AIN crystal and method for growing the same, and AIN crystal substrate

[0033] Embodiment 1

[0034] This embodiment is characterized in that, with reference to FIGS. 1 and 2 , the carbon produced by the graphite crucible (the crystal growth vessel 12 ) forming the inner wall of the carbon-containing gas production chamber 23 and by the AlN source 1 placed in the crystal growth chamber 24 is produced. The carbon-containing gas produced by the reaction between the AlN gas sources is supplied to the inside of the crystal growth chamber 24 .

[0035] In this embodiment, referring to FIG. 2 , a crystal growth chamber 24 with a high temperature resistant material 21 as a wall and a carbon-containing gas production chamber 23 with a high temperature resistant material 21 and a crystal growth vessel 12 as walls are formed in the crystal growth vessel 12 (graphite crucible). Here, air circulates through the crystal growth chamber 24 and the carbon-containing gas production chamber 23 via the opening portion 21h; Here, the crystal growth chamber 24 communicates with the carbon-containing gas production chamber 23 via the opening portion 21h for ventilation; and the carbon-containing gas production chamber 23 communicates with the outside of the crystal growth vessel 12 via the opening portions 12h, 13a, and 13b for ventilation.

[0036] In the present embodiment, referring to FIGS. 1 and 2, the AlN source 1 is placed at one end of the crystal growth chamber 24 where the opening 21h exists, and the seed crystal substrate 2 is placed at the other end, while inside the reaction chamber 11 (crystal growth By heating the crystal growth vessel 12, the carbon-containing gas production chamber 23, and the crystal growth chamber 24 under a high temperature (for example, a temperature of about 1700°C to 2300°C) atmosphere with nitrogen gas supplied as a carrier gas, the outside of the vessel 12) The AlN gas source is generated from the AlN source 1 placed in the crystal growth chamber 24 . The AlN gas source enters the carbon-containing gas production chamber 23 via the opening portion 21h, and reacts with carbon in the graphite of the crystal growth vessel 12 (graphite crucible) forming the inner wall 12s of the carbon-containing gas production chamber 23 to generate carbon-containing gas. and N entering the crystal growth vessel 12 from outside the crystal growth vessel 12 via the openings 13a, 13b, 12h 2 Along with the (nitrogen) gas, the carbon-containing gas is supplied to the crystal growth chamber 24 via the opening 21h. The carbon-containing gas is supplied to the inside of the crystal growth chamber 24 in such a manner that the carbon-containing gas in the AlN crystal growth in the crystal growth chamber 24 becomes above a predetermined amount. In addition, changing the diameter of the opening 21h can increase and decrease the amount of carbon-containing gas supplied to the crystal growth chamber 24 . That is, as the diameter of the opening portion 21h is increased, the amount of the carbon-containing gas supplied to the inside of the crystal growth chamber 24 is increased.

[0037] In the crystal growth chamber 24 , sublimation of the AlN source 1 produces an AlN gas source, and solidification of the AlN gas source results in the growth of AlN crystals 4 on the seed substrate 2 . In this crystal growth, the carbon-containing gas supplied to the crystal growth chamber 24 eliminates a crystal non-growth region (not shown) on the seed substrate 2 , and the AlN crystal 4 grows across the front surface of the seed substrate 2 . As a result, large-diameter-span AlN crystals with good crystallinity can be obtained.

[0038] Embodiment 2

[0039] The present embodiment is characterized in that, with reference to FIGS. 1 and 3 , carbon in the graphite crucible (crystal growth vessel 12 ) forming the inner wall of the carbon-containing gas production chamber 23 and by metal oxide placed in the carbon-containing gas production chamber 23 3 CO gas and/or CO generated by the reaction between the generated metal oxide gases 2 , is supplied to the inside of the crystal growth chamber 24 as a carbon-containing gas.

[0040] In this embodiment, referring to FIG. 3 , as in Embodiment 1, a crystal growth chamber 24 having a high temperature resistant material 21 as a wall, and a carbon-containing gas production chamber having a high temperature resistant material 21 and a crystal growth vessel 12 as walls 23. Formed in the crystal growth vessel 12 (graphite crucible). Here, air circulates through the crystal growth chamber 24 and the carbon-containing gas production chamber 23 via the opening portion 21h, and circulates through the outside of the carbon-containing gas production chamber 23 and the crystal growth vessel 12 via the opening portions 12h, 13a, 13b. Here, for ventilation, the crystal growth chamber 24 communicates with the carbon-containing gas production chamber 23 via the opening portion 21h, and for ventilation, the carbon-containing gas production chamber 23 communicates with the outside of the crystal growth vessel 12 via the opening portions 12h, 13a, and 13b .

