Deposition radial and edge profile tunability through independent control of TEOS flow

Disclosed embodiments generally relate to a processing chamber that includes a perforated lid, a gas blocker disposed on the perforated lid, and a substrate support disposed below the perforated lid. The gas blocker includes a gas manifold, a central gas channel formed in the gas manifold, a first gas distribution plate that includes inner and outer trenches surrounding the central gas channel, and a first and second gas channels formed in the gas manifold. The first gas channel is in fluid communication with a first gas source and the inner trench, and the second gas channel is in fluid communication with the first gas source and the outer trench and a second gas distribution plate The first gas channel is in further fluid communication with a third gas distribution plate that is disposed below the second gas distribution plate, and a plurality of pass-through channels that are disposed between the second gas distribution plate and the third gas distribution plate. The second gas distribution plate includes a plurality of through holes formed through a bottom of the second gas distribution plate as well as a central opening in fluid communication with the central gas channel The second gas distribution plate further includes a recess region formed in a top surface of the second gas distribution plate, and the recess region surrounds the central opening.

BACKGROUND

Field

Embodiments of the disclosure generally relate to an improved method and apparatus for controlling deposition near an edge of the substrate.

Description of the Related Art

Plasma enhanced chemical vapor deposition (PECVD) is generally employed to deposit thin films on a substrate such as a flat panel or semiconductor wafer. Plasma enhanced chemical vapor deposition is generally accomplished by introducing a precursor gas into a vacuum chamber that contains a substrate. The precursor gas is typically directed through a distribution plate disposed near the top of the chamber. The precursor gas in the chamber is energized (e.g., excited) to form a plasma by applying RF power to the chamber from one or more RF sources coupled to the chamber. The excited gas reacts to form a layer of material on a surface of the substrate that is positioned on a temperature controlled substrate support.

It has been observed that the distribution of precursor gases in the chamber may result in varying plasma densities across the surface of the substrate, causing different deposition rates between the center and the edge of the substrate. Therefore, there is a need in the art for an improved method and apparatus with better control of gas distribution.

SUMMARY OF THE DISCLOSURE

In one embodiment, a processing chamber for processing a substrate is provided. The processing chamber includes a perforated lid, a gas blocker disposed on the perforated lid, and a substrate support disposed below the perforated lid. The gas blocker includes a gas manifold, a central gas channel formed in the gas manifold, a first gas distribution plate disposed below the gas manifold, the first gas distribution plate comprising an inner trench surrounding the central gas channel and an outer trench surrounding the inner trench, a first gas channel formed in the gas manifold, the first gas channel having a first end in fluid communication with a first gas source and a second end in fluid communication with the inner trench, a second gas channel formed in the gas manifold, the second gas channel having a first end in fluid communication with the first gas source and a second end in fluid communication with the outer trench, a second gas distribution plate disposed below the first gas distribution plate, a third gas distribution plate disposed below the second gas distribution plate, the third gas distribution plate comprising a plurality of through holes formed through a bottom of the third gas distribution plate, and the third gas distribution plate contacting a top surface of the perforated lid, and a plurality of pass-through channels disposed between the second gas distribution plate and the third gas distribution plate, and each pass-through channel being extended through the perforated lid. The second gas distribution plate includes a plurality of through holes formed through a bottom of the second gas distribution plate, a central opening in fluid communication with the central gas channel, and a recess region formed in a top surface of the second gas distribution plate, the recess region surrounds the central opening.

In another embodiment, the processing chamber includes a first gas source comprising a first gas line and a second gas line, a perforated lid, a gas blocker disposed on the perforated lid, and a substrate support disposed below the perforated lid, the substrate support having a substrate supporting surface. The gas blocker includes a gas manifold, a central gas channel formed in the gas manifold, a first gas distribution plate disposed below the gas manifold, the first gas distribution plate comprising an inner trench surrounding the central gas channel and an outer trench surrounding the inner trench, a first gas channel formed in the gas manifold, the first gas channel having a first end in fluid communication with the first gas line and a second end in fluid communication with the inner trench, a second gas channel formed in the gas manifold, the second gas channel having a first end in fluid communication with the second gas line and a second end in fluid communication with the outer trench, a second gas distribution plate disposed below the first gas distribution plate, the second gas distribution plate comprising a plurality of through holes formed through a bottom of the second gas distribution plate, a third gas distribution plate disposed below the second gas distribution plate, and the third gas distribution plate comprising a plurality of through holes formed through a bottom of the third gas distribution plate, and the third gas distribution plate contacts a top surface of the perforated lid.

