Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Flip chip
Reexamination Certificate
2002-04-05
2004-10-05
Nguyen, Cuong (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Flip chip
C257S780000, C257S684000, C257S686000
Reexamination Certificate
active
06800945
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a multi-chip-module (MCM) type semiconductor device.
JP-A-11-220077 discloses that a thermal expansion coefficient of a substrate is adjusted to restrain a crack of a semiconductor element or a under-fill layer. JP-A-2000-40775 discloses that a shape of an oblique surface of the under-fill layer is adjusted to restrain the crack of the semiconductor element. JP-A-6-244238 discloses that the semiconductor elements are mounted one by one onto a substrate sequentially in order of semiconductor element thickness from a minimum semiconductor element thickness.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a multi-chip-module (MCM) type semiconductor device of high-reliability against a bending deformation of the MCM type semiconductor device caused by an environment temperature variation during actual operation thereof, a mounting treatment of semiconductor element onto a substrate, a heat generation thereof during actual operation thereof or the like, with a difference in linear expansion coefficient between the semiconductor element and a substrate, a difference in temperature therebetween, an external force applied to the semiconductor device.
According to the invention, a multi-chip-module type semiconductor device comprises, first and second semiconductor elements, a main component of each of the semiconductor elements being semiconductor material to form a semiconductor electric circuit in each of the semiconductor elements, and a substrate adapted to be mounted onto a mother board and to be electrically connected to the mother board, on which substrate the first and second semiconductor elements are mounted to be electrically connected to the substrate, so that the first and second semiconductor elements are electrically connected to the mother board through the substrate.
If a thickness of the second semiconductor element is less than a thickness of the first semiconductor element when an area of the second semiconductor element is more than an area of the first semiconductor element as seen in a stacking direction in which each of the first and second semiconductor elements and the substrate are stacked and/or a length of a side of the second semiconductor element whose length is maximum in comparison with lengths of the other sides of the second semiconductor element as seen in the stacking direction is more than a length of a side of the first semiconductor element whose length is maximum in comparison with lengths of the other sides of the first semiconductor element as seen in the stacking direction, since a stress on a connecting member (for example, bumps) between the substrate and each of the semiconductor elements increases in accordance with an increase of the area and/or the length of the side whose length is maximum in comparison with lengths of the other sides while the stress on the connecting member (for example, bumps) between the substrate and each of the semiconductor elements decreases in accordance with a decrease of the thickness of each of the semiconductor elements, a crack on the connecting point or separation between the semiconductor element and the substrate at the connecting point is effectively prevented by decreasing the thickness of the second semiconductor element. It is preferable for the thickness of each of all semiconductor elements on the substrate to be not more than 0.4 mm.
The multi-chip-module type semiconductor device may further comprise a synthetic resin (corresponding to an under-fill) adhering to the substrate and each of the first and second semiconductor elements, and/or a wiring layer between the substrate and at least one of the first and second semiconductor elements, the wiring layer including a synthetic resin layer and an electrically conductive member (connecting electrically therethrough the substrate to the at least one of the first and second semiconductor elements) extending in a transverse direction transversing the stacking direction, in such a manner that an electrical connecting point between the semiconductor element and the electrically conductive member is distant away from an electrical connecting point between the electrically conductive member and the substrate in the transverse direction. When each of the first and second semiconductor elements includes a first surface facing to the substrate and a second surface as a reverse surface with respect to the first surface in a stacking direction in which each of the first and second semiconductor elements and the substrate are stacked, and the thickness of the second semiconductor element is smaller than the thickness of the first semiconductor element, it is preferable that the second surface of the first semiconductor element is prevented from being a grinder-finished surface while the second surface of the second semiconductor element is the grinder-finished surface.
If the thickness of the first semiconductor element is smaller than the thickness of the second semiconductor element when the multi-chip-module type semiconductor device further comprises a synthetic resin member (corresponding to the under-fill) adhering to the first semiconductor element and the substrate at the inside of the first semiconductor element as seen in the stacking direction, while a synthetic resin (for example, corresponding to the under-fill) whose Young's modulus is not less than Young's modulus of the synthetic resin member is prevented from adhering to the second semiconductor element and the substrate at the inside of the second semiconductor element as seen in the stacking direction, since a connecting rigidity between the first semiconductor element and the substrate connected to each other through bumps is made more than a connecting rigidity between the second semiconductor element and the substrate connected to each other through bumps, by reinforcing the connecting rigidity between the first semiconductor element and the substrate with the synthetic resin member, the stress on the semiconductor element increases in accordance with an increase of the connecting rigidity between the semiconductor element and the substrate, and the stress on the semiconductor element decreases in accordance with the decrease the thickness thereof on the substrate, the crack or excessive stress on the first semiconductor element whose connecting rigidity is reinforced by the synthetic resin member is effectively prevented.
If the thickness of the first semiconductor element is smaller than the thickness of the second semiconductor element when the multi-chip-module type semiconductor device further comprises a first synthetic resin through which the substrate and the first semiconductor element are connected to each other and a second synthetic resin through which the substrate and the second semiconductor element are connected to each other, and Young's modulus of the first synthetic resin (for example, corresponding to the under-fill) is larger than Young's modulus of the second synthetic resin (for example, corresponding to an elastomer stress or deformation absorbing layer
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), since the connecting rigidity between the first semiconductor element and the substrate connected to each other through bumps is made more than the connecting rigidity between the second semiconductor element and the substrate connected to each other through bumps, by relatively more effectively reinforcing the connecting rigidity between the first semiconductor element and the substrate with a difference in Young's modulus between the first synthetic resin and the second synthetic resin, the stress on the semiconductor element increases in accordance with the increase of the connecting rigidity between the semiconductor element and the substrate, and the stress on the semiconductor element decreases in accordance with the decrease of the thickness thereof on the substrate, the crack or excessive stress on the first semiconductor element whose connecting rigi
Imasu Satoshi
Naito Takahiro
Naka Yasuhiro
Tanaka Naotaka
Yoshida Ikuo
Hitachi , Ltd.
Nguyen Cuong
Townsend and Townsend / and Crew LLP
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