JP5910352B2 - Manufacturing method of bonded wafer - Google Patents

Description

  The present invention relates to a method for manufacturing a bonded wafer for improving film thickness uniformity of a thin film (SOI layer) of a bonded wafer using an ion implantation separation method.

  As one of semiconductor device wafers, there is an SOI (Silicon On Insulator) wafer in which a silicon layer is formed on a silicon oxide film that is an insulating film. In this SOI wafer, a silicon layer (hereinafter sometimes referred to as an SOI layer) in the surface layer portion of the substrate serving as a device manufacturing region is electrically separated from the inside of the substrate by a buried oxide film layer (BOX layer). It has features such as small capacity and high radiation resistance. Therefore, effects such as high-speed and low-power consumption operation and prevention of soft errors are expected, and it is promising as a substrate for high-performance semiconductor elements.

Typical methods for manufacturing this SOI wafer include a wafer bonding method and a SIMOX method.
In the wafer bonding method, for example, after forming a thermal oxide film on one surface of two silicon single crystal wafers, the two wafers are brought into close contact with each other through the formed thermal oxide film, and a bonding heat treatment is performed. In this method, the bonding force is increased, and then one wafer (a wafer on which an SOI layer is formed (hereinafter referred to as a bond wafer)) is thinned by mirror polishing or the like to manufacture an SOI wafer.

  As a method for thinning, a bond wafer is ground and polished to a desired thickness, or at least one of hydrogen ions or rare gas ions is implanted into the bond wafer in advance to form an ion implantation layer. There is a method called an ion implantation separation method in which the bond wafer is separated from the ion implantation layer after bonding.

  On the other hand, in the SIMOX method, oxygen is ion-implanted into a single crystal silicon substrate, followed by high-temperature heat treatment (oxide film formation heat treatment), and the implanted oxygen and silicon are reacted to form a BOX layer (buried oxide film layer). ) To form an SOI substrate.

Of the two typical methods described above, the wafer bonding method has the advantage that the thickness of the SOI layer and BOX layer to be fabricated can be set freely, so it can be applied to various device applications. It is.
In particular, the ion implantation delamination method, which is one of the wafer bonding methods, is characterized by having excellent film thickness uniformity in addition to the above advantages, and can obtain stable device characteristics over the entire wafer surface.

  However, in the ion implantation separation method, since ions are implanted into a single crystal material having a crystal orientation, if ions are implanted without considering the channeling effect, some ions are implanted deeper. Deterioration of the uniformity of the implantation depth and a decrease in the concentration of the implantation peak position occur, resulting in problems such as deterioration of the film thickness uniformity after peeling or inability to peel off.

As a countermeasure, a silicon wafer made of a single crystal material having a (100) orientation has an ion implantation angle of 7 degrees, thereby increasing the collision probability between the ions and the single crystal material, uniformity of implantation depth, It is known that the injection amount uniformity can be improved (Non-patent Document 1).
As a countermeasure, it is known that, for example, by forming an oxide film made of amorphous on the surface of a single crystal material, channeling can be suppressed by randomly changing the ingress direction of ions in the amorphous layer (non-non-crystalline). Patent Document 1).

  In Patent Document 1 (Claim 3 and FIG. 2), in order to reduce microvoids caused by particles adhering to the ion implantation surface, the hydrogen ion implantation is divided into a plurality of portions and the ion implantation angle is changed. Ion implantation is described. In particular, in Example 2, it is described that hydrogen ion implantation is divided into two and ion implantation is performed at ± 15 degrees.

WO2001 / 093334

The ion implantation technology that has come so far Genshu Fuse Industrial Research Committee 1991

The demand for film thickness uniformity of thin films of bonded wafers produced by the ion implantation delamination method is becoming stricter year by year.
In the case of manufacturing a bonded wafer by the ion implantation separation method, when ion implantation is performed in a state of a bare wafer in which an insulating film such as an oxide film is not formed on the wafer surface, for example, if the implantation angle is 7 degrees, the separation is performed. It was found that the film thickness uniformity of the later transfer layer has a slight inclination in a certain direction, which deteriorates the film thickness uniformity after peeling.

  Further, when a bonded wafer is manufactured by an ion implantation separation method, when an amorphous oxide film layer is formed on the wafer to be implanted and implantation is performed at an implantation angle of 0 degrees, the thickness of the transfer layer after the separation is uniform. It has been found that, in a certain direction, the central part is thick, the outer peripheral part is thin, and has a convex distribution, which may deteriorate the film thickness uniformity after peeling.

  The present invention has been made in view of the above problems, and in the case of producing a bonded wafer by ion implantation to a uniform depth by a batch type ion implanter, the film thickness of the transfer layer obtained after peeling is uniform. An object of the present invention is to provide a method for producing a bonded wafer on which a thin film having a desired film thickness uniformity is formed.

