitor can be controlled based on various different deposition processes using purge gases. Front purging can control the sample window for epitaxial film growth, and back continuous purging can be used to control the temperature of the crystal for different epitaxial processes with different precursors. Controlling the purging conditions for the sensor can extend the lifespan of the crystal and enable the replacement of crystals during preventive maintenance of the process chamber.

[0074] Although the foregoing relates to embodiments of the present disclosure, other and additional embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the following claims.

Claims

Claim 1 A film growth monitor comprising: a sensor holder; a crystal disposed in the sensor holder — said crystal includes a front surface and a back surface —; an opening formed in the sensor holder; a gas inlet disposed through the sensor holder to the back surface of the crystal and a plenum formed by the sensor holder; a gas outlet fluidly coupled to the plenum; and a protective coating disposed over the front surface of the crystal — said protective coating is formed of alumina or silicon oxide —. Claim 2 A membrane growth monitor according to claim 1, further comprising a front inlet valve capable of controlling front gas flow to the front of the determination. Claim 3 In paragraph 2, the above-mentioned front inlet valve is a normally open pneumatic valve, a membrane growth monitor. Claim 4 A film growth monitor according to claim 1, further comprising a rear inlet valve coupled to the gas inlet, wherein the rear inlet valve is capable of controlling rear gas flow to the rear of the crystal. Claim 5 In paragraph 4, the rear inlet valve is a membrane growth monitor, which is a mass control valve, a limiter, or a combination thereof. Claim 6 A film growth monitor according to claim 1, further comprising a thermocouple coupled to the rear surface of the above-mentioned crystal. Claim 7 A film growth monitor according to claim 1, further comprising a rear contact disposed on the rear surface of the above-mentioned determination. Claim 8 A membrane growth monitor according to claim 1, further comprising a heat exchanger coupled to the gas inlet. Claim 9 A film growth monitor according to any one of claims 1 to 8, wherein the sensor holder comprises a first portion including a cavity and a second portion positioned on the side of the first portion, the crystal is disposed within the cavity of the first portion and surrounded between the first portion and the second portion, the opening is formed in the second portion of the sensor holder, the gas inlet is disposed through the first portion of the sensor holder, the gas outlet is formed in the first portion of the sensor holder, the plenum is formed by a portion of the cavity between the back surface of the crystal and the first portion of the sensor holder, and the protective coating is disposed at least partially in the opening formed in the second portion. Claim 10 In claim 9, a membrane growth monitor further comprising an electrical connection extending through a first portion of the sensor holder and to the rear surface of the determination. Claim 11 A film growth monitor according to claim 10, further comprising: a front contact in contact with the protective coating and disposed between the protective coating and a second portion of the sensor holder; and one or more sealing rings in contact with the protective coating and disposed between the protective coating and a second portion of the sensor holder. Claim 12 A membrane growth monitor according to claim 11, further comprising: a front inlet valve capable of controlling front gas flow to the front of the crystal; a rear inlet valve fluidically connected to the gas inlet — the rear inlet valve is capable of controlling rear gas flow to the rear of the crystal —; a heat exchanger fluidly connected to the gas inlet through the rear inlet valve; and a controller communically coupled to the front inlet valve and the rear inlet valve. Claim 13 A method for measuring film characteristics for epitaxial chemical vapor deposition, comprising: a step of flowing a process gas over a film growth monitor according to claim 1; a step of flowing a back gas over a back surface of a crystal; a step of purging the front surface of the crystal using a front purge gas; and a step of measuring the characteristics of the process gas using the crystal, wherein the step of measuring the characteristics of the process gas occurs when the front surface of the crystal is not being purged. Claim 14 A method for measuring membrane characteristics according to claim 13, wherein the front purge time is determined based on the sampling frequency for measuring the characteristics of the process gas, and the step of purging the front of the determination is cyclically alternated with the step of measuring the characteristics. Claim 15 A method for measuring film characteristics according to claim 14, wherein the sampling frequency and sampling duration are determined based on one or more of the process deposition film thickness, process gas composition, process chamber preventive maintenance schedule, or combinations thereof. Claim 16 A method for measuring film characteristics according to claim 13, further comprising the steps of: measuring the temperature of the crystal; and adjusting the temperature of the crystal by adjusting the gas flow rate and / or gas temperature of the back gas. Claim 17 A method for measuring film properties according to claim 16, wherein the step of adjusting the temperature of the crystal includes maintaining a crystal temperature of 20 ℃ to 190 ℃. Claim 18 A method for measuring film characteristics according to claim 16, wherein the step of flowing the back gas to the back of the crystal comprises the step of flowing the back gas at a first flow rate while measuring the characteristic, and the step of flowing the back gas at a second flow rate when not measuring the