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PCR development for Semiconductor Back-End Processes

Döberl, Josephine LU (2026) EITM01 20261
Department of Electrical and Information Technology
Abstract (Swedish)
This thesis discusses the development of Product Category Rule (PCR) for semiconductor
Back-End (BE) processes. While Life Cycle Assessment (LCA) are common practice in the
industry, there is currently no PCR specifically for BE processes, which creates inconsistent
reporting of emissions. This thesis provides a meta-analysis of allocation methodologies for
semiconductor packaging.
The meta-analysis revealed significant gaps in LCA studies of semiconductor BE pro-
cesses and packaging. In most cases, packaging impact was estimated in relationship to
front-end emissions (varying from 1-33% of total emissions) rather than being independently
modeled. The LCAs on semiconductor packaging showed limited replicability and demon-
strated... (More)
This thesis discusses the development of Product Category Rule (PCR) for semiconductor
Back-End (BE) processes. While Life Cycle Assessment (LCA) are common practice in the
industry, there is currently no PCR specifically for BE processes, which creates inconsistent
reporting of emissions. This thesis provides a meta-analysis of allocation methodologies for
semiconductor packaging.
The meta-analysis revealed significant gaps in LCA studies of semiconductor BE pro-
cesses and packaging. In most cases, packaging impact was estimated in relationship to
front-end emissions (varying from 1-33% of total emissions) rather than being independently
modeled. The LCAs on semiconductor packaging showed limited replicability and demon-
strated misunderstandings of packaging technology, described as an highly unlikely package
configurations of "Flip Chip Wire Bond" packages. The studies used yield-based allocation
with a functional unit of mm3, despite industry recommendations to use wafer count or
area as more appropriate metrics. No literature examined different allocation methods for
semiconductor packaging or their comparative impacts. The most replicable LCA studies
focused on specific processing steps and technologies, using allocation approaches based on
processing steps per tool, cleanroom ratio, and wafer processing time. However, this gran-
ular approach may not be applicable at High-Volume Manufacturing (HVM) scale, where
advanced bottom-up modeling becomes unrealistic due to the large datasets and data points
required. Advanced packaging development is blurring the line between front-end and BE
manufacturing. Techniques such as Redistributive layer (RDL) utilize lithography, making
packaging manufacturing more similar to Front-End (FE) processes. This convergence ex-
pands the scope of technologies that must be covered within PCR for semiconductor BE
processes. A in-house methodology from an Integrated Device Manufacturer (IDM) used a
top down and bottom up approach, and employed different allocation methods depending
on where in the production chain. The raw material was modeled based on macropackage
type together with the BOM, while the other emissions from the back-end production site
the allocation was based on the number of connections on a package (pin). Indirect ma-
terial consumption and waste generation depends on package specific processing steps, the
pin count may not be nuanced to represent the complexity between different packages. This
thesis identifies critical data gaps in current literature for developing PCR for semiconductor
BE processes, with particular focus on allocation methodologies. To advance this field, in-
terviews with HVM facilities and laboratories is essential to understand the data granularity
and develop appropriate allocation methods (Less)
Please use this url to cite or link to this publication:
author
Döberl, Josephine LU
supervisor
organization
course
EITM01 20261
year
type
H2 - Master's Degree (Two Years)
subject
keywords
PCR (Product Category Rule), semiconductor back-end processes, semiconductor packaging, Life Cycle Assessment (LCA), Product Carbon Footprint (PCF), Allocation methodology, pin allocation, Advanced packaging sustainability, carbon footprint reporting
report number
LU/LTH-EIT 2026-1117
language
English
id
9225705
date added to LUP
2026-05-07 11:48:08
date last changed
2026-05-07 11:48:08
@misc{9225705,
  abstract     = {{This thesis discusses the development of Product Category Rule (PCR) for semiconductor
Back-End (BE) processes. While Life Cycle Assessment (LCA) are common practice in the
industry, there is currently no PCR specifically for BE processes, which creates inconsistent
reporting of emissions. This thesis provides a meta-analysis of allocation methodologies for
semiconductor packaging.
The meta-analysis revealed significant gaps in LCA studies of semiconductor BE pro-
cesses and packaging. In most cases, packaging impact was estimated in relationship to
front-end emissions (varying from 1-33% of total emissions) rather than being independently
modeled. The LCAs on semiconductor packaging showed limited replicability and demon-
strated misunderstandings of packaging technology, described as an highly unlikely package
configurations of "Flip Chip Wire Bond" packages. The studies used yield-based allocation
with a functional unit of mm3, despite industry recommendations to use wafer count or
area as more appropriate metrics. No literature examined different allocation methods for
semiconductor packaging or their comparative impacts. The most replicable LCA studies
focused on specific processing steps and technologies, using allocation approaches based on
processing steps per tool, cleanroom ratio, and wafer processing time. However, this gran-
ular approach may not be applicable at High-Volume Manufacturing (HVM) scale, where
advanced bottom-up modeling becomes unrealistic due to the large datasets and data points
required. Advanced packaging development is blurring the line between front-end and BE
manufacturing. Techniques such as Redistributive layer (RDL) utilize lithography, making
packaging manufacturing more similar to Front-End (FE) processes. This convergence ex-
pands the scope of technologies that must be covered within PCR for semiconductor BE
processes. A in-house methodology from an Integrated Device Manufacturer (IDM) used a
top down and bottom up approach, and employed different allocation methods depending
on where in the production chain. The raw material was modeled based on macropackage
type together with the BOM, while the other emissions from the back-end production site
the allocation was based on the number of connections on a package (pin). Indirect ma-
terial consumption and waste generation depends on package specific processing steps, the
pin count may not be nuanced to represent the complexity between different packages. This
thesis identifies critical data gaps in current literature for developing PCR for semiconductor
BE processes, with particular focus on allocation methodologies. To advance this field, in-
terviews with HVM facilities and laboratories is essential to understand the data granularity
and develop appropriate allocation methods}},
  author       = {{Döberl, Josephine}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{PCR development for Semiconductor Back-End Processes}},
  year         = {{2026}},
}