Patent Publication Number: US-8119540-B2

Title: Method of forming a stressed passivation film using a microwave-assisted oxidation process

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
     This application is related to co-pending U.S. patent application Ser. No. 12/058,570, entitled “METHOD OF FORMING A STRESSED PASSIVATION FILM USING AN NON-IONIZING ELECTROMAGNETIC RADIATION-ASSISTED OXIDATION PROCESS,” filed on the same date as the present application, the entire content of which is hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to forming a stressed passivation film in semiconductor processing, and more particularly to a method of forming a stressed silicon oxynitride film. 
     BACKGROUND OF THE INVENTION 
     In the construction of integrated circuit devices, a topside or passivation film of a dielectric material is conventionally provided over the underlying layers containing the integrated circuit structure. This film, in addition to functioning as an insulation film, acts to protect the underlying structure from moisture and ion contamination that can damage or destroy the structure by causing corrosion and electrical shorts. 
     Silicon nitride is known as a satisfactory insulation layer for forming such a passivation film, due at least in part to its high resistance to moisture and hydrogen penetration. Moreover, the diffusivity of various impurities, such as sodium, is much lower in silicon nitride than in other insulators, such as silicon dioxide. Thus, integrated circuits made with a silicon nitride passivation layer are less susceptible to ionic contamination problems. 
     Recent innovations to improve complementary metal oxide semiconductor (CMOS) transistor performance have created an industry need for stressed ceramic layers compatible with current ultra-large scale integration (ULSI) techniques. In particular, channel carrier mobility for a negative metal oxide semiconductor (NMOS) transistors can be increased through introduction of tensile uniaxial or biaxial strain on a channel region of a MOS transistor. Typically, this has been accomplished by deposition of highly tensile stressed silicon nitride as a cap layer over the source/drain regions. While other novel materials may be explored for this application, silicon nitride and silicon nitride based materials are preferable due to their compatibility with existing fabrication processes. 
     SUMMARY OF THE INVENTION 
     In one embodiment of the present invention, a method is described for forming a stressed passivation film over an integrated circuit structure. The stressed passivation film is formed by depositing a silicon nitride film over the integrated circuit structure and subsequently oxidizing at least a top portion of the silicon nitride film to create or increase stress in the film and improve the performance of the device containing the integrated circuit structure. According to embodiments of the invention, the oxidation process is performed using low-energy excited oxygen species that eliminate or at least significantly reduce oxidation and/or damage to underlying materials and devices. 
     In one embodiment, the method includes depositing a silicon nitride film over an integrated circuit structure on a substrate and embedding oxygen into a surface of the silicon nitride film by exposing the silicon nitride film to a process gas containing an oxygen-containing gas or an oxygen- and nitrogen-containing gas excited by plasma induced dissociation using plasma based on microwave irradiation via a plane antenna member having a plurality of slots, where the plane antenna member faces the substrate containing the silicon nitride film. The method further includes heat-treating the oxygen-embedded silicon nitride film to form a stressed silicon oxynitride film. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the present invention and many attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a schematic showing a cross-sectional view of a MOS device including a stressed silicon oxynitride film according to an embodiment of the invention; 
         FIG. 2  is a schematic diagram of a vacuum processing tool for forming a stressed silicon oxynitride film according to an embodiment of the invention; 
         FIG. 3  is a process flow diagram for forming a stressed silicon oxynitride film on a substrate according to an embodiment of the invention; 
         FIG. 4  is a process flow diagram for forming a stressed silicon oxynitride film on a substrate according to another embodiment of the invention; 
         FIG. 5  is a schematic diagram of a film deposition system for depositing a silicon nitride film on a substrate according to one embodiment of the invention; 
         FIG. 6  is a schematic diagram of a processing system containing a non-ionizing electromagnetic radiation source for performing an oxidation process according to one embodiment of the invention; 
         FIG. 7  is a schematic diagram of another processing system containing a non-ionizing electromagnetic radiation source for performing an oxidation process according to one embodiment of the invention; and 
         FIG. 8  is a schematic diagram of a plasma processing system containing a slot plane antenna (SPA) plasma source for performing an oxidation process according to one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS 
     Methods for forming a stressed passivation film in semiconductor processing are described in various embodiments. One skilled in the relevant art will recognize that the various embodiments may be practiced without one or more of the specific details, or with other replacement and/or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of various embodiments of the invention. Similarly, for purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the invention. Furthermore, it is understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, but do not denote that they are present in every embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention. 
     There is a general need for new methods for forming stressed passivation films under well-controlled process conditions that provide great flexibility for tailoring the material properties and the stress induced in the films that improve device performance. The new methods are needed for replacing ion implantation methods that utilize high kinetic energy ion beams and methods that utilize direct exposure of the films to high kinetic energy oxygen (O) species such as O ions excited by conventional plasma processing systems and plasma processing conditions. These methods to be replaced have several drawbacks, including charging damage of the exposed films and poor control over the depth profiles of elements embedded in the films. These drawbacks become increasingly more important as films in semiconductor devices become increasingly thinner. 
     In particular, new methods are needed that integrate deposition of silicon nitride or silicon nitride based films and in-situ (without air exposure) oxidation of the silicon nitride or silicon nitride based film by low-energy excited oxygen (O) species in a process gas containing an oxygen-containing gas (e.g., O 2 , H 2 O, or H 2 O 2 ) or an oxygen- and nitrogen-containing gas (e.g., NO, N 2 O, or NO 2 ). Embodiments of the invention use low-energy excited oxygen species in an oxidation process where the oxidation of the films does not exceed the thickness of the films, thereby eliminating or at least significantly reducing oxidation and/or damage to underlying materials and devices. The in-situ processing provides excellent control over the extent of film oxidation and oxidation depth profile, and reduces contamination due to the absence of atmospheric exposure during processing. 
     The silicon nitride films contain silicon (Si) and nitrogen (N), for example as SiN x , and the silicon oxynitride films contain Si, N, and O, for example as SiN x O y . The silicon nitride based films can, in addition to Si and N, further contain carbon (C), hydrogen (H), or both C and H. Furthermore, the silicon oxynitride films can, in addition to Si, N, and O, further contain C, H, or both C and H. In the following description, silicon nitride films and silicon nitride based films are referred to simply as silicon nitride films. Composition of a silicon oxynitride film can vary from an external surface of the silicon oxynitride film exposed to the low-energy oxygen species to an interface between the silicon oxynitride film and a non-oxidized portion of the silicon nitride film. However, the interface may not be abrupt, but may be described by a smooth, continuous reduction in oxygen concentration from the oxygen content of the external surface of the silicon oxynitride film to the oxygen content of the silicon nitride film. According to an embodiment of the invention, a thickness of the silicon nitride film can be between about 5 nanometers (nm) and about 50 nm and a thickness of a surface layer of the silicon nitride film containing embedded oxygen can be between about 3 nm and about 10 nm. 
