Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P74/00—Testing or measuring during manufacture or treatment of wafers, substrates or devices
  • H10P74/20—Testing or measuring during manufacture or treatment of wafers, substrates or devices characterised by the properties tested or measured, e.g. structural or electrical properties
  • H10P74/203—Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/55—Specular reflectivity
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F30/00—Computer-aided design [CAD]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0402—Apparatus for fluid treatment
  • H10P72/0406—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like
  • H10P72/0411—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing
  • H10P72/0412—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing using mainly scrubbing means, e.g. brushes
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0402—Apparatus for fluid treatment
  • H10P72/0406—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like
  • H10P72/0411—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing
  • H10P72/0414—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing using mainly spraying means, e.g. nozzles
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/04—Apparatus for manufacture or treatment
  • H10P72/0402—Apparatus for fluid treatment
  • H10P72/0418—Apparatus for fluid treatment for etching
  • H10P72/0422—Apparatus for fluid treatment for etching for wet etching
  • H10P72/0424—Apparatus for fluid treatment for etching for wet etching using mainly spraying means, e.g. nozzles
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/06—Apparatus for monitoring, sorting, marking, testing or measuring
  • H10P72/0604—Process monitoring, e.g. flow or thickness monitoring
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P74/00—Testing or measuring during manufacture or treatment of wafers, substrates or devices
  • H10P74/23—Testing or measuring during manufacture or treatment of wafers, substrates or devices characterised by multiple measurements, corrections, marking or sorting processes
  • H10P74/238—Testing or measuring during manufacture or treatment of wafers, substrates or devices characterised by multiple measurements, corrections, marking or sorting processes comprising acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection or in-situ thickness measurement

Definitions

• the conventional process for thinning non TSV wafers involves grinding to remove the bulk of the wafer and a multistep sequence of processes that includes chemical mechanical planarization (CMP) and plasma etching to complete the final thinning of the wafer.
• CMP chemical mechanical planarization
• this conventional process has a number of disadvantages associated therewith including but not limited to the complexity of the process and the associated costs.
• the present invention is directed at overcoming these deficiencies associated with the conventional process by providing a simple, cost effective method to wet etch the remaining substrate to a desired thickness and surface uniformity.
• a system for performing a wet etching process is provided.
• the system includes a housing and a number of wafer/substrate processing stations disposed therein, including a measurement station which includes among other things an imaging device configured to measure an initial thickness information and a final thickness information for a substrate in real time. Also within the housing is an etching station that includes a single wafer wet etching device. An automated substrate transfer device is configured to controllably move the substrate between the measurement station and the single wafer wet etching station and any other stations included in the system.
• a computer implemented control system is communicatively coupled to the processing system and the stations therein. The control system is configured to control the wet etching process by causing the imaging device to measure the thickness of the substrate, and using that thickness information calculate an etch recipe for the substrate in real time.
• the controller also is configured to cause the single wafer wet etching device to etch the substrate according to the etch recipe, and, after the substrate is etched, cause the imaging device to re-measure the final thickness information.
• the control system can calculate, in real time, the etch recipe as a function of the final thickness information from a previous substrate.
• the etching station can include an end-point detection device that can include a high intensity light emitter and detector and the control system can be configured to detect a reveal point for a substrate having TSVs using the information collected by the end- point detection device during the etching process.
• the system can also include one or more cleaning stations within the housing and communicatively coupled to the control system to clean a substrate after the etching process.
• a method for wet etching a substrate using a single wafer wet etching processing system includes measuring, at a
• the method also includes calculating an etch profile for the particular substrate according to the initial thickness information and according to the desired final etch profile which is the target physical characteristics of the substrate after processing. Calculating the etch profile can include calculating the radial thickness of the substrate and an etch depth.
• an etch recipe is generated for the particular substrate according to the calculated etch profile. The etch recipe includes settings for various parameters that control the execution of the wet etching process.
• the method also includes etching the particular substrate according to the etch recipe in order to achieve the desired final etch profile.
• the various stations used to perform this exemplary process are disposed within a housing of the processing system and are accessed by an automated substrate transfer device that is configured to controllably move the substrate between stations, thereby allowing
• the method can also include the step of measuring final thickness information at the measurement station for the particular substrate after it has been etched.
• the final thickness information can be used to calculate the etch recipe for subsequently processed substrates.
• the method can also include one or more steps for cleaning the particular substrate in a cleaning station disposed within the processing system.
• the method, in particular the etching step can also include the step of detecting the point in which one or more TSVs with a substrate are revealed using an end point detection device included within the etching station.
• a method for detecting an end point of an etching process in which a particular substrate having TSVs is being etched using a single wafer wet etching processing system includes emitting light onto at least a sample area of a surface of the particular substrate and detecting a reflection of the light off of the sample area of the surface.
