JP2020132482A - Manufacturing method of semiconductor substrate, and ground substrate used therefor - Google Patents
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Abstract
Description
本発明は、半導体基板の製造方法及びそれに用いる下地基板に関する。 The present invention relates to a method for manufacturing a semiconductor substrate and a base substrate used therein.
高効率の発光デバイスやパワーデバイスを得るためには、転位密度の低い高品質なＧａＮ基板が必要である。例えば、特許文献１及び２には、転位密度の低いＧａＮ基板を製造することを目的として、下地基板上に複数のＧａＮの三角ファセット構造を形成した後、相互に隣接する三角ファセット構造間の凹部を埋め込むように第１厚膜成長層を形成し、複数の三角ファセット構造のそれぞれの上に逆三角形の第２厚膜成長層を形成するとともに、相互に隣接する第２厚膜成長層を合体させて第１厚膜成長層を埋設することが開示されている。また、非特許文献１及び２にも、ＧａＮを低転位化する技術が開示されている。 In order to obtain high-efficiency light-emitting devices and power devices, a high-quality GaN substrate with low dislocation density is required. For example, in Patent Documents 1 and 2, for the purpose of producing a GaN substrate having a low dislocation density, after forming a plurality of GaN triangular facet structures on a base substrate, recesses between the triangular facet structures adjacent to each other are formed. The first thick film growth layer is formed so as to embed, and the second thick film growth layer of inverted triangle is formed on each of the plurality of triangular facet structures, and the second thick film growth layers adjacent to each other are united. It is disclosed that the first thick film growth layer is embedded. In addition, Non-Patent Documents 1 and 2 also disclose techniques for lowering dislocations of GaN.
本発明の課題は、転位が分散した半導体基板の製造方法を提供することである。 An object of the present invention is to provide a method for manufacturing a semiconductor substrate in which dislocations are dispersed.
本発明は、各々、所定方向に沿った断面形状が相対的に小さい三角形を構成するように半導体が結晶成長した複数の小三角ファセット構造を、それらが前記所定方向に並んで配設されるように形成するステップと、各々、前記複数の小三角ファセット構造のうちの２以上を取り込むとともに、前記所定方向に沿った断面形状が相対的に大きい三角形を構成するように前記半導体が結晶成長した複数の大三角ファセット構造を、それらが前記所定方向に並んで配設されるように形成するステップとを含む半導体基板の製造方法である。 In the present invention, a plurality of small triangular facet structures in which semiconductors are crystal-grown so as to form triangles having a relatively small cross-sectional shape along a predetermined direction are arranged side by side in the predetermined direction. A plurality of steps in which the semiconductor is crystal-grown so as to form a triangle having a relatively large cross-sectional shape along the predetermined direction while incorporating two or more of the plurality of small triangular facet structures. It is a method of manufacturing a semiconductor substrate including a step of forming the large triangular facet structure of the above so that they are arranged side by side in the predetermined direction.
本発明は、半導体基板を製造するために用いられる下地基板であって、基板本体と、前記基板本体上に一定周期で間隔をおいて設けられた複数の長周期マスクと、前記基板本体上における相互に隣接する前記長周期マスク間に一定周期で間隔をおいて設けられた前記長周期マスクとは構成の異なる複数の短周期マスクと、
を備える。
The present invention is a base substrate used for manufacturing a semiconductor substrate, which comprises a substrate main body, a plurality of long-period masks provided on the substrate main body at regular intervals, and on the substrate main body. A plurality of short-period masks having a configuration different from that of the long-period masks provided at regular intervals between the long-period masks adjacent to each other,
To be equipped.
本発明によれば、複数の小三角ファセット構造を形成し、各々、その複数の小三角ファセット構造のうちの２以上を取り込んだ複数の大三角ファセット構造を形成することにより、転位が分散した半導体基板を製造することができる。 According to the present invention, a semiconductor in which dislocations are dispersed by forming a plurality of small triangular facet structures and forming a plurality of large triangular facet structures each incorporating two or more of the plurality of small triangular facet structures. Substrates can be manufactured.
以下、実施形態について図面に基づいて詳細に説明する。 Hereinafter, embodiments will be described in detail with reference to the drawings.
実施形態に係る半導体基板の製造方法は、下地基板準備工程と半導体結晶成長工程とを備える。なお、以下では、ＧａＮを半導体とするＧａＮ基板の製造例を示すが、特にこれに限定されるものではなく、半導体がＡｌＧａＮ、ＩｎＧａＮ、ＩｎＡｌＧａＮ、ＩｎＡｌＮ、ＩｎＮ等であってもよい。 The method for manufacturing a semiconductor substrate according to the embodiment includes a base substrate preparation step and a semiconductor crystal growth step. In the following, an example of manufacturing a GaN substrate using GaN as a semiconductor will be shown, but the present invention is not particularly limited, and the semiconductor may be AlGaN, InGaN, InAlGaN, InAlN, InN, or the like.
（下地基板準備工程）
下地基板準備工程では、ＧａＮ基板を製造するために用いられる図１Ａ〜１Ｃに示すような下地基板１０を準備する。下地基板１０は、基板本体１１と、各々、その上に設けられた長周期マスク１２及び短周期マスク１３とを備える。
(Base board preparation process)
In the base substrate preparation step, the base substrate 10 as shown in FIGS. 1A to 1C used for manufacturing the GaN substrate is prepared. The base substrate 10 includes a substrate main body 11 and a long-period mask 12 and a short-period mask 13 provided on the substrate main body 11, respectively.
基板本体１１は、マスク間に露出する本体表面が、後にそこから結晶成長させる同一の半導体のＧａＮで構成されていることが好ましい。したがって、基板本体１１は、ＧａＮ基板、又は、例えば、サファイア基板、ＺｎＯ基板、ＳｉＣ基板等の基材表面にＧａＮ膜が設けられたものであることが好ましい。基板表面を構成するＧａＮの主面は、特に限定されるものではないが、ｃ面であることが好ましい。なお、基板本体１１は、例えば、サファイア基板、ＺｎＯ基板、ＳｉＣ基板等であってもよい。 It is preferable that the surface of the main body exposed between the masks of the substrate main body 11 is made of GaN of the same semiconductor that crystal grows from there later. Therefore, the substrate body 11 is preferably a GaN substrate or one in which a GaN film is provided on the surface of a substrate such as a sapphire substrate, a ZnO substrate, or a SiC substrate. The main surface of GaN constituting the substrate surface is not particularly limited, but is preferably the c-plane. The substrate body 11 may be, for example, a sapphire substrate, a ZnO substrate, a SiC substrate, or the like.