       FIG. 1  is a schematic showing a cross-sectional view of a MOS device including a stressed silicon oxynitride film according to an embodiment of the invention. The device  180  includes a substrate  182  having doped regions  183  and  184  (e.g., source and drain), a gate stack  190 , and a stressed silicon oxynitride film  192 . The substrate  182  can, for example, be a semiconductor substrate, such as a silicon substrate, a silicon germanium substrate, a germanium substrate, a glass substrate, a LCD substrate, or a compound semiconductor substrate such as for example GaAs. The substrate  182  can be of any size, for example, a 200 mm substrate, a 300 mm substrate, or an even larger substrate. 
     The gate stack  190  includes a dielectric layer  186  on the channel region  185 . The dielectric layer  186  can for example include a silicon dioxide layer, a silicon nitride layer, a silicon oxynitride layer, or a combination thereof, or any other appropriate material. The dielectric layer  186  can further include a high-dielectric constant (high-k) material. The high-k material can for example include a metal oxide, a metal oxynitride, a metal silicate, or a metal silicon oxynitride. Examples of the high-k materials include Ta 2 O 5 , TiO 2 , Al 2 O 3 , Y 2 O 3 , BaO, ZrO 2 , HfO 2 , SrO x , LaO x , YO x , ZrNO x , HfNO x , ZrSiO x , HfSiO x , TaSiO x , SrSiO x , LaSiO x , YSiO x , ZrSiNO x , or HfSiNO x , or a combination of two or more thereof. The high-k material is not limited to the above-mentioned materials and may contain other simple or complex oxides, silicates, and oxynitrides suitable for fabrication of advanced semiconductor devices. In one example, a thickness of the high-k material can between about 1 nm and about 5 nm, or between about 1.2 nm and about 3 nm. 
     In one embodiment, a conductive layer  187  (e.g., a gate electrode layer) is formed on the dielectric layer  186 , and a silicide layer  188  is formed on the conductive layer  187  to reduce the electrical resistance of the conductive layer  187 . A cap layer  189  can be positioned at the top of the gate stack  190  to protect the gate stack  190 . The cap layer  189  can, for example, be a silicon nitride or silicon oxynitride layer. In one example, the conductive layer  187  can be doped polycrystalline silicon (poly-Si), and the silicide layer  188  can be tungsten silicide. Furthermore, the device  180  and the gate stack  190  may include different and fewer or more layers than shown in  FIG. 1 . In one example, conductive layer  187  and/or silicide layer  188  may be replaced by a metal gate layer.  FIG. 1  further shows a spacer  181  formed on either side of the gate stack  190  in order to protect the gate stack  190  from damage and ensure electrical performance of the gate stack  190 . In addition, the spacer  181  can be used as a hard mask for the formation of the source  183  and drain  184  of the MOS device  180 . Alternatively, in one embodiment of the present invention, more than one spacer  181  may be used. The MOS device depicted in  FIG. 1  may be further processed to complete a semiconductor device. 
     In one embodiment of the present invention, the device  180  can be a NMOS device where stressed silicon oxynitride film  192  increases channel carrier mobility through introduction of a tensile stress on the channel region  185 . The stressed silicon oxynitride film  192  can also serve as a passivation film for protecting the device  180 . According to one embodiment of the present invention, the stressed silicon oxynitride film  192  may have a tensile stress equal to or greater than about 1.5 GPa (1.5×10 9  Pascal). 
       FIG. 2  is a schematic diagram of a vacuum processing tool for forming a stressed silicon oxynitride film according to an embodiment of the invention. The vacuum processing tool  500  contains a first substrate (wafer) transfer system  501  that includes cassette modules  501 A and  501 B, and a substrate alignment module  501 C. Load-lock chambers  502 A and  502 B are coupled to the substrate transfer system  501  using gate valves G 1  and G 2 , respectively. The first substrate transfer system  501  is maintained at atmospheric pressure but a clean environment is provided by purging with an inert gas. The load lock chambers  502 A and  502 B are coupled to a second substrate transfer system  503  using gate valves G 3  and G 4 . The second substrate transfer system  503  may be maintained at a base pressure of about 100 mTorr, or lower, using a turbomolecular pump (not shown). The second substrate transfer system  503  includes a substrate transfer robot and is coupled to degassing system  504 A, precleaning system  504 B for precleaning a substrate or an integrated circuit structure on a substrate prior to further processing, and auxiliary processing system  504 C. The processing systems  504 A,  504 B, and  504 C are coupled to the second substrate transfer system  503  using gate valves G 5 , G 6 , and G 7 , respectively. 
     Furthermore, the second substrate transfer system  503  is coupled to a third substrate transfer system  505  through substrate handling chamber  504 D and gate valve G 8 . As in the second substrate transfer system  503 , the third substrate transfer system  505  may be maintained at a base pressure of about 100 mTorr, or lower, using a turbomolecular pump (not shown). The third substrate transfer system  505  includes a substrate transfer robot. Coupled to the third substrate transfer system  505  are first processing system  506 A configured for depositing a silicon nitride film on a substrate, and second processing system  506 D configured for embedding oxygen into a surface of a silicon nitride film by exposing the silicon nitride film to a process gas containing an oxygen-containing gas (e.g., O 2 , H 2 O, or H 2 O 2 ) or an oxygen- and nitrogen-containing gas (e.g., NO, N 2 O, or NO 2 ) exited by plasma induced dissociation using plasma formed by microwave irradiation via a plane antenna member having a plurality of slots. Furthermore, coupled to the third substrate transfer system  505  are third processing system  506 B configured for embedding oxygen into a surface of a silicon nitride film by exposing the silicon nitride film to a process gas containing oxygen radicals formed by non-ionizing electromagnetic (e.g., ultraviolet (UV)) radiation induced dissociation of the oxygen-containing gas or the oxygen- and nitrogen-containing gas, and fourth processing system  506 C configured for low-pressure heat-treating of silicon oxynitride films following processing of the silicon nitride films in processing systems  506 B or  506 D. The processing systems  506 A,  506 B,  506 C, and  506 D are coupled to the substrate transfer system  505  using gate valves G 9 , G 10 , G 11 , and G 12 , respectively. 
