Abstract:
A device and method to control the heating of an IC chip in a wafer form for measuring various parameters associated therewith are provided. Embodiments include a device having a silicon layer with an upper surface, and on a plastic carrier; a plurality of devices in the silicon layer and electrically coupled through the upper surface to a test control system; a through silicon via (TSV) extending into the silicon layer; and a parallel heating structure adjacent to the plurality of devices electrically coupled to the test control system.

Description:
TECHNICAL FIELD 
     The present disclosure demonstrates a novel technique to measure various parameters in integrated circuits and particularly to quantify defects due to through silicon vias (TSVs). This disclosure works for all CMOS nodes, like for example 20 nanometer (nm), 14 nm technology nodes and beyond. 
     BACKGROUND 
     Generally, a plurality of devices (e.g., transistors, diodes, etc.) are designed and embedded into an integrated circuit (IC) chip/die, which may be placed into a package (e.g., plastic casing) or used as a bare die for placement onto a printed circuit board (PCB) of an electronic device. However, due to limited space availability on the PCBs, manufacturers of the IC chips are integrating multiple IC chips into a single vertical three-dimensional (3D) IC chip stacks, which require a much smaller footprint on a PCB. For example, a 3D IC chip stack may include several logic, memory, analog, or similar IC chips that may be connected to each other by using of TSV architecture. Typically, TSVs are vertical vias etched in a silicon layer and filled with a conducting material (e.g., copper), which provides connectivity for communication signals and voltage supply between the vertically stacked IC chips. Adoption of 3D IC chip stacking is increasingly being viewed as an alternative or addition to traditional technology node scaling at the transistor level, which may provide solutions to meet performance, power, and bandwidth requirements of various electronic devices. 
       FIGS. 1A and 1B  schematically illustrate example of IC chip structure including a plurality of TSVs.  FIG. 1A  illustrates an example of 3D IC chip stack  100  that includes IC chips  101 ,  103 , and  105 . These chips are “sandwiched” and interconnected by interconnection layers  107  (e.g., including micro-bumps) to form a vertical stack, which is connected to a package substrate  109 . As illustrated, the IC chips  101  and  103  may include a front metal layer  111  and a back metal layer  113 , but the IC chip  105  includes only a front metal layer  111 , wherein each of the metal layers  111  and  113  may represent a plurality of metal layers M-1 through M-n. Additionally, the IC chips  101 ,  103 , and  105  include a device layer  115  and a silicon layer  117 .  FIG. 1B  illustrates the single IC chip  101 , which still includes the plurality of TSVs  119 . In various scenarios, the TSVs may be implemented by use of different IC manufacturing processes; however, implementation of TSVs in 3D IC chip stacks, as well as in a single IC chip, can cause defects in the IC chip stack or in the single IC chip. For instance, implementation of the TSVs may introduce defects affecting the electrical performance of components/devices embedded in an IC chip, or the TSVs may impact the reliability of an IC chip stack. For the sake of an example, fully processed wafers with chips manufactured on top are lapped and their thickness reduced down to few microns. In some other instances, the defects may be due to a back-end-of-line (BEOL) process where an IC chip stack is formed or due to mounting of an IC chip wafer (e.g., including a plurality of IC chips) onto a plastic substrate. To quantify possible defects, various parameters at an IC chip may be measured and characterized while the IC chip wafer is cycled through different temperatures and defects may be more visible in a specific temperature range. However, increasing the temperature of an entire chip wafer may be time consuming, and the plastic substrate/film of a thinned IC chip wafer (e.g., 50 micrometer) may not be able to withstand higher temperatures (e.g., more than 50° Celsius (C)) of a test environment. 
     Therefore, a methodology and circuitry enabling both the defects detection due to TSVs processing damage as well as measuring various parameters associated with an IC chip on a plastic carrier is highly needed. 
     SUMMARY 
     An aspect of the present disclosure is the implementation of a circuit to control the heating of an IC chip. The circuit being integrated into the IC chip at wafer level for measuring various parameters associated therewith. 
     Another aspect of the present disclosure is the establishment of a method for the implementation of a circuit to control the heating of an IC chip, the circuit being integrated into the IC chip at wafer level for measuring various parameters associated therewith. 
     Additional aspects and other features of the present disclosure will be set forth in the description which follows and in part will be apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the present disclosure. The advantages of the present disclosure may be realized and obtained as particularly pointed out in the appended claims. 
     According to the present disclosure, some technical effects may be achieved in part by a device including: a silicon layer having an upper surface, and on a plastic carrier, a plurality of devices in the silicon layer and electrically coupled through the upper surface to a test control system, a TSV extending into the silicon layer; and a parallel heating structure adjacent to the plurality of devices electrically coupled to the test control system. Some aspects further include a device where the parallel heating structure includes a plurality of heating elements arranged in parallel. Further aspects include a device where the heating elements are formed in a metal layer of a plurality of metal layers over the first silicon layer. 
