Apparatus and method of forming an indium gallium zinc oxide layer

The embodiments of the disclosure may generally provide a method and apparatus for forming thin film transistor device that includes an indium gallium zinc oxide (IGZO) layer using a multi-component precursor gas. The embodiments of the disclosure may provide a plasma enhanced chemical vapor deposition system configured to form an IGZO layer on large area substrates. However, it should be understood that the disclosure has utility in other system configurations such other types of chemical vapor deposition systems and any other system in which distributing a multi-component precursor gas to and within a process chamber is desired.

BACKGROUND OF THE DISCLOSURE

Embodiments of the disclosure generally relate to a method and apparatus for forming a thin-film transistor device.

2. Description of the Background Art

Several trends in the evolution of flat screen displays are driving research and development efforts to improve the display performance or display manufacturability, such as larger screen sizes, smaller pixel sizes, LED-based pixels and reduced power consumption of the display. The latter three of these relate to thin film transistors (TFTs) which control the pixels within a display. Because indium gallium zinc oxide (IGZO) films can be made with a carrier mobility 20-50 times greater than that of amorphous silicon, TFTs that have IGZO channels can result in display devices, which are smaller, transparent and have reduced power consumption characteristics as compared to devices that contain an amorphous silicon containing channel layer.

A flat screen display typically contains a rectangular array of pixels, where the pixel is either a light switch (e.g., LCD) or a light source (e.g., OLED). In either case, most displays utilize one transistor for switching or controlling each pixel.

TFTs are a type of field effect transistor (FET). TFTs can be formed by depositing and lithographically patterning a series of layers that are formed over a substrate, such as a glass substrate. Semiconducting thin film materials, such as amorphous silicon or a metal-oxide semiconductor, typically form at least part of the semiconducting channel region of a TFT device, that is formed between a source and a drain. A gate is located in proximity to the channel, so that when a voltage is applied to the gate it can produce an electric field that affects the ability of carriers to move between the source and drain regions. By applying a voltage to a gate, a source-drain current can be turned on or turned off, thus forming a switch or an amplifier.

IGZO thin films have been deposited using methods, such as physical vapor deposition (PVD), atomic layer deposition (ALD), and chemical vapor deposition (CVD) processes. The other layers deposited in the manufacturing of a display TFT, such as metals, dielectrics or electrically insulating layers, may also utilize these deposition methods.

Due to the electrical and mechanical properties of an IGZO layer, process development efforts have shown that IGZO layers can help to reduce the pixel size, reduced TFT power consumption, and even form high resolution OLED products. However, the formation of an IGZO layer has its own set of challenges. First of all, PVD IGZO films are limited to stoichiometries of the formed PVD target material, which typically have a composition of either 5:1:1 or 1:1:1 (indium:gallium:zinc ratios), where the oxygen component of the IGZO film is introduced through reactive sputtering or a post-deposition treatment. This not only limits PVD IGZO process development, but limits a PVD deposited IGZO containing structure to a single layer having either a 5:1:1 composition or a 1:1:1 composition, or to a bi-layer structure, where one film has 5:1:1 composition and the other has a 1:1:1 composition. Finally, a PVD bi-layer process requires two separate PVD chambers, which is more expensive in production than a single-chamber process. In this disclosure, the words “layer” and “film” are used interchangeably; and the term “sublayer” is meant to denote a part of a layer.

Another problem with IGZO films is their susceptibility to environmental degradation, reported as the diffusion of hydrogen atoms into the IGZO active layer which affects transistor properties. Moving substrates between processing systems introduces exposure to atmospheric humidity, which can be absorbed into substrates and the deposited films. Native oxides can also form on materials exposed to air.

Therefore, there is a need for a method and apparatus for forming thin film transistor device that includes an indium gallium zinc oxide (IGZO) layer that solves the problems described above.

SUMMARY

Embodiments of the disclosure provided herein may provide a system for forming a multi-element containing film, comprising a gas distribution plate assembly comprising a first precursor plenum, a second precursor plenum and a heat exchanging channel formed in a body of the gas distribution plate assembly, a plurality of first gas conduits extending from the first precursor plenum through the heat exchanging channel, wherein each of the plurality of first gas conduits are in fluid communication with the first plenum and a processing region of a processing chamber, a plurality of second gas conduits extending from the second precursor plenum through the heat exchanging channel and the first precursor plenum, wherein each of the plurality of second gas conduits are in fluid communication with the second plenum and the processing region, an exhaust line that is disposed between and is in fluid communication with an exhaust pump and the processing region, a precursor line assembly that is in fluid communication with the first precursor plenum or the second precursor plenum, a vent line assembly that is in fluid communication with the exhaust line, and a plurality of precursor delivery systems. The precursor delivery systems each may comprise an ampoule having an inlet and an outlet, wherein an inner volume of the ampoule is configured to receive a precursor material and is in fluid communication with the inlet and the outlet, a vapor delivering source assembly that is configured to deliver a first gas to the inlet and inner volume of the ampoule, and a back pressure regulator that has an upstream side that is in fluid communication with the outlet of the ampoule and a downstream side that is fluid communication with either the precursor line assembly or the vent line assembly.

