JP2013131611A - Semiconductor device manufacturing method and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method and a semiconductor device, which can prevent cracks of a wafer in manufacturing processes.SOLUTION: A semiconductor device manufacturing method of a present embodiment comprises: a step (S11) of preparing a laminate having a structure in which two wafers are soldered and laminated via an impurity supply source layer, and the two wafers are welded via the impurity supply source layer; a step (S12) of performing a processing treatment on each principal surface of the two wafers composing the laminate; and a step (S13) of detaching the two wafers which have been subjected to the processing treatment.

Description

  The present invention relates to a semiconductor device manufacturing method and a semiconductor device manufactured using the manufacturing method.

  A mesa diode element is known as a semiconductor device having a mesa structure. Conventionally, when manufacturing this type of semiconductor device, a plurality of wafers are stacked with an impurity supply source layer in between, and the stacked wafers are baked to thermally diffuse impurities into each wafer. Then, after the impurities are diffused, the wafer is separated into wafers one by one and the next process is performed (see Patent Document 1).

With reference to FIG. 9 and FIG. 10, the manufacturing process of the mesa diode element will be described.
As shown in step (A) of FIG. 9, a plurality of wafers W are stacked by alternately sandwiching an impurity supply source layer 1 containing a donor such as phosphorus and an impurity supply source layer 2 containing an acceptor such as boron. . By baking in a state where a plurality of wafers W are stacked in this manner, the impurities contained in the impurity supply source layer 1 and the impurity supply source layer 2 are diffused into each wafer W. Thereby, as shown in step (B) of FIG. 9 described later, an n-type diffusion layer 11 in which donors from the impurity supply source layer 1 are diffused is formed on one surface side of each wafer, and on the other surface side. The p-type diffusion layer 21 in which the acceptor from the impurity supply source layer 2 is diffused is formed. In addition, each wafer W is welded through the impurity supply source layer 1 or the impurity supply source layer 2 by firing at this time.

  Subsequently, the plurality of stacked wafers W are separated by a fusion layer formed by the impurity supply source layer 1, thereby melting the wafer W via the impurity supply source layer 2 as shown in step (B) of FIG. 9. Two attached wafers W are obtained. Note that, in the step (B) of FIG. 9, for example, two wafers welded with the impurity supply source layer 2 interposed therebetween are shown, but a plurality of such wafer sets are obtained.

  Subsequently, as shown in step (C) of FIG. 9, the fusion layer formed by the impurity supply source layer 1 and the fusion layer formed by the impurity supply source layer 2 are removed by hydrofluoric acid treatment. Thus, one wafer W is obtained in which the n-type diffusion layer 11 is formed on one surface and the p-type diffusion layer 21 is formed on the other surface.

  Subsequently, as shown in step (D) of FIG. 9, oxide films 3 are formed on both surfaces of one wafer W. Then, as shown in step (E) of FIG. 10, a photoresist 4 is applied on the oxide film 3, and a mesa groove pattern is exposed on the photoresist 4. Oxide film etching is performed using the photoresist 4 on which the mesa groove pattern is formed as a mask, thereby forming a mesa groove pattern in the oxide film 3. Then, as shown in step (F) of FIG. 9, the back surface resist protective layer 5 is formed on the back surface of the wafer W.

  Subsequently, as shown in step (G) of FIG. 10, the mesa groove 6 is formed on the main surface of the wafer W by etching or the like using the oxide film 3 and the photoresist 4 on which the mesa groove pattern is formed as a mask. Then, as shown in step (H) of FIG. 10, after removing the photoresist 4, a passivation 7 is formed so as to cover the mesa groove 6. Then, as shown in step (I) in FIG. 10, the oxide film 3 is removed, and electrodes 8 are formed on both surfaces of the wafer W as shown in step (J) in FIG. Finally, as shown in FIG. 10K, the wafer W is divided into a plurality of chips along the mesa groove 6 to obtain a mesa diode element.

JP 2009-194011 A

  By the way, in recent years, the wafer is easily cracked in the manufacturing process due to the thinning and large diameter of the wafer. According to the method for manufacturing the mesa diode element described above, the mechanical strength in the mesa groove 6 is lowered, so that there is a problem that the wafer is easily cracked.

  The present invention has been made in view of the above circumstances, and provides a semiconductor device manufacturing method and a semiconductor device capable of suppressing cracking of a wafer in each manufacturing process without causing an increase in the number of manufacturing processes. For the purpose.

