JP5703853B2 - Manufacturing method of bonded wafer - Google Patents

Description

  The present invention relates to a bonded wafer manufacturing method in which an ion-implanted bond wafer is bonded to a base wafer and peeled off by an ion-implanted layer.

  As the device generation progresses, in order to meet the trend target for higher performance, it is not possible to cope with only the scaling effect using conventional bulk silicon wafers, but a new device structure is required. In particular, SOI (Silicon On Insulator) wafers are attracting attention. Furthermore, because of the wide variety of devices that use SOI wafers, there is a wide range of requirements for the thickness of the buried oxide film as well as the thickness of the SOI layer.

  There are a bonding method, a SIMOX method (Separation by Implanted Oxygen method), and the like as a method for manufacturing an SOI wafer. An ion implantation separation method is known as one of the combining methods. In this method, a thermal exfoliation method (smart exfoliation method) in which a bond wafer is peeled off by an ion-implanted layer and then a thin film layer is formed by performing heat treatment at a temperature higher than 350 ° C. after performing ion implantation on a bond wafer The ion-implanted layer is weakened by heat treatment under the heat treatment conditions (for example, low-temperature heat treatment at 350 ° C. or lower) in which peeling does not occur only by heat treatment, and then stuck at room temperature. A room temperature mechanical peeling method (also called rT-CCP or SiGen method) in which a bond wafer is mechanically peeled to form a thin film layer, for example, starting from the insertion of a wedge-shaped member at the end of the bonded body near the bonding surface (Patent Document 1, Patent Document 2).

  In such a method for peeling by ion implantation, the surface roughness of the thin film layer after peeling of the bond wafer differs depending on the combination of the dose of ion implantation and the heat treatment conditions (heat treatment temperature and time). In the room temperature mechanical peeling method, when the dose amount of ion implantation is constant, the surface roughness of the thin film layer after peeling becomes better as the heat treatment temperature is lower and the time is shorter. On the other hand, if the temperature of the heat treatment is too low or the time is too short, peeling of the bond wafer itself is not realized. Therefore, from the viewpoint of improving the surface roughness of the peeled surface of the thin film layer immediately after peeling, it is ideal to select a heat treatment condition by applying a minimum heat treatment that can realize the peeling of the bond wafer.

JP 2008-300660 A JP 2008-277552 A

  However, in the conventional room temperature mechanical peeling method, it is necessary that the ion-implanted layer is weakened to some extent at the end of the bonded body into which the wedge is inserted. Instead of peeling off the wafer, peeling occurs at the bonding surface. As a result, there has been a problem that the terrace width which is an unbonded portion at the end of the bonded wafer is widened. However, as for the entire bond wafer, once the peeling starts, the peeling can be realized on the entire surface.

  On the other hand, if the bonded body is heat-treated at a sufficient temperature at which the width of the terrace does not widen at the wedge insertion part, an excessive amount of heat treatment is added inside the terrace part, so that after bonding wafer peeling There arises a problem that the surface roughness of the thin film layer is deteriorated. In this way, the minimum heat treatment amount that can avoid widening of the terrace width at the wedge insert (starting point of peeling) is different from the minimum heat treatment amount that is necessary for peeling due to external impact. However, there is a problem in that the necessary minimum heat treatment of both is not compatible. For this reason, the bonded wafers immediately after peeling by the conventional room temperature mechanical peeling method have a problem in that the width of the terrace is widened at the wedge insertion portion or the surface roughness of the peeling surface is deteriorated. It was.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is the minimum necessary to avoid the spread of the terrace width at the starting point of peeling at the same time while performing heat treatment with the minimum amount of heat treatment that can be peeled off by external impact. Manufacturing of bonded wafers that do not cause a widening of the terrace width at the part to which an external impact is applied, and can form a high-quality thin film layer with less surface roughness on the other peeling surface It aims to provide a method.

