Semiconductor crystal wafer manufacturing apparatus and manufacturing method

Abstract

To provide semiconductor crystal wafer manufacturing apparatus and manufacturing method that can easily and reliably manufacture high-quality semiconductor crystal wafers.SOLUTION: A manufacturing method for a SiC wafer, which is a semiconductor crystal wafer, includes a groove processing step (STEP 100 / FIG. 1), a guide line forming step (STEP 110 / FIG. 1), a cutting step (STEP 120 / FIG. 1), and a grinding step (STEP 130 / FIG. 1).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for manufacturing a semiconductor crystal wafer, which cuts a wafer in a slice shape from a semiconductor crystal ingot ground into a cylindrical shape.

Background Art

[0002] Conventionally, as a method for manufacturing a SiC wafer, which is a semiconductor crystal wafer of this type, as shown in Patent Document 1 below, as a wafer shape forming step, an ingot forming step of processing a mass of grown single crystal SiC into a cylindrical ingot, a crystal orientation forming step of forming a notch in a part of the outer periphery so as to be a mark indicating the crystal orientation of the ingot, a slicing step of slicing the single crystal SiC ingot into a thin disk-shaped SiC wafer, a flattening step of flattening the SiC wafer using abrasive grains having a Mohs hardness less than the modified Mohs hardness, an engraving forming step of forming an engraving, and a chamfering step of chamfering the outer peripheral portion are included. Next, as a processed layer removing step, a processed layer removing step of removing the processed layer introduced into the SiC wafer in the previous step is included. Finally, as a mirror polishing step, a chemical mechanical polishing (CMP) step of performing polishing by combining the mechanical action of a polishing pad and the chemical action of a slurry is included. A method for manufacturing a SiC wafer is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, such a conventional method for manufacturing a SiC wafer has a problem that the manufacturing process is numerous and complicated, the apparatus configuration becomes complicated, and the manufacturing cost increases.

[0005] On the other hand, when the manufacturing process is simplified, it becomes difficult to stably obtain the quality required for the SiC wafer.

[0006] Therefore, an object of the present invention is to provide a manufacturing apparatus and a manufacturing method for a semiconductor crystal wafer capable of simply and surely manufacturing a high-quality semiconductor crystal wafer.

Means for Solving the Problems

[0007] The manufacturing apparatus for a semiconductor crystal wafer according to the first invention is a manufacturing apparatus for cutting a wafer in a slice shape from a semiconductor crystal ingot ground into a cylindrical shape, a guideline forming means for forming a cutting guideline by scanning a condensing point where a laser beam having a wavelength permeable to the semiconductor crystal ingot along a planned cutting surface; a cutting means for cutting the planned cutting surface of the semiconductor crystal ingot and is provided with The guideline forming means is characterized in that a scanning line corresponding to the cutting direction of the cutting means on the planned cutting surface is formed as the cutting guideline.

[0008] According to the manufacturing apparatus for a semiconductor crystal wafer of the first invention, since the cutting guideline formed on the planned cutting surface serves as a guide for cutting during cutting by the cutting means, the semiconductor crystal ingot can be accurately cut into a slice shape by the cutting means.

[0009] That is, during cutting, the cutting guideline becomes a region with less cutting resistance and serves as a guide for cutting for the cutting means.

[0010] Here, the cutting guideline is formed as a scanning line (for example, in addition to being the same as or perpendicular to the cutting direction, the density of the scanning lines corresponding to the cutting direction) corresponding to the cutting direction of the cutting means within the planned cutting plane corresponding to the cutting direction of the cutting means. Thus, when cutting by the cutting means, a region with less cutting resistance can be formed corresponding to the cutting direction.

[0011] As described above, according to the semiconductor crystal wafer manufacturing apparatus of the first invention, the semiconductor crystal ingot can be accurately cut into a slice shape, and a high-quality semiconductor crystal wafer can be manufactured simply and reliably.

