Method of separating surface layer of semiconductor crystal using a laser beam perpendicular to the separating plane

Abstract

This invention provides two variations of methods of separating a surface layer of the semiconductor crystal. In the second variation of the method, pulse laser emission is generated; a focused laser beam is directed onto the crystal in such a way that focus is placed in the layer separation plane perpendicular the axis of the beam, a laser beam is moved in such a way that focus is moved in the layer separation plane with forming the non-overlapping local regions with a disturbed topology of the crystal structure and with reduced interatomic bonds, wherein the local regions is distributed over the whole plane, an external action disturbing the reduced interatomic bonds is applied to the separable layer. The invention allows separating flat lateral surface layers from semiconductor crystals, and thin semiconductor washes from cylindrical semiconductor boules.

Claims

1. A method of separating a surface layer of a monolithic semiconductor crystal or crystal boule, the monolithic semiconductor crystal or crystal boule having a top surface and a bottom surface, the method comprising: generating a pulsed laser beam having a wavelength λ in a range of 2πch/E.sub.g, ≤λ≤c/v.sub.0, wherein E.sub.g, is a forbidden gap for the monolithic semiconductor crystal or crystal boule, v.sub.0 is a frequency of an optical phonon for the monolithic semiconductor crystal or crystal boule, c is a velocity of light and h is a Plank constant; directing the pulsed laser beam onto the top surface the monolithic semiconductor crystal or crystal boule and focusing the pulsed laser beam such that a focus of the pulsed laser beam is placed in a separation plane perpendicular to an axis of the pulsed laser beam, the separation plane located intermediate the top surface and the bottom surface; moving the pulsed laser beam such that the focus of the pulsed laser beam is moved along an entirety of the separation plane while forming non-overlapping local regions in which structure of chemical bonds is disturbed, chemical interaction between atoms is reduced, and mechanical strength is decreased wherein the surface layer of the monolithic semiconductor crystal or crystal boule extends from the separation plane to the top surface; applying an external action to the surface layer, the external action destroying the reduced chemical interaction between atoms of the non-overlapping local regions, wherein the destroying causes complete separation of the surface layer of the monolithic semiconductor crystal or crystal boule along the separation plane.

2. The method according to claim 1, wherein the external action is a mechanical action.

3. The method according to claim 2, wherein the mechanical action is a mechanical stress applied to the surface layer in relation to the monolithic semiconductor crystal or crystal boule.

4. The method according to claim 1, wherein a distance between the centers of the non-overlapping local regions is 3%-30% of a thickness of the surface layer.

5. The method according to claim 1, wherein the surface layer of the monolithic semiconductor crystal or crystal boule contains grown in layered semiconductor device structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) This invention is illustrated by the drawings, FIG. 1 and FIG. 2 show prior art and FIGS. 3-14 show various embodiments of this invention.

(2) FIG. 1 is a scheme illustrating the known prior art method of vertical laser cutting of semiconductor crystal using a high focused laser emission leading to a thermal chemical decomposition or evaporation of the crystal in the vicinity of the laser beam focus.

(3) FIG. 2 is a scheme illustrating the known prior art method of vertical laser cutting of semiconductor crystal using a focused pulse laser emission creating the local regions in the vertical plane.

(4) FIG. 3 is a scheme illustrating the first variation of the method of separating a surface layer of the semiconductor crystal.

(5) FIG. 4 is a scheme illustrating the first variation of the method of separating a thin semiconductor layer comprising a grown instrument structure under its upper surface, from the semiconductor crystal.

(6) FIG. 5 is a scheme illustrating the first variation of the method of separating a thin semiconductor layer comprising a grown instrument structure in its base, from the semiconductor crystal.

(7) FIG. 6 is a scheme illustrating the second variation of the method of separating a surface layer of the semiconductor crystal.

(8) FIG. 7 is a scheme illustrating the second variation of the method of separating a thin semiconductor layer comprising a grown instrument structure under its upper surface, from the semiconductor crystal.

(9) FIG. 8 is a scheme illustrating the second variation of the method of separating a thin semiconductor layer comprising a grown instrument structure in the base, from the semiconductor crystal.

(10) FIG. 9 is a scheme illustrating the first variation of the method of separating a surface layer of the semiconductor boule into semiconductor washers.

