Covering disk

Abstract

A shutter disk comprising one or more of titanium (Ti), barium (Ba), or cerium (Ce) for physical vapor deposition (PVD) is described, the shutter disk allowing for adhesion to minimize outgassing and control defects during etching of a substrate. The shutter disk incorporates a getter material that is highly selective for reactant gas molecules including O2, CO, CO2, and water.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to electronic devices and more particularly to under bump metallization in wafer-level packaging or flip-chip packaging.

[0002] Prior Art

[0003] During the evolution of semiconductor manufacturing, different packaging technologies have been utilized. Wafer-level manufacturing and flip-chip packaging technologies for electronic devices are at the forefront of miniaturization initiatives.

[0004] The goal of semiconductor packaging is to achieve shorter electronic paths to increase speed, reduce power consumption, improve device functionality, and reduce costs. Underbump metallization (UBM) is required to connect the die to the substrate using solder bumps for flip-chip packaging. The UBM bond of an integrated circuit (IC) is typically an aluminum or copper pad. This is an essential process step for the reliability of electronic packaging.

[0005] Several options can achieve under-bump metallization (UBM). Dry vacuum sputtering methods combined with electroplating are the most commonly used methods and involve multiple metal layers that are sputtered in a high-temperature evaporation system. The final layer of many IC bond pads typically includes aluminum, aluminum / silicon, aluminum / silicon / copper, or copper. Because wire bonding technology forms an acceptable connection through the commonly present oxide layer, aluminum is suitable for conventional wire bonding interconnects. However, aluminum is not solderable, wettable, or bondable to the bumps and solder materials used in reflow. The UBM layer produces a good bond to the aluminum pad, hermetically seals the aluminum, and prevents potential metal diffusion into the IC package.

[0006] Aluminum oxidizes almost immediately when exposed to the environment, so the first challenge in the UBM process is removing the native oxide layer from the aluminum IC pads. Therefore, a pre-cleaning step is necessary in the UBM process to remove the native oxide from the metal contact pads before the barrier layer is deposited. However, during the pre-cleaning process, outgassing molecules and species are generated, thereby re-contaminating the clean metal surface and causing high contact resistance that can affect IC performance.

[0007] Therefore, there is a need for an improved under-bump metallization method for flip-chip packaging and wafer-level packaging. Summary of the Invention

[0008] One or more embodiments of the present disclosure relate to a processing method that includes depositing a thickness of a getter material on a wall of a processing chamber, and etching a substrate in the processing chamber using a plasma to remove native oxide and form a cleaned substrate, wherein etching the substrate releases outgassing molecules chemically bound to the getter material.

[0009] Additional embodiments of the present disclosure relate to a processing tool comprising: a pre-clean chamber having a substrate support therein; a buffer station; a robot configured to enter and exit the pre-clean chamber and the buffer station; and a controller coupled to the pre-clean chamber, the buffer station, and the robot, the controller having one or more configurations selected from the group consisting of: depositing a getter material, etching the substrate, or depositing a barrier layer.

[0010] Further embodiments of the present disclosure relate to a non-transitory computer-readable medium comprising instructions that, when executed by a controller of a processing chamber, cause the processing chamber to: deposit a getter material on a wall of the processing chamber; and etch a substrate in the processing chamber using a plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more particular description of the present disclosure, briefly summarized above, may be obtained by reference to embodiments, certain of which are illustrated in the accompanying drawings, so that the above-described features of the present disclosure may be understood in detail. It will be noted, however, that the drawings illustrate only typical embodiments of the present disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0012] Figure 1 a flowchart depicting a processing method according to one or more embodiments;

[0013] Figure 2 depicts a processing chamber according to one or more embodiments;

[0014] Figure 3 depicts a processing chamber according to one or more embodiments;

[0015] Figure 4 depicts a processing chamber according to one or more embodiments; and

[0016] Figure 5 A processing tool according to one or more embodiments is depicted. DETAILED DESCRIPTION

[0017] Before describing several exemplary embodiments of the present disclosure, it should be understood that the present disclosure is not limited to the details of the architecture or process steps described in the following description, and the present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0018] Many of the details, dimensions, angles, and other features shown in the accompanying drawings illustrate only specific embodiments. Therefore, other embodiments may have other details, components, dimensions, angles, and features without departing from the spirit and scope of the present disclosure. In addition, further embodiments of the present disclosure may be practiced without some of the details described below.

[0019] As used in this specification and the appended claims, the term "substrate" refers to a surface or portion of a surface on which a process is performed. Unless the context clearly indicates otherwise, those skilled in the art will understand that a substrate may also refer to only a portion of the substrate. Furthermore, references to deposition on a substrate may refer to both a bare substrate and a substrate having one or more films or features deposited or formed thereon.

