Apparatus and Method for the Minimization of Undercut During a UBM Etch Process

A system for endpoint detection in a wet etching process of a substrate, the system comprising:

• a light source configured to emit light onto a plurality of sample locations on a surface of a first substrate during the wet etching process of the first substrate;
• a light detector configured to detect reflection of the light that is emitted onto each of the plurality of sample locations of the first substrate during the wet etching process of the first substrate;
• at least one processor configured to execute instructions stored on processor readable media, wherein the processor, when executing the instructions, is further configured to:
• analyze first light information associated with the light reflected from each of the plurality of sample locations of the first substrate to represent the first light information in a first color model, wherein the at least one processor represents the first light information in the first color model by assigning a red color value, a green color value and a blue color value for each of the plurality of sample locations;
• convert the representation of the first light information from the first color model to a second color model as a function of a non-linear transformation, by assigning respective values for hue, saturation, and brightness;
• determine an end point of the wet etching of the first substrate using the light information represented by the second color model associated with at least one of the sample locations of the first substrate;
• and
• generate etch parameters for a wet etching process for a second substrate based on the analyzed first light information represented by the second color model;
• wherein the light source is further configured to emit light onto at least a plurality of sample locations on the surface of the second substrate during the wet etching process of the second substrate;
• further wherein the light detector is further configured to detect a reflection of light off the plurality of sample locations on the surface of the second substrate during the wet etching process of the second substrate;
• and
• further wherein the at least one processor, when executing the instructions is further configured to:
• analyze second light information associated with the light reflected from each of the plurality of sample locations of the second substrate, to represent the second light information in the first color model for each of the plurality of sample locations of the second substrate;
• convert the representation of the second light information from the first color model to the second color model as a function of a non-linear transformation, by assigning respective values for hue, saturation, and brightness;
• apply the representation of at least some of the second light information represented by the second color model and the generated etch parameters to determine an end point of the etching of the second substrate;
• and
• modify, during the wet etching process of the second substrate, the generated etch parameters based on the representation of the at least some of the second light information represented by the second color model and the generated etch parameters to determine an end point of the etching of the second substrate.

A method for determining a plurality of endpoints in a wet etching process of a substrate, the method comprising:

• determining, by at least one processor configured by executing instructions, a plurality of benchmark end points during a wet etching process of a first substrate, the plurality of benchmark end points determined by using first light information represented by a Hue, Saturation, Value color model associated with a plurality of sample locations of the first substrate;
• generating, by the at least one processor, etch parameters for a wet etching process for a second substrate based on the determined benchmark end points;
• and
• using, by the at least one processor during the wet etching process of the second substrate, the generated etch parameters and second light information represented by at least one value of the Hue, Saturation, Value color model associated with a plurality of sample locations of the second substrate to reach respective end points during the wet etching process of a second substrate.