Patent Application
20200361120
The present invention relates to a segmentation of a semiconductor device substrate, and particularly to a segmentation of substrate in which a device pattern is formed on one main surface and a metal film is formed on the other main surface.
For example, already known as a method of segmenting a semiconductor device substrate such as a silicon carbide (SiC) substrate is a method of performing a scribe process of forming a scribe line on one main surface of a semiconductor device substrate and extending a vertical crack from the scribe line, and subsequently performing a break process of further extending the crack in a thickness direction of the substrate by application of external force, thereby breaking the semiconductor device substrate (for example, refer to Patent Document 1).
The scribe line is formed by pressingly rotating and moving a scribing wheel (cutter wheel) along a predetermined segment position.
The break is performed by making an edge of a breaking blade (a breaking bar) have direct contact with the semiconductor device substrate along the predetermined segment position on the other main surface side of the semiconductor device substrate and further pressing the edge thereof.
The formation of the scribe line and the break are performed in a state where a dicing tape having an adhesion property is attached to the other main surface, and segmented surfaces facing each other are separated by an expansion process of stretching the dicing tape after the break process.
Known as a form of segmenting the semiconductor device substrate is a method of segmenting (singulating) a mother substrate, in which a device pattern formed of a unit pattern of a semiconductor device including a semiconductor layer and an electrode two-dimensionally repeated is formed on one main surface and a metal film is formed on the other main surface, into individual device units.
When such a division is performed by the conventional method disclosed in Patent Document 1, there is a case where the metal film is not completely segmented but remains connected in a position where the metal film should be segmented after the break process, as it were, a thin skin remains in some cases.
Even when such a thin skinned portion remains, the portion in the metal film may be segmented (fractured) in the subsequent expansion process, however, there is a problem that the metal film is easily peeled from a segmented position even if the metal film is segmented.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2012-146879
The present invention therefore has been made to solve the above problems, and it is an object to provide a method capable of preferably segmenting a substrate with a metal film.
In order to solve the above problems, a first aspect of the present invention is a method of segmenting a substrate with a metal film including: a scribe step of scribing a predetermined segment position of a substrate with the metal film in a first main surface of the substrate on which the metal film is not provided using a scribing tool to form a scribe line, thereby extending a vertical crack from the scribe line along the predetermined segment position toward an inner side of the substrate with the metal film, a first break step of making a breaking bar have direct contact with the substrate with the metal film from a side of a second main surface, on which the metal film is provided, of the substrate with the metal film to further extend the vertical crack, thereby segmenting a portion of the substrate with the metal film other than the metal film in the predetermined segment position; and a second break step of making the breaking bar have direct contact with the substrate with the metal film from a side of the first main surface, thereby segmenting the metal film in the predetermined segment position.
A second aspect of the present invention is the method of segmenting the substrate with the metal film according to the first aspect, wherein a curvature radius of an end portion of an edge of the breaking bar is 5 μm to 25 μm.
A third aspect of the present invention is the method of segmenting the substrate with the metal film according to the second aspect, wherein the predetermined segment position is defined in a plurality of positions at a predetermined interval d1, the first break step and the second break step are performed in an equivalent position from each of a pair of holding parts separated from each other in a horizontal direction in a state where the pair of holding parts support the substrate with the metal film from below, and a remote distance d2 of the pair of holding parts is set to satisfy: d2=0.5d1 to 1.25d1 in the first break step; and d2=1.0d1 to 1.75d1 in the second break step.
A fourth aspect of the present invention is the method of segmenting the substrate with the metal film according to any one of the first to third aspects, wherein the scribe step, the first break step, and the second break step are performed in a state where an adhesive tape is attached to the metal film, and in the first break step, the portion other than the metal film is segmented and a fold line is formed in a position corresponding to the predetermined segment position in the metal film and the adhesive tape.
A fifth aspect of the present invention is the method of segmenting the substrate with the metal film according to any one of the first to fourth aspects, wherein the first break step is performed in a state where the substrate with the metal film is in a vertically reverse posture from a case of the scribe step, and the second break step is performed in a state where the substrate with the metal film is in a vertically reverse posture from a case of the first break step.
According to the first to fifth aspects of the present invention, the substrate with the metal film can be preferably segmented without the occurrence of the peeling of the metal film.
<Semiconductor Device Substrate>
The substrate 1 is a single crystal substrate made of SiC or Si or a polycrystalline substrate made of ceramic, for example. A material, a thickness, and a plane size thereof are appropriately selected and set in accordance with a type, a purpose of use, and a function of a semiconductor device to be manufactured, for example. Examples of the base material 1 include an SiC substrate having a thickness of approximately 100 to 600 μm and a diameter of 2 to 6 inches, for example.