     According to one embodiment of the invention, the first processing system  506 A can include a film deposition system  1  schematically shown in  FIG. 5 . According to an embodiment of the invention, the second processing system  506 D can be a plasma processing system containing a slot plane antenna (SPA) plasma source; one example of such a plasma processing system is shown in  FIG. 8 . According to an embodiment of the invention, the third processing system  506 B can be a processing system containing a non-ionizing electromagnetic ultraviolet (UV) excitation source; examples of such a processing system are shown in  FIGS. 6 and 7 . The third substrate transfer system  505  and processing systems  506 A- 506 D are capable of maintaining a base pressure of background gases at about 100 mTorr, or lower, during the integrated processing, thereby enabling formation of stressed silicon oxynitride films under well-controlled process conditions that provide great flexibility for tailoring the material properties and stress induced in the films. 
     The vacuum processing tool  500  includes a controller  510  that can be coupled to and control any or all of the processing systems and processing elements depicted in  FIG. 2  during the integrated substrate processing. Alternatively, or in addition, controller  510  can be coupled to one or more additional controllers/computers (not shown), and controller  510  can obtain setup and/or configuration information from an additional controller/computer. The controller  510  can be used to configure any or all of the processing systems and processing elements, and the controller  510  can collect, provide, process, store, and display data from any or all of the processing systems and processing elements. The controller  510  can include a number of applications for controlling any or all of the processing systems and processing elements. For example, controller  510  can include a graphic user interface (GUI) component (not shown) that can provide easy to use interfaces that enable a user to monitor and/or control one or more processing systems processing elements. 
     The controller  510  can include a microprocessor, memory, and a digital I/O port capable of generating control voltages sufficient to communicate, activate inputs, and exchange information with the vacuum processing tool  500  as well as monitor outputs from the vacuum processing tool  500 . For example, a program stored in the memory may be utilized to activate the inputs of the vacuum processing tool  500  according to a process recipe in order to perform integrated substrate processing. 
     However, the controller  510  may be implemented as a general purpose computer system that performs a portion or all of the microprocessor based processing steps of the invention in response to a processor executing one or more sequences of one or more instructions contained in a memory. Such instructions may be read into the controller memory from another computer readable medium, such as a hard disk or a removable media drive. One or more processors in a multi-processing arrangement may also be employed as the controller microprocessor to execute the sequences of instructions contained in main memory. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions. Thus, embodiments are not limited to any specific combination of hardware circuitry and software. 
     The controller  510  includes at least one computer readable medium or memory, such as the controller memory, for holding instructions programmed according to the teachings of the invention and for containing data structures, tables, records, or other data that may be necessary to implement the present invention. Examples of computer readable media are compact discs, hard disks, floppy disks, tape, magneto-optical disks, PROMs (EPROM, EEPROM, flash EPROM), DRAM, SRAM, SDRAM, or any other magnetic medium, compact discs (e.g., CD-ROM), or any other optical medium, punch cards, paper tape, or other physical medium with patterns of holes, a carrier wave (described below), or any other medium from which a computer can read. 
     Stored on any one or on a combination of computer readable media is software for controlling the controller  510 , for driving a device or devices for implementing the invention, and/or for enabling the controller  510  to interact with a human user. Such software may include, but is not limited to, device drivers, operating systems, development tools, and applications software. Such computer readable media further includes the computer program product of the present invention for performing all or a portion (if processing is distributed) of the processing performed in implementing embodiments of the invention. 
     The computer code devices of the present invention may be any interpretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynamic link libraries (DLLs), Java classes, and complete executable programs. Moreover, parts of the processing of the present invention may be distributed for better performance, reliability, and/or cost. 
     The controller  510  may be locally located relative to the vacuum processing tool  500 , or it may be remotely located relative to the vacuum processing tool  500 . For example, the controller  510  may exchange data with the vacuum processing tool  500  using at least one of a direct connection, an intranet, the Internet and a wireless connection. The controller  510  may be coupled to an intranet at, for example, a customer site (i.e., a device maker, etc.), or it may be coupled to an intranet at, for example, a vendor site (i.e., an equipment manufacturer). Additionally, for example, the controller  510  may be coupled to the Internet. Furthermore, another computer (i.e., controller, server, etc.) may access, for example, the controller  510  to exchange data via at least one of a direct connection, an intranet, and the Internet. As also would be appreciated by those skilled in the art, the controller  510  may exchange data with the vacuum processing tool  500  via a wireless connection. 
     As those skilled in the art will readily recognize, embodiments of the invention may not require the use of all the processing systems of the vacuum processing tool  500  depicted in  FIG. 2 . For example, according to one embodiment, either the second processing system  506 D or the third processing system  506 B are used for embedding oxygen into a silicon nitride film. Thus, some embodiments of the invention may include the use of less than all the processing systems depicted in  FIG. 2 . 
       FIG. 3  is a process flow diagram for forming a stressed silicon oxynitride film on a substrate according to an embodiment of the invention. In block  302  of process flow  300 , a substrate is provided in vacuum processing tool, for example vacuum processing tool  500  depicted in  FIG. 2 . The substrate can, for example, be a Si substrate. A Si substrate can be of n- or p-type, depending on the type of device being formed. The substrate can contain an integrated structure thereon, for example the gate stack  190  depicted in  FIG. 1 . 
     According to one embodiment of the invention, the substrate is provided in the cassette modules  501 A or  501 B for processing in the vacuum processing tool  500 . The substrate is introduced into the substrate transfer system  503  from the substrate transfer system  501  through the gate valve G 1  and the load lock chamber  502 A or through the gate valve G 2  and the load lock chamber  502 B, after a substrate aligning step in the substrate alignment module  501 C. The substrate is then transferred from the substrate transfer system  503  to the processing system  504 A through the gate valve G 5 . In the processing system  504 A, the substrate may be degassed by heating and/or exposed to ultraviolet radiation in an inert gas environment to remove water and any residual gas from the substrate. 
     After degassing in the processing system  504 A, the substrate is returned to the substrate transfer system  503  through the gate valve G 5 , and next the substrate is optionally transported to the (precleaning) processing system  504 B through the gate valve G 6 . Following the optional precleaning, the substrate is returned to the substrate transfer system  503  through the gate valve G 6 , and then transferred to the substrate transfer system  505  from the substrate handling chamber  504 D through the gate valve G 8 . Once in the substrate transfer system  505 , the substrate is introduced into the first processing system  506 A through the gate valve G 9  for depositing a silicon nitride film on the substrate in block  304 . 
