JPH05285936A - Dividing method for semiconductor base - Google Patents

Abstract

PURPOSE:To provide a dividing method for a semiconductor base without generating chippings and cracks, also without affecting adversely to element characteristics and with a cut face in the good state. CONSTITUTION:A semiconductor base 21 is provided with a zincblende crystal structure with its main surface (100). Line ruling is carried out in the direction parallel with OF on the surface of said semiconductor base 21 by a diamond tool to form a scribing channel. Also wet an isotropic etching is applied in the direction perpendicular with OF on the rear face of the semiconductor base 21 to form separating channels. Lastly cleavage separation is carried out by roller pressurizing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate dividing method for dividing a semiconductor substrate into a plurality of small pieces in a manufacturing process of a semiconductor integrated circuit device or the like.

[0002]

2. Description of the Related Art When an integrated circuit is formed on the main surface of a semiconductor substrate and formation of a passivation film for surface protection is completed, usually the back surface processing of the substrate is started. In the back surface processing step of this substrate, depending on the type of integrated circuit and the package mounting form in the subsequent step, the substrate thickness is reduced and the via (VI) is formed.
A) A hole is formed and a back surface metal thin film is formed. Further, in order to improve the adhesion of the backside metal, the backside surface treatment may be performed after the substrate is thinned. Then, the process of dividing the semiconductor substrate into chips is performed, and the semiconductor chips are divided into unit pieces.

III-V group compound semiconductor substrates such as GaAs and InP have been attracting attention and used as materials for high-speed electronic circuits and light emitting / receiving elements in recent years, but they have higher thermal conductivity than conventional Si semiconductor substrates. Is bad. Therefore, GaAs, In
In manufacturing an element using P or the like, the substrate is thinned in order to improve heat dissipation during actual use, and this thinning step is an important process. Further, since materials such as GaAs and InP have a brittle property as compared with Si, a substrate having a certain thickness is required in the process of manufacturing a circuit element. In the case of a substrate having a diameter of 3 inches, a circuit element is usually formed on the substrate having a thickness of about 600 μm, and the substrate is thinned to a desired thickness by lapping or gliding after the element is formed. In the thinning process,
The substrate is usually made to have a thickness of about 100 μm or less, and sometimes it is made as thin as about 50 μm.

The division of the semiconductor substrate into chip pieces is performed at the end of the manufacturing process as described above. As a method of dividing the substrate, conventionally, there are methods such as a diamond point scribing method and a blade scribing method.
The diamond point scribing method is a method of making scratches by scoring with a diamond point tool and applying bending stress to split the substrate by utilizing the cleavage property of the crystal.It is a method of dividing after scribing and breaking. is there. The blade scribing method is a method in which the entire substrate thickness is cut by a blade (rotary grindstone), or a cutting groove is formed in a part of the substrate thickness by the blade and the remaining thickness is divided by braking.

[0005]

However, each of the conventional cutting methods described above has the following problems. That is, GaA
When a substrate made of a brittle material such as s or InP is directly applied to the diamond scribing method or the blade scribing method and is divided into two orthogonal directions, chipping (cracking) or cracking (cracking) occurs in a chip thin piece having a substantially rectangular parallelepiped shape. I got it. Therefore, it has been conventionally difficult to obtain chip flakes without causing such chipping and cracks.