[0012] The semiconductor crystal wafer manufacturing apparatus of the second invention is the same as that of the first invention, wherein the cutting means is a wire electrical discharge machining apparatus that advances while circulating a wire on the planned cutting plane and performs electrical discharge from the wire. According to the semiconductor crystal wafer manufacturing apparatus of the second invention, it is preferable that the cutting means is a wire electrical discharge machining apparatus, and the semiconductor crystal ingot can be accurately cut into a slice shape.

[0013] As described above, according to the semiconductor crystal wafer manufacturing apparatus of the second invention, the semiconductor crystal ingot can actually be accurately cut into a slice shape, and a high-quality semiconductor crystal wafer can be manufactured simply and reliably.

[0014] The semiconductor crystal wafer manufacturing apparatus of the third invention is the same as that of the first invention, wherein the cutting means is a cutter device that advances a cutting blade on the planned cutting plane. According to the semiconductor crystal wafer manufacturing apparatus of the third invention, it is preferable that the cutting means is a cutter device, and the semiconductor crystal ingot can be accurately cut into a slice shape.

[0015] Thus, according to the manufacturing apparatus for a semiconductor crystal wafer of the third invention, the semiconductor crystal ingot can actually be accurately cut into slices, and a high-quality semiconductor crystal wafer can be simply and surely manufactured.

[0016] The manufacturing apparatus for a semiconductor crystal wafer of the fourth invention is, in the first invention, The guideline forming means is characterized in that the cutting guideline is formed by a scanning line that coincides with the cutting direction of the cutting means.

[0017] According to the manufacturing apparatus for a semiconductor crystal wafer of the fourth invention, by forming the cutting guideline by a scanning line that coincides with the cutting direction of the cutting means, the cutting guideline, which is a region with less cutting resistance during actual cutting by the cutting means, is continuously formed in the cutting direction and serves as a guide for cutting.

[0018] Thus, according to the manufacturing apparatus for a semiconductor crystal wafer of the fourth invention, the semiconductor crystal ingot can actually be accurately cut into slices, and a high-quality semiconductor crystal wafer can be simply and surely manufactured.

[0019] The manufacturing apparatus for a semiconductor crystal wafer of the fifth invention is, in any one of the first to fourth inventions, The guideline forming means is characterized in that the laser beam is incident from the end face of the semiconductor crystal ingot.

[0020] According to the manufacturing apparatus for a semiconductor crystal wafer of the fifth invention, by making the laser beam for forming the cutting guideline incident from the end face of the semiconductor crystal ingot, the distance to the focal point is determined and the cutting guideline can be simply and surely formed by scanning along the traveling direction of the wire while maintaining that distance.

[0021] Thus, according to the manufacturing apparatus for a semiconductor crystal wafer of the fifth invention, a dicing guideline can be formed simply and reliably, and a semiconductor crystal ingot can be accurately diced into slices, enabling the simple and reliable production of high-quality semiconductor crystal wafers.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0023] As shown in FIG. 1, in this embodiment, the manufacturing method of the SiC wafer, which is a semiconductor crystal wafer, is a method for obtaining a SiC wafer cut out in a slice shape from a SiC ingot ground into a cylindrical shape, and includes a groove processing step (STEP100 / FIG. 1), a guideline formation step (STEP110 / FIG. 1), a dicing step (STEP120 / FIG. 1), and a grinding step (STEP130 / FIG. 1).

[0024] With reference to FIGS. 2 to 5, the details of each step and the manufacturing apparatus for the SiC wafer of this embodiment will be described.

[0025] First, in the groove processing step (STEP100 / Figure 1), a plurality of concave grooves 11 that encircle the entire side surface are formed on the SiC ingot 10 by a common groove processing drum grindstone 20.