長周期マスク１２は、例えば、二酸化珪素（ＳｉＯ２）、窒化珪素（ＳｉＮｘ）等で形成されている。長周期マスク１２は、基板本体１１上に、複数が一定周期Ｐ１で間隔Ｗ１をおいて一方向に平行にストライプ状に延びるように設けられている。長周期マスク１２は、幅方向が基板本体１１のａ軸方向又はｍ軸方向に一致するように設けられていることが好ましい。 The long-period mask 12 is made of, for example, silicon dioxide (SiO 2 ), silicon nitride (SiNx), or the like. Long periodic mask 12 on the substrate main body 11, a plurality are provided so as to extend in parallel to stripes in one direction at a distance W 1 at a predetermined period P 1. The long-period mask 12 is preferably provided so that the width direction coincides with the a-axis direction or the m-axis direction of the substrate main body 11.
長周期マスク１２の幅ｗ１は、好ましくは１０μｍ以上１００μｍ以下、より好ましくは１０μｍ以上５０μｍ以下、更に好ましくは１０μｍ以上２０μｍ以下である。長周期マスク１２の幅ｗ１は、長さ方向に一定であることが好ましい。 The width w 1 of the long-period mask 12 is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less, and further preferably 10 μm or more and 20 μm or less. The width w 1 of the long-period mask 12 is preferably constant in the length direction.
相互に隣接する長周期マスク１２間の間隔Ｗ１は、好ましくは１００μｍ以上３０００μｍ以下、より好ましくは１００μｍ以上１０００μｍ以下、更に好ましくは１００μｍ以上９００μｍ以下、より更に好ましくは１００μｍ以上５００μｍ以下である。相互に隣接する長周期マスク１２間の間隔Ｗ１は、長さ方向に一定であることが好ましい。相互に隣接する長周期マスク１２間の間隔Ｗ１は、長周期マスク１２の幅ｗ１よりも大きいことが好ましい。相互に隣接する長周期マスク１２間の間隔Ｗ１の長周期マスク１２の幅ｗ１に対する比（Ｗ１／ｗ１）は、好ましくは５以上５０以下、より好ましくは５以上２５以下、更に好ましくは１０以上２５以下である。 The interval W 1 between the long cycle masks 12 adjacent to each other is preferably 100 μm or more and 3000 μm or less, more preferably 100 μm or more and 1000 μm or less, still more preferably 100 μm or more and 900 μm or less, and further preferably 100 μm or more and 500 μm or less. Distance W 1 between the long periodic mask 12 adjacent to each other is preferably constant in the longitudinal direction. The interval W 1 between the long cycle masks 12 adjacent to each other is preferably larger than the width w 1 of the long cycle mask 12. The ratio (W 1 / w 1 ) of the interval W 1 between the long cycle masks 12 adjacent to each other to the width w 1 of the long cycle mask 12 is preferably 5 or more and 50 or less, more preferably 5 or more and 25 or less, still more preferable. Is 10 or more and 25 or less.
長周期マスク１２の幅ｗ１及び相互に隣接する長周期マスク１２間の間隔Ｗ１の和、すなわち、長周期マスク１２の周期Ｐ１は、好ましくは１００μｍ以上１０００μｍ以下、より好ましくは１００μｍ以上５００μｍ以下である。長周期マスク１２の厚さは、好ましくは１０ｎｍ以上５００ｎｍ以下、より好ましくは１０ｎｍ以上２００ｎｍ以下である。 The sum of the width w 1 of the long cycle mask 12 and the interval W 1 between the long cycle masks 12 adjacent to each other, that is, the period P 1 of the long cycle mask 12 is preferably 100 μm or more and 1000 μm or less, more preferably 100 μm or more and 500 μm. It is as follows. The thickness of the long-period mask 12 is preferably 10 nm or more and 500 nm or less, and more preferably 10 nm or more and 200 nm or less.
短周期マスク１３は、例えば、二酸化珪素（ＳｉＯ２）、窒化珪素（ＳｉＮｘ）等で形成されている。短周期マスク１３は、基板本体１１上に長周期マスク１２及び短周期マスク１３を同時形成する観点から、長周期マスク１２と同一材料で形成されていることが好ましい。短周期マスク１３は、基板本体１１上における相互に隣接する長周期マスク１２間に、長周期マスク１２と平行に、複数が一定周期Ｐ２で間隔Ｗ２をおいて一方向に平行にストライプ状に延びるように設けられている。 The short cycle mask 13 is made of, for example, silicon dioxide (SiO 2 ), silicon nitride (SiNx), or the like. The short cycle mask 13 is preferably formed of the same material as the long cycle mask 12 from the viewpoint of simultaneously forming the long cycle mask 12 and the short cycle mask 13 on the substrate main body 11. Short periodic mask 13, between the long periodic mask 12 adjacent to each other on the substrate main body 11, parallel to the long periodic mask 12, parallel to stripes in one direction at a distance W 2 more at a constant period P 2 It is provided so as to extend to.
短周期マスク１３は、その幅ｗ２が長周期マスク１２とは構成が異なる。短周期マスク１３の幅ｗ２は、長周期マスク１２の幅ｗ１よりも小さいことが好ましい。短周期マスク１３の幅ｗ２は、好ましくは１μｍ以上１５μｍ以下、より好ましくは２μｍ以上１０μｍ以下、更に好ましくは３μｍ以上５μｍ以下である。短周期マスク１３の幅ｗ２の長周期マスク１２の幅ｗ１に対する比（ｗ２／ｗ１）は、好ましくは１／１０以上１／２以下である。短周期マスク１３の幅ｗ２は、長さ方向に一定であることが好ましい。 The width w 2 of the short cycle mask 13 is different from that of the long cycle mask 12. The width w 2 of the short cycle mask 13 is preferably smaller than the width w 1 of the long cycle mask 12. The width w 2 of the short cycle mask 13 is preferably 1 μm or more and 15 μm or less, more preferably 2 μm or more and 10 μm or less, and further preferably 3 μm or more and 5 μm or less. The ratio to the width w 1 of the long periodic mask 12 having a width w 2 of the short-period mask 13 (w 2 / w 1) is preferably 1/10 to 1/2. The width w 2 of the short cycle mask 13 is preferably constant in the length direction.
