Heat soaking and ESC clamping sequence for highly curved substrates

Abstract

A method for processing a substrate includes: a) transferring the substrate to an electrostatic chuck (ESC) pedestal of a processing chamber; b) increasing a pressure in the processing chamber to a first predetermined pressure within a first predetermined pressure range; c) soaking the substrate at the first predetermined pressure for a first predetermined time without clamping the substrate; d) after the first predetermined time, ramping a clamping voltage supplied to the ESC to the first clamping voltage for a second predetermined time; e) after the second predetermined time, increasing the pressure in the processing chamber to a predetermined process pressure greater than the first predetermined pressure; and f) processing the substrate at the predetermined process pressure.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 288,547, filed December 11, 2021. The entire disclosure of the above application is incorporated herein by reference.

[0002] The present disclosure relates to substrate processing systems and, more particularly, to soak sequences and electrostatic chuck clamping methods for deposition processes. [Background technology]

[0003] The background discussion provided herein is intended to provide a general overview of the contents of the present disclosure. The work of the currently named inventors within the scope of what is described in this background section, as well as aspects of the description that may not otherwise be considered prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure.

[0004] Substrate processing systems are used to perform processes on substrates, such as semiconductor wafers. Examples of processes include deposition, etching, cleaning, and / or other processes. During processing, the substrate undergoes multiple deposition, etching, cleaning, and / or other processes in one or more processing chambers. After the substrate is processed in one processing chamber, it is typically moved to one or more additional processing chambers for subsequent processing steps.

[0005] The substrate is typically transferred onto an electrostatic chuck (ESC) pedestal in one of the processing chambers. There may be a temperature difference between the substrate and the pedestal. Before processing the substrate, the substrate is heat soaked and clamped. These steps are preferably performed quickly to increase throughput. If the substrate is heated too quickly by the ESC, it may be damaged. Uniform heating of the substrate is related to the temperature difference between the substrate and the pedestal, the pressure in the processing chamber, the curvature of the substrate, the thermal conductivity of the gas in the processing chamber, the degree of clamping of the substrate, and / or other factors.

[0006] Ideally, the substrate is clamped in a flat position and has a uniform temperature from center to edge before processing begins. However, the substrate may be curved (center to edge curvature) during transport and / or substrate curvature may occur during heating of the substrate. The curvature may make it difficult to clamp the substrate in a flat position and / or may cause temperature non-uniformity (NU) from center to edge. If the substrate remains curved after clamping, there may be a gap between the edge of the substrate and the pedestal of the ESC during processing. If the substrate is curved after clamping, arcing may occur between the substrate and the minimum contact areas (MCAs) of the pedestal, which may damage the pedestal and increase production costs and downtime. If the substrate has a NU of temperature from center to edge during processing, defects are more likely to occur.

[0007] During processing, a gas delivery system supplies a process gas mixture to the processing chamber. A plasma may be used to drive chemical reactions. After processing, the substrate is unclamped and the substrate is removed from the processing chamber. Summary of the Invention

[0008] A method for processing a substrate includes: a) transferring the substrate to an electrostatic chuck (ESC) pedestal of a processing chamber; b) increasing a pressure in the processing chamber to a first predetermined pressure within a first predetermined pressure range; c) soaking the substrate at the first predetermined pressure for a first predetermined time without clamping the substrate; d) after the first predetermined time, increasing a clamping voltage supplied to the ESC to the first clamping voltage for a second predetermined time; e) after the second predetermined time, increasing the pressure in the processing chamber to a predetermined process pressure greater than the first predetermined pressure; and f) processing the substrate at the predetermined process pressure.

[0009] In other features, the method includes, after e) and before f), reducing the clamp voltage to a second clamp voltage less than the first clamp voltage when the pressure exceeds a second predetermined pressure that is greater than the first predetermined pressure and less than the predetermined process pressure.

[0010] In other features, the pressure is maintained at the first predetermined pressure for a second predetermined time.The substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

[0011] A method for soaking and clamping a substrate includes: a) transferring the substrate to an electrostatic chuck (ESC) pedestal of a processing chamber; b) increasing a pressure in the processing chamber to a first predetermined pressure within a first predetermined pressure range for a first predetermined time, the first predetermined pressure being greater than a predetermined process pressure; c) clamping the substrate using a first clamping voltage for a second predetermined time; d) decreasing the pressure in the processing chamber to a second predetermined pressure within a second predetermined pressure range for a second predetermined time; e) increasing the first clamping voltage to a second clamping voltage and increasing the pressure in the processing chamber for a third predetermined time; and f) processing the substrate at the predetermined process pressure.

