Shutter disc

Abstract

To provide improved under bump metallization (UBM) methods for flip-chip and wafer level packaging.SOLUTION: A shutter disk incorporating getter materials 204 that are highly selective to reactive gas molecules, including O2, CO, CO2 and water, is disposed in a processing chamber 200 for pre-clean before UBM, the shutter disk comprising one or more of titanium (Ti), barium (Ba), or cerium (Ce), and the getter materials are pasted by physical vapor deposition (PVD) on a chamber wall. Thereafter, the shutter disk is transferred, a substrate 209 is positioned within the processing chamber 200, and the substrate 209 is etched, as pre-clean, with argon (Ar) or helium (He) plasma. Because the getter materials are able to absorb outgassing molecules, the concentration of outgassing molecules in the processing chamber 200 is significantly reduced, and, therefore, defects during an UBM process can be controlled.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to electronic devices, and more particularly to under bump metallization in wafer level or flip chip packages. [Background technology]

[0002] Throughout the evolution of semiconductor manufacturing, various packaging technologies have been implemented, with wafer-level manufacturing and flip-chip packaging technologies for electronic devices at the forefront of miniaturization solutions.

[0003] The goal of semiconductor packaging is to achieve shorter electronic paths for increased speed, reduced power, improved device functionality, and reduced cost. Underbump metallization (UBM) is required to connect the die to the substrate using solder bumps for flip-chip packaging. UBM for integrated circuits (ICs) bonds pads, which are typically aluminum or copper. This is an essential process step for the reliability of electronic packages.

[0004] Several options are available for achieving underbump metallization (UBM). Dry vacuum sputtering combined with electroplating is the most common method used, involving multiple metal layers 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. Aluminum is preferred for traditional wirebonding interconnects because wirebonding techniques form acceptable connections through the oxide layer typically present. Aluminum, however, is not solderable, fusible, or bondable to the bump and soldering materials used in reflow soldering. The UBM layer creates a good bond to the aluminum pad, encapsulating the aluminum and preventing potential metal diffusion into the IC package.

[0005] Aluminum oxidizes almost immediately when exposed to the environment, so the primary challenge in UBM processing is removing the native oxide layer from aluminum IC pads. Therefore, the UBM process requires a pre-clean step to remove the native oxide from the metal contact pads before deposition of the barrier layer. During the pre-clean process, however, outgassing molecules and species are generated, which can recontaminate the clean metal surface and cause high contact resistance, which can affect integrated circuit performance.

[0006] Therefore, there is a need for improved under-bump metallization methods for flip-chip and wafer-level packaging. Summary of the Invention

[0007] One or more embodiments of the present disclosure are directed to a processing method that includes depositing a getter material to a thickness on a wall of a processing chamber and etching the substrate with a plasma in the processing chamber to remove native oxide and form a cleaned substrate, where etching the substrate releases outgassing molecules chemically bonded to the getter material.

[0008] An additional embodiment of the present disclosure is directed to a processing tool including a pre-clean chamber having a substrate support therein, a buffer station, a robot configured to access the pre-clean chamber and the buffer station, and a controller connected to the pre-clean chamber, the buffer station, and the robot, the controller having one or more configurations selected from depositing a getter material, etching a substrate, or depositing a barrier layer.

[0009] A further embodiment of the present disclosure is directed to a non-transitory computer-readable medium including instructions that, when executed by a controller of a processing chamber, cause the processing chamber to perform operations of depositing a getter material on walls of the processing chamber and etching a substrate using a plasma in the processing chamber.

[0010] So that the above-recited features of the present disclosure may be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and are therefore not to be considered as limiting the scope of the present disclosure, as the present disclosure may admit of other equally effective embodiments. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a flow diagram of a processing method according to one or more embodiments. [Figure 2] FIG. 1 illustrates a processing chamber according to one or more embodiments. [Figure 3] FIG. 1 illustrates a processing chamber according to one or more embodiments. [Figure 4] FIG. 1 illustrates a processing chamber according to one or more embodiments. [Figure 5] FIG. 1 illustrates a processing tool, according to one or more embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0012] Before describing several example embodiments of the present disclosure, it is to be understood that the present disclosure is not limited to the details of construction or process steps set forth in the following description. The present disclosure is capable of other embodiments and of being practiced or carried out in various ways.

