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Method for eliminating wafer bow and warp in diamond-on-silicon substrates

IP.com Disclosure Number: IPCOM000032205D
Publication Date: 2004-Oct-26
Document File: 3 page(s) / 20K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for eliminating wafer bow and warp in diamond-on-silicon substrates. Benefits include improved functionality and improved performance.

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Method for eliminating wafer bow and warp in diamond-on-silicon substrates

Disclosed is a method for eliminating wafer bow and warp in diamond-on-silicon substrates. Benefits include improved functionality and improved performance.

Background

      The large thermal conductivity of diamond material makes it useful as an integrated thermal-spreading layer in integrated circuits (ICs). However, the use of diamond material requires a high deposition temperature. Additionally, a large mismatch occurs between the coefficient of thermal expansion (CTE) of the silicon wafer and the diamond film. As a result, a large bow of the wafer can occur at room temperature, making subsequent processing difficult if not impossible (see Figure 1).

       The single-sided deposition of thick diamond layers on bulk silicon wafers results in significant wafer bow due to CTE mismatch. Complete elimination of wafer warp is extremely important to enable further processing of the wafer, such as the subsequent bonding of the top silicon device layer.

      The flatness of the substrate is very important for die-attachment and uniform heat spreading during assembly and testing.

General description

      The disclosed method is the double-sided deposition of equal thicknesses of diamond material on silicon wafers to eliminate wafer bowing and warpage.

              The key elements of the disclosed method include:

•             Multilayer substrate built on a bulk silicon substrate

•             Silicon device layer

•             Diamond layer separating the device layer and the substrate

•             Diamond layer at the back of the substrate

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to enabling further processing of diamond-containing wafers
•             Improved performance due to eliminating warpage

 


Detailed description

      The disclosed method includes the simultaneous deposition of two identical diamond layers on opposite sides of a silicon wafer (see Figure 2). Because the CTE mismatch stresses are equal...