Semiconductor Spacer Structure for Void-Free Gap Filling
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Solution Overview
Problem
The increasing aspect ratio of gaps between gate structures in semiconductor devices poses a challenge for effective gap-filling with insulating materials, leading to difficulties in achieving optimal device performance and reducing the likelihood of void formation.
Innovation Solution
The method involves forming spacers with a partially removed top portion, resulting in a gap with a smaller aspect ratio, which allows for better gap-filling by inter-layer dielectric materials and reduces the likelihood of voids, thereby improving the semiconductor device's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional gap-filling methods are used with high aspect ratio gaps, then the fabrication process becomes difficult and voids form, but modifying the spacer structure adds process complexity
Solution Approach 1:
The spacer structure is segmented into two distinct portions: a first portion with a first height and a second portion with a second height that is less than the first height. This segmentation allows the gap to be filled more effectively by reducing the aspect ratio, while the segmented spacer can be formed through selective etching processes that target different portions of the spacer differently, thus improving gap-filling quality without excessive overall complexity
Solution Approach 2:
Different portions of the spacer are given different local properties through the height differentiation. The first portion maintains full height to provide structural support, while the second portion is reduced in height to facilitate better gap-filling access. This local quality variation allows the structure to simultaneously provide mechanical support and enable effective material deposition in the gap region
2Reliability
If the spacer top portion is removed to lower aspect ratio, then gap-filling improves, but additional etching steps are required
Solution Approach 1:
The spacer structure is prepared in advance with a pre-formed segmented configuration before the gap-filling process begins. By preliminarily creating the height-differentiated spacer structure, the subsequent gap-filling operation can proceed more effectively without requiring complex real-time adjustments or multiple corrective steps, thus improving reliability while managing manufacturing complexity
Solution Approach 2:
The segmented spacer acts as an intermediary structure that mediates between the gate structures and the gap-filling material. The reduced-height second portion serves as a mediator that facilitates material access into the gap region, while the full-height first portion maintains structural integrity, thus improving void formation likelihood without requiring direct complex manipulation of the gap region itself
Data Source
AI summary
Semiconductor devices and methods of forming the same are disclosed. A semiconductor device includes a substrate, a gate structure over the substrate, a spacer and a source/drain region. The gate structure is disposed over the substrate. The spacer is disposed on a sidewall of the gate structure, wherein the spacer has a top surface lower than a top surface of the gate structure. The source/drain region is disposed adjacent to a sidewall of the spacer.