SURFACE PLANARIZATION SYSTEM AND METHOD

Abstract

A surface planarization system is presented. The system comprises an external energy source for generating a localized energy distribution within a processing region, and a control unit for operating the external energy source to create, by the localized energy distribution, a predetermined temperature pattern within the processing region such that different locations of the processing region are subjected to different temperatures. This provides that when a sample (e.g. semiconductor wafer) during its interaction with an etching material composition is located in the processing region, the temperature pattern at different locations of the sample's surface creates different material removal rates by the etching material composition (different etch rates).

Claims

1. A surface planarization system comprising: an external energy source for generating a localized energy distribution within a processing region, and a control unit for operating said external energy source to create, by said localized energy distribution, a predetermined temperature pattern within said processing region such that different locations of said processing region are subjected to different temperatures, providing that when a sample interacting with an etching material composition is located in said processing region, the temperature pattern at different locations of the sample's surface creates different material removal rates by said etching material composition.

2. The system according to claim 1, wherein said external energy source comprises one or more heaters.

3. The system according to claim 2, wherein said one or more heaters are configured for generating electromagnetic radiation.

4. The system according to claim 2, wherein said external energy source comprises a matrix of heaters arranged in a plane in a spaced-apart relationship, such that actuation of selective heaters with required working parameters creates said localized temperature distribution in the processing region.

5. The system according to claim 4, wherein the working parameters include at least one of the following: heating temperature, pulsed or CW operational mode, duration of heating, heating pulse shape, time pattern of heating pulses.

6. The system according to claim 1, wherein the control unit comprises a process controller utility comprising a data processor configured for receiving and processing input data and generating operation data to the energy source, said operation data being indicative of the temperature pattern to be produced by the energy source in the processing region.

7. The system according to claim 6, wherein said input data comprises a sample map corresponding to thickness profile of a layer on the sample, said data processor of the control unit being configured for processing said sample map data, determining a corresponding etch map, and generating said corresponding operation data to the energy source.

8. The system according to claim 6, wherein said input data comprises etch map data corresponding to a sample map indicative of thickness profile of a layer on the sample to be processed by the system.

9. The system according to claim 6, wherein the control unit is configured for communication with an external system for receiving said input data.

10. The system according to claim 1, comprising an in-situ metrology module configured for data communication with a control unit of the external energy source, said in-situ metrology module being configured and operable for measuring at least one parameter of the sample and etch material composition, and generating process control data to be used by the control unit for controlling working parameters of the energy source to maintain the required temperature pattern and to define end point of the planarization process for required result.

11. A surface planarization system comprising: an external energy source capable of generating a localized energy distribution within a processing region; a support unit for supporting a sample in an etching solution, in said processing region; and a control unit for receiving input data indicative of a sample map, determining a corresponding etch map, and generating operation data for operating said energy source to create the localized energy distribution creating a predetermined temperature pattern in said sample, thereby causing a temperature dependent etching pattern within the sample.

12. A processing system for processing samples progressing on a production line, the system comprising: a material removal system configured for applying at least one rough material removal process to a sample's surface; a surface planarization system configured for processing said sample after being processed by said material removal system, said surface planarization system being configured according to claim 1; and a metrology system configured for measuring on the sample and generating process control data enabling generation of operation data to said surface planarization system.

13. The processing system of claim 12, comprising an in-situ metrology module associated with the surface planarization system.

14. The processing system of claim 13, where said in-situ metrology module is configured and operable for: measuring at least one parameter, said at least parameter including at least one sample parameter and/or at least etch material composition parameter, and generating process control data for controlling working parameters of the energy source to maintain the required temperature pattern.

15. The processing system of claim 12, wherein said material removal system is configured for material removal by chemical mechanical polishing (CMP).

16. A chemical mechanical polishing (CMP) tool arrangement comprising: at least one CMP station for applying a rough CMP processing to a sample, and said surface planarization system of claim 1, the surface planarization system being located downstream of said at least one CMP station and being operable for applying fine surface planarization to said sample by said selective etch.

