Method and apparatus for semi-dynamic bottom-up reflow

Abstract

A method of filling a structure on a substrate uses a semi-dynamic reflow process. The method can include depositing a metal material on the substrate at a first temperature, heating the substrate to a second temperature higher than the first temperature, wherein the heating of the substrate initiates a static reflow of the metal material deposited on the substrate, stopping the heating of the substrate, and depositing additional metal material on the substrate, initiating a dynamic reflow of the additional metal material deposited on the substrate. RF bias power can be applied during the dynamic reflow to help maintain the temperature of the substrate.

Description

Technical Field

[0001] The implementation of this principle generally relates to the semiconductor processing of semiconductor substrates. Background Technology

[0002] Semiconductor devices, such as ICs (integrated circuits), generally have electronic circuit elements such as transistors, diodes, and resistors, which are integrated onto a single body of semiconductor material such as a wafer or substrate. These various circuit elements are connected by conductive interconnects to form a complete circuit, which can contain millions of individual circuit elements. Interconnects provide electrical connections between the various electronic elements of the integrated circuit and form connections between these circuit elements and external contact elements of the device (e.g., pins for connecting the integrated circuit to other circuits). Interconnects can be built across multiple layers and connected within / between layers by trenches / vias. With the push for increasingly smaller form factors, interconnects must also be scaled down to achieve even smaller form factors for semiconductor devices. Due to their small size, trenches / vias with node structures of 5nm and beyond present challenges during fabrication. Static reflow processes are often used as a method for filling trenches / vias. However, the inventors have found that static reflow processes require multiple cycles, which drastically reduces wafer yield.

[0003] Therefore, the inventors have provided an improved method and apparatus for increasing the yield of wafers requiring gap filling processes. Summary of the Invention

[0004] This article provides methods and apparatus for improving a gap-filling process used to form interconnects on a wafer.

[0005] In some embodiments, a method of filling a structure on a substrate may include: depositing a metal material on the substrate at a first temperature; heating the substrate to a second temperature above the first temperature, wherein the heating of the substrate induces static reflow of the metal material on the substrate; stopping the heating of the substrate; and depositing additional metal material on the substrate, thereby inducing dynamic reflow of the additional metal material on the substrate.

[0006] In some embodiments, the method may further include: applying RF bias power to heat the substrate during the dynamic reflow, wherein the first temperature is from about 0 degrees Celsius to about 70 degrees Celsius, wherein the metal material is a copper-based material, wherein the second temperature is from about 80 degrees Celsius to about 400 degrees Celsius, wherein the second temperature is about 270 degrees Celsius, positioning the substrate at a first position before depositing the metal material on the substrate, positioning the substrate at a second position above the first position before heating the substrate, and moving the substrate from the second position to the first position when heating the substrate stops, wherein the heating of the substrate is from a heating source located below the substrate, heating the substrate to a third temperature above the first temperature and below the second temperature, and after a first period of time, heating the substrate from the third temperature to the second temperature, and / or wherein the first period of time is about 30 seconds.

[0007] In some embodiments, a method of filling a structure on a substrate may include: depositing a metal material on the substrate at a first temperature; heating the substrate to a second temperature above the first temperature to induce a first static reflow having a first reflow rate; heating the substrate to a third temperature above the second temperature to induce a second static reflow having a second reflow rate, wherein the second reflow rate is higher than the first reflow rate; stopping heating the substrate; applying RF bias power to the substrate; and depositing additional metal material on the substrate to induce a dynamic reflow of the additional metal material on the substrate.

[0008] In some embodiments, the method may further include: wherein the first temperature is about 0 degrees Celsius to about 70 degrees Celsius, wherein the first temperature is about room temperature, wherein the metal material is a copper-based material, wherein the second temperature is about 80 degrees Celsius to about 225 degrees Celsius, wherein the third temperature is about 250 degrees Celsius to about 400 degrees Celsius, and / or wherein the third temperature is about 270 degrees Celsius.

[0009] In some embodiments, a non-transitory computer-readable medium storing instructions that, when executed, trigger the execution of a method for filling a structure on a substrate, the method including: depositing a metal material on the substrate at a first temperature; heating the substrate to a second temperature above the first temperature, the heating of the substrate triggering a static reflow of the metal material on the substrate; stopping the heating of the substrate; and depositing additional metal material on the substrate, triggering a dynamic reflow of the additional metal material on the substrate.