     After deposition of the silicon nitride film in the first processing system  506 A, the substrate is returned to the third substrate transfer system  505  through the gate valve G 9 . Next, the substrate is introduced into the third processing system  506 B through the gate valve G 10  for embedding oxygen into a surface of the silicon nitride film in block  306 . The oxidizing in block  306  includes exposing the silicon nitride film to a process gas containing oxygen radicals formed by non-ionizing electromagnetic radiation induced dissociation of an oxygen-containing gas or an oxygen- and nitrogen-containing gas. In one example, the third processing system  506 B can include a processing system  101  schematically shown in  FIG. 6 . In another example, the third processing system  506 B can include a processing system  550  schematically shown in  FIG. 7 . 
     Oxidation of a silicon nitride film in the processing system  101  can include a substrate temperature between about 25° C. and about 800° C., for example about 400° C. Alternatively, the substrate temperature can be between about 400° C. and about 700° C. The pressure in the process chamber  450  can, for example, be maintained between about 100 mTorr and about 10 Torr, for example about 50 mTorr. Alternatively, the pressure can be maintained between about 20 mTorr and about 1 Torr. 
     Following the oxidation process in block  306 , the substrate is returned to the substrate transfer system  505  through the gate valve G 12  and introduced into the fourth processing system  506 C through the gate valve G 11  for heat-treating the oxygen-embedded silicon nitride film in block  308  to form a silicon oxynitride film with a desired oxygen depth profile (oxygen concentration as a function of depth in the silicon oxynitride film) and to improve the electrical and material properties of the silicon oxynitride film. 
     According to embodiments of the invention, the heat-treating can be performed in the fourth processing system  506 C as described above, but alternatively or in addition, the heat-treating may be performed in processing systems  506 A,  506 B, or  506 D. According to one embodiment, the step of embedding oxygen into a surface of the silicon nitride film in block  306  can at least partially overlap with the heat-treating step in block  308 . According to another embodiment, the steps in blocks  306  and  308  may have no temporal overlap. The heat-treating conditions can include a pressure of about 50 mTorr to about 760 Torr, or a pressure of about 1 Torr to about 10 Torr, using a gas containing O 2 , N 2 , H 2 , Ar, He, Ne, Xe, or Kr, or any combination thereof at a flow rate of 0 to 20 standard liters per minute (slm), or at a flow rate of 0.1 slm to 5 slm. The heat-treating may be carried out for a time period between about 5 seconds and about 5 minutes, or between about 30 seconds and about 2 minutes. 
     After the heat-treating in block  308 , the heat-treated substrate is returned to the substrate transfer system  505  and to the substrate transfer system  503  through the gate valve G 11  and the substrate handling chamber  504 D. Thereafter, the substrate is returned to the substrate transfer system  501  from the substrate transfer system  503  through the gate valve G 3 , load lock chamber  502 A and the gate valve G 1 , or through the gate valve G 4 , the load lock chamber  502 B and the gate valve G 2 . Next, the substrate is returned to the cassette module  501 A or  501 B and removed from the vacuum processing tool  500 . 
     According to one embodiment of the invention, the depositing and oxidizing steps in blocks  304  and  306  may be sequentially performed any number of times to form a plurality of oxygen-embedded silicon nitride films that may subsequently be heat-treated in block  308  to form a plurality of silicon oxynitride films. Alternatively, each of the oxygen-embedded silicon nitride films may be heat-treated before the next silicon nitride film is deposited thereon. According to one embodiment, the step of embedding oxygen into a surface of the silicon nitride film in block  306  can at least partially overlap with the heat-treating step in block  308 . 
       FIG. 4  is a process flow diagram for forming a stressed silicon oxynitride film on a substrate according to another embodiment of the invention. The process flow  400  in  FIG. 4  is similar to the process flow  300  in  FIG. 3 , and includes, in block  402 , providing a substrate in a vacuum processing tool, for example vacuum processing tool  500  depicted in  FIG. 2 . The substrate can, for example, be a Si substrate. A Si substrate can be of n- or p-type, depending on the type of device being formed. The substrate can contain an integrated structure thereon, for example the gate stack  190  depicted in  FIG. 1 . After degassing and optional precleaning, the substrate is introduced into the first processing system  506 A through the gate valve G 9  for depositing a silicon nitride film on the substrate in block  404 . After deposition of the silicon nitride film, the substrate is returned to the substrate transfer system  505  through the gate valve G 9 . 
     Next, the substrate is introduced into the second processing system  506 D through the gate valve G 12  for embedding oxygen into a surface of the silicon nitride film in block  406 . The oxidizing includes exposure to a process gas containing an oxygen-containing gas or an oxygen- and nitrogen-containing gas excited by plasma induced dissociation using plasma based on microwave irradiation via a plane antenna member having a plurality of slots, where the plane antenna member faces an upper surface of a substrate to be processed. In one example, the second processing system  506 D can include a plasma processing system  410  schematically shown in  FIG. 8 . 
     According to one embodiment of the invention, the oxidizing in block  406  can further include simultaneously exposing the silicon nitride film to oxygen radicals formed by remote plasma induced dissociation of a second process gas comprising an oxygen-containing gas or an oxygen- and nitrogen-containing gas. The remote plasma source is coupled to the process chamber containing the silicon nitride film. Thus, the silicon nitride film is not exposed directly to the remote plasma source but to oxygen radicals formed by the remote plasma induced dissociation of the second process gas. The remote plasma source can couple radio frequency (RF) power to the second process gas, and the oxygen radicals are subsequently flowed into the process chamber using the gas line and exposed to the silicon nitride film. In one example, the plasma processing system  410  schematically shown in  FIG. 8  is configured for exposing the silicon nitride film to oxygen radicals formed by remote plasma induced dissociation of a process gas comprising an oxygen-containing gas or an oxygen- and nitrogen-containing gas. According to one embodiment of the invention, exposure of the silicon nitride film to the oxygen radicals from the remote plasma source and to the oxygen gas excited by plasma induced dissociation based on microwave irradiation via a plane antenna member having plurality of slots can have at least partial temporal overlap. According to another embodiment, the exposures of the silicon nitride film to oxygen radicals formed by the remote plasma source can be performed before or after the embedding in block  406 . 
     Next, the substrate is returned to the substrate transfer system  505  through the gate valve G 12  and introduced into the fourth processing system  506 C through the gate valve G 11  for heat-treating the oxygen-embedded silicon nitride film in block  408 . Next, the heat-treated substrate is returned to the substrate transfer system  505  and removed from the vacuum processing tool  500  as described above. 
       FIG. 5  is a schematic diagram of a film deposition system for depositing a silicon nitride film on a substrate according to one embodiment of the invention. The film deposition system  1  is capable of depositing a silicon nitride film on substrate  25  by a thermal chemical vapor deposition (CVD) process, a plasma-enhanced CVD (PECVD) process, or an atomic layer deposition (ALD) process, for example. The film deposition system  1  contains a process chamber  10  having a substrate holder  20  configured to support the substrate  25  to be processed. The substrate holder  20  is mounted on a pedestal  5  on a lower surface  65  of the substrate holder  20 . 
