SEMICON Europa was recently held in Dresden, Germany on Oct. 8-10, 2013. I am extremely grateful to Malcolm Penn, chairman and CEO, Future Horizons for sharing this information with me.
SEMICON Europa included a supplier exhibition where quite a few 450mm wafers were on display. One highlight was a working 450mm FOUP load/unload mechanism, albeit from a Japanese manufacturer. These exhibits did illustrate though that 450mm is for real and no longer a paper exercise. There was also a day-long conference dedicated to 450mm in the largest room. This was crowded throughout the time and a large number of papers were given.
Paul Farrar of G450C began with a presentation about Supply Chain Collaboration for 450mm. His key message was there are 25 different tools delivered to G450C of which 15 are installed in the NFN cleanroom. This number will grow to 42 onsite and 19 offsite by Q1 2015.
He stated that Nikon aims to have a working 193i litho machine in 2H 2014 and install one in Albany in 1H 2015. Farrar also reported a great improvement in wafer quality which now exceed the expected M76 specification, and prime wafers to the M1 spec should be available in Q3 2014. There has also been good progress on wafer reclaim and it is hoped some wafers can be reused up to 10 times, although at least three is the target.
Metrology seems to be one of the most advanced areas with eight different machines already operational. The number of 450mm wafers in their inventory now stands at over 10,000 with these moving between the partners more rapidly. It was immediately noticeable from Farrar’s speech that G450C is now recognising the major contribution Europe is making to 450mm and is looking for more collaborations.
Facilities part of F450C
Peter Csatary of M&W then dealt with the facilities part of G450C, known as F450C. This group consists of:
• M&W (co-ordination)
• Mega Fluid Systems
• Haws Corp.
• Air Liquide
• Ceres Technlogies
• CS Clean Systems
F450C is seen as streamlining communications with the semiconductor companies and their process tool suppliers. The group will focus on four key areas, namely Environmental Footprint, Facility Interface Requirements, Cost and Duration, and Safety and Sustainability.
One interesting point raised was that 450mm equipment is inherently more massive and one suggestion has been that ceiling mounted cranes will be required to install and remove equipment. This of course means that fab roofs would need to be stronger than previously. This topic was discussed at the latest F450C meeting subsequent to this conference.
Another new concept is that of a few standardised 3D templates and adapter plates to allow fab services to be pre-installed before the equipment is placed. An interesting point made elsewhere by M&W is that the current preference is to place a fab where there are already other fabs in existence so that the infrastructure to transport products, materials and services is already in place, as are basic utilities such as power, natural gas and water supply.
However, the scale of the expected utility demand at 450 mm ups the stakes as for example a large 300 mm facility uses about 4 million gallons of water per day, whereas a 450 mm fab will use almost double that, putting immense strain on a location’s infrastructure should there be other fabs in the region. This could affect future site selections.
An outcome of this phenomenon is that the reduction, reclaim and re-use of materials will no longer be driven only by the desire to be a good corporate citizen, but will also be driven by cost control and to ensure availability of required resources such as power, water, specialty gases and chemicals.
The Global 450mm Consortium (G450C) has been driving the effective industry 450mm development. It is co-ordinating test wafer capability supporting development and demonstrating unit process tool performance. The focus is now on improving tools with suppliers to be ready for customer operations.
Giving an update during the recently held Semicon West 2013 at San Francisco, USA, Paul Ferrer, GM, G450C, said that if one looks at the G450C lithography tool roadmap, by 1H-2014, the 300mm coupon, 450mm directed self-assembly and 450mm imprint will be completed. From 2H-2014 to 1H-2015, there will be 193i patterning service at Nikon’s site. Nikon 193i move-in will take place from 1H-2015 to 2H-2016.
Suppliers are developing the 450mm tool set with 10 tools per quarter being delivered to G450C, the global consortium for 450mm fabs. Significant progress has been made in wafer quality and wafer reclaim is almost ready. Automation and carriers are working, and suppliers are co-operating on the key initiatives. Global collaboration is said to be picking up steam.
In the NFX cleanroom, the 450mm OHT is ready for inter-fab transfer. There are nine tools in-fab — two metro, three process, and four stocker, respectively. There will be seven ODD 3Q2013, and 10 tools ODD 4Q2013, respectively.
As for 450mm notchless wafer activities, the key technical results include the backside fiducial marks that have achieved the desired accuracy (3σ = 0.5μm) using existing camera technology. There are design rules of fiducial marks, such as multiple locations (≤ 4) for robustness and speed, different patterns at multiple locations, and off crystal plane, fewer dots and shallower dots to minimize the Si crystal damage.
As for program highlights, there are collected designs from G450C member companies, tool suppliers, and optical detection suppliers. Also, there has been delivery of 300mm test wafers with fiducial marks. G450C has co-ordinated test wafer plans with suppliers. Further, for 450mm silicon wafer readiness, notchless wafers are technically achievable now.