[0010] In some embodiments, the non-transitory computer-readable medium may further include: positioning the substrate at a first position before depositing the metal material onto the substrate, positioning the substrate at a second position above the first position before heating the substrate, moving the substrate from the second position to the first position when heat is removed from the substrate, and / or applying RF bias power to heat the substrate during the dynamic reflow.

[0011] Other and further implementation methods are disclosed below. Attached Figure Description

[0012] The embodiments of this principle, which are briefly summarized above and discussed in more detail below, can be understood by referring to the illustrative embodiments of the principle depicted in the accompanying drawings. However, the drawings only illustrate typical embodiments of the principle and should therefore not be considered as limiting, as these principles may allow for other equivalent embodiments.

[0013] Figure 1 The processing chambers of some embodiments based on this principle are described.

[0014] Figure 2 A cross-sectional view depicting a portion of a processing chamber in a processing or deposition position according to some embodiments of this principle.

[0015] Figure 3 A cross-sectional view depicting a portion of a processing chamber in a heating or reflux position according to some embodiments of this principle.

[0016] Figure 4 Methods for filling gaps on a substrate according to some embodiments of this principle are described.

[0017] Figure 5 Cross-sectional views depicting structures for gap filling according to some embodiments of this principle.

[0018] Figure 6 Graphs depicting heating cycles according to some embodiments of this principle.

[0019] For ease of understanding, the same reference numerals are used as much as possible to denote common elements in the figures. These figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be advantageously incorporated into other embodiments without further detail. Detailed Implementation

[0020] This method and apparatus provide a gap-filling process utilizing semi-dynamic reflow. A filler material is deposited onto a structure on a substrate, which is then raised to a static reflow temperature in one or more stages. The filler material is reflowed into the structure over a given period, and the heat source is then removed. Subsequent deposition is performed on the substrate, causing a dynamic reflow process. Advantageously, the semi-dynamic reflow process allows for dynamic metal reflow after static reflow within a single lamp chamber, enabling bottom-up filling of 5nm node structures and smaller. For example, a single-chamber semi-dynamic copper reflow process can provide up to 2 to 3 times or more of yield improvement compared to a multi-cycle static reflow process. The semi-dynamic reflow process can also be used for back-to-line (BEOL) and mid-to-line (MEOL) processes.

[0021] As feature sizes continue to shrink, achieving good gap-filling and electroyield performance using conventional gap-filling methods, such as plasma vapor deposition (PVD) for copper seed crystals followed by electrochemical copper plating (ECP), presents challenges. In some cases at the 5nm node and beyond, copper reflow is chosen as the primary gap-filling solution. The methods and apparatus of this principle enable void-free gap-filling performance with copper-filled materials at the 5nm node and beyond, while still providing a 2 to 3 times or more yield increase compared to multi-cycle static reflow using copper materials. Although copper may be used in the examples for simplicity, these processes can be applied to other materials such as aluminum or cobalt.

[0022] Metal reflow can be achieved through multi-cycle static reflow, which uses a room-temperature metal deposition stage followed by a heating stage and a cooling stage. Multi-cycle static reflow is very time-consuming and reduces wafer yield. Metal reflow can also be achieved through dynamic reflow, where metal deposition and reflow occur simultaneously while the wafer is heated. Dynamic reflow cannot achieve void-free gap filling due to voids at the bottom of vias and line-end agglomeration. The method and apparatus of this principle use semi-dynamic reflow, which employs two reflow methods in a single process—static reflow to fill vias and dynamic reflow to fill trenches. Semi-dynamic reflow not only increases yield but also provides flexibility in temperature variation. Temperature variation is achieved by controlling the time and power of the heating lamps in the processing chamber, thereby achieving balanced control of metal film accumulation and bottom-up filling.

[0023] In some embodiments, a semi-dynamic bottom-up reflow process may include first depositing a layer of metal material on a substrate having at least one structure to be filled. Static reflow of the metal material is achieved by heating the substrate with lamps, which allows the metal material to flow down to the bottom of the structure. Subsequent dynamic reflow is accomplished by keeping the substrate cooling to a minimum before and during the dynamic reflow process. Cooling is minimized by removing backside gas before and during dynamic deposition while gently clamping the wafer to prevent substrate slippage. During the dynamic reflow process, thermal and kinetic energy are maintained at levels sufficient for the mobility of the metal material. Thermal energy is maintained in part by keeping the substrate temperature sufficiently high in the absence of backside gas. Kinetic energy is achieved by using a mid-level substrate bias that helps accelerate metal material ions to bombard the substrate and heats the substrate by converting kinetic energy into thermal energy.

