Addressing Killer Defects of Critical Components for Next-Generation High-Volume Manufacturing
By Paul Trio (SEMI); Dalia Vernikovsky (Applied Seals NA)
Big Problems in a Sub-Micron World
As the industry prepares for sub-10nm high-volume manufacturing, there is now a greater sense of awareness that defects introduced by OEM components affect final wafer quality and impact yields and manufacturing costs. For such a major issue affecting the entire semiconductor manufacturing supply chain, there is an even greater urgency for pre-competitive collaboration among key industry stakeholders to take place ─ and it needs to happen now.
SEMI Initiative on Critical Components
To date, there is little industry alignment on how defects are measured on various components and sub-components and on how these results are reported. When yield excursions take place, they often persist too long and resolution is hindered by the fragmentation of the supply chain. The process is rudimentary, which is a bit counterintuitive, given this takes place in a high-technology world. Compounding the situation, while some standards exists, they are often inadequate for advanced process control requirements.
SCIS, Semiconductor Components, Instruments, and Subsystems, is a SEMI Special Interest Group that provides a forum that fosters pre-competitive collaboration and aligns stakeholders on industry-critical issues. Its objectives are to:
- Establish a framework that will enable industry partners to define:
- Measurable defects for different components specific to intended process applications
- Standardized test methods to measure the defects
- Consistent methods for reporting the results
- Implement an industry standard parts traceability process
- Define standardized formats and protocols
- Facilitate communication among suppliers, OEMs, and IDMs.
- Enable efficient problem diagnosis and resolution
Based on SCIS key stakeholder inputs which include components/subcomponents suppliers, major equipment OEMs, device makers, and foundries, working groups were established to focus on various process-critical OEM components:
SCIS Working Groups
Each SCIS Working Group then identified various performance criteria of their components, particularly those that contribute to defects, while also taking into consideration the applicability to various applications and process areas.
Prioritization of Defectivity Parameters
From each identified parameter, the SCIS develops methods for how each characteristic is measured or tested. This approach establishes a baseline on the defect contribution of various components and subcomponents. Test methods are being developed in the following focus areas:
Cleaning & Packaging
Sealing Force Retention
Critical Chamber Components
RF Generator Transient Response
RF Power Delivery System
Traceability Verification Model
Table 1 Focus Areas of SCIS Working Groups
Some SCIS teams presented their preliminary test methods at the last SCIS face-to-face meeting in conjunction with SEMI ASMC conference in May 2016. Additional test methods are expected to be completed in time for the SCIS meeting (July 14) at SEMICON West 2016.
Metallic and Hydrocarbon Contamination in Gas Delivery Systems
The SCIS Gas Delivery Group is focusing on metallic and hydrocarbon contamination in defining a standard method of evaluating wetted surface material composition of UHP gas delivery components and plumbing. Led by Matt Milburn (Ultra Clean Technology, UCT) and Troy Freeman (Horiba), the team presented their preliminary test methods at the ASMC meeting. Their proposed specification details the method to extract and measure metallic elements present on the wetted surfaces. The group has also developed a method for hydrocarbon compounds. Their aim was for these test methods to employ out-of-box and as-built components and systems thereby making this approach more widely accessible.
Preliminary Test Method for Metallic Contamination in Gas Delivery Systems (excerpt)
“The expected benefit from the test methods being developed is for suppliers and users to be able to reference a common test method and evaluation language,” said Matt Milburn, principal engineer at UCT. “This will allow all parties involved to focus on results and paths to improvement.”
RF Transient Response and Power Delivery Systems
The SCIS RF Group is focusing on transient response on RF generators as well as RF power delivery systems. While several SEMI RF Standards already provide solid foundation for RF products and systems, these test methods need to be updated to align with the latest industry requirements. For example, the SCIS RF Group has developed a revision proposal for SEMI E135 (Test Method for RF Generators to Determine Transient Response) to address dynamic load conditions to the RF generator.
SEMI E135 was developed to define a standardized test method for measuring the transient response of RF generators used in semiconductor processing equipment. The existing version’s scope is limited to testing the RF generator into a nominal 50Ω load. This represents a static load condition.
Semiconductor processing equipment provides a dynamic load condition to the RF generator. An additional test to determine the transient response must incorporate a simulated a worst case condition. The addition of two load conditions is proposed.
Incorporating Current Industry Requirements on RF Generator Transient Response
The RF Group will also address transient conditions for RF power delivery systems by proposing revisions to the SEMI E113 Standard (Specification for Semiconductor Processing Equipment RF Power Delivery Systems).
