Blank mask and photomask using the same
A blank mask including a transparent substrate, a phase shift film disposed on the transparent substrate, and a light shielding film disposed on the phase shift film. The phase shift film has XRD maximum peak at 2θ of 15° to 30° when normal mode XRD analysis is performed on an upper surface of the phase shift film. The transparent substrate has XRD maximum peak at 2θ of 15° to 30° when performing normal mode XRD analysis on a lower surface of the transparent substrate. AI1 value of the blank mask expressed by below Equation is 0.9 to 1.1. AI 1 = XM 1 XQ 1 XM1 is the maximum value of the measured X-ray intensity when the normal mode XRD analysis is performed on upper surface of the phase shift film. XQ1 is the maximum value of the measured X-ray intensity when the normal mode XRD analysis is performed on the lower surface of the transparent substrate.
1 . A method of forming a blank mask, comprising:
preparing a transparent substrate; and
forming a phase shift film on the transparent substrate;
wherein the phase shift film comprises a phase difference adjustment layer and a protective layer on the phase difference adjustment layer,
wherein forming the phase shift film on the transparent substrate comprises:
forming a phase difference adjustment layer on the transparent substrate by sputtering using a magnet disposed on a backside of a sputtering target and rotated during sputtering to generate a magnetic field of 30 mT to 50 mT at the surface of the sputtering target; and
forming a protective layer on the phase difference adjustment layer;
wherein the sputtering is performed in an argon-nitrogen-helium atmosphere,
wherein the sputtering is slopped when then Del 1 value measured by elipsometry is apprximately zero at a photon energy of 3.8 eV to 4.64 eV, with PE 1 =3.0 eV and PE 2 =5.0 eV,
wherein the phase shift film has a XRD maximum peak at 2θ of 15° to 30° when a normal mode X-Ray Diffraction (XRD) analysis is performed on an upper surface of the phase shift film,
where the transparent substrate has a XRD maximum peak at 2θ of 15° to 30° when a normal mode XRD analysis is performed on a lower surface of the transparent substrate, and
wherein the blank mask has AI1 value of 0.9 to 1.1 expressed by:
A
I
1
=
XM
1
XQ
1
[
Equation
1
]
where
XM1 is a maximum value of a measured X-ray intensity when the normal mode XRD analysis is performed on the upper surface of the phase shift film, and
XQ1 is a maximum value of the measured X-ray intensity when the normal mode XRD analysis is performed on the lower surface of the transparent substrate,
wherein the blank mask has the photon energy of the incident light at the point where Del_1 expressed by Equation 7 below is 0 is 3.8 to 4.64 eV, when the PE1 value is 3.0 eV and the PE2 value is 5.0 eV;
Del_
1
=
lim
Δ
PE
→
0
(
Δ
DPS
Δ
PE
)
[
Equation
7
]
where in the Equation 7,
the DPS value is, after removing the light shielding film from the blank mask, the phase difference between the P wave and the S wave of reflected light if the phase difference between the P wave and S wave of the reflected light is 180° or less, or a value obtained by subtracting the phase difference between the P wave and the S wave of the reflected light from 360° if the phase difference between the P wave and the S wave of the reflected light is more than 180° when the surface of the phase shift film is measured with a spectroscopic ellipsometer by applying an incident angle of 64.5°, and
the PE value is the photon energy of the incident light within the range of PE1 to PE2,
wherein the phase shift film comprises a phase difference adjustment layer and a protective layer disposed on the phase difference adjustment layer, and
wherein the phase shift film comprises a transition metal, silicon, oxygen and nitrogen.
2 . The method claim 1 ,
wherein forming the phase shift film on the transparent substrate further comprises irradiating a light with a wavelength of 200 nm or less to a surface of the phase difference adjustment layer by using light source having a power of 2 to 10 mW/cm 2 after forming a phase difference adjustment layer on the transparent substrate by sputtering.
3 . The method claim 2 ,
wherein irradiating a light with a wavelength of 200 nm or less to a surface of the phase difference adjustment layer is performed for 5 to 20 minutes.
4 . The method claim 1 ,
wherein an intensity of sputtering electric power is 1.8 to 2.2 kW in forming a phase difference adjustment layer on the transparent substrate by sputtering.
5 . The method claim 1 ,
wherein forming a protective layer on the phase difference adjustment layer comprises heating the phase difference adjustment layer at 150° C. to 500° C.