[0024] This document describes an exemplary implementation of the disclosure for a physical vapor deposition (PVD) chamber. However, the methods and apparatus of this principle can also be used in other processing chambers. Figure 1 A PVD chamber (processing chamber 100) suitable for sputtering deposited material on a substrate having a given diameter is illustrated, such as a sputtering processing chamber. In some embodiments, the PVD chamber further includes a collimator 118 disposed within the PVD chamber. The processing chamber 100 typically includes an upper sidewall 102, a lower sidewall 103, a ground adapter 104, and a cover assembly 111, which define a body 105 that surrounds an interior volume 106. The interior volume 106 includes a central portion having approximately the given diameter of the substrate to be processed, and a peripheral portion surrounding the central portion. Furthermore, the interior volume 106 includes an annular region located above the substrate and close to the target, wherein the inner diameter of the annular region is substantially equal to or greater than the diameter of the substrate, such that the main portion of the plasma is positioned above and radially outward from the substrate.

[0025] A connector plate 107 may be disposed between an upper sidewall 102 and a lower sidewall 103. A substrate support 108 is disposed within the internal space 106 of the processing chamber 100. The substrate support 108 may include, for example, an electrostatic chuck (ESC) 151 and a puck 161. The substrate support 108 is configured to support a substrate having a given diameter (e.g., 150 mm, 200 mm, 300 mm, 450 mm, etc.). A substrate transfer port 109 is formed in the lower sidewall 103 for transferring the substrate in and out of the internal space 106. In some embodiments, the processing chamber 100 is configured to deposit, for example, copper, aluminum, or cobalt on a substrate (such as substrate 101). Non-limiting examples of suitable applications include the deposition of a metallic gap-filling material in vias, trenches, or structures.

[0026] A gas source 110 is coupled to the processing chamber 100 to supply processing gas to the internal space 106. In some embodiments, the processing gas may include inert, non-reactive, and reactive gases, if desired. Examples of processing gases that can be supplied by the gas source 110 include, but are not limited to, argon (Ar), helium (He), neon (Ne), nitrogen (N2), oxygen (O2), and water (H2O) vapor. A pumping device 112 is coupled to the processing chamber 100 and communicates with the internal space 106 to control the pressure in the internal space 106. In some embodiments, the pumping device 112 may also be used to remove backside gas from the substrate 101 to minimize cooling of the substrate 101. In some embodiments, the pressure level of the processing chamber 100 may be maintained at approximately 1 Torr or less during deposition. In some embodiments, the pressure level of the processing chamber 100 may be maintained at approximately 500 mTorr or less during deposition. In some embodiments, the pressure level of the processing chamber 100 may be maintained at about 0.01 mTorr to about 300 mTorr during deposition.

[0027] Grounding adapter 104 may support a target, such as target 114. Target 114 is made of a material to be deposited on a substrate. In some embodiments, target 114 may be made of cobalt (Co), copper (Cu), or aluminum (Al), alloys of the above materials, combinations of the above materials, or similar materials. Target 114 may be coupled to a source assembly including a power supply 117 for target 114. In some embodiments, power supply 117 may be an RF power supply coupled to target 114 via matching network 116. In some embodiments, power supply 117 may also be a DC power supply, in which case matching network 116 is omitted. In some embodiments, power supply 117 may include both DC and RF power supplies.

[0028] The magnetron 170 is positioned above the target 114. The magnetron 170 may include a plurality of magnets 172 supported by a substrate 174 connected to a shaft 176 axially aligned with the central axis of the substrate 101 and the processing chamber 100. The magnets 172 generate a magnetic field within the processing chamber 100 near the front surface of the target 114, thus generating plasma. This results in a significant flux of ions bombarding the target 114, triggering sputtering of the target material. The magnets 172 may rotate about the shaft 176 to increase the uniformity of the magnetic field across the surface of the target 114. Examples of magnetrons include electromagnetic linear magnetrons, serpentine magnetrons, helical magnetrons, double-digitated magnetrons, rectangular helical magnetrons, dual-motion magnetrons, etc. Magnet 172 rotates about the central axis of processing chamber 100 within an annular region extending from near the outer diameter of the substrate to near the outer diameter of the internal space 106. Generally, magnet 172 is rotatable such that during rotation of magnet 172, the innermost magnet position is positioned above or outside the diameter of the substrate being processed (e.g., the distance from the axis of rotation to the innermost position of magnet 172 is equal to or greater than the diameter of the substrate being processed).