相互に隣接する短周期マスク１３間の間隔Ｗ２は、好ましくは１０μｍ以上８０μｍ以下、より好ましくは１５μｍ以上６０μｍ以下、更に好ましくは２０μｍ以上４０μｍ以下である。相互に隣接する短周期マスク１３間の間隔Ｗ２は、相互に隣接する長周期マスク１２間の間隔Ｗ１よりも短いが、前者の後者に対する比（Ｗ２／Ｗ１）は、好ましくは１／１０以上１／２以下、より好ましくは１／５以上１／２以下である。相互に隣接する短周期マスク１３間の間隔Ｗ２は、長さ方向に一定であることが好ましい。相互に隣接する短周期マスク１３間の間隔Ｗ２は、幅方向の両端の短周期マスク１３のそれぞれと、それに隣接した長周期マスク１２との間隔と同一であることが好ましい。つまり、相互に隣接する長周期マスク１２間の間隔Ｗ１が複数の短周期マスク１３によって等分割されていることが好ましい。 The interval W 2 between the short cycle masks 13 adjacent to each other is preferably 10 μm or more and 80 μm or less, more preferably 15 μm or more and 60 μm or less, and further preferably 20 μm or more and 40 μm or less. The interval W 2 between the short cycle masks 13 adjacent to each other is shorter than the interval W 1 between the long cycle masks 12 adjacent to each other, but the ratio (W 2 / W 1 ) of the former to the latter is preferably 1. It is / 10 or more and 1/2 or less, more preferably 1/5 or more and 1/2 or less. The interval W 2 between the short cycle masks 13 adjacent to each other is preferably constant in the length direction. The spacing W 2 between the short cycle masks 13 adjacent to each other is preferably the same as the spacing between each of the short cycle masks 13 at both ends in the width direction and the long cycle mask 12 adjacent thereto. That is, it is preferable that the interval W 1 between the long cycle masks 12 adjacent to each other is equally divided by the plurality of short cycle masks 13.
相互に隣接する短周期マスク１３間の間隔Ｗ２は、短周期マスク１３の幅ｗ２よりも大きいことが好ましい。相互に隣接する短周期マスク１３間の間隔Ｗ２の短周期マスク１３の幅ｗ２に対する比（Ｗ２／ｗ２）は、好ましくは２以上２０以下、より好ましくは５以上１５以下、更に好ましくは８以上１２以下である。相互に隣接する短周期マスク１３間の間隔Ｗ２の短周期マスク１３の幅ｗ２に対する比（Ｗ２／ｗ２）は、相互に隣接する長周期マスク１２間の間隔Ｗ１の長周期マスク１２の幅ｗ１に対する比（Ｗ１／ｗ１）よりも小さいことが好ましい。 The distance W 2 between the short cycle masks 13 adjacent to each other is preferably larger than the width w 2 of the short cycle mask 13. The ratio (W 2 / w 2 ) of the interval W 2 between the short cycle masks 13 adjacent to each other to the width w 2 of the short cycle mask 13 is preferably 2 or more and 20 or less, more preferably 5 or more and 15 or less, still more preferable. Is 8 or more and 12 or less. The ratio (W 2 / w 2 ) of the interval W 2 between the short cycle masks 13 adjacent to each other to the width w 2 of the short cycle mask 13 is the long cycle mask of the interval W 1 between the long cycle masks 12 adjacent to each other. It is preferably smaller than the ratio of 12 to the width w 1 (W 1 / w 1 ).
短周期マスク１３の幅ｗ２及び相互に隣接する短周期マスク１３間の間隔Ｗ２の和、すなわち、短周期マスク１３の周期Ｐ２は、好ましくは１０μｍ以上８０μｍ以下、より好ましくは１５μｍ以上６０μｍ以下、更に好ましくは２０μｍ以上４０μｍ以下である。短周期マスク１３の厚さは、好ましくは１０ｎｍ以上５００ｎｍ以下、より好ましくは１０ｎｍ以上２００ｎｍ以下である。短周期マスク１３の厚さは、基板本体１１上に長周期マスク１２及び短周期マスク１３を同時形成する観点から、長周期マスク１２の厚さと同一であることが好ましい。なお、長周期のマスク１２を選択成長させれば、短周期マスク１３の厚さを、長周期のマスク１２の厚さよりも薄くすることも可能である。 The sum of the width w 2 of the short cycle mask 13 and the interval W 2 between the short cycle masks 13 adjacent to each other, that is, the period P 2 of the short cycle mask 13 is preferably 10 μm or more and 80 μm or less, more preferably 15 μm or more and 60 μm. Hereinafter, it is more preferably 20 μm or more and 40 μm or less. The thickness of the short cycle mask 13 is preferably 10 nm or more and 500 nm or less, and more preferably 10 nm or more and 200 nm or less. The thickness of the short cycle mask 13 is preferably the same as the thickness of the long cycle mask 12 from the viewpoint of simultaneously forming the long cycle mask 12 and the short cycle mask 13 on the substrate main body 11. If the long-cycle mask 12 is selectively grown, the thickness of the short-cycle mask 13 can be made thinner than the thickness of the long-cycle mask 12.
（半導体結晶成長工程）
半導体結晶成長工程では、気相成長装置を用い、反応室において、気相成長法のＨＶＰＥ法（ハイドライド気相成長法：Hydride Vapor Phase Epitaxy）により、下地基板１０の長周期マスク１２及び短周期マスク１３を設けた側の表面に原料ガスを接触させることにより半導体のＧａＮを結晶成長させる。原料ガスには、Ｇａ源ガスとしてＧａとＨＣｌガスとから得られるＧａＣｌガスが挙げられ、Ｎ源ガスとしてＮＨ３ガスが挙げられる。また、キャリアガスとして例えばＨ２ガスやＮ２ガスが挙げられる。
(Semiconductor crystal growth process)
In the semiconductor crystal growth step, a gas phase growth apparatus is used, and in the reaction chamber, the long cycle mask 12 and the short cycle mask of the base substrate 10 are subjected to the HVPE method (Hydride Vapor Phase Epitaxy) of the gas phase growth method. The semiconductor GaN is crystal-grown by bringing the raw material gas into contact with the surface on the side provided with 13. Examples of the raw material gas include GaCl gas obtained from Ga and HCl gas as the Ga source gas, and NH 3 gas as the N source gas. Further, examples of the carrier gas include H 2 gas and N 2 gas.
実施形態に係る半導体基板の製造方法の半導体結晶成長工程は、小三角ファセット構造形成ステップ、大三角ファセット構造形成ステップ、及び厚膜成長ステップを含む。 The semiconductor crystal growth step of the method for manufacturing a semiconductor substrate according to the embodiment includes a small triangular facet structure forming step, a large triangular facet structure forming step, and a thick film growing step.
＜小三角ファセット構造形成ステップ＞
小三角ファセット構造形成ステップでは、図２Ａ及びＢに示すように、下地基板１０のマスク間に露出した基板本体１１の本体表面を起点としてＧａＮを結晶成長させる。このとき、ＧａＮは、長周期マスク１２及び短周期マスク１３により結晶成長が規制され、マスク間に露出した基板本体１１の本体表面からエピタキシャル成長する。したがって、マスク間に露出した基板本体１１の本体表面がＧａＮのｃ面であれば、ＧａＮがｃ面成長する。そして、ＧａＮは、各マスク間において、結晶成長するに従って所定方向である長周期マスク１２及び短周期マスク１３の幅方向の寸法が両側から漸次狭くなった後に最終的に線状に収束する。
<Small triangular facet structure formation step>
In the small triangular facet structure forming step, as shown in FIGS. 2A and 2B, GaN is crystal-grown from the main body surface of the substrate main body 11 exposed between the masks of the underlying substrate 10. At this time, the crystal growth of GaN is regulated by the long-period mask 12 and the short-period mask 13, and the GaN grows epitaxially from the main body surface of the substrate main body 11 exposed between the masks. Therefore, if the main body surface of the substrate main body 11 exposed between the masks is the c-plane of GaN, the GaN grows on the c-plane. Then, the GaN finally converges linearly between the masks after the dimensions in the width direction of the long-period mask 12 and the short-period mask 13 which are predetermined directions gradually narrow from both sides as the crystal grows.
