STRUCTURES, METHODS AND APPLICATIONS FOR ELECTRICAL PULSE ANNEAL PROCESSES
Structures and methods are provided for nanosecond electrical pulse anneal processes. The method of forming an electrostatic discharge (ESD) N+/P+ structure includes forming an N+ diffusion on a substrate and a P+ diffusion on the substrate. The P+ diffusion is in electrical contact with the N+ diffusion. The method further includes forming a device between the N+ diffusion and the P+ diffusion. A method of annealing a structure or material includes applying an electrical pulse across an electrostatic discharge (ESD) N+/P+ structure for a plurality of nanoseconds.
The invention relates to structures and methods for electrical pulse anneal processes and, more particularly, to structures and methods for nanosecond electrical pulse anneal processes.
BACKGROUNDAn annealing process is a heat treatment of a wafer in order to modify properties of materials/structures processed on its surface or in the bulk. For example, annealing is performed on the wafer in order to activate certain species (dopants) of a device such as, for example, associated with a transistor. Depending on the structures or dopants to be annealed, the temperatures necessary for such annealing process can range upwards of 1000° K in some applications and much lower temperatures in other applications.
Annealing can be performed by many different processes. For example, a rapid thermal annealing (RTA) of a wafer can be performed in an oven at high temperatures. In such applications, the entire structure and all materials on the surface are subject to an anneal at the same temperature. However, the anneal temperature for one device or structure may not be applicable for another device or structure, resulting in damage to some devices or structures. This process also has a large temperature ramp up time which increases processing times and costs.
Another annealing process is a laser anneal. In this process, for example, an excimer laser is used to anneal structures/materials on the wafer. This annealing process has a large temperature ramp up time and duration and a non-uniform temperature distribution, which causes limitations for species activation/device performance. For example, the laser has a large beam resolution on the order of about 500 μm2 which makes it impractical for use with smaller areas requiring an anneal. As such, using a laser annealing process may damage structures close to the anneal. Also, as the beam is known to diverge due to reflection, it is possible to cause a non-uniform anneal.
In yet another annealing process, it is possible to place a resistor on a back end of line (BEOL) device in order to anneal a front end of line (FEOL) device. In such applications, though, it is difficult to control the heating and, as a result, it is possible to damage the FEOL device during the annealing process. Typically, such annealing method is only good for large FEOL devices.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.
SUMMARYIn a first aspect of the invention, a method of forming an electrostatic discharge (ESD) N+/P+ structure comprises forming an N+ diffusion on a substrate and a P+ diffusion on the substrate. The P+ diffusion is in electrical contact with the N+ diffusion. The method further comprises forming a device between the N+ diffusion and the P+ diffusion.
In another aspect of the invention, a method of annealing a structure or material comprises applying an electrical pulse across an electrostatic discharge (ESD) N+/P+ structure for a plurality of nanoseconds.
In yet another aspect of the invention, an electrostatic discharge (ESD) N+/P+ structure comprises an N+ diffusion on a substrate and a P+ diffusion on the substrate which is in electrical contact with the N+ diffusion. The structure further includes a device between the N+ diffusion and the P+ diffusion.
In another aspect of the invention, there is a design structure tangibly embodied in a machine readable medium used for designing, manufacturing, or testing an integrated circuit. The design structure includes the method steps and/or structure of the present invention.
The present invention is described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention.
The invention relates to structures and methods for electrical pulse anneal processes and, more particularly, to structures and methods for nanosecond electrical pulse anneal processes. In embodiments, the present invention includes, for example, an electric static discharge (ESD) device which is capable of generating heat for annealing processes. Advantageously, upon the application of an electric pulse, the ESD device can generate localized heat (e.g., about 500° K to 1200° K) to a particular feature of a device for annealing processes. In embodiments, the heat is uniform and can be generated at a small, localized area of about 50 to 100 μm2. In this way, advantageously, the present invention provides structures and methods that can focus heat on a localized area for annealing processes, without damaging surrounding structures. The devices that can benefit from the present invention include all active and passive devices in FEOL, BEOL and the substrate, for example.
