Patent Application
20060046412
The present invention relates to sequential thin film processing.
The fabrication of modem semiconductor workpiece structures has traditionally relied on plasma processing in a variety of operations such as etching and deposition. Plasma etching involves using chemically active atoms or energetic ions to remove material from a substrate. Deposition techniques employing plasma include Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD) or sputtering. PVD uses a high vacuum apparatus and generated plasma that sputters atoms or clusters of atoms toward the surface of the wafer substrates. PVD is a line of sight deposition process that is more difficult to achieve conformal film deposition over complex topography such as deposition of a thin and uniform liner or barrier layer over the small trench or via of 0.13 μm or less, especially with high aspect ratio greater than 4:1. Plasma generation methods include parallel plate plasma, inductive coupled plasma (ICP), remote plasma, microwave plasma. In parallel plate plasma, a power source is applied across two parallel plates to create an electric field which will ionize the gas to generate the plasma. The plasma is confined between the parallel plates where the electric field is strongest, and there is significant plasma bombardment due to the presence of the electric field. In inductive coupled plasma, a power source is applied to a coil to create a magnetic field which will ionize the gas to generate the plasma. A non-conducting window such as ceramic plate could be used to separate the plasma source from the plasma. Care should be taken so that no metal is deposited on the non-conducting window, otherwise the deposited metal will block the magnetic field, and the plasma will be extinguished. This is the reason why inductive coupled plasma was not used for metal deposition. Typical parallel plate plasma and inductive coupled plasma use radio frequency (RF) power sources. In remote plasma, a plasma is generated elsewhere and then being brought to the process chamber. In microwave plasma, the plasma uses microwave frequency (MW) power source. Microwave plasma tends to be remote plasma, and is brought to the process chamber using microwave guide.
In CVD processing, a gas or vapor mixture is flowed over the wafer surface that is kept at an elevated temperature. Reactions then take place at the hot surface where deposition takes place. Temperature of the wafer surface is an important factor in CVD deposition, as it depends on the chemistry of the precursor for deposition and affects the uniformity of deposition over the large wafer surface. CVD typically requires high temperature for deposition which may not be compatible with other processes in the semiconductor process. CVD at lower temperature tends to produce low quality films in terms of uniformity and impurities.
In a deposition technology, similar to the CVD technique, known as atomic layer deposition (ALD), various gases are injected into the chamber for as short as 100-500 milliseconds in alternating sequences. For example, a first gas is delivered into the chamber for about 500 milliseconds and the substrate is heated, then the first gas (heat optional) is turned off. The residue from the first gas is then evacuated. Another gas is delivered into the chamber for another 500 milliseconds (heat optional). The residue from this gas is also evacuated before the next gas is delivered for about 500 milliseconds (and optionally heated). This sequence is done until all gases have been cycled through the chamber, each gas sequence typically forms a monolayer which is highly conformal. ALD technology thus pulses gas injection and heating sequences that are between 100 and 500 milliseconds. This approach has a high dissociation energy requirement to break the bonds in the various precursor gases such as silane and oxygen and thus requires the substrate to be heated to a high temperature, for example in the order of 600-800° C. for silane and oxygen processes.
ALD also uses radical generators, such as plasma generators, to increase the reactivity of the second gas and effectively the reaction between the first and the second gases at the substrate. U.S. Pat. No. 5,916,365 to Sherman entitled “Sequential Chemical Vapor Deposition” provides for sequential chemical vapor deposition by employing a reactor operated at low pressure, a pump to remove excess reactants, and a line to introduce gas into the reactor through a valve. Sherman exposes the part to a gaseous first reactant, including a non-semiconductor element of the thin film to be formed, wherein the first reactant adsorbs on the part. The Sherman process produces sub-monolayer per gas injection due to adsorption. The first reactant forms a monolayer on the part to be coated (after multiple cycles), while the second reactant passes through a radical generator which partially decomposes or activates the second reactant into a gaseous radical before it impinges on the monolayer. This second reactant does not necessarily form a monolayer but is available to react with the deposited monolayer. A pump removes the excess second reactant and reaction products completing the process cycle. The process cycle can be repeated to grow the desired thickness of film.