• the method also includes calculating an intensity of the reflection and comparing the intensity to a reference intensity.
• the reference intensity is indicative of a reveal point, which is a point during the etching process at which the TSVs are revealed on the surface of the particular substrate (i.e., the etchant has removed the substrate layer above the TSVs to the point where the TSVs are exposed).
• a computer implemented control system for determining an end-point of a wet etching process of a substrate having TSVs by a single wafer wet etching station.
• the single wafer wet etching station including a single wafer wet etching device, a light emitter and a light detector, and the control system including one or more processors communicatively coupled to the single wafer wet etching device, the light emitter and the light detector and configured to interact with a computer-readable storage medium and execute one or more software modules stored on the storage medium.
• the software modules include an end-point detection module configured to cause the light emitter to emit a light onto at least a sample area of a surface of the substrate and cause the light detector to detect a reflection of the light off of the sample area of the surface.
• the endpoint detection module is also configured to calculate an intensity of the reflection and compare the intensity of the reflection to a reference intensity, wherein the reference intensity is indicative of a reveal point which is the point during the etching process at which the TSVs are revealed on the surface of the substrate.
• the control system can determine when the intensity corresponds to the reference intensity and set an end point of the etching process in view of the identified reveal point and optionally in view an over etch duration as defined by a user.
• Fig. 2 is a front plan view showing a system for performing a wet etching process in accordance with one embodiment disclosed herein;
• Fig. 5 is a perspective view showing a wet etching station in accordance with one embodiment disclosed herein;
• Fig. 6A is a front plan view showing a cleaning station in accordance with one embodiment disclosed herein;
• Fig. 9A is a cross-section view showing an exemplary silicon substrate having TSVs in accordance with one embodiment disclosed herein;
• Fig. 9B is a graph showing the radial thickness of an exemplary substrate in i
• Fig. 9D is a graph showing an exemplary relationship between spin-speed, etch rate and etchant temperature in accordance with one embodiment disclosed herein;
• Fig. 9E is a graph showing an exemplary relationship between etch rate and etchant concentration in accordance with one embodiment disclosed herein
• Fig. 9F is a graph showing an exemplary relationship between arm scan speed and dwell time as a function of radial position in accordance with one embodiment disclosed herein;
• Fig. 9H illustrates an exemplary scanning electron microscope image of a substrate having TSVs in accordance with one embodiment disclosed herein;
• Fig. 91 illustrates an exemplary scanning electron microscope image of a substrate having TSVs in accordance with one embodiment disclosed herein;
• Fig. 10 is a flow diagram illustrating a routine for performing a wet etching process in accordance with at least one embodiment disclosed herein;
• Figs, 1-5 illustrate a system 100 for performing a wet etching process in accordance with one embodiment of the present invention.
• the system 100 can thus be thought of as being a wet-etching facility for manufacturing semiconductor devices.
• a single wafer wet treatment apparatus used in an etching process dispenses chemical etchant in a controlled manner on a substrate for inducing a chemical reaction during a fixed time. It will be understood that the terms "wafer” and “substrate” are used interchangeably herein.
• a single wafer wet treatment apparatus used in a cleaning process causes a chemical solution to be dispensed onto a substrate and can also include a scrubbing device to mechanically scrub the substrate.
• Each of the wet treatment apparatuses can include a bath that collects fluids that overflow and discharge to an outer tank (or bath) or recirculate.
• the single wafer wet treatment apparatuses are further composed of conduits (e.g., pipes) which supply or discharge fluids (e.g, chemicals, water, solutions and the like) in the bath, and various kinds of control means for controlling fluid temperature or concentration and other process parameters as further described herein.
• the wafer wet treatment process can also include a measuring step whereby the wafers are measured for thickness.
• conventional systems for performing wet etching there are a number of pieces of equipment that are used; however, there is generally a lack of integration between the pieces of equipment.
• the system 100 of the present invention is for the most part a largely or fully integrated system, thereby greatly reducing or eliminating unnecessary wait or down times, etc. between processing steps.
• the system 100 is an integrated system that is defined by a number of different devices (equipment pieces) that are located at different stations within a housing 1 10.
• the housing 1 10 is generally in the form of an upstanding cabinet or the like that has a plurality of walls 1 12 that define a hollow interior 120.
• the hollow interior 120 can be accessible through a number of different access points, including but not limited to a door assembly 130 shown at one end of the housing 1 10 and one or more side walls 1 12 can include windows 140 to allow direct access and viewing of the hollow interior 120 and more particularly, the equipment and processing stations included therein.
• one side wall 1 12 can include transparent windows 140 and one or more access points 150.
