Method for processing synthetic quartz glass substrates

Abstract

The present invention relates to a processing method of synthetic quartz glass substrates. By bringing the surface of a synthetic quartz glass substrate as a workpiece into contact with the surface of a protective member made of synthetic quartz glass and laminating the surface of the synthetic quartz glass substrate on the surface of the protective member, optical contact bonding of the workpiece and the protective member is achieved, and a cutting tool is passed through the optical contact bonding surface to process the synthetic quartz glass substrate. This processing method can effectively prevent the generation of microdefects at the entry and exit portions of the cutting tool during the cutting operation. Furthermore, the workpiece and the protective member are not connected using a fixing agent, and thus productivity is high because there is no need to apply a fixing agent and then remove the fixing agent.

Description

[0001] Cross-reference to related applications

[0002] This non-provisional application claims priority to Japanese Patent Application No. 2020-179551, filed on October 27, 2020, pursuant to 35 U.SC §119(a), the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a method for processing synthetic quartz glass substrates. Background Technology

[0004] Synthetic quartz glass substrates used in applications such as microfluidics, microlens arrays, semiconductor substrates, and optical components are provided for use after being processed to form features such as through holes, non-through holes, trenches, and steps. Such processing is typically performed using tools such as grinding wheels or drills. During processing, micro-defects such as debris, burrs, and cracks occur at openings in the workpiece, such as tool entry and tool exit points. These micro-defects are the cause of problems in various applications. For example, in microfluidics, problems such as flow path blockage, reduced analytical accuracy, and foreign material contamination can occur. In semiconductor substrates, stress concentration occurs in areas of micro-defects during the manufacturing process, which can sometimes lead to problems such as substrate failure.

[0005] In cases where through-holes are to be formed in a substrate, to prevent the generation of micro-defects at the tool entry point, such problems are usually solved by processing the substrate together with a cover plate placed against the side of the substrate to be processed. For example, JP-A S61-288940 teaches a method of laminating an aluminum alloy cover plate to the workpiece using an adhesive and machining the workpiece together with the cover plate.

[0006] JP-A 2011-111370 describes a method for manufacturing glass plates using a drilling process. This process creates a through-hole in the glass plate by advancing a first drill bit in the thickness direction from one side of the glass plate while cutting to form a non-through hole, then retracting the initial drill bit and advancing a second drill bit from the other side of the glass plate along the same axis as the first drill bit during cutting. In this drilling process, at least one drill bit has a body with a constant diameter in the axial direction, a small-diameter portion located on the drill bit base end side of the body and having a diameter smaller than the body, and a connecting portion connecting the body and the small-diameter portion. Additionally, one of the drill bits has cutting capability in a region extending from the drill tip to at least the body side of the connecting portion. When one drill bit advances to its maximum depth, the connecting portion reaches the inner side of the glass plate in the thickness direction. This method is reportedly used to prevent debris from forming at the opening.

[0007] However, in the method described in JP-A S61-288940, the cover plate is placed against the workpiece at the tool entry point. Because an adhesive is used to fix the cover plate, micro-defects occur due to the gap between the workpiece and the cover plate formed by the adhesive layer. It is difficult to prevent such defects. Furthermore, it is not possible to completely prevent micro-defects from appearing at the tool exit point. Additionally, the method of using a fixative such as an adhesive or coagulant to fix the cover plate and the substrate requires a fixative application step and a fixative removal step, which is disadvantageous in terms of productivity.

[0008] As for the through-hole forming method disclosed in JP-A 2011-111370, it requires production equipment capable of advancing a first drill bit and a second drill bit on the same axis, as well as additional specially shaped drill bits. Furthermore, preventing the formation of even smaller micro-defects is difficult. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide a processing method for synthetic quartz glass substrates that minimizes defect formation and has excellent productivity.