There is other applications using plasma in ALD process. U.S. Pat. No. 6,200,893 to Sneh entitled “Radical-assisted sequential CVD” discusses a method for CVD deposition on a substrate wherein radical species are used in alternate steps to depositions from a molecular precursor to treat the material deposited from the molecular precursor and to prepare the substrate surface with a reactive chemical in preparation for the next molecular precursor step. By repetitive cycles a composite integrated film is produced. In a preferred embodiment the depositions from the molecular precursor are metals, and the radicals in the alternate steps are used to remove the ligands left from the metal precursor reactions, and to oxidize or nitride the metal surface in subsequent layers.
In one embodiment taught by Sneh, a metal is deposited on a substrate surface in a deposition chamber by (a) depositing a monolayer of metal on the substrate surface by flowing a molecular precursor gas or vapor bearing the metal over a surface of the substrate, the surface saturated by a first reactive species with which the precursor will react by depositing the metal and forming reaction product, leaving a metal surface covered with ligands from the metal precursor and therefore not further reactive with the precursor; (b) terminating flow of the precursor gas or vapor; (c) purging the precursor with an inert gas; (d) flowing at least one radical species into the chamber and over the surface, the radical species is highly reactive with the surface ligands of the metal precursor layer and eliminates the ligands as reaction product, and saturates the surface, providing the first reactive species; and (e) repeating the steps in order until a metallic film of desired thickness results.
In another Sneh aspect, a metal nitride is deposited on a substrate surface in a deposition chamber by (a) depositing a monolayer of metal on the substrate surface by flowing a metal precursor gas or vapor bearing the metal over a surface of the substrate, the surface saturated by a first reactive species with which the precursor will react by depositing the metal and forming reaction product, leaving a metal surface covered with ligands from the metal precursor and therefore not further reactive with the precursor; (b) terminating flow of the precursor gas or vapor; (c) purging the precursor with inert gas; (d) flowing a first radical species into the chamber and over the surface, the atomic species highly reactive with the surface ligands of the metal precursor layer and eliminating the ligands as reaction product and also saturating the surface; (e) flowing radical nitrogen into the chamber to combine with the metal monolayer deposited in step (a), forming a nitride of the metal; (f) flowing a third radical species into the chamber terminating the surface with the first reactive species in preparation for a next metal deposition step; and (g) repeating the steps in order until a composite film of desired thickness results.
The Sneh embodiments thus deposit monolayers, one at a time. This process is relatively time-consuming as a thick film is desired.
Another application relating to sequential deposition is nanolayer thick film deposition (“NLD”), U.S. Pat. No. 6,756,318 issued on Jun. 29, 2004 by the same inventors, Tue Nguyen et al., NLD is a process of depositing a thin film by chemical vapor deposition, including the steps of evacuating a chamber of gases, exposing a workpiece to a gaseous first reactant, wherein the first reactant deposits on the workpiece to form the thin film, then evacuating the chamber of gases, and exposing the workpiece, coated with the first reactant, to a gaseous second reactant under plasma, wherein the thin film deposited by the first reactant is treated to form the same materials or a different material. U.S. Pat. No. 6,756,318 is hereby incorporated by reference.
In comparison with CVD, atomic layer deposition (ALD or ALCVD) is a modified CVD process that is temperature sensitive and flux independent. ALD is based on self-limiting surface reaction. ALD provides a uniform deposition over complex topography and temperature independent since the gases are adsorbed onto the surface at lower temperature than CVD because it is in adsorption regime.
As discussed in Sherman and Sneh, the ALD process includes cycles of flowing gas reactant into the chamber, adsorbing one sub-monolayer onto the wafer surface, purging the gas reactant, flowing a second gas reactant into the chamber, and reacting the second gas reactant with the first gas reactant to form a monolayer on the wafer substrate. Thick film is achieved by deposition of multiple cycles.
