Thin Film Resistor Plug Structure for Low-Resistance CMP Contacts
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Solution Overview
Problem
The formation of a 'step' between the upper surface of a dielectric layer and the polished surface of a tungsten plug electrode during CMP results in reduced plug electrode diameter, increasing contact resistance with the thin film resistor, and the use of buff polishing to address this issue increases manufacturing costs.
Innovation Solution
A semiconductor device with a plug electrode comprising a barrier layer and a buried layer, including a filling portion and an extension portion, where the second incline angle of the extension portion is smaller than the first incline angle, reducing contact resistance and preventing disconnection of the thin film resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If buff polishing is performed to eliminate the step, then the polished surfaces of the dielectric layer and tungsten film become substantially uniform, but the manufacturing cost increases
Solution Approach 1:
The patent extracts the problematic buff polishing step from the manufacturing process by using an alternative approach. Instead of performing buff polishing to eliminate steps, the invention uses a barrier layer that prevents step formation during standard CMP, thereby eliminating the need for the additional costly buff polishing operation while maintaining surface uniformity.
2Manufacturing precision
If the plug electrode diameter is reduced due to step formation, then the contact area with the thin film resistor is reduced, but the contact resistance increases
Solution Approach 1:
The barrier layer is formed in advance before CMP processing to prevent step formation that would reduce the plug electrode diameter. This preliminary protective layer ensures that the plug electrode maintains its full diameter and adequate contact area with the thin film resistor, thereby preventing increased contact resistance.
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 solution effectively reduces contact resistance between the thin film resistor and the plug electrode while maintaining low manufacturing costs by using a CMP method without buff polishing, allowing for a more reliable and cost-effective manufacturing process.
Implementation Method 1
The plug electrode is formed by filling an opening formed in a dielectric layer with a tungsten film and then selectively leaving the tungsten film only in the opening by a CMP (Chemical Mechanical Polishing) method
Implementation Method 2
performing a sputter etching treatment to the filling portion, thereby forming an extension portion extending from the filling portion on the barrier layer along the second incline surface
Data Source
AI summary
A semiconductor device includes a wiring layer, a dielectric layer covering the wiring layer, a thin film resistor provided on the dielectric layer, and a plug electrode connecting the thin film resistor to the wiring layer. The plug electrode includes a barrier layer and a buried layer. The buried layer is configured by the filling portion filling a region surrounded by a first incline surface, and an extension portion extending from the filling portion along a second incline surface. The thin film resistor is in contact with the filling portion and the extension portion of the plug electrode. A second incline angle between the second incline surface and a main surface of a semiconductor substrate is smaller than a first incline angle between the first incline surface and the main surface of the semiconductor substrate.