[1] of zinc blende crystals such as GaAs and InP
A semiconductor substrate having a (00) plane as a main surface is shown in FIG. 5 and is most commonly used. Such GaAs, In
In a substrate having a (100) plane composed of P single crystal as a main surface, the cleavage plane is the (110) plane, and the plane perpendicular to the plane parallel to the OF (orientation flat) plane is the cleavage plane. The most common way is to divide. In other words, the substrate is usually divided in the (100) plane in the direction parallel to the OF and in the direction perpendicular thereto. Here, the planes divided and divided are equivalent to the planes parallel to the OF and the planes perpendicular to the OF.
When viewed from one surface side, the property parallel to the OF and the direction perpendicular to the OF are different from each other in view of crystal symmetry. In particular,
The scratch hardness differs between the direction parallel to the OF in the (100) plane and the direction perpendicular thereto, and the degree of chipping during dicing (blade scribing) also differs. Moreover, the cross-sectional shape when patterned and solution-etched is different. That is, in the direction parallel to the OF, etching forms a groove having a normal mesa cross section. In addition, dicing results in less chipping and formation of separation grooves, and scratches of the diamond tool also form good scribe grooves. On the other hand, in the direction perpendicular to the OF, etching forms a groove having a reverse mesa cross section. Moreover, chipping is often caused by dicing, and cracks are likely to occur. Further, it is difficult to form the scribe groove satisfactorily by scratching.

On the other hand, even if it is attempted to form the separation groove by dicing or the like in the OF parallel direction, which is usually easy to cut, it is about 1
Delicate workability (skill) is required for a thinned substrate with a thickness of 00 μm or less that is difficult to handle. Also, large chipping occurs in the OF vertical direction, which is difficult to cut, and the cracks cause fatal damage to the device characteristics. In addition, when a scribe line is formed with a diamond tool, a scribe groove with a width of several μm and a depth of several μm is usually formed. Even in this case, the scribe line is formed in the vertical direction in which the reverse mesa is formed. If it is put in, undesired cracking of the substrate may occur, and it was difficult to form the scribe groove itself.

[0008]

The present invention has been made to solve such a problem, and a semiconductor substrate having a zincblende crystal structure having a (100) plane as a main surface is formed into a plurality of small pieces. In the method of dividing a semiconductor substrate to be divided, from one surface of the semiconductor substrate, a step of forming a separation groove by etching in a direction in which the cross section is in a forward mesa shape by anisotropic etching, and from the other surface of the semiconductor substrate, The step of dividing the semiconductor substrate includes the steps of drawing and bending stress in the direction orthogonal to the above direction and cleaving and separating along the drawing direction.

In addition, a first step of drawing a line from one surface of the semiconductor substrate in a direction in which the cross section becomes a forward mesa shape by anisotropic etching, and thinning the semiconductor substrate from the other surface of the semiconductor substrate to a predetermined size. And a third step of forming a separation groove by etching from the other thinned surface of the semiconductor substrate in a direction orthogonal to the ruled line direction, and bending the semiconductor substrate. A fourth step of applying stress to cleave and separate the semiconductor substrate along the ruled direction is included to divide the semiconductor substrate.

[0010]

The surface etching characteristics of a semiconductor substrate having a zincblende crystal structure whose main surface is the (100) plane are shown in FIGS. 6 and 7. That is, as shown in FIG. 6, when the patterns 16a and 16b are formed by the protective films 15a and 15b on the front and back surfaces 14a and 14b of the semiconductor substrate 14 and the etching is performed, an etching cross section as shown in FIG. It is known that a shape is obtained. As shown in FIG. 7, a groove 17 having a forward mesa etching cross-sectional shape is formed.
c and 17d, and a groove 17 having an inverted mesa etching sectional shape
a and 17b are formed on the front and back surfaces of the semiconductor substrate 14.

That is, on one surface (front surface) of the (100) semiconductor substrate, a forward mesa is formed in a direction parallel to the OF, and the direction parallel to the OF is an easy division direction. In addition, an inverted mesa is formed in a direction perpendicular to OF,
The direction perpendicular to the OF becomes a direction in which division is difficult. On the other hand, on the other surface (back surface) of the semiconductor substrate, the above relationship is reversed, and an inverse mesa is formed in a direction parallel to the OF, and a direction parallel to the OF becomes a direction in which division is difficult. Also,
A forward mesa is formed in the direction perpendicular to the OF, and the direction perpendicular to the OF is a direction in which division is easy. That is, (10
0) The direction of difficult division when viewed from the front side of the semiconductor substrate is
When viewed from the back side, it is equivalent to the direction of easy division when viewed from the front side.