     The substrate  25  is transferred into and out of the process chamber  10  through a gate valve G 9  via substrate transfer system  505 . When transferred into the process chamber  10 , the substrate  25  is received by a lift mechanism  48  containing substrate lift pins  22  housed in holes  24  within the substrate holder  20 . The film deposition system  1  contains three lift pins  22  (only two are shown in  FIG. 5 ). The lift pins  22  are made of quartz or a ceramic material such as Al 2 O 3 , SiO 2 , or AlN. Once the substrate  25  is received from the substrate transfer system  505 , it is lowered to an upper surface of the substrate holder  20 . The lower end portion of each lift pin  22  rests against a support plate  56  attached to an arm  54 . The arm  54  is connected to a rod  46  of an actuator  58  positioned below the process chamber  10 . The rod  46  extends through bellows  64  positioned at the bottom on the process chamber  10 . 
     The process chamber  10  contains an upper assembly  30  coupled to a first process material supply system  40 , a second process material supply system  42 , and a purge gas supply system  44 . The upper assembly  30  can contain a showerhead having a large number of gas delivery holes formed in a lower surface of the showerhead and facing the substrate  25  for delivering gases  15  into processing space  70  above the substrate  25 . The first process material supply system  40  and the second process material supply system  42  can be configured to simultaneously or alternately introduce first and second process materials to the process chamber  10 . The alternation of the introduction of the first and second process materials can be cyclical, or it may be acyclical with variable time periods between introduction of the first and second process materials. 
     The first process material can contain a deposition gas containing a silicon precursor which may be delivered to process chamber  10  in a gaseous phase with or without the use of a carrier gas. The second process material can contain a reducing agent, which may include a nitrogen precursor containing nitrogen to be incorporated in a silicon nitride film formed on the substrate  25 . For instance, the reducing agent may be delivered to process chamber  10  in a gaseous phase with or without the use of a carrier gas. Examples of silicon precursors include silane (SiH 4 ), disilane (Si 2 H 6 ), monochlorosilane (SiH 3 Cl), dichlorosilane (SiH 2 Cl 2 ), trichlorosilane (SiHCl 3 ), hexachlorodisilane (Si 2 Cl 6 ), tetrakis(dimethylamino)silane (TDMAS), tris(dimethylamino)silane (TrDMAS), diethylsilane (Et 2 SiH 2 ), tetrakis(ethylmethylamino)silane (TEMAS), bis(diethylamino)silane, bis(di-isopropylamino)silane (BIPAS), tris(isopropylamino)silane (TIPAS), (di-isopropylamino)silane (DIPAS), and bis(tertiarybutylamino)silane (BTBAS). Examples of nitrogen precursors include N 2 , NH 3 , N 2 H 4 , and C 1 -C 10  alkylhydrazine compounds. Common C 1  and C 2  alkylhydrazine compounds include monomethyl-hydrazine (MeNHNH 2 ), 1,1-dimethyl-hydrazine (Me 2 NNH 2 ), and 1,2-dimethyl-hydrazine (MeNHNHMe). 
     Exemplary processing conditions during deposition of a silicon nitride film include a substrate temperature between about 400° C. and about 800° C., for example about 700° C., and a process chamber pressure between about 50 mTorr and about 200 Torr, for example about 1 Torr. 
     The purge gas supply system  44  is configured to introduce a purge gas to process chamber  10 . For example, the introduction of purge gas may occur during and/or between introduction of the first and second process materials to the process chamber  10 , or following the introduction of the second process material to process chamber  10 . The purge gas can contain an inert gas, such as a noble gas (i.e., helium, neon, argon, xenon, krypton), or nitrogen (N 2 ), or hydrogen (H 2 ). 
     The film deposition system  1  contains a plasma generation system configured to optionally generate plasma in the processing space  70  during deposition of the silicon nitride film. The plasma generation system includes a first power source  50  coupled to the process chamber  10  and configured to couple power to the first process material, or the second process material, or both, in the processing space  70  by energizing the upper assembly  30 . The first power source  50  may be a variable power source and may include a radio frequency (RF) generator and an impedance match network, and may further include an electrode through which RF power is coupled to the plasma in process chamber  10 . The electrode can be formed in the upper assembly  30 , and it can be configured to oppose the substrate holder  20 . The impedance match network can be configured to optimize the transfer of RF power from the RF generator to the plasma by matching the output impedance of the match network with the input impedance of the process chamber, including the electrode, and plasma. For instance, the impedance match network serves to improve the transfer of RF power to plasma in process chamber  10  by reducing the reflected power. Match network topologies (e.g. L-type, T-type, T-type, etc.) and automatic control methods are well known to those skilled in the art. A typical frequency for the application of RF power to the electrode formed in the upper assembly  30  can, for example, range from 10 MHz to 200 MHz and can be 60 MHz, and the RF power applied can, for example, be between about 500 Watts (W) and about 2200 W. 
     Alternatively, the first power source  50  may include a radio frequency (RF) generator and an impedance match network, and may further include an antenna, such as an inductive coil, through which RF power is coupled to plasma in process chamber  10 . The antenna can, for example, include a helical or solenoidal coil, such as in an inductively coupled plasma source or helicon source, or it can, for example, include a flat coil as in a transformer coupled plasma source. 
     Alternatively, the first power source  50  may include a microwave frequency generator, and may further include a microwave antenna and microwave window through which microwave power is coupled to plasma in process chamber  10 . The coupling of microwave power can be accomplished using electron cyclotron resonance (ECR) technology, or it may be employed using surface wave plasma technology, such as a slotted plane antenna (SPA), as described in U.S. Pat. No. 5,024,716, entitled “Plasma processing apparatus for etching, ashing, and film-formation”; the contents of which are herein incorporated by reference in its entirety. 
     The film deposition system  1  contains a substrate bias system configured to optionally generate or assist in generating plasma during deposition of the silicon nitride film. The substrate bias system includes a substrate power source  52  coupled to the process chamber  10 , and configured to couple power to the substrate holder  20 . The substrate power source  52  contains a RF generator and an impedance match network. The substrate power source  52  is configured to couple power to the first process material, or the second process material, or both, in the processing space  70  by energizing an electrode  28  in the substrate holder  20 . A typical frequency for the RF bias can range from about 0.1 MHz to about 100 MHz, and can be 13.56 MHz. RF bias systems for plasma processing are well known to those skilled in the art. Alternatively, RF power is applied to the electrode  28  at multiple frequencies. 
