Curved Display Substrate Thickness Control

The patent applies local quality by creating different thickness regions (first, second, and third thickness regions) with specific etching depths in different areas of the substrate. The protruding region has a different thickness profile compared to other regions, with controlled etching that maintains structural integrity while achieving the desired curved shape. This localized thickness control prevents stress concentration and cracking in critical areas.

The substrate is divided into multiple thickness regions with different etching depths. The first thickness region has a first etching depth, the second thickness region has a second etching depth, and the third thickness region has a third etching depth. This segmentation allows different parts of the substrate to have optimized thickness profiles, reducing overall thickness deviation while maintaining the curved shape.

The patent implements local quality control by applying different etching depths to different regions. The protruding region maintains adequate thickness (first thickness region with first etching depth) to prevent cracking, while other regions can be more aggressively thinned. This localized approach reduces overall device thickness without compromising the structural integrity of stress-prone areas.

The patent applies beforehand cushioning by designing the thickness profile in advance to prevent future stress concentration. The controlled etching patterns create a gradual thickness transition and maintain minimum thickness thresholds in protruding regions before bending, cushioning against potential cracks that would otherwise occur during or after the bending process.

The etching process is segmented into multiple steps with different masking patterns. First masking defines the first etching depth region, second masking defines the second etching depth region, and third masking defines the third etching depth region. This segmentation transforms a complex single-step asymmetric etch into multiple simpler, more controllable steps, reducing process complexity while achieving the desired curved profile.

The patent applies preliminary action by performing sequential etching steps where each masking step prepares the substrate for the next etching operation. The first masking and etching step creates a preliminary thickness profile, which is then further refined by subsequent masking and etching steps. This preliminary action approach simplifies the overall process by breaking down the complex asymmetric shaping into manageable stages.