Karl E. Mautz

Current state of 300-mm lithography in a pilot line environment

SEMICONDUCTOR300 (SC300) is the first pilot manufacturing facility for 300 mm wafers in the world. This company, a joint venture between Infineon Technologies and Motorola, is working on developing a 300 mm manufacturing tool set. The pilot line contains a full compliment of tools for 0.24 micrometer ground rule 64 M DRAM manufacturing. The 64 M DRAM was chosen for the ability to easily benchmark against 200 mm 64 M DRAM manufacturing data from the sister factory. Currently, testing on structures with less than 0.20 micrometer ground rules is occurring the pilot line. In this paper we present the performance of the initial lithography tool set installed at SC300. Several lots of wafers with measurable yield have been produced. These lots have produced data on overlay, critical dimensions, and run-to-run, wafer-to-wafer and within-wafer performance of the various lithography layers. We now have preliminary data on the comparison of 200 mm tools to 300 mm tools in terms of footprint, throughput, reliability, and productivity gains for equivalent square centimeters of silicon. With this data we can start to predict what performance we should expect from 300 mm manufacturing lithography tools.

Litho clusters with integrated metrology: the next step in continuous flow manufacturing

While integrated circuit manufacturing has demonstrated continuous productivity improvement over the last twenty years (as driven by Moores Law), there remain significant areas for improvement. The lithographic tools in current factories have set the example in productivity improvement. They have evolved from individual tools for vapor prime, coat, expose, bake operations to integrated exposure tools and photoresist tracks that handle wafers sequentially from a load port until they return to the same load port. This paper examines the next logical step in this evolution resulting in the formation of a lithography (Litho) cluster by adding metrology for critical dimension (CD) and overlay measurements and optical inspection. Since with sampling of selected sites and wafers, CD and overlay measurements are relatively quick processes, one or more lithography photocells (exposure tool and photoresist track combinations) could be integrated to one set of centrally located metrology tools. Alternatively, simpler and smaller metrology modules could be integrated into each Litho cluster tool. Since the load ports and robotics could be shared and the total number of metrology tools in the factory is expected to increase dramatically, cost reduction and economies of scale in this combination of tools may be achieved. The benefits are estimated to be a 20% improvement in cycle time and simplified material handling.

Maturity assessment of 300-mm etch equipment

Oxide and dielectric etch, polysilicon etch, and metal etch, in situ strip and stand-alone ash processes for 300mm wafers were developed on a tool ste in SEMICONDUCTOR300 and tested for robustness using a 0.25(mu) 64Mb DRAM device. The process recipes were developed from reference scaled-up recipes. The oxide and dielectric etch tools used magnetically-enhanced reactive ion etching. They polysilicon etch tool chambers were high density plasma configurations. The metal etch tools used high-density plasma chambers and have an in-line resist strip module to prevent corrosion. Stand-alone ash tools were used for all other photoresist strip processes. For each application, at least two 300mm tools from different suppliers were tested. This paper discusses process and tool interactions affecting operational robustness and stability. Process and hardware evaluations were also done during extensibility testing using smaller linewidth features.

GOI characterization of 300-mm furnace tools

The purpose of this characterization was to gain an initial understand of the gate oxide integrity (GOI) differences on wafers processed in the 300mm furnace tools at SC300, a joint venture between Motorola and Infineon Technologies for 300mm wafer, process and equipment development, compared to similarly processed 200mm wafers at Motorola. Measurements were done using mercury probe tools located at different sites to characterize the various gate oxide films and thicknesses. Separately, a study was done on defectivity levels of the Epi-layered 300mm wafers used in this study.

Microloading characterization of 300-mm etch and CMP tools

An investigation of the microloading effects form the 300mm wafer Etch and CMP polish processes was done at SC300, a joint venture between Motorola and Infineon Technologies for 300mm wafer, process and equipment development in Dresden, Germany. Test wafers were constructed to approximate the structural features of DRAM and microprocessors devices, and standard or scaled-up processes were run to identify potential limitations and defects. Oxide dielectric etch and CMP process instability and microloading effects are know n to cause significant device yield loss.

