JP7311584B2 - Semiconductor chip manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing semiconductor chips characterized by singulation of a semiconductor wafer. In particular, the present invention is suitably applied to a manufacturing method for cutting out power devices such as IGBTs and FETs from a substrate having SiC or GaN-based hexagonal crystal orientation.

As inventions for singulating semiconductor wafers, there are a full-cut method (Patent Documents 1 and 2) in which semiconductor elements are separated at once by laser light or a dicer, and a two-stage full-cut method (Patent Documents 3 and 3). 4), or a scribe-and-break method (Patent Document 5), in which a groove-shaped scribe line is pressed from the opposite side to break it, and the like have been proposed. It should be noted that it is also possible to provide a slice line by an etching process, but the process time (the etching rate of SiC is, for example, about 1 μm/min) is long and the production line is complicated, so it is excluded from the following discussion. be.

JP 2017-228660 A JP 2016-100412 A JP 2018-113288 A JP 2013-161944 A JP-A-62-108007 JP 2014-068031 A

By the way, power devices, which have been widely used in recent years, are heated to high temperatures during operation and undergo repeated thermal expansion. Here, the bending strength is evaluated, for example, by a three-point bending test based on JISR1601, and specifically, it is desired to exceed 500 MPa, preferably 1000 MPa or more.

However, with respect to each of the above inventions, for example, when a dicer is applied to a hard substrate such as SiC, (a) the grinding wheel of the dicer is greatly worn, (b) the processing speed is slow, and (c) water cooling is required. Therefore, there is a problem that it cannot be used depending on the material.

On the other hand, in each of the above inventions, even if a laser beam is used, minute cracks inevitably occur during scribing, so there is a limit to the bending strength. For example, when the scribe-and-break method is adopted, high bending strength cannot be exhibited in a three-point bending test in which the scribe line is arranged below. Further, when the full cut method or the two-step full cut method is adopted, there is a limit to the bending strength regardless of which side is arranged downward.

FIG. 5 is a photograph of a cross section when the scribe-and-break method is adopted, and the cross section when the semiconductor wafer is pressurized perpendicularly to the front surface of the semiconductor wafer at once in order to widen the straight laser processing line from the back side at once. is shown.

In the scribe-and-break method, a semiconductor wafer is pressed in its thickness direction and divided at once, so that a first region A, which is a laser processing line, and a second region B, in which cracks spread in multiple directions from the first region A, are formed. , and the cleaved regions C formed in multi-stepped planes that are hardly flush with each other, and the bending strength is limited.

Here, an invention has also been proposed in which a modified portion is provided inside the substrate by laser light without damaging the front and back surfaces of the wafer (Patent Document 6). In addition, it is also described that in a substrate having a hexagonal crystal structure, a cutting starting point region (planned cutting line) is formed in a direction along the A plane or the M plane with the C plane as the main plane (paragraph 0040).

However, in the present invention, the laser focal points P must be formed at a fairly close pitch (see FIG. 5 of Patent Document 6), and the actually formed molten processing region 13 (line to be cut) is , must be continuous in a bar shape with a certain thickness (see FIG. 12 of Patent Document 6).

This scheduled cutting line is, in short, nothing but a scribe line provided inside the substrate. Starting from this scheduled cutting line as a starting point, as in the scribe and break method, even if the substrate is divided at once, a flush cleavage plane is realized. It is not possible. In fact, as can be seen from FIG. 12 of Patent Document 6, the cut surface has minute unevenness similar to that in the case of adopting the scribe and break method (see comparison with FIG. 4 of the present application).

In addition, according to the present invention, when the wafer is to be divided by stress, it is necessary to pressurize the back surface of the wafer in the opposite direction following the pressurization step directed to the front surface of the wafer, which is complicated.

