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Water jet-guided laser system for scribing and singulation applications

IP.com Disclosure Number: IPCOM000101719D
Publication Date: 2005-Mar-16
Document File: 4 page(s) / 23K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a water jet-guided laser system for scribing and singulation. Benefits include improved functionality, improved performance, improved throughput, improved yield, and cost effectiveness for dicing and scribing applications

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water jet-guided laser system for scribing and singulation applications

Disclosed is a method for a water jet-guided laser system for scribing and singulation. Benefits include improved functionality, improved performance, improved throughput, improved yield, and cost effectiveness for dicing and scribing applications

Background

                            The conventional wafer-dicing process has two steps, laser scribing and saw-based singulation (see Figure 1). The quality of singulation depends on the dimensions of the wafer streets separating the functional dies and the throughput time. The industry road map is narrower singulation streets and thinner wafers.

      Singulation can result in a large amount of debris on die bumps from silicon and stacked dice. Contaminated die bumps result in 100% nonwet yield loss. To alleviate the loss, a protective polymer coating may be applied to the Si wafer prior to laser scribing to protect the die bumps from being exposed to the debris. This process adds extra processing steps during assembly. Additionally, the increased laser energy required to overcome the wafer coating results in more heat generation, a wider laser-affected zone, and increased scribe debris at the die edges/corners. which  is a concern for package assembly and reliability. This solution path is not expected to be acceptable with thinner die configurations.

General description

      The disclosed method uses both  a laser beam and a highly pressurized water jet to perform wafer dicing and scribing/singulation. The water jet confines the laser beam along its propagation axis, minimizes scattering and divergence loss, and decreases the amount of debris along the dicing/singulation path. 

      Depending on the application, the working fluid in the guiding jet can be engineered to contain abrasive particles. This assists in debris removal and govern the rate of the material removal process, especially with the brittle materials of a die stack up.

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to enabling a one step, laser based direct process for both scribing and singulation

•             Improved functionality due to minimizing the impact on the active area of the wafer (die) and preventing unnecessary heat from propagating through the wafer

•             Improved performance due to increasing the utilized portion of the laser beam intensity and decreasing energy loss by confining the beam with the fluid.

•             Improved performance due to reducing the width of the laser heat-affected region, improving the kerf edge quality along the wafer street sides

•             Improved performance due to reducing the debris accumulation at the die corner/edges

•             Improved performance due to enhancing debris removal by using the water jet with the laser beam

•             Improved performance due to improving control by increasing the number of contro...