JP2010045148A - Method of manufacturing laminated wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a laminated wafer, can produce a laminated wafer having a high-quality active layer which does not have contamination by heavy metals. <P>SOLUTION: In a method, a wafer for an active layer and a wafer for a supporting layer are laminated to manufacture a laminated wafer, and in a process of reducing the thickness of the wafer for the active layer of the laminated wafer by at least grinding, the grinding damage is removed after the grinding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a bonded wafer, and more particularly, to a method for manufacturing a bonded wafer in which heavy metal contamination of an active layer wafer portion of the bonded wafer is prevented.

  As a general method for manufacturing a bonded wafer, another silicon wafer is bonded to one silicon wafer on which an oxide film (insulating film) is formed, and one of the bonded silicon wafers is ground. Polishing to form an SOI (Silicon On Insulator) layer (grinding polishing method) or implanting oxygen ions into the silicon wafer and then performing high-temperature annealing to fill the silicon wafer with a buried oxide film (BOX ) Layer is formed, and the upper part of the BOX layer is made an SOI layer (SIMOX: Separation by Implanted Oxygen method), and hydrogen ions are implanted into the surface layer part of the silicon wafer (active layer wafer) on the SOI layer side. After forming the ion implantation layer, the silicon wafer is bonded to the silicon wafer for the support substrate, and then peeled off by the above ion implantation layer by heat treatment. A method of forming an SOI layer by forming (smart cut method) or the like is known (for example, refer to Patent Document 1 for the SIMOX method).

  However, each of the above methods has a problem that the film thickness uniformity of the active layer is inferior (± 30% or more).

Therefore, in order to solve the above problem, the present inventors firstly combined the oxygen ion implantation method and the grinding and polishing method, that is, "active layer wafer with or without an insulating film on the surface, A method for producing a bonded wafer comprising directly bonding to a support layer wafer and then thinning the active layer wafer portion,
Injecting oxygen ions into the active layer wafer to form an oxygen ion implanted layer in the active layer;
A step of heat-treating the active layer wafer at a temperature of 1100 ° C. or higher in a non-oxidizing atmosphere;
Bonding the active layer wafer and the support layer wafer together;
A heat treatment step for improving the bonding strength of the bonded wafers;
Grinding the wafer part for the active layer of the bonded wafer to the front of the oxygen ion implantation layer;
Further polishing or etching the wafer portion for the active layer of the bonded wafer to expose the oxygen ion implantation layer;
Oxidizing the bonded wafer to form an oxide film on the exposed surface of the oxygen ion implantation layer; and
Removing the oxide film;
Applying a heat treatment at a temperature of 1100 ° C. or less in a non-oxidizing atmosphere to flatten the wafer portion for the active layer of the bonded wafer;
A method for producing a bonded wafer, characterized in that the time-series coupling is as follows. "
Was developed and disclosed (see Patent Document 2).
According to this method, it is possible to provide a directly bonded wafer having relatively excellent thickness uniformity of the active layer and relatively few defects as evaluated by a transmission electron microscope (TEM).
JP-A-5-291543 JP 2008-16534 A

  However, in the method disclosed in Patent Document 2, in the process of grinding the wafer portion for the active layer of the bonded wafers to the front of the oxygen ion implanted layer, the Si wafer is actually used with a grindstone having a roughness of # 100 to # 3000. At this time, the surface of the Si wafer is distorted. The depth of this strain is about 5 μm at maximum although it depends on the roughness of the grindstone. In the above grinding process, simultaneously with grinding of the Si wafer, heavy metals such as Fe, Ni, and Cu are rubbed into this strain. Similar heavy metals are also adhered to the grinding marks.

When this wafer is polished as it is, the distortion of the surface is promoted by polishing, and the distortion remains on the surface of the polished Si wafer, and this distortion also remains on the surface of the bonded wafer that is the final product. The heavy metal in the strained layer also remains, and the surface of the Si wafer is contaminated with heavy metal.
Further, since there is a heat treatment step after polishing, the heavy metal in the surface strain layer diffuses into the Si wafer by the heat treatment.
Moreover, in the bonded wafer manufacturing process, the thickness of the active layer is usually 2 μm or less.
Therefore, in the conventional method, there is a problem that the heavy metal contamination has an influence on the quality of the active layer, and when the active layer is a thin film, the influence on the quality becomes more remarkable.

  In order to solve this problem, it is possible to reduce the Si wafer to a predetermined thickness by polishing instead of grinding. However, this is too time consuming and increases the cost, and the wafer shape also collapses. Problems arise.

