Two-Step PSG Deposition Reducing Flower Pattern Size
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing high-density plasma chemical vapor deposition (HDP CVD) process for forming phosphosilicate glass (PSG) at the 130 nm technology node and below is prone to forming flower-shaped crusts, known as 'flower patterns,' which can lead to instability and variability in device performance due to non-uniform phosphorus concentration and etching issues.
Innovation Solution
A two-step deposition method using HDP CVD with modified sputtering deposition ratios, where the first PSG layer has a sputtering deposition ratio of 0.10 to 0.16 and the second layer has a ratio of 0.18 to 0.22, with the first layer contributing 5-30% and the second layer contributing 70-95% to the total thickness, respectively, to control and minimize flower pattern size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-step HDP CVD process is used to deposit PSG, then the deposition process is simple and fast, but flower-shaped crusts form with non-uniform phosphorus concentration
Solution Approach 1:
The single-step deposition process is divided into two sequential steps with different sputtering deposition ratios. The first step uses a lower ratio (0.10-0.16) to deposit an initial PSG layer with controlled phosphorus concentration, while the second step uses a higher ratio (0.18-0.22) to complete the deposition. This segmentation eliminates flower pattern formation while maintaining overall deposition efficiency and achieves uniform phosphorus concentration throughout the PSG layer.
2Manufacturing precision
If helium is used as sputtering gas in HDP CVD, then gap-fill requirements are met, but flower patterns are formed over pattern areas
Solution Approach 1:
The sputtering deposition ratio parameter is changed between two deposition steps. The first step uses a lower ratio (0.10-0.16) that prevents excessive phosphorus accumulation and flower pattern formation, while the second step uses a higher ratio (0.18-0.22) to achieve the required gap-fill quality. This dynamic parameter adjustment maintains both gap-fill performance and pattern area integrity.
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 flower pattern size by approximately 50% in height and 30% in crust thickness, preventing clipping and sidewall voids, thereby enhancing phosphorus concentration uniformity and etching uniformity.
Implementation Method 1
high-density plasma chemical vapor deposition (HDP CVD)
Implementation Method 2
high-density plasma chemical vapor deposition (HDP CVD)
Implementation Method 3
modified sputtering deposition ratios
Data Source
AI summary
A method of depositing phosphosilicate glass (PSG) is disclosed. The method includes a first deposition step for depositing a first PSG layer with a sputtering deposition ratio of 0.10 to 0.16, and a second deposition step for depositing a second PSG layer with a sputtering deposition ratio of 0.18 to 0.22 after the first deposition step. The first PSG layer has a thickness smaller than that of the second PSG layer. With such two-step deposition method, flower pattern having a dramatically reduced size can be formed without occurrence of clipping or formation of sidewall voids in the resultant gate patterns. Specifically, the formed flower pattern has a height reduced by about 50% and a thickness reduced by about 30%.