Patent Application
20160068958
Embodiments of the invention generally relate to apparatus and methods for controlling the temperature of a substrate during processing. In particular, embodiments of the invention are directed to apparatus and methods incorporating linear lamps to uniformly control the temperature of a large susceptor assembly to control the temperature of a plurality of substrates.
Dielectric and metal film (e.g, SiN, SiCN, TiN) atomic layer deposition processes require high wafer temperatures (generally greater than or equal to about 500° C.). These process temperature cannot be achieved using resistive heaters. Use of graphite heaters to reach high temperature is expensive. Additionally, resistive heaters and graphite heaters can cause contamination of the processed films. The installation and replacement of resistive and graphite heaters can be complex, difficult and expensive.
Lamps which can be used to radiatively heat the wafer can achieve high temperatures at low cost. Lamps are easier to install and replace compared to resistive and graphite heaters. The ramp up of wafer temperature is much faster with lamp heating compared to resistive or graphite heating. However, in processing chambers using large susceptor assemblies, lamp heating is not uniform. This results in a temperature gradient across the susceptor assembly which results in film deposition non-uniformity.
Therefore, there is a need in the art for methods and apparatus capable of controlling wafer temperature on large susceptor assemblies.
One or more embodiments of the invention are directed to processing chambers comprising a gas distribution assembly and a susceptor assembly. The susceptor assembly is below the gas distribution assembly and has a disk-shape including a top surface and a bottom surface defining a thickness. The top surface of the susceptor assembly includes at least one recess surface to support a wafer. A drive shaft supporting the susceptor assembly to rotate the susceptor assembly. A plurality of linear lamps are positioned beneath the susceptor assembly. The plurality of linear lamps separated into a plurality of zones. A controller is connected to the plurality of linear lamps to provide power independently to each of the zones of linear lamps.
In some embodiments, the susceptor assembly is sized to support at least three wafers.
In one or more embodiments, the susceptor has a diameter in the range of about 0.75 m to about 2 m.
In some embodiments, the linear lamps are arranged in concentric circles about the drive shaft. In one or more embodiments, wherein each of the linear lamps are substantially the same length.
In some embodiments, the plurality of linear lamps are substantially parallel to each other and extend perpendicularly to a diameter of the susceptor assembly. In one or more embodiments, the plurality of linear lamps have at least two different lengths.
Some embodiments further comprise at least two u-shaped lamps positioned around the drive shaft. In one or more embodiments, the at least two u-shaped lamps are positioned around the drive shaft to have a two-fold symmetry about the drive shaft. In some embodiments, a curved portion of each of the two u-shaped lamps are adjacent the drive shaft. In some embodiments, at least two u-shaped lamps define a first zone.
In one or more embodiments, the linear lamps are separated into at least two zones. In some embodiments, the linear lamps are separated into a second zone, a third zone and a fourth zone, each zone positioned further from the drive shaft and on opposite sides thereof. In one or more embodiments, the second zone comprises two linear lamps having a first length extending perpendicular to a diameter of the susceptor assembly and spaced a first distance along the diameter from the drive shaft so that the second zone is on opposite sides of the first zone, the third zone comprising at least one linear lamps having a second length shorter than the first length, the third zone positioned a second distance along the diameter from the drive shaft greater than the first distance so that the third zone is on opposite sides of the second zone and the fourth zone includes at least one lamp having the second length and/or at least one lamp having a third length shorter than the second length, the fourth zone positioned a third distance along the diameter from the drive shaft greater than the second distance so that the fourth zone is on opposite sides of the third zone.
In some embodiments, each of the linear lamps has an electrode at least one end of the lamp, the electrode bends downward away from the bottom surface of the susceptor assembly.
In one or more embodiments, the linear lamps include a reflective surface along a lower portion of the lamp to reflect light from the lamp toward the bottom surface of the susceptor assembly.
Additional embodiments of the invention are directed to processing chambers comprising a gas distribution assembly and a susceptor assembly. The susceptor assembly is below the gas distribution assembly and has a disk-shape including a top surface and a bottom surface defining a thickness. The top surface including at least one recess surface to support a wafer. A drive shaft supports the susceptor assembly to rotate the susceptor assembly. A plurality of linear lamps are positioned beneath the susceptor assembly. The plurality of linear lamps are separated into at least two zones and extend parallel to each other and perpendicular to a diameter of the susceptor assembly. At least two u-shaped lamps are positioned around the drive shaft to have two-fold symmetry about the drive shaft. A controller is connected to the plurality of linear lamps to provide power independently to each of the zones of linear lamps.
