JP5315573B2 - Processing apparatus and processing method - Google Patents

Description

  The present invention relates to a processing apparatus and a processing method suitable for cutting or forming grooves of difficult-to-work products such as SiC (silicon carbide) and GaN (gallium nitride).

  In recent years, SiC single crystals that are wide band gap semiconductors have attracted attention as next-generation power semiconductor device materials, and research into practical application of SiC devices exceeding the performance of Si (silicon) has been conducted. This SiC is sliced from a crystal ingot to form a wafer, and then mechanical polishing and chemical polishing are performed to produce the surface. However, since SiC is chemically stable and has hardness next to diamond, it is very difficult to process, and it is difficult to apply conventional silicon processing techniques as they are.

Conventionally, as a cutting technique for SiC, there is a method using a metal bond grindstone, a diamond blade saw or the like as disclosed in Patent Documents 1 and 2, for example.
JP 2000-79561 A JP 2002-254283 A

  However, in the cutting process using a diamond blade saw or the like as in the prior art, the crystal lattice is damaged, and it is difficult to obtain a smooth cut surface. Therefore, a method that can suppress the introduction of crystal defects and cut SiC with high precision is desired. This is not limited to ingot slicing, and the same applies to the cutting process when element separation is performed after forming a wafer. Furthermore, when forming fine grooves on the wafer surface, it has been difficult to sufficiently smooth the inner surface of the grooves. Such a problem is not limited to SiC but also applies to materials such as GaN and sapphire.

  The present invention has been made in view of such problems, and its purpose is to smoothly cut or form a smooth groove while suppressing the introduction of damage to difficult-to-work materials such as SiC and GaN. It is an object of the present invention to provide a processing apparatus and a processing method that can be used.

A processing apparatus according to the present invention includes a holding table for holding a workpiece, a blade-shaped processing member that is formed of a transition metal and is in contact with or in close proximity to the surface of the workpiece, and the workpiece of the processing member And an oxidant supply means for supplying an oxidant to a portion opposite to the substrate, and a drive means for holding the processing member and reciprocally moving the processing member relative to the workpiece along the longitudinal direction of the processing member. provided, by cutting the workpiece, or all SANYO forming a groove in the workpiece, the oxidant is H ₂ O ₂ (hydrogen peroxide), the workpiece is, Fe (iron), Ni (nickel ), Co (cobalt), Cu (copper), Cr (chromium) and Ti (titanium), and the workpiece is crystalline SiC, sintered SiC, GaN, AlN, sapphire Out of ruby and diamond Consisting of Zureka one.

In addition, the processing method of the present invention specifically includes a blade-shaped processing member formed of a transition metal in contact with or close to the surface of the workpiece, and a portion of the processing member facing the workpiece. The workpiece is smoothly cut or the workpiece is smoothed by reciprocating the workpiece along the longitudinal direction of the workpiece with respect to the workpiece. This is a method of forming a groove , the oxidizing agent is H ₂ O ₂ (hydrogen peroxide), and the workpiece is Fe (iron), Ni (nickel), Co (cobalt), Cu (copper), Cr (chromium) ) And Ti (titanium), and the workpiece is made of any one of crystalline SiC, sintered SiC, GaN, AlN, sapphire, ruby, and diamond.

In the processing apparatus or processing method of the present invention, the above processing is preferably performed in a solution containing an oxidizing agent, H ₂ O ₂ (hydrogen peroxide) as the oxidizing agent, and Fe (iron) as the processing member. , Ni (nickel), Co (cobalt), Cu (copper), Cr (chromium), and Ti (titanium).

Further, as the workpiece, crystalline SiC, sintered SiC, GaN, sapphire, ruby, diamond, or the like can be used. In particular, it is preferable that the oxidizing agent is H ₂ O ₂ , the processed member is formed of Fe, and the workpiece is a SiC substrate or a GaN substrate.

  Moreover, you may make it perform the said process, supplying an electric current to a process member.