• the opposite side walls 112 can include an access point 150 of a different form, such as a set of doors as shown in Fig. 2.
• Each access point 150 can be in the form of an opening that provides an entrance into the hollow interior 120 and in addition, a wafer holding and loading device (loadport) 160 can be provided at such location along one side wall 1 12.
• the device 160 can be any number of conventional devices that are designed to hold and permit access to wafers contained therein and can be in the form of a FOUP loadport, with FOUP being an acronym for Front Opening Unified Pod or Front Opening Universal Pod.
• a FOUP is a specialized plastic enclosure with a cassette therein designed to hold silicon wafers securely and safely in a controlled environment, and to allow the wafers to be removed for processing or measurement by tools equipped with appropriate ioadports and robotic handling systems.
• the device 160 can be in the form of an input/output cassette device.
• the wafer holding and loading device (loadport) 160 can be in the form of an input/output wafer cassette device which includes a housing which is configured to receive and hold a cassette holding a plurality of wafers.
• the housing can include a door 162 at each end thereof, with one door 162 facing outwardly away from the hollow interior 120 so as to allow a technician to load one or more wafers, into the loadport 160.
• Another door 162 faces and is accessible within the hollow interior 120 so as to permit automated removal (and reloading) of the wafer from within the hollow interior 120 to allow the wafer to be transferred to the various stations contained within the hollow interior 120.
• the wafer holding and loading device 160 can be of the type that includes a plurality of racks or the like for holding a plurality of wafers in a vertically stacked manner.
• the housing (cabinet) 1 10 can also include one or more computer terminals 170 which operate in the manner described below and allow the technician to both control and monitor the processing of the wafer within the housing 1 10 as the wafer is subjected to the various processing steps at the different stations,
• a wafer transfer device 300 is provided and is configured to move one or more wafers from between the various stations of the system 100.
• the wafer transfer device 300 can take any number of different forms but generally is in the form of an automated device, such as a robot, that is configured to controllably grasp, move and release one or more wafers.
• the wafer transfer device 300 includes a robotic arm that has a grasp (holding) mechanism for grasping and holding a wafer and has a base about which the robotic arm can move in multiple directions (multiple degrees of freedom). It should be understood that one or more of the process stations/chambers can be combined to have multiple process functions.
• the measuring apparatuses used in the measuring chamber can be incorporated into the wet etch chamber to provide a combined measuring and etch station.
• the etch chamber and cleaning chamber can be combined into multi-process chambers as would be understood by those skilled in the art.
• the wafer transfer device 300 can thus be thought of as being an automated wafer handler. It will also be appreciated that the wafer transfer device is a computer operated device and therefore, as described below, operates in accordance with the execution of a software application, etc. In addition, it will also be appreciated that the wafer transfer device 300 can be operated in response to user generated commands, such as commands that are generated by the technician at a user interface, such as the computer terminal 170.
• the wafer transfer device 300 is shown as being centrally located within the interior of system 100, it is not limited to assuming such a position within the system so long as the wafer transfer device 300 is located at a position that allows the device 300 to access each of the stations of the system and transfer the wafer between all of the necessary stations.
• the first station 200 includes one more wafer holding and loading devices (FOUP loadport or input/output cassettes) 160 for holding wafers in a sealed and secure manner.
• FOUP loadport any number of different conventional wafer holding and loading devices (FOUP loadport) 160 can be used in system 100.
• the wafer holding and loading device (FOUP loadport) 160 is of a type that contains a cassette holding the wafers.
• the door 162 is positioned such that the wafer transfer device (robot) 300 can directly access the wafers from the FOUP.
• the wafer holding and loading device (FOUP loadport) 160 can also include recognition features, such as RFID tag, barcode reader, etc. to allow it to be identified by readers on tools, etc.
• loadport 160 is not limited to being of an FOUP type.
• Various wafer holding and loading mechanisms can be used in addition to FOUPs having built in cassettes such as wafer boxes having removable cassettes as would be understood by those skilled in the art.
• Fig. 3 shows two blocks as constituting the station 200, it will be understood that this is only for illustrative purposes and is not limiting of the present invention since, as shown in Fig, 1 , system 100 can include more than one wafer holding and loading device (FOUP loadport) 160.
• each loadport 160 can be configured to receive one or more cassettes.
• the imaging device 600 also includes a non-contact measurement component 620 that measures at least the thickness of the wafer and is also configured to detect (measure) and generate a surface profile for the wafer.
• the non-contact measurement component 620 includes imaging equipment and can be part of an automated device to allow movement of the component 620 with respect to the wafer on the platform 610.
• the non- contact measurement component 620 can be in the form of an arm or the like that can move in any number of different directions (x, y, z) with respect to the wafer (i.e., the component 620 has multiple degrees of freedom of movement).