  In order to achieve the above-mentioned object, the present invention comprises a rotating body and a plurality of wafer holders provided on the rotating body and arranged on the substrate, and ions are applied to the plurality of substrates arranged and revolved on the wafer holder. An ion implantation process for forming an ion implantation layer by implanting at least one kind of gas ions of hydrogen ions and rare gas ions from the surface of the bond wafer using a batch type ion implantation machine; and ions of the bond wafer A bonding process in which the implanted surface and the surface of the base wafer are bonded directly or through an insulating film, and a bonded wafer having a thin film on the base wafer is manufactured by peeling the bond wafer with the ion-implanted layer. In the method for manufacturing a bonded wafer having a peeling step, the bond wafer is a silicon single crystal. In the ion implantation step, the ion implantation is performed twice with the same implantation amount in a bare wafer or a silicon single crystal wafer in which an insulating film having a thickness of 1 nm to 100 nm is formed on the surface on the ion implantation side. When the two ion implantations are performed separately, ion implantation is performed in the revolution direction at an ion implantation angle of + X degrees and −X degrees, respectively, and the channeling of ions implanted into the bond wafer is minimized. Provided is a method for manufacturing a bonded wafer, wherein the method is set so that

  Thus, by performing the ion implantation step, channeling can be suppressed to a minimum, the nonuniformity of the depth of each ion implantation can be offset, and the film thickness uniformity of the thin film after peeling can be improved.

At this time, it is preferable that the equivalent implantation amount at the time of each ion implantation is within a range of 40 to 60% of the total implantation amount in the ion implantation step.
By performing each ion implantation with such an ion implantation amount, ions can be implanted to a more uniform depth, and the film thickness uniformity of the bond wafer after peeling can be kept good.

At this time, it is preferable that the plane orientation of the silicon single crystal wafer is {100}, and the ion implantation angle X degree is 7 degrees or more and 8 degrees or less.
As a result, the occurrence of channeling can be minimized in ion implantation.

  The present invention provides a batch type ion implanter that includes a rotating body and a plurality of wafer holders that are provided on the rotating body and that disposes a substrate, and that performs ion implantation on a plurality of substrates that are disposed and revolved on the wafer holder. An ion implantation step of forming an ion implantation layer by implanting at least one kind of gas ions of hydrogen ions and rare gas ions from the surface of the bond wafer; and the surface of the bond wafer and the surface of the base wafer And a bonding step of bonding a bonded wafer having a thin film on the base wafer by peeling the bond wafer with the ion-implanted layer. In the manufacturing method, the bond wafer has a thickness of 1 nm or more and 100 nm on the surface on the ion implantation side. A silicon single crystal wafer having a lower insulating film is formed, and in the ion implantation step, ion implantation is performed twice with the same implantation amount, and the ion implantation angle + X in the revolution direction during the two ion implantations. Provided is a method for manufacturing a bonded wafer, wherein ions are implanted at a degree of −X degrees and −X degrees, respectively, and the ion implantation angle X degrees is set to 1 to 3 degrees.

  By performing the ion implantation process in this way, it is possible to cancel out the unevenness of the depth of each ion implantation and improve the film thickness uniformity of the thin film after peeling.

At this time, it is preferable that the equivalent implantation amount at the time of each ion implantation is within a range of 40 to 60% of the total implantation amount in the ion implantation step.
By performing each ion implantation with such an ion implantation amount, ions can be implanted to a more uniform depth, and the film thickness uniformity of the bond wafer after peeling can be kept good.

At this time, the plane orientation of the silicon single crystal wafer is preferably set to {100}.
By using a silicon single crystal wafer having such a plane orientation, it can be widely applied to the production of silicon semiconductor elements.

  As described above, according to the present invention, it is possible to manufacture a bonded wafer in which the variation in ion implantation depth distribution is improved and the film thickness uniformity of the thin film is drastically improved. The threshold voltage of a device using such a bonded wafer can be stabilized, and the device yield is improved.

The top view of a part of batch type ion implantation apparatus used with the manufacturing method of the bonded wafer of this invention is shown. The side view of a part of batch type ion implantation apparatus used with the manufacturing method of the bonded wafer of this invention is shown. The perspective view of a part of batch type ion implantation apparatus used with the manufacturing method of the bonded wafer of this invention is shown. It is a figure explaining the method of performing ion implantation in the manufacturing method of the bonded wafer of this invention. It is explanatory drawing explaining a cone angle effect. In the bonded wafer manufacturing method, there are a manufacturing flow chart when a bare wafer is used as a bond wafer, and a film thickness distribution when ion implantation angles are set to 0, +7, and -7 degrees. In the manufacturing method of the bonded wafer of this invention, it is the schematic of ion implantation layer depth, and the film thickness distribution of a thin film when a bare wafer is used as a bond wafer and an ion implantation angle is set to +7 and -7 degree. In the method for manufacturing a bonded wafer, there are a manufacturing flow diagram when a bond wafer having an oxide film is used, and a film thickness distribution of a thin film when an ion implantation angle is 0 degree. In the method for manufacturing a bonded wafer, a manufacturing flow chart in the case of using a bond wafer with a 30 nm-thick oxide film and a film thickness distribution of a thin film when an ion implantation angle is set to 0, +3, and +7 degrees. . In the bonded wafer manufacturing method of the present invention, a bond wafer with a 30 nm thick oxide film is used, and a schematic diagram of the ion implantation layer depth when the ion implantation angle is +2, -2 degrees, It is a film thickness distribution.

