Tungsten Film Uniformity and Adhesion via Reducing Agent Pulses
Solution Overview
Problem
Conventional tungsten deposition processes struggle to produce thin films with low electrical resistivity and uniformity, while maintaining good adhesion, especially as wafer sizes increase and technology advances require thinner connections.
Innovation Solution
Exposing the tungsten nucleation layer to multiple sequential pulses of a reducing agent, such as diborane, before depositing the tungsten bulk layer, which improves the resistivity, uniformity, and adhesion of the tungsten film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional tungsten deposition process is used, then tungsten bulk layer can be deposited rapidly, but the film cannot be produced easily and reliably without first forming a nucleation layer
Solution Approach 1:
The patent applies preliminary action by depositing a thin nucleation layer of tungsten before the bulk layer deposition. This nucleation layer serves as a foundation that enables reliable and rapid subsequent deposition of the tungsten bulk layer, solving the problem of producing thin films with low resistivity and good uniformity.
2Length of moving object
If tungsten film thickness is reduced to meet advancing technology requirements, then thinner electrical connections are achieved, but maintaining very low resistivity becomes more difficult
Solution Approach 1:
The patent applies local quality by creating a nucleation layer with specific properties (low resistivity and good uniformity) that is different from the bulk layer. This localized treatment of the thin film region ensures that even at reduced thickness, the film maintains very low resistivity and excellent electrical connection properties.
3Productivity
If wafer size is increased to improve production capacity, then more devices per wafer are achieved, but uniformity of film properties across the wafer becomes more critical and difficult to maintain
Solution Approach 1:
The patent applies preliminary action by forming a uniform nucleation layer across the entire wafer surface before bulk deposition. This preliminary uniform layer ensures that subsequent bulk layer deposition maintains excellent uniformity across large wafer areas, enabling increased devices per wafer while preserving film property consistency.
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 results in tungsten films with low resistivity, excellent sheet resistance uniformity, and good adhesion, as demonstrated by reduced resistivity and non-uniformity percentages, and maintained adhesion, even with thinner film thicknesses.
Implementation Method 1
exposing the tungsten nucleation layer to a reducing agent before depositing the tungsten bulk layer
Implementation Method 2
The deposition of tungsten films using chemical vapor deposition (CVD) techniques
Data Source
AI summary
Methods of improving the uniformity and adhesion of low resistivity tungsten films are provided. Low resistivity tungsten films are formed by exposing the tungsten nucleation layer to a reducing agent in a series of pulses before depositing the tungsten bulk layer. According to various embodiments, the methods involve reducing agent pulses with different flow rates, different pulse times and different interval times.