[0029] The processing chamber 100 further includes an upper shield 113 and a lower shield 120. A collimator 118 is positioned within an internal space 106 between the target 114 and the substrate support 108. In some embodiments, the collimator 118 may be electrically biased to control the ion flux to the substrate and the neutral angle distribution at the substrate, and to increase the deposition rate due to the increased DC bias. Biasing the collimator reduces ion loss to the collimator, advantageously providing a larger ion / neutral species ratio at the substrate. A collimator power supply (not shown) is coupled to the collimator 118 to facilitate biasing the collimator 118. In some embodiments, the collimator 118 may be electrically isolated from grounded chamber components such as a grounding connector 104. For example, as in... Figure 1As depicted, collimator 118 is coupled to upper shield 113.

[0030] In some embodiments, a set of magnets 196 may be positioned adjacent to the grounding connector 104 to help generate a magnetic field that guides ions dislodged from the target 114. The magnetic field generated by this set of magnets 196 may alternatively or in combination prevent ions from impacting the sidewalls of the chamber (or the sidewalls of the upper shield 113) and guide ions perpendicularly through the collimator 118. For example, the set of magnets 196 may be configured to form a magnetic field with substantially vertical magnetic field lines in the peripheral portion. The substantially vertical magnetic field lines advantageously guide ions through the internal space. The set of magnets 196 may include any combination of necessary electromagnets and / or permanent magnets to guide metal ions from the target along a desired trajectory, through the collimator, and toward the center of the substrate support 108. The set of magnets 196 may be fixed or movable to adjust the position of the set of magnets in a direction parallel to the central axis of the chamber.

[0031] RF power supply 180 can be coupled to processing chamber 100 via substrate support 108 to provide bias power between target 114 and substrate support 108. In some embodiments, RF power supply 180 may have a frequency between approximately 400 Hz and approximately 200 MHz, for example, approximately 13.56 MHz. In some embodiments, RF power supply 180 can provide bias power greater than zero watts to approximately 1000 watts. In operation, magnet 172 rotates to form plasma 165 in an annular portion of internal space 106 to sputter target 114. Plasma 165 can be formed above collimator 118 when collimator 118 is present to sputter target 114 above collimator 118. The radius of rotation of magnet 172 is greater than the radius of substrate 101 to ensure that there is minimal or no sputtered material above substrate 101.

[0032] Collimator 118 is positively biased, forcing the sputtered metal material through it. Furthermore, most (if not all) of the neutral sputtered material traveling towards the central region of the collimator may collide with and adhere to the collimator wall. Because the orientation of the neutral metal species cannot be changed, it is advantageous that most (if not all) of the neutral metal species do not deposit on substrate 101. To ensure sufficient space for the trajectory of the sputtered metal ions to change, collimator 118 is positioned at a predetermined height above substrate support 108. In some embodiments, this height is between approximately 400 mm and approximately 800 mm, for example, approximately 600 mm. This height is also chosen to facilitate ion control using a magnetic field below collimator 118, further improving deposition characteristics on substrate 101. To achieve modulation of the magnetic field above collimator 118, collimator 118 may be positioned at a predetermined height below target 114. This height may be between approximately 25 mm and approximately 75 mm, for example, approximately 50 mm. The total distance between the target and the substrate (or the distance between the target and the support surface) is approximately 600 mm to approximately 800 mm.

[0033] In some embodiments, the lower shield 120 may be disposed near the collimator 118 and inside the grounding connector 104 or the upper sidewall 102. The collimator 118 includes a plurality of apertures to guide the flow of gas and / or material within the interior space 106. The collimator 118 may be coupled to a collimator power supply via a processing tool connector 138. A shielding ring 126 may be disposed in the processing chamber 100, adjacent to the lower shield 120 and between the lower shield 120 and the connector plate 107. The substrate 101 (shown as being supported on a lifting pin 140 in an elevated heating or reflow position) is centered relative to the longitudinal axis of the substrate support 108 by alignment and positioning correction between the substrate support 108 and the robot blade (not shown). Thus, the substrate 101 can be housed within the processing chamber 100 and the shielding ring 126 can be radially upwardly centered around the substrate 101 during processing.

