Angled Trench Test Pattern for Accurate Polysilicon Depth Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional test patterns for polysilicon etching back in semiconductor manufacturing face challenges in accurately determining trench depth due to limitations in trench width, where widths that are too small result in incorrect scanning parameters and widths that are too large cause polysilicon to grow into undesirable shapes, preventing accurate surface profilometry results.
Innovation Solution
A test pattern with trenches formed on a substrate at a preset angle greater than or equal to 10°, preferably 30°, and with widths ranging from 0.18 to 0.36 microns, and depths from 0.98 to 2.02 microns, allowing for increased scanning length while maintaining a constant conventional width, enabling accurate scanning parameters to be obtained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the width of the test pattern (trench) is increased to provide sufficient scanning length for surface profilometry, then the scanning length is improved, but the polysilicon grows into a shape with higher sidewalls and lower middle portion due to filling features, causing incorrect scanning parameters
Solution Approach 1:
The patent rotates the trench orientation by 45 degrees relative to the wafer scribing lines, changing the spatial dimension of the test pattern. This dimensional change allows the trench to span across multiple scribing lines, effectively increasing the scanning length available for surface profilometry without requiring an increase in trench width that would cause polysilicon shape distortion
2Manufacturing precision
If the width of the test pattern (trench) is decreased to maintain proper polysilicon growth shape, then the trench shape accuracy is improved, but the scanning length becomes insufficient for accurate surface profilometry measurements
Solution Approach 1:
By orienting the trench at a 45-degree angle to the wafer scribing lines, the patent exploits the extended dimension created by crossing multiple scribing lines. This allows the scanning length to be increased without increasing the trench width, thereby maintaining proper polysilicon growth shape while providing sufficient scanning length for accurate measurements
Data Source
AI summary
A test pattern for testing a trench POLY over-etched step is provided. The test pattern is a trench (14) formed on a substrate (1); the trench (14) comprises a bottom surface and two side surfaces extending from the bottom surface; the trench (14) is formed on the substrate (1) with a preset angle of non-90° formed between the longitudinal direction (L) thereof and the longitudinal direction (X) of a wafer scribing trench. The test pattern can extend the scanning length of a step scanning equipment without changing the width of the trench.