In embodiments, contacts 16a and 18a are formed in electrical contact with the N+ diffusion 16 and P+ diffusion 18, respectively. The contacts 16a and 18a can be formed, for example, using a conventional in-sitsu doped poly deposition process. As should be understood, the contacts 16a and 18a are used for supplying an electrical pulse to generate heat across an active region. More specifically, the contact 18a will allow an electric pulse to flow through the anode (P+ diffusion 18) of the structure 10; whereas, the contact 16a will allow the electric pulse to flow out of the cathode (N+ diffusion 16). In an optional step, a metal deposition process (removable) can be performed on the structure.
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In operation, an electrical pulse is applied to the contact 18a of the structure which, in turn, will very quickly produce heat across the ESD N+/P+ body diode structure 10. More particularly, an electrical pulse of about 100 ns to about 500 ns can be applied across the ESD N+/P+ body diode structure 10 in order to generate a localized heat on the order of about, for example, 500° K to about 1200° K, depending on the area of the active area 20 and the duration of the electrical pulse. In embodiments, the electrical pulse is capable of generating a uniform, localized heat to a very precise location, e.g., within an area of 50 to 100 μm2. The localized heat will anneal a very small area, e.g. a doped region to activate dopants, which would not otherwise be possible with laser anneal or back end of line (BEOL) devices. Also, as the heat is very localized, other regions of the substrate will not be exposed to more than a maximum allowable temperature (e.g., a temperature lower than the annealing temperature) during the entire processing of the wafer, thus ensuring that no damage will be sustained to other devices or regions of the device.
In further examples, a 25 milliamps electrical pulse can be applied to a 100 micron by 10 micron device. Also, in still a further example, 2.5 milliamps electrical pulse can be applied to a 100 micron by 100 micron device. Further examples are also contemplated by the present invention, depending on the particular area of the device. The present invention can also be applied for FEOL or BEOL structures. In any of these illustrative examples, the electrical pulse can have a duration of about 100 ns to about 500 ns, and results in a uniform, localized anneal.
In embodiments, contacts 16a and 18a are formed in electrical contact with the N+ diffusion 16 and P+ diffusion 18, respectively. The contacts 16a and 18a can be formed, for example, using a conventional in-sitsu doped poly deposition process as discussed above. As should be understood, the contacts 16a and 18a are used for supplying an electrical pulse to generate heat across an active region. More specifically, the contact 18a will allow an electric pulse to flow through the anode (P+ diffusion 18) of the structure 10; whereas, the contact 16a will allow the electric pulse to flow out of the cathode (N+ diffusion 16). In an optional step, a metal deposition process (removable) can be performed on the structure. As should now be understood by those of skill in the art, the N+ diffusion 16 and the P+ diffusion 18 form an ESD N+/P+ body diode structure.
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Design flow 900 may vary depending on the type of representation being designed. For example, a design flow 900 for building an application specific IC (ASIC) may differ from a design flow 900 for designing a standard component or from a design flow 900 for instantiating the design into a programmable array, for example a programmable gate array (PGA) or a field programmable gate array (FPGA) offered by Altera® Inc. or Xilinx® Inc.
Design process 910 preferably employs and incorporates hardware and/or software modules for synthesizing, translating, or otherwise processing a design/simulation functional equivalent of the components, circuits, devices, or logic structures shown in
Design process 910 may include hardware and software modules for processing a variety of input data structure types including netlist 980. Such data structure types may reside, for example, within library elements 930 and include a set of commonly used elements, circuits, and devices, including models, layouts, and symbolic representations, for a given manufacturing technology (e.g., different technology nodes, 32 nm, 45 nm, 90 nm, etc.). The data structure types may further include design specifications 940, characterization data 950, verification data 960, design rules 970, and test data files 985 which may include input test patterns, output test results, and other testing information. Design process 910 may further include, for example, standard mechanical design processes such as stress analysis, thermal analysis, mechanical event simulation, process simulation for operations such as casting, molding, and die press forming, etc. One of ordinary skill in the art of mechanical design can appreciate the extent of possible mechanical design tools and applications used in design process 910 without deviating from the scope and spirit of the invention. Design process 910 may also include modules for performing standard circuit design processes such as timing analysis, verification, design rule checking, place and route operations, etc.