[0012] In other features, the method includes after e) and before f) reducing the second clamping voltage to a third clamping voltage lower than the second clamping voltage when the pressure exceeds the second predetermined pressure, the second predetermined pressure being greater than the first predetermined pressure and less than the predetermined process pressure. The substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

[0013] A method for soaking and clamping a substrate includes: a) transferring the substrate to an electrostatic chuck (ESC) pedestal of a processing chamber; b) increasing the pressure in the processing chamber to a first predetermined pressure within a first predetermined pressure range for a first predetermined time; c) clamping the substrate at a first clamping voltage for a second predetermined time after the first predetermined time; d) unclamping the substrate for a third predetermined time after the second predetermined time; e) clamping the substrate at the second clamping voltage for a fourth predetermined time after the third predetermined time; f) increasing the pressure in the processing chamber to a predetermined process pressure after the fourth predetermined time; and g) processing the substrate at the predetermined process pressure.

[0014] In other features, the method includes, after e) and before f), when the pressure exceeds the second predetermined pressure, reducing the second clamp voltage to a third clamp voltage lower than the second clamp voltage, the second predetermined pressure being greater than the first predetermined pressure and less than the predetermined process pressure.

[0015] In other features, the pressure for the second predetermined time is the first predetermined pressure. The pressure for the third predetermined time is the first predetermined pressure. The first predetermined pressure is less than the arc pressure.

[0016] A substrate processing system for processing a substrate includes a process chamber with an electrostatic chuck having an electrode. A gas delivery system is configured to deliver a gas mixture to the process chamber. A voltage source is configured to supply a clamping voltage to the electrode. A controller is configured to cause the gas delivery system and the voltage source to a) increase the pressure in the process chamber in one or more steps to a first predetermined pressure within a first predetermined pressure range, b) soak the substrate at the first predetermined pressure for a first predetermined time without clamping the substrate, c) increase the clamping voltage supplied to the electrostatic chuck to the first clamping voltage for a second predetermined time after the first predetermined time, d) increase the pressure in the process chamber to a predetermined process pressure higher than the first predetermined pressure after the second predetermined time, and e) process the substrate at the predetermined process pressure.

[0017] In other features, after e) and before f), the controller is further configured to reduce the clamping voltage to a second clamping voltage less than the first clamping voltage when the pressure exceeds a second predetermined pressure greater than the first predetermined pressure and less than the predetermined process pressure. The pressure is maintained at the first predetermined pressure for the second predetermined time. The substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

[0018] A substrate processing system for processing a substrate includes a process chamber including an electrostatic chuck having an electrode. A gas delivery system is configured to deliver a gas mixture to the process chamber. A voltage source is configured to provide a clamping voltage to the electrode. A controller is configured to cause the gas delivery system and the voltage source to: a) increase the pressure in the process chamber in one or more steps for a first predetermined time to a first predetermined pressure within a first predetermined pressure range, the first predetermined pressure being greater than a predetermined process pressure; b) clamp the substrate using the first clamping voltage for a second predetermined time; c) decrease the pressure in the process chamber to a second predetermined pressure within a second predetermined pressure range for a second predetermined time; d) increase the first clamping voltage to the second clamping voltage and increase the pressure in the process chamber for a third predetermined time; and e) process the substrate at the predetermined process pressure.

[0019] In other features, after e) and before f), the controller is further configured to reduce the second clamping voltage to a third clamping voltage lower than the second clamping voltage when the pressure exceeds the second predetermined pressure, the second predetermined pressure being greater than the first predetermined pressure and less than the predetermined process pressure. The substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

[0020] A substrate processing system for processing a substrate comprises a process chamber including an electrostatic chuck having an electrode. A gas delivery system is configured to deliver a gas mixture to the process chamber. A voltage source is configured to provide a clamping voltage to the electrode. A controller is configured to cause the gas delivery system and the voltage source to: a) raise the pressure in the process chamber in one or more steps to a first predetermined pressure within a first predetermined pressure range during a first predetermined time; b) clamp the substrate with the first clamping voltage during a second predetermined time after the first predetermined time; c) unclamp the substrate during a third predetermined time after the second predetermined time; d) clamp the substrate with the second clamping voltage for a fourth predetermined time after the third predetermined time; e) raise the pressure in the process chamber to a predetermined process pressure after the fourth predetermined time; and f) process the substrate at the predetermined process pressure.

[0021] In other features, after e) and before f), the controller is further configured to reduce the clamping voltage to a second clamping voltage less than the first clamping voltage when the pressure exceeds a second predetermined pressure greater than the first predetermined pressure and less than the predetermined process pressure. The controller is configured to maintain the pressure at the first predetermined pressure for the second predetermined time. The substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

[0022] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0023] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, in which:

[0024] [Figure 1]FIG. 1 is a functional block diagram of an example substrate processing chamber according to the present disclosure.