  In the processing apparatus or processing method of the present invention, an active species having a strong oxidizing power is generated by using an oxidant as a catalyst for the transition metal constituting the processed member, and the workpiece is brought into contact with or in close proximity to the active species. Surface atoms on the surface of the workpiece are oxidized. The oxidized surface atoms are removed or eluted as the workpiece is reciprocated, whereby the workpiece is cut or grooves are formed in the workpiece.

  According to the processing apparatus or the processing method of the present invention, the processing member made of a transition metal is brought into contact with or close to the surface of the workpiece and reciprocated, and the processing member is moved to the region including the portion facing the workpiece. Since the oxidizing agent is supplied, cutting or groove formation can be performed by a chemical method without using abrasive grains or abrasives. Therefore, the introduction of damage to the processed surface can be suppressed. In addition, the workpiece is processed only while the workpiece is in contact with or in close proximity, and the processing area is limited to only the area in which the workpiece is in contact or in close proximity, making it easy to control the processing with high accuracy. A smooth cut surface can be formed, or a groove having a smooth inner surface can be formed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the overall configuration of a processing apparatus according to an embodiment of the present invention. The processing apparatus 1 includes a container 11 containing an oxidant solution 11a. A holding table 12 is provided at the bottom of the container 11, and the workpiece 13 is held on the holding table 12. A processing head 14 is disposed above the holding table 12, and a blade (processing member) 15 formed of a transition metal is held at the tip of the processing head 14. The machining head 14 can be reciprocated in the direction (vertical direction) indicated by an arrow in the figure in a state where the blade 15 is in contact with or in close proximity to the workpiece 13 by a drive mechanism (not shown). The object 13 can be cut at an arbitrary position, or a groove can be formed at an arbitrary position of the workpiece 13.

The container 11 is formed of a resin material having excellent chemical resistance such as a fluororesin or a vinyl chloride resin. The oxidizing agent accommodated in the container 11 generates active species for cutting the workpiece 13 by a redox reaction using a transition metal constituting the blade 15 as a catalyst. As the oxidizing agent, for example, hydrogen peroxide (H ₂ O ₂ ) is used, but it can be changed to various materials depending on a combination of a workpiece, a catalyst, processing conditions, and the like.

  The blade 15 made of a transition metal serves as a catalyst for redox decomposition of the oxidant as described above, and is made of, for example, Fe (iron). In addition, Ni (nickel), Co (cobalt), Cu (copper), Cr (chromium), Ti (titanium), or the like can be used.

  The workpiece 13 is, for example, a crystalline or sintered SiC substrate, but may be made of GaN, AlN, diamond, sapphire, ruby, or the like. Moreover, the shape is not limited to a plate shape, and may be any shape such as an ingot shape.

  Next, the operation of the processing apparatus 1 will be described with reference to FIG. In addition, about the processing method of this invention, since it is embodied in the effect | action of this processing apparatus 1, the description is abbreviate | omitted.

First, as shown in FIG. 2A, the workpiece 13 is placed in a container 11 containing an oxidant solution, and a processing head 14 having a blade 15 is immersed therein. As a result, the catalytic metal constituting the blade 15 reacts with the oxidizing agent, and active species 16 are generated on the surface of the blade 15. Specifically, as shown in the following chemical structural formulas 1 and 2, the oxidant (H ₂ O ₂ ) causes a Fenton reaction using the transition metal (Fe 2+) constituting the blade 15 as a catalyst, and the active species As a result, OH radical (OH .; hydroxyl radical) is generated. That is, it is decomposition of H ₂ O ₂ by the Harber-Waiss mechanism, and OH radicals are generated by one-electron reduction with low-valent transition metals (Fe 2+, Ti 3+, Cr 2+, Cu + etc.). The OH radical has a short lifetime but has a very strong oxidizing power.

