SURFACE COMPOSITE FILM STRUCTURE WITH LONGITUDINAL TRANSMISSION CUTOFF AND TRANSVERSE TRANSMISSION CONDUCTION, AND PREPARATION METHOD AND APPLICATION THEREOF

Abstract

A surface composite film structure with longitudinal transmission cutoff and transverse transmission conduction, and a preparation method and application thereof are provided. The surface composite film structure includes a nano dielectric layer arranged on a surface of a silicon substrate, a silicide layer arranged on the nano dielectric layer and a polycrystalline silicon layer arranged on the silicide layer. A material of the nano dielectric layer is a hydrogenated silicon oxide film, a material of the silicide layer is a hydrogenated carbon nitride silicon film including phosphorus or boron, and a material of the polycrystalline silicon layer is a phosphorus-doped or boron-doped polycrystalline silicon film. The surface composite film structure can achieve an excellent passivation effect and has the characteristics of longitudinal non-conduction and transverse conduction, and the transverse sheet resistance is flexibly adjustable, meeting the performance requirements of new silicon-based semiconductor physical devices.

Claims

1. A surface composite film structure with longitudinal transmission cutoff and transverse transmission conduction, comprising a nano dielectric layer arranged on a surface of a silicon substrate, a silicide layer arranged on the nano dielectric layer and a polycrystalline silicon layer arranged on the silicide layer, wherein a material of the nano dielectric layer is a hydrogenated silicon oxide film, a material of the silicide layer is a hydrogenated carbon nitride silicon film comprising phosphorus or boron, and a material of the polycrystalline silicon layer is a phosphorus-doped polycrystalline silicon film or a boron-doped polycrystalline silicon film.

2. The surface composite film structure according to claim 1, wherein a refractive index of the silicide layer is 1.5-3.0, and a transmittance of the silicide layer above 400 nm is greater than 97%.

3. The surface composite film structure according to claim 1, wherein a carbon concentration of the silicide layer is 110.sup.21 cm.sup.3-210.sup.22 cm.sup.3, and a nitrogen concentration of the silicide layer is 510.sup.21 cm.sup.3-410.sup.22 cm.sup.3.

4. The surface composite film structure according to claim 1, wherein a phosphorus/boron concentration of the silicide layer is 110.sup.19 cm.sup.3-110.sup.21 cm.sup.3.

5. The surface composite film structure according to claim 1, wherein a thickness of the nano dielectric layer is 1-20 nm, and a thickness of the silicide layer is greater than 10 nm.

6. The surface composite film structure according to claim 1, wherein a hydrogen concentration of the nano dielectric layer is 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3, and a hydrogen concentration of the silicide layer is 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3.

7. The surface composite film structure according to claim 1, wherein the material of the polycrystalline silicon layer is the phosphorus-doped polycrystalline silicon film with an activation concentration range of 110.sup.19 cm.sup.3-110.sup.21 cm.sup.3, or the material of the polycrystalline silicon layer is the boron-doped polycrystalline silicon film with an activation concentration range of 510.sup.18 cm.sup.3-510.sup.20 cm.sup.3.

8. The surface composite film structure according to claim 1, wherein the silicon substrate comprises hydrogen element, carbon element and nitrogen element, and a concentration of each element of the hydrogen element, the carbon element and the nitrogen element gradually decreases from the surface of the silicon substrate to a body of the silicon substrate; and the surface of the silicon substrate comprises a hydrogen concentration of 110.sup.19 cm.sup.3-110.sup.21 cm.sup.3, a nitrogen concentration of 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3, and a carbon concentration of 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3.

9. The surface composite film structure according to claim 1, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

10. A preparation method of the surface composite film structure according to claim 1, comprising the following steps: S1, cleaning the silicon substrate; S2, preparing a silicon oxide film on the surface of the silicon substrate; S3, depositing an amorphous silicon film comprising carbon element and nitrogen element; S4, depositing an amorphous silicon film doped with the phosphorus or the boron; S5, performing a high-temperature annealing treatment to diffuse the carbon element and the nitrogen element into the silicon substrate and transforming the amorphous silicon film doped with the phosphorus or the boron into a polycrystalline silicon film; and S6, performing a hydrogenation treatment.

