2.5D/3D Process Development Engineer

Company: Celestial AI
Location: Santa Clara
Posted on: February 14, 2026

Job Description:

Job Description Job Description About Celestial AI As Generative AI continues to advance, the performance drivers for data center infrastructure are shifting from systems-on-chip (SOCs) to systems of chips. In the era of Accelerated Computing, data center bottlenecks are no longer limited to compute performance, but rather the system's interconnect bandwidth, memory bandwidth, and memory capacity. Celestial AI's Photonic Fabric™ is the next-generation interconnect technology that delivers a tenfold increase in performance and energy efficiency compared to competing solutions. The Photonic Fabric™ is available to our customers in multiple technology offerings, including optical interface chiplets, optical interposers, and Optical Multi-chip Interconnect Bridges (OMIB). This allows customers to easily incorporate high bandwidth, low power, and low latency optical interfaces into their AI accelerators and GPUs. The technology is fully compatible with both protocol and physical layers, including standard 2.5D packaging processes. This seamless integration enables XPUs to utilize optical interconnects for both compute-to-compute and compute-to-memory fabrics, achieving bandwidths in the tens of terabits per second with nanosecond latencies. This innovation empowers hyperscalers to enhance the efficiency and cost-effectiveness of AI processing by optimizing the XPUs required for training and inference, while significantly reducing the TCO2 impact. To bolster customer collaborations, Celestial AI is developing a Photonic Fabric ecosystem consisting of tier-1 partnerships that include custom silicon/ASIC design, system integrators, HBM memory, assembly, and packaging suppliers. ABOUT THE ROLE In this role you will utilize your in-depth process engineering and partner management experience to drive company's AI products from concept to high volume manufacturing. You will be responsible for managing and driving the assembly process technology development in close collaboration with foundries and OSATs to ensure design for manufacturing, reliability, and cost. Responsibilities will include identification and mitigation of risk to new technologies used in product integration and ensure factory readiness through maturing product during the NPI phase. This job will require you to have hands-on experience in wafer process development, working with consumable suppliers, 2.5D/3D CoW assembly development along with strong project management, written and verbal communication skills. Also required for the job is a can-do attitude to prioritize and address issues with a high sense of urgency. ESSENTIAL DUTIES AND RESPONSIBILITIES Work with cross-functional packaging teams and lead process development at foundry along with 2.5D/3D CoW process development with particular emphasis on chemistry development with packaging consumable suppliers at OSATs to bring packaging solutions from concept to prototypes and ramp to high volume manufacturing with aggressive cost reduction strategies Actively manage qualification of packages with sensitivity to physics of failures for high thermo-mechanical reliability, while operating within established cost constraints Manage internal and external resources effectively and efficiently towards established corporate milestones Drive ideation and innovation of advanced package solutions and specifications with vendors to advance productization efforts by Celestial AI QUALIFICATIONS 10 years of experience in Semiconductor Packaging, Process and Technology Development Expert level understanding of advanced foundry process node and its interaction with Packaging/assembly/substrate across various package technologies is required Expertise in advanced packaging technologies: knowledge and insight to deliver high density/high performance interconnects with TSVs in various 2.5D/3D package form factors Proven track record of bringing products from Technology development, package design/definition, qualification, NPI through HVM is required Working level understanding of cross-functional packaging areas: package architecture, design rules, BOM, enabling material/process technologies, mechanical, design for manufacturing, reliability, and cost Familiarity with component & system level reliability, testing, and FA Experience with photonics packaging will be preferred but is not necessary Experience in project management and communicating technical and project/program status and issue resolution at the executive level Excellent problem-solving skills with strong fundamentals in science, sound engineering judgment, and analytical ability Effective communicator and comfortable engaging with internal cross functional teams as well as domestic and overseas suppliers Excellent attention to detail, process and operationally oriented and self-driven with the ability to work independently and take projects to completion with minimum supervision M.S or Ph.D. in Chemical Engineering, Materials Science, Mechanical Engineering, Chemistry or Physics is required LOCATION : Santa Clara, CA For California Location: As an early stage start up, we offer an extremely attractive total compensation package inclusive of competitive base salary, bonus and a generous grant of our valuable early-stage equity. The target base salary for this role is approximately $195,000.00 - $235,000.00. The base salary offered may be slightly higher or lower than the target base salary, based on the final scope as determined by the depth of the experience and skills demonstrated by candidate in the interviews. We offer great benefits (health, vision, dental and life insurance), collaborative and continuous learning work environment, where you will get a chance to work with smart and dedicated people engaged in developing the next generation architecture for high performance computing. Celestial AI Inc. is proud to be an equal opportunity workplace and is an affirmative action employer. LI-Onsite

Keywords: Celestial AI, Vallejo , 2.5D/3D Process Development Engineer, Engineering , Santa Clara, California