  In order to solve the above-described problem, a method of manufacturing a semiconductor device according to the present invention is a stacked body in which two wafers are stacked with an impurity supply source layer interposed therebetween, and the 2 A step of preparing a laminated body having a structure in which a plurality of wafers are welded, a step of processing each main surface of the two wafers forming the laminated body, and the step of performing the processing A method of manufacturing a semiconductor device including a step of peeling two wafers.

  In the method for manufacturing a semiconductor device, for example, the step of processing each main surface of the two wafers may be performed by using the oxide film on which the pattern for the mesa groove is formed as a mask. Forming a mesa groove on the main surface; and forming a passivation covering the mesa groove.

In the method for manufacturing a semiconductor device, for example, the step of peeling the two wafers includes a step of removing the oxide film together with a fusion layer formed by the impurity source layer.
In the method for manufacturing a semiconductor device, for example, after the step of peeling the two wafers, a step of forming electrodes on both surfaces of the peeled wafers, and the wafers with the electrodes formed on the mesa grooves And dividing the chip into a plurality of chips.

  In the manufacturing method of the semiconductor device, for example, the step of preparing the stacked body includes the step of forming an oxide film on both surfaces of the plurality of wafers including the two wafers, and the step of forming the oxide film from one side of the plurality of wafers. Removing the oxide film, laminating the plurality of wafers with the impurity source layer sandwiched between the surfaces from which the oxide film has been removed, and firing the laminated wafers to form the impurities Welding the two wafers sandwiching the supply source layer and diffusing impurities contained in the impurity supply source layer into the plurality of wafers; and bonding the plurality of wafers on the surface on which the oxide film is disposed. Separating to obtain the laminate.

  In the method for manufacturing a semiconductor device, for example, the step of preparing the stacked body includes a first impurity supply source layer and a second impurity supply as the impurity supply source layer between a plurality of wafers including the two wafers. By laminating the plurality of wafers with the source layers alternately sandwiched, and firing the plurality of laminated wafers, the two wafers sandwiching the second impurity supply source layer are fused and the Diffusing each impurity contained in the first and second impurity source layers into a plurality of wafers; separating the plurality of wafers on a surface where the first impurity source layers are located; A step of obtaining two wafers sandwiched between the impurity supply source layers, and removing the weld layer formed by the first impurity supply source layer from the two welded wafers to obtain the laminate. Process

  The semiconductor device according to the present invention has the configuration of the semiconductor device manufactured by any of the above manufacturing methods.

  ADVANTAGE OF THE INVENTION According to this invention, the mechanical strength of the wafer in the manufacturing process of a semiconductor device can be improved. Therefore, it becomes possible to prevent the wafer from being cracked in each manufacturing process.

It is a flowchart for demonstrating the manufacturing method of the semiconductor device by 1st Embodiment of this invention. It is sectional drawing of the semiconductor device for demonstrating process (A)-(D) in the manufacturing method of the semiconductor device by 1st Embodiment of this invention. It is sectional drawing of the semiconductor device for demonstrating process (E)-(G) in the manufacturing method of the semiconductor device by 1st Embodiment of this invention. It is sectional drawing of the semiconductor device for demonstrating process (H)-(J) in the manufacturing method of the semiconductor device by 1st Embodiment of this invention. It is a flowchart for demonstrating the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is sectional drawing of the semiconductor device for demonstrating process (A)-(C) in the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is sectional drawing of the semiconductor device for demonstrating process (D)-(G) in the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is sectional drawing of the semiconductor device for demonstrating process (H)-(J) in the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is sectional drawing of the semiconductor device for demonstrating process (A)-(D) in the manufacturing method of the mesa type diode element by a prior art. It is sectional drawing of the semiconductor device for demonstrating process (E)-(K) in the manufacturing method of the mesa type diode element by a prior art.

  Hereinafter, embodiments of a method for manufacturing a semiconductor device according to the present invention will be described with reference to the drawings, taking a mesa diode element as an example.

(First embodiment)
The semiconductor device manufacturing method according to the first embodiment of the present invention will be described along the flow shown in FIG. 1 with reference to the process diagrams shown in FIGS.

