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Posts Tagged ‘Photomask’

EUV Leads the Next Generation Litho Race

Friday, October 20th, 2017

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As previously reported by Solid State Technology, the eBeam Initiative recently reported the results of its lithography perceptions and mask-makers’ surveys. After the survey results were presented at the 2017 Photomask Technology Symposium, Aki Fujimura, CEO of D2S, the managing company sponsor of the eBeam Initiative, spoke with Solid State Technology about the survey results and current challenges in advanced lithography.

The Figure shows the consensus opinions of 75 luminaries from 40 companies who provided inputs to the perceptions survey regarding which Next-Generation Lithography (NGL) technologies will be used in volume manufacturing over the next few years. “We don’t want to interpret these data too much, but at the same time the information should be representative because people will be making business decisions based on this,” said Fujimura.

Figure 1

Confidence in Extreme Ultra-Violet (EUV) lithography is now strong, with 79 percent of respondents predicting it will be used in HVM by the end of 2021, a huge increase from 33 percent just three years ago. Another indication of aggregate confidence in EUVL technology readiness is that only 7 percent of respondents thought that “actinic mask inspection” would never be used in manufacturing, significantly reduced from 22 percent just last year.

“Asking luminaries is very meaningful, and obviously the answers are highly correlated with where the industry will be spending on technologies,” explained Fujimura. “The predictability of these sorts of things is very high. In particular in an industry with confidentiality issue, what people ‘think’ is going to happen typically reflects what they know but cannot say.”

Fujimura sees EUVL technology receiving most of the investment for next-generation lithography (NGL), “Because EUV is a universal technology. Whether you’re a memory or logic maker it’s useful for all applications. Whereas nano-imprint is only useful for defect-resistant designs like memory.”

Vivek Bakshi’s recent blog post details the current status of EUVL technology evolution. With practical limits on the source-power, many organization are looking at ways to increase the sensitivity of photoresist so as to increases the throughput of EUVL processes. Unfortunately, the physics and chemistry of photoresists means that there are inherent trade-offs between the best Resolution and Line-width-roughness (LWR) and Sensitivity, termed the “RLS triangle”.

The Critical Gases and Materials Group (CGMG) of SEMI held a recent webinar in which Greg MacIntyre, Imec’s director of patterning, discussed the inherent tradeoffs within the RLS triangle when attempting to create the smallest possible features with a single lithographic exposure. Since the resist sensitivity directly correlates to the maximum throughput of the lithographic exposure tool, there are various tricks used to improve the resolution and roughness at a given sensitivity:  optimized underlayer reflections for exposures, smoothing materials for post-develop, and hard-masks for etch integration.

Mask-Making Metrics

The business dynamics of making photomasks provides leading indicators of the IC fab industry’s technology directions. A lot of work has been devoted to keeping mask write times consistent compared with last year, while the average complexity of masks continues to increase with Reticle Enhancement Technologies (RET) to extend the resolution of optical lithography. Even with write times equal, the average mask turn-around time (TAT) is significantly greater for more critical layers, approaching 12 days for 7nm- to 10nm-node masks.

“A lot of the increase in mask TAT is coming from the data-preparation time,” explained Fujimura. “This is important for the economics and the logistics of mask shops.” The weighted average of mask data preparation time reported in the survey is significantly greater for finer masks, exceeding 21 hours for 7nm- to 10nm-nodes. Data per mask continues to increase; the most dense mask now averages 0.94 TB, and the most dense mask single mask takes 2.2 TB.

—E.K.

Solid State Watch: April 10-16, 2015

Friday, April 17th, 2015
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The Week in Review: September 26, 2014

Friday, September 26th, 2014

NANIUM announced it has successfully launched the industry’s largest Wafer-Level Chip Scale Package (WLCSP) in volume.

Pixelligent Technologies announced that it has been selected for a Department of Energy (DOE) solid-state-lighting award to support the continued development of its OLED lighting application.

