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US-12628397-B2 - Nitride semiconductor with multiple nitride regions of different impurity concentrations, wafer, semiconductor device and method for manufacturing the same

US12628397B2US 12628397 B2US12628397 B2US 12628397B2US-12628397-B2

Abstract

According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region including Al x1 Ga 1-x1 N (0<x1≤1), a second nitride region including Al x2 Ga 1-x2 N (0<x2<1, x2<x1), and a third nitride region. The second nitride region is between the first nitride region and the third nitride region. The third nitride region includes Al, Ga, and N. The third nitride region does not include carbon, alternately a third carbon concentration in the third nitride region is lower than a second carbon concentration in the second nitride region.

Inventors

  • Toshiki Hikosaka
  • Hajime Nago
  • Jumpei Tajima
  • Shinya Nunoue

Assignees

  • KABUSHIKI KAISHA TOSHIBA

Dates

Publication Date
20260512
Application Date
20231116
Priority Date
20201211

Claims (16)

  1. 1 . A nitride semiconductor, comprising: a nitride member, the nitride member including: a first nitride region including Al x1 Ga 1-x1 N (0<x1≤1); a second nitride region including Al x2 Ga 1-x2 N (0<x2<1, x2<x1), the second nitride region including carbon; and a third nitride region, the second nitride region being between the first nitride region and the third nitride region, the third nitride region including Al, Ga, and N, the third nitride region not including carbon, alternatively a third carbon concentration in the third nitride region being lower than a second carbon concentration in the second nitride region, wherein the third nitride region includes a plurality of first regions and a plurality of second regions, in a first direction from the first nitride region to second nitride region, one of the plurality of first regions is between one of the plurality of second regions and another one of the plurality of second regions, the one of the plurality of second regions is between the one of the plurality of first regions and another one of the plurality of first regions, the first region includes Al y1 Ga 1-y1 N (0<y1≤1), the second region includes Al y2 Ga 1-y2 N (0≤y2<y1), a first region thickness along the first direction of each of the plurality of first regions is thinner than a second nitride region thickness along the first direction of the second nitride region, and a second region thickness along the first direction of each of the plurality of second regions is thinner than the second nitride region thickness.
  2. 2 . The nitride semiconductor according to claim 1 , wherein the second carbon concentration is not less than 1×10 19 /cm 3 and not more than 8×10 19 /cm 3 .
  3. 3 . The nitride semiconductor according to claim 1 , wherein the second nitride region does not include oxygen, alternatively a second oxygen concentration in the second nitride region is lower than a third oxygen concentration in the third nitride region.
  4. 4 . The nitride semiconductor according to claim 3 , wherein the second nitride region includes oxygen, and the second oxygen concentration is not more than 4×10 16 /cm 3 .
  5. 5 . The nitride semiconductor according to claim 1 , wherein x2 is not less than 0.08 and not more than 0.28.
  6. 6 . The nitride semiconductor according to claim 1 , wherein an Al composition ratio in the third nitride region is higher than an Al composition ratio in the second nitride region, and lower than an Al composition ratio in the first nitride region.
  7. 7 . The nitride semiconductor according to claim 6 , wherein an Al composition ratio in the third nitride region is not less than 0.18 and not more than 0.38.
  8. 8 . The nitride semiconductor according to claim 1 , wherein y2 is higher than x2.
  9. 9 . The nitride semiconductor according to claim 1 , wherein y1 is not more than x1.
  10. 10 . The nitride semiconductor according to claim 1 , wherein a first region thickness along the first direction of each of the plurality of first regions is thinner than a first nitride region thickness along the first direction of the first nitride region, and a second region thickness along the first direction of each of the plurality of second regions is thinner than the first nitride region thickness.
  11. 11 . The nitride semiconductor according to claim 1 , wherein each of the plurality of first regions has a first region thickness t1 along the first direction, each of the plurality of second regions has a second region thickness t2 along the first direction, and x2, t1, t2, y1 and y2 satisfy x 2<{( y 1· t 1+ y 2· t 2)/( t 1+ t 2)}.
  12. 12 . The nitride semiconductor according to claim 11 , wherein each of the plurality of first regions has a first region thickness t1 along the first direction, each of the plurality of second regions has a second region thickness t2 along the first direction, and x2, t1, t2, y1 and y2 satisfy {( y 1· t 1+ y 2· t 2)/( t 1+ t 2)}.
  13. 13 . The nitride semiconductor according to claim 1 , further comprising: a substrate, the first nitride region being between the substrate and the third nitride region.
  14. 14 . A nitride semiconductor, comprising: a nitride member, the nitride member including: a first nitride region including Al x1 Ga 1-x1 N (0<x≤1); a second nitride region including Al x2 Ga 1-x2 N (0<x2<1, x2<x1), the second nitride region including carbon; a third nitride region, the second nitride region being between the first nitride region and the third nitride region, the third nitride region including Al, Ga, and N, the third nitride region not including carbon, alternatively a third carbon concentration in the third nitride region being lower than a second carbon concentration in the second nitride region, a fourth nitride region including Al x4 Ga 1-x4 N (0≤x4<1), and a fifth nitride region including Al x5 Ga 1-x5 N (0≤x5<1, x4<x5), wherein the third nitride region is between the first nitride region and the fifth nitride region, the fourth nitride region is between the third nitride region and the fifth nitride region, the fourth nitride region includes a first film region and a second film region, the first film region is between the third nitride region and the second film region, the first film region includes carbon, and the second film region does not include carbon, alternatively a carbon concentration in the second film region is lower than a carbon concentration in the first film region.
  15. 15 . A wafer, comprising: the nitride semiconductor according to claim 1 ; and a substrate, the first nitride region being between the substrate and the third nitride region.