The present invention has been made in order to solve the above problems, and an ion implantation layer forming step of forming an ion implantation layer by implanting hydrogen ions or rare gas ions or both of them from a surface into a bond wafer;
A bonded body forming step of forming a bonded body by directly contacting the surface of the bond wafer with the ion-implanted surface and the surface of the base wafer through an insulating film;
A heat treatment step of weakening the ion-implanted layer by applying a heat treatment at a temperature at which peeling does not occur in the ion-implanted layer to the bonded body;
A bonding step of mechanically peeling the bond wafer with the ion-implanted layer as a boundary to form a thin film layer by applying an external impact to an end near the bonding surface of the bonded body A method of manufacturing a wafer, comprising at least:
In the heat treatment step, heat treatment is performed so that a temperature distribution is generated at the outer peripheral edge of the bonded body,
In the peeling step, the thin film layer is mechanically peeled off the bond wafer with the ion implantation layer as a boundary by applying an external impact to an end portion of the bonded body showing the highest temperature in the temperature distribution. A method for manufacturing a bonded wafer is provided.

  By such a heat treatment process, the portion where the ion implantation layer is particularly weakened at the outer peripheral edge (the highest temperature in the temperature distribution at the outer peripheral edge) while performing heat treatment with the minimum amount of heat treatment that can be peeled off by external impact. The edge of the bonded body showing the highest temperature in the temperature distribution at the outer peripheral edge). By applying external impact to the surface, there is no spread of terrace width at the part to which external impact is applied, and on the other hand, it is possible to form a good quality thin film layer with less surface roughness on the other peeled surface It becomes a manufacturing method of a wafer. Moreover, if it is the manufacturing method of the bonded wafer which can form a good-quality thin film layer with few surface roughness in this way, the reduction | decrease of the process (high temperature heat processing, grinding | polishing, etc.) which makes a peeling surface flat after that will be reduced. It becomes possible, and it becomes the manufacturing method of the bonded wafer which can also suppress deterioration of the film thickness distribution of a thin film layer.

  Further, in the heat treatment step, using a furnace in which the temperature distribution to be generated in the bonded body is known in advance, or a furnace having a mechanism for generating a temperature distribution in the bonded body, the temperature distribution at the outer peripheral edge of the bonded body. It is preferable to apply a heat treatment so that.

  The heat treatment using such a furnace makes the ion implantation layer particularly weakened at the outer peripheral edge (temperature distribution at the outer peripheral edge) while performing the heat treatment with the minimum amount of heat that can be removed by external impact. Among these, it is preferable because the end portion of the bonded body showing the highest temperature can be formed more efficiently.

  Furthermore, it is preferable to have an activation treatment step of performing plasma activation treatment on at least one of the bonded surface of the bond wafer and the bonded surface of the base wafer before the bonded body forming step.

  By performing such an activation treatment process, the bonded surface of the bond wafer or the bonded surface of the base wafer is activated by an increase in OH groups, etc., so in the subsequent bonded body forming process, hydrogen bonding is performed. This is preferable because the bond wafer and the base wafer can be bonded together more firmly.

  Moreover, in the said heat processing process, it is preferable to set and heat-process so that the temperature of a bonded body may be 200 to 350 degreeC.

  Thus, if it is 200 degreeC or more, weakening will be enough and mechanical peeling will become easy, on the other hand, if it is 350 degrees C or less, generation | occurrence | production of peeling only by heat processing can be suppressed and the surface roughness of a peeling surface will deteriorate. Since it can suppress, it is preferable.

  Further, in the heat treatment step, at the end of the bonded body showing the highest temperature in the temperature distribution at the outer peripheral edge, the temperature is 25 ° C. or more higher than the end of the bonded body showing the lowest temperature in the temperature distribution. It is preferable to heat-process so that it may become.

