JPH0766914B2 - Manufacturing method of power semiconductor device and core drill for cutting semiconductor chip - Google Patents

Description

The present invention relates to a method for manufacturing a power semiconductor device in which a semiconductor chip having a beveled outer peripheral portion is separated from a semiconductor wafer by a core drill, and a semiconductor chip is separated. The present invention relates to the structure of a core drill for dividing a semiconductor chip used.

[Conventional technology]

Since a power semiconductor device such as a power thyristor generally requires a large current carrying capacity, a semiconductor chip used in this power semiconductor device requires a high voltage blocking ability, and a so-called mesa-type passivation structure may be adopted. Many. In such a semiconductor chip, since the surface of the PN junction is located on the side surface of the semiconductor chip, it was manufactured by rotating the semiconductor chip and beveling the side surface. A method of manufacturing this type of semiconductor chip will be described with reference to FIGS.

FIG. 5 is a cross-sectional view showing a conventional semiconductor chip used in a power thyristor, FIG. 6 is a perspective view showing a state of a large-diameter substrate on which a semiconductor chip portion is formed, before cutting, and FIG. FIG. 6 is a perspective view showing a state where a large-diameter substrate is divided into individual semiconductor chips by a core drill. In these figures, 1 denotes a semiconductor chip, and this semiconductor chip 1
The PE layer 1a, the NB layer 1b, the PB layer 1c, the NE layer 1d, and the like are formed on the outer surface of the PE layer, and an inclined surface (beveling surface) is formed on the outer peripheral portion by beveling. Reference numeral 2 denotes a metal heat radiating plate. The metal heat radiating plate 2 is made of a molybdenum plate or the like having a small difference in coefficient of thermal expansion with respect to a silicon single crystal of a general semiconductor chip 1. The alloy is fixedly attached through the brazing material 3 of FIG. Reference numeral 4 denotes a large-diameter substrate made of a semiconductor wafer used for manufacturing the semiconductor chip 1. The large-diameter substrate 4 is provided with a plurality of semiconductor chip portions 4a through processes such as diffusion and photolithography. Reference numeral 5 is a core drill for dividing the semiconductor chip portion 4a from the large-diameter substrate 4 to obtain the semiconductor chip 1. The core drill 5 is opened to have a size substantially equal to the outer diameter of the semiconductor chip 1 and has a cylindrical shape as a whole. The grinding cylinder 5a is formed, and the shank 5b is connected to a driving device (not shown) and is rotated together with the grinding cylinder 5a.

Next, a procedure for manufacturing the above-described semiconductor chip 1 for a power thyristor will be described. First, as shown in FIG. 6, a plurality of semiconductor chip portions 4a are formed on the large-diameter substrate 4 through processes such as diffusion and photolithography. Next, as shown in FIG. 7, the core drill 5 is pressed from above while rotating to a portion of the large-diameter substrate 4 corresponding to the semiconductor chip portion 4a, and the semiconductor chip 1 is hollowed from the large-diameter substrate 4 by the core drill 5. Thereafter, the metal heat dissipation plate 2 is alloy-fixed to the back surface of the semiconductor chip 1 via the brazing material 3, and the outer peripheral end face of the semiconductor chip 1 is beveled by a sand blasting method, an angle polishing method, or the like to form the semiconductor chip 1 The manufacturing process of is completed. As described above, the electric field strength on the surface of the semiconductor PN junction can be reduced by performing beveling (beveling) on the outer peripheral end surface of the semiconductor chip 1, and a high-voltage power thyristor can be obtained.

As a method of dividing the semiconductor chip 1 from the large-diameter substrate 4, there is a method of using laser light in addition to the use of the core drill 5 as described above.

[Problems to be Solved by the Invention]

However, in the conventional method for manufacturing a power semiconductor device configured as described above, the semiconductor chip 1 must be hollowed out from the large-diameter substrate 4 and then beveled. For this reason, the manufacturing process of the semiconductor chip 1 involves two processes, a hollowing process and a beveling process, which causes a problem of low production efficiency.

[Means for Solving the Problems]

The method for manufacturing a power semiconductor device according to the present invention is divided by a core drill having an inner grinding surface formed to have an inner diameter narrowed toward the base side and an outer peripheral surface having a constant outer diameter at a semiconductor chip dividing portion. Sometimes beveling is done at the same time. Further, the core drill for dividing a semiconductor chip according to the present invention has a grinding cylinder whose one end is opened with an opening size substantially equal to the outer diameter size of the semiconductor chip and the other end is connected to a driving device. In the peripheral part, an inner grinding surface inclined at an angle corresponding to the beveling surface of the semiconductor chip is provided by narrowing the inner diameter from the opening side toward the base side, and the outer diameter at the semiconductor chip dividing part in this grinding cylinder is set. It is constant.