The G450C members include CNSE/Research Foundation, GLOBALFOUNDRIES, Intel, IBM, Samsung and TSMC.
Its a pleasure to talk to Dr. Walden (Wally) C. Rhines, chairman and CEO, Mentor Graphics Corp. On his way to DAC 2013, where he will be giving a ten-minute “Visionary Talk”, he found time to speak with me. First, I asked him given that the global semiconductor industry is entering the sub-20nm era, will it continue to be ‘business as usual’ or ‘it’s going to be different this time’?
Dr. Rhines said: “Every generation has some differences, even though it usually seems like we’ve seen all this before. The primary change that comes with “sub-20nm” is the change in transistor structure to FinFET. This will give designers a boost toward achieving lower power. However, compared to 28nm, there will be a wafer cost penalty to pay for the additional process complexity that also includes two additional levels of resolution enhancement.”
Impact of new transistor structures
How will the new transistor structures impact on design and manufacturing?
According to him, the relatively easy impact on design is related to the simulation of a new device structure; models have already been developed and characterized but will be continuously updated until the processes are stable. More complex are the requirements for place and route and verification; support for “fin grids” and new routing and placement rules has already been implemented by the leading place and route suppliers.
He added: “Most complex is test; FinFET will require transistor-level (or “cell-aware”) design for test to detect failures, rather than just the traditional gate-level stuck-at fault models. Initial results suggest that failure to move to cell-aware ATPG will result in 500 to 1000 DPM parts being shipped to customers.
“Fortunately, “cell-aware” ATPG design tools have been available for about a year and are easily implemented with no additional EDA cost. Finally, there will be manufacturing challenges but, like all manufacturing challenges, they will be attacked, analyzed and resolved as we ramp up more volume.”
Introducing 450mm wafer handling and new lithography
Is it possible to introduce 450mm wafer handling and new lithography successfully at this point in time?
“Yes, of course,” Dr. Rhines said. “However, there are a limited number of companies that have the volume of demand to justify the investment. The wafer diameter transition decision is always a difficult one for the semiconductor manufacturing equipment companies because it is so costly and it requires a minimum volume of machines for a payback. In this case, it will happen. The base of semiconductor manufacturing equipment companies is becoming very concentrated and most of the large ones need the 450mm capability.”
What will be the impact of transistor variability and other physics issues?
As per Dr. Rhines, the impact should be significant. FinFET, for example requires controlling physical characteristics of multiple fins within a narrow range of variability. As geometries shrink, small variations become big percentages. New design challenges are always interesting for engineers but the problems will be overcome relatively quickly.
We are now entering the sub-20nm era. So, will it be business as usual or is it going to be different this time? With DAC 2013 around the corner, I met up with John Chilton, senior VP, Marketing and Strategic Development for Synopsys to find out more regarding the impact of new transistor structures on design and manufacturing, 450mm wafers and the impact of transistor variability.
Impact of new transistor structures on design and manufacturing
First, let us understand what will be the impact of new transistor structures on design and manufacturing.
Chilton said: “Most of the impact is really on the manufacturing end since they are effectively 3D transistors. Traditional lithography methods would not work for manufacturing the tall and thin fins where self-aligned double patterning steps are now required.
“Our broad, production-proven products have all been updated to handle the complexity of FinFETs from both the manufacturing and the designer’s end.
“From the design implementation perspective, the foundries’ and Synopsys’ goal is to provide a transparent adoption process where the methodology (from Metal 1 and above) remains essentially the same as that of previous nodes where products have been updated to handle the process complexity.”
Given the scenario, will it be possible to introduce 450mm wafer handling and new lithography successfully?
According to Chilton: “This is a question best asked of the semiconductor manufacturers and equipment vendors. Our opinion is ‘very likely’.” The semiconductor manufacturers, equipment vendors, and the EDA tool providers have a long history of introducing new technology successfully when the economics of deploying the technology is favorable.
The 300nm wafer deployment was quite complex, but was completed, for example. The introduction of double patterning at 20nm is another recent example in which manufacturers, equipment vendors and EDA companies work together to deploy a new technology.
Impact of transistor variability and other physics issues
Finally, what will be the impact of transistor variability and other physics issues?
Chilton said that as transistor scaling progresses into FinFET technologies and beyond, the variability of device behavior becomes more prominent. There are several sources of device variability.
Random doping fluctuations (RDF) are a result of the statistical nature of the position and the discreteness of the electrical charge of the dopant atoms. Whereas in past technologies the effect of the dopant atoms could be treated as a continuum of charge, FinFETs are so small that the charge distribution of the dopant atoms becomes ‘lumpy’ and variable from one transistor to the next.
