COMPOSITE GATE DIELECTRIC LAYER APPLIED TO GROUP III-V SUBSTRATE AND METHOD FOR MANUFACTURING THE SAME

Abstract

The present invention discloses a composite gate dielectric layer for a Group III-V substrate and a method for manufacturing the same. The composite gate dielectric layer comprises: an Al.sub.xY.sub.2-xO.sub.3 interface passivation layer formed onthe group III-V substrate; and a high dielectric insulating layer formed on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer, wherein 1.2≦x≦1.9.The composite gate dielectric layer modifies the AI/Y ratio of the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer, changes the average number of atomic coordination in the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer, and decreases the interface state density and boundary trap density of the Group III-V substrate, increases the mobility of the MOS channel. By cooperation of the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer and high dielectric insulation layer, it reduces leakage current and improvestolerance of the dielectric layer on the voltage, and improvesthe quality of the MOS capacitor of the Group III-V substrate and enhances its reliability.

Claims

1. A composite gate dielectric layer for a Group III-V substrate, comprising: an Al.sub.xY.sub.2-xO.sub.3 interface passivation layer formed on the group III-V substrate; and a high dielectric insulating layer formed on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer, wherein 1.2≦x≦1.9.

2. The composite gate dielectric layer for a Group III-V substrate according to claim 1, wherein the group III-V substrate includes a GaAs substrate, an InP substrate, a GaSb substrate, an InAs substrate or an InGaAs substrate and an epitaxial wafer thereof, the doping concentration of which is equal to or more than 1×10.sup.15 cm.sup.−3 and equal to or less than 5×10.sup.17 cm.sup.−3.

3. The composite gate dielectric layer for a Group III-V substrate according to claim 1, wherein the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer has a thickness of 0.4 nm or more and 4 nm or less.

4. The composite gate dielectric layer for a Group III-V substrate according to claim 1, wherein the high dielectric insulating layer includes HfO.sub.2, ZrO.sub.2, La.sub.2O.sub.3 or Y.sub.2O.sub.3, and a ternary or plural compound obtained by mixing the above mentioned four materials, wherein the high dielectric insulating layer has a thickness of 0 nm or more and less than or equal to 4 nm.

5. A method for manufacturing a composite gate dielectric layer for a group III-V substrate, comprising the following steps of: Step 1: cleaning the group III-V substrate, growing an Al.sub.2O.sub.m passivation layer on the group III-V substrate, wherein 2.5≦m≦3; Step 2: growing a Y.sub.2O. strengthening layer on the Al.sub.2O.sub.m passivation layer, wherein 2.5≦n≦3; Step 3: thermally treating the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer in situ to mix the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer to obtain an interface passivation layer of Al.sub.xY.sub.2-xO.sub.3, wherein 1.2≦x≦1.9; and Step 4: growing a high dielectric insulating layer on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer.

6. The method according to claim 5, wherein the step 1 of growing the Al.sub.2O.sub.m passivation layer on the group III-V substrate comprises growing an Al.sub.2O.sub.m passivation layer with a thickness of d.sub.1on the group III-V substrate by atomic layer deposition at a temperature of 200° C. to 400° C., wherein 0.2 nm≦d.sub.1≦3.8 nm.

7. The method according to claim 6, wherein the method regulates an oxygen content in the Al.sub.2O.sub.m passivation layer by adjusting the temperature of atomic layer deposition ranging from 200° C. to 400° C., wherein at 200° C., it tends to form a Al.sub.2O.sub.m passivation layer with a low oxygen content, m=2.5; at 400° C., it tends to form a Al.sub.2O.sub.m passivation layer with a high oxygen content, m=3, wherein the lower oxygen content in the Al.sub.2O.sub.m passivation layer improves a flexibility of the Al—O tetrahedron mesh structure in the Al.sub.2O.sub.m passivation layer, and enhances a characteristic of rotation of the Al—O tetrahedron in the Al.sub.2O.sub.m passivation layer, so as to passivize the defects on the surface of the group III-V substrate, and the higher oxygen content in the Al.sub.2O.sub.m passivation layer decreases the leakage current of the composite gate dielectric layer and improve the reliability.

