In VLSI, physical design (is also known as integrated circuit layout) is a process in which the front end design transfer the structural netlist to the back end design team to convert into a physical layout database which consists of geometrical design information for all the physical layers which is used for interconnections.
DRC is a process where the entire physical design database is checked against design rules. The design layout must adhere to the standards defined by the foundry for manufacturability. DRC was introduced as the lower geometry design technology has evolved vigorously. Understand how design rule checks are applied for 28nm node technology: https://goo.gl/afrNKd
This question is often asked in context to explain how design rule checks can be applied in lower technology nodes on the block and full-chip level.
Design rule checks are nothing but physical checks of metal width, pitch, and spacing requirement for the different layers which depend on different technology nodes. DRC helps in fixing up chip design by checking logical connections of all IC components with design rules and reports, and if they fail, the chip won’t be able to perform specific tasks.
There are some techniques that need to be followed to fix-up DRCs for lower technology nodes. Following are:
Understand how the above-mentioned design rule checks in detail for lower technology nodes: http://bit.ly/2YK8OjR
IR drop is a voltage drop, which affects technology node performance. The power supply in the chip is applied uniformly through metal layers. When voltage is applied to these metal wires, power starts flowing through these metal layers. At that moment, some voltage may get dropped due to the resistance of metal wires and power supply. This drop is called IR drop.
IR drop determines the level of voltage drop in the wires that reaches the pins of standard cells. Value of acceptable IR drop will be decided at the starting of the project and it is one of the factors which determines the performance and reliability of digital IP blocks in lower geometry designs.
If the value of IR drop is more than the acceptable value, it will cause failure of electronic boards due to overheating.
Learn more about IR drop issues and techniques to prevent such issues in the electronic devices.
With the increasing demand of lower technology and low power consumption, eInfochips provides physical design service (RTL-to-GDSII-to-DFT) capabilities.
eInfochips offers DAeRT tool in DFT services for ASIC designs. DAeRT (DFT Automated execution and Reporting Tool) is a framework that gives a platform to create DFT (Design for Testability) flow. It helps to achieve ~100% testability for the ASIC designs.
“DAeRT” supports various DFT methodologies starting with IJTAG/JTAG, MBIST, Scan, ATPG, Pattern Validation, Test Timing Analysis, and Post-Si validation. Know more about the tool in detail:http://bit.ly/2GM32UD
To know more about the impact of 16nm in the IoT era, visit the blog: 5 Proven Tips for Right Time-to-Market at 16nm Lower Technology Node [Infographic]
Power requirements are very critical in modern networking ASICs. In VLSI, advanced techniques like MBIT flops and MIMCAPs can help improve the power and area numbers in 16nm design.
By replacing and merging single bit flops with multi-bit flip-flops using different algorithms, it significantly reduces the area and power numbers for ASIC designs. On-chip MIMCAP (Metal Insulator Metal capacitor) reduces the voltage fluctuation and noise on the power supply, which may have affected signal integrity, reliability, and speed of design. To know more about these advanced technologies, click here.
Physical design implementation challenges include:
To read more about above-mentioned points in implementing a flat design, click here
FinFET has higher drive current in comparison to SOI. Moreover, the strain technology in FinFET can be used to increase carrier mobility. Below are the strengths and weakness of SOI and FinFET in micro-electronics industry:
Read more about the importance of CMOS, SOI and FinFET Technology in the micro-electronics industry.
It is a process of arranging a PCB layout to mitigate difficulties that can come up during PCB fabrication, test, procurement, and assembly functions, which are part of the manufacturing process of an electronic system.
By doing DFM analysis in the PCB layout process, the PCB design cycle time is directly controlled by the designer as a part of the design process. This improves the cycle time, which is needed to iterate through the process of resolving manufacturing violations.
Read more about DFM analysis and its integration into the design system
The top 10 contributing factors to DFM are as follows:
Read about DFM contributing factors in detail.