To facilitate understanding, identical reference numerals have been used, wherever possible, to designate identical elements that are common to the figures.

DETAILED DESCRIPTION

FIG. 1depicts a top view of an exemplary tandem processing system100according to embodiments of the present disclosure. The processing system100includes two separate and adjacent processing chambers101,103for processing the substrates. The processing chambers101,103can share a first gas source112disposed adjacent to the processing chambers101,103. The first gas source112is coupled to the processing chambers101,103through a first gas line118and a second gas line119, respectively. The exemplary tandem processing system100may be incorporated into a processing system, such as a Producer™ processing system, commercially available from Applied Materials, Inc., of Santa Clara, Calif. It is to be understood that the disclosure also has utility in processing systems manufactured by other manufacturers.

The first gas source112may include a vaporizer145for vaporizing liquid precursor, such as tetraethoxysilane (TEOS). At least one heater147is coupled to the vaporizer145and heats the liquid precursor into a gas phase. The precursor gas is delivered to the first gas line118and/or the second gas line119and then to the processing chambers101,103. The first gas source112may contain one or more precursor sources, depending on the application. In some embodiments, the first gas source112may contain a source for a first gas mixture and a source for a second gas mixture. The first gas mixture may flow through the first gas line118and the second gas mixture may flow through the second gas line119.

The first gas mixture and the second gas mixture may be suitable for depositing a dielectric material, such as silicon oxides. In one embodiment, the first gas mixture includes an oxygen-containing gas, a silicon-containing gas, and a carrier gas, while the second gas mixture includes the oxygen-containing gas and the carrier gas, or vice versa. Suitable oxygen-containing gas may include oxygen (O2), ozone (O3), carbon dioxide (CO2), carbon monoxide (CO), nitrous oxide (N2O), nitrous oxide (N2O), nitric oxide (NO), or any combination thereof. Suitable silicon-containing gas may include silanes, halogenated silanes, organosilanes, and any combinations thereof. Silanes may include silane (SiH4), tetraethoxysilane (TEOS), and higher silanes with the empirical formula SixH(2x+2), such as disilane (Si2H6), trisilane (Si3H8), and tetrasilane (Si4H10), or other higher order silanes such as polychlorosilane. Suitable carrier gases include argon, nitrogen, hydrogen, helium, or other suitable inert gases. Carrier gas may be used for carrying vaporized silicon-containing gas, such as TEOS.

In some embodiments, a second gas source123may be coupled to, through a third gas line125, a central gas channel129of the processing chambers101,103. The central gas channel129is in fluid communication with the substrate processing region108(FIG. 2) of the processing chambers101,103. The second gas source123may include any suitable process precursor, such as the silicon-containing gas discussed above. Likewise, the second gas source123may include a vaporizer (not shown) and a heater (not shown) for vaporizing liquid precursor, such as TEOS. In an embodiment, the second gas source123includes a source of a third gas mixture containing silanes, such as TEOS.

In various embodiments to be discussed below, the first gas mixture and the second gas mixture may be routed to the inner gas zone120and outer gas zone142of the substrate processing region108, respectively. The third gas mixture may be provided to the central gas channel129. The third gas mixture, the first gas mixture and the second gas mixture are excited to form a plasma using capacitive or inductive means. These gas mixtures are decomposed in the plasma to deposit a layer of oxide, e.g., silicon oxide, on the surface of a substrate located in the processing chambers101,103.

FIG. 2depicts a cross-sectional view of the processing chamber101according to embodiments of the present disclosure. It should be understood that while only a portion of the processing system100, e.g., the processing chamber101, is shown, the description for the processing chamber101is equally applicable to the processing chamber103since the configuration of the processing chambers101,103are substantially identical. Therefore, the operation and processing occurred in the processing chamber101can similarly and concurrently be performed in the processing chamber103. The processing chamber101has a perforated lid102, a gas blocker105disposed on the perforated lid102, a chamber wall104, and a bottom106. The perforated lid102, the chamber wall104and the bottom define the substrate processing region108where a substrate (not shown) is to be disposed. The substrate processing region108can be accessed through a port (not shown) in the chamber wall104that facilitates movement of the substrate into and out of the processing chamber101.