[0026] The groove processing drum grindstone 20 is a drum grindstone for forming a plurality of concave grooves 11 that encircle the entire side surface of the SiC ingot 10, and a plurality of convex portions 21 corresponding to the plurality of concave grooves 11 are formed on the side surface.

[0027] Specifically, in the groove processing step (STEP100 / Figure 1), the concave grooves 11 are formed by pressing the SiC ingot 10 while rotating the groove processing drum grindstone 20, on whose side surface a plurality of convex portions 21 corresponding to the plurality of concave grooves 11 are formed, on rotating shafts parallel to each other.

[0028] At this time, the SiC ingot 10 is rotatably supported in a state where both of its end faces are protected via a pair of protective plates 15, 15.

[0029] The protective plate 15 is, for example, a synthetic resin such as polyvinyl chloride, and is joined to the SiC ingot 10 via an adhesive or the like as necessary.

[0030] With such a pair of protective plates 15, 15, both end portions of the SiC ingot 10 can be protected, and chipping and cracking of both end portions can be prevented. Therefore, a plurality of concave grooves 11 can be formed up to the vicinity of both end faces, and thus, more SiC wafers 100 described later can be obtained by cutting.

[0031] Also, when clamping and fixing the SiC ingot 10 to the rotating shaft, the protective plates 15, 15 can be processed (for example, drilled) and fixed as necessary. In addition, in this case as well, since the SiC ingot 10 itself is not processed, the SiC ingot 10 is not damaged.

[0032] Next, as shown in Fig. 3(a), prior to cutting by the wire 40, a cutting guideline is formed on the planned cutting surface by a guideline forming step (STEP110 / Fig. 1).

[0033] The planned cutting surface is a surface including each concave groove 11 formed by the groove processing step (STEP100 / Fig. 1) (a circular surface shown by a virtual line in the figure, which is smaller than the outer diameter of the ingot by the groove width). By positioning a condensing point where a laser beam having a wavelength that is transmissive to the SiC ingot 10 is condensed on such a planned cutting surface, a modified region of the SiC crystal is partially formed in the SiC ingot 10. Then, a desired cutting guideline is formed by a scanning line obtained by scanning the condensing point on the planned cutting surface.

[0034] As the guideline means for forming such a cutting guideline, a laser oscillator that oscillates the above-described laser beam and a condenser (lens) that condenses the laser beam inside the SiC ingot 10 are used.

[0035] Specifically, as shown in a cross-sectional view of the planned cutting surface in Fig. 3(b), a plurality of cutting guidelines are formed by scanning a plurality of times in the traveling direction of the wire 40 indicated by the arrow in the figure. The intervals between these cutting guidelines may be equal, but may be made sparse or dense such that the intervals become smaller toward the center and larger toward both the left and right sides.

[0036] By providing such sparseness or denseness, in the central part where the cutting amount is large when the wire 40 travels, the cutting speed decreases (conversely, the cutting speed increases on both sides), and where the wire 40 becomes bow-shaped, by providing a region with less cutting resistance stepwise from both sides to the central part, as shown in Fig. 3(c), it is possible to prevent the wire 40 from becoming bow-shaped and hold the wire in a straight line.

[0037] Note that the wire device used in the cutting process (STEP120 / Figure 1) by such a wire 40 (although various devices can be adopted) advances while circulating a plurality of wires 40 passed between wire bobbins, and discharges to the SiC ingot 10 by applying a high voltage (high-frequency high voltage) to the wire, thereby cutting the SiC ingot 10 into slices.

[0038] The wire 40 disposed in the concave groove 11, when advancing while circulating and discharging during cutting, in addition to the concave groove 11 (the outer diameter of the SiC ingot 10 being small), the cutting planned surface becomes a region with less cutting resistance due to the cutting guideline, and the wire 40 can cut while sliding on the cutting planned surface.