The present invention has been made in view of the above problems, and a power device having excellent bending strength can be cut out from a semiconductor wafer by forming a clean cleaved surface by applying pressure in an inclined direction from the starting point of division. It is an object of the present invention to provide a method of manufacturing a semiconductor chip that can

In order to achieve the above object, a semiconductor chip manufacturing method according to the present invention is a manufacturing method for forming cleaved planes on the four end surfaces of a semiconductor chip, which is a rectangular power element that thermally expands during operation. A first step of intermittently providing cleavage starting points on the front surface side of the semiconductor wafer in the vicinity of four corners surrounding one or more semiconductor chips on the wafer, corresponding to the arrangement pitch of the semiconductor chips, to specify pressing lines. Then, the semiconductor wafer is turned upside down, and in a state in which both sides of the pressing line are supported, a pressing blade whose tip line forms a predetermined inclination angle with respect to the back surface of the semiconductor wafer is directed from the back surface of the semiconductor wafer to the cleavage starting point. to rotate the positional relationship between the second step of pushing the cleavage opening in the direction of the tip line and the push blade by 90° from the state of the second step and supporting both sides of the pressing line, a third step of pushing the cleavage opening in the direction of the tip line by lowering a pushing blade whose tip line forms a predetermined inclination angle with respect to the back surface of the semiconductor wafer from the back surface of the semiconductor wafer toward the cleavage starting point; to form a cleaved facet that is flush with no level difference even with a microscope magnification of 100 times in a region of 1/2 or more of the total area of the end face in the center of the end face of the semiconductor chip.

In the present invention, "four corners surrounding one or more semiconductor chips" include not only the four corners of each semiconductor chip in a plurality of semiconductor chips, but also the four corners of the entire plurality of semiconductor chips. It is a concept. Normally, in one semiconductor wafer, the crystal plane of the substrate layer is aligned over a plurality of semiconductor chips, so if the cleavage opening is advanced from one cleavage starting point, a straight cleavage plane is formed over a plurality of semiconductor chips. be able to.

The second step preferably includes, as in the embodiment, (1) disposing, for example, two plate members under the semiconductor wafer and forming opening grooves at both shoulder edges of the semiconductor wafer. A semiconductor wafer is placed on a mounting table provided with an opening groove that allows deformation. (2) A blade-like pressing metal fitting (push blade) is placed above the semiconductor wafer so that it is perpendicular to the wafer surface and the tip of the blade is slanted. (3) By moving the pressing blade in the vertical direction, a bending stress is applied to the semiconductor wafer by both shoulder edges of the plate material, and the bending deflection exceeds the critical stress, so that the stress concentration line is formed from the cleavage starting point. Cleavage fracture along the

Further, the cleavage starting point is typically cross-shaped or cut-shaped. However, the cross-sectional shape on the tip side in the cleavage direction is preferably a keel shape that gradually becomes shallower toward the bow.

The idea of the inventor of the present invention is as follows. When deep line scribing is performed and division is performed by opening in the vertical direction to the upper and lower surfaces of the wafer, many vertical step lines can be seen. The individual step lines are the interlayer steps of the cleaved plane. The inter-layer step is caused by the fact that the starting point of the opening at the bottom of the line scribe is displaced by several layers of the crystal layer=cleavage plane layer, and each layer serves as the starting point of the opening to expose a different cleavage plane.

This inter-layer step is not preferable in a semiconductor chip because, when the device chip functions, frequent heat release occurs due to the passage of current, and this stress is applied to stress concentration points due to thermal expansion. That is, when there are many stress concentrations with different crystal layers = cleaved layers, there is a high probability that the opening direction to the adjacent concentration point is a different crystal plane (direction with a different angle of 15 degrees or more), and when the stress is applied, This is because it is considered that the crack progresses to the inside, which is not parallel to the end face, and easily leads to fracture.

In the case of a thin rectangular block such as a chip, the direction of stress concentration is greatly affected by the end face and the starting point of the opening of the ridge formed by the end face because the expansion and contraction of the surface is the largest. In addition, it concentrates toward the center rather than the four corners of the block. Therefore, when forming the side surface of the chip, if the starting point of the opening of the cleavage is positioned horizontally instead of vertically, the cleavage can be opened laterally so as to form a single layer.

