JPH0342510B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a semiconductor device equipped with a cooling structure, and in particular to a semiconductor device equipped with a cooling structure. The present invention relates to a semiconductor device equipped with a cooling structure suitable for removal.

[Background of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of conventional cooling structures for semiconductor devices including semiconductor elements or integrated circuit chips will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a semiconductor device equipped with a conventional cooling structure, and FIGS. 2 and 3 are cross-sectional views of semiconductor devices equipped with other conventional cooling structures.
Components with the same reference numerals as in FIG. 1 indicate equivalent parts.

In FIG. 1, a large number of large-scale integrated circuit (hereinafter referred to as LSI) chips 2 are mounted on a substrate 1 having multilayer wiring by face-to-face bonding.
Housing 3A covers a large number of LSI chips 2.
is attached to the board 1. A large number of flexible bags 4 are attached to the surface of the housing 3A so as to be in contact with the back surface of each LSI chip 2, and a highly fluid and highly thermally conductive liquid 5 is sealed inside the bags 4. bag 4
When installing housing 3A on board 1, each LSI
It is pressed tightly against the chip 2 with a certain pressure. The LSI chip 2 is face-down bonded to the substrate 1 and solder balls 7, and is electrically connected to pins 8 on the back surface of the substrate 1. Since the solder ball 7 is very small, the heat generated by the LSI chip 2 is
Almost no signal can be transmitted to the board through the solder balls 7. Therefore, most of the heat is transferred from the back side of the LSI chip 2 to the housing 3A via the bag 4 filled with a highly thermally conductive liquid 5, and is transferred to the housing 3A by the cooling water flowing through the cooling water channel 9 provided in the housing 3A. removed.

Since the substrate 1 has a multilayer wiring structure, it is generally easily deformed and warped during manufacturing. Furthermore, the bonding method using the solder balls 7 is characterized in that a large number of electrical wirings of the LSI chips 2 are connected at the same time, and it is difficult to make the mounting heights of each LSI chip 2 the same. Therefore, a flexible heat conduction path for thermally coupling the housing 3A and the LSI chip 2 is required. In this regard, in the cooling structure shown in FIG. 1, since the highly thermally conductive liquid 5 sealed in the bag 4 is an incompressible fluid, the bag 4 must be made of a highly flexible material. In addition, the membrane must be highly heat resistant, having corrosion resistance against the sealing liquid 5, and having as high a thermal conductivity as possible, making selection of the bag material extremely difficult. Furthermore, in the bag structure shown in FIG. 1, as the amount of deformation of the LSI chip 2 increases, the internal pressure of the liquid 5 in the bag 4 increases. Therefore, the load applied to the LSI chip 2 also increases, and the solder balls, which have very small dimensions, are plastically deformed. If the cycle of energizing and stopping the LSI chip 2 continues for a long time under this condition, the solder ball 7 will be damaged due to the creep phenomenon.
will break, breaking the electrical connection. on the other hand,
A large tension is also applied to the thin film of the bag 4, reducing the life of the film.

In order to improve the above-mentioned drawbacks, the cooling structure shown in FIG. 2 has been proposed.

The cooling structure shown in FIG. 2 is connected face-down to the substrate 1 by solder balls 7 in the same way as in FIG. 1.
Thin film 10 is applied to the entire top surface of LSI chip 2 and substrate 1.
is coated, and a space region 11 between the inner surface of the housing 3B above the coating thin film 10 is filled with a fluid 12 having high fluidity and high thermal conductivity. The heat generated by the LSI chip 2 is removed by the cooling water flowing from the upper liquid 12 through the housing 3B and through the cooling water passage 9 provided in the housing 3B.

However, a new problem arises in the cooling structure shown in FIG. 2. Many LSIs mounted on board 1
If one of the chips becomes defective, replacement of the defective chip is required. Since multi-chip modules are more expensive than single-chip modules, the entire module cannot be disposed of. However, since a thin film is applied to the back of the LSI chip, it is extremely difficult to repair the thin film. Even if a partial repair is performed, the membrane 10 will have seams. Also, if the entire thin film is peeled off, it will affect the solder balls on good chips.
Decreases module reliability.

Therefore, in order to further solve the above drawbacks, a third
The cooling structure shown in the figure is proposed. Portions equivalent to those in FIG. 1 and FIG. 2 are given the same numbers and their explanations will be omitted.

