The key challenge for enablement of a second node of single-expose EUV patterning is understanding and mitigating the patterning-related defects that narrow the process window. Typical in-line inspection techniques, such as broadband plasma and e-beam systems, find it difficult to detect the main yield-detracting defects postdevelop, and thus understanding the effects of process improvement strategies has become more challenging. New techniques and methodologies for detection of EUV lithography defects, along with judicious process partitioning, are required to develop process solutions that improve yield. This paper will first discuss alternative techniques and methodologies for detection of lithography-related defects, such as scumming and microbridging. These strategies will then be used to gain a better understanding of the effects of material property changes, process partitioning, and hardware improvements, ultimately correlating them directly with electrical yield detractors.
The key challenge for enablement of a 2nd node of single-expose EUV patterning is understanding and mitigating the patterning-related defects that narrow the process window. Typical in-line inspection techniques, such as broadband plasma (291x) and e-beam systems, find it difficult to detect the main yield-detracting defects post-develop, and thus understanding the effects of process improvement strategies has become more challenging. New techniques and methodologies for detection of EUV lithography defects, along with judicious process partitioning, are required to develop process solutions that improve yield.
This paper will first discuss alternative techniques and methodologies for detection of lithography-related defects, such as scumming and microbridging. These strategies will then be used to gain a better understanding of the effects of material property changes, process partitioning, and hardware improvements, ultimately correlating them directly with electrical yield detractors .
Extreme ultraviolet lithography (EUVL) is getting closer to practical use for mass production every year. For applying EUV lithography to manufacturing, productivity improvement is a critical challenge. Throughput and yield are important factors for productivity. EUV source power is steadily advancing year by year, bringing improvements in throughput. Furthermore, yield improvement is necessary for productivity enhancement. In order to improve the yield in EUV lithography processing, further improvement of defectivity and critical dimension (CD) uniformity is required. One of the initial layers to be printed with EUV will be contact hole, therefore, we are concentrating on the productivity improvements of that layer.
In our report at SPIE 2017, defect reduction was achieved using the latest rinse technology in the development process and in-film defectivity was improved with material dispense optimization on a 24 nm contact hole (CH) pattern. On the basis of the knowledge acquired from the previous evaluation, improvements have been taken a step further in this next evaluation. As a result, 96% of residue defect reduction and 42% of in -film particle defect reduction has been achieved by further rinse optimization and improvement of dispense system.
For the other aspect of yield improvement, CD uniformity control is one of the crucial factors. CD variations are comprised of several components such as wafer to wafer CD uniformity, field to field CD uniformity. To achieve CD uniformity target for manufacturing, we have optimized developing process with the latest technology. Then, 15% of field to field CD uniformity improvement and significant improvement of wafer to wafer CD uniformity are achieved.
Extreme ultraviolet lithography (EUVL) technology is getting closer to high volume manufacturing phase every year. In order to enhance the yield of EUV lithography processing, further improvement of defectivity and CD uniformity is required at the moment. In our previous report in 2017, we have exhibited the defectivity reduction by applying our new rinse and dispense system to a 24nm contact hole (CH) pattern. On the basis of the knowledge received through that evaluation, further study for improvement of the defectivity has been investigated in this paper. As a result of further optimization of the rinse process, 83 % further reduction of residue defect from the result reported previously is achieved. Also, CD uniformity control is a very crucial factor towards EUVL manufacturing phase. We have exposed 15 wafer batches continuously for both line/space and contact hole patterns in order to confirm the current status of wafer to wafer (WTW) as well as field to field (FTF), die to die (DTD), and local uniformity. Now further work for improving CD stability is ongoing based on the results from this first trial.
Extreme ultraviolet lithography (EUVL) technology is getting closer to high volume manufacturing phase every year. In order to enhance the yield in EUV lithography process, further improvement of defectivity is required at the moment. In this paper, optimized rinse and new dispense system (NDS) have been applied to a 24nm contact hole (CH) pattern in order to achieve defect reduction. As a result, the optimized rinse reduced approximately 70 % of residue defects. In addition, NDS for coating process exhibited 80 % defect reduction in particles in the coating films of material such as SOC, SOG, and resist.
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