Semiconductor Memory Borderless Contact Formation via Double Exposure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor memory technologies face challenges in forming non-uniform patterns in extended regions due to miniaturization, which limits the formation of contacts and interconnects at fine pitches, making it difficult to achieve regular line and space patterns.
Innovation Solution
The semiconductor memory employs a contact formation method using double exposure to create borderless contacts that cover part of the interconnects, allowing for improved yield by forming bit line contacts, source line contacts, and via contacts in contact connecting regions at a cell rule-based pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If double exposure is used to form patterns with high resolution in a single direction, then cell miniaturization is achieved, but non-uniform patterns cannot be formed in the extended region
Solution Approach 1:
The extended region is divided into multiple exposure regions (first exposure region and second exposure region) with different pitch requirements. The first exposure region uses a first pitch for cell patterns, while the second exposure region uses a second pitch for contact patterns, allowing each region to be optimized independently
Solution Approach 2:
Different pitch specifications are applied to different regions: the first exposure region maintains cell rule-based pitch for high-resolution cell patterns, while the second exposure region uses relaxed pitch for contact formation, allowing each region to have the quality appropriate for its function
2Ease of manufacture
If contacts are formed within regular line and space patterns, then manufacturing consistency is maintained, but contact formation becomes difficult in extended regions
Solution Approach 1:
The exposure process is segmented into two distinct exposures: first exposure for cell patterns with cell rule pitch, and second exposure for contact patterns with relaxed pitch. This allows contact formation in the extended region without being constrained by the regular cell pattern requirements
Solution Approach 2:
The solution adds a temporal dimension by using sequential exposures rather than attempting to form all patterns simultaneously. The second exposure is applied specifically to the extended region after the first exposure, allowing contact patterns to be formed in a different dimensional context (different pitch requirements)
Data Source
AI summary
Borderless contacts for word lines or via contacts for bit lines are formed using interconnect patterns, a part of which is removed. A semiconductor memory includes: a plurality of active regions AAi, AAi+1, . . . , AAn, which extend on a memory cell array along the column length; a plurality of word line patterns WL1, WL2, . . . , extend along the row length and are non-uniformly arranged; a plurality of select gate line patterns SG1, SG2, . . . , are arranged parallel to the plurality of word line patterns; borderless contacts are formed near the ends of the word line patterns on the memory cell array, and are in contact with part of an interconnect extended from the end of the memory cell array, but are not in contact with interconnects adjacent to that interconnect; and bit line contacts are formed within contact forming regions provided by removing part of the plurality of word line patterns and select gate line patterns through double exposure.