Extreme-ultraviolet lithography was a leading topic at the SPIE Photomask Technology conference and exhibition, held September 16-17-18 in Monterey, Calif., yet it wasn’t the only topic discussed and examined.

SiTime Corporation, a MEMS analog semiconductor company, this week announced that it has closed $25 million in new financing, which consisted of a combination of structured debt facility of $15 million provided by Capital IP Investment Partners LLC and strategic equity investment from other investors.

Silicon Motion elected Han-Ping Shieh to its Board of Directors.

SPIE Photomask Technology Wrap-up

Tuesday, September 23rd, 2014

Extreme-ultraviolet lithography was a leading topic at the SPIE Photomask Technology conference and exhibition, held September 16-17-18 in Monterey, Calif., yet it wasn’t the only topic discussed and examined. Mask patterning, materials and process, metrology, and simulation, optical proximity correction (OPC), and mask data preparation were extensively covered in conference sessions and poster presentations.

Even with the wide variety of topics on offer at the Monterey Conference Center, many discussions circled back to EUV lithography. After years of its being hailed as the “magic bullet” in semiconductor manufacturing, industry executives and engineers are concerned that the technology will have a limited window of usefulness. Its continued delays have led some to write it off for the 10-nanometer and 7-nanometer process nodes.

EUV photomasks were the subject of three conference sessions and the focus of seven posters. There were four posters devoted to photomask inspection, an area of increasing concern as detecting and locating defects in a mask gets more difficult with existing technology.

The conference opened Tuesday, Sept. 16, with the keynote presentation by Martin van den Brink, the president and chief technology officer of ASML Holding. His talk, titled “Many Ways to Shrink: The Right Moves to 10 Nanometer and Beyond,” was clearly meant to provide some reassurance to the attendees that progress is being made with EUV.

He reported his company’s “30 percent improvement in overlay and focus” with its EUV systems in development. ASML has shipped six EUV systems to companies participating in the technology’s development (presumably including Intel, Samsung Electronics, and Taiwan Semiconductor Manufacturing, which have made equity investments in ASML), and it has five more being integrated at present, van den Brink said.

The light source being developed by ASML’s Cymer subsidiary has achieved an output of 77 watts, he said, and the company expects to raise that to 81 watts by the end of 2014. The key figure, however, remains 100 watts, which would enable the volume production of 1,000 wafers per day. No timeline on that goal was offered.

The ASML executive predicted that chips with 10nm features would mostly be fabricated with immersion lithography systems, with EUV handling the most critical layers. For 7nm chips, immersion lithography systems will need 34 steps to complete the patterning of the chip design, van den Brink said. At that process node, EUV will need only nine lithography steps to get the job done, he added.

Among other advances, EUV will require actinic mask inspection tools, according to van den Brink. Other speakers at the conference stressed this future requirement, while emphasizing that it is several years away in implementation.

Mask making is moving from detecting microscopic defects to an era of mesoscopic defects, according to Yalin Xiong of KLA-Tencor. Speaking during the “Mask Complexity: How to Solve the Issues?” panel discussion on Thursday, Sept. 18, Xiong said actinic mask inspection will be “available only later, and it’s going to be costly.” He predicted actinic tools will emerge by 2017 or 2018. “We think the right solution is the actinic solution,” Xiong concluded.

Peter Buck of Mentor Graphics, another panelist at the Sept. 18 session, said it was necessary to embrace mask complexity in the years to come. “Directed self-assembly has the same constraints as EUV and DUV (deep-ultraviolet),” he observed.

People in the semiconductor industry place high values on “good,” “fast,” and “cheap,” Buck noted. With the advent of EUV lithography and its accompanying challenges, one of those attributes will have to give way, he said, indicating cheapness was the likely victim.

Mask proximity correction (MPC) and Manhattanization will take on increasing importance, Buck predicted. “MPC methods can satisfy these complexities,” he said.

