Patent Application
20060000806
Embodiments of the present invention relate to a substrate carrier adapted to enhance substrate surface planarization in processes such as chemical mechanical planarization (CMP).
Embodiments of the present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments in accordance with the present invention is defined by the appended claims and their equivalents.
Embodiments of the present invention relate to the processing of substrates such as semiconductor wafers and/or metalized layers in semiconductor devices, using a substrate carrier configured to provide localized control of surface planarization during a CMP process. Embodiments of the present invention may allow for the processing of a substrate using, for example, very low pressures, high rotational velocity, and manipulation of other parameters that may be particularly useful for planarization of ultra low-K substrates to help resist mechanical damage during the substrate processing step.
Substrate carrier 20 may be configured to support a substrate 22 in a substantially opposing relationship with the processing element 16 (processing relationship). Substrate carrier 20 may also be adapted to movably position the substrate 22 in an urging engagement with the processing element 16 to effect a planarization or polishing of the process side 24 of substrate 22. Substrate carrier 20 may be configured to rotate, oscillate, or otherwise move as needed to induce processing of the process side 24 of substrate 22.
Slurry delivery system 12 may include one or more nozzles 27 positioned adjacent the surface 18 of processing element 16 for the dispensing of a slurry/solution 28 thereon. During a polishing/planarization step, for example, a slurry 28 containing a liquid, such as, but not limited to, deionized water for oxide polishing and a pH adjuster, such as potassium hydroxide also for oxide polishing, can be supplied to the surface 18 of processing element 16 by the slurry arm 12, and may help facilitate removal of material from process side 24 of substrate 22. Slurry 28 can also include abrasive particles, including, but not limited to, silicon dioxide for oxide polishing.
Substrate carrier 20 may also include an array of actuators 32 disposed within the body of housing 26, and in the illustrated embodiment may be disposed in cavity 28 of housing 26. Actuators 32 may be adapted to independently and controllably urge one or more localize portions of substrate 22 to be in respectively the same or different greater degrees of processing engagement with process element 16. The one or more localized deflections of the substrate may in turn enhance planarization at that point or points. Actuators 32 may take a number forms and be actuated or driven in several ways.
In one embodiment of the invention, actuators 32 may be electrically driven and include, for example, an impingement pin 34 that has a first end 40 and a second end 41. Impingement pin 34 may project from within cavity 28 through an actuator bore 36 in backing plate 44 in a linearly movable fashion. First end 40 may be configured for engagement with the backside 23 of substrate 22. A portion of the impingement pin 34 may also pass through a solenoid 38, such as an electrically conductive coil winding, also housed within cavity 28. Solenoid 38 may be configured to selectively move impingement pin 34 within actuator bore 36 by changing the current magnitude and/or flow through solenoid 38.
The solenoid 38 may be energized by a controllable electricity source 60, such that the current supplied to coil 34 may be varied. Applying a current may cause first end 40 of impingement pin 34 to push against backside 23 such that a local deflection of substrate 22 may result. Such a deflection may urge the process side of the localized deflection to be in greater contact with processing element 18 and thus may enhance the planarization of the localized area. Likewise, changing the current (e.g. reversing the current flow) may result in a retraction of impingement pin 34, which in turn may relive the deflection to reduce the enhanced planarization caused by the local deflection.
Controlling the deflections of certain substrate portions may provide for selective local control of material removal from the process side 24 of substrate 22. As illustrated in
In one embodiment of the present invention, controller 62 may include, but is not limited to, an electronic computer. The computer may include, a CPU, memory, buses, I/O ports all suitably interconnected to electricity source 60 and configured to control the linear actuation of impingement pin 34. In one embodiment of the invention, software instructions and data can be coded and stored within the memory for causing the controller 62 to generate suitable signals to each solenoid 38 to control the movement of the first end 40 of the impingement pin 34 into and out of forcible engagement with backside 23. In alternate embodiments, application specific integrated circuits (ASIC), or other special purpose hardware may be employed to implement controller 62.
In one embodiment of the present invention, an end point detection device 64 may also be in communication with controller 62, and configured to detect and/or monitor the processing of the process side 24 of substrate 22. End point detection device 64 may be a suitable device currently used.
During the processing of substrate 22, should a localized area of substrate 22 need more aggressive polishing, as may be determined by end point detection device 64, the end point detection device 64 may send a signal to controller 62. Controller 62 may in turn cause electricity source 60 to modify/change the current to solenoid 38 as needed to cause the first end 40 of impingement in 34 to increase engaging pressure against the backside 23. This increased pressure may generate localized deflection 48, which in turn may enhance localized planarization of substrate 22. Upon reaching a desired planarization, again as may be detected by end point detection device 64, the reverse process may occur such that the amount of deflection may be reduced to reduce the amount of localized planarization.
