Nondestructive testing method for oxide semiconductor layer and method for making oxide semiconductor layer

1. A nondestructive testing method for an oxide semiconductor layer, comprising:

applying excitation light to an amorphous or polycrystalline target oxide semiconductor layer to be tested and measuring an intensity of photoluminescence in a wavelength region longer than a wavelength corresponding to a bandgap energy among light emitted from the target oxide semiconductor layer; and

estimating a film property of the target oxide semiconductor layer on the basis of measurement results.

2. The nondestructive testing method according to claim 1 , further comprising:

measuring a photoluminescence intensity of an amorphous or polycrystalline reference oxide semiconductor layer in the same manner as that of the target oxide semiconductor layer and measuring a film property of the reference oxide semiconductor layer so as to obtain a relationship between the photoluminescence intensity and the film property, the reference oxide semiconductor layer having the same element composition as and being prepared by the same process and at the same deposition temperature as the target oxide semiconductor layer,

wherein the film property of the target oxide semiconductor layer is estimated on the basis of this relationship.

3. The nondestructive testing method according to claim 2 , wherein the film property of the reference oxide semiconductor layer measured is a carrier density and a carrier density of the target oxide semiconductor layer is estimated on the basis of a relationship between the photoluminescence intensity and the carrier density of the reference oxide semiconductor layer.

4. The nondestructive testing method according to claim 3 , wherein the carrier density of the reference oxide semiconductor layer is measured by using a Hall effect.

5. The nondestructive testing method according to claim 1 , wherein an oxide semiconductor layer serving as an active layer incorporated in a semiconductor element can be used as the target oxide semiconductor layer and tested noncontactingly.

6. A method for making an oxide semiconductor layer, comprising:

depositing an amorphous or polycrystalline oxide semiconductor layer on a substrate; and

testing a film property of the amorphous or polycrystalline oxide semiconductor layer by a nondestructive testing method for an oxide semiconductor layer, comprising:

applying excitation light to an amorphous or polycrystalline target oxide semiconductor layer to be tested and measuring an intensity of photoluminescence in a wavelength region longer than a wavelength corresponding to a bandgap energy among light emitted from the target oxide semiconductor layer; and

estimating a film property of the target oxide semiconductor layer on the basis of measurement results.

7. The method according to claim 6 , wherein the film property of the amorphous or polycrystalline oxide semiconductor layer during deposition is monitored in situ by the nondestructive testing method and a deposition condition is controlled on the basis of monitored results so that a desired film property is obtained.

8. The method according to claim 7 , wherein at least one deposition condition selected from an oxygen partial pressure in a deposition atmosphere, a substrate temperature, and a deposition rate is controlled.

9. The method according to claim 6 , further comprising a step of:

annealing the amorphous or polycrystalline oxide semiconductor layer,

wherein the film property of the amorphous or polycrystalline oxide semiconductor layer is tested by the nondestructive testing method after deposition,

the annealing is performed after the testing, and

an annealing condition is set on the basis of results of the nondestructive testing so that a desired film property is obtained.

10. The method according to claim 6 , further comprising:

annealing the amorphous or polycrystalline oxide semiconductor layer after deposition,

wherein the film property of the amorphous or polycrystalline oxide semiconductor layer during annealing is monitored in situ by the nondestructive testing method and an annealing condition is controlled on the basis of monitored results so that a desired film property is obtained.

11. The method according to claim 9 , wherein at least one annealing condition selected from an oxygen partial pressure in an annealing atmosphere, an annealing temperature, and an annealing time is controlled.

12. The method according to claim 6 , wherein the method is a part of a process for producing a semiconductor element that includes the amorphous or polycrystalline oxide semiconductor layer serving as an active layer,

the method further comprises a step of testing the film property of the amorphous or polycrystalline oxide semiconductor layer by the nondestructive testing method after the amorphous or polycrystalline oxide semiconductor layer is made, and

a step to be taken next is selected on the basis of results of the nondestructive testing.

13. The method according to claim 12 , wherein

the semiconductor element is a field effect transistor.