Semiconductor industry introduced different tools and techniques to control and monitor product quality and performance. Wafer-Level Reliability test is considered as one of those techniques which can be used to provide fast feedback information regarding the reliability of the product in a semiconductor process. This feedback includes process control monitoring (PCM), process qualification, reliability control monitor (RCM), and quarterly monitoring (or re-qualification).
In ASIC design flow, we are performing different stages such as floor planning, power planning, placement, clock tree synthesis, routing and final signoff. Among them, one of the most important stages is building the clock structure for a flip-flop. It is a process of providing the clock connection to the clock pin of a sequential element.
Clock gating is a technique that reduces the switching power dissipation of the clock signals. By inserting a clock gate circuitry, unnecessary clock switching of adders can be avoided during the clock cycles and the stored data remain unchanged. The condition under which a clock signal passes through the clock gate is known as Enable Function, which is the input of the EN port of clock gate circuitry
It is the most popular method for power reduction of clock signals and functional units. A significant fraction of the dynamic power in a chip is in the distribution network of the clock.
Know more about power reduction methodologies in this Low Power Design for Testability
Watch the below 6-minutes video to know how eInfochips helps in m2m IoT application development with low power clock tree synthesis (CTS) optimization in ASIC back-end solution platform.
Electromigration is the gradual displacement of metal atoms in a semiconductor. It occurs when the current density is high enough to cause the drift of metal ions in the direction of the electron flow, and is characterized by the ion flux density. In small die size chip, there is a requirement of high density, which creates a momentum that transfer from moving electrons to the metal ions. These ions will drift in the direction of electrons and result in the displacement of metal atoms, which causes open and short circuits.
Electro-migration is a movement of ions in semiconductor material on chips that engineers need to optimize, especially in lower geometry designs. Integrated circuits need to be reliable and that is why engineers need to understand why they fail. Many issues faced by engineers due to Electromigration include:
Important manual fixes that engineers need to understand in ASIC physical design to overcome the risk of electromigration are:
Physical synthesis begins with a mapped netlist generated by logic synthesis.The netlist describes the logical connections among the physical components (logic gates, macro/IP blocks, I/O pins, etc.). Physical synthesis generates a new optimized netlist and a corresponding layout. Its objectives are to satisfy a combination of timing, area and power.
Read more about FPGA/ASIC Physical Design
Some of the common challenges that engineers encounter in lower geometry design are:
To know more about FinFET technology and its tools, click here.
Double Patterning technique in lower geometry design flow allows the fabs to continue using 193nm wavelength for printing 20nm and below features with the current tools and manufacturing facilities.
There are various processes with which double patterning can be carried out. The important ones are as follows:
In order to know about the Double Patterning techniques, challenges and processes, download a copy of our publication: Double Patterning Technology.
Drain Induced Barrier Lowering (DIBL) is one of the common challenges faced by physical designers when moving from 28nm to 16nm FinFET lower technology node. It is a short-channel effect in MOSFETs, referring to a reduction of the threshold voltage of the transistor as the drain voltage goes high. DIBL has extended beyond the notion of simple threshold adjustment and refers to a number of drain-voltage effects upon MOSFET I-V curves that go beyond description in terms of simple threshold voltage changes.
To know more, read here about various FinFET device issues.
LVS satisfies design rules provided by the fabrication unit and is not responsible for the functionality of the layout. Following errors occur during LVS check in layout design:
Due to continuous reduction in lower-geometry design, some common challenges faced by physical design engineers in lower technology nodes for connected devices include:
To learn more about the above-mentioned challenges, read this blog “Common Challenges of Lower-Technology Nodes for IoT Devices”
In order to work on the digital design for 16nm/22nm technology node, you should use the following tools: mentor graphics calibre, synopsys ICV, quarts, A placer tool, A router tool, Physical verification tool (LVS / DRC / ANT)
With regards to the ongoing trend of lower technology node, the following are the ATPG challenges faced by ASIC engineers:
Read this blog which defines various solutions for improving 16nm performance and power consumption by half.
