Laminated SOI wafers
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SUMCO CORP
- Filing Date
- 2022-10-25
- Publication Date
- 2026-08-04
Smart Images
Figure 0007899683000005 
Figure 0007899683000006 
Figure 0007899683000007
Abstract
Description
Technical Field
[0001] The present invention relates to bonded SOI wafers. Ha ni and the like.
Background Art
[0002] Conventionally, SOI (Silicon On Insulator) wafers have been used as substrates for high-frequency devices. An SOI wafer has a structure in which an oxide film layer such as silicon oxide (SiO2) and an SOI layer (for example, a single-crystal silicon) are sequentially formed on a support wafer (for example, a single-crystal silicon wafer).
[0003] One of the typical methods for manufacturing an SOI wafer is a bonding method. The bonding method is a method for manufacturing an SOI wafer by forming an oxide film layer on at least one of a support wafer and an active layer wafer, then bonding these wafers through the oxide film layer, and then performing heat treatment at a high temperature of about 1200°C.
[0004] By the way, SOI wafers have a problem that warpage is likely to occur due to the influence of the volume difference between silicon and silicon oxide (SiO2: 2.7 g / cm 3 , Si: 2.3 g / cm 3 ). In particular, when manufacturing an SOI wafer with a support-side wafer thickness of about 400 μm compared to an SOI wafer with a general support-side wafer thickness of 725 μm (in the case of φ200 mm), the influence of the oxide film layer appears remarkably on the warpage.
[0005] Patent Document 1 discloses a method for manufacturing an SOI wafer that can reduce crystal defects at the bonding interface generated during bonding heat treatment and reduce warpage occurring in the wafer by controlling the thickness difference between the thickness of the buried oxide film layer between the support wafer and the SOI layer and the thickness of the backside oxide film layer formed on the backside of the support wafer.
Prior Art Documents
[0006] [Patent Document 1] Japanese Patent Publication No. 2011-71193 [Overview of the project] [Problems that the invention aims to solve]
[0007] However, the examples disclosed in Patent Document 1 target SOI wafers with a buried oxide layer thickness of 3 μm or more and a backside oxide layer thickness of 1 μm or more. There is a problem in that it is difficult to suppress warping in SOI wafers with oxide layers of 1 μm or less.
[0008] This invention relates to a laminated SOI way that can reduce warpage while keeping the thickness of the embedded oxide layer and the back oxide layer to 1.1 μm or less. Ha The purpose is to provide. [Means for solving the problem]
[0009] The laminated SOI wafer of the present invention is a laminated SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, wherein the thickness of the support wafer is 400 ± 10 μm, the thickness of the SOI layer is 30 ± 1 μm, the thickness of the embedded oxide film layer and the backside oxide film layer formed on the side of the support wafer opposite to the embedded oxide film layer are each 1.1 μm or less, and the difference in oxide film thickness obtained by subtracting the thickness of the embedded oxide film layer from the thickness of the backside oxide film layer is -0.3 μm or more and 1.0 μm or less.
[0010] The laminated SOI wafer of the present invention is a laminated SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, wherein the thickness of the support wafer is 400 ± 10 μm, the thickness of the SOI layer is 70 ± 1 μm, the thickness of the embedded oxide film layer and the backside oxide film layer formed on the side of the support wafer opposite to the embedded oxide film layer are each 1.1 μm or less, and the difference in oxide film thickness obtained by subtracting the thickness of the embedded oxide film layer from the thickness of the backside oxide film layer is -0.3 μm or more and 1.0 μm or less.
[0011] The laminated SOI wafer of the present invention is a laminated SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, wherein the thickness of the support wafer, on the side opposite to the embedded oxide film layer where no oxide film layer is formed, is 400 ± 10 μm. The SOI layer has a thickness of 30 ± 1 μm, and the embedded oxide film layer has a thickness greater than 0 μm and is 0.3 μm or less.
[0012] The laminated SOI wafer of the present invention is a laminated SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, wherein the thickness of the support wafer, on the side opposite to the embedded oxide film layer where no oxide film layer is formed, is 400 ± 10 μm. The SOI layer has a thickness of 70 ± 1 μm, and the embedded oxide film layer has a thickness greater than 0 μm and less than or equal to 0.3 μm.