(11) FIG. 10 is a scheme illustrating the first variation of the method of separating a thin semiconductor washer comprising a grown instrument structure under its upper surface, from the semiconductor boules.

(12) FIG. 11 is a scheme illustrating the first variation of the method of separating a thin semiconductor washer comprising a grown instrument structure in the base, from the semiconductor boules.

(13) FIG. 12 is a scheme illustrating the second variation of the method of separating a surface layer of the semiconductor boules into semiconductor washers.

(14) FIG. 13 is a scheme illustrating the second variation of the method of separating a thin semiconductor washer comprising a grown instrument structure under its upper surface, from the semiconductor boules.

(15) FIG. 14 is a scheme illustrating the second variation of the method of separating a thin semiconductor washer, comprising a grown instrument structure in its base, from the semiconductor boules.

DETAILED DESCRIPTION

(16) The present invention will become readily apparent from the following detailed description of exemplary embodiments. It should be noted that the consequent description of these embodiments is only illustrative, but not exhaustive.

(17) For realizing the method, this invention uses laser emission of λ wavelength within the region of relative semiconductor transparency, namely between the edge of the main absorption and the region of the residual beams.

(18) Preferably, wavelength λ of the laser beam is in the range of 2 πcℏ/E.sub.g≤λ≤c/v.sub.0, where E.sub.g is a width of the forbidden gap for cutable semiconductor, v.sub.0 is a frequency of the optical phonon for cutable semiconductor, c is a velocity of light, ℏ is Plank constant.

(19) As follows from the above inequality, the preferred laser beam wavelength for lateral cutting of the silicon, germanium and gallium arsenide semiconductor is in the range of 0.8 μm≤λ≤20 μm, for gallium nitride it is in the range of 0.35 μm≤λ≤10 μm, and for aluminum nitride it is in the range of 0.2 μm≤λ≤8 μm.

Example 1

(20) FIG. 3 shows the scheme 300 illustrating the first variation of the method by the example of separating the surface layer of the gallium nitride semiconductor crystal. For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor, with frequency doubling and generates light pulses with λ=532 nm, energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 16 μm in diameter which provides energy density of 2 J/cm.sup.2.

(21) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal 101, focused under the upper crystal surface 105 at the depth of 100 μm, the crystal 101 is locally heated up to temperature higher than 900° C. leading to chemical decomposition of gallium nitride crystal 101 into gaseous nitrogen and liquid gallium in the vicinity 106 of the laser beam focus. Movement of the laser beam 102 focus at velocity of 1.5 cm/s in the horizontal (lateral) plane parallel to the crystal surface 105 through which laser beam enters the crystal 101, and perpendicular towards the axis 103 of the focused laser beam 102, lead to consequent decomposition of gallium nitride and to increase of width of the lateral cut 304 from left to right deep into the crystal 101. On achieving by the lateral cut 304 the right bound of the crystal in FIG. 3, continuity of the crystal 101 is disturbed and the upper layer 307 being higher than the cut 304 is separated from the main crystal 101. To avoid cracking of the gallium nitride crystal 101 caused by thermal stresses, laser cutting is performed at temperature T.sub.p=600° C.

Example 2

(22) FIG. 4 shows the scheme 400 illustrating the first variation of the method by the example of separating a thin semiconductor layer comprising a grown light diode structure AlGaN/InGaN/AlGaN under the upper surface, from semiconductor crystal. For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor, and generates light pulses with λ=532 nm, energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 16 μm in diameter which provides energy density of 2 J/cm.sup.2.

(23) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal 101 and in the light diode structure 407 AlGaN/InGaN/AlGaN, focused under the crystal surface 105 at the depth of 50 μm, the crystal 101 is locally heated up to temperature higher than 900° C. leading to chemical decomposition of gallium nitride crystal 101 into gaseous nitrogen and liquid gallium in the vicinity 106 of the laser beam focus. Movement of the laser beam 102 focus at velocity of 1.5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal 101, and perpendicular towards the axis 103 of the focused laser beam 102, leads to consequent decomposition of gallium nitride and to increase of width of the cut 304 in the horizontal plane from left to right deep into the crystal 101. On achieving by the lateral cut 304 the right bound of the crystal in FIG. 4, continuity of the crystal 101 is disturbed and the upper layer 307 with grown light diode structure 407 AlGaN/InGaN/AlGaN lying higher than the cut 304 is separated from the main crystal 101. To avoid cracking of the gallium nitride crystal caused by thermal stresses, laser cutting is performed at temperature T.sub.p=600° C.

