JP6135441B2 - Group III nitride composite substrate and method for manufacturing the same, laminated group III nitride composite substrate, group III nitride semiconductor device and method for manufacturing the same - Google Patents

Description

  The present invention relates to a group III nitride composite substrate and a manufacturing method thereof, a laminated group III nitride composite substrate, a group III nitride semiconductor device, and a manufacturing method thereof.

  Group III nitrides such as GaN are suitably used for semiconductor devices because they have excellent semiconductor properties.

  For example, Japanese Unexamined Patent Application Publication No. 2009-126722 (Patent Document 1) discloses a self-standing group III nitride substrate having a diameter of 25 mm to 160 mm and a thickness of 100 μm to 1000 μm as a semiconductor device substrate, as a specific example. A self-supporting GaN substrate having a diameter of 100 mm and a thickness of 400 μm is disclosed.

  Japanese Patent Laid-Open No. 2008-010766 (Patent Document 2) discloses that a substrate for manufacturing a semiconductor device is a heterogeneous substrate having a chemical composition different from that of GaN, and 0.1 μm or more and 100 μm or less bonded to the heterogeneous substrate. A GaN thin film bonded substrate including a GaN thin film having a thickness, as a specific example, a GaN thin film having a diameter of 50.8 mm bonded to a sapphire substrate and a GaN thin film having a thickness of 0.1 μm or 100 μm A laminated substrate is disclosed.

  Japanese Patent Laying-Open No. 2010-182936 (Patent Document 3) discloses, as a semiconductor device substrate, a support substrate, a nitride semiconductor layer, and a bonding layer provided between the support substrate and the nitride semiconductor layer. Disclosed is a composite substrate having a thickness of 5 μm to 220 μm and a diameter of 50.8 mm bonded to a sapphire substrate and a GaN layer formed by pressure bonding between the sapphire substrate and the GaN layer as a specific example. To do.

JP 2009-126722 A JP 2008-010766 A JP 2010-182936 A

  The self-supporting group III nitride substrate disclosed in Japanese Patent Application Laid-Open No. 2009-126722 (Patent Document 1) is very expensive due to high manufacturing cost, and is easily cracked, so that the diameter is increased and the thickness is reduced. There was a problem of difficulty.

  A GaN thin film bonded substrate having a thickness of 0.1 μm disclosed in Japanese Patent Application Laid-Open No. 2008-010766 (Patent Document 2) performs ion implantation to form a GaN thin film. There is a problem that the quality of the crystal of the GaN thin film is lowered by the implantation. Further, from the viewpoint of improving the characteristics of the semiconductor device to be formed, the thickness of the GaN thin film is preferably 10 μm or more. However, when the thickness of the GaN thin film is increased, the depth of the ion implantation from the main surface is increased. There is a problem that the variation becomes large and the variation in the thickness of the GaN thin film of the obtained GaN thin film composite substrate becomes large.

  Further, a GaN thin film bonded substrate having a GaN thin film thickness of 100 μm disclosed in Japanese Patent Application Laid-Open No. 2008-010766 (Patent Document 2) and GaN disclosed in Japanese Patent Application Laid-Open No. 2010-182936 (Patent Document 3). All the composite substrates having a layer thickness of 5 μm to 22 μm have a diameter of about 50.8 mm, and there is a problem that the in-plane distribution of the thickness of the GaN thin film or the GaN layer increases as the diameter increases.

  When a thick group III nitride film is grown on a different type substrate having a different chemical composition and thermal expansion coefficient from a group III nitride substrate such as a sapphire substrate, a large warp occurs, and cracks ( There was a problem that cracking, the same applies hereinafter).

  The present invention solves the above problems, and a group III nitride composite substrate having a group III nitride film having a low cost, a large diameter, a large film thickness, a small film thickness distribution, and a high crystal quality, and a method for producing the same, It is an object of the present invention to provide a laminated group III nitride composite substrate, a group III nitride semiconductor device, and a manufacturing method thereof.

According to an aspect of the present invention, there is provided a group III nitride composite substrate having a diameter of 75 mm or more in which a supporting substrate and a group III nitride film having a thickness of 10 μm or more and 250 μm or less are bonded to each other. the ratio s _t / m _t of the standard deviation s _t of the thickness to the average value m _t of the thickness of the nitride film is 0.001 to 0.2, predetermined surface of the principal plane of the group III nitride layer the ratio s _o / m _o of the standard deviation s _o in absolute value of the off-angle with respect to the mean value m _o of the absolute value of the off angle relative to the plane of orientation is 0.005 to 0.6, III-nitride composite substrate It is.

  According to another aspect of the present invention, a group III nitride composite substrate according to the above aspect, at least one group III nitride layer disposed on a group III nitride film of the group III nitride composite substrate, And a laminated group III nitride composite substrate.

  According to another aspect of the present invention, a group III nitride film in the group III nitride composite substrate according to the above aspect and at least one group III nitride layer disposed on the group III nitride film are provided. And a group III nitride semiconductor device.

According to yet another aspect, the present invention includes at least one group III nitride layer, and an average value m _Lo of an absolute value of an off angle with respect to a plane having a predetermined plane orientation of a main surface of the group III nitride layer. This is a group III nitride semiconductor device in which the ratio s _Lo / m _Lo of the standard deviation s _Lo of the absolute value of the off-angle to is 0.005 or more and 0.6 or less.

  According to still another aspect of the present invention, there is provided a method for producing a group III nitride composite substrate according to the above aspect, wherein a diameter of 75 mm is obtained by laminating a support substrate and a group III nitride film donor substrate. Cutting the group III nitride film donor substrate at a surface located at a predetermined distance from the bonding main surface of the group III nitride film donor substrate of the joint substrate, and the step of forming the above bonded substrate, Forming a group III nitride composite substrate. A method for manufacturing a group III nitride composite substrate.

  According to still another aspect of the present invention, there is provided a method for producing a group III nitride composite substrate according to the above aspect, wherein a diameter of 75 mm is obtained by laminating a support substrate and a group III nitride film donor substrate. By performing at least one of grinding, polishing, and etching from the main surface of the bonding substrate on the side opposite to the bonding main surface of the group III nitride film donor substrate, the group III nitride is formed. Forming a composite substrate, and a method of manufacturing a group III nitride composite substrate.

  According to another aspect of the present invention, there are provided a step of preparing a group III nitride composite substrate according to the above aspect, and at least one layer of group III nitride on the group III nitride film of the group III nitride composite substrate. And a step of growing a layer. A method of manufacturing a group III nitride semiconductor device.

  According to the present invention, a group III nitride composite substrate having a group III nitride film having a low cost, a large diameter, a large film thickness, a small film thickness distribution, and a high crystal quality, a manufacturing method thereof, and a laminated group III nitride composite A substrate, a group III nitride semiconductor device, and a manufacturing method thereof can be provided.

It is a schematic sectional drawing which shows a certain example of the group III nitride composite substrate concerning this invention. It is a schematic plan view which shows the measurement point of the physical-property value in a group III nitride composite substrate. It is a schematic sectional drawing which shows a certain example of the lamination | stacking group III nitride composite substrate concerning this invention. It is a schematic sectional drawing which shows a certain example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows a certain example of the manufacturing method of the group III nitride composite substrate concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the group III nitride composite substrate concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the group III nitride composite substrate concerning this invention. It is a schematic sectional drawing which shows a certain example of the manufacturing method of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows a certain example of the manufacturing method of the group III nitride composite substrate using an ion implantation method. It is a schematic sectional drawing which shows another example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the group III nitride semiconductor device concerning this invention. It is a schematic sectional drawing which shows another example of the manufacturing method of the group III nitride semiconductor device concerning this invention.

<Description of Embodiment of the Present Invention>
A group III nitride composite substrate 1 according to an embodiment of the present invention includes a group III nitride having a diameter of 75 mm or more obtained by laminating a support substrate 11 and a group III nitride film 13 having a thickness of 10 μm or more and 250 μm or less. things complex a substrate 1, the ratio s _t / m _t of the standard deviation s _t of the thickness to the average value m _t of the thickness of the III nitride film 13 is 0.001 to 0.2, III the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off angle of 0.005 or more to the average value m _o of the absolute value of the off angle relative to the plane of the predetermined surface orientation of the principal surface of the nitride layer 13 0 .6 or less. In the group III nitride composite substrate 1 of this embodiment, at least one group III nitride layer 20 having a large diameter and a high crystal quality is grown on the group III nitride film 13 to obtain a group III nitride having high characteristics. The physical semiconductor device 4 can be obtained with high yield.

  In the group III nitride composite substrate 1 according to this embodiment of the present invention, the warpage of the main surface of the group III nitride composite substrate 1 on the group III nitride film 13 side is 50 μm or less, and the entire group III nitride composite substrate 1 is made. The thickness distribution (also referred to as TTV; the same applies hereinafter) can be 30 μm or less. Thereby, the yield of the obtained group III nitride semiconductor device 4 becomes high.

Further, in the group III nitride composite substrate 1 according to the embodiment of the present invention, the ratio of the thermal expansion coefficient α _III-N of the group III nitride film 13 to the thermal expansion coefficient α _S of the support substrate 11 α _III-N / α _S is 0.75 or more and 1.25 or less, and the ratio t _III-N / t _S of the thickness t _III-N of the group III nitride film 13 to the thickness t _S of the support substrate 11 is 0.02 or more and 1 or less. It can be. Thereby, the curvature and crack of the group III nitride layer 20 grown on the group III nitride composite substrate 1 and the group III nitride film 13 can be reduced.

Moreover, in the group III nitride composite substrate 1 of this embodiment of the present invention, the impurity metal atoms in the main surface of the group III nitride film can be 3 × 10 ¹² atoms / cm ² or less. Thereby, the curvature and crack of the group III nitride layer 20 grown on the group III nitride composite substrate 1 and the group III nitride film 13 can be reduced.

  Further, in the group III nitride composite substrate 1 according to the embodiment of the present invention, the root mean square roughness (also referred to as RMS, hereinafter the same) of the main surface of the group III nitride film 13 can be 3 nm or less. . Further, the RMS of the main surface of the support substrate 11 can be 12 nm or less. Thereby, the crystal quality of the group III nitride layer 20 grown on the group III nitride film 13 of the group III nitride composite substrate 1 is improved.

  Moreover, in the group III nitride composite substrate 1 of this embodiment of the present invention, the diameter of the group III nitride composite substrate 1 can be 100 mm or more, and can be 125 mm or more and 300 mm or less. Accordingly, the number of chips of the group III nitride semiconductor device 4 from one group III nitride composite substrate 1 can be increased, and the warp of the group III nitride composite substrate 1 can be reduced. The yield of the semiconductor device 4 can be increased.

Further, in the group III nitride composite substrate 1 of the embodiment of the present invention, the main surface of the group III nitride film 13 has an RMS average value m _III-N of 0.1 nm or more and 2 nm or less. The standard deviation s _III-N is 0.4 nm or less, the main surface of the support substrate has an RMS average value m _S of 0.3 nm to 10 nm, and the RMS standard deviation s _S is 3 nm or less. it can. As a result, a group III nitride layer 20 with high crystal quality is grown on the entire main surface of the group III nitride film 13 of the group III nitride composite substrate 1, and the group III nitride semiconductor device 4 is formed with a high yield. can get.

Further, in the group III nitride composite substrate 1 according to the embodiment of the present invention, the average of the absolute values of the components in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride film The value m _om is 0.3 ° or more and 1.0 ° or less, and the average value m _oa of the absolute values of components in the <1-210> direction of the off angle is 0 ° or more and 0.1 ° or less. it can. Thereby, the characteristic of the obtained group III nitride semiconductor device 4 can be made high.

  The laminated group III nitride composite substrate 2 which is another embodiment of the present invention is disposed on the group III nitride composite substrate 1 of the above embodiment and the group III nitride film 13 of the group III nitride composite substrate 1. And at least one III-nitride layer 20. In the laminated group III nitride composite substrate 2 of the present embodiment, the group III nitride layer 20 disposed on the group III nitride film 13 also has a high crystal quality. Can be manufactured with high yield.

  A group III nitride semiconductor device 4 which is still another embodiment of the present invention is disposed on the group III nitride film 13 and the group III nitride film 13 in the group III nitride composite substrate 1 of the above embodiment. And at least one III-nitride layer 20. The group III nitride semiconductor device 4 of this embodiment includes a group III nitride film 13 having a high crystal quality and a small thickness distribution and a small off-angle distribution, and a group III nitride layer having a high crystal quality disposed thereon. 20 and so on.

The group III nitride semiconductor device 4 which is still another embodiment of the present invention includes at least one group III nitride layer 20, and is off with respect to a plane of a predetermined plane orientation of the main surface of the group III nitride layer 20. The ratio s _Lo / m _Lo of the standard deviation s _Lo of the absolute value of the off angle to the average value m _Lo of the absolute value of the angle is 0.005 or more and 0.6 or less. The group III nitride semiconductor device 4 of the present embodiment includes the group III nitride layer 20 with high crystal quality, and thus has high characteristics.

In the group III nitride semiconductor device 4 according to the embodiment of the present invention, the average of the absolute values of the components in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride layer 20 The value m _Lom is 0.3 ° or more and 1.0 ° or less, and the average value m _Loa of the components of the off-angle <1-210> direction is 0 ° or more and 0.1 ° or less. Can do. Thereby, the group III nitride semiconductor device 4 has high characteristics.

  A method for manufacturing a group III nitride composite substrate 1 according to still another embodiment of the present invention is a method for manufacturing a group III nitride composite substrate 1 according to the above embodiment, including a support substrate 11 and a group III nitride film. A step of forming a bonding substrate 1L having a diameter of 75 mm or more by bonding the donor substrate 13D and a group III nitride film donor substrate 13D of the bonding substrate 1L positioned at a predetermined distance from the bonding main surface. Forming the group III nitride composite substrate 1 by cutting the group III nitride film donor substrate 13D on the surface to be formed. The manufacturing method of the group III nitride composite substrate 1 of the present embodiment efficiently manufactures the group III nitride composite substrate 1 having the group III nitride film 13 having a low cost, a large diameter, a large film thickness, and a high crystal quality. be able to.

  A method for manufacturing a group III nitride composite substrate 1 according to still another embodiment of the present invention is a method for manufacturing a group III nitride composite substrate 1 according to the above embodiment, including a support substrate 11 and a group III nitride film. The bonding substrate 1L is bonded to the donor substrate 13D to form a bonding substrate 1L having a diameter of 75 mm or more, and the bonding substrate 1L is ground from the main surface opposite to the bonding main surface of the group III nitride film donor substrate 13D. And a step of forming group III nitride composite substrate 1 by performing at least one of polishing and etching. The manufacturing method of the group III nitride composite substrate 1 of the present embodiment efficiently manufactures the group III nitride composite substrate 1 having the group III nitride film 13 having a low cost, a large diameter, a large film thickness, and a high crystal quality. be able to.

  A method for manufacturing a group III nitride semiconductor device 4 according to still another embodiment of the present invention includes a step of preparing the group III nitride composite substrate 1 of the above embodiment, and a group III nitride of the group III nitride composite substrate 1. Growing at least one group III nitride layer 20 on the material film 13. The manufacturing method of the group III nitride semiconductor device 4 of this embodiment can manufacture the group III nitride semiconductor device 4 having high characteristics with a high yield.

  In the method of manufacturing the group III nitride semiconductor device 4 according to the embodiment of the present invention, the device supporting substrate 40 is further bonded to the group III nitride layer 20, and the supporting substrate 11 is bonded from the group III nitride composite substrate 1. And a removing step. Thereby, the group III nitride semiconductor device 4 having high mechanical strength and high characteristics supported by the device support substrate 40 can be manufactured with high yield.

<Details of Embodiment of the Present Invention>
[Embodiment 1: Group III nitride composite substrate]
Referring to FIG. 1, a group III nitride composite substrate 1 according to an embodiment of the present invention has a diameter in which a support substrate 11 and a group III nitride film 13 having a thickness of 10 μm to 250 μm are bonded to each other. 0 there a group III nitride composite substrate 1 of the above 75 mm, the ratio s _t / m _t of the standard deviation s _t thickness relative to the average value m _t of the thickness of the III nitride film 13 is 0.001 or more and a .2 or less, the ratio s of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle relative to the plane of the predetermined plane orientation of the principal plane of the group III nitride layer 13 _o / m _o is 0.005 or more and 0.6 or less.

The group III nitride composite substrate 1 of this embodiment has a diameter of 75 mm or more, and the group III nitride film 13 bonded on the support substrate 11 has a thickness of 10 μm or more and 250 μm or less. average 0.2 less 0.001 or ratio s _t / m _t of the standard deviation s _t of the thickness to m _t of the average value of the absolute value of the off angle relative to the plane of the predetermined plane orientation of the main surface by the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off angle for m _o is 0.005 to 0.6, on the III nitride film 13, high crystal quality with large diameter Since at least one group III nitride layer can be grown, a group III nitride semiconductor device having high characteristics can be obtained with high yield.

  In the group III nitride composite substrate 1 of the present embodiment, the bonding form of the support substrate 11 and the group III nitride film 13 is not particularly limited, but in order to increase the bonding strength by bonding, the bonding film 12 is formed. It is preferable to interpose.

(Diameter of group III nitride composite substrate)
The diameter of the group III nitride composite substrate 1 is 75 mm or more, preferably 100 mm or more, more preferably 125 mm or more, and more preferably 150 mm or more from the viewpoint of increasing the number of chips of a semiconductor device from one composite substrate. preferable. Further, the diameter of the group III nitride composite substrate 1 is preferably 300 mm or less, and more preferably 200 mm or less, from the viewpoint of reducing the warpage of the composite substrate and increasing the yield of the semiconductor device.