  If there is such a temperature difference, the ion-implanted layer is particularly weakened at the outer peripheral portion (the highest temperature distribution at the outer peripheral edge) while performing heat treatment with the minimum amount of heat that can be peeled off by external impact. The end portion of the bonded body showing the temperature can be formed more efficiently, which is preferable.

  Moreover, in the said peeling process, it is preferable to provide an external impact by inserting a wedge-shaped member in the edge part vicinity of the bonding surface of a bonding body.

  In this way, by separating the bond wafer using the wedge-shaped member, it is possible to further avoid the expansion of the terrace width in the portion to which the external impact is applied, and to form a higher quality thin film layer with less surface roughness on the other separation surface. It is preferable because it can be formed.

  As described above, according to the method for manufacturing a bonded wafer according to the present invention, a portion where the ion implantation layer has been particularly weakened (at the outer peripheral edge) while performing heat treatment with a minimum amount of heat treatment that can be peeled off by external impact. The edge of the bonded body showing the highest temperature in the temperature distribution) can be formed, and external impact is applied to the part where the weakening of the ion implantation layer is particularly advanced in the peeling process. On the other hand, it is possible to provide a method for manufacturing a bonded wafer that can form a high-quality thin film layer with less surface roughness on the other peeling surface. Moreover, if it is the manufacturing method of the bonded wafer which can form a good-quality thin film layer with few surface roughness in this way, the reduction | decrease of the process (high temperature heat processing, grinding | polishing, etc.) which makes a peeling surface flat after that will be reduced. It becomes possible, and it becomes the manufacturing method of the bonded wafer which can suppress the deterioration of the film thickness distribution of a thin film layer, and can also reduce cost.

It is a figure which shows an example of the flow of the manufacturing method of the bonded wafer of this invention. It is a schematic sectional drawing for demonstrating a peeling process. (A) It is a top view of the bonded body which shows the part which provided the external impact (wedge | feather) in Example 1 and Comparative Examples 1-2, (b) The outer periphery at the time of the heat processing in Example 1 and Comparative Examples 1-2 It is a table | surface which shows the part which provided the temperature distribution of an edge, and an external impact (wedge).

  Hereinafter, the present invention will be described in more detail, but the present invention is not limited thereto.

  As a result of intensive studies, the present inventors have conducted heat treatment so that a temperature distribution is generated at the outer peripheral edge of the bonded body, and even while performing heat treatment with a minimum heat treatment amount that can be peeled off by external impact, It has been found that the weakened portion of the implanted layer can be formed (the end portion of the bonded body showing the highest temperature in the temperature distribution at the outer peripheral edge), and the ion implanted layer is weakened in the peeling process. By applying an external impact to the part that has become particularly advanced, the terrace width does not increase in the part to which the external impact is applied, while a high-quality thin film layer with less surface roughness is formed on the other peeled surface. The present invention has been completed by finding out what can be done. Hereinafter, the present invention will be described in more detail.

In the present invention, an ion implantation layer forming step of forming an ion implantation layer by implanting hydrogen ions or rare gas ions or both of them from the surface into the bond wafer;
A bonded body forming step of forming a bonded body by directly contacting the surface of the bond wafer with the ion-implanted surface and the surface of the base wafer through an insulating film;
A heat treatment step of weakening the ion-implanted layer by applying a heat treatment at a temperature at which peeling does not occur in the ion-implanted layer to the bonded body;
A bonding step of mechanically peeling the bond wafer with the ion-implanted layer as a boundary to form a thin film layer by applying an external impact to an end near the bonding surface of the bonded body A method of manufacturing a wafer, comprising at least:
In the heat treatment step, heat treatment is performed so that a temperature distribution is generated at the outer peripheral edge of the bonded body,
In the peeling step, the thin film layer is mechanically peeled off the bond wafer with the ion implantation layer as a boundary by applying an external impact to an end portion of the bonded body showing the highest temperature in the temperature distribution. A method for manufacturing a bonded wafer is provided.