Example 3

(24) FIG. 5 is a scheme 500 illustrating the first variation of the method by the example of separating a thin semiconductor layer comprising a grown light diode structure AlGaN/InGaN/AlGaN in the base, from semiconductor crystal.

(25) For this purpose, Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates pulses with energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 16 μm in diameter which provides energy density of 2 J/cm.sup.2. Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal 101, but absorbed in the light diode structure 407 AlGaN/InGaN/AlGaN, focused deeply under the upper crystal surface 105, the crystal 101 is locally heated up to temperature higher than 900° C. leading to the chemical decomposition of gallium nitride crystal 101 into gaseous nitrogen and liquid gallium in the vicinity 106 of the laser beam focus. Movement of the laser beam 102 focus at velocity of 1.5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal 101, and perpendicular towards the axis 103 of the focused laser beam 102, leads to consequent decomposition of gallium nitride and to increase of width of the cut 304 in the horizontal plane from left to right deep into the crystal 101. On achieving by the lateral cut 304 the right bound of the crystal in FIG. 5, continuity of the crystal 101 is disturbed and the lower layer 307 with grown light diode structure 407 AlGaN/InGaN/AlGaN lying lower than the cut 304 is separated from the main crystal 101.

Example 4

(26) FIG. 6 is a scheme 600 illustrating the second variation of the method by the example of separating the surface layer of the gallium arsenide semiconductor crystal. For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=1064 nm, and generates pulses with energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 2 μm in diameter which provides energy density of 2.5 J/cm.sup.2.

(27) Under action of the Nd:YAG laser beam 102 with wavelength λ=1064 nm weakly absorbed in the gallium arsenide crystal 101, focused under the upper crystal surface 105 at the depth of 100 μm, non-overlapping local regions 206 are formed in which structure of chemical bonds is disturbed, chemical interaction between atoms is reduced and mechanical strength of the crystal is decreased. Movement of the laser beam 102 focus at velocity of 1 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal 101, and perpendicular to the axis 103 of the focused laser beam 102, leads to formation of a set of non-overlapping local regions 206 in the plane 604 which is placed under the crystal surface 105 at the depth defined by focusing depth of the laser beam 102. The average distance between the local regions 206 equals 10 μm. When scanning and moving the focused laser beam 102 in the horizontal plane from left to right, area of the section plane 604 with a set of the local regions is increased from left to right deep into the crystal up to the right bound of the crystal 101 in FIG. 6. Laser treatment is performed at room temperature T.sub.p=20° C.

(28) At this point, the process of laser treatment is completed. Then crystal 101 is adhered with upper surface 105 on the aluminium plate and heated to the temperature of 100-500° C. In this case, because of thermomechanical stress related with difference between the thermal expansion coefficients of gallium arsenide and aluminium arsenide, crystal 101 splits along the mechanically reduced plane 604 with separating a surface lateral layer lying higher the plane 604 from the main gallium arsenide crystal.

Example 5

(29) FIG. 7 is the scheme 400 illustrating the second variation of the method by the example of separating a thin semiconductor layer comprising a grown light diode structure AlGaN/InGaN/AlGaN under the upper surface, from semiconductor crystal. For this purpose, Nd:YAG laser is used which operates in the mode of modulated Q-factor, and generates light pulses with λ=532 nm, energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 16 μm in diameter which provides energy density of 2 J/cm.sup.2.

(30) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal 101 and in light diode structure 407 AlGaN/InGaN/AlGaN, focused under the upper crystal surface 105 at the depth of 50 μm, non-overlapping local regions 206 are formed in which structure of chemical bonds is disturbed, chemical interaction between atoms is reduced and mechanical strength of the crystal 101 is decreased. Movement of the laser beam 102 focus at velocity of 5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal 101, and perpendicular to the axis 103 of the focused laser beam 102, leads to formation of a set of non-overlapping local regions 206 in the lateral separation plane 604 which is placed under the crystal surface 105 at the depth defined by focusing depth of the laser beam 102. The average distance between the local regions equals 5 μm. When scanning laser beam 102 with focus in the horizontal plane from left to right, area of the section plane 604 with a set of the local regions is increased from left to right deep into the crystal up to the right bound of the crystal 101 in FIG. 7. Laser treatment is performed at room temperature T.sub.p=20° C.