(Warping of Group III Nitride Composite Substrate on Group III Nitride Film Side)
The warp of the group III nitride composite substrate 1 on the group III nitride film 13 side is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less from the viewpoint of increasing the yield of the semiconductor device to be formed. Here, the warp of the group III nitride composite substrate 1 on the group III nitride film 13 side is the least square plane in which the square of the distance to any point in the main surface of the group III nitride film 13 is minimized. Is the value calculated as the sum of the distance to the point on the main surface that is the most distant from one side and the distance to the point on the main surface that is the most distant from the other side, This is measured by a flatness measuring device, a laser displacement meter, or the like.

(TTV of group III nitride composite substrate)
The TTV (Total Thickness Variation: Total thickness distribution; one of the evaluation indices of flatness. GBIR (Global Backside Ideal Range)) of the group III nitride composite substrate 1 is a semiconductor device to be formed. From the viewpoint of increasing the yield, the thickness is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. Here, the TTV of the group III nitride composite substrate 1 is the group III nitride composite substrate 1 measured in the thickness direction with the main surface of the support substrate 11 which is the back surface of the group III nitride composite substrate 1 as a reference plane. Is the difference between the maximum value and the minimum value of the entire main surface of the group III nitride film 13 that is the surface of the substrate, and the main surface of the support substrate 11 that is the back surface of the group III nitride composite substrate 1 The level difference of the main surface of the group III nitride film 13 which is the surface of the group III nitride composite substrate 1 in a state where the surface is flatly corrected with the reference plane as a reference plane is an optical interference type flatness measurement. It is measured by a device, a laser displacement meter or the like.

(Relationship between support substrate and group III nitride film in group III nitride composite substrate)
The ratio α _III-N / α _S of the thermal expansion coefficient α _III-N of the group III nitride film to the thermal expansion coefficient α _S of the support substrate is determined on the group III nitride composite substrate 1 and its group III nitride film 13. From the viewpoint of reducing warpage and cracks in the group III nitride layer to be grown, it is preferably 0.75 or more and 1.25 or less, more preferably 0.8 or more and 1.2 or less, and further preferably 0.9 or more and 1.1 or less. 0.95 or more and 1.05 or less are particularly preferable.

Further, the ratio t _III-N / t _S of the thickness t _III-N of the group III nitride film to the thickness t _S of the support substrate is determined on the group III nitride composite substrate 1 and the group III nitride film 13. From the viewpoint of reducing warpage and cracks in the group III nitride layer to be grown, 0.02 or more and 1 or less are preferable, 0.06 or more and 0.7 or less are more preferable, 0.15 or more and 0.5 or less are more preferable, 0.2 or more and 0.4 or less are particularly preferable.

(Support substrate)
The support substrate 11 is not particularly limited as long as it can support the group III nitride film 13, but from the viewpoint of reducing the cost by reducing the amount of expensive group III nitride used, A different composition substrate having a different composition is preferable. Furthermore, as described above, the ratio α _III-N / α _S of the thermal expansion coefficient α _III-N of the group III nitride film 13 to the thermal expansion coefficient α _S of the support substrate 11 is 0.75 or more and 1.25 or less. From a preferable viewpoint, the support substrate 11 is made of mullite (3Al ₂ O ₃ .2SiO _{2 to} 2Al ₂ O ₃ .SiO ₂ ), mullite-YSZ (yttria stabilized zirconia), spinel (MgAl ₂ O ₄ ), Al _A sintered body of ₂ O ₃ —SiO ₂ based composite oxide, and a substrate formed of a sintered body obtained by adding an oxide, carbonate or the like to these, a molybdenum (Mo) substrate, a tungsten (W) substrate, or the like is preferable. . Here, the elements contained in the oxide and carbonate are Ca, Mg, Sr, Ba, Al, Sc, Y, Ce, Pr, Si, Ti, Zr, V, Nb, Ta, Cr, Mn, Fe, Preferred examples include Co, Ni, Cu, and Zn. In addition, the support substrate 11 is preferably a conductive support substrate from the viewpoint of manufacturing a vertical device including the group III nitride composite substrate 1, and is preferably a Mo substrate, a W substrate, or the like.

  In addition, RMS (Root Mean Square roughness) of the main surface of the support substrate 11 in the group III nitride composite substrate 1 is grown on the group III nitride film 13 of the group III nitride composite substrate 1. From the viewpoint of improving the crystal quality of the group III nitride layer, it is preferably 12 nm or less, more preferably 6 nm or less, and further preferably 2 nm or less. Here, the RMS of the main surface of the support substrate 11 is polished before the group III nitride film 13 is bonded, or the main surface that is not bonded is polished after the group III nitride film 13 is bonded. Can be adjusted. Here, the RMS of the main surface of the support substrate 11 is a value of a positive square root of an average of the squares of the distances to the points from the reference plane by calculating the reference plane from each point of the main surface of the support substrate 11. , AFM (Atomic Force Microscope), optical interference type roughness meter, stylus type roughness meter and the like.

The main surface of the support substrate 11 preferably has an RMS average value m _S of 0.3 nm or more and 10 nm or less, and an RMS standard deviation s _S of 3 nm or less. With respect to the main surface of the support substrate 11, the average value m _{S of the} RMS is set to 10 nm or less, and the standard deviation s _{S of the} RMS is set to 3 nm or less. Since a high group III nitride layer can be grown, a semiconductor device can be obtained with a high yield. In order to make the RMS average value m _S of the main surface of the support substrate 11 smaller than 0.3 nm, advanced surface polishing is required, and the cost is greatly increased. From these viewpoints, the RMS average value m _S of the main surface of the support substrate 11 is more preferably 0.3 nm or more and 5 nm or less, and further preferably 0.3 nm or more and 2 nm or less. Further, the RMS standard deviation s _S of the main surface of the support substrate 11 is more preferably 2 nm or less, and further preferably 1 nm or less.

Here, the RMS average value m _S and the standard deviation s _S of the main surface of the support substrate 11 are averages calculated from the RMS measured at 13 measurement points on the main surface of the support substrate 11 shown in FIG. Values and standard deviations. The 13 measurement points P on the main surface of the support substrate 11 shown in FIG. 2 are one central point P _C and four directions perpendicular to the central point P _C regardless of the diameter of the support substrate 11. four outer points P _O in the above a and the outer edge to 5mm inwardly, intermediate the positions of each other one of the center point P _C and four of the four points and four outer points located intermediate the outer point P _O It is composed of eight intermediate points P _M that are a combination of the four points. The standard deviation here means the positive square root of unbiased variance.

(Bonding film)
The bonding film 12 is not particularly limited as long as it can bond the support substrate 11 and the group III nitride film 13, but from the viewpoint of high bondability between the support substrate 11 and the group III nitride film 13, SiO ₂ A film, a Si ₃ N ₄ film, a TiO ₂ film, a Ga ₂ O ₃ film, or the like is preferable. In addition, the bonding film 12 is preferably a conductive bonding film from the viewpoint of manufacturing a vertical device including the group III nitride composite substrate 1, for example, a TiO ₂ film, a Ga ₂ O ₃ film, or the like.

(Group III nitride film)
The group III nitride film 13 is a film formed of group III nitride, and is an In _x Al _y Ga _1-xy N film (0 ≦ x, 0 ≦ y, x + y ≦ 1) such as a GaN film or an AlN film. Etc.

  The thickness of the group III nitride film 13 is 10 μm or more, preferably 30 μm or more, more preferably 50 μm or more, and further preferably 100 μm or more from the viewpoint of forming a high-performance group III nitride semiconductor device. Further, the thickness of the group III nitride film 13 is 250 μm or less, preferably 200 μm or less, more preferably 170 μm or less, and further preferably 150 μm or less, from the viewpoint of reducing the amount of expensive group III nitride used.

The ratio s _t / m _t of the standard deviation s _t thickness average thickness for the m _t of the III nitride film 13 is 0.001 to 0.2, 0.001 to 0.15 Is preferable, 0.002 or more and 0.1 or less is more preferable, and 0.01 or more and 0.05 or less are more preferable. To be less than 0.001 the ratio s _t / m _t, since the cutting and polishing to control the highly thickness is required, costs increase. When the ratio s _t / m _t is larger than 0.2, since the uniformity of the film thickness is reduced, the characteristics of the resulting semiconductor device is reduced.

The ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off-angle with respect to a predetermined plane surface of the orientation of the principal plane of the Group III nitride layer 13, 0.005 It is 0.6 or more, 0.005 or more and 0.5 or less are preferred, 0.008 or more and 0.4 or less are more preferred, and 0.05 or more and 0.2 or less are more preferred. In order to make the ratio s _o / m _o smaller than 0.005, cutting and polishing for highly controlling the off-angle are required, which increases costs. The ratio s _o / m _o occurs in larger when group III nitride film 13 portion morphology of group III nitride layer is lowered onto the plane than 0.6, also in-plane distribution of the impurity incorporation increases Therefore, the yield of the obtained semiconductor device is reduced.

  The crystal structure of the group III nitride film 13 is preferably a wurtzite structure from the viewpoint of obtaining a semiconductor device having good characteristics. The predetermined plane orientation that the principal surface of the group III nitride film 13 is closest to is not limited as long as it is suitable for a desired semiconductor device, and is {0001}, {10-10}, {11-20 }, {21-30}, {20-21}, {10-11}, {11-22}, {22-43}, and plane orientations off at 15 ° or less from their respective plane orientations. . Further, the surface orientation of the back surface of each of these surface orientations and the surface orientation turned off at 15 ° or less from the surface orientation of the back surface may be used. That is, the group III nitride film 13 may be any of a polar surface, a nonpolar surface, and a semipolar surface. Further, the main surface of the group III nitride film 13 is preferably the {0001} plane and the back surface thereof from the viewpoint of easily increasing the diameter, and the {10-10} plane from the viewpoint of suppressing the blue shift of the light emitting device obtained. The {20-21} plane and their back are preferred.

Here, the average thickness value m _t of a group III nitride film 13, the thickness of the standard deviation m _t, the standard deviation s _o of the absolute value of the average value m _o of the absolute value, and off-angle of the off-angle, These are the average value and standard deviation calculated from the absolute values of the thickness and off angle measured at 13 measurement points on the main surface of group III nitride film 13 shown in FIG. The three measurement points P on the main surface of the group III nitride film 13 shown in FIG. 2 are based on one center point P _C and its center point P _C regardless of the diameter of the group III nitride film. Four outer points P _O on four directions perpendicular to each other and 5 mm inside from the outer edge, four points located between one central point P _C and four outer points P _O and four outer points It is composed of eight intermediate points P _{M obtained} by combining four points located in the middle of each other. The standard deviation here means the positive square root of unbiased variance.

From the viewpoint of improving the crystal quality of the group III nitride layer grown on the group III nitride film 13 and improving the characteristics of the semiconductor device to be formed, the impurity metal atoms in the main surface of the group III nitride film 13 are 3 ×. 10 ¹² atoms / cm ² or less are preferable, 4 × 10 ¹¹ atoms / cm ² or less are more preferable, and 1 × 10 ¹¹ atoms / cm ² or less are more preferable. In addition, other impurities on the surface of the group III nitride film 13 can improve the crystal quality of the group III nitride layer grown on the group III nitride film 13 and improve the characteristics of the semiconductor device to be formed. The atoms are preferably 2 × 10 ¹⁴ atoms / cm ² or less, and the Si atoms are preferably 9 × 10 ¹³ atoms / cm ² or less.

  The RMS of the main surface of the group III nitride film 13 is preferably 3 nm or less, more preferably 2 nm or less, and more preferably 1 nm or less from the viewpoint of improving the crystal quality of the group III nitride layer grown on the group III nitride film 13. Is more preferable.

The main surface of group III nitride film 13 preferably has an RMS average value m _III-N of 0.1 nm or more and 2 nm or less, and a standard deviation s _{III-N of} RMS of 0.4 nm or less. With respect to the main surface of the group III nitride film 13, the average value m _III-N of the RMS is set to 2 nm or less, and the standard deviation s _III-N of the RMS is set to 0.4 nm or less. Since a group III nitride layer with high crystal quality can be grown on the entire main surface, a semiconductor device can be obtained with a high yield. In order to make the average value m _III-N of the main surface of the group III nitride film 13 smaller than 0.1 nm, advanced surface polishing is required, and the cost is greatly increased. From these viewpoints, the average RMS value m _III-N of the main surface of the group III nitride film 13 is more preferably 0.1 nm or more and 1.5 nm or less, and further preferably 0.2 nm or more and 1 nm or less. Further, the RMS standard deviation s _III-N of the main surface of the group III nitride film 13 is more preferably 0.3 nm or less, and further preferably 0.2 nm or less.

Here, the RMS average value m _III-N and standard deviation s _III-N of the main surface of the group III nitride film 13 are 13 points on the main surface of the group III nitride film 13 shown in FIG. The average value and standard deviation calculated from the RMS measured at the measurement point are as described above. The group III nitride film 13 preferably has a dislocation density of 1 × 10 ⁸ cm ⁻² or less and a carrier concentration of 1 × 10 ¹⁷ cm ⁻³ or more.

The average value m _om of the absolute value of the component in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride film 13 _enhances the characteristics of the obtained group III nitride semiconductor device. In addition, from the viewpoint of reducing the incorporation of carbon impurities and improving the surface morphology, it is preferably 0.3 ° or more and 1.0 ° or less, more preferably 0.4 ° or more and 0.9 ° or less. 5 ° or more and 0.8 ° or less is more preferable. Further, the average value m _oa of the absolute values of the components in the <1-210> direction of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride film 13 is a characteristic of the obtained group III nitride semiconductor device. From the viewpoint of increasing the thickness, 0 ° to 0.1 ° is preferable, 0 ° to 0.09 ° is more preferable, and 0 ° to 0.08 ° is more preferable.

Here, the average absolute value m _omt of the component in the <10-10> direction of the off angle of the main surface of the group III nitride film 13 and the average value of the absolute value of the component in the <1-210> direction of the off angle. m _oa is the absolute value of the component in the <10-10> direction of the off angle measured at the 13 measurement points on the main surface of the group III nitride film 13 shown in FIG. 210 is an average value calculated from absolute values of components in the direction.

[Embodiment 2: Laminated group III nitride composite substrate]
Referring to FIGS. 3, 5, 9, and 17 to 20, the laminated group III nitride composite substrate 2 that is another embodiment of the present invention is the group III nitride composite substrate 1 of the first embodiment. And at least one group III nitride layer 20 disposed on the group III nitride film 13 of the group III nitride composite substrate 1.

  The laminated group III nitride composite substrate 2 of the present embodiment also includes a group III nitride layer 20 disposed by growing on the group III nitride film 13 having a high crystal quality and a small thickness distribution and off-angle distribution. Since the crystal quality is high, a high-performance semiconductor device can be manufactured with high yield.

In the laminated group III nitride composite substrate 2 of the present embodiment, the configuration of the group III nitride layer 20 disposed on the group III nitride film 13 differs depending on the type of group III nitride semiconductor device to be manufactured. . Referring to FIGS. 3 and 4, when a light emitting device is manufactured as group III nitride semiconductor device 4, group III nitride layer 20 includes, for example, n-GaN layer 21, n-In _0.05 Ga _0.95 N layer. 22, an active layer 23 having a multiple quantum well structure, a p-Al _0.09 Ga _0.91 N layer 24, and a p-GaN layer 25.

Referring to FIG. 5, when a HEMT (high electron mobility transistor) which is an example of an electronic device is manufactured as group III nitride semiconductor device 4, group III nitride layer 20 includes, for example, GaN layer 26 and An Al _0.2 Ga _0.8 N layer 27 can be included.

Referring to FIGS. 11, 12, 15, 17, and 19, when fabricating an SBD (Schottky barrier diode), which is another example of an electronic device, as group III nitride semiconductor device 4, group III Nitride layer 20 includes, for example, n ⁺ -GaN layer 201 (carrier concentration is 2 × 10 ¹⁸ cm ⁻³ ) and n ⁻ -GaN layer 202 (carrier concentration is 1 × 10 ¹⁶ cm ⁻³ ), for example. Can do.

Referring to FIGS. 13, 14, 16, 18, and 20, when a PND (pn junction diode) that is still another example of an electronic device is manufactured as group III nitride semiconductor device 4, group III The nitride layer 20 includes, for example, an n ⁺ -GaN layer 203 (carrier concentration is 2 × 10 ¹⁸ cm ⁻³ ), an n ⁻ -GaN layer 204 (carrier concentration is 1 × 10 ¹⁶ cm ⁻³ ), p ^{−, for example.} -GaN layer 205 (Mg concentration is 5 * 10 < ^{17 >} cm ^{< -3 >} ) and p ^<+>- GaN layer 206 (Mg concentration is 1 * 10 < ²⁰ > cm < ^-3 >, for example).

[Embodiment 3: Group III nitride semiconductor device]
Referring to FIGS. 4, 5, 12, and 14 to 16, group III nitride semiconductor device 4, which is still another embodiment of the present invention, is included in the group III nitride composite substrate of embodiment 1. A group III nitride film 13 and at least one group III nitride layer 20 disposed on group III nitride film 13 are included.

  The group III nitride semiconductor device 4 of the present embodiment includes a group III nitride film 13 having a high crystal quality and a small thickness distribution and a small off-angle distribution, and a group III having a high crystal quality disposed by growing on the group III nitride film 13. Since it includes the group nitride layer 20, it has high characteristics.

Referring to FIGS. 4, 5, and 11 to 16, group III nitride semiconductor device 4 of this embodiment includes at least one group III nitride layer 20, and group III nitride layer 20. The ratio s _Lo / m _Lo of the standard deviation s _Lo of the absolute value of the off angle with respect to the average value m _Lo of the absolute value of the off angle with respect to the surface of the predetermined plane orientation of the main surface is 0.005 or more and 0.6 or less. .