6 . The method claim 1 ,
wherein the phase shift film has a first peak, which is the XRD maximum peak at 2θ of 15° to 25° when the fixed mode XRD analysis is performed on the upper surface of the phase shift film,
wherein the transparent substrate has a second peak, which is the XRD maximum peak at 2θ of 15° to 25° when the fixed mode XRD analysis is performed on the lower surface of the transparent substrate, and
wherein AI2 value expressed by Equation 2 below is 0.9 to 1.1;
A
I
2
=
XM
2
XQ
2
[
Equation
2
]
wherein the Equation 2,
the XM2 is the intensity value of the first peak, and
the XQ2 is the intensity value of the second peak.
7 . The method of claim 1 ,
wherein AI3 value expressed by Equation 3 below is 0.9 to 1.1;
A
I
3
=
AM
1
AQ
1
[
Equation
3
]
wherein the Equation 3,
the AM1 is an area of the region where 2θ is 15° to 30° in the X-ray intensity graph measured when normal mode XRD analysis is performed on the upper surface of the phase shift film, and
the AQ 1 is an area of the region where 2θ is 15° to 30° in an X-ray intensity graph measured when normal mode XRD analysis is performed on the lower surface of the transparent substrate.
8 . The method of claim 1 ,
wherein AI4 value expressed by Equation 4 below is 0.9 to 1.1;
A
I
4
=
XM
4
XQ
4
[
Equation
4
]
wherein the Equation 4,
the XM4 is the X-ray intensity where 2θ is 43° when the normal mode XRD analysis performed on the upper surface of the phase shift film, and
the XQ4 is the X-ray intensity where 2θ is 43° when the normal mode XRD analysis performed on the lower surface of the transparent substrate.
9 . The method of claim 1 ,
wherein a photon energy of incident light at the point where the Del_1 value according to Equation 7 below is 0 is 1.8 to 2.14 eV when PE1 is 1.5 eV and PE2 is 3 eV;
Del_
1
=
lim
Δ
PE
→
0
(
Δ
DPS
Δ
PE
)
[
Equation
7
]
wherein the Equation 7, the DPS value is a phase difference between the P wave and the S wave of reflected light if the phase difference between the P wave and the S wave of the reflected light is 180° or less or a value obtained by subtracting the phase difference between the P wave and the S wave of the reflected light from 360° if the phase difference between the P wave and the S wave of the reflected light is more than 180°, when the phase shift film is measured with a spectroscopic ellipsometer by applying an incident angle of 64.5°, and
the PE value is the photon energy of the incident light within the range of the PE1 value to the PE2 value.
10 . The method of claim 1 ,
wherein the photon energy of the incident light at the point where the Del_1 value is 0 is 1.8 to 2.14 eV, when the PE1 value is 1.5 eV and the PE2 value is 3.0 eV.
11 . The method of claim 1 ,
wherein the average value of the Del_1 is 78 to 98°/eV, when the PE1 value is 1.5 eV and the PE2 value is the minimum value within photon energy values of incident light at the point where the Del_1 value is 0.
12 . The method of claim 1 ,
wherein the average value of the Del_1 is −65 to −55/eV, when the PE1 value is the minimum value within photon energy values of the incident light at the point where the Del_1 value is 0, and the PE2 value is the maximum value within the photon energy values of the incident light at the point where the Del_1 value is 0.
13 . The method of claim 1 ,
wherein the average value of the Del_1 is 60 to 120°/eV, when the PE1 value is the maximum value within photon energy values of incident light at a point where the Del_1 value is 0, and when the PE2 value is 5.0 eV.
14 . The method of claim 1 ,
wherein the maximum value of the Del_1 value is 105 to 300/eV, when the PE1 value is 1.5 eV and the PE2 value is 5.0 eV.
15 . The method of claim 1 ,
wherein the photon energy of the incident light at the point where the maximum value of the Del_1 value is 4.5 eV or more.
16 . The method of claim 1 ,
wherein the phase difference adjustment layer comprises nitrogen in an amount of 40 to 60 atom %,
wherein the protective layer comprises nitrogen in an amount of 20 to 40 atom %, and
wherein the protective layer comprises a region in which the ratio of nitrogen content to oxygen content in the thickness direction is 0.4 to 2, and the region has a thickness of 30 to 80% compared to a total thickness of the protective layer.