Precise thickness can be controlled by number of cycles since monolayer is deposited per cycle. However, the conventional ALD method is slow in depositing films such as those around 100 angstroms in thickness. Growth rate of ALD TiN for example was reported at 0.2 angstrom/cycle, which is typical of metal nitrides from corresponding chlorides and NH3.
The throughput in workpiece fabrication for a conventional ALD system is slow. Even if the chamber is designed with minimal volume, the throughput is still slow due to the large number of cycles required to achieve the thickness. The pump/purge cycle between gases is very time consuming, especially with liquid or solid vapors. Conventional ALD is a slower process than CVD with a rate of deposition almost 10 times as slow as CVD deposition. The process is also chemical dependent to have the proper self-limiting surface reaction for deposition. To improve the throughput, a batch system has been developed to process many wafers at the same time.
As with other sequential processing methods, the precursor gases or vapors are introduced sequentially with a pump/purge step in between to ensure the complete removal of the precursor. This pump/purge step does not contribute to the film process, therefore it is desirable if one would be able to remove this step from the processing sequence.
Accordingly, a two-compartment chamber apparatus for sequential and isolated processing method is disclosed.
In a co-pending application, U.S. patent application Ser. No. 10/213,003, now U.S. Pat. No. 6,858,085, by the same inventors, Tue Nguyen et al., entitled “Two-Compartment Chamber for Sequential Processing,” a two-compartment apparatus is disclosed to perform the sequential processing of a workpiece without the pump/purge step. The processing chamber comprises two compartments: the first compartment to process the workpiece using first precursors or reactants and the second compartment to process the workpiece using second precursors or reactants. These two compartments are separated by an internal pathway to allow the passage of the workpiece from one compartment to the other compartment. Instead of a pump/purge step to separate the precursors in the one-compartment chamber as in prior art methods, the present invention two-compartment chamber apparatus moves the workpiece between the compartments. The moving mechanism comprises a workpiece mover for supporting the workpiece during the movement. The moving mechanism further comprises an actuator, such as a motor, coupled to the workpiece mover to move the workpiece from one compartment to the other compartment. The moving mechanism has two end positions, at each end position, the workpiece is located in each compartment. There are two pathway doors coupled at the two ends of the workpiece mover. The pathway doors are coupled to the workpiece mover in such a way so that one of the pathway doors closes the internal pathway between the two compartments in each end position of the moving mechanism. As such, the pathway doors ensure the isolation of the compartments for processing and to prevent cross contamination from the other compartment. Since the two pathway doors are coupled to the workpiece mover, one of the pathway doors automatically closes the pathway between the compartments after the workpiece has moved completely to an end position. U.S. Pat. No. 6,858,085 is hereby incorporated by reference.
A typical sequential processing comprises the following steps:
During the workpiece transfer, the pathway door is open and the two compartments are connected and a small amount of cross contamination occurs. Depending on the process requirements, a short pumping time after the completion of the workpiece transfer might be needed to remove the cross contamination. In any case, the short pumping time is shorter than the pump/purge step of the prior art. With two-compartment chamber, compartment cleaning can be selective. For example, if one compartment is used for deposition and another for treatment, only the deposition compartment needs to be cleaned.
The processing of the workpiece can be a deposition of a thin film, or an adsorption of a sub-monolayer of a plurality of precursors or reactants, or an etching of a thin layer, or a reaction, with or without an exciting source such as a plasma source, of a plurality of precursors or reactants onto the existing layers on the workpiece.
Implementations of the above aspect may include one or more of the following.
The two pathway doors coupled to the workpiece mover can be equal or smaller than the internal pathway opening. This way the workpiece mover can reside completely in one of the compartment, and the pathway door can go across the internal pathway. The advantage of this implementation is the simple design and the workpiece mover can travel widely. But the disadvantage is that the degree of isolation can be reduced if the gap between the pathway and the pathway door is too large. If the gap is too small, there can be friction, resulting in wear and tear, and possible particle generation.
The two pathway doors coupled to the workpiece mover can be larger than the internal pathway opening. Since the pathway doors are larger than the opening, the doors cannot travel across the internal pathway. Therefore the workpiece mover is positioned so that one pathway door resides within one compartment and the other pathway doors resides within the other compartment. Large pathway doors can provide better isolation for the two compartments. Better isolation can be achieved with the addition of o-ring so that the internal pathway closing is metal to o-ring seal instead of metal to metal seal.