  In manufacturing a bonded wafer having a thin film by an ion implantation delamination method using a batch type ion implanter, the present inventors are a bare wafer having no amorphous layer or an oxide film thickness. Can be obtained by changing the ion implantation depth with respect to the circumferential direction of rotation of the rotating body due to the cone angle effect of the rotating body of the batch type ion implanter. It was discovered that the film thickness variation of the thin film increases.

  As described above, in the method for manufacturing a bonded wafer using the ion implantation delamination method, one of the factors causing the depth distribution of ion implantation is a cone angle effect.

  As shown in FIG. 2, in the batch type ion implanter 10, the wafer holder 2 is inclined slightly inward from the rotation surface of the rotating body 1 in order to hold the substrate 3. This is because the substrate 3 is pressed against the wafer holder 2 by the centrifugal force generated by the rotation of the rotating body 1, thereby increasing the pressing force between the back surface of the substrate 3 and the wafer holder 2 and increasing the contact area. This is to increase the cooling capacity of the substrate 3. As a result, when the rotating body 1 rotates, a force that presses the substrate 3 against the wafer holder 2 by the centrifugal force acts, and the wafer holder 2 holds the substrate 3.

  However, when the rotation surface of the rotating body 1 and the surface of the substrate 3 are not parallel in this way, even if an ion beam is to be implanted at a constant angle with respect to the substrate 3, the substrate central portion and both ends of the substrate in the beam scanning direction are: A slight deviation occurs in the injection angle in accordance with the rotation of the rotating body. Thereby, the ion implantation depth is deep at the center of the substrate (FIG. 5A) and shallow at both ends of the substrate in the scanning direction (FIGS. 5B and 5C). This phenomenon is called the cone angle effect.

  For this reason, in ion implantation in the ion implantation separation method, the setting angle between the substrate 3 and the ion beam is set to an implantation angle of 0 degrees (α = 0 °) at which the angle between the surface of the substrate 3 and the ion beam is vertical. Thus (FIG. 5A), the ion implantation depth distribution is made relatively uniform so that the implantation angles are substantially shifted at both ends of the substrate 3 in the scanning direction.

  However, even when the ion implantation angle is set to 0 degree as described above and the influence of the cone angle effect is suppressed, another factor that causes variation in the depth distribution of the ion implantation layer is Thin BOX. It can be mentioned that channeling occurs in the production of a type SOI wafer or a directly bonded wafer without an oxide film.

  In the production of a direct bonding wafer without an oxide film or a Thin BOX type SOI wafer having a BOX layer (silicon oxide film layer) thickness of 100 nm or less, the effect of scattering by the oxide film is reduced, and the ion implantation angle is reduced. Channeling occurs with ion implantation set at 0 degrees.

  In the case of a batch type ion implanter, since the angle of the ion beam is perpendicular to the crystal plane in the substrate at the center of the substrate, the effect of channeling is increased and the ion implantation depth is increased. On the other hand, since the implantation angle is generated by the cone angle effect at both ends of the substrate in the scanning direction, the influence of channeling becomes relatively weak and the ion implantation depth becomes shallow. As described above, in the manufacture of a Thin BOX type SOI wafer or a directly bonded wafer without an oxide film, the cone angle effect is particularly emphasized by channeling.

  Further, when producing a bonded wafer by the ion implantation delamination method, as long as the wafer diameter is as small as 150 mm, the deterioration of uniformity of the implantation depth due to the cone angle effect is not so great, and further, the required variation in the SOI layer thickness varies. The standard of was relatively large, so it was not a problem.

  However, when the wafer diameter is increased to 300 mm or more, the ion implantation angle changes by about 1 degree between the wafer central portion and the wafer outer peripheral portion with respect to the rotation direction of the rotating body due to the cone angle effect. The variation will increase. For this reason, the film thickness variation of the thin film of the bonded wafer produced by the ion implantation peeling method will deteriorate. Furthermore, since the required film thickness uniformity is high in a 300 mm wafer, there are cases where the required specifications cannot be satisfied if the wafer is simply manufactured as before. This was an unexpected phenomenon for those skilled in the art.

  When a bonded wafer having a wafer diameter of 300 mm or more is manufactured by the ion implantation separation method, when ion implantation is performed in the state of a bare wafer, for example, when an ion implantation angle is 7 degrees, On the other hand, the ion implantation angle at the outer periphery of the wafer is shifted by about ± 1 degree. Therefore, although the wafer central portion is implanted at 7 degrees, one wafer outer peripheral portion has an implantation angle of 6 degrees and the other wafer outer peripheral portion has 8 degrees.

  In the case of a silicon single crystal wafer having a plane orientation of {100}, it is known that channeling is generally suppressed to a minimum by setting the ion implantation angle to 7 to 8 degrees. Therefore, when the ion implantation angle is 6 degrees, channeling influence is exerted and the ion implantation depth becomes deep. In addition, an effect of changing the ion implantation depth by sin θ with respect to the ion implantation angle θ is added, and the uniformity of the ion implantation depth is further deteriorated. Due to these two effects, the film thickness uniformity of the thin film after peeling on the bare wafer deteriorates, and the film thickness distribution changes in the rotating direction of the rotating body.

