Retained-chlorine amorphous aluminum oxychloride ALD film for copper-barrier and packaging dielectric applications

Advanced semiconductor packaging is in the middle of a materials transition forced by physics, not preference. As die-stacking density climbs through HBM4 and chiplet interposer architectures, the interconnect stack must accommodate tighter line/space rules, thinner dielectric layers, and copper redistribution lines (RDL) that cannot tolerate even trace metal diffusion. Glass-through-via (TGV) substrates are displacing traditional organic laminates precisely because glass offers superior dimensional stability and lower loss at high frequency — but glass creates a new set of materials challenges: the via sidewall must be conformally coated with a film that simultaneously blocks copper diffusion, survives thermal cycling across a wide CTE mismatch, and does not introduce parasitic capacitance that defeats the dielectric advantage of glass. No single incumbent material does all three simultaneously with the conformality that atomic layer deposition (ALD) uniquely provides. This asset, drawn from the catalysts and energy-conversion materials portfolio, targets that intersection. It covers a process-defined amorphous aluminum oxychloride film — deposited by ALD from trimethylaluminum (TMA), hydrogen chloride, and water or ozone — in which chlorine is intentionally retained within the amorphous alumina network at concentrations of 2–15 atomic percent (preferably 4–8 at%). That retained chlorine is not a contamination artifact; it is a deliberate structural dopant that modulates the film's dielectric constant, dielectric breakdown field, coefficient of thermal expansion behavior, and copper-blocking effectiveness relative to conventional ALD Al2O3. The asset positions the retained-chlorine amorphous Al-Cl-O film as a drop-in ALD step for TGV barrier liners, interposer dielectrics, RDL interlayers, and radiation-hardened packaging layers — all addressable from a single ALD tool flow modification. The timing is material: glass interposer adoption is accelerating, TGV qualification cycles are underway at multiple OSATs, and the window to establish prior art and process IP in this specific chemistry is narrowing.

The material is an amorphous aluminum oxychloride, designated AlOxCly, produced by modifying a standard TMA-based ALD cycle to incorporate HCl pulses alongside the water or ozone oxidant. In conventional ALD Al2O3, the Cl introduced with TMA is fully displaced during the oxidant half-cycle, yielding stoichiometric alumina. In this process, the HCl pulse timing, partial pressure, and cycle sequencing are tuned so that a defined fraction of Al-Cl bonds are preserved through the oxidant step and incorporated as structural chlorine within the amorphous network. The resulting film is X-ray amorphous — no crystalline phases are present by XRD — and contains 2–15 at% Cl, with the preferred operating window of 4–8 at% representing the range where dielectric and barrier properties appear most favorable while film density and conformality are preserved. Film thickness is tunable across 5–500 nm, covering both ultra-thin barrier applications and thicker dielectric interlayer applications from the same process family. Retained chlorine in an amorphous alumina network performs several functions simultaneously. It suppresses crystallization relative to pure Al2O3 (which tends to crystallize toward gamma-Al2O3 at packaging-relevant thermal budgets), preserving the conformal amorphous morphology required for uniform step coverage in high-aspect-ratio TGV structures. The Cl occupancy of tetrahedral and octahedral Al coordination sites disrupts the periodic lattice formation, stabilizing the amorphous phase. Chlorine's electronegativity and polarizability also modulate the dielectric constant of the film relative to crystalline alumina, offering the potential to tune the effective-k value of the barrier/dielectric layer — a meaningful advantage in RDL interlayer applications where every tenth of a unit reduction in k directly reduces RC delay. The film's thermal expansion behavior is similarly influenced by the network modifier role of Cl, which affects the density and cross-linking of the Al-O-Al backbone. Copper diffusion blocking in amorphous alumina is well-established; the key differentiator here is that retained chlorine strengthens the grain-boundary-free barrier character of the amorphous network while simultaneously providing the dielectric modulation described above — a combination not accessible from crystalline Al2O3 or from conventional TaN/TiN physical-vapor-deposition barriers. TaN and TiN require line-of-sight deposition geometries that struggle with TGV aspect ratios above approximately 5:1, while ALD-based processes coat conformally regardless of geometry. The asset's claim of radiation hardness adds a secondary market dimension: amorphous metal-oxide dielectrics are known to be more tolerant of displacement damage than crystalline counterparts because there is no ordered lattice to disorder, and a chlorine-stabilized amorphous phase would be expected to maintain that advantage through radiation dose levels relevant to space and defense packaging. The computational work supporting this asset is targeted rather than exhaustive, reflecting the process-defined nature of the invention — the film is defined by the ALD process rather than by a single crystal structure, so standard crystal-structure-based stability screening is not directly applicable. MatterSim molecular-dynamics simulations were run on retained-Cl amorphous Al-O-Cl structural models across at least 18 output configurations, providing atomistic evidence that Cl atoms remain incorporated within the amorphous network under thermal conditions relevant to ALD deposition and post-deposition annealing. A ShakeNBreak configurational screen was performed to sample the amorphous configuration space and confirm that retained-Cl configurations are not high-energy outliers. Density-functional perturbation theory (DFPT) calculations were run on crystalline approximants of the Al-Cl-O composition to establish a bounding estimate of the dielectric tensor, grounding the claimed dielectric-modulation benefit in first-principles electrostatics even though the experimental film is amorphous. Together these simulations provide a physically consistent picture of why retained chlorine stabilizes the amorphous phase and what direction dielectric properties shift — without overclaiming quantitative precision for a material whose exact short-range order depends on process conditions.

