PVD Chamber Shield Deflects Particles via Electromagnetic Fields
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Solution Overview
Problem
In physical vapor deposition (PVD) systems, high power density sputtering with high magnetic fields causes significant thermal issues in the sputtering target, leading to mechanical bowing, particle generation, and defects on the substrate and chamber components, particularly when processing larger wafers, due to inadequate cooling and thermal stress.
Innovation Solution
A physical vapor deposition chamber design featuring a shield with a cylindrical body and a first electrode assembly positioned to laterally displace particles generated during the process, combined with a magnet to prevent these particles from contacting the substrate, using a combination of electric and magnetic fields to maintain plasma stability and reduce target deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high power density sputtering with high magnetic fields is used, then sputtering rate is enhanced, but target temperature rises causing mechanical bowing and particle generation
Solution Approach 1:
A shield structure is introduced as an intermediary component between the sputtering target and substrate. The shield captures and redirects particles that would otherwise reach the substrate, while also providing additional cooling surface area to manage target temperature. This mediator approach allows high power density sputtering to continue while preventing the harmful effects of hot particles from reaching the substrate.
2Temperature
If cooling fluid is used to cool the target backing plate, then some heat is removed, but thermal gradient causes mechanical bowing that increases with larger wafer size
Solution Approach 1:
The cooling system is segmented into multiple independent cooling zones within the backing plate, each capable of being controlled separately. This allows differential cooling rates across the target surface, compensating for thermal gradients and reducing mechanical bowing. The shield structure is also segmented into multiple sections that can be independently positioned to capture particles from different regions of the target.
3Productivity
If larger size wafers are processed, then production capacity increases, but gravitational and thermal loads increase target deformation
Solution Approach 1:
Additional support structures and reinforcement elements are introduced to counterbalance the increased gravitational and thermal loads from processing larger wafers. The shield structure serves a dual function: it captures particles and also provides mechanical support to reduce target deformation under load. The backing plate is reinforced with additional ribs and support elements that act as counterweights to prevent excessive bowing.
4Productivity
If high magnetic fields are applied to increase plasma density, then sputtering rate increases, but particle generation and re-sputtering increase
Solution Approach 1:
The shield structure is designed to capture the harmful particles generated by high magnetic field sputtering and redirect them onto sacrificial surfaces or back toward the target. This converts the harmful particle flux into a beneficial effect by preventing substrate contamination while the particles continue to contribute to the sputtering process. The shield effectively transforms a harmful byproduct into a useful component of the deposition process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces particle deposition on substrates, maintains plasma stability, and prevents mechanical stress on the target, enhancing the deposition process and reducing defects in EUV mask blanks and other PVD applications.
Implementation Method 1
a first electrode assembly positioned on an inner surface of the shield, and a magnet positioned on the inner surface of the shield. The first electrode assembly is positioned and configured to create an electromagnetic field that laterally displaces particles generated during a physical vapor deposition process
Implementation Method 2
the first electrode assembly and the magnet cooperate to prevent the particles from contacting a substrate on the substrate support during the physical vapor deposition process
Implementation Method 3
Sputtering, alternatively called physical vapor deposition (PVD), has long been used in depositing metals and related materials in the fabrication of semiconductor integrated circuits
Implementation Method 4
Plasma sputtering typically includes a magnetron positioned at the back of the sputtering target to project a magnetic field into the processing space to increase the density of the plasma
Implementation Method 5
The sputtering target is cooled by contacting a target backing plate with cooling fluid
Data Source
AI summary
Physical vapor deposition processing chambers and methods of processing a substrate such as an EUV mask blank in a physical vapor deposition chamber are disclosed. An electric field and a magnetic field are utilized to deflect particles from a substrate being processed in the chamber.