[0013] The present invention relates to a method for manufacturing a bonded SOI wafer, wherein an SOI layer is formed on a support wafer via an embedded oxide layer, and a backside oxide layer is formed on the side of the support wafer opposite to the embedded oxide layer, and the method comprises: a correlation formula calculation step of calculating a correlation formula consisting of a linear function between the oxide film thickness difference obtained by subtracting the thickness of the embedded oxide layer from the thickness of the backside oxide layer and the amount of warpage of the bonded SOI wafer; a warpage amount setting step of setting an allowable range for the amount of warpage; a thickness difference setting step of setting an allowable range for the oxide film thickness difference based on the correlation formula and the allowable range for the amount of warpage; and an oxide film layer thickness setting step of setting the thickness of the embedded oxide layer and the backside oxide layer to a range of 1.1 μm or less based on the allowable range for the oxide film thickness difference. [Brief explanation of the drawing]
[0014] [Figure 1] This is a cross-sectional view of a bonded SOI wafer according to one embodiment of the present invention. [Figure 2] This is a manufacturing process diagram illustrating the manufacturing process for a bonded SOI wafer in which an oxide film layer is formed on the wafer side for the active layer. [Figure 3] This is a manufacturing process diagram illustrating the manufacturing process for a bonded SOI wafer in which an oxide film layer is formed on the support wafer side. [Figure 4] This is a flowchart illustrating a method for manufacturing a bonded SOI wafer according to the fifth embodiment of the present invention. [Figure 5] This graph shows the relationship between the difference in oxide film thickness and the amount of warpage of the bonded SOI wafers. [Modes for carrying out the invention]
[0015] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The laminated SOI wafer of the present invention is a wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer. The inventors of the present invention have conducted sincere research on the phenomenon of warpage occurring due to the volume difference between the support wafer of the bonded SOI wafer and the oxide film layer. As a result, it was found that there is a correlation between the thickness difference obtained by subtracting the thickness of the buried oxide film layer (BOX (Buried Oxide) layer) from the thickness of the back oxide film layer (ROX (Rear Oxide) layer) (hereinafter, sometimes simply referred to as the oxide film thickness difference), and the warpage amount of the bonded SOI wafer. It was considered that the warpage of the bonded SOI wafer can be suppressed by controlling this oxide film thickness difference.
[0016] 〔First Embodiment〕 As shown in FIG. 1, the bonded SOI wafer 10 is a bonded wafer in which an SOI layer 15 is formed on a support wafer 12 via a buried oxide film layer 16. A back oxide film layer 17 is formed on the side of the support wafer 12 opposite to the buried oxide film layer 16.
[0017] The support wafer 12 is preferably a silicon single crystal wafer with mirror finish. The SOI layer 15 is an active layer formed of a silicon single crystal. The oxide film layers 16 and 17 can be formed, for example, by thermal oxidation or CVD.
[0018] The bonded SOI wafer 10 of the first embodiment is characterized in that the thickness of the support wafer 12 is 400 ± 10 μm, the thickness of the SOI layer 15 is 30 ± 1 μm, the thicknesses of the buried oxide film layer 16 and the back oxide film layer 17 are each 1.1 μm or less, and the oxide film thickness difference is -0.3 μm or more and 1.0 μm or less. The oxide film thickness difference is the value obtained by subtracting the thickness of the buried oxide film layer 16 from the thickness of the back oxide film layer 17. For example, when the thickness of the buried oxide film layer 16 is 0.3 μm and the thickness of the back oxide film layer 17 is 0.1 μm, the oxide film thickness difference is -0.2 μm.
[0019] 〔Second Embodiment〕 The bonded SOI wafer 10A of the second embodiment (see Figures 2 and 3) is characterized in that the thickness of the support wafer 12 is 400 ± 10 μm, the thickness of the SOI layer 15 is 70 ± 1 μm, the thickness of the embedded oxide film layer 16 and the backside oxide film layer 17 are 1.1 μm or less, and the difference in oxide film thickness obtained by subtracting the thickness of the embedded oxide film layer 16 from the thickness of the backside oxide film layer 17 is -0.3 μm or more and 1.0 μm or less. In other words, the bonded SOI wafer 10 of the first embodiment and the bonded SOI wafer 10A of the second embodiment differ in the thickness of the SOI layer 15.