[0010] As a result of extensive research, the inventors have discovered that when processing synthetic quartz glass substrates, by optically contacting and joining the synthetic quartz glass surfaces together before cutting, the formation of micro-defects at the entry and exit points of the cutting tool during processing can be suppressed at the joined surfaces. Furthermore, because no fixative is used in the optical contact joining, the synthetic quartz glass surfaces can be separated without additional steps after processing. Therefore, processing with minimal defects and high productivity can be performed.

[0011] Therefore, one aspect of the present invention relates to a method for processing a synthetic quartz glass substrate, the method comprising the steps of: providing a synthetic quartz glass substrate as a workpiece; providing a protective member of the workpiece, the protective member being made of synthetic quartz glass; optically contacting the workpiece and the protective member by contacting the surface of the protective member with the surface of the workpiece and stacking the surface of the protective member on the surface of the workpiece; and cutting the synthetic quartz glass substrate by moving a cutting tool from the protective member side through the optical contacting surface to the synthetic quartz glass substrate side and / or from the synthetic quartz glass substrate side through the optical contacting surface to the protective member side.

[0012] In a first aspect of the invention, the optical contact bonding surface of the synthetic quartz glass substrate with the protective member and the optical contact bonding surface of the protective member with the synthetic quartz glass substrate each have an arithmetic mean roughness (Ra) of 1 nm or less.

[0013] A second aspect of the present invention relates to a method for processing a synthetic quartz glass substrate, the method comprising the steps of: providing a plurality of synthetic quartz glass substrates; optically contacting and bonding the plurality of synthetic quartz glass substrates by contacting and stacking the surfaces of the respective synthetic quartz glass substrates to produce a workpiece; providing at least two protective members of the workpiece, the protective members being made of synthetic quartz glass; optically contacting and bonding the workpiece and the protective members by contacting the surface of the protective members with the surface of the workpiece and stacking the surface of the protective members on the surface of the workpiece; and cutting the synthetic quartz glass substrate by using a cutting tool to cut from one protective member side through its optical contact bonding surface to the workpiece side at the synthetic quartz glass substrate furthest from the protective member and from the synthetic quartz glass substrate furthest from the protective member through its optical contact bonding surface to the other protective member side.

[0014] In a second aspect of the invention, each of the optical contact bonding surfaces between synthetic quartz glass substrates in the workpiece, the optical contact bonding surfaces between the workpiece and the protective component, and the optical contact bonding surfaces between the protective component and the workpiece has an arithmetic mean roughness (Ra) of 1 nm or less.

[0015] Beneficial effects of the invention

[0016] This invention effectively prevents the formation of micro-defects at the entry and exit points of the cutting tool during cutting operations. Furthermore, it joins the workpiece and protective components together without the use of a fixing agent, resulting in high productivity because there is no need to apply and subsequently remove the fixing agent. Attached Figure Description

[0017] Figure 1 This is a laser micrograph of the cutting tool entry portion at the non-through hole formed in the synthetic quartz glass substrate in Example 1.

[0018] Figure 2 Laser micrographs showing the through-holes formed in the synthesized quartz glass substrate in Example 2. Figure 2 (A) Displays the cutting tool entry point and Figure 2 (B) Shows the part where the cutting tool has disengaged.

[0019] Figure 3 Laser micrographs showing the through-holes formed in the synthesized quartz glass substrate in Example 3. Figure 3 (A), 3(C), 3(E), and 3(G) each display the cutting tool entry portion in the first to fourth substrates and Figure 3 (B), 3(D), 3(F) and 3(H) each show the cutting tool removal portion in the first to fourth substrates.

[0020] Figure 4 This is a laser micrograph of the cutting tool entry portion at a non-through hole formed in a synthetic quartz glass substrate in Comparative Example 1.