• the imaging device 600 is described in greater detail hereinafter.
• the measuring station 210 is directly incorporated into and contained within the housing (cabinet) 1 10.
• the second station 210 and the imaging device 600 contained thereat is within reach of the wafer transfer device (robot) 300.
• This positioning allows the automated wafer transfer device 300 to easily move a wafer between the second station 210 and any of the other stations of the system 100.
• This is in direct contrast to conventional system in which measuring equipment is located at a remote location and requires wafers to be removed from the etch process in order for a measurement to be taken.
• the wet etching apparatus 400 located at the third station 220 also includes spin chuck 420 (variable speed controlled by an etch controller 401 which is part of the overall process control system described herein) on which the wafer rests, as well as an etch tool (arm) 430 that includes one or more nozzles (orifice) 435 that dispenses a fluid (e.g., one or more liquids, preferably the chemical etchant).
• the etch tool 430 can be in the form of an arm that is movable along multiple directions (x, y, z directions) and thus, has multiple degrees of freedom.
• the etch tool 430 is a controllable tool in that it is controlled by a computing device such as etch controller 401 and is part of the overall programmable computer system employed in the system 100 as described herein. As a result, the etch tool 430 can be driven to any specific location of the wafer, etc.
• the wet etching apparatus 400 also includes a fluid delivery and fluid removal system for both introducing the etch chemicals and removing such chemicals from the chamber. These components are implemented using a conventional fluid plumbing scheme in which conduits are provided for supplying fluid (e.g., one or more liquids, preferably a chemical etchant) to the nozzle 435.
• the wet etching apparatus 400 includes conduits and mechanisms for discharging fluid(s) that accumulate within the enclosure 410 during the wet etching process.
• the mechanical chuck 420 permits the chuck 420 to hold the wafer.
• the chuck 420 includes a main shaft (not shown) which can be joined to a driving shaft of a motor so as to allow the wafer held by the spin chuck 420 to make a spin rotation about a Z-axis.
• a power source switch of the motor is connected to an output side of the etch controller 401 , with the result that the rotation speed of the motor is controlled by the controller 401.
• the spin chuck 420 can be supported by a lift mechanism (not shown) so as to be movable in a direction of the Z-axis.
• any number of suitable etching solutions can be used so long as they are suitable for a wet etching process and for the intended substrate and application.
• different chemistries can be used based on a number of different parameters, including in view of the properties of the wafer.
• the wet etching apparatus 400 also includes means for controlling the flow properties (flow rate) and temperature of the etchant solution.
• the operating system can include one or more first flow rate control sections, including but not limited to a pump or valve, that extend from a liquid supply source to a nozzle.
• the operating section of the flow rate control section can be connected to the output side of the etch controller 401 so as to control the flow rate of the etchant solution supplied to the nozzle.
• other control mechanism can be used to control the concentration of the etchant solution.
• the control of the concentration of the etchant is one means for controlling the overall etch rate and etch process for a given wafer.
• the device 500 is responsive to a computing device, such as etch controller 401 or computing device 170, and the light emitting device 510 emits light (e.g., white light) onto at least a portion of the surface of the particular wafer in the wet etching station 220.
• the light detector 520 e.g., CCD detector
• the end point detection device 500 is advantageously employed by the present invention to expose via materials to a precise and uniform depth. It will be appreciated that the device 500 is not limited to being formed of the above pieces of equipment but in generally is an optics based system in which light characteristics are analyzed in order to determine a property or condition of the substrate.
• the cleaning station 230 can be of a wafer cleaning apparatus 1600 (of the scrubbing or brush box type) in which the wafer is scrubbed while a cleaning solution is dispensed on the wafer to remove larger residual particles and etch residue.
• the wafer cleaning apparatus 1600 can include a chamber (enclosure) 1610 that contains the equipment and contains the injected cleaning solution used in the cleaning process.
• the chamber thus at least partially is a sealed environment and can include a wafer scrubbing device 1615 which comprises a chuck 1620 (e.g., spin, rotating chuck) for supporting a wafer to be cleaned.
• the wafer scrubbing device also comprises a brush mechanism which includes one or more brushes 1630 for scrubbing the wafer.
• the final cleaning apparatus 1700 can be in the form of a chamber 1710 and includes one or more arms 1740 and nozzles 1750 to dispense a high velocity spray onto the wafer and/or use a megasonic cleaning apparatus 1780 for the removal of small particles from the wafer surface.
• station 240 can include a drying apparatus 1790 to dry the wafer at the end of the final cleaning process.