[0020] [Third Embodiment] In the third embodiment, no oxide layer is formed on the side of the support wafer 12 opposite to the embedded oxide layer 16 of the bonded SOI wafer 10D (see Figures 2 and 3). The bonded SOI wafer 10D of the third embodiment is characterized in that the thickness of the support wafer 12 is 400 ± 10 μm, the thickness of the SOI layer 15 is 30 ± 1 μm, and the thickness of the embedded oxide film layer 16 is greater than 0 μm and 0.3 μm or less.
[0021] [Fourth Embodiment] In the fourth embodiment, no oxide layer is formed on the side of the support wafer 12 opposite to the embedded oxide layer 16 of the bonded SOI wafer 10C (see Figures 2 and 3). The bonded SOI wafer 10C of the fourth embodiment is characterized in that the thickness of the support wafer 12 is 400 ± 10 μm, the thickness of the SOI layer 15 is 70 ± 1 μm, and the thickness of the embedded oxide film layer 16 is greater than 0 μm and 0.3 μm or less. In other words, the laminated SOI wafer 10D of the third embodiment and the laminated SOI wafer 10C of the fourth embodiment differ in the thickness of the SOI layer 15.
[0022] According to the bonded SOI wafer 10 of each of the above embodiments, the amount of warping of the bonded SOI wafer 10 can be reduced by controlling the thickness of the oxide film layers 16 and 17. Specifically, when the thickness of the SOI layer 15 is 30 ± 1 μm, the amount of warpage can be reduced to 130 μm or less, and when the thickness of the SOI layer 15 is 70 ± 1 μm, the amount of warpage can be reduced to 180 μm or less.
[0023] Next, we will describe the manufacturing method for the bonded SOI wafer 10. The bonded SOI wafer 10 is formed by bonding an active layer wafer 11 and a support wafer 12 with an embedded oxide film layer 16 in between. There are two methods for forming the oxide film layer 11a (see Figure 2) on the active layer wafer 11 side before bonding, and a method for forming the oxide film layer 12a (see Figure 3) on the support wafer 12 side before bonding. First, we will explain a method in which an oxide film layer 11a is formed on the active layer wafer 11 before bonding.
[0024] [Manufacturing process for laminated SOI wafers, where an oxide film layer is formed on the wafer side for the active layer] Figure 2 is a manufacturing process diagram showing the manufacturing process of a bonded SOI wafer 10. First, as shown in Figure 2, an active layer wafer 11 and a support wafer 12 for supporting the active layer wafer 11 are prepared. Both the active layer wafer 11 and the support wafer 12 are preferably mirror-finished wafers with a diameter of 200 mm. The thickness of the support wafer 12 is 400 ± 10 μm.
[0025] Next, the active layer wafer 11 and the support wafer 12 are subjected to SC-1 cleaning, pure water rinsing, and hydrofluoric acid organic acid cleaning in that order to clean the surface of each wafer.
[0026] Next, an oxide film layer 11a is formed over the entire surface of the active layer wafer 11. The oxide film layer 11a later becomes a buried oxide film layer 16. The oxide film layer 11a can be formed by, for example, thermal oxidation or CVD. The thickness of the oxide film layer 11a formed on the active layer wafer 11 is adjusted according to the thickness of the buried oxide film layer 16 of the final bonded SOI wafer 10.
[0027] Next, the active layer wafer 11 and the support wafer 12 are subjected to SC-1 cleaning, pure water rinsing, and hydrofluoric acid organic acid cleaning in that order to hydrogen-terminate the surface of each wafer. After that, the two wafers 11 and 12 with hydrogen-terminated surfaces are stacked on top of each other, and pressure is applied by placing a weight on top to bond the two wafers 11 and 12 via the oxide film layer 11a, thereby forming a superimposed wafer 13.