In some embodiments, the at least two u-shaped lamps define a first zone. In one or more embodiments, the linear lamps are separated into a second zone, a third zone and a fourth zone, each zone positioned further from the drive shaft and on opposite sides thereof. In some embodiments, the second zone comprises two linear lamps having a first length, the linear lamps extending perpendicular to a diameter of the susceptor assembly and spaced a first distance along the diameter from the drive shaft so that the second zone is on opposite sides of the first zone, the third zone comprising at least one linear lamps having a second length shorter than the first length, the third zone positioned a second distance along the diameter from the drive shaft greater than the first distance so that the third zone is on opposite sides of the second zone and the fourth zone includes at least one lamp having the second length and/or at least one lamp having a third length shorter than the second length, the fourth zone positioned a third distance along the diameter from the drive shaft greater than the second distance so that the fourth zone is on opposite sides of the third zone.
So that the manner in which the above recited features of the invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Embodiments of the invention are directed to apparatus and methods for creating a differential pressure developed from a unique precursor injector design with a magnitude sufficient to hold wafers in place at high rotation speeds. As used in this specification and the appended claims, the terms “wafer”, “substrate” and the like are used interchangeably. In some embodiments, the wafer is a rigid, discrete substrate.
The specific type of gas distribution assembly 120 used can vary depending on the particular process being used. Embodiments of the invention can be used with any type of processing system where the gap between the susceptor and the gas distribution assembly is controlled. While various types of gas distribution assemblies can be employed (e.g., showerheads), embodiments of the invention may be particularly useful with spatial ALD gas distribution assemblies which have a plurality of substantially parallel gas channels. As used in this specification and the appended claims, the term “substantially parallel” means that the elongate axis of the gas channels extend in the same general direction. There can be slight imperfections in the parallelism of the gas channels. The plurality of substantially parallel gas channels can include at least one first reactive gas A channel, at least one second reactive gas B channel, at least one purge gas P channel and/or at least one vacuum V channel. The gases flowing from the first reactive gas A channel(s), the second reactive gas B channel(s) and the purge gas P channel(s) are directed toward the top surface of the wafer. Some of the gas flow moves horizontally across the surface of the wafer and out of the processing region through the purge gas P channel(s). A substrate moving from one end of the gas distribution assembly to the other end will be exposed to each of the process gases in turn, thereby forming a layer on the substrate surface.
In some embodiments, the gas distribution assembly 120 is a rigid stationary body made of a single injector unit. In one or more embodiments, the gas distribution assembly 120 is made up of a plurality of individual sectors 122. A gas distribution assembly having either a single piece body or a multi-sector body can be used with the various embodiments of the invention described.
The susceptor assembly 140 is positioned beneath the gas distribution assembly 120. The susceptor assembly 140 includes an edge 144, a top surface 141 and a bottom surface 143 defining a thickness. The top surface 141 can include at least one recess 142 sized to support a substrate for processing. The recess 142 can be any suitable shape and size depending on the shape and size of the wafers 60 being processed. In the embodiment shown in
In some embodiments, as shown in
The susceptor assembly 140 of
In some embodiments, the gap 170 distance is in the range of about 0.1 mm to about 5.0 mm, or in the range of about 0.1 mm to about 3.0 mm, or in the range of about 0.1 mm to about 2.0 mm, or in the range of about 0.2 mm to about 1.8 mm, or in the range of about 0.3 mm to about 1.7 mm, or in the range of about 0.4 mm to about 1.6 mm, or in the range of about 0.5 mm to about 1.5 mm, or in the range of about 0.6 mm to about 1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, or in the range of about 0.8 mm to about 1.2 mm, or in the range of about 0.9 mm to about 1.1 mm, or about 1 mm.
The processing chamber 100 shown in the Figures is a carousel-type chamber in which the susceptor assembly 140 can hold a plurality of wafers 60. As shown in
Similarly, although not shown, the susceptor assembly 140 can be made up of a plurality of separately pieces or units. The plurality of units can be generally pie shaped and can be fitted together to form a susceptor assembly having a top surface and bottom surface.