• Process controller 705 can be configured to communicate with the various computer- controlled components of the system 100, including first station 200, second station 210, third station 220, fourth station 230, fifth station 240, and the computer controlled devices or controllers associated therewith including but not limited to wafer transfer device 300, FOUP loadports 160, imaging device 600, etch controller 401, end point detection device 500 and cleaning controller 1601 transmitting electronic information to and receiving electronic information from the various components.
• FIG. 7A depicts the process control system 700 with respect to a process controller 705, it should be understood that any number of process controllers can interact with the process control system 700 and the constituent computer controlled components of system 100 in the manner described herein.
• the various computing devices and machines referenced herein including but not limited to computer terminal 170, process controller 705, first station 200, second station 210, third station 220, fourth station 230, fifth station 240, and the computer controlled devices or controllers associated therewith including but not limited to wafer transfer device 300, FOUP loadports 160, imaging device 600, etch controller 401, end point detection device 500 and cleaning controller 1601 are referred to herein as individual/single devices and/or machines, in certain implementations the referenced devices and machines, and their associated and/or accompanying operations, features, and/or functionalities can be arranged or otherwise employed across any number of devices and/or machines, such as over a direct connection or network connection, as is known to those of skill in the art.
• Fig. 7B is a block diagram illustrating an exemplary configuration of process controller 705 of the system 100 for performing a wet etching process.
• Process controller includes various hardware and software components that serve to enable operation of the system, including a processor 710, memory 720, display 740, storage 790 and a communication interface 750.
• Processor 710 serves to execute software instructions that can be loaded into memory 720.
• Processor 710 can be a number of processors, a multi-processor core, or some other type of processor, depending on the particular implementation.
• memory 720 and/or storage 790 are accessible by processor 710, thereby enabling processor to receive and execute instructions stored on memory and/or on storage.
• Memory can be, for example, a random access memory (RAM) or any other suitable volatile or non-volatile computer readable storage medium.
• RAM random access memory
• memory can be fixed or removable.
• Storage 790 can take various forms, depending on the particular implementation. For example, storage can contain one or more components or devices such as a hard drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, or some combination of the above. Storage also can be fixed or removable.
• One or more software modules 730 are encoded in storage 790 and/or in memory 720.
• the software modules can comprise one or more software programs or applications having computer program code or a set of instructions executed in processor 710.
• the program code can execute entirely on process controller 705, as a stand-alone software package, partly on process controller, or entirely on another computing/device or partly on another remote computing/device.
• an imaging module 770 included among the software modules 730 is an imaging module 770, an end point detection module 772, an etch recipe module 774, a clean control module 776, and a database module 778 and display module 780 that are executed by processor 710.
• the processor configures the process controller 705 to perform various operations relating to the system 100 for performing a wet etching process, as will be described in greater detail below.
• program code of software modules 730 and one or more computer readable storage devices form a computer program product that can be manufactured and/or distributed in accordance with the present invention, as is known to those of ordinary skill in the art.
• one or more of software modules 730 can be downloaded over a network to storage 790 from another device or system via communication interface 750 for use within the system 100.
• software modules 730 can be downloaded over a network to storage 790 from another device or system via communication interface 750 for use within the system 100.
• other information and/or data relevant to the operation of the present systems and methods can also be stored on storage, as will be discussed in greater detail below.
• database 785 contains and/or maintains various data items and elements that are utilized throughout the various operations of the system 100.
• the information stored in database can include but is not limited to, parameter adjustment algorithms, recipes, chemical mixture details, set-points, settings, alarms, actual values for process variables, and historical data collected and analyzed by the process controller (e.g, batch records, substrate thickness measurement information, via depth measurement information) as will be described in greater detail herein.
• database is depicted as being configured locally to process controller 705, in certain implementations database and/or various of the data elements stored therein can be located remotely (such as on a remote computing device or server - not shown) and connected to process controller through a network or in a manner known to those of ordinary skill in the art.
• An interface 715 is also operativeiy connected to the processor 710, The interface can be one or more input device(s) such as switch(es), button(s), key(s), a touch-screen, microphone, etc. as would be understood in the art of electronic computing devices. Interface serves to facilitate the capture of commands from the user such as on-off commands or settings related to operation of the system 100.
• Display 740 is also operativeiy connected to processor 710.
• Display includes a screen or any other such presentation device which enables the user to view information relating to operation of the system 100 including control settings, command prompts and data collected by various components of the system 100 and provided to process controller.
• display can be a digital display such as a dot matrix display or other 2-dimensional display.
• interface and display can be integrated into a touch screen display.
• the screen is used to show a graphical user interface, which can display various data and provide "forms" that include fields that allow for the entry of information by the user.
• Touching the touch screen at locations corresponding to the display of a graphical user interface allows the person to interact with the device to enter data, change settings, control functions, etc. So, when the touch screen is touched, interface communicates this change to processor, and settings can be changed or user entered information can be captured and stored in the memory.