8. The method according to claim 6, wherein the step 2 of growing the Y.sub.2O.sub.n strengthening layer on the Al.sub.2O.sub.m passivation layer comprises growing the Y.sub.2O.sub.n strengthening layer with a thickness of d.sub.2on the Al.sub.2O.sub.m passivation layer by atomic layer deposition at a temperature of 200° C. to 400° C., wherein 0.4 nm≦d.sub.1+d.sub.2≦4 nm.

9. The method according to claim 8, wherein the method regulates an oxygen content in the Y.sub.2O.sub.n strengthening layer by adjusting the d temperature of the atomic layer deposition ranging from 200° C. to 400° C., wherein at 200° C., it tends to form a Y.sub.2O.sub.n strengthening layer with a low oxygen content, n=2.5; at 400° C., it tends to form a Y.sub.2O.sub.n strengthening layer with a high oxygen content, n=3.

10. The method according to claim 5, wherein the step 3 of thermally treating the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer in situ is implemented by thermally treating the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer in an atomic layer deposition apparatus at a temperature ranging from 200° C. to 400° C.

11. The method according to claim 10, wherein the Al.sub.0O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer are mixed according to a certain mixing ratio by adjusting the temperature for the thermal treating in situ, and the mixing ratio is determined by a ratio of d1:d2 of the thickness d.sub.1of the Al.sub.2O.sub.m passivation layer and the thickness d.sub.2 of the Y.sub.2O.sub.n strengthening layer, wherein 19:1≦d.sub.1:d.sub.2≦1:19; the Al.sub.xY.sub.2-xO.sub.3interface passivation layer is obtained by mixing the Al.sub.2O.sub.m passivation layer and Y.sub.2O.sub.n strengthening layer to implement an average coordination number of the Al.sub.xY.sub.2-xO.sub.3interface passivation layer ranging from 2.8 to 4.2, and in turn to meet the requirement of interfacial defect density and reliability of various devices; wherein the average coordination number of 2.8 is obtained under a condition in which d.sub.1:d.sub.2=19:1, m=3 and n=3; and the average coordination number of is 4.2 is obtained under a condition in which d1:d2=1:19, m=2.5 and n=2.5.

12. The method according to claim 11, wherein the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer, 1.2≦x≦1.9 is a referable result of the interface passivation layer, and the average coordination number of the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer ranges from 3.28 to 2.86, in which the average coordination number is 3.28 at x=1.2 and 2.86 at x=1.9.

13. The method according to claim 5, wherein the step 4 of growing the high dielectric insulating layer on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer is implemented by utilizing atomic layer deposition to deposit a high dielectric insulating layer with a thickness of equal to or more than 0 nm and less than or equal to 4 nm on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer at a temperature ranging from of 200° C. to 400° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to further illustrate the present invention, the present invention will be described in detail with reference to the accompanying drawings, in which:

[0028] FIG. 1 is a schematic structural view of a composite gate dielectric layer for a group III-V substrate provided by the present invention;

[0029] FIG. 2 is a process flowchart for manufacturing the composite gate dielectric layer as shown in FIG. 1 provided by the present invention;

[0030] FIG. 3 is a flowchart of a method for manufacturing the composite gate dielectric layer as shown in FIG. 1 provided by the present invention.

DETAILED DESCRIPTION

[0031] In order to make the object, technical solution and advantages of the present invention to be more apparent, the invention will be described in conjunction with particular embodiments and with reference to the accompanying drawings.

[0032] As shown in FIG. 1, FIG. 1 is a schematic structural view of a composite gate dielectric layer for a group III-V substrate provided by the present invention.The composite gate dielectric layer comprises: an Al.sub.xY.sub.2-xO.sub.3 interface passivation layer formed onthe group III-V substrate; and a high dielectric insulating layer formed on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer, wherein 1.2≦x≦1.9. The Al.sub.xY.sub.2-xO.sub.3 interface passivation layer 23 and the HfO.sub.2 high dielectric insulating layer 24 constitute a composite gate dielectric layer 2.

