Abstract:
A mechanism for implementing at least one of activation and deactivation of a gas valve that is coupled to an input manifold of a processing chamber is provided. The mechanism includes a toggle arm disposed in one of a toggle activation position and a toggle deactivation position. The mechanism also includes a toggle operated switch coupled to the toggle arm and the gas valve. The toggle operated switch is disposed on top of the gas valve and the toggle arm is disposed on top of the toggle operated switch so as to minimize a footprint of an assembly that comprises the gas valve, the toggle operated switch, and the toggle arm. Thus, the process gas flow flows through the gas valve when the toggle arm is in the toggle activation position and is inhibited from flowing into the gas valve when the toggle arm is in the toggle deactivation position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This divisional application claims priority under 37 CFR 1.53(b) of and claims the benefit under 35 U.S.C. §120 to a commonly assigned patent application entitled “OPTIMIZED ACTIVATION PREVENTION MECHANISM FOR A GAS DELIVERY SYSTEM AND METHODS THEREFOR” by Mark Taskar, application Ser. No. 12/611,790 filed on Nov. 3, 2009, which claims priority from the U.S. Application entitled “Optimized Activation Prevention Assembly For A Gas Delivery System and Methods Therefore,” by Mark Taskar, application Ser. No. 11/165,858 filed on Jun. 24, 2005, which claims priority from the U.S. Provisional Application No. 60/689,390 entitled “OPTIMIZED LOCKOUT/TAGOUT ASSEMBLY FOR A GAS DELIVERY SYSTEM” by inventor Mark Taskar (filed Jun. 10, 2005, all of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates in general to substrate manufacturing technologies and in particular to an optimized activation prevention assembly for a gas delivery system, and methods therefor. 
     In the processing of a substrate, e.g., a semiconductor wafer, MEMS device, or a glass panel such as one. used in flat panel display manufacturing, plasma is often employed. As part of the processing of a substrate (chemical vapor deposition, plasma enhanced chemical vapor deposition, physical vapor deposition, etch, etc.) for example, the substrate is divided into a plurality of dies, or rectangular areas, each of which will become an integrated circuit. The substrate is then processed in a series of steps in which materials are selectively removed (etching) and deposited (deposition) in order to form electrical components thereon. 
     In a first exemplary plasma process, a substrate is coated with a thin film of hardened emulsion (such as a photoresist mask) prior to etching. Areas of the hardened emulsion are then selectively removed, causing parts of the underlying layer to become exposed. The substrate is then placed in a plasma processing chamber on a substrate support structure comprising a mono-polar or bi-polar electrode, called a chuck. Appropriate etchant source gases (e.g., C4F8, C4F6, CHF3, CH2F3, CF4, CH3F, C2F4, N2, O2, Ar, Xe, He, H2, NH3, SF6, BC13, C12, etc.) are then flowed into the chamber and struck to form a plasma to etch exposed areas of the substrate. 
     In general, there are three types of etch processes: pure chemical etch, pure physical etch, and reactive ion etch. Pure chemical etching generally involves no physical bombardment, but rather a chemical interaction with materials on the substrate. The chemical reaction rate could be very high or very low, depending on the process. For example, fluorine-based molecules tend to chemically interact with dielectric materials on the substrate, wherein oxygen-based molecules tend to chemically interact with organic materials on the substrate, such as photoresist. 
     Pure ion etching is often called sputtering. Usually an inert gas, such as Argon, is ionized in a plasma and used to dislodge material from the substrate. That is, positively charged ions accelerate toward a negatively charged substrate. Pure ion etching is both isotropic (i.e., principally in one direction) and non-selective. That is, selectivity to a particular material tends to be very poor, since the direction of the ion bombardment is mostly perpendicular to the substrate surface in plasma etch process. In addition, the etch rate of the pure ion etching is commonly low, depending generally on the flux and energy of the ion bombardment. 
     Etching that combines both chemical and ion processes is often called reactive ion etch (RIE), or ion assist etch. Generally ions in the plasma enhance a chemical process by striking the surface of the substrate, and subsequently breaking the chemical bonds of the atoms on the surface in order to make them more susceptible to reacting with the molecules of the chemical process. Since ion etching is mainly perpendicular, while the chemical etching is both perpendicular and vertical, the perpendicular etch rate tends to be much faster than in then horizontal direction. In addition, RIE tends to have an anisotropic profile. 