[0028] Next, a bonding annealing heat treatment is performed. The bonding annealing heat treatment includes the steps of heating the stacked wafers 13 in an annealing furnace for a certain period of time and gradually lowering the temperature inside the heated furnace to room temperature. In the bonding annealing heat treatment, heating the stacked wafers 13 for a certain period of time can increase the adhesive strength of the bonding interface. Then, by gradually lowering the temperature inside the heated furnace to room temperature, residual stress inside the wafer can be removed. In addition, by performing the bonding annealing heat treatment, an oxide film layer 14 is formed on the stacked wafers 13. The oxide film layer 14 includes an oxide film layer 14A formed on the support wafer 12 side and an oxide film layer 14B formed on the active layer wafer 11 side. In this process, the thickness of the oxide film layer 14A formed on the support wafer 12 can be controlled by the processing time. This oxide film layer 14A later becomes the backside oxide film layer 17. The oxide film layer 14B formed on the active layer wafer 11 side is formed on top of the oxide film layer 11a initially formed on the active layer wafer 11.
[0029] Next, the active layer wafer 11 side of the heat-treated stacked wafer 13 is subjected to a thinning treatment so that the SOI layer 15 has a thickness of 70 ± 1 μm. The thinning treatment is performed by surface grinding and mirror polishing. As a result, an SOI layer 15 is formed on the support wafer 12 via an embedded oxide layer 16, and a backside oxide layer 17 is formed on the back surface of the support wafer 12, resulting in a bonded SOI wafer 10A (first bonded SOI wafer 10A) with an SOI layer thickness of 70 μm.
[0030] By performing a thinning treatment on the SOI layer 15 of the first bonded SOI wafer 10A, a backside oxide film layer 17 is formed, and a bonded SOI wafer 10B (second bonded SOI wafer 10B) with an SOI layer thickness of 30±1 μm is obtained. Furthermore, by performing a removal process of the backside oxide film layer 17 on the first bonded SOI wafer 10A, a fourth bonded SOI wafer 10C can be manufactured without the backside oxide film layer 17 and with an SOI layer thickness of 70±1μm. Furthermore, by removing the backside oxide film layer 17 from the fourth bonded SOI wafer 10C, or by performing a thickness reduction treatment on the second bonded SOI wafer 10B, a third bonded SOI wafer 10D can be manufactured without the backside oxide film layer 17 and with an SOI layer thickness of 30±1μm.
[0031] [Manufacturing process for bonded SOI wafers, where an oxide film layer is formed on the support wafer side] Next, a method for forming an oxide film layer 12a on the support wafer 12 side before bonding will be described.
[0032] The manufacturing process for a bonded SOI wafer in which an oxide film layer 12a is formed on the support wafer 12 side is basically the same as the manufacturing process for a bonded SOI wafer in which an oxide film layer is formed on the active layer wafer side, so only the differences will be explained. As shown in Figure 3, an oxide film layer 12a is formed on the entire surface of the support wafer 12. The oxide film layer 12a later becomes the back surface oxide film layer 17 together with the oxide film layer 14A. That is, in the manufacturing process of a bonded SOI wafer in which the oxide film layer is formed on the support wafer side, the back surface oxide film layer 17 is formed from the oxide film layer 12a and the oxide film layer 14A formed by annealing heat treatment. The thickness of the oxide film layer 12a and the thickness of the oxide film layer 14A formed by the annealing heat treatment are adjusted according to the final thickness of the back surface oxide film layer 17 of the SOI wafer 10.
[0033] Next, similar to the manufacturing process for laminated SOI wafers in which an oxide film layer is formed on the wafer side for the active layer, two wafers 11 and 12 are bonded together via an oxide film layer 12a to form a superimposed wafer 13, and an oxide film layer 14 is formed on the superimposed wafer 13 by bonding annealing heat treatment.
[0034] Next, the wafer 11 side of the overlapping wafer 13 is subjected to a thinning process to obtain the first bonded SOI wafer 10A. The second bonded SOI wafer 10B, the third bonded SOI wafer 10D, and the fourth bonded SOI wafer 10C can also be obtained in the same manner as the manufacturing process for bonded SOI wafers in which an oxide film layer is formed on the wafer side of the active layer.
