DISCO Corporation (Head Office: Ota-ku in Tokyo; President: Kazuma Sekiya), a semiconductor manufacturing equipment manufacturer, has developed "MUSUBI", a cluster system^*1 featuring efficient wafer transfer and reduced wafer breakage risk, accomplished by connecting multiple equipment units as necessary for the manufacturing process. DISCO has also developed DMG8762 (grinder/polisher), DME8061 (dry etcher), and DMM9200 (wafer mounter), which are compatible with this cluster system. These three equipment models will be connected through MUSUBI and displayed at SEMICON Japan 2019 (December 11 to 13, Tokyo Big Sight).

*1 Cluster system: An equipment configuration adopted mainly for front-end processes in semiconductor manufacturing. A cluster system has multiple process chambers and unloads wafers to the cassette after completing all processes, rather than after each process. Based on this concept, this cluster system, named “MUSUBI,” has been developed for and applied to back-end processes.

Development Background

In recent years, the need for greater cloud server capacity has increased in response to the spread of mobile devices, leading to an increase in demand for NAND flash memory and DRAM. Stacking thin die is the main method for increasing memory capacity, and at manufacturing sites, a variety of manufacturing processes, including DBG^*2 and SDBG^*3, have been adopted in addition to the conventional process, which singulates wafers into die after backgrinding. Further demand for thinning is expected to increase as 5G and IoT evolve. In addition, there has been an increase in demand for flexibility in various processes and for improvement in productivity. To respond to this demand, DISCO has developed a cluster system with a new transfer system—"MUSUBI."

*2 DBG: Dicing Before Grinding, which is a processing method that first half-cuts a wafer and then separates the wafer into die during backgrinding
*3 SDBG: Stealth Dicing Before Grinding, which is a processing method that first performs stealth dicing, which forms an SD layer in a wafer by focusing the laser inside the wafer, and then separates the die during backgrinding.

Features of Cluster System "MUSUBI"

• High flexibility
  The system can connect multiple units and different types of equipment to a shared transfer section, making it possible to achieve flexible equipment configurations as necessary for the manufacturing process (figure 1). In addition, equipment manufactured by companies other than DISCO can also be connected with MUSUBI as long as they are compatible.

  

• Reduced wafer breakage risk
  Previously, an operator would remove the cassette containing processed wafers and carry it to another unit for the subsequent process. With MUSUBI, the hand robot transfers the wafers one by one between equipment and stores them in the cassette after processing, reducing the risk of wafer breakage (figure 2).

  

• Optimized transfer hand robot configuration and high throughput
  The transfer hand robot loads and unloads wafers from each unit while traveling along the lane between equipment. A system to prevent wafers from being idle due to transfer can be established by adding an optimized number of robots as determined based on the equipment processing time (figure 3).
  

  

  Additionally, a “double-hand robot” has also been introduced. The double-hand robot integrates the full wafer suction pad used to transfer thinned wafers and the mechanism used to transfer wafers mounted to a dicing frame, making this robot able to support various processes (figure 4).
  

  

Features of MUSUBI-Compatible Equipment

Grinder/Polisher DMG8762

• Enhanced processing accuracy
  The impact on accuracy due to temperature changes around the processing table can be reduced by adding and optimizing a cooling mechanism around the chuck table that retains wafers, achieving high accuracy grinding and polishing with a total thickness variation of 1.5 µm or less (when using DISCO’s recommended processing conditions).
• High throughput
  In the typical wafer thinning process, wafer grinding damage is removed (stress relief) with dry polishing after rough and fine grinding are performed. DMG8762 can reduce polishing time by optimizing the processing point and controlling the polishing amount, and can improve wafer cleaning and drying functions, achieving approximately 1.5 times higher UPH^*4 than DGP8761.

  *4 UPH: Units Per Hour, indicating the number of mirror wafers processed per hour under DISCO’s recommended conditions.

• Metrology function installation possible
  The entire surface of a thinned wafer can be measured, and data such as “thickness variation,” “edge cracking or breakage shape,” and “particle quantity” can be recorded.

Dry Etcher DME8061

• Responding to the need for higher die strength
  The need for higher die strength has increased as devices have become thinner. Dry etching after thinning can remove damage generated during grinding/polishing without making contact with the wafer. This is especially advantageous during the DBG process, which performs stress relief after die separation, because damage to the side and backside of the die can be removed simultaneously, achieving higher die strength. Thus, yield during die pickup can be expected to improve.

  

Wafer Mounter DMM9200

In grinding, wafers are thinned after backgrinding tape (BG tape) is mounted to protect the pattern side. Then, due to the difficulty of handling thinned wafers, the BG tape is peeled after the thinned wafer is mounted onto dicing tape with a dicing frame, and the dicing frame is then transferred. The wafer mounter DMM9200 performs the tape peeling and mounting procedure automatically.

• Achieves extended, continuous operation
  DMM9200 can perform equipment maintenance even during operation by changing the supply method for the dicing tape and of the tape frame required for tape change, and by optimizing the BG tape disposal method after peeling, reducing equipment downtime.

Upcoming Schedule

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※ Equipment notations in this press release were revised due to changes in equipment names (Dec. 7th, 2020).