• Communication interface 750 is also operativeiy connected to the processor 710 and can be any interface that enables communication between the process controller 705 and external devices, machines and/or elements including [robot, imaging device, etch controller, clean controller, chemistry controller].
• communication interface includes, but is not limited to, Ethernet, IEEE 1394, parallel, PS/2, Serial, USB, VGA, DVI, SCSI, HDMI, a Network Interface Card (NIC), an integrated network interface, a radio frequency transmitter/receiver (e.g., Bluetooth, cellular, NFC), a satellite communication transmitter/receiver, an infrared port, and/or any other such interfaces for connecting process controller 705 to other computing devices and/or communication networks such as private networks and the Internet.
• NIC Network Interface Card
• radio frequency transmitter/receiver e.g., Bluetooth, cellular, NFC
• satellite communication transmitter/receiver e.g., an infrared port
• Such connections can include a wired connection (e.g. using the
• process controller 705 can communicate with one or more computing devices, for instance, computing devices used to operate the various process stations and constituent devices as will be further described in greater detail herein.
• computing devices can transmit and/or receive data to/from process controller 705 and between one another, thereby preferably initiating maintaining, and/or enhancing the operation of the system 100, as will be described in greater detail below.
• Fig. 8 is a flowchart illustrating a process flow 800 for etching wafers using system 100 in accordance with an embodiment of the invention.
• the exemplary process can be performed on post grind TSV substrates (i.e., wafers) in which the TSVs are not exposed on the top surface of the substrate due to a layer of overburden.
• the bottom surface of the substrate is mounted to a carrier with an adhesive layer that can vary in thickness from one substrate to another.
• substrates are not limited to this particular carrier configuration as the exemplary process is operable on substrates in alternative carrier configurations and non-carrier configurations as would be understood by those skilled in the art.
• the exemplary process provides specialized metrology to determine the thickness of the overburden and wet etch substrates using the system 100 to expose the TSVs to a desired depth and substrate surface uniformity.
• process flow is generally discussed in relation to TSV substrates, it should be understood that the exemplary process can be performed on non-TSV substrates and provides specialized metrology to determine the thickness of the substrate and wet etch non-TSV substrates using system 100 to a desired thickness and substrate surface uniformity.
• the system 100 measures the thickness of a particular substrate.
• the system calculates the etch depth and radial thickness for the particular substrate in accordance with the thickness measurements taken in process block 810.
• the system generates an etch recipe for the particular substrate to achieve the desired etch profile for the particular substrate.
• the system etches the particular substrate according to the etch recipe. The step of etching the particular substrate in process block 840 can further incorporate an end point detection process as further described herein.
• the system cleans the substrate to remove any residual particles, ions and etchant.
• the system measures the thickness of the particular substrate and provides the thickness measurements to the process controller to analyze the physical properties of the substrate, evaluate the efficacy of the etch recipe, and adjust the etch recipe for subsequent substrates being put through process flow 800 accordingly.
• the grinding process leaves a layer of overburden 920 (e.g., substrate material above the TSVs) that could vary in thickness (i.e., thicker at the edge, uniform across the substrate or thicker at the center of the substrate than at the edge) (within substrate thickness variation).
• a layer of overburden 920 e.g., substrate material above the TSVs
• the adhesive layer can also vary in thickness and uniformity, rendering exterior measurements ineffective at determining the thickness and uniformity of the material remaining in the top silicon substrate, above the end of the via.
• Fig. 9A also depicts a cross section of an exemplary post etching TSV substrate.
• the sample size (number of data-points collected over the substrate surface) can be adjusted depending on the level of detail required by the application of the processed substrate, and can range from a detailed scan of the entire surface to just a few data points over the surface. More specifically, thickness measurements can be collected at various locations on a substrate, and the measurements can be used to interpolate the thickness at intermediate locations as a function of the distance between the two data points. In other words, the software of the present invention can perform an interpolation operation for generating such measurements.
• Processor 710 executing one or more software modules 730 including, preferably imaging module 770 or database module 778, can also configure the process controller 705 to record the thickness information to storage 790 or memory 720 for further processing as further described herein.
• software modules 730 including, preferably imaging module 770 or database module 778, can also configure the process controller 705 to record the thickness information to storage 790 or memory 720 for further processing as further described herein.
• processor 710 executing one or more of software modules 730, including, preferably substrate thickness module 770, configures process controller 705 to determine the radial thickness of the particular substrate and etch depth to identify the radially defined areas of the surface of the particular substrate where the substrate is thicker or thinner (e.g., edge heavy, uniform or center heavy) and the amount of material to be removed at a given radius.