17. A method of processing samples progressing on a production line, the method comprising: applying a rough CMP processing to the sample, in at least one CMP step; applying optical metrology measurements to the sample after said rough CMP processing and generating process control data indicative of a thickness profile for a target layer on the sample; applying fine surface planarization to the measured sample, said fine surface planarization comprising: interacting the sample with an etching material composition, and applying energy to the sample during said interaction with the etching material composition thereby creating a temperature pattern in the sample determined in accordance with said measured thickness profile, said temperature pattern creating a corresponding etch map at the surface of the sample, such that different locations of the sample's surface are subjected to different material removal rates by said etching material composition.

18. The surface planarization system of claim 11, wherein said material removal system is configured for material removal by chemical mechanical polishing (CMP).

19. The processing system of claim 13, wherein said material removal system is configured for material removal by chemical mechanical polishing (CMP).

20. The processing system of claim 14, wherein said material removal system is configured for material removal by chemical mechanical polishing (CMP).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0038] FIGS. 1A and 1B schematically illustrate configuration and operation of a CMP tools arrangement used in semiconductor industry;

[0039] FIG. 2 is a schematic illustration of a surface planarization system of the present invention;

[0040] FIGS. 3A to 3D exemplify the present invention being used for selective etching of a sample, where FIG. 3A shows the sample's structure which is to undergo the partial material removal by selective etching and the main constructional parts of the material removal system applied to the sample; and FIGS. 3B to 3D show the sample in its three successive states, before selective etching, under selective etching, and after the selective etching; and

[0041] FIG. 4 schematically illustrates a modified CMP tool arrangement utilizing the surface planarization system of the present invention replacing the conventional fine CMP stages.

DETAILED DESCRIPTION OF EMBODIMENTS

[0042] As described above with reference to FIGS. 1A and 1B, the material removal process, conventionally applied to semiconductor wafers progressing on a production line, includes CMP rough removal followed by several CMP fine stages, where each CMP stage consists of polishing the entire surface of the wafer.

[0043] Reference is now made to FIG. 2 schematically illustrating a material removal/surface planarization system, generally at 100, of the present invention, applied to a sample S interacting with (coated by/embedded in) etching material composition 11. The system 100 includes an external energy source 102 and is associated with a control unit 106. As will be described further below, the control unit 106 may be part of the system 100 or an inspection/measurement station, or a part of a stand alone system interconnected (e.g. via wireless data communication) between the surface planarization system 100 and the inspection station, or the software utilities of the control unit may be distributed between any two or more of such systems/stations.

[0044] The energy source 102 is configured and operable for generating a localized energy/temperature distribution E(x,y) within a processing region 104 and is operable by the control unit 106 to create a predetermined temperature pattern within the processing region, such that different locations of the processing region 104 are subjected to different temperatures. Hence, when an interaction interface between the sample S and etcher 11 is located in the processing region 104 it is affected by a corresponding temperature pattern T(x,y) such that different temperatures at different locations of the sample's surface creates different material removal rates by the etching material composition.

[0045] The external energy source may be of any known suitable type, e.g. electric, optical (lamps, lasers, etc.), magnetic, e.g. using pulsed or CW radiation. In a non-limiting example, the energy source 102 may include a matrix of spaced-apart heaters arranged to be aligned with a corresponding matrix of locations within the sample's surface, such that actuation of the selective heaters with required working parameters (heating temperature, operational mode (e.g. pulses), duration of heating, pulse shape, time pattern of pulses) creates a heat distribution pattern across the sample.

[0046] The control unit 106 is configured for generating operating data to the energy source 102 to create the localized temperature distribution E(x,y), i.e. spatial variation of the temperature field within the processing region, such that a corresponding temperature pattern/profile T(x,y) is created at the sample's surface S (interaction interface with etcher) while located in the processing region 104. When the sample with such temperature profile therealong interacts with a suitable etching material composition, a corresponding profile of the material removal parameter(s) (e.g. variable etch rate at different locations on the sample), defined by the local sample's temperature, is created along the interaction interface, and accordingly different locations of the sample in the interaction region are differently affected by the temperature field causing different levels of material removal at different sample's locations, e.g. material removal at selected locations on the sample. Examples of the energy sources 102 that create temperature field pattern can be lamps, lasers, and other sources CW or pulsed sources.

