Piezoelectric Layer Thinning via Ion Implantation and CMP

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Solution Overview

Problem

Existing methods for manufacturing thin layers of piezoelectric materials on substrates, such as the Smart Cut™ process, result in surface defects due to grinding, leading to non-uniformity and degradation of electrical characteristics.

Innovation Solution

Implanting ions, such as hydrogen, helium, and oxygen, into the upper portion of the piezoelectric layer to amorphize it, followed by chemical mechanical polishing to remove the amorphized portion, thereby enhancing the etching rate and minimizing surface defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If grinding is used to thin the piezoelectric layer, then the layer thickness is reduced, but surface defects are generated

Engineering Contradiction:

Improvelayer thicknessVSAvoidsurface quality

Core Design Contradiction:

Length of stationary objectVSManufacturing precision

Solution Approach 1:

Ion implantation is performed as a preliminary action before polishing to modify the upper portion of the piezoelectric layer. The ion implantation creates an amorphized or damaged layer that is more susceptible to removal, enabling selective removal of the ground surface while preserving the underlying intact layer and eliminating surface defects

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The ion implantation process creates local quality differences within the piezoelectric layer by modifying only the upper portion (within a controlled depth range) while leaving the lower portion intact. This local modification enables selective removal of the damaged surface layer through polishing, resolving the contradiction between thickness reduction and surface quality

Inventive Principle:

Principle #3Local quality

2Productivity

If ion implantation is used to amorphize the upper portion, then the etching rate is enhanced, but the process complexity increases

Engineering Contradiction:

Improveetching rateVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical etching methods with ion implantation followed by chemical mechanical polishing. The ion implantation process uses ion beams to amorphize the material, and the subsequent polishing uses chemical-mechanical reactions to remove the amorphized layer. This substitution achieves higher etching rates and better surface quality compared to purely mechanical methods, justifying the increased process complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The method achieves a smooth, defect-free thin layer of piezoelectric material with improved uniformity and electrical properties, ensuring faster removal of the amorphized portion compared to the underlying intact layer.

Implementation Method 1

a. implanting ions into the first layer so as to amorphize an upper portion of the first layer

Methodology Applied

Scientific EffectIon implantation: Ion Implantation

Implementation Method 2

removing the upper portion by a chemical mechanical polishing step

Methodology Applied

Scientific EffectChemical mechanical polishing:

Data Source

PatentEP4583401A1Process for thinning a layer of piezoelectric material

Publication Date: 2025.07.09 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

Figure 1A~1C
Figure 2~4
Figure 5

AI summary

The present description relates to a method of thinning a first layer (10) of a piezoelectric material comprising: a. implanting ions into the first layer (10) so as to amorphize an upper portion (10a) of the first layer (10), and b. removing the upper portion (10a) by a chemical-mechanical polishing step.