The size of the susceptor assembly 140 can be varied depending on the specific processing chamber and the size of the wafers to be processed. In some embodiments, the susceptor assembly is sized to support at least three wafers. In one or more embodiments, the susceptor assembly is sized to support at least 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or more wafers. The wafers can be any size wafer including, but not limited to, 150 mm, 200 mm, 300 mm and 450 mm wafers. The diameter of the susceptor assembly can also vary. In some embodiments, the susceptor assembly has a diameter in the range of about 0.75 meters to about 2 meters, or in the range of about 1 meter to about 1.75 meters of in the range of about 1.25 meters to about 1.75 meters or about 1.5 meters.
Processing chambers having multiple gas injectors can be used to process multiple wafers simultaneously so that the wafers experience the same process flow. For example, as shown in
The processing chamber 100 shown in
The embodiment shown in
Rotation of the carousel (e.g., the susceptor assembly 140) can be continuous or discontinuous. In continuous processing, the wafers are constantly rotating so that they are exposed to each of the injectors in turn. In discontinuous processing, the wafers can be moved to the injector region and stopped, and then to the region 84 between the injectors and stopped. For example, the carousel can rotate so that the wafers move from an inter-injector region across the injector (or stop adjacent the injector) and on to the next inter-injector region where it can pause again. Pausing between the injectors may provide time for additional processing steps between each layer deposition (e.g., exposure to plasma).
Referring back to
The plurality of lamps 210 are linear lamps with spacing and zoning. As used in this specification and the appended claims, the term “linear lamp” means that the lamp is intended to be linear but that slight variations in the linearity are acceptable. For example, “linear lamps” may deviate from linearity by less than about 10%, 5%, 2% or 1%. The lamps, and processing chamber, are connected to a controller 240 which can independently control the susceptor assembly, gas distribution assembly, lamps and/or zones of lamps.
Each of the lamps 210 are parallel to each other and extend perpendicularly to a diameter 212 of the susceptor assembly. The diameter 212 is not an actual line, but merely a representation of a diameter. Those skilled in the art will understand that the lamps are spaced, for example, at increasing distances from the center of the susceptor assembly, where the drive shaft 160 is located.
The spacing between the lamps can vary or can be substantially the same. In some embodiments, the lamps are spaced in the range of about 15 mm to about 75 mm apart, or in the range of about 20 mm to about 70 mm apart, or in the range of about 25 mm to about 65 mm apart, or in the range of about 30 mm to about 60 mm apart, or in the range of about 35 mm to about 55 mm apart, or in the range of about 40 mm to about 50 mm apart.
Each of the lamps 210 in
Radiation from the lamps heat up the susceptor, and therefore, the wafer sitting on the susceptor. The wafers can reach a processing temperature greater than about 500° C. The lamp filaments reach much higher temperature, generally greater than about 1800° C. As the susceptor assembly rotates, the azimuthal temperature (temperature when susceptor assembly is stationary) variations are blended with the surrounding areas resulting in a radial temperature profile. The radial temperature profile can be modified and made more uniform by controlling the lamps in zones, instead of as a whole group.
Referring to
The lamps 210 shown in
There is a central region 222 which has no lamps 210. However, in some embodiments it may be desirable to include one or more lamps in this central region 222. Referring to
The u-shaped lamps 215 shown in
In some embodiments, the lamp 210 includes a reflective surface 219 along a lower portion of the lamp 210. The reflective surface 219 can reflect light from the lamp toward the bottom surface of the susceptor assembly. Additionally, the reflective surface 219 can help prevent the electrodes 211 from overheating by decreasing the amount of radiant energy impacting the electrodes. Suitable reflective surfaces include, but are not limited to, silver, gold, Al2O3, SiO2 and combinations thereof.
Substrates for use with the embodiments of the invention can be any suitable substrate. In detailed embodiments, the substrate is a rigid, discrete, generally planar substrate. As used in this specification and the appended claims, the term “discrete” when referring to a substrate means that the substrate has a fixed dimension. The substrate of specific embodiments is a semiconductor wafer, such as a 200 mm or 300 mm or 450 mm diameter silicon wafer.
As used in this specification and the appended claims, the terms “reactive gas”, “reactive precursor”, “first precursor”, “second precursor” and the like, refer to gases and gaseous species capable of reacting with a substrate surface or a layer on the substrate surface.