[0013] Many of the details, dimensions, angles, and other features shown in the figures are representative of particular embodiments only. Thus, other embodiments may have other details, components, dimensions, angles, and features without departing from the spirit or scope of the present disclosure. Furthermore, further embodiments of the present disclosure may be practiced without some of the details described below.

[0014] As used herein and in the appended claims, the term "substrate" refers to a surface or portion of a surface upon which a process acts. It will be understood by those skilled in the art that a reference to a substrate may also refer to only a portion of a substrate, unless the context clearly indicates otherwise. Furthermore, a reference to depositing on a substrate may refer to both a bare substrate and a substrate having one or more films or features deposited or formed thereon.

[0015] As used herein, "substrate" refers to any substrate or material surface formed on a substrate on which a film treatment is performed during a manufacturing process. For example, substrate surfaces on which treatment 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 materials, such as metals, metal nitrides, metal alloys, and other conductive materials, depending on the application. Substrates include, but are not limited to, semiconductor wafers. Substrates may be subjected to pretreatment processes to polish, etch, reduce, oxidize, hydroxylate, anneal, UV cure, electron beam cure, and / or bake the substrate surface. In addition to performing film treatments directly on the surface of the substrate itself, in the present disclosure, any of the disclosed film treatment steps may also be performed on an underlayer formed on the substrate, as disclosed in more detail below, and the term "substrate surface" shall include such underlayers where the context indicates. Thus, for example, if a film / layer or partial film / layer is being deposited on a substrate surface, the exposed surface of the newly deposited film / layer becomes the substrate surface.

[0016] As used herein and in the appended claims, the terms "reactive compound," "reactive gas," "reactive species," "precursor," "process gas," etc. are used interchangeably to mean a substance having species capable of reacting with a substrate surface or materials on a substrate surface in a surface reaction (e.g., chemisorption, oxidation, reduction). For example, a first "reactive gas" may simply adsorb onto the surface of the substrate and be available for further chemical reaction with a second reactive gas.

[0017] Extensive efforts have been devoted to reducing polymer outgassing during under bump metallization (UBM), including 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 pasting method helps absorb outgassing molecules. As used herein, the term "pasting" refers to sputtering of getter material such that the getter material adheres to the walls of the processing chamber, thereby forming a layer of the getter material on the walls.

[0018] In one or more embodiments, the concentration of outgassed molecules in the processing chamber may 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.

[0019]

[0006] Several embodiments of the present disclosure provide a shutter disk including one or more of titanium (Ti), barium (Ba), or cerium (Ce) for physical vapor deposition (PVD), which allows the pasting to minimize outgassing and control defects during etching of a substrate. One or more embodiments provide an improved and / or enhanced useful life of the process kit.

[0020] In one or more embodiments, pasting a getter material onto / in a processing chamber, such as a pre-clean chamber, has been observed to reduce the concentration of outgassed molecules by at least two orders of magnitude, with observed results superior to other methods, including increased pumping speed and improved gas conductance.

[0021] Several embodiments of the present disclosure incorporate getter materials that are highly selective for reactive gas molecules, such as oxygen (O), carbon monoxide (CO), carbon dioxide (CO), and water (HO). These reactive gas molecules can be detrimental to metal contact resistance in PVD-deposited devices. Some embodiments provide titanium (Ti), barium (Ba), or cerium (Ce) shutter disks that advantageously minimize shielding gas emissions, extend shield kit life, prevent recontamination of metal surfaces, act as getter materials, absorb outgassing molecules, including oxygen (O), carbon monoxide (CO), carbon dioxide (CO), and water (HO), during processing, can withstand high temperatures, and / or have minimal warping during processing.