Embodiments of the disclosure may further provide a method of forming a multi-element containing film, comprising flowing a first multi-component precursor gas through a first plenum of a gas distribution plate assembly and into a processing region of a process chamber for a first period of time and a second period of time, wherein the first plenum is fluidly coupled to the processing region through a plurality of first gas conduits, and the first multi-component precursor gas is formed by mixing a first precursor gas and a second precursor gas in the first plenum or a precursor delivery line that is coupled to the first plenum, flowing a second multi-component precursor gas into a vent line assembly for a third period of time, wherein the second multi-component precursor gas is formed by mixing the first precursor gas and the second precursor gas, and the vent line assembly is fluidly coupled to an exhaust line that is disposed between and in fluid communication with the processing region and an exhaust pump, and introducing a heat exchanging fluid to a heat exchanging channel, wherein the plurality of first gas conduits extend through the heat exchanging channel, wherein flowing a second multi-component precursor gas into a vent line assembly for the third period of time is performed after flowing the first multi-component precursor gas through the first plenum for the first period of time and before flowing the first multi-component precursor gas through the first plenum for the second period of time.

DETAILED DESCRIPTION

The embodiments of the disclosure may provide a method and apparatus for forming a thin film transistor (TFT) device that includes an indium gallium zinc oxide (IGZO) layer. The embodiments of the disclosure are illustratively described below in reference to a plasma enhanced chemical vapor deposition system configured to form an IGZO layer on large area substrates, such as a plasma enhanced chemical vapor deposition (PECVD) system, available from AKT, a division of Applied Materials, Inc., Santa Clara, Calif. However, it should be understood that the embodiments disclosed herein have utility in other system configurations, such as other types of chemical vapor deposition systems and other systems that are configured to distribute a multi-component precursor gas to and within a process chamber, including those systems configured to process round substrates.

FIG. 1illustrates cross-sectional schematic views of a thin film transistor structure100. The substrate101may comprise a material that is essentially optically transparent in the visible spectrum, such as, for example, glass or clear plastic. The substrate may be of varying shapes or dimensions. Typically, for TFT applications, the substrate is a glass substrate with a surface area greater than about 500 mm2. A gate electrode layer102is formed on the substrate101. The gate electrode layer102comprises an electrically conductive layer that controls the movement of charge carriers within the TFT. The gate electrode layer102may comprise a metal such as, for example, aluminum (Al), tungsten (W), chromium (Cr), tantalum (Ta), or combinations thereof, among others. The gate electrode layer102may be formed using conventional deposition, lithography and etching techniques. Between the substrate101and the gate electrode layer102, there may be an optional insulating material, for example, such as silicon dioxide (SiO2) or silicon nitride (SiN), which may also be formed using an embodiment of a PECVD system described in this disclosure. The gate electrode layer102is then lithographically patterned and etched using conventional techniques to define the gate electrode.

A gate dielectric layer103is formed on the gate electrode layer102. The gate dielectric layer103may be silicon dioxide (SiO2), silicon oxynitride (SiON), or silicon nitride (SiN), deposited using an embodiment of a PECVD system described in herein. The gate dielectric layer103may be formed to a thickness in the range of about 100 Å to about 6000 Å. In some cases, the gate dielectric layer103can be formed using a high density plasma (HDP) type of PECVD (plasma enhanced chemical vapor deposition) process chamber, such as those manufactured and sold by Applied Materials for manufacturing TFT's on rectangular display substrates. The gate dielectric layer103may be formed by delivering a silicon containing precursor gas (e.g., silane, disilane) to a processing region of a process chamber to form a silicon containing layer on the surface of the substrate. The process chamber may be similar to, for example, process chamber210(FIG. 2) and/or process chamber300inFIG. 3, which are discussed below.

A bulk semiconductor layer104is formed on the gate dielectric layer103. The bulk semiconductor layer104may comprise an IGZO active layer, which could be deposited using an embodiment of a PECVD system described herein. The bulk semiconductor layer104may be deposited to a thickness in the range of about 100 Å to about 3000 Å. The IGZO active layer may in some cases include three separate sub-layers104A,104B, and104C. In one example, the stoichiometric properties of sub-layer104A are tailored for optimizing gate dielectric interface-related electrical properties. In another simpler embodiment, the bulk semiconductor layer104includes only one sub-layer. In some embodiments, the bulk semiconductor layer104is composed of N sub-layers for optimizing TFT electrical performance. In yet another embodiment, bulk semiconductor layer104is composed of a large number N, such that individual sublayers are physically indistinguishable, but the resulting layer contains an observable gradient in material composition and/or properties. The bulk semiconductor layer104may also be a simple single layer that can be produced in a CVD process chamber by controlling gas flows and other process parameters as a function of time. An example of the process chamber is described below, and may be available from Applied Materials' AKT division.

A doped semiconductor layer105is formed on top of the bulk semiconductor layer104. The doped semiconductor layer105may comprise an n-type (n+) or p-type (p+) doped IGZO layer, an IGZO layer with a different composition than the bulk semiconductor layer104, a polycrystalline (polysilicon) or an amorphous silicon (α-Si), which could be deposited using an embodiment of a PECVD system described in this disclosure or other conventional methods known to the art. Doped semiconductor layer105may be deposited to a thickness within a range of about 100 Å to about 3000 Å. The bulk semiconductor layer104and the doped semiconductor layer105are lithographically patterned and etched using conventional techniques to define a mesa of these two films over the gate dielectric insulator, which also serves as storage capacitor dielectric. The doped semiconductor layer105directly contacts portions of the bulk semiconductor layer104, forming a semiconductor junction.

