1. Field of the Invention
The present invention relates to a semiconductor device that includes a low dielectric constant film.
2. Description of the Background Art
With progresses in the miniaturization of semiconductor devices, the parasitic capacitance of copper wires has become approximately the same as the input/output capacitance of transistors, preventing increase in the speed of the device operation. Therefore, ways to introduce an insulating film, of which the relative dielectric constant is lower than that of a conventional silicon oxide (SiO2, specific dielectric constant k≈4), have been actively sought. When relative dielectric constant k becomes small, however, the physical strength of an insulating film becomes inferior. In particular, when relative dielectric constant k becomes smaller than 3.5, sufficient physical strength cannot be maintained, leading to a problem. In the following, a film of which relative dielectric constant k is smaller than 3.5 is referred to as “low dielectric constant film,” in the present invention.
During heat cycle testing, after semiconductor devices have been packaged, temperature is changed, for example, from −65° C. to 150° C., and therefore, low dielectric constant films receive stress from resin portions, and as a result, in some cases, the low dielectric constant films peel. The lower the physical strength of a low dielectric constant film, the more significant peeling becomes. In addition, as for the location of peeling, it is particularly significant in the vicinity of chip corners, where stress concentrates.
In general, when moisture enters into the inside of a chip of a semiconductor device, the operation properties of the device deteriorate, and for this reason, a pattern that is referred to as a seal ring (also referred to as “guard ring”) is formed, in order to prevent entering of moisture from sides on the outer periphery of the chip. The seal ring is arranged in closed loop form in a plan view, where metal portions, such as contacts and wires that are used within the chip, are aligned in the upward and downward direction, and these layers are connected to each other through a structure in trench form that is also made of metal, so that a metal wall is formed. In a plan view, the seal ring becomes rectangular, with an outer periphery that is constantly spaced from the outer periphery of the chip.
When a low dielectric constant film is destroyed due to stress that is received from resin, as described above, cracking eventually progresses and reaches the seal ring. When cracking reaches the seal ring, the seal ring is easily destroyed. Once the seal ring is destroyed, moisture enters into the inside of the chip, causing a failure in the operation of the device. Furthermore, in extreme cases, cracking may progress as much as 500 μm and, in some cases, directly cut wires inside the chip.
In order to prevent destruction of the seal ring by cracking, several technologies have been proposed. U.S. Pat. No. 6,365,958, for example, discloses an arrangement of a member having a structure where a number of layers of lattice wires are arranged so as to overlap in the upward and downward direction, and lattice wires which are on top of one another are connected by means of vias that are made of metal outside of the seal ring as a sacrifice pattern for stopping the progress of cracking. U.S. Pat. No. 5,572,067 discloses an arrangement of a sacrifice corner structure where a lower layer wire that is parallel to the direction toward the center from the corner of the chip and an upper layer wire that is oriented perpendicular to this cross each other and are connected to each other by means of a via in a chip corner portion. U.S. Patent Publication No. 2004/0002198 discloses the placement of dummy metal patterns where a non-quadrilateral seal ring is used and placed in a corner portion of the chip, where a lower layer wire and an upper layer wire are connected in lattice form on both sides of the seal ring.
Japanese Patent Laying-Open No. 2004-172169 discloses a reinforcing pattern where a lower layer wire and an upper layer wire are connected through a via and an arrangement of a reinforcing pattern in wall form made of copper in the vicinity of a chip corner.
Even in the case where a structure that becomes a sacrifice pattern is arranged in the vicinity of a chip corner in accordance with a proposed technology, such as those that have been as described above, destruction of the seal ring by cracking cannot be sufficiently prevented. In addition, when the sacrifice pattern is made too great, a problem arises where the area on which circuits or the like are arranged becomes too small.
An object of the present invention is to provide a semiconductor device which can prevent destruction of a seal ring by cracking more efficiently and without fail.