[0022] Several 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 a processing chamber, and RF power is used to perform a sputtering process that sputters the getter material onto the sides of the processing chamber. In one or more embodiments, the shutter disk does not react with inert gas molecules such as argon (Ar) and helium (He), thus limiting the impact of inert gas molecules on the physical plasma sputtering effect in the pre-cleaning process.

[0023] Referring to FIGS. 1-4, one or more embodiments are directed to a method 100 for processing a substrate. The method illustrated in FIG. 1 represents a physical vapor deposition (PVD) process. As used herein, the terms "physical vapor deposition," or alternatively, "sputtering," refer to a process for depositing metals and related materials in the fabrication 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 vias or other vertical interconnect structures. Plasma sputtering can be achieved using either DC or RF sputtering. Plasma sputtering generally involves a magnetron located behind the sputtering target, which includes two magnets of opposite polarity magnetically coupled at their backs through a magnetic yoke to project a magnetic field into the processing space to increase the density of the plasma from the front of the target and improve the sputtering rate. The magnets used in the magnetron are generally closed-loop for DC sputtering and open-loop for RF sputtering.

[0024] In plasma-enhanced substrate processing systems, such as physical vapor deposition (PVD) chambers, high-power-density PVD sputtering using a strong magnetic field and high DC power can generate high energy at the sputtering target, causing a large increase in the sputtering target's surface temperature. The sputtering target is cooled by contacting a target backing plate with a cooling fluid. In typical commercial plasma sputtering, a target of the material to be sputter-deposited is sealed in a vacuum chamber containing the wafer to be coated. An inert gas, such as argon (Ar), is introduced into the chamber. When a negative DC bias of several hundred volts is applied to the target while the chamber walls or shield remain grounded, the inert gas is excited into a plasma. Positively charged inert gas ions are attracted to the highly energetic, negatively biased target and sputter target atoms from the target.

[0025] In one or more embodiments, in operation 10, getter material 204 is deposited on at least one wall of processing chamber 200. In one or more embodiments, getter material 204 is deposited on at least one wall of processing chamber 200 to a thickness 202. In one or more embodiments, thickness 202 is 10 nm or greater, including in the range of about 10 nm to about 100 μm. In one or more embodiments, getter material 206 includes one or more of titanium (Ti), barium (Ba), or cerium (Ce). In one or more embodiments, getter material 204 is obtained by sputtering shutter disk 206. In one or more embodiments, the sputtering process includes exposing shutter disk 206 to plasma 208. In one or more embodiments, plasma 208 includes an inert plasma. In some embodiments, plasma 208 includes one or more of argon (Ar) or helium (He).

[0026] 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 conductively coupled plasma (CCP). Any suitable power can be used, depending on, for example, the reactants and other process conditions. In some embodiments, the plasma 208 is generated using a plasma power in a range from about 10 W to about 3000 W. In some embodiments, the plasma 208 is generated using a plasma power of about 3000 W or less, about 2000 W or less, about 1000 W or less, about 500 W or less, or about 250 W or less.

[0027] In one or more embodiments, the shutter disk 206 includes one or more of titanium (Ti), barium (Ba), or cerium (Ce). In certain embodiments, the shutter disk 206 includes titanium (Ti) and, upon sputtering, releases the getter material 204 including titanium (Ti), such that the titanium is deposited on at least one wall of the processing chamber 200.

[0028] In one or more embodiments, in operation 20, the shutter disk 206 is then moved or transferred to a buffer station. 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, in operation 30, the substrate 209 is then placed into the processing chamber 200.

[0029] In one or more embodiments, the 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, the oxide layer 212 includes an aluminum oxide layer. In one or more embodiments, the metal layer 214 includes one or more of aluminum (Al) or copper (Cu). In one or more embodiments, the polymer layer 216 includes one or more of a polyimide or a polybenzoxazole.