(31) At this point, the process of laser treatment is completed. Then crystal 101 is adhered with upper surface 105 on the aluminium plate and heated to the temperature of 100-500° C. In this case, because of thermomechanical stress related with difference between the thermal expansion coefficients of gallium nitride and aluminium nitride, the crystal 101 splits along the mechanically reduced plane 604 with separating a surface lateral layer 307 with light diode structure 407 AlGaN/InGaN/AlGaN lying higher the plane 604 from the main gallium nitride crystal 101.

Example 6

(32) FIG. 8 is a scheme 800 illustrating the second variation of the method by the example of separating a thin semiconductor layer comprising a grown light diode structure AlGaN/InGaN/AlGaN in the base, from semiconductor crystal.

(33) For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates pulses with energy of 50 μJ, duration of 5 ns and repetition rate of 10000 Hz. Laser beam is focused to the spot of 1 μm in diameter which provides energy density of 5 J/cm.sup.2.

(34) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal 101, but absorbed in the light diode structure 407 AlGaN/InGaN/AlGaN, focused deep under the upper crystal surface 105, non-overlapping local regions 206 are formed in which structure of chemical bonds is disturbed, chemical interaction between atoms is reduced and mechanical strength of the crystal is decreased. Movement of the laser beam 102 focus at velocity of 5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal 101, and perpendicular to the axis 103 of the focused laser beam 102, leads to formation of the non-overlapping local regions 206 in the lateral plane 604 which lies under the crystal surface 105 at the depth defined by the depth of the laser beam 102 focusing. The average distance between the local regions equals 5 μm. When scanning laser beam 102 with focus in the horizontal plane from left to right, area of the section plane 604 with a set of the local regions is increased from left to right deep into the crystal up to the right bound of the crystal 101 in FIG. 8. Laser treatment is performed at room temperature T.sub.p=20° C.

(35) At this point process of laser treatment is completed. Then crystal 101 is adhered with upper surface 105 on the aluminium plate and heated to the temperature of 100-500 C. In this case, because of thermomechanical stress related with difference between the thermal expansion coefficients of gallium nitride and aluminium nitride, crystal 101 splits along the mechanically reduced plane 604 with separating a lower lateral layer 307 with light diode structure AlGaN/InGaN/AlGaN lying lower the plane 604 from the main gallium nitride crystal.

Example 7

(36) FIG. 9 is a scheme 900 illustrating the first variation of the method by the example of separating a surface layer of the semiconductor cylindrical gallium nitride boule. For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates pulses with energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 16 μm in diameter which provides energy density of 2 J/cm.sup.2.

(37) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm focused under the surface 105 at the depth of 200 μm of the cylindrical gallium nitride boule 901, the crystal is locally heated up to temperature higher than 900° C. leading to chemical decomposition of gallium nitride crystal into gaseous nitrogen and liquid gallium in the vicinity 106 of the laser beam focus.

(38) Movement of the laser beam 102 focus on a spiral path at velocity of 1.5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal, and perpendicular to the axis 103 of the focused laser beam 102, leads to consequent decomposition of gallium nitride and to increase of width of the lateral cut 304 on a spiral path from periphery deep into the crystal towards the axis of the cylindrical boule 901. On achieving by the lateral cut 304 the axis of the cylindrical boule 901 in FIG. 9, continuity of the cylindrical gallium nitride boule 901 is disturbed and gallium nitride washer 902 being higher than the cut 304 is separated from the cylindrical gallium nitride boule 901. To avoid cracking of the separable gallium nitride washer 902 caused by thermal stresses, laser cutting is performed at temperature T.sub.p=600° C.

Example 8

(39) FIG. 10 is the scheme 1000 illustrating the first variation of the method by the example of separating a thin semiconductor washer comprising a grown light diode structure AlGaN/InGaN/AlGaN under the upper surface, from cylindrical semiconductor gallium nitrade boule. For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates light pulses with energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 16 μm in diameter which provides energy density of 2 J/cm.sup.2.