[0025] [Diagram 2] FIG. 2 is a graph showing the height of curvature as a function of temperature during heating and cooling.

[0026] [Diagram 3] FIG. 3 is a graph showing the magnitude of curvature as a function of radius at different substrate temperatures.

[0027] [Figure 4] FIG. 4 is a flow chart of an example method for isolating and clamping a substrate according to the present disclosure.

[0028] [Diagram 5] FIG. 5 is a graph illustrating an example of the timing of changes in chamber pressure and clamping voltage according to the present disclosure.

[0029] [Figure 6A] FIG. 6A is a graph showing temperature as a function of ambient soak pressure.

[0030] [Figure 6B] FIG. 6B is a graph showing the thermal conductivity of helium as a function of ambient isothermal pressure.

[0031] [Figure 7] FIG. 7 is a flow chart of an example of another method for isolating and clamping a substrate according to the present disclosure.

[0032] [Figure 8] FIG. 8 is a graph illustrating an example of the timing of changes in chamber pressure and clamping voltage according to the present disclosure.

[0033] [Figure 9] FIG. 9 is a flow chart of an example of another method for isolating and clamping a substrate according to the present disclosure.

[0034] [Figure 10] FIG. 10 is a graph showing an example of timing of changes in chamber pressure and clamp voltage according to the present disclosure.

[0035] In the drawings, reference numbers may be reused to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] A curved substrate with high tensile strength experiences significant thermal deformation in high temperature processes during 3D-NAND fabrication. As used herein, a curved substrate with high tensile strength has a curvature of more than 200 micrometers (μm) at the edge at ambient or room temperature. Thermal deformation becomes a major issue when clamping the substrate. During the soaking and clamping sequence, the curved substrate with high tensile strength is transferred onto the pedestal of an electrostatic chuck (ESC).

[0037] Typically, the process is optimized to have the shortest cycle time. Generally, the higher the pressure, the more heating. Thus, the pressure is raised to a first predetermined pressure that is slightly lower than the arc pressure, which corresponds to the pressure at which arcing may occur if clamping is performed at the maximum clamping voltage. In some processes, the arc pressure is about 4-5 Torr. Once the pressure reaches the first predetermined pressure, the substrate is soaked for a period of time to reduce the NU of the temperature, after which the substrate is fully clamped. For example, when clamping is performed, the first predetermined pressure is close to the arc pressure (e.g., more than 75% of the arc pressure). At this point, the substrate has undesirable temperature non-uniformity (NU), since it tends to be hot in the center and cool at the edges.

[0038] After clamping the substrate, the chamber pressure is increased to a predetermined process pressure (greater than the first predetermined pressure) (or the process pressure) and the substrate is processed. In some examples, the predetermined process pressure is greater than about two times (+ / - 10%) the arc pressure, although other pressures may be used.

[0039] The above heat soaking and clamping sequence has limited clamping capability for curved substrates with high tensile strength. Before increasing the clamping voltage and pressure, the edge of the substrate may not be fully clamped on the pedestal surface. For example, the edge of the substrate may be misaligned with a gap of 0.1-4 mm. This gap increases the risk of arcing during the process. Arcing causes localized DC discharges that degrade the minimum contact area (MCA) surface of the ESC pedestal, thereby reducing the pedestal life and increasing costs. In addition, the backside of the substrate may be scratched during the process.

[0040] The present disclosure relates to systems and methods for performing a substrate soaking and clamping sequence using an electrostatic chuck (ESC). The systems and methods, described further below, address the issue of clamping substrates, such as high tensile strength, curved substrates, that are difficult to handle with conventional soaking and clamping techniques. These systems and methods demonstrate improved clamping and unclamping performance, reduced damage to the minimum contact area (MCA) surface of the ESC pedestal, and reduced scratches on the backside of the substrate, compared to conventional approaches.

[0041] In the first method, the substrate (such as a curved substrate with high tensile strength) is clamped with a small pressure during heating of the substrate, during which the deformation of the substrate is still small. To minimize the heating and processing time, clamping is usually performed with a larger pressure close to the arc pressure. However, this approach causes the substrate to bend even more, which causes problems during clamping.

