Bit Line Alignment Control for Uniform Memory Cell Contact Windows
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Solution Overview
Problem
The lithography technology in semiconductor manufacturing often results in imprecise alignment and control of critical circuit dimensions, leading to uneven contact window areas in memory cells sharing an active region, which affects product yield.
Innovation Solution
A method and system for monitoring and controlling semiconductor processes by forming active regions, detecting and measuring positions and dimensions, calculating estimated contact window areas, and adjusting the predefined position of bit lines to ensure uniform contact window areas through multiple iterations of patterned photoresist layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography technology is used to define word lines and bit lines, then the manufacturing process is simple and fast, but the alignment precision and contact window area uniformity deteriorate
Solution Approach 1:
The patent performs preliminary measurement of the first patterned photoresist layer (word lines) before forming the second patterned photoresist layer (bit lines). Based on the measured positions and dimensions, the system calculates and determines the optimal position of bit lines in advance, then applies offset compensation to ensure uniform contact window areas. This preliminary action prevents alignment errors from affecting contact window uniformity.
Solution Approach 2:
The patent implements a feedback mechanism where the actual positions and dimensions of the first patterned photoresist layer are measured, and this measurement information is fed back to adjust the position of the second patterned photoresist layer. The system calculates the offset between the measured position and the predefined position, then compensates for this offset when forming the bit lines, creating a closed-loop control system that improves alignment precision.
2Productivity
If the predefined position of bit lines is not adjusted, then the manufacturing process is fast and simple, but the contact window areas become uneven affecting product yield
Solution Approach 1:
The patent replaces the traditional mechanical/physical alignment method with an automated measurement and calculation system. Instead of relying solely on lithography equipment alignment mechanisms, the system uses measurement devices to detect the actual positions, calculates the required offsets, and automatically adjusts the bit line positions through software control, thereby improving both precision and efficiency.
3Manufacturing precision
If measurement and adjustment steps are added to the lithography process, then the contact window uniformity improves, but the manufacturing time and process complexity increase
Solution Approach 1:
The patent changes the positional parameters of the second patterned photoresist layer based on measured data from the first layer. By calculating the offset between the measured position and the predefined position, the system adjusts key parameters (position coordinates) to compensate for lithography errors, thereby improving alignment precision without requiring fundamental process changes.
Data Source
AI summary
A method and system for monitoring and controlling a semiconductor process are provided. The method includes: forming at least one active region on a substrate; forming a first patterned photoresist layer for defining at least two word lines on the active region after forming the active region; detecting and measuring positions and dimensions of the active region and the first patterned photoresist layer and calculating estimated areas of at least two estimated contact windows in the active region according to a predefined position of at least one bit line; adjusting the predefined position of the at least one bit line according to the estimated areas of the at least two estimated contact windows in the active region; and forming a second patterned photoresist layer on the substrate. The second patterned photoresist layer corresponds to the adjusted predefined position of the at least one bit line.