Cyclic PE-Ti Silicide Deposition for Si Over SiN Selectivity
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Solution Overview
Problem
Conventional plasma enhanced-titanium (PE-Ti) deposition methods fail to meet the selectivity requirements for depositing on silicon (Si) versus silicon nitride (SiN) in next-generation semiconductor devices, leading to thick Ti deposits on dielectric materials and the need for additional wet etch processes.
Innovation Solution
A cyclic plasma enhanced-titanium (PE-Ti) deposition method combined with thermal annealing or TiCl4 soak processes is employed to enhance the selectivity of TiSi layer formation on Si surfaces relative to SiN surfaces, reducing Ti buildup on dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional PE-Ti deposition is used, then Ti layer can be deposited on Si and SiN surfaces, but thick Ti deposits form on dielectric material (SiN) sidewalls reducing selectivity
Solution Approach 1:
The deposition process is segmented into multiple cycles of plasma exposure followed by thermal annealing or TiCl4 soak steps. Each cycle deposits a thin Ti layer on Si surfaces while the subsequent annealing or soak step selectively removes excess Ti from SiN surfaces, achieving cumulative selectivity improvement without requiring thick initial deposits
Solution Approach 2:
The patent employs periodic cycling between deposition and removal steps. Multiple cycles of plasma deposition followed by thermal annealing or TiCl4 soaking create a rhythmic process where Ti accumulates on Si surfaces while being periodically removed from SiN surfaces, achieving high selectivity through repeated small improvements rather than a single high-selectivity deposition step
2Productivity
If conventional PE-Ti deposition is used, then Ti layer forms on contact structure, but additional wet etch procedure is required to remove Ti from dielectric sidewalls
Solution Approach 1:
The harmful effect of Ti deposition on SiN surfaces is extracted and removed through selective thermal annealing or TiCl4 soaking steps that occur after each deposition cycle. This eliminates the need for separate wet etch procedures by incorporating the removal function within the cyclic deposition process itself
Solution Approach 2:
The patent converts the harmful non-selective Ti deposition into a beneficial process by using the deposited Ti layers as temporary placeholders that are subsequently removed through thermal annealing or TiCl4 soaking. The initial non-selective deposition is transformed into a selective process through the follow-up treatment steps, eliminating the need for additional wet etching
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 cyclic method improves the selectivity of TiSi deposition on Si to SiN surfaces, minimizing the need for wet etch processes and enhancing the electrical characteristics of the TiSi layer.
Implementation Method 1
depositing a first layer including a metal by a plasma deposition process on a first surface and a second surface of a substrate
Implementation Method 2
heating the first layer to an annealing temperature and cyclically repeating the first layer deposition process and the heating the first layer process
Implementation Method 3
delivering a gas mixture including titanium tetrachloride (TiCl4) to the first surface and the second surface to remove at least a portion of the deposited metal on the second surface
Data Source
AI summary
Embodiments of the present principles generally relate to forming low resistivity contacts for semiconductor device formation. In some embodiments, a method of forming a metal silicide layer on a surface of a contact structure includes depositing a first layer including a metal on a first surface that includes silicon and a second surface that includes a dielectric material by providing a carrier gas, a metal-containing precursor, and a hydrogen-containing precursor to a deposition chamber and applying an RF power while maintaining the substrate at a first temperature. The method includes delivering a gas mixture including titanium tetrachloride (TiCl4) to the first surface and the second surface, while maintaining the substrate at the first temperature, to remove at least a portion of the deposited metal and cyclically repeating the metal deposition and the delivering the gas mixture processes to reach the desired thickness of the metal silicide layer.