  16. 16 . A semiconductor device, comprising: a nitride semiconductor; a first electrode; a second electrode; a third electrode; and an insulating member, the nitride semiconductor comprising: a nitride member, the nitride member including: a first nitride region including Al x1 Ga 1-x N (0<x1≤1); a second nitride region including Al x2 Ga 1-2x N (0<x2<1, x2<x1), the second nitride region including carbon; a third nitride region, the second nitride region being between the first nitride region and the third nitride region, the third nitride region including Al, Ga, and N, the third nitride region not including carbon, alternatively a third carbon concentration in the third nitride region being lower than a second carbon concentration in the second nitride region, a fourth nitride region including Al x4 Ga 1-x4 N (0≤x4<1), and a fifth nitride region including Al x5 Ga 1-x5 N (0≤x5<1, x4<x5), the third nitride region being between the first nitride region and the fifth nitride region, and the fourth nitride region being between the third nitride region and the fifth nitride region, a direction from the first electrode to the second electrode being along a second direction crossing a first direction from the first nitride region to second nitride region, a position of the third electrode in the second direction being between a position of the first electrode in the second direction and a position of the second electrode in the second direction, the fourth nitride region including a first partial region, a second partial region, a third partial region, a fourth partial region, and a fifth partial region, a direction from the first partial region to the first electrode being along the first direction, a direction from the second partial region to the second electrode being along the first direction, the third partial region being between the first partial region and the second partial region in the second direction, a direction from the third partial region to the third electrode being along the first direction, the fourth partial region being between the first partial region and the third partial region in the second direction, the fifth partial region being between the third partial region and the second partial region in the second direction, the fifth nitride region including a sixth partial region and a seventh partial region, a direction from the fourth partial region to the sixth partial region being along the first direction, a direction from the fifth partial region to the seventh partial region being along the first direction, and the insulating member being between the nitride member and the third electrode.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of and claims benefit under 35 U.S.C. § 120 to U.S. application Ser. No. 17/305,470, filed Jul. 8, 2021, and claims the benefit of priority under 35 U.S.C. § 119 from Japanese Patent Application No. 2020-205601 filed Dec. 11, 2020, the entire contents of each of which are incorporated herein by reference. FIELD Embodiments described herein relate generally to a nitride semiconductor, a wafer, a semiconductor device and a method for manufacturing the nitride semiconductor. BACKGROUND For example, improvement of characteristics is desired in a semiconductor device based on a nitride semiconductor. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating a nitride semiconductor according to a first embodiment; FIG. 2 is a graph view illustrating characteristics of the nitride semiconductor; FIG. 3 is a graph view illustrating characteristics of the nitride semiconductor; FIG. 4 is a schematic cross-sectional view illustrating the nitride semiconductor according to the first embodiment; FIG. 5 is a graph view illustrating the nitride semiconductor according to the first embodiment; FIGS. 6A and 6B are graph views illustrating the nitride semiconductor according to the first embodiment; FIG. 7 is a schematic view illustrating the nitride semiconductor according to the first embodiment; FIG. 8 is a graph view illustrating characteristics of the nitride semiconductor; FIG. 9 is a schematic cross-sectional view illustrating a semiconductor device according to a third embodiment; FIG. 10 is a schematic cross-sectional view illustrating a semiconductor device according to the third embodiment; and FIG. 11 is a flow chart illustrating a method for manufacturing a nitride semiconductor according to a fourth embodiment. DETAILED DESCRIPTION According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region including Alx1Ga1-x1N (0<x1≤1), a second nitride region including Alx2Ga1-x2N (0<x2<1, x2<x1), and a third nitride region. The second nitride region is between the first nitride region and the third nitride region. The third nitride region includes Al, Ga, and N. The third nitride region does not include carbon, alternately a third carbon concentration in the third nitride region is lower than a second carbon concentration in the second nitride region. According to one embodiment, a wafer includes the nitride semiconductor described above and a substrate. The first nitride region is between the substrate and the third nitride region. According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region including Alx1Ga1-x1N (0<x1≤1), a second nitride region including Alx2Ga1-x2N (0<x2<1, x2<x1), and a third nitride region. The second nitride region is between the first nitride region and the third nitride region. The third nitride region includes Al, Ga, and N. The third nitride region does not include carbon, alternately a third carbon concentration in the third nitride region is lower than a second carbon concentration in the second nitride region. The nitride member further includes a fourth nitride region including Alx4Ga1-x4N (0≤x4<1), and a fifth nitride region including Alx5Ga1-x5N (0≤x5<1, x4<x5), The third nitride region is between the first nitride region and the fifth nitride region. The fourth nitride region is between the third nitride region and the fifth nitride region. According to one embodiment, a method for manufacturing a nitride semiconductor is disclosed. The method can include forming a second nitride region including Alx2Ga1-x2N (0<x2<1, x2<x1) and including carbon on a first nitride region including Alx1Ga1-x1N (0<x1≤1). The method can include forming a third nitride region on the second nitride region. The third nitride region includes Al, Ga, and N. The third nitride region does not include carbon, alternately a third carbon concentration in the third nitride region is lower than a second carbon concentration in the second nitride region. Various embodiments are described below with reference to the accompanying drawings. The drawings are schematic and conceptual; and the relationships between the thickness and width of portions, the proportions of sizes among portions, etc., are not necessarily the same as the actual values. The dimensions and proportions may be illustrated differently among drawings, even for identical portions. In the specification and drawings, components similar to those described previously or illustrated in an antecedent drawing are marked with like reference numerals, and a detailed description is omitted as appropriate. First Embodiment FIG. 1 is a schematic cross-sectional view illustrating a nitride semiconductor according to a first embodiment. As shown in FIG. 1, the nitride semiconductor 110 according to the embodiment includes a ni