Plasma Reactor Substrate Holder with Grounded Conductive Film
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Solution Overview
Problem
In semiconductor wafer processing, mechanical substrate holders with metal retaining rings experience parasitic etching, temperature unevenness, and metallic contamination due to ion bombardment, leading to reduced mechanical strength and non-homogeneous etching, and handling defects arise from electrostatic bonding with insulating materials during substrate removal.
Innovation Solution
A reactor design with electrically insulating mechanical holding means coated with an electrically conductive film, connected to ground to evacuate electrical charges and prevent electrostatic bonding, and a substrate holder connected to ground for improved polarization and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal retaining ring is used to hold the substrate, then mechanical strength and substrate holding ability are improved, but parasitic etching occurs on the retaining ring surface due to ion bombardment, reducing its mechanical strength and requiring frequent replacement
Solution Approach 1:
The patent applies this principle by making the retaining ring disposable - it is intentionally designed to be eroded by plasma and eventually destroyed during substrate processing. This eliminates the problem of parasitic etching accumulating and reducing mechanical strength, as the ring is replaced after each use rather than requiring frequent replacement due to degradation.
Solution Approach 2:
The patent applies this principle by creating a non-uniform structure on the retaining ring surface - a protrusion is formed at a specific location to concentrate ion bombardment and etching effects. This localizes the harmful etching action to a specific area, allowing the rest of the ring to maintain its structural integrity and mechanical strength for longer periods.
2Strength
If a metal retaining ring is used to hold the substrate, then substrate holding ability is improved, but temperature rises in the retaining ring due to ion bombardment, causing uneven temperature distribution in the substrate and non-homogeneous etching
Solution Approach 1:
The patent applies this principle by creating a localized protrusion structure on the retaining ring that concentrates thermal effects and ion bombardment in a specific area. This prevents heat from being distributed uniformly across the entire ring-substrate interface, thereby maintaining better temperature uniformity across the substrate surface and achieving more homogeneous etching results.
3Force
If a metal retaining ring is used to hold the substrate, then mechanical holding force is improved, but metallic contamination of the substrate surface occurs due to ion bombardment of the retaining ring
Solution Approach 1:
The patent applies this principle by using a disposable retaining ring that is intentionally designed to be consumed during the processing cycle. The ring is replaced after each substrate processing, which prevents metallic contamination from accumulating on substrates, as each new ring starts with a clean surface free from previous contamination.
4Stability of the object's composition
If an electrically insulating material is used for mechanical holding means, then polarization of the holding means is prevented, but electrostatic bonding occurs between the holding means and substrate during removal, causing handling defects
Solution Approach 1:
The patent applies this principle by extracting the electrical insulation property from the retaining ring material. Instead of using an insulating material, the ring is made conductive, which allows electrical charges to dissipate and prevents electrostatic bonding between the holding means and substrate during removal, thereby eliminating handling defects.
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
Prevents electrostatic sticking and ensures homogeneous etching by neutralizing electrical charges and reducing ion impact on holding means, maintaining substrate integrity and facilitating smooth handling during processing and removal.
Implementation Method 1
the film is electrically conductive, electrical connection means make it possible to selectively connect the electrically conductive film to ground
Implementation Method 2
the interior atmosphere of the reactor is a gaseous atmosphere at reduced pressure... flow of reactive ions coming from the plasma source
Implementation Method 3
the bombardment of the holding ring by the ions coming from the plasma causes a rise in the temperature of the holding ring
Implementation Method 4
The substrate temperature is generally controlled by controlling the temperature of the substrate holder, for example by circulating heat transfer fluids in the substrate holder, and by heating resistors installed inside the substrate holder
Implementation Method 5
heating resistors installed inside the substrate holder
Implementation Method 6
The heat exchange between the substrate and the substrate holder is ensured by means of a cushion of helium between the substrate holder and the corresponding adjacent face of the substrate
Data Source
AI summary
The reactor for etching a semiconductor substrate (2) or depositing chemical vapor assisted by plasma on the substrate, comprises a plasma source, a carrier-substrate (3), a unit (4) for polarizing the substrate and the carrier-substrate, and a mechanical maintenance unit (30) for covering the substrate against the carrier-substrate. The mechanical maintenance unit comprises an electrically insulating material that opposes the polarization of the maintenance unit by contact with the substrate. The electrically insulating material is covered with an electrically conducting aluminum film (34). The reactor for etching a semiconductor substrate (2) or depositing chemical vapor assisted by plasma on the substrate, comprises a plasma source, a carrier-substrate (3), a unit (4) for polarizing the substrate and the carrier-substrate, and a mechanical maintenance unit (30) for covering the substrate against the carrier-substrate. The mechanical maintenance unit comprises an electrically insulating material that opposes the polarization of the maintenance unit by contact with the substrate. The electrically insulating material is covered with an electrically conducting aluminum film (34) in a zone of contact with the substrate. Electrical connection unit is arranged to connect the carrier-substrate to a ground of the conducting film. The electrically insulating material forms an insulating body of the maintenance unit. The maintenance unit comprises a metallic body connected to the ground. A layer of the insulating material covers the metallic body according to a support face against the substrate. The electrical connection unit is repelled by the maintenance unit towards the carrier-substrate, when the conducting film is resting against a periphery of an active face of the substrate, and exceeds beyond the surface of the carrier-substrate, when the maintenance unit differs from the substrate active face. The electrical connection unit ensures a conduction of calorific energy simultaneously to the electricity conduction between the carrier-substrate and the maintenance unit. The mechanical maintenance unit comprises a maintenance ring.