11. The preparation method according to claim 10, wherein between the step S2 and the step S3, the preparation method comprises a step of depositing one or a laminated film of more selected from aluminum oxide, silicon nitride, silicon oxide and silicon nitride oxide.

12. A silicon-based semiconductor device, comprising the surface composite film structure according to claim 1.

13. The surface composite film structure according to claim 2, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

14. The surface composite film structure according to claim 3, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

15. The surface composite film structure according to claim 4, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

16. The surface composite film structure according to claim 5, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

17. The surface composite film structure according to claim 6, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

18. The surface composite film structure according to claim 7, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

19. The surface composite film structure according to claim 8, wherein a hydrogen-rich dielectric layer is provided between the silicide layer and the polycrystalline silicon layer, and a material of the hydrogen-rich dielectric layer is one or a laminated film of more selected from hydrogenated aluminum oxide film, hydrogenated silicon nitride film, hydrogenated silicon nitride oxide film and the hydrogenated silicon oxide film.

20. The preparation method according to claim 10, wherein in the surface composite film structure, a refractive index of the silicide layer is 1.5-3.0, and a transmittance of the silicide layer above 400 nm is greater than 97%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a schematic diagram showing the structure of the surface composite film structure in a specific embodiment of the present invention.

[0036] FIG. 2 is a schematic diagram showing the structure of another surface composite film structure in a specific embodiment of the present invention.

[0037] FIG. 3 is a process flow chart of the surface composite film structure in a specific embodiment of the present invention.

EXPLANATION OF REFERENCE NUMBERS IN THE DRAWINGS

[0038] 1silicon substrate, 2nano dielectric layer, 3silicide layer, 4polycrystalline silicon layer, 5hydrogen-rich dielectric layer.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] In order to make the above-mentioned features and advantages of the present invention more obvious and easier to understand, the specific embodiments of the present invention are described in detail below in conjunction with the drawings. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0040] It should be noted that the endpoints and any values of the ranges disclosed in the present article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For the numerical range, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present article.

[0041] The specific embodiment of the present invention provides a surface composite film structure, which includes the characteristics of longitudinal transmission cutoff and transverse transmission conduction. The typical structure of the surface composite film structure is shown in FIG. 1, including the nano dielectric layer 2, the silicide layer 3 and the polycrystalline silicon layer 4 stacked on the surface of the silicon substrate 1 in sequence.

[0042] The material of the nano dielectric layer 2 is a hydrogenated silicon oxide film, the main components of which are silicon, oxygen and hydrogen. The hydrogen concentration in the nano dielectric layer 2 is >110.sup.19 cm.sup.3, and the typical hydrogen concentration range is 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3. Its thickness is above 1 nm, the typical thickness range is 1-20 nm, and the preferred thickness is 1-2 nm. The transmittance of the nano dielectric layer 2 above 400 nm is greater than 97%, and the absorption coefficient k value decreases to nearly 0 at a wavelength above 400 nm, and the nano dielectric layer 2 has extremely low optical absorption characteristics.

[0043] The material of the silicide layer 3 is a hydrogenated carbon nitride silicon film including phosphorus or boron, and the main components are silicon, nitrogen, carbon, hydrogen, and phosphorus or boron; the silicide layer 3 can also include oxygen elements. Its thickness is above 10 nm. The transmittance of the silicide layer 3 above 400 nm is greater than 97%, and the absorption coefficient k value decreases to nearly 0 at a wavelength above 400 nm, and the silicide layer 3 has extremely low optical absorption characteristics. The carbon concentration of the silicide layer is 110.sup.21 cm.sup.3-210.sup.22 cm.sup.3, the nitrogen concentration of the silicide layer is 510.sup.21 cm.sup.3-410.sup.22 cm.sup.3, the ratio of carbon, nitrogen and other elements in the silicide layer 3 can be adjusted, and the range of its refractive index is 1.5-3.0, which can be adjusted according to the composition. The boron/phosphorus concentration in the silicide layer 3 is adjustable, and the typical concentration range is 110.sup.19 cm.sup.3-110.sup.21 cm.sup.3. The hydrogen concentration in the silicide layer 3 is >110.sup.19 cm.sup.3, and the typical concentration range is 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3.

