The process of producing and sending the layout design file (generally in GDS or OASIS format) to the foundry, for the final fabrication, is termed ‘tapeout’. Being the final step for the Physical Design team, tapeout brings a sigh of relief but before this, a lot of brainstorming is involved.

Before closing the final design, there are several signoffs required- like physical signoff, IR signoff, timing signoff, etc. to get to a closer state of the final layout, and all these feats are accomplished in the Engineering Change of Order phase, generally termed as ECO.

In this article, we have highlighted the various aspects of the ECO phase.

The ECO Phase

In VLSI Designs, ECO is the practice of introducing logic directly into the gate-level Netlist that corresponds with the change happening in RTL. This helps in repairing any mistake or implementing change requests from the end client and also accommodating last-minute revisions.

In this phase of design, all signoff checks are closed which were open in the Place and Route stage. Generally in PnR the DRC and IR are made closable but the final closing is made only in the ECO stage. Closing the PnR implementation activities ECO solves all the open issues. So the design engineers need good timings and sound DRC numbers to gain confidence regarding the solvability of all issues in the ECO phase.

The ECO Cycle

ECO Cycle is the process of analyzing each check specifically that is required to be closed. With the special proprietary tools for signoffs and testing, team InSemi easily analyzes the issues and gets to know the required changes that can help close the issue, easily. A special ECO file is developed to record all those changes. As the InSemi design engineers get the final ECO file, the information is then implemented on the PnR database on which the analysis has been done. After such implementation, the updated database is analyzed for the next ECO file generation and implementation. Such a cycle repeats for all the open issues and one by one all are closed for the final layout.

In a nutshell, the ECO Cycle can be summed in the following four main steps:

  1. Analyzing the design issue 
  2. Generating ECO File for it
  3. Implementing it in the database
  4. Save the database for the next ECO Cycle 

ECO Implementation

Implementation of the ECO process, in general, is done in the batch mode of the tool. Fillers are deleted first and then the sourced ECO file is used to make the requisite changes. After this, there might be the need for changes in cell sizes or the addition/removal of some cells. Such refinement of the placement is done by the ECO route. Any overlapping or incorrect routing of cells is also taken care of by this. The updated database is then saved for the next ECO cycle.

Events Requiring EOC the most

In the electronics world, there are plethoras of events, especially the changes in work patterns that make EOC imperative. Broadly speaking those events can be categorized into three main parts:

1. Changes in Products
Even after the final product design, there might be a need to make some changes for varied reasons. Even after some time, the existing products might need hardware changes to keep up the pace with technological advances. Whatever the reason be, whenever any change would be required, EOC will also be required.

2. Changes in Regulations
The regulatory compliances or the benchmarks to guide the product design, development, and manufacturing, are most prone to amendments at any point of the product lifecycle. When any new regulation or industrial standard is modified then the process & products also need to be changed and for that EOC comes into play.

3. Changes in Work Patterns 

The documents under the control of the organization ensure the compliance and best industry practices of the device. These work documents also ascertain that all the job functions involved in the design or development process fulfil their duties correctly. Modifications in templates or work instructions actuate the ECO need.

Getting the Best out of EOC

As discussed in the EOC cycle and implementation part, the EOC process requires a fair amount of documentation, related reviews, and associated approvals. Many times all this doesn’t play with the right pace as the design team would require.

For real, EOC is highly vulnerable to bottlenecks in the organization, leading to time wastage and frustrating the engineers as well. The simple Quality Management Tools have various limitations including lack of visibility into change effects, the long approval time for the EOC cycle, and inefficient document control.

Countering all this, team InSemi proudly possesses an advanced approach, so that the best can be got from the EOC process. In the EOC context, what simple makes us the best includes:

1. Real-Time Visibility into the Changes

The dedicated change management workflow helps accumulate real-time data from other subsystems. Our closed-loop traceability of all data, processes, and activities, visualizes the connections between documents and records; which helps understand the change impact better.

2. Streamlined Reviews and Approval

At InSemi, the associated personnel gets full visibility into the ECO process and all get to know who is reviewing the process and how long they have been into with this. This facilitates efficient and timely approval, which is completely data-driven.

3. Change Management System

Our smart Change Management System is efficiently integrated with data documents. This helps identify every related document and the quality event impacted by the changes. This reduces the possibilities of human errors and lessens the chances of related reworks in executing a change.

Changes are an inevitable part of life, but it is in our hands to transform them from a stressfully chaotic responsibility to an opportunity for improvements. But to transform their ‘theme’ this way, there is a need for a specialized and efficient approach to change management. We might not help you transform your changes in your personal life but in the Physical Designs and EOC, team InSemi is always there for the overall betterment!