     However, because plasma processing system operation may also be dangerous (i.e., poisonous gases, high voltages, etc.), worker safety regulations often mandate that plasma processing manufacturing equipment include activation prevention capability, such as a lockout/tagout mechanism. Generally a lockout is a device that uses positive means such as a lock, either key or combination type, to hold an energy-isolating device in a safe position, thereby preventing the energizing of machinery or equipment. For example, when properly installed, a blank flange or bolted slip blind are considered equivalent to lockout devices. 
     A tagout device is generally any prominent warning device, such as a tag and a means of attachment, that can be securely fastened to an energy-isolating device in accordance with an established procedure. The tag indicates that the machine or equipment to which it is attached is not to be operated until the tagout device is removed in accordance with the energy control procedure. An energy-isolating device is any mechanical device that physically prevents the transmission or release of energy. These include, but are not limited to, manually-operated electrical circuit breakers, disconnect switches, line valves, and blocks. For example, a device is generally capable of being locked out if it meets one of the following requirements: a) it is designed with a hasp to which a lock can be attached; b) it is designed with any other integral part through which a lock can be affixed; c) it has a locking mechanism built into it; or d) it can be locked without dismantling, rebuilding, or replacing the energy isolating device or permanently altering its energy control capability. 
     Referring now to  FIG. 1 , a simplified diagram of an inductively coupled plasma processing system is shown. Generally, an appropriate set of gases may be flowed from gas distribution system  122  into plasma chamber  102  having plasma chamber walls  117 . These plasma processing gases may be subsequently ionized at or in a region near injector  109  to form a plasma  110  in order to process (e.g., etch or deposit) exposed areas of substrate  114 , such as a semiconductor substrate or a glass pane, positioned with edge ring  115  on an electrostatic chuck  116 . 
     A first RF generator  134  generates the plasma as well as controls the plasma density, while a second RF generator  138  generates bias RF, commonly used to control the DC bias and the ion bombardment energy. Further coupled to source RF generator  134  is matching network  136   a , and to bias RF generator  138  is matching network  136   b,  that attempt to match the impedances of the RF power sources to that of plasma  110 . Furthermore, vacuum system  113 , including a valve  112  and a set of pumps  111 , is commonly used to evacuate the ambient atmosphere from plasma chamber  102  in order to achieve the required pressure to sustain plasma  110  and/or to remove process byproducts. 
     Referring now to  FIG. 2 , a simplified diagram of a capacitively coupled plasma processing system is shown. Generally, capacitively coupled plasma processing systems may be configured with a single or with multiple separate RF power sources. Source RF, generated by source RF generator  234 , is commonly used to generate the plasma as well as control the plasma density via capacitively coupling. Bias RF, generated by bias RF generator  238 , is commonly used to control the DC bias and the ion bombardment energy. Further coupled to source RF generator  234  and bias RF generator  238  is matching network  236 , which attempts to match the impedance of the RF power sources to that of plasma  220 . Other forms of capacitive reactors have the RF power sources and match networks connected to the top electrode  204 . In addition there are multi-anode systems such as a triode that also follow similar RF and electrode arrangements. 
     Generally, an appropriate set of gases is flowed through an inlet in a top electrode  204  from gas distribution system  222  into plasma chamber  202  having plasma chamber walls  217 . These plasma processing gases may be subsequently ionized to form a plasma  220 , in order to process (e.g., etch or deposit) exposed areas of substrate  214 , such as a semiconductor substrate or a glass pane, positioned with edge ring  215  on an electrostatic chuck  216 , which also serves as an electrode. Furthermore, vacuum system  213 , including a valve  212  and a set of pumps  211 , is commonly used to evacuate the ambient atmosphere from plasma chamber  202  in order to achieve the required pressure to sustain plasma  220 . 
     Since it is not uncommon to have over seventeen different gases coupled to a single plasma processing system, manufactures generally configure their gas delivery systems in high density flow component configurations called “gas sticks,” which may themselves be constructed in the form of a manifold assembly (i.e., stainless steel, etc.) attached to a substrate assembly. A gas flow control component generally needs only be attached to the manifold assembly on one side to complete the gas flow channels that are drilled into the manifold assembly itself. 
     Referring now to  FIG. 3 , a simplified diagram of gas stick is shown. In a common configuration, a gas cylinder (not shown) is coupled to an inlet valve  302 , which allows an operator to shut off any source gas flow into the stick. In some configurations, inlet valve  302  is manually operated. In other configurations, inlet valve  302  is pneumatically operated. That is, inlet valve  302  is operated by a compressed gas, such as compressed air. In addition, although as previously stated, it is often mandated that plasma processing systems have lockout/tagout functionality, it is not generally common to integrate lockout/tagout functionality into inlet valve  302  because of space limitations within the gas distribution system. 