[Work]

According to the method for manufacturing a power semiconductor device of the present invention, since the semiconductor chip can be divided and beveled at the same time, the manufacturing process can be simplified and the semiconductor chip can be manufactured efficiently. Further, when the semiconductor chip cutting core drill according to the present invention is used, the semiconductor chip is beveled by the inner grinding surface such as grinding.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 (a),
This will be described in detail with reference to (b).

FIG. 1 is a cross-sectional view showing a core drill according to the present invention, and FIGS. 2 (a) and 2 (b) are views for explaining the operation of the core drill according to the present invention, in which FIG. FIG. 3B is a sectional view showing a state in which the semiconductor chip is separated from the large-diameter substrate. In these figures, the same or equivalent members as those described in FIGS. 5 to 7 are designated by the same reference numerals, and detailed description thereof will be omitted here. In FIGS. 1 and 2 (a) and (b), 11 is a core drill according to the present invention, and the core drill 11 has a body 13 having a shank 12 connected to a driving device (not shown), and the body 13. And a grinding cylinder 14 for dividing the semiconductor chip which is rotated together with 13. The body 13 is integrally formed of aluminum or the like, and has a water passage hole through which cooling water flows in its axial center portion.
13a is drilled. The grinding cylinder 14 is integrally formed with a nickel plate or the like, and diamond abrasive grains (not shown) are bonded to the entire grinding portion. Further, a large diameter portion 14a as a semiconductor chip dividing portion opened with an opening size substantially equal to the outer diameter of the semiconductor chip 1 is provided at one axial end of the grinding cylinder 14, and the large diameter portion 14a is provided at the other end. The body 13 is formed by squeezing the beveling angles α and β of the semiconductor chip 1 from the diameter portion 14a.
A base portion 14b fixed to is provided. The large diameter portion 14a
Has a cylindrical shape with a constant outer diameter. That is,
By being squeezed as described above, an inner grinding surface 14c inclined at an angle corresponding to the beveling angle of the semiconductor chip 1 is provided on the inner peripheral portion of the grinding cylinder 14. The beveling angle α is usually 135 degrees and the angle β is
Is set to 140 degrees, but the angles α and β can be appropriately changed according to the specifications of the thyristor device.

Next, the core drill 11 according to the present invention configured as described above
A procedure for dividing the semiconductor chip 1 by using will be described. First, the core drill 11 is placed on the large-diameter substrate 4 on which a plurality of semiconductor chip portions 4a are formed. Then, while rotating the core drill 11 at 3000 to 5000 rpm, the large-diameter substrate 4
To the large diameter substrate 4 at a processing speed of 5 to 10 μm / sec. Then, as shown in FIG. 2A, as the large-diameter substrate 4 is ground by the large-diameter portion 14a of the grinding cylinder 14, the inner grinding surface 14c bevels the outer peripheral end surface of the semiconductor chip 1. . This hollowing operation is performed while supplying cooling water from the water passage hole 13a of the body 13 to the grinding cylinder 14 at a supply pressure of ² kg / cm ² in an amount of 5 to 10 / min. The semiconductor chip 1 is supported from below by vacuum suction during this hollowing operation. Then, the grinding cylinder 14 penetrates the large-diameter substrate 4, so that as shown in FIG.
Will be separated from the large-diameter substrate 4.

Therefore, when using the core drill 11 according to the present invention,
The dividing work of the semiconductor chip 1 and the beveling work can be performed at the same time.

Further, if some notches are provided at the tip of the grinding cylinder in order to permeate the cooling water and promote the discharge of grinding dust, the hollowing can be carried out smoothly.

Although the thyristor device has been described in the present embodiment, the present invention is not limited to such a limitation, and may be any device as long as a semiconductor chip such as a rectifying element is beveled. Can be applied.

In the above embodiment, an example in which the grinding cylinder 14 is formed of a plate material has been described, but the grinding cylinder 14 can also be formed as shown in FIGS. 3 and 4.