The device pattern 2 is a part mainly relating to a development of a function and characteristics in a semiconductor device to be manufactured and including a semiconductor layer, an insulating layer, and an electrode, for example. A specific configuration is varied in accordance with a type of a semiconductor device, however, assumed in the present embodiment is a case where the device pattern 2 is made up of a thin film layer 2a formed on a whole one main surface of the base material 1 and an electrode 2b partially formed on an upper surface of the thin film layer 2a. Herein, the thin film layer 2a may be made up of a single layer or multilayer, and also the electrode 2b may be a single-layered electrode or a multilayered electrode. Also applicable is a configuration that the base material 1 is partially exposed instead of a configuration that the thin film layer 2a covers a whole surface of the base material 1. Alternatively, a plurality of electrodes 2b may be provided on one unit pattern.
A material and a size of the thin film layer 2a and the electrode 2b are appropriately selected and set in accordance with a type, a purpose of use, and a function of a semiconductor device to be manufactured, for example. For example, examples of the material of the thin film layer 2a include nitride (for example, GaN and AlN), oxide (for example, Al2O3, SiO2), an intermetallic compound (for example, GaAs), and an organic compound (for example, polyimide), for example. The material of the electrode 2b may be appropriately selected from a general electrode material. For example, examples of the material of the electrode 2b include metal such as Ti, Ni, Al, Cu, Ag, Pd, Au, and Pt and an alloy thereof. A thickness of each of the thin film layer 2a and the electrode 2b is smaller than that of the base material 1.
The metal film 3 is assumed to be used mainly as a back surface electrode. However, in the method according to the present embodiment, the metal film 3 is formed on the other whole main surface of the base material 1 (more specifically, over at least the predetermined segment position). Also the metal film 3 may be a single-layered film or a multilayered film in the manner similar to the electrode 2b, and a material thereof may also be appropriately selected from a general electrode material such as metal of Ti, Ni, Al, Cu, Ag, Pd, Au, and Pt and an alloy thereof. A thickness of the metal film 3 may be normally smaller than that of the base material 1.
In the present embodiment, the substrate 10 having the above configuration is segmented in the thickness direction in a predetermined segment position P at a predetermined interval in a predetermined direction at least in a plane. The predetermined segment position P is considered as a virtual surface along the thickness direction of the substrate 10. Additionally, the predetermined segment position may be determined at an appropriate interval also in a direction perpendicular to the direction described above to obtain a semiconductor device having a rectangular shape in a plan view.
<Scribe Process>
Sequentially described hereinafter is a specific content of a segmenting process performed on the substrate 10 in the segmenting method according to the present embodiment. Firstly, the scribe process is performed on the substrate 10. The scribe process performed in the present embodiment is similar to a conventional general scribe process.
In the present embodiment, the scribe process is performed using a scribe device 100. The scribe device 100 includes a stage 101 on which an object to be scribed is disposed and a scribing wheel 102 scribing the object to be scribed from above.
The stage 101 has a horizontal upper surface as a mounted surface, and is configured to be capable of suction-fixing the object to be scribed disposed on the mounted surface using a suction means not shown in the drawings. The stage 101 can perform a biaxial movement operation and a rotational operation in a horizontal plane using a drive mechanism not shown in the drawings.
In the meanwhile, the scribing wheel 102 is a disk-shaped member (a scribing tool) having a diameter of 2 mm to 3 mm with an edge 102e having an isosceles triangle shape in a cross-sectional view. At least the edge 102e is formed of diamond. An angle (a knife angle) δ of the edge 102e is preferably 100° to 150° (for example, 110°). The scribing wheel 102 is rotatably held by a holding means, not shown in the drawings, provided to be able to go up and down in a vertical direction over the stage 101 in a vertical plane parallel to one horizontal movement direction of the stage 101.
A known device can be applied to the scribe device 100 as long as it includes the function described above.