[0044] The material of the polycrystalline silicon layer 4 is a phosphorus-doped or boron-doped polycrystalline silicon film. The activation concentration range of the phosphorus-doped polycrystalline silicon film is usually 110.sup.19-110.sup.21 cm.sup.3, and the activation concentration range of the boron-doped polycrystalline silicon film is 510.sup.18 cm.sup.3-510.sup.20 cm.sup.3. The thickness of the polycrystalline silicon layer 4 is adjustable. By adjusting its thickness, the transmittance of the surface composite film structure can be changed.

[0045] The silicon substrate 1 includes hydrogen, nitrogen, carbon, and phosphorus or boron elements near the surface and in the body, and the concentration of the corresponding elements gradually decreases from the surface to the body. Among them, in the surface area below the nano dielectric layer 2, the nitrogen concentration is generally higher than 110.sup.19 cm.sup.3, and the typical concentration range is 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3; the carbon concentration is generally higher than 110.sup.19 cm.sup.3, and the typical concentration range is 110.sup.19 cm.sup.3-110.sup.22 cm.sup.3; the hydrogen concentration is generally higher than 110.sup.19 cm.sup.3, and the typical concentration range is 110.sup.19 cm.sup.3-110.sup.21 cm.sup.3.

[0046] Combined with FIG. 2, another typical structure of the surface composite film structure is shown in FIG. 2, including the nano dielectric layer 2, the silicide layer 3, the hydrogen-rich dielectric layer 5 and the polycrystalline silicon layer 4 stacked on the surface of the silicon substrate 1 in sequence. The characteristics of the silicon substrate 1, the nano dielectric layer 2, the silicide layer 3, and the polycrystalline silicon layer 4 are the same as the surface composite film structure of the above-mentioned embodiment.

[0047] Among them, the material of the hydrogen-rich dielectric layer 4 is hydrogenated aluminum oxide, hydrogenated silicon nitride, hydrogenated silicon oxide, hydrogenated silicon nitride oxide or a combination of these laminated films. The range of the hydrogen concentration of the hydrogen-rich dielectric layer 4 is 110.sup.20 cm.sup.3-110.sup.22 cm.sup.3. The hydrogen-rich dielectric layer may also include boron or phosphorus elements.

[0048] Combined with FIG. 3, the typical preparation method of the above-mentioned surface composite film structure includes the following steps: [0049] S1, performing standard radio corporation of America (RCA) cleaning on the silicon substrate. [0050] S2, preparing a silicon oxide film on the surface of the silicon substrate, where the preparation method includes wet chemical method, plasma assisted oxidation method, thermal oxidation method, ozone oxidation method, etc. [0051] S3, depositing an amorphous silicon film including carbon and nitrogen elements on the silicon oxide film. The typical preparation method is plasma-enhanced chemical vapor deposition (PECVD) in-situ deposition method, and the range of the deposition temperature is 100 C. -600 C. . [0052] S4, depositing an amorphous silicon film doped with phosphorus or boron on the amorphous silicon film; or first depositing a hydrogen-rich dielectric layer on the amorphous silicon film, and then depositing an amorphous silicon film doped with phosphorus or boron on the hydrogen-rich dielectric layer. [0053] S5, performing high-temperature annealing to diffuse carbon and nitrogen elements into the silicon substrate and transforming the amorphous silicon film doped with phosphorus or boron into a polycrystalline silicon film. The typical temperature range is 600 C. -1200 C. , preferably 900-950 C. . [0054] S6, performing hydrogenation treatment. The hydrogenation treatment method includes: annealing or light annealing in hydrogen-containing atmosphere to achieve hydrogen injection; or depositing a hydrogen-rich dielectric film, followed by low-temperature annealing, and then cleaning and etching to remove the hydrogen-rich dielectric film.

[0055] The above-mentioned surface composite film structure has excellent surface passivation effect and has the characteristics of longitudinal non-conduction and transverse conduction, which is suitable for new silicon-based semiconductor device. Its preparation method is fully compatible with prior production line technology, has low preparation cost, high stability, and good industrial application prospects.