  In addition, when a bonded SOI wafer having a wafer diameter of 300 mm or more is manufactured by the ion implantation separation method, if the ion implantation angle is implanted at 0 degree into a wafer with a relatively thin oxide film thickness, the wafer is caused by the cone angle effect. With respect to the center, the implantation angle of the outer peripheral portion of the wafer is shifted by about ± 1 degree. Therefore, although not as much as the bare wafer, channeling occurs, and the thin film after peeling has a convex distribution with a thick central part and a thin outer peripheral part in the rotating direction of the rotating body, and thus a film thickness after peeling. Uniformity deteriorates.

  As described above, when the ion implantation delamination method is performed on a bare wafer or a wafer having a relatively thin oxide film, particularly when the wafer diameter is large, the deviation of the implantation angle due to the cone angle effect is caused. Due to the size and the occurrence of channeling associated therewith, the film thickness uniformity after peeling deteriorates.

  Therefore, the present inventors suppress the influence of the cone angle effect if the influence of the cone angle effect can be offset at the time of ion implantation, even if the wafer diameter is large and there is no amorphous layer such as an oxide film, Or even if the amorphous layer such as an oxide film is thin, it was thought that the uniformity of the thickness of the thin film after peeling could be improved.

  Then, as a method for improving the uniformity of ion implantation depth during ion implantation (thickness uniformity after peeling), the inventors divide ion implantation into a plurality of times and change the direction of each notch. A method was found to offset the in-plane distribution of the ion implantation depth by rotating the wafer by a predetermined angle. In this method, for example, when the ion implantation is divided into two, the in-plane implantation distribution can be made uniform by rotating the notch angle at the latter half of the ion implantation by 180 degrees with respect to the notch angle at the first half of the ion implantation. .

  However, in the case of a batch type ion implanter, in order to rotate the wafer in such a manner, it is necessary to remove the wafer from the wafer holder once or to remove it from the chamber once. Since this transfer operation causes a risk of particles adhering to the wafer, it is necessary to clean the wafer every time it is taken out.

  As a result of further intensive studies to solve such problems, the present inventors divided the ion implantation into two, and determined the ion implantation angle at the time of ion implantation in the first half and the latter half of the ion implantation depth. It has been found that the uniformity of ion implantation depth can be improved and the thickness of the thin film after peeling can be improved by changing the uniformity so as to cancel out, and the present invention has been completed.

  Hereinafter, the present invention will be described in detail as an example of an embodiment with reference to the drawings, but the present invention is not limited thereto.

A first aspect of the present invention is a batch-type ion that includes a rotating body and a plurality of wafer holders that are provided on the rotating body and on which a substrate is disposed, and that ion-implants the plurality of substrates that are disposed on the wafer holder and are revolving. An ion implantation process for forming an ion implantation layer by implanting at least one kind of gas ions of hydrogen ions and rare gas ions from the surface of the bond wafer using an implanter, and an ion-implanted surface and a base of the bond wafer A bonding process including a bonding process of bonding a wafer surface to an insulating film, and a peeling process of manufacturing a bonded wafer having a thin film on the base wafer by peeling the bond wafer with the ion-implanted layer. In the method for manufacturing a bonded wafer,
The bond wafer is a silicon single crystal wafer in which an insulating film having a thickness of 1 nm or more and 100 nm or less is formed on the surface on the ion implantation side,
In the ion implantation step, ion implantation is performed in two equal amounts, and at the time of the two ion implantations, ions are implanted in the revolution direction at ion implantation angles + X degrees and −X degrees, respectively. A method for manufacturing a bonded wafer, wherein an implantation angle X degree is set to 1 degree or more and 3 degrees or less.

As described above, according to the first aspect of the present invention, at least one kind of gas ions, hydrogen ions and rare gas ions, is first implanted from the surface of the bond wafer to form an ion implantation layer (ion implantation step).
If a silicon single crystal wafer having a plane orientation of {100} is used as the bond wafer of the first invention, the bonded wafer produced by the method of the invention can be widely applied to the production of current silicon semiconductor elements. However, in the first aspect of the present invention, the plane orientation of the wafer is not particularly limited, and the first aspect of the present invention can be similarly implemented even when the plane orientation of the wafer is {110} or {111}. it can.

  In the ion implantation, a batch type ion implanter 10 as shown in FIGS. 1 to 3 is used. The batch type ion implanter 10 includes a rotating body 1 and a plurality of wafer holders 2 provided on the rotating body 1 and on which a substrate 3 is arranged, and a plurality of substrates 3 arranged and revolved on the wafer holder 2. Ion implantation.