Although the method for manufacturing a semiconductor chip has been described above, the present invention can also be positioned as a method for dividing a semiconductor wafer. In this case, a semiconductor wafer in which a plurality of element chips, each having a semiconductor layer formed on a single crystal substrate, are arranged vertically and horizontally is cut out from the semiconductor wafer, and the dividing method is one of the front and back surfaces of the semiconductor wafer. a first step of preliminarily determining a first pressing line and a second pressing line on a surface opposite to the dividing starting surface by forming a processing groove on the dividing starting surface so as to surround the element chip;
a second step of fixing the semiconductor wafer to a mounting table having a linear groove longer than the maximum distance in the vertical and horizontal directions of the semiconductor wafer, with the dividing starting surface facing downward;
With the first pressing line aligned with the center of the width of the straight groove, the pressing blade is pressed along the first pressing line, and the pressing blade and both shoulders of the straight groove apply a cleaving stress to the semiconductor wafer. a third step of advancing the cleaved surface starting from the processed groove along the first pressing line;
With the second pressing line aligned with the center of the width of the straight groove, the pressing blade is pressed along the second pressing line, and the cutting stress is exerted on the semiconductor wafer by both shoulders of the pressing blade and the straight groove. A fourth step of advancing the cleaved surface starting from the processed groove along the second pressing line by adding
The machined grooves defining at least one of the first pressing line and the second pressing line are intermittently formed corresponding to the arrangement pitch of the element chips, and the pressing blade has the It is characterized in that it is pressed against a semiconductor wafer in an inclined state.

In the present invention, as a first feature, the processing grooves defining at least one of the first pressing line and the second pressing line are intermittently formed at intervals corresponding to the arrangement pitch of the element chips to be cut out. there is Therefore, in a three-point bending test in which the cut-out element chip is placed with the cut-off surface facing downward, it exhibits superior bending strength compared to element chips cut out by the full-cut method or the scribe-and-break method. Demonstrate. That is, in a three-point bending test in which a bending stress is applied to a machined surface provided with intermittent machined grooves, it exhibits a bending strength superior to that of an element chip cut out by the scribe-and-break method.

The machined grooves may be formed in the shape of spots, but are preferably formed in the shape of broken lines. In the configuration in which the machined grooves are formed in the shape of broken lines, it is particularly preferable to form the cut-like machined grooves at the four corners of the element chip. The processed groove preferably has a keel-shaped cross-sectional shape on the tip side in the cleavage direction, and the depth of the processed groove gradually decreases toward the bow.

In any case, it is preferable to form the broken-line processing grooves with a length of 200 μm or more, and more preferably, one or more grooves may be provided in the vicinity of the four corners of one or a plurality of element chips.

In the present invention, the depth of the processed groove is not particularly limited, but it is preferable to form the processed groove to a depth reaching the single crystal substrate beyond the semiconductor layer. In this case, since the semiconductor layer is sufficiently thin, the semiconductor layer is also cut along with the cleaved surface of the single crystal substrate.

A second feature of the present invention resides in the fact that an inclined presser blade is pressed against the surface opposite to the cutting starting surface on which the grooves are formed. Here, the inclination angle of the pressing blade with respect to the semiconductor wafer is not particularly limited. is.

Then, in the third step and the fourth step, the slanted pressing blade is pressed along a first pressing line and a second pressing line (hereinafter collectively referred to as pressing lines) formed on the surface opposite to the splitting starting surface. be done. In this pressing state, the pressing line is aligned with the center of the width of the linear groove of the mounting table, so that the semiconductor wafer is supported by both shoulders of the linear groove and slightly inclined.

Therefore, the stress is concentrated so as to expand the outermost processed groove, which has the largest deflection. Based on this stress, the semiconductor wafer breaks in the thickness direction starting from the outermost processed groove, and the Alternatively, a small number of microcracks progress in the direction of inclination and reach the cleavage plane.

In the third step and the fourth step, the cleaved surface gradually advances obliquely upward corresponding to the tip line of the pushing blade based on the pressing force of the pushing blade in the inclined state. A split surface is formed by a clean cleavage plane.

In order to realize such an operation, it is preferable to move the pushing blade at a speed of about 3 mm/S to 10 mm/S by decelerating it until it contacts the wafer after smoothly lowering the pushing blade. In this case, the moving direction of the pushing blade is simply the direction orthogonal to the surface of the semiconductor wafer (vertical drop), but it is also preferable to set it to the projecting direction of the inclined pushing blade (inclined drop).

The thickness of a semiconductor wafer is generally about 350 μm to 100 μm, with a maximum thickness of 500 μm. A semiconductor wafer having such a thickness is supported by both shoulders of the straight groove, and a cleaving stress in the direction of inclination is applied to the central position of the groove. will proceed smoothly.

On the other hand, when the scribe-and-break method or the structure of Prior Document 6 is employed, many cracks progress at once in the plate thickness direction perpendicular to the wafer surface, so a cleaved facet that is flush cannot be formed.

