Patent Application
20100075488
Embodiments of the invention relate to deposition and etch reactions on a semiconductor substrate, such as an epitaxial deposition process or other chemical vapor deposition process. More specifically, embodiments of the invention relate to an apparatus for manipulating a substrate to perform such processes.
Epitaxial growth of silicon and/or germanium-containing films has become increasingly important due to new applications for advanced logic and DRAM devices, among other devices. As smaller transistors are manufactured, ultra shallow source/drain junctions for sub-100 nm CMOS (complementary metal-oxide semiconductor) devices, such as silicon-containing MOSFET (metal oxide semiconductor field effect transistor) devices, are becoming more challenging to produce. Silicon based materials may be used in device creation for MOSFET devices. For example, in a PMOS application, the film in a recessed area of the transistor is usually silicon-germanium, and for a NMOS application, the film in the recessed area may be SiC. Silicon-germanium is advantageously used to implant more boron than silicon alone to reduce junction resistivity, which improves device performance, for example, the silicon-germanium interface with the silicide layer at the substrate surface has a lower Schottky barrier than the silicon interface with silicon-germanium.
Selective silicon-epitaxial (Si-epitaxial) deposition and silicon-germanium-epitaxial deposition permits growth of epilayers on silicon (Si) moats with no growth on dielectric areas. Selective epitaxy can be used in semiconductor devices, such as within source/drains, source/drain extensions, contact plugs, and base layer deposition of bipolar devices. Additionally, selective epitaxy permits near complete dopant activation with in-situ doping, so that the post annealing process may be omitted. Therefore, junction depth can be defined accurately by silicon etching and selective epitaxy. Improved junction depth also produces compressive stress. One example of the use of silicon containing materials in device creation is for MOSFET devices.
As in most processes, efficient and non-destructive manipulation of substrates in epitaxial processes is desired. For example, in many epitaxial processes, a substrate is rotated to ensure uniform deposition. Additionally, substrates are generally raised and lowered in preparation for processing, and also thereafter. Because handling substrates can generate particles inside processing chambers, it is desired that such handling be relatively gentle. Control of substrate positioning during processing may also impact the quality of deposited films. Thus, there is a need for an apparatus capable of depositing an epitaxial film on a substrate while positioning the substrate most desirably and handling the substrate without generating particles.
Embodiments of the invention generally provide an apparatus for processing a substrate, comprising a processing chamber comprising a lid, a floor, and a wall, a substrate support disposed within the processing chamber and having a lift shaft that penetrates the floor, and a lift mechanism configured to translate the substrate vertically within the chamber, operate lift pins to lift the substrate above the substrate support, and rotate the substrate while translating it within the chamber. Some embodiments feature a magnetically actuated rotor attached to the lift shaft, with a magnetic actuator coupled to a motor to provide rotation.
Other embodiments provide a process chamber for processing a semiconductor substrate, comprising a sidewall, top, and bottom defining an internal volume of the process chamber, a plurality of edge rings disposed along the sidewall, each edge ring defining a boundary of at least one processing zone in the internal volume of the process chamber, a substrate support disposed in the internal volume of the chamber and configured to rotate about a central axis of the substrate support while moving in a direction parallel to the central axis, and a gas conduit coupled to each processing zone of the processing chamber.
Other embodiments provide a method of processing a semiconductor substrate, comprising positioning the substrate on a substrate support in the processing chamber, rotating the substrate on the substrate support, and moving the substrate along an axis of rotation while rotating the substrate.
So that the manner in which the above-recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of 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 disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
Embodiments of the invention generally provide an apparatus for depositing a film on a substrate.
A substrate support 117 is adapted to receive a substrate 114 that is transferred to the processing volume 118 on a surface 116 of the substrate support 117. The substrate support 117 may be made of a ceramic material or a graphite material coated with a silicon material, such as silicon carbide, or other process resistant material. Reactive species from precursor reactant materials are applied to the exposed surface of the substrate 114, and byproducts may be subsequently removed from the surface of the substrate 114. Heating of the substrate 114 and/or the processing volume 118 may be provided by radiation sources, such as upper lamp modules 110A and lower lamp modules 110B. The substrate support 117 may rotate about a central axis 102 of the substrate support while moving in a direction parallel to the central axis 102 by displacement of support shaft 140. Lift pins 170 are provided that penetrate the surface 116 of the substrate support 117 and lift the substrate 114 above the substrate support 117 for transportation into and out of the processing chamber. The lift pins 170 are coupled to the support shaft 140 by a lift pin collar 174.