[0033] In FIG. 1, the group III-V substrate 1 includes a GaAs substrate, an InP substrate, a GaSb substrate, an InAs substrate or an InGaAs substrate and an epitaxial wafer thereof, the doping concentration of which is equal to or more than 1×10.sup.15 cm.sup.−3 and equal to or less than 5×10.sup.17 cm.sup.−3. The Al.sub.xY.sub.2-xO.sub.3 interface passivation layer 23 has a thickness of 0.4 nm or more and 4 nm or less.The high dielectric insulating layer 24 includes HfO.sub.2, ZrO.sub.2, La.sub.2O.sub.3 or Y.sub.2O.sub.3, and a ternary or plural compound obtained by mixing the above mentioned four materials, wherein the high dielectric insulating layer 24 has a thickness of 0 nm or more and less than or equal to 4 nm.

[0034] FIG. 2 is a process flowchart for manufacturing the composite gate dielectric layer as shown in FIG. 1 provided by the present invention. As can be seen from FIG. 2, the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer 23 formed on the group III-V substrate 1 is obtainedby an in situ thermal treatment, i.e. an in situ anneal treatment to mutually diffuse the Al.sub.2O.sub.m passivation layer 21 and the Y.sub.2O.sub.n strengthening layer 22.

[0035] The gate dielectric layer composed of the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer 23 and the HfO.sub.2 high dielectric insulating layer 24 is a composite gate dielectric layer, which may reduce the interface state density and the boundary trap density, increase the MOS channel mobility, reduces the leakage current of the gate, and further improve the tolerance of the dielectric layer on the voltage and improve the quality and reliability of MOS device.

[0036] FIG. 3 is a flowchart of a method for manufacturing the composite gate dielectric layer as shown in FIG. 1 provided by the present invention.The method comprises the following steps.

[0037] At step 1: cleaning the group III-V substrate, growing an Al.sub.2O.sub.m passivation layer on the group III-V substrate, wherein 2.5≦m≦3.

[0038] In such a step,the step of growing the Al.sub.2O.sub.m passivation layer on the group III-V substrate comprises growing an Al.sub.2O.sub.m passivation layer with a thickness of d.sub.1on the group III-V substrate by atomic layer deposition at a temperature of 200° C. to 400° C., wherein 0.2 nm≦5 d.sub.1≦3.8 nm. the method regulates an oxygen content in the Al.sub.2O.sub.m passivation layer by adjusting the temperature of atomic layer deposition ranging from 200° C. to 400° C., wherein at 200° C., it tends to form a Al.sub.2O.sub.m passivation layer with a low oxygen content, m=2.5; at 400° C., it tends to form a Al.sub.2O.sub.m passivation layer with a high oxygen content, m=3. The lower oxygen content in the Al.sub.2O.sub.m passivation layer may improve a flexibility of the Al—O tetrahedron mesh structure in the Al.sub.2O.sub.m passivation layer, and enhance a characteristic of rotation of the Al—O tetrahedron in the Al.sub.2O.sub.m passivation layer, so as to passivize the defects on the surface of the group III-V substrate. The higher oxygen content in the Al.sub.2O.sub.m passivation layer may decrease the leakage current of the composite gate dielectric layer and improve the reliability.

[0039] Step 2: growing aY.sub.2O.sub.n strengthening layer on the Al.sub.2O.sub.m passivation layer, wherein 2.5≦n≦3.

[0040] In such a step, the step of growing the Y.sub.2O.sub.n strengthening layer on the Al.sub.2O.sub.m passivation layer comprises growing the Y.sub.2O.sub.n strengthening layer with a thickness of d.sub.2 on the Al.sub.2O.sub.m passivation layer by atomic layer deposition at a temperature of 200° C. to 400° C., wherein 0.4 nm≦d.sub.1+d.sub.2≦4 nm. The method regulates an oxygen content in the Y.sub.2O.sub.n strengthening layer by adjusting the d temperature of the atomic layer deposition ranging from 200° C. to 400° C., wherein at 200° C., it tends to form a Y.sub.2O.sub.n strengthening layer with a low oxygen content, n=2.5; at 400° C., it tends to form a Y.sub.2O.sub.n strengthening layer with a high oxygen content, n=3.