[0039] Thereby, the SiC ingot 10 can be accurately cut into slices at one time by a plurality of wires 40 disposed in a plurality of concave grooves 11. That is, high-speed cutting processing by the wire 40 can be realized, and surface flatness of the cutting surface and low-damage processing are possible. In addition, slicing at a specified thickness is possible even for a SiC ingot 10 with poor crystallinity in the entire surface or a specific region, and there is no influence of the crystal orientation.

[0040] Also, since the cutting resistance is small, the diameter of the wire 40 itself can be made small, and as a result, the wire replacement can be minimized and the yield can be improved.

[0041] Next, as shown in Figure 4, in the grinding process (STEP130 / Figure 1), in the first surface processing step (STEP130(1)), using one surface 110 of either side of the cutting surface as a support surface, mechanical polishing (high-precision grinding) is performed on the remaining other surface 120.

[0042] Specifically, in the first surface processing step (STEP130(1)), grinding is performed by a mechanical polishing device 50 (ultra-high synthesis high-precision grinding device) that performs mechanical polishing.

[0043] The mechanical polishing device 50 includes a spindle 51 and a diamond grinding wheel 53 on a platen 52 which is a surface plate.

[0044] First, with one surface 110 as the upper surface, it is adsorbed and supported by a vacuum porous chuck 54 which is the adsorption plate of the spindle 51, and with the other surface 120 as the lower surface, the other surface 120 is ground by the diamond grinding wheel 53.

[0045] At this time, the spindle 51 and the diamond grinding wheel 53 are rotationally driven by a driving device (not shown), and the spindle 51 is pressed against the diamond grinding wheel 53 by a compressor or the like (not shown), so that the other surface 120 is ground.

[0046] Note that after the grinding process, dressing of the diamond grinding wheel 53 may be performed by a dresser or the like.

[0047] Further, the mechanical polishing device 50 may have a functional water supply pipe so that a plurality of functional waters can be used during processing as needed.

[0048] Next, in the second surface processing step (STEP130(2)), with the other surface 120 which has been subjected to high-precision grinding in the first surface processing step as the upper surface, the same high-precision grinding as in the first surface processing step is performed on the one surface 110.

[0049] That is, with the other surface 120 as the upper surface, it is adsorbed by the vacuum porous chuck 54 which is the adsorption plate of the spindle 51, and with the one surface 110 as the lower surface, the one surface 110 is ground by the diamond grinding wheel 53.

[0050] Also in this case, dressing may be performed by pressing a dresser or the like against the diamond grinding wheel 53 as needed.

[0051] According to the mechanical polishing (high-precision grinding) treatment of the first surface processing step (STEP130(1)) and the second surface processing step (STEP130(2)), by using either one of the transferless cut surfaces with high flatness obtained by the cutting and polishing step as the support surface (adsorption surface) and sequentially performing mechanical polishing (high-precision grinding) on the remaining surface, so-called transfer can be prevented and high-quality SiC wafers can be obtained. At the same time, the conventional free abrasive machining, that is, complex manufacturing processes such as multiple laps from the first to the fourth time, can be greatly simplified.

[0052] More specifically, it is not necessary to change the grinding wheel and perform rough grinding or multiple finish grindings. For example, since it can be finished directly by one grinding process using a grinding wheel of #30000 or more, it is not only simple but also has the advantage that a large amount of the true semiconductor layer available from the SiC wafer 100 can be ensured.

[0053] In the high-precision grinding process of the first surface processing step (STEP130(1)) and the second surface processing step (STEP130(2)), the size of the SiC wafer 100 is currently up to 8 inches, and wafers of each diameter are set according to the area of the head, and (up to 12 inches is possible) the high-precision grinding process is performed.

[0054] The above is the detail of the manufacturing method of the SiC wafer of this embodiment. As described in detail above, according to the manufacturing method and apparatus of the SiC wafer of this embodiment, by actively forming regions with less cutting resistance by the concave grooves 11 and the cutting guide lines, these can serve as cutting guides, and the SiC ingot 10 can be accurately cut into slices at one time with a plurality of wires 40.