[0021] Figure 5 This shows a laser micrograph of the through-hole formed in the synthetic quartz glass substrate in Comparative Example 2. Figure 5 (A) Displays the cutting tool entry point and Figure 5 (B) Shows the part where the cutting tool has disengaged. Detailed Implementation

[0022] The objects, features, and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0023] As indicated above, a first aspect of the processing method for a synthetic quartz glass substrate of the present invention includes the following steps: providing a synthetic quartz glass substrate as a workpiece; providing a protective member made of synthetic quartz glass; optically contacting the workpiece and the protective member by contacting the surface of the protective member with the surface of the workpiece and stacking the surface of the protective member on the surface of the workpiece, thereby typically forming an assembly in which the workpiece and the protective member are connected at an optical contacting surface and the assembly has a protective member side and a synthetic quartz glass substrate (workpiece) side; and cutting the synthetic quartz glass substrate by causing a cutting tool to pass from the protective member side through the optical contacting surface to the synthetic quartz glass substrate side and / or from the synthetic quartz glass substrate side through the optical contacting surface to the protective member side.

[0024] A second aspect of the method for processing a synthetic quartz glass substrate of the present invention includes the following steps: providing a plurality of synthetic quartz glass substrates; optically contacting and stacking the surfaces of the plurality of synthetic quartz glass substrates to produce a workpiece; providing a protective member made of synthetic quartz glass; optically contacting and joining the workpiece and the protective member by contacting the surface of the protective member with the surface of the workpiece and stacking the surface of the protective member on the surface of the workpiece, thereby typically forming an assembly in which the synthetic quartz glass substrate and the protective member are connected at their respective optical contacting surfaces and the assembly has one protective member side and another protective member side; and cutting the synthetic quartz glass substrate by using a cutting tool to cut from one protective member side through its optical contacting surface to the workpiece side of the synthetic quartz glass substrate furthest from the one protective member and from the synthetic quartz glass substrate furthest from the one protective member through its optical contacting surface to the other protective member side.

[0025] The synthetic quartz glass substrate used in this invention can be obtained by: molding a synthetic quartz glass ingot, prepared by an oxyhydrogen flame reaction of a silica-starting compound such as a silane compound or a siloxane compound, into a desired shape; annealing the ingot and then slicing it to a desired thickness; subsequently grinding and edge grinding (if necessary); and then coarse and fine polishing. The synthetic quartz glass substrate can be prepared by known methods and is not particularly limited thereto.

[0026] The synthetic quartz glass substrate can have any suitable shape, such as a square or circular shape. For example, in square glass substrates, square glass substrates with dimensions of 10×10mm to 300×300mm are preferred. In circular glass substrates, circular glass substrates with a diameter of 10-300mm are preferred. The thickness of the synthetic quartz glass substrate can be suitably selected, but the thickness of the synthetic quartz glass substrate is preferably at least 0.01mm, more preferably at least 0.05mm, and even more preferably at least 0.1mm, and preferably 300mm or less, more preferably 100mm or less, and even more preferably 30mm or less.

[0027] One or both surfaces of the synthetic quartz glass substrate (the surfaces to be optically contacted) should have a degree of flatness that makes optical contact possible, and its arithmetic mean roughness (Ra) is preferably 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.3 nm or less. An arithmetic mean roughness (Ra) within this range maintains tight adhesion of the optical contact bonding surfaces, avoiding problems such as the inability to stack and fix the substrates via optical contact or insufficient bonding forces that cause delamination during processing. In practice, the arithmetic mean roughness (Ra) can be measured using atomic force microscopy (AFM).

[0028] A single synthetic quartz glass substrate can be provided as a workpiece, or multiple (two or more) synthetic quartz glass substrates can be provided and used together as workpieces. When multiple synthetic quartz glass substrates are used as workpieces, the workpiece is effectively formed by stacking the multiple substrates so that their surfaces come into contact with each other and optically bond the individual substrates. By adopting this arrangement, multiple synthetic quartz glass substrates can be processed at once, thereby achieving even better processing productivity. Considering the adverse effects on optical contact related to increased warpage of the synthetic quartz glass substrates when a large number of substrates are stacked together, the number of stacked synthetic quartz glass substrates is preferably no more than 50, and more preferably no more than 20.