[0047] The control unit 106 is typically an electronic/computer system including inter alia such utilities (hardware and/or software) as data input and output utilities 108 and 110, and an energy controller utility 112. The energy controller utility 112 is a data processor including a pattern data generator module 114, which processes input data indicative of sample's locations (coordinates) from which material is to be removed (a so-called wafer map or etch map) and generates data indicative of a corresponding energy distribution pattern E(x,y) to be produced by the energy source in the processing region where the sample's surface is located.

[0048] It should be understood that in some embodiments the input data indicative of sample's locations from which material is to be removed may be input to the control unit while being for example in the form of a measured layer thickness profile on the sample (a so-called wafer map). The wafer map data may be received. directly from an inspection system (on-line operational mode) or from a storage device (off-line mode). The data processor of the control unit may be preprogrammed for processing the sample map data, determining a corresponding etch map, and generating the operation data to the energy source to produce the corresponding temperature pattern. In some other embodiments, the input data includes input data etch map data (determined for example by a controller of the inspection system) which corresponds to a sample map indicative of thickness profile of a layer on the sample to be processed. In this case, the control unit analyses the etch map and generates operation data to the energy source indicative of the corresponding temperature pattern to be created. Generally speaking, the data processing algorithms for determining the sample map and corresponding etch map, transforming it into a matching temperature pattern may be implemented by software modules distributed between the control utilities of the control unit of the planarization system 100 and a control unit of an external inspection system (integrated or stand alone).

[0049] As further shown in FIG. 2 in dashed lines, the surface planarization system 100 of the invention may be associated with an in-situ metrology module/system 116 for the process control. Such system 116 applies measurements (e.g. optical) to the sample during the selective etch process performed by system 100 (i.e. by the energy source operation) and supply the updated input data (e.g. sample map or etch map, as the case may be) to the control unit for controlling the working parameters of the energy source and thus controlling the selective removal process. The metrology module 116 is configured for single- or multi-site/point measurements of the target parameters during the selective etch process. Such measured parameters include, but not limited to, a thickness of the layer that is being partially of fully removed from the sample. It should also be noted that such metrology module 116 for real time in-situ material removal (selective wet etch) can monitor composition/concentration of the etch solution instead or in addition to the sample's parameters measurements.

[0050] As indicated above, the selective material removal technique of the present invention (i.e. different levels of material removal at different locations on the sample's surface) can be used with any material removal process which has temperature dependence. In some embodiments, such different levels of material removal at different locations on the sample's surface may be constituted by variable etch rate of a material on the sample defined by the varying local sample temperatures. This may for example be achieved through selective wet etch process. Also, as mentioned above, removal of the target material to be achieved by the present invention refers to partial removal of the material up to the target thickness, as well as complete removal of the target material(s).

[0051] It should also be understood that the etching mode itself (temperature/duration, etching material compositions) may utilize any suitable technique, which are generally known in the art of etching processes commonly used in lithography, e.g. as used in semiconductor industry. Examples of selective etch agents and temperature dependence of selective etch micromachining processes are known in the art, e.g. described in the article K. R Williams and R. S Muller, Etch Rates for micromachining processing, Journal of Microelectromechanical Systems, Vol, No4, p 256-269, December 1996.

[0052] Reference is made to FIGS. 3A to 3D which exemplify how the present invention is used for selective etching of a sample. FIG. 3A exemplifies the sample's structure S which is to undergo the partial material removal by selective wet etch process of a target material, and the surface planarization system 100 applied to the sample. As shown, the sample's structure S includes a substrate (single- or multi-layer) 15 and a top layer 17 of target material, which is to be partially removed from selective locations, e.g. layer 17 is to be patterned, which patterning may be aimed at final surface planarization. To this end, an etching solution 11 is applied to the sample, e.g. is deposited onto top layer 17, via an etch reagents delivery system (nozzle), generally at 120.