以上のようにして、下地基板１０上に、各々、長周期マスク１２及び短周期マスク１３の幅方向に沿った断面形状が相対的に小さい三角形を構成するようにＧａＮが結晶成長した突条の複数の小三角ファセット構造２１を、それらが長周期マスク１２及び短周期マスク１３の幅方向に並んで配設されるように形成する。ここで、本出願における「三角形」は、３本の線分の辺で構成された三角形の他、３本の辺のうちの少なくとも１本が弓形に外向きに膨出又は内向きに没入した略三角形も含む。 As described above, the ridges in which GaN is crystal-grown on the base substrate 10 so as to form triangles having a relatively small cross-sectional shape along the width direction of the long-period mask 12 and the short-period mask 13, respectively. A plurality of small triangular facet structures 21 are formed so that they are arranged side by side in the width direction of the long cycle mask 12 and the short cycle mask 13. Here, the "triangle" in the present application is a triangle composed of the sides of three line segments, and at least one of the three sides bulges outward or immerses inward in a bow shape. Also includes abbreviated triangles.
小三角ファセット構造形成ステップでのＧａＮの結晶成長条件は、小三角ファセット構造２１の形成に好適なように適宜選択すればよい。 The GaN crystal growth conditions in the small triangular facet structure forming step may be appropriately selected so as to be suitable for forming the small triangular facet structure 21.
＜大三角ファセット構造形成ステップ＞
大三角ファセット構造形成ステップでは、図３Ａ及びＢに示すように、小三角ファセット構造２１上にＧａＮを結晶成長させる。このとき、ＧａＮは、小三角ファセット構造２１の表面からエピタキシャル成長する。そして、ＧａＮは、各長周期マスク１２間において、それらの間に形成された小三角ファセット構造２１を全て取り込み、結晶成長するに従って長周期マスク１２及び短周期マスク１３の幅方向の寸法が両側から漸次狭くなった後に最終的に線状に収束する。
<Large triangular facet structure formation step>
In the large triangular facet structure forming step, as shown in FIGS. 3A and 3B, GaN is crystal-grown on the small triangular facet structure 21. At this time, GaN grows epitaxially from the surface of the small triangular facet structure 21. Then, GaN incorporates all the small triangular facet structures 21 formed between the long-period masks 12, and as the crystal grows, the dimensions of the long-period mask 12 and the short-period mask 13 in the width direction increase from both sides. After gradually narrowing, it finally converges linearly.
以上のようにして、下地基板１０上に、各々、長周期マスク１２間の小三角ファセット構造２１を全て取り込むとともに、長周期マスク１２及び短周期マスク１３の幅方向に沿った断面形状が相対的に大きい三角形を構成するようにＧａＮが結晶成長した突条の複数の大三角ファセット構造２２を、それらが長周期マスク１２及び短周期マスク１３の幅方向に並んで配設されるように形成する。なお、この大三角ファセット構造形成ステップは、小三角ファセット構造形成ステップと同時進行であってもよい。 As described above, all the small triangular facet structures 21 between the long-period masks 12 are incorporated on the base substrate 10, and the cross-sectional shapes of the long-period mask 12 and the short-period mask 13 along the width direction are relative. A plurality of large triangular facet structures 22 of ridges in which GaN is crystal-grown so as to form a large triangle are formed so as to be arranged side by side in the width direction of the long-period mask 12 and the short-period mask 13. .. The large triangular facet structure forming step may proceed simultaneously with the small triangular facet structure forming step.
大三角ファセット構造形成ステップでのＧａＮの結晶成長条件は、小三角ファセット構造形成ステップと同一であってもよく、大三角ファセット構造２２の形成に好適なように適宜選択すればよい。 The GaN crystal growth conditions in the large triangular facet structure forming step may be the same as those in the small triangular facet structure forming step, and may be appropriately selected so as to be suitable for forming the large triangular facet structure 22.
＜厚膜成長ステップ＞
厚膜成長ステップでは、大三角ファセット構造２２上にＧａＮを結晶成長させる。このとき、図４Ａに示すように、ＧａＮは、複数の大三角ファセット構造２２のそれぞれの斜面の斜めファセット面からエピタキシャルラテラル成長（Epitaxial Lateral Overgrowth：以下「ＥＬＯ成長」という。）して相互に隣接する大三角ファセット構造２２間の凹部を埋め込むように第１厚膜成長層２３を形成する（第１厚膜成長ステップ）。それと同時に、ＧａＮは、複数の大三角ファセット構造２２のそれぞれの上に、その頂上に連続して、大三角ファセット構造２２の底面、したがって、下地基板１０の表面のマスク間に露出した基板本体１１の本体表面と同一の結晶成長面で結晶成長し、結晶成長に伴って長周期マスク１２及び短周期マスク１３の幅方向の寸法が両側に漸次拡大し、長周期マスク１２及び短周期マスク１３の幅方向に沿った断面形状が逆三角形を構成するように第２厚膜成長層２４を形成する（第２厚膜成長ステップ）。そして、これらの第１及び第２厚膜成長層２３，２４に加え、小三角ファセット構造２１及び大三角ファセット構造２２を含み、全体として単一のＧａＮ層２０（半導体層）が構成される。
<Thick film growth step>
In the thick film growth step, GaN is crystal-grown on the large triangular facet structure 22. At this time, as shown in FIG. 4A, the GaNs are epitaxially laterally grown (Epitaxial Lateral Overgrowth: hereinafter referred to as “ELO growth”) from the diagonal facet planes of the respective slopes of the plurality of large triangular facet structures 22 and are adjacent to each other. The first thick film growth layer 23 is formed so as to embed the recesses between the large triangular facet structures 22 (first thick film growth step). At the same time, the GaN is exposed on the top of each of the plurality of large triangular facet structures 22 and continuously on the top of the bottom surface of the large triangular facet structure 22, and thus the substrate body 11 exposed between the masks on the surface of the base substrate 10. The crystal grows on the same crystal growth surface as the surface of the main body, and the width direction dimensions of the long cycle mask 12 and the short cycle mask 13 gradually expand to both sides as the crystal grows, and the long cycle mask 12 and the short cycle mask 13 The second thick film growth layer 24 is formed so that the cross-sectional shape along the width direction forms an inverted triangle (second thick film growth step). Then, in addition to these first and second thick film growth layers 23 and 24, a small triangular facet structure 21 and a large triangular facet structure 22 are included, and a single GaN layer 20 (semiconductor layer) is formed as a whole.