  An object of the present invention is to solve the above-mentioned problems advantageously, and to propose an advantageous method for manufacturing a bonded wafer, in which heavy metal contamination of the wafer portion for the active layer of the bonded wafer is prevented. To do.

Now, as a result of intensive studies on the removal of heavy metals, the present inventor has obtained the knowledge that it is desirable to remove them by etching.
The present invention is based on the above findings.

That is, the summary structure of the manufacturing method of the bonded wafer of this invention is as follows.
1. A method for manufacturing a bonded wafer by bonding an active layer wafer and a support layer wafer,
(1) bonding the active layer wafer and the support layer wafer directly or through an insulating film;
(2) a step of thinning at least the wafer portion for the active layer of the bonded wafer by grinding;
Including a series of processes including
(2) A method for producing a bonded wafer, characterized in that grinding damage is removed after the grinding in the step of reducing the thickness of the active layer wafer portion of the bonded wafer.

2. (2) In the step of reducing the thickness of the wafer portion for the active layer of the bonded wafer, as a method for removing the grinding damage, at least one of alkali etching, acid etching, and gas etching is used. The method for producing a bonded wafer according to claim 1.

3. Before the step of bonding the active layer wafer and the support layer wafer in (1) above, an oxygen ion implantation is performed on the active layer wafer to form an oxygen ion implanted layer,
In the step of reducing the thickness of the wafer portion for the active layer of the bonded wafer of (2), after removing the grinding damage, the oxygen ion implanted layer is polished as a polishing stop layer, and then the oxygen ion implanted The method for producing a bonded wafer according to claim 1, wherein the layer is removed.

  In the present invention, since the wafer portion for the active layer of the bonded wafer is at least thinned by grinding, grinding damage, that is, grinding distortion, is removed after the grinding, so that the active layer remains even after polishing or heat treatment. No contamination with heavy metals.

  Therefore, according to the present invention, a bonded wafer having a high-quality active layer free from contamination by heavy metals can be produced.

  In addition, it is preferable to use at least one of alkali etching, acid etching, and gas etching as the method for removing the grinding damage in the rapid heating / cooling heat treatment. If any one of alkali etching, acid etching, and gas etching is used or a combination of these etchings is used as appropriate, unevenness on the wafer surface can be removed, so that grinding strain is removed and heavy metal within the strain is removed. Can also be removed.

  Further, before the step of bonding the active layer wafer and the support layer wafer, oxygen ion implantation is performed on the active layer wafer to form an oxygen ion implanted layer, and then the bonded wafers for the active layer In the step of reducing the thickness, after removing grinding damage, it is preferable to perform polishing using the oxygen ion implanted layer as a polishing stop layer and then remove the oxygen ion implanted layer. Since the heavy metal can be removed by removing grinding damage, the wafer surface is not contaminated with heavy metal by polishing using the oxygen ion implanted layer as a polishing stop layer, so high quality and extremely thin activity without heavy metal contamination A bonded wafer with layers can be manufactured.

Hereinafter, embodiments of the present invention will be specifically described.
First, the bonded wafer as a target in the present embodiment and each manufacturing process of the present embodiment according to the process flow shown in FIG. 1 will be specifically described.
-Bonded wafer In order to produce a bonded wafer according to this embodiment, two silicon wafers, an active layer wafer and a support layer wafer, are bonded together. In this embodiment, both wafers are bonded together. In this case, the present invention can be applied not only to the case where an insulating film (oxide film) is interposed, but also to the case of directly bonding without using such an insulating film.
Note that the type, concentration, oxygen concentration, and the like of the dopant are not limited as long as the bonded wafer has good surface roughness suitable for bonding. However, in order to further reduce defects, a wafer having no or few COPs (Crystal Oriented Particles) is preferable. Here, COP can be reduced by optimizing the CZ pulling conditions to reduce COP, performing high-temperature heat treatment at 1000 ° C or higher in a reducing atmosphere after wafer mirror processing, and epitaxially growing Si on the wafer by CVD or the like. Methods etc. can be applied.