The method for manufacturing a semiconductor device according to the first embodiment is a method for manufacturing a mesa diode element having a device structure in which an impurity diffusion layer is formed on one surface of a chip.
In FIG. 1, steps S11A, S11B, S11C, and S11D show detailed steps of step S11, and steps S12A, S12B, and S12C show detailed steps of step S12.
In the first embodiment, the structure in which the impurity diffusion layer is formed only on one surface (one surface) of the chip is taken as an example. However, the present invention is not limited to this example, and the diffusion layer is also formed on the other surface of the chip. You may do it. If the diffusion layers are formed on one surface and the other surface of the chip as described above, the depths of the diffusion layers of the p-type impurity and the n-type impurity can be arbitrarily set.

  First, a stacked body in which two wafers are stacked with an impurity supply source layer interposed therebetween is prepared (step S11).

  More specifically, a plurality of n-type wafers W including two wafers forming this laminated body are prepared, and, as shown in step (A) of FIG. 2, on both surfaces of each wafer W to be a laminated body. An oxide film 110 is formed (step S11A). The oxide film 110 is formed, for example, by heat-treating the wafer under predetermined conditions. Then, as shown in step (B) of FIG. 2, the oxide film 110 is removed from one side of each wafer W (step S11B).

  Subsequently, as shown in step (C) of FIG. 2, a plurality of wafers W are stacked so that the impurity supply source layer 120 is sandwiched between the surfaces from which the oxide film 110 has been removed. In the present embodiment, the impurity supply source layer 120 includes an acceptor such as boron as an impurity. When attention is paid to the boundary between two adjacent wafers W among the plurality of stacked wafers W, there are a surface where the impurity supply source layer 120 exists and a surface where the oxide films 110 are in contact with each other.

  Subsequently, the plurality of stacked wafers W are baked under a predetermined condition, so that the two wafers sandwiching the impurity supply source layer 120 are welded, and an impurity is supplied to each of the plurality of wafers W. Impurities (acceptors such as boron) contained in the source layer 120 are diffused (step S11C). As a result, as shown in step (D) of FIG. 2 described later, the p-type diffusion layer 121 is formed on each surface of the two wafers W in contact with the impurity supply source layer 120.

  Subsequently, the plurality of wafers W are separated on the surface on which the oxide film 110 is formed (step S11D). That is, the wafer W is separated on the surface where the oxide films 110 shown in the step (C) of FIG. As a result, as shown in step (D) of FIG. 2, a stacked body L obtained by stacking the two wafers W with the impurity supply source layer 120 interposed therebetween is obtained. The stacked body L has a structure in which two wafers W are welded via an impurity supply source layer 120. In other words, the stacked body L has a structure in which two wafers W are bonded and integrated through the impurity supply source layer 120. For this reason, each wafer W mutually complements the strength, and the mechanical strength of each wafer W constituting the stacked body L is higher than that of one wafer W.

  Next, processing for forming mesa grooves and passivation is performed on each main surface of the two wafers W forming the stacked body L prepared as described above by using a photolithography method (step S12). .

  Specifically, as shown in step (E) of FIG. 3, a photoresist 130 is applied on the oxide film 110 existing on one side of the wafer W that forms the above-described stacked body L, and the photoresist 130 is formed on the photoresist 130. Expose the mesa groove pattern. Then, the mesa groove pattern is formed in the oxide film 110 by etching the oxide film 110 using the photoresist 130 having the exposed mesa groove pattern as a mask (step S12A).

  Subsequently, as shown in step (F) of FIG. 3, the two wafers welded with the impurity source layer 120 sandwiched between the oxide film 110 having the mesa groove pattern and the photoresist 130 as a mask. By etching each main surface of W, a mesa groove 140 is formed on each main surface of these two wafers (step S12B). The mesa groove 140 has a depth reaching the p-type diffusion region 121 formed in the wafer W.

  Subsequently, as shown in step (G) of FIG. 3, after removing the photoresist 130, a passivation 150 that covers the mesa groove 140 is formed (step S12C). For example, glass is used as the passivation 150. As a result of forming the passivation 150, the mechanical strength of the wafer W in the mesa groove 140 is further reinforced.

  Subsequent to the processing for forming the mesa groove and passivation described above, the adhesion layer formed by the impurity source layer 120 is removed by hydrofluoric acid (HF) treatment. As a result, the two wafers W that have been subjected to the above-described processing are separated (step S13). In this embodiment, when removing the adhesion layer by the impurity source layer 120 with hydrofluoric acid (HF), the oxide film 110 in which the mesa groove pattern is formed is removed together with the adhesion layer by the impurity source layer 120. To do. Thus, it is not necessary to provide a separate process for removing the oxide film 110, and the number of processes can be reduced. Prior to the step of peeling the two wafers W, the mechanical strength of the mesa groove 140 is reinforced by the passivation 150 in the step (G) of FIG. In the process and each subsequent process, cracking of the wafer W and the like are suppressed.