[0020] As used herein, "substrate" refers to any substrate or material surface formed on a substrate on which film processing is performed during a manufacturing process. For example, substrate surfaces on which processing may be performed include materials such as silicon, silicon oxide, strained silicon, silicon-on-insulator (SOI), carbon-doped silicon oxide, amorphous silicon, doped silicon, germanium, gallium arsenide, glass, sapphire, and any other material such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Without limitation, substrates include semiconductor wafers. The substrate may be exposed to pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, electron beam cure, and / or bake the substrate surface. In addition to film processing directly on the surface of the substrate itself, any film processing step disclosed in this disclosure may also be performed on underlying layers formed on the substrate, as described in more detail below, and the term "substrate surface" is intended to include such underlying layers as indicated by the context. Thus, for example, where a film / layer or portion of a film / layer is already deposited on a substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0021] As used in this specification and the appended claims, the terms "reactive compound," "reactive gas," "reactive species," "precursor," "process gas," and the like are used interchangeably to refer to a substance having a species capable of reacting with a substrate surface or a material on the substrate surface in a surface reaction (e.g., chemisorption, oxidation, reduction). For example, a first "reactive gas" may simply adsorb on the surface of the substrate and be available for further chemical reaction with a second reactive gas.

[0022] Significant efforts have been made to reduce polymer outgassing during under-bump metallization (UBM), such as temperature control and RF power adjustment. In one or more embodiments, coating the inner shield or walls of the processing chamber with one or more of titanium (Ti), barium (Ba), or cerium (Ce) by a gluing method helps absorb outgassing molecules. As used herein, the term "gluing" refers to sputtering of a getter material such that the material adheres to the walls of the processing chamber, thereby forming a layer of the getter material on the walls.

[0023] In one or more embodiments, the concentration of outgassing molecules in the processing chamber can be advantageously significantly reduced. Thus, in one or more embodiments, recontamination of metal contact surfaces is minimized, thereby helping to maintain low contact resistance for better electronic device performance.

[0024] Embodiments of the present disclosure provide a shutter disk comprising one or more of titanium (Ti), barium (Ba), or cerium (Ce) for physical vapor deposition (PVD) that allows for adhesion to minimize outgassing and control defects during etching of a substrate. One or more embodiments provide improved and / or increased service life of a process kit.

[0025] In one or more embodiments, it has been observed that adhering a gas getter material to / in a processing chamber, such as a pre-clean chamber, reduces the concentration of outgassing molecules by at least two orders of magnitude. This observed result is superior to other methods, such as increasing pumping speed and improving gas conductivity.

[0026] Embodiments of the present disclosure incorporate getter materials that are highly selective for reactive gas molecules such as oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), and water (H2O). These reactive gas molecules can be detrimental to metal contact resistance in PVD deposition equipment. Certain embodiments advantageously provide titanium (Ti), barium (Ba), or cerium (Ce) shutter disks that minimize shield outgassing, extend shield kit life, and prevent recontamination of metal surfaces as getter materials that absorb outgassing molecules including oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), and water (H2O) during processing, are capable of withstanding high temperatures, and / or exhibit minimal warping during processing.

[0027] Embodiments of the present disclosure do not require chamber hardware modifications, but instead utilize a shutter disk containing or including a getter material. In one or more embodiments, the shutter disk is transferred to the processing chamber, and RF power is used to perform a sputtering process, thereby sputtering the getter material onto the sides of the processing chamber. In one or more embodiments, the shutter disk is insensitive to noble gases such as argon (Ar) and helium (He), and therefore, the noble gas molecules have limited impact on the physical plasma sputtering effects during the pre-clean process.

[0028] Reference Figures 1 to 4 , one or more embodiments relate to a method 100 of processing a substrate. Figure 1 The method in FIG is a representative diagram of a physical vapor deposition (PVD) process. As used herein, the term "physical vapor deposition" or alternatively "sputtering" refers to a deposition process for metals and related materials in the manufacture of semiconductor integrated circuits. The use of sputtering has been extended to depositing metal layers on the sidewalls of high aspect ratio holes such as through-holes or other vertical interconnect structures. Plasma sputtering can be accomplished using either DC sputtering or RF sputtering. Plasma sputtering typically includes a magnetron positioned at the back of a sputtering target, the magnetron including two magnets with opposite poles magnetically coupled at their backs by a yoke to project a magnetic field into the processing volume to increase the density of the plasma and enhance the sputtering rate from the front of the target. The magnets used in the magnetron are typically closed loop for DC sputtering and open loop for RF sputtering.