(1) Step of implanting oxygen ions into active layer wafer First, in this embodiment, oxygen ions are implanted into an active layer wafer.
In the present embodiment, the acceleration voltage at the time of oxygen ion implantation can be appropriately selected according to the thickness of the active layer of the final product, and is not particularly limited. Accordingly, the acceleration voltage of a normal oxygen ion implanter may be about 100 to 300 keV.
On the other hand, in this embodiment, oxygen ion implantation is performed by setting the substrate temperature to a high temperature of 200 ° C. or higher (for example, 450 ° C.) and setting the dose amount to 1.0 × 10 ^{16 to} 3.0 × 10 ¹⁷ atoms / cm ^2. .

If the dose amount during oxygen ion implantation is less than 1.0 × 10 ¹⁶ atoms / cm ² , the Si amorphous layer containing oxygen atoms in the oxygen ion implanted layer after the heat treatment in the heat treatment step (2) is a single layer. Since the two-layer structure is not formed in one layer or is not sufficiently formed and the SiO ₂ particles are too far apart, the wafer portion for the active layer is formed in the step (4) after bonding, which will be described later. Since the SiO ₂ particles easily fall off during polishing to reduce the thickness, the polishing cannot be stopped accurately.
On the other hand, when the dose amount during the oxygen ion implantation is greater than 3.0 × 10 ¹⁷ atoms / cm ^2, since the high oxygen is required at the time of oxygen ion implantation, the cost to the oxygen ion implantation will piling up.

Note that the oxygen ion implantation at the high temperature may be divided into a plurality of divided implantations, and cleaning may be performed between the divided implantations. As the cleaning method, SC1, HF, O ₃ and organic acid cleaning, scrub cleaning, etc., which are excellent in particle removal capability, are suitable.

(2) Step of heat-treating wafer for active layer Next, in this embodiment, heat treatment is performed at a temperature of 1100 ° C. or higher and 1250 ° C. or lower for 10 minutes or more at the stage before bonding. If the temperature is less than 1100 ° C., the oxygen ion implanted layer is not combined into a single layer but has a two-layer structure, or is not sufficiently amorphous, and the polishing stop function is not sufficiently high.
On the other hand, at temperatures exceeding 1250 ° C., slip transition may occur.
During this heat treatment, by processing in a non-oxidizing atmosphere, oxygen implanted near the outermost surface during oxygen ion implantation is diffused outward to lower the oxygen concentration, and oxygen near the outermost surface during bonding strengthening heat treatment This contributes to the suppression of precipitates, and as a result, the defect density can be further reduced. As the non-oxidizing atmosphere, Ar, H ₂ or a mixed atmosphere thereof is advantageously adapted.

(3) Step of bonding the active layer wafer and the support layer wafer Next, in this embodiment, the active layer wafer and the support layer wafer are bonded together, but this bonding may be performed through an insulating film. However, it can also be bonded directly without using an insulating film.
When bonding is performed through an insulating film, an oxide film (SiO ₂ ) such as a BOX, a nitride film (Si ₃ N ₄ ), or the like is preferable as the insulating film. As a film forming method, heat treatment (thermal oxidation, thermal nitridation), CVD, or the like in an oxidizing atmosphere or a nitrogen atmosphere is preferable. As thermal oxidation, in addition to oxygen gas, wet oxidation using water vapor or the like can also be used.
Further, the insulating film may be formed before oxygen ion implantation or after implantation.

Further, before bonding, it is advantageous to perform a cleaning process in order to suppress generation of voids due to particles.
As a cleaning method, SC1 + SC2, HF + O ₃ , an organic acid, or a combination thereof, which is a general silicon wafer cleaning method, is effective.
Furthermore, if the bonding strength is not sufficient at a bonding temperature of 1000 ° C or less and there is a risk of peeling depending on the conditions (pressure / speed) of the grinding / polishing process after bonding, the bonding strength should be increased. In order to increase the thickness, it is advantageous to subject the silicon surface before bonding to an activation treatment using plasma using oxygen, nitrogen, He, H ₂ , Ar, or a mixed atmosphere thereof.

In the case of direct bonding, H ₂ O adsorbed on the bonding surface changes to SiO ₂ in the subsequent heat treatment and exists at the bonding interface, so the bonding surface is washed with HF, and hydrophobic surface bonding is performed. go and may be carried out a method of inhibiting the SiO _2. Thereby, the oxide at the interface can be reduced, which leads to improvement of device characteristics.

(4) Heat treatment step for improving the bonding strength Next, in this embodiment, a heat treatment for increasing the bonding strength is performed. This heat treatment is performed at a temperature of 1000 ° C. or higher in order to sufficiently increase the bond strength, but the holding time is preferably within 1 h. Although the atmosphere is not particularly limited, it is preferable to provide an oxide film having a thickness of 150 nm or more as the oxidizing atmosphere in order to protect the back surface of the wafer in the next grinding step.

