Dual-Step Etching for Uniform Connection Hole Depth

The single etching process is divided into two sequential etching processes. The first etching process uses a first etching gas to etch the interlayer dielectric layer, and the second etching process uses a second etching gas to continue etching. This segmentation allows each process to be optimized for different hole size ranges, achieving both high productivity and consistent etching depth across connection holes of different diameters.

The patent changes the etching gas parameters between the two etching processes. The first etching gas and second etching gas have different compositions and properties, which results in different etching rates for holes of different sizes. By adjusting gas flow rates, pressure, and composition, the patent achieves complementary etching behavior where larger holes are etched faster in the first process and smaller holes are etched more effectively in the second process.

The etching process is segmented into two stages with different termination criteria. The first etching process stops when the etching depth reaches a first threshold value that prevents the etching stopper layer from being exposed in larger holes. The second etching process then continues etching to a second threshold value, allowing smaller holes to reach the stopper layer while larger holes stop before damage occurs. This segmentation enables uniform etching depth without excessive damage.

The patent applies partial etching in the first process and completes the etching in the second process. The first etching process performs partial etching to a depth that is sufficient for smaller holes but intentionally stops before larger holes would damage the stopper layer. The second etching process then performs the remaining etching needed to achieve uniform final depth, applying excessive action only where needed (in smaller holes) while avoiding it in larger holes.

The patent segments the etching process into two distinct stages with different stopping criteria. The first etching process stops when a first threshold depth is reached, protecting the etching stopper layer from exposure in larger holes. The second etching process then continues etching to a second threshold depth, allowing smaller holes to reach the required depth while larger holes remain protected. This segmentation resolves the contradiction between protection and uniformity.

The patent uses periodic action by alternating between two etching processes with different gas compositions and parameters. The first periodic action (first etching process) etches to a depth that protects the stopper layer, then the second periodic action (second etching process) continues etching to achieve final uniform depth. This periodic alternation allows the system to switch between protective mode and completion mode, achieving both stopper layer protection and uniform etching depth.