A workpiece mover heater can be coupled to the workpiece mover. The workpiece mover heater is capable of heating the workpiece to an elevated temperature. Many processing techniques require that the workpiece be heated, from room temperature to around 400.degree. in the cases of plasma processing, or 800° C. in the case of high temperature CVD, or 1200° C. as in the case of rapid thermal processing. The workpiece heater can provide the high temperature needed for these selected processing requirements. By coupling to the workpiece mover, the workpiece mover heater moves with the workpiece mover, therefore there is only one workpiece mover heater for the two-compartment chamber.
The movement of the workpiece mover from one compartment to the other compartment can be a rotational movement. The angle from the two pathway doors can be anywhere from a few degrees to a maximum of 180 apart, with roughly 90-100° as the desired angles to minimize the footprint of the process chamber.
The movement of the workpiece mover from one compartment to the other compartment can be a linear movement. The linear movement further comprises a linear guide coupled to the motor to guide the movement of the workpiece mover. The two pathway doors are positioned at the two ends of the movement.
The apparatus can further comprises a second actuator, such as a motor, coupled to a second linear guide to move the workpiece mover in a vertical direction somewhat perpendicular to the movement from one compartment to the other compartment. The vertical movement is designed to clear the workpiece mover of any obstacles during the compartment to compartment transfer.
The apparatus can further comprises an external pathway coupled to one of the compartment. The external pathway is designed to allow the passage of the workpiece to the outside of the workpiece processing chamber, and from the outside to the workpiece processing chamber. The external pathway can comprise an external door to isolate the process chamber from the outside ambient.
The apparatus can further comprises a plurality of workpiece heaters coupled to the processing chamber. There can be only one workpiece heater in only one compartment, or there can be two workpiece heaters, one for each compartment. The workpiece heaters are capable of heating the workpiece to an elevated temperature. The two workpiece heaters can be independent, so that one can achieve different temperature than the other. The workpiece heaters are a part of the process requirements. Some processes require that the workpiece be heated to an elevated temperature, while other processes can run at room temperature and other processes need to run below room temperature. The workpiece heater can be radiative heater such as a lamp, or resistive heater. The workpiece heater can comprises a third actuator, such as a motor, coupled to a linear guide to move the workpiece heater in a vertical direction somewhat perpendicular to the compartment to compartment movement. This vertical movement is designed to clear the workpiece mover of any obstacles during the compartment to compartment transfer. The linear guide can be coupled to the workpiece heater, and the workpiece heater can move up and down to clear the path for the workpiece mover. The linear guide can be coupled to the workpiece mover, and the workpiece mover can move up and down to clear the workpiece heater during the transfer.
The apparatus can further comprises a plurality of delivery systems coupled to the processing chamber. There can be only one delivery system in only one compartment, or there can be two delivery systems, one for each compartment. The delivery systems are capable of delivering a plurality of precursors or reactants onto the workpiece. The delivery systems are a part of the process requirements. The delivery system can be a liquid precursor delivery system to deliver a plurality of precursor vapors from a plurality of liquid precursor sources. The delivery system can be a solid precursor delivery system to deliver a plurality of precursor vapors from a plurality of solid precursor sources. The delivery system can be a showerhead to distribute the precursor vapor uniformly over a flat surface. The delivery system can be a ring to distribute the precursor vapor in a ring surrounding the workpiece. The delivery system can comprise a vaporizer to vaporize a liquid precursor or a solid precursor. The delivery system can comprise a liquid flow controller to control the amount of liquid precursor entering the process chamber. The delivery system can comprise a number of valves to control the timing of the precursor delivery.
