JP2023091696A - Production method and production device for semiconductor crystal wafer - Google Patents

Abstract

To provide a production method and a production device for a semiconductor crystal wafer that make it possible to easily and reliably produce a semiconductor crystal wafer of high quality.SOLUTION: A method for producing a SiC wafer which is a semiconductor crystal wafer is for obtaining a SiC wafer by performing high-precision grinding of a surface of a wafer cut as a slice from a SiC ingot ground into a cylindrical shape. The method comprises a groove processing step (STEP 100 in figure 1), a cutting step (STEP 110 in figure 1), an undulation removal step (STEP 120 in figure 1), a first surface processing step (STEP 130 in figure 1), and a second surface processing step (STEP 140 in figure 1).SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor crystal wafer in which the surface of a wafer sliced from a cylindrically ground semiconductor crystal ingot is subjected to high-precision grinding.

Conventionally, as a method for manufacturing a SiC wafer, which is a semiconductor crystal wafer of this type, as a wafer shape forming step, a mass of crystal-grown single-crystal SiC is processed into a columnar ingot, as shown in Patent Document 1 below. An ingot forming process, a crystal orientation forming process of forming a notch in a part of the outer circumference so as to serve as a mark indicating the crystal orientation of the ingot, and slicing the single crystal SiC ingot and processing it into a thin disc-shaped SiC wafer. a slicing step, a flattening step of flattening the SiC wafer using abrasive grains less than the modified Mohs hardness, a stamp forming step of forming a stamp, and a chamfering step of chamfering the outer peripheral portion, and then processing The process-affected layer removal process includes a process-affected layer removal process for removing the process-affected layer introduced into the SiC wafer in the preceding process. Finally, as a mirror polishing process, the mechanical action of the polishing pad and the chemical reaction of the slurry A SiC wafer manufacturing method is known that includes a chemical mechanical polishing (CMP) process in which polishing is performed using a combination of various effects.

Japanese Patent Application Laid-Open No. 2020-15646

However, such a conventional SiC wafer manufacturing method involves a large number of manufacturing steps and is complicated, resulting in a complicated apparatus configuration and an increased manufacturing cost.

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

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a semiconductor crystal wafer manufacturing method and manufacturing apparatus that can easily and reliably manufacture high-quality semiconductor crystal wafers.

A method for manufacturing a semiconductor crystal wafer according to a first aspect of the invention is a method for manufacturing a semiconductor crystal wafer by cutting a wafer into slices from a semiconductor crystal ingot ground into a cylindrical shape,
a cutting step of cutting the semiconductor crystal ingot into slices with a plurality of wires to obtain semiconductor crystal wafers;
a waviness removing step of removing waviness on one surface of the semiconductor wafer cut into slices by the cutting step;
In the waviness removing step, two of the plurality of semiconductor crystal wafers cut in the cutting step are taken as a pair, and a flat grindstone having both surfaces to be ground is sandwiched from both sides, and the pair of semiconductor crystal wafers and the flat grindstone are sandwiched from both sides. By sliding either one or both of and, undulations on one surface of each of the pair of semiconductor wafers are removed.

According to the method for manufacturing a semiconductor crystal wafer of the first invention, first, a semiconductor crystal ingot is cut into slices with high precision by a wire.

Then, a pair of a plurality of semiconductor wafers cut into slices is set as one set, and either one or both of the pair of semiconductor crystal wafers and the flat grindstone are placed in a state in which a flat grindstone having grinding surfaces on both sides is sandwiched from both sides. Sliding (for example, one or both of rocking and rotating) can remove waviness on each side of the pair of semiconductor wafers.

As a result, the undulations and streaks of the cut surface can be polished and removed to make it a reference surface, and the loose grinding stone processing that is generally performed in the flattening process, that is, multiple times of the first to fourth times Complicated manufacturing processes such as wrapping can be greatly simplified.

Thus, according to the semiconductor crystal wafer manufacturing method of the first invention, it is possible to easily and reliably manufacture a high-quality semiconductor crystal wafer.

A semiconductor crystal wafer manufacturing apparatus according to a second aspect of the present invention is a semiconductor crystal wafer manufacturing apparatus for cutting wafers into slices from a semiconductor crystal ingot ground into a cylindrical shape,
a wire saw section for cutting the semiconductor crystal ingot by advancing a plurality of wires while rotating them;
a waviness removing unit for removing waviness on one surface of the semiconductor wafer cut into slices by the wire saw unit;
The undulation removing unit includes:
A flat whetstone with grinding surfaces on both sides,
any one of a wafer supporting portion that supports a pair of two semiconductor crystal wafers cut by the wire saw while sandwiching the flat grindstone from both sides; and the flat grindstone and the pair of semiconductor crystal wafers. a sliding mechanism for sliding one or both in the plate surface direction;
in a state in which the pair of semiconductor wafers sandwich the flat grindstone from both sides by the wafer supporting portion, and the slide mechanism slides either one or both of the pair of semiconductor crystal wafers and the flat grindstone. undulations on the respective surfaces of the pair of semiconductor wafers are removed.