Therefore, in the present invention, the OF is formed from the surface of one substrate on which the forward mesa is formed in the direction parallel to the OF.
After the creases are formed in the direction parallel to, a bending stress is applied to the creases to cause cleavage separation along the crease direction. Also, O
A separation groove is formed by etching in the direction perpendicular to the OF from the other substrate surface where the forward mesa is formed in the direction perpendicular to F.

On the contrary, the separation groove is formed by etching in the direction parallel to the OF from the one substrate surface where the forward mesa is formed in the direction parallel to the OF. In addition, bending stress is applied from the other substrate surface where a forward mesa is formed in a direction perpendicular to the OF to the direction perpendicular to the OF, and a cleavage stress is applied along the ruled direction. To be separated.

When the semiconductor substrate is thinned,
Since the ruled lines for cleavage separation are performed before this thinning step, the semiconductor substrate is divided easily and without causing scratches or cracks. That is, the ruled line is drawn in the state of the substrate thickness that is easy to work and handle. Further, if the etching process is performed after the semiconductor substrate is thinned, the process time is shortened. Here, the step of forming the separation groove by etching can be used together with the via hole forming step.

[0015]

1 to 4 are process sectional views showing a method of dividing a semiconductor substrate according to an embodiment of the present invention. This manufacturing process corresponds to the back surface forming process performed at the final stage of manufacturing the MMIC (monolithic microwave IC).

The semiconductor substrate 21 is made of a GaAs material having a zinc blende crystal structure, and after the integrated circuit forming process on the front side ((100) plane) of the semiconductor substrate 21 is completed, the substrate is moved in a direction parallel to OF with the diamond point tool 20. Ruled lines are formed on the surface, and scribed grooves are formed in the division boundary regions (see FIG. 1). Next, a resist 22 is applied to the front side to protect the surface of the semiconductor substrate 21 (see FIG. 2A). Here, the surface visible in the front of the drawing is the OF surface,
The OF surface is a surface parallel to the paper surface, and the left-right direction of the paper surface is the direction parallel to the OF. The direction from the front to the back of the paper is the direction perpendicular to the OF. The surface of the substrate on which the resist 22 is applied is the (100) plane, which corresponds to the front side of the substrate, and the side opposite to this surface corresponds to the back surface of the substrate. After the resist 22 is hardened, a wax is applied to the surface of the resist 22, and the wax is used as an adhesive, for example, a quartz plate 23.
Is attached to the surface of the resist 22 (see FIG. 7B). At this point, since the substrate thickness is about 600 μm, the wafer is thinned from the back side by grinding, polishing, etc.
It is formed with a thickness of about μm or less (see FIG. 7C). This thinning of the substrate is performed to improve the heat dissipation of the integrated circuit because the semiconductor substrate such as GaAs or InP has poor thermal conductivity.

Next, SiO ₂ is formed on the back surface of the thinned substrate 21.
The film 24 is formed (see FIG. 7D). Then Si
A resist 25 is applied to the surface of the O ₂ film 24 and patterned. Normally, in this patterning, a via hole pattern 25a is formed.
In this embodiment, the isolation region pattern 25b is simultaneously formed in the direction perpendicular to the OF (see FIG. 8E). Therefore, the via hole pattern 25a and the OF vertical separation region pattern 25b can be formed by the same exposure mask, and only one patterning mask is required. Next, the via hole 26 and the separation groove 27 are formed by wet etching using this pattern as a mask (the same (f)).
reference). The separation groove 27 is a direction perpendicular to the OF when viewed from the back side of the semiconductor substrate 21, and is a direction in which a forward mesa is formed by anisotropic etching.