[0041] Step 3: thermally treating the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer in situ to mix the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer to obtain an interface passivation layer of Al.sub.xY.sub.2-xO.sub.3 , wherein 1.2≦1.9.

[0042] In such a step, the step of thermally treating the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer in situ is implemented by thermally treating the Al.sub.2O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer in an atomic layer deposition apparatus at a temperature ranging from 200° C. to 400° C. In the above mentioned technical solution, the Al.sub.0O.sub.m passivation layer and the Y.sub.2O.sub.n strengthening layer are mixed according to a certain mixing ratio by adjusting the temperature forthe thermal treating in situ, and the mixing ratio is determined by a ratio of d.sub.1:d.sub.2 of the thickness d.sub.1 of the Al.sub.2O.sub.m passivation layer and the thickness d.sub.2 of the Y.sub.2O.sub.n strengthening layer, wherein 19:1≦d.sub.1:d.sub.2≦1:19. In such a method, the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer is obtained by mixing the Al.sub.2O.sub.m passivation layer and Y.sub.2O.sub.n strengthening layer to implement an average coordination number of the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer ranging from 2.8 to 4.2, and in turn to meet the requirement of interfacial defect density and reliability of various devices. The average coordination number of 2.8 is obtained under a condition in which d.sub.1:d2=19:1, m=3 and n=3; and the average coordination number of is 4.2 is obtained under a condition in which d.sub.1:d.sub.2=1:19, m=2.5 and n=2.5. In the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer, 1.2≦x≦1.9 is a referable result of the interface passivation layer, and the average coordination number of the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer ranges from 3.28 to 2.86, in which the average coordination number is 3.28 at x=1.2 and 2.86 at x=1.9.

[0043] Step 4: growing a high dielectric insulating layer on the AI.sub.xY.sub.2-xO.sub.3 interface passivation layer.

[0044] In such a step, the step of growing the high dielectric insulating layer on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer is implemented by utilizingatomic layer deposition to deposit a high dielectric insulating layer with a thickness of equal to or more than 0 nm and less than or equal to 4 nm on the Al.sub.xY.sub.2-xO.sub.3 interface passivation layer at a temperature ranging from of 200° C. to 400° C.

Embodiment 1

[0045] A method of manufacturing a composite gate dielectric layer for a group III-V substrate in accordance with the embodiment 1 of the present invention comprises the following steps.

[0046] In a step 101, an InP substrate with a thickness of 400 μm and an N-type doping concentration of 5×10.sup.15 cm.sup.−3is cleaned, and then Al.sub.2O.sub.2.5 layer with a thickness of 0.5 nm is grown by atomic layer deposition at 200° C. The step 101 particularly comprises the following sub steps.

[0047] In a step101.1: the InP substrate is immerged completely in absolute ethanol in which the surface of the InP substrate directs upwards, and is washed with ultrasonic wave for 3 minutes to remove partially polarized organic material on the surface;

[0048] In a step 101.2: the InP substrate after being processed in the step 101.1 is immersed in a deionized water for 15 seconds and then taken out;

[0049] In a step 101.3: the InP substrate after being processed in the step 101.2 is completely immersed in acetone in which the surface of the InP substrate directs upwards, and is cleaned by ultrasonic wave for 3 minutes to remove the unpolarized organic substance on the surface;

[0050] In a step101.4: the InP substrate after being processed in the step 101.3 is immersed in the deionized water for 15 seconds and then taken out;

[0051] In a step 101.5: a concentrated hydrochloric acid (mass fraction ratio of 37%) and a deionized water are mixed in a volume ratio of 1:9; the InP substrate after being processed in the step 101.4 in which the surface of the InP substrate directs upwards is completely immersed into the dilute hydrochloric acid solution and maintained forone minute;

[0052] In a step 101.6: the InP substrate after being processed in the step 101.5 is immersed in the deionized water for 15 seconds and taken out;

[0053] In a step 101.7: the lnP substrate after being processed in thestep 101.6 in which the surface of the InP substrate directs upwards is completely immersed in a solution of ammonia sulfide (NH.sub.4).sub.2Swith a mass fraction of 22% for 15 minutes;

[0054] In a step 101.8: the InP substrate after being processed in thestep 101.7 is immersed in deionized water for 15 seconds and then taken out and quickly dried with nitrogen gas.