  Next, each process of the manufacturing method of the bonded wafer of this invention is demonstrated in detail with reference to FIG. 1, FIG.

[Bond wafer and base wafer]
The bond wafer 1 and the base wafer 4 used in the present invention are not particularly limited as long as they are generally used for manufacturing bonded wafers. When an SOI wafer is produced by the method of the present invention, silicon is used as a bond wafer. A single crystal wafer can be used, and a compound semiconductor wafer can also be used. Further, the bond wafer and the base wafer are preferably mirror-polished wafers (FIG. 1A).

[Thin film layer]
The thin film layer according to the present invention is formed by mechanically peeling the bond wafer with the ion-implanted layer as a boundary by applying an external impact to an end near the bonding surface of the bonded body. is there.

[Insulating film formation process]
In the bonded wafer manufacturing method of the present invention, an insulating film forming step can be performed on one or both of the bond wafer 1 and the base wafer 4, and the insulating film 2 is applied on one or both of the bond wafer 1 and the base wafer 4. Can be formed (FIG. 1B). Although it does not restrict | limit especially as the insulating film 2, When a bond wafer or a base wafer is a silicon single crystal wafer, it is preferable to form a silicon oxide film. The insulating film formed here can become an insulating layer (embedded insulating layer) 2 ′ when it becomes a bonded wafer (see FIG. 1I). Of course, the bond wafer and the base wafer can be directly bonded together without forming an insulating film.

[Ion implantation layer forming step]
The ion-implanted layer forming step according to the present invention is a step of forming the ion-implanted layer 3 by implanting hydrogen ions, rare gas ions, or both from the surface into the bond wafer 1 (see FIG. 1C). When the insulating film forming step is performed before the ion implantation layer forming step, hydrogen ions or rare gas ions or both of them are implanted into the bond wafer 1 on which the insulating film 2 is formed through the insulating film. (FIG. 1 (c)). Note that the order of the ion implantation layer forming step and the insulating film forming step is not limited thereto, and the insulating film forming step can be performed after the ion implantation layer forming step. The dose of ion implantation can be determined according to the heat treatment amount in the heat treatment step, and the depth of the ion implantation layer can be determined according to the desired thickness of the thin film layer.

[Activation process]
In the bonded wafer manufacturing method of the present invention, plasma activation treatment is performed on at least one of the ion-implanted surface of the bond wafer 1 and the bonded surface of the base wafer 4 before the bonded body forming step to activate the bonded wafer. It is possible to perform an activation treatment process for treating the surfaces 1a and 4a (FIGS. 1D and 1F). By performing such an activation treatment step, the ion-implanted surface of the bond wafer 1 and the surface to be bonded to the base wafer 4 are activated by increasing OH groups. It is preferable to perform a bonded body forming step after the activation process because the bond wafer 1 and the base wafer 4 can be bonded more firmly by hydrogen bonding or the like. For example, the plasma activation treatment can be performed with nitrogen plasma, room temperature, pressure 0.4 Torr (53.3 Pa), output 100 W, and 15 seconds.

[Laminated body forming step]
The bonded body forming process according to the present invention is a process of forming the bonded body 5 by bringing the ion-implanted surface of the bond wafer 1 and the surface of the base wafer 4 into close contact via the insulating film 2 or directly. (FIG. 1 (g)). The bonded body 5 can be formed at room temperature. Further, an automatic laminating machine can be used so that the notch positions are aligned.