A conductive layer106is then deposited on the exposed surface. The conductive layer106may comprise a metal such as, for example, aluminum (Al), tungsten (W), molybdenum (Mo), chromium (Cr), tantalum (Ta), and combinations thereof, among others. The conductive layer106may be formed using conventional deposition techniques. Both the conductive layer106and the doped semiconductor layer105may be lithographically patterned to define source and drain contacts of the TFT. Afterwards, a passivation layer107may be deposited. Passivation layer107may conformally coat the exposed surfaces and features, such as feature109. The passivation layer107is generally an insulator and may comprise, for example, silicon dioxide (SiO2) or silicon nitride (SiN). The passivation layer107may be formed using, for example, PECVD or other conventional methods known to the art. The passivation layer107may be deposited to a thickness in the range of about 1000 Å to about 5000 Å. The passivation layer107is then lithographically patterned and etched using conventional techniques to open contact holes in the passivation layer107.

A transparent conductor layer108is then deposited and patterned to make contacts with the conductive layer106. The transparent conductor layer108comprises a material that is essentially optically transparent in the visible spectrum and is electrically conductive. Transparent conductor layer108may comprise, for example, indium tin oxide (ITO) or zinc oxide, among others. Patterning of the transparent conductor layer108is accomplished by conventional lithographical and etching techniques.

Processing System Components

FIG. 2is a top plan view of a substrate processing system200suitable for forming one or more of the layers of the thin film transistor structure100discussed above using one or more of the various deposition techniques described herein on a substrate222. The substrate processing system200typically includes a transfer chamber208coupled to a factory interface202via a load lock chamber204and a plurality of the process chambers210,212,214,216,218that are adapted to process the substrate222.

The factory interface202generally includes one or more substrates stored therein or substrate storage cassettes. The substrate storage cassettes are typically removably disposed in a plurality of storage bays/compartment formed inside the factory interface202. The factory interface202may also include an atmospheric robot, such as a dual blade atmospheric robot. The atmospheric robot is adapted to transfer one or more substrates between the one or more substrate storage cassettes and the load lock chamber204. Typically, the factory interface202is maintained at or slightly above atmospheric pressure and the load lock chamber204is disposed to facilitate substrate transfer between a vacuum environment of the transfer chamber208and a generally ambient environment of the factory interface202.

In one embodiment, the substrate processing system200is adapted to include various types of process chambers that are coupled to the transfer chamber208. For example, the substrate processing system200may include one or more CVD chambers, PVD chambers, atomic layer deposition (ALD), preclean chambers, thermal processing chambers, substrate inspection chambers, or other useful process chambers.

The transfer chamber208is generally adapted to provide an environment in which substrates can be transferred between a plurality of process chambers210,212,214,216,218and one or more load lock chambers204. The transfer chamber208is maintained at a vacuum condition to eliminate or minimize pressure differences between the transfer chamber208and the individual process chambers210,212,214,216,218after each substrate transfer. A transfer robot230, such as a dual arm vacuum robot available from Applied Materials, Inc., can be coupled to and/or within the transfer chamber208for moving the substrate222. Accordingly, the first transfer robot230is configured to be rotatably movable within the transfer chamber208. In one configuration, the substrate222can be transferred within the substrate processing system200among one or more process chambers210,212,214,216,218, and at least one of the process chambers is a PECVD chamber, such as described below in conjunction withFIG. 3A.

As shown inFIG. 2, the substrate222processed by the substrate processing system200can flow from the factory interface202to the load lock chamber204during a substrate fabrication sequence performed in the processing system200. Further, the substrate222processed within the processing system200can be delivered through the various process chambers210,212,214,216,218during the substrate fabrication sequence, such as described herein. In one example, the substrate222is first processed within process chamber210and then processed within process chamber212during the substrate fabrication sequence, wherein the process(es) performed in the process chamber210include the formation of a silicon dioxide (SiO2), silicon oxynitride (SiON), or silicon nitride (SiN) layer, and process performed in the process chamber220includes the formation of an IGZO layer on the substrate222. The load lock chambers204may be a used as a buffer station for providing the substrate222, which may allow the timely and sequential delivery of the substrates during one or more parts of the integrated substrate fabrication sequence. Preferably, the system includes a plurality of vacuum sealable valves that are used in various parts of the substrate processing system200, such as slit valves, gate valves, slot valves, etc. For example, the first load lock chamber may include internal or external vacuum sealable valves for maintaining a low pressure level after the substrate is loaded into and from the atmospheric environment of the factory interface202. In addition, the valves may be coupled to an internal or external actuator for opening and closing. In addition, the use of different types of pumps, such as a dry pump, a roughing pump, a turbo pump, and a cryogenic pump, among others, can be used to provide desirable vacuum pressure levels or staged vacuum levels as needed within one or more parts of the processing system200.

In some configurations of the substrate processing system200, a system controller290may be used to control one or more components found in the processing system200. The system controller290is generally designed to facilitate the control and automation of the processing system200and typically includes a central processing unit (CPU)292, memory294, and support circuits (or I/O)296. The CPU may be one of any form of computer processors that are used in industrial settings for controlling various system functions, substrate movement, chamber processes, and control support hardware (e.g., sensors, robots, motors, lamps, etc.), and monitor the processes performed in the system (e.g., substrate support temperature, power supply variables, chamber process time, I/O signals, etc.). The memory294is connected to the CPU292, and may be one or more of a readily available memory, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. Software instructions and data can be coded and stored within the memory for instructing the CPU. The support circuits are also connected to the CPU for supporting the processor in a conventional manner. The support circuits may include cache, power supplies, clock circuits, input/output circuitry, subsystems, and the like. A program (or computer instructions) readable by the system controller290determines which tasks are performable on a substrate in one or more of the process chambers210,212,214,216,218and in the processing system200. Preferably, the program is software readable by the system controller290that includes code to perform tasks relating to monitoring, execution and control of the movement, support, and/or positioning of a substrate along with the various process recipe tasks and various chamber process recipe steps being performed in the processing system200.

