OPC+ Cloud Platform

What Is Optical Proximity Correction (OPC)?

Semiconductor and photonic devices are fabricated by projecting light through a patterned mask onto a photosensitive wafer—a process called photolithography [1]. Because the wavelength of the exposure source is comparable to, or larger than, the minimum feature sizes being printed, optical diffraction causes the projected image to deviate systematically from the intended design: line ends shorten, corners round off, and isolated features may fail to print entirely.

Optical Proximity Correction (OPC) is the pre-distortion technique applied to the mask layout to compensate for these optical and process-induced effects, so that the final printed pattern on the wafer faithfully reproduces the designer's intent. Modern OPC is increasingly realized through Inverse Lithography Technology (ILT)—a full-mask optimization approach that directly solves for the mask shape required to produce a target wafer image [2].

Figure 1. The target layout (left, without correction) produces a blurred wafer image due to diffraction. The OPC-corrected mask (right) pre-distorts the design so the printed result faithfully reproduces the intended pattern.

Why Is Traditional OPC Insufficient?

Conventional OPC tools rely on CPU-based, rule-driven solvers designed for Manhattan geometries (rectilinear, axis-aligned shapes). They present three fundamental limitations as the industry advances toward photonics and curvilinear CMOS nodes:

SEM Validation on Fabricated Devices

The following Scanning Electron Microscope (SEM) images present fabricated device results demonstrating the direct, measurable impact of OPC correction on real photonic structures. All results were obtained from wafers processed at collaborating fabrication facilities.

Line Pattern — Line End Shortening

Without OPC correction, diffraction at the tips of line features causes the printed ends to recede inward, resulting in lines that are shorter than the target design. This line end shortening effect introduces critical dimension (CD) error along the line length axis. OPC pre-compensation extends the mask geometry at line ends so that the fabricated result matches the intended length.

Without OPC

Line end shortening visible; printed length undershoots target geometry

With OPC

Line ends accurately reproduced; CD along length axis restored

Figure 2. SEM images of fabricated line patterns. Scale bar: 5 µm.

Ring Resonator — Critical Defect Elimination

For photonic ring resonators, OPC correction is critical to device functionality. Without correction, the coupling gap region fails to open properly—a fatal fabrication defect that renders the device non-functional optically. With OPC, the waveguide geometry is accurately reproduced and the coupling region is fully resolved [5].

Without OPC

Critical defect: lower photoresist layer not opened (circled in red)

With OPC

Clean fabrication: coupling region fully resolved, device functional

Figure 3. SEM images of fabricated ring resonators. Scale bar: 5 µm (overview), 1 µm (inset).

Metalens — Sub-Wavelength Feature Survival

Metalenses rely on densely packed sub-wavelength nano-structures whose precise geometry determines the phase profile of the device. Without OPC, the photolithography process fails to resolve the smallest features—they are either significantly distorted or lost entirely—compromising the optical function of the device. With OPC, all features are faithfully reproduced after lithography, preserving the intended phase distribution across the aperture [5].

Without OPC

Small features fail to resolve; critical nano-structures lost or severely distorted after lithography

With OPC

All sub-wavelength features fully resolved; phase profile of metalens preserved

Figure 4. SEM images of fabricated metalens structures. OPC ensures survival of all sub-wavelength features critical to device phase control.

Complete Correction Workflow

OPC+ integrates three essential modules into a unified, automated pipeline. Each module can be configured independently or combined to match the requirements of a specific fabrication process.

How to Use OPC+ Cloud Platform

Prerequisites

• Target layout file in GDS or OASIS format
• Scanner parameters (exposure wavelength, numerical aperture, illumination configuration)
• (Optional) CD-SEM calibration data for physical model fitting

Step-by-Step

1. Access the Platform
   Navigate to https://opc-cloud.com/ and register an account. The platform supports both English and Traditional Chinese interfaces.
   

   Figure 5. OPC+ web portal login page. Language can be toggled from the top-right menu.

2. Upload Your Design
   Upload your target layout file (GDS/OASIS) and enter the scanner parameters for your fabrication process.
3. Configure Calibration (Optional)
   Upload CD-SEM measurement data if physical model calibration is required for your specific fabrication environment.
4. Submit and Monitor
   Submit your job to the GPU cluster. Track processing progress in real time through the web dashboard.
5. Download Results
   Retrieve the corrected mask layout (GDS/OASIS), ready for mask writing and manufacturing.

Flexible Deployment Models

OPC+ offers three deployment configurations to accommodate varying security, performance, and budgetary requirements.

Demo & Access

Get in Touch

Interested in accessing the OPC+ Cloud Platform or exploring research collaboration? Contact the team below.