[Heat treatment process]
The heat treatment step according to the present invention is a step of weakening the ion-implanted layer 3 (weakened ion-implanted layer 3 ′) by applying a heat treatment at a temperature at which peeling does not occur in the ion-implanted layer 3 to the bonded body 5. In this step, heat treatment is performed so that a temperature distribution is generated at the outer peripheral edge of the bonded body 5 (FIG. 1 (h)). As a result, the part where the ion implantation layer is particularly weakened while being heat-treated with the minimum amount of heat that can be peeled off by external impact (the end of the bonded body showing the highest temperature in the temperature distribution at the outer edge) Can be formed. As a heat treatment condition at a temperature at which separation does not occur, a critical condition in which separation is performed only by heat treatment by fixing the dose amount of ion implantation and performing heat treatment under various heat treatment conditions (temperature, time) is experimentally performed. Find it and set it in a range that does not reach the critical condition. Specifically, when the dose amount is 4 × 10 ¹⁶ to 8 × 10 ¹⁶ atoms / cm ² , the temperature can be set to 200 to 350 ° C. Thus, if it is 200 degreeC or more, weakening will be enough and mechanical peeling will become easy, on the other hand, if it is 350 degrees C or less, generation | occurrence | production of peeling only by heat processing can be suppressed and the surface roughness of a peeling surface will deteriorate. Since it can suppress, it is preferable. The heat treatment time can be 30 minutes to 4 hours. Further, in the heat treatment step, at the end portion of the bonded body showing the highest temperature in the temperature distribution at the outer peripheral edge, a temperature 25 ° C. or more higher than the end portion of the bonded body showing the lowest temperature in the temperature distribution; It is preferable to heat-process so that it may become. If there is such a temperature difference, it is possible to more efficiently form a portion where the weakening of the ion implantation layer has advanced especially in the outer peripheral portion while performing heat treatment with a minimum heat treatment amount that can be peeled off by external impact. preferable.

  In the heat treatment process, for example, a furnace in which the temperature distribution generated in the bonded body is known in advance, or a mechanism that generates a temperature distribution in the bonded body, such as a shielding plate that partially blocks heat or infrared rays from the heater. It is preferable to use a furnace having a mechanism or the like that can be installed between the heater and the bonded body so that heat treatment is performed so that a temperature distribution is generated at the outer peripheral edge of the bonded body. The temperature distribution in the furnace can be measured, for example, using a wafer in which thermocouples are installed at one central portion and eight outer peripheral portions (45-degree intervals). By performing heat treatment using such a furnace, the ion-implanted layer has become particularly weakened (within the temperature distribution at the outer edge) while performing heat treatment with the minimum amount of heat treatment that can be removed by external impact. This is preferable because the end portion of the bonded body showing the maximum temperature can be formed more efficiently. The heating means of these heat treatment furnaces may be a resistance heater or a lamp. Further, the heat treatment furnace may be a horizontal furnace, a vertical furnace, a sheet type, or a batch type. The atmospheric gas is desirably an inert gas such as argon or nitrogen, and at the same time desirably does not contain oxygen or desirably has a partial pressure of oxygen as low as possible.

[Peeling process]
In the peeling process according to the present invention, the bond wafer 1 is mechanically peeled off by using the weakened ion-implanted layer 3 ′ as a boundary by applying an external impact to the end 8 near the bonding surface of the bonded body 5. This is a step of forming the thin film layer 6, and by applying an external impact to the end portion of the bonded body 5 showing the maximum temperature in the temperature distribution, the bond wafer 1 with the weakly ion-implanted layer 3 ′ as a boundary. Are mechanically peeled to form the thin film layer 6 (FIG. 1 (i), FIG. 2). In this way, by applying an external impact to the end of the bonded body 5 that exhibits the highest temperature in the temperature distribution after the heat treatment step, the thin film layer 6 is prevented from being peeled off at the bonding surface 12, and an external impact is applied. In this way, it is possible to avoid the spread of the terrace width 13 in the portion to be processed, and the manufacturing method of the bonded wafer 7 that can have the high-quality thin film layer 6 with less surface roughness on the peeling surface 11 (FIG. 1 (i), Figure 2).