Since the group III nitride semiconductor device 4 of the present embodiment is manufactured using the group III nitride composite substrate 1 as described later, the group III nitride film of the group III nitride composite substrate 1 is manufactured. 13 includes a group III nitride layer 20 epitaxially grown (growing a crystal whose crystal orientation is aligned with the crystal of the substrate). Here, the ratio s of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle relative to the plane of the predetermined plane orientation of the principal plane of the Group III nitride layer 13 _o / m _o is 0 Since it is 0.005 or more and 0.6 or less, the standard deviation s _Lo of the absolute value of the off angle with respect to the average value m _Lo of the absolute value of the off angle with respect to the plane of the predetermined plane orientation of the principal surface of the group III nitride layer 20 The ratio s _Lo / m _Lo is 0.005 or more and 0.6 or less. Since the group III nitride semiconductor device 4 of this embodiment includes the group III nitride layer 20 having such a high crystal quality, it has high characteristics.

The group III nitride semiconductor device 4 of the present embodiment includes the standard deviation s of the absolute value of the off angle with respect to the average value m _Lo of the absolute value of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride layer 20. _{The Lo} ratio s _Lo / m _Lo only needs to include the group III nitride layer 20 that is not less than 0.005 and not more than 0.6, and includes the group III nitride film 13 in the group III nitride composite substrate 1. (See FIG. 4, FIG. 5, FIG. 12, and FIG. 14 to FIG. 16) or not (see FIG. 11 and FIG. 13).

Here, the average value m _Lo of the absolute value of the off angle of the group III nitride layer 20 and the standard deviation s _Lo of the absolute value of the off angle are respectively on the main surface of the group III nitride layer 20 shown in FIG. These are the average value and standard deviation calculated from the absolute values of the thickness and off angle measured at 13 measurement points. The three measurement points P on the main surface of the group III nitride layer 20 shown in FIG. 2 are based on one center point P _C and its center point P _C regardless of the diameter of the group III nitride layer. Four outer points P _O on four directions perpendicular to each other and 5 mm inside from the outer edge, four points located between one central point P _C and four outer points P _O and four outer points It is composed of eight intermediate points P _{M obtained} by combining four points located in the middle of each other. The standard deviation here means the positive square root of unbiased variance.

Further, in the group III nitride semiconductor device 4 of the present embodiment, the average value m of the absolute values of the components in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride layer 20 _Lom is preferably 0.3 ° or more and 1.0 ° or less from the viewpoint of improving the characteristics of the group III nitride semiconductor device, reducing the incorporation of carbon impurities, and improving the surface morphology. More preferably, the angle is from 0 ° to 0.9 °, more preferably from 0.5 ° to 0.8 °. Further, the average value m _Loa of the components in the <1-210> direction of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride layer 20 increases the characteristics of the group III nitride semiconductor device. Therefore, 0 ° to 0.1 ° is preferable, 0 ° to 0.09 ° is more preferable, and 0 ° to 0.08 ° is more preferable.

Since the group III nitride semiconductor device 4 of the present embodiment is manufactured using the group III nitride composite substrate 1 as described later, the group III nitride film of the group III nitride composite substrate 1 is manufactured. 13 includes a group III nitride layer 20 epitaxially grown (referred to as growth of a crystal whose crystal orientation is aligned with the crystal of the substrate; the same applies hereinafter). Here, the average value m _om of the absolute values of the components in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the principal surface of the group III nitride film 13 is 0.3 ° or more and 1.0 ° or less. And an average absolute value m _oa of components in the <1-210> direction of the off angle is not less than 0 ° and not more than 0.1 °, a predetermined plane orientation of the main surface of the group III nitride layer 20 The average value m _Lom of the components in the <10-10> direction of the off angle with respect to the surface is 0.3 ° or more and 1.0 ° or less, and the component in the <1-210> direction of the off angle is The absolute value m _Loa is 0 ° or more and 0.1 ° or less. Since the group III nitride semiconductor device 4 of this embodiment includes the group III nitride layer 20 having such a high crystal quality, it has high characteristics.

Here, the average value m _Lom of the components in the <10-10> direction of the off angle of the main surface of the group III nitride layer 20 and the average value of the absolute values of the components in the <1-210> direction of the off angle. m _Loa is the absolute value of the component in the <10-10> direction of the off angle measured at the 13 measurement points on the main surface of the group III nitride layer 20 shown in FIG. 210 is an average value calculated from absolute values of components in the direction.

The configuration of group III nitride semiconductor device 4 differs depending on the type of group III nitride semiconductor device 4. Referring to FIG. 4, group III nitride semiconductor device 4 which is a light emitting device includes, for example, n-GaN layer 21, n-In _0.05 Ga _0.95 N layer 22, active layer 23 having a multiple quantum well structure, p−. A group III nitride layer 20 including an Al _0.09 Ga _0.91 N layer 24 and a p-GaN layer 25, a first electrode 30 disposed on the p-GaN layer 25 side of the group III nitride layer 20, and a group III nitride A second electrode 50 disposed on the n-GaN layer 21 side of the physical layer 20.

Referring to FIG. 5, a group III nitride semiconductor device 4, which is an HEMT (High Electron Mobility Transistor) as an example of an electronic device, includes, for example, a group III including a GaN layer 26 and an Al _0.2 Ga _0.8 N layer 27. a nitride layer 20, the source electrode 60 disposed on the Al _0.2 Ga _0.8 N layer 27 side of the III-nitride layer 20, and the drain electrode 70 and the gate electrode 80, may include.

Referring to FIGS. 11, 12, and 15, group III nitride semiconductor device 4, which is another example of an electronic device, which is an SBD (Schottky barrier diode), includes, for example, n ⁺ -GaN layer 201 (with a carrier concentration). For example, group III nitride layer 20 including 2 × 10 ¹⁸ cm ⁻³ ) and n ⁻ -GaN layer 202 (carrier concentration is, for example, 1 × 10 ¹⁶ cm ⁻³ ), and n ⁻ -GaN of group III nitride layer 20 A first electrode 30 that is a Schottky electrode disposed on the layer 202 side, and a second electrode 50 that is an ohmic electrode disposed on the n ⁺ -GaN layer 201 side of the group III nitride layer 20. it can.

Referring to FIGS. 13, 14, and 16, group III nitride semiconductor device 4 which is a PND (pn junction diode) which is still another example of the electronic device includes, for example, n ⁺ -GaN layer 203 (carrier concentration). 2 × 10 ¹⁸ cm ⁻³ ), n ⁻ -GaN layer 204 (carrier concentration is 1 × 10 ¹⁶ cm ⁻³ ), p ⁻ −GaN layer 205 (Mg concentration is 5 × 10 ¹⁷ cm ⁻³ ), for example. , And p ⁺ -GaN layer 206 (Mg concentration is, for example, 1 × 10 ²⁰ cm ⁻³ ), and p disposed on the p ⁺ -GaN layer 206 side of group III nitride layer 20 -The 1st electrode 30 which is an ohmic electrode, and the 2nd electrode 50 which is an n-ohmic electrode arrange | positioned at the n ^<+>- GaN layer 203 side of the group III nitride layer 20 can be included.

  Referring to FIGS. 4, 5, and 11 to 16, group III nitride semiconductor device 4 has a support substrate 11 and a device for supporting group III nitride layer 20 from the viewpoint of increasing mechanical strength. It is preferable to further include at least one of the support substrates 40. Here, the shape of the device support substrate 40 is not limited to a flat plate shape, and the group III nitride semiconductor device 4 can be formed by supporting the group III nitride film 13 and the group III nitride layer 20. As long as it can take any shape.

  For example, the HEMT that is the group III nitride semiconductor device 4 shown in FIG. 5 includes the group III nitride composite substrate 1 including the support substrate 11. The SBD that is the group III nitride semiconductor device 4 shown in FIG. 15 includes a group III nitride composite substrate 1 including a support substrate 11. A PND that is a group III nitride semiconductor device 4 shown in FIG. 16 includes a group III nitride composite substrate 1 including a support substrate 11. In contrast, the light-emitting device that is the group III nitride semiconductor device 4 shown in FIG. 4 includes a device support substrate 40. The SBD that is the group III nitride semiconductor device 4 shown in FIGS. 11 and 12 includes a device support substrate 40. The PND that is the group III nitride semiconductor device 4 shown in FIGS. 13 and 14 includes a device support substrate 40.

[Embodiment 4: Method for Producing Group III Nitride Composite Substrate]
Referring to FIGS. 6 and 7, the method for manufacturing a group III nitride composite substrate according to still another embodiment of the present invention is a method for manufacturing group III nitride composite substrate 1 of embodiment 1, Step of forming bonded substrates 1L and 1LS having a diameter of 75 mm or more by bonding substrate 11 and group III nitride film donor substrate 13D (FIGS. 6A to 6C, FIG. 7A) And (C)), and by cutting the group III nitride film donor substrate 13D at a surface located at a predetermined distance from the bonding main surface of the group III nitride film donor substrate 13D of the bonding substrates 1L and 1LS. And a step of forming the group III nitride composite substrate 1 (FIG. 6D, FIG. 7D).

  According to the method for manufacturing a group III nitride composite substrate of the present embodiment, the group III nitride composite substrate 1 having a group III nitride film having a low cost, a large diameter, a large film thickness and a high crystal quality is efficiently manufactured. be able to.

  Here, in the step of forming the group III nitride composite substrate 1, the group III nitride film donor substrate 13D is positioned at a predetermined distance from the bonding main surface of the group III nitride film donor substrate 13D when cutting the group III nitride film donor substrate 13D. The predetermined distance on the surface to be processed is determined according to the thickness of the group III nitride film 13 of the group III nitride composite substrate 1 to be manufactured.

  Further, in the step of forming the group III nitride composite substrate 1, after the group III nitride film donor substrate 13D is cut to form the group III nitride film 13, the bonded main surface of the group III nitride film 13 and The thickness of group III nitride film 13 can be reduced by performing at least one of grinding, polishing, and etching from the opposite main surface. In particular, from the viewpoint of reducing the thickness distribution and off-angle distribution of the group III nitride film 13 formed by cutting the group III nitride film donor substrate 13D, the III of the group III nitride composite substrate 1 obtained by cutting is obtained. The main surface of group nitride film 13 is preferably polished. From the viewpoint of reducing the thickness distribution and off-angle distribution of the group II nitride film 13, the polishing method is preferably precise polishing by CMP (chemical mechanical polishing), chemical polishing, or the like.

  From the above viewpoint, the predetermined distance on the surface located at a predetermined distance from the main bonding surface of the group III nitride film donor substrate 13D when the group III nitride film donor substrate 13D is cut is the object of manufacture. It is preferable to set the distance obtained by adding the thickness of the group III nitride film 13 of the group III nitride composite substrate 1 to the thickness of the polishing allowance.

  In the method for manufacturing the group III nitride composite substrate 1 of the present embodiment, the group III nitride is a surface located at a predetermined distance from the bonded main surface of the group III nitride film donor substrate 13D of the bonding substrates 1L and 1LS. The group III nitride film 13 is formed by cutting the film donor substrate 13D, and preferably at least one of grinding, polishing, and etching is performed from the main surface opposite to the bonding main surface of the group III nitride film 13. Thus, the group III nitride composite substrate 1 including the group III nitride film 13 having a desired thickness of 10 μm or more and 250 μm or less is obtained by adjusting the film thickness to be reduced.

  In addition, in the manufacturing method of the group III nitride composite substrate 1 of this embodiment, since the group III nitride film donor substrate is cut in the step of forming the group III nitride composite substrate, workability and efficiency in manufacturing are reduced. From the viewpoint of improving the thickness, the thickness of the group III nitride film donor substrate 13D used is preferably greater than 500 μm, more preferably 1 mm or more, and even more preferably 2 mm or more.

(Junction substrate formation process)
With reference to FIGS. 6A to 6C and FIGS. 7A to 7C, the step of forming the bonding substrates 1L and 1LS is a process of forming the bonding film 12a on the main surface of the support substrate 11. Step (FIGS. 6A and 7A) and sub-step of forming the bonding film 12b on the main surface of the group III nitride film donor substrate 13D (FIGS. 6B and 7B) And a sub-process (FIG. 6C, FIG. 7C) for bonding the bonding film 12a formed on the support substrate 11 and the bonding film 20b formed on the group III nitride film donor substrate 13D. Including.

  6A and 7A, in the sub-process for forming bonding film 12a on the main surface of support substrate 11, bonding film 12a is integrated with bonding film 12b described later to form a bonding film. 12 is formed of the same material as that of the bonding film 12. The method for forming the bonding film 12a is not particularly limited as long as it is suitable for the formation of the bonding film 12a. However, from the viewpoint of efficiently forming the high-quality bonding film 12a, sputtering, CVD (chemical vapor) A phase deposition method, a PLD (pulse laser deposition) method, an MBE (molecular beam growth) method, an EB (electron beam) vapor deposition method and the like are preferable. CVD is particularly preferable because it increases the quality of the bonding film and increases the deposition rate. Here, among CVD, a P-CVD (plasma-chemical vapor deposition) method, a PE-CVD (plasma-assisted chemical vapor deposition) method and the like are more preferable from the viewpoint that a film can be formed at a low temperature and a film forming speed is high. The LP-CVD (reduced pressure-chemical vapor deposition) method and the like are more preferable from the viewpoint of improving the film quality and facilitating mass production.

  Furthermore, in order to improve the bonding strength, annealing can be performed after the bonding films 12a and 12b are formed and before bonding. By this annealing, the bonding films 12a and 12b can be degassed to densify the bonding films 12a and 12b.

Furthermore, the main surface of the bonding film 12a is polished to a mirror surface (for example, a mirror surface having an RMS of 0.3 nm or less) from the viewpoint of increasing the bonding strength between the support substrate 11 and the group III nitride film donor substrate 13D. preferable. The method for polishing the main surface of the bonding film 12a is not particularly limited, and for example, CMP (Chemical Mechanical Polishing) is used. From the viewpoint of increasing the bonding strength, in order to improve the cleanliness of the bonding film, non-abrasive polishing with a liquid that does not contain abrasive grains can be performed after CMP. In order to enhance the effect of removing abrasive grains, non-abrasive polishing with an alkali such as KOH or TMAH (tetramethylammonium hydroxide), or an acid such as HCl, HNO ₃ , or H ₂ SO ₄ can be performed. Further, from the viewpoint of increasing the bonding strength, scrub cleaning using a sponge, a brush, or the like can be performed in order to improve the cleanliness of the bonding film. Two-fluid cleaning, megasonic cleaning, ultrasonic cleaning, and the like can also be suitably performed.

With reference to FIG. 6B and FIG. 7B, in the sub-process of forming the bonding film 12b on the main surface of the group III nitride film donor substrate 13D, the group III nitride film donor substrate 13D This is a donor substrate that provides a group III nitride film 13 by separation in a sub-process. The method for preparing such a group III nitride film donor substrate 13D is not particularly limited, but from the viewpoint of obtaining a group III nitride film donor substrate 13D having good crystallinity, the HVPE (hydride vapor phase epitaxy) method, MOVPE (organic) A vapor phase method such as a metal vapor phase growth method, an MBE (molecular beam growth) method, a sublimation method, a liquid phase method such as a flux method, a high nitrogen pressure solution method, and an ammonothermal method is preferable. The group III nitride film donor substrate 13D prepared in this way is not particularly limited, but from the viewpoint of providing the group III nitride film 13 with good crystallinity, the crystal of the same degree as the group III nitride film 13 to be provided Specifically, the absolute value of the off angle with respect to the average value m _o of the absolute value of the off angle with respect to the surface of the predetermined plane orientation of the main surface of the group III nitride film donor substrate 13D. it preferably has a specific s _o / m _o of the standard deviation s _o of 0.005 to 0.6.

  The material and method for forming the bonding film 12b and the polishing of the main surface thereof are the same as the material and method for forming the bonding film 12a and the polishing of the main surface, respectively.

With reference to FIG. 6C and FIG. 7C, in the sub-step of bonding the bonding film 12a formed on the support substrate 11 and the bonding film 20b formed on the group III nitride film donor substrate 13D, The bonding method is not particularly limited, and the bonding surface is cleaned and bonded as it is, then the direct bonding method in which the temperature is raised to about 600 ° C. to 1200 ° C. and the bonding surface is cleaned and the plasma or ions are washed. Surface activation bonding method in which bonding is performed in a low-temperature atmosphere of room temperature (for example, 25 ° C.) to 400 ° C. after the activation treatment, the bonded surface is washed with a chemical solution and pure water, and then a pressure of about 0.1 MPa to 10 MPa. Preferred is a high-pressure bonding method in which bonding is performed by applying a high pressure, an ultra-high vacuum bonding method in which the bonded surfaces are cleaned with a chemical solution and pure water and then bonded in a high vacuum atmosphere of about 10 ⁻⁶ Pa to 10 ⁻³ Pa, etc. so That. In any of the above bonding methods, the bonding strength can be further increased by raising the temperature to about 600 ° C. to 1200 ° C. after the bonding. In particular, in the surface activated bonding method, the high pressure bonding method, and the ultra-high vacuum bonding method, the effect of increasing the bonding strength by raising the temperature to about 600 ° C. to 1200 ° C. after the bonding is large.

  By the bonding, the bonding film 12a and the bonding film 12b are integrated by bonding to form the bonding film 12, and the support substrate 11 and the group III nitride film donor substrate 13D are bonded with the bonding film 12 interposed therebetween. Thus, the bonded substrates 1L and 1LS are formed.