[0029] In plasma-enhanced substrate processing systems, such as physical vapor deposition (PVD) chambers, high power density PVD sputtering with a high magnetic field and high DC power can generate high energy at the sputtering target and cause the surface temperature of the sputtering target to increase significantly. The sputtering target is cooled by contacting a cooling fluid with the target backing plate. In plasma sputtering, as commonly practiced commercially, a target of material to be sputtered is sealed into a vacuum chamber containing the wafer to be coated. An inert gas, such as argon (Ar), is allowed to enter this chamber. When a negative DC bias of several hundred volts is applied to the target while the chamber walls or shields are held at ground, the inert gas is excited into a plasma. Positively charged inert gas ions are attracted to the high-energy, negatively biased target and sputter target atoms from the target.

[0030] In one or more embodiments, at operation 10, a getter material 204 is deposited on at least one wall of the processing chamber 200. In one or more embodiments, the getter material 204 is deposited on at least one wall of the processing chamber 200 to a thickness 202. In one or more embodiments, the thickness 202 is greater than or equal to 10 nm, including a range from about 10 nm to about 100 μM. In one or more embodiments, the getter material 206 includes one or more of titanium (Ti), barium (Ba), or cerium (Ce). In one or more embodiments, the getter material 204 is obtained by sputtering the shutter disk 206. In one or more embodiments, the sputtering process includes exposing the shutter disk 206 to a plasma 208. In one or more embodiments, the plasma 208 includes an inert plasma. In some embodiments, the plasma 208 includes one or more of argon (Ar) or helium (He).

[0031] In one or more embodiments, the plasma 208 can be generated remotely or within the processing chamber 200. In one or more embodiments, the plasma 208 is an inductively coupled plasma (ICP) or a capacitively coupled plasma (CCP). Any suitable power can be used and depends, for example, on the reactants or other process conditions. In some embodiments, the plasma 208 is generated at a plasma power ranging from about 10 W to about 3000 W. In some embodiments, the plasma 208 is generated at a plasma power less than or equal to about 3000 W, less than or equal to about 2000 W, less than or equal to about 1000 W, less than or equal to about 500 W, or less than or equal to about 250 W.

[0032] In one or more embodiments, the shutter disk 206 includes one or more of titanium (Ti), barium (Ba), or cerium (Ce). In a specific embodiment, the shutter disk 206 includes titanium (Ti) and, when sputtered, releases the getter material 204 including titanium (Ti), causing titanium to be deposited on at least one wall of the processing chamber 200.

[0033] In one or more embodiments, the shutter disk 206 is then moved or transferred to a buffer station at operation 20. In some embodiments, the buffer station is located within the processing chamber 200. In other embodiments, the buffer station is located in an adjacent chamber. In one or more embodiments, the shutter disk 206 is transferred by a robot. In one or more embodiments, the substrate 209 is then positioned within the processing chamber 200 at operation 30.

[0034] In one or more embodiments, substrate 209 includes one or more of a silicon layer 210, an oxide layer 212, a metal layer 214, a polymer layer 216, or a native oxide layer 218. In one or more embodiments, oxide layer 212 includes an aluminum oxide layer. In one or more embodiments, metal layer 214 includes one or more of aluminum (Al) or copper (Cu). In one or more embodiments, polymer layer 216 includes one or more of polyimide or polybenzoxazole.

[0035] In one or more embodiments, at operation 40, a substrate 209 is etched in the processing chamber 200. In one or more embodiments, the substrate 209 is etched by a plasma 208. In one or more embodiments, the plasma 208 comprises an inert plasma. In some embodiments, the plasma 208 comprises one or more of argon (Ar) or helium (He). In some embodiments, the plasma 208 is the same as the plasma used to sputter the collector material 204 onto at least one sidewall of the processing chamber. In other embodiments, the plasma 208 is different from the plasma used to sputter the collector material 204.

[0036] Without wishing to be bound by theory, during etching of the polymer layer 216 of the substrate 209, the substrate 209 releases outgassing molecules, such as 220, 222, 224, and 226. In one or more embodiments, the outgassing molecules are absorbed by the gas getter material 204 deposited on the side of the processing chamber 200. In one or more embodiments, the outgassing molecules include one or more of oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), or water (H2O). Figure 4 As shown, because the getter material is capable of absorbing outgassing molecules, the concentration of outgassing molecules in the processing chamber is significantly reduced, and thus recontamination of the metal contact surface 214 of the substrate 206 is minimized to maintain low contact resistance for better electronic device performance.