[0034] In operation, a robotic blade (not shown) on which a substrate 101 is mounted extends through a substrate transfer port 109. A substrate support 108 can be lowered to transfer the substrate 101 to a lifting pin 140 extending from the substrate support 108. The lifting and lowering of the substrate support 108 can be controlled by a driver 142 coupled to the substrate support 108. The substrate support 108 can be lowered when the lifting pin 140 is raised to a heating or reflow position. Similarly, the substrate 101 can be lowered onto the substrate receiving surface 144 of the substrate support 108 by lowering the lifting pin 140 and raising the substrate support 108 to a processing or deposition position. Sputter deposition can be performed on the substrate 101 while it is positioned on the substrate receiving surface 144 of the substrate support 108. During processing, the deposition ring 136 can be electrically insulated from the substrate 101. Therefore, the substrate receiving surface 144 may include a height greater than the height of the portion of the deposition ring 136 adjacent to the substrate 101, thereby preventing the substrate 101 from contacting the deposition ring 136.

[0035] After sputtering deposition, the substrate 101 can be raised to a position spaced apart from the substrate support 108 using the lifting pin 140. The raised position can be above one or both of the shielding ring 126 and the reflector ring 148, adjacent to the adapter plate 107. The adapter plate 107 includes one or more lamps 150 coupled to the adapter plate 107 at a position between the lower surface of the reflector ring 148 and a recess 152 of the adapter plate 107. The lamps 150 provide light energy and / or radiant energy of visible or near-visible wavelengths, such as in the infrared (IR) and / or ultraviolet (UV) spectrum. The energy from the lamps 150 is concentrated radially inward toward the back side (i.e., the lower surface) of the substrate 101 to heat the substrate 101 and the material deposited on it. The reflective surfaces on the chamber components surrounding substrate 101 act to concentrate energy toward the back side of substrate 101 and away from other chamber components where energy would be lost and / or not utilized. After substrate 101 is brought to a predetermined temperature, substrate 101 is lowered to a position on the substrate receiving surface 144 of substrate support 108. Substrate 101 can be removed from processing chamber 100 through substrate transfer port 109 for further processing. Substrate 101 can be maintained within a predetermined temperature range, such as, but not limited to, below 600 degrees Celsius.

[0036] Controller 198 controls the operation of processing chamber 100 by directly controlling multiple processing chambers, or alternatively by controlling a computer (or controller) associated with the multiple processing chambers and processing chamber 100. In operation, controller 198 enables the collection of data and feedback from individual chambers and systems to optimize the performance of processing chamber 100. Controller 198 generally includes a central processing unit (CPU) 160, memory 158, and support circuitry 162. CPU 160 can be any form of general-purpose computer processor capable of being used in an industrial environment. Support circuitry 162 is conventionally coupled to CPU 160 and may include cache memory, clock circuitry, input / output subsystems, power supply, etc. Software programs (such as those described above) can be stored in memory 158 and, when executed by CPU 160, transform CPU 160 into a dedicated computer (controller 198). Software programs can also be stored and / or executed by a second controller (not shown) located at a remote end of processing chamber 100.

[0037] Memory 158 is in the form of a computer-readable storage medium containing instructions that, when executed by CPU 160, facilitate the operation of semiconductor processes and devices. The instructions in memory 158 are in the form of a program product, such as a program that implements the methods of this principle. Program code may conform to any of many different programming languages. In one example, the disclosure herein can be implemented as a program product stored on a computer-readable storage medium for use by a computer system. The program product defines the functionality of several aspects, including the methods described herein. Exemplary computer-readable storage media include, but are not limited to: non-writable storage media (e.g., read-only memory devices within a computer, such as CD-ROM discs readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory) that permanently store information; and writable storage media (e.g., floppy disks within a floppy disk drive, or hard disk drives, or any type of solid-state random access semiconductor memory) that store modifiable information. Such computer-readable storage media, when carrying computer-readable instructions that direct the functionality of the methods described herein, are aspects of this principle.

[0038] During processing, material is sputtered from target 114 and deposited onto the surface of substrate 101. Target 114 and substrate support 108 are biased relative to each other via power supply 117 or RF power supply 180 to maintain the plasma formed by the process gas supplied by gas source 110. In some embodiments, the DC pulse bias power applied to collimator 118 also helps control the ratio of ions and neutral matter passing through collimator 118, advantageously enhancing trench sidewall and bottom filling capabilities. Ions from the plasma are accelerated toward and strike target 114, causing material to be ejected from target 114. The ejected target material and process gas form a layer with the desired composition on substrate 101. Substrate 101 is then raised to a heating or reflow position and heated by lamp 150 during the static reflow portion of the process. Lamp 150 is then turned off, backside gas is pumped out using pumping device 112, and substrate 101 is lowered to a processing or deposition position. Then, during the dynamic reflow portion of the process, the substrate 101 is heated using RF bias power supplied by RF power supply 180.