According to the semiconductor crystal wafer manufacturing apparatus of the second invention, the apparatus realizes the semiconductor crystal wafer manufacturing method of the first invention.

First, the wire saw section cuts the semiconductor crystal ingot into slices with high accuracy.

Next, two of the plurality of semiconductor wafers cut by the wafer supporting portion of the waviness removing portion are grouped into one set, and a flat grindstone having grinding surfaces on both sides can be sandwiched from both sides. By sliding one or both of the pair of semiconductor crystal wafers and the flat grindstone (for example, one or both of rocking and rotating) to remove undulations on each side of the pair of semiconductor wafers. can be done.

As a result, the undulations and streaks of the cut surface can be polished and removed to make it a reference surface, and the loose grinding stone processing that is generally performed in the flattening process, that is, multiple times of the first to fourth times Complicated manufacturing processes such as wrapping can be greatly simplified.

Thus, according to the semiconductor crystal wafer manufacturing apparatus of the second invention, it is possible to actually manufacture high-quality semiconductor crystal wafers easily and reliably.

4 is a flow chart showing the overall steps of a method for manufacturing a SiC wafer (semiconductor crystal wafer) according to the present embodiment; FIG. 2 is an explanatory diagram showing the contents of a groove processing step and a cutting step in the method of manufacturing the SiC wafer of FIG. 1; FIG. 2 is an explanatory view showing the content of a waviness removal step in the method of manufacturing the SiC wafer of FIG. 1; FIG. 2 is an explanatory diagram showing the contents of a first surface processing step and a second surface processing step in the method of manufacturing the SiC wafer of FIG. 1; FIG. 2 is an explanatory view showing a modification of the waviness removing step in the method of manufacturing the SiC wafer of FIG. 1;

As shown in FIG. 1, in the present embodiment, a SiC wafer, which is a semiconductor crystal wafer, is produced by slicing a SiC ingot ground into a cylindrical shape and removing undulation from one surface of the wafer. , comprising a grooving step (STEP 110/FIG. 1), a cutting step (STEP 120/FIG. 1), a waviness removing step (STEP 130/FIG. 1), and a first surface machining step (STEP 140/FIG. 1). and a second face machining step (STEP 150/FIG. 1).

Details of each step and devices used in each step will be described with reference to FIGS.

First, in the grooving step of STEP 100 shown in FIG. 2, a cylindrical SiC ingot 10 obtained by determining the crystal orientation and applying cylindrical grinding to a pre-crystallized SiC crystal in the ingot processing step is prepared. .

Then, in the grooving step of STEP 100 , a plurality of grooves 11 are formed around the entire side surface of the SiC ingot 10 .

Specifically, in the grooving step of STEP 100, grooving drum grindstones 20 having convex portions 21 corresponding to the grooves 11 formed on the side surfaces thereof are pressed against the SiC ingot 10 while being rotated on rotating shafts parallel to each other. to form the recessed groove 11 .

In addition, it is desirable to subject the SiC ingot 10 (especially the grooves 11) obtained by the grooving process to a non-damaging mirror-finishing process using a chemical treatment method.

Next, in a cutting step of STEP 110 , SiC ingot 10 is cut into slices by a plurality of wires 31 arranged in a plurality of grooves 11 formed in the groove processing step to obtain SiC wafers 100 .

Specifically, in the cutting step, a plurality of wires 31 of a wire saw device 3 (corresponding to the wire saw portion of the present invention), which is a cutting device, are aligned with the plurality of grooves 11 formed in the groove processing step, The SiC ingot 10 is cut into slices by advancing the wire while winding it.

At this time, it is preferable to form a plurality of bobbin grooves corresponding to the plurality of convex grooves 21 on the entire side surface of the wire saw bobbin 31 around which the plurality of wires 32 of the wire saw device 3 are wound.

As a result, the wire 32 circulates through the wire bobbin 31 in which bobbin grooves having the same shape as the plurality of grooves 11 are formed. The SiC ingot 10 can be accurately cut into slices in one operation.

In this way, in the grooving step, the groove 11 is previously formed around the entire side surface of the SiC ingot, and the SiC ingot 10 can be cut into slices with high accuracy by the wire 31 using the groove 11 as a guide. , there is no need to perform the chamfering process again.

Next, as shown in FIG. 3, in the waviness removal step of STEP 120, waviness on one surface of the SiC wafer 100 obtained by the cutting step is removed.

Specifically, in the waviness removing step, a waviness removing device 40 (corresponding to the waviness removing section of the present invention) is used.