     Inlet valve  302  may be further coupled to regulator/transducer  304  that substantially maintains a constant pressure to mass flow controller  308 , which may be attached to primary shutoff valve  312 , which generally allows gas flow in the gas stick to be blocked. Optionally, filter  306  is placed between regulator/transducer  304  and primary shutoff valve  312  to remove any particulates that may have entered the gas stream. In addition, a purge valve  310  is generally located between primary shutoff valve  312  and mass flow controller  308 . Mass flow controller  308  is generally a self-contained device (consisting of a transducer, control valve, and control and signal-processing electronics) commonly used to measure and regulate the mass flow of gas to the plasma processing system. 
     Further coupled to mass flow controller  308 , and generally not included in the gas stick itself, is a mixing manifold  314  that generally combines the gas flows from each of the appropriate gas sticks and channels the mixed gases into plasma chamber  318  through injector  316 . 
     However, the density of flow components to each other in a gas distribution system also tends to make individual gas stick activation prevention problematic, particularly at a gas stick inlet valve. In a typical configuration, all the plasma gases must generally be turned off and then vented, should an employee wish to physically access the gas distribution system, for example, as part of the tool assembly process, or in order to integrate the plasma processing system with a customer fabrication facility. This venting process may be further aggravated since the plasma gas shutoff for the gas feed into the inlet valve (prior to entering the gas stick) may not be physically located at the plasma processing system. Hence, an employee may either need to waste time traveling to the plasma gas shutoff location, or the employee may need to coordinate with another employee do the same. It would thus be advantageous to quickly and safely turn off a single gas stick in order to debug a problem or test a gas flow. 
     In view of the foregoing, there are desired an optimized activation prevention assembly for a gas delivery system and methods therefor. 
     SUMMARY OF THE INVENTION 
     The invention relates, in an embodiment, to an optimized activation prevention assembly for a gas delivery system. The apparatus includes a pneumatically operated valve assembly. The apparatus also includes a toggle switch mechanically attached to the pneumatically operated valve assembly, the toggle switch includes a toggle arm, the toggle arm being positioned in one of an activation zone and a deactivation zone, wherein when the toggle arm is positioned in the activation zone, the pneumatically operated valve is activated, and wherein when the toggle arm is positioned in the deactivation zone, the pneumatically operated valve is deactivated. The apparatus further includes an activation prevention mechanism attached to the toggle switch, wherein when the activation prevention mechanism being configured for preventing the toggle arm from being repositioned from the deactivation zone to the activation zone without at least bypassing a lockout function of the optimized activation prevention mechanism. 
     The invention relates, in an embodiment, to a method of preventing the activation of a pneumatically operated valve assembly in a gas delivery system. The method includes providing the pneumatically operated valve assembly. The method also includes attaching a toggle switch to the pneumatically operated valve assembly, the toggle switch including a toggle arm, the toggle arm being positioned in one of an activation zone and a deactivation zone, the toggle switch further configured such that when the toggle switch is positioned in the activation zone, the pneumatically operated valve is activated, and wherein when the toggle arm is positioned in the deactivation zone, the pneumatically operated valve is deactivated. The method further includes attaching an activation prevention mechanism to the toggle switch, the activation prevention mechanism being configured for preventing the toggle arm from being repositioned from the deactivation zone to the activation zone without at least bypassing a lockout function of the optimized activation prevention mechanism. 
     The invention relates, in an embodiment, to an apparatus for preventing the activation of a pneumatically operated valve assembly in a gas delivery system. The apparatus includes a means for providing the pneumatically operated valve assembly. The apparatus also includes a means for attaching a toggle switch to the pneumatically operated valve assembly, the toggle switch including a toggle arm, the toggle arm being positioned in one of an activation zone and a deactivation zone, the toggle switch further configured such that when the toggle switch is positioned in the activation zone, the pneumatically operated valve is activated, and wherein when the toggle arm is positioned in the deactivation zone, the pneumatically operated valve is deactivated. The apparatus further includes a means for attaching an activation prevention mechanism to the toggle switch, the activation prevention mechanism being configured for preventing the toggle arm from being repositioned from the deactivation zone to the activation zone without at least bypassing a lockout function of the optimized activation prevention mechanism. 