[0053] The construction and operation of such material delivery systems are known per se and do not form part of the invention, and therefore need not be specifically described, except to note that any material delivery system can be used, including material delivery system with a rotation mechanism for creating a paddle. The system 100 includes an external heating source 102 (constituting energy source) capable of creating localized energy distribution E(x,y) in a processing region 104, where the sample interacting with etching material is located, and operable by a control unit 106 such that the localized energy field distribution creates desired temperature profile T(x,y) within the sample-etch interface. As illustrated in the figure, the heating source 102 may include a heating unit accommodated at the sample's surface side being spaced and configured for directing heating radiation towards the sample's surface, and/or may include a heating unit accommodated inside a sample's holding chuck 122. The heating unit(s) is/are operable by data from the pattern data generator of the control unit to allow localized heating of any part of the sample's surface. As indicated above, the localized heating can be done by any pulsed or CW sources. The system 100 may be associated with a metrology module (inspection system) for real time in-situ control of the material removal process.

[0054] FIGS. 3B to 3D exemplify the operation of the system 100. Three successive states of the sample are shown, before the selective etching by system 100, under the selective etching, and after the selective etching. As shown in FIG. 3B, sample S progressing on the production line, e.g. resulting from a preceding rough CMP stage, includes a substrate 15 and a target material 17 on the substrate. The target material 17 has a pattern, i.e. a surface relief, exemplified here as three regions R.sub.1, R.sub.2 and R.sub.3 of in different thicknesses. This sample undergoes surface planarization processing of the technique of the invention (FIG. 3C): etching material/layer 11 is added above the target layer 17, and the entire structure is subjected to a temperature pattern created by external energy source 102. As described above, the energy source 102 is operated by the control unit 106, which utilizes input data (etching material used, required final thickness profile, as well as parameters of the heating source, and determines the working parameters of the surface planarization system (e.g. heating temperature map/pattern (providing desired etch map), optimal usage of pulsed or CW operational mode, duration of heating, heating pulse shape, time pattern of heating pulses) to ensure creation of desired heat (temperature) distribution within the interface and duration of the heat application to achieve the desired etch rate pattern/profile. As shown in FIG. 3C, such selected energy distribution results in the desired pattern of material removal, i.e. the sample S has a desired thickness pattern of the target material layer 17, achieved in a single-stage process.

[0055] As indicated above, the technique of the present invention may be used for the fine tuning and/or correcting and/or improving of a CMP tool performance, at various possible configurations. For example, the surface planarization system 100 of the invention can be integrated or used as part of an existing CMP process equipment as an additional module located in the CMP sequence after the platen or platens, or instead of one of the platens, or instead of the last or buffing platen. This is shown schematically in FIG. 4. Here, the surface planarization system 100 is used as a part of the CMP tool arrangement 200, and is installed downstream of the metrology/inspection station 18 (integrated metrology tool), which receives and inspects a sample after being processed by the rough CMP stage 12. In this example, the control unit receives input data from the inspection system 220 and delivers output data for operation of the surface planarization system 100. Also, as indicated above, the surface planarization system of the invention can be used as a Stand-Alone (SA) tool, as a so-called verification station, for correction after the standard CMP process (e.g. conventional multi-stage material removal process of FIGS. 1A and 1B) was completed.

[0056] It should be noted that the integrated technique for the fine tuning and/or correcting and/or improving of the CMP tool performance allows better productivity, cost effectiveness and better throughput of CMP tool arrangement, by elimination or at least significant reduction of the rework, over polish step or steps, reduction of number of platens and reduction of selectivity requirements of different CMP slurries. Also, such fine tuning and/or correcting and/or improving of the CMP process allows better overall performance, including improvement of Within Wafer (WIW) thickness uniformity of CMP process, reduction or elimination of such detrimental CMP effects as erosion and dishing, reduction or elimination of the density effects, as well as reduction of CMP induced defects, such as scratches, and simplify the cleaning processes required after CMP. It should also be noted that all stop-on CMP steps (including but not limited to Oxide CMP with stop on SiN, and SiN CMP with stop on Oxide, or Oxide CMP with stop on Poly-Si, W CMP with stop on Oxide, etc.) that currently require multi-platen processing with problematic over polish step and/or buffing, can be reduced with addition of the technique of the invention to a more simple single-platen stop-in layer bulk material removal methods and tools.