[0042] After the substrate is transferred to the pedestal, the substrate is soaked at a first predetermined pressure for a first predetermined time during which the substrate has a low temperature and small deformation. In some examples, the first predetermined pressure is greater than 20% and less than 50% of the arc pressure. After the first predetermined time, the ESC clamps the substrate. After clamping the substrate, the pressure in the process chamber is increased to a second predetermined pressure for a second predetermined time. During the second predetermined time, the substrate reaches a thermal steady state with the ESC. After the second predetermined time, the pressure in the process chamber is adjusted to a process pressure and the process is started. In some examples, the process pressure is 9-12 Torr, although other pressures can be used.

[0043] In another approach, the substrate is transferred onto the pedestal of the ESC. The pressure in the process chamber is adjusted to a first predetermined pressure at or within a predetermined pressure range above the process pressure, and the substrate is allowed to soak in an inert gas environment. The thermal conductivity of the gas is proportional to the pressure of the gas. The higher the pressure, the more effective the heat transfer. Once the substrate reaches a thermal steady state (e.g., close to the desired substrate temperature), the pressure in the process chamber is reduced to a second predetermined pressure within a second predetermined pressure range (in some examples, below the arc pressure), and the ESC clamps the substrate with a first predetermined clamping voltage. After the substrate is chucked, the pressure in the process chamber is increased to the process pressure, and the clamping voltage is reduced to a second predetermined clamping voltage that is lower than the first predetermined clamping voltage.

[0044] In another approach, the substrate is transferred to the pedestal, the pressure in the processing chamber is set to a predetermined pressure range (less than the process pressure and the arc pressure), and the ESC clamps the substrate and uniformly heats the substrate for a first predetermined time. This allows the substrate to reach a thermal steady state quickly with small temperature non-uniformity from the center of the substrate to the edge of the substrate. The substrate is then allowed to rest by removing the ESC clamping force for a second predetermined time. This step removes lateral distortion due to thermal expansion. After the second predetermined time, the ESC clamps the substrate with small vertical distortion. The pressure in the processing chamber is then set to the process pressure and the process begins.

[0045] 1, an example of a substrate processing system 100 for performing substrate processing is shown. In the example described below, the substrate processing system may perform plasma enhanced chemical vapor deposition (PECVD). However, other types of substrate processing may be performed, with or without a plasma.

[0046] The substrate processing system 100 includes a process chamber 102, which surrounds the other components of the substrate processing system 100 and contains an RF plasma (if used). The substrate processing system 100 includes an upper electrode 104 and an electrostatic chuck (ESC) 106. In some examples, the ESC 106 includes a ceramic upper layer 161 bonded to a base plate 107, which functions as a lower electrode. During operation, a substrate 108 is disposed on the ESC 106 between the upper electrode 104 and the lower electrode. The ESC 106 includes an electrode 163 that electrostatically attracts the substrate during deposition. The electrode 163 can be a monopolar or bipolar electrode.

[0047] For example, the upper electrode 104 may include a showerhead 109 for introducing and distributing process gases. The showerhead 109 may include a stem portion connected at one end to the top surface of the processing chamber. A base portion is generally cylindrical and extends radially outward from the opposite end of the stem portion at a location away from the top surface of the processing chamber. The substrate-facing surface or faceplate of the showerhead base portion includes a number of holes through which process or purge gases flow. Alternatively, the upper electrode 104 may include a conductive plate, and process gases may be introduced in another manner.

[0048] An RF generation system 110 generates and outputs RF power to one of the upper electrode 104 and the lower electrode. The other of the upper electrode 104 and the lower electrode can be DC grounded, AC grounded, or floating. For example, the RF generation system 110 can include an RF generator 111 that generates RF power that is supplied by a matching and distribution network 112 to the lower electrode, and the upper electrode 104 is grounded (or vice versa). A lift pin assembly 122 including an actuator 120 and P lift pins (P is an integer greater than 2) is used to move the substrate in and out of the chamber.

[0049] The gas delivery system 130 includes one or more gas sources 132-1, 132-2, ..., and 132-N (collectively, gas sources 132), where N is an integer greater than zero. The gas sources 132 provide one or more process gases, such as, for example, a deposition precursor, a purge gas, an etching gas, etc. In some examples, vaporized precursors may be used (not shown). The gas sources 132 are connected to a manifold 140 by valves 134-1, 134-2, ..., and 134-N (collectively, valves 134), mass flow controllers 136-1, 136-2, ..., and 136-N (collectively, mass flow controllers 136), and valves 138-1, 138-2, ..., and 138-N (collectively, valves 138). The output of the manifold 140 is provided by the gas delivery system 130 to the process chamber 102. For example, the output of the manifold 140 is provided to a showerhead 109.

