Page 36 - Chip Scale Review_November December_2022-digital

Large-panel fan-out perspective on cost, yield,

and capability

By Clifford Sandstrom, Robin Davis, Benedict San Jose [Deca Technologies, Inc.]

W i t h s u pp l y c ha i n panel format will be described, including panel format can fit 256 devices per panel,

shortages for many of
mask-less laser direct imaging (LDI). Our
the traditional packaging scaling to 2µm lines and spaces using given the same 36mm x 36mm package area.
This results in a format efficiency of 92%
technologies, the semiconductor industry patterning technology, a critical part of the (see Figure 2b). The square panel format’s
is looking for alternative solutions. One of process, provides precise real-time design nearly 20% higher utilization of molded area
the key technologies under consideration and alignment. This is critical in a multi- translates directly to lower cost.
by many is molded fan-out panel-level die environment—providing the ability to Figure 3a details the most highly utilized
packaging (FOPLP). This technology is implement high-density interconnects in a materials in the process for M-Series 300mm
particularly appealing as it offers a high- large-panel format. round wafer, shown as a percentage of
density, high-throughput solution and can the total material cost. The polyimide and
achieve comparable, or better, end results Cost considerations laminated films such as carrier laminate,
as compared to conventional laminate or To better explain the cost advantage of temporary backside laminate (BSL) used for
lead frame-based packages. using a 600mm square large panel compared warpage control, and photo dry film (DFR)
Currently running at volumes in the to the conventional 300mm round wafer, represent more than 30% of the total bill of
millions of units per day on a 300mm an analysis of utilization and effective area materials (BOM) cost. Consumption of these
round format, Deca’s M-Series™ fan-out is outlined using a concept called format materials is directly proportional to the panel
®
PLP technology and Adaptive Patterning efficiency. To compute for the format format efficiency described earlier. These
have been scaled up to the new industry efficiency of a fan-out molded panel, the total materials correspond to potential cost savings
standard 600mm x 600mm large-panel usable package area is divided by the format in a 600mm large-panel format by reducing
format for production. The first 600mm area. For example, let’s consider a 9-die material wastage.
production implementation in nepes chiplet fan-out device with an overall package An example of cost-saving opportunities
laweh in Cheongan, South Korea, began size of 36mm x 36mm molded in a 300mm described above includes the following: using
operations in 2021 and continues to ramp round wafer. The 300mm wafer format slot or slit coating is ideal for a square panel
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in production. The SEMI standard 600mm (70,686mm ) can fit 40 packages per wafer where just 22ml of polyimide is required for
square format provides a 500% increase (a total usable package area of 51,840mm ) a dielectric layer vs. the 8ml volume typically
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in usable area per panel vs. 300mm round, resulting in a format efficiency at 73% (see used in spin coating on 300mm wafers. This
providing cost-effective capacity growth Figure 2a). In contrast, a 600mm large- translates to a 44% reduction in volume
as well as a powerful platform for high-
density integration of multi-die and chiplets
in 2D, 2.5D, and 3D structures.
The 600mm square format was created
with considerations for both short-term
implementation and long-term optimized
productivity. The ability to segment the
600mm panels into four 300mm square
sub-panels for use with conventional
300mm round wafer probe test equipment
was a driving factor for the short term
(Figure 1). Extending process capability
for key lithography, metal deposition,
and other processes to complete the
600mm panel provided a challenging, yet
achievable target for equipment suppliers.
Focusing on economies of scale, the
300mm round baseline is examined as
compared to various large-panel formats.
Implementation strategies of the industry’s
first high-volume chips-first, chips-up
M-Series fan-out structure in a large- Figure 1: M-Series 300mm round and 600mm square panel.

34 Chip Scale Review November • December • 2022 [ChipScaleReview.com]
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