[0055] Next, with reference to FIG. 5, a modified example of the cutting guide line will be described. Specifically, as shown in Fig. 5(a), the cutting guide line is not limited to the end face of the SiC ingot 10, and by making the laser beam incident from the side face, as shown in the cross-sectional view of the planned cutting surface in Fig. 5(b), a plurality of cutting guide lines may be formed concentrically on the planned cutting surface. For example, by rotating the SiC ingot 10 around its axis, concentric cutting guide lines can be easily formed.

[0056] And also in this case, the wire 40 disposed in the concave groove 11, when advancing while orbiting during cutting, in addition to the concave groove 11 in the uncut region, the cutting guide line becomes a region with less cutting resistance and serves as a guide for cutting. Also in this case, since the plurality of concentric cutting guide lines are denser toward the central part of the SiC ingot 10, as shown in Fig. 5(c), it is possible to prevent the wire 40 from becoming bow-shaped and hold the wire linearly.

[0057] Note that in the above embodiment, the cutting guide line is not limited to the case where it is aligned with the advancing direction of the wire 40 or the case where it is formed concentrically. The cutting guide line may be any as long as it takes into account the advancing direction of the wire 40. For example, starting from the cutting end point of the wire 40, cutting guide lines may be formed in a scanning direction that is radial in the advancing and retreating direction of the wire (in this case, the retreating direction).

[0058] Also in this case, since the central part of the SiC ingot has denser cutting guide lines compared to the left and right sides, regions with less cutting resistance are provided step by step from both sides to the central part, and it is possible to prevent the wire 40 from becoming bow-shaped and hold the wire linearly.

[0059] Of course, instead of or in addition to the radial shape starting from the cutting end point of the wire 40, cutting guide lines may be formed in a scanning direction that is radial in the advancing and retreating direction of the wire (in this case, the advancing direction) starting from the cutting start point.

[0060] In this way, by providing the radial cutting guide lines starting from the cutting start point and the cutting end point, the cutting at the cutting start point and the cutting end point can be performed with almost no cutting resistance, and the cutting finish at these cutting start points and cutting end points can be significantly improved.

[0061] Furthermore, the guideline forming step (STEP110 / Figure 1) of the present embodiment may be applied to the thin film processing of the backside formation for the purpose of wafer regeneration.

[0062] Also, in the manufacturing method of the SiC wafer of the present embodiment, after the above-described series of processes, a chemical mechanical polishing (CMP) process or a wafer cleaning process may be performed as necessary.

[0063] Furthermore, in the present embodiment, the case of manufacturing a SiC wafer from a SiC ingot has been described as a manufacturing method of a semiconductor crystal wafer. However, the semiconductor crystal is not limited to SiC, and may be gallium arsenide, indium phosphide, silicon, or other compound semiconductors.

[0064] Also, in the present embodiment, in the groove processing step (STEP100 / Figure 1), the case where the SiC ingot 10 is rotatably supported while its both end faces are protected via a pair of protective plates 15, 15 has been described. However, it is not limited thereto. For example, the pair of protective plates 15, 15 may be omitted and the SiC ingot 10 may be directly fixed to the rotating shaft.

[0065] Furthermore, in steps other than the groove processing step (STEP100 / Figure 1), for example, in the cutting step (STEP120 / Figure 1), the processing may be performed while protecting both end faces of the SiC ingot 10 by a pair of protective plates 15, 15.

[0066] In addition, in this embodiment, in the groove machining step (STEP100 / Figure 1), the case where a plurality of concave grooves 11 that go around the entire side surface are formed on such a SiC ingot 10 by a common groove machining drum grindstone 20 has been described. However, the groove machining step of STEP100 may be omitted, and the case where the concave grooves 11 are not formed may also be possible.