  As described above, the bonding strength can be increased by activating the bonding surfaces of the bonding films 12a and 12b before bonding. The activation of the bonding surface is not particularly limited, but is preferably performed by plasma treatment, ion treatment, chemical treatment with a chemical solution, cleaning treatment, CMP treatment or the like from the viewpoint of high activation effect.

(Group III nitride composite substrate formation process)
6D and 7D, in the step of forming group III nitride composite substrate 1, from the bonded main surface of group III nitride film donor substrate 13D of bonding substrates 1L and 1LS to the inside The group III nitride film 13 bonded to the support substrate 11 with the bonding film 12 interposed therebetween is cut by cutting the group III nitride film donor substrate 13D at a surface located at a predetermined distance, and the remaining group III nitride Separated into film donor substrate 13Dr, group III nitride composite substrate 1 is formed in which support substrate 11 and group III nitride film 13 are bonded together with bonding film 12 interposed.

  The method for cutting the group III nitride film donor substrate 13D is not particularly limited, and examples thereof include a wire saw, a blade saw, laser processing, electric discharge processing, and water jet.

  When the group III nitride film donor substrate 13D is cut with a wire saw, it is preferable to use a fixed abrasive wire in order to cut the group III nitride film donor substrate 13D with a large diameter flatly. In order to reduce the margin, it is preferable to use a fine wire. In order to reduce the cutting allowance, the loose abrasive method is preferred. Further, when the group III nitride film donor substrate 13D is cut with a wire saw, the wire tension is increased in order to reduce the bending of the wire due to the cutting resistance and increase the accuracy and flatness of the thickness. It is preferable to increase the speed. For this purpose, a highly rigid wire saw device is preferable.

  In order to reduce the cutting resistance and increase the accuracy and flatness of the thickness, it is preferable to vibrate the wire and to vibrate the group III nitride film donor substrate 13D in synchronization therewith. Specifically, when the wire saw is positioned perpendicular to or close to the cutting progress direction of the group III nitride film donor substrate 13D, the group III nitride film donor substrate 13D moves in the cutting progress direction. The group III nitride film donor substrate 13D moves in a direction opposite to the cutting progress direction when the wire saw is positioned at an angle far from the perpendicular to the cutting progress direction of the group III nitride film donor substrate 13D. Thereby, cutting resistance can be reduced.

Note that group III nitrides such as GaN are more brittle and easier to break than sapphire and SiC, and therefore cannot be cut well by the same cutting method as sapphire and SiC. In cutting group III nitride, it is necessary to further reduce the cutting resistance. In order to reduce cutting resistance and increase thickness accuracy and flatness, the viscosity η (Pa · s) of the machining fluid for slicing, the flow rate Q (m ³ / s) of the machining fluid, and the wire linear velocity V (m / S), maximum cutting length L (m), cutting speed P (m / s), and simultaneous cutting number n, expressed as (η × Q × V) / (L × P × n). It is preferable that the resistance coefficient R (N) is in an appropriate range, specifically 4000 or more and 5000 or less.

  The group III nitride composite substrate 1 obtained by cutting can obtain a desired thickness and off-angle and uniformity thereof by polishing the group III nitride film 13 and the main surface of the support substrate 11. it can. Specifically, the fixation of the group III nitride composite substrate 1 to the polishing apparatus at the time of polishing can be performed by suction fixing or fixing by a back pad. Alternatively, the group III nitride composite substrate 1 may be attached to the holding plate and then attached to the polishing apparatus. By mechanical pressurization such as vacuum chuck, air bag pressurization, weight, etc., the tilt can be suppressed and the warp can be corrected and pasted. The group III nitride composite substrate 1 can also be adsorbed and fixed. By uniformly attaching the group III nitride composite substrate 1 to the polishing apparatus, the thickness distribution and the off-angle distribution after polishing can be reduced.

  As described above, in the method for manufacturing a group III nitride composite substrate of the present embodiment, the thickness distribution and the off-angle distribution of the group III nitride film 13 of the group III nitride composite substrate 1 are reduced and the group III nitridation is performed. The main surface of the group III nitride film 13 of the group III nitride composite substrate 1 obtained by cutting from the viewpoint of removing the damaged layer due to the cutting of the material film 13 to maintain high crystal quality and smoothing the main surface. Is preferably polished.

  For this reason, in the manufacturing method of the group III nitride composite substrate of this embodiment, the bonding main group III group nitride film donor substrate 13D which is a surface for cutting the group III nitride film donor substrate 13D of the bonding substrates 1L and 1LS is mainly bonded. The predetermined distance on the surface located at a predetermined distance from the surface is the thickness of the group III nitride film 13 of the group III nitride composite substrate 1 to be manufactured and the thickness of the polishing allowance. It is preferable that the distance is added. Here, the polishing allowance is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more from the viewpoint of reducing the thickness distribution and off-angle distribution and removing the damaged layer. Further, the polishing allowance is preferably 100 μm or less, more preferably 80 μm or less, and further preferably 60 μm or less, from the viewpoint of reducing the material loss of the group III nitride film donor substrate 13D.

  Further, referring to FIGS. 6D and 6B and FIGS. 7D and 7B, the remaining group III nitride film donor substrate 13Dr is repeatedly used by polishing its main surface. Can do.

(Use of III-nitride film donor substrate with support)
Referring to FIGS. 7B to 7D, a group III nitride film donor substrate 5D with a support in which a group III nitride film donor substrate support 15 is bonded to a group III nitride film donor substrate 13D is used. Thus, the group III nitride composite substrate 1 can be manufactured in the same manner as described above. In the group III nitride film donor substrate 5D with the support, since the group III nitride film donor substrate 13D is supported by the group III nitride film donor substrate support 15, the group III nitride film donor substrate 13D cannot stand alone. Even if it becomes as thin as possible, it can be used repeatedly.

In the group III nitride film donor substrate with support 5D, the bonding form of the group III nitride film donor substrate support 15 and the group III nitride film donor substrate 13D is not particularly limited, but the bonding strength by bonding is not limited. In order to increase the thickness, it is preferable to interpose the bonding film 14. The group III nitride film donor substrate support 15 is not particularly limited, but is formed of a material having the same physical properties as the support substrate 11 from the viewpoint of high support strength and prevention of cracks and warpage. It is preferable. The bonding film 14 is not particularly limited, but from the viewpoint of high bondability between the group III nitride film donor substrate support 15 and the group III nitride film donor substrate 13D, the SiO ₂ film, the Si ₃ N ₄ film, the TiO 2 _Two films, a Ga ₂ O ₃ film, and the like are preferable.

[Embodiment 5: Another Method for Producing Group III Nitride Composite Substrate]
Referring to FIG. 8, a method for manufacturing a group III nitride composite substrate according to still another embodiment of the present invention is a method for manufacturing group III nitride composite substrate 1 according to the first embodiment. , A step of forming a bonded substrate 1L having a diameter of 75 mm or more by bonding the group III nitride film donor substrate 13D (FIGS. 8A to 8C), and the group III nitride of the bonded substrate 1L A step of forming the group III nitride composite substrate 1 by performing at least one of grinding, polishing and etching from the main surface opposite to the bonding main surface of the film donor substrate 13D (FIG. 8D); including.

  According to the method for manufacturing a group III nitride composite substrate of the present embodiment, the group III nitride composite substrate 1 having a group III nitride film having a low cost, a large diameter, a large film thickness and a high crystal quality is efficiently manufactured. be able to.

  In the manufacturing method of the group III nitride composite substrate 1 of the present embodiment, by performing at least one of grinding, polishing, and etching from the main surface opposite to the bonded main surface of the group III nitride film donor substrate 13D, The group III nitride composite substrate 1 including the group III nitride film 13 having a desired thickness of 10 μm or more and 250 μm or less is obtained by adjusting the film thickness to be reduced.

  In addition, in the manufacturing method of the group III nitride composite substrate 1 of this embodiment, it grinds from the main surface on the opposite side to the bonding main surface of the group III nitride film donor substrate in the step of forming the group III nitride composite substrate. From the viewpoint of reducing the material loss of the group III nitride film donor substrate 13D because at least one of polishing and etching is performed, the thickness of the group III nitride film donor substrate 13D used is preferably 500 μm or less, and 400 μm. The following is more preferable.

(Junction substrate formation process)
With reference to FIGS. 8A to 8C, the step of forming the bonding substrate 1 </ b> L is performed on the main surface of the support substrate 11 in the same manner as in the method of manufacturing the group III nitride composite substrate of the fourth embodiment. A sub-process for forming 12a (FIG. 8A), a sub-process for forming the bonding film 12b on the main surface of the group III nitride film donor substrate 13D (FIG. 8B), and formation on the support substrate 11. And a sub-process (FIG. 8C) for bonding the bonding film 12a to the bonding film 20b formed on the group III nitride film donor substrate 13D.

  Here, the sub-process for forming the bonding film 12a on the main surface of the support substrate 11 shown in FIG. 8A is a sub-process for forming the bonding film 12a on the main surface of the support substrate 11 shown in FIG. It is the same. The sub-process for forming the bonding film 12b on the main surface of the group III nitride film donor substrate 13D shown in FIG. 8B is performed on the main surface of the group III nitride film donor substrate 13D shown in FIG. This is the same as the sub-process for forming the film 12b. The sub-process for bonding the bonding film 12a formed on the support substrate 11 shown in FIG. 8C and the bonding film 20b formed on the group III nitride film donor substrate 13D is the support substrate 11 shown in FIG. 6C. This is the same as the sub-process in which the bonding film 12a formed in step 1 and the bonding film 20b formed on the group III nitride film donor substrate 13D are bonded together. For this reason, those descriptions are not repeated.

(Group III nitride composite substrate formation process)
Referring to FIG. 8D, in the step of forming group III nitride composite substrate 1, grinding and polishing are performed from the main surface opposite to the bonded main surface of group III nitride film donor substrate 13D of bonding substrate 1L. By performing at least one of etching and etching, the group III nitride film 13 having a reduced thickness is formed from the group III nitride film donor substrate 13D, and the support substrate 11 and the group III nitride film 13 are bonded to each other. Group III nitride composite substrate 1 bonded with film 12 interposed therebetween is formed.

  The method for grinding the group III nitride film donor substrate 13D is not particularly limited, and examples thereof include grinding using a grindstone or abrasive grains. The method for polishing the group III nitride film donor substrate 13D is not particularly limited, and examples thereof include rough polishing such as mechanical polishing, precision polishing such as CMP, and chemical polishing. The method for etching the group III nitride film donor substrate 13D is not particularly limited, and examples include wet etching using a chemical solution and dry etching such as RIE (reactive ion etching).

  Further, from the viewpoint of reducing the thickness distribution and the off-angle distribution of the group III nitride film 13 to be formed, the group III nitride film 13 of the group III nitride composite substrate 1 obtained by at least one of grinding and etching. It is preferable to polish the main surface. From the viewpoint of reducing the thickness distribution and off-angle distribution and removing the damaged layer, the thickness reduction amount due to at least one of grinding, polishing, and etching is preferably 10 μm or more, more preferably 20 μm or more, and 30 μm or more. Further preferred. Further, the amount of reduction in thickness due to at least one of grinding, polishing and etching is preferably 100 μm or less, more preferably 80 μm or less, and more preferably 60 μm or less from the viewpoint of reducing the material loss of the group III nitride film donor substrate 13D. Further preferred.

[Embodiment 6: Method for Producing Group III Nitride Semiconductor Device]
With reference to FIG. 9 and FIGS. 17-20, the manufacturing method of the group III nitride semiconductor device which is further another embodiment of this invention is the process of preparing the group III nitride composite substrate 1 of Embodiment 1. Step of growing at least one group III nitride layer 20 on the group III nitride film 13 of the group III nitride composite substrate 1 (FIG. 9A, FIG. 17A, FIG. 18A) 19 (A) and FIG. 20 (A)). By the group III nitride semiconductor device manufacturing method of this embodiment, a high-performance group III nitride semiconductor device can be manufactured with high yield.

  In the method for manufacturing a group III nitride semiconductor device of the present embodiment, a step of further bonding a device support substrate 40 on the group III nitride layer 20 (FIGS. 9B, 17C, and 18C). And a step of removing the support substrate 11 from the group III nitride composite substrate 1 (FIG. 9C, FIG. 17D1 or D2 and FIG. 18D1 or D2). be able to. By adding these steps, a group III nitride semiconductor device having high mechanical strength and high characteristics supported by the device support substrate 40 can be manufactured with high yield.

  Specifically, the method for producing a group III nitride semiconductor device of the present embodiment can be performed by the following steps.

(Group III nitride layer growth process)
Referring to FIGS. 9A, 17A, 18A, 19A, and 20A, on group III nitride film 13 of group III nitride composite substrate 1, In the step of growing at least one group III nitride layer 20, the method of growing the group III nitride layer 20 includes the MOVPE method and the MBE method from the viewpoint of epitaxially growing the group III nitride layer 20 with high crystal quality. The gas phase method such as HVPE method and sublimation method, and the liquid phase method such as flux method are preferable, and the MOVPE method is particularly preferable.

The group III nitride layer 20 thus obtained is epitaxially grown on the group III nitride film 13, and is the average of the absolute values of the off angles with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride film 13. since the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off angle with respect to the value m _o is 0.005 to 0.6, the predetermined plane orientation of the principal plane of the group III nitride layer 20 the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle relative to the plane becomes 0.005 to 0.6, the crystal quality is high. Further, the average value m _om of the absolute values of the components in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the main surface of the group III nitride film 13 is 0.3 ° or more and 1.0 ° or less. When the average value m _oa of the components of the off-angle <1-210> direction is 0 ° or more and 0.1 ° or less, the main surface of the group III nitride layer 20 has a predetermined plane orientation. The average value m _Lom of the components in the <10-10> direction of the off angle with respect to the surface is 0.3 ° or more and 1.0 ° or less, and the absolute value of the component in the <1-210> direction of the off angle is Since the average value m _Loa is not less than 0 ° and not more than 0.1 °, the group III nitride semiconductor device 4 including the group III nitride layer 20 can have high characteristics.

The configuration of group III nitride layer 20 differs depending on the type of group III nitride semiconductor device 4. Referring to FIG. 9, when group III nitride semiconductor device 4 is a light emitting device, group III nitride layer 20 is formed on group III nitride film 13, for example, n-GaN layer 21, n-In _0.05. A Ga _0.95 N layer 22, an active layer 23 having a multiple quantum well structure, a p-Al _0.09 Ga _0.91 N layer 24, and a p-GaN layer 25 can be grown in this order.

Referring to FIG. 5, when group III nitride semiconductor device 4 is a HEMT (high electron mobility transistor), group III nitride layer 20 is, for example, a GaN layer on group III nitride film 13. 26 and an Al _0.2 Ga _0.8 N layer 27 can be grown in this order.

17 and 19, when group III nitride semiconductor device 4 is an SBD (Schottky barrier diode), group III nitride layer 20 is formed on group III nitride film 13, for example, The n ⁺ -GaN layer 201 (carrier concentration is, for example, 2 × 10 ¹⁸ cm ⁻³ ) and the n ⁻ -GaN layer 202 (carrier concentration is, for example, 1 × 10 ¹⁶ cm ⁻³ ) can be grown in order. .

18 and 20, when group III nitride semiconductor device 4 is a PND (pn junction diode), group II nitride layer 20 is formed on group III nitride film 13, for example, n ⁺ −GaN layer 203 (carrier concentration is 2 × 10 ¹⁸ cm ⁻³ ), n ⁻ −GaN layer 204 (carrier concentration is 1 × 10 ¹⁶ cm ⁻³ ), p ⁻ −GaN layer 205 (Mg concentration is, for example, 5 × 10 ¹⁷ cm ⁻³ ) and p ⁺ -GaN layer 206 (Mg concentration is, for example, 1 × 10 ²⁰ cm ⁻³ ).

  As described above, the laminated group III nitride composite substrate 2 is obtained by growing at least one group III nitride layer 20 on the group III nitride film 13 of the group III nitride composite substrate 1. .

{In the case of manufacturing a group III nitride semiconductor device including a support substrate}
Referring to FIGS. 5, 19, and 20, when manufacturing group III nitride semiconductor device 4 including support substrate 11, from the viewpoint of efficient manufacturing, group III nitride semiconductor device 4 of the present embodiment is used. The manufacturing method includes a step of growing at least one group III nitride layer 20 on the group III nitride film 13 of the group III nitride composite substrate 1 and a step of manufacturing the following electrode. Is preferred. When the group III nitride semiconductor device 4 including the support substrate 11 is manufactured, the device support substrate 40 is not required, and therefore the step of bonding the device support substrate 40 may not be included.

(Electrode formation process)
Referring to FIG. 5, when a HEMT is manufactured as group III nitride semiconductor device 4, for example, source electrode 60, drain electrode 70, and group III nitride layer 20 on the Al _0.2 Ga _0.8 N layer 27 side, and The gate electrodes 80 are formed so as to be separated from each other and the gate electrode 80 is located between the source electrode 60 and the drain electrode 70. Referring to FIG. 19B, when manufacturing SBD as group III nitride semiconductor device 4, for example, insulating film 300 having an opening on the n ⁻ -GaN layer 202 side of group III nitride layer 20 is referred to. Then, a Schottky electrode is formed as the first electrode 30, and an ohmic electrode is formed as the second electrode 50 on the support substrate 11 on the n ⁺ -GaN layer 202 side of the group III nitride layer 20. Referring to FIG. 20B, when manufacturing a PND as the group III nitride semiconductor device 4, for example, an ohmic electrode is used as the first electrode 30 on the p ⁺ -GaN layer 206 side of the group III nitride layer 20. At the same time, an ohmic electrode is formed as the second electrode 50 on the support substrate 11 on the n ⁺ -GaN layer 203 side of the group III nitride layer 20. The method for forming these electrodes is not particularly limited as long as it is suitable for the material of the electrode to be formed, and a vacuum deposition method, a sputtering method, or the like is used. Further, when a sufficiently low contact resistance can be obtained with the support substrate 11 itself, it is not necessary to form an ohmic electrode.