  Moreover, in the peeling process, it is preferable to apply an external impact by inserting the wedge-shaped member 9 into the end portion 8 near the bonding surface of the bonded body 5 on the peeling table 10 (FIG. 2). In this way, by peeling the bond wafer 1 using the wedge-shaped member 9, the thin film layer 6 is prevented from peeling at the bonding surface 12 more efficiently, and the terrace width 13 is widened at the portion to which an external impact is applied. This is preferable because a good quality thin film layer 6 with less surface roughness can be formed on the peeling surface 11.

  In the peeling process, the wedges are inserted into the part where the ion implantation layer of the heat-treated bonded body is particularly weakened (the end of the bonded body showing the highest temperature in the temperature distribution at the outer peripheral edge). Moreover, after aligning the direction of a bonding body, a bonding body can be mounted on the peeling stand of a peeling apparatus. In this case, when using a peeling device that has an aligner that detects the position of the notch and arranges the orientation of the bonded body before placing it on the peeling table, and has a mechanism that automatically conveys it, the orientation placed on the peeling table by the aligner By setting in advance, the position where the wedge is automatically inserted can be designated as the high temperature portion of the heat distribution.

  On the peeling table 10, the wedge-shaped member 9 of the wedge insertion mechanism can have a height matching the end portion 8 near the bonding surface of the bonded body (see FIG. 2). The wedge is inserted from the end portion of the outer peripheral portion of the wafer so that the two wafers are separated from each other with the wedge tip shape. The distance at which the wedge is inserted is set so as to maintain a sufficient distance to start peeling. However, it is ideal to select the inserted distance to a minimum so as not to cause defects in the thin film layer (for example, SOI layer) from the outer periphery to the inner side of the wafer. After the separation starts by wedge, the distance between the base wafer and the bond wafer is increased by a mechanism that separates the two wafers from each other, and the separation proceeds (for example, see Japanese Patent Application Laid-Open No. 2008-277552).

  The peeled wafer can be used as a final bonded wafer after undergoing an adjustment step including adjustment of surface modification (planarization treatment) and thin film layer thickness (for example, SOI layer thickness) by heat treatment. In addition, if it is the manufacturing method of the bonded wafer of this invention which can form a good-quality thin film layer with few surface roughness as mentioned above, the process (high temperature heat processing, grinding | polishing, etc.) which makes a peeling surface after that flat In addition, it is possible to reduce the adjustment process, and it is possible to suppress the deterioration of the film thickness distribution of the thin film layer due to these processes and to reduce the cost. At this time, the surface roughness of the thin film layer of the bonded wafer is evaluated as an important item. The surface roughness evaluation method may be direct surface measurement by AFM or indirect surface roughness measurement using the intensity of light reflection.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to the following Example.

(Example 1)
Two mirror-polished wafers made of silicon single crystal were prepared as a bond wafer and a base wafer. A 150 nm thermal oxide film was formed on the bond wafer, and hydrogen ions were implanted therein at a dose of 6.5 × 10 ¹⁶ atoms / cm ² to form an ion implanted layer.

  After cleaning the ion-implanted bond wafer and the base wafer, plasma activation treatment was performed on the bonding surfaces of both wafers to increase the bonding strength, and bonding was performed at room temperature to form a bonded body. . The plasma treatment was nitrogen plasma, room temperature, pressure 0.4 Torr (53.3 Pa), output 100 W, 15 seconds. In addition, an automatic laminating machine was used for bonding so that the notch positions were aligned.

This bonded body was subjected to heat treatment at an in-plane average temperature of 300 ° C. for 1 hour in a horizontal furnace in an N ₂ gas atmosphere. Under this heat treatment condition, peeling does not occur in the ion implanted layer, and the ion implanted layer becomes weak. At this time, the preparation direction of the bonded body was set so that the notch position was on the upper side in the furnace. In this horizontal furnace, the temperature distribution is measured in advance using a wafer with a thermocouple, and the temperature distribution during the heat treatment in which the temperature in the left-right direction in the furnace is high and the temperature in the down direction is low can be obtained. know.