[0050] The heater 142 may be connected to a resistive heater disposed within the ESC 106. The heater 142 may be used to control the temperature of the ESC 106 and the substrate 108. Additionally, the ESC 106 may include internal channels (not shown) for flowing fluid from a fluid source (not shown) to further control the pedestal and substrate temperature. Valves 150 and pumps 152 may be used to evacuate reactants from the processing chamber 102 and / or control the pressure within the processing chamber. A controller 160 may be used to control various components of the substrate processing system 100 described herein.

[0051] As described further below, the controller 160 causes the robot arm 174 to load the substrate 108 onto the ESC 106. The controller 160 also causes the voltage source 172 to selectively apply one or more voltage signals to the electrodes 163 (monopolar or bipolar). The controller 160 communicates with the gas delivery system 130 to control the supply of process, purge, and / or inert gases. The controller communicates with the valves 150 and pumps 152 to control the pressure in the processing chamber and / or the evacuation of reactants.

[0052] 2 and 3, the curvature of the substrate during heating and cooling is affected in part by the substrate temperature and / or the chamber pressure. In Fig. 2, the height of the curvature during heating and cooling is shown as a function of temperature. In Fig. 3, the magnitude of the curvature is shown as a function of the radius of the substrate at different substrate temperatures.

[0053] 4 and 5, a method 400 for soaking and clamping a substrate is shown. After the substrate is transferred to the pedestal at 410, the chamber pressure is increased to a first predetermined pressure within a first predetermined pressure range at 414. In some examples, the first predetermined pressure range is 1-3 Torr, although other pressures can be used. At 418, the substrate is soaked at the first predetermined pressure for a first predetermined time t1. At this point, the substrate is at a relatively low temperature and pressure and deformation or curvature of the substrate is relatively small.

[0054] After a first predetermined time t1, the ESC clamp voltage is raised or ramped to clamp the substrate with increasingly greater force. In some examples, at 422, the ESC clamp voltage is ramped to the first clamp voltage over a second predetermined time t2.

[0055] Once the ESC reaches the first clamp voltage, the chamber pressure is increased or ramped towards the predetermined process pressure for a third predetermined time t3 at 426. In some examples, the pressure is increased to increase the substrate temperature.

[0056] When the pressure in the processing chamber reaches a second predetermined pressure (less than the predetermined process pressure), the ESC clamp voltage is optionally reduced to a second clamp voltage less than the first clamp voltage at 430. In some examples, the second clamp voltage is about 65%-85% of the first clamp voltage.

[0057] The pressure continues to increase to the process pressure for a fourth predetermined time t4. Between times t1 and t4, the substrate reaches a thermal steady state with the pedestal. After the fourth predetermined time t4, at 434, the substrate is processed in the processing chamber.

[0058] 6A and 6B, increasing the pressure increases both the thermal conductivity and temperature of the substrate. In FIG. 6A, the substrate temperature is shown as a function of the ambient isothermal pressure for a pedestal at 650° C. In FIG. 6B, the thermal conductivity of helium (He) is shown as a function of the ambient isothermal pressure. As can be seen, the higher the pressure, the higher the thermal conductivity of the gas. With a higher isothermal pressure, the substrate reaches a stable temperature closer to the pedestal set point.

[0059] 7 and 8, another method 700 for soaking and clamping a substrate is shown. The method 700 uses a higher pressure without clamping the substrate (to prevent arcing) during the initial soak time. After soaking at high pressure, the method reduces the chamber pressure to below the arc pressure and lightly clamps the substrate. The method increases the clamping voltage to a high clamping voltage and increases the pressure towards the process pressure. Before reaching the process pressure, the clamping voltage is reduced to the process clamping voltage.

[0060] More specifically, at 710, the substrate is transferred onto the pedestal of the ESC at ambient pressure (e.g., near vacuum). At 714, the chamber pressure is adjusted to a first predetermined pressure within a predetermined pressure range for a first predetermined time t1. In some examples, the first predetermined pressure is greater than the process pressure. During the first predetermined time t1, the substrate can be soaked in an inert gas environment, such as He, although other gases can be used.

[0061] As can be seen from FIG. 6A and FIG. 6B, the thermal conductivity of the gas is proportional to the pressure of the gas. The higher the pressure, the more effective the heat transfer. Once the substrate is sufficiently heated (e.g., the temperatures of the pedestal and the substrate are close enough), the substrate is lightly clamped, and then the pressure in the process chamber is reduced below the arc pressure to allow the substrate to be fully clamped with a higher clamping voltage (and without arcing). At 718, the ESC clamps the substrate using the first clamping voltage for a second predetermined time t2. In some examples, the first clamping voltage is less than the second clamping voltage or half of the maximum clamping voltage, and less than the third clamping voltage or the process clamping voltage. In some examples, the first clamping voltage is within a range of 20 to 50% of the second clamping voltage, and the third clamping voltage is within a range of 65 to 85% of the second clamping voltage, although other values ​​can be used.

