METHOD FOR PREPARING COPPER THIN FILM BY USING SINGLE CRYSTAL COPPER TARGET

Abstract

A method of manufacturing a copper thin film using a single-crystal copper target, and more particularly, a method of manufacturing a copper thin film using a single-crystal copper target, wherein a copper thin film is deposited on a sapphire disk substrate through high-frequency sputtering using a single-crystal copper target grown through a Czochralski process, and may thus exhibit high quality in terms of crystallinity. The method includes depositing a copper thin film on a sapphire disk substrate through a high-frequency sputtering process using a disk-shaped single-crystal copper target obtained by cutting cylindrical single-crystal copper grown through a Czochralski process.

Claims

1. A method of manufacturing a copper thin film using a single-crystal copper target, comprising depositing a copper thin film on a sapphire disk substrate through a high-frequency sputtering process using a disk-shaped single-crystal copper target obtained by cutting a cylindrical single-crystal copper grown through a Czochralski process.

2. The method of claim 1, wherein a height of a peak (111) of the copper thin film is at least one times a height of a peak (0001) of the sapphire disk substrate on an X-ray diffraction (XRD) pattern.

3. The method of claim 1, wherein, in the copper thin film, a resistivity drop, in which a resistivity is lower than an average resistivity, occurs in a range from room temperature to 200° C.

4. The method of claim 1, wherein the high-frequency sputtering is performed by applying a high-frequency power of 30 to 60 W at 100 to 200° C. for 2 to 3 hr.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 shows XRD data for the comparison of a copper thin film manufactured according to a preferred embodiment of the present invention and a copper thin film manufactured by a conventional process;

[0014] FIG. 2 shows AFM data for the comparison of the copper thin film manufactured according to a preferred embodiment of the present invention and the copper thin film manufactured by a conventional process;

[0015] FIG. 3 shows TEM images for the comparison of the copper thin film manufactured according to a preferred embodiment of the present invention and the copper thin film manufactured by a conventional process;

[0016] FIG. 4 shows EBSD images for the comparison of the copper thin film manufactured according to a preferred embodiment of the present invention and the copper thin film manufactured by a conventional process; and

[0017] FIG. 5 shows Hall data for the comparison of the copper thin film manufactured according to a preferred embodiment of the present invention and the copper thin film manufactured by a conventional process.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention addresses a method of manufacturing a copper thin film using a single-crystal copper target, suitable for forming a copper thin film for use in a solar cell or the like on the surface of a substrate.

[0019] In particular, the method of manufacturing a copper thin film using a single-crystal copper target according to the present invention enables the formation of a high-quality copper thin film through a relatively simple process compared to conventional methods, in order to meet the high demand for the copper thin film.

[0020] Here, the copper target is a disk-shaped single-crystal copper target obtained by cutting cylindrical single-crystal copper grown through a Czochralski process, the substrate is a sapphire disk-shaped substrate, and the deposition process is a high-frequency sputtering process.

[0021] A disk-shaped single-crystal copper ingot, grown through a Czochralski process for preparing a single-crystal ingot, is deposited on the surface of a sapphire disk substrate by way of a high-frequency sputtering process, thus yielding a high-quality copper thin film.

[0022] The height of a peak (111) of the copper thin film is at least one times the height of a peak (0001) of the sapphire disk substrate on an XRD pattern. Also, the copper thin film is characterized in that a resistivity drop, in which resistivity drastically decreases compared to an average resistivity, occurs in the range of room temperature to 200° C.

[0023] Here, the high-frequency sputtering deposition process is performed by applying a high-frequency power of 30 to 60 W at 100 to 200° C. for 1 to 3 hr in a vacuum. When the processing conditions fall out of the above conditions, the properties of the copper thin film are not exhibited as desired and the quality of the copper thin film may decrease. Hence, the process is preferably carried out under the processing conditions, which are appropriately selected within the above ranges.

[0024] Below is a description of a method of manufacturing a copper thin film using a single-crystal copper target according to a preferred embodiment of the present invention and the properties of a copper thin film manufactured thereby.

[0025] Specifically, the method of manufacturing a copper thin film using a single-crystal copper target according to a preferred embodiment of the present invention is described as follows.

[0026] 1. A cylindrical single-crystal copper ingot is grown through a Czochralski process.

[0027] 2. The cylindrical single-crystal copper ingot is vertically erected and cut in a horizontal direction to obtain a disk shape, thus forming a disk-shaped single-crystal copper target.

[0028] 3. The disk-shaped single-crystal copper target is subjected to high-frequency sputtering by applying a high-frequency power of 40 W at 150° C. for 2 hr so as to deposit a copper thin film on the surface of a disk-shaped sapphire substrate, thereby completing the formation of a copper thin film.

[0029] Next, the properties of the copper thin film manufactured according to a preferred embodiment of the present invention are described in detail based on various test data results.

[0030] 1. XRD data.

[0031] FIG. 1 shows XRD data for the comparison of a copper thin film (SCu/Al.sub.2O.sub.3) manufactured according to a preferred embodiment of the present invention and a copper thin film (Cu/Al.sub.2O.sub.3) manufactured by a conventional process using a typical copper target.