また、下地基板１０の構成及びＧａＮの結晶成長条件を適宜選択すれば、図４Ｂに示すように、ＧａＮは、複数の大三角ファセット構造２２のそれぞれの斜面の斜めファセット面からＥＬＯ成長して相互に隣接する大三角ファセット構造２２間の凹部を埋め込むように第１厚膜成長層２３を形成する（第１厚膜成長ステップ）。しかる後、ＧａＮは、第１厚膜成長層２３の形成とともに、複数の大三角ファセット構造２２のそれぞれの上に、大三角ファセット構造２２の頂上から間隔をおいて、大三角ファセット構造２２の底面と同一の結晶成長面で結晶成長し、結晶成長に伴って長周期マスク１２及び短周期マスク１３の幅方向の寸法が両側に漸次拡大し、長周期マスク１２及び短周期マスク１３の幅方向に沿った断面形状が逆三角形を構成するように第２厚膜成長層２４を形成する（第２厚膜成長ステップ）。そして、これらの第１及び第２厚膜成長層２３，２４に加え、小三角ファセット構造２１及び大三角ファセット構造２２を含んで、全体として単一のＧａＮ層２０（半導体層）が構成される。 Further, if the configuration of the base substrate 10 and the crystal growth conditions of GaN are appropriately selected, as shown in FIG. 4B, GaN grows ELO from the diagonal facet planes of the respective slopes of the plurality of large triangular facet structures 22 and mutually. The first thick film growth layer 23 is formed so as to embed the recesses between the large triangular facet structures 22 adjacent to the first thick film growth layer (first thick film growth step). After that, along with the formation of the first thick film growth layer 23, GaN is placed on each of the plurality of large triangular facet structures 22 at intervals from the top of the large triangular facet structure 22 and the bottom surface of the large triangular facet structure 22. The crystal grows on the same crystal growth plane as the above, and the width direction of the long cycle mask 12 and the short cycle mask 13 gradually expands to both sides as the crystal grows, and the width direction of the long cycle mask 12 and the short cycle mask 13 The second thick film growth layer 24 is formed so that the cross-sectional shape along the line forms an inverted triangle (second thick film growth step). Then, in addition to these first and second thick film growth layers 23 and 24, a small triangular facet structure 21 and a large triangular facet structure 22 are included to form a single GaN layer 20 (semiconductor layer) as a whole. ..
ここで、本出願における「逆三角形」は、３本の線分の辺で構成された逆三角形の他、３本の辺のうちの少なくとも１本が弓形に外向きに膨出又は内向きに没入した略逆三角形も含む。 Here, the "inverted triangle" in the present application is an inverted triangle composed of the sides of three line segments, and at least one of the three sides bulges outward or inward in a bow shape. Also includes immersive approximately inverted triangles.
第１及び第２厚膜成長層２３，２４におけるＧａＮの結晶成長が進むと、図５Ａ（図４Ａに対応）及び５Ｂ（図４Ｂに対応）に示すように、第１厚膜成長層２３による相互に隣接する大三角ファセット構造２２間の凹部の埋め込みが完了し、それに続いて、複数の大三角ファセット構造２２の上の複数の第２厚膜成長層２４が合体することにより第１厚膜成長層２３を埋設し、最終的に、小三角ファセット構造２１及び大三角ファセット構造２２並びに第１及び第２厚膜成長層２３，２４を含むＧａＮ層２０の表面の平坦化が図られる。 As the crystal growth of GaN in the first and second thick film growth layers 23 and 24 progresses, it depends on the first thick film growth layer 23 as shown in FIGS. 5A (corresponding to FIG. 4A) and 5B (corresponding to FIG. 4B). The embedding of the recesses between the adjacent large triangular facet structures 22 is completed, and subsequently, the plurality of second thick film growth layers 24 on the plurality of large triangular facet structures 22 are united to form the first thick film. The growth layer 23 is embedded, and finally, the surface of the GaN layer 20 including the small triangular facet structure 21, the large triangular facet structure 22, and the first and second thick film growth layers 23 and 24 is flattened.
厚膜成長ステップでのＧａＮの結晶成長条件は、小三角ファセット構造形成ステップ又は大三角ファセット構造形成ステップと同一であってもよく、第１及び第２厚膜成長層２３，２４の形成に好適なように適宜選択すればよい。 The GaN crystal growth conditions in the thick film growth step may be the same as those in the small triangular facet structure formation step or the large triangular facet structure formation step, and are suitable for the formation of the first and second thick film growth layers 23 and 24. It may be selected as appropriate.
以上のようにして下地基板１０上に作製したＧａＮ層２０に水平方向に亀裂を入れて下地基板１０から分離することにより半導体基板のＧａＮ基板を得ることができる。この実施形態に係る半導体基板の製造方法によれば、上記の通り、下地基板１０上に、複数の小三角ファセット構造２１を形成し、各々、その複数の小三角ファセット構造２１のうちの２以上を取り込んだ複数の大三角ファセット構造２２を形成することにより、転位が分散したＧａＮ基板を製造することができる。これは、小三角ファセット構造２１からのＥＬＯ成長及び大三角ファセット構造２２からのＥＬＯ成長の２回のＥＬＯ成長により、転位の集中と分散とが２回起こったためであると考えられる。 The GaN substrate of the semiconductor substrate can be obtained by horizontally cracking the GaN layer 20 produced on the substrate 10 as described above and separating the GaN layer 20 from the substrate 10. According to the method for manufacturing a semiconductor substrate according to this embodiment, as described above, a plurality of small triangular facet structures 21 are formed on the base substrate 10, and two or more of the plurality of small triangular facet structures 21 are formed. By forming a plurality of large triangular facet structures 22 incorporating the above, a GaN substrate in which dislocations are dispersed can be manufactured. It is considered that this is because the concentration and dispersion of dislocations occurred twice due to the two ELO growths of the ELO growth from the small triangular facet structure 21 and the ELO growth from the large triangular facet structure 22.
得られたＧａＮ基板は、半導体発光素子（ＬＥＤ）、半導体レーザ（ＬＤ）、太陽電池、その他の電子デバイス等に用いることができる。このＧａＮ基板は、転位が分散しているので、リーク電流を低減することができるという観点から、パワーデバイスに用いることが特に好適である。 The obtained GaN substrate can be used for semiconductor light emitting elements (LEDs), semiconductor lasers (LDs), solar cells, other electronic devices, and the like. Since the dislocations are dispersed, this GaN substrate is particularly suitable for use in power devices from the viewpoint of being able to reduce leakage current.