The team at eInfochips possesses expertise in testing diverse systems for functional behavior, compliance with specifications, performance, and interoperability. The team of engineers has proficiency in various tools and platforms, including:
After floor planning, the tools can help drive RTL synthesis by providing partitioning data, placement data, custom wire load models and control/run scripts.
Front-end HDL based design techniques can be applied for low power consumption design. Read about HDL design techniques in detail to understand how you can use it for significantly reducing power dissipation: https://www.design-reuse.com/articles/20775/hdl-design-low-power.html
Following are the approaches related to front-end HDL based design styles, which can help to reduce power consumption:
Read about the above approaches in details: http://bit.ly/2rNB3w6
The very first and effective step in physical design flow is floor planning. It is the process which helps in structure identification and allocation of space in a way that allows to meet the I/O structure and aspect ratio of design without routing congestion and wastage of die size.
They design approaches for 3D integrated circuits are:
1. Gate level integration: This integration style promises significant wire-length reduction and great flexibility
2. Block level integration: This integration promises to reduce TSV overhead by assigning only a few global interconnects ICs.
Highly memory-intensive physical design implementation brings high complexity in floor planning, resulting into issues related to:
Understand about these challenges in a flat implementation
There are several problems in RTL design that are simply the result of how hardware description languages and synthesis tools evolved. The following are the primary challenges faced by engineers in RTL design that are fundamental to the problem of digital design:
BDD-based methods demonstrate an algebraic solution to debugging single and multiple errors in RTL design verification. Although effective for node design errors, BDDs are limited by memory issues as the design scales.
The following are the four types of placement optimizations in PD flow:
To understand how to overcome placement optimization challenges, check out this case study.
There are different types of DRC violations:
The following approach to be followed by physical design engineer in order to debug DRC violations:
To get the benefits of a lower geometry IC design, semiconductor companies are continuously improving transistor structure, manufacturing techniques, and the tools used for designing future technology nodes.
Several challenges are faced by engineers while scaling down lower technology node below 5nm:
Beyond these, there are various challenges like self-heating, mobility degradation, threshold flattening, etc. Know more about solutions to overcome the problems of scaling the existing silicon FinFET transistor below 5nm node
Factors that need to be addressed for 3D ICs are:
Read more about how 3D Structure is different than 2.5D and effective in semiconductor industry?
The two major reasons behind the need for DFT in VLSI is productivity and quality.
Scan chain is a technique used in DFT (design for testing) to make testing easier by providing an easy way to set and discern every flip-flop in an integrated circuit.
Signal integrity analysis is a technique that analyzes the losses associated with circuit design transmission lines in the area of high speed simulation/design flow.
It is based on PCB transmission lines which allow visibility of signal behavior as they traverse PCB traces, connectors, passive components, etc.
Watch the video to learn about a full featured signal integrity analysis solution in lower technology nodes that includes model extraction, topology generation, and system signal integrity analysis that supports IBIS-AMI.
Clock skew is an important constraint that greatly affects the timing checks. It is the difference in arrival times of the clock signals at any two flip-flops which are interacting with each other.
Engineers adopt several tools to uncover chip design bugs, however, sometimes the bugs are detected too late in the product design lifecycle, after significant investment of time and effort. As engineers struggle with the functionality, correctness and consistency of design, the below major aspects need to be considered:
Know more: http://bit.ly/2GtBRjJ
With proven physical design methodologies, eInfochips has been working on lower geometry design and has delivered multiple tape outs to leading foundries, including TSMC, UMC, GF, Toshiba, TI, and SMIC. eInfochips follows the below-mentioned steps that impact quality, product scheduling, TTM, and business production.With proven physical design methodologies, eInfochips has been working on lower geometry design and has delivered multiple tape outs to leading foundries, including TSMC, UMC, GF, Toshiba, TI, and SMIC. eInfochips follows the below-mentioned steps that impact quality, product scheduling, TTM, and business production.