In order to achieve the aforementioned object, a semiconductor device according to the present invention is a semiconductor device which includes a low dielectric constant film of which the relative dielectric constant is less than 3.5, and which includes a seal ring protrusion provided with one or more seal rings that is a moisture blocking wall in closed loop form in a plan view, and in which at least one of the seal rings is in inward protruding form in the vicinity of a chip corner.
The above described and other objects, characteristics, aspects and advantages of this invention will be clarified in the following detailed description of this invention, and are best understood in conjunction with the accompanying drawings.
First, prior to making the present invention, the inventors examined in detail how cracking occurs. An actual state where cracking has occurred that was found as a result is described with reference to
During heat cycle testing, a shear force is applied in the direction of arrow 2 due to contraction of the resin (not shown) that covers the upper side. Low dielectric constant films have low physical strength, and therefore, a crack 1 occurs, originating from a chip corner. The inventors have examined cracking in low dielectric constant films in detail, and as a result, have found the following.
Firstly, the inventors have found that cracks, such as crack 1, easily occur, particularly in interfaces on the lower side of low dielectric constant films. Furthermore, the inventors ascertained that the probability of cracks such as crack 1 occurring in the low dielectric constant film that is the lowest from among a number of low dielectric constant films is the highest.
Secondly, the actual state of a crack while progressing is clarified in a plan view.
Thirdly, it has also been found that cracks occur in the interface on the lower side of low dielectric constant film 105a, as shown in
The present invention was achieved on the basis of these findings.
With reference to
This semiconductor device is provided with a sacrifice pattern 124 which is a structure in wall form for preventing the progress of cracks outside of seal ring protrusion portion 10 from the center of the chip.
Here, as shown in
Though one or more sacrifice patterns such as sacrifice pattern 124 can provide to a certain degree the effects of the present invention, it is preferable to provide a number of sacrifice patterns, and therefore, a sacrifice pattern group 3 is formed of a number of sacrifice patterns such as sacrifice pattern 124 in the example of
According to the present embodiment, at least one seal ring 123 has a form that includes a seal ring protrusion portion 10 in inward protruding form in the vicinity of a chip corner 4, and therefore, cracks that originate from chip corner 4 and progress hit the seal ring in a form that is close to the form that is drawn by the ends of actual cracks, and as a result, it becomes possible to prevent the progress of cracks efficiently. Furthermore, in the present embodiment, seal ring protruding portion 10 has seal ring diagonal side 9, and therefore, seal ring 123 stands parallel to the diagonal side portion in the center of the ends of progressing cracks. Accordingly, it becomes difficult for seal ring 123 to be destroyed by cracks. Furthermore, according to the present embodiment, seal ring protruding portion 10 has a first side 7 and a second side 8, and therefore, seal ring 123 has a number of portions which are arranged parallel to progressing cracks, such as bended lines 24a and 24b shown in
According to the present embodiment, sacrifice pattern 124 is arranged so that cracks that progress so as to spread from chip corner 4 are prevented from progressing before they reach seal ring 123 when they reach sacrifice pattern 124. Sacrifice pattern 124 is, as a whole, a structure made of a metal in wall form using interlayer connection portions in trench form, and therefore, even in the case where cracks that have progressed along an interface on the lower side of one low dielectric constant film hit a wire layer of a certain height of sacrifice pattern 124 and avoid the wire layer so as to pass over the wire layer and progress through the low dielectric constant film above this low dielectric constant film, further progress can be prevented.
According to the present embodiment, as shown in
In particular, in a preferable configuration, as shown in
Here, though in the example shown in
A configuration where only one sacrifice pattern 13 in straight line form is arranged, a configuration where only one sacrifice pattern 124 in bent line form and a configuration where only one sacrifice pattern 13 in straight line form and only one sacrifice pattern 124 in bent line form, that is to say, only two lines in total, are arranged within a region that is surrounded by seal ring protrusion portion 10 also fall within the scope intended by the technical idea of the present invention, although the effects of suppressing the progress of cracks are smaller, in comparison with the aforementioned examples.