With the introduction of metal gates in the advanced CMOS processes, random work function fluctuations arising from the formation of finite-sized metal grains with different lattice orientations have also become important. In this effect, each metal grain in the gate, whose crystalline orientation is random, interacts with the underlying gate dielectric and silicon in a different way, with the consequence that the channel electrons no longer see a uniform gate potential.
The other key sources of variability are due to the random location of traps and the etching and lithography processes which produce slightly different dimensions in critical shapes such as fin width and gate length.
“The impact of these variability sources is evident in the output characteristics of FinFETs and circuits, and the systematic analysis of these effects has become a priority for technology development and IP design teams alike,” he added.
Here is a view from Mike Bryant of Future Horizons, taken from the Enable450 newsletter, for which, I must thank Malcolm Penn, chairman and CEO.
This is a question often asked by journalists and others not directly involved in 450mm technology, and indeed was one of the questions that formed the basis of the SMART 2010/062 report Future Horizons produced for the European Commission.
It is also a question every new 450mm project has to answer in its funding request to the European Commission, and whilst working on the Bridge450 submission we realised the arguments have become rather unclear over time. The following gives some insight and clarity into the question.
In 1970, Gordon Moore re-formulated predictions on computer storage by Turing and others into a simple statement that the number of transistors per unit area of an IC will double every two years for at least the next ten years. This became known as “Moore’s Law” and apart from the occasional hiccup has in fact been followed for the past forty years. Note that Moore never suggested a doubling in density every 18 months, this time period coming from a different statement concerning transistor performance.
Of course, doubling the number of transistors would not be that helpful if the price per unit area also doubled. The semiconductor industry has thus strived to maintain the cost of manufacturing per unit area at a constant price, and analysed over time has done a remarkable job in maintaining this number such that the ASP of logic devices has sat at around $9 per square centimetre for this whole period during which the cost of everything else including the equipment, materials and labour used to make the IC have increased, labour costs in particular increasing by a factor of around five times.
The actual cost of processing a wafer appreciates by around 6 percent per annum due to technology cycle upgrades and insertions, for example in the past the replacement of aluminium interconnects with copper or more recently the move to double patterning for lithography of critical layers. Several approaches have been used to maintain a constant area cost, these being:
Improvements in yield – this obviously reduces wastage and vast improvements have been made in this field though yields are now so good that the problem is more maintaining these levels with each new process node rather than improving them further.
Increasing levels of automation – this is still an area undergoing improvement but again we have entered an area of diminishing returns on the investment required.
Introducing larger wafer sizes – this has been performed on an irregular basis over the history of the semiconductor industry. The increase in surface area reduces many but not all of the processing costs whilst material costs tend to stay fairly constant per unit area. Thus at the 300mm transition the increase in area by 2.25 times gave a cost per unit area reduction of 30 percent, approximately compensating for the increased processing costs acquired over the 90nm and 65nm nodes.
Malcolm Penn, chairman and CEO, Future Horizons, sent me the Enable 450 newsletter. The goal of the Enable 450 is: Co-ordination Action to enable an effective European 450 mm Equipment and Materials Network. Here, I am presenting a bit about the E450EDL – European 450mm Equipment demo line.
The aim of the ENIAC E450EDL key enabling technology pilot project is to continue the engagement of the European semiconductor equipment and materials industry in the 450mm wafer size transition that started with the ENIAC JU EEMI450 initiative and proceeded with subsequent projects funded with public money, amongst others NGC450, SOI450, EEM450PR.
The demo line resulting from this project will be such that it will enable first critical process module development by combining imec infrastructure with tools remaining at the site of the manufacturers (distributed pilot line). Multi-site processing will allow partners to participate in the world first 450mm integration studies and will be enabled by the controlled exchange of 450mm wafers between different sites.
The consortium comprises 41 members (from 11 different European countries) with many SMEs and research institutes. The project is organized in five technical work packages and a work package on management and co-ordination.
In the work package on integration and wafer processing first critical modules will be developed and will demonstrate the feasibility of processing on 450mm wafers. The main objective in the work package on lithography is to develop a wafer stage test-rig, which
can be implemented into the pilot line system. In the work package on front end equipment several tools will be developed such as a plasma ion implant module, a plasma dry etch module, a RTP system and a single wafer cleaning system.
Furthermore, in the dedicated work package on metrology 450mm metrology tool types will be developed for amongst others dielectric film thickness and composition measurements, defect inspection, defect review and analysis, optical critical dimensions (CD), overlay (mask and wafer) and 3D metrology.
Finally, from the work package on wafer handling and automation a set of equipment will be provided to support the demo line operations, and facilitate the R&D dedicated to process and metrology modules.
The project will last 36 months beginning on 1st of October 2013. The budget has been given at €204.6 million of which the ENIAC JU will fund €30.8 million. This project is still considering new members so if you are interested please contact ASML.