In this via hole formation, wet etching is usually performed until the hole penetrates, so the processing time is determined by the via hole formation conditions. Therefore, by appropriately adjusting the pattern width of the OF vertical separation region pattern 25b, a strip-shaped pellet aggregate in which the OF vertical direction is completely separated can be obtained as in this embodiment, and the separation region can be obtained. It is also possible to cut a groove of any depth. When the groove is simply cut, the OF vertical direction is not completely separated.

Next, after wet-etching, the via holes are pierced and separated in the direction perpendicular to the OF, and then SiO ₂ on the back surface side is formed.
The film 24 and the resist 25 are removed (see FIG. 3 (g)),
Subsequently, the back surface metal 28 is vapor-deposited (see FIG. 6H). At this time, a metal film is also deposited on the via hole 26. Further, if necessary, masking may be performed so that the metal film does not adhere to the OF vertical separation region. The illustrated state shows the case of masking.

Next, the adhesive sheet 29 is attached and fixed to the back surface of the semiconductor substrate 21.
The quartz plate 23 that fixed the front side of the
3 is removed. Further, the resist 22 on the front side is removed (see FIG. 4A). Here, the semiconductor substrate 21
A circuit element is formed on the exposed surface (10
0) plane, and a separation groove is formed in the vertical direction of the OF by etching, so that the substrate is completely separated in the vertical direction of the OF and has a strip shape. Further, a scribe groove formed by a diamond point tool is formed in the OF parallel direction, and the substrate is not completely separated. Finally, a bending stress is applied to the semiconductor substrate 21 by the roller 30 from the fixed side of the semiconductor substrate 21 fixed to the adhesive sheet 29 (see FIG. 2B). Here, the illustrated groove is a scribe groove formed by a diamond tool. By this roller pressing, braking is applied in the OF parallel direction, and the semiconductor substrate 21 is completely cleaved in the OF parallel direction. As a result, the semiconductor substrate 21 is divided into a plurality of substantially rectangular parallelepiped pellets.

As described above, in the semiconductor dividing method according to the present embodiment, the scribe groove is formed by the diamond tool in the direction parallel to the OF from the surface of the semiconductor substrate 21 where the forward mesa is formed in the direction parallel to the OF. Formed and cleaved by roller pressure. Further, a separation groove is formed by wet etching in the direction perpendicular to the OF from the back surface of the semiconductor substrate 21 where the forward mesa is formed in the direction perpendicular to the OF. That is, scribing is not performed in the reverse mesa direction, which is a difficult direction to cut on the substrate surface. Further, since this direction is a forward mesa direction in which cutting is easy when viewed from the back surface of the substrate, wet etching is performed from the back surface in this easy cutting direction. Therefore, the semiconductor substrate 2
On the front surface and the back surface of No. 1, separation grooves are extremely easily formed with good productivity in the direction of easy division, and chipping (cracking) and cracking (breaking) are not generated unlike the conventional case. Moreover, the chip cutting shape is good, and the element performance is not damaged.

Since the scribe groove in the direction parallel to the OF is formed by the diamond tool before the semiconductor substrate 21 is thinned, the wafer is not cracked or chipped when the scribe groove is formed. Moreover, since the groove is formed in the forward mesa direction, the scribe groove does not meander. Further, as a result, since the scribing is performed in only one direction, the grooves do not intersect with each other, and a defect due to this does not occur.

Further, the step of forming the OF vertical separation groove on the back surface of the substrate by etching can be shared with the etching step for forming a via hole which is frequently used in this field, so that the increase in the number of steps can be minimized. Further, since this etching step is performed after the semiconductor substrate 21 is thinned, it can be performed in a relatively short time even if the etching rate is slow,
The process time is shortened. In particular, this effect is effective when the semiconductor substrate is thinned to about 100 μm or less as in this embodiment.

In the description of the above embodiment, OF
Although the etching used for forming the separation groove in the vertical direction is wet etching, it is not necessarily wet etching, and another etching method may be used.
Further, although the semiconductor substrate 21 is described as GaAs in the above embodiment, it has another zinc blende crystal structure such as InP II.
It may be an I-V group compound semiconductor substrate. Further, in the above embodiment, the case where the present invention is applied to the manufacture of the MMIC has been described, but a light emitting element, a light receiving element or the like may be used. In each of these cases, the same effect as that of the above-described embodiment can be obtained.