The addressable market for this asset spans advanced semiconductor packaging, specifically the sub-segments where conformal dielectric/barrier deposition in high-aspect-ratio structures is a technical bottleneck. Glass-through-via substrates represent the most immediate and differentiated opportunity: the glass interposer market is projected to scale from a nascent specialty segment into a multi-billion-dollar infrastructure layer for HBM4 and high-performance compute packaging over the next four to six years, with TGV liner materials representing a recurring consumable cost embedded in each substrate panel. Estimates for the overall advanced packaging dielectric and barrier materials segment fall in the $1–3 billion range — stated as an estimate, not a precision figure — with ALD-deposited films capturing an increasing share as aspect ratios make PVD less viable. This is not a winner-take-all commodity market; it is a qualified-materials market where a single process qualification at one OSAT or glass-substrate vendor can generate sustained royalty or licensing revenue tied to wafer or panel throughput. The customer base is concentrated and technically sophisticated: outsourced semiconductor assembly and test providers (OSATs) operating advanced packaging lines, glass-core substrate vendors qualifying TGV processes, and ALD tool OEMs whose tool flows would incorporate the process. The licensing logic is straightforward — a royalty per wafer or panel incorporating the Al-Cl-O ALD step, or a process license tied to the specific TMA/HCl/oxidant cycle chemistry. Secondary market segments with licensing potential include radiation-hardened packaging for space and defense applications, where the amorphous, grain-boundary-free character of the film is an inherent reliability advantage and where qualification cycles favor established chemistry families (alumina-based materials are already DoD-familiar) over novel barrier approaches. The intersection of conformal ALD, copper-diffusion blocking, and dielectric tunability in a single process step creates genuine value-per-unit economics that justify licensing conversations with multiple customer types simultaneously.

lower-k + Cu-barrier + amorphous conformality vs dense crystalline alumina

amorphous + retained-Cl + ALD process; crystalline AlClO/Al2O3 + broadly-claimed crystalline Al2O3 ALD excluded

The most strategically aligned acquirers or licensees for this asset are ALD tool and precursor companies (Applied Materials, Lam Research, ASM International, Entegris/CMC Materials) that supply the process infrastructure for advanced packaging lines and would benefit from owning the process chemistry IP that differentiates their tool flows for TGV applications. A process license embedded in a tool-qualification package — where the tool vendor sublicenses the retained-Cl ALD step to OSAT customers as part of a qualified recipe — is a natural commercial structure. Glass-core substrate vendors such as AGC, Corning, and Nippon Electric Glass, which are qualifying TGV processes for HBM4 interposer supply chains, represent a second category of strategic licensee with direct panel-throughput exposure. Large OSATs with captive advanced-packaging capability — ASE, Amkor, JCET — are a third category, particularly as they internalize dielectric-layer process steps rather than sourcing finished substrates. For the radiation-hardened packaging segment, defense and space prime contractors and their supply chains (Northrop Grumman, Raytheon, L3Harris, and their packaging subcontractors) represent buyers who operate in a market where switching costs are high, qualification cycles are long, and a material that combines conformal ALD deposition with proven amorphous rad-hard character commands a premium. The asset's dual commercial character — mainstream advanced packaging in volume, rad-hard packaging in value — makes it attractive both as a standalone process license and as a complementary addition to a broader advanced-materials or packaging IP portfolio acquisition.

The primary technical risk is the status of the two open experimental validation gates. Until XPS or RBS confirms that chlorine is genuinely incorporated as bound Al-Cl within the amorphous network (rather than physisorbed surface chloride that could desorb during post-deposition processing), the retained-Cl claim rests on process design intent and MD simulation rather than direct chemical characterization. Similarly, the copper-barrier performance relative to TaN/TiN baselines is unvalidated by thermal-aging coupons, which means the competitive displacement argument is currently mechanistic rather than data-backed. A buyer acquiring this asset should budget for a modest experimental program — standard thin-film deposition and analytical characterization — to close both gates before committing to OSAT qualification discussions. The process is not exotic: TMA-based ALD is commodity infrastructure at any advanced packaging fab, and HCl is a standard gas-panel chemical, so coupon fabrication does not require specialized facilities. A secondary risk is the relatively narrow preferred Cl range (4–8 at%). If process integration studies reveal that the optimal Cl content for a given application (dielectric versus barrier versus rad-hard) shifts outside this window, the specification may need broadening, which is manageable at the prosecution stage but adds timeline. Competitive risk from crystalline-Al2O3 ALD incumbents is bounded by the negative limitations — this family does not claim that space — but if TaN ALD processes mature rapidly and solve the conformality problem in TGV at competitive cost, the copper-barrier differentiation of the retained-Cl film would need to rest more heavily on the dielectric-k modulation and amorphous-phase arguments. The roadmap to de-risk is clear and inexpensive relative to the potential market: close the two experimental gates, run a process window study across the 2–15 at% Cl range, and initiate a qualification conversation with one glass-substrate vendor or OSAT to anchor the first commercial reference.