[0055] In a step 101.9: the InP substrate after being processed in thestepstep 101.8 is placed in the atomic layer deposition apparatus, and trimethylaluminum and water are used as a reaction precursor (in an order of introducing trimethylaluminum firstly and then water)to grow an Al.sub.2O.sub.5 layer with a thickness of 0.5 nm at 200° C. by atomic layer deposition.

[0056] In a step 102: a Yttrium tris(butylcyclopentadienide) and water were used as reaction precursors (in an order of introducing water firstly and then yttrium tris (butylcyclopentadienyl)) to grow a Y.sub.2O.sub.3 layer with a thickness of 0.3 nm by atomic layer deposition .

[0057] In a step 103: the grown Al.sub.2O.sub.5 layer and the Y.sub.2O.sub.3 layer are subjected to an in-situ thermal treatment in an atomic layer deposition apparatus at 300° C. to obtain an Al.sub.1.25Y.sub.0.75O.sub.3 interface passivation layer with a thickness of 0.8 nm. The step 103 particularly comprises the following sub steps.

[0058] Step 103.1: After the step 102 is completed, a nitrogen gas with a purity of 99.999% is introduced into the atomic layer deposition chamber, and the pressure is maintained at 50 Pascals until the gas pressure became stable.

[0059] Step 103.2: an in-situ annealing treatment is carried out at a temperature of 300° C. for 30 minutes to diffuse Al and Y atoms to form an Al.sub.1.25Y.sub.0.75O.sub.3 interface passivation layer with an average coordination number of 3.25 and a thickness of 0.8 nm.

[0060] Step 104: an atomic layer deposition method is used to growa HfO.sub.2 layer with a thickness of 3 nm at 300° C. on the annealed Al.sub.1.25Y.sub.0.75O.sub.3 interface passivation layer by using bi-(ethylcyclopentadienyl) hafnium dichloride and water as the reaction precursor (in an order of introducing bi-(ethylcyclopentadienyl) hafnium dichloride firstly and then water).

Example 2

[0061] A method of manufacturing a composite gate dielectric layer for a group III-V substrate in accordance with the embodiment 2 of the present invention comprises the following steps.

[0062] In a step 201: an In.sub.0.53Ga.sub.0.47As substrate with an epitaxial layer thickness of 20 nm and an N-type doping concentration of 1×10.sup.18cm.sup.−3 on a silicon-based insulator is cleaned. The silicon substrate is intrinsic silicon and a thickness of the insulating layer is 50 nm.Then an Al.sub.2O.sub.2.5 layer with a thickness of 0.3 nm is grown at 200° C. by atomic layer deposition. The step 201 particularly comprises the following sub steps.

[0063] In a step 201.1: the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulator is completely submerged in anhydrous ethanol and cleaned by ultrasonic for 3 minutes to remove the partially polarized organic material on the surface;

[0064] In a step 201.2: the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulator after being processed in the step 201.1 is immersed in the deionized water for 15 seconds and then taken out;

[0065] In a step 201.3: the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulatorafter being processed in the step 201.2 is completely immersed into acetone in which its surface direct upwards, and is cleaned by ultrasonic wave for 3 minutes to remove the unpolarized organic substance on the surface;

[0066] In a step 201.4: theIn.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulator after being processed in the step 201.3 is immersed in the deionized water for 15 seconds and then taken out;

[0067] In a step 201.5: a concentrated hydrochloric acid (mass fraction of 37%) and deionized water are mixed in a volume ratio of 1:4; the surface of the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulator after being processed in the step 201.4 is completely immersed into the mixed dilute hydrochloric acid solution for 1 minute;

[0068] In a step 201.6: the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulator after being processed in the step 201.5 is immersed in the deionized water for 15 seconds and then taken out;

[0069] In a step 201.7: the surface of the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulatorafter being processed in the step 201.6 is immerged in a solution of ammonium sulfide (NH.sub.4).sub.2S with a mass ratio of 22% in for 15 minutes;

[0070] In a step 201.8: the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulator after being processed in the step 201.7 is immersed in the deionized water for 15 seconds, then taken out and rapidly dried with nitrogen.