In the ion implantation process of the first aspect of the present invention, ion implantation is performed twice with an equivalent implantation amount. At this time, ion implantation angles + X degrees ((a) of FIG. 4) and -X degrees ( Ion implantation is performed in FIG. The ion implantation angle X degrees refers to an angle formed by a normal line of the surface center of the substrate 3 and the ion beam.
Thereby, the nonuniformity of the depth of the ion implantation layer by each ion implantation is offset, and the film thickness uniformity of the thin film after peeling is improved. Further, the ion implantation angle X degrees can be easily changed by adjusting the inclination of the rotating body 1. Accordingly, since it is not necessary to remove the substrate 3 from the wafer holder 2, it is not necessary to perform cleaning for reducing particles of the substrate 3 for each batch, and the throughput can be greatly improved. Incidentally, the “equivalent implantation amount” is an implantation amount in which non-uniformity of the depth of the ion implantation layer is offset by dividing the ion implantation into two times, and the effect of improving the film thickness uniformity after peeling is obtained. It means a range and is not limited to two halves.

Further, as described above, the bond wafer is a silicon single crystal wafer in which an insulating film having a thickness of 1 nm or more and 100 nm or less is formed on the surface on the ion implantation side, and the ion implantation angle X degree is 1 degree or more and 3 degrees. By setting as follows, the influence of channeling at the time of ion implantation can be suppressed, and the film thickness uniformity of the thin film after peeling is improved.
On the other hand, when the ion implantation angle X degree is less than 1 degree, the influence of channeling becomes large and the film thickness uniformity of the thin film after peeling is deteriorated. If the ion implantation angle X degree is 3 degrees or less, the influence of channeling is reduced by the insulating film and the ion implantation angle X degree, and the film thickness uniformity after peeling is improved.

Furthermore, in the ion implantation process of the first aspect of the present invention, it is preferable that the equivalent implantation amount at the time of each ion implantation is within a range of 40 to 60% of the total implantation amount. That is, not only the case of 50% and 50%, but also, for example, the first half may be 40% and the second half 60%.
Thereby, the nonuniformity of the depth of the ion implantation layer by each ion implantation can be canceled effectively, and the film thickness uniformity of the thin film after peeling is improved.

Next, in the first invention, the ion-implanted surface of the bond wafer and the surface of the base wafer are bonded together via an insulating film (bonding step).
Normally, the wafers are bonded to each other without using an adhesive or the like by bringing the surfaces of the bond wafer and the base wafer into contact with each other in a clean atmosphere at room temperature.

Next, in the first aspect of the present invention, a bonded wafer having a thin film on the base wafer is manufactured by peeling the bond wafer with an ion implantation layer (peeling step).
For example, if heat treatment is performed at a temperature of about 500 ° C. or higher in an inert gas atmosphere, the bond wafer can be peeled off by the ion implantation layer. In addition, by performing plasma treatment on the bonding surface in advance, it is possible to perform peeling by applying an external force without performing heat treatment (or after performing heat treatment at a temperature at which peeling does not occur).

Next, the second aspect of the present invention includes a rotating body and a plurality of wafer holders provided on the rotating body and arranged on the substrate, and ion implantation is performed on the plurality of substrates arranged and revolved on the wafer holder. Using a batch type ion implanter, an ion implantation process for forming an ion implantation layer by implanting at least one kind of gas ions of hydrogen ions and rare gas ions from the surface of the bond wafer, and ion implantation of the bond wafer. A bonding process in which the surface and the surface of the base wafer are bonded directly or through an insulating film, and peeling to produce a bonded wafer having a thin film on the base wafer by peeling the bond wafer with the ion implantation layer. In a method for manufacturing a bonded wafer having a process,
The bond wafer is a bare wafer made of a silicon single crystal, or a silicon single crystal wafer in which an insulating film having a thickness of 1 nm or more and 100 nm or less is formed on the surface on the ion implantation side,
In the ion implantation step, ion implantation is performed in two equal amounts, and at the time of the two ion implantations, ions are implanted in the revolution direction at ion implantation angles + X degrees and −X degrees, respectively. A method for producing a bonded wafer, wherein an implantation angle X degrees is set so that channeling of ions implanted into the bond wafer is minimized.

As described above, in the second aspect of the present invention, at least one kind of gas ion of hydrogen ion and rare gas ion is first ion-implanted from the surface of the bond wafer to form an ion implantation layer (ion implantation step).
If the bond wafer of the second aspect of the present invention is a silicon single crystal wafer having a {100} plane orientation, the bonded wafer produced by the method of the second aspect of the present invention can be widely used for the production of current silicon semiconductor elements. Although it can be applied, even in the second aspect of the present invention, as in the first aspect of the present invention, the plane orientation of the wafer is not particularly limited, and even when the plane orientation of the wafer is {110} or {111}, The second present invention can be applied.

  The ion implantation process of the second invention can be performed in the same manner as the ion implantation of the first invention, but in the second invention, ions implanted at a bond wafer with an ion implantation angle of X degrees. Set to minimize channeling of When the ion implantation angle X degree is small, if there is no insulating film on the surface of the bond wafer, the influence of channeling becomes large, and the uniformity of the thin film after peeling is deteriorated. Therefore, in order to avoid the influence of channeling, the uniformity of the thin film after peeling is improved by appropriately increasing the ion implantation angle X degree.