     These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
         FIG. 1  illustrates a simplified diagram of an inductively coupled plasma processing system; 
         FIG. 2  illustrates a simplified diagram of a capacitively coupled plasma processing system; 
         FIG. 3  illustrates a simplified diagram of gas stick; 
         FIG. 4  illustrates a simplified lockout/tagout procedure, according to one embodiment of the invention; 
         FIG. 5  illustrates a simplified diagram of an optimized activation prevention assembly integrated into a pneumatically operated valve, according to one embodiment of the invention; 
         FIG. 6  illustrates a simplified set of diagrams of an optimized activation prevention assembly, according to one embodiment of the invention; and 
         FIG. 7  illustrates a simplified method of preventing the activation of a pneumatically operated valve assembly in a gas delivery system, according to one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention. 
     In general, as previously described, worker safety regulations often mandate that plasma processing manufacturing equipment include activation prevention capability, such as a lockout/tagout mechanism. Generally a lockout is a device that uses positive means such as a lock, either key or combination type, to hold an energy-isolating device in a safe position. A tagout device is generally any prominent warning device, such as a tag and a means of attachment that can be securely fastened to energy-isolating device in accordance with an established procedure. 
     However, gas stick density tends to make individual gas stick activation prevention problematic, particularly at a gas stick inlet valve. In a non-obvious way, unlike commonly used gas stick lockout/tagout techniques of directly blocking plasma gas flow with a manual valve (energy-isolating device), the current invention indirectly blocks plasma gas flow by manually deactivating a pneumatically operated valve. That is, manually blocking compressed gas flow to a pneumatically operated valve causes the valve to become deactivated (closed), which in turn effectively stops plasma gas flow within the gas stick. Thus, the integration of a lockout/tagout mechanism with a pneumatically operated valve may allow gas stick component density to be maintained, while substantially improving employee safety by allowing each gas stick to be individually and quickly locked and/or tagged. 
     In an embodiment, an optimized activation prevention assembly is advantageously employed on a gas stick inlet valve. In an embodiment, the optimized activation prevention assembly includes a lockout mechanism. In an embodiment, the optimized activation prevention assembly includes a tagout mechanism. A lockout mechanism generally allows a lock to be attached in order to place a device in a safe position, while a tagout mechanism may notify an employee as to the presence of the lock. 
     Although usually mandated by regulation, this invention does not require that both the lock and the tag be simultaneously added to the optimized activation prevention assembly. In an embodiment, the optimized activation prevention assembly is integrated into a manual gas stick inlet valve. In an embodiment, the optimized activation prevention assembly is integrated into a pneumatically operated valve, such that engaging the lockout/tagout mechanism of the optimized activation prevention assembly blocks compressed gas from activating the pneumatically operated valve. In an embodiment, the pneumatically operated valve is an IGS (integrated gas system) valve. 
     Referring now to  FIG. 4 , a simplified lockout/tagout procedure is shown, according to one embodiment of the invention. At step  402 , the plasma processing system is prepared for shutdown. Next, at step  404 , the plasma processing system is actually shut down. Next, at step  406 , the plasma processing system is isolated from the gas source (e.g., by shutting the inlet valve, etc.). Next, at step  408 , the lockout/tagout device is added to the energy-isolating device (e.g., inlet valve, etc.). Next, at step  410  all potentially hazardous stored or residual energy is safely released (e.g., by venting any gas in the plasma stick, etc.). Finally at step  412 , the isolation of the plasma processing system from the gas source is verified prior to the start of service or maintenance work. 
     Referring now to  FIG. 5 , a simplified diagram of a optimized activation prevention assembly integrated into a pneumatically operated valve is shown, according to an embodiment of the invention. In an embodiment, the valve is an integrated surface mount valve. In general, an integrated surface mount component is a gas control component (e.g., valve, filter, etc.) that is connected to other gas control components through channels on a substrate assembly, upon which the gas control components are mounted. This is in contrast to gas control components that are generally attached through bulky conduits with VCR attachments (vacuum coupled ring). 
     In an embodiment, the valve is a gas stick inlet valve. In an embodiment, the valve is an IGS valve. Mounted on a substrate assembly (not shown) is typically a manifold assembly  502  to which pneumatically operated valve  506  is attached through an adapter  504 . In an embodiment, adapter  504  is threaded. In a typical configuration, a pressure coupling  508  allows a compressed gas line (not shown) to be attached to pneumatically operated valve  506  through adapter-fitting  510 . That is, as compressed air enters pneumatically operated valve  506  through adapter-fitting  510 , a valve mechanism is engaged and gas is allowed to flow in the gas stick. 