     The film deposition system  1  contains a substrate temperature control system  60  coupled to the substrate holder  20  and configured to elevate, lower, and control the temperature of substrate  25 . The substrate temperature control system  60  is coupled to a resistive heating element  35  in the substrate holder  20 . The substrate temperature control system  60  can further contain temperature control elements, such as a cooling system including a re-circulating coolant flow that receives heat from the substrate holder  20  and transfers heat to a heat exchanger system (not shown). Additionally, the temperature control elements can include heating/cooling elements which can be included in the substrate holder  20 , as well as the chamber wall of the process chamber  10  and any other component within the film deposition system  1 . 
     In order to improve the thermal transfer between the substrate  25  and the substrate holder  20 , the substrate holder  20  can include a mechanical clamping system, or an electrical clamping system, such as an electrostatic clamping system, to affix the substrate  25  to an upper surface of substrate holder  20 . Furthermore, the substrate holder  20  can further include a substrate backside gas delivery system configured to introduce gas to the backside of substrate  25  in order to improve the gas-gap thermal conductance between the substrate  25  and the substrate holder  20 . Such a system can be utilized when good temperature control of the substrate  25  is required at elevated or reduced temperatures. For example, the substrate backside gas system can contain a two-zone gas distribution system, wherein the helium gas gap pressure can be independently varied between the center and the edge of the substrate  25 . 
     Furthermore, the process chamber  10  is coupled to a pressure control system  34  that includes a vacuum pumping system and a variable gate valve for controllably evacuating the process chamber  10  to a pressure suitable for processing the substrate  25 , and suitable for use of the first and second process materials. The vacuum pumping system can include a turbo-molecular vacuum pump (TMP) or a cryogenic pump capable of a pumping speed up to about 5000 liters per second (and greater). In conventional plasma processing devices utilized for thin film deposition or dry etching, a 300 to 5000 liter per second TMP is generally employed. Moreover, a device for monitoring chamber pressure, for example a capacitance manometer (not shown) can be coupled to the process chamber  10 . 
     The film deposition system  1  contains a controller  55  that is coupled to the process chamber  10 , pressure control system  34 , first process material supply system  40 , second process material supply system  42 , purge gas supply system  44 , first power source  50 , substrate power source  52 , actuator  58 , substrate temperature control system  60 , and substrate transfer system  505 . In addition, the controller  55  can be coupled to one or more additional controllers/computers (not shown), and the controller  55  can obtain setup and/or configuration information from an additional controller/computer. The controller  55  can be used to configure, collect, provide, process, store, and display data from the film deposition system  1 . The controller  55  can contain a number of applications for controlling the film deposition system  1 . For example, controller  55  can include a graphic user interface (GUI) component (not shown) that can provide easy to use interfaces that enable a user to monitor and/or control the film deposition system  1 . 
     The controller  55  can contain a microprocessor, memory, and a digital I/O port capable of generating control voltages sufficient to communicate and activate inputs to the film deposition system  1  as well as monitor outputs from the film deposition system  1 . For example, a program stored in the memory may be utilized to activate the inputs of the film deposition system  1  according to a process recipe in order to perform a film deposition process. The controller  55  may be implemented as a general purpose computer system that performs a portion or all of the microprocessor based processing steps of the invention in response to a processor executing one or more sequences of one or more instructions contained in a memory. Such instructions may be read into the controller memory from another computer readable medium, such as a hard disk or a removable media drive. One or more processors in a multi-processing arrangement may also be employed as the controller microprocessor to execute the sequences of instructions contained in main memory. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions. Thus, embodiments are not limited to any specific combination of hardware circuitry and software. 
     The controller  55  includes at least one computer readable medium or memory, such as the controller memory, for holding instructions programmed according to the teachings of the invention and for containing data structures, tables, records, or other data that may be necessary to implement embodiments of the invention. Stored on any one or on a combination of computer readable media, the present invention includes software for controlling the controller  55 , for driving a device or devices for implementing embodiments of the invention, and/or for enabling the controller to interact with a human user. Such software may include, but is not limited to, device drivers, operating systems, development tools, and applications software. Such computer readable media further includes the computer program product of the present invention for performing all or a portion (if processing is distributed) of the processing performed in implementing embodiments of the invention. 
       FIG. 6  is a schematic diagram of a processing system containing a non-ionizing electromagnetic radiation source for performing an oxidation process according to one embodiment of the invention. The radiation source can be a UV radiation source or a visible light radiation source, for example. The processing system  101  contains a process chamber  110  having a substrate holder  120  configured to support a substrate  125 . The process chamber  110  further contains an electromagnetic radiation assembly  130  for exposing the substrate  125  to electromagnetic radiation. Additionally, the processing system  101  contains a power source  150  coupled to the electromagnetic radiation assembly  130 , and a substrate temperature control system  160  coupled to substrate holder  120  and configured to elevate and control the temperature of substrate  125 . A gas supply system  140  is coupled to the process chamber  110 , and configured to introduce a process gas to process chamber  110 . For example, the process gas can include an oxygen-containing gas or an oxygen- and nitrogen-containing gas and optionally an inert gas such as a noble gas (i.e., helium, neon, argon, xenon, krypton). According to one embodiment of the invention, the process gas consists of O 2 . Additionally (not shown), a purge gas can be introduced to process chamber  110 . The purge gas may contain an inert gas, such as nitrogen or a noble gas. 
     The electromagnetic radiation assembly  130  can, for example, contain an ultraviolet (UV) radiation source. The UV source may be monochromatic or polychromatic. Additionally, the UV source can be configured to produce UV radiation  145  at a wavelength sufficient for dissociating an oxygen-containing gas or an oxygen- and nitrogen-containing gas in the process gas. In one embodiment, the oxygen-containing gas can contain O 2  and the ultraviolet radiation can have a wavelength from about 145 nm to about 192 nm. Other wavelength may be used for other oxygen-containing gases or oxygen- and nitrogen-containing gases. The electromagnetic radiation assembly  130  can operate at a power ranging from about 5 mW/cm 2  to about 50 mW/cm 2 . The electromagnetic radiation assembly  130  can include one, two, three, four, or more radiation sources. The sources can include lamps or lasers or a combination thereof. 