In one embodiment, the upper lamp modules 110A and lower lamp modules 110B are infrared (IR) lamps. Non-thermal energy or radiation from lamp modules 110A and 110B travels through upper quartz window 104 of upper quartz chamber 105, and through the lower quartz portion 103 of lower quartz chamber 124. Cooling gases for upper quartz chamber 105, if needed, enter through an inlet 112 and exit through an outlet 113. Precursor reactant materials, as well as diluent, purge and vent gases for the chamber 100, enter through gas distribution assembly 150 and exit through outlet 138.
The low wavelength radiation in the processing volume 118, which is used to energize reactive species and assist in adsorption of reactants and desorption of process byproducts from the surface 116 of substrate 114, typically ranges from about 0.8 μm to about 1.2 μm, for example, between about 0.95 μm to about 1.05 μm, with combinations of various wavelengths being provided, depending, for example, on the composition of the film which is being epitaxially grown. In another embodiment, the lamp modules 110A and 110B may be ultraviolet (UV) light sources. In one embodiment, the UV light source, is an excimer lamp. In another embodiment, UV light sources may be used in combination with IR light sources in one or both of the upper quartz chamber 105 and lower quartz chamber 124. An example of UV radiation sources used in combination with IR radiation sources can be found in U.S. patent application Ser. No. 10/866,471, filed Jun. 10, 2004, which published on Dec. 15, 2005, as United States patent publication No. 2005/0277272, which is incorporated by reference in its entirety.
The component gases enter the processing volume 118 via gas distribution assembly 150 through port 158, which may have a portal liner 154, and through passage 152N. The portal liner 154 may be a nozzle in some embodiments. The gas distribution assembly 150 includes a tubular heating element 156, disposed in a conduit 224N, that heats the processes gases to a desired temperature before they enter the processing chamber. Gas flows from the gas distribution assembly 150 and exits through port 138 as shown generally at 122. Combinations of component gases, which are used to clean/passivate a substrate surface, or to form the silicon and/or germanium-containing film that is being epitaxially grown, are typically mixed prior to entry into the processing volume. The overall pressure in the processing volume 118 may be adjusted by a valve (not shown) on the outlet port 138. At least a portion of the interior surface of the processing volume 118 is covered by a liner 131. In one embodiment, the liner 131 comprises a quartz material that is opaque. In this manner, the chamber wall is insulated from the heat in the processing volume 118.
The temperature of surfaces in the processing volume 118 may be controlled within a temperature range of about 200° C. to about 600° C., or greater, by the flow of a cooling gas, which enters through a port 112 and exits through port 113, in combination with radiation from upper lamp modules 110A positioned above upper quartz window 104. The temperature in the lower quartz chamber 124 may be controlled within a temperature range of about 200° C. to about 600° C. or greater, by adjusting the speed of a blower unit which is not shown, and by radiation from the lower lamp modules 1108 disposed below lower quartz chamber 124. The pressure in the processing volume 118 may be between about 0.1 Torr to about 600 Torr, such as between about 5 Torr to about 30 Torr.
The temperature on a surface of the substrate 114 may be controlled by power adjustment to the lower lamp modules 1108 in lower quartz chamber 124, or by power adjustment to both the upper lamp modules 110A overlying upper quartz chamber 105, and the lower lamp modules 1108 in lower quartz chamber 124. The power density in the processing volume 118 may be between about 40 W/cm2 to about 400 W/cm2, such as about 80 W/cm2 to about 120 W/cm2.