For all the concern about EUV and the ongoing work with that technology, the panelists looked ahead to the time when electron-beam lithography systems with multiple beams will become the litho workhorses of the future.

Mask-writing times were an issue touched upon by several panelists. Shusuke Yoshitake of NuFlare Technology reported hearing about a photomask design that took 60 hours to write. An extreme example, to be sure, but next-generation multi-beam mask writers will help on that front, he said.

Daniel Chalom of IMS Nanofabrication said that with 20nm chips, the current challenge is reduce mask-writing times to less than 15 hours.

In short, presenters at the SPIE conference were optimistic and positive about facing the many challenges in photomask design, manufacturing, inspection, metrology, and use. They are confident that the technical hurdles can be overcome in time, as they have in the past.

ASML on EUV: Available at 10nm

Wednesday, September 17th, 2014

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By Jeff Dorsch, contributing editor

Extreme-ultraviolet lithography systems will be available to pattern critical layers of semiconductors at the 10-nanometer process node, and EUV will completely take over from 193nm immersion lithography equipment at 7nm, according to Martin van den Brink, president and chief technology officer of ASML Holding.

Giving the keynote presentation Tuesday at the SPIE Photomask Technology conference in Monterey, Calif., Martin offered a lengthy update on his company’s progress with EUV technology.

Sources for the next-generation lithography systems are now able to produce 77 watts of power, and ASML is shooting for 81W by the end of 2014, Martin said.

The power figure is significant since it indicates how many wafers the litho system can process, a key milestone in EUV’s progress toward becoming a volume manufacturing technology. With an 80W power source, ASML’s EUV systems could turn out 800 wafers a day, he noted.

The goal is to get to 1,000 wafers per day. ASML has lately taken to specifying throughput rates in daily production, not wafers per hour, since many wafer fabs are running nearly all the time at present.

ASML’s overarching goal is providing “affordable scaling,” Martin asserted, through what he called “holistic lithography.” This involves both immersion litho scanners and EUV machines, he said.

Martin offered a product roadmap over the next four years, concluding with manufacturing of semiconductors with 7nm features in 2018.

The ASML president acknowledged that the development of EUV has been halting over the years, while asserting that his company has made “major progress” with EUV. He said the EUV program represented “a grinding project, going on for 10 years.”

For all of EUV’s complications and travails, “nothing is impossible,” Martin told a packed auditorium at the Monterey Conference Center.

With many producers of photomasks in attendance at the conference, Martin promised, “We are not planning to make a significant change in mask infrastructure” for EUV. He added, “What you are investing today will be useful next year, and the year after that.”

The Impact Of 14-nm Photomask Uncertainties on Computational Lithography Solutions

Thursday, September 19th, 2013

Computational lithography solutions rely upon accurate process models to faithfully represent the imaging system output for a defined set of process and design inputs. These models, in turn, rely upon the accurate representation of multiple parameters associated with the scanner and the photomask. While certain system input variables, such as scanner numerical aperture, can be empirically tuned to wafer CD data over a small range around the presumed set point, it can be dangerous to do so since CD errors can alias across multiple input variables. Therefore, many input variables for simulation are based upon designed or recipe-requested values or independent measurements. However, certain measurement methodologies, while precise, can be inaccurate. Additionally, there are known errors associated with the representation of certain system parameters. With shrinking total CD control budgets, appropriate accounting for all sources of error becomes more important, and the cumulative consequence of input errors to the computational lithography model can become significant. In this work, we examine with a simulation sensitivity study, the impact of errors in the representation of photomask properties including CD bias, corner rounding, refractive index, thickness, and sidewall angle. The factors that are most critical to be accurately represented in the model are cataloged. CD Bias values are based on state of the art mask manufacturing data and other variables changes are speculated, highlighting the need for improved metrology and awareness.

To download this white paper, click here.