[0071] In a step 201.9: the In.sub.0.53Ga.sub.0.47As substrate on the silicon-based insulator after being processed in the step 201.8 is placed in an atomic layer deposition apparatus, and trimethylaluminum and water are used as reaction precursors (in an order of introducing trimethylaluminum firstly and then water)to grow an Al.sub.2O.sub.2.5 layer with a thickness of 0.3 nm at 200° C. by using atomic layer deposition.

[0072] In a step 202: yttrium tris (butylcyclopentadienide) and water are used as reaction precursors (in an order of introducing yttrium tris (butylcyclopentadienyl)firstly and then water) at 300° C. to grow a Y.sub.2O.sub.3 layer with a thickness of 0.3 nm by using atomic layer deposition.

[0073] In a step 203: the grown Al.sub.2O.sub.5 layer and the Y.sub.2O.sub.3 layer are thermally treated in-situ in an atomic layer deposition apparatus at 300° C. to obtain an AlYO.sub.3 interface passivation layer having a thickness of 0.6 nm. The step 203 particularly comprised the following sub steps.

[0074] In a step 203.1: after the step 202 is completed, a nitrogen gas having a purity of 99.999% is introduced into the atomic layer deposition chamber, and the pressure is maintained at 50 Pascals until the gas pressure became stable.

[0075] In a step 203.2: an in-situ annealing treatment is carried out at a temperature of 300° C. for 30 minutes to diffuse Al and Y atoms to form an AlYO.sub.3 interface passivation layer with an average coordination number of 3.4 nm and a thickness of 0.6 nm.

[0076] In a step 204: a layer of Hf.sub.0.9Y.sub.0.13O.sub.2 with a thickness of 3 nm is grown on the AlYO.sub.3 interface passivation layer after it is annealed at 300° C. by using atomic layer deposition. The step 204 particularly comprises the following sub steps.

[0077] In a step 204.1: after the step 203.2, bi-(ethylcyclopentadienyl) hafnium dichloride and water are used as reaction precursors at 300° C. (in an order of introducing bi-(ethylcyclopentadienyl) hafnium dichloride firstly and then water) to grow a HfO.sub.2 layer with a thickness of 1.35 nm by atomic layer deposition;

[0078] In a step 204.2: after the step 204.1, yttrium tris (butylcyclopentadiene) and water are used as the reaction precursor at 300° C. (in an order of introducing yttrium tris (butylcyclopentadienyl) firstly and then water) to grow a Y.sub.2O.sub.3 layer with a thickness of 0.3 nm at 300° C. by atomic layer deposition.

[0079] In a step 204.3: after the step 204.2, bi-(ethylcyclopentadienyl) hafnium dichloride and water are used as the reaction precursors at 300° C. (in an order of introducing bi-(ethylcyclopentadienyl) hafnium dichloride firstly and then water) to grow a HfO.sub.2 layer with a thickness of 1.35 nm.

[0080] In a step 204.4: After the step 204.3, a nitrogen gas with a purity of 99.999% is introduced into the atomic layer deposition chamber, and the pressure is maintained at 50 Pascals until the gas pressure became stable.

[0081] In a step 204.5: an in-situ annealing iscarried out at a temperature of 300° C. for 30 minutes to diffuse the Hf and Y atoms to form a high dielectric insulating layer of Hf.sub.0.9Y.sub.0.13O.sub.2with a thickness of 3 nm.

Example 3

[0082] A method of manufacturing a composite gate dielectric layer for a group III-V substrate in accordance with the embodiment 3 of the present invention comprises the following steps.