The apparatus can further comprises a plurality of plasma sources coupled to the processing chamber. There can be only one plasma source in only one compartment, or there can be two plasma sources, one for each compartment. The plasma sources are capable of delivering a plasma onto the workpiece. The plasma sources are a part of the process requirements. The plasma can be used to excite the precursors, generating radical species, and increase the reaction rate. The plasma can be used for deposition processes, reaction processes, etching processes, or chamber clean processes. The plasma source can be an inductive coupled plasma source using radio frequency (RF). The plasma source can be a parallel plate plasma source using radio frequency (RF). The plasma source can be a remote plasma source. The plasma source can be a microwave plasma source using microwave frequency (MW).
The apparatus can further comprises a plurality of vacuum pumps coupled to the processing chamber. There can be only one vacuum pumps in only one compartment, or there can be two vacuum pumps, one for each compartment. The vacuum pumps are capable of maintaining the processing chamber at a pressure lower than atmospheric pressure. The compartment can have an isolation valve to isolate the compartment from the vacuum pump. The compartment can have a throttle valve to regulate the pressure in the compartment.
The apparatus can further comprises a plurality of workpiece bias power sources coupled to the processing chamber. There can be only one workpiece bias power source in only one compartment, or there can be two workpiece bias power sources, one for each compartment. The workpiece bias power source can be a direct current (DC) bias source, or a RF bias source. The workpiece bias power source can provide a potential bias to the workpiece to modify the path of the charged precursors, to provide bombardment to the workpiece.
In a preferred embodiment, the present invention apparatus comprises a two-compartment process chamber for sequential processing of a workpiece. The processing chamber comprises 2 compartments with each compartment having the processing equipment to process the workpiece. The processing equipment comprises a heater for heating the workpiece to an elevated temperature since many process recipes require that the workpiece is at a high temperature. The processing equipment comprises vacuum pumps to keep the process chamber at a reduced pressure. Typical process pressures are in the milliTorr range for etching conditions, and in the Torr range for deposition conditions, with 760 Torr being the atmospheric pressure. There can be one vacuum pump connected to one of the compartment, or there can be one vacuum pump connected to both compartments, or there can be two vacuum pumps connected to two compartments of the process chamber. There can be isolation valves between the compartments and the vacuum pumps to isolate the compartments from the vacuum pumps. There can be throttle valves between the compartments and the vacuum pumps to regulate the pressure in the compartments. The processing equipment comprises delivery systems to deliver precursors onto the workpiece. There can be one delivery system in one compartment, or there can be two delivery systems, one for each compartment. The apparatus is for sequential processing of a workpiece using two precursors for two compartments. Instead of a pump/purge step between the two precursors, the workpiece is moved between the two compartments. This arrangement has significant better advantages with liquid or solid precursors since the pump/purge step for vapors is much longer than gases in the prior art apparatus.
The apparatus can further comprise a plasma source, such as a microwave plasma source, to clean the compartment.
In another preferred embodiment, the present invention apparatus comprises a two-compartment process chamber for sequential processing of a workpiece with a plasma source. The processing chamber comprises 2 compartments with each compartment having the processing equipment to process the workpiece and one of the compartments having a plasma source for plasma processing. The processing equipment comprises a heater for heating the workpiece to an elevated temperature since many process recipes require that the workpiece is at a high temperature. The processing equipment comprises vacuum pumps to keep the process chamber at a reduced pressure. The processing equipment comprises delivery systems to deliver precursors onto the workpiece. The processing equipment comprises a plasma source for plasma processing of the workpiece.
The apparatus is for sequential processing of a workpiece using two precursors for two compartments with one compartment having a plasma source. The workpiece is exposed to the first precursor in the first compartment, then moves to the second compartment, and is exposed to a plasma environment with the second precursor in the second compartment. To strike a plasma, the amount of vapor needs to be minimized, therefore this arrangement has significant advantages over the pump/purge step of prior art. This arrangement is also well suited for metal deposition process with ICP plasma, since the first precursor, which is a metal precursor, will be confined in the first compartment, therefore the second compartment with the plasma is free of the metal precursor. For ICP plasma, the non-conductance window, such as a ceramic plate, needs to be free of metal for the transmission of the magnetic field for generating the plasma inside the compartment. The prior art one-compartment apparatus will require cleaning of the non-conductance window from the metal deposition for the reliable operation of the ICP plasma.