Progress on 300-mm wafer lithography equipment and processes

SEMICONDUCTOR300 was the first pilot-production facility for 300mm wafers in the world. The company, a joint venture between Motorola, Inc. and Infineon Technologies started in early 1998 to test and compare process, metrology and probe equipment, develop robust processes, and manufacture products using a 300mm wafer tool set. The lithography tools included I-line steppers, an I-line scanner, a DUV stepper, and DUV scanners. All of these exposure tools were running in-line with various photoresist coat and develop tracks. The lithography tools were used to build both 64M and 256M DRAM devices and aggressive test vehicles. The process capability of the initial 0.25 micrometers reference process was done and compared to the 200mm data set of the sister factory. Automation issues for lithography tools were addressed and the cost metrics were calculated. SC300 demonstrated that a manufacturable 300mm lithography tool set and process for various ground rule devices was possible with the required performance in image transfer, CD control, and overlay. Further testing on 0.18micrometers and 0.15micrometers ground rule features indicated a sufficient process window for potential manufacturing. Additionally, it was demonstrated that non-concentric subfield stepping was feasible.

Evaluation techniques for 300-mm equipment

As the semiconductor industry begins its transition to its next wafer size threshold of 300mm, several key factors are becoming significant. Solving the problems surrounding these factors is critical to achieving a 30-40 percent cost savings over 200mm wafer integrated circuit manufacturing. These problematic areas involve automation, equipment readiness, and process performance. 300mm factories will differ from 200mm versions due to the automation level, lot size choices, and factory sizing targets in terms of wafer starts. This paper discusses these areas from data acquired at SEMICONDUCTOR300 in processing a 0.25 micrometers 64Mb DRAM device. Current performance is discussed for each semiconductor manufacturing tool functional group. These data include performance cost of ownership, on automation and computer integrated manufacturing, and process capability.

Process performance comparisons on 300-mm i-line steppers, DUV stepper, and DUV scanners

SEMICONDUCTOR300 was the first pilot production facility for 300mm wafers in the world. This company, a joint venture between Infineon Technologies and Motorola, is working to develop a manufacturable 300mm wafer tool set. The lithography tools include I-line steppers, a DUV stepper, and two DUV scanners. These tools are used to build 64M DRAM devices and aggressive test vehicles. Data will be presented on the mix-and-matching performance between DUV scanners and I-line steppers. Process-related data on CD within-field and across wafer sampling for selected tool types were investigated. The process capability of the current tool set for 0.25 micrometers and 0.18 micrometers devices were compared. Resolution performance of the scanner with its 0.68 numerical aperture was studied. Dense and isolated printed pattern performance was measured with in-line metrology. 300mm wafers are sensitive to backside defectivity, and therefore the wafer chuck design plays an important role in achieving the desired pattern transfer performance. The performance of the different chuck types and their sensitivity to incoming backside wafer contamination levels was studied. Rework data was used to assist in characterizing the exposure dose matching and chuck type performance.

Effect of nonlinear errors on 300-mm wafer overlay performance

SEMICONDUCTOR3000 was the first pilot production facility for 300nm wafers in the world. This company, a joint venture between Infineon Technologies and Motorola, is working to develop a manufacturable 300mm wafer tool set. The lithography tools include I-line stepper, and two DUV scanners. These tools are used to build both 64M DRAM devices and aggressive test vehicles. This paper shows the influence of non-linear errors on 300nm wafers is much stronger than on 200mm wafers. The team determined the root causes for the stronger appearance of these effects and proposed solutions to improve the overlay performance.

Is lithography ready for 300 mm

SEMICONDUCTOR300 was the first pilot production facility for 300mm wafers in the world. This company, a joint venture between Infineon Technologies Motorola, started in early 1998 to develop processes and manufacture products using 300mm wafer tool set. The lithography tools include I-line steppers, as I-line scanner, a DUV stepper, and DUV scanners. All of these exposure tools are running in-line with a photoresist coat and develop track. The lithography tools are used to build 64Mb DRAM devices and aggressive test vehicles with design rules of 0.25 micrometers and below, in sufficient quantity to be able to assess the tool readiness. This paper present the history of technical improvements and roadblocks that have occurred on the 300mm lithography tool set since the start-up, and describe a methodology used to assess the tool performance.