[0062] After light clamping with the first clamping voltage, the pressure in the process chamber is reduced to a second predetermined pressure within a second predetermined pressure range at 722. In some examples, the second predetermined pressure range is below the arcing pressure, although other pressures may be used. In some examples, the second predetermined pressure is less than the pressure that would cause arcing when the second clamping voltage or the maximum clamping voltage is used.

[0063] After lowering the chamber pressure to the second predetermined pressure in 722, the clamp voltage is raised to the second clamp voltage for a second predetermined time t3 in 726. The pressure is raised towards the process pressure (less than the first predetermined pressure) in 730. When the chamber pressure reaches a third pressure (less than the process pressure, e.g., 60-80% of the process pressure), the clamp voltage is lowered to the third clamp voltage in 734. The pressure is raised to the process pressure in 738. The substrate is processed in 742.

[0064] 9, another method 900 for soaking and clamping a substrate is shown. The method 900 uses a two-stage clamping approach to soak and clamp the substrate. The chamber pressure is raised to a pressure less than the arc pressure and less than the process pressure. The substrate is then fully clamped at a first clamping voltage. During the soak time, the temperature of the substrate is raised to a low center-to-edge non-uniformity (NU) and the clamping voltage is removed to remove substrate distortion. The substrate is then clamped at a process clamping voltage less than the first clamping voltage. The pressure is then raised to the process pressure and the substrate is processed.

[0065] More specifically, at 910, the substrate is transferred to the pedestal. At 914, the pressure in the process chamber is raised to a first predetermined pressure within a first predetermined pressure range for a first predetermined time t1. In some examples, the first predetermined pressure range is less than the arc pressure, although other pressure ranges can be used. The substrate is soaked at the first predetermined pressure for a portion of the first predetermined time (e.g., t1').

[0066] At 918, after t1, the ESC fully clamps the substrate at a first predetermined pressure using a first clamping voltage for a second predetermined time t2 to uniformly heat the substrate, which allows the substrate to reach a thermal steady state quickly with low temperature non-uniformity (NU) from the center to the edge of the substrate.

[0067] Then, after a second predefined time t2 soak, the ESC clamping force is reduced or removed entirely at 926 for a third predefined time t3 to allow the substrate to rest. This step removes lateral distortion due to thermal expansion. After the third predefined time t3, the ESC re-clamps the substrate at 930 using a second clamping voltage. In some examples, the second clamping voltage is less than the first clamping voltage, although other clamping voltages can be used. In some examples, the second clamping voltage is within 50% to 85% of the first clamping voltage, although other clamping voltages can be used.

[0068] As a result of the two-stage clamping and soaking approach, the substrate is clamped with low vertical distortion. In some examples, the second clamping voltage is less than the first clamping voltage. After soaking for a fourth predetermined time t4, the pressure in the processing chamber is increased to a process pressure at 934, and the substrate is processed at 938. In some examples, the process pressure is greater than the first predetermined pressure.

[0069] The soaking and clamping sequences described herein have improved clamping and unclamping margins when processing high tensile strength, curved substrates, as compared to conventional soaking and clamping sequences. Additionally, the soaking and clamping sequences described in Figures 6A-10 reduce scratches on the backside of the substrate. The soaking and clamping sequences described herein have improved backside longest scratch metrics as the substrate is closer to a stable temperature when the final clamping occurs, as compared to conventional soaking and clamping sequences. In other words, there is less thermal expansion during the final clamping.

[0070] The above description is merely exemplary in nature and is not intended to limit the disclosure, its applications, or uses. The broad teachings of the disclosure can be implemented in various forms. Thus, while the disclosure includes specific examples, the true scope of the disclosure should not be so limited, since other modifications will become apparent upon review of the drawings, specification, and appended claims. It should be understood that one or more steps in a method may be performed in different orders (or simultaneously) without altering the principles of the disclosure. Furthermore, although each embodiment is described above as having specific features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and / or combined with the features of any other embodiment, even if the combination is not specified. In other words, the described embodiments are not mutually exclusive, and substituting one or more embodiments for one another still falls within the scope of the disclosure.

[0071] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using a variety of terms, including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed." When a relationship between a first element and a second element is described in the above disclosure, unless specified as "direct," the relationship may be a direct relationship where there are no other intervening elements between the first element and the second element, but may also be an indirect relationship where there are one or more intervening elements (spatial or functional) between the first element and the second element. As used herein, the phrase at least one of A, B, and C should be interpreted as meaning logical (A OR B OR C) using a non-exclusive logical OR, and not as meaning "at least one of A, at least one of B, and at least one of C."