[0025]

As described above, according to the present invention, O
Separation grooves are formed by diamond scribe or etching in a direction parallel to the OF from one substrate surface where a forward mesa is formed in a direction parallel to F. Also,
Separation grooves are formed by etching or diamond scribing in the direction perpendicular to the OF from the other substrate surface where the forward mesa is formed in the direction perpendicular to the OF. For this reason, the separation groove formation direction on each surface of the substrate is a direction that allows easy division, does not cause chipping or cracks, does not adversely affect element characteristics, and has a good cut surface condition. A method of dividing a semiconductor substrate is provided.

When the semiconductor substrate is thinned,
Since the ruled lines for cleavage separation are performed before this thinning step, the semiconductor substrate is divided easily and without causing scratches or cracks. That is, the ruled line is drawn with a substrate thickness that is easy to work and handle. Further, if the etching process is performed after the semiconductor substrate is thinned, the process time is shortened. Here, the step of forming the separation groove by etching can be used together with the via hole forming step. Therefore, a method of dividing a semiconductor substrate suitable for mass production is provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing a diamond scribe in one embodiment in which the present invention is applied to an MMIC manufacturing process.

FIG. 2 is a first process sectional view showing a semiconductor manufacturing process after diamond scribing in the present embodiment.

FIG. 3 is a second process cross-sectional view of the semiconductor manufacturing process according to the present embodiment, which is performed subsequent to the first manufacturing process shown in FIG. 2.

FIG. 4 is a third process cross-sectional view of the semiconductor manufacturing process according to the present embodiment, which is performed subsequent to the second manufacturing process shown in FIG.

[FIG. 5] (10 of a semiconductor substrate having a zinc blende crystal structure)
It is a perspective view explaining a 0) plane, an OF plane, and other crystal axes.

FIG. 6 is a process sectional view explaining the surface etching characteristics of a (100) semiconductor substrate.

FIG. 7 is a perspective view illustrating surface etching characteristics of a (100) semiconductor substrate.

[Explanation of symbols]

20 ... Diamond point tool, 21 ... Semiconductor substrate having zinc blende crystal structure, 22 ... Surface resist, 23 ...
Quartz plate, 24 ... SiO ₂ film, 25 ... Backside resist, 25
a ... via hole pattern, 25b ... OF vertical separation region pattern, 26 ... via hole, 27 ... OF vertical separation groove, 28 ... back metal, 29 ... adhesive sheet, 30 ... roller.

Claims (3)

[Claims] 1. A method of dividing a semiconductor substrate having a zincblende crystal structure having a (100) plane as a main surface into a plurality of small pieces, wherein one surface of the semiconductor substrate is anisotropic. A step of forming a separation groove by etching in a direction in which the cross section becomes a forward mesa shape; and a step of drawing a line from the other surface of the semiconductor substrate in a direction orthogonal to the direction and applying a bending stress to the drawing direction. And a step of performing cleavage separation along the semiconductor substrate. 2. The method for dividing a semiconductor substrate according to claim 1, wherein in the step of forming the separation groove by etching, the etching is solution etching. 3. A method of dividing a semiconductor substrate, which comprises dividing a semiconductor substrate having a zincblende crystal structure having a (100) plane as a main surface into a plurality of pieces, wherein one surface of the semiconductor substrate is anisotropic. A first step of drawing a line in a direction in which a cross section has a forward mesa shape by etching; a second step of thinning the semiconductor substrate from the other surface of the semiconductor substrate to a predetermined thickness; A third step of forming a separation groove by etching from the other thinned surface in a direction orthogonal to the ruled direction, and applying a bending stress to the semiconductor substrate along the ruled direction. And a fourth step of cleaving and separating the semiconductor substrate.