[0056] The technical solution and effect of the present invention are described below through specific examples.

Example 1

[0057] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a PECVD chamber, N.sub.2O plasma is used to prepare SiO.sub.x film, then a 10 nm nitrogen-rich and carbon-rich amorphous silicon film (carbon concentration is 110.sup.22 cm.sup.3, nitrogen concentration is 110.sup.22 cm.sup.3) is deposited, and then a 30 nm phosphorus-doped amorphous silicon film is deposited; high temperature annealing is performed at 900 C. in a tube furnace for 30 min; and finally, annealing is performed at 400 C for 60 min in nitrogen/hydrogen mixed gas atmosphere. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 0.5-1 fA/cm.sup.2, the transverse sheet resistance range is 1000-1600 /sq, the longitudinal contact resistivity cannot be measured, and the transmittance at a wavelength of 400 nm is about 90%.

Example 2

[0058] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a PECVD chamber, N.sub.2O plasma is used to prepare SiO.sub.x film, and then a 10 nm nitrogen-rich and carbon-rich amorphous silicon film (carbon concentration is 210.sup.22 cm.sup.3, nitrogen concentration is 510.sup.21 cm.sup.3) is deposited, and then a 200 nm phosphorus-doped amorphous silicon film is deposited; high temperature annealing is performed at 900 C. in a tube furnace for 30 min; and finally, annealing is performed at 400 C. for 60 min in nitrogen/hydrogen mixed gas atmosphere. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 1.0-2.0 fA/cm.sup.2, the transverse sheet resistance range is 20-40 /sq, the longitudinal contact resistivity cannot be measured, and the transmittance at a wavelength of 400 nm is about 50%.

Example 3

[0059] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a PECVD chamber, N.sub.2O plasma is used to prepare SiO.sub.x film, and then a 10 nm nitrogen-rich and carbon-rich amorphous silicon film (carbon concentration is 110.sup.22 cm.sup.3, nitrogen concentration is 110.sup.22 cm.sup.3) is deposited; then atomic layer deposition (ALD) is used to deposit AlO.sub.x, and then transferred to PECVD to deposit SiN.sub.x; then a 30 nm phosphorus-doped amorphous silicon film is deposited; high temperature annealing is performed at 900 C. in a tube furnace for 30 min; then ALD is used to deposit AlO.sub.x, and then transferred to PECVD to deposit SiN.sub.x for hydrogenation treatment; and then AlO.sub.x/SiN.sub.x is etched using hydrofluoric acid (HF) solution. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 0.2-0.5 fA/cm.sup.2, the transverse sheet resistance range is 1000-1600 /sq, the longitudinal contact resistivity cannot be measured, and the transmittance at a wavelength of 400 nm is about 90%.

Example 4

[0060] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a PECVD chamber, N.sub.2O plasma is used to prepare SiO.sub.x film, then a 10 nm nitrogen-rich and carbon-rich amorphous silicon film (carbon concentration is 110.sup.21 cm.sup.3, nitrogen concentration is 310.sup.22 cm.sup.3) is deposited, SiN.sub.x is deposited, and then 200 nm phosphorus-doped amorphous silicon film is deposited; high temperature annealing is performed at 900 C. in a tube furnace for 30 min; then ALD is used to deposit AlO.sub.x, and then transferred to PECVD to deposit SiN.sub.x for hydrogenation treatment; and AlO.sub.x/SiN.sub.x is subsequently etched using HF solution. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 0.5-1.2 fA/cm.sup.2, the transverse sheet resistance range is 20-40 /sq, the longitudinal contact resistivity cannot be measured, and the transmittance at a wavelength of 400 nm is about 50%.

Comparative Example 1

[0061] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in ALD chamber; AlO.sub.x is deposited and then transferred to a tube furnace, and annealing is performed at 450 C. for 30 min in nitrogen atmosphere. Six samples are prepared to perform Sinton tests, the single-sided saturation current density J.sub.0,s test results range is 3.0-5.0 fA/cm.sup.2, and both longitudinal contact resistivity and transverse sheet resistance cannot be measured.