characteristic, wherein the first flow rate is higher than the second flow rate, and the back gas is at a reduced temperature relative to the crystal temperature of the crystal. Claim 19 A method for measuring film characteristics, wherein the back gas is continuously flowed during the step of purging the front surface of the crystal and the step of measuring the characteristics in paragraph 13. Claim 20 A method for measuring membrane properties according to claim 13, wherein the back gas and the front purge gas are selected from helium, hydrogen, nitrogen, and combinations thereof. Claim 21 In paragraph 13, a method for measuring film characteristics, wherein the above characteristic is film thickness growth on a part of the growth monitor. Claim 22 A method for measuring film characteristics according to claim 21, further comprising the step of calculating the film growth rate on a substrate during processing using the measured characteristics. Claim 23 In claim 13, the step of measuring the above characteristics is a method for measuring film characteristics having a total sampling time of 10% to 50% of the total process time. Claim 24 An exhaust passage body for substrate processing, comprising: an exhaust plenum; an exhaust inlet opening formed through a first end of the exhaust passage body and fluidly connected to the exhaust plenum; an exhaust outlet opening formed through a second end of the exhaust passage body and fluidly connected to the exhaust plenum; and at least one growth monitor — the at least one growth monitor is disposed adjacent to the exhaust outlet opening and configured to measure the thickness of a material deposited on the at least one growth monitor — wherein the at least one growth monitor comprises: a sensor holder; a crystal disposed in the sensor holder — the crystal comprises a front surface and a rear surface —; an opening formed in the sensor holder; a gas inlet disposed through the sensor holder to the rear surface of the crystal and a sensor plenum formed by the sensor holder; a gas outlet fluidly coupled to the sensor plenum; and a protective coating disposed over the front surface of the crystal — the protective coating is formed of alumina or silicon oxide —; an exhaust passage body. Claim 25 In claim 24, the exhaust passage body further comprises a fin array including a plurality of fins, wherein at least one growth monitor is disposed within the fin array. Claim 26 In claim 25, the exhaust passage body further comprises one or more baffles that narrow the exhaust plenum, wherein the exhaust outlet opening is narrower than the exhaust inlet opening. Claim 27 In paragraph 26, the at least one growth monitor is an exhaust passage body located within the exhaust outlet opening or downstream of the exhaust outlet opening. Claim 28 An exhaust passage body according to any one of claims 24 to 27, wherein the sensor holder comprises: a first portion including a cavity; and a second portion positioned on the side of the first portion, the crystal is disposed within the cavity of the first portion and surrounded between the first portion and the second portion, the opening is formed in the second portion of the sensor holder, the gas outlet is formed in the first portion of the sensor holder, the gas inlet is disposed through the first portion of the sensor holder, the plenum is formed by a portion of the cavity between the rear surface of the crystal and the first portion of the sensor holder, and the protective coating is disposed at least partially in the opening formed in the second portion. Claim 29 A chamber comprising: a chamber body; a window — said chamber body and said window at least partially define a process volume —; a plurality of heat sources configured to heat said process volume; a substrate support disposed within said process volume; a liner lining at least partially lining said chamber body; a plurality of gas inlets; one or more exhaust gas outlets disposed on a side opposite to said process volume from said gas inlets; an exhaust system fluidly connected to said one or more exhaust gas outlets — said exhaust system comprises an exhaust passage body —; and one or more growth monitors disposed within said exhaust passage body, wherein the one or more growth monitors comprise a sensor holder, a crystal disposed in said sensor holder — said crystal comprises a front and a rear surface — an opening formed in said sensor holder, a gas inlet disposed through said sensor holder to a plenum adjacent to the rear surface of said crystal, a protective coating disposed over said front surface of said crystal — said protective coating is formed of alumina or silicon oxide — and a gas outlet fluidly coupled to said plenum. Claim 30 In claim 29, the exhaust passage body comprises a fin array including a plurality of fins, and the one or more growth monitors are disposed within the fin array, the chamber. Claim 31 In claim 29, the exhaust passage body further comprises one or more baffles that narrow one or more exhaust plenums adjacent to one or more exhaust outlet openings. Claim 32 In paragraph 31, the one or more growth monitors are located within or downstream of the one or more exhaust outlet openings, in a chamber. Claim 33 In claim 29, the sensor holder comprises: a first portion including a cavity; and a second portion positioned on the side of the first portion, wherein the crystal is disposed within the cavity of the first portion and surrounded between the first portion and the second portion, the opening is formed in the second portion of the sensor holder, the gas outlet is formed in the first portion of the sensor holder, the gas inlet is disposed through the first portion of the sensor holder, the plenum is formed by a portion of the cavity between the rear surface of the crystal and the first portion of the sensor holder, and the protective coating is disposed at least partially in the opening formed in the second portion, a chamber.

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