[0032] As shown in the left data of FIG. 1, the copper thin film (SCu/Al.sub.2O.sub.3) of the present invention can be confirmed to exhibit superior crystallinity of a Cu (111) plane, compared to the conventional copper thin film (Cu/Al.sub.2O.sub.3) using the typical copper target.

[0033] As shown in the right data of FIG. 1, the peak of Cu (111) of the copper thin film (SCu/Al.sub.2O.sub.3) according to the present invention appears to be much higher than the peak of the sapphire substrate (Al.sub.2O.sub.3 (0001)). On the other hand, in the case of the conventional copper thin film (Cu/Al.sub.2O.sub.3), the peak of the thin film is not higher than the peak of the substrate. Specifically, the peak intensity of the copper thin film (SCu/Al.sub.2O.sub.3) is ensured to a level equal to or higher than 106 CPS (counts per second), thereby making it possible to grow a high-quality copper thin film.

[0034] 2. AFM data

[0035] FIG. 2 shows AFM data for the comparison of the copper thin film (SCu/Al.sub.2O.sub.3) manufactured according to a preferred embodiment of the present invention and the copper thin film (Cu/Al.sub.2O.sub.3) manufactured by a conventional process using a typical copper target.

[0036] As shown in the AFM data of FIG. 2, the morphology of the copper thin film (SCu/Al.sub.2O.sub.3) of the present invention is uniform but the morphology of the conventional copper thin film is non-uniform. The copper thin film (SCu/Al.sub.2O.sub.3) of the present invention has an RMS (9.11 nm) that is lower than the RMS (45.09 nm) of the conventional copper thin film (Cu/Al.sub.2O.sub.3).

[0037] 3. TEM image

[0038] FIG. 3 shows TEM images for the comparison of the copper thin film (SCu/Al.sub.2O.sub.3) manufactured according to a preferred embodiment of the present invention and the copper thin film (Cu/Al.sub.2O.sub.3) manufactured through a conventional process using a typical copper target.

[0039] As shown in the TEM images of FIG. 3, the copper thin film (SCu/Al.sub.2O.sub.3) of the present invention is configured such that lattices are uniformly formed like single crystals at the boundary between the substrate and the copper thin film. Also, as seen in the SAED (Selected Area Electron Diffraction) insertion, the copper thin film can be found to be effectively formed on the surface of the substrate.

[0040] However, the conventional copper thin film (Cu/Al.sub.2O.sub.3) is configured such that a large number of layer defects and crystal dislocations are formed at the boundary between the thin film and the substrate. As seen in the inserted TEM image, a columnar structure can be confirmed to grow.

[0041] 4. EBSD image

[0042] FIG. 4 shows EBSD images for the comparison of the copper thin film (SCu/Al.sub.2O.sub.3) manufactured according to a preferred embodiment of the present invention and the copper thin film (Cu/Al.sub.2O.sub.3) manufactured by a conventional process using a typical copper target.

[0043] As shown in the EBSD images of FIG. 4, the copper thin film of the present invention is configured such that no grains are found throughout the entire region of the EBSD image, and is grown in the same (111) direction.

[0044] 5. Hall data

[0045] FIG. 5 shows Hall data for the comparison of the copper thin film (SCu/Al.sub.2O.sub.3) manufactured according to a preferred embodiment of the present invention and the copper thin film (Cu/Al.sub.2O.sub.3) manufactured by a conventional process using a typical copper target (using van der Pauw's law).

[0046] Based on the Hall data of FIG. 5, in the copper thin film (SCu/Al.sub.2O.sub.3) of the present invention, a resistivity drop, in which resistivity drastically decreases, occurs at about 150° C., as is apparent from (a), but the conventional copper thin film (Cu/Al.sub.2O.sub.3) shows that changes in resistivity fall in the predetermined range, as seen in (b). Also, in the copper thin film (SCu/Al.sub.2O.sub.3) of the present invention, carrier concentration and mobility are remarkably increased at about 150° C., as seen in (c), but the conventional copper thin film (Cu/Al.sub.2O.sub.3) is gradually decreased or increased in carrier concentration and mobility with an increase in temperature, as seen in (d).

[0047] The copper thin film (SCu/Al.sub.2O.sub.3) of the present invention has low resistivity properties by virtue of the surface effects thereof and the grain boundary contribution, and is thus highly applicable to ULSI (Ultra-Large Scale Integration) technology.

[0048] As described hereinbefore, the method of manufacturing a copper thin film using a single-crystal copper target according to the present invention enables the deposition of a copper thin film on the surface of a sapphire substrate through high-frequency sputtering using a single-crystal copper target, and thus the resulting copper thin film may exhibit high quality while achieving superior crystallinity, uniform morphology, uniform grain distribution and resistivity properties, compared to the conventional copper thin film.

[0049] The above embodiment is merely exemplary, and other embodiments variously modified therefrom may be provided by those skilled in the art.

[0050] Therefore, the technical scope of the present invention should include not only the above embodiment but variously modified embodiments that fall within the technical spirit of the invention disclosed in the accompanying claims.

[0051] The present invention pertains to a method of manufacturing a copper thin film using a single-crystal copper target, and more particularly to a method of manufacturing a copper thin film using a single-crystal copper target, in which a copper thin film is deposited on a sapphire disk substrate through high-frequency sputtering using a single-crystal copper target grown through a Czochralski process, and can thus be applied to the field of the formation of a copper thin film having high quality in terms of crystallinity.