Alain Charles

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.

Performance of 300-mm lithography tools in a pilot production line

Semiconductor 300 is the first pilot manufacturing facility for 300mm wafers in the world. This company is a joint venture between Siemens and Motorola, formed for the purpose of developing a 300mm manufacturing tool set. The pilot line contains a full compliment of tools for DRAM manufacturing. This paper discusses the performance of the initial 300mm lithography tool set installed in our pilot line in Dresden, Germany. The product used for evaluating and debugging the tool set is a 0.25-micron ground rule 64 Meg DRAM. This was chosen for the ability to easily benchmark against 200mm DRAM manufacturing data. We have produced several lots of wafers with measurable yield. These lots have produced data on overlay, CD and run to run performance of the lithography tools on actual product. We have data on resist coating, and develop uniformity. With several lithography tools installed we have generated a large amount of mix and match data. In addition several challenges for successful lithography have surfaced related entirely to the increase in wafer size. Film, etch, polish and thermal non-uniformity have impacted the throughput and performance of the lithography tools. The installation of the first integrated 300mm pilot line has also produced data on the impact larger wafer size has on tool logistics, for example fab layout, installation schedules and wafer and lot transport. While technical data is always important, the main reason for converting to 300mm is economic. We now have preliminary data on the comparison of 200 tools to 300mm tools in terms of footprint, throughput, and productivity gains for equivalent square centimeters of silicon. With this data we can start to make preliminary recommendations for 300mm manufacturing tools.

Photolithography equipment control through D-optimal design

In a large manufacturing environment, one of the process engineers tasks is to ensure that all the equipment and its associated processes are well under control. This is usually achieved by running a daily monitor test on each single piece of equipment. Unfortunately, this leads to a large number of test wafer usages and becomes very time consuming if an out of control situation is detected. Things get even more complicated when the overall process is done by adding several individual processes, since the result of the test on one equipment depends on how well another one did perform. In such case, false alarms might happen and the wrong process or equipment shut down. Therefore, a need for a more reliable method must be proposed. This paper intends to describe one possible solution, and the first results of its implementation in the photolithography area.

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.