(5) Step of reducing the thickness of the active layer wafer and exposing the oxygen ion implanted layer In this embodiment, the thickness of the active layer wafer is then reduced by grinding and polishing to expose the oxygen ion implanted layer.

・ Grinding The active layer wafer of the bonded wafer is ground by mechanical processing. In this grinding, a part of the active layer wafer is left on the surface side of the oxygen ion implanted layer. The film thickness of a part of the remaining active layer wafer is not limited.
In order to shorten the polishing process time in the subsequent process, it is preferable to perform grinding until just before the oxygen ion implanted layer. However, the accuracy of the grinding apparatus, the damage depth (about 2 μm) due to grinding, and etching in the next process are considered Then, the residual film Si thickness is preferably about 6 to 10 μm.

Etching Subsequent to grinding, the surface of the wafer for active layer of the bonded wafer is etched to remove grinding damage (grinding distortion).
This etching uses one of alkali etching of 40 ± 5% KOH, acid etching using hydrofluoric acid, nitric acid and phosphoric acid, and gas etching using CF ₄ , O ₂ and N ₂ . Etching is used in combination as appropriate, such as alkali etching or acid etching followed by gas etching, or gas etching first and then alkali etching or acid etching.
When etching, particularly preferably alkaline etching, is performed, the irregularities on the wafer surface can be removed, so that grinding strain can be removed and heavy metals in the strain can also be removed.
As the alkaline solution for the alkali etching, an inorganic alkaline solution (KOH, NaOH, etc.), an organic alkaline solution (for example, piperazine or ethylenediamine containing amine as a main component) or a mixed solution thereof is suitable.

  In particular, by etching Si before polishing, the boundary between the terrace (the outermost 1 to 3 mm area where the two wafers are not bonded together) and the bonded area becomes smooth, and the generation of particles is suppressed.

-Polishing Following etching, the wafer for active layer of the bonded wafer is polished to expose the oxygen ion implanted layer.
This polishing method is preferably performed while supplying an abrasive having an abrasive concentration of 1% by mass or less. Examples of such a polishing liquid include an alkaline solution having an abrasive grain (for example, silica) concentration of 1% by mass or less. As the alkaline solution, an inorganic alkaline solution (KOH, NaOH, etc.), an organic alkaline solution (for example, piperazine containing ethylene as a main component, ethylenediamine, etc.) or a mixed solution thereof is suitable as in the previous alkali etching. .
In this polishing method, the abrasive concentration is 1% by mass or less, and therefore there is almost no mechanical polishing action by the abrasive grains, and the chemical polishing action is prioritized. And a part (Si layer) of the wafer for active layers is grind | polished by the chemical grinding | polishing effect | action by this alkaline solution. Since the alkaline solution has a high etching rate ratio of Si / (Si amorphous layer containing oxygen atoms), the Si layer that is part of the wafer for the active layer can be polished efficiently, but contains oxygen atoms. The Si amorphous layer is hardly polished. Therefore, even if the mechanical accuracy of the polishing apparatus is not sufficient, the oxygen ion implanted layer is hardly polished, and only the Si layer is polished. As a result, the oxygen ion implanted layer can be uniformly exposed.
That is, the oxygen ion implanted layer in the present embodiment functions as a polishing stop layer having a sufficiently high polishing stop function.

(6) Oxygen ion implantation layer removal step In this embodiment, the exposed oxygen ion implantation layer is then removed. This oxygen ion implantation layer is made of Si amorphous containing oxygen atoms, partially recrystallized Si, and SiO ₂ . As a removal method, an etching method, an oxidation + etching method, polishing, or the like can be applied.
・ Etching method Oxygen dose and heat treatment are required for the oxygen ion implanted layer to become a complete SiO ₂ layer (BOX layer), but because of insufficient conditions, SiO ₂ is removed for etching. HF solution, etching conditions such as to alternately and HF solution to remove the alkaline solution SiO ₂ to or Si was produced by oxidizing an SC1 solution or ozone solution to oxidize and remove the Si is preferred.
In any case, after immersing in the HF solution and using the HF solution, it is preferable to repeat the oxidation + HF until the entire wafer surface becomes a water-repellent surface, which is a measure for removing SiO ₂ .

