Increasingly complex RET techniques need to be used in the sub wavelength regime
which will drive up the mask costs, as well as the design costs. Some of the RET
techniques used involves the use of OPC, PSM and hard mask. In order to reduce the
costs it is desirable to have uniform performance on shuttle masks, which can help to
reduce manufacturing costs. The micro loading and macro loading are of concern to mask
makers because of the varying loads being etched within the mask. It is critical to have a
mask etcher that provides excellent CD uniformity, CD bias, CD linearity and etch profile
in order to have image fidelity of the OPC structures as well as sustainable yields. This
paper discusses micro and macro loading challenges on BIM and APSM masks and the
advantages of using the Applied Materials' next generation mask etcher.
Increasingly complex RET techniques need to be used in the sub wavelength regime
which will drive up the mask costs, as well as the design costs. Some of the RET
techniques used involves the use of OPC, PSM and hard mask. In order to reduce the
costs it is desirable to have uniform performance on shuttle masks, which can help to
reduce manufacturing costs. The micro loading and macro loading are of concern to mask
makers because of the varying loads being etched within the mask. It is critical to have a
mask etcher that provides excellent CD uniformity, CD bias, CD linearity and etch profile
in order to have image fidelity of the OPC structures as well as sustainable yields. This
paper discusses micro and macro loading challenges on BIM and APSM masks and the
advantages of using the Applied Materials' next generation mask etcher.
Requirements to meet the 45nm technology node place significant challenges on Mask makers.
Resolution Enhancement Techniques (RET) employed to extend optical lithography in order to
resolve sub-resolution features, have burdened mask processes margins. Also, Yield compromises
loom with every nanometer of error incurred on the Mask and the Device platforms. RET techniques,
such as Optical Proximity Correction (OPC), require the Mask Etcher to achieve exceptionally tight
control of Critical Dimensions (CD). This ensures OPC feature integrity on the mask and resultant
image fidelity of OPC structures, as well as, subsequently high and sustainable yields.
This paper talks about 45 nm Chrome etch challenges and how Applied Materials next generation
mask etcher provides solutions to these challenges.
One means of extending the limits and lifetime of current lithography platforms for 45nm and
beyond is the development of resolution enhancement techniques (RET) in the form of optical
phase-shifting masks (PSM). By employing optical interference from 180° shifted lithography
emission, PSM masks are able to enhance feature resolution at the wafer. This is particularly
important for sub-wavelength features (i.e., features with critical dimensions less than the
lithography wavelength) where line resolution can be severely degraded without such techniques.
For these PSMs, the challenge is to provide highly uniform quartz etch performance across the entire
active area of the mask for various feature sizes and local loads. Micro-loading (a.k.a. RIE lag or
reactive ion etch lag) and phase angle range are key performance parameters to control. As the
demands for these parameters tighten and mask costs rise, strict performance control is required for
all PSM mask varieties utilized in the mask shop.
In this paper we will discuss process results using Applied Materials next generation mask etch
system in the area of APSM etch application. In particular, the discussion will focus on recent
process results in phase uniformity and RIE lag for Quartz etch process. Feature profiles are also
discussed with examples showing near vertical sidewalls and no micro-trenching.
KEYWORDS: Sensors, Etching, Data acquisition, Photomasks, Principal component analysis, Data mining, Statistical analysis, Interfaces, Zoom lenses, Process control
Mask Etching for the 45nm technology node and beyond requires a system-level data and diagnostics strategy. This necessity stems from the need to control the performance of the mask etcher to increasingly stringent and diverse requirements of the mask production environment.
Increasing mask costs and the capability to acquire and consolidate a wealth of data within the mask etch platform are primary motivators towards harnessing data mines for feedback into the mask etching optimization. There are offline and real-time possibilities and scenarios. Here, we discuss the data architecture, acquisition, and strategies of the Applied Materials Tetra IITM Mask Etch System.
Requirements to meet the 45nm technology node place significant challenges on Mask makers. Resolution Enhancement Techniques (RET) employed to extend optical lithography in order to resolve sub-resolution features, have burdened mask processes margins. Also, Yield compromises loom with every nanometer of error incurred on the Mask and the Device platforms. RET techniques, such as Optical Proximity Correction (OPC), require the Mask Etcher to achieve exceptionally tight control of Critical Dimensions (CD). This ensures OPC feature integrity on the mask and resultant image fidelity of OPC structures, as well as, subsequently high and sustainable yields.
This paper talks about 45 nm Chrome etch challenges and how Applied Materials Tetra IITM etcher provides solutions to these challenges.
One means of extending the limits and lifetime of current lithography platforms for 45nm and beyond is the development of resolution enhancement techniques (RET) in the form of optical phase-shifting masks (PSM). By employing optical interference from 180° shifted lithography emission, PSM masks are able to enhance feature resolution at the wafer. This is particularly important for sub-wavelength features (i.e., features with critical dimensions less than the lithography wavelength) where line resolution can be severely degraded without such techniques. For these PSMs, the challenge is to provide highly uniform quartz etch performance across the entire active area of the mask for various feature sizes and local loads. Micro-loading (a.k.a. RIE lag or reactive ion etch lag) and phase angle range are key performance parameters to control. As the demands for these parameters tighten and mask costs rise, strict performance control is required for all PSM mask varieties utilized in the mask shop. In this paper we will discuss process improvements for the Applied Materials Tetra IITM chromeless phase lithography (CPL) etch application. In particular, the discussion will focus on recent process improvements in phase uniformity and RIE lag for our chrome hard mask CPL etch process. Results from modifications to the etch process are presented. Feature profiles are also discussed with examples showing near vertical sidewalls and no micro-trenching.
Requirements to meet the 45nm technology node place many challenges on photomask makers. Resolution Enhancement Techniques (RET), employed to extend optical lithography in order to resolve sub-resolution features have burdened mask processes margins. Also, yield compromises rise with every nanometer of error incurred on the photomask (and device) platforms.
As photomask costs rise, strict performance control is required for all photomask varieties utilized in the mask shop. Mask etching for future technology nodes, requires a system-level data and diagnostics strategy. This necessity stems from the need to control the performance of the mask etcher at increasingly stringent and diverse requirements of the photomask production environment.
From etch applications perspective, alternating phase-shift masks (APSMs) and OPC masks pose key challenges. Specifically, the etcher needs to provide highly uniform CD performance across the entire active area of the photomask - for various feature sizes and load distributions, with no degradation to profiles. It is challenging to strike this balance, yet maintain adequate process window. Future etch systems require sensitive controls and knobs to provide this high precision and repeatable performance. Additionally, incoming variation in plate characteristics and quality necessitate tuning knobs capable of targeting the optimum performance across a diversity of applications.
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