In the present invention, although the maximum distance in the vertical and horizontal directions of the semiconductor wafer is not limited, it is generally about 1 inch to 6 inches in terms of diameter, typically about 3 inches. Therefore, the minimum length of the linear groove of the mounting table is defined according to the above dimensions.

In the present invention, the single crystal substrate is not particularly limited as long as it uses a single crystal in which the direction of the crystal axis is aligned in any part, and may be silicon (Si) or sapphire, but is preferably silicon carbide (SiC ) and the Gallium Nitride (GaN) family with hexagonal crystal orientation. Of these, silicon carbide (SiC) is classified into 2H, 4H, 6H, 8H, 10H, etc., and 4H hexagonal SiC is preferably used.

Also, the element chip according to the present invention is not particularly limited, but it is preferable to apply the present invention to a power device in which intense thermal history is repeated. Power devices include IGBTs (Insulated Gate Bipolar Transistors), MOSFETs (metal-oxide-semiconductor field-effect transistors), and PiN diodes in which an I layer (Intrinsic Layer) is sandwiched between a P layer and an N layer. A suitable example can be given.

In the present invention, there are generally a plurality of first pressing lines and second pressing lines. Then, a plurality of N pressing lines may be pressed by N pressing blades, and the N pressing lines may be collectively processed, or each pressing line may be processed individually. In any case, the third step and the fourth step are performed a plurality of times while changing the positional relationship between the semiconductor wafer and the linear grooves due to the narrow spacing between the element chips.

According to the above-described present invention, since a unique cutting procedure is employed, it is possible to form a clean and flush cleavage plane, and to cut out and manufacture a power device having excellent bending strength.

It is drawing explaining a processing procedure about the parting method of an Example. It is drawing explaining a processing groove. FIG. 4 is a perspective view showing the positional relationship between a pressing blade and a semiconductor wafer; It is a photograph showing a cleavage plane. It is a cross-sectional photograph of an element chip when the scribe-and-break method is adopted.

Examples will be described in more detail below. In the following description, a minus sign "-" preceding a number in a crystal lattice plane means a bar.

The size of a power element driven by a large current is generally assumed to be about 1 mm×1 mm to 10 mm×10 mm. This size is assumed based on the balance between the maximum allowable current, the amount of heat generated, and the size of the product used.

Therefore, in this embodiment, a width of 4 mm and a length of 7 mm, which is the minimum required for examining the bending strength, were selected. Although not particularly limited, in this example, a semiconductor wafer WAF having a thickness of 350 μm and having a semiconductor layer provided on a silicon carbide single crystal substrate was used.

As shown in FIG. 1(b), this semiconductor wafer WAF is provided with a first orientation flat (orientation flat) OF on its 1-100 plane. A second orientation flat IF is provided on the 11-20 surface.

Here, the silicon carbide single crystal substrate is composed of 4H hexagonal SiC, and as shown in FIG. It has a crystal structure having an A plane. Then, the semiconductor wafer WAF was cut in a first direction perpendicular to the first orientation flat OF and a second direction parallel to the first orientation flat OF to cut out square element chips CHP of about 7×7 mm.

The dividing procedure will be described below with reference to FIG. 1(a). First, the semiconductor wafer WAF is attached to the adhesive sheet SH with the 0001 surface (commonly called Si surface) facing up. This adhesive sheet SH has appropriate elasticity and strength so that the element chips CHP after division can be separated in the expanding process.

Next, in this bonded state, a laser beam having a wavelength of 355 nm, a pulse width of 36 nS, and a laser power of 0.5 W is used to form processing grooves GR having the shape shown in FIG. It was intermittently provided with a depth reaching the substrate (ST1 to ST2). The machined groove GR is cut-like as shown in FIG. 2(d), and the cross-sectional shape on the tip side in the cleavage direction is a so-called keel shape, which gradually becomes shallower toward the bow.

As shown in FIG. 2, the chip size of the element chips CHP to be cut out is about 7 mm×7 mm, and the rupture grooves are formed at intervals of 1/2 or more of the arrangement pitch (Pih, Piv) of the element chips CHP. It will be.

In this embodiment, for the sake of convenience, the processing groove GR was provided on the side of the 0001 plane (commonly known as the Si plane) on which the semiconductor layer was provided, and the Si plane was used as the dividing starting plane. may be provided with a fracture groove. However, when laser light is used, it is a condition that there is no reflective layer for the laser light at the formation location of the processed groove GR, and when the processed groove GR is provided beyond the reflective layer, machining is performed.