Oxidation method This method comprises a step of forming an oxide film having a predetermined thickness on the exposed surface of the oxygen ion implanted layer and a step of removing the oxide film.
This oxidation treatment may be performed in an oxidizing atmosphere, and the treatment temperature is not particularly limited, but is preferably an oxidizing atmosphere at 600 to 1000 ° C.
However, in order to suppress the deterioration of the surface roughness due to the SiO ₂ particles generated by recrystallization of the amorphous of the oxygen ion implanted layer, it is preferable to perform the treatment at a low temperature, more preferably 600 to 900 ° C. .
When performing oxidation treatment at low temperature, we can apply wet oxidation using H ₂ O vapor or hydrochloric acid oxidation of oxidizing gas treatment containing HCl gas to increase the growth rate of the oxide film, and high throughput is achieved. More preferred for obtaining.
The thickness of the oxide film is not particularly limited. However, when a crystal defect layer is present in the oxygen ion implanted layer, it is preferable to set the thickness to be equal to or greater than the thickness. Is preferably about 100 to 500 nm. If the thickness of the oxide film is less than 100 nm, the Si amorphous layer cannot be sufficiently removed under the oxygen ion implantation conditions of the present embodiment, while if it exceeds 500 nm, the active layer is broken due to the collapse of the in-plane uniformity of the oxide film. The film thickness uniformity deteriorates.
In order to remove the oxide film, cleaning with HF solution or etching by annealing using hydrogen gas, Ar gas, or gas containing HF may be used. Here, the above oxidation treatment and removal treatment may be performed a plurality of times. As a result, it is possible to further reduce the thickness of the active layer while maintaining the flattened surface roughness.
After removing the oxide film, for example, it is advantageous to immerse the bonded wafer in a mixed solution of organic acid and hydrofluoric acid to remove particles and metal impurities adhering to the surface of the bonded wafer.

(7) Planarization and / or thinning step of wafer surface for active layer In this embodiment, the surface of the wafer for active layer is then planarized.
Since the bonded wafer surface after removal of the oxygen ion implanted layer is rough as compared with mirror polishing, it is desirable to make it flat.
As a planarization method, heat treatment in a reducing atmosphere, gas etching made of gas, ions, radicals, etc. capable of polishing and Si etching can be applied.
・ Polishing method The surface to be bonded is slightly polished to improve roughness. The polishing allowance is preferably about 10 to 500 nm. If the thickness is less than 10 nm, the roughness cannot be improved sufficiently, while if it exceeds 500 nm, the film thickness uniformity of the active layer deteriorates. By this treatment, the surface roughness (RMS) can be reduced to 0.5 nm or less.

・ Reducing atmosphere heat treatment
Ar, by heat treatment with H ₂ or in a mixed atmosphere thereof, for improving the roughness of the bonded wafer surface. The treatment temperature is preferably about 1000 ° C to 1300 ° C. The treatment time needs to be longer as the temperature is lower, preferably about 1 to 2 hours at 1000 to 1200 ° C, about 10 to 30 minutes at 1200 to 1250 ° C, and about 1 to 5 minutes at 1250 or more. When heat treatment is performed at a high temperature for a long time exceeding the above temperature and time, the in-plane uniformity of the active layer may be deteriorated due to the etching action in the reducing atmosphere.
In this embodiment, since the residence time in the temperature range of 1000 ° C. or higher after the bonding until the removal of the oxygen ion implanted layer is limited to within 1 h, sufficient bonding strength is not always obtained. Accordingly, a planarization treatment at a temperature of 1100 ° C. or higher that improves the bonding strength after removing the oxygen ion implanted layer is more preferable.
When surface activation is performed by plasma or the like in the pre-bonding treatment, heat treatment at 1100 ° C. or higher is not necessarily required.
As the heat treatment furnace, a resistance heating type vertical furnace capable of processing a plurality of sheets at the same time or a lamp heating type RTA (high speed heating / cooling furnace) for processing each sheet is suitable. In particular, RTA is effective for treatments above 1200 ° C.
By the above heat treatment, the surface roughness (RMS) can be reduced to 0.5 nm or less, as in the case of the polishing method.
The removal of the surface oxide film generated by this heat treatment may be performed by cleaning with HF liquid, or etching by annealing using a gas containing hydrogen gas, Ar gas, or HF.

  Thus, according to the present embodiment, it is possible to obtain a bonded wafer that is excellent in film thickness uniformity, has few defects, and has a markedly improved surface roughness.