[0035] The above describes the manufacturing process for a bonded SOI wafer in which an oxide film layer is formed on the active layer wafer side, and the manufacturing process for a bonded SOI wafer in which an oxide film layer is formed on the support wafer side. However, a bonded SOI wafer may also be manufactured by forming oxide film layers on both the active layer wafer and the support wafer, and then bonding the active layer wafer and the support wafer together.
[0036] [Fifth Embodiment] Next, as a fifth embodiment, a method for manufacturing a laminated SOI wafer will be described, which involves calculating a correlation formula based on the correlation between the difference in oxide film thickness and the amount of warpage of the laminated SOI wafer. As shown in Figure 4, the manufacturing method for a bonded SOI wafer according to the fifth embodiment includes a first bonded SOI wafer manufacturing step S1, a correlation formula calculation step S2, a warpage amount setting step S3, a thickness difference setting step S4, an oxide film layer thickness setting step S5, and a second bonded SOI wafer manufacturing step S6.
[0037] The first bonded SOI wafer manufacturing process S1 is a process for manufacturing a bonded SOI wafer that will serve as a sample for calculating the correlation formula described later. In the first bonded SOI wafer manufacturing process S1, multiple bonded SOI wafers 10 are manufactured while changing the thickness of the embedded oxide layer 16 and the back oxide layer 17. In this embodiment, the thickness of the embedded oxide layer 16 is changed to 0.3 μm, 1.0 μm, 2.0 μm, etc., and the thickness of the back oxide layer 17 is changed to 0 μm (back oxide layer: none), 0.3 μm, 1.0 μm, 1.04 μm, 1.3 μm, 2.23 μm, etc.
[0038] The correlation formula calculation step S2 is a step in which a correlation formula is calculated that represents the correlation between the difference in oxide film thickness and the amount of warpage of the bonded SOI wafers, using multiple bonded SOI wafers with different thicknesses of oxide film layers 16 and 17 manufactured in the first bonded SOI wafer manufacturing step S1. In the correlation formula calculation step S2, first, the amount of warpage of the manufactured bonded SOI wafer 10 is measured. The amount of warpage can be measured using a flatness measuring device. In this embodiment, the amount of warpage is defined as the WARP value shown by the flatness measuring device with the BOW value plus or minus sign added, but the definition of the amount of warpage may be changed as appropriate.
[0039] Next, the difference in oxide film thickness and the amount of warpage are input into a computer and plotted on a graph to obtain a graph like the one shown in Figure 5. In the graph shown in Figure 5, the horizontal axis represents the difference in oxide film thickness (μm), and the vertical axis represents the amount of warpage (μm).
[0040] Next, the input data and graphs are subjected to regression analysis to calculate correlation equations for both the case where the SOI layer 15 has a thickness of 30 μm and the case where it has a thickness of 70 μm. If x is the difference in oxide film thickness and y is the amount of warpage, then when the thickness of the SOI layer 15 is 30 μm, the correlation between the amount of warpage and the difference in oxide film thickness will be a linear function such as equation (1). y = - 176.1 × x + 25.9 ··· (1) The straight line in equation (1) is shown in Figure 5 with the sign L1.
[0041] Similarly, when the thickness of the SOI layer 15 is 70 μm, the correlation between the amount of warpage and the difference in oxide film thickness becomes a linear function, for example, as shown in equation (2). y = - 174.1 × x + 64.5 ··· (2) The straight line in equation (2) is shown in Figure 5 with the sign L2.
[0042] The warpage amount setting step S3 is a step in which the allowable range of warpage of the bonded SOI wafer 10 is set. The allowable range of warpage of the bonded SOI wafer 10 can be set as appropriate according to the specifications, but for example it can be set to -100 μm or more and +100 μm or less.
[0043] The thickness difference setting step S4 is a step in which the allowable range of the oxide film thickness difference is set based on the correlation formula calculated in the correlation formula calculation step S2 and the allowable range of the warpage amount set in the warpage amount setting step S3. When the allowable range of the warpage amount is set to -100 μm or more and +100 μm or less, the allowable range of the oxide film thickness difference can be set from the correlation formula and graph to -0.42 μm or more and 0.71 μm or less when the thickness of the SOI layer 15 is 30 μm, and to -0.20 μm or more and 0.94 μm or less when the thickness of the SOI layer 15 is 70 μm. Furthermore, it is preferable to narrow the allowable range of oxide film thickness difference, taking into account variations in the manufacturing process. For example, the allowable range of oxide film thickness difference can be -0.31 μm or more and 0.60 μm or less when the thickness of the SOI layer 15 is 30 μm, and -0.09 μm or more and 0.83 μm or less when the thickness of the SOI layer 15 is 70 μm.
