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Method for real-time in-place interface formation detection during wafer bonding

IP.com Disclosure Number: IPCOM000019039D
Publication Date: 2003-Aug-27
Document File: 4 page(s) / 72K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for real-time in-place interface formation detection during wafer bonding. Benefits include improved functionality, in-line monitoring, improved yield, an improved production environment, and improved design flexibility.

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Method for real-time in-place interface formation detection during wafer bonding

Disclosed is a method for real-time in-place interface formation detection during wafer bonding. Benefits include improved functionality, in-line monitoring, improved yield, an improved production environment, and improved design flexibility.

Background

         Wafer bonding is one of the promising candidates for three dimensional (3-D) integrated circuit fabrication. This conventional technique relies on copper-copper bonding to create ultradense interconnects.

         Conventionally, no in-place or real-time analysis techniques exist to monitor bonding in conventional aligner/bonder systems. Typically, in wafer bonding, two wafers are pressed together at high pressure and moderate temperature (see Figure 1).

General description

         The disclosed method detects the onset and completion of interface formation during wafer bonding using ultrasonic sound waves.

         The disclosed method enables the detection of interface formation and completion of bonding of two wafers for 3-D wafer stacking using ultrasound waves. Acoustic waves transmitted to and reflected from the samples can be used to effectively detect interface formation.

         The disclosed method provides an in-place means to detect the onset and the endpoint of the bonding process in real time, saving enormous time in post-processing to estimate bond formation. Additionally, potential applications can be extended well beyond metal-metal bonding for 3-D wafer stacking.

Advantages

         The disclosed method provides advantages, including:

•         Improved functionality due to providing real-time monitoring of bond formation as well as being non-destructive

•         Improved yield due to preventing the shorting of interconnects due to over-bonding and opens due to unbonded regions because of insufficient bonding

•         Improved production environment due to providing a rapid real-time feedback from a buried interface nondestructively without requiring a separate tool set

•         Improved design flexibility due to enabling a variety of locations for multiple transducers because only a solid medium is required to propagate the sound waves

•         Improved cost effectiveness due to reducing the costs associated with the time required to monitoring bonding by acoustic microscopy methods because the disclosed method provides similar information realtime

Detailed description

         The disclosed method enables the detection of interface formation and completion of bonding of two wafers for 3-D wafer stacking. Depending on the application, silicon is bonded to silicon or other materials. Alternatively, patterned metal films can be bonded by a creep mechanism. In any case, acoustic waves transmitted to and from the samples can be used to effectively detect interface formation.

         The disclosed method can be implemented using the following steps:

1.         Align two wafers and contact them at room temperature prior to heating or align them and heat them to bond temperature separately.

2. ...