The ion implantation angle X degree in the second aspect of the present invention is preferably 7 degrees or more and 8 degrees or less.
As a result, in the second aspect of the present invention, even when a bare wafer made of silicon single crystal is used as a bond wafer, the influence of channeling can be sufficiently suppressed during ion implantation, and the uniformity of the thin film after peeling is good. Can be.

  In the second aspect of the present invention, the bond wafer is a bare wafer made of silicon single crystal or a silicon single crystal wafer in which a thin insulating film having a thickness of 1 nm to 100 nm is formed on the surface on the ion implantation side. By setting the ion implantation angle X degrees so that channeling of ions implanted into the bond wafer is minimized, the influence of channeling upon ion implantation can be suppressed, and the film thickness uniformity after peeling. Will improve.

In the ion implantation process of the second aspect of the present invention, it is preferable that the equivalent implantation amount at the time of each ion implantation is within a range of 40 to 60% of the total implantation amount.
Thereby, the nonuniformity of the depth of the ion implantation layer by each ion implantation can be canceled effectively, and the film thickness uniformity of the thin film after peeling is improved.

Next, in the second aspect of the present invention, the ion-implanted surface of the bond wafer and the surface of the base wafer are bonded directly or via an insulating film (bonding step).
Normally, the wafers are bonded to each other without using an adhesive or the like by bringing the surfaces of the bond wafer and the base wafer into contact with each other in a clean atmosphere at room temperature.

Next, in the second aspect of the present invention, a bonded wafer having a thin film on the base wafer is manufactured by peeling the bond wafer with an ion implantation layer (peeling step).
For example, if heat treatment is performed at a temperature of about 500 ° C. or higher in an inert gas atmosphere, the bond wafer can be peeled off by the ion implantation layer. In addition, by performing plasma treatment on the bonding surface in advance, it is possible to perform peeling by applying an external force without performing heat treatment (or after performing heat treatment at a temperature at which peeling does not occur).

Hereinafter, the present invention will be described in further detail.
The ion implantation angle at which ion channeling is minimized was investigated as follows. First, a case will be described in which ions are implanted into a bare wafer (no off-angle) having a plane orientation of {100} by which an insulating layer such as an oxide film is not formed on the surface as a bond wafer by an ion implantation separation method. As shown in FIG. 6A, in the production of a bonded wafer using a bare wafer, for example, hydrogen ions are implanted into a bare wafer 5 having a diameter of 300 mm (FIG. 6A) with an acceleration energy of 50 keV. Then, the ion implantation layer 7 is formed (FIG. 6B). Thereafter, the ion-implanted bare wafer 5 and the base wafer 4 with the oxide film 6 (FIG. 6C) are bonded together (FIG. 6D), and then the bare wafer 5 in the ion-implanted layer 7 is bonded. Is peeled off ((e) of FIG. 6).

  In the production of the bonded wafer using the bare wafer, when the ion implantation into the bare wafer 5 (FIG. 6B) is performed, the ion implantation angle is set to 0 degree. When peeling is performed, the film thickness variation of the thin film of the bonded wafer obtained is such that the cone angle effect is added to the influence of channeling, and the PV (maximum value-minimum value) of the film thickness distribution is a large value of 8.9 nm. ((B) of FIG. 6).

  On the other hand, when ion implantation is performed with an ion implantation angle of 7 degrees, the film thickness variation (P-V) is 2.3 nm, with the notch down and from the lower left to the upper right along the rotation direction of the rotating body. Thus, a tendency to increase the film thickness is obtained ((C) in FIG. 6). In addition, when ion implantation is performed with an ion implantation angle of −7 degrees, the film thickness variation (PV) is 2.4 nm, and the film thickness tends to decrease from the lower left to the upper right with the notch down. Is obtained ((D) of FIG. 6). Thus, when the ion implantation angle is ± 7 degrees, the influence of channeling can be suppressed, but the film thickness variation due to the cone angle effect increases. In addition, when ion implantation is performed with an ion implantation angle of −7 degrees, the film thickness distribution (P−V) is almost the same as the ion implantation angle of +7 degrees, and the direction is opposite. Become. When the ion implantation angle is ± 8 degrees, the same result as ± 7 degrees is obtained.

  As described above, it can be seen that channeling can be minimized by setting the ion implantation angle to 7 to 8 degrees with respect to the wafer.

  Therefore, as shown in FIG. 7, about half of the total ion implantation amount is implanted at an implantation angle of 7 degrees at which channeling does not occur ((a) of FIG. 7), and then the remaining half implantation amount is Injection is performed at −7 degrees, which is opposite to the injection angle in the first half ((b) of FIG. 7). In this way, the ion implantation is performed twice with the same implantation amount, and at this time, the ion implantation angle is + X degrees and −X degrees in the revolution direction, so that the depth of the ion implantation layer 7 is increased. Has a peak at the average of the ion implantation depths of the first half and the second half ((c) of FIG. 7), and peeling of the bond wafer occurs at that position. When peeling is performed in this manner, the film thickness variation (P-V) of the wafer becomes 1.7 nm, and the film thickness variation can be improved ((A) in FIG. 7).