FIG. 3Ais a schematic cross-sectional view of one embodiment of a process chamber300, such as a plasma enhanced chemical vapor deposition chamber that is available from Applied Materials, Inc. of Santa Clara, Calif. In one configuration, the process chamber300may be one of the one or more process chambers210,212,214,216,218disposed in the processing system200, which is described above. The process chamber300generally includes a processing chamber body302coupled to a plurality of gas sources, such as gas source assembly304and gas source assembly305. The processing chamber body302has walls306and a bottom308that partially define a processing region312. The processing region312is typically accessed through a port (not shown) in the walls306that facilitate movement of a substrate340into and out of the processing chamber body302. The walls306and bottom308are typically fabricated from a unitary block of aluminum or other material that is compatible with the processing environment. The walls306support a lid assembly310that contains a pumping plenum314that couples the processing region312to an exhaust line307A that is coupled to an exhaust pump307, which includes various vacuum generating pumping components (not shown). The exhaust pump307may include one or more types of pumps, such as a dry pump, a roughing pump, a turbo pump or a cryogenic pump that can be used to provide a desirable vacuum pressure level in the processing region312of the process chamber300.

A temperature controlled substrate support assembly338is centrally disposed within the processing chamber body302. The support assembly338supports a substrate340during processing. In one embodiment, the substrate support assembly338comprises an aluminum body that encapsulates at least one embedded heater332. The heater332(e.g., resistive element) is disposed in the support assembly338and is coupled to an optional power source374. The heater332and optional power source374can be used in combination to controllably heat the support assembly338and the substrate340positioned thereon to a predetermined temperature. Typically, in a CVD process, the heater332maintains the substrate340at a uniform temperature between about 150 to at least about 460 degrees Celsius, depending on the deposition processing parameters for the material being deposited.

Generally, the support assembly338has a lower side326and an upper side334. The upper side334supports the substrate340. The lower side326has a stem342coupled thereto. The stem342couples the support assembly338to a lift system (not shown) that moves the support assembly338between an elevated processing position (as shown) and a lowered position that facilitates substrate transfer to and from the processing chamber body302. The stem342additionally provides a conduit for electrical and thermocouple leads between the support assembly338and other components of the chamber300.

A bellows346is coupled between support assembly338(or the stem342) and the bottom308of the processing chamber body302. The bellows346provides a vacuum seal between the processing region312and the atmosphere outside the processing chamber body302while facilitating vertical movement of the support assembly338.

The support assembly338is typically grounded, such that RF power supplied by a power source322to a gas distribution plate assembly318positioned between the lid assembly310and substrate support assembly338(or other electrode positioned within or near the lid assembly310of the chamber) may excite gases present in the processing region312between the support assembly338and the distribution plate assembly318. The RF power from the power source322is generally selected commensurate with the size of the substrate to drive the chemical vapor deposition process.

The support assembly338additionally supports a circumscribing shadow frame348. Generally, the shadow frame348prevents deposition at the edge of the substrate340and support assembly338so that the substrate does not stick to the support assembly338. The support assembly338has a plurality of holes328disposed therethrough that accept a plurality of lift pins350. The lift pins350are typically comprised of ceramic or anodized aluminum. The lift pins350may be actuated relative to the support assembly338by an optional lift plate354to project from the support surface330, thereby placing the substrate in a spaced-apart relation to the support assembly338.

The lid assembly310provides an upper boundary to the processing region312. The lid assembly310typically can be removed or opened to service the processing chamber body302. In one embodiment, the lid assembly310is fabricated from aluminum (Al). In some configurations, the pumping plenum314, which is formed in the lid assembly310, is utilized to channel gases and processing by-products uniformly from the processing region312and out of the processing chamber body302.

The gas distribution plate assembly318is coupled to an interior side320of the lid assembly310. The edge of the gas distribution plate assembly318is typically configured to substantially follow the profile of the substrate340, for example, polygonal for large area flat panel substrates and circular for wafers. The gas distribution plate assembly318includes a perforated area316through which process and other gases supplied from the gas source assembly304and/or305are delivered to the processing region312. The perforated area316of the gas distribution plate assembly318is configured to generally provide a uniform distribution of gases that pass through the gas distribution plate assembly318and into the processing chamber body302.

The gas distribution plate assembly318also typically includes a plurality of gas plenums, such as precursor plenum319A and precursor plenum319B, and a heat exchanging channel319C that are formed within the body318A of the gas distribution plate assembly318. The precursor plenum319A and precursor plenum319B are each in fluid communication with the processing region312by use of a plurality of gas distribution conduits, such as gas conduits323and324. In some configurations, the gas conduits323and324include a plurality of tubes or similar structures that are adapted to separately deliver the gases flowing through each of the precursor plenums319A,319B to the processing region312.