{In case of manufacturing a group III nitride semiconductor device including a device supporting substrate}
Referring to FIGS. 9, 17, and 18, when manufacturing group III nitride semiconductor device 4 including device support substrate 40, device support is further provided on group III nitride layer 20 from the viewpoint of efficient manufacturing. It is preferable to further include a step of bonding the substrate 40 and a step of removing the support substrate 11 from the group III nitride composite substrate 1.

(Device support substrate bonding process)
Referring to FIG. 9B, when a light emitting device is manufactured as the group III nitride semiconductor device 4, the step of further bonding the device support substrate 40 on the group III nitride layer 20 includes a laminated group III nitride composite. The first electrode 30 and the pad electrode 33 are formed on the group III nitride layer 20 of the substrate 2, the pad electrode 43 and the bonding metal film 44 are formed on the device support substrate 40, and the bonding metal film is formed on the pad electrode 33. This is done by pasting 44 together.

  Referring to FIGS. 17B and 17C, when manufacturing an SBD as the group III nitride semiconductor device 4, the step of further bonding the device support substrate 40 on the group III nitride layer 20 is performed by stacking the group III An insulating film 300 having an opening is formed on group III nitride layer 20 of nitride composite substrate 2, and a first electrode is formed on part of insulating film 300 and group III nitride layer 20 in the opening of insulating film 300. A Schottky electrode as 30 is formed, a barrier film 330 is formed on the insulating film 300 on which the first electrode 30 is not formed and the first electrode 30, and a pad electrode 43 and a bonding metal film are formed on the device support substrate 40. 44 is formed, and the bonding metal film 44 is bonded to the barrier film 330.

  Referring to FIGS. 18B and 18C, when manufacturing SBD as group III nitride semiconductor device 4, the step of further bonding device support substrate 40 on group III nitride layer 20 includes group III nitriding. A mesa portion is formed in a part of the physical layer 20, a first electrode 30 is formed on the group III nitride layer 20, and a part of the first electrode 30 and a leg surface of the mesa portion of the group III nitride layer 20 are formed. The insulating film 300 is formed, the barrier film 330 is formed on the first electrode 30 and the insulating film 300, the pad electrode 43 and the bonding metal film 44 are formed on the device support substrate 40, and the bonding metal film is formed on the barrier film 330. This is done by pasting 44 together.

  Through this process, the laminated substrate 3 is obtained. For the device support substrate 40, a Si substrate, a CuW substrate, or the like is used.

(Support substrate removal process)
Referring to FIG. 9C, FIG. 17D1, and FIG. 18D1, the step of removing support substrate 11 from group III nitride composite substrate 1 is performed from layered substrate 3 to group III nitride composite substrate. This is done by removing one support substrate 11. In the group III nitride composite substrate 1, when the bonding film 12 is interposed between the support substrate 11 and the group III nitride film 13, the bonding film 12 can also be removed. Further, referring to FIGS. 17D2 and 18D2, in addition to supporting substrate 11 and bonding film 12, group III nitride film 13 can also be removed. When the group III nitride film 13 of the group III nitride composite substrate 1 is damaged, the group III nitride semiconductor device 4 having high characteristics is removed by removing the damaged group III nitride film 13. Is obtained.

  Here, the method of removing the support substrate 11, the bonding film 12, and / or the group III nitride film 13 is not particularly limited, and grinding, etching, and the like are preferably used. For example, the support substrate 11 formed of a material that has low hardness, strength, and wear resistance and is easily cut can be removed by at least one of grinding and polishing from the viewpoint of reducing manufacturing costs. Further, the support substrate 11 formed of a material that dissolves in a chemical solution such as acid or alkali can be removed by etching with a chemical solution from the viewpoint of low manufacturing cost. From the viewpoint of easy removal of the support substrate 11, the support substrate 11 has a larger number of ceramics or the like than a support substrate formed of a single crystal material such as sapphire, SiC, or a group III nitride (for example, GaN). A support substrate made of a crystalline material is preferred.

(Electrode formation process)
Referring to FIGS. 9D, 17E1 and 18E1, the first surface of group III nitride film 13 exposed by removing support substrate 11 and bonding film 12 from laminated substrate 3 is removed. Two electrodes 50 are formed, and a device support substrate electrode 45 is formed on the device support substrate 40. Alternatively, referring to FIGS. 17E2 and 18E2, group III nitride layer 20 exposed by removing support substrate 11, bonding film 12, and group III nitride film 13 from laminated substrate 3 is used. The second electrode 50 is formed thereon, and the device support substrate electrode 45 is formed on the device support substrate 40. In addition, when the device support substrate 40 itself can provide a sufficiently low contact resistance, it is not necessary to form an ohmic electrode.

(Example A)
1. Production of Group III Nitride Composite Substrate Referring to FIG. 6A, a mullite substrate having a diameter of 75 mm was prepared as a support substrate 11, and diamond abrasive grains and a copper-based surface plate were used for both main surfaces of the support substrate 11. The RMS is mirror-polished to 5 nm or less by rough polishing, intermediate polishing using diamond abrasive grains and tin surface plate, and final polishing using a non-woven polishing pad, and then an SiO ₂ film having a thickness of 800 nm on one of the main surfaces. Is grown by LP-CVD (reduced pressure-chemical vapor deposition) method, and the RMS of the main surface is reduced to 0.3 nm or less by CMP using a slurry having a colloidal silker abrasive having an average particle diameter of 40 nm and a pH of 10. A flattened bonding film 12a having a thickness of 400 nm was formed. In order to remove abrasive grains used in CMP, non-abrasive polishing cleaning with KOH aqueous solution and cleaning with pure water were performed.

Referring to FIG. 6B, a GaN crystal body having a diameter of 75 mm and a thickness of 8 mm is prepared as a group III nitride film donor substrate 13D, and the bonded surface of group III nitride film donor substrate 13D is mechanically polished and subjected to CMP. After the RMS is mirror-finished by 2 nm or less, an SiO ₂ film having a thickness of 800 nm is grown on the bonded surface by LP-CVD (reduced pressure-chemical vapor deposition) method, and a colloidal silica abrasive having an average particle size of 40 nm. A bonding film 12b having a thickness of 500 nm whose main surface was flattened to 0.3 nm or less by RMS was formed by CMP using a slurry containing grains and having a pH of 10. In order to remove the abrasive grains used in CMP, non-abrasive polishing cleaning with an aqueous KOH solution and cleaning with pure water were performed. Here, the group III nitride film donor substrate 13D was grown by HVPE using a GaAs substrate as a base substrate.

  Referring to FIG. 6C, bonding substrate 1L is formed by bonding bonding film 12a and bonding film 12b to bond supporting substrate 11 and group III nitride film 13 with bonding film 12 interposed. Obtained. After bonding, the bonding substrate 1L was annealed by raising the temperature to 800 ° C. in a nitrogen gas atmosphere to increase the bonding strength.

  Referring to FIG. 6D, group III nitride film donor substrate 13D of bonding substrate 1L is cut with a wire saw at a surface located at a depth of 180 μm from the bonding surface with bonding film 12 to the inside. Thus, a group III nitride composite substrate 1 was obtained in which the support substrate 11 and the GaN film as the group III nitride film 13 were bonded together with the bonding film 12 interposed therebetween. The wire used was a fixed abrasive wire electrodeposited with diamond abrasive grains. In order to reduce the cutting resistance and increase the accuracy and flatness of the thickness, the cutting method is a method in which the wire is swung and the group III nitride film donor substrate 13D is vibrated in synchronization therewith. The resistance coefficient of wire saw cutting was 4200N. After cutting, the group III nitride film 13 of the group III nitride composite substrate 1 was subjected to mechanical polishing and CMP. In order to make the thickness and off-angle of the group III nitride film 13 uniform, when attaching the composite substrate to the apparatus by CMP, the substrate shape is preliminarily corrected by vacuum chuck adsorption and then adsorbed and fixed to the apparatus. The method was adopted.

The obtained group III nitride composite substrate 1, the main surface of the ratio s _t / m _t and the Group III nitride films of the standard deviation s _t of the thickness to the average value m _t of the thickness of the III nitride film 13 the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle with respect to the (0001) plane are shown in Table 1. Here, the average value m _t of thickness, standard deviation s _t thickness, average m _o of the absolute value of the off angle, and standard deviation s _t of the absolute value of the off angle, III nitride shown in FIG. 2 On the main surface of the object film 13, one central point P _C , four outer points P _O that are four directions perpendicular to the central point P _C and 5 mm inside the outer edge, and one central point P Measurement of 13 points composed of four points located in the middle of _C and four outer points P _O, and eight middle points P _{M including} four points located in the middle of the four outer points It was calculated from the thickness of the group III nitride film 13 at the point P and the absolute value of the off angle.

2. Production of Group III Nitride Semiconductor Device Referring to FIG. 9A, a group III nitride layer 20 is formed on group III nitride film 13 of group III nitride composite substrate 1 as group III nitride layer 20 by MOVPE. An n-GaN layer 21 having a thickness of 5 μm, an n-In _0.05 Ga _0.95 N layer 22 having a thickness of 50 nm, an In _0.14 Ga _0.86 N well layer having a thickness of 3 nm, and a GaN barrier layer having a thickness of 15 nm are formed on the material film 13. By sequentially growing an active layer 23 having a multi-quantum well structure with three periods, a p-Al _0.09 Ga _0.91 N layer 24 having a thickness of 20 nm, and a p-GaN layer 25 having a thickness of 150 nm, the layer III A group nitride composite substrate 2 was obtained. Thereafter, it was activated by annealing with an RTA (rapid heat treatment apparatus).

  Referring to FIG. 9B, a thickness of 4 nm is formed on the p-GaN layer 25 which is the uppermost layer of the group III nitride layer 20 of the laminated group III nitride composite substrate 2 by EB (electron beam) evaporation. The first electrode 30 was formed by sequentially forming a Ni layer and an Au layer having a thickness of 200 nm and alloying them by annealing. A pad electrode 33 was formed on the first electrode 30 by sequentially forming a Ti layer having a thickness of 200 nm, a Pt layer having a thickness of 100 nm, and an Au layer having a thickness of 1000 nm by an EB vapor deposition method.

  In addition, a CuW substrate is prepared as the device support substrate 40, and a 200 nm thick Ti layer, a 100 nm thick Pt layer, and a 1000 nm thick Au layer are sequentially formed on the device support substrate 40 by EB vapor deposition. Thus, the pad electrode 43 was formed. An AuSn solder film was formed as a bonding metal film 44 on the pad electrode 43.

  Next, the laminated metal substrate 3 was obtained by bonding the bonding metal film 44 to the pad electrode 33.

  Referring to FIG. 9C, the supporting substrate 11 and the bonding film 12 of the group III nitride composite substrate 1 were removed from the laminated substrate 3 by etching using hydrofluoric acid.

  Referring to FIG. 9D, on the exposed group III nitride film 13 from which the support substrate 11 and the bonding film 12 are removed from the laminated substrate 3, a Ti layer having a thickness of 20 nm is formed by EB vapor deposition. A second electrode 50 was formed by sequentially forming and annealing a 200 nm Al layer and a 300 nm thick Au layer. Further, a 20 nm-thick Ti layer and a 300 nm-thick Au layer were sequentially formed on the device support substrate 40 by EB vapor deposition and annealed to form a device support substrate electrode 45. Thus, a group III nitride semiconductor device 4 was obtained.

  About the obtained group III nitride semiconductor device 4, the optical output was measured on the conditions of the injection current 4A using the integrating sphere. The light output of the light emitting element was measured as follows. That is, a predetermined current was injected into the light emitting element placed in the integrating sphere, and the light output was measured by a detector that received the light collected from the light emitting element. Then, a product that conforms to a standard with an optical output of 2 W or more is regarded as a non-defective product, a product that does not conform is regarded as a defective product, and a percentage obtained by dividing the good product by the sum of the surface product and the defective product is defined as a yield. The yields of group III nitride semiconductor devices are summarized in Table 1.

Referring to Table 1, a group III nitride composite substrate having a diameter of 75mm having the III nitride film having a thickness of 150 [mu] m, standard deviation of the thickness to the average value m _t of the thickness of the III nitride film the ratio s _t / m _t of s _t is 0.001 to 0.2, the absolute off-angle with respect to the average value m _o of the absolute value of the off angle with respect to the (0001) plane of the principal plane of the group III nitride layer the ratio s _o / m _o of the standard deviation s _o values were higher yield of the produced group III nitride semiconductor device using the group III nitride composite substrate of 0.005 to 0.6. In Example A1, in order to reduce the thickness distribution and the off-angle distribution, a high degree of control was required during cutting and polishing, and a long time was required for cutting and polishing.

(Example B)
6 and 8, mullite-YSZ substrate (supporting substrate 11 is 70% by mass of mullite and 30% by mass of YSZ with respect to the whole substrate, and 90% by mol of ZrO ₂ with respect to YSZ. ₂ O ₃ is 10 mol%), and the group III nitride composite substrate 1 having diameters of 75 mm, 100 mm, 125 mm, and 150 mm, respectively, as shown in Table 2 with the thickness of the group III nitride film changed. A group III nitride composite substrate 1 and a group III nitride semiconductor device 4 were manufactured in the same manner as in Example A except that the above was manufactured.

In the same way as in Example A, III-a nitride composite substrate 1, III-ratio s _t / m _t and the Group III nitride Standard deviation of thickness s _t to the average value m _t of the thickness of the nitride film 13 by calculating the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle with respect to the (0001) plane of the main surface of the object layer, are summarized in Table 2. Further, in the same manner as in Example A, the yield of the group III nitride semiconductor device 4 was calculated and summarized in Table 2.

Referring to Table 2, a Group III nitride composite substrate having a diameter of 75 mm to 150 mm having a Group III nitride film having a thickness of 10 μm to 250 μm, and the thickness of the Group III nitride film with respect to the average value m _t 0.12 the ratio s _t / m _t of the standard deviation s _t is 0.001 to 0.2 of the average of the absolute value of the off angle with respect to the (0001) plane of the principal plane of the group III nitride layer group III ratio s _o / m _o of the standard deviation s _o of the absolute value of the off angle were made using the group III nitride composite substrate of 0.3 0.005 to 0.6 relative to the value m _o The yield of nitride semiconductor devices was high.

(Example C)
As a semiconductor device substrate, a group III nitride free-standing substrate (hereinafter also referred to as an FS substrate), a group III nitride composite substrate (hereinafter also referred to as a BP substrate) manufactured by an ion implantation method, and Embodiment 4 of the present invention A group III nitride composite substrate (hereinafter also referred to as a BS substrate) prepared by the above was prepared.

  The FS substrate was a substrate having a diameter and thickness shown in Table 3 by cutting and polishing a GaN crystal having a predetermined diameter with a wire saw.

  In the BP substrate, as shown in FIG. 10B, hydrogen ions are implanted into a GaN crystal body having a predetermined diameter, which is a group III nitride film donor substrate 13D, at a predetermined depth from the main surface to the inside. Then, after forming the ion implantation region 13i, as shown in FIG. 10C, the support substrate 11 and the group III nitride film donor substrate 13D are bonded to each other with the bonding film 12 interposed therebetween. 10D, the group III nitride film donor substrate 13D is separated by its ion implantation region 13i by annealing at 850 ° C., as shown in FIG. A substrate having a nitride film thickness was obtained. Here, a mullite substrate was used as the support substrate 11.

  The BS substrate was a substrate having a diameter and group III nitride film thickness shown in Table 3 in the same manner as in Example B, except that a mullite substrate was used as the support substrate.

  A group III nitride composite substrate 1 and a group III nitride semiconductor device 4 were produced in the same manner as in Example B except that the above FS substrate, BP substrate, and BS substrate were used.

In the same way as in Example A, III-a nitride composite substrate 1, III-ratio s _t / m _t and the Group III nitride Standard deviation of thickness s _t to the average value m _t of the thickness of the nitride film 13 by calculating the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle with respect to the (0001) plane of the main surface of the object layer, are summarized in Table 3. Further, in the same manner as in Example A, the yield of the group III nitride semiconductor device 4 was calculated and summarized in Table 3.

  Referring to Table 3, a group III nitride semiconductor device manufactured using an FS substrate having a diameter of 50 mm to 125 mm and a thickness of 200 μm to 500 μm has a large warp and a crack. Both yields were less than 60%.

  In addition, a group III nitride semiconductor device manufactured using a BP substrate having a diameter of 75 mm to 125 mm and a group III nitride film thickness of 0.5 μm is excellent because the group III nitride film has a small thickness. Device characteristics did not appear and yield rate decreased.

  In contrast, the group III nitride semiconductor device fabricated using the BS substrate had a high yield of 65% or more.

(Example D)
The same as Example B, except that an Al ₂ O ₃ —SiO ₂ composite oxide substrate (85% by mass of Al ₂ O _{3 and} 15% by mass of SiO ₂ with respect to the entire substrate) was used as the support substrate. The warpage and TTV of a plurality of group III nitride composite substrates produced in the manner described above were measured and found to be as shown in Table 4. Here, the warpage and TTV of the group III nitride composite substrate were measured by an optical interference type flatness tester.

  Using these group III nitride composite substrates, group III nitride semiconductor devices were fabricated in the same manner as in Example B.

For Group III nitride composite substrate, (0001) major surface of the ratio s _t / m _t and the Group III nitride films of the standard deviation s _t of the thickness to the average m _t of the thickness of the III nitride film surface the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle, and the warp and TTV group III nitride composite substrate are summarized in Table 4 for. Further, in the same manner as in Example A, the yield of the group III nitride semiconductor device 4 was calculated and summarized in Table 4.