Here, though it is preferable for the number of sacrifice patterns 124 that are included in sacrifice pattern group 3 to be arranged in such a manner that the sacrifice patterns 124 that are closer to the center the chip have a longer sacrifice pattern diagonal side 11, effects can be gained to a certain degree, even in the case where only some of the number of sacrifice patterns 124 that are included in sacrifice pattern group 3 are aligned in such an order, in addition to the case where all sacrifice patterns 124 that are included in sacrifice pattern group 3 are aligned in such an order. Accordingly, it can be said that it is preferable for at least some of the number of sacrifice patterns to be arranged in such a manner that the sacrifice patterns that are closer to the center of the chip have a longer sacrifice pattern diagonal side.
With reference to
According to the present embodiment, the group includes sacrifice patterns 23 in closed loop form, and therefore, moisture can be prevented from entering into the region surrounded by sacrifice patterns 23. Low dielectric constant films allow moisture to enter very easily, in comparison with silicon oxide films and the like. In the case where moisture enters into a low dielectric constant film, the physical strength further deteriorates, and moisture does not enter into the inside of sacrifice patterns 23 in closed loop form, as long as sacrifice patterns 23 are not destroyed, and therefore, deterioration in the physical strength of the low dielectric constant films can be prevented, and thus, the progress of cracks can be prevented. Particularly, in the case where a number of sacrifice patterns 23 in closed loop form are arranged in concentric form, the outermost sacrifice pattern 23 preferably provides broadly ranging collective regions into which no moisture enters. In the case where some sacrifice patterns in closed loop form on the outside are destroyed, some regions can be prevented from letting moisture in, if one or more sacrifice patterns in closed loop form remain on the inside.
Here, though the semiconductor device is provided with sacrifice pattern group 12 according to the present embodiment, an arrangement of only one sacrifice pattern in closed loop form, instead of sacrifice pattern group 12, has effects to a certain degree, even though the effects are inferior to the aforementioned example.
With reference to
According to the present embodiment, more than one seal ring is provided, so that the probability of destruction of the seal ring that is the closest to the center of the chip, and thus, hindering of the operation of the device can be made low when cracking progresses.
Though according to the present embodiment, the seal ring is double, it may be triple or more, instead of double. Here, it is necessary to note that the area that can be utilized inside of the seal rings decreases when the number of seal rings is increased. Though according to the present embodiment, a configuration where more than one seal ring is introduced into the example of
With reference to
According to the present embodiment, sacrifice pattern 15 in L shape is provided, and therefore, initial cracks that have occurred, if any, from chip end surfaces 5 and 6 at the time of dicing of the wafer can be prevented from spreading to a certain degree, by sacrifice pattern 15 in L shape. In the case where cracks originating from these initial cracks progress toward the center of the chip during heat cycle testing, the number of sacrifice patterns 13 which are included inner sacrifice pattern group 16 prevent the progress of cracks. In this manner, the combination of sacrifice pattern 15 in L shape and inner sacrifice pattern group 16 makes prevention of the progress cracks effective. Here, though the example of
With reference to
According to the present embodiment, outer seal ring 25 is provided, so that initial cracks that have occurred, if any, from chip end surfaces 5 and 6 at the time of dicing of the wafer can be prevented from spreading to a certain degree, by outer seal ring 25. Therefore, the same effects as those of the fourth embodiment can be gained. Furthermore, outer seal ring 25 has the function of preventing the inner region thereof from allowing moisture to enter, and therefore, the physical strength of the inner region of outer seal ring 25 can be prevented from deteriorating as a result of moisture that has entered.