A substrate support109is disposed within the processing chamber101and surrounded by the chamber wall104. The substrate supporting surface of the substrate support109may have a plurality of holes242distributed evenly across the substrate supporting surface. The holes242are adapted to permit the flow of gases through the substrate supporting surface for cooling or heating of the substrate disposed thereon. The substrate support109may couple to a stem131that extends through the bottom106of the processing chamber101. The stem131can be operated by a drive system (not shown) to move the substrate support109up and down, thereby changing the position of the substrate in the substrate processing region108. The drive system can also rotate and/or translate the substrate support109during processing. The substrate support109and the substrate processing region108are configured to accommodate substrate having a nominal diameter size up to 12 inch (300 mm), 18 inch (450 mm), or other diameter.

The perforated lid102is supported by the chamber walls104and can be removed to service the interior of the processing chamber101. The perforated lid102is generally comprised of aluminum, aluminum oxide, aluminum nitride, stainless steel, or any other suitable material. The gas blocker105disposed on the perforated lid102is a dual zone gas blocker configured to independently control the flow of two or more gas mixtures into the substrate processing region108. The gas blocker105is in fluid communication with the first gas source112and the second gas source123. In an example as shown, the first gas source112is connected to the gas blocker105through the first gas line118and the second gas line119, respectively. The first gas line118may be connected to the first gas source112to provide the first gas mixture, e.g., the silicon-containing gas, the oxygen-containing gas, and the carrier gas, into the processing chamber101. The second gas line119may be connected to the first gas source112to provide the second gas mixture, e.g., oxygen-containing gas and the carrier gas, into the processing chamber101. The first gas line118may be heated and actively controlled to ensure that gas (e.g., TEOS) remains in the gas phase while traveling with the carrier gas to the processing chamber101.

The gas blocker105generally includes a gas manifold212, a first gas distribution plate214disposed below the gas manifold212, a second gas distribution plate216disposed below the first gas distribution plate214, and a third gas distribution plate218disposed below the second gas distribution plate216. The central gas channel129is formed through at least the gas manifold212and the first gas distribution plate214. The gas manifold212, the first gas distribution plate214, the second gas distribution plate216, and the third gas distribution plate218are concentrically disposed about a central axis passing through the longitudinal axis of the central gas channel129. The first gas distribution plate214may include one or more heat transfer fluid channels121. The heat transfer fluid channels121can be used for regulating the temperature of the gas blocker105and/or the perforated lid102by flowing heat transfer fluid therethrough. Suitable heat transfer fluid may include, but is not limited to, water, air, helium, etc. The first gas distribution plate214may also include a pumping plenum114that fluidly connects the substrate processing region108to an exhaust port (that includes various pumping components, not shown).

The second gas distribution plate216has a central opening124, and a recess region128formed in the top surface of the second gas distribution plate216. The recess region128surrounds the central opening124and extends radially between the central opening124and the edge of the second gas distribution plate216. The bottom of the first gas distribution plate214and the bottom of the second gas distribution plate216define a plenum for the recess region128. The central opening124is in fluid communication with the central gas channel129. In an embodiment, the central opening124has a diameter greater than the diameter of the central gas channel129. The second gas distribution plate216has a plurality of through holes126formed through the bottom of the second gas distribution plate216. The through holes126may be arranged in any suitable pattern. In one embodiment, the through holes126are arranged in multiple concentric rings of increasing diameter.