Design process 910 employs and incorporates logic and physical design tools such as HDL compilers and simulation model build tools to process design structure 920 together with some or all of the depicted supporting data structures along with any additional mechanical design or data (if applicable), to generate a second design structure 990. Design structure 990 resides on a storage medium or programmable gate array in a data format used for the exchange of data of mechanical devices and structures. Similar to design structure 920, design structure 990 preferably comprises one or more files, data structures, or other computer-encoded data or instructions that reside on transmission or data storage media and that when processed by an ECAD system generate a logically or otherwise functionally equivalent form of one or more of the embodiments of the invention shown in
Design structure 990 may also employ a data format used for the exchange of layout data of integrated circuits and/or symbolic data format. Design structure 990 may comprise information such as, for example, symbolic data, map files, test data files, design content files, manufacturing data, layout parameters, wires, levels of metal, vias, shapes, data for routing through the manufacturing line, and any other data required by a manufacturer or other designer/developer to produce a device or structure as described above and shown in
The method as described above is used in the fabrication of integrated circuit chips. The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below, where applicable, are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. Accordingly, while the invention has been described in terms of embodiments, those of skill in the art will recognize that the invention can be practiced with modifications and in the spirit and scope of the appended claims.
Claims
1. A structure comprising:
- an N+ diffusion on a substrate;
- a P+ diffusion on the substrate and in direct electrical and physical contact with the N+ diffusion, thereby forming an ESD diode; and
- a device between the N+ diffusion and the P+ diffusion,
- wherein the N+ diffusion and the P+ diffusion are in a side by side relationship.
2. The structure of claim 1, further comprising a contact on the P+ diffusion and a contact on the N+ diffusion to provide an electrical pulse to the P+ diffusion and allow the electrical pulse to flow out of the N+ diffusion, respectively.
3. The structure of claim 1, wherein the N+ diffusion and the P+ diffusion form an ESD N+/P+ structure.
4. The structure of claim 1, wherein the N+ diffusion and the P+ diffusion are formed on a BOX layer formed on the substrate.
5. The structure of claim 4, wherein the N+ diffusion acts as a cathode and the P+ diffusion acts as an anode.
6. The structure of claim 5, further comprising contacts for supplying an electrical pulse to generate heat across an active region.
7. The structure of claim 6, wherein a first of the contacts allows an electric pulse to flow through the anode and a second of the contacts allows the electric pulse to flow out of the cathode.
8. The structure of claim 7, wherein the device is an active device formed in electrical contact with the N+ diffusion and P+ diffusion.
9. The structure of claim 7, wherein the device is a passive device formed in electrical contact with the N+ diffusion and P+ diffusion.
10. An electrostatic discharge (ESD) N+/P+ structure comprising:
- an N+ diffusion on a substrate;
- a P+ diffusion on the substrate and in electrical contact with the N+ diffusion; and
- a device between the N+ diffusion and the P+ diffusion,
- wherein the N+ diffusion and the P+ diffusion are in a side by side relationship, and the device is a single device between the N+ diffusion and the P+ diffusion.
11. The structure of claim 10, further comprising a contact on the P+ diffusion and a contact on the N+ diffusion to provide an electrical pulse to the P+ diffusion and allow the electrical pulse to flow out of the N+ diffusion, respectively.
12. The structure of claim 10, wherein the N+ diffusion and the P+ diffusion form an ESD N+/P+ structure.
13. The structure of claim 10, wherein the N+ diffusion and the P+ diffusion are formed on a BOX layer formed on the substrate.
14. The structure of claim 13, wherein the N+ diffusion acts as a cathode and the P+ diffusion acts as an anode.
15. The structure of claim 14, further comprising contacts for supplying an electrical pulse to generate heat across an active region.
16. The structure of claim 15, wherein a first of the contacts allows an electric pulse to flow through the anode and a second of the contacts allows the electric pulse to flow out of the cathode.
17. The structure of claim 16, wherein the device is an active device formed in electrical contact with the N+ diffusion and P+ diffusion.
18. The structure of claim 16, wherein the device is a passive device formed in electrical contact with the N+ diffusion and P+ diffusion.
Type: Application
Filed: Feb 28, 2019
Publication Date: Jun 27, 2019
Inventors: Michel J. ABOU-KHALIL (Essex Junction, VT), Robert J. GAUTHIER, JR. (Hinesburg, VT), Tom C. LEE (Essex Junction, VT), Junjun LI (Cupertino, CA), Souvick MITRA (Essex Junction, VT), Christopher S. PUTNAM (Hinesburg, VT), Robert R. ROBISON (Colchester, VT)
Application Number: 16/288,920