[0057] The invention is applicable for selective removal or etching of oxide, SiN, Si, metals, etc. using known selective etch agents and known temperature dependence. The invention can be used to correct CMP performance for both dielectric and metal CMP processes, including but not limited to STI CMP, replacement gate CMP, W CMP, Cu CMP, etc. It should further be noted that the technique of the invention, exemplified above as being used with CMP process, can also be used for other semiconductor manufacturing processes, such as patterning process, or material deposition process, e.g. Chemical Vapor Deposition (CVD), for controlling/verifying/correcting the final material thickness profile.

[0058] The following is an example of the advanced process control scheme suitable when using the surface planarization system 100 of the invention as an integrated part of the existing CMP process equipment, e.g. as illustrated in and described above with reference to FIG. 4. According to this process control scheme, the Wet Area Integrated metrology (IM) tool/station 220 is located downstream of the platen or platens 14 of the CMP (e.g. rough CMP) and upstream of the system 100. The wafer is kept dry or wet while being examined by IM tool 220. This wet area IM system 220 is configured for measuring/determining the wafer map of the target parameters after the rough CMP by platen 14 and defining the required material removal needs, i.e. the final thickness pattern or the pattern of the thickness change, as the case may be. This wafer map (e.g. data indicative of sample's locations from which material is to be removed) is used as Feed Forward advanced process control for the proposed integrated selective etch removal system 100 (i.e. determination of the corresponding etch map), and the same wafer map is used as Feed Back advanced process control to the CMP platen 12. In addition, as an option, additional metrology tool 20 (integrated or stand alone) can be used after completion of the entire material removal and surface planarization processes, i.e. downstream of system 100, serving mean of overall process quality control.

[0059] In case the surface planarization system 100 is used in a separate stand alone station/tool configuration for correction after standard CMP process is completed, a stand-alone metrology system can be used to pre-define the wafer map of the required removal/planarization needs (i.e. required thickness profile), prior to application of the selective wet etch process (Feed-Forward advanced process control), and to assess the overall performance after the selective wet etch process (Feed-Back advanced process control).

[0060] As described above with reference to FIG. 2, and also exemplified in FIG. 4, in-process control can be optionally used to control the selective removal process. In this case additional in-situ metrology module 116 can be used for input to the control module 100. This metrology module 116 allows measurement (single or multiple points/areas) of the target parameters during the etch process including, but not limited to, thickness of layer that is being partially of fully removed. As described above, the metrology module 116 for real time in-situ material removal (selective wet etch) can monitor composition/concentration of the etch solution instead or in addition to the sample measurements.

[0061] For example, the STI CMP process using the present invention, can be done as follows: A wafer is made planar with high efficiency oxide slurry, such that a thin uniform layer of Oxide remains on the wafer being polished and a thin Oxide layer still remains. The thickness of the remaining oxide layer across the wafer is measured to define the required temperature distribution and heat duration pattern for the removal process. Selective removal (etch) according to the invention is performed to entirely remove the remaining oxide layer, and SiN is exposed uniformly across the wafer without dishing/erosion, excessive over polish, etc. To this end, the STI CMP tool can for example be modified as follows: one of the polishing platen is used for planarization with high planarization efficiency oxide slurry; the IM (dry/wet) wet area metrology module 220 is located downstream of the polishing stage to measure the residue wafer map, and the surface planarization system 100 of the invention is then applied for selective removal of the residue layer. Then, after the wafer is cleaned and dried it is measured by Dry metrology tool 20 (integrated or stand alone) for overall quality of the process.