     The processing system  101  contains a substrate temperature control system  160  coupled to the substrate holder  120  and configured to elevate and control the temperature of substrate  125 . Substrate temperature control system  160  contains temperature control elements, such as a heating system that may contain resistive heating elements, or thermo-electric heaters/coolers. Additionally, substrate temperature control system  160  may contain a cooling system including a re-circulating coolant flow that receives heat from substrate holder  120  and transfers heat to a heat exchanger system (not shown), or when heating, transfers heat from the heat exchanger system. Furthermore, the substrate temperature control system  160  may include temperature control elements disposed in the chamber wall of the process chamber  110  and any other component within the processing system  101 . 
     Furthermore, the process chamber  110  is further coupled to a pressure control system  132 , including a vacuum pumping system  134  and a valve  136 , through a duct  138 , wherein the pressure control system  132  is configured to controllably evacuate the process chamber  110  to a pressure suitable for processing the substrate  125 . Moreover, a device for monitoring chamber pressure (not shown) can be coupled to the process chamber  110 . 
     Additionally, the processing system  101  contains a controller  170  coupled to the process chamber  110 , vacuum pumping system  134 , gas supply system  140 , power source  150 , and substrate temperature control system  160 . Alternatively, or in addition, controller  170  can be coupled to a one or more additional controllers/computers (not shown), and controller  170  can obtain setup and/or configuration information from an additional controller/computer. 
     The controller  170  can contain a microprocessor, memory, and a digital I/O port capable of generating control voltages sufficient to communicate and activate inputs to processing system  101  as well as monitor outputs from processing system  101 . For example, a program stored in the memory may be utilized to activate the inputs to the aforementioned components of the processing system  101  according to a process recipe in order to perform process. 
     Oxidation of a silicon nitride film in the processing system  101  can include a substrate temperature between about 200° C. and about 800° C., for example about 700° C. Alternatively, the substrate temperature can be between about 400° C. and about 700° C. The pressure in the process chamber  110  can, for example, be maintained between about 100 mTorr and about 20 Torr, for example about 100 mTorr. Alternatively, the pressure can be maintained between about 20 mTorr and about 1 Torr. According to one embodiment of the invention, the process gas consists of O 2  that may be introduced into the process chamber  110  at a flow rate between about 100 standard cubic centimeters per minute (sccm) and about 2 slm. According to another embodiment of the invention, the process gas can consist of O 2  and an inert gas such as a noble gas (i.e., helium, neon, argon, xenon, krypton). A flow rate of the inert gas can, for example, be between 0 slm and about 2 slm, or between 0.1 slm and 1 slm. In one example, the process gas consists of O 2  and Ar. Exemplary gas exposure times are between about 10 seconds and about 5 min, or between about 30 seconds and about 2 minutes, for example about 1 minute. 
       FIG. 7  is a schematic diagram of another processing system containing a non-ionizing radiation source for performing an oxidation process according to one embodiment of the invention. The radiation source can be a UV radiation source or a visible light radiation source, for example. The processing system  550  includes a process chamber  581  accommodating therein a rotatable substrate holder  582  equipped with a heater  583  that can be a resistive heater. Alternatively, the heater  583  may be a lamp heater or any other type of heater. Furthermore the process chamber  581  contains an exhaust line  590  connected to the bottom portion of the process chamber  581  and to a vacuum pump  587 . The substrate holder  582  can be rotated by a drive mechanism (not shown). The process chamber  581  contains a processing space  586  above the substrate  525 . The inner surface of the process chamber  581  contains an inner liner  584  made of quartz in order to suppress metal contamination of the substrate  525  to be processed. 
     The process chamber  581  contains a gas line  588  with a nozzle  589  located opposite the exhaust line  590  for flowing a process gas containing an oxygen-containing gas or an oxygen- and nitrogen-containing gas over the substrate  525 . The process gas flows over the substrate  525  in a processing space  586  and is evacuated from the process chamber  581  by the exhaust line  590 . 
     The process gas supplied from the nozzle  589  is activated by non-ionizing electromagnetic radiation  595  generated by an electromagnetic radiation source  591  emitting non-ionizing electromagnetic radiation  595  through a transmissive window  592  (e.g., quartz) into the processing space  586  between the nozzle  589  and the substrate  525 . The electromagnetic radiation source  591  is configured to generate non-ionizing electromagnetic radiation  595  capable of dissociating the oxygen-containing gas or the oxygen- and nitrogen-containing gas to form neutral O radicals that flow along the surface of the substrate  100 , thereby exposing the substrate  525  to the neutral O radicals. Unlike during plasma processing, substantially no ions are formed in the processing space  586  from dissociation of the oxygen-containing gas or oxygen- and nitrogen-containing gas by the UV radiation  595 . According to one embodiment of the invention, the electromagnetic radiation source  591  is configured to generate UV radiation with a wavelength between about 145 nm to about 192 nm, for example 172 nm. Although only one electromagnetic radiation source  591  is depicted in  FIG. 7 , other embodiments of the invention contemplate the use of a plurality of electromagnetic radiation sources  591  above the substrate  525 . 
     Furthermore, the process chamber  581  contains a remote RF plasma source  593  located opposite the exhaust line  590 . The remote RF plasma source  593  may be utilized to form neutral and ionized plasma-excited species that may assist in the non-ionizing electromagnetic radiation-assisted oxidation process described above. A second process gas containing an oxygen-containing gas or an oxygen- and nitrogen-containing gas can be supplied by gas line  594  to the remote RF plasma source  593  for forming the plasma-excited oxidation species. The plasma-excited oxidation species flow from the remote RF plasma source  593  along the surface of the substrate  525 , thereby exposing the substrate  525  to the plasma-excited oxidation species. According to one embodiment of the invention, in addition to exposing the substrate  525  to neutral O radicals generated by the electromagnetic radiation source  591 , the substrate may be exposed to oxygen radicals generated by the remote RF plasma source  593  and transported to the processing space  586 . 
     Still referring to  FIG. 7 , a controller  599  includes a microprocessor, a memory, and a digital I/O port capable of generating control voltages sufficient to communicate and activate inputs of the processing system  550  as well as monitor outputs from the processing system  550 . Moreover, the controller  599  is coupled to and exchanges information with process chamber  581 , the vacuum pump  587 , the heater  583 , the remote RF plasma source  593 , and the electromagnetic radiation source  591 . The controller  599  may be implemented as a UNIX-based workstation. Alternatively, the controller  599  can be implemented as a general-purpose computer, digital signal processing system, etc. 
     Further details of a processing system containing an UV radiation source are described in U.S. Pat. No. 6,927,112, titled “Radical Processing Of A Sub-Nanometer Insulation Film”, the entire contents of which is hereby incorporated by reference. 