SEMI E113 aims to provide RF power delivery specifications for semiconductor processing equipment that leads to improved system and subsystem performance. It outlines performance criteria as well as required documentation that must be supplied with the system or subsystem components. The goal of the Document is to provide the specifications needed to produce a well-characterized RF power delivery system, where stability, repeatability, and important electrical parameters such as delivered power, current/voltage, and the impedance of the system can be determined within the operating space.
Semiconductor processing equipment provides a dynamic load condition to the matching network in a RF delivery system. SEMI E113 does not address transient conditions while the standard of 80% into nominal condition may not be sufficient. The standard should define the phase angles to be tested and the minimum of test points to be used. Finally, a test data table should be created to collect and record the data.
Seal Cleaning & Packaging and Sealing Force Retention
The SCIS Seals Group had previously completed its work on total organic testing (TOC), surface extractable metal contamination, and ash metal analysis which resulted in the major revision to the SEMI F51 Standard (Guide for Elastometric Sealing Technology). These changes came into effect in the November 2015 publication of SEMI F51.
The Seals Group has since shifted its focus on cleaning, packaging, and handling. While process controls are established to ensure dimensional accuracy and specification, there is no industry standard on how seals are cleaned, packaged, and handled after they are manufactured. The lack of industry alignment on these final production steps often results in contaminants being introduced into the wafer manufacturing process.
The proposal will also include considerations for handling, labelling, and storage conditions for perfluoro-elastomeric seals. There is currently no industry alignment on seal information provided in the packaging labels as well as which bag (e.g., inner vs outer bag) certain label information should be placed. Seal product information such as material, dimensions, as well as production/cure date and purchase order information are usually provided in these labels. However, there are also considerations for including storage conditions (e.g., cool, dry, no UV environment) and expiration/discard by dates to ensure seal performance once they are on customer sites. Finally, the proposal will include recommended measurement methods for seal cleanliness during handling and packaging. With engagement from Applied Seals NA; Greene, Tweed; DuPont; and Valqua, the group will present their work at the SCIS meeting at SEMICON West 2016.
Guidance on Seal Cleaning, Handling, and Packaging Developed by SCIS Seals Group
The SCIS Seals Group also plans to develop test methods for sealing force retention. Such standards for the semiconductor industry is lacking so the group is looking into related documents in the aerospace industry to determine whether certain provisions can be adopted.
Parts Traceability Model Aims to Improve Yield Excursion Process
SCIS is addressing the need for improved component parts traceability that will enable effective problem diagnosis and faster resolution through the Traceability Verification Group. The group is developing an implementation model that ensures Key Characteristics are controlled with compliance information easily accessed via a cloud based application. Intellectual property is secured via pre-approved access levels. The model holds all suppliers accountable but also ensures proprietary information is not compromised.
Traceability Verification Information Exchange Model
SEMI SCIS to SEMI Standards
Similar to the F51 revision initiative, the resulting preliminary testing and implementation methods developed by the various SCIS groups will eventually feed into the SEMI Standards Program. The transition of completed SCIS work is expected to occur as early as the North America Standards Fall 2016 meetings. Ultimately, the SCIS framework as well as the resulting SEMI Standards will help the industry achieve the desired contamination levels or parts performance required in advanced process nodes.
Critical Industry Initiative
Addressing the challenges of next-generation high-volume manufacturing will require joint efforts among industry stakeholders. While SCIS represents component and sub-component manufacturers, it is essential having equipment OEMs as well as device makers and foundries be a part of dialogue since this issue affects the entire supply chain and ecosystem.
“Everyone talks about collaboration – one of the most overused and underutilized words in this industry – indeed, the actual actions, the results of those entities that actually interact and bring about the paradigm shift – those positive actions are born of strong will and passion and openness and a desire to help create change,” said Dalia Vernikovsky, Applied Seals North America and SCIS co-chair. She points out, “Those people will actually achieve the true intent of the word and ultimately, improve the industry and the impact that collaboration is intended to personify.”
Engaging in these SEMI SCIS initiatives provides a very strong value proposition for IDM-OEM-suppliers alike.
SCIS Value Proposition
The SEMI SCIS Special Interest Group is open to all SEMI Members. There will be an SCIS face-to-face meeting in conjunction with the SEMICON West 2016 (July 14). West attendees are welcome to join this face-to-face meeting. After SEMICON West, SCIS will reconvene in September immediately following the SEMI Strategic Materials Conference (SMC). The SCIS meeting will be held at SEMI Headquarters. SCIS groups will meet regularly via teleconference in between face-to-face meetings. For more information or to join the SCIS SIG, please contact Paul Trio at SEMI (firstname.lastname@example.org).