Here, though outer seal ring 25 surrounds sacrifice pattern group 14 and seal ring 123 in the example of
Here, though one outer seal ring 25 is provided in the example of
With reference to
According to the present embodiment, sacrifice patterns 26 are connected to each other by means of linked layer 18, and therefore, the strength of the entirety of sacrifice pattern group can be increased, and thus, the effect of opposing the progress of cracks can further be increased.
It is preferable for linked layer 18 to be in mesh form in a plan view, as in the example shown in
Here, it is preferable for any of the aforementioned embodiments to have an arrangement where a sacrifice pattern blocks the lowest layer from among the low dielectric constant films. In the case where there is only one layer of a low dielectric constant film, “the lowest layer from among the low dielectric constant films” means this layer. Cracking easily occurs in the lowest layer from among the low dielectric constant films, and therefore, in the case where a sacrifice pattern is arranged so as to block the lowest layer from among the low dielectric constant films, the same phenomenon as that where cracks reach seal ring 123 after they have progressed along the interface on the lower side of a low dielectric constant film in
Significant effects can be gained also in a semiconductor device that includes a number of low dielectric constant films according to the present invention. It is preferable for sacrifice patterns to be arranged so as to block all of the number of low dielectric constant films in the semiconductor device that includes the number of low dielectric constant films. As described with reference to
Furthermore, it is preferable for all of the aforementioned embodiments to have an arrangement where a sacrifice pattern is separated from a seal ring in a plan view. In all of the aforementioned illustrations, the sacrifice patterns are arranged so as to be separated from the seal rings in a plan view, and this can lower the probability of a state occurring where the seal rings are peeled by being pulled by the displacement of a peeling portion, in the case where a sacrifice pattern is destroyed and peels.
Here, where, in each of the aforementioned embodiments, the expression “forms approximately the same angle with two chip end surfaces 5 and 6 that form a chip corner 4” is used when referring to the state of sealing diagonal side 9, sacrifice pattern diagonal side 11 and the like, this means a case where angles of 40° to 50° are formed for chip corner 4 that forms, for example, a right angle, in addition to a case where an angle of 45° is formed with the two respective chip end surfaces 5 and 6. That is to say, a state where a diagonal side is inclined at 40° relative to chip end surface 5 and inclined at 50° relative to chip end surface 6, for example, is also included in the expression. Here, a case where an angle of approximately 45° is formed for both of chip end surfaces 5 and 6 is most preferable. This is because such an arrangement can make the diagonal side oppose progressing cracks precisely head-on.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
2004-264014 | Sep 2004 | JP | national |
This application is a Continuation of U.S. application Ser. No. 11/220,603, filed on Sep. 8, 2005, and claims the benefit of priority of Japanese Application No. 2004-264014, filed on Sep. 10, 2004, the contents of each of which is incorporated herein by reference.
Number | Name | Date | Kind |
---|---|---|---|
5572067 | Thalapaneni | Nov 1996 | A |
6028347 | Sauber et al. | Feb 2000 | A |
6365958 | Ibnabdeljalil et al. | Apr 2002 | B1 |
20030213980 | Tanaka et al. | Nov 2003 | A1 |
20030218254 | Kurimoto et al. | Nov 2003 | A1 |
20040002198 | Lee et al. | Jan 2004 | A1 |
20040150073 | Matumoto et al. | Aug 2004 | A1 |
20050087878 | Uesugi et al. | Apr 2005 | A1 |
20050127395 | Saigoh et al. | Jun 2005 | A1 |
20050269702 | Otsuka | Dec 2005 | A1 |
20060163720 | Hirata | Jul 2006 | A1 |
Number | Date | Country |
---|---|---|
2003-86590 | Mar 2003 | JP |
2003-338504 | Nov 2003 | JP |
2004-172169 | Jun 2004 | JP |
2004-253773 | Sep 2004 | JP |
2006-41244 | Feb 2006 | JP |
Number | Date | Country | |
---|---|---|---|
20090189245 A1 | Jul 2009 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 11220603 | Sep 2005 | US |
Child | 12410170 | US |