Single Wafer Wet Etching for TSV Reveal Height Control
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Solution Overview
Problem
The conventional process for thinning semiconductor wafers to reveal Through Silicon Vias (TSVs) is complex and costly, involving multiple steps like grinding and chemical mechanical planarization, which lacks precision and uniformity, and does not effectively remove residual potassium ions affecting electrical properties.
Innovation Solution
A system and method for wet etching semiconductor wafers using a single wafer processing system with real-time thickness measurement and automated substrate transfer, incorporating an etching station with end-point detection and cleaning capabilities to achieve precise and uniform etching, and remove residual potassium ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional multistep process (grinding, CMP, plasma etching) is used to thin silicon wafer, then bulk silicon removal is achieved, but process complexity and cost increase
Solution Approach 1:
The patent combines multiple process steps (grinding, CMP, plasma etching) into a single wet etching process. The wet etching process uses a chemical solution to remove silicon dioxide and expose TSVs in one step, eliminating the need for separate grinding, CMP, and plasma etching steps, thereby reducing process complexity while maintaining thinning precision.
Solution Approach 2:
The patent changes the etching parameters by using wet chemical etching instead of mechanical or plasma-based methods. By controlling the wet etching process parameters (etchant composition, temperature, time), the patent achieves precise wafer thinning and TSV exposure, simplifying the overall process while maintaining manufacturing precision.
2Manufacturing precision
If complete grinding of substrate is performed to expose conductor, then via exposure is achieved, but ions are smeared across surface altering electrical properties
Solution Approach 1:
The patent replaces the mechanical grinding process with a chemical wet etching process. Instead of mechanically removing material with abrasive wheels that cause ion smearing, the wet etching uses chemical solutions to selectively remove silicon dioxide and expose TSVs, eliminating the harmful mechanical action that causes ion contamination and electrical property alteration.
3Ease of manufacture
If adhesive layer is used to mount wafers, then carrier mounting is achieved, but thickness measurement accuracy is reduced
Solution Approach 1:
The patent extracts or removes the adhesive layer from the measurement process. By using wet etching that does not require adhesive mounting, or by removing the adhesive layer before measurement, the patent eliminates the interference that adhesive thickness variation causes to measurement accuracy, while still maintaining ease of manufacture through simplified processing.
4Device complexity
If batch processing or immersion processing is used, then processing is simplified, but control precision decreases as wafer sizes increase
Solution Approach 1:
The patent employs a single-wafer processing system where each wafer is processed individually with controlled dispensing of etchant. This self-service approach allows precise control of etching parameters for each wafer, ensuring uniform etching results even as wafer sizes increase, while maintaining relatively simple system complexity through automated single-wafer handling.
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 system enables precise and uniform etching of semiconductor wafers, ensuring accurate exposure of TSVs and improving yield by minimizing residual potassium ions, thus reducing costs and complexity compared to traditional methods.
Implementation Method 1
an imaging device configured to measure an initial thickness information and a final thickness information for a substrate in real time
Implementation Method 2
a single wafer wet etching device... wet etching process... liquid chemical etchant to remove material from or on the substrate
Implementation Method 3
an end-point detection device... emitting light onto at least a sample area of a surface of the particular substrate and detecting a reflection of the light off of the sample area
Data Source
AI summary
A system and method for performing a wet etching process is disclosed. The system includes multiple processing stations accessible by a transfer device, including a measuring station to optically measure the thickness of a substrate, a controller to calculate an etch recipe for the substrate, in real time, and cause a single wafer wet etching station to etch the substrate according to the recipe. In addition, the system can measure the after etch thickness and calculate etch recipes, in real time, as a function of the final measurements of a previous substrate. The system can also include an in situ end point detection device for detecting the TSV reveal point while etching TSVs substrates. The system provides an automated solution to adjust etch recipe parameters in real time according to feedback concerning previously etched wafers and precisely control the TSV reveal height and etch duration using end point detection.