The gas source assemblies304and305are generally separately coupled to the gas the precursor plenums319A and319B, respectively, to provide one or more gases to the processing region312during processing. The gas source assemblies304and305may each include multiple sources that are adapted to deliver different types of gases to the processing region312. The gas source assemblies304and305are each coupled to inlet lines304A and305A, respectively, and are, for example, adapted to deliver a precursor gas and a carrier gas through the inlet lines304A and305A into the processing region312. Each inlet line304A and305A may comprise a plurality of separate gas lines that are in fluid communication with the precursor plenum319A and precursor plenum319B, respectively. Depending on the process(es) being run in the chamber300, some of the gas source assemblies304and305may include a vapor generation source that is used to form a precursor gas that is used to form a layer on a surface of the substrate disposed in the processing region312. The vapor may then be mixed with a carrier gas such as hydrogen (H2), nitrogen (N2), helium (He) and/or argon (Ar) prior to delivery to the process chamber300, which is further discussed below. Furthermore, the inlet lines304A and305A may include shut-off valves, mass flow controllers or other types of fluid controlling devices that can monitor, regulate and/or shut off the flow of gas in each line. While not intending to be limiting as to the scope of the disclosure described herein, in some configurations, the gas source assembly304is configured to deliver a multi-component precursor gas, as discussed further below, and the gas source assembly305is configured to provide a second precursor gas. In one example, the gas source assembly305is configured to provide a second precursor gas that comprises an oxygen containing gas, such as ozone gas (O3), oxygen (O2), oxygen containing radicals, oxygen containing ions or other similar gases that may be delivered from a gas source or generated by a remote plasma source (RPS), a UV source or other useful device. An example of gas flow schematic is illustrated inFIG. 4, which is discussed in more detail below.

Therefore, during operation a first process gas may flow through inlet line304A, from the gas source assembly304, into the precursor plenum319A and then into gas conduits323and then into the processing region312. Separately, a second process gas may flow from the gas source assembly305through the inlet line305A into the precursor plenum319B and then into gas conduits324and then into the processing region312. The precursor plenum319A is generally not in fluid communication with the precursor plenum319B, so that the first process gas and the second process gas remain isolated until they are injected into the processing region312located within the processing chamber body302. The first process gas and/or second process gas may comprise one or more precursor gases or other process gases, including carrier gases and dopant gases, to carry out desired processes within the processing region312. For example, the first process gas and second process gas may contain one or more precursors for deposition of a material on substrates340positioned on the support assembly338.

FIG. 3Bis a bottom view of the perforated area316of the surface317of the gas distribution plate assembly318, according to one embodiment of the disclosure provided herein.FIG. 3Cis a close-up bottom view of a portion of the perforated area316, according to one embodiment of the disclosure provided herein. In one configuration, as shown inFIGS. 3B and 3C, gas conduits323and324are formed in an interleaved pattern so that the precursor gases provided through the gas conduits323and the precursor gases provided through the gas conduits324are uniformly mixed and uniformly delivered from the perforated area316to the surface340A of the substrate340. In one example, the gas conduits323and324are formed in a square or rectangular pattern across the perforated area316. The components within the body318A of the gas distribution plate assembly318are typically fabricated from stainless steel, aluminum (Al), anodized aluminum, nickel (Ni) or other RF conductive material. The body318A of the gas distribution plate assembly318may be formed by casting, brazing, forging, welding, machining, hot iso-statically pressing and/or sintering plates, sheet, tubes and/or other useful material to form the complete structure. The gas distribution plate assembly318generally has a thickness that maintains a sufficient flatness so as not to adversely affect the processes performed within the process chamber300. The gas distribution plate assembly318could be circular for semiconductor wafer manufacturing or polygonal, such as rectangular, for flat panel display manufacturing.

The heat exchanging channel319C is coupled to a heat exchanging system309to control the temperature of the various surfaces of the gas distribution plate assembly318. The heat exchanging system309comprises a heat exchanger309A that is coupled to the one or more heat exchanging channels319C formed in the gas distribution plate assembly318via an inlet conduit309B and an outlet conduit309C. The heat exchanging channel319C through which a heat exchanging fluid flows is used to help regulate the temperature of the gas distribution plate assembly318.

The heat exchanging channel319C is disposed between the precursor plenum319B and the surface317of the gas distribution plate assembly318. The heat exchanging channel319C encircles the gas conduits323and324. Thus, the heat exchanging fluid can flow around and cool the gas or vapor flowing through the gas conduits323,324while the vapor flows into processing region312.

The positioning of a heat exchanging channel319C within the gas distribution plate assembly318provides control of the temperature of various showerhead assembly components or features, such as the gas conduits323and324and the showerhead face (e.g., surface317). Control of the temperature of the showerhead assembly is desirable to reduce or eliminate the formation of condensates on the gas distribution plate assembly318and help control the temperature of the substrate during processing. Control of the temperature of the various components in the showerhead assembly is also desirable to reduce gas phase particle formation and to prevent the production of undesirable precursor reactant products, which may adversely affect the composition of the film deposited on the substrates340. The showerhead temperature may be measured by one or more thermocouples (not shown) or other temperature sensors (not shown) disposed in proximity to the showerhead face, heat exchanging channel319C, and/or wall306. Additionally or alternatively, one or more thermocouples or other temperature sensors may be disposed in proximity to the inlet conduit309B and/or the outlet conduit309C. The temperature data measured by the one or more thermocouples or other temperature sensors is sent to the system controller290which may adjust the heat exchanging fluid temperature and flow rate to maintain the showerhead temperature within a predetermined range. The showerhead temperature is generally maintained at about 50 degrees Celsius to about 350 degrees Celsius, but may also be maintained at a temperature of greater than 350 degrees Celsius, if desired.