[0029] Multiple synthetic quartz glass substrates are optically contacted and bonded by bringing their surfaces close together. In this way, the synthetic quartz glass substrates are stacked and secured to each other. As used herein, "optical contact" refers to a technique that joins smooth glass surfaces together simply by pressing them together and bringing them close to each other. Such bonding depends on van der Waals forces between the glass surfaces or on hydrogen bonds between surface silanol groups formed due to adsorbed water.

[0030] Before bringing the surfaces of the synthetic quartz glass substrate close together via optical contact, it is preferable to clean the substrate. Cleaning can be performed by any method capable of removing particles with a size of 100 μm or larger. Examples include methods using pure water, alcohol solutions, acidic solutions such as sulfuric acid, alkaline solutions such as ammonia, or surfactants. Cleaning can be performed by a single method or by combining multiple methods. Ultrasonic cleaning can also be used in conjunction with these methods.

[0031] The protective component made of synthetic quartz glass used in this invention can be obtained by: molding a synthetic quartz glass ingot, prepared by an oxyhydrogen flame reaction of a silica-starting compound such as a silane compound or a siloxane compound, into a desired shape; annealing the ingot and cutting it to the desired dimensions (e.g., slicing it to the desired thickness); then grinding and edge grinding (if necessary); and subsequently coarse and fine polishing. The protective component made of synthetic quartz glass can be prepared by known methods and is not particularly limited.

[0032] The protective component made of synthetic quartz glass is an auxiliary component used when processing the synthetic quartz glass substrate and can have any suitable shape, such as square or round. For example, among the square-shaped protective components, those with dimensions of 10×10mm to 300×300mm are preferred. Among the round protective components, those with a diameter of 10-300mm are preferred. The thickness of the protective component made of synthetic quartz glass is appropriately selected. However, considering that the time spent cutting the protective component during processing affects productivity and makes it easier to separate the protective component from the synthetic quartz glass substrate afterwards, the thickness is preferably at least 0.01mm, more preferably at least 0.1mm, and even more preferably at least 0.2mm, and preferably not greater than 300mm, more preferably not greater than 100mm, and even more preferably not greater than 10mm. The protective component made of synthetic quartz glass is preferably in the form of a plate (sometimes called a "cover plate").

[0033] At least one surface (optical contact bonding surface) of the protective component made of synthetic quartz glass should have a flatness sufficient for optical contact, and its arithmetic mean roughness (Ra) is preferably 1 nm or less, more preferably 0.5 nm or less, and even more preferably 0.3 nm or less. An arithmetic mean roughness (Ra) within this range maintains tight adhesion of the optical contact bonding surface, thus avoiding problems such as the inability to stack and fix substrates via optical contact or insufficient bonding forces that allow delamination to occur during processing.

[0034] The number of protective components made of synthetic quartz glass provided is typically one or two. For example, when a non-through hole is to be formed in a synthetic quartz glass substrate, a single protective component can be used. When a through hole is to be formed in a synthetic quartz glass substrate, although it is preferable to use two protective components during processing, a single protective component can be used. When necessary, three or more protective components made of synthetic quartz glass can be used.

[0035] Optical contact bonding is achieved by bringing the surface of a synthetic quartz glass substrate close to the surface of a protective component made of synthetic quartz glass. In this manner, the protective component is stacked on top of the workpiece, thereby securing the workpiece and the protective component to each other.

[0036] Before bringing the synthetic quartz glass substrate (the workpiece) and the protective component made of synthetic quartz glass close together via optical contact, it is preferable to clean each synthetic quartz glass substrate and the protective component made of synthetic quartz glass. Cleaning can be performed by any method capable of removing particles with a size of 100 μm or larger. Examples include methods using pure water, alcohol-based solutions, acidic solutions such as sulfuric acid, alkaline solutions such as ammonia, or surfactants. Cleaning can be performed by a single method or by combining multiple methods. Ultrasonic cleaning can also be used in conjunction with these methods.