The scribe process is performed after a dicing tape (an expansion tape) 4 having an adhesion property and a plane size larger than a plane size of the substrate 10 is attached to a metal film 3 side of the substrate 10 as illustrated in
Specifically, as illustrated in
After the substrate 10 is fixed, the stage 101 is appropriately operated, thus a positioning is performed so that the predetermined segment position P and a rotational surface of the scribing wheel 102 are located in the same vertical plane. The positioning is performed to position the edge 102e of the scribing wheel 102 over a device pattern end portion Pa of the predetermined segment position P as illustrated in
When the positioning is performed, the scribing wheel 102 is moved down to a vertically lower side until the edge 102e is pressingly contacted by the device pattern end portion Pa of the predetermined segment position P by the holding means not shown in the drawings as indicated by an arrow AR1 in
A load (a scribe load) applied from the edge 102e to the substrate 10 in the pressing contact and a movement speed (a scribe speed) of the stage 101 may be appropriately defined in accordance with a material and thickness, for example, of a constituent material of the substrate 10, especially of the base material 1. For example, when the base material 1 is made of SiC, the scribe load needs to be approximately 1N to 10N (for example, 3.5N), and the scribe speed needs to be 100 mm/s to 300 mm/s (for example, 100 mm/s).
When the pressing contact is performed, the scribing wheel 102 is moved in an extension direction (a direction vertical to the drawing in
When the pressing contact, rotation, and movement of the scribing wheel 102 proceeds along the device pattern end portion Pa in the above manner, a scribe line SL is formed on the device pattern 2 side of the substrate 10 as illustrated in
The vertical crack VC is formed in all of the predetermined segment positions P by the scribe process.
<First Break Process>
A first break process is subsequently performed on the substrate 10 in which the vertical crack VC is formed as described above.
In the present embodiment, the first break process is performed using a break device 200. The break device 200 includes a holding part 201 on which an object to be broken is disposed and a breaking bar 202 performing the break process.
The holding part 201 is made up of a pair of unit holding parts 201a and 201b. The unit holding parts 201a and 201b are provided to be separated from each other with a predetermined distance (remote distance) d2 in a horizontal direction, and horizontal upper surfaces thereof having the same height position are used as mounted surfaces on which the object to be broken is disposed as a whole. In other words, the object to be broken is disposed on the holding part 201 in a state of being partially exposed to a lower side. The holding part 201 is made of metal, for example.
The holding part 201 enables an operation of moving the pair of unit holding parts 201a and 201b close to and away from each other in a predetermined direction (a back-and-forth direction of the holding part) in a horizontal plane. That is to say, the remote distance d2 can be changed in the break device 200. In
Furthermore, the holding part 201 enables an alignment operation on the object to be broken disposed on the mounted surface in the horizontal plane using a drive mechanism not shown in the drawings.
The breaking bar 202 is a plate-like member made of metal (for example, super hard alloy) with an edge 202e having an isosceles triangle shape in a cross-sectional view extending in a blade direction.
More specifically, a foremost end portion of the edge 202e has a minute curved surface having a curvature radius of approximately 5 μm to 30 μm (for example, 15 μm). Also the curvature radius is smaller than a curvature radius of the breaking bar generally used in a conventional break process, that is 50 μm to 100 μm.
The breaking bar 202 is provided to be able to go up and down in a vertical direction in a vertical plane vertical to the back-and forth direction of the holding part by a holding means not shown in the drawings over a middle position between (an equivalent position from) the pair of unit holding parts 201a and 201b in the back-and-forth direction of the holding part.
The first break process using the break device 200 having the configuration described above is performed, as illustrated in
Specifically, as illustrated in
When the plurality of the predetermined segment positions P are defined at the predetermined interval (pitch) d1 as is the case for the present embodiment, the substrate 10 is disposed on the holding part 201 in a state where the pair of unit holding parts 201a and 201b are located so that the remote distance d2 is equal to the interval (pitch) d1 of the predetermined segment position P in the substrate 10. The interval between the pair of unit holding parts 201a and 201b is smaller in this condition than that in a condition of d2=1.5d1 (d2 is 3/2 times the value of d1) applied in the general break process. In the actual process, d2 needs to be within a range satisfying d2=0.5d1 to 1.25d1.
After the substrate 10 is disposed, the drive mechanism is appropriately operated to position the substrate 10. Specifically, the extension direction of the predetermined segment position P of the substrate 10 in which the scribe line SL and furthermore, the vertical crack VC is provided in the scribe process is made to coincide with the blade direction of the breaking bar 202. The positioning is performed to position the edge 202e of the breaking bar 202 over a metal film end portion Pb of the predetermined segment position P as illustrated in
When the positioning is performed, the breaking bar 202 is moved down to a vertically lower side so that the edge 202e is directed toward the metal film end portion Pb of the predetermined segment position P (more specifically, an upper surface of the dicing tape 4) as indicated by an arrow AR2 in
The breaking bar 202 is further moved down a predetermined distance after the edge 202e comes in direct contact with the metal film end portion Pb of the predetermined segment position P. That is to say, the breaking bar 202 is pressed into the substrate 10 at a predetermined pressing amount. The pressing amount preferably ranges from 0.05 mm to 0.2 mm (for example, 0.1 mm).