FIG. 3Dis a cross-sectional view of a portion of the gas distribution plate assembly318that is cut along a section line3D-3D (seeFIG. 3A), which extends through the heat exchanging channel319C. In some embodiments, as shown inFIG. 3D, the gas distribution plate assembly318is square or rectangular shaped, and the inlet conduit309B and outlet conduit309C are positioned at opposing corners of the gas distribution plate assembly318to assure that the fluid motion or movement through the heat exchanging channels319C is uniformly distributed. In this configuration, the heat exchanger309A is configured to deliver a cooled heat exchanging fluid through the inlet conduit309B formed in the gas distribution plate assembly318and into a conduit385formed in the heat exchanging channel319C, as shown by the flow381. The flow381of the cooled heat exchanging fluid is then delivered into the central region379of the heat exchanging channel319C. The flow of heat exchanging fluid then flows within a space that surrounds the gas conduits323and324, which are disposed in the central region379, as shown by the flow383. The heat exchanging fluid then flows from the central region379, through the outlet conduit386and then into the outlet conduit309C and then back to the heat exchanger309A, as illustrated by the flows383,384and387.

The flow rate of the heat exchanging fluid may be adjusted to help control the temperature of the gas distribution plate assembly318. Additionally, the thickness of the walls surrounding the heat exchanging channel319C may be designed to facilitate temperature regulation of various showerhead surfaces. Suitable heat exchanging fluids include water, water-based ethylene glycol mixtures, a perfluoropolyether (e.g., GALDEN® fluid), oil-based thermal transfer fluids, or liquid metals such as gallium or gallium alloy. The heat exchanging fluid can be maintained at a temperature of 20 degrees Celsius or greater, depending on process requirements. For example, the heat exchanging fluid can be maintained at a temperature within a range from about 20 degrees Celsius to about 120 degrees, or within a range of about 100 degrees Celsius to about 350 degrees Celsius. The heat exchanging fluid may also be heated above its boiling point so that the gas distribution plate assembly318may be maintained at higher temperatures using readily available heat exchanging fluids.

The lid assembly310typically also includes a cleaning source382that may provide a cleaning agent, or cleaning gas, such as dissociated halogen gas (e.g., chlorine (Cl2)), that is introduced into the processing chamber body302to remove deposition by-products and films from process chamber hardware, including the gas distribution plate assembly318. In some embodiments, the processing sequence performed in the processing chamber includes delivering a cleaning gas to the processing region312of the process chamber during a chamber idle or chamber maintenance period to clean one or more components disposed therein. In some cases, the cleaning gas is delivered to the processing region312through the precursor plenum319A and/or the precursor plenum319B from the cleaning source382. In some configurations, the cleaning source382includes a remote plasma source that is configured to excite the cleaning gas to form ions or radicals that are used to promote the activity of the cleaning gas during the cleaning process. In one example, the cleaning source382is configured to provide a cleaning gas that comprises a halogen containing gas, such as chlorine (Cl2), fluorine (F2), bromine (Br2), Iodine (I2), other gas containing one of these elements, or other similar gas that may be delivered from a gas source in the cleaning source382or gas radicals generated by a remote plasma source (RPS), a UV source or other useful device. In one example, the cleaning process includes generating a plasma containing a cleaning gas that comprises chlorine (Cl2), and then delivering the cleaning gas to the processing region312of the process chamber during a period of time when the cleaning process is being performed.

Precursor Delivery System(s) and Delivery Method

The process of forming one or more layers containing multiple chemical elements on a surface of a substrate by use of a chemical vapor deposition process can be very complex. The deposition process can be especially complex when the composition of the deposited one or more layers is adjusted by the adjusting the composition of a multi-component precursor gas during different stages of the deposition process. As briefly discussed above, chemical vapor deposition processes generally require the formation of precursor gases by the generation of a vapor from a solid or liquid precursor source material that is disposed in an ampoule that is positioned within either of the gas source assemblies304or305. Since the solid or liquid precursor material found in the ampoules typically each have a differing vapor and/or sublimation rate at a given temperature and pressure maintained within the inner volume of the ampoules, the desired composition of a multi-component precursor gases, and thus composition of the deposited film, is hard to control. Also, controlling the repeatable delivery of a multi-component precursor gas for each substrate processed in a process chamber, due to common problems that are often created by the starting and stopping of the flows of the multiple precursor gases, is also a challenge. These common problems are often created from “gas bursts” and/or gas flow fluctuations generated by the stagnation of the precursor gases during substrate transfer or chamber processing idle times and the variable flow often created by the process recipe or normal cyclic variation created by the repetitive sequential substrate processing in the process chamber. Therefore, to solve these common problems found when delivering a multi-component precursor gas, embodiments of the disclosure provided herein may provide a multi-component precursor gas delivery assembly that is able to reliably form the multiple chemical element containing deposited film. In one example, the multiple chemical element containing deposited film is an IGZO containing layer.

FIG. 4is a schematic illustration of one configuration of the gas source assembly304that includes a precursor delivery system430, according to an embodiment of the disclosure. The precursor delivery system430of the gas source assembly304is adapted to deliver a multi-component precursor gas to the processing region312of a process chamber300to form one or more layers containing multiple chemical elements on a surface of a substrate340. In one example, the gas source assembly304is adapted to deliver a multi-component precursor gas that includes tri-methyl-indium (TMI), tri-methyl-gallium (TMG) and diethylzinc (DEZn) in a desired ratio, and the gas source assembly305may be configured to provide an oxygen containing gas, to form an IGZO layer that has a desirable composition and properties on a surface of the substrate340. In one embodiments, the multi-component precursor gas includes a precursor gas selected from the group consisting of tri-methyl-indium (TMI), tri-methyl-gallium (TMG), diethylzinc (DEZn), tri-ethyl-gallium (TEGa), and di-methyl-zinc (DMZn).