[0030] In one or more embodiments, in operation 40, substrate 209 is etched in processing chamber 200. In one or more embodiments, substrate 209 is etched by plasma 208. In one or more embodiments, plasma 208 comprises an inert plasma. In some embodiments, plasma 208 comprises one or more of argon (Ar) or helium (He). In some embodiments, plasma 208 is the same as the plasma used to sputter getter material 204 onto at least one sidewall of the processing chamber. In other embodiments, plasma 208 is different from the plasma used to sputter getter material 204.

[0031] Without intending to be bound by theory, upon etching the polymer layer 216 of the substrate 209, the substrate 209 releases outgassing molecules, e.g., 220, 222, 224, 226. In one or more embodiments, the outgassing molecules are absorbed by the getter material 204 deposited on the sides of the processing chamber 200. In one or more embodiments, the outgassing molecules include one or more of oxygen (O), carbon monoxide (CO), carbon dioxide (CO), or water (H2O). As shown in FIG. 4 , because the getter material is capable of absorbing the outgassing molecules, the concentration of the outgassing molecules in the processing chamber is significantly reduced, thus minimizing recontamination to the metal contact surface 214 of the substrate 209 to maintain low contact resistance for better electronic device performance.

[0032] In one or more embodiments, the amount of outgassed molecules from the substrate 209 is reduced to about 10% or less of the outgassed molecules from a substrate in a processing chamber that does not include a getter material. In one or more specific embodiments, the amount of outgassed carbon monoxide (CO) from the substrate 209 is reduced to about 10% or less of the outgassed carbon monoxide (CO) from a substrate in a processing chamber that does not include a getter material.

[0033] 5 illustrates a processing tool 300 according to one or more embodiments of the present disclosure. The embodiment illustrated in FIG. 5 represents only one possible configuration and should not be taken as limiting the scope of the present disclosure. For example, in some embodiments, the processing tool 300 has a different number of one or more of the processing chambers 302, buffer stations 310, and / or robot 308 configurations than the illustrated embodiment.

[0034] The exemplary processing tool 300 includes a multi-sided processing chamber 302, such as a pre-clean chamber. The illustrated processing chamber 302 has a first side 303a, a second side 303b, a third side 303c, and a fourth side 303d. While four sides are shown, one skilled in the art will understand that there can be any suitable number of sides for the processing chamber 302, depending, for example, on 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.

[0035] A robot 308 is disposed within the processing chamber 302. The robot 308 can be any suitable robot capable of moving a wafer during processing. In some embodiments, the robot 308 has a first arm 309a and a second arm 309b. The first arm 309a and the second arm 309b can move independently of the other arm. The first arm 309a and the second arm 309b can move in the x-y plane and / or along the z-axis. In some embodiments, the robot 308 includes a third arm (not shown) or a fourth arm (not shown). Each arm can move independently of the other arm.

[0036] The processing tool 300 may also include one or more buffer stations 310 connected to the first side 303 a 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 to be processed and returned to the original cassette, or one of the buffer stations may hold unprocessed wafers to be moved to the other buffer station after processing. In some embodiments, one or more of the buffer stations are configured to pre-process, pre-heat, or clean wafers before and / or after processing.

[0037] The processing tool 300 may also include one or more slit valves 312 between the processing chambers 302 and the buffer station 310. The slit valves 312 can be opened and closed to isolate the internal volume within the processing chambers 302. For example, if the processing chamber 302 generates plasma during processing, it may be useful to close the slit valve for that processing chamber to prevent stray plasma from damaging the robot in the transfer station.

[0038] 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 shutter disks into and out of the processing chamber 302 to the buffer station 310.

[0039] A controller 314 may be provided and coupled to various components of the processing tool 300 to control the operation of the processing tool 300. 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 chambers 302, the buffer station 310, and the robot 308.

[0040] In some embodiments, the processing chamber 302 further comprises a controller 314 connected to the plurality of substantially coplanar support surfaces 304. In one or more embodiments, the controller 314 controls the rate of movement of the substrate support assembly 304.