In some embodiments, one or more layers may be formed during a plasma enhanced atomic layer deposition (PEALD) process. In some processes, the use of plasma provides sufficient energy to promote a species into the excited state where surface reactions become favorable and likely. Introducing the plasma into the process can be continuous or pulsed. In some embodiments, sequential pulses of precursors (or reactive gases) and plasma are used to process a layer. In some embodiments, the reagents may be ionized either locally (i.e., within the processing area) or remotely (i.e., outside the processing area). In some embodiments, remote ionization can occur upstream of the deposition chamber such that ions or other energetic or light emitting species are not in direct contact with the depositing film. In some PEALD processes, the plasma is generated external from the processing chamber, such as by a remote plasma generator system. The plasma may be generated via any suitable plasma generation process or technique known to those skilled in the art. For example, plasma may be generated by one or more of a microwave (MW) frequency generator or a radio frequency (RF) generator. The frequency of the plasma may be tuned depending on the specific reactive species being used. Suitable frequencies include, but are not limited to, 2 MHz, 13.56 MHz, 40 MHz, 60 MHz and 100 MHz. Although plasmas may be used during the deposition processes disclosed herein, it should be noted that plasmas may not be required. Indeed, other embodiments relate to deposition processes under very mild conditions without plasma.
According to one or more embodiments, the substrate is subjected to processing prior to and/or after forming the layer. This processing can be performed in the same chamber or in one or more separate processing chambers. In some embodiments, the substrate is moved from the first chamber to a separate, second chamber for further processing. The substrate can be moved directly from the first chamber to the separate processing chamber, or it can be moved from the first chamber to one or more transfer chambers, and then moved to the desired separate processing chamber. Accordingly, the processing apparatus may comprise multiple chambers in communication with a transfer station. An apparatus of this sort may be referred to as a “cluster tool” or “clustered system”, and the like.
Generally, a cluster tool is a modular system comprising multiple chambers which perform various functions including substrate center-finding and orientation, degassing, annealing, deposition and/or etching. According to one or more embodiments, a cluster tool includes at least a first chamber and a central transfer chamber. The central transfer chamber may house a robot that can shuttle substrates between and among processing chambers and load lock chambers. The transfer chamber is typically maintained at a vacuum condition and provides an intermediate stage for shuttling substrates from one chamber to another and/or to a load lock chamber positioned at a front end of the cluster tool. Two well-known cluster tools which may be adapted for the present invention are the Centura® and the Endura®, both available from Applied Materials, Inc., of Santa Clara, Calif. The details of one such staged-vacuum substrate processing apparatus are disclosed in U.S. Pat. No. 5,186,718, entitled “Staged-Vacuum Wafer Processing Apparatus and Method,” Tepman et al., issued on Feb. 16, 1993. However, the exact arrangement and combination of chambers may be altered for purposes of performing specific steps of a process as described herein. Other processing chambers which may be used include, but are not limited to, cyclical layer deposition (CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etch, pre-clean, chemical clean, thermal treatment such as RTP, plasma nitridation, degas, orientation, hydroxylation and other substrate processes. By carrying out processes in a chamber on a cluster tool, surface contamination of the substrate with atmospheric impurities can be avoided without oxidation prior to depositing a subsequent film.
According to one or more embodiments, the substrate is continuously under vacuum or “load lock” conditions, and is not exposed to ambient air when being moved from one chamber to the next. The transfer chambers are thus under vacuum and are “pumped down” under vacuum pressure. Inert gases may be present in the processing chambers or the transfer chambers. In some embodiments, an inert gas is used as a purge gas to remove some or all of the reactants after forming the silicon layer on the surface of the substrate. According to one or more embodiments, a purge gas is injected at the exit of the deposition chamber to prevent reactants from moving from the deposition chamber to the transfer chamber and/or additional processing chamber. Thus, the flow of inert gas forms a curtain at the exit of the chamber.
The substrate can also be stationary or rotated during processing. A rotating substrate can be rotated continuously or in discreet steps. For example, a substrate may be rotated throughout the entire process, or the substrate can be rotated by a small amount between exposure to different reactive or purge gases. Rotating the substrate during processing (either continuously or in steps) may help produce a more uniform deposition or etch by minimizing the effect of, for example, local variability in gas flow geometries.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US14/33604 | 4/10/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61812507 | Apr 2013 | US |