A bag 14 filled with a highly fluid and highly thermally conductive fluid 13 is inserted between a large number of LSI chips 2 and the inner surface of the housing 3C. Each LSI chip 2 is cooled by contacting this bag 14. However, the following problem occurs in the cooling structure shown in FIG. That is, in order to improve the cooling performance of the LSI chip 2, the adhesion with the bag 14 must be improved. Therefore, the membrane of the bag 14 is required to be thin and flexible as in the case of FIG. Also, unlike in FIG. 1, the bag 14 comes in contact with the edge of the LSI chip 2, so there is a risk that the bag 14 will break.
There are problems with reliability for long-term use.

[Purpose of the invention]

The present invention has been made in order to solve the problems of the prior art described above, and is capable of absorbing various displacements such as board warpage, connection displacement of semiconductor chips, deformation during assembly of the cooling structure, and thermal deformation. It is an object of the present invention to provide a semiconductor device equipped with a cooling structure that is functional and has excellent cooling performance.

[Summary of the invention]

A semiconductor device according to the present invention includes a substrate, a plurality of semiconductor chips mounted on the substrate, and a housing attached to the substrate so as to cover the semiconductor chips. A flexible partition film is provided to partition a spatial region formed by the housing and to cover the upper part of the semiconductor chip, and a flexible partition film is provided to partition a spatial region formed by the housing and to cover the upper part of the semiconductor chip. Further, a plurality of pillows filled with a fluid and highly thermally conductive fluid are provided between the partition film and the back surface of the semiconductor chip, respectively. They are arranged so that they come into contact with each other independently.

Additionally, the present invention is characterized in that a double flexible cooling structure is provided between the top surface of a large number of semiconductor chips and the inner surface of the housing in order to absorb various displacements of the semiconductor device. . That is,
A mechanism for absorbing large displacements common to each semiconductor chip, such as warpage of the substrate and deformation of the entire cooling structure, and a mechanism for absorbing connection variations of each semiconductor chip are separated.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a cross-sectional view of a semiconductor device equipped with a cooling structure according to one embodiment of the present invention, and FIGS. 5, 6, and 7 all show cooling structures according to other embodiments of the present invention. 1 is a sectional view of a semiconductor device equipped with the same technology. In each of these figures, the same reference numerals as in FIG. 1 indicate parts equivalent to those in the prior art.

First, one embodiment of the present invention will be described with reference to FIG.

A large number of LSI chips 2 are electrically connected and the chips are fixed by face-to-face bonding via a multilayer wiring board 1 and minute solder balls 7.
A housing 3 is attached to the board 1 so as to cover a large number of LSI chips 2. A highly flexible and deformable partition film 15 is provided between the upper surface of the large number of LSI chips 2 and the inner surface of the housing 3, and a fluidic region is provided in the space formed by the partition film 15 and the inner surface of the housing 3. It is filled with a rich and highly thermally conductive fluid 16. On the other hand, on the opposite surface of the partition film 15, a plurality of independent pillows 17 are provided, each corresponding to a plurality of LSI chips 2. These pillows 17 are covered with a fluid and highly thermally conductive fluid 16' by a thin coating film 18 so as to be able to come into good contact with the back surface of each LSI chip 2 independently.

Note that the partition film 15 may be made of thin metal foil, synthetic resin, or the like.

In addition, the fluid 16, 16' is a fluid with high thermal conductivity.
is preferably a liquid metal or thermally conductive grease.

Additionally, the thin coating 18 may cause the internal fluid 16' to
It is preferable to use a heat-resistant material that has corrosion resistance and a thermal conductivity as high as possible, such as Parylene film (trade name). The rest of the structure is the same as the conventional example, so the explanation will be omitted.

Next, the operation of this embodiment configured as described above will be explained.

A plurality of pillows 17 are provided in advance on the partition membrane 15. After the housing 3 having the above structure is placed over the substrate 1, the fluid 16 is supplied to the partition membrane from the fluid sealing hole 19 in the housing 3. 15 and the inner surface of the housing 3, warping of the substrate 1, deformation of the entire cooling structure, and dimensional errors during assembly are caused by the deformation of the partition film 15 and the fluid 16.
The common displacement of each LSI chip 2 can be absorbed. Furthermore, by slightly increasing the sealing pressure of the fluid 16, the pillow 17 in contact with each LSI chip 2 is also deformed little by little, and variations in connection of each LSI chip 2 can be absorbed. When the cooling structure is assembled in such a state, the heat generated from the LSI chip 2 passes through the plurality of pillows 17, and then passes through the partition membrane 15,
The fluid is transmitted to the fluid 16, the housing 3, and the cooling water channel 9 one after another and is cooled. Since the plurality of pillows 17 can contact each of the plurality of LSI chips 2 independently, the cooling performance can be significantly improved.