In one aspect, the gas distribution assembly 150 is disposed normal to, or in a radial direction 106 relative to, the longitudinal axis 102 of the chamber 100 or substrate 114. In this orientation, the gas distribution assembly 150 is adapted to flow process gases in a radial direction 106 across, or parallel to, a surface of the substrate 114. In one application, the process gases are preheated at the point of introduction to the chamber 100 to initiate preheating of the gases prior to introduction to the processing volume 118, and/or to break specific bonds in the gases. In this manner, surface reaction kinetics may be modified independently from the thermal temperature of the substrate 114.
The lift assembly 250 comprises a lift motor 252 coupled to a lift actuator 256. The lift actuator 256 may be a screw-type actuator rotatably coupled to the lift motor 252 in some embodiments. The lift actuator 256 is coupled to a lift coupling 258. The lift coupling 258 couples to components of the support shaft assembly 202, as described in further detail below. In embodiments wherein the lift actuator 256 is a screw-type actuator, the lift coupling 258 may be a threaded collar. In embodiments featuring a threaded lift collar and screw-type lift actuator, the lift collar rides along a longitudinal direction of the lift actuator by virtue of threads on the lift actuator that mate with threads on the lift collar. As the motor turns the lift actuator, threads on the lift actuator mated to threads on the lift collar force the lift collar to move along the lift actuator in a longitudinal direction. In alternate embodiments, the lift coupling 258 may be a glide coupling that mates with a rail or an unthreaded collar that slides along a rod, either of which may be actuated by a linear actuator coupled to the lift motor 252.
In embodiments wherein the lift actuator 256 rotates, the lift coupling 258 may be prevented from rotating by a compression bracket 260, which is coupled to a compression seat 262 by fasteners (not shown). Application of the compression bracket 260 and compression seat 262 to the lift coupling 258 results in a frictional force on the lift coupling 258 that prevents rotation. In another embodiment, the lift coupling 258 may be prevented from rotating by providing a guide rod substantially parallel to the lift actuator 256 and passing through a portion of the lift coupling 258. In such an embodiment, the lift coupling 258 may ride along the guide rod, which would prevent rotation of the lift coupling 258 with the lift actuator 256. In other alternate embodiments, a threaded lift collar may be prevented from rotating in other ways, such as by providing a ridge or tab on an outside surface of the lift coupling 258 that can mate with a groove in a member, such as a rail, fastened to the motor 252.
The support shaft assembly 202 comprises the support shaft 140, a rotation assembly 240, a chamber coupling 220, an upper bellows 232, and a lower bellows 234. The support shaft 140 is coupled with the surface 116 of the substrate support 117 at a first end 120 of the support shaft 140 (
The rotation assembly 240 is coupled with the lift assembly 250 by a first lift member 206. The first lift member 206 comprises a first extension 208 that couples the rotation assembly 240 to the lift coupling 258. The first extension 208 extends through the support bracket 204 and couples to the lift coupling 258, or the compression seat 262, or both. As the lift coupling 258 moves, the first lift member 206 moves the support shaft assembly 202 accordingly. The first lift member 206 may also comprise a support plate 210 in some embodiments. The support plate 210 generally constrains motion of the support shaft assembly 202 to one dimension by ridges or extensions (not shown) that mate with channels or openings in the support bracket 204.
The support shaft assembly 202 further comprises a second lift member 216. The second lift member 216 is coupled to the lift assembly 250 by a second extension 218 and a resilient member 266. The second extension 218 also couples the support mechanism 200 to a lift pin assembly, such as the lift pin collar 174 and lift pins 170 of
The second lift member 216 moves with the support shaft assembly 202 by virtue of the lower bellows 234. Movement of the second lift member 216 is constrained, however, by features of the lift assembly 250. As the second lift member 216 moves toward the processing chamber, a restorative force develops in the resilient member 266 tending to urge the second lift member 216 away from the processing chamber. Additionally, an upper stop 268 is positioned at the desired location with respect to any feature fastened unmovably to the lift assembly 250, such as the support bracket 204 or the motor mount 264. When the second lift member 216 impinges the upper stop 268, movement of the second lift member 216 toward the processing chamber stops.