なお、上記実施形態では、各々、一方向にストライプ状に延びる長周期マスク１２及び短周期マスク１３が設けられた下地基板１０を用いたが、特にこれに限定されるものではなく、例えば、図６に示すように、基板本体１１上に、平面視で相対的に大きい複数の六角形のハニカム形状を形成するように長周期マスク１２が設けられるとともに、長周期マスク１２の各六角形内に、平面視で相対的に小さい複数の六角形のハニカム形状を形成するように短周期マスク１３が設けられ、したがって、三方向にストライプ状に延びる長周期マスク１２及び短周期マスク１３が設けられた下地基板１０を用いてもよい。 In the above embodiment, the base substrate 10 provided with the long-period mask 12 and the short-period mask 13 extending in a stripe shape in one direction is used, but the present invention is not particularly limited thereto, and for example, FIG. As shown in 6, a long-period mask 12 is provided on the substrate main body 11 so as to form a plurality of hexagonal honeycomb shapes that are relatively large in a plan view, and inside each hexagon of the long-period mask 12. The short-period mask 13 is provided so as to form a plurality of hexagonal honeycomb shapes that are relatively small in a plan view, and therefore, the long-period mask 12 and the short-period mask 13 extending in a stripe shape in three directions are provided. The base substrate 10 may be used.
また、上記実施形態では、短周期マスク１３が長周期マスク１２と幅が異なる構成としたが、特にこれに限定されるものではなく、短周期マスク１３が長周期マスク１２と幅が同一で且つ厚さが異なる構成であってもよい。 Further, in the above embodiment, the short cycle mask 13 has a different width from the long cycle mask 12, but the width is not particularly limited to this, and the short cycle mask 13 has the same width as the long cycle mask 12 and has the same width. The configurations may have different thicknesses.
また、上記実施形態では、長周期マスク１２及び短周期マスク１３の２種のマスクを設けた下地基板１０を用いて小三角ファセット構造２１及び大三角ファセット構造２２の二段階で三角ファセット構造を形成する構成としたが、特にこれに限定されるものではなく、短周期マスク間に一定周期で間隔をおいて第３のマスクを設けた下地基板を用いて三段階で三角ファセット構造を形成する構成であってもよく、更に４種以上のマスクを設けた下地基板を用いて多段階で三角ファセット構造を形成する構成であってもよい。 Further, in the above embodiment, a triangular facet structure is formed in two stages of a small triangular facet structure 21 and a large triangular facet structure 22 by using a base substrate 10 provided with two types of masks, a long cycle mask 12 and a short cycle mask 13. However, the configuration is not particularly limited to this, and a triangular facet structure is formed in three stages using a base substrate provided with a third mask at regular intervals between short-cycle masks. It may be a configuration in which a triangular facet structure is formed in multiple stages by using a base substrate provided with four or more types of masks.
（ＧａＮ層の形成）
以下の実施例１〜３及び比較例のＧａＮ層の形成実験を行った。なお、表１には、それぞれで用いた下地基板の構成を示す。
(Formation of GaN layer)
The following GaN layer formation experiments of Examples 1 to 3 and Comparative Examples were carried out. Table 1 shows the configurations of the base substrates used in each of them.
＜実施例１＞
主面がｃ面のサファイア基板上にＭＯＶＰＥ法で厚さ３μｍ程度のＧａＮ膜をエピタキシャル成長させた基板本体１１上に、各々、ａ軸方向に延びるようにストライプ状に延びるＳｉＯ２の長周期マスク１２及び短周期マスク１３を設けた下地基板１０を作製した。図７Ａに示すように、長周期マスク１２の幅ｗ１を１０μｍ及び長周期マスク１２間の間隔Ｗ１を２００μｍとした。短周期マスク１３の幅ｗ２を３μｍ及び短周期マスク１３間の間隔Ｗ２を２６μｍとし、長周期マスク１２間の間隔Ｗ１を短周期マスク１３で７等分に分割した。
<Example 1>
A long-period mask 12 of SiO 2 extending in a stripe shape so as to extend in the a-axis direction on a substrate main body 11 in which a GaN film having a thickness of about 3 μm is epitaxially grown on a sapphire substrate having a c-plane main surface by the MOVPE method. And the base substrate 10 provided with the short-period mask 13 was produced. As shown in FIG. 7A, the width w 1 of the long cycle mask 12 was set to 10 μm, and the interval W 1 between the long cycle mask 12 was set to 200 μm. The width w 2 of the short cycle mask 13 was 3 μm, the interval W 2 between the short cycle masks 13 was 26 μm, and the interval W 1 between the long cycle masks 12 was divided into 7 equal parts by the short cycle mask 13.
そして、この下地基板上にＨＶＰＥ法でＧａＮを結晶成長させた。具体的には、図８に示すように、まず、Ｎ２ガスを流しながら、下地基板の温度を５００℃まで昇温した。下地基板の温度が５００℃になったとき、Ｎ２ガスを停止するとともに、Ｈ２ガス及びＮＨ３ガスを流し始めた。Ｈ２ガス及びＮＨ３ガスを流しながら、下地基板の温度を更に１０４０℃まで昇温した。しかる後、Ｈ２ガス及びＮＨ３ガスに加えてＨＣｌガスを流し始め、ＨＣｌガスを１８０分間流して下地基板上にＧａＮを結晶成長させた（第１ステップ）。このとき、ＨＣｌガスの流量を０．４０ｓｌｍ及びＮＨ３ガスの流量を２４．０ｓｌｍとした（Ｖ／ＩＩＩ比＝６０）。 Then, GaN was crystal-grown on this base substrate by the HVPE method. Specifically, as shown in FIG. 8, first, while flowing N 2 gas, the temperature of the starting substrate was heated to 500 ° C.. When the temperature of the base substrate reached 500 ° C., the N 2 gas was stopped and the H 2 gas and the NH 3 gas were started to flow. While flowing H 2 gas and NH 3 gas was further heated to 1040 ° C. The temperature of the starting substrate. After that, HCl gas was started to flow in addition to H 2 gas and NH 3 gas, and HCl gas was flowed for 180 minutes to grow GaN crystal on the base substrate (first step). At this time, the flow rate of the HCl gas was 0.40 slm and the flow rate of the NH 3 gas was 24.0 slm (V / III ratio = 60).
次いで、ＨＣｌガスの供給時間が１８０分になったときにＨＣｌガスを停止し、その後、Ｈ２ガス及びＮＨ３ガスを継続して流しながら、下地基板の温度を１１００℃まで昇温した。下地基板の温度が１１００℃になったとき再びＨＣｌガスを流し始め、ＨＣｌガスを３３０分間流してＧａＮを結晶成長させた（第２ステップ）。このとき、ＨＣｌガスの流量を０．８０ｓｌｍ及びＮＨ３ガスの流量を８．０ｓｌｍとした（Ｖ／ＩＩＩ比＝１０）。 Then, when the supply time of the HCl gas reached 180 minutes, the HCl gas was stopped, and then the temperature of the underlying substrate was raised to 1100 ° C. while continuously flowing the H 2 gas and the NH 3 gas. When the temperature of the underlying substrate reached 1100 ° C., HCl gas was started to flow again, and HCl gas was flowed for 330 minutes to grow GaN crystal (second step). At this time, the flow rate of the HCl gas was 0.80 slm and the flow rate of the NH 3 gas was 8.0 slm (V / III ratio = 10).