Although the sequence of forming the processed grooves GR is not limited at all, in this embodiment, first, the processed grooves GR were intermittently formed over N rows in the first direction, which is the direction perpendicular to the first orientation flat OF (ST1). . By this process, N first pressing lines to be pressed by the pressing blades DV (FIG. 3) are defined on the surface C in the subsequent pressing step.

In the embodiment, since the processing grooves GR are formed at the four corners of the element chips CHP, there are at most N−1 element chips CHP in the second direction.

Next, machined grooves GR having a length of about 2 mm were intermittently formed over M rows in the second direction parallel to the first orientation flat OF (ST2). By this process, M second pressing lines against which the pressing blades DV are pressed in the subsequent pressing step are defined in the second direction of the C surface.

Also in this case, since the processing grooves GR are formed at the four corners of the element chips CHP, there are at most M−1 element chips CHP in the first direction.

Next, a protective tape PR is pressed against the Si surface of the semiconductor wafer WAF and adhered to the adhesive sheet SH on the outer peripheral side of the semiconductor wafer WAF. Then, the semiconductor wafer WAF wrapped with the protective tape PR and the adhesive sheet SH is fixed to the mounting table PL (ST3). The fixed posture is as shown in FIG. 1(e), with the Si surface provided with the processed groove GR facing downward.

Here, in the mounting table PL, for example, a linear groove SP having a horizontal left-right width that is longer than the maximum diameter of the semiconductor wafer WAF and that allows bending deformation of the semiconductor wafer WAF is formed ( See FIG. 1(e)). In this embodiment, one pressing blade DV is used to process each pressing line, but a plurality of pressing blades DV may be used simultaneously to process a plurality of pressing lines at once. .

In any case, in the process of step ST4, the pressing blade DV is slowly lowered along the pressing line while the pressing line to be pressed is positioned at the center position in the width direction of the straight groove SP.

The pressing edge DV is as shown in FIG. 3, and its pressing tip, which is longer than the maximum diameter of the semiconductor wafer WAF and extends in the horizontal direction, is inclined at an angle of inclination θ and brought into contact with the pressing line. In the example, the inclination angle θ of the pressing blade DV is θ=Tan−1 (50 μm/110 mm).

Then, the pushing blade DV with the inclination angle θ was lowered vertically at a speed of 15 mm/s, and then lowered slowly (ST4). FIGS. 1(d) and 1(e) illustrate the cutting process in which the pressing blade DV is slowly lowered, showing a side view (d) and a front view (e).

As shown in the figure, the machined groove GR is intermittently arranged on a straight line on the opposite surface of the pressing line on which the pressing blade DV abuts. Then, when the push blade DV descends, the stress concentrates on the outermost processed groove GR having the largest deflection, so that the semiconductor wafer is broken in the plate thickness direction starting from the outermost processed groove GR. Alternatively, a small number of microcracks progress in an inclined direction (slightly upper right direction in the figure) and reach the cleavage plane.

After that, based on the pressing force of the pushing blade DV in the inclined state, the cleaved surface gradually progresses obliquely upward (see FIG. 1(d)) corresponding to the tip line of the pushing blade DV, so that the cleaved surface is flush. A split surface is formed by a clean cleavage plane of . The amount of descent of the push blade DV is about 60 μm, and the processing time for the single line of cutting is within 1.3 seconds from the start of contact.

In this manner, for example, when a line of dividing processing is completed in the first direction, the position of the semiconductor wafer WAF is shifted, and another pressing line is processed (ST5).

Then, when all the dividing processes in the first direction are completed, the semiconductor wafer WAF is rotated by 90 degrees and rearranged on the mounting table PL (ST6). Next, the division processing for the second direction is executed by executing the processing similar to the processing of steps ST4 to ST5 for the second direction (ST7, ST8).

Finally, the element chips singulated through the expander that spreads the adhesive sheet in four directions and the process are transferred to subsequent processing (ST9).

FIG. 4 is a photograph showing a cleaved cross section (M plane) in the second direction of the cut element chip, showing the chip center and the chip end. As shown in the figure, a transitional surface is generated between the processed groove and the cleaved surface at the chip end, but a clean cleaved surface that is flush with the chip appears at the center of the chip.