[0039] Figure 2 The processing chamber 100 is in the processing or deposition position (the substrate 101 is in a lowered position and is not shown). Figure 1 A cross-sectional view 200 shows a portion of the substrate support 108, including an ESC 151 and a lamp 150. When the lamp 150 is in operation, it radiates infrared or ultraviolet heat. The substrate 101 is supported by a disk 161 interfaced with the ESC 151. When the substrate 101 is in the heating or reflow position, a lifting pin 140 allows the substrate 101 to be lifted away from the substrate receiving surface 144 of the disk 161. Figure 3 In the middle, cross-sectional view 300 depicts the substrate 101 and substrate support 108 in the heating or reflow position (the substrate 101 is in the raised position, such as...). Figure 1 (As shown). In the reflow position, as the lifting pin 140 raises 304 the substrate 101, the substrate support 108 lowers 302, exposing the lower surface 306 of the substrate 101 to thermal radiation 308 from the lamp 150.

[0040] Figure 4 This is a method 400 for filling a structure on a substrate according to some embodiments. In block 402, a metallic material is deposited on the substrate at a first temperature. In some embodiments, the metallic material may be a copper-based material, an aluminum-based material, or a cobalt-based material, etc. For simplicity, copper-based materials may be used in some of the following examples, but this is not intended to be limiting in any way. In some embodiments, the deposition of the metallic material may occur at a first temperature of approximately room temperature. In some embodiments, the first temperature may range from approximately 0 degrees Celsius to approximately 70 degrees Celsius. In some embodiments, the first temperature is approximately 40 degrees Celsius. Figure 5 In the cross-sectional view 500A, a structure 502 on a substrate is illustrated, having a metallic material 504 deposited on the substrate at a first temperature. In some embodiments, when the substrate is subjected to... Figure 2 When the treatment or deposition location (lowering position) is shown, the deposited metallic material 504 is deposited. Figure 6 View 600 of the graph depicts the process temperature profile of some embodiments of method 400 via curve 602. "Cold" or room temperature deposition in some embodiments of method 400 is indicated by deposition period 604. In some embodiments, deposition period 604 can be from approximately 15 seconds to approximately 60 seconds, depending on the amount of metallic material to be deposited.

[0041] exist Figure 4 In block 404, the substrate is heated to a second temperature above the first temperature to induce static reflow of the metal material. Before heating the metal material, the substrate can be moved to a heating or reflow location different from the processing or deposition location (e.g., ...). Figure 1 (The elevation position shown). Figure 6 The second temperature heating period 608 can range from approximately 10 seconds to approximately 120 seconds. In some embodiments, for copper-based materials, the second temperature heating period 608 is from approximately 20 seconds to approximately 30 seconds. In some embodiments based on copper materials, the second temperature can range from approximately 80 degrees Celsius to approximately 400 degrees Celsius. When the substrate contains low-k materials, heating the substrate to above 400 degrees Celsius may damage the low-k materials. In some embodiments based on copper materials, the second temperature can be approximately 270 degrees Celsius. In some embodiments based on aluminum materials, the second temperature can range from approximately 80 degrees Celsius to approximately 400 degrees Celsius. In some embodiments based on cobalt materials, the second temperature can range from approximately 80 degrees Celsius to approximately 550 degrees Celsius.

[0042] Heating the substrate triggers a static reflow of the metal material deposited on the substrate. The inventors have discovered that the second temperature should be sufficient to maintain the fluidity of the metal material and can be varied depending on the type of metal material being reflowed. Figure 5 Cross-sectional view 500A depicts the static reflow filling 506 of structure 502 with previously deposited metallic material 504. The heating of the substrate and the maintenance of the substrate temperature can be achieved by... Figure 1 The processing chamber 100 is equipped with lamps 150. The lamp power on-time and lamp power level can be used to adjust the substrate temperature. Lamp 150 can provide direct thermal radiation (infrared and / or ultraviolet radiation) as well as indirect thermal radiation, which is reflected from the substrate receiving surface 144 of the disk 161 of ESC 151.