続いて、ＨＣｌガスの供給時間が３３０分になったときＨＣｌガスを停止し、Ｈ２ガス及びＮＨ３ガスを継続して流しながら、下地基板の温度を１０００℃まで下げた。下地基板の温度が１０００℃になったとき再びＨＣｌガスを流し始め、ＨＣｌガスを３０分間流してＧａＮを結晶成長させた（第３ステップ）。このとき、ＨＣｌガスの流量は０．２６ｓｌｍ及びＮＨ３ガスの流量は８．０ｓｌｍとした（Ｖ／ＩＩＩ比＝３０）。 Subsequently, when the supply time of the HCl gas reached 330 minutes, the HCl gas was stopped, and the temperature of the base substrate was lowered to 1000 ° C. while continuously flowing the H 2 gas and the NH 3 gas. When the temperature of the underlying substrate reached 1000 ° C., HCl gas was started to flow again, and HCl gas was flowed for 30 minutes to grow GaN crystals (third step). At this time, the flow rate of the HCl gas was 0.26 slm and the flow rate of the NH 3 gas was 8.0 slm (V / III ratio = 30).
ＨＣｌガスの供給時間が３０分になったときＨＣｌガスを停止し、Ｈ２ガス及びＮＨ３ガスを継続して流しながら、下地基板の温度を３００℃まで下げた。下地基板の温度が３００℃になったとき、Ｈ２ガス及びＮＨ３ガスを停止するとともに、Ｎ２ガスを流し始め、そのまま室温まで冷却した。 When the supply time of the HCl gas reached 30 minutes, the HCl gas was stopped, and the temperature of the base substrate was lowered to 300 ° C. while continuously flowing the H 2 gas and the NH 3 gas. When the temperature of the base substrate reached 300 ° C., the H 2 gas and the NH 3 gas were stopped, and the N 2 gas was started to flow and cooled to room temperature as it was.
第１〜第３ステップのＧａＮの結晶成長により、図９に示すように、下地基板上には、小三角ファセット構造及び大三角ファセット構造並びに第１及び第２厚膜成長層を含む表面が平坦なＧａＮ層が形成された。なお、第１ステップの結晶成長条件は、小三角ファセット構造及び大三角ファセット構造の形成に好適なものであり、第２及び第３ステップの結晶成長条件は、第１及び第２厚膜成長層の形成による表面の平坦化に好適なものである。 Due to the crystal growth of GaN in the first to third steps, as shown in FIG. 9, the surface including the small triangular facet structure and the large triangular facet structure and the first and second thick film growth layers is flat on the substrate. GaN layer was formed. The crystal growth conditions in the first step are suitable for forming a small triangular facet structure and a large triangular facet structure, and the crystal growth conditions in the second and third steps are the first and second thick film growth layers. It is suitable for flattening the surface by forming the above.
＜実施例２＞
図７Ｂに示すように、短周期マスク１３の幅ｗ２を５μｍ及び短周期マスク１３間の間隔Ｗ２を３６μｍとし、長周期マスク１２間の間隔Ｗ１を短周期マスク１３で５等分に分割した下地基板１０を用いたことを除いて実施例１と同様にしてＧａＮ層を形成した。
<Example 2>
As shown in FIG. 7B, the width w 2 of the short cycle mask 13 is 5 μm, the interval W 2 between the short cycle masks 13 is 36 μm, and the interval W 1 between the long cycle masks 12 is divided into 5 equal parts by the short cycle mask 13. A GaN layer was formed in the same manner as in Example 1 except that the divided base substrate 10 was used.
＜実施例３＞
図７Ｃに示すように、短周期マスク１３の幅ｗ２を４μｍ及び短周期マスク１３間の間隔Ｗ２を４７μｍとし、長周期マスク１２間の間隔Ｗ１を短周期マスク１３で４等分に分割した下地基板１０を用いたことを除いて実施例１と同様にしてＧａＮ層を形成した。
<Example 3>
As shown in FIG. 7C, the width w 2 of the short cycle mask 13 is 4 μm, the interval W 2 between the short cycle masks 13 is 47 μm, and the interval W 1 between the long cycle masks 12 is divided into four equal parts by the short cycle mask 13. A GaN layer was formed in the same manner as in Example 1 except that the divided base substrate 10 was used.
＜比較例＞
長周期マスクのみを設け、短周期マスクを設けていない下地基板を用いたことを除いて実施例１〜３と同様にしてＧａＮ層を形成した。この比較例では、第１〜第３ステップのＧａＮの結晶成長により、下地基板上には、大三角ファセット構造並びに第１及び第２厚膜成長層を含む表面が平坦なＧａＮ層が形成された。
<Comparison example>
The GaN layer was formed in the same manner as in Examples 1 to 3 except that a base substrate provided with only a long-period mask and no short-period mask was used. In this comparative example, by the crystal growth of GaN in the first to third steps, a large triangular facet structure and a GaN layer having a flat surface including the first and second thick film growth layers were formed on the base substrate. ..
（転位密度の分布）
実施例１〜３及び比較例のそれぞれで得られたＧａＮ層の表面について、図１０に示すように、長周期マスク１２の１ピッチ分の６０μｍ幅の部分を、長周期マスクの幅方向に５等分に分割し、各々、２１μｍ×６０μｍの長方形のＡ領域、Ｂ領域、Ｃ領域、Ｄ領域、及びＥ領域とした。そして、Ａ〜Ｅ領域のそれぞれについて、表面のＣＬ像の暗点密度から転位密度を求めた。また、Ａ〜Ｅ領域の平均転位密度を算出した。
(Dislocation density distribution)
Regarding the surfaces of the GaN layers obtained in Examples 1 to 3 and Comparative Examples, as shown in FIG. 10, a portion having a width of 60 μm for one pitch of the long-period mask 12 is 5 in the width direction of the long-period mask. It was divided into equal parts to obtain a rectangular A region, B region, C region, D region, and E region of 21 μm × 60 μm, respectively. Then, the dislocation density was obtained from the scotoma density of the CL image on the surface for each of the regions A to E. In addition, the average dislocation density in the regions A to E was calculated.
