Silicon Wafer Deformation Prevention via Segmented Frame

Solution Overview

Problem

The existing manufacturing process for silicon watch components, such as hairsprings and balance wheels, faces issues with deformation and irreversibility during thermal oxidation, leading to damage and unusability, and previous solutions like using a support plate are cumbersome and time-consuming.

Innovation Solution

A process involving a silicon-on-insulator substrate with a silicon dioxide intermediate layer, where a detachment groove is engraved in the second silicon layer to create a blind portion that links with the first layer, allowing partial removal of the intermediate layer without complete detachment, maintaining structural integrity and enabling orientation-independent processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wafer is heated to high temperatures in a thermal oxidation furnace, then the surface condition of the parts is improved and mechanical resistance is increased, but the wafer bends under its own weight causing deformation and damage

Engineering Contradiction:

Improvemechanical resistanceVSAvoidwafer deformation

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The second silicon layer is segmented into a retained portion (forming the frame) and a detached portion (removed to release the parts). This segmentation allows the wafer to be divided into a rigid supporting frame and a removable section, enabling the frame to maintain wafer rigidity during thermal processing while the detached portion can be removed afterward to release the manufactured parts.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution transitions from a two-layer structure to a three-layer structure (first silicon layer, silicon dioxide intermediate layer, second silicon layer with frame) by adding the intermediate layer as a sacrificial element. This dimensional addition allows for controlled separation: the intermediate layer is removed to detach the second layer's frame portion, creating a self-supporting rigid frame that prevents deformation during thermal oxidation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the wafer is deformed during thermal oxidation, then the deformation is permanent and irreversible, but this precludes use in other equipment such as balance spring stiffness measuring equipment

Engineering Contradiction:

Improvesurface condition improvementVSAvoidreusability of wafer

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The second silicon layer is segmented into a retained portion (forming the frame) and a detached portion (removed to release the parts). This segmentation allows the wafer to be divided into a rigid supporting frame and a removable section, enabling the frame to maintain wafer rigidity during thermal processing while the detached portion can be removed afterward to release the manufactured parts.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sacrificial silicon dioxide intermediate layer is selectively removed (discarded) in the detachment groove area, allowing the second silicon layer to be detached and discarded in that region, while the retained portion of the second layer forms a permanent rigid frame that is recovered and reused for supporting the manufactured parts during subsequent processes.

Inventive Principle:

Principle #34Discarding and recovering

3Shape

If a support plate is used to prevent wafer deformation during oxidation-deoxidation operations, then deformation is prevented, but the mounting and turning operations are long and tedious

Engineering Contradiction:

Improvewafer deformation preventionVSAvoidmounting and turning time

Core Design Contradiction:

ShapeVSLoss of time

Solution Approach 1:

The wafer's own second silicon layer is configured to serve as its own support structure during thermal processing. By retaining a portion of the second layer as a rigid frame, the wafer becomes self-supporting and does not require external support plates or manual positioning operations, eliminating the time-consuming mounting and turning steps while still preventing deformation.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The detachment groove is etched into the second silicon layer before thermal oxidation, pre-configuring the wafer's structural properties. This preliminary action creates the rigid frame structure in advance, so that during subsequent thermal processing the wafer automatically maintains its shape without requiring real-time intervention or external support devices.

Inventive Principle:

Principle #10Preliminary action

4Ease of manufacture

If the intermediate layer is completely removed to detach the portion, then the parts are released, but the structural integrity and rigidity are compromised

Engineering Contradiction:

Improveparts detachmentVSAvoidwafer rigidity

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The second silicon layer is segmented into a retained portion (forming the frame) and a detached portion (removed to release the parts). This segmentation allows the wafer to be divided into a rigid supporting frame and a removable section, enabling the frame to maintain wafer rigidity during thermal processing while the detached portion can be removed afterward to release the manufactured parts.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The intermediate layer is selectively removed only in the detachment groove area where part release is needed, while being preserved in other areas to maintain the structural integrity of the frame. This local differentiation allows the wafer to have both rigidity (where the intermediate layer is present) and ease of detachment (where it is removed).

Inventive Principle:

Principle #3Local quality

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 method prevents deformation during subsequent treatments, allows for easier detachment of silicon parts, and simplifies the separation process, maintaining the structural integrity of the components and facilitating their use in various applications.

Implementation Method 1

at least one portion called the blind portion of the detachment groove being etched so that a part of the second layer, forming a bond, is retained in line with said portion

Methodology Applied

Scientific EffectMechanical bonding:

Implementation Method 2

the intermediate layer is partially removed by eliminating the silicon dioxide in line with said at least one portion to be detached or the anticipated location of said portion to be detached

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 3

a part of the second layer, forming a bond, is retained in line with said portion

Methodology Applied

Scientific EffectMaterial bonding:

Data Source

PatentEP4227742B1Method for manufacturing a silicon part

Publication Date: 2024.11.13 SIGATEC

Figure 1A~1E
Figure 1F~1J
Figure 1K~1M

AI summary

The present invention relates to a method for manufacturing a silicon part, in which a) a substrate (1000) is provided comprising a first layer (10) of silicon, an intermediate layer (30) of silicon dioxide, and a second layer (20) of silicon, b) the first layer (10) is etched to form at least one part, c) in the second layer (20), a detachment groove (200) is etched to delimit a portion to be detached (21), at least a portion (220) of the detachment groove (200) being etched so that a part (222) of the second layer, forming a bond, is retained opposite said portion (220), d) the intermediate layer (30) is partially removed by eliminating the silicon dioxide, e) the portion to be detached is mechanically separated from the rest of the substrate by breaking the bond (222).