The waviness removing device 40 includes a flat plate grindstone 41 (for example, a diamond flat plate grindstone) having grinding surfaces on both sides, and a swing mechanism 42 (corresponding to the sliding mechanism of the present invention, for example, an actuator) for swinging the flat plate grindstone 41 in the plate surface direction. device, etc.), and a wafer supporting portion 43 that supports two SiC wafers 100 as a pair so as to press against the flat grindstone 41 in a state where the flat grindstone 41 is sandwiched from both sides.

Here, the SiC wafer 100 is housed in the template of the wafer support portion 43 (resin template into which the SiC wafer 100 is fitted) with the polishing surface facing the flat grindstone 41 . pressed.

At this time, in the template of the wafer support portion 43, for example, a sponge-like back pad containing water is provided, and the SiC wafer 100 is ground by a flat grindstone in the direction indicated by the arrow in the drawing with an appropriate force. 41 is pressed.

Further, at this time, as indicated by arrows in the figure, the flat grindstone 41 is oscillated in the plate surface direction by the oscillating mechanism 42, so that the polishing surfaces 110 of the pair of SiC wafers 100 are simultaneously polished.

As a result, undulations and streaks at the time of cutting are polished off and removed from the ground surface 110, and the ground surface 110 can be used as a reference surface in a surface processing step, which will be described later.

In this embodiment, two rocking mechanisms 42 are shown installed in the horizontal direction, but one is a rocking device such as an actuator, and the other is an urging means such as a spring. It may be used as a swing assisting means. Further, the swing mechanism 42 may be installed in the vertical direction instead of or in addition to the horizontal direction (the swing assisting means may also be installed).

Next, as shown in FIG. 4, in the first surface processing step of STEP 130, the polished surface 110 of the SiC wafer 100 is used as a support surface, and the remaining other surface 120 is subjected to mechanical polishing (high-precision grinding). This is because the polished surface 110 of the SiC wafer 100 polished by the waviness removing step of STEP 120 has high smoothness and can be used as a support surface (reference surface).

Specifically, in the first surface processing step, grinding is performed by a mechanical polishing device 50 (ultra-high synthetic high-precision grinding processing device) that performs mechanical polishing.

A mechanical polisher 50 includes a spindle 51 and a diamond grindstone 53 on a platen 52 which is a surface plate.

First, with the polished surface 110 as the upper surface, the vacuum porous chuck 54, which is the suction plate of the spindle 51, is attracted and supported.

At this time, the spindle 51 and the diamond grindstone 53 are rotationally driven by a drive device (not shown), and the spindle 51 is pressed against the diamond grindstone 53 by a compressor (not shown) or the like, whereby the remaining other surface 120 is ground. .

After grinding, the diamond grindstone 53 may be dressed by a dresser or the like.

In addition, the mechanical polisher 50 may have functional water supply piping so that a plurality of functional waters can be used during processing, if necessary.

Next, in the second surface processing step of STEP 140, one surface 110 (polished surface) is subjected to the first surface processing step with the other surface 120 subjected to high-precision grinding in the first surface processing step as the upper surface. A similar high-precision grinding process is applied.

That is, with the other surface 120 as the upper surface, it is attracted to the vacuum porous chuck 54 that is the suction plate of the spindle 51 , and the one surface 110 is ground with the diamond grindstone 53 with the one surface 110 as the lower surface.

In this case, too, dressing may be performed by pressing a dresser or the like against the diamond grindstone 53 as necessary.

According to the mechanical polishing (high-precision grinding) processing in the first surface processing step of STEP 130 and the second surface processing step of STEP 140, the polished surface 110 having high flatness obtained by the waviness removal step is attached to the supporting surface (adsorption). surface), mechanical polishing (high-precision grinding) is sequentially applied to the remaining surfaces, so-called transfer can be prevented and a high-quality SiC wafer can be obtained. It is possible to greatly simplify the complicated manufacturing process, such as multiple times of primary to quaternary lapping.

More specifically, there is no need to perform rough grinding or finish grinding multiple times by changing the grindstone. In addition, there is an advantage that a large intrinsic semiconductor layer that can be used from the SiC wafer 100 can be secured.

In the high-precision grinding process of the first surface processing step of STEP 130 and the second surface processing step of STEP 140, the size of the SiC wafer 100 is currently up to 8 inches, and the diameter of each wafer varies depending on the area of the head. It is then set (possibly up to 12 inches) and subjected to the precision grinding process.

The details of the method for manufacturing the SiC wafer according to the present embodiment have been described above. As described above in detail, according to the SiC wafer manufacturing method of the present embodiment, a high-quality SiC wafer can be manufactured easily and reliably.

In the SiC wafer manufacturing method of the present embodiment, a chemical mechanical polishing (CMP) process and a wafer cleaning process may be performed after the series of processes described above, if necessary.