Comparative Example 2

[0062] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with resistivity 1-7 .Math.cm. After standard RCA cleaning, the silicon wafer is placed in ALD chamber; AlO.sub.x is deposited and then transferred to a tube furnace, annealing is performed at 450 C. for 30 min in nitrogen atmosphere, and transferred to PECVD to deposit SiN.sub.x, finally transferred to the tube furnace, and annealing is performed at 400 C. for 60 min in nitrogen/hydrogen mixed gas. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 2.0-4.0 fA/cm.sup.2, and both the longitudinal contact resistivity and transverse sheet resistance cannot be measured.

Comparative Example 3

[0063] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a tube furnace to prepare SiO.sub.x in oxygen atmosphere, and then transferred to a PECVD chamber to deposit SiN.sub.x; and finally, annealing is performed at 400 C. for 60 min in a tube furnace under a nitrogen/hydrogen mixed gas. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 8.0-12.0 fA/cm.sup.2, and both longitudinal contact resistivity and transverse sheet resistance cannot be measured.

Comparative Example 4

[0064] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a tube furnace to prepare SiO.sub.x in oxygen atmosphere, and then transferred to a PECVD chamber to deposit SiN.sub.x; annealing is performed at 400 C. for 60 min under a nitrogen/hydrogen mixed gas; and then a layer of about 60 nm ITO film is deposited on the surface by magnetron sputtering. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 20-40 fA/cm.sup.2, the transverse sheet resistance range is 40-60 /sq, and the longitudinal contact resistivity cannot be measured.

Comparative Example 5

[0065] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a tube furnace to prepare SiO.sub.x in oxygen atmosphere, and then transferred to a PECVD chamber to deposit 120 nm of phosphorus-doped amorphous silicon; then annealing is performed at 900 C. for 30 min in nitrogen/hydrogen mixed gas atmosphere in a tube furnace; and finally annealing is performed at 400 C. for 60 min in nitrogen/hydrogen mixed gas atmosphere. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 1.0-3.0 fA/cm.sup.2, the transverse sheet resistance range is 30-50 /sq, and the longitudinal contact resistivity range is 0.001-0.003 cm.sup.2.

Comparative Example 6

[0066] N-type silicon wafer is prepared, which is flat, with 110 m thick, and with 1-7 .Math.cm resistivity. After standard RCA cleaning, the silicon wafer is placed in a tube furnace to prepare SiO.sub.x in ozone atmosphere, and then transferred to a PECVD chamber to deposit 120 nm of phosphorus-doped amorphous silicon; then annealing is performed at 880 C. for 30 min under nitrogen/hydrogen mixed gas atmosphere in a tube furnace; and finally annealing is performed at 400 C. for 60 min under nitrogen/hydrogen mixed gas atmosphere. Six samples are prepared to perform Sinton tests. The single-sided saturation current density J.sub.0,s test results range is 6.0-10.0 fA/cm.sup.2, the transverse sheet resistance range is 50-70 /sq, and the longitudinal contact resistivity range is 0.002-0.004 cm.sup.2.

[0067] The single-sided saturation current density (J.sub.0,s), transverse sheet resistance and longitudinal contact resistivity of the passivated sheets prepared in Examples 1-4 and Comparative Examples 1-6 are compared, and the results are shown in Table 1 below. The results show that the surface composite film structure of the present invention has an excellent passivation effect, which can greatly reduce the saturation current density on the surface of the silicon wafer and has the characteristics of longitudinal non-conduction and transverse conduction.

TABLE-US-00001 TABLE 1 Comparison of passivated sheet performance between Examples 1-4 and Comparative Examples 1-6 Parameters J.sub.0, s (fA/cm.sup.2) R.sub.sq (/sq) .sub.c ( .Math. cm.sup.2) Example 1 0.5-1.0 1000-1600 Example 2 1.0-2.0 20-40 Example 3 0.2-0.5 1000-1600 Example 4 0.5-1.2 20-40 Comparative 3.0-5.0 Example 1 Comparative 2.0-4.0 Example 2 Comparative 8.0-12.0 Example 3 Comparative 20.0-40.0 40-60 Example 4 Comparative 1.0-3.0 30-50 0.001-0.003 Example 5 Comparative 6.0-10.0 50-70 0.002-0.004 Example 6

[0068] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.