Semiconductor Cavity Bore Formation With Two-Step Laser Ablation
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Solution Overview
Problem
Conventional methods for forming bores in semiconductor layer stacks are costly and prone to particle or fume contamination, which can damage devices during the laser drilling process.
Innovation Solution
A method involving two laser ablation steps is used to form a bore within a semiconductor layer stack, where the first partial bore is drilled with a high ablation speed and the second partial bore is drilled with a lower ablation speed, minimizing particle and fume ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laser drilling is used to form a bore through the semiconductor substrate, then the bore can be formed, but particles or fumes are generated that can contaminate the cavity and damage semiconductor devices
Solution Approach 1:
The bore formation process is divided into two sequential steps: first forming a partial bore from the first substrate surface to a depth that stops before reaching the cavity, then forming a second partial bore from the second substrate surface to connect to the first partial bore. This segmentation prevents direct laser drilling into the cavity, thereby avoiding particle and fume contamination while maintaining bore formation effectiveness.
2Productivity
If a single high-speed laser ablation step is used to form the bore, then the process is fast, but it causes significant particle generation and potential damage to semiconductor devices
Solution Approach 1:
The single high-speed ablation step is segmented into two controlled ablation steps. The first step forms the initial partial bore with controlled depth, and the second step completes the bore connection. This segmentation allows each step to be optimized for lower energy input, reducing particle and fume generation while maintaining acceptable overall process speed.
Solution Approach 2:
Instead of using excessive laser energy in a single step that causes damage, the process applies partial action in two controlled stages. Each stage uses appropriate energy levels for its specific purpose, avoiding the excessive energy input that would generate harmful particles and fumes while still achieving complete bore formation.
3Manufacturing precision
If conventional etching processes are used to form the bore, then the bore can be formed with precision, but the process is costly and time-consuming
Solution Approach 1:
The conventional mechanical or chemical etching process is replaced with a laser-based ablation process. Laser ablation provides precise bore formation through controlled material removal by light energy, eliminating the need for costly and time-consuming etching chemicals and equipment while maintaining manufacturing precision.
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 reduces the time and cost of bore formation, minimizes damage to semiconductor devices, and effectively prevents particle and fume contamination within the cavity.
Implementation Method 1
the first partial bore and the second partial bore are drilled by means of laser ablation
Implementation Method 2
the opening is sealed by melting and subsequent solidification by means of a further laser beam
Data Source
AI summary
A method for forming a bore for a cavity within a semiconductor layer stack. The method includes forming a first partial bore using a first laser ablation step starting at an outer surface of the stack so that the first partial bore extends with a first mean dimension and aligned in parallel with the outer surface, starting from the outer surface, and a bottom surface of the first partial bore lying between the outer surface and the cavity, and forming a second partial bore using a second laser ablation step started from the bottom surface of the first partial bore so that the second partial bore extends with a second mean dimension, aligned in parallel with the outer surface and is smaller than the first mean dimension, through the bottom surface into the cavity or an access channel opening at the cavity or connected to the cavity.