In one embodiment, the gas source assembly304may include a precursor delivery system430, a vent line assembly420and a precursor line assembly410that are used to reliably deliver a desired amount of a multi-component precursor gas to the processing region312. The precursor delivery system430generally includes a plurality of precursor delivery systems, such as precursor delivery systems432,434and436, that are each used to deliver a type of precursor gas to the inlet line304A, and thus deliver a multi-component precursor gas to the processing region312. The precursor delivery systems432,434and436each generally include a vapor delivering source assembly440(e.g., source assemblies440A-C), a push gas assembly450(e.g., push gas assemblies450A-C), a back pressure regulator455(e.g., back pressure regulators455A-C), output valves456A-B,457A-B,458A-B and an ampoule (e.g., ampoules433A,435A or437A). WhileFIG. 4Illustrates a configuration in which the precursor delivery system430is coupled to the precursor plenum319A, this configuration is not intended to be limiting as to the scope of the disclosure described herein, since the precursor delivery system430could be coupled to the precursor plenum319B instead of the precursor plenum319A, and the precursor plenum319A could be configured to deliver the second precursor gas, which is discussed above.

The vapor delivering source assemblies440A,440B and440C each generally include a gas source441A,441B,441C and a flow controller442A,442B,442C that are each configured to deliver a desired flow of gas to the ampoules433A,435A or437A, respectively, to cause a vapor generated from the solid/liquid precursor material433B,435B,437B to flow into a vapor delivery line443A,443B and443C. In some configurations the solid/liquid precursor material433B,435B,437B in the ampoules433A,435A or437A may be maintained at a desirable temperature by a thermal control assembly438A,438B,438C (e.g., thermal blanket, closed-loop chilled fluid supply, etc.). The flow controller442A,442B,442C may include a mass flow controller (MFC) that is able to control the amount of gas flow into the vapor delivery line443A,443B and443C, respectively, based on a pressure set by the back pressure regulators455A-C. In some configurations, the gas sources441A,441B,441C are each configured to provide one or more carrier gases to its respective flow controller442A,442B,442C and an inner volume of the ampoule433A,435A,437A. In one example, the gas source441A is configured to simultaneously provide two carrier gases to the inner volume of the ampoule, such as a gas containing nitrogen (N2) and argon (Ar). It is believed that the delivery of an nitrogen and inert gas (e.g., argon gas) mixture will be useful in the formation of an IGZO layer using a PECVD process, due to the presence of these different mass gases that will interact with and bombard the substrate surface during the IGZO deposition process.

The push gas assemblies450A,450B, and450C each generally include a gas source451A,451B,451C and a flow controller452A,452B,452C that are configured to deliver a desired flow of gas to the vapor delivery lines443A,443B and443C, respectively, to push the vapor generated from the solid/liquid precursor material433B,435B,437B through the back pressure regulators455A-C and into either the precursor line assembly410or the vent line assembly420. The flow controller452A,452B,452C may include a mass flow controller (MFC) that is able to control the amount of gas flow into the vapor delivery line443A,443B and443C, respectively, based on a pressure set by the back pressure regulators455A-C. In some configurations, the gas sources451A,451B,451C are each configured to provide one or more carrier gases to its respective flow controller452A,452B,452C and vapor delivery line443A,443B and443C. In one example, the gas source451A is configured to simultaneously provide two carrier gases to the inner volume of the ampoule, such as a gas containing nitrogen (N2) and argon (Ar).

The precursor line assembly410is coupled to the inlet line304A which is connected to the precursor plenum319A of the gas distribution plate assembly318. The precursor line assembly410is adapted to receive one or more of the precursor gases from each of the precursor delivery systems432,434and436at one or more times during a deposition process performed in the process chamber300. The precursor line assembly410may include a gas source413and a flow controller412that is configured to deliver a desired flow of gas through the inlet line304A to cause a precursor vapor injected into the line from each of the precursor delivery systems432,434and436to flow into inlet line304A and into the processing region312through the precursor plenum319A and gas conduits323. The flow controller412within the gas source413may include an MFC that is able to control the amount of gas flow within the inlet line304A at a desired rate. In some configurations, the gas source413is configured to provide one or more carrier gases to the flow controller412and inlet line304A. In one example, the gas source413is configured to simultaneously provide two carrier gases to the inner volume of the flow controller412, such as a gas containing nitrogen (N2) and argon (Ar). In some configurations, the flow controller412is configured to deliver a constant, or minimally varying flow, of the one or more carrier gases through the inlet line304A.

The vent line assembly420is coupled to the exhaust line307A that is connected to the exhaust pump307. The vent line421is also adapted to receive one or more of the precursor gases from each of the precursor delivery systems432,434and436at one or more times during a deposition process performed in the process chamber300. The vent line assembly420may include a gas source423and a flow controller422that is configured to deliver a desired flow of gas to the exhaust line307A to allow a vapor injected within the line from each of the precursor delivery systems432,434and436to flow into exhaust line307A and then be exhausted from the process chamber300. The flow controller422may include an MFC that is able to control the amount of gas flow within the exhaust line307A. In some configurations, the gas source423is configured to provide one or more carrier gases to the flow controller422and exhaust line307A at a desired rate. In one example, the gas source423is configured to simultaneously provide two carrier gases to the inner volume of the flow controller422, such as a gas containing nitrogen (N2) and argon (Ar). In some configurations, the flow controller422is configured to deliver a constant, or minimally varying flow, of the one or more carrier gases through the vent line421.