Features of the lift assembly 250 also constrain withdrawal of the second lift member 216. As the second lift member 216 moves away from the processing chamber, a restorative force develops in the resilient member 266 tending to urge the second lift member toward the processing chamber. Additionally, a lower stop 270 is also provided to constrain withdrawal of the second lift member 216. In the embodiment of
As the support shaft 140 is lowered by the lift motor 252, the second lift member 216 initially travels with the support shaft 140 by virtue of the lower bellows 234, thus lowering the lift pins 170 (
When the support shaft 140 is raised by the lift motor 252, the restorative force of the resilient member 266, tension in the lower bellows 234 initially overcomes the restorative force in the resilient member 266, holding the second extension 218 against the lower stop 270 and keeping the lift pins 170 (
When the second extension 218 reaches the upper stop 268, the second lift member 216 and the lift pins 170 (
Because the support shaft 140 travels into the processing chamber, and the processing chamber is generally maintained at low pressure, the support shaft 140 is generally maintained in a low pressure environment to avoid contamination of the reaction zone inside the processing chamber. The upper bellows 232 provides a low-pressure enclosure between the second lift member 216 and the chamber coupling 220. The lower bellows 234 provides a low-pressure enclosure between the second lift member 216 and the first lift member 206. In this way, the support shaft 140 may be housed in an environment maintained at the same pressure as the processing chamber.
A sensor plate 272 may coupled to the lift assembly 250, for example by fastening to the support bracket 204. The sensor plate 272 provides a location for mounting sensors that may be used to control operation of the lift mechanism. The embodiment of
It should be noted that the sensor 268A, functioning as a rotation interlock sensor, enables rotation of the substrate 114 (
The support mechanism 200, with concurrent axial and rotational movement, also enables processing a substrate at different levels in the processing chamber, or in different processing zones of the processing chamber.
The chamber 300 further comprises one or more edge rings 348 that define processing zones within the internal volume 342. The edge rings 348 may comprise up to five edge rings, for example between one and five edge rings. In some embodiments, a chamber may have a plurality of edge rings. In the embodiment of
Each edge ring defines a boundary of at least one processing zone, as well as an opening in which the substrate support 304 is positioned to define a lower of the processing zone. For example, a first processing zone is defined by a first edge ring and a second edge ring above the first edge ring. The lower boundary of the first processing zone is defined by the first edge ring and the upper boundary of the first processing zone is defined by the second edge ring, which may also define the lower boundary of a second processing zone above the first processing zone. When the substrate support is positioned proximate to the first edge ring, in an opening defined by the first edge ring, it provides a floor for the first processing zone while a substrate is being processed therein.
The plurality of edge rings 348 comprises one edge ring 320 that extends over a shoulder 350 of the substrate support 304, which will usually be the uppermost edge ring of the chamber. The other edge rings, for example the edge rings 316 and 318 of
As the substrate support is positioned proximate to the edge rings 316 and 318, first and second gaps, 352 and 354 respectively, are defined by inner radii of the edge rings 316 and 318 and an edge portion 356 of the substrate support 304. For example the first edge ring 316 defines the gap 352 between the inner radius of the first edge ring 316 and the edge portion 356 of the substrate support 304 when the substrate support is positioned proximate the first edge ring 316, and the second edge ring 318 defines the gap 354 between the inner radius of the second edge ring 318 and the edge portion 356 of the substrate support 304 when the substrate support is positioned proximate the second edge ring 316.
The gaps 352 and 354, or all such gaps between edge rings and the substrate support 304 in embodiments featuring more or less than three edge rings, may vary in width depending on the geometry of the chamber and the desired processing characteristics. In most embodiments, the gaps will each have a width “W” between about 0.5% and about 75% of the distance “D” between the edge portion 356 of the substrate support 304 and the chamber enclosure 302. In a chamber adapted to process 300 mm substrates, the gaps may each have a width between about 1 mm and about 100 mm. In some embodiments, the gaps may all have the same width W, while in other embodiments, such as that shown in
Gas is provided to the various processing zones defined by the edge rings through a plurality of gas conduits, each of which is coupled to a processing zone. In
Substrates are provided to, and removed from, the chamber through opening 310 below the lowermost processing zone. As discussed above in connection with
In operation, the substrate support is positioned proximate to one of the edge rings, such as the edge ring 318. Gas is provided through the conduit serving the processing zone defined by the edge ring 318 and the substrate support 304, which in the
After processing in a first processing zone, the substrate support 304 is moved to a second processing zone by moving along an axis of the substrate support 304. Rotation of the substrate support is maintained during movement between processing zones to minimize non-productive time. Processing conditions in the second processing zone may be established prior to moving the substrate support into position so that processing commences immediately.
