MOM Capacitance Control via Dynamic Metal Layer Thickness Adjustment
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Solution Overview
Problem
In semiconductor technology, the CMP process for metal-oxide-metal (MOM) capacitors in sub-55 nm technology faces challenges in maintaining target capacitance values due to variations in metal layer thickness, leading to increased process costs and time, as well as deviations in capacitance measurements during wafer acceptance tests.
Innovation Solution
A method and system for dynamic regulation of metal layer thickness, where the thickness of each metal layer is measured, and updated target thicknesses are calculated for subsequent layers to minimize capacitance variations, using equations to determine optimal thickness adjustments and ensure the total thickness meets target values, thereby controlling MOM capacitance within the desired range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the subsequent metal layers are processed according to the original pre-set target thicknesses when the actual thickness of a previous metal layer offsets greatly from its target thickness, then the manufacturing process is simple and fast, but the total capacitance value of the MOM capacitor shifts from the target capacitance value
Solution Approach 1:
The patent implements a feedback mechanism where the actual thickness of each metal layer is measured after formation, and this measurement is fed back to dynamically adjust the target thickness of subsequent metal layers. The adjustment amount is calculated based on the thickness offset of previous layers to compensate for cumulative deviations and ensure the total capacitance value meets the target specification.
Solution Approach 2:
The patent transforms the static pre-set target thicknesses into dynamic adjustable parameters. The target thickness of each subsequent metal layer is no longer fixed but is determined dynamically based on the actual measurements of previous layers, allowing the system to adapt to process variations in real-time.
2Manufacturing precision
If the actual thickness of the copper layer is greater than the target thickness due to process variation, then rework of the CMP process is required to reduce the exceeded copper, but the process cost and process time are increased
Solution Approach 1:
The patent performs preliminary measurement of the metal layer thickness immediately after formation, before proceeding to subsequent processing steps. This early detection allows for dynamic adjustment of subsequent layer thicknesses to compensate for deviations, avoiding the need for rework CMP processes later in the manufacturing sequence.
Solution Approach 2:
The patent uses the target thickness adjustment of subsequent metal layers as an intermediary mechanism to compensate for thickness deviations. Instead of directly reworking the exceeded copper layer, the system adjusts the thickness of subsequent layers to achieve the desired total capacitance value, thereby avoiding additional CMP rework steps.
Data Source
AI summary
A method for MOM capacitance value control is disclosed. The method comprises: S01: setting a target thicknesses for each metal layers; S02: after forming a current metal layer, measuring a thickness of the current metal layer; when the thickness of the current metal layer is equal to or less than a threshold value, then turning to step S03; S03: calculating multiple capacitance variations related to the current metal layer according to the thickness of the current metal layer; wherein each of the capacitance variation related to the current metal layer is between an actual capacitance value of a MOM capacitor combination associated with the current metal layer and a target capacitance value of the same MOM capacitor combination; S04: calculating updated target thicknesses for all subsequent metal layers according to the capacitance variations related to the current metal layer.