  Referring to Table 4, a group III nitride semiconductor device fabricated using a group III nitride composite substrate having a warp on the main surface on the group III nitride film side of 50 μm or less and a TTV of 30 μm or less is The retention rate was high.

(Example E)
Different ratios α _III-N / α _S of the thermal expansion coefficient of the III nitride film to the thermal expansion coefficient of the support substrate alpha _S alpha _III-N, and the III nitride film to the thickness t _S of the support substrate A group III nitride semiconductor device was produced in the same manner as in Example B, except that a plurality of group III nitride composite substrates having different thickness t _III-N ratios t _III-N / t _S were used. Here, in order to change the above ratio, a mullite substrate, a mullite-YSZ substrate, and an Al ₂ O ₃ —SiO ₂ composite oxide substrate having different thicknesses were used as the base substrate.

The thickness t _III III nitride film for the ratio α _III-N / α _S and the thickness t _S of the support substrate of the thermal expansion coefficient alpha _III-N III nitride film to the thermal expansion coefficient alpha _S of the support substrate Table 5 summarizes the _-N ratio t _III-N / t _S , and the yield of group III nitride semiconductor devices.

Referring to Table 5, the ratio α _III-N / α _S of the thermal expansion coefficient α _III-N of the group III nitride film to the thermal expansion coefficient α _S of the support substrate is 0.75 or more and 1.25 or less, III manufactured using a group III nitride composite substrate in which the ratio t _III-N / t _{S of the} group III nitride film thickness t _III-N to the thickness t _S of the support substrate is 0.02 or more and 1 or less The yield of group nitride semiconductor devices was high.

(Example F)
A group III nitride composite substrate and a group III nitride semiconductor device were manufactured in the same manner as in Example B except that the amount of impurity metal atoms on the surface of the group III nitride film was adjusted by adjusting the cleaning conditions. Produced. Table 6 summarizes the diameter of the group III nitride composite substrate, the amount of impurity metal atoms on the surface of the group III nitride film, and the yield of the group III nitride semiconductor device. Here, the amount of impurity metal atoms on the surface of the group III nitride film was measured by a TXRF (total reflection fluorescent X-ray) method. Here, the measurement by the TXRF method was performed using a tungsten (W) radiation source at an incident angle of 0.05 °.

Referring to Table 6, the steps of a group III nitride semiconductor device manufactured using a group III nitride composite substrate in which impurity metal atoms on the main surface of the group III nitride film are 3 × 10 ¹² atoms / cm ² or less are used. The retention rate was high.

(Example G)
A mullite substrate is used as a supporting substrate, a group III nitride film donor substrate is doped with O and Si, a dislocation density is 4 × 10 ⁶ cm ⁻² and a carrier concentration is 2 × 10 ¹⁸ cm ⁻³ . A group III nitride composite substrate and a group III nitride semiconductor device were produced in the same manner as in Example B except that a uniform GaN crystal without a dislocation concentration region was used. Here, the maximum RMS of the group III nitride film and the main surface of the support substrate was adjusted by adjusting the polishing conditions.

  Table 7 summarizes the maximum RMS of the main surface of the group III nitride film and the supporting substrate in the group III nitride composite substrate, and the yield of the group III nitride semiconductor device.

  Referring to Table 7, a group III nitride produced using a group III nitride composite substrate in which the RMS of the main surface of the group III nitride film is 3 nm or less and the RMS of the main surface of the support substrate is 12 nm or less The yield rate of semiconductor devices was high.

(Example H)
Using an Al ₂ O ₃ —SiO ₂ composite oxide substrate (82% by mass of Al ₂ O _{3 and} 18% by mass of SiO _{2 based on the} entire substrate) as a supporting substrate, and as a group III nitride film donor substrate, A group III nitride composite substrate was fabricated in the same manner as in Example B, except that a semi-insulating GaN crystal having Fe added as a dopant and having a specific resistance of 1 × 10 ⁷ Ωcm was used. Here, by adjusting the polishing conditions, the RMS value m _III-N and standard deviation s _III-N of the main surface of the group III nitride film of the group III nitride composite substrate, and the main surface of the support substrate The RMS average value m _S and the standard deviation s _S were adjusted.

  Further, referring to FIG. 5, a HEMT was manufactured as group III nitride semiconductor device 4 as follows.

First, a GaN layer 26 having a thickness of 1.5 μm and an Al _0.2 Ga _0.8 N having a thickness of 30 nm are formed on the group III nitride film 13 of the group III nitride composite substrate 1 as a group III nitride layer 20 by MOVPE. The layered group III nitride composite substrate 2 was obtained by epitaxially growing the layer 27 in order.

Next, the source electrode 60 and the drain electrode 70 were produced on the Al _0.2 Ga _0.8 N layer 27 by photolithography, EB vapor deposition, and lift-off. On these electrodes, a Ti layer having a thickness of 20 nm, an Al layer having a thickness of 100 nm, a Ti layer having a thickness of 20 nm, and an Au layer having a thickness of 300 nm are sequentially formed, lifted off, and then annealed at 600 ° C. for 1 minute. Was alloyed.

  Next, the gate electrode 80 was produced by the same process as the production of the source electrode 60 and the drain electrode 70. In manufacturing the gate electrode 80, a Ni layer having a thickness of 50 nm and an Au layer having a thickness of 500 nm were sequentially formed. The gate length was 2 μm.

The HEMT, which is the group III nitride semiconductor device 4 thus obtained, has a GaN layer 26 as at least one group III nitride layer 20 on the group III nitride film 13 of the group III nitride composite substrate 1. And the Al _0.2 Ga _0.8 N layer 27, the source electrode 60, the drain electrode 70, and the gate electrode 80 are separated from each other on the Al _0.2 Ga _0.8 N layer 27, and the gate electrode 80 is separated from the source electrode 60. It was arrange | positioned so that it might be located between the drain electrodes 70.

The resulting gate current density of the HEMT was examined. Specifically, when a gate voltage of 5 V is applied, a leaked gate current density conforming to a standard of 1 × 10 ⁻⁶ A / cm ² or less is regarded as a non-defective product, and a non-conforming product is regarded as a defective product. The percentage obtained by dividing the non-defective product by the total of the non-defective product and the defective product was taken as the yield rate.

RMS average value m _III-N and standard deviation s _III-N of the main surface of the group III nitride film in the group III nitride composite substrate, and RMS average value m _S and standard deviation s _S of the main surface of the support substrate Table 8 summarizes the yields of group III nitride semiconductor devices.

Referring to Table 8, the main surface of the group III nitride film has an RMS average value m _III-N of 0.1 nm to 2 nm and an RMS standard deviation s _III-N of 0.4 nm or less. In addition, the main surface of the support substrate is a group III nitride composite substrate manufactured using a group III nitride composite substrate having an RMS average value m _S of 0.3 nm to 10 nm and an RMS standard deviation s _S of 3 nm or less. The yield of group nitride semiconductor devices was high.

Example I
1. Production of Group III Nitride Composite Substrate Referring to FIGS. 8A to 8C, an Al ₂ O ₃ —SiO ₂ composite oxide substrate having a diameter of 100 mm as support substrate 11 (Al ₂ O ₃ relative to the entire substrate). There it was prepared SiO ₂ is 12 wt%) at 88 wt%, the III nitride film donor substrate 13D thickness in diameter 100mm as is was prepared GaN crystal substrate of 400 [mu] m, the support substrate 11 and the group III After a SiO ₂ film having a thickness of 500 nm is grown on each main surface of the nitride film donor substrate 13D by PE-CVD, CMP is performed using a slurry having an average particle diameter of 20 nm and containing colloidal silica having a pH of 9. Bonding films 12a and 12b having a thickness of 250 nm, whose main surface is flattened to have an RMS roughness of 0.15 nm or less, and pure water and PVA (polyvinyl chloride) are washed with pure water. It was subjected to scrub cleaning using an alcohol) sponge, except got bonded substrate 1L analogously to Example A.

  Referring to FIG. 8D, grinding and polishing were performed from the main surface opposite to the bonded main surface of group III nitride film donor substrate 13D of bonding substrate 1L. In grinding, a vitrified grindstone including diamond abrasive grains having an average particle diameter of 25 μm to 35 μm was used. In the polishing, mechanical polishing was performed stepwise using slurries containing diamond abrasive grains having average particle diameters of 3 μm, 2 μm, and 0.25 μm, respectively. In order to reduce the thickness distribution and the off-angle distribution, the polishing was performed by sticking to the holding plate in a state where the warpage of the substrate was corrected by mechanical pressure in advance. After the polishing, a dry etching process using a chlorine gas plasma generated by an ICP-RIE (inductively coupled plasma-reactive ion etching) method was performed. In Example I8, rough polishing was performed using diamond abrasive grains having an average particle diameter of 9 μm instead of the above grinding. Thus, a group III nitride composite substrate 1 including a group III nitride film 13 having a thickness of 150 μm was obtained.

2. Production of Group III Nitride Semiconductor Device Referring to FIG. 9, the average particle size is determined by using group III nitride composite substrate 1 in this example and removing support substrate 11 and bonding film 12 from laminated substrate 3. It was carried out by grinding using a vitrified grindstone containing diamond abrasive grains of 35 μm to 45 μm, and in particular for Example I9, it was carried out by polishing using diamond abrasive grains having an average particle diameter of 15 μm, such grinding and / or polishing. A group III nitride semiconductor device 4 was obtained in the same manner as in Example A, except that etching cleaning with hydrofluoric acid was used to remove the residue of the bonding film and the support substrate later.

In the same way as in Example A, III-a nitride composite substrate 1, III-ratio s _t / m _t and the Group III nitride Standard deviation of thickness s _t to the average value m _t of the thickness of the nitride film 13 by calculating the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle with respect to the (0001) plane of the main surface of the object layer, are summarized in Table 9. Further, in the same manner as in Example A, the yield of the group III nitride semiconductor device 4 was calculated and summarized in Table 9.

Referring to Table 9, the ratio s _t / m _t of the standard deviation s _t of the thickness to the average value m _t of the thickness of the III nitride film is 0.001 to 0.2, the Group III nitride the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle is 0.005 to 0.6 with respect to the (0001) plane of the main surface of the object film The yield of group III nitride semiconductor devices fabricated using group III nitride composite substrates was high. In Example I1, in order to reduce the thickness distribution and off-angle distribution, a high degree of control was required during grinding and polishing, and a long time was required for grinding and polishing.

(Example J)
In this example, referring to FIG. 17, an SBD (Schottky barrier diode) which is a group III nitride semiconductor device including a device support substrate 40 is manufactured.

1. Production of Group III Nitride Composite Substrate As in Example A, except for the following points, a mullite substrate used in Example A as a support substrate or a mullite-YSZ substrate used in Example B as a support substrate, and a bonding film A group III nitride composite substrate was fabricated using a GaN crystal as the SiO ₂ film and group III nitride film donor substrate.

In Examples J1 to J4, using a mullite substrate with a diameter of 75 mm as a support substrate and a group III nitride film donor substrate with a diameter of 75 mm, the cutting position by a wire saw when cutting the group III nitride film donor substrate is determined. By changing the thickness, the average thickness of the group III nitride film was set to 100 μm (Example J1), 50 μm (Example J2), 10 μm (Example J3), and 7 μm (Example J4), respectively. In Example J5, a mullite substrate with a diameter of 75 mm as a supporting substrate and a group III nitride film donor substrate with a diameter of 75 mm were used, and the same method as that of the BP substrate in Example C was used. The average thickness of the nitride film was 0.5 μm. In Examples J1 to J5, the main surface of group III nitride film 13 was turned off by 0.50 ° in the [10-10] direction from the (0001) plane. Further, the absolute value m _oa of the component in the [1-210] direction of the main surface of the main surface of the group III nitride film 13 from the (0001) plane was set to 0.1 ° or less. Table 10 summarizes the physical properties of the group III nitride composite substrates of Examples J1 to J5.

  In Examples J6 to J9, a mullite substrate having a diameter of 75 mm as a supporting substrate and a group III nitride film donor substrate having a diameter of 75 mm were used as a group III nitride film donor substrate from the (0001) plane to [10-10]. ] By using GaN crystals having different average values and standard deviations of the absolute value of the off-angle of the main surface in the [10] direction, the [10-10] direction from the (0001) plane of the main surface of the group III nitride film The mean and standard deviation of the absolute values of the off angles are 0.50 ° and 0.20 °, 0.50 ° and 0.40 °, 0.30 ° and 0.10 °, 0.20 ° and The angle was 0.10 °. In addition, the average thickness of the group III nitride film was 100 μm. Table 10 summarizes the physical properties of the Group III nitride composite substrates of Examples J6 to J9.

  In Example J10 and Example J11, the diameter of the support substrate and the group III nitride film donor substrate was 100 mm. In Example J12 to Example J14, the mullite-YSZ substrate used in Example B was used as the support substrate. In Examples J12 and J13, the diameter of the support substrate and the group III nitride film donor substrate was 100 mm. The diameter of the support substrate and the group III nitride film donor substrate was 150 mm. Table 10 summarizes the physical properties of the Group III nitride composite substrates of Examples J10 to J14.

2. Fabrication of Group III Nitride Semiconductor Device Referring to FIG. 17A, a carrier stop layer is formed on group III nitride film 13 of group III nitride composite substrate 1 as group III nitride layer 20 by MOVPE. N ⁺ -GaN layer 201 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of 1 μm, and n ⁻ − having a carrier concentration of 1 × 10 ¹⁶ cm ⁻³ and a thickness of 5 μm. The laminated group III nitride composite substrate 2 was obtained by epitaxially growing the GaN layer 202 in order. Here, the growth temperature of the group III nitride layer 20 was 1050 ° C., TMG (trimethylgallium) and NH ₃ were used as the GaN raw material, and SiH ₄ was used as the Si dopant raw material. The average value and standard deviation of the absolute value of the off-angle with respect to the (0001) plane of the main surface of the obtained group III nitride layer 20 were measured by X-ray diffraction method. The average value and the standard deviation of the absolute value of the off angle with respect to the (0001) plane were the same.

Next, referring to FIG. 17B, an insulating film 300 for a field plate is formed on the n ⁻ -GaN layer 202 which is the uppermost layer of the group III nitride layer 20 of the stacked group III nitride composite substrate 2. A SiN _x film having a thickness of 500 nm was formed by plasma CVD using SiH ₄ and NH ₃ as raw materials. Then heat-treated for 3 minutes in N ₂ 600 ° C. using a RTA (rapid thermal device). Next, using a resist mask formed by photolithography, buffered hydrofluoric acid (50% by mass of HF (hydrofluoric acid) aqueous solution and 40% by mass of NH ₄ F (ammonium fluoride) aqueous solution) is 1: 5. The insulating film 300 having an opening as a field plate was formed by removing the SiN _x film at the resist mask opening by etching for 15 minutes at a volume ratio of 1. Here, the planar shape of each opening of the insulating film 300 After the above etching, the resist was removed using acetone.

Next, a resist mask (not shown) is formed by photolithography, an Ni layer having a thickness of 50 nm and an Au layer having a thickness of 300 nm are formed by EB vapor deposition, and lift-off in acetone is performed. A Schottky electrode patterned as 30 was formed. The planar shape of each Schottky electrode as the first electrode 30 is 1.1 mm square, and is on the n ⁻ -GaN layer 202 in the opening of the insulating film 300 and from the periphery of the opening of the insulating film 300 to the insulating film 300 side. A field plate withstand voltage structure in which the first electrode 30 is arranged in a range up to 50 μm is adopted.

  Next, referring to FIG. 17C, a 50 nm thick Ni layer, a 400 nm thick Pt layer, and a barrier film 330 are formed on the entire surface of the first electrode 30 and the insulating film 300 by the EB vapor deposition method. An Au layer having a thickness of 100 nm was formed. Such a barrier film 330 can prevent deterioration of Schottky characteristics due to diffusion of metal atoms in the bonding metal film in a bonding process which is a subsequent process.

  Next, an Ni layer having a thickness of 50 nm, a Pt layer having a thickness of 400 nm, and an Au layer having a thickness of 100 nm were formed as pad electrodes 43 to be ohmic electrodes on the device support substrate 40 by an EB vapor deposition method. Further, an AuSn film (Au is 70 mass% and Sn is 30 mass%) having a thickness of 5 μm was formed as the bonding metal film 44 on the pad electrode 43 by resistance heating vapor deposition.

  Here, the device support substrate 40 has a low resistance (specific resistance is less than 1 mΩ · cm) and a p-type Si substrate in Examples J1 to J10 and J12 (when the diameter is 75 mm, the thickness is 400 μm, and the diameter is 100 mm). In Example J11, Example J13, and Example J14, a Mo substrate (a thickness of 400 μm when the diameter is 100 mm, and a thickness of 600 μm when the diameter is 150 μm) was used.

  Next, the bonding metal film 44 and the barrier film 330 were bonded using a wafer bonder. The bonding conditions were 10 minutes at 300 ° C. in a vacuum atmosphere of less than 1 Pa. After joining, the state of the joining surface was observed with an ultrasonic microscope. Thus, the laminated substrate 3 was obtained.

Next, with reference to FIG. 17D1, using a surface grinder, the support substrate 11 of the multilayer substrate 3 was ground from the exposed main surface to a thickness of 50 μm. Next, the support substrate 11 and the bonding film 12 of the group III nitride composite substrate 1 were removed from the multilayer substrate 3 by etching using hydrofluoric acid. Thereafter, the group III nitride film 13 exposed by removing the support substrate 11 and the bonding film 12 from the multilayer substrate 3 is etched by 200 nm from the exposed main surface using Cl ₂ as an etching gas by the ICP-RIE method. Etched to depth.