Next, as shown in FIG. 2B, the blade 15 is brought into contact with or in close proximity to the workpiece 13 and reciprocated. At this time, surface atoms (SiC) 17 on the surface of the workpiece 13 in a region close to the blade 15 are oxidized. Specifically, as shown in the following chemical formula 3, the active species 16 (OH.) And the dissolved oxygen (O ₂ ) in the oxidizing agent oxidize the surface atoms 17 of the workpiece 13, and the oxide 18 (SiO 2 ₂ ) and this oxide 18 is removed or eluted. Then, a new work surface appears and processing proceeds. That is, when the workpiece 13 approaches the blade 15, the workpiece 13 is preferentially processed in an area close to the blade 15, and is cut smoothly as shown in FIG. Alternatively, the groove 13a is formed as shown in FIG. At this time, the machining speed can be increased by increasing the reciprocating speed of the blade 15 . In the oxidant solution, in addition to the active species and oxides, unreacted oxidant molecules 19 and oxidant molecules are dissociated, and residual molecules 20 in which active species 16 are generated remain.

  When the cutting or groove formation is completed, the blade 15 is separated from the workpiece 13 as shown in FIG. At this time, the oxide 18 is removed from the surface of the workpiece 13 as described above. In addition, the unreacted active species 16 binds to the remaining molecule 20 and is inactivated. Therefore, the workpiece 13 is oxidized only while the blade 15 is in close proximity, and the workpiece 13 is not oxidized when the blade 15 is separated from the workpiece 13. That is, since the workpiece 13 is processed only when it is in contact with or close to the blade 15, it is possible to easily control cutting or groove formation.

  As described above, in this embodiment, since chemical processing is performed using the active species 16 generated by the oxidizing agent and the transition metal (blade 15), SiC or the like can be used without using abrasive grains or abrasives. This difficult-to-work product can be cut with high accuracy or a groove can be formed.

  Further, since a chemical reaction occurs only in a region close to the blade 15, a fine groove pattern can be easily formed. Furthermore, since the chemical reaction occurs only while the blade 15 and the workpiece 13 are close to each other, it is possible to easily control the processing amount such as cutting or groove formation.

  More specifically, the method of the present embodiment is a catalyst-assisted chemical processing method, in which reactive species are created only on the reference surface (catalyst), the reactive species are deactivated when leaving the reference surface, and the reference surface The physical properties of these materials have the feature that they do not change for a long time. Since it has such characteristics, the present embodiment has the following advantages.

  That is, since reactive species are created only on the reference surface, unlike conventional chemical etching, processing can be performed without being affected by the surface index of the surface of the workpiece 13. In addition, since the reactive species are inactivated when they are separated from the reference surface, a processing method for transferring the reference surface is provided, and processing on an atomic scale is possible. Furthermore, since the physical properties of the reference surface do not change for a long time, even if the reference surface is transferred and processing proceeds, the surface of the reference surface does not change. For this reason, in the present embodiment, it is possible to efficiently form an ultra-precise groove or to obtain a smooth cut surface.

In particular, when the workpiece 13 is a SiC substrate and the oxidizing agent is H ₂ O ₂ , when the blade 15 is made of Fe, more radicals are generated and more efficient than other transition metals. Can be processed automatically.

  Hereinafter, specific examples of the present invention will be described.

Example 1
As Example 1, single crystal SiC was cut by the blade 15 made of Fe shown in FIG. First, a single crystal SiC wafer is fixed as a sample on the upper surface of the holding table 13, the processing head 14 is disposed so that the blade 15 faces the SiC wafer, and the container 11 is filled with H ₂ O ₂ having a concentration of 30%. It was. Subsequently, the machining head 14 was reciprocated horizontally with respect to the SiC wafer surface using a motor to cut the SiC wafer. At this time, new H ₂ O ₂ was always supplied to the processed part. The processing conditions are as follows.
Condition solution (concentration): H ₂ O ₂ (stock solution (30%))
Catalyst (purity): Fe (99.5%)
Workpiece: 4H-SiC (Si) surface scanning speed: 5 mm / s
Load: 200g

(Comparative Examples 1 and 2)
In Comparative Example 1, a cutting experiment using a diamond blade was performed under predetermined conditions. In Comparative Example 2, a commercially available substrate was used.

