Setting a New Standard for Deposition Excellence

In the race to meet ever-tightening demands of microelectronics and optical device manufacturing, precision and repeatability are no longer luxuries — they're requirements. KDF Technologies' Enhanced Rotating Planetary Pallet (ERPP) is a breakthrough in sputtering system design that delivers metallic film uniformity better than ±1% and repeatability exceeding ±0.5%.

By combining advanced planetary motion with linear scanning, the ERPP architecture redefines what's possible in thin film deposition. Whether you're engineering multilayer conductive barriers for integrated circuits or optimizing titanium tungsten coatings for acoustic filters, this next-generation platform ensures unmatched consistency, surface quality, and process control.

How the ERPP Achieves Superior Uniformity

Metallic coatings deposited using the KDF ERPP exhibit exceptionally high film uniformity and tight process repeatability. This performance is driven by the synergistic combination of planetary revolution and the system's standard linear scanning mode.

KDF Technologies has developed both reactive and non-reactive sputtering processes for metallic, semi-metallic, semiconductor, and dielectric materials. These processes consistently achieve film uniformity better than ±1% across the pallet, with repeatability exceeding ±0.5% from pallet to pallet — enabling high-performance processing of multilayer conductive barriers and contact materials essential for integrated circuits.

The KDF 900 series sputtering tools employ a combination of linear scanning and sophisticated rotating motion. The ERPP ensures that all areas of the substrate are exposed to sputtered material from various angles — averaging out the angular distribution of sputtered atoms while linear motion compensates for non-uniform target erosion and plasma density variations. Together, both mechanisms maximize exposure to sputtered flux from all directions, eliminating spatial non-uniformities in the sputtering plume.

The Planetary Motion Design

At the heart of the ERPP is an elegant mechanical architecture. On top of the pallet sits a rotating platform — the "sun" — which rotates continuously over a broad range of speeds. Mounted to this platform are four wafer holders, each accommodating a 4-inch-diameter wafer — referred to as "planets."

Each planet rotates at a fixed gear ratio relative to the sun, generating a full planetary motion of the wafers within the deposition plane. This motion is superimposed onto the standard linear translation of the pallet underneath the target. By integrating both rotational and translational movement, the planetary architecture:

• Averages out spatial variations in deposition rate across the cathode
• Reduces edge-to-center thickness variation significantly
• Improves step coverage on 3D features by varying the incident deposition angle
• Enhances surface morphology through programmable rotation speed control
• Maintains compatibility with standard KDF linear translation systems

Standard Deposition vs. ERPP Enhancement

Standard Deposition Process

On standard KDF sputtering tools, metallic films such as tungsten (W) and titanium tungsten (TiW) are deposited onto a 12" × 12" pallet deposition zone, which scans across a 15" × 5" rectangular magnetron cathode. Deposition is performed via DC magnetron sputtering — either reactively using oxygen or nitrogen with elemental targets, or non-reactively from compound targets.

The cathode is engineered to optimize uniformity for metallic films, achieving an average thickness variation of approximately ±2% across four 4" wafers mounted on a planetary rotating pallet.

ERPP Enhanced Process

In advanced microelectronic applications, tungsten films are critical layers within frequency-selective components such as Surface Acoustic Wave (SAW) and Bulk Acoustic Wave (BAW) filters. For Solidly Mounted Resonator (SMR) configurations in BAW filters, multilayer silicon-based stacks require exceptional film uniformity and run-to-run thickness repeatability on the order of ±1%.

Since resonant frequency is inversely proportional to the thickness of constituent layers — including tungsten — precise thickness control is essential for accurate frequency tuning. KDF 900 series systems equipped with three- or four-target configurations, precisely controlled scan speeds, and multistep recipe capabilities are purpose-built for these demanding applications.

Measured Performance Data

Tungsten (W) and titanium tungsten (TiW) films were deposited non-reactively using elemental W and TiW targets. The results confirm the ERPP's capability for high-precision thin film deposition across all key metrics:

Sheet Resistance

Figure 3 illustrates a reduction in sheet resistance with increasing setpoint values under constant linear scanning conditions. Wafer rotation during sputtering was found to significantly enhance thin-film uniformity — the rotational motion averages out spatial non-uniformities inherent in the sputtering process, improving thickness uniformity and stabilizing critical film properties such as sheet resistance. The decrease in sheet resistance with increasing setpoint values suggests potential microstructural improvements, including enhanced film density and grain structure.

Uniformity Performance

Figure 4 presents uniformity results for W and TiW films deposited with the ERPP-enabled KDF 900 system. The planetary scanning motion consistently achieved:

• Within-wafer uniformity better than ±1% across all tested processes
• Pallet-wide uniformity better than ±2% — a significant improvement over standard ±2% baseline
• Consistent performance confirmed across multiple deposition runs

Surface Roughness

Figure 5 demonstrates significant improvements in surface roughness. While wafer rotation contributes to enhanced thickness uniformity, its influence on surface roughness is multifaceted. Depending on process parameters — rotation speed, deposition pressure, and target power — surface roughness may either increase or decrease. Careful optimization of sputtering conditions is therefore essential to achieve the desired film characteristics for each specific application.

Discussion & Future Applications

The ERPP represents a significant advancement in metallic film deposition technology. This technique has reduced metallic film non-uniformities from typical values of ±2% to less than ±1% across the pallet for non-reactive deposition processes — a measurable, repeatable improvement that directly supports next-generation device manufacturing requirements.

For production engineers working in semiconductor, photonics, BAW/SAW filter manufacturing, or advanced materials research, the ERPP-equipped KDF 900 series represents the current state of the art in batch inline sputtering uniformity.