Then, as illustrated in
However, the metal film 3 is not separated at this time, but is only bent by the pressing of the edge 202e. That is to say, a bending part B is formed in the metal film 3 and the dicing tape 4 located between the edge 202e and the metal film 3 at the time of pressing the breaking bar 202.
Subsequently, as indicated by an arrow AR4 in
The first break process performed in the manner described above is intended to reliably generate the division in the base material 1 and the device pattern 2 and reliably form the bending part B which can be visually recognized as the fold line in the metal film 3. In the first break process, as the condition for preferably achieving these configurations, the remote distance d2 between the pair of unit holding parts 201a and 201b is equal to the interval d1 of the predetermined segment position P and the curvature radius of the foremost end portion of the edge 202e is 5 μm to 30 μm, differing from the general break process. The knife angle θ is preferably 5° to 30°.
<Second Break Process>
After the division of the base material 1 and the device pattern 2 and the formation of the bending part B in the metal film 3 and the dicing tape 4 are performed by the first break process, a second break process is performed. The second break process is performed using the break device 200 in the manner similar to the first break process.
In the second break process, as illustrated in
After the substrate 10 is disposed, the drive mechanism is appropriately operated to position the substrate 10. Specifically, the extension direction of the segmented surface D and the bending part B is made to coincide with the blade direction of the breaking bar 202. At this time, the bending part B which can be visually recognized in the metal film 3 can be effectively used as an indication of the alignment. When the positioning is performed, the edge 202e of the breaking bar 202 is located over an upper end portion of the segmented surface D which has originally been the device pattern end portion Pa of the predetermined segment position P as illustrated in
When the positioning is performed, the breaking bar 202 is moved down to a vertically lower side so that the edge 202e is directed toward the device pattern end portion Pa of the predetermined segment position P (more specifically, an upper surface of the protection film 5) as indicated by an arrow AR5 in
The breaking bar 202 is moved down until the edge 202e is pressed into the device pattern 2 via the protection film 5 at a predetermined pressing amount as illustrated in
The pressing amount in the second break process preferably ranges from 0.02 mm to 0.1 mm (for example, 0.05 mm) which is approximately half the length of the pressing amount in the first break process. The pressing amount is set to prevent the occurrence of damage due a contact of the two segmented portions. The condition satisfying d2=1.5d1 is intended to preferably segment the metal film 3 in the bending part B even at such a small pressing amount.
After the second break process is finished, as indicted by arrows AR7 in
<Comparison with Conventional Method>
The conventional segmenting process indicates herein that after the scribe process in the scribe device 100 is performed in the manner similar to that in
In this case, as indicated by an arrow AR8 in
In contrast, when the method according to the present embodiment is applied, as illustrated in
As described above, according to the present embodiment, the segmentation of the semiconductor device substrate in which the device pattern is formed on one main surface of the base material and the metal film is formed on the other main surface of the base material can be preferably performed without the occurrence of the peeling of the metal film when the segmentation is performed by the combination of the scribe process and the break process.
<Modification Example>
In the embodiment described above, the scribe process is performed using the scribing wheel, however, the scribe line may be formed using a tool, such as a diamond point, other than the scribing wheel as long as the formation of the scribe line and the extension of the crack are preferably achieved.
The vertical crack VC is already formed in the base material 1 and the bending part B is already formed in the metal film 3 in the first break process, thus a breaking bar having the knife angle θ and the curvature radius in the end portion similar to that in the conventional segmenting process may also be used in the second break process.
The break device used in the first break process and the second break process includes the holding part 201 made up of the pair of unit holding parts 201a and 201b separated from each other with the predetermined distance in the horizontal direction, however, a break device including a holding part made up of an elastic body having contact with the whole surface of the substrate and holding the substrate may also be used instead. Also in this case, the pressing amount in the first break process preferably ranges from 0.05 mm to 0.2 mm (for example, 0.1 mm) and the pressing amount in the second break process preferably ranges from 0.02 mm to 0.1 mm (for example, 0.05 mm) which is approximately half the length of the pressing amount in the first break process.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-207764 | Oct 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/038482 | 10/16/2018 | WO | 00 |