  When the two wafers W are peeled as described above, the mesa groove 140 covered with the passivation 150 is formed on one surface side as shown in the step (H) of FIG. A wafer W on which the diffusion layer 121 is formed is obtained. In the cross-sectional structure of this wafer W, the n-type substrate region in which no impurity is diffused by the impurity supply source layer 120 corresponds to the n region in the pn junction of the mesa diode element, and the impurity by the impurity supply source layer 120 is diffused. The diffusion layer 121 corresponds to the p region in the pn junction.

  Next, following the step of peeling the wafer described above, as shown in step (I) of FIG. 4, electrodes 160 using nickel or the like are formed on both sides of the peeled wafer W (step S14). .

  Finally, as shown in step (J) of FIG. 4, the wafer W on which the electrode 160 is formed is divided into a plurality of chips along the mesa groove 140 (step S15). In the example shown in step (J) of FIG. 4, the electrode 160 on the upper surface of each chip serves as the cathode electrode of the mesa diode element, and the electrode 160 on the lower surface of each chip serves as the anode electrode of the mesa diode element. Each of these chips is incorporated into a package (not shown) to obtain a mesa diode element as a final product.

  Although the first embodiment of the present invention has been described above, according to the first embodiment, two wafers are formed until the step of forming the passivation 150 shown in step (G) of FIG. 3 (step S12C). W is welded through the impurity supply source layer 120. For this reason, if two welded wafers W are viewed as one structure, the mechanical strength thereof is higher than that of a single wafer, and therefore the cracking of the wafers W in the manufacturing process can be reduced. it can.

In addition, since the mesa groove 140 of the wafer W is reinforced by the passivation 150 after the passivation 140 is formed, the wafer W in the mesa groove 140 is peeled off after the two wafers W are separated after the formation of the passivation 150. Can be reduced.
Therefore, according to the first embodiment described above, it is possible to effectively reduce wafer cracks and chipping in the manufacturing process of a mesa diode element having a device structure in which an impurity diffusion layer is formed on one side of a chip. become.

  In the first embodiment described above, an n-type wafer is used as the wafer W, and an impurity supply source layer 120 including an acceptor such as boron is used. However, the present invention is not limited to this example. A p-type wafer may be used as W, and the impurity supply source layer 120 including a donor such as phosphorus may be used.

(Second Embodiment)
Next, the semiconductor device manufacturing method according to the second embodiment of the present invention will be described along the flow shown in FIG. 5 with reference to the process diagrams shown in FIGS.

The method for manufacturing a semiconductor device according to the second embodiment is a method for manufacturing a mesa diode element having a device structure in which different conductivity type impurity diffusion layers are formed on both surfaces of a chip.
In FIG. 5, steps S21A, S21B, S21C, and S21D show the detailed process of step S21, and steps S22A, S22B, and S22C show the detailed process of step S22.

  First, a laminated body formed by laminating two wafers with an impurity supply source layer interposed therebetween is prepared (step S21).

  More specifically, a plurality of wafers W including two wafers to be stacked are prepared, and as shown in step (A) of FIG. 6, the sheet-like first impurity supply source layer 220 and the second impurity source layer 220 and the second A plurality of wafers W are stacked with the impurity supply source layers 230 alternately interposed therebetween.

  Here, if attention is paid to one wafer W among a plurality of wafers W laminated by alternately sandwiching the first impurity supply source layer 220 and the second impurity supply source layer 230 described above, the entire surface of the wafer W can be seen as one surface. The first impurity source layer 220 is disposed on the other surface, and the second impurity source layer 230 is disposed on the other surface. If attention is paid to the two adjacent wafers W, One of the first impurity supply source layer 220 and the second impurity supply source layer 230 is disposed therebetween.

  In the present embodiment, the first impurity supply source layer 220 includes a donor such as phosphorus, and the second impurity supply source layer 230 includes an acceptor such as boron.

