Duffin

1NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

DFEHSDesign for Environment, Health, and Safety

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Material contributions by Bob Duffin,

Motorola Corp.

1999 Arizona Board of Regents for The University of Arizona

Duffin

2NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

What is DFEHS?

• Systematic approach to design, manufacture, use, and disposition of products and processes that incorporates consideration for EHS impacts

• Management approach for evaluating and mitigating EHS concerns at the earliest possible stages of product/process design

• Optimization of balance between EHS priorities and design quality factors (cost, yield, performance, etc.)

• Ongoing evaluation and continuous improvement

Duffin

3NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Driving Forces

• Decreasing cost

– reduced material consumption, cycle time, regulatory resources, delays, etc.

– reduced operating costs

– reduced hazardous materials handling costs• storage, training, site response, compliance req’s, disposal, etc.

• Achieving sustainability for tools/processes

– ensures that EHS issues will not be the cause of tool/process phase out

Duffin

4NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Driving Forces (cont’d)• Minimizing time to market

– avoids cost delays at implementation stage of projects• permit modifications, EHS review, retrofits, etc.

– anticipates potential problems with regulatory issues

• Maintaining market share– ensures compliance issues for international standards (ISO, EMAS,

etc.) are addressed

• Increasing market share– competitive tool in the marketplace– customer/consumer impression of “greenness” matters

Duffin

5NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Driving Forces (cont’d)

• Reducing corporate risk factors

– elimination of liability related to haz-waste management

– early identification of required permit modifications

• Projecting environmental leadership

– business values

Duffin

6NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Hot EHS Issues - Semiconductor Industry

• Global Warming

– 1995: IPCC declared the presence of a human influence on global climate

– GW gases used by the semiconductor industry: PFC’s• CF4, C2F6, SF6, NF3, C3F8, CHF3

• utilized during plasma cleaning, etching

– Push to develop CVD and etch process that eliminate or reclaim PFC emissions

Duffin

7NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Hot EHS Issues - Semiconductor Industry (cont’d)

• Water Use Reduction

– Estimated 10,000 gal DI water per day per one 200 mm wafer through entire process

– Ion exchange for DI production - large user of bulk chemicals = significant waste

– Water use can limit new factory location and production volume

• Worker Safety

– Recordables, lost day cases, worker’s comp cases, etc.

Duffin

8NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Levels of Analysis

• Device design and process development

– Individual process steps

– In-house new tools and existing tool optimization

– Agreements with suppliers concerning tool design

– Equipment specifications

– Entire tool set and process flow

• Manufacturing

– Facilities integration

– Ergonomics

Duffin

9NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Case StudiesMotorola Corp.

• Segregated Ammonia Exhaust System Problem - Ammonia exhaust routed to acid exhaust system created problems with visible

plumes and scrubber effluent testing due to ammonia salt formation (result of ammonia mixing with acid gases)

Solution - Retrofit fabs with segregated ammonia exhaust scrubbers– Retrofit cost = $3-5 million– New fab construction cost = $1-2 million

• Water Reuse Problem - Many wet cleans tools that utilize water are supplied with the proper plumbing

to recycle the spent water. However, most fabs are not equipped with the plumbing network to support water recycle.

Solution - Retrofit with very low payback– Retrofit cost = $4.8-6 million– Cost to hook up each wet bench to recycle plumbing - $7500

Duffin

10NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Case Studies (cont’d)Motorola Corp.

• Methanol to IPA Conversion Problem - Methanol, which is considered a hazardous air pollutant (HAP), is used as a

solvent in metal etch deveil and photoresist stripping operations. Ineffective abatement with current VOC equipment means that the site could be subject to a Title V permitting program, which would significantly decrease permit flexibility and increase downtime spent on permit modification.

Solution - Convert processes to use IPA, which is not considered a HAP– Saves $300,000 in permitting costs– Avoids the need for $1-2 million in specific abatement equipment for the

methanol

• Water-Based Photoresist Stripping– The switch from a solvent-based stripper system to a water-based system resulted

in annual savings of $70,000, due to cheaper chemicals and reduction in waste treatment steps. In addition, the Thin Film process became easier to control.

Duffin

11NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Case Studies (cont’d)Motorola Corp.

• Tool Exhaust– A new tool for wafer cleans was set to be installed in place of an old

system. It utilizes HF vapor instead of wet chemistry, followed by an IPA dry. The current plumbing was hooked to solvent exhaust, and HF vapor was not used in the fab prior to the introduction of this new tool. The start up was delayed while ducting modifications were made to plumb the new tool effluent to the acid exhaust system.

• Pump Oil Reclaim– A system designed to reclaim synthetic oil in vacuum pumps saved over

$220,000 during the first two years of use. It consists of rough and fine filters to remove acids and other impurities. The cost of new oil is $170-179 per quart, while the cost of reclaimed oil is only $0.62 per quart.

Duffin

12NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Consequences of No DFEHS

• Morass of regulatory issues

– example: air permit process = 18 months in AZ

• Possible non-compliance with new and ever-changing regulations

– 1983 avg. RCRA violation fine = $8,640, 1989 avg. avg. RCRA violation fine = $103k, ….

• Criminal liability for employees and community

• High cost of haz-waste cleanups

Duffin

13NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Trends

• Global acceptance of DFEHS

• Increased legislation

• Internal design aids

– Company policies

– Matrices/questions to answer

– Flowcharts

• Software tools

– Example = Computerized Assessment of Relative Risk Impacts (CARRI)

Duffin

14NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

What can engineers do?

• Reduce:

– energy and water use, chemicals, etc. in support of conservation of natural resources

– pollution at the source whenever possible

– the toxicity of chemicals used

– employee exposure to chemicals

– the use of chemicals by optimizing processes

Duffin

15NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

What can engineers do? (cont’d)

• Reuse:

– previous designs and processes which minimize impact on the environment

– shipping packaging

• Recycle:

– waste or by-products generated wherever pollution can not be reduced to zero at the source

– purchase recycled products wherever possible