Furthermore, if the spatial region formed by the partition film 15 and the substrate 1 is filled with a highly thermally conductive gas such as helium, the contact thermal resistance between the pillow 17 and the LSI chip 2 can be kept low.

Next, another embodiment of the present invention will be described with reference to FIG. The example in FIG. 5 is a modification of the example in FIG. 4, and the same reference numerals as in FIG. 4 indicate equivalent parts.

In this example, the partition membrane 20 includes a bellows structure portion 20a on the outer periphery so as to surround the pillow 17. In the example shown in FIG. 4, even if the partition belly is made of metal foil, the flexibility of the foil is not necessarily large, so in the example shown in FIG. It is an enhanced version of

Next, still another embodiment of the present invention will be described with reference to FIG. The example in FIG. 6 is a modification of the pillow 7 in the example in FIG. 4 or 5,
The same reference numerals as in FIG. 4 indicate the same parts.

In this example, in order to make it easier to fill the plurality of pillows 17 with the fluid 16', the partition membrane 15 is placed in contact with the in-pillow sealing fluid 16', and a cradle 21 associated with the intervening member is
has been established.

Next, still another embodiment of the present invention will be described with reference to FIG. The example in FIG. 7 is an application example in which the same effect as the example in FIG. 6 is expected, and the same reference numerals as in FIG. 4 indicate the same parts.

In this example, in order to make it easier to fill the plurality of pillows 17 with the fluid 16', a convex portion related to the intervening member is placed at the contact area between the partition membrane 15' and the intra-pillow sealing fluid 16'.
5'a is provided, and the convex portion 15'a is formed by forming slight irregularities on the partition film 15'.

According to each embodiment of the present invention, each LSI
We consider the displacement of the chip to be a large displacement of the entire board, and
Small variations between LSI chips can be separated and absorbed. Therefore, the thermal resistance between each LSI chip and the housing can be kept low. Therefore, the thermal reliability of the LSI chip is improved, and as a result, the reliability of the entire electronic device using the semiconductor device can be improved.

In each of the above embodiments, an example of a semiconductor device equipped with an LSI chip used in an ultra-large computer, etc. was explained, but the present invention is not limited to only an LSI chip, but can also be applied to a semiconductor device equipped with a semiconductor chip that can be expected to have the same effect. This is a general-purpose cooling structure for semiconductor devices.

〔Effect of the invention〕

As explained above, according to the present invention, the present invention has a function of absorbing various displacements such as warpage of the substrate of a semiconductor device, connection displacement of semiconductor chips, deformation during assembly of the cooling structure, and thermal deformation, and A semiconductor device having a cooling structure with excellent performance can be provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor device equipped with a conventional cooling structure, FIG. 2 is a cross-sectional view of a semiconductor device equipped with another conventional cooling structure, and FIG. 3 is still another conventional example. FIG. 4 is a cross-sectional view of a semiconductor device equipped with a cooling structure according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view of a semiconductor device equipped with a cooling structure according to another embodiment of the present invention. 6 and 7 are all partial sectional views of a semiconductor device equipped with a cooling structure according to still another embodiment of the present invention. 1...Substrate, 2...LSI chip, 3...Housing, 15, 15'...Partition membrane, 15'a...Protrusion, 16, 16'...High thermal conductivity fluid, 17...
Pillow, 20... Partition membrane, 20a... Bellows structure part.

Claims (1)

[Claims] 1. A semiconductor device comprising a substrate, a plurality of semiconductor chips mounted on the substrate, and a housing attached to the substrate so as to cover the semiconductor chips, wherein the substrate and the housing A flexible partition film is provided to partition the formed spatial region and to cover the upper part of the semiconductor chip, and a flexible partition film is provided in the spatial region formed by the partition film and the housing. A plurality of pillows filled with a fluid highly thermally conductive fluid are filled between the partition membrane and the back surface of the semiconductor chip, and each pillow is independently contacted with the plurality of semiconductor chips. What is claimed is: 1. A semiconductor device equipped with a cooling structure, characterized in that the cooling structure is arranged so as to 2. In what is stated in claim 1,
A semiconductor device equipped with a cooling structure in which a bellows structure is provided on a partition membrane. 3. A semiconductor device according to claim 1 or 2, which includes a cooling structure that uses a low melting point liquid metal as a fluid and highly thermally conductive fluid. 4. A semiconductor provided with a cooling structure in which a spatial region formed by a partition film and a substrate is filled with a highly thermally conductive gas in any one of claims 1 to 3. Device. 5. In any one of claims 1 to 4, a cooling structure is provided in which an intervening member for assisting the filling of fluid is provided at the contact portion between the partition membrane and the sealing fluid in the pillow. Semiconductor device equipped with