[0037] In one or more embodiments, the amount of outgassing molecules from the substrate 209 is reduced to less than or equal to about 10% of the outgassing molecules from a substrate in a processing chamber that does not include a getter material. In one or more specific embodiments, the amount of outgassing carbon monoxide (CO) from the substrate 209 is reduced to less than or equal to about 10% of the outgassing carbon monoxide (CO) from a substrate in a processing chamber that does not include a getter material.

[0038] Figure 5 A processing tool 300 is shown in accordance with one or more embodiments of the present disclosure. Figure 5The embodiment shown is merely a representation of one possible configuration and should not be considered to limit the scope of the present disclosure. For example, in some embodiments, the processing tool 300 has a different number of processing chambers 302, buffer stations 310, and / or one or more of the robot 308 configurations than the embodiment shown.

[0039] The exemplary processing tool 300 includes a processing chamber 302, such as a pre-clean chamber, having multiple sides. The processing chamber 302 is shown as having a first side 303a, a second side 303b, a third side 303c, and a fourth side 303d. Although four sides are shown, those skilled in the art will appreciate that any suitable number of sides may be present for the processing chamber 302, depending on, for example, the overall configuration of the processing tool 300. In some embodiments, the processing chamber 302 has three sides, four sides, five sides, six sides, seven sides, or eight sides.

[0040] The processing chamber 302 has a robot 308 positioned therein. The robot 308 can be any suitable robot capable of moving wafers during processing. In certain embodiments, the robot 308 includes a first arm 309a and a second arm 309b. The first arm 309a and the second arm 309b can move independently of the other arms. The first arm 309a and the second arm 309b can move in the xy plane and / or along the z-axis. In certain embodiments, the robot 308 includes a third arm (not shown) or a fourth arm (not shown). Each arm can move independently of the other arms.

[0041] The processing tool 300 may also include one or more buffer stations 310 coupled to the first side 303a of the processing chamber 302. The buffer stations 310 may perform the same or different functions. For example, a buffer station may hold a cassette of wafers that have been processed and returned to the starting cassette, or one of the buffer stations may hold unprocessed wafers that are moved to another buffer station after processing. In certain embodiments, one or more of the buffer stations is configured to pre-treat, pre-heat, or clean the wafers before and / or after processing.

[0042] The processing tool 300 may also include one or more slit valves 312 between the processing chamber 302 and the buffer station 310. The slit valves 312 may be opened and closed to isolate the internal volume within the processing chamber 302. For example, if the processing chamber 302 generates plasma during processing, it may be beneficial for the processing chamber to have the slit valves closed to prevent the stray plasma from damaging a robot in the transfer station.

[0043] The robot 308 may be used to move wafers or cassettes into and out of the buffer station 310. The wafers or cassettes may be moved within the processing tool 300 by the robot 308. In one or more embodiments, the robot 308 moves the shutter disk into and out of the processing chamber 302 to the buffer station 310.

[0044] A controller 314 may be provided and coupled to the various components of the processing tool 300 to control the operation of these components. The controller 314 may be a single controller that controls the entire processing tool 300, or multiple controllers that control individual portions of the processing tool 300. For example, the processing tool 300 may include separate controllers for each of the processing chamber 302, the buffer station 310, and the robot 308.

[0045] In certain embodiments, the processing chamber 302 further includes a controller 314 coupled to the plurality of substantially coplanar support surfaces 304. In one or more embodiments, the controller 314 controls the speed at which the substrate support assembly 304 moves.

[0046] In certain embodiments, the controller 314 includes a central processing unit (CPU) 316, memory 318, input / output (I / O) 320, and support circuitry 322. The controller 314 may control the processing tool 300 directly or via computers (or controllers) associated with specific processing chambers and / or support system components.

[0047] The controller 314 can be any of a variety of general-purpose computer processors that can be used in an industrial environment to control various chambers and sub-processors. The memory 318 or computer-readable medium of the controller 314 can be one or more readily available memories, such as local or remote random access memory (RAM), read-only memory (ROM), floppy disk, hard disk, optical storage media (e.g., compact disk or digital video disk), pen drive, or any other form of digital storage. The memory 318 can hold a set of instructions operable by the processor (CPU 316) to control parameters and components of the processing tool 300.

[0048] Support circuits 322 are coupled to the CPU 316 for supporting the processor in a conventional manner. These circuits include caches, power supplies, clock circuits, input / output circuitry and subsystems, and the like. One or more processes may be stored in the memory 318 as software routines that, when executed or implemented by the processor, cause the processor to control the operation of the processing tool 300 or individual processing chambers in the manner described herein. Such software routines may also be stored and / or executed by a second CPU (not shown) that is remote from the hardware controlled by the CPU 316.

