Provided are semiconductor die flip chip packages with warpage control and
fabrication methods for such packages. A package includes a heat spreader
that is attached to a die and a stiffener, which are in turn attached to
a package substrate. In general, the stiffener is made of a material that
has a relatively low CTE value. For example, the stiffener material may
have a CTE value less than 12 ppm/.degree. C. The material may also have
a relatively low mass density value of less than 8.9 g/cm.sup.3. Such a
material may include natural graphite or some composite form of it. The
result is a package with less bowing and so improved co-planarity (e.g.,
in compliance with industry specifications) with the surface to which it
is ultimately bound; thereby, improving the reliability of the package.
Moreover, a package that is relatively lighter and more robust than
conventional semiconductor die flip chip packages can be realized.