  The bonded body after the heat treatment was placed on a peeling table using a peeling apparatus having an automatic transfer mechanism with an aligner. At this time, at the position inclined 45 degrees clockwise from the opposite side of the notch, the bonded body direction was selected so that the wedge was inserted, and the set value was input to the aligner (FIG. 3A). ). From the temperature distribution in the heat treatment furnace, it is known that the position inclined 45 degrees clockwise from the opposite side of the notch is the highest temperature at the outer peripheral portion (FIG. 3B). Further, in the temperature distribution in the furnace, the position where the wedges were inserted had a temperature difference of 25 ° C. with respect to the position of the lowest temperature on the outer peripheral portion, which was formed by the horizontal furnace.

  As a result of peeling at the end of the outer periphery where the temperature was highest, no expansion of the terrace width occurred at the wedge insert. Further, the wafer after peeling was combined with RTA treatment in a hydrogen atmosphere and sacrificial oxidation treatment to improve the surface roughness and adjust the film thickness of the SOI layer, and then the surface was scanned by 30 μm square with AFM. When the surface roughness was measured, a numerical value with an RMS value of 0.45 nm was obtained. The results are shown in Table 1.

(Comparative Example 1)
A bonded body was prepared and heat treated in the same manner as in Example 1. The bonded body after the heat treatment was placed on a peeling table using a peeling apparatus having an automatic transfer mechanism with an aligner. At this time, on the opposite side of the notch, the wafer orientation was selected so that the wedge was inserted, and the set value was input to the aligner (FIG. 3A). From the temperature distribution in the heat treatment furnace, it is known that the opposite side of the notch is a portion where the heat treatment temperature is low (FIG. 3B).

  As a result of peeling at the end portion showing the lowest temperature, it was found that the terrace width was expanded by about 6 mm in the wedge insertion portion as compared with other portions. The wafer after peeling was subjected to surface roughness improvement and SOI film thickness adjustment under the same conditions as in Example 1, and then the surface was scanned by 30 μm square with AFM to measure the RMS value. A numerical value of 0.45 nm was obtained. The results are shown in Table 1.

(Comparative Example 2)
A bonded body was produced and heat-treated in the same manner as in Example 1 except that the in-plane average temperature of the bonded body during the heat treatment was 325 ° C. and 1 hour. Under this heat treatment condition, peeling does not occur in the ion implanted layer, and the ion implanted layer becomes weak. The bonded body after the heat treatment was placed on a peeling table using a peeling apparatus having an automatic transfer mechanism with an aligner. At this time, on the opposite side of the notch, the wafer orientation was selected so that the wedge was inserted, and the set value was input to the aligner (FIG. 3A). From the temperature distribution in the heat treatment furnace, it is known that the opposite side of the notch is a portion where the heat treatment temperature is low (FIG. 3B).

  When peeled off at the end showing the lowest temperature, no expansion of the terrace width at the wedge insertion portion occurred. In other words, it was found that the heat treatment temperature of 325 ° C. was a temperature at which the terrace width did not expand even when the wedge was inserted in the portion where the heat treatment temperature was low. The wafer after peeling was subjected to surface roughness improvement and SOI film thickness adjustment under the same conditions as in Example 1, and then the surface was scanned with a 30 μm square by AFM and the surface roughness was measured. A numerical value of 0.55 nm was obtained. That is, in comparison with Comparative Example 1, although the terrace width did not increase, the surface roughness value increased. The results are shown in Table 1.

  As described above, in Comparative Example 1 in which heat treatment is performed at a low heat treatment average temperature and peeling is performed at the end portion showing the minimum temperature, it is shown that the terrace width is widened. It was shown that the RMS value was deteriorated in Comparative Example 2 which peeled at the part. On the other hand, according to the Example of this invention heat-processed with the low heat processing average temperature, and peel | exfoliated at the edge part which shows the maximum temperature, it was shown that a terrace width does not spread and RMS value becomes favorable.