[0049] Some or all of the processes and methods of the present disclosure may also be implemented in hardware. Thus, the processes may be implemented in software and executed in hardware using a computer system, such as, for example, an application specific integrated circuit or other type of hardware implementation, or a combination of software and hardware. When executed by a processor, the software routines transform a general-purpose computer into a specific purpose computer (controller) that controls chamber operations to perform the processes.

[0050] In certain embodiments, the controller 314 has one or more configurations to execute individual processes or sub-processes to perform the method. The controller 314 can be connected to and configured to operate intermediate components to perform the functions of the method. For example, the controller 314 can be connected to and configured to control one or more of a gas valve, an actuator, a motor, a slit valve, a vacuum control, or other components.

[0051] References throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments," or "an embodiment" mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment," or "in an embodiment" that appear in various places throughout this specification are not necessarily referring to the same embodiment of the present disclosure. Furthermore, in one or more embodiments, the particular features, structures, materials, or characteristics are combined in any suitable manner.

[0052] Although the present disclosure has been described herein with reference to specific embodiments, those skilled in the art will appreciate that the embodiments are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations may be made to the methods and apparatus of the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is intended to encompass modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A treatment method, comprising: transferring a shutter disk to a processing chamber, the shutter disk comprising a getter material; sputtering the shutter disk to deposit a thickness of the getter material on a wall of the processing chamber; etching a substrate in the processing chamber using a plasma to remove native oxide and form a cleaned substrate, wherein etching the substrate releases outgassing molecules that chemically bond to the getter material; as well as The shutter disk is removed from the processing chamber. 2 . The method of claim 1 , further comprising depositing a barrier layer on the cleaned substrate. 3 . The method of claim 2 , wherein the barrier layer comprises one or more of titanium (Ti) or copper (Cu).

4. The method of claim 1, wherein the gas getter material comprises one or more of titanium, barium, or cerium. The method of claim 1 , wherein the sputtering process comprises exposing the shutter disk to a plasma.

6. The method of claim 5, wherein the shutter disk comprises one or more of titanium, barium, or cerium.

7. The method of claim 1, further comprising moving the shutter disk to a buffer station and positioning the substrate in the processing chamber.

8. The method of claim 1, wherein the outgassing molecules include one or more of oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), or water (H2O).

9. The method of claim 1, wherein the thickness of the gas getter material is greater than or equal to 10 nm.

10. The method of claim 1, wherein the plasma comprises one or more of argon (Ar) or helium (He).

11. The method of claim 1, wherein the substrate comprises one or more of aluminum (Al), copper (Cu), an oxide layer, or a polymer layer.

12. The method of claim 1, wherein the amount of CO outgassing from the substrate is reduced to less than or equal to 10% of CO outgassing from a substrate in a processing chamber without the getter material.

13. A processing tool comprising: a pre-clean chamber having a substrate support therein, the pre-clean chamber including a shutter disk including a getter material; buffer station; a robot configured to enter and exit the pre-cleaning chamber and the buffer station, and to move the shutter disk into and out of the pre-cleaning chamber and the buffer station; as well as a controller coupled to the pre-clean chamber, the buffer station, and the robot, the controller having a configuration for sputtering the shutter disk to deposit the getter material on a wall of a processing chamber and one or more configurations selected from the group consisting of etching a substrate using a plasma to remove native oxide and form a cleaned substrate, or depositing a barrier layer.

14. The processing tool of claim 13, wherein the buffer station is within the pre-clean chamber.

15. The processing tool of claim 13, wherein the buffer station is in a chamber adjacent to the pre-clean chamber.

16. The processing tool of claim 13, further comprising at least one slit valve for accessing the pre-clean chamber and the buffer station.

17. The processing tool of claim 13, wherein the controller comprises one or more of a central processing unit (CPU), memory, input / output (I / O), or support circuitry.

18. A non-transitory computer readable medium comprising a plurality of instructions that, when executed by a controller of a processing chamber, cause the processing chamber to: transferring a shutter disk to the processing chamber, the shutter disk comprising a gas getter material; sputtering the shutter disk to deposit a thickness of the getter material on a wall of the processing chamber; etching a substrate in the processing chamber using a plasma to remove native oxide and form a cleaned substrate, wherein etching the substrate releases outgassing molecules that chemically bond to the getter material; as well as The shutter disk is removed from the processing chamber.

19. The non-transitory computer readable medium of claim 18, wherein depositing a thickness of the getter material comprises exposing the shutter disk to a plasma.

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