     In an embodiment, adapter  510  is threaded. Further attached to adapter  510  is a manual shutoff switch  512  and lockout/tagout mechanism  514 . When manual shutoff switch  512  is engaged by toggle arm  516 , compressed gas is blocked causing pneumatically operated valve  506  to be deactivated, and stopping plasma gas flow within the gas stick. In addition, the manual shutoff switch  512  may also contain an exhaust port allowing any compressed air that was in pneumatically operated valve  506 , prior to the engagement of manual shutoff switch  512 , to be vented. That is, the pressure within pneumatically operated valve  506  may be made substantially the same as the pressure outside pneumatically operated valve  506 . In addition, a lock and/or tag may thus be added to lockout/tagout mechanism  514 , in order to substantially insure the safe maintenance of the plasma processing system. In an embodiment, the optimized activation prevention assembly is configured to minimize early or accidental removal. That is, pneumatically operated valve  506  may not be activated without first removing the lock and/or tag, or else substantially damaging the optimized activation prevention assembly. In an embodiment, the lock is non-reusable. In an embodiment, the lock is attachable by hand. In an embodiment, the lock is self-locking. In an embodiment, the lock is non-releasable. In an embodiment, the tag is a one-piece nylon cable tie. In an embodiment, the tag states one of the following: “DO NOT START,” “DO NOT OPEN,” “DO NOT CLOSE,” “DO NOT ENERGIZE,” and “DO NOT OPERATE.” 
     Referring now to  FIG. 6 , a simplified set of top view and side view of lockout/tagout mechanism  514  of  FIG. 5  is shown, according to an embodiment of the invention. In general, a toggle arm, (e.g., toggle arm  516 ), may be inserted through cavity  608  wherein cavity  608  is disposed in a first portion  622  of lockout/tagout mechanism  514 ), such that toggle arm  516  is sandwiched between panels  604   a - b  (wherein panels are coupled with a second portion  624  of lockout/tagout mechanism  514 ). Second portion  624  is at a constant angle  610  to first portion  622 , angle  610  being between greater than 90 degrees and less than 180 degrees. Lockout/tagout mechanism  514  further includes a deactivation zone  614  and an activation zone  612 , such that when toggle arm  516  is positioned in deactivation zone  614  (deactivating pneumatically operated valve  506  as shown in  FIG. 5 ), and a lock is positioned through channels  605 - 606  and positioned a first position  626  determining a limit of deactivation zone  614  toggle arm  516  cannot be repositioned to activation zone  612  without bypassing lockout/tagout mechanism  514  (e.g., tearing panels  604   a - b , removing lock  602 , bending lockout/tagout mechanism  514 , etc.). A limit of activation zone  612  may be determined by a position  628  of lock  602 . 
     Referring now to  FIG. 7 , a simplified method of preventing the activation of a pneumatically operated valve assembly in a gas delivery system. Initially, at step  702 , a pneumatically operated valve assembly is provided. Next, at step  704 , a toggle switch is attached to the pneumatically operated valve assembly, the toggle switch including a toggle arm, the toggle arm being positioned in one of an activation zone and a deactivation zone. Finally, at step  706  an activation prevention mechanism is attached to the toggle switch. 
     While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. For example, although the present invention has been described in connection with Lam Research plasma processing systems (e.g., Exelan™, Exelan™ HP, Exelan™ HPT, 2300™, Versys™ Star, etc.), other plasma processing systems may be used. This invention may also be used with substrates of various diameters (e.g., 200 mm, 300 mm, etc.). In addition, any type of pneumatically operated valve may be used. It should also be noted that there are many alternative ways of implementing the methods of the present invention. 
     Advantages of the invention include the avoidance of cost related to non-optimized gas delivery systems, in which all the plasma gases must generally be turned off and then vented, should an employee wish to physically access the gas distribution system for maintenance, assembly, or integration. Additional advantages include allowing gas stick component density to be maintained, while substantially improving employee safety by allowing each gas stick to be individually and quickly locked and/or tagged. 
     Having disclosed exemplary embodiments and the best mode, modifications and variations may be made to the disclosed embodiments while remaining within the subject and spirit of the invention as defined by the following claims.