[0072] In some implementations, the controller is part of a system, which may be part of the examples described above. Such systems may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling the operation of the system before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as a "controller" and may control various components or subparts of one or more systems. The controller may be programmed to control any of the processes disclosed herein, including delivery of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow settings, fluid delivery settings, position and motion settings, wafer transfer in and out of the tool, and wafer transfer in and out of other transfer tools and / or load locks connected or coupled to a particular system, depending on the processing requirements and / or type of system.

[0073] Broadly, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, and the like. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute the program instructions (e.g., software). The program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. In some embodiments, the operational parameters may be part of a recipe defined by a process engineer to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0074] In some embodiments, the controller may be part of or coupled to a computer that is integrated with, coupled to, or otherwise networked to the system, or a combination thereof. For example, the controller may be in the "cloud" and may be all or part of a fab host computer system, thereby enabling remote access of wafer processing. The computer may enable remote access to the system to monitor the current progress of a fabrication operation, examine the history of past fabrication operations, examine trends or performance indicators from multiple fabrication operations, modify parameters of a current process, set processing steps following a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that allows for entry or programming of parameters and / or settings. These parameters and / or settings are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify parameters for each processing step that is performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool that the controller is configured to couple to or control. Thus, as described above, the controller may be distributed, such as by having one or more separate controllers that are networked together and operate toward a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes is one or more integrated circuits on the chamber that communicate with one or more integrated circuits located remotely (e.g., at the platform level or as part of a remote computer) that combine to control the process in the chamber.

[0075] Without being limited thereto, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0076] As described above, depending on the process steps being performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used for material transport to and from containers of wafers to and from tool locations and / or load ports within a semiconductor manufacturing factory.

Claims

1. 1. A method for processing a substrate, comprising: a) transferring a substrate to an electrostatic chuck (ESC) pedestal of a processing chamber; b) increasing the pressure in the processing chamber to a first predetermined pressure within a first predetermined pressure range; c) soaking the substrate at the first predetermined pressure for a first predetermined time without clamping the substrate; d) after the first predetermined time, ramping a clamp voltage supplied to the ESC to a first clamp voltage for a second predetermined time; e) after the second predetermined time, increasing the pressure in the processing chamber to a predetermined process pressure greater than the first predetermined pressure; f) processing the substrate at the predetermined process pressure; A method comprising:

2. 2. The method of claim 1 , after e) and before f), when the pressure exceeds a second predetermined pressure that is greater than the first predetermined pressure and less than the predetermined process pressure, reducing the clamp voltage to a second clamp voltage that is less than the first clamp voltage.

3. 2. The method of claim 1 , The method of claim 1, wherein the pressure is maintained at the first predetermined pressure for the second predetermined time.

4. 2. The method of claim 1 , The method, wherein the substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

5. 1. A method for heat isolating and clamping a substrate, comprising: a) transferring a substrate to an electrostatic chuck (ESC) pedestal of a processing chamber; b) increasing the pressure in the processing chamber to a first predetermined pressure within a first predetermined pressure range for a first predetermined time, the first predetermined pressure being greater than a predetermined process pressure; c) clamping the substrate using a first clamping voltage for a second predetermined time; d) reducing the pressure in the processing chamber to a second predetermined pressure within a second predetermined pressure range during the second predetermined time; e) increasing the first clamp voltage to a second clamp voltage and increasing the pressure in the processing chamber for a third predetermined time; f) processing the substrate at the predetermined process pressure; A method comprising:

6. 6. The method of claim 5, after e) and before f), when the pressure exceeds a second predetermined pressure, reducing the second clamp voltage to a third clamp voltage lower than the second clamp voltage, the second predetermined pressure being greater than the first predetermined pressure and less than the predetermined process pressure.

7. 6. The method of claim 5, The method, wherein the substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

8. 1. A method for heat isolating and clamping a substrate, comprising: a) transferring a substrate to an electrostatic chuck (ESC) pedestal of a processing chamber; b) increasing the pressure in the processing chamber to a first predetermined pressure within a first predetermined pressure range for a first predetermined time; c) clamping the substrate at a first clamping voltage for a second predetermined time after the first predetermined time; d) unclamping the substrate for a third predetermined time period after the second predetermined time period; e) clamping the substrate at a second clamping voltage for a fourth predetermined time after the third predetermined time; f) after the fourth predetermined time, increasing the pressure in the processing chamber to a predetermined process pressure; g) processing the substrate at the predetermined process pressure; A method comprising:

9. 9. The method of claim 8, after e) and before f), when the pressure exceeds a second predetermined pressure, reducing the second clamp voltage to a third clamp voltage lower than the second clamp voltage, the second predetermined pressure being greater than the first predetermined pressure and less than the predetermined process pressure.