[0037] In this invention, features such as holes, cracks, trenches, and steps are formed in a synthetic quartz glass substrate according to the intended application, such as microfluidics, microlens arrays, semiconductor substrates, and optical components.

[0038] In practice, when processing a single synthetic quartz glass substrate into a workpiece, such processing may include any one or two of the following operations:

[0039] (a) The operation of cutting the synthetic quartz glass substrate by moving a cutting tool from the protective component side through the optical contact bonding surface to the synthetic quartz glass substrate side, and

[0040] (b) The operation of cutting the synthetic quartz glass substrate by moving a cutting tool from the synthetic quartz glass substrate side through the optical contact bonding surface to the protective component side.

[0041] Specifically, when forming non-through holes, grooves, steps, etc., processing should be performed, thus including operation (a). When forming through holes, cracks, etc., processing should be performed, thus including both operations (a) and (b). When forming through holes, cracks, etc., and it is acceptable that an opening on only one side is a low defect, processing can be performed by including operation (b) but not operation (a).

[0042] When multiple synthetic quartz glass substrates are processed into workpieces, the synthetic quartz glass substrates can be processed by: providing multiple (usually two) protective components made of synthetic quartz glass, optically contacting one protective component with one surface of the workpiece and optically contacting the other protective component with another surface of the workpiece, and including...

[0043] (c) The operation of cutting a synthetic quartz glass substrate by moving a cutting tool from one side of a protective component through its optical contact mating surface to the workpiece side of the synthetic quartz glass substrate furthest from the protective component, and

[0044] (d) Operation of cutting a synthetic quartz glass substrate by moving a cutting tool from the synthetic quartz glass substrate furthest from one protective component through its optical contact bonding surface to the side of another protective component.

[0045] This method is preferred when through holes, cracks, etc. are formed simultaneously in multiple synthetic quartz glass substrates.

[0046] Machining can be performed using a machining center or other CNC machine tool. Specifically, machining is performed using an abrasive tool composed of diamond abrasive, cubic boron nitride abrasive, etc., fixed to the spindle of a machining center or other CNC machine tool programmed to produce the desired shape via electrodeposition, metal bonding, etc. There are no particular limitations on the grit size of the abrasive tool. However, for machining accuracy and productivity, the grit size is preferably at least #20, and especially #100 or larger, but preferably not greater than #5000, and especially not greater than #2000. There are no particular limitations on the spindle speed of the abrasive tool; for machining accuracy and productivity, at least 100 rpm is preferred, and especially at least 1,000 rpm, but preferably not greater than 70,000 rpm, and especially not greater than 60,000 rpm. There are also no particular limitations on the feed rate; for machining accuracy and productivity, at least 1 mm / min is preferred, and especially at least 10 mm / min, but preferably not greater than 10,000 mm / min, and especially not greater than 1,000 mm / min. In addition, for purposes such as cooling and debris removal, it is preferable to use emulsion-based, water-soluble, oil-based, or other types of cutting fluids during cutting.

[0047] By using the synthetic quartz glass substrate processing method of the present invention to form features such as holes, cracks, grooves and steps on the synthetic quartz glass substrate for intended applications such as microfluidics, microlens arrays, semiconductor substrates and optical components, the generation of micro-defects at the entry and exit points of the cutting tool during processing can be effectively prevented.

[0048] Example

[0049] The following embodiments and comparative examples are provided to illustrate the present invention, but are not intended to limit the scope of the invention.