(40) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal and in light diode structure 407 AlGaN/InGaN/AlGaN, focused under the upper crystal surface 105 at the depth of 50 μm of the cylindrical boule 901, the crystal is locally heated up to temperature higher than 900° C. leading to chemical decomposition of gallium nitride crystal into gaseous nitrogen and liquid gallium in the vicinity 106 of the laser beam focus.

(41) Lateral movement of the laser beam 102 focus on a spiral path at velocity of 1.5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal, and perpendicular to the axis 103 of the focused laser beam 102, leads to consequent decomposition of gallium nitride and to increase of width of the lateral cut 304 on a spiral path from periphery deep into the crystal towards the axis of the cylindrical boule 901. On achieving by the lateral cut 304 the axis of the cylindrical boule 901 in FIG. 10, continuity of the cylindrical gallium nitride boule 901 is disturbed and gallium nitride washer 902 with a grown light diode structure 407 AlGaN/InGaN/AlGaN being higher the cut 304 is separated from the cylindrical gallium nitride boule 901. To avoid cracking of the separable gallium nitride washer 902 caused by thermal stresses, laser cutting is performed at temperature T.sub.p=600° C.

Example 9

(42) FIG. 11 is the scheme 1100 illustrating the first variation of the method by the example of separating a thin semiconductor washer comprising a grown light diode structure AlGaN/InGaN/AlGaN in the base, from cylindrical semiconductor gallium nitride boule.

(43) For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates light pulses with energy of 5 μJ, duration of 5 ns and repetition rate of 1000 Hz. Laser beam is focused to the spot of 16 μm in diameter which provides energy density of 2 J/cm.sup.2.

(44) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal, but absorbed in the light diode structure AlGaN/InGaN/AlGaN, focused deeply under the upper crystal surface 105 of the cylindrical gallium nitride boule 901, the crystal is locally heated up to temperature higher than 900° C. leading to the chemical decomposition of gallium nitride crystal into gaseous nitrogen and liquid gallium in the vicinity 106 of the laser beam focus. Movement of the laser beam 102 focus at velocity of 1.5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal, and perpendicular to the axis 103 of the focused laser beam 102, leads to consequent decomposition of gallium nitride and to increase of width of the lateral cut 304 on a spiral path from periphery deep into the crystal towards the axis of the cylindrical boule 901. On achieving by the lateral cut 304 the axis of the cylindrical boule 901 in FIG. 11, continuity of the cylindrical gallium nitride boule 901 is disturbed and gallium nitride washer 902 with grown light diode structure 507 AlGaN/InGaN/AlGaN lying lower the cut 304 is separated from the cylindrical gallium nitride boule 901.

Example 10

(45) FIG. 12 is a scheme 1200 illustrating the second variation of the method by the example of separating a washer from the semiconductor cylindrical boule of the aluminum nitride crystal. For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates pulses with energy of 50 μJ, duration of 5 ns and repetition rate of 10000 Hz. Laser beam is focused to the spot of 1 μm in diameter which provides energy density of 5 J/cm.sup.2.

(46) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm, focused under the surface 105 of cylindrical aluminium nitride boule 901 at the depth of 100 μm, non-overlapping local regions 206 are formed in which structure of chemical bonds is disturbed, chemical interaction between atoms is reduced and mechanical strength of the crystal is decreased. Movement of the laser beam 102 focus at velocity of 5 cm/s in the horizontal plane parallel to the crystal surface 105 through which laser beam enters the crystal, and perpendicular to the axis 103 of the focused laser beam 102, leads to formation of a set of non-overlapping local regions 206 in the lateral plane 604 which is placed under the crystal surface 105 at the depth defined by focusing depth of the laser beam 102. The average distance between the local regions equals 5 μm. Focus of laser beam 102 is moved in the horizontal plane on a spiral path from periphery deep into the crystal towards the axis of the cylindrical boule 901. Area of the plane 604 with a set of the local regions is increased from periphery deep into the crystal towards the axis of the cylindrical boule 901. On achieving the axis of the cylindrical boule 901 with focus, process of laser treatment is finished. Laser treatment is performed at room temperature T.sub.p=20° C.