[0041] This embodiment mode is similar to Embodiment Mode 1 in that with reference to FIGS. 1 and 3 , the AlN source 1 is placed at one end of the crystal growth chamber 24 where the opening portion 21h exists, and the seed substrate 2 is placed at the opposite side of the crystal growth chamber 24. There is an end opposite to one end of the opening portion 21 h ; and this embodiment is different from Embodiment 1 in that the metal oxide 3 is further placed in the carbon-containing gas production chamber 23 . Here, the metal oxide is not particularly limited as long as it reacts with carbon to generate CO gas and/or CO 2 Metal oxides of gases, but produced from CO gas and/or CO 2 gas without adversely affecting the crystallinity of AlN crystals, Al 2 O 3 is a preferred example of the metal oxide.

[0042] While nitrogen gas is supplied as a carrier gas to the reaction chamber 11 (outside of the crystal growth vessel 12 in FIG. 3), the crystal growth vessel 12, the carbon-containing gas production chamber 23 and the crystal growth chamber 24 are heated, as a result, at a high temperature (eg, , a temperature of about 1700° C. to 2300° C.) atmosphere, the metal oxide gas is generated from the metal oxide 3 placed in the carbon-containing gas production chamber 23 . This metal oxide gas reacts with carbon in the graphite of the crystal growth vessel 12 (graphite crucible) forming the inner wall 12s of the carbon-containing gas production chamber 23 to generate CO gas and/or CO 2 gas as carbon-containing gas. and N entering the crystal growth vessel 12 from the outside of the crystal growth vessel 12 via the opening portions 13a, 13b and 12h 2 (nitrogen) gas together, CO gas and/or CO 2 The gas is supplied to the crystal growth chamber 24 via the opening portion 21h. In this way the CO gas and/or CO 2 The gas is supplied to the inside of the crystal growth chamber 24 so that CO gas and/or CO in the crystal growth chamber 24 during AlN crystal growth 2 The gas reaches a predetermined amount or more. In addition, changing the diameter of the opening portion 21h can increase and decrease the CO gas and/or CO supplied to the inside of the crystal growth chamber 24 2 amount of gas. That is, lengthening the diameter of the opening portion 21h increases the supply of CO gas and/or CO to the inside of the crystal growth chamber 24 2 amount of gas.

[0043] In the crystal growth chamber 24 , the sublimation of the AlN material 1 produces a source of AlN gas, and the solidification of the AlN gas source results in the growth of AlN crystals 4 on the seed substrate 2 . In this crystal growth, the CO gas and/or CO supplied to the inside of the crystal growth chamber 24 2 The gas eliminates crystal non-growth regions (not shown) on the seed substrate 2 , and AlN crystals 4 grow across the front side of the seed substrate 2 . As a result, large-diameter-span AlN crystals with good crystallinity can be obtained.

[0044] Embodiment 3

[0045] This embodiment mode is a mode by which the carbon-containing gas is supplied directly from the outside of the reaction chamber 11 to the inside of the crystal growth chamber 24 in the crystal growth vessel provided in the reaction chamber 11 . Here, in order to control the carbon content in the gas supplied to the inside of the crystal growth chamber 4, the carbon-containing gas is supplied together with the carrier gas. As carrier gas, use N which does not react with carbon-containing gases 2 (nitrogen) gas and other gases. In addition, there is no specific limitation on the carbon-containing gas, but it is preferable to use CO gas and/or from the viewpoint of eliminating regions on the seed substrate 2 where crystals do not grow to efficiently grow large-diameter-span AlN crystals with good crystallinity or CO 2 gas. In the present embodiment, referring to FIG. 4 , a crystal growth chamber 24 with a high temperature resistant material 13 as a wall is formed in the crystal growth vessel 12 (which may not be a graphite crucible). For ventilation, the crystal growth chamber 24 communicates with the outside of the crystal growth vessel 12 via the opening portions 21h, 12h, 13a and 13b.

[0046] In this embodiment mode, referring to FIGS. 1 and 4 , in the case where the AlN source 1 is placed at one end of the crystal growth chamber 24 where the opening portion 21h exists, and the seed substrate 2 is placed at the other end, the N 2 gas, and CO gas or CO 2 The gas is supplied to the inside of the reaction chamber 11 (the outside of the crystal growth vessel 12 in FIG. 3 ). provided N 2 Gas and CO gas or CO 2 The gas is supplied to the inside of the crystal growth chamber 24 via the opening portions 13a, 13b, 12h, and 21h.

[0047] In the crystal growth chamber 24 , sublimation of the AlN source 1 produces an AlN gas source, and solidification of the AlN gas source results in the growth of AlN crystals 4 on the seed substrate 2 . In this crystal growth, CO gas or CO supplied to the inside of the crystal growth chamber 24 2 The gas eliminates crystal non-growth regions (not shown) on the seed substrate 2 , and AlN crystals 4 grow across the front side of the seed substrate 2 . As a result, large-diameter-span AlN crystals with good crystallinity can be obtained.