The apparatus can further comprise a plasma source, such as a microwave plasma source, to clean the first compartment.
A method of sequential process of a workpiece is disclosed. The method comprises the steps of:
The sequence can be repeated with the steps of transferring the workpiece back to the first compartment and processing the workpiece there. This sequential process method is different from the prior art sequential or ALD processing method in which the pump/purge step between the processing steps is replaced by a workpiece movement.
The workpiece processing step in step a) in the first compartment can comprise the deposition of a thin film. The characteristic of a deposition process is that the deposited film thickness increases noticeably as a function of processing time. The thin film deposition can occur by the introduction of appropriate precursors through a delivery system in the first compartment. By exposing the workpiece to appropriate precursors under appropriate conditions, a thin film can be deposited on the workpiece. The thickness of the deposited film can be from a monolayer to hundred of nanometers, controllable by various process conditions, such as the process time. A workpiece heater in the first compartment can supply the energy needed for the deposition reaction to take place. The workpiece heater can be a radiative heater or a resistive heater. A plasma or a bias source can also be added to supply the energy needed, or to modify the process characteristics. The process pressure can be sub-atmospheric, controlled by a throttle valve connected to a vacuum pump. The process pressure can be atmospheric, depended on the processes.
The workpiece processing step in step a) in the first compartment can comprise the adsorption of a thin film. The characteristic of an adsorption process is that the adsorbed film thickness does not increases noticeably as a function of processing time. The adsorbed film saturated at a certain thickness, typical less than a monolayer, after a period of processing time. This adsorption characteristics is the characteristics of the ALD process, to ensure a very good conformality of the coated film and to ensure a consistent thickness with a wide process margin. The thickness of the adsorbed film is typical less a monolayer, and is much more difficult to control than the deposited film.
The workpiece processing step in step c) in the second compartment can comprise the reaction of a precursor on the existing film. The workpiece processing step in step c) in the second compartment can comprise the plasma reaction of a precursor on the existing film. The existing film can be from a deposition step or from an adsorption process. The presence of the plasma can fasten the reaction process to improve the throughput. The deposited or adsorbed thin film is treated to form the same materials or a different material.
Implementations of the above aspect may include one or more of the following. The workpiece can be a wafer. The plasma enhances or maintains the thin film conformality. The plasma can be a high density plasma with higher than 5×109 ion/cm3. The reactant can be a metal organic, organic, to form a thin film of metal, metal nitride, or metal oxide. The second reactant can be exposed under high pressure above 100 mT. The first and second reactants react and the reaction creates a new compound. The thin film thickness is less than one atomic layer thickness. The thin film thickness is more than one atomic layer thickness. The thin film thickness can be between a fraction of a nanometer and tens of nanometers. The plasma can be sequentially pulsed for each layer to be deposited. The plasma can be excited with a solid state RF plasma source such as a helical ribbon electrode. The process includes pre-cleaning a surface of a workpiece; stabilizing precursor flow and pressure; exposing the workpiece to a first reactant in the first compartment, wherein the first reactant deposits or adsorbed on the workpiece to form a thin film; transferring the workpiece to the second compartment; striking the plasma; performing a plasma treatment on the deposited or adsorbed film; exposing the workpiece, coated with the first reactant, to a gaseous second reactant under the plasma treatment, wherein the thin film deposited by the first reactant is treated to form the same materials or a different material. Repeating of the steps deposits a thick film with thickness controlled by the number of repeats.
In another aspect, an apparatus to perform semiconductor processing includes a high density inductive coupled plasma generator to generate plasma; and a process compartment housing the plasma generator. The method can provide deposition of copper metal from Cu hfacI and plasma (gas), Cu hfacII and plasma (gas), CuI4 and plasma (gas), CuCl4 and plasma (gas), and organo metallic copper and plasma (gas); of titanium nitride from TDMAT and plasma (gas), TDEAT and plasma (gas), TMEAT and plasma (gas), TiCl4 and plasma (gas), TiI4 and plasma (gas), and organo metallic titanium and plasma (gas); of tantalum nitride from PDMAT and plasma (gas), PDEAT and plasma (gas), and organo metallic tantalum and plasma (gas); of aluminum oxide from trimethyl aluminum (TMA) and ozone, TMA and water vapor, TMA and oxygen, organo metallic aluminum and plasma (gas); and other oxides such as hafnium oxide, tantalum oxide, zirconium oxide; wherein gas is one of N2, H2, Ar, He, NH3, and combination thereof.