[0044] The oxide film layer thickness setting step S5 is a step in which the thicknesses of the oxide film layers 16 and 17 are set to a range of 1 μm or less, based on the allowable range of the oxide film thickness difference set in the thickness difference setting step S4. For example, if the thickness of the SOI layer 15 is 30 μm, the operator can set the thickness of the embedded oxide film layer 16 to 0.3 μm and the thickness of the back surface oxide film layer 17 to 0.1 μm (oxide film thickness difference: -0.2 μm).
[0045] The second bonded SOI wafer manufacturing process S6 is a process for manufacturing an SOI wafer based on the thickness of the oxide film layer set in the oxide film layer thickness setting process S5. In other words, in the second bonded SOI wafer manufacturing process S6, a bonded SOI wafer 10 as a product is manufactured based on the set thicknesses of the oxide film layers 16 and 17.
[0046] In this embodiment, the correlation formula was calculated by manufacturing multiple bonded SOI wafers and measuring the warpage of these multiple bonded SOI wafers, but this is not the only method. For example, the correlation formula could be calculated by measuring the warpage of multiple bonded SOI wafers that have already been manufactured.
[0047] In the above embodiment, a correlation equation consisting of a linear function between the difference in oxide film thickness and the amount of warpage of the bonded SOI wafer was calculated. Based on this correlation equation and the allowable range of the amount of warpage, an allowable range for the difference in oxide film thickness was set, and a bonded SOI wafer was manufactured with an oxide film layer thickness corresponding to this allowable range for the difference in oxide film thickness. As a result, it is possible to manufacture a bonded SOI wafer with suppressed warpage while keeping the oxide film layer thickness to, for example, 1.1 μm or less. [Examples]
[0048] Next, the present invention will be described in more detail with reference to examples and comparative examples. [SOI layer thickness 30 μm] For a bonded SOI wafer with an SOI layer thickness of 30 μm, we determined the oxide film thickness difference that satisfies the acceptable range of warpage. First, as shown in Table 1, we manufactured several bonded SOI wafers with different thicknesses for the embedded oxide layer (BOX) and the back oxide layer (ROX).
[0049] [Table 1]
[0050] In Table 1, "BOX Oxidized Surface" refers to the wafer on which the oxide film layer is formed, among the active layer wafer and the support wafer. "Active Side" indicates that the oxide film layer is formed on the active layer wafer, and "Support Side" indicates that the oxide film layer is formed on the support wafer. Next, the amount of warpage of several bonded SOI wafers that had been manufactured was measured.
[0051] The results shown in Table 1 indicate that by setting the oxide film thickness difference between -0.3 μm and 1.0 μm, it is possible to achieve an oxide film thickness of 1.1 μm while maintaining a warpage of -130 μm and +130 μm (Examples 1-8). Furthermore, under the condition that the difference in oxide film thickness is -0.3 μm or more and 1.0 μm or less, if the thickness of the back oxide film layer 17 is 0 μm (none) (Examples 1, 3, 5, 7), the thickness of the embedded oxide film layer 16 is greater than 0 μm and 0.3 μm or less.
[0052] [SOI layer thickness 70 μm] For a bonded SOI wafer with an SOI layer thickness of 70 μm, we determined the oxide film thickness difference that satisfies the allowable range of warpage. First, as shown in Table 2, multiple laminated SOI wafers with different thicknesses for the embedded oxide layer and the backside oxide layer were manufactured, and then the warpage of the multiple laminated SOI wafers was measured.
[0053] [Table 2]
[0054] The results shown in Table 2 indicate that by setting the oxide film thickness difference between -0.3 μm and 1.0 μm, the warpage can be set between -180 μm and +180 μm (Examples 9-16). Furthermore, under the condition that the difference in oxide film thickness is -0.3 μm or more and 1.0 μm or less, if the thickness of the back oxide film layer 17 is 0 μm (none) (Examples 9, 11, 13, 15), the thickness of the embedded oxide film layer 16 is greater than 0 μm and 0.3 μm or less.