[0067] Also, in this embodiment, as the cutting means, an electric discharge machining apparatus which is an electric discharge type wire saw apparatus has been described as an example. However, the cutting means is not limited to this, and in addition to a wire saw apparatus without an electric discharge function, a cutter apparatus (including the case having an electric discharge function) may also be used. In this case, the shape of the cutting blade may be, in addition to a disk-shaped ring blade, a saw blade of a hacksaw or the like.

[0068] Furthermore, in this embodiment, as the cutting guide line formed in the guideline forming step (STEP110 / Figure 1), mainly, a scanning line that coincides with the cutting direction has been described as an example for corresponding to the cutting direction. However, the scanning line corresponding to the cutting direction is not limited to this, and in addition to a scanning line orthogonal to the cutting direction, density differences may be provided in the scanning line corresponding to the cutting direction.

[0069] For example, as shown in FIG. 6, a cutting guide line of a radial scanning line starting from the cutting end point of the cutting means (the wire of the wire saw apparatus) and going in the cutting direction (the traveling direction of the wire) may be formed. By making the scanning line radial in this way, when cutting, for example, regions with less cutting resistance can be provided step by step from both sides to the central part, and it is possible to prevent the central part of the wire from being sent in an arc shape in the cutting region. At the same time, since the final cutting part is the radiation point (it can be cut in a state without cutting resistance), the finish of the final cutting part is excellent.

[0070] Note that in addition to or instead of starting from the cutting end point of the cutting means (the wire of the wire saw apparatus), such a radial scanning line may start from the cutting start point. In this case, since the cutting start point part is the radiation point (it can be cut in a state without cutting resistance), the finish of the cutting start point part is excellent.

Explanation of Symbols

[0071] 1…SiC crystal (semiconductor crystal), 4…wire saw device (electrical discharge machining device), 10…SiC ingot (semiconductor crystal ingot), 11…concave groove, 15, 15…pair of protective plates, 20…groove machining drum grindstone, 21…protrusion, 40…wire, 50…mechanical polishing device (ultra-high synthesis high-precision grinding device), 51…spindle, 52…platen, 53…diamond grindstone, 54…vacuum porous chuck (adsorption plate), 100…SiC wafer (semiconductor crystal wafer), 110…one side, 120…the other side.

Claims

1. A manufacturing apparatus for a semiconductor crystal wafer that cuts a wafer in a slice shape from a semiconductor crystal ingot ground into a cylindrical shape, comprising: a guideline forming means for forming a cutting guideline by scanning a condensing point of a laser beam having a wavelength that is transmissive to the semiconductor crystal ingot along a planned cutting surface; a cutting means for cutting the planned cutting surface of the semiconductor crystal ingot; and the guideline forming means forms a scanning line corresponding to the cutting direction of the cutting means on the planned cutting surface as the cutting guideline. A manufacturing apparatus for a semiconductor crystal wafer characterized by this.

2. In the manufacturing apparatus for a semiconductor crystal wafer according to Claim 1, the cutting means is a wire electrical discharge machining apparatus that advances while circulating a wire on the planned cutting surface and performs electrical discharge from the wire. A manufacturing apparatus for a semiconductor crystal wafer characterized by this.

3. In the manufacturing apparatus for a semiconductor crystal wafer according to Claim 1, the cutting means is a cutter apparatus characterized by advancing a cutting blade on the planned cutting surface. A manufacturing apparatus for a semiconductor crystal wafer characterized by this.

4. In the manufacturing apparatus for a semiconductor crystal wafer according to Claim 1, the guideline forming means forms the cutting guideline with a scanning line that coincides with the cutting direction of the cutting means. A manufacturing apparatus for a semiconductor crystal wafer characterized by this.

5. In the manufacturing apparatus for a semiconductor crystal wafer according to any one of Claims 1 to 4, the guideline forming means is characterized by making the laser beam incident from an end face of the semiconductor crystal ingot. A manufacturing apparatus for a semiconductor crystal wafer characterized by this.

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