A substrate is disposed on a substrate support in a processing chamber at 410. A processing chamber such as the chamber 300 of
The substrate is positioned at a first processing zone inside the process chamber at 420. The substrate support is moved from a loading or unloading position at 410 to the first processing zone. In some embodiments, the first processing zone is defined by a first divider, which may be a first plurality of dividers, that define the first processing zone. As the substrate support moves to a position proximate the first divider, the substrate disposed on the substrate support enters the first processing zone.
At 430, a first processing cycle is performed on the substrate in the first processing zone. A first gas is provided to the first processing zone, and energy may be added using the substrate support or another energy source positioned inside or outside the processing chamber. In one embodiment, a heat source may be positioned above or below the chamber, or both, to heat substrates during processing. In one embodiment, processing conditions such as substrate temperature and pressure above the substrate are achieved at the time the substrate reaches the first processing zone. In other embodiments, the desired processing conditions may be established in the first processing zone before positioning the substrate support. In either embodiment, processing may begin immediately when the substrate enters the first processing zone.
At 440, the substrate is positioned at a second processing zone by moving the substrate support. Similar to the first processing zone, the second processing zone may be defined by a second divider to minimize cross flow of gases from one processing zone to another. A gas curtain may also be provided between the processing zones. The gas curtain may also be useful for performing a cooling operation between two deposition or etch operations. The gas curtain may also be useful for purging reactants from the substrate surface between operations.
At 450, a second processing cycle is performed on the substrate in the second processing zone. A second gas is provided to the second processing zone. As with the first processing zone, energy may be added to the second processing zone using the same energy source or a different energy source. For example, if the first processing zone is proximate a first energy source, and the second processing zone proximate a second energy source, the first energy source may be used during the first processing cycle and the second energy source during the second processing cycle.
At 460, the substrate is rotated during processing, and the rotation is maintained while processing and positioning the substrate. For process cycles wherein rotation is not advantageous, rotation may be stopped and then restarted for subsequent process cycles in which rotation is desired. Rotation is generally maintained while moving the substrate between processing zones such that processing may start immediately when the substrate enters the next processing zone. No time is spent waiting for rotation to achieve the desired RPM.
In an exemplary embodiment, a chamber having three processing zones similar to the chamber 300 of
In another exemplary embodiment, a sequential deposition and etch process may be performed in such a chamber by establishing process conditions for the two processes in adjacent processing zones and moving the substrate between them in a prescribed manner. It should be noted that a processing chamber having three or more processing zones may be used to perform long, complex processes involving many more than three operations by adjusting processing conditions in idle processing zones. For example, after performing three operations in three different processing zones, processing conditions in the idle processing zones may be changed to perform a fourth, fifth, or further operations on the substrate.
In some embodiments, the processing conditions established in a processing zone may involve activated precursors. In one embodiment, remotely activated precursors may be provided to one or more processing zones. Remotely activated precursors may be provided to one processing zone while non-activated, or even inert, precursors are provided to an adjacent processing zone. In one embodiment, a processing zone, for example the uppermost or lowermost processing zone, may be positioned adjacent to an inductive source for producing an inductively coupled plasma in the uppermost or lowermost processing zone. The inductive source may be operated in a way that couples energy into the desired processing zone at a power level selected to drive a reaction in the processing zone while declining to a level below that required to drive a reaction in an adjacent processing zone. Such conditions may be useful for performing a plasma deposition, plasma etch, or plasma cleaning operation as part of a larger sequence of operations. If necessary, an electrical bias may be coupled to the substrate support, if desired for certain operations in certain processing zones.
While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.
This application claims benefit of U.S. Provisional Patent Application Ser. No. 61/098,699 (APPM/12952L/FEP/EPI/PJT) filed Sep. 19, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61098699 | Sep 2008 | US |