[0050] Example 1

[0051] A synthetic quartz glass substrate with a diameter of 150 mm, a thickness of 0.5 mm, and an arithmetic mean roughness (Ra) of 0.3 nm on both polished sides is provided by grinding a slab disc (150 mm in diameter) of synthetic quartz glass with a planetary-motion double-sided grinding machine, followed by coarse polishing with a hard urethane polishing cloth and cerium oxide abrasive using a planetary-motion double-sided polishing machine, and then fine polishing with a goatskin polishing cloth and colloidal silica abrasive using a planetary-motion double-sided polishing machine.

[0052] A single protective element (cover plate) with a diameter of 150 mm, a thickness of 0.5 mm, and an arithmetic mean roughness (Ra) of 0.3 nm on both polished sides is provided in the same manner as a synthetic quartz glass substrate.

[0053] Next, the synthetic quartz glass substrate and the protective components made of synthetic quartz glass are cleaned using an aqueous solution of potassium hydroxide, hot concentrated sulfuric acid, a weak alkaline surfactant, and pure water, and then dried with IPA.

[0054] Then, the polished side of the synthetic quartz glass substrate and the polished side of the protective component made of synthetic quartz glass are brought into contact, stacked, and brought close together to achieve optical contact bonding.

[0055] Next, a hole is formed in the synthetic quartz glass substrate by cutting from the protective component side through the optical contact bonding surface using a machining center, thereby creating a non-through hole with a diameter of 0.5 mm and a depth of 0.3 mm in the synthetic quartz glass substrate. The cutting process is a helical process using a water-soluble cutting fluid under the following processing conditions.

[0056] Processing conditions

[0057] Cutting tool: Electrodeposited diamond grinding wheel (AAR07, from FSK KK)

[0058] Abrasive grain size: #600

[0059] Spindle speed: 20,000 rpm

[0060] Cutting conveyor speed: 40mm / min

[0061] Spiral wire: 0.002mm

[0062] Figure 1 Laser micrograph showing the tool entry point of a non-through-hole formed in a synthetic quartz glass substrate. No microdefects were observed at the tool entry point of the non-through-hole formed in the synthetic quartz glass substrate.

[0063] Example 2

[0064] A synthetic quartz glass substrate and two protective components (covers) made of synthetic quartz glass are provided in the same manner as in Example 1.

[0065] The synthetic quartz glass substrate and the protective component made of synthetic quartz glass were then cleaned and dried in the same manner as in Example 1.

[0066] Next, one polished side of the synthetic quartz glass substrate is brought into contact with the polished side of the first protective component made of synthetic quartz glass, and the other polished side of the synthetic quartz glass substrate is brought into contact with the polished side of the second protective component made of synthetic quartz glass. These are then stacked and brought close together to achieve optical contact bonding.

[0067] Using a machining center similar to that in Example 1, cutting is performed under the same processing conditions as in Example 1, forming a hole from one protective substrate side through two optical contact joint surfaces to reach another protective component, thereby creating a through hole with a diameter of 0.5 mm in the synthetic quartz glass substrate.

[0068] here, Figure 2 Laser micrograph showing a through-hole formed in a synthetic quartz glass substrate. Figure 2 (A) Displays the cutting tool entry point and Figure 2 (B) The cutting tool disengagement area is shown. No micro-defects were observed at the cutting tool entry or disengagement area of ​​the through-hole formed in the synthetic quartz glass substrate.

[0069] Example 3

[0070] Four synthetic quartz glass substrates and two protective components (covers) made of synthetic quartz glass are provided in the same manner as in Example 1.

[0071] The synthetic quartz glass substrate and the protective component made of synthetic quartz glass were cleaned and dried in the same manner as in Example 1.

[0072] Next, the polished sides of the four synthetic quartz glass substrates are brought into contact with each other, stacked, and brought close together to achieve optical contact bonding. In this case, three optical contact bonding surfaces are thus formed.

[0073] Next, one of the remaining polished surfaces of the synthetic quartz glass substrate is brought into contact with the polished surface of the first protective component made of synthetic silica glass, and the other remaining polished surface of the synthetic quartz glass substrate is brought into contact with the polished surface of the second protective component made of synthetic quartz glass. The components are then stacked and brought close together to achieve optical contact bonding.

