PVD — Physical Vapour Deposition

PVD is a thin film deposition process where material is physically ejected from a solid target (by sputtering or evaporation) and deposited on a substrate. In semiconductor manufacturing, sputtering PVD is used for metal films: barrier layers (TaN, TiN), seed layers for electroplating (Cu), and contact metals (Al, W, Co).

Why companies use it

·Sputtering PVD produces dense, high-purity metal films with controllable stress and composition
·Essential for depositing adhesion and barrier layers in copper dual-damascene interconnects
·Used for aluminium metallisation, contact silicides, and magnetic layers in memory (MRAM)
·Physical process (no precursor chemistry) gives very high film purity with minimal contamination

What hiring managers look for

·PVD is a fundamental process in every semiconductor fab — process engineers must understand the deposition mechanism and film properties
·Target lifetime management and end-of-life characterisation are practical skills that affect yield
·Understanding sputter yield, target erosion, and re-deposition is necessary for process control and chamber maintenance
·Candidates who can relate PVD film properties (resistivity, stress, grain structure) to device performance are highly valued

Typical interview questions

What is the difference between sputtering PVD and evaporation PVD?

How does magnetron sputtering improve upon conventional DC sputtering?

What is the purpose of the TaN/Cu PVD stack in copper dual-damascene interconnects?

How does substrate bias voltage affect PVD film properties?

What happens to film conformality in sputtering PVD compared to ALD and why?

Common mistakes

·Expecting PVD to conformally coat high-aspect-ratio features — line-of-sight deposition means PVD shadows deep trenches, unlike ALD or CVD
·Not monitoring target poisoning in reactive PVD (e.g., TiN deposition from Ti target in N₂/Ar) — composition and deposition rate shift as the target surface oxidises
·Ignoring the effect of base pressure on film purity — residual oxygen and water vapour are incorporated at low base pressure
·Failing to characterise end-of-target-life effects — sputtering yield and film properties change as the erosion groove deepens
·Not accounting for substrate temperature rise during PVD — the substrate heats during sputtering and can affect underlying films

Real engineering example

An interconnect process team found that contact resistance on a new chip node was 30% above target after PVD Co contact deposition. Analysis showed that the Co film had 800 ppm oxygen incorporation compared to 120 ppm on the reference process. Root cause: the loadlock O₂ level had increased due to a degraded gate valve seal, allowing moisture ingress during substrate transfer. Replacing the gate valve seal and implementing loadlock O₂ monitoring reduced incorporation to 150 ppm and recovered contact resistance targets.

Topics covered

PVDsputteringevaporationthin filmmetalbarriersemiconductormagnetron