In the three-point bending test on the long side (7 mm), the bending strength when the splitting starting surface with intermittent processing grooves is placed on the upper surface always maintains 1815 Mpa or more, while the splitting starting surface is on the lower surface. Even in the case of 1,103 to 1,814 MPa, an excellent bending strength was obtained.

In addition, the fulcrum interval L = 5.7 mm, the sample width W = 7 mm, the sample thickness t = 0.34 mm, the bending strength δd for the load X, δd = 3 * X * L / (2 * W * t2 ).

By the way, even if it is a continuous groove (line groove) instead of an intermittent processed groove, as long as it is cleaved in an oblique direction, the bending strength when the division starting surface on which the line groove is provided is the upper surface is 1172 ~ It was 1814 Mpa, and when the splitting origin surface was on the bottom surface, the bending strength was 620 to 975 Mpa. From this result, it is confirmed that the effect of the present invention, in which intermittent processed grooves are provided, is particularly effective in terms of the bending strength δd when the splitting origin surface is the lower surface.

Although the embodiments of the present invention have been described in detail above, the specific description does not particularly limit the present invention. In particular, the machined groove GR is not limited to the cross shape shown in FIG. 2(a), and may be a straight cut shape shown in FIG. 2(b). Also in this case, the cross-sectional shape of the machined groove GR is a so-called keel shape, and the tip side of the machined groove GR in the cleavage direction gradually becomes shallower toward the bow.

Also, in the embodiment, one or more processed grooves are provided near the four corners of each semiconductor chip, but the present invention is not limited at all. For example, less than N cleavage starting points may be intermittently provided for a plurality of N semiconductor chips provided on one semiconductor wafer. Furthermore, a single cleavage starting point may be provided at an appropriate position (for example, the base end) of one pressing line of one semiconductor wafer.

CHP Element chip WAF Semiconductor wafer SH Adhesive sheet PL Mounting table

Claims (7)

A manufacturing method for forming cleavage planes on the four end surfaces of a semiconductor chip, which is a rectangular power element that thermally expands during operation,
First , a pressing line is specified by intermittently providing cleavage starting points corresponding to the arrangement pitch of the semiconductor chips on the surface side of the semiconductor wafer near four corners surrounding one or more semiconductor chips on the semiconductor wafer. process and
While the semiconductor wafer is turned upside down and both sides of the pressing line are supported, a pressing blade whose tip line forms a predetermined inclination angle with respect to the back surface of the semiconductor wafer is lowered from the back surface of the semiconductor wafer toward the cleavage starting point. a second step of pushing the cleave opening in the direction of the tip line by causing the
Rotating the positional relationship with the pushing blade by 90° from the state of the second step and supporting both sides of the pushing line, the pushing blade having a tip line forming a predetermined inclination angle with respect to the back surface of the semiconductor wafer, a third step of pushing the cleavage opening in the direction of the tip line by lowering the semiconductor wafer from the back surface toward the cleavage starting point ;
1. A method of manufacturing a semiconductor chip, comprising the steps of: forming a cleaved facet that is flush with no level difference even under a microscope magnification of 100 times in a region of 1/2 or more of the total area of the end face of the semiconductor chip. 2. The method of manufacturing a semiconductor chip according to claim 1, wherein said pressing blade is formed longer than the maximum diameter of the semiconductor wafer. 2. The method of manufacturing a semiconductor chip according to claim 1, wherein said pressing blade moves at a speed of 3 mm/S to 10 mm/S. 4. The method of manufacturing a semiconductor chip according to claim 1, wherein the cleavage starting point is a working flaw reaching the semiconductor single crystal substrate. 5. The method of manufacturing a semiconductor chip according to claim 4, wherein the processing damage has a cut-like shape in a plan view, and has a keel shape that gradually becomes shallower toward the bow on the tip side in the cleavage direction. A device used in the manufacturing method according to any one of claims 1 to 5,
A semiconductor chip manufacturing apparatus having a mechanism for applying a three-point bending stress load, and configured such that when a pressing blade at the center of the three points is pushed down, the point to be pressed advances sequentially along the pressing line. 7. The semiconductor chip manufacturing apparatus according to claim 6, wherein said pressing blade is pressed vertically or obliquely downward along said pressing line .

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