(47) Then cylindrical boule 901 is adhered with upper surface 105 on the aluminium plate and heated to temperature of 100-500° C. In this case, because of thermomechanical stress related with difference between the thermal expansion coefficients of aluminium nitride and aluminium, cylindrical boule 901 of aluminium nitride crystal splits along the mechanically reduced plane 604 with separating a nitride aluminium washer 902 lying higher the plane 604 from the main cylindrical aluminium nitride boule.

Example 11

(48) FIG. 13 is the scheme 1300 illustrating the second variation of the method by the example of separating a thin semiconductor washer comprising a grown light diode structure AlGaN/InGaN/AlGaN under the upper surface, from cylindrical semiconductor gallium nitride boule. For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates pulses with energy of 50 μJ, duration of 5 ns and repetition rate of 10000 Hz. Laser beam is focused to the spot of 1 μm in diameter which provides energy density of 5 J/cm.sup.2.

(49) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal and in the light diode structure 407 AlGaN/InGaN/AlGaN, focused under the cylindrical boule surface 105 at the depth of 50 μm, non-overlapping local regions 206 are formed in which structure of chemical bonds is disturbed, chemical interaction between atoms is reduced and mechanical strength of the crystal is decreased. Focus of the laser beam 102 is moved at velocity of 5 cm/s in the horizontal plane on a spiral path from periphery deep into the crystal towards the axis of the cylindrical boule 901. Area of the plane 604 with a set of non-overlapping local regions 206 is increased from periphery deep into the crystal towards the axis of the cylindrical boule 901. The average distance between the local regions equals 5 μm. On achieving the axis of the cylindrical boule 901 with focus, process of laser treatment is finished. Laser treatment is performed at room temperature T.sub.p=20° C.

(50) Then cylindrical boule 901 of gallium nitride crystal is adhered with upper surface 105 on the aluminium plate and heated to temperature of 100-500° C. In this case, because of thermomechanical stress related with difference between the thermal expansion coefficients of gallium nitride and aluminium, cylindrical boule 901 of aluminium nitride crystal splits along the mechanically reduced plane 604 with separating a gallium nitride washer 902 with a grown light diode structure 407 AlGaN/InGaN/AlGaN lying higher the plane 604 from the main cylindrical gallium nitride boule.

Example 12

(51) FIG. 14 is the scheme 1400 illustrating the second variation of the method by the example of separating a thin semiconductor washer comprising a grown light diode structure AlGaN/InGaN/AlGaN in the base, from cylindrical semiconductor gallium nitride boule.

(52) For this purpose Nd:YAG laser is used which operates in the mode of modulated Q-factor at λ=532 nm, and generates pulses with energy of 50 μJ, duration of 5 ns and repetition rate of 10000 Hz. Laser beam is focused to the spot of 1 μm in diameter which provides energy density of 5 J/cm.sup.2.

(53) Under action of the Nd:YAG laser beam 102 with wavelength λ=532 nm weakly absorbed in the gallium nitride crystal, but absorbed in the light diode structure 407 AlGaN/InGaN/AlGaN, focused deeply under the surface 105 of the boule 901, non-overlapping local regions 206 are formed in which structure of chemical bonds is disturbed, chemical interaction between atoms is reduced and mechanical strength of the crystal is decreased. Focus of the laser beam 102 is moved at velocity of 5 cm/s in the horizontal plane on a spiral path from periphery deep into the crystal towards the axis of the cylindrical boule 901. Area of the plane 604 with a set of non-overlapping local regions 206 is increased from periphery deep into the crystal towards the axis of the cylindrical boule 901. The average distance between local regions equals 5 μm. On achieving the axis of the cylindrical boule 901 with focused laser beam 102, process of laser treatment is finished. Laser treatment is performed at room temperature T.sub.p=20° C.

(54) Then cylindrical boule 901 of gallium nitride crystal is adhered with upper surface 105 on the aluminium plate and heated to temperature of 100-500° C. In this case, because of thermomechanical stress related with difference between the thermal expansion coefficients of gallium nitride and aluminium, cylindrical boule 901 of aluminium nitride crystal splits along the mechanically reduced plane 604 with separating a gallium nitride washer 902 with a grown light diode structure 407 AlGaN/InGaN/AlGaN lying lower the plane 604 from the main cylindrical gallium nitride boule.

(55) Despite that this invention has been described and illustrated by examples of the invention embodiments, it should be noted that this invention by no means is not limited by the examples given.