A plurality of actuators 400 (shown in both configurations A and B) may be positioned within cavity 248 of substrate carrier 420. Actuators 400 may be pneumatically driven, and include a movable piston 402 and a cylinder 404 that may be chargeable with air or other gas. Piston 402 may be configured to controllably slide in and out of cylinder 404 based on a signal input and a charging and exhausting of air from cylinder 404. Piston 402 may be configured to extend from cylinder 404 through actuator bore 436 in backing plate 444, and have a first end 440 configured for engagement with backside 423. Actuators 400 may be in communication with a pneumatic controller 460, which may selectively and independently control the actuation of pistons 402 by controlling the supply of air to individual pneumatic actuators 400 through supply lines 401.
CMP systems typically include a number of pneumatically operated subsystems and actions. Accordingly, in one embodiment, the pneumatic source to the pneumatic controller 460 may be from a general source responsible for those other pneumatic operations. In one embodiment, an independent pneumatic source, such as a compressor or pressurized cylinder, may be in communication with pneumatic controller 460 and may also be incorporated in the substrate carrier 420.
To urge enhanced removal of material from a localized area of the process side 424 of substrate 422, pneumatic controller 460 may activate pneumatic actuator 400, such that piston 402 is forced out of cylinder 404, first end 440 may be urged against backside 423 of substrate 422. Illustrated as pneumatic actuator configuration 400A, when piston 402 is in the extended position, it may cause a localized deflection 448 in substrate 422. Localized deflection 448 may enhance the removal of material at the area of deflection on the process side 424, as this area will be in a greater degree of contact with processing element 416.
In areas where material from the process side 424 does not need further removal, for example, the pneumatic actuator 400 may be in state where air from the cylinder 404 is removed such that piston 402 may at least partially retract into cylinder 404, as shown by pneumatic actuator configuration 400 B. With piston 402 retracted, there may be no affirmative substrate deflection, which in turn may de-emphasize contact between a localized area and process element 416. Piston 402 may be controllably retracted and extended between the range of movement 406, such that the amount of localized deflection 448 may be controlled anywhere from a maximum deflection state to a minimum or no deflection state, depending on the processing status.
An end point detector 462 may be utilized to monitor the planarization of the process side 424 of substrate 422. End point detection device 462 may generate signals corresponding to various planarization states, and be configured to send such signals to pneumatic controller 460. Depending on the state of planarization (uniformity, degree of material removal, overall planarization, etc.), pneumatic controller 462 may in turn selectively control actuation of the independent pneumatic actuators, and thus control the level of enhanced planarization and material removal at various localized areas on the process side 424.
In one embodiment of the invention, the actuator bores 436 may be configured to be controllably placed under a vacuum. Thus, when the actuators are not pushing against or in contact with the substrate backside 23, the substrate may be held against the backing plate at the localized area. Further, if desired, the vacuum may cause a localized inverse deflection in order to de-emphasize the removal of material in that localized area.
In embodiments of the present invention, additional actuators may be used having different actuation mechanisms, including, but not limited to a screw drive mechanism, hydraulic actuated systems, magnetically controlled systems, as well as other drive mechanisms that may allow for selective localized deflection of the substrate 422 to enhance material removal from localized areas. The number and configuration of actuators used in accordance with embodiments of the present invention may vary depending on a variety of factors, including the substrate material being processed (e.g. material composition, thickness, number of layers, etc.), the processing stage, substrate size, and the like.
Further, embodiments of the invention, actuators may be positioned within the processing element carrier and configured to create localized deflections in the processing element, such as a polishing pad. These localized deflections may enhance the amount of material removal on the process side of the substrate opposite the localized deflection in the process element.
The plurality of actuators may be selectively actuated to create localized deflections in the substrate (520). The removal of material from the process side of the substrate at the localized deflections may be controlled by selectively varying the amount of localized deflections and thus varying the amount and degrees of interaction between the localized deflections and the process element (530).
In one embodiment of the present invention, substrate surface pattern information, such as lithography mask information, may accompany the particular substrate or lot of substrates to be processed. This information may be used by the controller of the processing apparatus to independently and/or collectively manipulate the actuators to control the planarization of the process side in order to enhance the localized processing, for example within die, die-to-die and within substrate planarization.
In one embodiment of the present invention, the actuators may also be equipped with temperature modulating capability to modulate local surface temperatures of the processing side of the substrate. This may allow for the creation of a difference in temperature in a local area or from one grouping of localized areas to another area of the surface by individually and/or collectively controlling the temperature modulation, which in turn may to enhance or suppress local removal rates. For example, the actuator may increase or decrease the temperature at one or more localized areas or groups of localized areas, while the temperature at other localized locations may be maintained or independently modulated.
Embodiments of the present invention may allow for he energy sources may be manufactured in a number of ways. In one embodiment, the actuators may be manufactured using micro machining technology and methodologies, such as Micro Electro Machining Systems.
Though certain substrate processing tool configurations were illustrated, embodiments of the present invention may also be applied to a number of different processing tool configurations and processes. Other tool configurations may include, but are not limited to, those having single processing elements, multiple processing elements, processing elements having simple and complex geometries, substrate holders having one or more electrically isolated regions, and/or multiple substrate holders.
Although certain embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that embodiments in accordance with the present invention may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments in accordance with the present invention be limited only by the claims and the equivalents thereof.