• software modules 730 including, preferably substrate thickness module 770, configures process controller 705 to determine the radial thickness of the particular substrate and etch depth to identify the radially defined areas of the surface of the particular substrate where the substrate is thicker or thinner (e.g., edge heavy, uniform or center heavy) and the amount of material to be removed at a given radius.
• Radial thickness is the average thickness of the substrate at a given radius.
• surface uniformity of the particular substrate is a measure of how radial thickness varies across the surface of the wafer. Radial thickness is used to identify radial dependent non- uniformities in thickness i.e., at what radial areas on the surface of the substrate the overburden must be removed more than others. Radial thickness can be calculated according to an algorithm that is a function of the average thickness of the particular substrate measured at step 810 around a given radius of the substrate.
• Fig. 9B shows a screen shot of a graphical representation or ring map, of the radial thickness of an exemplary substrate that can be generated by the process controller and displayed by display 740.
• Etch depth is the desired depth of material to be removed from the surface of the substrate. The method of determining etch depth can vary depending on the type of substrate and intended application of the substrate.
• etch depth is the thickness of the overburden between the top surface of the substrate and the top of the TSVs.
• etch depth can also be a function of the desired height of the revealed TSVs (TSV reveal height).
• TSV reveal height the desired height of the revealed TSVs
• etch depth is determined for a sample of radial locations on the surface of the particular substrate according to an algorithm that subtracts a reference height of the TSVs and desired TSV reveal height from the radial thickness. Accordingly, etch depth is a function of radius and can be adjusted to minimize radial dependent non-uniformities in overburden thickness.
• the reference height of the TSVs in the particular substrate can be obtained from the manufacturer of the particular substrate. Alternatively, or in addition, the reference height can also be a function of measurements of the actual height of the TSVs of one or more etched substrates.
• etch depth can be calculated as a function of radial thickness and other thickness related information, including TTV (total thickness variation). Accordingly, etch depth can be adjusted to improve the overall thickness uniformity, surface uniformity of the non-TSV substrates being etched.
• processor 710 executing one or more software modules 730, including preferably etch recipe module 778, can configure process controller 705 to generate an etch recipe for the particular substrate that can be executed by the etching apparatus 400 to etch the particular substrate to obtain the desired etch profile.
• etch profile includes etch depth as determined in step 820.
• Etch profile can also include other changes that need to be made to the particular substrate to achieve the desired physical characteristics including but not limited to surface roughness.
• etch profile is a function of application dependent physical characteristics of the processed substrate, by example and without limitation, desired surface roughness, desired TSV reveal height, desired substrate thickness, and also a function of actual physical characteristics of the particular substrate including via depths and radial thickness.
• Fig. 9G depicts an exemplary graph plotting surface roughness as a function of flow rate and temperature for a silicon TSV substrate etch, and illustrates the proportional relationship of surface roughness and flow rate and temperature.
• processor 710 executing one or more software modules 730, including preferably etch recipe module 778, can configure process controller 705 to cause the etching apparatus 400 to etch the substrate according to the etch recipe.
• the measurement steps and etching steps are all performed as part of an integrated system defined by complementary devices that are located within a single housing.
• the etching process described in relation to step 840 can include an end-point detection device 500 that is used to more accurately determine the point at which the TSVs are exposed and more accurately control the length of the etching process (duration) and the exposed height of the TSVs.
• the etching device 400 can include an end-point detection device 500 which is an in situ process monitoring system that includes preferably an light emitter 510 and a charge coupled device (CCD) light detector (or other type of detector) 520.
• CCD charge coupled device
• the emitter which is preferably a high intensity light emitter, emits the light on at least a portion of the substrate while within the etch chamber 410 undergoing the etching process and the CCD detects the light reflected off of the substrate.
• the nature of the light reflected off the substrate surface and collected by the CCD, the light signature will vary depending on the composition of the surface. Accordingly, the light reflected by a substrate surface having an overburden will have different properties, or light signature, than the light reflected by a substrate having revealed TSVs.
• the process monitoring system e.g., process controller 705 and the like
• monitors the detected light signature to identify the point at which the light signature is comparable to a reference signature for a substrate having revealed TSVs.
• the detected light signature is analyzed to determine when the substrate has a detected light signature that is indicative of a substrate having revealed TSVs, thereby indicating that the etching process is complete, or nearly complete, and revealed TSVs are present.
• FIG. 10 a flow diagram illustrates a routine 1000 for detecting the point in which TSVs as revealed during the wet etching process step 840 in accordance with at least one embodiment disclosed herein. It should be appreciated that more or fewer operations can be performed than shown in the figures and described herein. These operations can also be performed in a different order than those described herein.
• the process begins at step 1005, where processor 710 executing one or more of software modules 730, including, preferably end point detection module 772, configures process controller 705 to cause light emitter 510 to emit light onto at least a portion of the surface of the particular substrate (sample area) and cause the light detector 520 to detect the color of the light being reflected by the portion of the particular substrate.