During operation, and based on software instructions contained within the memory294of the system controller290, the system controller290is configured to command the components in the precursor delivery system430to deliver a desired mixture of the vaporized solid/liquid precursor material433B,435B,437B to form a multi-element containing layer on a surface of the substrate340that is disposed in the processing region312of the process chamber300. Due to the differing vapor and/or sublimation rates of the solid/liquid precursor material433B,435B,437B used to form a multi-component precursor gas, the system controller290will generally deliver control signals to the flow controllers442A,442B and442C and the flow controllers452A,452B and452C to cause a desired flow rate of each type of precursor gas to flow through their respective vapor delivery line443A,443B or443C, their respective back pressure regulator455A,455B and455C and into the inlet line304A so that they mix and are then delivered to processing region312. Based on the vaporization rate of each solid/liquid precursor material433B,435B,437B the desired gas flow rates form each precursor delivery systems432,434and436is set so that a desired mass flow rate for each precursor gas is reached to form a multi-component precursor gas that has a desired composition. In one example, the flow rates for tri-methyl-indium (TMI), tri-methyl-gallium (TMG) and diethylzinc (DEZn) have a ratio of 80:1:10, respectively, while the inner volume of the ampoules are maintained at a pressure of about 760 Torr, to form a multi-component precursor gas that can form an IGZO layer having a In:Ga:Zn composition ratio of about 1:1:1. The back pressure regulators455A,455B and455C are typically set so that the flow provided by each precursor delivery systems432,434and436is at a desired rate. In one example, the back pressure regulators455A,455B and455C are set to the same pressure level so that the generated precursor gases can be combined within the inlet line304A and/or the precursor plenum319A in stable and minimally varying way, even when scheduled and unscheduled multi-component precursor gas flows and process chamber pressure variations, which are upstream of the back pressure regulators455A,455B and455C, occur.

Moreover, to avoid the fluctuations in the flow of the multi-component precursor gas, and possibly the composition of the multi-component precursor gas, due to the stopping and starting of the precursor gas flow during process chamber idle or other similar times, the precursor gases delivered through the vapor delivery lines443A,443B or443C is maintained at a desired flow rate, but is diverted through the output valves456A,457A,458A and into the vent line421when the chamber is not ready to receive the multi-component precursor gas. In some cases, the flow rate provided by the flow controllers442A,442B and442C and flow controllers452A,452B and452C is reduced while the precursor gases are delivered into the vent line421and into the exhaust pump307. Next, when the multi-component precursor gas is to be delivered to the processing region312the output valves456A,457A,458A are closed and the output valves456B,457B,458B are opened to allow the precursor gases to be delivered into processing region312through the inlet line304A. In some embodiments, the flow of each of the precursor gases by each precursor delivery systems432,434or436are never stopped, and thus the problems associated with the stopping and starting of the precursor gas flow will not occur. In one configuration, the time between first delivering the precursor gas flow to the vent line421and then to the inlet line304A, and vice versa, is minimized and is in some cases nonexistent (e.g., switched directly from one state to the other). One will appreciate that this problem is additionally complex, due to the need to separately control a plurality of separate precursor delivery systems whose outputs are fluidly coupled together, and thus a fluctuation in one output will affect the output of the others.

In some embodiments of the precursor delivery system430, a differential pressure control system460is used to control the variation in pressure between the inlet line304A and vent line421to further minimize the variability in the multi-component precursor gas flow to the processing region312from the inlet line304A. In this configuration, the differential pressure control system460is able to adjust and maintain a set differential pressure between the inlet line304A and vent line421, by use of one or more back pressure regulator controllers (not shown) that is communication with the vent line421. The back pressure regulator controller is typically configured to control the pressure differential between the vent line421and inlet line304A by allowing an amount of gas to flow from the inlet line304A to the vent line421as needed to maintain the desired pressure differential. Therefore, during the operation of the process chamber300, when the pressure within the processing region312, exhaust pump307and/or exhaust line307A vary due to normal or unscheduled pressure variations, the flow variation in the multiple component precursor gas flow into the inlet line304A can be minimized.

In one embodiment, the precursor delivery system430may include at least one precursor delivery system (not shown), which is similar to the precursor delivery systems432,434or436described above, that is adapted to provide a precursor gas to form one or more additional layers on a layer that is formed by the formation and delivery of the multi-component precursor gas to the surface of the substrate, as discussed above. In one example, a process performed in the chamber300may include the formation of an IGZO layer as discussed above, and then a second layer, such as aluminum oxide (Al2O3) is formed thereon by use of one or more of the components found in the precursor delivery system430. The precursor delivery system430may thus additionally include one or more additional precursor delivery systems that are each used to deliver a type of precursor gas to the inlet line304A. The additional precursor delivery systems will also each generally include a vapor delivering source assembly440, a push gas assembly450, a back pressure regulator455, output valves456A,457A,458A, and an ampoule, as discussed above. In one example, the precursor delivery system430is configured to deliver an indium containing precursor gas (e.g., tri-methyl-indium (TMI)) from a first precursor delivery system432, a gallium containing precursor gas (e.g., tri-methyl-gallium (TMG), tri-ethyl-gallium (TEGa)) from a second precursor delivery system434, a zinc containing precursor gas (e.g., diethylzinc (DEZn), di-methyl-zinc (DMZn)) from a third precursor delivery system436, and an aluminum containing precursor gas (tri-methyl-aluminum (TMA)) from a fourth precursor delivery system (not shown) to processing region312through the inlet line304A or into the exhaust line307A.

Although several preferred embodiments which incorporate the teachings of the present disclosure have been shown and described in detail, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings.