JPH01215960A - Manufacture of aluminum alloy substrate - Google Patents

Abstract

PURPOSE:To obtain an Al-alloy substrate reduced in strain variation due to heating by subjecting a disk of Al alloy containing specific amounts of Mg and Mn to outside diameter working, to softening treatment, and successively to partial cutting of the disk and to surface finishing. CONSTITUTION:A disk of an Al alloy containing 2-5% Mg and 0.1% Mn is subjected to disk outside diameter working and then to softening treatment. Successively, a part of the disk is cut off, and surface finish working is applied to the above disk. By this method, the Al-alloy substrate in which strain after working is reduced and also the increase in strain due to subsequent heat treatment is regulated to <=10mum can be obtained. This Al-alloy substrate is used for film formation, semiconductor substrate grinding and supporting, etc.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to the production of aluminum alloy substrates for film formation and semiconductor substrate polishing support, and in particular to the production of aluminum alloy substrates that exhibit little strain change during surface finishing and heating used in vacuum film formation, etc. It's about how to do it. (Prior art) A silicon substrate is typically used as a semiconductor element substrate, and by adding impurities it becomes a P-type or N-type semiconductor, and by oxidizing the surface, an insulating film can be easily formed. It has characteristics such as being able to In recent years, S OI (S
I n5ulator) technology or W S I (W
New technologies such as aferScale integration) technology are attracting attention. Generally, when devices are formed on a silicon wafer, only the surface layer is used as an active layer. In order to improve device performance, it is sufficient to utilize only this surface layer, and SO technology is used for this purpose. For example, [Nikkei Elec 1 ~ Ronix J, 1
As already stated in the October 6, 1986 issue, p. 76, in order to improve the performance of devices formed on silicon wafers, a polishing support substrate is pasted on the device after preliminary formation. After polishing the silicon layer on the back of the device to leave only the active layer, the polishing support substrate is peeled off and another substrate is attached to the thinned silicon wafer (for example,
S○ placing silicon on a silicon substrate via an insulating layer
■There is a structure). In this case, a silicon wafer is used as the polishing support substrate, and the same silicon wafer as the silicon wafer on which the element is formed is required, which causes an increase in the element price. Furthermore, the substrate to which the thinned silicon wafer is attached is required to have good heat dissipation properties, considering the heat generated by the elements. Next, when looking at solar cells, which are attracting attention for their energy-saving properties, their structures can be broadly divided into crystalline solar cells and amorphous solar cells. In the case of a crystalline solar cell, a solar cell is formed on the substrate itself, whereas in an amorphous solar cell, a solar cell is formed on a metal or insulating substrate by a wet or dry method. Typical dry methods include plasma C, V, and D.
, (chemical vapor deposition) method, a, D, (glow discharge) method, etc., but all methods require heating of the substrate in order to improve performance. In this case, it is necessary that the increase in distortion of the substrate due to heat be small. Generally, glass is used as the insulating substrate, and stainless steel is used as the metal substrate. In the case of glass, it is effective for consumer use such as calculators, but if a large amount of power is required, a large area is required, and there is a risk of breaking due to the nature of glass. There are reliability issues. Stainless steel is used to solve these problems, but it is more expensive than glass, and when considering applications such as space, it is heavy and requires a huge amount of energy to transport. becomes. (Problems to be Solved by the Invention) When looking at each of the nine uses, there are the above problems, but overall, silicon is expensive for polishing support substrates, and there are problems such as easy shortage. Therefore, there are problems with heat dissipation and the like in bonded substrates. Further, in the case of solar cell substrates, there are problems such as glass being easily broken and stainless steel being expensive and heavy. The characteristics commonly required for these substrates are low distortion after surface finishing and small increase in strain before and after heat treatment.When considering substrates made of materials other than those listed above, these characteristics are required. It must satisfy the characteristics. Furthermore, considering that the conventional equipment can be used as is, it is necessary to make the shape the same as that of the silicon wafer. Conventionally, attempts have been made to use aluminum alloys, which are inexpensive, lightweight, easy to process, and have high thermal conductivity, as well as high heat dissipation properties, as a substrate material that satisfies these characteristics. The reality is that it has not been released. The present invention was made in view of the above circumstances, and
The object of the present invention is to provide a method for manufacturing an aluminum alloy substrate that has small distortion after surface finishing and a small increase in distortion before and after heat treatment. (Means for Solving the Problems) In order to achieve the above object, the present inventors conducted various studies on the alloy composition and manufacturing process in the conventional aluminum alloy substrate manufacturing method, and as a result, they appropriately adjusted the composition and improved the manufacturing process. It has been discovered that by specifying the order of the above, strain changes, particularly strain changes due to heating, can be minimized as much as possible, and the present invention has now been completed. That is, in the present invention, Mg: 2 to 5% and Mn: 0.1
% or more, with the remainder consisting of AQ and unavoidable impurities. After processing the outer diameter of the disc and softening it in an appropriate order, cut a portion of the disc → perform surface finishing processing in this order. By applying this process, the distortion after surface finishing is small and the increase in distortion due to subsequent heat treatment is 10%.
The gist of the present invention is a method for manufacturing an aluminum alloy substrate for film formation and for supporting semiconductor substrate polishing, which is characterized by obtaining an aluminum alloy substrate with a size of .mu.m or less. The present invention will be explained in more detail below. Conventionally, for example, Afl-Mg alloys have been widely used as aluminum alloys for magnetic disks, but improvements in recording density require surface precision of the substrate surface, and crystallized substances have become important. High purity aluminum base Afl-M
g-binary alloys have been used. When manufacturing magnetic disks, for example, in the sputtering γ-Fe203 method, a heat treatment of 300°C or more is performed in the process, and the film is generally formed on an alumite substrate, but there may be a difference in the alumite film thickness on both sides, or the aluminum The fact that the alloy substrate itself is distorted by the heat during the heat treatment is a cause of modulation errors and the like. According to the research conducted by the present inventors, it was confirmed that when heat-treating the AQ-Mg binary alloy, the occurrence of strain differs depending on the method of supporting the substrate, the direction of the heat source, etc.
It has been found that it is difficult to use such alloys as semiconductor substrate polishing support substrates or film forming substrates that require high precision and device performance. Therefore, as a result of further intensive research on this countermeasure, we found that AQ
The present invention uses a -Mg-Mn ternary alloy. First, the reasons for limiting the chemical components in the present invention will be explained. Mg is an essential element for imparting predetermined mechanical properties and workability to the substrate, but the effect cannot be obtained unless it is added in an amount of 2% or more. However, if it exceeds 5%, M
The amount of G-8i type products increases, and non-metallic inclusions (MgO) are generated due to high temperature oxidation during melting and casting, resulting in a decrease in surface accuracy during finishing processing, making it difficult to use as a substrate for semiconductor substrate polishing support. Otherwise, it becomes useless as a substrate for forming elements. Therefore, the Mg amount is in the range of 2 to 5%. It has been confirmed that Mn is an element that is effective in imparting predetermined mechanical properties and workability as well as increasing corrosion resistance, and is also an element that has the effect of suppressing the occurrence of distortion due to heat treatment in the method of the present invention. Ta. In order to suppress the occurrence of strain, it is necessary to contain at least 0.1% of Mn, and a large amount may be added. However, if it exceeds 0.5%, coarse Afl-Fe-Mn-based products are likely to be generated, which may cause a decrease in surface precision during air finishing, so it is preferably 0.5% or less. . Note that although the aluminum alloy contains impurities due to manufacturing, the amount of impurities is allowed within a limit that does not impair the effects of the present invention. Next, a manufacturing process of an aluminum alloy substrate having the above chemical components will be explained. In the present invention, the above-mentioned aluminum alloy is melted by a conventional method, and after casting, a predetermined aluminum alloy substrate can be obtained by soaking, heating, hot rolling, and cold rolling. Next, in the present invention, this aluminum alloy substrate is subjected to disk outer diameter processing → softening treatment (or softening treatment → disk outer diameter processing) → cutting a portion of the disk → surface finishing processing in this order. . Conventionally, magnetic disk substrates have been produced by punching an aluminum alloy substrate into a donut shape to match a predetermined disk diameter, annealing it to remove distortion to make it a soft material, and then processing the end face, grinding, diamond turning, etc. Surface finishing processes such as cross polishing and electrolytic composite polishing are performed. However, when the present inventors adopted the above-mentioned manufacturing process to manufacture an AQ-Mg-Mn-based aluminum alloy substrate and conducted a test, it was found that depending on which process the process of cutting a part of the disk is inserted, It was confirmed that the occurrence of strain was significantly different. Therefore, as a result of further intensive research,
For example, if the substrate temperature at the time of film formation is 4°C, if annealing is performed at a higher temperature, then a part of the disk is cut and the surface is finished, the strain increase before and after the subsequent heat treatment will be reduced. They discovered that a small amount of aluminum alloy substrates could be obtained and developed this manufacturing process. Therefore, in the case of this manufacturing process, it is important to cut a portion of the aluminum alloy disk after processing the outer diameter of the disk and softening it, but before finishing the surface. It is. Various methods such as shear cutting, milling, laser cutting, and electrical discharge machining can be used to cut a portion of the disk. The conditions and order of the disk outer diameter processing and softening treatment are not particularly limited. As a softening treatment, press annealing, which is performed by applying a load and annealing in the same way as for magnetic disk substrates, is usually sufficient, and the treatment temperature at this time may be higher than the temperature applied during film formation, but at 460°C, aluminum Since the alloy substrates stick to each other and are subjected to stress during peeling, causing distortion, it is preferable to set the processing temperature to 4.60° C. or lower when a mold release agent or the like is not used. Surface finishing processing includes rough finishing processing such as rough cutting and rough grinding, as well as finishing blinding, and in the present invention, any finishing processing is performed after a portion of the disk is cut. Surface finishing processing conditions are not particularly limited. Furthermore, if a process such as surface roughening such as cutting or rough grinding, or cutting a part of the disk is performed before the softening treatment, there is a risk that the load distribution will be uneven when stacking during the softening treatment. Yes, these steps need to be performed after the softening treatment. Note that a soft material may be used before processing the outer diameter of the disk. In the method of the present invention, it is usually desirable to perform the following steps: machining of the outer diameter of a disk, softening treatment, cutting a portion of the disk, rough grinding, and finishing grinding. Next, the present invention will be explained in detail. As a chemical component, Mg is a fixed amount of 3.5%, Mn is added at 0% (no addition), 0.1%, and 0.25%, and the balance is Afl and inevitable impurities. After rolling each of the alloy plates to a thickness of about 1.4 mm,
After punching into a disk of φ and rounding the outer peripheral end surface, 425
Press annealing was performed at ℃ for 2 hours. Next, after (comparative example) or after cutting a part of the disk (inventive example), coarse grain 1
After finishing the surface by performing ~ and finishing grinding, the strain was observed using a surface strain measuring machine (N4DEK). As a result, the strain was approximately 6 μm regardless of the Mn content (ie, composition). Since the plate thickness, plate thickness deviation, surface roughness, etc. are constant, this is thought to be mostly determined by the spacer, since the strain of the spacer used during press annealing is approximately 6 μm. . Therefore, in order to further consider the strain change due to heat treatment, we conducted heat treatment in the atmosphere at 400°C (corresponding to the film formation temperature) for 2 hours under the same heating conditions as during film formation, i.e., holding the disk vertically. was carried out, and then the strain was measured. Table 1 shows the relationship between the negative Mn addition and the increase in strain before and after heat treatment. In addition,
For some products, the annealing conditions were 350° C. for 2 hours. Table 1 As is clear from the results shown in Table 1, when Mn is added, the amount of increase in strain due to heat treatment is smaller than when it is not added, and as the amount of Mn added increases. An even more significant difference can be seen. In addition, the annealing temperature was changed to the heat treatment temperature of 40
When the temperature is 350°C, which is lower than 0°C, the effect of Mn addition becomes smaller as shown in Comparative Example 2, and the effect of Mn addition is exhibited when annealing is performed at a temperature higher than the heating temperature during film formation. Recognize. Example 2 Contains Mn: 0.23% and Mg: 3.5%, the balance is A
An aluminum alloy plate made of fl and unavoidable impurities was produced and rolled to a thickness of about 1.4 mm, and then rolled to a thickness of 15 Q mmφ.
It was punched out into a disc. After rounding the end face. In order to investigate the occurrence of distortion due to the process, according to the manufacturing process shown in Table 2, the disk was processed by changing the order of the annealing process at 425°C for 2 hours and the process of cutting a part of the disk. Rough grinding and finishing grinding were performed to produce an aluminum ram alloy substrate with a thickness of about 1.3 mm and a diameter of 150 mm (same shape as a partially cut silicon wafer). Note that the board thickness, board thickness deviation, and surface roughness of the produced substrates were the same for each board. Next, as in Example 1, the substrate was held vertically and heated for 400 minutes.
'CX The results of 2 hours of heat treatment are also listed in Table 2. As is clear from Table 2, the aluminum alloy substrate produced according to the present invention not only has a small strain after surface finishing, but also a small strain after heat treatment, and also has a small increase in strain before and after heat treatment. On the other hand, in all of the comparative examples, a part of the surface finishing process such as rough grinding or rough cutting was performed before the step of partially cutting the disk, so that not only the distortion after the surface finishing but also the distortion after the heat treatment was large. Even if a part of the disc is cut after annealing,
It can be seen that the distortion does not decrease after surface finishing. This shows that the process of the present invention is effective even in the production of substrates for polishing semiconductor substrates, etc. that do not require a heat treatment process.

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(Effects of the Invention) As detailed above, according to the present invention, since an aluminum alloy substrate containing specific amounts of Mg and Mn is used, not only the increase in strain before and after heat treatment during film formation is small, but also By employing the process of processing the outer circumference of the plate → softening process → cutting a portion of the disc → surface finishing process, the distortion after surface finishing can be reduced, and the increase in distortion after heat treatment can also be reduced. Further, since an aluminum alloy is used, excellent effects can be obtained, such as being able to produce a substrate for film formation and semiconductor substrate polishing support that is inexpensive, lightweight, and has high heat dissipation. Patent applicant Hisashi Nakamura, patent attorney representing Kobe Steel, Ltd.

Claims (1)

[Claims] In weight% (hereinafter the same), Mg: 2 to 5% and Mn: 0
．． For an aluminum alloy disk containing 1% or more and the remainder consisting of AL and unavoidable impurities, after performing disk outer diameter processing and softening treatment in an appropriate order, cut a part of the disk → perform surface finishing processing in this manner. A method for manufacturing an aluminum alloy substrate for film formation and semiconductor substrate polishing support, characterized in that by applying the steps in this order, an aluminum alloy substrate with small distortion after surface finishing processing and an increase in distortion due to subsequent heat treatment of 10 μm or less is obtained. .