[0083] In a step301: a GaAs substrate with a thickness of 400 m and an N-type doping concentration of 1×10.sup.17cm.sup.−3iscleaned, and then a Al.sub.2O.sub.2.7 layer is grown at 250° C. to have a thickness of 2 nm by an atomic layer deposition. The step301 particularly comprises the following sub steps.es:

[0084] In a step301.1: the GaAs substrate in which its surface directs upward is completely immersed in absolute ethanol and cleaned by ultrasonic wave for 3 minutes to remove the partially polarized organic substance on the surface;

[0085] In a step301.2: the GaAs substrate after being processed in the step 301.1 is immersed in the deionized water for 15 seconds and then taken out;

[0086] In a step301.3: the surface of the GaAs substrate after being processed in the step 301.2 is completely immersed in acetone and cleaned by ultrasonic wave for 3 minutes to remove the unpolarized organic substance on the surface;

[0087] In a step301.4: the GaAs substrate after being processed in the step 301.3 is immersed in the deionized water for 15 seconds and then taken out;

[0088] In a step301.5: a concentrated hydrochloric acid (with a mass fraction of 37%) and deionized water are mixed in a volume ratio of 1:4; the InP substrate in which its surface directs upwards after being processed in the step 101.4 is completely immersed into the diluted hydrochloric acid solution to maintain 1 minute;

[0089] In a step301.6: the GaAs substrate after being processed in the step 301.5 is immersed in the deionized water for 15 seconds and then taken out;

[0090] In a step301.7: the GaAs substrate in which its surface direct upwardsafter being processed in the step 301.6 is immerged in a solution of ammonium sulfide (NH.sub.4).sub.2S with a mass ratio of 22% for 15 minutes;

[0091] In a step301.8: the GaAs substrate after being processed in the step 301.7 is immersed in the deionized water for 15 seconds, then taken out and rapidly dried with nitrogen gas;

[0092] In a step301.9: the GaAs substrate after being processed in the step 301.8 is placed in the atomic layer deposition apparatus and trimethylaluminum and water are used as the reaction precursors (in an order of introducing thetrimethylaluminum firstly and then water) to grow a Al.sub.2O.sub.2.7 layer with a thickness of 2 nm at 250° C. by atomic layer deposition.

[0093] In a step302: Yttrium tris(butylcyclopentadienide) and water are used as reaction precursors (in an order of introducing yttrium tris(butylcyclopentadienyl)firstly and then water) to grow a Y.sub.2O.sub.3 layer with a thickness of 0.3 nm at 300° C. by atomic layer deposition.

[0094] In a step303: the grown Al.sub.2O.sub.2.7 layer and the Y.sub.2O.sub.3 layer are thermally treated in situ in the atomic layer deposition equipment at a temperature of 300° C. to obtain the Al.sub.1.74Y.sub.0.26O.sub.3 interface passivation layer with a thickness of 2.3 nm.

[0095] In a step303.1: After the step 302 is completed, a nitrogen gas with a purity of 99.999% is introduced into the atomic layer deposition chamber, and the pressure is maintained at 50 Pascals until the gas pressure became stable.

[0096] In a step303.2: an In-situ annealing treatment is carried out at a temperature of 300° C. for 30 minutes to diffuse Al and Y atoms to form an Al.sub.1.74Y.sub.0.26O.sub.3 interfacial passivation layer with an average coordination number of 2.96 and a thickness of 2.3 nm.

[0097] In a step 304, treated with bis(ethylcyclopentadienyl) hafnium dichloride and water are used as the reaction precursors (in an order of introducing bis(ethylcyclopentadienyl) hafnium dichloride firstly and water) to grown a HfO.sub.2 layer with a thickness of 2 nm at 300° C. on the annealed Al.sub.1.74Y.sub.0.26O.sub.3 interfacial passivation layer by atomic layer deposition

[0098] While the invention has been described in detail with reference to specific embodiments thereof, it is to be understood that the above is intended only as illustrative and not restrictive, and that the invention is not limited to the particular embodiments, Any modifications, equivalent substitutions, improvements and the like within the spirit and principles of the present invention are intended to be included within the scope of the present invention.