     Oxidation of a silicon nitride film in the processing system  550  can include a substrate temperature between about 200° C. and about 800° C., for example about 700° C. Alternatively, the substrate temperature can be between about 400° C. and about 700° C. The pressure in the process chamber  110  can, for example, be maintained between about 100 mTorr and about 20 Torr, for example about 100 mTorr. Alternatively, the pressure can be maintained between about 20 mTorr and about 1 Torr. According to one embodiment of the invention, the process gas consists of O 2  that may be introduced into the process chamber  581  at a flow rate between about 100 sccm and about 2 slm. According to another embodiment of the invention, the process gas can consist of O 2  and an inert gas such as a noble gas. A flow rate of the inert gas can, for example, be between 0 sccm and about 2 slm. In one example, the process gas consists of O 2  and Ar. Exemplary gas exposure times are between about 10 sec and about 5 min, for example about 1 min. 
       FIG. 8  is a schematic diagram of a plasma processing system containing a slot plane antenna (SPA) plasma source for performing an oxidation process according to one embodiment of the invention. The plasma produced in the plasma processing system  410  is characterized by low electron temperature and high plasma density that enables damage-free oxidation of silicon nitride films according to embodiments of the invention. The plasma processing system  410  can, for example, be a TRIAS™ SPA processing system from Tokyo Electron Limited, Akasaka, Japan. The plasma processing system  410  contains a process chamber  450  having an opening portion  451  in the upper portion of the process chamber  450  that is larger than a substrate  425 . A cylindrical dielectric top plate  454  made of quartz or aluminum nitride or aluminum oxide is provided to cover the opening portion  451 . Gas lines  472  are located in the side wall of the upper portion of process chamber  450  below the top plate  454 . In one example, the number of gas lines  472  can be 16 (only two of which are shown in  FIG. 8 ). Alternatively, a different number of gas lines  472  can be used. The gas lines  472  can be circumferentially arranged in the process chamber  450 , but this is not required for the invention. A process gas can be evenly and uniformly supplied into the plasma region  459  in process chamber  450  from the gas lines  472 . The process gas can contain an oxygen-containing gas (e.g., O 2 , H 2 O, or H 2 O 2 ), an oxygen- and nitrogen-containing gas (e.g., NO, N 2 O, or NO 2 ), or a combination thereof. The process gas can further contain an inert gas such as Ar. 
     In the plasma processing system  410 , microwave power is provided to the process chamber  450  through the top plate  454  via a slot plane antenna  460  having a plurality of slots  460 A. The slot plane antenna  460  faces the substrate  425  to be processed and the slot plane antenna  460  can be made from a metal plate, for example copper. In order to supply the microwave power to the slot plane antenna  460 , a waveguide  463  is disposed on the top plate  454 , where the waveguide  463  is connected to a microwave power supply  461  for generating microwaves with a frequency of about 2.45 GHz, for example. The waveguide  463  contains a flat circular waveguide  463 A with a lower end connected to the slot plane antenna  460 , a circular waveguide  463 B connected to the upper surface side of the circular waveguide  463 A, and a coaxial waveguide converter  463 C connected to the upper surface side of the circular waveguide  463 B. Furthermore, a rectangular waveguide  463 D is connected to the side surface of the coaxial waveguide converter  463 C and the microwave power supply  461 . 
     Inside the circular waveguide  463 B, an axial portion  462  of an electroconductive material is coaxially provided, so that one end of the axial portion  462  is connected to the central (or nearly central) portion of the upper surface of slot plane antenna  460 , and the other end of the axial portion  462  is connected to the upper surface of the circular waveguide  463 B, thereby forming a coaxial structure. As a result, the circular waveguide  463 B is constituted so as to function as a coaxial waveguide. The microwave power can, for example, be between about 0.5 W/cm 2  and about 4 W/cm 2 . Alternatively, the microwave power can be between about 0.5 W/cm 2  and about 3 W/cm 2 . The microwave irradiation may contain a microwave frequency of about 300 MHz to about 10 GHz and the plasma may contain an electron temperature of less than about 3 eV, which includes 0.1, 0.3, 0.5, 0.7, 0.9, 1, 1.5, 2, 2.5, or 3 eV, or any combination thereof. The plasma may have a density of about 1×10 11 /cm 3  to about 1×10 13 /cm 3 , or higher. 
     In addition, in the process chamber  450 , a substrate holder  452  is provided opposite the top plate  454  for supporting and heating a substrate  425  (e.g., a wafer). The substrate holder  452  contains a heater  457  to heat the substrate  425 , where the heater  457  can be a resistive heater. Alternatively, the heater  457  may be a lamp heater or any other type of heater. Furthermore the process chamber  450  contains an exhaust line  453  connected to the bottom portion of the process chamber  450  and to a vacuum pump  455 . 
     Still referring to  FIG. 8 , a controller  499  includes a microprocessor, a memory, and a digital I/O port capable of generating control voltages sufficient to communicate and activate inputs of the plasma processing system  410  as well as monitor outputs from the plasma processing system  410 . Moreover, the controller  499  is coupled to and exchanges information with process chamber  450 , the vacuum pump  455 , the heater  457 , and the microwave power supply  461 . A program stored in the memory is utilized to control the aforementioned components of plasma processing system  410  according to a stored process recipe. One example of controller  499  is a UNIX-based workstation. Alternatively, the controller  499  can be implemented as a general-purpose computer, digital signal processing system, etc. 
     Oxidation of a silicon nitride film in the plasma processing system  410  can include a substrate temperature between about 25° C. and about 800° C., for example about 400° C. Alternatively, the substrate temperature can be between about 400° C. and about 700° C. The pressure in the process chamber  450  can, for example, be maintained between about 10 mTorr and about 10 Torr, for example about 100 mTorr. Alternatively, the pressure can be maintained between about 20 mTorr and about 1 Torr. According to one embodiment of the invention, the process gas consists of O 2  that may be introduced into the process chamber  581  at a flow rate between about 5 sccm and about 1 slm. According to another embodiment of the invention, the process gas can consist of O 2  and an inert gas such as a noble gas. A flow rate of the inert gas can, for example, be between 0 sccm and about 5 slm. In one example, the process gas consists of O 2  and Ar. Exemplary gas exposure times are between about 5 sec and about 5 min, for example about 20 sec. 
     A plurality of embodiments for depositing silicon nitride films and subsequently forming stressed silicon oxynitride films have been described. The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. This description and the claims following include terms that are used for descriptive purposes only and are not to be construed as limiting. For example, the term “on” as used herein (including in the claims) does not require that a film “on” a substrate is directly on and in immediate contact with the substrate; there may be a second film or other structure between the film and the substrate. 
     Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above teaching. Persons skilled in the art will recognize various equivalent combinations and substitutions for various components shown in the Figures. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.