An example in which a bonded wafer is manufactured based on the method of the present embodiment and a comparative example in which a bonded wafer is manufactured by a conventional method will be described below.
Two silicon wafers with a diameter of 300 mm, sliced from a silicon ingot grown with the CZ method and boron as a dopant, were prepared in 2 x 2 sets, one set as an example and one set as a comparative example. One silicon wafer was used as an active layer wafer, and the other silicon wafer was used as a support layer wafer.
In both the examples and comparative examples, the active layer wafer was heat-treated at 1000 ° C. for 3 hours in an oxidizing atmosphere to form an oxide film having a thickness of 150 nm.
Next, oxygen ions were implanted at an acceleration voltage of 200 keV from the surface of the active layer wafer in both the examples and the comparative examples. At this time, in both the example and the comparative example, the substrate temperature was set to 450 ° C., and the dose amount was set to 1.2 × 10 ¹⁷ atoms / cm ² .
As a result, an oxygen ion implanted layer was formed at a depth of about 600 to 800 nm from the surface of the active layer wafer in both the examples and comparative examples.
Next, in both the examples and comparative examples, the wafer for active layer was subjected to heat treatment (annealing) before bonding in a non-oxidizing (Ar) atmosphere at 1200 ° C. × 1 hr (hour).

Next, HF + ozone cleaning was performed on both wafers in each group to remove particles on the bonding surface, and then both wafers in each group were bonded.
Thereafter, post-bonding heat treatment (annealing) was performed to firmly bond the bonding interfaces of both wafers in each group. The heat treatment was performed at 1000 ° C. for 1 hour in an oxidizing gas atmosphere, and an oxide film having a thickness of about 150 nm was formed on the front and back surfaces of the bonded wafer to form a back surface protective film during post-processing.
Next, the active layer wafer of each bonded wafer was ground by a predetermined thickness from the surface using a grinding apparatus. That is, a grinding process was performed to leave only a part of the active layer wafer (film thickness of about 5 μm) on the surface side of the oxygen ion implanted layer.

  Subsequently, only the wafer for active layer of the bonded wafer of the example was subjected to alkali etching with an alkaline solution for 10 minutes. This alkaline solution is 40% KOH. Next, in both the Examples and Comparative Examples, the surface of each bonded wafer after grinding was polished while supplying a polishing agent containing abrasive grains having an abrasive grain (silica) concentration of 1% by mass or less, and an oxygen ion implanted layer was formed. Exposed. As an abrasive | polishing agent, the alkaline solution whose abrasive grain concentration is 1 mass% or less was used. This alkaline solution is 40% KOH as in the previous alkaline etching.

  Table 1 below shows the evaluation results (AAS evaluation) of the heavy metal contamination (contamination) level of the bonded wafers of Examples and Comparative Examples obtained as described above. Also from this table, it can be seen that according to the examples of the present invention, contamination of heavy metals such as Fe, Ni and Cu can be prevented as compared with the comparative examples.

  Thus, according to the method for producing a bonded wafer of the present invention, since the active layer wafer portion of the bonded wafer is at least thinned by grinding, grinding damage, that is, grinding distortion is removed after the grinding. Even if polishing or heat treatment is performed, the active layer is not contaminated with heavy metal, and therefore, a bonded wafer having a high-quality active layer free from heavy metal contamination can be produced.

It is a figure which shows the process flow of one Embodiment of this invention.

Claims (3)

A method for manufacturing a bonded wafer by bonding an active layer wafer and a support layer wafer,
(1) bonding the active layer wafer and the support layer wafer directly or through an insulating film;
(2) a step of thinning at least the wafer portion for the active layer of the bonded wafer by grinding;
Including a series of processes including
(2) A method for producing a bonded wafer, characterized in that grinding damage is removed after the grinding in the step of reducing the thickness of the active layer wafer portion of the bonded wafer.   (2) In the step of reducing the thickness of the wafer portion for the active layer of the bonded wafer, as a method for removing the grinding damage, at least one of alkali etching, acid etching, and gas etching is used. The method for producing a bonded wafer according to claim 1. Before the step of bonding the active layer wafer and the support layer wafer in (1) above, an oxygen ion implantation is performed on the active layer wafer to form an oxygen ion implanted layer,
In the step of reducing the thickness of the wafer portion for the active layer of the bonded wafer of (2), after removing the grinding damage, the oxygen ion implanted layer is polished as a polishing stop layer, and then the oxygen ion implanted The method for producing a bonded wafer according to claim 1, wherein the layer is removed.

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