Implementations of the apparatus can include gas distribution, chuck, vaporizer, pumping port to pump, and port for gas purge.
Advantages of the system may include one or more of the followings. The pump/purge step is minimize, especially with liquid precursors or reactants. There is no extensive pump/purge step to remove all first precursors or reactants before introducing second precursors or reactants because the first and second precursors or reactants are confined in different compartment. There can be a small amount of pump/purge to minimize the amount of cross contamination, occurring during the workpiece transfer, but this pump/purge step is significantly small. Another advantage is that the chamber cleaning step can be minimize. With the first and second precursors separated, the deposition occurring in the chamber wall is much reduced, leading to less chamber wall cleaning. This is especially useful with metal deposition using ICP plasma, since the non-conducting window of the ICP plasma has to be cleaned of metal deposit. Another advantage is the improvement of uniformity, because a showerhead can be used in the first compartment and an ICP plasma in the second compartment.
Other advantages of the system may include one or more of the followings. The ICP plasma can use a helical ribbon instead of a coil. The helical ribbon provides a highly uniform plasma and also results in a chamber with a small volume. The system enables high precision etching, deposition or sputtering performance. This is achieved using the pulse modulation of a radio frequency powered plasma source, which enables a tight control the radical production ratio in plasmas, the ion temperature and the charge accumulation. Also, since the time for accumulation of charges in a wafer is on the order of milli-seconds, the accumulation of charges to the wafer is suppressed by the pulse-modulated plasma on the order of micro-seconds, and this enables the suppression of damage to workpieces on the wafer caused by the charge accumulation and of notches caused during the electrode etching process. The system requires that the substrate be heated to a relatively low temperature such as 400 degrees Celsius.
The compartment can be used for deposition step, such as CVD deposition, ALD deposition, plasma enhanced CVD deposition, metal organic CVD (MOCVD) deposition, sputtering deposition; or for treatment step such as rapid thermal annealing, laser annealing, plasma annealing, desorption; or for etching step such as metal etch, oxide etch, atomic layer etch.
The chamber 602 receives precursor gases through one or more gas inlets 604. A liquid precursor system 606 introduces liquid precursor through a vaporizer 609 into the chamber 602 using a precursor distribution ring 630.
A chuck 608 movably supports a workpiece or a substrate 610. In
The sequential process can be accomplished with a pump/purge step. A first precursor is introduced and the substrate is exposed to the first precursor to form a thin film. A pump/purge step is followed to remove the first precursor. Then a second precursor is introduced and the substrate is exposed to the second precursor to react with the existing thin film. In the plasma sequential chamber, a plasma is generated during the introduction of the second precursor to accelerate the reaction. Another pump/purge step is then followed to remove the second precursor. Then the sequence is repeated until the process is completed. To generate a plasma, the chamber needs to be free of precursor vapor, therefore a long pump/purge cycle is often needed. Also, to achieve a high density plasma in a large uniform area, such as for a 8″ diameter semiconductor wafer, ICP plasma is the obvious choice. But to generate the plasma, the window needs to be free of metal deposit. Therefore for a metal deposition sequence, a window clean step will need to be included. The throughput of the process is significantly reduced with these pump/purge and cleaning actions.
To improve the throughput, workpieces can be processed simultaneously in both compartments.
In the new position, pathway door 1131 will close the other side of internal pathway 1142, and pathway door 1130 will also close the other side of internal pathway 1141. Thus the two compartments will be isolated again with the workpieces are now in different compartments. Thus by swinging back and forther, the workpiece mover 1125 allows the sequential processing of two workpieces simultaneously in 2 different process compartment.
