Gate Spacer Recessing for Metal Silicide Formation Between Dense Gates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As the distance between gates shortens in semiconductor manufacturing, it becomes difficult to remove the salicide blocking (SAB) layer between gates, leading to poor formation of metal silicide.
Innovation Solution
The semiconductor structure and manufacturing method involve forming gate structures with first and second spacers, where the second spacers have an upper recess. A protective layer is formed to expose the upper portions of the second spacers, which are then etched to enlarge the distance between them. This allows for effective removal of the SAB layer and formation of a good metal silicide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the distance between gates is shortened to increase device density, then productivity is improved, but the difficulty of removing SAB layer increases leading to poor metal silicide formation
Solution Approach 1:
The spacer structure is divided into two distinct segments: a first spacer portion and a second spacer portion with different heights. The second spacer portion is taller and positioned to provide enhanced spacing between adjacent gate structures. This segmentation allows the taller second spacer to prevent SAB layer encroachment into the metal silicide formation region, thereby maintaining manufacturing precision even when gate distances are shortened for higher device density.
2Area of stationary object
If the distance between gates is shortened, then area is reduced improving device density, but the SAB layer removal becomes more difficult
Solution Approach 1:
The solution introduces a vertical dimension differentiation by creating spacers with varying heights. The second spacer portion extends taller than the first spacer portion, creating a stepped configuration. This vertical dimension change provides an additional protective barrier that prevents SAB layer from reaching the metal silicide formation region, making SAB layer removal easier even when horizontal gate spacing is reduced.
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 enlarged distance between the second spacers facilitates the removal of the SAB layer, enabling the formation of a good metal silicide in the predetermined region, thereby improving the semiconductor structure's performance.
Implementation Method 1
A reactive ion etching (RIE) process is performed to the second spacers with an etching gas to form the protective layer, and the part of the upper portions of the second spacers is removed simultaneously. The etching gas includes a chlorine gas (Cl2), an oxygen gas (O2), and an inert gas.
Data Source
AI summary
A manufacturing method of the semiconductor structure including the following is provided. Gate structures are formed on a substrate. Each gate structure includes a gate, a first spacer, and a second spacer. The gate is disposed on the substrate. The first spacer is disposed on a sidewall of the gate. The second spacer is disposed on the first spacer. In a region between two adjacent gate structures, the first spacers are separated from each other, and the second spacers are separated from each other. A protective layer is formed between the two adjacent gate structures. The protective layer covers lower portions of the second spacers and exposes upper portions of the second spacers. A part of the upper portions of the second spacers is removed using the protective layer as a mask to enlarge a distance between the upper portions of the second spacers. The protective layer is removed.