     Other aspects include a plurality of control elements each electrically coupled to a different one of the devices and to the test control system. In another aspect the test control system includes a multiplexing controller unit and a plurality of voltage and current sources. In a further aspect, the test control system is capable of measuring current transfer through each of the plurality of devices. In addition, the test control system is capable in varying and controlling a temperature level at each of the plurality of heating elements. In one aspect, the plurality of devices includes diodes. 
     In some aspects of the present disclosure, the proposed method has several advantages, including a precise detection capability of a current transfer through a plurality of devices in a semiconductor IC chip on a plastic carrier, localized variation and control capacity of a temperature level in the semiconductor IC chip, and able to detect even a small change in the current transfer at the varied temperature level. In another aspect, the varying of the temperature is effectuated via a parallel heating structure including a plurality of heating elements arranged in parallel. In some aspects, the heating elements are in a metal layer of a plurality of metal layers in the semiconductor IC chip. In one aspect, the method includes controlled increase of the local temperature of the semiconductor IC chip in a range of about 25° C. to about 300° C. 
     In a further aspect, the method includes electrically coupling of each of a plurality of control elements to a different one of the devices and to a test control system. In some aspects, the method includes addressing the plurality of devices, via the test control system, and by a coding scheme including row and column indicators associated with each of the devices. In one aspect, the plurality of devices includes diodes. 
     In other aspects of the present disclosure, the method includes providing a silicon layer having an upper surface, and on a plastic carrier, providing a plurality of devices in the silicon layer, electrically coupling the devices through the upper surface to a test control system, providing a TSV extending into the silicon layer, arranging heating elements in parallel in one or more metal layers, the heating elements being adjacent to the plurality of devices, electrically coupling of the heating elements to the test control system, detecting a current transfer through the plurality of devices, locally varying a temperature level of the plurality of devices, and detecting a change in the current transfer at the varied temperature level. 
     Additional aspects and technical effects of the present disclosure will become readily apparent to those skilled in the art from the following detailed description wherein embodiments of the present disclosure are described simply by way of illustration of the best mode contemplated to carry out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawing and in which like reference numerals refer to similar elements and in which: 
         FIGS. 1A and 1B  schematically illustrate example of IC chip structures including a plurality of TSVs; 
         FIG. 2  illustrates a block diagram of a device and a TSV in an IC chip, in accordance with an exemplary embodiment; and 
         FIG. 3  schematically illustrates a circuit for testing an IC chip, in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     For the purposes of clarity, in the following description, numerous specific details are set forth to provide a thorough understanding of exemplary embodiments. It should be apparent, however, that exemplary embodiments may be practiced without these specific details or with an equivalent arrangement. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring exemplary embodiments. In addition, unless otherwise indicated, all numbers expressing quantities, ratios, and numerical properties of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” 
     The present disclosure addresses and solves the inability problem of a plastic carrier to withstand the high temperatures needed to detect potential defects in any IC chip during a wafer level testing of, for example thinned wafers, where these defects may be due to TSVs used for connecting a plurality of IC chips to each other. The present disclosure addresses and solves such problems, for instance, by, inter alia, measuring various parameters at the IC chip while locally varying and controlling the temperature at a plurality of devices at the IC chip. 
       FIG. 2  illustrates a block diagram of a device, a TSV, and a heating element in an IC chip, in accordance with an exemplary embodiment. Diagram  200  includes an electronic device  201  (e.g., a diode, transistor, capacitor, etc.) in a semiconductor layer  115 , where the device  201 , a diode for example, has a P+ contact  203  and an N+ contact  205 , which are further connected to their respective electrical contacts  207  and  209 , for example, at a metal-1 (M-1) layer. Further, the semiconductor layer  115  includes shallow trench isolation (STI) regions  211  and  213  that are to prevent electrical leakage current (Ampere=I) between adjacent devices (e.g., the device  201  and another device) on the same semiconductor layer  115 . Furthermore, the diagram  200  depicts a TSV  119  that is formed and extends into the semiconductor layer  115 , where the TSV may be extended through the semiconductor layer  115  to provide connectivity from/to other substrate layers above or below the device  201 . For example, the TSV  119  may be used to provide signaling connections between a microprocessor IC chip that may be below the semiconductor layer  115  and a memory IC chip that may above the semiconductor layer  115 . Additionally, the diagram  200  depicts a metal layer  111 , which may provide electrical connectivity among a plurality of metal layers above or below the device  201 . As mentioned, to detect potential defects  215  in an IC chip, the IC chip may be tested at different temperatures (e.g., 25 to 300° C.) during a front-end-of-line (FEOL) process where various functional tests (e.g., transistor characteristics) on an IC chip may be performed. In some instances, latent defects in an IC chip may become active or present higher levels of malfunction at higher temperature levels. Additionally, the tests may include conditions to reflect variations in the manufacturing process (e.g., process corners) as well as an operating voltage range for the IC chip. For example, a diode-like device may be utilized to study defects in an IC chip since a diode can simulate functional characteristics of a metal-oxide-semiconductor field-effect transistor (MOSFET) device under similar conditions. Specifically, the current conduction mechanism in a diode is limited by electron-hole recombination, such that in the presence of a bulk defect (e.g., defects  215 ), the current conduction would increase. Furthermore, the defects would be easier to detect as the temperature of each IC chip is increased (e.g., 50 to 125° C.) by controlling its respective heating element that, for example, may be in a metal-2 (M-2) layer. 