図１１は、Ａ〜Ｅ領域での転位密度の分布を示す。これによれば、図７Ａ〜Ｃに示すような基板本体１１上に長周期マスク１２及び短周期マスク１３を設けた下地基板１０を用い、小三角ファセット構造及び大三角ファセット構造を形成してＧａＮ層を構成した実施例１〜３では、Ａ〜Ｅ領域間に転位密度の大きなばらつきは認められず、したがって、転位が分散していることが分かる。一方、基板本体上に長周期マスクのみを設けた下地基板を用い、大三角ファセット構造のみを形成してＧａＮ層を構成した比較例では、Ａ〜Ｅ領域間に転位密度の大きなばらつきが認められ、転位が偏在していることが分かる。 FIG. 11 shows the distribution of dislocation densities in the regions A to E. According to this, a small triangular facet structure and a large triangular facet structure are formed by using a base substrate 10 provided with a long cycle mask 12 and a short cycle mask 13 on a substrate main body 11 as shown in FIGS. 7A to 7C, and GaN. In Examples 1 to 3 in which the layers were formed, no large variation in the dislocation density was observed between the regions A to E, and therefore, it can be seen that the dislocations were dispersed. On the other hand, in a comparative example in which only a large triangular facet structure was formed to form a GaN layer using a base substrate provided with only a long-period mask on the substrate body, a large variation in dislocation density was observed between the A to E regions. , It can be seen that the dislocations are unevenly distributed.
表２は、実施例１〜３及び比較例の平均転位密度を示す。これによれば、実施例１〜３の方が比較例よりも平均転位密度が低く、したがって、実施例１〜３では、転位が分散しているのに加えて、全体として低転位化されていることが分かる。 Table 2 shows the average dislocation densities of Examples 1 to 3 and Comparative Examples. According to this, the average dislocation density of Examples 1 to 3 is lower than that of Comparative Example. Therefore, in Examples 1 to 3, in addition to the dislocations being dispersed, the dislocations are lowered as a whole. You can see that there is.
本発明は、半導体基板の製造方法及びそれに用いる下地基板の技術分野について有用である。 The present invention is useful for a method for manufacturing a semiconductor substrate and a technical field of a base substrate used therein.
１０ 下地基板
１１ 基板本体
１２ 長周期マスク
１３ 短周期マスク
２０ ＧａＮ層
２１ 小三角ファセット構造
２２ 大三角ファセット構造
２３ 第１厚膜成長層
２４ 第２厚膜成長層
10 Base substrate 11 Substrate body 12 Long-period mask 13 Short-period mask 20 GaN layer 21 Small triangular facet structure 22 Large triangular facet structure 23 First thick film growth layer 24 Second thick film growth layer
Claims (7)
各々、前記複数の小三角ファセット構造のうちの２以上を取り込むとともに、前記所定方向に沿った断面形状が相対的に大きい三角形を構成するように前記半導体が結晶成長した複数の大三角ファセット構造を、それらが前記所定方向に並んで配設されるように形成するステップと、
を含む半導体基板の製造方法。 A step of forming a plurality of small triangular facet structures in which semiconductors are crystal-grown so as to form a triangle having a relatively small cross-sectional shape along a predetermined direction, so that they are arranged side by side in the predetermined direction. When,
Each of the plurality of small triangular facet structures incorporates two or more of the plurality of small triangular facet structures, and a plurality of large triangular facet structures in which the semiconductor is crystal-grown so as to form a triangle having a relatively large cross-sectional shape along the predetermined direction. , And the step of forming them so as to be arranged side by side in the predetermined direction.
A method for manufacturing a semiconductor substrate including.
前記複数の大三角ファセット構造のそれぞれの斜めファセット面から、前記半導体がエピタキシャルラテラル成長して相互に隣接する前記大三角ファセット構造間の凹部を埋め込むように第１厚膜成長層を形成するステップと、
前記複数の大三角ファセット構造のそれぞれの上に、前記所定方向に沿った断面形状が逆三角形を構成するように前記半導体が前記大三角ファセット構造の底面と同一の結晶成長面で結晶成長した第２厚膜成長層を形成するステップと、
を更に含み、
前記複数の大三角ファセット構造の上の複数の前記第２厚膜成長層が合体することにより前記第１厚膜成長層を埋設する半導体基板の製造方法。 In the method for manufacturing a semiconductor substrate according to claim 1,
A step of forming a first thick film growth layer from each oblique facet surface of the plurality of large triangular facet structures so that the semiconductor grows epitaxially laterally and embeds recesses between the large triangular facet structures adjacent to each other. ,
On each of the plurality of large triangular faceted structures, the semiconductor is crystal-grown on the same crystal growth plane as the bottom surface of the large triangular faceted structure so that the cross-sectional shape along the predetermined direction forms an inverted triangle. 2 Steps to form a thick film growth layer,
Including
A method for manufacturing a semiconductor substrate in which a first thick film growth layer is embedded by coalescing a plurality of the second thick film growth layers on the plurality of large triangular facet structures.
前記半導体がＧａＮである半導体基板の製造方法。 In the method for manufacturing a semiconductor substrate according to claim 1 or 2.
A method for manufacturing a semiconductor substrate in which the semiconductor is GaN.
基板本体と
前記基板本体上に一定周期で間隔をおいて設けられた複数の長周期マスクと、
前記基板本体上における相互に隣接する前記長周期マスク間に一定周期で間隔をおいて設けられた前記長周期マスクとは構成の異なる複数の短周期マスクと、
を備えた下地基板。 A base substrate used for manufacturing a semiconductor substrate.
A plurality of long-period masks provided on the substrate body and the substrate body at regular intervals,
A plurality of short-period masks having a configuration different from that of the long-period masks provided at regular intervals between the long-period masks adjacent to each other on the substrate main body,
Substrate with.
前記基板本体上に前記複数の長周期マスク及び前記複数の短周期マスクがストライプ状に設けられている下地基板。 In the base substrate according to claim 4,
A base substrate on which the plurality of long-period masks and the plurality of short-period masks are provided in a stripe shape on the substrate main body.
前記基板本体上に、前記長周期マスクが、平面視で相対的に大きい複数の六角形を形成するように設けられているとともに、前記短周期マスクが、前記長周期マスクの各六角形内に、平面視で相対的に小さい複数の六角形を形成するように設けられており、前記複数の長周期マスク及び前記複数の短周期マスクが、前記基板本体上に、三方向にストライプ状に設けられた下地基板。 In the base substrate according to claim 4,
The long-period mask is provided on the substrate body so as to form a plurality of hexagons that are relatively large in a plan view, and the short-period mask is placed in each hexagon of the long-period mask. , The plurality of hexagons that are relatively small in a plan view are provided, and the plurality of long-period masks and the plurality of short-period masks are provided on the substrate main body in a stripe shape in three directions. Base substrate.
前記短周期マスクは、その幅が前記長周期マスクとは構成が異なる下地基板。 In the base substrate according to any one of claims 4 to 6,
The short-period mask is a base substrate whose width is different from that of the long-period mask.
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