  As described above, by firing the plurality of wafers W stacked alternately with the first impurity supply source layer 220 and the second impurity supply source layer 230, the first impurity supply source layer 220 and the second impurity supply layer 220 are baked. Each wafer W is welded through the supply source layer 230, and each impurity contained in the first impurity supply source layer 220 and the second impurity supply source layer 230 is diffused into a plurality of wafers W (step S21A). As a result, as shown in step (B) of FIG. 6 to be described later, the first impurity supply source is formed on one side of each of the two wafers W welded via the second impurity supply source layer 230. An n-type diffusion layer 221 is formed by the layer 220, and a p-type diffusion layer 231 is formed by the second impurity supply source layer 230 on the other surface side.

  Subsequently, by selectively removing the first impurity supply source layer 220, a plurality of wafers W are separated on the surface on which the first impurity supply source layer 220 is disposed. In the present embodiment, the selective removal of the first impurity supply source 220 is performed, for example, by controlling the processing time. That is, under the same processing conditions, the decomposition rate of the welded layer by the first impurity source layer 220 and the decomposition rate of the welded layer by the second impurity source layer 230 are different, and such a difference in decomposition rate is used. Then, the first impurity supply source 220 is selectively removed. In this embodiment, under the same processing conditions, the weld layer formed by the first impurity source layer 220 is dissolved faster than the weld layer formed by the second impurity source layer 230. Using the property, only the first impurity supply source 220 is selectively removed.

  In the above example, the first impurity supply source 220 is selectively removed. However, the present invention is not limited to this example, and each impurity supply source is selectively removed so that the second impurity supply source layer 230 is selectively removed. A layer may be selected.

  By selectively removing the first impurity source layer 220 as described above, as shown in step (B) of FIG. 6, two wafers that are welded with the second impurity source layer 230 sandwiched therebetween. Get W. However, at this stage, a part of the weld layer formed by the first impurity supply source layer 220 remains on the main surface of the wafer W.

  Subsequently, the welding layer formed by the first impurity supply source layer 220 is removed from the two wafers W thus welded, and thereby the second impurity supply source layer 230 as shown in step (C) of FIG. A laminated body LL obtained by laminating two wafers W with the wafer interposed therebetween is obtained. The two wafers W of the stacked body LL have a structure in which the two wafers W are welded via the second impurity supply source layer 230. For this reason, the mechanical strength of each wafer W which comprises the laminated body LL is high.

  Next, processing for forming mesa grooves and passivation is performed on each main surface of the two wafers W forming the stacked body LL prepared as described above by using a photolithography method (step S22). ).

  Specifically, as shown in step (D) of FIG. 7, an oxide film 240 is formed on the main surface of each wafer W forming the stacked body LL. Then, a photoresist 250 is applied on the oxide film 240, and a mesa groove pattern is exposed on the photoresist 250. Then, as shown in FIG. 7E, the oxide film 240 is etched using the photoresist 250 exposed to the mesa groove pattern as a mask, thereby forming a mesa groove pattern in the oxide film 240 (step). S22A).

  Subsequently, as shown in FIG. 7 (F), two wafers welded with the second impurity supply source layer 220 sandwiched between the oxide film 240 having the mesa groove pattern and the photoresist 250 as a mask. Each main surface of W is etched using a sand blast method or the like, thereby forming a mesa groove 260 in each main surface of these two wafers (step S22B).

  Subsequently, as shown in step (G) of FIG. 8, after removing the photoresist 250, a passivation 270 that covers the mesa groove 260 is formed (step S22C). For example, glass is used as the passivation 270. As a result of forming the passivation 270 in this way, the mechanical strength of the wafer W in the mesa groove 260 is reinforced.

  Following the processing for forming the above mesa groove, as shown in FIG. 8H, the two wafers W subjected to the processing are separated (step S23). In the present embodiment, the two wafers W are separated by removing the fusion layer formed by the second impurity supply source layer 230 using a hydrofluoric acid (HF) process. At this time, the oxide film 240 in which the mesa groove pattern is formed is removed together with the adhesion layer formed by the second impurity supply source layer 230. Thereby, the number of processes can be reduced.

  Subsequent to the step of peeling the wafer W described above, as shown in step (I) of FIG. 8, electrodes 280 using nickel or the like are formed on both surfaces of the peeled wafer W (step S24).

  Subsequently, as shown in step (J) of FIG. 8, the wafer on which the electrode 280 is formed is divided into a plurality of chips T along the mesa groove 260 (step S25).

  In the example shown in step (J) of FIG. 8, the electrode 280 on the upper surface of each chip is the cathode electrode of the mesa diode element, and the electrode 280 on the lower surface of each chip is the anode electrode of the mesa diode element. Each of these chips T is incorporated into a package (not shown) to obtain a mesa diode element as a final product.