[0074] Using a machining center similar to that in Example 1, cutting is performed under the same processing conditions as in Example 1, forming a hole from one protective substrate side through five optical contact bonding surfaces to reach another protective component, thereby creating a through hole with a diameter of 0.5 mm in each of the four synthetic quartz glass substrates.

[0075] Figure 3 Laser micrograph showing a through-hole formed in a synthetic quartz glass substrate. Figure 3 (A) Shows the cutting tool entry portion in the first synthetic quartz glass substrate from the tool entry side, and Figure 3 (B) Shows the cutting tool detachment portion in the first synthetic quartz glass substrate from the tool entry side. Figure 3 (C) Shows the cutting tool entry portion in the second synthetic quartz glass substrate from the tool entry side, and Figure 3 (D) shows the cutting tool detachment portion in the second synthetic quartz glass substrate from the tool entry side. Figure 3 (E) Shows the cutting tool entry portion in the third synthetic quartz glass substrate from the tool entry side, and Figure 3 (F) shows the cutting tool detachment portion in the third synthetic quartz glass substrate from the tool entry side. Figure 3 (G) Shows the cutting tool entry portion in the fourth synthetic quartz glass substrate from the tool entry side, and Figure 3 (H) shows the cutting tool disengagement portion in the fourth synthetic quartz glass substrate from the tool entry side. No microdefects were observed at either the cutting tool entry or disengagement portion in the through-hole formed in the synthetic quartz glass substrate.

[0076] Comparative Example 1

[0077] A synthetic quartz glass substrate and a protective component (cover plate) made of synthetic quartz glass were prepared in the same manner as in Example 1.

[0078] The synthetic quartz glass substrate and the protective component made of synthetic quartz glass were cleaned and dried in the same manner as in Example 1.

[0079] Next, the polished surface of the synthetic quartz glass substrate and the polished surface of the protective component made of synthetic quartz glass were connected using a Shiftwax 582W from Nikka Seiko Co., Ltd.

[0080] Using a machining center similar to that in Example 1, cutting is performed under the same machining conditions as in Example 1, and a hole is formed from the protective component side through the area connected with wax to the synthetic quartz glass substrate, thereby creating a non-through hole with a diameter of 0.5 mm and a depth of 0.3 mm in the quartz glass substrate.

[0081] Figure 4 This is a laser micrograph of the tool entry portion of a non-through-hole formed in a synthetic quartz glass substrate. Multiple debris particles with a maximum size of 22 μm were observed at the tool entry portion.

[0082] Comparative Example 2

[0083] A synthetic quartz glass substrate and two protective components (covers) made of synthetic quartz glass were prepared in the same manner as in Example 1.

[0084] The synthetic quartz glass substrate and the protective component made of synthetic quartz glass were cleaned and dried in the same manner as in Example 1.

[0085] Next, using a Shiftwax 582W from Nikka Seiko Co., Ltd., one of the polished surfaces of the synthetic quartz glass substrate was connected to the polished surface of the first protective member made of synthetic quartz glass, and another polished surface of the synthetic quartz glass substrate was connected to the polished surface of the second protective member made of synthetic quartz glass.

[0086] Using a machining center similar to that in Example 1, cutting is performed under the same machining conditions as in Example 1, forming a hole from one protective component side through an area connected with wax to another protective component, thereby creating a through hole with a diameter of 0.5 mm in the quartz glass substrate.

[0087] Figure 5 Laser micrograph showing through-holes formed in a synthetic quartz glass substrate. Figure 5 (A) Displays the cutting tool entry point and Figure 5 (B) The tool break-out area is shown. Multiple chips with a maximum size of 31 μm were observed at the tool entry point. Additionally, at the tool break-out area, cracks with a width of up to 46 μm were observed in a wide area around the opening.

[0088] As can be seen from the above results, the processing method of the present invention can effectively prevent the generation of micro-defects.

Claims

1. A method for processing synthetic quartz glass substrates, comprising the following steps: Provide synthetic quartz glass substrates as workpieces; Provide a protective component for the workpiece, the protective component being made of synthetic quartz glass; Optical contact bonding is achieved by bringing the surface of the protective component into contact with the surface of the workpiece and stacking the surface of the protective component on the surface of the workpiece. and The synthetic quartz glass substrate is cut by moving a cutting tool from the protective component side through the optical contact bonding surface to the synthetic quartz glass substrate side, or from the protective component side through the optical contact bonding surface to the synthetic quartz glass substrate side and from the synthetic quartz glass substrate side through the optical contact bonding surface to the protective component side.

2. The processing method according to claim 1, wherein the optical contact bonding surface of the synthetic quartz glass substrate with the protective member and the optical contact bonding surface of the protective member with the synthetic quartz glass substrate each have an arithmetic mean roughness (Ra) of 1 nm or less.

3. The processing method according to claim 2, wherein the arithmetic mean roughness (Ra) is 0.5 nm or less.

4. The processing method according to claim 1, wherein the thickness of the synthetic quartz glass substrate is from 0.1 mm to 30 mm.

5. The processing method according to claim 1, wherein the thickness of the protective component is 0.2 mm to 10 mm.

6. The processing method according to claim 1, wherein during the cutting step, through holes or cracks are formed in the synthetic quartz glass substrate.

7. The processing method according to claim 1, wherein in the cutting step, non-through holes or trenches are formed in the synthetic quartz glass substrate.

8. A method for processing synthetic quartz glass substrates, comprising the following steps: Provide synthetic quartz glass substrates as workpieces; Provide a protective component for the workpiece, the protective component being made of synthetic quartz glass; Optical contact bonding is achieved by bringing the surface of the protective component into contact with the surface of the workpiece and stacking the surface of the protective component on the surface of the workpiece. and The synthetic quartz glass substrate is cut by a cutting tool from the synthetic quartz glass substrate side through the optical contact bonding surface to the protective component side, wherein... Through holes or cracks are formed in both the synthetic quartz glass substrate and the protective component.

9. A method for processing a synthetic quartz glass substrate, comprising the following steps: Multiple synthetic quartz glass substrates are available; Multiple synthetic quartz glass substrates are optically joined by contacting and stacking their surfaces, thereby producing a workpiece. Provide at least two protective components for the workpiece, the protective components being made of synthetic quartz glass; Optical contact bonding is achieved by bringing the surface of the protective component into contact with the surface of the workpiece and stacking the surface of the protective component on the surface of the workpiece. and The synthetic quartz glass substrate is cut by moving a cutting tool from one protective component side through its optical contact joint surface to the workpiece side of the synthetic quartz glass substrate furthest from the protective component, and from the synthetic quartz glass substrate furthest from the protective component through its optical contact joint surface to the other protective component side.

10. The processing method according to claim 9, wherein the optical contact bonding surface between the synthetic quartz glass substrates in the workpiece, the optical contact bonding surface between the workpiece and the protective member, and the optical contact bonding surface between the protective member and the workpiece each have an arithmetic mean roughness (Ra) of 1 nm or less.

11. The processing method according to claim 10, wherein the arithmetic mean roughness (Ra) is 0.5 nm or less.

12. The processing method according to claim 9, wherein the thickness of the synthetic quartz glass substrate is from 0.1 mm to 30 mm.

13. The processing method according to claim 9, wherein the thickness of the protective component is 0.2 mm to 10 mm.

14. The processing method according to claim 9, wherein during the cutting step, through holes or cracks are formed in the synthetic quartz glass substrate.

15. The processing method according to claim 9, wherein during the cutting step, through holes or cracks are formed in both the synthetic quartz glass substrate and the protective component.

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