• the light detector is a CCD detector, although other alternative light detectors can be used.
• the detector transmits the detected reflected light information to the process controller as further described herein. When etching substrates to reveal TSVs, insufficient light is reflected by the short, thin exposed TSVs at the end of the process under ambient light.
• high intensity LED and ⁇ or colored high intensity light is directed at the substrate to enhance the light signature reflected by the substrate.
• the light signature includes the intensity of one or more particular wavelengths of light that are detected and monitored by the process controller.
• the light signature can include three wavelengths of light (blue, red and green).
• the emitter and/or detector can include one or more light filters such as a red light filter to adjust the characteristics of the light emitted and/or detected.
• the sample area of the particular substrate that is being monitored by the end point detection device can be one or more points on the surface and can be defined by the process controller by default or by the user.
• the plurality of points can each correspond to one or more pixels of the CCD detector and the detected reflected light can be averaged to reduce variations due to noise and distortion from the fluid layer on the substrate.
• the averaged intensity information can be recorded by the process controller and can also be plotted on a chart and displayed on display.
• processor 710 executing one or more of software modules 730, including, preferably end point detection module 772, configures process controller 705 to analyze the light information detected by the CCD detector to compare the light signature of the particular substrate being etched, as detected by the CCD, to a reference light signature.
• processor executing one or more software modules including, preferably end point detection module can configure the process controller to determine a reference light intensity by etching a reference substrate for a set duration and analyzing frames of information collected by the CCD at specified intervals during the etching process and calculate the intensity of three wavelengths of light (blue, red and green) at each frame and noting the intensity of the three wavelengths of light when the TSVs are known to be revealed.
• the process controller can also plot the light intensity data for the reference substrate over time and display the plot to a technician.
• the change in the light signature should be similar for subsequent substrates that are run, provided that subsequent substrates have similar physical properties (e.g., substrate composition and size and TSV composition and size), as would be understood by those skilled in the art. It should also be understood that the particular rate of change of the light signature can vary depending on the particular etch recipe.
• the process controller can detect when the reveal point is reached by analyzing frames of reflected light intensity information collected by the CCD at specified intervals during the etching process and calculate the intensity of three wavelengths of light (blue, red and green) at each frame and compare the light intensity information to the reference light intensity information obtained from the reference substrate.
• the process controller can end the etching process or begin the over etch stage.
• the system can adjust the etch recipe (as described in relation to Process flow 800) for the subsequent substrate and other parameters including but not limited to setting a minimum duration, a maximum duration, the light intensity at the point where TSVs are revealed, and end point of the etch process.
• the end point can be defined as an over etch duration (e.g., how long the etch process should continue after reveal point is detected), in terms of seconds or percentage of process time in order to reveal the TSVs to a desired height.
• the etch rate is identified to be 2 um/min and the light intensity is detected to be a first value when the TSVs are first revealed.
• the system can determine that the etch time for the subsequent run should be approximately 5 minutes, based on reference etch rate and etch depth.
• the CCD detects a light intensity having the first value (the target light intensity) reveal point is detected and the end point is set to have an over etch time of 1 minute in order to achieve a 2um revealed TSV height.
• Fig. 1 1 depicts an exemplary graph of the light intensity data for the duration of a TSV reveal process according to a disclosed embodiment.
• the graph depicts light intensity data for the red 1 1 10, blue 1 1 12 and green 11 14 wavelengths of light for a reference substrate previously etched.
• the intensity data is plotted for the duration of the etching process.
• system 100 which includes the single wafer wet etching apparatus 400 that includes an end point detection device 500 and implements the routine 1000 for detecting the point in which TSVs are revealed provides an automated solution to precisely control the TSV reveal height and adjust etch recipe parameters in real time according to feedback concerning previously etched wafers. Accordingly the system results in higher quality processed substrates, minimizes waste and realizes the benefits generally associated with a single wafer wet etch process.
• the wet etching step incorporating end point detection has been described in relation to process flow 800, it should be understood that single wafer wet etching with end point detection can be performed in the absence of one or more of the other steps of process flow 800. It should be understood that in between each process step discussed in relation to FIG. 8, processor 710 executing one or more of software modules 730 configures process controller 705 to cause wafer transfer device 300 to move the particular wafer between the various stations performing the process steps.
• process controller 705 executing one or more software modules 730, including, database module 780 and display module 780, can configure process controller 705 to collect at least a portion of the data from the various components of system 100, store the collected data in storage 790 and/or memory 720.
• process controller can display the data on display 740, either in raw form, or manipulated form such as a graphical representation as would be understood by those skilled in the art.

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