  Some wafers have an off-angle with respect to the crystal orientation. In this case, the ion implantation angle may be set in consideration of the off-angle. As described above, channeling can be minimized by setting the ion implantation angle to 7 to 8 degrees for a wafer having a plane orientation of {100}, but when the plane orientation is {110} or {111}. Similarly, channeling can be minimized by setting the ion implantation angle to 7 to 8 degrees.

  Next, as shown in FIGS. 8 and 9, consider the case where ions are implanted into a wafer with a thin oxide film by an ion implantation separation method. 8A, for example, hydrogen ions are applied to a 300 mm bond wafer 3 (FIG. 8A) with an oxide film 6 of 30 nm at an acceleration energy of 50 keV and an ion implantation angle of 0 degree. Ion implantation is performed (FIG. 8B). Thereafter, the bond wafer 3 having the ion implantation layer 7 and having the oxide film 6 and the base wafer 4 (FIG. 8C) are bonded together (FIG. 8D). The wafer is peeled off ((e) in FIG. 8).

  At this time, the film thickness variation (P-V) of the bonded wafer obtained is 1.6 nm, and the film thickness distribution is thick at the center, with the notch down, along the rotation direction of the rotating body, The tendency is that the upper right film thickness is thin and has a convex distribution ((B) in FIG. 8). This is because although the oxide film 6 that can suppress channeling is formed, the oxide film 6 is thin, so that the influence of channeling remains and the cone angle effect appears strongly. When the 200 nm-thick oxide film 6 is formed, the influence of channeling is eliminated, so that the film thickness variation (PV) is 1.0 nm ((C) in FIG. 8).

  Further, in FIG. 9A, for example, hydrogen ions are applied to the bond wafer 3 having a diameter of 300 mm with the oxide film 6 having a thickness of 30 nm (FIG. 9A) with an acceleration energy of 50 keV and ions. Ions are implanted at an implantation angle of 3 degrees (FIG. 9B). Thereafter, the bond wafer 3 having the ion implantation layer 7 and having the oxide film 6 and the base wafer 4 (FIG. 9C) are bonded together (FIG. 9D). The wafer 3 is peeled off ((e) in FIG. 9).

  At this time, although the influence of channeling is reduced by the action of both the oxide film 6 and the ion implantation angle, the film thickness distribution is inclined in one direction due to the influence of the ion implantation angle, and the film thickness variation (P-V ) Becomes 1.6 nm ((C) of FIG. 9) equivalent to 0 degree implantation ((B) of FIG. 9). Furthermore, when the ion implantation angle is increased to 7 degrees, the influence of channeling is eliminated, but the film thickness distribution is a distribution that is inclined more in one direction than in the case of 3 degree implantation, and the film thickness variation (PV) is It increases to 2.4 nm ((D) in FIG. 9).

  Next, as shown in FIG. 10A, hydrogen ions are channeled to a 300 mm diameter bonded wafer 3 with an oxide film 6 having a thickness of 30 nm at an acceleration energy of 50 keV and an ion implantation angle of +2 degrees. When implantation is performed with a reduced influence and separation is performed by the ion implantation separation method, the variation in the film thickness of the bonded wafer obtained is the same as in the case of the implantation angle +3 degrees. It becomes 6 nm, and the tendency that the film thickness increases from the lower left to the upper right along the rotation direction of the rotating body with the notch down is obtained.

  On the other hand, as shown in FIG. 10B, hydrogen ions are implanted into a 300 mm diameter bond wafer with an oxide film having a thickness of 30 nm at an acceleration energy of 50 keV and an ion implantation angle of −2 degrees. When peeling is performed by the injection peeling method, the obtained SOI wafer has a film thickness variation (PV) of 1.6 nm, and the film thickness tends to become thinner from the lower left to the upper right with the notch down. That is, compared with the case where the ion implantation angle is +2 degrees, the PV of the film thickness distribution is almost the same, and the direction is opposite.

  Therefore, as shown in FIG. 10 (c), an implantation amount that is half of the total ion implantation amount is implanted at an ion implantation angle of +2 degrees without causing channeling, and then the remaining half implantation amount is implanted in the first half. Inject at -2 degrees, opposite to the angle. By doing so, the implanted ions have a peak at the average depth of the first and second half implantation depths, and separation occurs at that position. When peeling is performed in this manner, the film thickness variation (P-V) of the bonded wafer becomes 1.0 nm, and the film thickness variation can be improved ((A) in FIG. 10).

  As described above, the case where ion implantation is performed on a bond wafer having no off-angle has been described. Of course, depending on the wafer, an off-angle may be attached to the crystal orientation. In this case, in the present invention, an ion implantation angle that minimizes channeling may be set in consideration of an off-angle. In general, the ion implantation angle is set to 0 degrees while the wafer to be ion-implanted is held by the wafer holder, but the angle deviation may occur depending on how the wafer holder and the rotating body are attached. In this case, the ion implantation angle is adjusted in consideration of the angle deviation.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.
(Examples 1-5, Comparative Examples 1-4)
A silicon single crystal wafer (no off-angle) having a diameter of 300 mm and a plane orientation (100) is prepared as a bond wafer and a base wafer, and a bonded SOI wafer is manufactured under the conditions shown in Tables 1 and 2, and the SOI layer after peeling In-plane film thickness variations (PV: maximum value-minimum value) were compared.
Under any of the conditions, the wafers were bonded together at room temperature, the peeling heat treatment was carried out at 500 ° C. for 30 minutes, and the film thickness after peeling was measured using Acumap manufactured by ADE.