The pathway doors 1131 and 1132 and the two sides of both internal pathways 1141 and 1142 are designed so that the doors can close the pathways in either direction. The amount of rotation is shown in
The chamber 1107 has an external pathway 1140 to move a workpiece in and out of the chamber. A workpiece 1123 is first moved into the compartment 1121, then the workpiece mover 1125 rotates clockwise, moving the workpiece 1123 into the compartment 1122. A workpiece 1124 is then can be moved into compartment 1121, and the chambers are then ready for processing both workpieces. Alternatively, after the workpiece 1123 moved into the comaprtment 1121, and before the workpiece mover 1125 rotation, workpiece 1123 can be first processed in compartment 1121. After finished processing, workpiece mover 1125 then rotates clockwise, and the cycle continues. After process finishing, the workpieces can be removed one at a time with the workpiece mover rotating to exposed the workpieces to the external pathway.
The loading of the workpieces can be accomplished as followed. The workpiece mover can rotate to the first compartment to load the workpieces onto the first positions on the workpiece mover, then the workpiece mover is rotated to the second compartment, bringing the loaded workpieces to the second compartment. The workpiece mover is then ready to load workpieces onto the second position on the workpiece mover. The processing of the workpieces can wait until all workpieces are loaded before starting processes on both compartments. Or the first workpieces can be loaded into first compartment with first process, then rotated to second compartment with second process while the first compartment is loading the second workpieces and first process. The workpiece mover then rotates back and forth to process workpieces in both compartments simultaneously.
To enable the workpiece mover 1125 to rotate properly, the chamber 1107 would need to be a full circle. Thus to further improve the throughput, a multiple of two workpieces (for example, 4, 6, or 8 workpieces) can also be arranged.
In another embodiment, the pathway doors fit in the pathway. In this embodiment, the sealing of the pathway is different than previous embodiments using face sealing. In previous embodiments, the pathway doors are larger than the pathway opening, thus the sealing can be accomplished by face sealing, meaning the sealing surface is the face of the pathway doors. In this embodiment, since the pathway doors fit in the pathway, the pathway doors are smaller than the pathway opening, and thus there is no face sealing. The sealing surface is then the circumference of the pathway opening. The sealing surface could be considered as a moving seal since the pathway doors would slide against the sealing surface. There are various variations of this embodiment. One provides an o-ring seal around the circumference of the pathway opening, and when the pathway doors entering the pathway opening, slide against the o-ring to seal the opening. Other provides a small gap between the pathway doors and the pathway opening. The size of the gap would be chosen to optimize the cross contamination between the two compartments. Furthermore, there might be some purging or pumping in the vicinity of the sealing area to prevent cross contamination.
One advantage of this embodiment where the pathway doors fit in the pathway is that the workpiece mover can keep rotating in the same direction instead of rotating back and forth. And with the workpiece mover fully rotatable, the loading of the workpieces to the workpiece mover can be accomplished with the workpiece mover rotates to the proper location. With the pathway doors fitting into the pathway, even if the workpiece mover rotates back and forth, the rotation angle of the workpiece mover can be close to full circle, thus the loading of workpieces would be simplified since all locations on the workpiece mover can be exposed to a loading station.
It should be realized that the above examples represent a few of a virtually unlimited number of applications of the plasma processing techniques embodied within the scope of the present invention. Furthermore, although the invention has been described with reference to the above specific embodiments, this description is not to be construed in a limiting sense. For example, the duty ratios, cycle times and other parameters/conditions may be changed in order to obtain a desired characteristic for the process on the wafer.
Various modifications of the disclosed embodiment, as well as alternative embodiments of the invention will become apparent to persons skilled in the art upon reference to the above description. The invention, however, is not limited to the embodiment depicted and described. For instance, the radiation source can be a radio frequency heater rather than a lamp. Hence, the scope of the invention is defined by the appended claims. It is further contemplated that the appended claims will cover such modifications that fall within the true scope of the invention.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/212,547, filed Aug. 6, 2002, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10212547 | Aug 2002 | US |
| Child | 11138043 | May 2005 | US |