  Next, referring to FIG. 17 (E1), a Ti layer having a plane shape of 1.4 mm square and a thickness of 20 nm, an Al layer having a thickness of 100 nm is formed on the Group III nitride film 13 by EB vapor deposition. An ohmic electrode as the second electrode 50 was formed by sequentially forming a Ti layer having a thickness of 20 nm and an Au layer having a thickness of 300 nm. Further, a Ni layer having a planar shape of 1.4 mm square, a thickness of 10 nm, a Pt layer having a thickness of 10 nm, and an Au layer having a thickness of 100 nm are sequentially formed on the device support substrate 40 by EB vapor deposition. Thereby, the ohmic electrode which is the device support substrate electrode 45 was formed. Here, the 2nd electrode 50 and the device support substrate electrode 45 were formed in the position corresponding to the position in which the 1st electrode 30 is formed. In Example J11, Example J13, and Example J14, since the Mo substrate used as the device support substrate 40 also serves as an ohmic electrode, the device support substrate electrode 45 was not formed.

Next, the group III nitride semiconductor device 4 on which the first electrode 30 and the second electrode 50 were formed was annealed at 250 ° C. for 3 minutes in an N ₂ atmosphere using RTA. Thus, a group III nitride semiconductor device 4 was obtained.

  The obtained group III nitride semiconductor device 4 was chipped as follows. The group III nitride semiconductor device 4 including a Si substrate as the device support substrate 40 is attached to a UV (ultraviolet) curable dicing tape with the second electrode 50 side down, and a pattern of the electrode is obtained using a dicer. Accordingly, the device was cut to a depth of up to 370 μm from the main surface on the device support substrate 40 side, and then the dicing part was broken using a breaking device to form a chip. The group III nitride semiconductor device 4 including a Mo substrate as the device support substrate 40 is attached to a UV (ultraviolet) curable dicing tape with the device support substrate 40 side down, and a pattern of the electrode is obtained using a dicer. First, the group III nitride layer was cut, and then the Mo substrate as the device support substrate was cut to form a chip. Here, using a blade having a thickness of 200 μm for dicing the group III nitride layer and using a blade having a thickness of 100 μm for dicing the device support substrate, chipping (chip) of the group III nitride layer was prevented. .

  The total number of group III nitride semiconductor devices obtained by the above-mentioned chip formation from the entire surface excluding the outer peripheral portion 5 mm on the main surface of each group III nitride semiconductor device is 150 from the substrate having a diameter of 75 mm, and the substrate having a diameter of 100 mm. The number was 300, and the number was 700 from the substrate having a diameter of 150 mm.

The chip-type group III nitride semiconductor device obtained as described above was subjected to current-voltage characteristic measurement using a prober. The forward characteristic index is the forward voltage Vf when the current density is 500 A / cm ^2, and the reverse characteristic index is the reverse withstand voltage Vr when the current density is 1 × 10 ⁻³ A / cm ^2. It was. Here, when the group III nitride semiconductor device is SBD, a group III nitride semiconductor device having a forward voltage Vf of 1.5 V or less and a reverse withstand voltage Vr of 500 V or more was determined as a good product. The ratio of the number of group III nitride semiconductor devices in which the forward voltage Vf is 1.5 V or less to the total number of group III nitride semiconductor devices is called Vf yield, and the reverse withstand voltage Vr is 500 V or more. The ratio of the number of group III nitride semiconductor devices is called Vr yield. Table 10 summarizes the characteristic values of the obtained group III nitride semiconductor device formed into a chip.

  Referring to Table 10, as shown in Example J1, Example J2, and Example J3, a group III nitride composite substrate having a group III nitride film thickness of 100 μm, 50 μm, 10 μm, and 10 μm or more, respectively, is used. The group III nitride semiconductor device had a high Vf yield and Vr yield of 60% or more. As shown in Example J4 and Example J5, a Group III nitride semiconductor device fabricated using a Group III nitride composite substrate having a Group III nitride film thickness of less than 7 μm, 0.5 μm, and 10 μm, respectively, Vr yield decreased. This was presumably because the group III nitride film was thin and the crystal quality was lowered.

Further, III-group absolute values for the ratio s _o / m _o off angle of the primary surface of the group III nitride film is 0.2 and 0.4 and 0.6 respectively, as shown in Examples J1 and Example J6 A group III nitride semiconductor device manufactured using a nitride composite substrate had a high Vf yield and Vr yield of 55% or more. Group III absolute values for the ratio s _o / m _o off angle of the primary surface of the group III nitride film is fabricated using the 0.8 and 0.6 greater than the group III nitride composite substrate as shown in Example J7 Nitride semiconductor devices both had a Vf yield of 20% and a Vr yield of 40%. Further, with reference to Example J8 and Example J9, for each grouped group III nitride semiconductor device, the average absolute value of the components in the [10-10] direction of the off-angle of the main surface of the group III nitride film When the relationship between m _om and Vf yield was examined, when the average value m _om was smaller than 0.30 ° and 0.4 °, the Vf yield was lowered, and the average value _om was 0.20 ° and 0.2 _% . When the angle was smaller than 3 °, the Vf yield further decreased.

Impurities in the group III nitride layer were measured by SIMS (secondary ion mass spectrometry), and the average value of the absolute values of the components in the [10-10] direction of the off angle of the main surface of the group III nitride film Since the concentration of carbon impurities increased when m _om was smaller than 0.4 °, the on-resistance increased by decreasing the carrier concentration of the n ⁻ -GaN layer (drift layer) of the group III nitride layer. As a result, it was considered that the Vf yield decreased, and the reverse leakage current increased, resulting in a decrease in the Vr yield. Further, when the average value m _om of the absolute value of the component in the [10-10] direction of the off-angle of the main surface of the group III nitride film was smaller than 0.3 °, the concentration of the carbon impurity was further increased. As a result, the carrier concentration of the n ⁻ -GaN layer (drift layer) of the group III nitride layer is further reduced, so that the on-resistance is further increased, the Vf yield is further decreased, and the reverse leakage current is reduced. It was considered that the Vr yield further decreased and the Vr yield further decreased. This was thought to be due to a decrease in crystal quality due to an increase in the concentration of carbon impurities in the group III nitride layer.

  As shown in Examples J1 to J9, in the group III nitride semiconductor device manufactured using the group III nitride composite substrate including the mullite supporting substrate having a diameter of 75 mm, the group III nitride film of the group III nitride composite substrate is used. The group III nitride layer epitaxially grown on the surface had no cracks, and the bonding surface between the group III nitride layer and the device supporting substrate had no defects such as voids and was a good bond.

As shown in Example J10 and Example J11, the group III nitride layer epitaxially grown on the group III nitride film of the group III nitride composite substrate including a mullite substrate having a diameter of 100 mm as a support substrate has cracks on the outer periphery thereof. It occurred and was bad. As shown in Examples J12 and J13, the Group III nitride layer epitaxially grown on the Group III nitride film of the Group III nitride composite substrate including a mullite-YSZ substrate having a diameter of 100 mm as the supporting substrate has cracks. It was very good. As shown in Example J14, a group III nitride layer epitaxially grown on a group III nitride film of a group III nitride composite substrate including a mullite-YSZ substrate having a diameter of 150 mm as a support substrate is free from cracks and is good. there were. Cracks occurred when the support substrate was a mullite substrate with a diameter of 100 mm, and cracks did not occur when the support substrate was a mullite-YSZ substrate with a diameter of 100 mm and 150 mm. The thermal expansion coefficient of the mullite-YSZ substrate was GaN This is probably because the thermal expansion coefficient of the layer was almost the same. Here, when measured with a differential expansion type thermal expansion measuring apparatus, the thermal expansion coefficient of the mullite substrate is 4.8 × 10 ⁻⁶ K ⁻¹ , and the thermal expansion coefficient of the mullite-YSZ substrate is 5.6 × 10 6. ⁻⁶ K ⁻¹ , and the thermal expansion coefficient in the direction parallel to the (0001) plane of the GaN layer was 5.6 × 10 ⁻⁶ K ⁻¹ .

As shown in Examples J10 and J12, when a Si substrate having a diameter of 100 mm was used as the device support substrate, an unbonded region was observed at a part of the bonding surface between the group III nitride layer and the device support substrate. It was done. For those using a Mo substrate with a diameter of 100 mm as the device support substrate as shown in Example J11 and Example J13, and those using a Mo substrate with a diameter of 150 mm as the device support substrate as shown in Example J14 Bonding of the bonding surface between the layer and the device support substrate was good, and no unbonded region was observed. As described above, the reason why the bonding failure occurred in the device using the Si substrate having a diameter of 100 mm as the device supporting substrate was that the Si substrate side was warped in a convex shape on the Si substrate side, as shown in FIG. This was probably because the difference between the thermal expansion coefficient of the layer III and the laminated group III nitride composite substrate was large. Here, the thermal expansion coefficient of the laminated group III nitride composite substrate is 4.8 × 10 ⁻⁶ K ⁻¹ which is the thermal expansion coefficient of the mullite substrate when the support substrate is a mullite substrate, and the thermal expansion coefficient of the GaN layer. 5.6 × 10 ⁻⁶ K ⁻¹ , and when the support substrate is a mullite-YSZ substrate, the thermal expansion coefficient of the mullite-YSZ substrate and the GaN layer is 5.6 × 10 ⁻⁶ K ^{−. 1} was considered. Moreover, the thermal expansion coefficient of the Si substrate was 3.0 × 10 ⁻⁶ K ⁻¹ , and the thermal expansion coefficient of the Mo substrate was 5.1 × 10 ⁻⁶ K ⁻¹ .

  As shown in Examples J10 to J12, since a mullite substrate having a diameter of 100 mm was used as the support substrate, cracks occurred in the outer peripheral portion of the group III nitride layer (Example J10 and Example J11). In the case of using a Si substrate with a diameter of 100 mm, a non-bonded region was generated on the bonding surface between the device support substrate and the group III nitride layer, so that both the Vf yield and the Vr yield were lowered.

  On the other hand, as shown in Example J13, a mullite-YSZ substrate having a diameter of 100 mm is used as a support substrate and a Mo substrate having a diameter of 100 mm is used as a device support substrate, and as shown in Example J14, a support substrate is 150 mm in diameter. In the case of using a mullite-YSZ substrate and a Mo substrate having a diameter of 150 mm as the device support substrate, the group III nitride layer was good and the bonding between the device support substrate and the group III nitride layer was also good. , Vf yield and Vr yield were both high.

(Example K)
In this example, referring to FIG. 18, a PND (pn junction diode) which is a group III nitride semiconductor device including a device support substrate 40 was manufactured.

1. Production of Group III Nitride Composite Substrate Except for the following points, a mullite substrate as a support substrate, a SiO ₂ film as a bonding film, and a GaN crystal as a group III nitride film donor substrate are used as in Example J Thus, a Group III nitride composite substrate having a diameter of 75 mm was produced.

In Examples K1 to K3, by changing the cutting position by the wire saw when cutting the group III nitride film donor substrate, the average value of the thickness of the group III nitride film is set to 100 μm (Example K1), The thickness was set to 10 μm (Example K2) and 6 μm (Example K3). In Example K4, it was manufactured by the same method as that of the BP substrate of Example C, and the average thickness of the group III nitride film was 0.5 μm. In Examples K1 to K4, the main surface of the group III nitride film 13 was turned off by 0.40 ° in the [10-10] direction from the (0001) plane. Further, the absolute value m _oa of the component in the [1-210] direction of the main surface of the main surface of the group III nitride film 13 from the (0001) plane was set to 0.1 ° or less. Table 11 summarizes the physical properties of the group III nitride composite substrates of Examples K1 to K4.

2. Production of Group III Nitride Semiconductor Device Referring to FIG. 18A, a carrier stop layer is formed on group III nitride film 13 of group III nitride composite substrate 1 as group III nitride layer 20 by MOVPE. n carrier concentration thick with a carrier concentration of 2 × 10 ¹⁸ cm ^-3 is n ⁺ -GaN layer 203, n-type carrier drift layer of 1μm thickness at 1 × 10 ¹⁶ cm ^-3 is 5μm is ^- -GaN layer 204, the Mg concentration is p-type layer thickness at 5 × 10 ¹⁷ cm ^-3 is 0.5 [mu] m ^p - -GaN layer 205, and an ohmic contact layer Mg concentration of 1 × 10 ²⁰ cm ^- The p ⁺ -GaN layer 206 having a thickness of 0.05 μm in FIG. ³ was epitaxially grown in order to obtain a laminated group III nitride composite substrate 2. Here, the growth temperature of the group III nitride layer 20 is 1050 ° C., TMG (trimethylgallium) and NH ₃ are used as the GaN raw material, SiH ₄ is used as the Si dopant raw material, and CP ₂ is used as the Mg dopant raw material. Mg (cyclopentadienyl magnesium) was used. The average value and the standard deviation of the absolute value of the main surface of the group III nitride layer 20 with respect to the (0001) plane are the absolute value of the off angle with respect to the (0001) plane of the main surface of the group III nitride film. The mean value and standard deviation were the same.

Next, referring to FIG. 18B, a resist mask (not shown) is formed on the group III nitride layer 20 of the laminated group III nitride composite substrate 2 by photolithography, and RIE (reactive ion etching) is performed. ) To perform mesa etching. The size of the top and bottom surfaces of the mesa portion was 1.4 mm square, and the height of the mesa portion (etching depth) was 0.8 μm. Next, a Ni layer having a planar shape of 1.1 mm square, a thickness of 50 nm, and an Au layer having a thickness of 100 nm are formed on the side of the p ⁺ -GaN layer 206 of the group III nitride layer 20 by photolithography, EB deposition, and lift-off. By forming sequentially, the 1st electrode 30 which is an ohmic electrode was formed, and alloying heat processing was carried out.

Next, referring to FIG. 18C, a SiN _x film was formed as insulating film 300 on first electrode 30 and group III nitride layer 20 by plasma CVD. Next, using photolithography and buffered hydrofluoric acid, the insulating film 300 on the first electrode 30 was etched away to a size of 1.0 mm square to form an opening, and the first electrode 30 was exposed. Next, a 50 nm thick Ni layer, a 400 nm thick Pt layer, and a 100 nm thick Au layer were sequentially formed as a barrier film 330 on the insulating film 300 and the exposed first electrode 30 by EB vapor deposition. The barrier film 330 can prevent deterioration of device characteristics due to diffusion of metal atoms in the bonding metal film 44 in bonding with the bonding metal film 44 formed on the device support substrate 40 described later. Next, in the same manner as in Example J, a Si substrate was prepared as the device support substrate 40, and the pad electrode 43 and the bonding metal film 44 were formed on the device support substrate 40.

  Next, in the same manner as in Example J, the bonding metal film 44 and the barrier film 330 were bonded. After joining, the state of the joining surface was observed with an ultrasonic microscope. Thus, the laminated substrate 3 was obtained.

  Next, referring to FIG. 18D1, in the same manner as in Example J, after grinding a part of the support substrate 11, the support substrate 11 and the bonding film 12 of the group III nitride composite substrate 1 are hooked. It removed by etching using hydrofluoric acid. Thereafter, the group III nitride film 13 exposed by removing the support substrate 11 and the bonding film 12 from the multilayer substrate 3 was etched to a depth of 200 nm from the exposed main surface in the same manner as in Example J.

  Next, referring to FIG. 18E1, as in Example J, a second electrode 50 having a planar shape of 1.4 mm square is formed on the group III nitride film 13, and the device support substrate 40 is formed. A device supporting substrate electrode having a planar shape of 1.4 mm square was formed thereon. Thus, a group III nitride semiconductor device 4 was obtained.

  Next, the obtained group III nitride semiconductor device 4 was chipped by dicing and breaking in the same manner as in Example J.

  With respect to the chip-formed group III nitride semiconductor device obtained as described above, the Vf yield and the Vr yield were determined in the same manner as in Example J except for the following points. That is, when the group III nitride semiconductor device is a PND, a group III nitride semiconductor device having a forward voltage Vf of 4 V or less and a reverse withstand voltage Vr of 700 V or more is regarded as a good product. The ratio of the number of group III nitride semiconductor devices in which the forward voltage Vf is 4 V or less to the total number of group III nitride semiconductor devices is called Vf yield, and the reverse withstand voltage Vr is 700 V or more. The ratio of the number of group nitride semiconductor devices is called Vr yield. Table 11 summarizes the characteristic values of the obtained group III nitride semiconductor device formed into a chip.

  Referring to Table 11, as shown in Example K1 and Example K2, the Group III nitride fabricated using the Group III nitride composite substrate having a Group III nitride film thickness of 100 μm, 10 μm, and 10 μm or more, respectively The semiconductor device had a high Vf yield and Vr yield of 60% or more. As shown in Example K3 and Example K4, a Group III nitride semiconductor device fabricated using a Group III nitride composite substrate having a Group III nitride film thickness of less than 6 μm, 0.5 μm, and 10 μm, respectively, Vr yield decreased. This was presumably because the group III nitride film was thin and the crystal quality was lowered.

(Example L)
In this example, referring to FIG. 19, an SBD which is a group III nitride semiconductor device including the support substrate 10 was manufactured.

1. Production of Group III Nitride Composite Substrate Using a Mo substrate or a W substrate as a support substrate, and using a highly conductive Ga ₂ O ₃ film with a specific resistance of 10 mΩ · cm as a bonding film, except for the following points: In the same manner as in Example J, a group III nitride composite substrate was produced. Here, the Ga ₂ O ₃ film was formed by sputtering.

