Problems In The Etching Process

0040-02544 Upper Body, Dps Metal

0020-33806 Upper Chamber Dps + Poly

 

 

Problems in the Etching Process

This article describes the problems in the etching process.

Etching is one of the key steps in the semiconductor manufacturing process and is used to remove a specific material from a wafer to form a circuit pattern. However, during dry etching, engineers often encounter issues such as loading, micro-trenching, and charging effects, which can directly affect the quality and performance of the final product.

 

Loading Effect

The loading effect refers to the phenomenon that the etching rate decreases or the etching is uneven due to the insufficient supply of reactive plasma during the dry etching process when the etching area increases or the etching depth increases. This effect is usually related to the characteristics of the etching system, such as plasma density and uniformity, vacuum, etc., and is widely present in various reactive ion etching.

Improve plasma density and uniformity: Generate higher density, more uniformly distributed plasma by optimizing the design of the plasma source, such as using more efficient RF power supplies or magnetron sputtering.

Adjust the composition of the reaction gas: Adding the right amount of auxiliary gas to the reaction gas can improve the homogeneity of the plasma and promote the efficient discharge of etching by-products.

Optimize the vacuum system: Increasing the pumping speed and efficiency of the vacuum pump helps to reduce the residence time of etching by-products in the chamber, which in turn reduces the loading effect.

Reasonable lithography layout: When designing lithography layout, the density of the pattern should be taken into account, and the over-dense arrangement of local areas should be avoided to reduce the impact of loading effect.

 

Trenching Effect

The micro-groove effect refers to the non-vertical chamfering of the sidewall due to the high-energy particles hitting the etching surface at an oblique angle during the etching process, so that the etching rate near the sidewall is higher than that in the center area. This phenomenon is closely related to the angle of the incident particle and the slope of the sidewall.

Increase RF power: Increasing the RF power appropriately can increase the energy of the incident particles, making them bombard the target surface more vertically, thereby reducing the difference in etching rate of the sidewall.

Choose the right etching mask material: Some materials are better able to resist charging effects and reduce the micro-trenching effect that is exacerbated by the accumulation of negative charge in the mask.

Optimization of etching conditions: The selectivity and uniformity of etching can be effectively controlled by finely adjusting the temperature, pressure and other parameters during the etching process.

 

Charging Effect

The charging effect is caused by the insulating properties of the etching mask, when the electrons in the plasma cannot escape quickly, they will accumulate on the surface of the mask, forming a local electric field, interfering with the path of the incident particles, affecting the anisotropy of the etching, especially when etching small structures.

Choose the appropriate etching mask material: Some specially treated materials or conductive mask layers can effectively reduce the accumulation of electrons. Implement intermittent etching: By periodically interrupting the etching process and giving the electrons enough time to escape, the charging effect can be significantly mitigated.
Adjust the etching environment: Changing the gas composition, pressure, and other conditions in the etching environment can help improve the stability of the plasma and reduce the occurrence of charging Effects

.