[0055] [SOI layer thickness is 30 μm, and the thickness of the support wafer is varied.] The same verification was performed as with a 30 μm SOI layer thickness by varying the thickness of the support wafer. As shown in Table 3, bonded SOI wafers were manufactured with support wafer thicknesses of 390 μm, 400 μm, and 410 μm.
[0056] [Table 3]
[0057] As shown in Table 3, even when the thickness of the support wafer is 390 μm or 410 μm, the amount of warping is roughly the same or smaller. Therefore, even in the range of a support wafer thickness of 400 ± 10 μm, the condition of having an oxide film thickness difference of -0.3 μm or more and 1.0 μm or less applies.
[0058] [SOI layer thickness is 70 μm, and the thickness of the support wafer is varied.] The same verification was performed as with a 70 μm SOI layer thickness by varying the thickness of the support wafer. As shown in Table 4, bonded SOI wafers were manufactured by varying the thickness of the support wafer to 390 μm, 400 μm, and 410 μm.
[0059] [Table 4]
[0060] As shown in Table 4, even when the thickness of the support wafer is 390 μm or 410 μm, the amount of warpage is roughly the same or smaller. Therefore, even in the range of a support wafer thickness of 400 ± 10 μm, the condition of having an oxide film thickness difference of -0.3 μm or more and 1.0 μm or less applies. [Explanation of Symbols]
[0061] 10...Laminated SOI wafer, 11...Wafer for active layer, 11a...Oxide film layer, 12...Support wafer, 12a...Oxide film layer, 13...Overlay wafer, 14...Oxide film layer, 15...SOI layer, 16...Embedded oxide film layer, 17...Backside oxide film layer, S1...First laminated SOI wafer manufacturing process, S2...Correlation formula calculation process, S3...Quantity setting process, S4...Thickness difference setting process, S5...Oxide film layer thickness setting process, S6...Second laminated SOI wafer manufacturing process.
Claims
1. In a bonded SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, The diameter of the aforementioned support wafer is 200 mm. The thickness of the support wafer is 400 ± 10 μm. The thickness of the SOI layer is 30 ± 1 μm. The thickness of the embedded oxide film layer and the backside oxide film layer formed on the side of the support wafer opposite to the embedded oxide film layer are each 1.1 μm or less. The difference in oxide film thickness obtained by subtracting the thickness of the embedded oxide film layer from the thickness of the back surface oxide film layer is -0.3 μm or more and 1.0 μm or less. A laminated SOI wafer with a warp of 130 μm or less.
2. In a bonded SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, The diameter of the aforementioned support wafer is 200 mm. The thickness of the support wafer is 400 ± 10 μm. The thickness of the SOI layer is 70 ± 1 μm. The thickness of the embedded oxide film layer and the backside oxide film layer formed on the side of the support wafer opposite to the embedded oxide film layer are each 1.1 μm or less. The difference in oxide film thickness obtained by subtracting the thickness of the embedded oxide film layer from the thickness of the back surface oxide film layer is -0.3 μm or more and 1.0 μm or less. A laminated SOI wafer with a warp of 180 μm or less.
3. In a bonded SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, The diameter of the support wafer, on the side opposite to the embedded oxide layer, is 200 mm, and the thickness of the support wafer is 400 ± 10 μm. The thickness of the SOI layer is 30 ± 1 μm. The thickness of the embedded oxide film layer is greater than 0 μm and 0.3 μm or less. A laminated SOI wafer with a warp of 130 μm or less.
4. In a bonded SOI wafer in which an SOI layer is formed on a support wafer via an embedded oxide film layer, The diameter of the support wafer, on the side opposite to the embedded oxide layer, is 200 mm, and the thickness of the support wafer is 400 ± 10 μm. The thickness of the SOI layer is 70 ± 1 μm. The thickness of the embedded oxide film layer is greater than 0 μm and 0.3 μm or less. A laminated SOI wafer with a warp of 180 μm or less.