  Thus, in the method for manufacturing a bonded wafer according to the present invention, the portion where the ion implantation layer is particularly weakened (temperature distribution of the outer peripheral edge) while performing heat treatment with a minimum amount of heat treatment that can be peeled off by external impact. End of the bonded body showing the highest temperature), and the external impact is applied to the part where the weakening of the ion implantation layer is particularly advanced in the peeling process. It has been shown that the method of manufacturing a bonded wafer can form a high-quality thin film layer with less surface roughness on the other peeled surface, while the terrace width does not increase in the portion. Moreover, if it is the manufacturing method of the bonded wafer which can form a good-quality thin film layer with few surface roughness in this way, the reduction | decrease of the process (high temperature heat processing, grinding | polishing, etc.) which makes a peeling surface flat after that will be reduced. It becomes possible, and it becomes the manufacturing method of the bonded wafer which can suppress the deterioration of the film thickness distribution of a thin film layer, and can also reduce cost.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Bond wafer, 1a ... Activation processing surface 2 ... Insulating film, 2 '... Insulating layer, 3 ... Ion implantation layer, 3' ... Fragile ion implantation layer, 4 ... Base wafer, 4a ... Activation processing surface, DESCRIPTION OF SYMBOLS 5 ... Bonded body, 6 ... Thin film layer, 7 ... Bonded wafer, 8 ... End part of bonding surface vicinity, 9 ... Wedge-shaped member, 10 ... Release table, 11 ... Release surface, 12 ... Bonding surface, 13 ... Terrace width

Claims (6)

An ion implantation layer forming step of forming an ion implantation layer by implanting hydrogen ions or rare gas ions or both of them from the surface into a bond wafer;
A bonded body forming step of forming a bonded body by directly contacting the surface of the bond wafer with the ion-implanted surface and the surface of the base wafer through an insulating film;
A heat treatment step of weakening the ion-implanted layer by applying a heat treatment at a temperature at which peeling does not occur in the ion-implanted layer to the bonded body;
A bonding step of mechanically peeling the bond wafer with the ion-implanted layer as a boundary to form a thin film layer by applying an external impact to an end near the bonding surface of the bonded body A method of manufacturing a wafer, comprising at least:
In the heat treatment step, heat treatment is performed so that a temperature distribution is generated at the outer peripheral edge of the bonded body,
In the peeling step, the thin film layer is mechanically peeled off the bond wafer with the ion implantation layer as a boundary by applying an external impact to an end portion of the bonded body showing the highest temperature in the temperature distribution. A method for producing a bonded wafer, characterized in that:   In the heat treatment step, using an oven in which the temperature distribution generated in the bonded body is known in advance, or a furnace having a mechanism for generating the temperature distribution in the bonded body, the outer peripheral edge of the bonded body The method for producing a bonded wafer according to claim 1, wherein heat treatment is performed so that the temperature distribution is generated in the wafer.   2. An activation treatment step of performing plasma activation treatment on at least one of an ion-implanted surface of the bond wafer and a bonding surface of the base wafer before the bonded body forming step. Or the manufacturing method of the bonded wafer of Claim 2.   The bonding according to any one of claims 1 to 3, wherein in the heat treatment step, the heat treatment is performed by setting the temperature of the bonded body to be 200 ° C or higher and 350 ° C or lower. Wafer manufacturing method.   In the heat treatment step, the end of the bonded body showing the highest temperature in the temperature distribution at the outer peripheral edge is 25 ° C. or more higher than the end of the bonded body showing the lowest temperature in the temperature distribution. The method for producing a bonded wafer according to any one of claims 1 to 4, wherein the heat treatment is performed so that the temperature is reached. The said peeling process WHEREIN: An external impact is provided by inserting a wedge-shaped member in the edge part of the bonding surface vicinity of the said bonding body, The Claim 1 thru | or 5 characterized by the above-mentioned. Manufacturing method for bonded wafers.

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