Dynamic In-Situ Process Control

Reactive PVD processes are inherently sensitive. Small drifts in gas flow, target condition, or chamber pressure can shift a film’s stoichiometry, reduce deposition rate, or push a process into an unstable operating regime, often without any visible warning.

Dynamic in-situ process control is the answer: real-time, closed-loop monitoring that continuously reads process conditions and corrects them before the film goes out of spec.

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PEM and RGA

Polyteknik integrates two complementary in-situ monitoring technologies – plasma emission monitoring (PEM) and residual gas analysis (RGA) – directly into our deposition system control software, giving operators fast, precise, and fully automated control over reactive thin film processes.

What PEM delivers

Stable stoichiometry in oxide and nitride films
High deposition rates comparable to metallic mode sputtering
Prevention of target poisoning
Fast dynamic response — corrections happen in milliseconds
Consistent, repeatable results across production runs

The reactive sputtering control challenge

In reactive sputtering, a metal target is sputtered in the presence of a reactive gas – typically oxygen or nitrogen – to deposit compound films such as oxides or nitrides.

The process operates in a narrow transition zone between two very different states: metallic mode, where the target surface remains clean and deposition rates are high, and poisoned mode, where the reactive gas overwhelms the target surface, drastically reducing the deposition rate and altering film properties.

This transition is non-linear and can happen rapidly. Without active control, the process drifts, stoichiometry becomes inconsistent, and repeatable film production becomes difficult.

How PEM works

Plasma emission monitoring solves this by reading the optical emission spectrum of the sputtering plasma in real time. Every element present in the plasma emits light at characteristic wavelengths.

By tracking the intensity of a specific emission line – typically from the metal or the reactive gas – the PEM system obtains a continuous, millisecond-speed signal that reflects the actual state of the reactive process.

This signal feeds directly into the Polyteknik control software, which adjusts the reactive gas flow to maintain a precise setpoint.

The result is a stable, closed-loop control system that holds the process in the optimal transition region, delivering high deposition rates while ensuring correct and repeatable film stoichiometry.

Residual Gas Analysis (RGA)

What is an RGA?

A residual gas analyzer is a compact mass spectrometer mounted directly on the vacuum chamber. It measures the partial pressures of individual gas species present in the system – separating and quantifying every component of the residual gas environment, from water vapour and nitrogen to process gases and trace contaminants.

Pre-process: vacuum quality and fault diagnostics

Before a deposition run begins, the RGA provides a complete picture of the vacuum environment.

It detects air leaks by identifying nitrogen and oxygen signatures, distinguishes real leaks from virtual leaks and outgassing, identifies hydrocarbon contamination from pump back streaming, and confirms that the chamber has reached the cleanliness required for the process.

This pre-process qualification step prevents wasted runs and protects sensitive processes from contamination-related failures.

The RGA is equally valuable for ongoing fault diagnostics – detecting subtle system changes such as a degrading seal, a contaminated gas line, or a shift in base pressure that might otherwise go unnoticed until film quality is compromised.

In-process: partial pressure control of reactive gases

During reactive deposition, the RGA operates as a real-time process sensor. By continuously monitoring the partial pressure of the reactive gas – oxygen, nitrogen, or another process gas – it provides a precise in-situ feedback signal that the control system uses to regulate gas flow dynamically.

This ensures that the reactive gas partial pressure stays exactly at the setpoint throughout the run, independent of variations in pumping speed, chamber outgassing, or target condition.

Used alongside PEM, RGA-based partial pressure control adds an additional layer of process stability, particularly valuable in processes where both gas composition and plasma state need to be controlled simultaneously.

Integrated into Polyteknik control software

PEM and RGA do not operate as standalone instruments – they are fully integrated into the Polyteknik deposition control platform. Sensor signals, setpoints, feedback loops, and process logs are managed within a single software environment, giving operators a unified view of the entire process. Alarm thresholds, automated responses, and data logging run continuously, reducing operator workload and creating a complete audit trail for every deposition run.

This tight integration means that in-situ process control is not an add-on, it is a native part of how a Polyteknik system operates.

Key benefits

Repeatable film composition and stoichiometry across runs
Higher throughput compared to RF sputtering of compound films
Early detection of vacuum faults before they affect film quality
Reduced scrap and process downtime
Suitable for oxide, nitride, oxynitride, and other reactive PVD processes
Fully automated closed-loop operation with no manual gas flow adjustment required

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Whether you are specifying a new system, scaling an existing process, or evaluating PVD for a new application — contact the Polyteknik team for a technical discussion tailored to your requirements.

+45 9689 2800