10. 9. The method of claim 8, The method of claim 1, wherein the pressure during the second predetermined time is the first predetermined pressure.

11. 9. The method of claim 8, The method of claim 1, wherein the pressure during the third predetermined time is the first predetermined pressure.

12. 9. The method of claim 8, The method, wherein the first predetermined pressure is less than an arc pressure.

13. 1. A substrate processing system for processing a substrate, comprising: a processing chamber including an electrostatic chuck having an electrode; a gas delivery system configured to deliver a gas mixture to the processing chamber; a voltage source configured to supply a clamping voltage to the electrode; a controller connected to the gas delivery system and to the voltage source; a) increasing the pressure in the processing chamber in one or more steps to a first predetermined pressure within a first predetermined pressure range; b) soaking the substrate at the first predetermined pressure for a first predetermined time without clamping the substrate; c) after the first predetermined time period, causing a clamping voltage supplied to the electrostatic chuck to be ramped up to a first clamping voltage for a second predetermined time period; d) after the second predetermined time, increasing the pressure in the processing chamber to a predetermined process pressure that is greater than the first predetermined pressure; e) processing the substrate at the predetermined process pressure. With a controller configured like this: A substrate processing system comprising:

14. 14. The substrate processing system of claim 13, after e) and before f), the controller is further configured to reduce the clamping voltage to a second clamping voltage lower than the first clamping voltage when the pressure exceeds a second predetermined pressure that is greater than the first predetermined pressure and less than the predetermined process pressure.

15. 14. The substrate processing system of claim 13, The substrate processing system wherein the pressure is maintained at the first predetermined pressure for the second predetermined time.

16. 14. The substrate processing system of claim 13, A substrate processing system, wherein the substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

17. 1. A substrate processing system for processing a substrate, comprising: a processing chamber including an electrostatic chuck having an electrode; a gas delivery system configured to deliver a gas mixture to the processing chamber; a voltage source configured to supply a clamping voltage to the electrode; a controller connected to the gas delivery system and to the voltage source; a) increasing the pressure in the processing chamber in one or more steps for a first predetermined time to a first predetermined pressure within a first predetermined pressure range, the first predetermined pressure being greater than a predetermined process pressure; b) clamping the substrate using a first clamping voltage for a second predetermined time; c) reducing the pressure in the processing chamber to a second predetermined pressure within a second predetermined pressure range during the second predetermined time; d) increasing the first clamp voltage to a second clamp voltage and increasing the pressure in the processing chamber for a third predetermined time; e) processing the substrate at the predetermined process pressure. With a controller configured like this: A substrate processing system comprising:

18. 20. The substrate processing system of claim 17, after e) and before f), the controller is further configured to reduce the second clamping voltage to a third clamping voltage lower than the second clamping voltage when the pressure exceeds a second predetermined pressure, the second predetermined pressure being greater than the first predetermined pressure and less than the predetermined process pressure.

19. 20. The substrate processing system of claim 17, A substrate processing system, wherein the substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

20. 1. A substrate processing system for processing a substrate, comprising: a processing chamber including an electrostatic chuck having an electrode; a gas delivery system configured to deliver a gas mixture to the processing chamber; a voltage source configured to supply a clamping voltage to the electrode; a controller connected to the gas delivery system and to the voltage source; a) increasing the pressure in the processing chamber in one or more steps for a first predetermined time to a first predetermined pressure within a first predetermined pressure range; b) clamping the substrate at a first clamping voltage for a second predetermined time after the first predetermined time; c) unclamping the substrate for a third predetermined time period after the second predetermined time period; d) clamping the substrate at a second clamping voltage for a fourth predetermined time period after the third predetermined time period; e) after the fourth predetermined time period, increasing the pressure in the processing chamber to a predetermined process pressure; f) processing the substrate at the predetermined process pressure. With a controller configured like this: A substrate processing system comprising:

21. 21. The substrate processing system of claim 20, after e) and before f), the controller is further configured to reduce the clamping voltage to a second clamping voltage lower than the first clamping voltage when the pressure exceeds a second predetermined pressure that is greater than the first predetermined pressure and less than the predetermined process pressure.

22. 21. The substrate processing system of claim 20, The substrate processing system, wherein the controller is configured to maintain the pressure at the first predetermined pressure for the second predetermined period of time.

23. 21. The substrate processing system of claim 20, A substrate processing system, wherein the substrate comprises a curved substrate having a curvature of greater than 200 μm at ambient temperature in an unclamped state.

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