In Examples L1 to L4, the thickness of the group III nitride film was changed by changing the cutting position by the wire saw when cutting the group III nitride film donor substrate using a Mo substrate having a diameter of 75 mm as the support substrate. Were set to 100 μm (Example L1), 50 μm (Example L2), 10 μm (Example L3), and 7 μm (Example L4), respectively. In Example L5, it was manufactured by the same method as that of the BP substrate of Example C, and the average thickness of the group III nitride film was 0.5 μm. In Example L6, a W substrate having a diameter of 75 mm is used as a support substrate, in Example L7, a W substrate having a diameter of 100 mm is used, in Example L8, a Mo substrate having a diameter of 100 mm is used as a support substrate, and in Example L9, a support is used. A W substrate having a diameter of 150 mm was used as the substrate, and in Example L10, a Mo substrate having a diameter of 150 mm was used as the support substrate. In Examples L1 to L10, the main surface of the group III nitride film 13 was turned off by 0.40 ° in the [10-10] direction from the (0001) plane. Further, the absolute value m _oa of the component in the [1-210] direction of the main surface of the main surface of the group III nitride film 13 from the (0001) plane was set to 0.1 ° or less. Table 12 summarizes the physical properties of the Group III nitride composite substrates of Example L1 to Example L10.

2. Production of Group III Nitride Semiconductor Device Referring to FIG. 19A, a group III nitride layer 20 is formed on group III nitride film 13 of group III nitride composite substrate 1 as in Example J. The n ⁺ -GaN layer 201 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of 1 μm as a carrier stop layer, and the carrier concentration of 1 × 10 ¹⁶ cm ⁻³ and a thickness of 5 μm as a carrier drift layer. The n ⁻ -GaN layers 202 were sequentially epitaxially grown to obtain a laminated group III nitride composite substrate 2. The average value and the standard deviation of the absolute value of the main surface of the group III nitride layer 20 with respect to the (0001) plane are the absolute value of the off angle with respect to the (0001) plane of the main surface of the group III nitride film. The mean value and standard deviation were the same.

Next, referring to FIG. 19B, on the n ⁻ -GaN layer 202 that is the uppermost layer of the group III nitride layer 20 of the laminated group III nitride composite substrate 2, in the same manner as in Example J, An insulating film 300 having an opening was formed as a field plate. Here, the planar shape of each opening of the insulating film 300 was 1 mm square.

Next, a patterned Schottky electrode was formed as the first electrode 30 in the same manner as in Example J. The planar shape of each Schottky electrode as the first electrode 30 is 1.1 mm square, and is on the n ⁻ -GaN layer 202 in the opening of the insulating film 300 and from the periphery of the opening of the insulating film 300 to the insulating film 300 side. A field plate withstand voltage structure in which the first electrode 30 is arranged in a range up to 50 nm is adopted. Thus, a group III nitride semiconductor device 4 was obtained.

  In FIG. 19B, the second electrode 50, which is an ohmic electrode, is formed on the support substrate 11, but both the Mo substrate and the W substrate used as the support substrate 11 in this embodiment are ohmic electrodes. Therefore, the second electrode 50 was not provided on the support substrate 11.

  The obtained group III nitride semiconductor device 4 was diced using a dicer so as to have a planar shape of 1.5 mm square according to the electrode pattern. The total number of group III nitride semiconductor devices obtained by the above-mentioned chip formation from the entire surface excluding the outer peripheral portion 5 mm on the main surface of each group III nitride semiconductor device is 150 from the substrate having a diameter of 75 mm, and the substrate having a diameter of 100 mm. The number was 300, and the number was 700 from the substrate having a diameter of 150 mm.

  With respect to the chip-formed group III nitride semiconductor device obtained as described above, the Vf yield and the Vr yield were determined in the same manner as in Example J. Table 12 summarizes the characteristic values of the obtained group III nitride semiconductor device formed into a chip.

  Referring to Table 12, as shown in Example L1, Example L2, and Example L3, a group III nitride composite substrate having a group III nitride film thickness of 100 μm, 50 μm, 10 μm, and 10 μm or more is used. The group III nitride semiconductor device had a high Vf yield and Vr yield of 55% or more. As shown in Example L4 and Example L5, a Group III nitride semiconductor device fabricated using a Group III nitride composite substrate having a Group III nitride film thickness of less than 7 μm, 0.5 μm, and 10 μm, respectively, Vr yield decreased. This was presumably because the group III nitride film was thin and the crystal quality was lowered. As shown in Example L5, the Group III nitride semiconductor device fabricated using the Group III nitride composite substrate having a Group III nitride film thickness of 0.5 μm also had a decreased Vf yield. This was thought to be due to the presence of a high resistance layer by ion implantation in the group III nitride film. In the group III nitride semiconductor device of Example J5 in Example J, the Vf yield was high because the high resistance layer of the group III nitride film was removed by etching before the formation of the second electrode. It was.

  As shown in Example L6, the group III nitride layer epitaxially grown on the group III nitride film of the group III nitride composite substrate including the W substrate having a diameter of 75 mm as the support substrate has no cracks and its appearance is It was good. As shown in Example L7, the group III nitride layer epitaxially grown on the group III nitride film of the group III nitride composite substrate including the W substrate having a diameter of 100 mm as the support substrate has cracks generated on the outer periphery thereof. The appearance was poor. As shown in Example L9, a group III nitride layer epitaxially grown on a group III nitride film of a group III nitride composite substrate including a W substrate having a diameter of 150 mm as a supporting substrate has cracks in the outer peripheral portion and the central portion thereof. The appearance was extremely poor.

  On the other hand, as shown in Example L8, the group III nitride layer epitaxially grown on the group III nitride film of the group III nitride composite substrate including the Mo substrate having a diameter of 100 mm as the support substrate has cracks. The appearance was good. Further, as shown in Example L10, the group III nitride layer epitaxially grown on the group III nitride film of the group III nitride composite substrate including the Mo substrate having a diameter of 150 mm as the support substrate has no cracks, and the Appearance was good.

In this way, when a group III nitride composite substrate including a W substrate as a support substrate was used, the appearance of the group III nitride layer became poor as the diameter increased from 75 mm to 100 mm, 150 mm, When the group III nitride composite substrate including the Mo substrate was used as the support substrate, the appearance of the group III nitride layer was good even when the diameter increased from 75 mm to 100 mm and 150 mm. compared to the expansion coefficient ^{(4.5 × 10 -6 K -1)} , the thermal expansion coefficient of the Mo substrate (5.1 × 10 ^-6 K ^-1) thermal expansion coefficient of GaN layer (5.6 × 10 ^{- This} was considered to be close to ⁶ K ⁻¹ ).

  In addition, as shown in Example L6, a Group III nitride semiconductor device manufactured using a Group III nitride composite substrate including a W substrate having a diameter of 75 mm as a support substrate has a Vf yield and a Vr yield of 60. It was high with more than%. As shown in Example L7, a Group III nitride semiconductor device manufactured using a Group III nitride composite substrate including a W substrate having a diameter of 100 mm as a support substrate has a Vf yield and a Vr yield of 50% or more. Less than 60% was almost satisfactory. As shown in Example L9, the group III nitride semiconductor device manufactured using a group III nitride composite substrate including a W substrate having a diameter of 150 mm as a supporting substrate had low Vf yield and Vr yield.

  On the other hand, as shown in Example L8, a group III nitride semiconductor device manufactured using a group III nitride composite substrate including a Mo substrate with a diameter of 100 mm as a support substrate has a Vf yield and a Vr yield. Both were high at 65% or more. As shown in Example L10, a Group III nitride semiconductor device manufactured using a Group III nitride composite substrate including a Mo substrate having a diameter of 150 mm as a supporting substrate has a Vf yield and a Vr yield of 55% or more. It was good at less than 60%.

(Example M)
In this example, referring to FIG. 20, a PND which is a group III nitride semiconductor device including the support substrate 10 was manufactured.

1. Production of Group III Nitride Composite Substrate A group III nitride composite substrate was produced in the same manner as in Example L except that the Mo substrate having a diameter of 75 mm was used as the support substrate and the following points were used.

  In Examples M1 to M3, by changing the cutting position by the wire saw when cutting the group III nitride film donor substrate, the average value of the thickness of the group III nitride film is 100 μm (Example M1), The thickness was set to 10 μm (Example M2) and 6 μm (Example M3). In Example M4, it was manufactured by the same method as that of the BP substrate of Example C, and the average thickness of the group III nitride film was 0.5 μm.

2. Fabrication of Group III Nitride Semiconductor Device Referring to FIG. 20A, a group III nitride layer 20 is formed on group III nitride film 13 of group III nitride composite substrate 1 in the same manner as in Example K. The n ⁺ -GaN layer 203 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a thickness of 1 μm, which is a carrier stop layer, and a thickness of 1 × 10 ¹⁶ cm ⁻³ and a carrier concentration of an n-type carrier drift layer. An n ⁻ -GaN layer 204 of 5 μm, a p ⁻ -GaN layer 205 having a Mg concentration of 5 × 10 ¹⁷ cm ⁻³ and a thickness of 0.5 μm as a p-type layer, and an Mg concentration of 1 × as an ohmic contact layer. A laminated group III nitride composite substrate 2 was obtained by epitaxially growing a p ⁺ -GaN layer 206 having a thickness of 10 ²⁰ cm ⁻³ and a thickness of 0.05 μm in this order. The average value and the standard deviation of the absolute value of the main surface of the group III nitride layer 20 with respect to the (0001) plane are the absolute value of the off angle with respect to the (0001) plane of the main surface of the group III nitride film. The mean value and standard deviation were the same.

Next, referring to FIG. 20B, mesa etching was performed on group III nitride layer 20 of laminated group III nitride composite substrate 2 in the same manner as in Example K. The size of the upper and bottom surfaces of the mesa portion was 1.4 mm square, and the height (etching depth) of the mesa portion was 0.8 μm. Next, in the same manner as in Example K, a Ni layer having a planar shape of 1.1 mm square and a thickness of 50 nm and an Au layer having a thickness of 100 nm are sequentially formed on the p ⁺ -GaN layer 206 side of the group III nitride layer 20. By forming, the 1st electrode 30 which is an ohmic electrode was formed, and alloying heat processing was performed. Thus, a group III nitride semiconductor device 4 was obtained.

  In FIG. 20B, the second electrode 50, which is an ohmic electrode, is formed on the support substrate 11, but also functions as a Mo substrate ohmic electrode used as the support substrate 11 in this embodiment. The second electrode 50 was not provided on the support substrate 11.

  The obtained group III nitride semiconductor device 4 was made into a chip by dicing using the dicer so that the planar shape was 1.5 mm square, in accordance with the pattern of the electrode, as in Example L. . The total number of group III nitride semiconductor devices obtained by the above-described chip formation from the entire surface excluding the outer peripheral portion of 5 mm on the main surface of each group III nitride semiconductor device was 150 from a substrate having a diameter of 75 mm.

  With respect to the chip-formed group III nitride semiconductor device obtained as described above, the Vf yield and the Vr yield were determined in the same manner as in Example K. Table 13 summarizes the characteristic values of the obtained grouped III-nitride semiconductor device.

  Referring to Table 13, as shown in Example M1 and Example M2, a group III nitride fabricated using a group III nitride composite substrate in which the thickness of the group III nitride film is 100 μm, 10 μm, and 10 μm or more, respectively The semiconductor device had a high Vf yield and Vr yield of 65% or more. As shown in Example M3 and Example M4, a Group III nitride semiconductor device fabricated using a Group III nitride composite substrate having a Group III nitride film thickness of less than 6 μm, 0.5 μm, and 10 μm, respectively, Vr yield greatly decreased. This was presumably because the group III nitride film was thin and the crystal quality was lowered. As shown in Example M4, a Group III nitride semiconductor device manufactured using a Group III nitride composite substrate having a Group III nitride film thickness of 0.5 μm has a Vf yield higher than that of Examples M1 to M3. It dropped a little. This was thought to be due to the presence of a high resistance layer by ion implantation in the group III nitride film. In the group III nitride semiconductor device of Example K4 in Example K, the reason why the Vf yield was high is considered to be that the high resistance layer of the group III nitride film was removed by etching before forming the second electrode. It was.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Group III nitride composite substrate 1L, 1LS Bonded substrate 2 Stacked group III nitride composite substrate 3 Stacked substrate 4 Group III nitride semiconductor device 5D, 5Dr Group III nitride film donor substrate with support 11 Support substrate 12, 14 Bonded Film 13 Group III nitride film 13D, 13Dr Group III nitride film donor substrate 13i Ion implantation region 15 Group III nitride film donor substrate support 20 Group III nitride layer 21 n-GaN layer 22 n-In _0.05 Ga _0.95 N Layer 23 Active layer 24 p-Al _0.09 Ga _0.91 N layer 25 p-GaN layer 26 GaN layer 27 Al _0.2 Ga _0.8 N layer 30 First electrode 33, 43 Pad electrode 40 Device support substrate 44 Bonding metal film 45 Device support substrate electrode 50 second electrode 60 source electrode 70 drain electrode 80 gate electrode 201, 203 n ⁺ -GaN layer 202 ^- -GaN layer 205 ^p - -GaN layer 206 p ⁺ -GaN layer 300 insulating film 330 barrier film

Claims (18)

A III-nitride composite substrate having a diameter of 75 mm or more obtained by laminating a supporting substrate and a III-nitride film having a thickness of 10 μm or more and 250 μm or less,
Wherein a ratio s _t / m _t of the standard deviation s _t of the thickness to the average value m _t of the thickness of the III nitride film is 0.001 to 0.2, the major surface of the III nitride film the ratio s _o / m _o of the standard deviation s _o of the absolute value of the off-angle with respect to the average value m _o of the absolute value of the off angle relative to the plane of the predetermined plane orientation of 0.005 to 0.6, III group Nitride composite substrate.   The III-nitride composite substrate according to claim 1, wherein warpage of the group III nitride composite substrate on the main surface on the group III nitride film side is 50 µm or less, and an overall thickness distribution of the group III nitride composite substrate is 30 µm or less. Group nitride composite substrate. The ratio α _III-N / α _S of the thermal expansion coefficient alpha _III-N of the III nitride film to the thermal expansion coefficient alpha _S of the support substrate is 0.75 to 1.25, the thickness of the support substrate group III nitride composite he is according to claim 1 or claim 2 ratio t _III-N / t _S of thickness t _III-N of the III nitride film is 0.02 or more and 1 or less with respect to t _S substrate. 4. The group III nitride composite substrate according to claim 1, wherein the number of impurity metal atoms in the main surface of the group III nitride film is 3 × 10 ¹² atoms / cm ² or less.   The group III nitride composite substrate according to any one of claims 1 to 4, wherein a root mean square roughness of the main surface of the group III nitride film is 3 nm or less.   The group III nitride composite substrate according to any one of claims 1 to 5, wherein a root mean square roughness of a main surface of the support substrate is 12 nm or less.   The group III nitride composite substrate according to any one of claims 1 to 6, wherein the diameter is 100 mm or more.   The group III nitride composite substrate according to any one of claims 1 to 7, wherein the diameter is 125 mm or more and 300 mm or less. The main surface of the group III nitride film has an average value of root mean square roughness m _III-N of 0.1 nm to 2 nm and a standard deviation s _{III-N of} root mean square roughness of 0. 4 nm or less,
The mean value m _S of the root mean square roughness of the main surface of the support substrate is 0.3 nm or more and 10 nm or less, and the standard deviation s _S of the root mean square roughness is 3 nm or less. Item 11. The group III nitride composite substrate according to any one of items 8 to 9. The average value m _om of the components in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the principal surface of the group III nitride film is 0.3 ° or more and 1.0 ° or less. 2. The group III nitride composite substrate according to claim 1, wherein an average value m _oa of absolute values of components in the <1-210> direction of the off angle is 0 ° or more and 0.1 ° or less.   The group III nitride composite substrate according to claim 1 or 10, and at least one group III nitride layer disposed on the group III nitride film of the group III nitride composite substrate. A laminated group III nitride composite substrate.   The group III nitride film in the group III nitride composite substrate according to claim 1 or 10, and at least one group III nitride layer disposed on the group III nitride film, Group III nitride semiconductor device comprising. Including at least one III-nitride layer;
The ratio s _Lo / m _Lo of the standard deviation s _Lo of the absolute value of the off angle to the average value m _Lo of the absolute value of the off angle with respect to the plane of the predetermined plane orientation of the principal surface of the group III nitride layer is 0.005 or more Group III nitride semiconductor device that is 0.6 or less. The average value m _Lom of the components in the <10-10> direction of the off angle with respect to the plane of the predetermined plane orientation of the principal surface of the group III nitride layer is 0.3 ° or more and 1.0 ° or less. The group III nitride semiconductor device according to claim 13, wherein an average value m _Loa of components in the <1-210> direction of the off angle is not less than 0 ° and not more than 0.1 °. A method for producing a group III nitride composite substrate according to claim 1 or 10,
Bonding the support substrate and the group III nitride film donor substrate to form a bonded substrate having a diameter of 75 mm or more;
The group III nitride composite substrate is cut by cutting the group III nitride film donor substrate at a surface located at a predetermined distance from the bonding main surface of the group III nitride film donor substrate of the bonding substrate. Forming a group III nitride composite substrate. A method for producing a group III nitride composite substrate according to claim 1 or 10,
Bonding the support substrate and the group III nitride film donor substrate to form a bonded substrate having a diameter of 75 mm or more;
Forming the group III nitride composite substrate by performing at least one of grinding, polishing and etching from the main surface opposite to the bonding main surface of the group III nitride film donor substrate of the bonding substrate; The manufacturing method of the group III nitride composite substrate containing these. Preparing a group III nitride composite substrate according to claim 1 or claim 10;
And a step of growing at least one group III nitride layer on the group III nitride film of the group III nitride composite substrate.   The group III nitride semiconductor device according to claim 17, further comprising: bonding a device support substrate on the group III nitride layer; and removing the support substrate from the group III nitride composite substrate. Manufacturing method.

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