Solid-State Image Sensor Divided Exposure Alignment
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Solution Overview
Problem
In the manufacturing of solid-state image sensors, misalignment during divided exposure can lead to variations in resist pattern sizes and device dimensions, affecting the performance and quality of the sensors, particularly due to errors in mask pattern design and exposure conditions.
Innovation Solution
The method involves positioning the dividing line for divided exposure over regions where active regions are defined on the semiconductor substrate, using a photoresist with partial active regions having step differences to facilitate accurate alignment and minimize dimensional changes in the element isolation structure, thereby reducing performance deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If divided exposure treatment is used to manufacture solid-state image sensors, then large-area semiconductor substrates can be processed, but misalignment between mask patterns occurs leading to resist pattern misalignment and device size variations
Solution Approach 1:
A mark formation layer is introduced as an intermediary between the photoresist and the semiconductor substrate. This layer contains alignment marks that serve as reference points for aligning mask patterns during divided exposure, enabling precise registration across multiple exposure regions without directly modifying the photoresist or substrate
Solution Approach 2:
The mark formation layer utilizes optical contrast (analogous to color change) to enable detection of alignment marks. The layer is formed with different refractive index or absorption characteristics than surrounding structures, allowing alignment marks to be clearly identified during inspection and alignment processes
2Area of stationary object
If divided exposure treatment is used, then large-area substrates can be manufactured, but variations in resist pattern size occur between adjacent exposure regions
Solution Approach 1:
The mark formation layer acts as an intermediary reference system that enables consistent dimensional control across divided exposure regions. By providing detectable alignment marks, it allows for precise positioning of each exposure region relative to others, ensuring uniform resist pattern sizes throughout the large substrate area
Solution Approach 2:
The alignment marks in the mark formation layer provide feedback information about the relative positions of exposure regions. This enables detection and correction of dimensional variations, ensuring consistent resist pattern sizes across the entire substrate by adjusting subsequent exposure positions based on mark alignment
3Manufacturing precision
If the position of the dividing line for divided exposure is not properly controlled, then misalignment of resist patterns occurs at dividing lines, but controlling the dividing line position adds complexity to the exposure process
Solution Approach 1:
The mark formation layer introduces alignment marks as intermediaries that simplify dividing line position control. Instead of directly controlling the abstract concept of dividing line position, the system uses tangible, detectable marks that automatically indicate where dividing lines should be positioned, reducing exposure process complexity while improving precision
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 approach allows for better grasp and control of the exposure dividing line, minimizing variations in resist patterns and device sizes, which enhances the electrical insulation properties and overall performance of the solid-state image sensors by reducing misalignment-induced issues.
Implementation Method 1
a photoresist is formed over a semiconductor substrate via a protective film. The photoresist is then exposed using a photomask.
Implementation Method 2
The photoresist thus exposed is then developed and patterned.
Implementation Method 3
The protective film exposed from the patterned photoresist is removed
Implementation Method 4
The semiconductor substrate exposed from the protective film is then oxidized and an element isolation structure is formed in the semiconductor substrate
Data Source
AI summary
There is provide a divided exposure technology capable of restraining deterioration in the performance of a solid-state image sensor. A photoresist is formed over a semiconductor substrate and subjected to divided exposure. A dividing line for divided exposure is located at least over a region of a semiconductor substrate in which an active region in which a pixel is to be formed is defined. The photoresist is then developed and patterned. By utilizing the patterned photoresist, an element isolation structure for defining the active region in the semiconductor substrate is formed in the semiconductor substrate.