  As shown in Tables 1 and 2, in Examples 1 to 5, the results of film thickness variation were good by performing ion implantation twice with the same implantation amount. In particular, in Examples 1 to 3, since the ion implantation was performed with the oxide film attached to the bond wafer and the ion implantation angle of 1 to 3 degrees, the results of the film thickness variation were particularly good. Further, as shown in Examples 2 and 3, each ion implantation amount is within the range of 40 to 60% of the total implantation amount even if the ion implantation amounts of the two divided ion implantations are not completely the same. If it is, it turned out that the result of film thickness variation becomes favorable.

  On the other hand, in Examples 4 and 5, since the ion implantation angle of the two divided ion implantations was 7 degrees, the influence of channeling could be minimized. In Example 4, the state of the bare wafer As a result of the ion implantation, the film thickness variation was worse than in Examples 1 to 3. However, in Example 4, the ion implantation angle was the same, but the film thickness variation was greatly reduced as compared with Comparative Example 3 in which ion implantation was performed without dividing the ion implantation into two. Furthermore, also in Example 5, the film thickness variation was greatly reduced as compared with Comparative Example 4 in which ion implantation was performed once.

  In Comparative Examples 1 to 4, the ion implantation was performed only once instead of being performed twice, so that the result of the film thickness variation was worse than that of Examples 1 to 5 due to the influence of cone angle.

  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 ... Rotating body, 2 ... Wafer holder, 3 ... Bond wafer (substrate), 4 ... Base wafer, 5 ... Bare wafer, 6 ... Oxide film, 7 ... Ion implantation layer, 10 ... Batch type ion implantation machine.

Claims (4)

A batch type ion implanter comprising: a rotating body; and a plurality of wafer holders provided on the rotating body and disposed on the substrate , wherein the wafer is ion-implanted into a plurality of substrates disposed and revolved. Using a batch type ion implanter in which the holder is tilted inward from the rotating surface of the rotating body, ion implantation is performed by ion-implanting at least one kind of hydrogen ion or rare gas ion from the surface of the bond wafer. An ion implantation step of forming a bond wafer, and a bonding step of bonding the ion-implanted surface of the bond wafer and the surface of the base wafer directly or via an insulating film, and peeling the bond wafer with the ion-implanted layer, A method for producing a bonded wafer comprising a peeling step for producing a bonded wafer having a thin film on the base wafer In,
The bond wafer is a bare wafer made of a silicon single crystal, or a silicon single crystal wafer in which an insulating film having a thickness of 1 nm or more and 100 nm or less is formed on the surface on the ion implantation side,
In the ion implantation step, ion-implantation was carried out in two, the injection amount at the time of each ion implantation, and the range of 40% to 60% of the total injection amount in the ion implantation step, the two ion In the implantation, ions are implanted in the revolution direction at an ion implantation angle of + X degrees and −X degrees, respectively, and the ion implantation angle X degrees is set so that channeling of ions implanted into the bond wafer is minimized. A method for manufacturing a bonded wafer. The plane orientation of the silicon single crystal wafer and {100}, A method of producing a bonded wafer according to claim 1, characterized in that the following the ion implantation angle X of the 7 degrees 8 degrees. A batch type ion implanter comprising: a rotating body; and a plurality of wafer holders provided on the rotating body and disposed on the substrate , wherein the wafer is ion-implanted into a plurality of substrates disposed and revolved. Using a batch type ion implanter in which the holder is tilted inward from the rotating surface of the rotating body, ion implantation is performed by ion-implanting at least one kind of hydrogen ion or rare gas ion from the surface of the bond wafer. Forming an ion implantation process, a bonding process for bonding the ion-implanted surface of the bond wafer and the surface of the base wafer through an insulating film, and peeling the bond wafer with the ion-implanted layer, In the manufacturing method of a bonded wafer having a peeling process for producing a bonded wafer having a thin film on the wafer,
The bond wafer is a silicon single crystal wafer in which an insulating film having a thickness of 1 nm or more and 100 nm or less is formed on the surface on the ion implantation side,
In the ion implantation step, ion-implantation was carried out in two, the injection amount at the time of each ion implantation, and the range of 40% to 60% of the total injection amount in the ion implantation step, the two ion A method for manufacturing a bonded wafer, wherein ions are implanted in the revolution direction at an ion implantation angle of + X degrees and -X degrees, respectively, and the ion implantation angle X degrees is set to 1 to 3 degrees. The method for producing a bonded wafer according to claim 3 , wherein the plane orientation of the silicon single crystal wafer is {100}.

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