The third gas distribution plate218has a recess region220formed in the top surface of the third gas distribution plate218. The bottom of the third gas distribution plate218contacts a top surface of the perforated lid102. The bottom of the second gas distribution plate216and the bottom of the third gas distribution plate218define a plenum for the recess region220. An inner ring138and an outer ring140are concentrically disposed on the bottom of the third gas distribution plate216between the second gas distribution plate216and the third gas distribution plate218. The outer ring140surrounds the inner ring138. The inner ring138and the outer ring140may be fabricated from aluminum, aluminum oxide, aluminum nitride, stainless steel, or other suitable material such as dielectric material. The inner ring138and the outer ring140can separate the recess region220into an inner gas zone120and an outer gas zone142. For example, the region radially inward of the inner ring138can be defined as the inner gas zone120. The region between the inner ring138and the outer ring140and the region radially outward of the outer ring140can be collectively defined as the outer gas zone142. In cases where the third gas distribution plate has a diameter of about 360 mm, the inner gas zone120may start at a radial distance of about 20 mm or greater, for example about 30 mm to about 60 mm. The outer gas zone142may start at a radial distance of about 60 mm or greater, for example about 75 mm to 110 mm, measuring from the center of the third gas distribution plate218.

The third gas distribution plate218has a plurality of through holes132formed through the bottom of the third gas distribution plate218. The through holes132of the third gas distribution plate218may have a density greater than the density of the through holes126of the second gas distribution plate216. In an example, the ratio of the density of the through holes132to the density of the through holes126can be in a range of about 1.5:1 to about 5:1, for example about 2:1 to about 3:1. The through holes132may be arranged in a radial pattern across the diameter of the third gas distribution plate218to allow uniform delivery of the gas into the substrate processing region108.

The gas blocker105also includes a first gas channel116and a second gas channel117. The first gas channel116and the second gas channel117are disposed to extend through at least a portion of the gas manifold212. The first gas channel116is disposed radially outward of the central gas channel129, and the second gas channel117is disposed radially outward of the first gas channel116. The first gas channel116has a first end connected to, or in fluid communication with, the first gas line118, and a second end connected to, or in fluid communication with, an inner trench222formed in the top surface of the first gas distribution plate214. Similarly, the second gas channel117has a first end connected to, or in fluid communication with, the second gas line119, and a second end connected to, or in fluid communication with, an outer trench224formed in the top surface of the first gas distribution plate214. The inner trench222and the outer trench224are arranged in two concentric circles surrounding the central gas channel129. The first gas channel116may be disposed at any location along the inner trench222, and the second gas channel117may be disposed at any location along the outer trench224. The inner trench222has a first depth D1measuring from the top surface of the first gas distribution plate214. The outer trench224has a second depth D2measuring from the top surface of the first gas distribution plate214. The first depth D1may be shorter or greater than the second depth D2. In an example as shown, the first depth D1is greater than the second depth D2. In an example, the ratio of the first depth D1to the second depth D2is about 1.1:1 to about 1.5:1, for example about 1.3:1.

In some embodiments, the gas blocker105may include a third gas channel240disposed through at least a portion of the gas manifold212. The third gas channel240may be in fluid communication with the first and second gas sources112,123, or any other gas source containing any suitable gas source (e.g., nitrogen-containing gas source, or a dopant-containing gas source etc.) needed for the application. Likewise, the third gas channel240may be disposed radially outward of the central gas channel129, and the third gas channel240may be disposed at any location along the inner trench222so that the third gas channel240and the inner trench222are in fluid communication with each other.

The inner trench222is in fluid communication with the inner gas zone120through one or more inner gas channels226also formed in the first gas distribution plate214. The placement of the inner ring138confines the gas mixture (e.g., first gas mixture) flowing from the first gas channel116to the inner gas zone120. The first gas mixture is then flowed through the perforated lid102and to the inner region of the substrate processing region108. The inner region of the substrate processing region108(and thus the substrate disposed on the substrate support109) substantially corresponds to the inner gas zone120. The arrow230illustrates a possible flow path of the gas mixture from the first gas line118to the substrate processing region108. Likewise, the outer trench224is in fluid communication with the recess region128of the second gas distribution plate216through one or more outer gas channels228also formed in the first gas distribution plate214. The placement of the outer ring140confines the gas mixture (e.g., second gas mixture) flowing from the second gas channel117to the recess region128and into the outer gas zone142. The second gas mixture is then flowed through perforated lid102and to the outer region of the substrate processing region108. The outer region of the substrate processing region108(and thus the substrate disposed on the substrate support109) substantially corresponds to the outer gas zone142. While not shown, it should be understood that the perforated lid102has through holes corresponding to the through holes132of the third gas distribution plate218. The arrow236illustrates a possible flow path of the gas mixture from the second gas line119to the substrate processing region108. The arrow238illustrates a possible flow path of the gas mixture from the third gas line125to the substrate processing region108.