3 and 4 are cross-sectional views showing other embodiments of the core drill. In these figures, the same members as those described in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. In FIG. 3, reference numeral 21 denotes a grinding cylinder of the core drill according to the second embodiment, and the grinding cylinder 21 has a constant outer diameter and its thickness gradually increases from the opening side toward the body 13 side. The inner grinding surface 22 is formed in such a manner that it is inclined at the beveling angles α and β of the semiconductor chip 1 on its inner peripheral portion. By thus forming the wall thickness on the body 13 side to be thicker, the rigidity can be increased as compared with the core drill 11 made of the plate material shown in the above-mentioned embodiment. Further, in FIG. 4, reference numeral 31 denotes a grinding cylinder of the core drill according to the third embodiment. The grinding cylinder 31 is formed in a substantially cylindrical shape like the conventional one and is fixed to the body 13. Reference numeral 32 is a second grinding cylinder for beveling the semiconductor chip 1. This second grinding cylinder 32 has an inner grinding surface 33 inclined at the lower end face with the beveling angles α and β of the semiconductor chip 1. It is provided and is fixed to the inner peripheral side of the grinding cylinder 31 and to the lower side of the body 13 by a mounting screw 34 screwed to the body 13. In the core drill having the third grinding cylinder 32 configured as described above, the second grinding cylinder 32 can be appropriately replaced when the beveling angles α and β are changed or when the beveled portion is worn. .

〔The invention's effect〕

As described above, the manufacturing method for manufacturing a power semiconductor according to the present invention has an inner grinding surface formed by narrowing the inner diameter toward the base side, and an outer peripheral surface having a constant outer diameter at the semiconductor chip dividing portion. Since the beveling is performed at the same time when the semiconductor chip is divided by the core drill, the manufacturing process of the semiconductor chip is simplified. Therefore, the semiconductor chip can be efficiently manufactured, and the manufacturing cost can be kept low. Further, the core drill for dividing a semiconductor chip according to the present invention has a grinding cylinder whose end is opened with an opening size substantially equal to the outer diameter size of the semiconductor chip and the other end is connected to a driving device. In the peripheral part, an inner grinding surface inclined at an angle corresponding to the beveling surface of the semiconductor chip is provided by narrowing the inner diameter from the opening side toward the base side, and the outer diameter at the semiconductor chip dividing part in this grinding cylinder is set. Since it is constant,
When this semiconductor chip cutting core drill is used, since the semiconductor chip is beveled by the inner grinding surface of the grinding cylinder when the semiconductor chip is cut, it is possible to perform the cutting work and the beveling work with one core drill, Beveling can be performed with high accuracy and high efficiency. In addition, since the outer diameter of the portion where the semiconductor chip is divided in the grinding cylinder is constant, the force for expanding the hole diameter is not applied to the semiconductor wafer, so the semiconductor wafer is not cracked by this force.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a core drill according to the present invention, and FIGS. 2 (a) and 2 (b) are views for explaining the operation of the core drill according to the present invention, in which FIG. FIG. 3B is a sectional view showing a state in which the semiconductor chip is separated from the large-diameter substrate. Third
4 and 5 are cross-sectional views showing another embodiment of the core drill, FIG. 3 shows an example in which a grinding cylinder is formed thick, and FIG. 4 is a second grinding cylinder for beveling as a separate body. Here is an example provided. FIG. 5 is a cross-sectional view showing a conventional semiconductor chip used in a power thyristor, FIG. 6 is a perspective view showing a state before division of a large-diameter substrate on which a semiconductor chip portion is formed, and FIG. FIG. 6 is a perspective view showing a state where a large-diameter substrate is divided into individual semiconductor chips by a core drill. 1 ... Semiconductor chip, 4 ... Large-diameter substrate, 11 ... Core drill, 13 ... Body, 14,21,31 ... Grinding cylinder, 14c, 22,33 ...
… Inside ground surface.

Claims (2)

[Claims] 1. A method of manufacturing a power semiconductor device in which a semiconductor chip having a beveled outer peripheral portion is hollowed and separated from a semiconductor wafer by a rotating core drill, the inner diameter being reduced toward the base side. A method of manufacturing a power semiconductor device, wherein beveling is simultaneously performed at the time of cutting by a core drill having an inner ground surface and an outer peripheral surface having a constant outer diameter at a semiconductor chip cutting portion. 2. A grinding cylinder, one end of which is opened with an opening size substantially equal to the outer diameter of the semiconductor chip, and the other end of which is connected to a driving device. By narrowing the inner diameter toward the side, an inner grinding surface inclined at an angle corresponding to the beveling surface of the semiconductor chip is provided, and the outer diameter at the semiconductor chip dividing portion of this grinding cylinder is constant. Core drill for cutting semiconductor chips.