In addition, in the present embodiment, as a method for manufacturing a semiconductor crystal wafer, a case of manufacturing a SiC wafer from a SiC ingot has been described, but the semiconductor crystal is not limited to SiC, and the semiconductor crystal is not limited to SiC. Other compound semiconductors may be used.

In the SiC wafer manufacturing method of the present embodiment, the waviness removing device 40 used in the waviness removing step may be modified as shown in FIG. In addition, in FIG. 5, the same configurations are denoted by the same reference numerals, and the description thereof is omitted.

In FIG. 5, a flat grindstone 41 is connected to one end of a link mechanism 42' (corresponding to the sliding mechanism of the present invention), and is swingable or rockable in the direction of the plate surface by a rotation drive section (not shown) on the other end side. It may be configured to be dynamically rotatable.

Instead of the link mechanism 42', a crank mechanism may be employed to reciprocate the flat grindstone 41 in the direction of the plate surface, and the flat grindstone 41 may be simply rotated via a gear mechanism instead of the link mechanism 42'. You can let it run.

In FIG. 5, when two SiC wafers 100 are pressed against the flat grindstone 41 with the flat grindstone 41 sandwiched from both sides by the wafer support portion 43, rotation driving means such as a motor (not shown) is operated. The pair of SiC wafers 100 may be oscillatingly rotated by being connected to the rotary shaft via a universal joint 44 (corresponding to the sliding mechanism of the present invention) and pressed.

It should be noted that the universal joint 44 may be omitted and the wafer support portion 43 may be simply rotated. A swinging device such as an actuator for swinging may be provided at the end of the wafer supporting portion 43 to simply swing.

As described above, in the waviness removing step, one or both of the pair of SiC wafers 100 and the flat grindstone 41 are slid by various sliding mechanisms (for example, including one or both of rocking and rotating). The undulations may be removed by applying a non-limiting method.

In addition, in the present embodiment, the case where the cutting process is performed after the grooving process has been described, but the present invention is not limited to this. A pretreatment step may be performed.

DESCRIPTION OF SYMBOLS 1... SiC crystal (semiconductor crystal), 10... SiC ingot (semiconductor crystal ingot), 11... Groove, 20... Grooving drum grindstone, 21... Convex part, 30... Wire saw apparatus (wire saw part), 31... Wire Saw bobbin 32 wire 40 waviness removing device (waviness removing unit) 41 flat grindstone 42 rocking mechanism (sliding mechanism) 42′ link mechanism (sliding mechanism) 43 wafer supporting unit 44 -- Universal joint (sliding mechanism), 50 -- Mechanical polishing device (ultra-high synthetic high-precision grinding device), 51 -- Spindle, 52 -- Platen, 53 -- Diamond whetstone, 54 -- Vacuum porous chuck (adsorption plate), 100 ... SiC wafer (semiconductor crystal wafer), 110 ... polished surface (reference surface, one surface), 120 ... other surface.

Claims (2)

A method for manufacturing a semiconductor crystal wafer by cutting a wafer into slices from a semiconductor crystal ingot ground into a cylindrical shape, comprising:
a cutting step of cutting the semiconductor crystal ingot into slices with a plurality of wires to obtain semiconductor crystal wafers;
a waviness removing step of removing waviness on one surface of the semiconductor wafer cut into slices by the cutting step;
In the waviness removing step, two of the plurality of semiconductor crystal wafers cut in the cutting step are taken as a pair, and a flat grindstone having both surfaces to be ground is sandwiched from both sides, and the pair of semiconductor crystal wafers and the flat grindstone are sandwiched from both sides. A method of manufacturing a semiconductor crystal wafer, wherein undulations on each side of the pair of semiconductor wafers are removed by sliding one or both of and. A semiconductor crystal wafer manufacturing apparatus for cutting wafers into slices from a semiconductor crystal ingot ground into a cylindrical shape,
a wire saw section for cutting the semiconductor crystal ingot by advancing a plurality of wires while rotating them;
a waviness removing unit for removing waviness on one surface of the semiconductor wafer cut into slices by the wire saw unit;
The undulation removing unit includes:
A flat whetstone with grinding surfaces on both sides,
any one of a wafer supporting portion that supports a pair of two semiconductor crystal wafers cut by the wire saw while sandwiching the flat grindstone from both sides; and the flat grindstone and the pair of semiconductor crystal wafers. a sliding mechanism for sliding one or both in the plate surface direction;
in a state in which the pair of semiconductor wafers sandwich the flat grindstone from both sides by the wafer supporting portion, and the slide mechanism slides either one or both of the pair of semiconductor crystal wafers and the flat grindstone. 1. An apparatus for manufacturing semiconductor crystal wafers, characterized in that undulations on each side of the pair of semiconductor wafers are removed by aligning them.

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