In some embodiments, the gas blocker105may include a plurality of pass-through channels (e.g., pass-through channels232,234) disposed between the second gas distribution plate216and the third gas distribution plate218. Each pass-through channel is configured to directly route the gas mixture (e.g., second gas mixture) from the recess region128of the second gas distribution plate216into the substrate processing region108. The pass-through channels may be disposed radially inward of the inner ring138. The pass-through channels may be provided in any number. For example, four pass-through channels (only two pass-through channels232,234are shown for clarity) may be provided and angularly separated from each other by 90 degrees. The pass-through channels232,234may form through the bottom of the second gas distribution plate216and extend into the bottom of the third gas distribution plate218and into the perforated lid102. In some embodiments, the pass-through channels may extend through the entire thickness of the perforated lid102. The pass-through channels232,234allow the gas mixture (e.g., second gas mixture) to pass through the recess region220without being mixed prematurely with the gas mixture (e.g., first gas mixture) flowing from the first gas channel116and/or the gas mixture flowing through the central gas channel129.

The perforated lid102and the substrate support109may serve as upper and bottom electrodes, respectively, for exciting and ionizing the gas mixtures in the substrate processing region108. A bias power may be applied to the substrate support109. The substrate support109may be grounded such that the perforated lid102supplied with an RF power (provided by a power source156) may serve as a cathode electrode, while the grounded substrate support108may serve as an anode electrode. The perforated lid102and the substrate support109are operated to form an RF electric field in the substrate processing region108. The RF electric field can ionize the gas mixtures into a plasma. If desired, any one or more of the first, second and third gas distribution plates214,216,218may serve as an electrode and operate to excite and ionize the gas mixtures in the recess region128,220. The RF power, generally having a frequency of between a few Hz to 13 MHz or higher, is provided in a wattage suitable for the substrate surface area. In one embodiment, the power source156includes a dual frequency source that provides a low frequency power at less than about 2 MHz (preferably about 200 to 500 kHz) and a high frequency power at greater than 13 MHz (preferably about 13.56 MHz). The frequencies may be fixed or variable. Illustratively, for a 300 mm substrate, the low frequency power may be about 0.3 to about 2 kW while the high frequency power may be about 1 to about 5 kW.

FIG. 3depicts a simplified cross-sectional view of the processing chamber101ofFIG. 2having a substrate302disposed on the substrate support109.FIG. 3shows exemplary flow paths of the first, second, and third gas mixtures (represented by arrows230,236,238, respectively) from the first and second gas sources112,123to the substrate processing region108according to embodiments of the present disclosure. As can be seen, the placement of the inner ring138and the outer ring140can restrict all or the majority of the first gas mixture230from the first gas line118and the third gas mixture238from the third gas line125to the inner gas zone120, and restrict all or the majority of the second mixture gas236from the second gas line119to the outer gas zone142. Therefore, the first and third gas mixtures230,238from the first gas line118and third gas line125, such as TEOS, O2and argon, will pass the through holes of the third gas distribution plate218located within the inner ring138, and flow downwardly through the perforated lid102toward the inner region of the substrate processing region108. As the first and third gas mixtures230,238approach the substrate support109, the flows curve into radial outward flows along the top surface304of the substrate support109. The radial outward flows of the first and third gas mixtures230,238continue to the outer region of the substrate processing region108, maintaining flows of the first and third gas mixtures230,238from the inner region of the substrate processing region108to its perimeter. In the meantime, the second gas mixture236from the second gas line119, such as oxygen and argon gases, will pass the through holes of the second and third gas distribution plates216,218, and flow downwardly through the perforated lid102toward the outer region of the substrate processing region108. Particularly, as the second gas mixture236approaches the radial outward flows of the first and third gas mixtures230,238, the flow of the second gas mixture236curves into a radial outward flow and flows with the radial outward flows of the first and third gas mixtures230,238toward the edge of the substrate processing region108. The first, second, and third gas mixtures230,236,238are ionized and form a plasma while flowing into the substrate processing region108for deposition of a layer, such as silicon oxide, on the substrate disposed on the substrate support109in an uniform manner.