  4A and 4B are diagrams each showing a cut surface after the experiment. 4A shows a cut surface in the case of the example using the Fe blade, and FIG. 4B shows the cut surface in the case of the comparative example 1 using the diamond blade.

  When a diamond blade is used (FIG. 4B), the cut surface is damaged and has irregularities on the surface. On the other hand, when the Fe blade of this example was used (FIG. 4A), no traces of cracks or damage were seen on the surface of the cut surface, and the surface had a smooth surface without irregularities. I understand that.

(Example 2)
As Example 2, a groove was formed in single crystal SiC using an Fe blade. The detailed processing conditions were the same as in Example 1 above. FIG. 5 shows the result.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above embodiment, the blade 15 is used as the processing member made of the catalyst metal, but a wire may be used instead of the blade. In addition, a predetermined current may be supplied to the wire, whereby the active species can be generated more efficiently, and processing efficiency such as formation of grooves is improved.

It is a figure showing schematic structure of the processing apparatus which concerns on one embodiment of this invention. It is process drawing for demonstrating the effect | action of the processing apparatus shown in FIG. It is a figure showing the cutting of a workpiece, and the groove formation condition. It is a figure showing the result of a cutting experiment. It is a figure showing the result of a groove formation experiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Processing apparatus, 11 ... Container, 12 ... Holding stand, 13 ... Workpiece, 14 ... Processing head, 15 ... Blade (working member), 16 ... Active species, 17 ... Surface atom of work piece 13, 18 ... Oxides, 19 ... oxidant molecules, 20 ... residual molecules.

Claims (8)

A holding table for holding the workpiece;
A blade-like workpiece formed of a transition metal and brought into contact with or in close proximity to the surface of the workpiece;
An oxidizing agent supplying means for supplying an oxidizing agent to a portion of the processing member facing the workpiece;
Drive means for holding the processing member and reciprocally moving the processing member relative to the workpiece along the longitudinal direction of the processing member;
Cutting the workpiece or forming a groove in the workpiece ;
The oxidizing agent is H ₂ O ₂ (hydrogen peroxide);
The processed member is formed of at least one of Fe (iron), Ni (nickel), Co (cobalt), Cu (copper), Cr (chromium), and Ti (titanium), and
The processing apparatus is characterized in that the workpiece is made of any one of crystalline SiC, sintered SiC, GaN, AlN, sapphire, ruby, and diamond . Including a container containing a solution containing an oxidant;
The processing apparatus according to claim 1, wherein the processing member cuts or forms a groove in the container. The processing apparatus according to claim 1, wherein the processing member is formed of Fe, and the workpiece is a SiC substrate or a GaN substrate. The processing apparatus according to claim 1 , wherein the processing member is reciprocated while an electric current is passed through the processing member. A blade-shaped processing member formed of a transition metal is brought into contact with or in close proximity to the surface of the workpiece, and an oxidizing agent is supplied to a portion of the processing member facing the workpiece, and the processing member is It is a method of cutting the workpiece or forming a groove in the workpiece by relatively reciprocating the workpiece along the longitudinal direction of the workpiece .
The oxidizing agent is H ₂ O ₂ (hydrogen peroxide);
The processed member is formed of at least one of Fe (iron), Ni (nickel), Co (cobalt), Cu (copper), Cr (chromium), and Ti (titanium), and
The processing method is characterized in that the workpiece is made of any one of crystalline SiC, sintered SiC, GaN, AlN, sapphire, ruby, and diamond . The processing method according to claim 5 , wherein cutting or groove formation of the workpiece is performed in an oxidizing agent solution. Processing method of claim 5, before Symbol workpiece is formed by Fe, and the workpiece, characterized in that a SiC substrate or a GaN substrate. The processing method according to claim 5 , wherein the processing member is reciprocated while an electric current is applied to the processing member.

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