[0043] In some embodiments, heating the substrate to the second temperature can be completed in more than one stage. Curve 602 depicts a third temperature heating period 606 at a third temperature below the second temperature and above the first temperature. In some embodiments, the third temperature can be from about 80 degrees Celsius to about 225 degrees Celsius. In some embodiments, the third temperature can be from about 150 degrees Celsius to about 200 degrees Celsius. In some embodiments, the third temperature can be about 170 degrees Celsius. Using multi-stage heating allows the metallic material to flow slowly into the structure, allowing for continuous and uniform flow without interruption. The third temperature should be sufficient to maintain the fluidity of the metallic material. The third temperature can be adjusted based on the type of metallic material being reflowed. In some embodiments, two or more temperature stages can occur between the first and second temperatures. In some embodiments, the third temperature heating period 606 can range from about 10 seconds to about 120 seconds or longer. In some embodiments, the third temperature heating period 606 is about 30 seconds. Intermediate heating periods 612, 614 have a duration that depends on the heating rate between the first, second, and third temperatures. Using multi-stage heating allows the metal material to flow slowly and evenly without interruption, while higher temperatures allow for a smoother transition to faster reflow.

[0044] Stop heating the substrate at block 406. Figure 6 In some embodiments, the heat removal point is indicated by heat removal point 616. In some embodiments, the heat removal is achieved by removing power to lamp 150 (see...). Figure 3 The heating of the substrate is then stopped. In some embodiments, the back-side gas can be removed when heating is stopped to minimize substrate cooling before and during dynamic reflow. The back-side gas can be... Figure 1 The pumping device 112 of the processing chamber 100 is removed. In block 408, additional metal material is deposited on the substrate. The deposition on the heated substrate triggers dynamic reflow of the additional metal material onto the substrate. In some embodiments, the substrate is moved from the heating or reflow position when heating stops, and moved to the processing or deposition position before the deposition of additional metal material onto the substrate begins. Figure 6 In view 600, the repositioning period 618 is marked. During the repositioning period, the substrate may undergo some cooling. Keeping the repositioning period 618 to a minimum helps maintain the substrate temperature and ensures that the dynamic reflow period 610 is maximized. Figure 5View 500B depicts deposition 508 occurring on structure 502 when the substrate is hot. Dynamic reflow occurs, and additional metal material flows into structure 502 to fill structure 502 510. The inventors have discovered that substrate cooling should be kept to a minimum during the dynamic reflow process. This minimization is achieved by removing backside gas before and during dynamic deposition.

[0045] The inventors also discovered that during the dynamic reflow process, thermal and kinetic energy should be maintained at a level sufficient for the fluidity of the metal material. Thermal energy is maintained in part by keeping the substrate temperature sufficiently high in the absence of backside gas. In some embodiments based on copper materials, dynamic reflow (simultaneous deposition and reflow) continues as long as the substrate temperature is between approximately 80°C and approximately 400°C. In some embodiments based on copper materials, dynamic reflow continues as long as the substrate temperature is between approximately 150°C and approximately 400°C. In some embodiments based on cobalt materials, dynamic reflow continues as long as the substrate temperature is between approximately 80°C and approximately 550°C.

[0046] Kinetic energy is achieved by using an intermediate-order substrate bias, which helps to accelerate metal material ions to bombard the substrate and heat the substrate by converting kinetic energy into heat energy. In some embodiments based on copper-based metal materials, the intermediate-order RF bias power is about 200 watts, and the etch-to-deposition (ED) ratio is about 0.40 to about 0.60. In some embodiments, the intermediate-order RF bias power is about 5 watts to about 1000 watts. In some embodiments, the intermediate-order RF bias power is about 5 watts to about 700 watts. In some embodiments, the RF bias frequency is about 2 MHz to about 200 MHz. In some embodiments, the RF bias frequency is about 13.56 MHz. In some embodiments, Figure 1 The RF power supply 180 of the processing chamber 100 can provide RF bias power to the substrate 101 to enhance the kinetic energy during deposition in the dynamic reflow process. The inventors have discovered that if the RF bias power is too high, damage can occur at the edges (corners) of the structure's openings. The inventors have also discovered that if the RF bias power is too low, the reflow profile will be poor. In effect, the RF bias power provides plasma heating of the substrate to help maintain the wafer temperature during dynamic reflow.

[0047] Implementations based on this principle may be carried out in hardware, firmware, software, or any combination thereof. Implementations may also be carried out as instructions stored using one or more computer-readable media, which may be read and executed by one or more processors. The computer-readable media may include any mechanism for storing or transmitting information in a machine-readable form (e.g., a computing platform or a “virtual machine” operating on one or more computing platforms). For example, the computer-readable media may include any suitable form of volatile or non-volatile memory. In some implementations, the computer-readable media may include non-transitory computer-readable media.