  As described above, in the present invention, in order to solve the above-described problem, the step of removing the adhesion layer is provided after the diffusion (for example, after the passivation is formed). In the case of simultaneous diffusion on both sides, only the welded layer that easily peels off after diffusion is peeled off. As a result, the wafer undergoes a photographic process, a groove forming process, and a passivation process in a set of two sheets. If a material with mechanical strength (for example, glass) is selected as the passivation, the mesa groove is reinforced by the passivation after the formation of the passivation. Hateful. In addition, since the adhesion layer can be removed simultaneously with the removal of the oxide film after the passivation is formed, the number of steps can be reduced. Thereafter, by forming electrodes and dividing the chip, a chip having a desired thickness can be obtained.

  Even in the processes after the diffusion process, the wafers are processed as a laminated body without removing the wafers one by one, so that mechanical strength can be ensured even for thinned and enlarged wafers. , It is possible to prevent cracks and chips accompanying processing.

  Moreover, by changing the process of peeling the welding surfaces between wafers from the process after the conventional diffusion process to the process after the passivation formation process, it can be performed simultaneously with the oxide film removal, and the number of processes can be reduced. it can. Therefore, it is possible to manufacture a mesa diode element at a low cost without accompanying an increase in new manufacturing processes, and it is possible to prevent cracking and chipping of the wafer in the manufacturing process.

  W ... wafer, L, LL ... stack, S11-S15 ... step, S21-S25 ... step, 110 ... oxide film, 120 ... impurity source layer, 121 ... p-type diffusion layer, 130 ... photoresist, 140 ... mesa Groove 150 ... Passivation 160 ... Electrode 220 ... First impurity source layer 221 ... N-type diffusion layer 230 ... Second impurity source layer 231 ... P-type diffusion layer 240 ... Oxide film 250 ... Photo Resist, 260 ... mesa groove, 270 ... passivation, 280 ... electrode.

Claims (7)

A step of preparing a laminated body formed by laminating two wafers with an impurity supply source layer sandwiched therebetween, wherein the laminated body has a structure in which the two wafers are welded through the impurity supply source layer; ,
A step of processing each main surface of the two wafers forming the laminate;
And a step of peeling the two wafers that have been subjected to the processing. The step of processing each main surface of the two wafers,
Forming a mesa groove on each main surface of the two wafers using an oxide film on which a pattern for the mesa groove is formed as a mask;
A method for manufacturing a semiconductor device according to claim 1, further comprising: forming a passivation that covers the mesa groove. The step of peeling the two wafers includes:
The method for manufacturing a semiconductor device according to claim 2, further comprising a step of removing the oxide film together with the adhesion layer formed by the impurity source layer. After the step of peeling the two wafers,
Forming electrodes on both surfaces of each of the peeled wafers;
The method for manufacturing a semiconductor device according to claim 2, further comprising: dividing each wafer on which the electrodes are formed into a plurality of chips along the mesa groove. The step of preparing the laminate includes
Forming an oxide film on both surfaces of a plurality of wafers including the two wafers;
Removing the oxide film from one side of the plurality of wafers;
By laminating the plurality of wafers across the impurity supply source layer on the surface from which the oxide film has been removed, and firing the plurality of laminated wafers, two sheets sandwiching the impurity supply source layer A step of welding the wafer and diffusing impurities contained in the impurity source layer into the plurality of wafers;
5. The method of manufacturing a semiconductor device according to claim 1, further comprising: separating the plurality of wafers on a surface on which the oxide film is disposed to obtain the stacked body. The step of preparing the laminate includes
Laminating the plurality of wafers by alternately sandwiching a first impurity supply source layer and a second impurity supply source layer as the impurity supply source layer between the plurality of wafers including the two wafers; By firing the plurality of wafers thus formed, two wafers sandwiching the second impurity supply source layer are welded, and each of the plurality of wafers included in the first and second impurity supply source layers A step of diffusing impurities;
Separating the plurality of wafers at a surface on which the first impurity source layer is located, and obtaining two wafers that are welded with the second impurity source layer interposed therebetween;
5. The method of manufacturing a semiconductor device according to claim 1, further comprising: removing the weld layer formed by the first impurity supply source layer from the two welded wafers to obtain the stacked body. Method.   A semiconductor device manufactured by the manufacturing method according to claim 1.

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