[0041] In some embodiments, the controller 314 includes a central processing unit (CPU) 316, memory 318, input / output (I / O) 320, and support circuits 322. The controller 314 may control the processing tool 300 directly or through computers (or controllers) associated with particular process chambers and / or support system components.

[0042] The controller 314 may be one of any form of general-purpose computer processor that may be used in an industrial environment to control various chambers and sub-processors. The memory 318, or computer-readable medium of the controller 314, may be one or more of readily available memory, such as local or remote random access memory (RAM), read-only memory (ROM), floppy disk, hard disk, optical storage medium (e.g., compact disk or digital video disk), flash drive, or any other form of digital storage. The memory 318 may hold a set of instructions operable by the processor (CPU 316) to control parameters and components of the processing tool 300.

[0043] The support circuits 322 are coupled to the CPU 316 for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input / output circuits and subsystems, etc. One or more processes may be stored in the memory 318 as software routines that, when executed or called by the processor, cause the processor to control the operation of the processing tool 300 or individual processing chambers in the manner described herein. The software routines may also be stored and / or executed by a second CPU (not shown) located remotely from the hardware controlled by the CPU 316.

[0044] 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 using a computer system in hardware, for example, as an application-specific integrated circuit or other type of hardware implementation, or implemented and executed as a combination of software and hardware. The software routines, when executed by a processor, transform a general-purpose computer into a special-purpose computer (controller) that controls chamber operation so that the processes are performed.

[0045] In some embodiments, the controller 314 has one or more configurations for executing individual processes or subprocesses to perform the method. The controller 314 may be connected to and configured to operate intermediate components to perform the functions of the method. For example, the controller 314 may be connected to and configured to control one or more of gas valves, actuators, motors, slit valves, vacuum controls, or other components.

[0046] 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 that embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of phrases such as "in one or more embodiments," "in certain embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the present disclosure. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0047] Although the disclosure herein has been described with reference to particular embodiments, those skilled in the art will recognize that the described 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 can be made to the disclosed method and apparatus without departing from the spirit and scope of the present disclosure. Accordingly, the present disclosure may include modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. A processing method comprising: transferring the shutter disk containing the getter material to a processing chamber; sputtering the shutter disk to deposit a thickness of the getter material on the walls of a processing chamber; etching the substrate with a plasma in the processing chamber to remove native oxide and form a cleaned substrate, thereby releasing outgassing molecules chemically bonded to the getter material; A processing method comprising:

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 getter material comprises one or more of titanium, barium, or cerium.

5. The method of claim 1 , wherein the sputtering comprises exposing the shutter disk to a plasma.

6. The method of claim 5 , wherein the shutter disc 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 placing the substrate in the processing chamber.

8. The gas-releasing molecules are oxygen (O ２ ), carbon monoxide (CO), carbon dioxide (CO ２ ), or water (H ２ 0). The method of claim 1 , comprising one or more of:

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

13. a pre-clean chamber having a substrate support therein and including a shutter disk including a getter material; a buffer station; a robot configured to access the pre-clean chamber and the buffer station and to move the shutter discs into and out of the pre-clean chamber and the buffer station; a controller connected to the pre-clean chamber, the buffer station, and the robot, the controller having configuration for sputtering the shutter disk to deposit the getter material on a wall of a process chamber, and configuration for etching a substrate with a plasma in the process chamber to remove native oxide and form a cleaned substrate, wherein etching the substrate releases outgassing molecules chemically bonded to the getter material; and A processing tool comprising:

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 circuits.

18. The processing tool of claim 13 , wherein the getter material comprises one or more of titanium, barium, or cerium.

19. The processing tool of claim 13 , wherein the plasma comprises one or more of argon (Ar) or helium (He).

20. The processing tool of claim 13 , wherein the substrate comprises one or more of aluminum (Al), copper (Cu), an oxide layer, or a polymer layer.

21. The method of claim 1, further comprising removing the shutter disk from the processing chamber.

22. The processing tool of claim 13, further comprising a configuration for depositing a barrier layer onto the cleaned substrate.

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