Color Filter Spin Coating Trench Filling Striation Prevention
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Solution Overview
Problem
The striation effect in color filter layers, caused by trenches in the peripheral region of a substrate, degrades display performance by extending into the display region and potentially damaging metal pads during the formation of color filter layers.
Innovation Solution
A method involving multiple spin-on coating processes with varying spin rates to form and pattern color filter layers, where the first layer fills trenches, and subsequent layers are formed with specific thicknesses and spin rates to prevent striation and protect metal pads, ensuring even layer formation and patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single spin-on coating process is used to form color filter layers, then the process is simple and fast, but the striation effect occurs due to trenches in the peripheral region
Solution Approach 1:
The coating process is divided into multiple sequential spin-on coating steps, where each step deposits a color filter layer with specific thickness control. The first color filter layer is formed to fill trenches, followed by additional layers to achieve uniform total thickness, thereby eliminating striation while maintaining process efficiency
Solution Approach 2:
The first color filter layer is specifically designed to fill the trenches in the peripheral region before subsequent layers are deposited. This preliminary filling action prevents the striation effect from propagating into the display region, as later layers are deposited on a flattened surface
2Device complexity
If color filter layers are formed without filling trenches first, then the process is simpler, but the striation effect extends from peripheral trenches into the display region
Solution Approach 1:
The first color filter layer is deposited with sufficient thickness to completely fill the trenches in the peripheral region. This preliminary filling creates a flat surface for subsequent layers, preventing striation propagation into the display region while maintaining overall process simplicity
Solution Approach 2:
The first color filter layer serves a dual function: it provides the color filter function in the display region while simultaneously filling the trenches in the peripheral region. This local differentiation in function within the same layer resolves the contradiction between process simplicity and layer uniformity
3Ease of operation
If trenches are present in the passivation layer, then die seal ring or metal pad exposure is achieved, but the step high of trenches causes striation in color filter layers
Solution Approach 1:
The first color filter layer is deposited to fill the trenches before subsequent color filter layers are formed. This preliminary filling action eliminates the step high effect that causes striation, while the trenches remain functional for die seal ring or metal pad exposure
Solution Approach 2:
The first color filter layer acts as a counter-action to the harmful step high effect by filling the trenches and creating a flat surface. This preliminary anti-action prevents the striation effect from occurring in subsequent layers while preserving the functional trenches
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
Effectively prevents striation effects in the display region, enhances display performance, and protects metal pads from damage during color filter layer formation.
Implementation Method 1
forming a first color filter layer over the passivation layer to fill the trench by performing a first spin-on coating process with a first spin rate
Data Source
AI summary
A method for forming a color filter is provided. A substrate having a passivation layer thereon is provided. The passivation layer has at least one trench therein within a peripheral region of the substrate. A first color filter layer is formed over the passivation layer to fill the trench by performing a first spin-on coating process with a first spin rate. Thereafter, the first color filter layer is patterned so as to form a plurality of first color filter blocks in a display region of the substrate and expose a portion of the passivation layer. A second color filter layer is formed over the passivation layer by performing a second spin-on coating process with a second spin rate, which is larger than the first spin rate. Next, the second color filter layer is patterned to form a plurality of second color filter blocks between the first color filter blocks respectively.