It has been observed that inefficient TEOS concentration can occur near the edge of the substrate support109(and thus the substrate disposed thereon) due to the presence of surface boundary layer, which may result in varying plasma densities across the surface of the substrate and cause different deposition rates between the center and the edge of the substrate. The configuration of the gas blocker105offers many advantages as it can restrict the flow of TEOS to the inner region of the substrate processing region108while allowing a dedicate flow of the oxygen and argon gases (e.g., second gas mixture236) to the outer region of the substrate processing region108. The addition of oxygen and argon gas (e.g., second gas mixture236) to the outer region of the substrate processing region108can confine the flow of TEOS, O2and Ar (e.g., first and third gas mixtures230,238) within the inner region of the substrate processing region108and maintain the residence time of TEOS within the inner region of the substrate processing region108. The addition of oxygen and argon gas to the outer region of the substrate processing region108can also promote gas reaction at or near the edge of the substrate support105, thereby enhancing the TEOS concentration near the edge of the substrate. Since the TEOS concentration at the edge of the substrate is increased, the plasma density at the substrate edge during processing can be increased accordingly. As a result, a uniform deposition rate between the center and the edge of the substrate can be obtained.

Moreover, it has been observed that the arrangement of the inner ring138and the outer ring140can be used to adjust the film deposition rate (and thus the film profile across the substrate surface). For example, the outer peripheral surface of the inner ring138may be disposed at a radial distance of about 75 mm, for example about 80 mm to 90 mm, measuring from the center of the substrate110, to provide gas split of about 27% of the total gas flow at the inner gas zone120and about 73% of the total gas flow at the outer gas zone142. The term total gas flow described herein refers to total flow of the gas mixtures present in the recess region220. This arrangement can yield good deposition uniformity across the substrate surface.

Furthermore, it has been observed that varying about 2-4% of TEOS flow (negligible amount of flow in the total process flow) in the inner region of the substrate processing region108can result in about 5-10% change in deposition rates and film profile without affecting film properties. For example, a 2% increase of TEOS flow in the inner region of the substrate processing region108can result in a 2.6% increase in deposition rate on the inner region of the substrate. A 4% increase of TEOS flow in the inner region of the substrate processing region108can result in a 5.5% increase in deposition rate on the inner region of the substrate. In addition, a 2% decrease of TEOS flow in the inner region of the substrate processing region108can result in a 2.0% decrease in deposition rate on the inner region of the substrate. A 4% decrease of TEOS flow in the inner region of the substrate processing region108can result in a 4.2% decrease in deposition rate on the inner region of the substrate.

Likewise, it has been observed that varying about 2-4% of TEOS flow (negligible amount of flow in the total process flow rate) in the outer region of the substrate processing region108can result in about 1-2% change in deposition rates and film profile without affecting film properties. For example, a 2% increase of TEOS flow in the outer region of the substrate processing region108can result in a 0.9% increase in deposition rate on the outer region of the substrate. A 4% increase of TEOS flow in the outer region of the substrate processing region108can result in a 1.5% increase in deposition rate on the outer region of the substrate. In addition, a 2% decrease of TEOS flow in the outer region of the substrate processing region108can result in a 0.1% increase in deposition rate on the outer region of the substrate. A 4% decrease of TEOS flow in the outer region of the substrate processing region108can result in a 0.6% decrease in deposition rate on the inner region of the substrate.

In either case above, the total process flow of the gas mixtures in the inner gas zone120/outer gas zone142may be about 10,500 sccm and the total TEOS flow in the inner gas zone120/outer gas zone142may be about 177 sccm to about 1650 mgm. Therefore, varying 2% of the TEOS flow is about 3.55 sccm to about 33 mgm (about 0.034% of total gas flow). By changing the flow rate of TEOS in the first and third gas mixtures (flowing to the inner region of the substrate processing region108) and/or the flow rate of TEOS in the second gas mixture (flowing to the outer region of the substrate processing region108), the deposition rates of the layer, e.g., oxides, can be adjusted to tune the edge profile of the deposited layer and/or the overall layer uniformity on the substrate.