[0048] While the foregoing describes an implementation of this principle, other and further implementations of this principle can be designed without departing from its basic scope.

Claims

1. A method of filling a structure on a substrate, comprising: depositing a first metal material on the substrate at a first temperature; heating the substrate to a second temperature higher than the first temperature; after a first period of time, heating the substrate to a third temperature higher than the second temperature, the heating of the substrate to the third temperature inducing a static reflow of the first metal material on the substrate; stopping heating of the substrate; and depositing a second metal material on the substrate, inducing a dynamic reflow of the second metal material on the substrate.

2. The method of claim 1, further comprising: applying RF bias power to heat the substrate during the dynamic reflow.

3. The method of claim 1, wherein the first temperature is 0 degrees Celsius to 70 degrees Celsius.

4. The method of claim 1, wherein the first metal material and the second metal material are copper-based materials.

5. The method of claim 4, wherein the third temperature is 80 degrees Celsius to 400 degrees Celsius.

6. The method of claim 5, wherein the third temperature is 270 degrees Celsius.

7. The method of claim 1, further comprising: positioning the substrate at a first position prior to depositing the first metal material on the substrate; positioning the substrate at a second position higher than the first position prior to heating the substrate; and moving the substrate from the second position to the first position when stopping heating of the substrate.

8. The method of claim 1, wherein the heating of the substrate is from a heating source located below the substrate.

9. The method of claim 1, wherein the first period of time is 30 seconds.

10. A method of filling a structure on a substrate, comprising: depositing a first metal material on the substrate at a first temperature; heating the substrate to a second temperature higher than the first temperature, inducing a first static reflow having a first reflow rate; heating the substrate to a third temperature higher than the second temperature, inducing a second static reflow having a second reflow rate, wherein the second reflow rate is higher than the first reflow rate; stopping heating of the substrate; applying RF bias power to the substrate; and depositing a second metal material on the substrate, inducing a dynamic reflow of the second metal material on the substrate.

11. The method of claim 10, wherein the first temperature is 0 degrees Celsius to 70 degrees Celsius.

12. The method of claim 11, wherein the first temperature is room temperature.

13. The method of claim 10, wherein the first metal material and the second metal material are copper-based materials.

14. The method of claim 13, wherein the second temperature is 80 degrees Celsius to 225 degrees Celsius.

15. The method of claim 13, wherein the third temperature is 250 degrees Celsius to 400 degrees Celsius.

16. The method of claim 15, wherein the third temperature is 270 degrees Celsius. ​ ​ ​ 17. A non-transitory computer readable medium having instructions stored thereon that, when executed, result in performing a method for filling a structure on a substrate, the method comprising: depositing a first metal material on the substrate at a first temperature; heating the substrate to a second temperature that is higher than the first temperature; heating the substrate to a third temperature that is higher than the second temperature, the heating of the substrate to the third temperature resulting in static reflow of the first metal material on the substrate; stopping heating the substrate; and depositing a second metal material on the substrate, resulting in dynamic reflow of the second metal material on the substrate.

18. The non-transitory computer readable medium of claim 17, further comprising: positioning the substrate at a first position prior to depositing the first metal material on the substrate; positioning the substrate at a second position that is higher than the first position prior to heating the substrate; and moving the substrate from the second position to the first position when heat is removed from the substrate. applying RF bias power to heat the substrate during the dynamic reflow.

19. The non-transitory computer readable medium of claim 18, wherein the first position is a first temperature and the second position is a second temperature that is higher than the first temperature.

19. The non-transitory computer-readable medium of claim 17, further comprising:

20. The non-transitory computer readable medium of claim 19, wherein the first temperature is room temperature and the second temperature is a temperature that is higher than room temperature.

21. The non-transitory computer readable medium of claim 20, wherein the first temperature is room temperature and the second temperature is a temperature that is higher than room temperature.

22. The non-transitory computer readable medium of claim 21, wherein the first temperature is room temperature and the second temperature is a temperature that is higher than room temperature.

23. The non-transitory computer readable medium of claim 22, wherein the first temperature is room temperature and the second temperature is a temperature that is higher than room temperature.

24. The non-transitory computer readable medium of claim 23, wherein the first temperature is room temperature and the second temperature is a temperature that is higher than room temperature.

25. The non-transitory computer readable medium of claim 24, wherein the first temperature is room temperature and the second temperature is a temperature that is higher than room temperature.

26. The non-transitory computer readable medium of claim 25, wherein the first temperature is room temperature and the second temperature is a temperature that is higher than room temperature.

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