     In the reliability field of negative bias temperature instability, where defects are generated in PMOS devices at high electric field and high temperature (e.g., 125° C.), solutions including use of local heaters have been demonstrated. In some instances, local-heater solutions involving diode junctions or resistor-like structures at interconnect level have been demonstrated. In one example, BEOL metallization, commonly used as local interconnect for devices and circuits, is used as the local heater. In this case a local resistor-like heater is interconnected on top of the devices or circuits of interest thus being able to optimally heat any device under test even in presence of poorly conductive FINFET architectures. Additionally, it is noted that these interconnect lines are typically capable to sustain heating power (e.g., a milliwatt) needed to bring local temperature into the desired levels without suffering themselves reliability issues (e.g., electromigration) as well as being robust against process-induced damage by a TSV itself, (local cracks, flexibility, etc.) 
       FIG. 3  schematically illustrates a circuit for testing an IC chip, in accordance with an exemplary embodiment. In  FIG. 3 , circuit  300  includes a plurality of TSVs  119 , heating elements  301  (e.g., in the front metal layer  111 ), and devices (e.g., diodes)  303 , wherein the heating elements  301  and the devices  303  are electrically coupled to a source measure unit (SMU) device  305 . In some instances, a plurality of SMUs  305 ,  305   a ,  305   b ,  305   c , or the like, may be utilized to perform various functions, e.g., provide/measure current or voltage, control/measure temperatures, etc., for a testing of the devices  303 . Typically, an SMU is a versatile device that can be utilized to provide and control precise levels of voltage or current to an electronic device and simultaneously measure voltage or current at that device. The SMU device  305  can be used together with a multiplexer  307  for providing control signals to the devices  303  via control elements  309  (e.g., “AND” gates), respectively. Importantly, this solution enables the fast collection of a large sample statistics for a proper assessment of process variability and process damage induced by, for example, TSV processing or similar. Additionally, the SMU devices  305   a  and  305   b  include current sources  311  and  313  to provide current to the devices  303  via the control elements  309 . In one example, the current sources  311  and  313  can provide two different currents of a known ratio to control elements  309   a  and  309   b , respectively, where the SMU device  305 ,  305   a , or  305   b  can measure voltages developed across devices  303   a  and  303   b  and use those voltages to calculate respective temperatures across the devices  303   a  and  303   b . Furthermore, the heating elements  301  are also coupled to the SMU device  305 . In one example, to determine statistical measurement data, the SMU device  305   c  can cause an increase in the temperature of the multiple devices  303  via their respective heating elements  301  while the devices can be addressed by the SMU device  305  in a memory-like coding with row/column indicators associated with each device  303 . In this example the circuit  300  includes a 32×32 matrix of TSVs and devices  303  that can be addressed by the multiplexer  307 . It is noted that in addition to characterizing diodes in an IC chip, the circuit  300  may be utilized in a similar fashion to test or characterize MOSFETs, ring oscillators, or the like devices where TSV architecture is utilized. 
     Advantages of the design of  FIG. 3  include fast detection of defects and reliability issues in an IC chip that is utilizing TSV architecture in a statistically sound method, wherein a plurality of IC chips may be tested/characterized with different device geometries and manufacturing/fabrication process corners. 
     The embodiments of the present disclosure can achieve several technical effects, including improved detection of defects and reliability issues in an IC chip that is utilizing TSV architecture. Furthermore, the embodiments enjoy utility in various industrial applications as, for example, microprocessors, smart phones, mobile phones, cellular handsets, set-top boxes, DVD recorders and players, automotive navigation, printers and peripherals, networking and telecom equipment, gaming systems, digital cameras, or other devices utilizing logic or high-voltage technology nodes. The present disclosure therefore enjoys industrial applicability in any of various types of highly integrated semiconductor devices, including devices that use SRAM memory cells (e.g., liquid crystal display (LCD) drivers, synchronous random access memories (SRAM), digital processors, etc.) 
     In the preceding description, the present disclosure is described with reference to specifically exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present disclosure, as set forth in the claims. The specification and drawings are, accordingly, to be regarded as illustrative and not as restrictive. It is understood that the present disclosure is capable of using various other combinations and embodiments and is capable of any changes or modifications within the scope of the inventive concept as expressed herein.